JP2019038134A - mechanical pencil - Google Patents

Abstract

To provide a mechanical pencil which can improve the feel received by the user at the time of attaching and detaching the knock cover to the lead case and can reduce the degree of occurrence of core breakage due to the chuck accompanying the withdrawal operation of the knock cover from the lead case.SOLUTION: There is provided a mechanical pencil in which a writing core L is sequentially drawn out from a tip 3 of the front end portion of the barrel by knocking operation of a knock cover 14 detachably attached to the tail end of the core case 4, in which the knock cover 14 is detachably attached to the core case by fitting so as to cover the tail end of the cylindrical lead case 4 from the outside. Further, a fitting protrusion 4c of the knock cover 14 is formed on the outer peripheral surface of the lead case 4, and an opening 4d which penetrates the cylindrical outer peripheral surface of the lead case adjacent to the fitting protrusion 4c in the circumferential direction is formed.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a mechanical pencil in which a writing core is sequentially drawn out by a knocking operation of the knock cover, and in particular, a problem of causing breakage (core breakage) to the writing core when the knock cover is removed and attached due to replenishment of the writing core and use of an eraser. This relates to a mechanical pencil that eliminates the problem.

  The mechanical pencil generally operates by knocking a knock cover disposed at the tail end portion so that the writing core is sequentially drawn out from the front end portion of the front end portion of the barrel. In order to perform the function of feeding out the writing core and gripping the writing core, a writing core gripping chuck (hereinafter also simply referred to as a chuck) is arranged near the tip, and this chuck is made of a metal or a resin material. It has been adopted.

In this type of mechanical pencil, a knock cover is detachably attached by fitting at the tail end portion of the lead case that accommodates the spare writing lead, and directly or via other members to the tip portion of the lead case. Products with chucks are provided.
Patent Document 1 discloses a mechanical pencil in which a knock cover is detachably attached to a tail end portion of a lead case, and a chuck is attached to a tip portion of the lead case via a lead guide member.

According to the knock type mechanical pencil having the configuration disclosed in Patent Document 1, for example, when trying to replenish the writing core or when using an eraser attached to the core case, the knock cover is removed from the core case. An operation to pull out is required.
When pulling out the knock cover, a force that is dragged by the knock cover and retracts to the lead case works, so that the force to retract also acts on the chuck attached to the lead case directly or via another member. To do.

Accordingly, since the chuck is pulled into the ring-shaped fastener, a force to grip the core more strongly by the chuck acts on the writing core. This effect becomes more severe as the fitting force of the knock cover to the lead case increases.
Therefore, when a color lead (colored pencil lead) inferior in mechanical strength is used, the degree of damage such as broken core is increased. Further, in the type in which the clip is formed on the knock cover, the grip force of the knock cover at the fingertip can be increased due to the presence of the clip, and as a result, the grip force stronger by the chuck in the above-described operation of pulling out the knock cover. The damage given to the writing core by the chuck is greater.

JP 2002-113986 A

  By the way, when the fitting force of the knock cover with respect to the lead case is weak, it is possible to avoid applying an excessive force to the chuck when the knock cover is pulled out of the lead case. Therefore, the degree of damage such as broken core is reduced. However, there may be a problem that the user feels bad and the commercial value is impaired, such as poor click feeling received in the operation of attaching / detaching the knock cover.

  On the other hand, when the fitting force of the knock cover to the core case is strong, as described above, problems such as increasing the degree of core breakage caused by the chuck are caused. The fitting force of the knock cover to the core case described above often depends on variations in the molding dimensions of each part, and by controlling the molding dimensions in the resin molding of the core case and the knock cover, the fitting force of both is always within a certain range. It is difficult to fit in.

  The present invention has been made based on the above-described technical viewpoint, and in particular, by improving the feeling of the user when the knock cover is attached to and detached from the core case by devising a part of the core case. At the same time, it is an object of the present invention to provide a mechanical pencil that can reduce the degree of occurrence of core breakage caused by a chuck associated with the operation of pulling out the knock cover from the core case.

