JPS60213367A - Manufacture of welded boiler drum - Google Patents

Abstract

PURPOSE:To manufacture a welded boiler drum having small protrusion of metal and good weld zone by making the center of shaft of an internal electrode roll intersect obliquely a plane that passes axial line of a boiler drum fromed body and a welding point and welding the boiler drum between an external electrode roll. CONSTITUTION:In a method to obtain a welded boiler drum 12 by electric resistance mash seam welding side superposed part 11b of a boiler drum forming body 11 between the internal electrode roll 1 and external electrode roll 2 through the first and second line electrodes 3, 4, the center of shaft of above-mentioned internal electrode roll 1 is made to intersect obliquely a plane that passes above- mentioned axial line 11a and welding point 13 on a plane that passes the center of shaft 2a and intersects the axial line of the boiler drum formed body 11 at right angles, and projection of the electrode face 1b of the internal electrode roll 1 to the plane is formed to an ellipse. Thus, apparent diameter of above-mentioned electrode face at welded part is enlarged and the length of contact is made larger, and a good weld zone 24 of small step and small protruded metal and free from inside fissure is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a welded can body, and more specifically, to a method for manufacturing a welded can body, and more specifically, using an internal electrode roll and an external electrode roll, the overlapping portion of the side surface of a can body formed body is electrically resisted via a wire electrode. The present invention relates to a method of manufacturing a welded can body by welding a seam.

When manufacturing relatively small-diameter welded can bodies such as carbonated beverage cans and juice cans (for example, approximately 53 internal diameters) by electrical resistance pine seam solid phase welding, the diameter of the internal electrode roll is limited to the internal diameter of the welded can body. However, since there is no such restriction, the external electrode roll has a relatively large diameter.

The reason why the external electrode roll has a large diameter is that the contact length between the overlapping portion and the wire electrode, that is, the length of the current-carrying area is large t'! !
The formation of a heat-affected zone (which refers to the area where the structure has changed during welding and corresponds to fusion welding) is performed smoothly, and a good welded area with a small amount of protruding metal is obtained. This is because it becomes easier to get caught. That is, the greater the amount of matting and the amount of crushing of the side surface overlapping portions, the smaller the step difference in the resulting welded portion, and in this respect, it becomes easier to repair the welded portion satisfactorily with paint or the like. On the other hand, the larger the mating amount is, the larger the amount of protruding metal becomes, and from this point of view it tends to be difficult to perform the above-mentioned satisfactory repair.However, when the mating amount is the same, the longer the contact length is, the more the amount of protruding metal is. It becomes less.

However, in the past, the diameter of the internal electrode roll was constrained by the inner diameter of the welded can body to be formed as described above, and in many cases had to be relatively small, so the contact length on the internal electrode roll side was limited. There was a problem in that it became relatively short and the amount of mashing could not be increased too much due to the amount of protruding metal, and the step difference in the welded part could not be reduced to a satisfactory value.

Furthermore, if the diameter of the inner electrode roll is smaller than that of the outer electrode roll, the current density differs in the thickness direction of the welded portion and increases toward the inner electrode roll. As a result, the heat-affected zone is shifted toward the internal electrode roll.
As described in No. 8, a problem arises in that cracks that extend in the circumferential direction are likely to occur on the inner surface of the welded 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 uses an internal electrode roll that supports a first wire electrode and an external electrode roll that supports a second wire electrode to form a side surface overlapping portion of a can body formed body. In a method for manufacturing a welded can body by electrical resistance seam welding through a first wire electrode and a second wire electrode, at least the axis of the inner electrode roll passes through the axis of the outer electrode roll. a first perpendicular to the axis of the can body molded body;
and is oblique to a second plane passing through the axis and the welding point, and the projection of the electrode surface supporting the tenth wire electrode of the internal electrode roll onto the second plane is The present invention provides a method for manufacturing a welded can body characterized by forming an elliptical can body.

The present invention will be described below with reference to the drawings. 1st
In the figure, 1 is an internal electrode roll, 2 is an external electrode roll, and 3 and 4 are a first wire electrode and a second wire electrode, respectively, which are supported by the internal electrode roll l and the external electrode roll 2 during welding. .

