JP2018083341A - mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical pencil which can avoid breakage of a writing lead when a high writing pressure is applied to the writing lead, which has a smooth writing feeling and which has excellent maintainability.SOLUTION: A mechanical pencil includes: a mouthpiece 52 in which a rear side is accommodated in a front cylinder member 45b and a writing lead 70 is inserted in a longitudinally movable manner; a cylindrical holding member 40b stored in the front cylinder member 45b; and a coil spring 55 disposed between a step part 52f of the mouthpiece 52 and a shoulder part 40d of the holding member 40b. The holding member 40b is press-fitted in the front cylinder member 45b so that an outer step 45j provided at the holding member 40b comes into contact with an inner step 45k provided at the front cylinder member 45b. In a rear cylinder member 45a, a female screw 45h provided at the rear cylinder member 45a is screwed to a male screw 45i provided at the front cylinder member 45b so that a front end part of the rear cylinder member 45a comes into contact with an inner surface of the shoulder part 40d of the holding member 40b. A fastening ring moves frontward/backward between a contact step part 40c of the holding member 40b and an inner flange 45d of the rear cylinder member 45a.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a mechanical pencil capable of writing by drawing a writing core by a predetermined amount from the tip of a base by a knocking operation or the like.

  Conventionally, when writing with a mechanical pencil, if a high writing pressure is applied to the writing core, there is a problem that the writing core exposed from the tip of the die is easily broken. When the writing pressure is constant, the writing core breaks down as the angle between the axial direction of the mechanical pencil barrel and the paper surface becomes smaller (so that the barrel is laid down), or the writing lead exposed from the tip of the base The longer the length is, the more conspicuous.

  With respect to such a problem, Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-123869) discloses that when a high writing pressure is applied to the writing core, the axial component of the writing pressure and the writing pressure are perpendicular to the axial direction. A mechanical pencil is described in which components are absorbed by different mechanisms to reduce breakage of the writing core.

Specifically, in the mechanical pencil of Patent Document 1, a base is supported by a shaft cylinder via an elastic body (coil spring), and the base has a cam slope whose diameter gradually decreases toward the rear in the axial direction. ing. Further, the shaft tube is formed with a pressing portion that presses the cam inclined surface forward in the axial direction. With such a configuration, due to the component perpendicular to the axial direction of the pen pressure (force in the outer direction of the shaft cylinder diameter), the cam inclined surface of the base is pressed forward in the axial direction by the pressing portion of the shaft cylinder, and the shaft cylinder The base slides forward from the tip of the tip. Thereby, the length of the writing core exposed from the front-end | tip of a nozzle | cap | die is reduced.
Furthermore, the mechanical pencil of Patent Document 1 is relatively moved in the axial direction in a state where the lead feeding unit for feeding out the writing lead is urged forward in the axial direction by the elastic body (coil spring) (the tip direction of the base in the axial direction). It is supported by the shaft cylinder as possible. The core feeding unit including the writing core moves relative to the axial tube rearward in the axial direction, whereby the axial component of the writing pressure is absorbed. As a result, the length of the writing core exposed from the tip of the base is further reduced, and the breakage of the writing core is reduced.

JP2015-123689

  In the mechanical pencil described in Patent Document 1, when a high writing pressure is applied to the writing core, the base is stretched all at once over the maximum length (stroke) that allows the base to slide forward with respect to the barrel. It is designed to slide (jump out).

On the other hand, the present inventor has developed a configuration in which the writing core slides backward with respect to the base when a high writing pressure is applied to the writing core, and such a configuration has a smoother writing feeling. It was confirmed that there are many users who feel that.
Furthermore, in order to reduce the breakage of the writing core, it was confirmed that it is important to stabilize the length of the writing core that is fed out by a single feeding operation. Thus, the user can recognize the approximate length that the writing core protrudes by the number of times the writing core is drawn out, and can prevent the writing core from protruding long and being easily broken. In particular, with a mechanical pencil, the user needs to perform maintenance when the writing core breaks in the lead feeding unit. Even in such a case, the user who disassembles the lead feeding unit can perform a single feeding operation. It is important to be able to assemble the lead feeding unit so that the length of the writing lead drawn out at is the same as before disassembly.

  The present invention is based on the above knowledge, and its purpose is to avoid breakage of the writing core when a high writing pressure is applied to the writing core, and to maintain a smooth writing feeling and maintenance. It is to provide a mechanical pencil with excellent properties.

