The invention relates to a device and a method for descaling a workpiece that is in motion in relation to the device in a movement direction. The workpiece is in particular a hot rolled stock.
To descale workpieces, in particular hot rolled stock, spraying water at high pressure onto the surface of the workpiece is known according to the prior art. For continuous descaling of the surfaces of the workpiece, the high-pressure sprayed water is generally sprayed out of multiple nozzles of a descaler. In this context, a descaler in a hot rolling facility refers to an assembly which is provided for removing scale, i.e., contaminants made of iron oxide, from the surface of the rolled stock.
A descaler is known from WO 2005/082555 A1 using which a rolled stock in motion in relation to the descaler is descaled by blasting by means of high-pressure sprayed water. This descaler comprises at least one row of nozzle heads, which sweeps over the rolled stock width, having multiple nozzle heads, wherein each nozzle head is rotationally driven by a motor about an axis of rotation perpendicular to the rolled stock surface. Furthermore, at least two nozzles arranged off-center with respect to the axis of rotation are provided in each nozzle head, which are arranged as close as structurally possible on the circumference of the nozzle head. Such a descaler is subject to the disadvantage that an energy introduction over the width of the rolled stock can have inhomogeneities, and therefore lasting temperature strips occur on the rolled stock in the overlap region of adjacent nozzle heads. Furthermore, the nozzles on the respective nozzle heads are inclined outward by an angle of attack, which is illustrated in
A method for descaling rolled stock is known from WO 1997/27955 A1, in which a rotor descaling device is provided, by means of which a liquid jet is sprayed onto a surface to be descaled of the rolled stock. To ensure only slight cooling of the rolled stock and to create high jet pressures at low operating liquid pressure, the liquid jet is formed intermittently, i.e., temporarily stopping. Because of the interruption of the liquid jet once or multiple times, pressure peaks arise, which act as a jet pressure enhancement, whereby an improvement of the descaling effect for the rolled stock is achieved. A control disk provided for this purpose, which is provided in fluid connection with a pressure medium supply line, disadvantageously increases the structural expenditure for this descaling technology, however. Furthermore, the risk of increased material strain, in particular due to cavitation, arises upon the formation of the pressure peaks.
A device of the type in question and a method of the type in question for descaling a workpiece, which is in motion in a movement direction in relation to the device, are known from DE 10 2014 109 160 A1. For this purpose, multiple jet nozzles are provided on a rotating rotor head in the form of a nozzle holder, wherein liquid is discharged or sprayed under high pressure from the jet nozzles onto a surface of the rolled stock such that in this case the emission direction in which the liquid is sprayed from the jet nozzles always extends at an angle inclined to the movement direction of the rolled stock. Due to this inclined alignment of the discharge direction, removed scale is transported away from the rolled stock to the side from the surface of the rolled stock. However, a disadvantageously strong soiling of the facility and/or its surrounding area accompanies this.
The invention is based on the object of optimizing the descaling of a workpiece using simple means and reducing the demand for energy and the quantity of water required for this purpose.
This object is achieved by a device having the features defined in claim 1, and by a method having the features defined in claim 10. Advantageous refinements of the invention are defined in the dependent claims.
A device according to the present invention is used for descaling a workpiece moved in a movement direction in relation to the device, preferably a hot rolled stock, and comprises at least one rotor head rotatable about an axis of rotation, on which multiple jet nozzles are attached, wherein a liquid, in particular water, can be dispensed onto the workpiece at an angle of attack inclined relative to the surface of the workpiece from the jet nozzles. For this purpose, the jet nozzles are attached on the rotor head in such a way that during rotation of the rotor head about its axis of rotation, the spraying direction of the liquid distributed from the jet nozzles, with respect to a projection in a plane parallel to the surface of the workpiece, is aligned permanently opposed, i.e., at a spraying angle between 170° and 190°, preferably at a spraying angle of 180°, to the movement direction of the workpiece and at the same time the angle of attack for all jet nozzles remains consistently equal. The device comprises a collection unit, which is arranged upstream from the rotor head with respect to the movement direction of the rolled stock in such a way that both the liquid dispensed from the jet nozzles after rebounding from the surface of the workpiece and also the scale removed from the surface of the workpiece by means of the liquid are introducible in a targeted manner into this collection unit.
