JP2021133673A - Mounting structure of soft member - Google Patents

Abstract

To provide a mounting structure of a soft member capable of preventing a middle core from being exposed to damage a paper sheet surface even when the soft material is worn, and allowing the soft member to be easily mounted.SOLUTION: The mounting structure of a soft member is provided with a mounting hole open upward in an axial direction in an upper end part of a cylindrical body. An inward facing protrusion is formed on an inner peripheral surface of the mounting hole, an outward facing protrusion is formed on an outer peripheral surface of the soft member, and the outward facing protrusion and the inward facing protrusion are vertically engaged with each other so as not to be slipped off from each other. The soft member is provided with an axially open inner hole, and a middle core is fixedly inserted into the inner hole. The middle core is in a non-contact state with the cylindrical body. The middle core is positioned at least on a radially inner side of the outward facing protrusion. An outer peripheral surface of the middle core is in press-contact with an inner peripheral surface of the inner hole. An upper end part of the middle core is positioned at the same position as the upper end part of the cylindrical body or below the upper end part of the cylindrical body.SELECTED DRAWING: Figure 4

Description

The present invention relates to a mounting structure for a soft member. More specifically, the present invention relates to a mounting structure for a soft member in which a mounting hole that opens upward in the axial direction is provided at the upper end of a cylinder such as a shaft cylinder or a cap of a writing instrument, and the soft member is inserted into the mounting hole.

Conventionally, Patent Document 1 comprises a main body, an operation portion rotatably provided at an end portion of the main body, and an elastic material provided at the end portion of the operation portion for the purpose of obtaining friction portions having various hardnesses. A friction tool including a friction portion and a movable body housed inside the operation portion and movable in the front-rear direction by rotation of the operation portion, and configured so that the movable body can be pressed against the inside of the friction portion. It is disclosed.

Further, Patent Document 2 has a fitting portion whose end portion is arranged on the central axis and a connection portion connecting the end portion and the fitting portion for the purpose of easily attaching the erasing member. However, the writing tool disclosed that the erasing member has a fitting hole for receiving the fitting portion and the connecting portion, and a gap space is formed around the connecting portion in a state where the erasing member is attached. Has been done.

JP 2012-232484 JP 2013-139135

In Patent Document 1, the friction portion can be used in a state where the end portion of the core portion of the movable body is pressed against the inside of the friction portion. As a result, as shown in FIG. 2 of Patent Document 1, there is a core portion immediately behind the convex curved end portion, and the core portion is exposed when the friction portion is gradually worn during long-term use. There is a risk of coming.

If the paper surface is continuously rubbed with the friction portion while the core portion is exposed, the exposed core portion may damage the paper surface.

In particular, when the friction part is made of a highly wear-resistant soft member (for example, an eraser), wear of the friction part due to friction is unavoidable, and the movable body is easily exposed during use, which may damage the paper surface. be.

On the other hand, in Patent Document 2, since the front end of the fitting portion has substantially the same height as the front end surface, the core portion (fitting portion) is exposed even if the friction portion gradually wears during long-term use. There is no.

However, in order to achieve the state shown in FIG. 14 of the patent document (that is, the erasing member is attached to the cap), the small diameter portion on the inner surface of the erasing member is radially outward on the fitting portion. The process of elastically deforming and moving in the axial direction and the process of moving the engaging protrusion 2d on the outer surface of the erasing member in the axial direction while elastically deforming inward on the inner peripheral surface of the support wall. Must be done at the same time.

Therefore, the vicinity of the engaging protrusion of the erasing member is elastically deformed from both the inner and outer sides in the radial direction at the same time, and a large pressure input is required to attach the erasing member to the cap. As a result, it may be difficult to easily attach the erasing member.

The present invention solves the above-mentioned conventional problems, and even if the soft member is worn, the core is not exposed and the paper surface is not damaged, and the soft member can be easily attached. It seeks to provide a structure.

In the present invention, in the tubular body, "upper" refers to the mounting hole side, and "lower" refers to the opposite side. Further, in the present invention, in the soft member, "lower" refers to the insertion side into the mounting hole, and "upper" refers to the opposite side.

