US3199158A - Centrifugal furnace for fusion and casting under vacuum - Google Patents

Centrifugal furnace for fusion and casting under vacuum Download PDF

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Publication number
US3199158A
US3199158A US213427A US21342762A US3199158A US 3199158 A US3199158 A US 3199158A US 213427 A US213427 A US 213427A US 21342762 A US21342762 A US 21342762A US 3199158 A US3199158 A US 3199158A
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Prior art keywords
pipe
stationary
furnace
piece
tubular
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Expired - Lifetime
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US213427A
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English (en)
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Rigatti-Luchini Luchino
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/04—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated adapted for treating the charge in vacuum or special atmosphere
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C13/00—Dental prostheses; Making same
    • A61C13/20—Methods or devices for soldering, casting, moulding or melting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/06—Centrifugal casting; Casting by using centrifugal force of solid or hollow bodies in moulds rotating around an axis arranged outside the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/06—Centrifugal casting; Casting by using centrifugal force of solid or hollow bodies in moulds rotating around an axis arranged outside the mould
    • B22D13/063—Centrifugal casting; Casting by using centrifugal force of solid or hollow bodies in moulds rotating around an axis arranged outside the mould for dentistry or jewellery
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D7/00—Forming, maintaining or circulating atmospheres in heating chambers
    • F27D7/06—Forming or maintaining special atmospheres or vacuum within heating chambers

