EP0221329B1 - Process and device for quenching annealed stock - Google Patents

Abstract

1. An apparatus for quenching material for annealing heated in a furnace, the apparatus having a quenching bath container (13) receiving a quenching medium and formed at the top with an aperture for the introduction of the material for annealing ; a tank (9) which is connected to the quenching bath container (13) via a pipe (14) ; and a pumping device (18, 19, 20) for pumping the quenching medium out of the quenching container (13) into the tank (9), characterized in that the pumping device (18, 19, 20) can be changed over to pressure operation for the accelerated flooding of the quenching bath container (13).

Description

The invention relates to a device for quenching annealing material according to the preamble of claim 1.

A generic device is known from DE-A 1 583 343 and is used there in connection with a vacuum annealing furnace. This is connected via a lock to another container, which forms the quench bath container. From the quench bath tank, two pipes with a very different cross-section lead to the tank, a shut-off valve being arranged in the pipe with the large cross-section and the pump in the pipe with the small cross-section. With the help of the pump, the quenching medium can be conveyed from the quenching bath container into the tank when the valve is closed, in order to empty the quenching bath container before introducing the annealing material.

As soon as the quench bath container is emptied and the annealing material is brought into the quench bath container, the shut-off valve is opened and the quenching medium can be returned to the quench bath container via the pipeline with the large cross-section, possibly with compressed air support.

However, such a mode of operation is only possible if the tank in which the quenching medium is temporarily stored is designed as a pressure container and, apart from the pipes through which the quenching medium flows, there are no further connections to the quenching bath container, which in turn is a vacuum vessel.

From DE-A 2 211 286 a device is known in which an annealing furnace is also fixedly arranged above the quench bath tank. The annealing furnace of this known system is designed as a hood furnace and can only be loaded from below from the direction of the quench bath tank.

In order to prevent the annealing material from coming into contact with quenching medium before heating, the quenching medium is first conveyed from the quenching bath container into a tank with the aid of a pump, so that the annealing material can be brought dry into the furnace through the quenching bath container. While the annealing material is being heated up to the quench bath temperature there, the quenching medium is conveyed back from the tank into the quenching bath tank with another pump, so that the heated annealing material can be quenched in the usual way by immersing it in the quenching medium. Since there is a lot of time available for pumping the quenching medium back into the quench bath tank, the other pump is only relatively weakly dimensioned and the connecting lines between the tank and the storage tank also have a small cross section.

Proceeding from this, it is an object of the invention to provide a device for quenching annealed material, in which it is possible to allow the quench bath container and the tank to communicate freely with one another in the area above the quenching medium.

A particularly space-saving arrangement results if the quench bath container is arranged in the tank itself. The top of the tank contains an opening that is aligned with the fill opening of the quench bath tank.

In order to completely suppress the escape of vapors and quenching medium through the filling openings, the filling opening of the quenching bath container and / or the tank is assigned a slide which can be moved back and forth between two positions, by means of which the filling opening can be closed from the floods of the quenching bath container, while at the same time Pressure equalization as a result of the vapors generated in the tank and / or the quench bath container have a ventilation opening which directs the vapors to the outside in a controlled manner.

Since, as stated above, it is advantageous to flood the quench bath container from below, the pipeline advantageously opens below the lower limit of the annealing material introduced into the quench bath container. In addition, when the quenching medium is pumped out of the quenching bath tank, air can be sucked in and consequently the quenching medium cannot be mixed with air, because the mouth of the pipeline in the quenching bath tank remains flooded in all operating settings.

Since the quenching bath itself has considerable temperatures and, under certain circumstances, may have an aggressive long-term effect, it is not readily possible to submerge the drive device for the pump device. With external drive devices, sealing problems can be avoided if the pipeline in the tank has a vertically upwardly extending pipe section, the upper opening of which is below the operationally lowest level of the quenching medium in the tank, with a propeller in the vertical pipe section from its upper opening bearing output shaft of the drive device protrudes. The drive device can thus be easily installed on the top of the tank in the extension of the pipe section without the risk that quenching medium can escape in liquid form in the area of the shaft seal.

