JP2017114086A - Manufacturing method for pipe type ball-point pen chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a pipe type ball-point pen chip that can surely avoid a center of a ball from coming off from a shaft center of a metal cylindrical body during a hammering process and during writing, and achieve uniform rotation of the ball and a uniform ink discharge characteristic during writing.SOLUTION: The manufacturing method for a pipe type ball-point pen chip comprises: a ball receiving seat forming step of forming a plurality of inward protruding parts 23 on an inner peripheral surface near a tip of a metal cylindrical body 2; a caulking step of forming a caulking part 22 by inserting a ball 3 into a front side of the inward protruding part 23 and folding inward a tapered edge part 21 at a tip of the metal cylindrical body 2 circumferentially; and a hammering step of pressing the ball 3 rearward with a hammer 4 to press the ball 3 against respective front sides of the inward protruding parts 23. Before the hammering step, on inner surfaces of the metal cylindrical body 2 near respective front base end parts of the inward protruding parts 23 are previously formed raised parts 23b. In the hammering step, the raised parts 23b restrict movement in a radial direction of the ball 3.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for manufacturing a pipe-type ballpoint pen tip. More specifically, the present invention relates to a method of manufacturing a pipe-type ballpoint pen tip in which a plurality of inwardly protruding portions for ball receiving seats are formed on the inner peripheral surface in the vicinity of the tip of a metal cylinder by pressing and deforming radially inward.

In Patent Document 1, a ball receiving seat forming step of forming a plurality of inwardly projecting portions for a ball receiving seat on an inner peripheral surface near the tip of a metal cylinder, and after the ball receiving seat forming step, A caulking process for forming a caulking part by inserting a ball into the front end opening of the metal cylinder on the front side of the side projection and bending the tapered edge part at the front end of the metal cylinder inwardly Then, after the caulking step, the ball is pressed backward with a hammer, and the ball is pressed against the front surface of each inward protruding portion, thereby securing a clearance in the front-rear direction between the inner peripheral surface of the caulking portion and the ball during writing. Before the hammering step, a temporary protrusion is formed in front of each inwardly projecting portion, and the temporary protrusion is pushed backward by the hammer in the hammering step. Crush with a ball A pipe-type ballpoint pen tip manufacturing method, characterized in that, before the hammering step, each of the temporary protrusions is formed on a virtual circle centered on the axis of a metal cylinder. A method for manufacturing a pipe-type ballpoint pen tip is described.

JP2015-66929A

In the manufacturing method of the pipe-type ballpoint pen tip of Patent Document 1, each temporary protrusion is crushed with a ball in the hammering step, so that each temporary protrusion is formed in the middle portion of the front surface of the inward protruding portion. . Therefore, in the hammering process, the center of the ball may come off from the axis of the metal cylinder. In that case, the manufactured ball-point pen tip is formed so that the center of the ball receiving seat (the spherical concave portion formed on the front surface of each inward protruding portion) deviates from the axis of the metal cylinder. There is a risk that uniform rotation of the ball and uniform ink ejection properties cannot be obtained.

Further, in the manufacturing method of the pipe-type ballpoint pen tip of Patent Document 1, even if the center of the ball receiving seat and the axis of the metal cylinder are properly aligned after the hammering step, the ballpoint pen When the tip axis is tilted from the vertical direction with respect to the paper surface, the center of the ball may deviate from the axis of the metal cylinder, which may cause uneven ball rotation and ink ejection during writing. There is.

The present invention solves the above-mentioned conventional problems, and reliably avoids the center of the ball from detaching from the axis of the metal cylinder during the hammering process and during writing. It is an object of the present invention to provide a method for manufacturing a pipe-type ballpoint pen tip that can obtain a rotation and uniform ink discharge performance.

In the present invention, “front” in the ballpoint pen tip indicates the ball side, and “rear” indicates the opposite side. In the present invention, “front” in the pressing pin refers to the tip surface, and “rear” refers to the opposite side.

