JPH09314345A - Seam weld line automatic copying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a high cost copying jig required for seam welding and complicated program, etc., for a robot to support a work. SOLUTION: An XY table 50 as a support means of a fuel tank 2, which allows movement in arbitrary horizontal direction and restricts movement in horizontal turning direction, and a copying control shaft 74 having a spindle in the direction orthogonal to the moving allowable direction of XY table 50 are stacked up/down. Either one of the XY table 50 or copying control shaft 74 is supported with a base floor face 70, on the other, a special jig 6 to support the fuel tank 2 having a part to be seam welded is mounted. A forming direction of the weld line in fuel tank 2 is changed/controlled by rotation of the copying control shaft 74. Control of the copying control shaft 74 is executed based on the output of a range sensor 94 to detect the interval between a template 88 mounted to the special jig 6 and a reference member 92.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seam welding line automatic copying apparatus, and more particularly, when performing seam welding by sandwiching a peripheral portion of a fuel tank with a pair of upper and lower electrode wheels, the fuel tank is arranged in two horizontal directions. The present invention relates to an automatic copying apparatus in which a welding locus of an electrode wheel on a peripheral portion of a fuel tank is corrected by horizontally swinging and adjusting the fuel tank while supporting the fuel tank in an unloaded floating state.

[0002]

2. Description of the Related Art As shown in FIG. 6, a fuel tank 2 comprises an upper half 2a and a lower half 2b formed by a sheet metal press. To manufacture the fuel tank 2, these upper halves 2a
And the lower half 2b are overlapped with each other, and the peripheral flange portions 4 that are overlapped with each other are temporarily fixed by spot welding at a plurality of points, and the integrated fuel tank 2 thus formed is set on the dedicated jig 6, and the fuel tank 2 Press the upper surface of the with the clamp 8 to C
It is supported by the mold arm 10. The C-shaped arm 10 has a fixed wall 1
It is supported at the tip of a horizontally bendable arm called an iron man 14 which extends horizontally from 2. This iron man 14 has at least two arm members 1
4a and 14b are horizontally extended via a hinge 16 having a vertical axis, and support the fuel tank 2 movably in an arbitrary horizontal direction with a light force. Dedicated jig 6 and clamp 8
Is a C-shaped arm 10 with free rotating shafts 18 and 20, respectively.
A copying jig 22 is attached to the lower free rotating shaft 18. The copying jig 22 is formed by projecting a plurality of guided pins 26 on the lower surface of a small plate 24 which is close to a reduction-like shape in plan view of the fuel tank 2, and one of the guided pins 26 has a support arm 28. The rail 32 is linearly guided by a rail 32 fixed to the fixed wall 30.

As shown in FIG. 7, each guided pin 26 is arranged in alignment with a vertical line passing through the center of curvature of the corner portion of the fuel tank 2. The illustrated fuel tank 2 has four corners R1 to R4, and a total of four guided pins 26 (26a to 26d) are projectingly provided on the lower surface position of the small plate 24 corresponding to these corners R1 to R4. There is.

As shown in FIG. 8 (A), the rail 32 has a gutter shape with a rear end closed and a front end open having a groove having a rectangular cross section. Two entrances are provided on one side surface of the rear end of the rail 32 and the middle part. 34,
36 is cut out so that the guided pin 26 can enter the rail 32 from either of these two inlets 34, 36. As shown in FIG. 8C, a stopper pin 40 having a lower portion supported by a spring 38 and an upper portion formed in a slope shape is provided on the lower frame of the inlets 34 and 36, and the stopper pin 40 once enters the rail 32. The guided pin 26 does not come out. Further, as shown in FIG. 8B, a stopper block 42 is fixedly provided on the inner surface on one side of the front end portion of the rail 32, and the guided pin 26 moving forward in the rail 32 is brought into contact with the stopper block 42. Once stopped, the electrode plate 46 feeds the small plate 2 in this state.
When 4 rotates 90 ° in the direction of the arrow, the notch 27 of the guided pin 26 faces the stopper block 42 to allow the guided pin 26 to pass.

