JPH05261558A - Spot welding machine - Google Patents

Abstract

PURPOSE:To execute an accurate pressure control and to make the welding highly precise by rotating an operation rod by a drive motor to open and close a welding gun and controlling the pressure of the welding gun. CONSTITUTION:The welding gun 2 is equipped in the front end part of a spot welding equipment 1. A work is pressure-clamped by a pair of welding electrodes 11, 12 capable of opening and closing the welding gun 2. Further, the drive motor 14 and the operation rod 15 which are communicated with each other are provided. This operation rod 15 and the base end part of welding gun are joined through a screw. The operation rod 15 is rotated by the drive motor 14 to open and close the welding gun 2 and to control pressure. Consequently, the welding gun 2 is smoothly opened and closed, and the pressure control is made in real-time and high-precision by controlling the number of rotation of the drive motor 14 and the opening state of the welding gun 2 can be taught freely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot welding device.

[0002]

2. Description of the Related Art Conventionally, a robot has been used for spot welding a work to be welded by a spot welding device, a welding gun is attached to the robot, and the work is fixed to a supporting device or the like. .. When performing welding work, the robot moves the welding gun, then opens the welding gun and positions it at the welding point of the workpiece.The welding gun is closed and the workpiece is pressed and held by a pair of welding electrodes. In this state, a welding current is supplied to perform spot welding.

By the way, an air cylinder is generally used as an opening / closing actuator of a spot welding gun used in a robot control type and a portable type, and a hydraulic cylinder is a large machine such as a multi-welding device (spot welding, stud welding). It is used only for stationary devices. This is because the air cylinder is lighter in weight than the hydraulic cylinder, which is advantageous for the usage method of moving the welding gun itself. Also, since a large force is not required to open and close the welding gun, the welding gun can be opened and closed sufficiently even with an air cylinder. Further, the air circuit is simpler than the hydraulic circuit, and the air to be used is easily supplied by the arrangement from the centralized air source of the factory, so that the structure of the device can be simple and lightweight. .. Moreover, since the robot moves violently, the pipes are often damaged, and even if the pipes are damaged, if the air leaks, the surroundings will not be affected so much.

[0004]

However, when an air cylinder is used as the actuator for opening and closing the welding gun, stroke adjustment is difficult due to the compressibility of the air, so the opening of the welding gun can be adjusted freely. It was impossible to control, and the opening of the welding gun had to be controlled by providing a complicated variable stopper. Therefore, since the open position of the welding gun can take only two positions, "large" and "small", the pressurizing time becomes long when the open position does not have to be large. In addition, in places where you want to enter the welding gun around the middle position of the large opening and the small opening, you can not weld unless you use another welding gun, so many types of welding guns are required, which causes high cost have.

Further, since the pressurization of the welding gun to the work is controlled by the pressure of the compressed air, a delay occurs in the control, the cycle time becomes long, and the operation of the welding gun deteriorates at low pressure. There is a drawback that the cycle time becomes longer and the efficiency of welding work cannot be improved. If a hydraulic cylinder is used instead of the air cylinder, the opening and pressure of the welding gun can be controlled freely, but the disadvantages of using a hydraulic cylinder are even greater. It is not suitable to be used for the open / close actuator of.

The present invention has been made in view of such circumstances, and an object thereof is to speed up and stabilize the opening and closing operation of the welding gun, and to freely set the opened state of the welding gun. The purpose of the present invention is to provide a spot welding apparatus capable of controlling the pressing force immediately.

[0007]

In order to solve the problems of the above-mentioned prior art, in the present invention, an openable and closable welding gun for pressing and holding a work by a pair of welding electrodes provided at the tip portion, A driving motor and an operating rod connected to each other are provided, the operating rod and the base end portion of the welding gun are screwed together, and the operating rod is rotationally driven by the driving motor to open and close the welding gun,
It is configured to control the pressing force of the welding gun.

