JP2016221814A - mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cases where an outer peripheral part of a pencil lead is shoved and where the pencil lead is broken.SOLUTION: In a mechanical pencil that dispenses a pencil lead 1 while bringing it into sliding contact with an inner wall surface of a lead insertion hole 12a, chamfered parts 12a1 and 12a2 reducing a diameter toward the inside of the lead insertion hole are provided on the end side of the lead insertion hole 12a.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a mechanical pencil in which a lead core is extended from the front end of a shaft tube.

Conventionally, in this type of invention, like the one described in Patent Document 1, a shaft cylinder (1), a slider (14) that slides by a predetermined amount on the front end side of the shaft cylinder, and fixed in the slider In addition, there is a mechanical pencil provided with a lead protection tube (16) through which a lead lead is inserted, and a lead lead fed by a lead feeding mechanism is inserted through the lead protection tube (16) and protrudes forward. In addition, the number in the said parenthesis shows the code | symbol in patent document 1. FIG.
By the way, in the conventional mechanical pencil as described above, since a force is applied to the lead core in the rearward direction and a radial force is applied to the lead core, the outer peripheral surface of the lead core is in the core protection tube (16). There is a case where the lead core is pressed by the corner portion at the front end of the core insertion hole and scraped, or the lead core is easily broken due to this. Also, when the lead core is inserted into the core protection tube (16), the outer periphery of the lead core is scraped off by the corner portion of the rear end of the core insertion hole, or the lead core is There is also a possibility that it will be bent by contacting the corner portions before and after the core insertion hole.

JP 2001-39081 A

  This invention is made | formed in view of the said conventional situation, The process made into the subject is providing the mechanical pencil which can reduce that the outer peripheral part of a lead lead is shaved or a lead lead is broken. is there.

  One means for solving the above-mentioned problem is that the lead core is extended while being slidably contacted with the inner wall surface of the core insertion hole on the front side of the shaft tube, and the core insertion hole is provided at the end side of the core insertion hole. A chamfered portion that is reduced in diameter is provided.

  Since this invention is comprised as demonstrated above, it can reduce that the outer peripheral part of a lead core cuts or a lead core breaks.

It is a longitudinal section showing an example of a mechanical pencil concerning the present invention. It is a longitudinal cross-sectional view which shows the front opening of the mechanical pencil. It is a principal part longitudinal cross-sectional view which shows the writing state by the mechanical pencil. It is a longitudinal section showing other examples of a tip. It is a principal part longitudinal cross-sectional view which shows the other examples of the mechanical pencil concerning this invention. It is a longitudinal cross-sectional view which shows the slider of the mechanical pencil.

One of the features of the present embodiment is that, in the mechanical pencil that is extended while sliding the lead core to the inner wall surface of the core insertion hole on the front side of the shaft tube, the core insertion hole is provided at the end side of the core insertion hole. A chamfered portion that decreases in diameter was provided.
Here, the “end side of the core insertion hole” includes both the front end side and the rear end side of the core insertion hole.
According to the said structure, it can reduce that a lead core is scraped or it becomes easy to bend | rubbed by rubbing to the edge part of a core insertion hole.

  As another feature, the chamfered portion is formed to be reduced in a convex curved shape toward the inside of the core insertion hole in order to more effectively reduce the lead core scraping (see FIGS. 2 and 6). ).

  As another feature, the chamfered portion is provided on the front end side of the core insertion hole in order to reduce the occurrence of lead lead scraping or core breakage due to radial force applied to the lead lead particularly during writing ( (See FIG. 3).

  Further, as another feature, a mechanical pencil comprising a slider that moves forward relative to the shaft tube and the lead core by a force in the outer direction of the shaft tube received from the lead core on the front end side of the shaft tube, While providing the said core insertion hole, the said chamfering part was provided in the edge part side of this core insertion hole (refer FIG.5 and FIG.6).

  Next, a preferred embodiment having the above features will be described in detail with reference to the drawings.

FIG. 1 shows an example of a mechanical pencil according to the present invention.
This mechanical pencil A includes a shaft cylinder 10 and a lead core feeding mechanism 20 accommodated in the shaft cylinder 10, and advances the lead core 1 in the shaft cylinder 10 by the operation of the lead core feeding mechanism 20, While sliding in contact with the inner wall surface of the core insertion hole 12a on the front end side of the shaft tube 10, the shaft cylinder 10 is fed forward of the core insertion hole.

