JPH0353812Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a resistance welding device, and more specifically,
A transformer is attached to the tip of the robot arm, and a welded part is arranged in a direction substantially perpendicular to the extending direction of the robot arm via a bracket, thereby reducing the time required for positioning the welded part with respect to the workpiece. The present invention relates to a resistance welding device that can improve positioning accuracy.

Resistance welding equipment applies electric current directly to the metal being welded.
The metals are melted and joined using Joule heat generated by the electrical resistance of the contact and the electrical resistance of the metal itself. In this case, the resistance welding device is equipped with a pair of arm tips that are facing each other with electrode chips to which a large current is applied, and by rotating one of the electrode arms, the metal to be welded is placed between them. Workpieces are placed in a stacked state and a large current is applied to perform the welding process.

By the way, when joining workpieces together using a resistance welding device, it is necessary to press the electrode tip perpendicularly to the welding surface of the workpieces in order to obtain an optimal joining condition. However, the electrode tip of the resistance welding device does not always face the welding surface of the workpiece perpendicularly due to the type of workpiece or the position in which it is introduced.

Therefore, a method has been adopted in which the position of the electrode tip is adjusted in accordance with the welding surface of the workpiece. That is, in such a resistance welding device, the welding part including the electrode tip is arranged at the tip of the robot arm, and the electrode tip is configured to be able to move arbitrarily with respect to the welding surface of the workpiece. There is. In this case, a transformer that generates a large current to energize the electrode chip is attached to the tip of the robot arm, and the welded part is attached via the transformer in the extending direction of the robot arm. is common.

However, in the resistance welding device configured as described above, the distance from the base end of the robot arm to the tip of the electrode tip is quite long, and a considerable amount of weight is concentrated near the tip, so the welding part Also, the center of gravity of the robot arm including the transformer will be closer to the tip. Therefore, when positioning the electrode tip with respect to the welding surface of the workpiece by moving the robot arm, the robot arm bends due to the weight of the welding part, etc., making it impossible to perform accurate positioning. There will be an inconvenience when it disappears. Furthermore, since the center of gravity is located near the tip of the robot arm, the moment of inertia during movement of the robot arm is large, and therefore it takes a long time for the movement of the electrode tip to completely stop and positioning to be completed. The drawback is that it takes time.

The present invention has been made to overcome the above-mentioned disadvantages, and includes installing a transformer for generating a large current at the tip of the robot arm, and
By attaching the welded part having the electrode chip via a bracket in a direction substantially perpendicular to the extending direction of the robot arm, the accuracy of positioning the electrode chip with respect to the workpiece is improved, and the time required for the positioning is shortened. The purpose of the present invention is to provide a resistance welding device that enables the following.

In order to achieve the above object, the present invention provides a resistance welding device that performs welding by applying a large current to a welding part provided at the tip of a robot arm, in which a bracket is attached to the tip of the robot arm, and the A transformer and a welding part are disposed on the bracket along a direction substantially perpendicular to the rotational axis of the tip of the robot arm, and the center of gravity of the transformer and the center of gravity of the welding part are aligned with the rotational axis. It is characterized in that it is eccentric on both sides in the substantially perpendicular direction.

Next, preferred embodiments of the resistance welding apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

1 to 3, reference numeral 10 indicates the main body of the resistance welding apparatus according to the present invention. This main body part 10 has first and second welded parts 12a, 12
b, and is attached via a joint part 16 to the distal end of a robot arm 14 which is displaceable in the directions of arrows X, Y, and Z. Note that the joint portion 16 rotates the main body portion 10 in the direction of arrow U via a rotation shaft 18 (see FIG. 2).

Therefore, as shown in FIG. 4, a cap member 19 is integrally engaged with the rotating shaft 18 of the joint portion 16, and a flange member 21 is attached to the cap member 19 with bolts 23. Ru. Further, this flange member 21 has brackets 20a, 20
b is attached by a bolt 27 via a connecting portion 25 formed at its lower end. In this case, the brackets 20a and 20b are integrally connected at their lower ends by the connecting portion 25, and extend in opposing directions substantially perpendicular to the direction in which the robot arm 14 extends. First and second welded portions 12a and 12b are provided between the upper ends of these brackets 20a and 20b. On the other hand, transformers 29a and 29b, which generate large currents and supply them to the first and second welded parts 12a and 12b, are attached to the lower end connecting portions 25 of the brackets 20a and 20b by bolts 31, respectively. .

