Papers by Author: Ming Hu

Abstract: This paper presents the kinematics for 3-PTT parallel machine tools, the kinematic is analytically performed, the forward and inverse position kinematic equations are explicit functions and workspace is derived and there is no singularity configuration and kinematic coupling in the whole workspace. The manipulability analytical of the parallel machine tool is investigated by the Jacobian matrix.

Abstract: This paper presents a new type of two 2-DOF Parallel 2PRR institution, with the unique advantages such as simple motion modeling and easy calculation of the positive and negative solution, operating a large space, simple structure and easy to control, etc. This parallel mechanism can not only be used for the development of glass cutting, grinding materials, milling, processing equipment, spare parts and other planes, but also can be used as a multi-DOF hybrid machine tool flat actuator parallel mechanism which can give full play the advantages of strong reconfiguration, with the main different combinations of auxiliary bodies and set up to meet the individual needs of the user reconfigurable manufacturing cell to be more complex parts processing and high-speed machining.

Abstract: It is necessary to develop drill point grinders in order to improve drilling quality and efficiency. In this paper, a new type of helical drill point grinder is presented. This grinder is mechanically simple, low cost and easy to be used. There are three axis simultaneous motions by means of two cams during helical drill point grinding process. Moreover, the relationships between the helical drill point parameters and helical grinding parameters are derived. As a result, the flank surfaces of helical drill points are described.

Abstract: The theoretical and experimental studies of statistical evaluation method for flatness error are conducted thoroughly, and evaluation parameters and corresponding practicable data processing model are provided. Furthermore, a large number of experiments have been done and statistical analysis has been conducted. The results show that the distribution of extract elements of almost 90 percent of the measured planes is accordant with censored normal distribution, which proves that statistical flatness error obeys normal distribution. The characteristic that sample points are random variables is taken full advantage of in the statistic method, and the flatness error can be calculated without the influence of gross error and therefore the rate of waste parts can be reduced effectively.

Abstract: A 3-DOF in-parallel machine tools based on a tripod mechanism is developed and studied, the kinematic is analytically performed, the workspace is derived, Analysis of the a number of conditions of the Jacobian matrix and manipulability is carried, The manipulability analytical of the parallel machine tool is investigated

Abstract: This paper takes one kind of 3-TPT Hybrid Machine Tools (HMT) as the object to study. It mainly analyzes the influence of the parallelogram mechanism as the restraining chain of machine on the posture error of movable platform. Firstly, on the basis of introducing the structure of HMT, the kinematics of the restraining chain of this machine is analyzed, and the kinematics equation of the restraining chain is established. Secondly, the influence of two kinds of factors including the shape error of parallelogram mechanism and the micro-rotation of Hooker joint around the axis of connecting rod is analyzed respectively, and the theoretical relationship expression is acquired between various errors influencing factor and the posture error of movable platform, thus the foundation for the theoretical error analysis of the HMT is laid.

Abstract: Grinding temperature is the main factor to limit the improvement of grinding efficiency. The main reason of grinding temperature rise is amount of heat transfer into the workpiece in grinding process. How to determine the proportion ratio, which heat transfers into the workpiece, is the main research issue to the precise machining scholars. In this paper, the heat resistance model is used to analyze the proportional coefficient about how much heat transfer into the grinding wheel, and the factors which to influence this coefficient are discussed. The moving heat source method is used to calculate the temperature field caused by single grain heat source, and the heat integral method is used to calculate the heat contains by the grinding chip, and then the heat proportional coefficients transferring into the chip and workpiece are determined respectively.

Abstract: This paper presents a new type of drill grinder based on a special universal joint. The special universal joint is composed of a parallel mechanism with three legs as the inputs. One can rotate as a spindle; other two legs can drive a moving platform and make a drill point get an accurate position in workspace. Due to the simple mechanical structure comparing the grinder with the existing conventional CNC cutting tool grinders, it should be easy for the grinder to manufacture at a low cost. In addition, inverse kinematic equations of the special type of universal joint are derived.

Abstract: In this paper, a new on-line diamond grinding wheel dresser, which is comprised of high-speed rotatory dressing wheel, micro-feed mechanism and control system, is presented. The principle of micro-feed machine working at requiring dressing depth, the control method of the dressing wheel speed adjusting and dressing depth, and structure of the control system are also introduced. The experiments we have done show that the dresser reach the goal of diamond grinding wheel on-line dressing.

Abstract: In this paper, a snagging parallel machine with 3-DOF is presented. It has the dominate merit in layout, structure, controlling manner and an attribute of large working space and easy real-time control. The machine tool achieves the anticipating effect and satisfies the need of the snagging operation.