There are many problems in the process of drawing and bending aluminum profiles. These problems will seriously affect the product qualification rate and production efficiency and then increase the production cost, which will greatly impact the normal operation and production of enterprises.
Given the need for industrialization of aluminum profile drawing and bending, combined with the current situation of aluminum profile drawing and bending, this paper analyzes the common problems of aluminum profile drawing and bending profile forming and proposes relevant improvement measures, hoping to provide a useful reference for aluminum profile drawing and bending.
Profile profile deviation
Contour degree refers to the profile after drawing and bending, the profile contour after the change, and the degree of conformity of the profile sample or inspection mold tire. The main factors that make the profile deviation are： 1. curvature rebound change of the drawing and bending die; 2. hazardous material of each batch of metallurgical extrusion profile, uneven hardness of local area of each material; 3.excessive change of bending radius of curvature; 4. uneven cross-sectional area of the profile blank.
Surface defects include cracks, shrinkage wrinkles, bending surface depressions, and lateral droop marks after profile bending.
Twisting after drawing and bending
The reason for twisting after drawing and bending is that the cross-sectional area of the profile is not symmetrical, and the stress between the closing edge and the release edge of the profile is not balanced.
The verticality exceeds the difference
Perpendicularity refers to the angular deviation between the vertical reference (perpendicular to the radius of curvature of the mold) and the inspection platform of the cross-sectional area of the profile after bending.
Profile process length
Profile drawing and bending process length refer to the actual length of the part beyond the drawing and bending mold, fixture, and equipment required for the length of the process material.
Safety is the most important issue of concern in the industrial production process. When the profile is drawn and bent, it may suddenly break and pop open outward due to accidental factors, causing damage to equipment and casualties, which in turn will seriously impact the enterprise’s development.
Adjust the curvature of the molding profile
According to the theoretical analysis to calculate the amount of rebound through the tensile test to come up with a correction approximation to amend the mold, as far as possible, so that the profile profile profile after stretching and profile sample or inspection mold tire match, taking into account the instability of the profile, according to the need for later correction, can be pulled over a little.
As the bending radius of curvature changes too much will cause a certain deviation, so the cylinder can be increased in the front of the mold, vertical mold direction, so that the need to bend the profile and the mold coincide, and the drawing and bending mold and the drawn profile should not have a gap. This method can solve the curvature center heterogeneous side of the drawing bending.
In the design process, the form of the profile cross-sectional area and the thickness of each part should be considered. For the asymmetry of the cross-sectional area of the profile, the deviation caused by the imbalance of the stress between the closing and releasing sides of the profile can be appropriately increased in the pre-stretching of the tensile force.
Surface defects treatment
The large tensile force and the unbalanced stress on the edge cause cracks in the profile after drawing and bending. If the edge of the profile is not in place, it will cause shrinkage and wrinkling, commonly known as having a mullet edge. This can be solved by improving the cross-sectional area of the profile or adjusting the tensile force.
Bending surface depression mainly occurs in the cavity profile. This type of profile needs to be filled with a filler to fill the cavity bending part before drawing and bending. Open cavities can be filled with spring steel plates or Teflon fillers, while closed cavities are usually filled with sand, etc.
According to the part where the side droop marks are produced, the mold gap is properly adjusted, and the improvement of the mold material can effectively prevent the profile from being scratched.
Twisting treatment after drawing and bending
After drawing and bending, the main reason for twisting is the asymmetry of the cross-sectional area and the imbalance of stress between the closing and releasing edges of the profile. Given this, industrial aluminum profiles can take the way of increasing the profile pulling force to improve this problem, that is, adding a vertical pushing top cylinder in front of the drawing and bending the die; meanwhile, after drawing and bending, it will be better to keep pressure for some time. In addition, the trace deformation caused by the unstable extruded profile must be completed by later correction.
Verticality exceeds the difference in treatment
After drawing and bending, the verticality exceeding the difference is also caused by the cross-sectional area’s asymmetry and the profile’s uneven street closing and releasing stress. This situation can be improved by adjusting the curvature change of the drawing and bending tool. According to the need for post-correction, it can be pulled over a little, and the trace deformation caused by the instability of the extruded profile needs to be completed by post-correction.
The determination of the profile process length
The rough length of the drawn bending profile is composed of the part length, the die curvature extension (part length, extension, die end rounding together called the effective length of the die), the equipment chuck clamping part, and the equipment chuck extended die rotation gap. In addition to the part length, its collectively referred to as the process length. The mass production process length directly determines the cost of the part. Therefore, it is recommended to meet the bending parts forming state people as much as possible to reduce the effective length of the mold; if necessary, you can open notches at the rear of the mold ends so that the working machine chuck can freely enter the rear of the mold, thereby reducing the process margin at both ends of the wool.
Safety is the primary concern in the industrial production process. Therefore, during the production process, additional guards should be added in front of the profile operating table, corresponding regulations should be formulated, and comprehensive technical operators should be trained. In addition, it is strictly forbidden for operators to stand at the front of the equipment during the profile drawing process.
In summary, the profile to be drawn and bent should calculate each cross-sectional part’s extension force when designing the profile’s cross-sectional area. In the design of drawing and bending tooling, industrial aluminum profiles should consider the curvature rebound changes and pre-deformation of the later correction to reduce the workload of the correction process as much as possible. Safe production is the primary concern of production cost reduction in batch production to reduce the workload of the correction process and reduce the process length of the drawing and bending material. When the extruded profile is unstable, there will be a small amount of bending profile corridor deviation; the twist degree exceeds the poor, the vertical degree exceeds the poor, and other defects can be corrected later to remedy.