자동차 브라켓 프레스 이형복합공법 및 CMT 용접 적용에 따른 품질 평가

Abstract

In this study, weldability of CMT process applied automobile bracket with press multi composite method have been evaluated for productivity improvement. Since there is no case of applying multiple shapes into one press mold, applying multi-shape composite method with guaranteed weldability would contribute to the improvement of productivity responsing to the 4th industrial period. This research is focused on automobile sash production process.

The purpose of this study is to evaluate welding quality of CMT welding process and composite mold for automotive bracket parts. Newly designed mold model has been has been analyzed and fabricated. The weldability of CMT process has been evaluated by comparing the process with CO2 welding.

From the result of the molding analysis of mold release mold, cracks were occurred due to the fatigue in the corner R part in OP10 and 0P20 process. However, the quality was secured by using CAM CUT in OP30 process.

From the result of the stiffness evaluation of the die casting mold, the MAX FORCE of each section in the OP10 process was 94.5 tf, 218.3 tf , 11.2 tf, 133.3 tf in die, pinch, blanking holder, pad, respectively. In addition, gross weight was 20N. In the OP20 process, the MAX FORCE of each zone was 60.3tf in pinch, 132.4tf in pad, 192.8tf in die, and the total weight was analyzed as 20N. Strength and stiffness were considered as sound values ​​in both processes.

From the result of evaluation of weldabiltiy of molds for single mold and single mold, bead profiles of LH / RH CMT welded mold of mold release mold did not show sagging and humpping on the bead surface. Cross section of bead profiles showed no defec such as undercut, porosity, cracks, etc. Bead profiles of LH / RH CO2 welded part of single mold, no sagging and humping was observed on the top bead, and cross sectional inspection satisfied penetration depth, undercut, linear step, pore and cracks.

Consequently, fabricated molds based on molding and its stiffness have been secured the excellent welding characteristics. The result satisfied the standard of welding quality evaluation. Compared to past production system which produces 4 parts in separate process, this study combined them in to one process. Moreover, the molding process has been reduced to 3 parts from 6. This result can be expected to reduce labor cost through the simplification of production process.