Forging Force Research Articles

Preform geometry determination for a connecting rod forging by CEL model in Abaqus™

AbstractForging is a widely used manufacturing process, and its design and modeling are important to reducing production costs, increasing die lifespan, and improving the mechanical properties of the final product. In this study, the forging process of a connecting rod was modeled using 3D coupled Eulerian Lagrangian (CEL) analysis by FEM. The methodology adopted achieved to determine a preform geometry that reduces final flash and forging load, while ensuring complete filling of the stamp. Starting from the final geometry, the final die was designed. After the first result for an approximately 27% of flash, the material distribution was adjusted decreasing it at the regions where the flash was too large. After an iterative method was applied to determine better preform, a proposal was found that reduced forging force by approximately 42% and the percentage of flash volume by 64% in comparison with the first one. A final flash of about 10% is considered a good objective to reach. Lower values may cause many iterations, not a significant difference in forging loads, the risk of an unfilled die, and complex preform geometries.

The Cold Forming Analysis of Eccentric Parts

In this study, a multi-stage cold forming process for the manufacture of eccentric parts is studied numerically with low carbon steel AISI 1022. The forming processes through five stages and four stages include two-step forward extrusion, eccentric upsetting, and backward extrusion over a moving punch. The numerical simulations of cold forming are conducted using the code of DEFORM-3D. The formability of the workpiece is studied numerically, such as the effect on forging load responses, maximum forging loads, effective stress and effective strain distributions and metal flow pattern. The maximum effective stress of 819 MPa at the third stage is the largest among the stages. The maximum effective stresses of the last stages for the four-stage forming and five-stage forming are almost the same. The effective strain distributions of the last stages for the four-stage forming and five-stage forming are very similar. The flow line distributions of the last stages both for the four-stage forming and five-stage forming are also very similar. For the maximum axial forging force and forming energy, the third stage of eccentric upsetting at the upper end is the largest among the stages. The total maximum axial forging loads from the first to the last stages are 795.8kN for the five-stage forming and 590.4kN for the four-stage forming; and the total forming energies are about 0.751kJ for the five-stage forming and 0.671kJ for the four-stage forming. Although the total maximum axial forging loads and total forming energy of the four-stage forming are smaller than those of the five-stage forming, the maximum lateral forging force in the last stage of the four-stage forming is almost five times that of the last stage of the five-stage forming. Increasing lateral forging force may lead to wear and damage of the punch. Moreover, the inner surfaces of the hexagonal cavity at the upper end are relatively uneven because of simultaneous eccentric upsetting and backward extrusion in the last stage of the four-stage forming.

Application of FEM and Abductive Network to Determine Forging Force and Billet Dimensions of Near Net-Shape Helical Bevel Gear Forging

In this paper, the use of the finite element method in conjunction with abductive network is presented to predict the maximum forging force and the volume of billet during near net-shape helical bevel gear forging. The maximum forging load and volume of billet are influenced by the process parameters such as modules, number of teeth, and die temperature. A finite element method is used to investigate the forging of helical bevel gear. In order to verify the prediction of FEM simulation for forging load, the experimental data are compared with the results of current simulation. A finite element analysis is also utilized to investigate the process parameters on forging load and volume of billet. Additionally, the abductive network was applied to synthesize the data sets obtained from the numerical simulation. The prediction models are then established for the maximum forging load and volume of billet of near net-shape helical bevel gear forging under a suitable range of process parameters. After the predictions of the maximum forging force and the volume of billet, the optimum of the power of forging machine and the dimensions of billet are determined.

Bending vibrational tool for friction stir welding process

Beside beneficial aspects of friction stir welding such as solid-state joining process, no melting, no recasting, etc., there are some disadvantages like considerable axial forging force especially for high-strength materials. Researchers have developed several innovative ideas to diminish the process problems. In the present study, to investigate the effect of bending vibrations, an ultrasonic vibratory tool of friction stir welding, in bending mode, has been designed and manufactured. Firstly, the vibratory tool was designed for the operating resonance frequency of 20 KHz in ABAQUS software. This tool consists of transducer, horn, and welding tool. Using the optimal dimensions achieved from the modal analysis, the FSW tool has been manufactured. Then, experimental investigations verify the validity of the tool design process, such as clamping flange position, resonance frequency, and so on. The friction stir welding of aluminum Al6061 and Teflon plates has been done with lathe machine. FSW-assisted ultrasonic vibrations in bending mode show some advantages in comparing with linear mode, such as decreased tool length and increased efficiency of vibrational energy transferring to the tool tip. Finally, with respect to the indicated improvements, reduction and rise of welding forces and temperature have been observed, respectively.

