JP2020082634A - Writing instrument - Google Patents

Abstract

To provide a writing instrument in which a friction body can be firmly fixed to suppress rotation regardless of how a force is applied to the friction body.SOLUTION: There is provided a writing instrument in which a mounting hole that opens rearward in an axial direction is provided at a rear end of a cylindrical body of the writing instrument, and a friction body made of an elastic material is inserted into the mounting hole. An inward protrusion is formed on an inner peripheral surface of the mounting hole, an outward protrusion is formed on an outer peripheral surface of the friction body, and the outward protrusion and the inward protrusion are locked with each other in a front-rear direction. The friction body includes a friction portion that protrudes axially rearward from the rear end of the cylindrical body and a front protrusion on a front end surface of the friction portion. The cylindrical body includes a rear protrusion on the rear end surface of the cylindrical body. The front protrusion and the rear protrusion engage with each other in a rotation direction about a shaft center.SELECTED DRAWING: Figure 5

Description

The present invention relates to a writing instrument. More specifically, the present invention relates to a writing instrument in which a mounting hole that opens axially rearward is provided in a rear end portion of a cylindrical body such as a shaft tube or a cap of the writing tool, and a friction body is inserted into the mounting hole.

Patent Document 1 discloses a soft member mounting structure in which a mounting hole opening axially upward is provided in an upper end portion of a barrel of a writing instrument or a cap or the like, and a soft member is inserted into the mounting hole. There is formed an inward protrusion on the inner peripheral surface of the mounting hole, and an outer protrusion is formed on the outer peripheral surface of the soft member, and the outward protrusion passes over the inward protrusion from above to below. The attachment structure of the members is described.

JP, 2007-144991, A

In the technique disclosed in Patent Document 1, the small diameter portion of the soft member (corresponding to the friction body of the present invention) (corresponding to the insertion portion of the present invention) the outer peripheral surface of the rear end (that is, the small diameter portion and the large diameter of the soft member) On the outer peripheral surface of the portion (corresponding to the friction portion of the present invention) connected to the shoulder portion, an inclined surface-shaped (that is, conical surface-shaped) base portion whose outer diameter gradually increases toward the upper side is formed, When the soft member is inserted into the mounting hole, the base of the inclined surface is pressed against the opening edge of the mounting hole. Depending on how the force is applied to the soft member, the user may experience friction during the friction. There is a risk that it will rotate contrary to the intention of. In particular, when the friction portion has a non-circular cross section, rotation is likely to occur.

The present invention is to solve the above conventional problems, and to provide a writing instrument in which the friction body is firmly fixed regardless of how the force is applied to the friction body and rotation is suppressed during friction. To do.

In the present invention, “rear” refers to the friction body side in the entire writing instrument, and “front” refers to the side opposite to the friction body side. Further, in the present invention, the "pen tip immersive state" means a state in which the pen tip is immersed in the barrel, and the "pen tip protruding state" means that the pen tip projects outside from the front end hole of the barrel. State.

The present invention is a writing instrument in which a mounting hole opening axially rearward is provided at a rear end portion of a cylindrical body such as a shaft cylinder or a cap of a writing tool, and a friction body made of an elastic material is inserted into the mounting hole. The writing instrument forms an inward protrusion on the inner peripheral surface of the mounting hole, forms an outward protrusion on the outer peripheral surface of the friction body, and locks the outward protrusion and the inward protrusion in the front-rear direction. The friction body includes a friction portion projecting axially rearward from a rear end of the tubular body, a front protrusion on a front end surface of the friction portion, and the tubular body includes a rear protrusion on a rear end surface of the tubular body. The writing instrument characterized in that the front protrusion and the rear protrusion engage with each other in a rotational direction about an axis.

