Punch Radius Research Articles

Elastohydrodynamic Lubrication Line Contact Based on Surface Elasticity Theory

Abstract Using surface elasticity theory, this article first analyzes the surface effect on the elastohydrodynamic lubrication (EHL) line contact between an elastic half-plane and a rigid cylindrical punch. In this theory, the surface effect is characterized with two parameters: surface elastic modulus and residual surface stress. The density and viscosity of the lubricant, considered as Newtonian fluid, vary with the fluid pressure. A numerical iterative method is proposed to simultaneously deal with the flow rheology equation, Reynolds equation, load balance equation, and film thickness equation. Then, the fluid pressure and film thickness are numerically determined at the lubricant contact region. Influences of surface elastic modulus, residual surface stress, punch radius, resultant normal load, and entraining velocity on the lubricant film thickness and fluid pressure are discussed. It is found that the surface effect has remarkable influences on the micro-/nano-scale EHL contact of elastic materials.

Contact mechanics of the functionally graded monoclinic layer

In this study, the frictional contact problem of a functionally graded (FG) monoclinic layer was addressed based on the linear elasticity theory. The FG monoclinic layer was loaded by a rigid cylindrical punch that transmits both normal and tangential concentrated loads. It was assumed that the elastic stiffness coefficients varied exponentially through the thickness of the layer. The contact area was assumed to be under Coulomb friction conditions that relate the tangential traction to the normal component. The general expressions of the stress and displacement for the FG monoclinic layer were obtained by applying the integral transform technique. Using the boundary conditions of the problem, a second kind singular integral equation was obtained, and it was solved numerically by applying the Gauss-Jacobi integration formulas. The effect of the fiber angle, the material inhomogeneity, the friction coefficient, the punch radius, material type and the external load on the contact width, contact stress, and in-plane stress were given. This is the first study that investigates the effect of inhomogeneity on the contact problem of monoclinic materials.

Desain dan Analisis Alat Bending V Sistem Hidro Pneumatik

The design of the pneumatic hydro system V bending tool serves as an alternative tool for bending plates replacing the manual bending method which is widely used in the industrial community, especially machining workshop workshops today. In this design the hydraulic jack bender is driven by a pneumatic cylinder so that the workload of the operator is lighter. As for the results of this design and analysis, a V bending tool with 750 mm frame height, 650 mm frame width, 150 mm hydraulic stroke length, and 5 mm diameter spring pull wire are obtained. In addition, the punch angle is 85o and the punch radius is 1.5 mm while the die angle is 85o, the width of the V die is 33 mm and the bending line capacity is 300 mm. The punch and die material chosen is steel AISI 1045.

Elastohydrodynamic Lubrication Line Contact of a Functionally Graded Material Coated Half-Plane

Abstract The elastohydrodynamic lubrication line contact problem between a functionally graded material (FGM) coated half-plane and a rigid cylindrical punch is investigated. The inhomogeneous elastic properties of the FGM coating are expressed by the exponential model. The lubricant between two solids is supposed to be the Newtonian fluid. The fluid viscosity and density are considered to be dependent on the fluid pressure. To determine the unknown film thickness and fluid pressure at the lubricant contact region, a numerical iterative method is employed to simultaneously solve the flow rheology equation, Reynolds equation, load balance equation, and film thickness equation. Influences of the stiffness ratio of the FGM coating, the resultant normal load, the punch radius, and the entraining velocity on the lubricant film thickness and fluid pressure are analyzed.

B EXPERIMENTAL AND FINITE ELEMENT ANALYSIS OF SQUARE DEEP DRAWING PROCESS FOR LAMINATED STEEL-BRASS SHEET METALS

In this paper, the drawability of two-layer (steel-brass) sheets to produce square cup, is investigated through numerical simulations, and experimental tests. Each material has its own benefits and drawbacks in terms of its physical, chemical and mechanical properties, so that the point of this investigation is taking the benefits of different materials, like (low density, high strength and resistibility of corrosion), at the same time and in a one part. ANSYS18 software is used to simulate the deep drawing process of laminated sheet. The deep drawing processes for square cup were carried out under various blank holder loads with different lubrication conditions (dry and lubricant) and with variable layer arrangement. The materials were low carbon steel st1008 and brass CuZn30 sheets with thickness of 0.5mm0and 0.58mm respectively. The thickness of laminated sheet blank was 1.1 mm and its diameter was 83 mm. The drawn cups with less imperfections and satisfactory thickness distribution were formed in this study. It is concluded the greatest thinning appear in the corner of the cup near the punch radius due to extreme stretching take place in this area. Experimental forming load, blank holder load, and thickness distribution are compared with simulation results. Good agreement between experimental and numerical is evident.