The present invention
“1.
A lead feeding unit for feeding out a writing core, wherein a rear region is supported in the shaft tube so that a front region can be flexibly deformed or tilted in the shaft tube;
An overhang provided on the outer peripheral surface of the front region of the lead feeding unit;
A projecting portion provided on an inner peripheral surface in the axial direction rearward of the projecting portion of the shaft cylinder;
A stretchable elastic body disposed in a compressed state between the protruding portion and the protruding portion;
With
The lead feeding unit is
A core pipe extending in the axial direction of the shaft cylinder in the shaft cylinder, a connector provided at a front end portion of the core pipe, a chuck fixed to the front end portion of the connector, and a front region of the chuck A fastening ring that is externally fitted, a return spring that urges the connector axially rearward, a front cylinder member that is provided with a pressed portion on the outer peripheral surface, and a rear cylinder member that is provided with the protruding portion,
A base that is accommodated in the front cylinder member so that the writing core can be moved back and forth, a cylindrical holding member that is accommodated in the front cylinder member, a step portion of the base, and a shoulder portion of the holding member A coil spring disposed between,
Have
The holding member is press-fitted and fixed to the front cylinder member such that an outer stage provided on the holding member abuts on an inner stage provided on the front cylinder member,
In the rear cylinder member, a female screw provided in the rear cylinder member is screwed into a male screw provided in the front cylinder member so that a front end portion of the rear cylinder member abuts on an inner surface of a shoulder portion of the holding member. ,
The fastening ring moves back and forth between the contact step of the holding member and the inner flange of the rear cylinder member,
The shaft tube has a pressing portion in a front region,
At least one of the pressing portion and the pressed portion is a tapered surface that gradually increases in diameter toward the rear in the axial direction,
Before the front region of the core feeding unit is bent or deformed or tilted in the shaft cylinder, the pressing portion and the pressed portion are in contact with each other, and the front region of the core feeding unit is in the shaft tube. The mechanical pencil according to claim 1, wherein the pressing portion moves the pressed portion relative to the axial tube rearward in the axial direction when bending or tilting.
2. 2. The overhang according to claim 1, wherein the overhanging portion is a circular flange, and the flange has a plurality of radially-arranged groove portions that are open outward and rearward, and has a larger diameter than the elastic body. mechanical pencil. Is.

  According to the present invention, when a high writing pressure is applied to the writing core, the front region of the core feeding unit is tilted in the shaft cylinder by a component perpendicular to the axial direction of the writing pressure. As a result, the lead feeding unit including the writing lead is moved relative to the axial tube in the axial direction against the urging force of the elastic body, thereby reducing the length of the writing lead exposed from the tip of the base. The Further, the writing unit is exposed from the tip of the base by the axial component of the writing pressure, in which the lead feeding unit including the writing lead is further moved relative to the axial cylinder in the axial direction against the urging force of the elastic body. The length of the wick is further reduced. As a result, breakage of the writing core is avoided when a high writing pressure is applied to the writing core. In addition, at this time, the die is not moved relative to the axial forward in the axial direction (jumps out), but the lead feeding unit including the writing core is relatively moved axially rearward with respect to the die, The length of the writing core exposed from the base is reduced. As a result, a mechanical pencil with a smooth writing feel can be provided.

  When the writing core is broken in the base, the front cylindrical member and the rear cylindrical member in the core feeding unit can be unscrewed to remove the broken writing core in the base, and the shoulder of the holding member 40b. By tightening the female screw 45h provided on the rear cylinder member 45a with the male screw 45i provided on the front cylinder member 45b so that the front end of the rear cylinder member 45a contacts the inner surface of the portion 40d, The distance moved back and forth between the abutting step 40c of the holding member 40b and the inner flange 45d of the rear cylinder member 45a can be made the same as before the disassembly, and the user can draw out by one feeding operation. The lead feeding unit can be easily assembled so that the lead length is the same as before disassembly.

  The mechanical pencil of the present invention is provided in a tip region of the lead feeding unit, and includes a base that can move relative to the lead feeding unit in the axial direction of the shaft cylinder, and the lead feeding unit has a front end formed by the base. A core feeding unit main body surrounded by a portion, and a holding member that holds the base in the core feeding unit main body in a state that prevents the base from being detached. When the mechanical pencil is assembled or disassembled, the base is undesirable. In addition, the workability is good because it does not fall out of the lead feeding unit.

