JPH0958179A - Mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To omit a component and to reduce the cost by forming a first lead grip for gripping a lead sandwiched between the tapered surface of a barrel and a chuck for gripping the lead, and a second lead grip for gripping the lead sandwiched between the engaging parts provided in the end inner hole of a lead case. SOLUTION: When one side piece 3b is drawn rearward and separated, a slider 3 is forwarded, a lead 12 is drawn from a chuck 5 to protrude from the end of a guide pipe 3a. When the rear end of the lead 12 is removed from the chuck 5, it becomes impossible to feed. Then, when the rear end of the rear barrel 7 is knocked to the barrel 1 to forward a lead case 6, the second engaging part 6a at the end of the case 6 is brought into contact with the engaging part 5g. Thereafter, only the case 6 is forwarded, the end of the chuck 5 is expanded at the tapered part 6c at a fulcrum 5i, and the lead 12 becomes introducible. When the knocking is released from this state, chuck 5 is retracted while the gripping of the lead 12 remains released, and it is again knocked to sequentially feed the lead 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a mechanical pencil that can be provided at low cost.

[0002]

2. Description of the Related Art Conventionally, there is known a mechanical pencil in which a rear end of a shaft cylinder is knocked to extend a lead. Usually, this type of mechanical pencil is provided with a fastener for pinching the chuck to grip the lead so that the fastener cooperates with the chuck at the tip of the barrel. There is also known a mechanical pencil in which a rear shaft having a built-in eraser feeding mechanism is attached to the rear end of a barrel and the rear shaft is rotated to allow a large-diameter eraser to be retracted from the rear end. This product has the trouble of frequently knocking the rear end together with the consumption of the core. In addition, there is an annoyance that the eraser projecting when knocking is stored in the rear shaft. Further, when knocked in the protruding state, there is a problem that the finger becomes dirty, or the oil of the finger is transferred to the end surface of the eraser to deteriorate the erasability. Further, it is known that the core is automatically fed by pressing the guide pipe at the tip, but there is a problem that the structure is complicated and expensive. Although there is a simplified structure, it is a disposable type and it is difficult or difficult to replenish the core.

[0003]

DISCLOSURE OF THE INVENTION The present invention makes it possible to provide an inexpensive mechanical pencil by omitting parts as compared with the conventional example.

[0004]

In a mechanical pencil of the present invention devised to achieve the above object, a tip shaft having a holding chuck is fixed to the tip of the barrel, and the tip pencil is provided in the inner bore of the barrel. A chuck that has a tapered surface and grips the core by the clamping pressure, and a core case that engages with the outer periphery of the rear end of the chuck and connects the chuck so that it can move back and forth are connected to the rear of the shaft cylinder via a return spring. In a mechanical pencil configured to be urged and prevented from coming off, the chuck has a front outer peripheral portion that is clamped by a tapered surface of the shaft cylinder to grip a lead.
Of the core case is formed in the axial center part, and the tip of the core case is inserted into the rear outer peripheral part, and is pinched by the first engaging portion provided in the inner hole at the tip of the core case when the core case is advanced. A second core gripping portion for appropriately gripping the core by forming a second core gripping portion on the shaft center portion, and further behind the second core gripping portion, is engaged with a second engaging portion provided behind the first engaging portion of the core case. The mechanical pencil is formed with an engaging portion that moves the chuck forward and backward together.

Further, in the above mechanical pencil, a slit is provided in the side surface of the front end of the front shaft, and a guide pipe protruding appropriately from the tip of the front shaft, a holding chuck for frictionally engaging the core, and the slit are appropriately connected. A mechanical pencil in which a slider integrally provided with a protruding piece is provided so as to be movable back and forth within a front shaft, and a spring is biased between the rear of the slider and the front of the chuck.

Further, in the above mechanical pencil, the lead case is prevented from rotating with respect to the barrel, and a slit is formed on the rear side surface of the barrel portion of the lead case extending to the rear of the barrel, and an eraser is sandwiched in the rear. With an elastic piece to be attached, an eraser holder having a protrusion on the side surface of the front cylinder part can move back and forth by sandwiching an eraser, and the protrusion and the elastic piece are fitted and inserted into the slits, respectively, while The rear shaft having a spiral groove formed in the inner hole is externally mounted on the cylindrical portion, the rear shaft is attached to the cylindrical portion only to rotate, and the protrusion of the eraser holder is fitted into the spiral groove to form a shaft cylinder. On the other hand, by rotating the rear shaft, the eraser is a mechanical pencil that can be retracted from the rear end of the rear shaft.