[0008]

[Operation] In the spot welding apparatus according to the present invention, a drive motor and an operation rod are used, and the operation rod is rotationally driven by the drive motor to open and close the welding gun screwed to the operation rod and Since the welding pressure is controlled, the opening and closing operation of the welding gun is smooth, and the control of the rotation speed of the drive motor enables real-time pressurization control and high accuracy, and the opening state of the welding gun can be freely taught. It becomes possible to do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 shows an embodiment of the spot welding apparatus according to the present invention. In the figure, reference numeral 1 denotes a spot welding apparatus, which is a welding gun 2 attached to a gun holding robot (not shown), a support bracket 3 for supporting the welding gun 2, and the welding guns 2 and A robot controller 4, a welding timer contactor 5, and a gun controller 6 arranged in association with the support bracket 3 are provided respectively.

In the welding gun 2, the intermediate portions 8a and 9a are provided in the U-shaped mounting bracket 7 extending downward and the support pin 10 is provided.
It has a pair of upper and lower gun arms 8 and 9 which are rotatably attached via the. Arms 8 and 9 are provided with welding electrodes 11 and 12, respectively. On the other hand, the support bracket 3 is formed by using a plate-shaped body having an L-shaped cross section in which the upper surface portion 3a is bent substantially horizontally, and the speed reducer 13 and the AC servomotor (drive motor) are formed below the side surface portion 3b. ) 14 is attached along the vertical direction. The upper portion of the mounting bracket 7 is fixed to a gun holding robot (not shown).

Further, on the support bracket 3, an operation rod (screw rod) 15 is provided on the side surface portion 3 of the support bracket 3.
The operation rod 15 is provided in parallel with and spaced from it, and a ball screw which is a male screw is formed on the outer peripheral surface of the operation rod 15. Therefore, the upper end portion of the operation rod 15 is rotatably attached to the upper surface portion 3 a of the support bracket 3, and the lower end portion is connected to the servomotor 14 via the speed reducer 13, and the operation rod 15 is connected by the servomotor 14. Are configured to be rotationally driven.

On the other hand, the base end portion 8c of the upper gun arm 8 constituting the welding gun 2 is screwed to the operation rod 15 via the tubular member 16. The tubular member 16 includes a cylindrical portion 16a that moves along the axial direction on the operation rod 15 that is rotationally driven, and a support portion 16b that is provided so as to project on the outer peripheral surface of the cylindrical portion 16a. A female screw that engages with the ball screw of the operating rod 15 is formed on the peripheral surface. Further, the support portion 16b is formed in a substantially U shape having opposing pieces, and the base end portion 8c of the upper gun arm 8 is rotatably supported by the engagement pin 17 between the opposing pieces. Further, the base end portion 9c of the lower gun arm 9 has the facing piece 1
It is attached to the speed reducer 13 via a U-shaped member 18 having 8a. The U-shaped member 18 is integrally projectingly provided on the outer peripheral surface of the speed reducer 13, and the base end portion 9c of the lower gun arm 9 is rotatably supported by the engagement pin 19 between the facing pieces 18a. ..

The welding gun 2 is constructed so that it can be opened and closed by vertically moving the base end portions 8c and 9c of the upper and lower gun arms 8 and 9 and pivoting the support pin 10 as a center. The tip portions 8b and 9b of 8 and 9 are moved up and down to hold a work (not shown) between the welding electrodes 11 and 12 under pressure. Further, the welding gun 2 is provided with a damper device 20, and the damper action of the damper device 20 prevents the shocking opening / closing operation of the welding gun 2.

The welding gun 2 and the welding timer contactor 5 are connected via a control cable 21, and the servomotor 14 and the gun controller 6 are connected via a control cable 22. Also, robot control 4
And the gun controller 6 are connected via a control cable 23, and the welding timer contactor 5 and the gun controller 6 are connected via a control cable 24.

