Integrated Machine Vision System for Evaluating Hole Expansion Ratio of Advanced High-Strength Steels

In this paper, we propose a new method to estimate the hole expansion ratio (HER) using an integrated analysis system. To precisely measure the HER, three kinds of analysis methods (computer vision, punch load, and acoustic emission) were utilized to detect edge cracks during a hole expansion test. Cracks can be recognized by employing both computer vision and a punch load analysis system to determine the moment of crack initiation. However, the acoustic emission analysis system has difficulty detecting the instant of crack appearance since the magnitude of the audio signal is drowned out by noise from the press, which interrupts the differentiation of crack configuration. To enhance the accuracy for determining the HER, an integrated analysis system that combines computer vision with punch load analysis, and improves on the shortcomings of each analysis system, is newly suggested.

The Deep Drawing of a Flanged Square Hole in Thin Stainless Steel Sheet

To manufacture metal products of accurate size and shape by deep drawing requires the precise control of a number of variables. The problem of spring-back after the load has to be avoided, and the prevention of cracks in the product requires careful control of the punch load. In this study, where drawing experiments and simulations were carried out on thin sheets of SUS304 stainless steel, the influence of the scale effect on the thin sheets also needed consideration. This was accomplished by the use of an updated Lagrangian formulation and finite element analysis. Material behavior was simulated using a micro-elastoplastic material model, the performance of which was compared with that of models involving conventional materials. The Dynaform LS-DYNA solver was used for simulation analysis, and pre and postprocessing were carried out to obtain material deformation history as well as to determine thickness change, distribution and material stress, and prepare strain distribution maps. Scaling was necessary to account for the effect of the thickness of the sheet and the relationship between punch load and stroke, the distribution of thickness, stress and strain, and the maximum size (d) of the flanged hole and the maximum height of the flange. The simulation results were compared with experimental results to confirm the accuracy of the three-dimensional finite element analysis of the elastoplastic deformation. The results showed that the size of the fillet radius of the hole (Br) had an effect on the punch load, which increased with an increase in Br. However, the minimum thickness of the formed flange decreased with an increase in Br. The maximum principal stress/strain and height of the flange also increased with an increase in Br. The punch fillet radius (Rp) also had an impact on the process. The punch load decreased with the increase in Rp, while the minimum thickness increased slightly. The average values of the minimum thickness for three models were 0.148, 0.0775, and 0.0374 mm. The forming ratio also had an influence on the process. When the forming limit of the square hole flange was FLR = 0.84, cracking occurred in the corners of the flange, and wrinkles formed over the undrawn area of the sheet. These findings can serve as a valuable reference for the design of deep drawing processes.

Optimum Rotational and Traverse Speeds of Al-Cu Joints Welded by FSW Based on the Formability of The Joint

Joining of aluminum to copper using Friction Stir Welding (FSW) is a primary manufacturing process that is in most applications followed by a secondary forming process. The objective of this research is to determine the optimum rotational and traverse speeds of Al-Cu Welded by FSW based on the formability of the joint. The formability and strength of Al-Cu joined by FSW are investigated under different operating conditions. Aluminum and copper blanks are welded at three different rotational speeds that are 910, 1280 and 1700 rpm, under three different traverse speeds, which are 16, 29 and 44 mm/min. The base metal used in this study is Aluminum (Al-1050) and copper under two conditions, i.e. as received and annealed. The mechanical properties of base metals and produced joints are evaluated by tensile and hardness tests. The Al-Cu joints by FSW are drawn into flangeless U and cup shapes in order to examine the formability of the joint. The maximum tensile load, punch load and forming index were obtained when Al is welded to annealed Cu at 1700 rpm and 16 mm/min, i.e. highest rotational and lowest traverse speeds, and that is due to the strain hardening of the joint. However, the ductility was maximum at 1280 rpm and 44 mm/min, i.e. moderate rotational and highest traverse speed. It can be concluded that if the Al-Cu joint by FSW will be used further in a forming process, it should be welded at a moderate rotational and high traverse speed in order to avoid strain hardening and improve the ductility of the joint.

Deformation Behavior of Al/Cu Clad Composite During Twist Channel Angular Pressing

The research and development of modern metallic materials goes hand in hand with increasing their lifetime via optimized deformation processing. The presented work deals with preparation of an Al/Cu clad composite with implemented reinforcing Cu wires by the method of twist channel angular pressing (TCAP). Single and double pass extrusion of the clad composite was simulated numerically and carried out experimentally. This work is unique as no such study has been presented so far. Detailed monitoring of the deformation behavior during both the passes was enabled by superimposed grids and sensors. Both the sets of results revealed that already the single pass imparted significant effective strain (higher than e.g., conventional equal channel angular pressing (ECAP)), especially to the Al matrix, and resulted in notable deformation strengthening of both the Al and Cu composite components, which was confirmed by the increased punch load and decreased plastic flow velocity (second pass compared to first pass). Processing via the second pass also resulted in homogenization of the imposed strain and residual stress across the composite cross-section. However, the investigated parameters featured slight variations in dependence on the monitored location across the cross-section.

