JP3248364B2 - Method for manufacturing ballpoint pen tip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Manufacture of a ballpoint pen tip in which a ball serving as a writing member is held in a state of being partially protruded from an inner hole at a reduced diameter portion formed at a tip end by caulking. About the method.

[0002]

2. Description of the Related Art Conventionally, in order to hold a ball of a ball-point pen made of metal such as brass, nickel silver, stainless steel, copper alloy, aluminum alloy, etc., a center hole of the ball-point pen tip and a ball holding chamber have been used. After the internal structure of the ball pen is formed by cutting or the like, a ball is set in the ball holding chamber, and the tip of a ball pen tip is caulked to form a reduced diameter portion to form the ball. There is known a ballpoint pen tip which is held while projecting a part of the ballpoint pen.

Further, Japanese Patent Publication No. 45-28414 discloses a ball-tip in which an electroplating layer projecting inward is formed at the tip of a ball-point pen, and the inner diameter corner of the opening at the tip is formed as a curved portion. It has been disclosed.

[0004]

Ballpoint [0005] Since employing a ball (sphere) as writing member, although it can be said that smoothness of writing feeling utilizing rotation of the ball is a big advantage, Idaku the ball Since the member to be held always has an opening through which the ball protrudes, the corner of the opening is caught on the surface of the writing object, such as a sheet of paper, which hinders the original advantage of the smooth writing feeling. When the tip of the ballpoint pen tip is formed into a curved shape, the tip of the opening can be relatively suppressed from sticking to the surface of the object to be written even when writing with the writing implement inclined. It can be said, however, that if the outer shape is merely smoothed, the inner diameter corner portion of the opening at the end becomes a portion that is caught by the writing surface, and further improvement has been demanded.

Further, in the case where an inwardly protruding electroplating layer is formed at the opening of the tip of the ball pen tip, not only the work becomes complicated, but also the cost is increased when commercializing the product. .

[0006]

That is, according to the present invention, a ball as a writing member is held by a reduced diameter portion formed at the tip end by caulking in a state of partially protruding from an inner hole. In the method for manufacturing a ball-point tip, a first caulking process is performed on a tip portion before the ball is installed in the inner hole to form a reduced-diameter opening smaller than the ball diameter. Then, a ball is press-fitted into the inner hole from the reduced-diameter opening, and the inner diameter corner of the opening at the tip is deformed into a chamfered shape near the maximum diameter of the ball. A ball pen tip manufacturing method characterized in that the tip portion is further subjected to a second caulking process by a rotary caulking tool having a circumferential press-contact portion, and the outer shape of the reduced diameter portion is formed into a curved surface. Make a summary.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a method for manufacturing a ball-point tip according to the present invention will be described in three steps. These are shown in FIGS. 1 to 3, respectively. The process shown in FIG.
FIG. 2 shows the first caulking process before installing the tool, and FIG.
FIG. 3 shows a process of installing the screw 5 in the inner hole 1 and FIG.
FIG. 7 is a sectional view of a main part showing a step of performing a second caulking process after the ball 5 is installed.

As shown in FIG. 1, a ball holding portion 1a made of a cylindrical material having an inner hole 1 formed of a ball holding portion 1a, a center hole 1b, a radial groove 1c, and the like is provided. Before the installation, the tip portion 2 is pressed against the tip end portion 2 by a rotary roll 3 and caulked to form a reduced diameter portion 4 slightly smaller than the diameter of the ball to be installed in the next step. The reduced diameter portion 4 may be formed so that at least the diameter formed by the inner diameter corner portion 4a of the reduced diameter portion 4 is smaller than the diameter of the ball. The diameter formed by 4b may be smaller than the diameter of the ball.

As shown in FIG. 2, a ball 5 as a writing member is provided on the ball holding portion 1a, and the reduced diameter portion 4 is provided on the material having the reduced diameter portion 4 formed in the previous step. 5 is inserted and installed in a press-fit manner so that the maximum diameter portion 5 can get over. The maximum diameter portion of the ball 5 is inserted while deforming the portion of the reduced diameter portion 4 that contacts the ball 5, and as a result, the inner diameter corner portion 4a is formed into a curved surface as if chamfered. .

Here, the outer diameter corner portion 4 is formed by the above-mentioned caulking.
If the diameter formed by b is smaller than the diameter of the ball, the outer diameter corner 4b will also be formed in a curved surface, and it will be caught by the writing surface. It is possible to obtain a product that is difficult to obtain, and furthermore, a processing rate of caulking processing, which is to be described later, forming an outer shape on a curved surface is small, and a product with high dimensional accuracy without burdening the material is obtained. be able to.

As shown in FIG. 3, a second caulking process is performed on the tip of the material on which the ball 5 is installed by a rotary caulking tool 6 having a curved circumferential press-contact portion 6a. At this time, the curvature of the circumferential pressure contact portion 6a of the caulking tool 6 is set such that a curved surface continuous with the curved surface of the portion corresponding to the inner diameter corner portion 4a formed by the above-described processing is formed. Can be obtained without any corners.

In addition to the above, various modifications can be made without departing from the gist of the present invention. For example, ball 5
The when inserting installed in the bore 1, reduced diameter portion 4 Osaekomi the outer surface of the reduced diameter portion 4 can be suppressed from attempting to elastically expanded. In such a case, the inner diameter corner portion 4a can be largely deformed, which can be said to be efficient. Also,
After the ball 5 is installed, the curvature of the ball 5 can be transferred to the ball holding portion 1a by pressing the ball 5 in the direction in which the ball 5 has been hit, thereby improving the seating of the ball.

[0013]

As described above, according to the ball pen tip manufacturing method of the present invention, a ball pen tip having a smooth writing feeling can be easily obtained without obstructing the smoothness of writing which is an essential advantage of the ball pen tip. And it can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is an essential part cross sectional view for explaining a first step.

FIG. 2 is an essential part cross sectional view for explaining a second step.

FIG. 3 is an essential part cross sectional view for explaining a third step;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner hole 1a Ball holding part 1b Center hole 1c Radial groove 2 Tip part 3 Rotating roll 4 Reduced diameter part 4a Inner diameter corner part 4b Outer diameter corner part 5 Ball 6 Caulking tool 6a Circular pressure contact part

Claims (1)

(57) [Claims] A ball pen tip manufacturing method in which a ball as a writing member is held by a reduced diameter portion formed at a tip end by caulking in a state of partially protruding from an inner hole. Prior to installing the ball in the inner hole, a first caulking process is performed on the tip portion to form a reduced diameter opening smaller than the ball diameter. The inner diameter corner of the opening at the tip is deformed into a chamfered shape near the maximum diameter of the ball by inserting the ball in a press-fitting manner, and then a rotary caulking having a curved circumferential pressure contact portion is performed. A boring characterized in that the tip portion is further subjected to a second caulking process with a processing tool, and the outer diameter of the reduced diameter portion is formed into a curved surface.
A method of manufacturing a rupen tip.