JPH08323639A - Impact type screw tightening device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] The tightening force of the screw can be detected, and even if the tightening ability of the tool is reduced, it can be adequately handled and the outflow of defective tightening products can be prevented. Provided is an impact type screw tightening device that can be used. [Structure] An impact / torque generator 3, a main shaft 4 having a screw joint portion 6 at one end and being driven by a drive unit 3 to tighten the screw, and a torque detecting unit for detecting a torque change of the main shaft 4. Based on the detection result of the torque detecting means 5, the control device 7 including the calculating means for detecting the tightening ability decrease of the main body 1 based on the detection result of the impact type screw tightener main body 1 having the torque detector 5 and the torque detecting means 5. Control device 7 including a control means for controlling a power source applied to the driving means 3 in order to realize a target fastening force, and when the tightening ability detected by the computing means falls below a specified value, a tightening ability decrease abnormality is detected. An impact type screw tightening device including a control device 7 including an abnormality determining means for determining.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening device for performing screw tightening work using impact force, for example, impact
The present invention relates to a wrench, an impact-type nut / runner, and the like, and more particularly to a technology for controlling the fastening force (tightening force) of a screw.

[0002]

2. Description of the Related Art As a conventional impact wrench for controlling a fastening force, there is, for example, a device described in Japanese Patent Application No. 5-333988 and a drawing (unpublished).

FIG. 13 is a sectional view of the above device.

In FIG. 13, the main shaft 102 of the impact wrench body 101 is made of a material having a magnetostrictive effect. And the impact that occurs when tightening screws
A change in torque is detected by detecting a change in magnetic permeability on the surface of the main shaft 102 due to torque as a change in inductance of the detection coils 103a and 103b of the torque detection unit 103. Further, a control device 104 is connected to the impact wrench body 101, the fastening force is calculated according to the procedure of the flowchart shown in FIG. 14 based on the signal from the torque detection unit 103, and the target fastening force is reached. by the way,
The shut-off valve 105 is closed by a control signal from the control device 104 to shut off the compressed air to the air motor unit 106, whereby the hydraulic pulse generator 107 is closed.
And driving of the main shaft 102 is stopped.

The procedure for calculating and controlling the fastening force will be described below with reference to the flowchart shown in FIG.

First, in step S201, the target fastening force _C F
After setting the value of _C and the seating determination threshold free running time _S t _FR in step S202,
In step S203, the impact number counter is reset <count i = 0>, and in step S204, the value of the fastening force up to that time is reset <F (0) = 0).

Next, in step S205, screw tightening is started.

Further, steps S206 to S20
8 forms a loop, and seating determination is performed for each impact until seating.

In this loop, first, step S2
After incrementing the count i by 1 at 06, step S2
The free running time t from the signal of the torque sensor at 07
_{Calculate FR} .

[0010] Next, in step S208, the free-running time _{t FR} is determined whether the sitting determination threshold free running time _S t _FR hereinafter to S208 returns to step S206 if NO, that is not yet seated Repeat.

On the other hand, if YES in step S208, that is, if it is determined that the player is seated, steps S209-
Proceeding to a loop including steps S212 and S213, the fastening force is calculated for each impact.

In this loop, first, step S2
At 09, the impact peak torque value T _P (i) is obtained from the signal of the torque sensor and stored. At the time of sitting, the peak torque value T is calculated from the torque signal temporarily stored in step S207.
_It suffices to find _P (i).

Next, in step S210, F (i-
The torque-fastening force conversion coefficient C _TF (i) in 1) is
Calculation is performed based on the table of the fastening force data / memory unit. However, _CTF (i) = _CTF [F (i-1)].

Next, in step S211, the amount of increase in fastening force due to impact is δF (i) = C _TF (i) × T.
_P (i) is calculated, and the fastening force F (i) after the impact is further added to the fastening force up to that time, that is, the fastening force F (i-1) after the impact one time before, by the increment δF ( i)
Calculate by adding. Therefore, F (i) = F (i−1) + C _TF (i) × T _P (i) Next, in step S212, the fastening force F after impact is calculated.
(I) it is determined whether the target engagement force _C F _C or more, after the count i is increased by 1 in step S213, if NO, the repeated up to step S212 returns to step S209.

On the other hand, if YES in step S212, the flow advances to step S214, at which point a cut-off command is issued. This causes the compressed air valve to close.

Next, in step S215, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process returns to step S203 to perform the next screw tightening.

In the above description of the prior art, the impact wrench is taken as an example, but the same applies to the impact type nut runner and the like.

[0018]

As described above, there is a risk that the tightening ability will decrease due to the repeated use of the tool, etc., and it is an object to be able to cope with the case where the tightening ability decreases. Was there.

[0019]

An object of the present invention is to solve the problems of the prior art as described above, to detect the tightening force (tightening force) of a screw when tightening the screw, and to constantly monitor the deterioration of the tightening ability of the tool. The impact type screw tightening device that can prevent the outflow of defective tightening products during screw tightening work can be dealt with even when the tightening ability is reduced due to repeated use of tools. Has an aim.

[0020]

In order to achieve the above object, the present invention is constructed as described in the claims.

That is, in the impact type screw tightening device according to the first aspect of the invention, there is provided a driving means having a pulse component in the driving output and a screw joint at one end, and the driving means is driven by the driving means. A main shaft for tightening a screw, an impact type screw tightener main body having a torque detecting means for detecting a torque change of the main shaft, and a decrease in tightening ability of the impact type screw tightener main body is detected based on a detection result of the torque detecting means. The present invention is characterized in that the calculation means and the control means for controlling the power source applied to the drive means to realize the target fastening force based on the detection result of the torque detection means are provided.

In this case, the main body of the impact type screw tightener corresponds to, for example, the main body 1 of the impact type screw tightener in the embodiment shown in FIG. 1 described later, and similarly, the driving means is the motor 2 and the torque pulse generator. 3 corresponds to the portion 3 and the spindle and the torque detecting means are respectively the spindle 4
And may correspond to the torque detector 5. Further, the arithmetic means and the control means may correspond to, for example, the control device 7 in the embodiment of FIG. 1 described later.

Further, in the invention described in claim 2,
The impact type screw tightening device according to claim 1,
The present invention is characterized in that an abnormality determining means for determining that the tightening ability is abnormal when the tightening ability detected by the calculating means is reduced to a prescribed value or less is provided.

In this case, the abnormality determining means is, for example,
It may correspond to the control device 7 in the embodiment of FIG. 1 described later.

Further, in the invention according to claim 3, in the impact type screw tightening device according to claim 2, the calculating means also has a function of judging seating from the detection result of the torque detecting means, and The first torque pulse and the second torque pulse generated from among the plurality of torque pulses included in each impact before seating based on the detection result of the torque detecting means for detecting the deterioration of the tightening ability. With the occurrence interval, that is, the function of detecting the free running time,
In addition, the abnormality determining means has a function of determining that the tightening ability is abnormal when the free running time does not reach a predetermined value.

In this case, the calculating means and the abnormality determining means may correspond to, for example, the control device 7 in the embodiment shown in FIG.