The present invention is a structure for attaching a soft member to the upper end of a barrel of a writing instrument or a cylinder of a cap.
A mounting hole that opens upward in the axial direction is provided at the upper end of the cylinder, an inward protrusion is formed on the inner peripheral surface of the mounting hole, and an outward protrusion is formed on the outer peripheral surface of the soft member. The inward projection is locked in the vertical direction to prevent it from coming off, the soft member is provided with an inner hole that opens in the axial direction, a core is inserted into the inner hole, and the core is in a non-contact state with the cylinder. The core is located at least inward in the radial direction of the outward protrusion, the outer peripheral surface of the core is pressed against the inner peripheral surface of the inner hole, and the upper end of the core is of the cylinder. The soft member mounting structure according to claim 1, which is located at the same position as the upper end portion or below the upper end portion of the cylinder.

According to the present invention, the outer peripheral surface of the core is pressed against the inner peripheral surface of the inner hole, and the upper end of the core is at the same position as the upper end of the cylinder or below the upper end of the cylinder. Since the soft member is located at, the core is not exposed and the paper surface is not damaged even if the soft member is worn, and the soft member can be easily attached.

Further, it is preferable that the inner hole opens downward in the axial direction, the soft member is a bottomed tubular body, and the core is provided with a ventilation portion penetrating in the axial direction.

According to this, the air in the inner hole of the soft member is not compressed, and the core can be easily attached to the soft member, and the soft member and the core can be securely attached.

The core preferably has a symmetrical shape in the vertical direction.

This eliminates the need to select the direction of the core when inserting the core into the inner hole, and improves the assemblability (insertability) when the core is inserted into the inner hole.

The ventilation portion is preferably a through hole that penetrates the inside of the core in the axial direction.

As a result, the air in the inner hole of the soft member is not compressed and is surely discharged to the outside through the through hole, so that the core can be easily attached to the inner hole of the soft member.

The ventilation portion is preferably a groove or a protrusion provided on the outer peripheral surface of the core and penetrating in the axial direction.

According to this, since the ventilation portion is provided on the outer peripheral surface of the core and is a groove or a protrusion penetrating in the axial direction, the air in the inner hole of the soft member is not compressed and is surely passed through the through hole. Since it is discharged to the outside, the core can be easily attached to the inner hole of the soft member. Further, since the groove or protrusion penetrates in the axial direction, when the core is inserted into the inner hole of the soft member, the resistance at the time of insertion is reduced and the core can be attached more easily.

The outer peripheral surface of the soft member is composed of a large-diameter portion, a small-diameter portion integrally connected below the large-diameter portion, and a shoulder portion formed between the large-diameter portion and the small-diameter portion. The outward protrusions are preferably formed on the outer peripheral surface of the small diameter portion.

According to this, a desired frictional performance can be obtained by the large diameter portion of the soft member, and the soft member can be reliably attached to the cylinder by the shoulder portion and the outward protrusion of the soft member.

It is preferable that the lower end portion of the core does not protrude downward from the lower end portion of the soft member at the same position in the vertical direction as the lower end portion of the soft member.

According to this, the core can be easily inserted into the soft member, and the assembling property is improved.

It is preferable to provide a protrusion on the outer peripheral surface of the core.

According to this, the core can be held more firmly in the inner hole, and the core can be reliably prevented from falling out of the inner hole.

In the mounting structure of the soft member of the present invention, even if the soft member is worn, the core is not exposed and the paper surface is not damaged, and the soft member can be easily mounted.

It is a vertical cross-sectional view of a main part which shows the state before inserting the soft member of embodiment of this invention into a mounting hole of a cylinder body. FIG. 3 is a vertical cross-sectional view of a main part showing a temporarily inserted state of the soft member of FIG. 1 into a mounting hole. FIG. 3 is a vertical cross-sectional view of a main part showing a state after the soft member of FIG. 1 is inserted into a mounting hole of a tubular body. FIG. 3 is a vertical cross-sectional view of a main part showing a state after the core is inserted into the inner hole of the soft member of FIG. 1.

