US3889505A

US3889505A - Process and an apparatus for regulating the drive or deceleration of power driven or decelerated rollers in drawing and straightening installations

Info

Publication number: US3889505A
Application number: US436920A
Authority: US
Inventors: Josef Ihle
Original assignee: Individual
Current assignee: UNGERER IRMA
Priority date: 1973-02-07
Filing date: 1974-01-28
Publication date: 1975-06-17
Anticipated expiration: 1992-06-17
Also published as: BE810710A; SE400532B; FR2216816A5; IT998950B; AT324804B; DE2305777C3; DE2305777A1; DE2305777B2; GB1440987A

Abstract

What follows is a description of a process and apparatus for regulating the drive or deceleration of power driven or decelerated rollers in installations in which a strip of material is passed across a plurality of rollers under a stretching tension. In effecting this regulation, the variation in elongation to which the strip is subjected during its passage across a roller is measured and them compared with a preset nominal value. The comparison is then utilized for regulating the roller drive.

Description

0 United States Patent 1 1 1111 3,889,505 Ihle June 17, 1975 1 1 PROCESS AND AN APPARATUS FOR 2.519.818 8/1950 Blain 72/2411 x REGULATING THE DRIVE on 2,526,296 10/1950 Stone .1 72/205 $559,431 2 1971 Noe et a1. 72/21 DECELERATION OF POWER EN 0R 3,783,667 1/1974 Munchbach 1. 72/205 DECELERATED ROLLERS IN DRAWING AND STRAIGHTENING INSTALLATIONS lnventor:

Foreign Application Priority Data Feb. 7, 1973 Germany 2305777 US. Cl. 72/17; 72/19; 72/205 Int. Cl B2lb 37/06; B2lb 39/08 Field of Search 72/8, 9 l9. 17. 205, 249

References Cited UNITED STATES PATENTS 11/1943 Hume .1 72/9 Primary Examiner-Milton S. Mehr Attorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT What follows is a description of a process and apparatus for regulating the drive or deceleration of power driven or decelerated rollers in installations in which a strip of material is passed across a plurality of rollers under a stretching tension. In effecting this regulation. the variation in elongation to which the strip is subjected during its passage across a roller is measured and them compared with a preset nominal value. The comparison is then utilized for regulating the roller drive.

6 Claims, 2 Drawing Figures PATENTEDJUN 17 I975 SHEET FQE PATENTEDJUN17 1915 11869505 SHEET 2 I PROCESS AND AN APPARATUS FOR REGULATING THE DRIVE OR DECELERATION OF POWER DRIVEN OR DECELERATED ROLLERS IN DRAWING AND STRAIGHTENING INSTALLATIONS BACKGROUND OF THE INVENTION The present invention relates to a process and apparatus for regulating the power drive or deceleration of rollers in installations in which a strip of material, preferably a metal strip, is passed under stretching tension across a plurality of rollers; and more particularly in drawing and straightening installations.

In drawing and straightening installations, a metal strip is stretched between a hold-back frame provided with a braked roller and a drawing frame provided with a power driven roller. This braking can be considered as a negative power drive. The drawing force must first be applied to that section of the strip to be stretched as an additional drawing force and must then be removed from the strip via the driven rollers as it leaves this section.

According to the rope formula (S -S 'e P a the drawing or pulling forces acting on the end of the feed section and the beginning of the delivery section of a strip being supplied across a roller differ by the factor e a If, for example. in drawing and straightening installations it is desired to make the difference between the strip drawing forces on the feed side and on the delivery side of the strip as great as possible with a minimum number of rollers, the friction value between the rollers and the strip must be advantageously ex ploited; while sliding of the strip on the rollers must be avoided. Sliding not only occurs when the friction force between the roller and the strip is exceeded, but also when a longer strip section per unit of time is supplied to a roller driven at a constant rate of revolution that corresponds to the distance covered by the circumference of the roller in this time. The length of the section of strip supplied per unit of time can be increased, for example, through a permanent elongation imparted to the strip during its passage over preceding rollers.