Furthermore, in the invention according to claim 4, in the impact type screw tightening device according to claim 2, the calculating means also has a function of judging seating from the detection result of the torque detecting means, and , A function of detecting the peak value of the first torque pulse generated from among the plurality of torque pulses included in each impact before seating, from the detection result of the torque detecting means in order to detect the tightening ability deterioration. The abnormality determining means has a function of determining that the tightening ability is abnormal when the peak value of the first torque pulse generated first does not reach a predetermined value. It is characterized by that.

In this case, the calculating means and the abnormality determining means are, for example, the control device 37 in the embodiment shown in FIG.
Can be equivalent to.

Further, in the invention according to claim 5, in the impact type screw tightening device according to claim 2, the calculating means is seated from the detection result of the torque detecting means in order to detect a decrease in tightening ability. Of the plurality of torque pulses included in the time impact, and has a function of detecting the peak value of the second torque pulse generated, and the abnormality determining means is the second generated. It is characterized in that it has a function of determining that the tightening ability is abnormal when the peak value of the torque pulse does not reach a predetermined value.

In this case, the calculating means and the abnormality determining means are, for example, the control device 47 in the embodiment shown in FIG.
Can be equivalent to.

Furthermore, in the invention according to claim 6, in the impact type screw tightening device according to claim 2, the calculating means is seated from the detection result of the torque detecting means in order to detect a decrease in tightening ability. It has a function of detecting the duration of the torque pulse at the time of impact, and the abnormality determining means determines that the tightening ability is abnormal when the duration of the torque pulse does not reach a predetermined value. It is characterized by having a function to do.

In this case, the calculating means and the abnormality determining means are, for example, the control device 57 in the embodiment shown in FIG.
Can be equivalent to.

Further, in the invention described in claim 7, in the impact type screw tightening device according to any one of claims 1 to 6, the calculating means is obtained from the detection result of the torque detecting means. The control means also has a function of calculating the increasing amount of the fastening force for each impact using the peak torque value and sequentially obtaining the fastening force, and the control means obtains the fastening force obtained for each impact by a predetermined value. It is characterized in that it has a function of shutting off the power source applied to the driving means at the time when the above is reached.

In this case, the arithmetic means and the control means may correspond to, for example, the control device 7 in the embodiment shown in FIG.

Further, in the invention described in claim 8, in the impact type screw tightening device according to any one of claims 1 to 6, the control means is configured to detect each impact from the detection result of the torque detection means. It is characterized in that it has a function of shutting off the power source applied to the drive means when the peak torque value obtained in (1) exceeds a predetermined value.

In this case, the control means may correspond to, for example, the control device 47 in the embodiment shown in FIG.

Furthermore, in the invention according to claim 9, in the impact type screw tightening device according to any one of claims 2 to 8, the control means determines that the abnormality determining means determines that the tightening ability is abnormal. It is characterized in that it also has a function of shutting off the power source applied to the drive means when the determination is made.

In this case, the control means may correspond to, for example, the control device 7 in the embodiment shown in FIG.

Further, in the invention described in claim 10, in the impact type screw tightening device according to any one of claims 2 to 9, it is judged when the abnormality judging means judges that the tightening ability is abnormal. It is characterized in that it is provided with a determination result output means for outputting a result.

In this case, the judgment result output means may be, for example, equivalent to the control device 7 in the embodiment shown in FIG.

Further, in the invention described in claim 11, in the impact type screw tightening device according to any one of claims 2 to 10, it is judged when the abnormality judging means judges that the tightening ability is abnormal. It is characterized in that a determination result display means for displaying a result is provided.

In this case, the determination result display means may correspond to, for example, the control device 7 in the embodiment shown in FIG.

[0043]

According to the first aspect of the present invention, the calculation means detects the tightening capability reduction of the impact type screw tightening machine main body based on the detection result of the torque detection means. In the invention described above, when the tightening ability detected by the computing means is reduced to a specified value or less, the abnormality determining means determines that the tightening ability is abnormal. Therefore, the decrease in the tightening ability of the tool is constantly monitored. Therefore, it is possible to deal with the case where the tightening ability is deteriorated due to repeated use of the tool.

Further, in the invention described in claim 3,
The impact type screw tightening device according to claim 2,
The seating is determined from the detection result of the torque detecting means, and a plurality of torques included in each impact before seating are detected.
Torque pulse generated first in the pulse and second
The operation interval of the second torque / pulse that is generated, that is, the free running time is detected by the calculating means, and when the free running time does not reach the predetermined value, the abnormality determining means determines that the tightening ability is abnormal. Therefore, in the invention according to claim 4, in the impact type screw tightening device according to claim 2, the seating is determined from the detection result of the torque detecting means, and a plurality of torques included in each impact before seating are determined. The peak value of the torque pulse generated first in the pulse is detected by the calculating means, and the abnormality determining means is used when the peak value of the torque pulse generated first does not reach the predetermined value. It is determined that the tightening ability is abnormal, and in the invention according to claim 5, the impact type screw according to claim 2 is further provided. In the device, the peak value of the second torque pulse generated among the plurality of torque pulses included in the seating impact is detected from the detection result of the torque detection means, and the second peak is generated. When the peak value of the torque pulse does not reach the predetermined value, the abnormality determining means determines that the tightening ability is abnormal, and in the invention according to claim 6,
In the impact type screw tightening device described in (1), when the duration of the torque pulse at the impact at the time of sitting is detected from the detection result of the torque detection means, and the duration of the torque pulse does not reach the predetermined value, Since the abnormality determining means determines that the tightening ability is abnormal, the decrease in the tightening ability of the tool is detected based on the detection result of the torque detecting means incorporated in the tool.

Further, in the invention described in claim 7,
Using the peak torque value obtained from the detection result of the torque detection means, the increase amount of the fastening force is calculated for each impact to sequentially obtain the fastening force, and the fastening force obtained for each impact becomes a predetermined value or more. At the time point, the power source applied to the drive means is shut off. In the invention according to claim 8, the peak torque value obtained for each impact from the detection result of the torque detection means becomes a predetermined value or more. Since the power source applied to the drive means is shut off at that time, the impact type screw tightening device controls the power source applied to the drive means based on the fastening force obtained for each impact. However, even if the power source applied to the drive means is controlled based on the peak torque value obtained for each impact, Based on the detection result of the click detecting means,
A decrease in the tool tightening ability will be detected.

Now, the change in the waveform of the impact torque before and after the sitting due to the repeated use will be described.

FIG. 11 shows a detent nut (for detent nut, for example, "Points for designing screw tightening mechanism", those described in Japan Standards Association, 1989, 4th edition, pages 299 to 301). Figure that schematically describes the impact occurrence status from the start of impact when normal tightening occurs to the seating to the completion of tightening, and the waveform of impact torque at each stage using Is. In addition, Fig. 12 shows the torque generated first in the impact before seating.
It is explanatory drawing about the peak value and free running time of a pulse, the peak value of the torque pulse generated second in the impact at the time of sitting, the duration of a torque pulse, and the change with repeated use of the final reaching fastening force. .

