JP3859992B2 - Writing instrument cap mating structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cap fitting structure for a writing instrument molded from a synthetic resin.
[0002]
[Prior art]
The structure of fitting a cap made of synthetic resin to the writing instrument body is formed with an annular outward locking projection on the outer peripheral surface of the fitting part of the writing instrument body, and also inward on the inner peripheral surface of the fitting cylinder part of the cap In many cases, the cap is fitted to the writing instrument body by forming the locking protrusion and the inward locking protrusion overcoming the outward locking protrusion. Here, the feed link is important when the inward locking projection gets over the outward locking projection, and the inward locking projection needs to get over the outward locking projection with an appropriate pressing force. Is required to remain unchanged even after long-term use.
[0003]
[Problems to be solved by the invention]
In such a writing instrument cap fitting structure, when the cap's inward locking projection gets over the outward locking projection of the writing instrument body and the cap fitting is completed, the inward locking projection is the outer periphery of the fitting portion of the writing instrument body. Designed to abut the surface. In the case of a writing instrument such as a sign pen that needs to prevent ink evaporation due to the tightness of the fitting part of the cap, the inward locking protrusion is brought into contact with the outer peripheral surface of the fitting part of the writing instrument body. In order to improve the airtightness of the cap and to reduce the “rattle” of the cap when mated, even in the case of a writing instrument that does not require much prevention of ink evaporation at the mating portion of the cap. The inward engagement protrusion is brought into contact with the outer peripheral surface of the fitting portion of the writing instrument body.
[0004]
However, if the inward engagement protrusion formed on the fitting tube portion of the synthetic resin cap is brought into contact with the outer peripheral surface of the fitting portion of the writing instrument body, the fitting tube portion of the cap is always stressed. The inner diameter of the fitting cylinder portion gradually increases due to the stress relaxation phenomenon of the synthetic resin. For this reason, the pressing force required at the time of cap fitting gradually decreases, and there is a problem that the feeling of cap fitting changes when used for a long time.
[0005]
Accordingly, an object of the present invention is to provide a cap fitting structure for a writing instrument made of a synthetic resin, in which the feeling at the time of cap fitting does not change even after long-term use.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a seal body made of a soft elastic body at the bottom of the cap body, and the pen body is covered with the seal body when the cap is mounted on the writing instrument body. An annular outward locking projection is formed on the outer peripheral surface of the fitting portion of the writing instrument body, and an inward locking projection is formed on the inner peripheral surface of the fitting tube portion of the synthetic resin cap. In the cap fitting structure of a writing instrument in which the direction locking projections overcome the outward locking projections and the cap is fitted, the fitting portion cylinder is integrally formed in a double cylinder state on the middle part of the cap body , The inward locking protrusion is prevented from coming into contact with the fitting portion of the writing instrument main body when the direction locking protrusion gets over the outward locking protrusion and the cap fitting is completed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows an example in which the present invention is applied to a ballpoint pen. In FIG. 1, a tip end 14 is screwed to the tip end of a shaft tube 10, and the shaft tube 10 and the tip port 14 constitute a writing instrument main body. A grip 13 made of a soft elastic body is fitted into a portion where the fingertip comes into contact with the shaft tube 10 during writing. A ballpoint pen feel (not shown) is built in the shaft cylinder 10, and a ballpoint pen body 15 at the tip of the tip of the ballpoint pen projects from the tip opening of the tip 14.
[0008]
A fitting cylinder portion 21 is integrally formed in a double cylinder state on the inner middle of a cap body 20 formed in a substantially cylindrical shape with a synthetic resin, for example, polycarbonate. A crown 25 in which the clip 26 is integrated is fitted into the tail end opening of the cap body 20, and the cap body 20 and the crown 25 constitute a cap. A spherical seal body 27 made of a soft elastic body is disposed at the bottom of the cap body 20, and when the cap is fitted to the writing instrument body, the ballpoint pen body 15 is covered with the seal body 27 to evaporate the ink. It comes to prevent.
