JP5972117B2 - Cylindrical body and shaft cylinder having anti-rotation mechanism - Google Patents

Description

  The present invention relates to a cylindrical body such as a writing instrument cap having a rotation preventing mechanism and a shaft cylinder.

  In a shaft cylinder to be connected by screwing together molded products made of non-elastic resin such as polycarbonate and ABS, a so-called undercut engagement groove is formed inside one molded product, By applying an elastic part such as an O-ring as a lock to the inside of the locking groove and pressing the other molded product to be connected in the radial direction, the relative rotation between these molded products is prevented and screwing is performed. A shaft tube structure that prevents loose connection is known (see Patent Document 1).

JP 2009-61630 A

  However, in the configuration as described above, an elastic part such as an O-ring is required, and a process for inserting the elastic part into the locking groove is required for manufacturing. In addition, it is necessary to create a locking groove by undercut. As a result, there is a risk that cracks may be generated in the molded product due to the force continuously applied by the elastic member, and it may be difficult to manage the dimensions of the molded product.

  Accordingly, an object of the present invention is to provide a cylindrical body having a rotation preventing mechanism for preventing relative rotation between components without requiring an elastic member such as an O-ring separately, and a shaft cylinder including the cylindrical body. There is to do.

In order to solve the above problems, according to the present invention,
A cylindrical body formed by connecting a first part to a second part,
The first part is composed of a primary molded product formed by primary molding and a secondary molded product molded on either the outer surface or the inner surface of the primary molded product by secondary molding,
The secondary molded product is made of an elastic body, and includes a convex portion projecting radially from the surface,
When the first component and the second component is connected, the front surface of the second part abut each other facing the convex portion,
A tubular body is provided.

Furthermore, according to the present invention,
A shaft cylinder including the above-described cylindrical body,
The first part is either the front axle or the rear axle, and the second part is either the rear axle or the front axle,
A shaft tube is provided.

  According to the present invention, it is possible to provide a cylindrical body having an anti-rotation mechanism for preventing relative rotation of components and a shaft cylinder including the cylindrical body without separately requiring an elastic member such as an O-ring. .

The front view of the writing instrument to which the axial cylinder which concerns on embodiment of this invention was applied. FIG. 2 is a component diagram of the shaft cylinder of FIG. 1. Sectional drawing of the axial cylinder of FIG. The enlarged view of the front axis | shaft of the state which is not connected with the rear axis | shaft of the axial cylinder of the X part of FIG. The enlarged view of the X section of FIG. The figure similar to FIG. 4 of a modification.

  The invention will be described in more detail with reference to the above-mentioned drawings. It should be noted that the drawings may be drawn differently from actual component sizes, scales, and shapes in order to facilitate understanding of the present invention and simplify the description of the drawings.

  An embodiment of the present invention will now be described with reference to FIGS. FIG. 1 is a front view of a writing instrument 100 to which a shaft cylinder 1 which is an embodiment of the cylindrical body of the present invention is applied, and shows a knock-type ballpoint pen as an example. For convenience of explanation, in this specification, as shown in FIG. 1, the tip, that is, the pen tip side of the writing instrument 100 is defined as the “front” side of the writing instrument 100, and the pen of the writing instrument 100 is aligned along the axis L of the writing instrument 100. The opposite side to the front is defined as the “rear” side of the writing instrument 100.

  The writing instrument 100 of FIG. 1 is disposed inside a shaft cylinder 1 that is configured by mounting a ballpoint pen tip on a front end portion of a shaft cylinder 1 that extends in the front-rear direction and an ink storage pipe that stores ink for writing instruments. A refill (not shown) and a clip portion 3 provided at the rear end portion of the shaft tube 1. By moving the clip part 3 in the front-rear direction against the urging force of a spring (not shown) disposed inside the shaft cylinder 1 that urges the refill rearward, the front end part of the shaft cylinder 1 is moved. You can move forward and backward.

  FIG. 2 is a component diagram of the shaft cylinder 1 which is an embodiment of the cylindrical body of the present invention. The shaft cylinder 1 has a cylindrical front shaft 5 and a rear shaft 7, and the front shaft 5 is a molded product that is injection-molded by a two-color molding technique. In FIG. 2, the front shaft 5 has a tip part exposed on the outer surface, for example, a first molded product 10 that forms a shaft body, and a second molded product that is mounted on the outer peripheral surface of the front shaft 5 and forms a grip portion, for example. 20.

  FIG. 3 is a cross-sectional view of FIG. In FIG. 3, components such as the clip portion and the refill and spring inside the shaft cylinder are omitted. The outer diameter of the front shaft 5 gradually decreases from the front end portion thereof to a tapered shape as a whole. By engaging the screw portion 6 provided on the outer peripheral surface of the rear end portion of the front shaft 5 with the screw portion 8 provided on the inner peripheral surface of the front end portion of the rear shaft 7, The shaft 7 is screwed. Therefore, the rear shaft 7 can be attached to and detached from the front shaft 5, and the refill inside the shaft tube can be easily replaced by removing the rear shaft 7 from the front shaft 5.

