JP4712646B2 - Soft member mounting structure - Google Patents

Description

The present invention relates to a flexible member mounting structure. More specifically, the present invention relates to a soft member mounting structure in which a mounting hole that opens upward in the axial direction is provided at the upper end of a cylindrical body such as a shaft cylinder or a cap of a writing instrument, and a soft member is inserted into the mounting hole. In the present invention, “upper” refers to the mounting hole side in the cylindrical body, and refers to the larger diameter portion side in the soft member. On the other hand, in the present invention, “lower” refers to the opposite side of the mounting hole in the cylindrical body, and refers to the small diameter portion side in the soft member.

Regarding a conventional soft member mounting structure, Patent Document 1 discloses a structure in which an eraser is mounted on a pencil cap.

Japanese Utility Model Publication No. 51-139030

However, the conventional soft member mounting structure may cause the soft member to fall out of the mounting hole when the elasticity of the soft member decreases with time, and a large pushing force when the soft member is pressed into the mounting hole. Is necessary and the installation work is not easy.

The present invention solves the above-mentioned conventional problems, and it is intended to provide a soft member mounting structure that can surely prevent the soft member from falling off and that facilitates the mounting work of the soft member. It is.

(Configuration 1)
The present invention provides an attachment hole 2 that opens upward in the axial direction at the upper end of a cylinder 1 such as a shaft cylinder or a cap of a writing instrument, and the attachment of the soft member 3 by inserting the soft member 3 into the attachment hole 2. In the structure, the inward projection 21 is formed on the inner peripheral surface of the mounting hole 2, and the outward projection 51 is formed on the outer peripheral surface of the soft member 3, and the outward projection 51 climbs over the inward projection 21 from above. (Configuration 1) is a requirement.

In the structure for attaching the soft member of the configuration 1, when the soft member 3 is inserted into the attachment hole 2, the outward projection 51 rides over the inward projection 21 from the upper side to the lower side. 3, the soft member 3 does not fall out of the mounting hole 2 due to the strong engagement between the outward projection 51 and the inward projection 21.

(Configuration 2)
In the above configuration, when the soft member 3 is inserted into the mounting hole 2, the annular space 6 is provided between the inner peripheral surface of the upper portion of the mounting hole 2 than the inward projection 21 and the outer peripheral surface of the soft member 3 ( Configuration 2) is preferred.

The soft member mounting structure of the configuration 2 is configured such that the annular space 6 is provided between the inner peripheral surface of the mounting hole 2 above the inward protrusion 21 and the outer peripheral surface of the soft member 3 so that the outward protrusion 51 and the inward protrusion are inward. Since the outer peripheral surface of the soft member 3 bulging and deforming radially outward when pressed against the projection 21 is not strongly pressed against the inner peripheral surface of the mounting hole 2, the outward projection 51 and the inward projection 21 It is possible to get over smoothly.

If the annular space 6 is not provided, the outer peripheral surface of the soft member 3 bulging and deforming radially outward when the outward projection 51 and the inward projection 21 are brought into pressure contact with each other is formed in the mounting hole 2. There is a possibility that the outer protrusion 51 and the inward protrusion 21 cannot be smoothly passed over because the outward protrusion 51 gets over the inward protrusion 21 and is strongly pressed against the peripheral surface.

In addition, the soft member mounting structure of the configuration 2 is configured such that the soft member 3 is inserted into the mounting hole 2 until the outward protrusion 51 and the inward protrusion 21 abut immediately before the outward protrusion 51 gets over the inward protrusion 21 by the annular space 6. Can be inserted quickly, and the attachment work of the soft member 3 becomes easy.

(Configuration 3)
In the above configuration, the soft member 3 has a large-diameter portion 4 that protrudes upward in the axial direction from the upper end of the cylindrical body 1, and a small-diameter that is integrally connected downward from the large-diameter portion 4 and inserted into the mounting hole 2. In the state in which the soft member 3 is inserted into the mounting hole 2, the opening end of the mounting hole 2 and the lower end of the large-diameter portion 4 are contacted in the axial direction, and the inward protrusion 21 and the outward protrusion 51 It is preferable to provide an axial gap C therebetween (Configuration 3).

