Effect Of Punch Speed Research Articles

THE INFLUENCE OF THE NON-SYMMETRIC PUNCHING PROCESS PARAMETER ON THE HOLE SHAPE AND QUALITY OF A COMMERCIALLY PURE TITANIUM SHEET

Recently, punching technology has become one of the promising manufacturing techniques for a thin metallic sheet. The processing parameters used in this technique have been recognized to influence the hole shape produced in the working materials. Therefore, it is important to understand the effect of the punching process parameters on the hole shape and quality over the manufactured materials. This study aims to determine the influence of the punching process on the non-symmetrical hole shape and quality over a commercially pure titanium sheet. The effect of punch speed on the punch force and the sheared surface is also studied, by applying the punch velocities of 10, 35 and 70 mm/s. The sheared surface of the hole was examined at its four different sides, namely K (straight), L (outer radius), N (inner radius) and M (straight). The results show uneven distribution of punch strength as detected at the affected region of the non-symmetrical hole. In addition, the punch force increased with the increase of punch speed. Meanwhile, the sheared surfaces on each side were apparently different. The burnish height on the side of the radius was found to be about 0.038 mm higher than that on the straight side. The burnish height on the radius side increases by 0.43 mm with the increasing punch speed from 10 to 70 mm/s. However, the increased punch velocity did not always increase the burr height. The work hardening that occurs on the straight side is smaller by about 15% than the radius side.

The effect of punch speed on frictional contact mechanics of finite-thickness graded layer resting on the rigid foundation

The present article investigates frictional contact mechanics between a moving punch possessing sharp ends and a finite-thickness functionally graded layer resting on the rigid foundation. The rigid punch has either flat or semi-circular profiles, and it moves over the functionally graded layer at a steady subsonic speed. The tangential load developed by the moving punch is proportional to the normal applied load since Coulomb’s friction law is adopted. Variations of shear modulus and mass density through the thickness of the layer are expressed by exponential functions, whereas the variation of the Poisson’s ratio is neglected. Governing partial differential equations are derived considering two-dimensional theory of elastodynamics, and these equations are solved analytically utilizing Galilean and Fourier transformations. Equations are reduced to a singular integral equation of the second kind. Singular integral equation is solved, and results of analytical approach are compared with those obtained by means of the finite element method in elastostatic case. A very good agreement is achieved between analytical and computational results. Parametric analyses are performed to observe the influences of punch speed, material inhomogeneity and coefficient of friction upon contact stresses of a finite-thickness graded layer resting on the rigid foundation. Stresses observed for relatively thin softening layers are much sensitive to the variation in punch speed.

二層円管の成形性におけるパンチ速度の影響

二層円管の成形性におけるパンチ速度の影響

Forming of Al 5182-O in a Servo Press at Room and Elevated Temperatures

Aluminum alloys are increasingly used in automotive manufacturing to save weight. The drawability of Al 5182-O has been proven at room temperature (RT) and it is also shown that formability is further enhanced at elevated temperatures (ETs) in the range of 250–350 °C. A cost effective application of ET forming of Al alloys can be achieved using heated blank and cold dies (HB–CD). In this study, the material behavior of Al 5182-O is characterized using tensile test and viscous bulge test at RT. The nonisothermal finite element model (FEM) of deep drawing is developed using the commercial software pamstamp. Initially, deep drawing simulations and tests were carried out at RT using a 300 ton servo press, with a hydraulic cushion. The predictions with flow stress curves obtained from tensile and bulge tests were compared with experimental data. The effect of punch speed and temperature rise during forming at RT is investigated. The warm forming simulations were carried out by combining material data at ETs obtained from the literature. The coupled effects of sheet temperatures and punch speeds are investigated through the finite element analysis (FEA) to provide guidelines for ET stamping of Al 5182-O.

