US3416341A

US3416341A - Rolling mill control system

Info

Publication number: US3416341A
Application number: US600928A
Authority: US
Inventors: Dey Chester; Smith Arthur Dean
Original assignee: Kaiser Aluminum and Chemical Corp
Current assignee: Kaiser Aluminum and Chemical Corp
Priority date: 1966-12-12
Filing date: 1966-12-12
Publication date: 1968-12-17
Anticipated expiration: 1985-12-17
Also published as: FR1587488A; GB1237287A; DE1802786A1

Description

Dec. 17, 1968 C. DEY ET AL 3,416,341

ROLLING MILL CONTROL SYSTEM Filed Dec. 12, 1966 2 Sheets-Shet 1 IINVENLTORS QL CHESTER DEY 72 50 56 52 A. DEAN SMITH Dec. 17, 1968 c. DEY ETAL 3,416,341

ROLLING MILL CONTROL SYSTEM Filed Dec. 12, 1966 2 Sheets-Sheet 2 INVENTORS CHESTER DEY BY A. DEAN SMITH United States Patent 3,416,341 ROLLING MILL CONTROL SYSTEM Chester Dey, Piedmont, and Arthur Dean Smith, San

Lorenzo, Calif, assignors to Kaiser Aluminum &

Chemical Corporation, Oakland, Calif., a corporation of Delaware Filed Dec. 12, 1966, Ser. No. 600,928 17 Claims. (Cl. 72-20) The invention relates to rolling mills and more particularly to an improved roll gap control system therefor wherein the functions of a rolling mill pushup control means and a rolling mill roll bending control means are both fully integrated with each other during operation of the rolling mill and wherein the pushup means are also operated in an improved fashion so that the material being rolled will maintain a substantially uniform gauge across its entire width irrespective of changes in various mill load conditions which occur during rolling.

In prior rolling mill practices, in order to maintain substantially uniform gauge across the entire width of the material being rolled, it has been customary to use work or backup roll bending devices and roll pushup devices. The bending devices apply bending loads to the work rolls to counter or compensate for deflection of certain portions of the rolls due, for example, to separating forces exerted upon the rolls by the workpiece, roll heat up, roll flattening, etc. Roll pushup devices, such as pushup cylinders, are used in addition to the normal roll screw down devices primarily to compensate for stretching of the mill housing or frame, which also normally occurs as a result of the separating forces exerted directly upon the work rolls and indirectly on the mill frame by the material, such as metal sheet, that is rolled. Despite all of these corrective measures, problems still exist because of the failures that have occurred to date in efliciently and reliably integrating the control system for the roll bending devices with the control system for the pushup devices whereby each control system will still perform its assigned function, as such, while at the same time taking into account and at the same time synchronizing its operations with those of its companion control system so that the desired optimum roll gap setting for the mill is constantly maintained throughout rolling.

Accordingly, it is a primary purpose of the instant invention to provide, among other things, an improved and highly reliable control arrangement for operating and integrating a mill roll bending device with a mill roll pushup device, whereby each device will efliciently perform its own assigned function, as such, while at the same time being fully synchronized with its companion device whereby one device will not only not adversely affect the operation of the other device, but instead will advantageously complement the workings of the other device in maintaining the desired optimum roll gap setting for a given rolling operation.

This and other purposes and advantages of the instant invention will become more apparent from a review of the following detailed description when taken in conjunction with the appended drawings, wherein:

FIG. 1 is a side elevational view of a typical rolling mill with certain parts removed and other parts broken away and incorporating the improved integrated control systems of the instant invention;

FIG. 2 is a sectional view generally taken along line 22 of FIG. 1 with parts of the mill being removed and with other parts being schematically shown for purposes of illustration and with the integrated mill control systems of the instant invention being schematically added to illustrate the novel details thereof; and

FIG, 3 is a diagrammatic view of a modified form of the integrated control systems of FIG. 2.

3,416,341 Patented Dec. 17, 1968 With further reference to the drawings and in particular FIGS. 1 and 2, a preferred form of apparatus that can be used in carrying out the teachings of the instant invention generally comprises a typical four-high rolling mill stand 10 used to roll ferrous or non-ferrous metals. Mill stand 10 includes a mill housing or framework 12, a pair of backup rolls 14 and a pair of work rolls 16. Although the forming surfaces of the work rolls 16 along their axial lengths are shown to have a uniform diameter, these surfaces can, if desired, be initially made to have an axial convex or concave shape in accordance with customary roll finishing practices.

