Aluminum profile: optimal cross-section
How to make the aluminum profiles
Refers to extruded aluminum profiles. These aluminum profiles manufactured by hot extrusion An important part of this process is the extrusion die. The simplest form of a matrix - a steel disc with a hole, the contour of which coincides with the cross section of the profile (figure 1).
Fig. 1 – Extrusion of an aluminium bar [1]
The extrusion process itself is relatively simple.. the contour of which coincides with the cross section of the profile (figure 400 to 550 °C (depending on the alloy) is loaded into a heated container. When the press ram moves inside the container, a huge pressure arises and the material begins to flow through the hole of the matrix and exit it already in the form of a profile with a cross section, which is given by the matrix hole. For the extrusion of hollow profiles, dies with a much more complex design are used., than just a steel disc with a hole, especially for profiles with multiple cavities.
Pressing tool
Extrusion matrix not only form a cross-sectional profile. It is also a carrier, which must withstand the full pressing force and through the auxiliary pressing tool (pads, which must withstand the full pressing force and through the auxiliary pressing tool (pads.
Working conditions of the extrusion die
these loads, according to the press, can reach 10000 tonnes, and the pressure on the mirror matrix – 880 MPa [2]. Therefore, the matrix is made of high-strength, heat-resistant tool steels. The stresses in the matrix increase with its size (diameter) and complexity.. When the large matrix is used for compression of high aluminum alloys, The stresses in the matrix increase with its size (diameter) and complexity..
Modern matrix for multi-cavity profiles are a complex combination of mandrels, forming the inner contours, and the feed channels, which is fed under high pressure metal. Between these functional elements should be enough space to accommodate the load-bearing elements of the necessary strength and rigidity. The lack of load-bearing capacity leads to early failure of the matrix, and lack of rigidity - to excessive elastic deformation of the matrix and, Consequently, large deviations from the specified dimensions of the cross-sectional profile and shape of the profile – longitudinal deflection, waviness, torsion.
Profile for good extrusion
The size and shape of the cross-sectional profile can strongly influence, as the ability of the matrix to achieve the commanded pressing accuracy, and the reliability and durability of the matrix. Simple design rules of cross-sections of aluminum profiles, apparently, does not exist.
Below are some practical guidelines for designing profiles with specific "bad" and "good" examples of cross sections (Fig.. 2). According to these recommendations can be judged, why the profiles with one cross-section of a press easily, in others it is very difficult. Some of the recommendations may relate more to the profiles with a large cross-section, than to the profiles with a small cross-section.
The figure 3 shows the classification of aluminum profiles according to the degree of complexity of extrusion.
Fig. 2 – Examples for basic empiric design rules for extruded sections [1]
Fig. 3 – The sections are classified according to the difficulty to produce extrusions [2]
- Design of Aluminium structures: Selection of Structural Alloys /R. grid // EUROCODES – Background and Applications – 2008
- Aluminum Extrusion Technology / P. Saha