[0007]

FIG. 1 shows a first embodiment of the present invention.
First, the slider 3 is fitted in the inner hole of the front shaft 2 so as to be movable back and forth. A guide pipe 3a that allows the core to be inserted is fixed to the front side of the slider 3, and a holding chuck 4 made of rubber or the like that allows the core to be appropriately frictionally engaged and inserted is fixed to the rear side. It is also possible to form the slider as a resin molded product and form the holding chuck integrally with the slider as an elastically displaceable engaging portion. A piece 3b is provided at an appropriate position on the circumference approximately in the middle of the slider 3.
The b is elastically fitted into a slit 2b formed in the side surface of the front shaft 2, and the outer surface of the b is slightly projected from the side surface of the front shaft 2.

A cylinder portion 1c, which is the tip of the shaft cylinder 1, is fixed to the rear end hole of the front shaft 2 behind the holding chuck 4.
Further, a tapered surface 1f is formed in the inner hole of the cylindrical portion 1c, and an inner step portion 1d is formed at the tip thereof. Further, a rib or the like is formed at a required position in a rear portion inner hole of the cylinder portion 1c of the shaft cylinder 1, and a step portion 1a is provided at a rear end thereof. Also, the barrel 1
A rectangular window portion 1b is formed on the side surface of the rear end portion of the.

A halved chuck 5 is fitted in advance on the tapered surface 1f, and a spherical or rounded projection 5b is formed on the outer periphery of the front portion of the chuck 5, and the axial center of that portion is formed. A first lead gripping portion 5a is formed on the portion.
Further, when the projection 5b comes into contact with the tapered surface 1f and the chuck 5 is biased rearward, the pressure is clamped in the axial direction and the first
The core 12 is gripped by the core gripping portion 5a. Further, a recess 5d is formed behind the protrusion 5b, and a shaft 5e is formed further in the rear. Further, the outer peripheral portion of the front end of the shaft portion 5e is formed as an engaging portion 5f, and the rear portion thereof is slightly reduced in diameter to form a convex engaging portion 5g on the outer peripheral portion of the rear end. A second lead gripping portion 5h is formed at the axial center of the engaging portion 5f.

FIG. 2 shows a second embodiment of the present invention, which is different from the first embodiment in that only one main part is different and will be described here. In this device, a recess 20b is formed on the outer peripheral portion of the chuck 20 corresponding to the first lead gripping portion 20a, and a ball 21 is loosely fitted in the recess 20b.
1 is pressed against the tapered surface 1f so as to grip the core. Although the second embodiment is less costly than the first embodiment, it is excellent in quality stability and service life.

On the other hand, the core case 6 is a cylindrical body, and a convex first engaging portion 6a is formed in the inner hole portion at the front end, and a convex second engaging portion 6b is formed behind it. ing. Further, a taper portion 6c is provided further rearward of the second engaging portion 6b. Further, a cylindrical portion 6e having a stepped portion 6d and having a diameter increased rearward is provided substantially in the middle in the longitudinal direction of the cylindrical body, and a protruding locking portion 6i is formed on the outer periphery of the front portion of the cylindrical portion 6e. A locking portion 6f that bulges in a circumferential shape is formed on the outer periphery of the rear portion. or,
A longitudinal slit 6g communicating with the rear end is formed on the rear side surface of the locking portion 6f.

The core case 6 has a return spring 10 mounted on the outer periphery of the front end of the cylindrical body.
The rear end of 0 is inserted from the rear end of the barrel 1 with the rear end thereof in contact with the step 6d, the front end of the return spring 10 is brought into contact with the step 1a of the barrel 1, and the core case Of the locking portion 6i is elastically fitted into the window portion 1b of the shaft cylinder so that the rear end of the locking portion 6i abuts on the rear end of the window portion 1b, and the core case 6 moves rearward with respect to the shaft cylinder 1. It is urged, and the rotation is stopped and the retainer is prevented in a state where the axis can be changed appropriately. At that time, the inner hole of the tip portion of the lead case 6 is located behind the chuck 5 and the shaft portion 5e.
It is made in a state where it is exteriorized. Further, the front shaft 2 is fixed to the cylinder portion 1c at the tip of the shaft cylinder while the spring 9 is biased between the rear portion of the slider 3 and the tip step portion 5c in front of the chuck.

