共查询到20条相似文献,搜索用时 31 毫秒
1.
《Tribology International》2012,45(12):1742-1753
This paper aims to utilize finite element (FE) methods to predict the wear of dies and workpiece in cold rotary forging through systematically investigating the contact pressure and the contact slip distance. For this purpose, a 3D elastic-plastic FE model of cold rotary forging is developed using the FE code ABAQUS. Using this reliable 3D FE model, the evolution and the distribution of contact pressure and contact slip distance are investigated in detail. Consequently, a new insight into the wear that occurs at the surfaces of the dies and the workpiece is gained based on Archard's wear law. 相似文献
2.
Investigating the contact pressure response in metal forming is significant for effectively predicting the die wear and controlling the metal flow of the workpiece. This paper is aimed to utilize FE methods to reveal the contact pressure response in a complicated metal forming technology of cold rotary forging. For this purpose, a 3D FE model of cold rotary forging is first developed. Then, the contact pressure is numerically calculated. Finally, the effect of the process parameters on the contact pressure response is revealed. More importantly, the relationship between the contact pressure response and metal flow of the workpiece is clarified. 相似文献
3.
Xinghui Han Lin Hua 《The International Journal of Advanced Manufacturing Technology》2012,62(9-12):1087-1106
Cold rotary forging is an advanced but very complicated metal plastic forming technology with continuous local plastic deformation. Investigating the contact parameters between the contact interactions has a great importance to improve the contact performance. This paper is aimed to utilize the finite element (FE) method to study the contact parameters in a complex continuous local forming technology of cold rotary forging. For this purpose, a reasonable 3D elastic–plastic dynamic explicit FE model of cold rotary forging of 20CrMnTi alloy is developed using the FE software ABAQUS/Explicit. Based on this valid 3D FE model, some important contact parameters, such as the contact pressure, contact slip rate, contact slip distance, and contact force, are numerically examined in detail. The results of this research help to better understand the complicated contact mechanisms in cold rotary forging. 相似文献
4.
Cold rotary forging is an innovative incremental metal forming process, which is obviously different from the conventional
forging process in many aspects, such as the metal flow, degree of inhomogeneous deformation of workpiece and force and power
parameters. In the current work, a 3D elastic-plastic dynamic explicit FE model of cold rotary forging of a cylindrical workpiece
is developed under the ABAQUS software environment and its validity has been verified by the experiment. Based on the reliable
3D FE model, the cold rotary forging and conventional forging process are simulated and their difference in the forming process
has been thoroughly clarified. The research results may help to understand the cold rotary forging process better. Furthermore,
they provide valuable guidelines for further theoretical analysis and experimental studies on the cold rotary forging process. 相似文献
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The bending moment transmitted to the forging manipulator due to press motion during metal forming process is investigated. The dynamic model of the forging manipulator system is established, including the manipulator and the workpiece by using Lagrange equation. The system is modeled as an Euler-Bernoulli beam with spring-mass at the sliding end, which experiences a transient vibration due to displacement excitation. The Winkler foundation model is used to simulate the rotational constraint of the forging dies on the workpiece because of the surface contact. The numerical results are compared with the LS-DYNA simulations, and a good prediction on the bending moment could be obtained with the comparatively simple proposed model. The results indicate that the press position where the forging dies work along the workpiece plays a crucial role for the dynamic bending moment. To further investigate the dynamic effects due to the press motion, the influence of clamp mass of the manipulator is also examined. 相似文献
8.
汽车前轴精密辊锻成形过程的数值模拟 总被引:13,自引:1,他引:12
汽车前轴的精辊-模锻工艺是一种用小成形力锻造设备成形较大型前轴锻件的塑性加工技术,其工艺关键在于精密辊锻。前轴的精密辊锻分4个道次,是典型的局部成形工艺。辊锻工艺由于旋转的模具与辊锻件之间的接触区域在不断变化,一直以来成为数值模拟的难点。对4个道次的模具建立了模型,采用三维刚塑性有限元程序DEFORM-3D模拟了前轴精密辊锻工艺,分析了辊锻过程中金属变形的规律,研究了模具参数对成形质量的影响以及辊锻力矩的变化规律。模拟结果对于改进辊锻工艺设计、提高模具设计水平具有指导作用。 相似文献
9.
