JP3402930B2 - Automatic seam welding line copying machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic seam welding line copying apparatus, and more particularly to a seam welding method in which a peripheral portion of a fuel tank is sandwiched between a pair of upper and lower electrode wheels to perform seam welding. The present invention relates to an automatic copying apparatus that corrects a welding trajectory of an electrode wheel at a peripheral portion of a fuel tank by horizontally turning the fuel tank while supporting the fuel tank in a no-load floating state in two orthogonal horizontal directions. . [0002] 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 mutually overlapping peripheral flange portions 4 are temporarily fixed by spot welding at a plurality of positions, and the thus-formed integral fuel tank 2 is set on a special jig 6, and the fuel tank 2 Press the upper surface of the
It is supported on the mold arm 10. The C-shaped arm 10 includes the fixed wall 1
It is supported by the tip of a horizontally bendable arm called an iron man 14 extending in the horizontal direction from 2. The iron man 14 has at least two arm members 1
Reference numerals 4a and 14b extend horizontally via a hinge 16 having a vertical axis, and support the fuel tank 2 movably in a horizontal arbitrary direction with a light force. Exclusive jig 6 and clamp 8
Are C-arms 10 at free rotation axes 18 and 20, respectively.
The copying jig 22 is attached to the lower free rotation shaft 18. The copying jig 22 has a plurality of guided pins 26 protruding from the lower surface of a small plate 24 having a shape similar to a reduced and similar planar shape of the fuel tank 2, and one of the guided pins 26 supports the support arm 28. The guide is linearly guided by a rail 32 fixed to the fixed wall 30 through the intermediary. Each guided pin 26 is arranged in alignment with a vertical line passing through the center of curvature of the corner of the fuel tank 2 as shown in FIG. The illustrated fuel tank 2 has four corner portions R1 to R4, and a total of four guided pins 26 (26a to 26d) protrude from the lower surface of the small plate 24 corresponding to these corner portions R1 to R4. I have. As shown in FIG. 8 (A), the rail 32 has a trough-like shape having a rectangular cross-section with a closed rear end and an open front end. 34,
36 is cut out so that the guided pin 26 enters the rail 32 from one of the two inlets 34 and 36. As shown in FIG. 8 (C), a stopper pin 40 having a lower part supported by a spring 38 and an upper part formed in a slope is disposed in the lower frame of the entrances 34 and 36 so that the stopper pin 40 can be moved into the rail 32 once. The guided pins 26 do not come out. As shown in FIG. 8B, a stopper block 42 is fixedly provided on the inner surface on one side of the front end of the rail 32, and the guided pin 26 which has advanced in the rail 32 is brought into contact with the stopper block 42. Once stopped, in this state, the small plate 2
When 4 rotates 90 ° in the direction of the arrow, the notch 27 of the guided pin 26 faces the stopper block 42 so that the guided pin 26 can pass through. [0005] A 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 of the seam welding machine, and the two electrode wheels 46 are rotated while rotating the electrode wheel 46. The peripheral flange portions 4 that have been in contact with each other by being energized in between have been resistance-welded. When the straight portion L1 of the peripheral flange portion 4 is seam-welded as shown in FIG. 7, the fuel tank 2 moves forward without changing its posture. At this time, the guided pin 26a moves inside 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 prevented by the stopper block 42, and therefore, the fuel tank 2 is moved around the electrode pin 46 around the guided pin 26. It rotates in the direction of the arrow due to the horizontal rotational moment generated by the feed action. When the electrode wheel 46 has finished turning around the corner portion R1, that is, when the fuel tank 2 has been rotated by 90 °, another guided pin 26b enters the rail 32 from the inlet 36 and the peripheral flange portion 4 of the fuel tank 2 Is seam-welded by the electrode wheel 46 in the same manner as described above. When the linear portion L2 is welded, the corner portion R2 is subsequently seam-welded by the electrode wheel 46, and then the guided pin 26c is connected to the inlet 34.
