US3783667A

US3783667A - Apparatus for straightening metal by stretching

Info

Publication number: US3783667A
Application number: US00240135A
Authority: US
Inventors: C Munchbach
Original assignee: Individual
Current assignee: UNGERER I DT
Priority date: 1971-04-14
Filing date: 1972-03-31
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: DE2118051A1; DE2118051C3; GB1358936A; DE2118051B2; SE370505B; FR2133558B1; BE781993A; IT950137B; FR2133558A1; CA969001A; AT311765B

Abstract

In an apparatus for straightening a continuously running metal strip with a stretching operation, there provided a hold-back roll assembly and a drawing roll assembly; every roll in both roll assemblies has the same diameter and is, with the exception of the fastest roll in one assembly and the slowest roll in the other assembly, associated with a separate differential gearing, the output rpm of which is individually variable by a regulating device in accordance with the required rpm increase or rpm decrease of the associated roll with respect to the adjacent roll.

Description

United States Patent [1 1 Miinchbach Jan. 3, 1974 [54] APPARATUS FOR STRAIGHTENING 3,641,797 2 1972 Bell et al 72 205 x METAL BY STRETCHING 3,580,033 5/1971 Gay 72/205 3,427,848 2/1969 Gay 72/205 Inventor: Curt Munchbach, 3,377,830 4/1968 Campbell... 72/205 Pforzheim-Sonnenberg, Germany 3,362,202 1/1968 Gay 72/160 [73] Asslgnee' a 'i Primary Examiner-Milton S. Mehr P orzheim-Brotzingen, Germany Att0rney Edwin E. gg [22] Filed: Mar. 31, 1972 211 App]; No.: 240,135 [57] ABSTRAQCT In an apparatus for straightening a contznuously run- 1 ning metal strip with a stretching operation, there prol Foreign Applicatiofl Priority Data vided a hold-back roll assembly and a drawing roll as- Apr. 14, 1971 Germany ..P 21 18 051.8 sembly; every roll in both roll assemblies has the same diameter and is, with the exception of the fastest roll [52] U.S. Cl. 72/160, 72/205 in one assembly and the slowest roll in the other as- [5] B2ld 1/02, B2lb 39/08 sembly, associated with a separate differential gearing, [58] Field of Search 72/205, 160, 249 the output rpm of which is individually variable by a regulating device in accordance with the required rpm [56] References Cited increase or rpm decrease of the associated roll with UNITED STATES PATENTS respect to the adjacent roll. 3,626,737 12/1971 Defontenay 72/205 4 Claims, 5 Drawing Figures PMENIED JAN 8574 SHEET 2 OF 5 Fig. 2

II I SHEET 3 OF 5 PATENTED 8 5974 SHEET l 0F 5 Fg. z

II II APPARATUS FOR STRAIGHTENING METAL BY STRETCHING BACKGROUND OF THE INVENTION This invention relates to an apparatus for straightening a continuously advanced metal article, such as a metal strip, by a stretching operation. The apparatus is of the type that has a hold-back assembly formed of rolls in an S-arrangement, a device for setting the degree of stretch, and a drawing assembly formed of rolls in an S-arrangement. All the rolls have the same diameter and are rotatable by a common drive motor. The required step-down or step-up in the peripheral velocities of the different rolls is effected by differential gearings.

In known straightening apparatus of the aforenoted type a differential gearing is provided for every two rolls. The drive means is coupled to the differential housing. In this manner, in case of different rpms of the rolls, a compensation is effected by means of the compensating bevel gear of the differential gearing. A buildup of the tension from one roll to the other may occur only if the differential gearing is connected directly with one roll and through an intermediate ratio changing device with the other roll. The ratio changing device increases the direct transmission ratio of 1:1 by the value e to be discussed later. In case this value which expresses the possible tension increment factor from one roll to the other as a function of the looping angle and friction is exceeded, slippage will occur not only at that roll where such excess prevails, but also at the adjacent roll which is connected by means of the differential gearing. It is difficult to adapt such stretch-type straightening apparatuses to the operational requirements, since no provisions are made to adjust the individual drives. Furthermore, stretch-type straightening apparatuses of the aforenoted kind are very poorly adapted, if at all, for treating very thin metal strips because of the effect of frictional losses in the drive gear assembly.

