Punch Speed Research Articles

Study of Forging Forming of 7075 Aluminum Alloy Bicycle Pedal

Forging is simple and inexpensive in mass production. Metallic materials are processed through plastic deformation. This not only changes the appearance but also changes the internal organization of materials that improve mechanical properties. However, regarding manufacturing of plastic products, many processing factors must be controlled to obtain the required plastic strain and desired tolerance values. In this paper, we employed rigid-plastic finite element (FE) DEFORMTM software to investigate the plastic deformation behavior of an aluminum alloy (A7075) workpiece as it used to forge bicycle pedals. First we use Solid works 2010 3D graphics software to design the bicycle pedal of the mold and appearance, moreover import finite element (FE) DEFORMTM 3D software for analysis. The paper used rigid-plastic model analytical methods, and assuming mode to be rigid body. A series of simulation analyses in which the variables depend on different temperatures of the forging billet, round radius size of ram, punch speed, and mold temperature were revealed to confirm the predicted aluminum grain structure, effective stress, effective strain, and die radial load distribution for forging a bicycle pedal. The analysis results can provide references for forming bicycle pedal molds. Finally, this study identified the finite element results for high-strength design suitability of a 7075 aluminum alloy bicycle pedal.

Die design for a center pillar part by process analysis of hot stamping and its experimental verification

HSS (high-strength steel) is now commonly employed in various automobile structural reinforcements and crash protection systems. Although HSS has high strength, it has various disadvantages such as springback at room temperature and cracks; also, it is difficult to form HSS into complicated structures. The HPF process is a forming method that offers various advantages such as superior mechanical properties, good formability, and very small springback. However, relatively large-sized parts such as center pillars exhibit poor formability in the HPF process due to the limited material flow and thickness reduction in the process. Also, reduction in thickness leads to cracks. One of the reasons is the relatively high friction between the sheet and the die. In this study, in order to obtain the optimal conditions in the HPF process for center pillars, various process parameters were studied and analyzed by using the sheet forming software, J-STAMP. The effects of various parameters such as the heating temperature, blank holding force, punch speed, clearance (upper and lower dies), distance block, blank shape, and forming type were analyzed and compared.

Effects of processing parameters on microstructure and ultimate tensile strength of thixoformed AM60B magnesium alloy

The effects of processing parameters, such as the punch speed, reheating duration and reheating temperature, on microstructure and ultimate tensile strength (UTS) of thixoformed AM60B magnesium alloy have been investigated. The results indicate that low punch speed, short reheating duration or low reheating temperature often produces the defect of cold shuts or shrinkage porosities. On the contrary, gas pores can easily form. In addition, the reheating duration or temperature also has obvious effects on the primary particle size, fraction and morphology. The three parameters can significantly affect the UTS due to their effects on the formation of pores (cold shuts, shrinkage porosities and gas pores). But they can not alter the fracture path during tensile testing and the path is always along the secondarily solidified structures between the primary particles. The effect of pore amount on the UTS is lager than that of the primary particle size, fraction or morphology. In view of their effects on the microstructure compactness and the resultant UTS, the optimized parameters are reheating for 130 minutes at 610 °C and punch speed of 3 m/s.

Finite-Element Simulation and Experimental Investigation of Isothermal Backward Extrusion of 7075 Al Alloy

This paper reports on an experimental and finite-element analysis of a backward extrusion process of 7075 Al alloy. The influence of punch speed and billet temperatures on the backward extrusion process was investigated. DEFORM-3D software was used for finite-element simulations. A backward extrusion die was designed and manufactured for the purpose of experimental research. From simulation, the forming load and stress/strain distribution of the billet were obtained. The simulation results show that the effective stress/strain distributions are inhomogeneous in the deformed billet. Finite-element method has been used successfully to predict the backward extrusion load, indicating the good accuracy of the simulation results. In this study, the effects of the different temperatures and punch speeds on the effective stress/strain distribution and forming load during forming process were investigated.

프론트필러의 핫스템핑 공정설계를 위한 블랭크형상의 최적화 연구

Hot stamping is a forming method that offers various advantages such as superior mechanical properties, good formability, and very small springback. However, relatively large-sized parts, such as front pillars, exhibit poor formability when hot stamped due to the limited material flow and thickness reduction imparted by the process. This reduction in thickness can also lead to cracks. One of the reasons is the relatively high friction between the sheet and the die. In this study, in order to obtain the optimal conditions for hot stamping of front pillars, various process parameters were studied and analyzed using the sheet forming software, J-STAMP. The effects of various parameters such as the die structure, blank shape, blank holding force, punch speed, clearance(upper and lower dies) and distance block were analyzed and compared.