In the case of drawing and straightening installations, it is known to adapt the circumferential speed of the rollers disposed in S-frames to the alteration of the length of the section of strip, for example, by varying the diameter of the rollers being driven in common and at the same rate of rotation, or by driving rollers of the same diameter by means of individual regulatable electomotors. It is also known to provide differential gearing between rollers of the same diameter driven by an electromotor, or in installations comprising rollers of the same diameter, to incorporate release clutches or electromagnetic slip clutches between these and stepdown gears. For example, in German Offenlegungsschrift Pat. No. 2,] 18,051 there is disclosed the use of differential gearing, the output rotational speed of which is designed to be varied via the compensating gear supports by a regulating gear according to the nec essary increase or decrease in the rotational speed.

Some of the known installations are expensive and some are difficult to adapt especially during operation of the installation to the operating conditions which may vary according to the strip to be processed.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to obviate these difficulties and to provide a process and an apparatus for effecting this process which, without being expensive, enables regulation according to measured values while the apparatus is in operation.

This and other objects are accomplished according to the present invention in that in a process of the type mentioned initially, the elongation variation to which the strip is subjected as it passes across a roller is measured, electrically compared to preset nominal values, and the result of the comparison used to electrically influence the drive or deceleration of at least this one roller.

A development of the present invention, therefore, consists in that the elongation variations are examined in the form of differences in the speed of the end section of the strip on the delivery side of the roller in relation to the speed of the end section of the strip on the feed side of the roller. And then instead of the speed of the strip section on the feed side of the roller, the circumferential speed of the roller and the speed of the section of strip being delivered by the roller are measured and the measurements converted into electrical impulses and transmitted in this form. During operation, should the circumferential speed ofthe roller and the speed of the strip section on the feed side of the roller no longer correspond. a greater sensitivity of the difference readings will result from taking the circumferential speed of the roller as a basis.

With this in mind, an apparatus for effecting the process according to the present invention is characterized in that the circumferential speed of the roller and the delivery section of the strip are measured by means of measuring wheels which drive function generators supplying electrical impulses, the number of which is proportional to the rate of rotation of the roller. A compan ator is provided which determines the variations of the predetermined values and the predetermined difference in the rate of rotation as a measurement of the variation in elongation. In addition, an auxiliary drive means is provided and is adapted to be controlled by this comparator and designed to drive electric regulating devices for influencing the power drive or deceleration means of the rollers.

A development of the apparatus according to the present invention consists in that the looping angle at which the strip engages the roller is made larger by a reserve amount than would be necessary given an average coefficient of friction and slip-free operation in order to maintain a specific desired difference between the drawing forces acting on the end section of the strip on the feed side of the roller and the section of the strip on the delivery side of the roller. In this way, even if the friction value is reduced for some reason, for example, owing to soiling or to the use of a different strip material which produces a smaller friction value on the material on the circumference of the roller, the differences in the drawing tension and thus the drawing forces remain unchanged without any slipping occurring.

Advantageously, the presetting device for the nominal value and the comparators for indicating the preset values and the values determined (nominal value actual value comparators) give the indications in numeri cal form. The possibility of reading the values continuously facilitates operation.

The following results were obtained by means of the present invention: without adversely affecting the cooperation between the roller and the strip, the friction value between them may be fully exploited; the circumferential speeds of the individual rollers and their torques may be regulated over a wide range. and. be cause nominal values which may be preset are proceeded from. diameter variations resulting from wear of the rollers or the influences of differences in the na ture of the strip material as expressed. for example, by different elasticity moduli. may easily be taken into account.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagram illustrating a two roller hold-back frame of a drawing and straightening installation according to the present invention.

