Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C33/00—Feeding extrusion presses with metal to be extruded ; Loading the dummy block
  • B21C33/004—Composite billet
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/22—Making metal-coated products; Making products from two or more metals
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12229—Intermediate article [e.g., blank, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12389—All metal or with adjacent metals having variation in thickness
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component

Definitions

• the invention relates to a device for encapsulating blanks made of metallic high-temperature alloys, in particular Ti Al alloys, which are subjected to extrusion for hot forming.
• Metallic high-temperature alloys are used for the production of highly stressed or highly stressable components, for example as components for use in turbines for driving aircraft and the like. In order to achieve the desired properties, such as high strength, it is generally required for certain components that they have been hot-formed.
• TiAl alloys as a certain metallic high Temperature alloying requires the components to be reshaped, also with a view to the setting of certain structures, which cannot be achieved by other means of melting metallurgy. It has been shown that hot forming of Ti Al cast blocks requires temperatures of 1100 ° C, see Y.-W. Kim, DM Di iduk, J. etals 43 (1991) 40.
• the device should be simple and inexpensive to train and should be 1 bar.
• the encapsulation consists of at least a first inner shell, which closely encloses the blank and is spaced apart, and a second outer shell which is closely but spaced apart from the inner shell, the first and the second shell being made of a metallic one Material.
• the advantage of the solution according to the invention is that it creates an optimal shield against heat radiation from the blank, ie the core of the device, which is fundamentally the main cause of the heat losses at the present temperatures, it also advantageously being possible to achieve an optimal one To achieve thermal conduction resistance through vacuum insulation and finally advantageously to avoid convection and the avoidance of material pairings, which in the case of a Extrusion of this type required high temperatures lead to undesirable reactions.
• a bl-shaped element as the inner shell is sufficient to achieve a 33% reduction in radiated power.
• the outer shell of the device preferably has a wall thickness of 5 to 10 mm, the outer shell basically being made of steel or preferably a titanium alloy, e.g. TiA16V4, can be formed.
• the inner shell only a wall thickness in the range of 0.1 to 1 mm, but in particular advantageously a wall thickness of 0.3 mm is sufficient to achieve a reduction in the radiation power by 33%. Because of the high heating and processing temperature on the one hand but also for reasons of cost on the other hand, it is advantageous to use sheets or foils made of molybdenum and / or tantalum as the inner shell which have a low emissivity. This also avoids material combinations that lead to undesirable reactions at the high temperatures to be used.
• the blank is continuously spaced from the surrounding inner shell in order to largely avoid direct thermal contact between the blank and the inner shell.
• the webs can be created in a simple manner with a blank which is essentially cylindrical in cross section by simply twisting or milling.
• the outer shell In order to ensure, in the same way as described above, that the inner shell has a negligible thermal contact with respect to the outer shell, it is also advantageous to provide the outer shell with a plurality of projecting webs which are directed towards the inner shell and which act as a spacer to the inner shell.
• the outer casing is hollow-cylindrical in cross-section, by turning the outer casing appropriately or by milling it out.
• the webs in the outer casing and in the inner blank or core of the device are preferably to be designed in such a way that their contact area with the respectively adjacent inner casing is very small compared to the rest of the outer surface.
• the application of a single inner shell, which forms the radiation protection shield mentioned, can lead to a reduction in the radiation output of 33%.
• a third and a fourth shell which are likewise each closely spaced between the first shell and the second shell and are each closely spaced from these .
• the choice of further len will depend on the extent to which it is considered necessary for the special extrusion process, depending on the material forming the blank, to achieve the same resistance to deformation of the jacket and core material.
• the third sleeve adjacent to the first, inner sleeve with a plurality of both the first sleeve and the fourth To provide sheath-facing webs, which act as spacers to the adjacent first sheath and fourth sheath.
• the webs can be formed by correspondingly turning off or milling off the third sleeve, the corresponding, above-mentioned turning off or milling off of the blank or the outer second shell for forming the webs there, as described, remains unaffected or can be carried out in the same manner as described.
• the third casing advantageously consists of the same material as the second casing, the fourth casing advantageously consisting of the same material as the first casing.
• the radiated power is reduced to approximately 25% compared to the blank.
• the outer sheath in each case must be designed to be vacuum-tight, so that heat conduction via the gas in the interspaces as well as convection in the one Interstices are suppressed, on the other hand oxidation of the metallic parts is prevented in order to maintain the low emissivity ⁇ of these parts.
• FIG. 1 shows in section a device according to the invention with two shells which enclose a blank made of a metallic high-temperature alloy
• FIG. 2 shows an embodiment of the device of the invention according to FIG. 1, in which, however, the blank made of a metallic high-temperature alloy is enclosed by four envelopes at least in partial areas,
• 3a shows the course of a minimum and a maximum
• Fig. 4 shows the force curve during extrusion in a steel capsule with heat insulation after a waiting period of 25 seconds after heating
• FIG. 1 shows the force curve during extrusion in a steel capsule with thermal insulation after a waiting time of 50 seconds after heating.
• a device 10 is shown according to the invention, wherein the blank 11 to be subjected to extrusion made of a high-temperature metallic alloy, in particular a Ti Al alloy, has a substantially cylindrical cross section, with d correspondingly Device 10 also has a substantially cylindrical cross section.
