Advanced Materials Research Vols. 189-193

Abstract: An involute helical surface is one of the surfaces widely used in engineering. There are four characteristics lines ( involute, helix, straight generatrix, pathofcontact) on it. On the basis of characteristic lines, the shaping principle in hobbing is studied, the error characteristics and their interrelations are analyzed. The analysis formula of involute gear tooth surface errors is given for spur gears and helical gears.

Abstract: In order to improve the speed and accuracy of vision alignment for IC packaging, genetic algorithm and Otsu method are applied to vision alignment. According to the features of the image in IC packaging, an improved self-adaptive genetic algorithm combined with Otsu method is proposed in this paper, and the moment invariants method is used to carry out the remaining steps of vision alignment. Finally, experiments are undertaken by using a kind of IC chip, results show that the positioning error is less than 2μm, and the positioning time is less than 60ms.

Abstract: This paper presents a wireless transmission and data acquisition system for monitoring optical aspheric grinding environment. The hardware and software framework of the system is discussed. The result of experiments verifies the system is feasible in high precision aspheric surface manufacturing.

Abstract: Aiming at the problem that the traditional plunged-bar method is difficult to meet the measurement requirement of spatial location of thin and small through-hole, in this paper, the digital image processing technique combined with sub-pixel detection technique is employed, and a new method is proposed to detect the tiny through-holes. The evaluating function method based on the “roundness” of the image of hole is presented to find out the posture parameters of CCD where the optical axis of CCD is parallel to the centerline of hole. Therefore, the spatial location of hole can be easily obtained by these posture parameters. Meanwhile, the diameter of hole can be achieved by means of image measuring technology at calculated posture of CCD. Owing to the non-contact measurement, this method is particularly suitable for those small through-holes drilled on the soft and easy-deformed object. The experiment results on the experimental platform illustrate the feasibility and validity of this method.

Abstract: The image distortion which comes from aberration is analyzed and the effects on focal line features are also discussed, which are resulted from the spherical aberration, chromatic aberration and beam spread. The simulation results have show that source imperfection, especially the transverse velocity spread, plays a critical role in broadening the feature width.

Abstract: The failure of the gas valve’s external screw taper thread is a very serious problem which may result in accidents. Routine inspection on the threads is thus necessary. The efficiency of traditional manual testing methods can not meet the production requirements. An automatic visual inspection system for gas valve’s external screw taper thread is presented in the paper. The system consists of a high-performance 200 mega pixels CCD camera, a LED backlight and a holder of gas valve. Through image acquisition, image processing, edge detection and feature dimension measurement, the system can effectively measure the parameters of taper thread such as half of thread angle, depth of thread, taper angle of thread on image domain. Due to the lead angle and installation error, actual half of thread angle is different from the theoretical values. Three methods are presented in the paper for the half of thread angle. Through analysis, Method 3 and Method 2 can be used to measure half of thread angle. The system can meet the testing requirements of the external screw taper thread and has wide application perspective.

Abstract: To solve the critical problem of large gear deviation on-machine: angle displacement measurement that is how to get signal acquisition and accuracy analysis of angle displacement. A new measuring method is proposed, which applies the dividing mechanism (it is composed of friction disc and circular grating) to ensure index and pick up signal of gear corner correctly and strictly according to the principle of angular displacement measurement. Furthermore, the main error which affects measurement accuracy is analyzed, and accuracy is analyzed with geometrical theory such as Fourier series and error synthesis principle etc. The experimental results indicate that angel dividing and signal samplings are easier and more efficient by the dividing mechanism, furthermore, the accuracy is in the range of total error that is permitted by verification, and the mechanism can also meet the requirement of high accuracy, so the method is significance that assessing transmission accuracy of involutes gear.

Abstract: In according to the DEFORM-3D software, we simulated the decarburization depth of the 60Si2CrVA spring steel in heat treatment, optimized the process parameters with the simulation results. The result of the research illustrated that the actual decarburization depth is consistent with the simulation result, which demonstrate DEFORM-3D has a practical guide for the process of heat treatment.

Abstract: This paper presents an improved genetic algorithm for the job shop scheduling problem. We designed a new encoding method based on operation order matrix, a matrix correspond to a chromosome, the value of elements is not repetitive, that means a processing order number in all operations of all jobs. Aiming at the features of the matrix encoding, we designed the crossover and mutation methods based on jobs, and the infeasible solutions are avoided. Through adjusting the computing method of fitness value, the improved genetic algorithm takes on some self adapting capability. The proposed approach is tested on some standard instances and compared with two other approaches. The computation results validate the algorithm is efficient.

Abstract: The structure and mechanical properties of pipeline steel X80 through HTP rolled into 16mm thick slab were tested. The results show that the yield strength of tested has reached above 600Mpa, and the ratio of tensile strength to yield strength is 0.86, and duetile brittle transition temperature is lower than -60°C , and good strength and toughness are obtained. Low content of P, S, high content of Mn and fine microstructure have good effect on reducing the ductile-brittle transitiop temperature. Two different precipitations are observed in pipeline steel X80, a class of TiN precipitations is mainly and a small number of (Nb, V)(C, N) complex precipitations in the TiN around, and the other for large number of NbC precipitations and a small amount of TiC、VC and simultaneous deposition of the complex formed precipitations. Remarkable strengthening and grain refinement can ne caused by these precipitations.