JP2001018579A - Mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical pencil in which the number of parts is decreased much more than that for the conventional one. SOLUTION: In a writing front barrel 10 constituted of a writing front barrel main body 11 and a front member 12, a lead delivery mechanism 14 is built and the lead delivery mechanism 14 has a chuck ring 16 the flange part 16a of which is hooked on the apex of the writing front barrel main body 11, a chuck 18 the head part 18a of which is fitted in the chuck ring 16 and the back end part 18b of which is extended in the writing front barrel 10 and a spring 22 which is placed between the apex part of a lead tank 20 and the apex part of the writing front barrel main body 11 and energizes backward the chuck 18 and the lead tank 20. The back end part 18b of the chuck 18 is pressed into the apex of the lead tank 20 and the chuck 18 and the lead tank 20 are integrally movable to the writing front barrel 10 in the shaft direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical pencil, and more particularly, to a mechanical pencil with a reduced number of parts compared to conventional mechanical pencils.

[0002]

2. Description of the Related Art Conventionally, as a mechanical pencil of this type, a mechanical pencil in which a center feeding mechanism is built in a writing shaft is generally used. The lead-out mechanism is typically composed of a lead tank containing a lead, a chuck fixed to the tip of the lead tank for tightening and feeding the lead, a chuck ring for tightening the chuck, and a chuck ring. There is known a sleeve having a sleeve that regulates the rearward movement of the sleeve and a spring that is between the sleeve and the core tank and that is an elastic body that urges the core tank and the chuck rearward. Then, the sleeve is fixed to the writing shaft. A knock bar is connected to the rear end of the core tank, and an eraser is detachably fitted into the knock bar.

[0003]

However, in such a conventional mechanical pencil, although the number of parts is reduced and simplified to some extent, there is a problem that the number of parts is still large and the manufacturing cost is high.

[0004] The present invention has been made in view of the above problems, and has as its object to provide a mechanical pencil capable of reducing the number of parts.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a writing lead shaft having a built-in lead sending mechanism including a chuck and a chuck ring for fastening and sending out a lead. In a mechanical pencil, the rear end of the chuck is fixed to the front end of a lead tank located in the writing shaft, the lead tank extends rearward from the writing shaft, and the rear end of the writing shaft is located at the rear end of the lead tank. Are formed integrally with each other with a gap larger than the knock allowance, and a clip is formed integrally with the writing rear shaft of the core tank.

According to a second aspect of the present invention, the total length of the writing shaft of the core tank according to the first aspect is at least １ ／ of the total length of the writing shaft. I do.

According to a third aspect of the present invention, the clip according to the first or second aspect extends forward from the writing rear shaft portion, and its tip reaches the side peripheral surface of the writing destination shaft. I do.

According to a fourth aspect of the present invention, the writing shaft according to any one of the first to third aspects includes a writing shaft main body and a tip attached to a tip of the writing shaft main body. Wherein the lead-out mechanism is configured such that the chuck ring locked at the tip of the writing tip shaft main body, the chuck whose head is fitted into the chuck ring, the tip end of the tip tank and the writing tip shaft. And a spring interposed between the springs and biasing the chuck and the lead tank rearward.

According to a fifth aspect of the present invention, in the one of the first to fourth aspects, an eraser is detachably fitted to a rear end of the writing shaft of the lead tank. On the inner peripheral surface of the rear end of the writing shaft, a rib is formed at the front end of the eraser, the rib being in contact with the rear end surface.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a mechanical pencil according to an embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a writing shaft. The writing shaft 10 is composed of a writing shaft 11 and a tool 12 attached to the tip of the writing shaft 11 by screwing or the like. . A plurality of (three in the example in the figure, the remaining one is invisible) elastic deformation piece portions 12a extending rearward from the tip of the tip tool 12 are integrally formed inside the tip of the tip tool 12. Have been. These elastic deformation pieces 12a are
It is deformable in the radial direction, and is elastically contacted with a lead through which the leading tool 12 is inserted so that the lead can be held.

