Saha S, Pal S, Albright J A
J Biomech Eng. 1982 Aug;104(3):245-52. doi: 10.1115/1.3138356.
The majority of twist drills used in orthopaedics are very similar to chisel pointed metal drilling bits. Modifications usually observed are reduction of the point angle to 90 deg and sometimes grinding of the entire cutting lip at 0 deg rake angle, which appeared to have been made arbitrarily without any advantage. We have attempted to design a surgical drill bit with the objective of minimization of the drilling thrust and temperature and effective removal of bone chips. Our results showed that the presence of the chisel edge was mainly responsible for increasing the thrust force and the temperature developed. The effects of a constant feed rate and thrust on the peak temperature were also examined. The combined effect of the helix and the point angles on the rake angle which in turn determines the cutting efficiency was analyzed for various types of surgical bits. Based on our results and previously published data from the literature an optimized drill bit was designed with a split point, a point angle of 118 deg, a parabolic flute, and a helix angle of 36 deg and its performance was compared with other existing surgical drill bits. For drilling in compact bone, the new design decreased the thrust load by 45 percent an the peak temperature rise by 41 percent. Similar improvements were also recorded for drilling bone cement. The time of drilling a bone cortex was also significantly reduced and "walking" on the curved bone surface was eliminated and dimensional tolerance on hole sizes was improved. The new design is likely to reduce the time of surgery and also minimize the tissue damage.
骨科手术中使用的大多数麻花钻与凿尖金属钻头非常相似。常见的改进通常是将顶角减小到90度，有时还会将整个切削刃磨成0度前角，这种改进似乎是随意进行的，没有任何优势。我们试图设计一种手术钻头，目的是将钻孔推力和温度降至最低，并有效清除骨屑。我们的结果表明，横刃的存在是增加推力和产生温度的主要原因。还研究了恒定进给速度和推力对峰值温度的影响。分析了螺旋角和顶角对前角的综合影响，而前角又决定了切削效率，针对各种类型的手术钻头进行了分析。根据我们的结果以及文献中先前发表的数据，设计了一种优化的钻头，其特点是有一个分尖、118度的顶角、抛物线形的排屑槽和36度的螺旋角，并将其性能与其他现有的手术钻头进行了比较。对于致密骨钻孔，新设计使推力负荷降低了45%，峰值温度升高降低了41%。在钻骨水泥时也记录到了类似的改进。钻透骨皮质的时间也显著减少，在弯曲骨表面的“打滑”现象消除了，孔尺寸的尺寸公差得到了改善。新设计可能会减少手术时间，并使组织损伤最小化。
