JPH0355201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relies on local tensions detected in a zone existing transversely to the strip in front of the last roll stand to perform a cooling, lubricating and/or cleaning action. By changing the amount, pressure or temperature of the liquid,
A method for rolling a strip while holding it under tension, which is carried out by thermotechnically adjusting the diameter of the roll by spraying this liquid onto the roll and controlling the temperature distribution in the axial direction of the roll; and this method. The present invention relates to an apparatus for carrying out.

It is known that when rolling cold strips of small thickness, a transverse structural flow of the material no longer occurs, so that only an elongation that actually corresponds to a reduction in thickness takes place. Excessive rolling in the width direction of the strip causes the strip to curve within this width direction, thereby impairing the flatness of the strip, while reaching a zone where too little thickness reduction occurs. In this case, the strip will be under tension. To obtain a flat strip, it is therefore necessary to roll the strip in such a way that it is not subjected to tension after it leaves the last roll stand.

To create a uniformly spaced roll gap, the rolls must be crowned so that under the rolling action a flat roll gap defined by parallel generating lines results. However, such crowning can only compensate for certain rolling load conditions. The additional bending of the rolls also only makes it possible to modify the rolls in order to adapt them to certain symmetrical rolling load gradients. Therefore, in order to achieve a sufficiently tension-free state during rolling of aluminum sheets, automatic thermal crown control is proposed in ASEA magazine AV83-102T (October 1971 issue). In this crown control, a measuring roller is provided as a detection element, which detects the tension occurring in each zone behind the roll stand of the strip, which measuring roller is in each zone in order to apply lubricating or cooling liquid. It acts via a control device on control valves provided in front of all provided nozzles. "Archiv fur Eisenhuettenwesen" first made public in May 1972
Regarding the above, Separate Print C No. 931 states that in order to eliminate flatness irregularities, the intended thermal changes in the roll diameter and therefore also the intended thermal changes in the roll gap at such flatness irregular positions are He says it can be observed. Possible treatments to address this change are changes in coolant volume, pressure and temperature. During cold rolling of wide strips, three- or five-band cooling is often used for this purpose. Very fine-grained cooling is common for rolled aluminum materials.

However, applying the experience gained in aluminum rolling to strips of other metals, especially steel, is fraught with various difficulties. This means that in order to achieve a long service life of the roll surface as well as to obtain a satisfactory strip surface, a minimum amount of lubrication is required. In many cases, for example when rolling relatively hard strips,
Certain requirements are met on coolant temperature and lubricant temperature. Moreover, zone-wise heating treatments of the roll carried out for the same purpose tell those skilled in the art regarding the realization of a given thermal crown that such a thermal change in diameter can only be achieved over a long period of time. Gave me experience. Federal Republic of Germany Patent Publication no.
2908641 from Aluminum Rolling Mill - Technology also suggests that by mixing coolants of two different temperatures a large temperature difference between the liquid and the rolls, i.e. a large thermal transition, can be achieved. However, it was not accepted by experts. If the theory disclosed in this publication is followed, the consumption of liquid with a significant cooling effect is relatively high and the control valve with mixing valve has high manufacturing and maintenance costs.

In the present invention, the idea established in the known art as mentioned above, namely, by changing the temperature of the rolling oil or coolant sprayed, i.e. by applying different temperatures, the roll adjustment time is shortened. Based on the well-known theory that it is possible to roll a strip by holding the strip to be rolled under no tension in a roll stand for rolling the strip, i.e., to curve the strip. The object of the present invention is to provide a method and device for rolling a strip without causing any problems or impairing the flatness of the strip, and for this purpose, rolling can be carried out while reducing manufacturing costs and maintenance costs of the device and reducing work labor. It makes it possible to reach short control times for and is also applicable under all working conditions of cold rolling roll stands used in the steel industry. It is an object of the present invention to provide a method in the manner described at the outset and a device for implementing this method.

The above problems are solved by the present invention as follows. That is, at least an amount of liquid is applied at a first temperature to a roll stand provided on the side of the measuring position where at least a partial tension measurement is carried out, with the spray width adjusted to ensure lubrication between the rolls. and supplying at least the work roll with a controllable amount of liquid corresponding to the other zones at a second lower temperature.

