Papers by Author: Jun Zhong Pang

Abstract: 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.

Abstract: 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.

Abstract: In order to drill a deep steps hole with a big belly in hard-cutting material parts, a special boring cutter is designed by analyzing cutting technology of this kind of parts. On the basis of single-tube inner chipremoval ejector drill (SIED), a new tool radical movement mechanism is pulled by a wedge plate installed inside the tool rod at one end of the rod and plate is driven horizontally by a motor controlled by a numerical control device. A straight hole whose diameter is same as the minimum one of the steps holes is firstly machined by an entity drill. And then the tool is used to get the big belly hole in the middle of the straight hole and begin to move radically at the same time as axial feed just in the location of belly. The tool is retreated to the original position at the end of the big belly. Experiments show that this kind of tool can not only drill belly holes effectively but also improve the processing quality.

Abstract: 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.