Solid shapes extrusion

Abstract

A method of forming a generally L-shaped extrusion from a body of aluminum alloy, the extrusion having good flatness and straightness without the use of a straightening step. The method comprises the steps of providing a body of a precipitation hardenable aluminum alloy and providing an extrusion press having a die for extruding a hollow-shaped tube having a generally rectangular-shaped cross section. The body is extruded to provide the rectangular-shaped tube which is then precipitation hardened to increase its strength. After precipitation hardening, the tube is machined in the longitudinal direction to separate it into two L-shaped members having good flatness and straightness.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. Provisional Application No. 60 / 529,442, filed Dec. 12, 2003, incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] This invention relates to extrusions such as aluminum extrusions and more particularly it relates to a method of extruding to produce extrusions having improved flatness and straightness. [0003] In extruding conventional parts from aluminum there is often great difficulty in producing an extrusion having dimensional stability. For example, if the extrusion has an L-shaped cross section with one leg thinner than the other, i.e., high aspect ratio, then it is necessary to vary the bearing surface of the extrusion depending on the leg. That is, if the L-shaped extrusion has one leg approximately 0.35 inch thick and a second leg 0.050 inch thick, then the die has to be designed to slow down the extrusion speed of the 0.35 inch thick leg to the speed of the 0.050 inch thic...

AI Technical Summary

Benefits of technology

[0016] It is another object of the invention to provide an improved extrusion process which results in flat, straight extrusion members free from twisting.

[0017] It is yet another object of the invention to provide a method for extruding aluminum alloys having L-shaped cross-sectional configurations, for example, which are free from warping and twisting and which can eliminate the straightening process.

[0019] In accordance with these objects, there is provided a method of forming a generally L-shaped extrusion from a body of aluminum alloy, the extrusion having good flatness and straightness without the use of a straightening step. The method comprises the steps of providing a body of a precipitation hardenable aluminum alloy and providing an extrusion press having a die for extruding a hollow-shaped tube having a generally rectangular-shaped cross section. The body is extruded to provide the rectangular-shaped tube which is then precipitation hardened to increase its strength. After precipitation hardening, the tube is machined in the longitudinal direction to separate it into two L-shaped members having good flatness and straightness.

[0020] While the tube has been disclosed and machined to form two L-shaped members, it will be appreciated that the tube may be machined or cut to form U-shaped members. Further, while the body has been extruded to form a tube having a rectangular cross section, other shapes can be extruded such as square, parallelogram, triangular, circular, cross-sectional shapes or even more complex shapes are contemplated. Such other shapes can be machined to provide the desired shaped member having good flatness and straightness. While a rectangular extrusion has been disclosed for machining into L- or U-shaped members, it will be appreciated that the method can be used for forming other shaped members from extrusions.

[0021] Thus, a method is also disclosed for producing a shaped member from a body of aluminum alloy, the member having good flatness and straightness without the use of a straightening step, the method comprises the steps of providing a body of an aluminum alloy and providing an extrusion press having a die for extruding an extrusion having at least one hollow tubular member. The method further comprises extruding the body to provide the extrusion and thermally treating the extrusion to increase its strength. Then, the extrusion is machined in a longitudinal direction to separate it into at least one shaped member having good flatness and straightness.

Problems solved by technology

In extruding conventional parts from aluminum there is often great difficulty in producing an extrusion having dimensional stability.

Slowing extrusion speed translates to a loss in productivity.

In addition to the loss of productivity, the L-shaped extrusion can have dimensional stability problems.

That is, even if the two legs extrude straight, the two sections will have a different extrusion factor which results in problems.

For example, the extrusion factor can create dimensional stability problems after the thermal treatment or during the straightening process.

Thus, the conventional extruding process has problems of dimensional change after the thermal treatments.

These problems include flatness, angularity, straightness and twist of the extrusion.

Further, conventional extruding can result in a large amount of straightening time.

In addition, there can be inconsistent dimensions within the same part resulting from the manual rework required.

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