US3839888A

US3839888A - Tension levelling of strip

Info

Publication number: US3839888A
Application number: US00304182A
Authority: US
Inventors: J Greenberger
Original assignee: Wean United Inc
Current assignee: Wean United Inc
Priority date: 1972-11-06
Filing date: 1972-11-06
Publication date: 1974-10-08
Anticipated expiration: 1991-10-08
Also published as: FR2205379A1; GB1447781A; FR2205379B3; CA974868A

Abstract

The disclosure of the invention pertains to a method and apparatus for producing flat rolled steel strip by tension levelling. The unflat strip is subject to varying tensions by a pair of tension bridles. Between the bridles are arranged two sets of nested, flexing and/or rolling rolls and on the entry and delivery sides of the roll sets are arranged strip deflecting rolls which are both skewable and mechanically shapeable to vary the unit tension of the strip during its flexing and/or rolling. Also on the entry and delivery sides of the sets of flexing rolls are strip shape detecting rolls which are associated with a computer control unit that produces both feed forward and/or feed backward control signals for varying the total tension, the flexing and/or rolling, and the unit tension to give the most ideal processing conditions for a strip of given characteristics.

Description

Greenberger 1 1 1974 [5 1 TENSION LEVELUNG 0F STRHP 3,605,470 9/1971 Polakowski 72/163 [75] Inventor: $1 2223? lgaGreenberger Primary Examiner-Milton S. Mehr Attorney, Agent, or Firm-Henry C. Westin; Daniel [73] Assignee: Wean United Inc., Pittsburgh, Pa. Pat h 22 Filed: Nov. 6 1972 1 s [57 ABSTRACT [2]] Appl' 3047182 The disclosure of the invention pertains to a method and apparatus for producing flat rolled steel strip by [52] 11.3. (I1 72/17, 72/205, 72/161 tension levelling. The unflat strip is subject to varying [511 lint. C1 821d 1/02 tensions by a pair of tension bridlles. Between the bri- [58] Field of Search 72/ 160, 165, 205, 17 dles are arranged two sets of nested, flexing and/or rolling rolls and on the entry and delivery sides of the [56] References Cited roll sets are arranged strip deflecting rolls which are UNITED STATES PATENTS both skewable and mechanically shapeable to vary the s unit tension of the strip during its flexing and/or roll- ?82125? 3/132; 831E321?""""'iiiiiiiijijijf'ii 3 215 Also on she ssssy sss sslivssy sides sf shs ssss sf 332531445 5/1966 Franeku... 72/205 x flexing rolls are Strip Shape detecting 10115 which are 3,324,695 6/1967 Sirilotti 72/ 15 associated with a computer control unit that produces 3,326.026 6/1967 Guillot i v. 72/163 both feed forward and/or feed backward control sig- 3,328,992 7/1967 Stone i 72/250 X nals for varying the total tension, the flexing and/or 311374343 9 y 72/205 rolling, and the unit tension to give the most ideal pro- 3s459s0l9 3/1969 Stone s s s cessing conditions for a strip of given characteristics 3,499,306 3/1970 Pearson i 72/17 3,527,078 9/1970 Lawson et al 72/160 21 Claims, 4 Drawing Figures 2a a: a0

TENSION LlEVELLING OF STRIP Though many different attempts have been made in the past in the metal industry to produce flat strip in an economical high production manner only partial success has been achieved. One of the reasons for this failure has been the fact that the characteristics of the strip, such as thickness, physical properties, and metallurgy vary considerably not only from strip to strip but within a given strip itself.

While tension levelling employing nested flexing rolls has been suggested in the past their success as best has only been rudimental, because on the one hand the work capable of being performed was not sufficient to meet the varying conditions, and on the other hand the procedures of controlling the working forces was very uncoordinated and ineffectual.

It is therefore an object of the present invention to provide a method and/or apparatus for producing flat metallic strip that will overcome among others the enumerated disadvantages and limitations of prior practices.

