JPH0789286A - Method for manufacturing metal ball-pen tip - Google Patents

Abstract

PURPOSE:To simply, efficiently manufacture a product having high coaxiality by installing rodlike metal materials in inner holes having a small-diameter part and a large-diameter part of forging molds, pressing it to form a small- diameter part and a large-diameter part, and using the small-diameter part as an ink tank, etc. CONSTITUTION:In order to manufacture a metal ballpoint pen tip by cold forging a profile, a metal material 1 wound in a coil state is first sequentially passed through a movable winding trend forcing roll 2 and a fixed die 3, and then cut in a suitable length by a shearing die 4. The cut material 5 is installed in an inner hole 7 of forging molds 6. That is, after the material 5 is inserted from an opening 12 of a large-diameter part 9 side of the hole 7 to be installed, it is pressed by a punch 13 to form a large-diameter part 14 and a small- diameter art 15. On the other hand, a protruding pin 11 is inserted from an opening 10 of a small-diameter part side of the hole 7. Thus, the part 14 is used as a press-in connecting part of an ink tank or an ink tank and nap holder.

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 ball-pen tip whose outer shape is formed by cold forging. Here, cold forging refers to forging performed at a temperature equal to or lower than the recrystallization temperature of the material to be forged.

[0002]

2. Description of the Related Art Conventionally, it is known that a ball pen tip formed of a metal material such as brass, nickel silver and stainless steel is formed by cold forging. here,
When the target ball-pen tip outer shape has a large diameter portion and a small diameter portion, two or more kinds of different diameters of the inner hole of the forging die for installing the material obtained by cutting the metal material wound into a coil into appropriate lengths are installed. A method of forming by using a mold and combining them is performed.

[0003]

In forming the outer shape of the ball-pen tip by using two or more forging dies having different inner hole diameters, there is a problem in the dimensional accuracy of the material after processing.

That is, since a metal material wound in a coil shape is used, a material cut into an appropriate length is
The coaxiality is low (coaxiality: the degree of deviation between the design center line of the rod-shaped member and the actual product center line,
Hereinafter, "high coaxiality" means that the center line of the product is close to the designed center line). This is a curl correction roll when cutting a metal material in a coiled state.
Although he was trying to correct the bend by Lar, it was not enough.

The use of such a material having a low degree of coaxiality causes a number of problems when the ball-pen tip manufactured thereby is assembled as a writing instrument. As an example, in the case where the ink tank is formed of a synthetic resin pipe body and the ball-pen tip is directly press-fitted into this ink tank, the center of the pipe body and the center of the ball-pen tip are pressed during the press-fitting process. There is a problem that the pipe body is bent or the tip of the pipe body is crushed or scraped. If the pipe body bends, it not only becomes defective, but it also interferes with the automation of the assembly work, and if the tip of the pipe body is crushed or scraped off, the ball pen tip and ink tank are connected and -When it became rupen refill, it would lead to defects such as ink leaks, and if it had flowed into the market, it would significantly reduce the credibility of the manufacturer. Further, the same problem occurs in the case where the ball-pen tip is not directly press-fitted into the ink tank but is connected through the ink tank / tip holder.

In the past, in order to solve such a problem, not only dimensional accuracy of each inner hole formed in a plurality of forging dies had to be strictly controlled, but also each forging die was installed. We also had to pay close attention to the position, which was extremely inefficient.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing a metal ball-pen tip whose outer shape is formed by cold forging, in which a forging die having an inner hole having a small diameter portion and a large diameter portion is provided with a coil. A rod-shaped material obtained by cutting the metal material wound in a circular shape to an appropriate length is installed, and a small-diameter portion and a large-diameter portion are formed by applying a pressing force to this cut material from the longitudinal direction. Part is an ink tank, or
A gist is a method of manufacturing a metal ball-pen tip, which is characterized in that a press-fitting connection portion with an ink tank / tip holder is formed.

[0008]

EXAMPLE An example is shown below. A general metal ball-point pen tip is mainly manufactured by the following steps.

