JP7241523B2 - Mechanical pencil unit, retractable writing instrument, and method for manufacturing mechanical pencil unit - Google Patents

Description

The present invention relates to a mechanical pencil unit constituting a refill for a mechanical pencil, a mechanical pencil, or the like, a retractable writing instrument equipped with the mechanical pencil unit, and a method for manufacturing the mechanical pencil unit.

Conventionally, in relation to this type of invention, for example, Patent Document 1 discloses a holding cylinder formed by connecting first to third cylinder parts, and a holding cylinder inserted through a front opening of the holding cylinder and extending forward from the front end of the holding cylinder. The holder is protruding toward the outside and supported so as to move back and forth with respect to the holding cylinder, a lead core feeding mechanism that forwards the lead core inserted into the holder, and the holder is held by the radial force applied from the lead core to the holder. A mechanical pencil unit is described which includes a movement direction changing mechanism for advancing the cylinder and the lead lead relative to each other, and a centrifugal delivery mechanism for delivering the lead lead clamped by the chuck portion by a predetermined operation. Then, it is possible to construct a retractable writing instrument by housing this mechanical pencil unit in the barrel.
According to this retractable writing instrument, the mechanical pencil unit is advanced by a predetermined operation, and in a state in which the holder at the front end of the mechanical pencil unit protrudes from the opening at the front end of the barrel, the lead core protruding from the holder is radially moved. When the force is applied, the holder advances relative to the holding cylinder and the lead core, so that the lead core can be covered and protected by the holder.

JP 2017-159579 A

By the way, in the prior art, there are cases where a plurality of cylindrical members are connected back and forth in order to construct a complicated mechanism such as the motion direction changing mechanism or the lead lead feeding mechanism. For example, in the mechanical pencil unit, the second cylindrical portion and the third cylindrical portion are connected by press-fitting. Such a press-fit connection structure of two cylindrical members can be applied to other parts of the mechanical pencil unit.
However, when two relatively slim and thin cylindrical members that are in close proximity or sliding contact with the outer peripheral surface of the lead core, such as a member that supports the base end of the chuck portion, are connected by press-fitting, the There is a risk that the cylindrical member, which is on the outside during press-fitting, may be damaged by tensile force in the circumferential direction.

In view of such problems, the present invention comprises the following configurations.
A mechanical pencil unit that draws out a lead lead by a predetermined operation, comprising a first tubular member and a second tubular member that are annularly connected to or in contact with an outer peripheral surface of the lead lead, One tubular member has a plurality of locking protrusions spaced in the circumferential direction on its inner peripheral surface, and the second tubular member is made of a material harder than the first tubular member. and has a fitting protrusion at a position where it is inserted into the first cylindrical member and has passed over the locking protrusion , and the first cylindrical member is a chuck part that clamps a lead core. A mechanical pencil unit, which is a member for supporting a base end side, wherein the second tubular member is connected to the rear side of the first tubular member.

INDUSTRIAL APPLICABILITY Since the present invention is configured as described above, it is possible to effectively prevent deformation and breakage even when a relatively thin cylindrical member that is in close proximity or sliding contact with the outer peripheral surface of the lead core is constructed from two parts. can be done.

1 is a cross-sectional view showing an example of a mechanical pencil unit according to the present invention; FIG. An example of the 1st cylindrical member is shown, (a) is a full sectional view, (b) is the figure seen from the back side. An example of a second cylindrical member is shown, (a) is a view seen from the front side, and (b) is a half cross-sectional view. (a) to (c) sequentially show states in which the second tubular member is connected to the first tubular member, the first tubular member being a full cross section, and the second tubular member being a side view. is. It is an internal structure diagram showing an example of a writing instrument equipped with the same mechanical pencil unit.

The present embodiment discloses the following features.
A first feature is a mechanical pencil unit that draws out a lead lead by a predetermined operation, in which a first tubular member and a second tubular member are connected back and forth in an annular proximity to or in contact with the outer peripheral surface of the lead lead. a first tubular member having a plurality of circumferentially spaced locking projections on an inner peripheral surface thereof; It is made of a hard material, and has a fitting protrusion that is inserted into the first cylindrical member and has a fitting protrusion that has passed over the locking protrusion (see FIGS. 1 to 4).
According to this configuration, when the overriding fitting projection rides over the plurality of locking projections, each locking projection is partially deformed, so that the entire first tubular member is deformed so as to expand in diameter. You can prevent it from getting damaged.

