JP5954954B2 - mechanical pencil - Google Patents

Description

The present invention relates to a sharp pencil in which a holding chuck that provides resistance to the movement of the lead is disposed at the tip of a writing instrument for feeding out the lead.

Conventionally, NBR rubber has been mainly used as the material for holding pencils for mechanical pencils, but NBR rubber is inexpensive, but if the dimensions and hardness are not set properly, the holding chuck will be the leading member during long-term use. There was a case where it would come off. If the holding chuck is detached from the tip member, the holding chuck moves together with the lead during the lead feeding operation, and the lead feeding operation becomes impossible. Therefore, as disclosed in Patent Document 1, a technique is disclosed in which the core feeding operation is prevented from being disabled using a silicone rubber.

JP-A-10-016475

However, the types of silicone rubber described in Patent Document 1 are various. As a matter of course, some of the many silicone rubbers have good and bad compatibility with the core. An example of a bad one is one in which the resistance (holding) force to the core is significantly reduced. Specifically, there are a case where the hole through which the core of the holding chuck passes becomes large and a case where the surface of the hole passing through is hardened. When the hole becomes large or the surface of the hole is hardened, the resistance (holding) force to the core is lost, and the core (hereinafter referred to as the remaining core) removed from the chuck that grips the core rotates. There arises a problem that good writing cannot be performed.
In addition, since the holding chuck is elastically fitted into the base, the writing core may be broken and the holding chuck may come off when the writing core is inserted from the base side.
Further, since the whole body is formed of soft rubber, it is deformed when inserted into the base during assembly. If it is bent and inserted, there is a risk that lead-out will be poor.
Furthermore, if the holding chuck is the size of a conventional mechanical pencil, the total length is a very small part of several millimeters, so it is difficult to distinguish the front and rear direction, and the orientation during assembly is difficult to understand.

Accordingly, the present invention provides a mechanical pencil using a holding chuck that solves the above-described problems and does not impair the function of holding the lead and ensures assemblability.

Therefore, after intensive development, the following inventions have been realized.
A mechanical pencil having a holding chuck built in a base is characterized in that the holding chuck is made of two kinds of materials and is made of a rubber elastic material having different hardness.
The holding chuck includes a fitting portion that fits into the base and a holding portion that holds the core, and the fitting portion has higher hardness than the holding portion.
The rubber elastic material is preferably a thermosetting rubber.
It is desirable that the fitting portion and the holding portion are formed in different colors.

According to the above invention, since the holding chuck is difficult to be deformed in the base, even if the lead is replenished from the front end side, it is difficult to come off and the feeding failure can be prevented.
Further, when the holding chuck is inserted into the base, it does not come off during use, and the fitting portion and the holding portion are made of different colors, so that the front-rear direction can be easily identified and the assemblability is improved.
Further, since the fitting portion is made of hard rubber, the holding chuck is not tilted and assembled in the base, and damage due to bending of the writing core can be prevented.

1 is an overall view of a mechanical pencil in the present invention. It is an enlarged view of a mechanical pencil writing part. It is a component diagram of the holding chuck | zipper in a 1st Example. It is a component diagram of the holding chuck in the 2nd example. It is a component diagram of the conventional holding chuck.

  From this, the form for implementing this invention is demonstrated. In addition, it is not limited to the following Example. The writing core side is indicated as the front, and the other is indicated as the rear.

1 and 2 show an example of a mechanical pencil that is an embodiment of the present invention. FIG. 1 is a half sectional view of a mechanical pencil. FIG. 2 is an enlarged view of the front of FIG.
The shaft tube 7 is a tube body having a screw portion on the outer periphery of the front end portion, and a resin or metal base 1 is screwed into the screw portion, and the shaft tube 7 gripped at the time of writing. A grip 8 made of rubber or a thermoplastic elastomer is provided over the outer periphery of the front end and the rear outer periphery of the base 1.
The chuck 5 is disposed in the inner hole at the front end of the shaft cylinder 7 with the fastener 6 fitted on the outer periphery of the writing core gripping section at the front end, and the rear end of the chuck 5 is the shaft cylinder 7. A spring 9 is laid between the front step portion of the shaft tube and the step portion 4a provided on the rear outer peripheral portion as appropriate from the front end portion of the core case 10. The chuck 5 is biased toward the retracting side with respect to the shaft cylinder 7.

