JPH07237145A - Impact type screw tightening device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an impact type screw tightening device that can accurately calculate the actual tightening force. [Structure] Driving means 10 having pulse component in driving output
2 and 103, a main shaft 104 that tightens a screw by being driven by a driving unit, and a torque detection unit 101 that detects a torque change of the main shaft, and an impact type screw tightener main body 100, and when calculating a fastening force. In addition, the fastening force obtained by the first impact is calculated as a function of parameters (free running time) other than the peak torque value included in the waveform of the impact torque, and the fastening force increase in the second and subsequent impacts. Is a peak-torque value of impact and a torque-fastening force conversion coefficient obtained as a function of fastening force in advance, and a control means 120 configured to calculate the product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention utilizes impact force to
A screw tightening device that performs screw tightening work, such as 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 tightening torque, there is, for example, a device described in Japanese Utility Model Application No. 3-12370. FIG. 24 is a cross-sectional view of the above device. In FIG. 24, the main shaft 15 is made of a material having a magnetostrictive effect. Then, a change in torque is detected by detecting a change in magnetic permeability on the surface of the main shaft 15 that accompanies a torque pulse generated during screw tightening as a change in inductance of the detection coils 26a and 26b of the torque detection unit 11. Then, when the detected torque reaches a value within a predetermined range, the shut-off valve 12 is closed by the control signal from the control device 110, and the air motor unit 13 is closed.
The compressed air is shut off, and the drive of the hydraulic pressure pulse generator 14 and the main shaft 15 is stopped. However, in the case of screw tightening with a torque wrench such as a taper beam wrench, the tightening torque and the fastening force generated at the fastening portion are in a proportional relationship, but in the impact wrench as described above, the The peak value of torque pulse (hereinafter abbreviated as peak torque value) is not proportional to the fastening force. For example, the fastening force increases even when an impact with a smaller peak torque value than the immediately preceding impact occurs. As a result of experiments, it was found that such a phenomenon frequently occurs. Thus, the peak torque value of impact cannot be said to correspond to the fastening force on a one-to-one basis, so even if this peak torque value is accurately detected, the fastening force cannot be detected accurately. Therefore, even if the shut-off valve is cut off based on this, the fastening force is not accurately controlled. As described above, in the conventional device, the fastening force cannot be accurately detected, so that there is a problem in that it is difficult to accurately control the fastening force to a desired fastening force.

In order to solve the above problems, the applicant has
An application has already been filed for a device that calculates the amount of increase in fastening force using the peak torque value for each impact during screw tightening (Japanese Patent Application No. 4-254028: unpublished). FIG. 25 is a flowchart of calculation in the device. The mechanical portion is the same as that shown in FIG. This device
As shown in FIG. 25, the increase amount of the fastening force is calculated by using the peak torque value for each impact during screw tightening, and the fastening force is obtained by sequentially adding the increased amount, and the value is the predetermined fastening force. The target fastening force is obtained by shutting off the compressed air supplied to the impact wrench at the time when the pressure reaches the point.

A detailed description will be given below with reference to FIG.
First, after setting the value of the target fastening force cFc in step S301, the impact number counter is reset in step S302 <count i = 0>, and further in step S30.
The value of the fastening force up to that point is reset with 3. <F (0) =
0>. Next, in step S304, screw tightening is started. Further, steps S305 to S309 form a loop, and the fastening force is calculated for each impact. First, after incrementing the count i by 1 in step S305, the peak torque value T _P (i) of the impact is obtained and stored from the signal of the torque sensor in step S306. Next, in step S307, the torque-engagement force conversion coefficient _CTF (i) at F (i-1) is calculated based on the table of the engagement force data / memory unit. However, C
_TF (i) = C _TF [F (i-1)]. Next, step S30
8, the tightening force increase due to impact δF (i) =
C _TF (i) × T _P (i) is calculated, and the fastening force F (i) after this impact is used as the fastening force up to that point, that is, the fastening force F (i-1) after the previous impact. It is calculated by adding the increment δF (i). Therefore, F (i) = F (i−1) + C _TF (i) × T _P (i). Next, in step S309, the fastening force F after impact is applied.
It is determined whether or not (i) is equal to or greater than the target fastening force cFc, and if NO, the process returns to step S305 to repeat step S309. On the other hand, if YES in step S309,
The process proceeds to step S310, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, in step S311, 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 S302 to perform the next screw tightening. Although the above-mentioned conventional example and the description of the prior art by the applicant have been described by taking the impact wrench as an example, the same applies to the impact type nut runner and the like.

[0005]

As described above, as shown in FIG.
In the conventional device shown in (1), the fastening force cannot be accurately detected, so that there is a problem that it is difficult to accurately control the fastening force to a desired fastening force. Further, in the prior invention of the present applicant made to solve the above problems, the fastening force can be detected. But,
Although the fastening force obtained by the first impact is greatly affected by the seated state immediately before that, the fastening force is simply expressed as the peak torque value of the impact and the torque-fastening force when the fastening force is zero. Since it is calculated as the product of the conversion coefficient, a large calculation error may occur at this stage. For example, when seating at the first impact like a normal nut, the fastening force reached at this impact may vary greatly, so the accuracy of estimating the fastening force after that will decrease, and the final fastening There was a problem that the accuracy of the force calculation was reduced.

The present invention has been made in order to solve the problems of the prior art as described above and to further improve the prior art of the present applicant, and it is possible to accurately calculate the actual fastening force and to improve the accuracy. An object of the present invention is to provide an impact type screw tightening device capable of performing a good screw tightening work.

[0007]

In order to achieve the above object, the present invention is constructed as described in the claims. That is, in the invention according to claim 1, a drive means having a pulse component in the drive output, a joint part with a screw at one end, and a main shaft for tightening the screw when driven by the drive means, An impact type screw tightener main body having a torque detecting means for detecting a torque change of the main shaft, and an increasing amount of the fastening force is calculated for each impact based on the detection result of the torque detecting means to sequentially obtain the fastening force. , The power source applied to the drive means is controlled so as to realize the target fastening force, and the fastening force obtained by the first impact when the fastening force is calculated corresponds to the occurrence of impact. Of the parameters included in the waveform of the torque pulse, it is calculated as a function of the parameters other than the peak value of the torque pulse, and the second and subsequent impact parameters are calculated. The increasing amount of the tightening force in (1) is configured to include a control unit that calculates the product of the peak value of the torque pulse and the torque-fastening force conversion coefficient that is previously obtained as a function of the tightening force. . The above-described impact type screw tightener main body corresponds to, for example, the impact type screw tightener main body 100 (details are shown in FIG. 2) in the embodiment shown in FIG. 1, which will be described later. Similarly, the driving means is a motor 102 and a torque. Corresponding to the portion of the pulse generator 103, the spindle and the torque detecting means are respectively the spindle 104 and the torque detector 10.
Equivalent to 1. Further, the control means is, for example, as shown in FIG.
It corresponds to the control device 120 in the embodiment.

