JPH11170064A - Welding equipment of nut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an equipment of carrying out projection welding for plural kinds of welding nut continuously on a panel or the like. SOLUTION: The equipment is constituted of an upper electrode 24 capable of vertical movement only, plural lower electrodes 29-1, 29-2, 29-3 which are fixedly aligned on the lower electrode moving member 28 supported movably on a table 26 and which are equipped with a guide pin 28, and a multilevel cylinder mechanism 34, 35 that shifts movable members so that each lower electrode is temporarily fixed on the extension of the axial center of the upper electrode at the time of welding; numerous kinds of nuts with different diameters can be welded continuously by one equipment and one operator without changing the lower electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for welding a nut, particularly a nut used when continuously projecting a plurality of types of welding nuts to a panel or the like.

[0002]

2. Description of the Related Art In the case of projection welding of the above-mentioned welding nut to a panel or the like, a welding machine as shown in FIG. 14 is generally used. That is, the welding machine is provided with a table 2 protruding forward from the middle stage of the welding machine main body 1.
, The lower electrode 4 is held via a jig 3 supported in an electrically insulated state, connected to a power source by a conductive material 5, and the tip of an arm 6 projected forward from the upper end of the welding machine body 1. A cylinder mechanism 7 equipped with a jig 8 is vertically mounted, an upper electrode 9 is supported on the jig 8 on a concentric axis with the lower electrode 4, and a body 10 is grounded by a conductive material 10.

[0003] When projection welding is performed by such a welding machine, a predetermined welding position of a member to be welded (not shown) such as a panel is positioned on the axis of the upper and lower electrodes 4 and 9. A predetermined welding nut (not shown) is placed on the upper electrode 9 and the upper electrode 9 is lowered by operating the cylinder mechanism 7, and the welding nut and the panel and the like are strongly pressed between the upper and lower electrodes 4 and 9. Pass a large current,
The nut is welded to a panel or the like.

By the way, several kinds of welding nuts having different screw diameters (hereinafter referred to as different diameter nuts) are usually used for the panel and the like. For example, when three kinds of M6, M8 and M10 are continuously welded. Performed the operations shown in FIG. That is, the work shown in FIGS.
Welding machines 11, 12, and 13 for specially welding the different diameter nuts of M6, M8, and M10 are arranged in a straight line at regular intervals. First, the M6 nut is attached to the unprocessed panel W by the M6.
Welded with use welder 11, to the reservoir an intermediate workpiece S ₁ with a welded nut M6 to the middle of the M6 for welder 11 and M8 for welder 12.

[0005] In M8 for welder 12, to which is welded a nut M8 pick up the intermediate workpiece S _1, welding M6, M8 of welded intermediate workpiece S ₂ nuts and M8 for welder 12 M10 It is stored in the middle of the machine 13. In M10 for welder 13, to which is welded a nut M10 pick up the intermediate workpiece S _2, working at M6, M8 and finished products K nuts welded of M10 outside of M10 for welder 13 Complete. In this case, if the number of welding nuts M6, M8, and M10 to the panel and the like is balanced to some extent, as shown in FIG.
1, 12, and 13. For example, when the number of welds of M8 and M10 is smaller than that of the nut of M6, FIG.
The worker A is arranged on the M6 welding machine 11 as shown in FIG.
The welding machines 12 and 13 for M8 and M10 are arranged so that the worker B can carry both machines.

Although there are many types of different diameter nuts, for example, three types, when the number of welds is small, as shown in FIG.
The welding machines 11, 12, and 13 for M8 and M10 are arranged in a fan shape, and one worker A operates all the welding machines 11, 12, and 13 near the key position of the fan, and Welding machine W for M6, M8, M10
There is also a method in which the finished product K is formed by multiplying 2 and 13 one after another. In addition to the above, a method to be referred to as “general-purpose machine”, that is, the lower electrode of one welding machine is prepared for the different diameter nut to be welded, and the lower electrode is replaced according to the different diameter nut. There are ways.

However, the welding methods shown in FIGS. 15, 16 and 17 each require a welding machine for welding nuts of different diameters, which not only increases the equipment cost, but also increases the cost. In the welding method shown, intermediate processed products S ₁ and S ₂ are generated, so that it is not a complete continuous operation, and a space for placing the intermediate processed products S ₁ and S ₂ is required.
Since the welding numbers of the nuts of M8 and M10 cannot be completely balanced, there is a possibility that the work may be uneven. In the welding method shown in FIG.
Even though 2 and 13 are arranged in a fan shape, the walking distance of the worker A becomes considerably long, which not only places a heavy burden on the worker but also makes it difficult to cope with an increase in the required number of weldings. In addition, the method using the “general-purpose machine” also generates an intermediate product, and it takes time to replace (change the setup) of the lower electrode, thereby increasing the work cost.