The attachment structure of the soft member of the said structure 3 can control the excessive penetration | invasion in the attachment hole 2 of the soft member 3 because the attachment hole 2 opening end and the large diameter part 4 lower end contact | abut in an axial direction. Further, the soft member mounting structure of the configuration 3 has the axial gap C formed between the inward projection 21 and the outward projection 51, so that when the outward projection 51 gets over the inward projection 21, Even if the sliding with the inward projection 21 is poor, the outward projection 51 can reliably get over the inward projection 21. If an axial gap C is not provided between the inward projection 21 and the outward projection 51, when the outward projection 51 gets over the inward projection 21, if the slip between the outward projection 51 and the inward projection 21 is bad, the outward projection There is a possibility that 51 cannot reliably get over the inward projection 21.

The axial gap C is preferably in the range of 0.05 mm to 1.0 mm (preferably 0.1 mm to 0.5 mm). Accordingly, there is no large backlash in the axial direction of the soft member 3 after being attached to the attachment hole 2, and a smooth ride over the outward projection 51 and the inward projection 21 can be obtained.

(Configuration 4)
In the above configuration, it is preferable that an axial inner hole 31 is formed inside the soft member 3 and at least the inner hole 31 is located radially inward of the outward projection 51 (configuration 4). Thereby, when the outward projection 51 gets over the inward projection 21, the soft member 3 easily elastically deforms inward in the radial direction, so that it is possible to get over smoothly.

(Configuration 5)
In the above configuration, it is preferable that the inward projection 21 is in pressure contact with the outer peripheral surface of the soft member 3 in a state where the soft member 3 is inserted into the mounting hole 2 (Configuration 5). Thereby, the radial and axial backlash of the soft member 3 after being inserted into the mounting hole 2 can be prevented.

(Configuration 6)
In the above configuration, it is preferable that the inward projection 21 is annular and the outward projection 51 is annular (configuration 6). Thereby, prevention of dropout of the soft member 3 from the mounting hole 2 is further ensured. If one of the inward protrusion 21 and the outward protrusion 51 is composed of a plurality of protrusions dispersed in a circumferential shape, the prevention of the soft member 3 from falling off from the mounting hole 2 is insufficient.

(Configuration 7)
In the above configuration, the inward projection 21 includes a guide portion 21a having an inclined surface whose inner diameter decreases as it goes downward, and a minimum inner diameter portion 21b formed below the guide portion 21a, and the minimum inner diameter portion 21b is inward. It is preferable to be located at the lower end of the protrusion 21 (Configuration 7). Thereby, even if a force for dropping the soft member 3 is applied, the minimum inner diameter portion 21b of the inward projection 21 and the outward projection 51 are firmly engaged, so that the soft member 3 can be more reliably prevented from falling off. . The minimum inner diameter portion 21b refers to the minimum inner diameter portion of the inward projection 21.

(Configuration 8)
In the above configuration, the cylindrical body 1 and the inward projection 21 are integrally formed by molding a synthetic resin, and a recess 23 that opens downward is formed between the minimum inner diameter portion 21b of the inward projection 21 and the inner surface of the mounting hole 2. The minimum inner diameter portion 21b is preferably protruded downward (Configuration 8). Thereby, when the outward projection 51 at the time of insertion of the soft member 3 gets over the inward projection 21, the minimum outer diameter portion of the inward projection 21 is easily elastically deformed radially outward, so that it is possible to get over smoothly. The pushing force when the soft member 3 is inserted into the mounting hole 2 can be reduced, and there is no possibility of forming defects such as sink marks on the outer surface of the cylindrical body 1 where the inward projection 21 is located.

According to claim 1, it is possible to reliably prevent the soft member from falling off.

According to claim 2, it is possible to smoothly get over the outward projection and the inward projection.

According to the third aspect, excessive immersing of the soft member into the mounting hole can be restricted, and even if the sliding between the outward projection and the inward projection is bad, the outward projection and the inward projection can be reliably overcome. .

