Materials Science Forum Vols. 800-801

Abstract: In the deep hole boring, the vibration of the boring bar is greater. In order to improve the machining processing efficiency and quality of the deep hole boring, this paper designs the deep hole damping boring bar with a single oscillator firstly. It builds a simplified dynamic model of the damping boring bar and calculates its relevant parameters. Moreover, with different external excitation force frequency, the maximum amplitude variation of the boring bar tip position is obtained from the simulation analysis. Finally, the experiments show that: Compared with the hollow boring bar and the solid boring bar, the damping effect of large aspect ratio vibration boring bar increases about 75%.

Abstract: In this paper, a new kind of ellipsoid end mill is proposed in order to improve the quality and efficiency in machining the sculptured surface. An integral ellipsoid end mill parameter optimization system architecture is developed to make the parametric design automatically and efficiently. Then, the mathematical model of continuous blade curve with constant helix angle and normal helix cutting edge of ellipsoid end mill is presented, as well as the cutting edge on the cylinder of cylindrical ellipsoid end mill. And then, all curves are simulated based on MATLAB software. Finally, the ellipsoid end mill is manufactured using a SAACKE UWIF CNC grinding machine to verify the feasibility of ellipsoid end mill.

Abstract: According to the principle of ultrasonic vibration turning, the first step is to study different position changes of surface roughness with cutting parameters under ultrasonic vibration turning of slender shaft by the test of single factor, and determining the extreme position of surface roughness with the slender shaft changes in different cutting conditions. The second step is to study the influence of cutting parameters on the overall average surface roughness of work piece under ultrasonic vibration turning of slender shaft by orthogonal test design, and compared with the conventional turning. The experimental results show that ultrasonic vibration turning slender shaft processing can significantly improve the surface roughness. At the same time, the influence laws of cutting parameters on the surface roughness are investigated, and finding out the optimal cutting experimental parameters.

Abstract: With the new type of high strength , high hardness difficult machining parts appear constantly, both for the quality of deep processing, durability of the tools, or reliability of the drilling systems are putting forward higher requirements. This paper mainly describes the characteristics of deep-hole drilling systems and applications, and content selection of cutting parameters, impact of cutting speed and feed rate for chip breaking and so do some explanation, These have certain guiding significance for chip breaking can get better. Finally, introduce the deep-hole drilling in the drilling process causes common problems and solutions, to provide some references for practical manufacture process.

Abstract: Close attention has been paid to Functional graded materials (FGMs) worldwide for their novel design ideas and outstanding properties. To verify the advantage of FGMS in the design of ceramic tool materials, Si₃N₄/(W, Ti)C nanocomposite ceramic tool materials with homogenous and graded structure were fabricated by hot pressing and sintering technology. The flexural strength, fracture toughness and hardness of the sintered composites were tested and compared. The experimental results showed that the graded structure improved mechanical properties of the ceramic tool materials, especially the flexural strength and fracture toughness. The introduction of residual compressive stress in the surface layer contributes to the improvement of the properties .

Abstract: Focus on the problems that heavy duty machine tool lack of fault samples and process information in repetitive assembly, result in the existing assembly process method can’t meet the repetitive assembly accuracy. According to characteristics of local machine assembly process, propose its assembly repeatability evaluation indexes. Establish the mapping relation among machine performance, assembly accuracy and structure, and built a hierarchical model of assembly process, obtain the process optimal design scheme of assembly accuracy repeatability. Use the multivariate function differential method, propose a calculation method of heavy machine assembly accuracy, and verify applicability of the method, depend on the machine loads and structure criterions, propose heavy machine assembly accuracy repeatability optimization method, example analysis shows that: the servo effect of repetitive assembly accuracy in new process is obvious, simultaneously stress field magnitude and stability of new technology is better than the original, realize effective control of the machine tool assembly accuracy repeatability.

Abstract: A kind of compound servo drive system is designed using the characteristics of hydraulic motor large torque and servo motor high accuracy positioning. Proportional pressure valve, proportional flow valve and electromagnetic directional valve was used to control hydraulic motor for tracking servo motor drive control and to achieve servo motor control for weight load of large torque and high accuracy positioning. Pressure, speed control strategy of using PID control is proposed based on the above hydraulic tracking drive system, achieve precise control for trajectory of robot articulated arm under heavy load conditions. And according to the requirements of the pressure, flow rate and reversing in the process of compound servo drive, a torque, speed and direction of the switching control strategy is put forward. Mathematical model is established and simulated based on tracking control system. The experiments indicate: under heavy load conditions, response speed, torque and angle control accuracy of hydraulic hybrid drive system meet the requirements with this control method and torque, speed switching control strategy.

Abstract: The milling experiments were carried out using TiAlN and PCD coated carbide tools in high speed milling Ti6Al4V to compare and analyze tool wear and tool life of the two kinds of coating carbide tools. In addition, the effect of cooling and lubricating on tool wear is also studied. The results showed that fluid environment is not suitable for milling Ti6Al4V. PCD coating carbide tool can effectively increase the life of tool in high speed milling of Ti6Al4V.

Abstract: In order to find and repair surface damage on KDP crystal, an open computer numerical control(CNC) system has been developed. This paper introduces the hardware structure of the control system, explains the development of an open CNC system software, which has friendly human-machine interface (HMI) and can make the finding and repairing process efficiently and conveniently and also expounds the algorithm and related parameters for servo tuning. With the open CNC system, the process of finding surface damage is accomplished in 3 hours and clear images of crystal surface damage is taken by CCD. And also, with the help of the open CNC system, a 600µm-diameter, 25µm-depth Gaussian repair contour with low roughness is obtained. Experimental results prove that the open CNC system for finding and repairing surface damage on KDP crystal meets the requirement of efficient detection and ultra-precision machining.

Abstract: The ultra-precision floating motion platform is the key device for equipment detectingand processing optical elements, and this paper mainly studies the floating motion platform used fordetecting the surface detects in KDP crystal. The load capacity of air cushion supporting the floatingmotion platform is studied theoretically and experimentally, and finally the supply pressure of thefour air cushions were optimized under the guidance of its load characteristic curve. The structureparameter of plane flexure hinge, a key part of floating motion platform, is optimized and thesimulation results show that the optimized plane flexure hinge can eliminate the disturbance inZ-direction obviously, which is produced by the two motors. Finally the support position of crystalholder is optimized by means of static and modal analysis; and the set of optimized support way canmake the maximum deformation of the platform reducing by 2μm and make the 1st order naturalfrequency increase from 49.078Hz to 51.787Hz.