Further, in the invention described in claim 2,
The impact type screw tightening device according to claim 1,
As a parameter included in the waveform of the torque pulse corresponding to the occurrence of the impact, the torque pulse first generated and the torque second generated among the plurality of torque pulses generated for each impact by the drive unit are included. The interval with the pulse, that is, the free running time is detected, and the fastening force obtained by the first impact is calculated as a function of the above free running time. Note that this configuration corresponds to, for example, the embodiment of FIG. 1 described later.

Further, in the invention described in claim 3,
The impact type screw tightening device according to claim 1,
As a parameter included in the waveform of the torque pulse corresponding to the occurrence of the impact, a constant sampling is performed from the rising edge of the torque pulse generated first among the plurality of torque pulses generated for each impact by the driving means. The number of data showing a value equal to or more than a predetermined torque value when sampling a predetermined number of data at intervals is detected, that is, the number of extracted data is detected, and the fastening force obtained by the first impact is extracted as described above. It is configured to operate as a function of the number of data. Note that this configuration corresponds to, for example, the embodiment shown in FIG. 7 described later.

Further, in the invention described in claim 4,
A drive means having a pulse component in the drive output, a joint at one end with a screw, which tightens the screw by being driven by the drive means, and torque detection means for detecting a torque change of the spindle, Using the impact type screw tightener main body having, and the peak value of the torque pulse obtained from the detection result of the torque detection means, the amount of increase in the fastening force is calculated for each impact to sequentially obtain the fastening force,
The torque source is controlled to control the power source applied to the drive means so as to achieve the target fastening force, and the torque obtained by the first impact during the calculation of the fastening force is the peak of the torque pulse. Value, the torque-fastening force conversion coefficient that was previously obtained as a function of the fastening force, and the parameters included in the waveform of the torque pulse corresponding to the occurrence of impact, other than the peak value of the torque pulse. Control means for calculating the amount of increase in the fastening force at the second and subsequent impacts as the product of the peak value of the torque pulse and the torque-fastening force conversion factor. It is configured to include. In addition, this configuration is
For example, this corresponds to the embodiment shown in FIG.

According to the invention of claim 5,
The impact type screw tightening device according to claim 4,
As a parameter included in the waveform of the torque pulse corresponding to the occurrence of the impact, the torque pulse first generated and the torque second generated among the plurality of torque pulses generated for each impact by the drive unit are included. The distance from the pulse, that is, the free running time is detected, and the correction coefficient when calculating the fastening force obtained by the first impact is calculated as a function of the above free running time. Note that this configuration corresponds to, for example, the embodiment of FIG. 12 described later.

According to the invention of claim 6,
The impact type screw tightening device according to claim 4,
As a parameter included in the waveform of the torque pulse corresponding to the occurrence of the impact, a constant sampling is performed from the rising edge of the torque pulse generated first among the plurality of torque pulses generated for each impact by the driving means. When calculating the fastening force obtained by the above first impact by detecting the number of data showing a value equal to or more than a predetermined torque value when sampling torque data by a predetermined number of data at intervals, that is, the number of extracted data The correction coefficient is configured to be calculated as a function of the number of extracted data. Note that this configuration corresponds to, for example, the embodiment of FIG. 16 described later.

[0013]

In the invention described in claim 1, the fastening force obtained by the first impact when the fastening force is calculated is the torque among the parameters included in the waveform of the torque pulse corresponding to the occurrence of the impact.・ Calculated as a function of parameters other than the peak value of the pulse (peak torque value), and the amount of increase in the fastening force at the second and subsequent impacts is obtained as a function of the peak torque value and the fastening force in advance. It is configured to be calculated as a product of the torque-fastening force conversion coefficient. Torque pulse (hereinafter referred to as impact
Parameters other than the peak torque value among parameters included in the waveform (abbreviated as torque) include the free running time as described in claim 2 and the number of extracted data as described in claim 3. The free-running time is the interval between the first torque pulse and the second torque pulse of the plurality of torque pulses generated for each impact, during which the nut and bolt are Free running state. Also,
The number of extracted data is a predetermined value when a predetermined number of data are sampled at a fixed sampling interval from the rising of the first torque pulse of the plurality of torque pulses generated for each impact. Is the number of data indicating a value equal to or greater than the torque value (extraction determination threshold torque), and is, for example, as shown in FIG. As will be described later in detail, the fastening force obtained at the first impact strongly depends on the seated state immediately before that, and this seated state is the first impact.
It is reflected in parameters such as the free running time and the number of extracted data included in the torque waveform. Therefore, by calculating the fastening force obtained by the first impact as a function of the above parameters, the initial fastening force, which was difficult in the past, can be accurately obtained, and the accuracy of the overall fastening force calculation can be improved. Since it can be improved, it is possible to precisely tighten the screw up to the target fastening force.

Next, in the invention described in claim 4,
When calculating the fastening force, the fastening force obtained by the first impact should be converted into the impact peak torque value, the torque-fastening force conversion coefficient previously obtained as a function of the fastening force, and the impact torque waveform. It is calculated as a product with a correction coefficient given as a function of a parameter other than the included peak torque value. Thus, in calculating the fastening force obtained by the first impact, by adding a correction coefficient given as a function of a parameter other than the peak torque value included in the waveform of the impact torque, the claim As in the case of 1, the seating state immediately before the first impact can be reflected, so that the initial fastening force can be accurately obtained. The parameters included in the waveform of the impact torque include the free-running time as described in claim 5 and the number of extracted data as described in claim 6, which means that the parameters are included in the claims 2 and 3. Is the same as.

Now, the fastening process for the period from the start of the supply of the compressed air until the fastening force increases due to the first impact will be described in detail. FIG. 21 shows the torque when the bolt is rotated by the impact type screw tightening device to tighten the screw, and the rotation angle of the bolt,
It is the figure which showed the change of fastening force typically. As shown in FIG. 21, focusing on the rotation of the bolt, the process in which the bolt starts to rotate with the start of the supply of compressed air and the rotational speed increases, and the process in which the bolt rotates steadily at a certain rotational speed , The process in which the rotation speed of the bolt decreases with seating, the process in which the bolt stops, and the process in which the bolt re-rotates due to the first impact torque and the bolt decelerates again and then stops. First, in the process of (1), since the frictional resistance on the thread surface of the bolt is smaller than the frictional resistance between the inner surface of the hydraulic pulse generator liner case and the driving blade described later, the air motor, the liner case of the hydraulic pulse generator, The main shaft and the bolt rotate together, and the main shaft detects a torque having a long duration and a small absolute value for accelerating the bolt. Next, in the process of
Similar to the process of (1), the air motor, the liner case of the hydraulic pulse generator, the main shaft and the bolt rotate together, but no torque is detected on the main shaft. Next, in the process of, because the frictional resistance of the seat surface increases with the seating, the bolt decelerates, and the torque is detected again on the main shaft, and a slight tightening force is generated. .
If the frictional resistance between the seating surface and the threaded surface becomes larger than the frictional resistance between the inner surface of the liner case and the driving blade, the inner surface of the liner case and the driving blade will slip, further reducing the speed of the bolt and spindle. Then, the liner case and the air motor continue to rotate, and the liner case rotates relative to the main shaft. Next, in the process of, the liner case rotates against the stopped spindle, and the impact torque is generated by the mechanism described later, and the bolt rotates against the friction resistance of the seat surface and the thread surface. The torque rapidly increases until it reaches the maximum static friction torque. That is, the first torque pulse is generated. Next, in the process of, when the torque reaches the maximum static friction torque, the bolt temporarily starts to rotate in the free running state, and the torque decreases rapidly,
The fastening force increases rapidly. At this time, the liner case and the main shaft rotate together, but the rotational speed of the main shaft gradually decreases due to the dynamic friction of the seat surface and the screw surface.
Immediately before stopping, the liner case rotates faster than the main shaft, and the second torque pulse is detected. The relative rotation angle between the main shaft and the liner case from the rising of the first torque pulse to the end of the second torque pulse is about 2 to 3 degrees. In the above process, the time Fr from when the torque drops to 0 to when it rises again is the free running time.