In the same manner, the invention also provides a method for descaling a workpiece, preferably a hot rolled stock. For this purpose, the workpiece is in motion in relation to a device in a movement direction, wherein this device has at least one rotor head rotatable about an axis of rotation, on which multiple jet nozzles are attached. While the rotor head is rotated about its axis of rotation, a liquid, in particular water, is dispensed or sprayed onto the workpiece at an angle of attack inclined to the surface of the workpiece. During rotation of the rotor head about its axis of rotation, the spraying direction of the liquid dispensed from the jet nozzles, in relation to a projection in a plane parallel to the surface of the workpiece, is aligned permanently opposed, i.e., at a spraying angle between 170° and 190°, preferably at a spraying angle of 180°, to the movement direction of the workpiece, wherein the angle of attack for all jet nozzles remains consistently equal. Furthermore, both the liquid dispensed from the jet nozzles after rebounding from the surface of the workpiece and also the scale removed from the surface of the workpiece by means of the liquid are introduced in a targeted manner into a collection unit.
The invention is based on the essential finding that it is possible by means of the arrangement of the rotor head in relation to the movement direction of the workpiece and the attachment of the jet nozzles on the rotor head to align the liquid dispensed from the jet nozzles permanently and preferably precisely opposing the movement direction of the workpiece, namely in relation to a or in a projection of the spraying direction of this liquid in a plane parallel to the surface of the workpiece. As a result thereof, scale is always removed from the surface of the workpiece by the liquid opposite to the movement direction of the workpiece, which contributes to a high efficiency of the descaling. In this regard, it is to be noted that this is because effective descaling presumes that the jet nozzles operate in a “scraping” manner, which means that the spraying direction of the jet nozzles is aligned opposing the movement direction of the workpiece. The targeted introduction of the removed scale and the liquid rebounding from the surface of the workpiece into the collection unit effectively prevents removed scale from remaining on the surface of the workpiece and being rolled back into the surface during a renewed rolling procedure. In the same manner, in this way facility components of the device according to the invention are soiled less or in the best case not at all by removed scale and/or randomly spraying liquid. Additionally, it is to be noted that the fixed attachment of the jet nozzles on the rotor head result in a substantial structural simplification of the kinematics of the rotor head, because in this way planetary gears or the like, which are otherwise provided according to the prior art for additional rotation of the jet nozzles about the longitudinal axis thereof, can be omitted.
In an advantageous refinement of the invention, the rotor head is arranged in relation to the collection unit such that the liquid is exclusively sprayed in the direction of the collection unit from the jet nozzles, with respect to a projection in a plane parallel to the surface of the workpiece. In this way, a targeted introduction of removed scale and of liquid rebounding from the surface of the workpiece after being sprayed out of the jet nozzles into the collection unit is further optimized.
In an advantageous refinement of the invention, the positioning of the rotor head in relation to the movement direction of the workpiece and the attachment of at least one jet nozzle, preferably all jet nozzles, on the rotor head are selected such that the spraying direction of at least the one jet nozzle, preferably all jet nozzles, in which the liquid is sprayed onto the workpiece, extends permanently and opposing the movement direction of the workpiece, specifically in relation to a projection of this spraying direction in a plane parallel to the surface of the workpiece. This has the result that the spraying angle between the spraying direction and the movement direction of the workpiece, in a plane parallel to the surface of the workpiece, is in a range between 170° and 190°, and preferably assumes the value of 180°. This advantageously results, in the same manner as the above-mentioned arrangement of the rotor head in relation to the collection unit, in a targeted introduction of the removed scale and the liquid rebounding from the surface of the workpiece into the collection unit, because the spraying direction of the jet nozzles does not contain any component or fraction which is oriented in the direction of a side edge of the workpiece.
