JP2005262770A - Writing instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a user with a weak hand force to easily remove a plug when the plug is removed from a shaft cylinder, and to surely recognize finishing of screw clamping. <P>SOLUTION: An opening part is provided on the front end of the shaft cylinder 2 made of a synthetic resin. A female screw 21 is integrally formed on the inner peripheral face of the opening of the shaft cylinder 2. A male screw 31 which can be screwed to the female screw 21 is integrally formed on the outer peripheral face of the plug 3 made of a synthetic resin. The shaft cylinder 2 and the plug 3 are freely removably constituted by the screwing. A step part 33 with which the front end of the opening of the shaft cylinder 2 is brought into contact when the shaft cylinder 2 and the plug 3 are screwed together is integrally formed on the outer peripheral face of the plug 3 more front from the male screw 31. When a fastening torque with a specified torque or more is applied on the female screw 21 of the shaft cylinder 2 and the male screw 31 of the plug 3, the screw thread of the female screw 21 and the screw thread of the male screw 31 get over each other, and the female screw 21 and the male screw 31 temporarily rotate in vain. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a writing instrument. More specifically, the present invention relates to a writing instrument including a shaft tube and a plug body (for example, a pen tip holder, a tail plug, etc.) that is detachable at an opening of the shaft tube. In the present invention, “front” refers to the opening side of the shaft tube and the stepped portion side of the plug, and “rear” refers to the opposite side thereof.

Conventionally, with respect to a writing instrument that can be refilled with ink in the shaft cylinder or replaced with an ink cartridge in the shaft cylinder, for example, Patent Document 1 discloses a part of the shaft cylinder in order to facilitate division and fastening of the shaft cylinder. Is a writing instrument in which the outer peripheral portion of at least one end of the shaft cylinder is covered with an elastic body.

JP 2003-39878 A

The writing instrument of the above-mentioned patent document 1 is prevented from slipping when tightened with an elastic body, so that it is easy to tighten the screw, but it is easy to cause overtightening of the screw. If the screw is overtightened, when the shaft tube is divided, it may be difficult for a user with weak hand strength to divide the shaft tube (that is, to remove the plug from the shaft tube in the present invention). Further, the writing instrument of Patent Document 1 is unclear how much the user should tighten the screw, and tends to cause overtightening of the screw or insufficient tightening of the screw.

The present invention solves the above-mentioned conventional problems, prevents overtightening of the screw, and when removing the plug body from the barrel, it is easy to remove even for users with weak hand power, It is intended to provide a writing instrument that allows the user to reliably recognize the end of screw tightening.

[1] In the present invention, an opening is provided at the front end of the shaft tube 2 made of synthetic resin, a female screw portion 21 is integrally formed on the inner peripheral surface of the opening of the shaft tube 2, and a plug body made of synthetic resin. 3, a male screw portion 31 that can be screwed together with the female screw portion 21 is integrally formed, and the shaft tube 2 and the plug body 3 are configured to be detachable by the screwing, and the male screw portion 31. A writing instrument in which a stepped portion 33 with which the front end of the opening of the shaft tube 2 abuts when the shaft tube 2 and the plug body 3 are screwed together is formed integrally on the outer peripheral surface of the plug body 3 at the front. When a predetermined or higher tightening torque is applied to the female screw portion 21 of the shaft tube 2 and the male screw portion 31 of the plug body 3, the screw thread of the female screw portion 21 and the screw thread of the male screw portion 31 are It is a requirement that the female threaded portion 21 and the male threaded portion 31 are configured so as to slip over each other and temporarily idle (claim 1).

When a predetermined or higher tightening torque is applied between the female screw portion 21 of the shaft tube 2 and the male screw portion 31 of the plug body 3, the female screw portion 21 of the shaft tube 2 and the male screw of the plug body 3 are used. Since the portion 31 temporarily idles (that is, idles), it is possible to prevent the female screw portion 21 of the shaft tube 2 and the male screw portion 31 of the plug body 3 from being tightened tightly (overtightening of the screw). As a result, when removing the barrel 2 from the plug 3, even a user with weak hand strength can easily remove it. Further, when the thread of the female threaded portion 21 of the shaft cylinder 2 and the thread of the male threaded portion 31 of the plug body 3 get over each other, a jumping sound (so-called patching noise) is generated and tightening torque is reduced. A sudden decrease can be felt in response, and the user can be surely aware of the end of the tightening operation.

[2] In the writing instrument according to the first aspect, the tightening torque during idling (that is, the maximum tightening torque immediately before the female screw portion 21 and the male screw portion 31 idle) is 3 kgf · cm to 10 kgf · cm (preferably Is preferably in the range of 3 kgf · cm to 6 kgf · cm (Claim 1).

