JP2018187790A - mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely avoid breakage of a writing core when a high writing pressure is applied to the writing core, and to adjust a situation in which the writing core operates when a load is applied to the writing core. Get a possible mechanical pencil. When the front region of a lead feeding unit bends, deforms, or tilts in a shaft cylinder, a weak coil spring is compressed until the shaft portion abuts on the inner shaft, and the pressed portion makes the pressed portion into the shaft cylinder. On the other hand, the shaft is moved relative to the rear in the axial direction, and after the shaft is in contact with the inner shaft, the strong coil spring is compressed, and the pressed portion moves the pressed portion to the rear in the axial direction with respect to the shaft cylinder. By operating the operating body provided on the cylinder, the inner shaft connected to the operating body moves back and forth, and the locking projection of the inner shaft is locked while moving back and forth in the locking groove of the regulating member, and is locked with the inner shaft. A mechanical pencil featuring a structure that expands and contracts the gap in the front-back direction with the shaft. [Selection diagram] Fig. 1

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.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 2015-123869 discloses a component of an axial direction of writing pressure and a component perpendicular to the axial direction of the writing pressure when a high writing pressure is applied to the writing core. A mechanical pencil is described that absorbs by different mechanisms to reduce breakage of the writing core.

Specifically, in the mechanical pencil of Patent Document 1, the base is supported by a shaft cylinder via an elastic body (spring), and the base gradually decreases in diameter toward the rear in the axial direction of the shaft cylinder. have. Further, the shaft cylinder is formed with a pressing portion that presses the cam inclined surface forward in the axial direction of the shaft cylinder. With such a configuration, the cam inclined surface of the base is pressed forward in the axial direction of the shaft cylinder by the pressing portion due to a component of the writing pressure in the direction orthogonal to the axial direction of the shaft cylinder (force in the outer direction of the shaft diameter). Then, the base slides forward (jumps out) from the tip of the shaft tube. Thereby, the length of the writing core exposed from the front-end | tip of a nozzle | cap | die is reduced.
Further, in the mechanical pencil of Patent Document 1, the core feeding unit for feeding out the writing core is urged forward in the axial direction by the elastic body (spring) (the front end direction of the base in the axial direction). Are supported by the shaft cylinder in a state of being relatively movable. Then, the core feeding unit including the writing core relatively moves rearward in the axial direction of the shaft cylinder, so that 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.

  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, as disclosed in International Publication No. 2017/002731, the applicant of the present application has a base attached to the shaft cylinder when a high writing pressure is applied to the writing core. We have developed a configuration that slides in the radial direction and the writing core slides backward with respect to the base. With such a mechanical pencil, breakage of the writing core can be effectively avoided, but it is also possible to set the situation in which the function operates according to the strength of the writing core or according to the user's preference. Mechanical pencils have been demanded.

Japanese Patent Laying-Open No. 2015-123689 International Publication No. 2017/002731

  The present invention is based on the above knowledge, and its purpose is to reliably avoid breakage of the writing core when a high writing pressure is applied to the writing core, and to load the writing core. An object is to obtain a mechanical pencil that allows a user to adjust a situation that is activated when the robot is hung.

The present invention
“Inside the barrel,
A lead feeding unit for feeding out a writing core, in which a rear region is supported in the shaft tube so that a front region is flexibly deformable or tiltable in the shaft tube;
The lead feeding unit has a base for holding a writing core, a base member through which the base is inserted, and a locking groove that is restricted in advancing and rotating with respect to the shaft tube and continues inward in the front-rear direction. A cylindrical regulating member, a weak coil spring disposed between the regulating member and the base member, and a cylindrical inner shaft having a locking projection inwardly locked in a locking groove of the regulating member; With
Between the regulating member and the shaft tube, a strong coil spring is provided,
Between the base member and the inner shaft, there is a shaft portion that extends rearward of the base member and has a front-rear direction gap between the base member,
The base member has a pressed portion on the outer peripheral surface,
The shaft tube has a pressing portion,
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 tube, the pressing portion and the pressed portion are in contact with each other,
When the front region of the core feeding unit is bent or deformed or tilted in the shaft tube, the weak coil spring is compressed until the shaft portion comes into contact with the inner shaft, and the pressing portion causes the pressed portion to be pressed. After moving relative to the shaft tube in the axial direction and the shaft portion abuts against the inner shaft, the strong coil spring is compressed, and the pressing portion causes the pressed portion to move relative to the shaft tube. To move it axially backward,
By operating the operating body provided on the shaft cylinder, the inner shaft connected to the operating body moves back and forth, and the locking projection of the inner shaft moves back and forth in the locking groove of the restricting member. A mechanical pencil having a structure in which a gap in the front-rear direction between the inner shaft and the shaft portion expands and contracts. 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 can be flexibly deformed or 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.

