JP2009018326A - Apparatus for laser spot welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in resistance spot welding, the generation of spatter (dispersion) cannot be completely prevented and causes the erroneous operation of peripheral members, and in laser spot welding, required welding strength cannot be achieved when the contact degree between workpieces W, W is low. <P>SOLUTION: In the apparatus of laser spot welding, hollow cylindrical tips 1a, 1b are provided so as to press the workpieces W, W from both sides of the workpieces W, W. The tip end 20 of a glass fiber 2 capable of radiating a laser beam is provided inside one hollow cylindrical tip 1a at specified distance from the end 10 of the cylinder, and also degassing holes 3 are provided on the side wall surface of the hollow cylindrical tip 1a, and a heat sensor 5 is provided inside the other hollow cylindrical tip 1b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser spot welding apparatus that welds materials to be welded (workpieces) such as steel plates using a laser at a manufacturing site such as an automobile manufacturing factory.

  In an automobile production assembly line, resistance spot welding and laser welding are known for welding between workpieces such as steel plates.

  Various methods are known for resistance spot welding, and welding is performed by applying a voltage from both sides to a spot portion between two workpieces to be welded and utilizing the electrical resistance of the workpiece.

  In laser spot welding, the spot portion is welded by laser radiation by accessing from one side of the spot portion between two workpieces to be welded.

  However, resistance spot welding is likely to generate spatter (spattering), and spatter generation cannot be reduced to zero. For this reason, there is a problem that spatter is attached to the jig movable part, and there is a defect that spatter adheres to the sensor and the function of the original sensor cannot be performed, resulting in malfunction.

  Laser spot welding, unlike resistance spot welding, has the advantage that it does not generate spatter, has high flexibility in the welded part because it is accessed from one side, and has good product accuracy because it is less affected by heat.

  However, the conventional laser spot welding (see FIG. 4) has a drawback that welding with the required strength cannot be performed when the adhesion between the two workpieces W and W is low due to access from one side. Furthermore, since it is necessary to keep the distance D between the transmitting portion of the laser L and the workpiece W constant, the accuracy of the installation position of the workpiece and the accuracy between the workpieces are necessary, and thus a workpiece fixing jig is necessary.

  In order to solve the above-mentioned problem, a hollow cylindrical tip capable of pressurizing the workpiece from both sides of the workpiece is provided, and the tip of the glass fiber capable of transmitting a laser is placed at a constant distance from the cylindrical end in the hollow cylindrical tip on one side. A laser spot welding apparatus is proposed in which a plurality of vent holes are formed in the side wall surface of the hollow cylindrical tip, and a thermal sensor is provided in the hollow cylindrical tip on the other side.

  Further, the laser spot welding apparatus described in the column 0008, in which the hollow cylindrical tip is provided with a material that does not allow laser light to pass therethrough, is proposed.

  A laser spot welding apparatus as described in columns 0008 or 0009, in which two hollow cylindrical tips are provided in a servo gun of a servo pressurization unit, is proposed.

  According to the present invention, since the laser transmitting portion is provided in the hollow cylindrical tip and is provided at a fixed interval from the cylindrical end portion, the spatter is not scattered at all. The effect of complete sputtering is as follows. Since the spatter does not adhere to the jig movable part and the peripheral sensor, the malfunction of the jig movable part and the peripheral sensor is eliminated. Since spatter does not adhere, the life of the drive chain, LM rail, etc. is extended. The quality of the coating has been improved because the amount of iron powder brought into the painting factory has decreased. In addition, since a magnetic field generated during resistance spot welding is not generated, malfunctions of peripheral sensors (such as confirmation of workpiece adhesion) are eliminated. The water pipe that was necessary for cooling became unnecessary.

  Since the spot welded portion is sandwiched by hollow cylindrical tips from both sides, the lack of adhesion between the workpieces, which was a drawback of conventional laser spot welding, can be prevented, and the welding accuracy has been improved.

  Furthermore, since the laser transmitter is fixedly arranged at a fixed interval from the end of the hollow cylindrical tip, the laser transmitter can be reliably held at a constant distance between the workpiece and the laser spot welding with high accuracy. Can now.

  Compared with resistance spot welding, the transformer and the cooling hose are not required, and the servo gun can be reduced in size and weight because the pressure applied from both sides to the workpiece by the servo gun is only the workpiece adhesion force. This makes it easier to install and move.

  In addition, non-contact welding eliminates the risk of welding, enabling high-speed movement between spot welds.

  Furthermore, in conventional laser spot welding, it was necessary to install a protective enclosure around the entire process in order to protect the operator's eyes from the ultraviolet rays of the YAG laser. In this invention, the material through which the laser does not pass is provided. Since it is hermetically sealed by forming with, it is no longer necessary to install a protective enclosure.

