JPH11320119A - Detecting device of chip wear volume for spot welding gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out a spot welding of a higher production efficiency by reducing time required for detection of a chip dressing and a chip wear quantity. SOLUTION: The device is provided with a chip dressing part 1 to polish a pair of chips 21a, 21b, a sensor 10 to detect a clamping position of each of the chips 21a, 21b, a memory part to memorize the clamping positions of the chips 21a, 21b while they are still in an unused condition, and a calculation part to calculate a wear of the chips 21a, 21b by comparing the clamped positions memorized by the memory part and those detected by the sensor 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the amount of wear of a tip welding gun which is capable of detecting the amount of wear while polishing the tip of the spot welding gun.

[0002]

2. Description of the Related Art A spot welding machine is generally used in the production of automobiles and the like. In this spot welding machine, a pair of chips provided in a spot welding gun presses a work to be welded, and performs spot welding by applying a current between the chips.

In the spot welding process, the spot welding gun is managed (for example, tip dressing, tip advance / retreat correction, etc.) so that constant welding conditions can be maintained at all times in order to enhance welding reliability.

[0004] For example, the tip is worn while being used for spot welding, and its tip becomes rough. For this reason, in the spot welding process, every time welding is performed a predetermined number of times, the tip is shaped and polished with a polishing device (tip dresser) so that the tip has a constant shape and area and the tip is smoothened. I am doing dress work.

In recent years, servo guns are frequently used as spot welding guns. However, since the servo gun adjusts the pressing force according to the position of the tip, the wear of the tip must be accurately grasped. No. For example, when a new chip is installed, the origin position of the chip in the reciprocating direction is determined, and how far the chip should be moved from this original position to contact the workpiece, and how much pressure should be applied from the contact position Is determined to be the specified pressure. However, after the chip is worn or the tip dressing operation is performed, the work cannot be pressurized to the initially expected pressure with the specified amount of advance and retreat. For this reason, in the spot welding process, the amount of chip wear is periodically detected, and the amount of advance and retreat is corrected in accordance with the amount of wear so that the pressing force of the work becomes a prescribed pressure.

[0006] Such detection of the chip wear amount and the accompanying correction of the advance / retreat amount are usually performed at the same time as the tip dressing operation described above. Known techniques for detecting the amount of chip wear include, for example, Japanese Patent Application Laid-Open No. 7-284957.
And Japanese Patent Application No. 10-000513.

[0007]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 7-28495
No. 7 and Japanese Patent Application No. 10-000513 each separately perform a chip dressing operation and a chip wear amount detecting operation. Therefore, a dedicated place and equipment are required for each process.

Further, as described above, the chip wear amount detection and the chip dressing are performed each time welding is performed a predetermined number of times, so that the cycle time of the spot welding process is extended by the time required for both. And thus adversely affect the productivity of spot welding.

The present invention has been made in view of the above points, and can reduce and reduce the space and equipment required for a tip dressing operation and a chip wear amount detecting operation. It is another object of the present invention to provide an apparatus for detecting the amount of chip wear of a spot welding gun which can shorten the time required for detecting the amount of chip wear and realize spot welding with higher production efficiency.

[0010]

Means for Solving the Problems To solve the above problems, the present invention is configured as follows. That is, the invention according to claim 1 is configured such that a tip dress portion for shaping and polishing the pair of tips while being sandwiched by a pair of tips provided in the spot welding gun, and the tip dress portion are integrally formed with the tip dress portion. And a wear amount detecting section for detecting the wear amount of the chip from the clamping position at the time of shaping and polishing the chip formed and polished by the section.

With this configuration, when the tip dressing operation is completed, the chip can be left as it is to detect the amount of wear, and the tip dressing operation and the detection of the amount of wear can be performed simultaneously. . Also,
Since the tip dress portion and the wear amount detecting portion are integrally formed, the space occupied by the both can be shared in the work area, and the work area can be reduced.