In rotary forging the rocking motion of the upper die results in an instantaneous die contact area which is only a small proportion of the total billet area. Forming forces are thereby reduced to a fraction of the uniaxial forging force. Most analyses developed for force prediction calculate the contact area between the rocking die and the billet without considering the effects of elastic distortion of the dies. In this paper it is shown that elastic distortion results in a substantial increase in contact area and force when cold forging hard metals, particularly when the rocking angle is small. Experimental results taken over a range of test conditions give reasonable correlation with the simple theory.The analysis and experiments are concerned with the upsetting of circular cylindrical billets, but it is considered that the conclusions apply to other component forms. 相似文献
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A.K. Singh 《Wear》1973,25(2):271-279
Simple upsetting tests were used to assess the wear of hot forging dies. The influence of forging variables such as die-billet contact time and lubrication is described. A “white” layer is formed at the surface of lubricated dies when die-billet contact times exceed 5 ms. This layer was identified as martensite of increased wear resistance. Lubrication affects the frictional condition at the die-billet interface thus facilitating the relative movement of the billet material over the die surface resulting in the increased wear of flat dies. 相似文献
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Aditya T. Kasarekar Nathan W. Bolander Farshid Sadeghi Spyros Tseregounis 《International Journal of Mechanical Sciences》2007,49(6):690-703
This paper presents a numerical model that maps the evolution of contact pressure and surface profile of Hertzian rough contacting bodies in fretting wear under partial slip conditions. The model was used to determine the sliding distance of the contacting surface asperities for one cycle of tangential load. The contact pressure and sliding distance were used with Archard's wear law to determine local wear at each surface asperity. Subsequently, the contact surface profile was updated due to wear. The approach developed in this study allows for implementation of simulated and/or measured real rough surfaces and study the effects of various statistical surface properties on fretting wear. The results from this investigation indicate that an elastic–perfectly plastic material model is superior to a completely elastic material model. Surface roughness of even small magnitudes is a major factor in wear calculations and cannot be neglected. 相似文献
13.
U. Ince M. Güden 《The International Journal of Advanced Manufacturing Technology》2013,68(9-12):2133-2144
A set of temperature-dependent friction coefficients was developed to increase the accuracy of finite element (FE) simulations of cold bolt forging. The initially attained friction coefficients at different temperatures were calibrated with the iterations between the experimental and thermomechanical model extrusion test loads. The constant friction coefficient and the determined set of friction coefficients as function of temperature were then implemented to the simulations of the cold bolt-forging processes. Further calibrations and model validations were made based on the temperature measurements of the workpiece in the actual bolt-forging processes. To show the advantages of developed temperature-dependent friction coefficients, the loads of four different bolt-forging processes were compared with the thermomechanical model loads calculated using the constant friction and temperature-dependent friction coefficients. The modeling results indicated that the use of temperature-dependent friction coefficients in the FE simulations resulted in nearer temperature distributions and the loads of the workpiece during forging as compared with the use of a constant friction coefficient. 相似文献
14.
A new piezo-viscous, average flow model combined with an advanced slab method is used to investigate the lubrication in axisymmetric forging processes with flat dies. Interactions between lubricant transport and surface roughness are studied. Influence of friction on the outward motion of the workpiece is also considered. It is shown that the lubricant is transported outward in a speed slower than half the surface speed, and the film thickness is smaller than the case of the smooth surface if asperity contact is not severe. However, when asperity contact is pronounced, the lubricant pressure distribution is quite different from the prior research. Mixed lubrication is observed in most of the region where asperity contact occurs. Boundary lubrication can only be found in a narrow area near the workpiece edge. 相似文献
15.
