JP6649820B2 - Writing lead gripper and mechanical pencil - Google Patents

Description

  The present invention relates to a mechanical pencil in which a writing lead is sequentially fed out by operating a knock member, and more particularly to a writing lead holding chuck and a mechanical pencil in which a chuck for holding a writing lead is improved.

As is well known, a mechanical pencil, for example, operates by knocking a knock member disposed at a tail end of a barrel so that a writing lead can be sequentially fed out from a mouth portion at a front end of the barrel. A writing core gripping chuck (hereinafter, also simply referred to as a chuck) is arranged near the mouth to perform the functions of feeding the writing core and gripping the writing core.
This chuck is formed of a metal or resin material, and particularly for low-priced products, a resin material that can be mass-produced is employed.

  According to the chuck formed of such a resin material, the gripping force of the writing lead is not sufficient as compared with the chuck made of metal. Accordingly, FIG. 6 of Patent Document 1 discloses a configuration of a chuck in which the radius of curvature at the core gripping portion of the chuck is formed to be slightly smaller than the radius of the core to be used in order to supplement the gripping force.

  According to this configuration, the gripper acts so that the corner of the chuck penetrates into the writing lead, so that the gripping force of the writing lead by the chuck can be increased. However, according to the configuration of the chuck described above, the writing lead is liable to be broken. Therefore, Patent Literature 1 discloses that this problem is improved.

JP 2000-280683 A

  By the way, the resin chuck disclosed in Patent Document 1 has a configuration in which the tip portion is divided into three parts. Such a three-part chuck has a complicated mold for resin molding, and the separation based on this is complicated. Prone to mold problems and other technical problems. Therefore, in order to avoid such a technical problem, it is desirable to use a two-part chuck. However, when the two-part chuck is formed by resin molding, another technical problem as described below occurs.

In other words, the tip of the two-divided chuck is vertically divided with respect to a surface along the axis. A V-shaped groove is formed so as to face the core holding portion of each chuck piece vertically separated from the conventional one along the axial direction.
In order to form the V-shaped grooves (core gripping portions) in the axial direction so as to face each other, it is necessary to increase the processing accuracy of the core pin arranged at the center of the chuck during resin molding of the chuck. is there.

Generally, in order to machine the core pin disposed at the center of the chuck during resin molding, first, a half-peripheral surface along the axis of a material to be the core pin is cut in an inverted V shape. Thereafter, the core pin is formed by rotating the material by 180 degrees and similarly performing an inverted V-shaped cutting process on the remaining half circumferential surface.
Therefore, there is a problem in that the position of the inverted V-shaped groove in the upper half and the lower half centered on the axis of the core pin is likely to shift during machining.

8A and 8B show an example in which the chuck 5 is resin-molded using the above-described core pin.
That is, the tip of the chuck 5 is divided vertically into a first chuck piece 5a and a second chuck piece 5b, and core holding parts 5e, 5f having a V-shaped cross section are formed on the inner surfaces of the chuck pieces 5a, 5b, respectively. They are formed to face each other.
FIG. 8A is a cross-sectional view of the chuck showing an ideal state in which the upper and lower V-shaped core holding portions 5e and 5f have no horizontal displacement, and FIG. 8B is a vertical V-shaped core holding portion. An example in which the parts 5e and 5f are displaced is shown in a cross-sectional view in a direction orthogonal to the axial direction. The diameter of the writing lead L shown in the figure is 0.5 mm.

As shown in FIG. 8A, the chuck 5 in an ideal state in which the upper and lower V-shaped core gripping portions 5e and 5f are not displaced has opposed V-shaped chucking portions respectively applied to the upper and lower chuck pieces 5a and 5b. At four points, the writing core L is gripped.
On the other hand, according to the chuck 5 in which the upper and lower V-shaped core gripping portions 5e and 5f are displaced, as shown in FIG. 8B, the V-shaped upper and lower chuck pieces 5a and 5b are respectively provided. The writing core L is gripped at two points on the diagonal lines of the core gripping portions 5e and 5f. For this reason, the position of the writing lead L held by the chuck 5 is not stable, and a shearing force acts on the writing lead L, and the writing lead L is frequently broken in the chuck 5.

