EP0332926A2 - Durchlaufofen zum Sintern von gepressten Metallpulvern - Google Patents

Durchlaufofen zum Sintern von gepressten Metallpulvern Download PDF

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Publication number
EP0332926A2
EP0332926A2 EP89103492A EP89103492A EP0332926A2 EP 0332926 A2 EP0332926 A2 EP 0332926A2 EP 89103492 A EP89103492 A EP 89103492A EP 89103492 A EP89103492 A EP 89103492A EP 0332926 A2 EP0332926 A2 EP 0332926A2
Authority
EP
European Patent Office
Prior art keywords
furnace
sealing means
metal powders
rollers
pressed metal
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.)
Withdrawn
Application number
EP89103492A
Other languages
English (en)
French (fr)
Other versions
EP0332926A3 (de
Inventor
Dante Belluzzi
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.)
NUOVA MATRIX Srl
Original Assignee
NUOVA MATRIX Srl
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 NUOVA MATRIX Srl filed Critical NUOVA MATRIX Srl
Publication of EP0332926A2 publication Critical patent/EP0332926A2/de
Publication of EP0332926A3 publication Critical patent/EP0332926A3/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0073—Seals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/003—Apparatus, e.g. furnaces
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • F27B9/045—Furnaces with controlled atmosphere
    • F27B9/047—Furnaces with controlled atmosphere the atmosphere consisting of protective gases
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace
    • F27B9/24—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace being carried by a conveyor
    • F27B9/2407—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace being carried by a conveyor the conveyor being constituted by rollers (roller hearth furnace)
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/3005—Details, accessories, or equipment peculiar to furnaces of these types arrangements for circulating gases
    • 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
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
    • F27D1/0009—Comprising ceramic fibre elements
    • 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
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D2001/0059—Construction elements of a furnace
    • F27D2001/0069—Means to prevent heat conduction
    • F27D2001/0073—Surrounding protection around the furnace, e.g. covers, circulation of gas
    • 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
    • F27D9/00—Cooling of furnaces or of charges therein
    • F27D2009/0002—Cooling of furnaces
    • F27D2009/001—Cooling of furnaces the cooling medium being a fluid other than a gas
    • F27D2009/0013—Cooling of furnaces the cooling medium being a fluid other than a gas the fluid being water
    • 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
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/02—Skids or tracks for heavy objects
    • F27D3/026—Skids or tracks for heavy objects transport or conveyor rolls for furnaces; roller rails