As a first step, a step of cutting the metal material wound into a coil into an appropriate length. As a second step, a step of forming the outer shape of the cut metal material. As a third step, a step of forming inner shapes such as a ball chamber as a ball pen tip and an ink passage. As the fourth step, a step of holding the ball in the ball chamber.

The present invention is not limited to the above order of steps, and for example, the outer shape may be formed after forming the inner shape as the ball-pen tip.

As shown in FIG. 1, the metal material 1 wound into a coil passes through a movable curl correction roll 2, passes through a fixed die 3, and is appropriately lengthened by a shearing die 4. To be disconnected.

A rod-shaped metal material 5 cut into an appropriate length
Is installed in the inner hole 7 of the forging die 6 made of cemented carbide, as shown in FIG. The inner hole 7 of the forging die 6 is composed of a small diameter portion 8 and a large diameter portion 9, and an SKS for positioning the material to be forged and taking it out after processing from the opening 10 on the small diameter portion 8 side. A protruding pin 11 made of an alloy steel such as SKD or SKD is inserted.

The rod-shaped metal material 5 is inserted and installed from the opening 12 on the large diameter portion 9 side of the inner hole 7, and the rod-shaped metal material 5 is also SKS or the like from the opening 12 on the large diameter portion 9 side. SK
A large pressure portion 14 and a small diameter portion 15 are formed on the rod-shaped metal material 5 by applying a pressing force with a punch 13 made of an alloy steel such as D. Here, since the small diameter portion 8 and the large diameter portion 9 formed in the inner hole 7 of the forging die 6 are originally formed such that the center lines of the respective portions are on the same straight line, the processed metal material 5 The concentricity of the large diameter portion 14 and the small diameter portion 15 formed in the above is naturally high.

At this time, if the diameter of the large diameter portion 9 of the inner hole 7 is made substantially the same as the diameter of the original metal material 1 wound into a coil, the small diameter portion 15 is mainly subjected to plastic deformation. That is the part. Therefore, the surface of the small-diameter portion 15 becomes smooth, and this portion serves as a press-fitting connection portion with the ink tank or the ink tank / chip holder, so that the liquid-tightness in this portion is also improved.

Although the process may be continued as it is, such as a cutting process for forming the inner shape of the ball-pen tip,
In order to further increase the coaxiality, the diameter of the large diameter portion 9 is larger than the diameter of the metal material 1 wound in a coil shape, and the diameter of the small diameter portion 8 is substantially the same as the diameter of the small diameter portion 15 formed on the metal material 5. The large-diameter portion 14 is upset by another forging die that is the same. At this time, the stepped portion formed on the metal material 5 can be made clear from a smooth one, and the difference between the small diameter portion 15 and the large diameter portion 14 can be further increased. In other words, it becomes a ball-point pen tip, and it is possible to suppress variations in press-fit length as much as possible when press-fitting it into a pipe body as an ink tank or an ink tank / chip holder.
Further, in the small-diameter portion 8 of the forging die 6, a taper-shaped reducing portion is formed at a position corresponding to the tip portion of the small-diameter portion 15 of the metal material 5, and an ink tank, or It is also possible to form a press-fitting guide portion for the ink tank / chip holder.

In order to process the above two types of forging processes with one forging die, the small diameter portion 8 of the inner hole 7 of the forging die 6 is made smaller than the diameter of the rod-shaped metal material 5, and The large diameter portion 9 of the inner hole 7 of the forging die 6 is formed into a rod-shaped metal material 5
The diameter may be larger than the diameter. By this processing, the manufacturing cost of the product can be significantly reduced.

Further, as shown in FIG. 3, it is possible to form a protrusion 16 on a portion of the punch 13 that abuts the metal material 5. When a large pressure portion 14 and a small diameter portion 15 are formed on the metal material 5 by applying a pressing force with the punch 13 having the protrusions 16, the concave portion 17 is formed at the tip of the large diameter portion 14 of the deformed metal material. Is formed. The recess 17 becomes a ball holding portion of the ball pen tip by post-processing (cutting or the like). That is, the ball-point pen tip processed by using the punch 13 having the protrusion 16 is one in which work hardening and composition orientation change are positively generated in the state of the material near the ball holding portion. . Therefore, as the ball pen tip, the abrasion resistance of the ball holding portion is improved and the rotation of the ball becomes smooth. Although the reason why the rotation of the ball is smooth is not clear, the orientation of the relatively soft and highly lubricious component elements such as lead and sulfide contained in the metal material is deformed by the projections 16 due to the pressing deformation of the ball pen tip. It is believed that it will appear in a large area when subjected to processing such as cutting when it is compressed in the longitudinal direction and expands in diameter. In particular, the nickel-white material containing lead as a so-called free-cutting component for facilitating the cutting in the metal material, the stainless steel containing manganese sulfide, and the like are more improved in lubricity.

