JP2001047788A - Mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically introduce a rear end of a chuck into a front inner hole of a lead tank and to facilitate coupling of the chuck to the tank by increasing a difference between a radius of a protruding strip of the chuck and a radius of an outer periphery of the rear end of the chuck to larger than a difference between a radius of a guide hole of the tank and a radius of the front part inner hole of the tank. SOLUTION: A guide hole 8A is formed at a front part of a lead tank 8, and a front part inner hole 8B of smaller diameter than that of the hole 8A is formed. Two grooves 8C are formed in the hole 8B of the tank 8, and are formed in substantially the same shape as that of a protruding strip 11 of a chuck 1. The radius of the hole 8A disposed at a front end of the tank 8 is formed larger than that of the strip 11 formed at a rear part 1 of the chuck 1, and the radius of the strip 11 of the chuck 1 is formed larger than that of an outer periphery 1J of the rear end of the chuck 1. Further, a difference between the radius of the strip 11 of the chuck 1 and the radius of the outer periphery 1J of the rear end of the chuck 1 is increased larger than that between the radius of the hole 8A and the radius of the hole 8B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical pencil for press-fitting a rear portion of a chuck into a front inner hole of a core tank.

[0002]

2. Description of the Related Art In a conventional mechanical pencil, the rear end of a chuck is aligned with a front inner hole of a lead tank by press fitting.

[0003]

Therefore, the rear end of the chuck comes into contact with the front end of the core tank, and it is very troublesome to align the rear end of the chuck with the front inner hole of the core tank.

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

[0005]

According to the present invention, a chuck is inserted from the front of a barrel and a core tank is inserted from the back of the barrel, and a rear portion of the chuck is pressed into a front inner hole of the core tank in the barrel. In the mechanical pencil to be connected, the radius of the guide hole located at the front end of the lead tank is formed larger than the radius of the ridge formed at the rear of the chuck, and the radius of the ridge of the chuck is set to the radius of the outer periphery of the rear end of the chuck. The difference between the radius of the ridge of the chuck and the radius of the outer periphery of the rear end of the chuck is set to be larger than the difference between the radius of the guide hole of the core tank and the radius of the front inner hole of the core tank. is there.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mechanical pencil according to the present invention will be described below with reference to the drawings. In the drawing of the mechanical pencil shown in FIG. 1, the left side is the front and the right side is the back.

The chuck 1 made of synthetic resin is shown in FIGS.
As shown in FIG. 4, the elastic piece 1A is formed by dividing the front end into two parts, and the head formed at the front part of the elastic piece 1A is formed at the tip of the core holding part 1B as shown in FIG. As shown in FIG. 5 and FIG. 6, a substantially semicircular maximum diameter portion 1C and a raised portion 1D formed on the top outside the core holding portion 1B. The radius of curvature of the maximum diameter portion 1C is formed slightly smaller than the radius of curvature of the sliding hole 2A of the base 2 and larger than the radius of curvature of the inner hole 3A of the fastener 3. Further, the protrusion 1D of the chuck 1 is formed so as to gradually increase as it goes forward in the longitudinal direction, and the protrusion 1D
Is formed in a semicircle with both sides cut, and the radius of curvature of the outer peripheral surface 1E is formed slightly larger than the inner hole 3A of the fastener 3. In addition, the raised portion 1D has the same radius of curvature at any position in the longitudinal direction.

Further, as shown in FIG. 7, an inner hole 1F located inside the elastic piece 1A of the chuck 1 has a core holding portion 1B.
Is formed in a tapered shape gradually narrowing forward in the longitudinal direction, so that even if the chuck 1 is expanded, the inner hole 1F does not become unnecessarily large, and the inner hole 1F of the chuck 1 The core 4 that has fallen off the center of the inner hole 1F can no longer be followed, or the core 4
There is no fear that the object will be pinched.

Further, the shape of the core holding portion 1B of the chuck 1 is preferably substantially the same as the shape of the core 4 to be held.

Further, as shown in FIG. 8, an outer flange portion 1 having both sides cut is provided on a cylindrical rear portion 1G of the chuck 1.
H is formed, and two ridges 1I are further formed behind the H. The protruding ridge 1I has a front end formed vertically and a rear end inclined. The reason why both sides of the rear part 1G are cut is to provide a gate in this part.