Here, the first torque pulse generated in the impact before seating is when the maximum static friction torque is reached after the torque starts to be applied to the stationary bolt or nut and the bolt or nut starts to rotate. The maximum static friction torque is detected as the peak value of the first torque pulse.

The free running time is from the first torque pulse described above to the second torque pulse generated when the rotating bolt or nut is gradually decelerated and stopped due to dynamic friction. Interval,
It corresponds to the rotation angle of the nut for each impact. The impact before seating occurs because the crimped portion of the detent nut hits the screw surface of the bolt, and is unique to the detent nut.

In addition, the second impact in seating
The second torque pulse generated is the torque waveform when the rotating bolt or nut gradually decelerates and stops due to dynamic friction, and the peak value of the second torque pulse generated is reached by impact. It is the sum of the dynamic friction torque corresponding to the fastening force and the rotational torque acting on the bolt or nut from the tool at that time.

Furthermore, the duration of the torque pulse at the time of seating impact is the time from when the bolt or nut begins to be torqued to when the bolt or nut rotates and then stops. The positive torque (in the tightening direction) is continuously detected because the force is generated.

As is clear from FIG. 12, the free running time in the impact before sitting, the peak value of the torque pulse secondly generated during sitting and the duration of the torque pulse increase in the number of times of repeated use. That is, in other words, in FIG. 12, when the number of shots exceeds 80,000 to 100,000, the number of shots sharply decreases and the final reached fastening force also shows the same change. Also, the first in the impact before sitting
The peak value of the torque pulse that occurs the second time gradually decreases when the final arriving fastening force begins to decrease.

The reason for this is considered as follows. That is, if the tightening capacity of the impact wrench (such as impact type screw tightening machine) is constant, the impact before the seating occurs due to the caulking part of the detent nut being in contact with the screw surface of the bolt. The peak value and the free running time of the first torque pulse generated in (3) are values within a certain range although they vary.

However, when the tightening ability of the tool is deteriorated due to the oil leak of the torque / pulse generator, the initial energy temporarily stored as an elastic twist immediately before the bolt or the nut starts to rotate decreases. Therefore, the value of the maximum static friction torque decreases, and the rotation angle of the bolt or nut for each impact decreases, so that the free running time also decreases.

When the tightening ability further deteriorates, it becomes impossible to give enough energy to rotate the bolt or nut even if an impact occurs.
The torque waveform of impact is the first torque generated.
It will consist of only pulses. Also, in the impact at the time of seating, if the tightening ability of the tool decreases, the tightening force that reaches at the time of seating decreases, so the peak value of the torque pulse that is generated secondly decreases,
The duration of the torque pulse is also shorter.

Therefore, by adopting the structure as claimed in claims 1 to 8, it is possible to detect a decrease in the tightening ability of the tool.

Further, in the invention described in claim 9,
Since the power source applied to the drive means is shut off when the abnormality determination means determines that the tightening ability is abnormal, it is possible to prevent the defective fastening product from flowing out during the screw tightening work.

Furthermore, in the invention described in claim 10, the abnormality determination means is provided with determination result output means for outputting a determination result when it is determined that the tightening ability is abnormal. In the invention, since the abnormality determination means is provided with the determination result display means for displaying the determination result when it is determined that the tightening ability is abnormal, the occurrence of the fastening failure when the fastening failure occurs due to the tightening ability decline. Will be recorded, and can be easily recognized by the operator.

[0059]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 In the first embodiment, using the peak torque value obtained from the detection result of the torque detecting means, the increase amount of the fastening force is calculated for each impact to sequentially obtain the fastening force, and the fastening force is obtained. In the impact type screw tightening device that shuts off the power source applied to the driving means when the force exceeds a predetermined value, the seating is determined from the detection result of the torque detecting means, and a plurality of impacts before each seating are included. When the interval between the first torque pulse and the second torque pulse generated in the torque pulse, that is, the free running time is detected, and this free running time does not reach the predetermined value When it is determined that the tightening capacity is abnormal, the power source applied to the drive means is shut off and the judgment is made. Outputs result, further illustrates an example in which to display.

1 to 3 show a first embodiment of the present invention, FIG. 1 is a block diagram of an impact type screw tightening device according to the first embodiment of the present invention, and FIG. 2 shows compressed air. Cross-sectional explanatory view of the impact wrench body used as a power source, FIG.
3 is a flowchart showing a calculation process.

First, in FIG. 1, the impact type screw tightener main body 1 is connected to a motor 2 and an output shaft 2a of the motor 2 so that the continuous torque of the motor 2 can be applied to the impact.
An impact torque generator 3 that converts the torque, a torque detector 5 that detects the torque acting on the output shaft of the impact torque generator 3, that is, the spindle 4, and a spindle 4
And a tightening socket (joint portion) 6 attached to the. The motor 2 may be of any type as long as it generates a driving force such as an electric motor or an air motor. Further, by selecting the shape of the tightening socket 6, it can be configured as a wrench or a nut / runner.

A control unit 7 is connected to the impact type screw tightener main body 1. The control device 7 includes a torque signal processing unit 7A that converts the signal from the torque detector 5 into a torque signal, a peak value processing unit 7B, a free running time processing unit 7C, a fastening force data / memory unit 7D,
Fastening force calculation unit 7E, power control unit 7F, output unit 7G
And a display section 7H.

Next, FIG. 2 shows a specific embodiment of the present invention and shows a cross section in the case of being configured as an impact wrench using compressed air as a power source.

In FIG. 2, 11 is an impact wrench main body (corresponding to the impact type screw tightener main body 1 in FIG. 1). Inside the impact wrench main body 11, an air supply unit 12 and an air motor are provided. A unit 13, a hydraulic pulse generator 14, and a torque detector 15 are provided. Then, in the air supply unit 12 into which air is introduced from the direction of arrow A,
An air passage 17 communicating with the air motor unit 13 is formed, and a main valve 18 and a switching valve 19 are provided in this order in the middle of the air passage 17.

The main valve 18 is opened by pulling the valve operating lever 20, and the switching valve 19 is opened by turning the rotation switching lever 21 to a predetermined rotation position. Further, the air motor unit 13 includes a rotary drive shaft 22 arranged in an eccentric cylinder, and the rotary drive shaft 22 is rotated by the compressed air acting on the vanes 23. Further, the hydraulic pulse generator 14 is composed of a main shaft 25 provided in a liner case 24 directly connected to the rotary drive shaft 22 of the air motor unit 13, and a driving blade 26 externally mounted on the main shaft 25. , Liner case 24
The inside is filled with oil liquid.

The main shaft 25 is provided with the inner surface of the liner case 24 and the driving blade 26 when there is no load above a certain level.
When the load exceeds a certain level, the hydraulic pressure acting on the inner surface of the driving blade 26 fluctuates and the shock is turned by the resistance of the air motor unit 13. It is like this. The tip of the main shaft 25 is shaped so as to be connected to a screw through a socket (a box wrench, which corresponds to the tightening socket 6 in FIG. 1), and this tip is screwed into a desired screw. The screw tightening can be done by adjusting to.