Further, FIG. 22 shows M8 concerning the relationship between the parameters included in the waveform of the first impact torque, that is, the peak torque value, the free running time and the number of extracted data, and the fastening force obtained at the first impact.
FIG. 4A is a characteristic diagram of the bolt of FIG. 3, where (a) shows the peak torque value, (b) shows the free running time, and (c) shows the number of extracted data. As shown in FIG. 22, it can be seen that the fastening force obtained at the first impact is greater as the impact peak torque value is smaller, the free running time is longer, and the number of extracted data is smaller. It is considered that this is related to the above process, that is, the extent to which the seat surface rubs between the bolt and the body to be fastened during seating immediately before the first impact, and the friction coefficient at the contact surface between the two decreases. When the seat surface is strongly rubbed during seating, both the seat surfaces of the bolt and the object to be fastened are scraped to reduce the friction coefficient, but the weaker the rubbing, the less the friction coefficient is reduced. For example, when the rotation speed of the bolt in the above process is high, the coefficient of friction is greatly reduced. Therefore, the maximum static friction torque or peak
The torque value becomes smaller, the free running time becomes longer, and the fastening force becomes larger.

Further, as shown in the schematic characteristic diagram of FIG. 23, the number of extracted data is the number of data showing a value equal to or larger than a predetermined extraction judgment threshold torque among the sampling values of torque. Therefore, the number of extracted data becomes 0 during the free running time when the torque value is 0. Therefore, the longer the free running time, the smaller the number of extracted data. Therefore, the smaller the number of extracted data, the larger the fastening force. As mentioned above, the fastening force obtained at the first impact strongly depends on the seating state immediately before that, and this seating state is such as the free running time and the number of extracted data included in the waveform of the first impact torque. It is reflected in the parameter. Therefore, by configuring as described in claims 1 to 6, it is possible to accurately detect the fastening force obtained at the first impact.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. In the first embodiment, the free running time is detected as a parameter included in the waveform of the first impact torque, and the fastening force obtained by the first impact is calculated as a function of the above free running time when the fastening force is calculated. It is an example configured to calculate as. 1 to 3 are diagrams of a first embodiment of the present invention, FIG. 1 is a block diagram of the present invention, FIG. 2 is a sectional view of an impact wrench body using compressed air as a power source, and FIG. It is a flowchart showing. First, in FIG. 1, an impact type screw tightener main body 100 is connected to a motor 102 and an output shaft of the motor 102, and is a torque pulse generator that converts a continuous rotational force of the motor 102 into a torque pulse. 103 and
Output shaft of the torque pulse generator 103, that is, the main shaft 1
Torque detector 10 for detecting the torque acting on 04
1 and a tightening socket (joint portion) 105 attached to the main shaft 104. The motor 102 may be of any type as long as it can generate a driving force such as an electric motor or an air motor. Further, by selecting the shape of the tightening socket 105, it can be configured as a wrench or a nut / runner. The impact type screw tightener main body 100 includes a control device 12
0 is connected. The control device 120 converts a signal from the torque detector 101 into a torque signal, a torque signal processing unit 121, a peak value processing unit 122, a free running time processing unit 128, and a fastening force data / memory unit 123. , Fastening force calculation unit 124, and power control unit 12
It is composed of 5 and.

Next, FIG. 2 is a specific embodiment of the present invention and shows a sectional view in the case of being constructed as an impact wrench using compressed air as a power source. In FIG. 2, 10 is an impact wrench body (corresponding to 100 in FIG. 1)
The impact wrench body 10 is provided with an air supply unit 16, an air motor unit 13, a hydraulic pressure pulse generation unit 14, and a torque detection unit 11. An air passage 17 communicating with the air motor unit 13 is formed in the air supply unit 16, and a main valve 18 and a switching valve 19 are provided in this order in the air passage 17. Main valve 1
8 is opened by pulling the valve operating lever 20,
The switching valve 19 is opened by turning the rotation switching lever 21 to a predetermined rotation position. 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. The hydraulic pulse generator 14 is connected to the rotary drive shaft 22 of the air motor unit 13 and is directly connected to the liner case 2.
The main shaft 15 is provided inside the main shaft 15, and the driving blade 25 is mounted on the main shaft 15. The liner case 24 is filled with oil liquid. The main shaft 15 rotates together with the rotary drive shaft 22 of the air motor section 13 by the resistance of the inner surface of the liner case 24 and the driving blade 25 when there is no load above a certain level, and the relief valve 28 when there is a load above a certain level. The hydraulic pressure acting on the inner surface of the driving blade 25 via the shaft fluctuates to shockly rotate. This spindle 15
The tip end of is shaped so as to be connected to a screw via a socket (box wrench), and the screw tightening can be performed by aligning the tip end with a desired screw. The torque detector 11 is arranged around the main shaft 15 and is composed of a pair of coils 26 a and 26 b fixed to the impact wrench body 10. The main shaft 15 is made of a material having a magnetostrictive effect in which a pair of left and right groove rows 27a and 27b having different spiral angles are provided, and the coils 26a and 26 are opposed to the groove rows 27a and 27b.
b is arranged. And these coils 26a,
The torque acting on the main shaft 15 can be detected by 26b. Regarding the structure of the compressed air cutoff mechanism, the compressed air sent to the air motor unit 13 is supplied.
A shut-off valve 12 for shutting off is provided in the middle of an air passage 17 that connects the switching valve 19 and the air motor unit 13.

Further, the control device 30 electrically connected to the impact wrench body 10 is a portion corresponding to 120 in FIG. 1, and torque signal processing for producing a torque signal by inputting a signal emitted from the torque detecting portion 11 as an input. Part 121
A peak value processing unit 122 that extracts a peak torque value for each impact from the torque signal, a free running time processing unit 128, a function indicating the relationship between the torque-fastening force conversion coefficient and the fastening force, and the first impact. The fastening force data / memory unit 123 in which a function indicating the relationship between the obtained fastening force and the free running time included in the torque waveform at that time is recorded, the fastening force calculation unit 124, and the calculated fastening force is appropriate. And a power control unit 125 that sends an open / close control signal to the shut-off valve 12 by determining whether or not it is within the range. In addition, the above 121 to 12
Since 5 and 128 have the same configuration as that in FIG. 1, the illustration thereof is omitted.

