JPS60227983A - Production of welded can body - Google Patents

Abstract

PURPOSE:To form a weld zone having the width equal over the entire length without generating deviation in the overlapped parts by working preliminarily the contact surfaces of the overlapped part in such a way that said faces incline with respect to the electrode surfaces of wire electrodes and that the ends mesh each other. CONSTITUTION:The overlapped part 9 of a can body forming body 8 formed of a metallic blank is so formed that the surfaces 4a and 5a mesh each other in the transverse direction and that the contact surfaces thereof incline in the circumferential direction of the body 8 with respect to the electrode surfaces 12a and 13a. The welded can body having the weld zone satisfactory over the entire length is thus produced without generation of the deviation toward the outside of the circumferential direction in the superposed part 9, more particularly the part near the front end and rear end thereof even if relatively high welding force is exerted thereto in the stage of welding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a welded can body, and more particularly, a method for manufacturing a welded can body by electrical resistance mating seam welding of the overlapping side surfaces of molded can bodies having surface treatment coatings. Regarding.

(Prior Art) Welded can bodies, for example, welded can bodies for storing beer, carbonated drinks, juices, etc., are usually made by overlapping can bodies formed by rolling metal blanks into a cylindrical shape to form overlapping parts. The parts are manufactured by electrical resistance pine seam solid phase welding via wire electrodes using a pair of opposing electrode rolls.

In that case, the metal blank is a low carbon steel plate (so-called blackboard) that does not have a surface treatment coating, or a metal plate that has a surface treatment coating with relatively low electrical resistance, such as an ordinary tin-plated steel plate (bushiki). In such cases, it is possible to relatively easily manufacture a satisfactory welded can body using the above method without causing defects due to splashes of molten metal, etc., and manufacturing of a welded can body made of tin-plated steel plate is commercially successful.

(Problem to be solved by the invention) However, like tin-free steel (electrolytic chromic acid treated steel sheet), a surface treatment coating with relatively high electrical insulation (in this case, a water-containing chromium oxide layer, the thickness of which is usually In the case of a can body molded body formed from a metal blank made of a metal plate having an area of 5 to 30 m97 m2 in terms of metallic chromium,
During welding, it is easy to noticeably generate snow rash, so unless the surface treatment coating layer (in this case, the hydrated chromium oxide layer and metallic chromium layer) in the overlapped area is removed using a milling cutter, etc., a satisfactory welded area cannot be obtained. was not obtained.

Removal of this surface treatment film layer not only impairs the corrosion resistance of the weld zone, but also increases tool costs and process costs due to wear and tear on the cutter, and removes the remaining chips from the contents (
For example, beer may cause problems such as deterioration of flavor.

As a result of various studies on how to counter this, the present inventors have found that by applying a much higher welding force (the width of the overlapping part) than in the case of a can body formed body such as a tin-plated steel plate. It has been found that a tin-free steel can body molded body having an overlapping portion having a surface-treated coating layer can be pine seam welded without significant occurrence of splat.

However, in this case, during welding, the vicinity of the front end and the rear end (the last welded part) of the overlapping part (usually width 0.2 to 1.0 wg), especially the latter, shift outward in the circumferential direction. The weld width of these parts has decreased, and in extreme cases, it has become a butt weld, reducing the weld strength.
7. If ridge/edge processing is performed, a problem arises in that cracks occur. The phenomenon of this shift is presumed to be due to the escape of the material due to the large amount of matte seam due to the strong welding force, which is directed outward in the circumferential direction.

The above-mentioned deviation is relatively unlikely to occur in areas other than the vicinity of the above-mentioned ends, but this is due to the overlapping welding machine that performs the above-mentioned type of welding, such as the one disclosed in Japanese Patent Publication No. 54-26213. A so-called Z bar with a Z-shaped cross section that guides the mating part to the vicinity of the electrode roll inlet, a group of guide rolls surrounding the can body molded body in the vicinity of the electrode roll, and a pair of electrodes arranged so as to be slightly oblique to each other. This is because rolls and other rolls that take measures to prevent slippage are generally used.

