Applied Mechanics and Materials Vols. 130-134

Abstract: The stability of mold oscillation can directly influence on slab surface quality and operational safety in continuous casting. In recent years, the hydraulic oscillation is developed and applied as the driven equipment of mold oscillation. In the present work, based on the slab continuous caster of hydraulic oscillations, the displacement and other parameters of hydraulic oscillator are measured and the evaluation method of oscillation is studied. The displacement difference and phase difference of oscillation with sinusoidal waveform and non-sinusoidal waveform are analyzed. Especially, the dynamic characteristics of the driving force of left and right cylinders are evaluated. The results indicated that the hydraulic oscillator is quite a good device in terms of precision. The method proposed may be useful for evaluating oscillators.

Abstract: The crossbeam is an important part in the gantry machining center which greatly affects the machining accuracy. Four kinds of crossbeam structure for the large machining center were designed and their static and dynamic characteristics were analyzed. The optimal crossbeam structure was selected by the comprehensive performance evaluation method. Then the thicknesses of rib plates in the crossbeam were defined as the optimization parameters after conducting the sensitivity analysis. The first four natural frequencies were defined as the objective functions and the static performance and the mass were defined as the constraint conditions. The optimal sizes of the rib plates in the crossbeam were obtained by the optimization analysis. Finally the feasibility of the result was demonstrated by the simulation. The result indicated that with the mass increased only by 0.18%, the first four natural frequencies of the optimal crossbeam were increased by 19.56%, 19.45%, 19.84%, 17.05%.

Abstract: The energy consumption for manufacturing processes is the largest impact contributor in various characterization categories, based on the assessment of environmental effects during the whole life cycle. It is necessary to investigate the manufacturing processes in depth to find out mechanism that can improve energy efficiency. This paper presents a comprehensive overview on two important aspects of energy consumption models for manufacturing processes: 1) two data collection methods: top-down and bottom-up; 2) two process-based analytical methods: thermodynamic model (including energy flow analysis and exergy analysis), and mechanical model. These models can improve energy efficiency.

Abstract: Based on the influences of eccentrical rotating inertial centrifugal force and axial force on the rod string’s lateral bending deformation, the finite beam element model of rod string’s bending deformation is established. The constraint to rod string’s bending deflection exerted by inwall of circular tube and the distinction of the constraint to rod string’s deflection because of the different gaps between rod string to circular tube and coupling to circular tube are both taken into account. Meanwhile, removable spring elements with two directions are adopted, by which the non-linear contact problem between the rod string and circular tube is well resolved. Combining space beam element and spring elements with two directions, the corresponding finite element simulating program is also developed. Several simulating results can be shown as follows: eccentric rotation of rod string is able to produce gyro effect in vertical circular tube; The shape of the rod string’s deformation is a spiral which is thin on the upper-part and dense on the under-part; Gyro wave numbers are affected obviously by rotating speed, eccentricity, axial concentrated force, axial distributed force and length of the rod string.

Abstract: Based on the structural bionic method, the rotary worktable of vertical lathe was optimized. Through fuzzy similarity analysis, the similarity of the bionic prototype and the rotary worktable was obtained, and the rationality of the bionic prototype was verified. According to the bionic prototype, the optimization model was established. Then it was transferred into the Workbench of the ANSYS to be analysed by the finite elements method. Comparing with the prototype, the results indicate that the bionic worktable’s mass reduces 280kg, and the deformation reduced 4.7%. The first five natural frequencies of bionic worktable increased. The results show that the bionic rotary worktable is more reasonable. It offers a new solution to optimize the rotary worktable of various vertical lathes.

Abstract: According to the theory of contact mechanics, the radial stiffness, the maximum contact stress, and the maximum radial load of pre-loaded cylindrical roller bearings, including both solid roller and hollow roller bearings, are calculated with the finite element method. The effects of load on the radial stiffness, the maximum contact stress, and the maximum radial load of bearing are analyzed. The analysis results show that the effect of load on the radial stiffness is complex. Under the different magnitude loads, the effects of both hollowness and interference magnitude on the radial stiffness and on the maximum contact stress are not same. Thus the effects of load magnitude must be considered in the design and application of pre-loaded cylindrical roller bearings.

Abstract: Based on profile involutes equation and tooth easement curve equation of standard gear, parameterization three dimensional finite element model of the gear drive system is built up in ANSYS, and numerical computation of the working process is taken in ANSYS/LS-DYNA, then contact stress of and pressure distribution are got. It creates an ultimate state equation of every system parameter (input) converting to output (response), considering different system random error synthetically, sample points locations in input variable sampling space are fixed with the method of matrix experiment design, which was used in series of deterministic fitting test. In the test, least-squares procedure regression analysis of the ultimate state equation is taken to fix the items and coefficients after multiple fitting test. Using this ultimate state equation, system reliability level and reliability sensitivity of different variables can be calculated which provides theoretical bases for dynamic optimum design of gear drive system.

Abstract: NC machine plays an irreplaceable role in the modern manufacturing because of its high machining processing accuracy, quality stable, flexibility. Through using the Renishaw ML10 laser interferometer detect the positioning accuracy and repositioning accuracy of X axis and Z axis of the HTC20 series of NC machine tools. According to the detection result compensate NC system to meet the machining accuracy requirement. The result shows that the error compensation of NC system is a effective method to improve the position accuracy of NC machine.

Abstract: In this paper, objective design phase for beginning end of product design process is studied and the procedures and steps of object design is described. Sources of finding design objects and methods, information collection and processing of design object are studied. Simultaneously, several criterions are designed to judge feasibility of design object, such as social environment criterion, economic cost criterion, technology criterion, time criterion, value criterion etc.. Computer aided screening and evaluation is realized during objective design. Finally, the template of expressing design object is given.

Abstract: In order to get high quality forgings, it is significant to predict the microstructure evolution during hot forging process accurately. In this study, a simulation model is built by combining FEM with the dynamic recrystallization model of 42CrMo, and the finite element model is proved to be reliable by a serial of upsetting deformation experiment. Then the distributions of microstructure evolution are obtained on upsetting process. Upsetting is beneficial to refine the grain size and drawing can make the distribution of grain size homogeneous. By comparing the simulation results with experiments, the distributions of microstructure are a close match in the middle part of steering arm. The forgings formed by this process have a good microstructure and have high comprehensive mechanical properties.