Therefore, as disclosed in, for example, JP-A-4-200983, A. On a bed fixed to the lower support member of the welding machine as described above, a base connected to a rod of one air cylinder is slidably mounted in a depth direction so as to pass directly below the upper electrode, and is mounted on the base. The two electrode holders are fixed at intervals substantially equal to the length of the rod of the air cylinder, and the two electrode holders are provided with lower electrodes for welding nuts having different diameters, respectively.
A base connected to a rod of a first air cylinder is slidably mounted in the depth direction so as to pass directly below the upper electrode on the bed, and a rack is provided at a tip of the base with a second air cylinder. An electrode supporting portion having a plurality of surfaces which rotates on a vertical surface parallel to the bed via a pinion is provided, and a lower electrode for a welding nut having a different diameter is provided on each of the plurality of surfaces.

However, since the base is moved by only one air cylinder in both A and B, the position is limited to two positions of extension and contraction of the rod, and is the lower electrode limited to two types as in A? Or B, the structure in which the electrode holding portion is rotated by a separate air cylinder through a rack and a pinion on a vertical plane parallel to the bed needs to take complicated means. In the case of B, the lower electrode holder is pushed directly below the upper electrode by the first cylinder via the base, and then the lower electrode holder is rotated by the cylinder of the base 2 via the rack and the pinion, so that A double operation of selecting the lower electrode is required.

[0010]

Therefore, the problem to be solved by the present invention is that a single welding machine and a single operator cannot use a large number of different-diameter welding nuts up to a considerable number of welds. The present invention provides an easy-to-use nut welding device which can be welded to a predetermined portion of a member to be welded continuously without requiring replacement of a lower electrode without requiring a simple operation. It is in.

[0011]

In order to solve the above-mentioned problems, a welding apparatus according to the present invention comprises an upper electrode supported on the upper part of the machine and capable of only moving up and down, and a lower electrode supported movably on a table protruding from the machine. A plurality of lower electrodes provided with guide pins fixed in a row on a moving member, and the lower electrode moving member are moved so that each lower electrode can be temporarily fixed on an extension of the axis of the upper electrode during welding. A second invention in which a protective cover for covering a lower electrode other than the lower electrode facing the upper electrode during welding is added to the first invention and the first invention constituted by a multi-stage cylinder mechanism, and the first invention. And a control mechanism for moving the moving member in accordance with a welding order of the nuts.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS. The one shown in FIGS. 1 and 4 moves the lower electrode linearly so that it is suitable for welding several different diameter welding nuts almost linearly to a relatively narrow and longitudinally long workpiece. In the welding device, a cylinder mechanism 23 having a jig 22 is vertically attached to a tip of an arm (not shown) protruding forward from near the upper end of a machine base 21 of the welding device. The upper electrode 24 is supported by the fixture 22, and the body is grounded by the conductive material 25.

Reference numeral 26 denotes a table projecting forward from the middle of the machine base 21. A long guide member 27 having stoppers 27a formed at both ends is fixed on the table 26, and slides on the guide member 27. Freely long slide member 2
8, a plurality of lower electrodes 29 are fixed on the slide member 28 in a state of being electrically insulated. The lower electrode 2
Reference numeral 9 denotes a plurality of different-diameter nuts, for example, electrodes 29-1, 29-2, and 29-3 for M6, M8, and M10 at appropriate intervals on a straight line passing through an extension of the axis of the upper electrode 24,
It is fixed on the long slide member 28.

Reference numeral 30 denotes a cylinder mechanism for moving the long slide member 28. The cylinder mechanism 30
6, a short guide member 3 provided on the machine base 21 side in parallel with the long guide member 27 and having stoppers 31a formed at both ends.
1, a short slide member 32 that slides over the short guide member 31, and a rod 34 a fixed on the slide member 32, and a rod 34 a connected to the long slide member 2 by a connecting member 33.
A first cylinder 34 connected to the table 8 and the table 26;
Is fixed to the short slide member 3
And a second cylinder 35 connected to the second cylinder 35.

