EP0483596B1 - Vakuumofen zur Wärmebehandlung metallischer Werkstücke - Google Patents

Vakuumofen zur Wärmebehandlung metallischer Werkstücke Download PDF

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Publication number
EP0483596B1
EP0483596B1 EP91117616A EP91117616A EP0483596B1 EP 0483596 B1 EP0483596 B1 EP 0483596B1 EP 91117616 A EP91117616 A EP 91117616A EP 91117616 A EP91117616 A EP 91117616A EP 0483596 B1 EP0483596 B1 EP 0483596B1
Authority
EP
European Patent Office
Prior art keywords
gas
treatment chamber
vacuum furnace
openings
chamber
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 - Lifetime
Application number
EP91117616A
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German (de)
English (en)
French (fr)
Other versions
EP0483596A1 (de
Inventor
Gerhard Welzig
Friedrich Dr. Preisser
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.)
Evonik Operations GmbH
Original Assignee
Degussa GmbH
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 Degussa GmbH filed Critical Degussa GmbH
Publication of EP0483596A1 publication Critical patent/EP0483596A1/de
Application granted granted Critical
Publication of EP0483596B1 publication Critical patent/EP0483596B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/767—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material with forced gas circulation; Reheating thereof
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
    • 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
    • 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
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • 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
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B2005/062—Cooling elements
    • 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
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/14—Arrangements of heating devices
    • F27B2005/143—Heating rods disposed in the chamber
    • F27B2005/146—Heating rods disposed in the chamber the heating rods being in the tubes which conduct the heating 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
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • F27B2005/161—Gas inflow or outflow
    • F27B2005/164—Air supply through a set of tubes with openings
    • F27B2005/165—Controlled tubes, e.g. orientable or with closable openings
    • 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
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • F27B2005/166—Means to circulate the atmosphere
    • F27B2005/167—Means to circulate the atmosphere the atmosphere being recirculated through the treatment chamber by a turbine