[0009]
The distal end portion of the shaft tube 10 is a fitting portion 11 having a slightly small diameter. As shown in FIG. 2, the outer peripheral surface of the fitting portion 11 has an annular shape and has an arcuate surface shape. A stop projection 12 is formed. Therefore, the fitting part 11 is divided into the fitting part 11 on the front end side and the fitting part 11 on the tail end side by the outward locking projection 12. On the other hand, on the inner peripheral surface of the fitting cylinder portion 21 of the cap main body 20, an inward locking protrusion 22 is formed which has an annular shape and has a gentle arc shape on the surface.
[0010]
Then, when the writing instrument body is inserted into the cap body 20, the inward locking protrusion 22 gets over the outward locking protrusion 12, and the inward locking protrusion 22 and the outward locking protrusion 12 are engaged and fitted. The tip 21a of the tube portion 21 abuts on the step portion 10a of the shaft tube 10 to complete the cap fitting. At this time, the inward locking protrusion 22 is not in contact with the fitting portion 11 of the shaft tube 10. Therefore, the stress which pushes the fitting cylinder part 21 outward is small, and even if it is used for a long time, the stress relaxation phenomenon of the synthetic resin constituting the fitting cylinder part 21 hardly occurs, and the inner diameter of the fitting cylinder part 21 is enlarged. There is little to do. For this reason, even if it is used for a long time, the cap can be fitted with a constant pressing force, and the feeling during cap fitting does not change.
Thus, in the present invention, since the inward engagement protrusion 22 is not in contact with the fitting portion 11 of the shaft tube 10, the airtightness at the fitting portion of the cap is somewhat inferior, but like a tip-sealed ballpoint pen. Moreover, it is suitable for a writing instrument that does not require much prevention of ink evaporation at the fitting portion of the cap.
[0011]
【The invention's effect】
As described above, according to the present invention, the seal body made of the soft elastic body is arranged at the bottom of the cap body, and the pen body is covered with the seal body when the cap is mounted on the writing instrument body, thereby preventing ink evaporation. An annular outward locking protrusion is formed on the outer peripheral surface of the fitting portion of the writing instrument body, and an inward locking protrusion is formed on the inner peripheral surface of the fitting tube portion of the synthetic resin cap. In a cap fitting structure of a writing instrument in which a projection is passed over the outward locking projection and the cap is fitted, the fitting portion cylinder is integrally formed in a double cylinder state on the middle part of the cap body , and inwardly locked. When the cap has been fitted over the outward locking projection, the inward locking projection does not contact the fitting part of the writing instrument body. Cap fitting structure for writing instruments made of synthetic resin that does not change It can be.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment of the present invention.
FIG. 2 is an enlarged view of a portion shown in FIG. 1A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Shaft cylinder 11 Fitting part 12 Outward latching protrusion 13 Grip 14 Base 15 Ball-point pen body 20 Cap main body 21 Engagement cylinder part 22 Inward latching protrusion 25 Head crown 26 Clip 27 Seal body

Claims (1)

A seal body made of a soft elastic body is arranged at the bottom of the cap body, and when the cap is mounted on the writing instrument body, the pen body is covered with the sealing body to prevent ink evaporation , and the outer periphery of the fitting part of the writing instrument body An annular outward locking projection is formed on the surface, an inward locking projection is formed on the inner peripheral surface of the fitting tube portion of the synthetic resin cap, and the inward locking projection is connected to the outward locking projection. In the cap fitting structure of a writing instrument that gets over the cap,
The fitting part cylinder is integrally formed in a double cylinder state on the middle part of the cap body, and when the inward locking protrusion has overcome the outward locking protrusion, the inward movement is completed. A cap fitting structure for a writing instrument, wherein the locking projection does not contact the fitting part of the writing instrument body.

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