JP3459292B2 - C-type spot welding gun device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a C-type spot welding gun device for welding a plate-like work having a three-dimensional curved surface.

[0002]

2. Description of the Related Art As a conventional C-type spot welding gun device of this type, for example, there is a device disclosed in Japanese Patent Publication No. 62-35867. This is as shown in FIG.
It is an apparatus for welding a vehicle body floor panel 52, for example, a tunnel portion 52a in a vehicle body welding assembly line. In order for the electrode to hit the work surface perpendicularly, it is necessary to perform accurate dressing on the axis of the electrode, but it is difficult to keep this in an ideal state at all times.
As a countermeasure, this C-type spot welding gun device 51
An equalizing mechanism 55 is provided on a bracket 54 provided on the tip of a wrist 53 of a Cartesian coordinate type industrial robot.

The equalizing mechanism 55 has a central base 57 slidably guided by an inclined guide rod 56. An air cylinder 57a is provided in the center base 57, and the center base 57 is provided so as to be pressed and moved to the left in FIG. Further, a spring 57b is also built in, and is provided so as to press and urge the central base portion 57 to the right in FIG.

Further, a long lower arm 58 is provided below the central base 57, and the upright portion 5 at the tip is provided.
8a is guided below the tunnel portion 52a. A lower electrode 59 is provided at the tip of the rising portion 58a in a direction perpendicular to the inclined surface 52b of the tunnel portion 52a.

On the other hand, at the tip of the upper arm 60 provided above the central base 57, an auxiliary arm 62 is provided with a hinge pin 61, and an auxiliary arm 62 is supported by a trunnion.
It is rotatably provided by 3. Further, a pressure cylinder 65 to which an upper electrode 64 is attached is provided at the tip of the auxiliary arm 62 so that the upper electrode 64 can be moved toward and away from the lower electrode 59. Further, the rotation cylinder 63 allows the axis of the upper electrode 64 to move to the lower electrode
It is adapted to avoid it by matching it with 9 or rotating it upward.

Further, the direction of the inclined guide rod 56 is provided so as to coincide with the axial direction of the lower electrode 59. Thus, the upper electrode 64, the pressure cylinder 65,
Auxiliary arm 62, upper arm 60, central base 57,
The lower arm 58, the upright portion 58a, the lower electrode 59, and their related parts constitute a C-type spot welding gun 66.

In the above structure, the floor panel 52 is first carried in and positioned at the position shown in FIG. 8 by another robot. Next, the rotating cylinder 63 and the pressurizing cylinder 65 are contracted to avoid the upper electrode 64 from the lower electrode 59 as shown by the chain double-dashed line in the figure, and then the wrist 53 of the industrial robot is operated. Then, the lower electrode 59 is brought into contact with a desired welding position on the inclined surface 52b of the tunnel portion 52a as shown in the drawing. At this time, after the wrist 53 is positioned so that the spring 57b acts appropriately, the rotary cylinder 63 is extended so that the shaft center of the upper electrode 64 becomes lower.
Align with 9 axis.

Then, the pressurizing cylinder 65 is extended,
The inclined surface 52b is pressed and clamped. At this time, for example, when the floor panel 52 is displaced or the teaching error of the robot occurs, the air cylinder 57a and the spring 57b of the equalizing mechanism 55 appropriately expand and contract, so that the axes of the upper electrode 64 and the lower electrode 59 have inclined surfaces. It can be held perpendicularly to 52b and can be clamped with an appropriate pressure. Therefore, good spot welding is performed by applying a welding current.

[0009]

In the conventional C-type spot welding gun device 51 described above, the equalizing mechanism 55 is mounted, but only the two-dimensional posture control is possible. Therefore, for example, it is impossible to follow the posture control for a work including a three-dimensional shape such as a sunroof condenser of an automobile. Therefore, if the upper electrode and the lower electrode do not hit the workpiece weld perpendicularly, (b) of FIG.
As shown in FIG. 2, since the welding indentation 25 becomes large and the welding burr 26 and the welding distortion 27 are generated, the welding burr 2 is formed by sander.
6 must be removed or the weld distortion 27 must be corrected with a hammer. Therefore, there is a problem that work efficiency is reduced.