Application of Taguchi Method in the Optimization of Friction Stir Welding Parameters of an Aeronautic Aluminium Alloy

The Friction Stir Welding (FSW) process is still an innovative solid state mechanical processing technology enabling high quality joints in materials previously considered with low weldability such as most of the aeronautic aluminium alloys. The Taguchi method was used to find the optimal FSW parameters for improvement mechanical behaviour of AA2024-T351. The Taguchi design is an efficient and effective experimental method in which a response variable can be optimized. The parameters considered were vertical downward forging force, travel speed and pin length. An orthogonal array of L9 (34) was used; ANOVA analyses were carried out to identify the significant factors affecting tensile strength (GETS), bending toughness (GEB) and hardness field. An algebraic model for predicting the best mechanical performance was developed and the optimal FSW combination was determined using this model. The results obtained were validated by conducting confirmation experiments. Significant interest has been shown in the use of advanced welding techniques for aircraft structures, particularly given the design and manufacturing benefits they afford over established mechanical joining methods. Whilst a variety of welding methods have been identified for airframe structures, friction stir welding is an important candidate technique that is distinctive in being a low energy, solid-state process [1]. Although the friction stir welding joints have a better quality compared to the fusion techniques, there are still some defects that may arise and which are very sensitive to small variations in process parameters. Typical defects that may arise in FSW joints result from: imperfect stir of the materials during the processing, inadequate surface preparation, lack of penetration of the pin and non-uniform vertical forging forces along the material thickness. Some characteristic FSW defects are lack of penetration (typically addressed as kissing-bond), root flaw (concerning weak or intermittent linking), voids on the advancing side and second phased particles and oxides alignment under the shoulder [2]. Advanced aerospace aluminium alloys have been required to allow high fracture toughness, higher fatigue performance, high formability, and superplasticity to meet the needs for lower structural weight, higher damage tolerance and durability [3].

Numerical and experimental study on the effect of die shape and billet size in the forging process of axi-symmetric parts

Precision forging is defined as a flashless near-net-shape forging process which produces parts with high surface quality and with dimensional accuracy. This technique has become a key method in the field of manufacturing to improve productivity and to challenge in these competitive market conditions. This paper presents the effect of die shape and initial billet size on the parameters of axi-symmetrical precision forging including forging force, stress-strain distribution, material flow pattern, and contact pressure between the die and the billet. The less forging force, the cheaper the equipment needed. More homogeneous strain distribution leads to higher reliability of products as well as smoother mechanical properties. Material flow pattern is a shortcut to predicting final grain order and die wear pattern. Contact pressure directly affects the die wear and life. By controlling these parameters, some factors like die life, mechanical properties of product, and equipment costs could be optimised. Results prove that the appropriate billet diameter (Db/Dd) can be effective factor on the forging force, lower required materials and material flow. A comparison has been done between numerical and experimental results. A good agreement was achieved between theory and practice.

Analytical Model Study of Ellipse Crank Arm Final Upset Forging Force on Slab Method

According to the structure of the crank arm, the conformal mapping method was adopted to transform the elliptical section map of it to the round. Then by the slab method an analytical model for final upsetting force of the crank arm was established, which is a derivation based on assumptions of axisymmetric plastic forming status. Finally, a simulation was implemented in case of the second crank of crankshaft 6G32. Accordance to it the accuracy of the analytical model was examined. Further more the causes of the data deviation from the model and the simulation were analyzed in this thesis.

Influence of process parameters on impact toughness and hardness of dissimilar AISI 4140 and AISI 304 continuous drive friction welds

Dissimilar joints between austenitic stainless steel and low alloy steel are extensively used in many high temperature applications in the energy conversion systems. In the present investigation, emphasis is made on the influence of process parameters on the impact toughness and hardness of the friction welded joints between these two materials. The important process parameters in friction welding such as friction force, forge force, and burn-off lengths are considered for optimization by Taguchi method using L8 27 orthogonal array. It is found that under low friction force, forging force, and burn-off conditions, the impact toughness is high due to the observed acicular martensite. Low impact toughness is reported for the welds made at higher levels of the parameters. Carbon depletion is also observed close to interface in low alloy steel side. Microhardness at the weld center is less than the microhardness on either side at the interface of low alloy steel and austenitic stainless steel close to weld center. The contribution of each parameter and significance of interactions of these parameters is determined by Taguchi method. Among these parameters, friction force has significant influence and forging force has negligible influence on microhardness. The burn-off has maximum influence while forge force has minimum effect on toughness of the welds. Statistical analysis of variance is carried out, optimum process parameters are evaluated, and regression equations are obtained.

