JP4601185B2 - Knock mechanical pencil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a knock type mechanical pencil that holds a lead by pressing the head of a chuck against a tightening ring and feeds a certain amount of lead by removing the tightening ring from the head after the chuck is advanced.
[0002]
[Prior art]
In the conventional knock type mechanical pencil, the fastening ring is manufactured by cutting.
[0003]
[Problems to be solved by the invention]
Therefore, the conventional knock type mechanical pencil has irregularities due to cutting on the surface of the tightening ring, and burrs are generated at the cut portion, which damages the chuck head.
[0004]
In order to solve this problem, the fastening ring has to be barrel-processed, resulting in a very high cost.
[0005]
An object of the present invention is to provide a knock mechanical pencil that solves the above-described problems.
[0006]
[Means for Solving the Problems]
The present invention divides a core holding part into a plurality of parts, forms a raised head on the outer surface of the core holding part and holds the core, and is fitted over the chuck head to open and close the chuck. This is a knock-type mechanical pencil that includes a tightening ring and a spring for urging the chuck rearward, and advances the core by advancing the chuck. Further, the fastening ring is formed by forging so as to have substantially the same shape in the front and rear , and the inner diameter of the central portion of the fastening ring is smaller than the inner diameters of both ends.
[0007]
【Example】
Hereinafter, the knock type mechanical pencil of the present invention will be described with reference to FIGS. 1, 2, 3, and 4. In addition, let the left side of FIG. 1 be the front, and let the right side be the back. The core 1 to be used will be described as a core 1 having a diameter in the range of 0.55 mm to 0.58 mm. First, three kerfs 2A are formed at equal intervals to a length of 7 mm from the front end of the brass chuck 2 to form a core holding portion 2B divided into three. Further, the width of the kerf 2A is formed from 0.1 mm to 0.15 mm. In order to hold the core 1 without biting out, the core holding part 2B is formed to have a longitudinal length of 2 mm to 2.5 mm and an inner diameter of the core holding part 2B of 0.54 mm. A raised head portion 2C is formed on the outer surface of the core holding portion 2B, and a tapered surface 2D having a diameter reduced toward the rear in the longitudinal direction is formed on the head portion 2C. The taper angle of the taper surface 2D is in the range of 2 to 6 degrees, and about 3 degrees is particularly preferable in order to securely hold the core 1. The elastic piece 2E divided into three parts located behind the head 2C is formed to have a thickness of 0.2 mm to 0.35 mm in order to repeatedly expand the chuck 2 and easily close the chuck 2.
[0008]
Furthermore, the inner hole 2F located behind the lead holding part 2B of the chuck 2 can reliably pass one lead 1 to be used in order to reliably guide the lead 1 into the lead holding part 2B. The book needs to be formed to a diameter that cannot pass, and is formed to a diameter of 1 mm.
[0009]
The head 2C and the elastic piece 2E of the chuck 2 formed as described above are expanded by inserting a conical pin from the front, and the outer diameter thereof is slightly smaller than the inner diameter of the chuck sliding portion inner hole 3A of the base 3 described later. To form large.
[0010]
The rear outer surface 2G of the chuck 2 is appropriately formed with a larger diameter than the elastic piece 2E, and the outer diameter of the rear outer surface 2G is formed with a larger diameter than the inner diameter 4A of the core tank 4 described later. A step portion 2H is formed on the outer surface of the rear portion, and a core tank fixing portion 2I having substantially the same shape as the inner diameter 4A of the core tank 4 is formed. The rear part of the core tank fixing part 2I is further formed with a small diameter of about 0.1 mm, and an outer casing 2J is formed on the outer surface thereof. The outer casing 2J has a front surface formed vertically and a rear surface tapered so that the core tank 4 can be firmly press-fitted and fixed.
[0011]
The fastening ring 5 fitted on the head 2C of the chuck 2 is made of brass, and is formed by forging into a cylindrical shape having the same shape in the front and rear, and the inner diameter of the central portion is formed to be smaller than the inner diameters of both ends by about 0.04 mm. Moreover, the minimum inner diameter of the tightening ring 5 is formed to be slightly smaller than the outer diameter of the head 2C when the chuck 2 does not hold the core 1 and is closed.
[0012]
Since the tightening ring 5 is formed by forging, burrs are not generated on the end surface, and the surface is also formed smoothly, so that the taper surface 2D of the chuck 2 may be damaged even when pressed against the taper surface 2D of the chuck 2. There is no.