The shaft tube 10 includes a long cylindrical shaft body 11 having a front shaft and a rear shaft, and a front end portion 12 connected to the front end side of the shaft body.
In the illustrated example of the shaft cylinder 10, the shaft cylinder main body 11 is composed of a plurality of cylindrical members such as a front shaft and a rear shaft, and the front end portion 12 is detachably connected to the front end side thereof. As another example of the shaft tube 10, a single member can be used.

The lead lead feeding mechanism 20 is a mechanism that advances the lead lead 1 in the lead tank 21 by an operation from the outside and feeds it forward of the leading end portion 12.
The lead core feeding mechanism 20 in the illustrated example is a known type in which the lead core 1 held by the chuck 23 is fed forward of the chuck 23 by a knocking operation of the knock portion 22 protruding rearward from the rear end of the shaft cylinder 10. Mechanism.
The lead core feeding mechanism 20 may be a mechanism that feeds the lead core 1 by an operation received from the outside. For example, the lead core 1 is fed by an operation of pressing a button provided on the side surface of the shaft cylinder. It is possible to replace with a mechanism, a mechanism that feeds the lead core 1 by an operation of shaking the whole shaft cylinder, a mechanism that feeds the lead core 1 by an operation of rotating the rear end side of the core tank, and the like. is there.

  The leading end portion 12 is formed in a tapered substantially conical cylindrical shape, has a core insertion hole 12a on the front end side of the center portion thereof, and the lead core 1 fed from the chuck 23 on the rear side of the core insertion hole 12a. A core breaker 24 that elastically holds is fitted.

The core insertion hole 12 a is a long cylindrical hole that approaches or contacts the outer peripheral surface of the lead core 1 on the foremost end side of the leading end portion 12.
On the front end side of the core insertion hole 12a, a front side chamfered portion 12a1 that is reduced in diameter toward the rear is formed. In addition, a rear side chamfered portion 12a2 that is reduced in diameter toward the front is formed on the rear end side of the concentric insertion hole 12a.

  The front side chamfered portion 12a1 is formed in a convex curved shape that reduces the diameter of the core insertion hole 12a toward the rear at the intersection of the front end surface of the front opening 12 and the inner peripheral surface of the core insertion hole 12a.

Further, the rear side chamfered portion 12a2 is inserted in the forward direction at the intersection of the lead core introduction surface 12b behind the core insertion hole 12a in the front opening 12 and the inner peripheral surface of the core insertion hole 12a. The hole 12a is formed in a convex curved shape that reduces the diameter.
The lead core introduction surface 12b is a tapered conical surface in which the lead core 1 advanced by the lead core feeding mechanism 20 is guided into the core insertion hole 12a.

Next, the characteristic effect of the mechanical pencil A having the above-described configuration will be described in detail.
When the lead core 1 moves forward by the operation of the lead core feeding mechanism 20, the front end portion of the lead core 1 further moves forward while being corrected toward the center of the shaft cylinder by the lead core introduction surface 12b, and a convex curved rear side chamfered portion It passes through 12a2 and is inserted into the core insertion hole 12a. Therefore, unlike the prior art, the outer peripheral portion of the lead core 1 is not rubbed against the corner portion or the like at the rear end of the core insertion hole, and the outer peripheral portion of the lead core 1 can be prevented from being scraped.

Further, when writing is performed with the front end portion of the lead core 1 protruding forward from the front end portion of the core insertion hole 12a (see FIG. 3), the front end side of the lead core 1 is rearward and radially outward. Force is applied, and the outer peripheral portion of the lead core 1 is pressed against the front end side of the inner peripheral surface of the core insertion hole 12a. Thus, unlike the prior art, the outer peripheral portion of the lead core 1 does not hit or rub against the corners or the like, and the outer peripheral portion of the lead core 1 can be reduced from being scraped or broken.
Even when a relatively strong force in the radial direction is applied to the lead core 1 due to a drop impact or the like, there are no corners on the front and rear end sides of the inner peripheral wall of the core insertion hole 12a. There is no possibility of being cut or broken by being pressed by a corner or the like.
Therefore, according to the mechanical pencil A having the above-described configuration, it is possible to prevent the core scraping or the core breakage from occurring during the lead-out operation of the lead core 1, during writing, or when receiving a drop impact.