The quenching process itself is not beneficial if the quenching medium is heavily permeated with air or foams in the tank. Such foaming of the quenching medium could be caused by the pump drawing air from the quenching bath container after emptying the quenching bath container and swirling it with the quenching medium. To avoid this effect, the drive power for the pump device could be reduced when the level in the quench bath tank falls below the lower level with the aid of a level sensor, so that the pump device is just able to prevent the quench medium from flowing back into the quench bath tank. However, it is easier to use a calibratable bypass ver Provide a bond between the tank and the quench tank, which opens into the lower part of the quench tank. As the level of the quenching medium in the quenching bath container decreases, the hydrostatic pressure difference against which the pump device conveys the quenching medium into the tank increases. As a result, the volume flow conveyed by the pump device is reduced in a corresponding manner. By appropriately calibrating the bypass connection, it can be achieved that when the lower level is reached, i.e. in the correspondingly large hydrostatic differential pressure via the bypass connection, just as much quenching medium flows back from the tank into the quenching bath tank as the pump device is able to pump out with undiminished drive power is. Depending on the cross section of the bypass connection, this state of equilibrium is reached at a more or less high level in the quench bath tank.

This type of level adjustment has the advantage that there is no need for additional switches or other mechanical elements, which is a significant advantage particularly under the difficult thermal conditions of such quench baths.

So that as little quenching medium as possible has to be constantly transported between the quench bath container and the tank, the container cross section is advantageously adapted essentially to the cross section of the annealing material or the pallet carrying the annealing material. In addition, this adaptation has the advantage that as much quenching medium as can be sprayed away is captured by the container wall even if the filler opening remains open.

To lower the annealing material into the hardening bath container or to lift it out, a lifting device is to be arranged next to the bell furnace, which has a boom that can be moved up and down in the hardening bath container and can be brought into the appropriate position by means of a vertical guide, if the boom is up protruding stand, which receives the annealed material or the pallet carrying the annealed material, it is possible with appropriate dimensioning of the length of the stand to leave the boom in the raised position within the tank or the container while the stand through the filler opening protrudes upwards, so that no additional openings need to be contained for the boom itself, through which quenching medium can possibly escape.

In this case, too, it is advantageous if the cross section of the quench bath container is adapted to the cross section of the pallet together with the extension extending therefrom in order to keep the volume of the hardening medium to be pumped as low as possible.

If oil or another combustible quenching medium is used for quenching, there is a constant risk of the quenching medium igniting on the hot annealing material. This danger can be practically completely eliminated if the container is filled with protective gas or inert gas above the quenching medium, which has been lowered to the lower level, for which purpose a pipeline opens into the container as close as possible to the liquid level of the lowered quenching medium, if now the container is flooded again, the rising quenching medium pushes the protective gas in front of it, so that the parts that have not yet been quenched are constantly flushed with protective gas. The oil vapors generated during quenching can then still come into contact with hot annealed material, but the protective gas or inert gas prevents the simultaneous entry of atmospheric oxygen and the ignition of the vapors on hot annealed material parts is reliably avoided.

• Fig. 1 eine Vorrichtung zum Abschrecken gemäß der Erfindung in einer geschnittenen Seitenansicht bei angehobenem Glühgut und abgesenktem Abschreckbad,
• Fig. 2 die Vorrichtung nach Fig. 1 mit abgesenktem Glühgut und
• Fig. 3 eine schematische Draufsicht auf die Vorrich tung nach Fig. 1, geschnitten etwa entlang einer Linie 111-111 nach Fig. 1.

In the drawing, an embodiment of the object of the invention is shown. Show it:

• 1 shows a quenching device according to the invention in a sectional side view with the annealed material raised and the quenching bath lowered,
• Fig. 2 shows the device of FIG. 1 with the annealed material and
• 3 is a schematic plan view of the device according to FIG. 1, cut approximately along a line 111-111 according to FIG. 1.

Fig. 1 shows a device 1 for quenching annealing material 2, which was previously heated outside the device 1 in a bell furnace 3 to the necessary conversion temperature. The bell furnace 3 can be displaced above the device 1 by means of two rails 4 and 5 which run horizontally at a distance from one another and perpendicular to the plane of the drawing. For this purpose, a carriage is attached to the bell furnace 3, the schematically indicated rollers 6, 7 and 8 running along the rails 4 and 5.