[0013]
Further, a disc-shaped washer 6 is fitted on the head 2 </ b> C of the chuck 2 so as to be located behind the fastening ring 5. The washer 6 is made of brass and has a recess 6A formed on the rear end surface for centering a spring 7 described later. The diameter of the recess 6A is slightly larger than the outer diameter of the spring 7.
[0014]
The core tank 4 is formed of a synthetic resin pipe, and its inner diameter 4A is set to a dimension in which three cores 1 to be accommodated are arranged side by side with a margin so that the core 1 can be positioned at the center of the core tank 4. Constitute. Further, the thickness of the lead tank 4 is set to 0.6 mm to 0.8 mm in order to prevent the lead tank 4 from bending and to make the outer diameter as thin as possible. The lead tank 4 is press-fitted and fixed to the outer flange 2J of the chuck 2, but the front end of the lead tank 4 is brought into contact with a step portion 2H formed on the rear outer surface of the chuck 2.
[0015]
Further, a spring 7 is stretched between the washer 6 and the core tank 4, and the front end of the spring 7 is centered by a recess 6 </ b> A of the washer 6. The mounting load of the spring 7 is set between 300 g and 600 g so that the core 1 can be reliably held and knocking can be easily performed. Furthermore, the effective diameter of the spring 7 is formed smaller than the outer diameter of the core tank 4 in order to ensure the operation.
[0016]
A front inner hole 8 </ b> A is formed in the shaft cylinder 8, and the front inner hole 8 </ b> A is formed to be thicker than the outer diameter of the core tank 4. Further, a rear inner hole 8B having a diameter larger than that of the front inner hole 8A is formed in the rear portion of the shaft cylinder 8, and a key groove 8C extending forward from the rear end is formed in the rear inner hole 8B. In addition, the rear end of the keyway 8C extends to one side to form a tapered guide for inserting a key 9A of the crown 9 described later. Further, a thin diameter portion 8D is formed on the outer surface of the front portion of the shaft tube 8, and a non-slip grip 10 made of thermoplastic elastomer or silicon rubber is attached to the small diameter portion 8D.
[0017]
The core tank 4 connected to the chuck 2 as described above is inserted into the front inner hole 8A of the shaft tube 8, and the base 3 is screwed into the front portion of the shaft tube 8. The grip 10 is sandwiched between the rear end of the base 3 and the outer stage 8E of the shaft tube 8, and the washer 6 is sandwiched between the inner stage 3B of the base 3 and the front end of the shaft cylinder 8. The fastening ring 5 is built in the base 3 so as to be slidable between the locking step 3C of the base 3 and the washer 6.
[0018]
A stainless steel guide pipe 11 is press-fitted and fixed to the front end of the base 3, and the guide pipe 11 protrudes appropriately from the front end of the base 3. A core holder 12 is built in the base 3. The lead holder 12 sets the force for holding the lead 1 to 3 g to 100 g, preferably 5 g to 20 g in order to reliably feed the lead 1. The rubber hardness of the lead holder 12 is set in the range of 60 to 90 degrees in order to maintain the lead holding force for a long period.
[0019]
The head crown 9 is integrally formed with the clip 13 on the upper side, and a small diameter portion 9B is formed at the front portion. A projection 9C is formed on the outer peripheral surface of the small-diameter portion 9B so as to be positioned directly below the clip 13, and a key 9A extending in the longitudinal direction is formed on the outer peripheral surface opposite to the projection 9C. Further, as shown in FIG. 2, opening windows 9D extending in the longitudinal direction are formed on both sides of the small diameter portion 9B so as to oppose each other, and the key 9A can be appropriately elastically deformed.
[0020]
A narrow diameter portion 9B is inserted into the head crown 9 from the rear end of the shaft tube 8, and the key 9A of the head crown 9 is fitted into the key groove 8C of the shaft tube 8. Then, the projection 9C of the crown 9 is inevitably positioned on the extension line of the locking window 8F of the shaft cylinder 8, and when the small diameter portion 9B of the crown 9 is further inserted, the projection 9C of the crown 9 is The head cap 9 is fixed to the shaft tube 8 without being aligned with the locking window 8F.