Rolls

14 and 16 are rotatably and adjustably mounted within the framework 12 by the journal or reduced ends of

rolls

14 and 16 being appropriately mounted in their

respective chock blocks

26 and 28 and these

chock blocks

26 and 28 are then slidably mounted within vertically recessed track means in the window 13 of the housing 12 in the usual fashion as indicated by the dotted lines in FIG. 1. It is to be understood, of course, although not shown, that the customary jack rams such as those shown in United States Patent 2,903,926 to R, M. Reichl, issued Sept. 15, 1959, or other appropriate upper roll and upper chock block counterbalancing devices are used on the mill illustrated in order for the upper rolls and chock blocks to follow the upward movements of the upper screw downs and remain in contact therewith during adjustments thereto.

As indicated in FIGS. 1 and 2, in order to assist in establishing the proper setting of the roll gap 38 between the work rolls 16 in accordance with the desired gauge for the workpiece W to be rolled, a pair of conventional feed screws or screw down devices 30 are disposed within threaded openings in the upper portion of the framework 12. The ends of the screws 30 are kept in abutting contact at 32 with the chock block elements 26 for the upper roll 14 and screws 30 are adjustable by conventional actuating means (not shown).

In the rolling mill illustrated, the chock blocks 26 associated with the ends of the lower backup roll 14 are interconnected to the lower portion of the framework 10 by conventional fluid actuators or pushup devices 33 which include pistons mounted in openings 34 and rod elements 36 directly connected to the chocks 26. These fluid actuators 33 act primarily to compensate for the spreading apart of the rolls, changes in the preselected roll gap setting 38 between rolls 16 and mill housing stretch resulting from insertion of a workpiece W between the rolls and the consequent rolling loads applied to the rolls by a workpiece W during rolling. In their operation, devices 33 act in conjunction with the mill screws 30 to bring the rOlls back to the desired roll gap setting.

Although other tying arrangements can be used, an advantageous embodiment of the invention contemplates that the ends of the backup rolls 14 in the apparatus illustrated be interconnected to each other by extensible fluid actuators 42. The purpose of these actuators is to apply appropriate bending loads to the work rolls when needed at the same time that appropriate pushup loads are applied to the rolls by the actuators 33.

The overall control circuit generally indicated at 20 in FIG. 2 for the

fluid actuators

42 and 33 includes improved means for fully integrating and correlating all applied bending loads with the rolling loads applied by the workpiece W and counter-loads applied by the pushup actuators 33 at any given time in order to maintain the desired roll setting gap substantially uniform across the full length of the work rolls whereby the workpiece W will be rolled with the desired substantially uniform gauge across its full width.

The control circuit 20 in the embodiment of FIG. 2 includes an improved circuit component sensing means comprised of a gauge rod 74 and a sensing device or load cell 76. Load cell 76 can be a conventional sensing element of the type sold by Asea Electric, Inc., of San Francisco, Calif, under Model No. TGPUB-ZOO and under the trade name Pressductor.

The load cell 76 is connected to a hydraulic circuit for selectively controlling the admittance of fluid under pressure to the fluid actuators or pushups 33 for expanding or collapsing the pushup devices in a manner to be described more fully hereinafter. The hydraulic circuit includes a pump 56 connected by a conduit 51 to a source of supply or reservoir 55.

Branch lines

50 and 52 lead from main line 51 to the various actuators 33. In the event of build-up of excess pressure fluid within the actuators 33 and

conduits

50 and 52, control valves 66, connected to each

conduit

50 and 52, can be preset whereby they automatically function to exit the excess fluid through the line 57 to the reservoir 55.

Also included in the overall control circuit 20 is a further hydraulic circuit for controlling the admittance of fluid under pressure to the fluid actuators 42 for applying the desired bending loads to the backup rolls 14 and in turn to the work rolls. Each fluid actuator 42 can include a fluid cylinder 44 within which a piston 45 is slidably disposed. The exposed end of the rod for piston 45 as well as one end of the cylinder 44 can be provided with apertured enlargements 46 within which the journal ends of the rolls 14 can be disposed as shown in FIG. 2. Thus, the cylinder 44 can be affixed to one backup roll and the piston 45 to the other backup roll. A pump 64 is used to supply fluid under pressure to opposite sides of the piston 45 disposed within the cylinder 44. This pump supplies fluid under pressure from a source of supply or reservoir 58 through a main conduit 63 to an appropriate control valve 80. Valve 80 operates to distribute fluid under pressure to either side of the pistons 45 disposed within the cylinders 44 by the interconnected

branch conduits

60 and 62, which lead to the free sides of the pistons 45 and by the other interconnected

branch conduits

65 and 67 which lead to the rod sides of the pistons 45 in accordance with specific roll bending requirements. Control valve 80 can also be preset depending upon the requirements for fluid under pressure to either side of the pistons 45 within the cylinders 44 of the actuators 42, to exit any excess fluid through the exhaust line 69 to the reservoir 58.

