JP4879669B2 - Ballpoint pen tip - Google Patents

Description

  The present invention relates to a ballpoint pen tip mounted on the foremost end of a ballpoint pen refill, and more particularly to a ballpoint tip having a chip body that holds a transfer ball formed of a synthetic resin material.

Conventionally, in a metal ballpoint pen tip, as described in Patent Document 1, a ball transfer (20) is inserted into a ball house (13) and pressed in the ball stage (13) at the manufacturing stage. An indentation is formed on the bottom surface (13a) of this, and this indentation is used as a ball seat (13a1) for receiving the rotating transfer ball (20).
By the way, according to such a metal ballpoint pen tip, the corner of the tip end portion of the tip body (10) is rubbed against the paper surface, the writing feeling is lowered, or scraped paper dust is transferred to the transfer ball (20). There is a risk of problems such as being caught.
Therefore, it is conceivable to form the chip body from a synthetic resin material so as to prevent the reduction in writing feeling and the generation of paper dust as described above.

However, when a chip body similar to that of Patent Document 1 is made of a synthetic resin material, it is necessary to previously form the ball seat (13a1), which is an impression of the transfer ball, at the molding stage. .
For this reason, the curvature of the outer peripheral surface of the transfer ball may not match the curvature of the ball seat due to variations in molding accuracy. In such a case, for example, when the curvature of the ball receiving seat is larger than the curvature of the outer peripheral surface of the transfer ball, the transfer ball may bite into the ball receiving seat and the transfer ball may be prevented from rotating. There is.
JP 2003-48393 A

  The present invention has been made in view of the above-described conventional circumstances, and a problem to be solved by the present invention is to provide a tip for a ballpoint pen in which a transfer ball rotates smoothly and has a good writing feeling.

In order to solve the above-described problems, a first invention is provided in a front end side of a chip body made of a synthetic resin material, an intersecting surface intersecting the axis of the chip body, and an ink positioned behind the intersecting surface. In a ballpoint pen tip provided with a guide hole, rotatably holding a transfer ball in front of the intersecting surface, and supplying ink to the transfer ball through the ink guide hole, the intersecting surface is than the outer peripheral surface of the transfer ball is formed slightly smaller concave surface curvature, that the concave curved surface and the ink induction hole corners only crossing was a ball seat for receiving the outer peripheral surface of the transfer ball Features.

The material of the transfer ball is not limited and can be, for example, stainless steel, ceramic, synthetic resin material, or the like.
Further, the intersecting surface is not good if the plane intersecting the axial center of the chip body.

In the second invention, the tip body has an inward tip edge that is reduced in diameter so as to be smaller than the outer diameter of the transfer ball on the inner surface on the foremost end side, and along the ink guide hole. The ink guide groove is continuous to the rear, and the ink guide groove is connected to the inclined bottom surface portion whose depth dimension is gradually shallower toward the rear and the rear end of the inclined bottom surface portion, and the depth dimension is rearward. The parallel bottom surface portion is arranged on the centripetal direction side with respect to the inner peripheral surface of the inward leading edge .

Here, the “depth of the ink guide groove” means the depth of the bottom of the ink guide groove in the radial direction of the chip body .

Further, in the third invention, a large-diameter portion having a cylindrical shape having an inner diameter slightly larger than that of the transfer ball and connected to the intersecting surface is provided in front of the intersecting surface inside the front end side of the chip body. And having a bottomed ink reservoir hole opened forward so as to be continuous with the inner peripheral surface of the large-diameter portion .

Since the present invention is configured as described above, the following effects can be obtained.
According to the first aspect of the invention, only the corner portion where the intersecting surface and the ink guide hole intersect acts as a ball receiving seat, and the ball receiving seat slides in a point-contact manner with respect to the outer peripheral surface of the transfer ball. Touch.
Therefore, it is possible to prevent the transfer ball from biting into the ball seat, and since the contact area between the transfer ball and the ball seat is relatively small, the ball rotates smoothly and the writing feeling is good. .
In addition, even if the tip of the chip body rubs against the paper surface, it is possible to prevent the paper surface from being scraped, and in addition, the chip body made of a synthetic resin material is elastically deformed slightly by writing pressure. Therefore, a soft writing feeling can be obtained.
Therefore, it is possible to provide a ballpoint pen tip that has a smooth rotation of the transfer ball and a good writing feeling.

  Furthermore, according to the second invention, when the chip body made of a synthetic resin material is molded, the molding die for molding the ink guide groove is in sliding contact with the inward leading edge, and the inward leading edge is damaged. Can be prevented, and it is highly productive.

