JPH06344151A - Electric welding equipment - Google Patents

Abstract

(57) [Summary] [Purpose] To ensure that resistance welding is always performed with an appropriate clamping load and the cycle time is shortened. [Structure] After moving the workpiece to the welding position by the material handling robot, at the same time, the upper electrode of the pinching robot is moved to the initial welding position (S1), and the nut is fed by the nut feeder (S2), and then the upper electrode of the pinching robot. Is further lowered to pressurize the work with the lower electrode, and the servomotor of the pinching robot is fed back so that the pinching load L detected by the load detection sensor such as the load cell becomes a preset load Lo. Control (S3). Then, at the time of pressurization in S3, when Lo ≦ L, a welding current is passed between the pair of electrodes (S4, S5).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding device for sandwiching a work between a pair of electrodes to perform resistance welding, and more particularly to an electric welding device for relatively approaching a pair of electrodes using an electric motor as a drive source. It is a thing.

[0002]

[Prior art]

(A) A clamping robot that clamps a work by bringing a pair of electrodes relatively close to each other, and (b) the clamping robot and the work are relative to each other so that a welding portion of the workpiece is located between the pair of electrodes. A welding device equipped with a mobile robot for moving and (c) a welding power source for resistance welding the work by passing a welding current between the pair of electrodes is widely used in automobile parts manufacturing lines and assembly lines. It is being appreciated. An air cylinder is generally used as a drive source for the pinching robot, and the pinching load between a pair of electrodes has been controlled by the air pressure of the air cylinder. In recent years, an electric motor has been used as a drive source. A pinching robot has been proposed. Japanese Utility Model Laid-Open No. 3-106279 and JP-A-61-253189.
The device described in the publication is an example thereof, and detects a clamping load from the torque of the electric motor, and when the torque reaches a predetermined value, a welding current is supplied from a welding power source, or the torque is The motor torque is controlled so as to have a predetermined value.

[0003]

However, when the clamping load is detected from the torque of the electric motor as described above, the sliding resistance and rolling resistance of the conversion mechanism for converting the rotational output of the electric motor into the clamping load. However, due to such changes over time, high accuracy could not always be obtained, and there was a risk of defective welding due to excessive and insufficient clamping pressure. In addition, conventional welding equipment
The mobile robot positions the welding part of the work between the pair of electrodes while holding the pair of electrodes at the most distant original position, and then the pair of electrodes is relatively approached by the pinching robot to pinch the work. Because it was like
It takes time to clamp the work between a pair of electrodes,
There was a problem that the cycle time became long.

The present invention has been made in view of the above circumstances. A first object of the present invention is to always perform resistance welding with an appropriate clamping load, and a second object thereof is a cycle time. Is to shorten.

[0005]

In order to achieve the above object, the first aspect of the present invention is, as shown in the claim correspondence diagram of FIG. 1, (a) using an electric motor as a drive source and a pair of electrodes relative to each other. And a clamping robot that clamps the work by closely approaching each other,
(B) a mobile robot that relatively moves the clamping robot and the work so that a welding part of the work is located between the pair of electrodes using an electric motor as a drive source
(C) An electric welding device including a welding power source for resistance welding the work by passing a welding current between the pair of electrodes, wherein (d) the mobile robot and the pinching robot are simultaneously operated. And (e) a simultaneous movement control means for locating the welding part of the work between the pair of electrodes and for relatively bringing the pair of electrodes closer to each other; And (f) the pair of electrodes are brought close to each other to clamp the work, and the clamping load detected by the load detection sensor becomes a predetermined set load. As described above, (c) clamping control means for feedback-controlling the electric motor of the clamping robot, and (g) the load detection sensor for controlling the operation of the clamping robot by the clamping control means. When clamping pressure load detected reaches the welding start load predetermined and having a energization control means for energizing the welding current between the pair of electrodes from the welding power source.

[0006]

In such an electric welding apparatus, first,
The mobile robot and the pinching robot are simultaneously actuated by the simultaneous movement control means, the welding part of the work is positioned between the pair of electrodes, and the pair of electrodes are relatively brought close to each other. These operations are preset by teaching or the like according to the shape of the work so as not to interfere with each other, and the pair of electrodes are finally approached as close as possible while being separated so as not to interfere with the work or the like. Just do it. Further, both robots do not always have to operate simultaneously at the same time, and while one robot is operating, the other robot may temporarily operate simultaneously.