FIG. 4 is an example of a function recorded in the fastening force data / memory section 123. As shown in FIG. 4, when an impact having a certain peak torque value is applied and the fastening force at that time is small, the amount of increase in the fastening force due to the given impact becomes large, while It can be seen that when a considerable level of fastening force is generated, even if the impact has the same peak torque value, the amount of increase in fastening force added by this is not large. The specific value differs depending on the combination of the bolt, the tightened body, and the impact wrench. Such coefficient data are prepared as a function for each combination of the impact wrench, the bolt and the object to be fastened, which are objects of use of the impact wrench. As will be described later, the fastening force calculator 124 calculates the fastening force based on the peak torque value and the function data described above.

Next, the operation of the first embodiment will be described based on the flow chart shown in FIG. When the valve operating lever 20 shown in FIG. 2 is pulled, the air motor unit 1 is supplied from the air supply unit 16 via the shut-off valve 12.
By the compressed air sent to 3, the rotary drive shaft 22 of the air motor unit 13 rotates, and the rotational force thereof is converted into a shocking rotational force in the hydraulic pressure pulse generation unit 14, transmitted to the main shaft 15, and screwed. Tightening work is performed. First, after setting the value of the target fastening force cFc in step S1 of FIG. 3,
In step S2, the impact number counter is reset <count i = 0>, and in step S3, the value of the fastening force until then is reset <F (0) = 0>. Next, in step S4, screw tightening is started. In steps S5 to S13, step S6 is processing content in the free running time processing unit 128, step S10 is processing content in the peak value processing unit 122, steps S8 and S13 are processing content in the power control unit 125, and others are It is the processing content in the fastening force calculation unit 124. First, in step S5, the count i is incremented by 1, and then in step S6, the torque signal processing unit 121
The free running time t _FR is obtained based on the signal (torque signal) from. Next, in step S7, the fastening force F (1) obtained at the first impact is calculated from t _FR based on the table of the fastening force data / memory unit 123.
However, F (1) = F (t _FR ). Figure 5 shows the fastening force data
FIG. 9 is an example diagram of a function recorded in a memory unit 123 and showing a relationship between a fastening force obtained at the first impact and a free running time included in a torque waveform at that time;
For example, it can be obtained from the tightening characteristics shown in FIG. Next, in step S8, it is determined whether or not the fastening force F (1) after the first impact is greater than or equal to the target fastening force cFc. If YES, the process proceeds to step S13 described below, and if NO, steps S9 to S9. Proceeding to the loop formed in S12 and step S8, the fastening force is calculated for the second and subsequent impacts. First, after incrementing the count i by 1 in step S9, the peak peak torque value T _P (i) of the impact is obtained from the torque signal and stored in step S10. Next, step S11
Then, the torque-fastening force conversion coefficient C _{T at} F (i-1)
_F (i) is calculated based on the table of the fastening force data / memory unit 123. However, C _TF (i) = C _TF [F (i−
1)]. Next, in step S12, to calculate the increase δF fastening force by the impact _{(i) = C T F (} i) × T P (i), a further fastening force F after the impact (i), until it Fastening force, that is, the fastening force F after the previous impact
It is calculated by adding the above increment δF (i) to (i-1). Therefore, F (i) = F (i-1) + C _TF
(i) x T _P (i). Next, returning to step S8, it is determined whether or not the fastening force F (i) after impact is not less than the target fastening force cFc, and if NO, steps S9 to S1.
The loop consisting of 2 and step S8 is repeated. on the other hand,
If YES in step S8, the flow advances to step S13, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, step S
At 14, 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 S2 to perform the next screw tightening.

FIG. 6 is a comparison diagram of the calculation accuracy of the above-described embodiment and the comparative example (the above-mentioned prior application), in which the ∘ mark indicates the characteristics of the present embodiment, and the ● mark indicates the characteristics of the comparative example (in the present embodiment). The result of simulating the data in the processing of the prior application) is shown.
This example is the result when cFc = 20 kN and M8 bolts and nuts are used to fasten a fastened body having a seat surface distance of 30 mm when seated. The dependence of the torque-engagement force conversion coefficient C _{TF on} the engagement force F (C _TF-
For the F characteristic curve), both use the same table. As is clear from the characteristics shown in FIG. 6, it can be seen that the calculation accuracy of the fastening force is significantly improved in this embodiment as compared with the conventional example. As described above, in the present embodiment, the free running time is detected as the parameter included in the first impact torque waveform, and when the fastening force is calculated,
The fastening force obtained by the first impact is calculated as a function of the above free running time, and the increase amount of the fastening force in the second and subsequent impacts is obtained as a function of the peak torque value of the impact and the fastening force in advance. It is calculated as a product of a certain torque-fastening force conversion coefficient. Therefore, the fastening force obtained at the first impact, which strongly depends on the seating state immediately before that, can be calculated using the parameter reflecting the above-mentioned seating state, so the actual fastening force must be calculated accurately. Therefore, it is possible to precisely tighten the screw up to the target fastening force.

Next, FIGS. 7 to 9 show a second embodiment of the present invention, FIG. 7 is a block diagram, and FIGS. 8 and 9 are flow charts showing arithmetic processing. In this embodiment, the number of extracted data is detected as a parameter included in the waveform of the first impact torque, and when calculating the fastening force, the fastening force obtained by the first impact is calculated as a function of the number of extracted data. It is an example configured to do so.

First, the structure will be described with reference to FIG. In FIG. 7, the impact type screw tightener main body 100 includes a motor 102, an impact torque generator 103, a main shaft 104, a torque detector 101, and a tightening socket 105, as in the first embodiment. A control device 130 is connected to the impact type screw tightener main body 100. The control device 130 includes a torque signal processing unit 121, a peak value processing unit 122, and a power control unit 125 similar to those of the first embodiment, an extracted data number processing unit 138, and a first data processing unit 138.
Of the fastening force data / memory unit 133 which is slightly different from the embodiment
And a fastening force calculation unit 134.

Next, the operation of the second embodiment will be described with reference to the flow charts shown in FIGS. In addition, in FIG. 8 and FIG. 9, indicates that parts having the same reference numerals are connected. First, in step S21 of FIG. 8, the value of the target fastening force cFc is determined, and in steps S22 and S23, sampling and
After the value of the data number N _SG and extracted determination threshold torque sT _L respectively set to reset the counter of the impact number at step S24 <count i = 0>, resets the value of the tightening force to it in step S25 Yes <F
(0) = 0>. Next, in step S26, screw tightening is started.