According to the present invention, in the writing instrument, an inward protrusion is formed on an inner peripheral surface of the attachment hole, and an outward protrusion is formed on an outer peripheral surface of the friction body, and the outward protrusion and the inward protrusion are engaged in a front-rear direction. The friction body is provided with a friction portion projecting axially rearward from the rear end of the cylindrical body and a front protrusion on the front end surface of the friction portion, and the cylindrical body is formed on the rear end surface of the cylindrical body. A rear protrusion is provided, and the front protrusion and the rear protrusion are engaged with each other in a rotation direction about an axis, respectively, to suppress rotation of the friction body, and to prevent friction regardless of how force is applied to the friction body. The body is firmly fixed and can prevent rotation.

According to the writing instrument of the present invention, the friction body is firmly fixed regardless of how the force is applied to the friction body, and rotation can be suppressed.

It is a longitudinal cross-sectional view of the writing instrument in the first embodiment of the present invention. It is a principal part expanded longitudinal cross-sectional view of FIG. It is a principal part expanded longitudinal cross-sectional view of FIG. FIG. 2 is an enlarged vertical sectional view of an essential part at the time of friction in FIG. FIG. 5A is an enlarged front view of the writing instrument (friction body) according to the first embodiment of the present invention. FIG. 5B is an enlarged side view of the writing instrument (friction body) according to the first embodiment of the present invention. FIG. 5C is a sectional view taken along the line AA of FIG. FIG. 5D is a sectional view taken along the line BB of FIG. It is an enlarged perspective view of the writing instrument (friction body) in 1st Embodiment. FIG. 7A is an enlarged front view of the writing instrument (friction body) according to the second embodiment of the present invention. FIG. 7B is an enlarged side view of the writing instrument (friction body) according to the second embodiment of the present invention. FIG.7(c) is CC sectional view taken on the line of FIG.7(a). FIG.7(d) is the DD sectional view taken on the line of FIG.7(a). It is an expansion perspective view of a writing instrument (friction body) in a 2nd embodiment.

Hereinafter, two embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
1 to 6 show a first embodiment of the present invention.
The writing instrument 1 according to the present embodiment is configured such that a cylinder body 2, a writing body 3 housed in the cylinder body 2, and a pen tip 31 of the writing body 3 can be retracted from a front end hole 21 of the cylinder body 2. And a mechanism.

-Writing body The writing body 3 includes a pen tip 31, an ink containing tube 32 in which the pen tip 31 is press-fitted and fixed in a front end opening portion, a thermochromic ink filled in the ink containing tube 32, and the heat. It comprises a follower (for example, a high-viscosity fluid) that is filled in the rear end of the color-changing ink and advances as the thermochromic ink is consumed.

The nib 31 may be composed of, for example, only a metal ball-point pen tip that rotatably holds a ball at its front end, or a composition made of a synthetic resin pen-tip holder that holds a rear outer surface of the ball-point pen tip. May be. Further, a tail plug having a vent hole through which the ink containing tube 32 and the outside can be ventilated is attached to the rear end opening of the ink containing tube 32. A spring that presses the ball at the front end forward is housed inside the pen tip 31. The spring has a configuration in which a rod portion is provided at the front end portion of a compression coil spring, and the front end of the rod portion is in contact with the ball rear surface. When not writing, the ball is brought into close contact with the inner surface of the inward front end edge portion of the front end of the ballpoint pen tip by the forward biasing of the spring, and the leakage of ink from the front end of the pen tip 31 and the evaporation of ink can be prevented.

-Cylinder 2 is composed of a tapered cylindrical front shaft 2a, a cylindrical intermediate shaft 2b connected to the rear end of the front shaft 2a, and a cylinder connected to the rear end of the intermediate shaft 2b. A rear axle 2c. A slide hole 22 extending in the axial direction is formed in the side wall of the cylindrical body 2 (for example, the side wall of the intermediate shaft 2b and the side wall of the rear shaft 2c). A mounting hole 23 is axially provided at the rear end of the cylindrical body 2 (that is, the rear end of the rear shaft 2c). The friction body 7 made of an elastic material is press-fitted into the mounting hole 23. The friction body 7 is fixed to the outer surface of the rear end of the rear shaft 2c (cylindrical body 2) without interlocking with the axial movement of the operation unit 4. The friction body 7 is provided independently of the operation unit 4. Further, the tubular body of the present invention may be a tubular body such as a cap of a writing instrument.

