JP2014024281A - Mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that mechanical pencils according to conventional techniques, when supplying a lead to a chuck body or a relaying member or the like provided on a front end of a lead tank, may require time in inserting the lead into a lead insertion hole because precise circle-shape formation of the lead insertion hole inhibits a writing lead from moving along a circumferential shape inner wall of the lead insertion hole to fall into the center of the lead insertion hole, therefore delaying feeding of the lead.SOLUTION: A mechanical pencil has a lead feeding mechanism arranged in a shaft tube thereof. The lead feeding mechanism comprises: a lead housing part for housing a plurality of leads; and a lead insertion hole in succession to the front end of the lead housing part, into which one writing lead can be inserted, where the inner diameter shape of the lead insertion hole is formed polygonally.

Description

  The present invention relates to a mechanical pencil having a core insertion hole through which a single writing core can be inserted.

2. Description of the Related Art Conventionally, as a lead tank in a mechanical pencil, it has a lead storage part that stores a plurality of lead parts, and a lead insertion hole that allows a single writing lead to be inserted through the front end of the lead storage part. There is known a structure for supplying a lead from a part to a lead feeding mechanism.
One example is a core tank in which a core insertion hole continuous from the core storage portion is formed in a circular shape so that a single writing core can be inserted (Japanese Patent Laid-Open No. 2011-851 (Patent Document 1)).

  In the lead tank described in Patent Document 1, the lead insertion hole that is continuous from the lead storage portion is formed in a circular shape so that one writing lead can be inserted, so that two writing leads are provided in the lead insertion hole. It is possible to prevent the wicks from competing with each other and preventing the wick from coming out.

JP 2011-851 A

  However, in the prior art described in Patent Document 1, the core insertion hole is formed in a circular shape when the core is supplied to a chuck body or a relay member disposed at the front end of the core tank. Therefore, the writing core does not move along the circumferential inner wall of the core insertion hole and falls to the center of the core insertion hole, and there is a possibility that it takes time until the core is inserted into the core gripping portion of the chuck body. . As a result, the feeding of the lead may be delayed.

  The present invention is a mechanical pencil in which a lead feeding mechanism is disposed in a shaft cylinder, and the lead feeding mechanism is continuous with a lead storage portion for storing a plurality of leads and a front end of the lead storage portion. The gist of the present invention is to have a core insertion hole through which the writing core can be inserted, and the inner diameter of the core insertion hole is formed in a polygonal shape.

  The present invention is a mechanical pencil in which a lead feeding mechanism is disposed in a shaft cylinder, and the lead feeding mechanism is continuous with a lead storage portion for storing a plurality of leads and a front end of the lead storage portion. Since the inner diameter of the core insertion hole is formed in a polygonal shape, the writing core can be quickly inserted from the core storage portion to the core gripping portion of the chuck body. And a mechanical pencil with good lead feeding can be provided.

It is an external view of the whole product of 1st Example. It is an external view at the time of rotating 180 degree | times to the circumferential direction from the state of FIG. It is an external view at the time of rotating 90 degree | times to the circumferential direction from the state of FIG. It is a longitudinal cross-sectional view in the state of FIG. It is an enlarged view of the front member 4 periphery in FIG. It is an external appearance perspective view of the core tank 7 in a present Example. It is a longitudinal cross-sectional view of the core tank 7 in a present Example. It is the BB sectional view taken on the line in FIG. It is the sectional view on the AA line in FIG. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4 when the inner diameter shape of the core insertion hole 30 is a regular hexagon. 3 is a cross-sectional view showing a state of a spare core L ′ when a 0.3 mm core is present at the center of the core insertion hole 30. FIG. FIG. 3 is a cross-sectional view when two 0.3 mm spare cores L ′ are arranged in parallel with the core insertion hole 30. FIG. 6 is a cross-sectional view when a 0.5 mm core is inserted into the core insertion hole 30. It is a longitudinal cross-sectional view of the whole product in a 1st modification. It is CC sectional view taken on the line in FIG. It is a cross-sectional view of the core tank 7 including the core insertion hole 30 in the second modification.

