JPH08300160A - Spot welding equipment - Google Patents

Abstract

PURPOSE: To shorten contact time in a welding process by supporting an electrode plate provided with a projecting part that can engage with the inner circumference of the groove of a work with a floating support means and interposing the plate between the work and a welding tip. CONSTITUTION: An electrode plate 3 constituted of an electrically conductive member is supported to be displaceable with a floating support means. The projecting part 3A of the electrode plate 3 is engaged with the groove 92 of a work 90, 91. A welding tip 5 is driven in the direction approaching a welding tip 6, and the electrode plate 3 is interposed, thereby energizing and welding the work 90, 91 while they are pressed to each other. Then, the holding of the welding tips 5, 6 is released, thereby displacing the electrode plate 3 upward. Since the electrode plate 3 is interposed, the welding tip 5 may have a regular shape. In the case of positioning the welding tip 5, an accurate positioning for avoiding to come into contact with the side of the groove 92 is unnecessitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a spot welding apparatus for performing spot welding by superposing work pieces of plate-like members in a groove shape.

[0002]

2. Description of the Related Art In a vehicle such as an automobile, a body is composed of a plurality of outer plates joined by spot welding. Such a joint between the outer plates and the outer plate has hitherto been an end portion of the outer plate or the like. There is a method in which the step portions formed in the above are overlapped with each other to form a groove shape, and spot welding is performed in the groove portions to join them.

Such spot welding is employed, for example, for joining a roof panel of a vehicle body and a body side panel (for example, a rear fender). As shown in FIG. 7, the roof panel 90 and the body side 91 are joined together. The step portions 90A and 91A respectively provided at the end portions are overlapped with each other to form a groove portion 92 having a substantially rectangular cross section (cross section of the groove portion) opened toward the outside of the vehicle body.

The inner and outer peripheries (outer and inner sides of the vehicle body) of the bottom 92A of the groove 92 are as shown in FIG.
Welding is performed by sandwiching, pressing, and energizing the welding tips 5 ′ and 6 of the gun unit 2 supported by the robot hand 1.

Since the groove portion 92 has a recess opening toward the outside of the body, the width W of the inner periphery of the groove portion 92 in FIG. 7 is set to be narrow, for example, 6 mm to ensure the aesthetic appearance of the vehicle body and brazing. The post-treatment process can be omitted.

The welding tip in such spot welding is a special welding tip 5 having a plate-shaped tip as shown in FIG. 9 in order to avoid contact with the inner peripheral side surface of the groove 92 other than the welding position. 'Used.

The welding tip 5'has a base end supported by the gun unit 2 formed of a columnar member 50, and a plate-like portion 51 having a rectangular cross section from the lower end of the columnar member 50.
The plate thickness D of the plate-shaped portion 51 is set to a value smaller than the width W of the inner circumference of the groove portion 92, for example, 4 mm, and the bottom portion 92A of the groove portion 92 is pressed and sandwiched by the rectangular end surface 52. Since the side surface 53 does not contact the inner circumference of the groove portion 92,
Spot welding of the bottom portion 92A can be smoothly performed.

[0008]

However, since the welding tip 5'as described above has a thin plate-shaped tip, the welding position is limited, and it may not be applicable to general spot welding. Not only is the versatility of the gun unit 2 reduced and the operating rate of the welding robot is reduced, but the welding tip 5'having a plate-shaped tip does not smoothly cool the thin tip. In addition to the durability being lower than the conventional cylindrical welding tip having a hemispherical tip, the welding tip 5'is made of a material capable of securing a predetermined strength to withstand clamping and pressing. Since it is required, there is a problem that the welding tip 5'is more expensive than the conventional cylindrical welding tip.

Further, the width W of the groove 92 is determined by the roof panel 90.
Also, since it fluctuates depending on the dimensional error (tolerance) of the body side 91, it is necessary to drive the robot hand 1 so that the side surface 53 of the plate-shaped portion 51 does not contact the inner circumference of the groove portion 92 in FIG. It is possible to realize such a dimensional error of the work with high accuracy by an image recognition means or the like, but in such a case, not only the apparatus becomes complicated but also the takt time increases, which increases the manufacturing cost and This may cause a decrease in production efficiency.

