JPS62275582A - Mash-seam welding can shell - Google Patents

Abstract

PURPOSE:To eliminate the peeling off part and thin part of a paint and to enable a stabilized coating by forming the step difference part having the fence part about parallel to the welding main face nearly in a regular order repeatedly in the welding direction. CONSTITUTION:The outer face step difference part 5 where a material extends to the outer part in the peripheral direction is formed on the outer face side welding main face 3 of the mash-seam weld zone 2 of a welding can shell 1 and the inner face side is made in the similar shape as well. On this step difference part 5 a fence part 8 is formed about in a regular order repeatedly in the welding direction. And the sum of the length of this step difference part 5 and of the boundary part of the fence part 8 is taken >=about 20% of the total length of the weld zone. When a paint 13 is coated on such outer side face of the weld zone 2, a comparatively thick part is formed because of the paint 13 collecting in the vicinity of the boundary parts 10, 14, so the peeling off of the paint film and thin part are eliminated and a staple painting can be performed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a pine seam welded can body used for beer cans, carbonated beverage cans, and the like.

(Prior Art) Welded can bodies used for beer cans, carbonated beverage cans, etc. are usually made by overlapping opposing edges of metal blanks such as tin-plated steel sheets, and then electrically resistive seam welding of the overlapping portions (for example, (by the method disclosed in Japanese Patent Publication No. 54-26213).

The thickness of this maunyu seam weld is usually about 1.1 to 1.8 times, preferably about 1.3 to 1.6 times, the thickness of the blank. This results in a stepped portion with an irregular cross section. To prevent rust and corrosion caused by the contents, this welded part is usually coated with paint, dried, and
Repair is done by forming a paint film, but because of this step, missing or very thin parts of the paint film tend to occur near the corner of the main surface of the weld at the step, so the repair effect is not satisfactory. The problem was that it was difficult to obtain.

(Problems to be Solved by the Invention) An object of the present invention is to provide a welded can body with pine seams that has improved repairability with paint.

(Means for Solving the Problems) In the matsushi seam welded can body of the present invention, on at least one side of the welded portion, the step portion having the shelf portion approximately parallel to the welding main surface is repeated four times in the welding direction and is approximately regularly arranged. It is characterized by being formed.

Note that the shelf portion preferably has a repeated wave shape when viewed in plan, and the total length of the boundary between the step portion on the main surface of welding (hereinafter referred to as the upper step portion) and the shelf portion is: Preferably, it is about 20% or more of the total length of the welded portion.

(Function) The applied paint tends to accumulate near the boundary between the upper and lower step portions and the shelf portion substantially parallel to the main welding surface. Therefore, on the surface side of the welded portion having the above-mentioned shelf, missing or extremely thin portions of the coating film are less likely to occur.

In addition, the step portions are repeatedly formed almost regularly in the welding direction, and there are no large fluctuations in unevenness, such as large protruding portions, along the welding direction, so the coating can be applied in a stable manner.

(Example) In FIGS. 1 and 2, 1 is a welded can body, and 2 is a welded seam. The welding part 2 has an outer main welding surface 3 and an inner welding main surface 4 that substantially correspond to the outer and inner surfaces of the overlapping part, respectively, and the end face of the overlapping part (7 in FIG. 2) during welding. The outer surface side step part 5 and the inner surface side step part 6 are formed by surrounding materials (corresponding to each other) extending outward in the circumferential direction.

Each of the stepped portions 5 and 6 is formed with a substantially flat shelf portion 8 and 9 that extends substantially parallel to the main welding surface. As clearly shown in FIG. 1, the shelves 8, 9 are formed repeatedly and substantially regularly in the welding direction. The shelves 8 and 9 are usually wavy in accordance with the waveform of the welding current, that is, the part corresponding to the peak value of the welding current is a peak, and the part corresponding to the O value of the welding current is a valley. Becomes a department.

A boundary portion 10 between the upper step portion 5a and the shelf portion 8, which is a portion of the step portion 5 on the side of the outer main welding surface 3 and which preferably has a gently curved surface, extends linearly in the welding direction. Similarly, the boundary portion 11 between the upper step portion 6a of the inner surface side step portion 6 and the shelf portion 9 also extends linearly in the welding direction.

In the case of FIG. 1, the shelf 8.9 is formed over the entire length of the weld, but as in the weld 12 shown in FIGS. 3 and 4, the shelf 18 is repeated at the step 15. , may be formed substantially regularly and intermittently. In other words, no shelf is formed in the portion 15b of the stepped portion 15 near the valley, as clearly shown in FIG. Even in such a case, the total length of the boundary part 20 between the shelf part 18 and the upper step part 15a is about 20 inches or more of the total length of the welded part, preferably about 5 inches.
It is desirable that it be 0 or more in order to improve the repairability of the paint.