The first invention of the present application includes a ball receiving seat forming step of forming a plurality of inwardly projecting portions 23 for a ball receiving seat on the inner peripheral surface near the tip of the metal cylinder 2, and the ball receiving seat forming step. Thereafter, the ball 3 is inserted into the front end opening of the metal cylinder 2 on the front side of the inward projecting portion 23, and the tapered edge portion 21 at the front end of the metal cylinder 2 is bent inwardly in a circumferential shape. Thus, after the caulking step, the ball 3 is pressed backward with the hammer 4 and the ball 3 is pressed against the front surface of each inwardly projecting portion 23, so that the caulking at the time of writing is performed. A pipe-type ballpoint pen tip manufacturing method comprising a hammering step for securing a clearance in the front-rear direction between the inner peripheral surface of the portion 22 and the ball 3. Metal cylinder near the front base end of the To form a raised portion 23b to the second inner surface, with the hammer ring step, the raised portion 23b of the each of which characterized by being obtained by restricting the radial movement of the ball 3.

According to the manufacturing method of the pipe-type ballpoint pen tip of the first invention, the protruding portion is formed on the inner surface of the metal cylinder 2 in the vicinity of the front base end portion of each inward protruding portion 23 before the hammering step. 23b is formed, and in the hammering step, each raised portion 23b regulates the movement of the ball 3 in the radial direction, so that the center of the ball 3 is a metal cylinder during the hammering step and during writing. Thus, it is possible to provide a pipe-type ballpoint pen tip that reliably avoids detachment from the axis 2 and can obtain uniform rotation of the ball 3 and uniform ink ejection during writing.

According to a second invention of the present application, in the method for manufacturing a pipe-type ballpoint pen tip according to the first invention, in the ball receiving seat forming step, the cylindrical outer surface 52 of the pressing pin 5 is connected to the front base of each inward projecting portion 23. By pressing against the vicinity of the end portion, a raised portion 23b having a cylindrical inner surface is formed in the vicinity of the front base end portion of each of the inward protruding portions 23.

According to the method for manufacturing a pipe-type ballpoint pen tip of the second invention, each raised portion 23b has a cylindrical inner surface, and the diameter of a virtual inscribed circle in contact with the inner surface of each raised portion 23b is the same in the front and rear. Therefore, the movement of the ball 3 in the radial direction can be stably regulated during the hammering process and writing.

A third invention of the present application is the pipe-type ballpoint pen tip manufacturing method according to the first invention or the second invention, wherein the conical surface 51 and the conical surface 51 are provided behind the conical surface 51 in the ball seat forming step. And pressing the conical surface 51 of the pressing pin 5 against the front surface of each inwardly projecting portion 23, and simultaneously pressing the cylindrical outer surface 52 into each inwardly projecting portion. 23, the conical concave surface 23a is formed on the front surface of each of the inward projecting portions 23, and the vicinity of the front base end portion of each of the inward projecting portions 23, A raised portion 23b having a cylindrical inner surface connected to the conical concave surface 23a is formed.

According to the manufacturing method of the pipe-type ballpoint pen tip of the third aspect of the invention, the conical concave surface 23a and the raised portion 23b ensure that the center of the ball 3 and the axis of the metal cylinder 2 coincide with each other during the hammering process. Can be made.

According to the manufacturing method of the pipe-type ballpoint pen tip of the present invention, it is possible to reliably avoid the ball center from being detached from the axis of the metal cylinder during the hammering process and during writing, and to rotate the ball uniformly during writing. And uniform ink ejection properties.

It is a principal part longitudinal cross-sectional view which shows the metal cylinder of the state before the ball receiving seat formation process in embodiment of this invention. It is a principal part longitudinal cross-sectional view which shows the ball receiving seat formation process of embodiment of this invention. It is a principal part front view of the press pin used at the ball receiving seat formation process of FIG. It is a principal part longitudinal cross-sectional view which shows the metal cylinder after the ball receiving seat formation process of FIG. It is a top view of the metal cylinder body of FIG. It is a principal part longitudinal cross-sectional view which shows the hammer ring process of embodiment of this invention. It is a principal part longitudinal cross-sectional view which shows the metal cylinder after the hammer ring process of FIG. It is a principal part longitudinal cross-sectional view which shows embodiment of the ball-point pen to which the ball-point pen tip obtained by the manufacturing method of FIG.1 and FIG.7 is applied.