Effect of initial texture on deformation behavior of AZ31 magnesium alloy sheets under biaxial loading

Deformation behavior of an AZ31 Mg alloy under a biaxial loading has been studied in relation to the initial texture developed during a prior hot-rolling process. Sheet specimens were thus prepared from a hot-rolled plate in the RD–TD planes (RTD) and ND–TD planes (NTD) to examine the effects of initial texture. Biaxial dome forming tests were then carried out under the punch speed of 0.1mm/s at room temperature (RT), 100°C, and 200°C to obtain punch load vs. displacement curves during dome-forming tests. Different twin modes were observed under a biaxial loading at RT, viz. {1 0 1¯ 1} compression twins and {1 0 1¯ 1}–{1 0 1¯ 2} double twins in RTD specimens, while {1 0 1¯ 1} compression twins generated through the rotation of {1 0 1¯ 2} extension twins developed earlier in NTD specimens. Formability of NTD sheets was observed to increase more rapidly compared to that of RTD specimens as forming temperature was raised, which might be accounted for by reduced critical resolve shear stresses (CRSS) of prismatic slips due to their higher Schmid factor values.

Fabrication of aluminum 1050 micro-channel proton exchange membrane fuel cell bipolar plate using rubber-pad-forming process

The rubber-pad-forming process is used to fabricate a metallic bipolar plate made of aluminum 1050 for use in a proton exchange membrane fuel cell. To determine the shape of the bipolar plate channel, the effects of the rib and channel cross-sections on the velocity field are investigated using the STAR-CCM + commercial computational fluid dynamics software. Air enters the cell through the bipolar plate and spreads throughout the cell, and a large quantity of air then uniformly permeates the membrane’s surface. The rate distribution of most of the chemical reactions occurring in the channels is determined in the final model. The designed bipolar plate is fabricated using a hydraulic press with a capacity of 200 t. The effects of various parameters such as the type of plate, plate thickness, punch speed, press pressure, rubber pad thickness, and rubber pad hardness are studied. Furthermore, the formability of the bipolar plate is evaluated in detail.

Experimental Assessment of High Temperature Formability of Boron Steel Sheet Manufactured With a Spring Compound Bending Die

Bending behavior occurs in the hot press forming process, resulting in many cases of failure during forming. To address the problem of cracking and improve the formability and mechanical properties of boron steel sheets in the bending process, an experiment has been carried out by using a spring compound bending die. Also, a comparison has been made between the traditional U-bending die and the spring compound bending die with regard to formability. The influence of the parameters for hot press forming such as the heating temperature, punch speed, and die radii on the mechanical properties and microstructure was analyzed by tension testing and metallographic observations.

Evaluation of the formability of a bipolar plate manufactured from aluminum alloy Al 1050 using the rubber pad forming process

The rubber pad forming process has been used to fabricate metallic bipolar plates from aluminum 1050 alloy for use in a proton-exchange membrane fuel cell. The plates were fabricated using a 200 ton hydraulic press and the effects of the process parameters of the rubber pad forming process (plate thickness, punch speed, press pressure, rubber thickness and rubber hardness) on the forming depth and thinning were evaluated.

Effect of Blank Holder Force with Low Frequency Vibration Technique in Circular-Cup Deep-Drawing Using AZ31 Magnesium Alloy Sheet

In the deep-drawing process, the application of low-frequency vibration to the blank material has recently been focused on with the aim of improving the friction performance between the die and the blank material. A servo-controlled press machine is suitable for applying low-frequency vibration to the blank during the deep-drawing process, because the punch speed and blank holder force (BHF) are easily controlled as process parameters by using the servo motors. In this study, a BHF with low-frequency vibration was proposed as a technique for improving deep-drawability, which is mainly affected by the friction performance and the lubricant condition. We found that the friction performance between the blank surface and the blank holder was decreased in the case of a BHF with low-frequency vibration since the lubricating oil rapidly flowed into the clearance during the forming process. Furthermore, for a BHF with low-frequency vibration, the punch force and the deformation resistance were lower than those in a deep-drawing test without low-frequency vibration.

The Springback Characteristics of a Porous Tantalum Sheet-Metal

This study examines the elastic recovery (springback) of a porous tantalum foam after sheet forming operations. The foam and sheet-like form is applicable to bone ingrowth surfaces on orthopedic implants and is desirable due to its combination of high strength, low relative density, and excellent osteoconductive properties. Forming of the foam improves nestability during manufacture and is essential to have the material achieve the desired shape. Experimentally, bending about a single axis using a wiping die is studied by observing cracking and measuring springback. Die radius and clearance strongly affect the springback properties, while punch speed, embossing, die radius, and clearance all influence cracking. To study the effect of the foam microstructure, bending also is examined numerically. A horizontal hexagonal mesh comprised of beam elements is employed, which allows for the densification that occurs during forming. The flow strength of individual tantalum struts is directly measured in an atomic force microscope. The numerical results show that as the hexagonal cells are elongated along the sheet length, elastic springback decreases. By changing the material properties of the struts, the models can be modified for use with other open-cell metallic foams.