Therefore, the present invention has been made in view of the above problems, and it is possible to perform spot welding in a narrow groove portion with high precision and speed using a conventional cylindrical welding tip having a hemispherical tip. It is an object of the present invention to provide a spot welding device capable of performing the above.

[0011]

According to a first aspect of the present invention, a work in which a plurality of plate-like members are respectively bent and formed and grooves are formed by superposing the plate-shaped members on each other, a gun unit is constituted, and the grooves of the work are opposed to each other. In a spot welding device including a pair of welding tips that can be brought into and out of contact with each other at a position, the groove portion is formed by a conductive plate-like member while being interposed between the work and the welding tip. Side, an electrode plate capable of coming into contact with and separating from the work, a convex portion projecting from the electrode plate toward the work and engageable with the inner circumference of the groove, and a direction in which the convex can be inserted into the groove of the work. And a floating support means for supporting the electrode plate so that the electrode plate can be relatively displaced.

In a second aspect based on the first aspect, the groove portion of the work has a substantially rectangular cross section, while the convex portion of the electrode plate has a substantially rectangular cross section engageable with the groove portion. .

According to a third aspect of the present invention, in the first aspect of the present invention, the groove portion of the workpiece has a substantially semicircular cross section, while the convex portion of the electrode plate has a substantially semicircular cross section capable of engaging with the groove portion. Equipped with.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the groove portion of the work has a substantially V-shaped cross section, while the convex portion of the electrode plate has a substantially triangular cross section engageable with the groove portion. Equipped with.

The fifth invention is the third or fourth invention.
In the invention described above, the gun unit includes a plurality of sets of welding tips, and the welding tips are arranged so as to be able to contact different positions of the electrode plate and the groove.

A sixth aspect of the invention is the first to fifth aspects of the invention.
In any one of the inventions described above, the floating support means supports the electrode plate so as to be relatively displaceable in a direction in which the electrode plate is brought into contact with and separated from the work, and also supports the electrode plate so as to be relatively displaceable in a direction along the surface of the work. A base, a means for driving the floating base toward the work, a balloon chuck that can be inserted from the floating base into a predetermined hole formed in the work, and a pressurized fluid is selectively supplied to the balloon chuck. A pressurized fluid supply means.

The sixth invention is the first to sixth inventions.
In any one of the inventions, the welding tip is
The end facing the work is formed into a substantially hemispherical shape.

[0018]

According to the first aspect of the invention, on the side where the groove of the work is opened, the electrode plate is supported by the floating support means at a position where the protrusion can be inserted into the inner circumference of the groove so as to be relatively displaceable with the work. Along with this, the electrode plate is interposed between the welding tip and the work, and when the gun unit is driven so that the welding tip holds and presses the work, the welding tip abuts the electrode plate on the side where the groove is opened. Drive the electrode plate toward the work, the electrode plate is displaced toward the work to engage the convex portion with the inner circumference of the groove portion, while the welding tip facing the outer circumference of the groove portion of the work abuts the groove portion. The groove is sandwiched and pressed by the pair of welding tips via the electrode plate. When the welding tip is energized, it is energized to the groove portion of the work through the convex portion of the electrode plate made of a conductive member, and is sandwiched between the convex portion of the electrode plate and the welding tip abutting the outer periphery of the groove portion. Spot welding is performed on the groove portion, and spot welding can be performed quickly without positioning the welding tip on the inner circumference of the groove portion.

According to the second aspect of the invention, since the groove of the work and the protrusion of the electrode plate are formed in a substantially rectangular cross section, the groove of the work presses the inner peripheral bottom at the top of the protrusion of the electrode plate, Spot welding is performed at this bottom.

Further, according to the third aspect of the invention, since the groove portion of the work and the convex portion of the electrode plate are each formed with a substantially semicircular cross section, the groove portion between the convex portion of the electrode plate and the welding tip facing each other with the workpiece sandwiched therebetween. Spot welding is performed on the circumference of.

According to the fourth aspect of the invention, since the groove of the work is formed in a substantially V shape and the projection of the electrode plate is formed in a substantially triangular cross section, the projection of the electrode plate and the welding tip facing the work are sandwiched. Spot welding is performed on the sides of the groove portion between.

