JP4302831B2 - Knock mechanical pencil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a knock type mechanical pencil that feeds a lead by advancing a chuck.
[0002]
[Prior art]
In conventional knock type mechanical pencils, the fastener is inserted in the inner hole of the base so as to be slidable in the longitudinal direction, or the rear part of the fastener is inserted in the front inner hole of the shaft cylinder so as to be slidable in the longitudinal direction. Was configured.
[0003]
[Problems to be solved by the invention]
Therefore, when a fastener is inserted into the inner hole of the base, the chuck with the fastener fitted laterally swings in the shaft cylinder, and the shaft center of the chuck and the core tank is displaced when the chuck and the core tank are press-fitted and connected. There was a risk that the chuck would be bent and attached.
[0004]
In addition, when the rear part of the fastener is inserted into the front inner hole of the shaft tube, the fastener swings in the inner hole of the base, and the core held by the chuck cannot pass through the core holder of the base. The problem that the lead cannot follow was caused.
[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 relates to a knock type mechanical pencil that feeds a lead by advancing a chuck, wherein a protrusion is formed at the rear part of the chuck and a front inner hole is formed at the front part of the lead tank. A guide hole formed at a diameter larger than the outer diameter of the protrusion of the chuck is formed at the front of the chuck, and the protrusion of the chuck is determined by the difference between the radius of the guide hole of the core tank and the radius of the front inner hole of the core tank. The difference between the radius of the strip and the radius of the outer periphery of the rear end of the chuck is large, and the chuck is inserted from the front of the shaft cylinder, and the core tank is inserted from the rear of the shaft cylinder. The projecting ridge portion is press-fitted and connected to the front inner hole of the core tank, and the outer flange of the fastener is loosely slidably fitted in the longitudinal direction between the inner stage of the base and the shaft tube, and further, Insert the front part into the inner hole of the base slidably in the longitudinal direction, The rear portion of the ingredients in the front bore of the barrel is obtained by slidably inserted in the longitudinal direction.
[0007]
【Example】
Hereinafter, the knock type mechanical pencil of the present invention will be described with reference to FIG. The left side of the drawing is the front and the right side is the rear. A synthetic resin base 2 is detachably screwed into the front portion of the shaft tube 1, and a rubber core holder 4 for holding the core 3 with an appropriate force is built in the base 2. Further, a stainless steel guide pipe 5 is fixed to the tip of the base 2.
[0008]
Between the inner stage 2A of the base 2 and the front end of the shaft tube 1, an outer flange 6A of the fastener 6 is loosely fitted so as to be slidable in the longitudinal direction as appropriate, and the front portion 6B of the fastener 6 is an inner hole 2B of the base 2. Is slidably inserted in the longitudinal direction. The rear portion 6C of the fastener 6 is inserted into the front inner hole 1A of the shaft tube 1 so as to be slidable in the longitudinal direction.
[0009]
Therefore, since the rear portion 6C of the fastener 6 is guided by the front inner hole 1A of the shaft cylinder 1 and the front portion 6B is guided by the inner hole 2B of the base 2, the lateral vibration is also restricted with respect to the base 2. The
[0010]
The chuck 7 for externally fitting the fastener 6 to the head is made of synthetic resin and, as shown in FIGS. 2 and 3, is divided into two from the front end to form an elastic piece 7A, and the front of the elastic piece 7A. As shown in FIG. 4, the head formed in the section includes a semi-circular maximum diameter portion 7 </ b> C formed at the tip of the core holding portion 7 </ b> B, and a core holding portion as shown in FIGS. 5 and 6. It is comprised from the protruding part 7D formed in the outer top part of 7B. The radius of curvature of the maximum diameter portion 7C is slightly smaller than the radius of curvature of the sliding hole 2C of the base 2 and larger than the radius of curvature of the inner hole 6D of the fastener 6. Further, the raised portion 7D of the chuck 7 is formed so as to be gradually higher as it goes forward in the longitudinal direction, and the cross-sectional shape of the raised portion 7D is formed in a semicircular shape with both sides cut, and the outer peripheral surface 7E The radius of curvature is formed slightly larger than the inner hole 6D of the fastener 6. Moreover, the raised portion 7D has the same radius of curvature at any position in the longitudinal direction.
[0011]
Further, as shown in FIG. 7, the inner hole 7F positioned inside the elastic piece 7A of the chuck 7 is formed in a tapered shape that gradually narrows the portion excluding the core holding portion 7B toward the front in the longitudinal direction.