Even when this type of welding machine is used, the reason for the deviation in the above-mentioned case, especially near the rear end of the overlapping part, is that when the rear end vicinity passes through the electrode roll (via the wire electrode), the second part and the guide It is assumed that this is due to the loss of the restraining force of the roll group.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention provides a method for combining a metal blank having a surface treatment film and a multi-formed can body molded body in a pair. This is a method for producing a welded can body by solid phase welding electrical resistance pine seams through a wire electrode using an electrode roll of To provide a method for manufacturing a welded can body that can obtain a satisfactory welded part over the entire length while leaving a surface treatment film on the mating part.

(Structure of the Invention) In order to achieve the above object, the present invention provides an overlapping method for forming a can body formed by overlapping opposing first and second ends of a metal blank having a surface treatment film. A method for producing a welded can body by electrical resistance pine seam welding of the overlapping parts via a wire electrode using a pair of opposing electrode rolls, the contact surface of the overlapping part being on the electrode surface of the wire electrode. The first end and the second end are pre-processed without removing the surface treatment coating so that the first end and the second end engage with each other at an angle with respect to the surface. The present invention provides a method for manufacturing a welded can body characterized by the following.

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

(Means for Solving the Problem) In Figures 1 and 2, 1 is a square metal plate blank made of steel, and the opposing first ends are to be the overlapping part. 2 and the second end 3 have grooves 4 and 5 having triangular cross-sections on mutually opposite surfaces, respectively.
is formed by plastic working such as press forming or roll forming. A coating film (including a printed film) is usually formed except for the vicinity of the ends 2 and 3.

6 is a low carbon thin steel plate 70 which is a substrate, and the lower layer is a metal chromium layer (not shown; the thickness is usually 50 to 130 mm) formed on both sides.
4), the upper layer is a surface treatment film (hereinafter referred to as chromium layer) consisting of a hydrated chromium oxide layer (not shown; the thickness is usually 5 to 3011ii'/m2 in terms of metallic chromium).

The widthwise surface 4a of the groove 4 extends slightly diagonally downward, while the widthwise surface 5a of the groove 5 extends slightly diagonally upwardly. Therefore, when the metal blank 1 is rolled to form the can body molded body 8, as shown in FIG.
At the overlapping portion 9 where the first end 2 and the second end 3 are in contact, the widthwise surface 4a of the first end 2 and the widthwise surface 5& of the second end 3 are engaged with each other. , it is difficult to shift outward in the circumferential direction.

Since the grooves 4 and 5 are formed by plastic working rather than cutting, the chromium layer 6 remains on the widthwise surfaces 4a and 5a, although they are slightly destroyed. On the other hand, the surface 4b in the thickness direction of each of the groove portions 4 and 5
And 5b, the low carbon steel of the substrate is exposed like the end faces 2a and 3a.

As shown in FIG. 3, the overlapping portion 9 of the can body molded body 8, which has been formed more than the metal blank 1, is connected to the external line electrode 1 using an external electrode roll 10 and an internal electrode roll 11 facing each other.
2 and internal wire electrode 13 (both wire electrodes 12, 13 are usually made of one continuous copper wire) are electrically resistive pine seam solid phase welded to produce a welded can body. In order to perform pine seam welding, the electrode surfaces 12a and 13a of the wire electrodes 12 and 13 are parallel to each other as shown in the energized area where welding is performed) and beyond the end surfaces 2a+3a in the overlapped portion 9. Extends in the width direction.