Furthermore, according to the third invention, even when the writing tip is kept upward for exhibition or the like, the ink can be stored in the ink storage hole, and thus, from upward to downward. When writing is started, it is possible to prevent the occurrence of writing drowning.
That is, according to the configuration without the ink reservoir hole, when the writing tip is maintained upward for exhibition or the like, the ink moves backward by its own weight (referred to as a drain back phenomenon). Due to this, there is a case where writing drowning occurs when writing is started. However, according to the present invention, even if the drain back phenomenon occurs, the ink stored in the ink storage hole is ejected until the ink returns to the writing tip, so that the writing stagnation as described above is performed. Can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A tip A for a ballpoint pen according to the present invention includes a tip body 10 that can be connected to a front end of an ink storage tube (not shown), and a transfer ball 20 that is rotatably held in the tip body 10. Is supplied to the transfer ball 20 and is transferred from the outer peripheral surface of the transfer ball 20 to a writing object such as a paper surface.

  The chip body 10 is integrally formed from a relatively flexible synthetic resin material such as POM (polyacetal), for example, and the tip side outer peripheral surface is formed in a tapered shape, and the transfer ball 20 is held inside the chip body 10. And the ink guide hole 12 and the ink guide groove 13 for guiding ink into the ball house 11, the ink passage 14 for supplying ink from the rear side of the ink guide hole 12 and the ink guide groove 13, and the like.

The ball house 11 has an inward leading edge 11a having a diameter reduced to be smaller than the outer diameter of the transfer ball 20 at the foremost end, and the inward leading edge 11a allows the transfer ball 20 to be chipped. The body 10 is prevented from being pulled out.
The ball house 11 has, on the rear side of the inward leading edge 11a, a large-diameter portion 11b formed with an inner diameter slightly larger than the outer diameter of the transfer ball 20, and further, than the large-diameter portion 11b. On the rear side, there is an intersecting surface 11 c that intersects the axis of the chip body 10.

The intersecting surface 11c is a curved surface formed to have a curvature slightly smaller than the curvature of the outer peripheral surface of the transfer ball 20, and a plurality of the intersecting surfaces 11c are arranged at predetermined intervals in the circumferential direction of the chip body 10 as shown in FIGS. Is done.
A space formed at the center of the plurality of intersecting surfaces 11c is an ink guide hole 12 described later, and a space between the intersecting surfaces 11c and 11c adjacent in the circumferential direction is an ink guide groove 13 described later.

In addition, an ink storage hole 15 is formed on the front end side of each intersecting surface 11c.
The ink storage hole 15 is a bottomed hole that is open toward the front, and is disposed so as to be continuous from the inner peripheral surface of the large-diameter portion 11b of the ball house 11, and the chip body 10 is directed upward. In this case, the ink is temporarily stored.

  The ink guide hole 12 is a through hole that continues from the ball house 11 to the ink passage 14 along the axis of the chip body 10, and has an inner peripheral surface communicating with the plurality of ink guide grooves 13.

Further, each ink guide groove 13 communicates between the ball house 11 and the ink passage 14 and also communicates with the ink guide hole 12 so as to pass between the intersecting surfaces 11c adjacent in the circumferential direction. Is formed.
The ink guide groove 13 is formed such that its depth (more specifically, the dimension from the inner peripheral surface of the ink guide hole 12 toward the centrifugal direction) becomes shallower toward the rear.
In more detail about the illustrated example, the ink guide grooves 13 on its front end side, the depth dimension x1 has gradually shallow Kunar inclined bottom surface portion 13a toward the rear than the inclined bottom surface portion 13a Also on the rear side, there is a parallel bottom surface portion 13b in which the depth dimension x2 is substantially constant parallel to the axis of the chip body 10.
According to a preferred example of the present embodiment, the parallel bottom surface portion 13b is located closer to the centripetal direction side than the inner peripheral surface of the inward leading edge 11a.

  According to the inclined bottom surface portion 13a and the parallel bottom surface portion 13b configured as described above, when the molding die in the ink guide groove 13 is pulled forward (to the left in FIG. 1) in the ink guide groove 13 forming step. The molding die is pulled out with little contact with the inward leading edge 11a. Therefore, it is possible to prevent the inward leading edge 11a from being damaged during die cutting in the molding process.

The ink passage 14 is a hole that continues to the rear end portion of the chip body 10 and further continues to an ink storage tube (not shown) to be connected.
An ink guide core 16 is inserted into the ink passage 14. The ink guide core 16 is formed of, for example, a porous material so as to guide the ink in the ink storage tube forward by capillary force.

