JPH1142886A - Lead holder of mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead holder of a mechanical pencil wherein the tip of a front part of a casing is made integral to a lead return stopper. SOLUTION: In the medianical pencil, a lead propelling mechanism is disposed in a casing, and a tip part 6 is provided at the forward end of the casing and a lead return stopper 7 is disposed in the part 6. And the tip part 6 is made integral to the stopper 7 which is formed from two opposed pieces, and the stopper 7 consists of a first cone part 19 for guiding a lead, a straight part 20, a second cone part 21, a contracted diameter part 22 for substantially holding the lead, a third cone part 23 having a surface inclined in the opposite direction to the first cone part, and an expanded diameter part 24 having a diameter approximately equal to that of the straight part, and these parts are formed continuously in that order.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a core feeding mechanism disposed inside a barrel, and a tip provided at a front part of the barrel.
The present invention relates to a sharp pencil having a center detent disposed in a tip portion thereof.

[0002]

2. Description of the Related Art As an example, there is Japanese Utility Model Application Laid-Open No. Sho 61-70077. The claims for the utility model registration include: a cylindrical portion extending in the required length axial direction behind the front end opening inside the hole, and a central portion of the cylindrical portion from a required position on the inner peripheral surface of the cylindrical portion. The required number of elastic projections, which are set to be slightly smaller than the core diameter, are formed integrally with the main body part, and the imaginary inscribed circle projecting while projecting forward toward the front and connecting its tip end surface is slightly smaller than the core diameter. Tip parts such as a mouthpiece, a tip shaft and the like having a tip core holding part in a sharp pencil. "
That is, the core is held by the inclined elastic projection.

[0003]

Generally, the above-mentioned base, tip shaft and the like are formed (formed) by injection molding.
Then, a member called a core pin (one member of a mold) is used to form a space portion and the elastic projection inside the die. However, in the above prior art, since the elastic projections project toward the center of the tubular portion while being inclined forward, in other words, since the elastic projections are barbed, after the molding is completed, When the core pin is to be pulled out of the molded product (base), the elastic projection and the concave portion of the core pin forming the elastic projection are engaged with each other. In some cases, the molded product was deformed even if it could not be torn. Here, it is conceivable to solve the above problems by complicating the shape and structure of the core pin of a mold to be injection-molded and one part thereof.
The manufacturing cost of the mold is high, and if necessary, the price of the product will rise.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a core feeding mechanism disposed in a shaft cylinder, and a tip portion provided at a front portion of the shaft cylinder. What is claimed is: 1. A sharp pencil having a center detent disposed in a tip portion thereof, wherein the tip portion and the center detent are integrally formed, and the center detent is constituted by two opposing pieces. A first conical portion for guiding the wick, a straight portion, and a second conical portion;
A reduced diameter portion for substantially holding the core, a third conical portion having an inclined surface opposite to the first conical portion, and an enlarged diameter portion having substantially the same diameter as the straight portion; The gist is that they are formed continuously in order.

[0005]

The enlarged diameter portion has a larger diameter than the reduced diameter portion, but the third conical portion allows the core pin of the mold to easily escape rearward (upward) from the molded product (tip).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first example will be described with reference to FIGS. Inside a barrel 1 made of a transparent or colored translucent material, a lead tank 2 for storing a plurality of leads is arranged so as to be able to move back and forth. A chuck body 3 for holding and releasing the core is fixed in front of the core tank 2, and a chuck ring 4 for closing and expanding the chuck body 3 is surrounded in an intermediate portion of the chuck body 3. It is attached in the state where it was set. Also,
A resilient member (chuck spring) 5 such as a coil spring is stretched between the barrel 1 and the core tank 2 to urge the core tank 2 and the chuck body 3 rearward. Reference numeral 6 denotes a tip member which is detachably attached to the front end of the barrel 1 by screwing or the like, and is made of a transparent or colored translucent material like the barrel 1, and is provided inside the tip member 6. Is formed integrally with a center detent portion 7 for preventing the core from retreating. Here, the center detent portion 7 is also made of a transparent or colored translucent material.

The rear of the core tank 2 protrudes from the rear end portion 8 of the barrel 1, and an eraser 10 is press-fitted into the inside of the protruding portion (protruding portion 9) in a detachable manner.
A knock member 11 for pressing the lead tank 2 is detachably press-fitted into the protruding portion 9 of the lead tank 2. Hereinafter, the knock member 11 will be described in detail. Behind the inner surface of the knock member 11, a short vertical rib 12 having a small inscribed diameter is provided.
And long longitudinal ribs 13 having a large inscribed diameter are formed alternately and radially. The inscribed diameter of the long vertical rib 13 having a large inscribed diameter is substantially the same as the outer diameter of the core tank 2. That is, the knock member 11 is detachably press-fitted into the protruding portion 9 of the core tank 2 by the long vertical rib 13.

