JP2001071678A - Push-button type mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate laterally running-out of a clamp either to a mouth piece or to a barrel, surely realize the press-connection between a chuck and a lead tank and, at the same time, improve the following-up property of a lead. SOLUTION: The rear part 7H of a chuck 7 is press-connected with the front part inner hole 8B of a lead tank 8 in a barrel 1. Further, between the inner step 2A of a mouthpiece 2 and the barrel 1, the outer flange 6A of a clamp 6 is loosely fitted so as to be properly gliding longitudinally. The font part 6B of the clamp 6 is inserted in the inner aperture 2B of the mouthpiece 2 so as to be gliding longitudinally. Further, the rear part 6C of the clamp 6 is inserted in the front inner aperture 1A of the barrel 1 so as to be gliding longitudinally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knock mechanical pencil for feeding a lead by moving a chuck forward.

[0002]

2. Description of the Related Art A conventional knock-type mechanical pencil inserts a fastener into an inner hole of a base so as to be slidable in a longitudinal direction.
The rear part of the fastener is inserted slidably in the longitudinal direction into the front inner hole of the barrel.

[0003]

Therefore, when a fastener is inserted into the inner hole of the base, the chuck with the fastener externally sways in the shaft cylinder, and the chuck and the core tank are press-fitted. Sometimes, the axis of the chuck and the axis of the core tank are shifted, and the chuck may be bent and attached.

In the case where the rear part of the fastener is inserted into the front inner hole of the shaft cylinder, the fastener oscillates in the inner hole of the base, and the core held by the chuck is used for the core holder of the base. There is a problem that the wick cannot pass and the wick cannot follow.

An object of the present invention is to provide a knock mechanical pencil that solves the above-mentioned problems.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a knock type mechanical pencil that feeds out a lead by advancing a chuck, in which a chuck is inserted from the front of a barrel and a lead tank is inserted from the back of the barrel. In the barrel, the rear part of the chuck is press-fitted to the front bore of the core tank, and the outer flange of the fastener is loosely fitted between the inner part of the base and the barrel so as to be slidable in the longitudinal direction. The front part of the fastener is slidably inserted in the inner hole of the base in the longitudinal direction, and the rear part of the fastener is slidably inserted in the front inner hole of the barrel.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A knock mechanical pencil according to the present invention will be described below with reference to FIG. The left side of the drawing is the front and the right side is the back. A synthetic resin base 2 is detachably screwed to a front portion of the barrel 1, and a rubber core holder 4 for holding the core 3 with an appropriate force is built in the base 2. Further, a guide pipe 5 made of stainless steel is fixed to the end of the base 2.

An outer flange 6A of a fastener 6 is loosely fitted between the inner step 2A of the base 2 and the front end of the barrel 1 so as to be slidable in the longitudinal direction as needed. It is slidably inserted into the inner hole 2B in the longitudinal direction. The rear part 6C of the fastener 6 is inserted into the front inner hole 1A of the barrel 1 so as to be slidable in the longitudinal direction.

Therefore, the rear part 6C of the fastener 6 has the barrel 1
Is guided by the front inner hole 1A and the front portion 6B is guided by the inner hole 2B of the base 2, so that the lateral run-out of the base 2 is also restricted.

A chuck 7 for externally fitting the fastener 6 to the head.
Is made of synthetic resin, and as shown in FIGS. 2 and 3, an elastic piece 7A is formed by being divided from the front end, and a head formed at the front of the elastic piece 7A is shown in FIG. As described above, the substantially semicircular maximum diameter portion 7C formed at the tip of the core holding portion 7B and the raised portion 7D formed at the top outside the core holding portion 7B as shown in FIGS. Be composed. The radius of curvature of the maximum diameter portion 7C is formed slightly smaller than the radius of curvature of the sliding hole 2C of the base 2 and larger than the radius of curvature of the inner hole 6D of the fastener 6. Further, the protruding portion 7D of the chuck 7 is formed so as to gradually increase as it goes forward in the longitudinal direction, and the cross-sectional shape of the protruding portion 7D is formed in a semicircle with both sides cut, and its outer peripheral surface 7E
Is formed slightly larger than the inner hole 6D of the fastener 6. In addition, the raised portion 7D has the same radius of curvature at any position in the longitudinal direction.

