جستجوی مقالات مرتبط با کلیدواژه « پیچ ستون فقرات » در نشریات گروه « مکانیک »

The production of orthopedic screws of Ti6Al4V alloy presents challenges due to the need for a fast, cost-effective method of cutting difficult-to-cut alloys. This study addresses these issues by determining the kinematics of thread whirling for orthopedic screws made of Ti6Al4V alloy and investigating the effect of cutting parameters on the dimensional accuracy and texture of spinal screws. The proposed method enables rapid production while maintaining high precision. The main process parameters, such as tool rotational speed and workpiece feed rate, were varied at two levels for a total of four samples. The output parameters included surface roughness, thread root surface texture, sidewall profile, and thread angle. The results showed that a higher feed rate produced a rougher thread root surface and a lower ploughing effect. This increased roughness was considered ideal because it promotes cell growth on the screw surface and improves screw osteointegration in bone tissue. Furthermore, increasing the cutting speed, while creating a serrated texture on the thread wall, improved overall screw quality by reducing cutting force and eliminating crown thread defects. Within the specified manufacturing tolerance, the effect of cutting parameters on thread angle was negligible.

Thread whirling has been used in manufacturing spine screws instead of normal threading. The main advantage of thread whirling is high-speed production along with high precision. In this method, a whirling module and tool holder with specialized inserts have been used. The mentioned module is adjusted and connected to the machine at different angles according to the geometry of the thread. In this research, the thread whirling method was conducted on four pedicle screws made of Ti6Al4V to investigate the effect of the main cutting parameters, including cutting speed and feed rate on the surface integrity and dimensional accuracy. Based on the results, the obtained tolerances of the threads were in the acceptable range. In addition, the increased cutting speed reduced the surface integrity of the threads by plowing.