Method and device for winding a metal strip

Abstract

The invention relates to a method for winding a metal strip (1) into a reel with a winding mandrel (2), to which the metal strip (1) is routed through a pair consisting of a first and a second driver roller (5, 6), at least one of which is driven. The method is characterized in that a difference between the strip speed (V.sub.B) of the metal strip (1) and the speed) (v5, v6) of the driver rollers is adjusted on the basis of measuring, from measurable process variables, the strip speed and the speed (v5, v6) of at least one of the driver rollers (5, 6).

Claims

1. A method of winding a metal strip (2) on a reel having a mandrel to which the metal strip (2) is routed by a pair of first and second driver rollers (3, 4) of which at least one is driven, wherein a difference between a strip speed (V.sub.B) of the metal strip (2) and a speed of the driver rollers is adjusted based on measurement of the strip speed and the speed (Vu, Vo) of at least one of the driver rollers (3, 4) from measurable process variables, wherein a controller (22) so controls the difference between the strip speed (V.sub.B) of the metal strip (2) and the speed of at least one of the driver rollers (3, 4) that the difference between the strip speed (V.sub.B) and a surface or circumferential speed (V.sub.u, V.sub.o) of the driver rollers (3, 4) does not exceed an adjustable threshold, characterized in that a drive torque of the at least one driver roller (3,4) is so predetermined that the difference between the strip speed (V.sub.B) and the surface speed (V.sub.u, V.sub.o) of the at least one driver roller (3, 4) does not exceed the adjustable threshold, in that drives of the driver rollers (3, 4) and the mandrel (1) are controlled by controlling a contact force of the driver rollers (3, 4) applied to the strip (2), and the set rotational speeds of the drives are so predetermined that a predetermined relative speed (AVset) between the driver rollers (3, 4) is maintained, and in that the set value of the contact force of the driver rollers (3, 4) is so controlled that a predetermined tension in the metal strip (2) takes effect in a region between the driver rollers (3, 4) and a coil wound on the mandrel (1).

2. A method according to claim 1, characterized in that a contact force of at least one driver roller (3,4) applied to the strip (2) is so predetermined that the difference between the strip speed (V.sub.B) and the surface speed (V.sub.u, V.sub.o) of the at least one driver roller (3, 4) does not exceed the adjustable threshold.

3. A method according to claim 1, characterized in that a rotational speed of the mandrel is controlled.

4. A method according to claim 1, characterized in that a drive torque of the mandrel (1) is so predetermined that the difference between the strip speed (V.sub.B) and the surface speed (V.sub.u, V.sub.o) of the at least one of the driver rollers (3, 4) does not exceed the adjustable threshold.

5. A method according to claim 1, characterized in that the strip speed (V.sub.B) is measured in a contactless manner by sensors (9, 9a) or by a speed measuring roller (10) that applies pressure to the metal strip (2), or that the strip speed (V.sub.B) is determined by measuring a rotational speed of the mandrel (1) and a diameter of strip windings wound on the mandrel (1) or the coil (12).

Description

(1) Below, an exemplary embodiment will be described in detail. The drawings show:

(2) FIG. 1 a schematic side view of a winding device for winding a metal strip on a mandrel with a driver having two driver rollers;

(3) FIG. 2 a schematic plan view of the driver rollers and the mandrel together with respective drives;

(4) FIG. 3 a control diagram for calculation of speeds of the driver rollers and the mandrel; and

(5) FIG. 4 tension control and the control diagram of the contact forces of the driver rollers.

(6) A winding device (FIG. 1) serves for winding a metal strip 2 that is wound to a coil 12 of the metal strip 2. The metal strip 2 reaches the winding device on a horizontal roller table where it is deflected to the mandrel 1 by two driver rollers 3, 4 which are leaning against the metal strip 2 and against each other, and is wound there in a coil 12.

(7) The driver rollers 3, 4 provide the metal strip 2 with the necessary tension. The driver rollers 3, 4 and the mandrel 1 are driven, respectively, by a motor 7, 8 or 19, directly or, alternatively, via a gear set. In one embodiment of the invention, only one of the driver rollers 3, 4 is driven, whereas another driver roller 3, 4 is carried along. Preferably, the torques of the driver rollers 3, 4 or the mandrel 1 are regulated. The rotational speeds of the motors 8 and 19 (FIG. 2) are measured by rotational speed sensors 13, 14 or 20.

(8) The motors 7, 8, 19 are operated with a speed regulation. For each drive, a rotational speed regulator 71, 81, 191 (FIG. 3) determines a torque set value dependent on a set rotational speed, an actual rotational speed, and time-dependent run of both signals, which is communicated to an associated converter 72, 82, or 192 that regulates the motor current. The converters 72, 82, 192 provide a present (momentary) value of the torque. In the drawings, the converters 72, 82, 192 are shown with thyristor symbols because the converters 72, 82, 192 can include switching means that, preferably, have a thyristor.

(9) The object of the process consists in driving the driver rollers 3, 4 with a lower speed than the strip speed V.sub.B that is predetermined by the drive of the mandrel 1, so that a predetermined relative speed between the driver rollers 3, 4 and the strip 2 is obtained. To this end, the circumferential speeds V.sub.u,V.sub.o of the driver rollers 3, 4 and the coil 12, which are calculated taking into account the motor rotational speeds K.sub.1, K.sub.2, K.sub.3, possible gear ratios, drive characteristics such as slip, friction, etc., and diameters of the driver rollers 3, 4, and the radius of the coil, are considered. The coil radius can be calculated based on the changing and metrologically determined diameter of the mandrel which is determined based on the number of windings which are counted during the winding process, and the strip thickness. Alternatively, it is also possible to directly measure the coil radius with a distance measuring apparatus 11.

