JP2021024169A - Middle core for lead holder and method for manufacture thereof - Google Patents

Abstract

To prevent deformation of a chuck which is connected to an advance/retreat tube.SOLUTION: A middle core for lead holder comprises: a chuck 10 which pinches a lead core x by a plurality of claws parts 11; an advance/retreat tube 30 which is annularly connected to a rear end side of the chuck 10; and a support tube 40 which inserts a connection part of the advance/retreat tube 30 and the chuck 10 and supports both so as to be capable of advancing and retreating. In the middle core for lead pencil which delivers the lead core x pinched by the chuck 10 by advance/retreat of the advance/retreat tube 30 relative to the support tube 40, a front end side of the advance/retreat tube 30 is provided with a notch 33 for dividing a peripheral surface thereof in a circumferential direction, and the rear end side of the chuck 10 is fitted into the front end side of the advance/retreat tube 30 having the notch 33.SELECTED DRAWING: Figure 4

Description

The present invention relates to a lead for a mechanical pencil used for a multifunctional writing instrument having a plurality of types of writing instrument functions such as a ballpoint pen and a mechanical pencil, a mechanical pencil having a single writing unit, and a method for manufacturing the same. ..

Conventionally, in this type of invention, for example, as described in Patent Document 1, a metal chuck which is divided into a plurality of parts on the tip side and has a claw portion and a metal chuck which is annularly covered and connected to the rear end side of the chuck. There is a lead for mechanical pencils with a cylindrical joint (advance / retreat tube).
In such a mechanical pencil core, the rear end side of the chuck is press-fitted to the front end side of the joint, and these two members are connected and fixed.

Japanese Unexamined Patent Publication No. 2014-172377

However, according to the above-mentioned prior art, when a metal chuck is press-fitted into the front end side of the joint, the claw portion on the front end side of the chuck may be deformed at the narrowed portion on the base side thereof. ..
Therefore, for example, it is conceivable to form the joint from a flexible synthetic resin material, but in this case, due to the dimensional accuracy of the joint formed by injection molding or the like, deformation during press fitting, or the like. , The friction between the inner peripheral surface of the joint and the outer peripheral surface of the lead core to be inserted increases, or the lead core gets caught in the minute steps generated at the connection point between the chuck and the joint, and the lead core advances due to its own weight. (Drop of lead core) may be hindered.

The present invention has the following configurations in order to solve at least a part of the above problems.
A chuck that sandwiches a lead core with a plurality of claws, an advancing / retreating pipe that is annularly connected to the rear end side of the chuck, and a support pipe that inserts the advancing / retreating pipe and the connecting portion of the chuck to support the lead / retreating tube. In a mechanical pencil center core having a lead core sandwiched between the chucks by advancing and retreating the advancing / retreating pipe facing the support pipe, the peripheral wall thereof is divided in the circumferential direction on the front end side of the advancing / retreating pipe. A lead for a mechanical pencil, characterized in that a notch is provided so as to be provided, and the rear end side of the chuck is fitted into the front end side of the advancing / retreating pipe having the notch.

Since the present invention is configured as described above, it is possible to reduce the pressure input when the chuck is fitted into the advancing / retreating pipe and prevent the chuck from being deformed.

It is a full sectional view which shows an example of the core for a mechanical pencil which concerns on this invention. It is a semi-cross-sectional view which shows the main part of the core for the mechanical pencil enlarged. It is a full sectional view which shows the manufacturing procedure of the core for the mechanical pencil in order (a)-(b). It is a full cross-sectional view which shows the manufacturing procedure of the core for the mechanical pencil in order (c) to (e).

In this embodiment, the following features are disclosed.
The first feature is that a chuck that sandwiches a lead core with a plurality of claws, an advancing / retreating pipe that is annularly connected to the rear end side of the chuck, and a connecting portion between the advancing / retreating pipe and the chuck can be inserted to advance / retreat. In a mechanical pencil center core provided with a support pipe for supporting the mechanical pencil, and the lead core sandwiched between the chucks is fed out by advancing and retreating the advancing / retreating pipe facing the support pipe, the lead core is provided on the front end side of the advancing / retreating pipe. A notch is provided so as to divide the peripheral wall in the circumferential direction, and the rear end side of the chuck is fitted into the front end side of the advancing / retreating pipe having the notch (see FIGS. 1 to 4).

As a second feature, the peripheral wall of the advancing / retreating pipe is provided with a thin portion on the rear side of the rear end portion of the chuck and having a wall thickness smaller than that of the rear end portion (see FIG. 2).

