Papers by Keyword: Steel Ball

Abstract: Currently, there are several methods for indicating wear of the steel ball and screw shaft components of CNC machining centres. These include wear prediction of the steel ball and screw shaft of the ball screw by using the value of backlash. This value, generally, has to be determined using expensive equipment such as a laser interferometer or a ball bar. In order to reduce the monitoring cost of ball screw wear, especially steel ball wear, a new monitoring technique is introduced. This technique was developed from a correlation between steel ball wear and the surface roughness of the machined surface of a test piece. In this research, the balls were subjected to artificial wear which were achieved by using a barrel tumbling process. Experimental results indicated that ball wear causes increase in surface roughness of a machined test piece. Employing these results, an equation for estimating steel ball wear was developed. Research results also showed that this new technique can reduce monitoring cost significantly compared with the cost of conventional methods.

Abstract: The design of the optical fiber sensor system is used to detect the steel ball surface roughness and defects with displacement change such as cracks, pits, bumps and so on. Experiment results show that the sensor can distinguish between surfaces with different roughness. By establishment of the equivalent evaluation standard for surface quality, the system could detect whether the steel ball surface quality is qualified.

Abstract: Based on macro morphology, metallographic microstructure, field emission scanning electron microscope observations and microhardness testing, failure analysis of the GCr15 steel balls in the ball screw pair was dealt with in this paper. The experimental results showed that small scratches and pits were evenly distributed on the surface of the A steel ball which showed features of wear failure. Characteristics of the B steel ball surface morphology were contacted to fatigue failure. Microstructure observation on the cross-section of the B steel ball showed that martensite and carbides were uneven distributed which were caused by the uneven elements distribution in the raw materials. It was the main cause of this abnormal failure. Therefore, the quality of the raw materials needed to be strictly controlled and the reasonable heat treatment process should be adopted to ensure the quality of the steel balls.

Abstract: Toughness index is an important parameter of the quality of super-abrasive grits. In order to improve the design of the toughness index tester more reasonably and efficiently, we calculated the velocity of a steel ball in the capsule and simulated the impact process between the steel ball and the different capsule end faces with the ANSYS/LS-DYNA. The main results are as follows: (I) the maximum velocity of the ball is approximately 2.0106m/s. (II) with the increase of the curvature, the maximum value of normal stress declines while the effective area rises. (III) the maximum shear stress cannot cause diamond grits to break directly, but it can make small cracks and defects of the impacted grits propagate. These assertions are validated by the simulation which explains the experimental phenomenon well.

Abstract: At present, the steel ball surface defects are usually detected by manual work, but it has low efficiency and low reliability. For the current situation, in this paper, we design the steel ball deployment mechanism based on image processing technology, establish the mathematical model of the shooting point trajectory and determine the amount and location of the shooting points by the steel ball motion analysis. By the simulation based on Mathematica and Java, verify the effectiveness of the steel ball deployment mechanism in steel ball unfolding and defects recognition. Thus, the steel ball surface can be completely detected.

Abstract: In the detection of steel ball surface defects, the non-destructive eddy current testing has the advantage of reliability, high efficiency, non-contact and easy to automate, etc. Base on the establishment of the mathematical model of the ball surface unfolding, Correct processing of eddy current sensor output signal is the first conditions of accuracy. In the paper, base on the propose of unfolding mechanism of the ball's surface, with smooth, phase-sensitive detection, filtering and other methods to process the detected signal, so interference signals can be suppressed and to improve the signal to noise ratio; Then the signal can be further analyzed in time domain or frequency domain, the signal amplitude, frequency, phase and other characteristic quantities can be extracted, and the characteristic quantity of defect signal can be Calculated, So the surface quality of steel balls can be determined.

Abstract: The paper presents a fitness formula which is adopted to calculate the steel ball temperature uniform distribution time in the annealing process, analyses the steel ball temperature distribution in the process of heating. After the heat conduction equation of the steel ball is deduced, the spherical bessel function is adopted to solve it. The temperature distribution series solution is obtained. Using this formula, the steel ball temperature uniform distribution time of the different radius is calculated in the process of annealing. The result shows that the steel ball temperature uniform distribution time is the quadratic function of the steel ball radius. The time and radius data is adopted to deduce a second-order fitness polynomial. The steel ball temperature distribution is obtained in the different position. The steel ball temperature uniform distribution time is calculated by the fitness formula and the temperature distribution series one. The error between them is only 0.03%. The fitness formula can be used to calculate the steel ball temperature uniform distribution time. The change of the steel ball surface temperature is more severe than the internal. It often results in the crack of the steel ball in the annealing process.

Abstract: Wrinkling, wall thickness overthinning and cross-section distorting are main defects that seriously affect the forming quality of the tube in bending process. In this paper, numerical simulation based on PAM-STAMP 2G is conducted for the tube rotary-draw bending filled with steel balls as pressure transferring medium to analyze the deformation behaviors under various internal pressures. The results show that, tube bending filled with steel balls as pressure transferring medium can effectively restrain the defects of wrinkling and cross-section distorting. In addition, wrinkling and cross-section distorting of the bent tube decrease, the wall thickness thickening at the intrados of the bent tube decreases while the wall thickness thinning at the extrados increases with the internal pressure.

Abstract: Such evaluation standards as plumpness, roundness, force of cold upsetting, and the volume are made through the research on cold upsetting steel ball. Through a designed orthogonal test and the DEFORM simulation analysis, the process of ball billet is explained reasonably after primary selection and screening. Thus through comparison, it is seen that the original process is improved to a large degree.

Abstract: Surface quality of bearing ball is one of important factors to improve service performance. It is difficult to detect bearing ball surface defects with high precision and low cost by conventional methods. In this paper one new classification method based on optical fiber sensing technology was put forward from the longitudinal section angle. Inspection mechanism of Y-type and coaxial fiber sensor were analyzed, the mathematical models of the two fiber sensors were established and numerical simulations were realized by Matlab software. Influence of optical fiber parameters on light intensity modulation characteristic regulation was studied. Light intensity modulation characteristic experiments were done with specimens of different reflectivity and processing methods. The results show optical fiber sensing technique is an effective method to separate different surface of steel ball with extracting of two parameters displacement and surface reflectivity.