Further, in the invention according to claim 2, the wear amount detecting section includes a chip position detecting section for detecting a holding position of each of the pair of chips for holding the chip dressing section, A chip initial position storage unit for storing respective clamping positions for clamping the chip dress portion when not in use, a clamping position stored in the chip initial position storage unit, and a clamping position detected by the chip position detection unit And a wear amount calculation unit for calculating the wear amount of the pair of chips.

With this configuration, the wear amount of the chip can be calculated from the position where the chip is held at the time of chip dressing. After the chip dressing operation, the chip is released from the chip dresser, and the chip wear amount is detected to detect the wear amount. There is no need to reset the detector.

According to a third aspect of the present invention, at least one of the pair of chips is a movable chip that moves up and down by a servomotor, and the chip position detection unit of the movable chip determines the position of the movable chip based on the rotation amount of the servomotor. And detecting the holding position of the movable chip.

With this configuration, when the movable chip is configured to move up and down by a servomotor, it is not necessary to newly provide a position detection unit for the movable chip, and the number of parts of the position detection unit is reduced. Can be reduced.

According to a fourth aspect of the present invention, the movable tip and the fixed tip are shaped and polished while being sandwiched between a pair of a tip and a movable tip provided in a spot welding gun driven by a robot. A chip dress part, provided below the chip dress part,
While supporting the tip dress portion in a floating state, a tip dress portion floating support portion that is displaced in accordance with a force applied by the tip dress portion, a displacement detection unit that detects displacement of the tip dress portion floating support portion, An initial detection value storage unit that stores an initial detection value detected by the displacement detection unit when the movable chip and the fixed chip are unused, a driving amount of the movable chip by a robot, and detection by the displacement detection unit. A wear amount calculating unit that calculates the amount of wear of the movable chip and the fixed chip by comparing the calculated displacement amount of the tip dress portion floating support unit with the initial detection value stored in the initial detection value storage unit. It is characterized by the following.

With this configuration, the amount of wear of the movable tip and the amount of wear of the fixed tip can be calculated. In addition, it is possible to divert the drive amount of the movable tip from that used when the robot drives the welding gun, and it is not necessary to newly provide a configuration for detecting the position of the movable tip. The number of parts can be reduced.

According to a fifth aspect of the present invention, there is provided a correction means for correcting teaching data used when the tips perform spot welding based on the wear amounts of the pair of tips calculated by the wear amount calculation section. Is further provided.

With this configuration, the teaching data at the time of spot welding can be corrected in accordance with the current state of the chip, and spot welding can be performed based on more accurate teaching data.

[0020]

According to the first aspect of the present invention, when the tip dressing operation is completed, the chip can be left as it is to detect the amount of wear, and the tip dressing operation and the detection of the amount of wear can be performed simultaneously. Can be. Further, since the tip dress portion and the wear amount detecting portion are integrally formed, a space occupied by the both can be shared in the work area, and the work area can be reduced.

Therefore, the time required for the tip dressing operation and the subsequent chip polishing can be reduced, and the cycle time of spot welding can be shortened. Also,
The work area can be used effectively.

According to the second aspect of the present invention, the amount of chip wear can be calculated from the position of holding the chip during chip dressing, and after the chip dressing operation, the chip is released from the chip dresser.
There is no need to reset the chip to the wear amount detecting device for detecting the wear amount.

Therefore, the time required for the tip dressing operation and the subsequent tip polishing can be shortened, and the cycle time of spot welding can be shortened.

According to a third aspect of the present invention, when the movable chip is configured to move up and down by a servomotor, it is not necessary to newly provide a position detection section for the movable chip, and the number of parts of the position detection section is reduced. Therefore, the configuration of the chip wear amount detecting device for the spot welding gun can be simplified.

According to the fourth aspect of the invention, the amount of wear of the movable tip and the amount of wear of the fixed tip can be calculated, and the amount of wear of the tip can be detected in more detail. Therefore, if the teaching data at the time of spot welding is corrected using such data, the state of spot welding can be determined more accurately, and spot welding can be performed with high accuracy.

