JP2587273B2 - Welding equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a welding apparatus, and more particularly to a welding apparatus for performing direct welding and indirect welding to a body of an automobile with a stud gun.

(Prior art)

Conventionally, as a welding device that welds and joins a dash lower panel and other components to an underbody in a body assembly line that assembles the body of an automobile, a welding device that can perform direct welding and indirect welding, commonly called a tunnel robot, is used. Used.

In the above welding apparatus, a back bar having a plurality of back electrodes corresponding to the direct welding locations of the underbody is arranged below the underbody, and a ground electrode for indirect welding is arranged below the underbody. The parts corresponding to the back electrode are sequentially directly welded with the stud gun provided in the hand part of the welding robot from the upper part of the underbody in order, and the above-mentioned stud gun indirectly welds several places near the ground electrode. It has become. The indirect welding is used for a portion where the back electrode cannot be arranged because a member joined in advance exists under the underbody.

[Problems to be solved by the invention]

In the above welding apparatus, the stud gun is pressurized and driven by a gun actuator such as an air cylinder when the welding is energized. However, since each direct welding point is directly supported by the back electrode, a sufficient predetermined striking force (about 250 to 400 kg) is applied. )
Can press and drive the stud gun.

However, each indirect welding point is not directly supported by the ground electrode, and is designed to support the pressing force from the stud gun via the underbody member. When the stud gun is driven, there is a problem that the welding location is deformed into a concave shape.

An object of the present invention is to provide a welding apparatus that can prevent deformation of a work at an indirect welding point.

[Means for solving the problem]

The welding apparatus according to the present invention includes a welding gun unit having a stud gun and a gun actuator for driving the stud gun, and a back bar unit having a back electrode capable of supporting a work and directly welding the work together with the stud gun. In the welding device provided, the back bar unit is provided with an earth electrode capable of indirectly welding the work together with the stud gun, and the welding force of the stud gun in the welding gun unit is lower in the indirect welding than in the direct welding. A control means for controlling the gun actuator so as to be weakened is provided.

[Action]

In the welding apparatus according to the present invention, since the welding gun unit is provided with control means for controlling the gun actuator so that the striking force of the stud gun is weaker at the time of indirect welding than at the time of direct welding, the stud gun is provided during indirect welding. Therefore, even when the rigidity of the work to be welded is insufficient, the work does not deform into a concave shape.

〔The invention's effect〕

According to the welding device according to the present invention, by providing the control means having a simple structure to the welding gun unit as described above, the impact force of the stud gun is reduced during indirect welding compared to direct welding, thereby deforming the work. Can be prevented.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The present embodiment is an embodiment in which the present invention is applied to a welding apparatus generally called a tunnel robot for spot welding mainly an underbody of an automobile body.

As shown in FIGS. 1 and 2, the welding device W includes an electrode device 1 (which corresponds to a back bar unit) on which a body B being assembled is placed, and an articulated welding robot. And direct welding is sequentially applied to a plurality of locations of the underbody Bu.
Are sequentially subjected to indirect welding at a plurality of locations.

The electrode device 1 will be described. A plate-shaped base 3 driven by a lift mechanism (not shown) is provided.
A center back bar 4 is provided at the center of the base 3 so as to be fitted in the shaft tunnel 30 of the underbody Bu. The center back bar 5 has a plurality of back electrodes respectively corresponding to the direct welding joints 31 of the shaft tunnel 30. 4a, and a pair of left and right back bars 5 are also provided on the base 3 behind the center back bar 4.
Are also provided with a pair of back electrodes 5a.

The center back bar 4 and the back bar 5 are made of copper, and the center back bar 4 is supplied with cooling water from the outside as shown by arrows AB.

A pair of left and right copper back bars 6 are erected near the front of the center back bar 4, and a ground electrode 6 a for indirect welding is mounted on the top of the back bar 6. Has a low copper back bar 7
Is mounted on the base 3, and an earth electrode 7 a for indirect welding having an inclined upper end surface descending rearward is mounted on the top of the back bar 7.

On the left and right sides of the base 3, there are provided current path connecting mechanisms 8, respectively. On the left and right sides of the base 3, there are provided main current path connecting mechanisms 9, and through the air cylinder 10 of the main current path connecting mechanism 9. When the power supply rod 9a is connected to the power supply rod 9a and the power supply rod 11a is connected via the air cylinder 11 of the power supply path connection mechanism 8, the back electrodes 4a and 5a of the center back bar 4 and the back bar 5 are connected to the ground. When the power rod 12a is connected via the air cylinder 12 with the power rod connected, the ground electrode 6a of the back bar 6 is connected to the ground, and the air cylinder is connected with the power rod 9a.
When the energizing rod 13a is connected via the 13, the ground electrode 7a of the back bar 7 is connected to the ground.
The current path connecting mechanism 8 is provided for selectively connecting the center back bar 4, the back bar 5, the back bar 6, and the back bar 7 to the ground at the time of welding to prevent a shunt. In FIGS. 1 and 2, reference numeral 14 denotes a support for supporting the body B.

The welding robot 2 is a four-axis articulated robot and corresponds to a welding gun unit. An air cylinder 17 as a gun actuator is attached to a hand 16 at the tip of an arm 15. A stud gun 18 is attached to the tip of the piston rod, and the electrodes of the stud gun 18 are connected to a welding current / voltage control device (not shown).
, A predetermined welding current flows through the underbody Bu at the welding location toward the electrode device 1, that is, toward the ground.

The welding robot 2 itself is controlled by the robot controller so as to move the stud gun 18 in a predetermined order to a predetermined location to be welded based on the teaching information stored in the robot controller. Although it is configured as described above, since it is the same as an existing general one, a detailed description is omitted.

