JPS6056488A - Method and device for producing welded can body - Google Patents

Abstract

PURPOSE:To prevent sparking in the stage of spacing electrodes by short circuiting mechanically a bypass circuit at the end period of electric resistance seam welding to weld the lap parts of a body for forming a can body thereby decreasing the current flowing near the terminal of the lap parts. CONSTITUTION:The lap parts 13'a of a body 13' for forming a can body are pressed directly or via a wire electrode by a bar-shaped electrode 1 and a rotary electrode 3 and the lap parts 13'a are seam-welded with electric resistance. A bypass circuit is mechanically short circuited to bypass the welding current at the point of the time when the center of the electrode 3 arrives at the position corresponding to just before the terminal where the parts 13'a end. The current flowing near the terminal of the parts 13'a is thus decreased. The pressurization between the electrodes 1 and 3 is then released.

Description

DETAILED DESCRIPTION OF THE INVENTION More specifically, the present invention relates to a method and apparatus for manufacturing a welded can body by electrical resistance seam welding of overlapping portions using a rod-shaped electrode and a rotating electrode.

The present inventors previously disclosed in Japanese Patent Application Laid-Open No. 55-70487 that the overlapping portion of a can body molded body is fixed to the rod electrode while moving either the rotating electrode or the rod electrode. proposed a technique for producing a welded can body by suppressing the welded can body with a rotating electrode and a rod-shaped electrode, applying electricity, and forming a welded part by electrical resistance seam welding of the overlapped part.

In this case, after the weld is formed, the rod-shaped electrode and the rotating electrode are usually in direct contact, but the two electrodes are immediately pulled apart in the radial direction, the welding body is moved axially, and the rod-shaped electrode Send from. At this time, if the electrodes are pulled apart while energized, the large welding current (usually on the order of several thousand amperes) will cause sparks that will damage both electrodes or the welded area.

As a first preventive measure against this trouble, a method can be considered in which a position sensor such as a proximity sensor detects the point in time when the rotating electrode leaves the welding part, cuts off the welding 12j current, and then performs the above-mentioned separation. However, in the case of high-speed production of 200 to 500 cans per minute, the following problems arise when this method is adopted.

In the case of high-speed production, a high-frequency current of about 200 to 600 Hz is usually used as the welding current, but due to the time and lag between detection and turning off the above-mentioned shutoff, and transient phenomena in the welding current, it is not possible to To avoid leaving a weld, place the rotating electrode at the weld (i.e., the overlap).
Even after leaving the end, the welding current continues to flow at 2 to 3 Hz.
It is necessary to move the material a considerable distance and then switch it off to perform the separation described above. When the length to be welded during a half cycle of alternating current, that is, the welding pitch, is 1 to 2 cm, the distance corresponding to 2) Iz is 4 to 8 cm. Therefore, it is necessary to maintain a state in which current can be passed between the rotating electrode and the rod-shaped electrode by that distance. During welding, the rotating electrode normally moves at a constant speed along the rod-shaped electrode, but after welding is completed, the welding speed is decelerated and continues to move along the rod-shaped electrode until it stops. If the rotating electrode and rod-shaped electrode remain in contact even after welding is completed, (a) it is necessary to widen the distance between the welded can body and the subsequent can body formed body, and (b) the can body formed body must be moved during this time. This results in waste, such as not being able to do so, and reduces the can manufacturing speed.

That is, it is desirable to separate the rotating electrode from the rod-shaped electrode immediately after welding is completed.

The above problem also occurs in the case of electric resistance seam welding of overlapping portions using a rotating electrode and a rod-shaped electrode via a wire electrode, as proposed in Japanese Patent Application Laid-Open No. 55-92281. Furthermore, as mentioned above, when the rotating electrode or wire electrode rides on the welding part (lower than the welding part) or on the overlapping part, the depression of these electrodes becomes larger due to the increase in the pressing force per unit area. This causes a problem. In addition, during high-speed welding, when the rod-shaped electrode (or the first wire electrode in contact with the rod-shaped electrode) and the rotating electrode (or the second wire electrode in contact with the rotating electrode) come into contact during the above-mentioned descent and descent, a weak spark There is a risk of causing gore and damaging the welding part or the electrode. Furthermore, in both parts of the overlapping part, the heat generated by welding is more pronounced than in other parts, and the same welding current When welding with a large amount of metal, there is a tendency for the molten iron to melt and protrude from the weld area. This is understood to be because, during welding, there is a current-carrying area of about 2 to 6 meters across the welding direction, but the length of this current-carrying area decreases at both ends of the overlapping part, resulting in a higher current density. Ru. For this reason, conventionally, when welding both ends of the overlapping portion, measures have been taken to reduce the welding current by performing electrical control.