Thereafter, the clamping pressure control means further clamps the work by bringing the pair of electrodes closer to each other, and clamps the workpiece so that the clamping load detected by the load detection sensor becomes a predetermined set load. The electric motor of the robot is feedback-controlled. The approaching operation of the pair of electrodes by the pinching control means may be performed continuously with the approaching operation of the pair of electrodes by the simultaneous movement control means, but a workpiece such as a nut is supplied to supply the workpiece. When welding is to be performed, it is possible to temporarily stop the welding at a position that does not hinder the supply thereof and then start the operation by the pinching control means.

During operation control of the pinching robot by the pinching control means, the energization control means determines whether or not the pinching load has reached a predetermined welding start load, and when the welding start load is reached. A welding current is passed from the welding power source between the pair of electrodes to start resistance welding. The welding start load may have the same value as the set load, but a value smaller than the set load may be set in consideration of control error and the like.

[0009]

As described above, according to the electric welding apparatus of the first aspect of the present invention, when the moving portion of the work is relatively positioned between the pair of electrodes by the mobile robot, the pair of pinching robots simultaneously perform the pairing. Since the electrodes are made to approach each other, the amount of electrode movement when the work is pinched and then welded is reduced, and the cycle time is shortened accordingly. Further, since the load detection sensor provided in the pinching robot detects the pinching load, sliding resistance and rolling resistance of the conversion mechanism for converting the rotation output of the electric motor into the pinching load,
The pinching load is always detected with high accuracy regardless of such changes over time, and the operation of the pinching robot is controlled based on the pinching load, and resistance welding is started. Welding defects due to shortage are prevented.

[0010]

A second aspect of the present invention is directed to (a) a pinching robot that pinches a workpiece by relatively approaching a pair of electrodes using an electric motor as a drive source;
(B) An electric welding device comprising: a welding power source for resistance welding the work by passing a welding current between the pair of electrodes; (c) the pair of electrodes provided in the pinching robot; A load detection sensor that detects the clamping load between the electrodes,
(D) The pair of electrodes are brought close to each other to clamp the work, and an electric motor of the clamping robot is fed back so that the clamping load detected by the load detection sensor becomes a preset load. When the clamping load detected by the load detection sensor reaches a predetermined welding start load during operation control of the clamping robot by the clamping control means for controlling (e) the clamping control means, the welding is performed. An energization control unit that energizes a welding current from a power source between the pair of electrodes is provided.

[0011]

In such an electric welding apparatus, the clamping pressure control means causes the pair of electrodes to approach each other to clamp the workpiece, and the clamping load detected by the load detection sensor becomes a predetermined set load. In addition, the electric motor of the pinching robot is feedback-controlled. Then, during operation control of the pinching robot by the pinching control means, the energization control means determines whether or not the pinching load has reached a predetermined welding start load, and when the welding start load is reached, the welding power source A welding current is passed between the pair of electrodes to start resistance welding. The welding start load may have the same value as the set load, but a value smaller than the set load may be set in consideration of control error and the like.

[0012]

According to the electric welding apparatus of the second aspect of the invention, the load detection sensor provided in the pinching robot detects the pinching load. The pinching load is always detected with high accuracy regardless of the sliding resistance and rolling resistance of the conversion mechanism that converts the rotational output to the pinching load, and changes over time such as these. Since the operation is controlled and the resistance welding is started, welding failure due to excess or deficiency of the clamping load is prevented.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a perspective view showing a main part of an electric welding apparatus according to an embodiment of the present invention, which includes a pinching robot 10 and the like. The pinching robot 10 includes a lower electrode 16 integrally arranged on the main body frame 14 via a lower bracket 12 and a pressure unit 20 attached to the main body frame 14 via an upper bracket 18. . The pressure unit 20 converts the rotational output of the electric servomotor 24 into a linear motion by a conversion mechanism 22 having a ball screw or the like, and drives the output shaft 26 up and down. The output shaft 26 detects a load such as a load cell. The upper electrode 30 is attached via the sensor 28. The lower electrode 16 and the upper electrode 30 are connected to a transformer 36 as a welding power source via cables 32 and 34, respectively, and a welding current is supplied thereto.

