JPS5852151Y2 - Shaft coupling of Knock type shear pencil - Google Patents

Description

[Detailed description of the invention] The present invention relates to a shaft coupling for a knock-type mechanical pencil, which makes it easy to confirm that the shaft coupling is positioned in the correct position, and also allows the shaft and cap to be connected in different positions. The object of the present invention is to obtain a shaft joint for a mechanical pencil that has low resistance and is easy to fit in the correct position even when the mechanical pencil is assembled.

Conventionally, in order to correctly position the internal mechanism of a knock-type mechanical pencil on the shaft, the shaft joint was formed by cutting a metal material such as brass with an irregular cross section, and the corresponding inner cylinder was fixed inside the shaft. Was.

In order to streamline the manufacturing process of mechanical pencils having such a structure, in recent years, in the case of aluminum shafts, a rotation stopper has been integrally formed within the shaft.

However, in the case of shafts made of brass or stainless steel, such integral molding is difficult, so as shown in Figure 4, the end surface of the outer shaft of the shaft joint is formed into an irregular shape, so a material with an irregular cross section is used. The shaft joint is machined and a corresponding hole is formed at the tip of the shaft.

However, in this case, it is very difficult to check whether the internal mechanism of the mechanical pencil is correctly positioned on the shaft coupling, and the cap can be tightened even if it is in the wrong position, and the cap may become loose. This method has various drawbacks, such as the position at which the fastener comes off changes, and a large amount of lead is paid out with one knock, which can lead to breakage of the lead.

The present invention provides a shaft joint for a knock-type mechanical pencil that eliminates the above-mentioned drawbacks by having the configuration described in the claims of the above-mentioned utility model registration.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention is demonstrated based on the Example shown in drawing.

1 and 2 show an embodiment of the present invention, in which a mechanical pencil 1 has a lead case 3 housed inside a shaft 2, and a spring 4 is connected to the front of the lead case 3. A hollow shaft joint 5 is arranged.

A chuck 6 connected to the core case 3 and a chuck fastener 7 disposed around the outer periphery of the chuck 6 are provided inside the shaft joint 5.

The shaft joint 5 has an outer shaft portion 8 as a stopper portion formed at the rear end thereof, and the outer shaft portion 8 has a stepped portion 9 and is formed to have a larger diameter than other portions.

In addition, rotation prevention portions 10 are formed protruding forward from the outer circumferential wall of the shaft joint at several locations (in this embodiment, two locations) on the front end surface of the outer shaft portion 8, that is, the stepped portion 9, and the rotation prevention portions The tip end of 10 is formed into a tapered chamfered part 11.

Further, a threaded portion 12 is formed with a predetermined width from the tip of the rotation prevention portion 10 of the shaft coupling 5, and the threaded portion 12 is screwed into a threaded portion 14 formed at the rear end of the base 13. It is something.

The shaft joint 5 is configured to engage with the tip flange portion 15 of the shaft 2 at a portion of the stepped portion 9 where the rotation prevention portion 10 is not formed, so that it will not move forward any further. , and the base 13 is integrally attached to the shaft joint 5 by threading the threaded parts 12 and 14, so that the shaft 2. The shaft joint 5 and the base 13 are firmly connected.

Concave grooves 16 and 17 are provided at the rear end of the flange portion 15 of the shaft 2 and the base 13 at positions corresponding to the rotation prevention portion 10.
is formed, and the shaft 2. When the shaft coupling 5 and the base 13 are connected together, the rotation preventing portion 10 is fitted into the grooves 16 and 17.

In the shaft coupling of the present invention having the above configuration, the internal mechanism including the core case 3 is held in the correct position by fitting the concave groove 16° 17 of the shaft 2 and the base 13 with the rotation prevention part 10 of the shaft coupling 5. Since the base 13 cannot be sufficiently screwed onto the shaft coupling 5 at a different position, the correct position can be confirmed at a glance.

Furthermore, even if the internal mechanism is in a different position and the base 13 is fitted to the shaft coupling 5, the shape of the chamfered part 11 at the tip of the rotation prevention part 10 will cause the edge of the flange part 15 of the shaft 2 to Since the resistance against the rear end edge of the base 13 is small, it operates so that the shaft joint can be easily rotated to the correct position and accommodated.

Furthermore, as shown in FIG. 3, this effect is further enhanced by providing four grooves.

It is preferable that the shaft joint be integrally molded with self-lubricating resin, and even if the internal mechanisms are in different positions and the cap and shaft joint are screwed together, they will still rotate to the correct position even if there is little resistance. Benefits can be obtained.

Furthermore, by forming the resin, the elasticity of the resin prevents the cap from loosening.

The present invention provides a shaft joint having the above-mentioned configuration 2 function with a rotation prevention part that fits into a groove formed in the shaft and the base, and also by forming a chamfered part at the tip of the rotation prevention part. , the internal mechanism of the mechanical pencil can be easily positioned in the correct position relative to the shaft joint, and the shaft joint and cap can be screwed together, and it is possible to prevent a large amount of lead from being drawn out with a single knock. This has many effects, such as preventing the cap from loosening.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a shaft coupling according to an embodiment of the present invention, Fig. 2 is a perspective view of the same as above, Fig. 3 is a view showing the tip of the shaft, and Fig. 4 is a conventional shaft coupling and its corresponding hole. It is a figure which shows the shape of a part. 5... Shaft coupling, 8... Outer shaft portion, 10.
...Rotation prevention part, 11... Chamfered part, 1
3...cap, 2...shaft.

Claims (1)

[Scope of utility model registration request] A shaft joint for a knock-type mechanical pencil that has a part of a stopper and a rotation prevention part, into which an internal mechanism in which a chuck, a fastener, a spring, a lead case, etc. are slidably assembled is inserted, and a base is integrally attached. A shaft joint for a knock-type mechanical pencil, characterized in that the rotation prevention portion projects in the axial direction from the outer shaft end surface of the shaft joint, and a chamfered portion is provided at the front end of the rotation prevention portion.