Key Engineering Materials Vols. 315-316

Abstract: As high-speed steel tap is incapable of small-hole tapping (M3) in hardened steel, vibration tapping is introduced in this paper to solve this problem. Theoretic analysis with fracture mechanics indicates that the impact effect of the tap on the workpiece results in extended micro cracks and a much lower tapping torque. And the torsional rigidity of the tap is enforced in vibration tapping as proved by dynamic analysis. The experimental results show that with well chosen amplitudes, tapping torque decreases as vibration frequency increases and increases with the increase of net cutting time ratio, with the latter being the more significant influencing factor. In vibration tapping of hardened steel, 24 threads can be machined with a single tap. Vibration tapping is then proved to be a practical solution to the problem of small-hole tapping in hardened steel.

Abstract: A new principle and technology of point form grinding for quadratic surface flank of twist drill was investigated. It broke through the traditional straight-line generator grinding method for the conical and the spiral drills. The principle of implementation mechanism was given in the paper. The trueness and feasibility of the method had been approved in the experiments, and the quadratic surface twist drill such as hyperboloid, ellipsoid and hyperboloid-ellipsoid compound flank had been grinded on the mechanism.

Abstract: The surface treatment for TC4 alloy was conducted by MEVVA ion implantation method. The corrosion resistance of TC4 alloy implanted by La+, Mo+ were measured. It were found that Mo ion implantation improved corrosion resistance of TC4 alloy in acidic chloride solution, but La ion implantation gave the opposite result because they have different chemical activity. The more implanted dose of Mo+, the more improvement of corrosion resistance.

Abstract: With the continuous development and popularity of optical sensor and computer vision, machining process monitoring based on CCD camera has attracted more and more attention in recent years. Aiming at detecting the shape of cutting chip forming in cylindrical turning, a special matching algorithm is presented in this paper. As a reliable measuring method of chip shape parameter doesn’t exist, this algorithm can hardly be verified in a precise manner, however comparison between experimental results and the original images shows that this matching algorithm is effective. A double-CCD stereoscopic vision monitoring system employing this algorithm can be used to estimate the wearing and breakage of tool, and provide significant instruction for the design of tool groove for its capability of in-process measuring chip shape.

Abstract: Ultrasonic vibration aided electrical discharge machining (UEDM) in gas is an electrical discharge machining (EDM) technology, in which gases such as air and oxygen are used as dielectrics and ultrasonic vibration is applied. UEDM in gas can avoid environment pollution, the most serious disadvantage of conventional EDM in kerosene-based oil or other dielectric fluids, and it is environmental-friendly. The technology also possesses virtues of wide applications, high machining efficiency and simple tool electrodes and so on. The principle of UEDM in gas is introduced in this paper. Experiments have been carried out to study the effects of machining parameters on material removal rate (MRR), surface roughness of the workpiece and tool electrode wear ratio (TWR), and the experiments results have also been analyzed.

Abstract: To improve the cutting efficiency, one of key approaches is to control with constant force in the full depth working condition. And the controller design is vital to realize the real-time feasibility and robustness of the system. A neuron optimization based PID approach is proposed in this paper and adopted in the NC cutting process. This approach optimizes the parameters of PID controller real-timely with the neural network control principle. It not only overcomes the mismatch of the open-loop system model which occurred in constant PID control, but also solves the contradiction between the calculation speed and precision in the neural network which caused by the node choosing of the hidden layer. At last, the simulation has been carried out on a NC milling machine to prove the validity and effectiveness of the proposed approach.

Abstract: Ceramic plunger couple are appreciated by engine designer thanks to its high performances such as anticorrosion and wearproof, however which are restricted due to machining difficulty. This article will discuss the feasibility of replacing metal material with silicon nitride ceramics in plunger coupler manufacturing through analysis on change law of stress and displacement of 12150L diesel engine plunger coupler at rated condition, design and develop special clamp for intractable spiral line and oil-out trough, and with satisfactory machining effect.

Abstract: Three ceramic composite were prepared by hot pressing sintering. The friction and wear behaviors of the composite were experimented at the high speed wear and tear test machine. Results show that the three ceramic composite have strong fracture toughness and flexure strength. The wear mechanisms of three ceramic composite are mainly brittleness peel off and furrow. Al2O3/(W, Ti)C and Al2O3/SiCw ceramic composite have great capabilities in wear resistance; they are excellent materials of cutting tools and dies.