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

1 to 4 show embodiments of the present invention. The mounting structure of the soft member 3 of the present embodiment includes a tubular body 1 having a mounting hole 2 at the upper end, a soft member 3 inserted into the mounting hole 2 of the tubular body 1, and a shaft of the soft member 3. It is composed of a core 7 inserted into an inner hole 31 provided in the core.

-Cylindrical body The tubular body 1 is obtained by injection molding of a synthetic resin (for example, polypropylene). Examples of the cylinder 1 include a shaft cylinder of a writing instrument or a removable cap on the pen tip side of the shaft cylinder. A mounting hole 2 that opens upward in the axial direction is formed at the upper end of the tubular body 1. The mounting hole 2 is formed on the closed end side of the cap when the cylinder 1 is a cap, and the end opposite to the pen tip (tail end of the shaft cylinder) when the cylinder 1 is a shaft cylinder. Is formed in. The mounting hole 2 has a circular cross section.

An annular inward projection 21 is integrally formed on the inner peripheral surface of the inward projection 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 toward the bottom. Further, a minimum inner diameter portion 21b is formed at the lower end of the inward projection 21 below the guide portion 21a.

-Soft member The soft member 3 is composed of a large-diameter portion 4 and a small-diameter portion 5 integrally connected below the large-diameter portion 4, and is integrally formed of an elastic material. The elastic material constituting the soft member 3 is preferably a synthetic resin (rubber, elastomer) having elasticity, for example, a silicone resin, an SBS resin (styrene-butadiene-styrene copolymer), and a SEBS resin (styrene-ethylene-butylene-). Styrene copolymer), fluororesin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM) and the like. The elastic synthetic resin constituting the soft member 3 is preferably made of a low-wear elastic material in which almost no wear residue (erasing residue) is generated during friction. In addition, the elastic material constituting the soft member 3 may be a highly wear-resistant elastic material such as an eraser, an input member of an input pen used for a personal digital assistant, or the like.

-Large-diameter portion The large-diameter portion 4 projects upward from the upper end of the tubular body 1. At the lower end of the large diameter portion 4, a shoulder portion 41 that can come into contact with the open end of the mounting hole 2 (that is, the upper end of the tubular body 1) is formed. 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 tubular body 1. The outer peripheral surface of the large diameter portion 4 of the soft member 3 serves as a friction portion 32 and is a contact surface that can come into contact with a contact surface such as a paper surface. The wall thickness of the friction portion 32 is preferably the thickest at the top. As a result, the rigidity of the top and its vicinity, which is the part used most during friction, is increased, and the heat-discolorable image or handwriting can be appropriately heat-discolored.

-Small diameter portion An annular outward protrusion 51 is integrally formed on the outer peripheral surface of the lower end portion of the small diameter portion 5. The outward protrusion 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 protrusion 51 has an upper end surface formed of a surface perpendicular to the axis. The area between the guide portion 51a and the upper end surface of the outward protrusion 51 is the maximum outer diameter portion 51b of the outward protrusion 51. That is, the outward protrusion 51 includes a guide portion 51a formed of an inclined surface whose outer diameter gradually increases toward the upper side, and a maximum outer diameter portion 51b formed above the guide portion 51a.

The maximum outer diameter of the outward protrusion 51 (that is, the outer diameter of the maximum outer diameter portion 51b) is larger than the minimum inner diameter of the inward protrusion 21 (that is, the inner diameter of the minimum inner diameter portion 21b) and the inner diameter of the mounting hole 2 above the inward protrusion 21. Set smaller. In the present embodiment, the difference between the maximum outer diameter of the outward protrusion 51 and the minimum inner diameter of the inward protrusion 21 is set in the range of 0.5 mm to 2 mm (preferably 0.5 mm to 1 mm). As a result, the soft member 3 can be reliably prevented from falling off, and the outward protrusion 51 and the inward protrusion 21 are smoothly locked in the vertical direction.