Here, the structure for performing indirect welding in the body B will be briefly described with reference to FIGS. 2 to 4.
A front frame rear 33R, which is a rear end portion of the pair of front frames 33, is disposed along the lower surface of the dash lower panel 35 as shown in FIGS. The dash lower panel 35 is joined to the upper surfaces of the joining flanges 33a and 33b. Fig. 3 shows body B
Although the front frame rear 33R on the left side is shown, the dash lower panel 35 is provided between the front frame rear 33R and the side panel to reinforce the connection structure between the front frame rear 33R, the dash lower panel 35, and the side panel (not shown). A torque box 36 is provided on the lower side, a vehicle width inside end of the torque box 36 is joined to a side of the front frame rear 33R, and an upper end of the torque box 36 is a gusset for reinforcing an upper end of the front frame rear 33R. 34 and a dash lower panel 35, and a vehicle width outside end of the torque box 36 is connected to a side panel. A torque box 36 is joined to the front frame rear 33R in advance, and a dash lower panel 35 forming a part of the under body Bu is mounted on the upper surface thereof. Join the frame rear 33R.

By the way, it is difficult to arrange the back electrode in the joint 37 of the joint flange 33a outside the front frame rear 33R because the torque box 36 exists below the joint, and therefore, as shown in FIG. Indirect welding is performed by the stud gun 18 in a state where the ground electrode 7a of the direct back bar 7 is in contact with the lower surface of the front frame rear 33R. The joint between the gusset 34 and the dash lower panel 35 is joined by indirect welding using the back bar 6, and the joint 38 of the joint flange 33b inside the front frame rear 33R is shown in FIG. It is joined by direct welding using a back bar that is not used.

In addition, as shown in FIG.
And is elastically urged toward the front frame rear 33R by a compression spring 7b.

By the way, in the welding apparatus W of the present application, the part to be indirectly welded is not directly supported by the earth electrodes 6a and 7a, and the stud gun 18 is formed by two or three plate members of the body B.
The impact force of the stud gun 18 is reduced to 250 when direct welding is performed.
The impact force control device 50 (FIG. 5) for setting the impact force of the stud gun 18 to a value smaller than the impact force at the time of direct welding, for example, 50 kg, while performing indirect welding while setting the impact force to, for example, 300 kg in a range of 400 kg. ) Is provided in the welding robot 2.

The striking force control device 50 will be described with reference to FIG. 5, for example, in the middle of an air passage connecting the air supply source 39 that supplies pressurized air of about 7 kg / cm ² to the working chamber 17a of the air cylinder 17, A high-pressure circuit in which an electromagnetic on-off valve 40 and a regulator 41 with a set pressure of 6 kg / cm ² are connected in series, and an electromagnetic on-off valve
The low pressure circuit formed by connecting the regulator 42 having a set pressure of 1 kg / cm ² in series is connected in parallel, and the solenoids of the solenoid valves 40 and 42 are controlled by the controller 44. That is, the controller 44 receives the switching signal from the robot controller, and opens and closes the on-off valve 40 and closes the on-off valve 42 when performing direct welding, and closes and opens the on-off valve 42 when performing indirect welding. Valves 40 and 42 are controlled as described above. The above air cylinder 17 is 300 kg with 6 kg / cm ² air
Is applied to the stud gun 18 and 50 kg of impact force is applied to the stud gun 18 with 1 kg / cm ² of air. The rod-side chamber 17b of the air cylinder 17 is open to the atmosphere. Since the impact force control device 50 is provided in the welding robot 2 as a welding gun unit, it may be connected to an air supply source 39 for supplying one type of normal pressurized air. The compressed air supply system is simplified.

As described above, since the striking force control device 50 is provided, the striking force of the stud gun 18 is set sufficiently large during direct welding to ensure welding quality, while the striking force of the stud gun 18 is set small during indirect welding. Thus, deformation of the body B can be prevented.

Note that, instead of the on-off valves 40 and 42, a 3-port 2-position switching valve or a 3-port 3-position switching valve (including the shut-off position) is used.
It may be configured to be selectively connected to one of the regulators 41 and 43. Further, it is conceivable to switch the air pressure in three or more steps so as to obtain a striking force corresponding to the rigidity of the member at the indirect welding point.

It is needless to say that the present invention can be similarly applied to a case where a hydraulic cylinder is used as a gun actuator.

In addition, it is needless to say that the present invention can be similarly applied to a welding device including various stud gun driving devices (stud gun units) other than the welding robot 2.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a perspective view of a welding apparatus, FIG. 2 is a perspective view showing a state where a body is set in the welding apparatus, and FIG. Perspective view of joint of dash lower panel, 4th
Fig. 3 is a sectional view taken along the line IV-IV in Fig. 3, and Fig. 5 is a configuration diagram of the striking force control device. 1 ... electrode device, 2 ... welding robot, 4,5,6,7
…… Back bar, 4a ・ 5a …… Back electrode, 6a ・ 7a …… Earth electrode, 17 …… Air cylinder, 18 …… Stud gun,
50 ... Blowing force control device.

Claims (1)

(57) [Claims] 1. A welding apparatus comprising: a welding gun unit having a stud gun and a gun actuator for driving the stud gun; and a back bar unit having a back electrode capable of supporting a work and directly welding the work together with the stud gun. In the apparatus, the back bar unit is provided with an earth electrode capable of indirectly welding the work together with the stud gun, and the welding gun unit is configured so that the impact force of the stud gun is weaker in indirect welding than in direct welding. A welding device, further comprising control means for controlling a gun actuator.