Optimum Clearance in the Microblanking of Thin Foil of Austenitic Stainless Steel JIS SUS304 Studied from Shear Cut Surface and Punch Load

An extrusion-type fine blanking with a negative clearance was proposed by the authors instead of standard fine blanking for creating a full-sheared surface in the micro blanking process. In this study, micro blanking experiments and finite element analyses with narrow, zero and negative clearances are carried out for the optimizing the clearance at which a shear cut surface can be finished with a full-sheared surface with the minimized punch load. Fracture criterion, hydrostatic stress and maximum punch stress for the conditions with various clearances are investigated. As a result, it was clarified that the clearance at which the cut surface does not fracture and minimization of the punch load is achieved is gained by the use of clearance −4 μm.

The non-isothermal hot deep drawing of AA5083 aluminum alloy

The present work is focused on the hot deep drawing process for cylindrical 5083 aluminum alloy parts, by superimposing a thermal gradient between the blank center-flange region. The imprtance of application of forming processes at elevated temperatures, in improving the formability, has increasingly attracted attention in recent years. As a case study, the experimental and numerical tests were performed at three speeds (60, 200 and 378 mm min−1) from room temperature (RT) up to 0.9 melting point, inspired by the advent of extraordinary superplastic behavior of AA5083 in hot condition. In particular, the focus was on the effects of forming speed on punch load, thickness distribution, and earing behavior. Finite element simulations were run in order to investigate the limiting drawing ratio and temperature gradient. The tests highlight that by increasing the temperature, the number and the position of the ears are constant, while the height of ears decreases. Furthermore, limiting drawing ratio equal to 2.84 is reached at 550 °C.

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.

Miniature Hemispherical Bowl-Shaped Forming Using SLA Punch and Die: Modeling and Experimental Analysis

Forming processes are a convenient means for bulk production of parts. These parts are used in a wide range of applications from automotive industries to micro-devices in bioengineering. Manufactured parts are required to be precise in their final dimension, and since the billet material undergoes significant plastic deformation during forming, billet material characterization and prediction of final form is essential. In this study, miniaturized bowl-shaped samples of 3003-H14 aluminum alloy were formed using a die and punch manufactured using the stereolithography (SLA) additive manufacturing method. Tensile testing was performed in order to characterize the material properties of the SLA resin. Using the SLA-created die and punch, hemispherical bowl-shaped forms were generated. In order to investigate possible small size effects, experimental load versus displacement results were obtained for billet plate thicknesses of 0.4–0.8 mm. A numerical finite element model was developed to predict the required punch load to manufacture various thickness bowl-shaped forms. A comparison was made between the load verses displacement curves for the different thicknesses, and the numerical model was validated by the experimental results. The validated computational model can then be used to predict the process parameters prior to starting bulk production. Finally, a model with grains was developed and simulated to show the virtual microstructural morphology of the circular plates before and after the forming operation.

Effect on Blank Holding Force on Blank Deformation at Direct and Indirect Hot Deep Drawings of Boron Steel Sheets

This study involves performing direct and indirect hot press forming on ultra-high-strength steel (UHSS) boron steel sheets to determine formability. The indirect hot press process is performed as a cold deep drawing process, while the direct hot press process is performed as a hot deep drawing process. The initial blank temperature and the blank holding force are set as parameters to evaluate the performance of the direct and indirect deep drawing processes. The values of punch load and forming depth curve were obtained in the experiment. In addition, the hardness and microstructure of the boron steel sheets are examined to evaluate the mechanical properties of the material. The forming depth, maximum punch load, thickness, and thinning rate according to blank holding force were examined. The result shows that a larger blank holding force has a more significant effect on the variation of the thickness and thinning rate of the samples during the drawing process. Furthermore, the thinning rate of the deep drawing part in with and without fracture boundary was respectively examined.

STUDY OF HOLLOW STEMMED HIP BONE FORMING

This study investigated hollow stemmed hip forging for enhancing the biocompatibility of Ti-6AL-4V titanium alloys. Instead of using the expensive titanium billet, this study applied DEFORMTM 3D finite element analysis software to simulate and analyze stem forming with respect to different die temperatures, friction factors, punch types, forging velocities, and billet temperatures. On the basis of its shape, a punch can be classified as flat head, ladder shaped, spherical, and conical. These differences affect the effective stress and punch load after stem formation. The experiment parameters were determined using the Taguchi L16 (45) orthogonal table. Both the simulated and experimental results indicated that the error for the size of the bone stem was less than 2%.