Strain reduction in directed energy deposition

Abstract

A curved clamp mold and a system and method for using the curved clamp mold to fabricate objects, particularly titanium and titanium alloy objects, by directed energy deposition are provided. The method includes thermally pre-bending a substrate on which the object is to be fabricated to form a pre-bent substrate, attaching the pre-bent substrate to a fixture using the curved clamp mold as a lower support, pre-heating the substrate, and forming the object on the pre-heated pre-bent substrate using directed energy deposition techniques.

Claims

1. The first side, Two or more cavities separated by one or more reinforcing members, A rim having a flat surface around the outer circumference of the first side The first side, which includes, The second side, which is opposite to the first side, has a curved surface and includes knurling or a wave pattern, Ceramic coating and A curved clamping mold including a curved clamping mold.

2. The curved clamping mold according to claim 1, wherein the reinforcing member maintains mold rigidity, provides mold deformation resistance, or both.

3. The curved clamping mold according to claim 1 or 2, further comprising a non-magnetic metal.

4. A curved clamping mold according to any one of claims 1 to 3, further comprising a metal having a melting point of 1350°C or higher.

5. The curved clamping mold according to claim 3 or 4, wherein the metal includes austenitic stainless steel.

6. The curved clamping mold according to claim 5, wherein the austenitic stainless steel comprises carbon, chromium, copper, manganese, molybdenum, nickel, nitrogen, phosphorus, silicon, or any two or more combinations thereof.

7. The curved clamping mold according to claim 5, wherein the austenitic stainless steel contains at least 18% chromium.

8. The curved clamping mold according to claim 5, wherein the austenitic stainless steel is 300 series stainless steel.

9. The curved clamping mold according to claim 5, wherein the austenitic stainless steel includes 304 stainless steel, 309 stainless steel, 310 stainless steel, 316 stainless steel, 318 stainless steel, 321 stainless steel, or 330 stainless steel.

10. The aforementioned ceramic coating is stabilized by the addition of zirconium dioxide and yttrium oxide, and contains zirconium dioxide, yttrium aluminum oxide, alkaline earth metal silicate, and ZrV. ２ O ７ Mg ３ (VO ４ ) ２ A curved clamping mold according to any one of claims 1 to 9, or including a combination thereof.

11. The aforementioned ceramic coating is ZrO ２ 8Y ２ O ３ A curved clamping mold according to any one of claims 1 to 10, including the following:

12. The curved clamping mold according to any one of claims 1 to 11, wherein the ceramic coating has a thickness of 0.1 mm to about 5 mm.

13. A curved clamping mold according to any one of claims 1 to 12, further comprising a nominal mold deflection of approximately 3 mm to approximately 35 mm.

14. A curved clamping mold according to any one of claims 1 to 13, further comprising a bond coat on which the ceramic coating is applied.

15. A directed energy deposition method for manufacturing metal workpieces, The steps include: generating a pre-bent substrate by pre-bending a metal substrate using thermal energy, by forming a plurality of molten tracks on the first surface of the substrate using a melting tool; The lower support structure for supporting the pre-bent substrate is a curved clamping mold according to any one of claims 1 to 14, and the pre-bent substrate and the curved clamping mold supporting the pre-bent substrate are fixed to a jig using a plurality of clamps. The process includes an additive manufacturing step of forming the metal workpiece on the second surface of the substrate by melting a metal supply material to deposit a layer of molten metal on the second surface of the substrate to form a base material, and depositing a subsequent layer of molten metal on the base material to form the workpiece. Includes, A directional energy deposition method wherein the second surface of the substrate is on the opposite side of the first surface of the substrate.

16. The method according to claim 15, wherein the metal supply material is a metal in the form of powder, wire, or a combination thereof.

17. The method according to claim 15 or 16, further comprising the step of preheating the pre-bent substrate to a temperature of about 400°C to about 900°C by applying thermal energy to the second side of the substrate before forming the metal workpiece while it is fixed to the jig.

18. The method according to any one of claims 15 to 17, wherein the step of pre-bending the substrate includes inducing a temperature gradient in the substrate.

19. The method according to any one of claims 15 to 18, wherein the melting tool includes a heat source selected from a laser beam, an electron beam, a plasma arc, a gas tungsten arc, a gas metal arc, and any combination thereof.

20. The method according to any one of claims 15 to 19, wherein during the preliminary bending of the substrate, the region to which thermal energy is applied reaches a temperature that is the melting point of the metal material, or a temperature that is about 5°C to about 50°C lower or higher than the melting point of the metal material.

21. The method according to any one of claims 15 to 20, wherein, during the pre-bending of the first surface of the substrate, the formation of the molten tracks results in the formation of tensile stress at each center line of the molten tracks and the formation of compressive stress in regions of the molten tracks away from each center line during the cooling of the substrate.

22. The method according to claim 21, wherein the tensile stress at the center line of the molten track is within approximately 10% of the yield strength of the substrate.