5. 6 and 7 are guide rolls that guide the first line electrode, and 8 and 9 are idle rolls that guide the second line electrode. Reference numeral 10 denotes a mandrel which guides the can body molded body 11 and the welded can body 12 formed by the can body molded body 1 moving in the direction of arrow A. (see) is located on a plane 14 perpendicular to the axis 11a of the molded can body 11 or the axis of the simandrel 10, and extends in the horizontal direction, as in the conventional case. Axis center 1a of internal electrode roll 1
is on the plane 14 and obliquely intersects with the plane 15 passing through the welding point 13 and the axis 11a, so the first wire electrode 3
Supporting the truncated conical side surface electrode surface 1b (upper axis 1
As shown in FIG. 1, the projection of the circle perpendicular to a) onto the plane 15 is an ellipse whose major axis is parallel to the axis 11a. In this specification, the welding point 13 refers to a plane 14 within the current-carrying area 2o where the welding current 22 flows to the side surface overlap portion 11b between the first wire electrode 3 and the second wire electrode 4 to perform welding. Point to the center point of the upper part (see Figure 3).

As shown in FIG. 2, the internal electrode roll 1 is pivotally supported by the internal electrode roll holding portion 10a of the mantle 10 by a mail bearing 16. As shown in FIG.

17 is cooling water 18 for cooling the internal electrode roll 1
It is a conduit hole. The internal electrode roll 1 is fed with a welding current from a DC or AC power source (not shown) via a mandrel 10 and a liquid conductive agent 19.

The electrode surface 1b of the internal electrode roll 1 is formed on a truncated conical surface IC, and at a position facing the welding point 13,
It is parallel and horizontal to the electrode surface 2b (the surface supporting the second wire electrode 4) of the external electrode roll, and its diameter is the electrode surface 2b.
Although it is smaller than the diameter of the electrode surface 1b in the vicinity of the welded portion 2o, since the projection of the electrode surface 1b onto the plane 15 is an ellipse whose long axis direction is parallel to the axis 11a, as described above, the electrode surface 1b near the welded portion 2o ) If expressed strictly, electrode surface 1
The apparent radius of curvature r of the center line in the width direction of b increases.

Therefore, by appropriately determining the inclination angle θ of the axis 1a of the inner electrode roll 1 with respect to the plane 15 (FIG. 2) and the diameter of the electrode surface 1b, the apparent diameter d of the electrode surface 1b can be adjusted. It can be made substantially equal to the diameter of the electrode surface 2b. For example, if the diameter of the electrode surface 2b is 85 mm and the diameter of the electrode surface 1b is 26 mm for the can body molded body 11 with an outer diameter of 53 mm, the electrode surface can be adjusted by setting the inclination angle θ to about 15 degrees. The apparent diameter d of 1b can be 85 m.

Note that the side wall portion IC of the disk-shaped portion protruding from the upper end of the electrode surface 1b is for guiding the first wire electrode 3, and extends perpendicularly to the electrode surface 1b. The width of the first line electrode 3 is also determined to be small.

As shown in FIG. 2, since the internal electrode roll 1 is inclined, it is on one side with respect to the plane 15, that is, on the left side in the figure. Therefore, in order to use the internal electrode roll 1 having the electrode surface 1b with a diameter as large as possible, the can body molded body 11, which is originally cylindrical and has a circular cross section, is rotated horizontally as shown in the figure, at least in the vicinity of the current-carrying area 20. It is preferable to elastically shape the cross-section into an ellipse in the long axis direction. This plastic surgery is
This is carried out by a group of guide rolls 21 that surround the molded can body 11 and are arranged so that each axis is located on the plane 14. As shown in FIG. 1, the welded portion 11C of the formed can body 11 is released from the restraint by the guide rolls 21 and elastically returns to its original shape, forming the welded can body 12 with a circular cross section.
is obtained.

The welded can body is manufactured using the above-mentioned apparatus as follows.

A blank of a metal plate, for example, a tin-plated steel plate, is rolled up to form a side overlapped portion 11b (the circumferential width of which is usually 0.3 to 0.0 mm).
A cylindrical can body formed body 11 having a relatively small diameter is formed and fed along the mandrel 10 in the direction of the arrow as shown in No. 11K. The can body molded body 11 is made of a hollow roll 21.
At a position along the axis 11a direction near the current-carrying region 20, its cross section is elastically shaped into an elliptical shape capable of enclosing the internal electrode roll holding portion 10a of the mandrel 10.