Next, in steps S27 to S48, steps S32 to S37 are processing contents in the extracted data number processing unit 138, steps S28 to S31, and steps S41 to S45 are processing contents in the peak value processing unit 122. Steps S39 and S48 are processing contents in the power control unit 125, and others are processing contents in the fastening force calculation unit 134. First, the count i is incremented by 1 in step S27, the counter of the number of sampling data is reset in step S28 <count j = 0>, and then the process proceeds to the loop of step S29 to step S31 to perform a predetermined sampling for the first impact. Torque data T (i, j) is sampled and stored for the number of data N _SG . That is, after incrementing the count j by 1 in step S29, the torque data T (i, j) is sampled and stored based on the torque signal in step S30.
Next, in step S31, the count j is sampled.
It is determined whether or not the number of data is equal to N _SG, and if NO, that is, if sampling is not completed, the process returns to step S29 to repeat step S31. On the other hand, in step S31, YE
When S is reached, that is, when it is determined that sampling is completed,
In step S32, the counter of the sampling data number is reset again <count j = 0>, and in step S33, the value of the extracted data number N _DS up to then is reset <N
_DS = 0>, the process proceeds to the loop from step S34 to step S37, and the number of extracted data N _DS at the first impact is calculated. That is, after the count j is incremented by 1 in step S34, the torque data T (i,
j) it is determined whether the extraction determination threshold torque sT _L or more, if NO the process proceeds to step S37, after increasing by 1 the extraction data number N _DS in step S36, if YES, the step S37 Go to. In step S37, it is determined whether or not the count j is equal to the number of sampling data N _SG. If NO, that is, if there is unprocessed torque data, the process returns to step S34 and returns to step S34.
Repeat up to 37. On the other hand, if YES in step S37, that is, if the number of extracted data N _DS is obtained, the process proceeds to step S38 in FIG. 9 (→), and the fastening force F (1) obtained at the first impact is set to the fastening force data / memory unit 133.
Calculate from N _DS based on the table in However, F
(1) = F (N _DS ). Here, FIG. 10 shows fastening force data
It is an example figure of a function which shows the relation between the fastening force obtained at the first impact and the free running time contained in the torque waveform at that time, which is recorded in the memory unit 133.
For example, it can be obtained from the tightening characteristics as shown in FIG.

Next, in step S39, it is determined whether or not the fastening force F (1) after the first impact is greater than or equal to the target fastening force cFc. If YES, the process proceeds to step S48 described later, and if NO, the step Proceeding to the loop formed from S40 to step S47 and step S39, the fastening force is calculated for the second and subsequent impacts. First,
In step S40, the count i is incremented by 1. Next, steps S41 to S44 are the same as steps S28 to S31 described above, and the torque data T (i, j) is sampled and stored. Next, in step S45, the peak of impact is detected from the torque signal.
The torque value T _P (i) is calculated and stored. Next, step S
In 46, F (i-1) Torque in - a fastening force conversion coefficient C _{T F} (i), is calculated based on the tightening force data memory unit 133 table. However, C _TF (i) = C
_TF [F (i-1)]. Next, in step S47, the amount of increase in fastening force due to impact δF (i) = C _{T F} (i) × T
Calculate _P (i), and further tightening force F after this impact
(i) is calculated by adding the increment 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). Next, step S
Returning to step 39, it is determined whether the post-impact fastening force F (i) is greater than or equal to the target fastening force cFc. If NO, the loop of steps S40 to S47 and step S39 is repeated. On the other hand, if YES in step S39, the flow advances to step S48, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, in step S49, 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 S24 in FIG. 8 (→) to perform the next screw tightening.

FIG. 11 is a comparison diagram of the calculation accuracy between the above-described embodiment and the comparative example (the above-mentioned prior application), in which the ∘ mark represents the characteristics of the present embodiment, and the ● mark represents the characteristics of the comparative example (of the present embodiment). The result of simulating the data in the processing of the prior application) is shown. This example is the result when cFc = 20 kN and M8 bolts and nuts are used to fasten a fastened body having a seat surface distance of 30 mm when seated. The dependence of the torque-engagement force conversion coefficient C _{TF on} the engagement force F (C in FIG. 4 above).
_{For TF-} F characteristic curve), both use the same table. As is clear from the characteristics of FIG. 11, it is understood that the calculation accuracy of the fastening force in the present embodiment is significantly improved as compared with the conventional example.

The above "sampling data number N"
_SG "and" extraction determination threshold torque sT _L ", in preliminary experiments carried out using the possible bolt tension measurement, it can be determined from the change in the tension of the waveform and bolt impact torque during engagement. Also, the above N _SG and sT _L
The value, screw driver, bolt, since a different value by a combination of the fastened member can be changed to N _SG and sT _L depending on the combination, i.e. capable of variably setting for each fastening site It is like this. As described above, in the present embodiment, the number of extracted data is detected as a parameter included in the waveform of the first impact torque, and the fastening force obtained by the first impact is extracted when the fastening force is calculated. It is calculated as a function of the number of data, and the increase amount of the fastening force at the second and subsequent impacts is calculated as the product of the peak torque value of the impact and the torque-fastening force conversion coefficient that is obtained in advance as a function of the fastening force. I am trying to do it. Therefore, the fastening force obtained at the first impact, which strongly depends on the seating state immediately before that, can be calculated using the parameter reflecting the above-mentioned seating state, so the actual fastening force must be calculated accurately. Therefore, it is possible to precisely tighten the screw up to the target fastening force.

Next, FIGS. 12 and 13 show a third embodiment of the present invention, FIG. 12 is a block diagram, and FIG. 13 is a flow chart showing arithmetic processing. In this embodiment, the free running time is detected as a parameter included in the waveform of the first impact torque, and the fastening force obtained by the first impact is calculated as the peak torque value of the impact when calculating the fastening force. This is an example configured to calculate as a product of a torque-engagement force conversion coefficient previously obtained as a function of the engagement force and a correction coefficient given as a function of the above free running time. First, the configuration will be described with reference to FIG. In FIG. 12, the impact type screw tightener main body 100 includes a motor 102, an impact / torque generator 103, and a spindle 1 as in the first embodiment.
04, torque detector 101 and tightening socket 105
Consists of. A control device 140 is connected to the impact type screw tightener main body 100. The control device 140 is
In addition to the torque signal processing unit 121, the peak value processing unit 122, the free running time processing unit 128, and the power control unit 125 which are the same as those in the first embodiment, a fastening force data / memory unit which is slightly different from the first embodiment. 143 and a fastening force calculation unit 144 are provided.

