JP2020116837A - Mechanical pencil unit, retractable writing instrument, and method of manufacturing mechanical pencil unit - Google Patents

Abstract

To easily install a core breaker on a front end side in a holding cylinder.SOLUTION: A mechanical pencil unit includes: a lead core feeding mechanism M1 configured to feed a lead core x through a core breaker 30; and a holding cylinder 10 including the lead core feeding mechanism M1. The holding cylinder 10 includes: a first cylinder portion 11; and a second cylinder portion 12 connected to a rear side of the first cylinder portion 11 and protruding forward by inserting the core breaker 30 into a front end opening. The core breaker 30 is formed so that it can be inserted into the front end opening of the second cylinder portion 12 from a front side thereof.SELECTED DRAWING: Figure 2

Description

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

Conventionally, in connection with this type of invention, for example, in Patent Document 1, a holding cylinder and a front opening of the holding cylinder are inserted to project forward from the front end of the holding cylinder and to be able to move forward and backward with respect to the holding cylinder. A supported holder, a lead core feeding mechanism that inserts a lead core into a core breaker and feeds it toward the holder, and a radial force applied from the lead core to the holder causes the holder to move forward relative to the holding cylinder and the lead core. There is described a mechanical pencil unit including a movement direction changing mechanism for tilting the holder and a holder biasing member for biasing the holder rearward with respect to the holding cylinder. If the mechanical pencil unit is housed in the barrel, the retractable writing instrument can be easily constructed.
According to this retractable writing instrument, the mechanical pencil unit is moved forward by a predetermined operation, and when the holder at the front end of the mechanical pencil unit is projected from the opening at the front end of the barrel, the pencil core is projected radially from the holder. When the force is applied, the holder moves forward relative to the holding cylinder and the lead core, so that the holder can cover and protect the lead core.
Further, when the radial force is removed, the retracting holder can be brought into contact with the front end portion of the elastic core breaker to mitigate the contact noise.

JP, 2017-159580, A

However, according to the above-mentioned conventional technique, it is necessary to insert the core breaker from the rear side of the second cylinder part having a deep bottom and push the core breaker to the bottom part with a rod-shaped jig or the like, which reduces the number of working steps. Improvement was required.

In view of such a problem, the present invention has the following configurations.
A lead core feeding mechanism adapted to feed a lead core into a lead breaker and a holding cylinder having the lead core feeding mechanism therein, the holding barrel including a first tubular portion and the first tubular portion. A second cylinder part that is connected to the rear side of the cylinder part and that protrudes forward by inserting the core breaker through the front end opening is integrally provided, and the core breaker includes a second cylinder part of the second cylinder part. A mechanical pencil unit that is formed so that it can be inserted into the front end opening from the front side thereof.

Since the present invention is configured as described above, the core breaker can be easily mounted on the front end side in the holding cylinder.

It is a longitudinal cross-sectional view showing an example of a mechanical pencil unit according to the present invention. It is a longitudinal section showing a situation before and after inserting a core breaker in a 2nd cylinder part in order to (a) and (b). It is an internal structure figure showing an example of a writing instrument provided with the same mechanical pencil unit. It is a longitudinal cross-sectional view showing the action of the movement direction conversion mechanism, (a) shows a normal writing state, (b) shows a state in which the holder is advanced. In addition, hatching indicates a portion that has moved from the previous state.

The following features are disclosed in the present embodiment.
A first feature is a mechanical pencil unit, which includes a lead core feeding mechanism configured to feed a lead core through a lead breaker and a holding cylinder having the lead core feeding mechanism therein. Is integrally provided with a first tubular portion and a second tubular portion that is connected to the rear side of the first tubular portion and that protrudes forward by inserting the core breaker into the front end opening. The core breaker is formed so that it can be inserted into the front end opening of the second tubular portion from the front side thereof (see FIGS. 1, 2, and 4).

As a second feature, the core breaker has an outer diameter of a rear end edge thereof set to be smaller than an inner diameter of a front end opening edge of the second tubular portion (see FIG. 2 ).

As a third feature, the rear end side of the core breaker is gradually reduced in diameter toward the rear (see FIG. 2).

As a fourth feature, the front end side of the core breaker has a diameter increased on the front side of the second tubular portion (see FIG. 2 ).

A fifth feature is that a gap is provided between the outer peripheral surface of the core breaker on the front side and the inner peripheral surface of the second tubular portion such that the front side is larger than the rear side (see FIG. 2 ).

A sixth feature is that the holder is inserted into the front end opening of the first tubular portion and protrudes forward, and the holder is attached to the first tubular portion by a radial force component applied to the holder from the lead core. And a holder biasing member for biasing the holder backward, and the rear end of the holder is elastically received by the core breaker (see FIG. 4). ).

