JPH034356B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to one of a plurality of hands equipped with gripping claws.
The present invention relates to a working device equipped with an interchangeable hand in which one hand is selectively attached to a working head, and the gripping claws of the attached hand are opened and closed in accordance with numerical commands.

<Prior art> In a working device that transfers an article by gripping an article with a hand, when the opening and closing of the gripping claw provided on the hand is continuously controlled by numerical control, the position detection of a potentiometer, etc. It is necessary to provide a device to detect the position of the gripping claws. In particular, in devices in which the hand is replaced depending on the shape of the object to be gripped, there is a problem in that the position of the gripping claw cannot be accurately controlled unless the position of the gripping claw of the newly attached hand can be detected accurately. .

In other words, in devices that perform work by replacing multiple hands, the size of the object to be gripped by each hand is different, and the position of the gripping claws is not constant when the work is completed, so when a new hand is attached, In this case, it is impossible to accurately control the position of the gripping claws of a newly attached hand unless the position of the gripping claws of the newly attached hand is accurately recognized when the hand is replaced.

In order to accurately recognize the position of the gripping claws of each hand, each of the multiple hands must be equipped with a position detector such as a potentiometer to detect the position of the gripping claws. It is possible to supply the output of the potentiometer to the work head side, but if you do this,
Not only does each hand require a position detector such as a potentiometer, but also a connection device for transmitting signals between the hand and the work head, making the hand complex and large. There was a problem.

<Purpose of the Invention> Therefore, the present invention has been developed to ensure that, after hand replacement, the gripping claws of the newly attached hand are always located at the reference origin, so that the gripping claws of the newly attached hand can be positioned at the reference origin without installing a position detector such as a potentiometer on each hand. The purpose of this is to enable accurate control of the position of the gripping claws after replacement.

<Configuration of the Invention> FIG. 1 is an overall configuration diagram for clearly explaining the present invention. The gripping claw feeding mechanism in the hand is configured such as a feed screw mechanism so that the position of the gripping claws 12 does not change even after the hand 11 is removed from the work head 10.
a drive shaft 41 that is rotated by the drive shaft 6 and engaged with the claw feeding mechanism on the hand 11 side when the hand 11 is connected;
A position detecting means 43 connected to the drive shaft 41 and detecting the absolute position of the gripping claws 12 is provided. Further, in the control device 46, an origin detection means 63b is provided which detects that the gripping claw 12 is located at the reference origin based on the output of the position detection means 43, for example, and an origin return means 63a is used to detect the position of the gripping claw 12 at the reference origin before changing the hand. Drive means 36 to return the claw 12 to the reference origin
When this operation is completed, the hand exchange control means 64 operates the hand exchange device 24 to perform a hand exchange process in which the used hand 11 is removed from the work head 10 and a new hand 11 is attached to the work head 10.

As a result, when the used hand 11 is used again, it is always attached to the work head 10 with the gripping claw 12 located at the reference origin.
Even without providing a potentiometer in the hand 11, the initial position of the gripping claw 12 after hand replacement can be accurately recognized and the claw position can be controlled.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. In FIG. 2, reference numeral 10 denotes a work head to which a hand 11 equipped with a gripping claw 12 can be selectively mounted. It is guided and supported so that it can move up and down, and is moved by a servo motor 19 via a feed screw 18. Further, the cross feed table 17 serves as a passageway for the accumulation rate conveyor 20 and the conveyance cart C provided on the side of the accumulation rate conveyor 20.
The work head 10 is movably guided on a cross beam 21 disposed across the CP, and is guided by a servo motor 22 attached to the end of the cross beam 21 to move the work head 10 onto the accumulation conveyor 20 and the passage CP. It can be positioned above the transport vehicle C. Also, in Figure 2, the cross beam 2
A hand storage magazine 23 for storing a plurality of hands 11 and a hand exchange device 24 including an exchange arm 24a are provided at the left end of the hand storage magazine 23. The hand 11 inside the work head 10 can be replaced with the hand 11 on the work head 10.