-Inner hole An inner hole 31 extending in the axial direction is formed inside the soft member 3. At least, the lower end of the inner hole 31 is opened downward in the axial direction. In the present embodiment, since the inner hole 31 is formed at least inward in the radial direction of the outward protrusion 51, the outward protrusion 51 and the inward protrusion 21 are outwardly oriented when they are locked in the vertical direction. Elastic deformation of the protrusion 51 inward in the radial direction becomes easy. As will be described later, when the soft member 3 is inserted into the mounting hole 2 of the tubular body 1, since the core 7 is not inserted into the inner hole 31, the outward protrusion 51 is elastically deformed inward in the radial direction. Is possible.

A bulging portion 52 is formed on the outer peripheral surface of the upper end portion of the small diameter portion 5 (that is, the outer peripheral surface of the continuous portion of the small diameter portion 5 and the shoulder portion 41 of the large diameter portion 4). When the soft member 3 is inserted into the mounting hole 2, the bulging portion 52 is brought into contact with the inner peripheral surface of the opening end portion of the mounting hole 2, and the radial wobbling of the soft member 3 is suppressed. The outer diameter of the bulging portion 52 is set to be substantially equal to the inner diameter of the open end portion of the mounting hole 2. Further, the outer diameter of the bulging portion 52 is set to be smaller than the maximum outer diameter of the large diameter portion 4 and larger than the maximum outer diameter of the outward protrusion 51.

Lower extension portion A lower extension portion 53 having an outer diameter smaller than the minimum inner diameter of the inward protrusion 21 is formed below the outward protrusion 51 of the soft member 3. The lower extension portion 53 is continuously provided at the lower end of the guide portion 51a of the outward protrusion 51. In the present embodiment, the outer peripheral surface of the lower extension portion 53 is a straight circumferential surface. In addition to this, the outer peripheral surface of the lower extension portion 53 may be composed of an inclined surface (conical surface) whose outer diameter increases toward the lower side. In particular, when the soft member 3 is temporarily inserted in the mounting hole 2, the inward projection 21 and the downward extension portion 53 are not fitted, so that the soft member 3 is dropped below the mounting hole 2. It is possible to make a temporary insertion state only by itself, and the attachment process of the soft member 3 can be simplified.

The outer diameter of the intermediate portion (that is, the portion between the outward protrusion 51 and the bulging portion 52) of the annular space small diameter portion 5 is set to be smaller than the inner diameter of the portion above the inward protrusion 21 of the mounting hole 2. As a result, when the outward protrusion 51 and the inward protrusion 21 come into contact with each other (that is, at the time of temporary insertion) immediately before the outward protrusion 51 and the inward protrusion 21 are locked in the vertical direction, they are above the outward protrusion 51. An annular space 6 is formed between the outer peripheral surface of the small diameter portion 5 and the inner peripheral surface of the mounting hole 2 above the inward projection 21. Immediately before the outward protrusion 51 and the inward protrusion 21 are locked in the vertical direction to prevent them from coming off, when the outward protrusion 51 and the inward protrusion 21 are strongly pressed against each other, the small diameter portion 5 above the outward protrusion 51 is in the radial direction. Even if it swells outward due to elastic deformation, since the annular space 6 is formed, the outer peripheral surface of the small diameter portion 5 above the outward protrusion 51 is not strongly pressed against the inner peripheral surface of the mounting hole 2, and the soft member 3 There is no risk of resistance during insertion. As a result, the outward protrusion 51 and the inward protrusion 21 can be smoothly locked in the vertical direction to prevent them from coming off.

Axial gap The axial length A from the shoulder portion 41 of the soft member 3 to the upper end of the outward protrusion 51 (that is, the maximum outer diameter portion 51b) is the inward protrusion 21 of the mounting hole 2 from the upper end of the tubular body 1. It is set slightly larger than the axial length B to the lower end (that is, the minimum inner diameter portion 21b). As a result, when the outward protrusion 51 and the inward protrusion 21 are locked in the vertical direction to prevent them from coming off, even if the outward protrusion 51 and the inward protrusion 21 are not slippery, the outward protrusion 51 and the inward protrusion 21 are surely kept in contact with each other. It can be locked in the vertical direction. As shown in FIG. 3, in a state where the soft member 3 has been inserted into the mounting hole 2, the upper end of the outward protrusion 51 (that is, the maximum outer diameter portion 51b) is the lower end of the inward protrusion 21 (that is, the minimum inner diameter portion 21b). 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. The axial gap C is specifically set 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 clearance C in the axial direction, there is no large rattling in the axial direction even when the soft member 3 is used, and moreover, the outward protrusion 51 and the inward protrusion 21 are surely prevented from coming off in the vertical direction when the soft member 3 is inserted. A locked state is obtained.

