JP2003112496A - Mechanical pencil and lead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical pencil which is free of the problem that a lead in a state of a remnant rotates and this brings about a bad feeling of writing, which eliminates waste by shortening the remnant lead extremely and is excellent in usability and of which the unit price is low. SOLUTION: In regard to the mechanical pencil wherein the lead is held and let out with the forward and backward movement of a chuck disposed in the front of a holder tube, and to the lead, the lead has engaging faces in the shape of appropriate indentations formed in the opposite end faces in the axial direction, and the rear end of the remnant lead and the front end of a supplied lead face each other and come into contact with each other by the mutual engaging faces, so as to enable checking of rotation. A slider is inserted into the inner hole of a tip part provided at the front end of the holder tube, in a state wherein the fore end part of the slider projects from the front end of the tip part, and a holding chuck is so provided as to be directed almost to the front end of the inner hole part of the slider. Besides, the outer peripheral part of the slider is so engaged with the inner peripheral part of the tip part as to move forward and backward at prescribed spaces, and the lead holding force of the holding chuck is set to be stronger than the engaging force of the slider.

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 which can be used until the residual core becomes as small as possible.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show a conventional mechanical pencil and lead. As shown in the figure, a chuck 20 is installed at the tip of the shaft cylinder 16 via a shaft joint 18 by fitting a fastener 21 on the outer periphery of the grip portion, and a core case 19 and a shaft fixed to the rear end of the chuck 20. The chuck 20 is clamped by the chuck spring 23 urged between the cylinder 16 and the cylinder 21.
The supply core 14b is gripped by being clamped by. A slider 22 is fixed to the tip of the tip 17 attached to the tip of the barrel 16. The slider 22 includes a tip pipe 22b in front of the core guide shaft 22a and an elastic material such as rubber in the back. The holding chuck 22c is fixed,
The residual core 14a penetrates the holding chuck 22c and projects from the tip pipe 22b.

When the chuck 20 is knocked forward from this state and the chuck 20 is advanced, since the chuck 20 is tightened by the fastener 21, the supply core 14b is advanced while being held. When the fastener is further advanced, the fastener 21 comes into contact with the step portion 17a of the tip portion 17 and only the chuck advances, so that the gripping of the lead is released and the front end of the lead comes into contact with the rear end of the residual lead 14a. When the knock is released from that state, the chuck retracts with the core stopped, but from the time when the grip portion of the chuck starts to engage the fastener 21, the chuck frictionally engages the core and the core is slightly retracted. The grip is completed with. That is, when the rear end of the residual core 14a is disengaged from the grip of the chuck 20, the front end of the supply core 14b contacts the rear end of the residual core 14a at the next knock, but the front end of the supply core 14b contacts the holding chuck 22c. Since they are not engaged with each other, when the chuck 20 is retracted, the chuck is tightened by the fastener 21, and the lead engages with the chuck slightly before and the lead is slightly retracted.
A gap 24 is created between the 4b.

Therefore, when a writing pressure is applied to the front end of the residual core 14a, core gap diving occurs. When that happens, the writing feel is poor, and for a while the core dive is repeated with each knock. Therefore, usually, knocking is repeated and the remaining lead is often discharged. In that case, there is a problem that the length between the front end of the chuck gripping portion and the front end of the tip pipe is wasted as a residual core. Its length varies depending on the design, but is usually 7
It is about mm to 12 mm. Even when used with patience, the core removed from the chuck is only lightly held by the core holding chuck. Therefore, when writing with this remnant core, the core rotates and the writing feeling is poor,
Usually, knocking is repeated and the remaining core is discharged. Also, a method of strongly setting the holding force of the holding chuck in the core passing direction has been proposed, but there are difficult problems such as member accuracy and durability.

Further, a mouth portion is provided at the front end of the shaft cylinder, and a core case inside the shaft cylinder and a rear chuck in which a fastener is fitted around the outer periphery of the grip portion at the front end portion of the core case can be moved back and forth by a spring. A front chuck is provided in front of this rear chuck so as to interlock through a joint,
There is known a mechanical pencil called a top chuck or a double chuck in which a grip portion of the front chuck is engaged with a front end hole of a mouth portion to grip a lead. In this case, the front chuck can hold a residual core having a length of about 1 mm, and there is no waste of the core. However, since the structure is complicated, it is difficult to provide it as a low-cost mechanical pencil. Further, since the tip is a chuck, there is a problem that it is difficult to draw a wire by hitting it with a ruler.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the problem that when writing is performed in the residual core state, the core rotates and the writing feeling deteriorates. Further, it is possible to provide a mechanical pencil that is extremely easy to use and has a low unit price, while reducing the amount of residual core extremely to eliminate waste.

