Abstract
Recent die production process has to meet "Super" low cost, "Super" short - term delivery and globalization of the worldwide simultaneous production. To realize above ideas in the process of die production, we have been tackling the technical innovation, which is "One Time TRAIAL and NO REPAIR" in the die making process. To realize above concept in the die production, high accurate machining which minimizes hand finishing work, has become essential. As for this reason, we consulted on the new process of reforming the conventional machining.
Explaining the process of fixed 5-axis machining, for the outer panel die which has strict requirements for smooth surface after machining process, we have worked on target under Rz=3m. Moreover, we have aimed the progress of the high-speed machining process, which is making use of cBN tool (cutting tool material)´s particularity. Aiming for the 800m/min cutting speed, we put incline machining process and 5-axis process machine´s maximum spindle speed (15,000min¯¹) together. Furthermore, by combining radius tool, we have achieved smaller inclination angle, and resulted in accurate machining with little load. Therefore, we have developed the simultaneous 5-axis process, which can hold milling point constant and control the contact angle constant.
After improving the smooth surface by above mentioned activity, we faced the new problem of reciprocating bump appeared in the process of the cutting track route. This is caused by the two different process condition between the up-cut and the down-cut. To get rid of this difference, we have decided to adopt one-way milling process, which is down-cut only, as the result of this.
Moreover, improvement activity of the simultaneous 5-axis process has been brought forward. Simultaneous 5-axis consists of X-axis, Y-axis, Z-axis, B and C pivot shaft. The intersection point of this B and C-axis becomes the pivot point, and the accuracy between the actual milling machine and the NC date became important to achieve the accuracy assurance. In addition, to assure surface quality keeping the velocity change of the cutting edge in smooth condition was the most important issue. This will create the smooth change of tool axis vector. From the result of the trial process, the cutting track mark occurred from the convergence change of the B-axis angular. The machining result after counter measures, to NC data showed that the problem caused by the B-axis improved. But, the new problem of the cutting track mark arose on the reversal portion of C-axis. This was caused by the accuracy of the milling machine. The cutting track was finally found to be 4-axis process in the die machining process caused by the small change which was m order in the NC data and the milling machine unit. At the present time, we have been developing the simultaneous 4-axis process in order to achieve the high-speed cutting process even when fixing the C-axis in the die machining process. The trial result of the combination between one-way process and the simultaneous 4-aixs was as follows. Finally the machined surface smoothness became under Rz=3m and achieved the smooth target of die cutting process.
Keywords: Radius-Tool, Cutting, Fixed-5Axis, Simultaneous-4Axis, smoothness