In addition, it is possible to divert the drive amount of the movable tip from that used when the robot drives the welding gun, so that it is not necessary to newly provide a configuration for detecting the position of the movable tip, resulting in wear. The number of parts of the quantity detection device can be reduced.

Further, according to the present invention, the teaching data at the time of spot welding can be corrected in accordance with the current state of the chip, and spot welding can be performed based on more accurate teaching data. . Therefore, the state of spot welding can be determined more accurately, and spot welding can be performed with high accuracy.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating the overall configuration of a tip wear amount detection device (hereinafter, referred to as a tip dresser) of a spot welding gun according to the present embodiment. FIG.
3 is a perspective view illustrating the chip dresser 41 illustrated in FIG. 1, and FIG. 3 is a block diagram illustrating the configuration of the control device 46.

The apparatus shown in FIG. 1 comprises a robot 42 for driving and supporting a welding gun 43 and a tip 2 of the welding gun 43.
A tip dresser 41 for performing a tip dressing operation and a wear amount detection for the tip dressers 1a and 21b;
1, a control device 46 for controlling both of the welding guns 43. In the present embodiment, the control device 46 is shared with a control device for spot welding performed by the welding gun 43.

The welding gun 43 has a tip 21b fixed to a gun arm 43a and a tip 21a that moves up and down by a servomotor 44. Servo motor 44
Is detected by the position detector 23 (FIG. 4) such as an encoder, and the amount of rotation of the servomotor 44 is converted to detect the position of the chip 21a based on a preset position. . Therefore, the position detector 23
Functions as a wear amount detection unit.

In the present embodiment, the encoder of the servomotor 44 is used as the position detection sensor 23. This position detection sensor is provided independently for inputting the position of the chip 21a to the control device 46. It may be what was done.

The chip dresser 41 of the present embodiment has both functions of chip dress and chip wear detection, and can simultaneously perform chip dress and chip wear detection. For this purpose, the tip dresser 41 floats the tip dress portion 1, the bracket 9 for fixing the tip dress portion 1, the guide 6 provided on the bracket 9, and the tip dress portion 1 as shown in FIG. It has a spring 8 supported in a state, and a displacement sensor 10 such as an encoder for detecting a vertical displacement of the tip dress portion 1. The displacement sensor 10 functions as a wear amount detecting unit.

The chip dressing section 1 includes chips 21a, 21
It has a cutter blade 2 for polishing b, a motor 3 for rotating the cutter blade 2, and a belt 5 and a pulley 4 for transmitting the rotation of the motor 3 to the cutter blade 2. In addition, the tip dressing section 1 includes upper and lower chips 2.
The cutter blade 2 is pressurized by being sandwiched by 1a and 21b and can be dressed at once. For this reason, the cutter blade 2 is provided on the upper and lower surfaces of the chip dress portion 1 as shown in FIG.

As shown in FIG.
And a storage unit 12. The arithmetic unit 15 receives a signal a representing the position of the chip 21a from the position detection sensor 23 provided on the servomotor 44 of the robot 42, and a signal c representing the displacement of the chip dressing unit 1 from the chip dresser 41. The result is fed back to the robot 42 as a signal b. Further, the storage unit 12 stores the calculation unit 1
The data necessary for the operation of No. 5 is stored in the
a, the displacement sensor 10 in a state where 21b is not worn,
The detection value of the position detection sensor 23, the position coordinates for performing the tip dressing, and the polishing conditions for the tip dressing operation are also stored here. Therefore, the calculation unit 15 functions as a wear amount calculation unit, and the storage unit 12 functions as a chip initial position storage unit or an initial detection value storage unit.

Further, as described above, the control device 46 is shared with the control device for spot welding. For this reason, the storage device 12 also stores the position coordinates and the movement order of the spot welding spots, the pressing position of the workpiece by the chip, and the like (hereinafter, collectively referred to as teaching data).

Next, the operation performed by the configuration including the above-described chip dresser 41 will be specifically described.