A second characteristic is that the first cylindrical member is made of a synthetic resin material and the second cylindrical member is made of a metal material as a specific preferred mode.

A third feature is that the overriding fitting projection is formed in an annular shape in order to maintain a higher degree of circularity (see FIG. 3).

A fourth feature is that, in order to maintain a high degree of circularity particularly during assembly work, the plurality of the plurality of tubular members are arranged closer to the second tubular member than the locking protrusions on the inner peripheral surface of the first tubular member. A cylindrical guide surface having an inner diameter larger than the tip inner diameter of the locking protrusion is provided (see FIGS. 2 and 4).

A fifth characteristic is that, as a preferred specific mode, the first tubular member is a member that supports the base end side of the chuck portion that clamps the lead core, and the second tubular member is the first tubular member. It is connected to the rear side of the member (see Figure 1).

A sixth feature is that the retractable writing instrument is provided with the mechanical pencil unit (see FIG. 5).

A seventh feature is the manufacturing method of the mechanical pencil unit, wherein the second cylindrical member is inserted into the first cylindrical member, and the locking protrusion is caused to climb over the overriding fitting protrusion. (See FIG. 4).

<Specific embodiment>
Next, specific embodiments having the above characteristics will be described in detail with reference to the drawings. In this specification, the axial direction means the direction in which the center line of the holding cylinder 10 extends. Further, "front" means one side in the axial direction and the direction in which the lead core is drawn out. Also, "rear" means the side opposite to the one side.

The mechanical pencil unit 1 shown in FIG. 1 includes a holding barrel 10, a lead lead feeding mechanism M1 supported in the holding barrel 10, a lead tank portion 60 penetrating through the rear end side of the holding barrel 10, A movement direction changing mechanism M2 is provided to advance the holder 20 relative to the lead core x by a radial force component applied to the lead core x.

According to the illustrated example, the holding tube 10 is concentrically connected to the first tube portion 11, which is internal so that the holder 20 protrudes forward, and the rear end side of the first tube portion 11. The second tubular portion 12 and the third tubular portion 13 concentrically connected to the rear end side of the second tubular portion 12 are integrally tubular. A part or all of these cylindrical portions 11, 12, 13 can be integrated.

The lead lead feeding mechanism M1 includes a lead breaker 30 that is held in the holding cylinder 10 and is elastically and loosely pressed against the outer peripheral surface of the lead core x, a chuck part 40 that advances and retreats behind the lead breaker 30, A clutch ring 41 annularly fitted to the chuck portion 40 , a substantially cylindrical clutch receiver 42 that receives the clutch ring 41 from the rear side, and first and second cylindrical portions that support the rear end side of the chuck portion 40 . and members 43,44.
The lead lead feeding mechanism M1 feeds out the lead core x clamped by the chuck part 40 by forward and backward movement transmitted from the lead tank part 60. As shown in FIG. Further, the lead lead feeding mechanism M1 moves the lead x and the chuck part 40 together with the lead x and the first and second leads when an urging force stronger than a preset writing pressure is applied to the lead x clamped by the chuck part 40 . , the tubular members 43, 44, etc. are retracted.

The core breaker 30 is formed in a substantially cylindrical shape from an elastic material such as elastomer resin or synthetic rubber, and its inner peripheral surface is in loose pressure contact with the outer peripheral surface of the lead core x.

The chuck portion 40 is formed by integrally connecting a plurality of long pieces arranged at intervals in the circumferential direction at the rear end side, and elastically deflecting the plurality of long pieces radially inward. At this time, the lead core x is held between the claws on the front end side of these elongated pieces.

The clutch ring 41 is engaged with the clamped chuck portion 40, and when moved forward together with the chuck portion 40, the clutch ring 41 comes into contact with the stepped portion on the inner surface of the holding cylinder 10 and comes off the chuck portion 40, thereby releasing the front end side of the chuck portion 40. . As the chuck portion 40 and the clutch ring 41, those having known structures can be used.

The clutch receiver 42 is provided so as to move back and forth within the holding cylinder 10 by a predetermined amount.