1 to 8 show an embodiment of the present invention. 1 to 7 show an embodiment of a method for manufacturing a pipe-type ballpoint pen tip according to the present invention. FIG. 8 shows an application example of the pipe-type ballpoint pen tip 1 obtained by the manufacturing method of FIGS.

FIG. 1 shows the metal cylinder 2 in a state before the ball receiving seat forming step.
A conical surface is formed on the outer peripheral surface of the tip of the metal cylinder 2. Thereby, a tapered edge portion 21 is formed at the tip of the metal cylinder 2. The said metal cylinder 2 is obtained by austenitic stainless steel, such as SUS304, SUS305, SUS321, for example.

Ball receiving seat forming process FIG. 2 shows a ball receiving seat forming process, and FIG. 3 shows a pressing pin 5 used in the ball receiving seat forming process of FIG. 4 and 5 show a state after the ball seat formation process.

The pressing pin 5 includes a conical surface 51 (front end surface) formed at the front end, a first cylindrical outer surface 52 connected to the rear of the rear end of the conical surface 51, and the first cylindrical outer surface 52. A second columnar outer surface 53 that is connected to the rear end of the first columnar outer surface 52 and has an outer diameter larger than that of the first columnar outer surface 52; and a step that is connected to the rear end of the second columnar outer surface 53 Part 54. The outer diameter of the first cylindrical outer surface 52 is slightly larger than the diameter of the ball 3. The outer diameter of the second cylindrical outer surface 53 is formed slightly smaller than the inner diameter of the tip opening of the metal cylinder 2.
In the present embodiment, the diameter of the adopted ball is 0.3 mm, the inner diameter of the tip of the metal cylinder 2 is 0.32 mm, and the outer surface of the first cylindrical outer surface 52 of the pressing pin 5 is outside. The diameter is 0.305 mm, and the outer diameter of the second cylindrical outer surface 53 of the pressing pin 5 is 0.31 mm.

The punch 6 for forming the inward projecting portion 23 has a conical surface at the tip. The top of the conical surface of the punch 6 is an R curved surface.

In the ball seat forming step, the punch 6 is pressed and deformed radially inward at equal intervals in the circumferential direction at a plurality of locations on the side wall near the tip of the metal cylinder 2 (behind the edge portion 21). A plurality (four) of inward projecting portions 23 are formed on the inner surface in the vicinity of the tip of the metal cylinder 2.

When the inward protruding portion 23 is formed, the conical surface 51 of the pressing pin 5 is pressed against the front surface of each inward protruding portion 23. Thereby, the conical concave surface 23a is formed on the front surface of each inward projecting portion 23 by plastic deformation.

At the same time, the first cylindrical outer surface 52 of the pressing pin 5 is brought into pressure contact with the vicinity of the front base end portion of each inward protruding portion 23. Thereby, the protruding part 23b which has a cylindrical inner surface in the front side base end part of each inward protrusion part 23 is formed by plastic deformation. Each of the conical concave surfaces 23a and the raised portions 23b are continuously provided.
(See Figs. 4 and 5)

-Caulking process A caulking process is performed after the ball receiving seat forming process (not shown). In the caulking step, the ball 3 is inserted and arranged from the front end opening of the metal cylinder 2 on the front surface of the inward projecting portion 23, and then the tapered edge portion 21 is bent inward in a circumferential shape, A caulking portion 22 made of an inward annular protrusion is formed. In the crimping step, the ball 3 is brought into pressure contact with the inner circumferential surface of the crimping portion 22, whereby a curved concave portion having a curvature equivalent to that of the ball 3 is formed on the inner circumferential surface of the crimping portion 22 by plastic deformation.

-Hammering process FIG. 6 shows the hammering process (state immediately before hammering). FIG. 7 shows a state after the hammering step. The hammering process is performed after the caulking process.

