At the end of the pressing cycle press for the extrusion of aluminum - extrusion press - typically always press-formed residue - residue preform, which is removed from the press in the waste. See. more Baling press with aluminum-residue.
The thickness of the discard
The thickness of the discard usually prescribe one of those reasons, so that it is separated from the metal in the matrix as easily as possible, It does not damage the remainder of the matrix metal is removed from the press and. However, we know, that the surface layer preform - the surface of the aluminum ingot – It contains a significant amount of pollution, including, various oxides of the alloying elements of the alloy. At the end of the pressing cycle, these surface impurities accumulate at the end of the workpiece and begin to flow within the molded profile.
This process begins when the length of the discard about 15 % of the original length of the workpiece - much more than a press residue, which is removed in most extrusion presses. However, considered, These inclusions are usually completely fall into the aluminum profile and therefore do not affect the quality of its surface. Except in cases, when etched profiles, for example, when anodizing. The scheme for calculating the thickness of the discard is shown below.
Press the rest of alloys 6060-6063 and 6061-6082
Of course, You can worry about the influence of such inclusions on the mechanical properties of the structural profiles aluminum alloys 6061 and 6082, which should provide increased strength, since they are often used for load-bearing structures. In this case, commonly used press residue thickness just 15-16 % of the original blank length.
Therefore, two different situations arise:
- Compression profiles from non-structural aluminum alloys 6060/6063 with as short as possible removable press-residue.
- Compression-type structural alloys 6061 and 6082 with the remainder of the press at least 15-16 % the length of the workpiece to avoid defects from entering the surface layers of the preform inside profile.
The separation of the discard
aluminum alloy type of impact on the optimal design of the blade release mechanism of the discard. The blade is in the form of a scoop or spoon is used more often for most aluminum alloys 6xxx series. However, the optimum blade design also influences the thickness of the discard, which, in turn, It depends on alloy. Some plants use very thick press leftovers for responsible products of alloy 6061, for example, for the automotive industry. In such cases, the firm Castool, for example, recommends its design Delta.
Press the remainder of 1xxx and 3xxx alloys
Separation of press remnants of a really soft alloys 1xxx and 3xxx has its own characteristics. For these alloys are characterized by high metal adhesion to the blade. Therefore, the blade is used in the form of a scoop-spoon for their edges with a special shape.
Currently, there is a tendency to work with very short press remains. This is due to the fact, which are increasingly used high-quality aluminum ingot-columns with a minimum thickness oxide rich surface layer. Therefore, the rest of the press naturally folds under the influence of a knife with a conventional blade. There is not even necessary to use special radius of the blade for better folding press residue.
Press the rest of alloys 2xxx and 7xxx
solid series aluminum alloys, 2xxx and 7xxx require thick press residues - usually about 15 % the length of the workpiece. Since these press residues never wrap, they just need to be separated from the matrix metal. In this case, do not use sharp blades, a special blade for better metal shear.
However, not all 7xxx alloys fall into this category. Most soft alloys of the 7xxx series, such as 7003, 7005, 7020, fall into the same group, that hard alloys 6xxx series, such as 6061 when the thickness of the discard is often even thinner, than an alloy 6061.
A source: www.castool.com