  The secondary molded product 20 is mounted on the outer peripheral surface of the primary molded product 10 by two-color molding. That is, the secondary molded product 20 is integrally fused to the primary molded product 10 so as to cover the outer peripheral surface of the primary molded product 10.

  The first molded product 10 has a flange portion 10f protruding in the radial direction at a position adjacent to the front end portion of the rear shaft 7 when the front shaft 5 and the rear shaft 7 are connected. The thickness of the secondary molded product 20 mounted on the flange portion 10f is reduced by the amount of protrusion of the flange portion 10f. However, the flange portion 10f is not necessarily required, and the outer diameter of the first molded product 10 may be the same as the adjacent portion in the portion.

  In the present embodiment, the primary molded product 10 is made of a hard resin material such as polypropylene or polycarbonate, and the rear shaft 7 is also made of the same resin material as the primary molded product 10. The secondary molded product 20 is made of, for example, a relatively soft resin material such as a thermoplastic elastomer or a thermosetting rubber, that is, an elastic material having a property generally called rubber elasticity. For this reason, the elastic modulus of the secondary molded product 20 is smaller than the elastic modulus of the primary molded product 10 and the rear shaft 7. Note that the rear shaft 7 can be made of a material different from that of the primary molded product 10, and more specifically, the rear shaft 7 may not be manufactured by a molding technique.

  FIG. 4 shows an enlarged view of the front shaft 5 of the shaft cylinder 1 in the X part of FIG. 3 in a state where it is not connected to the rear shaft 7. Referring to FIG. 4, the secondary molded product 20 is formed so that the primary molded product 10 extends from the front of the front shaft 5 to the front of the screw portion 6 positioned at the rear end of the first molded product 10, beyond the flange portion 10 f. It is covered. Here, the part which is located between the flange part 10f and the screw part 6 and whose thickness is thinner than the part located in front of this is defined as the rear end part 20r of the second molded product 20. To do. In this embodiment, the rear end portion 20r of the second molded product 20 is provided with a hemispherical convex portion 21 protruding outward in the radial direction.

  FIG. 5 shows an enlarged view of a portion X in FIG. 3 in a state where the front shaft 5 and the rear shaft 7 are screwed together. When the rear shaft 7 is connected to the front shaft 5, before the connection, the convex portion 21 having the shape shown by the dotted line in FIG. 5 is connected to the rear end portion 20r of the second molded product 20, and thus The inner surface 7i of the rear shaft 7 facing the convex portion 21 is abutted and compressed, and deformed so as to be crushed in the radial direction. As described above, since the first molded product 10 is made of a material harder than the second molded product 20 and the second molded product 20 is made of an elastic material, the convex portion 21 is mainly in the radial direction. As a result, the force corresponding to the deformation amount of the convex portion 21 is applied to the portion where the convex portion 21 and the inner surface 7i of the rear shaft 7 abut.

  The protruding height of the convex portion 21 is such that the convex portion 21 and the inner surface 7i of the rear shaft 7 abut against each other so that a desired force is generated, and the convex portion 21 inserts the front shaft 5 into the rear shaft 7. It is decided not to become an obstacle. In addition, the protrusion height of this convex part 21 is determined from the material of the 1st molded product 10 and the 2nd molded product 20, the dimension error etc. which a product accept | permits. As an example, the convex portion 21 may have a height of 0.1 mm with respect to the front shaft 5 having an outer diameter of 10 mm at the portion.

According to this embodiment, the following operational effects can be achieved.
(1) The frictional force is generated between the front shaft 5 and the rear shaft 7 in the rotational direction by causing the convex portion 21 to abut against the inner surface 7i of the rear shaft 7 and deform to generate a radial force. Thus, relative rotation between the front shaft 5 and the rear shaft 7 can be prevented. In the case of this embodiment, it acts as a loosening prevention of the screw connection between the front shaft 5 and the rear shaft 7.
(2) Since the convex portion 21 provided on the secondary molded product 20 of the front shaft 5 provides an anti-rotation action, an elastic part such as a separate O-ring and a component of the shaft cylinder is not required, and the manufacturing process is performed. It can be reduced and there is no extra manufacturing cost.

  (3) When an elastic part is used, it is necessary to provide a locking groove by undercut in order to enclose the elastic part and prevent its falling off (see Patent Document 1). Since the member of the molded product becomes thin in the groove portion, there is a possibility that a crack may be generated in the portion when the elastic force is continuously applied from the elastic component. On the other hand, since it is not necessary to make the molded product thin in this embodiment, the problem of the crack does not occur.