According to the fourth aspect, when the outward protrusion gets over the inward protrusion, the soft member is easily elastically deformed radially inward, so that the smooth protrusion can be achieved.

According to the fifth aspect, it is possible to further prevent backlash in the radial direction and the axial direction of the soft member after being inserted into the mounting hole.

According to the sixth aspect, prevention of the soft member from falling off the mounting hole is further ensured.

According to the seventh aspect, it is possible to more reliably prevent the soft member from falling off.

According to the eighth aspect, when the outward protrusion gets over the inward protrusion, it is possible to get over smoothly, and there is no possibility of forming defects such as sink marks on the outer surface of the cylindrical body where the inward protrusion is located.

(First embodiment)
1 to 3 show a first embodiment of the present invention.
The attachment structure of the soft member according to the present embodiment includes a cylindrical body 1 provided with an attachment hole 2 at an upper end portion, and a soft member 3 inserted into the attachment hole 2 of the cylindrical body 1.

-Tube body The tube body 1 is obtained by injection molding or extrusion molding of a synthetic resin (for example, polycarbonate). As for the said cylinder 1, the cap which can be attached or detached to the pen tip side of a shaft cylinder of a writing instrument, or a shaft cylinder is mentioned, for example. A mounting hole 2 that opens upward in the axial direction is formed at the upper end of the cylindrical body 1. The mounting hole 2 is formed on the closed end side of the cap when the cylindrical body 1 is a cap. When the cylindrical body 1 is a shaft cylinder, the mounting hole 2 is the end opposite to the pen tip (the tail end of the shaft cylinder). ). The mounting hole 2 has a circular cross section.

Inward protrusion An annular inward protrusion 21 is integrally formed on the inner peripheral surface of the mounting hole 2. The inward projection 21 has a guide portion 21a formed of an inclined surface (that is, a conical surface) whose inner diameter gradually decreases as it goes downward. Further, the inward projection 21 has a lower end surface made of a surface perpendicular to the axis below the guide portion 21a. A minimum inner diameter portion 21b having an acute corner portion is formed between the guide portion 21a and the lower end surface.

Ribs A plurality of ribs 22 extending in the axial direction are integrally formed on the inner surface of the mounting hole 2 below the inward projection 21. In a state in which the outward projection 51 and the inward projection 21 have been overcome, the rib 22 comes into pressure contact with the outward projection 51 of the soft member 3, and the rotation of the soft member 3 is prevented.

Soft member The soft member 3 includes a large-diameter portion 4 and a small-diameter portion 5 integrally provided below the large-diameter portion 4 and is integrally formed of an elastic material. The soft member 3 is made of an elastic material such as synthetic rubber or elastomer. In the present embodiment, the soft member 3 employs a friction discoloration member that rubs the surface of the thermochromic handwriting to thermally discolor the handwriting. In addition to this, the soft member 3 may be an eraser or an input member of an input pen used for a portable information terminal.

Large diameter portion The upper surface of the large diameter portion 4 has a convex curved surface. At the lower end of the large-diameter portion 4, a shoulder portion 41 is formed that can come into contact with the opening end of the mounting hole 2 (specifically, the upper end of the cylindrical body 1). The maximum outer diameter of the large diameter portion 4 is set to be larger than the inner diameter of the mounting hole 2 and smaller than the outer diameter of the upper end of the cylindrical body 1.

Small-diameter portion An annular outward projection 51 is integrally formed on the outer peripheral surface of the lower end portion of the small-diameter portion 5. The outward projection 51 has a guide portion 51a formed of an inclined surface (that is, a conical surface) whose outer diameter gradually increases toward the upper side. The outward projection 51 has an upper end surface that is a surface perpendicular to the axis. An acute corner is formed between the guide 51a and the upper end surface. The corner portion becomes the maximum outer diameter portion 51 b of the outward projection 51. That is, the outward projection 51 includes a guide portion 51a formed of an inclined surface whose outer diameter gradually increases as it goes upward, and a maximum outer diameter portion 51b formed above the guide portion 51a.

