JP2010110767A - Spot welding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spot welding device which welds a workpiece (a material to be welded) from one side and maintains stable welding quality. <P>SOLUTION: The laser spot welding device makes a laser beam output from a laser oscillator converge and irradiates the beam to the materials to be welded (the workpieces W1, W2) having overlapped metal sheets. The laser spot welding device includes: a body 12 formed into a hollow cylinder with an opened lower end and having an upper end attached with an optical fiber for guiding the laser beam output from the laser oscillator; a lid 20 closing the opening at the lower end side of the body 12 and having translucency; a focusing optical system means 25 mounted in the cylinder of the body 12, converging the laser beam from the optical fiber cable 40, and irradiating the converged laser beam to the materials to be welded (the workpieces W1, W2) through the lid 20; and an electro magnet 30 mounted at the outer circumferential part at the lower end side of the body 12 and having a predetermined magnetic force. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spot welding apparatus.

Spot welding is often used in production lines such as automobiles. There are various methods for spot welding, but direct spot welding is generally used to weld and join workpieces by passing a large current while pressing the workpiece with metal plates stacked between the upper and lower welding electrodes. Widely used in
However, for example, at the joint portion of the body of an automobile, it may be difficult to sandwich the workpiece between the upper and lower welding electrodes due to vehicle design and functional reasons, and direct spot welding may not be possible.
Therefore, conventionally, a one-side welding technique for welding a workpiece from one side has been proposed.

For example, as a technique for welding a workpiece from one side, a one-side resistance spot welding system as shown in FIG. 4 has been proposed.
As illustrated, the one-side resistance spot welding system B is opposed to the industrial robot 2 having the robot arm 2a, the welding gun 100 having the welding electrode 110 attached to the tip of the robot arm 2a, and the welding electrode 110. A receiving electrode 150 arranged at a position, a welding electrode 110 and a transformer 160 for supplying a welding current to the receiving electrode 150 are provided.
Then, the one-side resistance spot welding system B moves the welding gun 100 by the industrial robot 2 and sandwiches and presses the workpieces W1 and W2 by the welding electrode 110 and the receiving electrode 150 of the welding gun 110 to generate current. The workpieces W1 and W2 are welded by energizing them.

Further, as a technique for welding a workpiece from one side, a configuration of a laser welding apparatus that performs welding by irradiating a workpiece with a laser beam is known.
Here, a laser welding apparatus according to the prior art will be described with reference to FIG.
As shown in FIG. 5, a laser welding apparatus 400 according to the prior art includes a laser transmitter (not shown) that generates a laser beam, and a lens 415 that focuses and irradiates the laser beam from the laser transmitter (not shown). And a laser head 410 mounted thereon.
The laser head 410 is disposed above the workpieces W1 and W2 such as plated steel plates to be welded, and irradiates a laser beam from above the workpieces W1 and W2 to weld the workpieces W1 and W2.

In the conventional laser welding, a laser beam is emitted from the laser head 410 after a predetermined gap d is provided between the workpiece W1 and the workpiece W2.
As described above, the gap d is provided between the workpiece W1 and the workpiece W2. The reason is that the gas explodes by securing an escape path for the gas stored between the workpiece W1 and the workpiece W2. It is for suppressing.
As shown in FIG. 5, a laser welding method for irradiating a laser beam from the laser head 410 with a gap d provided between the workpiece W1 and the workpiece W2 is disclosed in, for example, Patent Document 1. ing.
JP 7-155974 A

However, the above-described conventional technology has the following technical problems.
Specifically, in the conventional one-side resistance spot welding system B shown in FIG. 4, the welding electrode 110 of the welding gun 100 is moved to the position of the receiving electrode 150 by the industrial robot 2. The alignment between 110 and the receiving electrode 150 is troublesome, and it is difficult to perform the alignment with high accuracy. As a result, the above one-side resistance spot welding system B has a technical problem that the welding quality is not stable.
In the one-side resistance spot welding system B described above, the receiving electrode 150 that presses the welding electrode 110 is disposed on the back surface of the workpiece. However, depending on the shape of the workpiece, the receiving electrode 150 may be difficult to install.