According to a fifth aspect of the present invention, the welding tip is pressed against each side of the outer periphery of the V-shaped groove, while the protrusions of substantially triangular cross section are pressed against each side of the groove inner periphery. Since the groove of the V-shaped cross section is sandwiched by each side, spot welding can be performed at a plurality of points on the cross section of the groove to increase the welding point position to increase the welding strength. Even in the case of a semi-circle, by sandwiching it with multiple protrusions and multiple sets of welding tips at multiple positions on the circumference of the groove, it is possible to improve the strength by performing multiple spot welding on the cross section of the semi-circular groove. it can.

In the sixth aspect of the invention, the electrode plate is positioned by first displacing the floating base toward the work by the driving means to bring the electrode plate close to or in contact with the work. Along with the displacement of the floating base, the balloon chuck protruding from the floating base is inserted into the hole of the work. When the pressurized fluid is supplied to the balloon chuck by the pressurized fluid supply means, the balloon chuck is expanded and the floating base is driven in a direction along the surface of the work to a predetermined position with the hole of the work as a reference, and the floating base is moved to the predetermined position. The protrusion of the supported electrode plate is also positioned at a predetermined position where it can be inserted into the groove.

Further, in a seventh aspect, the welding tip is
The end facing the work is formed in a substantially hemispherical shape to form a general welding tip, and the hemispherical end is pressed against the outer periphery of the groove and the electrode plate of the plate-like member to perform welding.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 3 show an example in which the present invention is applied to a welding station of a vehicle.
Spot welding is performed in the groove portion 92 in which the ends of the roof panel 90 and the body side panel 91 of the vehicle body 9 conveyed by the above are bent and overlapped in the same manner as in the conventional example, and the spot welding is performed as shown in FIG. As shown in FIG. 5, the process is performed through the electrode plate 3 that is interposed between the work and the welding tip 5.

A floating unit 30 for supporting the electrode plate 3 and a welding robot (not shown) are arranged at a welding station where the vehicle body 9 is sequentially conveyed and positioned by the carriage 100.

1 and 2, the floating unit 30 includes a frame 31 supported by a structure (not shown), and an elevating base 33 that is driven relative to the frame 31 in the vertical direction (Z-axis direction) in the drawing. The floating base 34, which supports the electrode plate 3 at a position where it can face the work and is supported by the elevating base 33 and can be displaced in the horizontal direction, that is, the XY direction in the drawing, is positioned. Balloon chuck 4
It is composed mainly of. In the figure, the X-axis direction indicates the width direction of the vehicle body, the Y-axis direction indicates the front-back direction of the vehicle body, and the Z-axis direction indicates the vehicle body vertical direction.

The elevating base 33 formed of a plate-like member is connected to the lower ends of the guides 32 and 32 which are expandable / contractible in the Z-axis direction in the figure, and is also connected to the rod 7A of the air cylinder 7 standing on the frame 31. Then, the vehicle body 9 is driven in the vertical direction.

A plurality of brackets 33A projecting downward from the lower surface of the elevating base 33 and the elastic member 3 are provided.
Floating base 34 formed in a plate shape through 9
Are supported so as to be relatively displaceable in the horizontal direction.

At a predetermined position of the floating base 34, a columnar member 34A having a rectangular cross section is provided so as to project upward,
The side surfaces of the columnar member 34A are directed in the vehicle body length direction and the vehicle width direction, while the plurality of brackets 3 on the lifting base 33 side are provided.
3A is arranged so as to be able to face the side surfaces of these columnar members 34A, and the floating base 34 is predetermined to be displaced in the horizontal direction by an elastic member 39 interposed between each side surface of the columnar member 34A and the bracket 33A. Is acceptable within the range. The horizontal displacement is along the surface of the work, that is, along the surface of the vehicle body 9 near the joint between the roof panel 90 and the body side panel 91.

A groove portion 92 in which a roof panel 90, which is a predetermined welding position of the vehicle body 9, and a body saddle panel 91 are superposed on each other.
The electrode plate 3, which is interposed between the welding tip 5 and the groove 92, is supported on a predetermined lower surface of the floating base 34 which can face the movable base 34 so as to be vertically displaceable.