In the vicinity of the pinching robot 10, a material handling robot 38 is arranged as a mobile robot. This material handling robot 38
A multi-axis robot including a plurality of electric servomotors 40 (see FIG. 3) is used to hold and move a work 46 by a material handling jig 44 attached to a robot hand 42 at the tip. Through holes 48 are formed in the workpiece 46 at a plurality of positions where the nuts are to be welded, and the material handling robot 38 is arranged so that the welding portions having the through holes 48 are located on the lower electrode 16. Sequentially moved by. A pilot pin 50 is arranged in the central portion of the lower electrode 16 so as to project upward, and the material handling robot 38 moves while moving the workpiece 46 up and down so that the pilot pin 50 can be inserted into the through hole 48. Then, the respective welding parts are sequentially placed on the lower electrode 16. The material handling jig 44 holds the work 46 in a state where the work 46 can be relatively moved in the vertical direction.
6 is placed in a state of surely contacting the lower electrode 16.

Further, a nut feeder 52 is attached to the main body frame 14 of the pinching robot 10 so that the nut to be welded to the work 46 is supplied onto the pilot pin 50 through the inside of the guide tube 54. ing.

The operation of the electric welding apparatus is controlled by the controller 56 shown in FIG. The controller 56 is configured to include a microcomputer having a CPU, a RAM, a ROM, etc., performs signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM, and drives signals SDP, SDM, etc. The nut supply command signal SA and the welding command signal SW are output. The drive signal SDP is output to the servo amplifier 58 that supplies drive power to the servo motor 24, and controls the drive power, for example, the motor current, to control the rotation speed and torque of the servo motor 24. The servo motor 24 is provided with an encoder 60, and its rotational position,
That is, the electrode position signal SXP indicating the electrode position XP of the upper electrode 30 is supplied to the controller 56 via the servo amplifier 58. The drive signal SDM is output to each servo amplifier 62 that supplies drive power to each of the plurality of servo motors 40 of the material handling robot 38,
The material handling robot 38 is controlled so that the material handling jig 44 can be moved along a preset path by controlling each driving power. Each servo motor 40 is provided with an encoder 64, and a rotation position of each servo motor 40, that is, an axis position signal SXM representing the axis position XM of each axis of the material handling robot 38, is sent to the controller 56 via the servo amplifier 62. Supplied. The nut supply command signal SA is output to the controller of the nut feeder 52, and one nut is supplied from the nut feeder 52. Whether or not the nut is supplied is detected by a sensor such as a limit switch, and when the nut supply is completed, a supply completion signal SEA is supplied from the nut feeder 52 to the controller 56. The welding command signal SW is output to the timer contactor 66 connected to the transformer 36, and the welding current Iw is applied between the upper electrode 30 and the lower electrode 16 from the transformer 36 for the welding time Tw. The welding time Tw and the welding current Iw are preset in the timer contactor 66 according to the welding conditions.
When the welding time Tw elapses and the energization ends, the welding completion signal SEW is sent from the timer contactor 66 to the controller 56.
Is supplied to. A load signal SL representing the load detected by the load detection sensor 28, that is, the clamping load L between the upper electrode 30 and the lower electrode 14, is also supplied to the controller 56 via an amplifier or an A / D converter. To be done.

Such an electric welding apparatus is shown in FIG.
Weld according to the flow chart. At the beginning of welding, the material handling jig 44 of the material handling robot 38 is positioned at the predetermined delivery position, and the upper electrode 30 of the pressure unit 20 is positioned at the rising end. In step S1, By outputting the drive signals SDP and SDM respectively in accordance with the movement path data stored in advance in the RAM or the like, the material handling robot 38 moves the work 46 received at the delivery position to place the first welding site on the lower electrode 16. The upper electrode 30 of the pressure unit 20 is lowered to a predetermined welding initial position while being operated to be placed. These movements are performed in parallel and at the same time, and the respective movement route data are preset by teaching or the like so as not to interfere with each other. Further, the initial welding position of the upper electrode 30 is set to a position as low as possible so that the descending amount at the time of pressure welding is reduced, and at a position where the nut supply by the nut feeder 52 is not hindered.