Further, the conventional apparatus has no means for causing the electrode to bite into the work at an appropriate timing when the work is melted. In other words, no measures have been taken to improve the responsiveness of the electrodes. If the timing for biting the electrode into the work is improper and delayed, the welding will be insufficient and the reliability will be reduced. further,
A set of two secondary conductors is introduced from the transformer in order to pass a welding current to the upper and lower electrodes. However, when the secondary conductors are arranged in parallel, the direction of the current is opposite. At this time, as shown in FIG. 6A, the forces of repelling each other act according to Faraday's law.

When this repulsive force is generated, it interferes with the above-mentioned equalizing action and causes welding burrs 26 and welding distortion 27. When these welding burrs and welding distortions occur, there is a problem that the work efficiency is lowered to correct them. However, in reality, no effective measures have been taken against this point. Therefore, the present invention
In view of the above-mentioned conventional problems, the equalizing action is effectively exerted even on a work including a three-dimensional shape, the responsiveness of the electrode is good, and the repulsive force of the secondary conductor does not have a bad influence. An object is to provide a spot welding gun device.

[0012]

Therefore, according to the present invention, the upper electrode and the lower electrode are supported by a C-shaped arm, and the work is sandwiched between the upper electrode and the lower electrode and welded by energizing the workpiece. Type spot welding gun device, a gun mounting unit that is hung from a main body by a suspension spring and is vertically movable with respect to the main body by a driving means provided between the main body and the main body; This gun has a framed gun arm, the lower electrode of the gun arm is provided with the lower electrode and the clamped material, and the upper end of the gun arm is coaxial with the lower electrode. It is assumed that a pressure cylinder having an upper electrode movably mounted thereon is provided, and the gun mounting unit is provided with a clamper for grasping the material to be clamped.

The driving means may be an air cylinder. Further, the upper electrode is attached to the pressure cylinder via a pressure unit guided along the gun arm, and in this pressure unit, the upper electrode and the piston rod of the pressure cylinder are connected with the pressure spring interposed. Can be allowed to.

The upper electrode has a first conductive plate extending from the main body toward the gun arm, and a substantially U-shaped first flexible plate provided between the tip of the first conductive plate and the upper electrode. The lower electrode is connected to a power source through a first secondary conductor formed of a flexible plate, and the lower electrode has a second conductive plate extending from the main body toward the gun arm, the tip of the second conductive plate, and the first arm of the gun arm. 1 a second secondary conductor consisting of a substantially U-shaped upper and lower flexible second plate provided between positions above the flexible plate and a gun arm, and sequentially connected to a power source, The first conductive plate and the second conductive plate may be fixed to each other with an insulator interposed therebetween.

[0015]

First, the pressurizing cylinder is contracted to separate the upper electrode from the lower electrode, and the driving means is operated to move the gun mounting unit downward. Then, the work is handled between the upper electrode and the lower electrode. Next, the upper electrode is pushed down by the pressure cylinder, and at the same time, the gun mounting unit is pulled up by the driving means. At this time, the suspension spring acts to accelerate the initial speed of the unit mounting the gun. As a result, the work is clamped by the upper electrode and the lower electrode with a slight pressure.

Next, when the material to be clamped of the gun is released from being fixed by the clamper of the gun mounting unit, the gun hung by the gun spring is in a so-called weightless state. Then, when the air pressure of the pressurizing cylinder is increased to the energizing pressure, the work is strongly clamped by the upper electrode and the lower electrode, and the gun automatically moves to a position where the upper electrode and the lower electrode hit the work vertically. Change your posture. That is, the equalizing operation is performed. After that, when the upper electrode and the lower electrode are energized, the welding point of the work is melted by resistance heat. As a result, the gun supported by the gun spring is three-dimensionally equalized, so that the welding indentation is small and welding burrs and welding distortion are effectively suppressed.