The first welding section 12a has an upper electrode arm 22a and a lower electrode arm 24a, and opposing electrode tips 26a and 28a are attached to the tips of the upper electrode arm 22a and the lower electrode arm 24a, respectively. Similarly, the second welding part 1
2b has an upper electrode arm 22b and a lower electrode arm 24b, and mutually opposing electrode tips 26b and 28b are also attached to the tips of these arms, respectively.

A support shaft 3 is placed between the upper ends of the brackets 20a and 20b.
0 is pivotally supported, and one end portion of each of upper arm holders 32a and 32b that holds the rear end portions of the upper electrode arms 22a and 22b is pivotally attached to this support shaft 30, respectively. Note that each of the upper arm holders 32a, 3
At the other end of 2b is an arm opening/closing cylinder 34a,
34b are attached respectively. Further, the support shaft 30 has a lower arm holder 36 formed in a substantially L shape.
The upper ends of the lower electrode arms 24a and 36b are pivoted, respectively, and the rear ends of the lower electrode arms 24a and 24b are fixedly held at the bent intermediate portions of the lower arm holders 36a and 36b. Lower arm holders 36a, 36b
One end of each is pivotally attached to the lower end of the connecting member 42a, 42b via support shafts 40a, 40b. In this case, the cylinder rod 46a of the arm opening/closing cylinder 34a, 34b is connected to the other end of each of the connecting members 42a, 42b via a support shaft 44a, 44b.
46b are each pivoted.

The support shaft 30 further includes swing plates 48a and 48b.
The upper end of the is pivoted. These rocking plates 48a, 4
Stopper members 50a, 50b formed in a substantially U-shape are attached to the upper end portions of the upper electrode arms 8b, and the rear lower surface portions of the respective upper electrode arms 22a, 22b are attached to the upper surface portions 52a, 52b of the stopper members 50a, 50b. comes into contact. In addition, stopper members 50a, 50b
The rear upper surface portions of the respective lower electrode arms 24a, 24b abut against the lower surface portions 54a, 54b. A stopper pin 56 is provided between the swing plates 48a and 48b.
a, 56b are implanted. Here, each stopper pin 56a, 56b is connected to the upper arm holder 32a, 3
Convex portions 58a and 58b formed at the intermediate portion of 2b
and concave portions 60a, 60b formed at the bent portions of the lower arm holders 36a, 36b. On the other hand, an arm deflection cylinder 64 is connected via a support shaft 62 between the rear ends of the brackets 20a and 20b.
The cylinder rod 66 of the arm deflection cylinder 64 is pivoted to a support shaft 68 pivotally supported between the lower ends of the swing plates 48a and 48b.

The positive electrodes 72a, 7 of the transformers 29a, 29b are attached to the lower ends of the brackets 20a, 20b.
2b and the negative electrodes 74a, 74b are provided with an insulating plate 7.
6 through electrode plates 78a, 78b and 80a,
Each one end of 80b is connected. The other ends of the electrode plates 78a and 78b are connected to flexible conductive wires 82.
upper electrode arms 22a, 22 via a, 82b
b to each rear end. Similarly, the other ends of the electrode plates 80a, 80b are connected to flexible conductive wires 84a,
The lower electrode arms 24a and 24b are connected to each other via 84b.

The resistance welding device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the robot arm 14 is moved in the directions of arrows X, Y, and Z under the action of a drive source (not shown), and the main body 10 of the resistance welding apparatus is brought close to the welding locations of the works W ₁ and W ₂ . In this case, it is assumed that the workpieces W ₁ and W ₂ are set in advance at a predetermined position with the welding points overlapped.

Next, if the welding surfaces of the works W ₁ and W ₂ are inclined around the Y axis, the arm deflection cylinder 64 is driven to displace the cylinder rod 66 in the direction of arrow A (see FIG. 2). At this time, the swing plates 48a and 48b connected to the cylinder rod 66 are
It rotates in the direction of arrow B around 0. In this case, the stopper pins 56a, 56b implanted in the swing plates 48a, 48b move in the direction of arrow E about the support shaft 30 together with the swing plates 48a, 48b.
On the other hand, the upper electrode arms 22a, 22b are connected to the stopper members 50 fixed to the swing plates 48a, 48b.
It is pressed by the upper surface parts 52a and 52b of a and 50b, and rotates in the direction of arrow C about the support shaft 30. In this case, the upper electrode arms 22a, 22
Arm opening/closing cylinders 34a, 34b connected to the upper electrode arms 22a, 32b via upper arm holders 32a, 32b rotate in the direction of arrow D about the support shaft 30 together with the upper electrode arms 22a, 22b. Therefore, the lower electrode arms 24a and 24b fixed to the lower arm holders 36a and 36b are connected to the upper electrode arm 22.
a, 22b as well as the arm opening/closing cylinder 34
The cylinder rods 46a and 46b of the cylinders a and 34b and the connecting members 42a and 42b rotate about the support shaft 30 in the direction of arrow C. As a result, the welded portions 12a, 12b rotate in the direction of arrow C about the support shaft 30, resulting in the state shown in FIG. 3.