-Insertation of soft member The insertion process of the soft member 3 of the present embodiment will be described with reference to the drawings.

As shown in FIG. 1, the small diameter portion 5 of the soft member 3 is inserted into the upper end opening of the mounting hole 2 of the tubular body 1 from above the mounting hole 2 of the tubular body 1.

After that, as shown in FIG. 2, the outward protrusion 51 of the small diameter portion 5 of the soft member 3 (that is, the guide portion 51a of the outward protrusion 51) becomes the inward protrusion 21 of the mounting hole 2 (that is, the guide portion 21a of the inward protrusion 21). It is in a state of contact (that is, a temporary insertion state). Further, in this temporary insertion state, the soft member 3 may be in a state of being tilted with respect to the axis of the tubular body 1 (not shown). In the temporary insertion state (FIG. 2), the lower extension portion 53 of the soft member 3 is inserted into the minimum inner diameter portion 21b of the inward projection 21 in a non-fitting state. That is, in the temporarily inserted state, the lower extension portion 53 of the soft member 3 is located within the minimum inner diameter portion 21b of the inward projection 21 or below the minimum inner diameter portion 21b. In particular, when the soft member 3 is tilted with respect to the axis of the tubular body 1, the outer peripheral surface of the lower extension portion 53 and the inner peripheral surface of the minimum inner diameter portion 21b of the outward protrusion 51 are locked, and the soft member 3 Can be reliably prevented from falling out of the mounting hole 2.

Further, when the soft member 3 is inserted into the mounting hole 2, the outer peripheral surface of the small diameter portion 5 is radially outward just before the outward protrusion 51 and the inward protrusion 21 are locked in the vertical direction. It bulges and deforms. In the temporary insertion state, 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 bulging and deformed outer peripheral surface of the small diameter portion 5 is not strongly pressed against the inner peripheral surface of the mounting hole 2. As a result, the outward protrusion 51 and the inward protrusion 21 can be smoothly locked in the vertical direction so as not to interfere with the insertion of the soft member 3.

Then, as shown in FIG. 3, in a state where the outward protrusion 51 and the inward protrusion 21 are locked in the vertical direction to prevent them from coming off, there is an axial gap between the upper end of the outward protrusion 51 and the lower end of the inward protrusion 21. C is formed. As a result, even if the outward protrusion 51 and the inward protrusion 21 are not slippery, the outward protrusion 51 and the inward protrusion 21 can be securely locked in the vertical direction without applying a lubricant or the like. Further, in a state where the outward protrusion 51 and the inward protrusion 21 are locked in the vertical direction to prevent them from coming off, the inward protrusion 21 is pressed against the outer peripheral surface of the small diameter portion 5 above the outward protrusion 51. Thereby, rattling in the axial direction and the radial direction of the small diameter portion 5 can be prevented. Further, in a state where the outward protrusion 51 and the inward protrusion 21 are locked in the vertical direction to prevent them from coming off, the upper end of the tubular body 1 is pressed against the shoulder portion 41 of the large diameter portion 4, and the bulging portion 52 is attached to the mounting hole 2. Is in contact with the inner peripheral surface of the open end of the. As a result, it is possible to prevent the large diameter portion 4 from getting into the mounting hole 2, and it is possible to prevent the large diameter portion 4 from rattling in the radial direction.

-Core core In the present embodiment, the core core 7 is located at least inward in the radial direction of the outward protrusion 51 in a state of being mounted on the inner hole 31, and the outer peripheral surface of the core 7 is the inner peripheral surface of the inner hole 31. Is in pressure contact with. As a result, the soft member 3 is firmly fixed to the tubular body, the friction portion 32 having a desired rigidity can be obtained in the entire friction portion 32, and the image or handwriting of thermal discoloration can be appropriately thermally discolored. .. In particular, even when the friction portion 32 is made of a material having a low hardness, the friction portion 32 having a desired rigidity can be obtained in the entire friction portion 32, and the image or handwriting of thermal discoloration is appropriately thermally discolored. be able to.