  (4) Since the convex portion 21 is made of an elastic material, compared to the case where the convex portion 21 is made of an inelastic material, there is less load on the counterpart member when the convex portion interferes, so the counterpart member Cracks are unlikely to occur, and it is not necessary to strictly control the height of the protrusion.

  In the present embodiment, the shape of the convex portion 21 is a hemispherical shape, but may be any shape such as a pyramid shape, a conical shape, or a cylindrical shape as long as the above-described effects can be exhibited. Moreover, the convex part 21 may be elongated and may be provided on the entire outer periphery.

  FIG. 6 shows a first modification of the above-described embodiment. In the first modification, in order to provide the convex portion 21, the rear end portion 20r of the second molded product 20 is provided with a gate position 23 corresponding to the position of the gate of the second molding die for injection molding. be able to. In the process of forming the second molded product of the front shaft 5, when the secondary molded product that has been cooled and formed is separated from the secondary molding die, secondary molding is performed by the gate edge of the secondary molding die. The product is cut from the runner, and the secondary molded member is slightly left on the surface of the second molded product 20 so as to protrude from the surface. The remaining gate portion of the secondary molded member is defined as “gate remaining portion”, and is used in common in the present specification and claims. In the first modification, the remaining gate portion protrudes from the surface of the rear end portion 20 r of the second molded product 20 to form the convex portion 21.

  In the first modified example, since the remaining gate portion is used for the convex portion 21, there is no need to worry about the gate processing, and there is an advantage that the restrictions on the molding die structure are reduced.

  Although not particularly shown, as a second modification, the front shaft 5 and the rear shaft 7 can be joined by a conventional snap fit. In a normal snap fit, the front shaft 5 and the rear shaft 7 can freely rotate relative to each other. However, in the second modification, the above-described convex portion 21 is provided to prevent such rotation. can do. Thereby, the user can hold | maintain a shaft cylinder stably.

  In the above-described embodiment, the front shaft 5 is molded by the two-color molding technique, but the rear shaft 7 may be molded by the two-color molding technique. In this case, the components of the front shaft 5 and the rear shaft 7 are reversed, and the convex portion 21 provided at the front end portion of the secondary molded product of the rear shaft 7 formed by the two-color molding technique is included in the front shaft 5. It will be in contact with the surface and constitute an anti-rotation mechanism.

  Furthermore, in the above-described embodiment, the convex portion 21 is provided on the outer surface of the front shaft 5, but the convex portion 21 having a shape protruding radially inward may be provided on the inner surface of the front shaft 5. At this time, the secondary molded product 20 of the front shaft 5 molded by the two-color molding technique is molded so as to cover the inner surface of the primary molded product 10. And when the convex part 21 is provided in the inner surface of the front shaft 5, the convex part 21 contact | abuts with the outer surface of the rear axis | shaft 7 which opposes this, and comprises a rotation prevention mechanism. Also in this case, the components of the front shaft 5 and the rear shaft 7 may be reversed.

  In the above-described embodiment, the front shaft 5 is molded using a two-color molding technique. However, the front shaft 5 uses a so-called multicolor molding technique of two or more colors so as to constitute the above-described rotation prevention mechanism. The rear shaft 7 or both the front shaft 5 and the rear shaft 7 may be molded by a two-color molding technique or a multicolor molding technique.

  In the above description, the shaft cylinder having the above-described configuration and applied to the knock type ballpoint pen has been described. However, the cylindrical body of the present invention is similarly applied to the shaft cylinder of other writing instruments such as a mechanical pen and a fountain pen. be able to. The rotation prevention mechanism of the present invention can also be used when connecting the shaft tube and its cap. Or the cylindrical body of this invention is applicable similarly to cylindrical bodies other than writing instruments, such as cosmetics. That is, as long as the features and functions of the present invention can be realized, the cylindrical body of the present invention is not limited to the shaft cylinder of the embodiment.

1 Shaft cylinder (tubular body)
5 Front shaft 7 Rear shaft 10 First molded product 20 Second molded product 21 Projection

Claims (3)

A cylindrical body formed by connecting a first part to a second part,
The first part is composed of a primary molded product formed by primary molding and a secondary molded product molded on either the outer surface or the inner surface of the primary molded product by secondary molding,
The secondary molded product is made of an elastic body, and includes a convex portion projecting radially from the surface,
When the first part and the second part are connected, the convex part and the surface of the second part facing each other abut each other.
In the tubular body,
The convex portion is a gate remaining portion of the secondary molded product of the first component.
Tubular body. The first part and the second part are connected by screwing or by a snap fit,
The cylindrical body according to claim 1 . A shaft cylinder including the cylindrical body according to claim 1 ,
The first part is either the front axle or the rear axle, and the second part is either the rear axle or the front axle,
Shaft cylinder.

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