JPH0221269Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a writing instrument cartridge for a knock-type writing instrument, which is housed in a barrel and has a pen tip that can be moved in and out of the tip of the barrel using an appropriate mechanism.

Notsuku-style writing instruments have excellent operability, but only writing instruments that use extremely viscous ink, such as oil-based ink ballpoint pens, are in practical use, and the handwriting does not penetrate to the back side of the paper or is not very clear. Although many inventions and ideas have been made for writing instruments using water-based ink, which have the advantage of producing fine handwriting and are preferred for general writing, they have not yet been put into practical use. The current situation is that this is not the case. The main reason for this is when the pen tip dries out when the cartridge is not in use (when the cartridge is stored in the barrel) and air flows in through the air hole provided at the front of the writing instrument cartridge, causing the ink inside to dry and causing ink smearing. In order to prevent this, a sealing structure was required within the tip of the shaft cylinder, and this sealing structure was technically extremely advanced, making it impossible to achieve the intended purpose.

Therefore, the applicant came to the conclusion that in order to obtain a practical writing instrument using water-based ink, there was a technical limit to the pursuit of a sealed structure.
As a countermeasure, we previously proposed installing an air hole in the tail plug at the rear of the writing instrument cartridge, but subsequent research revealed that the diameter and length of the air hole are extremely delicate, and that Air hole provided in the section (diameter is approximately 0.5 to 1 mm)
It has been found that relatively preferable results can be obtained when the diameter is smaller, for example, 0.5 mm or less. However, in order to form air holes in the tail plug, cutting using a cutting tool such as a drill or reamer, which is a conventional method for forming holes, is required.
When special processing such as electrical discharge machining, laser processing, or injection molding was used, the following problems occurred.

In other words, in the case of , the limit for machining a minute hole is to a depth of 3 to 5 times the diameter of the cutter, and drilling a hole deeper than that may damage the cutter and cause the workpiece to become unworkable. In the case of resin, the problem is that the heat generated by the cutter melts the holes, causing them to close up or become bent. This is possible if the processing is focused on the purpose, but the problem is that the surface becomes rough due to the heat of processing, resulting in poor accuracy, and it takes a lot of processing time and setup time. On the mold, a core pin is required for forming micropores, but it is technically impossible to maintain such a core pin so that it does not bend due to the internal pressure of the resin. Micropores become bent due to contraction,
The problem is that it gets blocked.

Therefore, we investigated how to accurately form an air hole with a small diameter and appropriate length in the tail plug, and as a result, we completed the present invention. This type of writing instrument has a mechanism that allows the pen tip to protrude and retract from the tip of the barrel.The ink storage body that stores water-based ink is stored inside, and the rear part is composed of an external material and an internal material, with the internal material being the external material. The gist of the present invention is to provide a writing instrument cartridge for a lock-type writing instrument, in which a tail plug is arranged so that a linear non-contacting part formed between the two becomes an air hole when the two are fixed.

The present invention will be described in detail below based on embodiments shown in the accompanying drawings.

Reference numeral 1 denotes a writing instrument cartridge made of metal or the like, in which an ink storage body 2 for storing water-based ink is housed, and a tail plug 3 made of resin or the like is disposed at the rear of the writing instrument cartridge 1. There is. This tail plug 3 is composed of an outer member 4 and an inner member 5. The outer member 4, which has a through hole 4a formed therein, is fixed at its front part 4b to the rear part of the writing instrument cartridge 1 by an appropriate fastening means such as press fitting. The inner member 5 has a rod-shaped portion 5b having approximately the same outer diameter as the through-hole 4a of the outer member 4, and further has a linear notch 5a formed therein, and is press-fitted and fixed into the through-hole 4a of the outer member 4. During this press-fitting and fixing, a longitudinal linear non-contact portion 6 formed between the linear notch 5a of the rod-shaped portion 5b and the through hole 4a serves as an air hole. 4c is external material 4
A ventilation slit formed in the front part of the
The reason why the slit 4c and the space 7 behind the slit 4c are stepped is that when an impact is applied to the cartridge, the ink impregnated in the ink storage body 2 enters the linear non-contact part 6 (air hole). This is to prevent it from flowing into the

As described above, the present invention consists of a tail plug made of an external material and an internal material, and when the internal material is press-fitted into the external material, a longitudinal straight non-contact line is formed between the internal material and the external material. Since the part is made into an air hole, there are no problems like those mentioned above or in the processing method, and if the dimensions of the internal material and external material are controlled, it can be made with a small diameter (corresponding cross-sectional area) and sufficient length. It is possible to easily obtain an air hole having a diameter of 100 mm, and it is possible to prevent as much as possible the problem of ink smearing caused by drying of the ink in the writing instrument cartridge.

In the example, a notch was provided in the rod-shaped part to form a linear non-contact part, but a rod-shaped part with a circular cross section was press-fitted into a through hole with an elliptical cross section, and the non-contact part was formed. may be formed.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a main part, and FIG. 2 is a cross-sectional view taken along the line A--A in FIG. 1. 1... Writing instrument cartridge, 2... Ink absorber, 3... Tail plug, 4... External material, 5... Internal material,
6... Straight non-contact part.

Claims (1)

[Scope of utility model registration request] A lock-type writing instrument that is stored in a barrel and has a retractable mechanism that allows the pen tip to protrude and retract from the tip of the barrel.The ink storage body that stores water-based ink is stored inside, and the rear part is made up of an external material and an internal material. is,
A writing instrument cartridge for a lock-type writing instrument in which a tail plug is arranged in which a linear non-contact part formed between the inner member and the outer member is used as an air hole when the inner member is fixed to the outer member.