Shape Drawing Process Research Articles

Design of an Intermediate Die for the Multi-Pass Shape Drawing Process.

The multi-pass shape drawing process is mainly used in metal forming processes to manufacture long components with constant arbitrary cross-sectional shapes along their lengths. The cross-roller guide is a typical component that is manufactured by a multi-pass shape drawing process. The cross-roller guide is mostly used in optical measurement equipment where high-precision movement is required. Therefore, the dimensional accuracy of the cross-roller guide is very important since it can influence precision linear motion. However, the unfilled defects can occur in a case where the product has a complex cross-sectional shape. In this study, a new design method for an intermediate die is suggested by using an equal-radial-velocity variation method in order to reduce the unfilled defects. The proposed design method can reduce the unfilled defects by minimizing the radial velocity variation in the deformation zone of the drawing die. The intermediate die was designed by geometrical information of the final product without prior finite element (FE) analysis. The suggested method was applied to design the multi-pass shape drawing process for manufacturing the cross-roller guide. FE analysis was performed to validate the effectiveness of the proposed method in comparison to the conventional design method that uses equipotential lines in the multi-pass shape drawing process. Finally, a shape drawing experiment was performed to compare the target shape and the FE analysis with the experimental data.

New tandem drawing process through non-driven four roll-die and converging die

In the past decades, drawing processes have been applied to industries worldwide by employing several new solutions. In the case of drawing using conventional dies in tandem, it is widely-known that the deliberate application of back-pull can contribute to the improvement of die life and reduction in die load. To a certain extent, back-pull is present in the drawing process because the drawing force in the preceding stand tends to act as a back-pull in the next drawing stand. In the case of drawing by using a non-driven roll-die, deformation occurs between the roller pairs without the driven rolls. The drawing process using a non-driven roll-die can lead to a decrease in friction. The drawing process using a roll-die consumes lower power in comparison with other processes, owing to the decrease of friction.In this study, a multi-roll-die drawing (MRD) process, which is a new tandem drawing process through a non-driven four roll-die and converging die, is proposed to reduce the drawing force. The MRD was evaluated by being compared with the multi-die drawing process (MDD). First, a prediction model of the drawing force based on Geleji’s equations and the cross-sectional method was used. Additionally, the contact areas of the converging die and roll-die were modified for the shape-drawing process. The drawing force of the process through two dies in tandem was evaluated by being compared with the drawing force of a conventional drawing process. Subsequently, finite element (FE) simulations were performed to predict the drawing force in each process. They were used to verify the calculated drawing forces of the MDD and MRD processes. Moreover, experiments with regard to the MDD and MRD processes were performed to verify the predicted drawing forces. The predicted results were compared with the experimental results. Thereby, it was found that the predicted drawing force was in good agreement with the experimentally measured force. The drawing force reduction in the MRD process was evaluated by being compared with that of the MDD process. To investigate the effect of each process, numerical simulations, and Vickers micro-hardness tests were conducted, and their results were compared.

A Four-Roll Squeeze Pointing Machine for a Shape-Drawing Process

A pointing process is a pre-work operation to facilitate the feeding of a rod to pass through a drawing die. After performing the pointing process, the drawing material is inserted into the drawing die and the jaw pulls the end of the material. A bar pointing turning machine, which is universally used for the pointing process, causes a breaking of drawing material easily in the shape-drawing process. Because a shape-drawing process requires a higher drawing load and a smaller cross-sectional area of the pointed zone of drawing material, a pointing process which is to prevent the breaking of the drawing material through a work-hardening effect at an early stage of the drawing process is necessary. In this study, a four-roll squeeze pointing machine (RSPM) as a new automatic pointing machine is introduced. RSPM has been developed to improve the productivity of the pointing process as well as the shape-drawing process by preventing the breaking of the drawing material. The ductile fracture criterion based on Cockcroft–Latham’s theory was used to predict the breaking of drawing material and any defects during the pointing process. A tool design method for the RSPM and a feasible pointing size for the conventional pointing machine are proposed. In addition, the drawing materials manufactured using a conventional pointing machine and the RSPM are compared through finite element (FE) simulations and experiments.