The maximum outer diameter of the outward protrusion 51 is set larger than the minimum inner diameter of the inward protrusion 21 and smaller than the inner diameter b of the mounting hole 2 above the inward protrusion 21. In the present embodiment, the maximum outer diameter of the outward projection 51 (that is, the outer diameter of the maximum outer diameter portion 51b) is set to 4.9 mm, and the minimum inner diameter of the inward projection 21 (that is, the inner diameter of the minimum inner diameter portion 21b) is It is set to 4.1 mm. The difference between the maximum outer diameter of the outward projection 51 and the minimum inner diameter of the inward projection 21 is preferably in the range of 0.5 mm to 2 mm (preferably 0.5 mm to 1 mm). Thereby, the soft member 3 can be reliably prevented from falling off, and the outward projection 51 and the inward projection 21 can be smoothly climbed over.

An inner hole 31 extending in the axial direction is formed in the soft member 3. The lower end of the inner hole 31 is opened downward in the axial direction. The upper end of the inner hole 31 is located inside the large diameter portion 4. Due to the inner hole 31, the soft member 3 is formed in a bottomed cylindrical shape with the upper end closed and the lower end opened. In the present embodiment, since the inner hole 31 is formed at least radially inward of the outward projection 51, the outward projection 51 is elastic inward in the radial direction when the outward projection 51 gets over the inward projection 21. Deformation is easy.

Further, the outer peripheral surface of the front end portion of the small diameter portion 5 (that is, the outer peripheral surface of the connecting portion of the small diameter portion 5 and the shoulder portion 41 of the large diameter portion 4) has an inclined surface shape in which the outer diameter gradually increases toward the upper side. A base 52 having a conical shape is formed. When the soft member 3 is inserted into the mounting hole 2, the inclined base 52 is brought into pressure contact with the opening edge of the mounting hole 2 and the wobbling of the soft member 3 in the radial direction is suppressed.

The outer diameter a of the intermediate portion of the small-diameter portion 5 (that is, the portion between the outward projection 51 and the inclined base 52) is larger than the inner diameter b of the mounting hole 2 above the inward projection 21. Set small. Thereby, when the outward protrusion 51 and the inward protrusion 21 immediately before the outward protrusion 51 gets over the inward protrusion 21 abuts, the outer peripheral surface of the small-diameter portion 5 above the outward protrusion 51 and the upward protrusion 21 above. An annular space 6 is formed between the inner peripheral surface of the mounting hole 2. As shown in FIG. 2, when the outward projection 51 and the inward projection 21 are strongly pressed immediately before the outward projection 51 gets over the inward projection 21, the small-diameter portion 5 above the outward projection 51 is radially outward. Even if it swells due to elastic deformation, since the annular space 6 is formed, the outer peripheral surface of the small-diameter portion 5 above the outward projection 51 is not strongly pressed against the inner peripheral surface of the mounting hole 2, and the soft member 3 is inserted. There is no risk of time resistance. As a result, it is possible to smoothly get over the outward projection 51 and the inward projection 21. Specifically, the outer diameter a is set to 4.9 mm, and the inner diameter b is set to 5.6 mm.

Axial gap A The length A in the axial direction from the shoulder 41 of the soft member 3 to the upper end of the outward projection 51 (that is, the maximum outer diameter portion 51b) is from the upper end of the cylindrical body 1 to the inward projection 21 of the mounting hole 2. It is set slightly larger than the axial length B to the lower end (that is, the minimum inner diameter portion 21b) (see FIG. 1). Thereby, when the outward projection 51 gets over the inward projection 21, the outward projection 51 can surely get over the inward projection 21 even if the outward projection 51 and the inward projection 21 slip poorly. As shown in FIG. 3, the upper end of the outward projection 51 (that is, the maximum outer diameter portion 51b) is the lower end of the inward projection 21 (that is, the minimum inner diameter portion 21b) after the insertion of the soft member 3 into the mounting hole 2 is completed. A gap C in the axial direction is formed between the lower end of the inward projection 21 and the upper end of the outward projection 51. Specifically, the axial gap C is effectively in the range of 0.05 mm to 1.0 mm (preferably 0.1 mm to 0.5 mm). Due to the size of the gap C in the axial direction, there is no large backlash in the axial direction even when the soft member 3 is used, and the inward projection 21 and the outward projection 51 can be reliably overcome when the soft member 3 is inserted. . 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.

