Papers by Author: Yu Jun Cai

Abstract: Since the 21st century, the development of automotive and home appliance industries has greatly contributed to the prosperity of the plastics industry, which has led to an increasing demand for molding molds. In the production process, the molds will be impacted, worn and corroded, especially in the production of plastic products made of PVC, fluoroplastics and flame retardant ABS, etc. The molds will be corroded by the corrosive gases generated such as hydrogen chloride, hydrogen fluoride and sulfur dioxide, which requires plastic molds to have a certain degree of corrosion resistance while ensuring strong toughness.S136 SUP is a modified martensitic stainless steel based on S136 from ASSAB, Sweden, which has fine-tuned the content ratio of some elements to ensure a certain strength and high toughness at the same time. The chemical composition, heat treatment and microstructure of the steel have a certain influence on its corrosion resistance, and the tempering temperature of the heat treatment has a greater influence on the corrosion resistance of martensitic stainless steel. Therefore, in this paper, the microstructure and corrosion resistance of S136 SUP at different tempering temperatures are explored and studied.

Abstract: In view of the cooling difficulty in complex injection mold, the difference between conventional cooling channels and Conformal Cooling Channels (CCC) is researched. CCC is superior to conventional cooling channels on cooling effect according to the simulation analysis of plastic flow based on Autodesk Moldflow Insight software. Considered the manufacturing difficulty of CCC, an approach which uses three-dimensional printing and investment casting is put forward in the end.

Abstract: Under the condition of cutting speed 10-300m/min, rake angle -10°、0°、10°and cutting depths 0.05mm、0.1mm and 0.2mm, the experiment study of adiabatic shear serrated chip and surface roughness are carried out. The influence of cutting condition on serrated chip is analyzed through the metallographic observation of obtained chip. By the measurement of finished surface, the influenc of cutting condition and adiabatic shear on surface roughness is also investigated. The rusults show that the reason lead to serrated chip in high speed cutting of Ti6Al4V is adiabatic shear, not the periodic fracture.The adiabatic shear serrated chip is easier appear and the degree of segment is more large under the condition of higher cutting speed, larger cutting depth and smaller rake angle. The surface roughness is smaller when the cutting speed is higher, cutting depth is larger, and rake angle is smaller.

Abstract: This article states the error factors in parts of data acquisition and data processing of reverse engineering, and gives optimization suggestions in practical applications. It provides a more practical method for manufacturing products closer to the samples.

Abstract: In this paper, a very detailed process analysis for UAV integral impeller was made. According to the specific processing requirements, the appropriate CNC machine, blank and cutting tools have been choosing. In the rough machining process, various machining strategies have been used for comparing and analyzing, finally a more efficient roughing method with the accurate machining parameters will be obtained. At the same time the machining method have been improved and the processing parameters also have been determined in the semi-finishing process. Through the simulation processing in VERICUT, the possibility of the existence of interference which is usually occurred in the actual processing can be ruled out and the program optimization will be finished in the meantime. Finally, using intelligent three-coordinate measuring machine the consequence will be verified and inspected in the actual machining process.

Abstract: A method for building the constitutive relationship based on the J-C model and hardness is presented through considering the influence of hardness on the yield strength and the tensile strength. A constitutive relationship of hardened AISI 1045 is built by this method and the adiabatic shear critical cutting conditions of three kinds of hardness AISI 1045 steel are prediction through a model building by the linear pertubation analysis which considering the influence of compression stress of the primary shear zone, the cutting conditions and the constitutive relationship. For proving the prediction results, some orthogonal cutting experiments are performed to get the critical cutting conditions of adiabatic shear. The comparison shows that the prediction results are consistent with that of experiments.

Abstract: The ultimate goal of the metal forming industry is to form components made of a specific material into a required shape without experiencing wrinkling, bifurcation and spring-back. This study is devoted to develop the whole process by making rules of precision for specific part geometry. For inner clutch shell a computer simulation system and the general procedure of dynamic simulation in sheet metal forming are presented. Finally compute all simulation results with reference to the original part property and recommend the appropriate process flow to produce the part, the comparison with tryout results shows that the formality simulation of thick panel with precise die face is reliable and accurate.

Abstract: Orthogonal cutting experiments of hardness AISI1045 steel( HRC45) are performed. The change of chip formation and cutting force with cutting conditions are investigated through metallurgical observation, and the critical cutting speed of adiabatic shear of AISI1045 steel at different cutting depths and rake angles are given. In addition, the saw-frequency and space length of serrated chip and the influence of serrated chip on cutting force are also studied. The critical cutting speed decreases with the increase of cutting depth, but increases with the increase of rake angle. The saw-frequency of serrated chip is found to be independent of the cutting depth, and increases with the increase of cutting speed and rake angle. The cutting force decreases with the increase of cutting speed and rake angle, but increases with the increase of cutting depth, and there isn’t a sudden change of cutting force at the onset of adiabatic shear.

Abstract: In order to enhance the processing efficency of complex cavity surfaces by using iso-scallop height method, a subdivision method based on the improved image direction information measure is proposed in this paper. According to the relationship between maximum cutting bandwidth and cutting direction in the theory of iso-scallop height, the method constructed an optimal cutting direction angle field image in the u-v system of parameters firstly; and then an improved direction information measure definition which combined with the characters of the angle field image was proposed; Finally, the subdivision boundary for mold cavity surface was identified by using the direction measure as the edge characteristic index. Experimental results indicate that the proposed method demonstrates good performance in distinguishing and extracting boundary points of surface subdivision.

Abstract: This paper proposes an efficient method to the lowest cost tool sequence for semi-finishing of mold cavity on a 3-axis mill machine. Suppose that the rough machining has completed, so the redundant slice is thin enough and can be removed with a single pass of the semi-finishing cutter. To guarantee the cutting operations do not gouge the desired surface, there is a largest cutter which can be used at any part of the surface. On the other hand, to improve efficiency, large cutter should be priority selected. Dynamic programming finds a near optimal tool sequence based on the approximate evaluation of machining cost.