A new method for predicting drawing load of shape drawing process

The shape drawing process is a very useful metalworking process that can produce an elongated component with a constant cross-sectional shape. The prediction of drawing load is critical for evaluating the potential of shape drawing. However, it is challenging to predict the drawing load of shape drawing because of the complex cross-sectional shape of the drawn material. In this study, a new theoretical method is proposed to predict the drawing load of shape drawing. The proposed method is based on the geometric division of the cross section and an axisymmetric drawing load prediction model. The drawing loads of square and hexagon shape drawings from round material are predicted by using the proposed method. The effectiveness of the proposed method is verified through finite element analysis and a shape drawing experiment.

중공형 LM-Guide Rail의 치수정밀도 향상을 위한 형상인발 금형 설계

Multi-pass shape drawing is used to manufacture long products of arbitrary cross-sectional shapes. This process allows smooth surface finishes and closely controlled dimensions of the cross-sectional shape. Tube shape drawing for hollow type products provides material savings and weight reduction. The intermediate die shapes are very important in multi-pass tube shape drawing. In the current paper, the design method for the intermediate dies in a tube shape drawing process is developed using a die offset for corner filling (DOCF) method. Underfill defects are related to the radial velocity distribution of each divided section in the deformation zone. The developed intermediate die shape design was applied to the two-pass tube shape drawing with fixed mandrel for manufacturing a hollow linear motion (LM) guide rail. The proposed design method led to uniform and steady metal flow at each divided section. FE-simulations and experiments were conducted to validate the effectiveness of the proposed method in multi-pass tube shape drawing process.

DRAWING OF SOLID REGULAR POLYGONAL SECTION SHAPES

In designing the regular polygonal section shape drawing process, it is convenient to use analytical expressions allowing us to estimate effectively the effect of different process factors. A design procedure of stress calculation for this process is proposed. The ratios for calculation of drawing stress, optimum angle of the drawing tool hole, limit value of deformation degree in using the standard tool and index of stress state in the axial part of the deformation zone are obtained. The use of drawing tools with optimum angles reduces the accumulation rate in the metal structure and in case of repeated drawing allows us to cut down the number of intermediate heat treatments.

인발응력을 고려한 다단 형상인발 공정설계

In this study, a process design method for the multi-pass shape drawing is proposed with consideration of the drawing stress. First, the shape drawing load was calculated to evaluate the shape drawing stress, and the intermediate die shape was determined by using an electric field analysis and the average reduction ratio. In order to evaluate whether material yielding occurs at the die exit, the drawing stress was determined by using the calculated shape drawing load. Finally, FE-analysis and shape drawing experiments were conducted to validate the design of the multi-pass shape drawing process. From the results of the FE-analysis and shape drawing experiments, it was possible to produce a sound shape drawn product with the designed process. The dimensional tolerances of the product were within the allowable tolerances.

Investigation of the Drawing Process of a Square Rod from a Round Bar by Using 3-D Finite Element Analysis

Wire and rod drawing is widely used in metal forming processes to obtain products such as rods and wires. Rods having shaped sections such as square, rectangle and irregular section are necessary to produce connecting pins and components of transformers. Important characteristics of the shaped drawing process are the corner filling and inhomogenious factor of strain that influence the dimensional accuracy and the good quality of the product. In this paper, a three-dimensional rigid-plastic finite element analysis is used to simulate the drawing process of a square rod from a round bar. A finite element method is also used to investigate the corner filling, forming load, stress distribution and inhomogenious factor of effective strain under various process parameter conditions, including the reduction of area, the die semi-angle, and the friction factor

VisualLISP을 이용한 다단이형인발 중간패스 단면형상설계 프로그램 개발

In the multi-pass shape drawing process, it is important to design the intermediate dies for producing sound products. Up to now, the design of the intermediate dies is mainly carried out by the industrial experts based on their experience. In this study, a design program was developed to design the intermediate dies for multi-pass shape drawing process. The program was programmed by using VisualLISP. In this program the intermediate dies can be designed by using the initial material shape and the final product shape. In order to verify the effectiveness, the program was applied to design the intermediate dies of multi-pass shape drawing for producing four teeth spline and gun slide. Finally, FE analysis and shape drawing experiment were performed to verify the effectiveness of the designed intermediate dies. As a result, it was possible to produce the drawn products with the required dimensional accuracy.