In step S2, a nut supply command signal SA is output to the nut feeder 52, so that the nut is supplied onto the pilot pin 50. Nut feeder 5
When the supply completion signal SEA is supplied from 2, the step S3 is subsequently executed, the drive signal SDP is output to lower the upper electrode 30, and the work 46 and the nut are clamped between the lower electrode 16 and The torque of the servo motor 24 is feedback-controlled so that the clamping load L represented by the load signal SL becomes a preset load Lo. In step S4, it is determined whether or not the clamping pressure L has reached the welding start load, which is the set load Lo in this embodiment in accordance with the execution of step S3, and when it reaches the set load Lo, the welding command is issued in step S5. The signal SW is output to the timer contactor 66. As a result, the welding current Iw is passed between the upper electrode 30 and the lower electrode 16 from the transformer 36 only for the predetermined welding time Tw, and the nut is resistance welded to the first welding portion of the work 46. Even during the welding in step S5, the servo motor 24 is feedback-controlled so that the clamping load L becomes the set load Lo. The set load Lo may be a constant value, but it may be changed with the passage of time or the electrode position XP due to melting during welding.
It can also be changed according to the change of. The welding current Iw can also be changed in accordance with the passage of time or changes in the electrode position XP. When the welding time Tw elapses and the welding completion signal SEW is supplied from the timer contactor 66, step S6 is executed, the servo motor 24 is reversely driven by the drive signal SDP, and the upper electrode 30 is welded in step S1. Raise to the initial position. FIG. 5 shows the electrode position XP, the clamping load L, and the welding currents ON and O in steps S3 to S6.
In the time chart showing the change of FF, time t ₁ is at the start of step S3, time t ₂ is at the start of step S5, time t ₃ is at the start of step S6, and time t ₄ is at the step S.
It is the end of 6.

In the next step S7, it is judged whether the welding is good or not based on the clamping load L and the electrode position XP when the welding current is applied in step S5. If the welding is OK, then step S9 is executed. In the case of welding NG, step S8 is executed, the subsequent operation is stopped, and the abnormality is notified by an abnormal lamp or an abnormal buzzer. This welding determination is performed, for example, according to the flowchart of FIG. 6, and it is determined in step R1 whether or not the actual clamping pressure L during welding in step S5 is within a predetermined load range (Lo ± α). , Step R2, Step S5
Change amount ΔXP of the electrode position XP before and after welding, that is, whether the amount of penetration accompanying welding is equal to or greater than a predetermined amount of penetration β1 and equal to or less than β2, and if any determination is YES, step R3 In step R4, if the welding is OK, the welding OK is determined. If NO in either one, the welding NG is determined. It is also possible to make the welding determination in consideration of other conditions that influence welding, such as whether the welding current Iw is within a predetermined range.

The welding determination shown in FIG. 6 may be performed during the welding in step S5, and the welding current Iw may be stopped when the welding becomes NG. In addition, as shown in FIG. 7, whether the electrode position XPa before the start of welding in step S5, that is, when the clamping pressure L reaches the set load Lo is within the range of the predetermined position XP1 or more and XP2 or less. It is judged whether or not it is out of the range, and the operation after step S5 is stopped, or as shown in FIG. 8, it is judged whether or not the electrodes 16 and 30 are worn based on the electrode position XPa. You can also To judge the wear of the electrodes 16 and 30, the electrode position XPa at the time of the first welding after electrode replacement is stored as the reference position XPo, and the electrode position XPa at the time of subsequent welding and the reference position XPo are compared. X
It can be determined whether Pa-XPo is less than or equal to a predetermined determination value γ.

Returning to FIG. 4, in step S9, which is executed when the welding determination in step S7 is OK, it is determined whether or not all the weldings for one work 46 have been completed, for example, a counter is used to count the number of weldings. If the welding portion remains, the steps S1 and thereafter are repeated. In step S1, the drive signals SDP and SDM are output according to the movement path data for the next welding site,
The work 46 is moved and the upper electrode 30 is moved up and down so as not to interfere with the work 46. Work 4
When the movement of 6 does not interfere with the upper electrode 30 held at the welding initial position at the time of the previous welding in step S6, the movement of the upper electrode 30 is unnecessary. Further, the initial welding position of the upper electrode 30 may be set to a different position for each welding site depending on the shape of the work 46, but may be set to a fixed position. In addition, the step S6
Alternatively, it is possible to immediately return to step S1 and move the work 46 to the next welding position while moving the upper electrode 30 up and down.

