Đang chuẩn bị liên kết để tải về tài liệu:
Friction and Lubrication in Mechanical Design Episode 1 Part 8

Tham khảo tài liệu 'friction and lubrication in mechanical design episode 1 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Thermal Considerations in Tribology 155 0.0080 0.0075 0.0070 0.0065 0.0060 0.0055 0.0050 0.0 0.2 0.4 0.6 0.8 Slide I Roll 1.0 Figure 5.25 Tmn q versus slide roll ratio steel-oil-steel rolling speed 400 in. sec R1 R2 1 in. pmax 100 000 psi . siderable difference between the film and solid temperatures. Figure 5.27 represents the case of a metallic solid with an insulative surface layer in contact with another layered solid having an opposite combination of thermal properties. It can be seen from the figure that the heat partition is highly dependent on the ratio where Hd h2 - h0l and Hgn The latter is kept constant to show the main influence of the difference in surface layer thicknesses. The existence of surface layers strongly deviated the heat partition from the dry sliding condition. This phenomenon could be explained by the cooling mechanism in the contact zone by a shallow region near the surface which mainly incorporates the layer thickness. Figure 5.27 also demonstrates the possibilities for equalizing the heat partition between the moving solids by controlling both thermal properties and thicknesses of surface layers. Negligible sliding is assumed in this case. Figure 5.28 shows the variation in the maximum temperature rise in the contact zone and the solid surfaces with respect to The contact 10 psi Figure 5.26 Maximum temperature rise versus maximum pressure for 50 sliding steel-oil-steel rolling velocity 400 in. sec R R2 I in. . -1.0 -0.5 0.0 0.5 1.0 6 Figure 5.27 Heat partition versus Hd Haw rolling velocity 2000 in. sec 1 .02 in. Kị Km. K0i K2 . 1 ave- 10 4 in. . 156 Thermal Considerations in Tribology 157 Figure 5.28 Tmiir. qi versus rolling speed 2000 in. sec 1 .02 in. K Km Km K2 . Ki ave 10 4 in. . zone temperature is almost identical to the solid surface temperature which carries the conductive surface layer. The generalized equation for heat partition in lubricated line contact problems which has been derived for steady-state conditions is .