As shown in FIG. 3, the hand 11 has a shank portion 11a that fits into a holding hole 10a formed at the lower end of the work head 10, and a shank portion 11a that is integrally formed at the tip of the shank portion 11a. Claw guide part 11
A screw shaft 25 having male threads in opposite directions at both ends is supported at the center of the shaft 25, and the shank portion 1
A pair of gripping claws 12 are screwed into threaded portions at both ends of the threaded shaft 25, which extend in a direction perpendicular to the axis of the threaded shaft 25. On the other hand, an input shaft 27 having an engagement piece 26 at the upper end is supported on the axis of the shank portion 11a, and this input shaft 27 and the screw shaft 25 are connected to a pair of bevel gears 28.
a, 28b. Further, as shown in FIG. 4, on the outer periphery of the input shaft 27,
A stopper ring 30 is loosely fitted so as to be movable in the radial direction, and engagement teeth 30a that engage with tooth grooves 27a carved on the outer circumference of the input shaft 27 are formed on the inner circumference of the stopper ring 30. The tip of a pressing pin 32 supported by the shank portion 11a and pressed radially inward by the disc spring 31 is engaged with the outer circumferential surface of the stopper ring 30 at a position corresponding to the position where the engaging teeth 30a are formed. shank part 1
An inner end portion of an operating shaft 33, which is supported by the shank portion 11a and whose outer portion slightly protrudes from the outer peripheral surface of the shank portion 11a, is disposed on the outer circumferential surface at a position opposite to the formation position of the engagement teeth 30a across the axis of the shaft 1a. engaged.

Therefore, when the hand 11 is attached to the work head 10 and the operating shaft 33 engages with the holding hole 10a of the work head 10 and moves inward, the engagement teeth 30a of the stopper ring 30 and the teeth of the input shaft 27 When the engagement with the groove 27a is disengaged, the input shaft 27 can rotate, the hand 11 is disengaged from the work head 10, and the engagement between the operating shaft 33 and the holding hole 10a is released, the disc spring 31 The stopper ring 30 is biased due to the repulsive force of
The rotation of the input shaft 27 is restrained.

On the other hand, a notch mechanism 35 for maintaining the attached state of the hand 11 is provided in the lower cylindrical portion of the work head 10, and a drive mechanism 36 for rotating the engagement piece 26 of the hand 11 is provided in the upper rectangular portion. ing.
This drive mechanism 36 is rotatably mounted on an extension of the axis of the holding hole 10a, and the worm wheel 4 is rotated by a servo motor 38 mounted on the outer wall of the work head 10 via a worm 37.
0 and a drive shaft 41 that extends vertically through the axial center of the worm wheel 40 and is allowed to move only in the vertical direction with respect to the worm wheel 40 through spline engagement. A downward pressing force is applied to this drive shaft 41 by a spring 42, and when the hand 11 is attached to the work head 10, the engagement teeth formed at the lower end of the drive shaft 41 engage with the engagement piece 26. engage the teeth.

Further, a drive shaft 41 is provided at the upper end of the work head 10.
A position detector 43 is provided to detect the amount of rotation. This position detector 43 is an absolute type position detector composed of a potentiometer or the like, and detects the absolute position of the gripping claw 12 of the hand 11 attached to the work head 10 and responds accordingly to the position. Outputs the analog signal. That is, assuming that the state in which the gripping claws 12 are moved to the innermost position is the reference origin of the gripping claws 12, the output of the position detector 43 is initially set to be zero at this reference origin.

Next, to explain the configuration of the control circuit, the central processing unit 50 in the numerical control device 46 is configured by a microprocessor, and this central processing unit 50 includes a memory 51, a data input device 52, and an interface 53a. , 53b are connected to the interface 53a, and the servo motors 19, 22,
The drive unit DUZ drives each of the 38
DUX and DUU are connected and interface 53b
A position detector 43 is connected to. Note that an AD converter for converting the output of the position detector 43 into a digital signal is built into the interface 53b.

The memory 51 is provided with a numerical control data area NCDA that stores numerical control programs for performing various assembly operations, and stores a plurality of sets of numerical control programs corresponding to the types of articles to be worked on. As shown in FIGS. 5a and 5b, each of the plurality of numerical control programs has a hand exchange command H code programmed in the first block to attach the hand 11 suitable for the workpiece to the work head 10. When this H code is read out, the currently installed handle 11 is returned to the hand storage magazine 23, and the hand 1 to be used next is returned.
1 to the working head 10.

Now, the work of transferring the article Wa from the accumulation rate conveyor 20 to the conveyance cart C has been completed, and the work of transferring the article Wb of a different shape from the accumulation rate conveyor 20 to the conveyance truck C is now performed. Then, the product number of the article Wb and the start command START are given to the central processing unit 50 from the main computer (not shown). Then, the central processing unit 50 executes the program shown in FIG. 6. First, in step 60, a numerical control program to be executed is selected based on the article number, and in step 61, one block of the program is read out.
If the read program is an H code that commands hand exchange, step 62
The process then proceeds to step 63 to perform hand exchange processing, and if the read program is a movement command, the process proceeds from step 65 to step 66 to perform pulse distribution processing.

Since the first block of the numerical control program for transferring each article is programmed with an H code that commands the exchange of the hand 11, this is first read out in step 61, and then the process moves to step 63 to exchange the hand. Execute the process.

