Papers by Keyword: Ball

Abstract: Cyclic pressure fatigue tests of silicon nitride ball were performed in two phases. In the first phase, compressive and tensile stresses were applied to two cracks on the ball surface, respectively. In the second phase, tensile stress was applied to the crack that was applied to compressive stress in the first phase to grow. The effect of cyclic compressive stress on crack growth was investigated through this series of tests. The results are as follows. The ball did not fracture in either Phase 1 or Phase 2 tests. The crack did not propagate when the maximum compressive load of approximately 5 kN was repeatedly applied across the crack surface. In addition, the crack applied with compressive stress before tensile stress, and the crack which was not, both grew to about 520 μm during N ranging from 0 to 1.2×10⁷ fatigue cycles. The crack applied with compressive stress before tensile stress at fatigue cycles N = 10³ grew about 170 μm longer than the crack to which stress was not applied.

Abstract: In order to investigate the effect of pre-crack lengths on strength of silicon nitride balls under cyclic pressure loads, growth behavior of 600~700μm pre-cracks were compared to those of 200μm~300μm and 400~500μm pre-cracks. Furthermore, the change in initial threshold limit of the maximum stress intensity factor was discussed. It was found that the increasing ratio of stress intensity factor during N=0 and N=1000 distinguished the failure and non-failure, and pre-crack length had strong effect on the threshold limits of the increasing ratio.

Abstract: In order to investigate the effect of pre-crack lengths on silicon nitride balls under cyclic pressure loads, the pre-crack lengths ranging from 400μm to 500μm were observed. Their growth behavior was compared to that of 200μm to 300μm pre-cracks. Furthermore, the initial threshold limits of their maximum stress intensity factors were measured.

Abstract: This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text. In this paper, the motion of the ball and beam system based on periodic input is studied, the chaos of the system is discussed , and the relationship of the chaos and the input parameters is analyzed . on the premise of avoiding chaos, the trajectory motion law of points with suitable oscillation parameters is studied in the poincare cross-sectional view. And the swing-up control law of ball and beam system is submitted, it consists of such three parts: increasing the range of swing , adjustment and maintain constant swing .Finally, the simulations result is given to verify the efficiency of control law.

Abstract: This paper reviews principle and characteristics of the tennis serving machine and the tennis picking machine on the market. According to the actual situation, it intends to design a new type of tennis equipment for the tennis practitioners, which is named intelligent tennis vehicle. This machine consists of ball-storage mechanism, supply mechanism, serving mechanism, picking mechanism, frame and control circuit. This machine uses storage battery for the power supply, and it uses MCU (micro controller unit) as the controller, controlling all kinds of the mechanisms. It can help people to practice tennis, and pick up the large number of scattered tennis balls conveniently. This machine can meet the needs of different requirements, so that practitioners can better improve the tennis technology in order to achieve the purpose of fitness and training.

Abstract: This paper proposes a novel method for machining ceramic balls by centerless grinding technique performed on a surface grinder. In this method, a compact unit consisting mainly of an ultrasonic shoe, an ultrasonic regulator, a relay controller, a blade, a stopper and their respective holders is installed on the worktable of a surface grinder to conduct centerless grinding operations of ceramic balls. The ultrasonic shoe and regulator are produced by bonding a piezoelectric ceramic device (PZT) onto a metal elastic body, and when two phases of AC voltage are applied to the PZT an elliptic motion occurs on their end-faces which can be used to control the ball rotational motion in the radial and axial direction of the wheel, respectively. The function of the relay controller is to regulate the alternating current “on” and “off” time which is applied on the regulator for achieving the whole spherical surface grinding process. A grinding unit was actually constructed and it was experimentally confirmed that the ball rotational speed can be controlled well by the shoe or regulator. Grinding tests were subsequently carried out and the obtained results indicated that the constructed grinding unit performed well on actual ball centerless grinding operations.

Abstract: According to the structure and its transmission principle of the cycloid ball planetary drive, a thermo-mechanical coupling analysis model of non-backlash cycloid ball engagement pair is developed in this paper. The force formula is derived by using hyperstatic method. Using finite element analysis, the variation of thermo-mechanical coupling contact stress of engagement pair at maximum force position with working temperature has been obtained. The results show that maximum coupling contact stress is located at the load transfer contact points between the ball and the cycloid grooves, and it increases significantly with the increase of temperature. The results obtained offer important theoretical basses for research on reliability of precision cycloid ball engagement pair and design of non-backlash transmission performance.

Abstract: A torsional dynamic model of the cycloid ball planetary transmission system is established with considering the direction changing of engagement force and the multi-balls engagement in transmission process. By analyzing the position relationships of each engagement force and the displacement relationships of each component, the governing differential equations of system as well as the dimensionless equivalent engagement rigidities of each transmission disc are derived, and the frequency spectrum of the engagement rigidity excitation is present. The results show that the cycloid ball planetary transmission system is a parametric vibration system. The engagement rigidity excitation between the center disc and the planetary disc is a periodic and time-variant function, and the high-order harmonic components are included in the frequency spectrum.

Abstract: The roller Hourgrass worm transmission has the properties of high efficiency in meshing, high power transmission, large load capability, long working live, and can save nonferrous metal. This paper made deep investigation into the precision conjugate theory for the roller Hourgrass worm transmission. And the forming theory and machining of the worm gear and its cutting tool,---the hob of worm gear, has been researched as well.

Abstract: The precision and efficiency of lapping for balls are determined by the lapping uniformity. One method of evaluating the ball lapping uniformity for different lapping mode is proposed, which is based on kinematics analysis under the assumption of pure rolling. Lapping experiments of V-groove lapping mode, dual rotating plates (DRP) lapping mode, and dual-rotating eccentric V-groove (DREVG) lapping mode are carried out on steel balls, and the lapping traces are observed. The prediction of the evaluating method is in accordance with the experimental results.