Control valves 66 for actuators 33 operate in response to appropriate electrical signals transmitted through the lead lines 68 and generated by their respective separate summing amplifiers 70. Suitably calibrated means such as an adjustable rheostat device 72 is connected to each of the amplifiers 70 for feeding the appropriate reference signal into the input side of an amplifier 70.

Each set of electrical elements or electrically

responsive elements

66, 70 and 72 is separately connected to one of the fluid actuators 33. If desired, the rheostat devices 72 of both sets of elements can be mechanically interlocked together, as schematically shown in dotted lines in FIGS. 2 and 3, whereby adjustment of one rheostat device 72 will automatically cause a corresponding adjustment of the other rheostat 72.

A brief discussion is believed to be in order at this point of how the rheostats 72 act in conjunction with load cells 76 and pushups 33 along with screws 30 in the operational set up and working of the mill. In setting up the mill stand for normal operation and with the mill stand being empty of a workpiece, the fluid actuators 33 are first actuated whereby they will raise the lower work roll 16 and backup roll 14 to the point where the bottom tips of the rods 74 for the load cells 76 are brought into contact with the chock blocks 26 for the lower backup roll 14. This may be referred to as the step of preloading the load cells 76. This preloading of the load cells is, in the case of any given mill installation, determined by the rolling requirements for the mill and the particular load cell used. Thus, in the present instance a load cell 76 may, for example, require a 20,000 lb. load to be applied thereto in order to place it in the desired preloaded condition. At this time, rods 74 are in the desired physical and pressure contact with lower chocks 26. This preloading of cells 76 is accomplished by the rheostats 72 which are calibrated in terms of pushup loads or load pounds, and once they have been set to the above 20,000 lb. load for the mill stand illustrated, they will for all practical purposes require no further attention. When fully set, rheostats transmit the proper reference signals to amplifiers 70 which operate valves 66 so that the actuators 33 are motivated to raise lower chocks 26 to the point where they are brought into proper pressure contact with rods 74 connected to load cells 76. After preloading of the load cells 76, the mill operator next adjusts screws 30 and the jack rams (not shown) to bring the upper backup and upper work rolls down until they are properly spaced the appropriate amounts from lower backup and lower work rolls to give the proper gap setting 38 for a given rolling condition, say .055".

When a workpiece is later inserted between the work rolls and the rolls are forced apart, it will be observed that the desired pressure contact will be lost between the load cell rods 74 and lower chock blocks 26 thereby causing the load cells 76 to become unloaded. As the cells become unloaded, they transmit appropriate feed back signals to amplifier 70 which then compares these signals with those from rheostats 72. The difference in signals causes amplifiers 70 to signal valves 66 to actuate the pushups 33 and raise

rolls

14 and 16 upwardly and lower chocks 26 back to the point Where they are again in the proper pressure contact with rods 74 for the load cells 76, thereby reestablishing the proper loading of the load cell 76 to the point (cg. 20,000 lbs.) where cells 76 discontinue the feedback signals to amplifiers 70 and bring about a deactivation of actuators 33.

Put another way, the normal operation of the load cell 76, rheostats 72 and actuators 33 can be expressed in terms of a conventional rolling mill formula used when load cell devices 76 are incorporated in a mill stand. Normal pushup loads (P), i.e. the final loads to be applied by actuator devices 33 in compensating for the final rolling loads applied to the rolls including that of the workpiece that passes therethrough and spreads the rolls apart and for reestablishing the loading of the load cells 76, is equal to the load cell load (LC) plus the final rolling load. Thus, (P)=(LC)+(RL).

Thus, in the above formula, if a load cell 76 as manufactured and installed is set to operate at a load cell load (LC) of 20,000 lbs. and the rheostats 72 are set at the 20,000 lbs. and the rolling load (RL) including that applied by the workpiece to the rolls as it is introduced into the mill which results in roll separation equals 180,000 lbs., the final pushup loads that must be applied to restore the load cells 76 to their balanced or loaded condition and the roll gap 38 to say the above mentioned .055" would be 200,000 lbs.

In order to efliciently perform the aforesaid operations, the load cell sensing elements 76, there being one of these elements on each side of the mill stand 10, are connected to the vertically disposed and laterally spaced gauge rods 74 positioned within each window 13 of the framework 12 adjacent the journal ends of the

rolls

14 and 16. The upper ends of the gauge rods 74 are disposed preferably immediately adjacent the lower surface portion to the frame 12, while their lower ends, which are preferably rounded off, rest upon and have the desired floating pressure contact with the upper surfaces of the chock blocks 26 associated with the lower backup roll 14. To facilitate vertically free but laterally restrained movement of each gauge rod 74 and loading and unloading of the cells 76, the rods 74 are passed through appropriate vertically disposed passageways in upper chock blocks 26 and 28 and lower chock block 28. These passageways are indicated by the dotted lines 77 in FIGS. 1 and 2. Due to this mounting arrangement, movements of the upper chocks 26 and 2-8 during initial screw down operations will have no effect on cells 76.

