JPH09150275A - Resistance welding method for pipe and resistance welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistance welding method for a pipe by which repairing work is easily executed and the defective welded pipe is hardly caused and to provide the apparatus therefor. SOLUTION: A pipe (p) is placed on plural lower electrodes 12a, 12b arranged on an electrode holding table 10 and plural welding positions of the pipe (p) are matched with the positions above respective required lower electrodes 12a, 12b, and after matching a work held to be moved vertically on the pipe (p) with the position above either one of the lower electrodes 12a, (12b), the work is moved downward and brought into contact with the pipe (p) on the lower electrode 12a. Then, the work is resistance-welded to the pipe (p) by conducting the electricity between upper electrodes 70a, 70b connected to the work and the lower electrode 12a, (12b).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding device for resistance-welding a plurality of works to a required portion of a pipe.

[0002]

2. Description of the Related Art For example, as a device for welding a port (work) of a pipe joint to a cylinder pipe, Japanese Patent Publication No. 7-41
As disclosed in Japanese Patent No. 422, a plurality of works are connected to a lower electrode to hold a movable electrode so that various shapes such as a diameter of a cylinder pipe, a pitch size, and an angle can be accommodated. It is arranged on a table, a pipe is mounted on the work, the upper electrode is arranged above, and the movable electrode holding table is moved in the direction in which the lower electrodes are arranged. There is one in which the work is positioned directly below, and further the upper electrode is lowered to energize, and each work is sequentially welded to the pipe.

[0003]

By the way, in the above-mentioned conventional structure, a plurality of works are set on the movable electrode holder in advance, and the setup work is troublesome. Since the work must be supplied every time, the work supply mechanism is complicated and hinders automation.

Further, since the work is connected to the lower electrode and the resistance welding is usually performed while the pipe is supported by the two works, one pipe is melted at the time of welding and the pipe is slightly inclined and the other is welded. However, there was a problem in that the work could not be joined to the pipe in a uniform manner and the defect rate increased.

Furthermore, each work must be precisely aligned with a through hole or the like formed in the pipe in advance, and if the specification of the work mounting position changes even slightly,
There is a problem that it is necessary to reset the position of the lower electrode, which is troublesome.

Further, since each work is connected to the lower electrode, when a current is applied from the upper electrode on a desired work, a part of the current flows into the lower electrode of the work at another location, There is also a problem that welding of the work occurs and the welding quality deteriorates. An object of the present invention is to solve the problems of the conventional configuration.

[0007]

According to the present invention, a pipe is mounted on a plurality of lower electrodes arranged on an electrode holder so that a plurality of welded portions of the pipe are aligned with the lower electrodes. Position the pipe on the pipe, hold the work up and down on the pipe, and move the electrode holder and the work relative to each other to match the work on one of the lower electrodes and then lower the work to lower the electrode. A resistance welding method for a pipe, characterized in that the work is resistance-welded to the pipe by bringing the pipe into contact with the pipe and energizing between an upper electrode and a lower electrode connected to the work.

Further, according to the present invention, as an apparatus for carrying out such a resistance welding method, an electrode holding base having a plurality of lower electrodes on which a pipe is mounted, and a plurality of welding points of the pipe on the electrode holding base are provided. , So that they match on the lower electrode,
A pipe positioning means for positioning the pipe and a work piece which is disposed on the lower electrode so as to be able to move up and down, holds a work to be welded to the pipe in a detachable manner, connects the work piece to the upper electrode to conduct electricity, and at the lower position. The work power feeding holding device for bringing the work into contact with the pipe and the work holding position of the work feeding power holding device are vertically aligned with any of the lower electrodes so that the electrode holding base and the work power feeding holding device are opposed to each other. A resistance welding apparatus for a pipe, comprising electrode moving means for moving and fixing means for fixing a work during welding.

In such a structure, the work is held by the work power feeding and holding device, while the electrode moving means positions the required lower electrode immediately below the work holding position. Here, the electrode moving means may move the electrode holding base with respect to the work power feeding holding device as in the embodiment described later, but by fixing the electrode holding base,
The work power supply holding device may be moved.

For this reason, when the work power supply holding device descends the work, the work comes into contact with the pipe, and a current flows from the upper electrode through the work and the pipe to the lower electrode immediately below the work. Is resistance welded.