  Note that the above-described positional deviation between the upper and lower V-shaped core gripping portions 5e and 5f may be caused by shrinkage during cooling of the resin even if the finishing accuracy of the core pin is high. The breakage also includes a problem that cannot be solved only by improving the finishing accuracy of the core pin.

  The present invention has been made based on the above-described technical viewpoint, and in a two-piece chuck piece, even if a mechanical displacement occurs between the first and second chuck pieces, a stable state is always maintained. An object of the present invention is to provide a writing lead holding chuck capable of holding a writing lead, and thereby to provide a mechanical pencil capable of effectively preventing breakage of the writing lead.

A first preferred embodiment of a writing lead holding chuck according to the present invention, which has been made to solve the above-mentioned problem, is a writing lead holding chuck provided with first and second chuck pieces that are divided into two at a tip end portion. a is, the the first chuck piece with the core gripping portion whose cross section perpendicular to the axial center is formed in a V-shape is formed in cross-section planar state orthogonal to axial center on the second chuck pieces Is formed, and the core gripping portion formed on the first chuck piece is formed deeper than the radius of the writing core to be gripped , and the V-shape applied to the first chuck piece is formed. The writing core is configured to be gripped by two points of a core holding part having a shape of a circle and one point of a core holding part in a planar state applied to the second chuck piece.

A second preferred embodiment of the writing lead holding chuck according to the present invention is a writing lead holding chuck provided with first and second chuck pieces that are divided into two at a tip end, and wherein the first chuck is provided. cross section into pieces perpendicular to the axial center, along with the core gripping portion is formed by a large curved surface than the curvature of the gripped writing lead, configured cross section plane orthogonal states in the axial in the second chuck pieces A core grip portion formed on the first chuck piece is formed deeper than a radius of a writing core to be gripped , and a curved surface provided on the first chuck piece is formed. The writing core is configured to be gripped at one point of the core gripping part and at one point of the planar core gripping part applied to the second chuck piece.

Further, a third preferred embodiment of the writing lead gripping chuck according to the present invention is a writing lead holding chuck provided with first and second chuck pieces divided into two at a tip end, wherein the first chuck is provided. A cross section perpendicular to the axis is formed on the piece, and a core gripping portion having a curved surface larger than the curvature of the writing core to be gripped is formed, and the cross section perpendicular to the axis is flat or the second cross section on the second chuck piece. One point of the core gripping portion is formed by a curved surface having a larger curvature than the curved surface of the core gripping portion applied to the first chuck piece, and the curved surface applied to the first chuck piece; The writing lead is configured to be gripped at one point of a core gripping portion formed by a flat surface or a curved surface applied to the second chuck piece .

In this case, the writing lead gripping chuck according to the first embodiment to the third embodiment described above is neither desirable composed of a resin material having elasticity.

In a preferred form of the writing lead holding chuck according to the third aspect , the lead holding part formed on the first chuck piece is formed shallower than a radius of the writing lead to be held, and the second chuck The lead gripping part formed on the piece is formed on the inner bottom part of the recess that is shallower than the radius of the writing lead to be gripped .

  According to the mechanical pencil employing the above-described writing core gripping chuck, it is possible to obtain the unique functions and effects described in the following column of the effects of the invention.

According to the present invention, in a writing lead gripping chuck divided into two at the tip end, even if the first and second chuck pieces opposed to each other are misaligned in molding, the first and second chuck pieces are formed. By selecting the combination configuration of the respective core gripping portions as described above, the writing core can always be gripped in a stable state.
Therefore, it is possible to provide a mechanical pencil that can effectively prevent the writing lead from being broken.

