漁網用コードの耐摩耗試験

Abstract

Fibers for fishing industry have been supplied exclusively with natural substarces such as flax, cotton or silk years back. However, of late, with such a remarkable development in the fabrication of man-made fibers, synthetics have gained their popularity in the industry and are challenging with success to the more conventional types of fiber.Among the various properties any maritime fiber is supposed to have, resistance to abrasion as well as strength is of vital importance.This reporter would like to give some accounts of a newer type of abrasion testing machine for fishing-net cords, which is featured with an elimination of shortcoming involved in an usual measurement method or in a conventional testor. This model yielded very satisfactory results.Of a number of factors that every testor of this nature must necessarily be possessed of, the following points were received a special attention in our effort to build up this testor.1. An abradant is open to unreproducible change in its surface condition with abrasion. Therefore, in its stead, such a mechanism is used as to permit abrasion between two ends of cords possible.2. To that extent that frictional strength created by rubbing process is added to original tensile strength by dead-weight, real breaking tensile strength is likely to be all the more bigger. Yet, in reality, tension is valued by the amount of dead-weight charged, with a resulting measuremeet errors being aggravated in an area where dead-weight bears only a minor significance. This structure is featured with a mechanism by which friction force at abrading process will not be added, per se, to the strings tested.3. Abrasion will register a different value according to the angle to the string abraded. This mechanism is designed to measure up diagonal abrasion to the string.4. Generally speaking, abrasion takes place with flexings, so this mechanism is built by taking that fact into fullest account.5. With our mechanism, it is as easy to measure abrasion under water as that in air.6. In order to facilitate simultaneous measurement the mechanism is made small in size, yet is able to handle so many of materials for test purpose.Outline of the Mechanism:Ends of fibers are crossed, as are depicted on the Figure, on freely rotatable four (4) round poles (16mm∅) that will reciprocate up and down (51r.p.m) with their relative position remaining unchanged. Then set the round poles in motion upward and downward, keeping the strings stretched bs plummets (weighing 0.5 to 2kg.), with pulleys inbetween. With a passage of time, the fibers undergo wear and tear, followed by final breaking. The larger the dead-weight, the smaller are the reciprocating rounds before the break. The functional relationship between the rounds and dead-weight is, as has been found, that of logarithmic linearity with in a certain limit. A series of tests conducted both in water and in air revealed that resistance to abrasion and tensile strength did not go hand by hand. Tension of Teviron and Saran, in particular, is the same either in water or in air. Resistance to abrasion in air is, however, appreciably weaker as compared with the value in water. This may be accounted for by the fact that these synthetics have essentially very low thermo-softening points and that abrasive process otherwise accelerated by rubbing heat is seemingly checked by cooling-off effect of water. Nylon is known to have higher resistance to abrasion than any other fibers, and the blending of the former with the latter to cement for further resistance to abrasion will exert a considerably favorable effect.