More particularly the present invention provides a method and apparatus for producing flat metallic strip at an efficient and high production rate including the steps and apparatus of subjecting the strip to a substantial total tension but below its yield point, causing the strip while under said tension condition to pass between a series of strip flexing rolls where the strip is additionally subjected to reverse flexing sufficient to impart a relatively small amount of permanent elongation to the strip, varying the unit tension transversely of the strip in a manner to vary the transverse unit tension of the portion of the strip being subject to the flexing operation, determining the transverse flatness profile of the strip and changing at least one of said total tension, flexing or unit tension operations to reduce nonflatness in the strip.

These objects and other novel features and advantages of the present invention will be better appreciated when the following description of a preferred embodiment thereof is read along with the accompanying drawings of which:

FIG. I is an elevational view, partly in section, of an arrangement of equipment for practicing the present invention,

FIG. 2 is a plan view of FIG. I

FIG. 3 is a schematic enlarged elevational view, partly in section, of some of the equipment illustrated in FIG. 1 and wherein the strip flexing units are shown in their rolling and flexing positions and FIG. 4 is a partial view of one of the strip flexing units illustrated in FIG. 3 shown in a strip flexing position.

In referring to FIGS. I and 2 a rolled carbon steel strip is shown, the two arrows indicating the entrance and delivery of the strip to a tension levelling zone of a strip processing line. At the entrance and delivery cnds of the zone there are arranged identical strip tension bridle units 12 and I4 each having a entry set of horizontally spaced-apart driven rolls l6 and 18 from where the strip 10 passes to a delivery set of similar driven

rolls

20 and 22. The

rolls

18 and 20 cooperate with pinch rolls 24 which are vertically adjusted by piston cylinder assemblies 26. Bridle units of the type illustrated are well known in the steel strip producing industry so that the details of their functions and operations are not deemed necessary. Sufficient is to note that they are employed, by virtue of a speed differential and the wrap angle between the cooperative sets of rolls 16-18 and 2022, to subject the strip I0 to substantial total tension up to the yield point of the strip, and that the total tension is variable by changing the power furnished to the roll sets. In the case of mild carbon rolled steel strip 48 inches wide and having a thickness of 0. 125 inch a desirable overall operating tension would be of the order of 60,000 lbs. total tension.

Between the entry roll set 20 and 22 and the delivery roll set 16%8 two sets of flexing or flexing and rolling rolls are provided, the entry set being identified at 28 and the delivery set at 30, both of which are rotatably supported in a common housing 32.

Roll set 28 comprises an upper quickly adjustable backup roll 34 which engages a smaller diameter nested roll 36, the lower surface of which engages one surface of the strip while the opposite surface of the strip is engaged by two

larger diameter rolls

38 and 40. As best shown in FIGS. 3 and 4- the backup roll 34 which is carried at each of its opposite ends by a bearing chock assembly 42 is vertically positioned against motor operated screw stops 44 associated with each chock assembly, by virtue of piston cylinder assembly one being shown at 46, which is shown only in FIGS. I and 2. The screw stops 44 and piston cylinder assemblies 46 permit the nested smaller roll 36 to vary its penetration into the space between the

rolls

38 and 40 from a rolling condition where the strip is both flexed and compressed by rolling between the

rolls

36 and 38 and 40 to only a pure flexing action where the roll 36 is spaced from and out of direct contact with the

rolls

38 and 40. FIG. 3 is meant to portray the flexing and rolling condition where the total permanent elongation imparted by these forces will not exceed 2 to 4 percent while FIG. 4 portrays the pure flexing condition where the total .permanent elongation will be less than 2 percent. A desirable roll size range for various carbon steels will find the large rolls 34., 38 and 40 being of a diameter between 12 to 14 inches and the small nested roll 36 having a diameter of between 3 to 6 inches.