FIG. 1 is a central cross-sectional view showing an overall configuration of a mechanical pencil according to the present invention. FIG. 2 is an enlarged sectional view of a mouth portion of the mechanical pencil shown in FIG. 1. It is a top view showing the whole composition of a writing lead grasping chuck. It is sectional drawing seen from the AA line in FIG. 3A in the arrow direction. It is the front view which showed the whole structure of the writing lead holding chuck. It is a left view of a writing core holding chuck. FIG. 4 is a schematic view showing a state where the chuck piece of the first example is not shifted. FIG. 4 is a schematic diagram when a shift occurs in the chuck piece of the first example. It is the schematic diagram which showed the state in which the chuck piece of the 2nd example does not have a shift. It is a schematic diagram when the shift | offset | difference arises in the chuck piece of the 2nd example. It is the schematic diagram which showed the chuck piece of the 3rd example. It is the schematic diagram which showed the chuck piece of the 4th example. It is the schematic diagram which showed the state in which the chuck | zipper piece in the conventional chuck did not shift. It is a mimetic diagram in case a gap occurs in a piece of a conventional chuck.

Hereinafter, the overall configuration of the mechanical pencil according to the present invention will be described with reference to the drawings, and then a preferred example of a writing lead gripping chuck used for this will be described.
In each of the drawings shown below, the same parts are indicated by the same reference numerals. May be explained.

The mechanical pencil shown in FIG. 1 and FIG. 2 has a shell made of a resin cylinder 1, and the front half of the cylinder 1 is slightly reduced in diameter, and a grip member 2 is attached to the outer periphery thereof. .
Reference numeral 3 denotes a lip attached to the distal end of the barrel 1, and a female screw formed on the inner peripheral surface of the rear end of the lip 3 is formed on the outer peripheral surface of the front end of the barrel 1. It is screwed into the male screw.

A cylindrical core case 4 is accommodated in the shaft cylinder 1 coaxially with the shaft cylinder 1, and a rear end portion of the chuck 5 is fitted and connected to an inner peripheral surface of a front end portion of the core case 4. Have been.
The chuck 5 is entirely made of an elastic resin material, and has a through hole formed along the axis thereof. The tip of the chuck 5 is divided into two parts, and the divided tip is loosely fitted in a metal fastener 6 formed in a ring shape. The ring-shaped fastener 6 is mounted on the inner surface of the distal end portion of a cylindrical cylindrical chuck housing 7 arranged to cover the periphery of the chuck 5.

A distal end pipe 8 is arranged so as to protrude from the lip portion 3, and a proximal end portion of the distal end pipe 8 is fitted to an inner surface of a distal end portion of a resin holding chuck 9 located in the lip portion 2. Attached.
As shown in FIG. 2, the holding chuck 9 made of resin has a core insertion hole formed in an axial center portion thereof, and an annular groove 9a extending axially outside the core insertion hole. Is given. With this configuration, the holding chuck 9 has an effect of temporarily holding the writing lead in a state in which light friction is given to a writing lead (not shown) positioned in the lead insertion hole of the shaft center portion.

On the other hand, a coil-shaped chuck spring 11 is disposed in an axial space between the rear end of the cylindrical chuck housing 7 and the core case 4. By the action of the chuck spring 11, the chuck 5 in the chuck housing 7 is urged together with the lead case 4 in a direction of retreating in the barrel 1.
As a result, the tip of the chuck 5 is housed in the ring-shaped fastener 6, and the writing lead is held in a state of being gripped by the chuck 5.

  At the rear end of the barrel 1, a clip support 1a is formed integrally with the barrel 1, and a clip 13 is attached along the barrel 1 using the support 1a. I have. An eraser 14 is detachably attached to the tail end of the lead case 4 projecting from the rear end of the barrel 1 so as to cover the lead supply port. A knock cover 15 is attached to the lead case 4 so as to cover the outer side of the eraser 14, and the knock cover 15 is arranged so as to protrude from the rear end of the shaft cylinder 1. The cover 15 functions as a knock operation unit.

