Applied Mechanics and Materials Vol. 159

Abstract: The focus of this paper is to find a new method analyzing the reasons of CNC machine tool precision recession. The modeling of the movement error of CNC machine tool is one of the most important problem for kinematics designing and accuracy analysis. In this dissertation, this study analyzes the six movement error parameters of guide and the model of the guide which including foundation deformation, material’s natural ageing and way rub has been established. A detailed example is given for the modeling precision recession of 3-axis CNC machine tool.

Abstract: In order to solve the problem of removing uneven and improve processing quality for automatic polishing free curve surface of dies, a new technique based on fuzzy control is put forward in the thesis. Polishing pressure and rotate speed of grinding wheel will be changed according to the curvature of free curve surface, the results of simulation and experiment show the method is excellent for removing material evenly, reducing the values of surface roughness and improving the surface quality of parts, which provides good basis of practical research and application of accurate working for free surface of dies.

Abstract: In this paper we study how to trade off the economic and ecological effects in the remanufacturing closed-loop logistics network design in the context of low-carbon economy. We establish a multi-objective mixed integer linear programming model to find the optimal facility locations and materials flow allocation. In the objective function, we set three minimum targets: economic cost, CO2 emission and waste generation. Through an iterative algorithm, we get the Pareto Frontier of our problem. In the numeric study, we find that in order to achieve a Pareto improvement over an original system, three of the critical rates (i.e. return rate, recovery rate, and cost substitute rate) should be increased. Also, to meet the need of low-carbon dioxide, we plot an iso-CO2 emission curve in which decision makers have a series of optimal choices with the same CO2 emission but different cost and waste generation. Each choice may have different network design but all of these are Pareto optimal solutions, which provide a comprehensive evaluation of both economics and ecology for the decision making.

Abstract: Based on the characteristics of the automobile diagnosis system scheme, this paper has established the parameter system of diagnosis system scheme evaluation. Aiming at automobile diagnosis system scheme is difficult to evaluate its condition because of its structure is complex and its monitoring parameters are complicated and various, a second order fuzzy comprehensive evaluation model is proposed. The case study results show that the proposed model is feasible and effective. Hence, the evaluated results can aid to automobile diagnosis system design.

Abstract: CNC ultrasonic machining is an effective method to machine hard and fragile materials. It can realize producing complicate-shaped parts with simple tools. Mechanism of CNC ultrasonic machining was presented. The main components of CNC ultrasonic machine tool were analyzed, including the principle of the ultrasonic generator, selecting suited transducer, designing appropriate horn and impedance matching of tools. Finally, developing tendency of the CNC ultrasonic machining was discussed.

Abstract: During the cold rolling forming of non-symmetric Z-section steel, the twist will appear because two sides of the blank suffering bending moments of the same direction. In this paper, simplified FE model was used to simulate the closing process of the rolls. The contact forces of the rollers on blank, and the stress and strain of the blank was obtained by FE analysis, and relations between section torque and the position angle θ as studied and the result that when θ=10⁰ the torque is minimum was discovered. The further detailed calculations showed that angle θ was only correlative with the geometry of the product section and didn’t change with the altering of material properties.

Abstract: The dynamic radius of a driving wheel, especially for the off-road vehicles, has not been identified clear so far. This article reveals the relationships between the dynamic radius and the slip ratio of a driving wheel by theoretical analysis and experimental researches. The movement characteristics of a rigid driving wheel and an elastic pneumatic driving tire on soft roads are explained. There are many kinds of methods to measure the dynamic radius, and the magnitude of the dynamic radius is not the same according to the methods. A certain measuring method should be chosen for each kind of road conditions in order to reduce the measuring error.

Abstract: Abstract: In the light of the problem of low efficiency in reverse engineering model reconstruction, taking Auto part as object of study, analysis the key technology in this paper. One method is proposed to improve the design efficiency for Auto part model reconstruction. First of all, point cloud is acquired by camera style 3D scanner and processed by Geomagic software; then it is imported to CATIA software for Parameters reproduction and model reconstruction. Results show that this method can improve the efficiency of Auto part model reconstruction, and provide one workable way for CAD model reconstruction with complex surface.

Abstract: Al-Zn-Mg-Cu super-high strength aluminum alloy is widely used in the aerospace and automotive industry. However, the extrudability of Al-Zn-Mg-Cu aluminum alloy is relatively poor compared with other series of aluminum alloys. The simulation of compound cold extrusion process of Al-Zn-Mg-Cu aluminum alloy was studied for the production of a double-cup workpiece with a deep wobbler hole in this paper. The effective strain and stress distribution of the alloy during cold extrusion were studied by Deform-3D simulation. The results show that the maximum stress was concentrated at the bottom of the deep hole. Cracks were easily to be occured near the bottom of deep-hole. Based on the experimental results, the processing route of the two steps with compound cold extrusion is more suitable than one cold extrusion for the production.

Abstract: Soft Abrasive Flow Machining (SAFM) was presented as a new finishing process about the existing problems that the irregular surface of plastic mould was polishing difficultly. The paper first introduced the working principle and feature of SAMF. Secondly, the main influences of SAFM were analyzed. The problem of technology and theory urgent to settle was discussed. At the last, the technology development of SAFM was expected.