[0021]
A front inner hole 14A of an eraser support 14 inserted from the rear end of the shaft cylinder 8 is fitted to the rear part of the core tank 4, and is formed in the front inner hole 14A of the eraser support 14 as shown in FIG. The protrusion 14B is pressed against the rear outer surface of the lead tank 4. An eraser 15 is attached to the rear inner hole 14 </ b> C of the eraser support 14. Further, a synthetic resin knob 16 for covering the eraser 15 is fitted to the rear outer side of the eraser support 14, and a protrusion 16A formed on the front inner side of the knob 16 as shown in FIG. The knob 16 is attached by dropping into a concave groove 14D formed outside the rear portion of the support 14. An opening hole 16B is formed in the top of the knob 16 to prevent suffocation even if an infant swallows it by mistake. Note that the knob 16 and the eraser 15 are configured to protrude appropriately from the rear end of the crown 9.
[0022]
In the knock type mechanical pencil configured as described above, when the knob 16 is pressed, the chuck 2 moves forward and the lead 1 is fed out by a certain amount. When the fastening ring 5 comes into contact with the locking step 3 </ b> C of the base 3, the fastening ring 5 comes off from the head 2 </ b> C of the chuck 2 and the chuck 2 is expanded. The expanded chuck 2 comes into contact with the chuck sliding portion inner hole 3A of the base 3 and the expansion of the chuck 2 is restricted. At this time, the reason for bringing the chuck 2 into contact with the chuck sliding portion inner hole 3A of the base 3 is to center the chuck 2 so as to center the core holding portion 2B. When the chuck 2 is regulated by the chuck sliding portion inner hole 3A, the width of the kerf 2A of the chuck 2 is configured to be smaller than the outer diameter of the core 1 to prevent the core 1 from entering the kerf 2A. To do.
[0023]
FIG. 5 shows a second embodiment of the present invention, and the same members as those in FIG. A synthetic resin core holder 112 is press-fitted and fixed to the rear part of the stainless steel guide pipe 111, and the total weight is set to about 0.05 g. Further, an inner elastic piece 112A divided into a plurality of parts is formed at the rear part of the core holder 112, and the core 1 is held by the inner elastic piece 112A with a force of 3 g to 50 g. The guide pipe 111 and the core holder 112 are incorporated in the base 103 so as to be slidable in the longitudinal direction, and the outer elastic piece 112B of the core holder 112 is brought into frictional contact with the inner surface 103D of the base 103 with a force of 5 g to 200 g. Preferably, the force that holds the core 1 by the inner elastic piece 112A is 5 to 18 g, and the force that the outer elastic piece 112B frictionally contacts with the inner surface 103D of the base 103 is about 20 to 80 g. This is because the guide pipe 111 and the core holder 112 are prevented from being detached from the base 103 together with the core 1 held by the chuck 2 when the base 103 is removed. Further, the guide pipe 111 and the core holder 112 are configured not to be detached from the base 103 even if the base 103 is shaken. Further, the length from the front end of the chuck 1 to the front end of the base 103 is configured to be equal to or longer than the length from the front end of the guide pipe 111 to the rear end of the core holder 112, and the guide pipe 111 is completely immersed in the base 103. A configuration that can be used.
[0024]
The present invention is not limited to the above embodiment, and parts such as a chuck or a core tank may be integrated by press-fitting or fitting two or more parts. May be configured by forming ribs extending in the longitudinal direction at equal intervals in the circumferential direction.
[0025]
【The invention's effect】
In the knock type mechanical pencil of the present invention described above, the fastening ring is formed by forging, so that no burrs are generated and it can be manufactured at low cost. Further, since the tightening ring can be formed in substantially the same shape in the front and rear directions, the tightening ring can be assembled to the chuck head without confirming the direction of the tightening ring, and the productivity can be improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a first embodiment of a knock mechanical pencil of the present invention.
FIG. 2 is an enlarged cross-sectional view taken along line AA in FIG.
FIG. 3 is an enlarged cross-sectional view taken along line BB in FIG.
4 is an enlarged cross-sectional view taken along line CC in FIG. 1. FIG.
FIG. 5 is a sectional view showing a second embodiment of the knock mechanical pencil of the present invention.
[Explanation of symbols]
1 Core 2 Chuck 2B Chuck 2 Core Holder 2C Chuck 2 Head 5 Clamping Ring 7 Spring

Claims (1)

A chuck for holding the core by dividing the core holding part into a plurality of parts, forming a raised head on the outer surface of the core holding part, and a tightening ring fitted on the head of the chuck to open and close the chuck In the knock type mechanical pencil, which consists of a spring for urging the chuck backward, and the core is extended by advancing the chuck, the fastening ring is formed in a substantially the same shape in the front and rear by forging , and the inner diameter of the central part is the inner diameter of both ends. Knock-type mechanical pencil, characterized by a smaller diameter .

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