  Further, the overhanging portion is formed into a circular flange, and a plurality of radially-arranged groove portions are formed on the flange so that a user has a larger diameter than the elastic body. When the front tube member and the rear tube member are screwed together, or when the screw is unscrewed, the user picks from the rear of the flange, so that force is applied so that the front tube member and the rear tube member approach each other. In this state, a force in the rotational direction is applied, so that the front pencil member and the rear cylinder member can be easily attached and detached, and a mechanical pencil with higher maintainability can be obtained.

  In addition, Preferably, the said to-be-pressed part of the said core supply unit is the said taper surface, The said taper surface has either angle between 20 degrees-60 degrees with respect to the axial direction of the said axial cylinder. The elastic body is a coil spring, and a load required to move the pressed portion relative to the shaft cylinder in the axial rearward direction against the urging force of the coil spring is 0.5N to Any value between 8N.

  In this case, when a high writing pressure is applied to the writing core, the core feeding unit including the writing core can be reliably moved relative to the shaft cylinder in the axially rear direction, so that breakage of the writing core is avoided. On the other hand, when an appropriate writing pressure is applied to the writing lead, the lead feeding unit including the writing lead is not substantially moved rearward in the axial direction with respect to the shaft tube, so that the writing quality is not impaired.

  According to the present invention, when a high writing pressure is applied to the writing core, breakage of the writing core can be avoided, and a mechanical pencil with a smooth writing feeling and excellent maintainability can be provided. .

It is a schematic longitudinal cross-sectional view of the mechanical pencil of embodiment of this invention. It is a schematic longitudinal cross-sectional view of the front area | region of the mechanical pencil of FIG. 1 when the writing pressure is not applied to the writing core. It is a schematic longitudinal cross-sectional view of the front area | region of the mechanical pencil of FIG. 1 in case writing pressure is applied to the writing core. It is a perspective view of the components of the lead feeding unit in the mechanical pencil of FIG. It is a perspective view of the lead feeding unit in the mechanical pencil of FIG. It is a perspective view of the lead feeding unit which shows the state which removes the writing lead broken in the nozzle | cap | die. It is a perspective view of the state where the screwing of the lead feeding unit was removed.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic longitudinal sectional view of the mechanical pencil 100 according to the first embodiment of the present invention. FIG. 2 shows the mechanical pencil 100 shown in FIG. 1 when no writing pressure is applied to the writing core 70. FIG. 3 is a schematic vertical cross-sectional view of the front region, and FIG. 3 is a schematic vertical cross-sectional view of the front region of the mechanical pencil 100 of FIG. 1 when a writing pressure is applied to the writing core 70.

  As shown in FIGS. 1 to 3, the mechanical pencil 100 according to the present embodiment includes a shaft cylinder 10 and a writing core 70 that is supported in the shaft cylinder 10 and whose front region is tiltable in the shaft cylinder 10. A lead feeding unit 40 for feeding. The shaft cylinder 10 according to the present embodiment is made of polycarbonate, and includes a rear shaft 20 and a front shaft 30 whose rear region is fixed (screwed) to a front region of the rear shaft 20.

  The core feeding unit 40 according to the present embodiment is fixed to a polypropylene core pipe 41 extending in the axial direction of the shaft tube 10 inside the shaft tube 10 and a front end portion of the core pipe 41 via a connector 49. A brass chuck 43, a brass fastening ring 42 fitted in the front area of the chuck 43, an outer cylinder 45 surrounding the chuck 43, and a core pipe 41 attached to the outer cylinder 45 in the axial rearward direction. Return spring 44.

  Specifically, as shown in FIGS. 2 and 3, the outer cylinder 45 has a flange 45 c (projecting portion) that supports the chuck 43 on the inner peripheral surface of the front region and projects to the outer peripheral surface of the rear region. It has a rear cylinder member 45a and a front cylinder member 45b that is screwed into the front end region of the rear cylinder member 45a and extends forward in the axial direction beyond the front end portion of the chuck 43. Further, the rear cylinder member 45 a has an inner flange 45 d at the front end portion, and a return spring 44 is disposed in a compressed state between the inner flange 45 d and the connector 49. The core pipe 41 is urged rearward in the axial direction. In this state, the chuck 43 is clamped by the fastening ring 42 so as not to retract the writing core 70.