The rolls of the flexing or flexing and rolling set 30 are identical but inverted with respect to the roll set 28, in which as shown in FIG. 3 the upper larger rolls 4% and 50 are vertically positioned by piston cylinder assemblies 52 against motor operated screw stops 54 for the purpose already explained with respect to the roll set 23.

On the entry and delivery sides of the roll set 28 and 30 there are arranged transversely of the path of the strip

strip engaging rolls

56 and 58 rotatably sup,- ported in the housing 32. The roll 56 is arranged to engage the upper surface of the strip while the roll 53 en gages the lower surface. As shown by the legends and arrows in FIG. 3 the

rolls

56 and 58 are vertically tiltable and which is indicated in legend in FIG. 3 as ROLL TILTING. The rolls are also mechanically shaped to change the crown which is legend ME- CHANICAL ROLL SHAPING and/or to have their ends moved in a horizontal plane whis is legend SKEW- ING in FIG. 3. The result of tilting, mechanical shaping and skewing, as is well known in the art, is to vary the unit tension of the strip in the roll bite of the

roll units

28 and 30. In other words in changing the crown of

rolls

56 and 58 and/or its end to end position, in which the roll is rotated about its minor axis, a greater or less unit tension can be brought into play transversely of the strip as it is being worked in the

roll set units

28 and 30, by virtue of varying the lengths of the paths of travel of different portions of the strip width. Since the use of strip deflecting rolls in which the crown of the rolls may be varied by outboard bending forces or skewing or tilting end to end by power means are well known details of construction need not be given.

Also mounted in the housing 32 at its extreme outer ends are rolls 60 and 62 which are identified by the leg ends SHAPE DETECTING appearing in FIG. 3 and which are provided to detect the transverse flatness profile of the strip passing to and from the

roll flexing units

28 and 30. There are several well known types of such measuring devices in the industry such as that illustrated and described in US. Pat. Nos. 3,481,194 dated Dec. 2, 1969 and 3,499,306 dated Mar. 10, 1970, among others not as well publicized. The basic purpose of these units is to determine the transverse strip profile, i.e., both the magnitude and location of the hills and valleys of non-flatness. Arranged between the rolls 5660 and 58-62 are strip deflecting rolls 63 provided to assure proper contact between the rolls 56-60 and 5862.

As noted before an important aspect of the invention is to provide a method and means that will enable the best possible individual or collective usage of the several corrective forces developed by the

units

12, 14,, 28, 30, 56, and 58 in removing or reducing the non-flatness from the strip as determined by either or both of the

shape detectors

60 and 62. With this in mind these corrective forces are correlated and varied with reference to a given condition of the strip by a master control computer 64. The control receives signals from the

detector rolls

60 and 62 of the non-flatness of the strip and issues command signals to one or more of the

units

12, 14, 28, 3t), 56 and 58 as is determined to be neces- 'sary to correct totally or in part for the particular nonflat condition of the strip. The computer control 64 will follow the typecustomarily provided in the steel industry for strip processing equipment, in which as shown in FIG. 2 the control receives signals from the shape detector rolls 60 and 62 from signal generating units 66 and 68 respectively, along with signals of tension values from the tension bridles l2 and 14 by

signal units

70 and 72 and pressure signals from the

piston cylinder assemblies

46 and 52. It then employs this data to obtain the best coordinated use of the equipment in removing totally or in part the non-flatness from the strip.

In briefly describing the operation of the above explained equipment and control let it be assumed as suggested by FIG. 1 that a strip is being fed through the bridleunits 12 and 14 as it is being processed. While the equipment can be operated in a number of different ways, such as by a feed forward and/or a feed backward control system, semi-automatic or fully automatic, a fully automatic feed forward and feed backward system will be described.

