Advanced Materials Research Vols. 291-294

Abstract: Control of the motion process of acceleration/deceleration (Acc/Dec) is one of key complicated problems in CNC system development. The excellent Acc/Dec control can improve the processing precision. The traditional Acc/Dec algorithms such as the linear and the exponential are not suitable for high speed motion because there would be flexible impacts existing in feed motion, especially that the jerk of the S-shape curve Acc/Dec is discontinuous. A new flexible Acc/Dec algorithm for high speed motion system based on the squared sine function is introduced. The modeling of the Acc/Dec algorithm with Trigonometric Function Squared Sine(TFSS) shape curve is constructed.In this algorithm, the sine curve in jerk, acceleration, velocity and displacement are all continuous. The simulation experiments result demonstrate that the Acc/Dec algorithm with TFSS shape curve is a new method of continuous Jerk for the design flexible Acc/Dec.

Abstract: FEM simulation of aluminum profiles in porthole die extrusion process using Lagrange mesh description will inevitably bring mesh self-contact, severe grid distortion and frequent remeshing, which will result in the loss of computational accuracy and excessive calculation time. In order to solve the above mentioned problems, numerical simulation of aluminum profiles with large and complicated cross-section in extrusion process was achieved using finite volume method based on Euler mesh description. The metal flow behavior and welding course was investigated in detail, which can provide the theoretical guide for porthole die design and optimization. In addition, extrusion experiment was carried out by numerical simulation results. The experimental extrudate was in good agreement with the simulation results, which laid a good solid foundation for non-steady state extrusion process analysis of large scale and complicated cross-section profiles.

Abstract: Cold ring rolling is a kind of advanced manufacturing technology. During rolling process the ring may be collapsed or deformed unexpectedly under the pressure of guide roll because the stiffness condition is not met. The force of guide roll to ring was obtained by analyzing the forces to ring. The stiffness condition expressions of ring during rolling were shown after constructing the mechanical model. According to the expressions, the effects of several parameters on the stiffness condition were discussed and analyzed in detail, such as position angle of guide roll, friction coefficient and feed rate, etc, which revealed essential reasons of some cases occurring in cold ring rolling. Then the ring blank dimension was deduced based on the ring stiffness condition. The dimensions of ring blank should meet a relationship to ensure the ring stiffness condition to be satisfied during rolling, which can conduct the practical manufacturing effectively. Finally the analysis and effect laws were proved by finite element simulation experiments. The researches could be helpful to control parameter in cold ring rolling effectively for high quality products.

Abstract: The 3003 Al alloy was deformed by isothermal compression in the range of deformation temperature 300-500 °C at strain rate 0.0l-10.0 s^-1 with Gleeble-1500 thermal simulator. Processing maps at a strain of 0.6 for hot working were developed on a dynamic materials model. The maps exhibit a flow instability domain at about 300 °C-380 °C and 1.0-10.0 s^-1. DRX occurs extensively in the temperature range of 450-500 °C and at the strain rate of 10.0 s^-1. The optimum parameters of hot working for 3003 Al alloy at the strain of 0.6 are confined at 500 °C and 10.0 s^-1 with the highest efficiency (37%).

Abstract: Flow stress data is important base data in using the analytical method and the finite element method to analyze the metal cutting process.In the present study, a comprehensive method combining with four methods of material mechanics tests, SHTB impact tests, two-dimensional orthogonal slot milling experiments and reverse solving is used to determine constitutive model (flow stress model) as a function of the "three-high" (high strain , temperature and strain rate) in metal cutting. The constitutive model of 20CrMnTi gear steel (hardened to170±5HB) which is one of China’s main gear steels in cutting deformation is established by using this method, and experimental results show that the model’s accuracy is high. Practice has proved that the methodology of constitutive model determination for metal cutting deformation, proposed in the present study, has advantages when compared with using one method alone, and is more suitable to establish flow data for the various materials in the metal cutting process.

Abstract: This paper describes the structural optimization technique with FEM topography optimization technology, the design shape of engine components have been optimized based on the sensitivity analysis, and the purpose is to minimize the vibration of engine block. The process of structural optimization display that the vibration on FEM models of engine block as boundary conditions for subsequent topography optimization were used to be an output from dynamic response analysis, and the loads exerted on the FEM models are acquired from the multibody dynamics system, and topography optimization is performed to detect the effective design parameters of engine block shape to structural strength, to reduce the vibration velocity intensity. This paper presents today’s computer design capabilities in the simulation of the dynamic and vibration behaviour of engine and focuses on the relative merits of modification and full-scale structural optimization of engine, together with the creation of new low-vibration designs. The results verify the analysis, assessment and vibration optimization of the engine.

Abstract: The multifactor coupling simulation analysis of alien wheel forming process was performed. As for preforming and final-forming process the metal flowing, the temperature field of dies and billet were analyzed. The temperature varying and heat loss were forecast. Based on archard wear model the single-step wear depth in multifactor coupling conditions was evaluated, which helped to evaluating die life. The process scheme according to simulation results got good test verifying.

Abstract: Process planning and scheduling are two important manufacturing activities in the manufacturing system. In this paper, an improved genetic algorithm(GA) has been developed to facilitate the integration and optimization of process planning and scheduling. To improve the optimization performance, an efficient genetic representation has been developed. Selection, crossover, and mutation operators have been described. Simulation studies have been established to evaluate the performance of the algorithm. The results show that the algorithm is a promising and effective method for the integration of process planning and scheduling(IPPS).

Abstract: According to the shape character of some one automobile inner panel of front fender the forming steps characterized by some process combined was brought forward. Based on FEM software the drawing process was simulated by a blank-holder force scheme 100000N, 200000N, 300000N. As the simulation results, in order to eliminate the fractures in diagonal reinforcements, it is infeasible only to decrease blank-holder force, but enlarging the die round corner is necessary. As fractures have been eliminated, in order to eliminate wrinkles, the blank-holder force needs to be increased. Otherwise the wrinkle region can be confined into useless area which needs to be cut off. Finally none forming defects occur as blank-holder force 300000N and die round corner 5mm.

Abstract: For combed spun yarn of high quality, the feed amount per cycle and the bat weight have to be chosen correctly. When the feed amount per cycle and the bat weight are too low or too great, there is an effect on the combing efficiency, piecing quality, percentage of noil and quality of spun yarn. The influence of the feed amount per cycle and the bat weigh on combing efficiency, percentage of noil and piecing quality are analyzed theoretically. In order to investigate the effects of the feed amount per cycle and the bat weight on yarn quality (unevenness CV%, thin places, thick places and neps), The 14.6 tex yarn is spun on combing spinning system with E62 comber. The results of our investigations reveal that high combing efficiency and high quality yarn can be obtained with a lesser feed amount per cycle and a bigger bat weight on new type of cotton comber.