-Insertion of a soft member The insertion process of the soft member 3 of this Embodiment is demonstrated according to drawing.
As shown in FIG. 1, the lower end of the small diameter portion 5 of the soft member 3 is inserted into the upper end opening of the mounting hole 2 of the cylindrical body 1.

Further, when the small diameter portion 5 is inserted into the mounting hole 2, the guide portion 51 a of the outward projection 51 of the small diameter portion 5 of the soft member 3 comes into contact with the guide portion 21 a of the inward projection 21 of the mounting hole 2. As shown in FIG. 2, immediately before the outward projection 51 gets over the inward projection 21, the outer peripheral surface of the small diameter portion 5 is bulged and deformed outward in the radial direction. At this time, since the annular space 6 exists between the inner peripheral surface of the mounting hole 2 and the outer peripheral surface of the small diameter portion 5, the outer peripheral surface of the small diameter portion 5 that has bulged and deformed is not strongly pressed against the inner peripheral surface of the mounting hole 2. Thereby, the insertion of the soft member 3 is not hindered, and the outer protrusion 51 and the inward protrusion 21 can smoothly get over.

As shown in FIG. 3, an axial gap C is formed between the upper end of the outward projection 51 and the lower end of the inward projection 21 in the state where the outward projection 51 and the inward projection 21 have been overcome. . Thereby, even if the slip between the outward projection 51 and the inward projection 21 is bad, the outward projection 51 and the inward projection 21 can be reliably overcome without applying a lubricant or the like. In addition, in the state in which the outward projection 51 and the inward projection 21 have been overcome, the inward projection 21 is pressed against the outer peripheral surface of the small-diameter portion 5 above the outward projection 51. Thereby, backlash of the small diameter part 5 in the axial direction and the radial direction can be prevented. In addition, the upper end of the cylindrical body 1 is in pressure contact with the shoulder 41 and the base 52 in a state where the outward projection 51 and the inward projection 21 have been overcome. Thereby, the immersion of the large diameter portion 4 into the mounting hole 2 can be prevented, and the radial play of the large diameter portion 4 can be prevented. In addition, in a state where the outward projection 51 and the inward projection 21 have been overcome, the rib 22 comes into pressure contact with the outer surface of the outward projection 51, and the rotation of the soft member 3 is prevented.

(Second Embodiment)
4 to 6 show a second embodiment of the present invention.
The attachment structure of the soft member according to the present embodiment includes a cylindrical body 1 provided with an attachment hole 2 at an upper end portion, and a soft member 3 inserted into the attachment hole 2 of the cylindrical body 1.

-Cylinder The said cylinder 1 is obtained by the injection molding of a synthetic resin (for example, polypropylene). As for the said cylinder 1, the cap which can be attached or detached to the pen tip side of a shaft cylinder of a writing instrument, or a shaft cylinder is mentioned, for example. A mounting hole 2 that opens upward in the axial direction is formed at the upper end of the cylindrical body 1. The mounting hole 2 is formed on the closed end side of the cap when the cylindrical body 1 is a cap. When the cylindrical body 1 is a shaft cylinder, the mounting hole 2 is the end opposite to the pen tip (the tail end of the shaft cylinder). ). The mounting hole 2 has a circular cross section.

Inward protrusion An annular inward protrusion 21 is integrally formed on the inner peripheral surface of the mounting hole 2. The inward projection 21 has a guide portion 21a formed of an inclined surface (that is, a conical surface) whose inner diameter gradually decreases as it goes downward. A minimum inner diameter portion 21b is formed at the lower end of the inward projection 21 below the guide portion 21a. A recess 23 that opens downward is formed between the minimum inner diameter portion 21b of the inward projection 21 and the inner peripheral surface of the mounting hole 2, and the minimum inner diameter portion 21b protrudes downward. Due to the recess 23, it is possible to avoid the occurrence of molding defects such as sink marks on the outer surface of the cylindrical body 1 where the inward projection 21 is located.