OBJECT, SUMMARY AND ADVANTAGES OF THE INVENTION It is an object ofthe invention to provide an improved stretch-type straightening apparatus wherein the driving means for the S-rolls may be adapted rapidly and in a simple manner to the operational requirements while it remains unaffected by the efficiency of the drive gear assembly.

Briefly stated, according to the invention,in both the hold-back roll assembly and the drawing roll assembly, with each roll, with the exception of the roll driven with the highest or lowest speed in each roll assembly, there is associated a differential gearing, whose output rpm at the compensating gear carrier is variable by means of a regulating device in accordance with the required rpm increase or decrease with respect to the adjacent roll. 1

By making possible an rpm regulation of each roll, its rpm may be adapted to the modulus of elasticity of the material to be treated. Furthermore, in the determination of the roll rpm it is possible to take into account the adhesion effect of the strip surface, the frictional value of the individual rolls, as well as the change in the frictional values. The latter may occur due to the soiling of the rolls, the presence of oil or grease smudges, roll wear and regrinding.

It is a further advantage of the invention that the frictional losses in the drive gear assembly. dependent upon operational conditions (such as starting or braking), load conditions, the advancing speed of the material or the room temperature, do not eflect the accu racy of the set magnitudes transmitted from the drive gear assembly to the rolls. The aforenoted losses burden solely the motor which operates the drive gear assembly and have no effect on the value of strip adhesion of the individual rolls. By means of automatic (or manual) readjustment of the regulating device, the lowering of the frictional adhesion values caused at high strip speeds by air inclusion and centrifugal forces may be compensated.

The invention will be better understood as well as further objects and advantages become more apparent from the ensuing detailed specification of several exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view of an S-type roll assembly formed of three rolls;

FIG. 2 is a block diagram illustrating schematically the stretch-type straightening apparatus according to the invention and FIGS. 3, 4 and 5 are block diagrams of modified arrangements of the drive gear assemblies according to the invention.

DESCRIPTION OF THE EMBODIMENTS Turning now to FIG.1, a metal strip is trained in an S-configuration about parallel supported rolls 1, 2 and 3. Rolls 1 and 3 are at the same height whereas roll 2 is displaced therebelow.

The metal strip running onto the roll .1 from a reel (not shown) under an initial pull 8, engages the roll 1 through a looping angle a In accordance with the formula wherein e is the base of the natural logarithm,

p. is the value of friction between roll and strip face,

a is the looping angle and S and S are the strip tensions upstream and downstream of the roll 1, respectively,

S increases with respect to S as a function of the frictional value p. and the looping angle 01,. The strip runs onto the roll 2 under a tension S which equals S but which, because of the looping angle a, and the frictional value at the roll 2, increases to S as the strip runs off the roll 2. The tension of the strip increases in this manner from roll to roll until a strip tension 8,, is reached.

According to the formula wherein S is the strip tension between two rolls,

1 is the length of the free strip portion between two rolls,

A is the length increase of the strip between two rolls,

F is the sectional area of the strip and E is the modulus of elasticity of the strip material, the

, strip exposed to the pulling force S S undergoes along the length 1 between the run-off point of the roll 1 and the run-up point of roll 2 an elastic elongation A, which is a function of the modulus of elasticity E of the material and the pulling force S This elongation x, must be taken up slip-free by the roll 2 which is achieved by increasing the peripheral velocity thereof.

Since the stip tensions S 5,, etc. have to increase up to the value of the stretching pull S the elongations for strips of different cross section F are different between the individual rolls at structurally given fixed looping angles. Therefore, in a stretch-type straightening apparatus the circumferential velocities of the invididual rolls in the hold-back assembly have to increase from roll to roll, while they have to decrease in the drawing assembly. This change in the circumferential velocity of the rolls may be achieved either by providing rolls of different diameters in which case the rpms are identical or, if the roll diameters are the same, then the rpm s have to be different.

