Spring Back Research Articles

Selection of Optimal Bending Types in Die Process of L-Shaped Panels Considering the Springback Behaviours

In die designing, one of the most crucial decisions is selecting the appropriate die process required to produce panels. The challenge for die designer is to comprehend the behaviour of the panel material in relation to the die processes. If the die process is not correctly determined before die fabrication, severe panel spring back may occur, which can become difficult and require additional time and effort to rectify. This paper presents research aimed at understanding the behaviour of different types of bending process combinations concerning the spring back occurrence during the stamping process of an L-shaped design intent panel. Using simulation and experiment, three types of materials with different tensile properties of 270 MPa, 440 MPa and 590 MPa, but the same thickness of 1.8 mm, were selected. The results were compared, analysed and optimized by using Response Surface Methodology (RSM) method. The results demonstrate that one-process bending with full bending (compress type) approach, is the most suitable for the three materials type L-shaped panel. The study provides guidelines for die design engineers, industrial practitioners and researchers to decide on the best approach for die process decisions, when dealing with specific panels properties, shape and thickness.

Simulation and Experimental Approach for Metal Forming with a Multi-Point Die

Multi-point forming (MPF) is considered a flexible and innovative sheet metal forming process that allows for the creation of three-dimensional curved surfaces. This study investigates the effects of various parameters on the final product in metal forming using a multi-point die. The research employs a combination of numerical simulations and experimental work to analyze and minimize defects in the forming process. The concentration is on brass (Cu Zn 65-35) and rubber materials, with specific thicknesses of 0.71 mm and 2 mm, respectively. Although ANSYS 15.0 is used to study the stresses and strains resulting from the formation process with the multi-point die (MPD), the experimental work was conducted to study the effect of two parameters: forming speeds (5 and 15 mm/min) and holding times (1, 3, and 5 minutes were used in this process). The simulation results reveal that the use of rubber significantly reduces defects such as dimples on the sheet surface. Additionally, the presence of rubber helps distribute the force, leading to a reduction in maximum stress and strain in the blank profile to approximately 27% and 49%, respectively, in the second case. The study also explores the impact of forming speed and holding time on spring back. BY measuring the dimensional accuracy of the final products. A forming speed of 5 mm/min and a holding time of 5 minutes resulted in the best outcomes, with a minimum average spring back (0.997). Moreover, the ANOVA algorithm was used to discuss the results which indicated that the forming speed and holding time significantly affect the dimensional accuracy. The research shows that altering settings and adding rubber to multi-point forming improves product quality and accuracy. This study enhances metal forming knowledge and improves industrial processes.

Response of Structure with Spring Back System Bracing Subjected to Seismic Loads

Response of Structure with Spring Back System Bracing Subjected to Seismic Loads

Influence of creep forming temperature on the mechanical properties and high cycle fatigue strength of Al-Mg-Sc-Zr alloy

Creep forming experiments were conducted on 1.6 mm thick sheets of 5024 alloy at an initial stress of 210 MPa in the temperature range 120 to 320°C for 2 hrs. The effect of forming temperature on the spring back behaviour and the mechanical properties of the material was studied. Results showed that spring back is high in the lower temperature range. Exposure to creep forming temperature had a marginal effect on the ultimate tensile strength and yield strength. At the same time, there was significant reduction in the ductility as a result of exposure to creep forming temperature in the range of 200-280°C. The fatigue strength of the alloy for 106 cycles was found to have increased from 250 to 290 MPa after exposure of the material to creep forming temperature of 200°C. Exposure to 300°C, however, did not exhibit a similar trend. Fractography studies on fatigue tested specimens showed delamination along the planes perpendicular to the fatigue crack propagation plane within the fatigue crack initiation zone. Analysis suggests that precipitation of β (Al3Mg2) due to exposure to creep forming temperature regime appears to have been responsible for the observed change in the mechanical properties. Detailed analysis suggests the optimum creep forming temperature for 5024 alloy is 300°C for 2 hours, wherein the alloy shows the least spring back with desirable mechanical properties.

