Springback Properties Research Articles

Application of the double crank mechanism in designing complex-stroke press

Although having a development history of over 200 years, researches and developments about press machines are still draw interest of modern mechanical engineering. This paper introduces a new press structure that utilizes a double crank mechanism to enhance productivity and efficiency for the stamping process. By adjusting the positions between the component links, the dynamic characteristic of the ram can be modified, optimizing the performance and improving operations of the system. The proposed design also allows for easy adjustments to adapt with different production requirements, such as changing forging and stamping speeds (fast and slow) to avoid the impact of springback properties in sheet metal. The kinematics of the structure have also been determined by mathematic equations, demonstrating significant improvements in the operation of the ram. Results from the research offers a promising solution to enhance production efficiency and enable the creation of simple yet capable mechanisms to perform complex operation.

Development of a springback prediction for a hybrid laminate with sensor functionality

Developing the idea of lightweight construction even further, we have considered the integration of additional functionalities directly into the semi-finished product. Enormous weight savings can be achieved through integration into a large-scale production process. However, these new material composites in the form of hybrid laminates are accompanied by new challenges in terms of forming properties. In particular, there is a need to investigate how the plastic layer with sensor functionality in a hybrid laminate impacts its springback properties. To this end we designed tests using the design of experiments (DOE) technique and identified the significant factors using analyses of variance (ANOVA). Due to the material combination we had to include additional factors such as temperature and punch holding time. Our research showed an adequate distinction between springback and spring-forward behaviour. Utilising FEM, the results were simulated and compared. Our biggest challenge lay in the exact description of the interface between metal and plastic in the FEM.

Experimental investigation, statistical modeling and multi-objective optimization of creep age forming of fiber metal laminates

The experimental assessment of the creep age forming performance of fiber metal laminates was considered in this study. To this end, different fiber metal laminates with the stacking sequence of [Al/02/Al] were manufactured using aluminum alloy 6061 sheets as skins along with E-glass fiber-reinforced polypropylene and E-glass fiber-reinforced polyamide 6 as two different cores. Next, a comprehensive investigation was conducted on the impacts of two main parameters in the creep forming process, i.e. the effect of time and temperature on the spring-back properties of deformed fiber metal laminates. Initially, using the design of experiments and based on the response surface methodology, an imposed spring-back of the creep age formed fiber metal laminates was modeled and the governing linear regression equations were derived and verified. Then, to find the best combination yielding the minimum spring-back, the process inputs (time and temperature) were optimized. The results proved that with an increase in either time or temperature, the spring-backs of the two types of creep age formed fiber metal laminates decreased due to the decrease in elastic strains and the increase of creep strains. Also, to achieve a creep age formed fiber metal laminate with minimum spring-back according to multi-objective optimization in both fiber metal laminates, the most proper values of time and temperature should be taken as 6 h and approximately 160°C, respectively.

Evaluations of tensile properties as a function of austenitizing temperature and springback by V-bending testing in medium-Mn steels

In the present study, tensile and springback properties of medium (3–7 wt%) Mn steels for warm stamping were investigated as functions of Mn content, austenitizing temperature (Taus), V-bending temperature (Tb) and time (tb). For comparison, the tensile and springback properties of 22MnB5 steel used for hot stamping were also evaluated. Whereas medium-Mn steels were air-cooled to room temperature after austenitizing at various Taus, the 22MnB5 steel was water-quenched. The 5Mn steel exhibited the highest tensile properties due to the martensitic matrix with inactive auto-tempering and negligible amount of retained austenite. The springback of medium-Mn specimens was increased by the addition of Mn at a given Tb when tb was 0 s. At the Tb of 300–500 °C, the fraction of martensitic transformation was raised by increasing the Mn content, resulting in high springback. At the Tb of 600 °C, the rise in transformation strain by the addition of Mn raised springback. When Tb was fixed to be 600 °C, the springback of medium-Mn specimens was increased by the addition of Mn due to the increases in transformation strain at the tb of 0 s and the fraction of martensitic transformation during air cooling at the tb of 2 s and over.

