JP6715564B2 - Knock type writing instrument - Google Patents

Description

The present invention relates to a knock-type writing instrument.

BACKGROUND ART Conventionally, as disclosed in Patent Documents 1 and 2, there is known a knock-type writing instrument in which a pen tip is projected and retracted by knocking (knocking operation) a rear end portion of the writing instrument. The knock-type writing instrument includes a knock mechanism including an outer cam formed on the inner peripheral surface of the barrel, a knock rod protruding rearward from the barrel, and a rotor arranged in the barrel.

FIGS. 6A to 6C are a front view, a plan view and a bottom view of a rotor 8a according to a conventional technique, respectively. FIG. 7 is a cross-sectional view taken along the line BB of FIG. The rotor 8a has an insertion portion 81a that is inserted into the knock rod and a cam portion 82a that engages with the knock rod.

The cam portion 82a is formed with a cam receiving surface 83a with which the cam surface of the knock bar abuts and an inner cam 84a with which the outer cam is engaged. Therefore, the cam portion 82a is required to have high dimensional accuracy. In general, when a component is molded by injection molding, a molding defect called "sink" may occur in a thick portion of the component. Therefore, in order to suppress the occurrence of defective molding of the cam portion 82a, it is preferable that the inside of the cam portion 82a be hollow and the thickness of the cam portion 82a be as uniform and thin as possible.

The ink of the writing instrument is ejected from the pen tip by the pressure of air. For this reason, a through hole 87 extending in the front-rear direction is formed in the rotor 8a in order to send air through the rotor 8a into the ink containing tube which is in contact with the rotor 8a.

JP, 2012-210745, A Utility model registration No. 3159535

However, when molding the rotor by injection molding, the core pin extends inside the rotor and the cavity is arranged outside the rotor. Therefore, the rear end of the insertion portion is a mating surface between the core pin and the cavity, a so-called parting surface. Generally, when a gap is generated on the parting surface, the resin flows into the gap and a burr is formed on the molded product. In the conventional rotor having the rear end of the insertion portion as the parting surface, a burr extending rearward from the insertion portion may be formed.

In a knock-type writing instrument assembled using a rotor having a burr, the burr may come into contact with the knock bar and prevent the rotor, and hence the pen tip, from retracting. In this case, knocking causes a knocking failure in which the pen tip cannot be retracted into the barrel.

Therefore, the present invention has been made in view of the above problems, and it is possible to suppress the occurrence of defective molding of the rotor such as sink marks and burrs without deteriorating the ink ejection performance. The purpose is to provide.

According to the first aspect of the present invention, the outer cam formed on the inner peripheral surface of the shaft cylinder, the knock rod protruding rearward from the shaft cylinder and having the cam surface, and the rotor arranged in the shaft cylinder. A cam receiving surface having a shape complementary to the cam surface and an inner cam are formed on the cam portion. , The inner cam is configured to engage or disengage with the outer cam in the front-rear direction when the rotor is rotated by the cam surface pressing the cam receiving surface. In a knock-type writing instrument provided with a mechanism, the rotor has a hollow portion and a ventilation path extending radially outward from the hollow portion to the outer surface of the rotor, and the hollow portion is at least the cam portion from the front end of the cam portion. Provided is a knock-type writing instrument, which is characterized in that it extends to the rear end of the insertion portion and the rear end of the insertion portion is closed.

In the first aspect of the present invention, it is preferable that the air passage extends radially outward from the hollow portion to the outer surface of the rotor at the front end of the cam portion.

According to the present invention, since the rotor has the hollow portion and the inside of the cam portion of the rotor is hollow, it is possible to suppress the occurrence of sink marks in the cam portion. Further, since the rear end of the insertion portion is closed, no parting surface is formed at the rear end of the insertion portion, and it is possible to suppress the occurrence of burrs at the rear end of the insertion portion. Further, since the rotor has a ventilation path that extends radially outward from the hollow portion to the outer surface of the rotor, it is possible to send air to the ink containing tube through the rotor and ensure ink ejection performance. can do. Therefore, according to the present invention, there is provided a knock-type writing instrument that can suppress the occurrence of defective molding of the rotor such as sink marks and burrs without deteriorating the ink ejection performance.

1A to 1C are a front view, a plan view and a bottom view of a rotor according to an embodiment of the present invention, respectively. FIG. 2 is a sectional view taken along the line AA of FIG. 3A and 3B are a front view and a right side view, respectively, of a knock-type writing instrument according to the related art. FIG. 4 is a schematic exploded perspective view of a knock-type writing instrument according to the related art. FIG. 5 is an enlarged exploded perspective view of the inner cylinder, the knock rod, and the rotor. 6A to 6C are a front view, a plan view and a bottom view of a rotor according to a conventional technique, respectively. FIG. 7 is a cross-sectional view taken along the line BB of FIG.

