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Cao H.-J.,Chongqing University | Li H.-C.,Chongqing University | Song S.-L.,Chongqing University | Du Y.-B.,Chongqing University | Chen P.,Chongqing Machine Tool Group Co.
Jisuanji Jicheng Zhizao Xitong/Computer Integrated Manufacturing Systems, CIMS

According to the analysis of product structure and life cycle characteristics of machine tools, a method for assessing the carbon emissions of machine tools lifecycle was introduced based on the principles of Life Cycle Assessment (LCA). It was used to describe and calculate the carbon emissions of machine tools lifecycle in different stages quantitatively, and the influencing characteristics of life cycle stages was also analyzed. This method divided carbon emission of machine tools lifecycle into four stages, manufacturing, using, transporting and recycling. It also divided carbon emission characteristics into fixed emissions and varied emissions. The linear functions were established. Carbon emission efficiency was proposed to describe changing feature for carbon emission of machine tools. The validity of the method was demonstrated by the calculation and characteristic analysis of carbon emissions combined common numerical control gear hobbing machine tool with a high-speed dry cutting one. Source

Li G.,Chongqing University | Li X.,Chongqing University | Li X.,Chongqing Machine Tool Group Co. | Liu F.,Chongqing University | Sun M.,Chongqing University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering

Since the contact lines between grinding wheel and gear are dynamically changing for form grinding with additional radial motion of topologically modified gear, the calculated wheel profile based on any cross-section of gear will cause a larger grinding error. For reducing grinding error, a method to optimize the profile of grinding wheel is proposed. Firstly, the mathematical models to solve the profile of grinding wheel with additional radial parabolic trajectory is established based on the space engagement theory. Secondly, multiple equidistant plane is used to intercept the gear and to obtain a number of cross-sections for solving the wheel profiles represented with points corresponding to the cross-sections of gear; then a cloud of points is formed by projecting the wheel profiles to a plane, the fitting points of each interval obtained by dividing the cloud into equal intervals is solved based on the least square method, and connecting all the fitting points to form an optimal wheel profile. Given a formula of deviation between actual tooth profile and ideal profile, a mathematical model of gear tooth profile is established based on the meshing condition between wheel and gear to verify the grinding effect of grinding wheel. As an example of axial modified gear, wheel profile both the un-optimized and optimized are calculated, and the results show that the method can be used in the profile calculation of form grinding wheel and effectively reduce the grinding errors of topologically modified gear. © 2011 Journal of Mechanical Engineering. Source

Zhai Y.,Southwest University | Ma X.,Southwest University | Mei Z.,Chongqing Machine Tool Group Co.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering

To overcome the shortages of Al composites reinforced with a single primary Si or Mg2Si particles, a new type of gradient composites reinforced with the two particles was investigated through centrifugal casting. The structures and the properties of the composites have the obvious gradient distribution characteristics. The inner zone is the reinforced zone with a high volume fraction of primary Si and Mg2Si particles, whereas the external zone is the unreinforced zone with few or no primary Si and Mg2Si particles. Due to the high volume fraction of the complementary particles, the hardness values of the inner zone are much more than that of the external zone. The assembling mechanism analysis reveals that the massive primary Mg2Si particles are the key factor to form the gradient composites. In the centrifugal field, the relative velocity of the lower density primary Mg2Si particles is higher than that of primary Si particles. The Mg2Si particles will collide and impel primary Si particles to move more quickly towards the inner zone of tubular parts during freezing, resulting in a strong concentration of the primary Si and Mg2Si particles in the inner zone. To obtain the enough primary Mg2Si particles, the amount of Si should not be lower than 19 wt% and that of Mg not lower than 4 wt% in ternary Al-Si-Mg alloys. © 2014, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved. Source

Li C.,Chongqing University | Li L.,Chongqing University | Cao H.,Chongqing University | Wang Q.,Chongqing Machine Tool Group Co.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering

In view of the uncertainties inherent in remanufacturing process, a fuzzy petri net based remanufacturing process model is proposed to explicitly represent the variations in remanufacturing process routings and process time with respect to product conditions. A fuzzy learning system with an adaptive learning mechanism is designed to estimate the remanufacturing process time of used component under specific conditions, and to dynamically reshape the distributions of actual process time to improve future predictions. The proposed method is illustrated through the remanufacturing of a batch of used lathe spindles with a Matlab-based simulation system. ©2013 Journal of Mechanical Engineering. Source

Li X.-G.,Chongqing University | Li X.-G.,Chongqing Machine Tool Group Co. | Li C.-B.,Chongqing University | Liu F.,Chongqing University | Li L.-L.,Chongqing University
Jisuanji Jicheng Zhizao Xitong/Computer Integrated Manufacturing Systems, CIMS

As the big typical consumer of energy resources, the machine tool manufacturing industry's carbon emission had significance on realization of our country's energy-conservation and emission-reduction. The boundary of carbon emission in machine tool manufacturing process was defined, and the characteristics of carbon emission were also analyzed. A carbon emission model for machine tool manufacturing process was constructed based on Petri net, and the dynamic quantification methods for carbon emission in the manufacturing process were proposed. The proposed methods were applied in a machine tool manufacturing factory, and its carbon emission condition was obtained. Thus the suggestions for energy-conservation and emission-reduction were given. Source

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