Shaft cylinder for writing instrument and writing instrument equipped with this shaft cylinder for writing instrument

Abstract

To maintain a good fitting state of an outer cylinder with respect to an inner cylinder.SOLUTION: The writing instrument barrel includes an inner cylinder 11 and an outer cylinder 12 annularly covering the inner cylinder 11. The outer peripheral portion of the inner cylinder 11 is provided with a first protrusion 11d that protrudes radially outward. The first protrusion 11 d is formed to be elastically deformable in the radial direction of the barrel, and is pressed against the inner peripheral surface of the outer cylinder 12. A second protrusion 11e having a smaller protrusion amount than the first protrusion 11d is provided on the outer peripheral portion of the inner cylinder 11 at a position different from that of the first protrusion 11d.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a barrel for writing instruments that constitutes the outer peripheral portion of writing instruments such as ballpoint pens, mechanical pencils, and marking pens, and a writing instrument equipped with this barrel for writing instruments.

Background Art

[0002] Conventionally, in this type of invention, as described in Patent Document 1 for example, there is one in which a grip (outer cylinder) made of a relatively hard synthetic resin material is fitted to the outer peripheral portion of a substantially cylindrical shaft cylinder (inner cylinder) from the front side. In this prior art, by limiting the dimensions of the protrusion on the front end side of the shaft cylinder and the dimensions of the tapered portion on the rear end side of the grip, etc., the assemblability when fitting the hard grip to the shaft cylinder is improved, and the holding property after assembly is also said to be good.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the grip attached to the outer peripheral portion of the shaft cylinder may have a change in the radial dimension of each part due to manufacturing variations or the like. Also, the wall thickness may change due to a change in the material in terms of design, and accordingly, the inner and outer diameter dimensions may change. Furthermore, depending on the application, the inner and outer diameters and the wall thickness of the grip may be changed in design. And when the radial dimension of the grip changes in this way, if the dimension of the corresponding outer peripheral portion of the shaft cylinder is not changed, there is a risk that the grip may fit too tightly or too loosely with respect to the shaft cylinder.

Means for Solving the Problems

[0005] In view of such problems, the present invention has the following configuration. It includes an inner cylinder and an outer cylinder that annularly covers the inner cylinder. On the outer peripheral portion of the inner cylinder, a first protrusion that protrudes radially outward is provided. The first protrusion is formed to be elastically deformable in the radial direction of the shaft cylinder and is in pressure contact with the inner peripheral surface of the outer cylinder. A barrel for a writing instrument, wherein the first protrusion has a deformed portion that is elastically deformed radially inward by being pressed against the inner peripheral surface of the outer cylinder, and a hollow portion that is located radially inward of this deformed portion. The barrel for a writing instrument is characterized by this.

Effects of the Invention

[0006] Since the present invention is configured as described above, even when the radial dimension changes, the fitting state of the outer cylinder with respect to the inner cylinder can be maintained well.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0008] In the present embodiment, the following features are disclosed. The first feature is that it includes an inner cylinder and an outer cylinder that annularly covers the inner cylinder. On the outer peripheral portion of the inner cylinder, a first protrusion that protrudes radially outward is provided. The first protrusion is formed to be elastically deformable in the radial direction of the shaft cylinder and is in pressure contact with the inner peripheral surface of the outer cylinder (see FIGS. 1 to 2).

[0009] As the second feature, the first protrusion has a deformed portion that is in pressure contact with the inner peripheral surface of the outer cylinder and is elastically deformed radially inward, and a hollow portion that is located radially inward of this deformed portion (see FIGS. 2 and 3).

[0010] As a third feature, the first protrusion is formed in a doubly supported beam shape straddling the hollow portion (see FIGS. 2 and 3).

[0011] As a fourth feature, the deformed portion has small protrusions that partially protrude radially outward and are pressed against the inner peripheral surface of the outer cylinder (see FIGS. 2 and 4).

[0012] As a fifth feature, the first protrusion and the second protrusion are provided on the outer peripheral portion of the inner cylinder, and the protruding amount of the second protrusion is smaller than that of the first protrusion (see FIGS. 1 to 4).