The conventional seam welding method for the fuel tank 2 is as follows:
With the fuel tank 2 supported as described above, the peripheral flange portion 4 of the fuel tank 2 is sandwiched between a pair of upper and lower electrode wheels 46, 46 of the seam welding machine, and the electrode wheels 46 are rotated while rotating the electrode wheels 46. The peripheral flange portions 4, which were energized and abutted against each other, were resistance-welded. The fuel tank 2 advances without changing its posture when the straight line portion L1 of the peripheral flange portion 4 is seam-welded as shown in FIG. At this time, the guided pin 26a moves in the rail 32 toward the front end. However, when the electrode wheel 46 reaches the corner portion R1 of the peripheral flange portion 4, the movement of the guided pin 26 is blocked by the stopper block 42, so that the fuel tank 2 moves the electrode wheel 46 around the guided pin 26. It rotates in the direction of the arrow due to the horizontal rotation moment generated by the feeding action. When the electrode wheel 46 has finished turning around the corner R1, that is, when the fuel tank 2 has finished rotating by 90 °, another guided pin 26b enters the rail 32 through the inlet 36, and the peripheral flange portion 4 of the fuel tank 2 is inserted. The straight line portion L2 is seam welded by the electrode wheel 46 in the same manner as above. When the straight line portion L2 is welded, the corner portion R2 is subsequently seam welded by the electrode wheel 46, and then the guided pin 26c is inserted into the inlet 34.
From inside the rail 32, the straight portion L3 is seam welded by the electrode wheel 46.

[0006]

In the conventional seam welding line automatic copying apparatus, a dedicated jig 6 is provided for each type of fuel tank 2.
Since the copying jig 22 is required, the dedicated jig 6 and the copying jig 22 must be newly manufactured every time the shape of the fuel tank 2 is changed, and in particular, the manufacturing of the copying jig 22 is expensive. Needed a long production period.

Therefore, the fuel tank 2 is supported by a robot without using the copying jig 22, and the fuel tank 2 is fed and controlled in accordance with the progress of the seam welding by the electrode wheels 46 to control the peripheral flange portion 4 of the fuel tank 2. A study has been made to obtain a desired welding line (see Japanese Patent Application Laid-Open No. 7-241684).

However, it is extremely difficult to accurately grasp the progress of seam welding by the electrode wheel 46 in real time. This is the peripheral flange portion 4 of the fuel tank 2.
Unevenness in the plate thickness, softening of the peripheral flange portion 4 due to energization between the electrode wheels 46, and further the electrode wheel 4
Since abrasion of 6 occurs, the rotation speed of the electrode wheel 46 running on the peripheral flange portion 4 does not match the actual feed distance of the peripheral flange portion 4, and the feed distance fluctuates minute by minute. is there. For the feed control of the fuel tank 2 by the robot, a method by teaching, a method of feedback control by grasping the feed speed or feed distance of the peripheral flange portion of the fuel tank 2 by the electrode wheel 46 accurately and in real time are conceivable. As described above, under the situation where the feed rate of the peripheral flange portion 4 fluctuates from moment to moment, the control of the robot is too late. In addition, if the welding line once deviates from the normal trajectory, it is not easy to quickly restore it to the original position, and errors due to control delays tend to accumulate, resulting in poor welding. There was a problem.

The object of the present invention is to completely abandon the conventional concept of a welding line copying mechanism using a copying jig and the concept of feed control of the fuel tank 2 which depends on the numerical control of the robot, and a completely new idea, that is, , The seam welding operator mechanically replaces the work contents of sending the fuel tank 2 while visually confirming the welding line, thereby creating an expensive copying jig and a complicated program for the robot, and the troublesome teaching of the robot. There is no need for work.