Although it is to be understood that a pair of active sensing devices 76 can be mounted on each side of the mill in the upper portion of the frame 12 for engagement with the upper ends of the rods 74 in each window 13, only one active sensing device 76 need be used for each side of the mill stand in actual practice.

In some instances, it may also be desirable to use a dummy or follower rod 74 in combination with a fully operative sensing rod 74 in each window and with one end of the dummy rod resting on the lower chock 26 and with its upper end contacting the undersurface of the frame 12. In such instances, the dummy or follower rods can act as vertical guides for the lower chock block 26 upon which the operative sensing rod 74 rests so that the lower block will be restrained and cannot take on simultaneous twisting movements about the axis of the rolls.

Each sensing element 76 is electrically connected to one of the amplifiers 70 by a line 77 (see FIG. 2) and operates in response to appropriate pressures exerted by contact with a lower chock 26 through its associated gauge rod 74 to transmit appropriate feed back signals to its associated amplifier 70 when deviations occur in the 20,000 lb. pushup loads as determined by the original reference signal being transmitted through rheostats 72, all as noted above. The signals transmitted by a sensing element 76 are opposite in polarity to the initial 20,000 lbs. reference signals transmitted from the rheostats 72 to the amplifiers 70. Whenever the feed back signals from cells 76 to the summing amplifiers 70 are in effect substantially cancelled out by the signals being transmitted to the amplifiers by the preset rheostats 72, either during the initial start up with no workpiece W between the rolls or during rolling when the gap 38 has exceeded the desired gauge setting, valves 66 will cease operating and stop the further flow of pressure fluid into the bottom sides of fluid actuators 33. This signal cancellation as noted above occurs at the time the pushup loads from the actuators 33 have loaded the cells 76 at the requisite (LC) load of 20,000 lbs. or at the time sensing rods 74 are in the appropriate pressure contact with the lower chocks 26.

By the contact pressure mounting of the sensing gauge rods 74 in the manner aforedescribed, the rods and in turn cells 76 are not adversely influenced in their operation by external loads imposed thereon, such as by the weight of rolls or the chock blocks or by any torque of the feed screws whereby inaccurate or non-reliable feed back signals could be transmitted to the amplifiers 70 by the sensing elements 76. Thus, the sensing devices 76 perform their roll separation and rolling load detection functions through the medium of amplifiers 70, etc. in an extremely sensitive and highly reliable fashion and efliciently operate the compensating pushups 33.

The electrical components of circuit 20 used to operate and control the roll bending actuators will now be described. Main control valve 80 is electrically connected to a summing amplifier 76 by line 78 whereby, depending upon the type of signal received from the amplifier 76', the control valve operates to direct fluid under pressure from pump 64 through the

proper branch conduits

65 and 67 or 60 and 62 to the various sides of the pistons to effect bending of the backup rolls and in turn the work rolls in the fashion desired.

Excess fluid from the supply conduit 63 or fluid returned from the various sides of cylinders 44 by the conduits and 62 or 65 and 67 as the case may be is at the same time directed by the valve 80 through the conduit 69 to the reservoir 58. An adjustable rheostat 74 calibrated in the appropriate roll bending load pounds is also connected to the input side of the summing amplifier 76' and is manipulated at the proper time by the mill stand operator to transmit the appropriate roll bending reference signal thereto. The amplifier 76 then continues the transmission of this signal through line 78 to the valve 80 and valve 80 operates to cause admittance of selected amounts of fluid under pressure to actuators 42 so as to apply the desired bending loads to the backup and work rolls 16.

The incorporation of bending rolls in the mill stand aggravates the problem of maintaining the desired roll gap 38 at say the above .055" across the length of the rolls since the application of the roll bending loads will increase the rolling loads (RL) and apply additional forces on the pushup actuators 33 which must be compensated for. This means then if the overall mill compensation is to be obtained, operation of the roll bending and pushup devices must also be fully correlated and synchronized with each other if the pushups are to continue to perform their proper function.

This correlation has been effected in the instant invention by way of a unique interlock or integration of the various pushup and bending roll components in the overall circuit 20. This component interlock involves use of an auxiliary summing amplifier 86 and suitable load feed back sensing

devices

82, 88, and 92, all of which can be of the type which translate or convert a given fluid pressure at any given time into an appropriate electrical signal. These

sensing devices

82, 88, 90 and 92 can be of the type sold by Computer Instrument Corporation of New York under Model No. 3000. The sensing devices 88 and 90 are disposed within the branch conduits of the pushup actuator fluid circuit immediately adjacent the pushup devices 33 as shown in FIG. 1. The other sensing devices are both disposed within the branch conduit 60 of the roll bending fluid circuit for constantly sensing the fluid pressure within the roll bending actuators 42. Sensing devices 88 and 90 are both electrically connected by their separate output lines 89 to the input side of the auxiliary summing amplifier 86. Sensing device 92 is likewise connected by its output line 91 to the input side of amplifier 86 and output line 84 connects the remaining sensing device 82 to the input side of the summing amplifier 76'. A rheostat 94 is also electrically connected across the output of amplifier 86 to the input side of amplifier 76'.