[0007]

The present invention has the following constitution in order to achieve the above object. A mechanical pencil and a lead according to the invention described in claim 1 are a mechanical pencil and a lead, which are configured such that the lead is gripped by the forward and backward movement of a chuck arranged in front of a barrel and the lead is extended. The core is
Concave and convex engaging surfaces are formed on both end surfaces in the axial direction.

The mechanical pencil and the lead according to the invention described in claim 2 are the mechanical pencil and the lead according to claim 1, wherein the tip portion is in the inner hole of the tip portion provided at the front end of the barrel. The holding chuck is provided toward the front end of the inner hole of the slider, which is inserted so as to be projected from the front end of the portion.
Further, the outer peripheral portion of the slider is engaged with the inner peripheral portion of the mouth portion so as to advance and retreat at a predetermined interval, and the core holding force of the holding chuck is strongly set with respect to the engaging force of the slider. It becomes.

[0009]

EXAMPLES Examples will be described with reference to the drawings.
FIG. 1 shows a knock type mechanical pencil according to an embodiment of the present invention, in which a chuck 8 is fitted with a fastener 11 on the outer periphery of a tip core gripping portion thereof, and then a shaft joint 1 from the rear end side thereof.
0 is inserted into the shaft center hole, the shaft joint 10 is inserted into the shaft center hole of the shaft cylinder 1, and the locking portion 8b at the rear end of the chuck 8 is connected to the connecting hole provided in the shaft portion 4a at the front end of the core case 4. It is locked. Further, a chuck spring 12 is laid between the step portion 4b provided at the front of the core case 4 and the rear end of the shaft coupling 10 so as to pull the chuck 8 rearward. Further, the front part of the chuck 8 is composed of a shaft part which is capable of expanding and contracting and which is divided into two or three parts.

The slider 9 is fixed to a holding chuck 9b made of rubber or the like, which is inserted through the core toward the front end of the inner hole of the tip pipe 9a, and which is frictionally engaged with the slider 9 via a step 9d behind the tip pipe 9a. The shaft portion 9c is integrally provided, and a convex portion 9e is formed on the outer periphery of the shaft portion 9c.

Further, the inner peripheral portion 3e of the tip portion 3 (in the embodiment,
A front end step portion 3b is formed at the front end (corresponding to the end surface of the rib formed at a plurality of locations), a step portion 3a is formed at the rear side thereof slightly on the side of slightly reduced diameter, and further at the rear side thereof on the enlarged side. A step portion 3d is formed at the bottom. The slider 9 has a shaft portion 9c.
The rear end of the convex portion 9e formed on the outer periphery of the tip end pipe 9a is inserted by utilizing the elastic displacement between them so that the rear end of the convex portion 9e is located in front of the stepped portion 3a formed on the inner peripheral portion of the mouth. Mouth 3
Is projected from the front end of. Further, at the forward position where the step portion 9d of the slider abuts the tip step portion 3b and the retracted position where the rear end of the convex portion 9e of the slider abuts the step portion 3a, the slider 9 advances and retreats at a predetermined interval with respect to the tip portion 3. To do. Further, the engaging portions provided on the shaft portion and the mouth portion may have a locking relationship between the groove portion formed on one side and the convex portion formed on the other side, and the engaging shape is not limited. Further, the slider 9 may be provided not only as one body but also as the tip pipe 9a (for example, metal) and the outer cylinder portion 9c provided separately. If the slider is a resin molded product, the holding chuck can be formed of an integral elastic piece.

The tip portion 3 is attached to the shaft portion 1a at the front end of the shaft cylinder 1 by means such as screwing, and the flange portion 10a provided at the front end of the shaft coupling 10 is connected to the front end of the shaft portion 1a of the shaft cylinder. The shaft coupling 1 is sandwiched between the inner end portion of the tip portion 3 and
0 is fixed to the barrel 1.

Further, from the state shown in FIG.
Moves forward, the core gripping state of the chuck 8 is released, and the core is fed out. (See FIG. 3) It should be noted that the interval 15a shown in FIG. By the way, as shown in FIG. 7, the core 13 which is the gist of the present invention has, on both end faces, engaging surfaces 26a,
6b is formed.