In the hammering step, the ball 3 is hit backward by the hammer 4 (the ball 3 is pressed backward by the hammer 4), and the conical concave surface 23a on the front surface of each inward projecting portion 23 has the same curvature as the ball 3. A curved concave portion 23c having a shape is formed by plastic deformation. At the same time, a clearance in the front-rear direction of the ball 3 (that is, a clearance in the front-rear direction between the inner surface of the crimped portion 22 and the ball 3 at the time of writing) is ensured. In the hammering step, the movement of the ball in the radial direction is restricted by each raised portion 23b. Thereby, after the said hammering process, the axial center of the curved recessed part 23c formed in the front surface of each inward protrusion part 23 and the axial center of the metal cylinder 2 can be made to correspond.

The pipe-type ballpoint pen tip 1 is obtained by the ball receiving seat forming step, the caulking step, and the hammering step. The pipe-type ballpoint pen tip 1 obtained in the present embodiment has a curved concave portion 23c formed on the front surface of each inward protruding portion 23, and is made of a metal near the front base end portion of each inward protruding portion 23. A raised portion 23 b is formed on the inner surface of the cylindrical body 2. Thereby, at the time of writing, the center of the ball 3 coincides with the axial center of the metal cylinder 2, and uniform rotation of the ball and uniform ink discharge property can be obtained.

Ballpoint Pen FIG. 8 shows a ballpoint pen 7 to which the pipe-type ballpoint pen tip 1 obtained by the manufacturing method of the present embodiment is applied.

The ball-point pen of the present embodiment includes a ball-point pen tip 1 that has a ball 3 rotatably held at the tip, a holder 71 in which the rear portion of the ball-three pen tip 1 is press-fitted and fixed to the front portion, and a rear portion of the holder 71 Is composed of an ink containing cylinder 72 press-fitted and fixed to the opening of the tip, and a spring 73 accommodated in the ballpoint pen tip 1 and the holder 71.

Ballpoint pen tip The tip body of the ballpoint pen tip 1 is made of a straight cylindrical metal cylinder 2. A plurality of (for example, four) inward projecting portions 23 (that is, ball receiving seats) are formed at equal intervals in the circumferential direction on the inner surface in the vicinity of the tip of the chip body by inward pressure deformation. Further, a tapered edge portion 21 is formed in advance at the tip of the chip body, and the inward crimping portion 22 is formed by pressing and deforming the edge portion 21 inward in a circumferential shape. A ball 3 is rotatably held between the front surface of the inward projecting portion 23 and the rear surface of the caulking portion 22. Between the inward protruding portions 23, an ink flow gap is formed that extends radially outward from the central portion and penetrates in the axial direction.

Spring In the spring 73, a front rod portion 73a and a rear coil portion 73b are integrally connected. The rod portion 73a of the spring 73 is inserted through the ink circulation gap. The ball 3 is urged directly forward by the rod portion 73 a, whereby the ball 3 is brought into close contact with the inner peripheral surface of the crimping portion 22.

Ink storage cylinder The ink storage cylinder 72 is a cylindrical body that is obtained by extrusion molding of a synthetic resin (for example, polypropylene) and is open at both ends. The ink container 72 is filled with a follower made of ink and a high-viscosity fluid that moves forward as the ink is consumed.

Holder The holder 71 is a cylindrical body obtained by injection molding of synthetic resin (for example, polypropylene). The holder 71 includes a tapered front portion to which the ballpoint pen tip 1 is attached, a collar portion that comes into contact with the front end surface of the ink storage cylinder 72, and a rear portion that is press-fitted into the front end opening of the ink storage cylinder 72. A locking protrusion is formed on the inner surface of the rear portion of the holder 71, and the rear end of the coil portion 73b of the spring 73 is locked to the locking protrusion.

-According to the manufacturing method of the pipe-type ballpoint pen tip of the embodiment of the present invention, before the hammering step, the inner surface of the metal cylinder 2 in the vicinity of the front base end portion of each inward protruding portion 23 in advance. A raised portion 23b is formed, and in the hammering step, each raised portion 23b restricts movement of the ball 3 in the radial direction, so that the center of the ball 3 is made of metal during the hammering step and during writing. It is possible to provide a pipe-type ballpoint pen tip that reliably avoids detachment from the axial center of the cylindrical body 2 and can obtain uniform rotation of the ball 3 and uniform ink ejection during writing.

