Papers by Author: Pei Pei Zhang

Abstract: Titanium alloy (TC18) is new style alloy (α+β). It possesses better performances than common titanium alloy. However, Titanium alloy (TC18) is still classified as difficult-to-machine materials for their poor machinability, which is attributed to relatively low modulus of elasticity, strong alloying tendency or chemical reactivity with cutting materials at higher temperatures and low conductivity of heat generated by the cutting action. Due to the poor machinability of the alloys, selecting of insert style is crucial for tool life and material removal rate. In this work, milling tests, using three kinds of inserts (KC522M, YD201 and SANDVIK 4240), were carried out on this kind of titanium alloy (TC18). The results of tests show that the material removal rate of insert KC522M is the highest, but its tool life is shorter compared with insert SANDVIK 4240. The material removal rate and tool life of insert YD201 do not draw the attention because both of them are relatively low. The abrasion speed of insert SANDVIK 4240 is slow and the efficiency is high, so it is ideal for machining titanium alloy (TC18). In addition, the optimal machining parameters of insert SANDVIK 4240 for milling titanium alloy (TC18) were also given in this paper.

Abstract: This paper aims to develop a new Response Surface Methodology (RSM)— XU-RSM— adapted to Reliability-Based Design Optimization (RBDO) based on Diffuse Approximation (DA) and First-Order Reliability Method (FORM). The essential of the new response surface methodology is to use simultaneously the points both in a design space (X-space) and an independent standard normal random space (U-space). Mixing the points allows for more precise local approximation due to denser sampling points and leads to a faster convergence. Finally, a mathematic example is given to show how to use the new method and the comparison of results of evolutions.

Abstract: The selection of adaptable machining parameters is a key part in numerical control (NC) milling process. Deterministic optimal parameters are obtained without considering the uncertainties of machine tools. So a reliable optimization method was introduced in this study. We focus on a response surface methodology (RSM) adapted to reliability-based design optimization (RBDO) based on Diffuse Approximation (DA). A variant of the first order reliability method (FORM) is chosen to calculate the safety index. Case study is investigated for the NC milling operations of ultrahigh strength steel. We show how to get the optimal parameters with the safety index by the reliable optimization method.