Applied Mechanics and Materials Vols. 10-12

Abstract: The tension of warp and weft run through the whole weaving process in knitted carpet weaving equipment. The performance of delivering warp mechanism and guiding weft mechanism in this kind of equipment influences the quality of carpet directly. A self-adjusting delivering warp mechanism is designed in this thesis, which is used in knitted carpet weaving equipment or other textile equipment that delivers warp by warp-spindle and demands even warp tension. The self-adjusting delivering warp mechanism consists of the device for setting and detecting warp tension, the device for driving warp-spindle in different speed, and the device for transmitting warp-spindle movement. The device for setting and detecting warp tension can determine initialization tension of warp, according to the technical requirements, can detect and feed back warp tension in real time. The device for driving warp-spindle in different speed makes the rotating speed of warp-spindle change according to the warp tension. The self-adjusting delivering warp mechanism realizes the function on controlling the rotating speed of warp-spindle in closed loop, and on stabilizing delivering warp tension.

Abstract: Water vapor is a good, pollution-free and economical coolants and lubricants in green machining. In order to research the cutting temperature distributions with water vapor as coolants and lubricants in machining, the experiments conducted under the conditions of water vapor as coolants and lubricants and dry cutting. The cutting temperatures are studied by metal cutting theory, and then by employing the finite element method (FEM), the temperature distribution of cutting region is simulated with application of water vapor as coolants and lubricants and dry cutting conditions. The results show that the water vapor jet flow has high force-convection heat transfer coefficient and directly cooling action to reduce cutting temperature, and the stress, the length of tool-chip interface are reduced with application of water vapor lubrication. So that the cutting thermal is decreased and water vapor has indirect cooling action. Under the conditions of indirect and direct cooling action, the cutting temperature is reduced obviously with application of water vapor as coolants and lubricants.

Abstract: This paper deals with a self-sealing flange system using O-ring as the potted component, and defines the design variables, restrictions and object function in the optimization. This study analyzes sealing performance of the flange system and quantifies it in optimization, and introduces the parameter of “maximal sealing gap” in optimizing computation instead of the concept of “sealing performance” which is too abstract to calculate, and then this paper analyzes the flange bolting and deduces the just bolt group of the flange system.

Abstract: Vibratory cutting is one of the newly developed machining techniques and theories in recent years. Insight into the machining mechanism and the chip formation process in metal vibratory cutting has yet to be carried out for this technique to be used widely and efficiently. But with conventional investigation, it is much difficult, and time and energy consuming to analyze and study such principles quantitatively. A system of the computer simulation has been established and based on FEM the chip formation process was emulated. The cutting forces and temperature distribution were imitated under condition of a variety of vibratory frequencies and turning engagements. ANSYS is utilized for the quantitative analysis. Contrast and comparison experiments between vibratory and the conventional metal machining are done, revealing a good agreement between the simulation and the experiment and the inborn nature and the principles of the vibratory metal cutting.

Abstract: In the process of the ultra-precision grinding, the machining path of the aspherical is the result of motor coordination by several axes for the numerical control system. Since the motion of each axis have errors, there are big errors between the real positions and the theoretical positions, and the position error of the wheel infects the accuracy of the workpiece greatly. This paper analyses the position error property of the wheel and finds the machining approach path has nothing to do with the position error, just do with to the present machining point. In order to solve the problem, the method using the Neural Network optimized by the Genetic Algorithm to establish the position error model is introduced. A three-layer error back propagation (simplified as BP) Neural Network is used to establish the position error model, the position coordinates (x, z) of the program instruction is input layer, and the corroding measured error value ( Δx , Δz ) is output layer. Before training data sample, using the Genetic Algorithm to optimize the Neural Network to improve the predicting accuracy of the Neural Network, and reduce the training time. The emulation results indicate that using the Neural Network model optimized by the Genetic Algorithm can predict the position error in a high degree of accuracy, and at the same time, according to the predicting results, compensating the position error of the wheel is possible.

Abstract: Powder mixed EDM can effectively improve the surface quality of a machined workpiece. In order to study the mechanism of powder mixed EDM process, particles’ activities in working conditions are simulated and corresponding experiments are done. A 3D electric fields model described by finite element method of the particles suspended in working fluid in the electric field is built, the generated field is computed and presented, and the activities of particles in the breakdown process are analyzed. The results show that this method can serve as a good way to learn the activities of particles in the breakdown of discharge.

Abstract: In this paper, cutting experiment and FEM simulation are combined to investigate the effect of various chamfered edge geometries on cutting force and cutting temperature distribution when hardened steel GCr15(HRC60+2) is machined with PCBN tool. The research results indicate that radial force and main cutting force increase with the enlargement of chamfer angle, and especially, radial force rises more significantly, but radial force is less than main cutting force during the entire cutting process. Cutting temperature also gradually rises as chamfer angle increases, and moreover, it is maximized on the chip-tool interface in a place of 0.1-0.2mm distant from nose.

Abstract: In 3-axis NC machining, most algorithms of the sculptured surface tool-path generation are valid for ball-cutter, and the axes are designed to realize pure translation. A tool-path generation algorithm using taper-cuter is proposed in this article. And one axis of the 3-axis NC tool machine is designed to realize swing motion. The Stereo Lithography (STL) model is the most popular triangular mesh approximation of the 3D surface model. Considering the special swing mechanical and taper-cutter, arc-zigzag tool-path planning and deform Z-map grid methods are proposed, which incorporate triangular vertexes method and the Z-map method. Finally, some simulation and experiment results are provided.

Abstract: This paper introduce a way to prepare Guizhou palygorskite mineral nanoparticles by dry-wet ball milling and modified its surface, with adding it in pre-polymer and dispersing with supersonic disperser. Then it introduced preparing the tung oil phenolic-formaldehyde (TPF)/ nano-palygorskite composite resin by situ. The TENSOR27 IR and JEM-2000FX II test shown that the nano-palygorskite particles embedded in the polymer and they were more evenly dispersed. By NETZSCHSTA409 thermal analyzer for TG analysis, the elevated of compound PF has been enhanced.

Abstract: The gear design always be focus on analyzing the static performance (strength, stress, friction) and dynamic performance (inertia, noise, vibration), and especially for dynamic, the noise and vibration of gear are big problems. Actually, the main reason of noise and vibration is transmission error between master and slave gears, but the error must exist in any manufacture process. To decrease harmful noise and vibration, the most effective method is “tooth profile modification”, which is by tip relief or root relief for modifying geometry profile of gear tooth to regulate transmission error. In the paper, the transmission error of original model and modified model will be compared to show the gear profile modification will influence the transmission error obviously.