In addition, the prior art laser welding apparatus 400 shown in FIG. 5 can suppress the gas explosion to some extent by providing the gap d between the workpiece W1 and the workpiece W2, but completely prevents the gas explosion. It was difficult to maintain stable welding quality. Moreover, even if the laser welding apparatus 400 of the prior art provided the gap d, it was not possible to prevent boiling of the welding surface, thereby deteriorating the welding quality.
In addition, since laser welding according to the prior art performs laser welding in an atmosphere filled with a shielding gas in order to prevent oxidation, equipment for laser welding has become expensive.
There are CO2 welding and TIG welding as methods for welding workpieces from one side. However, these methods cannot be used to close gaps between workpieces to be welded, so that the welding quality varies. Has technical challenges.

  The present invention has been made to solve the above technical problem, and an object of the present invention is to perform spot welding capable of maintaining stable welding quality in a spot welding apparatus for welding a workpiece (workpiece to be welded) from one side. To provide an apparatus.

The present invention for solving the above problems is applied to a spot welding apparatus that focuses a laser beam output from a laser transmitter and irradiates an object to be welded on which metal plates are stacked.
The spot welding device is formed in a hollow cylindrical shape having an open lower end portion, and a main body portion to which an optical fiber for guiding a laser beam output from the laser transmitter is attached to the upper end portion; A light-transmitting lid that closes the opening at the lower end of the main body, and a laser beam that is provided in the cylinder of the main body and focuses the laser beam from the optical fiber, and the focused laser passes through the lid It is characterized by comprising focusing optical system means for irradiating a beam toward the workpiece and an electromagnet having a predetermined magnetic force attached to the outer peripheral portion on the lower end side of the main body portion.

As described above, in the spot welding apparatus of the present invention, the electromagnet having a predetermined magnetic force is attached to the outer peripheral portion on the lower end side of the main body that irradiates the workpiece to be welded with the metal plates. In addition, the opening at the lower end of the main body is closed by a light-transmitting lid, and a laser beam is applied to the workpiece through the lid.
With this configuration, when welding, the spot welding apparatus of the present invention can closely adhere the work to be welded with the metal plates by the magnetic attraction force of the electromagnet (that is, the weld surface of the work to be welded is in close contact). Can be in a state).
According to the spot welding apparatus of the present invention, the welded surface is in a state where the welded surface of the workpiece is in close contact, and the lid is directly pressed from above on the welded portion of the workpiece. Since an object can be irradiated with a laser beam, boiling and explosion of a welded surface of an object to be welded can be prevented during welding, and welding quality can be stabilized.
That is, according to the present invention, in addition to the magnetic attractive force of the electromagnet, the lid that covers the opening at the lower end of the main body can directly pressurize the welded portion of the workpiece to be irradiated with the laser beam. The explosion that occurs on the welding surface of the workpiece can be effectively prevented.

Moreover, since the laser beam can be prevented from leaking by irradiating the laser beam in a state in which the work piece on which the metal plates are stacked is in close contact, the shield gas is not used as in the conventional laser welding apparatus described above. Need not be used (equipment cost is reduced).
That is, according to the present invention, in addition to the magnetic attractive force of the electromagnet, the lid that covers the opening at the lower end of the main body can directly pressurize the welded portion of the workpiece to be irradiated with the laser beam. The welded part of the work piece can be tightly adhered, thereby preventing leakage of the laser beam.
Furthermore, since the present invention does not require the positioning of the welding electrode 110 and the receiving electrode 150 unlike the one-side spot welding apparatus shown in FIG. 4 described above, the labor of the welding operation is reduced. Also, robot teaching is simplified when the laser spot welding apparatus of the present invention is mounted on an industrial robot.

The electromagnet is preferably a superconducting magnet.
By using a superconducting magnet in this way, it is possible to closely attach an object to be welded on which metal plates are stacked with a strong magnetic force.