In such a structure, the electrode moving means holds the plurality of lower electrodes on which the pipes are mounted so that the lower electrodes can be moved up and down on the movable electrode holder and urged upward. Is configured to be moved in the row direction of the lower electrodes by the front-rear driving device so that any one of the lower electrodes is positioned immediately below the work holding position of the work power feeding holding device, and the work power feeding holding device is also provided. By fixing the lower terminal piece below the movable electrode holder at the position immediately below, and the work is pressed against the pipe from above, the lower electrode is lowered against the upward biasing force, and the work is directly below the work. A configuration in which only the lower electrode of (1) contacts the lower terminal piece can be proposed as a suitable one.

In such a structure, when the work is pressed against the pipe from above, only the lower electrode immediately below the work comes into contact with the lower terminal piece, and for the first time, the upper electrode and the lower electrode are energized. It will be. Therefore, the lower electrode in the other position is maintained in the insulating state, and the current does not flow in, so that the current does not disperse.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a resistance welding apparatus for a pipe p according to the present invention will be described with reference to the accompanying drawings. This pipe p
As shown in FIGS. 1 to 3, the resistance welding apparatus of FIG. 1 moves a movable electrode holding base 10 having a plurality of lower electrodes 12a and 12b on a base 1, and moves the movable electrode holding base 10 to perform welding. An air cylinder (electrode moving device) 7 for positioning the required lower electrodes 12a and 12b at a position I, and a movable electrode holder 10
Above, the lower electrode 12 where the predetermined welding point of the pipe p is required
A pipe positioning device 30 that positions the pipe p so as to be located on the a and 12b, and a pipe fixing device 45 that fixes the work w at the time of welding at a position facing the pipe positioning device 30. Further, the work power supply holding device 60 is provided at the welding position I on the column 2 to which the base 1 is attached. A work w is supplied to the work power supply / holding device 60 by a work supply device 80 provided on the base 1.

Each of the above-mentioned configurations will be sequentially described. The movable electrode holder 10 is moved in the left-right direction of FIG. 1 by an air cylinder 7 mounted on the base 1 via a guide member (not shown) provided on the lower surface of the movable electrode holder 10. Only movable. The air cylinder 7 constitutes an electrode moving device. The movable electrode holder 10
As shown in FIG. 4, the lower electrodes 12a and 12b are
The movable electrode holder 10 is supported along the moving direction, and the air cylinders 7 align the welding electrode I at the welding position I. This positioning is easily controlled by a limit switch or the like. Further, when the positional interval between the holes h and h is changed, it can be easily dealt with by moving and adjusting the position of the limit switch in the left-right direction.

Each of the lower electrodes 12a and 12b has an arcuate contact edge inscribed in the pipe p at its upper edge, and an electrode rod 14 is fixed to the lower surface thereof. Then, the electrode rod 14 is inserted into the support cylinder 15 fixed to the movable electrode holder 10,
The lower electrodes 12a and 12b can be raised and lowered. Also,
A spring 16 for urging the lower electrodes 12a and 12b upward is attached between the brim of the supporting cylinder 15 and the electrode rod 14, and the engaging peripheral edge formed at the lower end of the electrode rod 14 is at the lower edge of the supporting cylinder 15. The contact position is the floating position of the lower electrodes 12a and 12b.

In such a structure, the lower electrodes 12a, 1
The width W of 2b (see FIG. 4) is made sufficiently wide with respect to the diameter of the work w described later. Therefore, even if the position of the hole h of the pipe p is slightly changed due to a change in specifications or the like, as long as it is within the width of the lower electrodes 12a and 12b (there is no problem even if it deviates slightly from the width), the lower electrode 12a, It is not necessary to adjust the position setting of 12b, which facilitates the handling.

On the other hand, at the welding position I on the base 1,
The lower terminal piece 17 is fixed. This lower terminal piece 17
Is grounded via the electric circuit frame 18.
Then, one of the required lower electrodes 12a and 12b is positioned at the welding position I by controlling the movement of the movable electrode holding base 10, and the electrode rod 14 is pressed against the peripheral surface of the pipe p of the work w, which will be described later, to lower the lower terminal. The lower electrode 12a, 12b can be connected to the ground side so as to be in contact with the piece 17.

