Device and Method for Heat Treating, in Particular, Metallic Workpieces

Abstract

The invention relates to a horizontal atmospheric furnace for heat treating, in particular, metallic workpieces at high temperatures. In order to crate a furnace that, while having a simple design and being easy to operate at the same time, enables a transfer of heat-treated workpieces into a quenching device while concluding the atmosphere surrounding the furnace, the invention provides that a horizontal atmospheric furnace for heat treating, in particular, metallic work pieces at high temperatures with a preferably cylindrical furnace chamber and with a furnace door that closes the furnace chamber in a gas-tight manner. Said furnace door is mounted in a manner that enables it to be displaced inside a door case. Which forms a lock that can be closed in a gas-tight manner.

Description

Other characteristics and advantages of the invention will result from the description made with reference to the following figures. Herein:

FIG. 1 shows a schematic cut side view of the furnace according to the invention according to a preferred embodiment and

FIG. 2 shows the furnace according to the invention in a view cut along the cutting line II-II in FIG. 1.

FIGS. 1 and 2 show the furnace according to the invention in a preferred embodiment. This one is not limiting and only serves for the exemplary detailed explanation of the functioning. The same parts in FIGS. 1 and 2 are identified by the same reference numerals.

The furnace 1 is composed of a steel housing 3, which has correspondingly formed bases 4 for a safe standing. Within the steel housing 3, the furnace chamber 2 is formed which has an insulation 5 arranged at the inner side of the steel housing 3 for a heat insulation.

For circulating the furnace chamber atmosphere, a gas circulation device in form of a ventilator 9 is arranged inside the furnace chamber 2. The ventilator 9 is driven by a motor 10 which is accessible from outside and is placed outside the furnace chamber 2. With regard to the driving, the motor 10 and the ventilator 9 are connected to each other via a no further referenced driving shaft.

The heating elements 8 formed within the furnace chamber 2 serve for the thermal treatment of a batch 11 placed inside the furnace chamber 2. The heating elements 8 are bar-shaped and extend in the longitudinal direction 20 of the furnace chamber 2. As in particular visible in FIG. 2, the totally six heating elements 8 are placed with respect to the ventilator 9 in the way of a drum turret and thus form a treatment zone 22 that is schematically represented in FIG. 2.

For carrying out a thermal treatment, the batch 11 to be thermally treated is preferably placed in the centre within the treatment zone 22. It is an advantage of this arrangement that the individual workpieces of the batch 11 are uniformly provided with heat generated by the heating elements 8, which permits the execution of a reproducible thermal treatment process.

The batch 11 is supported by a transport device 21 which is placed on rails 6 which in turn rest upon the stand 7. The transport device can be preferably displaced in the longitudinal direction 20.

The furnace chamber 2 on the face and opposite the ventilator 9 is provided with a loading and unloading opening which can be optionally opened or closed by means of a furnace door 12 that closes the chamber in a gas-tight manner. Herein, the furnace door 12 is mounted inside a door case 13 that forms a lock and within which the furnace door 12 can be displaced in the vertical direction of the door case 13. FIG. 1 shows the furnace door 12 in a position closing the loading and unloading opening of the furnace.

For creating an optionally desired furnace atmosphere, the furnace chamber 2 has a process gas supply 14 preferably on the face. Furthermore, a protective gas supply 15 can be provided, via which for example nitrogen can be introduced into the furnace chamber 2. For checking the furnace atmosphere set in the furnace chamber 2, also measuring instruments 17 can be provided.

In the case of an overpressure inside the furnace chamber 2, this one can be relieved according to the needs by means of an only schematically represented opening 18 that is closed by a pressure compensation valve. The pressure compensation valve preferably has an integrated tearing film, such that under critical overpressure conditions a corresponding pressure compensation will be automatically realized. The furnace also has a burning-off means 16 via which process gas that is present in the furnace chamber 2 can be burnt off in case of need.

It a special advantage of the furnace according to the invention that this one can be coupled in a gas-tight manner to a counter-module, for example in the form of a transport module, by means of the door case 13 that forms a gas-tight lock. Thus, while excluding the atmosphere surrounding the furnace, heated batches can be transferred from the furnace into the counter-module or from the counter-module into the furnace without any oxidation. The furnace according to the invention is operated for example by using combustible or also toxic gases, such as for example CO, such that it may be required for the transfer of a batch into the counter-module to previously sweep the atmospheric furnace with an inert protective gas, wherein the protective gas is discharged via a corresponding furnace gas pipe with burning-off. Accordingly, air is also previously swept out of the lock space of the door case 13 with an inert gas via a discharge means 23 in the door case 13.