For example, if the paint 13 is applied to the outer surface of the welded part 2, the second
As shown in the figure, a boundary portion 10 between the shelf portion 8 and the upper step portion 5a
Above the vicinity, and also at the boundary 14 between the shelf 8 and the lower step 5b.
A pool of paint 13, that is, a relatively thick part of the paint, tends to form near the top, and due to this, the area near the corner between the upper step 5a and the main welding surface 3, and between the shelf 8 and the lower step 5b.
This prevents the paint film from missing or becoming extremely thin near the corners.

For this purpose, the height h of the shelf section 8 (9) from the can body body surface 1a on the side of the lower step section 5b is 0.2 H-0.81, where H is the height of the main welding surface 3. (Preferably 0.4H
It is preferably within the range of ~0.6H.

Further, the maximum width W in the circumferential direction of the shelf portion 8 (9) is preferably in the order of 0.1 to 0.7, and preferably in the order of 0.2 to 0.4.

A welded can body having a mash welded portion as described above is manufactured, for example, in the following manner.

Overlapping portions 21 of opposing edges of a can body preform 19 formed by rolling a metal blank such as a tin-plated steel plate, tin-free steel, an ultra-thin nickel-plated steel plate, or an ultra-thin nickel-tin composite plated steel plate, A wire electrode 22,23 having a cross-sectional profile shown in FIG.
welding.

Note that 24 and 25 are an inner electrode roll and an outer electrode roll, respectively.

The line electrodes 22 and 23 have a main portion 26 whose surface facing the overlapping portion 21 is flat in cross section, and a side edge protrusion 27.
The side edge protrusion 27 has a sloped surface 27a connected to the main portion 26,
Projecting surface 27'b that is flat in cross section and approximately parallel to the main portion 26
have. The inner line electrode 22 passes through the side edge protrusion 27 located on the opposite side of the side edge protrusion 27 of the outer line electrode 23 with respect to the overlapped part 21. During welding, the side edge protrusion 27 of the overlapped part 21 The end surface 7 is a sloped surface 27
On the part of the main part 26 near a or on the protruding surface 27a
The can body preform 19 is fed between the electrode rolls 24, 25 so as to be located above it. As shown in FIG. 6, the material near the end surface 7 of the mano seam welding extends outward in the circumferential direction and flows along the sloped surface 27a.
Further, as shown in the figure, the water flows along the protrusion surface 27b. Therefore, the upper step portion 5a has a shape corresponding to the slope surface 27a.
, 6a and a shelf 8 formed in contact with the protrusion surface 27b.
, 9 is formed.

When the welding current value is relatively high and/or the welding pressure is relatively high, shelves 8, 9 are formed along the entire length of the weld, as in the weld 2 shown in FIG. When the welding current value is relatively low and/or the welding force is relatively low, the shelf portion 18 is
tend to form intermittently along the weld.

Furthermore, if a wire electrode having the above-mentioned type of cross-sectional profile is used, even in the case of a surface-treated steel sheet having a surface treatment layer with relatively high electrical insulation properties, such as tin-free steel,
Even without removing the surface treatment layer from the edge to be welded, it is possible to form a welded part that has a practically satisfactory welding strength and has substantially less spatter and the like. However, in this case, it is preferable to coat the wire electrode with a low-melting metal such as tin in order to prevent pitting-like erosion from occurring on the surface of the weld.

The present invention is not limited to the above embodiments,
For example, depending on the purpose of the can body, a welded can body may be formed in which a stepped portion having a shelf is formed only on the inner surface side of the welded portion or only on the outer surface side of the welded portion. When manufacturing this type of welded can body, a normal wire electrode with a flat overall width is brought into contact with the surface of the overlapping portion on the step side that does not have a shelf.

(Specific example) Thickness 0.20 ta= , amount of metal chromium 120 mg/
m2 metal chromium layer and chromium oxide amount 18mg/
From a tin-free steel blank having a surface treatment layer such as a hydrated chromium oxide layer of m2 (metal chromium equivalent), the inner diameter is 52 + 1 JR1 and the overlap width is 0.2 mm without removing the surface treatment layer from the vicinity of the overlap. 4 darkness, height 13
Six can body preforms were formed.

The overlapping portions of the can body preforms were mano-seam-welded in a nitrogen gas atmosphere using wire electrodes 22 and 23 having a cross-sectional profile of the type shown in FIG.