Crashworthiness analysis and multi-objective optimization of expanding circular tube energy absorbers with cylindrical anti-clamber under eccentric loading for subway vehicles

This paper presents an investigation of the crashworthiness of expanding circular tube energy absorbers with a cylindrical anti-clamber under eccentric loading for subway vehicles. A finite-element model of energy absorbers is created and validated by two quasi-static experiments, and the strain rate sensitivity is evaluated using standard coefficients of the Cowper-Symonds constitutive model. A parametric study is performed using the validated finite-element models. It is found that the eccentric collision of two energy absorbers has a significant effect on their crashworthiness and leads to a decrease in the specific energy absorption (SEA) and an increase in the peak crushing force (PCF). The structural parameters of the energy absorber, including the wall thickness t, conical angle α, and punch radius rp, have a significant effect on its crashworthiness under different eccentric distances. Sobol sensitivity analysis is employed to analyze the effects of the design parameters (t, α, and rp) on the objective responses (EA and PCF). The results show that the design variables t and α have a greater effect on the sensitivity of the EA and PCF functions for the eccentric distance of h = 0 and 40 mm. The interaction between punch angle α and punch radius rp has significant effect on EA. To improve the crashworthiness of the expanding circular tubes, a multi-objective optimization is applied to achieve the maximum EA and minimum PCF values, and weight factors are introduced to investigate the crashworthiness optimization under single-eccentric loading and multiple-eccentric loading. The optimization solutions of the expanding circular tubes under different single-eccentric loadings have considerable implications. For multiple-eccentric loading, the results show that the crashworthiness of the expanding circular tube energy absorber can be better balanced.

Simulation Study of Deep Drawing Process

Deep drawing process is one of the important processes in sheet metal forming. One of the challenge that faces the deep drawing process is selecting the optimal values of process parameters for the deep drawing process. In order to find the optimum values of these parameters, it is necessary to study their influence on the deformation behaviour of the sheet metal. This paper develops a simulation model for deep drawing process based on Simufact sheet metal forming module to study the effect process parameters on the deep-drawing characteristics. The study also obtained the distribution of strain on the drawn product. Three process parameters are considered in this study namely, punch radius, die radius and clearance, the effect of these process parameter on the required force as well as on the quality of the product are investigated.

Theoretical Investigation of the Bending Process of the Pre-Strained Metal Sheet

During the bending operation of the thin sheet materials by the punch with the near-to-zero radius the special technological operation should be carried out. It means that the metal sheet obtained a certain thinning value, which is usually done in the form of the channel-concentrator or groove by pre-drawing operation in a cold state. It follows to the pre-straining and strengthening of the material. The authors investigated the strain hardened sheet's area after roll forming process theoretically, and obtained the strain-stress distribution inside the sheet during the bending operation. It was found out that the increase of the prior deformation during pre-straining in the bend layer follows to the increase of the radial and tangential stresses and displacement of the neutral axis inside the blank during bending operation. As a result, the bending moment changes its values depends on the punch radius and strain hardening.

A study on experiment and simulation to predict the spring-back of SS400 steel sheet in large radius of V-bending process

The spring-back phenomenon is one of the key problems in sheet metal forming process, especially with a complex shape. In this paper, the experiments of spring back have been first carried out to study the effect of punch strokes (different bending angles) on the spring-back angle for 6 (mm) thickness of SS400 sheet steel by V-bending process. The experimental results are then validated by finite element analysis (FEA) of ABAQUS software. To simulate spring-back of V-bending, deformed results of V-shape from a dynamic forming simulation in Abaqus/Explicit would be imported into Abaqus/Standard, and then a static analysis will calculate the spring-back of V-bending. Simulation studies have shown that there are different variations in the initial bending angle and the spring-back angle after the removal of the bending force based on isotropic and kinematic hardening models. Therefore, the combined hardening model has been proposed to overcome the mismatch between prediction results and the corresponding experiments. Based on the accuracy of FEM simulation, this study also verifies the effect of parameters such as a thickness of the sheet, punch radius and punch stroke on the spring-back angle in order to select the optimum input parameters by using Taguchi method.

Stretch-bending crack simulation for advanced high-strength thick steel sheets considering the contact pressure effect

This paper deals with simulation methods for predicting exact crack position of advanced high-strength thick steel sheets under the stretch-bending condition. The material properties related to anisotropy and hardening behavior were investigated from the tensile test, the loading-unloading and the tension/compression test. The stretch-bending test incorporating DIC ARAMIS system was performed for various punch radii in order to investigate the crack position and the fracture strain. Three simulation methods were established according to the material model and the element type for finding key points for the stretch-bending crack prediction. Simulation results show that the contact pressure effect should be considered for predicting the accurate stretch-bending crack phenomenon. A proposed simulation method can be effectively utilized to the sheet metal forming process design of automotive high-strength chassis parts.