According to the manufacturing method of the pipe-type ballpoint pen tip of the present embodiment, in the ball receiving seat forming step, the cylindrical outer surface 52 of the pressing pin 5 is pressed against the vicinity of the front base end portion of each inward protruding portion 23. By forming the bulging portion 23b having a cylindrical inner surface in the vicinity of the front base end portion of each inward projecting portion 23, each bulging portion 23b has a cylindrical inner surface, and the inner surface of each bulging portion 23b. Since the diameter of the virtual inscribed circle in contact with the front and rear has the same inner diameter, the movement of the ball 3 in the radial direction can be stably regulated during the hammering process and writing.

In the manufacturing method of the pipe-type ballpoint pen tip of the present embodiment, in the ball receiving seat forming step, a conical surface 51 and a columnar outer surface 52 (first columnar outer surface) connected to the rear of the conical surface 51 are provided. The conical surface 51 of the pressing pin 5 is pressed against the front surface of each inward projecting portion 23, and at the same time, the cylindrical outer surface 52 is brought to the front base end portion of each inward projecting portion 23. By pressing against the vicinity, a conical concave surface 23a is formed on the front surface of each of the inward projecting portions 23, and connected to the conical concave surface 23a in the vicinity of the front base end portion of each of the inward projecting portions 23. By forming the raised portion 23b having a cylindrical inner surface, the conical concave surface 23a and the raised portion 23b ensure that the center of the ball 3 and the axis of the metal cylinder 2 coincide with each other during the hammering process. Can be

DESCRIPTION OF SYMBOLS 1 Ball-point pen tip 2 Metal cylinder 21 Edge part 22 Caulking part 23 Inward protrusion part 23a Conical concave surface 23b Raised part 23c Curved concave part 4 Hammer 5 Press pin 51 Conical surface 52 First cylindrical outer surface 53 Second circle Columnar outer surface 54 Step part 6 Punch 7 Ballpoint pen 71 Holder 72 Ink storage cylinder 73 Spring 73a Rod part 73b Coil part

Claims (3)

A ball receiving seat forming step for forming a plurality of inwardly projecting portions for the ball receiving seat on the inner peripheral surface near the tip of the metal cylinder;
After the ball receiving seat forming step, the ball is inserted into the front end opening of the metal cylinder on the front side of the inward projecting portion, and the tapered edge at the front end of the metal cylinder is inwardly circular. A caulking process for forming a caulking portion by bending the
A hammer ring that secures a clearance in the front-rear direction between the inner circumferential surface of the caulking portion and the ball during writing by pressing the ball backward with a hammer and pressing the ball against the front surface of each inward protruding portion after the caulking step. A pipe-type ballpoint pen tip manufacturing method comprising:
Before the hammering step, a bulge is formed in advance on the inner surface of the metal cylinder in the vicinity of the front base end of each inward projecting portion, and in the hammering step, each bulge is a diameter of a ball. A method for manufacturing a pipe-type ballpoint pen tip, characterized by restricting movement in a direction. In the ball receiving seat forming step, the cylindrical outer surface of the pressing pin is pressed near the front base end portion of each inwardly projecting portion to be formed, so that the raised portion having the cylindrical inner surface is The method of manufacturing a pipe-type ballpoint pen tip according to claim 1, wherein the pipe-type ballpoint pen tip is formed in the vicinity of the front base end portion of the protruding portion. In the ball receiving seat forming step, a pressing pin having a conical surface and a cylindrical outer surface connected to the rear of the conical surface is used, and the conical surface of the pressing pin is pushed to the front surface of each inward protruding portion. At the same time, the cylindrical outer surface is pressed against the vicinity of the front base end portion of each inward projecting portion, thereby forming a conical concave surface on the front surface of each inward projecting portion and each inward projecting portion. 3. A method for manufacturing a pipe-type ballpoint pen tip according to claim 1 or 2, wherein a raised portion having a cylindrical inner surface connected to the conical concave surface is formed in the vicinity of the front base end portion of the portion.

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