Research On The Steel Ball Surface Defects Inspection Technology

The rolling bearing is known as “industrial joints”in the national economy and the steel ball is the most commonly used rolling element bearing the load and transmitting the force. The quality of the steel ball plays a key role in the bearing precision, the dynamic performance and it's service life. According to related statistics both at home and abroad, 71.4% of the ball bearing vibration and noise is caused by the steel ball's surface defects and it's the mainly factor to restrict the improvement of the ball bearing quality. The steel ball surface defect detection is the last process of the quality inspection level during the steel ball production and also the key working procedure to decided the precision of the steel ball. Thus, steel ball surface defect detection is the key factors to influence the steel ball quality improvement. At present, most of the steel ball factories in China use the automatic steel ball quality detection device mainly depending on imports. But the equipment is too expensive to go into operation in the steel enterprises of our country. Most of the domestic scholars studying the automatic steel ball quality detection device are still in the experimental stage. Small successful prototype also needs to improve the test efficiency and accuracy. Therefore, China urgently needs to develop a automatic steel ball quality detection device, which has a moderate price, high sensitivity and good quality to break the developed countries monopoly on high precision steel ball and bearing market.In this paper, the research on the steel ball surface quality automatic detection is under a series of project funds, which is based on the coaxial optical fiber sensor of RIM-FOS to realize it's function. The Beckmann scattering theory and double beam comparative measurement method is assumed as theoretical basis. Apply the optical fiber sensing technology and weak signal processing method to the steel ball surface quality detection, based on the single-chip system of STM32 and PC system, strive to develop a set of steel ball surface quality automatic detection device, which has a moderate price, high-speed and efficient, to make up the “short board” in high precision bearing industry of our country.This paper quantitative the parameters of steel ball surface defect, combined with the steel ball surface defect evaluation criteria of machinery industry. We divide the defects into rough defects and displacement defects, using the optical fiber sensor to extract the defect information; It's based on the Beckmann scattering theory and double beam comparative measurement method to extract the displacement defects and the surface rough defects information of steel ball. Analyze the working principle of RIM- FOS and the design of the optical fiber's structural, choose three times of coaxial optical fiber of RIM- FOS to test the steel ball surface quality. Analyze the transmitting fiber of the emitted light intensity distribution assumption, using the gaussian distribution assumption, according to the geometry relationship of the spherical model to derive the function model of optical fiber sensor, lay a foundation for calibrating the optical fiber sensing system.Analyze and design the hardware system and software system of steel ball surface defect detection. The design of the hardware system includes the design of signal processing system and the single chip microcomputer system. Design the signal processing circuit to complete the photoelectric conversion and through differential amplifier circuit, band-pass filtering amplifying circuit and low pass filtering amplifying circuit to filter the noise and enlarge the useful signal step by step. Extract the characteristics of the displacement defects through the design of division circuit, which reflects the surface defects information of the object under test. The single-chip system adopts modular design through the design of the module: A/D conversion modular, serial communication modular, data storage modular, etc. Using C language programming to realize the modulus conversion and send the collected signal to the PC for analysis.In this paper, we prepared for the experiment by making circuit boards and setting up experimental platform. Complete the calibration of displacement and roughness of the optical fiber sensing system by measuring roughness of the standard specimen test. Do multiple repetitive tests about the roughness and displacement of the ball surface defects based on a large number of the known defects. Initial establish the correspondence between waveform of the analog voltage output and defects type of the ball surface. It lays a foundation for the automatic monitoring equipment development of the ball surface quality.