Further, when the lead is sequentially fed out and the rear end of the lead is separated from the front end of the chuck, that is, the rear end of the residual lead 13a is located in front of the chuck 8, and the front end of the supply lead 13b is located at the residual lead 13a. The remnant core 13a when in contact with the rear end of the
The engagement surface at the rear end and the engagement surface at the front end of the supply core 13b are in contact with each other. In this state, when the rear end of the residual core 13a is located behind the core gripping portion of the chuck 8, the supply core 13b located behind the residual core 13a is driven by its own weight and a slight swing. Further, when the rear end of the residual core 13a is located in front of the chuck 8 and there is no subsequent supply core 13b and the supply core 13b is supplied later, when the chuck 8 advances and the core gripping portion is released, the supply core 13a is released. 13b falls by its own weight, and the engagement surface at the front end comes into contact with the engagement surface at the rear end of the residual core 13a.

When the chuck 8 is retracted from the advanced state and the chuck 8 engages the fastener 11 to start gripping the core, the chuck 8 is retracted together with the chuck while the core is engaged with the chuck to move the core of the chuck. The grip is completed. Therefore, as shown in FIG. 4, a gap 25 is formed between the engagement surface at the rear end of the residual core 13a and the engagement surface at the front end of the supply core 13b, but the writing pressure should be applied to the distal end of the residual core 13a. As a result, the slider 9 retracts, and the engagement surface at the rear end of the residual core 13a comes into contact with and abuts against the engagement surface at the front end of the supply core 13b, and no core diving occurs. This is achieved by setting the core holding force of the holding chuck 9b to be stronger than the engaging force of the slider 9. Further, it is desirable that the slider 9 is preferably prevented from rotating with respect to the tip portion 3.

Since the above-mentioned core 13 has different engaging surfaces at both ends, the supply core must always be housed in the core case with the same engaging surfaces. As an improvement, the core 27 and the core 28 shown in FIGS. 8 and 9 have engaging surfaces 27a and 28a having the same shape at both ends, and are shaped so as to be compliant with each other. The shape of the engaging surface is devised to be simple and easy to meet due to design considerations.

[0017]

By repeatedly knocking and releasing the cap 5 from the state shown in FIGS. 1 and 2, the chuck 8 is moved back and forth in conjunction with the lead case 4 in the same manner as a normal mechanical pencil so that the lead is the tip pipe. It is fed from the front end of 9a. That is, the chuck 8 contacts the stepped portion 3b of the tip portion 3 with the stepped portion 9d of the slider 9 to prevent the slider 9 from advancing relative to the tip portion 3, and the chuck 8 is further advanced to tighten the fastener 11. The lead is fed by coming into contact with the step portion 3d and further moving forward to release the lead gripping state of the chuck 8. The lead-out amount of the lead is approximately the size of the interval 15a at which the front end of the fastener 11 abuts on the stepped portion 3d of the mouth end portion.

When the lead is consumed with writing, the trailing end of the lead comes off the lead gripping portion of the chuck 8 and becomes the residual lead 13a. Further, the next lead from the lead case 4 is sent to the chuck 8 as the supply lead 13b. FIG. 4 shows the residual core 1 in the slider 9.
3a is located, and the supply core 13b gripped by the chuck 8 is located behind it. When the chuck 8 is advanced in this state to release the lead gripping, the engagement surface at the front end of the supply lead 13b comes into contact with and abuts on the engagement surface at the rear end of the residual lead 13a. When the chuck 8 is retracted and the chuck 8 engages with the fastener 11 to start the core gripping, the core is retracted together with the chuck while the core is engaged with the chuck and the core gripping of the chuck is completed.
As shown in the figure, a gap 25 is formed between the rear end of the residual core 13a and the front end of the supply core 13b.

However, by applying a writing pressure to the tip of the residual core 13a, the slider 9 retracts, and the engagement surface at the rear end of the residual core 13a comes into contact with and abuts against the engagement surface at the front end of the supply core 13b. Until the rear end of the residual core 13a comes off the holding chuck 9b, even if pressure is applied to the front end of the core, there is no core diving and the feeling of writing is good. In addition, the engaging surface at the rear end of the residual core 13a has the supply core 13b.
Since it engages with the engaging surface at the front end, the core rotates, and there is no problem that the writing feeling deteriorates. Further, by providing the holding chuck at the front end of the inner hole of the tip pipe as much as possible, the length of the unrewritable remnant core can be shortened.

Further, the convex portion 9e formed on the outer periphery of the shaft portion 9c of the slider and the inner peripheral portion 3e of the mouth portion are frictionally engaged or engaged with each other by providing a locking portion between them to engage and disengage. By setting the engaging force to be larger than the force with which the chuck pulls the lead between when the chuck starts gripping and when it finishes, the position where the slider always moves forward with respect to the tip of the lead when the lead is pulled out. The lead-out amount is substantially defined by the interval 15a. Further, when the lead is fed out in the residual core state (see FIG. 4), in order to prevent the core from diving even when a writing pressure is applied to the gap 25 between the residual core 13a and the supply core 13b, the slider shaft portion and the tip portion It is necessary to make the core holding force of the holding chuck 9b larger than the engaging force with the inner peripheral portion.