(Function) As described above, in the overlapping portion 9, the width direction surfaces 4a and 5a are engaged with each other, and the contact surface 14 is in the circumferential direction of the can body molded body 8 with respect to the electrode surfaces 12a and 13a. is inclined to. Therefore, even if a relatively high welding force (per unit overlap width) is applied during welding, outward sliding in the circumferential direction occurs in the overlap portion 9, especially near its front and rear ends. Therefore, it is possible to manufacture a welded can body having a satisfactory welded portion over the entire length.

(Means for solving the problem) The width of the overlapping portion 9 is set to be as large as possible within the weldable range in order to reduce material costs and to facilitate mating.
It is desirable that the distance be as small as possible, usually 0.2 to 1.0 m. Accordingly, the width W (Fig. 2) of the grooves 4 and 5 is also
It is usually set at 0.2 to 1.0 darkness.

The maximum depth of the grooves 4 and 5, and thus the thickness direction surface 4b.

The height d of the metal blank 1 is equal to the thickness t of the metal blank 1 (usually 0.
15-0.3) is preferably about 1/8-1/4.

1/8! 7. In the case of J-Sai, the inclination angle θ of the width direction surfaces 4a and 5b is too small, resulting in insufficient engagement between the ends, and the effect of preventing the aforementioned slippage during welding is small. Because it will be. On the other hand, if it is larger than 1/4, the degree of processing becomes too large and it becomes easy to break during flange processing. In order to prevent slipping, the angle of inclination should be approximately 3 to 2.
Preferred results are obtained at 0 degrees, more preferably between about 5 and 15 degrees. Of course, from the viewpoint of preventing misalignment, the angle may exceed 20 degrees, but in this case, the degree of processing is too large and the above-mentioned drawbacks are likely to occur.

(Example) FIG. 4 shows a welded portion 15 formed by the method of the present invention.
This is an example of a cross-sectional metallurgical micrograph (magnification: 60; etched with nital). In this case the thickness is 0.22 m
m tin-free steel (metallic chromium layer thickness, 11
00In/n2, the thickness of the hydrated chromium oxide layer is 10"), the width W is 0.4mm,
Grooves 4 and 5 with a maximum depth d of 0.05 degrees and an inclination angle θ of 6 degrees
Blank 1, height 10, formed by Sores processing
A molded can body 8 having a diameter of 2 mm and an outer diameter of 65 mm was produced. As shown in FIG.
A welding force of p 60 kg is applied to the electrode roll 10.11 (usually 40 kg for can bodies made of tin-plated steel sheets with a thickness of 0.22 van and an overlap width of 0.4 am). ~45 kg of welding force is applied) under 36 m
Matsushi seam welding was performed at a speed of /min. In this case, only a small amount of streak lash occurred, and no misalignment of the overlapped portions occurred at all.

(Effects of the Invention) As shown in the figure, the difference in level at the welded portion 15 is extremely small, and therefore the welded portion 15 has the advantage of being extremely easy to repair with a coating film. This is because the welding force is high and the height of the overlapping portion 9 is smaller than twice the blank plate thickness. and the end face 2a where the low carbon steel was exposed.

Most of the portions 2/a and 3/a corresponding to 3a are within the welded portion 15 and are not exposed to the surface. Since the chromium layer 6 remains on most of both surfaces of the welded part 15, although in a partially destroyed form, it has the advantage of good corrosion resistance and good adhesion of the repair coating. .

(Means for Solving the Problem) As shown in FIG. It may also be a blank 21 of the type in which portions 24', 25 are formed.

In this case as well, as shown in FIG.
and the second end 23 are engaged with each other, and the contact surface 27 thereof is inclined with respect to the line electrode surface 12 a r 13 a.
Even when the welding force is high, displacement of both ends 22, 23 is prevented. However, in this case, the level difference in the welded portion becomes larger than in the case of the metal blank 1 shown in FIG. 2. Furthermore, Figure 5,
In FIG. 6, parts with the same reference numerals as in FIGS. 2 and 3 indicate similar parts. This also applies to the case shown in FIG. 7 below.

