US20080277035A1

US20080277035A1 - Method and Device for Quenching Flat Steel Products

Info

Publication number: US20080277035A1
Application number: US11/664,444
Authority: US
Inventors: Friedhelm Kuhn
Original assignee: LOI Thermprocess GmbH
Current assignee: LOI Thermprocess GmbH
Priority date: 2004-10-19
Filing date: 2005-09-16
Publication date: 2008-11-13
Also published as: KR20070068383A; JP2008516777A; DE102004051047A1; KR100916192B1; CN101035913A; CN101035913B; WO2006042601A1; EP1805332A1; RU2007118673A

Abstract

An apparatus for quenching flat steel products includes a roller conveyor for such flat steel products. The roller conveyor includes upper and lower rollers. At least one nozzle device is arranged above the roller conveyor, and transversely to it, for spraying water onto the flat steel products. At least one suction removal device is arranged above the roller conveyor, and transversely to it, for removing water by suction upstream of an associated upper roller. A method of quenching flat steel products is also provided.

Description

The invention relates to a method and an apparatus for quenching flat steel products.
The main field of application of the invention is the quenching of plates of carbon steel. Frequent references are therefore made in the following description to metal plates but this is not to be seen as a limitation.
When quenching, water is sprayed onto the metal plates. The water then flows away laterally over the edges of the plate after the cooling process.
It is the object of the invention to improve the drainage of the water.
In order to solve this object, the invention provides a method of quenching flat steel products, wherein

- the flat products are conducted continuously along a roller conveyor with upper and lower rollers,
- water is sprayed onto the flat products and
- a portion of the sprayed water is removed by suction upstream of at least one of the upper rollers.

The invention is based on the recognition that a certain “sluice effect” is produced between adjacent rollers which result in an increase in the water height on the surface of the plate. The “sluice effect” can also occur between a nozzle box and the first upper roller situated downstream of it, which is frequently a spiral roller. The increase in the water level has a negative influence on the uniform cooling of the plates over the breadth of the plate and also over the length of the plate. It contributes to making the uniform flowing away of the water over the side edges of the plate more difficult. This applies, in particular, when the plates are very broad. The “sluice effect” is dependent on the amount of water per unit time and per square metre of plate surface.
The invention improves the water drainage by removing the increased water level by suction and contributes to homogenisation of the cooling of the plates over the plate breadth and also over the plate length.
The removal of the water by suction is preferably effected upstream of the first upper roller situated downstream of the spraying location. The effect of the increase in the water level is strongest at this point since the water has only a small opportunity of previously flowing away laterally over the side edges of the plate.
The water removed by suction is preferably conducted away on both sides, with respect to the direction of movement of the flat products.
There is the possibility, which is also advantageous, of again spraying the water removed by suction onto the flat products downstream of the suction removal location.
In order to solve the object posed, the invention further provides an apparatus for quenching flat steel products including

- a roller conveyor for the flat products, which includes upper and lower rollers,
- at least one nozzle device, arranged above the roller conveyor and transversely to it, for spraying water onto the flat products and
- at least one suction removal device, arranged above the roller conveyor and transversely to it, for removing water by suction upstream of an associated upper roller.