A seventh feature is that the retractable writing instrument is configured by including the mechanical pencil unit (see FIG. 3).

An eighth feature is a method of manufacturing the mechanical pencil unit, which includes a step of inserting the lead breaker into the front end opening of the second tubular portion from the front side thereof (see FIG. 2 ).

<Specific Embodiment>
Next, specific embodiments having the above characteristics will be described in detail with reference to the drawings. In the present specification, the axial direction means the direction in which the center line of the holding cylinder 10 extends. The term "front" means one side of the axial direction in which the lead core is fed. In addition, “rear” means a side opposite to the one side.

The mechanical pencil unit 1 shown in FIG. The holder 20 protruding forward, the movement direction conversion mechanism M2 for advancing and inclining the holder 20 relative to the holding cylinder 10 and the lead core x by the radial force component applied to the holder 20 from the lead core x, and the holding cylinder 10. And a lead tank portion 60 connected to the rear end side.

The holding tube 10 is connected to the first tube portion 11 that projects forward by inserting the holder 20 into the front end opening portion, and the core breaker 30 that is concentrically connected to the rear end side of the first tube portion 11. Is integrally provided with a second tubular portion 12 protruding forward from the front end opening and a third tubular portion 13 concentrically connected to the rear end side of the second tubular portion 12. ..
The second tubular portion 12 and the third tubular portion 13 can also be configured as an integral member.

The second tubular portion 12 is formed of a hard material such as metal into a tubular shape extending in the front-rear direction.
On the front end side of the outer peripheral surface of the second tubular portion 12, the joining surface 12a that is joined to the inner circumferential surface of the first tubular portion 11 in an overlapping manner and the diameter of the rear side of the joining surface 12a is increased. The formed step portion 12b is formed (see FIG. 2).

The joint surface 12a is integrated with the inner peripheral surface of the first tubular portion 11 by press fitting or screw connection.
The step portion 12b contacts the rear end portion of the first tubular portion 11 and positions the second tubular portion 12 in the front-rear direction with respect to the first tubular portion 11.

Further, on the front end side of the inner peripheral surface of the second tubular portion 12, as shown in FIG. 2, an annular locking convex portion 12c fitted in a concave-convex shape on the core breaker 30 is inserted from the front side. A guide surface portion 12d that elastically contracts the core breaker 30 and a fitted surface 12e that is fitted to the outer peripheral surface of the core breaker 30 on the rear end side are formed behind the locking projection 12c.

The locking protrusion 12c is an annular protrusion that protrudes radially inward, and is loosely fitted into the recess 32 of the core breaker 30 as illustrated in FIG. 2B.

The guide surface portion 12d is an annular inclined surface that gradually reduces its diameter toward the rear, and its rear end side is connected to the locking convex portion 12c inner diameter surface.
The guide surface portion 12d secures a gap s (see FIG. 2B) with the bottom surface of the recess 32 of the core breaker 30.

The fitted surface 12e is a cylindrical inner surface whose diameter is stepwise expanded with respect to the inner diameter surface of the locking projection 12c. The fitted surface 12e is set to have an inner diameter smaller than an outer diameter of the press contact portion 31 so as to press contact with a press contact portion 31 of the core breaker 30 described later.

The core breaker 30 is formed of an elastic material such as an elastomer resin or synthetic rubber into a substantially cylindrical shape, and is inserted into the front end opening of the second tubular portion 12 from the front side. See FIG. 2).
On the outer peripheral surface of the core breaker 30, an annular press-contact portion 31 press-contacted to the fitted surface 12e of the second tubular portion 12, and a locking projection of the second tubular portion 12 on the front side of the press-contact portion 31. An annular recess 32 that is loosely fitted to the portion 12c and an annular expanded portion 33 that has an enlarged diameter on the front side of the recess 32 and the front end of the second tubular portion 12 are provided.

A chamfered portion 37 that facilitates insertion of the second tubular portion 12 into the guide surface portion 12d is provided at the rear end edge of the press contact portion 31.
The chamfered portion 37 is formed in an annular shape that is smaller than the inner diameter of the front end opening edge of the second tubular portion 12 (specifically, the front end edge of the guide surface portion 12d) and gradually reduces in diameter rearward.
Although the chamfered portion 37 is formed in a C chamfer shape according to the illustrated example, it may be formed in an R chamfered shape as another example.

The recess 32 is formed in a cylindrical shape that is recessed radially inward with respect to the front and rear portions thereof.
The outer diameter of the bottom surface of the recess 32 is set to be smaller than the inner diameter of the locking projection 12c of the second tubular portion 12.