  Further, the shaft tube 10 (rear shaft 20) has a protruding portion 21 on the inner peripheral surface at the rear in the axial direction with respect to the flange 45c of the outer tube 45, and is expanded and contracted between the protruding portion 21 and the flange 45c. A possible coil spring 60 is arranged in a compressed state. With such a configuration, the lead feeding unit 40 including the writing lead 70 can move relative to the axial tube 10 in the axially rearward direction against the urging force of the coil spring 60.

  The outer diameter of the flange 45c is larger than the outer diameter of the coil spring 60, and the inner diameter of the rear region of the front shaft 30 is larger than the outer diameter of the flange 45c. And a gap is formed between the outer peripheral surface of the flange 45c. As a result, the tilting of the lead feeding unit 40 with respect to the shaft tube 10 is allowed. The front end edge 45e of the flange 45c is in contact with the rear end of the rear cylinder member 45a. When the core feeding unit 40 is tilted, the circular front end edge 45e of the flange 45c is brought to the inner peripheral surface of the front shaft 30. Abut. Further, the flange 45c is formed with a plurality of radial grooves 45f that are open outward and rearward. Since the grooves 45f are not on the front end edge 45e side of the flange 45c, they are formed on the inner peripheral surface of the front shaft 30. On the other hand, the flange 45c can come into uniform contact.

A brass cap 52 is attached to the tip region of the lead feeding unit 40. The base 52 of the present embodiment is disposed in the tip region of the lead feeding unit 40 and can be moved relative to the lead feeding unit 40 in the axial direction of the barrel 10. As shown in FIGS. 2 and 3, the base 52 includes a cylindrical front region 52 a that guides the writing core 70, and a sleeve-like rear region 52 b having a larger diameter than the front region 52 a. . The rear region 52b has a front small diameter portion 52c and a rear large diameter portion 52d, and the small diameter portion 52c and the large diameter portion 52d are connected by a shoulder 52e.
The base 52 has a lead feeding unit main body in a state of being prevented from being detached and slidable in the axial direction of the shaft tube 10 by the front tube member 45b and a cylindrical holding member 40b fitted and fixed to the front tube member 45b. It is attached to the tip region of 40a. Specifically, as shown in FIGS. 2 and 3, the front cylindrical member 45b includes a cylindrical main body 45g surrounding the rear region 52b of the base 52, and a female screw formed in the rear end region of the main body 45g. Part 45h. The female screw portion 45h is screwed into a male screw portion 45i formed in the front end region of the rear cylinder member 45a, and the front cylinder member 45b, the rear cylinder member 45a, and the holding member 40b are integrally configured. . The holding member 40 b has an abutting step portion 40 c that restricts the forward movement of the fastening ring 42 in the middle on the inner peripheral surface in the axial direction of the fastening ring 42.
When the holding member 40b is fitted and fixed to the front cylinder member 45b, the outer stage 45j provided on the holding member 40b is brought into contact with the inner stage 45k provided on the front cylinder member 45b. Further, when the rear cylinder member 45a is screwed into the front cylinder member 45b during maintenance, the abutting step is performed by bringing the front end portion of the rear cylinder member 45a into contact with the inner surface of the shoulder portion 40d of the holding member 40b. The distance between the portion 40c and the inner collar 45d is constant, and as a result, when performing the feeding operation by moving the fastening ring 42 back and forth, the writing core can be fed out by a certain amount without changing before and after the maintenance.

In this embodiment, the front end edge 45e of the flange 45c and the rear end of the front cylinder member 45b are provided so that the front end of the rear cylinder member 45a can come into contact with the inner surface of the shoulder 40d of the holding member 40b. A gap S is provided between them.
A structure is also conceivable in which the front end edge 45e of the flange 45c and the rear end of the front cylinder member 45b are brought into contact with each other without providing the gap S to complete the screwing of the female screw portion 45h and the male screw portion 45i. In this case, it is necessary to provide a gap between the front end portion of the rear cylinder member 45a and the inner surface of the shoulder portion 40d of the holding member 40b, and the base 52, the holding member 40b, the front cylinder member 45b, the rear cylinder member 45a, etc. Since the dimensional accuracy of many members will affect, it is not preferable.
The base 52 is held so that the rear region 52b is slidable in the axial direction inside the front cylinder member 45b, and an undesired drop-off from the front cylinder member 45b is prevented. In this state, an expandable / contractable coil spring 55 is disposed in a compressed state between a stepped portion 52f formed at the center of the enlarged diameter portion 52d of the base 52 and the shoulder portion 40d of the holding member 40b. The front end of the shaft tube 10 (front shaft 30) is an opening having a flange 33, and a front region 52a of the base 52 projects forward from the opening. With such a configuration, even when the lead feeding unit 40 is moved relatively rearward in the axial direction with respect to the shaft tube 10, the contact between the base 52 and the inner flange 33 of the shaft tube 10 is caused by the elastic force of the coil spring 55. The contact state is maintained. Accordingly, the length of the writing core 70 exposed from the front end portion of the base 52 is reduced when the core feeding unit 40 including the writing core 70 is relatively moved rearward in the axial direction with respect to the shaft cylinder 10. It has become.