  In the mechanical pencil shown in FIG. 1, the knocking operation portion (knock cover 15) protruding from the rear end of the barrel 1 is knocked to move the lead case 4 forward in the barrel 1 and connected thereto. The chuck 5 thus moved also advances while holding a writing lead (not shown). When the tip of the chuck 5 projects from the fastener 6, the chuck is opened and the gripping state of the writing lead is released. When the knocking operation is released, the chuck 5 and the lead case 4 are retracted in the shaft cylinder 1 by the action of the chuck spring 11.

At this time, the writing lead is temporarily held in the through hole of the holding chuck 9 by friction. In this state, the chuck 5 is retracted, and its tip is accommodated in the fastener 6, so that the writing lead is gripped by the chuck 5 again.
That is, the chuck 5 releases and grips the writing lead by the back and forth movement of the chuck 5 by repeating the knocking operation to the knocking operation unit, so that the writing lead is sequentially fed forward from the tip pipe 8. Works.

3A to 3D are enlarged views of a single unit of the writing core gripping chuck 5. As described above, the chuck 5 is formed using a resin material having elasticity as a whole, for example, polyacetal, nylon, polypropylene, polyethylene, or the like.
In addition, the distal end portion (front half) of the chuck 5 is divided into two upper and lower portions along the axial direction, so that a first chuck piece 5a and a second chuck piece 5b are provided. The latter half of the chuck 5 constitutes a fitting shaft 5c fitted and attached to the above-mentioned lead case 4, and an insertion hole for a writing lead is provided in the shaft portion of the cylindrical fitting shaft 5c. 5d is formed.

Further, on the inner surfaces of the first and second chuck pieces 5a and 5b opposed to each other up and down, there are formed lead grippers 5e and 5f of a writing lead inserted into the lead insertion hole 5d.
Note that, in the chuck 5 shown in FIGS. 3A to 3D, a configuration in which the cross sections are formed in a V-shape as the core grippers 5e and 5f is illustrated.
An ideal combination of the core grippers 5e and 5f in the chuck 5 whose tip is divided into two parts by resin molding will be described later with reference to FIGS.

FIGS. 4A and 4B are cross-sectional views showing a first example of the first example. In this example, the first core gripping portion 5e formed on the first chuck piece 5a has a cross section perpendicular to the axis. It is formed in a character shape. In this case, the V-shaped first lead grip 5e is formed shallower than the radius of the writing lead L to be gripped. The second core gripping portion 5f formed on the second chuck piece 5b is formed on the inner bottom of a recess 5g shallower than the radius of the writing core L to be gripped so that the cross section orthogonal to the axis becomes planar. ing.
The second core grip 5f formed at the inner bottom of the recess 5g may be formed by a curved surface having a curvature much larger than the curvature of the writing core L.

4A is a cross-sectional view of the chuck 5 showing an ideal state in which there is no horizontal displacement between the upper and lower core grippers 5e and 5f, and FIG. 4B is a cross-sectional view of the upper and lower core grippers 5e and 5f. An example of a case where a displacement occurs is shown in a cross-sectional view in a direction orthogonal to the axial direction.
As shown in FIG. 4A, the chuck 5 in an ideal state in which the upper and lower core gripping portions 5e and 5f are not displaced has two points of a V-shaped core gripping portion 5e applied to the first chuck piece 5a. The writing core L is gripped at one point of the core gripping portion 5f formed by a flat surface or a curved surface applied to the second chuck piece 5b. The diameter of the writing lead L shown in the figure is 0.5 mm.

  On the other hand, according to the first example, even if the upper and lower core gripping portions 5e and 5f are displaced, as shown in FIG. 4B, the V-shaped core gripping portion 5e applied to the first chuck piece 5a. The writing core L can be gripped at two points and one point of the core gripping portion 5f formed by a flat surface or a curved surface applied to the second chuck piece 5b. Therefore, the position of the writing lead L gripped by the chuck 5 is stable, and unnecessary shearing force can be prevented from acting on the writing lead L, so that the writing lead L can be prevented from being broken.

