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Cold forming of new technology development and application

First, the finite element analysis and computer simulation
    Computer simulation of cold forming and finite element analysis is a focus of theoretical research, has published research papers and more. How for the production of practical problems, the computer simulation, to solve specific problems, should be the objective of the study and test results basis. We are based on the actual problem, made a double zero within the radius of the hem, wide board bag-shaped wave defect analysis, pre-punched hole shape distortion in the simulation, and conducted related experiments.

    1. Double-fold within the simulation of zero radius

    Cold forming components, the double fold is a common form. Double fold design, the address width of the calculation and determination of reasonable step molding process is the key issue. Done using MSC Marc FEM conclusion is as follows:

    (1) through the deformation zone of the equivalent strain analysis is verified in the deformation process, with further bending sheet metal, which layer of the layer off-center, moving inside to the bend. Simulation shows that the specific migration processes and values.

    (2) the comparison of the unit before and after deformation was found bent in peripheral cell contraction, occurs within weeks of cell elongation, bend the middle of the plate thickness increases, material flow occurred.

    (3) the analysis of stress and strain and found that bending deformation and plane strain cross section close to the characteristics, which determine the bending of sheet metal can be reduced to plane strain problem.

    (4) through the analysis of bending stress concentration, to confirm the peripheral concentration of greater tensile stress, bending stress to the high concentration of regional and non-bend in the bending area (or smaller bending region) of the transition zone have large shear stress concentration.

    2. Wide Defects in Sheet Metal Forming

    Bag-shaped wave is generated wide plate forming a common problem. In the compartment plate, pressure plate, wide roller shutter door profiles often occur during cold bags of wave-shaped defects.

    Experiment according to different thickness and the roll configuration 18 combinations of the experiment, and bags for the more obvious form of waves, edge waves, longitudinal bending from the mechanism of the three defects, the experimental results and other aspects of the analysis, proposed the elimination of defects and corresponding measures. The main conclusions are as follows:

    (1) bag-shaped wave generation was mainly due to plate bending process in the emergence of the phenomenon of off-line, produced in the curved part of the transverse tensile stress and transverse strain. According to the Poisson deformation of sheet metal between the longitudinal shrinkage occurs, and the longitudinal contraction is not part of the central part of contraction exerted pressure on the middle part of the sheet-shaped wave instability appears bags. Bag-shaped wave is mainly elastic deformation.

    (2) appears bags may be appropriate to add some form of waves pass. The width of the edge section of the bags have a certain influence wave shape, thin bags are more likely than the plate-shaped wave. Can be done by force to slow the sheet Shijia La Bag-shaped wave.

    (3) side effects of wave generation are two comprehensive, the first generation with the same wave-shaped bags, the second section of the edge part of the material is first cut in the external force is stretched longer, and then again plastic deformation is caused by compression and shear edge waves. Superposition of these two results with each other, resulting in edge waves. The pass edge waves are likely to occur in front of the pass there on the edge of the wave is relatively large. More vulnerable than the thick plate side of the waves, broad-brimmed more prone than the narrow edge of the waves.

    3. Pre-punched hole shape distortion of the Simulation

    The direction of cold forming is one of product development and continuously meet the needs of a variety of applications, to achieve a variety of functions in the product. Cabinet column profiles, the shelf profile and so needs to be completed by pre-forming punch. The pitch and demanding hole geometry, does not allow large bending deformation generated in the process, so pre-punched hole shape distortion of simulation and control measures is very important.

    To pre-punching of sheet metal as an example, field experiments were controlled by pre-punching of sheet metal cold forming process hole shape distortion of the new method of analysis of the mechanism of hole shape distortion, and the results are summarized. At the same time using computer simulation software to simulate the process and results of field experiments and computer simulation results were compared.

    According to the process diagram, the simulation results and the curve with the cloud and the material displayed in the cross section deformation, in order to further understand the process of deformation of the rolling basis.

