ã€China Aluminum Industry Network】 (1) When reclaiming, moving, and stretching aluminum alloy profiles, it's essential to avoid rubbing, pulling, overlapping, crowding, or tangling them. They should be placed at appropriate intervals to prevent damage. For profiles that are prone to bending or deformation, timely processing is necessary, and in some cases, protective measures should be taken to prevent mutual damage.
(2) Stretching of aluminum alloy profiles should only be performed after they have cooled down to below 50°C, which allows for safe handling with bare hands. If the temperature is too high, it can lead to deformation and even burns. Additionally, improper stretching at high temperatures may fail to eliminate internal stresses effectively, resulting in issues like bending, twisting, and poor performance, ultimately causing waste products.
(3) Since the top parts have a heat-resistant diffusion effect, aluminum profiles with high decorative finishes should be flipped up and down before and after stretching. This helps ensure even heat dissipation and reduces horizontal bright spot defects caused by uneven cooling and crystallization, especially for large and thick profiles where this issue is more common.
(4) Pay close attention to the tolerances of complex features such as small feet, thin teeth, long legs, curved surfaces, slanted surfaces, openings, and angles on high aspect ratio profiles. These features are more susceptible to dimensional deformation, twisting, or spiral distortion due to uneven force application. Careful handling is required to maintain the integrity of these intricate designs.
(5) The amount of stretching should typically be controlled around 1%. For example, a 25M aluminum alloy profile should be stretched approximately 25 cm after straightening, but it must not exceed 2%. Adjustments should be made based on the specific conditions of the extruded profile, including opening size, surface quality, external dimensions, inner diameter, wall thickness, elongation, and other factors. The goal is to meet conflicting technical requirements while ensuring all specifications are satisfied. Over-stretching can cause head-to-tail size deviations, surface warping (fish-scale patterns), reduced elongation, increased hardness, and brittleness. On the other hand, under-stretching may result in low compressive strength, hardness, and even failure to improve hardness during aging (quenching), leading to easy bending or "large knife bend."
(6) To accurately control tensile deformation and manage dimensional changes across the entire profile, suitable special clamps and effective methods must be used. This is especially important for materials with open sections, curved shapes, cantilevered structures, and irregular forms. It’s crucial to use the stretching pads properly and, if needed, install a centering or plug pad in the middle of the stretched profile to ensure the length between the head and mid-section meets the required standards for the aluminum alloy profile.
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