JP2016037011A - Knock type writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a knock type writing utensil that can prevent rotors from connecting to each other while suppressing generation of a molding failure of the rotors and furthermore improve productivity of the writing utensil.SOLUTION: The knock type writing utensil is equipped with a knock mechanism comprised of: an outer cam 61 formed on an inner peripheral face of a barrel 2; a knock bar 7 that protrudes rearward from the barrel and has a cam face 72 formed; and a rotor 8b, arranged in the barrel, that has an inserted portion 81b to be inserted into the knock bar 7 and a cam part 82b to be engaged with the knock bar 7. In the cam part 82b are formed a cam receiving face 83b of a shape complementary to the cam face 72, and inner cams 84b. The inner cams 84b are configured to engage with or disengage from the outer cam 61 in a longitudinal direction when the rotor 8b is rotated in a circumferential direction by pressurization of the cam receiving face 83b by the cam face 72. The inside of the cam part 82b is hollow and has a shape that can prevent entering of the inserted part 81b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a knock type writing instrument.

  Conventionally, as disclosed in Patent Documents 1 to 3, a knock type writing instrument is known in which a pen tip is projected and retracted by knocking 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 shaft cylinder, a knock bar protruding rearward from the shaft cylinder, and a rotor disposed in the shaft cylinder.

  9A to 9C are a front view, a plan view, and a bottom view of a rotor 8a according to the related art, respectively. FIG. 10 is a cross-sectional view taken along the line CC in FIG. 9B. The rotor 8a has an insertion portion 81a that is inserted into the knock bar 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. For this reason, the cam part 82a is required to have high dimensional accuracy. Generally, when molding a part by injection molding, a molding defect called “sink” may occur in the thick part of the part. For this reason, it is preferable to make the inside of the cam part 82a hollow and to make the thickness of the cam part 82a as thin as possible in order to suppress the occurrence of molding failure of the cam part 82a. As a result, in the conventional rotor 8a, the inner diameter of the cam portion 82a is larger than the outer diameter of the insertion portion 81a.

JP 2012-210745 A JP 2008-173912 A Utility Model Registration No. 3159535

  By the way, at the time of assembling the writing instrument, the knock bar is first delivered into the shaft cylinder, and then the rotor is delivered into the shaft cylinder. Assembly is performed manually or by an automated machine. In the assembly using the automatic machine, the knock bar and the rotor are delivered into the shaft cylinder by an automatic arm machine, air or the like.

  In the writing instrument production line, a large number of knock bars and rotors are randomly held in the respective containers before assembly. In the conventional rotor, since the inner diameter of the cam portion is larger than the outer diameter of the insertion portion, the insertion portion of the rotor enters the inside of the cam portion of the other rotor in the container, and the rotors are connected to each other. sell. FIG. 11 shows a state where the rotors 8a according to the prior art are connected to each other.

  When the rotor is delivered into the shaft cylinder by an automatic machine, if the rotors are connected to each other, the rotor cannot be delivered into the shaft cylinder. For this reason, the assembly by the automatic machine is interrupted, and an artificial work is required to resume the assembly, so that the productivity of the writing instrument is significantly reduced. Also, in the case of manual assembly, since it is necessary to deliver the rotor into the shaft after uncoupling the rotors, the productivity of the writing instrument similarly decreases.

  Accordingly, the present invention has been made in view of the above-described problems, and prevents the rotors from being connected to each other while suppressing the occurrence of rotor molding defects, thereby improving the productivity of writing instruments. An object of the present invention is to provide a knock-type writing instrument that can be used.

  In the first aspect of the present invention, an outer cam formed on the inner peripheral surface of the shaft tube, a knock bar protruding rearward from the shaft tube and formed with a cam surface, and a rotor disposed in the shaft tube The cam portion includes an insertion portion to be inserted into the knock bar and a cam portion to be engaged with the knock rod. The cam portion has a cam receiving surface complementary to the cam surface and an inner cam. The inner cam is configured to engage or disengage with the outer cam in the front-rear direction when the rotor rotates in the circumferential direction by the cam surface pressing the cam receiving surface; In the knock type writing instrument provided with the knock mechanism, the knock type writing instrument is provided in which the inside of the cam portion is hollow and has a shape that prevents the insertion portion from entering.

  In the first aspect of the present invention, it is preferable that a plurality of ribs protruding radially inward are formed inside the cam portion.

  In the first aspect of the present invention, the circumferential position of the rib is preferably different from the circumferential position of the inner cam.

