JPH05123799A - Production of metallic box body - Google Patents

Abstract

PURPOSE:To enable the efficient production of a square cylindrical shape which constitutes a barrel part and the mass production of box bodies under good productivity by joining both ends of a plate material to form a cylindrical body, then subjecting this body to press forming. CONSTITUTION:Bending deformation in the angle parts at four corners and surface working for working the arc surfaces of four faces to planes are needed to form the cylindrical body 3 to a square cylindrical body 6. Sharp-angled corner working parts 11 are formed in the molding space formed of a mold 4 and a plunger die 5 for this purpose. Further, a square pressing tool 12 is utilized so as to press the cylindrical body 3 from the inner side toward the corner working parts 11. Reverse strains are applied to the four faces enclosing the molding space so as to form these faces to projecting surfaces 13 projecting to the inner side and to form the planes. The square cylindrical body 6 is thus molded. Then, the square cylindrical body 6 is formed extremely efficiently and the box body 9 is obtd. simply by joining a bottom plate 7 to one end thereof. The box bodies 9 are thus inexpensively mass produced with the good productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal box body which can be suitably used as an inner box or an outer box of a rectangular vacuum heat insulating container.

[0002]

2. Description of the Related Art As shown in FIG. 4, a generally rectangular vacuum heat insulating container 21 has a surface composed of an inner box 23, an outer box 24 and an end material 25 for holding the vacuum of a vacuum heat insulating layer 22. They are joined together to form an airtight double structure. The inner box 23, the outer box 24, and the end material 25 are formed of a thin metal plate material such as stainless steel, which has excellent material strength and can be plastically worked.

The inner box 23 and the outer box 24 as described above are manufactured by welding the side plates or the side plates and the flat plate forming the bottom plate to each other at their side edge portions.

[0004]

However, such a manufacturing method has a problem that it is not suitable for mass production because the welding line is long and the welding requires a lot of time and cost.

By the way, each of the inner box 23 and the outer box 24 of the vacuum heat insulating container 21 described above can be constructed by joining a bottom plate 27 to a barrel-shaped body portion 26 as shown in FIG. .. Therefore, if this rectangular tubular body 26 can be mass-produced, the inner box 23 and the outer box 24 can be manufactured very efficiently only by joining the body 26 and the bottom plate 27. ..

[0006] Therefore, the present invention provides a method for manufacturing a metal box body capable of efficiently manufacturing a rectangular tube body as a body portion and mass-producing boxes with good productivity. With the goal.

[0007]

In order to achieve the above-mentioned object, according to the present invention, both ends of a plate material are joined to form a cylindrical body, and the cylindrical body is arranged in a mold having a rectangular molding space. The base plate is press-molded into a rectangular tube shape, and the bottom plate is joined to the opening on one end side of the molded rectangular tube body.

[0008]

In this way, it is possible to efficiently form a rectangular cylinder by joining both ends of the plate material to form a cylinder and then press-molding the cylinder. Therefore, a desired box body can be obtained only by joining the bottom plate to one end of this rectangular tube body.

[0009]

EXAMPLE As shown in FIG. 1, first, a plate material 1 having a length equal to the perimeter of the body of a box to be manufactured and a width equal to the height was prepared (step (a)), and this plate material was prepared. Both ends of 1 are joined to each other at welded portions 2 to form a cylindrical body 3 (step (b)). Next, the cylindrical body 3 is put into a mold 4 having a rectangular molding space (step (c)) and press-molded with a pressing die 5 to form a rectangular tube body 6 (step (d)). ). Finally, the bottom plate 7 is attached to one end of the formed rectangular tubular body 6.
The box body 9 is manufactured by joining the tongues at the welded portion 8 (step (e)).

In the above-mentioned press forming step, in order to form the cylindrical body 3 into the rectangular cylindrical body 6, the bending deformation of the corners of the four corners and the flattening for machining the four arc surfaces into flat surfaces are required. is necessary. Therefore, as shown in detail in FIG. 2, in the molding space formed by the die 4 and the pressing die 5, sharp corner-shaped corner processing portions 11 are formed at the four corners thereof. Further, the corner pressing tool 12 is used to press the cylindrical body 3 from the inside toward the corner processing portion 11. Further, four surfaces surrounding the molding space are formed on the convex curved surface 13 projecting inward to give reverse distortion for forming a flat surface.

In this way, the rectangular tubular body 6 is formed.
The thickness of the plate 1 is 3 mm because the corners of the four corners have a high degree of processing.
It is appropriate that the degree is not more than that. In that case, the radius of curvature of the inner corner is approximately equal to the plate thickness.

As shown in FIG. 1, when the cylindrical body 3 is put into the mold 4 in its original shape, the length L of one side of the rectangular cylindrical body 6 to be molded is equal to the diameter D of the cylindrical body 3, or It becomes larger than that, and the length M of the other side becomes smaller than L. Therefore, in that case, the rectangular tubular body 6 having a rectangular cross section is used.
Is manufactured. That is, assuming that the diameter of the cylindrical body 3 is D, the length of one side of the rectangular tubular body 6 is L, and the length of the other side is M, L ≧ D M ≦ D · (π−2) / 2≈0. The relationship of 57D 1 is established, and the rectangular tubular body 6 whose longer side is longer than the ratio of L: M = 1: 0.57 can be manufactured.

On the other hand, when the square-shaped rectangular tubular body 6 of L: M = 1: 1 is molded, as shown in FIG. 3, first, the cylindrical body 3 is molded as in the previous case (step (a)). ), The cylindrical body 3 is pressed from both sides to form an elliptic cylinder 14 having d = πD / 4, and the elliptic cylinder 14 is put into a mold 4 having a width W = d (step (c)) and pressed. Press molding is performed with the mold 5. As a result, the square prismatic body 6 having L = M = d = πD / 4 is obtained.

[0014]

As described above, according to the present invention, by joining both ends of a plate material to form a cylindrical body and then press-molding the cylindrical body, a rectangular cylindrical body can be formed extremely efficiently. Since the box body can be obtained simply by joining the bottom plate to the box body, the box body can be mass-produced with good productivity and at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a rectangular tube body according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing details of a main part of a forming process of the rectangular tubular body in FIG.

FIG. 3 is a diagram showing a manufacturing process of a square tubular body having a square cross section according to the present invention.

FIG. 4 is a perspective view showing a conventional vacuum heat insulating container with a part cut away.

FIG. 5 is an exploded perspective view of a rectangular tube body and a bottom plate for a box body manufactured according to the present invention.

[Explanation of symbols]

 1 Plate Material 2 Welding Part 3 Cylindrical Body 4 Mold 6 Square Tubular Body 7 Bottom Plate 8 Welding Part 9 Box

Claims (1)

[Claims] 1. A cylinder is formed by joining both ends of a plate material,
A metal box characterized in that the cylindrical body is placed in a mold having a rectangular molding space, press-molded into a rectangular tube, and a bottom plate is joined to an opening on one end side of the molded rectangular tube. Body manufacturing method.