Next, the operation of the third embodiment will be described based on the flow chart shown in FIG. First, step S
After setting the value of the target fastening force cFc at 51, the impact number counter is reset at step S52 <count i = 0>, and the value of the fastening force up to that time is reset at step S53 <F (0 ) = 0>. Next, in step S54, screw tightening is started. Next, in steps S55 to S67, step S56 is the processing content in the free running time processing unit 128, and step S58 and step S63 are the peak value processing unit 1.
22 is the processing content, the steps S61 and S66 are the processing content in the power control unit 125, and the others are the processing content in the fastening force calculation unit 144. First, after incrementing the count i by 1 in step S55, the free running time t _FR is obtained based on the torque signal in step S56. Next, in step S57,
The correction coefficient P _C used to calculate the fastening force F (1) obtained at the first impact is calculated from t _FR based on the table of the fastening force data memory unit 143. However, P _C = P _C
(t _FR ). FIG. 14 is a function chart showing the relationship between the correction coefficient recorded in the fastening force data memory unit 143 and used in the calculation of the fastening force obtained at the first impact and the free running time included in the torque waveform at that time. It is an example diagram, and can be obtained from the tightening characteristics as shown in, for example, FIGS. 22 (a) and 22 (b).

Next, in step S58, the impact peak torque value T _P (i) is obtained from the torque signal and stored. Next, in step S59, F (0) torque at = 0 - the fastening force conversion coefficient C _{T F} (1), reads from the tightening force data memory unit 143 table. However, C _TF
(1) = C _TF [F (0)]. Next, in step S60,
Calculate the fastening force F (1) obtained at the first impact. _{However, F (1) = P C} × C TF (1) × T P (1). Next, in step S61, it is determined whether or not the fastening force F (1) after the first impact is greater than or equal to the target fastening force cFc, and YE
If S, the process proceeds to step S66 described later, and if NO, steps S62 to S65 and step S61.
Proceeding to the loop formed by, the fastening force is calculated for the second and subsequent impacts. First, after incrementing the count i by 1 in step S62, in step S63, the peak torque value T of impact is calculated from the torque signal.
_Find and store _P (i). Next, in step S64,
F (i-1) Torque in - fastening force conversion coefficient C _{T F} (i)
Is calculated based on the table of the fastening force data / memory unit 143. However, C _TF (i) = C _TF [F (i−
1)]. Next, in step S65, to calculate the increase δF fastening force by the impact _{(i) = C T F (} i) × T P (i), a further fastening force F after the impact (i), until it Fastening force, that is, the fastening force F after the previous impact
Calculation is performed by adding the increment δF (i) to (i-1). Therefore, F (i) = F (i-1) + C
_TF (i) x T _P (i). Next, returning to step S61,
It is determined whether or not the fastening force F (i) after impact is equal to or greater than the target fastening force cFc, and if NO, the loop of steps S62 to S65 and step S61 is repeated. On the other hand, if YES at step S61, the process proceeds to step S66, at which point a cut-off command is issued. This causes the compressed air valve to close. Next, in step S67, it is determined whether or not to end, and Y
If it is ES, the process ends, and if NO, step S
Return to 52 and tighten the next screw.

FIG. 15 is a comparison diagram of the calculation accuracy between the above-described embodiment and the comparative example (the above-mentioned prior application), in which the ∘ mark indicates the characteristics of the present embodiment, and the ● mark indicates the characteristics of the comparative example (in the present embodiment). The result of simulating the data in the processing of the prior application) is shown. This example is the result when cFc = 20 kN and M8 bolts and nuts are used to fasten a fastened body having a seat surface distance of 30 mm when seated. The dependence of the torque-engagement force conversion coefficient C _{TF on} the engagement force F (C in FIG. 4 above).
_{For TF-} F characteristic curve), both use the same table. As is clear from the characteristics of FIG. 15, it is understood that the calculation accuracy of the fastening force is significantly improved in this embodiment as compared with the conventional example.

As described above, in this embodiment, the free running time is detected as a parameter included in the waveform of the first impact torque, and the fastening force obtained by the first impact is calculated when the fastening force is calculated. , The peak torque value of the impact, the torque-fastening force conversion coefficient previously obtained as a function of the fastening force, and the correction coefficient given as a function of the above free running time, and the second and subsequent values are calculated. The amount of increase in fastening force at impact is calculated as the product of the peak torque value of impact and the above torque-fastening force conversion coefficient. Therefore, the fastening force obtained at the first impact, which strongly depends on the seating state immediately before that, can be calculated using the parameter reflecting the above-mentioned seating state, so the actual fastening force must be calculated accurately. Therefore, it is possible to precisely tighten the screw up to the target fastening force.

Next, FIGS. 16 to 18 show a fourth embodiment of the present invention. FIG. 16 is a block diagram, FIG. 17 and FIG.
8 is a flow chart showing the arithmetic processing. In this embodiment, the number of extracted data is detected as a parameter included in the waveform of the first impact torque, and the fastening force obtained by the first impact is calculated as the peak torque value of the impact when the fastening force is calculated. And a torque-fastening force conversion coefficient previously obtained as a function of the fastening force, and a correction coefficient given as a function of the number of extracted data described above.

First, the structure will be described with reference to FIG.
In FIG. 16, the impact type screw tightener main body 100
Is the same as in the first embodiment, the motor 102, the impact torque generator 103, the main shaft 104, and the torque detector 10.
1 and a tightening socket 105. A control device 150 is connected to the impact type screw tightener main body 100. The control device 150 includes a torque signal processing unit 121, a peak value processing unit 122, and a power control unit 125 similar to those of the first embodiment, and an extracted data number processing unit 138 similar to that of the second embodiment, The fastening force data / memory unit 153 and the fastening force calculation unit 154 are slightly different from those of the first embodiment.
It has and.

Next, the operation of the fourth embodiment will be described with reference to the flow charts shown in FIGS. In addition, in FIG. 17 and FIG. 18, indicates that parts having the same reference numerals are connected. First, the value of the target engagement force cFc In step S71 of FIG. 17, it is determined in step S72 and step S73, the value of the sampling data number N _SG and extracted determination threshold torque sT _L determined in advance by experiments, each set After that, step S74
Reset the impact counter with <count =
0>, the value of the fastening force until then is reset in step S75 <F (0) = 0>. Next, in step S76,
Start screw tightening. Next, in steps S77 to S101, steps S82 to S87 are processing contents in the extracted data number processing unit 138, steps S78 to S81, and steps S94 to S94.
97 is the processing content in the peak value processing unit 122, Steps S92 and S101 are the processing content in the power control unit 125, and the others are the processing content in the fastening force calculation unit 154. First, in step S77, the count i is incremented by 1, and in step S78, the counter for the number of sampling data is reset and then <count j =
0>, the process proceeds to a loop of steps S79 to S81, and the torque data T (i, j) is sampled and stored for the first impact by a predetermined sampling data number N _SG . That is, after incrementing the count j by 1 in step S79, the torque data T (i, j) is sampled and stored based on the torque signal in step S80. Next, in step S81, it is determined whether or not the count j is equal to the number of sampling data N _SG, and N
If O, that is, if sampling is not completed, step S79
Return to step S81 and repeat. On the other hand, if YES in step S81, that is, if it is determined that the sampling has been completed, the counter of the sampling data number is reset again in step S82 <count j = 0>, and the value of the extracted data number N _DS up to that point is set in step S83. After resetting <N _DS = 0>, step S84 to step S8
The process proceeds to the loop of 7 to obtain the number of extracted data N _DS at the first impact. That is, after incrementing the count j by 1 in step S84, the torque j is increased in step S85.
Data T (i, j) is determined whether the extraction determination threshold torque sT _L or more, the process proceeds to step S87 if NO, the
If YES, the number of extracted data N _{DS is set} to 1 in step S86.
After only increasing the value, the process proceeds to step S87. Step S
At 87, it is determined whether or not the count j is equal to the number of sampling data N _SG. If NO, that is, if there is unprocessed torque data, the process returns to step S84 to repeat step S87. On the other hand, step S87
If YES, that is, if the number of extracted data N _DS is obtained, the process proceeds to step S88 in FIG. 18 (→), and the correction coefficient P _C used for calculating the fastening force F (1) obtained at the first impact is used as the fastening force data. Calculate from N _DS based on the table of the memory unit 153. However, P _C = P
_C (N _DS ). FIG. 19 is a function showing the relationship between the correction coefficient recorded in the fastening force data memory unit 153 and used in the calculation of the fastening force obtained at the first impact, and the number of extracted data included in the torque waveform at that time. FIG.
For example, it can be obtained from the tightening characteristics shown in FIGS. 22 (a) and 22 (c).

