EP0194827B1 - Superplastic forming - Google Patents

Superplastic forming Download PDF

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Publication number
EP0194827B1
EP0194827B1 EP19860301667 EP86301667A EP0194827B1 EP 0194827 B1 EP0194827 B1 EP 0194827B1 EP 19860301667 EP19860301667 EP 19860301667 EP 86301667 A EP86301667 A EP 86301667A EP 0194827 B1 EP0194827 B1 EP 0194827B1
Authority
EP
European Patent Office
Prior art keywords
preform
pressure
bar
vessel
length
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19860301667
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0194827A2 (en
EP0194827A3 (en
Inventor
Robert Anthony British Aerospace P.L.C. Harding
Stanley Arthur British Aerospace P.L.C. Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems PLC
Original Assignee
British Aerospace PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Aerospace PLC filed Critical British Aerospace PLC
Publication of EP0194827A2 publication Critical patent/EP0194827A2/en
Publication of EP0194827A3 publication Critical patent/EP0194827A3/en
Application granted granted Critical
Publication of EP0194827B1 publication Critical patent/EP0194827B1/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • B21D26/053—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure characterised by the material of the blanks
    • B21D26/055—Blanks having super-plastic properties

Definitions

  • This invention relates to the manufacture of hollow vessels such as fluid containers and pressure vessels, by the superplastic expansion of a preform made of superplastically deformable metal.
  • FR-A-22 445 428 it is proposed to make a hollow tubular preform by drawing or extruding a metal disc, to subject the preform to a surface finishing process, for example polishing or 'ironing' and then, after a pre-heating step, to superplastically deform the preform to the shape of a container.
  • a surface finishing process for example polishing or 'ironing'
  • a method of making a hollow vessel for example a fluid container or pressure vessel, wherein a hollow pre-form made of superplastically deformable metal is expanded to the required shape of the vessel by applying pressure within the pre-form while maintaining it at a temperature permitting superplastic deformation of the metal, characterised in that, to make the pre-form, there is taken a length of solid superplastically deformable metal bar, and then the central region extending along and around the central axis of the length of bar is removed by machining so as to leave the pre-form with al wall having a grain structure suitable for superplastic deformation.
  • an axially extending hole is drilled in a length of solid hot-rolled titanium alloy bar.
  • the pre-form is expanded within a mould by applying a controlled pressure within the pre-form to achieve an initial expansion of the pre-form by superplastic deformation and then, with a strain rate of the pre-form metal less than that during the initial expansion and over a substantial period of time, further expansion of the preform by a creep deformation process.
  • the preform comprises a main body portion 1 which is formed by cutting a length of bar and drilling or machining it to form a blind bore.
  • the bar is hot-rolled, centreless ground pickled and produced by normal metallurgical methods from the alloy Ti 6A1 4V.
  • An end plug 2 is turned from the same rod material as the main body portion 1 and a spout 3 is formed of the same material.
  • the main body portion 1, end plug 2 and spout 3 are thoroughly degreased and then electron beam welded together to form in combination a preform 4.
  • the preform is cleaned and degreased and then placed in a mould tool comprising mould tool portions 5, 5 1.
  • the mould is formed of mild steel and prior to insertion of the preform the interior of the mould is degreased, spray coated with Yttria release agent in a solvent base, and then baked in an oven to drive off the solvent.
  • the assembled mould tool with the preform inside is placed in a stainless steel muffle box 6 which is subsequently sealed by welding, but having inlets for shielding gas and for forming gas.
  • the muffle box and its contents are then placed in a cold press. Low pressure gas is allowed to flood the muffle box via inlet 7 and the cold press is then heated electrically to a temperature of 930 °C ⁇ 5 °C and allowed to stabilise.
  • the superplastic forming temperature typically between 900 °C and 950 °C
  • argon gas at pressure is admitted to the preform via spout 3.
  • the pressure is controlled to increase gradually over a period from atmospheric to the forming pressure (typically 1.4-2.8 x 10 6 Pa (200-400 psi)) whereupon this pressure is maintained for a period to suit the super-plastic forming strain rate, and then released (the whole process taking approximately three (hours).
  • the mould is then allowed to cool to a temperature sufficiently low to allow handling and the muffle box and its contents are removed from the press and disassembled to allow removal of the formed component.
  • Ti 6A1 4V is the material employed; however, it is believed that the above described method has applications with other superplastic material.
  • the preform In design of an appropriate preform, it is the ratio of wall thickness to internal diameter that is the critical factor in determining the forming pressure cycle.
  • the preform may be shaped internally and externally by conventional machining methods, to form, for example, external lugs or internal ribs.
  • the mould tool comprises two portions of mild steel. It can however be formed of stainless steel and indeed this is preferred for it obviates the need for a muffle box.
  • the bar from which the body portion 1, plug 2 and spout 3 of the preform 4 are made can be produced by hot rolling as mentioned earlier or alternatively could be made by a forging process.
  • the hot rolling or forging will have been carried out so that, after the central bore is formed in the bar, the body portion 1 is left with a cylindrical wall in which the metallurgical grain dimensions are not too elongated in any one direction, i.e. axially or circumferentially.
  • the article to be produced is to have one or more fairly sharp corners, such as the peripheral corners where the cylindrical part of the completed pressure vessel shown in Figure 3 meets the domed end faces of the vessel, it may be preferred to so control the application of the pressure within the preform that the major part of the expansion of the preform occur by a super- plastic deformation process while the remainder, i.e. the final expansion of the preform into the sharp corners of the mould, occurs by a creep deformation process.
  • the pressure applied within the preform can be controlled to maintain a strain rate within the preform material in or around the range 10- 3 to 10- 4 S- 1 , this giving the superplastic deformation stage of the process, and then the pressure is maintained constant, or very gradually increasing, at a value producing a strain rate of around 10- 6 S- 1 for quite a large proportion (around one third say) of the overall deformation process time to produce the final creep deformation stage.
  • Figure 4 illustrates the manufacture of another hollow article, namely a two-compartment pressure vessel for use in the manufacture of cold dry air.
  • the preform comprises two cylindrical pieces of bar 41 and 42 each of which has been drilled from one end to form a blind hole therein. A radial hole is also drilled in each piece and the two are joined by a length of Titanium alloy tube 43 fixed by welding into the respective radial holes.
  • the open end of the hole in the piece 41 is closed by welding a solid Titanium alloy plug 44 therein while the open end of the hole in piece 42 is fitted with a plug 2 and spout 3 of Figure 1.
  • Both pieces 41 and 42 are then superplastically expanded by the application of pressure to spout 46 so that they take up the shape of the mould 47. After expansion, plug and spout 45 and 46 are replaced by a solid plug or possibly the spout 46 is simply sealed off and exit and entry holes (not shown) for the air to be processed are drilled in the originally closed ends of the pieces 41 and 42.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
  • Forging (AREA)
  • Powder Metallurgy (AREA)
EP19860301667 1985-03-09 1986-03-10 Superplastic forming Expired EP0194827B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8506157 1985-03-09
GB858506157A GB8506157D0 (en) 1985-03-09 1985-03-09 Superplastic forming