In FIG. 2 there is schematically shown a drive gear assembly with the aid of which the different peripheral velocities of the rolls may be set, while each roll diameter has the same value. The drive gear assembly according to this exemplary embodiment serves a hold-back assembly and a drawing assembly formed of four rolls each.

In the embodiment illustrated in FIG. 2, the holdback assembly has four

rolls

16, 17, 18 and 19 and the drawing assembly has four

rolls

20, 21, 22 and 23. All these rolls are engaged by a running strip (not shown) in a manner similar to that illustrated in the three-roll S-assembly described with reference to FIG.1. As seen, in the hold-back

roll assembly rolls

16, 19 are the outermost rolls, while rolls 17, 18 are intermediate rolls, whereas in the drawing

roll assembly rolls

20, 23 are the outermost rolls, while rolls 21, 22 are intermediate rolls. It is further apparent that the material, when the entire straightening apparatus is considered, runs onto roll 16 and runs off roll 23.

For the driving of all the rolls there is provided a drive motor 24 which rotates a main drive shaft 25 of the hold-back assembly. The shaft 25 drives a stretch setting device 26 having an output shaft 27 which constitutes the main drive shaft for the drawing assembly. Since the drive gear assembly associated with the drawing assembly is identical in structure and operation to that of the hold-back assembly, in the description that follows only the drive gear assembly of the latter will be set forth in detail.

The main drive shaft 25 rotates the first roll 16 through a miter gear 28 and a drive shaft 29. As it has been explained in connection with FIGJ, the first roll 16 of the hold-back assembly turns with the smallest rpm with respect to the other rolls 17-19. Each

roll

17, 18, 19 rotates somewhat faster than the preceding roll in the hold-back assembly; for this purpose, each

roll

17, 18, 19 is connected with the main drive shaft 25 through a separate gear assembly 40 which has two input shafts 31 and 35 driven through

miter gears

30 and 34 by the main drive shaft 25. It is noted that since each gear assembly 40 in the hold-back assembly is of identical structure and function, only that associated with roll 17 is described in detail. Thus, the output shaft 33 extending from the gear assembly 40 is connected with the roll 17.

The gear assembly 40 includes a differential gearing 32 which is driven by the input shaft 31 and which has an output shaft that constitutes the output shaft 33 of the gear assembly 40. The input shaft 35 is associated with a steplessly adjustable non-slip gear ratio regulating device 36 (for example, a P.I.V. drive), which, in turn, is connected with the compensating gear carrier of the differential gearing 32 through an intermediate shaft 37, a step-down gear 38 and a further intermediate shaft 39. The rotational direction of the intermediate shaft 39 is so selected that the rpm of the output shaft 33 is increased with respect to the input shaft 31 to correspond to the required rpm increase of the roll 17 with respect to the roll 16.

By virtue of the gear assembly 40 the roll 17 has a somewhat higher peripheral velocity than that of the roll 16 for taking up the afore-explained strip elongation A The extent of the rpm increase which depends on factors discussed earlier, is automatically or manually regulated in a stepless manner with the regulating device 36. With a correspondingly large control range of the regulating devices 36 any desired roll rpm may be set in the other gear assemblies 40.

By means of the stretch setting device 26, the rpm of the main drive shaft 25 transmitted to the hold-back assembly is transformed, as a function of the extent of pull, into a higher rpm for the main drive shaft 27 and is thus transmitted to each gear assembly 40 of the drawing assembly.

Since by selecting the direction of rotation of the gear train 36, 38 operating in shunt, the rpm of the output shaft 33 is increased or decreased with respect to the rpm of the input shaft 31, various arrangements of drive gear assemblies are possible which are illustrated in FIGS. 3, 4 and 5. Each gear assembly, however, has to be designed in such a manner that in each case the first roll 16 in the hold-back assembly and the last roll 23 in the drawing assembly have the smallest rpm within their respective roll assembly.

In FIG. 3 in each roll assembly (that is, the hold-back roll assembly 16-19 and the drawing roll assembly 20-23), the rolls having the highest rpm, that is rolls 19 and 20, are directly driven by the

main drive shafts

25 and 27,whereas the adjoining rolls of decreasing rpms are driven by the gear assemblies 40.

