JPS6044627A - Coiled spring - Google Patents

Abstract

PURPOSE:To improve load-resisting performance by disposing a unidirectional carbon fiber/epoxy resin prepreg layer having a large shearing strength at least near the outer surface. CONSTITUTION:A unidirectional carbon fiber/epoxy resin prepreg layer having a large shearing strength of more than 10kg/mm.<2> is arranged and laminated + or -35- + or -55 deg. in order to increase torsion resistance, and is wound round a suitable core material such as a metal wire, plastic wire or the like. At this time, the prepreg is wound into a cylinder in such a manner that the prepreg winding end is not positioned inside the coil. The thus wound prepreg is heated and hardened to obtain a coiled spring.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coil spring whose main material is CFRP (abbreviation for reverse fiber reinforced resin).

CFRP coil springs are lightweight yet highly durable, so they have long attracted attention as springs for vehicles. However, the CFRP coil spring that was actually prototyped did not show the expected load-bearing performance and its light storm reduction effect was small, so it has not yet been put into practical use.The reason for this is the shearing of the material. Low strength, V during molding
This is because defects such as disordered fiber orientation, voids, and cracks occur.

The inventors of the present invention have arrived at the present invention as a result of intensive cross-sectional research to eliminate the drawbacks of conventional CFRP coil springs.

That is, the gist of the present invention is to provide a carbon fiber reinforced resin coil in which a unidirectional carbon fiber/epoxy packing prepreg layer having an interlayer shear strength of 10 kg/- or more is disposed at least near the outer surface. More specifically, the prepreg winding end of the outermost layer is arranged without being located inside the coil, and the interlayer shear strength is l10I.
The prepregs are laminated with winding ends of c/- or more at ±350 to ±SS0, wound around a core material, and then formed into a coil shape to form a coil spring.

The present invention will be explained more specifically as follows.

The coil spring material of the present invention is a unidirectional carbon fiber/epoxy layer prepreg that is KJ-formed to form elongated cylindrical objects such as fishing rods and golf shafts.

This material has the most efficient shape for winding operations and is suitable as the material of the present invention.

However, in the case of fishing rods and golf shafts, the main direction of external force acts to bend the object, whereas in the coil spring of the present invention, the direction of the main external force acts to twist the object around the center of the spring wire, so the fibers are arranged themselves. is different.

That is, it is necessary to maintain the angle of the fibers with respect to the center line of the spring wire within ±330° to ±33° to provide maximum resistance to twisting. However, since it is impossible to suddenly stack them in a coil shape, the blob legs are arranged and stacked at a predetermined angle in advance, and then a suitable core material such as Kinpo wire, etc. is used.
Wrap it around a wire rod with a diameter smaller than the desired coil spring wire diameter using plastic wire, etc. The core material may be a prepreg material.

If a core material is formed by winding a unidirectional prepreg in the longitudinal direction of the wire so that its fiber directions are parallel, the winding operation will be further improved. Although it is possible to perform the winding operation by hand, it is more efficient to roll it on a table while applying pressure using a metal plate.

The material for the coil spring of the present invention must have the following properties.

That is, prepregs are laminated in one direction and cured under pressure to produce a CFRP board with a thickness of 21 Il.

Fiber direction L/C/ from this board! am, 1 in the perpendicular direction
A test piece of 0 mm is cut out of gold, and the test piece is placed on a fulcrum moss with a radius of J mm to conduct a bending test. The fulcrum is / Oam apart, and an indenter is applied to the center of the fulcrum to apply a load, and the interlaminar shear strength (ILSS) is determined by the following formula from the cart P that will break.

ILSS=(9)P/(t)t) where t is the width and thickness of the test piece, respectively, and a prepreg with an interlaminar shear strength of 10 kg/- or more is used in the present invention.

Materials with a low value have a low load capacity even when formed into coil springs, and cannot be used in coil springs that are used under severe conditions such as in vehicles.

A prepreg having an interlayer shear strength of 10 kg/- or more may be used for all of the coil springs, but another prepreg may be used for the inner layer portion where shear stress is small.

In any case, the interlayer shear strength near the outermost layer is 10 kg/-
It is necessary to arrange the above prepreg.

An intermediate body before coil forming is prepared as described above, and the intermediate body is then molded into a rubber tube or a plastic tube. Although these test tubes are not essential, they are suitable for improving operability during molding.

The intermediate body is wound around a cylindrical mold. At this time, the winding operation must be performed carefully so that the prepreg winding end is not located inside the coil. The winding end in this case refers to a prepreg end that occurs in the longitudinal direction of the core material when the prepreg laminate is wrapped around the core material. If this winding end is located on the molded product, shear stress will cause the layer to peel off. Especially if it is located inside the coil, it will become a source of stress concentration and breakage or cracks will occur from this location, so it must be avoided.

The coiled spring of the present invention can be obtained by putting the thus-wound product into a heating furnace and hardening it under pressure.

The present invention will be explained below with reference to Examples.

Example 1 A prepreg manufactured by Mitsubishi Rayon Co., Ltd. [Pyrophil As
-'I10. Using one sheet of J, stack it to ±4'j0 and have a width of qoo
Dragon, length/! ;00-related sheet was created.

Separately, prepare an aluminum rod of diameter S, length / t 00, and prepreg sheet parallel to this rod /! ;00 direction was wound upward. Wrapping: I placed an aluminum plate with a thickness of 10 and was able to wrap the plate by sliding it parallel to the table surface without applying pressure.

The rolled rod-shaped intermediate body has a diameter of /U thickness/! ; Put this thing in a ma silicone tube with a diameter of 90 mm and a length of 30 mm.
Wrap the prepreg around the iron core with the end of the prepreg always facing towards the side. ? It was cured in an autoclave while applying a pressure of 1kglcv & for ℃ x a hour. ◎ When the entire tube was t-t and the dimensions of the coil spring were measured, it was found that the wire diameter / 7111% coil diameter / 00 sn, Pitzida Oms coil number da. *Amount was 5top.

When this coil spring was fitted with a jig and a load was applied at a speed of 1 spring/minute using Toyo Boldfin's Tensilon-NTM-/θT, it did not break even under a load of tSOkg.

A coil was made in the same manner as in Comparative Example/Example/, except that when winding it around the iron core, a part of the winding end was wrapped inside.
There was a peeling sound under a load of 4tIqokg! ; 40 kg
Comparative example: A coil spring obtained by molding in the same manner as in Example 1 using an epoxy prepreg with an ILSS value of g, skg/- was II.
! ; Destroyed with Okg.

Claims (1)

[Claims] l) A longitudinal fiber-reinforced resin coil spring in which a unidirectional carbon fiber/epoxy resin prepreg layer having an interlaminar shear strength of 10 kg/- or more is arranged at least near the outer surface) J) Unidirectional carbon fiber/epoxy having an interlayer shear strength of 10Ic9/- or more Pre-pack prepreg with ±3S0~
The coil spring according to claim 1, which is laminated in layers in a thickness of ±ss", wound around a core material, and then acid-formed into a coil shape.