  According to the present invention, since the inside of the cam portion of the rotor is hollow, it is possible to suppress the occurrence of poor molding of the rotor. Further, since the inside of the cam portion has a shape that prevents the insertion portion from entering, it is possible to prevent the rotors from being connected to each other, thereby improving the productivity of the writing instrument. Therefore, according to the present invention, there is provided a knock type writing instrument that can prevent the rotors from being poorly formed, prevent the rotors from being connected to each other, and thereby improve the productivity of the writing instrument.

1A and 1B are respectively a rear perspective view and a front perspective view of a rotor according to an embodiment of the present invention. 2A to 2C are a front view, a plan view, and a bottom view of the rotor of FIG. 1, respectively. FIG. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 4 is a cross-sectional view taken along line BB in FIG. FIG. 5 shows a state where the rotors according to the embodiment of the present invention are prevented from being connected to each other. 6A and 6B are a front view and a right side view, respectively, of a knock type writing instrument according to the prior art. FIG. 7 is a schematic exploded perspective view of a knock type writing instrument according to the prior art. FIG. 8 is an enlarged exploded perspective view of the inner cylinder, the knock bar, and the rotor. 9A to 9C are a front view, a plan view, and a bottom view, respectively, of a rotor according to the related art. FIG. 10 is a cross-sectional view taken along the line CC in FIG. 9B. FIG. 11 illustrates a state in which the rotors according to the related art are connected to each other.

  First, with reference to FIG.6 and FIG.7, the knock type writing instrument which concerns on a prior art is demonstrated. In addition, the knock type writing instrument which concerns on this invention has the structure similar to the knock type writing instrument which concerns on a prior art except the shape of a rotor.

  6A and 6B are a front view and a right side view, respectively, of the knock type writing instrument 1 according to the related art. FIG. 7 is a schematic exploded perspective view of the knock-type writing instrument 1 according to the prior art. In this example, the knock type writing instrument 1 is a knock type ballpoint pen. As shown in FIG. 6, in this 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. A side opposite to the pen tip of the knock type writing instrument 1 is defined as a “rear” side of the knock type writing instrument 1. In addition, regarding the component parts 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 part, and along the axial direction of the knock type writing instrument 1. The side opposite to the pen tip of the knock type writing instrument 1 is defined as the “rear” side of the component.

  As shown in FIGS. 6A and 6B, the knock type writing instrument 1 includes a cylindrical shaft tube 2, a knock cover 3 attached to the rear end of the shaft tube 2, and a front end of the shaft tube 2. A cutlery 4 mounted and a grip rubber 5 formed on the outer peripheral surface of the shaft cylinder 2 are provided. The cutlery 4 is mounted on the shaft cylinder 2 by, for example, a female screw formed on the inner peripheral surface of the cutlery screw 4 being engaged with a male screw formed on the outer peripheral surface of the front portion of the shaft cylinder 2. The grip rubber 5 is typically formed on the outer surface of the shaft tube 2 by two-color molding. The shaft cylinder 2 may have a clip 21. Further, the cuticle 4 and the shaft cylinder 2 may be integrated.

  As shown in FIG. 7, the knock-type writing instrument 1 is further fixed to the rear portion in the shaft cylinder 2, and is disposed in the inner cylinder 6 that forms a part of the shaft cylinder 2, and the shaft A knock bar 7 that protrudes rearward from the cylinder 2, a rotor 8a that is disposed in the inner cylinder 6 and positioned in front of the knock bar 7, and a shaft 2 that is disposed in front of the rotor 8a. The ink storage tube 9 is in contact, the spring 10 is disposed in the cutlery 4 and urges the ink storage tube 9 backward, and the ball-point pen tip 11 is attached to the front end of the ink storage tube 9. The inner cylinder 6 may be integrated with the shaft cylinder 2.

  Hereinafter, with reference to FIG. 8, the structure and operation | movement of the knock mechanism for making a pen tip appear and disappear by knocking the rear-end part of a writing instrument (knock operation) are demonstrated.

  First, the structure 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 bar 7, and a rotor 8a. FIG. 8 is an enlarged exploded perspective view of the inner cylinder 6, the knock bar 7, and the rotor 8a.