The torque detector 15 is arranged around the main shaft 25 and is composed of a pair of coils 15a and 15b fixed to the impact wrench body 11. The main shaft 25 is a pair of left and right groove rows 25 having different spiral angles.
It is made of a material having a magnetostrictive effect in which a and 25b are provided, and coils 15a and 15b are arranged facing these groove rows 25a and 25b. The torque acting on the main shaft 25 can be detected by the coils 15a and 15b.

Regarding the structure of the compressed air cutoff mechanism, a shut-off valve 29 for supplying / cutting off the compressed air sent from the direction of arrow A to the air motor section 13 is provided.
It is provided in the middle of an air passage 17 that connects the switching valve 19 and the air motor unit 13.

The control device 27 (corresponding to the control device 7 in FIG. 1) electrically connected to the impact wrench body 11 receives the signal output from the torque detection unit 15 as an input and outputs the torque signal. The peak torque signal processing unit (7A) and the peak value for each impact from the torque signal
A peak value processing unit (7B) for extracting a torque value, a free-running time processing unit (7C), and a "table about the dependence of the torque-engagement force conversion coefficient _{CTF on} the engagement force F" are recorded. Fastening force data memory unit (7D)
And a fastening force calculation unit (7E) and a power control unit (7F) that determines whether or not the calculated fastening force is within an appropriate range and sends an opening / closing control signal to the shut-off valve 29.
And an output unit (7G) for outputting a calculated fastening force value and a tightening ability decrease abnormality, and a display unit (7H) for displaying a calculated fastening force value and a tightening ability decrease abnormality.

FIG. 4 is a diagram showing an example of a "table for the dependence of the torque-engagement force conversion coefficient C _{TF on} the engagement force F" recorded in the engagement force data memory unit 7D.

As shown in FIG. 4, when an impact having a certain peak torque value is applied, and when the fastening force at that time is small, the increase amount of the fastening force due to the given impact becomes large, On the other hand, when the fastening force of a considerable level has already been generated, it can be seen that the amount of increase in the fastening force added by this is not large even with the impact of the same peak torque value. The specific values are bolts, fastened objects and impacts.
Different for each combination of wrenches. Therefore, such a table is prepared as a function for each combination of the impact wrench and the bolt and the object to be fastened, which is the object of use. Then, the fastening force calculation unit 7E calculates the fastening force based on the above peak torque value and this table, as will be described later.

Next, the operation of the first embodiment will be described based on the flow chart shown in FIG.

The compressed air sent from the air supply section 12 to the air motor section 13 via the shut-off valve 29 by pulling the valve operating lever 20 shown in FIG. 2 causes the air motor section 13 to move. The rotary drive shaft 22 rotates, and its rotational force is converted into a shocking rotational force in the hydraulic pressure pulse generation unit 14 and transmitted to the main shaft 25 to perform screw tightening work.

[0075] First, the value of the target engagement force _C F _C in step S1 of FIG. 3, also, the seating determination threshold free running time _S t _FR and clamping capacity drop abnormality determined in advance by experiments in step S2 and step S3 After setting the determination threshold free running time _SA t _FR , the impact number counter is reset at step S4 <count i = 0>, and the fastening force value up to that time is reset at step S5 <F (0 ) = 0>.

Here, the tightening ability deterioration abnormality determination threshold value free running time _SA t _FR is as _{follows with} respect to the average value t _FRA of the free running time at the impact before seating in the case of normal tightening and the standard deviation σ t _FR ,
The value may be set to _SA t _{FR ≈t FRA} −3σ _tFR .

Next, in step S6, screw tightening is started.

In steps S7 to S20,
Step S8 is the processing content in the free running time processing section 7C, step S11 is the processing content in the peak value processing section 7B, step S9, step S14, step S16 and step S17 are the processing content in the power control section 7F, and the other is the fastening. This is the processing content in the force calculation unit 7E.

Further, steps S7 to S10 form a loop, and the determination of abnormality in tightening ability deterioration and the seating determination are performed for each impact until the seating.

In this loop, first, step S7
After the count i is incremented by 1, the free running time t _FR is calculated based on the signal (torque signal) from the torque signal processing unit 7A in step S8.

Next, in step S9, it is determined whether or not the free running time t _FR is equal to or longer than the tightening ability deterioration abnormality determination threshold free running time _SA t _FR . If NO, that is, the tightening ability is abnormal, the process proceeds to step S17. After the cut-off command, the abnormal output command in step S18, and the abnormal display command in step S19 are issued, the process proceeds to step S20. As a result, the valve for the compressed air is closed and the fastening abnormality is output to the output unit 7G of the control device 7, and the display unit 7H.
Is displayed in.

[0082] On the other hand, if YES, that normally fastening is performed in step S9, the free running time _{t FR} is determined whether the sitting determination threshold free running time _S t _FR less in step S10, NO i.e. If not seated, the process returns to step S7 and step S10.
Repeat up to.

If YES at step S10,
That is, when it is determined that the person is seated, the process proceeds to a loop including steps S11 to S14 and step S15,
The fastening force is calculated for each impact.

In this loop, first, step S1
In No. 1, the peak torque value of impact (hereinafter referred to as the peak value of the first torque pulse generated in this embodiment) T _P (i) is calculated from the torque signal and stored.
At the time of sitting, the peak torque value T _P (i) may be obtained from the torque signal temporarily stored in step S8.

Next, in step S12, F (i-1)
The torque-fastening force conversion coefficient C _TF (i) in is calculated based on the table of the fastening force data / memory unit 7D. However, _CTF (i) = _CTF [F (i-1)].

Next, in step S13, the amount of increase in fastening force due to impact δF (i) = C _TF (i) × T _P
(I) is calculated and the fastening force F after this impact is calculated.
(I) is calculated by adding the increasing amount δF (i) to the fastening force up to that point, that is, the fastening force F (i-1) after the impact one time before. Therefore, F (i) =
F (i−1) + C _TF (i) × T _P (i).

[0087] Next, in step S14, after the fastening force after impact F (i) it is determined whether the target engagement force _C F _C above, the count i is increased by 1 at step S15 if NO , Return to step S11 and step S14
Repeat up to.

On the other hand, if YES in step S14,
The process proceeds to step S16, at which point a cut-off command is issued. This causes the compressed air valve to close.

Next, in step S20, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process returns to step S4 to perform the next screw tightening.

As a result, when the tightening capability of the tool is lowered, it is possible to judge the abnormality at the stage before seating and stop the tightening work, and prevent outflow of defectively tightened products.

Further, in the above description, the tightening ability deterioration abnormality determination is performed for each impact before sitting, but the average value of the free running time for each impact before sitting is determined at the time of sitting, and this average value is set to a predetermined value. Even if the system determines that the tightening ability is abnormal when the value is equal to or less than the value, it is possible to prevent the defective fastening product from flowing out in the same manner.