Furthermore, the apparatus according to the present invention is characterized by the following points. That is, the roll is provided with cooling beams, and the nozzles of these cooling beams are arranged so that liquid can be supplied to the nozzles of these cooling beams in a controlled manner via a valve from a first reservoir containing liquid at a first temperature. and at least one other cooling beam is provided for each work roll, these nozzles being able to be supplied with cold liquid via a control valve arranged behind the control device according to the zone. This problem can be solved by configuring it as follows.

In the present invention, the crown of the roll within the control value detection band, the bending of the roll under rolling load, and the increase in roll diameter under temperature conditions are
Used as a parameter to check tension distribution.

In order to achieve optimal rolling of the strip, the strip must have equal longitudinal tension in all width areas. For this purpose, the rolling force must be controlled. The tension of the strips in individual, mutually parallel bands is then measured, and the results are used as control values for the control device.

In the above configuration, it is possible to predetermine the basic amount of liquid required in any case, thus ensuring a perfect basic cooling as well as completely sufficient lubrication, and also It is advantageous that an optimal action of this cleaning liquid is also guaranteed when applied. In particular, it is possible to carry out an optimum temperature adjustment for the basic lubrication, basic cooling and basic quantities of cleaning liquid in such a way that the liquids can be supplied, and that this temperature adjustment is accompanied by an optimum lubrication effect,
For example, the viscosity, droplet size, etc. can be adjusted, as can the optimum cleaning properties. Effective cooling is only additionally provided. The consumption of liquid with a strong cooling effect is therefore reduced to a minimum. Furthermore, the configuration of the device can be relatively simple. This is because there is no need for expensive mixing valves, and instead simple control valves or very simple check valves can be used.

Other characteristic configurations of the present invention are described in claims 2 to 5 and 7 to 20.

The invention will be explained in more detail below with reference to embodiments illustrated in the accompanying drawings.

In FIG. 1, a cold-rolled steel strip 1 is shown schematically and partially cut away. This cold-rolled strip is passed between work rolls 2 and 3 supported by back-up rolls 4 and 5 of a four-layer cold-roll stand (not shown). The cold strip 1 that comes out runs around the circumference of the strip tension-measuring roller 6 at a small winding angle. This strip tension measuring roller makes it possible to detect the strip tensions in jacket zones that are successive in the respective axial direction. The measured values obtained are derived via a slip ring system 7.

The rolls 2-5 are provided with cooling beams 8-13. These cooling beams are equipped with nozzles to eject liquid. The arrangement dimensions of these nozzles are adapted to the zone distribution dimensions of the strip tension measuring roller 6. In this example the cooling beam is
It has two nozzles every 52 mm, which can be supplied with liquid together and separately from the other nozzle. In this case, cooling beams 8 and 9
belongs to Backup Prora 4 and 5. These cooling beams are provided with a constant flow of liquid with adjustable width and intensity to achieve a predetermined base lubrication and base cooling through the nozzles. Similarly, the cooling beams 10 and 11 of the work rolls 2 and 3 are provided with liquid with adjustable width and intensity. The cooling beams 12 and 13, which are provided in front of the roll gap at a relatively large angle,
A liquid is provided at a lower temperature than that provided to the cooling beams 8-11. Its strength is adjusted depending on the tension detected for that zone so that the difference in tension within different zones approaches zero.

The supply of liquid to the nozzle will be explained in detail below using the block diagram shown in FIG.

The supply of liquid takes place in the embodiment shown in FIG. 2 from two separate reservoirs 14 and 15. These and one of the storage parts should be at the temperature normally used, e.g. 45°C.
, while the reservoir 15 contains the liquid of the container 1
Contains a liquid whose temperature is lower than that of liquid No. 4. For example, the temperature inside the storage section 15 is 25°C.
The reservoir is filled with refluxing liquid in the usual manner.
In this case, depending on the circumstances, filling of the reservoir 15 can take place from the reservoir 14 via a cooler.

The liquid supply to the cooling beam takes place via intermediate pumps 16 and 17 located behind the reservoirs 14 and 15. The feed strength of these relay pumps can be adjusted depending on the consumption by pressure limiting valves 18 and 19 located downstream. Behind these pressure limiting valves there are filters 20 and 21 which, if blocked, are bypassed by the pressure valves. Cooler 2 in the area of relay pump 17
2 is additionally shown. This cooler can optionally provide additional cooling.