조향장치용 스플라인 샤프트 이형인발 공정변수 최적화

In the multi-pass shape drawing process, the appropriate process design is very important to produce sound products. The reduction ratio, die angle, and the intermediate die shape are very important process variable of the multi-pass shape drawing. The aim of this study is the determination of the reduction ratio, die angle, and the intermediate die shape of the 2 pass shape drawing process for producing steering spline shaft. In this study, FE analysis, Taguchi method, and ANN(artificial neural network) were applied to determine the appropriate reduction ratio, die angle, and intermediate die shape. After the determination of the process variables, FE analysis and drawing experiment were performed to evaluate the effectiveness of the determined process variables. The dimensional accuracy of the final drawn spline shaft was evaluated by using 3D surface profiler and 3D laser digitizing system.

크로스 롤러가이드의 다단형상인발공정 패스 스케쥴에 관한 연구

In the multi-pass shape drawing process, the pass schedule that includes the determination of reduction ratio and intermediate die shape is very important. This study used the equal reduction, equal load, and electric field analysis method for pass schedule of the multi-pass shape drawing. The reduction ratio was calculated by the equal reduction and equal load method. And the intermediate die shape was determined by the result of the electric field analysis and the calculated reduction ratio. The proposed pass schedule method was applied to a shape drawing for producing cross roller guide. Finally, FE-analysis and shape drawing experiment were performed to verify the effectiveness of the proposed method.

이형인발공정 하중예측에 관한 연구

The prediction of drawing load is very important in the drawing process. However, it is not easy to calculate the drawing load for the shape drawing process through a theoretical model because of a complex arbitrary final cross section shape. The purpose of this study is to predict drawing load in shape drawing process. The cross section of product is divided with small angle as much as similar with fan-shape. The drawing load of each section was calculated by theoretical model of round to round drawing process. And the shape drawing load was determined by summation of drawing load of each section. The effectiveness of the proposed method was verified through the FE analysis and shape drawing experiment. It had a good agreement between proposed method, FE analysis and experiment within about 3% errors.

다단 이형인발공정의 중간패스 단면형상 설계에 관한 연구

The multi-stage shape drawing is used to obtain long shaped products with high levels of dimensional accuracy and quality. It is important to design the cross sectional shapes of the intermediate passes to meet the required dimensional accuracy of the final product in the multi-stage shape drawing. Until now, the cross sectional shapes of the intermediate passes have been designed by the experiences. It is still remained unsolved problem to design the cross sectional shapes of intermediate pass drawing dies in the multi-pass shape drawing. In this study, a new technique is proposed to design the cross sectional shapes of intermediate passes. The proposed method is applied to a multi-stage shape drawing for a LM-guide which is one of the representative shape drawing products. In order to verify the effectiveness of the proposed method, FE-simulation and experiments have been carried out. The dimensional accuracy of the proposed method is compared with that of the conventional shape drawing process designed by the industrial engineers.

스플라인 이형인발을 위한 중간 다이 단면형상 설계

The cross sectional shape of intermediate die is one of important parameters to improve dimensional accuracy of final product in shaped drawing process. Until now, it has been designed by the experience or trial and error of the expert. In this study, the cross sectional shape of intermediate die for spline shape is determined by the electric fields analysis and scale factor method. The result of the electric fields analysis and scale factor method have been compared with that of the expert method. The effects of cross sectional shape on the dimensional accuracy were investigated by using FE-simulation. And then the multi-stage shaped drawing experiments were performed to verify the results of FE-simulation. As a result, the cross sectional shape from the electric fields analysis and scale factor method had the good dimensional accuracy. These two methods can be used for the method to obtain the cross sectional shape of intermediate die in shaped drawing process.

