A study of the machining of surgical implant material

近年来，为了消除钒对人体的毒理作用，不含钒的钛合金将取代Ti-6Al-4V系等传统类型的钛合金作为外科植入材料。总的来说，包括上述无钒合金在内的钛合金在切削过程中，刃口温升明显，强烈地促进了刀具与工件材料的粘附，导致刀具在较短的时间内失效。虽然外科植入物作为人工髋关节的主干在几种规格上是标准化的，但它们在大小和形状上的变化并不足以适合每个患者。为了使它们适合任何患者，需要这些植入物可以通过应用MRI或x射线CT获得的患者医学图像数据通过加工轻松制造。通过高温高压直接转化烧结制备无粘结剂PcBN刀具，提高了刀具的高温耐久性。将该刀具应用于常规Ti-6Al-4V合金和两种生物钛合金的切削加工，并对其切削性能进行了评价。无粘结剂PcBN加工Ti-6Al-4V合金刀具的耐磨性优于含co基粘结剂的硬质合金、PcBN和聚晶金刚石加工刀具。Ti-6Al-2Nb-1Ta合金的无粘结剂PcBN刀具在侧面磨损特性上与Ti-6Al-4V合金的PcBN刀具基本相当。另一方面，由于Ti-15Mo-5Zr-3Al合金的强度和韧性高于Ti-6Al-4V合金，因此在加工Ti-15Mo-5Zr-3Al合金时，刃口在早期失效。PcBN与钛合金在高热接触下发生反应，形成由Ti、B、Al组成的具有一定厚度的扩散层。说明无粘结剂PcBN刀具可提高高速铣削Ti- 15mo - 5zr - 3al合金的刀具寿命。少

Recently, titanium alloys without containing vanadium are going to applied for material of surgical implant in place of conventional type of titanium alloy such as Ti-6Al-4V system, in order to eliminate a toxicological effect of vanadium for human body. In general, the temperature rise in the cutting edge is significant in cutting process of titanium alloys including above mentioned vanadium-free alloys, promoted strongly the adhesion between tool and work materials, resulting in tool failure within relatively short duration. Although surgical implants as a stem of an artificial hip joint are standardized in several specifications, their variations in size and form are not enough to fit every patient. To make them fit to any patients, it is required that these implants can be manufactured easily by machining with application of the patient's medical image data obtained by MRI or X-ray CT. Improvement of processing efficiency was tried in machining of above described bio-titanium alloy … More s. A binder-less PcBN tool which is prepared through the direct conversion sintering of hBN under both high pressure and temperature, exhibits an improved high temperature durability. The tool was applied for machining of the conventional Ti-6Al-4V alloy and two types of bio-titanium alloys, then cutting performance are evaluated. The wear resistance of a binder-less PcBN tool for machining Ti-6Al-4V alloy was superior to those of the tools made of cemented carbide, PcBN and polycrystalline diamond with Co-based binder. The performance of the binder-less PcBN tool for Ti-6Al-2Nb-1Ta alloy was almost equivalent to that for the Ti-6Al-4V alloy in flank wear characteristics. On the other hand, for machining of the Ti-15Mo-5Zr-3Al alloy, the cutting edge failed in earlier stage due to its higher strength and toughness than Ti-6Al-4V alloy. The reaction between PcBN and titanium alloy under a high thermal contact produced the diffusion layer with certain thickness which consisted of Ti, B and Al. It was clarified that the binder-less PcBN tool could improve tool life in high-speed milling of the Ti-15Mo-5Zr-3Al alloy. Less