When a pressure unit is provided between the upper electrode and the pressure cylinder, the spring force of the pressure spring interposed between the piston rod and the upper electrode causes
The upper electrode and the lower electrode bite into the melted work, and the work is effectively pressure welded. That is, the electrode timing delay is prevented, high responsiveness is exhibited, and perfect spot welding is performed.

Further, the upper electrode is connected to a power source through a first secondary conductor composed of a first conducting plate and a first U-shaped flexible upper and lower flexible plate, and the lower electrode is connected to the second conductive plate. When the power is connected to the power source through the second secondary conductor, which is composed of a conductive plate and a second U-shaped flexible second flexible plate extending above the gun arm, and the gun arm, Of the second flexible plate, the second flexible plate, the second flexible plate, the second flexible plate, the second conductive plate, the first flexible plate, the first flexible plate to the upper electrode The flow returns to the main body via the guide plate.

Of these, the first U-shaped first flexible plate of the first secondary conductor and the first conductive plate are close to the gun arm, but the currents are orthogonal to each other, so the attraction force by Faraday's law or Repulsion does not occur. Further, although the first conductive plate and the second conductive plate extend in parallel with each other, since they are fixed by sandwiching the insulator, even if the repulsive force according to Faraday's law acts, the gun and the upper electrode, the lower electrode Does not interfere with the equalizing operation of.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall perspective view showing an embodiment of the present invention. 2 shows the details of the gun. First, a mounting plate 2 that protrudes from the front surface of the main body 1 and extends in the vertical direction is fixedly provided to the main body 1. A ceiling portion 2a protruding forward is provided at the upper end of the mounting plate 2. Further, on the front surface of the mounting plate 2, there is provided a gun mounting unit 3 supported by a linear guide so as to be vertically movable. The gun mounting unit 3 is suspended from the ceiling portion 2a by two suspension springs 4 and is vertically displaced by an air cylinder 5 provided near the ceiling portion 2a.

On the other hand, a gun 6 is suspended from the ceiling portion 2a by a gun spring 7. The gun 6 is provided with plate-shaped gun arms 8 extending on both sides and extending in the vertical direction to form a frame. The lower end of the gun arm 8 is provided with a lower electrode 9 which is bent in an L shape and has its tip facing upward, and a clamped material 10 below the lower electrode 9. The clamped material 10 can be clamped or released by a clamper 11 provided at the lower end of the gun mounting unit 3. As a result, the posture of the gun 6 is restrained when it is clamped and fixed, and the gun 6 can swing three-dimensionally while being suspended by the gun spring 7 when the clamp is released.

A pressure cylinder 12 having a piston rod 12a facing downward is attached to the upper end of the gun arm 8. In addition to the clamper 11 described above, the gun mounting unit 3 is also provided with clampers 31 and 32 for clamping the pressure cylinder 12, and the pressure cylinder 12 is clamped and released in synchronization with the clamper 11. .

Further, as shown in FIG. 3, the gun arm 8 is provided with a pressurizing unit 14 which is connected to a pressurizing cylinder 12 and which is guided by a plurality of ball splines 13 and is vertically movable. An upper electrode 15 having a shank 15a facing downward is provided at the lower end of the pressure unit 14. The pressure unit 14
A pressure spring 16 made up of a compression spring is provided inside, and the upper end of the pressure spring 16 has an adapter 12 provided at the tip of the piston rod 12a.
It is in contact with b. As a result, the pressing force of the pressure cylinder 12 is applied to the upper electrode 15 via the pressure spring 16.
To join.