  Thus, according to the present invention, it is possible to provide a spot welding apparatus capable of reducing the weight and improving workability and maintaining stable welding quality in the spot welding apparatus for welding workpieces.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the configuration of a laser welding system equipped with the laser spot welding apparatus of the present embodiment will be described with reference to FIG.
FIG. 1 is a configuration diagram of a laser welding system equipped with a laser spot welding apparatus according to an embodiment of the present invention.
Here, in the illustrated laser welding system A, the laser spot welding apparatus 10 attached to the robot arm 2a of the industrial robot 2 is made of a metal plate (plated steel plate) by an electromagnet 30 provided at the lower end of the laser spot apparatus 10. The workpieces W1 and W2 that are the objects to be welded on which the metal plates are stacked are held in close contact with each other, and the workpieces W1 and W2 that are held in close contact with each other are irradiated with a laser beam. Welding is performed.

Specifically, the laser welding system A includes a laser transmitter 1 that generates a laser beam, an industrial robot 2 that includes a robot arm 2a, and a laser spot welding apparatus 10 that is attached to the tip of the robot arm 2a. The optical fiber cable 40 for guiding the laser beam from the laser transmitter 1 to the laser spot welding device 10 and the control device 50 for controlling the driving of the laser transmitter 1 and the industrial robot 2 are provided.
Further, the laser transmitter 1 and the control device 50 are connected via a signal line S1 so that data can be exchanged between them. In addition, the industrial robot 2 and the control device 50 are connected via a signal line S2 so that data can be exchanged between them.
Note that, in the laser welding system A of the present embodiment, the laser transmitter 1 and the industrial robot 2 are realized by a well-known technique, and thus the following description is simplified.

  Specifically, the laser transmitter 1 follows the signal (laser output control signal) from the control device 50, and at the timing specified by the laser output control signal, the laser beam having the output specified by the laser output control signal. Is generated. The laser beam generated by the laser transmitter 1 is guided by the optical fiber cable 40 to the laser spot welding apparatus 10 attached to the tip of the robot arm 2a.

The industrial robot 2 is a general multi-axis robot, and the robot arm 2a is driven according to the teaching data set by the control device 50, so that the laser spot welding apparatus 10 is moved to various positions and directions in three dimensions. Move to.
The industrial robot 2 is configured to be able to control the drive of the laser spot welding device 10 attached to the tip of the robot arm 2a, and receives a signal (welding device control signal) transmitted from the control device 50, The laser spot welding apparatus 10 is operated in accordance with the welding apparatus control signal.

  Moreover, the control apparatus 50 is comprised by the computer provided with CPU and memory, for example, and the program for controlling the drive of the laser transmitter 1 and the industrial robot 2 is stored in the said memory. And drive control of the laser transmitter 1 and the industrial robot 2 is implement | achieved when the said CPU runs the program stored in the said memory.

The laser spot welding apparatus 10 includes a laser head 11 having one end attached to the tip of the robot arm 2 a and an electromagnet 30 attached to the outer peripheral surface of the lower end of the laser head 11.
The laser head 11 has an optical fiber cable 40 connected to the laser transmitter 1 connected to the upper end thereof. As a result, the laser beam generated by the laser transmitter 1 is guided to the laser head 11 by the optical fiber cable 40.
The laser head 11 irradiates the workpieces W1 and W2 with the laser beam guided by the optical fiber cable 40.
Further, the laser head 11 is equipped with a control circuit (not shown) that exchanges signals with the robot 2, and the operation of the entire laser spot welding apparatus 10 is controlled by this control circuit (not shown). The

  In the laser spot welding apparatus 10, the control circuit receives an instruction (welding apparatus control signal) from the control apparatus 50 via the robot 2, and supplies current to the electromagnet 30 in accordance with the received welding apparatus control signal. The workpieces W1 and W2 are held in close contact with the electromagnet 30. Then, a laser beam is irradiated from the lower end of the laser head 11 to the workpieces W1 and W2 that are adhered and held, and the workpieces W1 and W2 are welded.