Definitions

  • DE-PS 28 39 807 a generic vacuum oven is described. It consists of a cylindrical pressure housing in which there is a thermally insulated treatment chamber with heating devices.
  • the workpieces are arranged on a batch carrier in the usable space of the treatment chamber and heated to the austenitizing temperature either under vacuum or with the simultaneous circulation of a working gas.
  • the working gas is circulated by means of a blower arranged outside the treatment chamber, which draws the gas out of the treatment chamber and blows it back into the treatment chamber under pressure via a gas distribution space and the gas supply pipes emanating therefrom.
  • the gas supply pipes are arranged parallel to the main axis of the treatment chamber and surround the work space with the workpieces. In the area of the usable space, the gas supply pipes have nozzle bores for blowing the workpieces with the working gas.
  • the intake port of the fan is separated from the treatment chamber and connected to the heat exchanger located outside the treatment chamber.
  • gas outlet openings are opened in the thermally insulated walls of the treatment chamber, so that the working gas can now emerge from the treatment chamber and, after passing through the heat exchanger, can be blown back into the treatment chamber by the blower as cooling gas.
  • Such generic vacuum furnaces are used in particular for the hardening of tools and components of all types made of different types of steel. They are also suitable for other heat treatments such as Annealing and soldering can be used.
  • the quality of the heat treatment essentially depends on the type of cooling process.
  • the greatest possible homogeneity i.e. the lowest possible temperature difference between the workpieces can be achieved. In particular with large usable space dimensions, this is no longer guaranteed by the known types of blowing.
  • the properties of the heat-treated parts depend more or less on their positioning in the work space. In addition, an influence of the component shapes and sizes on the treatment result can be determined.
  • a high uniformity of the cooling process for all workpieces in a batch is achieved in that the workpieces can be blown radially and axially simultaneously during the cooling phase.
  • the direction of the axial blowing can be changed several times during a cooling process by correspondingly alternately opening and closing the two closure elements for the gas outflow openings.
  • the pipes in the area of the usable space are made of heating conductor material and connected to external power sources.
  • the heating pipes are galvanically separated from the other pipe parts by ceramic insulating pieces.
  • the problem of adapting the cooling conditions to different workpiece shapes and sizes is solved in a simple manner with the vacuum furnace according to the invention in that the ratio of the axial to radial volume flow is set to any value even during the heat treatment by only partially opening and closing the gas outflow openings of the supply pipes can be.
  • This is advantageously made possible in that the closure elements for the two gas outflow openings of a supply pipe are formed by two pieces of pipe sliding in the supply pipe, which are connected to one another by a rigid linkage.
  • the two gas outflow openings of a supply pipe can be opened and closed alternately by axially displacing the closure arrangement between two end positions.
  • the axial blowing takes place from the gas guide space through the central gas outlet opening of the intermediate floor.
  • cooling phase 2 the workpieces are blown axially in the opposite direction, the working gas then being sucked out of the usable space through the central gas passage opening in the intermediate floor.
  • the intermediate floor ensures optimal gas flow in the usable space, which ensures excellent temperature homogeneity during the entire cooling process.
  • such a closure arrangement enables the continuous adjustment of the axial volume flows during operation and also the simultaneous closing of both gas outflow openings to completely switch off the axial blowing.
  • the locking arrangements are advantageously adjusted using adjusting devices which can move the tubes axially.
  • the closure elements for the two gas outflow openings of a supply pipe are formed by a closing pipe sliding in the supply pipe, which has two openings corresponding to the gas outflow openings and which contains an axial elongated hole between these openings in the region of the nozzle bores of the supply pipe, the width of which corresponds to the diameter of the holes.
  • This closing tube is oriented in the gas supply tube so that the elongated hole clears the nozzle bores.
  • the two gas outflow openings of the gas supply pipes can be opened and closed alternately by axial displacement with this closing pipe.
  • the volume flow of the axial blowing can also be adjusted in this case while the furnace is in operation by correspondingly displacing the closing tube.
  • the openings of the closing tubes corresponding to the gas outflow openings are preferably enlarged tangentially in one direction by the width of the elongated hole.
  • the radial volume flow can thus be regulated from its maximum value to zero by rotating the locking tube about its axis.
  • the adjustment of the closing pipes is advantageously carried out with adjusting devices which can both move the pipes axially and can also rotate about their longitudinal axis by an angle which corresponds to the radial opening angle of the nozzle bores.
  • Figure 1 shows the longitudinal section through a vacuum furnace according to the invention in a vertical position. In other embodiments, horizontal configurations are also possible.