A large number of valves 23 connected in parallel are provided in front of the relay pump 16. This number of valves corresponds to the number of regions of cooling beams 8-11. In the drawing, only the first two valves and the last valve of the valves 23 are shown. The liquid supply to the corresponding front zones of the cooling beams 8 to 11 takes place in parallel. However, if necessary, e.g. valve 23
double the number of cooling beams 8 and 9 and 10 and 1
It is possible to carry out the feeding parallel to one corresponding zone or to quadruple the number of fractions, and to hold each of the mutually corresponding zones of the cooling beam individually adjustable. If the plate width is selected and the band is 31, then 31, 62 or 124 valves 2
3 will be provided.

The liquid provided by the relay pump 17 is supplied to a group of similar control valves 24 which supply liquid to the zones of the cooling beams 12 and 13, respectively. Again, in this example, depending on the number of bands selected,
Thirty-one valves are provided, of which only the two outermost valves are shown in the drawing; the valves shown on the right are located in the corresponding outer zone of the cooling beams 12 and 13. The liquid is supplied parallel to the In this case too, it is possible to control the corresponding zones of the cooling beam individually by doubling the number of control valves.

A strip tension measuring roller 6 is used as a detection element for the control device 26. The detection system of the individual band - 31 in the exemplary embodiment - is connected via a measuring line 25 to the corresponding input of the control device 26 . The outputs of the individual control units of the control device act via lines 27 on control valves 24 provided as control elements. A constant value control can be provided to achieve a fast and effective control process. However, from the signals of the detection system of each band, an average value is formed as a guidance value for sequence control, and by this, the difference in partial strip tension within the band is set to zero, that is, this average value. It is advantageous to control on the basis of When configuring the individual control members, the detection part is not located within the roll stand itself, but rather
Care must be taken to ensure that it is placed 1000-2000mm behind the roll gap. If this arrangement is not used, this control section will have temperature inertia -
This is done by using a low temperature liquid.
In addition to this, the position of the roll on which the liquid is sprayed is moved into the roll gap, and the cold temperature when the roll is removed from the roll gap is affected. It becomes difficult to recognize the progress of the movement of the rolled strip to the tension measuring roller 6. In particular, if the selected temperature differences are relatively large, the control characteristic curve is constructed in such a way that control fluctuations are avoided.

By using a lower temperature second liquid, the present invention makes it possible to achieve effective thermal crown control that acts relatively quickly and thus allows for the balancing of short-term tension fluctuations. In this case, it is an advantage that both the control device and the valve for controlling the additional liquid as regulating element have a relatively simple construction, thus making possible a cost-effective device. It would also be advantageous to use a display device provided in a customary manner for the lateral tension distribution of the strip, but this has not been shown in this embodiment for reasons of clarity. Furthermore, the control can also be carried out by manual adjustment of the valve 23 or by hand. Therefore, it is not only possible to adapt the basic cooling to the particular working pattern, but also to shut off the nozzles that are located outside the width of the strip to be rolled in each case, and on the other hand to The nozzle can be operated in such a way that an advantageous thermal adjustment of the crown also takes place in the transition region to the roll jacket which is not under rolling load. Furthermore, in the case of a six-layer roll stand, for example, by blocking the zones, it is possible to ensure that when the rolls are moved axially, the liquid spray takes place temporarily on the sides of the roll end faces or in the attachment area of the rolls. You can avoid being exposed. Furthermore, basic lubrication can be carried out at temperatures that are found to be advantageous. This is because the viscosity of the emulsified oil can be optimally adjusted, as can the size of the droplets in the emulsifier. Also, vegetable or animal fats and oils can be used at appropriate temperatures. When using a cleaning liquid, the temperature can be adjusted to achieve the optimum cleaning effect and thus sufficient utilization of the cleaning liquid. Basic lubrication and basic cleaning are only secondary effects on the respective rolling temperature. Rather, they are determined by the regular addition of cold liquid. In this case, by taking advantage of the high temperature difference, it is possible to perform the work with a relatively small amount of additional relatively cold liquid;
Therefore, the working costs are also lower.