As described above, in this embodiment, the lower end of the laser head 11 with respect to the workpieces W1 and W2 held in close contact by the magnetic attractive force of the electromagnet 30 (that is, in a state where the welded surfaces of the workpiece W1 and the workpiece W2 are in close contact). The laser beam is irradiated from the above.
That is, according to the present embodiment, when performing laser welding, the welding surfaces of the workpieces W1 and W2 are in close contact with each other due to the magnetic attractive force of the electromagnet 30, so that the workpieces W1 and W2 are welded during welding. It is possible to suppress boiling and explosion occurring on the welding surface of the steel, and as a result, it is possible to stabilize the welding quality.

Next, the configuration of the laser spot welding apparatus 10 according to the present embodiment will be described with reference to FIGS. 2 and 3.
FIG. 2 is a schematic diagram showing the configuration of the laser spot welding apparatus according to the embodiment of the present invention. FIG. 3 is a schematic view showing the bottom surface of the laser spot welding apparatus according to the embodiment of the present invention.

As shown in FIGS. 2 and 3, the laser spot welding apparatus 10 includes a laser head 11 and an electromagnet 30 attached to the outer peripheral surface of the lower end of the laser head 11.
Here, as shown in FIG. 2, the laser head 11 includes a main body portion 12 formed in a hollow cylindrical shape having a lower end portion opened, and a translucent lid body 20 that closes the opening of the lower end portion. It has.
Moreover, the end of the optical fiber cable 40 that guides the laser beam output from the laser transmitter 1 (see FIG. 1) is attached to the upper end of the main body 12. Further, a focusing optical system means for focusing the laser beam LA1 from the optical fiber cable 40 into the cylinder of the main body 12 and irradiating the focused laser beam LA2 toward the workpieces W1 and W2 through the lid body 20. 25 (for example, a lens) is provided.
In addition, although not shown in figure, the control circuit mentioned above is mounted in the main-body part 12. FIG.
The main body 12 is made of, for example, a lightweight reinforcing material (aluminum / titanium alloy or the like).

As shown in FIGS. 2 and 3, the electromagnet 30 is formed in a substantially cylindrical shape, and a through-hole (shaped so that the outer peripheral surface of the main body portion 12 of the laser head 11 is fitted to the shaft core portion). A through-hole penetrating the upper and lower surfaces is provided. And the electromagnet 30 is attached to the main-body part 12 by the lower end part of the main-body part 12 being inserted and fitted in the said through-hole.
The electromagnet 30 can be a superconducting magnet, for example.
Moreover, the shape of the electromagnet 30 described above is merely an example. The electromagnet 30 may have any shape as long as it can be attached to the lower end of the main body 12 of the laser head 11 (for example, a prismatic shape).

The focusing optical system means 25 of the present embodiment can be realized by a well-known technique, and the specific configuration is not particularly limited.
The focusing optical system means 25 may have any configuration as long as it can focus the laser beam from the optical fiber cable 40 and irradiate the focused laser beam onto the workpieces W1 and W2 (for example, a plurality of lenses, It may be constituted by a reflection mirror or the like).
Further, for example, a shutter for opening and closing the optical path of the laser beam is provided in the cylinder of the main body portion 12 of the laser head 11 so that the opening and closing operation of the shutter is controlled according to an instruction from the control circuit (not shown). It may be made.

Moreover, the lid 20 having the above-described translucency has predetermined heat resistance and predetermined pressure resistance (for example, made of tempered glass or the like). Moreover, it is preferable that the front-end | tip part 20a is formed in the circular arc convex shape (it is formed in R surface shape).
With this configuration, the lid 20 can directly hold the welded portion of the workpieces W1 and W2 irradiated with the laser beam, and thus effectively prevents an explosion occurring on the welded surface of the workpieces W1 and W2. be able to.

Next, operation | movement of the laser welding system A of this embodiment is demonstrated.
Specifically, first, the control device 50 drives the industrial robot 2 to move the laser spot welding device 10 attached to the tip of the robot arm 2a to the welding position of the workpieces W1 and W2.
Next, the control device 50 controls the laser spot welding device 10 via the industrial robot 2, passes a current through the electromagnet 30 of the laser spot welding device 10, and works W <b> 1 and W <b> 2 by the magnetic attraction force of the electromagnet 30. Keep the welded surface in close contact.
Thereby, the welding surfaces of the workpieces W1 and W2 were brought into close contact from one side of the workpieces W1 and W2 without providing a configuration for receiving the workpieces W1 and W2 on the side opposite to the lower end of the laser spot welding apparatus 10. Can be held in a state.

