METHOD FOR STRENGTHENING STIFFNESS OF STEEL SHEET FOR AUTOMOBILE AND MOLDED PART OF THE STEEL SHEET FOR AUTOMOBILE

摘要

PURPOSE: A method for strengthening stiffness of steel sheet for automobile using laser strengthening capable of attempting weight reduction of precision molded parts for automobile and improving strength of matrix of the steel sheet, and a molded part fabricated through the method are provided. CONSTITUTION: The method is characterized in that stiffness is given to the steel sheet by forming a specific shaped fusion pattern fused onto the surface of steel sheet matrix by heating through a pattern forming means in order to reinforce stiffness of a specific region of the steel sheet(400) for automobile, wherein stiffness is reinforced by directly irradiating a laser beam onto the steel sheet matrix through a welding head having superior Nd:YAG laser beam convergence to form a fusion pattern(401) through heating or forming a fusion pattern on the surface of the steel sheet matrix(400) through a welding head capable of forming a fusion pattern(401) on a relatively large area although convergence is lower compared to the former welding head, and the method not only reinforces stiffness, but also reduces weight without using of any separate member since stiffness is improved as structure of the fusion pattern part is being reinforced compared to other parts by directly heating the steel sheet matrix for automobile, thereby locally forming a fusion pattern.