An optimum energy introduction is achieved for the liquid sprayed at high pressure onto the surface of the workpiece in that a plurality of jet nozzles are attached on the rotor head each at a radial distance of a different amount from its axis of rotation, wherein a greater volume flow of liquid is also dispensed from a jet nozzle which has a greater radial distance to the axis of rotation than in comparison to a jet nozzle which has a smaller radial distance to the axis of rotation. This can be achieved in a simple manner by selection of a suitable nozzle type, and therefore accordingly a greater quantity of liquid, i.e., a greater volume flow is sprayed out of a jet nozzle which is arranged radially farther away from the axis of rotation of the rotor head. Accordingly, the energy introduction for the liquid transverse to the movement direction of the workpiece, i.e., over its width, is optimized by such a design of a majority of jet nozzles on the rotor head.
In an advantageous refinement of the invention, the rotor head is arranged inclined such that its axis of rotation is inclined diagonally at an angle with respect to an orthogonal on the surface of the workpiece. In this case, the jet nozzles are each attached fixedly on the rotor head, and therefore the angle of attack which the liquid sprayed out of the jet nozzles encloses with an orthogonal on the surface of the workpiece remains constant. The jet nozzles are preferably attached on the rotor head such that the longitudinal axes thereof extend parallel to the axis of rotation of the rotor head.
In an advantageous refinement of the invention, a first rotor head arrangement and a second jet nozzle arrangement can be provided, which are arranged in succession in relation to the movement direction of the workpiece and in particular adjoining one another.
A rotor head arrangement in the present invention is either a rotor head pair, in which one rotor head is provided in each case above and below a workpiece, i.e., on its upper side and lower side, or a rotor module pair, in which—above and below the workpiece—in each case a plurality of rotor heads are combined adjacent to one another and transversely to the movement direction of the workpiece. In a normal mode, it can be provided that liquid is sprayed onto the workpiece only from the jet nozzles of the first rotor head arrangement. In a special mode, the jet nozzles of the second jet nozzle arrangement can be switched on, and therefore liquid is also dispensed or sprayed onto the workpiece from the jet nozzles of the second jet nozzle arrangement. For this case, the jet nozzles of both the first rotor head arrangement and also the second rotor head arrangement are used to descale the workpiece. The jet nozzle arrangement of the second arrangement can differ structurally from the first rotor head arrangement. The use of both arrangements in the special mode is recommended, for example, for types of steel which are difficult to descale, or in the case of stubborn scale residues, which can arise, for example, due to contact on furnace rollers. In such an embodiment, according to which only the jet nozzles of the first rotor head arrangement are used in the normal mode, the operating medium consumption can advantageously be minimized. This applies similarly for the case in which a plurality of rotor heads—as explained—are combined to form a rotor head module. This is because in this case, only one rotor module pair is used in normal operation, wherein a further jet nozzle arrangement, which is arranged downstream in the movement direction of the workpiece, for example, is switched on as needed.
Further advantages of the invention are that the individual rotors of a rotor module may be depressurized individually and/or in groups and thus the discharge of the liquid transverse to the movement direction can be adapted to the width of the workpiece.
In one advantageous refinement of the invention, a scale detection unit having a signaling connection to a control unit can be provided, which is arranged downstream from the rotor head in relation to the movement direction of the workpiece and close to the rotor head, in order to be able to detect remaining scale on the surface of the workpiece. On the basis of the signals of this scale detection unit, the descaling quality of the workpiece is compared by means of the control unit to a predetermined target setting and then a high-pressure pump unit, which has a fluid connection to the jet nozzles of the rotor head, is suitably controlled or regulated independence thereon.
