JP2009119628A - Writing utensil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a writing utensil that, with a simple structure, facilitates absorption of errors in a refill length in manufacturing and that eliminates generation of a gap on the outer circumference of a barrel. <P>SOLUTION: The writing utensil 1 is provided with an extremely simple structure in which a female screw part 15 is formed on the inner circumference of the barrel 2 while a male screw part 14 is formed on the outer circumference of a tail plug 4. For example, with the female screw part 15 formed long, a refill 3 can be surely held with a desired tightening force using the tail plug 4 even in the occurrence of large variance in the length of the refill 3. In particular, in exchanging the refill 3 when an ink runs out, this writing utensil is desirable because of its large allowable range against variance in the length of the refill 3. Further, since the tail plug 4 is mounted in the barrel 2, there is no gap produced on the outer circumference of the barrel 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a writing instrument such as a ballpoint pen, a marking pen, a sign pen, a fountain pen, and a correction pen.

  Conventionally, there is JP 2002-67572 A as a technique in such a field. The writing instrument described in this publication is a ballpoint pen, a pen tip holder that is press-fitted and held at the front end of the pen tip, an ink storage tube (refill) in which the pen tip holder is press-fitted and fixed to the front end opening, and an ink storage tube Is provided with a shaft tube accommodated therein and a tail plug fitted into the rear end opening of the shaft tube. The tail plug is obtained by injection molding of a synthetic resin, and has a bottomed cylindrical inner cylinder portion having a front end opened and a rear end closed, and an inner cylinder portion inside, the front end being opened and the rear end And a bottomed cylindrical outer cylinder part closed with a concentric and continuous connection. On the inner surface of the outer tube portion, a female screw portion that is screwed with the male screw portion on the outer surface of the rear end portion of the shaft tube 2 is formed. When the tail plug is screwed to the rear end portion of the shaft tube, the step portion and the front end of the outer tube portion are set to have a gap in the axial direction. Further, in a state where the tail plug is screwed to the rear end portion of the shaft tube, the annular bottom wall of the outer tube portion is in axial contact with the rear end of the shaft tube in an annular shape. As a result, even if the ink and the follower overflow from the inside of the inner cylinder part, the ink and the follower pass between the inner surface of the outer cylinder part of the tail plug and the outer surface of the rear end part of the shaft cylinder. A situation in which the follower leaks can be avoided. Further, in order to bring the front end of the inner tube portion of the tail plug into contact with the rear end of the ink containing tube with the tail plug screwed to the rear end portion of the shaft tube, the outer shape of the front end of the inner tube portion of the tail plug is The outer diameter of the ink storage tube is substantially the same as the outer shape.

JP 2002-67572 A Japanese Utility Model Publication No. 63-148476

In the conventional writing instrument described above, the stepped portion and the front end of the outer tube portion are set to have an axial gap when the tail plug is screwed to the rear end portion of the shaft tube. This is because variation occurs in the length of the ink storage tube (refill) at the time of manufacture, and this variation can be absorbed by the gap. However, if there is such a clearance on the outer peripheral surface of the shaft tube, the size of the ring-shaped clearance will vary, and the appearance will be poor, and dust will easily accumulate in this clearance. If it is designed to eliminate such a gap in order to avoid such a situation, it is necessary to increase the dimensional accuracy of the tail plug and the ink storage tube (refill), resulting in an increase in cost.
Furthermore, in order to prevent the ink and follower from overflowing from the inside of the inner cylinder, the annular bottom wall of the outer cylinder of the tail plug must be in contact with the rear end of the shaft cylinder. If the length of the storage tube (refill) is short, there may be a situation where the inner tube of the tail plug does not have enough force to press the rear end of the ink storage tube, which may cause the ink storage tube to rattle in the shaft tube. is there.
Further, since the tail plug is composed of an outer tube portion and an inner tube portion, the structure is complicated.
In order to solve the above-described problems, for example, as disclosed in Japanese Utility Model Publication No. 63-148476, a spring is disposed between the rear end of the ink storage tube (refill) and the tail plug. However, this has a problem that the number of parts increases and the structure of the writing instrument becomes complicated and the assembly becomes complicated.

  An object of the present invention is to provide a writing instrument that has a simple configuration, can easily absorb errors in the length dimension of a refill during manufacture, and does not generate a gap on the outer peripheral surface of a shaft cylinder.

  The writing instrument according to the present invention is a writing instrument provided with a tail plug for fixing a refill in a shaft cylinder, and the female thread portion provided on the inner peripheral surface of the rear end side of the shaft cylinder on the outer peripheral surface of the tail plug A male screw portion is formed to be screwed with the screw.