FIG. 2 is a block diagram according to the present invention related to a roller of a drawing and straightening installation.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a strip 3 is looped about rollers l and 2 in an S-shaped manner. The circumferential speed of the roller 1 which is equal to the speed of the section of strip 3 which is being supplied to this roller is measured by means of a measuring wheel 19, while the speed of the strip section being delivered by the roller I is measured by means of the measuring wheel 20. The circumferential speed of the roller 2 is measured by means of the measuring wheel 21, while the speed of the strip section being delivered by the roller 2 is measured by means of a measuring wheel 22. The measuring wheels are in driving connection with

function generators

24, 25, 26 and 27. The function generators transmit a very large number of electrical impulses per rotation of the wheels. The strip 3 is looped about the roller I at a looping angle a, and the roller 2 at a looping angle (1 The roller 1 rotates in the direction of the arrow 4 in FIG. I, that is, in a clockwise direction. The roller 2 rotates in the direction of the arrow 5 in FIG. 1, thus in a counterclockwise direction. The drawing force S] acts on the end of the strip section on the feed side of the roller 1, while the drawing force S2 acts on that portion of the strip section passing between the

rollers

1 and 2, that is, that portion which is being delivered by the roller 1 and supplied to the roller 2. The drawing force S3 acts on the strip section being delivered by the roller 2. Tensile stresses 0'] to 0'3 correspond to the drawing forces S1 to S3. On the circumference of the roller 1, the drawing force S1 increases by an amount Z1 to S2. On the circumference of the roller 2, the drawing force 82 increases by an amount Z2 to S3. To render them more apparent, in FIG. 1, the forces and auxiliary forces which are actually acting on the strip 3 in its particular direction of movement have been indicated in an outwardly directed position radial to the circumference of the rollers. Specific elongation quantities correspond to the individual drawing forces. The elongation of a unit length of the strip thus in creases with the drawing forces and with the tensile stresses corresponding thereto. The drawing forces S1 S3 correspond to elongations 61 to 3 per unit length of the strip. The elastic elongations e per unit length of the strip and the tensile stresses 0' in the strip are related by the modulus of elasticity E according to the equation 6 0'/E. Thus, 6 ol/E and c 02/E. If Ae, represents the increase in the elongation e, in the are of the strip looped about the roller 1, A6, 5 e, (0- 0' l/E. If the difference 0 0', corresponding to the auxiliary force Z. is designated as 0-,, with a strip cross section F, o =Z/F. If the length of the strip on the circumferential arc ofthe roller 1 corresponding to the loop angle a is 1,, the increase in this length is AI|,:AE\ I 0 I|IE=Z| If the ratio of loads is selected in such a way that S, S e a no sliding is produced even as the friction value becomes smaller. Thus, a reserve is obtained within which the reductions in the friction value. for example, by soiling or temperature variations, are rendered harmless. To make this apparent in the diagram of FIG. 1, a minimum angle B, or B is indicated for which 5-; S, e a so that the reserve angles 7, and v representing the above-mentioned reserve are provided over and above the actual looping angles a, and a As is apparent from the diagram represented in FIG. 1 showing two rollers, the same relationships apply for each successive roller. In as far as drawing and straightening installations are concerned, the same mathematical interrelationships apply to rollers of multi-roller drawing frames as for rollers of multi roller hold-back frames. As, however, apart from the creep which occurs owing to the variation in the elongation of the strip on the looped roller arc on account of the difference In the strip drawing forces on both sides of a roller, it is necessary to operate below the sliding limit, only the reserve region represented by the reserve angles y, and in FIG. 1 is available for regulating the rates of rotation and/or the retaining or drawing torques of the rollers. Accordingly, it is absolutely essential for this re serve region to be provided.

According to FIG. 2, the roller 1 is connected to a regulatable direct current motor 31 via gearing 28, stepdown gearing 29 and a motor coupling 30. A nomi nal value presetting device 32, which is connected to a nominal-actual value comparator 34, is engaged at a predetermined value corresponding to a specific increase in elongation A6,. The desired regulating sensitivity is engaged by means of a regulatorprecision adjustment device 33. The function generator 24 driven by the measuring wheel 19 transmits to the nominalactual value comparator 34 the information in the form of electric impulses regarding the circumferential speed of the roller 1 which, as long as no slipping occurs, is equal to the speed of the strip 3 corresponding to the elongation 6,. In the same manner, the function generator 25 driven by the measuring wheel 20 running on the strip 3 transmits to the nominalactual value comparator 34 the data including the actual increase in elongation A6,.