(10) The strip speed V.sub.B can also be measured with a contactless sensor 9, 9a that can be arranged between the driver rollers 3, 4 and the mandrel 1 or in front of the driver rollers 3, 4. It is also possible to use a contact measuring roller 10 insertable between the driver rollers 3, 4 on one hand, and the coil 12, on the other hand, for measuring the strip speed V.sub.B.

(11) A high-level control system (FIG. 3) provides set values for the strip speed V.sub.B set and the relative speed V.sub.A set between the driver rollers 3, 4, on one hand, and the strip 2, on the other hand.

(12) A force generating device for pressing the driver rollers 3, 4 against the metal strip 2 can, as shown, by the way of example, with respect to the driver roller 4 in FIG. 1, be formed as hydraulic cylinders 5, 6. The hydraulic cylinders 5, 6 act on the journals of the driver roller 4 on both sides, adjacent to the drive side AS and on opposite side, operational side BS. The force actual values are determined from measurement of acting in hydraulic cylinders, pressures 15, 16 or 17, 18, wherein the pressures from 15 to 18 are determined from measurement values obtained on the annular surface A ring or on the piston side surface A piston, as shown in FIG. 2 with respect to the hydraulic cylinder 5.

(13) The forces on both sides are regulated independent from each other. The set forces are determined from a basic value Fset, possible correction values F.sub.AS, F.sub.BS, of controllers or other regulation systems, and a force correction for providing a predetermined tension.

(14) In order to determine the force correction necessary for obtaining a desired strip tension, firstly, an actual value for the tension Zact in the strip 2 in the region between the driver rollers 3, 4 and the coil 12 is calculated by a calculator unit 21, taking into consideration possible operational factors, momentary coil radius, friction losses, effect of acceleration, and deformation stress of the strip material at bending around the mandrel.

(15) The force correction F for the contact force of the driver rollers 3, 4 is determined, based on the difference between the predetermined set value Z.sub.set for the strip tension and the calculated actual value Z.sub.act as well as its time-dependent run, by, e.g., a proportional integral controller 22 (FIG. 4), and is communicated, together with the set value of the force, to an adder the output value of which on both sides, the drive side AS and the operational side BS, is combined by a further adder with correction values F.sub.AS, F.sub.BS, and is communicated to the respective force regulator 23, 24 as force set value. Those are obtained from comparison of the actual force values F.sub.AS, F.sub.BS which are obtained from measured pressures, with force set values for the values of the force generating devices in form of the hydraulic cylinders 5, 6 on the drive and operational sides. The controllers can be formed as three-point controllers for timely changes of the force correction.

(16) The circumferential speed V.sub.o of the upper roller 4 is obtained from the diameter d.sub.4 of the roller 4 and the rotational speed signal N14 of the drive of this roller measured in revolution/min from an equation:
vo=n.sub.14d.sub.4/60;
and for the lower roller 3 having a diameter d.sub.3 and rotational speed .sub.13, from an equation:
v.sub.u=n.sub.13d.sub.13/60.

(17) The circumferential speed V.sub.B of the coil 12 with a changing coil radius .sub.B and the rotational speed of the driver and which is measured in revolution/min, is determined from an equation:
V.sub.B=n.sub.12r.sub.B/30.

(18) The coil radius an be calculated from the mandrel diameter d.sub.D, the number of windings n.sub.w, and the strip thickness h as follows:
r.sub.B=d.sub.D+nwh.

(19) The actual values F.sub.AS and F.sub.BS in the cylinders can be calculated based on the measured pressures and the hydraulic operational surfaces on the piston side and the annular side of the respective piston. For the drive side AS, this value is:
F.sub.AS=A.sub.pistonP.sub.17A.sub.ringP.sub.18;
for the operational side BS, this value is
F.sub.BS=A.sub.pistonP.sub.15A.sub.ringP.sub.16.

LIST OF REFERENCE NUMERALS

(20) 1 Mandrel

(21) 2 Strip

(22) 3 Lower driver roller

(23) 4 Upper driver roller

(24) 5 Force generating device on the drive side

(25) 6 Force generating device on the operational side

(26) 7 Upper roller drive

(27) 8 Lower roller drive

(28) 9 Sensor for sensing the strip speed

(29) 9a Sensor for sensing the strip speed

(30) 10 Speed measuring roller

(31) 11 Sensor for sensing the coil diameter

(32) 12 Coil

(33) 13 Tachometer of the lower roller

(34) 14 Tachometer of the upper roller

(35) 15 Pressure sensor of cylinder 5, piston side pressure

(36) 16 Pressure sensor of cylinder 5, ring side pressure

(37) 17 Pressure sensor of cylinder 5, piston side pressure

(38) 18 Pressure sensor of cylinder 5, ring side pressure

(39) 19 Mandrel drive

(40) 20 Mandrel rotational speed sensor

(41) 21 Calculator unit for calculation of the actual traction between the driver and the coil

(42) 22 Controller of strip tension between the driver and the coil

(43) 23 Force controller

(44) 71 Force controller

(45) 72 Rotational speed controller

(46) 81 Rotational speed controller

(47) 82 Converter

(48) 191 Rotational speed controller

(49) 192 Converter