  The operation will be described. The present invention is a mechanical pencil in which a lead feeding mechanism is disposed in a shaft cylinder, and the lead feeding mechanism is continuous with a lead storage portion for storing a plurality of leads and a front end of the lead storage portion. A core insertion hole that allows the writing core to be inserted is formed, and the inner diameter of the core insertion hole is formed in a polygonal shape. For this reason, when the first writing lead is drawn out, or when the second writing lead drawn out so as to follow the first writing lead passes through the lead insertion hole from the lead storing portion, it follows the inner wall of the lead insertion hole. Even when trying to move, the movement is controlled by contacting the vertex of the polygonal shape. As a result, useless movement while the writing core passes through the core insertion hole can be eliminated. In addition, by configuring the inner wall with the side facing the center of the core insertion hole, the writing core can easily fall to the center of the core insertion hole, and the core can be quickly supplied to the core gripping portion of the chuck body. A good mechanical pencil can be provided.

  A first embodiment of the present invention will be described with reference to FIGS. In addition, below, the front member 4 side mentioned later is called the front, and the press member 18 side is called back.

The shaft cylinder 1 includes a stainless steel pipe 2 at the front, a tip member 4 in which a core holding member 3 is press-fitted and fixed, and a shaft cylinder main body 5 arranged by screwing at the rear end of the tip member 4. A core feeding unit (core feeding mechanism) 6 is arranged inside the shaft tube 1. The shaft cylinder main body 5 is sandwiched between the tip member 4 and the core feeding unit 6, and as will be described later, by screwing the tip member 4 and the core feeding unit 6, the shaft cylinder body 5 is inserted. The main body 5 is fixed.
The lead feeding unit (lead feeding mechanism) 6 has a lead tank 7 for storing the lead, and a relay member 8 is fixed to the front end of the lead tank 7 by press fitting. A chuck body 9 for holding and releasing the writing core L is fixed in front of the intermediate member 8, and a chuck ring 10 for opening and closing the chuck body 9 is surrounded by the chuck body 9. Arranged in a state. The chuck body 9 grips and releases the writing core L by a core gripping portion 38 formed in front of the chuck body 9. Further, an intermediate screw member 11 is disposed so as to enclose the intermediate member 8, the chuck body 9, and the chuck ring 10. The positioning of the middle screw member 11 is performed by contacting the stepped portion 12 formed inside the front of the middle screw member 11 with the rear end surface of the chuck ring 10 and the large diameter portion formed behind the middle screw member 11. An elastic member (coil) stretched between the rear end of 13 and the front end of the step portion 14 formed in front of the core tank 7 and formed by a first reduced diameter portion 36 and a second reduced diameter portion 37 described later The spring 15 is used. The elastic member 15 biases the chuck body 9, the relay member 8 and the core tank 7 to the rear of the shaft cylinder 1 when the core feeding unit 6 is disposed in the shaft cylinder 1. Further, an eraser receiving member 16, an eraser 17 held by press fitting to the eraser receiving member 16, and a pressing member 18 are detachably attached to the rear end of the core tank 7.
Here, the fixing method of the shaft cylinder main body 5 by the tip member 4 and the core feeding unit 6 will be described in detail. A female screw portion 19 is formed on the rear inner surface of the tip member 4, while a male screw portion 20 is formed on the outer surface of the reduced diameter portion 14 of the middle screw member 11 in the core feeding unit 6. Yes. The shaft cylinder body 5 has a small diameter portion 21 on the front inner surface thereof, and a step portion 22 is formed at the rear end of the small diameter portion 21 by the small diameter portion 21. By positioning the stepped portion 22 of the shaft cylinder body 5 and the front end of the large diameter portion 13 of the intermediate screw member 11, the core feeding unit 6 is positioned within the shaft tube body 5, By screwing the male screw portion 20 of the intermediate screw member 11 and the female screw portion 19 of the tip member 4 projecting from the shaft tube main body 5 until the tip member 4 and the shaft tube main body 5 come into contact with each other, the shaft The cylinder body 5 is fixed.
Reference numeral 23 denotes a metal clip attached to the upper part of the shaft cylinder main body 5. The clip 23 is fitted in a recess 24 formed on the rear side of the shaft cylinder body 5.

A reduced diameter portion (gripping portion) 25 is formed in the front portion of the shaft cylinder main body 5, and a metal cylindrical gripping member 26 is attached to the reduced diameter portion (gripping portion) 25. . In this embodiment, the shaft body 5 is made of acrylonitrile styrene butadiene resin (ABS). However, the present invention is not limited to this, and the inner shaft body can be made of any material.
A circumferential protrusion 27 is formed in a front portion of the reduced diameter portion 25 of the shaft cylinder main body 5, and this circumferential protrusion 27 serves as a step-over step portion when the gripping member 26 is attached. . Further, a trapezoidal portion (trapezoidal portion 28) protruding in the forward direction of the shaft tube 1 is formed at the rear portion of the reduced diameter portion 25 of the shaft tube main body 5, and this shaft tube side trapezoidal portion 28. Is larger than the diameter-reduced portion 25.

