JPS6144858Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a plastic screw structure used in the barrel of a writing instrument.

A shaft holding an ink core shaft is usually screwed onto the top of the cylinder body of plastic writing instruments such as ballpoint pens and felt-tip pens, but the female threaded portion of this screwed portion is separated from the upper mold for plastic injection molding. In order to mold, it is necessary to provide a rotation mechanism for automatic extraction to rotate either the molded product or the mold, which increases the cost of the ancillary equipment for molding, takes time to extract the molded product, and makes mass production difficult. It had some flaws that made it unsuitable.

This invention is intended to eliminate the above-mentioned drawbacks, and its purpose is to form a spiral hole with a smooth inner periphery at the end of the internal hole of the outer cylinder body, and to By providing a small projecting piece for guiding the male screw groove from the surface and allowing the male screw to be freely screwed into the female screw hole, the function of the female screw part in the threaded part is maintained. The purpose is to simplify the structure and provide a screwing structure suitable for mass production.

This invention will be explained below with reference to the embodiments shown in the accompanying drawings.

1 is a plastic outer cylinder body of a ballpoint pen, pencil pen, felt-tip pen, etc. Inside the outer cylinder body 1 is a through hole 3 through which an ink core shaft 2 is inserted in the longitudinal direction.
is provided through it. Lower part 4 of outer cylinder body 1
is gradually tapered toward its tip.
The upper part of the internal through hole 3 of the outer cylinder body 1 is a screw hole 5 whose inner peripheral surface is a smooth surface, and this screw hole 5 has a male thread 6.
The outer diameter is the inner diameter that can be fitted. A small protrusion 9 for guiding the male screw groove 8 is protruded from the inner peripheral edge of the open end 7 of the screw hole 5.

That is, the small protruding piece 9 is a protruding piece that guides the male thread groove 8 provided within the gap between the crest a of the male thread 6 and the root b of the male thread 6. Also, male screw 6
The upper end 10 of the ink core shaft 2 is held at the lower part of the ink shaft. When the male screw 6 is completely screwed into the screw hole 5, the lower tip 11 of the ink core shaft 2
is arranged so as to protrude from the centering opening portion 12 of the outer cylinder main body 1.

In the drawing, the outer cylinder main body 1 is shown as an umbrella-shaped one, and an umbrella grip part 13 is provided on the upper part of the male screw 6.
However, the outer cylinder main body 1 and the male thread 6
The shape of is not limited to these.

The screw structure of the present invention can be used not only for writing instruments, but can be widely used as a screw structure for various articles in which the screw hole 5 and the male thread 6 do not require very strict screw precision. It is.

This idea eliminates the need for a rotary extraction device, which was conventionally required when extracting a molded product from a spiral hole, since the inner periphery of the spiral hole is a smooth surface, and at the same time, the molding time is significantly shortened. , products can be provided at low cost.

Moreover, the small protrusion protruding from the inner circumferential surface of the screw hole fits into the male screw groove and guides the male screw to slide smoothly as the male screw rotates, allowing the male screw to be attached to and removed from the screw hole. can be achieved freely.

For example, for products such as the barrel of a disposable ballpoint pen where threading accuracy is not an issue, the threading structure of the present invention is extremely effective in providing the product at a low price.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; FIG. 1 is a side view, FIG. 2 is a vertical sectional view, and FIG. 3 is a perspective view showing the male threaded portion removed from the outer cylinder body. FIG. 4 is a plan view of the outer cylinder main body, FIG. 5 is a perspective view showing the upper part of the outer cylinder main body cut away, and FIG. 6 is an enlarged sectional view of the main part. 1...Outer cylinder body, 2...Ink core shaft, 3...Through hole, 5...Spiral hole, 6...Male thread, 7...Open end, 8...Male thread groove, 9... Small protrusion.

Claims (1)

[Scope of utility model registration request] A screw hole 5 with a smooth inner periphery is formed at the end of the internal through hole 3 of the outer cylinder body 1, and a small protrusion for guiding the male thread groove 8 is formed from the inner peripheral surface of the open upper end of the screw hole 5. The lower part of the male screw part 6, which has a piece 9 protruding inward and can be freely screwed into the screw hole 5, is an ink core shaft 2 of a ballpoint pen, felt-tip pen, etc., and the lower end of the ink core shaft 2 is an outer cylinder. A plastic screw structure for a writing instrument, etc., characterized by protruding from the lower end of a main body 1.