游动芯棒拔制显式动力分析

借助ANSYS软件显式动力模块建立了游动芯棒拔制三维有限元模型,动态模拟了游动芯棒拔制的整个过程,根据得到的应力分布规律分析了生产中产生横裂问题的机理。并将拔制力分为四个阶段:起始、初步接触、完全接触、稳定。由于合理配模锥角是游动芯棒是否能稳定在变形区的最显著因素,就此对配模锥角进行了优化,所得结果可为游动芯棒配模锥角选择提供可靠的依据。     

一种用车床加工铝长筒的方法

针对铝质长筒零件,提出了生产中常规的加工方法,通过分析其存在的不足,改进了装夹方式及刀具,得出了更为合理的加工方法.     

The influence of the die and floating plug geometry on the drawing process of tubing

Nowadays, the development of tube drawing process with a floating plug technique has moved our limit up to the production of thick-walled tubes; production of which still belongs to marginal techniques which are different from drawing of standard tubes. The submitted paper is basically a survey of research in fundamental characteristics of tube drawing with a floating plug with the aim to summarize some important results from the theory, which have not yet been published in any English publication. The purpose of this survey is to fill the gap in English literature to promote transfer and exploitation of knowledge. Research in fundamental characteristics was further developed and conditions under which it is possible to draw thick-walled tubes are defined. Confirmed possibility of thick-walled tubes drawing with support provided by a floating plug having negative overlap is the result of theoretical study and practical verification, which enables further moving of drawing process limit.     

A formability index for the deep drawing of stainless steel rectangular cups

The effects of process parameters on the formability of the deep drawing of rectangular cups made of SUS304 stainless steel were investigated by both the finite element analysis method and the experimental approach. A statistical analysis was employed to construct an orthogonal chart which reflects the effects of the process parameters and their interactions on the formability of rectangular cup drawing. The material properties and the forming limit diagram (FLD) of SUS304 stainless steel were obtained from the experiments conducted in the present study and were employed by the finite element simulations. In the finite element analysis, the strain path that led to fracture in the drawing process was examined and the failure modes caused by different process parameters were also identified. With the help of statistical analysis, a formability index for the deep drawing of SUS304 stainless steel rectangular cups was constructed and the critical value of the formability index was determined from the finite element simulation results. The actual drawing processes of rectangular cups were also performed in the present study. The validity of the finite element simulations and the formability index were confirmed by the good agreement between the simulation results and the experimental data. The formability index proposed in the present study provides a convenient design rule for the deep drawing of SUS304 stainless steel rectangular cups.     

Experimental study on multi-stage deep drawing for rectangular cup with high aspect ratio

Multi-stage deep drawing process for rectangular cup using finite element method has been analyzed to understand the main process parameters, to modify the tool configurations for achieving sound intermediate blanks, and to obtain the rectangular deep-drawn cup in the prior study. As shown in the results of the numerical analysis, it has been ensured that the rectangular deep-drawn cup could be obtained. In this study, the tool fabrication and development considering the effects of the intake angle and the ironing operation are performed. The developed tool sets are applied to the multi-stage deep drawing process of this study, and a systematic experiment for the rectangular deep drawing process is carried out. From the first trial in the experiment, several failures are predicted. To solve these failures, the contact surface on the lower die is modified. As shown in the experimental results for the second trial by applying the modified lower die, it is investigated that the failures such as wrinkling and tearing phenomena are not observed, and the excessive deformation behavior due to thinning and thickening effects is decreased. Furthermore, the thickness distributions on the major axis and the minor axis of the intermediate blanks are investigated to be already satisfied by the target (ironing) thickness, respectively. By this systematic approach, it is confirmed that the experimental results show a good agreement with the designed and required configuration of the final product.     

矩形拉深件材料流动变形规律的有限元分析

用有限元模拟矩形盒拉深成形过程并剖析拉深中材料流动变形规律。选用更接近拉深过程本质的动力显式算法和效率更高的壳单元来模拟非回转对称体的成形过程。实验验证了矩形盒成形有限元模拟结果的可靠性。     

The methods of analysis of the process of plug drawing of bimetallic tubing applied to implosively welded composites

Approximate upper bound, force-equilibrium and Shield-type analyses have been modified to account for the effects of friction and strain-hardening in plane strain, plug drawing of co-axially, integrally, welded bimetallic tubing without back-pull. A comparison between experimental and theoretical results indicates that even approximate theories give a reasonably satisfactory measure of agreement; with the upper bound approach being more accurate in the lower range of strains, and the lower bound theories approximating better in the higher range. The Shield-type analysis is preferred because of its ability to indicate the distribution and magnitude of shear stress—in itself an important parameter of the drawing operation.     

