DE9214870U1 - Furnace system for heat treatment of metallic materials - Google Patents

Description

Description

The invention relates firstly to a furnace system for the heat treatment of metallic workpieces, with a first tunnel furnace for a high-temperature range and a second tunnel furnace for a low-temperature range, with material holders that can be moved through the tunnel furnaces to hold material to be heat-treated and with closable insertion and removal openings for inserting the material to be treated and for removing the treated material.

Such furnace systems are well known and are used, for example, as pusher furnaces for the heat treatment of malleable cast iron. The material to be treated is inserted at one end of a pusher tunnel furnace and moved through to a discharge opening during the entire dwell time. The problem here is the relatively large space requirement and the required large number of charging processes chained and locked one behind the other to transport the charging baskets and charging pallets loaded with the material to be heat treated. Such charging baskets and pallets are also very heavy and have a relatively short service life due to the high temperature load.

The object of the present invention is to create a furnace system of the type described at the outset which is simple in its construction while requiring little space and can be operated with a minimum of moving parts.

This object is achieved in that the high-temperature furnace and the low-temperature furnace are ring-shaped, each of the furnaces is provided with only one charging opening that can be closed with a door, and the material receptacles are designed to rotate on a central rotary connection through the furnaces, whereby in an advantageous embodiment it is provided that the high-temperature furnace and the low-temperature furnace are arranged with their charging openings opposite one another and a central charging device is provided between them, with which both furnaces can be charged continuously.

These measures create a furnace system that does not require either the push-through grates or a removal door. The round structure means that a common charging opening can be used for loading and unloading the goods to be treated or the goods being treated.

In order to prevent the inert atmosphere in the tunnel furnaces from being disturbed during loading and unloading, i.e. when opening the charging opening, it is planned that gas flame tubes and inert gas nozzles are assigned to the charging openings of the furnaces.

Further advantageous measures are described in the remaining subclaims. The invention is explained using an embodiment in the accompanying drawings.

gen and is described in more detail below; it shows:

Figure 1 shows the elevation of a furnace consisting of a high-temperature furnace, a low-temperature furnace and a furnace arranged between the two.

Charging device of existing furnace system;

Figure 2 is a plan view of a furnace system according to Figure 1.

The furnace system 10 shown in Figures 1 and 2 consists of a high-temperature furnace 11 and a low-temperature furnace 12, between which a central charging device, preferably an automatic charging device 13, is arranged. As Figure 2 shows, the high-temperature furnace 11 and the low-temperature furnace 12 are equipped with circular tunnels 15, each of which has a charging opening 36. The charging openings 36 are arranged facing each other and can each be closed with a door that can be raised and lowered.

As shown in Figure 1, the high-temperature furnace 11 and the low-temperature furnace 12 are provided with a central rotary joint 14, for example a ball rotary joint, on which a rotary support 16 supported by a support 16a is arranged so that it can rotate. Radially on the outside of the rotary support 16, an annular material holder 28 is arranged, over which the ring tunnel 15 is placed in a fixed manner. The ring tunnel 15 consists of an upper fireclay muffle 26 that is open at the bottom and a material holder 28 that closes off the fireclay muffle 26 at the bottom. To seal the ring tunnel 15

Opposite the material receptacle 28, two concentrically arranged water cups 25 are provided, which run concentrically in a ring shape on the annular material receptacle 28 and are held in sealing carriers 17.

The ring tunnel 15 and the material receiving means 28 are made of refractory material, with a large number of grate-shaped basket charging pallets 35 placed on the material receiving means 28. The rotating supports 16 are driven by rotary hearth drives 18 arranged below the furnaces 11 and 12.

The central charging machine 13 is arranged between the high-temperature furnace 11 and the low-temperature furnace 12. The central charging machine 13 consists of a trolley 20 that moves back and forth in a crane runway structure 19 that can rotate by 360°. The rotating crane runway structure 19, which is suspended at the top from a slewing ring, is supported by a crane runway frame 49 with supports 27. A fork construction 22 adapted to the basket charging pallets 35 and the heat treatment station 37 is mounted on the trolley 20, which automatically travels to the positions of loading station 41, first empty station 38 in the high-temperature furnace 11, tempering stations 44 and 45, first empty station 38 in the low-temperature furnace 12 and unloading station 42 on the charging circuit 34 and charges the basket charging pallets 35 with the annealing baskets 23 placed on them.

