JPS6341756B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a ballpoint pen tip,
In particular, the present invention relates to a method of manufacturing a ballpoint pen tip that is formed from a thin metal tube to improve durability and allows the ink supply path to be designed freely without being restricted by the diameter of the ball.

A method for manufacturing a ballpoint pen tip from a metal thin tube involves pressing inward at multiple locations on the same peripheral edge of the outer peripheral surface near the tip of the metal thin tube to form a protruding seat for the ball on the inner wall. Some methods involve caulking the tip edge of the metal tube after inserting it into the tip.

However, according to this conventional method, since the inner diameter of the metal capillary tube is required to be slightly larger than the ball diameter, the size of the ink supply wick is also limited to the inner diameter dimension of the metal capillary tube. Therefore, sufficient ink cannot be supplied to the chip, which is particularly inconvenient when providing water-based ballpoint pens and the like.

Therefore, the present invention was created to solve the above-mentioned disadvantages, secure a sufficient amount of ink supply, and provide a highly durable and high-quality ballpoint pen tip. The tip of the thin tube is pressed inward over its entire circumference to form a narrowed portion that gradually narrows toward the tip, and this narrowed portion extends from the tip to the vicinity thereof.
The inner diameter of the through hole is smaller than the ball, and the outer diameter is also larger than the ball diameter so that it is thicker than the thickness of the thin metal tube before processing, and the inner wall of this narrowed part is used as the tip opening. A ball holding section is formed by cleaning the cut hole from the direction to form a ball holding cylinder part and a ball pedestal part, and a groove for introducing ink is formed in the ball pedestal part along the through hole, and a ball holding part is formed by cleaning the cut hole from the direction. After the ball is inserted into the holding part, the tip opening edge is caulked to hold the ball in the holding part.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In the figure, reference numeral 1 denotes a metal thin tube, and the tip of one metal tube 1 is pressed inward over its entire circumference and gradually narrows toward the tip, as shown in FIG. form. This narrowed portion 2 extends from the tip to the vicinity thereof, and actually includes at least a ball holding cylinder portion 4 and a ball pedestal portion 5, which will be described later.
The part of the ball holding part 8 consisting of is made into a through hole 6 whose inner diameter is smaller than the diameter of the ball 9, and the outer diameter is also made larger than the diameter of the ball 9 to form the flesh of the thin metal tube 1 before processing. Make it thicker than thick. That is, the narrowed portion 2 is formed by, for example, swaging so that it gradually narrows toward the tip (see FIG. 3).

Next, the inner wall of the narrowed portion 2 that has been narrowed is cleaned from the direction of the rear end opening, and an inlet passage 3 for an ink guiding core (not shown) made of a plastic linear body or the like is expanded ( (See Figure 5). In this case, since the hole is to be cleaned, it is naturally carried out by cutting.

Note that the narrowed portion 2 may be a tapered portion as shown in FIG. 3, or a stepped portion 2A as shown in FIG.
The hole may be formed into a small cylindrical shape through the hole, and in this case, there is no need to carry out hole cleaning from the rear end opening direction.

In the narrowed part 2 formed in this way, a hole is cleaned from the opening direction of the tip in the inner wall of the narrowed part 2 in order to form the ball holding cylinder part 4 and the ball pedestal part 5.
(see figure).

Thereafter, a plurality of ink introduction grooves 7 are formed radially on the hole wall of the through hole 6 of the ball pedestal portion, parallel to the hole core (see FIG. 7).

Through such narrowing, hole clearing, and groove forming, the metal capillary tube 1 has a ball holding portion 8 at its tip. After inserting the ball 9 into the ball holding portion 8, the tip opening edge is bent inward and caulked to obtain a ballpoint pen tip.