Next, in step S89, the impact peak torque value T _P (i) is obtained from the torque signal and stored. Next, in step S90, F (0) torque at = 0 - the fastening force conversion coefficient C _{T F} (1), reads from the tightening force data memory unit 153 table. However, C _TF
(1) = C _TF [F (0)]. Next, in step S91,
Calculate the fastening force F (1) obtained at the first impact. _{However, F (1) = P C} × C TF (1) × T P (1). Next, in step S92, it is determined whether or not the fastening force F (1) obtained at the first impact is equal to or greater than the target fastening force cFc, and if YES, the process proceeds to step S101 described later, and N
If it is O, the process proceeds to the loop formed in steps S93 to S100 and step S92 to calculate the fastening force for the second and subsequent impacts. First, in step S93, the count i is incremented by 1. Next, in steps S94 to S97, the above step S7 is performed.
The torque data T is the same as that of 8 to step S81.
(i, j) is sampled and stored. Next, in step S98, the impact peak torque value T _P (i) is obtained from the torque signal and stored. Next, step S99.
Then, the torque-fastening force conversion coefficient C _{T at} F (i-1)
_F (i) is calculated based on the table of the fastening force data memory unit 153. However, C _TF (i) = C _TF [F (i−
1)]. Next, in step S100, 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 (i) after this impact is calculated as It is calculated by adding the increasing amount δF (i) to the fastening force, that is, the fastening force F (i-1) after the impact one time before. Therefore, F (i) = F (i-1) +
C _TF (i) x T _P (i). Next, returning to step S92, the fastening force F (i) after impact is the target fastening force cFc.
It is determined whether or not the above is true, and if NO, the loop consisting of steps S93 to S100 and step S92 is repeated. On the other hand, if YES in step S92, the flow advances to step S101, at which point a cut-off command is issued. This causes the compressed air valve to close.
Next, in step S102, it is determined whether or not to end the process. If YES, the process ends, and if NO, the process illustrated in FIG.
Returning to step S74 of (7), the next screw tightening is performed.

FIG. 20 is a comparison diagram of the calculation accuracy between the above-described embodiment and the comparative example (the above-mentioned prior application). The circles show the characteristics of this embodiment, and the circles show the characteristics of the comparative example (of this embodiment). The result of simulating the data in the processing of the prior application) is shown. This example is the result when cFc = 20 kN and M8 bolts and nuts are used to fasten a fastened body having a seat surface distance of 30 mm when seated. The dependence of the torque-engagement force conversion coefficient C _{TF on} the engagement force F (C in FIG. 4 above).
_{For TF-} F characteristic curve), both use the same table. As is clear from the characteristics shown in FIG. 20, it can be seen that the accuracy of the fastening force calculation is significantly improved in the present embodiment compared to the conventional example. Incidentally, "sampling data number N _SG" and "extraction determination threshold torque sT _L" Said,
Similar to the second embodiment, it is possible to variably set each fastening portion.

As described above, in this embodiment, the number of extracted data is detected as a parameter included in the waveform of the first impact torque, and the fastening force obtained by the first impact is calculated when the fastening force is calculated. , The peak torque value of the impact, the torque-fastening force conversion coefficient obtained as a function of the fastening force in advance, and the correction coefficient given as a function of the above-mentioned number of extracted data, and the second and subsequent values are calculated. The amount of increase in fastening force at impact is calculated as the product of the peak torque value of impact and the above torque-fastening force conversion coefficient. Therefore, the fastening force obtained at the first impact, which strongly depends on the seating state immediately before that, can be calculated using the parameter reflecting the above-mentioned seating state, so the actual fastening force must be calculated accurately. Therefore, it is possible to precisely tighten the screw up to the target fastening force.

[0042]

As described above, according to the first aspect of the invention, when the fastening force is calculated, the fastening force obtained by the first impact is the peak included in the waveform of the impact torque. -Calculate as a function of parameters other than the torque value, and regarding the increase of the fastening force at the second and subsequent impacts, the peak peak torque value of the impact and the torque-fastening force conversion coefficient that is previously obtained as a function of the fastening force. Since the calculation is performed as a product, in the invention described in claim 2 and claim 3, the free running time and the number of extracted data are detected as the parameters included in the waveform of the impact torque, respectively. , The fastening force obtained by the first impact as a function of the above free running time and the number of extracted data By doing so, the fastening force obtained at the first impact that strongly depends on the seating state immediately before can be calculated using the parameter reflecting the seating state described above. The effect that the fastening force can be accurately calculated and the screw fastening can be performed accurately up to the target fastening force is obtained. Further, in the invention described in claim 4, as for the fastening force obtained by the first impact, the peak torque value of the impact, the torque-fastening force conversion coefficient previously obtained as a function of the fastening force, and the impact Calculated as a product of a correction coefficient given as a function of a parameter other than the peak torque value included in the torque waveform, and regarding the increase amount of the fastening force in the second and subsequent impacts, the peak torque value of the impact and The calculation is performed as a product of the torque-engagement force conversion coefficient, and in the inventions according to claims 5 and 6, as parameters included in the waveform of the impact torque, respectively. Detects the free running time and the number of extracted data, and measures the fastening force obtained by the first impact. Since the correction coefficient used for the above is calculated as a function of the above free running time and the number of extracted data, it strongly depends on the seating state immediately before that, like the invention according to claims 1 to 3. Since the fastening force obtained at the first impact can be calculated using the parameters that reflect the seating state described above, the actual fastening force can be accurately calculated, and the target fastening force can be accurately calculated. The effect that the screw can be tightened is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view when configured as an impact wrench using compressed air as a power source.

FIG. 3 is a flowchart showing arithmetic processing in the first embodiment.

FIG. 4 is an example diagram of a function showing a relationship between a torque-fastening force conversion coefficient recorded in a fastening force data memory unit 123 and a fastening force.