A first biasing member 51 , a second biasing member 52 and a third biasing member 53 are provided inside, outside and behind the clutch receiver 42 .

The first biasing member 51 faces the lead tank portion 60 and biases the clutch receiver 42 forward with a biasing force stronger than a preset normal writing pressure.

The second biasing member 52 is a compression coil spring whose biasing force is greater than that of the holder biasing member 23, which will be described later. It stops and springs between these members. The biasing force of the second biasing member 52 is set to be greater than the resistance force in the advancing/retreating direction due to friction or the like between the core breaker 30 and the lead core x.

The third urging member 53 is a compression coil spring whose front end is engaged with the clutch receiver 42 and whose rear end is engaged with the first tubular member 43, and urges the chuck portion 40 rearward. ing.

The first and second cylindrical members 43 and 44 are connected to the outer peripheral surface of the lead core x in a ring-like manner or in contact therewith over the entire circumference.

The first cylindrical member 43 is made of a hard synthetic resin material and has a substantially cylindrical shape. receiving the rear end of the
The inner peripheral surface of the first tubular member 43 is provided with a chamfered portion 43a, a tubular guide surface 43b, a locking projection 43c, and a pressure contact surface 43d in order from the rear end side (the right end side in the drawing). (See FIG. 2(a)).

The chamfered portion 43a is formed at the rear edge of the inner peripheral surface of the first tubular member 43 to facilitate the insertion of the second tubular member 44. As shown in FIG.

The cylindrical guide surface 43b is formed in a cylindrical shape with an inner diameter larger than the inner diameter of the plurality of locking projections 43c. This cylindrical guide surface 43b is in sliding contact with the front end side of the second cylindrical member 44 to be inserted, and maintains the concentricity of the second cylindrical member 44 at a high level.

A plurality of locking projections 43c (four in the illustrated example) are provided at regular intervals in the circumferential direction. Each locking projection 43c is formed in a rib shape that is continuous in the front-rear direction.
Specifically, as shown in FIG. 2(a), each locking protrusion 43c is formed in the shape of an inclined surface that slopes upward toward the top at its front end side and rear end side. is formed into a flat surface.

The press-contacted surface 43d is a cylindrical surface that is press-contacted by the fitting protrusion 44a2 of the second cylindrical member 44, and is formed to have an inner diameter slightly smaller than the outer diameter of the fitting protrusion 44a2.

The second tubular member 44 is made of a harder material (for example, a hard metal material) than the first tubular member 43, and is inserted into and fitted to the first tubular member 43 from the rear side. A fitting tubular portion 44a, a collar portion 44b that expands in diameter on the rear side of the fitting tubular portion 44a and contacts the rear end of the first tubular member 43, and a guide tubular portion that protrudes rearward from the flange portion 44b. 44c integrally (see FIGS. 1 and 3).

The cylindrical fitting portion 44a includes a front cylindrical surface portion 44a1, a jumping fitting projection 44a2 annularly projecting radially outward on the rear side of the front cylindrical surface portion 44a1, and a rear cylindrical surface portion rearward of the riding fitting projection 44a2. 44a3.

The front cylindrical surface portion 44a1 is formed in a cylindrical shape, and comes close to or comes into contact with the plurality of locking projections 43c during the assembly work of inserting the first cylindrical member 43 into the second cylindrical member 44 (Fig. 4(b)). )reference ).
A chamfered portion 44a4 whose diameter decreases forward is provided at the front edge of the outer peripheral surface of the front cylindrical surface portion 44a1 (see FIG. 3). A chamfered portion 44a5 whose diameter increases forward is provided at the front end edge of the inner peripheral surface of the front cylindrical surface portion 44a1.

The chamfered portion 44 a 4 on the outer peripheral side is for facilitating introduction of the second tubular member 44 into the first tubular member 43 .
The chamfered portion 44a5 on the inner peripheral side reduces friction, catching, etc., on the lead core x sliding backward when the lead core x is pushed backward while pushing the lead tank portion 60 forward. to prevent damage to the lead core x.
Although these chamfered portions 44a4 and 44a5 are C-chamfered in the example of FIG. 3, they may be R-chamfered or inclined surfaces of other shapes.