유한요소해석 및 다구찌법을 이용한 형상인발제품 치수정도 및 진직도 향상을 위한 다이스각 최적화

Recently, rods having irregular sections more complex than a rectangle or ellipse are necessary to produce mechanical parts. The cold shaped drawing process is used to obtain shaped drawn products with high levels of dimensional accuracy and quality. A cross roller guide, considered in this study, is one of the parts produced by shaped drawing process. A cross roller guide has a linear bearing system that rolls along a guide way. A cross roller guide is one of the most important components in terms of equipment because the quality of the product influences the precision linear motion. Therefore, the final dimensional accuracy of the linear rail in the shaped drawing is very important. The objective of this study is to find the optimized die angles to improve the dimensional accuracy and straightness of the final shaped drawn product. In order to achieve the aim of this study, design of experiment, FE-simulation, and the Taguchi method were used. Based on the analytical results, shaped drawing experiment has been performed to verify the result.

Optimal blank shape design using the initial velocity of boundary nodes

A new method of optimal blank shape design using the initial nodal velocity (INOV) has been proposed for the drawings of arbitrary shaped cups. With the given information of tool shape and the final product shape, corresponding initial blank shape has been found from the motion of boundary nodes. Although the sensitivity method, the past work of the present authors, has been proved to be an excellent method to find optimal blank shapes, the method has a problem that a couple of deformation analysis is required at each design step and it also exhibits an abnormal behaviors in the rigid body rotation prevailing region. In the present method INOV, only a single deformation analysis per each design stage is required. Drawings of L-shaped cup and oil pan have been chosen as the examples. At every case the optimal blank shapes have been obtained only after a few times of modification without predetermined deformation path. The deformed shape with predicted optimal blank almost coincides with the target shape at every case. Through the investigation the INOV is found to be very effective in the arbitrary shaped drawing process design.

초기 속도법을 이용한 최적 블랭크 설계 프로그램의 개발

A new method of optimal blank shape design using the initial nodal velocity (INOV) has been proposed for the drawings of arbitrary shaped cups. With the given information of tool shape and the final product shape, corresponding initial blank shape has been found from the motion of boundary nodes. Although the sensitivity method, the past work of the present authors, has been proved to be excellent method to find optimal blank shapes, the method has a problem that a couple of deformation analysis is required at each design step and it also exhibits an abnormal behaviors in the rigid body rotation prevailing region. In the present method INOV, only a single deformation analysis per each design stage is required. Drawings of practical products as well as oil-pan, have been chosen as the examples. At every case the optimal blank shapes have been obtained only after a few times of modification without predetermined deformation path. The deformed shape with predicted optimal blank almost coincides with the target shape at every case. Through the investigation the INOV is found to be very effective in the arbitrary shaped drawing process design.

A study on the corner filling in the drawing of a rectangular rod from a round bar

An important characteristic of the shaped drawing process, unlike the wire drawing process, is the corner filling which influences the dimensional accuracy of the product. In this study, therefore, in order to investigate the effect of process variables, such as the reduction in area, the semi-die angle, and the rectangular ratio to the corner filling, the drawings of a rectangular rod from a round bar have been simulated by using the three-dimensional rigid-plastic finite element method (FEM) and an artificial neural network has been introduced to reduce the number of simulations. To verify the results of the study, the experimental investigations were also carried out on real industrial products. According to the results, in the case of the irregular-shaped drawing process the main process variable on the corner filling is the combination of the semi-die angle but for the regular-shaped drawing process, the reduction in area has a significant effect on the corner filling.

Three-dimensional rigid–plastic finite element analysis of non-steady-state shaped drawing process

In this paper, non-steady-state shaped drawing processes have been investigated by using the three-dimensional rigid–plastic finite element (FE) method. In order to analyze the shaped drawing process, a method to define a straight converging die by considering a straight die part, a die radius part and a bearing part has been proposed. In addition, the modeling of the initial billet and the generation procedure of the mesh system have been suggested. The three-dimensional rigid–plastic FE simulation has been performed for a square sectional drawing process and its validity has been confirmed by comparison with existing experimental results. Under the same process conditions, the effect of perimeter ratio and drawing stress in the shaped drawing process has been investigated. Also, the effects of process variables, such as the reduction in area and semi-die angle, on drawing stress and corner filling in the drawing process of a square rod from a round bar have been investigated by using the rigid–plastic FE code developed. In order to investigate corner filling, the diagonal ratio is calculated and compared with the results of the FE simulations. Furthermore, limits of the process variables are determined by considering bulging and necking. From the results, an optimal process condition satisfying reasonable corner filling and a minimum value of drawing stress is suggested.