The shape of the projection 16 may be a pyramidal tip or a hemispherical shape in addition to the shape shown in FIG.
The cross-sectional shape may be circular or polygonal. Here, the size of the concave portion 17 formed by the protrusion 16 depends on the size of the completed void.
It does not have to be the same size as the ball holding chamber of the lupen tip. Preferably, the projection 16 has a circular cross-sectional shape, and the diameter thereof is set to be equal to or larger than the diameter of the contact portion between the ball and the ball receiving seat portion. It can be said to be preferable.

Nickel white material (15% nickel, 3% lead, 59 copper)
2 of the present invention and a conventional ball-point pen tip (test product 1) whose outer shape is formed by cutting using a material having a content of 100%.
Ball pen tip (test product 2) formed by the processing shown in Fig. 3 and a ball pen formed by the processing shown in Fig. 3 of the present invention.
Three samples were prepared for each of three pen tips (test product 3), and the amount of ball sinking (the amount of wear of the ball receiving seat) when writing 600 m was measured. The results are shown in Table 1. The ball pen tips of the test products 1 to 3 have substantially the same size and shape, and the structure thereof is shown in FIG. 4, which is a cross-sectional view of a main portion of the ball pen tip described later.

Processing of Test Product 1 A coil material finished to the same outer diameter (about 2.3 mm) as the maximum outer diameter of the ball-pen tip by cold drawing is sheared to a predetermined length (about 8.8 mm). ). The columnar material formed by means of the above is machined using a dedicated rear hole (hole on the ink tank side) stage processing machine to finish the ink passage and the reduced diameter portion to a predetermined size. A ball pen tip was obtained by introducing the machined rear hole and reduced diameter portion into a dedicated processing machine and performing precision cutting on the side holding the ball.

Processing of test product 2 A coil material is finished by cold drawing to be about 0.01 mm to 0.05 mm thinner than the maximum outer diameter of the ball-pen tip, and is sheared to a predetermined length. As a forging step, the columnar product formed in step 1 is subjected to a squeezing process to form a reduced diameter portion. As the second step of the forging step, the end portion of the reduced diameter portion is chamfered R and the upset processing is performed so that the ball pen has the maximum outer diameter portion to form a large diameter portion. Insert the molded product into a dedicated processing machine and
The ball pen tip was obtained by cutting the rear hole while cutting the side holding the ball.

Processing of Test Product 3 By cold drawing, a coil material is finished to be thinner by about 0.01 mm to 0.05 mm than the maximum outer diameter of the ball pen tip, and sheared to a predetermined length. As a forging step, the columnar product formed in step 1 is subjected to a squeezing process to form a reduced diameter part and the end part is subjected to a chamfering R process. As the second step of the forging step, upsetting is performed with a punch having protrusions from the side where the ball is held so that the maximum outer diameter portion of the ball pen is reached, and the large diameter portion and A concave portion is formed, and at the same time, finish reduction processing of the reduced diameter portion is performed. Insert the molded product into a dedicated processing machine and
Cutting the side that holds the tool and cutting the post hole.
I got a rupen tip.