The base 1 has a tip pipe portion (a pipe that is integral with or separate from the base may be attached) through which the writing core 16 is inserted, and a holding chuck 2 that holds the writing core 16 in front of the inner diameter portion. The split ring 3 is fitted to the rear, and a step portion with which a front end of the split ring 3 abuts and a rear end of the split ring 3 are arranged so that the split ring 3 can be moved back and forth at a predetermined interval. The abutting stop ring 4 is fixed. (In the case of a resin-made mouth part, it can be formed as an integral protrusion.) Further, the fastener 6 moves back and forth within a range in contact with the rear end of the retaining ring 4 of the base 1. The interval is a main factor for determining the feeding amount of the writing core 16. (If there is no stop ring, a stepped part is formed.)

Further, a damper spring 12 is provided between a protrusion provided on the outer periphery of the front end of the lead case 10 and an inner stage of the slide cylinder 11 fitted on the outer periphery of the lead case 10 from the front end thereof. The rear end of the slide cylinder 11 is locked to the protruding portion of the core case 10 in a state where the is ejected. The slide cylinder 11 is a cylinder having an inner stage at the front end of the inner hole, and a slit portion opened at the rear end is formed on the side of the cylinder. The slit portion is formed with a taper portion that narrows toward the front end portion, a step portion is formed at the front end portion of the taper portion, and the front end portion is blocked at the front end portion of the step portion. A rectangular hole is formed. Moreover, although the slit part is provided in two places on balance, it may be one place or three places. Further, the protrusion provided on the core case 10 has a shape to be inserted into the slit portion, the protrusion elastically expands the tapered portion, and the protrusion is locked to the front surface of the stepped portion, The slide cylinder 11 can be retracted with respect to the core case 10 at an interval at which the protrusion comes into contact with the front end of the hole. The means for locking the slide cylinder to the writing core 16 case is not limited to the above embodiment.

Further, an eraser mounting base is integrally provided at the rear end of the core case 10, and an eraser 14 is fixed to the inner hole portion thereof, and a knock cover 13 having a decorative part 15 attached to the rear end portion is fitted to the outer peripheral portion. It is worn and its rear end is a knock.

The chuck 5 holds the writing core 16 when engaged with the fastener 6, knocks the rear end of the knock cover 13, and the fastener 6 advances together with the chuck 5. The writing core 16 also advances until it abuts on the rear end and is prevented from moving forward. Further, the gripping of the writing core 16 is released by releasing the tightening of the chuck 5. The writing core 16 is gradually drawn out by repeating the above-described knock forward and reverse by knock release.

Further, when the tip of the chuck 5 is engaged with the split ring 3 in the tip portion provided at the front end of the shaft cylinder 7 by moving the chuck 5 forward, the writing core 16 is gripped. The writing core 16 which protrudes from the front-end | tip of the front-end | tip pipe of the nozzle | cap | die 1 by being maintained and retracted is accommodated. Further, immediately before the front end of the chuck 5 is engaged with the split ring 3, the front end of the slide cylinder 11 that has advanced with the core case 10 abuts on the rear stage provided on the shaft cylinder 7, and the advance is prevented. Since the damper spring 12 is compressed (damper is actuated) and the knocking force is rapidly increased, the difference between the knocking operation when the writing core 16 is extended and the knocking operation when the writing core 16 is accommodated can be easily grasped.