The linear portion L3 enters the rail 32 from above and is seam-welded by the electrode wheel 46. In a conventional automatic seam welding line copying apparatus, a dedicated jig 6 is provided for each type of the fuel tank 2.
Since the profiling jig 22 is required, the dedicated jig 6 and the profiling jig 22 must be newly manufactured every time the shape of the fuel tank 2 is changed. Long production time was required. Therefore, the fuel tank 2 is supported by a robot without using the copying jig 22, and the fuel tank 2 is controlled to be fed in accordance with the progress of the seam welding by the electrode wheel 46, so that the peripheral flange 4 of the fuel tank 2 is controlled. A study has been made to obtain the desired welding line (see Japanese Patent Application Laid-Open No. Hei 7-241684). However, it is extremely difficult to accurately grasp the progress of seam welding by the electrode wheel 46 in real time. This corresponds to the peripheral flange portion 4 of the fuel tank 2.
The thickness of the electrode ring 46 is varied, the peripheral flange portion 4 is softened by energization between the electrode wheels 46, and
6, the rotation speed of the electrode wheel 46 running on the peripheral flange 4 does not match the actual feed distance of the peripheral flange 4, and the feed distance fluctuates minutely and momentarily. is there. The feed control of the fuel tank 2 by the robot may be performed by a teaching method or a feedback control method in which the feed speed or the feed distance of the peripheral flange portion of the fuel tank 2 by the electrode wheel 46 is accurately and real time grasped. As described above, under the situation where the feed speed of the peripheral flange portion 4 fluctuates every moment, control of the robot cannot be performed in time. Also, once the welding line deviates from the regular trajectory, it is not easy to quickly restore it to its original position, and errors due to control delay tend to accumulate, which tends to cause poor welding. There was a problem. An object of the present invention is to completely abandon the concept of the conventional welding jig copying mechanism using the welding jig and the concept of the feed control of the fuel tank 2 depending on the numerical control of the robot. The operator of the seam welding visually checks the welding line and mechanically replaces the work of sending the fuel tank 2, thereby creating expensive copying jigs and complex programs for robots, and troublesome teaching of robots. The object is to eliminate work and the like. [0010] The copying apparatus of the present invention focuses on the fact that the welding line formed by the electrode wheels can be controlled by adjusting the rotation of the fuel tank in the horizontal direction. This will be described with reference to FIGS. 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 and 48 from the bottom.
b, the second and third plates 48b, 4 from the bottom
8c, the first and second linear guides 52, 52, respectively.
54 are provided. The first and second linear motion guides 52 and 54 enable the plates 48a to 48c to slide in a linear direction, and the lower first linear motion guide 52 and the upper second linear motion guide 54 are mutually connected. They are arranged orthogonally. That is, the first translation guide 52 is an X-direction translation guide, and the second translation guide 54 is a Y-direction translation 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 assumed that the scanning control shaft 56 is provided on the lower surface of the zero.