When the chip dressing operation of the chips 21 a and 21 b is started, the control device 46 drives the arm of the robot 12 to move the chips 21 a and 21 b to the coordinates stored in the storage unit 12. The coordinates are such that the centers of the unworn tips 21a and 21b are located at the center of the cutter blade 2 (x, y coordinates),
a and 21b are set so as to apply a predetermined pressure to the cutter blade 2 (z coordinate).

Accordingly, the chips 21a and 21b are moved to the center of the cutter blade 2 while being opened, and then the chips 21a are lowered to clamp the cutter blade 2 with a predetermined pressing force.

The pressing force between the chips 21a and 21b is detected, for example, by utilizing the fact that the feedback current from the servomotor 44 increases with the rotation torque of the servomotor. That is, the feedback current i corresponding to the predetermined pressure f is stored in the storage unit 12 in advance, and when the detected feedback current reaches the current i stored in advance, the feedback current i is set between the chips 21a and 21b. It is determined that a predetermined pressure has been applied and the servo motor 44
To stop.

Next, the motor 3 is rotated, and the chips 21a, 2a
1b is chip-dressed under predetermined conditions. After the completion of the tip dressing operation, the control device 46 fixes the chips 21a and 21b at the positions at the end of the tip dressing operation. At this time, the lower chip 21b contacts the cutter blade 2 in a state after polishing, and is at a position for displacing the chip dress portion 1 supported by the spring 8 by a predetermined amount (referred to as B). This position is a value smaller than the displacement amount A detected by the displacement sensor 10 without performing chip dressing when the chip is new. Note that the displacement amount A is stored in the storage unit 12. The calculation unit 15 compares the displacement amount B with the displacement amount A stored in the storage unit 12, and calculates the difference (A
-B) is stored in the storage unit 12 as the wear amount of the chip 21b.

Next, the control device 46 controls the position detecting sensor 23.
Detects the amount of rotation of the servomotor 44, and detects the position (C) of the chip 21a. The storage unit 12 stores a detection value (D) of the position detection sensor 23 when the chips 21a and 21b are not worn (when they are new).

The calculation unit 15 stores the detected position C and the storage unit 1
2 is compared with the position D stored. At this time, if the tips 21a and 21b are worn, the position C is located below the position D. The difference (C-D) between the position C and the position D includes both the wear amounts of the tip 21a and the tip 21b. Therefore, C-
A value CDA + B obtained by subtracting the wear amount AB of only the chip 21b detected earlier from D is stored in the storage unit 12 as the wear amount of the chip 21a.

The teaching data stored in the storage unit 12 is set so that the lengths of the chips 21a and 21b are not worn. For this reason, when the chips 21a and 21b are worn, even if the chip 21a is advanced or retracted according to the teaching data,
Since the tip is shorter than that at the time of the new article and shorter than that at the time of the previous tip dressing, the work cannot be pressurized with the predetermined pressing force. That is, the pressing force is reduced by the amount of wear.

Since this greatly affects the welding quality, the controller 46 corrects the spot welding teaching data from the wear amount of the chips 21a and 21b stored in the storage unit 12.

FIG. 5 is a flowchart for explaining a series of processing for detecting the amount of chip wear described above. When the tip dressing operation is started, first, the robot 42 comes to the original position where the operation starts (S1). Then, the welding gun 43 approaches the position coordinates for performing the tip dressing operation stored in the storage unit 12, sandwiches and presses the tip dressing unit 1 (S 2), and the polishing conditions stored in the storage unit 12. The chip dressing operation is started (for example, polishing time) (S3).

When the tip dressing operation is completed (S4),
The calculation unit 15 calculates the displacement amount detected by the displacement sensor 10 and the chip detected by the position detection sensor 23 while the welding gun 43 is fixed at the position coordinates where the tip dressing operation is performed, which is stored in the storage unit 12. The position of 21a is input (S5).

