JPS6259593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic shinai, and more particularly to a shinai that reduces the impact on an opponent's body when striking the opponent.

The present inventor has already disclosed in Japanese Unexamined Patent Publication No. 14872/1987 that a hard pipe core material such as a plastic core material with a Young's modulus of 10 ³ Kg/cm ² or more or a metal core material with a density of 2.0 g/cm ³ or more is used, We proposed a plastic shinai whose basic structure is a two-layered cylindrical body whose periphery is covered with plastic foam with a density of 1.0 g/cm ³ or less.

This plastic shinai not only hardly cracks or breaks like conventional bamboo shinai, but also has the advantage of being flexible and easy to adjust its weight and bending rigidity. This plastic shinai uses plastic foam around the hard pipe to alleviate the pain inflicted on the opponent's body when striking, but this is still insufficient.
Attempts to alleviate pain tended to increase the amount of plastic foam used, which tended to increase the weight of the shinai.

The purpose of the present invention is to improve such a plastic shinai, and to reduce the pain inflicted on the opponent's body when striking without impairing the strength and durability of the shinai or increasing the weight of the shinai. The purpose of the present invention is to provide a plastic shinai that can

It is configured so that two or more longitudinal notches are bored within about 1/2 of the total length from the tip of the hard pipe used as the core material.

The cut portion according to the present invention is one in which a hard pipe is cut in the length direction, resulting in a crack in the length direction. Moreover, this notch is formed in the tip portion, and its length is about 1/2 or less, preferably about 1/3 or less of the total length of the hard pipe. Although this cut portion significantly reduces the pain inflicted on the other person's body, if the cut portion is long and there are a large number of cut portions, there is a risk that the strength of the hard pipe may be impaired.
On the other hand, if it is shorter than about 1/6, the degree of pain relief is insufficient.

According to the research conducted by the present inventors, the bending increases as the number of notches increases, and two to four incisions are desirable. Further, it is desirable that the notches be provided at symmetrical positions; for example, even if there are two incisions, if they are provided biased to one side, a sufficient effect will not be obtained. In addition, in order to prevent cracks from forming at the tip of the notch on the hard pipe where the notch should not be made, the cracks may progress and the durability of the shinai will be reduced as a result. It is desirable to take measures to prevent this. For example, it is possible to prevent the propagation of cracks and to adjust the degree of bending by intermittently wrapping strong tape or thread around the cut portion, or by inserting a tight ring. Furthermore, if the tip of the notch is cut into a circular or semicircular shape, propagation of cracks can be prevented.

Furthermore, it is desirable to insert a cushioning material having some elasticity or cushioning effect into the notch. Inserting the cushioning material will act as a barrier to prevent the plastic foam raw material that is the outer skin material from penetrating into the hard pipe during manufacturing, and will also reduce the impact on the hard pipe when struck, increasing the durability of the shinai. will improve. Examples of the cushioning material include fiber aggregates, nonwoven fabrics, fabric pieces, rubber, elastomers, and plastic foams.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view, and the tip portion of the hard pipe is shown without being cut in section. FIG. 2 is a sectional view taken along the line ``-'', and FIG. Reference numeral 1 denotes a straight hard pipe with a diameter of 15 mm, and three notches 2 were bored at symmetrical positions up to about 1/3 of the way from the tip. An outer skin 3 made of plastic foam is provided around the hard pipe, forming a spindle shape in which the diameter gradually increases from the tip of the sword and decreases again toward the handle. Reference numeral 4 designates patterned grooves, which are provided on the outer periphery of the outer skin 3.If four grooves are provided, the appearance is divided into four parts, but if six grooves are provided, the appearance is shown divided into six parts. 5 is a thread, and a number 3 cotton thread is wrapped around it about 5 to 10 times and bonded. In this embodiment, two locations are provided, but the degree of bending can be adjusted depending on the number and degree of tightening. 6 is a tip cap, which is used to protect the tip of the sword, and is made of urethane rubber. A circular notch 7 as shown in FIG. 1 was provided at the tip of the notch 2 to prevent crack propagation.

In Fig. 4, two notches 2 are provided at symmetrical positions,
An example in which a cushioning material 8 is inserted into the cut portion is shown.
A spongy nonwoven fabric was used as the cushioning material. In this example, the outer skin material does not enter the hard pipe during molding.
It also has the effect of alleviating the impact of impact on the notch portion during impact and improving the durability of the hard pipe.

As described above, the present invention provides a bamboo sword in which a hard pipe is used as a core material and a plastic foam is used as an outer skin, and a bamboo sword is used in the length direction over a length within about 1/2 of the total length from the tip of the hard pipe. The notch at the tip solves the pain caused to the opponent's body when hitting, which cannot be solved by improving the outer shell alone, and at the same time improves the relationship between weight and flexibility. Adjust the balance in a well-balanced manner,
It is possible to provide a shinai that is superior to conventional shinai in terms of durability, ease of swinging, bending, pain, etc.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a substantially vertical cross-sectional view, FIG. 2 is a cross-sectional view along the line -- of FIG. 1, FIG. FIG. 7 is a cross-sectional view of another embodiment. In the drawing, 1 is a hard pipe, 2 is a notch, 3 is an outer skin, 4 is a pattern groove, 5 is a thread, 6 is a tip cap,
8 is a cushioning material.

Claims (1)

[Scope of Claims] 1. In a bamboo sword whose basic structure is a two-layered cylindrical body using a hard pipe as a core material and surrounding it with a plastic foam as an outer skin, the hard pipe has a length extending from the tip of the sword to the end of the sword. A plastic shinai that has two or more notches in the longitudinal direction over approximately 1/2 or less of its length. 2. The plastic shinai according to claim 1, wherein the notches are arranged at symmetrical positions in the cross section of the hard pipe. 3. In a bamboo sword whose basic structure is a two-layered cylindrical body using a hard pipe as a core material and surrounding it with a plastic foam as an outer skin, the hard pipe is within about 1/2 of the total length from the tip of the sword. A plastic shinai having two or more notches in the longitudinal direction extending along its length, and a cushioning material inserted into the notches.