The device selected in the preferred embodiment can be varied in many ways. That is, for example, as already mentioned, by providing individual valves in front of the nozzles of one zone of the cooling beam and configuring the device in such a way that different cooling beams do not have to work in parallel in the same zone. be able to. A liquid supply of simple construction and easy to maintain can be achieved by providing the cooling beam with one or more liquid connections working in parallel and with valves.
It can be constructed by being carried by a cooling beam - just in front of the nozzle. In this case, these liquid connections may be partially or completely integrated into the cooling beam. The strong flow fluctuations and associated pressure fluctuations that occur when opening and closing the valve can be avoided by installing an additional pressure control valve at a short distance or via a short conduit in front of the valve, or by reducing the pressure as shown in Figure 2. It can be reduced by providing the control valve 18 or 19 immediately before the valve 23 or the control valve 24. The pressure fluctuations occurring during the opening/closing process can be further reduced by using the valve 23 or the control valve 24.
In front of the pressure reservoir 3 is maintained via a short conduit and accordingly a liquid mass which can be slightly accelerated.
This can be achieved by providing 0 or 31.

For reasons of facilitating liquid reflux, the liquid is contained in one of the reservoirs, for example reservoir 14, and is heated to a specified temperature in a cooler provided in front of this reservoir or contained within this reservoir. Brought to high working temperature. Especially if, unlike the configuration shown in FIG. 2, a cooler is provided in front of the pressure control valve, low-temperature liquid can be obtained with a simple cooler. However, it is advantageous to transfer the liquid used at low temperatures from the storage tank 14 into the storage tank 15, in which case the necessary further cooling is provided by an intermediate cooler and/or by an integrated cooler in this storage tank. This can be done by means of a cooler, and it is advantageous to place the cooler in front of the pressure control valve, but in some cases, according to FIG. It is advantageous for a constant liquid flow to have a pronounced cooling behavior.

In some cases, it is also possible to similarly control a roll stand provided in front of the roll stand to be controlled, and it is advantageous to provide a cooling beam that regularly sprays the work rolls of this roll stand with a low-temperature liquid. It is. In this case, a flat behavior of the control characteristic curve, i.e. the respective occurring liquid flow differences are small and/or the liquid is supplied at a temperature between the first and second temperatures. Therefore, it is possible to provide a relatively large distance from the measuring roller.

A simple control and a particularly simple, therefore hassle-free and inexpensive construction of the control valve make it possible to operate the control without analog control and on the on-off or three-point control principle (consisting of three contacts, three It is a control device that operates on a value.It is also applied, for example, when controlling a three-phase AC heating winding.In this case, three quantities are regulated by a three-contact switch: the heating winding is switched off, the heating winding is switched off, This is possible if the heating windings are connected in a star pattern (low capacity heating power) and the heating windings are connected in a delta (high capacity heating power). . For example, if the liquid flow of the individual nozzles is controlled by pulses, this fluid flow can be varied in such a way that the connection times and/or connection time intervals are controlled and different cooling effects are achieved. On the other hand, it is possible to control the base flow in a suitable manner and to generate additionally strong liquid flow pulses from the point at which a limit value at which the base cooling is constant is exceeded.
Due to the different opening and closing times of the individual controls, the effects of flow fluctuations can be kept relatively small. In order to adequately balance the flow fluctuations, a pressure control valve and/or a pressure reservoir can be provided immediately before the valve 23 and/or the control valve 24, as already mentioned.

To form a value for the control device, an average value of the individual band measurements is also determined, which can be used as a reference value for the control element. However, the reference value may be arbitrarily set in advance or may be formed from the reel tension. It is only important that the tensions occurring in the individual zones are adjusted to a common average value so that no tensions occur which deform the strip after the tensioning by the reel has ended.

In all these cases, effective thermal control of the roll crown is achieved at low production costs and, with this, rolling without tension in the strip;
It is therefore possible to roll flat strips. In addition, the basic lubrication or cleaning does not take place within a temperature range that is considered unfavorable for its function, so that the strip is not damaged.

[Brief explanation of drawings]

FIG. 1 is a schematic representation of the rolls of a four-layer roll stand with an associated cooling beam and a front-mounted strip tension measuring roll; FIG. 2 is a block diagram showing the arrangement of a liquid supply section to the cooling beam. The symbols in the figure are 2 to 5... Roll, 3, 4... Work roll, 6... Measuring roll, 8 to 11... Cooling beam, 12, 13... Second cooling beam, 1
4...Storage tank, 24...Control valve, 26...Control device.