  The writing pressure is absorbed stepwise in this order by the weak coil spring that starts compressive deformation with a relatively small load and the strong coil spring that starts compressive deformation with a relatively large load. By optimizing the gap between the inner shaft and the shaft portion, the resistance feeling due to the urging force of the coil spring when the core feeding unit including the writing core is relatively moved axially rearward with respect to the shaft cylinder is optimized. be able to.

The cylindrical control member has a locking groove formed in a spiral groove extending in the front-rear direction, and the locking protrusion of the inner shaft is a locking protrusion that locks the locking groove, thereby rotating the operating body. Thereby, it can be set as the structure which expands / contracts the clearance gap of the front-back direction of an inner shaft and a shaft part. In this case, by gently forming the inclination angle of the spiral groove, the gap between the inner shaft and the shaft portion can be finely adjusted, and the locking projection moves in the front-rear direction with respect to the locking groove. Even when an external force is applied, the locked state is easily maintained. Note that a locking protrusion may be provided on the regulating member, and a locking groove may be provided on the inner shaft.
Furthermore, by forming the locking groove with a female screw having a continuous spiral in the front-rear direction and forming the locking projection with a male screw, the number of locations locked with each other increases, so that the locked state is stabilized. Can do.
Further, the locking groove of the restricting member is formed by continuously forming a plurality of recesses in the front-rear direction along the axis, and the spring property that can lock the locking protrusions of the inner shaft to the plurality of continuous recesses stepwise. It is also possible to have a convex portion. Alternatively, the inner surface of the locking groove of the restricting member is formed linearly with a material that generates frictional resistance by an elastomer or the like, and the locking protrusion of the inner shaft is formed slightly larger than the inner width of the locking groove, It is also possible for the locking projection to be locked with frictional resistance.
In these cases, it is possible to have a structure in which the front-rear direction gap between the inner shaft and the shaft portion is expanded and contracted by the front-rear operation of the operating body.

  Preferably, the pressed portion of the lead feeding unit is the tapered surface, and the tapered surface has any angle between 20 ° and 60 ° with respect to the axial direction of the shaft tube. The load required to move the pressed portion relative to the shaft cylinder in the axial rearward direction against the urging force of the weak coil spring is any value between 0.5N and 2.5N. And the load required to move the pressed portion relative to the shaft cylinder in the axially rearward direction against the urging force of the strong coil spring is any value between 3N and 8N. .

  According to the present invention, when a high writing pressure is applied to the writing core, breakage of the writing core can be surely avoided, and the user can adjust the operating condition when a load is applied to the writing core. A mechanical pencil that can be obtained can be obtained.

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 which shows the 1st state which operated the operation body. It is a schematic longitudinal cross-sectional view of the front area which shows the 2nd state which operated the operation body. It is a schematic longitudinal cross-sectional view of the front area | region of the mechanical pencil of FIG. 1 in the state in which the writing pressure is applied to the writing core.

  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 a mechanical pencil 1 according to an embodiment of the present invention, FIG. 2 is a schematic longitudinal sectional view of a front region showing a first state in which an operating body is operated, and FIG. FIG. 4 is a schematic longitudinal sectional view of the front region showing a second state in which the operating body is operated, and FIG. 4 is a front region of the mechanical pencil 1 in FIG. 1 in a state where writing pressure is applied to the writing core 70. It is a schematic longitudinal cross-sectional view.

