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Aluminum extrusion die design eight points——Dongming

2015/5/21      view:

1, aluminum dimensions and tolerances

Dimensions and tolerances of aluminum by extrusion dies, extrusion equipment and other relevant factors in the decision process.

 

2. Select the correct tonnage of aluminum extrusion machine

Select the extruder is mainly determined according to the tonnage extrusion ratio. If the extrusion ratio is less than 10, the mechanical properties of low aluminum products; if the extrusion ratio is too high, aluminum products are prone to surface roughness and angular misalignment and other defects. Solid aluminum extrusion ratio is often recommended about 30, hollow aluminum at around 45.

 

3, extrusion mold shape determined 

Extrusion die dimensions refer to the outer diameter of the extrusion die and thickness. Extrusion die dimensions determined by the size, weight and strength of the profile section.

 

4, extrusion mold pore size determination

For a lot of difference in thickness of aluminum, thin-walled portion and forming a hard edge corners area should be appropriately increased size; for generous width larger than the flat wall sections of thin-walled sections and die hole, the beam portion size according to the general profile design, web thickness and size, in addition to considering the factors listed formula, but still need to consider the elastic deformation of the extrusion die and plastic deformation and overall bending from the extrusion cylinder center distance and other factors. In addition, extrusion speed, with or without traction devices also have some impact on the die orifice size.

 

5, reasonable adjustments aluminum metal flow rate

Reasonable adjustments aluminum metal flow rate is to try to ensure that each dot on the aluminum section should die at the same speed out of the hole. Try using porous extrusion die arranged symmetrically designed, according to the shape of aluminum, the differences of each part and the ratio of different thickness and circumference of the extruder barrel from the center of the distance, to design the unequal sizing band. In general, the thinner the thickness of aluminum somewhere, perimeter larger and more complex shapes, the farther away from the center of the extruder barrel, then here sizing band should be shorter. If you set the path to take when using aluminum metal is still difficult to control the flow rate, particularly complex for aluminum sectional shape, thickness is thin, very far from the center portion of the flow angle can be used to promote or lead to accelerated aluminum cone material flow. And for those parts of the wall thickness or the larger the extruder barrel from close to the center of the place, it should be used to supplement impede corner obstacles to slow the flow rate here. Additionally, you can use technology balance holes, process margin or using the front room mold, diversion mode, change the number, size, shape and location of the vent hole to adjust the flow rate of the aluminum metal.

 

6, extrusion die strength check

Aluminum extrusion die due to very bad working conditions, so mold design mold strength is a very important issue. In addition to the rational arrangement of mold hole location, select a suitable mold materials, design reasonable mold structure and appearance outside, to accurately calculate the pressing force and check each dangerous section of the allowable strength is also very important. Formula to calculate the current squeeze a lot of pressure, but after not Erlin revised formula still works value. The pressing force of the upper limit of solution, and has a good practical value, calculated using the empirical coefficient method extrusion pressure is relatively simple. As for the strength of the mold check, it should be based on the type of product, mold structure, respectively. Generally flat mold only needs checking shear strength and flexural strength. Tongue porthole die and you need to check the shear modulus, flexural and compressive strength, tongue and the tip portion also need to consider such as tensile strength. A strength check when important basic problem is to choose the appropriate intensity and more precise theoretical formulas allowable stress. In recent years, the mold can be used for particularly complex finite element method to analyze the situation and check the strength of the force.

 

 7, reasonable working band size

To confirm with porthole die much morecomplex than to determine the mold halves work, not only to take into account the difference in thickness profiles, distance from the center, face and must take into account the situation die hole is diverted bridge obscured. In shunt die hole under the bridge, since the metal flow into difficulties, working with some thinning must be considered. In determining the work zone, we must first find out the wall thickness of the thinnest profiles bypass bridge that is the largest local metal flow resistance, with minimal work here as twice the wall thickness, thick wall or metal easy to reach place, work with due consideration to thick, generally based on a proportional relationship, coupled with the correction value and easy mobility.

 

8, the die orifice air knife structure and size

Die orifice air knife is working with the die orifice outlet end of the boom support structure. When the aluminum wall thickness 2mm, we can use relatively easy to process direct air knife structure; when t <2mm, the cantilever of the process choose to oblique air knife.