However, as mentioned above, it is necessary to reduce the welding current with a margin of about 2 to 3 Hz due to temporal variations due to electrical detection of the control position and transient phenomena associated with welding current control. is occurring.

In this case, the part where the welding current is actually desired to be reduced is about 0.5 to 3W from the end face of the overlapping part, whereas the length where the welding current is to be reduced by electrical control is the welding pitch by 2g. If this is the case, it will be about 4 to 6 m+1. For this reason, the amount of welding current may be reduced to an unnecessary portion, so if the amount of reduction in the amount of current is increased, there is a risk that unwelded portions will be created. Therefore, there has been a desire for a means that can accurately reduce the welding current by the necessary amount at both ends of the overlapping portion.

The present invention aims to solve the problems of the prior art described above.

In order to achieve the above object, the present invention presses the overlapping part of the can body molded body whose overlapping part is fixed to a rod-shaped electrode against the rod-shaped electrode and the rotating electrode directly or through a wire electrode. In the method of manufacturing a welded can body by electrical resistance seam welding the overlapping portion, when the center of the rotating electrode reaches a position corresponding to just short of the end of the end of the overlapping portion, By mechanically short-circuiting a bypass circuit through which the melting current can bypass, control is performed to reduce the current flowing through the overlapping portion, and pressure is applied between the hindlimb rotating electrode and the rod-shaped electrode. The present invention provides a method for manufacturing a welded can body, characterized in that when the two electrodes are separated from each other, an electric gap is not generated between the electrodes.

Furthermore, the present invention presses one mating part of the can body molded body, the overlapping part of which is fixed to the rod-shaped electrode, by the rod-shaped electrode and the rotating electrode directly or through a wire electrode, and In a method of manufacturing a welded can body by electrical resistance seam welding of parts, before welding is started, a pi-gas circuit that can bypass the welding current is short-circuited in advance, and the rotating electrode Control is performed to reduce the current flowing through the starting end of the overlapping part by mechanically synchronizing and opening the 9427 circuit at the point when the starting end A1a of the overlapping part is slightly passed through. The present invention provides a method for manufacturing a welded can body characterized by the following.

Furthermore, the present invention provides a method for pressing the overlapping portion of the can body molded body, the overlapping portion of which is fixed to the rod-shaped electrode, against the rod-like electrode and the rotating electrode, either directly or via a wire electrode. In an apparatus for manufacturing a welded can body by electrical resistance seam welding of parts, the rod-shaped electrode and the rotating electrode each include:
The device is connected to a first end and a second end of a welding power source, and includes a piston roll that can be electrically connected to the rotating electrode, and a center of the rotating electrode that is connected to the end of the overlapping portion. a conductive bar that contacts the binogus roll when it reaches a corresponding position slightly in front and is permanently connected to a first end of the welding power source; means for axially separating the rotating electrode from the welding can body; and a means for moving the welded can body in the axial direction and sending it out from the rod-shaped electrode.

The present invention will be described below with reference to the drawings which are examples.

In FIGS. 1 and 2, a rod-shaped electrode 1 is fixed to the lower tip of a mandrel 2 fixed to a frame (not shown) so as to extend in the axial direction of the mandrel 2, that is, in the horizontal direction. The rotating electrode 3 is rotatably supported by a support 4 so as to face the rod-shaped electrode 1, and the support 4 is supported along a slide rod 6 (not shown) fixed to the upper surface of the support plate 5. It is configured to reciprocate in the direction of the arrow, that is, in the direction in which the rod-shaped electrode 1 extends, via the connecting rod 7 by means of a crank mechanism. Further, the support plate 5 is configured to be movable up and down via a lifting rod 8 by a drive mechanism (for example, a cam mechanism) not shown. In addition, 8a
is a coil spring that applies pressing force to the overlapping part during welding.