FIG. 3 shows a first embodiment of the holding chuck 2 according to the present invention. FIG. 3A is a side view. FIG. 3B is a longitudinal sectional view of FIG. The holding chuck 2 includes a fitting portion 21 that is press-fitted into the inner surface of the base 1 and a holding portion 22 that sandwiches the writing core 16. The fitting part 21 is formed behind the holding part 22, and an adhesive surface 23 is interposed between the front end face of the fitting part 21 and the rear end face of the holding part 22.
The material of the fitting part 21 and the holding part 22 is both thermosetting rubber and different two kinds of materials, so that the holding chuck is easy to manufacture and does not have a problem even if the dimensional tolerance is larger than that of the hard material. be able to. The material of the fitting portion 21 is desirably a hard rubber such as NBR, EPDM, fluororubber, silicone rubber, etc., which has a durometer A hardness of 90 or more or a durometer D hardness of 35 or more in accordance with JIS K6253. Or in order to raise hardness, it is good also as what is based on resin, glass, and a mixture with carbon fiber, such as polyester series. The material of the holding part 22 is preferably a soft rubber having a durometer A hardness of 70 or less, such as NBR, EPDM, fluorine rubber, silicone rubber, or the like. If the fitting portion 21 and the holding portion 22 are colored differently, it becomes easy to identify the front and rear directions, so that it is possible to prevent erroneous insertion into the base during assembly. The adhesive surface 23 can form the holding chuck 2 by adhesion with a rubber adhesive or integral molding by a biaxial injection molding machine or compression molding.

  In the outer diameter portion of the holding chuck 2, the fitting portion 21 has a press-fit surface 24 in which the fitting portion 21 and the base 1 are fitted, and the holding portion 22 in front of the press-fit surface 24 has a step inside the base 1. A step portion 25 is formed in contact with the portion to prevent unnecessary movement of the holding chuck 2 forward. In the inner diameter portion, the holding portion 22 is formed with a holding surface 26 for holding the writing core 16, and a taper portion 27 for guiding the writing core 16 to the holding surface 26 is fitted to the holding portion 22 at the rear of the holding surface 26. The joint portion 21 is formed together.

  FIG. 4 shows a second embodiment of the holding chuck according to the present invention. FIG. 4A is a side view. FIG. 4B is a longitudinal sectional view of FIG. The difference from the first embodiment is that the stepped portion 25 is formed in the fitting portion 21 and is concave when viewed from the cross section, and the holding portion 22 is inserted into the recess. By adopting this shape, the area of the contact surface 23 between the fitting portion 21 and the holding portion 22 is larger than that of the first embodiment, and the shape is difficult to separate. Further, since the area of the press-fitting surface 24 is increased, the stability of the fitting force with the base 1 due to manufacturing variations can be suppressed.

  FIG. 5 shows a conventional holding chuck. The fitting part 21 and the holding part 22 are formed of the same material.

  As described above, according to the present invention, since the fitting portion and the holding portion are formed in the holding chuck made of different rubber elastic materials, it is difficult to come off from the base and the feeding failure can be prevented, and the writing core is bent by preventing the assembly failure. It is an industrially useful invention that can prevent damage caused by the above.

DESCRIPTION OF SYMBOLS 1 Base 2 Holding chuck 3 Split ring 4 Stop ring 5 Chuck 6 Fastener 7 Shaft cylinder 8 Grip 9 Spring 10 Core case 11 Slide cylinder 12 Damper spring 13 Knock cover 14 Eraser 15 Decoration part 16 Writing core 21 Fitting part 22 Holding portion 23 Adhesive surface 24 Press-fit surface 25 Step portion 26 Nipping surface 27 Tapered surface

Claims (3)

In a mechanical pencil equipped with a holding chuck built in the base, the holding chuck is made of a rubber elastic material made of two kinds of materials and having different hardness, and a holding part that holds the core and a fitting part that fits the base. The mechanical pencil is characterized in that the fitting portion is harder than the holding portion . The mechanical pencil according to claim 1, wherein the rubber elastic material is a thermosetting rubber. The mechanical pencil according to claim 2, wherein the fitting portion and the holding portion are formed in different colors.

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