[0013] As a sixth feature, the outer cylinder is a hard grip provided at a gripping portion (see FIG. 1).

[0014] As a seventh feature, a writing instrument is configured by including the above-described shaft cylinder for a writing instrument (see FIG. 1).

[0015] An eighth feature is a method for manufacturing the above-described writing instrument, which includes a step of covering the outer cylinder annularly from one side in the axial direction of the shaft cylinder and elastically deforming the first protrusion radially inward (see FIG. 3).

[0016] <Specific Embodiments> Next, specific embodiments having the above features will be described in detail with reference to the drawings.

[0017] In this specification, the axial direction of the shaft cylinder means the direction in which the center line of the shaft cylinder extends, and the circumferential direction of the shaft cylinder means the direction of going around the center line of the shaft cylinder. Further, "front" means one side in the axial direction of the shaft cylinder and the direction in which the writing portion protrudes, and "rear" means the opposite side to the one side. Also, in this specification, the radial direction of the shaft cylinder means the diameter direction of the shaft cylinder orthogonal to the center line of the shaft cylinder. And the radially outer side of the shaft cylinder means the direction of separating from the shaft cylinder center along the radial direction of the shaft cylinder, and the radially inner side of the shaft cylinder means the direction of going toward the shaft cylinder center along the radial direction of the shaft cylinder.

[0018] FIG. 1 shows an example of a writing instrument including a shaft cylinder for a writing instrument according to the present invention. This writing instrument 1 includes a shaft cylinder 10 for a writing instrument, a tip 20 attached to the front end side of the shaft cylinder 10 for a writing instrument, a refill 30 movably housed within the shaft cylinder 10 for a writing instrument, and an advancing / retreating mechanism 40 for causing the refill 30 to project and retract at the front end of the tip 20 by an external operation.

[0019] The shaft cylinder 10 for a writing instrument is formed in a long cylindrical shape from a front shaft 10a and a rear shaft 10b connected to the rear end side of the front shaft 10a.

[0020] The front shaft 10a is composed of a double cylinder shape from an inner cylinder 11 and an outer cylinder 12 that annularly covers the inner cylinder 11. Note that the inner cylinder 11 can also be integrally formed on the front end side of the rear shaft 10b.

[0021] The inner cylinder 11 is molded from a synthetic resin material and integrally includes a long substantially cylindrical tube body 11f continuous in the front-rear direction, a flange portion 11c protruding radially outward from the tube body 11f, first protrusions 11d, 11d', and a second protrusion 11e.

[0022] A plurality (two in the illustrated example) of the first protrusions 11d, 11d' are provided at a predetermined interval in the front-rear direction. One of the first protrusions 11d is located forward, and the other first protrusion 11d' is located rearward of the first protrusion 11d. One of the first protrusions 11d and the other first protrusion 11d' are both provided with a plurality (two in the illustrated example) at equal intervals in the radial direction. These first protrusions 11d, 11d' are elastically deformed radially inward by being pressed against the inner peripheral surface of the outer cylinder 12.

[0023] The first protrusions 11d, 11d' have a deformed portion 11d1 that is elastically deformed radially inward by being pressed against the inner peripheral surface of the outer cylinder 12, and a hollow portion 11d2 located radially inward of the deformed portion 11d1, and are configured in a double-cantilever shape straddling the hollow portion 11d2. The front end portion of each first protrusion 11d (or 11d') is formed in a protruding curved surface shape so as to facilitate insertion into the outer cylinder 12.

[0024] Each deformed portion 11d1 is configured to be elongated in the axial cylinder direction. The deformed portion 11d1 of one of the first protrusions 11d is formed in a U shape in a side view with the radially inner side open, and its front end side and rear end side are connected to the outer peripheral surface of the cylinder main body 11f (see FIGS. 2 and 3).