Reference numeral 9 denotes a bypass roll, which is pivotally supported by the support 4 so that its circumferential surface is always in contact with the circumferential surface of the rotating electrode 3. Reference numeral 10 denotes a conductive wire fixed to the upper surface of the support plate 5 via an electrical insulator (not shown). - (for example, made of a copper bar), and a notch 10a extending in the direction of arrow A is formed on its upper surface. The conductive bar 10 and the mandrel 2 are connected to a first end 11a1 on the secondary side of a welding power source 11 (for example, a high frequency oscillator of 200 to 600 Hz), and the rotating electrode 3 is connected to a second end 11a2. There is.

13 is a can body molded body having an overlapping part 13a,
It is formed from a metal plate blank such as tin-plated steel or tin-free steel. The can body molded body 13 is moved from the left side of the figure to the right side along the mandrel 2 by the feeding rod 1 which reciprocates.
The rear end surface (the left end surface in the figure) is engaged with a finger 15 attached to 4, and is fed one after another intermittently at predetermined intervals. After being accurately sent to the welding station B, which corresponds to the position of the welded can body 13' in FIG. are electrical resistance seam welded, usually mash seam welded, to form a welded can body 13' having a weld 13'a.

In FIG. 2, the rotating electrode 3 moves from the right side of the figure to the left side,
This shows the state where welding is almost completed. Center 3a of rotating electrode 3
However, the welded part 13'a (strictly speaking, the unwelded overlapping part 13
Slightly before the end 13'a of a), usually about 3I+++
++ or less, preferably about 2 or less k l 3'lx
2 (hereinafter referred to as the contact start position) (see Fig. 3), the bypass roll 9 and the conductive bar 1
0 starts contact, the left end 1 of the notch 10a
Since the position of 0a1 is determined, that is, the bypass roll 9 is not in contact with the conductive bar 10 due to the notch 10a, the welding current is applied to the first welding power source.
The overlapping portion 13a is welded by flowing through the path of the end portion 11a1→mandrel 2→rod-shaped electrode 1→overlapping portion i3a→rotating electrode 3→second end portion 11a2. However, the center 3a of the rotating superposition 3 is at the contact start position In 13"a
2, when the bypass roll 9 and the conductive bar O contact each other, the current flows to the first Xil! Part 11
al→conductive bar 10→bihas roll 9→rotating electrode 3
→It also flows through the bypass circuit of the second end 11a2. Therefore, the center 3a moves from the contact start position 13'a2 to the end 1.
The currents flowing through both paths flow in parallel until reaching 3'al.

In this way, from the contact start position 13'a2 to the end 1.
End part 13'a3 which is the section until reaching 3'a1
The current flowing through the end 13'a3 decreases, and the end 13'a3 can be successfully welded like the other overlapping parts 13a. (for example, changing the size of the end 13
It can be freely adjusted by using a copper alloy with slightly low conductivity for the surface layer of the portion of the conductive bar 10 corresponding to 'a3. The distance from the end 13'a1 that reduces this welding current may be determined as necessary from the notch 10a of the conductive bar 10.
It can be changed freely and accurately by changing the position of .

Immediately after the center 3a of the rotating electrode passes the position corresponding to the end 13'al, the lifting rod 8 is lowered to pull the rotating electrode 3 away from the welding can body 13' in the radial direction.

During this separation, current flows through the bypass circuit, so there is no risk of spark generation.

Immediately after the above passage, the welded part 1 at the end 1:3'a,
Due to the difference in level based on the end face of 3'a, there is little risk that the rod-shaped electrode 1 and the rotating electrode 3 will come into contact with each other. It is preferable to prevent the rotating electrode 3 from rising after passing through by providing a cam-type locking mechanism or the like that engages the cam roll 16 fixed by a support (not shown) on the electrode 35.

In this manner, the amount of welding current can be controlled at the welding end and no sparks are generated, so that a satisfactory welding condition can be obtained.

Even after the above-described rotating electrode 3 is separated from the welded portion 13'a and the rod-shaped electrode 1, the rotating electrode 3 moves leftward in FIG. 2 along the rod-shaped electrode for a while and then stops. Meanwhile, the current is flowing through the pi-gus circuit and there is no need to cut in and flood it.