As shown in FIG. 1 as the strip passes over the shape detecting roll 60, the signal generator 66 will issue a feed forward signal to the control unit 64 and cause the effective working forces produced by entry units i.e., the bridle 12, deflector roll 56 and the flexing and rolling unit 28 to vary if necessary to give the ideal combination of total tension, roll crowning and/or skewing or tilting and mechanical shaping and flex-ing and/or rolling required. As the strip 10, passes over the delivery shape detecting roll 62 should there still exist any nonflatness a vernier or trim correction will be initiated by a feed backwards signal from the signal units 68 to the control 64. The control then will initiate a trim control signal to one or more of the

delivery units

30, 58 or E4 to still further reduce or eliminate any non-flatness in the strip. The control unit will enable the entry and delivery units to be always operated in a correlated manner and maintained within a desirable operating range to thus cover a very wide range of entry strip conditions.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof.

I claim:

' 1. A method of producing flat metallic strip compris ing the steps of:

causing the strip to pass through a controlled elonga- 1 tion zone created by two spaced-apart strip tensioning means where the strip is subject to a substantial total tension but below its yield point, causing the strip while subject to said tension to pass around a series of strip flexing rolls where the strip is subject to reverse flexing whereby the tension and flexing imparts a controllable amount of permanent elongation to the strip, varying the unit tension transversely of said strip to vary the transverse unit tension of the portion of the strip being subject to the flexing operation, determining the transverse flatness profile of the strip when under said tension and between said tensioning means and changing at least one of said total tension, flexing or unit tension operations to reduce the non-flatness in the strip.

2. A method of producing flat strip according to claim 1,

wherein said strip flexing step includes subjecting the strip to a simultaneous rolling and flexing operation,

and changing atleast one of said total tension, rolling and flexing or unit tension operations to reduce the non-flatness in the strip issuing from said rolling and flexing operation.

3. A method of producing flat metallic strip according to claim I,

wherein said flexing operation includes the step of passing the strip between a set of three rolls, one of which is arranged in a nested relationship with the others and being of a much smaller diameter than the others.

4. A method of producing flat metallic strip according to claim 1, wherein said flexing operating includes the step of passing the strip through two succeeding and separate flexing operations wherein theopposite surfaces of the strip are subjected to an equal number of tension-compression steps caused by flexing.

5. A method of producing flat metallic strip according to claim 1 wherein said step of varying the unit tension of the strip is accomplished by varying the length of the path of travel of different portions of the strip width by manipulation of a deflecting roll arranged to engage one of the surfaces of the strip when subject to said total tension condition.

6. A method of producing flat metallic strip according to claim 5, wherein said variation of length of path of travel is accomplished by applying a bending mo -.ment to the ends of said deflecting roll.

7. A method of producing flat metallic strip according to claim 5, wherein said variation of length of path of travel is accomplished by applying a rotation to said deflecting roll about its minor axis.

8. A method of producing flat metallic strip according to claim 1, wherein said determining of the flatness profile of the strip is accomplished by causing the strip to engage a shape detecting roll arranged on either side of said flexing operation.

9. A method for producing flat metallic strip according to claim 8, wherein said strip is caused to engage said shape detecting rolls on the entry and delivery sides of said flexing operation.

it). A method of producing flat metallic strip according to claim ll, wherein said step of subjecting the strip to a substantial total tension includes with respect to said flexing step causing the strip to pass between entry and delivery tension bridle units.

ill. A method of producing flat metallic strip according to claim 1, wherein said step of subjecting the strip to a substantial total tension includes with respect to said flexing step, causing the strip to pass between entry and delivery tension bridle units,

and wherein said determining of the flatness profile of the strip is accomplished by causing said strip to engage a shape detecting roll arranged on either side of said flexing operation,

and wherein said step of varying the unit tension of the strip is accomplished by variation of length of path of travel by manipulation of a strip deflecting roll arranged to engage one of the surfaces of the strip when subject to said total tension condition,

and further wherein said flexing operation includes the steps of passing the strip through two succeeding and separate flexing operations wherein the opposite surfaces of the strip are subjected to an equal number of tension-compression steps caused by flexing.