    Die by the different simulation results comparing the effect of different pre-punching die area of ​​the material impact of stress and strain, has been the best experimental model for the program.

    Processed through the cross-section of sheet metal stress and strain analysis of the situation have found the main hole shape distortion defects: sheet metal hole shape distortion produced is due to: the material punching edge region in the molding process there will be great stress increment, punching area equivalent stress increased gradually in the process, the strain also will be accumulated. Pre-punching part of forming the lateral angle of the transverse displacement of the plate. Manifested in the pre-punched on the edge of the displacement produced a larger strain, and then had a hole-shaped distortion, when the degree of strain accumulation over the material strength limit, tearing the situation occurs.

    The optimal simulation scheme based on, modify the roll artwork, and conducted field experiments. Experimental results show that simulation results can be used as the basis for mold design, and very effective to avoid the generation of hole-shaped distortion.

    Second, high precision and complex line profiles

    Cold forming is especially suitable for mass production. Relative to the bending process, cold roll forming production efficiency, product size consistency, and can not produce the complex bending truncate. With the rapid development of China's car industry, high precision and complex line profiles of the cold forming more and more demands.

    Doors and windows on the car parts, cold forming is often the first procedure and key processes. After cold forming metal layers also need to point in some interval of seam welding. So the production line also needs to include online seam welding equipment, cutting equipment tracking.

    Car doors and windows for cold forming production line, not only pass multi-shaping and high precision. We summarize and test mill proposed for controlling the accuracy of a dozen indicators, the focus is to control the axial movement of the mill and all the units in the axial location on the basis of accuracy.

    Rational development of molding techniques, and by using the simulation software COPRA to determine the optimal molding step. Using CAD / CAM technology to produce high-precision roller, smooth rolling out a number of high-precision complex profile.

    COPRA of Germany data M's software is specialized software designed for cold forming, the most widely in the international application, the domestic industry's leading companies have adopted it as a means of developing new products. We apply this software has been successfully designed and manufactured hundreds of cold formed products.

    Third, the cold-formed profiles online bend

    Many profiles require a 2-D on the length of arc, bending line after forming section is a better way. Over the past commonly used method is adopted in the press bending mold, mold need to go through repeated testing, when the nature of the material change, the need to frequently modify the mold. Press bending requires a specific tooling installation of a part within the core, to avoid bending folds produced during the defects. After the completion of the removal of these inner core, heavy workload, low efficiency, poor security.

    Online only need to bend at the exit of cold-formed profiles online bend round to install a device to enable profiles to meet the requirements of the arc size. The device can be adjusted to address different material properties and material rebound impact. As long as the 2-D arc, whether it is in the horizontal plane or in the vertical plane, can be bent to achieve online.

    In theory, a 3-point arc to determine. But to get a better bending quality, through testing we believe should be given shape deformation trajectory track curves to determine.

    Bending deformation curve of a particular track by equation: ρ = ρ0 + αθ

    Or by the equation:

    x = a (cosΦ + ΦsinΦ)
    y = a (sinΦ-ΦcosΦ)
OK.

    Fourth, CAD / CAM integration technology to produce high-precision roller

    To our many years of accumulated research results into productive forces, for domestic and foreign customers to provide high quality technical service and technical support, set up in Shanghai Le Fu Ming (RlollForming) Machinery Co., Ltd.. Using CAD / CAM integration technology for domestic and foreign customers with a full range of services. Lok Fu Ming multiple existing CNC machine tools and a full set of processing equipment, to successfully provide users with a variety of specifications and on-line high-precision bending roll round, and other related equipment.

    Shanghai's industrial base and rely on the advantages of the Yangtze River Delta, extensive domestic and international cooperation, gathering and cultivating high-quality, high water for the people, coupled with modern scientific management in order to provide customers with quality products and technical services. Lok Fu Ming as an objective, cold forming industry with our common development and progress.

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