JPH08206860A - Spot welding method - Google Patents

Abstract

PURPOSE: To obtain a method for spot welding with a small-sized equipment capable of operations in a short time by irradiating a desired spot welding position with a laser beam and melting two or more objects simultaneously for welding. CONSTITUTION: An industrial robot 1 is controllably driven by a controller 4, so that a laser torch 3 in a robot hand 2 is positioned at the spot welding position of an object to be worked. Additionally, the upper hand 2a and the lower hand 2b are driven so as to hold two sheets of object. Then, a command for outputting a laser beam is given to a laser generator by the controller 4, and the target position for a spot welding is irradiated with a laser beam only for a set time by means of the laser torch 3. After the spot welding by melting the object locally, the upper hand 2a and the lower hand 2b are opened, ending the welding operation. An adjustment is made preliminarily concerning the injection of a gas from the nozzle of the laser torch 3, the adjustment of the focal position and the irradiation time of the laser, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in spot welding methods.

[0002]

2. Description of the Related Art Resistance welding is known as a welding method used for spot welding. In this welding method, two work materials are polymerized, sandwiched between two electrodes in which cooling water is circulated, and the electrodes are strongly pressed to flow a large current to generate Joule heat, thereby processing the work. Spot welding is performed by melting each of the materials, in particular, only the vicinity of the contact surface between the materials to be processed by the cooling effect of the cooling water.

A general example of the configuration required to perform resistance welding is shown in FIG. In FIG. 3, reference numeral 100 is a spot welding robot, and a spot welding gun 101 is attached to the arm tip thereof. The spot welding gun 101 has electrodes 102 and 103 for strongly pressing the superposed two workpieces, and one electrode 103 is switched to the other by a command from a control device 106 that drives and controls the spot welding robot 100. The electrode 102 can be driven so as to come into contact with and separate from the electrode 102. Reference numeral 104 is a welding transformer that provides a machining power supply to the electrodes 102 and 103, and the energization time is controlled by a spot welding timer 105 that operates for a set time in response to an operation command from the control device 106. A balancer 107 has a function as a mass balance for supporting a part of the weight of the spot welding gun 101 and reducing an operating force.

The resistance welding process is performed as follows. First, the control device 106 causes the spot welding robot 10
0 is driven and controlled to position the spot welding gun 101 at the spot welding position of the workpiece, and the electrodes 102 and 10
3 is driven to grip the two workpieces with high pressure. Next, the control device 106 operates the spot welding timer 105 to apply a processing power supply to the electrodes 102 and 103 for a predetermined time, performs spot welding by resistance welding, and then confirms that the operation of the spot welding timer 105 is completed. Electrode 1
02 and 103 are opened and the welding operation is completed.

The above is the normal sequence operation for one welding spot. When there are a large number of spot welding spots, the control unit 106 successively determines the positioning target position (spot welding position) of the spot welding gun 101 from the machining program. The sequence operation similar to the above is repeatedly executed at each welding position.

However, when the resistance welding is repeatedly performed on many spot welding points, the electrodes 102 and 1
When the tip of 03 is consumed and deformed due to pressure, energization, or the like, the contact area of the electrodes 102 and 103 with respect to the work material changes, and the current per unit area flowing in the welded part changes. Normal welding work may not be possible. Therefore, equipment for dressing work for adjusting the shapes of the electrodes 102 and 103 is required,
There is a problem that the peripheral equipment becomes large. In addition, since the dressing work is performed every time the electrodes 102 and 103 are consumed and the welding work must be stopped during that period, there is also a problem in work efficiency.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, to perform spot welding work efficiently without requiring equipment for dressing work. To provide.

[0008]

SUMMARY OF THE INVENTION The present invention is a spot welding method in which two or more workpieces are polymerized and welded, by irradiating a desired spot welding position with a laser so that the two or more workpieces are jointly welded. The above object has been achieved by a structure characterized by melting and welding.

A laser torch is integrally attached to a robot hand having a gripping function, and welding work is performed while two or more workpieces are pressure-welded by the robot hand, so that spot welding work can be carried out efficiently and continuously. I was able to do it.

By using a YAG laser,
Only the torch of the laser can be attached to the robot hand separately from the laser oscillator so that the robot hand can be moved efficiently and lightly.

[0011]

The robot hand is positioned at the spot welding position, two or more workpieces in the overlapped state are grasped, and a laser is radiated from the laser torch attached to the robot hand toward the spot welding position. Spot welding is performed by melting the processed material.

Since non-contact welding work is performed by utilizing the melting of the work material caused by laser irradiation, wear or wear does not occur in the working means even if spot welding is repeatedly executed, and deformation due to wear or wear is corrected. Since the dressing work for performing the welding is unnecessary, the spot welding can be continuously performed without resting the welding work.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an outline of a spot welding system of an embodiment for carrying out the method of the present invention. In FIG. 1, reference numeral 1 is an industrial robot that is also used as a spot welding robot or the like, and a YAG laser laser torch 3 is attached to a robot hand 2 attached to the end of the arm. The robot hand 2 has an upper hand 2a and a lower hand 2b for gripping two or more overlapped workpieces, and the upper hand 2a is instructed by a control device 4 for driving and controlling the industrial robot 1. The lower hand 2a and the lower hand 2b are opened and closed. Reference numeral 5 is Y
It is a laser oscillator of an AG laser and is connected to the laser torch 3 by a fiber cable 6. The ON / OFF control of the laser output of the laser oscillator 5 is performed by the control device 4
It is done by the command from.