That is, the force with which the shaft portion of the slider and the inner peripheral portion of the tip portion are engaged with each other is strong with respect to the force with which the chuck pulls the lead between the start and end of the lead gripping, and the tip portion The core holding force of the holding chuck is set to be stronger than the force of engaging with the inner peripheral portion of the.

Further, it is necessary for the slider to be engaged in a substantially stationary state at the most advanced position of the tip portion with respect to the force with which the chuck pulls the lead until the chuck starts and finishes gripping the lead. .. Further, in order to write with good pen feeling in the residual core state, it is necessary for the slider 9 to slide smoothly on the inner peripheral portion of the mouth portion in order to fill the gap 25. As a device for that, the convex portion 9e is formed to be elastically displaceable so that the engaging force can be set within a very limited range, or the convex portion 9e is gently engaged with the inner circumference of the mouth end portion at the most advanced position of the slider. A step is provided to allow sliding without feeling a catch when the slider starts moving backward.

[0023]

The structure and operation of the present invention are as described above, and there is no problem that when writing is carried out in the state of the residual core, the core rotates and the writing feeling deteriorates. In addition, the unrewritable residual core is extremely short and the core is not wasted, which is economical. In addition, since a small amount of residual core is discharged, it can be performed with a small number of knocks, the troublesomeness can be extremely reduced, the usability is simple, and the structure is simple, so that it is possible to provide a low-price pipe slide type mechanical pencil.

[Brief description of drawings]

FIG. 1 shows a vertical half sectional view of an entire mechanical pencil that is an embodiment of the present invention.

FIG. 2 is a half cross-sectional view showing an enlarged main part of the mechanical pencil of the present invention, showing a state in which the chuck is retracted.

FIG. 3 is a half cross-sectional view showing an enlarged main part of the mechanical pencil of the present invention, showing a state in which the chuck is most advanced.

FIG. 4 is a half cross-sectional view showing an enlarged main part of the mechanical pencil of the present invention, showing a state in which the chuck is retracted in a residual core state.

FIG. 5 is a half cross-sectional view showing an enlarged main part of a conventional mechanical pencil.

FIG. 6 is a view showing a conventional core.

FIG. 7 is a diagram showing Embodiment 1 of the core which is the gist of the present invention.

FIG. 8 is a view showing a second embodiment of the core which is the gist of the present invention.

FIG. 9 is a view showing a third embodiment of the core which is the gist of the present invention.

[Explanation of symbols]

1-axis cylinder 1a Shaft 2 grip 3 mouth 3a step 3b Tip step 3c Shaft 3d step 3e Inner circumference 4-core case 4a Shaft 4b step 5 caps 6 clips 7 eraser 8 chuck 8a lead gripping part 8b Locking part 9 slider 9a Tip pipe 9b holding chuck 9c Shaft 9d step 9e convex part 10 Shaft joint 10a Flange part 11 fasteners 12 Chuck spring 13 cores (Embodiment 1) 13a remnant core 13b Supply core 14-core (conventional example) 14a Remaining core 14b Supply core 15a interval 16-axis cylinder 17 Mouth 17a step 18 Shaft joint 19-core case 20 chuck 20a locking part 21 Fastener 22 Slider 22a core guide shaft 22b Tip pipe 22c holding chuck 23 Chuck spring 24 gaps 25 gap 26a engagement surface 26b engagement surface 27 cores (Embodiment 2) 27a engagement surface 28 cores (Embodiment 3) 28a engagement surface

Claims (2)

[Claims] 1. A mechanical pencil and a lead, wherein the chuck is arranged in front of a shaft cylinder to grip and lead the lead by forward and backward movements. The lead is provided on both end surfaces in the axial direction. It is characterized in that an engaging surface having a concave-convex shape is appropriately formed. 2. A holding chuck is provided toward a substantially front end of an inner hole portion of a slider which is inserted into an inner hole of a tip portion provided at a front end of a shaft cylinder in a state where a tip portion projects from a front end of the tip portion. Further, the outer peripheral portion of the slider is engaged with the inner peripheral portion of the tip portion so as to advance and retreat at a predetermined interval, and the core holding force of the holding chuck is strongly set with respect to the engaging force of the slider. The mechanical pencil and the lead according to claim 1, which are formed of: