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Exploring Profile Stretch Forming (1): Techniques and Applications in Aluminum Profile Bending

Limitations of Stretch Forming: Understanding Its Constraints and Considerations
With lightweighting becoming one of the important development directions in high-end equipment manufacturing technologies such as automotive, aerospace, and high-speed trains, profile products have gained increasing application due to their advantages of lightweight and high strength. In multiple application fields, as the design level improves, the auxiliary design methods become more advanced, and the functional and aesthetic demands of related products increase, the structures of most profile products are trending towards complex streamlined designs. Traditional two-dimensional bending processes are no longer able to meet the forming requirements, making precise three-dimensional bending plastic forming methods a hot topic in the field of metal material processing.
Due to the complexity and difficulty in controlling the shape of profile three-dimensional bending forming, based on the current status of profile bending forming, numerous scholars and researchers have studied the laws of springback deformation of formed components and optimized bending process parameters, aiming to provide references and new methods for profile bending processes.
In this series of articles, we summarize the research status of profile bending processes and discuss the urgent technological breakthroughs needed for profile three-dimensional bending forming, providing valuable references for research in the field of profile three-dimensional bending.

Three-dimensional stretch forming

Three-dimensional stretch forming is one of the most widely used processes in the bending and forming of aluminum profiles. It relies on the three-dimensional movement of the clamp and the bending die to bend the profile into a predetermined shape. Compared with bending forming, the profile deforms while bending , each point on the section is under the action of axial tensile stress, which avoids the wrinkling phenomenon caused by tangential stress, and can reduce the springback, thereby improving the quality and precision of the profile stretch bending.

Stretch Forming Process of Aluminum Alloy Automobile Roof Rack【Stretch Forming Machine

The stretch forming process is generally divided into three steps: pre-stretching, stretching and supplementary stretching. Pre-stretching is to pre-stretch the profile to a plastic state through the clamps at both ends of the profile; the stretching stage refers to controlling the three-dimensional movement of the clamps. Make the profile fit the mold gradually until the profile is in full contact with the mold; Supplementary stretching means to continue to apply additional supplementary tension to the profile after the mold is closed, and its main purpose is to reduce springback.

Three Different Stretch Forming Processes

With the continuous development of stretch forming technology, based on the basic principle of stretch forming, a variety of different stretch forming processes such as stretch arm stretch forming and rotary table stretch forming have been derived.

Tensile Stretch Forming

The mold is fixed, and the rotating arms on both sides drive the clamps to translate and rotate under the drive of multiple hydraulic cylinders or motors, so as to produce a stretching effect on the profile, so that the profile is gradually attached to the stretch forming mold. Since the two sides can be controlled The side arm moves independently in a large range, so this stretch-arm stretch forming method is suitable for three-dimensional stretch formingof large geometric dimensions, complex shapes, and asymmetrical profiles [5]. When using stretch-arm stretch bending, the clamp can also be fixed , Control the movement of the stretch formingdie to make the profile and the mold close to each other. This method is difficult to achieve complex shapes of profiles, and is mainly used in two-dimensional stretch bending.

Rotary Table Stretch Forming

This process method was first used in aircraft manufacturing. This stretch forming method is to drive the stretch forming mold to rotate through the rotation of the turntable, so that the profile is gradually clamped with the mold under the action of axial tension. This process method is suitable for small-sized profiles The processing of products has the characteristics of high forming efficiency and high precision[5]. They are respectively installed on two different turntables. With the movement of the double turntables, the clamps and molds move relatively at the same time to complete the bending and forming of the profile. In this way, since the clamps and molds both follow the turntables, the processing time is shorter. Shorter, and the accuracy is further improved, it is mainly used in mass production of auto parts.

Flexible Stretch Forming

Generally, it can be divided into two types. One is the stretch forming with flexible loading, which can be regarded as the deformation improvement of the stretch arm stretch forming machine. Workbench, through the movement of the workbench to adjust the processing range of profile products, has a certain degree of flexibility; the other is multi-point flexible mold stretch bending, and its forming mold is composed of multiple discrete parts, making the mold flexible and adjustable, which can be Transform into any shape, and then meet the various requirements of the processed parts.


Achieving Perfection: The Quality Finish Advantages of Stretch Forming
Achieving Perfection: The Quality Finish Advantages of Stretch Forming

Profile stretch forming is a versatile technique used in the bending and forming of aluminum profiles. With the ability to shape complex three-dimensional profiles, reduce springback, and enhance precision, it finds application in various industries. The different stretch forming processes, including tensile stretch forming, rotary table stretch forming, and flexible stretch forming, offer unique advantages and are suitable for different profile bending requirements. By leveraging the capabilities of profile stretch forming, manufacturers can achieve precise and high-quality results in the production of profiles for diverse applications.