Numerals 36-1, 36-2, and 36-3 are nut supply nozzles for supplying the welding nuts M6, M8, and M10 to the lower electrode.
36-3 are guide pins 38 of the lower electrode (29-2 in the figure) whose tips are opposed to the upper electrode 24 at the time of welding.
It faces upward and is connected to the nut feeder 37. The guide pin 38 is, for example, the one shown by 38-1 in FIG. 9 and has welding nuts M6, M8, M10 and M12.
The body 38-1a has a diameter for fitting a pilot hole such as a panel P to which M12 is welded, but the tip 38-1b extending from the body 38-1a has a welding nut M6. , M8, M10, and a conical shape having a slope of 1/4 to 1/5 in consideration of the pilot hole diameter of the panel P or the like for welding them (other than the pilot hole diameter of the panel for welding M12). is there.

The guide pins indicated by 38-2 in FIGS. 10 and 11 can be used for, for example, welding nuts M6 and M8, and the body 38-2a is fitted with a pilot hole such as a panel P for welding M8. In addition to the diameter, above (on the tip side)
A step portion 38-2c having a diameter smaller than that of the body portion 38-2a through the frusto-conical portion 38-2b and having a diameter in which a pilot hole such as a panel P to which M6 is welded is formed. -2c is a conical tip 38-2d such that M6 is fitted at the tip.

The guide pins 38-1 and 38-2 are shown in FIG.
0, as shown in FIG.
9, for example, when the guide pin 38-2 is used for the welding nut M6, as shown in FIG.
The panel or the like P is located at the step 38-2c,
After fitting the M6 welding nut N1 to the distal end portion 38-2d, the upper electrode 24 is pressed and welded by the pressing tool 41. When the guide pin 38-2 is used for the welding nut M8, a panel or the like P is attached to the upper end of the body 38-2a by using a slightly thinner 42 for the tightening nut of the holder 39 as shown in FIG. Then, an M8 welding nut N2 is fitted over the base ends of the frusto-conical portion 38-2b, the stepped portion 38-2c, and the distal end portion 38-2d, and then pressed by the pressing tool 41 of the upper electrode 24. Weld it.

Although the guide pin 38-3 shown in FIG. 12 is used only for the welding nut N3 having a fixed screw diameter, it is suitable for a welding device using a protective cover which will be described later. The rear end of the body 38-3a is spring 43
The tip 38-3b is made to protrude upward, and as shown in FIG.
-3a, a predetermined welding nut N3 is attached to the tip 3
8-3b, and pressed and welded by the pressing tool 41 of the upper electrode 24. In FIGS. 1 and 2, reference numeral 44 denotes an electrically conductive material, the tip of which is connected to the lower electrode 29, and the base of which is connected to a welding power source (not shown).

When welding the different-diameter welding nuts M8, M6 and M10 to a panel or the like in this order by the welding apparatus of the present invention shown in FIGS. 1 and 2, first, the rod 34a of the first cylinder 34 is reduced in size. , The second cylinder 35
The rod 35a is extended to bring it to the state shown in FIGS. Thereby, the long slide member 28 slides on the guide member 27, and the lower electrode 29-2 for the welding nut M8 is located immediately below the upper electrode 24. Here, a member to be welded, for example, a panel is placed on the lower electrode 29-2, and a pilot hole around which a welding nut M8 is to be welded is fitted to the guide pin 38 on the lower electrode 29-2. The nut is supplied from the nut feeder 37 via the nozzle 36-2. When the supplied M8 welding nut is set at a predetermined position by the guide pin 38, the upper electrode 24 is lowered by the cylinder mechanism 23, and as shown in FIG.
Between the panel P and the welding nut (M)
8) N is clamped and the M8 nut N is pressed against the panel P. In this state, a welding current is passed between the upper and lower electrodes 24 and 29-2, and the welding nut N is welded to the panel P. When the welding is completed, the upper electrode 24 is raised by the cylinder mechanism 23, and the process proceeds to welding of the next M6 welding nut.

When welding the M6 welding nut, with the rod 34a of the first cylinder 34 reduced,
The rod 35a of the second cylinder 35 also contracts. As a result, the long slide member 28 slides on the guide member 27 to the end on the machine base 21 side, and the lower electrode 29-1 for the welding nut M6 is located immediately below the upper electrode 24. Here, similarly to the above, the welding nut M6
The guide pin 3 on the lower electrode 29-1
8, and in this state, the M6 welding nut is supplied from the nut feeder 37 via the nozzle 36-1. When the supplied M6 welding nut is set at a predetermined position by the guide pin 38, the upper electrode 24 is lowered, and the panel P and the M6 nut N are sandwiched between the upper electrode 24 and the lower electrode 29-1 as described above. And attach M6 nut N to panel P
To the upper and lower electrodes 24 and 29 in this state.
−1, a welding current is applied, and the M6 nut N is welded to the panel P. When welding is completed, the upper electrode 24 is raised by the cylinder mechanism 23, and the process proceeds to welding of the next M10 welding nut.