[0010]

The copying apparatus of the present invention focuses on the fact that the welding line by the electrode wheels can be controlled by rotationally adjusting the fuel tank in the horizontal direction. 3 will be described. FIG. 1 shows an XY table 50 in which three horizontal plates 48a to 48c are vertically stacked, and the first and second plates 48a, 48 from the bottom are shown.
The second and third plates 48b, 4 between the b and the bottom
8c, the first and second linear motion guides 52,
54 is provided. The first and second linear motion guides 52 and 54 are capable of sliding the plates 48a to 48c in a linear direction, and the lower first linear motion guide 52 and the upper second linear motion guide 54 are mutually arranged. They are arranged orthogonally. That is, the first linear motion guide 52 is an X-direction linear motion guide, and the second linear motion guide 54 is a Y-direction linear motion guide.

A copying control shaft 56 is provided on the upper or lower surface of the XY table 50. In FIG. 2, the XY table 5
It is considered that the copying control shaft 56 is arranged on the lower surface of 0.
The copying control shaft 56 is a rotation shaft of a motor whose rotation angle can be precisely controlled, and is, for example, a rotation shaft of a step motor or a servo motor. Then, it is considered that the work piece 58 to be welded, which is formed by stacking two sheet metals, is supported on the lower end of the copying control shaft 56.

While the work 58 to be welded is supported, the work peripheral portion (corresponding to the peripheral flange portion 4 of the fuel tank) is sandwiched by the electrode wheels 46, and the electrode wheels 46 are rotated to seam weld the work peripheral portions. . At this time, if the scanning control shaft 56 is rotated in either forward or reverse directions, the orientation of the workpiece 58 to be welded with respect to the electrode wheel 46 changes. When viewed from the side of the electrode wheel 46, this means that the traveling direction of the electrode wheel 46 has changed. FIG. 3 exemplifies the relationship between the rotating direction of the scanning control shaft 56 and the traveling direction of the electrode wheel 46. When the electrode wheel 46 is traveling along the straight line portion of the peripheral edge of the workpiece 58 to be welded (see FIG. 3). When the control axis is rotationally adjusted in the clockwise direction following the point A), the electrode wheel 46 shifts inside the workpiece 58 to be welded. When the electrode wheel 46 approaches the corner (point B in FIG. 3) and the control shaft 56 is rotated clockwise by 90 °, the electrode wheel 46 turns to the left at 90 ° in the traveling direction. . This is the control principle of the welding line of the present invention.

Although the conventional fuel tank 2 was supported by the iron man 14, since the iron man 14 cannot support the rotational reaction force of the copying control shaft 56, the XY table 50 as shown in FIG. Or, a supporting means having a function equivalent to this is required. Plate 4
By arranging various known link mechanisms and universal joints between 8a to 48c, it is possible to realize a configuration in which the work is supported movably in the horizontal direction while supporting the rotational reaction force as in the XY table 50. .

The above control of the welding line can be easily understood by imagining a cloth feeding operation by a sewing machine. The feed direction of the sewing machine is always straight, but the stitch direction is changed by turning the fabric horizontally and changing the angle of the fabric fed to the needle. The XY table of the present invention provides the sliding between the sewing machine table and the cloth at this time. The function of the hand that turns the fabric corresponds to the copying control shaft of the present invention.

The welding line automatic copying apparatus according to the present invention is an application of the above-mentioned welding line control principle, and includes support means for allowing movement in an arbitrary horizontal direction but restraining movement in a horizontal turning direction, The copy control axis having a main axis in a direction orthogonal to the movement permitting direction of the support means is vertically overlapped, and either one of the support means or the copy control axis is supported on the base floor surface, and the other is seam welded. Attached a jig that supports the work that has the part to be welded, and a sensor that detects the deviation between the seam welding planned line of the work and the front end of the actual welding line is provided, and the deviation is zero based on the output from the sensor. In order to achieve this, the copying control shaft is controlled to rotate.