First, a knock-type writing instrument according to the related art will be described with reference to FIGS. 3 and 4. The knock-type writing instrument according to the present invention has the same configuration as the knock-type writing instrument according to the related art except for the shape of the rotor.

FIG. 3A and FIG. 3B are a front view and a right side view of a knock-type writing instrument 1 according to the related art, respectively. FIG. 4 is a schematic exploded perspective view of a knock-type writing instrument 1 according to the related art. In this example, the knock-type writing instrument 1 is a knock-type ballpoint pen. In addition, as shown in FIG. 3, in the present specification, the tip of the knock-type writing instrument 1, that is, the pen tip side is defined as the “front” side of the knock-type writing instrument 1, and the axial direction (longitudinal direction) of the knock-type writing instrument 1 is defined. The side of the knock type writing instrument 1 opposite to the pen tip is defined as the “rear” side of the knock type writing instrument 1. Also, regarding the components of the knock-type writing instrument 1, in the assembled state of the knock-type writing instrument 1, the pen tip side of the knock-type writing instrument 1 is defined as the “front” side of the component, and along the axial direction of the knock-type writing instrument 1. The side of the knock type writing instrument 1 opposite to the pen tip is defined as the "rear" side of the component.

As shown in FIGS. 3A and 3B, a knock type writing instrument 1 includes a cylindrical barrel 2, a knock cover 3 attached to the rear end of the barrel 2, and a front end of the barrel 2. It is equipped with the attached tipper 4 and a grip rubber 5 formed on the outer peripheral surface of the barrel 2. The cutler 4 is attached to the barrel 2 by, for example, screwing a female screw formed on the inner peripheral face of the cutler 4 with a male screw formed on the outer peripheral face of the front portion of the barrel 2. The grip rubber 5 is typically formed on the outer surface of the barrel 2 by two-color molding. The shaft tube 2 may have the clip 21. Further, the cutler 4 and the barrel 2 may be integrated.

As shown in FIG. 4, the knock-type writing instrument 1 is further fixed to a rear portion of the barrel 2 and an inner barrel 6 that forms a part of the barrel 2; A knock rod 7 protruding rearward from the cylinder 2, a rotor 8a arranged in the inner cylinder 6 and located in front of the knock rod 7, and a shaft cylinder 2 arranged in the front end of the rotor 8a. It is provided with an ink containing tube 9 that is in contact with it, a spring 10 that is arranged in the cutler 4 and biases the ink containing tube 9 rearward, and a ballpoint pen tip 11 that is attached to the front end of the ink containing tube 9. The inner cylinder 6 may be integrated with the shaft cylinder 2.

Hereinafter, with reference to FIG. 5, the configuration and operation of the knock mechanism for retracting the pen tip by knocking the rear end of the writing instrument will be described.

First, the configuration of the knock mechanism will be described. The knock mechanism includes an outer cam 61 formed on the inner peripheral surface of the inner cylinder 6, a knock rod 7, and a rotor 8a. FIG. 5 is an enlarged exploded perspective view of the inner cylinder 6, the knock rod 7, and the rotor 8a.

At the rear portion of the inner peripheral surface of the inner cylinder 6, four outer cams 61 are formed at equal intervals in the circumferential direction, as indicated by the broken line in FIG. Four grooves 62 extending in the front-rear direction are formed between the adjacent outer cams 61. Each outer cam 61 is composed of three rod-shaped portions extending in the front-rear direction and continuously arranged in the circumferential direction. In the second rod-shaped portion 612 arranged in the middle, the protrusion 71 of the knock rod 7 described later is located between the first rod-shaped portion 611 and the third rod-shaped portion 613 at both ends, that is, the second rod-shaped portion 612. Of a radial direction thinner than the first rod-shaped portion 611 and the third rod-shaped portion 613 so as to form a recess between the first rod-shaped portion 611 and the third rod-shaped portion 613 so as to be housed above. It has a thickness. Since the inner cylinder 6 is fixed to the shaft cylinder 2, it does not move by a knocking operation.

Eight protrusions 71 are formed at equal intervals in the circumferential direction on the front portion of the outer peripheral surface of the knock rod 7. Each protrusion 71 moves back and forth in the outer cam 61, more specifically, in the recess between the first rod-shaped portion 611 and the third rod-shaped portion 613 or in the groove 62 between the outer cams 61, by a knocking operation. Configured to slide in a direction. A cam surface 72 is formed at the front end of the knock rod 7. The cam surface 72 has eight peaks 721 and valleys 722. The rear end of the knock bar 7 engages with the knock cover 3. The knock cover 3 may be integrated with the knock rod 7.