Effect of Blank Holder Force with Low Frequency Vibration Technique in Circular-Cup Deep-Drawing Using AZ31 Magnesium Alloy Sheet

In the deep-drawing process, the application of low-frequency vibration to the blank material has recently been focused on with the aim of improving the friction performance between the die and the blank material. A servo-controlled press machine is suitable for applying low-frequency vibration to the blank during the deep-drawing process, because the punch speed and blank holder force (BHF) are easily controlled as process parameters by using the servo motors. In this study, a BHF with low-frequency vibration was proposed as a technique for improving deep-drawability, which is mainly affected by the friction performance and the lubricant condition. We found that the friction performance between the blank surface and the blank holder was decreased in the case of a BHF with low-frequency vibration since the lubricating oil rapidly flowed into the clearance during the forming process. Furthermore, for a BHF with low-frequency vibration, the punch force and the deformation resistance were lower than those in a deep-drawing test without low-frequency vibration.

Simulation Study on Influence of Forming Process Parameters on Backward Extrusion Height of 6061 Aluminum-Alloy Wheel

Backward extrusion process of aluminum-alloy wheel forging is analyzed by the finite element method. The influence of punch speed and forming temperature on the backward extrusion height of 6061 aluminum alloy wheel is discussed. Studies show that the backward extrusion height increases with increasing forming temperature, and with decreasing punch speed at the same deformation load. It is indicated that when the ranges of forming temperature is from 450 to 500°C and the punch speed is 0.5-1 mm/s, the aluminum alloy wheel has the optimal forming quality. The analysis and conclusions in this paper are helpful in developing the hot extrusion technology specification of 6061 aluminum alloy.

Effect of manufacturing processes on contact resistance characteristics of metallic bipolar plates in PEM fuel cells

In this study, metallic bipolar plate (BPP) samples manufactured with stamping and hydroforming under different process conditions were tested for their electrical contact resistance characteristics to reveal the effect of manufacturing type and conditions. Punch speed and force in stamping, and pressure and pressure rate in hydroforming were selected as variable process parameters. In addition, two different channel sizes were tested to expose the effect of BPP micro-channel geometry and its consequences on the contact resistance. As a general conclusion, stamped BPPs showed higher contact conductivity than the hydroformed BPPs. Moreover, pressure in hydroforming and geometry had significant effects on the contact resistance behavior of BPPs. Short term corrosion exposure was found to decrease the contact resistance of bipolar plates. Results also indicated that contact resistance values of uncoated stainless steel BPPs are significantly higher than the respective target set by U.S. Department of Energy. Conforming to literature, proper coating or surface treatments are necessary to satisfy the requirements.

Numerical Simulation of the Auto Claw-Pole Thixoforming Process

Thixoforming is an effective near-net-shape forming process to produce components with complex geometry and in fewer forming steps. In this study, thixoforming was used to replace the conventional hot forging to form the auto claw-pole. The finite element code Forge2008Ó was used to simulate the auto claw-pole thixoforming process. The results show that initial billet temperature, punch speed, die temperature and friction have strong impact on the forming process. Finally, the reasonable process parameters for the auto claw-pole thixoforming were obtained: initial billet temperature 1430~1440°C, punch speed 100~200mm/s and die temperature 300~400°C.

Impact of Process Parameters on the Auto Claw-Pole Thixoforming Process

Thixoforming of steel is a potential forming technology, which can realize near-net-shape forming process with good quality in one forming step. In this paper, thixoforming process was used to replace the conventional hot forging process to form the auto claw-pole. The finite element code Forge2008Ó was used to simulate the auto claw-pole thixoforming process. The impact of three main process parameters such as initial billet temperature, punch speed and die temperature on the forming process were investigated. The reasonable process parameters for the auto claw-pole thixoforming were obtained: initial billet temperature 1430~1440°C, punch speed 100~200mm/s and die temperature 300~400°C.

Theoretical estimation of punch velocities and displacements of single-punch and rotary tablet machines.

