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1、2.1.3 Cutting heat and temperature,2.1.3.1 Generation and transmission of cutting heat,2.1.3.2 Cutting temperature,2.1.3.3 Influence factors on cutting temperature,2.1.3.1 Generation and transmission of cutting heat,Cutting heat comes from the conversion of cutting energy. As shown in Fig.2.35, the
2、general cutting heat Q includes Qpthe hear from shear deformation energy, Qfthe heat from the chip-tool friction, and Qfthe heat from machined surface tool friction. The general cutting heat Q can be decomposed into chip heat Qch, tool heat Qc, workpiece heat Qw and surrounding medium heat Qf, . The
3、re is the relation :,Qp+Qf+QfQch+Qw+Qc+Qf (2.20),2.1.3.2 Cutting temperature,Through the balance of the deformation energy, friction energy generated in the cutting region and heat transmission, the cutting temperature may be calculated approximately. Taking the calculation of average temperature in
4、 the cutting region as an example: In a unit time the generated heat q is equal to the dissipated cutting power Pm, that is q=Fzvc/60 W (2.21) Here Fz main cutting force (N); vc cutting speed (m/min),(1) Calculation of cutting temperature,The temperature increment resulting from q is related to the
5、materials density and specific heat capacity c: Here p per unit cutting force (N/m2) c specific heat capacity (J/kgK) density (kg/m3), (2.22),2.1.3.2 Cutting temperature,2.1.3.2 Cutting temperature,When cutting plastic material, the maximum Temp is near the tool tip of the rake face. When cutting br
6、ittle material, the maximum Temp is near the tool tip of the flank.,2.1.3.2 Cutting temperature,There are several methods of measuring cutting temperature such as thermoelectric couple, heat radiation, coloring and infrared method etc. Among them the thermoelectric couple finds wide application. Nat
7、ural thermoelectric couple Synthetic thermoelectric couple,2.1.3.3 factors Influencing cutting temperature,Cutting temperature principally depends on the amount of heat generated in the cutting process, also on the amount of heat dissipation. There are several Influence factors on cutting temperatur
8、e : tool geometric parameters 、cutting parameters、work material .,(2) Measurement of cutting temperature,2.1.3.2 Cutting temperature,Experiential formula,2.1.3.3 factors Influencing cutting temperature,Discussion: The geometry of the cutting tool: The workpiece material The tool wear The cutting fluid,