The rotor 8 a has an insertion portion 81 a that is inserted into the knock rod 7 for centering the knock rod 7, and a cam portion 82 a that engages with the knock rod 7. The cam portion 82a has a larger outer diameter than the insertion portion 81a. A cam receiving surface 83a having a shape complementary to the cam surface 72 of the knock rod 7 is formed at the rear end of the cam portion 82a. Like the cam surface 72, the cam receiving surface 83a has eight peaks 831a and valleys 832a. On the outer peripheral surface of the cam portion 82a, four inner cams 84a extending in the front-rear direction are formed at equal intervals in the circumferential direction. When the rotor 8a rotates in the circumferential direction by the cam surface 72 pressing the cam receiving surface 83a, the inner cam 84a engages with or disengages the outer cam 61 in the front-rear direction, and the inner cam 84a It is accommodated in the groove 62. When the inner cam 84a is housed in the groove 62 between the outer cams 61, the outer cam 61 is housed in the groove 85a between the inner cams 84a.

Next, the operation of the knock mechanism will be described.

In the state where the pen tip is retracted into the cutler 4, the inner cam 84 a of the rotor 8 a is housed in the groove 62 between the outer cams 61 of the inner cylinder 6. When the knock rod 7 is moved forward against the biasing force of the spring 10 from this state, the cam surface 72 of the knock rod 7 presses the cam receiving surface 83a of the rotor 8a, and the rotor 8a moves forward together with the knock rod 7. .. At this time, the knock rod 7 and the rotor 8a receive forces in the axial direction and the circumferential direction, respectively, via the cam surface 72 and the cam receiving surface 83a. After that, when the rear end of the inner cam 84a exceeds the front end of the outer cam 61, the regulation of the rotor 8a in the circumferential direction is released, so that the rotor 8a is circumferentially moved by the force in the circumferential direction (counterclockwise when viewed from the front). Rotate). On the other hand, the knock rod 7 does not rotate in the circumferential direction because the projection 71 abuts on the outer cam 61 to restrict rotation in the circumferential direction.

When the knock rod 7 is released in this state, the knock rod 7 and the rotor 8a are retracted by the urging force of the spring 10. At this time, the inner cam 84a of the rotor 8a rotated in the circumferential direction engages with the outer cam 61 of the inner cylinder 6 in the front-rear direction. This engagement prevents the rotor 8a from retreating, so that the ball-point pen tip 11 mounted on the ink containing tube 9 that abuts the rotor 8a projects from the cutler 4.

On the other hand, when the pen tip is protruding, the inner cam 84a of the rotor 8a is engaged with the outer cam 61 of the inner cylinder 6 in the front-rear direction. When the knock rod 7 is moved forward against the biasing force of the spring 10 from this state, the cam surface 72 of the knock rod 7 presses the cam receiving surface 83a of the rotor 8a, and the rotor 8a moves forward together with the knock rod 7. .. At this time, the knock rod 7 and the rotor 8a receive forces in the axial direction and the circumferential direction, respectively, via the cam surface 72 and the cam receiving surface 83a. After that, when the rear end of the inner cam 84a exceeds the front end of the outer cam 61, the regulation of the rotor 8a in the circumferential direction is released, so that the rotor 8a is circumferentially moved by the force in the circumferential direction (counterclockwise when viewed from the front). Rotate). On the other hand, the knock rod 7 does not rotate in the circumferential direction because the projection 71 abuts on the outer cam 61 to restrict rotation in the circumferential direction.

When the knock rod 7 is released in this state, the knock rod 7 and the rotor 8a are retracted by the urging force of the spring 10, and the inner cam 84a rotated in the circumferential direction is housed in the groove 62 between the outer cams 61. At this time, the ink containing tube 9 and the ball-point pen tip 11 are also retracted by the urging force of the spring 10, so that the ball-point pen tip 11 is retracted into the cutler 4.

Hereinafter, the shape of the rotor according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2.

1A to 1C are a front view, a plan view and a bottom view of a rotor 8b according to an embodiment of the present invention, respectively. FIG. 2 is a sectional view taken along the line AA of FIG.