The electrode plate 3 is a floating base 3
4. A plurality of guide shafts 3 which penetrate 4 along the Z-axis direction
A flange (not shown) is formed on the upper end of the guide shaft 36, which is connected to the lower ends of the guide shafts 36 and 36, and an elastic member 37 is interposed between the upper end of the guide shaft 36 and the upper surface of the floating base 34. Then, the electrode plate 3 is supported so as to be relatively displaceable in the Z-axis direction with respect to the floating base 34, and is suspended.

The guide shaft 36 and the elastic member 37 are
A predetermined gap is formed between the electrode plate 3 descended to the most extended position of the air cylinder 7 and the work, and the electrode plate 3 is pressed against the elastic member 37 toward the vehicle body 9 from this position. It is set so that it can come into contact with the vehicle body 9, and the gap is set to, for example, 5 to 10 mm.

An elastic member 38 is attached to the guide shaft 36 between the floating base 34 and the electrode plate 3.
Is interposed and urges against the upward displacement of the electrode plate 3, and absorbs the machining accuracy of the vehicle body 9 in the Z-axis direction and the positioning error of the bogie 100.

The elastic members 37 and 38 are composed of coil springs and the like arranged coaxially with the guide shaft 36.

On the lower surface where the floating base 34 can face the through hole 96 of the parcel shelf 95 of the vehicle body 9,
The balloon chuck 4 is arranged at the lower end of the positioning shaft 35 protruding downward.

The balloon chuck 4 is formed of a substantially cylindrical bag-shaped member having elasticity, and is made of, for example, bag-shaped rubber or the like, and supplies pressurized air from a pressurized air supply means (not shown). As a result, the balloon chuck 4 is expanded and the outer diameter of the balloon chuck 4 is increased. On the other hand, when the pressurized air is released into the atmosphere, the balloon chuck 4 is contracted by its own elasticity.

When compressed air is supplied after the balloon chuck 95 is inserted into the through hole 96 in a contracted state,
The balloon chuck 4 expands to increase the outer diameter, presses the outer circumference of the balloon chuck 4 against the inner circumference of the through hole 96, and can position the positioning shaft 35 at the coaxial position of the through hole 96. 34
Is guided by the balloon chuck 4 and positioned at a predetermined position in the XY plane.

The parcel shelf 95 is a plate-like member that defines the interior of the vehicle body 9 and the trunk room.
Reference numeral 6 is a hole for forming a predetermined hole in the work, for example, a hole for mounting equipment such as a speaker (not shown).

Here, the electrode plate 3 supported by the floating unit 30 so as to be displaceable relative to the vehicle body 9 is composed of a plate-shaped conductive member, and as shown in FIG. Convex portion 3A that can be engaged with the circumference
Are projected from the lower surface of the electrode plate 3 toward the vehicle body 9. The electrode plate 3 may be made of a conductive material such as copper, or may be made of chrome copper CrCu, beryllium copper BeCu, or the like.

The top of the convex portion 3A is formed to have a predetermined height capable of contacting the bottom 92A of the groove 92, and in FIG. 3, it can contact at least the bottom 92A of the roof panel 90 facing the outside of the vehicle. With a high height.

Further, the convex portion 3A is formed along the groove portion 92 to have a predetermined length, for example, a length substantially equal to the entire length of the electrode plate 3 in the X-axis direction.

In this embodiment, the bent portions of the step portions 90A, 91A of the roof panel 90 and the body side panel 91 are formed to be bent with a predetermined curvature R, and the convex portion projected from the electrode plate 3 is shown. This step 90 is provided on the base end side of 3A.
The bent portion 3R is engageable with the curvature R of A and 91A.

Further, a cylindrical welding tip 5 having a hemispherical tip 5A is pressed against the upper surface of the electrode plate 3,
A pressing surface 3T that can be energized is formed, and the pressing surface 3T is configured by, for example, a plane parallel to the XY plane.

Here, the welding tip 5 is attached to the gun unit of the welding robot shown in FIG. 8 of the conventional example, and the welding tip 6 provided at a position facing the welding tip 5 is driven in the direction of approaching. By sandwiching the work,
Robot hand 1 that energizes and welds while pressing
Is configured to be freely displaceable in the welding station.