[0012]
The shape of the core holding portion 7B of the chuck 7 is preferably substantially the same shape as the core 3 to be held, and as shown in FIG. 8, the elastic piece 7A bends in a mountain shape when the chuck 7 is closed. Assuming that the core holding part 7B is inclined so as to spread forward, the elastic piece 7A exactly matches the core 3 when bent, and the core 3 can be reliably held.
[0013]
Although not shown, a spring is stretched between the shaft cylinder 1 and the core tank 8, and the normal core tank 8 is urged rearward in the longitudinal direction. Therefore, the raised portion 7 </ b> D of the chuck 7 is brought into contact with the front end of the inner hole 6 </ b> D of the fastener 6. At this time, since the radius of curvature of the raised portion 7D of the chuck 7 is formed larger than the radius of curvature of the inner hole 6D of the fastener 6, as shown in FIG. 9, at two points 7G on both sides of the raised portion 7D. Contact with the inner hole 6 </ b> D of the fastener 6 prevents the lateral vibration of the chuck 7 located in the fastener 6.
[0014]
As shown in FIG. 10, the cylindrical rear portion 7H of the chuck 7 is formed with an outer flange portion 7I whose both sides are cut, and further, two protrusions 7J are formed behind the outer flange portion 7I. The protrusion 7J is formed such that the front end is formed vertically but the rear end is inclined. The reason for cutting both sides of the rear portion 7H is to provide a gate at this portion.
[0015]
In the method of press-fitting and connecting the chuck 7 to the core tank 8, the rear portion 7 </ b> H of the chuck 7 is first inserted into the inner hole 6 </ b> D of the fastener 6, and the fastener 6 is externally fitted to the head of the chuck 7. Further, the protruding portion 7J formed on the rear portion 7H of the chuck 7 is first inserted into the guide hole 8A of the core tank 8 formed to have a diameter larger than the outer diameter of the protruding portion 7J. The eight axes are substantially aligned. Next, the rear portion 7H of the chuck 7 is press-fitted into the front inner hole 8B of the core tank 8 which is thicker than the outer periphery 7K of the rear end of the chuck 7 and thinner than the protruding portion 7J, and is formed in the front inner hole 8B of the core tank 8. The protrusions 7J of the chuck 7 are fitted into the two recessed grooves 8C, respectively, and the chuck 7 and the core tank 8 are press-fitted and connected.
[0016]
Note that the difference between the radius of the protrusion 7J of the chuck 7 and the radius of the outer periphery 7K of the rear end of the chuck 7 is made larger than the difference between the radius of the guide hole 8A of the core tank 8 and the radius of the front inner hole 8B of the core tank 8. Thus, if the protruding portion 7J of the chuck 7 is inserted into the guide hole 8A of the lead tank 8, the rear end of the chuck 7 is necessarily inserted into the front inner hole 8B of the lead tank 8, so that the chuck 7 Even if the rear end is not aligned with the front inner hole 8B of the lead tank 8, it can be automatically inserted.
[0017]
The chuck 7 is made of polyacetal and is formed by injection molding with glass fiber in it. In addition, what was shape | molded is shape | molded in the state which the chuck | zipper 7 expanded.
[0018]
Further, since the radius of curvature of the maximum diameter portion 7C of the chuck 7 is formed slightly smaller than the radius of curvature of the sliding hole 2C of the base 2, the sliding hole 2C of the base 2 and the shaft when the chuck 7 is expanded. Since the centers coincide with each other and the lead holding part 7B of the chuck 7 is located at the center, the lead 3 in the lead tank 8 can surely fall inside the lead holding part 7B of the chuck 7.
[0019]
In addition, the radius of curvature of the maximum diameter portion 7C of the chuck 7 is formed larger than the radius of curvature of the inner hole 6D of the fastener 6, and the width of the maximum diameter portion 7C is formed larger than the diameter of the inner hole 6D of the fastener 6. Therefore, the head of the chuck 7 is pressed against the fastener 6 by the spring, and even when the chuck 7 is closed, there is no possibility that the head of the chuck 7 comes out of the fastener 6.
[0020]
Furthermore, as described above, the outer peripheral surface 7E of the raised portion 7D formed on the head of the chuck 7 is formed with the same radius of curvature at any position in the longitudinal direction of the cross-sectional shape. Therefore, even if the position of the fastener 6 that contacts the raised portion 7D of the chuck 7 is shifted back and forth, the chuck 7 and the fastener 6 are always contacted in the same state. That is, as shown in FIG. 9, even if the position of the fastener 6 is shifted back and forth, it always contacts the front end of the inner hole 6D of the fastener 6 at two points 7G on both sides of the raised portion 7D. The chuck 7 is always in a state in which the axial center coincides with the fastener 6 without swinging.