Next, the control device 50 controls the laser transmitter 1 to output a laser beam from the laser transmitter 1 in a state where the welding surfaces of the workpieces W1 and W2 are held in close contact with each other.
As a result, the laser beam from the laser transmitter 1 is guided to the laser head 11 by the optical fiber cable 40, and the workpieces W 1 and W 2 are irradiated with the laser beam from the lid 20 at the tip of the main body 12 of the laser head 11. The That is, a laser beam is irradiated to the welding part in a state where the welding parts of the workpieces W1 and W2 are in close contact with each other, whereby the workpieces W1 and W2 are welded.

As described above, according to the present embodiment, when the workpieces W1 and W2 on which the metal plates are stacked are welded, the welding surfaces of the workpieces W1 and W2 are brought into close contact with each other by the magnetic attractive force of the electromagnet 30. The workpieces W1 and W2 can be irradiated with a laser beam with the welded surfaces of W2 being in close contact with each other.
Therefore, according to this embodiment, boiling and explosion of the welding surfaces of the workpieces W1 and W2 can be prevented during welding, and welding quality can be stabilized.

Further, since the laser beam can be prevented from leaking by irradiating the laser beam with the workpieces W1 and W2 being in close contact with each other, it is necessary to use a shielding gas as in the above-described conventional laser welding apparatus. The equipment cost is reduced.
Further, in the present embodiment, unlike the one-side spot welding apparatus shown in FIG. 4 described above, it is not necessary to align the welding electrode 110 and the receiving electrode 150, so that the labor of the welding operation is reduced. Further, when the laser spot welding apparatus 10 of the present embodiment is mounted on the industrial robot 2, the robot teaching can be simplified because the welding position of the workpieces W1 and W2 can be accessed from one side.
In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible within the range of the summary.

In the above embodiment, the laser spot welding apparatus 10 performs welding in a state where the workpieces W1 and W2 are in close contact with each other and held, but the present invention is not particularly limited thereto.
The present invention can also be applied to welding other than the laser spot welding apparatus 10.
For example, the effect similar to that of the present embodiment can be obtained even when TIG welding (or CO2 welding) is performed after the workpieces W1 and W2 are brought into close contact with each other by an electromagnet.

  Further, for example, in the above-described embodiment, the laser spot welding apparatus 10 is mounted on the industrial robot 2, but is not particularly limited thereto.

It is a lineblock diagram of a laser welding system carrying a laser spot welding device of an embodiment of the present invention. It is the schematic diagram which showed the structure of the laser spot welding apparatus of embodiment of this invention. It is the schematic diagram which showed the bottom face of the laser spot welding apparatus of embodiment of this invention. It is a schematic block diagram of the one-side resistance spot welding system by a prior art. It is the schematic diagram which showed the laser welding apparatus by a prior art.

Explanation of symbols

A Laser welding system S1, S2 Signal line W1, W2 Work 1 Laser transmitter 2 Industrial robot 2a Robot arm 10 Laser spot welding device 11 Laser head 12 Main body 20 Lid body 25 Focusing optical system means 30 Electromagnet 40 Optical fiber cable 50 Control apparatus

Claims (2)

A spot welding apparatus that focuses a laser beam output from a laser transmitter and irradiates an object to be welded with a metal plate,
A main body portion formed in a hollow cylindrical shape having a lower end opened, and an optical fiber for guiding a laser beam output from the laser transmitter attached to the upper end portion;
A light-transmitting lid that closes the opening at the lower end of the main body;
A focusing optical system means provided in the cylinder of the main body, for focusing the laser beam from the optical fiber, and irradiating the focused laser beam toward the workpiece through the lid;
A spot welding apparatus comprising: an electromagnet having a predetermined magnetic force attached to an outer peripheral portion on a lower end side of the main body portion.   The spot welding apparatus according to claim 1, wherein the electromagnet is a superconducting magnet.

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