The rotor 8b has an insertion portion 81b that is inserted into the knock rod 7 for centering the knock rod 7, and a cam portion 82b that engages with the knock rod 7. The cam portion 82b has a larger outer diameter than the insertion portion 81b. A cam receiving surface 83b having a shape complementary to the cam surface 72 of the knock rod 7 is formed at the rear end of the cam portion 82b. Similar to the cam surface 72, the cam receiving surface 83b has eight peaks 831b and valleys 832b. On the outer peripheral surface of the cam portion 82b, four inner cams 84b extending in the front-rear direction are formed at equal intervals in the circumferential direction. When the rotor 8b rotates in the circumferential direction due to the cam surface 72 pressing the cam receiving surface 83b, the inner cam 84b engages with or disengages the outer cam 61 in the front-rear direction so that the distance between the outer cams 61 is increased. It is accommodated in the groove 62.

The rotor 8b is molded by resin injection molding. The material of the rotor 8b is, for example, polyacetal (POM). As shown in FIG. 2, the rotor 8b has a hollow portion 88. The hollow portion 88 extends from the front end of the cam portion 82b to the middle of the insertion portion 81b beyond the rear end of the cam portion 82b. As a result, the cam portion 82b is lightened (thickness is stolen), so that it is possible to suppress the occurrence of sink marks in the cam portion 82b during molding.

As shown in FIG. 2, the rear portion of the insertion portion 81b is closed. Therefore, the core pin extends partway through the insertion portion 81b, and the tip of the core pin does not come into contact with the cavity provided outside the rotor 8b. Therefore, since the rear end of the insertion portion 81b does not serve as the parting surface, it is possible to prevent the occurrence of burrs at the rear end of the insertion portion 81b. Further, since the length of the core pin can be shortened, the positional accuracy of the core pin in the mold can be improved, and the core pin is less likely to be broken by the pressure during molding.

The rotor 8b further has a ventilation path 86 extending radially outward from the hollow portion 88 to the outer surface of the rotor 8b. Even if the rear end of the insertion portion 81b is closed by the air passage 86, air can be sent to the ink containing tube 9 through the rotor 8b.

In this embodiment, as shown in FIGS. 1A and 1C, two ventilation passages 86 extend radially outward from the hollow portion 88 to the outer surface of the rotor 8b at the front end of the cam portion 82b. In this case, since the ventilation path 86 has a shape that does not cause undercut, the rotor 8b can be molded by a simple two-way punching die that opens in the front-rear direction. The undercut means a convex or concave portion that is caught by the mold when the molded product is taken out from the mold. The number of ventilation paths 86 may be one or more other numbers.

Although the preferred embodiments according to the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims. For example, the knock-type writing instrument may be another writing instrument such as a marker pen as long as it is a type of writing instrument in which the pen tip appears and disappears by a knocking operation.

DESCRIPTION OF SYMBOLS 1 Knocking writing instrument 2 Shaft cylinder 21 Clip 3 Knock cover 4 Cut plastic 5 Grip rubber 6 Inner cylinder 61 Outer cam 611 1st rod part 612 2nd rod part 613 3rd rod part 62 Groove 7 Knock rod 71 Protrusion 72 Cam Surface 721 Mountain part 722 Valley part 8a, 8b Rotor 81a, 81b Insertion part 82a, 82b Cam part 83a, 83b Cam receiving surface 831a, 831b Mountain part 832a, 832b Valley part 84a, 84b Inner cam 85a, 85b Groove 86 Ventilation path 87 Through Hole 88 Hollow Portion 9 Ink Storage Tube 10 Spring 11 Ballpoint Pen Tip

Claims (2)

An outer cam formed on the inner peripheral surface of the shaft cylinder,
A knock bar that projects rearward from the shaft cylinder and has a cam surface,
A rotor provided in the barrel and molded by injection molding , comprising: an insertion portion to be inserted into the knock rod, and a cam portion that engages with the knock rod, Is formed with a cam receiving surface having a shape complementary to the cam surface and an inner cam, and the inner cam rotates the rotor when the cam surface presses the cam receiving surface. In a knock-type writing instrument having a knock mechanism composed of a rotor, which is configured to engage with or disengage from a cam in the front-rear direction,
The rotor has a hollow portion and an air passage extending radially outward from the hollow portion to an outer surface of the rotor, the hollow portion being at least a rear end of the cam portion from a front end of the cam portion. And the rear end of the insertion part is closed ,
The knock-type writing instrument, wherein the air passage extends radially outward from the hollow portion to the outer surface of the rotor at the front end of the cam portion . Before SL in the outer peripheral surface of the cam portion, four said cam extending in the longitudinal direction are formed at equal intervals in the circumferential direction, knock-type writing instrument according to claim 1.

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