12. A method of producing flat metallic strip according to claim ll, wherein said strip flexing operations include subjecting this strip to a simultaneous rolling and flexing operation and changing atleast one of said total tension, rolling and flexing, or unit tension operations to reduce for non-flatness in the strip issuing from said rolling and flexing operation.

13. An apparatus and control for producing flat metallic strip comprising:

means for passing the strip to a controlled elongation zone,

said elongation zone including two spaced-apart strip tension means for subjecting the strip to a substantial total tension but below its yield point,

said zone alsoincluding a series of strip flexing roll means constructed and arranged to subject the tensioned strip to reverse flexing whereby the tension and flexing imparts a controllable amount of permanent elongation to the strip,

a deflector roll arranged to be engaged by said tensioned strip,

means for manipulating said deflector roll to vary the unit tension transversely of the strip to thereby vary the transverse unit tension of the portion of strip n being subject to the flexing operation, and means arranged between said tension means for determining the transverse flatness profile of the strip while under said tension and for effecting a change in at least one of said total tension, flexing or unit tension operations to reduce the nonflatncss in the strip. 14. An apparatus and control according to claim l3, wherein said flexing roll means includes means for bringing said roll means in a rolling and flexing relationship with said strip.

15. Apparatus and control according to claim 113, wherein said flexing roll means includes a set of three rolls one of which is arranged in a nested relationship with the others and being of a much smaller diameter than the others.

16. An apparatus and control according to claim 13, wherein said flexing roll means includes two succeeding and separate sets of rolls constructed and arranged to subject the opposite surfaces of the strip to an equal number of tension-compression steps caused by flexing.

17. An apparatus and control according to claim 13, wherein said means for manipulating said deflector roll comprising a means for bending said roll in order to change its effective crown.

18. An apparatus and control according to claim l3,

wherein said means for manipulating said deflector roll comprises a means for cocking said roll by applying a rotational force about its minor axis.

19. An apparatus and control according to claim 13, wherein said means for determining the flatness profile of the strip includes a shape detecting roll arranged on either side of said strip flexing roll means.

20. An apparatus and control according to claim 13, wherein said means for subjecting the strip to a total tension includes with respect to said flexing roll means, entry and delivery tension bridle units. I

21. An apparatus and control according to claim 13, wherein said means for subjecting the strip to a substantial total tension comprises with respect to said flexing roll means, entry and delivery tension unit bridles,

said means for determining the flatness profile of the strip includes a shape detecting roll arranged on either side of said flexing roll means,

wherein said deflector. roll is arranged to engage one of the surfaces of said strip when subject to said total tension condition,

wherein said flexing roll means includes two succeeding and separate sets of flexing rolls wherein the opposite surfaces of the strip are subject to an equal number of tension-compression steps caused by flexing,

wherein said flatness profile determining means includes a shape detecting roll for producing a signal of the non-flatness condition of the strip, and

a control unit for receiving said signal from said detecting roll and producing a command signal to selectively and simultaneously vary one or more of the operations of said tot-a1 tension, flexing and unit

Claims

1. A method of producing flat metallic strip comprising the steps of: causing the strip to pass through a controlled elongation zone created by two spaced-apart strip tensioning means where the strip is subject to a substantial total tension but below its yield point, causing the strip while subject to said tension to pass around a series of strip flexing rolls where the strip is subject to reverse flexing whereby the tension and flexing imparts a controllable amount of permanent elongation to the strip, varying the unit tension transversely of said strip to vary the transverse unit tension of the portion of the strip being subject to the flexing operation, determining the transverse flatness profile of the strip when under said tension and between said tensioning means and changing at least one of said total tension, flexing or unit tension operations to reduce the non-flatness in the strip.

2. A method of producing flat strip according to claim 1, wherein said strip flexing step includes subjecting the strip to a simultaneous rolling and flexing operation, and changing atleast one of said total tension, rolling and flexing or unit tension operations to reduce the non-flatness in the strip issuing from said rolling and flexing operation.