The transfer ball 20 is formed in a substantially spherical shape from, for example, a metal material, ceramic, hard synthetic resin material, or the like.
The transfer ball 20 is formed to have a larger outer diameter than the inward leading edge 11 a of the chip body 10.
Therefore, when the transfer ball 20 is inserted into the ball house 11 of the chip body 10, the transfer ball 20 is pressed against the inner peripheral surface of the inward tip edge 11 a, so that the inward tip of the chip body 10. The edge 11a side is elastically slightly expanded in diameter, and the transfer ball 20 enters the ball house 11 through the expanded diameter portion. After the entry, the inward leading edge 11a is elastically restored. The diameter is reduced.

In the chip body 10 in which the transfer ball 20 is embedded as described above, only the corner portion where the intersecting surface 11 c and the ink guide hole 12 intersect is used as a ball receiving seat p for receiving the outer peripheral surface of the transfer ball 20. Yes.
That is, the front-facing surface of the intersecting surface 11 c is not in contact with the outer peripheral surface of the transfer ball 20, and only the ball receiving seat p that is the corner contacts the outer peripheral surface of the transfer ball 20.
As shown in FIGS. 2 and 3, each ball receiving seat p is an arc-shaped line constituting the front end edge of the ink guide hole 12 in the circumferential direction of the chip body 10.

Thus, according to the ballpoint pen tip A configured as described above, when a pressing force from the front to the back is applied to the transfer ball 20 by the writing pressure, the transfer ball 20 intersects the cross surface 11c and the ink guide hole 12. It is received only by the ball receiving seat p which is a corner portion to be performed. As shown in FIG. 1, the contact at that time is a point contact on the longitudinal section.
That is, the intersecting surface 11c having a smaller curvature than the outer peripheral surface of the transfer ball 20 does not come into surface contact with the outer peripheral surface of the transfer ball 20 and does not bite into the outer peripheral surface. Only the seat p contacts the outer peripheral surface of the transfer ball 20.
Therefore, the contact area between the transfer ball 20 and the ball seat p is relatively small, and the transfer ball 20 rotates smoothly, so that the writing feeling is good.
In addition, even when the most advanced corner q (see FIG. 1) of the chip body 10 is rubbed against the paper surface, the chip surface 10 made of a synthetic resin material can be prevented from being scraped off. Since it is elastically deformed slightly by pressure, a soft writing feeling can be obtained.
Further, even when the ball receiving seat p, which is a corner portion, is worn due to long-term use or the like, the portion close to the ball receiving seat p of the intersecting surface 11c comes into contact with the transfer ball 20, so that the stable transfer ball Twenty rotations are obtained.

It is a principal part longitudinal cross-sectional view of the tip for ball-point pens concerning this invention. It is a principal part longitudinal cross-sectional view which shows the front-end side of the chip | tip main body of the chip | tip for the same ball-point pen. It is the (III)-(III) sectional view taken on the line in FIG.

Explanation of symbols

10: Chip body 11a: Inward leading edge 11c: Crossing surface 12: Ink guide hole 13: Ink guide groove 15: Ink storage hole 20: Transfer ball p: Ball seat

Claims (3)

Provided inside the front end side of the chip body made of a synthetic resin material is an intersecting surface intersecting the axis of the chip body and an ink guide hole located behind the intersecting surface, on the front side of the intersecting surface In a ballpoint pen tip that holds a transfer ball in a freely rotatable manner and supplies ink to the transfer ball through an ink guide hole.
Said intersecting surfaces is formed slightly smaller concave surface curvature of the outer circumferential surface of the transfer balls, only corners this concave surface and the ink induction hole intersect, the ball receiver for receiving the outer peripheral surface of the transfer ball A tip for a ballpoint pen characterized by a seat. The chip body has an inward leading edge that is reduced in diameter so as to be smaller than the outer diameter of the transfer ball on the inner surface on the foremost end side, and an ink guide groove that continues to the rear along the ink guide hole. Prepared,
The ink guide groove includes an inclined bottom surface portion whose depth dimension gradually decreases toward the rear, and a parallel bottom surface portion connected to the rear end of the inclined bottom surface portion and having a substantially constant depth dimension toward the rear. 2. The ballpoint pen tip according to claim 1 , wherein the parallel bottom surface portion is disposed closer to a centripetal direction side than an inner peripheral surface of the inward leading edge . In the front side of the front end side of the chip body, on the front side of the crossing surface, it has a cylindrical shape with an inner diameter slightly larger than the transfer ball and connected to the crossing surface,
In the intersecting plane, the claim 1 or 2, wherein the ballpoint pen tip, characterized in that a bottomed ink reservoir hole which is open toward the front so as to be continuous to the inner peripheral surface of the large diameter portion .

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