Papers by Author: Zhao Jun Yang

Abstract: There is often more than one failure at the same time when NC machine tools fails, but only one failure data is recorded which leads to that the reliability model of NC machine tools is not rational. In addition, the assumption of “repaired as good as new” for NC machine tools which consists of hydraulic, mechanic and other complicated subsystems is questionable and unreasonable. In this paper a method of reliability modeling using Blocksim and Weibull++ for NC machine tools is proposed. In the end, one example is provided and examined to show its potential applications and benefits. The result shows that the method of reliability modeling is more scientific and more in line with the practice.

Abstract: Based on the deeply study on VERICUT, the generating process of spiral bevel gear surface is simulated in this paper. A certain surface generation process of spiral bevel gear is analyzed as an example. First the 3D solid models of gear cutting machine, cutter and gear blank are built. Then the NC program is compiled based on the generating principle of tooth surface. Finally the surface generating movement of spiral bevel gear is realized through selecting control system and importing the NC program. It can be indicated that the simulation analysis of surface generation can optimize the cutting movement and provide theoretical basis for the movement analysis of gear cutting.

Abstract: Skew bevel gears are fundamental element of transmission system. Processing quality of skew bevel gears has impact on the performance of system. An accurate processing method of tooth surface of skew bevel gears with spherical involute is proposed. According to the space meshing theory, the meshing equation of skew bevel gears is built by the theory of coordinate transform. And the generating principle of generation line of tooth surface about skew bevel gears is studied. In terms of the formation theory of tooth surface, moving process model of milling processing is established. And the generation line is as chord of face circular cutters to cut the tooth surface. Machining of the profile of skew bevel gears is performed using three axes linkage by the method. Finally, the transmission experiment proves that this method can improve dynamics and strength characteristics.

Abstract: Through the plentiful authentic early failure data collected by field tracing test of 30 CNC machining tools with ATC (Automatic Tool Changer), we searched for the rules and distribution of early failure of the CNC machining tools. Main fault mode and facts which usually make a great possible impact on the reliability of these products are identified based on an analysis of these early failure data. The distribution model of early failure is found by analyzing and processing these data with the method of regression analysis and hypothesis testing as well as Bayesian forecasting of early fault phenomena. Suggestions how to enhance reliability level of these products are proposed.

Abstract: Based on the the principle of generating line of spiral bevel gears, a new modeling method about spiral bevel gears is proposed. Mathematical pattern of spiral bevel gears with spherical involute is developed about two parameters. A kind of simulation modeling software of spiral bevel gears with spherical involute is developed in matlab-guide environment. The data of tooth-surface are collected and calculated in the simulation system according to the machining parameters of a pair of gears which are established. It is convenient to establish accurate solid models of spiral bevel gear by obtained data points. Thus it can provide a feasible and effective way for CAD/CAE modeling and is modeled perfectly in computer so as to simulate the platform of virtual manufacture and meshing analysis.

Abstract: Improving the reliability of linear motor is one of the best ways to improve its quality and performances. The core in reliability test is to simulate the dynamic loading as real operating condition. In this paper, a common loading model, which can reflect various operating conditions of linear motor, is proposed. Then a set of dynamic loading method for reproducing the operating conditions is put forward. This method completes dynamic loading against linear motor simutaneously in its moving and non-moving directions using servo control contact method and magnetic non-contact method, respectively. This research provides not only a set of feasible method for linear motor reliability test in lab, but also a prerequisity for studying linear motor reliability further.

Abstract: In order to manage equipment maintenance work and reduce enterprise cost, a new prediction method of reliability parameters is proposed based on failure time in this paper. The reliability model was built based on failure time, and the reliability parameters were obtained by the empirical modeling method. Then parameters from historical data were used as predictive model parameters, which applied the exponential smoothing methods to establish predictive models based on historical data. Finally, prediction model of reliability was built by the predicted parameters used the above method. With failure data of CNC machine tool as an example, analysis of living example indicated that the proposed method acted effectively, and the precision of prediction is quite ideal, which help consumers of CNC machine tool provide the decision support of equipment maintenance management; meanwhile, strengthen the enterprise's competitive power to some extent.

Abstract: By using the information entropy theory, a solution to Weibull-small sample prior distribution of system reliability is proposed, which aims at solving the reliability estimation of high-end CNC. Firstly, the prior information is converted from subsystem level into system level based on entropy theory. Then, the prior distribution is solved with the constrained maximum entropy method. Finally, multi-information is fused based on the entropy weighs. It is proved by a case example that this method can obtained the prior distribution under Webull-small sample effectively.

Abstract: By analyzing the structure features and tool changing process of a large-scale national Automatic Tool Changer (ATC) with a chain-type tool magazine, a chain-type tool magazine reliability test bench is designed with a new fault detection system, where a new failure data collecting method is applied for taking failure data statistics and reliability analysis. This set of fault detecting and reliability analyzing system not only provides a way for ATC to predict system faults, but also creates good conditions for further ATC reliability research.

Abstract: The purpose of this paper is to present a novel device for measuring draw and plug forces, which is composed chiefly of a pull stud, a top modified tool shank, a middle modified tool shank, a down modified tool shank, and an end cover. The modified tool shank structure is proposed, and the working principle of the device for measuring draw and plug forces is demonstrated. Also, the data conversion and memory module and the circuit principle are investigated.