Relationship between Push Depth and Spring Back of Smooth Surface Creation by Electroconductive Burnishing Tool

Relationship between Push Depth and Spring Back of Smooth Surface Creation by Electroconductive Burnishing Tool

Use of Spinning Roller in Cylindrical Densification; Spring back in Black Poplar, Larch and Cedar of Lebanon after Densification

Wood materials have been the solution to many needs throughout history due to their unique positive properties. By improving the properties of wood materials, their areas of use can be expanded and ensured that they are preferred. The densification process is one of the studies carried out to improve wood material properties. With densification, the physical and mechanical properties of the wood material are improved. There are many different methods used for densifying wood materials. While the densification process brings many positive properties to the wood material, an undesirable situation such as spring-back after the process is the negative side of the densification process. In this study, black poplar (Populus nigra L.), larch (Pinus nigra Arnold) and cedar of Lebanon (Cedrus libani A.Rich.) trees were shaped into cylinders on a lathe. After that, densification processes were carried out on the lathe machine using the spinning roller designed and manufactured for this purpose. Densification processes were carried out at 0.081, 0.121, and 0.202 mm/rev feed, at 200 and 400 rev/min, and 0.5 and 1 mm densification depths. The spring-back rates after densification in three different types of cylindrical wood materials were investigated. Theoretical and experimental spring-back amounts of test specimens whose surfaces were densified under different densification conditions were interpreted. When evaluated in general, the highest densification rate was obtained in black poplar wood species, 0.081 mm/rotate feed, 200 rpm spindle speed and 1 mm depth of densification. The lowest spring-back ratio was obtained in larch tree species, 0.121 mm/rotate feed, 400 rpm spindle speed and 1 mm depth of densification. The highest densification percentage was obtained in black poplar tree species, and the lowest in larch tree species. The lowest percentage of spring-back was obtained in the larch tree species and the highest in the black poplar tree species.

Study on the Influencing Factors and Forming Process Selection of Sheet Metal Bending Spring Back Defects

In recent years, with navigation, aviation, chemical manufacturing, and automobile bodies increasing requirements for lightweight, high efficiency, and energy saving, quality requirements in the selection of materials and manufacturing process are also improved. However, there is an unavoidable elastic deformation in the process of plastic bending deformation of the panel veneer, and the accuracy of the workpiece is impacted by the spring back phenomenon, which causes dimensional and shape inaccuracies in the panel veneer. The purpose of this paper is to summarize and analyze the phenomenon of flexural spring back caused by material selection and processing techniques and to discuss the solution of the flexion bounce problem from the material selection, processing method, and machining mold, which can be applied to avoid material wastage.

Assembly and Test Results of the RMM1a,b Magnet, a CERN Technology Demonstrator Towards Nb3Sn Ultimate Performance

As part of the High Field Magnet technology development carried out at CERN, demonstrators are under construction to explore the full potential of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn. The Racetrack Model Magnet (RMM) is one of them, building upon the successful Enhanced Racetrack Model Coil (eRMC) eRMC1a magnet which reached 16.5 T peak field or 16.3 T bore field at 1.9 K. The RMM1a,b magnet is composed of the same two previously tested eRMC racetrack-type coils and an additional middle RMM coil. This central racetrack-type coil features a closed cavity with a diameter of 50 mm and a total length of 526 mm. The coil pack is assembled in the same shell-based support structure as eRMC1a, using bladders and keys to allow for a precise control of the preload with minimal spring back and conductor overstress. The magnet was preloaded with a conservative approach limiting the equivalent peak stress in the coil blocks below 150 MPa. It was then successfully tested up to 16.7 T peak field or 16.5 T bore field at 1.9 K. This paper describes the assembly of the RMM1a,b magnet, relying on Finite Element Analysis (FEA) and mechanical instrumentation, as well as the powering test results at 4.2 K and 1.9 K.