Analysis of orthodontic wire springback to simplify wire bending

ABSTRACT Purpose: This study aims to analyse the springback behaviour of commercial orthodontic wires. Materials and methods: The relationship between the predetermined bending angle (x) and the obtained bent angle (y) of commercial stainless steel (SS) and cobalt-chromium alloy (Co-Cr) orthodontic round wires was analysed. The springback value was calculated from the difference between the two angles (x – y). Results: The springback value became larger when (1) the SS wire was used instead of Co-Cr wire, (2) the wire diameter was small, and (3) the curvature radius was large. The relationship can be adequately represented by a linear function in the form of y = ax + b (R 2 > 0.98). Conclusion: By calculating the inverse of the function, i.e. x = (y – b)/a, the necessary bending angle (x) for the desired bent angle (y) can be calculated in advance, thereby obtaining the desired angle in a single bending action. Analysis of the springback property of the orthodontic wire and utilization of the linear function between x and y for a particular shape and composition of wire can help improve accuracy in wire bending.

Effect of thermocycling on surface roughness and springback properties of different orthodontic arch wires: An in vitro comparative study

Objective: Comparative evaluation of surface roughness and springback properties of stainless steel (SS), nickel-titanium (NiTi), copper nickel-titanium (CuNiTi) and Teflon-coated NiTi orthodontic archwires before and after thermocycling.Materials and Methods: A total number of 360 specimens were utilized in this study. For each type of wire, specimens were divided into three groups as follow; Group 1 (control): as-received archwires, Groups 2 and 3: specimens were subjected to thermocycling (500 cycles and 1000 cycles, respectively). Surface roughness (Ra) was determined by using a profilometer. Flexural modulus of elasticity (E) and yield strength (YS) of the wires were measured using a three-point bending test in a universal testing machine. The springback ratio (YS/E) was calculated for each wire. Data were statistically analyzed using ANOVA and Bonferroni post hoc tests (α=.05).Results: For all types of wire, the highest surface roughness was noted with 1000 cycles, followed by 500 cycles and the lowest surface roughness was detected in control group. No significant difference in surface roughness between control and 500 TC group was detected for all types of wire. After thermocycling, the highest surface roughness was noted in Teflon coated NiTi, followed by CuNiTi and NiTi and the lowest values was detected in SS. There was a significant difference in the springback ratio after thermocycling regimens for SS, NiTi and Teflon coated NiTi only (P < 0.001). Conclusion: The thermocycling process can induce changes in surface roughness and springback properties of orthodontic archwires. Stainless steel archwire displayed the least amount of surface roughness after thermocycling and we recommend its utilization in sliding mechanics to reduce friction during orthodontic tooth movement. In spite of higher surface roughness of NiTi-based archwires, the properties of higher springback and wide range of action make them appropriate choices for the clinicians during various stages of orthodontic treatment.

Feasibility of a concept out-of-autoclave carbon fibre reinforced polymer part manufacturing process

Feasibility of a concept out-of-autoclave carbon fibre reinforced (thermoset) polymer (CFRP) part manufacturing process, in which hot forming and curing of prepreg are integrated in one step, was demonstrated. Optimal forming-temperature, dwell-temperature and/or dwell-time with respect to formability, springback and mechanical properties of the formed part were determined for two representative laminate thicknesses of 0.3 and 0.5 mm by V-bend part forming followed by macroscopic observation, Scanning Electron Microscopy and flexural testing of formed parts. Benchmarking against parts manufactured by the traditional autoclave-process demonstrated feasibility of the concept process for manufacturing high-quality parts, principally for lightweight structural automotive engineering applications. Compared to Resin Transfer Moulding, considered the industry benchmark Out-of-Autoclave process, opportunity for reduced manufacturing time to within 300 s per part and through a much more simple process for reduced lead-time, reduced financial cost and greater environmental sustainability, was highlighted.

Simulation on the Springback Property of Sealing Ring in Nuclear Power Plant

In order to simulate the thermal influence on springback property of O-ring, based on elastic-plastic contact analysis method of finite element analysis (FEA), numerical simulation of compression-springback course of O-ring was carried out by ANSYS software. The results show that it causes a sharp decrease in the peak force applied on O-ring, corresponding to a decline on the contact stress distribution which may influence the seal ability of the O-ring. The simulation results are in good agreement with the experimental results.

Effect of Carbon Gradient on the Microstructure and Mechanical Properties of Fe-22Mn-C TWIP/TRIP Steels

High-manganese austenitic steels are promising emerging automotive steels demonstrating high strength and ductility. The main deformation products observed in these steels are mechanical twins and ε-martensite, where the dominant deformation products vary quite strongly with stacking fault energy (SFE), which in turn is a very strong function of the alloy carbon content. In this research, a Fe-22Mn-0.6C sheet steel was decarburized to achieve a variety of through-thickness C gradients, thereby varying the dominant deformation products through the sheet thickness, with the overall objective of producing unique microstructures and mechanical properties. Microstructural analyses after interrupted tensile testing indicated that the amount of both mechanical twins and ε-martensite increased with increasing true strain, where the deformation products changed from mechanical twins at the higher-C core to ε-martensite at the lower-C surface. The spring-back properties of the C graded steels were also compared with reference to the effect of differential carbon concentration gradient.