Here, the front end of the short vertical rib 12 is in contact with the rear end of the core tank 2 to regulate the insertion position into the core tank 2. Further, the front end of the long vertical rib 13 can be brought into contact with the rear end 8 of the shaft cylinder 1 when the knock member 11 is pressed and the lead-out operation is performed. Then, at the time of the contact, the chuck spring 5 does not completely adhere, and for example,
The chuck ring has a contraction range that allows the chuck ring to come off the chuck body and release the core. The outer peripheral cylinder portion 14 of the knock member 11 is formed up to a position covering the rear portion of the shaft cylinder 1, and is more like a cap than a knock member, and has an aesthetic appearance as a sharp pencil. In addition, the rear portion of the barrel is used as a guide to prevent the wobble (wobble) caused by the pressing operation of the knock member. . The cross-sectional shape of the short vertical ribs 12 is different from the cross-sectional shape of the long vertical ribs 13. By making the cross-sectional shape of the short vertical rib 12 substantially square, the contact area with the rear end of the core tank is increased. This is where pressure is applied when the centering operation is performed, preventing damage to the vertical ribs. Reference numeral 15 denotes a clip integrally formed with the knock member 11, but the clip 15 may be formed as a separate member and fixed to the knock member.

Next, the tip member 6 will be described in detail. A center detent portion 7 is formed inside the tip member 6, and the center detent portion 7 includes two opposing pieces 16,
17. The pieces 16, 17
A core holding portion 18 is provided on the inner surface of the core
The lead holding portion 18 has a first conical portion 19 for guiding the tip of the lead when the first lead is fed from above (in the drawing), a straight portion 20 for positioning the lead, Subsequently, a reduced diameter portion 22 for substantially holding the core is formed via a second conical portion 21 for gradually holding the core along the conical portion. In addition, below the reduced diameter portion 22, via a third conical portion 23 that reverses the direction of inclination with respect to the first conical portion, an enlarged diameter portion 24 having substantially the same diameter as the straight portion 20. Are formed. That is, the reduced diameter portion 2
2 are located above and below the reduced diameter portion 22.
The second and third conical portions are formed continuously so as to form an obtuse angle with 0 or the enlarged diameter portion 24. The formation of the third conical portion 23 facilitates the removal of the core pin of the mold from the molded product during molding.

Reference numeral 25 denotes a rib formed on the inner surface of the tip member 6. The rib 25 is formed by arranging an outer core pin outside the core pin forming the core holding portion 18 but inside the screw core pin. ing. After the outer core pin comes off from the core holding portion 18, the core pin forming the inner surface of the core holding portion 18 comes off from the molded product (the inner surface of the core holding portion). It is possible to escape in the outward direction, and in addition to the above-described effects, the mold releasability between the molded product and the core pin is further facilitated. In addition, the ribs 24 prevent the molded product (tip member) from rotating due to the screw core pin generated at the time of molding,
In addition, by forming the ribs, the strength of the molded article can be increased, and the molded article can be formed thin,
It is possible to prevent sink marks (dents) from occurring in the appearance.

Next, one example of the shaft cylinder made of the transparent or colored translucent material and the material of the tip member will be described. As the material of the barrel, ABS resin, AS resin and PC resin are generally used, but a transparent grade of these materials may be used as the material of the barrel and the tip member. However, since the lead holding member is formed integrally with the tip member, a material having high bending elastic modulus and good creep resistance (for example, P
It is more preferable to select (C resin) because it increases design, design, and flexibility. The tip and the barrel may be integrally formed, or a metal core protection pipe may be attached to the tip of the tip. Further, as shown in FIG. The core may be molded integrally with the core protection pipe portion so that the core can be checked.

[0012]

According to the present invention, there is provided a sharp pencil in which a core feeding mechanism is arranged in a barrel, a tip portion is provided in a front portion of the barrel, and a center detent is arranged in the tip portion. hand,
A first conical portion for guiding the core, wherein the tip and the detent are integrally formed, and the detent is constituted by two opposing pieces; A straight portion, a second conical portion, a reduced diameter portion for substantially holding the core, a third conical portion having an inclined surface in a direction opposite to the first conical portion, and substantially the same as the straight portion. Since it is composed of an enlarged diameter portion having the same diameter and is formed continuously in order, the tip member can be molded with a simple mold structure, and the tip member is not deformed. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first example of the present invention.

FIG. 2 is a longitudinal sectional view showing a knock member of the present invention.

FIG. 3 is a bottom view of the knock member of the present invention.

FIG. 4 is a longitudinal sectional view showing a tip member of the present invention.

FIG. 5 is an enlarged view of a main part of FIG. 4;

FIG. 6 is a sectional view taken along line AA of FIG. 4;

[Explanation of symbols]

 Reference Signs List 1 shaft cylinder 2 core tank 3 chuck body 4 chuck ring 5 chuck spring 6 tip member 7 core detent section 8 rear end 9 projecting section 10 eraser 11 knock member 12 short vertical rib 13 long vertical rib 14 outer peripheral cylinder 15 clip 16 Piece 17 piece 18 core holding portion 19 first conical portion 20 straight portion 21 second conical portion 22 reduced diameter portion 23 third conical portion 24 enlarged diameter portion 25 rib 26 core protection pipe

Claims (1)

[Claims] 1. A sharp pencil having a shaft feeding mechanism disposed in a shaft cylinder, a front portion provided in a front portion of the shaft tube, and a center detent disposed in the front portion. A first conical portion that guides the core, the core and the detent are integrally formed, and the detent is formed by two opposing pieces; and the detent formed by the two pieces is guided by the core. A straight portion, a second conical portion, a reduced diameter portion for substantially holding the core, a third conical portion having an inclined surface in a direction opposite to the first conical portion, and substantially the same diameter as the straight portion. A core holding portion of a sharp pencil, wherein the core holding portion is formed continuously in order.