JPS63248519A - Method for forming polygonal bottomed cylindrical body in tapered shape - Google Patents

Abstract

PURPOSE:To form the titled taper-shaped polygonal bottomed cylindrical body in good shape without any wrinkle by inserting into a taper-shaped polygonal outer die the slender bottomed cylindrical body formed by deep drawing a metal plate stock, an inner die in the same shape is press-fitted in and forming it by speading with ironing. CONSTITUTION:A slender bottomed cylindrical body 2 formed by deep drawing a metal plate stock at plural stages is inserted into the taper-shaped polygonal forming hole 8 of an outer die 4. The taper-shaped polygonal inner die 3 in smaller diameter than that of the forming hole 8 is press-fitted into the inner hole of the bottomed cylindrical body 2 and spread by ironing to form a specified tapered polygonal cylindrical body. In that case the bottom face part is kept in good shape because of a knockout pin 6 energized by a spring 9 being pushed down. No wrinkles are caused on the cylindrical face and good external surface is formed because of spreading by ironing.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for forming a tapered polygonal cylinder with a bottom, and is used, for example, as a shaft of a mechanical pencil or a fountain pen. The present invention relates to a method of forming a bottom cylinder into a tapered polygonal cylinder with a bottom.

(Prior Art) The shafts of conventional mechanical pencils and fountain pens have been formed by forming a metal plate into a cylindrical body with a bottom or a cylindrical body with a tapered bottom by deep drawing in multiple steps.

Further, the shaft having a polygonal cross section may be, for example,
A polygonal cylindrical body is formed by drawing or the like, and the opening end is closed with a lid or the like to form a bottomed cylindrical body.

(Problems to be solved by the invention) <Problems with the conventional technology> However, in reality, the designs of current mechanical pencils and fountain pens have diversified, and even the shafts have polygonal cross sections that are difficult to roll. Moreover, there is now a demand for something with an excellent design that has a taper.

However, when forming this tapered polygonal shaft using normal deep drawing, there is a problem that wrinkles form on each side of the polygon, making it impossible to form the shaft.

When we investigate the cause of this, we find that deep drawing is a process in which a cylinder with a bottom that becomes thinner and longer is processed in stages by repeating multiple drawings to form the final elongated cylinder. It is a series of processes to make each piece thinner and longer.

Therefore, if the cross-sectional shape of the bottomed cylinder is circular, the entire body is squeezed uniformly, so there is no equivalent problem, but if the cross-sectional shape is polygonal, the squeezing conditions are different for each corner portion and face portion. Therefore, if it is formed only by conventional deep drawing processing, the corner portions will be drawn to a large extent, resulting in wrinkling on the surface portions. Moreover, in the case of a polygonal cylinder with a bottom that does not have a taper, it may be possible to form it even under this condition because the drawing conditions are somewhat uniform, but in the case of a polygonal cylinder with a tapered bottom, The drawing conditions are different for thin and thick parts, and it can be said that it is almost impossible to perform deep drawing without creating wrinkles on the surface.

On the other hand, in the case of a method in which one open end of the polygonal cylinder is molded with a lid etc. in the cold, it is possible to mold the polygonal cylinder with a bottom without any problems if it is not tapered.
If it is tapered, it must be formed by drawing so that one side becomes slightly thinner. Therefore, wrinkles tend to form on the polygonal surface, and furthermore, the process of bonding the lid and the like is added, resulting in a significant increase in molding cost, which is a major problem.

<Technical Issues> In view of the above-mentioned problems, the present invention enables the forming of a tapered polygonal cylinder with a bottom through a series of plastic workings, and is fully compatible with diversifying designs. It was created with the goal of being able to provide products at low prices.

[Structure of the Invention (Means for Solving Problems) This invention involves forming a metal plate material into an elongated cylinder with a bottom by deep drawing in an appropriate number of steps, and then forming the metal plate into an elongated cylinder with a bottom. The above-mentioned problem is solved by press-fitting a polygonal tapered inner mold to be molded and performing expansion molding, and press-fitting a bottomed cylindrical body into an outer mold to conform to the shape formed by the inner mold. This solves the problem.