The actuation of the high-pressure pump unit can take place in such a manner that a pressure with which liquid is sprayed out of the jet nozzles onto the surface of the workpiece is set in dependence on the signals of the scale detection unit. This means that the pressure for the liquid to be sprayed out is set just high enough that a sufficient descaling quality is still achieved for the workpiece. If—viewed in the movement direction of the workpiece—at least two jet nozzle arrangements are arranged in succession, by way of said actuation, a jet nozzle arrangement which can be switched on will be switched on suitably in dependence on the signals of the scale detection unit, which corresponds to the mentioned special mode according to the invention. In comparison to a typical two-row arrangement of rotor heads or spray bars, a substantial savings in operating media is achieved by such a one-row arrangement, i.e., a single rotor head arrangement which is used in normal operation.
Due to the above-mentioned adaptation of the pressure, i.e., due to a reduction of the pressure, a reduced abrasion effect of the liquid on all surrounding materials or facility parts also results, whereby both the maintenance costs decrease and also wear of the jet nozzles themselves is reduced.
The quantity of water required for clean descaling of the workpiece can be suitably minimized by a variation of the pressure and/or the volume flow by way of the installation of a scale detection unit and the incorporation thereof into a control or regulating unit. This results in a savings of energy for the provision of high-pressure water, and also in the same manner in reduced cooling of the workpiece as a result of a reduced quantity of liquid which is sprayed onto the workpiece.
In addition, it is to be noted that a distance of the rotor head to the surface of the workpiece can be adjusted. An adaptation to different batches of workpieces having different heights is thus possible. In addition, it is also possible to set this distance of the rotor head to the surface of the workpiece in dependence on the signals of the scale detection unit. For example, in this manner, in the event of inadequate descaling quality, the distance of the rotor head to the surface of the workpiece can be reduced, and therefore a greater impact pressure in relation to the liquid sprayed thereon thus results at the surface of the workpiece. Mutatis mutandis, this also applies in reverse, according to which the distance of the rotor head to the surface of the workpiece, if the descaling quality exceeds the predetermined target value, can be at least slightly increased.
Further advantages of the invention are that it is possible by way of the collection of the scale detached from the surface of the workpiece to reduce or even preclude scale flaws due to rolling in of scale residues which fall down in an uncontrolled manner. Accordingly, scale-free, clean surfaces are achieved for a workpiece with comparatively low water consumption, whereby energy for producing the high-pressure water is saved in a substantial amount. The comparatively lower water consumption results in an increased scale particle content of the water introduced into a collection unit. In other words, the water introduced into a collection unit has a greater degree of soiling, because of a higher solid content of detached scale particles. Due to the reduced specific quantity of water which is used for the descaling of the workpiece, the required heating energy for a furnace or the required forming energy for subsequent rolling of the workpiece can be substantially reduced. Because of the temperature savings, thinner final thicknesses can thus be produced for a workpiece or hot rolled stock, and therefore the product mix can be enlarged. In addition, the service life of furnace rollers also substantially lengthens at a lower furnace temperature.
Exemplary embodiments of the invention are described in detail hereafter on the basis of a schematic simplified drawing.
In the figures:
a,
a,
Various embodiments of the invention will be described in detail hereafter with reference to
A device 10 according to the invention is used for descaling a workpiece 12, which is in motion in relation to the device 10 in a movement direction X. The workpiece 12 can be a hot rolled stock, which is moved past the device 10.
In the embodiment of
In the embodiment of
In conjunction with the collection unit 22, a lower baffle plate 23.1 is provided, which is arranged between the rotor head 14 and the collection unit 22 and directly adjoins an open region of the collection unit 22 in this case. The lower baffle plate 23.1 is attached or fastened in this case on the collection unit 22 in such a way that its free end is positioned directly above the workpiece 12 and at the same time encloses an angle δ (
The lower baffle plate 23.1 is arranged flatly rising in the direction of the collection unit 22 in accordance with the angle δ of preferably 30°. The lower baffle plate 23.1 therefore fulfills the task of a deflector plate and causes a targeted introduction of the scale and the liquid rebounding from the surface 20 into the collection unit 22.
