Method for forming internal threads of composite material

Abstract

The invention relates to a method for forming the internal threads of a composite material, which comprises: circumferentially winding a nonwoven fabric impregnated with resin on the surface of a threaded part of a mandrel; spreading a resin substrate mixed with inorganic material crystal whiskers on the circumferentially wound nonwoven fabric layer, wherein the height of the resin is no lower than the top of the teeth of the threads of a mold; circumferentially paving a reinforcing unidirectional fiber fabric on the surface of the mandrel, wherein the fiber direction of the reinforcing unidirectional fiber fabric is consistent with that with the mandrel and the thickness of the reinforcing unidirectional fiber fabric is no greater than one third of the height of the teeth; winding reinforcing circumferentially wound fibers on the surface of the unidirectional fiber fabric, wherein the belt width is no greater than the thread pitch of the threads; spirally winding tube body fibers to a required thickness; and performing curing and demolding. In the structure, a method combining the reinforcing fiber unidirectional fiber fabric and circumferential winding to form the internal threads of a composite material tube and the reasonable distribution of the reinforcing fibers on the thread tooth part in a load bearing direction reinforces the resin substrate, so the internal thread part has a strength high enough for threaded connection.

Description

technical field [0001] The invention relates to a method for forming an internal thread of a composite material, in particular to a method for forming an internal thread of a fiber-reinforced composite material pipeline. Background technique [0002] In petrochemical, machinery manufacturing and other fields, the application of composite materials is increasing, and the connection problems of various structural parts often appear. When conditions permit, the composite thread connection method is a widely used connection method. At present, the molding of FRP threads usually adopts methods such as mold pressing or laminate processing. For the winding-molded composite pipe, the production efficiency can be effectively improved by winding the internal thread. However, it is difficult to reasonably distribute the fibers on the thread teeth through the traditional winding molding method; in addition, because the resin is in a flowing state before the thread groove is solidified...

AI Technical Summary

Problems solved by technology

However, it is difficult to reasonably distribute the fibers on the thread teeth through the traditional winding molding method; in addition, because the resin is in a flowing state before the thread groove is solidified and formed, it is easy to cause missing teeth and incomplete tooth profiles of the thread, and the thread The low hardness of the middle resin-rich area is also easy to cause damage to the threaded teeth. These structural defects will affect the strength and sealing performance of the threaded part, thereby affecting the connection strength of the composite material pipe.

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