tailieunhanh - Kinematic Geometry of Surface Machinin Episode Episode 12

Tham khảo tài liệu 'kinematic geometry of surface machinin episode episode 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 8__ Accuracy of Surface Generation Accuracy of the machined part surfaces is a critical issue for many reasons. Deviations of the actual part surface from the desired part surface are investigated in this chapter from the prospective of capabilities of the theory of surface generation. Two major reasons often cause surface deviation When machining a part surface the entire generating surface of the cutting tool does not actually exist. In all cases of implementation of wedge cutting tools the generating surface of the cutting tool is not represented entirely but by a limited number of cutting edges. In other words the generating surface of the cutting tool is represented discretely. The discrete representation of the surface T of the cutting tool causes deviations of the actual machined part surface Pac from the desired say from the nominal part surface Pnom. Point contact of the part surface and of the generating surface of the cutting tool is usually observed when machining a sculptured surface on a multi-axis numerical control NC machine. When the surfaces make point contact then articulation capabilities of the multi-axis NC machine can be utilized in full. From this prospective point contact of the surfaces can be considered as the most general kind of surface contact. However point contact of the surfaces P and T also causes deviations of the actual machined part surface Pac from the desired part surface Pnom . Ultimately when the generating surface T of a cutting tool is represented discretely and the surfaces P and T make point contact then the deviations of the actual machined part surface Pac from the desired part surface Pnom are getting bigger. Sources for the deviations of the machined part surface from the desired part surface are limited to two major reasons only in a simplified case of surface machining. In the simplified cases of surface machining no deviations in the surfaces P and T configuration are observed.