In the writing shaft 10, a center feeding mechanism 14 is provided.
Is built-in. The lead-out mechanism 14 includes a chuck ring 16 having a flange 16a fixed to the tip of the writing shaft 11 and a head 18a inside the chuck ring 16.
Is fitted and the rear end 18b is
And a chuck 18 extending inside. The rearward movement of the chuck ring 16 is restricted by locking the flange 16 a to the tip of the writing shaft main body 11. The rear end portion 18b of the chuck 18 is press-fitted and fixed in the front end of the core tank 20 in the writing shaft 10, so that the chuck 18 and the core tank 20 can move integrally with respect to the writing shaft 10. It has become. The lead-out mechanism 14
Further, a spring 22 is interposed between the tip of the lead tank 20 and the tip of the writing tip shaft 10 and biases the chuck 18 and the lead tank 20 rearward.

The lead tank 20 extends inside the writing shaft 10 and extends further rearward from the rear end of the writing shaft 10. The portion of the core tank 20 extending rearward from the writing shaft 10 is a writing rear shaft portion 20a whose diameter is increased to about the same outer diameter as the writing shaft main body 11 of the writing shaft 10. A gap S equal to or greater than the knock allowance is provided between the portion 20a and the rear end of the writing shaft 10. The post-writing shaft portion 20a, together with the writing shaft 10, constitutes the entire writing shaft of the mechanical pencil, and the total length of the post-writing shaft portion 20a is the writing shaft 10a.
Is 1/4 or more of the total length of. Shaft part 2 after writing
A clip 24 is formed integrally with Oa. The clip 24 has a proximal end 24a connected to the post-writing shaft 20a, and one distal end 24b connected to the post-writing shaft 20a.
In this embodiment, the length may reach the side peripheral surface of the writing destination shaft 10 beyond the gap S.

An eraser 26 is detachably fitted at the rear end of the post-writing shaft portion 20a of the core tank 20. On the inner peripheral surface of the rear end of the writing rear shaft portion 20a, a plurality of ribs 20b are formed at the front end of the eraser 26 to abut on the rear end surface thereof to position the eraser 26. Since the eraser 26 is positioned by the plurality of ribs 20b, the occurrence of sink marks during molding of the core tank 20 can be suppressed as compared with the case where an annular projection is formed on the inner peripheral surface of the post-writing shaft portion 20a. it can. Further, an eraser cover 28 is detachably connected to the post-writing shaft portion 20a in order to protect a portion of the eraser 26 protruding from the rear end of the post-writing shaft portion 20a. However, the eraser cover 28 can of course be omitted for the purpose of further increasing the number of parts.

The assembling of the mechanical pencil constructed as described above is performed as follows.

The spring 2 extends from the rear end of the writing shaft body 11.
2. Insert the lead tank 20, insert the chuck ring 16 and the chuck 18 from the tip of the writing shaft main body 11, and press-fit the rear end 18 b of the chuck 18 into the tip of the lead tank 20. As a result, the chuck ring 16 is
The spring 22 is sandwiched between the writing tip shaft main body 11 and the core tank 20 and is assembled. Next, the writing tip shaft body 11
The eraser 26 and the eraser cover 28 are attached to the post shaft 20a of the lead tank 20, and the assembly is completed.

The operation of the mechanical pencil is performed in the same manner as in a conventional mechanical pencil. That is, when the writing rear shaft portion 20a of the lead tank 20 is knocked forward from the rear, the chuck 18 and the chuck ring 16 connected to the lead tank 20 are knocked.
Moves forward in the leading tool 12 and sends out the core L forward,
When the chuck ring 16 comes into contact with the step 12b formed on the inner surface of the leading tool 12 and is prevented from moving forward, only the chuck 18 moves forward to release the tightening of the core L. Since the lead is held by the elastically deformable piece 12a of the leading tool 12, the lead L maintains the forward position while the writing rear shaft 20
When the knock of a is released, the lead tank 20, the chuck 18, and the chuck ring 16 are retracted and returned to the original positions by the urging force of the spring 22, and the lead L is tightened again. In this way, the lead L is sent out by the amount of advance of the chuck ring 16.