The device 1 for quenching the annealing material 2 contains a cuboid tank 9, which is essentially closed on all sides and has a bottom 11 and an upper cover 12 connected to the side walls of the tank 9. In the tank 9, which holds a quenching medium for the annealing material 2, there is a quenching bath container 13 which extends from the bottom 11 to just below the underside of the upper cover 12 and over the gap-shaped area 14 thus formed, freely with the interior of the Tanks 9 can communicate. A further connection between the interior of the quench bath container 13 and the interior of the tank 9 is via a pipeline 14 which opens into the quench bath container 13 at 1.5 just above the floor 11 and has a section 16 that runs vertically upward. A propeller 18 runs in the vertically upward section 16, the mouth 17 of which lies to the interior of the tank 9 a considerable distance below the upper edge of the quench bath container 13 extends vertically upward through the top cover 12. The shaft 19 is the Output shaft of a drive device attached to the top of the cover 12 in the form of an electric motor 20, through which the pro-. Peller 18 can optionally be set in revolutions in each of the two possible directions of rotation, so that, depending on the direction of rotation, the quenching medium flowing through the pipeline 14 can flow up or down in the vertical pipe section 16. The mouth 17 remains submerged in all operating situations.

Another flow connection between the interior of the tank 9 and the interior of the quench bath container 13 is via a calibratable bypass connection 21, which is also mounted in the wall of the container 13 near the bottom 11 and the opening width of which is shown by an adjustable slide (not shown) can change.

Otherwise there is no further flow connection between the container 13 and the interior of the tank 9.

In order to be able to introduce the annealing material 2 into the quench bath container 13, the upper cover 12 contains a filling opening 22 which is aligned with a corresponding area 23 of the quench bath container 13. In addition to the filling opening 22, a slide 24 is mounted, which can be pivoted about a vertical axis 25 (FIG. 3); the storage of the slide 24 so that it is in each of its two end positions, i.e. is inside the tank 9 both when the filling opening is open and when it closes the filling opening 22. The two end positions of the slide 24 are indicated schematically in FIG. 3 by 24 ′ and 24 ″. In addition, FIG. 2 shows the fill opening 22 closed by the slide 24. In FIG. 1, the slide 24 is pivoted away to the side and gives the fill opening 22 completely free.

The annealed material 2 is located on or in a workpiece carrier 26, which can be designed as a pallet or basket and can be conveyed by means of a lifting device 27 out of the muffle of the bell furnace 3, which is open at the bottom, into the quench bath container 13 or out of it. The lifting device 27 has a vertically running guide rail 28 which extends vertically upwards from the top of the cover 12. A slide 29 is guided on it in a longitudinally displaceable manner and carries a rod 31 which projects into the interior of the tank 9 through a corresponding opening in the cover 12. At the end of the rod 31 protruding into the tank 9, a horizontally extending arm 32 is attached, which in turn carries at its free end a stand 33 which is set up at its upper end for receiving the workpiece carrier 26. By means of drive devices, which are not further illustrated for the sake of clarity, the slide 29 together with the rod 31 attached to it and the arm 32 and the stand 33 can be moved from the upper position shown in FIG. 1 into the lowered position or illustrated in FIG transfer back, the boom 32 constantly remaining below the cover 12 of the tank 9 due to the dimensions of the lifting device 27. However, since the arm 32 moves vertically through the quench bath container 13, its cross section is adapted to the shape of the arm 32, as can be seen in FIG. The region 23 receiving the annealing material 2, which is cylindrical because of the workpiece carrier, is followed by a rectangular extension 34, the width and length of which is adapted to the width and length of the arm 32, so that as little dead space as possible is created. This minimizes the volume of the quench bath container 13.

Since vapors are produced when the annealing material is quenched, which, as can be seen from the functional description below, can no longer escape through the fill opening 22, a ventilation opening 35 is provided in the tank 9 near its top cover 12, to which a ventilation pipe 36 is provided is connected in order to discharge the vapors generated from the tank 9 in a controlled manner.

