JPS6144862Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement and creation of ink guide holes in the tip of a ballpoint pen.

Conventionally, in the tip of a ballpoint pen, a ball seat with an ink guide hole bored in the tip cylinder is tightly inserted and fixed, a ball is loosely fitted into one end of the ball seat, and the tip is pushed to the extent that a part of the ball is exposed. It was common to hold the ball by squeezing the tip of the cylinder (for example, devised in Utility Model Publication No. 49-43217). in this case,
The raw material for the ball seat has wear resistance, lubricity, and
The use of highly elastic synthetic resin was thought to be optimal for smooth ball rotation and a soft writing feel (for example, Utility Model 52-10978
issue).

On the other hand, conventional products with such a structure often have the disadvantage that the ink does not flow smoothly, and the ink often smudges, especially when writing at high speed or continuously. Various geometrical improvements have been made due to the shape of the holes themselves.

This invention was created with the aim of eliminating these drawbacks of conventional products, but in order to eliminate the drawbacks, we focused more on the roughness of the ink guide hole than on the shape of the ink guide hole. It is characterized by being created by placing it on the wood itself.

The flow of ink from the ink supply section into the ball chamber is due to the capillary phenomenon caused by the ink guiding holes, and this capillary phenomenon is caused by a combination of two phenomena: the surface tension of the ink and the contact angle. When the contact angle is acute, that is, when the ink wets the ink guide hole, the ink flows into the ball chamber, and when the contact angle is obtuse, that is, when it does not wet, the ink is pushed back toward the supply section. This contact angle differs depending on the material that makes up the ink guide hole, but synthetic resin, which has traditionally been considered the best material for ball seats, has the disadvantage that it is less likely to get wet with ink than metal. was. In addition, synthetic resins have the disadvantage that they tend to cause ion exchange, and ink dirt and the like tend to adhere to the ink guide holes, resulting in ink clogging.

The above drawbacks were particularly noticeable when a water-based ink with low viscosity was used.

In this device, an ink guide hole is provided at the contact point between the metal cylindrical shaft and the synthetic resin ball seat tightly inserted and fixed into it, which allows the smooth rotation of the ball to be unimpeded, and the majority of the inner wall surface of the ink guide hole is made of metal, improving the flow of ink.

By providing the ink guide hole as described above, when processing the ink guide hole, grooves that serve as ink guide holes are provided on the inner peripheral surface of the cylinder shaft to form grooves that communicate with the ink supply cylinder and the ball chamber, respectively. It has the convenience of processing.

In addition, by providing the grooves on the cylinder shaft side, most of the grooves can be made of metal, which improves the flow of ink and prevents ink scum from forming on the synthetic resin material. It is possible to solve the problem of adhesion. Also, since the groove is provided on the contact surface between the cylinder shaft and the ball seat, if the groove is formed on the cylinder shaft side, the opening of this groove is covered by the circumferential side of the ball seat, and the upper and lower ends of the groove are It is possible to make most of the inner wall surface of the groove a metal surface by communicating with the ink supply cylinder and the ball chamber respectively, and the surface facing the ball seat and covering the groove can be especially gold-plated. Alternatively, in the case of applying a metal layer by plating, there is an advantage that the entire inner wall surface of the groove can be easily formed into a metal surface.

Therefore, with this invention, even if a synthetic resin ball seat is used, it is possible to easily form an ink guide hole with a metal inner wall surface, so that the ink does not interfere with the smooth rotation of the ball. This is an extremely practical idea that allows for the creation of a ballpoint pen tip that has a hole for guiding ink with good flow.

Next, an example of this invention will be described.

Embodiment (1) This embodiment is a case in which a groove is formed on the cylinder shaft 1 side, and a ball seat 2 made of synthetic resin that is tightly fitted and fixed to the cylinder shaft 1 connects the cylinder shaft 1 to the ink supply cylinder a and the ball chamber b. The ball 3 is loosely fitted into the ball chamber b,
When forming the tip of the ballpoint pen by constricting the tip 4 of the ball chamber b to such an extent that a part of the ball 3 is exposed from the ball chamber b, the inner circumferential surface of the cylinder shaft 1 that the ball seat 2 comes into contact with is cut. extrusion or pasting, etc.
By forming the groove 6 by an appropriate method, and covering the opening of this groove with the circumferential side of the ball seat 2 so that the upper and lower ends of the groove 6 communicate with the ink supply cylinder a and the ball chamber b, most of the inner wall surface is covered. Ink guide hole 5H with metal surface
Configure.

With the above-mentioned ballpoint pen tip, the ball seat 2 is made of synthetic resin, so the ball 3 rotates well, and most of the ball seat 2 is made of metal, except for a part of the ball seat 2 that covers the groove 6 of the ink guide hole 5H. Ink flow also improves.

In addition, in the above embodiment, when a metal layer is formed by gold plating or plating on the surface of the portion of the ball seat 2 that covers the groove 6, the inner wall surface of the ink guide hole 5H may be entirely made of a metal surface. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the main part of this invention, and FIG. 2 is a cross-sectional view of the same. In the figure, reference numeral 1 is a cylinder shaft, 2 is a ball seat, 3 is a ball, a is an ink supply chamber, b is a ball chamber, 4 is a tip, 5H is an ink guiding hole, and 6 is a groove.

Claims (1)

[Scope of utility model registration request] A synthetic resin ball seat is tightly inserted and fixed into a metal cylinder shaft to divide it into an ink supply cylinder and a ball chamber, and the tip of the ball chamber is narrowed to such an extent that a part of the ball is exposed from the ball chamber. In a ballpoint pen that holds a ball, a groove is formed on the inner circumferential surface of the cylindrical shaft that the ball seat contacts, and the opening of this groove is covered with the circumferential side of the cylindrical ball seat. An ink guide hole in a ballpoint pen tip, characterized by having a guide hole.