In this way, the work 46 is moved in step S1 and the upper electrode 30 is moved up and down as needed, and the steps S2 and subsequent steps are performed, whereby nuts are sequentially welded to a plurality of welding portions of the work 46. Then, all the welding is completed and the determination in step S9 is YES.
Then, in step S10, the workpiece 46 is moved to the delivery position by the material handling robot 38, and the upper electrode 30 is moved to the rising end. The movement at this time is also performed at the same time. As a result, the welding work for one work 46 is completed.

Here, in the electric welding apparatus of the present embodiment, since the work piece 46 is moved by the material handling robot 38 in step S1, the upper electrode 30 is moved to the initial welding position in parallel, so that the upper electrode is moved in step S3. The amount of movement when the electrode 30 is lowered and pressed is reduced, and the cycle time is shortened accordingly. Further, since the load detection sensor 28 provided in the pinching robot 10 detects the pinching load L, the ball screw or the like is compared with the case where the pinching load is obtained from the torque of the servo motor 24. The pinching load L is always detected with high accuracy regardless of the sliding resistance and rolling resistance of the conversion mechanism 22 that it has, and their changes over time.
The servomotor 24 is feedback-controlled so that the clamping load L becomes the set load Lo, and resistance welding is started at the time when Lo ≤L. Therefore, the clamping load L during welding is excessive or insufficient. Welding failure is prevented.

In the present embodiment, of the series of signal processing by the controller 56, the part that executes step S1 corresponds to the simultaneous movement control means, the part that executes step S3 corresponds to the pinching control means, and step S4. The part that executes S5 and S5 corresponds to the energization control means.

Next, another embodiment of the present invention will be described. 9 and 10 are a partially cutaway front view and a right side view showing a spot welding gun 70 as a pinching robot. This spot welding gun 70 has a base plate 7
A mobile robot 122 such as an articulated robot having a plurality of electric servomotors 120 (see FIG. 11).
The spot welding is carried out by sequentially moving the workpiece to a plurality of welding parts which are attached to the workpiece and are fixedly positioned such as an automobile body. An upper arm 78 and a lower arm 80 are attached to the base plate 72 via a support frame 74 so as to be rotatable around a support shaft 76, and a body 82 is integrally fixed to the upper arm 78. . A ball nut 86 is disposed in the main body 82 via a bearing 84 so as to be immovable in the axial direction and rotatable about the axis, and the ball nut 86 is screwed into a threaded portion 92 a of a shaft 92. At the same time, it is rotated by an electric servomotor 90 via a timing belt 88. The shaft 92 is provided with a spline portion 92b on the side opposite to the screw portion 92a, and the spline portion 92b is movable in the axial direction and rotatable about the axis with respect to a ball spline 94 which is non-rotatably arranged in the main body 82. When the ball nut 86 is rotatably driven by the servo motor 90, the shaft 92 is axially moved. The upper arm 78 is fixed to the support frame 74 at a predetermined position around the support shaft 76, and the servo motor 90 is integrally fixed to the main body 82.

A knuckle 96 is attached to an end portion of the shaft 92 on the spline portion 92b side, and is connected to the lower arm 80 via a link 98. By moving the shaft 92 in the axial direction, The lower arm 80 is rotated around the support shaft 76. A load detection sensor 10 such as a load cell is provided at the tip of the lower arm 80.
The lower electrode 102 is attached via 0, and the lower electrode 1 is attached to the tip of the upper arm 78.
02, the upper electrode 104 is attached so that the shaft 92 is protruded leftward in the drawing and the lower arm 80 is rotated clockwise.
The work is clamped between the lower electrode 4 and the lower electrode 102. Between the electrodes 102 and 104, a welding current is supplied from a transformer 108 as a welding power source arranged on the support frame 74 via a bracket 106. Spot welding is carried out by applying a welding current while the work is being clamped.