As a third feature, the inner peripheral surface of the support tube is provided with a large diameter portion on the front side and a small diameter portion reduced in diameter on the rear side of the large diameter portion, and the support tube has the notch portion. The front end side portion having the above is slidably arranged in the small diameter portion (see FIGS. 1 and 4 (e)).

The fourth feature is the method for manufacturing a lead for a mechanical pencil, in which a front end side portion having the notch portion of the advance / retreat pipe is inserted into the support pipe and arranged in front of the small diameter portion. The step of fitting the rear end side of the chuck into the front end side portion of the advance / retreat pipe having the notch portion, and the advance / retreat pipe is retracted with respect to the support pipe to make the notch portion of the advance / retreat pipe. The step of arranging the front end side portion having the portion in the small diameter portion is included (see FIGS. 3 to 4).

<Specific embodiment>
Next, a specific embodiment having the above characteristics will be described in detail with reference to the drawings.

FIG. 1 shows an example of a lead for a mechanical pencil according to the present invention.
The mechanical pencil core 1 includes a chuck 10 for sandwiching and releasing the lead core x by a plurality of claw portions 11, a clutch 20 that can be fitted and detached in an annular shape with respect to the plurality of claw portions 11, and after the chuck 10. The advancing / retreating pipe 30 which is connected to the tubular portion 12 on the end side in an annular shape, the support pipe 40 which inserts the front end side of the advancing / retreating pipe 30 and the rear end side of the chuck 10 to support the advancing / retreating pipe 40, and the support pipe 40. The tip metal 50 detachably connected to the front end side of the pipe, the lead breaker 60 supported in the tip metal 50, and the front end portion are brought into contact with the rear end of the support pipe 40 to be annular to the rear side of the advancing / retreating pipe 30. The lead core x sandwiched between the chucks 10 is fed out by advancing and retreating the advancing / retreating pipe 30 facing the support pipe 40.
The mechanical pencil lead 1 is connected to the front end side of the cylindrical lead tank 90 and is housed in a multifunction writing tool or a mechanical pencil barrel.

The chuck 10 is formed of an elastically flexible metal material (for example, brass), is arranged concentrically so as to be located around the lead core x, and is separated in the circumferential direction. It has a claw portion 11 (about 2 to 4) and a tubular portion 12 connected in an annular shape to the rear end side of the claw portion 11. Then, the chuck 10 inserts and fixes the tubular portion 12 into the inner peripheral surface on the front end side of the advancing / retreating pipe 30, and advances / retreats integrally with the advancing / retreating pipe 30.

Each claw portion 11 is formed in the shape of a long piece extending in the front-rear direction, and the front end side portion thereof is formed in a wide shape protruding outward in the radial direction. A clutch 20 is fitted to the outer peripheral portion of this wide portion so as to be disengaged rearward.
The plurality of claw portions 11 grip the lead core x by bending inward in the radial direction, and elastically restore and open to release the lead core x.

The tubular portion 12 is formed in a substantially cylindrical shape and is fitted into the front end side portion of the advancing / retreating pipe 30. An insertion portion 12a and a locking recess 12b are provided in the fitting portion on the rear end side of the tubular portion 12.

The insertion portion 12a is formed in a tapered tubular shape whose outer peripheral surface is gradually reduced in diameter toward the rear.
The locking recess 12b is a groove that is continuous in the circumferential direction on the front side of the insertion portion 12a and is provided in an annular shape over the entire circumference.

The clutch 20 is a substantially cylindrical member having a mortar-shaped inner peripheral surface that expands in diameter toward the front, and is formed of a hard material such as metal. The clutch 20 is supported so as to advance and retreat by a predetermined amount between the step portion 51 in the tip metal 50 and the front end portion of the support pipe 40.
Then, when the clutch 20 is advanced, it fits into the wide portions of the plurality of claw portions 11, bends the front portion of the chuck 10 inward in the radial direction, and when the clutch 20 is disengaged from the claw portion 11 rearward. , The front portion of the chuck 10 is elastically restored and bent outward in the radial direction.

The advancing / retreating pipe 30 is formed of a metal (for example, brass or the like) into a long cylindrical shape.
The advancing / retreating pipe 30 has an insertion cylinder portion 30a inserted from the rear side of the support pipe 40 and a receiving portion 30b that expands in diameter on the rear side of the insertion cylinder portion 30a to receive the rear end seat portion of the compression coil spring 70. And a connecting cylinder portion 30c extending rearward from the receiving portion 30b and fitted and connected in the core tank 90.