• this shape of the blank 11 or the device 10 does not always have to be cylindrical, because many other possible configurations of the blank are also possible, which even before the final extrusion takes place later on Shape can have roughly adapted shape.
• FIGS. 1 and 2 shows the construction principles of the device 10 according to FIGS. 1 and 2 with an essentially circular cross-sectional shape.
• a blank 11 is arranged in the device 10 and surrounded by a first, inner casing 12 and a second outer casing 13, compare in particular FIG. 1.
• the casing of the blank 11 in the configuration of the device 10 according to FIG. 1 is complete, i.e. it is not only the outer, in this case cylindrical, circumferential surface of the blank 11 surrounded by the sleeves 12, 13, but also the respective flat end faces of the blank 11.
• the first, inner shell 12 closely encloses the blank 11, the inner shell 12 having, for example, a wall thickness of 0.1 to 1 mm, preferably 0.3 mm.
• the inner shell which is designed in sheet form, preferably consists of tantalum or molybdenum. Basically, however, all other are suitable Materials with low emissivity ⁇ are used, provided they do not react with the material of the blank (11) or the outer shell (18).
• the second, outer shell 13 has a much greater wall thickness than the inner shell 12, for example in the range from 5 to 10 mm. It applies to both the inner shell 12 and the outer shell 13 that the substantially flat end faces of the blank 11 are covered with the same shell structure, as described above.
• the outer shell 13 can be made of steel or any other suitable material for this purpose, for example T i AI 6V4.
• the blank 11 has a plurality of vorsp ingenden
• Web 110 which act as a spacer to the inner shell surrounding the blank 11. These webs can, for example, by milling or turning off the blank
• the webs thus formed have a width of approximately 1 mm at a height of 0.3 mm.
• 11 To suppress direct heat conduction between the blank 11 and the second, outer shell 12, including the first, inner shell 12, the webs 110 on the blank 11 and the webs 131, which are likewise formed in an analogous manner on the second outer shell 13, staggered. All in all, the entirety of the envelope made up of the first envelope 12 and the second envelope 13 thus acts as a double radiation protective shield, which reduces the power emitted by the blank 11 compared to the unprotected blank 11 to about a third.
• a third casing 14 and a fourth casing 15 are additionally provided. These sleeves 14, 15 are also arranged closely spaced from each other.
• the third casing 14, which is adjacent to the first, inner casing 12 has a plurality of webs 140 which are directed towards both the first casing 12 and the fourth casing 15.
• the webs 140 also serve as spacers to the adjacent first casing 12 and the likewise adjacent fourth casing 15.
• the third casing 14 can be made of the same material as the second casing 13.
• the fourth shell 15 can consist of the same material as the first shell 12. In fact, four radiation protection plates are effective in the configuration of the device 10 according to FIG.
• the radiated power can compared to the unprotected blank 11 can be reduced to approximately 25%, reference being made to a calculation given further below for an estimate of this reduction in the radiated power.
• Envelopes 12 and 15 are preferably made of Mo or Ta, even at temperatures higher than 1400 ° C. In principle, however, all other suitable materials with low emissivity ⁇ can also be used, provided that material pairings are avoided that lead to reactions.
• the first shell 12 and the fourth shell 15 are preferably thin-walled.
• the device according to the invention is not limited to the extrusion of Ti tanal umi niden, but of course the forming by extrusion at temperatures above 1000 ° C can be used very successfully with other metallic high-temperature alloys.
• At least the first casing 12 encloses the blank in a vacuum-tight manner, the required evacuation of the spaces between at least the first casing 12 and the blank 11 being achieved by covering the lid and the bottom of at least the first casing 12 welded in a vacuum chamber by inexpensive electron beam welding.
• the manufacture of the device 10 can thus be designed relatively inexpensively. If necessary, the other shells 13 to 15 of the device can also be designed to be vacuum-tight.
• the resulting heat losses can be prevented very effectively at high temperatures by attaching one or more radiation shields (shells) which are introduced between the hot body or blank 11 and the cold environment.
• one or more radiation shields shells which are introduced between the hot body or blank 11 and the cold environment.
• this is reduced with a radiation shield arranged concentrically around the body
• the encapsulation must be carried out according to the following principles to avoid heat loss through radiation:
• the strands were cut open and the cross-sectional shape of the Ti AI raw! i ngs 10 tracked over the length of the strand.
• the jacket and core material have the same deformation resistance sen, with the selected transducer diameter of 85 mm and the die diameter of 30 mm, circular cross sections of the Ti AI tube 10 with a diameter of 22.9 mm should result.
• 3a-3d shows the minimum and maximum diameters of the generally oval cross-sections of the Ti Al tube 10 after these tests.
• the cross section varies significantly over the length of the strand.
• the cross-sections are more approximate to the circular shape and the diameter curve over the length is more uniform, but the values are above the ideal value of 22.9 mm.
• the use of an encapsulation made of steel with thermal insulation leads to a diameter progression of 22.9 mm, whereby the most even progression is observed for the extended waiting time of 50 s.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Thermal Insulation (AREA)
• Powder Metallurgy (AREA)
• Forging (AREA)
• Superconductors And Manufacturing Methods Therefor (AREA)

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• 1997
  • 1997-10-25 DE DE19747257A patent/DE19747257C2/de not_active Expired - Fee Related
• 1998
  • 1998-08-17 DE DE59806564T patent/DE59806564D1/de not_active Expired - Lifetime
  • 1998-08-17 WO PCT/DE1998/002369 patent/WO1999021667A1/fr active IP Right Grant
  • 1998-08-17 EP EP98949898A patent/EP1024910B1/fr not_active Expired - Lifetime
  • 1998-08-17 AT AT98949898T patent/ATE228896T1/de active
• 2000
  • 2000-04-22 US US09/557,584 patent/US6420051B1/en not_active Expired - Fee Related

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