As described above, in this embodiment, the peak torque value obtained from the detection result of the torque detecting means is used to calculate the increase amount of the fastening force for each impact to sequentially obtain the fastening force. In an impact type screw tightening device that shuts off the power source applied to the drive means when the fastening force exceeds a predetermined value, the seating is determined from the detection result of the torque detection means, and a plurality of impacts before the seating are included. Of the torque pulse generated first and the second torque pulse generated in the second torque pulse, that is, the free running time is detected,
When the free running time does not reach the predetermined value, it is determined that the tightening ability is abnormal, and when it is determined that the tightening ability is abnormal, the power source applied to the drive means is shut off and the determination result is output. Furthermore, it is supposed to be displayed.

Therefore, in the impact type screw tightening device for controlling the power source applied to the drive means based on the fastening force obtained for each impact, the tightening of the tool is performed based on the detection result of the torque detecting means incorporated in the tool. It is possible to constantly monitor the decrease in capacity, and it is possible to respond even if the tightening capacity of the tool has deteriorated due to repeated use of the tool, etc., and it is possible to prevent the outflow of defective tightening products during screw tightening work. When a fastening failure occurs due to a decrease in performance, the occurrence of the fastening failure can be recorded and can be recognized by the operator.

Second Embodiment Next, FIGS. 5 and 6 show a second embodiment of the present invention, FIG. 5 is a block diagram, and FIG. 6 is a flow chart showing arithmetic processing.

In the second embodiment, using the peak torque value obtained from the detection result of the torque detecting means, the increase amount of the fastening force is calculated for each impact to obtain the fastening force sequentially.
In the impact type screw tightening device that shuts off the power source applied to the driving means when the fastening force exceeds a predetermined value, the seating is determined from the detection result of the torque detecting means and included in each impact before seating. If the peak value of the torque pulse that occurs first among a plurality of torque pulses is detected and the peak value of the torque pulse that occurs first does not reach the specified value, it is judged that the tightening capacity is abnormal. This is an example in which the determination is made, and when it is determined that the tightening capability is abnormal, the power source provided to the drive means is shut off, the determination result is output, and further displayed.

First, the structure will be described with reference to FIG.

In FIG. 5, the impact type screw tightener main body 31 includes a motor 32, an impact / torque generator 33, a main shaft 34, and a torque detector 35, as in the first embodiment.
And a tightening socket 36.

A control device 37 is connected to the impact type screw tightener main body 31. This control device 37
A torque signal processing unit 37A, a peak value processing unit 37B, a free running time processing unit 37C, which are the same as those in the first embodiment,
In addition to the fastening force data / memory unit 37D, the output unit 37G, and the display unit 37H, a fastening force calculation unit 37E and a power control unit 37F which are slightly different from those of the first embodiment are provided.

Next, the operation of the second embodiment will be described based on the flow chart shown in FIG.

First, in step S31, the target fastening force is set.
The value of _C F _C, also step S32 and step S
After setting the seating determination threshold free-running time _S t _FR and the tightening ability deterioration abnormality determination threshold peak torque _SA T _P, which have been obtained by experiments in advance in 33, the impact number counter is reset in step S34. Count i = 0>, and the value of the fastening force until then is reset in step S35 <F (0) = 0>.

Here, the tightening ability deterioration abnormality determination threshold peak torque _SA T _P is the torque that occurs first in the impact before seating in the case of normal tightening.
Average value T _PA of pulse peak values and standard deviation σ _TP
On the other hand, the value of _SA T _P ≈T _PA −3σ _TP may be set.

Next, in step S36, screw tightening is started.

In steps S37 to S51, the step S40 is the free running time processing unit 37.
Processing contents in C, step S38 and step S
42 is the processing content in the peak value processing part 37B, step S39, step S45, step S47 and step S48 are the processing content in the power control part 37F, and others are the processing content in the fastening force calculation part 37E.

Further, in steps S37 to S41, a loop is formed, and it is determined whether or not the tightening ability is abnormal and the seating is determined for each impact up to the seating.

In this loop, first, step S3
After incrementing the count i by 1 in 7, the step S38
In accordance with the signal (torque signal) from the torque signal processing unit 37A, the peak torque value (hereinafter, referred to as the peak value of the first torque pulse generated in this embodiment) T
_{Find P} (i).

Next, in step S39, it is determined whether or not the peak torque value T _P (i) is equal to or greater than the tightening capability lowering abnormality determination threshold peak torque _SA T _P , and if NO, that is, the tightening capability is abnormal. After the cut-off command, the abnormal output command in step S49, and the abnormal display command in step S50 are issued in step S48, the process proceeds to step S51. As a result, the valve for the compressed air is closed, and the fastening abnormality is output to the output unit 37G of the control device 37 and displayed on the display unit 37H.

On the other hand, if YES in step S39, that is, if the engagement has been normally performed, the free running time t _FR is calculated based on the torque signal in step S40.

Next, in step S41, the free running time t _FR is the seating determination threshold free running time _S.
It is determined whether or not t _FR or less, and if NO, that is, if the vehicle is not seated, the process returns to step S37 and repeats steps up to step S41.

If YES at step S41,
That is, when it is determined that the person is seated, the process proceeds to a loop including steps S42 to S45 and step S46,
The fastening force is calculated for each impact.

In this loop, first, step S4
In step 2, the impact peak torque value T _P (i) is obtained from the torque signal and stored. At the time of sitting, the peak torque value T _P (i) may be obtained from the torque signal temporarily stored in step S38 or step S40.

Next, in step S43, F (i-1)
The torque-engagement force conversion coefficient C _TF (i) in is calculated based on the table of the engagement force data memory unit 37D. However, _CTF (i) = _CTF [F (i-1)].

Then, in step S44, the amount of increase in the fastening force due to the impact δF (i) = C _TF (i) × T _P
(I) is calculated and the fastening force F after this impact is calculated.
(I) is calculated by adding the increasing amount δF (i) to the fastening force up to that point, that is, the fastening force F (i-1) after the impact one time before. Therefore, F (i) =
F (i−1) + C _TF (i) × T _P (i).

[0113] Next, in step S45, after the fastening force after impact F (i) it is determined whether the target engagement force _C F _C above, the count i is increased by 1 at step S46 if NO , And returns to step S42 to step S45.
Repeat up to.

On the other hand, if YES at step S45,
The process proceeds to step S47, at which point a cut-off command is issued. This causes the compressed air valve to close.

Next, in step S51, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process returns to step S34 to perform the next screw tightening.

As a result, when the tightening ability of the tool is lowered, it is possible to judge an abnormality at the stage before seating and stop the tightening work, and prevent the defective fitting from flowing out.

In the above description, the tightening ability deterioration abnormality determination is performed for each impact before seating, but the average value of the peak values of the first torque pulse generated for each impact before seating is determined. Even if a method of determining the tightening ability deterioration abnormality when this average value becomes equal to or less than a predetermined value when seated, similarly, it is possible to prevent defective fastening products from flowing out.