  The front cylinder member 45b has a pressed portion 53 at the front end. The pressed portion 53 of the present embodiment is configured as a tapered surface having an angle of 40 ° with respect to the axial direction of the shaft tube 10. Moreover, the axial cylinder 10 (front axis | shaft 30) has the press part 32 projected over the internal peripheral surface in the front area | region. In the present embodiment, as shown in FIG. 2, before the lead feeding unit 40 tilts, the pressing portion 32 and the pressed portion 53 are in contact with each other. As shown in FIG. 3, when the lead feeding unit 40 tilts, the pressing portion 32 moves the pressed portion 53 relative to the shaft tube 10 in the axial direction rearward. In the present embodiment, the spring constant of the coil spring 60 is 1600 N / m, and the pressed portion 53 (tapered surface) is moved relative to the shaft tube 10 in the rearward direction against the urging force of the coil spring 60. The load required for this is 5.0N. The spring constant of the coil spring 55 is 1000 N / m. By setting the biasing force of the coil spring 55 smaller than the biasing force of the coil spring 60, the outer cylinder 45 shown in FIG. The contact state between the base 52 and the inner flange 33 of the shaft tube 10 is maintained until the tube 45 starts moving.

  As shown in FIG. 1, the lead feeding unit 40 further includes a knock portion 48 that is attached to the rear end of the lead pipe 41 and presses the lead pipe 41 forward in the axial direction against the outer cylinder 45. doing. The knock portion 48 of the present embodiment has a sleeve portion 48a that is fitted on the rear end region of the core pipe 41 in the axially forward direction, so that the cylindrical eraser 80 can be removed in the axially rearward direction. It has a holder portion 48b for holding. The internal space of the sleeve portion 48a and the internal space of the holder portion 48b are communicated by an opening. Thus, by removing the eraser 80 from the holder portion 48b, the writing core 70 can be put into the core holder 41 from the opening. A dome-shaped knob 81 that covers the back of the eraser 80 is detachably fitted to the holder portion 48b.

  Furthermore, in the present embodiment, the head crown 23 is fixed to the rear end region of the rear shaft 20. A step portion 23 a facing rearward in the axial direction is formed on the inner peripheral surface of the head crown 23. A flange portion 48c is formed on the outer periphery of the holder portion 48b, and an expandable / contractable spring 48d is disposed in a compressed state between the flange portion 48c and the stepped portion 23a.

  Next, the operation of the mechanical pencil 100 according to the embodiment of the present invention will be described.

  First, prior to writing on the paper, if necessary, the knob 81 and the eraser 80 are removed from the holder portion 48b, and the writing core 70 is formed through an opening that connects the sleeve portion 48a and the holder portion 48b. It is put into the core pipe 41. Then, the eraser 80 and the knob 81 are attached to the holder portion 48b, and the knock portion 48 (knob 81) is pressed (knocked) forward in the axial direction with the front end of the base 52 directed downward. As a result, the core pipe 41, the connector 49, the chuck 43 and the fastening ring 42 are advanced against the urging force of the return spring 44. In the middle of this forward movement, only the fastening ring 42 comes into contact with the contact step portion 40 c formed on the front cylinder member 45 b of the outer cylinder 45. As a result, the fastening ring 42 is removed rearward from the chuck 43, the chuck 43 is released, and the writing core 70 is fed out. At the time of pressing (knocking), an appropriate resistance is provided by the biasing force of the spring 48d disposed between the flange portion 48c of the knock portion 48 and the step portion 23a of the head crown 23.