The operation of the electric welding device is controlled by the controller 124 shown in FIG. The controller 124 includes CPU, RAM, R
It is configured to include a microcomputer having an OM or the like, performs signal processing according to a program stored in advance in ROM while utilizing the temporary storage function of RAM, and outputs drive signals SDP, SDM and welding command signal SW. The drive signal SDP is output to the servo amplifier 126 that supplies drive power to the servo motor 90,
For example, the motor current is controlled to control the rotation speed and torque of the servomotor 90. The servo motor 90 includes an encoder 128, and an electrode position signal SXP indicating the rotational position of the encoder 128, that is, the electrode position XP of the lower electrode 102 is supplied to the controller 124 via the servo amplifier 126. The drive signal SDM is output to each servo amplifier 130 that supplies drive power to each of the servo motors 120 of the mobile robot 122, and the drive power is controlled to control the spot welding gun 70 in a preset path. Move with. Each servo motor 120 is provided with an encoder 132, and a rotation position of each servo motor 120, that is, an axis position signal SXM representing the axis position XM of each axis of the mobile robot 122 is sent to the controller 124 via the servo amplifier 130. Supplied. The welding command signal SW is output to the timer contactor 134 connected to the transformer 108, and the transformer 1
The welding current Iw is applied between the upper electrode 104 and the lower electrode 102 only during the welding time Tw from 08. The welding time Tw and the welding current Iw are set in advance in the timer contactor 134 according to the welding conditions.
When the energization ends after the passage of w, the timer contactor 13
The welding completion signal SEW is supplied from 4 to the controller 124. Further, the load signal SL representing the load detected by the load detection sensor 100, that is, the clamping load L between the upper electrode 104 and the lower electrode 102 is sent to the controller 124 via an amplifier or an A / D converter. Supplied.

Such an electric welding apparatus is shown in FIG.
Welding is performed according to the flow chart of 2. At the beginning of welding, the spot welding gun 70 is positioned at a predetermined standby position, and the lower electrode 102 is held at the original position farthest from the upper electrode 104 as shown in FIG. At SA1, the drive signals SDP and SDM are output according to the movement path data stored in advance in the RAM or the like, so that the spot welding gun 70 can be positioned at the first welding site.
22 and the spot welding gun 70
The servomotor 90 is rotationally driven so that the lower electrode 102 approaches the upper electrode 104 to a predetermined welding initial position. These operations are performed in parallel, and the respective movement route data are preset by teaching or the like so as not to interfere with each other. The initial welding position of the lower electrode 102 is set so that the amount of movement during pressure welding is as small as possible.

In step SA2, the drive signal SDP is output to bring the lower electrode 102 closer to the upper electrode 104.
The workpiece is clamped between the and, and the torque of the servomotor 90 is feedback-controlled so that the clamping load L represented by the load signal SL becomes a predetermined set load Lo. This step SA2 is performed after the operation of the mobile robot 122 in step SA1 is completed, and only the lower electrode 102 is moved. However, this movement of the lower electrode 102 can be performed continuously with the movement in step SA1. it can. That is, when the lower electrode 102 reaches the welding initial position after the operation of the mobile robot 122 is stopped, the lower electrode 102 is continuously moved without stopping at the welding initial position to clamp the work. It doesn't matter. Next steps SA3 and SA4
Is substantially the same as steps S4 and S5 in the first embodiment. In step SA5, the servo motor 90 is reversely rotated by the drive signal SDP to drive the lower electrode 102.
Are separated to the initial welding position of step SA1.

Further, steps SA6, SA7, SA8
Is substantially the same as steps S7, S8, and S9 in the first embodiment, and step SA is performed until all welding is completed.
Repeat the execution of 1 or less. When all the welding is completed and the determination in step SA8 is YES, step S8
A9 is executed, the mobile robot 122 moves the spot welding gun 70 to the standby position, and the lower electrode 102 of the spot welding gun 70 is separated to the original position.
The movement at this time is also performed at the same time.

As described above, also in this embodiment, step SA1
Therefore, since the lower electrode 102 of the spot welding gun 70 is moved in parallel with the movement of the spot welding gun 70 by the mobile robot 122, the cycle time is shortened, and the load detection sensor 100 is used for actual measurement. Since the welding is started by detecting the clamping load L and the load control at the time of welding is performed, welding failure due to excess or deficiency of the clamping load L is prevented.

In the present embodiment, of the series of signal processing by the controller 124, the part that executes step SA1 corresponds to the simultaneous movement control means, the part that executes step SA2 corresponds to the pinching control means, and step SA3. The part that executes SA4 and SA4 corresponds to the energization control means.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the above-described embodiment, the case where resistance welding is continuously performed at a plurality of welding portions has been described. However, the work 46 is returned to the delivery position every time one welding is completed, or the spot welding gun is used depending on the welding content. It is of course possible to return 70 to the standby position.

In the above embodiment, the servo motor 40,
Although the material handling robot 38 and the mobile robot 122 driven by 120 are used, they are designed to be operated simultaneously with the pinching robot 10 and the spot welding gun 70.
They can be operated separately, or a mobile robot using an air cylinder or the like as a drive source can be used.