As described above, in the present embodiment, the peak torque value obtained from the detection result of the torque detecting means is used to calculate the increase amount of the fastening force for each impact to sequentially obtain the fastening force. In an impact type screw tightening device that shuts off the power source applied to the drive means when the fastening force exceeds a predetermined value, the seating is determined from the detection result of the torque detection means, and a plurality of impacts before the seating are included. The peak value of the torque pulse that occurs first among the torque pulses is detected, and if the peak value of the torque pulse that occurs first does not reach the specified value, it is determined that the tightening capacity is abnormal. When it is determined that the tightening ability has deteriorated, the power source applied to the drive means is shut off, and the determination result is output and further displayed. To have.

Therefore, in the impact type screw tightening device for controlling the power source applied to the driving means on the basis of the fastening force obtained for each impact, the tightening of the tool is carried out based on the detection result of the torque detecting means incorporated in the tool. It is possible to constantly monitor the decrease in capacity, and it is possible to respond even if the tightening capacity of the tool has deteriorated due to repeated use of the tool, etc., and it is possible to prevent the outflow of defective tightening products during screw tightening work. When a fastening failure occurs due to a decrease in performance, the occurrence of the fastening failure can be recorded and can be recognized by the operator.

Third Embodiment Next, FIGS. 7 and 8 show a third embodiment of the present invention, FIG. 7 is a block diagram, and FIG. 8 is a flow chart showing arithmetic processing.

The third embodiment is an impact type screw tightening for shutting off the power source applied to the driving means when the peak torque value obtained for each impact from the detection result of the torque detecting means becomes a predetermined value or more. In the device, the peak value of the second torque pulse generated among the plurality of torque pulses included in the impact during seating is detected from the detection result of the torque detection means, and the second torque pulse generated is detected. When the peak value of does not reach the predetermined value, it is determined that the tightening capacity deterioration is abnormal, and when it is determined that the tightening capacity deterioration is abnormal, the power source given to the drive means is shut off and the judgment result is output. , Shows an example of displaying.

First, the structure will be described with reference to FIG.

In FIG. 7, the impact type screw tightener main body 41 has a motor 42, an impact torque generator 43, a main shaft 44, and a torque detector 45, as in the first embodiment.
And a tightening socket 46.

A control device 47 is connected to the impact type screw tightener main body 41. This control device 47
Besides the torque signal processing unit 47A similar to that of the first embodiment, a peak value processing unit 47 slightly different from that of the first embodiment.
B, output unit 47G and display unit 47H, first and second
The power control unit 47F different from that of the above embodiment is provided.

Next, the operation of the third embodiment will be described based on the flow chart shown in FIG.

First, in step S61, the value of the target peak torque _C T _P is set, and in step S62, the tightening ability deterioration abnormality determination threshold peak torque _SA T _P determined in advance by experiment is set, and then the step The impact number counter is reset in S63 <count i =
0>.

Here, the tightening ability deterioration abnormality determination threshold peak torque _SA T _P is the average value T _PA of the peak values of the second torque pulse generated in the impact at the time of seating in the case of normal tightening. and relative standard deviation sigma _TP, may be set to the value of _{SA T P ≒ T PA -3σ TP} .

Next, in step S64, screw tightening is started.

In steps S65 to S75, steps S66 and S68 are processing contents in the peak value processing unit 47B, and others are processing contents in the power control unit 47F.

First, after incrementing the count i by 1 in step S65, the torque signal processing unit 4 is incremented in step S66.
Based on the signal (torque signal) from 7A, the peak torque value at the impact at the time of sitting (hereinafter referred to as the peak value of the second torque pulse generated in this embodiment) T _P (i) is obtained. .

Next, in step S67, it is determined whether or not the peak torque value T _P (i) is equal to or higher than the tightening ability lowering abnormality determination threshold peak torque _SA T _P , and NO, that is, the tightening ability is abnormal. For example, in step S72, a cut-off command, an abnormal output command in step S73, and an abnormal display command in step S74 are issued, and then the process proceeds to step S75. As a result, the valve for compressed air is closed, and the fastening abnormality is output to the output unit 47G of the control device 47 and displayed on the display unit 47H.

On the other hand, if YES in step S67, that is, if the engagement is normally performed, the process proceeds to the loop including step S68, step S69, and step S70 to detect the peak torque value.

In this loop, first, step S6
At 8, the peak torque value T _P (i) is obtained from the torque signal and stored. At the time of sitting, the peak torque value T _P (i) may be obtained from the torque signal temporarily stored in step S66.

Next, in step S69, it is determined whether or not the peak torque value T _P (i) is greater than or equal to the target peak torque _C T _P. If NO, the count i is incremented by 1 in step S70. Then, it returns to step S68 and repeats step S69.

On the other hand, if YES in step S69,
The process proceeds to step S71, at which point a cut-off command is issued. This causes the compressed air valve to close.

Next, in step S75, it is determined whether or not to end the process. If YES, the process ends as it is, and if NO, the process returns to step S63 to perform the next screw tightening.

As a result, when the tightening ability of the tool is lowered, it is possible to judge an abnormality when seated and stop the tightening work, and prevent defective tightening products from flowing out.

As described above, in the present embodiment, when the peak torque value obtained for each impact from the detection result of the torque detection means becomes a predetermined value or more, the impact that shuts off the power source applied to the drive means In the screw tightening device, the peak value of the second torque pulse generated among the plurality of torque pulses included in the impact at the time of seating is detected from the detection result of the torque detection means, and the second peak value is detected.
When the peak value of the torque pulse that occurs next does not reach the predetermined value, it is determined that the tightening capacity is abnormal, and when it is determined that the tightening capacity is abnormal, the power source applied to the drive means is shut off. The determination result is output and further displayed.

Therefore, in the impact type screw tightening device for controlling the power source applied to the drive means based on the peak torque value obtained for each impact, the tool is detected based on the detection result of the torque detection means incorporated in the tool. It is possible to constantly monitor the deterioration of the tightening capacity of the tool, and it is possible to deal with the case where the tightening capacity of the tool has deteriorated due to repeated use of the tool, etc. When a fastening failure occurs due to a reduction in the fastening capacity, the occurrence of the fastening failure can be recorded and can be recognized by the operator.

Fourth Embodiment Next, FIGS. 9 and 10 show a fourth embodiment of the present invention, FIG. 9 is a block diagram, and FIG. 10 is a flow chart showing arithmetic processing.

The fourth embodiment is an impact type screw tightening for shutting off the power source applied to the driving means when the peak torque value obtained for each impact from the detection result of the torque detecting means exceeds a predetermined value. In the device, the duration of the torque pulse at the impact at the time of sitting is detected from the detection result of the torque detection means, and if the duration of this torque pulse does not reach the predetermined value, it is determined that the tightening ability is abnormal. An example is shown in which, when it is determined that the tightening ability is abnormal, the power source applied to the drive means is shut off, the determination result is output, and further displayed.

First, the structure will be described with reference to FIG.

In FIG. 9, the impact type screw tightener main body 51 has a motor 52, an impact torque generator 53, a main shaft 54, and a torque detector 55, as in the first embodiment.
And a tightening socket 56.