The operation of welding the roof panel 90 and the body side panel 91 by the spot welding apparatus configured as described above will be described below with reference to FIGS.

The air cylinder 7 is contracted and driven by pressurized air from a pressurized air source (not shown) to hold the floating unit 30 in the raised position, and the vehicle body 9 mounted on the carriage 100 is installed in the welding station. Position it in place.

Next, after the balloon chuck 4 is in a contracted state in which the balloon chuck 4 is opened to the atmosphere, the air cylinder 7 is driven to extend to the most extended position to lower the elevating base 33 and the floating base 34, and the balloon chuck 4 of the vehicle body 9 is moved. It is inserted into the through hole 96 formed in the parcel shelf 95.

At the most extended position of the air cylinder 7, a predetermined gap (for example, 5) is provided between the vehicle body 9 and the electrode plate 3.
10 mm) is formed.

When pressurized air is supplied from a pressurized air source (not shown) to inflate the balloon chuck 4, the substantially cylindrical balloon chuck 4 presses the outer circumference against the inner circumference of the through hole 96 to move the positioning shaft 35 to the X position. -Guide to the coaxial position of the through hole 96 on the Y plane.

That is, the balloon chuck 4 drives the floating base 34 in the horizontal direction via the positioning shaft 35 in order to absorb the positioning error of the carriage 100 in the horizontal direction and the error in the processing accuracy of the vehicle body. The base 34 is displaced relative to the elevating base 33 in the horizontal direction by deforming the elastic member 39 interposed between the elevating base 33 and the elevating base 33, and the convex portion 3A of the electrode plate 3 faces the groove portion 92 of the vehicle body 9. It can be positioned in any possible position.

On the other hand, the error in the vertical direction of the vehicle body, that is, the molding error of the vehicle body 9 or the positioning error of the carriage 100 is absorbed by the elastic members 37 and 38 interposed between the electrode plate 3 and the floating base 34. For example,
When the vehicle body 9 is displaced upward from a predetermined position over the gap between the electrode plate 3 and the vehicle body 9 due to a positioning error of the carriage 100, the electrode plate 3 comes into contact with the vehicle body 9 in the lowered position. , At this time, the elastic member 3
By contracting 8, the error in the vertical direction of the vehicle body can be absorbed.

The electrode plate 3 which has completed the horizontal positioning by the floating base 34 and the balloon chuck 4 which can be relatively displaced in the horizontal direction is positioned at a predetermined position where the convex portion 3A faces the groove portion 92 of the vehicle body 9.

Next, the robot hand 1 of the welding robot as shown in FIG. 8 is driven to displace the welding tips 5 and 6 of the gun unit 2 to a predetermined position facing the groove 92. The robot hand 1 is driven based on the preset teaching position.

The welding tip 5 disposed on the outside of the vehicle body 9 has a hemispherical tip 5A on the pressing surface 3A of the electrode plate 3, and the welding tip 6 disposed on the inside of the vehicle body 9 is the outer peripheral bottom of the groove 92. Face each other and drive the gun unit 2 so as to reduce the interval between the welding tips 5 and 6 to start clamping and pressing.

As shown in FIG. 3, the welding tip 6 on the inner side of the vehicle body 9 abuts against and presses the bottom portion 92A of the groove portion 92,
The welding tip 5 arranged outside the vehicle body 9 presses the electrode plate 3 toward the vehicle body 9.

The electrode plate 3 is the floating base 3
4 is displaced downward in the drawing against the elastic member 37 interposed between the convex portion 3A and the convex portion 3A, and the convex portion 3A is inserted into the groove portion 92.
While the bottom portion 92 is pressed by the top portion of A, the welding tip 6 facing the welding tip 5 pushes the bottom portion 92A of the groove portion 92 from the outer periphery, so that the roof panel 90 and the body side panel 91 are overlapped with each other. The end portions are suppressed from warping and can be firmly attached.

In this way, the roof panel 90 and the groove portion 92 of the body side 91 are formed by the projection 3A of the electrode plate 3 and the welding tip 6 which are interposed between the welding tip 5 and the groove portion 92.
Is clamped and pressed, and when the welding tips 5 and 6 are energized, the convex portion 3A to the bottom portion 9 of the electrode plate 3 mainly composed of copper are
An electric current flows to 2 and spot welding is performed.

