Importance

Loading Importance Indicators...

Abstract

A two-part system for reinforcing a hollow structural member and its method of use are provided. Part A of the two-part system is formed by adding a filler and unexpanded, thermally-expandable microspheres to a liquid thermosetting resin, such as an epoxy resin, in a quantity sufficient to produce a dough-like mass which can be readily kneaded. Part B is formed by adding a filler and a colorant, such as carbon black, to a liquid curing agent, again forming a dough-like mass. The curing agent is compatible with the thermosetting resin to promote cross-linking of the thermosetting resin upon contact with the curing agent. A hollow structural member is cleared of debris of the like and may be preheated to enhance the rate at which the thermosetting resin cross-links. The two parts are blended together until a reactive third dough of substantially uniform mixture is formed. The uniformity of the blending is confirmed when the reactive third dough attains a uniform color intermediate the color between the colors of part A and part B. The blended reactive dough is then packed into the cavity of the cleaned structural member. The cavity is then preferably closed with a closure plate. As the curing agent promotes the cross-linking reaction of the thermosetting resin, the exothermic reaction generates heat which is transferred to the unexpanded, thermally-expandable microspheres, causing the microspheres to expand. The expansion of the microspheres causes the reactive dough to rise, substantially filling the cavity. As the reactive dough cures, it bonds rigidly to the surfaces which it contacts. The reactive dough is allowed to fully cure, whereupon a solid lightweight reinforcement member rigidly bonded to the structural member is formed. The reinforced structure has good strength and energy absorption characteristics. The present system is particlarly suitable for use in reinforcing motor vehicle structure which have been cold-worked during repair of collision damage.

Loading the Abstract Image...

First Claim