In order to shield the charging openings 36 of the furnaces 11 and 12 from the oxygen-containing external atmosphere while the doors 31 are open, flame curtain tubes 32 and inert gas nozzles 33 are provided, whereby nitrogen is preferably used as the inert gas and natural gas is used as the fuel for the flame curtain tubes 32. As Figure 1 shows, the flame curtain tubes 32 are un-

arranged below the charging openings 36, while inert gas nozzles 33 are arranged to the side of the charging openings 36 so that they can blow nitrogen or another inert gas tangentially in front of the charging openings 36.

The doors 31 closing the charging openings 36 are guided in vertical door guides 40 and can be moved up and down in these. To remove or insert an annealing basket 23 using the fork construction 22, as shown in the high-temperature furnace 11, the door 31 can be moved upwards in the vertical door guide 40. At the same time, the gas in the flame curtain tube 32 is ignited and the inert gas nozzles are activated. This seals the charging opening 36 from the outside. An inert atmosphere under excess pressure prevails in the ring tunnel 15, so that no oxygen can penetrate.

In order to protect the individual heat treatment stations 37 from temperature loss during the opening of the charging opening 36 and the insertion of a new, cold annealing basket 23, a large number of radially extending, profiled seals 29 are arranged within the ring tunnel 15. The profiled seals 29 have profile openings 30, the external dimensions of which essentially correspond to the external dimensions of an annealing basket 23. When the material receptacles 28 or the individual heat treatment stations 37 pass through the annealing chamber 43 of the ring tunnel 15 in cycles, the annealing baskets 23 simultaneously seal the seals 29, which act as bulkheads, in the middle.

The individual annealing chambers 43, separated from each other by the profiled seals 29, are heated indirectly by gas jet heating tubes 24. The temperatures

in the individual annealing chambers 43 can be the same or different depending on the metallurgical requirements.

As Figure 2 further shows, the central charging machine 13 is assigned two loading stations 41, on which the annealing baskets 23 filled with goods to be heat-treated can be alternately set down and picked up for insertion into the high-temperature furnace 11. To pick up the goods, the fork construction 22 - held on the trolley 20 - moves slightly radially inwards and then swings on the charging circle 34 into the area of the charging opening 36 of the furnace 11 or 12 to be occupied. After the door 31 is opened, the annealing baskets 23 filled with goods to be heat-treated, which are preferably charged in pairs on a basket charging pallet 35, are set down on the first empty station 38. After the door 31 is closed, the goods pick-up device 28 rotates two stations 37, for example in a clockwise direction. The last heat treatment station 48, on which the finished heat-treated goods are located, reaches the area of the door 31 on the first empty station 38. The annealing baskets 23 that were originally on the first empty station 38 are now in the position of the second heat treatment station 47, while the second empty station 39 is in the position of the first heat treatment station 46. The annealing batches can be reversed by one station width each during the dwell time on one of the heat treatment stations 37 in order to homogenize the respective annealing goods temperature.

After completion of the heat treatment, the annealing baskets 23 are removed from the last heat treatment station 48, which is now located at the position of the first empty station 38.

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the, removed and deposited on the first empty station 38 of the low-temperature furnace 12 by means of the central automatic charging device 13 of the charging platform 21. After closing the door 31 of the high-temperature furnace 11, the material holder 28 turns back one station, for example anti-clockwise, so that the last heat treatment station 48 that has become free now takes up the position of the second empty station 39, while the first empty station 38 comes to a stop behind the door 31. This stepping movement, in which the material is turned forward two stations when inserting and one station back when removing, always ensures a sufficiently good heat separation between the cold, newly inserted material and the hot material on the last heat treatment station 48. This insertion and removal process, which is described above using the high-temperature furnace 11, takes place in the same way in the low-temperature furnace 12.

