Key Engineering Materials Vols. 407-408

Abstract: . In order to improve quality of deep hole finishing, a new method of deep hole honing based on squeeze film technology is put forward. According to fluid lubricates theory, Renault equation of deep hole honing squeeze film damper (SFD) is established, squeeze film force is solved by immense short bearing theory and the effect of the eccentricity of SFD on the damping coefficient is analyzed by MATLAB. Spindle of deep hole honing with SFD is designed based on theory research, and experimental research is carried on. Experimental result shows that SFD with reasonable design parameters has excellent damping function to honing spindle, and it can make vibration of honing spindle reduced 20%～30% and quality of deep hole machining improved 10%～20%.

Abstract: Dual-lapping was a process to planarize the surface of the sapphire wafer, the nature of surface&subsurface damage and the surface uniformity was depended on the material removal mode and materials removal ratio. Material removal mode was studied in this paper, and the model of material removal was set up too. The SEM was used to scan the processed sapphire surface and the different removal style (two body and three body) were discovered. This research provided valuable insights into the material removal ratio and the dependence of lapping-induced damage on dual-lapping conditions, the asymmetry of abrasive granularity brought on the different materials removal mode and the surface asymmetry. The model was set up to qualitative analysis the material removal ratio in dual-lapping of sapphire, obtain the reasonable MMR and optimize the surface quality and the planarization result.

Abstract: The process technique on abrasive jet finishing process with wheel as restrain was investigated by experimental. The effects of different particle size, abrasive concentration, machining cycles, the velocity of grinding wheel and medium type on surface quality were analyzed. Experiments were performed with plane grinder M7120 and workpiece material 40Cr steel. The machined surface morphology was studied using Scanning Electron Microscope (SEM) and microscope and microcosmic geometry parameters were measured with TALYSYURF5 instrument respectively. The experimental results under percentage 10 abrasive concentration, Al2O3 abrasive particle with W7 size and machining 20～30 circles showing the novelty process method, not only to attain higher surface form accuracy, to diminish grinding defects such as severely deformation, surface layer pollution and ground burnout, but also to can acquire efficiently free defects finishing surface with Ra0.15～1.6µm and finally achieve high efficiency, high precision and low roughness values. Furthermore, integrate grinding process and abrasive jet finishing process into one feature.

Abstract: The grinding hardening is a new surface heat treatment technology using grinding heat in which induce martensitic phase transformation in the surface layers of annealed or tempered steels to achieve surface strengthening processes and integrate the surface hardening process with the grinding precision machining. In the paper, a thermal model to describe this process has been presented from the thermal partition modeling and has been used to predict subsurface time–temperature profiles in the dry cylindrical grinding crankshaft using cubic boron nitride (CBN) wheels. The grinding hardening experiment was carried out in precision cylindrical grinder M1420E, using work-piece material 42CrMo4 and CBN grinding wheel under dry grinding condition. The experimental results showed the theoretical model is agreement with experimental results and the model can well forecast the grinding hardening depths.

Abstract: The magnetic abrasive finishing process of thin sleeve of Al alloy with different diameter is studied based on self-adaptive characteristics. Some technical innovations are done such as fixing smooth magnetic mandrel or slot magnetic mandrel and so on in the workpiece interior for improving the structure style of the working space and characteristic of magnetic field. Experiments on thin sleeve of Al alloy are done and their finishing effects are contrasted. Research results indicate that fixing slot magnetic spindle in the workpiece interior can increase efficiency and improve quality for large thin non-magnetic sleeve.

Abstract: In this paper, a critical study into the dynamic form of abrasive particles through polishing are made, which are under “inconsistent curvature contact” status. In this system, some abrasive particles are colored up and mixed with ordinary ones, by utilizing transparent working surface and stroboscopic light as well; motion state of abrasive particles can be photographed by high speed shot technology. This method can get serials of images while polishing. By using digital image processing technology, distribution of abrasive particle field can be obtained finally. In this paper, the abrasive particles field is researched to obtain the perfect abrasive particle field after purposefully control. Then the influence of the removed material caused by abrasive particles field can be improved, so it can provide strong theory foundation and practice guidance to surface polishing practice.

Abstract: With four-probe and laser light scattering techniques, we have studied the dependencies of the conductivity and the particle sizes of p-toluene sulfonic acid doped polypyrrole on the mechanical grinding time. As the chemically synthesized polypyrrole was mechanically grounded in a mortar from 0 to 8 hours, its conductivity decreased from 607 to 10 S/m while and its particle size decreased from 27 to 4 m. If the mechanical grinding continued, the conductivity of the polymer was found to be up to 1680 S/m. Our results have demonstrated that mechanical grinding is an effective method to control the conductivity of the p-toluene sulfonic acid doped polypyrrole.

Abstract: During cylindrical grinding process, the geometric configuration and size of the edge contact area between the grinding wheel and workpiece have the heavy effects on the workpiece surface integrity. In consideration of the differences between the point grinding and the conventional high speed cylindrical grinding, the geometric and mathematic models of the edge contact area in point grinding were established. Based on the models, the numerical simulation for the edge contact area was performed. By means of the point grinding experiment, the effect mechanism of the edge contact area on the ground surface integrity was investigated. These will offer the applied theoretic foundations for optimizing the point grinding angles, depth of cut, wheel and workpiece speed, geometrical configuration and size of CBN wheel and some other grinding parameters in point grinding process.

Abstract: Composite when machined with conventional technique often results in fibre damage, interlaminate failure, poor hole quality and high tool wear rate. The flexibility and cool cutting characteristics of the AWJ make it an important tool for cutting applications of new materials such as composites. It has been shown that using AWJ cutting with optimal parameters for Bakelite, interlayer GFRP and normal GFRP can be a viable and effective alternative with good kerf quality and few problems such as thermal effects, delamination and burr. The empirical models of the levert of GFRP has revealed that AWJ technology has a great of advantages on machining complicate shaped and interstitium workpieces

Abstract: . Based on the dynamic simulation module of CutPro, the dynamic cutting forces and chatter limits for tee slot milling were predicated by setting the geometry of a tee slotting cutter. The chatter stability lobes under a given axial depth of cut are obtained by further programming, which is essential for chatter-free tee slot milling. A methodology of cutting conditions optimization for tee slot milling is presented, in which the minimal cutting time is used as the target function and the stability limits are introduced into the constraint conditions to reflect the vibration characteristics of milling operation. This optimization method has been validated by experimental tests.