Definitions

  • the present invention relates to a continuous furnace for sintering pressed metal powders.
  • sintering process which consists in molding metal powders with presses and molds and in subjecting the semi-worked items to a sintering process, i.e. to annealing at a temperature lower than the metal's melting temperature: in order to provide parts with valid mechanical characteristics, sintering must occur at controlled temperatures for controlled time periods and in an atmosphere of particular gases, usually ammonia or nitrogen, to avoid oxidation phenomena.
  • the belt of the conveyor is made of stainless steel, in order to avoid oxidation phenomena, and naturally cannot operate at temperatures near its melting temperature; when working at 1030°C the belt is already subject to elongations which must be compensated by particular devices, and the elongations and contractions to which it is subject due to the temperature differences caused by its repeated entry and exit from the furnace make it deteriorate rapidly.
  • Such belt furnaces furthermore have high heat losses indeed due to the continuous entry and exit of the belt elements into and out of the furnace.
  • Roller furnaces are known and used in the ceramics industry to achieve higher operating temperatures; in these furnaces, the parts are fed by means of a plurality of rollers made of refractory material, mounted and rotatably actuated about horizontal axes and arranged transversely to the direction of the furnace.
  • Such furnaces cannot be used for sintering metal powders since an inert-gas atmosphere cannot be provided in them.
  • the technical aim of the present invention is to obviate the above described disadvantages by providing a continuous furnace which can operate at high temperatures in an inert-gas atmosphere.
  • an object of the present invention is to achieve the above described aim with a simple structure which is relatively easy to execute in practice, safe in use and effective in operation as well as relatively modest in cost.
  • a continuous furnace for sintering pressed metal powders characterized in that it comprises: a horizontally extending furnace traversed by a plurality of transverse, parallel and mutually adjacent rollers, made of refractory material, which rotatably insert in supporting holes of the walls of the furnace, said rollers having, on one side, respective sprockets mounted on their ends, said sprockets meshing with a feed chain closed in a loop and rotatably actuated by a motor-reducer unit; ducts for introducing inert gases, such as ammonia and nitrogen, in slight overpressure in the central and end regions of the furnace; sealing means mounted at the roller-furnace wall couplings, said sealing means being adapted to prevent the escape of the inert gases; burners arranged at the inlet and outlet of the furnace and adapted to eliminate by combustion any traces of oxidating gases.
  • inert gases such as ammonia and nitrogen
  • the reference numeral 1 generally indicates the continuous furnace for sintering pressed metal powders according to the inventioin.
  • the furnace 1 comprises a central high-temperature region 2, a preheating region 3 and a cooling region 4.
  • the furnace 1 is constituted by a supporting structure made of mutually assembled frames 5 which support, in the heated region, a container made of metal plate 6 which contains a wall 7 of ceramic fiber wool and a further wall 8 of light refractory bricks.
  • the parts advance in the furnace by means of a plurality of transverse rotatable rollers 9 made of refractory material, arranged mutually parallel and adjacent; the rollers are mutually coupled by means of respective sprockets 10 keyed to one of the ends of the roller and actuated by a chain, closed in a loop, and by a motor-reducer assembly, not illustrated in the figure.
  • the rollers are arranged mutually adjacent so as to produce no discontinuity which may affect the feeding of the parts; trays or containment supports of refractory material are used in any case for small-size parts.
  • the sprockets 10 extend outside the walls of the furnace, since they cannot withstand its high temperatures, and a seal is provided on the rollers by means of stuffing boxes 11 made of ceramic fiber wool 12 accommodated in metallic bushes 6a defined by the sheet metal 6; the wool is pressed against the bricks 8 on one side and by a series of containment plates 13 on the other side; said plates 13 are rigidly associated with the wall 6 by bolts 14 and are traversed by the rollers at holes 15.
  • Housings 17 are fixed on the plates 13 by means of bolts 16 and have seats for sealing gaskets 18 which act against the plates; small covers 20 are in turn coupled to the housings 17 by means of bolts 19 and allow rapid access to the rollers, to the sprockets and to the chain.
  • the high-temperature portion 2 of the furnace can be advantageously heated, instead of with resistor or gas-­fuelled burners, by silicon carbide resistors (commercially known by the name Globar), which substantially consist of cylindrical bars.
  • silicon carbide resistors commercially known by the name Globar
  • said resistors are conveniently inserted in ceramic tubes (made for example of alumina or mullite) arranged transversely to the furnace in its upper portion; this insulation of the resistors is deemed convenient in order to avoid the deposition thereon of metal vapors or oxides which may form during sintering.
  • An inert-gas atmosphere is created in the furnace by means of ducts 21 which feed ammonia and are arranged approximately halfway, at the inlet and at the outlet of the portions 2 and 4 of the furnace, and by means of the duct 22 which feeds nitrogen: the feed pressure of the inert gases is slightly higher than the atmospheric pressure to oppose the inflow of air.
  • the heating resistors are not provided in the last portion 4 of the furnace, where the parts are cooled, and an interspace 23 is defined between two slightly spaced walls 24 and 25 outside the bricks 8; said interspace is connected to inlets 26 and outlets 27 for cooling water.
  • Groups of burners are furthermore mounted at the inlet of the portion 2 and at the outlet of the portion 4; said burners are adapted to burn atmospheric oxygen to prevent it from entering the furnace and causing oxidation phenomena during sintering.
  • the preheating furnace 3 is arranged ahead of the portion 2 of the furnace, and operates with free air circulation; said furnace 3 has a hood 28, an aspirator 29 and a fume-removal duct 30, and frees the parts from any residuals of lubricants or binding agents used in the previous pressing.
  • the plane of advancement of the parts may advantageously rise slightly towards the centerline of the furnace.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Tunnel Furnaces (AREA)
EP89103492A 1988-03-15 1989-02-28 Durchlaufofen zum Sintern von gepressten Metallpulvern Withdrawn EP0332926A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT03372/88A IT1220312B (it) 1988-03-15 1988-03-15 Forno con alimentazione dei pezzi in continuo per la sinterizzazione di polveri di metalli pressate
IT337288 1988-03-15

Publications (2)

Publication Number Publication Date
EP0332926A2 true EP0332926A2 (de) 1989-09-20
EP0332926A3 EP0332926A3 (de) 1990-02-28