When the nipping of the electrode plate 3 and the groove portion 92 by the welding tips 5 and 6 is released after the welding is completed, the electrode plate 3 is biased by the elastic member 37 interposed between the floating base 34 and displaced upward. , A predetermined gap is formed again with the vehicle body 9.

Then, the balloon chuck 4 is opened to the atmosphere and deflated, and then the air cylinder 7 is deflated and driven, whereby the electrode plate 3 is displaced to a predetermined raised position, and the balloon chuck 4 penetrates the through hole of the parcel shelf 95. After passing through 96, the vehicle body 9 placed on the carriage 100 is conveyed to the next step (not shown), and the vehicle body 9 to be welded next is passed.

Thus, the spot welding of the groove 92 is
Since it is designed to be sandwiched, pressed, and energized via the convex portion 3A of the electrode plate 3 that can be brought into and out of contact with the workpiece, the hemispherical tip 5
It is possible to employ a normal welding tip 5 formed in a columnar shape including A, and the special welding tip as in the above-mentioned conventional example is not required, so that the processing cost can be reduced.
The welding tips 5 and 6 may be positioned at positions where they are brought into contact with the pressing surface 3T of the electrode plate 3 and the outer periphery of the groove 92, respectively. Since it is not necessary to drive according to the forming error and positioning error of the work so as not to abut, it is possible to perform spot welding at an accurate position at all times while performing positioning work quickly based on the teaching position of the welding robot. Therefore, the takt time of the welding process can be shortened to improve the productivity, and the durability and versatility can be improved as compared with the special welding tip as in the conventional example, The operating rate of the welding robot can be improved.

Further, the electrode plate 3 is supported by the floating base 34 which can be displaced in the horizontal direction, and
Since the balloon chuck 4 that performs positioning by being inserted into the hole formed in the vehicle body 9 is provided, the balloon chuck 4 is inserted into the hole of the vehicle body 9 without detecting a molding error of the vehicle body 9 or a positioning error of the carriage 100. Since the electrode plate 3 can be positioned quickly and accurately just by inserting the compressed air after the insertion, the time required for the positioning can be greatly reduced and the productivity can be improved.

FIG. 4 shows a second embodiment, in which the groove portion of the work of the first embodiment is formed by a semicircular groove portion 92 ', and the convex portion of the electrode plate 3 is also a semicircular convex portion. Three
A'is the same as in the first embodiment except for the above.

Grooves 90A 'formed by bending the ends of the roof panel 90 and the body side panel 91 with a predetermined curvature,
As the groove 91A ', these groove portions 90A' and 91A 'are overlapped to form a groove portion 92', and the convex portion 3A 'of the electrode plate 3 is inserted into this groove portion 92' and pressed to perform spot welding.

In this case, if the apex (the lowermost end in the figure) of the protrusion 3A 'of the electrode plate 3 is within the width of the groove 92', the apex of the protrusion 3A 'is a semicircle when the electrode plate 3 is lowered. While driving the electrode plate 3 in the horizontal direction while being guided by the inner periphery of the groove 92 ', the apex of the convex portion 3A' is groove 92 '.
Can be brought into contact with the innermost bottom edge of the electrode plate 3
Can be positioned more roughly,
The takt time of the welding process can be shortened regardless of the forming error and the positioning error of the work.

FIG. 5 shows a third embodiment, in which the groove portion 92 of the first embodiment is constructed in a rectangular cross section, and the other construction is the same as that of the first embodiment.

In the first embodiment, the bent portions of the step portions 90A, 91A of the roof panel 90 and the body side panel 91 are bent and formed with a predetermined curvature R, while the step portion 90A,
91A is formed by bending at a substantially right angle, and the base end side of the convex portion 3A protruding from the electrode plate 3 is also formed at a substantially right angle in response to the substantially right-angled step portions 90A, 91A.

FIG. 6 shows a fourth embodiment in which the groove 92 of the first embodiment has a V-shaped groove 92 "in cross section, and two sets of welding tips 5A, 5B, 6A and 6B are used. The electrode plate 3 is provided with a convex portion 3A ″ that can be engaged with the V-shaped groove portion 92 ″ so as to be sandwiched and pressed, and a pressing surface 3Ta with which the welding tips 5A and 5B come into contact with and separate from each other.
3Tb is formed, and other structures are the same as those in the first embodiment.