The system described so far from the bell furnace 3 and the device 1 works as follows: At a point remote from the device 1, the bell furnace 3 is loaded from below with the annealing material 2 arranged on the workpiece carrier 26, the workpiece carrier 26 being known and known per se For the sake of clarity, holding devices not shown are held in the interior of the muffle. After the annealing material 2 has reached the necessary temperature, the bell furnace 3 is moved on the rails 4 and 6 via the device 1. In this, the quenching medium was pumped from the quench bath tank 13 into the tank 9 by starting the drive motor 20 until a level indicated by a broken line 37 is reached in the quench bath tank 13. At the same time, the level of the quenching medium in the tank 9 rises to a level indicated by a broken line 38. It must be ensured that the level 37 is still above the mouth 15, but below the lowered workpiece holder 26. This is achieved through the adjustable bypass opening 21, through which quenching medium can flow back from the tank 9 into the quench bath container 13. The bypass opening 21 is set so that when the level 37 is reached, the amount of quenching medium flowing back through the bypass opening 21 is exactly as large as the amount of quenching medium which can be pumped out of the container 13 by means of the propeller 18 via the pipeline 14. Since the hydrostatic pressure difference between the quenching medium in the quenching bath container 13 and the tank 9 increases with increasing emptying of the quenching bath container, the conveying effect of the propeller 18 decreases at constant speed and thus generates the desired state of equilibrium between the quenching medium that is pumped out and the inflow.

When the slide 24 is open, the lifting device 27 is brought into its upper end position, in which the stand 33 engages in the corresponding receiving device of the workpiece carrier 26 and moves it down from its holding devices in the muffle raises. By reversely driving the lifting device 27, the workpiece carrier 26, together with the annealing material 2 arranged thereon, is now lowered into the largely emptied quench bath container 13 until the position shown in FIG. 2 is finally reached. Here, the cold boom 32 is already immersed in the quenching medium in the quench bath container 13; However, the hot workpiece holder 26 together with the annealing material 2 is still outside or above the water level 37 and it cannot lead to the generation of steam which could escape through the opening 22. Now the slide 24 is transferred to the closed position in which the filling opening 22 is closed from below. In Fig. 3, this is the position 24 '.

After the tank 9 has been closed in this way with respect to the underside of the bell furnace 3 and the rest of the device 1, the drive motor 21 is reversed, which up to now has constantly driven the propeller 18 in the sense of drawing off quenching medium from the quenching bath tank 13. After reversing, the propeller runs in pressure mode and accelerates the quenching medium from the tank 9 back into the quenching bath tank 13, so that the quenching medium in the quenching bath tank 13 rises from below and quenched the annealing material from below. Finally, the quenching medium overflows into the tank 9 via the upper edge of the quenching bath container 13.

The vapors and liquid splashes generated during quenching remain trapped in the tank 9 or flow out in a controlled manner via the ventilation pipe 36. In any case, they cannot get into the interior of the bell furnace via the filling opening 22.

After the annealing material 2 has been quenched, the drive motor which caused the propeller 18 to operate in the pressure mode is reversed, so that the propeller 18 now sucks the quenching medium out of the quenching bath container 13 again until the previously described equilibrium state is reached and the quenching medium reaches level 37 reached in the quench bath tank 13. The resulting level 38 in the tank 9 is still below the upper edge of the quench bath container 13, which cannot flow into the quench bath container 13 in this way.

This operating phase ensures that the quenched annealing material 2 which is now quenched can still drip inside the quench bath container 13, so that as little quenching medium as possible is dragged along with the cold annealing material 2 when it is lifted out.

To lift it out, the slide 24 is first opened again; in FIG. 3 this is the position 24 ": Then the lifting device 27 is started in the sense of lifting the slide 29 until the workpiece carrier 26 together with the cold annealing material 2 emerges from the filling opening 22 and can be removed from the stand 33 .

The slightest possible adjustment of the cross section of the quench bath container 13 to the clearance profile of the workpiece carrier 26 together with the extension 32 extending therefrom in the projection reduces the amount of quenching medium to be removed from the pump device 18, 20, so that the quench bath container is emptied to level 37 correspondingly quickly, even with low pump output. Conversely, there is also a correspondingly rapid flooding.

The arrangement described significantly reduces the risk of fire when working with oil quenching baths, since the oil vapors generated during quenching can no longer get into the hot furnace interior when mixed with atmospheric oxygen, where they can ignite under unfavorable circumstances on the inner wall. Rather, the resulting oil vapors are released into the open in a controlled manner via the exhaust line 36, without being able to come together with other hot objects. A final danger, which can arise from the contact of oil vapors with the hot quenched parts which have not yet been quenched and at the same time access of atmospheric oxygen, can be prevented by filling the container 13 with protective gas or inert gas after the quenching medium has been lowered to level 37. For this purpose, a pipeline 41 is provided which opens into the quenching container 13 at 42. As shown, the mouth 42 lies just above the level 37 in order to displace as much of the atmospheric oxygen as possible from the container 13. On the other hand, the mouth 42 should not be submerged so that no foam is formed when the protective gas is supplied, which adversely affects the quenching process.