In the mechanical pencil A having the above-described configuration, the front side chamfered portion 12a1 and the rear side chamfered portion 12a2 are formed in a convex curved surface as a preferable aspect for effectively preventing the outer periphery of the lead core from being scraped or the lead core from being broken. However, as another example, it is possible to replace the front opening 12 with a front opening 12 ′ shown in FIG. The front opening 12 ′ has a front side chamfering portion 12a1 ′ and a rear side chamfering portion 12a2 ′ that are C-chamfered over the entire circumference on the front end side and the rear end side of the core insertion hole 12a, respectively.
Also in this other example, the lead core 1 can be prevented from being scraped or bent by the C-chamfered front side chamfer 12a1 ′ and the rear side chamfer 12a2 ′.

Next, a mechanical pencil B which is a second embodiment will be described (see FIGS. 5 and 6).
The mechanical pencil B includes a slider 40 that moves forward relative to the shaft cylinder 30 and the lead core 1 by a force in the outer diameter of the shaft cylinder received from the lead core 1 on the front end side of the shaft cylinder 30. The side has a core insertion hole 12a similar to that described above.

  The shaft cylinder 30 is formed in a long cylindrical shape from a single member or a plurality of members, and the front end side of the slider 40 housed therein is protruded from the opening edge 31 on the front end side.

  The slider 40 is a substantially cylindrical member, has a cam slope 41 on the outer peripheral portion thereof, and has a core insertion hole 12a on the front end side of the inner peripheral portion.

  The cam slant surface 41 is formed in a conical shape with a diameter increasing toward the front, and is disposed so as to be in sliding contact with the opening edge 31 described above.

  The core insertion hole 12a is disposed on the front end side in the slider 40 and has a front side chamfer 12a1 and a rear side chamfer 12a2 on the front end side and the rear end side, respectively, as in the mechanical pencil A described above. .

The slider 40 having the above-described configuration is held so that the cam inclined surface 41 is slidably contacted with the opening edge 31 of the front end of the shaft tube 30 and is movable in the forward oblique diameter outward direction. It is urged rearward by 51 (coil spring in the illustrated example). In FIG. 5, reference numeral 52 denotes a receiving member that is integrally connected to the slider 40 and receives the rear end portion of the urging member 51.
The urging force of the urging member 51 causes the slider 40 to slide in contact with the opening edge 31 when the excessive writing pressure is applied to the lead core 1 in the backward and radially outward directions. The slider 40 is appropriately set so as to move forward relative to the lead core 1 and the shaft tube 30 and to return the slider 40 backward when the writing pressure is removed.

A lead core feeding mechanism 60 is provided on the rear side of the slider 40.
The lead lead feeding mechanism 60 is a mechanism that feeds out the lead lead 1 held by the chuck 61 by a knocking operation of a knock portion (not shown) protruding rearward from the rear end of the shaft cylinder 30. Other mechanisms can be used for the lead lead feeding mechanism 60 in the same manner as the description of the lead lead feeding mechanism 20 described above.
The lead core feeding mechanism 60 is engaged with the shaft cylinder 30 via the holding member 62 so that the lead cylinder feeding mechanism 60 cannot advance and retract with respect to the shaft cylinder 30 and finely moves in the radial direction as the slider 40 moves. To be held.
Further, the lead core feeding mechanism 60 is urged forward by an urging member 63 (in the illustrated example, a coil spring) locked in the shaft tube 30. The urging force of the urging member 63 causes the lead wick 1 and the lead wick feeding mechanism 60 to retreat when excessive writing pressure is applied to the lead wick 1 sandwiched by the chuck 61 in the rear of the shaft cylinder. As such, it is set appropriately.

Next, the characteristic effect of the mechanical pencil B having the above configuration will be described in detail.
First, when the lead core 1 is advanced from the lead core feeding mechanism 60 and advances, or when writing is performed with the front end portion of the lead core 1 protruding forward from the front end portion of the core insertion hole 12a, the drop impact Is added, the outer periphery of the lead core 1 is scraped or broken by the front side chamfering portion 12a1 and the rear side chamfering portion 12a2 of the core insertion hole 12a in the same manner as the mechanical pencil A described above. Can be prevented.