A holding member 19 for stably supporting the pipe p is disposed between the lower electrodes 12a and 12b, as shown in FIGS. This holding member 19
Guide rods 21 and 21 are inserted into the movable electrode holding base 10 to fix the bifurcated receiving portion 22 on the base plate 20 which can be moved up and down, and the spring 23 urges the base plate 21 upward so that the bifurcated The receiving part 22 can be moved up and down by following the pipe p together with the lower electrodes 12a and 12b.
An upper support piece 24 for sandwiching the above with the receiving portion 22 is provided. This upper support piece 24 is shown in FIGS.
Can be converted to the retracted position that allows the pipe p to be disengaged upward.

On the other hand, on the movable electrode holding base 10, as shown in FIGS. 8 and 9, the pipes h are formed so that the holes h, h formed in advance in the pipe p are located on the required lower electrodes 12a, 12b. A pipe positioning device 30 for positioning p is provided.

That is, the movable electrode holding base 10 is provided with guide rods 31, 31 in the left-right direction, and the guide rods 3 are provided.
A moving body 32 having a transfer cylinder inside is fitted into the units 1 and 31. A support frame 34 provided with a vertical guide piece 33 is mounted on the moving body 32, and an elevating body 36 that is moved up and down by a cylinder 35 is attached to the guide piece 33, and the elevating body 36 is provided with a drawing. A positioning rod piece 37 that projects in the middle right direction is provided. A positioning protrusion 38 that fits into the hole h is provided from the inside of the pipe p at the tip of the positioning rod piece 37. Further, the positioning rod piece 37 comes into contact with the end edge of the pipe p and holds the end portion of the pipe p together with the positioning convex portion 38.
9 (see FIG. 8) is provided. This contact holding piece 39
Is fixed to the positioning rod piece 37 by a screw so as to be movable and adjustable in the longitudinal direction thereof, so that the standard change of the pipe p can be dealt with.

Then, by inserting the positioning projection 38 into the hole h of the pipe p transferred onto the lower electrodes 12a and 12b by the gripping and conveying device 105 described later, the forward and backward positions of the pipe p are stably defined. I am trying.

That is, with the moving body 32 in the retracted position, the pre-positioned pipe p is carried onto the lower electrodes 12a, 12b by the gripping and carrying device 105, and in this state, the moving body 32 is moved forward. The pipe p
By inserting the positioning rod piece 37 from the end of the, the positioning protrusion 38 and the hole h are vertically aligned with each other, the elevating body 36 is raised, and the positioning protrusion 38 is inserted into the hole h.
The pipe p is positioned so that each hole h corresponds to the lower electrodes 12a and 12b in the vertical direction. Then, the lower electrode 12
After the pipe p is sandwiched between the receiving portions 22 and 22 and the upper support piece 24 between a and 12b, the gripping action of the gripping and conveying device 105 is released. The positioning of the pipe p is performed by the hole h
However, the pipe p may be provided with a positioning through hole separately.

After positioning the pipe p in this way, as described above, the air cylinder 7 is driven to move the pipe p together with the pipe positioning device 30 so that the holes h are sequentially positioned at the welding position I.

The pipe p positioned in this way
Is fixed by a pipe fixing device 45 so as not to move during welding.

The structure of the pipe fixing device 45 will be described with reference to FIG. On the right side of FIGS. 1 and 3, a pipe fixing device 45 is mounted on the base 1 at a position substantially facing the pipe positioning device 30 on the left and right. The pipe fixing device 45 is provided with a guide rod 46 in the left-right direction, and a movable body 47 having a transfer cylinder inside is fitted into the guide rod 46. A support frame 49 provided with guide pieces 48, 48 is mounted on the moving body 47, and lifting guides 51, 51 of a lifting body 50 urged upward by a cylinder 52 are attached to the guide pieces 48, 48. To be done. A center holding ring 53 protruding leftward in the drawing is supported by the sheath piece 54 on the elevating body 50. An operating rod 55 fixed to a rod of a cylinder 58 mounted on the elevating body 50 is inserted into the sheath piece 54, and a conical pusher 56 provided at an end of the operating rod 55 is attached to a center holding ring 53. When the cylinder 58 is in the tensioned state, the peripheral edge of the center holding ring 53 is expanded by the action of the pusher 56.