[0023]

[Table 1] Writing test conditions Writing distance; 600 m Writing angle; 70 degrees Writing pressure; 100 g Writing direction; Spiral writing test equipment; Seiki Industrial Research Institute Model TS-4
C-10 WRITING TESTER

The ball-point pen tip used in the writing test will be described with reference to FIG. The outer shape basically includes a large-diameter portion 18, a small-diameter portion 19 connected to a rear member (not shown) such as an ink tank, and a taper portion 20.
The tip of the pub 20 is a caulking portion 22 for holding the ball 21. The internal structure has a through hole 23 as an ink passage, and the through hole 23 is a ball holding portion 23 that holds the ball 21 so as to rotatably partially protrude from the tip.
a and a central hole 2 for supplying ink to the ball holding portion 23a
3b and the radial groove 23c. Ball holding room 2
The ball 3a comes into contact with the ball 3a during writing and the central hole 23b.
The ball receiving seat portion 23d is provided as a portion for opening the ink supply from the radial grooves 23c. When the ball is rotated by writing, the writing pressure and the rotating force are received by the ball receiving seat portion 23d, and the ball receiving seat portion 23d is gradually worn. The abrasion of the ball receiving seat portion 23d means that the contact area between the ball 21 and the ball receiving seat portion 23d increases, and the ink passage is correspondingly increased in volume.
This is not preferable from the viewpoint of supplying fresh ink to the handwriting because the ink will be blocked by the ink 21 (even if it is blocked, there is no ink at all).

Other than the above, various modifications can be made without departing from the gist of the present invention. For example, the coiled metal material 1 may be in the shape of a pipe, or its surface condition (including the surface condition of the inner hole in the case of a pipe material) may be somewhat rough. good.

Further, in the outer surface shape of the ball-pen tip, a taper-shaped portion whose diameter decreases toward the tip of the ball-pen tip may be formed by forging or cutting. Other parts such as the part for caulking the ball, the inner shape of the ball chamber, the ink passage, the ink flow groove, etc. can be appropriately formed.

[0027]

As described above, the method for producing a metal ball-point pen tip of the present invention is a method for producing a metal ball-point pen tip whose outer shape is formed by cold forging.
A metal material wound in a coil shape was installed as a rod-shaped material cut to an appropriate length in a forging die having an inner hole consisting of a small-diameter portion and a large-diameter portion, and this cutting material was pressed in the longitudinal direction. A small diameter portion and a large diameter portion are formed by applying pressure, and since this small diameter portion is used as a press-fitting connection portion with the ink tank or the ink tank / chip holder, it is coaxial even if dimensional accuracy is not strictly controlled. Since it is possible to provide high-quality products, the work efficiency is high.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing one manufacturing process of a ball-pen tip.

FIG. 2 is a process explanatory view showing one manufacturing process of the ball-pen tip.

FIG. 3 is a process explanatory view showing another manufacturing process of the ball-point pen tip.

FIG. 4 is a cross-sectional view of essential parts showing a ball-point pen tip used in a test.

[Explanation of symbols]

 1 Metallic material wound into a coil 2 Movable curl correction roll 3 Fixed die 4 Shearing die 5 Rod-shaped metallic material 6 Forging die 7 Inner hole 8 Small diameter part 9 Large diameter part 10 Opening 11 Protruding Pin 12 Opening 13 Punch 14 Large diameter 15 Small diameter 16 Protrusion 17 Recess 18 Large diameter 19 Small diameter 20 Taper 21 Ball 22 Caulking 23 Through hole 23a Ball holding 23b Center hole 23c Radial groove 23d Ball receiving seat

Claims (3)

[Claims] 1. A method of manufacturing a metal ball-pen tip having an outer shape formed by cold forging, wherein a metal material wound in a coil shape in a forging die having an inner hole having a small diameter portion and a large diameter portion. Install a rod-shaped material obtained by cutting into a suitable length, and apply a pressing force from the longitudinal direction to this cutting material to form a small diameter part and a large diameter part, and the small diameter part is an ink tank or ink. Metal board characterized by forming a press-fit connection with a tank / chip holder
Lupen tip manufacturing method. 2. The method for producing a metal ball-point pen tip according to claim 1, wherein the small diameter portion of the inner hole of the forging die is made substantially the same as the diameter of the rod-shaped material. 3. The small diameter portion of the inner hole of the forging die is smaller than the diameter of the rod-shaped material, and the large diameter portion of the inner hole of the forging die is larger than the diameter of the rod-shaped material. 2. The method for manufacturing a metal ball-point pen tip according to claim 1, wherein the diameter is the diameter.