[0021]
11 and 12 show another embodiment of the present invention. The same members as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. A plurality of ribs 12D extending in the longitudinal direction are formed in the inner hole 12B of the base 12 at equal intervals in the circumferential direction, and the fastener 6 is interposed between the inner step 12A formed at the rear end of the rib 12D and the front end of the shaft tube 1. The outer casing 6A is loosely fitted in the longitudinal direction so as to be slidable as appropriate, and the front portion 6B of the fastener 6 is inserted inside the rib 12D so as to be slidable in the longitudinal direction.
[0022]
In this way, when the front portion 6B of the fastener 6 is guided by the rib 12D, there is little possibility of coming into contact with the fastener 6 even if the inner hole 12B of the base 12 has a dimensional variation, and the fastener 6 is surely slid. Move. Further, when the base 12 is injection-molded with a synthetic resin, there is no possibility that a recess is generated in the inner hole 12B.
[0023]
In the above embodiment, the synthetic resin chuck has been described. However, the present invention can sufficiently achieve the objective effect even in a metal chuck.
[0024]
【The invention's effect】
In the knock type mechanical pencil of the present invention described above, the fastener is guided by the inner hole of the base and the front inner hole of the shaft tube, so that the fastener can swing with respect to both the base and the shaft tube. Absent. Further, the guide hole of the lead tank is formed to have a larger diameter than the outer diameter of the chuck protrusion, and the chuck protrusion is determined by the difference between the radius of the guide hole of the lead tank and the radius of the front inner hole of the lead tank. By making the difference between the radius of the chuck and the radius of the outer periphery of the rear end of the chuck larger, if the protruding portion of the chuck is inserted into the guide hole of the core tank, the rear end of the chuck will inevitably become the front inner hole of the core tank. Since it is inserted, it can be automatically inserted without having to align the rear end of the chuck with the front inner hole of the lead tank. Accordingly, there is no fear that the chuck is bent and attached, and the press-fit connection between the chuck and the lead tank can be surely performed and the followability of the lead can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part showing a knock mechanical pencil of the present invention.
FIG. 2 is a front view showing a chuck in the knock mechanical pencil of the present invention.
FIG. 3 is a plan view showing a chuck in the knock mechanical pencil of the present invention.
FIG. 4 is an end view showing the front end of the chuck in the knock mechanical pencil of the present invention.
5 is a cross-sectional view taken along line AA in FIG. 2. FIG.
6 is a cross-sectional view taken along line BB in FIG.
FIG. 7 is a bottom view of the main part showing the inside of the front part of the elastic piece in the chuck.
FIG. 8 is a cross-sectional view showing a state where the chuck is closed and the core is held.
FIG. 9 is a cross-sectional view showing a state where the front end of the fastener is in contact with the raised portion of the chuck in the knock mechanical pencil of the present invention.
10 is a cross-sectional view taken along the line CC in FIG. 2. FIG.
FIG. 11 is a cross-sectional view of the main part showing another embodiment of the knock mechanical pencil in the present invention.
12 is a cross-sectional view taken along line AA in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shaft cylinder 1A Front inner hole 2 of shaft cylinder 1 Base 2B Inner hole 3 of core 2 Core 6 Fastener 6A Outer flange 6B of fastener 6 Front part 6C of fastener 6 Rear part 7 of fastener 6 Chuck 7H Rear part 8 core tank 8B front inner hole 12 of core tank 8 base 12D rib of base 12

Claims (2)

In a knock-type mechanical pencil that feeds the lead by advancing the chuck, a ridge is formed at the rear of the chuck and a front inner hole is formed at the front of the lead tank, and at the front of the front inner hole of the lead tank. The guide hole is formed with a diameter larger than the outer diameter of the chuck ridge, and the radius of the chuck ridge is determined by the difference between the radius of the guide hole of the core tank and the radius of the front inner hole of the core tank. And the rear end outer radius of the chuck is large, the chuck is inserted from the front of the shaft cylinder, the core tank is inserted from the rear of the shaft cylinder, and the ridge formed at the rear of the chuck in the shaft cylinder Is press-fitted and connected to the front inner hole of the core tank, and the outer shell of the fastener is loosely fitted between the inner stage of the base and the shaft tube so as to be slidable appropriately in the longitudinal direction. The rear part of the fastener is slidably inserted in the inner hole of the Knock-type mechanical pencil, characterized in that in the front bore of the barrel and slidably inserted in the longitudinal direction. 2. A knock type mechanical pencil according to claim 1, wherein ribs extending in the longitudinal direction are formed in the inner hole of the base at equal intervals in the circumferential direction, and lateral vibration of the front portion of the fastener is regulated by the ribs. .

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