共查询到17条相似文献,搜索用时 125 毫秒
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冷轧时轧件塑性变形热和摩擦热是导致轧件温度升高的两个主要原因。本文采用包含滑动摩擦和粘着摩擦在内的混合摩擦模型精确地计算了轧制区的摩擦热,综合考虑轧件塑性变形热,推导了轧件温升计算公式。 相似文献
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本文依据轧制塑性加工中的滚一滑摩擦机理建立一个新的摩擦力概念,并在此基础上给出一个相应的摩擦力计算公式。文中用该公式对轧制咬入过程中的摩擦力进行了计算。并以实验对其计算结果进行了验证。同时还对计算结果进行了分析。文中的结论可供有关研究人员参考。 相似文献
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冷锻工艺已经成熟,温锻及温锻与压力焊的结合已成功应用,锻件精化也有进展,新的锻压设备相继出现,板材成型技术日臻完善,过程仿真与模拟及工艺过程设计专家系统正积极应用。 相似文献
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介绍国内外超塑性成形加工中的润滑剂的品种、特点和使用方法。同时也介绍了润滑机理及其超塑性成形加工中摩擦的特点。 相似文献
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通过以一定法向压力相互接触的滚子与平面在摩擦过程中的物理变化和几何关系,揭示滚动摩擦原理,推导和建立滚动摩擦系数的计算公式,在完成中心动力作用下的摩擦系数计算公式后,继续用计算法确定周动力作用下的滚动摩擦系数。 相似文献
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通过以一定法向压力相互接触的滚子与平面,在滚动摩擦过程中的物理变化和几何关系,揭示滚动摩擦原理,推导和建立滚动摩擦系数的计算公式,用计算法确定滚动摩擦系数且与实验法数值对照。 相似文献
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Material characterization and wear evaluation of the original and replacement pistons and cylinder liners from a Tiger 131 are reported. The original piston and cylinder liner were operative in the Tiger engine during WWII. The replacement piston and cylinder liner were used as substitutes and were obtained after failure in 2 h of operation in the actual engine. Material characterization revealed that the original piston was aluminum silicon hypereutectic alloy approximately matching the specification of RSA-419 AE, with a silicon content of 19.92 wt%. The replacement piston was aluminum copper alloy with a low silicon content of 0.73 wt%, approximately satisfying specifications of Al 2031 and Al 2618-T6. Scuffing, material removal, and ploughing were observed in the replacement piston and cylinder liner. These failures were attributed to inadequate piston material and design. The replacement piston average surface roughness was 9.09 μm and for the replacement cylinder liner it was 5.78 μm. Characterization results showed that both the original and replacement cylinder liners consisted of mostly iron, which is indicative of cast iron, a common material for this application. 相似文献
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A new model of surface flattening is developed for cold metal rolling in the mixed regime. Longitudinal surface roughness is modeled by two separate wavelengths. The new model follows the asperity crushing analysis of Sutcliffe (1999) for unlubricated rolling but additionally includes a hydrodynamic model to account for the effect of the lubricant. The effect of various parameters including speed, reduction in strip thickness, roughness wavelength and lubricant properties is examined. The results show similar behavior to previous models of mixed lubrication, with a speed parameter As having the most influence, and confirm the results for unlubricated rolling that the short wavelength components of the surface roughness persist more than the long wavelength components. The predicted changes in roughness are in good agreement with experiments. 相似文献