Claims
- 1. A die apparatus for forming a high strength metal article under elevated temperature and pressure, comprising:
at least two opposing die segments together forming a hollow mold chamber for receiving a mold blank between the die segments, the mold chamber having a longitudinal axis and a radial central plane transverse to the longitudinal axis; each die segment having an inner surface having a plurality of spaced, elongate formations extending in a direction non-parallel to the longitudinal axis, each formation having a first side facing the central plane and a second side facing away from the central plane; and at least the majority of the formations comprising non-uniform formations having a first and second side at a different angle relative to the central plane, the angle of the second side being greater than the angle of the first side.
- 2. The apparatus as claimed in claim 1, wherein the formations comprise ribs.
- 3. The apparatus as claimed in claim 1, wherein the formations comprise indents.
- 4. The apparatus as claimed in claim 1, including at least one uniform formation located at least approximately at the radial central plane.
- 5. The apparatus as claimed in claim 1, including additional formations extending parallel to the longitudinal axis, the additional formations being of uniform shape.
- 6. The apparatus as claimed in claim 1, wherein the formations extend substantially transverse to the longitudinal axis of the mold chamber.
- 7. The apparatus as claimed in claim 1, wherein the angle of the second side of each non-uniform formation is predetermined as a function of distance from the radial central plane, the non-uniform formations having second side angles which increase with distance of the respective formation from the radial central plane.
- 8. The apparatus as claimed in claim 7, wherein a plurality of non-uniform formations are located at spaced intervals on opposite sides of the radial central plane, and the progressions of the slopes of the second sides of the formations in opposite directions from the radial central plane are mirror images of each other.
- 9. The apparatus as claimed in claim 1, wherein the first side of each formation is substantially parallel to the radial central plane.
- 10. The apparatus as claimed in claim 1, wherein the formations extend in substantially helical paths around said mold chamber.
- 11. The apparatus as claimed in claim 1, wherein the formations extend in substantially circumferential paths around said mold chamber.
- 12. The apparatus as claimed in claim 1, wherein the formations are generally triangular in shape.
- 13. The apparatus as claimed in claim 1, wherein the formations are generally rectangular in shape.
- 14. A method for molding high strength metals under elevated pressure and temperature, comprising the steps of:
providing a mold blank comprising first and second planar metal sheets of the same size periphery, aligned in a co-planar orientation, and having a continuous weld bead along the periphery of the metal sheets, with a gas fitting at a position between the first and second sheets for gas injection into the mold blank; providing an openable mold comprising at least two opposed dies having interior surfaces forming a hollow mold chamber for receiving and molding the blank, the mold chamber having a radial central plane, each die having at least one set of elongate formations on its inner surface for forming stiffener ribs on a molded part, each formation which is not located at the central plane having a first side facing said plane and a second side facing away from said plane, at least the second side being slanted towards the central plane of the chamber; inserting the mold blank between the opposed dies with the gas fitting projecting outside the dies, and closing the dies to contain the blank within the mold chamber; heating the mold and contained blank to an operational molding temperature; pumping pressurized gas into the interior of the heated blank and expanding the blank outwardly to conform to the shape of the interior surfaces of the opposed dies, with portions of the blank contacting and being formed around the formations so as to form corresponding ribs in the sheets forming the blank; allowing the mold and molded blank to cool, relieving gas pressure; and removing the resultant metal article from the mold.
- 15. The method as claimed in claim 14, wherein the formations comprise ribs.
- 16. The method as claimed in claim 15, wherein the amount of slant of each non-central rib is dependent on the distance of the rib from the central radial plane and increases with distance from said central radial plane, the slant being such that, as the molded metal cools and contracts, the force resulting from the contracting metal portion against the second side of each rib is not directed transversely into the rib.
- 17. The method as claimed in claim 15, wherein the first sides of the ribs are oriented approximately parallel to the central radial plane.
- 18. The method as claimed in claim 14, wherein the mold blank is of titanium or titanium alloy.
- 19. A die apparatus for forming a high strength metal article under elevated temperature and pressure, comprising:
at least two opposing die segments together forming a hollow mold chamber for receiving a mold blank between the die segments, the mold chamber having a center and a radial central plane extending through the center of the mold chamber; each die segment having an inner surface having a plurality of elongate formations of generally triangle-shaped cross section projecting inwardly into the interior of the mold chamber; and at least the majority of the formations being of non-uniform, non-isosceles triangle shape.
- 20. The apparatus as claimed in claim 19, wherein each non-uniform formation is spaced from said radial central plane, a first set of formations being located at spaced intervals between said central plane and one end of the chamber, and a second set of formations being located at spaced intervals between the central plane and opposite end of the chamber, each non-uniform formation having a first side facing said central plane and a second side facing away from said central plane, and said first and second sides being at different angles relative to said central plane, the second sides being at a larger angle to said central plane than said first sides.
- 21. The apparatus as claimed in claim 20, wherein the angles of the second sides of said formations in each set increase with distance from said central plane, the two sets of formations being mirror images of each other.
- 22. The apparatus as claimed in claim 21, wherein the second sides of said formations in each set are each at a predetermined angle such that said second sides are directed generally towards the center of said mold chamber.
- 23. The apparatus as claimed in claim 19, including at least one formation located substantially at said central plane, said one formation being of uniform isosceles triangle shape.
- 24. The apparatus as claimed in claim 19, wherein the mold chamber has a longitudinal axis and the radial central plane is transverse to the longitudinal axis, the non-uniform formations extending in a direction which is not parallel to the longitudinal axis.
- 25. The apparatus as claimed in claim 19, wherein the elongate formations comprise ribs.
- 26. The apparatus as claimed in claim 19, wherein the elongate formations comprise indents.
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority of U.S. provisional application Serial No. 60/378,768, filed May 7, 2002, which is incorporated herein by reference in its entirety.
Provisional Applications (1)
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Number |
Date |
Country |
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60378768 |
May 2002 |
US |