The invention preferably finds application in the first water quenching device in a continuous quencher for cooling plates of carbon steel. The nozzle device is preferably a high pressure slot nozzle with a subsequent spiral roller. It is accordingly proposed in one embodiment of the invention that the suction removal device be arranged upstream of a spiral roller. The spiral roller serves to convey the water laterally to the side edges of the plate. The suction removal of water in accordance with the invention thus promotes the drainage of water after the cooling process.
Further high pressure slot nozzle assemblies with spiral rollers arranged between them can follow the high pressure slot nozzle. These high pressure nozzle assemblies also constitute nozzle devices within the meaning of the invention, upstream of whose downstream rollers, optionally spiral rollers, the removal of water by suction can occur.
In an importance embodiment of the invention, it is proposed that the suction removal device includes a first passage, which receives the water to be removed and communicates at the top with a second passage, wherein the first passage has a constant cross-section in the upward direction over the breadth of the flat products and wherein the second passage constitutes two sections, each of which broadens from the centre of the flat products to the side and is connected to an associated suction pump.
The first passage thus results in a very uniform removal by suction of the increased water level over the breadth of the plates and the second passage ensures that the removed water can be conducted away to both sides.
It is particularly advantageous that each section of the second passage broadens such that its cross-sectional area at each position is at least as large as the total cross-sectional area of the first passage calculated from the centre of the flat products to that position. It is thus ensured with certainty that no backflow can occur at the transition between the two passages.
It is proposed in a further embodiment of the invention that the breadth of the first passage is matchable to the breadth of the flat products. This offers the possibility of using the apparatus in accordance with the invention on plates of differing breadth. The breadth of the first passage should not exceed the breadth of the plate since otherwise air is sucked in which at least impairs the removal of water.
In order to adjust the first passage, there is the possibility of constructing its side walls so as to be laterally movable whilst maintaining a seal with respect to the second passage. Alternatively, the first passage can be divided into sections which may be separately shut off.
In order to ensure that the suction opening of the first passage is reliably submersed in the accumulated water, it is proposed that the distance of the suction opening to the flat products be selected to be smaller than 10% of its breadth.
The first passage is preferably constructed in the form of a slot passage, the height of which is not more than ten times the slot thickness. It has been found that reliable, stable suction conditions may be achieved in this manner.
The first passage is preferably defined between a nozzle box of the nozzle device and an associated wall.
There is basically the possibility of constructing the suction pumps in the form of self-priming pumps. A more rapid start may, however, be effected if a vacuum device is associated with the suction pumps.
The suction pumps are preferably connected to a nozzle device situated downstream. The latter operates in the low pressure quenching region of the quencher. The removal of water by vacuum in accordance with the invention thus results in a reduction in the overall water consumption of the quencher, which is an additional advantage.

The invention will be described in more detail below by reference to a preferred exemplary embodiment in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic vertical longitudinal sectional view of an apparatus in accordance with the invention;

FIG. 2 is a plan view of the apparatus of FIG. 1.

As shown in FIG. 1, a roller conveyor is provided, which includes lower rollers 1 and upper rollers 2. The upper rollers also include a spiral roller 3. The roller conveyor serves to conduct flat products 4, in the present case plates of carbon steel, which are quenched with the apparatus in accordance with the invention and by the method in accordance with the invention, through a continuous quencher.
The apparatus in accordance with the invention includes a nozzle device 5 in the form of a high pressure slot nozzle, which is arranged above the roller conveyor and transversely to it and with which water is sprayed onto the metal plate. After the cooling process, the water should flow away on both sides over the side edges of the metal plate. This process is promoted by the spiral roller 3. However, an increase in height of the water on the plate surface occurs between the nozzle block 6 of the high pressure slot nozzle and the spiral roller 3 as a result of a “sluice effect”. This is removed by suction through a first passage 7, which communicates with a second passage 8. As may be seen in FIG. 2, the second passage 8 consists of two sections 9 and 10, which extend from the centre of the plate to each side and are connected to an associated pump. The accumulated water is thus removed upwardly by suction, in the present case vertically upwardly, and then conducted away to both sides.
The two sections 9 and 10 of the second passage 8 broaden in the outward direction in order to conduct away the water supplied by the first passage 7, the total amount of which increases in the outward direction, without backflow.
The first passage 7 is defined between the nozzle box 6 and a wall 12. It constitutes a slit passage of constant cross-section, the suction opening of which is situated so closely above the plate that it is reliably submerged in the accumulated water.
As may be seen in FIG. 2, the breadth of the first passage 7 is matched to the breadth of the plate in order to prevent air being sucked in at the sides. In order to quench narrower plates, the breadth of the first passage 7 is reduced, for instance by moving the side walls of the passage (whilst sealing the lateral regions of the second passage 8) which become exposed or by closing off individual chambers, into which the first passage may optionally be divided.
Since a “sluice effect” can also be produced downstream of the illustrated arrangement between adjacent upper rollers 2 to form a corresponding increase in water level, there is the possibility of using the water removal by suction in accordance with the invention at that point also. The same applies to increases in the water level which can form downstream of further high pressure slot nozzle assemblies provided downstream.
If there is the risk that the arrangement of the first passage 7 directly behind the high pressure slot nozzle may disrupt the nozzle flow, the first passage 7 can also be arranged downstream of the spiral roller 3.
A vacuum device can be associated with the suction pumps 11. Furthermore, the water supplied by the suction pumps 11 can be conducted in the low pressure quenching region of the quencher back onto the plate.