A groove 90 is formed by bending the cross sections of the end portions of the roof panel 90 and the body side panel 91 into a V shape.
As A "and 91A", these groove portions 90A "and 91A"
To form a V-shaped groove portion 92 ", and the convex portion 3 having a triangular cross section that can be engaged with the groove portion 92".
A ″ is projected from the electrode plate 3.

The sides of the convex portion 3A "are 3AL and 3AR, respectively.
Then, the welding tips 5A and 6A are driven to expand and contract in the direction orthogonal to the side 3AR to clamp and press, while the welding tips 5B and 6B are driven to expand and contract in the direction orthogonal to the side 3AL to clamp and press. Then, 2 sets of welding tips 5A, 5
The axes B, 6A and 6B are inclined at a predetermined angle α with respect to the Z axis in the figure.

The pressing surfaces 3Ta and 3Tb with which the welding tips 5A and 5B come into contact with and separate from each other are formed as planes parallel to the sides 3AR and 3AL, and two sets of the welding tips 5A and 5A are provided.
The roof panel 90 and the body side panel 91 sandwiched and pressed by B, 6A, and 6B are the side 3AL of the convex portion 3A ″,
It is possible to improve the strength by spot welding by forming nuggets at two locations corresponding to 3AR.

If the apex 3AT (bottom end in the drawing) of the convex portion 3A "of the electrode plate 3 is within the width of the groove 92", the apex 3AT of the convex portion 3A "is lowered when the electrode plate 3 is lowered. While driving the electrode plate 3 in the horizontal direction guided by the inner circumference of the 92 ", the apex 3AT of the convex portion 3A"
Can be brought into contact with the innermost lower end of the groove portion 92 ″, and the apex 3AT of the convex portion 3A ″ can be positioned within the width of the groove portion 92 ″, so that the electrode plate 3 can be roughly positioned. Therefore, the takt time of the welding process can be shortened as in the second embodiment.

[0074]

As described above, according to the first aspect of the present invention, the groove portion of the work is made of the conductive member when the welding tip is energized by being sandwiched and pressed by the pair of welding tips through the electrode plate. Electric current is supplied to the groove portion of the work through the convex portion of the electrode plate, spot welding is performed in the groove portion between the convex portion of the electrode plate and the welding tip contacting the outer periphery of the groove portion,
Spot welding can be performed quickly without positioning the welding tip on the inner periphery of the groove, and the welding tip may be positioned at a position where it abuts the electrode plate and the outer periphery of the groove, respectively. Since it is not necessary to drive the welding tip on the inner circumference of the groove according to the molding error and positioning error of the work so as not to contact the side surface,
It is possible to perform spot welding at a precise position at all times while performing positioning work quickly based on the teaching position of the welding robot, which can shorten the takt time of the welding process and improve productivity. Further, it is possible to improve durability and versatility as compared with the special welding tip as in the conventional example, and it is possible to improve the operating rate of the welding robot and improve the productivity.

Further, in the second invention, since the groove of the work and the convex portion of the electrode plate are formed in a substantially rectangular cross section, the groove portion of the work is pressed at the bottom of the inner peripheral portion by the top of the convex portion of the electrode plate, Spot welding can be performed at this bottom.

According to the third aspect of the invention, since the groove of the work and the protrusion of the electrode plate are formed in a substantially semicircular cross section, the groove between the protrusion of the electrode plate and the welding tip facing each other with the work sandwiched therebetween. Spot welding can be performed on the circumference of.

According to the fourth aspect of the invention, since the groove portion of the work is formed in a substantially V shape and the convex portion of the electrode plate is formed in a substantially triangular cross section, the convex portion of the electrode plate and the welding tip facing the work piece are sandwiched. Spot welding can be performed on the sides of the groove between.