The replenishment of the core L is performed by the eraser cover 28.
By removing the eraser 26 from the writing shaft portion 20a of the core tank 20, the core can be inserted from the rear open end of the core tank 20. The wick L is guided to a funnel-shaped portion 20 c formed near the front end of the rib 20 b of the wick tank 20, and is moved to the tip of the wick tank 20.

As described above, since the core tank 20, the writing rear shaft portion 20a, and the clip 24 are integrally formed, the number of parts is reduced. Since a gap S equal to or larger than the knock allowance is formed between the post-writing shaft portion 20a and the writing tip shaft 10, knock does not occur.

Further, since the clip 24 integrated with the lead tank 20 reaches the side peripheral surface of the writing shaft 10 beyond the gap S, the writing rear shaft portion 20a at the rear end of the lead tank 20 is formed. Is long and the center of gravity is shifted to the rear side of the core tank 20, the distal end portion 24b of the clip 24 extends to the vicinity of the side peripheral surface of the writing shaft 10, so that the writing rear shaft portion 20 is formed.
a can be prevented from rattling.

Furthermore, in the present embodiment, the flange 16a of the chuck ring 16 of the center feeding mechanism 14 is directly locked to the tip of the writing shaft 10, and the chuck ring 16 is moved backward by the writing shaft 10. Can be eliminated, and a sleeve for regulating the backward movement of the chuck ring in the conventional center feeding mechanism can be dispensed with, and the number of parts is further reduced.

Next, FIG. 2 is a diagram showing a second embodiment of the present invention.

This embodiment differs from the first embodiment in that the writing shaft 30 is formed as an integral product instead of using the sleeve of the center feeding mechanism. That is, the lead-out mechanism 34 of this embodiment includes a chuck 38 for tightening and sending out the lead, and a head 38 a of the chuck 38.
And a sleeve 39 for restricting the chuck ring 36 from moving backward. The rear end portion 38b of the chuck 38 is
The chuck 38 and the core tank 40 can be integrally moved in the axial direction with respect to the writing destination shaft 30 by being press-fitted and fixed in the tip of the core tank 40 located inside. Lead feeding mechanism 3
Reference numeral 4 further includes a spring 42 disposed between the leading end of the lead tank 40 and the leading end of the sleeve 39 to urge the chuck 38 and lead tank 40 rearward. A core pipe 44 for holding the core L is provided in the tip of the writing tip 30.

The sleeve 39 is provided with a plurality of flexible pieces 39a extending radially outward. The flexible pieces 39a are inserted into stopper holes 30a provided on the inner wall of the writing tip shaft 30, and the sleeve 39, As a result, a center feeding mechanism 34 is assembled in the writing tip shaft 30. Since this configuration is the same as that of Japanese Patent Application No. 7-6213 filed by the present applicant, a detailed description of the configuration will be omitted.

The lead tank 40 extends inside the writing shaft 30 and extends further rearward from the rear end of the writing shaft 30. A portion of the core tank 40 extending rearward from the writing shaft 30 is a writing rear shaft portion 40a whose outer diameter is increased to about the same diameter as the writing shaft 30, and the writing rear shaft portion 40a and the writing shaft. 3
A gap S equal to or larger than the knock allowance is provided between the rear end of the vehicle and the rear end of the zero. The post-writing shaft portion 40a forms the entire writing shaft of the mechanical pencil together with the writing tip shaft 30, and the total length of the writing post shaft portion 40a is at least 1/4 of the total length of the writing tip shaft 30. ing. The clip 24 is formed integrally with the writing rear shaft portion 40a. The clip 24 is the same as in the first embodiment. An eraser 26 is detachably fitted into the rear end of the post-writing shaft portion 40a, and a rib 40b whose rear end surface is in contact with the front end of the eraser 26 on the inner peripheral surface of the rear end of the writing post shaft portion 40a. Are formed in the same manner as in the first embodiment.