The above rotating electrode 3 is separated, and the rod-shaped electrode 1 and the rotating electrode 3 are separated.
At the point when a gap is created between the welded can body 13' and the welded can body 13' shown in FIG. Around this time, the rotating electrode 3 starts to move to the right and upward in FIG. 2, and the molded can body 13 is stationary and fixed at the position of the welded can body 13' in FIG. 2, and welding becomes possible. At this point, the rotating electrode 3 is moved to the position shown in FIG.
The starting end of a (corresponding to the terminal i3'a+) is contacted.

Then, while pressing the overlapping portion 13a, it is moved to the right. At that time, the center 3a of the rotating electrode 3 is at the contact start position 1
The welding current and the bypass current flow in parallel until the position corresponding to 3'aZ is reached. Thereafter, the piezo roll 9 and the conductive bar 10 are in a non-contact state until the piezo roll 9 comes into contact with the right end 10a2 of the notch 10a.
Only welding current flows.

At the end of the overlapping part, the welding current decreases only in the section where the welding current and the inomous current flow in parallel, and the amount of current is πA? Since this can be adjusted by changing the impedance of the circuit, a normal welding condition can be obtained without overheating the end of the welded part and causing a welding failure as described above.

The position of the right end portion 10a2 is the same as that of the left end portion 10a1, so the center 3a of the rotating electrode is the overlapped portion, and therefore the welded portion 13.
When it reaches a position corresponding to about 2+n+++ or less, preferably about 0.5 key or less before the right end of 'a,
It is determined that the bypass 1 call 9 and the electrical conductors begin to re-contact. - One welding process after the rubber roll 9 comes into contact with the right end 10a2 is the same as that after it comes into contact with the left end 10a1 described above. Note 17
is a cam roll and operates in the same way as the cam roll 16.

4, 5, and 6 show other embodiments of the present invention. Parts with the same reference numerals as in FIGS. 1 and 2 indicate similar parts.

The rotating electrode 23 is coaxially supported by a support body 24 with a power supply roll 28 and an inoyasu roll 29 .

A wire electrode 23x is inserted through the circumferential recess 23a of the rotating electrode 23. Four parts 21a extending in one axial direction of the rod-shaped electrode 21
The wire electrode 21X is also inserted through the wire electrode 21X. The support body 24 is a slide fixed to the upper surface of the support plate 5.

It is configured to be able to reciprocate along the rod 6 in the axial direction of the mandrel 2, that is, in the direction of the arrow, via a connecting rod 7. The support plate 5 is adapted to be moved up and down via a lifting rod 8.

19 and 20 are A+J+, a power supply par 19 and a conductive bar 20 extending in the axial direction of the mandrel 2, respectively, and both are isolated by an electrically insulating layer 18. The lower surface of the conductive bar 20 is
It is formed in the same shape as each of the power supply pars 19 except for the notch 20a. The power supply par 19 and the conductive bar 20 are attached to a holding frame 25 fixed to the support plate 5 at their respective ends by a vertical pin 26 and a coil spring 27.
It is held so that it is constantly pulled downward.

Therefore, the bottom surface 1 on both sides of the notch 20a of the conductive bar 20
Along 9a, power supply roll and Guinox roll 2
When the phase 9 moves, these peripheral surfaces and the bottom surface 20b
1.20b2. and 1? Sufficient pressing force is applied between 1L and contact electrical resistance becomes extremely small. The power supply nozzle 19 and the conductive bar 20 are connected to the second end 11a2 and the first end of the welding power source 1 through feeders 30 and 31, respectively, and are connected to the mandrel 2.
is connected to the first end port '1.

The notch 20a of the conductive bar 20 is the same as that of the conductive bar 10 in FIG.
Similarly to the notch 10a, the left In edge b20a1 and the right edge 20a2 are such that the center of the rotating electrode 23 is
The left and right ends of the power transmitting formed body at welding station B, that is, the left end 1:3 of the welded can body 13' in FIG.
When reaching the position corresponding to 'x' and right end 13'y, slightly inside, ・gui・gusu C1-/l/ 29 respectively reach left end 20a 1oj hiti Ill end 2
011.2.