Next, referring to FIGS. 4 and 5, a route in which the welding current is supplied from the secondary coil of the power transformer 17 provided in the main body 1 by the pair of secondary conductors 18 will be described. In the secondary conductor 18a, the first conductor plate 19 is first provided in the main body 1 and then the first conductor plate 19 is formed.
5, a first U-shaped flexible plate 20 made of, for example, an ounce copper plate, which bends up and down, is provided at the tip end of the shank 15a of the upper electrode 15.
It is connected to the top point holder.

The other secondary conductor 18b is sandwiched from the transformer 17 with an insulating plate 21 made of, for example, Bakelite, and the second conductive plate 22 is provided on the upper surface of the first conductive plate 20 in the vicinity of the first flexible plate 20. To the front of the gun arm 8 is provided with a substantially U-shaped second flexible plate 23 made of, for example, an ounce copper plate, which is vertically bent. The first conductive plate 19, the insulating plate 21, and the second conductive plate 2
2 is electrically insulated and fastened by a bolt 24. The first flexible plate 20 and the second flexible plate 23 are
Is made of an ounce copper plate, so it can be bent not only in the vertical direction but also in the horizontal direction.

The present embodiment is constructed as described above and operates as follows. First, after pulling in the piston rod 12a of the pressure cylinder 12 and extending the air cylinder 5 to open the upper electrode 15 and the lower electrode 9,
The work W is loaded between the upper electrode 15 and the lower electrode 9 by being handled by, for example, another robot. Next, the upper electrode 15 is pushed down by the pressure cylinder 12, and at the same time, the gun mounting unit 3 including the gun 6 is pulled upward by the air cylinder 5. At this time, the suspension spring 4 functions to accelerate the initial speed when the gun mounting unit 3 is raised. The work W is the upper electrode 1.
It is sandwiched by the lower electrode 5 and the lower electrode 9 with a slight pressure.

Next, when the clamped material 10 is released by the clamper 11 provided in the gun mounting unit 3 and the clampers 31 and 32 are also wide open and released.
The gun 6 suspended by the gun spring 7 is in a so-called weightless state. Then, when the air pressure of the pressurizing cylinder 12 is increased to the energizing pressure, the piston rod 12
Since the adapter 12b shown in FIG. 3 compresses the pressure spring 16 via a, the work W is strongly sandwiched between the upper electrode 15 and the lower electrode 9. Then, at this time, the posture of the gun 6 automatically changes to the posture in which the upper electrode 15 and the lower electrode 9 hit the welding surface of the work W perpendicularly. That is,
The equalizing operation is performed.

After that, when the upper electrode 15 and the lower electrode 9 are energized, the welding point of the work W is melted by resistance heat. Then, since the pressure spring 16 is compressed as described above, the upper electrode 15 and the lower electrode 9 are connected to the work W.
The work W is strongly pressed so as to bite into the melted welding point, and complete and strong resistance welding is performed on the work W. That is,
Electrode timing delay is prevented, high responsiveness is obtained, and perfect spot welding is performed.

During the energization, as shown in FIGS. 4 and 5, an alternating current is passed from the transformer 17 through the secondary conductor 18 to the upper electrode 15 and the lower electrode 9, but the instantaneous direction of the current flow. Looking at, for example, from the transformer 17 to the secondary conductor 18a
From the first conducting plate 19 and the first flexible plate 20 of the shank 1
5a to the upper electrode 15 and further through the work W to lift the gun arms 8 on both sides from the lower electrode 9 to pass through the second flexible plate 23 and the second conductive plate 22 of the secondary conductor 18b, It flows back to the transformer 17. In addition, the arrow in each figure has shown the said flow direction of an electric current.

Of the above current paths, the first conducting plate 19 and the second conducting plate 19
Since the conductive plates 22 extend in parallel and the current is passed in the opposite direction, as shown in FIG. 6A, it is generated between the first and second conductive plates 19 and 22 based on Faraday's law. The repulsive force acts on each other due to the magnetic lines of force. However, the first conducting plate 1
9. Since the second conductive plate 22 is fastened and fixed by the bolts 24, the repulsive force does not hinder the equalizing operation.

