JP2000301346A - Mush-seam welding method and apparatus thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify clamp in a work feeding device and to obtain terrazzo blanks material by butting two pieces of metal plates with a narrow overlapping width, crushing the overlapped joining part together with a regular welding after tack-welding and executing a seam welding. SOLUTION: When two metal plates 1, 2 are supplied on a table in the work feeding device 11, the welding end surfaces of the metal plates 1, 2 are butted on a stopper 14 and set to the narrow overlapping width. Plural electrode tips in a spot welder 9 are inserted into the overlapped joining part and plural spot weldings are simultaneously executed to execute the tack-welding. When the tack-welding is completed, the work is carried to the following seam-welding process with the work feeding device 11. The overlapped joining part is pressurized with an electrode ring for seam welding to load the high pressure, and an indirect energizing is applied to an electric circuit formed with a back bar 8. In this way, while reducing the metallic plates 1, 2 to a prescribed plate thickness, a linear welding is executed in the whole length direction of the joining part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mash seam welding method and apparatus useful for manufacturing a so-called tailored blank material for joining metal plates used for materials such as side members for automobiles.

[0002]

2. Description of the Related Art In the mash seam welding method, two metal plates are butted together with a slight overlap margin, and the joint formed by the butting is sandwiched between a pair of electrode rings for seam welding from above and below. Supply the necessary pressure and welding current to the electrode wheel, rotate the electrode wheel simultaneously with the main welding, and crush it to a thickness equal to or close to the thickness of one base material, while crushing the joint along the entire length. This is a method of performing seam welding.

[0003]

In the mash seam welding method, the overlap margin is very narrow, about the plate thickness. Therefore, unless both plates are firmly fixed with a clamp device, the lap margin due to thermal expansion due to resistance heat during seam welding. The plate may escape from the electrode ring when it is deformed or extremely severe.

For this reason, in the conventional mash seam welding apparatus, it is necessary to uniformly clamp the entire length of the welding line of the plate to be welded with a large clamping force. When the clamp is low, the overlap between the welding start end and the welding end of the lap joint must be set in advance to reduce the change in the lap margin caused by the increase in the force due to thermal expansion as the welding progresses in the welding width direction. In some cases, the fee may be increased.

However, the conventional welding method of this type has the following problems. In order to obtain a strong clamping force, a high-rigidity clamp beam was required using a high-output hydraulic or air cylinder or electric motor. If the clamping force is increased, the device will be commensurate with that, the weight will increase, and the power to move the clamping device will be greatly increased. In addition, equipment costs will increase. In order to prevent deformation of the lap margin due to thermal expansion that increases as the welding progresses, a lap margin adjustment mechanism may be required in advance to widen the welding end of the lap margin. Also, in order to make the clamps even, a split clamp may be used in the main beam, which makes the equipment complicated and expensive.

[0006]

Therefore, the present invention takes the following technical means to solve the above-mentioned problems. That is, the invention according to claim 1 is to preliminarily tack-weld a lap joint portion formed by abutting two metal plates and providing a slight overlap margin; Seam welding is performed while crushing the lap joint part to a thickness equal to or close to at least one base metal plate thickness.

[0007] In the second aspect of the present invention, in the case of the tack welding, spot welding is performed by abutting the end face of the lap joint portion against a step formed on the electrode surface.

A third aspect of the present invention is to provide a lap joint formed by abutting two metal plates and providing a slight overlap margin, and tack-welding at an appropriate interval, and then attaching the joint to a back bar. And one of the twin-type seam welding electrode wheels, which is arranged opposite to the back bar, presses the lap joint portion,
The other electrode ring for seam welding presses the other mating plate of the lap joint part, and sets the welding type to indirect energization. A mash that performs one-dimensional welding in the full length direction of the joint while crushing to a plate thickness approaching it
It is a seam welding method.

