Applied Mechanics and Materials Vols. 37-38

Abstract: To analyze the lubricating state and the heating performances of the spindle bearings in ultra-high speed electric spindles, taken the characteristics of oil-air lubrication into account and based on the theories about rolling bearing dynamics and thermal elasto-hydrodynamic lubrication in point contact state, a model was built with the energy method for analyzing the heating performances the ball elements on both raceways in spindle bearings. An equation was derived for calculating the total quality of heat produced in a bearing. The influences of some basic factors such as the running speed, the axial preload, the oil viscidity, the design contact angle of bearing, and the ball materials and so on are analyzed on the heating performances in a bearing. The results show that it is easy to come into being elasto-hydrodynamic lubrication state for a bearing running in an ultra high-speed and lubricated by oil-air. It is also shown that the higher speed is, the more the quality of heat produced inside the oil films in the elasto-hydrodynamic lubrication state will be, which will bring the bearings working conditions worse.

Abstract: . Determining axial movement displacement is a key question for designing the die which is used to form asymmetric shaft parts by CWR. FE model is established in this paper, the rule of process parameters influence on axial movement displacement is also analyzed, and then influence factors on axial movement displacement are gotten. The rule is that forming angle, spreading angle and area reduction have effect on axial movement displacement; rolling temperature and the diameter of rolled part has no effect on it. The conclusion provides the foundation for further determining axial movement displacement accurately.

Abstract: This paper introduced some current researches on the corner error in WEDM and put forward the factors that have an influence on the corner error. The deflection of the wire-electrode that has been caused by discharge force, feeding directions of the wire-electrode and radial flops of the guide pulley was analyzed in detail. To minimize corner errors, the energy control strategy and the trace control strategy are presented. Especially in WEDM-HS processing, the methods improving the processing precision are given as follows: Using the over-cutting and retract program, controlling the wire-electrode tension and improving the guiding and allocation parts.

Abstract: With times of ecological civilization coming, Green design is becoming a new horizon of modern furniture innovation and development. This study explored the strategies, methods and procedure of modern furniture green design, and described the framework of implementation. The procedure model of modern furniture green design were also analyzed and built.

Abstract: This work presents a workspace solving approach for a tomato harvesting manipulator with seven degrees of freedom (7 DOF) based on a special envelope method. In this method, the joints of the manipulator was categoried into two groups, and the workspace boundary of each group was formulated according to the envelope equation by MATLAB and AutoCAD by considering the joint limits. To analyze the reachable and dexterous workspace, the position and orientation of the last link was plotted. The results show that the width and height of the wrist workspace of the tomato harvesting manipulator are 1.5 and 1.2m respectively, which can satisfy the tomato picking requirements. The reachable workspace and the dexterous workspace are affected by the length of the last link and the end-effector. In order to minimize the hollow in the workspace, it is necessary to choose the rational length of the 5th link and the 3rd link and the angle range of the 5th joint. The algorithm can make the workspace visualized and be applicable to all practical manipulator configurations.

Abstract: Headstock is a key component of gear milling machine. The dynamic functional performance of the headstock is usually influenced by uncertainties of both geometric and non-geometric design parameters. A new mathematical model to represent relationships among first frequency and design parameters of the headstock were derived with Rayleigh method. Then, a larger-the-better and smaller-the-better robust analysis and optimization model was developed. The sensitivity analysis results show that height of the headstock makes a great impact on the first frequency. Through robust optimizations, the first frequency is scaled up by 3.35 percent while minimizing the variance of the first frequency.

Abstract: The key technology of the liquid core heavy reduction rolling mill relates to the roller’s normal life cycle in a bad work condition. It is the guarantee of continuous production. This paper simulated and calculated the two roller types which are built-up welding roller and roll-sleeve type roller, material of the rollers is H13 (4Cr5MoV1Si) which has better synthetical mechanical properties. It also calculated the fatigue life under the steady temperature, stress and strain fields after rolling for five cycles though the strain-life method.

Abstract: Micro-milling is widely used in material removal processes in industry. However, burrs are often formed on workpiece edges in milling process. Burr effects the dimensional tolerance and performance of the workpiece seriously and is desirable to be controlled. Burrs prediction technology is useful for cutting conditions optimization to control burrs forming. Due to lots of factors influencing the formation process of burr, it is a difficult task to establish the burr size prediction model by mathematical and mechanical method. RBF neural network was used for burr formation predition. Design of the network, network structure parameters determination and generalization capability of the network were analyzed and discussed. Achieved network has good fitting performance and generalization capability validated by experiments.

Abstract: A direct temperature control method for electric heating dryers was proposed in order to obtain satisfactory control effect. The controller of analog compound orthogonal neural network used a direct adaptive control method. Simulation results show that this controller has higher speed performance and smaller overshoot than a PID controller. It is suitable for the control of uncertain objects and provides a novel approach for the control of uncertain systems.

Abstract: Based on the simple crack model and the finite element method (FEM) theorem, the corresponding dynamic equation of the cracked rotor based on FEM analysis is modeled and the numerical simulation solutions are obtained. By analyzing the dynamic characteristics of cracked rotor in diverse conditions, the properties of the un-cracked rotor and cracked rotor are discussed. A valid fault diagnosis method of cracked rotor is purposed. The method demonstrates that the cracked rotor can be identified by estimating if the swing of disk center obviously accretion and appear wave crest when rotate speed is a half critical speed of rotor shaft system.