As shown in FIG. 2 (a), the laser torch 3 is attached to the upper hand 2a while being displaced from the grip portion located at the tip of the upper hand 2a, and in FIG. 2 (b).
In some cases, it is directly embedded in the grip portion located at the tip of the upper hand 2a, as shown in FIG. The former is advantageous in protecting the robot hand 2 when the workpiece is heated to a considerably high temperature, and the latter is advantageous in ensuring the positioning accuracy of the spot welding position.

If there is a deviation between the gripping reference position of the robot hand 2 and the mounting position of the laser torch 3, the teaching operation is performed with reference to the mounting position of the laser torch 3, and the industrial robot is used. In the case where the robot hand 2 is positioned by the sensor means provided in 1 or the industrial robot 1 is driven and controlled only by numerical program control by omitting the teaching operation, the controller 4 is caused to use this deviation as a correction value. By storing the information, normal positioning control is performed based on the mounting position of the laser torch 3.

The gripping function of the robot hand 2 is sufficient if it has a force enough to bring two or more workpieces into close contact with each other (strong pressure gripping for securing energization is not required as in the case of resistance welding).

The process of spot welding using this system is performed as follows.

First, the control device 4 drives and controls the industrial robot 1 to position the laser torch 3 of the robot hand 2 at the spot welding position of the work material, and drives the upper hand 2a and the lower hand 2b. 2 (a) or FIG.
As shown in (b), the two workpieces 7 and 8 are held. Next, the control device 4 gives a laser output command to the laser oscillator 5, causes the laser torch 3 to irradiate the target position of spot welding with laser for a set time, and locally melts the workpieces 7 and 8 to perform spot welding. After going
The upper hand 2a and the lower hand 2b are opened, and the welding operation is completed. Regarding the amount of gas ejected from the nozzle of the laser torch 3, the adjustment of the laser focus position, the irradiation time, etc., in order to obtain deep penetration suitable for spot welding,
The materials 7 and 8 to be processed are adjusted in advance according to their types and thicknesses.

The above is the sequence operation for one spot welding spot. Further, if there are many spot welding points, the positioning target position (spot welding position) of the robot hand 2 is called one after another, and the same sequence operation as above is repeatedly executed at each welding position.

Since the spot welding is not performed by using the processing means that is consumed as in the case of resistance welding, the dressing work of the processing means is performed even when the spot welding is repeatedly performed on many welding points. Is not necessary,
A large number of welding points can be continuously spot-welded.

Further, in the case of the YAG laser, a fiber cable can be used, and since only the laser torch 3 needs to be attached to the robot hand 2, the equipment of the robot hand 2 can be lightened and its operation can be performed smoothly, and balance adjustment can be performed. No balancer means are needed. Further, since it is not necessary to strongly press the workpieces 7 and 8 to secure the energization, the gripping ability of the robot hand 2 is not required to be excessive.

As an example, the YAG laser is used as the stationary laser oscillator 5 and the laser beam is transmitted to the laser torch 3 through the fiber cable 6, but in the case of other lasers, the industrial robot is used. It is also possible to incorporate a mirror in the joint part 1 or the like to transmit the laser light.

[0023]

Since the spot welding method of the present invention does not require an electrode for welding work, equipment for dressing work is not required, and the equipment required for spot welding is downsized as a whole. Further, since it is not necessary to stop the welding work for correcting the shape of the electrode, the work can be performed in a short time even when spot welding is performed on many welding points.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of a spot welding system of an embodiment for carrying out the method of the present invention.

FIG. 2 is a diagram conceptually showing an example of mounting a laser torch on a robot hand.

FIG. 3 is a diagram showing a general example of a configuration required for performing resistance welding (conventional example of spot welding).

[Explanation of symbols]

 1 Industrial Robot 2 Robot Hand 2a Upper Hand 2b Lower Hand 3 Laser Torch 4 Controller 5 Laser Oscillator 6 Fiber Cable 7, 8 Work Material 100 Spot Welding Robot 101 Spot Welding Gun 102 Electrode 103 Electrode 104 Welding Transformer 105 Spot Welding Timer 106 control device 107 balancer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryo Nihei 3580, Kobaba, Oshinomura, Minamitsuru-gun, Yamanashi Prefecture, within FANUC Co., Ltd. Local FANUC Co., Ltd.

Claims (3)

[Claims] 1. A spot welding method in which two or more workpieces are polymerized and welded, wherein a desired spot welding position is irradiated with a laser, and the two or more workpieces are melted together and welded. And spot welding method. 2. The spot welding according to claim 1, wherein a laser torch is integrally attached to a robot hand having a gripping function, and the welding work is performed while the two or more workpieces are pressed by the robot hand. Method. 3. The spot welding method according to claim 1, wherein a YAG laser is used as the laser.