Then, the pipe fixing device 45 moves to the left along the guide rod 46 almost in synchronization with the pipe positioning device 30, and inserts the center holding ring 53 into the center of the pipe p. The center retaining ring 53 is located at the welding position I,
The deformation of the pipe p due to the pressure contact of the work w is prevented.
Then, in this state, by the operation of the cylinder 58,
The operating rod 55 is retracted, the center holding ring 53 is expanded, and the pipe p is fixed inside.

Next, a work power feeding and holding device 60 that feeds a work w to the hole h of the pipe p and welds it, and a work feeding device 80 that feeds the work w to the work power feeding and holding device 60 will be described.

As shown in FIG. 1, an elevating cylinder 61 is attached to the column 2, and a work power supply holding device 60 is attached to the cylinder rod of the elevating cylinder 61. This work power supply holding device 60, as shown in FIGS.
A holding receiving portion 69 for the work w is provided below the mounting plate 62 that is fixed to the cylinder rod, and the movable body 63 is mounted on the guides 64, 64 in the front-rear direction. The attached bite cylinder 66 enables movement in the front-rear direction. The holding portion 69 is the movable body 6.
It is inserted through the through hole formed in 3. Further, a bite cylinder 67 is provided in the rear part of the movable body 63, and a conductive plate 71a is fixed to the front part thereof, and an arcuate bite whose inner end is substantially fitted to the outer peripheral surface of the work w is attached to the conductive plate 71a. The upper electrode 70a having the edge is fixed. Further, the conductive plate 71b is fixed to the cylinder rod of the bite cylinder 67,
An upper electrode 70b in which an arcuate biting edge whose inner end is substantially fitted to the outer peripheral surface of the work w is formed on the conductive plate 71b.
Has been fixed.

When the bite cylinder 66 operates in the rod extension direction, one upper electrode 70a is in the bite position, and when the bite cylinder 67 also operates and the rod extends, the other upper electrode 70b also bites. It is the attachment position, and the work w is sandwiched by the upper electrodes 70a and 70b at this position. The sandwiching position is predetermined so as to be consistent with the welding position I. When each of the cylinders 66 and 67 is switched to the rod contraction position, the upper electrodes 70a and 70b are relatively separated from each other to the open position.

On the other hand, conductive bands 72, 72, which are connected to the conductive plates 71a and 71b and move integrally, are fixed to the left and right positions of the movable body 63 of the mounting plate 62, and the upper electrode Power is supplied to 70a and 70b.

The work w is supplied from the work supply device 80 to the lower surface of the holding portion 69 between the upper electrodes 70a and 70b one by one, and the bite cylinders 66 and 67 are operated in accordance with the supply of the work w. The work w is held between the upper electrodes 70a and 70b.

On the other hand, as shown in FIG. 14, a lifting pin 74, which is biased downward by a cylinder 73 having a weak force, is vertically inserted into the holding portion 69, and the work w is placed on the upper electrode 70.
The lifting pins 74 are inserted into the through holes t of the work w while being supported by the a and 70 b and supported right below the holding receiving portion 69. Therefore, in the case where the work w that has been bitten by the upper electrodes 70a and 70b descends together with the work power feeding and holding device 60 by the elevating cylinder 61 and comes into contact with the surface of the work w, the hole h and the work w are If they do not match, the elevating pin 74 relatively rises. At the proper position, the lower end of the elevating pin 74 is inserted into the hole h of the pipe p, and its ascending operation is not performed. Therefore, by detecting the state of the lifting pin 74 with the proximity switch SW,
It can be detected whether or not the work w exactly matches the hole h of the pipe p. When the lifting pin 74 is inserted into the hole h and the hole is confirmed, the pin 74 is retracted upward by the action of the cylinder 73, and the upper electrode 70 is removed.
Power is supplied to the work w via a and 70b,
The work w will be welded to an appropriate portion of the pipe p.

Next, the construction of the work supply device 80 will be described with reference to FIGS. The work supply device 80 is
The work transfer device 81 shown in FIGS. 14 and 15 and FIGS.
The work transfer device 8 is configured to discharge the works w indicated by 7 one by one.
1 and a work standby device 92 that is handed over to the work piece 1.

