볼트형 피에조 센서를 활용한 피어싱 펀치의 얼라인먼트 불량 검출에 관한 연구

A study on the detection of misalignment between piercing punch and die using a bolt-type piezo sensor

Piercing is the process of shearing a circular hole in sheet metal, whose high shear force makes it difficult tosecure the durability of tools. In addition, uneven clearance between tools due to poor alignment of the piercing punchcauses accelerated die wear and breakage of the tool. This study reviewed the feasibility of in-situ determining alignmentfailure during the piercing process by analyzing the signal deviation of a bolt-type piezo sensor installed inside the toolwhose alignment level was controlled. Finite element analysis was performed to select the optimal sensor location on thepiercing tool for sensitive detection of process signals. A well-aligned piercing process results in uniform deformation inthe circumferential direction, and shearing is completed at a stroke similar to the sheet thickness. Afterward, a sharpdecrease in shear load is observed. The misaligned piecing punch leads to a gradual decrease in the load after themaximum shear load. This gradual decrease is due to the progressive shear deformation that proceeds in thecircumferential direction after the initial crack occurs at the narrow clearance site. Therefore, analyzing the stroke atwhich the maximum shear load occurs and the load reduction rate after that could detect the misalignment of the piercingpunch in real-time.

Piercing is the process of shearing a circular hole in sheet metal, whose high shear force makes it difficult tosecure the durability of tools. In addition, uneven clearance between tools due to poor alignment of the piercing punchcauses accelerated die wear and breakage of the tool. This study reviewed the feasibility of in-situ determining alignmentfailure during the piercing process by analyzing the signal deviation of a bolt-type piezo sensor installed inside the toolwhose alignment level was controlled. Finite element analysis was performed to select the optimal sensor location on thepiercing tool for sensitive detection of process signals. A well-aligned piercing process results in uniform deformation inthe circumferential direction, and shearing is completed at a stroke similar to the sheet thickness. Afterward, a sharpdecrease in shear load is observed. The misaligned piecing punch leads to a gradual decrease in the load after themaximum shear load. This gradual decrease is due to the progressive shear deformation that proceeds in thecircumferential direction after the initial crack occurs at the narrow clearance site. Therefore, analyzing the stroke atwhich the maximum shear load occurs and the load reduction rate after that could detect the misalignment of the piercingpunch in real-time.