Numerical and experimental investigation of pulsating blankholder effect on drawing of cylindrical part of aluminum alloy in deep drawing process

In this study, the effect of a new pulsating blankholder system has been investigated on improving the formability of aluminum 1050 alloy. By using this system, during each pulsating cycle, first, the metal was easily flowed into the die through removing the blankholder force, and then the blankholder force applied by springs was employed to prevent excessive metal flow and wrinkling. Deep drawing of cylindrical cup was simulated by ABAQUS6.7 software. Cup depth, tearing, and thickness distribution of the experimental and numerical analyses were then compared. The results indicated that by using the pulsating blankholder system coupled with proper frequency and gap, the cup depth can be increased and thickness distribution can be improved. Further, good agreement was observed between simulation and experimental results.     

The influence of lubrication in rectangular deep drawing

Rectangular deep drawing is a widely used process in the electrical, automobile, and aeronautical industries, in military engineering, etc. Despite its popularity little information is available about the effect of lubrication on limiting drawing ratio, drawing force, and work done. In view of this, rectangular deep drawing experiments were conducted using mild steel, aluminium, and tin sheets in a 100 t double action hydraulic press. The maximum drawing force, the work done during drawing, and the limiting drawing ratio for a number of commercial lubricants were measured, and are reported in this paper. The effect of anodising has also been studied in the case of aluminium sheets. In the case of mild steel sheets the effect of shot blasting the blank has also been reported.     

Effect of clearance on wrinkling of thin-walled rectangular tube in rotary draw bending process

The clearances between tube and various dies have a significant and complicated influence on the onset of wrinkling during the rotary draw bending process. To study the effect of clearance on wrinkling, a 3D finite element (FE) model of the process for thin-walled rectangular aluminum alloy tube has been built using the explicit code ABAQUS/Explicit and validated by comparing the experiment. Then, simulation and analysis of the process have been carried out based on the model. The influence laws of clearances between tube and various dies on wrinkling have been studied and the reasonable combination of clearances obtained using the combination method of 3D FE simulation and orthogonal experimental design. The results show that with the increase of tube mandrel clearance, Δc _m, and tube bending die clearance, Δc _b, the wrinkling wave number decreases rapidly, whereas the wrinkling wave height increases sharply. The effects of tube wiper die clearance, Δc _w, and tube pressure die clearance, Δc _p, on wrinkling are not significant. The reasonable combination of clearances is Δc _m?=?0.15 mm, Δc _b?=?0 mm, Δc _w?=?0 mm, and Δc _p?=?0 mm. These achievements are helpful to the design and optimization of the process.     

Die shape design of tube drawing process using FE analysis and optimization method

The cold tube drawing has been generally regarded as an effective technology because of its high productivity and low production costs. It has been used instead of the swaging process to form monobloc tube shafts (MTSs) with a constant outer diameter or hollow shafts without defects. MTSs are used nowadays to reduce the weight of shafts and to improve power transmission in the auto industry nowadays. The objective of this study was to design an optimal die that can prevent material fracture considering critical damage value in the tube drawing process. To achieve this objective, a finite element simulation and the flexible polyhedron search method are used. The drawing die shape is represented by the Bezier curve that is able to generate all the possible die shapes. The tube drawing experiments were carried out using the optimized tool. In the experiments, it was possible to produce sound products without fracture.     

盒形件拉深角部变形区的应力解析

盒形件拉深主要变形区集中在盒形件角部的法兰和凹模圆角部位。根据盒形件拉深的特点,假设盒形件圆角区剪应力零线与圆筒形拉深件的变形规律相同,通过理论推导得到了盒形件角部变形区法兰和凹模圆角处的应力解析表达式,为定量研究盒形件拉深成形提供了理论依据。     

Study on process parameters and its analytic application for nonaxisymmetric rectangular cup of multistage deep drawing process using low carbon thin steel sheet

Multistage deep drawing process is widely used to obtain various nonaxisymmetric rectangular cups. This deep drawing scheme including drawing and ironing processes consists of several tool sets to carry out a continuous production within one progressive press. To achieve the successive production, design and fabrication of the necessary tools such as punch, die, and other auxiliary devices are critical, therefore, a series of process parameters play an important role in performing the process design. This study focuses on the tool design and modification for developing the rectangular cup with an aspect ratio of 5.7, using cold-rolled low carbon thin steel sheet with the initial thickness of 0.4 mm. Based on the design results for the process and the tools, finite element analysis for the multistage deep drawing process is performed with thickness control of the side wall in intermediate blanks as the first approach. From the results of the first approach, it is shown that the intermediate blanks could experience failures such as tearing, wrinkling, and earing by excessive thinning and thickening. To solve these failures, the modifications for the deep drawing punches are carried out, and the modified punches are applied to the same process. The simulation results for the multistage rectangular deep drawing process are compared with the thickness distributions before and after the punch shape modifications, and with the deformed shape in each intermediate blank, respectively. The results of finite element reanalysis using the modified punches show significant improvement compared with those by using the original designed punch shapes.     