A work transfer device 81 according to FIGS.
The configuration of will be described. A mounting plate 82 of the work transfer device 81 is supported on the base 1. A transfer cylinder 83 is provided on the mounting plate 82 in the left-right direction. The mounting plate 8 is attached to the end of the cylinder rod of the transfer cylinder 83.
4 is fixed, and an L-shaped lifting support piece 85 is mounted on the mounting plate 84 so as to be lifted and lowered by a lifting cylinder. A support pin 86 that is inserted into the through hole t of the work w from below is provided at the tip of the lifting support piece 85. on the other hand,
A positioning frame 87 is supported by the mounting plate 82 so as to project in the left-right direction, and a positioning pin 89 is projectingly provided on the mounting plate 84. When the transfer cylinder 83 is driven and the cylinder rod is extended, the positioning frame 87 is moved to the positioning frame 87. The positioning pin 89 is fitted in the formed positioning hole 88 to define the rod extension position.

At the retracted position of the transfer cylinder 83, the support pin 86 coincides with the work discharge port of the work waiting device 92, and as shown by the solid line in FIG. The rod w of the cylinder 83 extends the work w to a position directly below the elevating pin 74 of the holding portion 69, and as the elevating and lowering support piece 85 rises, the work w as well as the support pin 86 rises to the position. Then, the work w is held between the upper electrodes 70a and 70b.
Then, with this clamping, the lifting support piece 85 descends,
The support pin 86 is disengaged from the through hole t of the work w, and further, with the rod contraction of the transfer cylinder 83, the support pin 86 is returned to the standby position that coincides with the discharge port of the work w of the work standby device 92. Become. And on the other hand,
The cylinder 73 is driven, and the lifting pin 74, which was at the upper retracted position, is inserted into the through hole t.

Next, the structure of the work standby device 92 will be described. The mounting plate 82 has a work standby path 94 in the vertical direction.
The work feeding port piece 93 in which is formed is fixed by aligning the support pin 86 at the standby position with the work discharging port at the lower end thereof in the vertical direction. This work feeding port piece 93 is provided with proximity switches 95a and 95b near the delivery position of the work w immediately below the work discharging port, and a solenoid 96 for advancing and retracting the rod end in the work standby path 94, respectively. It is provided. Then, the work w is held in the standby state with the rod of the solenoid 96 protruding into the work standby path 94. Further, when the support pin 86 is located at the work discharge port, the proximity switch 95b at the lower portion detects it, the solenoid 96 is driven and the work w drops, and the support pin 86 is inserted into the through hole t. The proximity switch 9 indicates that the work w is supported by the support pin 86.
5a, and accordingly, the rod extension drive of the transfer cylinder 83 is performed as described above.

A supply tube 9 is provided in the work standby path 94.
9 are connected, and the works w aligned in the same direction by the parts feeder 98 shown in FIG. 1 are transferred by the supply tube 99.

Next, the supply mechanism of the pipe p will be described.
As shown in FIG. 19, on the base 1, a position setting device 100 for positioning the hole h of the pipe p at a position directly above is provided near the welding position of the pipe p. This position setting device 10
0 positions the pipe p at a fixed position in the lengthwise direction, and the upper rotating roll 101 and the idle rolls 102, 1
When it is rotated while being held by 02, and the hole h comes directly above, the positioning pin 103 is inserted into the hole h, and the rotation of the rotation roll 101 is stopped and positioned at that position. . Then, the pipe p thus positioned is gripped by the gripping and conveying device 105 having the sandwiching claws 106, 106 shown in FIG.
a, 12b. Thus, this lower electrode 12
The pipes p on a and 12b have the holes h directly above, and the longitudinal direction thereof is always at a fixed position. By inserting the positioning protrusions 38 into the holes h, the pipes p are respectively connected to the lower electrodes 12a, 12b. It is positioned so as to correspond to 12b above and below.

Next, a series of welding processing steps according to each of the above-mentioned configurations will be described. As described above, the position of the pipe p is set by the position setting device 100 so that the hole h is directly above,
It is transferred by the gripping and conveying device 105 onto the lower electrodes 12a and 12b on the movable electrode holder 10 and the holding member 19.
Then, while maintaining the state of being supported by the gripping and conveying device 105, the positioning rod piece 37 is inserted from one end of the pipe p by the movement of the moving body 32, the lifting body 36 is raised, and the positioning convex portion is formed in the hole h. By inserting 38,
The pipe p is positioned so that each hole h corresponds to the lower electrodes 12a and 12b in the vertical direction. Then, the lower electrode 12
After holding the pipe p between the receiving portions 22 and 22 and the upper support piece 24 between a and 12b, the gripping action of the pipe p by the gripping and conveying device 105 is released, and the positioning convex portion 38 is
It descends, retreats, and retracts outside the pipe.