This hand exchange process consists of an operation of returning the gripping claws 12 to the reference origin in step 63, and a hand exchange operation in step 64. In step 63, as shown in FIG. It is determined in step 63b whether the output is zero or not, and if it is not zero, step 63c is performed.
By repeating this process, the gripping claw 12 of the used hand 11 is finally located at the reference origin, and the output of the position detector 43 becomes zero. Return to standard position.

Then, in the subsequent step 64, after positioning the cross-travel table 17 at the replacement position shown by the two-dot chain line in FIG. is performed in cooperation with the exchange control circuit 47.

As a result, the hand 11 for the article Wa is returned to the hand storage magazine 23, and the hand 11 for the article Wb is newly attached to the work head 10, but the hand 11 for the article Wb is operated in the same manner as described above. Since the gripping claws 12 have been returned to the reference origin at the time of returning to the hand storage magazine 23, the work head 10 is moved with the grasping claws 12 located at the reference origin.
is attached to the position of the gripping claw 12 and the position detector 43
The relationship with the output of is consistent. Therefore, following hand exchange, the gripping claws 12 can be opened and closed accurately based on the movement command data that is programmed. That is, when distributing pulses to the U axis in step 67, the central processing unit 50 calculates the deviation between the absolute movement command value commanded by the numerical control program and the output of the position detector 43, and calculates the deviation between the absolute movement command value commanded by the numerical control program and the output of the position detector 43. The number of pulses depending on the deviation is U
However, as mentioned above, since the relationship between the output of the position detector 43 and the position of the gripping claw 12 is correctly aligned during hand exchange, the gripping claw 12
will be accurately moved to the commanded position.

In addition, the transfer work of goods Wb has been completed and the goods Wb have been transferred again.
When carrying out the work of transferring Wa, the process of exchanging the hand 11 for article Wa and the hand 11 for article Wb is performed based on the H code programmed at the beginning of the numerical control program for article Wa. This is carried out in the same manner as in the above case, but the hand 11 of the article Wa is returned to the hand storage magazine 23 with the gripping claw 12 located at the reference origin due to the previous hand exchange operation described above, and the work is carried out again in this state. Since it is attached to the head 10, a new work head 10 is installed.
The relationship between the position of the gripping claw 12 and the output of the position detector 43 is also accurately matched with respect to the hand 11 for the article Wa attached to the hand 11, and even after hand replacement, the gripping claw 12
This means that the position can be precisely controlled.

In the above embodiment, the position detector 43 was of an absolute type, but the position detector 43 is constituted by a pulse generator, etc., and the output of the pulse generator is counted by a counter, so that the gripping claw can be adjusted. 12
The present invention can also be applied to detecting the position of.
In this case, when the count value of the counter reaches a specific value, for example, zero, it can be detected that the gripping claws 12 have returned to the reference origin.

<Effects> As described above, in the present invention, the origin detection means for detecting that the gripping claws are located at the reference origin and the origin detection means for returning the gripping claws to the reference origin are provided, and the Since the gripping claw of the used hand is returned to the reference origin and then the hand is replaced, the gripping claw of the hand newly attached to the work head is always located at the reference origin, and each of the multiple hands Even without providing a position detector such as a potentiometer, accurate control can be performed by controlling the position of the gripping claws with reference to the reference origin after hand replacement.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram for clearly demonstrating the present invention.
2 to 7 show embodiments of the present invention,
FIG. 2 is a diagram showing the overall configuration of the actuating device together with a block diagram showing the control circuit, FIG. 3 is a vertical cross-sectional view showing the configuration of the work head 10 and hand 11 in FIG. 5a and 5b are diagrams showing the numerical control program stored in the numerical control data area NCDA in FIG. 2, and FIG. 6 is an operation of the central processing unit 50 in FIG. 2. FIG. 7 is a flowchart showing details of step 63 in FIG. 10... Working head, 11... Hand, 12...
... Gripping claw, 24 ... Hand exchange device, 25 ... Screw shaft, 27 ... Input shaft, 28a, 28b ... Bevel gear, 36 ... Drive mechanism, 41 ... Drive shaft, 43
...Position detector, 50...Central processing unit.

Claims (1)

[Claims] 1.Equipped with an exchangeable hand in which a specific one of a plurality of hands equipped with gripping claws is selectively attached to a work head, and the gripping claws of the attached hand are opened and closed in accordance with numerical commands. In the work device, a drive shaft that engages with a claw moving mechanism on the hand side when the hand is attached, and a drive means that displaces the drive shaft to move the gripping claw are provided on the work head side, and An origin detecting means for detecting that a gripping claw of a hand attached to a work head is located at a reference origin, an origin return means for moving the grasping claw to the reference origin before replacing the hand, and the origin return means 1. A working device equipped with an exchangeable hand, characterized in that it is equipped with a hand exchange control means for exchanging the hand after the gripping claw is returned to the reference origin.