Although the first conducting plate 19 and the first flexible plate 20 are close to the gun arm 8, the current flowing through the first conducting plate 19 and the first flexible plate 20 and the current flowing through the gun arm 8 are different from each other. Since they are orthogonal to each other, repulsive force or attractive force due to magnetic field lines based on Faraday's law does not act. In addition, if the flowing directions of two conductors that are close and parallel to each other are the same,
As shown in FIG. 6B, the attraction force by the magnetic field lines based on Faraday's law works, but there is no such part in this embodiment.

As described above, according to this embodiment, the gun 6
When the clamped material 10 is released from the clamper 11,
Since a so-called weightless state is obtained in which the gun spring 7 hangs down from the ceiling portion 2a of the mounting plate 2 fixed to the main body 1, when the work W is strongly sandwiched between the upper electrode 15 and the lower electrode 9, for example, the work W Even if it includes a three-dimensional shape, it automatically changes to a posture in which it is vertically sandwiched between the upper electrode 15 and the lower electrode 9.

Since there is a three-dimensional equalizing action in this manner, the electrode hits the work vertically even if the electrode is not accurately dressed. Therefore, the conventional welding indentation 25 shown in FIG. 7B is used. As shown in FIG. 7 (a), the welding can be performed cleanly without the welding burrs 26 becoming large and the welding burrs 26 being generated or the welding strains 27 being generated. It is not necessary to correct the welding distortion 27. Therefore,
This has the effect of improving work efficiency.

Further, regarding the secondary conductor from the transformer on the main body side, the first conducting plate 19 and the second conducting plate 2 which are close and parallel to each other are provided.
2 is fixed by bolts, and the direction of the current flowing through the first flexible plate 20 and the first conducting plate 19 of the secondary conductor 18a that is close to the left and right gun arms 8 is orthogonal to the direction of the current flowing through the gun arm 8. Therefore, in any case, the influence of the electromagnetic repulsion force or the attraction force due to the Faraday effect does not affect the gun 6, so that the above-mentioned equalizing action is not hindered. This is effective in stabilizing the above-mentioned improvement in work efficiency.

When the work W is sandwiched between the upper electrode 15 and the lower electrode 9 and is energized, the pressure spring 1
Since 6 presses the upper electrode 15, when the welding point of the work W is melted, the work W is pressed so as to bite strongly from the outside, so that complete and strong resistance welding is performed. That is, since the electrode timing delay is prevented, there is an effect that the reliability of spot welding is improved. It should be noted that the present invention is not limited to the above-described embodiments, but can be implemented in other modes by making appropriate changes.

[0036]

As described above, according to the present invention, the gun having the clamped material at the lower end of the gun arm is hung from the main body by the gun spring, and the gun mounting unit is provided with the clamper for grasping the clamped material. Before releasing the clamped material from the clamper, the gun hangs down by the gun spring, and when the work is clamped between the upper electrode and the lower electrode by the pressure cylinder, each electrode works even if it is a three-dimensional work due to the equalizing action. It is set perpendicular to the welding surface. As a result, the welding indentation after welding is reduced and the occurrence of welding burrs and welding distortion is prevented. Therefore, there is an effect that correction work for these is unnecessary and work efficiency is improved.

Further, by providing a pressurizing unit having a pressurizing spring between the upper electrode and the pressurizing cylinder which presses the upper electrode, the urging force acts during welding, and the timing when the welding point of the work is melted Since the electrode bites in without delay, high responsiveness can be obtained, and welding reliability can be improved.