23. The method according to claim 21, wherein the tensile stress at the center line of the molten track exceeds the magnitude of the yield strength of the substrate.

24. The method according to any one of claims 15 to 23, further comprising directing a cooling gas toward the molten track using a gas jet device to accelerate the cooling of the molten track.

25. The method according to claim 24, wherein directing the cooling gas toward the molten track creates a temperature gradient on the substrate and imparts residual stress to the substrate during cooling.

26. The method according to claim 24 or 25, wherein the gas jet device directs the cooling gas toward the molten track at a speed of approximately 50 L / min to approximately 500 L / min.

27. The method according to any one of claims 24 to 26, wherein the cooling gas is applied in a constant flow, intermittently, or in a pulsed flow.

28. The method according to any one of claims 24 to 26, wherein the cooling gas includes an inert gas selected from argon, helium, neon, xenon, krypton, and combinations thereof.

29. The method according to any one of claims 24 to 28, wherein the cooling gas is applied at a temperature of 100°C or lower.

30. The method according to any one of claims 24 to 29, wherein the cooling gas is applied at a temperature of 25°C or lower.

31. The method according to any one of claims 24 to 30, wherein the gas jet device generates turbulent flow of the cooling gas, laminar flow of the cooling gas, or a combination of turbulent and laminar flow of the cooling gas.

32. The method according to any one of claims 24 to 31, wherein the gas jet device includes a plurality of nozzles, the nozzles directing the cooling gas away from the heat source of the melting tool, and at least one nozzle directing the cooling gas to the as-solid metal of the melting track.

33. The method according to any one of claims 15 to 32, wherein the molten tracks are generated at equidistant distances from one another.

34. The method according to any one of claims 15 to 33, wherein the distance between the molten tracks is approximately 10 mm to approximately 60 mm.

35. The steps include determining the center line of each wall of the preform formed on the second surface of the substrate, The steps include positioning the molten track on the first surface of the substrate at a distance of approximately 10 mm to approximately 20 mm from the center line of most of the walls of the preform formed on the second surface of the substrate, and The method according to any one of claims 15 to 34, further comprising:

36. The method according to any one of claims 15 to 35, further comprising the step of forming the majority of the molten track on the first surface at one or more locations other than those corresponding to one or more areas occupied by one or more walls of the workpiece formed on the second side of the substrate.

37. The method according to any one of claims 15 to 36, wherein the pre-bending is used to form a pre-bent substrate having a uniform elastoplastic curvature.

38. The method according to any one of claims 15 to 37, further comprising pre-bending the substrate while the substrate is clamped to a jig and insulated from the jig.

39. The method according to any one of claims 15 to 38, wherein one or more clamps include a heat insulating coating on each surface that contacts the pre-bent substrate.

40. The method according to claim 39, wherein the thermal insulation coating comprises a ceramic material, silicon carbide, silicon nitride, boron carbide, or a combination thereof.

41. The ceramic material is alumina, zirconia, titanium oxide, alkaline earth metal silicate, aluminum titanate, zirconium dioxide stabilized by addition of yttrium oxide, yttrium aluminum oxide, ZrV ２ O ７ , Mg ３ (VO ４ ) ２ The method according to claim 40, comprising or a combination thereof.

42. The method according to claim 40 or 41, wherein the thickness of the heat insulating coating is 0.1 mm to 5 mm.

43. The method according to any one of claims 39 to 42, wherein the clamp includes a knurled pattern or a wave pattern on the surface that contacts the pre-bent substrate.

44. The method according to any one of claims 39 to 43, further comprising the step of tightening the clamp to bring the pre-bent substrate into full contact with the underlying curve clamping mold.

45. The method according to claim 44, wherein each of the clamps is tightly fastened with a torque of approximately 10 N·m to approximately 100 N·m.

46. The method according to any one of claims 39 to 45, wherein the clamp is positioned so as to coincide with the beginning or end of the wall of the workpiece being produced.

47. a) Form the molten track, but do not melt the surface of the pre-bent substrate, or b) Form the molten track and melt the surface of the pre-bent substrate in the molten track. The method according to claim 15, further comprising the step of preheating the pre-bent substrate using one or more melting tools including a DED heat source under certain conditions.

48. The method according to claim 47, further comprising the step of positioning the one or more molten tools at standoff positions higher than the standoff positions used to form the workpiece.

49. The pre-bent substrate comprises a first short edge and a second short edge on the opposite side, and a first long edge and a second long edge on the opposite side, and further includes a step of preheating before DED deposition for forming the workpiece, the preheating being, a) Positioning the melting tool, including the DED heat source, on the first short edge of the pre-bent substrate fixed to the jig, and within approximately 10 mm to approximately 60 mm of the first long edge, b) Applying the thermal energy from the DED heat source of the melting tool, starting at the first short edge and extending across the surface of the pre-bent substrate, and extending to the second short edge on the opposite side, to form a first energy application line on the surface. c) Repositioning the DED heat source of the melting tool to the first short edge and shifting it by a distance of approximately 10 mm to approximately 60 mm from the first energy application line toward the second long edge, d) Repeat steps b) and c) until the energy application line is applied across the surface of the pre-bent substrate to a position approximately 10 mm to 60 mm from the opposite second long edge. The method according to claim 48, including the method described in claim 48.

