Investigating the Characteristics of Curve Surface and Tool Wear in High Speed and Green Milling for Mold Steel

• Main Authors: Huang, Ping-Cheng, 黃炳誠
• Other Authors: Chien, Wen-Tung
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/28113207723961692977

碩士 === 國立屏東科技大學 === 機械工程系所 === 97 === The purpose in this study is to investigate the usage of high speed and green milling method in fabricating a curve surface of mold steel SKD61, such that the high speed cutting can replace the polishing process and the green cutting can achieve the same manufactured effects as the traditional cutting process. Therefore the mold fabrication time will be shortened and the manufacturing costs will be reduced. The objective in this study is to reach the same fabricated characteristics for surface roughness of workpiece as the polishing process, while the constraint for tool flank wear is considered at the same time. A comparison for surface roughness of a curve surface between theoretical values and experimental results are conducted. Then the Taguchi method is used to arrange experimental sets in conducting high speed cutting curve surface, an optimized parameters combination to achieve minimum surface roughness (Ra and Rmax) and another optimized parameters combination to achieve minimum tool flank wear (VB) can br found respectively. With those optimize parameters, the different type of cutting fluid introduced has been performed for the observation the effects on surface roughness and tool flank wear. Finally a similar effects is investigated with green cutting. In conducting high speed milling a convex curve surface to perform the objective of a minimum surface roughness, an optimized parameters combination is obtained as A3 (cutting gap is 0.02mm), B1(feed per tooth is 0.04mm/tooth), C3(cutting speed is 540m/min), D2(depth of cut is 0.1mm) and E3(a large amount cutting fliud) such that a minimum value 0.108μm for Ra and a minimum value 0.642μm for Rmax are achieved to meet the required polishing standard. If the objective of a minimum tool flank wear is performed, an optimize parameters combination is obtained as A3(0.14), B3(0.1), C3(610), D(0.05) and E2(high pressure air) such that a minimum value 0.014mm for VB is achieved. According to the different type of cutting fluid introduced , when applied with a large amount cutting fluid can produce the best quality of surface roughness. However if the requirement of surface roughness in a manufacturing process is to reach the polishing standard, those methods by using a high pressure gas, a micro amount spraying fluid, or dry cutting namely green cutting, can achieve the objective and reduce the cost of using a large amount of cutting fluid. If the goal is to find a minimum tool flank wear, the types of dry cutting and pressure gas can be chosen. If both the surface roughness and the tool flank wear are treated as the requirements, a high pressure gas is the best way to be applied. It can be proved that the green cutting can achieve the same polishing standard in a manufacturing process as a traditional process with a large amount cutting fluid. This contribution can provide a useful reference in mold fabrication to improve its market competitiveness.