Papers by Author: Jia Long Ren

Abstract: The impact of friction factor, thickness of the cold extrusion, semi-cone angle and other factors on cold extrusion was analyzed. Various process parameters were set and optimized. Cold extrusion process of hollow pieces was simulated by DEFORM-3D software. Through the simulation of the virtual velocity field, strain field, stress field, load - stroke curve and metal deformation process, the flow velocity of the metal and the deformation of the workpiece were studied. The metal flow routes and the parts that are easy to wear in die were gained. The above research results provide valuable references for the processing of hollow pieces.

Abstract: For solving the crack in crankshaft, laser cladding remanufacturing was involved. There were three key points about laser cladding remanufacturing discussed in this paper.The three key points included process flow , process environment and laser cladding materials selection . Using the ANSYS analysis software, the simulated analysis of the temperature field , stress field and the residual stress of the three kinds of cladding layer have been carried on, the best cladding materials for single-throw crankshaft crack of base material 45# is determined by studying the repaired results about Iron-based,Cobalt-based,Nickel-based self-fluxing alloy powder cladding materials.

Abstract: To explore the influence of the water vapor cooling conditions on grinding temperature field of titanium alloy TC4 material, ANSYS simulation and test methods are adopted in this paper. Simulation and experimental studies show that: water vapor as coolant can reduce the surface temperature of the workpiece quickly by changing the wheel speed, workpiece speed and cutting depth; Water vapor cooling can control the grinding zone temperature below 400 °C on certain conditions, and compared with dry grinding it can reduce more than 50%; The grinding zone temperature can significantly be reduced by optimizing the grinding process parameters and improving the quality of the machined surface.

Abstract: The chemical composition and properties of nickel-based superalloy Inconel 718 was investigated first. Turning Inconel 718 was simulated by Deform-3D software to figure out main affection factors, and optimal combination of cutting speed, feed rate and cutting depth was introduced. In addition, different cooling and Lubrication methods (heat transfer coefficient f of cooling and tool-chip friction factors) for cutting of Inconel 718 was studied, and a best cooling/lub mode was obtained.

Abstract: Based on the pool film boiling, the paper discusses the heat transfer coefficient of fogdrop jet into cutting zone to cool high temperature wall and then founds the model. It can be concluded by transient test in cryogenic pneumatic mist jet cooling high temperature titanium surface with different water flow, that when reaching the best cooling effect, the water flow of cryogenic pneumatic mist jet cooling as well as the materials vaporizing and involving phase change heat-transfer under certain temperature must be equivalent, and at that time, the heat transfer coefficient of cryogenic pneumatic mist jet cooling will reach the maximum.

Abstract: Cold air cutting is a kind of environmetnally friendly cutting technology. The present study investigated the influence of cold air and cold air with oil mist on cutting temperature, cutting force and tool wear in the machining of Cr12 tool steel. For comparision, dry and flood coolant was also used as the cooling/lubrication conditions in the experiments. The findings of the study show that cold air with oil mist was the most effective cooling/lubrication condition in reducing the cutting temperature, cutting force and tool wear during the machining of Cr12 tool steel.

Abstract: Enhancing the cooling to spread heat in the process of the material cutting and milling has positive effect on increasing the efficiency of cutting and milling and assuring the apparent mass of test sample cut and milled. Basing on the experiment about the mixture of fixed pressure, fixed air and different quantity of water atomizing jet cooling the Ti alloy, this article discusses performance and regulation of phase transformation heat—transfer of simulating grinding Ti alloy forced air cooling by the mixture of fixed pressure, fixed air and little water.