When no workpiece W is in the mill and with the initial pushup load setting preset at 20,000 lbs. by initial adjustment of the rheostats 72 in the manner aforedescribed, the output signal from amplifier 76' can be such as to normally produce no actuation of valve 80 and no application of bending loads to the rolls 1-6 and 14. When, however, a workpiece is passed through the mill and a roll bending operation is required for any reason, such as roll heat up, etc. to reestablish the desired roll contour for rolling, the operator moves rheostat 74 to the proper roll bending load application position.

In the case of where a constant roll bending load is to be applied, the operator merely adjusts rheostat 74,

leaving the other rheostat 94 in the circuit between am plifiers 86 and 76' in a zero or at rest position. By turning this roll bend pressure adjusting rheostat 74 to increase pressures in actuators 42, a positive signal is fed to the roll bending summing amplifier 76' and if no countersignal is fed back from the roll bending pressure sensor 82 the signal to valve 80 will continue to be positive until valve 80 has fully operated to build up the necessary pressures in actuators 42. As the pressure builds up, the pressure sensor 82 will feed back negative signals to summing amplifier 76' or signals opposite in polarity to the signals set by rheostat 74. When the signals from rheostat 74' are substantially equated with the signals from sensor 82, the signals from amplifier 76' to the valve 80 will cease and shut off valve 80 when the desired roll bending pressure is reached.

An increase in roll bending cylinder pressure, however, will also cause the additional application of pressure on the pushup cylinders thus, in effect, increasing the rolling load which will relieve the pressure on the load cells as contact is lost between rods 74 and the lower chock blocks 26. This loss of pressure on the load cells will result in the unloading of the load cells and cause the signals from the load cells 76 to amplifiers 70 to be appropriately negative. The signals then emanating from amplifiers 70 as determined by the difference between load cell signals and rheostats 72 will cause whatever increase in the pushup cylinder pressure is needed to reload cells 76 and compensate for the roll bending pressure and the mill housing stretch due to the new increase in rolling load.

This additional pushup loading will, however, usually cause undesirable roll deflection from the bending deflection desired which will now be reflected by feed back signals from

sensors

82 and 92 and, consequently, may require additional roll bending to compensate for the increase in pushup loading.

This is done automatically in the following fashion. It will be remembered that auxiliary summing amplifier 86 receives feed back signals both from pushup load sensors 88 and 90 and a roll bending load sensor 92. The feed back signal in line 91 from sensor 92 is opposite in polarity to the signals from the pushup sensors in lines 89 and this feed back signal reflects the loss in the desired bending roll pressures as set by rheostat 74'. All of these signals are new combined with one another at amplifier 86 and the algebraic sum of the two sets of signals, which are properly calibrated as regards each other in amplifier 86, is used as a further signal that can be fed to amplifier 76' and this further signal is superimposed upon the original signal transmitted through amplifier 76 and as initially received from rheostat 74. It will also be remembered that roll bending sensor 82 continues to operate at the same time and when the feed back signals from line 84 coming from bending roll sensor 82, which are opposite in polarity to the net input signals received by amplifier 76' from rheostat 74 and amplifier 86, substantially reaches the value of the aforesaid net input signals activation of valve 80 will cease and the desired balance between bending roll actuators and pushup actuators will be reached. In the aforesaid operation of amplifier 86, the algebraic sum of the signals from

sensors

88 and 90 and 92 can be regarded as amounting to the final or overall rolling load, (i.e. bending load plus the superimposed workpiece load) plus the contant preset load cell pressure, which final rolling load is to be equated by the final pushup loads.

Thus, any increase in the overall rolling load will be followed instantly by the required pushup pressures and pushup loads. If further compensating bending loads are required they too are made readily available. In order to keep the aforesaid process from cascading, since it must be remembered that load cells 76 are also functioning at the same time to maintain load cell pressure, until both the roll bend pressure and the pushup pressure are at the maximum, preferably not more than 50 percent of the differential pushup pressure signals from amplifier 86 are fed to the roll bending summing amplifier 76'. This is accomplished by means of the rheostat 94 interposed in the circuit between amplifiers 86 and 76'. Rheostat 94, of course, can be adjusted to increase or even further decrease the signals from amplifier 86 or to make other minute adjustments in the feed to amplifier 76'. These

amplifiers

70, 76' and 86 can be of the type sold by Burr-Brown Research Corporation of Tucson, Ariz., as Model Nos. 1506 or 1507. Instead of rheostat 94, a suitable function generating device can be employed, which can be made to vary the effect of amplifier 86 with relation to any desirable variable, such as rolling load, temperature of work rolls, etc.

