JPS6234628A - Manufacture of metallic cap of writing tool - Google Patents

Abstract

PURPOSE:To decrease the number of processes, to generate no return burr, and to make a shape of a chamfered part constant by forming a stepped part having a projecting curved surface on the inner surface part of a cylindrical body by a stepped part of a punch, when forming the cylindrical body, and thereafter, cutting the outside position of the stepped part and forming an aperture end. CONSTITUTION:A metallic material which can be brought easily to a plastic deformation is formed to a cylindrical body 2 by a press work by using a punch 1 having a stepped part 1a whose corner part is a recessed curved surface, on the outside peripheral surface of a necessary position. When forming the cylindrical body 2, simultaneously, a stepped part 2a whose corner part is a projecting curved surface is formed on the inner surface part by the stepped part 1a of the punch 1, and thereafter, the corner part of the cylindrical body 2 is cut vertically in the axial direction, in the stepped part 2a of the projecting curved surface or the outside position of the stepped part, and a cap 3 is completed. In this way, chamfering becomes unnecessary, no return burr is generated, and a shape of the chambered part becomes constant.

Description

[Detailed description of the invention] (industrial field) The present invention relates to a method of manufacturing a metal cap for a writing instrument.

ζPrior art) Conventionally, when the cap of a writing instrument is made of metal such as aluminum, brass, or stainless steel, an appropriate step in the manufacturing process (;
The inner edge of the opening end of the cap is chamfered by Shintsu cutting.

This is done in order to facilitate attachment and detachment to and from the barrel and to damage the barrel surface and reduce ζ2, but it also has the effect of removing burrs that occur when cutting the open end of the cap. A series of manufacturing steps for a conventional general metal cap is as shown in FIG. That is, first, a cylindrical body (5) is pressed using a punch (4) or the like.
) Firstly, the cylindrical body (5) is cut at the opening end position of the cap (aJ), and finally the inner edge of the opening end is chamfered by cutting. , complete the cap (6) ((7) on the drawing shows the chamfered part)
.

If the barrel is finished with paint, the chamfered portion may be rounded with even greater care so that the edges of the chamfered portion do not damage the surface.

(Problems to be Solved by the Invention) In the conventional manufacturing process for metal caps described above, chamfering by cutting must be performed after the cutting process, which is troublesome and may cause burrs to occur in the chamfered portion. There are certain things that need to be processed to prevent burrs from occurring, such as shaft cylinders that have been painted and finished. Therefore, it was impossible to provide high-quality products at low prices.

The present invention solves these problems.

Our aim is to provide inexpensive, high-quality products.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms a cylindrical body by press working using a punch whose outer circumferential surface ζ diagonal portion at a predetermined position has a stepped concave curved surface. At the same time, the stepped portion of the point forms a stepped portion having a convex curved corner on the inner surface of the cylindrical body.

The present invention provides a method of manufacturing a metal cap for a writing instrument, characterized in that the inner step of the cylindrical body or the outer side of the inner step is cut to form an open end.

(Example) Figures 1 and 3 show examples of the present invention. Part enlarged sectional view.

FIG. 3 is an enlarged sectional view of the main parts of the finished product of the second embodiment.

In this embodiment, a cylindrical body ( 2)
and at the same time when forming the cylindrical body (2): 2. On the inner surface of the cylindrical body (2), a step having a convex curved corner is formed by the step part (1a) of the bond f(1). (2a), and then the corners of the cylindrical body (2) are placed at the stepped portion (2a) having a convex curved surface or at a position outside the stepped portion (corresponding to the open end position of the cap). Cut perpendicularly to the axial direction (mouth;
This completes the cap (3).

(Function) That is, in the manufacturing method of the present invention, in the pressing step for forming the cylindrical body (2), at the same time (: Since the stepped portion (2a) with a convex curved corner is formed on the inner surface, the chamfering process that was performed after the cutting process in the conventional manufacturing process is no longer necessary. Since the inner surface is chamfered by the process, the shape of the chamfered part becomes constant without the occurrence of burrs, which was a problem with conventional manufacturing methods. However, according to the manufacturing method of the present invention (-), since the chamfered portion exhibits a convex curved surface from the beginning, there is no need for rounding.

(Effects of the Invention) As described above, the present invention first reduces the number of steps, and second, the chamfered part is finished in a stable shape by plastic processing, but the edges do not form, so it is suitable for painted shafts and resin shafts. This has the effect of making it less likely to be damaged, making it possible to provide inexpensive, high-quality products. Especially when the inner diameter cross section is not circular:
Second, it is very effective because it is difficult to chamfer the entire circumference.

Furthermore, when plating the cap, there are no edges on the inner surface, so the plating does not adhere excessively, and work such as cleaning the inner diameter is not necessary. If it is provided in the back of the hole, it has the effect of eliminating the effects of plating in cases where inner diameter precision is required.

[Brief explanation of the drawing]

Figure 1 and! Figure J3 shows an embodiment of the present invention.
Fig. 1 is a manufacturing process diagram of the first embodiment, and Fig. 2 is an enlarged sectional view of the main part of the cap of the first embodiment. FIG. 3 is an enlarged sectional view of the main part of the cap of the @2 embodiment. Moreover, FIG. 4 is a process diagram of a conventional manufacturing method. +1)...Punch, (1a)...Stepped part of punch, (
2)...Cylindrical body, (2a)...Step part of the tubular body, (
3)...Cap, (4)...Punch, (5)...
・Cylindrical body, (6)... end, (7)... chamfered part, (aJ... open end position.

Claims (1)

[Claims] When forming a cylindrical body by press working using a punch having stepped portions with concave curved corners on the outer peripheral surface at desired positions, the stepped portions of the punch simultaneously form corners on the inner surface of the cylindrical body. manufacturing a metal cap for a writing instrument, characterized in that the tube forms a stepped portion with a convex curved surface, and then the inner stepped portion of the cylindrical body or the outside position of the inner stepped portion is cut to form an open end. Method.