3. A method of producing flat metallic strip according to claim 1, wherein said flexing operation includes the step of passing the strip between a set of three rolls, one of which is arranged in a nested relationship with the others and being of a much smaller diameter than the others.

4. A method of producing flat metallic strip according to claim 1, wherein said flexing operating includes the step of passing the strip through two succeeding and separate flexing operations wherein the opposite surfaces of the strip are subjected to an equal number of tension-compression steps caused by flexing.

6. A method of producing flat metallic strip according to claim 5, wherein said variation of length of path of travel is accomplished by applying a bending moment to the ends of said deflecting roll.

10. A method of producing flat metallic strip according to claim 1, wherein said step of subjecting the strip to a substantial total tension includes with respect to said flexing step causing the strip to pass between entry and delivery tension bridle units.

11. A method of producing flat metallic strip according to claim 1, wherein said step of subjecting the strip to a substantial total tension includes with respect to said flexing step, causing the strip to pass between entry and delivery tension bridle units, and wherein said determining of the flatness profile of the strip is accomplished by causing said strip to engage a shape detecting roll arranged on either side of said flexing operation, and wherein said step of varying the unit tension of the strip is accomplished by variation of length of path of travel by manipulation of a strip deflecting roll arranged to engage one of the surfaces of the strip when subject to said total tension condition, and further wherein said flexing operation includes the steps of passing the strip through two succeeding and separate flexing operations wherein the opposite surfaces of the strip are subjected to an equal number of tension-compression steps caused by flexing.

12. A method of producing flat metallic strip according to claim 11, wherein said strip flexing operations include subjecting this strip to a simultaneous rolling and flexing operation and changing atleast one of said total tension, rolling and flexing, or unit tension operations to reduce for non-flatness in the strip issuing from said rolling and flexing operation.

13. An apparatus and control for producing flat metallic strip comprising: means for passing the strip to a controlled elongation zone, said elongation zone including two spaced-apart strip tension means for subjecting the strip to a substantial total tension but below its yield point, said zone also including a series of strip flexing roll means constructed and arranged to subject the tensioned strip to reverse flexing whereby the tension and flexing imparts a controllable amount of permanent elongation to the strip, a deflector roll arranged to be engaged by said tensioned strip, means for manipulating said deflector roll to vary the unit tension transversely of the strip to thereby vary the transverse unit tension of the portion of strip being subject to the flexing operation, and means arranged between said tension means for determining the transverse flatness profile of the strip while under said tension and for effecting a change in at least one of said total tension, flexing or unit tension operations to reduce the non-flatness in the strip.

14. An apparatus and control according to claim 13, wherein said flexing roll means includes means for bringing said roll means in a rolling and flexing relationship with said strip.

15. Apparatus and control according to claim 13, wherein said flexing roll means includes a set of three rolls one of which is arranged in a nested relationship with the others and being of a much smaller diameter than the others.

18. An apparatus and control according to claim 13, wherein said means for manipulating said deflector roll comprises a means for cocking said roll by applying a rotational force about its minor axis.

20. An apparatus and control according to claim 13, wherein said means for subjecting the strip to a total tension includes with respect to said flexing roll means, entry and delivery tension bridle units.

21. An apparatus and control according to claim 13, wherein said means for subjecting the strip to a substantial total tension comprises with respect to said flexing roll means, entry and delivery tension unit bridles, said means for determining the flatness profile of the strip includes a shape detecting roll arranged on either side of said flexing roll means, wherein said deflector roll is arranged to engage one of the surfaces of said strip when subject to said total tension condition, wherein said flexing roll means includes two succeeding and separate sets of flexing rolls wherein the opposite surfaces of the strip are subject to an equal number of tension-compression steps caused by flexing, wherein said flatness profile determining means includes a shape detecting roll for producing a signal of the non-flatness condition of the strip, and a control unit for receiving said signal from said detecting roll and producing a command signal to selectively and simultaneously vary one or more of the operations of said total tension, flexing and unit tension means.