The insertion tube portion 30a is formed in a long substantially cylindrical shape, the front end side thereof is inserted into the rear end side of the support tube 40, and the compression coil spring 70 is annularly attached to the outer peripheral surface on the rear end side. The outer peripheral surface of the insertion tube portion 30a on the front end side is in sliding contact with the inner peripheral surface of the support tube 40 on the rear end side as the entire advancing / retreating pipe 30 moves forward and backward.
On the front end side of the insertion tube portion 30a, a fitting tube portion 31, a thin wall portion 32, and a notch portion 33 are provided so as to be located in the support tube 40 (see FIG. 2).

The fitting cylinder portion 31 is a substantially tubular portion located at the foremost end of the advancing / retreating pipe 30, and is formed in a cylindrical shape having a relatively small wall thickness.
On the inner peripheral surface of the fitting cylinder portion 31 on the front end side, a locking projection 31a that protrudes inward in the radial direction and is continuous in the circumferential direction is provided.

The thin-walled portion 32 is a portion on the rear side of the rear end portion of the fitted chuck 10 and having a wall thickness smaller than that of the rear end portion. According to the illustrated example, the thin-walled portion 32 is formed into a thin-walled cylindrical shape by scraping off the outer peripheral surface of the advancing / retreating pipe 30 in an annular shape.
The thin wall portion 32 is thinner than the rear side portion, but is thicker than the minimum wall thickness portion of the front fitting cylinder portion 31.

The front end side portion of the advancing / retreating pipe 30 peripheral wall is divided in the circumferential direction, and a plurality of (for example, 2 to 3) cutout portions 33 are provided at intervals in the circumferential direction (see FIG. 2).
According to the illustrated example, each cutout portion 33 is formed in a slit shape extending rearward with the front end opened, and is provided in a front-rear range including the fitting cylinder portion 31 and the thin-walled portion 32.

Further, the receiving portion 30b is an annular protrusion protruding outward in the radial direction on the rear end side of the insertion cylinder portion 30a, and receives the rear end seat portion of the compression coil spring 70.
According to the illustrated example, the receiving portion 30b is formed in an annular shape continuous with the entire circumference, but as another example, a mode in which the receiving portion 30b partially protrudes outward in the radial direction in the circumferential direction. It is possible to adopt a mode in which an annular member separate from the advancing / retreating pipe 30 is fitted.

Further, the connecting cylinder portion 30c is formed in a substantially cylindrical shape in which the outer peripheral surface on the rear end side is gradually reduced in diameter toward the rear, and is inserted and fitted into the inner peripheral surface on the front end side of the core tank 90.

Further, the support tube 40 is formed in a long cylindrical shape by a metal material (for example, brass or the like).
The support pipe 40 is supported so as to be able to advance and retreat by inserting the connection portion between the advance / retreat pipe 30 and the chuck 10 (in other words, the front end side of the advance / retreat pipe 30 and the rear end side of the chuck 10), and the front end side of the claw portion 11 and the support pipe 40. The clutch 20 is projected forward. The rear end of the clutch 20 is in contact with the front end of the support tube 40.

The inner peripheral surface of the support tube 40 is provided with a large diameter portion 41 located on the front end side and a small diameter portion 42 reduced in diameter on the rear side of the large diameter portion 41. The support pipe 40 has a front end side portion having a notch 33 of the advancing / retreating pipe 30 slidably arranged in the small diameter portion 42.

A tip 50 is fitted and connected to the front end side of the support tube 40 in an annular shape.
The tip 50 is a substantially cylindrical member formed of a hard material such as metal (for example, brass), and is connected to the front end side of the support tube 40 by connecting means such as fitting or screwing (according to the illustrated example). It is detachably connected by (screw).
The front end side of the tip 50 is formed in a tapered shape whose diameter gradually decreases toward the front. The inner peripheral surface of this tapered portion is formed in a cylindrical shape that is in sliding contact with the lead core x.
A core breaker 60 is fitted in the tip 50 on the rear side of the tapered portion and on the front side of the chuck 10 so as not to advance or retreat.

The core breaker 60 is formed in a substantially cylindrical shape from an elastic material such as rubber or an elastomer resin. A conical surface for guiding the lead core x forward is formed on the latter half side of the inner peripheral surface of the core breaker 60, and a cylinder elastically pressed against the lead core x on the front side of the conical surface. A surface is provided.

The compression coil spring 70 is annularly mounted on the latter half side of the insertion tube portion 30a of the advancing / retreating pipe 30, and the front end portion thereof is brought into contact with the rear end portion of the support pipe 40, and the rear end portion thereof is received at the advancing / retreating pipe 30. It abuts on 30b, faces the support pipe 40, and urges the advancing / retreating pipe 30 and the chuck 10 to the rear.