In addition, a cover unit in the form of an upper cover plate 23.2 is provided, which extends from the collection unit 22 up to directly at the rotor head 14 and assumes the function of a cover in this case. The distance of an edge of the upper cover plate 23.2, which directly adjoins the rotor head 14, is selected in this case such that the section between the edge of the upper cover plate 23.2 and the rotor head 14 is passage-free with respect to scale particles. In the meaning of the present invention, “passage-free” means that scale particles, when they have been detached from the surface 20 of the workpiece 12 as a result of the sprayed water, cannot escape between the edge of the upper cover plate 23.2 directly adjoining the rotor head 14 and the rotor head 14. Accordingly, the upper cover plate 23.2 prevents scale or liquid rebounding from the surface 20 of the workpiece 12 from escaping upward to the surroundings. Nonetheless, it is ensured in this case that air can pass through the section between the upper cover plate 23.2 and the rotor head 14, and therefore stagnation pressure does not form below the upper cover plate 23.2 during the operation of the device 10 according to the invention.
Further relationships for the arrangement of the rotor head 14 and the jet nozzles 16 attached thereon are explained hereafter with reference to
The jet nozzles 16 are fixedly attached to an end face of the rotor head 14 opposite to the workpiece 12. In this case, the longitudinal axes L of the jet nozzles 16 are aligned parallel to the axis of rotation R of the rotor head 14. Accordingly, the spraying direction S (cf.
The axis of rotation R is arranged inclined diagonally at an angle γ (
The rotor head 14 is designed as vertically adjustable. This means that a distance A, which an intersection point of the axis of rotation R with the end face of the rotor head 14 has to the surface 20 of the workpiece 12 (
According to the examples of
It is noted separately at this point that the above-explained alignment of the spraying direction S, as shown in the illustrations according to
With respect to the rotor head 14 according to
A further embodiment of a device 10 according to the invention is shown in
The top view of
Because of the reduced applied quantity of water according to the invention with improved effectiveness at the same time, the degree of soiling of the water with scale residues and/or corresponding solid particles is elevated, and therefore a different design of the collection unit is recommended.
The introduction of removed scale and liquid rebounding after a contact with the workpiece 12 from its surface 20 into a respective collection unit 22 is assisted as explained above by the lower baffle plate 23.1 rising flatly at the angle δ and is symbolized in
Further details of the collection unit 22 result from
A bottom surface 25 of the collection unit 22 is formed inclined laterally downward in each case. In the illustration of
The collection unit 22 is connected to a drainpipe 26, for example, at both lateral edges 24. Cleaning liquid and removed scale are discharged from the collection unit 22 through the drainpipe 26 as a result of gravity, for example, into a conveyor trough (not shown), into which the drainpipe 26 opens.
The discharge of cleaning liquid and scale from the collection unit 22, specifically through the drainpipe 26, can be optimized by a conveyor unit 27, by means of which the cleaning liquid and scale inside the collection unit are conveyed in the direction of an opening of the drainpipe 26 and/or in the direction of the lateral edges 24. For this purpose, the conveyor unit 27 comprises, for example, flushing nozzles 28 (
Possible embodiments of rotor heads, which can be used, for example, in the embodiment of
For the illustration of
With respect to the embodiments according to
In the embodiment according to
In the case of a rotor module 30 according to the embodiment of
It is advantageous if the individual rotors of a rotor module can be depressurized individually and/or in groups and thus the dispensing of the liquid is adapted to the width of the workpiece.