When welding the M10 welding nut, the rod 34a of the first cylinder 34 and the rod 35a of the second cylinder 35 are both extended. As a result, the long slide member 28 slides on the guide member 27 to the distal end of the table 26 in the member 27,
The lower electrode 29-3 for the welding nut M10 is the upper electrode 24
It is located directly below. Here, similarly to the above, the pilot hole to which the welding nut M10 is to be welded to the periphery of the panel is fitted to the guide pin 38 on the lower electrode 29-3.
From the nut feeder 37 to the nozzle 36-
3 and welded as before.

When a control mechanism is provided in the welding apparatus of the present invention having the above-described configuration, the selection state of the lower electrode, the setting state of the member to be welded, and the like are detected in accordance with a predetermined program, and the respective detection signals are used. It can supply necessary kinds of welding nuts, lower and raise the upper electrode, supply and cut off welding current, and the like. This will be described with reference to the flowchart shown in FIG. 13. In step S1, the first and second cylinders 34 and 35 are instructed to select a predetermined lower electrode, for example, 29-2 so that the lower electrode is located immediately below the upper electrode 24. At the same time, it is checked whether or not this is correct. If it is correct, the member to be welded is set on the lower electrode 29-2, and it is checked whether or not this is set correctly (step S2). Next step S3
Is instructed to supply an M8 welding nut having a required diameter from the nut feeder 37 to the guide pin 38 via the nozzle 36-2. Here, the upper electrode 24 is lowered to press the welding nut (step S4), and the current is supplied (step S5). After a certain time, the upper electrode 24 is raised and stopped (step S6).

Here, it is checked whether or not the work is completed as compared with the program (step S7). If NO, the process returns to step S1 to proceed to the next process of the program, and a predetermined lower electrode, for example, 29- The first and second cylinders 34 and 35 are instructed so as to select No. 1 so as to come directly under the upper electrode 24. At the same time, it is checked whether this is correct or not. Is set on the lower electrode 29-2, and it is checked whether or not this is set correctly (step S2). If it is set correctly, the M6 welding nut having a required diameter is set in the nozzle feeder 37 from the nut feeder 37 in the next step S3. It is instructed to supply to the guide pin 38 via 36-1. Here, the upper electrode 24 is lowered to press the welding nut (Step S).
4), energize (step S5). After a certain time, the upper electrode 24 is raised and stopped (step S6). Here, it is checked whether or not the work is completed as compared with the program (step S7). If NO, the process returns to step S1, and the same steps as described above for welding the M10 welding nut again are performed.

The basic structure of the welding apparatus of the present invention shown in FIGS. 3 and 4 is the same as that shown in FIGS. 1 and 2, but the lower electrode (29-2 in the example of FIGS. 3 and 4) used for welding. 4), a protective cover 45 made of, for example, plastic is provided to cover the lower electrodes 29-1 and 29-3. The cover 45 has, for example, a corner so that the lower electrode 29-2 is exposed as shown in FIG. A hole 45a is formed, and its four corners are supported on the table 26 by four columnar members 47 with springs 46 interposed therebetween. By the protective cover 45, the panel P
Unnecessary hits and energization can be prevented.
When the protective cover 45 is used, the guide pin 38-3 shown in FIG. 12 is used as the guide pin 38, and the guide pin 38-3 described above is used. Since it is pulled into the holder 39 of the lower electrode 29 against the spring 43, there is no problem.

The welding apparatus of the present invention shown in FIG. 5 and FIG. 6 is a member to be welded which is generally square and has a relatively small area, but has a stepped shape, and several different-diameter welding nuts are scattered. A plurality of (three in FIG. 5 and FIG. 6) lower electrodes are arranged on a circle so as to rotate on a vertical plane perpendicular to the table so as to be suitable for welding. The horizontal axis 50 is supported by a support plate 49 in the support box 48 and a lid 48a of the support box 48 via an insulator 51 or the like, and the outer end of the horizontal axis 50 is outside the support box 48. And the lower electrode support board 52 is attached, and on the periphery of the support board 52, on the extension of the axis of the upper electrode 24,
And a plurality of lower electrodes 29 provided with guide pins 38 at equal angles on the circumference of a vertical plane perpendicular to the table 26, that is, a plurality of different-diameter nuts, for example, electrodes 29-1 for M6, M8, M10, 29-2 and 29-3 are arranged in a line.