Positioning the pipe p in this way,
In synchronization with this, the guide piece 48 is driven, the pipe fixing device 45 moves to the left along the guide rod 46 almost in synchronization with the pipe positioning device 30, and the center holding ring 53 is inserted into the center of the pipe p. To be done. Then, by the operation of the cylinder 58, the operating rod 55 is retracted, the center holding ring 53 is expanded, and the pipe p is fixed inside.

As a result, the pipe p is stably held and each hole h is set at the welding position I.

Then, the lifting cylinder 61 is driven,
The work w is previously supplied by the work supply device 80, and the work power supply holding device 60 holding the work w between the upper electrodes 70a and 70b descends. With this lowering, the work w coincides with the hole h. If they do not match due to a position error or the like, the protruding end of the lifting pin 74 inserted into the work w is not inserted into the through hole t of the work w,
The work power supply holding device 60 rises and welding is not performed. When the hole h and the work w coincide with each other, the lifting pin 74
After the evacuation is performed, the pipe w is pressed from above by the work w by driving the elevating cylinder 61.

Therefore, one of the lower electrodes 12a and 12b descends against the ridge 16, and the lower surface of the lower electrode 12a immediately below the work w comes into contact with the lower terminal piece 17. Thus, a current flows from the upper electrodes 70a and 70b to the lower electrode 12a via the work w and the pipe p, and the work w
Is subjected to resistance welding and solidified to the pipe p.
At this time, even if the work w is melted by the resistance welding, there is no problem because the work w is pressed against the pipe p by the elevating cylinder 61. The other lower electrode 12b (12a) is not in contact with the lower terminal piece 17 and is maintained in an insulated state. For this reason, the current is not dispersed and the resistance welding can be efficiently performed.

Next, the holding of the pipe p by the pipe fixing device 45 is released, the air cylinder 7 is driven, another work w is re-supplied to the upper electrodes 70a and 70b, and the hole h on the lower electrode 12b is opened. It is set to the welding descending position, and another work w is re-supplied to the upper electrodes 70a and 70b,
When the work power feeding / holding device 60 descends and the pipe p is pressed against the work w, the lower surface of the lower electrode 12b comes into contact with the lower terminal piece 17, and resistance welding of the work w is performed again.

Then, the work w is joined to the holes h and h of the pipe p. Then, the air cylinder 7 is driven in the rod contracting direction, the movable electrode holder 10 returns to the left side, the gripping and conveying device 105 grips the work w, and in this state, the receiving portions 22, 22 and the upper supporting piece 24. The pinching by the pipe is released, and the pipe p
Is transported to a predetermined position. After this, the pipe p is subjected to a demagnetizing device for removing the excitation during transportation.

In the description of such an embodiment, a uniform pipe p having the same diameter in the longitudinal direction was used. However, in the case of different diameter pipes having different diameters in the longitudinal direction,
This can be easily dealt with by changing the height of the lower electrodes 12a and 12b and the diameter of the arcuate contact edge. Therefore, the above-mentioned configuration, the size of the pipe diameter, pitch dimensions, angling, etc.
It can be welded into a wide variety of shapes.

[0047]

As described above, the present invention mounts a pipe on a plurality of lower electrodes arranged on an electrode holder,
A plurality of welding points of the pipe are respectively aligned with a required lower electrode, and a work held so as to be vertically movable on the pipe is aligned with a required lower electrode, and then the work is lowered to obtain the required lower electrode. Since it relates to a method for performing resistance welding of the work to the pipe by bringing the upper electrode connected to the work into contact with the pipe above and the lower electrode, and a device for performing the method, Since it is not necessary to previously set a plurality of works on the movable electrode holder together with the lower electrode at a required interval, setup work is easy, and a single work supply mechanism can be used. Suitable for automation.

Further, since the work is welded from above the pipe, the welded state does not change the holding state of the pipe, and the work piece can be easily pressure-welded to cope with the melted state and the defective rate. Is small.

Furthermore, it is not necessary to strictly set the relationship between each lower electrode and the position of the work in the longitudinal direction only by setting the lower electrode to be wide with respect to the work. Also in the case of changing the above, it is not necessary to reset the lower electrode position, and the above-mentioned setup work can be further facilitated.