Definitions

  • This invention relates to a centrifugal furnace for fusion and casting under vacuum, particularly of alloys for dental laboratories or goldsmith alloys.
  • lt is, in fact, the object of this invention to solve in an economically convenient manner the above-mentioned problems by means of a centrifugal furnace for fusion and casting under vacuum.
  • Another object of the invention is to provide a centrifugal furnace of the above-described type in which a number of operative stages of the furnace are carried out dur inn the rotation of the furnace.
  • Still another object of the invention is to provide an ecient furnace which will be economical, of low consumption and simple in operation and maintenance; which will be resistant to wear and of long life and which will have easy accessible and replaceable parts.
  • the centrifugal furnace for fusion and casting under vacuum characterized in that it comprises a chamber defined by a hermetically closable housing, in which there is contained at least one fusion crucible, communicating with at least one fusion mold within said chamber, as Well as rotary support means for said housing, heating means for said chamber, cooling means for said housing, means for imparting a rotation Vto said housing, means for cooling said housing While the same is rotating, and furnace actuating means ⁇
  • FlG. l represents a perspective view of the external assembly of the furnace according to the preferred embodiment
  • FIG. 2 represents a section along to the furnace mean plane, in which the rear part of the device has been omitted;
  • FIG. 3 represents the rear part of the device shown in FIG. 2;
  • FlG. 5 represents a sectioned view of the cover of the housing.
  • the furnace is constituted of a box l, enclosing the supporting framework of the furnace.
  • the furnace proper comprises a cylinder 2 having a double walled skirt or jacket formed of an outer wall 3 and an inner wall 6l.
  • the bottom of cylinder 2 is, in turn, constituted of a doud,l9,l58 Patented Aug. l0, 1965 ble wall with internal bottom Wall 5 and external bottom wall e, whilst the front portion can be closed by means of a cover 7 provided likewise with a double wall jacket S having a deflector Wall 8a (FIG. 5).
  • the cover closes the cylinder 2 in a fluid-tight manner by means of the annular gasket 9 and its closing and opening movements are guided by a pair of pipes lll and ll engaging slidingly in sleeve supports l2, i3, ltand l2', i3', 14', respectively and provided at diametrally opposite sides of cover 7.
  • Pipe lll communicates with the interspace provided by the jacket 8 of cover 7 and the same applies for pipe ll on the other side of the cover (FIGS. 1 and 4).
  • Pipe l@ is connected to a rubber hose l5 which is connected with its end to the fitting i6 communicating with the jacket 3, 4 of cylinder 2, whereas the end opposite to the end connected to cover 7 of pipe ll is connected to another rubber hose ld', leading to the discharge outlet.
  • Jacket 5, 6 of the bottom of cylinder 2, communicating with jacket 3, Il, has a fitting i7 to which there is connected a llexible hose i8 leading to the cold water source which will be described below.
  • Cover 7 has further closing clamps 19, 19 (FIG. l) hinged to supports 14 and 14', respectively, with screw locking means Ztl and 2%', respectively, which enable to tightly press cover 7 against cylinder 2, thus ensuring a duid-tight closing allowing the vacuum providing suction action.
  • the furnace proper comprises, further, an internal chamber 2l surrounded by an electrical heating resistance Z2 spiral-wound around chamber 2l and immersed in a suitable refractory material 23.
  • the electrical resistance 22 is connected through the bolt 24 with the insulating electrical conductor 26, which is connected in turn with Contact terminals 27 (FIGS. l and 3) which will be described below.
  • the bolt 24, consisting preferably of copper, passes through the fluid-tight metal sleeve 25 and the electrical insulation is obtained through the insulating plastic sheath 25a, which expands radially by screwing nut 24a, thus providing the necessary xing and sealing of the conductor bolt 2d.
  • the graphite Crucible .'23 having a cylindrical vessel shape, which shows in the upper part an opening 29 for iilling with the material to be molten, said opening 29 being aligned with hole 3d provided in the refractory material and with hole 3l passing through the walls of cylinder 2, so as to enable to see through tne peep hole 32 the contents of Crucible 2S.
  • inspection hole 32 is tted with a cover 33 having an inspection opening 34.
  • a lens 35 which closes in a fluid-tight manner the inspection hole.
  • 3e is a thermocouple indicating the temperature within the furnace, which is read on the scale 38 (FIG. l) connected to the therrnocouple through conductor 37.
  • the fusion chamber 2l is surrounded by quartz layers 3@ and d@ which provide for the necessary electrical insulation.
  • Crucible 7.3 lits within the cylindrical opening of fusion chamber 2l defined by the refractory material of the electric resistance and communicates through hole 4l with the cavity l2 defined by the discoid mold 43 supported on the bracket 144 fastened on the cover 7.
  • the travel of the opening displacement of cover 7 is slightly greater than the thickness of the mold 43, whereby, in the opening position of the cover 7, the mold 42 can be easily taken off the furnace, the same removal possibility existing in connection with Crucible 28.
  • Housing 2 of the furnace is supported through brackets 45.1 and 45 (FlG. l) on the T-beam 45, the web i7 of which is hinged through bolt 48 on supporting half-rings 49 and 4a'v (PIG. 1) provided on both Sides of the web 4'7 and lxed on the rotating disc 5t) by means of lugs 51 t and 52 projecting from disc 5t? and wielded thereon.
  • Lugs 51 and 52 are arranged between the half-rings 49 and 49 and the latter are ,fastened to the said lugs 51 and 52 by bolts 53 and 54, Bolt 4S permits rotation of the beam 46 through a small, angle, the limits of which being determined by the edges 55 and 56 of the projecting lugs Sl'and 52, respectively.
  • Beam 46 can be locked in' one of its positions by means of the locking member 57 provided as a cam means and cooperating with acorresponding hole provided in the web 47 and not visible in the figure.
  • connection piece 61 of the piping for the vacuum pump which connection can be coupled with the connection 62 communicating with the vacuum pump, not visible in the figure.
  • Connection 61 is provided with a side connection @30h which there is fastened a exible hose 64 (FIG. l), the -other end of which being connected to the connection 65 communicating with housing 2 and fusion chamber 2l.
  • connection 65 is branched laterally and shows on the upper part a vacuum meter ed toV control thefvacuum reached in the fusion chamber. :Near the connection 6l there is provided al valve 67 of any known type, which is either closed or opened depending on the position in which handlel 63 is turned. The handle 65 serves also tofasten connection Y61 on connection 62.
  • Rotating support disc t) carries a toothed rim 69 in mesh with pinion 7i) of an electric motor non represented in the drawing vand connected to shaft 71 extending vertically towards the aforesaid electric motor.
