Advanced Materials Research Vol. 1136

Abstract: This paper describes the development of a direct drive motor (DD motor) without a reduction gear for the rotary motion of machine tools and its performance. We investigate novel DD motors from a view of total performance on machine tools. Moreover, we estimate to employ the developed DD motors for 5-axis control machine tools and the multi-functional machine tools. The study proves the required performance of rotary motion is achieved on machine tools, and the developed DD motors are found to be effective as follows. First, designing a DD motor with quality engineering and FEM analysis of electro-magnetic field is found to be effective for a low cogging torque and a low torque ripple. It is demonstrated that the developed DD motor makes it feasible to generate the excellent surface roughness on the complex shape workpiece with a ball-nose endmill tool, compared with the machined surface roughness by a conventional rotary axis with a reduction gear. Second, a maximum angular velocity of the DD motor is balanced with a maximum velocity of the linear axis, but a maximum angular acceleration of the DD motor is not balanced enough with a maximum acceleration of the linear axis. Therefore, the angular acceleration is needed to be improved as a next step.

Abstract: Ultra-high speed grinding (UHSG) is a significant and promising machining technology in grinding hard-to-cut materials. To find out the aerodynamics of the grinding wheel body when the airflow field has subsonic, transonic, and supersonic speed characteristics and clarify the corresponding influence on the grinding mechanism, the study is conducted to develop a supersonic grinding machine tool that is capable of being operated at extreme wheel speed up to 450 m/s and meanwhile accompanying with high grinding capability. In accordance with the main design objectives, a high performance grinding motorized spindle with maximum rotational speed 36000r/min and maximum power 28kW is developed. The linear motor feed driven system is also exploited to satisfy the requirement of maximum reciprocating speed up to 2m/s. Following plenty of specific design and performance analysis works, a prototype of supersonic grinding machine tool is finally developed. In the end, this paper also puts forward a number of further studies and prospective for the research activities on basis of the developed grinder.

Abstract: In grinding, the moving trajectories of abrasive grains are almost straight to the motion of the rotation and feed of the grinding wheel, so that grinding marks are formed continuously. As a result, surface roughness is dependent on grain size and organization of the grinding wheel. If the trajectory of the abrasive grain is wavy, the peak lines of the grinding marks will be partially removed by following the abrasive grain. This improves surface roughness. The objective of this study is to develop a mechanism to give axial vibration to the grinding wheel by the pulsation of the plunger pump, and thus to improve the surface roughness of the machined surface.

Abstract: The application of ceramics for knee prostheses promises a significant extension of the lifespan compared to conventional metal implants due to their outstanding mechanical and tribological properties. Nevertheless, grinding operations at the bone-faced surface of ceramic knee implants are limited. These limitations arise from an unfavorable accessibility of coolant lubricant. Caused by undercuts and concave surfaces the external coolant jet is deflected and does not reach the contact zone. In this paper, a prototype of a toric grinding tool with internal coolant supply is introduced. This innovative tool design enables a reliable and economic grinding process of the bone-faced surface of ceramic knee implants.

Abstract: We report on an ambitious project in the field of automation, applied to bound and free abrasive processing of precision and ultra-precision surfaces, with potentially far-reaching consequences. This involves two main aspects:- directly processing surfaces using industrial robots, and combining robots with Zeeko CNC polishing machines to automate operations that are currently manual. These form steps towards our ultimate vision of the Integrated Manufacturing Cell for bespoke optics rather than mass-produced, and manufacture of other precision surfaces including prosthetic joint implants. Projects such as the European Extremely Large Telescope provide a relevant case study, where significant numbers of high-value bespoke optics are required.