Claims (1)

Claims: 1. A quantity of liquid which performs a cooling, lubricating and/or cleaning action in dependence on the local tension detected in a zone existing in the direction transverse to the strip in front of the last roll stand; This is done by thermotechnically adjusting the diameter of the roll by spraying this liquid onto the roll by varying the pressure or temperature and controlling the temperature distribution in the axial direction of the roll, keeping the strip tension-free. In the rolling method, at least an amount of liquid is applied to a roll stand provided in front of the measuring position where at least partial tension measurement is performed by adjusting the spray width to ensure lubrication between the rolls. and supplying at least the work rolls 2, 3 with a controllable amount of another liquid corresponding to the zone at a second lower temperature. How to hold and roll. 2. A method according to claim 1, characterized in that the control is carried out in an analog manner. 3. A method according to claim 1, characterized in that the pulsed starting phase is carried out under on-off control. 4. Any one of claims 1 to 3, characterized in that the spraying is performed on rolls 2 to 5 of at least the last roll stand of the rolling line on the exit side of the strip. Method described. 5. The controllable spraying of the low-temperature liquid according to the zone takes place at an angular distance from the roll gap that is greater than the spacing of the region to which the first relatively high-temperature liquid is supplied. The method described in any one of the ranges 1 to 4. 6. At least one roll stand, with a nozzle arranged in the cooling beam, which can spray the rolls of this roll stand with a liquid and which acts on a control device with a valve as a regulating member, In an apparatus for rolling a strip under no tension, in which a detection unit for detecting strip tension in the region of the cold strip is provided in front of the roll stand, cooling beams 8 to 8 are applied to the rolls 2 to 5. 11 are provided, and the nozzles of these cooling beams are arranged so that liquid can be supplied to the nozzles of these cooling beams in a controlled manner via a valve 23 from a first reservoir 14 containing liquid at a first temperature; and at least one other cooling beam 12, 13 on the work rolls 3, 4 respectively.
The strip plate is characterized in that it is configured such that low-temperature liquid can be supplied to these nozzles through a control valve 24 provided at the rear of a control device 26 according to the zone. A device for holding and rolling without tension. 7. The distribution according to the zone of the nozzles of the cooling beams 10 and 11 corresponds to the distribution according to the zone of the nozzles of the cooling beams 12 and 13,
Apparatus according to claim 6. 8. The device according to claim 6 or 7, characterized in that the cooling beams 8 to 13 of the last roll stand in the rolling direction of the strip are provided on the entry side of this roll stand. . 9 Cooling beam 12,1 where low temperature liquid is sprayed
3 is provided at a larger angular distance from the roll gap formed between the work rolls 2, 3 than the angular distance from the roll gap of the cooling beams 10, 11 capable of spraying high temperature liquid. An apparatus according to any one of claims 6 to 8. 10. Claim 6, characterized in that two or three cooling beams 12, 13 are provided respectively for low temperature liquid whose flow rate can be controlled by the work rolls 2, 3. 9. The device according to any one of clauses 9 to 9. 11. Any one of the preceding claims 6 to 10, characterized in that the valve 23 and/or the control valve 24 are provided on and/or within the cooling beams 8-13. The device described in one of the following. 12. The control unit according to any one of claims 6 to 11, characterized in that the control unit of the control device 26 is configured to operate according to on-off control or three-point control principle. Device. 13. The pressure control valve 18, 19 is provided in front of the valve 23 or the control valve 24 at a small interval, as described in any one of claims 6 to 12 above. equipment. 14 Pressure reservoir 3 in valve 23 or control valve 24
0.31 is provided via a short conduit on the entry side.
Apparatus according to any one of paragraphs 1 to 13. 15. Claims 6 to 14, characterized in that a liquid reflux is absorbed from the reservoir 14 and a liquid cooled to a low temperature is taken out from this reflux. A device according to any one of the above. 16. The device according to claim 15 or 16, characterized in that the removed liquid is guided through a cooler. 17. characterized in that the removed liquid is guided through the second storage section 15;
An apparatus according to claim 15 or 16. 18. Device according to claim 17, characterized in that the reservoir 15 has a cooling device. 19 The work roll of the penultimate roll stand of the roll stands provided in front of the detection unit 6 for detecting the tension in the strip also has at least one cooling beam for controllably spraying a low-temperature liquid. Claim 6 is characterized in that:
Apparatus according to any one of paragraphs 1 to 18. 20 Liquid control in cooling the work rolls of the roll stand is performed with a control characteristic curve that is flatter than the control characteristic curve for the work rolls 2 and 3 provided immediately in front of the detection unit 6, and/
20. The device according to claim 19, characterized in that it is configured to operate with or with significant damping.