JPS595588Y2 - Structure to prevent loosening of the base of the sharp pencil - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a structure for preventing the base of a mechanical pencil from loosening due to vibration or the like.

Since the cap of a conventional mechanical pencil is simply screwed onto a shaft joint, the cap is likely to loosen due to vibration or the like.

On the other hand, as shown in FIG. This is the difference between

Therefore, as described above, when the cap 11 loosens, the dimension C increases, and since the dimension b remains constant, the dimension of the lead feed amount a inevitably increases, resulting in disadvantages such as the risk of breaking the core. Ta.

In this invention, a compressed O-ring is interposed between the cap and the shaft coupling, and this repulsive force increases the frictional resistance between the cap and the shaft coupling, thereby preventing the cap from loosening due to vibrations, etc., thereby preventing the core from breaking. In addition, it is possible to shorten the threaded part of the cap and shaft joint to make the cap smaller, and it is possible to lower the machining accuracy of the threaded part and reduce costs. The purpose of the present invention is to provide a structure for preventing loosening of the base of a mechanical pencil.

An embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a shaft cylinder, and 2 is a shaft coupling.

The shaft coupling 2 has a screw 3 for screwing the cap on the outer periphery of the tip, and a fitting portion 5 on the base that is sequentially fitted into the hole 4 at the tip of the shaft tube and a locking portion that is locked on the inner surface of the tip of the shaft tube 1. The screw 3 is inserted from the inside into the hole 4 at the tip of the barrel, and the locking part 6 is inserted into the hole 4 at the tip of the barrel.
It is locked on the inner surface of the tip.

7 is a two-side chuck inserted into the shaft cylinder 1 from the tip side of the hole of the shaft coupling 2, 8 is a core case fixed to the base of the two-side chuck 7, and 9 is between the shaft joint 2 and the core case 8. a spring that is interposed and urges the locking part 6 of the shaft coupling 2 to the inner surface of the tip of the shaft cylinder 1;
10 is a fastener 11 fitted on the outer periphery of the tip of the two-side chuck 7, which has a screw 12 inside, and a base screwed onto the shaft coupling 2; 13 is a holding chuck provided inside the base 11; be.

In the mechanical pencil of the present invention, a groove 14 is formed between the screw 3 and the fitting part 5 in the shaft joint 2, and the base 1
An inclined portion 15 is formed on the inner periphery of the proximal end portion of 1.

An O-ring 16 made of a soft elastic material is interposed in a compressed state between the groove 14 of the shaft coupling 2 and the inclined portion 15 on the inner periphery of the base end of the base 11.

This O-ring 16 has an outer diameter that is approximately the same as or smaller than the diameter of the hole 4 at the tip of the shaft cylinder 1, and the screw 1 of the base 11.
The diameter of shaft joint 2 is larger than that of shaft joint 2 during installation.
An O-ring 16 is fitted into the groove 14 in advance, and the shaft coupling 2 and the O-ring 16 are inserted into the hole 4 of the shaft cylinder 1.

As is clear from the above, according to the present invention, an O-ring is interposed between the shaft joint and the shaft joint in a compressed state in the front and rear and radial directions, and this repulsive force increases the frictional resistance between the shaft joint and the shaft joint. Therefore, it is possible to prevent the cap from loosening due to vibrations, etc.

Therefore, there are the following advantages.

1. Breakage of the core caused by loosening of the cap while carrying can be prevented.

2. Breakage of the lead caused by loosening of the cap during writing can be prevented.

3. There is no change in the amount of lead out during writing, and breakage of the lead can be prevented.

4. Since the threads of the shaft joint and the cap can be shortened, the cap can be made smaller, and the machining accuracy of the screws of the shaft joint and the cap can be lowered, so it can be provided at a low cost.

Since the outside diameter of the 50 ring is set to be approximately the same as or smaller than the inside diameter of the hole at the tip of the barrel, and larger than the thread diameter of the cap screw, installation of the O-ring to the shaft coupling is optional during the assembly process of the mechanical pencil. You can do the following things.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts of a mechanical pencil implementing the cap loosening prevention structure of the present invention. DESCRIPTION OF SYMBOLS 1... Shaft cylinder, 2... Shaft joint, 7... Two side chuck, 8... Core case, 10... Fastener, 11... Mouthpiece, 13... Holding chuck, 16 ...O-ring.

Claims (1)

[Scope of utility model registration request] A shaft coupling 2 having a thread at the tip is inserted into a hole at the tip of the barrel from the inside of the barrel 1, and the base of the shaft coupling 2 is locked to the inner surface of the tip of the barrel. In a mechanical pencil in which a screw on the inner periphery is screwed, there is a hole at the tip of the barrel whose outer diameter is between the groove 14 on the outer periphery of the terminal end of the screw in the shaft coupling 2 and the sloped part on the inner periphery of the base end of the base. A cap loosening prevention structure for a mechanical pencil comprising an O-ring which is approximately the same as or smaller than the inner diameter of the cap and which is larger than the thread diameter of the cap screw, interposed in a compressed state in the front and rear and radial directions.