As shown in FIG. 7, an inner hole 7F located inside the elastic piece 7A of the chuck 7 has a core holding portion 7B.
Are formed in a tapered shape gradually narrowing toward the front in the longitudinal direction.

The shape of the core holding portion 7B of the chuck 7 is preferably substantially the same as the shape of the core 3 to be held. As shown in FIG. 8, when the chuck 7 is closed, the elastic piece 7A bends in a mountain shape. If the elastic holding member 7B is configured to be inclined so as to widen as it goes forward, the elastic piece 7A exactly matches the core 3 when the elastic piece 7A is bent, and the core 3 can be securely held. it can.

Although not shown, the shaft cylinder 1 and the core tank 8 are not shown.
A spring is stretched between them, and the lead tank 8 is normally urged rearward in the longitudinal direction. Therefore, the raised portion 7D of the chuck 7 comes into contact with the front end of the inner hole 6D of the fastener 6. At this time, since the radius of curvature of the raised portion 7D of the chuck 7 is formed larger than the radius of curvature of the inner hole 6D of the fastener 6, FIG.
As shown in the figure, the fastener 6 is fixed at two points on both sides 7G of the raised portion 7D.
, And prevents the chuck 7 located in the fastener 6 from swaying.

FIG. 10 shows a cylindrical rear portion 7H of the chuck 7.
As shown in (1), an outer flange portion 7I cut on both sides is formed, and two ridge portions 7J are further formed behind the outer flange portion 7I. The ridge 7J has a front end formed vertically and a rear end formed to be inclined. The reason for cutting both sides of the rear part 7H is to provide a gate in this part.

In the method of press-fitting and connecting the chuck 7 to the core tank 8, the rear part 7H of the chuck 7 is first inserted into the inner hole 6D of the fastener 6, and the fastener 6 is fitted on the head of the chuck 7. Further, a ridge 7J formed on a rear portion 7H of the chuck 7 is provided.
Is first inserted into the guide hole 8A of the core tank 8 formed to have a diameter larger than the outer diameter of the ridge 7J, so that the axis of the chuck 7 and the axis of the core tank 8 are substantially aligned. Next, the rear part 7H of the chuck 7 is press-fitted into the front inner hole 8B of the core tank 8 formed thicker than the outer periphery 7K of the rear end of the chuck 7 and thinner than the ridge 7J to form the front inner hole 8B of the core tank 8. Two concave grooves 8
The protrusion 7J of the chuck 7 is fitted into each of C, and the chuck 7 and the core tank 8 are press-fitted and connected.

From the difference between the radius of the guide hole 8A of the core tank 8 and the radius of the front inner hole 8B of the core tank 8, the difference between the radius of the ridge 7J of the chuck 7 and the radius of the rear end outer periphery 7K of the chuck 7 is obtained. When the protrusion 7J of the chuck 7 is inserted into the guide hole 8A of the core tank 8, the rear end of the chuck 7 is inevitably inserted into the front inner hole 8B of the core tank 8. The chuck 7 can be automatically inserted without aligning the rear end with the front inner hole 8B of the core tank 8.

The chuck 7 is made of polyacetal with glass fibers inserted therein, and is formed by injection molding. The molded product is molded with the chuck 7 expanded.

Further, since the radius of curvature of the maximum diameter portion 7C of the chuck 7 is formed slightly smaller than the radius of curvature of the sliding hole 2C of the base 2, the sliding hole of the base 2 when the chuck 7 is expanded. Since the axis is coincident with 2C and the core holding portion 7B of the chuck 7 is located at the center, the core 3 in the core tank 8 can surely fall in the core holding portion 7B of the chuck 7.

In addition, the radius of curvature of the maximum diameter portion 7C of the chuck 7 is formed larger than the radius of curvature of the inner hole 6D of the fastener 6, and the width of the maximum diameter portion 7C is larger than the diameter of the inner hole 6D of the fastener 6. Since the chuck 7 is formed large, the head of the chuck 7 is pressed by the fastener 6 by the spring, and there is no possibility that the head of the chuck 7 comes out of the fastener 6 even when the chuck 7 is closed.