Claims

1-17. (canceled)

18. A method of quenching flat steel products, wherein the flat products are conducted continuously along a roller conveyor, the roller conveyor comprising upper and lower rollers, the method comprising the steps:

water is sprayed onto the flat steel products by a spraying location; and,

a portion of the sprayed water is removed by suction upstream of at least one of the upper rollers by a suction removal location.

19. A method as claimed in claim 18, characterised in that the removal of the water is effected upstream of the first upper roller, the first roller being situated downstream of the spraying location.

20. A method as claimed in claim 18, characterised in that the water removed by suction is conducted away on both sides with respect to the direction of movement of the flat steel products.

21. A method as claimed in claim 18, characterised in that the water removed by suction is again sprayed onto the flat steel products downstream of the suction removal location.

22. Apparatus for quenching flat steel products including:

a roller conveyor for associated flat steel products, the roller conveyor includes upper and lower rollers;

at least one nozzle device, arranged above the roller conveyor and transversely to it, for spraying water onto the associated flat steel products; and,

at least one suction removal device, arranged above the roller conveyor and transversely to it, for removing water by suction upstream of an associated upper roller.

23. Apparatus as claimed in claim 22, characterised in that the suction removal device is arranged between the nozzle device and the first upper roller situated downstream of it.

24. Apparatus as claimed in claim 22, characterised in that the suction removal device is arranged upstream of a spiral roller.

25. Apparatus as claimed in claim 22, characterised in that the suction removal device includes a first passage, which receives water to be removed and communicates at the top with a second passage, wherein the first passage has a constant cross-section in an upward direction over the breadth of the associated flat steel products and wherein the second passage constitutes two sections, each of which broadens from a centre of the associated flat steel products towards the side and is connected to an associated suction pump.

26. Apparatus as claimed in claim 25, characterised in that each section of the second passage broadens such that its cross-sectional area at each position is at least as large as the total cross-sectional area of the first passage calculated from the centre of the flat products to this point.

27. Apparatus as claimed in claim 25, characterised in that the breadth of the first passage may be matched to the breadth of the associated flat steel products.

28. Apparatus as claimed in claim 27, characterised in that side walls of the first passage are laterally movable whilst being sealed with respect to the second passage.

29. Apparatus as claimed in claim 27, characterised in that the first passage includes sections which may be separately shut off.

30. Apparatus as claimed in claim 25, characterised in that a distance of a suction opening of the first passage to the associated flat steel products is smaller than 10% of its breadth.

31. Apparatus as claimed in claim 25, characterised in that the first passage is constructed as a slot passage, the height of which is more than ten times the slot width.

32. Apparatus as claimed in claim 31, characterised in that the first passage is defined between a nozzle box of the nozzle device and an associated wall.

33. Apparatus as claimed in claim 25, characterised in that a vacuum device is associated with the suction pumps.

34. Apparatus as claimed in claim 25, characterised in that the suction pumps are connected to a nozzle device situated downstream.