On the Influence from Pressing Agent (PEG) on the Elastic and Plastic Mechanical Behavior of Hard Metal Powder Compacts

During unloading, pressed hard metal powder compacts expand (spring back), leading to unwarranted tensile stresses and, subsequently, crack initiation in the green body. Here, the elastic spring back and the green strength are analyzed for different types and amounts of the pressing agent PEG (polyethylene glycol). The results show that the plastic behavior, but not the elastic behavior, is influenced by a change of the pressing agent PEG. In this context, it should be stated that the risk for the initiation of cracks is influenced by both the elastic and plastic behavior after compaction. The spring back after compaction and the green strength defines to a large extent the risk for cracks. In addition, it is concluded that a standard three-point bending test is sufficient to analyze the risk for the initiation of cracks when comparing different spray-dried powders.

Arthur Marble Aquifer and Te Waikoropupu Springs, New Zealand: flow contributions and nitrate sources

This paper investigates sources of early signs of nitrate pollution in a karst aquifer and major karst spring. Te Waikoropupu Springs are the largest springs in New Zealand and amongst the largest in the Southern Hemisphere with a mean outflow of 13.4 m3/s. They discharge the clearest water ever recorded from a karst spring, but early warning of water quality deterioration is signalled by increasing nitrate concentrations. The springs discharge water from a partly artesian aquifer of 2.85 km3 volume in karstified Ordovician marble with a transmission time averaging 7.9 years. Reservoir porosity is unusually high for a crystalline carbonate rock, estimated as 6%. Water emerging at Main Spring (9.89 m3/s) and adjacent Fish Creek Springs (3.48 m3/s) is a mix of recharge from four main sources. The paper investigates by means of mass balance modelling the proportions of water coming from each source, the origins of nitrate contamination and the contribution of nitrification. Water losses into the bed of the upper Takaka River, about 17 km from the Springs, provide 13% of the mean flow at Main Spring, 34% of the flow at Fish Creek Springs, and 83% of the volume discharged at submarine springs. Infiltration from rain falling over farmed land in the middle valley is estimated to supply 10% of total outflow at Main Spring and Fish Creek Springs but to contribute 82% of the NO3-N output discharged at the springs. Nitrification accounts for 16% of the nitrate discharged. A 34% reduction of leachate concentration in the middle valley would be required to bring NO3-N values at Main Spring back to levels recorded in the 1970s.

Effectiveness of forced cooling during laser bending of duplex-2205

ABSTRACT Duplex-2205 is a dual-phase stainless steel having high mechanical strength and excellent corrosion resistance properties. Large spring back and high heat sensitivity are major problems in duplex-2205 during cold and hot working, respectively. Laser bending process is an advanced manufacturing process that is used for difficult to form materials with minimum heat-affected zone, negligible spring back, and high precision. Forced cooling (FC) has improved the efficiency during multiscan laser bending by reducing the waiting time. This study is focused on the analysis of the effectiveness of FC at the lower surface during single scan laser bending of duplex-2205 stainless steel. Worksheet geometry (thickness and width) and laser parameters (beam diameter, scanning speed and power) are varied to analyze the temperature profile, bend angle, mechanical and metallurgical properties during FC and compared with natural cooling condition. The results showed that a higher bend angle is observed in FC compared to natural cooling. Furthermore, tensile strength and hardness are improved whereas ductility is reduced due to change in phase distribution in the scanning region. Moreover, FC is found to be more effective at higher laser power, lower scanning speed, intermediate beam diameter, lower sheet thickness, and longer width of the worksheet.

Literature Review on Analysis of Spring Back in Sheet Metal Forming Processes

Abstract: The spring back is the part of sheet metal bending that is most susceptible to failure during unbounding. Elastic and plastic deformation combine to completely distort the workpiece (sheet metal) during the metalworking process. When sheet metal is being worked on, it is put under a lot of pressure, which causes plastic deformation. However, when the pressure is released, the material recovers elastically. During the entire process. small amount of reduction in the total deformation takes place So, this phenomenon. is called as spring back-the change in sheet metal's geometry. The thickness of sheet metal ranges from 0.5 mm to 6 mm. Depending on the tooling geometry, material qualities, sheet thickness, and punch and die properties, spring back can affect the completed part's dimensional accuracy. Sheet metal elements / materials / appliances made in industries such as automotive OEM and ancillaries, enclosures aircraft, heavy machinery, medical devices etc. are affected by spring back in their correctness. This review study examines various factors influencing springback in sheet metal fabrication

Seasonal migratory activity of SPODOPTERA FRUGIPERDA (J.E. Smith) (Lepidoptera: Noctuidae) across China and Myanmar.