  When the pressing state of the knock portion 48 (knob 81) is released, the core pipe 41 is retracted together with the chuck 43 by the urging force of the return spring 44. Along with this, the fastening ring 42 is fitted again to the front region of the chuck 43, and the chuck 43 is fastened. Thereby, the writing core 70 is pinched so as not to retreat, and the state where the writing core 70 is extended is maintained. Then, by repeating this series of pressing operations as appropriate, the writing core 70 is exposed (drawn out) for a desired length from the tip of the base 52 (see FIG. 2). Then, the front shaft 30 is gripped by the user, and writing is performed by moving the shaft tube 10 as desired while bringing the writing core 70 into contact with the paper surface.

  In writing, the shaft tube 10 is generally held so that the axial direction forms an acute angle with respect to the paper surface (see FIGS. 2 and 3). For this reason, a writing pressure including a component perpendicular to the axial direction of the shaft cylinder 10 and a component in the axial direction is applied to the writing core 70. When a high writing pressure is applied to the writing core 70 during writing, the mechanical pencil 100 of the present embodiment absorbs a component perpendicular to the axial direction of the writing pressure and a component in the axial direction, respectively, from the tip of the base 52. The breakage of the exposed writing core 70 is avoided.

  Specifically, as shown in FIG. 3, the front region of the core feeding unit 40 is tilted by a component perpendicular to the axial direction of the writing pressure, and the pressed portion 53 of the front cylinder member 45 b is pressed by the pressing portion 32 of the front shaft 30. Is pushed rearward in the axial direction of the barrel 10. As a result, the lead feeding unit 40 including the writing lead 70 is moved relative to the axial tube 10 in the axially rearward direction against the urging force of the coil spring 60. On the other hand, the base 52 is biased forward in the axial direction with respect to the holding member 40 b by the coil spring 55, and therefore is not moved relative to the axial tube 10 in the rearward direction in the axial direction. As a result, the length of the writing core 70 exposed from the tip of the base 52 is reduced.

  At the same time, the writing core 70 can be pressed rearward in the axial direction against the shaft tube 10 by the axial component of the writing pressure. As a result, the lead feeding unit 40 including the writing lead 70 is further moved relative to the rear in the axial direction against the urging force of the coil spring 60. That is, the length of the writing core 70 exposed from the tip of the base 52 can be further reduced, and breakage of the writing core 70 can be avoided.

  When the writing pressure applied to the writing core 70 is weakened, the core feeding unit 40 including the writing core 70 is pushed back axially forward with respect to the shaft tube 10 by the biasing force of the coil spring 60. As a result, the initial state (see FIG. 2) is restored.

  According to the present embodiment as described above, when a high writing pressure is applied to the writing core 70, the front region of the core feeding unit 40 is tilted in the shaft tube 10 by a component perpendicular to the axial direction of the writing pressure. The As a result, the lead feeding unit 40 including the writing lead 70 is moved relative to the axial tube 10 in the axial direction against the urging force of the coil spring 60, so that the writing lead 70 exposed from the tip of the base 52 is exposed. Length is reduced. Further, due to the axial component of the writing pressure, the lead feeding unit 40 including the writing lead 70 is further moved relative to the axial tube 10 in the axial direction against the urging force of the coil spring 60, and from the tip of the base 52. The length of the exposed writing core 70 is further reduced. For these reasons, when a high writing pressure is applied to the writing core 70, breakage of the writing core 70 is avoided. Further, at this time, the base 52 is not moved relative to the axial tube 10 in the axial direction forward (jumps out), but the lead feeding unit 40 including the writing core 70 is moved relative to the base 52 in the axial direction rearward. As a result, the length of the writing core 70 exposed from the base 52 is reduced. For this reason, when the tip of the base 52 comes into contact with the paper surface, the length of the writing core 70 exposed from the base 52 is quickly increased by the biasing force of the coil spring 60 only by slightly reducing the writing pressure. Therefore, the catch between the tip of the base 52 and the paper surface can be quickly eliminated.

  Next, a state in which the writing core 70 broken in the base 52 of the mechanical pencil 100 according to the embodiment of the present invention is removed will be described.