FIG. 5 is a characteristic diagram showing the relationship between the free running time at the first impact and the fastening force obtained at the first impact.

FIG. 6 is a comparative characteristic diagram regarding arithmetic accuracy between the first embodiment and the comparative example (prior application).

FIG. 7 is a block diagram of a second embodiment of the present invention.

FIG. 8 is a part of a flowchart showing a calculation process in the second embodiment.

FIG. 9 is another part of the flowchart showing the arithmetic processing in the second embodiment.

FIG. 10 is a characteristic diagram showing the relationship between the number of extracted data at the first impact and the fastening force obtained at the first impact.

FIG. 11 is a comparative characteristic diagram regarding the calculation accuracy between the second embodiment and the comparative example (prior application).

FIG. 12 is a block diagram of a third embodiment of the present invention.

FIG. 13 is a flowchart showing arithmetic processing according to the third embodiment.

FIG. 14 is a characteristic diagram showing the relationship between the free running time and the correction coefficient Pc at the first impact.

FIG. 15 is a comparative characteristic diagram regarding the calculation accuracy between the third embodiment and the comparative example (prior application).

FIG. 16 is a block diagram of a fourth embodiment of the present invention.

FIG. 17 is a part of a flowchart showing a calculation process in the fourth embodiment.

FIG. 18 is another part of the flowchart showing the arithmetic processing in the fourth embodiment.

FIG. 19 is a characteristic diagram showing the relationship between the number of extracted data and the correction coefficient Pc at the first impact.

FIG. 20 is a comparative characteristic diagram regarding the calculation accuracy of the fourth example and the comparative example (prior application).

FIG. 21 is a diagram schematically showing the torque, the rotation angle of the bolt, and the change in the fastening force when the bolt is rotated by the impact type screw fastening device to tighten the screw.

FIG. 22 is a characteristic diagram showing an example of the relationship between the parameters included in the waveform of the first impact torque, that is, the peak torque value, the free running time, the number of extracted data, and the fastening force obtained at the first impact.

FIG. 23 is a schematic characteristic diagram showing the number of extracted data.

FIG. 24 is a sectional view of an example of a conventional device.

FIG. 25 is a flowchart showing arithmetic processing in the prior art of the applicant.

[Explanation of symbols]

10 ... Impact wrench body 11 ... Torque detection part 12 ... Shut off valve 13 ... Air motor part 14 ... Hydraulic pulse generation part 15 ... Main shaft 16 ... Air supply part 17 ... Air passage 18 ... Main valve 19 ... Switching Valve 20 ... Valve operating lever 21 ... Rotation switching lever 22 ... Rotation drive shaft 23 ... Vane 24 ... Liner case 25 ... Driving blade 26a, 26b ... Detection coil 27a, 27b
... Groove row 28 ... Relief valve 30 ... Control device 100 ... Impact type screw tightener main body 101 ... Torque detection unit 102 ... Motor 103 ... Impact torque generator 104 ... Spindle 105 ... Tightening socket 110 ... Control device 120 ... Control device 121 ... Torque signal processing unit 122 ... Peak value processing unit 123 ... Fastening force data / memory unit 124 ... Fastening force calculation unit 125 ... Power control unit 128 ... Free running time processing unit 130 ... Control device 133 ... Fastening force data / memory unit 134 ... Fastening force calculation unit 138 ... Extracted data number processing unit 150 ... Control device 153 ... Fastening force data / memory unit 154 ... Fastening force calculation unit

Claims (6)

[Claims] Claim: What is claimed is: 1. A drive means having a pulse component in a drive output, a joint part for a screw at one end, and a main shaft for tightening the screw when driven by the drive means, and a torque change of the main shaft is detected. Based on the impact type screw tightener main body having torque detection means, and 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 target fastening force is calculated. The power source applied to the drive means is controlled so as to be realized, and when the fastening force is calculated,
Regarding the fastening force obtained by the first impact,
Of the parameters included in the waveform of the torque pulse corresponding to the impact occurrence, it is calculated as a function of the parameters other than the peak value of the torque pulse. An impact-type screw tightening device comprising: a control unit that calculates a product of a peak value of a pulse and a torque-fastening force conversion coefficient that is previously obtained as a function of a fastening force. 2. The impact type screw tightening device according to claim 1, wherein the control unit generates each impact by the driving unit as a parameter included in a waveform of a torque pulse corresponding to the occurrence of the impact. The interval between the first torque pulse and the second torque pulse of the plurality of torque pulses to be generated, that is, the free running time is detected, and the fastening force obtained by the first impact is calculated as described above. An impact type screw tightening device characterized by being calculated as a function of free running time. 3. The impact type screw tightening device according to claim 1, wherein the control unit generates each impact by the driving unit as a parameter included in a waveform of a torque pulse corresponding to the occurrence of the impact. Number of data showing a value equal to or greater than a predetermined torque value when sampling a predetermined number of data at a fixed sampling interval from the rising edge of the first torque pulse of the plurality of torque pulses That is, the impact type screw tightening device is characterized in that the number of extracted data is detected, and the fastening force obtained by the first impact is calculated as a function of the number of extracted data. 4. A drive means having a pulse component in the drive output, a joint part with a screw at one end, for tightening the screw when driven by the drive means, and a torque change of the main shaft is detected. Using the impact type screw tightener main body having the torque detecting means and the peak value of the torque pulse obtained from the detection result of the torque detecting means, the increasing amount of the fastening force is calculated for each impact to sequentially determine the fastening force. Is calculated, the power source applied to the driving means is controlled so as to realize the target fastening force, and the fastening force obtained by the first impact at the time of calculating the fastening force is the torque The peak value of the pulse, the torque-fastening force conversion coefficient that was previously obtained as a function of the fastening force, and the parameters included in the waveform of the torque pulse corresponding to the impact occurrence. It is calculated as a product of a correction coefficient given as a function of a parameter other than the peak value of the torque pulse, and the increase amount of the fastening force in the second and subsequent impacts is calculated from the peak value of the torque pulse. An impact-type screw tightening device, comprising: a control unit that calculates the product of the torque-fastening force conversion coefficient. 5. The impact type screw tightening device according to claim 4, wherein the control means generates a torque pulse waveform corresponding to the occurrence of the impact for each impact by the drive means. When calculating the fastening force obtained by the above first impact by detecting the interval between the first generated torque pulse and the second generated torque pulse of the plurality of torque pulses, that is, the free running time The correction coefficient of is calculated as a function of the above free running time.
Impact type screw tightening device characterized by that. 6. The impact type screw tightening device according to claim 4, wherein the control means generates each torque by the driving means as a parameter included in a waveform of a torque pulse corresponding to the occurrence of the impact. Number of data showing a value equal to or greater than a predetermined torque value when sampling a predetermined number of data at a fixed sampling interval from the rising edge of the first torque pulse of the plurality of torque pulses That is, the impact-type screw tightening is characterized in that the correction coefficient for detecting the number of extracted data and calculating the fastening force obtained by the first impact is calculated as a function of the number of extracted data. apparatus.