US2539540A

US2539540A - Regulating mechanism for winding rolled material

Info

Publication number: US2539540A
Application number: US583322A
Authority: US
Inventors: Idar Karl Henrik; Lindahl Gunnar
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1944-03-20
Filing date: 1945-03-17
Publication date: 1951-01-30
Anticipated expiration: 1968-01-30

Description

Jan. 30, 1951 K. H. [DAR ET AL 2,539,540

REGULATING MECHANISM FOR WINDING ROLLED MATERIAL Filed March 17, 1945 2 Sheets-Sheet 1 INVENTORE Jan. 30, 1951 K. H. lDAR Er AL 2,539,540

REGULATING MECHANISM FOR WINDING ROLLED MATERIAL Filed March 17, 1945 2 Sheets-Sheet 2 Patented Jan. 30, 1951 REGULATING MECHANISM FOR WINDING ROLLED MATERIAL Karl Henrik Idar and Gunnar LindahL' Vasteras,

Sweden, assignors to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Application March 17, 1945, Serial No. 583,322 In Sweden March 20, 1944 3 Claims.

In rolling strips and especially in cold rolling it is for several reasons desired that the strip during the rolling is exposed to a pull either only in the part of the strip leaving the rolling mill or also in the entering part. By this pull the capacity of the rolling mill will be larger but above all a better product is achieved. It is, however, very important that the pull is even and constant and regulable in wide A regulation of the rolling mill in dependence of the pull in the material can be achieved in a plurality of ways. So may for instance the reels be movable on rails or may be swinging supported, and in both cases actuated by a force tending to pull them in the direction from the mill. The motion of the reel will then bev a measure on the pull and can be used for regulating of the pull to a constant value. This arrangement is, however, combined with mechanical disadvantages and the design of it will be complicated and expensive. A pure electrical regulation of the pull by regulation of the driving motors of the reels is also possible but this arrangement will not give a sufllcient accuracy during the periods of acceleration and retardation.

The present invention has for its object a method of regulating the pull in the rolling mill, which is simple and not combined witlr the mentioned disadvantages.

According to the invention the driving aggregate for the reels is supported on the shaft of the reel so that it can perform a swinging motion around it, which motion is counteracted by a stationary member taking up the reactive torque from the driving aggregate. This member may for instance be a spring attached to the foundation, in which the size of the swinging motion will be a direct measure of the torque, but other ways of measuring the torque may also be imagined, for instance a stationary pressure box, containing a member sensitive to the pressure, for instance a resistance or a piezo-electrical crystal, which will give a voltage proportional to the pressure. The principle is that the reactive torque from the driving aggregate is translated to an electric magnitude, which then can be used for the regulation.

If a constant pull in the material is desired, a regulation of the torque exerted on the reel from the driving aggregate will not be sufficient, because the diameter of the reel will change during the rolling operation. When the reel acts on the material coming from the mill exerting a Pull in the material, the diameter of the reel will increase when material is wound on it, and if the material is already wound on the reel, it will decrease in diameter when during operation the material is unwound from it. In the latter case, the reel acts as a brake on the material entering the mill. In order to get a constant pull in the material, it is therefore necessary'that in the regulation the changes of the diameter of the reel is taken into consideration, i. e. the torque oi. the driving aggregate must be changed inversely proportional to the diameter of the reel. Thus if M is the torque exerted on the reel from the driving aggregate, the value of must be regulated to a constant value, F being the pull'in the material and r: the radius of the reel.

According to the invention, the changes of the diameter of the reel can be taken into consideration in two difierent ways either directly as shown in the,arrangement according to Fig. 1 or indirectly by means of the excitation current of the motor driving the reel driving aggregate, as shown in Fig. 2.

According to the invention, the voltage impressed on an excitation or regulation winding in a generator exciting the reel driving aggregate motor is made directly proportionally dependent on one hand upon the deflection of the driving aggregate due to variations of the torque exerted by it and on the other hand inversely proportionally dependent upon the diameter of the reel, as stated in the preceding paragraph, the said generator further having a field winding, the control winding, fed with a constant current which can be set to a desired value, and a field winding connected in parallel with its armature.

Such generators are commonly used in many regulating devices and act so that if they are so arranged that their armature currents have an influence uponthe voltage impressed upon the regulating field winding over some system to be regulated by the generator, the current from the exciter is changed until the ampere turns of the regulating field winding become equal to the ampere turns of the control winding.

As stated above, Fig. 1 shows an arrangement, in which the reel diameter has an influence upon the regulation by means of a member directly measuring the diameter, whereas Fig. 2 shows an arrangement, in which the reel diameter indirectly over the field current of the driving aggregate motor has an influence upon the regulation.

In Fig. l, I designates the rolling mill and 2 a pulling reel, which is supposed to be driven by means of a tooth gear 8 supported on the shaft of the reel. This gear is coupled with a driving motor 4 built together with the gear. The gear is balanced by a spring 22 between the gear housing and the foundation. The motor 4 is fed from a generator 5 and the field I of the motor 4 is fed in series with a constant voltage current source from a generator 8 having three field windings, of which one is a separately fed control winding I8, one is a regulating winding II connected to a potentiometer I2, the contact arm of which being actuated by the driving aggregate and one is a shunt winding 9 connected to the brushes on the armature of the generator 8. The generator 5 as well as the generator 8 is driven by a three phase motor I4. The winding III is connected to a potentiometer 6, which in its turn is connected to a constant voltage. By this potentiometer a desired voltage can be impressed upon the winding III.