50. The method according to claim 48 or 49, further comprising the step of preheating the pre-bent substrate by applying thermal energy to the front side of the substrate using a heating device before DED deposition for forming a workpiece.

51. The method according to claim 50, wherein the heating device includes an infrared heater, an induction heater, a resistance heater, or a combination thereof.

52. The method according to claim 50, wherein the heating device includes a heat source for a conductor inside a conduit, a heater strip, a resistance heating strip, an infrared heater, a positive coefficient ceramic heater, a thick film ceramic heater, a resistance wire heater, a resistance ribbon heating device, an infrared heater, an induction heater, or a combination thereof.

53. The method according to any one of claims 47 to 52, wherein the preheating raises the temperature of the pre-bent substrate to a temperature of about 350°C to about 650°C.

54. The formation of the metal workpiece is To provide the metal supply material in the form of a wire, The wire is heated and melted using a single melting tool so that the molten metal material is deposited on the substrate region to form a base material. Moving the base material relative to the position of the melting tool in a predetermined pattern in which a continuous deposit of molten metal material on the base material solidifies and forms a three-dimensional object. The method according to any one of claims 16 to 53, including the method described in that claim.

55. The formation of the metal workpiece is a) To provide the metal supply material in the form of a wire, b) Using a first melting tool to heat at least a portion of the surface of the substrate to form a preheated area on the substrate, c) Heating and melting the wire using a second melting tool so that the molten metal material is deposited on the preheated area to form a base material, d) Moving the base material relative to the positions of the first and second melting tools in a predetermined pattern, e) Using the first melting tool to heat at least a portion of the surface of the base material to form a preheated region on the base material and melt the metal material; depositing the molten metal material produced by the second melting tool onto the preheated region on the base material; f) Repeat steps d) and e) such that a continuous deposit of molten metal material on the preheated area on the base material solidifies and forms a three-dimensional object. The method according to any one of claims 16 to 53, including the method described in that claim.

56. The steps of using a gas jet device to direct a cooling gas across the surface of the molten metal material, or onto the surface of the molten metal material, or onto the surface of the solidified material adjacent to the liquid-solid boundary of the molten metal material, or any combination thereof, The steps include moving the base material relative to the positions of the melting tool and the gas jet in a predetermined pattern in which the continuous deposits of the molten metal material solidify and form the three-dimensional object, and The method according to claim 54 or 55, further comprising:

57. The first melting tool includes a PTA torch, a laser device, an electron beam device, or any combination thereof, and The method according to claim 55, wherein the second melting tool includes a PTA torch, a laser device, a coaxial powder supply nozzle laser system, an electron beam device, or any combination thereof.

58. The first melting tool includes a first PTA torch, and the second melting tool includes a second PTA torch, or The first melting tool includes a laser device, and the second melting tool includes a PTA torch, or The first melting tool includes a PTA torch, and the second melting tool includes a laser device, or The first melting tool includes a laser device, and the second melting tool includes a coaxial powder supply nozzle laser system, or The first melting tool includes a PTA torch, and the second melting tool includes a coaxial powder supply nozzle laser system, or The first melting tool includes a PTA torch, and the second melting tool includes an electron beam device, or The first melting tool includes an electron beam device, and the second melting tool includes a PTA torch, or The first melting tool includes an electron beam device, and the second melting tool includes a laser device, or The method according to claim 57, wherein the first melting tool includes a laser device and the second melting tool includes an electron beam device.

59. The method according to claim 58, wherein, if the second melting tool includes a PTA torch, the PTA torch is electrically connected to a DC power supply such that the electrode of the PTA torch is a consumable electrode, and the metal material is a consumable electrode.

60. The method according to any one of claims 15 to 59, wherein each of the steps of pre-bending the substrate and forming the metal workpiece is carried out in a sealed chamber containing an inert atmosphere.

61. The method according to claim 60, wherein the inert atmosphere includes argon, neon, xenon, krypton, helium, or a combination thereof.

62. A jig for fixing the spare bent substrate, When the pre-bent substrate is fixed to the jig, the curved clamping mold according to any one of claims 1 to 14 is positioned between the jig and the substrate, A clamp for fixing the aforementioned pre-bent substrate to the jig, One or more melting tools including a DED heat source for melting a metal source and depositing it onto the surface of a base material, A gas jet device is used to direct a cooling gas so that it strikes the solidified material adjacent to the liquid-solid boundary of the molten pool in order to influence the temperature gradient. The cooling gas supply unit, An actuator for positioning and moving the base material relative to the melting tool and the gas jet device A system for directed energy deposition, including the above.

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