FIGS. 5A and 5B are cross-sectional views showing a second example of the second embodiment. In this example, the first core gripping portion 5e formed on the first chuck piece 5a is formed from the curvature of the writing core L to be gripped. Is also constituted by a slightly larger curved surface. In this case, the first lead gripping portion 5e formed by the curved surface is configured to be shallower than the radius of the writing lead L to be gripped. The second core gripping portion 5f formed on the second chuck piece 5b is formed on the inner bottom of a recess 5g shallower than the radius of the writing core L to be gripped so that the cross section orthogonal to the axis becomes planar. ing.
The second core grip 5f formed at the inner bottom of the recess 5g is formed by a curved surface having a much larger curvature than the curved surface of the core grip 5e formed on the first chuck piece 5a. May be.

FIG. 5A is a cross-sectional view of the chuck 5 showing an ideal state in which there is no horizontal displacement between the upper and lower core grippers 5e and 5f. FIG. 5B is a cross-sectional view of the upper and lower core grippers 5e and 5f. An example of a case where a displacement occurs is shown in a cross-sectional view in a direction orthogonal to the axial direction.
As shown in FIG. 5A, the chuck 5 in an ideal state in which the upper and lower core grippers 5e and 5f are not displaced includes one point of the core gripper 5e formed by a curved surface provided on the first chuck piece 5a, The writing core L is gripped at one point of the core gripping portion 5f formed by a flat surface or a curved surface applied to the chuck piece 5b. The diameter of the writing lead L shown in the figure is 0.5 mm.

On the other hand, according to the second example, even if the upper and lower core gripping portions 5e and 5f are displaced, as shown in FIG. 5B, one point of the core gripping portion 5e due to the curved surface applied to the first chuck piece 5a. The writing core L can be gripped at one point of the core gripping portion 5f formed by a flat surface or a curved surface applied to the second chuck piece 5b.
In the second example, similarly to the first example, the position of the writing lead L held by the chuck 5 is stable, and unnecessary shearing force can be prevented from acting on the writing lead L. Breakage can be prevented.

FIG. 6 shows a third example in a similar sectional view. In the third example of the chuck 5 shown in FIG. 6, the first core gripping portion 5e formed on the first chuck piece 5a is The cross section orthogonal to the axis is formed in a V-shape. In this case, the V-shaped first lead gripping portion 5e is formed deeper than the radius of the writing lead L to be gripped. On the other hand, the second core gripping portion 5h formed on the second chuck piece 5b is configured to be planar.
That is, an isosceles triangle in which the surface of the second core gripping portion 5h is the bottom side with respect to two V-shaped sides forming the first core gripping portion 5e.
The second core gripping portion 5h may not be a flat surface as shown in the figure, but may be formed of a curved surface having a curvature much larger than the curvature of the writing core L to be gripped.

According to the third example shown in FIG. 6, the writing lead L has two points of a V-shaped lead holding portion 5e provided on the first chuck piece 5a and a flat or large surface provided on the second chuck piece 5b. It is gripped at one point of the core gripping portion 5f by a curved surface having a curvature.
The gripping state of the writing lead L does not change regardless of whether the upper and lower lead grippers 5e and 5f are not displaced or the displacement occurs.
Therefore, also in the third example, it is possible to obtain the same operation and effect as those in the first and second examples.

FIG. 7 is a cross-sectional view of the fourth example. In the fourth example of the chuck 5 shown in FIG. 7, the first core gripping portion 5e formed on the first chuck piece 5a has a grip. The writing surface L has a curved surface slightly larger than the curvature of the writing core L. In this case, the first lead gripping portion 5e formed on the curved surface is formed deeper than the radius of the writing lead L to be gripped. On the other hand, the second core gripping portion 5h formed on the second chuck piece 5b is configured to be planar.
The second core gripping portion 5h may be formed of a curved surface having a curvature much larger than the curvature of the writing core L to be gripped, instead of a planar shape as shown in the figure.