Research on cross-sectional deformation of double-ridged rectangular tube during H-typed rotary draw bending process

Based on the ABAQUS/Explicit, a three-dimensional elastic–plastic finite element model of the H96 brass double-ridged rectangular tube (DRRT) during H-typed rotary draw bending (RDB) was established and its reliability was validated by an experiment. With the model, distribution characteristic of cross-sectional deformation and effects of clearance and friction coefficient between tube and dies and core number on it were studied. The results show that the maximum cross-sectional height distortion ratio appears at the bending angle 60°. And the maximum cross-sectional width distortion ratio between side walls, as well as side walls of the ridge grooves, appears at the bending angle 80° and 60°, respectively. In addition, retracting mandrel has a great effect on the cross-sectional height distortion, but its influence on the cross-sectional width distortion can be ignored. And the maximum cross-sectional distortion ratio initially increases with increasing of clearance between tube and mandrel c _m and friction coefficient μ _b between tube and bending die, and then decreases with their increase, and initially decreases with the increase of core number N, and then increases with increasing of N. Moreover, the reasonable value of N is taken as 4.     

Relations between the stress components and cross-sectional distortion of thin-walled rectangular waveguide tube in rotary draw bending process

The significant cross-sectional distortion is one of the major problems in the bending of thin-walled rectangular waveguide tube. The cross-sectional distortion, which contains the flange distortion and the web distortion, depends on the stress components distribution. In this paper, the cross-sectional distortion characteristics are investigated using a three-dimensional finite element (FE) model. Results show that: the maximum flange distortion locates at the symmetric line; meanwhile, the maximum web distortion locates at the extrados ridge of the tube. The deformation zone of the tube can be divided into three sub-zones considering the loads and deformation, viz., the clamp die affect zone, the middle zone, and the mandrel/cores affect zone. Then the underlying relations between the cross-sectional distortion and the stress components are obtained. It is found that the flange distortion has a close relation with the circumferential stress. At the same time, the web distortion is relevant to both the tangential and the circumferential stress. The above relations are verified by FE models with different cores number. Moreover, some guidelines are introduced to help reduce the cross-sectional distortion.     

Deep drawing with internal air-pressing to increase the limit drawing ratio of aluminum sheet

The effects of internal air-pressing on deep drawability are investigated in this study to increase the deep drawability of aluminum sheet. The conventional deep drawing process is limited to a certain limit drawing ratio(LDR) beyong which failure will occur. The intention of this work is to examine the possibilities of relaxing the above limitation through the deep drawing with internal air-pressing, aiming towards a process with an increased drawing ratio. The idea which may lead to this goal is the use of special punch that can exert high pressure on the internal surface of deforming sheet during the deep drawing process. Over the ranges of conditions investigated for Al-1050, the local strain concentration at punch nose radius area was decreased by internal air-pressing of punch, and the deep drawing with internal air-pressing was proved to be very effective process for obtaining higher LDR.     

Analysis of the allowable deep drawing height of rectangular steel parts

This paper presents a theoretical, numerical and experimental analysis of the allowable (maximum) deep drawing height (DDH) of rectangular cups made of steel. In particular, a new expression to calculate the allowable DDH of rectangular deep drawing, based on the equivalent diameter concept and the volume conservation principle, is proposed and compared with those theoretical expressions currently available in the literature. Finite element method simulations together with experimental data taken from a set of 20 industrial steel parts are used to evaluate the accuracy of each theoretical expression. The results have shown that the new expression has superior precision than those existing in the literature.     

A new control system for auto-leveling of high speed drawing frame

According to the characteristic of high speed drawing frame auto-leveling: open loop can avoid the dead zone, but can’t ease or eliminate the influence of disturbance; close loop can reduce the influence of disturbance, but can’t avoid the dead zone, under the influence of disturbance model is hard to build; and high speed of drawing frame has high demand on hardware and software. Based on new hardware architecture a new auto-leveling control system with mixed loop and fuzzy method is put forward, in which open loop is designed to get the basic control value and close loop inferring from fuzzy control rules to get the increment value and decrease the influence of disturbance by correcting the basic control value obtained from open loop. In conclusion, experiment in FA398 proves the applicability of this system for auto-leveling of high speed drawing frame.     

Particle swarm optimization for achieving the minimum profile error in honing process

Gears are among the most important mechanical components of the modern industry. The topography of the gears’ tooth flank has an intricate and complex form and requires great finishing and quality. Commonly, traditional grinding processes are applied to finishing gear profile. However, the use of honing process has grown in recent years to provide the best finishing in industrial products. In this study, the honing process was improved applying a particle swarm optimization. Pinions of steering systems were used as work pieces to testify the optimization technique. The input parameters were the spindle speed, feed rate in X direction, feed rate in Z direction, oscillation time, and spark out time. The experimental measures were compared with simulation tests using the responses total profile deviation (f_α), total helix deviation (f_β), and total cumulative pitch deviation (f_p). The results showed that profile error was minimized, and the quality was improved based a set of strategies that were held simultaneously in the input parameters.