A control device 57 is connected to the impact type screw tightener main body 51. This control device 57
In addition to the torque / pulse duration processing unit 57I and the torque signal processing unit 57A similar to that of the first embodiment, a peak value processing unit 57B, an output unit 57G and a display unit 57H similar to those of the third embodiment, A power control unit 57F different from those of the first, second and third embodiments is provided.

Next, the operation of the fourth embodiment will be described based on the flow chart shown in FIG.

First, in step S81, the value of the target peak torque _C T _P is set, and in step S82, the tightening ability deterioration abnormality determination threshold duration time previously obtained by experiment is determined.
After setting each _SA W _P , the impact number counter is reset in step S83 <count i = 0
>.

[0147] Here, tightening capacity reduction abnormality determination threshold duration _SA W _P, relative to the average value W _PA and standard deviation sigma _{W P} of the duration of the torque pulses during seating of the case of tightening a normal , _SA W _P ≈W _PA −3σ _WP .

Next, in step S84, screw tightening is started.

In steps S85 to S95, step S86 is the torque / pulse duration processing unit 5.
7I, the processing content of the peak value processing unit 57B in step S88, and the other processing content in the power control unit 57F.

First, after incrementing the count i by 1 in step S85, the torque signal processing unit 5 is incremented in step S86.
Based on the signal (torque signal) from 7A, the torque pulse duration W _P at the impact during sitting is determined.

Next, in step S87, it is determined whether or not the torque / pulse duration W _P is equal to or greater than the tightening ability deterioration abnormality determination threshold torque / pulse duration _SA W _P , and NO.
That is, if the tightening capability is abnormal, the process proceeds to step S92, a cut-off command, an abnormal output command in step S93, and an abnormal display command in step S94 are issued, and then the process proceeds to step S95. As a result, the valve for compressed air is closed, and the fastening abnormality is output to the output unit 57G of the control device 57 and displayed on the display unit 57H.

On the other hand, if YES in step S87, that is, if the engagement is normally performed, the process proceeds to the loop including step S88, step S89, and step S90 to detect the peak torque value.

In this loop, first, step S8
In step 8, a peak torque value (hereinafter, referred to as the peak value of the second torque pulse generated in this embodiment) T _P (i) is calculated from the torque signal and stored. At the time of sitting, the peak torque value T is calculated from the torque signal temporarily stored in step S86.
_It suffices to find _P (i).

Next, in step S89, it is determined whether or not the peak torque value T _P (i) is greater than or equal to the target peak torque _C T _P. If NO, the count i is incremented by 1 in step S90. After that, the process returns to step S88 to repeat step S89.

On the other hand, if YES in step S89,
The process proceeds to step S91, at which point a cut-off command is issued. This causes the compressed air valve to close.

Next, in step S95, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process returns to step S83 to tighten the next screw.

As a result, when the tightening ability of the tool is lowered, it is possible to judge the abnormality at the time of sitting and stop the tightening work, and prevent outflow of defective fastening products.

As described above, in the present embodiment, when the peak torque value obtained for each impact from the detection result of the torque detection means becomes a predetermined value or more, the impact that shuts off the power source applied to the drive means In the automatic screw tightening device, the duration of the torque pulse at the impact at the time of sitting is detected from the detection result of the torque detection means, and if the duration of this torque pulse does not reach the predetermined value, it is determined that the tightening ability is abnormal. When it is determined that the tightening capability is abnormal, the power source applied to the drive means is shut off, and the determination result is output and further displayed.

Therefore, in the impact type screw tightening device for controlling the power source applied to the drive means based on the peak torque value obtained for each impact, the tool is detected based on the detection result of the torque detection means incorporated in the tool. It is possible to constantly monitor the deterioration of the tightening capacity of the tool, and it is possible to deal with the case where the tightening capacity of the tool has deteriorated due to repeated use of the tool, etc. When a fastening failure occurs due to a reduction in the fastening capacity, the occurrence of the fastening failure can be recorded and can be recognized by the operator.

[0160]

As described above, according to the first aspect of the invention, the calculation means detects the tightening capacity decrease of the impact type screw tightener main body based on the detection result of the torque detection means. By the way,
According to the second aspect of the present invention, when the tightening capacity detected by the computing means is reduced to a specified value or less, the abnormality determining means determines that the tightening capacity is abnormal, thereby reducing the tightening capacity of the tool. By being able to constantly monitor, it is possible to sufficiently cope with the deterioration of the tightening ability of the tool due to repeated use of the tool, and it is possible to prevent the outflow of defective tightening products during screw tightening work. The effect is brought.

In the invention described in claim 3,
The impact type screw tightening device according to claim 2,
The seating is determined from the detection result of the torque detecting means, and a plurality of torques included in each impact before seating are detected.
Torque pulse generated first in the pulse and second
In addition, by detecting the occurrence interval of the torque pulse that occurs the second time, that is, the free running time, and determining that the tightening capacity deterioration is abnormal when this free running time does not reach the predetermined value, In the invention according to claim 4, in the impact type screw tightening device according to claim 2, the seating is determined from the detection result of the torque detecting means, and among the plurality of torque pulses included in each impact before seating. By detecting the peak value of the torque pulse that occurs first, and determining that the tightening capacity deterioration is abnormal when the peak value of the torque pulse that occurs first does not reach the specified value. Further, in the invention according to claim 5, in the impact type screw tightening device according to claim 2, torque detecting means is provided. From the detection result, the peak value of the second torque pulse generated among the plurality of torque pulses included in the seating impact is detected, and the peak value of the second torque pulse generated is set to a predetermined value. By determining that the tightening ability is abnormal when it does not reach, the detection result of the torque detecting means in the impact type screw tightening device according to claim 2 is further determined. From this, the duration of the torque pulse at the impact at the time of sitting is detected, and if the duration of this torque pulse does not reach the specified value, it is judged that the tightening ability has deteriorated. Based on the detection result of the torque detection means, it is possible to detect a reduction in the tightening ability of the tool, and by repeated use of the tool, etc. It is clamping capability results in markedly excellent effect that it is possible to sufficiently cope with the case of decrease.

Further, in the invention described in claim 7,
Using the peak torque value obtained from the detection result of the torque detection means, the increase amount of the fastening force is calculated for each impact to sequentially obtain the fastening force, and the fastening force obtained for each impact becomes a predetermined value or more. By cutting off the power source applied to the drive means at the time point, and in the invention according to claim 8, the peak torque value obtained for each impact from the detection result of the torque detection means is a predetermined value. By shutting off the power source applied to the driving means at the time point described above, the impact type screw tightening device controls the power source applied to the driving means based on the fastening force obtained for each impact. Even one
Even if the power source applied to the drive means is controlled based on the peak torque value obtained for each impact, the tightening ability of the tool is determined based on the detection result of the torque detection means incorporated in the tool. It is possible to detect the decrease, and it is possible to sufficiently cope with the case where the tightening ability of the tool is deteriorated due to the repeated use of the tool or the like.