Fracture Investigation in Draw Bending of AZ31B Sheets using Fuzzy Logic Prediction

Automotive and aircraft industries are facing an increased demand of light-weighted materials for reducing fuel consumption and CO2 emissions. Magnesium alloy sheets are considered in manufacturing components of complex geometries and with flexible processes. Fracture investigation of AZ31B alloy sheets is of interest in continuous bending processes to achieve better formability. Certain forming processes of AZ31B sheets are restricted due to its limited ductility at room temperature. Draw bending of AZ31B sheets provides us the necessary forming state to investigate fracture limits. Our investigation relies on data extracted from draw bending tests organised according to a design of experiments plan. The experimental studies were conducted for different punch radii, traverse speeds and rolling directions. The predicted fracture behavior via Fuzzy Logic provides essential data to the setup procedures needed for our subsequent research, which is focusing on reducing the limitations of AZ31B sheets formability.

Desain Konstruksi Press Tool Sebagai Alat Bending Bentuk V Dengan Garis Bending Max. 300mm

Nowadays, the process of metal forming in the machining industry and welding workshop is developing very rapidly especially in the plate bending process. The bending process is the formation of metals which generally use plates or rods of both ferrous and non-ferrous metal materials by bending, which in the bending process will cause stretching or stretching on the neutral plane axis along the bending area and produce a straight bend line. The use of appropriate technology machines has been widely used to increase productivity, efficiency, and effectiveness in the production process for community businesses, especially those in the regions. One of the appropriate technologies that might be applied in the bending process is a hydraulic jack press that is equipped with a press tool. Press tool is one type of product forming, cutting and bending tools from the basic material of sheet plates whose operations are using a press tool. The results of the design of press tool bending tool V have a length of 300 mm bending line, 33 mm bending width, 110 mm spring height, free step distance of 19 mm. The punch angle used is 85⁰ with the punch radius used is 1.5 mm while the die angle is 85⁰. The selected punch and die material is Steel AISI 1045 HV HR.

Pengaruh Sudut Punch dan Ketebalan Pelat terhadap Springback pada Bending V

The bent plate is inseparable from the phenomenon that determines the size of the resulting bending angle. This phenomenon is called springback. Springback is a condition that occurs on a sheet plate when bending is done where after the punch load is removed the bent sheet plate has a tendency to return to its original form. Mini brake bending V tool with a hydraulic jack system produces springback of 1-5 degrees for punch angle 85 ° radius 2.5 mm and carbon steel material St 42 at thickness 3, 4 and 5 mm. Therefore, this study was conducted to find out how the influence of punch angle and plate thickness on springback. The limitation problem in this study is the thickness of the plates used 2 and 4 mm. The type of method used is bending V bottoming with a die angle of 90 °, the punch angle used is 80, 85, and 90, the punch radius used is 2, 4 and 6 mm, and the plate material used is carbon steel. The research method starts from designing die set, punch and die test aids, and making test specimens, then bending test, bending angle and springback measurements are carried out. Based on the research conducted, the greater the punch angle, the smaller springback produced and the thicker the plate, the smaller springback produced tends to be smaller, where the smallest springback is obtained on a plate thickness of 6 mm with a punch angle of 90 ° 4 mm radius obtained -0.31o.

V-shaped bending of Ti-6Al-4V titanium alloy sheet with elliptical hole

The internal elliptical hole defect in the Ti-6Al-4V titanium alloy sheet strongly affects the material mechanical properties during the bending process. In this study, the finite element method (FEM) is used to study the effect of internal hole on mechanical properties of the sheet subjected to the V-shaped bending. The fracture damage, the equivalent strain and the principal stress in the sheet with elliptical hole (the defect sheet) and the hole-free sheet (the perfect sheet) are analyzed contrastively under different punch speeds and radii. The results show that the load in the defect sheet and the perfect sheet has different trends during the bending process. Compared to the perfect sheet, both the damage and the equivalent strain in the defect sheet obviously increase, and the distribution of the principal stress in the bending zone of the defect sheet has a significant change. The hole causes the different evolution of the maximum damage, the equivalent strain, and the maximum tensile and compressive stresses with the increase of punch speed and radius for the defect and perfect sheets. The current results serve a feasible approach to predicting the fracture of the sheet with internal hole during the V-shaped bending process, and provide a guidance for the V-bending experiments of the defect and perfect sheets in the subsequent work.