The potentiometer I2 is in series with a regulable resistance I3 connected with a constant volt- 1 tage current source not shown on the drawing. The sliding contact of the resistance I3 is attached to a. lever I5 having aroller I6 rolling on the surface of the material wound on the reel 2.

The mill I is supposed to be driven by a motor 28 in such a way that the surface speed of the material becomes constant, but any other convenient prime mover may be employed.

The action of the arrangement is most readily described if it first is assumed that the resistance I3 in series with the potentiometer I2 has a constant value. When the diameter of the reel increases, the torque of the driving aggregate has a tendency to increase. The contact arm of the potentiometer I2 will then move upwards, so that the voltage on winding II increases and thus the current through it. The alternation of the voltage of the generator 8 will then increase the current through the winding I. When the current through the winding I increases, the armature current of the motor 4 will decrease so that the torque of the aggregate will decrease until the contact arm on potentiometer I2 has moved back to the position giving ampere turns through winding II equal to that of winding I 0. This is due to the fact that with increasing field current through the motor 4 the induced voltage in it increases and that the armature current must decrease.

A given setting of the current through winding I0 means therefore a constant torque from the driving aggregate.

A constant torque means, however, when the diameter of the reel increases a decreasing pull in the material. Now a constant pull is desired and this means that the torque from the driving aggregate must increase with increasing diameter of the reel. This is achieved thereby that the voltage on the potentiometer I2 is caused to vary inversely with the changes of the diameter. This is accomplished by means of the resistance I3 and contact arm I5. When the diameter increases, a larger part of resistance I3 is inserted in series with the potentiometer I2 and thus the smaller becomes the current through the potentiometer I2. A larger diameter of the reel thus means at a given current through the winding II correspondent to a given current through the winding III a higher position of the contact arm on potentiometer I2 and thus a higher'torque from the driving aggregate. As a sum of the whole: The current through the winding II is changed proportionally to the torque and inversely proportional to the diameter of the reel and as this current must be constant, the ratio M/d remains constant and thus also the pull.

The arrangement according to Fig. 2 differs from the preceding in that the resistance I3 and lever I5 is dispensed with and instead the wind- 8' II is fed from a generator l8 excited from a winding I9 in series with the. field winding 1, which generator is driven from a motor I] excited from the potentiometer I2. A motor 23 driving the mill I may be connected to the generator 5.

This arrangement acts in the following way: When'the reel 2 increases, this on the first hand will cause a decrease of the speed of the motor 4. The torque exerted by it will have a tendency to increase and the gear housing swings, so that a lower voltage is taken out from the potentiometer I2. The motor I! and thus also the generator I8 will then run with a higher speed and thus its voltage becomes higher and so also the current through the winding II. As the winding II counteracts the windings 9 and ID, the magnetization of the latter being adjustable by a resistance 2|, the corresponding alternation of the voltage of the generator 8 then will increase the current through the windings I and 9. This increase results in an increased induced voltage in the motor 4 with a corresponding decrease of its armature current and thus of its torque until the gear housing 3 has returned to a position in which the ampere turns of the winding II again have been equal to the ampere turns of the winding I0. This position will thus be a function of the position of the gear housing and of the current through the winding I9. An increase of the diameter of the roll will thus result in a corresponding increase of the current through the field winding I, and as the surface speed of the strip is constant, the said current is inversely proportional to the revolutions of the reel and thus to the diameter of it.

We claim as our invention:

1. In a rolling mill for strips or wires, a driving motor for the mill, a reel for the material to be rolled. a driving aggregate for the reel comprising a gear supported by the shaft of the reel and a motor attached to the gear housing, a member yieldingly opposing the motions of the ear housing under the influence of torque variations in the reel shaft, a generator for the driving aggregate motor having three field windings, of which one is connected in parallel with the armature, one is separately fed from a constant voltage current source and one is fed with a voltage proportional to the deflection of the driving gear and inversely proportional to the diameter of the reel.

2. In a rolling mill for strips or wires, a driving motor for the mill, a reel for the material to be rolled, a driving aggregate for the reel comprising a gear supported by the shaft of the reel and a motor attached to the gear housing, a member yieldingly opposing the motions of the gear housing under the influence of torque variations in the reel shaft, a contact attached to the gear housing sliding over a potentiometer resistance, a regulable resistance inserted in series with said potentiometer resistance, a sliding contact on said regulable resistance attached to a lever in contact with the surface of the material on the reel, a generator having three field windings, of

which one is connected in parallel with the armature, one is separately fed from a regulable voltage source and one is fed from the potentiometer resistance, the armature of said generator in counter-connection to a constant voltage source being connected to the field of the driving aggregate motor.

3. In a rolling mill for strips or wires, a driving motor for the mill, a reel for the material to be rolled, a driving aggregate for the reel comprising a gear supported by the shaft of the reel and a motor attached to the gear housing, a member yielding opposing the motions of the gear housing under the influence of torque variations in the reel shaft, a contact attached to the gear housing sliding over a potentiometer resistance, a motor excited from the said potentiometer, an exciter coupled to the shaft of said motor, a gen- REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Country Date Great Britain July 22, 1935 Number I