  The mechanical pencil according to the present invention, which has been made to solve the above-mentioned problems, is such that the writing core is sequentially formed from the tip of the front end portion of the shaft cylinder by the knocking operation of the knock cover detachably attached to the tail end portion of the core case. A mechanical pencil that is extended, wherein the knock cover is detachably attached to the core case by fitting so as to cover the tail end portion of the core case formed in a cylindrical shape from the outside, and A fitting protrusion of the knock cover is formed on the outer peripheral surface of the core case, and an opening penetrating the cylindrical outer peripheral surface of the core case is formed adjacent to the fitting protrusion in the circumferential direction. It is characterized by being.

  In this case, the fitting protrusion of the knock cover formed on the outer peripheral surface of the core case preferably has an inclined portion whose diameter increases from the tail end side of the core case toward the front of the core case, and the inclined portion. Subsequently, an upright portion parallel to the axis of the core case and a falling portion that is perpendicular to the axis of the core case and has a smaller diameter with respect to the upright portion are provided.

  And it is preferable that the writing core accommodated in the said core case is a color pencil core containing resin which melt | dissolved or included the dye in the pencil core body.

According to the mechanical pencil described above, the fitting projection of the knock cover is formed on the outer peripheral surface of the core case, and penetrates the cylindrical outer peripheral surface of the core case adjacent to the fitting projection in the circumferential direction. An opening is formed.
Therefore, when the knock cover is attached to and detached from the tail end portion of the core case, the opening formed in the core case can effectively bend (bend) the fitting protrusion of the knock cover. .

  Thereby, the fluctuation | variation of the fitting force between both resulting from the variation in shaping | molding of a core case and a knock cover can be relieve | moderated significantly. Therefore, especially when the knock cover is attached to the lead case, the user can obtain a certain click feeling and avoid applying excessive force to the chuck when the knock cover is pulled out of the lead case. Can do. As a result, it is possible to provide a mechanical pencil with a reduced degree of occurrence of core breakage caused by the chuck.

1 is a partial cross-sectional view showing an overall configuration of a mechanical pencil according to the present invention. (A) is a front view of a core case, (B) is sectional drawing of the state which fractured | ruptured the front half part. (A) is the front view of the state which rotated the core case shown in FIG. 2 90 degree | times to the axial direction, (B) is sectional drawing of the state which fractured | ruptured the front half part. It is sectional drawing to which the a part enclosed by the chain line in FIG. 1 was expanded.

Hereinafter, the overall configuration of the mechanical pencil according to the present invention will be described with reference to FIG. The mechanical pencil has an outer shell formed of a resin shaft 1, and the front half of the shaft 1 is slightly reduced in diameter, and a grip member 2 is attached to the outer periphery thereof.
Reference numeral 3 denotes a tip portion attached to the tip portion of the shaft tube 1, and a female screw formed on the inner peripheral surface of the rear end portion of the tip portion 3 is formed on the outer peripheral surface of the front end portion of the shaft tube 1. The tip portion 3 is detachably attached to the shaft tube 1 by being screwed into the male screw.

A cylindrical core case 4 is accommodated coaxially with the shaft cylinder 1 in the shaft cylinder 1, and a rear end portion of the chuck 5 is fitted and connected to the inner peripheral surface of the tip portion of the core case 4. Has been.
The chuck 5 is entirely made of a resin material having elasticity, and a core insertion hole through which the writing core L passes is formed along the axis. The tip of the chuck 5 is divided into two parts, and the divided tip is mounted so as to be loosely fitted in a metal fastener 6 formed in a ring shape. The ring-shaped fastener 6 is attached to the inner surface of the tip of a chuck housing 7 formed in a cylindrical shape so as to cover the periphery of the chuck 5.

A tip pipe 8 is disposed so as to protrude from the tip portion 3, and the base end portion of the tip pipe 8 is fitted to the inner surface of the tip portion of the resin-made holding chuck 9 located in the tip portion 2. Has been attached.
The resin holding chuck 9 has a core insertion hole formed in the shaft center portion, and an annular groove 9a is formed along the axial direction outside the core insertion hole. With this configuration, the holding chuck 9 serves to temporarily hold the writing core L in a state where light friction is applied to the writing core L located in the core insertion hole of the shaft center portion.

On the other hand, a coil-shaped chuck spring 11 is disposed in the axial space between the rear end portion of the cylindrical chuck housing 7 and the core case 4. Due to the action of the chuck spring 11, the chuck 5 in the chuck housing 7 is urged together with the core case 4 in the direction of retreating in the shaft cylinder 1.
As a result, the tip of the chuck 5 is accommodated in the ring-shaped fastener 6, and the writing core L is held by the chuck 5.

