US2629272A

US2629272A - Rolling mill control

Info

Publication number: US2629272A
Application number: US759786A
Authority: US
Inventors: Frank J Wood
Original assignee: ERWIN LOEWY
Current assignee: ERWIN LOEWY
Priority date: 1947-07-09
Filing date: 1947-07-09
Publication date: 1953-02-24
Anticipated expiration: 1970-02-24
Also published as: FR1020329A; GB650412A

Description

IN VEN TOR.

Feb. 24, 1953 F. J. WOOD ROLLING MILL CONTROL Filed July 9, 1947 2 SHEETSSHEE A TTORNEYS FRANK J. WOOD mm 3 i J m I S A lllllu aw QH\H I 3. mm mil 1 5 S .\S 6mm Z2 MM W W Feb. 24, 1953 F. J. WOOD ROLLING MILL. CONTROL 2 SHEETSSHEET 2 Filed July 9, 1.947

w 0 m0 V0 w J K M y B s [M A TTOPIVEYS i atented Feb. 24, i953 ROLLING MILL CONTROL Frank J. Wood, New Rochelle, N. Y., assignor to Erwin Loewy, New York, N. Y.

Application July 9, 1947, Serial N 0. 759,786

3 Claims.

This invention relates to rolling mill-s and particularly to a drive and control for a four-high rolling of thin metals, such as metal foil.

A rolling mill is an expensive machine, and,

therefore, it is desirable to be able to increase the productivity thereof whenever possible, and particularly, when a low cost item, such as foil, is being rolled, the greater the quantity of foil produced by a mill, the greater the reduction in cost of the foil. Also, by speeding up the rolling mill, one mill can perform the task of several mills. The standard speed now 'in use for foil mills is about 400 feet per minute. By the use of the invention described herein, this speed can be increased to as much as 3,000 feet per minute whichwill give a significant increase in output of a mill.

One of the principal objects of the invention is to materially increase the speed of operation of a rolling mill.

Another of the objects of the invention is to produce a smoother and more perfect product at the aforementioned high operating speeds of a rolling mill.

Another object of the invention is a simplified manner of controlling the acceleration, deceleration, and operation of a rolling mill.

In prior practice, rolling mills of the four-high type have been driven through the outer rolls alone, the inner rolls alone, or by an interconnection or driveof all four rolls. It has been found, however, that these arrangements are not entirely satisfactory. At high speeds of operation, an imperfect product will be rolled, particularly in thin material where the thickness of the material is in the range of 0.00025 of an inch. When a rolling mill is operated, the backing roll is made considerably larger in diameter than the work roll, the ratiosof the diameters being, for example, two or more to one. There-is a thin film of lubrication normally on-the rolls, the coefficient of friction between rolls is small, and there is substantially only a, line contact between the'rolls. In the acceleration of the rolls up to speed, it is thus apparent that the force between the rolls is along a line contact and that the coefficient of friction is small and thus the rolls will tendto slip relative to each other, it being remembered that the moment of inertia of the rolls varies as the square of the radius thereof. When the back-up rolls are accelerated and decelerated by friction from the work rolls, skidding of the work roll against the large mass of the back-up roll will scratch the highly finished surface of the work rolls. It is necessary, therefore, due to the large inertia of the back-up roll, to drive the back-up roll during acceleration and deceleration in high speed operation. Difficulty arises when the speed of the work roll is changed during the rolling operation because there will be a skidding action between the backing and the work rolls and this will tend to scratch or roughen the work roll surface. On thin gauge material, the depth of the scratch or roughening of the roll often will represent a substantial propor tion of the thickness of the foil to be rolled and thus will mark the foil and also may cause breakage. Attempts have been made to minimize the slip or skidding by using excessive pressure between the rolls, but this results in many problems.

When the rolls .are all connected together and driven simultaneously by gearing, difi'iculty is involved at high speeds due to the unequal roll diameters. One of the features of the present invention is to drive all four rolls during the acceleration period and then to drive only the work rolls during rolling. A friction type clutch is provided in the drive connections to the two back-up rolls, the clutch being engaged during the accelerating period and then disengaged when the mill reaches its operating speed.

Another feature of the invention is to reconnect the back-up rolls to the drive mechanism as the rolling mill is decelerated to a stop. In one aspect of the invention, an electrically operated clutch is used although a suitable mechanically operated clutch also may be employed.

These and other objects, features, and advantages of "the invention will become apparent from the following description and drawings which are merely exemplary.

Fig. 1 shows a schematic front view of the rolling mill with the drive mechanism of the present invention.

Fig. 2 shows a wiring diagram of one type of control that may beused.

Fig. 3 is an enlarged diagrammatic view of the gagrietic clutch used in the arrangement of Fig. 4 is an enlarged view of a mechanically operated clutch that can be used in place of the clutch of Fig. 3.

Fig. dis a fragmentary view of Fig. 2 showing the control generator replaced by a fly-ball generator.

In the preferred form of the invention, the rolling mill stand is indicated diagrammatically at I 0 having housings ll supporting the bear- 53 is'pressed. This will open the holding circuit to the main switch solenoid 45 and thereby cause main switch 46 to open, thus de-energizing drive motor I6. Contacts I3 of the stop button will be closed which will complete a circuit through the decelerating magnetic clutch switch solenoid I6, the circuit being completed from lead H2 through lead H3, closed switch contacts 54, closed switch contacts I3, lead H4, solenoid I6, lead H5 and lead I09. This will cause energization of the decelerating magnetic clutch solenoid and close the decelerating magnetic clutch switch TI. The holding switch contacts I8 also will be closed to provide a holding circuit around the stop button contacts I3, the holding circuit being established from lead H2, switch contacts 54, lead H6, switch 18, lead I", lead H4, solenoid I6, lead H5, and lead I09. The solenoid 55, during this operation, still remain in energized position so that the main magnetic clutch switch 56 remains closed. Operation of the solenoid I6 will thus re-energize magnetic switch clutch coil I I I so as to positively reconnect the backing rolls and the working rolls during deceleration. As the rolling mill slows down, switch 59 also will close providing two paths to the magnetic clutch coil III.

