Papers by Author: Jun Gong

Abstract: 0-20wt.% PEEK reinforced PTFE composites were prepared by a cold pressing-sintering method. The tribological properties and surface morphology of the transfer films were investigated via a MRH-3 friction and wear testing machine and scanning electron microscopy (SEM) respectively. Results show that the wear resistance of PTFE composite is improved more than 670 times with the addition of 20wt.% PEEK and the lowest friction coefficient is obtained with 5wt.% PEEK. Surface morphology shows that the transfer film formed on the counterface becomes more and more uniform and continuous with the addition of PEEK filler, frictional trace on the transfer film suggests that abrasive wear occurred during the sliding process.

Abstract: The problem about friction and wear characteristics of piston ring which is directly related to the sealing properties of stirling engine was analyzed. An improved seal structure of piston ring was taken as the research object, the influence of the temperature and the pressure of refrigerant were considered when the friction and wear characteristics of piston ring in stirling engine was studied. The calculation formula about radial weal amount of the piston ring with the change of the temperature and the gas pressure was derived by using the peeling wear theory. Then, the experiment was taken to confirm these formulas. The results show that the formulas were right. Hence, a viable way to analysis the sealing properties and life prediction method of piston rings was got.

Abstract: This paper mainly researches the control system of honing machine spindle reciprocating motion. On the basis of brief introduction to the processing of honing machines, its mathematic models were established, and design the double control system on the base of fuzzy control .Two fuzzy controllers were used separately according to actual error signal of the system output to improve the system rapidity and overshot .so that make the designed control system of honing machines spindle reciprocating motion can satisfy the design requirements better. Finally the control system was conducted by using the tool of MATLAB. The simulation result showed that the double fuzzy controller can effectively reduce steady-state error of the system and overshoots can well satisfied the system performance index, and has some quick response ability.

Abstract: The regenerator of Stirling refrigerator is normally installed a contact sliding sealing ring, but if the sliding sealing ring working hour is overlong, it would cause wear heavily, and reduce the service life. This paper focus on resolving this problem: use a clearance seal device, which without leakage under the high pressure test, instead of the sliding sealing device. Meanwhile, use the clearance seal device would eliminate contact wear which would cause the leakage losses. Therefore it is fairly important to establish a theoretical model to imitate leakage process in the clearance seal device, analyze the factors which influence clearance seal, and find a solution to improve clearance seal in Stirling refrigerator.

Abstract: As the improvement of honing velocity, acceleration and accuracy, corresponding requirements about control technology are put forward to meet the improvement of high machining efficiency. While the honing machine spindle reciprocating reversing control is the key control link, directly affects the ability of the machine abilities and quality. Aim at the traditional honing machine reciprocating motion cannot satisfy the requirement of high speed, high acceleration and high reversing accuracy. According to the characteristics of honing machine mechanism of reciprocating movement, establish its mathematic model and the system of fuzzy and PID double control model, and then the control system was conducted by using the tool of Simulink. The simulation result showed that using fuzzy and PID double control can make overshoots reduced compared with conventional single fuzzy control and PID control, and can well satisfied the system performance index.

Abstract: This paper introduces a new, visualized approach for including all the geometric feature variations in the tolerance analysis of mechanical assemblies. It focuses on how to characterize geometric feature variations in vector-loop-based assembly tolerance models. The characterization will be used to help combine the effects of all variations within an assembly in order to perform tolerance analysis of mechanical assemblies by employing commercial 3D kinematic software (e.g. ADAMS). Equivalent variational modeling, based on TAKS method, has been developed for modeling variations in 3D mechanical assemblies. Create a library of Equivalent Variational Joints (EVJs) to allow inclusion all kinds of variations in analysis, and allow the kinematic model to include both geometric and dimensional variation in a velocity analysis. EVJ, for use in tolerance analysis, was developed for commonly used 3D kinematic joint types, and was implemented with examples to explain their use to form Equivalent Variational Mechanisms (EVMs).

Abstract: We attempt to resolve the spray trajectory planning efficiency and the coating thickness uniformity for big curvature surface on complex curved surfaces. The least square method was proposed for spray partition of complex curved surface based on topology partition. First, the big curvature surface was extracted from complex curved surfaces. Then, the big curvature surface was fitted into the natural quadric surface based on least square method and the fitting algorithm was given. Simulation results show that, the fitting algorithm is feasible, and this method can effectively reduce the number of patches, which can improve the spray trajectory planning efficiency and the coating thickness uniformity.

Abstract: The article focused on the design of milling cutter for machining helical curved surfaces. First, the characteristics of 3th generation profile in screw compressor were presented; then the equation of touch line between milling cutter and workpiece was constituted based on the envelop principle from milling cutter rolling surface and spiral curved surface; and elementary theories and methods were put forward for designing contour of milling cutter in machining spiral curved surfaces, finally the calculate equation was validated through the machining example by Matlab.

Abstract: We attempt to resolve the spraying trajectory planning efficiency and the thickness uniformity problems for big curvature conical surface in complex curved surfaces. By experimental data, the coating growth rate model is obtained and we analyzed the applications of the model on conical surface. Based on the characteristics of conical surface is the regular surfaces, we planned the spray gun trajectory on this surface, and used the methods of adjust the spray radius and track section to discussed the calculation method of the coating thickness and optimization of correlation parameter. Taking car bumper for example, we studied the spray trajectory optimization on the juncture of conical surface and plane. Simulation results show that, our method can effectively increase the efficiency of spray trajectory planning under the premise of ensuring the thickness uniformity, the spray velocity show the non-linear variations with spacing distance and others show the linear variations, the uniformity of coating thickness meets the quality request on the juncture of conical surface and plane.

Abstract: A comprehensive tolerancing system is presented with its design principle, system architecture and key functions. The following functional modules, automatic generation of dimension chain, equivalent variational mechanism (EVM) modeling and visualized 3D tolerance analysis, are described in detail. Design intent is expressed by assembly tolerance specifications, which may be added to the model and used in computing predicted quality levels. A comprehensive method, based on equivalent replacement, has been developed for modeling variations in 3D mechanical assemblies. The models are constructed of common engineering elements: dimension chain, kinematic joints, assembly datums, dimensional and geometric feature tolerances, and assembly tolerance limits. The method is consistent with engineering design practice and is well suited for integration with commercial CAD systems. To make the tolerancing system robust and efficient, new functionalities are added to well-known CAD software and simulation environment. Tested by many samples, this system shows good robustness and practicability.