  An eraser 13 is detachably attached to the tail end portion of the core case 4 protruding from the rear end portion of the shaft cylinder 1 so as to cover the core supply port of the core case 4. The knock cover 14 is detachably attached to the core case 4 by fitting the eraser 13 and the tail end of the core case 4 from the outside. A clip support 15a formed integrally with the clip 15 is fitted into and coupled to the end of the knock cover 14.

According to the mechanical pencil shown in FIG. 1, by knocking the knock cover 14 (in the illustrated example, the clip support 15a attached to the front end of the knock cover) protruding from the rear end portion of the shaft tube 1, The lead case 4 moves forward in the shaft cylinder 1, and the chuck 5 connected to the lead case 4 also moves forward while holding the writing lead L. Then, the tip of the chuck 5 protrudes from the fastener 6 so that the chuck 5 is opened and the gripping state of the writing core L is released.
Further, by releasing the knocking operation, the chuck 5 and the core case 4 are retracted in the shaft cylinder 1 by the action of the chuck spring 11.

At this time, the writing core L is temporarily held by friction in the core insertion hole of the holding chuck 9. In this state, the chuck 5 retreats and the tip end portion is accommodated in the fastener 6 so that the writing core L is gripped by the chuck 5 again.
That is, the chuck 5 releases and grips the writing core L by the forward and backward movements of the chuck 5 by repeating the knocking operation to the knock cover 14, and thereby the writing core L is sequentially forwarded from the tip pipe 8. Acts like being fed out.

2 and 3 are a front view and a sectional view of the core case 4 in a state where the core case 4 is rotated 90 degrees in the axial direction.
The core case 4 is formed in a cylindrical shape as described above, and is formed so that the outer diameter becomes thinner stepwise from the tail end portion to the front end portion. The tail end portion is formed with an eraser receiving port 4a which also serves as a core replenishing port, and a receiving portion 4b formed in a hook shape is formed to protrude outward slightly. When the knock cover 14 is attached to the tail end portion of the core case 4 as shown in FIG. 1, the receiving portion 4b functions as a stopper by contacting the front end portion of the core case 4.

  The knock cover 14 is fitted to the inner peripheral surface of the knock cover 14 on the outer peripheral surface opposite to the core case 180 degrees between the collar-shaped receiving portion 4b and the tail end portion of the core case 4. A fitting protrusion 4c to be held is formed. In addition, the relationship between the more detailed form of this fitting protrusion 4c and the annular | circular shaped protrusion formed in the knock cover 14 side is demonstrated later based on FIG.

An opening 4d penetrating the cylindrical outer peripheral surface of the core case 4 is formed so as to oppose the fitting protrusion 4c in the circumferential direction. And these opening parts 4d are each formed long in the axial direction. That is, the fitting protrusions 4 c and the openings 4 d are alternately formed at 90 ° intervals along the circumferential direction of the core case 4.
In addition, by forming the opening 4d as described above, the resin material of the fitting protrusion 4c adjacent to the opening 4d can be effectively bent (bent). The opening 4d is formed long in the axial direction, so that the bending action can be set larger. The effect of this bending will be described later with reference to FIG.

A protrusion 4e having an arcuate cross section is formed in an annular shape at a portion slightly narrowing the outer diameter in front of the hook-shaped receiving portion 4b, that is, at a substantially central portion in the length direction of the core case 4.
As shown in FIG. 1, the arc-shaped protrusion 4e reduces the gap between the inner peripheral surface of the shaft tube 1 as much as possible, and the core case 4 is orthogonal to the shaft with respect to the shaft tube 1 during the knocking operation. It acts to prevent rattling in the direction that you do.

  Further, two protrusions 4 f formed in a ring shape are formed on the inner peripheral surface of the tip portion of the core case 4. This protrusion 4f is fitted to the end of the chuck 5 and contributes to attaching the chuck 5 to the tip of the lead case 4 without wobbling. Further, a stepped portion 4g for reducing the outer diameter of the tip portion is formed on the outer peripheral surface of the tip portion of the core case 4. The step portion 4g functions as a receiving portion on the core case 4 side of the chuck spring 11 described with reference to FIG.