In the arrangement according to FIG. 4, the holdback assembly corresponds to the arrangement according to FIG. 2 and the drawing assembly corresponds to the arrangement according to FIG. 3. Thus, the individual gear assemblies 40 of the hold-back assembly transmit an increasing rpm in the direction of the roll 19, whereas the individual gear assemblies 40 of the drawing assembly operate with decreasing rpms.

In the driving arrangement shown in FIG. 5 the holdback assembly corresponds to the arrangement according to FIG. 3 and the drawing assembly corresponds to the arrangement according to FIG. 2. Thus, in the holdback assembly the roll 19 is driven directly, whereas the preceding rolls are driven with gradually decreasing rpms. In the drawing assembly the roll with the lowest rpm (that is, roll 23) is directly driven by the main shaft whereas the preceding rolls are driven by means of the individual gear assemblies 40 with increasing rpms starting with roll 22 down to roll 20.

The drive motor 24, as it can be observed from FIGS. 2-5, is associated in each case with the miter gear of the hold-back assembly from which the driving of the corresponding roll is effected in a direct manner.

In view of the fact that the regulating devices 36, as it has been noted earlier, operate in a shunted manner, and further, since the output rpm of each regulating device is significantly decreased by an associated stepdown gear, the effect on the roll of any possible rpm error in its regulating device is reduced to a negligible value. This is so, because the roll rpm increments generated by driving the compensating gear carrier of the differential gearing, are in the range of a few thousandths of the rpm of the roll.

I claim:

1. In a stretch-type straightening apparatus of the known type that has (a) a hold-back roll assembly formed of a plurality of rolls in an S-arrangement, two of the rolls in the hold-back roll assembly being outermost rolls and the remainder being intermediate rolls, (b) means for driving each roll in said hold-back roll assembly with an rpm that is greater than the rpm of any of the upstream rolls in the hold-back roll assembly, (c) a drawing roll assembly formed of a plurality of rolls in an S-arrangement, two of the rolls in the drawing roll assembly being outermost rolls and the remainder being intermediate rolls, all the rolls in both for driving each roll in said drawing roll assembly with an rpm that is smaller than the rpm of any of the upstream rolls in said drawing roll assembly, (e) a stretchsetting device determining the extent of material tension between the two roll assemblies and (f) a common drive motor for rotating all the rolls, the improvement comprising A. a separate differential gearing connected to every intermediate roll and to one of the outermost rolls in both roll assemblies, each differential gearing having a compensating gear carrier and B. a separate regulating device connected at least indirectly to the compensating gear carrier of each differential gearing for providing an rpm of the associated roll that is different from the rpm of any other roll in the same roll assembly.

2. An improvement as defined in claim 1, including a main drive shaft rotated by said common drive motor and connected to each said regulating device and to each said differential gearing.

3. An improvement as defined in claim 2, including means for steplessly adjusting each regulating device.

4. An improvement as defined in claim 1, including a step-down gearing connected between each regulating device and its associated differential gearing.

Claims

1. In a stretch-type straightening apparatus of the known type that has (a) a hold-back roll assembly formed of a plurality of rolls in an S-arrangement, two of the rolls in the hold-back roll assembly being outermost rolls and the remainder being intermediate rolls, (b) means for driving each roll in said holdback roll assembly with an rpm that is greater than the rpm of any of the upstream rolls in the hold-back roll assembly, (c) a drawing roll assembly formed of a plurality of rolls in an Sarrangement, two of the rolls in the drawing roll assembly being outermost rolls and the remainder being intermediate rolls, all the rolls in both roll assemblies having the same diameter, (d) means for driving each roll in said drawing roll assembly with an rpm that is smaller than the rpm of any of the upstream rolls in said drawing roll assembly, (e) a stretch-setting dEvice determining the extent of material tension between the two roll assemblies and (f) a common drive motor for rotating all the rolls, the improvement comprising A. a separate differential gearing connected to every intermediate roll and to one of the outermost rolls in both roll assemblies, each differential gearing having a compensating gear carrier and B. a separate regulating device connected at least indirectly to the compensating gear carrier of each differential gearing for providing an rpm of the associated roll that is different from the rpm of any other roll in the same roll assembly.