  Four outer cams 61 are formed at equal intervals in the circumferential direction, as indicated by broken lines in FIG. Between the adjacent outer cams 61, four grooves 62 extending in the front-rear direction are formed. Each outer cam 61 includes three rod-like portions 611, 612, and 613 that extend in the front-rear direction and are continuously arranged in the circumferential direction. The second rod-shaped portion 612 disposed in the middle has a projection 71 of a knock rod 7 described later 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. In order to form a recess between the first rod-shaped portion 611 and the third rod-shaped portion 613 so as to be accommodated above the first rod-shaped portion 611 and the third rod-shaped portion 613. It has a thickness. In addition, since the inner cylinder 6 is being fixed to the axial cylinder 2, it does not move by knock 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 bar 7. Each protrusion 71 is moved 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. It is configured to slide in the direction. A cam surface 72 is formed at the front end of the knock bar 7. The cam surface 72 has eight peaks 721 and valleys 722. The rear end portion of the knock bar 7 engages with the knock cover 3. The knock cover 3 may be integrated with the knock bar 7.

  The rotor 8 a has an insertion portion 81 a that is inserted into the knock rod 7 for centering with 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 bar 7 is formed at the rear end of the cam portion 82a. Similar to the cam surface 72, the cam receiving surface 83 a has eight peak portions 831 a and valley portions 832 a. Four inner cams 84a extending in the front-rear direction are formed on the outer peripheral surface of the cam portion 82a 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 is engaged with the outer cam 61 in the front-rear direction or the engagement is released, and In the groove 62. When the inner cam 84a is accommodated in the groove 62 between the outer cams 61, the outer cam 61 is accommodated in the groove 85a between the inner cams 84a.

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

  In a state where the pen tip is immersed in the cutlery 4, the inner cam 84 a of the rotor 8 a is accommodated in the groove 62 between the outer cams 61 of the inner cylinder 6. When the knock bar 7 is advanced against the biasing force of the spring 10 from this state, the cam surface 72 of the knock bar 7 presses the cam receiving surface 83a of the rotor 8a, and the rotor 8a moves forward together with the knock bar 7. . At this time, the knock bar 7 and the rotor 8a receive axial and circumferential forces from each other via the cam surface 72 and the cam receiving surface 83a. Thereafter, when the rear end of the inner cam 84a exceeds the front end of the outer cam 61, the restriction in the circumferential direction of the rotor 8a is released, so that the rotor 8a is moved in the circumferential direction (counterclockwise as viewed from the front) by the circumferential force. Around). On the other hand, the knock bar 7 is not rotated in the circumferential direction because rotation in the circumferential direction is restricted by the protrusion 71 coming into contact with the outer cam 61.

  When the knock bar 7 is released in this state, the knock bar 7 and the rotor 8a are moved backward 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. Since the engagement prevents the rotor 8a from moving backward, the ball-point pen tip 11 attached to the ink containing tube 9 that contacts the rotor 8a protrudes from the cuticle 4.

  On the other hand, when the pen tip protrudes, 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 bar 7 is advanced from this state against the urging force of the spring 10, the cam surface 72 of the knock bar presses the cam receiving surface 83a of the rotor 8a, and the rotor 8a moves forward together with the knock bar. At this time, the knock bar 7 and the rotor 8a receive axial and circumferential forces from each other via the cam surface 72 and the cam receiving surface 83a. Thereafter, when the rear end of the inner cam 84a exceeds the front end of the outer cam 61, the restriction in the circumferential direction of the rotor 8a is released, so that the rotor 8a is moved in the circumferential direction (counterclockwise as viewed from the front) by the circumferential force. Around). On the other hand, the knock bar 7 is not rotated in the circumferential direction because rotation in the circumferential direction is restricted by the protrusion 71 coming into contact with the outer cam 61.

  When the knock bar 7 is released in this state, the knock bar 7 and the rotor 8 a are retracted by the urging force of the spring 10, and the inner cam 84 a rotated in the circumferential direction is accommodated in the groove 62 between the outer cams 61. At this time, since the ink containing tube 9 and the ballpoint pen tip 11 are also retracted by the urging force of the spring 10, the ballpoint pen tip 11 is immersed in the cutlery 4.

  Hereinafter, with reference to FIGS. 1-4, the shape of the rotor which concerns on embodiment of this invention is demonstrated.

  1A and 1B are respectively a rear perspective view and a front perspective view of a rotor 8b according to an embodiment of the present invention. 2A to 2C are a front view, a plan view, and a bottom view, respectively, of the rotor 8b of FIG. FIG. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 4 is a cross-sectional view taken along line BB in FIG.