List of Reference Numerals

• 1 furnace
• 2 furnace chamber
• 3 steel housing
• 4 base
• 5 insulation
• 6 rail
• 7 stand
• 8 heating element
• 9 ventilator
• 10 motor
• 11 batch
• 12 furnace door
• 13 doorcase
• 14 process gas supply
• 15 protective gas supply
• 16 burning-off means
• 17 measuring instrument
• 18 opening
• 19 pressure compensation valve
• 20 longitudinal direction
• 21 transport device
• 22 treatment zone
• 23 discharge means

Claims

1. A horizontal atmospheric furnace, in particular for the thermal treatment of metallic workpieces at high temperatures, comprising a preferably cylindrical furnace chamber and a furnace door (12) for closing the furnace chamber in a gas-tight manner, wherein the furnace door is mounted in a displaceable manner within a door case that forms a lock capable of being closed in a gas-tight manner.

2. The horizontal atmospheric furnace according to claim 1, wherein the door case comprises a gas-tight connection to a correspondingly formed counter-module.

3. The horizontal atmospheric furnace according to claim 1, wherein the furnace door is displaced vertically with respect to the longitudinal direction of the furnace chamber.

4. The horizontal atmospheric furnace according to claim 1, wherein the thermal treatment is conducted at a temperature between from about 400° C. to about 1050° C.

5. The horizontal atmospheric furnace according to claim 1, wherein the door case comprises a gas discharge port.

6. The horizontal atmospheric furnace according to claim 1, wherein the furnace chamber comprises gas inlets formed in the furnace chamber wall.

7. The The horizontal atmospheric furnace according to claim 1, further comprising a ventilator inside the furnace chamber.

8. The horizontal atmospheric furnace according to claim 1, further comprising a multitude of heating elements that extend in the longitudinal direction of said furnace chamber and form a treatment zone.

9. The horizontal atmospheric furnace according to claim 1, wherein the ventilator is driven by a motor, wherein the drive unit of the ventilator is placed outside said furnace chamber.

10. The horizontal atmospheric furnace according to claim 1, further comprising a transport arranged inside the furnace chamber for receiving the workpiece wherein the transport is capable of being displaced on rails in the longitudinal direction of said furnace chamber.

11. A method for the thermal treatment of a metallic workpiece in a horizontal atmospheric furnace, wherein the workpiece to be thermally treated is supplied to the atmospheric furnace by a transport chamber which is arranged in a displaceable manner with respect to the atmospheric box furnace, wherein: (A) coupling the transport chamber, which is ultimately filled with protective gas, in a gas-tight manner to the door case of the atmospheric furnace,(B) sweeping the volume space encapsulated by the door case as and, optionally, the transport chamber with a protective gas,(C) transferring the workpiece desired to be thermally treated from the transport chamber into the atmospheric box furnace in protective gas atmosphere and(D) thermally treating the workpiece transferred into the atmospheric box furnace in protective gas.

12. The method according to claim 11, wherein, subsequent to step (D), the workpiece is supplied to a quenching chamber by the transport chamber, wherein (E) the thermally treated is transferred in protective gas from the atmospheric box furnace into the transport chamber, the transport chamber having been coupled in a gas-tight manner to the atmospheric box furnace,(F) closing the transport chamber and the atmospheric box furnace in a gas-tight manner,(G) sweeping the volume space formed by the door case with nitrogen gas,(H) decoupling the transport chamber from the atmospheric box furnace,(I) displacing the transport chamber towards the quenching chamber and coupling the transport chamber in a gas-tight manner to the quenching chamber,(J) sweeping the air out of the volume space formed by the door case between transport chamber and quenching chamber with nitrogen gas,(K) transferring the workpiece in protective gas from the transport chamber into the quenching chamber after opening the doors of both chambers and(L) quenching the workpiece after closing the doors of the two chambers.

13. The method according to claim 12, wherein the atmospheric box furnace is swept with protective gas before a transfer of the workpiece into the transport chamber.

14. The method according to claim 12, wherein the transport chamber is swept with protective gas after a transfer of the workpiece into the transport chamber.

15. The horizontal atmospheric furnace according to claim 6, wherein the furnace chamber further comprises a combustion means.