(Function) The method for forming a tapered polygonal cylinder with a bottom according to the present invention involves forming a metal plate material into an elongated cylinder with a bottom by deep drawing in an appropriate number of steps, and then inserting the metal plate into the cylinder with a bottom. A tapered polygonal inner mold to be molded is press-fitted and expanded, and a cylindrical body with a bottom is press-fitted into an outer mold so as to have the shape formed by the inner mold, and corner portions and surfaces are molded. The forming of the part is done by spreading and smoothing, and by creating a strained state, the occurrence of wrinkles on the surface part is suppressed.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

That is, the reference numeral 1 shown in FIGS. 1(A) to 1(E) is
It is a material made of metal plate, and is a circular plate material that is processed.

This material 1 is then shown in FIGS. 1(B) and (C).

As shown in (D), (E), and (F), the shaft material 2 of a mechanical pencil, fountain pen, or the like, which is an elongated cylinder with a bottom, is formed by a deep drawing process in which the material is drawn gradually to become thinner. Although not shown in the drawings, the forming die in this case is a conventionally used deep drawing die.

Next, a polygonal tapered inner mold 3 to be molded is press-fitted into the shaft material 2 and expanded molding is performed, and the shaft material 2 is
is press-fitted into the outer mold 4 so as to conform to the shape formed by the inner mold 3, and an expansion and squeezing process is performed.

The mold used in this expansion and ironing process consists of an inner mold 3 and an outer mold 4, as shown in FIG.

The inner mold 3 has a polygonal shape to be molded, for example, a hexagonal cross-sectional shape, and a tapered shape with a tapered tip. Form approximately the same size.

Moreover, the outer mold 4 includes an ironing mold 5, a knockout pin 6,
Knockout board 7 on which this knockout pin 6 is implanted
and a spring 9 which is attached to the ironing die 5 and causes the knockout pin 6 to protrude into the forming hole 8 by its elastic force.

The ironing mold 5 has, for example, a molding hole 8 having a hexagonal cross section that penetrates in the vertical direction, and has a tapered shape in which the inner dimension of the upper opening end is large and the dimension becomes smaller toward the bottom. The tapered portion is formed from the upper opening end to a depth equivalent to the length of the shaft of the mechanical pencil or fountain pen to be molded, or slightly longer than that, so that the bottom of the shaft material 2 is at the deepest point of the tapered portion. The dimensions of the forming hole 8 are set appropriately so that the forming of the shaft is completed when the shaft is forcibly press-fitted to the lower end.

Further, from the lowermost end of the tapered portion to the lower surface of the ironing die 5, a straight sliding hole 10 into which the knockout pin 6 can be inserted is formed. A knockout pin 6 is inserted into the sliding hole 10 from below, and the knockout pin 6 is projected into the forming hole 8 until the knockout substrate 7 comes into contact with the lower end surface of the ironing die 5.

At this time, a spring holding bolt 11 is screwed into the lower surface of the ironing die 5, and the spring 9 is fitted onto the spring holding bolt 11. Further, the spring retaining bolt 11 is disposed so as to pass through the knockout board 7. The spring 9 is fitted between the knockout board 7 and the head of the spring holding bolt 11, and is formed to constantly press the knockout board 7 toward the lower surface of the ironing die 5 by the elastic force of the spring 9. do.

Using the inner mold 3 and outer mold 4 thus formed, the shaft blank 2 described above is expanded and ironed as follows.

That is, as shown in FIG. 2(A), first, the shaft material 2 is inserted into the molding hole 8 of the outer mold 4 with the bottom exposed. Then, since the forming hole 8 is tapered, the bottom corner of the shaft material 2 comes into contact with the tapered surface and stops before it comes into contact with the end surface of the knockout pin 6.

Next, as shown in FIG. 3(B), the inner mold 3 is inserted into the shaft material 2 and pressed downward. Then, until the bottom surface of the shaft material 2 comes into contact with the tip end surface of the knockout pin 6, the bottom part of the shaft material 2 is squeezed by the inner mold 3 and the outer mold 4, which are press-fitted into the shaft material 2 to the bottom. , at the same time,
Almost the entire shaft material 2 is expanded by press-fitting the inner mold 3.