Experimental studies of deep drawing of AZ31B magnesium alloy sheet under various thermal conditions

The effect of temperature and temperature gradient within the blank on formability of AZ31B-O magnesium alloy is investigated. The effect of blank size on the success of isothermal deep drawing is studied. As blank size increases, forming under isothermal conditions becomes more difficult. To address this issue, non-isothermal forming is investigated and a formability window is identified in which the temperature at the punch nose must lie below the flange temperature to promote enhanced drawability, but above the temperature for activation of non-basal slip systems (to avoid low temperature fracture). The effect of punch speed on the forming forces, thickness and strain distribution within the formed cup is also investigated. At higher punch speeds, small cracks initiate at the punch radius region which increases the possibility of failure. Finally, the fracture surfaces from each thermal condition are observed using scanning electron microscopy. It is demonstrated that the fracture mechanism during deep drawing of magnesium alloy AZ31B is dependent on the forming temperature which controls the active deformation mechanisms.

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.

Investigation of forming process for micro‐socket connecters

The development of micro‐electro‐mechanical systems (MEMS) and micro system technology (MST) has improved the development of micro manufacture technologies such as microforming. In this investigation, the micro‐socket connecter was selected as the forming target since it is widely used in micro electronic industries. The forming scheme of micro‐socket connecters was investigated from the viewpoint of three procedures: blanking the contour and locating hole, blanking the socket and the bending process. The forming experiments were performed with T2 copper foil of 0·08 mm thickness. The effects of punch speed and grain size on the maximum punch force, bending force, cross‐sectional quality and springback angle were studied in detail. The results show that the maximum punch force decreases with the increase in punch speed and grain size. However, the maximum punch force increases slightly with the increase in grain size in the blanking socket procedure. The smoothly sheared area ratio becomes smaller with the increase in punch speed and grain size. The punch speed has a negative effect and grain size has a positive effect on springback angle. Analysis was carried out by considering the polycrystalline structure of the metallic material.

Corrosion resistance characteristics of stamped and hydroformed proton exchange membrane fuel cell metallic bipolar plates

Metallic bipolar plates have several advantages over bipolar plates made from graphite and composites due to their high conductivity, low material and production costs. Moreover, thin bipolar plates are possible with metallic alloys, and hence low fuel cell stack volume and mass are. Among existing fabrication methods for metallic bipolar plates, stamping and hydroforming are seen as prominent approaches for mass production scales. In this study, the effects of important process parameters of these manufacturing processes on the corrosion resistance of metallic bipolar plates made of SS304 were investigated. Specifically, the effects of punch speed, pressure rate, stamping force and hydroforming pressure were studied as they were considered to inevitably affect the bipolar plate micro-channel dimensions, surface topography, and hence the corrosion resistance. Corrosion resistance under real fuel cell conditions was examined using both potentiodynamic and potentiostatic experiments. The majority of the results exhibited a reduction in the corrosion resistance for both stamped and hydroformed plates when compared with non-deformed blank plates of SS304. In addition, it was observed that there exist an optimal process window for punch speed in stamping and the pressure rate in hydroforming to achieve improved corrosion resistance at a faster production rate.

English

The hydroforming deep drawing process is one of the sheet metal forming process. The pressurized fluid is used as a medium in this process. Hydro forming technology provides an attractive alternative to conventional matched die forming, especially for cost sensitive, lower volume production and for parts with irregular contours. The performance of deep drawing process can be enhanced by using the liquids. The process performance can be improved through improvement of parameters like draw ratio, thickness ratio, ratio of volume to surface area of product, no scratches developed on outer side of cup and formability index. In this process, the pressurized liquid is utilized for many purposes as the sheet metal blank is supported in entire forming process, elimination of fracture in deformation of cup and formation of wrinkles on the wall and edges of the cup are minimized. The liquid pressure effects on radial, hoop and drawing stresses of blanks in during the process. The liquid pressure is obtained from ANSYS Flotran CFD analysis software for using three oils such as castor oils, olive oil and heavy machine oil. The evaluation of oil pressures through change in the punch speed at constant punch radius. The pressure of oil is acting radially on surface of blank during the process. The radial pressure of oil is controlled by the blank holder pressure. As these two pressures are equal, the deformation of blank is uniform to get a required shape and also it prevents the blank failure during deformation. The pressure of oil depends on punch speed. The oil pressure increases with increase in the punch speed. The oil pressure is the dominant parameter for failure and success of forming of cups from the cylindrical blanks. This pressure of oil is used to evaluate the blank holding pressure. In this paper the numerical studies are carried on the effect of punch speed on oil pressure in hydroforming deep drawing process.