Then, of the input values, the displacement sensor 10
Is compared with the displacement stored in the storage unit 12 when the tip 21b is not worn to calculate the wear of only the tip 21b. Next, the position of the chip 21a detected by the position detection sensor 23 is compared with the displacement stored in the storage unit 12 when both chips 21a and 21b are not worn, and the amount of wear of both chips 21a and 21b is determined. The sum is calculated, and the chip 21 previously calculated from this value is calculated.
The wear amount of the chip 21a is calculated by subtracting the wear amount of only the b (S6), and the robot 42 is returned to the original position again (S6).
7). After the above processing is completed, the calculated both chips 21a,
The teaching data is corrected based on 21b (S8), and the tip dressing operation ends.

In the present embodiment described above, the step of detecting the amount of wear is conventionally performed after the step of the tip dressing operation, but the tip dressing operation and the detection of the amount of wear can be performed simultaneously. . For this reason, the time occupied by the tip dressing operation in the cycle time of spot welding can be made substantially zero, and the productivity of spot welding can be increased.

Further, as a chip wear amount detecting device,
Conventionally, it was necessary to separately provide a tip dresser and a wear amount detecting device, and a space occupied by two devices was required. On the other hand, in the configuration of the present embodiment, the tip dresser and the wear amount detection device are integrated, and the installation space of the device can be reduced.

Further, by correcting the teaching data of spot welding based on the detected amount of wear, it is possible to perform spot welding using the teaching data according to the actual state of the chip.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration to which a chip dresser according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view illustrating the chip dresser shown in FIG.

FIG. 3 is a block diagram illustrating the control device shown in FIG.

FIG. 4 is a diagram illustrating a state of a chip chiplessly dressed by the chip dresser of FIG. 2;

FIG. 5 is a flowchart illustrating a process according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tip dress part, 10 ... Displacement sensor, 12 ... Storage part, 15 ... Calculation part, 21a, 21b ... Tip 41 ... Tip dresser, 43 ... Welding gun, 44 ... Servo motor, 46 ... Control device.

Claims (5)

[Claims] 1. A chip dress portion for shaping and polishing said pair of chips while being sandwiched by a pair of chips provided in a spot welding gun; and a chip dress portion integrally formed with said chip dress portion and shaping and shaping by said chip dress portion. A wear amount detection unit for detecting the wear amount of the chip from a holding position at the time of shaping and polishing the chip. 2. A chip position detecting unit for detecting a holding position of each of the pair of chips for holding the chip dressing unit, wherein the wear amount detecting unit includes: A chip initial position storage unit for storing each of the clamping positions for clamping the dress portion, and comparing the clamping position stored in the chip initial position storage unit with the clamping position detected by the chip position detection unit, 2. A device for detecting the amount of chip wear of a spot welding gun according to claim 1, further comprising: a wear amount calculator for calculating the amount of chip wear. 3. At least one of the pair of chips is a movable chip that moves up and down by a servomotor, and a chip position detection unit of the movable chip determines a nipping position of the movable chip based on a rotation amount of the servomotor. The chip wear amount detecting device for a spot welding gun according to claim 2, wherein the amount of wear is detected. 4. A tip dressing section for shaping and polishing the movable tip and the fixed tip while being sandwiched between a pair of tips composed of a movable tip and a fixed tip provided in a spot welding gun driven by a robot; A tip dress portion floating support portion which is provided below the portion and supports the tip dress portion in a floating state, and which is displaced in accordance with a force applied by the tip dress portion; and a displacement of the tip dress portion floating support portion. A displacement detection unit for detecting, an initial detection value storage unit for storing an initial detection value detected by the displacement detection unit when the movable chip and the fixed chip are unused, and a driving amount of the movable chip by a robot. Storing the amount of displacement of the tip dress portion floating support portion detected by the displacement detection portion and the initial detection value. In contrast to the stored initial detection value, tip wear amount detecting apparatus of the spot welding gun, characterized in that it comprises a wear amount calculating unit for calculating the amount of wear of the movable tip and the fixed chip. 5. A correction means for correcting teaching data used when the tips perform spot welding based on the wear amounts of the pair of tips calculated by the wear amount calculation unit. Claim 2 or 4
2. A chip wear amount detection device for a spot welding gun according to claim 1.