[China Aluminum Network] Common single-finger round (shaped) aluminum alloy pipe up and down bias value. The reason for the ellipticity of round (shaped) tube is mainly aluminum extrusion die manufacturing, but there is little relationship with aluminum extrusion die design.
cause:
(A): artificial milling, digging, planing, cutting aluminum extrusion mold for the feed chamber, welding room, mold core size, shape processing asymmetry, resulting in inconsistent finish, which is the main reason, many mold factory at any cost With the introduction of a machining center, computer-controlled automatic processing programs are a guarantee for the dimensional accuracy of symmetrical molds (including round tubes). Eliminate the large size deviation of man-made processing, and the factors of uneven flow velocity!
(II): The ratio of the wall thickness of the aluminum alloy pipe to the length of the working belt is not correct (about 1:2.5). The proportion of oversized and small increases the flow velocity and friction factors, which affects the aluminum flow rate in the aluminum extrusion die working belt. Increased uncertainties and caused speed.
(C): Aluminum profile mold strength, mold core strength, the size of the upper mold empty knife, with smoothness of bridge hole can affect.
(d): Aluminum extrusion speed is too fast or too much traction, the amount of stretch is too large.
Elimination method:
(A): The production of qualified and excellent quality aluminum extrusion die is fundamental!
(B): The control speed of aluminum extrusion production is the main, otherwise the surface is also very easy to rough, this is because the front air knife of the round tube is generally not large (0.5mm), easy to stick Mg2Si particles. In order to obtain the surface quality, the work belt is short and the material is smooth but not pressure resistant. After the new mold is nitrided, 40 to 50 rods are generally produced and then nitrided again.
(C): When producing double-hole, porous thin-walled aluminum alloy pipes, more attention should be paid to the influence of traction on the outside diameter of the profile and the ellipticity of the aluminum profiles. Due to the relationship between material discharge speed and traction, traction tends to be concentrated on the slower one. .
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