In order to perform spot welding of a work (not shown) using the spot welding apparatus of this embodiment, first, the robot controller 4 outputs a gun opening command signal and a welding command signal and sends them to the gun controller 6. .. The gun controller 6 that has received the gun opening command signal controls the servo motor 14 based on this command signal, and drives the servo motor 14 accordingly. When the servo motor 14 is driven, the speed reducer 13 and the operating rod 15 also rotate in conjunction with each other, and accordingly, the tubular member 16 causes the operating rod 1 to move.
5, the welding gun 2 moves downward along the axial direction in the drawing, and the welding gun 2 operates in a pre-teaching gun open state.
Then, a gun holding robot (not shown) is moved to insert a work (not shown) between the welding electrodes 11 and 12, and the work is placed at a predetermined welding point position.

Next, the gun controller 6 controls and drives the servomotor 14 on the basis of the welding command signal, and at the same time rotates the reduction gear 13 and the operating rod 15 in the direction opposite to the above-described rotation direction. Along with this, the tubular member 1
6 moves upward along the axial direction of the operating rod 15, the welding gun 2 closes and is in a pressurized state, and the welding electrodes 11, 12
Holds the work with a controlled pressing force. When the designated pressure is applied, the gun controller 6 outputs a welding designation signal to the welding timer contactor 5, supplies welding current to the welding gun 2 and energizes between the welding electrodes 11 and 12 to perform spot welding on the joint surface of the workpiece. To do. Then, the gun controller 6 waits for the input of the welding completion signal from the welding timer contactor 5, drives the servo motor 14 in the same manner as described above, opens the welding gun 2, and creates a pre-teaching gun open state. An OK signal that enables transition to the next step operation is sent to the controller 4. After that, the above operation is repeated again to sequentially perform spot welding at necessary welding point positions of the work, and the predetermined welding process is completed.

In the spot welding apparatus 1 of this embodiment, the operating rod 15 screwed to the welding gun 2 through the tubular member 16 is rotationally driven by the servomotor 14 to pressurize the welding gun 2. Therefore, the pressurization control can be performed in real time, and the opening / closing operation of the welding gun 2 is fast and stable. In addition, since the speed can be reduced by controlling the rotation speed of the servo motor 14 when the welding gun 2 is pressurized, it is possible to reduce the hammer noise during the pressurization, which is impossible with the conventional air cylinder. .. In addition to this, since it is possible to teach the gun freely even when the gun is open, it is possible to reduce unnecessary operations from robot teaching.

The embodiment of the present invention has been described above.
The present invention is not limited to the embodiments described above, and various modifications and changes can be made based on the technical idea of the present invention.

For example, in the above-described embodiment, the servo motor 1
4, the operating rod 15 was rotationally driven, but if the rotational motor is configured to detect the amount of rotation (gun opening stroke) and the driving force of the operating rod 15 and operate by feedback, the type of the driving motor It doesn't matter.

[0021]

As described above, the spot welding apparatus according to the present invention comprises the welding gun which can be opened and closed, the drive motor and the operating rod which are connected to each other, and the operating rod and the base end portion of the welding gun are screwed together. Combined, the drive motor rotates the operating rod to open and close the welding gun,
Since it is configured to control the pressure of the welding gun, it is possible to perform accurate pressurization control in real time, achieving high precision and welding in a quiet environment by reducing the hammer noise during pressurization. You can do the work. Moreover, in the spot welding apparatus of the present invention, the opening and closing operation of the welding gun becomes smooth, the operation can be speeded up and stabilized, and unnecessary operation can be reduced by freely setting the gun open state. As a result, the efficiency of welding work can be significantly improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a spot welding apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 Spot Welding Device 2 Welding Gun 3 Support Bracket 8 and 9 Gun Arm 10 Support Pin 11 and 12 Welding Electrode 13 Speed Reducer 14 Servo Motor 15 Operating Rod 16 Cylindrical Member 17 and 19 Engagement Pin 18 U-shaped Member

Claims (1)

[Claims] 1. A welding gun, which holds a work under pressure by a pair of welding electrodes provided at a tip end thereof, and an openable and closable welding gun, and a drive motor and an operating rod which are connected to each other. A spot welding apparatus, which is configured to be screwed to an end portion, rotationally drive the operation rod by the drive motor to open / close the welding gun, and control the pressing force of the welding gun.