In the modified form of the control circuit 57 of FIG.

3, in which parts corresponding to previously described parts are used and given the same reference numerals unless otherwise specified, it is contemplated that the gauge rods 74 and load cells 76 would be removed from the mill 10 of FIGS. 1 and 2. Thus, with the

rolls

14 and 16 being so disposed relative to each other within the mill 10 whereby for all practical purposes there is no gap between the rolls 16 and prior to entrance of a workpiece therebetween, the modified circuit of FIG. 3 is adjusted in such a fashion by adjustments of rheostats 72 so as to apply a predetermined pushup load on the backup and work rolls in accordance with expected rolling load conditions and established rolling practices. This preselected pushup load setting can then be used as a main reference point for operation of the modified overall control circuit 57 of FIG. 3.

Thus, in the instance of control circuit 57, the sensing devices 88' and 90', which are similar to sensing devices 88 and 90 previously described, are used to constantly sense or monitor the fluid pressure of the pushup components in the overall circuit 57. They are each advantageously connected in parallel by their separate lines 96 to the auxiliary summing amplifier 86 as before and in addition to different ones of the two summing amplifiers 70. The sensing device 92, which is similar to device 92, within the roll bending load component part of circuit 57 is not only connected by the line 98 to the amplifier 86 in the roll bending load part of the circuit as before, but it is also connected and interlocked in parallel to one of the summing amplifiers 70 in the pushup load portion of the circuit. The other sensing device 82, which is similar to previously described sensing device 82, and is located within the bending load component part of the circuit, is not only electrically connected by the line 100 to an amplifier 76' in the roll bending portion of the circuit as before, but it is also connected and interlocked by the same line 100 to the other summing amplifier 70 in the pushup load portion of the circuit. The electrical signals transmitted by the roll bend load feed back sensing devices 82' and 92' are normally of the same polarity as the initiating pushup signals received from the rheostat load setting devices 72 but opposite in polarity to the signals normally received from the feed back sensing devices 88 and 90' used in sensing the fluid pressures in the lines for the pushup actuators 33.

By virtu of the aforesaid interlocking of the several sensing devices 88', 90', 82 and 92', the signals from rheostats 72 are used as follows to set the pushup actuators to a given pressure position so that the desired roll gap will be established and maintained during a given rolling operation. When additional pushup pressures are needed to compensate for the rolling load applied to the rolls by a workpiece W, the feed back signals from sensors 88 and 90 transmitted to amplifiers 70 reflect this and amplifiers. 70 will operate to produce the neces sary actuation of valves 66 until the signals from sensors 88 and 90 are again substantially equated with the signals from rheostats 72. If the aforesaid rolling load is further increased by operation of the roll bending actuators 42 so that a new overall rolling load exists, sensors 82 and 92' in addition to feeding back signals to the main roll bending load amplifier 76' also feed back signals to the summing amplifiers 70 along with feed back signals from sensors 88 and 90 until the algebraic sum of the feed back signals of the sensors 88, 90" and sensors 82' and 92' substantially equate the original signals fed to amplifiers by the presetting of amplifiers 70 by rheostats 72' and thereby indirectly reestablish the desired roll gap setting as determined by the original presetting of rheostats 72.

Conversely, if the pushup pressures at any time become so great whereby the signals to amplifier 76' become unbalanced and applied roll bending loads and roll contour are adversely affected, the feed back signals from pushup sensors 88 and 90' t0 amplifier 86 are further compared with the feed back signal from sensor 92' which reflects the change in roll bending pressure from that desired and being requested by rheostat 74. When the algebraic sum of the signals from sensors 88', 90' and 92' and as transmitted by amplifier 86 substantially equate the feed back signal from sensor 82 to amplifier 76', no differentiating signal will be transmitted to amplifier 76 from amplifier 86 for further operating valve 80 and the roll bending load will be retained at that established by the setting of rheostat 74. Thus, sensors 92' and 82' in the circuit of FIG. 3 as in the case of

sensors

92 and 82 in the circuit of FIG. 2 perform a dual function in that they act as feed back devices for the roll bending actuators and at the same time as a means for comparing pushup pressures with bending roll pressures whereby any increase in pushup pressure which is adverse to the desired bending roll pressures is compensated for by increasing the roll bending pressures untilthe desired balance or proper equilibrium is established between roll bending and pushup pressures.