If the tightening torque during idling is less than 3 kgf · cm, insufficient screw tightening may occur, and the screwed state between the shaft tube 2 and the plug body 3 may be loosened due to the use of the writing instrument. On the other hand, if the tightening torque during idling is greater than 10 kgf · cm (preferably 6 kgf · cm), overtightening of the screw occurs, making it difficult to remove the plug 3 from the shaft cylinder 2.

[3] In the writing instrument according to claim 1 or 2, the maximum outer diameter of the shaft tube 2 and the maximum outer diameter of the plug body 3 are in a range of 15 mm to 30 mm (preferably 20 mm to 25 mm). 3) is effective. That is, in the writing instrument in which the maximum outer diameter D1 of the shaft tube 2 and the maximum outer diameter D2 of the plug body 3 are within the above ranges, the configuration of claim 1 or 2 is effective, Insufficient tightening can be prevented more reliably.

The writing instrument of claim 1 prevents overtightening of the screw, and when removing the plug body from the barrel, it is easy to remove even if the user has weak hand power, and the user reliably recognizes the end of screw tightening. can do.

The writing instrument of claim 2 can further prevent overtightening of the screw and insufficient tightening of the screw.

The writing instrument of claim 3 can more reliably prevent overtightening of the screw and insufficient tightening of the screw.

The best mode for carrying out the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention.
The writing instrument 1 according to the present embodiment includes a shaft cylinder 2 in which an ink occlusion body 5 is accommodated, and a pen tip holder 3 (plug body) configured to be detachable by screwing into an opening of the shaft cylinder 2. . A nib 4 (for example, a resin processed body of a fiber bundle) is press-fitted and held in the nib holder 3, and an ink occlusion body 5 (for example, a fiber bundle of fiber bundle) that holds ink by capillary force in the shaft cylinder 2. A heat-bonded processed body, a resin processed body of fiber bundles, and the like) are accommodated. The rear end portion of the nib 4 is connected to the front end portion of the ink occlusion body 5 in a stab-like manner, while the front end portion of the nib 4 protrudes to the outside. By removing the pen tip holder 3 from the opening of the shaft cylinder 2, the ink storage body 5 in the shaft cylinder 2 is directly replenished with ink or replaced with another ink storage body 5 sufficiently impregnated with ink. can do.

The shaft cylinder 2 and the nib holder 3 are cylindrical bodies obtained by injection molding of synthetic resin (for example, polypropylene, polyethylene, polycarbonate, polyethylene terephthalate, polyacetal, nylon, ABS resin, etc.). In the present embodiment, the shaft cylinder 2 and the nib holder 3 are made of polypropylene in that they are excellent in flexibility and the screw threads are not damaged even when idling.

An internal thread portion 21 is integrally formed on the inner surface of the opening of the shaft tube 2, and an airtight fitting portion 22 is integrally formed behind the internal thread portion 21. In the present embodiment, the airtight fitting portion 22 on the inner surface of the opening of the shaft cylinder 2 is formed of an annular protrusion.

The nib holder 3 has a tapered front part for holding the nib 4, a rear part that can be inserted into the opening of the shaft cylinder 2, and a collar part formed between the front part and the rear part. It is arranged continuously. The rear surface of the flange portion is a stepped portion 33 that can be press-contacted with the front end of the opening of the shaft tube 2.

A male screw portion 31 is integrally formed on the outer peripheral surface of the pen tip holder 3 behind the stepped portion 33 (that is, the outer peripheral surface of the rear portion of the pen tip holder 3), and is airtight behind the male screw portion 31. The fitting part 32 is formed integrally. In the present embodiment, the airtight fitting portion 32 on the outer peripheral surface of the nib holder 3 is formed of an annular smooth surface.

As shown in FIG. 2, when the male thread portion 31 of the nib holder 3 is screwed into the female thread portion 21 of the opening of the shaft cylinder 2, the thread of the male thread portion 31 and the thread of the female thread portion 21 are Are engaged, and the step portion 33 of the nib holder 3 and the front end of the shaft tube 2 are pressed against each other in the front-rear direction.

If the tightening torque of the screw is further increased from the state of FIG. 2, the thread of the male thread 31 and the thread of the female thread 21 get over each other as shown in FIG. The engagement between the screw threads is released, and the male screw portion 31 and the female screw portion 21 idle. At that time, a sound (patching sound) due to overcoming of the threads is generated, and the tightening torque is rapidly reduced. As a result, it is possible to confirm the end of the screw tightening when the overtightening of the screw can be prevented. The tightening torque during idling is set to an appropriate range of 3 kg · cm to 6 kg · cm, and at least the tightening torque at the end of screwing does not exceed the idling range. Further, the torque (return torque) when the pen tip holder 3 (plug body) screwed to the shaft cylinder 2 is removed from the shaft cylinder 2 does not exceed the tightening torque during idling. In this example, the tightening torque was measured using a torque meter manufactured by Tohnichi Corporation.