Rearward Protrusion As shown in FIG. 5, the cylindrical body 2 includes a rearward protrusion 25 on the rear end surface. The rear protrusions 25 in the present embodiment are a pair of triangular protrusions protruding rearward from the rear end surface of the cylindrical body 2. The rear protrusion 25 and a front protrusion 78, which will be described later, are engaged with each other in the rotation direction about the shaft center, so that the rotation about the shaft center of the friction body 7 can be performed regardless of how the force is applied to the friction body 7. Deter. Of course, the shape of the rear protrusion 25 is not limited to the illustrated shape, and may be, for example, a semicircular shape, a quadrangular shape, or another polygonal shape, and the number thereof is not limited.

-Inward projection An annular inward projection 24 is integrally formed on the inner peripheral surface of the mounting hole 23. The inward projection 24 has a guide portion 24a having an inclined surface (that is, a conical surface) whose inner diameter gradually decreases toward the front. Further, the inward projection 24 has a front end face, which is a face perpendicular to the axis, in front of the guide portion 24a. A minimum inner diameter portion 24b having an acute corner is formed between the guide portion 24a and the front end surface.

-Ejecting/retracting mechanism The retracting mechanism is a side slide type retracting mechanism that uses a rotating cam mechanism. The retracting mechanism includes a cam portion formed on the inner surface of the intermediate shaft 2b, a rotating member 5 that engages with the cam portion and contacts the rear end of the writing body 3, and a slide hole 22 that engages with the rotating member 5. It comprises an operating portion 4 protruding further outward in the radial direction, and an elastic body 6 (for example, a compression coil spring) housed in the tubular body 2 and biasing the writing body 3 backward. The retractable mechanism of the present embodiment is a double knock type in which both the pen tip projecting operation and the pen tip retracting operation slide the operating portion 4 forward. The rotating member 5 is obtained by molding a synthetic resin (for example, polyacetal resin).

The cam portion includes a plurality of saw-teeth-shaped cam teeth projecting forward and a plurality of axially extending cam grooves formed between the cam teeth. The rotating member 5 is provided with a plurality of (for example, four) protrusions extending in the axial direction on its outer surface, and the protrusions are engaged with the cam teeth of the cam portion and the cam grooves of the cam portion. On the front end of the shaft portion 43 of the operation portion 4, cam teeth that engage with the rear end of the protrusion of the rotating member 5 are formed integrally or by attaching another member.

-Operation part The operation part 4 is provided with the operation base part 41 projected outward in the radial direction from the slide hole 22 extending in the axial direction of the side wall of the tubular body 2. In addition, the operation portion 4 includes a shaft portion 43 that is connected to the operation base portion 41 and is housed in the cylindrical body 2 so as to be movable in the axial direction, and a clip portion 44 that is connected to the front side of the operation base portion 41. .. The clip portion 44 can hold clothes such as pockets. The operation unit 4 is obtained by a molded body of synthetic resin (for example, polycarbonate resin). The ball portion 42 is provided so as to project from the back surface (inner surface) of the clip portion 44. The operation base portion 41 and the shaft portion 43, the operation base portion 41 and the clip portion 44, and the clip portion 44 and the ball portion 42 are integrally formed by one member or formed by assembling a bisection material.

The operation base 41 is axially movable along the slide hole 22. By pressing the operation base 41 forward, the pen tip 31 of the writing body 3 is configured to be retractable from the front end hole 21 of the tubular body 2.

When the pen tip is retracted, when the operation base 41 of the operation unit 4 is slid forward from the pen tip retracted state against the rearward bias of the elastic body 6, the cam member of the shaft portion 43 of the operation unit 4 causes the rotating member to rotate. 5 is pushed forward and the projection of the rotary member 5 moves forward along the cam groove, the rotary member 5 pushes the rear end of the writing body 3 forward, and the pen tip 31 moves the front end hole 21. It is more exposed to the outside. At this time, due to the contact between the cam teeth of the shaft portion 43 and the protrusion of the rotating member 5, the rotating member 5 rotates by a certain angle with respect to the cam portion. As a result, the protrusion of the rotating member 5 is engaged with the cam teeth of the cam portion, and the pen tip protruding state is maintained.