Next, the manufacturing procedure of the mechanical pencil core 1 having the above configuration will be described in detail.
First, as shown in FIG. 3A, the front end side portion of the advancing / retreating pipe 30 equipped with the compression coil spring 70 is inserted into the support pipe 40 from the rear side.

Next, as shown in FIG. 3B, the compression coil spring 70 is compression-deformed to obtain the front end side portion of the advancing / retreating pipe 30 (specifically, a part of the fitting cylinder portion 31 and the thin-walled portion 32). It is arranged in front of the small diameter portion 42 of the support pipe 40.

Next, as shown in FIG. 4C, the chuck 10 equipped with the clutch 20 is moved rearward and inserted into the support tube 40.

Then, as shown in FIG. 4D, the rear end side of the chuck 10 (specifically, the insertion portion 12a, the locking recess 12b, etc.) is fitted into the front end side portion having the notch 33 of the advancing / retreating pipe 30.
At the time of this fitting, the front end side portion of the advancing / retreating pipe 30 is flexibly deformed in the diameter expansion direction due to the configuration of the notch portion 33, the thin wall portion 32, and the like. Therefore, the pressure input at the time of fitting can be made relatively small, and it is possible to prevent each claw portion 11 of the chuck 10 from being deformed at the narrowed portion on the proximal end side thereof. ..

Next, as shown in FIG. 4 (e), the advancing / retreating pipe 30 is retracted with respect to the support pipe 40, and the connection points between the chuck 10 and the advancing / retreating pipe 30 (in other words, the notch 33 and the fitting cylinder 31 and the like). Is arranged in the small diameter portion 42 of the support tube 40.

According to the above step, the outer peripheral surface of the fitting cylinder portion 31 into which the rear end side of the chuck 10 is fitted comes into contact with or approaches the inner peripheral surface of the small diameter portion 42 of the support tube 40. Therefore, even if a force acts forward or radially outward on the rear end side of the chuck 10, the front end side of the advancing / retreating pipe 30 is deformed in the radial direction, and the chuck 10 comes off from the advancing / retreating pipe 30. It is possible to prevent such a thing from happening.

According to the above embodiment, as a preferred example, the notch 33 is formed in a slit shape, and as another example, the notch 33 has a V-shaped notch, a semicircular notch, a curved line, or the like. It is also possible to make a notch shape other than.

Further, the present invention is not limited to the above-described embodiment, and can be appropriately changed without changing the gist of the present invention.

10: Chuck 11: Claw part 20: Clutch 30: Advance / retreat pipe 31: Fitting cylinder part 32: Thin wall part 33: Notch part 40: Support pipe 41: Large diameter part 42: Small diameter part 50: Tip 60: Core breaker 70 : Compression coil spring x: Lead core

Claims (4)

A chuck that sandwiches a lead core with a plurality of claws, an advancing / retreating pipe that is annularly connected to the rear end side of the chuck, and a support pipe that inserts the advancing / retreating pipe and the connecting portion of the chuck to support the advancing / retreating. In the center core for mechanical pencils, the lead core sandwiched between the chucks is drawn out by advancing and retreating the advancing / retreating pipe facing the support tube.
A notch is provided on the front end side of the advancing / retreating pipe so as to divide the peripheral wall in the circumferential direction, and the rear end side of the chuck is fitted on the front end side of the advancing / retreating pipe having the notch. Core for mechanical pencils. The mechanical pencil according to claim 1, wherein the peripheral wall of the advancing / retreating pipe is provided with a thin portion which is rearward from the rear end portion of the chuck and whose wall thickness is smaller than that of the rear end portion. The core. The inner peripheral surface of the support tube is provided with a large diameter portion on the front side and a small diameter portion reduced in diameter on the rear side of the large diameter portion, and the support tube has a front end side portion having the notch. The lead for a mechanical pencil according to claim 1 or 2, wherein the lead is slidably arranged in the small diameter portion. The method for manufacturing a lead for a mechanical pencil according to claim 3.
A step of inserting the front end side portion of the advancing / retreating pipe having the notch portion into the support pipe and arranging the portion in front of the small diameter portion.
A step of fitting the rear end side of the chuck into the front end side portion of the advancing / retreating pipe having the notch portion, and
Manufacture of a lead for a mechanical pencil, which comprises a step of retracting the advancing / retreating pipe with respect to the support pipe and arranging a front end side portion of the advancing / retreating pipe having the notch portion in the small diameter portion. Method.

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