Here, the rigidity of the friction portion 32 represents deformation resistance to an external force (force applied to the soft member 3 during a friction operation) on the soft member 3, and is also referred to as stiffness. Specifically, there are tensile rigidity, compressive rigidity, flexural rigidity, shear rigidity, torsional rigidity, and the like corresponding to various deformations of the soft member 3. Here, the desired rigidity varies greatly depending on the design conditions and the image of thermal discoloration of the friction target or the handwriting. For example, when the soft member 3 is bent or sheared, the soft member 3 is less likely to buckle. Represents. If the desired rigidity is not obtained, the soft member 3 may buckle and undergo plastic deformation, breakage or damage. In addition, it may not be possible to generate the desired frictional heat, and the heat-discolorable image or handwriting may not be properly heat-discolored.

The outer peripheral surface of the core 7 and the inner peripheral surface of the inner hole 31 are in pressure contact with each other when the inner diameter of the inner hole 31 and the outer diameter of the core 7 are substantially the same, or the inner diameter of the inner hole 31 is larger than the inner diameter of the inner hole 31. The outer diameter of the core 7 is clearly large, and the core 7 is press-fitted into the inner hole 31. As a result, there is no possibility that the core 7 will come out of the inner hole 31.

Further, since the outer peripheral surface of the core 7 is in contact with the inner peripheral surface of the inner hole 31, the rigidity of the outward protrusion 51 located on the outer side in the radial direction of the core 7 is increased, and the rigidity of the outer protrusion 51 is increased, and the inner side of the outer protrusion 51 is increased. Even if the elasticity of the soft member 3 decreases due to aging or the like, the soft member 3 can be reliably prevented from falling off due to the strong engagement between the outward protrusion 51 and the inward protrusion 21. Therefore, there is no possibility that the soft member 3 will fall out from the mounting hole 2.

When rubbing a heat-discolorable image or handwriting, it is necessary to have a desired frictional performance in the entire friction portion 32. For example, when the top portion (upper end portion) of the friction portion 32 has a hole or the like, the handwriting cannot be efficiently rubbed at the top portion of the friction portion 32, and there is a possibility that the handwriting cannot be appropriately discolored by heat. In the present embodiment, the soft member 3 is a bottomed tubular body provided with an inner hole 31 that opens downward in the axial direction.

The material constituting the core 7 may be, for example, a synthetic resin material, and the synthetic resin material may be, for example, polypropylene, polyethylene, polystyrene, polycarbonate, polyethylene terephthalate, polyacetal, acrylic, nylon, acrylonitrile / styrene copolymer. Examples thereof include synthetic resins that are harder than the soft member 3 such as resin (AS resin) and acrylonitrile / butadiene / styrene copolymer resin (ABS resin). Further, it may be made of rubber or elastomer that is harder than the soft member 3, and may be, for example, a silicone resin, an SBS resin (styrene-butadiene-styrene copolymer), or a SEBS resin (styrene-ethylene-butylene-styrene copolymer). ), Fluorine resin, chloroprene resin, nitrile resin, polyester resin, ethylene propylene diene rubber (EPDM) are exemplified. Further, if it is a metal, aluminum alloy, stainless steel, brass and the like can be mentioned. The core 7 is obtained by cutting or plastic working when the material is metal, and is obtained by cutting or injection molding when the material is synthetic resin.

As shown in FIG. 4, the core 7 preferably has a symmetrical shape in the vertical direction. This eliminates the need to select the direction of the core 7 when inserting the core 7 into the inner hole 31. Further, it is preferable that at least one end is chamfered or R-chamfered. As a result, the assemblability (insertability) when the core 7 is inserted into the inner hole 31 is further improved.

