Metal deforming – With 'coating' of work
Reexamination Certificate
2001-05-30
2002-10-15
Larson, Lowell A. (Department: 3725)
Metal deforming
With 'coating' of work
C072S379400
Reexamination Certificate
active
06463776
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a manufacturing method for a bottle-shaped can, of which a can body, a shoulder portion and a neck portion are integrally shaped from a metallic sheet (or a metal sheet), and, more particularly, to a method of manufacturing a bottle can with the outer surface of its body portion or the outer surface of the portion from its body portion to its shoulder portion being decorated with a print or the like.
BACKGROUND ART
As beverage cans for various soft drinks, juice or beer, there are generally employed the two-piece cans, of which the can body (or side wall portion) and the can bottom (or end wall portion) are integrally shaped. The two-piece can of this kind is manufactured by a suitable method such as by drawing and ironing, by drawing/redrawing, or by drawing/redrawing and stretching a metallic sheet such as an aluminum alloy sheet or a surface-treated steel sheet.
In such a two-piece can, there are integrally shaped the can bottom having a domed shape for improving the pressure resistance and the thinned body portion, and the open upper end portion of the body portion side wall is necked in to reduce the diameter and is flanged.
Moreover, the two-piece can is filled with a body such as a juice, soft drinks or beer, and the flanged portion of the open body portion is then seamed and sealed with an easy open can end having a smaller diameter than the external diameter of the body portion so that the can is shipped as a beverage can.
This beverage can is opened by a consumer having purchased it when the consumer pulls a tab fixed on the easy open can end.
As disclosed in WO 81/01259, on the other hand, there is also manufactured a bottomed cylindrical can which is shaped to have a thinner body wall than a bottom wall by drawing and redrawing (or by bending and extending at the redrawing time or by stretching) the surface-treated steel sheet having two sides laminated with a thermoplastic resin film. The can thus manufactured is necked in and flanged like the aforementioned can so that it may be used as the beverage can.
As the containers for soft drinks, juices, teas or coffees, on the other hand, there have been employed in recent years the bi-oriented molded containers (i.e., the PET bottle) made of a polyethylene terephthalate resin. Accordingly, the various soft drinks and others contained in the re-sealable PET bottles are mass-produced and sold by filling the bottles with them and by sealing the bottles with the threaded caps.
These beverage PET bottles have an advantage over the can containers for the beverages in that they can be repeatedly sealed with the caps. However, the PET bottles are in considerably lower states than those of the can containers in the recycling ratio for recovering and recycling the bottles. Therefore, it has been investigated to enhance the conveniences of the can containers by adding to the re-sealing function to the can containers having a high recycling ratio.
As the metallic cans which can be re-sealed with the threaded caps, there are disclosed in Japanese Patent Laid-Open No. 10-509095 (WO96/15865) several types of bottle-shaped drawn/ironed cans (i.e., DI cans) having shapes similar to those of the PET bottles, i.e., the DI cans which have threaded neck portions to be screwed with threaded caps.
These DI cans are classified into: the type in which an end sheet to be seamed on the open upper end of a can body is formed to form a threaded neck portion integrally; the type in which the threaded neck portion is integrally formed by reducing the diameter of the open upper end side of the can body stepwise by the neck-in working (i.e., by making the diameter smaller toward the open end); and the type in which the small diametrical neck portion and the shoulder portion having a slope are formed by drawing the drawn bottom E portion side (or the end wall portion) of a cup at multiple steps, in which the neck portion is then opened and is curled and threaded, in which the body portion of the cup is then drawn and ironed into a thin body portion, and in which a separate bottom end is seamed and fixed on the open end of the body portion on the side opposed to the neck portion.
In the above-specified Laid-Open, moreover, there are disclosed not only the structures of the bottle-shaped cans of the individual types but also their shaping (or forming) methods.
According to the disclosure of Japanese Patent Laid-Open No. 58-47520, on the other hand, at the time of drawing the can body, the bottom portion is drawn into a convex stepped shape, and this convex stepped shape is redrawn at an ironing time, to form a stepped convex portion having a small diametrical cylindrical neck portion and a raised shoulder portion. This neck portion is threaded and is sealed with the threaded cap. After this DI can was filled with a beverage from the end opening of the body portion, this end opening is sealed by seaming and fixing the can end.
In Japanese Patent Laid-Open No. 64-47520, moreover, the following concept is disclosed. By pressing (or drawing) the bottom side of the DI can shaped by the drawing/ironing treatment, there are shaped a small diametrical cylindrical neck portion and a frustoconical shoulder portion. The leading end portion of the neck portion is trimmed, and the lubricant having stuck the inner and outer surfaces of the can is degreased/rinsed. The inner and outer surfaces of the can are conversion coated and dried. After this, a coating for the inner surface is sprayed on the inner surface of the can. After the coating is dried, a print is applied to the outer surface of the body portion of the can. After this printing ink is dried, a can end is seamed and fixed on the open end of the body portion. After this, a threaded cylindrical member of a resin is fitted on the neck portion, or this neck portion is screw-cut.
Of the aforementioned bottle-shaped cans which can be sealed again with the threaded cap, the can of the type in which the threaded neck portion is formed integrally with the end sheet is formed at its body into the DI can or a bottomed can such as the DTRD can (Drawn Thin Redrawn) having been drawn and bent/extended (or stretched) or the can having been drawn and bent/extended (or stretched) and ironed. The can body is filled with a content such as a beverage, and the open end portion of the can body is seamed/fixed and sealed with the end sheet having the threaded neck portion formed integrally therewith.
According to the bottle-shaped can of this type, therefore, the can body has a shape substantially identical to that of the existing general can, and enjoys an advantage that few changes are required in the filling facilities to suppress the cost for the facilities.
In the bottle-shaped can of this type, however, the end sheet seaming portion is located in the upper portion of the can to raise problems that dust is liable to accumulate in the concave portion inside of the seamed portion, and that the seamed portion itself protrudes to deteriorate the appearance.
In the bottle-shaped can of the type in which the neck portion is formed not at the end sheet but integrally at the upper end portion of the can body, on the other hand, the upper end portion is stretched thin and worked hard by a similar working as the can body is drawn and ironed or bent and extended. Considering the later step of working the neck portion, therefore, the upper end portion of the can body is worked so relatively thick as to make the extension of the material less than the lower portion (or as to reduce the work hardening extent).
Since the neck portion has a considerably smaller diameter than that of the can body (or the body portion of the can), however, a diameter reduction ratio for forming the neck portion is so large as to make it necessary to make a diameter reduction work many times.
When the number of the diameter reduction work is reduced by enlarging one drawing rate, on the other hand, the can body is wrinkled or cracked at its upper end portion.
In order that a small cap may be used to lower the c
Enoki Yasushi
Ogawa Yukio
Shima Yoshinao
Tamiya Hirotomo
Daiwa Can Company
Larson Lowell A.
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