The slit 6g portion of the cylindrical portion 6e of the core case, together with the hole for inserting the eraser 11, has a slanted rear end portion 6 which substantially fits into a slanted contact portion 7c of the rear shaft 7 which will be described later.
h. Further, the eraser holder 8 has an elastic piece 8c which holds the rear end of the eraser 11 between the rear side and a locking projection 8d which appropriately bites into the outer surface of the eraser 11 on its inner surface,
On the side surface of the front cylindrical portion 8a, a protrusion 8 is provided coaxially with the elastic piece 8c.
b is provided. Also, the slit 6g of the core case
Insert the eraser holder 8 into the hole of the
The elastic piece 8c is fitted into the slit 6g, and the eraser 11 is fixed to the rear end of the eraser holder 8.

The rear shaft 7 described above has a large-diameter hole portion to the exterior of the shaft cylinder 1, and a step portion 7d is provided at the rear end of the hole portion to reduce the diameter to the rear. Is connected to the rear end. In addition, the circumferential locking groove 7b is formed in the hole slightly rearward of the step 7d.
Is formed, and further the spiral groove 7a is formed to reach the rear end substantially rearward. Further, the abutting portion 7c is provided at the rear end of the spiral groove 7a, and a hole through which the eraser 11 can appear and disappear is opened.

As described above, the rear shaft 7 is exteriorly mounted from the rear end of the tubular portion 6e of the core case 6, and the engaging portion 6f of the tubular portion is fitted into the engaging groove 7b by mutual elastic deformation. At this time, the projection 8b is fitted into the spiral groove 7a in a state where the front end of the eraser holder 8 is in contact with the step 6j at the front end of the slit 6g. (To be precise, the projection 8b and the spiral groove 7a are made to come into contact with each other while the rear shaft 7 is slightly rotated with respect to the tubular portion 6e.) As described above, the rear end 6h of the core case 6 contacts the rear shaft 7 with the contact portion 7c. The rear shaft 7 is rotatably secured to the rear shaft 7 in a state of being substantially in contact with The slit 6g of the tubular portion 6e of the lead case is delicate and easily deformed, but the inward deformation is prevented by the contact between the inclined contact portion 7c and the rear end portion 6h. To do.

[0016]

First, when the piece 3b is pulled backward with a finger and separated, the slider 3 moves back and forth, and the core 12 is projected from the tip of the guide pipe 3a by an appropriate amount to enable writing. When the core 12 is consumed by writing and pulls the piece 3b rearward with a finger and releases it, the slider 3 moves forward by the action of the spring 9,
At the same time, the lead 12 pulls the lead out of the chuck 5 each time by the frictional engagement force of the holding chuck 4. The chuck 5 releases the lead 12 with a weak force in the forward direction and holds it backward with a sufficient force against the writing pressure. Further, if the rear end of the lead 12 comes off the chuck 5 as the lead 12 is consumed, it cannot be fed out.

From the state shown in FIG. 1, when the rear end of the rear shaft 7 is knocked against the barrel 1 to move the lead case 6 forward, the second engaging portion 6a at the tip of the lead case is located behind the chuck 5. When the chuck 5 comes into contact with the end engaging portion 5g and further advances, the chuck 5 interlocks and advances, and the tip of the chuck 5 comes into contact with the inner step portion 1d at the tip of the barrel 1 to prevent the chuck 5 from advancing. 6 moves forward, the second engaging portion 6b elastically rides over the engaging portion 5g of the chuck 5 and is positioned in the front portion thereof, and the first engaging portion 6a of the lead case is recessed 5d of the chuck. Located in
The rear end of the chuck 5 is narrowed by the tapered portion 6c of the lead case, and the tip of the split chuck 5 expands to the fulcrum 5i, and the first lead gripping portion 5a and the second lead gripping portion 5h are opened.
Is released so that the core 12 can be inserted. At that time, the step portion 7d of the rear shaft 7 comes into contact with the rear end of the barrel 1. When the knock is released from this state, the chuck 5 retracts with the lead gripping being released, and returns to the state of FIG.

When knocked again, the first engaging portion 6a of the lead case presses the engaging portion 5f of the chuck 5 and the lead 12 is held by the second lead holding portion 5h of the chuck, and the front end of the chuck 5 is held. The lead 12 advances together with the chuck until it comes into contact with the inner step portion 1d at the tip of the barrel. When the lead case 6 is further advanced, the lead gripping portion of the chuck 5 is released as in the above, and when the knock is released, only the chuck is retracted while the lead gripping portion is opened. Hereinafter, the lead 12 is sequentially fed out repeatedly.
The operation of the holding chuck 4 is similar to that of the conventional example.

Next, when the rear shaft 7 is rotated left and right with respect to the shaft cylinder 1, the eraser 11 is projected and retracted from the rear end hole of the rear shaft 7. Basically, with the eraser 11 retracted, the rear end of the rear shaft 7 is knocked and the lead is extended. Also, the eraser 11 is exhausted,
When the eraser holder 8 reaches the backward limit, a new eraser is replaced.