Further, as described above, the outer peripheral surface 7E of the raised portion 7D formed on the head of the chuck 7 has the same radius of curvature at any position in the longitudinal direction, so that the outer surface 7E is Even if the position of the fastener 6 abutting on the raised portion 7D of the chuck 7 shifts back and forth due to the variation in diameter, the chuck 7 and the fastener 6 always abut in the same state. That is,
As shown in FIG. 9, even if the position of the fastener 6 is shifted back and forth, the fastener 6 always closes at the front end of the inner hole 6 </ b> D at two points on both sides 7 </ b> G of the raised portion 7 </ b> D and is closed by the fastener 6. Chuck 7
Is always in a state in which the fastener 6 and the axis coincide with each other without lateral deflection.

FIGS. 11 and 12 show another embodiment of the present invention. The same members as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. A plurality of ribs 12D extending in the longitudinal direction are formed in the inner hole 12B of the base 12 at equal intervals in the circumferential direction, and the fastener 6 between the inner step 12A formed at the rear end of the rib 12D and the front end of the barrel 1 is formed. The outer flange 6A is freely slidably fitted in the longitudinal direction, and the front portion 6B of the fastener 6 is inserted inside the rib 12D so as to be slidable in the longitudinal direction.

As described above, when the front portion 6B of the fastener 6 is guided by the rib 12D, the possibility of contact with the fastener 6 is reduced even if the inner hole 12B of the base 12 has a dimensional variation.
The fastener 6 slides reliably. Further, when the base 12 is injection-molded with a synthetic resin, there is no danger that the inner hole 12B will be dented.

Although the above embodiment has been described with reference to a chuck made of a synthetic resin, the present invention can sufficiently achieve the intended effects even with a metal chuck.

[0024]

In the above-described knock mechanical pencil according to the present invention, since the fastener is guided by the inner hole of the base and the front inner hole of the barrel, the fastener can be attached to both the base and the barrel. It is possible to surely press-fit and connect the chuck and the lead tank without lateral deflection, and to improve the followability of the lead.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a knock mechanical pencil according to the present invention.

FIG. 2 is a front view showing a chuck in the knock mechanical pencil of the present invention.

FIG. 3 is a plan view showing a chuck in the knock mechanical pencil of the present invention.

FIG. 4 is an end view showing a front end of a chuck in the knock mechanical pencil of the present invention.

FIG. 5 is a sectional view taken along line AA in FIG. 2;

FIG. 6 is a sectional view taken along line BB in FIG. 2;

FIG. 7 is a bottom view of a main part showing the inside of the front part of the elastic piece in the chuck.

FIG. 8 is a cross-sectional view showing a state where the chuck is closed to hold the core.

FIG. 9 shows a knock mechanical pencil according to the present invention.
It is sectional drawing which shows the state which the front end of the fastener contacted the protrusion part of the chuck.

FIG. 10 is a sectional view taken along line CC in FIG. 2;

FIG. 11 is a sectional view of a main part showing another embodiment of a knock mechanical pencil according to the present invention.

FIG. 12 is a sectional view taken along line AA of FIG. 11;

[Explanation of symbols]

 Reference Signs List 1 Shaft tube 1A Front inner hole of shaft tube 1 2 Base 2B Inner hole of base 3 3 Core 6 Fastener 6A Outer flange of fastener 6 6B Front of fastener 6C Rear of fastener 6 Chuck 7H Chuck 7 Rear 8 Core tank 8B Front inner hole of core tank 8 12 Base 12D Rib of base 12

Claims (2)

[Claims] 1. A knock type mechanical pencil which feeds a lead by advancing a chuck, inserts the chuck from the front of the barrel, inserts a lead tank from the back of the barrel, and inserts the rear part of the chuck in the barrel. While press-fitting and connecting to the front inner hole of the core tank, the outer flange of the fastener is loosely fitted between the inner stage of the base and the barrel so as to be slidable in the longitudinal direction as appropriate, and the front of the fastener is connected to the base of the base. A knock type mechanical pencil characterized in that it is slidably inserted in an inner hole in a longitudinal direction, and a rear portion of a fastener is slidably inserted in a longitudinal direction in a front inner hole of a barrel. 2. The device according to claim 1, wherein ribs extending in the longitudinal direction are formed in the inner hole of the base at equal intervals in the circumferential direction, and the ribs restrict lateral deflection of the front part of the fastener. Knock mechanical pencil.