  • the vacuum furnace (1) consists of a pressure cylinder (2), which is closed at the top and bottom by dished ends.
  • the lower dished end also serves as a door (3) and can be lowered to charge the furnace.
  • the furnace (1) contains a treatment chamber (5, a fan (19) arranged above the chamber with a gas distribution space (21) and a heat exchanger (26) between the upper edge of the treatment chamber (5) and the gas distribution space (21) for cooling the working gas during
  • the furnace also has various sliding passages (17, 18, 40) in the furnace wall for the actuation of shutters and sliders for controlling the gas flows.
  • the main axis of the treatment chamber coincides with the longitudinal axis (4) of the furnace.
  • the treatment chamber (5) is formed by side walls (6), base plate (9) and cover plate (7), all of which consist of high-temperature-resistant and thermally insulating material.
  • the chamber (5) contains a space (27) which can be used for the heat treatment of the workpieces and which is delimited by imaginary surfaces (28) and end faces (29) which are arranged parallel or perpendicular to the main axis (4) of the treatment chamber (5) are.
  • an intermediate floor (10) according to the invention with a central gas passage opening (11) perpendicular to the main axis of the chamber is drawn into the chamber above the useful space (27).
  • the intermediate floor (10) separates a gas guiding space (12) from the treatment chamber.
  • the cover plate (7) of the treatment chamber is also the cover plate of the gas guide space (12) and has a central suction opening (8) which can be connected to the suction nozzle (20) of the fan (19) by means of a slide arrangement (22).
  • These gas outlet openings can be closed by flaps (14, 16). In the open state, these gas outlet openings create a connection from the gas guide space (12) to the heat exchanger (26), as shown in FIG. 2, or, as shown in FIG. 3, from the useful space (27) around the treatment chamber to the heat exchanger.
  • the slide arrangement (22) in the suction opening (8) of the cover plate (7) of the treatment chamber, as described in DE-PS 39 10 234, consists of two coaxial cylinders (23, 24) and has two switch positions I and II.
  • position I the inner cylinder (23) - as already described - is connected to the suction port (20) of the blower (19), while in position II, as shown in FIGS. 2 and 3, against a baffle plate (25) which is located in the gas guiding space (12) separated from the treatment chamber (5).
  • the blower (19) presses the working gas extracted from the treatment chamber (5) into the gas distribution space (21) and from there into gas supply pipes (31) which extend parallel to the main axis (4) into the treatment chamber (5) and between the outer surface (28) of the useful space (27) and the side walls (6) of the chamber (5) up to close to the base plate (9).
  • the gas supply pipes (31) surround the usable space in a regular arrangement.
  • the gas supply pipes (31) are provided with radially inwardly directed nozzle bores (32) in the area of the lateral surface (28) of the work space (27) for the radial blowing of the workpieces arranged in the work space on a batch carrier (30).
  • the gas supply pipes in the area of the usable space are simultaneously designed as a heater.
  • the gas supply pipes (31) in this part of the treatment chamber are made of heating conductor material and are electrically insulated from the remaining parts of the supply pipes below the intermediate floor by ceramic pipe pieces (33).
  • the axial blowing of the workpieces is achieved according to the invention by two additional radial gas outflow openings (34, 35) in each gas feed pipe (31).
  • the outflow openings are located above and below the end faces of the usable space.
  • the upper outflow openings (35) are arranged above the intermediate floor (10) in the gas guide space (12), while the lower gas outflow openings (34) of the feed pipes are located at the level of the batch carrier (30).
  • the workpieces in the usable space (27) can be alternately blown axially with the gas outflow openings (34, 35) described.
  • the upper and lower outflow openings are alternately opened and closed by closure elements (36, 37).
  • the working gas emerging from the outflow openings first flows radially inward above or below the respectively adjacent end face of the usable space and is then deflected by the pressure gradient prevailing to the opposite end face of the usable space and blows axially on the adjacent end face.
  • the batch carrier (30) does not hinder the axial blowing of the lower end face, it is made of radial spokes and is permeable to gas.
  • the closure arrangement for the outflow openings (34, 35) consists of two pipe pieces (36, 37) sliding in the supply pipes, which are rigidly connected to one another by a rod (38).
  • the rigid connection (38) of the two pipe sections is extended into the gas distribution space (21), where the closure arrangements of all gas supply pipes are connected to one another by a common frame (39).
  • Sliding devices (40) for opening and closing the gas outflow openings act on this frame (39).
  • FIG. 4a shows the arrangement of the nozzle bores (32) and gas outflow openings (34, 35) along a gas supply pipe (31).
  • Figures 4b) to 4d) show a section through the feed pipe (31) with the closure arrangement consisting of the two pipe pieces (36,37) and the connecting rod (38) in three different positions.
  • the length of the two pipe pieces is selected to be twice the diameter of the gas outflow openings (34, 35) and their distance corresponds to the distance between the outflow openings, reduced by their diameter.