The speed of travel of punches during compaction by a Manesty F3 single punch and D3B Rotary punch tablet machine has been derived from machine dimensions, normal operating speeds and by consideration of the consolidation of a theoretical compact. The analysis may also be used for machines with other dimensions, operating at different speeds with other materials, but would require modification if the punch head design on the rotary machine differed significantly. Punch speeds at the beginning of the compression cycle were similar for the two types of machines, namely 10.36 and 10.24 cm s-1 for the single and rotary machines. The time to reach maximum compression and the total time of contact between punches and powder for the single punch machine was 0.1 s for a compaction force of approximately 40 KN. For the rotary machine operating at approximately the same force, these two parameters were found to be 0.052 and 0.083 s respectively. The additional contact time is associated with a period during which there is no vertical movement of the punch, providing a 'dwell' time of 0.0314 s when the powder is held at a constant volume.

AZ31B 마그네슘 합금판재의 성형특성 평가를 위한 실험적·해석적 연구

Abstract This study aimed at providing an experimental database for the mechanical properties of AZ31B magnesium alloy sheet such as stress-strain curve, yield stress, R-value and forming limit diagram(FLD) at various strain-rates and temperatures. Tensile tests were carried out on specimens having the orientations of 0°, 45° and 90° to the rolling direction with different crosshead speeds in the range between 0.008 and 8 mm/s at temperature from 25(room temperature) to 300℃. The influence of the specimen gage length on the tensile properties was investigated. FLD tests were performed at punch speed of 0.1 and 1.0 mm/s in the same temperature range as that of the tensile tests. Swift cup tests were conducted to verify the usefulness of the material database and the reliability of the finite element analysis(FEA). The effects of strain-rate as well as temperature were taken into account in these simulations. It was shown that the FLD-based failure was reasonably well predicted by the thermal-deformation coupled analysis for this rate-sensitive material.

Blank Optimization in Elliptical-Shape Sheet Metal Forming Using Response Surface Model Coupled with Reduced Basis Technique and Finite Element Analysis

The present study aims to determine the optimum blank shape design for the deep drawing of Elliptical-shape cups with a uniform trimming allowance at the flange i.e. cups without ears. This earing defect is caused by planar anisotropy in the sheet and the friction between the blank and punch/die. In this research, a new method for optimum blank shape design using finite element analysis has been proposed. Present study describes the approach of applying Response Surface Methodology (RSM) with Reduced Basis Technique (RBT) to assist engineers in the blank optimization in sheet metal forming. The primary objective of the method is to reduce the enormous number of design variables required to define the blank shape. RBT is a weighted combination of several basis shapes. The aim of the method is to find the best combination using the weights for each blank shape as the design variables. A multi-level design process is developed to find suitable basis shapes or trial shapes at each level that can be used in the reduced basis technique. Each level is treated as a separated optimization problem until the required objective – minimum earing function – is achieved. The experimental design of RSM method is used to build the approximation model and to perform optimization. MATLAB software has been used for building RSM model. Explicit non-linear finite element (FE) Code Abaqus/CAE is used to simulate the deep drawing process. FE models are constructed incorporating the exact physical conditions of the process such as tooling design like die profile radius, punch corner radius, etc., material used, coefficient of friction, punch speed and blank holder force. The material used for the analysis is Stainless steel St12. A quantitative earing function is defined to measure the amount of earing and to compare the deformed shape and target shape set for each stage of the analysis. The cycle is repeated until the converged results are achieved. This iterative design process leads to optimal blank shape. So through the investigation the proposed method of optimal blank design is found to be very effective in the deep drawing process and can be further applied to other stamping applications.

Investigation of Influence Parameters on Forming Limit Diagrams of Aluminum Alloy-AA2024

Sheet metal forming technology is the keyword for many industries such as aerospace, aeronautics and automobile industries. Customer expectations, quality and safety requirements and market competitions require sheet metal forming operations to be well analyzed before the process to fulfill all these requirements. In this study, combination of FEA (finite element analysis) and mechanical material characterization were used in order to improve sheet metal forming operations while considering cost and quality. On the material characterization side of the studies, simple uniaxial tensile tests were conducted to obtain anisotropy parameters and yield points along different directions and hydraulic bulge test (HBT) was performed to obtain plastic behavior of the material up to 0.7 strains. Deformation measurements were conducted using optical measurement system GOM-ARAMIS while a 60-ton hydraulic press; Zwick/Roell BUP600 was used to deform the sheet part AA2024-0 aluminum alloy. Effects of process parameters, which are initial material thickness, lubrication and punch speed, on sheet metal formability and forming limit diagrams (FLDs) were investigated. On the study of thickness effects, sheet metals those having 0.81mm, 1.27mm and 1.60mm thickness were tested. Punch velocities of 250mm/min, 500mm/min and 750mm/min were used to investigate effect of punch speed on formability of sheet metals. Finally, PTFE (Polytetrafluoroethylene), paraffin lubricated and dry conditions were presented to obtain friction effects. FE analyses were performed to simulate experiments and to obtain friction coefficients of different lubricants. Good correlations were observed between numerical simulations and experimental results.