The fall armyworm (FAW) Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) invaded Myanmar and China in 2018 and greatly impacted agricultural production and ecosystem balance in these areas. FAW is a migratory insect, but its seasonal migration pattern between the two countries has been largely unknown. From 2019 to 2021, we monitored the seasonal migration of FAW in the China-Myanmar border area using a searchlight trap, assessed the reproductive development status of female migrants and traced the migratory routes by trajectory simulation. FAW moths were trapped by the searchlight trap in Lancang County (Yunnan, China) all year, with obvious seasonal differences in the number caught. There were small-scale persistent trapping peaks in spring and summer, and obvious peaks in autumn; only a small number of moths were trapped in winter. Examination of the ovaries of female moths collected in different seasons showed that most females had matured, indicating that the moths were migrating and did not take off from the local area. In the migration trajectory simulation, FAW mainly migrated from Myanmar to Southwest China in spring and summer and back to Myanmar in autumn. Our findings indicate that FAW migrates between China and Myanmar according to the monsoon circulation, which will help guide cross-border regional monitoring and management strategies against this pest. © 2022 Society of Chemical Industry.

Modelling of surface roughness in elliptical vibration cutting of ductile materials

Elliptical vibration cutting (EVC) is a widely used ultra-precision machine technology. However, the surface roughness prediction of EVC is difficult for the complicated surface generation process. In this paper, the surface generation mechanism of EVC is elucidated. A new surface roughness model is proposed considering the roughness in the nominal cutting direction (NCD) and feed direction (FD). The roughness in the NCD is determined by kinematics, tool edge radius, tool flank face interference, and material spring back. For the first time, the influence of material spring back in previous cutting cycle on surface roughness generation is considered in EVC along the NCD. The roughness in the FD is determined by kinematics, tool nose radius, shift distance, tool interference, material spring back and material pile-up. The material spring back is determined by using a function of the plastic strain of workpiece material in the third deformation zone and the minimum undeformed chip thickness. For calculating the roughness component of material pile-up, a function related to tool edge radius, depth of cut, residual height caused by tool nose radius and feed rate is constructed. The experimental results show that the proposed model has a high prediction accuracy. According to the model, the influencing mechanism of various machining factors on the surface roughness variation is clarified and a high-efficiency machining method without deteriorating surface roughness is obtained.

Effects of coating, holding force, stretching height, yield stress, and surface roughness on springback of steel in the V-stretch bending test

Abstract Various types of defects can impact the mechanical or aesthetic properties of stamped sheets, and the phenomenon of springback (SB) is one of them. SB is complicated, and it is hard to simulate it precisely because it is related to many factors such as tooling geometry, material properties, friction, and boundary conditions. In this article, the SB of V-stretch bended samples with uncoated and coated steel is experimentally and numerically investigated. The steel samples are coated with a thin layer of several metals (zinc, tin, nickel, and chromium). This investigation takes into account the influence of various parameters such as the coating thickness, its roughness, the punch depth, the blank holding force (BHF), and the change in the material’s yield strength. A self-developed two-dimensional elastoplastic finite element code was developed using Abaqus/standard. In this work, we also show that the SB angle is smaller for uncoated sheet, higher BHF, higher surface roughness, lower coating thickness, lower stretching height, and lower yield strength.