Publications (3)

Publication Number Publication Date
EP0194827A2 EP0194827A2 (en) 1986-09-17
EP0194827A3 EP0194827A3 (en) 1987-08-19
EP0194827B1 true EP0194827B1 (en) 1989-05-24

Family

ID=10575741

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860301667 Expired EP0194827B1 (en) 1985-03-09 1986-03-10 Superplastic forming

Country Status (7)

Country Link
EP (1) EP0194827B1 (da)
JP (1) JPH0790295B2 (da)
DE (1) DE3663458D1 (da)
DK (1) DK160000C (da)
ES (1) ES8702187A1 (da)
GB (2) GB8506157D0 (da)
NO (1) NO163598C (da)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3543523A1 (de) * 1985-12-10 1987-06-11 Messerschmitt Boelkow Blohm Verfahren zum herstellen von behaeltern durch superplastisches verformen
US5407494A (en) * 1993-12-21 1995-04-18 Crs Holdings, Inc. Method of fabricating a welded metallic duct assembly
US6182487B1 (en) * 1998-02-18 2001-02-06 Nippon Sanso Corporation Metal vessel and a fabrication method for the same
FR2772459A1 (fr) * 1998-05-14 1999-06-18 Commissariat Energie Atomique Procede de fabrication d'une enveloppe etanche et d'un reservoir etanche de stockage, et reservoir etanche de stockage
US8991683B2 (en) 2006-03-30 2015-03-31 The Boeing Company Mark-off suppression in superplastic forming and diffusion bonding
CN103769482B (zh) * 2013-10-22 2016-08-24 北京航星机器制造有限公司 一种钛合金进气道零件的整体成形方法

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB276247A (en) * 1927-02-24 1927-08-25 Ernst Asberger Improved metal blowing process
GB888461A (en) * 1956-11-14 1962-01-31 Thompson J Wolverhampton Ltd Improvements relating to a method of and means for forming an inflated hollow body from sheet or plate metal
GB1378421A (en) * 1972-01-18 1974-12-27 British Aircraft Corp Ltd Forming articles from superplastic alloys
JPS5640652B2 (da) * 1973-10-02 1981-09-22
JPS52130465A (en) * 1976-04-26 1977-11-01 Yamaha Motor Co Ltd Bulge processing method
GB2030480B (en) * 1978-09-29 1982-08-04 British Aerospace Method of making a stiffened panel
FR2453693A1 (fr) * 1979-04-13 1980-11-07 Aerospatiale Procede pour le formage d'une matiere superplastique
JPS5744431A (en) * 1980-08-30 1982-03-12 Nippon Koki Kk Formation of hot bulge and pattern or the like for pipe to be worked using metallic bead as medium

Also Published As

Publication number Publication date
NO860872L (no) 1986-09-10
ES8702187A1 (es) 1987-01-01
DK160000C (da) 1991-06-17
GB2175235A (en) 1986-11-26
NO163598C (no) 1990-06-27
DK104286A (da) 1986-09-10
EP0194827A2 (en) 1986-09-17
JPH0790295B2 (ja) 1995-10-04
ES552806A0 (es) 1987-01-01
GB2175235B (en) 1988-12-21
GB8605888D0 (en) 1986-04-16
JPS61253130A (ja) 1986-11-11
GB8506157D0 (en) 1985-04-11
NO163598B (no) 1990-03-19
DK104286D0 (da) 1986-03-07
DK160000B (da) 1991-01-14
EP0194827A3 (en) 1987-08-19
DE3663458D1 (en) 1989-06-29

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