[0025] The deformed portion 11d1 of the other first protrusion 11d' is formed in an L shape in a side view with the radially inner side open, and one end side thereof is connected to the outer peripheral surface of the cylinder main body 11f, and the other end side is connected to the flange portion 11c (see FIGS. 2 and 3).

[0026] At a substantially central position in the front-rear direction of each deformed portion 11d1, small protrusions 11d11 that partially protrude radially outward and are pressed against the inner peripheral surface of the outer cylinder 12 are provided. This deformed portion 11d1 is formed in a convex curved surface shape, reducing the resistance against the inner peripheral surface of the outer cylinder 12.

[0027] The second protrusions 11e are provided in a plurality (two in the illustrated example) at a predetermined interval in the front-rear direction at different circumferential positions from the first protrusions 11d, and are provided in a plurality (two in the illustrated example) at equal intervals in the circumferential direction. (According to the illustrated example, there are two).

[0028] In addition, as another example other than the illustrated example, the circumferential positions of the first protrusions 11d and the second protrusions 11e may be the same.

[0029] Each second protrusion 11e is formed in an elongated rib shape extending in the front-rear direction of the axial cylinder. This second protrusion 11e does not have a hollow portion and does not elastically deform like the first protrusion 11d. Each second protrusion 11e is located at a substantially central portion between two adjacent first protrusions 11d, 11d (or 11d', 11d') in the circumferential direction of the axial cylinder. This second protrusion 11e has a smaller protrusion amount radially outward of the axial cylinder than the first protrusion 11d and is in proximity to the inner peripheral surface of the outer cylinder 12 with a minute gap therebetween (see FIG. 4). The front end portion of this second protrusion 11e is formed in a protruding curved surface shape so as to facilitate insertion into the outer cylinder 12.

[0030] The outer cylinder 12 is formed in a cylindrical shape from a hard metal material (for example, copper alloy, brass, aluminum alloy, etc.). This outer cylinder 12 is located at the gripping part of the writing instrument 1 and constitutes a grip that is grasped by a finger.

[0031] Also, the tip 20 is a substantially cylindrical member with a tapered outer peripheral surface and is connected to the front end side of the inner cylinder 11. An annular receiving part 21 is provided on the outer peripheral surface on the rear end side of this tip 20 to annularly receive the inner peripheral surface on the front end side of the outer cylinder 12 over the entire circumference.

[0032] For the advancing and retracting mechanism 40, it is possible to apply a well-known structure of a retractable ballpoint pen, such as the structure described in Japanese Patent Application Laid-Open No. 2018-149787.

[0033] Next, regarding the writing instrument 1 having the above configuration, the effects during assembly and the effects during use will be described. When assembling the outer cylinder 12 to the inner cylinder 11, the outer cylinder 12 is mounted so as to be annularly covered from the front side with respect to the inner cylinder 11 (see FIG. 3). In other words, the inner cylinder 11 is inserted into the outer cylinder 12 from the rear side. At this time, each first protrusion 11d (or 11d') elastically bends and deforms toward the hollow part 11d2 side (in other words, the radially inner side) by sliding the small protrusion 11d11 along the inner peripheral surface of the outer cylinder 12.

[0034] Therefore, even when the inner diameter of the outer cylinder 12 or the protruding amount of the first protrusions 11d, 11d' varies due to manufacturing errors or the like, the elastic deformation of the first protrusions 11d, 11d' can make the resistance during the mounting and insertion relatively small, and the assemblability is good.

[0035] Also, even when the inner diameter of the outer cylinder 12 changes due to design changes such as design modifications or material changes, the first protrusions 11d, 11d' elastically contract and recover in the axial cylinder radial direction, so it is possible to prevent the assemblability from being impaired. Therefore, it is not necessary to change the design on the inner cylinder 11 side.

[0036] Further, when the outer cylinder 12 in a state of being attached to the inner cylinder 11 receives an external force toward the radially inner side, the inner peripheral surface of the outer cylinder 12 abuts against the tip of the second protrusion 11e. Therefore, for example, even when the gripping force when gripping the outer cylinder 12 is too large, deformation and breakage of the outer cylinder 12 can be prevented.

