Reliability Analysis And Software Development For Universal Milling Head Key Component Of High-speed Working Center With Five Axis

The spindle is one of the key components for universal milling head of high-speed working center with five-axis. The reliability index of the spindle directly determines the processing level of universal milling head, also can affect the machining accuracy. With the continuous improvement of technology, to produce a higher precision, higher strength, less vibration, less deformation and lower noise of universal milling head has become a trend. So it is great significance for analyzing and researching reliability of the spindle. In this paper, taking the spindle of a GMC2000A’s universal milling head as the research object, expand research and analysis by the reliability theory. The main work is as follows:(1) At first, establish the spindle finite element model according to the geometric parameters of the spindle. Secondly, get the constraints and load of model by analyzing the working principle of the spindle system, it mainly includes bearing constraints, spindle back face constraints, cutting force load and rotating speed load, etc. For the calculation of the bearing constraints, in this paper, the bearing is simplified through combination spring. Then, the elastic modulus of the spring is calculated by stiffness coefficient empirical formula of bearing shaft. In addition, this paper also calculates the spindle suffered cutting forces by empirical formula.(2) Taking the spindle failure analysis as a starting point, analyzing and evaluating reliability and performance of spindle from both thermal failure and wear failure. For the spindle thermal failure, this paper analyzes that the heat is from friction of the bearing, and then develops spindle temperature test program according to the position of the heat source. Also, this paper gets spindle thermal simulation load values by empirical formula, and acquires spindle thermal simulation results by finite element thermal simulation. Finally, compares with the simulation data and experimental data can find that: the spindle does not produce thermal failure, and finite element model is reasonable.(3) For the spindle wear failure, above all, this paper establishes the relationship between the spindle wear extent and the amplitude by the empirical formula, and establishes the spindle vibration test, thus can obtains a function of the spindle amplitude and time. Then, it deduce a function of the spindle ware and time. Based on experience, the proportion of the spindle wear extent U and abrasion area S was about 3%, when the spindle occurrence failure. It mean that when U>3%S, the spindle would occur failure. Ultimately through failure conditions, calculate that the spindle MTBF is2248.2h.(4) At last, this paper develops mechanical reliability analysis software UEST_IORE based on reliability theory, it describes the software implementation process of each module. And it takes the spindle as analysis objects, shows software functionality perfectly, mainly includes: Stochastic analysis, reliability index calculation, thermal failure analysis and wear failure analysis, etc.