高筋薄板构件多自由度摆动辗压成形过程中金属流动十分复杂,导致高筋薄板构件筋高分布十分不均匀。根据双偏心套型摆动辗压机运动原理,探究摆动模做圆轨迹和螺旋线轨迹运动时摆动模与坯料的接触模式演化规律,提出了接触区形状数学计算方法。采用有限元模拟仿真技术揭示摆动模做圆轨迹和螺旋线轨迹运动时高筋薄板构件摆动辗压成形金属流动规律以及高筋生长规律,阐明摆动模运动、接触区变化、金属流动和高筋生长之间的关联关系。在此基础上,开展高筋薄板构件摆动辗压成形工艺试验,实现高筋薄板构件摆动辗压成形。研究结果表明,相比圆轨迹运动,摆动模做螺旋线轨迹运动能够减弱金属径向和切向流动,增强金属轴向流动能力,从而有效提高高筋薄板构件摆动碾压成形过程中金属轴向流动的均匀性,获得筋高分布均匀的高筋薄板构件。 相似文献
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Yohng-Jo Kim Chang-Hyok Choi 《International Journal of Precision Engineering and Manufacturing》2009,10(3):105-113
In this study, the forging die life was investigated using fatigue life and wear quantity, which are generally considered
for estimation of die life. The main aim is development of the equations to adapt finite element analysis to life estimation
for a hot forging die. The Archard’s model was used to estimate the wear life of the die and Goodman’s and Gerber’s equations,
using the stress-life method, were applied to estimation of the fatigue life. These techniques were applied to die life estimation
for the hot forging die of a ball joint socket used in an autovehicle system. Rigid-plastic finite element analysis was first
carried out for the forging process of the ball joint socket and then the elastic stress analysis was performed for the die
in order to obtain fundamental data for the prediction of fatigue life. The die stress analysis requires the deforming loads
of the workpiece to be translated into the contact loading of the die. In this case, the size of finite elements of the die
and the workpiece is important for good interpolation of the loading. Therefore, the influence of element sizes on the interpolation
results of the contact loading was also investigated. The wear volume of the die was measured using a 3-dimensional scanner
of probe type. It was found that the measurement had a good agreement with the results of the finite element analysis for
the die life estimation. 相似文献
18.
The use of coolant has been considered an effective way to avoid workpiece burn in the grinding process. Hydrodynamic pressure induced by coolant in the contact zone is always measured to characterize the coolant condition in the contact zone. In this study, grinding experiments with a cubic boron nitride wheel were first performed to determine the evolution of hydrodynamic pressure during the grinding process. The experimental results showed that when burn happened, hydrodynamic pressure was at a low level and decreased gradually while the temperature and power signals fluctuated sharply. A theoretical calculation model and a 3D air–liquid two-phase numerical simulation model were subsequently constructed to predict the hydrodynamic pressure. Both theoretical calculation and numerical simulation results showed that the hydrodynamic pressure in such a case is in inverse proportion to the gap distance between the wheel and the workpiece. The theoretical calculation results are higher than the numerical simulation results. Furthermore, the experimental results correspond to the results of the 3D air–liquid two-phase simulation, which confirms the validity of this simulation. This article presents an accurate approach to predict hydrodynamic pressure, which provides an effective analytical method of studying and avoiding workpiece burn. 相似文献
19.
Gears in precision mechanisms, such as industrial robots, are often designed to have no backlash. Deviations from the ideal gear geometries and unfavourable deformations during operation may cause interference between interacting tooth flanks, resulting in high and strongly varying friction. Mild wear of the tooth flanks may improve such conditions. Therefore, this theoretical study has been conducted of wear in spur gears with interference. A mixed finite element (FE) and analytical approach is used. The FE method is used to determine contact loads between the interacting gear teeth. The main drawback with FE analyses of this type of problem is normally the computation time needed. Therefore, a novel FE meshing method is used, giving a dense FE mesh in the contact regions and a coarse mesh in the rest of the teeth. Based on the FE determined loads between the interacting teeth, the contact pressures and the contact widths are then easily determined using analytical expressions based on Hertz theory. The wear of a point on a tooth flank is determined by integrating the product of sliding distance and contact pressure during the time it is in contact with its mating flank.The results show that the wear of the gear tooth flanks may eliminate the interference and consequently the high and strongly varying friction will decrease dramatically. However, the transmission error will change, since the gears will not preserve their accurate involute profiles. 相似文献
20.
Tribological phenomena, i.e. friction, tool wear and material pick-up to the tool, in metal forming processes are influenced by various factors. Therefore, in friction tests in the laboratory, these factors should be varied widely and independently and they should be measured easily. A new test method which has these features is described; the test parameters are the tool pressure, sliding speed, enlargement of the workpiece surface, length of contact between the tool and workpiece, sliding distance, contact angle and viscosity of the lubricant. Some results of the tests on tool wear are presented and discussed. 相似文献