D. Li

Multiscale Modeling Study on the Nanometric Cutting Process of CaF2

The hierarchical approach of multi-scale modelling was adopted to study the nanometric cutting process of calcium fluoride. Then fly cutting experiments of CaF2 were performed to analyze the influence of cutting speed upon the surface roughness of CaF2. The results of FEM simulations show that larger negative rake angle and larger cutting edge radius lead to lower tensile stress in the cutting region. Tangential cutting force will first increase with an increase of negative rake angle and cutting edge radius, and then start to decrease with them. The tensile stress in the cutting region will increase with cutting depth at first, and then become stable when it reaches a certain extent. The specific cutting force increases rapidly with decrease of cutting depth, showing an obvious size effect. Within the range of cutting speeds adopted in the simulations, cutting speed has little influence on the tensile stress in the cutting region. And the results of fly cutting experiments show that cutting speed has little influence on the surface roughness of a machined surface under the cutting speeds adopted. This verifies the validity of the simulation result to some extent.

Finite Element Method Predicts the Distribution of Cutting Temperature in Diamond Turning

In this paper, a coupled thermo-mechanical FE model is proposed to simulate the cutting temperature’s distribution produced in diamond turning. Simulated results indicate that the heat converting from plastic work has prominent effects on the distribution shape of cutting temperature field, and with an increment in cutting velocity, the locating site of maximal cutting temperature shifts from the contact area between tool tip and chip root to the contact area between rake face and chip. Cutting edge radius has minute influence on the distribution shape of cutting temperature field, but the bigger the cutting edge radius is, the higher the maximum cutting temperature in cutting region. Rake angle also has slight effects on the maximal temperature when it is more than 10○. While clearance angle reaches to 6○, the maximum cutting temperature approaches the smallest.

Experiment Research of Polishing Capability of Magnetorheological Finishing with a Small Permanent Magnet Ball-End Tool

In order to resolve the difficulty in polishing work of complex shape, a new magnetorheological finishing (MRF) technology with a small permanent magnet ball-end tool is developed. Rotary symmetrical magnetic field generated by the small permanent ball-end tool, stiffen a magnetic fluid which is delivered by a slender needle tubing, in contact with a workpiece. The permanent magnet tool is hold by a slender cylindrical shank, so it won’t interfere with workpiece when polishing deep concave cavity. A prototype apparatus is established to study the processing characteristics of this polishing method. MRF spots are taken on stationary workpiece to study the influence of several processing parameters on the material removal function, such as, spindle speed, included angle and minimum gap between polishing tool and finishing-surface. A 3×3mm square on a fused quartz (FS) is polished and the surface roughness decrease from 81nm Ra to 1.5nm Ra after polishing for 100min.

The Experimental Investigation of Face Grinding of Al2024/SiCp with Electroplated Diamond Wheel

In this paper experiments of the face grinding of Al2024/SiCp through the use of electroplated diamond wheel were carried out. The results indicated that high quality processed surface was achieved by face grinding machining, under the experiment conditions of this paper, the surface roughness was between Ra0.185 μm and Ra0.512μm, and the residual stress of processed surface was compressive stress. Grinding parameter had little effect on tangential force and normal force. Axial grinding force increased with the increasing of grinding depth and was stronger than grinding forces in other two directions.