Regulating a rolling process

Abstract

A method and a regulating device for regulating a rolling process, wherein a rolling material is rolled in a rolling gap between two working rollers of a rolling stand. A target forward slip value (f.sub.s) for a forward slip (f) of the rolling material is specified, and an actual forward slip value (f.sub.M) of the forward slip (f) of the rolling material is ascertained. The forward slip (f) of the rolling material is regulated to the target forward slip value (f.sub.s) in that a lubricant rate (u.sub.R) of a lubricant is applied to the rolling material and/or at least one working roller depending on the actual forward slip value (f.sub.M) and the target forward slip value (f.sub.s).

Claims

1. A method for regulating a rolling process in which a rolling material is rolled in a rolling gap between two working rolls of a rolling stand, comprising: specifying a target forward slip value for a forward slip of the rolling material; determining an actual forward slip value of the forward slip of the rolling material; forming, in a control path, a control variable based directly on the actual forward slip value and the target forward slip value; and applying a lubricant at a lubricant rate to at least one of the rolling material and at least one working roll based on the control variable to regulate the forward slip of the rolling material to the target forward slip value.

2. The method as claimed in claim 1, further comprising: measuring an exit speed of the rolling material downstream of the rolling stand, determining a roll speed of a roll surface of a working roll, and determining the actual forward slip value from the exit speed and the roll speed.

3. The method as claimed in claim 1, wherein 0.05 is specified as the target forward slip value.

4. The method as claimed in claim 1, wherein a hysteresis interval is specified for the forward slip, and the lubricant rate is changed only if the actual forward slip value deviates from the hysteresis interval.

5. The method as claimed in claim 4, wherein an upper limit of the hysteresis interval is 0.03 higher than the target forward slip value.

6. The method as claimed in claim 4, wherein a lower limit of the hysteresis interval coincides with the target forward slip value.

7. The method as claimed in claim 1, further comprising: determining a friction coefficient of a friction between the rolling material and a working roll, and applying the lubricant based also on the friction coefficient.

8. The method as claimed in claim 1, further comprising: determining a rolling force acting on the rolling material in the rolling gap, and applying the lubricant based also on the rolling force.

9. The method as claimed in claim 1, wherein, for the application of the lubricant, a mixture of the lubricant and a carrier gas is produced and sprayed at least one of onto at least one working roll and into the rolling gap.

10. The method as claimed in claim 1, wherein, for the application of the lubricant, a rolling emulsion containing the lubricant is produced and applied to at least one of the rolling material and at least one working roll.

11. The method as claimed in claim 1, wherein, for the application of the lubricant, the lubricant is applied in pure form to the rolling material upstream of the rolling gap and at a distance from the rolling gap.

12. A regulating device for carrying out the method as claimed in claim 1, comprising: a forward slip determination device determining the actual forward slip value of the forward slip of the rolling material; a lubricant dispensing device, which is set up to dispense the lubricant at least one of onto the rolling material and onto at least one working roll; and a regulating unit, which is set up to regulate the forward slip of the rolling material to the target forward slip value by setting the lubricant rate of the lubricant dispensed by the lubricant dispensing device in accordance with the actual forward slip value and the target forward slip value.

13. The regulating device as claimed in claim 12, wherein the forward slip determination device is set up to measure an exit speed of the rolling material downstream of the rolling stand and to determine a roll speed of a roll surface of a working roll.

14. The regulating device as claimed in claim 12, wherein the lubricant dispensing device is set up to produce at least one of: a mixture of lubricant and a carrier gas and to spray the mixture at least one of: onto at least one working roll; and into the rolling gap; and a pure lubricant dispensed onto the rolling material at a distance upstream of the rolling gap.

15. The method as claimed in claim 1, wherein the forming of the control variable is performed without accessing a model.

16. The method as claimed in claim 2, wherein the exit speed of the rolling material is measured by a strip tension measuring roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above-described properties, features and advantages of this invention and the manner in which these are achieved will become more clearly and distinctly comprehensible in conjunction with the following description of illustrative embodiments, which are explained in greater detail in conjunction with the drawings. In this case:

(2) FIG. 1 shows schematically a rolling stand, a rolling material and a lubricant dispensing device,

(3) FIG. 2 shows a diagram of a rolling material speed as a function of a rolling material position, and

(4) FIG. 3 shows a block diagram of a control loop for regulating a rolling process.

DETAILED DESCRIPTION

(5) FIG. 1 shows schematically a rolling stand 1 by means of which a rolling material 3 is rolled, and a lubricant dispensing device 5 for dispensing a lubricant.

(6) The rolling stand 1 has two working rolls 7, which are spaced apart by a rolling gap 9. The rolling material 3 is in the form of a metallic rolled strip, which is passed through the rolling gap 9 in a rolling direction 11. During the rolling of the rolling material 3, the two working rolls 7 rotate at angular speeds of the same magnitude but mutually opposite directions, with the result that their roll surfaces 13 have a roll speed v.sub.N, the direction of which corresponds to the rolling direction 11 at the location of the rolling gap 9.

(7) By means of the lubricant dispensing device 5, it is possible, for example, to produce a mixture of lubricant and a carrier gas and to spray it onto the working rolls 7 and/or into the rolling gap 9. For this purpose, the lubricant dispensing device 5 has, for example, an atomization device, in which the mixture can be produced, and a plurality of spray nozzles, by means of which the mixture can be dispensed.