When the operation base portion 41 of the operation portion 4 is slid forward from the pen tip protruding state, the shaft portion 43 of the operation portion 4 presses the rotating member 5 forward, and the cam teeth of the shaft portion 43 and the protrusion of the rotating member 5 are pushed. The contact of the rotating member 5 causes the rotating member 5 to rotate by a certain angle with respect to the cam portion. As a result, the engagement between the ridge and the cam teeth of the cam portion is released, and the ridge is moved rearward along the cam groove of the cam portion by the biasing of the elastic body 6 to the rear. As the rotating member 5 moves rearward, the writing body 3 moves rearward, so that the pen tip is immersed.

-Frictional Body The frictional body 7 is composed of a friction portion 72 and an insertion portion 74 that is integrally provided in front of the friction portion 72 and is integrally formed of an elastic material. In the present embodiment, the friction body 7 employs a friction discoloring member that rubs the surface of the thermochromic handwriting to thermally discolor the handwriting. The outer surface of the friction portion 72 has a non-circular cross section. (See FIG. 5(c) or FIG. 7(c).) As a matter of course, the cross-sectional non-circular shape is not limited to the illustrated shape, and for example, a triangular shape, a quadrangular shape, a hexagonal shape, or the like may be used. It may be polygonal. This makes it possible to scrape the handwriting with the thermochromic ink only on the portion intended by the user by using an appropriate portion of the friction body, and prevent the color from being discolored more than necessary.

The friction body 7 has an outward projection 75 formed on the outer peripheral surface, and the outward projection 75 and the inward projection 24 are locked in the front-rear direction. Further, the friction body 7 includes a friction portion 72 that projects axially rearward from the rear end of the tubular body 2 and a front protrusion 78 on the front end surface of the friction portion 72. The front protrusion 78 and the rear protrusion 25 are engaged with each other in the rotational direction about the shaft center, respectively, to prevent the friction body 7 from rotating about the shaft center, regardless of how the force is applied to the friction body 7. .. The outward protrusions 75 and the inward protrusions 24 are locked in the front-rear direction, and the front protrusions 78 and the rear protrusions 25 are engaged with each other in the rotational direction about the axis, whereby the friction body 7 is firmly fixed to the cylindrical body 2. Can be fixed.

Front Protrusion As shown in FIG. 5, the friction body 7 includes a front protrusion 78 on the front end surface of the friction portion 72. The front protrusion 78 in the present embodiment is a pair of circumferentially-shaped protrusions that protrude forward from the friction portion 72, and each end portion in the circumferential direction has an inclined surface. In other words, the friction body 7 includes a pair of triangular recesses rearward from the front end surface of the friction portion 72. The front protrusion 78 and the above-mentioned rear protrusion 25 mesh with each other in the rotation direction about the axis, so that the rotation about the axis of the friction body 7 can be performed regardless of how the force is applied to the friction body 7. Suppress. Of course, the shape of the rear protrusion 25 is not limited to the illustrated shape, and may be, for example, a semicircular shape, a quadrangular shape, or another polygonal shape, and the number thereof is not limited.

FIG. 5 is an enlarged view of the writing instrument 1 (friction body 7) in the first embodiment of the present invention, and FIG. 6 is a perspective view of FIG. As shown in FIGS. 5 and 6, when the friction body 7 is attached to the tubular body 2 (rear shaft 2c), the transverse cross-sectional shape of the friction portion 72 exposed from the tubular body 2 is substantially rectangular (see FIG. c)). Specifically, the apex of the rectangle is formed in a circular arc shape in the cross section, and the radius of curvature of the arc is larger at the front end of the friction portion 72 of the friction body 7. As a result, the friction body 7 of the first embodiment of the present invention has a substantially rectangular horizontal cross section, and if the short side of the rectangular horizontal cross section is rubbed, it is possible to concentrate and rub a narrow range. If the long side of the rectangular shape is rubbed, a wide area can be rubbed quickly, and the frictional operation intended by the user can be performed. The cross-sectional shape of the friction portion 72 is not limited to a substantially rectangular shape, and may be an ellipse, a quadrangle, a hexagon, or another polygon.