  As shown in the figure, the mechanical pencil 1 according to the present embodiment is supported by the shaft tube 10 and the shaft tube 10, and the lead region 70 can be tilted within the shaft tube 10 to feed out the writing core 70. A feeding unit 40. 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, the outer cylinder 45 includes a rear cylinder 45a that supports the chuck 43 on the inner peripheral surface of the front area, and is fitted and fixed to the front end area of the rear cylinder 45a and extends forward in the axial direction beyond the front end portion of the chuck 43. And an extending front cylinder 45b.
A base member 51 is slidably disposed on the outer side of the outer cylinder 45, and a base 52 is slidably inserted in front of the base member 51.
The base member 51 has a pressed portion 53 at the front end.

Further, a retractable weak coil spring 60a is disposed behind the base member 51, and a retractable strong coil spring 60b is disposed behind the weak coil spring 60a in a compressed state.
The weak coil spring 60a and the strong coil spring 60b are connected via a cylindrical regulating member 61 that regulates the compression length of the weak coil spring 60a. The rear end of the strong coil spring 60b is in contact with the front end of the rear shaft 20, the front end of the strong coil spring 60b is in contact with the rear step portion 61a of the regulating member 61, and the front end of the regulating member 61 is the rear of the weak coil spring 60a. The front end of the weak coil spring 60 a is in contact with the rear end of the flange portion 45 c formed on the base member 51.
With such a configuration, the lead feeding unit 40 including the writing lead 70 can be moved relative to the axial tube 10 in the rearward direction against the biasing force of the weak coil spring 60a and the strong coil spring 60b. .
In the present embodiment, the spring constant of the weak coil spring 60a is 700 N / m, and the spring constant of the strong coil spring 60b is 1000 N / m.

The inner diameter of the rear region of the front shaft 30 is larger than the outer diameter of the flange portion 45c of the base member 51, and a gap is formed between the inner peripheral surface of the front shaft 30 and the outer peripheral surface of the flange portion 45c. Has been. As a result, the tilting of the lead feeding unit 40 with respect to the shaft tube 10 is allowed.
Further, the base 52 made of brass is attached to the tip region of the core feeding unit 40. The base 52 of the present embodiment is supported on a cylindrical base member 51 made of brass fixed to the front end region of the core feeding unit 40 so as to be relatively movable in the axial direction, and together with the base member 51, the base unit 50. Is configured.

  The base member 51 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 27.5 ° with respect to the axial direction of the shaft tube 10. Moreover, the axial cylinder 10 (front axis | shaft 30) has the press part 31 projected over the internal peripheral surface in the front area | region. In the present embodiment, the pressing portion 31 and the pressed portion 53 are in contact with each other before the lead feeding unit 40 is tilted. As shown in FIG. 4, when the lead feeding unit 40 tilts, the pressing portion 31 moves the pressed portion 53 relative to the axial tube 10 in the axially rearward direction.

  With the configuration as described above, in the present embodiment, a load necessary to move the pressed portion 53 (tapered surface) relative to the axial tube 10 in the axial rear direction against the urging force of the weak coil spring 60a. Is 2N, and the load required to move the pressed portion 53 (tapered surface) relative to the axial tube 10 in the axial rearward direction against the urging force of the strong coil spring 60b is 7N.

The base member 51 has an inner diameter of the rear region 51b smaller than an inner diameter of the front region 51a, and a step portion 54 is formed on the inner peripheral surface of the connection portion between the front region 51a and the rear region 51b. Yes.
A retractable spring 55 is disposed in a compressed state between the rear end portion of the rear region 52 b of the base 52 and the stepped portion 54 of the base member 51. A cylindrical gap is formed between the inner peripheral surface of the front region 51a and the outer peripheral surface of the core feeding unit 40, and the base 52 is inserted into this gap.

