China has now become the world’s largest automobile manufacturing country. However, judging from the processing status of automobile panel molds in China, most domestic manufacturers can only produce panel molds with relatively low requirements for profile accuracy and surface quality. The final dimensional accuracy and surface quality of the molds mainly rely on a large amount of manual grinding in the late stage [third stage] to ensure, resulting in low production efficiency. Therefore, vigorously improving the finish machining quality and dimensional accuracy of molds in China is of great significance for improving the manufacturing level of automobile molds in China.
From the on-site investigation of automobile panel mold processing, it is found that due to the high hardness of hardened steel molds and the small finish machining allowance, the phenomenon of the tool “not biting” the workpiece and slipping often occurs in mold finish machining due to improper selection of allowance. This phenomenon is particularly common in the processing of convex curved surfaces of automobile molds, resulting in many areas not being processed after mold finish machining. Finally, a finishing process is adopted after finish machining, or a large amount of manual grinding in the late stage [third stage] is relied on to ensure machining accuracy, which greatly reduces machining efficiency.
The reason for this phenomenon is that the cutting tool has a certain radius of curvature during the manufacturing process, and the existence of the cutting edge radius of curvature makes the material have a minimum cutting thickness during the machining process. When the cutting thickness in machining is less than the minimum cutting thickness of the material, the tool and the workpiece cannot perform normal cutting, but are mainly plowing and rubbing, which makes it difficult to ensure the machining quality and dimensional accuracy.
In recent years, the blunt radius of the cutting edge in the small cutting capacity of conventional milling processing in the impact of the gradual attention has been paid especially in the mold manufacturing and processing industry. Due to the high hardness of the mold material, commonly used material Cr12MoV ° quenched hardness of up to 55-62HRC, resulting in the tool cutting process cutting force is larger, let the knife phenomenon is obvious. And in order to improve the processing quality of the mold, mold finishing often use high cutting speed °, small depth of cut processing. Smaller finishing allowance (generally 0.05-0.20mm) and the blunt radius of the cutting edge of the tool is in the same order of magnitude, in order to as far as possible only through the milling process can meet the requirements of machining quality and accuracy, reduce the later artificial grinding time, the blunt radius of the cutting edge of the tool in the mold machining impact can not be ignored. Automotive mold finishing, due to improper selection of machining allowances and lead to the tool and the workpiece between the sliding phenomenon, reducing the automotive cover mold machining quality and mold precision, increasing the later manual grinding time.
Therefore, a systematic and in-depth study should be conducted on the sliding friction phenomenon between the tool and workpiece caused by improper selection of allowance in the finish machining of convex and curved surfaces of automobile covering die. Taking hardened steel Cr12MoV, a commonly used die material, as the research object, a method for determining the minimum cutting thickness of workpiece material is proposed by combining theoretical analysis and experimental methods, and the minimum cutting thickness values of Cr12MoV (58HRC) material at different cutting speeds are determined. On this basis, a prediction model of the limit cutting depth for die steel convex and curved surface machining considering tool deformation factors is established, which provides a minimum value for the selection of finishing allowance for automobile covering die, thereby avoiding the occurrence of sliding friction between the tool and workpiece, greatly improving the machining accuracy and mold closing accuracy of automobile covering die in China, and improving the machining status of automobile covering die in China.
Post time: Jun-25-2025