JPS5832959Y2 - Lead protection device for sharp lead pencils with fine leads - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a lead protection device for a mechanical pencil with a fine lead, which comprises a lead passage tube and a lead holder.

Conventionally, mechanical pencils have been designed to prevent the lead from falling out of the tip of the main body due to its own weight when the lead holding and sending groove of the chuck moves forward to release the lead, and to prevent the lead from breaking. To prevent this, a core protection device consisting of a core pushing tube and a core holder is adopted.

As shown in Fig. 1, a conventional lead protection device has a lead insertion tube 1 formed in a lead-passing tube 1 that serves as a tip tube that is non-slidably attached to the tip of a mechanical pencil A equipped with a lead feed device B. A cylindrical core holding member 3 made of an elastic material such as rubber and having a hole slightly smaller than the outer diameter of the core is attached to the inner end 2' of the hole 2 by means such as fitting, or a second As shown in the figure, an annular protrusion is formed on the inner circumferential surface of the core insertion hole 2 by squeezing the outer periphery of the tip of a core insertion tube 1 made of a metal tube such as a stainless steel pipe that is slidably installed in the tip of the main body. 3 in which a core holding portion is formed is well known.

However, in the case of the one in Figure 1, the outer diameter of the core is 0.70.5.
Alternatively, for fine cores such as 0.3 am, the parts are very small, making them difficult to mount and having poor workability.

In addition, when it comes to such thin cores, when the tip becomes thick, a blind spot is created and it is difficult to write.In fact, the outer diameter of the core push tube for thin cores is only about 0.7 tnm to 1.3 tnm. For reasons such as the impossibility of attaching the lead holding member to the distal end, the lead holding member 3 must be attached to the inner end 2'.

As a result, the distance between the tip of the core pushing tube and the core holder inevitably becomes longer, and the lead that has become worn out and shortened and is no longer held in the chuck will pass through the holder when a new core is delivered. Since it is not held at the tip of the insertion tube, it falls off, resulting in a large number of so-called lost cores, which is uneconomical.

In addition, in the case of the one shown in Fig. 2, the core holding part can be formed at the tip of the core passing tube, so the loss of core can be reduced, but since it is made of metal, the outside of the core inserted It cannot absorb variations in diameter, and if the core is thin, it cannot be held and falls off under its own weight.

Otherwise, if it is too thick, it will collide with the annular protrusion, making it impossible to send out, leading to the core breaking at the core and causing clogging, etc., and because the core requires high precision, it has not been put into practical use yet. I am not getting what I am satisfied with.

The present invention solves these drawbacks and provides a mechanical pencil lead protection device that is simple in structure, low in cost, and almost eliminates lead loss.

Examples will be described below.

FIG. 3 shows an embodiment of a so-called sliding mechanical pencil that is slidably attached to the tip of the main body.

In Figure 1, A is the main body of the mechanical pencil, and barrel 1
, a tip tube 2 connected to the tip of a shaft tube 1 by means of fitting or the like.

A lead holding and delivering device B consisting of a chuck 3, a chuck ring 4, a spring 5, and a lead storage cylinder 6 for tightening the knock rod is installed inside the shaft cylinder 1, and a lead protection device C is inserted into the tip cylinder 2. It is attached so as to be slidably protruded from or retracted from the hole 7.

The lead protection device C is made of a metal pipe made of stainless steel or the like with an outer diameter of about 0.7 VTM to 1.3 mm, which is the same as that of ordinary fine lead mechanical pencils, so as not to create blind spots and make it difficult to write. It has a tailstock passage tube 8.

For example, when a core having an outer diameter of 0.5 am is used, the core stock tube 8 is formed so that the outer diameter of the core stock pipe 8 is 1.3 mm and the inner diameter is 1 mm.

The actual outer diameter of the normal 0.5 am core here is 0.5
It is slightly smaller than rnm, and according to JIS, it is 0.55 to 0.
．． It is specified as 58mm.

A thin film 10 made of an elastic material such as rubber plastic is integrally laminated on the entire circumference of the inner surface 9 of the tailstock tube 8, either directly or via an adhesive. The core holding portion 11 is formed to have an inner thickness smaller than the outer diameter of the core.

From the middle part to the distal end 8'', the inner diameter is thicker than the outer diameter of the core so that the core can be easily inserted therethrough.

Further, a core guiding portion 13 having a funnel-shaped core guiding hole 12 connected to the thin film 10 and a flange portion 14 for preventing slipping out are integrally formed on the distal end portion 8'' so as to be fitted onto the outside thereof.

The flange portion 14 may be omitted since it functions as a retainer if the outer diameter of the core guiding portion 13 is made large.

The thickness of the thin film 10 is, for example, when using a core of 0.5 nm, the core holding part 11 is about 0.226 mm, and the non-holding part from the middle part to the end part 8'' is about 0.20 ur.
It is formed to have a thickness of about n.

The following is an example of the manufacturing method of the core protection device C:
First, an adhesive is applied to the inner surface 9 of the tailstock tube 8 by, for example, dipping the corestock tube 8 in an adhesive solution.

Alternatively, as shown in Fig. 6 without coating, insert the core stocking tube 8 into the mold X, then set the mold Y, press-fill the molten synthetic resin or rubber through the gate G, and then cool it. A core protection device C is obtained by integrally laminating the elastic thin film 10 on the inner surface 9 of the core stock tube 8.

Incidentally, the thin film 10 does not necessarily have to be formed all around the circumference as in the embodiment, and may be formed only on a part of the inner surface 9 of the cored passage tube 8 in the cross section as shown in FIG.

At this time, the core holding portion 111 is formed to have a thickness such that the distance d between the opposing inner surface and the surface of the thin film 10 is slightly smaller than the outer diameter of the core to be inserted.

Although not shown in the drawings, it is of course possible to form a core holder by laminating a thin film 10 on only the inner circumferential surface of the tip end of the core stock tube 8 so that its inner diameter is slightly smaller than the outer diameter of the core. be.

Further, the core holding portion may be formed by laminating thin films 10 of uniform thickness not only on one part of the inner surface of the core pushing tube 8 but also over the entire length thereof, the inner diameter of which is slightly smaller than the outer diameter of the core. If it is difficult to feed out the lead due to the frictional resistance with the lead, a plurality of inward protrusions are formed on the thin film 10 in the cross section as shown in FIG. Also good.

Furthermore, the present invention is non-slidably attached to the tip of the user as a tip tube.

It can also be used as a lead protection device consisting of a lead-through tube formed in a tapered shape so that it does not become a blind spot and make it difficult to write, and an appropriate structure can be adopted.

The present invention is constructed as described above, and since the lead holding part is integrally formed by laminating a thin film of elastic material on the inner surface of the lead insertion tube, the tip becomes thicker, creating a blind spot and making it difficult to write. In addition, it has become possible to shorten and almost eliminate the loss core.

In addition, since the thin film can be easily formed, the workability is good and the accuracy of the lead protection device is greatly improved, and there is no fear that the lead holding member will fall off during use as in the conventional case.

Also, in the case of a lead protection device used in a sliding type mechanical pencil, it is possible to integrally form a flange portion for preventing the device from slipping out, resulting in low cost.

Furthermore, since the distance between the lead holding and feeding mechanism and the lead protection device can be shortened, there is an effect that breakage of the lead is reduced.

[Brief explanation of drawings]

1 and 2 are partially omitted vertical sectional views of a mechanical pencil equipped with a conventional lead protection device; FIG. 3 are vertical sectional views of a mechanical pencil equipped with a lead protection device according to an embodiment of the present invention; Figure 4, enlarged vertical cross-sectional view of the core protection capacity in Figure 3, Figure 5a
-a cross-sectional view, FIG. 6, an explanatory view showing the manufacturing state of the embodiment of the present invention, FIGS. 7 and 8, cross-sectional views of the core protection device of other embodiments of the present invention. A-Mechanical pencil body, C-Lead protector, 8.10
8,208-core insertion tube, 9,109°209-inner surface, 1
0,110,210 - elastic thin film, 11.111,211
- Core holder.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In a lead protection device for a mechanical pencil for fine lead, which consists of a lead pushing tube and a lead holder, which are slidably or non-slidably attached to the tip of the main body, A lead protection device for a mechanical pencil with a fine lead, characterized in that a lead holding part is formed by integrally laminating an elastic thin layer made of rubber or the like on the inner surface of a push-through tube.A tip part of the inner surface of a push-through tube. A lead protection device 3 for a mechanical pencil for fine lead according to Claim 1 of the Utility Model Registration Claim in which a lead holder is formed at the tip end of the inner surface of the lead-through tube, and a lead holder is formed at the end end. A lead protection device for a mechanical pencil for fine lead according to claim 1, which is a utility model, and includes a lead guide part in which a funnel-shaped lead guide hole is formed through a non-retaining part.