Specifically, as shown in FIGS. 1 and 2, the base 52 includes a pipe-shaped front region 52a for guiding the writing core 70, a sleeve-shaped rear region 52b having a diameter larger than that of the front region 52a, The rear region 52b is inserted into the cylindrical gap. Further, the shaft cylinder 10 (front shaft 30) has an inner flange 32 on the inner peripheral surface in the axial direction front side from the front end portion of the rear region 52 b of the base 52. The inner diameter of the shaft 30) is smaller than the outer diameter of the rear region 52 b of the base 52. That is, the inner collar 32 and the rear region 52b of the base 52 are in contact with each other, so that the relative movement of the base 52 in the axial direction relative to the shaft tube 10 is restricted, and the lead feeding unit 40 is prevented from coming off.
In this state, a retractable spring 55 is disposed in a compressed state between the rear end portion of the rear region 52 b of the base 52 and the stepped portion 54 of the base member 51. 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 state between the base 52 and the inner collar 32 of the shaft tube 10 is maintained. It has become. 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.

Further, as shown in FIG. 1, the core feeding unit 40 further includes a knock portion 46 that is attached to the rear of the core pipe 41 and presses the core pipe 41 axially forward against the outer cylinder 45. doing. The knock portion 46 of the present embodiment has a cylindrical rod-shaped member 46a disposed in the axially forward direction with a longitudinal gap S1 between the core pipe 41 and a circularly axially rearward portion. It has a holder part 46b that holds the column-shaped eraser 80 in a removable manner. The internal space of the rod-shaped member 46a and the internal space of the holder portion 46b are communicated with each other through an opening. Thus, by removing the eraser 80 from the holder portion 46b, the writing core 70 can be put into the core pipe 41 from the opening. A dome-shaped knob 81 that covers the back of the eraser 80 is detachably fitted to the holder portion 46b.
Further, the clearance S1 formed between the rod-shaped member 46a and the core pipe 41 can absorb the amount of movement when the core feeding unit 40 is moved backward with respect to the shaft tube 10.
In the present embodiment, the gap S1 is 2 mm.

A crown 23 is fixed to the rear end region of the rear shaft 20. A rotary operation body 24 is rotatably inserted inside the head crown 23. The knock portion 46 is inserted into the rotary operation body 24 so as to be movable back and forth.
On the inner peripheral surface of the rotary operation body 24, a step portion 24a facing rearward in the axial direction is formed. A flange portion 46c is formed on the outer periphery of the holder portion 46b, and an elastic spring 46d is disposed between the flange portion 46c and the step portion 24a in a compressed state.

An inner shaft 25 composed of a first inner shaft 25a and a second inner shaft 25b is arranged in front of the rotary operation body 24, and the female screw 24b provided on the front inner surface of the rotation operation body 24 and the first inner shaft 25b are arranged. A male screw 25c provided on the rear outer surface of the inner shaft 25a is fixed to be non-rotatable by screwing. The first inner shaft 25a and the second inner shaft 25b are integrated by locking a key groove 25d provided on the front inner surface of the first inner shaft 25a and a protrusion 25e provided on the rear outer surface of the second inner shaft 25b. Can be rotated and relatively moved back and forth.
A male screw 25f (locking projection) is provided on the front outer surface of the second inner shaft 25b, and is rotatably screwed with a female screw 61b (locking groove) provided on the restriction member 61.

A cylindrical shaft 71 is arranged in front of the regulating member 61. 1 is arranged between the front end of the second inner shaft 25b and the rear end of the base member 51, and the front end is in contact with the rear end of the base member 51. A gap S2 is formed between the front end of 25b and the rear end of the shaft portion 71.
Since the front end of the restricting member 61 is in contact with a step portion 30a provided on the inner surface of the front shaft 30 and is repelled by the strong coil spring 60b from the rear, forward movement and rotation are restricted. Therefore, when the rotary operation body 24 is rotated, the male screw 25b of the second inner shaft 25b is moved back and forth by the female screw 61b of the restricting member 61, and the front end of the second inner shaft 25b is the most axial portion. 2 from the first state shown in FIG. 2 far from the rear end of 71 to the second state shown in FIG. 3 in which the front end of the second inner shaft 25b is in contact with the rear end of the shaft portion 71 closest. The gap S2 can be expanded and contracted. The gap S2 in FIG. 1 is half the length of the first state and the second state.
In the present embodiment, the gap S2 is expanded and contracted in the range of 0 to 2 mm.
The mechanical pencil 1 shown in FIG. 2 has a gap S2 of 2 mm, the mechanical pencil 1 shown in FIG. 3 has a gap S2 of 0 mm, and the mechanical pencil 1 shown in FIG. 1 has a gap S2 of 1 mm. State.

  A step portion 25g facing rearward in the axial direction is formed on the outer peripheral surface of the first inner shaft 25a, and a stretchable spring 26 is compressed between the step portion 25g and the front end of the head crown 23. Is arranged in. Thereby, an appropriate resistance feeling is brought about during the rotation operation.

  Next, the operation of the mechanical pencil 1 according to the embodiment of the present invention will be described.

First, prior to writing on the paper surface, the knob 81 and the eraser 80 are removed from the holder portion 46b as necessary, and the writing core 70 is opened through an opening communicating the rod-like member 46a and the holder portion 46b. It is put into the core pipe 41. Then, the eraser 80 and the knob 81 are attached to the holder portion 46b, and the knock portion 46 (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 via the rod-shaped member 46a. In the middle of this forward movement, only the fastening ring 42 comes into contact with the contact step 45d formed on the front cylinder 45b 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 (knock operation), an appropriate resistance feeling is provided by the urging force of the spring 46d disposed between the flange portion 46c of the knock portion 46 and the step portion 24a of the rotary operation body 24.
In the present embodiment, 2 mm of the gap S1 between the rod-shaped member 46a and the core pipe 41 and a movement amount of 4 mm when the chuck 43 feeds the writing core 70 are required. Therefore, the knock stroke of the knock portion 46 is required. Requires 6 mm.

  When the pushing state of the knock portion 46 (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. 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 gripped so that its axial direction forms an acute angle with respect to the paper surface (see FIG. 4). 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 1 according to the present embodiment absorbs a component perpendicular to the axial direction of the writing pressure and a component in the axial direction from the tip of the base 52. The breakage of the exposed writing core 70 is avoided.

  Specifically, as shown in FIG. 4, the front region of the lead feeding unit 40 is tilted by a component perpendicular to the axial direction of the writing pressure, and the pressed portion 53 ( The taper surface is pressed rearward in the axial direction. As a result, the weak coil spring 60a that starts compressive deformation with a relatively small load is deformed first by the writing pressure, and the core breakage preventing function is activated in a state where a relatively weak load (2N) is applied to the writing core 70. I was able to. In addition, when a strong load is further applied to the writing core 70 from the state of FIG. 4 by writing, the shaft portion 71 moves rearward as the base member 51 moves rearward as shown in FIG. Then, since the rear end is in contact with the second inner shaft 25a, the weak coil spring 60a is not further compressed and deformed, and this time by the regulating member 61 screwed with the second inner shaft 25a. The compression deformation of the strong coil spring 60b is started, and at this time, the core breakage preventing function is operated in a state where a relatively strong load (7N) is applied to the writing core 70.

Furthermore, the situation when the core breakage prevention function operates will be described in detail with reference to FIG.
In the mechanical pencil 1, the front region of the lead feeding unit 40 is tilted by a component perpendicular to the axial direction of the writing pressure, and the pressed portion 53 (tapered surface) of the base member 51 is moved rearward in the axial direction by the pressing portion 31 of the front shaft 30. Pressed. As a result, the core feeding unit 40 including the writing core 70 is moved relative to the axial tube 10 in the axially rearward direction against the urging force of the weak coil spring 60a and the strong coil spring 60b.
On the other hand, since the base 52 is pressed forward in the axial direction with respect to the base member 51 by the urging force of the spring 55, it is not moved relative to the axial tube 10 rearward in the axial direction. As a result, the length of the writing core 70 exposed from the tip of the base 52 is reduced.

In addition, as described above, the mechanical pencil 1 of the present embodiment adjusts the clearance S2 between the front end of the second inner shaft 25b and the rear end of the shaft portion 71 by rotating the rotary operation body 24. be able to.
When the gap S2 is widened (see FIG. 2), the distance by which the weak coil spring 60a is compressed and deformed becomes long, so even when a relatively weak load (2N) is applied to the writing core 70, the core breakage preventing function When the clearance S2 is narrowed, the distance by which the weak coil spring 60a is compressed and deformed becomes short, so that the function of preventing the core breakage when a relatively weak load is applied to the writing core 70 becomes difficult. The core breakage prevention function can be activated with a relatively strong load (7N) set by the strong coil spring 60b. When the rotary operation body 24 is rotated and the gap S2 is set to 0 mm (see FIG. 3), since the weak coil spring 60a is not compressed and deformed, the function of preventing the core breakage with a relatively weak load is provided. It does not work, and the core breakage preventing function can be made to work when a relatively strong load (7N) set by the strong coil spring 60b is used.
Thereby, in the mechanical pencil 1 of the present embodiment, the user can set a situation where the core breakage prevention function is activated according to the strength of the writing core 70 or according to preference.

1 ... mechanical pencil,
10 ... shaft tube,
20 ... rear axle,
23 ... crown,
24 ... Rotating operation body, 24a ... Step part, 24b ... Female screw,
25 ... inner shaft, 25a ... first inner shaft, 25b ... second inner shaft, 25c ... male screw, 25d ... key groove, 25e ... projection, 25f ... male screw, 25g ... step,
26 ... Spring,
30 ... Front shaft, 30a ... Step portion, 31 ... Pressing portion, 32 ... Inner collar,
40 ... Core feeding unit,
41 ... Core pipe,
42 ... tightening ring,
43 ... Chuck,
44 ... Return spring,
45 ... outer cylinder,
45a ... rear cylinder,
45b ... front tube,
45c ... flange part,
45d ... contact step,
46 ... Knocking part,
46a ... rod-shaped member,
46b ... Holder part,
46c ... flange part,
46d ... Spring,
49 ... Connector,
50 ... Base unit,
51 ... Base member, 51a ... Front region, 51b ... Rear region,
52 ... Base, 52a ... Front region, 52b ... Rear region,
53 ... pressed part,
54 ... a step,
55 ... Spring,
60a ... weak coil spring,
60b ... Strong coil spring,
61 ... Restriction member, 61a ... Back step part, 61b ... Female screw,
70 ... writing core,
71 ... shaft part,
80 ... eraser,
81 ... Knob,
S1 ... Gap,
S2: A gap.

Claims (1)

Inside the barrel,
A lead feeding unit for feeding out a writing core, in which a rear region is supported in the shaft tube so that a front region is flexibly deformable or tiltable in the shaft tube;
The lead feeding unit has a base for holding a writing core, a base member through which the base is inserted, and a locking groove that is restricted in advancing and rotating with respect to the shaft tube and continues inward in the front-rear direction. A cylindrical regulating member, a weak coil spring disposed between the regulating member and the base member, and a cylindrical inner shaft having a locking projection inwardly locked in a locking groove of the regulating member; With
Between the regulating member and the shaft tube, a strong coil spring is provided,
Between the base member and the inner shaft, there is a shaft portion that extends rearward of the base member and has a front-rear direction gap between the base member,
The base member has a pressed portion on the outer peripheral surface,
The shaft tube has a pressing portion,
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 tube, the pressing portion and the pressed portion are in contact with each other,
When the front region of the core feeding unit is bent or deformed or tilted in the shaft tube, the weak coil spring is compressed until the shaft portion comes into contact with the inner shaft, and the pressing portion causes the pressed portion to be pressed. After moving relative to the shaft tube in the axial direction and the shaft portion abuts against the inner shaft, the strong coil spring is compressed, and the pressing portion causes the pressed portion to move relative to the shaft tube. To move it axially backward,
By operating the operating body provided on the shaft cylinder, the inner shaft connected to the operating body moves back and forth, and the locking projection of the inner shaft moves back and forth in the locking groove of the restricting member. A mechanical pencil having a structure in which a gap in the front-rear direction between the inner shaft and the shaft portion expands and contracts.

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