Die apparatus and method for high temperature forming of metal products

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;

at least the majority of the formations comprising non-uniform formations in which said first side and said second side are at different angles relative to the central plane, the angle of the second side being greater than the angle of the first side; and

the formations including at least one uniform formation located at least approximately at the radial central plane.

2. 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 in which said first side and said second side are at different angles relative to the central plane, the angle of the second side being greater than the angle of the first side; and

additional formations extending parallel to the longitudinal axis, the additional formations being of uniform shape.

3. 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 in which said first side and said second side are at different angles relative to the central plane, the angle of the second side being greater than the angle of the first side; and

the angle of the second side of each non-uniform formation being 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.

4. The apparatus as claimed in claim 3 , wherein the formations comprise ribs.

5. The apparatus as claimed in claim 3 , wherein the formations comprise indents.

6. The apparatus as claimed in claim 3 , wherein the formations extend substantially transverse to the longitudinal axis of the mold chamber.

7. The apparatus as claimed in claim 3 , 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.

8. The apparatus as claimed in claim 3 , wherein the first side of each formation is substantially parallel to the radial central plane.

9. The apparatus as claimed in claim 3 , wherein the formations extend in substantially helical paths around said mold chamber.

10. The apparatus as claimed in claim 3 , wherein the formations extend in substantially circumferential paths around said mold chamber.

11. The apparatus as claimed in claim 3 , wherein formations are generally triangular in shape.

12. The apparatus as claimed in claim 3 , wherein the formations are generally rectangular in shape.

13. 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 facing into the interior of the mold chamber, and

at least the majority of the formations being of non-uniform, non-isosceles triangle shape;

each non-uniform formation being 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; and

the angles of the second sides of said formations in each set increasing with distance from said central plane, the two sets of formations being mirror images of each other.

14. The apparatus as claimed in claim 13 , 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.

15. The apparatus as claimed in claim 13 , 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.

16. The apparatus as claimed in claim 13 , wherein the elongate formations comprise ribs.

17. The apparatus as claimed in claim 13 , wherein the elongate formations comprise indents.

18. 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 facing into the interior of the mold at least the majority of the formations being of non-uniform, non-isosceles triangle shape; and

at least one formation located substantially at said central plane, said one formation being of uniform isosceles triangle shape.

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 longitudinal axis and a radial central plane extending transverse to the longitudinal axis;

each die segment having an inner surface having a plurality of elongate formations facing into the interior of the mold chamber, the elongate formations extending in a direction non-parallel to the longitudinal axis; and

the formations having angled faces of slope which increases progressively with distance of the respective formation away from the radial central plane.