On the rear side of the enlarged diameter portion 33, an annular inclined surface 33a is formed which gradually reduces its diameter toward the rear. The inclined surface 33a is located away from the guide surface portion 12d, as shown in FIG. 2(b).
Further, the front end side of the expanded diameter portion 33 elastically receives the receiving portion 22 of the holder 20 from the rear side thereof (see FIG. 4).

The gap s (see FIG. 2B) in the second tubular portion 12 is defined by the outer peripheral surface of the lead breaker 30 on the front side (specifically, the front side of the bottom surface of the recess 32) and the inner peripheral surface of the second tubular portion 12. It is located between the surface (specifically, the guide surface portion 12d) and gradually increases toward the front.

Then, on the inner peripheral surface of the core breaker 30, an annular lead core introducing surface 34 whose diameter is gradually reduced toward the front on the rear side, and an outer peripheral surface of the lead core x on the front side of the lead core introducing surface 34. On the other hand, an annular gentle pressure contact portion 35 that is elastically and gently pressure-contacted, and an annular diameter-increasing inner surface portion 36 whose diameter is enlarged on the front side of the gentle pressure contact portion 35 are provided.

Further, as shown in FIG. 1, the lead core feeding mechanism M1 includes the core breaker 30 held in the second cylindrical portion 12, a chuck portion 40 that moves back and forth with respect to the core breaker 30, and a chuck. A clutch ring 41 that fits in an annular shape from the rear side to the portion 40, a substantially cylindrical clutch receiver 42 that receives the clutch ring 41 from the rear side, a support member 43 that supports the rear end side of the chuck portion 40, and a support member A guide cylinder portion 44, which is connected to the rear end side of the member 43 and guides the advance/retreat of the lead tank portion 60, and first to third biasing members 51 to 53.
The lead core feeding mechanism M1 feeds the lead core x sandwiched by the chuck portion 40 by the forward/backward movement transmitted from the lead tank portion 60. The lead core feeding mechanism M1 also retracts the lead core x together with the lead core x when a backward biasing force stronger than a preset writing pressure is applied to the lead core x sandwiched between the chuck portions 40. ..

Further, the movement direction conversion mechanism M2 is configured by the first tubular portion 11, the holder 20 that is included in the first tubular portion 11 and protrudes forward, the holder biasing member 23 that biases the holder 20 backward, and the like. , The holder 20 is moved forward relative to the lead core x and the holding cylinder 10 by the radial force component applied to the holder 20 via the lead core x.

The holder 20 is integrally configured of a holder main body portion 21 having a cam slope 21a and a receiving portion 22 connected to the rear side of the holder main body portion 21, and is supported so as to be movable back and forth with respect to the holding cylinder 10. The holder 20 is slightly inclined when it is advanced by the radial force component applied to the lead core x (see FIG. 4). In addition, the holder main body 21 and the receiving portion 22 may be an integral member.

The basic structure of the lead core feeding mechanism M1 and the movement direction converting mechanism M2 may be the one of Patent Document 1.

Further, the lead tank portion 60 is configured in a substantially cylindrical shape with an open front end portion, and supplies the lead core x from the rear side to the lead core feeding mechanism M1. The lead tank part 60 includes a slide cylinder part 61 engaged with the rear end side of the holding cylinder 10 so as to be able to move forward and backward, and a cylindrical tank main body part 62 connected to the slide cylinder part 61 and extended rearward. Composed of. The slide cylinder portion 61 and the tank main body portion 62 can be formed as an integral member.

Next, the characteristics of the mechanical pencil unit 1 having the above-described structure in terms of the manufacturing method will be described.
The method for manufacturing the mechanical pencil unit 1 includes a step of inserting the lead breaker 30 into the front end opening of the second tubular portion 12 from the front side thereof, as shown in FIG.

More specifically, first, the core breaker 30 is arranged concentrically on the front side of the second tubular portion 12.
Then, the lead breaker 30 is moved rearward, and the chamfered portion 37 of the lead breaker 30 is brought into contact with the guide surface portion 12d of the second tubular portion 12.
Further, when the movement of the core breaker 30 is continued rearward, the pressure contact portion 31 of the core breaker 30 is pressed against the locking projection 12c and elastically contracts, overcoming the locking projection 12c and moving backward. It moves and comes into pressure contact with the fitted surface 12e. Then, the concave portion 32 and the locking convex portion 12c are loosely fitted.

Therefore, according to the above manufacturing method, the core breaker 30 can be easily attached to the core breaker 30 from the front side and locked so as not to move in the front-rear direction.

In addition, in the example shown in FIG. 2, the core breaker 30 is attached to the single second tubular portion 12 from the front side thereof, but as another example, another configuration (the third tubular portion 13, It is also possible to mount the core breaker 30 from the front side of the second tubular portion 12 to which the lead core feeding mechanism M1 and the core tank portion 60 etc. are mounted.