In the above embodiment, one of the electrodes 30, 1
The pinching robot 10 and the spot welding gun 70 for pinching the work by moving 02 are used, but various other pinching robots that relatively bring a pair of electrodes relatively close by using an electric motor as a drive source are provided. The present invention can be similarly applied to an electric welding device.

Although not illustrated one by one, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is a perspective view showing a main part of an electric welding device according to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a control system included in the electric welding device of FIG.

FIG. 4 is a flow chart explaining the operation of the electric welding apparatus of FIG.

5 is a time chart for explaining the state of each part when steps S3 to S6 of FIG. 4 are executed.

FIG. 6 is a flowchart illustrating the specific content of welding determination in step S7 of FIG.

FIG. 7 is a flowchart illustrating another example of welding determination that can be performed during the operation of FIG.

8 is a flow chart in the case of performing electrode wear determination during the operation of FIG.

FIG. 9 is a partially cutaway front view showing a spot welding gun used as a pinching robot in another embodiment of the present invention.

FIG. 10 is a right side view of the spot welding gun of FIG.

FIG. 11 is a block diagram illustrating a control system of the embodiment of FIG.

FIG. 12 is a flowchart illustrating the operation of the embodiment of FIG.

[Explanation of symbols]

 10: Clamping robot 16: Lower electrode 24: Servo motor (electric motor) 28: Load detection sensor 30: Upper electrode 36: Transformer (welding power source) 38: Material handling robot (mobile robot) 40: Servo motor (electric motor) 46 : Work 56: Controller 70: Spot welding gun (clamping robot) 90: Servo motor (electric motor) 100: Load detection sensor 102: Lower electrode 104: Upper electrode 108: Transformer (welding power supply) 120: Servo motor (electric) Motor) 122: mobile robot 124: controller step S1: simultaneous movement control means step S3: clamping pressure control means steps S4, S5: energization control means step SA1: simultaneous movement control means step SA2: clamping pressure control means steps SA3, SA4: Energization control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Amano 6 Toyota Town, Toyota City, Aichi Prefecture, Kyoho Manufacturing Co., Ltd. (72) Inventor, Genichi Nakayama 6 Toyota Town, Toyota City, Aichi Prefecture, Kyoho Manufacturing Co., Ltd. (72) Inventor Takanori Nakamura 1 Toyota-cho, Toyota-shi, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Hideo Narita 1-cho, Toyota-machi, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (2)

[Claims] 1. A pinching robot that pinches a workpiece by bringing a pair of electrodes relatively close to each other using an electric motor as a drive source,
A mobile robot that relatively moves the clamping robot and the work so that a welding portion of the work is located between the pair of electrodes using an electric motor as a drive source, and a welding current is passed between the pair of electrodes. An electric welding apparatus including a welding power source for resistance welding the work, wherein the mobile robot and the pinching robot are simultaneously operated to position a welding portion of the work between the pair of electrodes. Simultaneous movement control means for making a pair of electrodes relatively close to each other, a load detection sensor provided in the pinching robot for detecting a pinching load between the pair of electrodes, and a pair of electrodes for making a pair of electrodes close to each other. While clamping the work, the electric motor of the clamping robot is fed so that the clamping load detected by the load detection sensor becomes a preset load. The pinching control means for controlling the back, and when the pinching load detected by the load detection sensor during the operation control of the pinching robot by the pinching control means reaches a predetermined welding start load, the welding power source An electric welding apparatus comprising: an energization control unit that energizes a welding current between the pair of electrodes. 2. A pinching robot for pinching a workpiece by bringing a pair of electrodes relatively close to each other using an electric motor as a drive source,
An electric welding device comprising: a welding power source for resistance-welding the work by passing a welding current between the pair of electrodes, wherein a pinching load between the pair of electrodes is provided in the pinching robot. And a pair of electrodes are brought close to each other to clamp the work, and the clamping robot detects the clamping load detected by the load detection sensor to be a preset load. Pinching control means for feedback controlling the electric motor, and when the pinching load detected by the load detection sensor during the operation control of the pinching robot by the pinching control means reaches a predetermined welding start load, An electric welding device, comprising: an energization control unit that energizes a welding current from the welding power source between the pair of electrodes.