The supporting means may be an XY table in which a first linear motion guide and a second linear motion guide are arranged in a space between two upper and lower portions of a three-layer plate so as to intersect each other.

In order to detect the deviation between the planned seam welding line and the actual front end of the welding line, a template having the same or similar contour as the planned welding line of the work is attached to a dedicated jig in alignment with the work and the seam welding is performed. A reference member is fixedly arranged at a position facing the contour of the template in a vertical plane that commonly includes the axis lines of a pair of upper and lower electrode wheels of the machine, and the gap distance between the contour of the template and the reference member is detected. A distance measuring sensor is provided. Then, based on the output from the distance measuring sensor, the copying control shaft is rotationally controlled so that the gap distance becomes constant during seam welding.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 4 (A), a copying control shaft 74 is arranged on a base floor 70 via a table 72. The copying control shaft 74 is a rotation shaft such as a step motor or a servo motor whose rotation angle can be precisely controlled. The XY table 50 is supported on the upper end of the scanning control shaft 74. The XY table 50 is similar to that described above, and the first plate 48a from the bottom is fixed to the upper end of the scanning control shaft 74. A dedicated jig 6 is fixed on the upper surface of the XY table 50, and the fuel tank 2 is positioned and fixed on the dedicated jig 6.

The XY table 50 can be replaced with another mechanism as long as it allows movement in an arbitrary horizontal direction but restrains movement in the horizontal turning direction. For example, as shown in FIG. 4 (B). The universal joint 76 is disposed between the upper and lower plates 48d and 48e, or the parallel link mechanism 7 is provided between the upper and lower plates 48f and 48g as shown in FIG. 4C.
8 is arranged horizontally, one end 78a of the parallel link 78 is connected to the lower plate 48f, and the other end 78b is slidably engaged with the groove 80 formed on the lower surface of the upper plate 48g. It can be replaced.

A template 88 is fixed to the lower part of the dedicated jig 6 as shown in FIG. 4 (A). The template 88 is composed of a plate having a contour similar to the contour of the planned welding line of the peripheral flange portion 4 of the fuel tank 2,
Aligned with the fuel tank 2, that is, arranged horizontally so that the corresponding sides face the same direction.

On the other hand, a fixed arm 90 extends horizontally from the main body of the seam welder 44, and a reference member 92 is attached to the tip of the fixed arm 90. The reference member 92 is located in a vertical plane that commonly includes the axes of the pair of upper and lower electrode wheels 46, and is opposed to the contour of the template 88. A distance measuring sensor 94 is attached near the reference member 92 at the tip of the fixed arm 90. The distance measuring sensor 94 has a contour of the template 88 and the reference member 9
The gap distance between the two is measured.

Next, the control of the scanning control shaft 74 will be described.
If the peripheral flange portion 4 of the fuel tank 2 is seam-welded without rotating the copying control shaft 74, the welding line is basically a straight line. However, if it is left as it is, an error in the welding line due to variation in thickness of the peripheral flange portion 4 or unevenness Can't be fixed. When the front end of the welding line deviates from the planned welding line, the interval between the reference member 92 and the contour of the template 88 changes to either wide or narrow. This is detected by the distance measuring sensor 94, and the scanning control shaft 74 is rotationally controlled so as to restore the change in the width of the interval. Further, the welding of the corner portion of the peripheral flange portion 4 of the fuel tank 2 is also performed by the rotation of the copying control shaft 74. That is, the electrode wheel 46
At the same time as the welding start point of the corner passes, the distance between the contour of the template 88 and the reference member 92 widens, but the distance measuring sensor 94 continuously detects the extent of this distance and restores the widening. Thus, the copying control shaft 74 is rotated by the control means (not shown).