In order to de-energize the entire circuit, it is necessary to operate the reset push button H which will de-energize the magnetic clutch switch solenoid 55 and thus de-energize the magnetic clutch III and the decelerating magnetic clutch solenoid 16.

A flyball governor arrangement 19 (Fig. 5) can be driven by a suitable connection 63 with the main drive motor operating shaft. The flyball governor 19 may be connected to a switch arrangement 80 which will govern the energization of magnetic clutch solenoid 82 by a source of energy 8I. Thus, when the drive motor I6 reaches operating speed, switch 80 will close and source of energy 8I will cause opening of switch 83, switch 83 being identical to switch 59 in Fig. 2 and serving to de-energize the magnetic clutch III and thereby interrupt the positive drive of the backing rolls.

The power supply source is shown diagrammatically at 84 in Fig. 1 with the control box 85 containing the electrical circuits involved, the drive control generator corresponding to 62 of Fig. 2 being shown in box 86. The push buttons are shown diagrammatically connected to the control box 85 and are operable, as just described, to start, stop, and reset the control circuit.

When the machine is to be operated, it is first brought up to speed by pressing start button 44. This will cause drive motor I6 to b energized and all of the rolls to be driven as the speed thereof is accelerated. As explained previously, thi is necessary or desirable because of the inertia of the rolls, which is particularly significant at the high operating speeds of the device. After the device has reached the desired operating speed, the clutches 30 and 3| will disconnect the positive drive or direct application of torque to the backing rolls and thus only the work rolls will be positively driven. The rolling mill then is in condition for carrying out rolling operations. A explained previously, the relative inertias of the large size backingrolls and the working rolls is such that skidding is liable to occur during high speed rolling operation, and by the use of the hereindescribed system and method of operation of the mill, previously known serious difliculties of high speed operation, espe- B, cially when rolling thin material, are eliminated.

When it is desired to decelerate the rolling mill or bring it to a, stop, pressing of push button 53 will cause the clutches to reconnect the backing rolls with the driving gear and, at the same time, will cut off the driving power to the gear drive, thus serving to rapidly decelerate all of the ro ls together. If the reconnection was not made, the large inertia in the backing rolls might cause serious difficulties in the roll operation due to slippage between the backing rolls and the working rolls during deceleration.

The particular control system used for governing operation of the mill can be carried. out by various circuits, and various types of clutches can be used, it being understood that thoseshown herein are, merely exemplary. It is thus apparent that the details of construction depicted and described may be varied without departing from the spirit of the invention as defined in the appended claims.

What is claimed:

1. In a control system for a rolling mill having working and backing rolls, the working and backing rolls being in frictional contact with each other, material being passable between said working rolls, a switch shiftable to energize a driving motor, said driving motor being positively connected to said working rolls, clutch mechanism connecting the driving motor with said backing rolls, a second switch mechanism operable when said first switch mechanism is shifted to activate said clutch mechanism and connect said drive mechanism positively to said backing rolls, and a roll speed switch mechanism connected with said second switch mechanism operable when said rolls have reached a predetermined speed deactivating said clutch mechanism and interrupting the positive connection of said driving mechanism to said backing rolls, so that said backing rolls then are driven only by frictional contact with their respective working rolls.

2. In a control system for a rolling mill having working and backing rolls, the working and backing rolls being in frictional contact with each other, material being passable between said working rolls, a switch shiftable to energize a driving motor, said driving motor being positively connected to said working rolls, normally deactivated clutch means connecting said driving motor with both of said backing rolls, a second switch mechanism operable when said first switch mechanism is shifted, activating said clutch means to connect said drive mechanism positively to said backing rolls, a roll speed switch mechainsm connected with said second switch mechanism operable when said rolls have reached a predetermined speed deactivating said clutch means and interrupting the positive connection of said driving mechanism to both of the backing rolls so that the backing rolls are driven I only by frictional contact with said working rolls,

and a stop switch connected with said second switch mechanism and operable to reactivate said clutch means to reconnect said drive mechanism to both of said backing rolls and to interrupt the energization of said drive motor.

3. In a high speed four high rolling mill suitable for rolling thin foil or the like, said mill havmg working and backing rolls, the working and backing rolls being frictionally contactable with each other, working roll driving mechanism connected with both of said working rolls at all times during rolling, selectively operable driving clutch means connnectable with said backing v i 1- s' rollsroniyi'duringtaccelerationiandstoppmgofithe said zbackmgznolls, zarewdrivenzonly by :irictional. mill {or positively "connecting said backing rolls contact withihe'working 1011s. to said driving mechanism, said backing rolls \be- FRANK =J.' ing driven'at other times by frictional contact withth-eir working rolls control'means connected REFERENCES CITED to said-clutch means and having mechanismo The following references are of recordrin .athe erable during acceleration to activate said clutch file of "th s Patent! means and connect said backing rolls to said UNITED sTATESPATENI-s drivingmechan'ism and having mechanism operable'when the mill is *to be stopped to activate 10 gigg P Name A 3 said clutch-means'and-connect said-backing rolls 1 figg 1922 to said driving mechanism. andspeed responsive Hem 1925 means oonnectedwith said control means interruptingvactivation of said clutch connection of V FOREIGN'TPATENTS said backing vrOllsizosaid drivingmechanism when 15 Number Country Date they have reached'a pre-determined speed, so that 606301 Germany 1 Nov. 29,1934