-Insert core 7 As shown in FIG. 3, the core 7 is inside the soft member 3 as shown in FIG. 4 after the soft member 3 and the cylinder 1 are locked in the vertical direction to prevent them from coming off. It is inserted into the hole 31. Since the soft member 3 to which the core 7 is not mounted has flexibility in the small diameter portion 5 (outer diameter protrusion), it can be easily mounted in the mounting hole 2 of the tubular body 1. On the other hand, when the soft member 3 to which the core 7 is inserted is inserted into the mounting hole 2 of the tubular body 1, the flexibility of the small diameter portion 5 (outer diameter protrusion) is reduced, and the soft member 3 is easily attached to the tubular body. There is a possibility that it cannot be inserted into 1 and 2.

In the present embodiment, the core 7 is in a non-contact state with the cylinder 1. In other words, the core 7 is separate from the tubular body 1. As a result, as shown in FIG. 3, the core 7 is formed in the inner hole 31 of the soft member 3 as shown in FIG. 4 after the soft member 3 and the tubular body 1 are locked in the vertical direction to prevent them from coming off. Assembling can be performed in the above-mentioned two steps of inserting and removing.

According to the method for attaching the soft member described above, the vicinity of the outward protrusion 51 of the soft member 3 is not elastically deformed from both the inward and outward sides in the radial direction at the same time. The soft member 3 can be easily attached without requiring a large pressure input for attaching.

The soft member 3 may be a bottomed tubular body 1 having an inner hole 31 that opens downward in the axial direction. Along with this, it is preferable that the core 7 is provided with a ventilation portion 71 penetrating in the axial direction. In the present embodiment, the ventilation portion 71 is a through hole having a circular cross section that penetrates the axial center of the core 7. The form of the ventilation portion 71 is not limited to the through hole having a circular cross section penetrating the axial center, and may be a through hole penetrating a portion other than the axial center. Further, it may be at least one groove extending in the axial direction on the outer peripheral surface of the core 7. Further, it may be a spiral groove extending spirally on the outer peripheral surface of the core 7. In particular, when the ventilation portion 71 is a spiral groove, the effect of preventing the core 7 from coming off from the soft member 3 is also obtained.

Further, according to this, since the soft member 3 is a bottomed tubular body 1 having an inner hole 31 that opens downward in the axial direction, the rigidity of the soft member 3 is further improved, so that the soft member 3 is bent at the time of assembly. Prevents too much assembly failure. That is, the assemblability of the soft member 3 to the shaft cylinder is improved.

Further, since the core 7 is provided with a ventilation portion 71 penetrating in the axial direction, when the core 7 is inserted into the inner hole 31 of the bottomed soft member 3, the air in the inner hole 31 is appropriately removed. The air inside the inner hole 31 can be surely released to the outside without being compressed, and the core 7 can be easily inserted into the inner hole 31. That is, the assemblability of the core 7 to the soft member 3 is improved.

In the present embodiment, the ventilation portion 71 is a through hole that penetrates inside the core in the axial direction. As a result, the air in the inner hole of the soft member is not compressed and is surely discharged to the outside through the through hole, so that the core can be easily attached to the inner hole of the soft member.

Further, the ventilation portion 71 may be a groove or a protrusion provided on the outer peripheral surface of the core 7 and penetrating in the axial direction. As a result, the air in the inner hole 31 of the soft member 3 is not compressed and is surely discharged to the outside through the through hole, so that the core 7 can be easily attached to the inner hole 31 of the soft member 3. Further, since the groove or protrusion penetrates in the axial direction, when the core 7 is inserted into the inner hole 31 of the soft member 3, the resistance at the time of insertion is reduced and the core 7 can be attached more easily. .. That is, the assemblability of the core 7 to the soft member 3 is improved.

Further, instead of providing the ventilation portion 71, an inner groove or an inner protrusion that penetrates in the axial direction may be provided on the inner surface of the inner hole 31, and the air is not compressed and the inner groove or the inner protrusion is provided as in the above ventilation portion. Since the core 7 is surely discharged to the outside through the soft member 3, the core 7 can be easily attached to the inner hole 31 of the soft member 3.