Then, the mechanical pencil unit 1 having the above configuration is incorporated in the multifunctional retractable writing instrument A as illustrated in FIG.
The multifunctional retractable writing instrument A projects the front end writing portion of the refill connected to the advanced piece a2 (or a3) forward from the front end of the barrel a1 by the operation of selectively advancing the plurality of pieces a2, a3. Let According to the illustrated example, the refill is the mechanical pencil unit 1 or the ballpoint refill 9.
For example, a piece a2 having a clip a6 with an opening/closing function is moved forward against the urging force of the coil spring a4, and the front end writing portion of the mechanical pencil unit 1 (refill) connected to the piece a2 has a barrel a1. When projecting forward from the front end opening, the piece a2 is locked by the locking part a5 provided in the shaft cylinder a1, and this protruding state is maintained.
When the clip a6 is advanced in this protruding state, the lead core x is extended from the front end of the mechanical pencil unit 1.
The basic structure shown in, for example, JP-A-2014-198439 can be applied to the multifunctional retractable writing instrument A.

According to the multifunctional retractable writing instrument A having the above-described configuration, as shown in FIGS. 4A and 4B, the lead core x is strongly pressed against the writing surface p (for example, the paper surface), and the lead core x is then pressed. When an excessive radial force is applied to the holder 20, the cam sloped surface 21a slides on the front end opening of the holding cylinder 10 so that the holder 20 moves forward relative to the lead core x and the holding cylinder 10.
Then, when the radial force is removed, the holder 20 is retracted by the urging force of the holder urging member 23, the rear end of the receiving portion 22 contacts the core breaker 30, and the core breaker 30 is elastic. Then, it is deformed by compression and returns to the state shown in FIG.
At the time of the retreat, the enlarged diameter portion 33 on the front end side of the core breaker 30 flexibly elastically deforms so as to enter the gap s with the guide surface portion 12d.
Therefore, it is possible to effectively reduce the impact at the time of the contact, prevent the impact noise from being generated, and prevent the core breaker 30 from being displaced or disengaged due to the impact.

Further, even when the lead core x bends as the holder 20 moves forward and tilts (see FIG. 4B), the lead breaker can be elastically deformed so as to follow the bending of the lead core x. Therefore, breakage of the lead core x due to the bending can be prevented.

According to the above-described embodiment, the movement direction conversion mechanism M2 is provided as a particularly preferable mode, but as another example, the above-described core breaker 30 and the like are provided for the mechanical pencil unit that does not include the movement direction conversion mechanism M2. It is also possible to apply the structure of.

Further, the present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention.

1: Mechanical pencil unit 10: Holding cylinder 11: First cylinder part 12: Second cylinder part 13: Third cylinder part 20: Holder 30: Core breaker 31: Press contact part 32: Recessed part 33: Expanded part 60 : Core tank part s: Gap x: Lead core A: Multi-function retractable writing instrument M1: Lead core feeding mechanism M2: Movement direction conversion mechanism

Claims (8)

A lead core feeding mechanism adapted to feed a lead core through a core breaker, and a holding cylinder having the lead core feeding mechanism therein,
The holding cylinder integrally includes a first cylinder part and a second cylinder part connected to the rear side of the first cylinder part and protruding forward by inserting the core breaker into the front end opening. To prepare for
The mechanical pencil unit, wherein the lead breaker is formed so as to be insertable into the front end opening of the second tubular portion from the front side thereof. The mechanical pencil unit according to claim 1, wherein the lead breaker has an outer diameter of a rear end edge thereof set to be smaller than an inner diameter of a front end opening edge of the second tubular portion. The mechanical pencil unit according to claim 2, wherein the rear end side of the core breaker is gradually reduced in diameter toward the rear. The mechanical pencil unit according to any one of claims 1 to 3, wherein a front end side of the core breaker has a diameter that is larger than a front side of the second tubular portion. 5. A gap having a front side larger than a rear side is provided between the front outer peripheral surface of the core breaker and the inner peripheral surface of the second tubular portion. Mechanical pencil unit. A holder that is inserted into the front end opening of the first tubular portion and protrudes forward, and a forward force that tilts the holder relative to the first tubular portion due to a radial force component applied to the holder from the lead core. 6. A movement direction changing mechanism for causing the holder and a holder urging member for urging the holder backward, wherein the rear end of the holder is elastically received by the core breaker. The mechanical pencil unit according to claim 1. A retractable writing instrument comprising the mechanical pencil unit according to claim 1. 7. The method of manufacturing a mechanical pencil unit according to claim 1, further comprising a step of inserting the lead breaker into a front end opening of the second cylindrical portion from a front side thereof.

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