The different distances of the respective jet nozzles 16.1, 16.2, and 16.3 are respectively identified in
The relationships just explained with reference to the illustration of
A scale detection unit 32 can be provided for the invention, which is arranged downstream from a rotor head 14 or a rotor head pair 29 or a rotor module pair, respectively, with respect to the movement direction X of the workpiece 12, wherein reference is made hereafter to a rotor head 14 for simplification, without a restriction being seen therein. In the embodiment of
The scale detection unit 32 is connected for signaling to a control unit 34 (
The illustrations of
Alternatively and notwithstanding the provision of a scale detection unit 32, it is possible for the present invention that a rotor head 14 is connected for signaling to the control unit 34. The speed with which the rotor head 14 is rotated about its axis of rotation R can accordingly also be adapted by means of the control unit 34, for example, in dependence on the feed velocity at which the workpiece is moved past the device 10 in its movement direction X, for example. By means of such an adaptation of the speed for the rotor head 14, in particular to the feed velocity of the workpiece 12 in its movement direction X, an optimum energy introduction for the liquid 18 sprayed onto the surface 20 of the workpiece 12 is achieved, specifically along the movement direction X. Such an optimum adaptation of the speed of the rotor head 14 to the feed velocity of the workpiece 12 is shown in the spraying picture according to
The invention functions as follows:
For a desired descaling of the surfaces 20 of a workpiece 12, this workpiece is in motion in relation to the device 10 according to the invention in a movement direction X. For this purpose, rotor heads 14 of the device 10 are preferably provided both on a top side and also on a bottom side of the workpiece 12, according to the embodiment of
Means (not shown) are provided, by way of which the control unit 34 receives an item of information with respect to the feed velocity of the workpiece 12 in its movement direction X. Based thereon, a desired speed for a rotor head 14 can be set by means of the control unit 34, specifically in adaptation to the feed velocity of the workpiece 12. Such an adaptation is also possible in the running production mode, if variations occur in the feed velocity for the workpiece 12. The control unit 34 can be configured by programming in such a way that such an adaptation of the speed of a rotor head 14 also takes place in a regulated manner.
On the basis of the signals of the scale detection unit 32, the pressure with which the jet nozzles 16 attached to a rotor head 14 are supplied with the liquid 18 can be set and/or adapted to a predetermined value. This means that the pressure of the liquid 18 provided for the jet nozzles 16 is set just high enough, for example, that a sufficient descaling quality is achieved, which can then be monitored by means of the scale detection unit 32. In this way, a savings of the quantity of water and energy is possible. In contrast, if it should be recognized by the control unit 34, on the basis of the signals generated by the scale detection unit 32, that the descaling quality falls below a defined setpoint value, this can be compensated for by a suitable pressure increase, by switching on a pump and/or by switching on an additional descaling unit, for example, in the form of a rotor head pair 29 or a rotor module pair 31. Such an operating sequence according to the present invention is also illustrated in the flow chart of
Additionally and/or alternatively, the change of the impact pressure can be performed by a vertical adjustment of the rotor head arrangement. This vertical adjustment is symbolized in
To carry out the present invention, it is advisable in the production of the device 10 according to the invention to select the inclination of the rotor head (cf. angle γ in
Finally, it is to be noted that a rotor head 14.3 according to the illustration of
In the rotor head 14.3 according to
In the rotor head 14.4 according to
It is apparent that the rotor heads 14.3 and/or 14.4 can also be used like a rotor head pair 29 and/or like a rotor module pair 31 according to the illustrations in
If the rotor heads 14.3 and 14.4 are used, the same spraying direction S can be achieved for the sprayed liquid 18 as shown in the illustration of
It is possible, for example, that the rotor head shown in
Moreover, it is to be noted that the rotor heads 14.3 and 14.4 according to
Number | Date | Country | Kind |
---|---|---|---|
10 2016 204 570.9 | Mar 2016 | DE | national |
10 2016 204 579.2 | Mar 2016 | DE | national |
10 2016 217 560.2 | Sep 2016 | DE | national |
10 2016 217 561.0 | Sep 2016 | DE | national |
10 2016 217 562.9 | Sep 2016 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2017/055996 | 3/14/2017 | WO | 00 |