The lower electrode support board 50 is provided with an arm 53, and the arm 53 is connected to the cylinder mechanism 30 as shown in FIGS. Further, a plurality of projections 55-1, 55-2, 55-3 corresponding to the lower electrodes 29-1, 29-2, and 29-3 are fixed to the horizontal axis 50 in the support box 48. An electric conductor / rotation stopper 56 that selectively engages with the plurality of protrusions 55-1, 55-2, and 55-3 is provided.

When the welding nut is welded to a panel or the like by the welding apparatus of the present invention shown in FIGS. 5 and 6, first, the conductor / rotation stopper 56 is firstly moved to the projections 55-1, 55-55.
2, 55-3, and in this state, the first cylinder 34 and the second cylinder 35 are operated, and the horizontal axis 50 is rotated via the arm 53 by the link rod 54, and the predetermined lower electrode For example, when 29-2 is located immediately below the upper electrode (not shown), the conductor / rotation stopper 56 is engaged with the projection, for example, 55-2. Thereafter, as in the welding apparatus shown in FIGS. 1 and 2, the member to be welded is placed on the lower electrode, and a pilot hole around which a predetermined welding nut is to be welded is fitted to the guide pin 38. Remove the nut from the nut feeder 37 to the nozzle 36
After being set at a predetermined position by the guide pin 38, the upper electrode is lowered, and the member to be welded and the welding nut are clamped and pressed between the upper electrode and the lower electrode.
In this state, a welding current is applied to weld the welding nut. When welding is completed, the upper electrode is raised, and the process proceeds to welding of the next welding nut. When welding the next welding nut, the procedure may be performed in the same manner as described above.

The basic structure of the welding apparatus of the present invention shown in FIGS. 7 and 8 is the same as that shown in FIGS. 5 and 6, but the lower electrode (29-2 in the example of FIGS. 7 and 8) used for welding. 4), for example, a protective cover 57 made of plastic is provided to cover the lower electrodes 29-1 and 29-3, and the cover 57 has, for example, a valley so that the lower electrode 29-2 is exposed as shown in FIG. A notch 57a is formed, and four corners of the notch 57a are sandwiched between springs 58 by four columnar members 59.
6 is supported. With the protective cover 57,
Unnecessary hits and energization of the panel P are prevented. When the protective cover 57 is used, the guide pins 38 shown in FIG.
If 8-3 is used, the guide pin 38-3 is pulled into the holder 39 of the lower electrode 29 against the spring 43 even when pressed by the protective cover 57 when not necessary, so that there is no problem.

[0029]

According to the present invention, the nut welding apparatus is fixed in a row on an upper electrode supported only on the upper part of the machine base and capable of only moving up and down, and a lower electrode moving member movably supported on a table protruding from the machine base. Further, a plurality of lower electrodes provided with guide pins, and a multi-stage cylinder mechanism for moving the lower electrode moving member so that each lower electrode can be temporarily fixed on an extension of the axis of the upper electrode at the time of welding. The first invention, the second invention in which a protective cover for covering a lower electrode other than the lower electrode facing the upper electrode at the time of welding is added to the first invention, and the moving member is welded to a nut in the first invention. According to the third aspect of the present invention, which has a control mechanism for moving the parts in order, the first aspect of the invention can provide a welding device having a simple structure and easy to use. A single device and a single operator can easily handle a large number of welds with a simple operation.Furthermore, without replacing the lower electrode, a predetermined nut can be installed at a predetermined position on the member to be welded. Since welding can be performed continuously and there is almost no moving distance of the operator, there is an effect that the working efficiency can be much higher than the conventional one.

Further, according to the second aspect of the present invention, unnecessary energization of the member to be welded and occurrence of a hit are prevented beforehand, and the safety and quality of work can be improved. Further, according to the third aspect of the invention, there is an effect that at least the important work of moving the moving member in accordance with the welding order of the nut can be automated. In addition, according to the present invention, since different kinds of nuts of different diameters can be continuously welded, the quality is stable, and no intermediate processed product is produced, so that there is also an effect of reducing the cost of parts management and process management.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a nut welding device of the present invention.

