JP4339017B2 - Ballpoint pen cap - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ballpoint pen cap provided with an elastic body that seals the tip of a tip.
[0002]
[Prior art]
Conventional ballpoint pens that have been directly packed with low-viscosity water-based ink or shear-thinning ink inside the ink storage cylinder or shaft cylinder, even when the cap is attached to the shaft cylinder, the internal pressure rises and the tip of the tip If the is facing down, ink leaks from the tip of the tip. For this reason, an elastic body made of rubber or the like is disposed in the inner hole of the cap, and when the cap is mounted, the tip end of the chip is pressed against the elastic body, and the elastic body is compressed and deformed to seal the tip end of the chip. Writing instrument caps that prevent ink leakage are known.
[0003]
Examples of the elastic body that seals the tip end of the tip are disclosed in Japanese Utility Model Publication No. 5-3346 “Clip of writing instrument” and spherical elastic body disclosed in Utility Model Registration No. 2566664 “Applicator”. There are known elastic bodies that have a depression on the opposite side of the surface that contacts the tip end of the chip, have a substantially H-shaped longitudinal section, and have a flat and spherical surface that contacts the tip of the chip. .
[0004]
[Patent Document 1]
"Actual Publication No. 5-3346"
[Patent Document 2]
“Utility Model Registration No. 2566664 Publication”
[0005]
[Problems to be solved by the invention]
However, in the conventional elastic body, the former spherical elastic body presses the tip end of the tip against the elastic body and seals the tip end only by compressive deformation of the elastic body. When stored for a long period of time, the elastic body remains in a deformed state, and it becomes difficult to return to the original spherical shape, and it is difficult to seal the tip of the tip when the cap is next applied.
[0006]
The latter has a recess on the opposite side to the surface that contacts the tip end of the chip, and the vertical cross section has a substantially H shape, and has a recess on the side opposite to the surface that contacts the tip end of the chip. It is easy to return to the original state due to the elastic force coming from, but when the tip end of the tip is pressed against the elastic body, the joint between the surface (horizontal bar) that contacts the tip end of the tip and another surface (vertical bar) If the tension is high and the pressure contact force is high, the joint may crack, and if it is severe, it may be broken.
[0007]
In addition, the elastic body having a flat contact surface has a flat contact portion with the tip of the tip, the tip is a ball, and the ballpoint pen tip is gradually reduced in diameter toward the tip. There was a problem that could not be sealed completely due to insufficient pressure input. Also, if the tip end of the chip is abruptly sealed, there is a problem that air between the elastic body and the tip end of the chip enters from between the ball and the inner wall of the tip end of the chip, so-called air entrapment phenomenon occurs. [0008]
In view of the above problems, the present invention provides a ballpoint pen cap provided with an elastic body that easily returns to its original state and is less likely to cause air entrapment.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, in a ballpoint pen cap provided with an elastic body that seals the tip end portion of a ballpoint pen tip that rotatably holds a ball, the longitudinal section of the elastic body has a tip. the tip portions projecting portion abutting side, the outer diameter of a substantially M-shape comprising a small substantially U-shape gradually toward the front end, abuts a surface on at least the tip end portion is a circular arc shape.
[0010]
The elastic body in the present invention has a substantially M-shape that protrudes to the side that contacts the tip end of the chip, and that has a longitudinal section that includes a substantially U-shape whose outer diameter gradually decreases toward the tip .
[0011]
Elastic bodies are elastic elastically deformable natural rubber, silicone rubber, butyl rubber, fluorine rubber, vinyl chloride resin, butadiene rubber, urethane rubber, polyethylene resin, and other synthetic rubbers that are generally known. Therefore, it may be selected as appropriate according to the material and structure of the tip of the chip, the ink components, and the like.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
The cap 1 of the ballpoint pen of the first embodiment shown in FIG. 1 and FIG. 2 is provided with a protrusion 4 that engages with a protrusion 7 provided on the shaft tube 6 on the inner surface of the opening 2a of the cap body 2. Yes, the tip 2b is formed with a step so that the elastic body 3 is mounted. A clip 5 is formed integrally with the cap body 2.
[0013]