Effect of equivalent feed amount per revolution on cold rotary forging process by 3D elastic–plastic dynamic explicit FE method

Cold rotary forging is an advanced and very complex incremental metal forming process with multifactor coupling interactive effects. Previous research is mainly based on experimental and analytical methods and thus cannot provide full details on the deformation characteristics and mechanisms of cold rotary forging. In the current work, a decisive factor in cold rotary forging, namely equivalent feed amount per revolution , is first determined, and its mathematical expression is presented. A reasonable three-dimensional elastic–plastic dynamic explicit finite element model of cold rotary forging of a cylindrical workpiece was established under the ABAQUS software environment. Through numerous simulation calculations and the analysis of equivalent plastic strain, it has been found that there are three plastic penetrating states of the cylindrical workpiece under different . On the basis of these plastic penetrating states, the effect laws of on the metal flow, degree of inhomogeneous deformation of workpiece and force and power parameters have been investigated, and thus, the deformation characteristics and mechanisms of cold rotary forging have been thoroughly revealed. The results show that with increasing , the ‘mushroom’ effect of the deformed cylindrical workpiece becomes less obvious and the deformation becomes more homogeneous, while the maximum axial forging force and forging moment gradually increase. Second, the effect of by changing the inclination angle γ of the upper die on the cold rotary forging process is different from that by changing the feed rate v of the lower die or the rotational speed n of the upper die.

Effect of Position between Upper Die and Workpiece on Cold Rotary Forging

Cold rotary forging is an advanced but very complex incremental metal forming technology with multi-factors coupling interactive effects. The position between the upper die and the workpiece has a significant effect on the cold rotary forging process. 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 experimentally. On the basis of this reliable 3D FE model, the effects of the position between the upper die and the workpiece on the cold rotary forging process have been thoroughly revealed. The results show that with increasing the distance between the pivot point of the upper die and the centre of the workpiece, the deformation of the workpiece becomes more inhomogeneous and the maximum axial forging force and forging moment gradually increase. The results of this research not only provide valuable guidelines for the installation and adjustment of dies in the cold rotary forging process, but also help to better understand the deformation mechanisms of cold rotary forging.

Effect of size of the cylindrical workpiece on the cold rotary-forging process

Cold rotary forging is an advanced but much complex incremental metal forming process with multi-factors coupling interactive effects. The size of the workpiece has a significant effect on the cold rotary-forging process. In the current work, a reliable 3D elastic–plastic dynamic explicit FE model of cold rotary forging of a cylindrical workpiece is established under the ABAQUS software environment. Based on the valid 3D FE model, the effect laws of size of the cylindrical workpiece on metal flow, degree of inhomogeneous deformation of workpiece and force and power parameters in the cold rotary-forging process have been investigated. The research results show the following: (1) With increasing the initial diameter of the cylindrical workpiece D 0, the “mushroom” effect of the deformed cylindrical workpiece becomes less obvious and the deformation becomes more homogeneous, while the maximum axial forging force and forging moment gradually increase. (2) With increasing the initial height of the cylindrical workpiece H 0, the “mushroom” effect of the deformed cylindrical workpiece becomes more obvious and the deformation becomes more inhomogeneous. Meanwhile, the maximum axial forging force and forging moment increase slowly. (3) The effect of the height to diameter ratio H 0 /D 0 by changing D 0 on the cold rotary-forging process is different from that by changing H 0. The above results have been explained by the critical parameter affecting the cold rotary-forging process significantly, namely the length to height ratio of the plastic deformation zone K ¯ .

Application of Abductive Network and FEM to Predict the Maximum Forging Force and the Final Face Width of Spur Gear

The process of precision gear forging has been developed recently because of its advantages of giving high production rates and improved strength. For complete filling up, predicting the power requirement and final face width is an important feature of the forging process. A finite element analysis is utilized to investigate the maximum forging force and final face width under different process parameters such as modules, number of teeth, and the ratio of the height to diameter of billet. The abductive network is then applied to synthesize the data sets obtained from the numerical simulation, and a prediction model is established ultimately. Employing the predictive model can provide valuable references in prediction of the forging force and final face width under a suitable range of process parameters.

Critical forming force in rotary forging and the application of tungsten carbide dies

In precision cold forming in a rotary forging press the final stage of deformation occurs at a diminishing die closure rate to give the required accuracy of form. Earlier studies have indicated that elastic distortion of the dies can result in significantly increased die contact area and forming force as compared with an ideal rigid die system. In this paper the analysis is developed to give an expression for a critical forging force below which forming will not proceed. The critical force is dependent on the elastic modulus of the dies and it is shown that by using tungsten carbide dies, with a modulus almost three times that of tool steels, the forging force can be reduced significantly. A force reduction of about 50% is achieved in upsetting experiments on strain hardened steel billets by the use of tungsten carbide instead of tool steel.

The influence of elastic die distortion on forming force in rotary forging

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.