As shown in FIGS. 6 and 7, the mechanical pencil 100 according to the present embodiment can expose the lead feeding unit 40 by releasing the screwed state of the rear shaft 20 and the front shaft 30. Further, as shown in FIG. 5, the lead feeding unit 40 releases the writing lead broken inside the base 52 (holding member 40b) by releasing the screwed state of the front tube member 45b and the rear tube member 45a. Can be removed. In the lead feeding unit 40 of the present embodiment, a plurality of radial grooves 45f that are open outward and rearward are formed in the flange 45c of the rear cylinder member 45a. Therefore, as shown in FIG. When the cylindrical member 45b and the rear cylindrical member 45a are screwed together or unscrewed, the user picks from the rear side of the flange 45c. As a result, as indicated by arrows X and -X in FIG. A force is applied so that the front cylinder member 45b and the rear cylinder member 45a approach each other. In this state, a force in the rotational direction indicated by the arrow Z and the arrow -Z is applied, so that the female screw of the front cylinder member 45b It became easy to attach and detach the part 45h and the male screw part 45i of the rear cylinder member 45a, and a mechanical pencil with high maintainability could be obtained.
Further, during the maintenance, when the rear cylinder member 45a is screwed into the front cylinder member 45b, the front end portion of the rear cylinder member 45a is brought into contact with the inner surface of the shoulder portion 40d of the holding member 40b. Since the distance between the portion 40c and the inner flange 45d is constant, when the fastening ring 42 is moved back and forth to perform the feeding operation of the writing core 70, the writing core 70 is fed out by a certain amount without changing before and after maintenance. I was able to.

DESCRIPTION OF SYMBOLS 10 Shaft cylinder 20 Rear axis | shaft 21 Projection part 23 Crown 23a Step part 30 Front shaft 32 Press part 33 Collar part 40 Core feeding unit 40a Core feeding unit main body 40b Holding member 40c Contacting step part 40d Shoulder part 41 Core pipe 42 Tightening ring 43 Chuck 44 Return spring 45 Outer cylinder 45a Rear cylinder member 45b Front cylinder member 45c Flange 45d Inner flange 45e Front edge 45f Groove part 45g Body part 45h Female thread part 45i Male thread part 45j Outer stage 45k Inner stage 49 Connector 48 Knock part 48a Sleeve Portion 48b holder portion 48c flange portion 48d spring 52 base 52a front region 52b rear region 52c small diameter portion 52d enlarged diameter portion 52e shoulder portion 52f stepped portion 55 pressed portion 55 coil spring 60 coil spring 70 writing core 80 eraser 81 knob 100 mechanical pencil

Claims (2)

A barrel,
A lead feeding unit for feeding out a writing core, wherein a rear region is supported in the shaft tube so that a front region can be flexibly deformed or tilted in the shaft tube;
An overhang provided on the outer peripheral surface of the front region of the lead feeding unit;
A projecting portion provided on an inner peripheral surface in the axial direction rearward of the projecting portion of the shaft cylinder;
A stretchable elastic body disposed in a compressed state between the protruding portion and the protruding portion;
With
The lead feeding unit is
A core pipe extending in the axial direction of the shaft cylinder in the shaft cylinder, a connector provided at a front end portion of the core pipe, a chuck fixed to the front end portion of the connector, and a front region of the chuck A fastening ring that is externally fitted, a return spring that urges the connector axially rearward, a front cylinder member that is provided with a pressed portion on the outer peripheral surface, and a rear cylinder member that is provided with the protruding portion,
A base that is accommodated in the front cylinder member so that the writing core can be moved back and forth, a cylindrical holding member that is accommodated in the front cylinder member, a step portion of the base, and a shoulder portion of the holding member A coil spring disposed between,
Have
The holding member is press-fitted and fixed to the front cylinder member such that an outer stage provided on the holding member abuts on an inner stage provided on the front cylinder member,
In the rear cylinder member, a female screw provided in the rear cylinder member is screwed into a male screw provided in the front cylinder member so that a front end portion of the rear cylinder member abuts on an inner surface of a shoulder portion of the holding member. ,
The fastening ring moves back and forth between the contact step of the holding member and the inner flange of the rear cylinder member,
The shaft tube has a pressing portion in a front region,
At least one of the pressing portion and the pressed portion is a tapered surface that gradually increases in diameter toward the rear in the axial direction,
Before the front region of the core feeding unit is bent or deformed or tilted in the shaft cylinder, the pressing portion and the pressed portion are in contact with each other, and the front region of the core feeding unit is in the shaft tube. The mechanical pencil according to claim 1, wherein the pressing portion moves the pressed portion relative to the axial tube rearward in the axial direction when bending or tilting.   The said overhang | projection part is a circular-shaped flange, The said flange is open | released outward and back, has a groove part arranged in multiple numbers radially, and is larger diameter than the said elastic body. mechanical pencil.

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