The material removal and surface generation mechanism in ultra-precision grinding of silicon wafers

The ultra-precision grinding technology based on the workpiece self-rotational principle has been extensively employed to obtain a high surface accuracy and material removal rate during the wafer thinning process. However, no estimation methods and prediction models are currently available for the surface topography of ground wafers, especially considering the material removal characteristics between the grain and silicon. This paper proposed a novel three-dimensional topography modeling framework from a micro-scale perspective to reveal the material removal and surface generation mechanism underlying the wafer self-rotational grinding process. First, the wheel morphology was reconstructed via the random operation for grain position and size, while the combined effects of plastic side flow, elastic spring back and brittle fracture were quantized according to the elasticity theory principle. Then, a new method was developed to calculate the profile height of the wafer topography using kinematic transformation. The groove angle and surface roughness were used to characterize the wafer surface topography. The findings were consistent with the simulation results and validated the correctness of the model. The simulation model was used to examine the impact of the grain size and grinding parameters on the wafer surface topography, while the degree of influence was further evaluated according to the change rate of the groove density curve. This work provided new insights into the material removal behavior during wafer self-rotational grinding and optimized the grinding parameters to obtain a smoother surface.

Evaluation of Deformation Behavior and Fast Elastic Recovery of Lithium‐Ion Battery Cathodes via Direct Roll‐Gap Detection During Calendering

Calendering is the state‐of‐the‐art process for electrode compaction in lithium‐ion battery manufacturing through which the final electrode structure is defined. As the electrode structure determines the electrical und electrochemical transport properties, it is essential to develop a deep understanding of the interdependence between the calendering process and the deformation behavior of the electrodes. Therefore, a novel method for the investigation of the deformation behavior of electrodes, especially the springback (SB) effect, through direct‐gap detection within the calendering machine, is developed. With this installation, it is possible to directly access the maximum compression of the electrodes during calendering. With this approach, two different variations of cathodes, a variation of mass loading and a variation of binder weight content, based on lithium nickel manganese cobalt oxide (NMC622), are manufactured and investigated. Moreover, an empirical model is introduced, allowing the estimation of the SB for NMC622 cathodes considering different mass loadings and cathode compositions. Due to more space for particle rearrangement, cathodes with higher mass loading show a lower SB effect. Adding binder leads to higher plastic deformation and thus lowers also the SB effect of the electrodes.

Theoretical and experimental investigation of the tool indentation effect in ultra-precision tool- servo-based diamond cutting of optical microstructured surfaces.

Ultra-precision tool-servo-based diamond cutting (UTSDC) is a promising technology for fabricating true 3-dimensional optical microstructures. The diamond tool in UTSDC moves alternatively upward and downward along the thrust direction. However, most studies on the material removal mechanism are limited to the orthogonal cutting condition where the depth of cut is invariant. The effect caused by the tool motion in the thrust direction has been overlooked. In this paper, the indentation effect affected by the tool path, tool shape and cutting speed is systematically studied. It is found that the inclined angle between the tool path direction and the main cutting direction plays a key role in the determination of the material spring back and the formation of side burr. The characteristics of indentation force and material spring back indicates that the indentation mechanism is dominant in the cut-in process where the inclined angle is large, while the shearing mechanism is dominant in the cut-out process. A new theory is proposed to explain the tool indentation mechanism in UTSDC, and the simulation results show that the theory can well predict the indentation force under various cutting conditions.

Artificial neural network modelling and optimization of elastic and an-elastic spring back in polymer parts produced through ISF

Artificial neural network modelling and optimization of elastic and an-elastic spring back in polymer parts produced through ISF

Effect ofOrientation on Spring back for Component with Hole and without Hole

Many components are needed to be formed into different shapes depending upon their applications. Whenever the component is formed, it is associated with little or more amount of spring back. It is because of the elastic stresses that remain in the bent-up part. When the bending force is removed, the elastic stresses remaining in the bent up part try to relieve and due to relieving of these elastic stresses the formed up component tries to regain its original shape. This movement of metal due to relieving of stresses is called spring back. In this paper, the effect of orientation on the spring back is studied for components with holes and without holes. The components are formed in U shape along the rolling direction, 450 to the rolling direction, and 900 to the rolling direction, with hole and without a hole in the component. Springback is measured and compared for all the formed-up components. It is seen that the spring back is minimum both for components with holes and without holes formed along the rolling direction. It is also seen that for the components with holes the spring back is reduced as compared with the component without the hole.