Several Mold Repair Methods for Hollow Aluminum Extrusion Dies
ã€China Aluminum Industry Network】 Aluminum profile extrusion die is an important tool in the aluminum extrusion process. It is the basic tool to ensure the product has a correct shape, size and accuracy. In actual production, we will give corresponding repair methods for several problems that may occur in the extrusion of hollow aluminum profiles.
First, there is a seam angle or poor welding hollow aluminum alloy extrusion using a flat-flow split mold extrusion, metal flow through the process of welding, welding, so the hollow profile is the existence of welding line, if the metal welding is not good gaps, then It is a defect.
There are two reasons for gaps. One is that the split hole, narrow welding room, insufficient metal flow, the metal does not form enough hydrostatic pressure in the welding chamber, the product does not weld well out of the die hole, resulting in the existence of welded products Gap; Second, over-lubrication and poor lubrication lead to poor welding of hollow sections. The former can be used grinding or milling to expand the area of ​​the shunt hole and the welding chamber, increase the metal supply flow, so that the metal can form a sufficient hydrostatic pressure in the welding chamber to solve, the latter can be used without lubrication extrusion process.
Second, the aluminum alloy profile wall concave or convex convex surface 1, hollow aluminum alloy profile wall concave concave surface causes: mold core work belt is lower than the lower mold hole work belt, mold core working band effective length Caused by short.
Correction method: Place a spacer between the core and the lower mold to make the core work belt sizing with the lower mold hole in the stressed state. At the same time, reduce the same thickness at the exit of the lower die.
2. Causes of hollowed out aluminum alloy profile wall: The mold is used for a long time, the core work is heavily worn, grooves appear, and the frictional resistance is increased. The slow flow of the metal causes the convexity of the hollow profile wall.
Correction method: If the profile wall thickness tolerance allows, you can repair or grind the surface of the work belt of the mold core to reduce the frictional resistance; if the wear of the mold core working tape is very serious, and the profile wall thickness has reached the upper deviation, the mold can be Preheat to about 300 °C, make up the welding core shape, then repair it to the required size and use it after polishing; if the core work belt is not worn out, then take a side to the outer side of the mold core working area and the inside of the detention area You can.
Third, the appearance of streaks on the outer surface of the surface of the aluminum alloy profile stripe extrusion profile, after anodizing is more obvious. This defect is more common in parts where the wall thickness of the profile is large, where the metal is welded under the shunt bridge, and where the back is located on the inside with the “twig†and the threaded hole.
cause:
1. "Structures" and tapped holes on the inside of the profile cause surface streaks due to insufficient or excessive metal flow;
2. Stripe surface profile caused by the weld zone under the die-distribution bridge;
3, the profile section design problems, due to the profile of the wall thickness difference, the work of the sudden change in the length of the site after the anodized stripe-like color;
4, due to lack of cooling capacity of the machine, resulting in anodized black markings;
5. The texture of the slab itself is not good, which affects the stripe color difference after the anodization of the extruded material.
Correction method:
1. Check if there are any differences such as large wall thickness of the profiles, branches and threaded holes on the profile of the customer's drawings.
2. The diverting bridge should be designed on the non-decorative surface of the profile. While guaranteeing the strength of the mold, the welding chamber should be as large as possible so that the metal can form enough hydrostatic pressure;
3, large-diameter pipe or large hollow profile mold, in the male mold can be equipped with upper welding room;
4. The “twig†or threaded hole striations on the inside of the profile. The method of repairing the die is polishing the die hole work zone of these parts, smooth and smooth, or modify or reduce the connection transition radius of these parts;
5, sometimes the stripe is formed by the billet material itself, requiring uniform heating temperature of the billet, uniform annealing thorough;
6. After the extrusion material exits the die hole, its grain size depends on the temperature entering the quench zone and the cooling rate in the quench zone. If the cooling temperature is too low and the cooling rate is not uniform, the grain size will be too large or the grain size will be uneven. After the anodization, the color difference will be more obvious. The operator is required to adjust the wind pressure and cooling water pressure of the cooling system in time.
Fourth, aluminum alloy bending and twisting causes:
1. The work belt of the core and the lower die hole is unreasonable, causing uneven metal flow velocity in various parts of the profile.
2. The size and position of the orifices of the symmetrical hollow profile die are asymmetrically processed, and the metal supply flow is not balanced, resulting in uneven metal flow rate;
3, the processing of the orifice is irregular or there are obstructions on the core to hinder the metal flow.
Correction method:
1. Use a suitable method to grind the outlet of the mold core or the split hole, and if necessary, appropriately expand these split holes to balance the feed.
2. Remove the obstruction with a sanding method.
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