On the other hand, a pair of small-diameter holes 4h are formed between the arcuate protrusion 4e and the tip of the core case 4 so as to face each other. The small diameter hole 4h is generated when the core case 4 is injection molded.
That is, in order to injection mold the core case 4, a first mold and a second mold (upper and lower split molds) (not shown) and a core pin for forming a shaft hole of the core case 4 are used. The core pin needs to be accurately positioned between the first mold and the second mold. For this reason, the first mold and the second mold have a small diameter in order to support the core pin in the center. The support pins are formed to face each other.
Therefore, the pair of small-diameter holes 4h are left as holes for the support pins formed in the respective molds when the first mold and the second mold are released.

4 is an enlarged cross-sectional view of a portion surrounded by a chain line in the mechanical pencil shown in FIG.
As shown in FIG. 4, an annular protrusion 14 a having a circular cross section is formed along the inner peripheral surface of the knock cover 14 attached to the tail end portion of the core case 4. Yes.
On the other hand, the fitting protrusion 4c for the knock cover 14 is formed on the outer peripheral surface of the core case 4 as described above. As shown in FIG. 4, the fitting protrusion 4 c formed on the core case 4 side includes an inclined portion 4 c 1 that increases in diameter from the tail end side of the core case 4 toward the front of the core case, and the inclined portion. Subsequent to 4c1, an upright portion 4c2 parallel to the axis of the core case 4 and a falling portion 4c3 perpendicular to the axis of the core case 4 and having a smaller diameter with respect to the upright portion 4c2.

Accordingly, when the knock cover 14 is attached to the tail end portion of the lead case 4, the annular protrusion 14a on the knock cover 14 side rides on the inclined portion 4c1 on the lead case 4 side, and then the protrusion 14a stands up. It moves on the part 4c2. At this time, due to the above-described bending action by the opening 4d formed in the core case 4, the fitting protrusion 4c is slightly bent toward the axial center, and the annular protrusion 14a falls into the falling part 4c3 as it is.
That is, in the state shown in FIG. 4, the front end portion of the knock cover 14 comes into contact with the bowl-shaped receiving portion 4 b shown in FIG. 1, and the mounting of the knock cover 14 to the core case 4 is completed.

At this time, the fitting protrusion 4c on the core case 4 side returns to the deflection toward the axial center side, and a light impact sound is generated between the knock cover 14 and the reaction of the return. At the same time, the user can obtain a certain click feeling as a feeling of wearing the knock cover 14.
Thus, the user can confirm that the knock cover 14 is securely attached to the lead case 4 side, as well as the light impact sound described above, as a click feeling.

On the other hand, when pulling out the knock cover 14 from the lead case 4, the annular protrusion 14a on the knock cover 14 side rides on the standing part 4c2 on the lead case 4 side from the state shown in FIG.
At this time, due to the bending action described above, the fitting projection 4c is slightly bent toward the axial center side, and the annular projection 14a moves along the inclined portion 4c1, and the knock cover 14 can be pulled out from the core case 4. it can.

Thus, even when the knock cover 14 is pulled out from the core case 4, the fitting protrusion 4 c is slightly bent toward the axial center side by the above-described bending action, so that the core case 4 and the knock cover 14 are Due to variations in molding, variations in the fitting force between the two can be effectively suppressed. Therefore, it is possible to avoid applying excessive force to the chuck 5 due to the operation of pulling the knock cover 14 from the lead case 4.
Thereby, it is possible to provide a mechanical pencil in which the degree of occurrence of breakage of the core by the chuck 5 is reduced.

By the way, according to the mechanical pencil according to the present invention, in the operation of pulling out the knock cover 14 from the core case 4, the degree of occurrence of core breakage by the chuck 5 can be reduced. A mechanically fragile colored pencil lead can be preferably used.
A color pencil lead that can be suitably used for a mechanical pencil includes a resin in which a dye is dissolved or encapsulated in a pencil lead.

That is, in this colored pencil lead, the resin encapsulating the dye is soluble in the organic solvent, and the resin in which the dye is dissolved or encapsulated is a dyeing resin, and this is filled in the pores of the pencil core. Composed.
According to this colored pencil lead, characteristics excellent in hue and eraser erasability can be exhibited without impairing strength and light resistance.
And by utilizing this colored pencil lead in the above-described mechanical pencil according to the present invention, the characteristics of this colored pencil lead can be sufficiently exhibited.