FIG. 2 is a plan view showing a first embodiment of the nut welding device of the present invention.

FIG. 3 is a front view showing a second embodiment of the nut welding device of the present invention.

FIG. 4 is a plan view showing a second embodiment of the nut welding device of the present invention.

FIG. 5 is a front view showing a third embodiment of the nut welding device of the present invention.

FIG. 6 is a plan view showing a third embodiment of the nut welding device of the present invention.

FIG. 7 is a front view showing a fourth embodiment of the nut welding device of the present invention.

FIG. 8 is a plan view showing a fourth embodiment of the nut welding device of the present invention.

FIG. 9 is a front view showing an example of a guide pin used in the present invention.

FIG. 10 is a cross-sectional view showing a state in which a holder incorporating another example of a guide pin used in the present invention is set on a lower electrode and is thereby welded.

11 is a sectional view showing a state in which the guide pin shown in FIG. 10 is used for welding another different diameter nut.

FIG. 12 is a cross-sectional view showing a state in which a holder incorporating a further example of a guide pin used in the present invention is set on a lower electrode and is thereby welded.

FIG. 13 is a flowchart of a nut welding apparatus of the present invention including a control mechanism.

FIG. 14 is a front view of a commonly used spot or projection welding machine.

FIG. 15 is a schematic diagram showing an example of a procedure for welding different diameter nuts using a plurality of welding machines shown in FIG. 14;

FIG. 16 is a schematic diagram showing another example of a procedure for welding different diameter nuts using a plurality of welding machines shown in FIG. 14;

FIG. 17 is a schematic view showing still another example of a procedure for welding different diameter nuts using a plurality of the welding machines shown in FIG. 14;

[Explanation of symbols]

1 Welding machine main body 2, 26 Table 3, 8, 2
2 jig 4, 29 lower electrode 5, 10, 25, 44 conductive material 6, 53 arm 7, 23, 30 cylinder mechanism 9, 24 upper electrode 11, 12, 13 welding machine
21 Machine stand 27 Long guide member 28 Long slide member 31
Short guide member 32 Short slide member 33 Connecting member 34
First cylinder 35 Second cylinder 36 Nozzle 37 Nut feeder 38 Guide pin 39 Holder 40, 42 Tightening nut 41 Presser 43, 46, 58 Spring 45, 5
7 protective cover 47,59 pillars 48 supporting box 49 supporting plate 50 the horizontal axis 51 insulator 52 lower electrode support plate 54 link rod 55 projection 56 conductors and the rotation stopper W blanks S _1, S ₂ intermediate workpiece K completed Products A, B, C
worker.

Claims (5)

[Claims] An upper electrode supported on the upper part of the machine and capable of only moving up and down, and a plurality of guide pins fixed in a row on a lower electrode moving member movably supported on a table protruding from the machine. The lower electrode, the lower electrode moving member,
A nut welding device, comprising: a multi-stage cylinder mechanism for moving each lower electrode so that it can be temporarily fixed on an extension of the axis of the upper electrode during welding. A plurality of upper electrodes supported on the top of the machine and capable of only moving up and down, and a plurality of guide pins fixed in a row on a lower electrode moving member movably supported on a table protruding from the machine. The lower electrode, the lower electrode moving member,
A multi-stage cylinder mechanism for moving each lower electrode so that it can be temporarily fixed on an extension of the axis of the upper electrode during welding,
A nut welding device, comprising: a protective cover that covers a lower electrode other than the lower electrode facing the upper electrode during welding. 3. A plurality of upper electrodes supported on the upper part of the machine, which can only move up and down, and a plurality of guide pins fixed in a row on a lower electrode moving member movably supported on a table protruding from the machine. The lower electrode, the lower electrode moving member,
A multi-stage cylinder mechanism for moving each lower electrode so that it can be temporarily fixed on an extension of the axis of the upper electrode during welding,
A control mechanism for moving the moving member in accordance with the order of welding the nuts. 4. The apparatus according to claim 1, wherein said lower electrodes are arranged in a line in a horizontal plane, and said lower electrode moving member is configured to move linearly in a plane.
A welding device for a nut according to claim 2 or claim 3. 5. The apparatus according to claim 1, wherein said lower electrodes are arranged in a line on a circumference of a vertical plane orthogonal to said table, and said lower electrode moving member is configured to rotate and move around a horizontal axis. The welding device for a nut according to claim 1, 2 or 3, wherein