Next, the lead tank 7 in the present embodiment will be described in detail (FIGS. 6 to 9).
A lead accommodating portion 29 having the largest inner diameter is formed behind the inner diameter portion of the lead tank 7 of the present embodiment, and a spare lead L ′ that is appropriately supplied as the writing lead L decreases is accommodated. The lead accommodating portion 29 has a gently tapered shape that decreases in diameter toward the front end, and has an inner diameter that allows about two to five spare cores L ′. The reason why the lead accommodating portion 29 is formed in a gentle taper shape is to improve the release of the core pin when the lead tank 7 is formed.
At the front end of the lead accommodating portion 29, a lead insertion hole 30 having an inner diameter through which only one writing lead can pass is formed in a regular heptagon. A gentle taper portion 31 is continuously formed between the core insertion hole 30 and the core storage portion 29, and the taper portion 31 allows the spare core L ′ to the core insertion hole 30 reduced in diameter. Allows for the rapid passage of Further, a press-fit portion 32 having a diameter larger than that of the core insertion hole 30 is formed at the front end of the core insertion hole 30 to facilitate the press-fitting of the intermediate member 8. In this embodiment, the intermediate member 8 is press-fitted and fixed to the press-fit portion 32, but it goes without saying that another member such as the chuck body 9 may be press-fitted.
In the present embodiment, the inner diameter shape of the core insertion hole 30 is a polygonal shape. As will be described later, by forming the inner diameter shape into a polygon, a vertex 33 that can control the movement of the writing core L and a side 34 that faces the center of the core insertion hole 30 can be formed in the core insertion hole. it can.

Next, the outer diameter shape of the core tank 7 will be described in detail (FIG. 6).
The outer diameter portion of the core tank 7 includes a maximum diameter portion 35, a first reduced diameter portion 36, and a second reduced diameter portion 37. The maximum diameter portion 35 is formed with a uniform thickness along the core storage portion 29 described above, and has a gentle taper shape like the core storage portion 29. At the front end of the maximum diameter portion 35, a first reduced diameter portion 36 is formed in a circular shape in cross section so as to match the reduced diameter from the inner core storage portion 29 to the core insertion hole 30. In this way, the outer diameter portion is also reduced in accordance with the reduced diameter of the inner diameter shape, and the thickness of the entire part is made substantially uniform, so that sink marks during molding can be prevented. Further, a second reduced diameter portion 37 is provided in front of the first reduced diameter portion 36, and a step portion 36 for urging the core tank 37 rearward by the resilient member 15 is formed.

As described above, in the lead tank 7 of the present embodiment, the inner diameter shape of the lead insertion hole 30 is formed in a regular heptagon (FIGS. 8 and 9). By forming the inner diameter shape into a regular heptagon, when the first writing core is fed out, the second writing core that is fed out to follow the first writing core passes through the core insertion hole 30 from the core storage portion 29. Even when trying to move along the inner wall of the core insertion hole 30 when passing, the movement is controlled by the writing core L coming into contact with the apex 33. As a result, useless movement of the writing core L can be eliminated. Furthermore, by configuring the inner wall with the side 34 facing the center of the core insertion hole 30, the writing core L that is in contact with the side 34 is rebounded toward the center and easily falls to the center of the core insertion hole 30. As described above, the writing core L can be quickly supplied to the core gripping portion 38 of the chuck body 9, and a mechanical pencil with good core feeding can be provided.
If the inner diameter is a perfect circle and the writing core L is likely to fall into the center of the core insertion hole 30 as in the prior art, a method of narrowing the clearance between the writing core L and the core insertion hole 30 can be considered. . However, when the clearance is narrowed, the passage from the core storage portion 29 to the core insertion hole 30 becomes worse, and parts such as the chuck body 9 and the intermediate member 8 are slightly shifted from the axis of the core insertion hole 30. If this is the case, the writing core L may be rubbed by the inner wall of the core insertion hole, and the writing core L may be difficult to pay out. That is, by making the inner diameter shape of the core insertion hole 30 into a regular heptagon as in this embodiment, the clearance between the writing core L and the core insertion hole 30 can be secured, and good core feeding can be realized.
In the present embodiment, the inner diameter shape of the core insertion hole 30 is a regular heptagon, but any polygon can be used as long as it is composed of a vertex 33 that can control the movement of the writing core and a side 34 that faces the center of the core insertion hole 30. Even if it is a shape, the same effect can be obtained, and a mechanical pencil with good lead-out can be provided. For example, as shown in FIG. 10, the inner diameter shape of the core insertion hole 30 may be a regular hexagon. In addition, even if the vertex 33 of the polygonal shape has an R at the time of processing or the like, there is no effect if the R is smaller than the core diameter to be used. Can be provided.