  • Table 1 shows the closed states of the openings of the gas supply pipe which belong to the three positions b, c and d) of the locking arrangement.
  • Table 1 upper outflow opening (35) Nozzle bores (32) lower outflow opening (34) Position b open open closed Position c closed open closed Position d closed open open open
  • the volume flow emerging from the gas outflow openings can be set to the required values by appropriate intermediate positions.
  • the two separate tube pieces (36, 37) are replaced by a single, long closing tube (41).
  • the closing tube has openings (42, 43) for opening and closing the gas outflow openings (34, 35) of the supply tube (31), the spacing of which from one another is twice the diameter of the gas outflow openings (34, 35) smaller than the distance between the gas outflow openings.
  • the closing pipe (41) has an axial elongated hole (44) between the two openings (42, 43), the width of which corresponds to the diameter of the nozzle bores and the length of which corresponds to the distance from the outermost ones Nozzle bores plus the diameter of a nozzle bore and twice the diameter of the gas outflow openings.
  • FIG. 5 shows a gas supply pipe (31) and an associated closing pipe (41) in the working positions corresponding to FIG. 4, to which table 1 also applies.
  • the openings (42, 43) of the closing tube are enlarged tangentially by the width of the elongated hole (44).
  • the nozzle bores (32) can thus be closed without influencing the gas outflow openings.
  • the heat treatment of the workpieces takes place in three phases in the vacuum furnace according to the invention, namely heating phase, cooling phase 1 and cooling phase 2.
  • the door (3) together with the batch carrier (30) and base plate (9) of the treatment chamber (5) is lowered and the batch carrier is loaded with the workpieces.
  • the oven After closing the oven door, the oven is evacuated to approx. 1 Pa and then flooded with nitrogen. Then the heating phase begins.
  • the suction nozzle (20) of the blower (19) is connected to the treatment chamber (5) as shown in FIG. 1, ie the slide arrangement (22) is in switch position I. All gas outlet openings (13, 15) of the treatment chamber are closed, as well as the upper gas outflow openings (35) in the gas guide space (12).
  • the fan (19) circulates the working gas heated by the heating pipes via the gas distribution space (21), gas supply pipes (31), usable space (27) and gas guide space (12) in the furnace under a pressure of 0.2-0.3 MPa.
  • the flow arrows (45) in FIG. 1 illustrate the path of the working gas during heating. After a heating time of approx. 1 hour, the austenitizing temperature of the workpieces has been reached and cooling can be initiated.
  • the suction connection (20) of the fan is connected to the heat exchanger (26) as shown in FIGS. 2 and 3, i.e. the slide arrangement (22) is in switch position II and thus closes the suction opening (8) in the cover plate (7) of the treatment chamber.
  • cooling phase 1 When the workpieces cool down, the system alternates between cooling phase 1 and cooling phase 2.
  • cooling phase 2 As shown in FIG. 2, the gas outlet openings (13) of the gas guide space are opened and the upper gas outlet openings (35) of the gas supply pipes (31) as well as the gas outlet opening (15) in the base plate (9) are closed.
  • the workpieces are now blown under a pressure of 0.6-1 MPa radially and at the same time axially from the lower gas outflow openings (34) from bottom to top.
  • the working gas leaves the treatment chamber (5) through the central gas passage opening (11) of the intermediate floor (10) according to the invention and through the gas outlet openings (13) of the gas guide space (12) and is cooled as it flows past the heat exchanger (26) before it is blown by the blower (19 ) is sucked in and pressed again into the treatment chamber (see flow arrows (45) in FIG. 2).
  • cooling phase 1 As shown in FIG. 3, the gas outlet openings (13) of the gas guide space (12) and the lower gas outlet openings (34) of the supply pipes (31) are closed, while the upper gas outlet openings (35) of the supply pipes and the gas outlet opening (15 ) in the base plate (9) of the treatment chamber are open.
  • the workpieces are blown radially and at the same time axially from the upper gas outflow openings from top to bottom (see flow arrows (45) in FIG. 3).
  • the entire cooling process takes between 30 and 60 minutes depending on the size of the vacuum furnace and the type of workpiece. During this time, switching between cooling phase 1 and cooling phase 2 takes place several times.
  • the switching frequency is 1 / min.
  • the upper limit is limited to values of 2-3 / min due to the inertia of the gas masses to be switched.
  • the decisive factor for excellent temperature homogeneity for all workpieces in the usable space during the entire cooling process is the simultaneous radial and reversible axial blowing of the workpieces in the vacuum furnace according to the invention.
  • the gas flow in the treatment chamber is optimized by the intermediate floor according to the invention.
  • the optimal volume flow ratio between axial and radial blowing for many workpiece shapes and sizes is between the values 20:80 to 80:20.
  • the optimum ratio for the respective workpiece type can be set during the cooling process by only partially opening the gas outflow openings.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Furnace Details (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
EP91117616A 1990-10-26 1991-10-16 Vakuumofen zur Wärmebehandlung metallischer Werkstücke Expired - Lifetime EP0483596B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4034085A DE4034085C1 (es) 1990-10-26 1990-10-26
DE4034085 1990-10-26