Regarding the supply of the welding current, a secondary conductor consisting of a conductive plate extending from the main body toward the gun arm and a substantially U-shaped flexible plate which is flexible at the upper and lower sides is used. Are connected at right angles so that electromagnetic repulsion and attraction due to Faraday's law are not generated, and the conductive plates are fixed to each other with an insulator in between, and even if a force due to the Faraday effect is generated, they are displaced. As a result, the three-dimensional equalizing action is smoothly and accurately performed without receiving unnecessary external force, and the above-described improvement in work efficiency is stabilized.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing an embodiment of the present invention.

FIG. 2 is an enlarged view showing details of a gun.

FIG. 3 is a diagram showing details of a pressure unit.

FIG. 4 is a diagram showing a layout of a secondary conductor that supplies a welding current.

FIG. 5 is an explanatory diagram showing a current path of a welding current.

FIG. 6 is a diagram illustrating Faraday's law.

FIG. 7 is a diagram showing a comparison of welding quality with a conventional one.

FIG. 8 is a diagram showing a conventional example.

[Explanation of symbols]

1 body 2 Mounting plate 2a ceiling 3 gun mounted unit 4 suspension springs 5 air cylinders 6 gun 7 gun spring 8 gun arms 9 Lower electrode 10 Clamped material 11 clamper 12 Pressure cylinder 12a piston rod 13 ball splines 14 Pressure unit 15 Upper electrode 15a shank 16 Pressure spring 17 power transformer 18 (18a, 18b) Secondary conductor 19 First guide plate 20 First Flexible Plate 21 Insulation plate 22 Second guide plate 23 Second Flexible Plate 24 Volts 25 Welding impression 26 Weld burr 27 Weld distortion 31, 32 clamper 51 C type spot welding gun device 52 floor panel 52a tunnel section 52b inclined surface 53 wrists 54 bracket 55 Equalizing mechanism 56 Guide rod 57 Central Base 57a Air cylinder 57b spring 58 Lower arm 58a Standing part 59 Lower electrode 60 upper arm 61 Hinge pin 62 Auxiliary arm 63 rotating cylinder 64 upper electrode 65 pressure cylinder 66 C type spot welding gun W work

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Claims (4)

(57) [Claims] 1. A C-type spot welding gun apparatus for supporting an upper electrode and a lower electrode by a C-shaped arm and sandwiching a work between the upper electrode and the lower electrode to weld the workpiece by energizing the workpiece. A gun mounting unit that is hung by a suspension spring and is vertically guided to the main body by a drive means provided between the main body and the gun, and a gun hung from the main body by a gun spring. The gun has a frame-shaped gun arm, and the lower electrode and the material to be clamped are provided at the lower end of the gun arm, and the upper electrode can be moved up and down coaxially with the lower electrode at the upper end of the gun arm. A C-type spot welding gun device, comprising a pressure cylinder attached thereto, and the gun mounting unit being provided with a clamper for grasping the material to be clamped. Place 2. The C-type spot welding gun device according to claim 1, wherein the driving means is an air cylinder. 3. The upper electrode is mounted on the pressure cylinder through a pressure unit guided along the gun arm, and the pressure unit sandwiches a pressure spring to press the upper electrode and the pressure unit. The C-type spot welding gun device according to claim 1 or 2, which is connected to a piston rod of a cylinder. 4. The upper electrode is provided with a first conductive plate extending from the main body toward the gun arm, and a substantially U-shaped upper and lower flexible member provided between a tip of the first conductive plate and the upper electrode. The lower electrode is connected to a power source through a first secondary conductor formed of a first flexible plate, the lower electrode extends from the main body toward the gun arm, a tip of the second conductive plate, and the second conductive plate. An approximately U provided between the gun arm and a position above the first flexible plate.
A second secondary conductor consisting of a second upper and lower flexible plate and a gun arm are connected in sequence to a power source, and the first conductive plate and the second conductive plate are made of an insulating material. The two are fixed to each other by sandwiching them therebetween.
The described C-type spot welding gun device.