The scanning control shaft 56 is a rotation shaft of a motor capable of precisely controlling a rotation angle, for example, a rotation shaft of a step motor or a servo motor. Then, it is considered that a work 58 to be welded in which two metal sheets are stacked is supported at the lower end of the copying control shaft 56. In such a state that the workpiece to be welded 58 is supported, the peripheral edge of the workpiece (corresponding to the peripheral flange 4 of the fuel tank) is sandwiched between the electrode wheels 46, and the electrode wheel 46 is rotated to seam weld the peripheral edge of the workpiece. . At this time, when the scanning control shaft 56 is rotated in either the forward or reverse direction, the direction of the workpiece 58 with respect to the electrode wheel 46 changes. When this is viewed from the electrode wheel 46 side, the traveling direction of the electrode wheel 46 has changed. FIG. 3 shows an example of the relationship between the rotation 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 linear portion of the peripheral portion of the workpiece 58 to be welded (see FIG. When the control axis is rotated clockwise in accordance with the point A), the electrode wheel 46 is shifted inside the workpiece 58 to be advanced. When the electrode wheel 46 approaches the corner (point B in FIG. 3), and the scanning control shaft 56 is rotated clockwise by 90 °, the electrode wheel 46 makes a curve at 90 ° to the left in the traveling direction. . This is the control principle of the welding line of the present invention. Although the conventional fuel tank 2 is supported by the iron man 14, the iron man 14 cannot support the rotational reaction force of the scanning control shaft 56, so that 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 that supports the work movably in the horizontal direction while supporting the rotational reaction force as in the XY table 50. . The above-described 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 according to the present invention provides a slip between the sewing machine table and the cloth at this time. Further, the function of the hand for turning the fabric corresponds to the copying control axis of the present invention. The welding line automatic copying apparatus according to the present invention is an application of the above-described welding line control principle, and is applied to a peripheral portion of a workpiece.
When seam welding is performed with the edge sandwiched between a pair of upper and lower electrode wheels
Correction of the welding locus of the electrode wheel at the periphery of the workpiece
In an automatic copying machine that performs horizontal turning adjustment,
1st linear guide and 2nd linear guide
Are arranged perpendicular to each other, and
Allow any horizontal movement while constraining the movement of
An XY table and a scanning control axis having a main axis in a direction orthogonal to the movement allowable direction of the XY table are vertically overlapped, and one of the XY table and the scanning control axis is supported on a base floor surface, and Attach a dedicated jig for supporting a work having a part to be seam-welded, and make the same or similar contour as the scheduled welding line of the work.
Align the template with the work with the dedicated jig
And a pair of upper and lower seam welders.
Within the vertical plane commonly including the axis of the electrode ring, and
A reference member is fixedly placed at a position facing the contour of the rate.
The gap distance between the contour of the template and the reference member.
A distance measuring sensor to detect is provided,
The scanning control shaft is rotationally controlled so that the gap distance is constant . An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 4A, a copying control shaft 74 is provided on a base floor 70 via a base 72. The scanning control shaft 74 is a rotation shaft such as a step motor or a servo motor capable of precisely controlling a rotation angle. The XY table 50 is supported on the upper end of the scanning control shaft 74. The XY table 50 is the same as that described above, and the first plate 48 a from the bottom is fixed to the upper end of the scanning control shaft 74. An exclusive jig 6 is fixed on the upper surface of the XY table 50, and the fuel tank 2 is positioned and fixed on the exclusive jig 6. The XY table 50 can be replaced with another mechanism as long as it can move in any horizontal direction but restricts the movement in the horizontal turning direction. For example, as shown in FIG. The universal joint 76 is provided 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.
8 is disposed 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 below the dedicated jig 6 as shown in FIG. The template 88 is formed of a plate having a contour similar to the contour of the expected welding line of the peripheral flange portion 4 of the fuel tank 2 and a reduced shape.
It is arranged horizontally so as to be aligned with the fuel tank 2, that is, so that the corresponding sides face in the same direction. On the other hand, a fixed arm 90 extends in the horizontal direction from the main body of the seam welding machine 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 including the axis of the pair of upper and lower electrode wheels 46 in common, and is opposed to the contour of the template 88. In the vicinity of the reference member 92 at the tip of the fixed arm 90, a distance measuring sensor 94 is attached. The distance measuring sensor 94 is provided between the contour of the template 88 and the reference member 9.
2 is measured. Next, control of the scanning control shaft 74 will be described.