According to the fifth aspect of the invention, the welding tip is pressed against each side of the outer periphery of the V-shaped groove portion, while the protrusions of substantially triangular cross section are pressed against each side of the groove inner portion. Since the groove of the V-shaped cross section is sandwiched by each side, spot welding can be performed at a plurality of points on the cross section of the groove to increase the welding point position to increase the welding strength. Even in the case of a semi-circle, by sandwiching it with multiple protrusions and multiple sets of welding tips at multiple positions on the circumference of the groove, multiple spot welding can be performed on the cross section of the semi-circular groove to improve the welding strength. You can

Further, according to the sixth aspect of the invention, the positioning of the electrode plate can always be accurately performed with reference to the hole formed in the work, and this positioning can be achieved simply by expanding the balloon chuck inserted into the hole. Therefore, it is possible to easily and quickly absorb the forming error and the positioning error of the work even with the simple configuration, and it is possible to reduce the takt time of the welding process.

Further, in the seventh invention, the welding tip is
Since the end facing the work can be formed into a generally hemispherical shape to form a general welding tip, and there is no need for a special welding tip as in the conventional example, the cost of the welding process is reduced. Moreover, by adopting a general welding tip, the versatility of the welding robot can be secured and the operating rate can be improved.

[Brief description of drawings]

FIG. 1 is a schematic front view of a welding device of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is an enlarged cross-sectional view of part A of FIG.

FIG. 4 is a sectional view of a welding device showing a second embodiment.

FIG. 5 is a sectional view of a welding apparatus showing a third embodiment.

FIG. 6 is a sectional view of a welding device showing a fourth embodiment.

FIG. 7 is a perspective view showing a state of welding a conventional roof panel and a body side.

FIG. 8 is a sectional view of a roof panel and a body side at a welding position.

FIG. 9 shows a tapered welding tip, (A) is a plan view,
(B) shows a front view and (C) shows a side view.

[Explanation of symbols]

 1 Robot Hand 2 Gun Unit 3 Electrode Plate 3A Convex Part 3T Pressing Surface 4 Balloon Chuck 5, 6 Welding Tip 7 Air Cylinder 30 Floating Unit 31 Frame 32 Guide 33 Lifting Base 34 Floating Base 35 Positioning Shaft 36 Guide Shaft 37, 38 Spring 90 Roof panel 91 Body side panel 90A, 91A Step portion 92 Groove portion 92A Bottom portion 95 Parcel shelf 96 Through hole

Claims (7)

[Claims] 1. A work in which a plurality of plate-shaped members are formed in a bent shape and are overlapped with each other to form groove portions,
In a spot welding apparatus comprising a gun unit and a pair of welding tips capable of contacting and separating at a position facing the groove portion of the work, in addition to being interposed between the work and the welding tip, conductive An electrode plate formed of a plate-like member and capable of coming into contact with and separating from the work on the side where the groove is opened; a convex portion projecting from the electrode plate toward the work and engageable with the inner circumference of the groove; A spot welding device, comprising: a floating support means for supporting the electrode plate such that the projection is relatively displaceable in a direction in which the projection can be inserted into the groove of the work. 2. The spot according to claim 1, wherein the groove portion of the workpiece has a substantially rectangular cross section, while the convex portion of the electrode plate has a substantially rectangular cross section capable of engaging with the groove portion. Welding equipment. 3. The groove of the workpiece has a substantially semi-circular cross section, while the convex portion of the electrode plate has a substantially semi-circular cross section that can be engaged with the groove.
Spot welding equipment according to. 4. The groove of the workpiece has a substantially V-shaped cross section, while the convex portion of the electrode plate has a substantially triangular cross section capable of engaging with the groove.
Spot welding equipment according to. 5. The gun unit is provided with a plurality of sets of welding tips, and the welding tips are arranged so as to be able to come into contact with different positions of the electrode plate and the groove portion, respectively. Item 4. The spot welding apparatus according to item 4. 6. A floating base that supports the electrode plate such that the electrode plate is relatively displaceable in a direction in which the electrode plate is in contact with and away from the work, and that the electrode plate is relatively displaceable in a direction along a surface of the work. Means for driving the floating base toward the work, a balloon chuck insertable from the floating base into a predetermined hole formed in the work, and a pressurized fluid for selectively supplying a pressurized fluid to the balloon chuck The spot welding apparatus according to any one of claims 1 to 5, further comprising: a supply unit. 7. The spot welding apparatus according to claim 1, wherein the welding tip has a substantially hemispherical end portion facing the work.