A fourth aspect of the present invention is a spot welding machine for tack-welding a lap joint formed by abutting two metal plates with a slight overlap margin at appropriate intervals, and the spot welding machine. Then, the lap joint portion is supported by a back bar, and the lap joint portion supported by the back bar is pressurized by a seam welding electrode wheel, and at the same time as the main welding, the thickness is equal to or close to the thickness of one base material. A mash seam welder for performing one-dimensional welding in the entire length direction of the joint while crushing the back bar, wherein the back bar is shifted by a shift device in a direction perpendicular to the seam welding line direction, whereby the back bar is shifted. A mash seam welding apparatus characterized in that the amount of wear of the mash is reduced.

A fifth aspect of the present invention resides in a mash seam welding apparatus wherein a workpiece is moved between respective steps of the spot welding machine and the mash seam welding machine by a feeder. .

According to a sixth aspect of the present invention, in the mash seam welding machine, a seam welding electrode wheel is mounted on a robot hand in which a welding locus of a lap joint portion is stored in advance, and the mash seam welding machine is required for the mash seam welding. A mash seam welding apparatus characterized in that high pressure torque is generated by the robot and the electrode wheel is rotationally driven along a predetermined welding locus to perform seam welding.

According to a seventh aspect of the present invention, a twin seam head having two seam electrode wheels is mounted on the robot hand, and the robot hand generates a high pressurizing torque required for mash seam welding to thereby improve the internal force. A mash seam welding apparatus characterized by performing direct seam welding.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example in which tack welding is performed by spot welding in a state of securing a lap allowance e in which two metal plates 1 and 2 are stacked in the method of the present invention.
FIG. 2 shows a plan view of a lap welded portion of a temporarily attached metal plate. Here, before tack welding, two metal plates 1
The ends of the metal plate 2 are slightly overlapped, and the overlapped lap allowance e is positioned. Although omitted in the figure,
The device for adjusting the lap allowance e uses, for example, a stopper (14 in FIG. 5) such as a gauge bar, and abutting the end surfaces of the respective metal plates against the stopper, thereby forming a slight overlapping portion corresponding to the welding conditions. Set and retained.

After the lap joint is set in this way, tack welding is performed. In this case, the stepped electrode tips 3 and 4 of the spot welding machine pressurize the joint portion 5 at appropriate intervals in the width direction of the plate to form a plurality of half-moon spot welds 6, which are temporarily attached. You. If the temporary fixing is too far away, the plate is gradually deformed by the thermal expansion force generated during the main welding and deviates from a proper position. Therefore, to prevent the plate from escaping, an interval of about 120 mm to 260 mm is desirable. In addition, since the step is provided on the electrode surface of the electrode tip 3 and the electrode tip 4, the butt end face of the metal plate abuts against the contact surface of the step, and the welding is performed in a positioned state. Does not shift.

FIG. 3 shows an example in which mash seam welding is performed by sandwiching the lap joint portion 5 of the temporarily attached metal plate from above and below between the seam welding electrode wheels 7a and 7b. FIG. 4 shows a plane of a lap welded portion of a metal plate subjected to mash seam welding.

After being temporarily attached by spot welding, as shown in FIG. 3, the lap joint is sandwiched between the upper electrode wheel 7a for seam welding and the lower electrode wheel 7b for seam welding while applying a strong pressing force. Simultaneously with energization, the electrode wheel is continuously rotated and crushed to a thickness equal to or close to at least one of the base materials to form a lap seam weld W as shown in the plan view of FIG. .

FIG. 5 shows an embodiment of a welding apparatus for carrying out the method of the present invention. FIG. 3 is a schematic plan view of the apparatus of the present invention in the case where the above-described tack welding step and main welding step are performed automatically. In this case, the two metal plates 1 and 2 are mounted on the work feeder 11 and supplied to the spot welding machine 9 for tacking. The feeding device 11 is used for the next mash seam welding machine 1.
It is moved along the rail 12 by the drive between 0 and 0. When the two metal plates 1 and 2 are supplied on the table of the feeder 11, the welded end faces of both metal plates are abutted against the stopper 14, thereby providing a small overlap width e.
Is set. Except when the overlap margin is set, the stopper 14 retreats from the welding position and waits for the next operation.