In addition, preferably, the inner peripheral surface of the mounting hole 23 of the tubular body 2 has a circular cross section, and the friction body 7 is integrally provided continuously from the friction portion 72 to the front and inserted into the mounting hole 23. The outer surface of the insertion portion 74 has a circular cross section, and the outward projection 75 is formed on the outer peripheral surface of the insertion portion 74. As a result, the friction body 7 is stably mounted in the mounting hole 23, and the front protrusion 78 and the rear protrusion 25 can be more firmly meshed with each other in the rotational direction about the axis. However, even if an injection molding gate or the like is provided on the outer surface of the insertion portion 74, the above configuration is satisfied and the above effects are not impeded.

Further, in the friction body 7, preferably, a base 77 is formed on the outer peripheral surface of the rear end of the insertion portion 74, and the base 77 of the insertion portion 74 and the inner peripheral surface of the opening edge of the mounting hole 23 are not in contact with each other during non-friction. Is. As a result, the insertion resistance when the friction body 7 is inserted is reduced, and the assemblability is improved.

Further, it preferably has a contact portion 79 between the base portion 77 of the insertion portion 74 and the inner peripheral surface of the opening edge of the mounting hole 23 when the paper surface 8 is rubbed. As a result, resistance is generated between the base 77 of the insertion portion 74 and the inner peripheral surface of the opening edge of the mounting hole 23, and it is possible to further prevent the friction body 7 from unintentionally rotating around the shaft center during friction. it can.

Further, preferably, the cylindrical body 2 having the friction body 7 inserted therein is detachable from the writing instrument 1. Thereby, when the friction body 7 is worn, it can be easily replaced with a new friction body 7. Further, the user can select and exchange the shape of the friction body 7 that he/she likes and use it. The cylindrical body 2 into which the removable friction body 7 is inserted is attached to the writing instrument 1 by removable screwing or fitting.

In the present embodiment, the elastic material forming the friction body 7 is preferably an elastic synthetic resin (rubber, elastomer), such as silicone resin, SBS resin (styrene-butadiene-styrene copolymer), SEBS resin ( Styrene-ethylene-butylene-styrene copolymer), fluorocarbon resin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM) and the like. The elastic synthetic resin forming the friction body 7 is made of a low-wear elastic material that hardly generates wear debris (erased residue) during friction, as compared with a highly wear-resistant elastic material (for example, an eraser). It is preferable that

-Friction portion The rear surface of the friction portion 72 has a convex curved surface shape. A shoulder portion 73 is formed at the front end of the friction portion 72 so as to come into contact with the opening end of the mounting hole 23 (specifically, the rear end of the rear shaft 2c). The maximum outer diameter of the friction portion 72 is set to be larger than the inner diameter of the mounting hole 23 and smaller than the outer diameter of the rear end of the rear shaft 2c.

-Insertion portion An annular outward protrusion 75 is integrally formed on the outer peripheral surface of the front end portion of the insertion portion 74. The outward protrusion 75 has a guide portion 75a that is an inclined surface (that is, a conical surface) whose outer diameter gradually increases toward the rear. The outward protrusion 75 has a rear end surface that is a surface perpendicular to the axis. An acute angle portion is formed between the guide portion 75a and the rear end surface. The corner portion becomes the maximum outer diameter portion 75b of the outward protrusion 75. That is, the outward protrusion 75 includes a guide portion 75a having an inclined surface whose outer diameter gradually increases toward the rear, and a maximum outer diameter portion 75b formed rearward of the guide portion 75a.