On the other hand, if the eraser 13 attached to the mechanical pencil according to the present invention has the same color as the color written with the writing core (colored pencil core) L, the eraser 13 is erased when the drawn stroke is erased by the eraser 13. 13 can be made inconspicuous.
Note that the eraser 13 having the same color as the color tone written with the color pencil lead can be said to be in a range that can be recognized as the same color through human vision, and is slightly different in shades of color, light and dark, and strong and weak. The difference can be regarded as the same color. Specifically, the hue of the Munsell display system can be regarded as the same color within 10 hues and within 3 brightness and saturation.

  Further, the colored pencil lead may be a thermochromic core using a thermochromic microcapsule that changes color by frictional heat or the like as a colorant. A thermochromic core, at least (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) an electron-receiving reaction by the components (a) and (b) is reversibly generated in a specific temperature range. 10% by weight or more of a reversible thermochromic microcapsule pigment encapsulating a temperature-sensitive color-changing color memory composition comprising a reaction medium to be formed, comprising a shaping material, a binder, and a binder resin at room temperature (for example, 25 The predetermined color (first color) is maintained at a temperature (° C.), and when the temperature is raised to a predetermined temperature (for example, 60 ° C.), the color changes to another color (second color), and then the predetermined temperature (for example, −10 ° C.) When it is cooled down, it has the property of returning to the original color (first color) again. In general, the second color may be colorless, and the stroke drawn with the first color (for example, red) may be heated to be colorless. Accordingly, the frictional body 9 rubs against the paper surface or the like on which the drawn line is written to generate frictional heat, thereby changing the drawn line to colorless. Of course, the second color may be a color other than colorless.

  When a thermochromic core is used, the eraser 13 is made of a rubber material such as silicone rubber, nitrile rubber, ethylene propylene rubber or ethylene propylene diene rubber, or a thermoplastic elastomer such as styrene elastomer, olefin elastomer or polyester elastomer. Rubber elastic materials, a mixture of two or more rubber elastic materials, and a low-abrasion rubber elastic material containing no plasticizer composed of a mixture of a rubber elastic material and a synthetic resin. The low wear property mentioned here is preferably a friction tool having a taper wear amount of less than 15 mg according to JIS K7204 test method H22.

In the mechanical pencil described above, the opening 4 d formed in the core case 4 and the fitting protrusion 4 c formed adjacent to the opening 4 d in the circumferential direction are along the circumferential direction of the core case 4. Are alternately formed at intervals of 90 degrees.
The opening 4d and the fitting protrusion 4c are preferably configured as shown in the drawing when mold release by resin molding is taken into account, but the number of the opening 4d and the fitting protrusion 4c is limited to the illustrated example. Even if three or more are formed along the circumferential direction, the same effect can be obtained.

DESCRIPTION OF SYMBOLS 1 Shaft cylinder 2 Grip member 3 Tip part 4 Core case 4a Eraser accommodation port (core supply port)
4b receiving portion 4c fitting projection 4d opening 4e arc-shaped projection 4f protrusion 4g stepped portion 4h small diameter hole 5 chuck 6 fastener 7 chuck housing 8 tip pipe 9 holding chuck 9a annular groove 11 chuck spring 13 eraser 14 knock cover 14a Annular protrusion 15 Clip 15a Clip support body L Writing core

Claims (3)

A mechanical pencil in which the writing core is sequentially drawn out from the tip of the front end portion of the barrel by knocking a knock cover detachably attached to the tail end portion of the core case,
The knock cover is detachably attached to the core case by fitting so as to cover the tail end portion of the core case formed in a cylindrical shape from the outside, and the knock cover is disposed on the outer peripheral surface of the core case. The mechanical pencil is characterized in that an opening that penetrates the cylindrical outer peripheral surface of the core case is formed adjacent to the fitting protrusion in the circumferential direction.   The fitting projection of the knock cover formed on the outer peripheral surface of the core case has an inclined portion whose diameter increases from the tail end side of the core case toward the front of the core case, and the core case following the inclined portion. The mechanical pencil according to claim 1, further comprising: an upright portion parallel to the axis; and a falling portion having a diameter that is perpendicular to the axis of the core case with respect to the upright portion.   The mechanical pencil according to claim 1 or 2, wherein the writing core accommodated in the lead case is a colored pencil lead containing a resin in which a dye is dissolved or encapsulated in a pencil lead body.

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