Here, when the welding surfaces of the works W ₁ and W ₂ are inclined around the X-axis, the main body portion 10 is rotated in the direction of arrow U by the rotating shaft 18 under the driving action of the joint portion 16 . As a result, the electrode chips 26a, 26b and 28 are attached to the tips of the upper electrode arms 22a, 22b and the lower electrode arms 24a, 24b.
a and 28b are positioned perpendicular to the welding surfaces of the workpieces W ₁ and W ₂ which are inclined around the X-axis and the Y-axis, respectively.

Next, in the state shown in FIG. 3, the arm opening/closing cylinders 34a, 34b are driven to displace the cylinder rods 46a, 46b in the direction of arrow F. At this time, the lower arm holders 36a, 36b connected to the distal ends of the cylinder rods 46a, 46b via the connecting members 42a, 42b rotate in the direction of arrow G about the support shaft 30. As a result, the lower electrode arms 24a, 24b, whose rear ends are fixed to the lower arm holders 36a, 36b, are separated from the lower surfaces 54a, 54b of the stopper members 50a, 50b, and together with the lower arm holders 36a, 36b, they are pivoted. It rotates about 30 in the direction of arrow H. Note that when the cylinder rods 46a, 46b are displaced by a predetermined amount in the direction of arrow F, the lower arm holder 36
The concave portions 60a, 60b of a, 36b are the rocking plate 48
Stopper pins 56a, 56 implanted in a, 48b
b. Therefore, the rotational movement of the lower electrode arms 24a, 24b in the direction of arrow H is prevented by the stopper pins 56a, 56b.

Further move the cylinder rods 46a and 46b to arrow F.
When displaced in the direction, the stopper pins 56a, 56
Under the action of arm opening/closing cylinders 34a, 34
b moves toward the lower arm holders 36a, 36b. That is, the arm opening/closing cylinder 34
a and 34b rotate in the direction of arrow I together with the upper arm holders 32a and 32b about the support shaft 30. As a result, the upper arm holders 32a, 3
Upper electrode arm 22 whose rear end is fixed to 2b
a, 22b are separated from the upper surface portions 52a, 52b of the stopper members 50a, 50b, and rotate in the direction of arrow J about the support shaft 30 together with the upper arm holders 32a, 32b. Then, when the cylinder rods 46a, 46b are further displaced in the direction of arrow F, the convex portions 58a, 58b formed on the upper arm holders 32a, 32b move from the rocking plate 48a,
Stopper pins 56a, 56b implanted in 48b
It will come into contact with. Therefore, the rotational movement of the upper electrode arms 22a, 22b in the direction of arrow J is prevented by the stopper pins 56a, 56b.

As described above, each welded portion 12a, 12b
between the electrode tips 26a, 28a and 26
b and 28b are in an open state. Next, by moving the robot arm 14, the welded portions of the works W ₁ and W ₂ are positioned between the electrode chips 26a and 28a and between 26b and 28b.

In this case, the welded parts 12a and 12b attached to the tip of the robot arm 14 are attached to the bracket 20.
a, 20b in a direction substantially perpendicular to the extending direction of the robot arm 14, that is, in the Z direction. Therefore, the center of gravity of the main body 10 is located near the tip of the robot arm 14. For example, the welded portion 12 which is a heavy member
The center of gravity is closer to the base end of the robot arm 14 than in the case where the robot arms 12a and 12b are arranged on the extension of the robot arm 14 via the transformers 29a and 29b. As a result, the amount of deflection of the robot arm due to the weight of the welded parts 12a, 12b, transformers 29a, 29b, etc. is suppressed to a minimum, so that the workpiece
Electrode chips 26a, 26b, 2 for W ₁ and W ₂
8a and 28b can be easily and accurately positioned.

