Papers by Author: Xing Wei Sun

Abstract: The inner helicoid of the PDM’s stator is a kind of typical inner surface that is complex and tenuous. This paper studies the theory to form the inner helicoid in the screw stator which has a large lead and whose cross-section is composed by convex and concave curves using disc milling method. According to the varieties of the curve types of workpiece’s cross-section, a numerical method was proposed to calculate the theoretical contour shape of the disc milling cutter using coordinates of the fewer points on the workpiece’s cross-section. The manufacturing test confirmed the correctness of the design algorithm of the cutter’s profile and feasibility of this milling forming method.

Abstract: The key components of the single screw compressor are rotor screw and two star-wheels which are symmetrical arrangement. The rotor screw and two star-wheels have composed a special spatial meshing pair. The high meshed precision is the guarantee of its excellent performance. In this paper, we will study the milling technology of screw milling cutter to the rotor screw, and establish the finite element model of the cutter, and analyze the cutter’s stress situation during the milling process, make the cutting parameters of the screw optimization, In this paper, we will also study the influence of the Milling depth and cutting width to tool in displacement and stress, in order to provide a theoretical reference of selecting of appropriate cutting parameters ,improving of processing quality and reducing wear of the tool.

Abstract: The dynamic characteristics of machine tool is an important factor, which make affect on the cutting stability of machine tool. The poor dynamic characteristics will seriously affect the stability of cutting, make the low cutting efficiency and low machining precision, and also accelerate the wear of tools and even reduce the machine’s service life. So it is necessary to analyze the dynamic characteristics of machine tool, and according to the results of analysis to optimize structural parameters and motion parameters of the machine tools. This paper analyses the dynamic characteristics of machine bed and machined work piece of the CNC special machine tool for Kelly with the finite element software, and analysis of excitation characteristics of cutting tool. It also makes optimization design to the machine bed, through the analysis and optimization, the natural frequency and stiffness will be obviously improved. According to the structure and calculation of the motion parameters we can get the exciting force frequency to workpiece when it is cut, using interlocking tooth cutting method to replace the initial symmetrical cutting method in order to avoid the resonance produced in the cutting process and improve stability. The exciting frequency when cutting can be improved and the probability of resonance when cutting is lowered. All these ensure high efficiency and high stability cutting.

Abstract: The key parts are the stator and the rotor to realize the function of single screw hydro-mechanical. Along with the further improvement of performance requirement of mechanical product, it’s obvious that the general screw mechanical with rubber bushing stator can’t meet the requirement. So the process technology of inner helical curved surface with metal stator becomes the key technology to improve the screw mechanical property in the world. Considering the special structure of single-screw pump stator bush, a new method enveloping boring without instantaneous velocity center was presented in this paper. Based on motion principle of screw bush pairs and practical theory of enveloping boring without instantaneous velocity center, this method realizes the boring machining for inner spiral surface of stator on NC machine. In this paper, the motion regular pattern of screw in bush was studied, and the basic principle of enveloping boring without instantaneous velocity center was represented. In the end, the feasibility of this method was proved. The new method provides a theoretical basis for the machining of stator inner helical curved surface and the development of machine tool.

Abstract: According to the forming principle of equidistance curves, a mathematical model was concluded to calculate the curve contour of the cross section of the metal stator which has an inner helicoids and has an equal thickness rubber bushing using the primitive parameters of hypocycloid. By studying the cutting manufacturing technology of complex inner surface in slim parts, the feasibility of manufacturing large lead spiral inner surface by planning is studied and an NC envelop planning processing technology is proposed to manufacture the motor stator. The study of cutting simulation and cutting test provides the necessary theoretical support to the design of NC equipment and to cutting parameter optimization.

Abstract: The characteristic of servo system is an important data to influence the mechanical working properties of NC machine tool. In this paper, based on servo system characteristic, the cause of following error has been studied. It discussed the effect on machining precision of following error on part contour when machining circular contour. Then some calculation equations have been worked out. In order to reduce the following error, the method of compound control has been advanced in the last, and it has been proved to be a feasible way to reduce the influence of follow error on machining contour of NC machine tool.

Abstract: Along with the development and advance of science and technology, the quantity demanded of high technology and high performance mechanical equipment, such as screw pump, screw compressor, elastic and plastic extruder, steam turbine, blast engine and turbine, and so on, is great more and more in present society. And the requirement of performance is high more and more. The application of these products is widespread in many major industry fields of national economy, including military, petroleum, machinery, aviation, energy, chemical industry, elastic and plastic industry, etc.. The key part of these products is the rotor with special complex helical curved surface and leaf blade with particular slender curved surface. The machining level of them makes effect on the product performance and quality directly. In this paper, modern manufacturing technology, which makes use of tool nose’s NC trace of revolving disk milling cutter and whirlwind milling cutter to envelope milling slender curved surface by combined moving of several coordinate axes on special NC milling machine, was studied. The principle of the new technique was represented. The application instances are given in this paper.

Abstract: Conical screw rotor is the key part of conical double-screw extruder, with complex geometrical features, such as variable outside and inside diameter, unequal groove depth, varied head and lead. The manufacturing process is complicated and difficult. The precision and efficiency of conventional machining method is lower, the mating character of machined screw rotor is bad and the exchangeability is hard. On the basis of studying the geometric character and contacting process of double conical screw, this paper presents a new NC manufacturing method to envelope milling screw rotor with several axes moving combined. The automatic programming system for screw rotor NC machining is developed. This research increases the machining level of conical double screw. It has conspicuous engineering meaning.