In the tacking, a plurality of electrode tips of a spot welding machine are inserted into a lap joint, and a plurality of spot weldings are simultaneously performed. Alternatively, it is also possible to perform tack pot welding at an appropriate interval while the work feeding device 11 feeds the work at a pitch.

When the tack welding is completed, the work is conveyed to the next seam welding process by moving the work feeding device 11. The seam welding machine has two seam welding electrode wheels 7c,
A double roller seam head in which 7d are arranged in parallel is mounted.

FIG. 6 shows an example in which indirect energization is applied as a welding machine type. When the workpiece is supplied into the seam welding machine, the lap joint is supported on the back bar 8 as shown in FIG. One seam welding electrode wheel 7c presses the lap joint, and the other seam welding electrode wheel 7d presses the other mating plate 1 of the lap joint. The lap joint portion 5 is indirectly energized to the electric path formed by the double seam electrode wheel and the back bar 8 by applying a high pressing force by one of the seam welding electrode wheels 7c to reduce the thickness to a predetermined plate thickness. One-dimensional welding is performed in the entire length direction of the joint.

When the main welding is completed, the work is conveyed to the work take-out position by moving the work feeder 11, as shown in FIG. In the meantime, a new work is supplied to the work feeder 11 which stands by in the tacking process, and prepares for the next welding start.

Incidentally, the above-mentioned temporary welding can be performed by temporarily fixing the lap joint portion of the metal plate with reference to the stopper and using the electrode ring for seam welding in the main welding. in this case,
Temporary attachment by a spot welder becomes unnecessary.

As shown in FIG. 6, the back bar 8 is shifted by a shift device in a direction perpendicular to the seam welding line direction (direction of arrow A) to reduce the amount of wear on the contact surface of the back bar. By dispersing in the width direction, local wear deformation can be reduced.

Next, FIG. 7 shows another embodiment of a mash seam welding machine for carrying out the method of the present invention. In this case, the double roll seam head 13 is attached to the industrial robot R.
This is an example of the case where mash seam welding is performed by indirect energization.

The robot hand is equipped with a double seam head 13 in which a welding locus of a lap joint is stored in advance by a robot controller. The robot hand generates a high pressurizing torque required for the mash seam welding. Seam welding is performed by rotating the electrode wheels along a predetermined welding locus.

In this way, the welding trajectory of the curved joint (two-dimensional or three-dimensional welding trajectory) formed not only by the straight joints of the flat plates but also by the wrapping of the pre-pressed pressed products. Mash seam welding is also possible.

[0027]

As described above, according to the method of the first aspect of the present invention, since the tack welding is performed before the mash seam welding step, the clamp of the work feeder can be simplified. This is advantageous in terms of weight and cost.

According to the method of the second aspect of the present invention, the welding is performed in a state where the end face of the lap joint portion is abutted against the contact surface of the stepped electrode, so that it is possible to prevent displacement of the plate during welding.

According to the third aspect of the present invention, the mash welding is performed from the unitary direction on the back bar, and the shunt current is reduced by the indirect energizing method using the double roll seam. The quality of the seam weld can be improved.

Further, according to the apparatus of the present invention, by shifting the back bar, uneven wear of the back bar can be reduced and the life can be extended. In addition, by arranging the work feeding device between the tack welding process and the mash seam welding process, the production can be performed substantially continuously, and the production efficiency can be significantly increased by automation. In addition, the work feeder has been downsized.
Speeding up is possible by reducing the weight. The simplification of the work feeder makes it possible to reduce the space occupied by the machine.