At this time, the elastic force of the spring 9 is set to be very large so that the inner mold 3 does not move until it reaches the bottom of the shaft material 2.

After the inner mold 3 reaches the bottom of the shaft material 2, when the inner mold 3 is pressed further downward, the knockout pin 6
is pushed by the inner die 3, and the knockout pin 6 descends to a predetermined position against the elastic force of the spring 9. Then, the shaft material 2 is squeezed by the outer mold 4, and a predetermined tapered hexagonal cylinder with a bottom is formed.

As a result, if the inner mold 3 is simply press-fitted into the shaft material 2 and expanded, the corner portions will be completely formed, but the surface portions will inevitably remain incomplete. Therefore, since the outer mold 4 is used to squeeze, the surface portion is also completely molded, and a tapered hexagonal bottomed cylinder is completed in good condition. Moreover, in this case, since the plastic working is a combination of expansion and squeezing rather than squeezing, the elongation of the plastic working is not concentrated on the surface portion and is smoothed out, so that wrinkles do not occur.

In the drawings, the tapered portion of the hexagonal bottomed cylinder is formed from approximately half way toward the tip, but it goes without saying that the shape is not limited to this.

Moreover, the shape and structure of the inner mold 3 and the outer mold 4 are not limited to the above-mentioned embodiments, and even if they are polygonal,
Needless to say, it is not limited to the hexagonal shape described above.

[Effects of the Invention] This invention configured as described above forms a metal plate material into an elongated bottomed cylinder by deep drawing in an appropriate number of steps, and then molds the material to be formed into this bottomed cylinder. A tapered polygonal inner mold 3 is press-fitted and expanded, and a cylindrical body with a bottom is press-fitted into an outer mold 4 to conform to the shape formed by the inner mold 3, thereby forming a tapered polygonal shape. Since the corner portions and the surface portion of the bottomed cylindrical body are formed by expanding and smoothing to create a squeezed state, it is possible to suppress the occurrence of wrinkles on the surface portion.

That is, if the inner mold 3 is simply press-fitted into the bottomed cylindrical body and expanded, the corner portions will be completely formed, but the surface portion will inevitably remain incomplete. Therefore, since the outer mold 4 is used to squeeze, the surface portion is also completely molded, and a tapered hexagonal bottomed cylinder is completed in good condition. Moreover, in this case, since the plastic working is a combination of expansion and smoothing rather than narrowing, the elongation of the plastic working does not concentrate on the surface portion and is smoothed out, so that wrinkles do not occur.

Therefore, in the past, attempts were made to form a tapered polygonal bottomed cylinder only by plastic working by deep drawing to make the outer dimensions thinner, which resulted in the problem of wrinkles occurring on the polygonal surface. However, this problem can be solved by combining expansion and smoothing, which are completely opposite ideas.

As described above, according to the present invention, it is now possible to form a tapered polygonal cylinder with a bottom, which was previously impossible, by a series of plastic working, and it is fully compatible with diversifying designs. It has various excellent effects, such as being able to provide products at low cost.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; Fig. 1 is a process diagram of the deep drawing process, Fig. 2 is a process diagram showing the expansion ironing process, and Fig. 3 is a mold used in the expansion ironing process. FIG. 1...Material, 2...Shaft material, 3...Inner mold, 4...
・Outer mold, 5... Ironing mold, 6... Knockout pin, 7... Knockout board, 8... Molding hole, 9...
・Spring, 10...Sliding hole, 11...Spring holding bolt. Patent application person 1)
Shintake 1st (C) (D) 3rd Figure

Claims (1)

[Claims] 1. Form a metal plate into an elongated cylinder with a bottom by deep drawing in an appropriate number of steps. Next, press fit a polygonal tapered inner mold to be formed into the cylinder and expand it. A method for forming a tapered polygonal cylinder with a bottom, characterized in that the cylinder with a bottom is press-fitted into an outer mold so as to conform to the shape formed by the inner mold.