The outer diameter of the core 7 of the present embodiment is the same except for the draft required for molding, but the lower core 73 may be thicker than the upper core 72. This makes it easy to insert the core 7 into the inner hole 31. Further, even when an external force is applied in the direction in which the soft member 3 comes out of the tubular body 1, the rigidity of the outward protrusion 51 is further increased, and the inward deformation of the outward protrusion 51 can be further suppressed. The strong engagement between the 51 and the inward projection 21 makes it possible to reliably prevent the soft member 3 from falling off, and there is no possibility that the soft member 3 will fall off from the mounting hole 2.

As a method of holding (fixing) the core 7, for example, the core 7 may be held by roughening the surface roughness of the outer peripheral surface of the core 7, or the core 7 may be held outside the inner diameter of the inner hole 31. The diameter may be obviously increased and the core 7 may be held by strongly press-fitting into the inner hole 31. Alternatively, a protrusion or a burred protrusion may be provided on the portion of the core 7 that contacts the inner peripheral surface of the inner hole 31 to prevent it from coming off. As a result, the core 7 can be held more firmly in the inner hole 31 and the core 7 can be reliably prevented from falling out of the inner hole 31.

It is preferable that the lower end portion of the core 7 does not protrude downward from the lower end portion of the soft member 3 at the same position in the vertical direction as the lower end portion of the soft member 3. According to this, the core 7 can be easily inserted into the soft member 3, and the assembling property is improved.

1 Cylinder 2 Mounting hole 21 Inward protrusion 21a Guide part 21b Minimum inner diameter part 3 Soft member 31 Inner hole 32 Friction part 4 Large diameter part 41 Shoulder part 5 Small diameter part 51 Outward protrusion 51a Guide part 51b Maximum outer diameter part 52 Protruding part 53 Lower extension part 6 Circular space 7 Central core 71 Ventilation part 72 Upper core part 73 Lower core part A Axial length from the lower end of the large diameter part to the upper end of the outward protrusion B From the upper end of the cylinder to the lower end of the introvert Axial length C Axial gap

Claims (8)

It is a mounting structure of a soft member that attaches a soft member to the upper end of the barrel of a writing instrument or the cylinder of a cap.
A mounting hole that opens upward in the axial direction is provided at the upper end of the cylinder, an inward protrusion is formed on the inner peripheral surface of the mounting hole, and an outward protrusion is formed on the outer peripheral surface of the soft member. The inward projection is locked in the vertical direction to prevent it from coming off, the soft member is provided with an inner hole that opens in the axial direction, a core is inserted into the inner hole, and the core is in a non-contact state with the cylinder. The core is located at least inward in the radial direction of the outward protrusion, the outer peripheral surface of the core is pressed against the inner peripheral surface of the inner hole, and the upper end of the core is of the cylinder. The mounting structure for a soft member according to claim 1, which is located at the same position as the upper end portion or below the upper end portion of the cylinder. The mounting structure for a soft member according to claim 1, wherein the inner hole opens downward in the axial direction, the soft member is a bottomed tubular body, and the core is provided with a ventilation portion penetrating in the axial direction. The soft member mounting structure according to claim 1 or 2, wherein the core has a symmetrical shape in the vertical direction. The soft member mounting structure according to claim 2, wherein the ventilation portion is a through hole that penetrates inside the core in the axial direction. The soft member mounting structure according to claim 2, wherein the ventilation portion is provided on the outer peripheral surface of the core and is a groove or a protrusion penetrating in the axial direction. The outer peripheral surface of the soft member is composed of a large-diameter portion, a small-diameter portion integrally connected below the large-diameter portion, and a shoulder portion formed between the large-diameter portion and the small-diameter portion. The soft member mounting structure according to any one of claims 1 to 5, wherein the outward protrusion is formed on the outer peripheral surface of the small diameter portion. The soft member mounting structure according to any one of claims 1 to 6, wherein the lower end portion of the core is at the same position in the vertical direction as the lower end portion of the soft member or does not project downward from the lower end portion of the soft member. .. The mounting structure for a soft member according to any one of claims 1 to 7, wherein a protrusion is provided on the outer peripheral surface of the core.

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