  • Disc 50 is rigidly connected to the bush or rotating7 sleeve member 72 rotatable about its ,own axis through ball bearings 73, the fixed race ring of which is fastened on cylinder 74 rigidly connected to the support platform 75, which is a part of the framework of the apparatus according to this invention.
  • Bush 72 is mounted on the bush V76 rotating on axial thrust ball bearings "I7V and on ball bearing 78, the fixed race ring of which is rigidly fitted on stationary tubular member or pipe 79.
  • the ball bearing 77 rests on bottom 80, rigidly connected to the support housing 74 and showing a central hole through which there passes pipe 79 having Valateral branching 31 which is inclined thereto.
  • ⁇ Bush 72 is covered' on the upper part with a disc-shaped cover member S2 having a central hole through which there passes the pipe section or tubular piece 83 having a diameter substantially equal to, and aligned with, pipe 79.
  • Pipe ysection 83 showsan inclined branching 34 projecting as a bossV from the uppery plane of the disc member 82.
  • pipes 79 and Y85 are xed. y
  • Pipe 85 penetrates with its upper end within the pipe section 33 and is aligned with the internal pipe section or pipe piece 39 having a diameter substantially equal to the fixed internal pipe S5 and slightly spaced therefrom by a gap 90, which allows rotation of pipe S9 with respect to fixed pipe 85.
  • cap S6 On the lower part of cap S6 there is provided a helical spring 9i which pushesV downwardly a bush 92 with ring gasket 93 and ring gasket 94, which gaskets actas a sealing means between the xed-pipe 79 and the rotating member 72.
  • V'Such a packing between the rotating members can advantageously be of the Angst-Pster type.
  • the device according to the above-described embodiment is further provided with a controlling relay electrical circuit whichcan automatically control the various operations of the furnace.
  • Cooling water circulation cock is then openedand by .actuating the handle of the cam means 57 the beam dris slightly rotated in vertical plane, whereby connection 61 joins connection 62m a Huid-tightV manner and terminalsjr27V are driven into terminals 59 which, in the ⁇ meantime, have raised in their upper end actuates the vacuum pump and switches on the Contact, supplying electrical energy to the heater resistance, which starts heating the fusion chamber of the furnace.
  • the duration of the heating can be regulated by means of a specially provided heating time regulating device. Such heating time will be dependent upon the quantity of material used and nature of material involved.
  • the electrical energy supply to the heater can also be controlled by the temperature reached in the furnace, which temperature, through the thermocouple 36, causes the circuit to be broken once a predetermined temperature has been reached. Whilst heating is going on, cooling water circulation continues and the vacuum pump operates until reaching a determined vacuum pressure ⁇ Then begins the fusion stage which is started by means of a push-button of the controlling circuit.
  • the various operations are actuated by an eccentric or camshaft driven by a special motor unit, which, whilst having initially brought terminals in their upper position, now cause terminals 59 with their axially sliding shaft 63 to gradually lower as the fusion phase starts.
  • the heating terminates, when terminals S9 get detached from terminals 27 by the controlling device and at the same time the small motor, actuating the centrifugation of furnace 2 through shaft "il, pinion '7d and toothed wheel 69, is caused to operate.
  • Centrifugation is thus started, thanks to which the molten mass in the Crucible is launched in the cavity l2 of the mold through hole 4l and remains withheld in such cavity 42 during the entire rotation of the furnace until hardening of molten material in the cavity 42 is accomplished.
  • the rotating assembly weighs about kg. in this embodiment and counter-weight 58 is refulated in such a way as to conveniently equalize dynamical forces developed during the centrifugation in order to decrease stresses on supports and rotating shaft.
  • a centrifugal casting apparatus comprising,
  • a stationary frame a rotatable air tight electric furnace, bearing means for rotatably supporting said furnace on said frame and defining an axis of rotation of said furnace,
  • said bearing means including, a rotating sleeve member beneath said surface and in rigid rotatory relation therewith and coaxial with said axis of rotation, said sleeve member having an upper end and a lower end and defines an inner chamber,
  • tubular piece within and rigid with said rotating sleeve member, said tubular piece having a diameter greater than the diameter of said stationary pipe and being coaxial with and offset in the axial direction with respect to said stationary tubular member to provide a first gap between said stationary tubular member and said tubular piece,
  • cover member closing the upper end of said rotating sleeve member, said cover member having a bore receiving said tubular piece and said pipe piece providing independent passages through said cover member,
  • said electric furnace having a heating chamber offset with respect to said axis of rotation, a resistor surrounding said heating chamber, a removable Crucible within said heating chamber, a removable mold within said furnace near said Crucible, duct means connecting the interior of said crucible with the interior of said mold, said mold being more distant from said axis of rotation than said heating chamber, a cooling jacket near the periphery of said furnace, an inlet opening for said cooling jacket and an outlet opening therefor,
  • first pipe means connecting said tubular piece with said inlet opening and second pipe means connecting said pipe piece with said outlet opening
  • a centrifugal casting apparatus wherein said tubular piece and said stationary pipe have equal diameters and wherein said pipe piece and said stationary pipe have equal diameters and wherein said second gap is within said tubular piece.
  • said cover has a cover cooling jacket, at least two hollow rods fixed on said cover and communicating with said cover cooling jacket of said cover, sliding supports being provided on said furnace supporting said hollow rods and allowing longitudinal displacements thereof, flexible hoses being further provided connecting said hollow rods with the cooling jacket of the furnace, said cover cooling jacket having a deector member imparting a tortuous motion to the cooling liquid owing through said cover cooling jacket.
  • said bearing means further comprise a disc member rigid with said rotating sleeve member, said disc member having a toothed rim in mesh with said transmission means, two parallel laterally spaced half-rings fixed on said disc and extending in a plane perpendicular to said disc, a beam supporting said furnace at one end thereof and having a web portion extending between said half-rings, a hinge means hingedly connecting said web portion with said half-rings, stop means limiting the rotation of said web portion about said hinge means, controllable cam means preventing rotation ofssaid web portion, an adjustable counter-weight on said beam, and wherein said further duct and valve means include a valve on the other end of said beam, a rst connecting piece on said beam Vand communicating with said valve and a Vsecond connecting piece on said stationary frame communicating With the vacuum source, said rst and said second connecting pieces communicating with each other in one position of said beam.