The difference between the number of impulses transmitted by the function generator 24 and the function generator 25 gives the actual value of A5, which is compared in the comparator 34 with the nominal value which has been supplied to the nominal value preset ting device 32. The direct current motor is regulated according to the result of the comparison in the comparator 34 via a current regulator 35 and an output step 36 in such a manner that the actual value balances out the predetermined nominal value with the regulating precision with which the regulator-precision adjustment device has been provided.

In devices comprising compound drives, the electromagnetic slip couplings. servomotors or regulating gears for regulating the rates of rotation and/or torques of individual rollers via differentials during the mechanical shunt, can be controlled in the same manner.

What is claimed is:

l. A process for regulating the drive or deceleration of power driven or decelerated rollers in installations in which a strip of material, preferably a metal strip, is passed across a plurality of rollers under a stretching tension, more particularly in drawing and straightening installations, comprising the steps of: measuring the variation in elongation to which the strip is subjected during its passage across a single roller; electrically comparing the variation in elongation with preset nominal values; and utilizing the result of the comparison for the electrical influencing of the power drive or deceleration of at least this one roller.

2. A process according to claim 1, wherein the elongation variations are determined by measuring the differences in the speed of the section of strip of material leaving the roller from the speed of the section of strip of material being supplied to the roller.

3. A process according to claim 1, wherein the elongation variations are determined by measuring the differences in the circumferential speed of the roller and the speed of the section of strip of material leaving the roller and wherein the utilization of the comparison results in converting the compared differences into electrical impulses for transmission.

4. An apparatus for regulating the drive or deceleration of power driven or decelerated rollers in installations in which a strip of material, preferably a metal strip, is passed across a plurality of rollers under a stretching tension, more particularly in drawing and straightening installations, comprising for each roller: measuring wheels operatively associated with the roller for respectively measuring the circumferential speed of the roller and the section of strip of material leaving the roller; a function generator connected to each wheel, each said function generator supplying electrical impulses, the number of which is proportional to the number of revolutions of the wheel; a nominal valuepresetting device for establishing a predetermined value; a comparator receiving the electrical impulses for determining the difference between the measurement of the circumferential speed of the roller and the section of strip of material leaving the roller and comparing this difference to the predetermined value; and roller drive means receiving the comparator output for regulating the drive of said drive means.

5. A device according to claim 4, wherein the strip of material defines a loop angle in its engagement with each roller, said angle being selected so that it is greater than is necessary by a reserve amount with a given friction value and with slip-free operation occurring between the strip of material and the roller, and wherein because of the reserve amount a specific desired difference between the drawing forces on the section of strip of material approaching the roller and the section of strip of material leaving the roller is maintained.

6. A device according to claim 4, wherein the nominal value-presetting device and the nominal-actual value comparator provide their information in numerical form.

Claims

1. A process for regulating the drive or deceleration of power driven or decelerated rollers in installations in which a strip of material, preferably a metal strip, is passed across a plurality of rollers under a stretching tension, more particularly in drawing and straightening installations, comprising the steps of: measuring the variation in elongation to which the strip is Subjected during its passage across a single roller; electrically comparing the variation in elongation with preset nominal values; and utilizing the result of the comparison for the electrical influencing of the power drive or deceleration of at least this one roller.

4. An apparatus for regulating the drive or deceleration of power driven or decelerated rollers in installations in which a strip of material, preferably a metal strip, is passed across a plurality of rollers under a stretching tension, more particularly in drawing and straightening installations, comprising for each roller: measuring wheels operatively associated with the roller for respectively measuring the circumferential speed of the roller and the section of strip of material leaving the roller; a function generator connected to each wheel, each said function generator supplying electrical impulses, the number of which is proportional to the number of revolutions of the wheel; a nominal value-presetting device for establishing a predetermined value; a comparator receiving the electrical impulses for determining the difference between the measurement of the circumferential speed of the roller and the section of strip of material leaving the roller and comparing this difference to the predetermined value; and roller drive means receiving the comparator output for regulating the drive of said drive means.