  At the time of manufacturing, the refill is a component that is difficult to increase the dimensional accuracy in consideration of the manufacturing cost, and the length of the refill varies greatly, and there are various ways to absorb this variation. Has been made. And the writing instrument which concerns on this invention has the very simple structure which formed the internal thread part in the inner peripheral surface of the axial cylinder, and formed the external thread part in the outer peripheral surface of a tail plug. For example, if the female thread portion is formed long, even if the length of the refill varies greatly, the refill can be reliably pressed with a desired tightening force by the tail plug. In particular, when the refill is exchanged due to running out of ink, the writing instrument according to the present invention is preferable because of a large allowable range with respect to variations in the length of the refill. Further, since the tail plug is loaded in the shaft tube, no gap is generated on the outer peripheral surface of the shaft tube. Then, after the refill is pressed with a desired tightening force by the tail plug, the screwed portion is hardly loosened by the repulsive force of the refill. Thus, the writing instrument according to the present invention can exhibit extremely high effects with a very simple configuration.

Further, the outer peripheral surface of the tail plug is provided with a convex portion that is located between the rear end of the tail plug and the male screw portion and protrudes from the outer peripheral surface, and the top of the convex portion is formed on the inner peripheral surface of the shaft tube. Preferably, it is pressed.
When the tail plug is screwed onto the shaft tube, the top of the convex portion of the tail plug is pressure-bonded to the inner peripheral surface of the shaft tube, so that loosening of the tail plug can be reliably prevented.

In addition, the outer surface of the tail plug is provided with a plurality of ribs located on the rear end side of the tail plug and projecting from the outer surface. The ribs extend in the direction of the central axis of the tail plug, and the tail plug It is preferable that they are arranged at equal intervals on the outer peripheral surface.
With such a configuration, even when the refill is exchanged, finger catching is good, and even a tightly tightened tail plug can be easily turned. Furthermore, even during assembly manufacturing, fingers and jigs can be reliably caught on the tail plug, and the tail plug can be easily rotated with a desired force, so that the efficiency of the assembly work can be improved.

  According to the present invention, with a simple configuration, it is easy to absorb an error in the length of the refill at the time of manufacture, and no gap is generated on the outer peripheral surface of the shaft tube that causes dust to adhere to the shaft tube.

  Hereinafter, preferred embodiments of a writing instrument according to the present invention will be described in detail with reference to the drawings. In the following description, the pen tip side is referred to as “front side”.

  As shown in FIG. 1, a cap-type ballpoint pen 1 as an example of a writing instrument includes a cylindrical shaft cylinder 2 made of a transparent resin, a refill 3 loaded in the shaft cylinder 2, and a rear end of the shaft cylinder 2. And a cap 5 functioning as a lid on the front end side of the shaft tube 2, and a rubber anti-slip grip 6 fixed to the front side of the outer periphery of the shaft tube 2. Has been.

  Furthermore, the cap 5 has a cylindrical cap body 10 made of resin (for example, PET), and a clip 9 that can be opened and closed is attached to the cap body 10 via a U-shaped leaf spring 11. . An opening 10b is provided on the head end 10a side of the cap body 10, and a cap piece 12 is fitted in the opening 10b.

  As shown in FIGS. 2 to 4, the tail plug 4 for fixing the refill 3 accommodated in the shaft cylinder 2 is formed into a cylindrical body by resin (for example, polypropylene), and the diameter of the tail plug 4 is about 6 mm. On the outer peripheral surface on the rear end side of the tail plug 4, male screw portions 14 having a pitch of about 2 mm are formed. On the other hand, a female screw portion 15 into which the male screw portion 14 of the tail plug 4 is screwed is formed on the inner wall surface on the rear end side of the shaft tube 2.

  Further, as shown in FIG. 5, the refill 3 is made of a resin (for example, polypropylene) tube 17 filled with a pigment-containing gel ink and a transparent resin made of a needle-type ballpoint pen tip 18 fixed to the tip. The joint 19 includes a joint plug 20 that connects the distal end side of the tube 17 and the rear end side of the joint 19, and a ball valve 21 that opens and closes the rear end opening of the joint 19 to prevent ink backflow. The refill 3 is inserted from the rear end opening of the hollow portion of the shaft tube 2, and the flange portion 3 a provided on the front side of the refill 3 abuts on a step portion 2 a formed on the inner peripheral surface of the shaft tube 2. By tightening while turning the tail plug 4, the flange portion 3 a of the refill 3 is strongly pressed against the step portion 2 a of the shaft tube 2 while pushing the rear end of the tube 17 of the refill 3 with the tip of the tail plug 4. Is firmly fixed to the barrel 2.

The outer diameter of the distal end of the tail plug 4 is substantially equal to the outer diameter of the rear end of the tube 17, and two semicircular cutout portions 22 are provided at the distal end of the refill 3. Each notch portion 22 functions as ♦ vent ← air circulation port ♦ when the tip of the refill 3 is in close contact with the rear end of the tube 17.

