Wen Hui Zhao

Study on Precision Analysis and Simulation Test of Upper Slicing System

The multislice spiral computed tomography (MSCT) is famous for the small radiation,large volume scanning and quickly reconstruction, and it becomes the first choice in clinical examination. The upper slicing system is the main components of the optical system in MSCT. This paper focuses on the design of upper slicing slice system and its precision analysis to improve the precision of imaging. The error of slice thickness and ray center by bearings, screw and control system is analyzed and tested. Improving the precision of the upper slicing system contributes to determine the appropriate treatment methods to improve the success rate of treatment.

Research on Nonlinear Modeling and Simulation for Flexible Drive Train of Wind Turbine

Wind energy has preferable economic and social benefits because of its cleanliness and free pollution, short construction period, and so on. The wind turbine is a complicated nonlinear uncertain system. So the modeling and analysis of system is crucial to the system design of wind turbines. Drive train performance of wind turbine was analyzed, and modeling methods were presented according to rigid drive train and flexible drive train. Based on those models, software has been designed to show the performance of the wind turbine, and then contrast with the result that simulated by GH Bladed software, to verify the accuracy of the models. The results show that the models can be used in optimum design and control strategy.

Study on CCD Measurement System Based on Image Processing

The measurement system based on industry CCD and image processing was established to measure 2D sizes of parts. The CCD sensors, lenses, illumination and image acquisition modes were chosen to establish hardware part, according to the requirement of views and precision. The software system was developed to extract the edge of the part from the digital image and transform it to a polynomial. The actual sizes of the part were measured with relative comparison calibrating method. Tests and analyses show that it is an untouched, automatic 2D Measurement system with high accuracy.

Computation and Simulation of 5-Axis Cutter Based on Scattered Point Cloud Data

The complex surface is modeled by triangular surface, B-spline or non-uniform rational B-spline first and then the planing of the cutter is followed in reverse engineering. But this require CAD/CAM software and operator’s experiene. Because of this，the research on direct NC cutter generation from point cloud have become the focus of research in reverse engineering. The normal，curvature，surface vary et al parameters are calculated by principle component analysis method and so on, which define the local feature of the surface hidden in the point cloud. Then，based on local feature，point cloud is simplified. It is proved that two points with minimal orientation-distance on a pair of smooth surfaces are conjugate points. Thus the conjugate problem between the tool surface and the part surface is converted into optimization process of orientation-distance function. The cutter trace and the cutter interference are achieved by local and global optization of the orientation-distance function.

Tool Path Calculation Based on the Actual Tool Profile

Due to tool wear and making errors, calculating the tool path based on the tool theory model has a great deal of influence on the accuracy of surface finishing machining. In order to solve the above problem, a photogrammetry method is used to extract the rotary cutter profile, and then the tool surface is get by letting the fitting profile curve revolves about the cutter axis, finally the cutter contact path is obtained based on the minimal orientation-distance algorithm. Experiments prove the cutter contact path is just on the theory surface of the workpiece. Therefore the accuracy of surface finishing machining will be greatly improved by the method.

Research on On-line Detection and Data Processing Technology of Welding Seam for Bellow

In order to improve the welding quality and welding speed of irregular bellows, according to the characteristic of welding seam of bellows, an automatic and on-line detection technology is proposed in welding technique. The infrared laser sensor is used for measuring with non-contact and real-time detection of welded joint center, the position of welding seam is transfered by the IEEE-1394(Fire Wire). After data preprocessing, the coordinates of feature point are extracted, be storaged and forecasted, then sent to the control system, the moving of welding gun is controlled along track scanning. According to the accuracy analysis of on-line detection system of bellows, the technology of tracking measurement is stable and reliable, and it is effective for improving measuring accuracy and efficiency.

Study on Construction of Tyre Tread Pattern Mold and its Machining with 3-Axis Numerical Control

Tyre tread pattern mainly accounts for tyre performance and its endurance. In tyre mold processing, pattern block processing is technologically disturbing, of which the tread pattern is the most challenging. This article first analyses the function conversion of the points from point to plane to space along the tyre tread curve. Aided by GRIP language, it continues to make tread section with spatial curve, and then with the help of UG scanning order, it produces a three-dimensional diorama of accurate tyre pattern. To solve the problem of large errors arising in tyre mold processing with 3 axis numerical control technology, the article proposes a new method to produce tyre tread pattern with 3 axis technology and validates the method. The research contributes to dividing processing of tyre tread pattern, and reducing errors theoretically. Experiments had been done to illustrate that the method can achieve high quality and efficient processing.

Study on Machining and Measurement for Borosilicate Glass Conical Ellipsoid

Surfaces formed by rotating quadratic curve are widely applied in engineering practice. After having studied machining methods and machines, the CNC grinding method based on macro program B for borosilicate glass elliptical cone surface machine with high precision is proposed. Within the allowable error, the coordinates are calculated according to the equation of axial section curve and the surface is formed with tools moving on axial section curve. Through setting parameters of the lathe, the new canned cycle can be defined to process all different kinds of the elliptical cone surface of same type. With surface triangle adaptive measurement method, machined elliptical cone surface can be detected on coordinate-measuring machine and compared with the theoretical curve. The tolerance resulted from analysis is within 0.025mm. Except ellipsoidal surface all solids of rotation and their deformation, in which their axial sections are represented with equation, can be processed and measured with this method.

Study on Industrial Waste Sites Monitoring Based on Remote Sensing Technology

Large scale of the industrial waste is not timely disposed of due to economic rapid development. It is the main reason why environmental pollution problem is getting more and more serious and we should monitor the pollution of industrial waste. A MODIS (Moderate Resolution Imaging Spectroradiometer) senor is used for long-time and dynamic environment monitor because it has advantages of high time resolution and high spectral resolution characteristics etc. SPOT satellite data is used to analyze the ground vegetation for its higher ground resolution and rich product data bases. The influence of industrial waste on environment is analyzed and the result of research is verifyed with the information of local meteorological agent and observation data of site. This method can be used for monitoring wide-range industrial waste and have good performance of monitoring and early warning industrial waste sites which are in mountainous area.

On-Line Detection and Tracking Welding Control Technology of Thin-Walled Bellow

In order to improve the welding speed, quality and automation level of thin-walled bellow, on-line detection and tracking welding control technology is proposed which includes on-line detection system and tracking welding control system. Based on laser sensor, on-line detection system can rapidly filter the data, and the data is stored in a queue, the control system which is based on motion control card is developed by using ActiveX controls for programming, VB is used to develop the integrated user operating system, other control tasks are completely integrated on this system to realize real-time welding control bellow. Results showed that the system is reliable and effectively, the automation level of the bellow welding is greatly improved.