The overriding fitting projection 44a2 is an annular projection that protrudes radially outward. According to the illustrated example, the diameter-reduced inclined surface 44a21 directed forward and the cylindrical surface 44a22 connected to the rear side of the diameter-reduced inclined surface 44a21 are shown. Consists of
When the second tubular member 44 is inserted into the rear end opening of the first tubular member 43, the fitting projection 44a2 pushes the locking projection 43c inside the first tubular member 43 forward. The front and back positions are set so that it can be overcome.
The outer diameter of the fitting protrusion 44 a 2 is set slightly larger than the inner diameter of the pressure contact surface 43 d inside the first cylindrical member 43 .

The rear cylindrical surface portion 44a3 is a cylindrical surface that is longer in the front-rear direction than the locking projections 43c of the first cylindrical member 43, and comes close to or comes into contact with the tips of the plurality of locking projections 43c ( See FIG. 4(c)).

Further, the guide tube portion 44c is formed in a cylindrical shape extending rearward.
The guide tube portion 44c is inserted into the front end side of the lead tank portion 60, and comes into sliding contact with the inner peripheral surface of the lead tank portion 60 on the front end side when the lead tank portion 60 advances and retreats.

The lead tank part 60 has a substantially cylindrical shape with an open front end, and supplies the lead core x from the rear side to the lead lead feeding mechanism M1. The illustrated lead tank portion 60 includes a sliding cylinder portion 61 inserted into the rear end side of the holding cylinder 10 so as to be able to move forward and backward, and a cylindrical tank connected to the sliding cylinder portion 61 and extending rearward. It is composed of a body portion 62 .
It should be noted that the lead tank portion 60 can be configured by a single tubular member as another example other than the illustrated example.

Further, the motion direction conversion mechanism M2 is composed of the first cylindrical portion 11, the holder 20, the holder biasing member 23, and the like, and the force component in the radial direction applied to the holder 20 via the lead core x causes the lead core x to move. to move the holder 20 forward. It is possible to apply the mechanism disclosed in Patent Document 1 to this motion direction conversion mechanism M2.

Next, manufacturing features of the mechanical pencil unit 1 having the above configuration will be described with reference to FIGS. 4(a) to 4(c).
In the manufacturing method of the mechanical pencil unit 1, the second tubular member 44 is inserted into the first tubular member 43, and the plurality of locking projections 43c of the first tubular member 43 are engaged with the second tubular member. includes a step of getting over the fitting protrusion 44a2 of the cylindrical member 44 of .

Specifically, as illustrated in FIGS. 4A and 4B, when inserting the second tubular member 44 into the rear end opening of the first tubular member 43, the second tubular member 44 is first The front side cylindrical surface portion 44a1 of the tubular member 44 advances while being guided by the tubular guide surface 43b, and enters the plurality of locking projections 43c.
During this forward movement, as shown in FIG. 4(b), the reduced-diameter sloped surface 44a21 on the front side of the fitting projection 44a2 of the second tubular member 44 is aligned with the tubular guide surface 43b of the first tubular member 43. As shown in FIG. The center position of the second tubular member 44 with respect to the first tubular member 43 is corrected by pressing against and sliding against.

Further, when the second tubular member 44 is advanced with respect to the first tubular member 43, the overriding fitting projection 44a2 advances while being pressed against the locking projection 43c.
During this forward movement, the first tubular member 43 is made of a softer material than the second tubular member 44, and thus partially deforms the locking projection 43c. Therefore, deformation of the entire first cylindrical member 43 in the circumferential direction is suppressed.
Then, the climbing fitting projection 44 a 2 climbs forward over the locking projection 43 c and is pressed against the pressed surface 43 d of the first cylindrical member 43 . Therefore, the concentricity of the second tubular member 44 with respect to the first tubular member 43 is kept high.

Therefore, according to the mechanical pencil unit 1 configured as described above and the method for manufacturing the same, when fitting and connecting the thin first cylindrical member 43 and the second cylindrical member 44, the first cylindrical member 43 is It is possible to prevent damage due to being stretched in the circumferential direction, and obtain a highly concentric and highly accurate connection structure.