Soft member The soft member 3 includes a large-diameter portion 4 and a small-diameter portion 5 integrally provided below the large-diameter portion 4 and is integrally formed of an elastic material. The soft member 3 is made of an elastic material such as synthetic rubber or elastomer. In the present embodiment, the soft member 3 employs a friction discoloration member that rubs the surface of the thermochromic handwriting to thermally discolor the handwriting. In addition to this, the soft member 3 may be an eraser or an input member of an input pen used for a portable information terminal.

Large diameter portion The upper surface of the large diameter portion 4 has a convex curved surface. At the lower end of the large-diameter portion 4, a shoulder portion 41 is formed that can come into contact with the opening end of the mounting hole 2 (specifically, the upper end of the cylindrical body 1). The maximum outer diameter of the large diameter portion 4 is set to be larger than the inner diameter of the mounting hole 2 and smaller than the outer diameter of the upper end of the cylindrical body 1.

-Small diameter portion An annular outward projection 51 is integrally formed on the outer peripheral surface of the lower end portion of the small diameter portion 5. The outward projection 51 has a guide portion 51a formed of an inclined surface (that is, a conical surface) whose outer diameter gradually increases toward the upper side. The outward projection 51 has an upper end surface that is a surface perpendicular to the axis. An acute corner is formed between the guide 51a and the upper end surface. The corner portion becomes the maximum outer diameter portion 51 b of the outward projection 51. That is, the outward projection 51 includes a guide portion 51a formed of an inclined surface whose outer diameter gradually increases as it goes upward, and a maximum outer diameter portion 51b formed above the guide portion 51a.

The maximum outer diameter of the outward projection 51 (that is, the outer diameter of the maximum outer diameter portion 51 b) is larger than the minimum inner diameter of the inward projection 21 (that is, the inner diameter of the minimum inner diameter portion 21 b) and above the inward projection 21. It is set smaller than the inner diameter b. In the present embodiment, the maximum outer diameter of the outward projection 51 is set to 4.9 mm, and the minimum inner diameter of the inward projection 21 is set to 4.1 mm. The difference between the maximum outer diameter of the outward projection 51 and the minimum inner diameter of the inward projection 21 is preferably in the range of 0.5 mm to 2 mm (preferably 0.5 mm to 1 mm). Thereby, the soft member 3 can be reliably prevented from falling off, and the outward projection 51 and the inward projection 21 can be smoothly climbed over.

An inner hole 31 extending in the axial direction is formed in the soft member 3. The lower end of the inner hole 31 is opened downward in the axial direction. The upper end of the inner hole 31 is located inside the large diameter portion 4. Due to the inner hole 31, the soft member 3 is formed in a bottomed cylindrical shape with the upper end closed and the lower end opened. In the present embodiment, since the inner hole 31 is formed at least radially inward of the outward projection 51, the outward projection 51 is elastic inward in the radial direction when the outward projection 51 gets over the inward projection 21. Deformation is easy.

Further, the outer peripheral surface of the front end portion of the small diameter portion 5 (that is, the outer peripheral surface of the connecting portion of the small diameter portion 5 and the shoulder portion 41 of the large diameter portion 4) has an inclined surface shape in which the outer diameter gradually increases toward the upper side. A base 52 having a conical shape is formed. When the soft member 3 is inserted into the mounting hole 2, the inclined base 52 is brought into pressure contact with the opening edge of the mounting hole 2 and the wobbling of the soft member 3 in the radial direction is suppressed.