Investigation of Spring-Back and Spring-Go of AISI 400 S Sheet Metal in "V" Bending Dies Depending on Bending Angle and Punch Radius

The components made of steel sheet metal very important in todays industry. In order to be useful, those parts must comply with the design tolerances, such as shape, position and dimensions. The largest problem with the parts bended by using dies is the springing, because it violates the manufacturing tolerances. Therefore, it is vital to know a parts springback and springgo properties in advance, which is mainly dependent on the properties of the sheet metal and bending conditions.In this study, 0.9 mm AISI 400 S steel sheet metal was bended using V dies (30°, 45°and 60°) and punches (2 mm, 4 mm and 6 mm). After being removed from the bending dies,springback rates of the specimens were measured by using optical goniometer. With respect to the bending angles and punch radii, springback and springgo properties of the specimens were recorded by using a spreadsheet software and some figures are obtained.

Two-scale finite element analyses for bendability and springback evaluation based on crystallographic homogenization method

Abstract In this study, a relationship between the sheet metal formability, such as the bendability and springback property, and the crystal texture was investigated by using our two-scale finite element (FE) analysis code based on the crystallographic homogenization method (Nakamachi et al., 2010 [1] ). Our code employed a two-scale finite element model, such as the microscopic polycrystal structure and the macroscopic elastic plastic continuum, which can predict the anisotropic plastic deformation of sheet metal in the macro-scale, and the crystal texture and hardening evolutions in the micro-scale. The macro-FE model consisted of the die, punch and sheet metal. The die and punch were modeled as the rigid bodies for “V-bending” process analyses. The measured crystal orientation distribution was adopted as the initial texture in the microscopic polycrystal FE model, which corresponded to the three-dimensional representative volume element (RVE). RVE model was featured as 3×3×3 equi-divided solid finite elements, totally 27 FEs with 216 crystal orientations assigned at the integration points of micro-finite elements. The bendability was evaluated by the surface wrinkle growth index and the strain localization – the shear band formation – by using two-scale FE results. On the other hand, the springback property was defined by the angular difference between before and after the punch and die removing process – the post-process. At first, we investigated the bendability of single crystal sheets, which have typical preferred orientations of the copper alloy sheet, to elucidate the fundamental mechanism of shear band formation and wrinkle growth in the V-bending process. Next, we analyzed V-bending processes of four copper alloy polycrystal sheets to evaluate the bendability and springback property. The Cube-dominant texture sheet of the Corson series copper alloy and the {001}〈110〉-dominant texture sheet of the phosphor-bronze alloy show a high-bendability. On the other hand, the S-dominant texture sheet of the Corson series copper alloy and the Brass-dominant texture sheet of the phosphor-bronze alloy show a low-bendability. By contraries, the Cube-dominant and {001}〈110〉-dominant texture sheets have a low-springback property, and the S-dominant and Brass-dominant textures sheets have a high-springback property. Our two-scale FE results of four copper alloy sheets in the V-bending and the post-process were compared with experimental results, and finally the validity of our two-scale FE code was confirmed.

1408 曲げ加工性・スプリングバック特性最適化のためのマルチスケール・プロセスメタラジー解析手法の開発

微視多結晶構造と巨視連続体の2スケールを考慮した結晶均質化マルチスケール有限要素法を用い,高曲げ加工性かつ高スプリングバック特性アルミニウム合金創製のための最適加工工程設計を行う.

Compression and springback properties of hardwood and softwood pellets

A multiple linear regression analysis was carried out to predict the length of pellets under compression in the die based on moisture, temperature, pressure, hold time, and their interaction terms. Excellent correlations were obtained in the dependency of the considered parameters on length of compressed material inside the die. Springback characteristics based on axial changes after the compaction process were analyzed. The expansion for hardwood pellets (16.28%) was found to be lowest at particle size 0.150 to 0.300 mm with 8% moisture (w.b), 60 °C, 139.3 MPa pressure, and a hold time of 15S. The expansion for softwood pellets (20.56%) was lowest with particle size 0.300 to 0.425 mm, at 8% moisture (w.b), 70 °C, 159.2 MPa, and a hold time of 30S.