(8) As an alternative or in addition, the lubricant dispensing device 5 can be used, for example, to produce a rolling emulsion containing lubricant and to dispense it onto the rolling material 3 and/or onto the working rolls 7.

(9) Moreover, the lubricant dispensing device 5 can alternatively or additionally be used to dispense pure lubricant onto the rolling material 3 upstream of the rolling gap 9 and at a distance from the rolling gap 9, for example.

(10) By means of the lubricant dispensed using the lubricant dispensing device 5, the rolling process is regulated in the manner described in greater detail below with reference to FIG. 3.

(11) FIG. 2 shows a diagram of a rolling material speed v of the rolling material 3 as a function of a rolling material position x in the region of the rolling gap 9. At an entry position x.sub.0 upstream of the rolling gap 9, the rolling material 3 has an entry speed v.sub.0. In the rolling direction 11, the rolling material speed v increases in the region of the rolling gap 9 until it reaches an exit speed v.sub.1 at an exit position x.sub.1 downstream of the rolling gap 9. Between the entry position x.sub.0 and the exit position x.sub.1, the rolling material speed v adopts the value of the roll speed v.sub.N of the roll surfaces 13 of the working rolls 7 at a no-slip position x.sub.N defining the neutral point.

(12) FIG. 3 shows a block diagram of a control loop for regulating the rolling process in which the rolling material 3 is rolled in the rolling gap 9 between the working rolls 7 of the rolling stand 1. The rolling process is regulated by means of a regulating device which comprises a forward slip determination device 15, the lubricant dispensing device 5 and a regulating unit 17. The regulating unit 17 is the controller of the control loop, the lubricant dispensing device 5 is the actuator of the control loop, the forward slip determination device 15 is the measuring element of the control loop, and the rolling stand 1 and the rolling material 3 form the control path 19 of the control loop.

(13) The control variable of the control loop is the forward slip f of the rolling material 3, which, according to equation [1], is formed from the exit speed v.sub.1 and the roll speed v.sub.N. FIG. 2 shows that the forward slip f is a measure of the position of the neutral point. The closer the neutral point is to the exit position x.sub.1, the smaller is the forward slip f. The forward slip f is therefore particularly suitable as a control variable for regulating the position of the neutral point.

(14) To regulate the rolling process, a desired forward slip value f.sub.s, to which the forward slip f is regulated, is specified. Approximately 0.05 is specified as the desired forward slip value f.sub.s, for example.

(15) The forward slip determination device 15 is used to determine an actual forward slip value f.sub.M of the forward slip f. For this purpose, the forward slip determination device 15 is set up to measure the exit speed v.sub.1 of the rolling material 3 downstream of the rolling gap 9 and to determine the roll speed v.sub.N. The exit speed v.sub.1 is measured, for example, by means of at least one strip tension measuring roller, which is arranged downstream of the rolling stand 1 and rolls on a rolling material surface of the rolling material 3. As an alternative, the exit speed v.sub.1 is measured optically, e.g. by means of laser measurement. The roll speed v.sub.N of a working roll 7 is determined from the angular speed and radius of the working roll 7, for example, wherein the angular speed is determined from a rotational speed of a motor driving the working roll 7, for example.

(16) From the desired forward slip value f.sub.s and the actual forward slip value f.sub.M, a control deviation is formed by subtracting the actual forward slip value f.sub.M from the desired forward slip value f.sub.s. The regulating unit 17 forms a control variable u dependent on the control deviation, and said variable is applied to the lubricant dispensing device 5. The lubricant dispensing device 5 outputs, as a manipulated variable of the control loop, a lubricant rate u.sub.R of the lubricant, which is dependent on the control variable u, wherein the lubricant rate u.sub.R denotes a lubricant quantity per unit time. For example, a hysteresis interval is specified for the forward slip f, and the lubricant rate u.sub.R is changed only if the actual forward slip value f.sub.M deviates from the hysteresis interval. For example, a hysteresis interval is specified, the upper limit of which is approximately 0.03 greater than the desired forward slip value f.sub.s and the lower limit of which coincides with the actual forward slip value f.sub.M.

(17) In a further development of the method, described with reference to FIG. 3, for regulating the rolling process, the lubricant rate u.sub.R is additionally set in accordance with at least one further parameter of the rolling process. For example, a friction coefficient of a friction between the rolling material 3 and a working roll 7 is determined as a further parameter, and the lubricant rate u.sub.R is also set in accordance with the friction coefficient. As an alternative or in addition, a rolling force acting on the rolling material 3 in the rolling gap 9 is determined as a further parameter, for example, and the lubricant rate u.sub.R is also set in accordance with the rolling force. In this case, the friction coefficient and/or the rolling force are determined in real time from current process variables of the rolling process by means of a rolling gap model, for example.

(18) Although the invention has been illustrated and described more specifically in detail by means of preferred illustrative embodiments, the invention is not restricted by the examples disclosed, and other variations can be derived therefrom by a person skilled in the art without exceeding the scope of protection of the invention.

LIST OF REFERENCE SIGNS

(19) 1 rolling stand 3 rolling material 5 lubricant dispensing device 7 working roll 9 rolling gap 11 rolling direction 13 roll surface 15 forward slip determination device 17 regulating unit 19 control path f forward slip f.sub.M actual forward slip value f.sub.s desired forward slip value v rolling material speed v.sub.0 entry speed v.sub.1 exit speed v.sub.N roll speed u control variable u.sub.R lubricant rate x rolling material position x.sub.0 entry position x.sub.1 exit position x.sub.N no-slip position