Next, the configuration of the entire mechanical pencil of the present invention will be described with reference to FIGS. The crown 5 has a clip 6 integrally formed on the upper side and a small-diameter portion 5 on the front.
Form A. A protrusion 5B is formed on the outer peripheral surface of the small-diameter portion 5A immediately below the clip 6, and a protrusion 5C extending in the longitudinal direction is formed on the outer peripheral surface opposite to the protrusion 5B. Further, opening windows 5D extending in the longitudinal direction are formed on both sides of the small-diameter portion 5A so as to face each other, and the small-diameter portion 5A where the protrusion 5B is located is configured to be elastically deformable as appropriate.

The crown 5 has a smaller diameter portion 5 than the rear end of the barrel 7.
A is inserted, and the projection 5C of the crown 5 is fitted into the keyway 7A of the barrel 7. Furthermore, when the small diameter portion 5A of the crown 5 is inserted, the projection 5C of the crown 5 is fitted into the locking window 7B of the barrel 7, and the crown 5 is fixed to the barrel 7.

The core tank 8 has a guide hole 8A formed in the front part and a front inner hole 8B having a diameter smaller than that of the guide hole 8A.
Is formed. Further, the front inner hole 8B of the core tank 8 has 2 holes.
The two grooves 8C are formed, and the grooves 8C
Is formed in substantially the same shape as the ridge portion 1I. Further, as shown in FIG. 11, the guide hole 8 located at the front end of the lead tank 8 is provided.
A ridge 1I formed at the rear 1G of the chuck 1 with a radius of A
, The radius of the ridge portion 1I of the chuck 1 is formed larger than the radius of the outer periphery 1J of the rear end of the chuck 1, and the radius of the guide hole 8A of the core tank 8 and the inside of the front portion of the core tank 8 are adjusted. The difference L2 between the radius of the ridge 1I of the chuck 1 and the radius of the outer periphery 1J of the rear end of the chuck 1 is configured to be larger than the difference L1 in the radius of the hole 8B. A spare core 4 is stored in the core tank 8, and four projections 8 are provided at equal intervals in a circumferential direction at a rear portion of the core tank 8 for fixing a spring 9.
D and a spring 9 behind the projection 8D.
An outer step 8E is formed for abutting the contact. Furthermore, an eraser 10 is attached to the rear inner side 8F of the core tank 8,
A knob 11 that covers the eraser 10 is fitted to the rear outside 8G of the core tank 8.

A spring 9 is fitted from the front of the core tank 8 provided with the eraser 10 and the knob 11, and the rear part of the spring 9 is press-fitted and fixed to the projection 8D of the core tank 8. In this state, the front part of the core tank 8 is inserted from behind the shaft cylinder 7.
At the same time, the chuck 1 fitted with the fastener 3 is inserted from the front of the barrel 7, and the ridge 1I of the chuck 1 is press-fitted into the groove 8C formed in the front inner hole 8B of the core tank 8. The spring 9 has an inner stage 5E of the crown 5 and an outer stage 8E of the core tank 8.
It is stretched between.

Therefore, normally, the chuck 1 and the core tank 8 are urged rearward by the spring 9, and the rear portion 3B of the fastener 3 is inserted into the front inner hole 7C of the shaft cylinder 7, and
The outer flange 3 </ b> C of the fastener 3 is in contact with the front end of the shaft cylinder 7.

Further, a synthetic resin base 2 is provided on the front portion of the barrel 7.
The outer flange 3C of the fastener 3 is loosely fitted between the rear inner step 2B of the base 2 and the front end of the barrel 7 so as to be slidable in the longitudinal direction. The front part 3D of the fastener 3 is inserted into the large-diameter hole 2C of the base 2.

A rubber core holder 12 for holding the core 4 with an appropriate force is built in the base 2, and a stainless steel guide pipe 13 is fixed to the end of the base 2.

Next, a method of assembling the chuck 1 and the core tank 8 will be described.
And the spring 9 is dropped from the front of the core tank 8, and the rear part of the spring 9 is press-fitted and fixed to the projection 8 </ b> D of the core tank 8. Next, the transfer stand is moved to fit the shaft cylinder 7 from the front of the core tank 8. Further, the transfer table is moved, and the chuck 1 having the fastener 3 fitted to the head is inserted from the front of the barrel 7. Then, the rear part 3 </ b> B of the fastener 3 is inserted into the front inner hole 7 </ b> C of the barrel 7, and the ridge 1 </ b> I of the chuck 1 is inserted into the guide hole 8 </ b> A of the core tank 8. At this time, from the difference L1 between the radius of the guide hole 8A of the lead tank 8 and the radius of the front inner hole 8B of the lead tank 8, the difference L2 between the radius of the ridge portion 1I of the chuck 1 and the radius of the rear end outer periphery 1J of the chuck 1 is obtained. , The rear end of the chuck 1 is automatically moved to the center tank 8.
Is inserted into the front inner hole 8B.