Further, as a unique action of this mechanical pencil B, when excessive writing pressure is applied to the lead core 1 in the normal writing posture in the rear and radial directions, the slider 40 is opposed to the shaft cylinder 30 and the lead core 1. It moves forward and covers and protects the front end side of the lead core 1.
When the slider 40 moves forward, the front end side of the core insertion hole 12a is a convex curved front side chamfered portion 12a1 having no corners, so that the outer peripheral surface of the lead core 1 is formed by the front end side of the core insertion hole 12a. It can reduce that it is shaved.
Further, when the excessive writing pressure is removed and the slider 40 moves backward relative to the shaft tube 30 and the lead core 1, the rear end side of the core insertion hole 12a has a convex curved front surface with no corners. Since the portion 12a2 is formed, the outer peripheral surface of the lead core 1 can be reduced from being scraped by the rear end side of the core insertion hole 12a.

Further, as a unique action of the mechanical pencil B, when excessive writing pressure is applied to the lead core 1 in the rear of the shaft cylinder, the lead core 1 and the lead core feeding mechanism 60 cause the biasing member 63 to contract. However, since the slider 40 moves backward relative to the slider 40, the front end side of the lead core 1 can be covered and protected by the slider 40.
When the lead core 1 is retracted, the front end side of the core insertion hole 12a is a convex curved front side chamfer 12a1 having no corners. Therefore, the outer peripheral surface of the lead core 1 is formed by the front end side of the core insertion hole 12a. It is possible to reduce the amount of cutting.
Further, when excessive writing pressure to the rear of the shaft cylinder is removed, the lead core 1 and the lead core feeding mechanism 60 move forward relative to the slider 40 and return to the original state. At the time of this return operation, the rear end side of the core insertion hole 12a is a convex curved rear side chamfer 12a2, so that the outer peripheral surface of the lead core 1 is scraped by the rear end side of the core insertion hole 12a. This can be reduced.

  Therefore, according to the mechanical pencil B having the above-described configuration, the slider 40 or the lead 40 is caused due to excessive writing pressure with respect to the lead core 1 during the feeding operation of the lead core 1, during writing, or when receiving a drop impact. When the lead 1 moves back and forth, it is possible to prevent the lead from being cut or broken.

  In the above-described embodiment, a single-function mechanical pencil is configured as a specific preferred example. However, the front side chamfer 12a1 (or 12a1 ′) or the rear side surface described above is used for the mechanical pencil refill in the multifunctional writing instrument. It is also possible to provide a take-up portion 12a2 (or 12a2 ′).

  In the above embodiment, the front side chamfered portion 12a1 (or 12a1 ′) or the rear side chamfered portion 12a2 (or 12a2 ′) is formed in the conical cylindrical front opening 12 or the core insertion hole 12a in the slider 40. However, as another example, a similar chamfered portion can be provided on the end side of the elongated pipe-shaped core insertion tube.

  Further, in the mechanical pencil B described above, the front side chamfered portion 12a1 and the rear side chamfered portion 12a2 are formed in a convex curved surface shape as a particularly preferable aspect. The chamfered front side chamfered portion 12a1 ′ and the rear side chamfered portion 12a2 ′ shown in FIG.

1: Lead core 10, 30: Shaft cylinder 12, 12 ': Front opening 12a: Core insertion hole 12a1, 12a1': Front side chamfer 12a2, 12a2 ': Rear side chamfer 20, 60: Lead core feeding mechanism 40 : Slider A, B: Mechanical pencil

One means for solving the above-mentioned problems is that the front end of the shaft tube is provided with a slider that moves forward relative to the shaft tube and the lead core by a force in the outer diameter of the shaft tube received from the lead core, and the lead core is moved to the slider. In the mechanical pencil that is extended forward while sliding on the inner wall surface of the front core insertion hole, the front end side of the core insertion hole is reduced to a convex curved surface with no corners toward the rear in the core insertion hole. A chamfered portion is provided.

Claims (4)

  In a mechanical pencil that is fed out while sliding the lead core against the inner wall surface of the core insertion hole on the front side of the shaft cylinder, a chamfered portion that is reduced in diameter toward the inside of the core insertion hole is provided on the end side of the core insertion hole. Mechanical pencil characterized by that.   The mechanical pencil according to claim 1, wherein the chamfered portion is formed so as to be reduced in a convex curved shape toward the core insertion hole.   The mechanical pencil according to claim 1, wherein the chamfered portion is provided on a front end side of the core insertion hole. A mechanical pencil having a slider that moves forward relative to the shaft tube and the lead core by a force in the outer direction of the shaft tube received from the lead core on the front end side of the shaft tube,
The mechanical pencil according to any one of claims 1 to 3, wherein the slider is provided with the core insertion hole, and the chamfered portion is provided on an end side of the core insertion hole.

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