New Manufacturing Process and Product Developments in Metal Forming Industry Using Finite Element Modelling and Optimization Techniques

The objective of this paper is to outline a practical approach using numerical modelling and optimization techniques for process and product developments in metal cold rolled forming industry. The optimum economic viability in manufacturing industry requires a minimization of the amount of material used while the structural performance of a cold roll formed product relies on maintaining the stiffness and strength of the section in applications. This leads to the development of new cold forming processes and alternative cold roll formed profiles searching for the optimal profile. In this paper, a Finite Element modelling approach was utilized to simulating complicated manufacturing process and products and optimization techniques including Design Of Experiments was used to optimize the shape design of the end products to obtain lighter products while maintaining the product strength. These developments were illustrated through two case studies of Hadley Industries plc which included (1) numerical modelling of a novel Ultra STEEL® cold roll forming process, and (2) optimization of cold roll forming sections.

Effect of Geometrical Factors on Torsion in Cold Roll Forming of the Lower Side Beam of a Car

Cold roll forming is a continuous metal forming process used to produce a large variety of profiles. A significant product of cold roll forming is asymmetric profiles, whose application is expanding in the construction of cars, houses, bridges, etc. Torsion is one of the common defects in the cold roll forming process of asymmetric section steel and sometimes seriously affects cold roll forming products. With the development of the economy and technology, many asymmetric cold roll-formed parts are being gradually applied to automobiles. Three-dimensional finite element analysis models of 12 stands with 700L sheet material were carried out using the professional COPRA RF and MSC MARC software, taking the lower beam of an automobile as the research object. Five geometric factors of the lower side beam were researched, and the influence rules of different geometric elements on the forming torsion were analyzed. We found that with the increase of web width, flange width, and vertical edge height and the decrease of the corner radius and strip thickness, the torsion defects of cold roll forming were improved to different degrees. The results also showed that the width of the flange has the most significant effect on torsion.

A Method for Rapid Prediction of Edge Defects in Cold Roll Forming Process

In order to implement rapid prediction of edge defects in the cold roll forming process, a new analytical method based on the mean longitudinal strain of the racks is presented. A cubic spline curve with the parameters of the cumulative chord length is applied to fit the corresponding points and center points of different passes, and fitting curves are obtained. As the cold roll forming is micro-tension forming, the tensions between racks are ignored. Then the mean longitudinal strains between racks are obtained. By comparing the mean longitudinal strain between racks and the yield strain of the material, we can judge whether there are defects at the edges. Finally, the reasonableness of this method is illustrated and validated by an example. With this method, the roll forming effect can be quickly predicted, and the position where a greater longitudinal strain occurred can be determined. In order to prevent the defects, the deformation angles need to be modified when the result is beyond the yield strain. To further prove the correctness of the theory, the results of the analytical method are compared with the ones of the non-linear finite element software ABAQUS. The analytical results have the same trend as the finite element results. This method can provide useful guidance to the actual design process.

Effect of Plastic Anisotropy and Process Parameters on the Final Geometry of U-shaped Product in Cold Roll Forming

Since the cold roll forming process is currently used in the production of different sections, it is necessary for manufacturers to further improve the quality of these products. Therefore, it is essential to study various factors influencing the production of these products in detail and provide effective solutions to reduce the factors causing defects in such products. This paper investigates the effect of plastic anisotropy and various factors such as strip thickness, the inter distance between stands, web width, and angle increment on the longitudinal bowing and then compares the results with the practical experiments. Accordingly, a model considering the effect of these parameters on the longitudinal bowing of the final section is considered with the accuracy of 88%. The results show that strip thickness and the increment angle at each stand, and the web width have the most influence on the longitudinal bowing, while strip anisotropy and the inter distance has the least effect on bowing.

Experimental and numerical investigation of the effect of holes on the springback in cold roll forming of UHSS

Ultra-high strength steel (UHSS) pre-notched sections are getting growing popularity in the automotive industry with the development of automotive lightweight. However, the springback of UHSS products is large, and the existence of holes also has an effect on the springback. Accurate prediction of springback of UHSS pre-notched products in cold roll forming ( CRF ) is a key issue to be solved. In this paper, the effect of holes on the springback of UHSS in CRF is discussed by simulation and experiment. The finite element model of pre-notched car threshold was constructed, and its accuracy was validated by continuous CRF experiment. The mathematical model of variable elastic modulus determined by tensile tests of martensite (MS) 1300 was applied in finite element model. The accuracy of springback was improved by 15% in the hole region by using variable elastic modulus . Several forming schemes were designed to research the effect of different features on the springback in the hole region. The results show that the existence of holes reduces the springback and the effect is different at different positions of the car threshold. The springback in the hole region decreases with the increase of the number of stands, the strip thickness and the hole diameter, and with the decrease of the distance between stands and the distance between holes. This study provides a help for reducing the influence of holes on the springback and improving the forming precision of pre-notched sections in the actual production of CRF.

Experimental and Numerical Investigation of AA5052-H32 Al Alloy with U-Profile in Cold Roll Forming

The cold roll forming process is broadly used to produce a specific shape of cold-roll formed products for their applications in automobiles, aerospace, shipbuilding, and construction sectors. Moreover, a proper selection of strip thickness and forming speed to avoid fracture is most important for manufacturing a quality product. This research aims to investigate the presence of longitudinal bow, the reason behind flange height deviation, spring-back, and identification of thinning location in the cold roll-forming of symmetrical short U-profile sheets. A room temperature tensile test is performed for the commercially available AA5052–H32 Al alloy sheets using Digital Image Correlation (DIC) technique, which allows complete displacement and strain data information at each time-step. The material properties are estimated from the digital images using correlation software for tested samples; the plastic strain ratios are also calculated from samples at 0°, 45°, and 90° to the rolling direction. The tested sample’s surface morphology and the elemental analysis are conducted using scanning electron microscopy (SEM) method and energy-dispersive X-ray spectroscopy (EDS) analytical technique combined with element mapping analysis, respectively. The cold roll forming experiments are systematically carried out, and then finite element analysis is utilized to correlate the experiment with the model. The performed cold roll forming numerical model outcome indicates a good agreement with the experimental measurements. Overall, the presented longitudinal strain was observed to influence the geometry profile. The spring-back is also noticed at the profile tail end and is more pronounced at high forming speed with lower strip thickness. Conversely, while the forming speed is varied, the strain and stress variations are observed to be insignificant, and the similar results also are recognized for the thinning behavior.

Off-field transportation and storage of corn stover with medium-high moisture content based on the multistage continuous cold roll forming method

The moisture content of corn stover during the harvest season in the Huang-Huai-Hai region of China is approximately 50%. To achieve rapid off-field transportation and to prolong its shelf life, a method suitable for corn stover with medium-high moisture content was considered based on the stover multistage continuous cold roll forming method. An orthogonal experiment was adopted by taking the moisture content, sterilization method, and inhibitor addition method as experimental factors and taking the shelf life, percent rebound, and density of the molding blocks as the experimental indices. It was found that the steam sterilization method can prolong the shelf life of the molding block the most. The percent rebound and the density were primarily affected by the moisture content, followed by the sterilization method. A comprehensive analysis indicated that the optimal treatment mode was a moisture content of 45%, and the optimal sterilization method was steam sterilization with no inhibitor. In this mode, the molding block can be stored for 72 h without mildew with an average temperature of 32 °C and an average humidity of 48% during the day. The percent rebound was 24.3%, and the density can reach 310 kg/m3 after the completion of rebound.