There is a notch 32 on the left side of the bottom surface 20bl, and a notch 33 on the right side of the bottom surface 20b2.
and conductive wire 20. Notch 32.
33 is after welding is completed, 4 times electrode 23 force) spiral electrode 23x
The wire electrode 23 It was established for the purpose of

That is, after the rotating electrode 23 moves to the right and welding is completed, the rotating electrode 23 is further moved to a position corresponding to the bypass roll 29a in FIG. 3, that is, the power supply roll 28 and the bypass roll 29 are located below the notch @3. Shift it slightly to the right. Then, due to the action of the coil spring 27, the lower surfaces of the power supply bar 19 and the conductive bar 20 are brought into contact with the holding frame 2.
Although it slightly descends until it comes into contact with the upper surface of the positioning pin 34 fixedly attached to Since a gap remains, the rotating electrode 23 can freely rotate while the wire electrode 23x can be freely pulled out. Normally, the wire electrode 21x that passes through the rod-shaped electrode 21 is made up of one wire that is continuous with the wire electrode 23x, so during the above-mentioned stretching, the portion of the wire electrode 21x that has passed through the rod-shaped electrode 21 is also pulled out at the same time. At this time, after the piezo roll 29 reaches the notch 32 or 33 of the conductive par 20 and the conductive par 20 is welded, the pino Rs current is cut off while the pie gas roll 29 is in contact with the conductive par 20. must be done.

Welding is performed in the above apparatus as follows.

At the end of the previous welding, the lifting rod 8 is lowered and the rotating electrode 23 is moved to a position corresponding to the bypass roll 29b in FIG.
Ift is at a low level (the level in Figure 4),
While the wire electrode 23x is being pulled out, the next can body molded body is sent to the position of the welded can body 13' from the left side of the figure at a position of 4if+i.

Immediately the rotating electrode 236J: starts moving to the left, and the bottom surface 2
In 0b1, pi gas roll 29 and conductive par 20
At the same time, the power supply roll 28 and the power supply bar 19 also come into contact with the bottom surface 19a. After contact between the bypass roll 2 and the conductive bar 20 is started, the power is turned on, and the first end 11a1 of the power supply → the conductive par 20 → the bypass roll 29 → the power supply roll 28 → the power supply bar 19 → the second end A current flows through the bypass circuit consisting of the end portion 11a2.

The center of the rotating electrode 23 is located at the left end of the molded can body, that is, at the third
At the same time as it reaches the left end 13'x in the figure, the rising rotating electrode 23 bends the overlapping part via the line electrode 23x to a position where it can be suppressed against the line electrode 21x of the rod-shaped electrode 21. reach it.

Therefore, in parallel with the current flowing through the pi-gus circuit, the second end 11a2 of the welding power source → power supply bar 19 → power supply roll 2
8 → Rotating electrode 23 → Line electrode 23x → Overlapping part → Line electrode 21x → Rod-shaped electrode 21 → Mandrel 2 → First end 11
Welding current flows through a1.

Bypass roll 29 is conductive roller 20 (7) Bottom surface 20b
.

The currents flow in parallel until the contact with the conductive part 20 is released, that is, until the contact reaches the notch 2Qa of the conductive part 20. Therefore, the welding current can be reduced in that part, and the end of the welded part will not be overheated and cause welding failure, and normal welding will be performed. The amount of decrease in the welding current can be changed as necessary by adjusting the impedance of the Pino-RS circuit.

Thereafter, the rotating electrode 23 is moved to the right, and electrical resistance seam welding (preferably Manoshi welding) of the overlapped portions is performed to produce a welded can body 13' having 13 welded portions.

Because of the notch 20a between them, no bypass current flows through the bypass roll 29, but the right side of the welding part 11:l, 113
When the bypass roll 29 reaches a position slightly before y, the bypass roll 29 comes into contact with the bottom surface 20b2, thereby short-circuiting the pi-zos circuit and causing a binogusumi flow.

At this time, as in the case of the first embodiment described above, the current flowing through the end of the welded portion can be reduced, making it possible to obtain a preferable welding condition. Because of the bypass current, there is no risk of sparks even if the rotating electrode 23 is lowered immediately after welding.
3 and a linear electrode 21 stretched over a rod-shaped electrode 21. Since x and 23x do not come into contact with each other, the linear electrodes 21x and 23x are not damaged.

After welding is completed, while the bypass roll 29 is in contact with the bottom surface 20b2 of the conductive bar 20, a switch (not shown) built into the power supply is turned off, and the current flowing through the bypass circuit is stopped. After that, the bypass roll 29 and the conductive bar 20
The contact with the bypass roll 29 is broken, and the bypass roll 29
The rotating electrode 23 stops when it reaches the 0'D notch 33. After the contact between the bypass roll 29 and the conductive bar 20 is broken, the wire electrode 23x is pulled out by a predetermined length.