  The rotor 8 b has an insertion portion 81 b that is inserted into the knock rod 7 for centering with the knock rod 7 and a cam portion 82 b 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 bar 7 is formed at the rear end of the cam portion 82b. Similar to the cam surface 72, the cam receiving surface 83 b has eight peak portions 831 b and valley portions 832 b. Four inner cams 84b extending in the front-rear direction are formed on the outer peripheral surface of the cam portion 82b at equal intervals in the circumferential direction. When the rotor 8b rotates in the circumferential direction when the cam surface 72 presses the cam receiving surface 83b, the inner cam 84b engages with the outer cam 61 in the front-rear direction or is disengaged from the outer cam 61. 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 FIGS. 1B and 3, the cam portion 82 b is thinned (stolen), and its inside is hollow. This can suppress the occurrence of sink marks during molding. On the other hand, although the insertion part 81b has a solid part, as shown in FIG. 10, it may be hollow over the entire front-rear direction.

  Four ribs 86 are formed at equal intervals in the circumferential direction inside the cam portion 82b. Each rib 86 protrudes radially inward and extends in the front-rear direction. The rib 86 has a shape that does not cause an undercut. The undercut means a convex or concave portion that is caught on the mold when the molded product is taken out from the mold.

  When the insertion portion 81b of the rotor 8b is to be inserted into the cam portion 82b of the other rotor 8b, the rear end of the insertion portion 81b collides with the front end of the rib 86. Therefore, the insertion portion 81b is connected to the cam portion 82b. The entry is hindered, and consequently the connection between the rotors 8b is prevented. FIG. 5 shows a state where the connection between the rotors 8b according to the embodiment of the present invention is prevented. By forming the rib 86 inside the cam portion 82b, the connection between the rotors 8b can be prevented while minimizing an increase in the thickness of the cam portion 82b.

  The inside of the cam portion 82b may have another shape as long as it can prevent the insertion portion 81b from entering without having an undercut. For example, the inner diameter of the cam portion 82b may be simply reduced without forming the rib 86 inside the cam portion 82b. In this case, the cross-sectional shape along the short direction inside the cam portion 82b is, for example, a circle or a polygon.

  As shown in FIG. 4, the circumferential position of the rib 86 is different from the circumferential position of the inner cam 84b. More specifically, the rib 86 is formed in the middle of two adjacent inner cams 84b in the circumferential direction, and is separated from the adjacent inner cams 84b by approximately 45 °. As a result, the thickness of the cam portion 82b can be made more uniform, and the occurrence of sink marks on the cam portion 82b during molding can be further suppressed while preventing the rotors 8b from being connected to each other.

  Further, as can be seen from FIG. 1B, the rib 86 is tapered forward, and a draft angle is formed. Thus, the rotor 8b can be easily taken out from the core pin of the mold disposed inside the cam portion 82b during molding.

  The preferred embodiments according to the present invention have been described above, but 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 writing instrument in which the pen tip appears and disappears by a knocking operation.

DESCRIPTION OF SYMBOLS 1 Knock type writing instrument 2 Shaft cylinder 21 Clip 3 Knock cover 4 Cutler 5 Grip rubber 6 Inner cylinder 61 Outer cam 611 1st rod-shaped part 612 2nd rod-shaped part 613 3rd rod-shaped part 62 Groove 7 Knock stick 71 Projection 72 Cam Surface 721 Mountain portion 722 Valley portion 8a, 8b Rotor 81a, 81b Insertion portion 82a, 82b Cam portion 83a, 83b Cam receiving surface 831a, 831b Mountain portion 832a, 832b Valley portion 84a, 84b Inner cam 85a, 85b Groove 86 Rib 9 Ink storage tube 10 Spring 11 Ballpoint pen tip

Claims (3)

An outer cam formed on the inner peripheral surface of the shaft tube;
A knock bar protruding rearward from the shaft tube and having a cam surface;
A rotor disposed within the shaft cylinder, the rotor including an insertion portion inserted into the knock rod, and a cam portion engaged with the knock rod; the cam portion including the cam surface; A cam receiving surface having a complementary shape and an inner cam are formed, and when the rotor rotates in the circumferential direction by the cam surface pressing the cam receiving surface, the inner cam In a knock type writing instrument comprising a knock mechanism composed of a rotor configured to engage or disengage in a direction,
The knock-type writing instrument, wherein the inside of the cam portion is hollow and has a shape that prevents the insertion portion from entering.   The knock type writing instrument according to claim 1, wherein a plurality of ribs protruding radially inward are formed inside the cam portion.   The knock type writing instrument according to claim 2, wherein a circumferential position of the rib is different from a circumferential position of the inner cam.

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