Further, the various embodiments of the instant invention can be used to advantage with other rolling mill instrumentations, such as specially designed work flattening control devices, computers, etc., to obtain the very optimum overall rolling conditions such as Where one mill stand equipped with the improvements of the instant invention is used alone and equipped with specially designed work flattening control devices or a series with other mill stands equipped with specially designed Wor-k flattening control devices. The invention is also applicable to mill stands comprised only of work rolls which have roll bending attachments and to mills used to roll other materials besides metal.

Advantageous embodiments of the invention have been shown and described. It is obvious to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope thereof, as set forth in the appended claims, wherein:

What is claimed is:

1. In a rolling mill apparatus including a framework and a pair of rolls rotatably and slidably mounted within said framework; a mill roll gap control system for said apparatus comprised of a roll pushup means including a first actuator operatively connected to said frame work and one of the rolls for applying selected pushup loads to said rolls and a first fluid circuit for said first actuator; a roll bending means including a second actuator operatively connected to a roll for applying bending loads thereto and a second independent fluid circuit for said second actuator; a first control means for controlling said first fluid circuit and for operating the actuator of said roll pushup means; a second control means for controlling said second fluid circuit and for operating the actuator of said roll bending means; means including electro-load sensing means interlocking said first and second control means, said first and second fluid circuit and said first and second actuators in an interdependent relationship whereby a predetermined actuation of one of said actuators can produce a preselected actuation of the other actuator in order to reestablish and maintain an established roll gap setting.

2. The apparatus as set forth in claim 1, including means for presetting one of said control means in order to initially establish a predetermined roll gap setting for a given rolling operation.

3. A mill roll gap control system for use with a rolling mill apparatus comprised of a framework, a pair of rolls and chock 'block means for rotatably and slidably mounting said rolls within said framework; said mill roll gap control system being comprised of a pushup means including a first actuator operatively connected to said framework and one of said rolls for applying selected pushup loads to said rolls in a direction transverse to the normal axis of said rolls; a first electro-control means operatively connected to said first actuator and including electrical signal transmitting means for adjusting said first actuator in accordance with an initially established roll gap setting when roll separating forces generated by a workpiece being rolled are applied to said rolls so as to reestablish and maintain the initially established roll gap setting; roll bending means, and a second electro-control means for said roll bending means and including an electrical signal transmitting means for adjusting the roll bending means in accordance with a desired roll bending condition;-and further electro-control means which operate in conjunction with said first and second electrical signal transmitting means of said first and second electro-control means to interlock said first and second electro-control means and to transmit electrical signals to said second actuator to effect adjustment in the roll bending means when the roll bending means is adversely affected by operation of said pushup means so as to maintain the initially established roll gap setting and there-by produce a final workpiece having a substantially uniform gauge across its entire width.

4. An integrated roll bending and roll pushup control system for a rolling :mill apparatus comprised of a framework and a pair of rolls rotatably and slidably mounted within said framework; said control system comprising a roll pushup means including a first actuator operatively connected to said framework and one of the rolls for establishing and maintaining a predetermined pushup load upon said rolls and a first fluid circuit for said first actuator; a roll bending means including a second actuator op eratively connected to a roll for applying bending loads thereto and a second independent fluid circuit for said second actuator; a first electro-control means for operating the fluid circuit for said pushup means; a second electrocontrol means for operating the fluid circuit for said roll bending means; means including electro-load sensin g means interlockingsaid first and second electro-control means and said actuators in an interdependent relationship whereby Whenever .a predetermined actuation of one of said actuators adversely affects the operation of the other actuator said other actuator will be further operated so as to bring one actuator into full balance with the other actuator.

5. A control system as set forth in claim 4 including means for presetting said first control means in accordance with a predetermined pushup load.

6. A system as set forth in claim 4, wherein the first electro-control means of said system includes a gauge rod and a load cell sensing element operatively connected to said pushup means.

7. A system as set forth in claim 4, wherein chock blocks are provided for one of the rolls and the first electro-control means of said system includes a gauge rod and a load cell sensing element operatively connected to said pushup means, the free end of the gauge rod being mounted so as to rest upon and be in selected pressure contact with one of said roll chock blocks whereby it is sensitive to a movement of said roll chock block in a direction generally normal to the axis of said chock block. I

8. A system as set forth in claim 4, wherein the rolling mill apparatus with which the system is associated includes backup and work rolls and said roll bending means is connected to the backup rolls.

9. A system as set forth in claim 4, wherein said electro-load sensing means includes a load feed back sensor for the first fluid circuit, a load feed back sensor for the second fluid circuit and an auxiliary summing amplifier connected to both of said load feed back sensors and to the actuator of said roll bending means.

10. A system as set forth in claim 4, wherein said electro-load sensing means includes an amplifier connected to said pushup means actuator, a load feed back sensor connected to said amplifier and to the roll bending means actuator, and a load feed back sensor also connected to said amplifier and said pushup means actuator.

