Papers by Keyword: Spring-Back

Abstract: Single point incremental forming (SPIF) process is used to deform complex shapes. Through SPIF process metallic sheet is formed. The formability of a AA5052 is evaluated using SPIF method for industry level product. The utility of SPIF is broad in industries because of the simple operating system of manufacturing and designing metal substances throughout computer design combined with the CNC machine. While forming Mantellic sheet there are many benefits. This process is extensively adopted in automobile, aeronautical, and medical industries for engineering complex parts. In this paper, the main objective is to examine the formability of AA5052 aluminum alloy raw material with various wall angles and operating boundaries using the modified computer numerical control (CNC) milling machine. Here, the shape correctness and the surface roughness are focused for computing the forming depth, wall angle, and spring-back for obtaining improved parts with a proper material with finish surface. For verifying the real-time experiments and evaluating the existence of stress, strain, and thickness variations.

Abstract: Stretch-flanging commonly appears at the concave edge of the panel part. Sheet thickness tends to decrease at the center of flange attributed to the outflow of metal flow, and hence causes a radial shrinking of the material. This shrinking pulls the ends of the flange and makes the adjacent surface overcrown. In this paper the effect of punch profiles on a laboratory scale profile, which assimilates the front fender part adjoining the head light, was investigated for the stretch-flanging process. Both the concave and convex punch profiles were considered. SUS 304 stainless steel sheet of 0.6 mm thick was used as the model metal sheet. DynaForm software was used in simulating the stretch flanging process and followed by experimental verification. The results show that a depression angle of 4.4° and an elevation angle 2.6° can produce lowest crown-contour for the concave and convex punches, respectively. The concave punch also causes less thinning at the flange center which makes it a favorable solution than that of the convex punch.

Abstract: The Yoshida-Uemori combined kinematic and isotropic hardening model is widely applied to numerical prediction of spring-back during sheet metal forming process. With the experimental plastic behavior of aluminum alloy AA5182-O sheet under single cyclic loading, the semi-analytical method was presented to calibrate the parameters of Yoshida-Uemori hardening model. Meanwhile, an inverse identification method was suggested by parameter optimization for minimizing the error between the experimental and predicted results. By comparing the two methods, the Yoshida-Uemori hardening model identified by inverse method is found to be more accurate for description of the Bauschinger effect than the one identified by semi-analytical method, especially for transient softening phenomenon.

Abstract: Based on the requirements of automotive closure for production process and service performance, the property requirements of aluminum alloy sheet for automotive closure, including aging resistance stability, formability, bake hardening, dent resistance, flanging ductility, painting compatibility, etc., as well as introduced their test methods, evaluation characterization parameters, and the pre-aging process were discussed in this paper. Specially, the influential factors and control methods of spring-back of aluminum alloy sheet was discussed. The effect of the pre-aging process on the aging resistance stability and bake hardening of the aluminum alloy sheet for automotive was analyzed, and the property evolution of aluminum alloy sheet under industrial pre-aging process studied. The orange peel and roping phenomena of Al-Mg-Si alloy sheet after deformation were summarized as well.

Abstract: Modeling of the cold flow forming process for manufacturing of tube shaped solution annealed H30 Aluminum alloy has been considered in this present study. Three inputs (feed-speed ratio, roller in-feed and roller axial stagger) and three outputs viz. spring back, ovality and internal diameter have been considered for the present study.. Adaptive network-based fuzzy inference system (ANFIS) in Matlab platform has used for modeling purposes and its performance is compared with regression model. ANFIS has completely outperformed the regression models. Percentage accuracy in predicting all the three responses are found to be very high with ANFIS models. Prediction of ovality against the test data using regression analysis is found to be extremely erroneous. It indicates that additional process parameters are involved in predicting ovality which are not captured during the experimentation.

Abstract: Roll forming is a highly useful and important forming technique for sheet metal. As an economic profile product, roll forming products are widely used in transportation, engineering machinery, and civil construction because of their uniform sections, high strength, and low energy consumption^[1]. Roll forming is a rapid processing operation used for transforming flat sheets of material into useful profiled sections. However, a lot of components used in the automobile, railway cars, ship construction, and building industries have variable cross sections. Therefore, flexible roll forming was developed recently to produce variable cross section profiles.

Abstract: This study, based on finite element analysis, analyzed the spring back phenomenon and stress distribution of forming sheets (HTS) in the roll forming process. By comparison of the stress distribution, this study analyzed two kinds of simulation. The first simulation performed simple bending simulation before roll forming simulation. With reference to the first simulation results, the second simulation analyzed the relationship between the stress distribution and the phenomenon of spring back. We also studied the stress distribution effect for spring back in the forming sheet.

Abstract: High strength steel (HSS) was used as raw material in the automotive industry, which required lightweight and high strength, such as chassis and etc. However, the strength and hardness of the steel are relatively high, leading to the low permeability and large spring-back occurring after forming operation. As a result, the work piece is not shaped desire. This research proposes neural network for predicts the spring back values, in U-bending process, that the materials were differences in mechanical properties, such as SPFH590 (JIS) and SPEC980Y (JIS). In the experiment, the input factors for predictable data consists as the punch radius (RP), die radius (Rd), clearance (Cl) and counter punch force (Fc). After that, the input data were analyzed relation with spring-back values by the Pearson Correlation of One-tailed. Next, It was selected by Leave-one-out and k-fold Cross validation (K-fold and LOOCV), to improve efficiency of the prediction process. Moreover, the result was a measurable performance with Root Mean Square Error (RMSE) technique, equal to 0.788 and 2.10 respectively. In the final analysis, the neural network is effective to predict the Spring-back values of SPFH590 (JIS) rather than SPEC 980Y (JIS) in U-bending process.

Abstract: Cold roll-forming of metal sections is a significant field in advancing forming of strip metal, and the forming processes are influenced by many factors. The scientific design of passes is worked out by combining theoretical analysis with finite element analysis, in accordance with the principles of cold roll-forming; thus the desired high-quality bending sections are achieved through a combination of theory and practice. This study mainly addresses the velocity of the rolls for sheets that have angle sides, and the spring-back of SGARC 440 alloy sheets in the roll forming process, where we use DEFORM to simulate the sheet.

Abstract: With the current development of hot stamping technology, quality products have been striving for not only uniformity in hardness but also a minimum of springback. Considering the fact that the uniformity distribution of hardness and the randomness distribution of the springback are inevitable in hot stamping process due to many complex factors such as contact sequence, contact clearance, scale and initial stamping temperature, a new method named RCP method was proposed to improve the hardness and springback of hot stamping product in this paper. The cooling rate control before stamping is applied based on CCT curves through a rapid air cooling device which can provide cooling rate of 60°C/s. Three parameters included initial stamping temperature, contacting pressure and dwelling time have been investigated in this paper. According to the experiment results, the hardness deviation is markedly decreased and the springback can be controlled within the threshold value ±0.5mm.