Further, by fixing the lower terminal piece further below the movable electrode holder and pressing the workpiece against the pipe from above, the lower electrode descends, and only the lower electrode directly below the workpiece is lowered. In the structure in which the lower terminal piece is brought into contact with the lower terminal piece, the insulation of the other lower electrodes can be maintained, the electric current can be dispersed, and unnecessary welding at other locations can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view of a resistance welding apparatus according to the present invention.

FIG. 2 is a side view of the resistance welding apparatus according to the present invention.

FIG. 3 is a front view of a main part of the resistance welding device according to the present invention.

FIG. 4 is a front view of lower electrodes 12a and 12b.

FIG. 5 is a vertical sectional side view of a lower electrode 12a (12b).

FIG. 6 is a front view of a holding member 19.

FIG. 7 is a side view of a holding member 19.

8 is a partially cutaway front view of the pipe positioning device 30. FIG.

9 is a plan view of the pipe positioning device 30. FIG.

10 is a partially cutaway front view of the pipe fixing device 45. FIG.

11 is a front view of the work power feeding and holding device 60. FIG.

FIG. 12 is a side view of the work power supply holding device 60.

13 is a bottom view of the work power feeding and holding device 60. FIG.

FIG. 14 is an enlarged vertical sectional side view showing a grip portion of a work.

15 is a front view of the work transfer device 81. FIG.

16 is a plan view of the work transfer device 81. FIG.

17 is an enlarged plan view of the work standby device 92. FIG.

FIG. 18 is an enlarged vertical side view of the work standby device 92.

FIG. 19 is a left side view of the position setting device 100.

20 is a front view of the gripping and conveying device 105. FIG.

[Explanation of symbols]

 1 Base 7 Air Cylinder 10 Movable Electrode Holder 12a, 12b Lower Electrode 16 Spring 17 Lower Terminal Piece 19 Holding Member 30 Pipe Positioning Device 37 Positioning Rod Piece 45 Pipe Fixing Device 60 Work Power Supply Holding Device 61 Lifting Cylinder 66, 67 Bites Cylinder 70a, 70b Upper electrode 80 Work supply device 81 Work transfer device 92 Work standby device 101 Position setting device 105 Grasping and conveying device p Pipe h hole w Work t through hole

Claims (3)

[Claims] 1. A pipe is mounted on a plurality of lower electrodes arranged on an electrode holder, and the pipe is positioned so that a plurality of welding points of the pipe are respectively aligned with the lower electrode. It is held so that it can be moved up and down, and the electrode holder and the workpiece are moved relative to each other so that the workpiece is aligned with one of the lower electrodes, and then the workpiece is lowered and brought into contact with the pipe on the lower electrode. A resistance welding method for a pipe, wherein the work is resistance-welded to the pipe by energizing an upper electrode connected to the work and a lower electrode. 2. An electrode holder having a plurality of lower electrodes on which the pipe is mounted, and the pipe is positioned on the electrode holder so that a plurality of welded portions of the pipe are aligned with the lower electrodes, respectively. The pipe positioning means and the lower electrode are provided so as to be able to move up and down, hold a work to be welded to the pipe in a detachable manner, connect the upper electrode to the work to energize the work, and pipe the work in the lowered position. Electrode movement for relatively moving the electrode holder and the work power supply holding device so that the work power supply holding device to be brought into contact with the work power supply holding device is vertically aligned with any one of the lower electrodes. A resistance welding device for pipes, which is provided with a means and a fixing means for fixing a work during welding. 3. The electrode moving means holds a plurality of lower electrodes on which pipes are mounted on a movable electrode holder so that the lower electrodes can be moved up and down and urged upward, and the movable electrode holder is moved forward and backward. Thus, the lower electrode is moved in the direction in which the lower electrodes are arranged, and one of the lower electrodes is configured to be positioned directly below the work holding position of the work power feeding holding device, and at the position immediately below the work power feeding holding device. By fixing the lower terminal piece further below the movable electrode holder and pressing the work against the pipe from above, the lower electrode is lowered against the upward biasing force, and only the lower electrode immediately below the work is The resistance welding apparatus according to claim 2, wherein the lower terminal piece is in contact with the lower terminal piece.