  At the time of manufacture, the refill 3 is a component that is difficult to increase the dimensional accuracy in consideration of the manufacturing cost, and the length dimension of the refill 3 has a very large variation, that is, an error, and how to absorb this variation. Various ideas have been made. The ballpoint pen 1 according to the present invention has a very simple configuration in which the female screw portion 15 is formed on the inner peripheral surface of the shaft tube 2 and the male screw portion 14 is formed on the outer peripheral surface of the tail plug 4. For example, if the female screw portion 15 is formed long, even if the length of the refill 3 varies greatly, the refill 3 can be reliably pressed by the tail plug 4 with a desired tightening force. In particular, the ball-point pen 1 according to the present invention is preferable because the tolerance range of the length of the refill 3 is large when the refill 3 is replaced due to running out of ink. Further, since the tail plug 4 is loaded in the shaft cylinder 2, no gap is generated on the outer peripheral surface of the shaft cylinder 2.

  After the refill 3 is pressed with a desired tightening force by the tail plug 4, the threaded portion is hardly loosened due to the repulsive force of the elastic refill 3, and at the same time, the male screw portion 14 is crimped to the female screw portion 15. Therefore, even if the ink and the follower overflow from the rear end opening of the tube 17 of the refill 3, the situation where the ink and the follower leak from between the tail plug 4 and the shaft tube 2 Avoided. Thus, the ball-point pen 1 according to the present invention can exhibit extremely high effects with a very simple configuration.

  Further, as shown in FIGS. 2 to 4, the outer peripheral surface of the tail plug 4 is provided with six ribs 23 that are located on the rear end side of the tail plug 4 and project from the outer peripheral surface. The tail plug 4 extends in the direction of the central axis L and is arranged on the outer peripheral surface of the tail plug 4 at equal intervals. When the rib 23 having such a shape is employed, even when the refill 3 is replaced, the finger can be easily caught, and the tail plug 4 that is strongly tightened can be easily turned. Furthermore, even during assembly manufacturing, the finger or jig can be reliably caught on the tail plug 4, and the tail plug 4 can be easily rotated with a desired force, so that the efficiency of the assembly work can be improved.

  Furthermore, the outer peripheral surface of the tail plug 4 is provided with a convex portion 25 having a mountain-shaped cross section that is located between the rib 23 and the male screw portion 14 and protrudes from the outer peripheral surface. Two convex portions 25 are arranged on the outer peripheral surface of the tail plug 4 with a phase angle of 180 degrees. The top portion 25 a of the convex portion 25 is pressed against a circumferentially shaped tail plug introduction surface 26 formed between the rear end 2 b of the shaft tube 2 and the female screw portion 15 on the inner peripheral surface of the shaft tube 2. At this time, the top portion 25a of the convex portion 25 is pressed against the tail plug introduction surface 26 while being crushed. As described above, when the tail plug 4 is screwed to the shaft tube 2, the top portion 25 a of the convex portion 25 of the tail plug 4 is pressure-bonded to the tail plug introduction surface 26 of the shaft tube 2. It can be surely prevented.

  Then, by making the screw length of the female screw portion 15 longer than the screw length of the male screw portion 14, the screwing amount of the tail plug 4 can be increased, thereby allowing an allowable range for variations in the length of the refill 3 Can be increased.

  A ring-shaped bulging portion 27 is provided at the rear end of the shaft cylinder 2. When the so-called back insertion of the cap 5 is performed, the bulging portion 27 is pressure-bonded to the inner peripheral surface of the cap 5, so that it is difficult for the cap 5 to be detached from the shaft tube 2 when the ballpoint pen 1 is used.

  It goes without saying that the present invention is not limited to the embodiment described above. For example, the convex portion 25 may be dot-like or linear in the outer peripheral direction of the tail plug 4. The writing instrument according to the present invention is not limited to a ballpoint pen, but includes a marking pen, a sign pen, a fountain pen, a correction pen, and the like.

It is sectional drawing which shows one Embodiment of the writing instrument which concerns on this invention. It is a principal part expanded sectional view of the writing instrument shown by FIG. It is a perspective view which shows the state which removed the tail plug from the axial cylinder. It is a perspective view which shows the state which screwed the tail plug in the axial cylinder. It is a principal part expanded sectional view of the writing instrument shown by FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ball-point pen (writing instrument), 2 ... Shaft cylinder, 3 ... Refill, 4 ... Tail plug, 14 ... Male screw part, 15 ... Female screw part, 23 ... Rib, 25 ... Convex part, 25a ... Top part of convex part, L ... the central axis of the tail plug.

Claims (3)

In a writing instrument with a tail plug to fix the refill in the shaft tube,
The writing instrument according to claim 1, wherein a male screw portion is formed on the outer peripheral surface of the tail plug so as to be screwed into a female screw portion provided on an inner peripheral surface on the rear end side of the shaft tube.   The outer peripheral surface of the tail plug is provided with a convex portion that is located between the rear end of the tail plug and the male screw portion and protrudes from the outer peripheral surface, and the top portion of the convex portion is the shaft cylinder. The writing instrument according to claim 1, wherein the writing instrument is pressed against the inner peripheral surface.   The outer peripheral surface of the tail plug is provided with a plurality of ribs that are located on the rear end side of the tail plug and project from the outer peripheral surface, and the ribs extend in the central axis direction of the tail plug. The writing instrument according to claim 1, wherein the writing instrument is arranged at equal intervals on the outer peripheral surface of the tail plug.

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