11. A system as set forth in claim 4, wherein said electro-load sensing means includes a summing amplifier,

a load feed back sensor for the first fluid circuit, a load feed back sensor for the second fluid circuit and an auxiliary summing amplifier connected to both of said load sensors and to said summing amplifier.

12. A system as set forth in claim 4, wherein said electro-load sensing means includes a first summing amplifier connected to said pushup means actuator and a second summing amplifier connected to said roll bending means actuator, a load feed back sensor connected to said first named actuator and both of said summing amplifiers and a second load feed back sensor connected to said second named actuator and both of said summing amplifiers.

13. A system as set forth in claim 10, including means for transmitting an initial reference signal to said amplifier.

14. A system as set forth in claim 11 including means for transmitting an initial reference signal to said summing amplifier.

15. A rolling mill apparatus comprising a framework, a pair of rolls, chock blocks for rotatably and slidably mounting said rolls 'within said framework, pushup means including an actuator operatively connected to said framework and one of the chock blocks for applying pushup loads to one of said chock blocks and said rolls in a direction transverse to the normal axis of said rolls, control means operatively connected to said pushup means actuator and including a load cell for transmitting electrical signals to said pushup means actuator, a load cell rod connected to said load cell and having a free end adapted to rest upon and be in pressure contact with the top of the lowermost chock block of said chock blocks, said load cell rod also being mounted so as to be free of any pressure contact with another choc-k block, means for applying a predetermined pressure to said pushup means actuator and means interconnecting said load cell to said actuator pressure applying means whereby when a rolling load is applied to said mill apparatus by a workpiece and the load cell rods cease to be in pressure contact with the one chock block said load cell will operate to transmit a signal to the actuator pressure applying means of said pushup means actuator to move the said one chock block and return said one chock block into a selected pressure contact with the load cell rod.

16. An apparatus as set forth in claim 15 wherein said control means includes a summing amplifier for establishing a preselected load on said pushup means actuator and a feed back circuit from the load cell to the summing amplifier.

17. An apparatus as set forth in claim 15 wherein said control means includes a summing amplifier connected to said push-up means actuator, a rheostat for establishing a reference signal to said summing amplifier and a feed back circuit from the load cell to the summing amplifier.

References Cited UNITED STATES PATENTS 3,171,305 3/1965 Stone 72-241 3,250,105 5/ 1966 Stone 72240 3,280,610 10/ 1966 Qualey 72-245 3,318,124 5/ 196 7 Plaisted 72-8 3,327,508 6/ 1967 Brown 7 26 FOREIGN PATENTS 747 ,347 4/ 1956 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

A. RUDERMAN, Assistant Examiner.

US. Cl. X.R. 72-2l, 240, 245

Claims

1. IN A ROLLING MILL APPARATUS INCLUDING A FRAMEWORK AND A PAIR OF ROLLS ROTATABLY AND SLIDABLY MOUNTED WITHIN SAID FRAMEWORK; A MILL ROLL GAP CONTROL SYSTEM FOR SAID APPARATUS COMPRISED OF A ROLL PUSHUP MEANS INCLUDING A FIRST ACTUATOR OPERATIVELY CONNECTED TO SAID FRAME WORK AND ONE OF THE ROLLS FOR APPLYING SELECTED PUSHUP LOADS TO SAID ROLLS AND A FIRST FLUID CIRCUIT FOR SAID FIRST ACTUATOR; A ROLL BENDING MEANS INCLUDING A SECOND ACTUATOR OPERATIVELY CONNECTED TO A ROLL FOR APPLYING BENDING LOADS THERETO AND A SEONCD INDEPENDENT FLUID CIRCUIT FOR SAID SECOND ACTUATOR; A FIST CONTROL MEANS FOR CONTROLLING SAID FIRST FLUID CIRCUIT AND FOR OPERTING THE ACTUATOR OF SAID ROLL PUSHUP MEANS; A SECOND CONTROL MEANS FOR CONTROLLING SAID SECOND FLUID CIRCUIT AND FOR OPERATING THE ACUTATOR OF SAID ROLL BENDING MEANS; MEANS INCLUDING ELECTRO-LOAD SENSING MEANS INTERLOCKING SAID FIRST AND SECOND CONTROL MEANS, SAID FIRST AND SECOND FLUID CIRCUIT AND SAID FIRST AND SECOND ACTUATORS IN AN INTERDEPENDENT RELATIONSHIP WHEREBY A PREDETERMINED ACTUATION OF ONE OF SAID ACTUATORS CAN PRODUCE A PRESELECTED ACTUATION OF THE OTHER ACTUATOR IN ORDER TO REESTABLISH AND MAINTAIN AN ESTABLISHED ROLL GAP SETTING.