According to the example shown in FIG. 7, the writing lead L is formed by one point of the lead gripping portion 5e formed by the curved surface applied to the first chuck piece 5a and the flat surface or the curved surface having a large curvature applied to the second chuck piece 5b. It is gripped at one point of the core gripping portion 5h.
The gripping state of the writing lead L does not change regardless of whether the upper and lower lead grippers 5e and 5f are not displaced or the displacement occurs.
Therefore, also in the fourth example, the same operation and effect as those in the first and second examples can be obtained.

  Thus, according to the writing lead holding chuck according to the present invention, the writing lead can be always held in a stable state even if the first and second chuck pieces facing each other are displaced on the resin molding. . Therefore, by using this chuck for a mechanical pencil, it is possible to provide a mechanical pencil capable of effectively preventing breakage of a writing lead, and to obtain the same operational effects as described in the column of effects of the invention. it can.

Reference Signs List 1 shaft cylinder 2 grip member 3 mouth 4 core case 5 chuck 5a first chuck piece 5b second chuck piece 5c fitting shaft 5d writing lead insertion hole 5e first core gripping part 5f second core gripping part 5g concave 5h Lead gripper 6 Fastener 7 Chuck container 8 Tip pipe 9 Holding chuck 11 Chuck spring 13 Clip 14 Eraser 15 Knock cover L Writing lead

Claims (6)

A writing core gripping chuck provided with a first and a second chuck piece which is divided into two at a tip end,
The first chuck piece is formed with a core gripping portion having a V-shaped cross section orthogonal to the axis, and the second chuck piece is configured to have a flat cross section orthogonal to the axis . A core grip is formed,
The core gripping portion formed on the first chuck piece is formed deeper than the radius of the writing core to be gripped, and two points of a V-shaped core gripping portion provided on the first chuck piece; at one point of lead gripping portion of the planar state that has been subjected to the second chuck pieces, writing lead gripping chuck, characterized in that gripping the writing lead. A writing core gripping chuck provided with a first and a second chuck piece which is divided into two at a tip end,
A cross section orthogonal to the axis is formed on the first chuck piece, and a core grip portion having a curved surface larger than the curvature of the writing core to be gripped is formed, and a cross section orthogonal to the axis is formed on the second chuck piece. A core grip portion configured in a planar state is formed,
The core gripping portion formed on the first chuck piece is formed deeper than the radius of the writing core to be gripped, and one point of the core gripping portion formed by a curved surface provided on the first chuck piece, and at one point of lead gripping portion of the planar state that has been subjected to the second chuck pieces, writing lead gripping chuck, characterized in that gripping the writing lead. A writing core gripping chuck provided with a first and a second chuck piece which is divided into two at a tip end,
A cross section orthogonal to the axis is formed on the first chuck piece, and a core grip portion having a curved surface larger than the curvature of the writing core to be gripped is formed, and a cross section orthogonal to the axis is formed on the second chuck piece. A core grip portion is formed by a curved surface having a larger curvature than a flat surface or a curved surface of the core grip portion applied to the first chuck piece,
Gripping the writing lead at one point of a core gripping portion with a curved surface applied to the first chuck piece and at one point of a core gripping portion with a flat or curved surface applied to the second chuck piece. Characteristic writing core gripper chuck. The writing lead holding chuck according to any one of claims 1 to 3, wherein the writing lead holding chuck is made of a resin material having elasticity. The core gripping portion formed on the first chuck piece is formed shallower than the radius of the writing core to be gripped, and the core gripping portion formed on the second chuck piece has a recess which is shallower than the radius of the writing core to grip. The writing lead holding chuck according to claim 3 or 4 , wherein the chuck is formed at an inner bottom portion of the writing lead.   A mechanical pencil, comprising the writing lead gripping chuck according to any one of claims 1 to 5.

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