Creep Age-Forming Experiment and Springback Prediction for AA2524

Creep age-forming (CAF) technology is a new forming method, which combined age hardening and creep forming processes into one. It is mainly used to manufacture wing panels. In this paper, a set of experimental device of creep age forming is developed and the influence of process parameters on the springback of artificially aged 2524 aluminium alloys (AA2524) are investigated. The law of the comprehensive effect of aging time, aging temperature, elastic pre-deformation radius and work-piece thickness, on creep aging springback and mechanical properties of AA2524 is obtained. Based on multiple regression analysis, springback prediction model of process parameters is established and further proven experiments have then been carried out. The result shows that the maximum springback deviation between the experimental results and the prediction ones is within 9.5%. The accuracy of springback prediction model is validated, which provides a theoretical basis for process parameter optimization and springback prediction of CAF.

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.

410 難加工材のスプリングバック特性に及ぼす曲げ線圧縮の効果(機械材料・材料加工IV)

410 難加工材のスプリングバック特性に及ぼす曲げ線圧縮の効果(機械材料・材料加工IV)

Springback properties of single- and poly-crystalline pure aluminum processed by severe plastic deformation

A bending tester with an incorporated high-precision angle sensor was developed in this study. Pure aluminum single crystal and polycrystalline materials were used. Bending properties, especially the springback characteristics of materials as-received and fine-grained using AR and ECAP processes, were investigated. The springback characteristics are discussed based on various mechanical properties that were elucidated by tensile and hardness tests. Consequently, the following results were obtained. (1) AR and ECAP cold-processing refined grains of both single crystal and polycrystalline materials with almost no work hardening exhibited increased Vicker's hardness Hv without a decrease in elongation δ, at an equivalent strain ε of not less than 1.0. (2) The ECAP sample, which underwent many cycles of high strain processing, i.e., being subjected to large equivalent strain ε, indicated a large springback angle δSB. It also turned out that springback angle increased with an increment of δSB=0.1° per cycle of ECAP processing. (3) Both nECAP-s [110] and nECAP-p samples demonstrated a constant springback angle δSB, irrespective of equivalent strain ε at a bending angle of not less than δ=95°. (4) Fine-grained materials show a bigger springback angle δSB than as-delivered materials. Nevertheless, AR and ECAP samples, processed with different strain loading mode, showed little difference in the trend of spring back angle δSB against bending angle δ. (5) Steel materials over a wide range tend to indicate springback angle δSB in direct relation to the n value. However, fine-grained pure aluminum material of this study turned out not to conform to this trend. The result of this series can constitute fundamental data that are useful toward the establishment of a plastic deformation processing method of fine-grained materials.

341 難加工材のスプリングバック特性に及ぼす曲げ線圧縮の効果(加工による機能創製)

341 難加工材のスプリングバック特性に及ぼす曲げ線圧縮の効果(加工による機能創製)

Order/disorder phase composite Fe–Pt film magnets prepared by RF sputtering

Abstract Usage of order and disorder phase transformation enabled us to obtain Fe 50 Pt 50 exchange-spring film magnets. The Fe–Pt films were composed of soft magnetic disorder and hard magnetic order phases. The values of remanence, I r , coercivity, H c , and (BH) max in the film were approximately 1.05 T, 500 kA/m, and 130 kJ/m 3 , respectively. The remanence of the prepared film was enhanced compared with theoretical value for isotropic Fe 50 Pt 50 alloy, 0.7 T. We also confirmed that the above-mentioned films have a superior spring-back property compared to that of Fe–Pt films which are almost composed of order phase.

Predicting springback in sheet metal forming: an explicit to implicit sequential solution procedure

The springback properties of sheet metals make the design of forming dies extremely difficult. In this work a coupled explicit to implicit finite element procedure is outlined for predicting springback deformations in sheet metal forming processes. The explicit method is initially utilized to analyze the contact based forming operation of a production stamping process. Then, an implicit solution is performed to simulate the springback that develops in a blank after the forming pressure has been removed. Using this simultaneous solution technique on an actual automotive component, numerically predicted springback deformations are found to be within 1% of production values. The results of the numerical investigation indicate that the coupled finite element procedure described herein can be utilized to significantly reduce the number of die prototype designs that are currently required in sheet metal stamping operations.