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Using solid carbide straight end mills with TiAlN coating, A P20 steel at 41HRC is machined in the cutting speed range of 301 to 754m/min. The workpiece subsurface are examined using scanning electron microscope (SEM) and surface roughness tester. The results show that the white layer is produced in all of the cutting conditions tested, and the white layer thickness and surface roughness are dependent on the cutting conditions. The result obtained by analysis of variance analysis shows that feed rate and cutting speed are the most significant effects on the white layer thickness and surface roughness. Furthermore, the mathematical models for the white layer thickness and the surface roughness in high speed side milling of hardened P20 steel are proposed, respectively.

A P20 steel are machined in the milling speed range of 200 to 942m/min. The morphology and formation of the chips are investigated at various speeds. The serrated chips with adiabatic shear band are observed at a high milling speed. The transition from continuous to serrated chip formation is favored by the increase in work material hardness and milling speed. The study assumes that the chip segmentation is only induced by adiabatic shear banding, without material failure in the primary shear zone. Based on adiabatic shear theory, using the JC and the power material constitutive equation, the modified material model which takes into a strain softening is developed for prediction of the serrated chip formation. Experimental measurements are compared with the simulation results.

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The work investigates the structure parameters of adjustable subatmospheric pumping scraps device and oil feeder, which have extremely significant impacts on double feeder system in the deep-hole drilling process. Equations for subatmospheric zone pressure are derived herein using the siphon principle, and experiments are performed the trends of pressure on the single factor condition, which provide reasonable structure parameters for adjustable subatmospheric pumping scraps device. Oil feeder is studied based on the Euler column theory, and it can be optimized that is intermediate support, pilot bushing as well as sealing. The universal finite element software is used to design the structure of adjustable subatmospheric pumping scraps device and oil feeder, also reasonable structure design scheme of double feeder system core components is given.