Family

ID=11105896

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89103492A Withdrawn EP0332926A3 (de) 1988-03-15 1989-02-28 Durchlaufofen zum Sintern von gepressten Metallpulvern

Country Status (2)

Country Link
EP (1) EP0332926A3 (de)
IT (1) IT1220312B (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9205385U1 (de) * 1992-04-18 1993-08-12 Keller Gmbh, 49479 Ibbenbueren, De
DE9205383U1 (de) * 1992-04-18 1993-09-09 Keller Gmbh Tunnelofen
DE4228006A1 (de) * 1992-08-24 1994-03-03 Ngk Insulators Ltd Rollenherd-Durchlaufofen
EP0965808A1 (de) * 1998-06-18 1999-12-22 Tecnochimica Sassolese S.r.l. Vorrichtung mit Dichtung zum Tragen und zum Antreiben von Transferrollen in einem Ofen
CN103438700A (zh) * 2013-08-02 2013-12-11 浙江吉利汽车研究院有限公司 用于热成形生产线的加热炉
CN103453770A (zh) * 2013-08-29 2013-12-18 江苏高皓工业炉有限公司 节能罩式烧结炉
CN112743076A (zh) * 2021-01-12 2021-05-04 江苏威拉里新材料科技有限公司 一种具有自动化物料收集结构的金属粉熔炼一体炉
WO2023001062A1 (zh) * 2021-07-19 2023-01-26 苏州普热斯勒先进成型技术有限公司 加热炉

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2175834A (en) * 1938-09-30 1939-10-10 Westinghouse Electric & Mfg Co Heat treating furnace
GB563225A (en) * 1943-02-05 1944-08-03 Bernard Joseph Moore Improvements in industrial kilns and ovens
US3575398A (en) * 1968-11-13 1971-04-20 Midland Ross Corp Apparatus for minimizing atmosphere upset in a furnace for heat treating articles
FR2385060A1 (fr) * 1977-03-24 1978-10-20 Autoclave Eng Inc Four a autoclave
FR2405449A1 (fr) * 1977-10-07 1979-05-04 Welko Ind Spa Support pour rouleaux tournants formant le plan d'avancement de materiaux ceramiques dans les fours de cuisson
GB2135032A (en) * 1983-02-10 1984-08-22 Boc Group Plc Heat treatment of workpieces

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2175834A (en) * 1938-09-30 1939-10-10 Westinghouse Electric & Mfg Co Heat treating furnace
GB563225A (en) * 1943-02-05 1944-08-03 Bernard Joseph Moore Improvements in industrial kilns and ovens
US3575398A (en) * 1968-11-13 1971-04-20 Midland Ross Corp Apparatus for minimizing atmosphere upset in a furnace for heat treating articles
FR2385060A1 (fr) * 1977-03-24 1978-10-20 Autoclave Eng Inc Four a autoclave
FR2405449A1 (fr) * 1977-10-07 1979-05-04 Welko Ind Spa Support pour rouleaux tournants formant le plan d'avancement de materiaux ceramiques dans les fours de cuisson
GB2135032A (en) * 1983-02-10 1984-08-22 Boc Group Plc Heat treatment of workpieces

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9205385U1 (de) * 1992-04-18 1993-08-12 Keller Gmbh, 49479 Ibbenbueren, De
DE9205383U1 (de) * 1992-04-18 1993-09-09 Keller Gmbh Tunnelofen
DE4228006A1 (de) * 1992-08-24 1994-03-03 Ngk Insulators Ltd Rollenherd-Durchlaufofen
EP0965808A1 (de) * 1998-06-18 1999-12-22 Tecnochimica Sassolese S.r.l. Vorrichtung mit Dichtung zum Tragen und zum Antreiben von Transferrollen in einem Ofen
CN103438700A (zh) * 2013-08-02 2013-12-11 浙江吉利汽车研究院有限公司 用于热成形生产线的加热炉
CN103453770A (zh) * 2013-08-29 2013-12-18 江苏高皓工业炉有限公司 节能罩式烧结炉
CN112743076A (zh) * 2021-01-12 2021-05-04 江苏威拉里新材料科技有限公司 一种具有自动化物料收集结构的金属粉熔炼一体炉
WO2023001062A1 (zh) * 2021-07-19 2023-01-26 苏州普热斯勒先进成型技术有限公司 加热炉

Also Published As

Publication number Publication date
IT1220312B (it) 1990-06-15
IT8803372A0 (it) 1988-03-15
EP0332926A3 (de) 1990-02-28

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