Although not shown in the state in which the elastic body 3 is mounted in the cap main body 2, a ballpoint pen refill in which a ballpoint pen tip 9 holding a ball rotatably is held at the tip of the ink storage cylinder is held by a gripping portion. When the shaft cylinder 6 and the cap 2 are fitted together, first, the longitudinal section projecting to the part abutting against the tip end portion 9a is substantially U-shaped. When the elastic body 3 having an arc-shaped surface 3a that contacts the tip end of the chip contacts the tip end 9a and further fits, the tip end 9a comes into pressure contact with the elastic body 3, and the longitudinal section has an outer diameter. The tip end portion 9a is hermetically sealed by the deformation of the substantially U-shaped elastic body 3 that gradually decreases toward the tip. By making the surface 3a in contact with the tip end portion 9a into an arc shape, the tip end portion 9a is not suddenly covered, so that it is difficult for air to stagnate into the tip due to mounting.
[0014]
When the cap 1 is removed from the shaft tube 6, the restoring force of the elastic body 3 itself and the longitudinal section of the elastic body 3 are substantially U-shaped with the outer diameter gradually decreasing toward the tip. Restores the original shape by force. Furthermore, even if the pressure contact force is increased, there is no portion to which excessive addition is applied, so that the elastic body 3 is unlikely to crack.
[0015]
A ballpoint pen cap 21 according to the second embodiment shown in FIG. 3 has a substantially M-shape including a substantially U-shape with an outer diameter gradually decreasing toward the tip in a part of a longitudinal section of the elastic body 23. In the same manner as in the first embodiment except that the surface 23a that comes into contact with the tip end of the tip is an arc shape, the inner surface of the opening 22a of the cap body 22 is engaged with the protrusion 7 provided on the shaft tube 6. A mating protrusion 24 is provided, and the tip 22b is formed with a step so that the elastic body 23 is attached. By making the longitudinal section of the elastic body 23 substantially M-shaped, the elastic force due to the structure is further improved, so that the restoring force when the cap is removed can be increased.
[0016]
The ball-point pen cap 31 of the third embodiment shown in FIG. 4 includes a substantially U-shaped part of the longitudinal section of the elastic body 33 that gradually decreases in outer diameter toward the tip. In the same manner as in the first embodiment, except that the surface 33a abutting on the tip end of the chip is formed in an arc shape, the shaft cylinder 6 is formed on the inner surface of the opening 32a of the cap body 32. A protrusion 34 that engages with the provided protrusion 7 is provided, and the tip 32b is formed with a step so that the elastic body 33 is attached. In order to make the longitudinal section of the elastic body 33 substantially O-shaped, it may be a sphere or cylinder. However, since the sphere has no directionality, the assemblability can be improved.
[0017]
In this embodiment, for the sake of convenience, the fitting method between the cap and the shaft tube is a fitting between the protruding portion and the protruding portion. However, generally known caps and shaft tubes, such as concave-convex fitting and press-fitting fitting, are used. The fitting method can be used. Further, the contact timing of the tip end portion and the elastic body is not particularly limited as long as the elastic body is compressed and deformed and the tip end portion of the chip can be sealed with the cap and the main body completely attached.
[0018]
【The invention's effect】
Since the present invention has the configuration described above, it has been possible to provide a ballpoint pen cap provided with an elastic body that is easy to return to its original state and is less likely to cause air entrapment.
[Brief description of the drawings]
FIG. 1 is an enlarged longitudinal sectional view of a cap showing a first embodiment.
FIG. 2 is an enlarged longitudinal sectional view with a part omitted, with a cap mounted on a shaft cylinder.
FIG. 3 is an enlarged vertical sectional view of a cap showing a second embodiment.
FIG. 4 is an enlarged longitudinal sectional view of a cap, showing a third embodiment.
[Explanation of symbols]
1, 21, 31 Ballpoint pen cap 2, 22, 32 Cap body 2a, 22a, 32a Cap rear end opening 2b, 22b, 32b Cap tip 3, 23, 33 Elastic body 4, 24, 34 Projection 6 Shaft 6 7 Convex 9 Tip end

Claims (1)

In a ballpoint pen cap provided with an elastic body that seals the tip end portion of the ballpoint pen tip that rotatably holds the ball, the longitudinal section of the elastic body protrudes toward the portion that contacts the tip end portion . A ballpoint pen cap having an approximately M-shape including an approximately U-shape whose outer diameter gradually decreases toward the tip, and at least a surface abutting on the tip end is an arc shape.

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