The present invention is not limited to the above embodiments,
For example, an electrically insulating layer may be formed in the notch.

Also, wire electrodes may be used in the apparatuses shown in FIGS. 1 and 2. However, in this case, it is necessary to provide the conductive bar 10 with cutouts corresponding to the cutouts 32 and 33 in FIG. 4. In addition, the bypass circuit is not limited to the system using a bypass roll as in this embodiment, and a mechanical mechanism for reversing contact and separation in synchronization with the movement of the rotating electrode is used as a secondary source of the welding power source. By providing it on the side, it can be used as a bypass circuit.

According to [Misfire], it is possible to reduce the amount of welding current so that the current density does not increase at the end of the weld, the effect of normalizing the melting state of the end of the weld, and the effect of reducing the welding temperature at the end of welding. Since a bypass current flows, there is an effect that no sagging occurs when the rotating electrodes are separated.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of the device according to the first embodiment of the present invention, Fig. 2 is a cutaway front view of the work section taken along the line FIG. 4 is an enlarged drawing of part 0, and FIG. 4 is a front view of the device according to the second embodiment of the present invention. FIGS. FIG. ■, 21... Rod-shaped electrode, 3.23... Rotating electrode, 3
a...Center, 9, 2 c...Bypass roll, 1
0゜20... Conductive bar, 11... Welding power source, lla
,...first end, 1la2...second end, 13
... Can body molded body, 13a... Overlapping portion, 13'.
... Welded can body, 13'a1... End, 13'a2.
...Position slightly before the end, 13'a3...End, 21X...Line electrode, 23X...Line electrode. Patent applicant Akira Kishimoto Figure 1 ■'' Figure 3 - Figure 6 9

Claims (4)

[Claims] (1) The overlapping portion of the can body molded body whose overlapping portion is fixed to a rod-shaped electrode is pressed by the rod-shaped electrode and the rotating electrode through the a-contact or the wire electrode, and the overlapping portion is electrically pressed. In the method of manufacturing a welded can body by resistance seam welding, a bypass circuit is provided through which the welding current can be bypassed when the center of the rotating electrode reaches a position corresponding to just before the end of the overlapping part. Control is performed to reduce the current flowing near the end of the overlapping portion by mechanically shorting, and then the pressure between the rotating electrode and the rod-shaped electrode is released, and when the two electrodes are separated, A method for manufacturing a welded can body, characterized in that electric sparks are not generated between the electrodes. (2) The overlapping portion of the can body molded body whose overlapping portion is fixed to the rod-shaped electrode is pressed against the rod-shaped electrode and the rotating electrode directly or through the wire electrode to separate the overlapping portion. In a method of manufacturing a welded can body by electrical resistance seam welding, a bypass circuit that can bypass the welding current is short-circuited in advance before welding starts, and the rotating electrode is connected to the overlapped portion. A welded can body characterized by controlling the current flowing near the starting end of the overlapping part by mechanically synchronizing and opening the bypass circuit when the current passes slightly past the starting end. Production method. (3) The method for manufacturing a welded can body according to claim 1 or 2, wherein the length of the end of the welded part where the pie-yield flow and the welding current flow in parallel is 31+II+1 or less. (4) The overlapping part of the can body molded body whose overlapping part is fixed to the rod-shaped electrode is pressed by the rod-shaped electrode and the rotating electrode directly or through the wire electrode, and the overlapping part is electrically In an apparatus for manufacturing a welded can body by resistance seam welding, the rod-shaped electrode and the rotating electrode are each connected to a first welding power source.
and a second end of the overlapping portion, the device includes a bypass roll that can be electrically connected to the rotating electrode, and a position where the center of the rotating electrode corresponds to a position slightly in front of the distal end of the overlapping portion. an electrically conductive bar that contacts the piezo roll and is permanently connected to a first end of the welding power source when the rotating electrode is reached, a means for axially separating the rotating electrode from the welding can body, and the welding can An apparatus for manufacturing a welded can body, comprising means for moving the body in the axial direction and delivering it from the rod-shaped electrode.