When the peripheral flange portion 4 of the fuel tank 2 is seam-welded without rotating the scanning control shaft 74, the welding line is basically straight, but in this state, an error in the welding line due to a variation in thickness of the peripheral flange portion 4 or unevenness. Cannot be modified. When the front end of the welding line deviates from the scheduled welding line, the distance 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 that the change in the width of the interval is restored. Further, welding of the corner portion of the peripheral flange portion 4 of the fuel tank 2 is also performed by rotation of the copying control shaft 74. That is, the electrode wheel 46
At the same time as passing through the welding start point at the corner, the distance between the contour of the template 88 and the reference member 92 is widened. The distance measuring sensor 94 continuously detects the degree of the widening of the distance and returns the width to the original state. Thus, the scanning control shaft 74 is rotated by control means (not shown). The scanning control shaft 74 can be controlled by means other than the above-mentioned template 88, reference member 92 and distance measuring sensor 94. Generally, the seam welding scheduled line of the fuel tank 2 and the actual welding It suffices if there is a sensor for detecting a deviation from the front end of the line, and control means for controlling the rotation of the scanning control shaft 74 based on the output from the sensor so as to make the deviation zero. FIG. 5 is a block diagram of this general control. A signal from an electrode wheel passing position detection sensor 82 is introduced into a deviation calculating means 84, and based on the calculation result of the deviation calculating means 84, a drive control means 86 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 equivalent to detecting the deviation between the scheduled seam welding line and the actual front end of the welding line. Therefore, it is also possible to use a sensor that directly detects the position of the front end of the welding line of the fuel tank 2 instead of the distance measuring sensor 94. While the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above embodiment, the scanning control axis 7
4 is arranged on the lower side, and the XY table 50 is arranged on the upper side. Conversely, the XY table 50 is arranged on the lower side, the copying control shaft 74 is arranged on the upper side, and the exclusive jig 6 is fixed to the upper end of the copying control shaft 74. May be. In this case, the position of the scanning control shaft 74 moves due to its rotation (rotation). As described above, according to the present invention, the direction in which the welding line is formed on the workpiece is controlled only by the rotation of the scanning control shaft, so that the conventional expensive copying jig or robot can be used. There is no need for complicated programs at all, and a great rationalization effect can be achieved.

BRIEF DESCRIPTION OF THE 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 scanning control shaft. FIG. 3 is a plan view of a workpiece showing welding line copying control. FIG. 4A is a side view of an automatic seam welding line copying apparatus,
(B) is a side view of the support means using a universal joint, (C)
FIG. 4 is a perspective view of a support unit 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 scanning 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 of the rail, and FIG. 8C is a longitudinal sectional view of a rear end of the rail. [Description of Signs] 2 Fuel tank 6 Special jig 44 Seam welder 46 Electrode wheel 50 XY table 70 Base floor 74 Copying control shaft 88 Template 90 Fixed arm 92 Reference member 94 Distance measuring sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 11/06 B23K 11/24

Claims (1)

(57) [Claims] [Claim 1] A peripheral portion of a work is sandwiched between a pair of upper and lower electrode wheels.
Of the electrode ring at the periphery of the workpiece during seam welding
Automatic profiling that corrects the tangent locus by adjusting the horizontal rotation of the work
In the apparatus, the first straight line is inserted into the upper and lower gaps of the three-layer plate.
Before the moving guide and the second linear guide are arranged orthogonal to each other.
Any water with the movement of the work in the horizontal
An XY table that allows movement in the horizontal direction;
And a scanning control axis having a main axis in a direction orthogonal to the movement allowable direction of the bull is vertically overlapped, and one of the XY table and the scanning control axis is supported on a base floor surface, and the other is seam-welded to the other. A dedicated jig for supporting a workpiece having a part is attached, and
Templates with the same or similar outline
Attach it to the jig in alignment with the work, and
Vertical including the axis of the pair of upper and lower electrode wheels of the
At a position in the plane that faces the contour of the template
A reference member is fixedly disposed, and the contour of the template is
A distance measurement sensor that detects the gap distance with the reference member is arranged,
Before performing seam welding, make sure that the gap distance is constant.
The scanning control axis is rotationally controlled.
The automatic seam welding line copying apparatus according to claim 1 .