Advanced Materials Research Vols. 102-104

Abstract: It is important for the CNC machining process of the typical sliding block parts with special shape in automobile mold. The mold structure analysis is developed, and the process schemes and cutting parameters of the mold machine are optimized during producing mold based on the mold structure analysis. The present analysis can solve the difficult processing problems of the complex parts and improve the process quality and production efficiency. is the method has the advangtages of advanced, scientific and practical etc..

Abstract: In order to realize STEP compliant NC manufacturing, STEP-NC (ISO 14649) has been developed over last decade by the International Standard Organization as a new data model for CNC programming. This paper proposes a framework for STEP compliant NC programming of the freeform surfaces. The system is supposed to read the CAD model produced by commercial CAD/CAM software and represented in STEP format, prepare the process information, and finally generate the STEP-NC compliant program. Major issues relating to CAD data extraction, toolpath calculation and NC program generation are presented.

Abstract: Researches on bending property of the AZ31B magnesium alloy sheet have been focusing on the loading methods and their own performance, while the temperature is less concerned in the past. In this paper, the law of the springback with the temperature changing was especially studied. In addition, the forming characteristics of the microstructure at various temperatures were researched. The experimental results indicated a nearly linear relationship existing between temperature and springback owing to the changing characteristics of the microstructure. A formula for calculating the bending springback by temperature of 0.8mm magnesium alloy sheet was obtained, which was according to the data obtained on the basis of physical experiments.

Abstract: According to liquid-solid two-phase flow model for the complexity of adaptation, as well as the impact of the concentration of particles, and we put forward a new method of considering the turbulent influence of particle concentration. Basing on the different turbulent control methods of the liquid-solid two-phase flow, we established the unified second-moment turbulence model. Using fluent software can realize turbulence model considering the particle pressure’s influence on particle’s concentration, and solve the problems of particle concentration and the flow passage control method. The simulation results showed that considering the concentration of particle’s influence on the pressure of the solid phase can accurately express the model of liquid-solid two-phase turbulent flow pattern.

Abstract: Fluid magnetic abrasive (FMA) is a new precision finishing process. It has the capability of processing free shape surfaces and complex cavities. Due to its strong adjustability and controllability, FMA could be regarded as the final process of machining which could greatly improve the surface quality of workpiece. The paper first introduces the component and machining mechanism of FMA, secondly it describes the model of the material removal in the process, thirdly it presents the devices of FMA polishing. At the end, a grinding head tool based machining mode is proposed for realizing the polishing of internal cavity.

Abstract: Lapping processes of single crystal sapphire are investigated in relation to crystallo- graphic orientation, the influence of the crystal anisotropism under different lapping liquid concentration, loading forces on materials removal rate and roughness in sapphire lapping is discussed. C-plane(0001),M-plane ( ),R-plane ( ),A-plane ( ) sapphire wafers were used for lapping experiments, experimental results show that Surface roughness is depend on the fracture toughness, surface orientation with higher fracture toughness such as C-plane would get better roughness during lapping, material removal rate of R-plane is the lowest in four planes, it is for elastic modulus and fracture toughness of R-plane are less than other three planes.

Abstract: In this paper, the effect of minimum chip thickness on cutting temperature in micro-end- milling of aluminum alloy Al2024-T6 using a tungsten-carbide cutter are investigated and analyzed. The three-dimensional coupled thermal-mechanical finite element model is adopted to determine the effects of varying depth of cut on cutting temperature considering size effects. The simulation results show that the cutting temperature in micro-end-milling is lower than those occurring in conventional milling processes. When the depth of cut is approximately 40% of the cutting edge radius, there is no chip formation. The maximum temperature occurs at the contact region between micro cutting edge and workpiece, which shows an obvious size effect. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6 with a high precision infrared camera. The influence of various cutting depths on cutting temperature has been verified in experiments. The experimental measurements results are in a good agreement with the simulation results.

Abstract: Multi-point impulse tests, which could determine the transfer function of each point, were carried through on vertical and horizontal direction of sphericalguide-slider joint surface by DATRAN dynamic analyzer. Multi-point impulse tests could determine the transfer function of each point. In order to determine the single-DOF mode of the sphericalguide-slider joint surface, the top surface and one of the flanking surfaces of the sliding block were selected as test-object. When the amplitude of each point on the same surface is mainly equal with each other, the corresponding mode could be judged to be single-DOF mode. The experiment conclusion would be a foundation for the future dynamic simulation.

Abstract: A Kumar-type constitutive relationship of TA15 alloy was investigated by non-linear regression analysis, and the equations were established based on test data from hot process simulator. Applying this constitutive equation in commercial FEM software of SFTC/Deform, the hammer forging process of TA15 alloy beam was simulated, meanwhile the final shape of forging piece, the hammering times, the height reduction variation and the maximal effective stress variation along with forging time were predicted. The hammer forging test was carried out and the test results showed that the simulation based on Kumar-type constitutive relationship meet the practical need to a great extent.

Abstract: Generally in the drilling of micro and small hole such as nozzle, problems frequently occur in terms of burr formation at the cutter exit, breakage of the drills and degradation of machining accuracy. A recent and promising method to overcome these technological constraints is the use of ultrasonic vibration drilling. This paper presents the design of an ultrasonically vibrated tool based on tailstock of lathe and the experimental investigation of ultrasonically assisted drilling of 3J1 stainless steel. The location accuracy of entering drilling and linear of drill were measured and compared. The obtained results show that the application of ultrasonic vibration can improve the machining accuracy considerably.