The maximum outer diameter of the outward protrusion 75 is set to be larger than the minimum inner diameter of the inward protrusion 24 and smaller than the inner diameter b of the mounting hole 23 rearward of the inward protrusion 24. In the present embodiment, the maximum outer diameter of the outward protrusion 75 (that is, the outer diameter of the maximum outer diameter portion 75b) is set to 4.9 mm, and the minimum inner diameter of the inward protrusion 24 (that is, the inner diameter of the minimum inner diameter portion 24b) is It is set to 4.1 mm. The difference between the maximum outer diameter of the outward protrusion 75 and the minimum inner diameter of the inward protrusion 24 is preferably in the range of 0.5 mm to 2 mm (preferably 0.5 mm to 1 mm). As a result, the friction body 7 can be reliably prevented from coming off, and the outward protrusion 75 and the inward protrusion 24 can be smoothly crossed over.

An inner hole 71 extending in the axial direction is formed inside the friction body 7. The front end of the inner hole 71 is opened forward in the axial direction. The rear end of the inner hole 71 is located inside the friction portion 72. Due to the inner hole 71, the friction body 7 is formed into a bottomed cylindrical shape having a closed rear end and an open front end. In the present embodiment, since the inner hole 71 is formed at least inward in the radial direction of the outward protrusion 75, when the outward protrusion 75 crosses over the inward protrusion 24, the outward protrusion 75 is elastic inward in the radial direction. Deformation becomes easy.

-An annular space The outer diameter a of the intermediate portion of the insertion portion 74 (that is, the portion between the outward protrusion 75 and the shoulder portion 73) is set smaller than the inner diameter b of the rear portion of the mounting hole 23 relative to the inward protrusion 24. It As a result, when the outward protrusion 75 and the inward protrusion 24 just before the outward protrusion 75 rides over the inward protrusion 24 contact with each other, the outer peripheral surface of the insertion portion 74 rearward of the outward protrusion 75 and the rearward side of the inward protrusion 24. An annular space 76 is formed between the mounting hole 23 and the inner peripheral surface of the mounting hole 23.

As shown in FIG. 2, when the outward protrusion 75 and the inward protrusion 24 are strongly pressed against each other immediately before the outward protrusion 75 rides over the inward protrusion 24, the insertion portion 74 behind the outward protrusion 75 is radially outward. Since the annular space 76 is formed even if the friction body 7 swells due to elastic deformation, the outer peripheral surface of the insertion portion 74 behind the outward protrusion 75 is not strongly pressed against the inner peripheral surface of the mounting hole 23, and the friction body 7 is inserted. There is no risk of wearing resistance. As a result, it is possible to smoothly get over the outward protrusion 75 and the inward protrusion 24. Specifically, the outer diameter a is set to 4.9 mm and the inner diameter b is set to 5.6 mm.

Axial gap As shown in FIG. 3, the axial length A from the shoulder 73 of the friction body 7 to the rear end of the outward projection 75 (that is, the maximum outer diameter portion 75b) is the rear end of the rear shaft 2c. To a front end of the inward protrusion 24 of the mounting hole 23 (that is, the minimum inner diameter portion 24b) is set to be slightly larger than the axial length B (see FIG. 3). As a result, when the outward protrusions 75 pass over the inward protrusions 24, even if the outward protrusions 75 and the inward protrusions 24 slip badly, the outward protrusions 75 can reliably pass over the inward protrusions 24 without applying a lubricant or the like. You can

As shown in FIG. 3, the rear end (that is, the maximum outer diameter portion 75b) of the outward protrusion 75 is the front end (that is, the minimum inner diameter portion 24b) when the friction body 7 is completely inserted into the mounting hole 23. ), and an axial gap C is formed between the front end of the inward protrusion 24 and the rear end of the outward protrusion 75. Specifically, the gap C in the axial direction is effectively in the range of 0.05 mm to 1.0 mm (preferably 0.1 mm to 0.5 mm). Due to the dimension of the axial clearance C, even when the friction body 7 is used, there is no great rattling in the axial direction, and furthermore, when the friction body 7 is inserted, the inward projection 24 and the outward projection 75 can be reliably overridden. In the present embodiment, specifically, the axial length A is set to 8 mm and the axial length B is set to 7.9 mm.