The copying control shaft 74 can be controlled by means other than the template 88, the reference member 92 and the distance measuring sensor 94 described above. Generally, the seam welding planned line of the fuel tank 2 and the actual welding are performed. A sensor for detecting the deviation from the front end of the line and a control means for controlling the rotation of the copying control shaft 74 so as to reduce the deviation to zero based on the output from this sensor may be provided. FIG. 5 is a block diagram of this general control, in which the signal from the electrode wheel passage position detection sensor 82 is introduced into the deviation calculation means 84, and the drive control means 86 is operated based on the calculation result of this deviation calculation means 84. The scanning control shaft 74 is rotated by a predetermined angle. The distance measuring sensor 94 detects the distance between the template 88 and the reference member 92, which is synonymous with detecting the deviation between the planned seam welding line and the actual front end of the welding line. Therefore, instead of the distance measuring sensor 94, it is possible to use a sensor that directly detects the position of the front end of the welding line of the fuel tank 2.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications can be made. For example, in the above embodiment, the copy control shaft 7
4 is arranged on the lower side and the XY table 50 is arranged on the upper side. On the contrary, the XY table 50 is arranged on the lower side and the copying control shaft 74 is arranged on the upper side, and the dedicated jig 6 is fixed to the upper end of the copying control shaft 74. You may. In this case, the position of the scanning control shaft 74 moves due to its rotation (rotation).

[0025]

As described above, according to the present invention, the forming direction of the welding line with respect to the work is controlled only by the rotation of the copying control axis, so that the complicated program for the conventional expensive copying jig or robot is used. It becomes unnecessary, and a big rationalization effect can be exhibited.

[Brief description of drawings]

FIG. 1 is a perspective view of an XY table.

FIG. 2 is a perspective view showing a relationship between a welding wheel and a copy control shaft.

FIG. 3 is a plan view of a workpiece showing welding line copying control.

FIG. 4 (A) is a side view of the seam welding line automatic copying apparatus,
(B) is a side view of a supporting means using a universal joint, (C)
FIG. 6 is a perspective view of a supporting means using a link mechanism.

FIG. 5 is a control block diagram of a scanning control axis.

FIG. 6 is a side view of a conventional welding line copying control device.

FIG. 7 is a plan view of a fuel tank.

8A is a perspective view of a rail, FIG. 8B is a plan view of a front end portion of the rail, and FIG. 8C is a longitudinal sectional view of a rear end portion of the rail.

[Explanation of symbols]

 2 Fuel tank 6 Dedicated jig 44 Seam welder 46 Electrode wheel 50 XY table 70 Base floor surface 74 Copy control axis 88 Template 90 Fixed arm 92 Reference member 94 Distance measuring sensor

Claims (3)

[Claims] 1. A support means for allowing movement in an arbitrary horizontal direction, but restraining movement in a horizontal turning direction, and a copying control shaft having a main shaft in a direction orthogonal to the movement allowance direction of the support means are vertically stacked. While supporting either one of the support means or the copy control shaft on the foundation floor surface, a dedicated jig for supporting a work having a portion to be seam welded is attached to the other, and the seam welding planned line of the work and the actual The seam is characterized in that a sensor for detecting a deviation from the front end of the welding line is provided, and a control means for controlling the rotation of the copying control shaft so as to make the deviation zero based on the output from the sensor. Welding line automatic copying device. 2. The supporting means comprises two layers above and below the three-layer plate.
The seam welding line automatic copying apparatus according to claim 1, wherein the first linear motion guide and the second linear motion guide are arranged in one gap so as to intersect each other. 3. A template having a contour that is the same as or similar to the planned welding line of the work is attached to the dedicated jig so as to be aligned with the work, and the axes of a pair of upper and lower electrode wheels of a seam welder are commonly included. A reference member is fixedly arranged at a position facing the contour of the template in a vertical plane, and a distance measuring sensor for detecting a gap distance between the contour of the template and the reference member is arranged to perform seam welding. The automatic seam welding line copying apparatus according to claim 1, wherein the copying control shaft is rotationally controlled so that the gap distance becomes constant during the operation.