  Next, FIG. 1 which is a perspective explanatory view of a laser spot welding apparatus according to an embodiment of the present invention, FIG. 2 which is also an enlarged explanatory view of the main part, FIG. 3 which is a perspective explanatory view of conventional resistance spot welding, and FIG. A description will be given based on FIG. 4 which is an enlarged explanatory view of a main part of laser spot welding.

  The laser spot welding apparatus according to an embodiment of the present invention includes two hollow cylindrical chips 1a and 1b that can pressurize the workpieces W and W from both sides of the workpieces W and W that are two steel plates. The two hollow cylindrical chips 1a and 1b are respectively installed as members of the servo pressurizing unit 4, and have a configuration capable of holding the workpieces W and W as welded members between the end portions thereof. The two hollow cylindrical tips 1a and 1b are made of metal, and the inner diameter of the cylinder is about 25 mmφ.

  The hollow cylindrical tip 1a on one side is provided with a material capable of transmitting a laser inside the hollow, glass fiber 2 in this embodiment, and the tip 20 of the glass fiber 2 is fixed at a fixed interval from the cylindrical end 10. Provided. In this embodiment, the material 2 capable of transmitting a laser is glass fiber.

  The hollow cylindrical tip 1a is provided with a plurality of gas vent holes 3 as through holes in the vicinity of the side wall surface where the tip 20 of the glass fiber 2 is located. The diameter of the vent holes 3 is about 1-2 mm, and the number is about 8-10 at equal intervals in the circumferential direction.

  A heat sensor 5 is fixedly provided in the hollow cylindrical chip 1b on the other side. The thermal sensor 5 is fixedly provided in the vicinity of 2 to 3 mm from the end of the hollow cylindrical tip 1b.

  The two hollow cylindrical tips 1 a and 1 b are provided by being attached to the servo gun 40 of the servo pressurizing unit 4. The servo pressurizing unit 4 is a device in which the transformer T and the cooling water hose H are removed from the servo gun used for resistance spot welding. To do. The servo pressurizing unit 4 is smaller than the resistance press welding servo pressurizing unit.

  An inert gas supply hose 6 passes through the servo pressurizing unit 4 and communicates with the hollow cylindrical tip 1a.

  Next, the operation of the laser spot welding apparatus according to the embodiment of the present invention will be described. The workpieces W and W, which are members to be welded such as steel plates, are sandwiched between the tip portions 10 and 10 by two hollow cylindrical chips 1a and 1b attached to the servo gun 40 of the servo pressurizing unit 4 and are brought into pressure contact. As a result, the distance between the workpiece W and the tip 20 of the glass fiber 2 which is a laser transmitter is kept constant.

  In this state, laser L is transmitted from the tip 20 of the glass fiber 2 to perform spot welding of the workpieces W and W. Whether or not the welding has been completed is determined by detecting whether or not the spot weld has heated to a certain temperature by detecting the heat sensor 5 provided on the other hollow cylindrical tip 1b. When the thermal sensor 5 senses a predetermined temperature, it sends a welding completion signal to notify it.

  Even if spatter is generated during welding, it remains in the hollow cylindrical tip 1a and does not go outside. At the time of welding, the inert gas G is supplied from the inert gas supply hose 6 through the hollow cylindrical tip 1a to the welding site, and the inert gas G is discharged from the gas vent hole 3 to the outside.

  The present invention is used as a spot welding apparatus in a manufacturing site where work spot welding is performed such as an automobile manufacturing assembly line.

A perspective view of laser spot welding according to an embodiment of the present invention Similarly, the main part enlarged explanatory drawing Perspective view of conventional laser spot welding Explanatory drawing of the main part of conventional laser spot welding

Explanation of symbols

1 Hollow cylindrical tip 10 Cylindrical tip 1a Hollow cylindrical tip (with glass fiber)
1b Hollow cylindrical tip (with thermal sensor)
2 Laser transmission material (glass fiber)
20 Material edge (glass fiber edge)
3 Degassing hole 4 Servo pressure unit 40 Servo gun 5 Thermal sensor 6 Inert gas supply hose
W Work L Laser H Cooling water hose T Transformer G Inert gas D Distance

Claims (3)

  A hollow cylindrical tip capable of pressurizing the workpiece from both sides of the workpiece is provided, and the tip of the glass fiber capable of transmitting a laser is provided at a certain distance from the cylindrical end in the hollow cylindrical tip on one side and the hollow cylindrical tip A laser spot welding apparatus characterized in that a plurality of vent holes are formed in the side wall surface, and a thermal sensor is provided in the hollow cylindrical tip on the other side.   The laser spot welding apparatus according to claim 1, wherein the hollow cylindrical tip is provided with a material that does not allow laser light to pass therethrough.   The laser spot welding apparatus according to claim 1 or 2, wherein two hollow cylindrical tips are provided in a servo gun of a servo pressurizing unit.

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