Process Parameter Effects on the LDR in Warm Deep Drawing of Magnesium Alloys

The present work is focused on the investigation of the role of temperature and punch speed in warm deep drawing of AZ31 magnesium alloy. To this purpose, an experimental campaign, defined using a proper DOE approach, has been performed. The experimental results, in terms of the Limiting Drawing Ratio, have shown that drawability is strongly affected by the process parameters. In particular, Limiting Drawing Ratio exhibits the peak value at 250°C. As far as the effect of punch speed is concerned, it depends on temperature: at 200°C drawability increases with decreasing punch speed whilst a reverse behaviour is observed at 250 and 300°C. The experimental results have been analysed by ANOVA in order to evaluate the effect of the single independent factors and their interactions on the dependent one.

Analysis of wear in deep-drawing process of a cylindrical cup

In the present investigation, a deep-drawing process forming a cylindrical cup is simulated using the finite element method to study the wear depth on the draw die arc segment. Both the Blank and the die are assumed to be deformable. For the blank, both the elasto-plastic and elasto-viscoplastic material behaviors are considered, while the die material is assumed to be elastic. The materials are isotropic and Von-Mises yield criterion is employed. Considering the elasto-viscoplastic behavior for the blank, the effect of punch speed on the wear depth of the die shoulder is investigated. Meanwhile, the effects of different process parameters such as the blank holder force, the die radius as well as the clearance between the punch and the die on the wear depth profile of the arc segment of the die are investigated and several conclusive results are presented. The results show to be in good agreement with those cited in literature.

Determination of optimal loading profiles in warm hydroforming of lightweight materials

Abstract In this study, a methodology is developed to determine proper profiles of the hydraulic pressure and the blank holder force under warm hydroforming conditions at different punch speeds. First, finite element models (2-D and 3-D) are developed and validated through comparisons with the experimental results from the literature. To determine the optimal hydraulic pressure and blank holder force profiles simultaneously, an adaptive FE analysis with fuzzy control algorithm was developed. Thinning, wrinkling, punch wall contact, die corner floating and conduction were used as criteria in the fuzzy control algorithm. The effects of the determined loading profiles are then presented in terms of thickness, strain and stress, and temperature distributions as well as success/failure of the forming process. The effect of punch speed was also investigated to reveal its impact on part formability. It was found that the optimal process conditions can be rapidly and accurately obtained with the developed adaptive FEA method coupled with fuzzy control algorithm.

A numerical investigation of air flow during tablet compression

This paper presents a systematic numerical investigation of airflow during compression in a simplified tablet press geometry. Air entrainment during tablet compression has been cited as the cause of manufacturing defects and quality problems. The effects of tablet punch profile, speed and punch to die wall clearance on airflow in the system are investigated. Conditions under which air entrainment in the tablet formulation are likely to occur have been identified, and are found to correspond with punch concavity. For a flat profile punch, the effects of punch speed and punch to die wall clearance are shown to be of minor importance.

Development of shear bands during the perforation of a steel plate

We have analysed the development of shear bands during the perforation of a steel plate by a massive rigid punch. The contact surfaces are modeled as smooth and the steel is modeled as a thermoviscoplastic material that hardens with an increase in the plastic strain and plastic strain-rate but softens due to the rise in its temperature. The effect of punch speed, the clearance between the punch and the back supports, and the radius of the periphery of the punch nose on the development of bands is delineated.

Effects of Punch Speed and Punch Mass on the Dynamic Compaction of Copper Powders

Effects of Punch Speed and Punch Mass on the Dynamic Compaction of Copper Powders