Then, the mechanical pencil unit 1 having the above configuration is incorporated into a multifunctional retractable writing instrument A, as illustrated in FIG.
In the multi-function retractable writing instrument A, by selectively advancing a plurality of pieces a2 and a3, the front end writing part of the refill connected to the advanced piece a2 (or a3) protrudes forward from the front end of the barrel a1. Let Said refill is, according to the illustrated example, a mechanical pencil unit 1 or a ballpoint pen refill 2 .
For example, a piece a2 having a clip a6 with an opening/closing function is operated to advance against the biasing force of a coil spring a4, and the front end writing portion of a mechanical pencil unit 1 (refill) connected to this piece a2 moves toward the shaft tube a1. When the piece a2 protrudes forward from the front end opening of the shaft tube a1, the piece a2 is locked by the locking portion a5 provided in the shaft tube a1, and this projecting state is maintained.
When the clip a6 is moved forward in this projected state, the lead x is drawn out from the front end of the mechanical pencil unit 1. As shown in FIG.
For this multifunctional retractable writing instrument A, for example, the basic structure shown in Japanese Patent Application Laid-Open No. 2014-198439 can be applied.

<Modification>
According to the above-described embodiment, as a particularly preferable example, the locking projection 43c is formed in the shape of a rib extending in the front-rear direction. As another example, it is possible to use a projection that is partially circular or elliptical in plan view.

Further, in the mechanical pencil unit 1, the characteristic connection structure of the present embodiment is applied to the connecting portion between the first tubular member 43 and the second tubular member 44 that support the rear side of the chuck portion 40. However, this connection structure can also be applied to a mechanical pencil unit other than the illustrated example as a connection structure for connecting two cylindrical members that are close to or in contact with the outer peripheral surface of the lead core x.

Further, according to the above-described embodiment, as a particularly preferable example, the connecting structure of the first tubular member 43 and the second tubular member 44 is applied to the mechanical pencil unit 1 having the motion direction changing mechanism M2. However, as another example, it is also possible to construct a mechanical pencil unit that does not include the motion direction changing mechanism M2.

Further, the mechanical pencil unit 1 having the above configuration is configured as a mechanical pencil refill for the multifunctional retractable writing instrument A, but as another example, the mechanical pencil unit 1 is provided in the barrel to configure a single-function mechanical pencil. It is also possible to

Moreover, the present invention is not limited to the embodiments described above, and can be modified as appropriate without changing the gist of the present invention.

1: Mechanical Pencil Unit 10: Holding Cylinder 20: Holder 40: Chuck Part 43: First Cylindrical Member 43a: Chamfered Part 43b: Cylindrical Guide Surface 43c: Locking Protrusion 43d: Pressure Contact Surface 44: Second Cylinder Shaped member 44a: Fitting cylindrical portion 44a1: Chamfered portion 44a2: Riding fitting projection 44a21: Diameter-reduced inclined surface 44a3: Rear cylindrical surface portion 60: Core tank portion x: Lead core M1: Lead core feeding mechanism M2: Movement direction change mechanism

Claims (6)

In a mechanical pencil unit that feeds out a lead lead by a predetermined operation,
Equipped with a first tubular member and a second tubular member connected back and forth in close proximity to or in contact with the outer peripheral surface of the lead core,
the first cylindrical member has a plurality of locking protrusions circumferentially spaced on its inner peripheral surface;
The second tubular member is formed of a material harder than the first tubular member, and is inserted into the first tubular member and has a fitting protrusion at a position where it has overcome the locking protrusion. has
The first tubular member is a member that supports the base end side of the chuck portion that clamps the lead core, and the second tubular member is connected to the rear side of the first tubular member. A mechanical pencil unit characterized by 2. The mechanical pencil unit according to claim 1, wherein said first tubular member is made of a synthetic resin material, and said second tubular member is made of a metal material. 3. The mechanical pencil unit according to claim 1, wherein said fitting protrusion is formed in an annular shape. A cylindrical guide surface having an inner diameter larger than the tip inner diameters of the plurality of locking protrusions is provided on the inner peripheral surface of the first cylindrical member closer to the second cylindrical member than the locking protrusions . The mechanical pencil unit according to any one of claims 1 to 3, characterized in that the mechanical pencil unit is A retractable writing instrument comprising the mechanical pencil unit according to any one of claims 1 to 4 . The method of manufacturing a mechanical pencil unit according to any one of claims 1 to 4 , wherein the second tubular member is inserted into the first tubular member to get over the locking protrusion. A method of manufacturing a mechanical pencil unit, comprising a step of getting over the fitting projection.

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