In addition, in a state where the outward protrusion 75 and the inward protrusion 24 have finished moving over, the inward protrusion 24 is pressed against the outer peripheral surface of the insertion portion 74 behind the outward protrusion 75. As a result, it is possible to prevent rattling of the insertion portion 74 in the axial direction and the radial direction. Further, in the state where the ride over of the outward protrusion 75 and the inward protrusion 24 is completed, the rear end of the rear shaft 2c is pressed against the shoulder portion 73. As a result, it is possible to prevent the friction portion 72 from sinking into the mounting hole 23, and to prevent the friction portion 72 from rattling in the radial direction.

<Second Embodiment>
7 and 8 show a second embodiment of the present invention. This is a modification of the first embodiment, and the difference from the first embodiment is the shapes of the rear protrusion 25 and the front protrusion 78. Other configurations and effects are the same as those in the first embodiment, and therefore the description thereof will be omitted.

Rearward Protrusion As shown in FIG. 7, the cylindrical body 2 includes a rearward protrusion 25 on the rear end surface. The rear protrusion 25 in the present embodiment is a circumferential convex portion having one inclined surface protruding rearward from the rear end surface of the cylindrical body 2.

Front Protrusion As shown in FIG. 7, the friction body 7 includes a front protrusion 78 on the front end surface of the friction portion 72. The front protrusion 78 in the present embodiment is a circumferential protrusion having one inclined surface protruding forward from the friction portion 72. The outward protrusions 75 and the inward protrusions 24 are locked in the front-rear direction, and the front protrusions 78 and the rear protrusions 25 are engaged with each other in the rotational direction about the axis, whereby the friction body 7 is firmly fixed to the cylindrical body 2. It can be fixed, and rotation about the shaft center of the friction body 7 is suppressed regardless of how the force is applied to the friction body 7.

DESCRIPTION OF SYMBOLS 1 Writing instrument 2 Cylindrical body 2a Front shaft 2b Intermediate shaft 2c Rear shaft 21 Front end hole 22 Slide hole 23 Mounting hole 24 Inward projection 24a Guide part 24b Minimum inner diameter part 25 Back projection 3 Writing body 31 Pen tip 32 Ink storage tube 4 Operation part 41 Operation base portion 42 Ball portion 43 Shaft portion 44 Clip portion 5 Rotating member 6 Resilient body 7 Friction body 71 Inner hole 72 Friction portion 73 Shoulder portion 74 Insertion portion 75 Outward protrusion 75a Guide portion 75b Maximum outer diameter portion 76 Annular space
77 base
78 Front protrusion 79 Contact part 8 Paper surface A Axial length from front end of friction part to rear end of outward protrusion B Axial length C from rear end of tube to front end of inward protrusion C Axial gap a Outer diameter of the middle part of the attachment part b Inner diameter of the part behind the inward projection of the mounting hole

Claims (3)

A writing instrument comprising a shaft body of a writing instrument, a rear end portion of a tubular body such as a cap, provided with an attachment hole opening rearward in the axial direction, and a friction body made of an elastic material being inserted into the attachment hole.
The writing instrument forms an inward protrusion on the inner peripheral surface of the mounting hole, forms an outward protrusion on the outer peripheral surface of the friction body, and the outward protrusion and the inward protrusion are locked in the front-rear direction,
The friction body includes a friction portion projecting axially rearward from a rear end of the cylindrical body, and a front protrusion on a front end surface of the friction portion,
The tubular body includes a rear protrusion on a rear end surface of the tubular body,
The writing instrument characterized in that the front protrusion and the rear protrusion engage with each other in a rotational direction about an axis. The writing instrument according to claim 1, wherein an outer surface of the friction portion of the friction body has a non-circular cross section. The inner peripheral surface of the mounting hole of the cylindrical body has a circular cross section, and the friction body includes an insertion portion that is integrally connected forward from the friction portion and that is inserted into the attachment hole. The writing instrument according to claim 1 or 2, wherein an outer surface of the insertion portion has a circular cross-sectional shape, and an outward projection is formed on an outer peripheral surface of the insertion portion.

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