Between the heat treatment in the high-temperature furnace 11 and the subsequent tempering or ferritization treatment in the low-temperature furnace 12, the heat-treated material can be tempered in various tempering stations 44 and 45. The tempering in the tempering stations 44 and 45 can be carried out, for example, with water, hardening oil or flowing air.

After the tempering process has been completed, the central charging machine 13 rotates on the charging circuit 34 into the area of one of the unloading stations 42, onto which the finished, heat-treated goods can then be placed for removal. The central charging machine 13 can then continue to rotate and the loading in the loading stations 41 can begin again.

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Reference symbols Furnace system 35 10 High temperature furnace 36 1 1 Low temperature furnace 37 12 Charging machine 13 Slewing ring 38 14 Ring tunnel 39 15 Rotating carrier 40 16 Support 41 16a Seal carrier 42 17 Rotary hearth drive 43 18 Crane runway 44 19 Trolley 45 20 Charging platform 46 21 Fork construction 22 Glow basket 47 23 Gas jet heating tube 24 Water cup, outside 48 25 Fireclay muffle 26 Crane runway support 49 27 Good recording 28 seal 29 Profile opening 30 door 31 Flame arrester tube 32 Inert gas nozzle 33 Charging circuit 34

Basket charging pallet Charging opening Heat treatment station

first empty station second empty station door guide
Loading area Unloading area Annealing chamber
Tempering station Tempering station First heat treatment station Second heat treatment station Last heat treatment station Crane runway frame

Claims (9)

IOB Industrial Furnace Construction GmbH 8-1115/92 Scheffelstrasse 10 28.10.1992 Weinheim Furnace system for heat treatment of metallic workpieces Expectations . Furnace system for the heat treatment of metal workpieces, with a first tunnel furnace for a high temperature range and a second tunnel furnace for a low temperature range, with material holders that can be moved through the tunnel furnaces for receiving material to be heat treated and with closable insertion and removal openings for inserting the material to be treated and for removing the treated material, characterized in that the high temperature furnace (11) and the low temperature furnace (12) are ring-shaped, each of the furnaces (11, 12) is provided with only one charging opening (36) that can be closed with a door (31), and the material holders (28) are designed to be rotatable on a central rotary connection (14) through the furnaces (11, 12). 2. Furnace system according to claim 1, characterized in that the high-temperature furnace (11) and the low-temperature furnace (12) are arranged with their charging openings (36) opposite one another and between them a central charging device (13) is provided, with which both furnaces (11, 12) can be charged continuously. 3. Furnace system according to claims 1 and 2, characterized in that each of the furnaces (11, 12) has a plurality of heat treatment stations (37), two of which are designed as empty stations (38, 39). 4. Furnace system according to claims 1 to 3, characterized in that the empty stations (38, 39) are always located in the area of the charging openings (36) . 5. Furnace system according to claims 1 to 4, characterized in that the round tunnels (15) of the furnaces (11, 12) can be heated indirectly with gas jet heating pipes (24). 6. Furnace system according to claims 1 to 5, characterized in that each furnace (11, 12) is provided with a plurality of partition walls (29) and the partition walls (29) have profile openings (30) which essentially correspond to the outer profile of a charging basket (23) receiving the material to be treated. 7. Furnace system according to claims 1 to 6, characterized in that the charging openings (36) of the Furnaces (11/12) are assigned flame curtain tubes (32) and inert gas nozzles (33). 8. Furnace system according to claims 1 to 7, characterized in that the central charging device (13) loading stations (41), unloading stations (42) and several tempering stations (44, 45) located outside the furnaces (11, 12) are assigned. 9. Furnace system according to claims 1 to 8, characterized in that the fixed round tunnels (15) of the furnaces (11, 12) consist of fixed, bottom-open fireclay muffles (26) and refractory material receptacles (28) that can be rotated relative to them, and the fireclay muffles (26) are sealed gas-tight relative to the material receptacles (28) that can be rotated in their undersides.