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Health & Medical Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • General Engineering & Computer Science (AREA)
  • Dentistry (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Dental Prosthetics (AREA)
US213427A 1961-08-05 1962-07-30 Centrifugal furnace for fusion and casting under vacuum Expired - Lifetime US3199158A (en)

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IT1448861 1961-08-05

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CH (1) CH394481A (de)
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3280434A (en) * 1964-04-22 1966-10-25 Anthony R Cecere Vacuum centrifugal jewelry making machine
US3358745A (en) * 1963-11-27 1967-12-19 Ghiorzo Vittorio Centrifugal casting machine
US3977462A (en) * 1974-05-20 1976-08-31 Isao Ohara Apparatus for producing a die cast of a complicated shape
US4247735A (en) * 1978-02-16 1981-01-27 Rigatti Luchini Luchino Electric heating crucible

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4058155A (en) * 1974-11-12 1977-11-15 Crown Manufacturing Company Portable centrifugal casting machine
IT1054581B (it) * 1975-02-08 1981-11-30 Bitter Bios Ges H Dispositivo per fondere e colare metalli in particolare per scopi dentistici in una centrifuga di colata per mezzo di un arco voltaico
DE3445424C1 (de) * 1984-12-13 1986-04-24 Rudi 7080 Aalen Körner Vorrichtung zum Giessen von Zahnersatzmaterialien

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1767023A (en) * 1928-10-03 1930-06-24 M F Patterson Dental Supply Co Centrifugal casting machine
US2637079A (en) * 1950-09-16 1953-05-05 Adolph J Kemppe Centrifugal casting device
US3052001A (en) * 1955-11-07 1962-09-04 Helen E Brennan Centrifugal casting apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1767023A (en) * 1928-10-03 1930-06-24 M F Patterson Dental Supply Co Centrifugal casting machine
US2637079A (en) * 1950-09-16 1953-05-05 Adolph J Kemppe Centrifugal casting device
US3052001A (en) * 1955-11-07 1962-09-04 Helen E Brennan Centrifugal casting apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3358745A (en) * 1963-11-27 1967-12-19 Ghiorzo Vittorio Centrifugal casting machine
US3280434A (en) * 1964-04-22 1966-10-25 Anthony R Cecere Vacuum centrifugal jewelry making machine
US3977462A (en) * 1974-05-20 1976-08-31 Isao Ohara Apparatus for producing a die cast of a complicated shape
US4247735A (en) * 1978-02-16 1981-01-27 Rigatti Luchini Luchino Electric heating crucible

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GB1015689A (en) 1966-01-05
CH394481A (de) 1965-06-30

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