Then, the side surface overlapping portion 11b is energized and pressed by the inner electrode roll 1 and the outer electrode roll 2 via the first and second wire electrodes 3 and 4, so that electric resistance mash gnome solid box welding, so-called Forge welding is performed to form a weld 24. Immediately (the welded portion 11C of the can body molded body returns elastically), a cylindrical welded can body 12 is obtained.

In the above welding, as mentioned above, the electrode surface 1b of the internal electrode roll, which originally has a relatively small diameter, has an apparent diameter increased, preferably substantially equal to the diameter of the electrode surface 2b of the external electrode roll. Therefore, as shown in FIG. 3, the heat affected zone 23 is formed approximately at the center of the welded portion 24 in the thickness direction, and there is therefore no risk of cracks occurring on the inner surface. In addition, since the contact length between the first wire electrode 3 and the side surface overlapping portion 11b is increased, even if the amount of pine 7 is increased, the amount of protruding metal does not increase. A welded can body 12 having a relatively small diameter and having a good welded portion 24 with a small amount of metal can be manufactured.

The outer electrode roll is shown at 32 in FIG.
The reed may be configured to be on the same plane as the axis 1a and parallel to the axis 1a. In this case, the apparent diameter of the electrode surface 32b of the external electrode roll 32 that supports the second wire electrode 4 also increases, and accordingly, it is possible to obtain a welded part with a smaller step and a smaller amount of protruding metal. can.

Further, as shown in FIG. 5, the outer electrode roll 42 has an axis 42a of the inner electrode roll 1 of the type shown in FIG.
It is configured to be on the same plane as the axis 1a of and to extend in the vertical direction.

In this case, the electrode surface 42b extends in a direction perpendicular to the axis 42a, and therefore in a horizontal direction. In this case as well, the same effects as described above can be achieved. Note that in FIGS. 4 and 5, parts with the same reference numerals as those in FIGS. 1, 2, and 3 indicate similar parts.

According to the present invention, the apparent diameter of the electrode surface of the internal electrode roll is increased, so even if a relatively small diameter internal electrode roll is used due to the restriction of the diameter of the can body molded body, the surface of the internal electrode roll is small and there is no protruding metal. The effect is that it is possible to manufacture a large seam electric resistance welded can body having a small amount of good welded parts.

Furthermore, when the apparent diameter of the electrode surface of the internal electrode roll is made substantially equal to the diameter of the electrode surface of the external electrode roll, there is an advantage that generation of cracks on the inner surface of the welded portion can be prevented.

[Brief explanation of drawings]

FIG. 1 is an explanatory front view showing the state of a first example in which the method of the present invention is implemented, FIG. 2 is an enlarged vertical sectional view taken along the line ■-■ in FIG. 1, and FIG. FIG. 2 is a longitudinal sectional view taken along the line 1-111 of FIG. 2, showing a state in which welding is performed by the method of the present invention, and FIGS. FIG. 2 is a schematic side view showing the first and second examples. 1... Internal electrode roll, 1a... Axis center, 1b...
Electrode surface, 2.32.42...External electrode roll, 2a. 32a, 42a... Axial center, 3... First wire electrode,
4... Second wire electrode, 11... Can body molded body, 11a
... Axis line, 12 ... Welded can body, 13 ... Welding point,
14...first plane, 15...second plane. Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) An internal electrode roll that supports the first wire electrode, and a second
Using an external electrode roll that supports a wire electrode, electrical resistance seam welding is performed on the overlapping side portions of the can body molded body through the first wire electrode and the second wire electrode to form a welded can body. In the manufacturing method, at least the axis of the inner electrode roll is on a first plane passing through the axis of the outer electrode roll and orthogonal to the axis of the can body molded body, and the axis and the welding point are aligned with each other. is oblique to a second plane passing through the inner electrode roll, and the projection of the electrode surface supporting the first wire electrode of the inner electrode roll onto the second plane forms an ellipse. A method for manufacturing a welded can body.