Further, in the invention described in claim 9, the power source applied to the drive means is shut off when it is determined that the tightening ability is abnormally reduced.
In the screw tightening work, it is possible to prevent the outflow of defective fastening products, which is a remarkably excellent effect.

Furthermore, in the invention described in claim 10, the determination result is output when it is determined that the tightening capability is abnormal, and in the invention described in claim 11, the tightening capability is By displaying the judgment result when it is judged that the deterioration is abnormal, it is possible to record the occurrence of the fastening failure when the fastening failure occurs due to the deterioration of the fastening capacity, and the operator can easily recognize it. It has a remarkably excellent effect of being able to do.

[Brief description of drawings]

FIG. 1 is a block diagram of an impact type screw tightening device according to a first exemplary embodiment of the present invention.

FIG. 2 is an explanatory sectional view in the case of being configured as an impact wrench using compressed air as a power source.

FIG. 3 is a flowchart showing a calculation process of the first embodiment.

FIG. 4 is an explanatory diagram showing an example of a “table regarding dependence of torque-fastening force conversion coefficient on fastening force” recorded in a fastening force data memory unit.

FIG. 5 is a block diagram of an impact type screw fastening device according to a second exemplary embodiment of the present invention.

FIG. 6 is a flowchart showing a calculation process of the second embodiment.

FIG. 7 is a block diagram of an impact type screw fastening device according to a third exemplary embodiment of the present invention.

FIG. 8 is a flowchart showing a calculation process of the third embodiment.

FIG. 9 is a block diagram of an impact type screw fastening device according to a fourth exemplary embodiment of the present invention.

FIG. 10 is a flowchart showing a calculation process of a fourth embodiment.

FIG. 11 is a schematic explanatory diagram of changes in the torque waveform of the impact from when the impact starts to when the user sits down.

FIG. 12: Free-running time at impact before seating and peak value of torque pulse firstly generated, peak value of torque pulse firstly generated at impact at seating and duration of torque pulse FIG. 4 is an explanatory diagram of changes in final reaching fastening force with repeated use.

FIG. 13 is an explanatory sectional view of an impact wrench showing an example of the prior art.

FIG. 14 is a flowchart showing a calculation process when controlling the fastening force of a screw in the prior art.

[Explanation of symbols]

1, 31, 41, 51 Impact type screw tightener main body 2, 32, 42, 52 Motor (driving means) 3, 33, 43, 53 Impact torque generator (driving means) 4, 34, 44, 55 Spindle 5 , 35, 45, 55 Torque detector (torque detecting means) 6, 36, 46, 56 Tightening socket (joint portion) 7, 37, 47, 57 Control device (control means) 7A, 37A, 47A, 57A Torque signal processing Part 7B, 37B, 47B, 57B Peak value processing part 7C, 37C Free running time processing part 7D, 37D Engaging force data memory part 7E, 37E Engaging force computing part 7F, 37F, 47F, 57F Power control part 7G, 37G, 47G, 57G Output section 7H, 37H, 47H, 57H Display section 57I Torque pulse duration processing section 11 Impact wrench book (Impact screw tightener body) 13 Air motor unit (driving means) 14 Hydraulic pulse generator (driving means) 15 torque detecting unit (torque detecting means) 25 spindle 27 controller (control means)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Teru Fukumura 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd.

Claims (11)

[Claims] 1. A drive means having a pulse component in a drive output, a spindle having a screw joint at one end and tightening the screw driven by the drive means, and torque detection for detecting a torque change of the spindle. An impact type screw tightener main body having means, a calculation means for detecting a tightening capability decrease of the impact type screw tightener main body based on the detection result of the torque detection means, and a target based on the detection result of the torque detection means An impact-type screw tightening device comprising: a control unit that controls a power source applied to the drive unit to realize a fastening force. 2. The impact type screw tightening device according to claim 1, further comprising abnormality determining means for determining a tightening ability deterioration abnormality when the tightening ability detected by the computing means falls below a specified value. Characteristic impact type screw tightening device. 3. The impact type screw tightening device according to claim 2, wherein the computing means also has a function of determining seating from a detection result of the torque detecting means, and the torque is detected in order to detect a decrease in tightening ability. From the detection result of the detection means, the generation interval between the torque pulse generated first and the torque pulse generated second among the plurality of torque pulses included in each impact before seating, that is, free running time The impact type screw having a function of detecting abnormality, and the abnormality determining means has a function of determining that the tightening ability is abnormal when the free running time does not reach a predetermined value. Fastening device. 4. The impact type screw tightening device according to claim 2, wherein the computing means also has a function of determining seating from a detection result of the torque detecting means, and the torque is detected in order to detect a decrease in tightening ability. The abnormality determining means has a function of detecting a peak value of a torque pulse generated first among a plurality of torque pulses included in each impact before seating based on the detection result of the detecting means. An impact type screw tightening device characterized by having a function of determining that the tightening capability is abnormal when the peak value of the torque pulse generated first does not reach a predetermined value. 5. The impact type screw tightening device according to claim 2, wherein the calculating means detects a plurality of torque pulses included in the impact at the time of sitting from the detection result of the torque detecting means in order to detect a decrease in tightening ability. The abnormality determining means has a function of detecting a peak value of a torque pulse secondly generated, and the abnormality determining means stops the peak value of the torque pulse secondly generated from reaching a predetermined value. The impact type screw tightening device is characterized in that it has a function of determining that the tightening ability is abnormal when the screw tightening occurs. 6. The impact type screw tightening device according to claim 2, wherein the calculating means detects the duration of the torque pulse at the impact at the time of sitting from the detection result of the torque detecting means in order to detect a decrease in the tightening ability. The abnormality determining means has a function of determining that the tightening ability is abnormal when the duration of the torque pulse does not reach a predetermined value. Impact type screw tightening device. 7. The impact type screw tightening device according to any one of claims 1 to 6, wherein the computing means uses the peak torque value obtained from the detection result of the torque detecting means to determine the fastening force for each impact. The control means also has a function of calculating the increase amount and sequentially obtaining the fastening force, and the control means controls the power source applied to the driving means when the fastening force obtained for each impact exceeds a predetermined value. An impact-type screw tightening device characterized by having a shutoff function. 8. The impact type screw tightening device according to any one of claims 1 to 6, wherein the peak torque value obtained for each impact from the detection result of the torque detection means by the control means is a predetermined value or more. The impact-type screw tightening device is characterized in that it has a function of shutting off a power source applied to the drive means at the point of time. 9. The impact type screw tightening device according to any one of claims 2 to 8, wherein the control means controls a power source applied to the driving means when the abnormality determining means determines that the tightening ability is abnormal. Impact type screw tightening device, which also has the function of shutting off. 10. The impact type screw tightening device according to any one of claims 2 to 9, further comprising a judgment result output means for outputting a judgment result when the abnormality judging means judges that the tightening ability is abnormal. Characteristic impact type screw tightening device. 11. The impact type screw tightening device according to claim 2, further comprising a judgment result display means for displaying a judgment result when the abnormality judging means judges that the tightening ability is abnormal. Characteristic impact type screw tightening device.