When the chuck 1 is pushed in this state, the protruding portion 1I of the chuck 1 is press-fitted and connected to the concave groove 8C of the core tank 8, and the state shown in FIG. 1 is obtained. Therefore, the chuck 1 and the core tank 8 can be easily connected by an automatic machine.

Further, even when the operation is manually performed, the chuck 1 and the core tank 8 can be easily connected as compared with the conventional one, and the assembling property is improved.

The chuck 1 is made of polyacetal and has glass fibers inserted therein, and is formed by injection molding. The molded product is molded with the chuck 1 expanded.

Since the radius of curvature of the maximum diameter portion 1C of the chuck 1 is formed slightly smaller than the radius of curvature of the slide hole 2A of the base 2, when the chuck 1 is opened, the base 2 is closed.
The axis of the sliding hole 2A coincides with the axis of the
Since B is located at the center, the wick 4 in the wick tank 8 can reliably fall in the wick holding portion 1B of the chuck 1.

In addition, the radius of curvature of the maximum diameter portion 1C of the chuck 1 is formed larger than the radius of curvature of the inner hole 3A of the fastener 3, and the width of the maximum diameter portion 1C is larger than the diameter of the inner hole 3A of the fastener 3. Since the chuck 1 is formed large, the head of the chuck 1 is pressed by the fastener 3 by the spring 9, and there is no possibility that the head of the chuck 1 passes through the fastener 3 even when the chuck 1 is closed.

Further, as described above, the outer peripheral surface 1E of the raised portion 1D formed on the head of the chuck 1 has the same radius of curvature at any position in the longitudinal direction, so that the outer surface 1E is Even if the position of the fastener 3 abutting on the raised portion 1D of the chuck 1 is shifted back and forth due to the variation in diameter, the chuck 1 and the fastener 3 always abut in the same state. That is,
As shown in FIG. 12, even if the position of the fastener 3 is shifted back and forth, the chuck closed by the fastener 3 always contacts the front end of the inner hole 3A of the fastener 3 at two points on both sides of the raised portion 1D. 1
Is always in a state in which the axis of the fastener 3 coincides with that of the axis without lateral vibration.

[0025]

According to the mechanical pencil of the present invention described above, when the ridge formed at the rear portion of the chuck is inserted into the guide hole of the lead tank, the rear end of the chuck is automatically inserted into the front inner hole of the lead tank. Therefore, there is an effect that the chuck and the core tank can be connected very easily.

[Brief description of the drawings]

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

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

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

FIG. 4 is an end view showing a front end of a chuck in the 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 sectional view taken along line CC of FIG. 2;

FIG. 9 is a sectional view showing a mechanical pencil of the present invention.

FIG. 10 is a sectional view taken along line AA of FIG. 9;

FIG. 11 is a sectional view showing a state in which the chuck and the lead tank in the mechanical pencil of the present invention are disassembled.

FIG. 12 is a cross-sectional view showing a state in which a front end of a fastener contacts a raised portion of the chuck.

[Explanation of symbols]

 Reference Signs List 1 chuck 1G rear part of chuck 1 1I ridge of chuck 1 1J outer periphery of rear end of chuck 1 7 shaft cylinder 8 core tank 8A guide hole of core tank 8 8B front inner hole of core tank 8 8C concave groove of core tank 8

Claims (2)

[Claims] In a mechanical pencil, a chuck is inserted from the front of a barrel, a wick tank is inserted from the back of the barrel, and a rear portion of the chuck is press-fitted into a front inner hole of the wick tank in the barrel. The radius of the guide hole located at the front end of the tank is formed larger than the radius of the ridge formed at the rear of the chuck, and the radius of the ridge of the chuck is formed larger than the radius of the outer periphery of the rear end of the chuck, and A mechanical pencil wherein the difference between the radius of the ridge portion of the chuck and the radius of the outer periphery of the rear end of the chuck is set to be larger than the difference between the radius of the guide hole of the core tank and the radius of the front inner hole of the core tank. 2. A zipper is formed at a rear portion of the chuck, a groove is formed at a front inner hole of the core tank, and a ridge of the chuck is fitted into the groove so that the chuck is connected to the core tank. A mechanical pencil that is press-fitted to