The line electrode 23.22 has a total width of 1.8 tan, and a height d (seventh
) is 0.04 mm, the radius of curvature r of the inwardly concave slope surface 27a is 0.20 try, the slope angle θ is 27 degrees, and it is made of tin-plated copper wire with a thickness of 6 El/m2. It is something.

The can body preform 19 is fed between the electrode rolls so that the end surface 7 of the overlapping portion 21 is located on the slope surface 27a, and welding is performed at a welding speed of 55 rrV/min as shown in Table 1. By performing welding by changing the current and welding pressure,
Welded can bodies with Nσ of 2 to 5 were produced. Note that sample N. ,l
The can body has a bare wire electrode with a flat surface over its entire width, a thickness of 0.20 + a, and a tin plating of ft 2.8: f//m.
It was produced by welding in the same manner as above, except that a tin-plated steel plate was used.

Epoquinphenol paint with a solid content of 20% by weight was applied to the inner surface of each welded can body using a scraping method, dried (dry film thickness 15 μrn), and then canned to examine the discoloration of the contents and the appearance of iron elution. Evaluation was made as shown in the notes in Table 1. The results are shown in Table 1.

In addition, a metallurgical microscope photograph (magnification 30) and a cross-sectional metallurgical microscope photograph (magnification 120; 5%
Corrosion caused by picric acid alcohol solution is shown in FIGS. 8 and 9, respectively.

N again. , 1 inner metallurgical micrograph (magnification 30) and cross-sectional metallurgical micrograph (magnification 120) of the welded part 32 of the can body 1;
Corrosion with 5% picric acid alcohol solution) is shown in FIGS. 10 and 11, respectively.

(Effects of the Invention) The pine seam welded can body of the present invention has the effect that the repairability of the welded portion with paint is improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a welded can body in the vicinity of the welded part according to the first embodiment of the present invention, FIG. 2 is a longitudinal sectional view taken along the line Il-■ in FIG. 1, and FIG. A plan view near the welded part of a welded can body according to the second embodiment, FIG. 4 is a longitudinal sectional view taken along line IV-IV in FIG. 3, and FIGS. 5 and 6 are a welded can body of the present invention. FIG. 5 is a diagram showing a state just before welding is performed, FIG. 6 is a diagram showing a state immediately after welding, and FIG. 7 is a diagram showing a state immediately after welding is completed, and FIG. 8 and 9 are surface metallurgical micrographs of the welded part of the welded can body according to the embodiment of the present invention, and FIG. 9 is the IX of FIG. 8. Figure 10 is a metal microscopic photograph of the surface of the welded part of a welded can body as a comparative example; Figure 11 is a vertical cross-sectional metallographic photograph taken along line XI-M in Figure 10. This is a microscopic photograph. 1... Welded can body, 2, 12... Welded part, 3, 4...
・Welding main surface, 5, 6.15... Step part, 8.9.18
...Shelf section. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 9 Figure 11 Procedure Amendment Document March 30, 1988 Patent Application No. 117081 2 Invention Name Matsushi seam welded can body 3 Relationship with the case of the person making the amendment Patent applicant address 1-3-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo Name (3
76) Toyo Seikan Co., Ltd. Representative Yoshi Takasaki Department 4 Deputy Director 248 Address 2-14-13 Nishi-Kamakura, Kamakura City, Kanagawa Prefecture Hirowa 0467-
31-6092 i Contents of the amendment in the "Detailed Description of the Invention" column of the specification subject to the amendment Steel (the thickness of the chromium oxide layer is usually 10 to zs in terms of metal chromium)
m9/m)J. (2) Add the following sentence between lines 11 and 12. ``In the case of special tin-free steels whose surface-treated membranes have relatively low electrical insulation (contact resistance), wire electrodes with a cross-sectional profile of the above type may be left bare (i.e. coated with a low-melting metal such as tin). Even if the steel is used without chromium oxidation, it is possible to form a weld with satisfactory weld strength without producing pitting or splash.This type of special tin-free steel is The thickness of the material layer is approximately 2 to 8 my/m in terms of metallic chromium.
Tin-free steel or metal chrome layer with many microscopic protrusions (for example, the base diameter is 5 to 11,000 nm).
Examples include tin-free steel in which a chromium oxide layer has a density of I×10 11 to 1×10 14 pieces/m 2 and a chromium oxide layer thickness of about 3 to 25 μm/m 2 in terms of metal chromium. ”

Claims (1)

[Claims] (1) A mash seam welded can body characterized in that, on at least one side of the welded part, a stepped part having a shelf part substantially parallel to the main surface of the weld is repeatedly formed in a substantially regular manner in the welding direction.