JPS591834Y2 - Structure to prevent the cap from loosening in double-knock mechanical pencils - Google Patents

Description

[Detailed description of the invention] This invention uses a knock to lock the internal mechanism consisting of the chuck, fastener, lead tank, etc. in the forward position when writing, and to the retracted position where writing is not possible when not writing. In so-called double-knock mechanical pencils that are equipped with a locking forward/backward mechanism, this mechanism prevents the cap screwed onto the tip of the case outside the internal mechanism from loosening, thereby constantly keeping the amount of lead drawn out constant. This prevents the core from breaking due to an abnormality in the amount of feed.

For knock-type mechanical pencils, the amount of lead delivered per knock is determined by the amount of movement of the chuck's clamp, and the amount of movement of the clamp is determined by the distance between the clamp and the locking step on the inside of the mouthpiece. It is determined by (see Figure 3).

However, when the cap loosens, the distance between the fastener and the locking step on the inner surface of the cap increases, and as a result, the amount of lead drawn out per knock becomes abnormally large, leading to lead breakage. .

In particular, in the case of a double-knock type mechanical pencil, the forward and backward stroke of the internal mechanism by the forward and backward mechanism is significantly larger than the forward and backward stroke of the chuck for feeding out the lead. The cap loosens more easily than a normal knock-type mechanical pencil due to the shock, and if the cap loosens, not only will the lead be drawn out abnormally, but the cap may hit the tip of the tip, making it impossible to move the internal mechanism forward.

Moreover, double-knock type mechanical pencils have the disadvantage that the internal mechanism is covered by the tip shaft and cap, so even if the cap loosens, it cannot be seen from the outside, so it is easy to overlook the loosening of the cap. Even if you find that the cap is loose, in order to retighten it, you must remove the cap from the tip shaft, take out the internal mechanism, and retighten the cap. It requires time and effort to put the cap in the shaft and attach the cap to the tip shaft.

Therefore, there is a need for an effective measure to prevent the cap of the double-knock mechanical pencil from loosening.

This invention uses a knock type mechanism to lock the internal mechanism consisting of the chuck, fastener, lead tank, etc. in the forward position when writing, and locks it in the retracted position where writing is not possible when not writing. In the mechanical pencil equipped with the mechanical pencil, an annular groove is formed at the end of the screw of the outer case of the internal mechanism, an O-ring is fitted into the annular groove, a cap is screwed onto the screw of the outer case, and the O-ring is inserted into the cap. The repulsive force of the O-ring, which is compressed between the inner surface of the proximal end and the annular groove, increases the frictional resistance between the cap and the outer case to prevent the cap from loosening due to vibration.

Embodiments of the present invention will be described below with reference to the drawings.

In Figures 1 to 3, numeral 1 is the front shaft, and 2 is the front shaft 1.
A cap 3 is screwed onto the outer case of the internal mechanism inserted into the tip shaft 1, and a cap 5 is screwed onto the screw 4 at the tip.

The internal mechanism consists of the 3-split chuck 6, the fastener 7 of the 3-split chuck 6, the relay pipe 8, the core tank 9, and the knock cover 10 fitted to the rear end of the core tank 9. The relay pipe 8 is connected to the rear end of the chuck 6 with the fastener 7 attached to the outer case 3.
The fastener 7 is inserted into the through hole 11 of the outer case 3 so as to come into contact with the tip of the outer case 3, and the core tank 9 is connected to the end of the relay pipe 8 that goes out from the outer case 3.

An annular groove 12 is cut into the terminal end of the screw 4 provided at the tip of the outer case 3, and an O-ring 13 made of rubber or other soft elastic material is fitted into the annular groove 12.

The outer diameter of the O-ring 13 is larger than the outer diameter of the screw 4 of the outer case 3, and larger than the diameter of the inner circumferential surface of the proximal end of the cap 5 that is screwed onto the outer case and covers the O-ring 13. Therefore, when the cap 5 is screwed onto the outer case 3, the O-ring 13 is compressed between the inner peripheral surface of the proximal end of the cap 5 and the annular groove 12, and its repulsive force causes the O-ring 13 to be compressed. 5 and outer case 3
This increases the frictional resistance between the base and the cap 5, thereby preventing the cap 5 from loosening.

Therefore, the distance between the fastener 7 and the locking step 14 on the inner surface of the mouthpiece 5 is constant, and the amount of feed of the core 15 is constant.

Reference numeral 16 denotes a projecting edge provided at the rear end of the outer case 3;
6 and the step 17 on the inner surface of the tip shaft 1 is a large spring S.
1 is compressed and constantly presses the outer case 3 backward.

S2 is a core payout spring wrapped around the relay pipe 8 protruding from the outer case 3, and when the knock cover 10 is slightly knocked, the relay pipe 8 and the 3-split chuck 6 are moved without compressing the large spring S1. can move forward.

The illustrated example shows a large spring S and a plurality of protrusions 1 provided on the inner peripheral surface of the cap 2 as the forward and backward mechanism of the internal mechanism.
B and a rotating ring 20 having a protrusion 19 formed on its outer circumferential surface that engages with the tip of the protrusion 18 on the inner circumferential surface of the cap 2, or disengages from the engagement and fits loosely into the gap of the protrusion 18. A mechanism is adopted in which the ring 21 is slid by pressing against the elasticity of the S.
This is an improved version of the mechanism described in No. 1 and is well known, so detailed explanation thereof will be omitted.

Of course, when implementing the present invention, there is no problem in adopting a forward/backward mechanism other than the forward/backward mechanism described above and shown in the drawings.

The configuration of the present invention is as described above, and according to the present invention, a groove is formed at the terminal end of the screw of the outer case, and the O-ring is placed in a compressed state between the groove and the inner periphery of the base end of the base. Since this repulsive force increases the frictional resistance between the cap and the outer case, it is possible to prevent the cap from loosening due to vibration or the like.

Therefore, there are the following advantages. (1) Since the cap does not easily loosen, the lead is less likely to break accidentally while writing.

(2) Since the cap does not easily come loose, accidents in which the amount of lead drawn out becomes abnormally large can be prevented to a minimum. (3) Knocking defects due to loosening of the cap can be prevented.

(4) Even if the cap is tightened with a relatively weak force, it will not loosen easily.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention. Figure 1 is a cross-sectional view of a double-knock mechanical pencil with a structure to prevent loosening of the cap, and Figure 2 is a partially cutaway view of the internal structure. The front view and FIG. 3 are enlarged sectional views of the main parts. 3... Outer case, 4... Screw, 5... Base, 6...
・Three-split chuck, 7... Fastener, 9... Core tank, 12... Annular groove, 13... 0 ring.

Claims (1)

[Scope of utility model registration request] Sharps equipped with a forward and backward mechanism that uses a knock to lock the internal mechanism, which is removed from the chuck, fastener, lead tank, etc., in the forward position when writing, and in the retracted position where writing is not possible when not writing. In the pencil, an annular groove is formed at the end of the screw of the outer case of the internal mechanism, and an OIJ ring made of rubber or other soft elastic material is fitted into the annular groove,
A structure for preventing loosening of the cap of a double-knock mechanical pencil, characterized in that the cap is screwed onto a screw of an outer case, and the O-ring is compressed between the inner surface of the base end of the cap and an annular groove.