  In this embodiment, the lead tank 7 is made of polypropylene resin (PP), but the material for forming the lead tank 7 is not limited to polypropylene resin (PP). As a material used for forming the core tank 7, it is sufficient that the core insertion hole 30 can be formed in a polygonal shape. Specific examples of the material include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polypropylene resin (PP), polystyrene resin (PS), acrylonitrile styrene resin (AS), acrylonitrile butadiene styrene resin (ABS), Examples of the resin material include methacrylic resin (PMMA), polyacetal resin (POM), polyamide resin (PA), polycarbonate resin (PC), and polyethylene terephthalate resin (PET). Any material can be used as long as it can be formed into a polygonal shape.

Further, in this embodiment, the core insertion area is reduced by changing the inner diameter shape of the core insertion hole 30 from a perfect circle shape to a polygonal shape. The tank 7 can be used in common. The core insertion area referred to here is a cross-sectional area of the core insertion hole 30.
For example, with the configuration of the present embodiment, the core insertion hole 30 is formed in a regular heptagon inscribed in φ0.78, so that a writing core (0.3 mm core) with a display diameter of 0.3 according to JIS and a display according to JIS are displayed. A common use of the lead tank 7 is possible with a writing lead (0.5 mm lead) having a diameter of 0.5. By forming the polygonal shape as a polygon having an odd number of vertices, the opposite side of the vertex 33 becomes the side 34 in the cross section. As a result, the core insertion area can be effectively reduced. When a 0.3 mm lead is used, if the writing lead L is present at the center of the lead insertion hole 30 as shown in FIG. 11, there is no gap through which the spare lead L ′ can pass, and the spare lead L ′ Can prevent intrusion. A broken line portion in FIG. 11 is a virtual line representing the spare core L ′ of 0.3 mm. As shown in FIG. 12, even when the spare core L ′ is arranged in parallel and passes through the core insertion hole 30 when the first or second one is drawn out, the core insertion area is larger than the width in which the 0.3 mm core is arranged in parallel. Since they are formed narrowly, they do not pass through at the same time. A broken line portion in FIG. 12 is an imaginary line representing a 0.3 mm core. In addition, as shown in FIG. 13, even when a 0.5 mm core is used, a sufficient clearance can be formed between the writing core L and the core insertion hole 30 and the writing core can be passed quickly. Here, φ0 is used to secure the core insertion area of the core insertion hole so that two 0.3 mm cores do not enter, and to provide sufficient clearance between the writing core and the inner wall of the core insertion hole when using a 0.5 mm core. A polygonal shape inscribed in the range of .79 to φ0.75 is desirable. In the case of a polygon inscribed in a circle larger than φ0.79, the interval between the facing vertices is equal to or more than the outer diameter of two 0.3 mm cores. When the 0.3 mm cores are parallel and try to pass through the core insertion hole 30 at the same time, the end surface of the core is scraped or the outer diameter of the 0.3 mm core is reduced due to variations Then, there are two writing cores L in the core insertion hole 30, and the writing cores may be clogged or the writing cores may compete with each other, so that the writing cores may not come out. On the other hand, in the case of a polygon inscribed in a circle smaller than φ0.74, sufficient clearance cannot be taken between the 0.5 mm core and the core insertion hole, and competition is made between the writing core L and the inner wall of the core insertion hole 30. Therefore, there is a possibility that the lead feeding out may be delayed.
In addition to the common use of the 0.3 mm core and the 0.5 mm core, the inner diameter of the core insertion hole is changed to a polygonal shape so that the 0.5 mm core and the 0.7 mm core (display diameter 0 described in JIS) .7 writing cores) and 0.7 mm cores and 0.9 mm cores (writing cores with a display diameter of 0.9 as described in JIS) can be used in common for core tanks. As described above, by using a common core tank with different core diameters, it is possible to eliminate mistakes in assembling parts and further promote cost reduction.

Further, in the present embodiment, even if writing is performed in a state where the writing core L and the spare core L ′ overlap in the longitudinal direction within the core insertion hole 30 by making the core insertion hole 30 polygonal, Since the movement of the core L ′ is restricted by the polygonal vertex 33, it is possible to prevent wear due to rubbing between the end surfaces of the writing core L and the spare core L ′, and the core insertion hole 30 of the core waste generated by the wear can be prevented. The clogging can be eliminated, and the spare core L ′ can be stored in the initial state.
In addition to this, the polygonal-shaped part in the core tank during assembly makes it possible to fix the core tank to the assembly jig so that the core tank does not rotate. be able to.

In addition, in the present embodiment, the core tank 7 is formed with a polygonal shape by forming a core insertion hole 30 having an inner diameter through which only one writing core can pass, but the core insertion hole 30 is continuous with the core storage portion of the core tank 7. However, it is sufficient that the writing core L has a polygonal inner diameter that allows only one of the writing cores L to pass through until the core is supplied to the core gripping portion 38 of the chuck body 9. Not exclusively. That is, even if the core insertion hole 30 is formed in the inner diameter portion of the chuck body 9 press-fitted and fixed to the front end of the core tank 7, the same effect can be obtained (first modified example, FIGS. 14 to 15). As in the first embodiment, when the intermediate member 8 is interposed between the chuck body 9 and the core tank 7, the inner diameter that allows only one writing core L to pass through the inner diameter portion of the intermediate member 8. However, the polygonal core insertion hole 30 may be formed.
In this modification, the inner diameter shape from the rear end of the chuck body 9 to the core gripping portion 38 of the chuck body 9 is formed as a regular heptagon inscribed in φ0.78. Providing the core insertion hole 30 in the chuck body 9 makes it possible to eliminate local reduced diameter portions in the chuck body 9 and the core tank 7. Thereby, the wall thickness can be made substantially uniform in the longitudinal section, the diameter of the core insertion hole 30 due to sink marks during molding and the deformation of the polygonal shape can be prevented, and the core insertion hole 30 can be formed more reliably. The core can be quickly supplied to the core gripping portion 38 of the chuck body 9.
If the core insertion hole 30 is formed by locally reducing the inner diameter of the core tank 7 or the like, the inner diameter shape and the outer diameter shape of the core insertion hole 30 are made the same, and the wall thickness is made uniform across the cross section. Thus, sink marks at the time of molding can be prevented more reliably (second modified example, FIG. 16).

DESCRIPTION OF SYMBOLS 1 Shaft cylinder 2 Pipe 3 Core holding member 4 Tip member 5 Shaft cylinder main body 6 Center feeding unit (core feeding mechanism)
7 core tank 8 intermediate member 9 chuck body 10 chuck ring 11 middle screw member 12 step portion 13 large diameter portion 14 step portion 15 elastic member (coil spring)
DESCRIPTION OF SYMBOLS 16 Eraser receiving member 17 Eraser 18 Pressing member 19 Female screw part 20 Male screw part 21 Small diameter part 22 Step part 23 Clip 24 Recessed part 25 Reduced diameter part (gripping part)
26 Gripping member 27 Circumferential protrusion 28 Shaft side trapezoidal part 29 Core storage part 30 Core insertion hole 31 Taper part 32 Press-fit part 33 Vertex 34 Side 35 Maximum diameter part 36 First reduced diameter part 37 Second reduced diameter part 38 Core gripping part L Writing core L 'Spare core

Claims (4)

A mechanical pencil in which a lead feeding mechanism is arranged in a shaft cylinder, wherein the lead feeding mechanism has a lead storing part for storing a plurality of leads, and a single writing lead connected to the front end of the lead storing part. A mechanical pencil having a core insertion hole that can be inserted and having an inner diameter shape of the core insertion hole formed in a polygonal shape. The mechanical pencil according to claim 1, wherein the polygonal shape is a polygon having an odd number of vertices. The mechanical pencil according to claim 1 or 2, wherein the core insertion hole is formed in a core tank. The mechanical pencil according to claim 3, wherein the core insertion hole is formed in an inner diameter reduced portion of the core tank.

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