Publications (2)

Publication Number Publication Date
EP0483596A1 EP0483596A1 (de) 1992-05-06
EP0483596B1 true EP0483596B1 (de) 1994-09-14

Family

ID=6417107

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91117616A Expired - Lifetime EP0483596B1 (de) 1990-10-26 1991-10-16 Vakuumofen zur Wärmebehandlung metallischer Werkstücke

Country Status (5)

Country Link
EP (1) EP0483596B1 (es)
AT (1) ATE111589T1 (es)
CZ (1) CZ282179B6 (es)
DE (2) DE4034085C1 (es)
YU (1) YU169091A (es)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4206851A1 (de) * 1992-03-05 1993-09-09 Riedhammer Gmbh Co Kg Heizrohr fuer einen industrieofen, industrieofen und verfahren zur beheizung des ofens
FR2689225A1 (fr) * 1992-03-25 1993-10-01 Stein Heurtey Physitherm Four pour traitement sous vide ou sous atmosphère gazeuse et pour trempe sous pression.
DE102005045783A1 (de) * 2005-09-23 2007-03-29 Sistem Teknik Endustriyel Elektronik Sistemler Sanayi Ve Ticaret Ltd. Sirketi Einkammer-Vakuumofen mit Wasserstoffabschreckung
DE102007029038A1 (de) * 2007-06-21 2009-01-02 Eliog-Kelvitherm Industrieofenbau Gmbh Vakuumofen zur Wärmebehandlung von metallischen Werkstücken und Verfahren zu dessen Betrieb
DE102018100745B3 (de) * 2018-01-15 2019-05-09 Ebner Industrieofenbau Gmbh Konvektionsofen
FR3102547B1 (fr) * 2019-10-24 2022-06-17 Ecm Tech Cellule de trempe sous gaz

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2839807C2 (de) * 1978-09-13 1986-04-17 Degussa Ag, 6000 Frankfurt Vakuumofen mit Gaskühleinrichtung
DE3208574A1 (de) * 1982-03-10 1983-09-22 Schmetz Industrieofenbau und Vakuum-Hartlöttechnik KG, 5750 Menden "vakuum-schachtofen"
DE3736502C1 (de) * 1987-10-28 1988-06-09 Degussa Vakuumofen zur Waermebehandlung metallischer Werkstuecke
DE3910234C1 (es) * 1989-03-30 1990-04-12 Degussa Ag, 6000 Frankfurt, De

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Publication number Publication date
CZ282179B6 (cs) 1997-05-14
CS324991A3 (en) 1992-05-13
YU169091A (sh) 1994-11-15
DE4034085C1 (es) 1991-11-14
EP0483596A1 (de) 1992-05-06
DE59102927D1 (de) 1994-10-20
ATE111589T1 (de) 1994-09-15

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