[0020]

The construction and operation of the mechanical pencil of the present invention are as described above, and the parts can be omitted to provide the mechanical pencil at a low cost. Also, if you make it a mechanical pencil that pulls out the core by simply pulling one part with your fingertips without changing the writing instrument,
Not only does the conventional trouble of frequent knocking be eliminated, but the structure is simple and the cost is low.
In addition, if it is a mechanical pencil with a large diameter and a long eraser can be fed out, it is not only convenient as a mechanical pencil for writing and erasing frequently but also as a mechanical pencil for examinees, it can further simplify the structure, so the effect of making it cheaper is great .

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a mechanical pencil according to a first embodiment of the present invention.

FIG. 2 shows a vertical sectional view of a mechanical pencil according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Shaft cylinder 1a Step part 1b Window part 1c Tube part 1d Inner step part 1e Locking part 1f Tapered surface 2 Tip shaft 2a Locking groove 2b Slit 2c Step part 2d Hole part 3 Slider 3a Guide pipe 3b One-sided part 4 Holding chuck 5 Chuck 5a First core gripping part 5b Projection part 5c Tip step part 5d Recessed part 5e Shaft part 5f Engagement part 5g Engagement part 5h Second core gripping part 5i Support point 6 Core case 6a First engagement part 6b Second Engaging part 6c taper part 6d step part 6e tubular part 6f locking part 6g slit 6h rear end part 6i locking part 6j step part 7 rear shaft 7a spiral groove 7b locking groove 7c contact part 7d step part 8 eraser holder 8a Cylindrical part 8b Protrusion 8c Elastic piece 8d Locking protrusion 9 Spring 10 Return spring 11 Eraser 12 Core 20 Chuck 20a First core gripping part 20b Recess 21 Ball

Claims (5)

[Claims] 1. A chuck in which a front shaft having a holding chuck is fixed to the front end of a shaft cylinder, a chuck having a tapered surface in an inner hole at the front end of the shaft cylinder to grip a core by the clamping pressure, and a rear end outer circumference of the chuck. In a mechanical pencil constructed such that a lead case that engages with a portion and connects a chuck so as to be movable back and forth is urged rearward against a shaft cylinder via a return spring and prevented from coming off.
The chuck has a first core gripping portion formed on the shaft center portion, the first core gripping portion having a front outer peripheral portion clamped by the tapered surface of the shaft cylinder and gripping a core, and a tip of the core case fitted and inserted in a rear outer peripheral portion. A second core gripping portion is formed in the shaft center portion, which is clamped by a first engaging portion provided in a distal end inner hole of the core case by the advancement of the core case to appropriately grip the core, and further rearward thereof. And a mechanical pencil formed with an engaging portion that engages with a second engaging portion provided behind the first engaging portion of the lead case to advance and retract the chuck. 2. A slit is formed in the side surface of the tip of the front shaft,
A slider integrally provided with a guide pipe that appropriately protrudes from the tip of the tip shaft, a holding chuck that frictionally engages the core, and a piece that appropriately protrudes from the slit is provided so as to be movable back and forth within the tip shaft. The mechanical pencil according to claim 1, wherein a spring is biased between the rear side and the front side of the chuck. 3. A projection having a spherical surface or a rounded surface is formed on the outer peripheral surface of the chuck, which is pressed by the tapered surface of the shaft cylinder, and the projection is in contact with the tapered surface. The mechanical pencil according to claim 1 or 2. 4. A recess is formed in the outer peripheral surface of the chuck that is pressed by the tapered surface of the shaft cylinder, and a ball is loosely fitted in the recess so that the ball abuts the tapered surface. The mechanical pencil according to items 1 and 2. 5. The core case is prevented from rotating with respect to the shaft cylinder, and a slit is formed on the rear side surface of the cylinder part of the core case extending to the rear of the shaft cylinder, and an elastic piece for sandwiching an eraser is provided on the rear side. An eraser holder with a protrusion on the side surface of the front cylinder part can be moved back and forth by sandwiching the eraser, and the protrusion and elastic piece are fitted and inserted into the slits respectively, while a spiral groove is formed in the inner hole. The rear shaft is externally mounted on the cylindrical portion, the rear shaft is rotatably attached to the cylindrical portion, and the protrusion of the eraser holder is fitted in the spiral groove to rotate the rear shaft with respect to the cylindrical barrel. The mechanical pencil according to any one of claims 1 to 4, wherein the eraser can be retracted from the rear end of the rear shaft.