According to the apparatus of the sixth and seventh aspects, one-dimensional or two-dimensional mash seam welding can be performed compared to a conventional tailored blank material manufacturing system.
Three-dimensional welding can be easily realized by an existing robot system, and equipment and cost can be reduced.

[Brief description of the drawings]

FIG. 1 shows an example of a case in which tack welding is performed by spot welding in a state where a lap margin in which two metal plates are stacked is secured in the method of the present invention.

FIG. 2 shows a plan view of a lap welded portion of a tack-welded metal plate.

FIG. 3 shows an example of a case where mash seam welding is performed by sandwiching a lap joint portion of a temporarily attached metal plate with a seam welding electrode wheel.

FIG. 4 is a plan view showing a lap seam welded portion W of a mash seam-welded metal plate;

FIG. 5 shows an embodiment of a mash seam welding apparatus for performing the method of the present invention.

FIG. 6 shows an example in which a welding machine type using indirect energization is applied to mash seam welding.

FIG. 7 is a schematic view showing an example in which a double roll seam head is mounted on an industrial robot to perform mash seam welding by indirect energization as an example for carrying out the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal plate 2 Metal plate 3 Electrode tip 4 Electrode tip 5 Lap joint part 6 Temporary welding part (spot welding part) 7a, 7b Seam welding electrode wheel (up and down) 7c, 7d Seam welding electrode wheel (parallel) 8 Back bar 9 Spot welder 10 Mash seam welder 11 Work feeder 12 Rail 13 Double roll seam head 14 Stopper R Industrial robot e Lap allowance (lap allowance)

Claims (7)

[Claims] 1. A lap joint portion formed by abutting two metal plates and providing a slight overlap margin is preliminarily tack-welded; after the tack-weld, the lap joint is simultaneously performed with the main welding. Mash seam welding method, wherein the seam welding is performed while crushing the portion to a thickness equal to or close to at least one base material thickness. 2. The mash seam welding method according to claim 1, wherein in the case of the tack welding, spot welding is performed by abutting an end face of the lap joint portion to a step formed on an electrode surface. 3. A lap joint portion formed by abutting two metal plates and providing a slight overlap margin is tack-welded at an appropriate interval, and then the joint portion is supported by a back bar and supported by the back bar. Of the twin-type seam welding electrode wheels arranged opposite to each other, one seam welding electrode wheel presses the lap joint portion, and the other seam welding electrode wheel presses the other of the lap joint portion. Press the mating plate,
The welding method is indirect energization, and at the same time as the main welding, the one-electrode wheel for seam welding is used to perform one-dimensional welding in the entire length direction of the joint while crushing to a plate thickness equal to or close to the base metal plate thickness. Seam welding method. 4. A spot welder for tack-welding a lap joint formed by abutting two metal plates with a slight overlap margin at an appropriate interval, and after the spot welding,
The lap joint portion is supported by a back bar, and the lap joint portion supported by the back bar is pressurized by a seam welding electrode wheel and simultaneously pressed to a thickness equal to or close to the thickness of one base material simultaneously with the main welding. A mash seam welding machine that performs one-dimensional welding in the overall length direction of the joint while crushing,
A mash seam welding device, wherein the back bar is shifted by a shift device in a direction perpendicular to the seam welding line direction, thereby reducing the amount of wear of the back bar. 5. The apparatus according to claim 4, wherein the work is moved between the steps of the spot welding machine and the mash seam welding machine by a transfer device. 6. The mash seam welding machine according to claim 4, wherein said mash seam welding machine has an electrode wheel for seam welding mounted on a robot hand in which a welding locus of a lap joint portion is stored in advance. A mash seam welding apparatus, wherein a high pressurizing torque required by the robot is generated by the robot to rotate and drive the electrode wheels along a predetermined welding locus to perform seam welding. 7. An apparatus according to claim 4, wherein a twin seam head is mounted on said robot hand, and a mashing head is provided by said robot hand.
A mash seam welding device characterized by performing indirect seam welding by generating high pressure torque required for seam welding.