The maximum outer diameter D1 of the shaft cylinder 2 and the maximum outer diameter D2 of the nib holder 3 are measured in a removed state before screwing. In this embodiment, D1 and D2 are set in a range of 20 mm to 25 mm.

The female screw portion 21 is obtained by forcibly removing the core pin during injection molding. Therefore, the thread of the female screw portion 21 is an undercut portion. The rear surface of the thread of the female screw portion 21 is formed in an inclined surface shape having a smaller outer diameter toward the rear so that the core pin can be easily removed. An inclination angle α of the rear surface of the thread of the female screw portion 21 (that is, an angle formed between the rear surface of the thread and the axis P) is set in a range of 20 degrees to 45 degrees. Thereby, the mold release at the time of injection molding becomes smooth, and at the same time, it is easy to get over the threads (that is, idling) when an excessive tightening torque is applied. If the inclination angle α is smaller than 20 degrees, the tightening torque during idling decreases, screw tightening is insufficient, and the screwed state between the shaft tube 2 and the plug 3 may be loosened due to the use of a writing instrument. . On the other hand, when the inclination angle α is larger than 45 degrees, the tightening torque at the time of idling increases, the screw is excessively tightened, and it may be difficult to remove the plug body 3 from the shaft cylinder 2.

The difference between the outer diameter of the thread apex of the male screw part 31 and the inner diameter of the thread apex of the female screw part 21 is set to 0.2 mm to 0.5 mm (preferably 0.3 mm to 0.4 mm). Is done. As a result, an appropriate tightening torque during idling is obtained. If the difference between the outer diameter of the screw thread apex of the male screw part 31 and the inner diameter of the screw apex of the female screw part 21 is smaller than 0.2 mm, the screwed state cannot be maintained and may be easily loosened. is there. On the other hand, if the difference between the outer diameter of the screw thread apex of the male screw part 31 and the inner diameter of the screw apex of the female screw part 21 is greater than 0.5 mm, the tightening torque during idling increases and the screw is overtightened. May occur. The outer diameter of the thread apex and the inner diameter of the thread apex are measured in a state where the shaft cylinder 2 and the nib holder 3 (plug body) are removed.

In addition, when the female screw portion 21 and the male screw portion 31 are idle, the screw threads cross each other, so that the airtight fitting portions 22 and 32 (that is, the annular protrusion and the annular smooth surface) are in a close contact state. They just rotate without moving back and forth, and the airtight state is maintained. Further, since the airtight fitting portions 22 and 32 are located behind the male screw portion 31 and the female screw portion 21, the effect of deformation of the female screw portion 21 in the radially outward direction during idle rotation, An appropriate airtight state is maintained without being affected by the radially inward deformation of the screw portion 31.

In the present embodiment, the pen tip holder is adopted as the plug, but in addition to this, a member (for example, a tail plug) that closes the opening of the shaft tube 2 and does not include the pen tip may be used.

In the present invention, a non-slip portion made of unevenness or an elastic material may be provided on the outer surface of the shaft tube 2 or the plug body 3.

It is a principal part longitudinal cross-sectional view of the Example of this invention. It is the A section enlarged view at the time of screwing of FIG. It is the A section enlarged view at the time of idling of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Writing instrument 2 Shaft cylinder 21 Female thread part 22 Airtight fitting part (annular protrusion)
3 Nib holder (plug)
31 Male thread part 32 Airtight fitting part (annular smooth surface)
33 Step part 4 Nib 5 Ink occlusion body D1 Maximum outer diameter of shaft cylinder D2 Maximum outer diameter of plug body

Claims (3)

An opening is provided at the front end of the shaft barrel made of synthetic resin, a female screw portion is integrally formed on the inner peripheral surface of the opening portion of the shaft barrel, and the female screw portion is formed on the outer peripheral surface of the synthetic resin plug body. A threaded male screw part is integrally formed, and the shaft cylinder and the plug body are detachable by the screwing, and the shaft cylinder and the plug are formed on the outer peripheral surface of the plug body in front of the male screw part. A writing instrument integrally formed with a step portion that abuts the front end of the opening of the shaft cylinder when screwing the body,
When a predetermined or higher tightening torque is applied to the female thread part of the shaft tube and the male thread part of the plug, the thread of the female thread part and the thread of the male thread part get over each other, and the female thread A writing instrument, wherein the portion and the male screw portion are configured to temporarily idle. The writing instrument according to claim 1, wherein the tightening torque during idling is in a range of 3 kgf · cm to 10 kgf · cm. The writing instrument according to claim 1 or 2, wherein a maximum outer diameter of the shaft cylinder and a maximum outer diameter of the plug body are in a range of 15 mm to 30 mm.

Images