| With the increasing demand for surgery and the rapid development of robot technology,more and more automated surgical systems and medical robots are applied in clinical practice.Bone cutting,as one of the most common operations in orthopedic surgery,is also performed by orthopedic robots.However,due to the complex composition and structure of biological bone,as well as its material characteristics such as anisotropy and low thermal conductivity,excessive drilling force and temperature during drilling can cause mechanical damage and thermal necrosis of bone tissue near the hole.Moreover,skidding may occur during drilling.These factors can reduce the quality of surgery and postoperative recovery of patients.Therefore,it is of great significance to study the cutting mechanism of biological bone materials,control the drilling force and temperature during drilling,suppress drill skid,and achieve lowdamage bone drilling for the development of high-quality orthopedic surgical technology.The design of new orthopedic cutting tools is one of the most economical and feasible methods to achieve these goals and has important research value.This thesis mainly investigates the following topics:(1)Focusing on the target of low-damage bone drilling,a biomechanical orthogonal cutting experimental platform was built,starting with the bone cutting mechanism.The mechanism of chip formation in orthogonal bone cutting was investigated,and the influence of tool parameters on bone cutting mechanism was analyzed.Furthermore,a mechanical model for orthogonal and oblique cutting of bone was established,and the orthogonal cutting force was analyzed.(2)The key geometric parameters of the drill tip were calculated,and a model for the difference in chip area was established based on the drill tip parameters.A novel orthopedic crescent drill was designed based on the transformation of cutting mechanism and the suppression of skid,aiming to achieve the goal of low-damage bone drilling.(3)Based on the cutting mechanism and geometric parameters of different cutting edges,combined with the characteristics of bone materials,drilling force and torque prediction models for twist drills and crescent drills were established.An experimental platform was built,and the effectiveness of the models was verified through experiments on drilling holes in cortical bone.The model can also be applied to other types of drills with straight or curved cutting edges.(4)In response to the main problems encountered during bone drilling,such as skid,surface damage,drilling force,and drilling temperature,the bone drilling performance of the proposed crescent drill was evaluated comprehensively from multiple dimensions.Experimental results showed that both types of new crescent drills did not skid,significantly improved the surface quality of bone drilling,reduced drilling force and drilling temperature,and could effectively improve the quality of drilling and reduce the burden on doctors. |