Designing and Manufacturing the Press Tool of Air Bending V Brake

Nowadays, the metal forming process in the welding machinery and machinery industry is developing very rapidly, especially in the bending process. The buckling process is a metal formation which generally uses sheet plates or rods from both ferrous and non-ferrous metals by bending, which in the bending process will cause a stretching or stretching on the neutral axis of the field along the bending area and producing a straight bending line. Appropriate technology machines have been widely used to increase productivity, efficiency, and effectiveness in the production process for community efforts. One of the appropriate technologies that can be applied in buckling is a tool equipped with a press tool. Press tool is one type of tool for the formation, cutting and bending of products from the base material of sheet plates whose operation uses a press machine. In this study, a V brake bending tool has been produced which has a capacity that is bending line length 300 mm, bending width 33 mm, spring height 110 mm, free step distance 19 mm, spring load received 263,820 N and material capacity that can be bent is a thickness of 3 mm, the punch angle used is 85⁰ with a punch radius used which is 1.5 mm while the die angle is 85⁰

An experimental analysis of the relationship between the corner, die and punch radii in forming isolated flanged shrink corners from Al 5251

Abstract Knowledge of geometry based forming limits would be beneficial early in the product development process to enable design for manufacture in sheet metal forming process. This paper investigates the influence of corner, die and punch radii on the limiting part depth for drawing an isolated flanged shrink corner from aluminium sheet with and without a blank holder. Trends are identified to establish whether complex component geometry can be analysed to provide a guide for process limits for drawing. The failure draw depth is determined experimentally with a configurable tool for 96 different drawing scenarios. A further 432 scenarios were analysed using a validated Finite Element model. The results demonstrated that a trend could be obtained through plotting the failure draw depth against the average radii of a shrink corner. Assuming this can be extrapolated to full parts, the trend could be useful in the early stages of component design to guide decision making for the components shape and selecting the most appropriate manufacturing process.

Experimental characterization, analytical and numerical investigations of metal/polymer/metal sandwich composites – Part 2: Free bending

In this article, we continue the investigations on the forming behavior of the steel/polymer/steel (SPS) sandwich composites as introduced in Part 1 [1]. In this paper, the main focus lies on bending conditions, validated by analytical and numerical methods. A wide variety of SPS layer configurations and thicknesses were tested under three-point bending conditions considering different bending angles (60, 90 and 150°) and different punch radii (1.5, 3, 6 and 12 mm). The results are validated in terms of the bending forces, springback degree, strain field distribution, and thickness reduction, where a good matching between the numerical and analytical results with the experimental ones was reached.

Numerical Simulation of Bending Process for Steel Plate Using Finite Element Analysis

Defects in bending processes are inevitable due to the plastic deformations created through the material pressing. Cost-effective and good quality of the V shaped die plate bending products can be produced by reducing the bending load, springback, and residual strains. In this article, a plate bending process is employed for Hy-80 steel and 304 stainless steel. A 3D explicit/dynamic finite element model is utilized for analyzing the V shaped die plate bending process. Punch load, springback, and residual strains behaviors are studied by applying various punch radiuses and plate thicknesses. The springback and residual strains behaviors are successfully predicted with respect to punch radius and plate thickness. Although bending load has a significant effect on bending process, the springback and residual strains behavior can be estimated according to the value of punch radius and plate thickness. Springback is reduced when the punch radius decreases and plate thickness increases. Recorded residual strains at the tension side were greater than at the compression side.

Production of Large Disks from Cylindrical Blanks by Plastic Deformation. 4. Deformation of a Protrusion by an Annular Punch

The deformation of a protrusion by a peripheral annular punch is mathematically described. The protrusion is formed as a result of central-punch introduction in the manufacture of large disks or hard-to-deform disks by plastic deformation. The maximum force at the end of deformation is found. The relative radius of the annular punch ensuring equal stamping forces for the central and annular punches is determined.

Deep drawing of a stellar shape using finite element simulation and experimental

The process of deep drawing of complex shapes is a difficult process compared to the process of drawing simple shapes such as cylindrical, square and rectangle because of the complex shape is subjected to the higher stresses concentration compared to simple shapes. This work aims to study the effect of the wall corner radius of punch and radial clearance on deep drawing operation using the experimental work and numerical simulation. In this work, an analysis of the deep drawing process is performed for process design of stellar cup drawing. A deep drawing die was designed and manufacturing to perform the experimental procedure required to produce a stellar cup with inner dimensions (major axis equal to 43.7 mm and minor axis equal to 36.64 mm) formed from a circular flat sheet (80 mm diameter) comprised of low carbon steel of (0.08%) carbon content, without any intermediate annealing. A commercially finite element program code (ANSYS 18.0) is utilized to simulate the stellar deep drawing operation. From the comparison between the results, it has been found that the thinning at cup corner increases by decreasing the wall corner radius of the punch and the maximum thinning with the wall corner radius of the punch equal to ( 16Rcp'> = 2 mm) at the corner of the minor axis of completely drawn cup