The outer diameter a of the intermediate portion of the small-diameter portion 5 (that is, the portion between the outward projection 51 and the inclined base 52) is larger than the inner diameter b of the mounting hole 2 above the inward projection 21. Set small. Thereby, when the outward protrusion 51 and the inward protrusion 21 immediately before the outward protrusion 51 gets over the inward protrusion 21 abuts, the outer peripheral surface of the small-diameter portion 5 above the outward protrusion 51 and the upward protrusion 21 above. An annular space 6 is formed between the inner peripheral surface of the mounting hole 2. As shown in FIG. 5, when the outward projection 51 and the inward projection 21 are strongly pressed immediately before the outward projection 51 gets over the inward projection 21, the small-diameter portion 5 above the outward projection 51 is radially outward. Even if it swells due to elastic deformation, since the annular space 6 is formed, the outer peripheral surface of the small-diameter portion 5 above the outward projection 51 is not strongly pressed against the inner peripheral surface of the mounting hole 2, and the soft member 3 is inserted. There is no risk of time resistance. As a result, it is possible to smoothly get over the outward projection 51 and the inward projection 21. Specifically, the outer diameter a is set to 4.9 mm, and the inner diameter b is set to 5.6 mm.

Axial gap A The length A in the axial direction from the shoulder 41 of the soft member 3 to the upper end of the outward projection 51 (that is, the maximum outer diameter portion 51b) is from the upper end of the cylindrical body 1 to the inward projection 21 of the mounting hole 2. It is set slightly larger than the length B in the axial direction to the lower end (that is, the minimum inner diameter portion 21b) (see FIG. 4). Thereby, when the outward projection 51 gets over the inward projection 21, the outward projection 51 can surely get over the inward projection 21 even if the outward projection 51 and the inward projection 21 slip poorly. As shown in FIG. 6, the upper end of the outward projection 51 (ie, the maximum outer diameter portion 51b) is the lower end of the inward projection 21 (ie, the minimum inner diameter portion 21b) after the insertion of the soft member 3 into the mounting hole 2 is completed. A gap C in the axial direction is formed between the lower end of the inward projection 21 and the upper end of the outward projection 51. Specifically, the axial gap C is effectively in the range of 0.05 mm to 1.0 mm (preferably 0.1 mm to 0.5 mm). Due to the size of the gap C in the axial direction, there is no large backlash in the axial direction even when the soft member 3 is used, and the inward projection 21 and the outward projection 51 can be reliably overcome when the soft member 3 is inserted. . 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.

-Insertion of a soft member The insertion process of the soft member 3 of this Embodiment is demonstrated according to drawing.
As shown in FIG. 4, the lower end of the small diameter portion 5 of the soft member 3 is inserted into the upper end opening of the mounting hole 2 of the cylindrical body 1.

Further, when the small diameter portion 5 is inserted into the mounting hole 2, the guide portion 51 a of the outward projection 51 of the small diameter portion 5 of the soft member 3 comes into contact with the guide portion 21 a of the inward projection 21 of the mounting hole 2. As shown in FIG. 5, immediately before the outward projection 51 gets over the inward projection 21, the outer peripheral surface of the small diameter portion 5 is bulged and deformed outward in the radial direction. At this time, since the annular space 6 exists between the inner peripheral surface of the mounting hole 2 and the outer peripheral surface of the small diameter portion 5, the outer peripheral surface of the small diameter portion 5 that has bulged and deformed is not strongly pressed against the inner peripheral surface of the mounting hole 2. Thereby, the insertion of the soft member 3 is not hindered, and the outer protrusion 51 and the inward protrusion 21 can smoothly get over. Further, immediately before the outward protrusion 51 gets over the inward protrusion 21, the minimum inner diameter portion 21 b of the inward protrusion 21 protruding downward by the concave portion 25 is elastically deformed radially outward, and the outward protrusion 51 and the inward protrusion 21 are smoothly formed. Overcoming is possible.

As shown in FIG. 6, an axial gap C is formed between the upper end of the outward projection 51 and the lower end of the inward projection 21 in the state where the outward projection 51 and the inward projection 21 have been overcome. . As a result, even if the sliding between the outward projection 51 and the inward projection 21 is poor, the outward projection 51 and the inward projection 21 can be reliably overcome without applying a lubricant or the like. In addition, in the state in which the outward projection 51 and the inward projection 21 have been overcome, the inward projection 21 is pressed against the outer peripheral surface of the small-diameter portion 5 above the outward projection 51. Thereby, backlash of the small diameter part 5 in the axial direction and the radial direction can be prevented. In addition, the upper end of the cylindrical body 1 is in pressure contact with the shoulder 41 and the base 52 in a state where the outward projection 51 and the inward projection 21 have been overcome. Thereby, the immersion of the large diameter portion 4 into the mounting hole 2 can be prevented, and the radial play of the large diameter portion 4 can be prevented.