If the container 13 is now flooded by reversing the propeller 18, oil vapors also arise on the hot parts of the annealing material 2, which in turn come into contact with the hot parts, but cannot ignite due to the lack of atmospheric oxygen. The resulting oil vapors escape in a controlled manner via the ventilation pipe 36, where they only come into contact with cold parts. In order to prevent foaming of the quenching medium, the protective gas supply via line 41 is terminated shortly before the propeller 18 is switched over to the pressure mode.

Claims (13)

1. An apparatus for quenching material for annealing heated in a furnace, the apparatus having a quenching bath container (13) receiving a quenching medium and formed at the top with an aperture for the introduction of the material for annealing; a tank (9) which is connected to the quenching bath container (13) via a pipe (14); and a pumping device (18, 19, 20) for pumping the quenching medium out of the quenching container (13) into the tank (9), characterized in that the pumping device (18, 19, 20) can be changed over to pressure operation for the accelerated flooding of the quenching bath container (13).

2. An apparatus according to claim 1, characterized in that the quenching bath container (13) is disposed in the tank (9).

3. An apparatus according to claim 2, characterized in that the top cover (12) of the tank (9) is formed with an aperture (22) in alignment with the filling aperture of the quenching bath container (13).

4. An apparatus according to claims 1 or 3, characterized in that associated with the filling aperture (22) of the quenching bath container (13) and/or the tank (9) is a slide valve (24) which can be horizontally reciprocated between two positions and by means of which the filling aperture (22) can be closed prior to the flooding of the quenching bath container (13), the tank (9) and/or the container (13) having a ventilation aperture (35).

5. An apparatus according to claim 1, characterized in that the pipe (14) discharges into the quenching bath container (13) below the bottom limit of the material for annealing (2) introduced into the quenching bath container (13).

6. An apparatus according to claim 1, characterized in that the pipe (14) has in the tank (9) a vertically upwardly extending pipe portion (16) whose top aperture (17) is disposed below the lowest level of the quenching medium in the tank (9) during operation, and extending from its top aperture (17) into the tube portion (16) is an output shaft (19), bearing a propeller (18), of a drive device (20) which cooperates with the propeller (18) to form the pumping device.

7. An apparatus according to claim 6, characterized in that the driving device (20) is attached outside the tank (9) to its top cover (12) and is formed by an electric motor.

8. An apparatus according to claim 1, characterized in that the tank (9) and the quenching bath container (13) are hydraulically connected via a cali- bratable bypass connection which extends past the pumping device (18, 19, 20) and discharges at least in the quenching bath container (13) into its permanently flooded lower zone.

9. An apparatus according to claim 1, characterized in that the cross-section of the quenching bath container (13) is substantially adapted to the cross-section of a workpiece support (26) bearing the material (2) for annealing.

10. An apparatus according to claim 1, characterized in that for lowering the material (2) for annealing into the quenching bath container (13) and lifting it out of the quenching bath container (13), a lifting device (27) is provided having an arm (32) which bears the material (2) for annealing and the workpiece support (26) and can be moved upwards and downwards by means of a vertical guide (28, 29, 31).

11. An apparatus according to claim 10, characterized in that the arm (32) bears an upwardly extending upright (33) which receives the material (2) for annealing and a workpiece support (26) bearing such material (2), and the upright (33) is of such dimensions that even in the raised position the arm (32) remains inside the tank (9) and the quenching bath container (13), while the upright (33) extends upwards through the filling aperture (22).

12. An apparatus according to claim 10, characterized in that the cross-section of the quenching bath container (13) is adapted to the cross-section of the workpiece support (26) and of the arm (32) extending away therefrom.

13. An apparatus according to claim 1, characterized in that for the introduction of protective gas a pipe (41) is connected to the container (13), the mouth (42) of the pipe being disposed in the tank (13) as close as possible above the liquid level (37) of the lowered quenching medium.

Images