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Tải xuống
Ngày nay, nhấn mạnh hơn được đặt trên machinability của một thành phần, nhưng thuật ngữ này là một mơ hồ, có nhiều ý nghĩa khác nhau, tùy thuộc vào yêu cầu các kỹ sư sản xuất. Trong thực tế, biểu thức machinability không có một định nghĩa có thẩm quyền, mặc dù thực tế là nó đã được sử dụng trong nhiều thập kỷ. Năm 1938, Ernst trong cuốn sách của ông về Vật lý của cắt kim loại | Machinability and Surface Integrity 287 lobing18 or elliptical state may have not have proven to be detrimental to its prospective overall in-service performance. In reality there might be a whole host of reasons for a machined part to vary in its radius - for a stated cross-sectional plane. The following list attempts to show where and why radial differences occur Machine tool and its production processes - inducing some form of rotational imperfections from either the machine tool workpiece system Release of strain or that induced into a workpiece -the former case may be the result of releasing the part from its clamping pressure while the latter may result from plastic deformation promoting localised surface residual hoop-stresses 19 Induced radial vibration - potentially resulting from cutting forces and its effect on rigidity in association with both tool geometry and cutting edge displacement i.e. see Fig. 152 Circumferential surface texture - created by the lasting effect resulting from the recent production process. It has been alluded to above that the machine tool and particularly its spindle can create machine-induced inaccuracies of various kinds onto the machined workpiece s harmonic roundness 20 some of these factors include Spindle imbalance - introducing dynamic lower-frequency harmonics on the part Cutting forces - can dynamically affect the machining process causing a series of high-frequency harmonics to be superimposed on the lower-frequency harmonic resulting from imbalance Fig. 152 Thermal growth effects - changing both the spindle s growth axially and causing modifications of an elastic nature to the relative axis-orthogonalities 21 of the machine tool - which in turn creates harmonics on the machined part Working clearances and motor-drive configurations - this is necessary to allow for relative thermal growth and beaing component running-fits -within the spindle headstock assembly which are exacerbated by the type of motor drive system .