It is a principal part longitudinal cross-sectional view which shows the state before inserting the soft member of the 1st Embodiment of this invention in the attachment hole of a cylinder. FIG. 2 is a longitudinal sectional view of an essential part showing a state immediately before an outward projection of the soft member of FIG. 1 gets over an inward projection of an attachment hole. It is a principal part longitudinal cross-sectional view which shows the state after inserting the soft member of FIG. 1 in the attachment hole of a cylinder. It is a principal part longitudinal cross-sectional view which shows the state before inserting the soft member of the 2nd Embodiment of this invention in the attachment hole of a cylinder. FIG. 5 is a longitudinal sectional view of an essential part showing a state immediately before an outward projection of the soft member of FIG. 4 gets over an inward projection of an attachment hole. It is a principal part longitudinal cross-sectional view which shows the state after inserting the soft member of FIG. 4 in the attachment hole of a cylinder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical body 2 Mounting hole 21 Inward protrusion 21a Guide part 21b Minimum inner diameter part 22 Rib 23 Recessed part 3 Soft member 31 Inner hole 4 Large diameter part 41 Shoulder part 5 Small diameter part 51 Outward protrusion 51a Guide part 51b Maximum outer diameter part 52 Base 6 Annular space
A Length in the axial direction from the lower end of the large diameter portion to the upper end of the outward projection B Length in the axial direction from the upper end of the cylindrical body to the lower end of the inward projection C Axial clearance a Outer diameter b of the intermediate portion of the small diameter portion Inner diameter of the hole above the inward projection of the hole

Claims (8)

A mounting structure for a soft member, which is provided with a mounting hole that opens upward in the axial direction at the upper end portion of a cylindrical body such as a shaft cylinder or a cap of a writing instrument, and a soft member is inserted into the mounting hole. A soft member mounting structure, wherein an inward projection is formed on an inner peripheral surface, an outward projection is formed on an outer peripheral surface of the soft member, and the outward projection passes over the inward projection from above. 2. The soft member mounting structure according to claim 1, wherein when the soft member is inserted into the mounting hole, an annular space is provided between the inner peripheral surface of the upper portion of the mounting hole and the outer peripheral surface of the soft member. The soft member is composed of a large-diameter portion that protrudes upward in the axial direction from the upper end of the cylindrical body, and a small-diameter portion that is integrally connected downward from the large-diameter portion and is inserted into the mounting hole. 3. The mounting hole opening end and the large-diameter portion lower end are contacted in the axial direction in a state of being inserted into the hole, and an axial gap is provided between the inward projection and the outward projection. Mounting structure for soft members. The soft member mounting structure according to any one of claims 1 to 3, wherein an inner hole in the axial direction is formed inside the soft member, and at least the inner hole is located radially inward of the outward projection. The soft member mounting structure according to any one of claims 1 to 4, wherein the inward projection is in pressure contact with the outer peripheral surface of the soft member in a state where the soft member is inserted into the mounting hole. The soft member mounting structure according to claim 1, wherein the inward projection is annular and the outward projection is annular. The inward projection includes a guide portion having an inclined surface whose inner diameter decreases as it goes downward, and a minimum inner diameter portion formed below the guide portion, and the minimum inner diameter portion is located at a lower end of the inward projection. Item 7. The soft member mounting structure according to any one of Items 1 to 6. The cylindrical body and the inward projection are integrally formed by molding a synthetic resin, and a recess opening downward is formed between the minimum inner diameter portion of the inward projection and the inner surface of the mounting hole, and the minimum inner diameter portion protrudes downward. The flexible member mounting structure according to claim 7.

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