The present invention is constructed as described above, and the tip of a single metal thin tube 1 is pressed inward over its entire circumference to form a narrowed portion 2 that gradually narrows toward the tip. This narrowed part 2 has a through hole 6 whose inner diameter is smaller than the diameter of the ball 9 from the tip to the vicinity thereof, and also has an outer diameter larger than the diameter of the ball 9 before machining. Since it is made to be thicker than the thin metal tube 1, a part of the outer peripheral surface near the tip of the thin metal tube is pressed inward to form a pedestal protruding from the inner peripheral wall surface. This eliminates the inconvenience that would occur if the inner diameter of the metal capillary was determined by the ball diameter. That is, the diameter of the metal capillary tube can be selected based on the diameter of the ink guide core depending on the required amount of ink. Furthermore, it is possible to bring the ink guiding core made of a plastic linear body as wide as possible as close as possible to the rear end surface of the ball 9, so that a sufficient and stable supply of ink can be obtained. Furthermore, even if a single metal tube 1 is processed to be narrowed, the extra thickness at the tip is added to the thickness of the tip, making it thicker than the thickness of the metal tube 1 before processing and cleaning the hole described later. Since it is possible to process the material, there is no waste of material.

Then, since the ball holding cylinder part 4 and the ball pedestal part 5 are formed by drilling holes in the inner wall of the narrowed part 2 from the direction of the opening of the tip, the inner surface will be cut, so the inner surface will be formed by plastic working. On the other hand, if you try to achieve the same precision with plastic processing as with cutting, you will need extremely precise molds, which will lead to increased costs. Therefore, the dimensional accuracy of the inner wall surface of the narrowed portion 2, whose outer surface is formed by plastic working, can be improved while using an inexpensive processing process, and a stable supply of ink can be ensured. In addition, the surface condition of the inner wall surface is smooth, so that the ball 9 can roll smoothly, and the writing quality can be improved.

The ball pedestal part 5 has an ink introduction groove 7 and a through hole 6.
Since the ink is formed along the ink guide core, the ink is sufficiently supplied from the ink guide core, and there is no occurrence of ink fading or the like.

In addition, since it is formed from a single thin metal tube 1, it is more durable than ballpoint pen tips made of other synthetic resins.

As explained above, according to the present invention, it is possible to eliminate waste of materials and improve durability, and the ink supply path can be freely designed without being restricted by the ball diameter, thereby achieving stable ink supply. This allows us to provide high quality ballpoint pen tips at low prices.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an overall longitudinal sectional view, FIG. 2 is an enlarged sectional view taken along line A-A in FIG. 1, and FIGS. Figures 3 and 4 are longitudinal sectional views of the main part after narrowing, and Figure 5 shows the state of the thin tube after the hole has been bored from the rear end opening direction. Fig. 6 is a longitudinal cross-sectional view of the main part after the hole has been bored from the direction of the tip opening, and Fig. 7 is a longitudinal cross-section of the main part after the ink introduction hole is formed in the base. It is a diagram. DESCRIPTION OF SYMBOLS 1...Metal thin tube, 2...Narrowed part, 2A...Stepped part, 3...Introduction path, 4...Ball holding cylinder part, 5...
...Ball pedestal, 6...Through hole, 7...Ink introduction groove, 8...Ball holding part, 9...Ball.

Claims (1)

[Claims] 1. A narrowed portion is provided by pressing the tip of a single metal tube inward over its entire circumference so that it gradually narrows toward the tip, and this narrowed portion is
A through hole with an inner diameter smaller than the ball diameter is formed from the tip to its vicinity, and the outer diameter is also larger than the ball diameter so that it is thicker than the wall thickness of the thin metal tube before processing. A ball holding part is formed by cleaning the inner wall of the narrowed part from the direction of the tip opening to form a ball holding cylinder part and a ball pedestal part, and a groove for introducing ink is passed through the ball pedestal part. A method for producing a ballpoint pen tip, which comprises forming a ball along a hole, inserting a ball into a ball holding part, and then caulking the edge of the tip opening to hold the ball in the holding part.