Like the can body molded body 38 shown in FIG. 7, the second end 33
A groove 35 similar to that in FIG. 2 is formed in the first
A bent portion 34 similar to that shown in FIG. 5 is formed at the end portion 32 of the groove 35, and the inclination angle θ of the groove portion 35 (see FIG. 2) and the bending angle δ of the bent portion 34 (see FIG. 5) may be formed from a metal blank (not shown) having substantially the same dimensions.

In this case as well, the first end 32 and the second end 33 are engaged with each other in the overlapped portion 39, and even when the welding force is high, displacement of both ends 32, 33 is prevented.

The present invention is not limited to the above examples, and for example, the metal blank may be made of iron having a relatively thick hydrated chromium oxide layer on the surface as disclosed in Japanese Patent Application Laid-Open No. 53-23833. It may also be a pan alloy coated steel plate, or an ultra-thin nickel or nickel-tin plated steel plate having a relatively thick chromium oxide layer on its surface.

It goes without saying that the present invention can also be applied to ordinary tin-plated steel sheets.

Further, the corner between the width direction rM4 a (5a) and the thickness direction surface 4 b (5b) of the groove portion 4 (5) may not be sharp as shown in FIG. 2, but may be a metal blank having a curvature. Further, the can body molded body may have a rectangular cylindrical shape with a rounded corner quadrangular cross section.

(Effects of the Invention) According to the present invention, the first end and the second end are engaged with each other in the overlapped portion of the can body formed body, so that welding can be performed under a relatively high welding force. Even when this is done, there is no deviation in the overlapped portion, and it is possible to form a defect-free welded portion having substantially the same width over the entire length.

Although there is a surface treatment coating on the first end and the second end, a relatively high welding force can be applied without causing the above-mentioned deviation, so the electrical insulation properties of the surface treatment coating are comparable. Even when the welding target is high, the occurrence of splash is minimal and a satisfactory weld can be formed, and the surface treatment film remains on the surface of the weld.
It has the advantages of excellent corrosion resistance and adhesion of repair paint.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a first example of a metal blank applied to the present invention, FIG. 2 is an enlarged longitudinal sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a plan view of the metal blank in FIG. A longitudinal cross-sectional view of the principal part showing the state immediately before welding the overlapping parts of the formed can body molded body, and FIG. 4 shows the welded part of the welded can body manufactured from the molded can body shown in FIG. 3. Fig. 5 is an enlarged vertical cross-sectional view of a second example of the metal blank applied to the present invention, Fig. 6 is a multi-formed metal blank similar to that of Fig. 5. FIG. 7 is a longitudinal cross-sectional view of a main part showing a state just before welding the overlapping parts of the formed can body, and FIG. FIG. 3 is a longitudinal cross-sectional view of a main part showing a state just before welding the overlapping portions. 1.21...Metal plate blank, 2,22.32...
First end, 3, 23. 33... Second end, 6...
・Surface treatment film, 8, 28. 38... Can body molded body, 9
．． 29.39... Overlapping portion, lO... External electrode roll, 11... Internal electrode roll, 12... External line electrode, 12a... Electrode surface, 13... Internal line electrode, 13
a... Electrode surface, 14.27... Contact surface. Agent: Patent attorney Yutaka Shuto, 1. '-'1 piece i
Figure 1 ↓ Figure 2 1 Figure 4 Figure 3 Figure $5 Figure 6

Claims (1)

[Claims] (1) Using a pair of opposing electrode rolls, the overlapping part of the can body formed body formed by overlapping the opposing first and second ends of a metal blank having a surface treatment film is In a method for manufacturing a welded can body by electrical resistance pine seam welding via a wire electrode, the contact surface of the overlapping portion is inclined with respect to the electrode surface of the wire electrode, and the first end and Method 0 for manufacturing a welded can body, characterized in that the first end and the second end are processed in advance so that the second ends engage with each other without removing the surface treatment coating.