[0037] Therefore, according to the pen shaft cylinder having the above configuration, not only is the assemblability good, but also the fitting state of the outer cylinder 12 with respect to the inner cylinder 11 can be maintained well even when the radial dimension changes.

[0038] <Other Modification Examples> According to the above embodiment, the double cylinder structure including the inner cylinder 11 and the outer cylinder 12 is formed in the gripping portion on the front side of the pen shaft cylinder 10. However, as another example, the double cylinder structure can also be formed in the entire pen shaft cylinder 10 or on the rear side.

[0039] Further, according to the pen shaft cylinder 10 of the above embodiment, as a preferable aspect for reducing the eccentricity of the outer cylinder 12 with respect to the inner cylinder 11, a plurality of first protrusions 11d, 11d' and second protrusions 11e are provided in the circumferential direction of the shaft cylinder. However, as another example, it is also possible to adopt an aspect in which either one or both of these first protrusions and second protrusions are provided singly in the circumferential direction.

[0040] Further, according to the pen shaft cylinder 10 of the above embodiment, as a particularly preferable aspect, a plurality of first protrusions 11d, 11d' and second protrusions 11e are provided in the axial direction of the shaft cylinder. However, as another example, it is also possible to adopt an aspect in which either one or both of these first protrusions and second protrusions are made single.

[0041] Further, according to the above embodiment, as an aspect in which the operational effects of the present invention can be remarkably obtained, the outer cylinder 12 is formed of a hard material. However, as another example, it is also possible to form the outer cylinder 12 of a soft material or an elastic material.

[0042] Further, the double cylinder structure including the above inner cylinder and the above outer cylinder can be applied to pens other than the illustrated example.

[0043] As another example of the first protrusion, the deformation part may be formed in a substantially cylindrical shape that surrounds the outer peripheral surface of the cylindrical main body with one end side in the axial direction of the shaft cylinder as a free end through a hollow part, and the other end side of this deformation part may be connected to the cylindrical main body.

[0044] Further, the present invention is not limited to the above-described embodiments, and can be appropriately changed without changing the gist of the present invention.

Explanation of Reference Numerals

[0045] 1: Writing instrument 10: Shaft cylinder for writing instrument 11: Inner cylinder 11d, 11d’: First protrusion 11d11: Small protrusion 11e: Second protrusion 12: Outer cylinder

Claims

1. comprising an inner cylinder and an outer cylinder that annularly covers the inner cylinder, wherein a first protrusion that protrudes radially outward is provided on the outer peripheral portion of the inner cylinder, and the first protrusion is formed to be elastically deformable in the radial direction of the shaft cylinder and is in pressure contact with the inner peripheral surface of the outer cylinder, and is a shaft cylinder for a writing instrument, wherein the first protrusion has a deformed portion that is elastically deformed radially inward by being in pressure contact with the inner peripheral surface of the outer cylinder, and a hollow portion that is located radially inward of the deformed portion, and is a shaft cylinder for a writing instrument.

2. The shaft cylinder for a writing instrument according to claim 1, wherein the first protrusion is formed in a double cantilever beam shape straddling the hollow portion.

3. The shaft cylinder for a writing instrument according to claim 1 or 2, wherein the deformed portion has small protrusions that partially protrude radially outward and are in pressure contact with the inner peripheral surface of the outer cylinder.

4. The shaft cylinder for a writing instrument according to any one of claims 1 to 3, wherein a first protrusion and a second protrusion are provided on the outer peripheral portion of the inner cylinder, and the second protrusion has a smaller protrusion amount than the first protrusion.

5. The shaft cylinder for a writing instrument according to any one of claims 1 to 4, wherein the outer cylinder is a grip provided at a gripping portion.

6. A writing instrument comprising the shaft cylinder for a writing instrument according to any one of claims 1 to 5.

7. A method for manufacturing a writing instrument according to claim 6, comprising the step of annularly covering the outer cylinder from one side in the axial direction of the shaft cylinder with respect to the inner cylinder and elastically deforming the first protrusion radially inward.

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