Titanium alloy is a kind of attractive materials for the artificial hip joints due to its special properties, which include excellent biocompatibility, high corrosion resistance, no allergic reaction and low weight. Acetabular cups can be manufactured using one of several manufacturing processes. One process is to machine the cups on a CNC lathe, another is to cast titanium alloy into the cups, and the other is to forge the cups. Each process has its own advantages and disadvantages. In the machining process and precision casting process, acetabular cups can be manufactured accurately. However machining process causes high production cost resulted from loss of raw material. Also precision casting leads to low productivity originated from complex process procedures. It is necessary to reduce cost and to increase production rate. In the cost and productivity points of view forging process can reduce loss of raw material and improve the productivity in comparison with machining process and precision casting process.
When titanium alloy is forged to manufactured acetabular cups, process parameters should be carefully designed to avoid defects such as lap, crack and under fill. In this study, it is intended to design the process parameters for hot forging of Ti-6Al-4V alloy by using a finite element analysis based thermo-viscoplastic theory. This kind of approach is good for minimize redesign of process parameters. From the analysis results, it is found that the initial temperature of the workpiece and ram speed are important parameters to improve forgeability of Ti-6Al-4V alloy.
The objective of this study is to propose a new technique for hot forging process of the acetabular cup. In order to find the range of the process parameters, the following two aspects are considered: ⅰ) the range of the initial temperature of the workpiece for enhancing mechanical properties of the forging of acetabular cups, ⅱ) the range of the ram speed for defect-free forging product. In order to show the validity of the proposed process parameters, the hot forging is also carried out using hydraulic press. From the comparison with the experiments with various process parameters, it has been shown that the proposed values of the parameters could be effectively applied practical manufacturing process for hot forging.
티타늄 합금은 뛰어난 내부식성, 낮은 비중, 우수한 기계적 성질 및 탁월한 생체적합성 때문에 인공고관절의 재료로 사용되고 있다. 인공고관절에 사용되는 비구컵은 기계가공 공정과 정밀 주조 공정을 이용하여 만들어지고 있는데, 기계 가공 공정으로 비구컵을 만들 경우, 칩 생성에 따른 재료손실이 발생한다. 그리고 정밀주조 공정을 사용하여 비구컵을 제작할 경우에는 복잡한 제조 공정으로 인한 생산성 저하와 높은 생산비용이 문제가 된다. 기존 공정이 가지는 이러한 문제점을 해결하기 위하여 본 논문에서는 비구컵의 열간 단조 공정 설계에 대한 연구를 수행하였다.