In this embodiment, after the lead-out mechanism 34 and lead tank 40 are integrally assembled, these assembled parts are inserted from the rear end of the writing shaft 30, and the sleeve 39 is inserted.
The assembly is completed by inserting the flexible piece 39a through the guide groove 30b formed in the writing shaft 30 to the stopper hole 30a.

The function of this mechanical pencil is as follows.
Although the description is omitted since it is the same as that of the embodiment, the core tank 40 and the writing rear shaft 40 are also provided in this embodiment.
a and the clip 24 are integrally formed,
The number of parts is reduced. Also, the core feeding mechanism 3
Although the number of parts is increased because the sleeve 4 has the sleeve 39, the writing point shaft 30 can be formed as an integrated product, so that the number of parts can be reduced as in the first embodiment.

[0028]

As described above, claims 1 to 5
According to the described invention, since the core tank, the writing rear shaft portion, and the clip are integrally formed, the number of parts is reduced. Since a gap equal to or larger than the knock allowance is formed between the enlarged writing rear shaft portion and the writing front shaft, knocking of the writing rear shaft portion is not hindered.

According to the second aspect of the present invention, the entire writing axis of the mechanical pencil can be constituted by the writing axis and the writing axis of the lead tank.

According to the third aspect of the present invention, since the clip integrated with the lead tank reaches the side peripheral surface of the writing shaft, the writing rear shaft portion at the rear end of the lead tank is provided. Even if the length is long, it is possible to prevent the shaft portion from rattling after writing.

Further, according to the fourth aspect of the present invention, since the chuck ring of the lead-out mechanism is locked to the tip of the writing shaft body, the rearward movement of the chuck ring in the conventional lead-out mechanism is prevented. The regulating sleeve can be dispensed with, and the number of parts can be further reduced.

According to the fifth aspect of the present invention, the positioning of the eraser can be performed at the rear end of the rib formed on the inner peripheral surface of the rear end of the writing shaft.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a mechanical pencil according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a mechanical pencil according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Writing tip shaft 11 Writing tip spindle main body 12 Tip tool 14 Core feeding mechanism 16 Chuck ring 18 Chuck 20 Core tank 20a Writing rear shaft part 20b Rib 22 Spring 24 Clip 26 Eraser 30 Writing tip axis 34 Core feeding mechanism 36 Chuck ring 38 Chuck 40 core tank 40a post-writing shaft 40b rib

Claims (5)

[Claims] 1. A mechanical pencil in which a lead feeding mechanism including a chuck and a chuck ring for tightening and feeding a lead in a writing destination shaft is provided, wherein a rear end of the chuck is located in the writing destination shaft. Fixed to the tip, the lead tank extends to the back from the writing shaft, and the writing rear shaft part is enlarged at the rear end of the core tank with a gap equal to or more than the knock allowance between the writing head and the rear end of the writing shaft. Is formed integrally, and a clip is formed integrally with a shaft portion of the lead tank after writing. 2. The total length of the writing rear shaft portion of the lead tank is at least １ ／ of the total length of the writing shaft.
The described mechanical pencil. 3. The mechanical pencil according to claim 1, wherein the clip extends forward from a writing rear shaft portion, and a tip thereof reaches a side peripheral surface of a writing destination shaft. 4. The writing tip shaft comprises a writing tip spindle body and a tip attached to the tip of the writing tip spindle body, and the lead-out mechanism is locked at the tip of the writing tip spindle body. The chuck ring, the chuck whose head is fitted into the chuck ring, a spring inserted between the tip of the lead tank and the writing shaft, and biasing the chuck and the lead tank rearward, The mechanical pencil according to any one of claims 1 to 3, comprising: 5. A rear end of a writing shaft of the core tank,
5. An eraser is detachably fitted therein, and a rib is formed on an inner peripheral surface of a rear end of the writing rear shaft portion at a front end of the eraser to contact the rear end surface.
The mechanical pencil described in the item.