Furthermore, the center of gravity of the main body 10 is the robot arm 14.
The moment of inertia is small because the robot arm 14 is closer to the base end of the work W ₁ ,
When moving toward W ₂ , the electrode tip 26a,
When 26b reaches a predetermined welding location, its movement can be stopped immediately. As a result, high-speed positioning becomes possible.

Next, the arm opening/closing cylinder 34a,
By driving 34b, the cylinder rod 46
a, 46b are displaced in a direction opposite to the direction of arrow F. In this case, lower arm holders 36a, 36b
The lower electrode arms 24a, 24b rotate around the support shaft 30 via connecting members 42a, 42b connected to the cylinder rods 46a, 46b.
The rear end side upper surface portion comes into contact with the lower surface portions 54a, 54b of the stopper members 50a, 50b, and the rotational movement thereof is stopped. Next, upper arm holders 32a, 3
2b rotates around the support shaft 30, and the rear end lower surface portions of the upper electrode arms 22a, 22b abut against the upper surface portions 52a, 52b of the stopper members 50a, 50b, thereby stopping the rotational movement. As a result, the welding surfaces of the workpieces W ₁ and W ₂ are sandwiched between the electrode tips 26a and 28a and between 26b and 28b attached to the tips of the upper electrode arms 22a and 22b and the lower electrode arms 24a and 24b. becomes.
When a welding current is supplied from this state through the transformers 29a, 29b, this current flows through the electrode chips 26a, 26a, 29b through the electrode plates 78a, 78b, 80a, 80b and the flexible conducting wires 82a, 82b, 84a, 84b. Between 28a and 26b, 28
Electricity is applied between b and welding of the workpieces W ₁ and W ₂ is performed.

The welding parts 12a and 12b are configured to be driven by independent arm opening/closing cylinders 34a, 34b and transformers 29a, 29b, respectively. Therefore, it is possible to set the welding angle of the welding part 12a and the welding angle of the welding part 12b independently.

As described above, according to the present invention, a transformer that generates a large current is attached to the tip of the robot arm, and a welded part is arranged in the tip in a direction substantially perpendicular to the direction of extension of the robot arm. are doing. Therefore, the center of gravity including the transformer and the welding portion is located closer to the base end of the robot arm. Therefore, the amount of deflection of the robot arm due to the weight of the transformer, welding section, etc. is suppressed to a minimum, and positioning of the welding section relative to the workpiece becomes easy and extremely accurate. In addition, since the moment of inertia of the robot arm is small, the time required from the start of movement of the robot arm until the welding part completely stops at a predetermined location on the workpiece is short.
It becomes possible to position the welded part in a short time.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design are possible without departing from the gist of the present invention. Of course.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the main body of the resistance welding device according to the present invention, FIG. 2 is a partially omitted side explanatory view of the main body of the resistance welding device according to the present invention, and FIG. 3 is the resistance welding device according to the present invention. FIG. 4 is a partially omitted side explanatory view showing a state in which the electrode arm of the main body of the welding device is tilted, and FIG. 4 is an exploded perspective view showing a support mechanism for the main body of the resistance welding device according to the present invention. 10... Main body part, 12a, 12b... Welding part,
14... Robot arm, 16... Joint part, 18
...Rotation axis, 20a, 20b...Bracket, 2
2a, 22b...upper electrode arm, 24a, 24
b...Lower electrode arm, 26a, 26b, 28
a, 28b... Electrode chip, 29a, 29b...
Transformer, 30... Support shaft, 34a, 34b... Arm opening/closing cylinder, 36a, 36b... Lower arm holder, 48a, 48b... Rocking plate, 50
a, 50b... Stopper member, 56a, 56b...
...Stopper pin, 58a, 58b...Convex portion, 6
0a, 60b...Concave portion, 64...Arm deflection cylinder, 78a, 78b, 80a, 80b...
Electrode plates, 82a, 82b, 84a, 84b...flexible conducting wires.

Claims (1)

[Scope of utility model registration request] In a resistance welding device that performs welding by applying a large current to a welding part provided at the tip of a robot arm, a bracket is attached to the tip of the robot arm, and the bracket has a rotating shaft attached to the tip of the robot arm. A transformer and a welding part are disposed along a direction substantially perpendicular to the center, and a center of gravity of the transformer and a center of gravity of the welding part are eccentric to both sides of the rotational axis in the direction substantially perpendicular to the rotational axis. A resistance welding device characterized by: