JPS5839915Y2 - Main body structure of Knotsuku style pencil - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a main body structure of a knock-type mechanical pencil that has a small number of parts and is easy to assemble.

Generally, in a knock-type mechanical pencil, when writing, the chuck is forced backwards, and the rear end of the tightening ring fitted in the chuck comes into contact with the gripping step inside the barrel, tightening the chuck head. The lead is gripped, and when knocking, the front end of the tightening ring comes into contact with the release step in the nib and separates from the chuck head, causing the chuck head to expand and release the pencil lead.

Therefore, the main body structure requires a tightening ring mounting portion which is an annular large-diameter space having a release step and a gripping step at the front and rear.

However, if the tightening ring attachment part is an integral structure, it is not possible to attach a tightening ring with a diameter larger than the smaller diameter part of the front and rear step sections during assembly. A release step is provided at the tip, and the barrel and tip are separated into three parts. After installing the chuck and the tightening ring on the large diameter part of the tip inside the barrel, the large diameter part of the tip is removed. A tightening ring was attached to the large diameter part of the shaft cylinder using a screw.

Therefore, the number of parts increases, and it is necessary to machine screws for each of the tip and the barrel, and it also requires time and effort to screw the tip to the barrel during assembly.

The present invention was developed based on these circumstances, and it forms a tightening ring attachment part in the barrel, making the tip and the barrel an integral structure, and the tightening ring attachment part of the barrel. An opening large enough to allow the chuck fitted with a tightening ring to be inserted into the shaft cylinder is provided on the side of the part containing the clamp, and the tightening ring and chuck are inserted through this opening during assembly, and a pencil is attached to the rear end of the chuck. By press-fitting the lead housing cylinder, it is possible to obtain a mechanical pencil that has fewer parts and is easy to assemble.

Hereinafter, the structure of the main body of the knock-type mechanical pencil according to this invention will be explained in detail according to the plan view.

The chuck 1 is a cylindrical body into which a pencil lead 2 is inserted, and its tip is split, and the chuck head 3
has a tapered surface for light spreading on its outer periphery, and is urged to spread in the radial direction by the cut groove.

The rear end of the chuck 1 is press-fitted and fixed into the pencil lead storage tube 4, and a spring body 5 is provided between the pencil lead storage tube 4 and the shaft tube 7 in a direction that urges the shaft tube 7 backward. Therefore, the chuck 1 is also biased rearward.

The tightening ring 6 is a ring having an inner hole smaller in diameter than the maximum outer diameter of the chuck head 3, and is fitted into the chuck 1 from the rear end and attached to the tightening ring mounting portion 9.

When writing, the chuck 1 is urged backward as shown in FIG. 2 and fix it.

When knocking, the chuck 1 resists the urging force of the spring body 5.
moves forward, and the front end of the tightening ring 6, which initially moved forward together with the chuck 1, comes into contact with the release step 10 and stops.Since only the chuck 1 moves forward, the chuck head 3 expands in the radial direction. The pencil lead 2 is released from the grip.

Here, the shaft tube 7 and the tip 8 are integrally injection molded from synthetic resin, and as described above, inside the shaft tube 7, the front step is the release step 10, and the rear step is the release step 10. is the gripping step part 1
A tightening ring mounting portion 9 having an annular large diameter space is formed.

A soft elastic member 13 such as rubber is fitted inside the tip opening 8 and contacts the pencil lead 2 to prevent it from falling when the pencil lead 2 is released from the chuck 1. A guide tube 14 for protecting the pencil lead 2 is inserted and fixed therein.

An opening 12 is provided in the side surface of the portion of the shaft tube 7 that includes the tightening ring mounting portion 9.

During assembly, the chuck 1 fitted with the tightening ring 6 is inserted through the opening 12 and installed into the shaft cylinder 7.
The width of this opening 12 is not smaller than the outer diameter of the tightening ring 6, and since the required size in mud varies depending on the length and flexibility of the chuck 1, the inner diameter of the shaft cylinder 7, etc., it is not decided on one type. However, the key is to make the size necessary for the chuck 1 to be inserted.

In any case, it is desirable to make the opening 12 the minimum necessary size in terms of the rigidity of the shaft tube 7.

Note that in order to form this opening 12, a small splitter mold is used when injection molding the shaft cylinder 7, and the molding is performed at the same time.
At this time, if it is convenient to make the mold symmetrical in terms of the mold structure, two openings 12 may be provided facing each other.

When assembling the knock-type mechanical pencil according to the present invention, the spring body 5 and pencil lead housing tube 4 are inserted from the rear end opening of the square barrel tube 7, and then the tightening ring 6 is fitted from the rear end. The chuck 1 temporarily fixed to the chuck head 3 is inserted into the shaft cylinder 7 through the opening 12 with the rear end facing forward.

At this time, since an opening 12 is provided on the side surface including the tightening ring mounting portion 9, when the tightening ring 6 is inserted, it is mounted on the tightening ring mounting portion 9.

Then, the pencil lead housing cylinder 4 may be pressed and fit into the rear end of the chuck 1 within the shaft cylinder 7.

As described above, according to the present invention, the tip and barrel, which were conventionally separated and made into one part, can be integrated into one piece, and the processing and joining process for joining the tip and barrel can be simplified. There are advantages to not needing it.

Particularly in the case of popular mechanical pencils in which these parts are injection molded from synthetic resin, the effect is remarkable because the injection molding process, including the formation of the aperture, can be carried out at the same time.

In addition, the opening allows the internal structure to be directly viewed, giving the viewer an impression of a highly functional product.Furthermore, the chuck can be used to hold the pencil lead while dispensing it. It also has a secondary effect, such as being able to discharge the generated pencil lead powder through this opening.

[Brief explanation of drawings]

Figure 1 is a sectional view of an embodiment of the present invention, Figure 2 is Figure 1 II
It is a sectional view taken along the line -II. 1...Chuck, 4...Pencil lead storage tube, 6...Tightening tongue, 7...Shaft tube, 8
...Tip, 9...Tightening rig attachment part,
12...Opening.

Claims (1)

[Scope of utility model registration request] A shaft cylinder having a tightening ring mounting portion formed therein, which is an annular large-diameter space having stepped portions at the front and rear, and a tip at the tip thereof are integrally constituted, and the tightening ring mounting portion of the shaft cylinder is integrally formed. 1. A main body structure of a knock-type mechanical pencil, characterized in that an opening is provided on the side surface of the part including the opening having a size such that a chuck fitted with a tightening knock can be inserted into the shaft cylinder.