US1620476A - Rolling mill - Google Patents

Description

March 8,1927.

L. LEE

ROLLING MILL Filed Aug. 1920 March 8, 1927. L. LEE

ROLLING MILL 3 Sheets-Sheet 2 Filed Aug. 1920 I I gwuentoz M @Hozneg L. LEE

ROLLING MILL March .8 1927.

Filed Aug. 1920 3 Sheets-Sheet s Patented Mar. 8, 1927.

UNITED STATES LEIF LEE, F YOUNGSTOWN, OHIO.

. ROLLING MILL.

Application filed August 30, 1920. Serial No. 406,946.

This invention has relation to certain new and useful improvements in rolling mills, and more particularly to mills for use in rolling steel sheets.

In mills of this character, several stands of rolls are usually connected in line, the first or roughing passes being performed on one set of rolls and the finishing passes on another set of rolls. The bottom roll of each 1 set is positively driven, all the bottom rolls being connected b couplings to form a continuous shaft. T e top rolls are usually not positively driven but are caused to rotate by the friction of the entering pieces, Consequently, the thickness of the piece is limited to that which willenter the rolls, In order to use a wider range in the thickness of the pieces and to insure that the pieces will enter the rolls quickly and surely,

several methods have heretofore been used for driving the top roll of the roughing rolls.

The present invention is designed to provide improved means of novel and efiicient character for driving the top roll of a sheetmill roughing stand, and which possess several important advantages, hereinafter pointed out, over the means heretofore employed for such purpose.

The nature of the invention and its mode of operation will best be understood by reference to the accompanying drawings, in which:

Figure 1 is an end view of a roughing stand having my invention applied thereto;

Figure 2 is a vertical section of one form of a reducing and slip gear which may be employed; and

Figure 3 is atop plan view of the portion of a sheet mill embodying my invention.

Figure 4 isv a partial sectional view approximately on line IVIV of Figure 2, the

ousing being omitted.

Figure 5 is an electrical diagram illustrating the connections for the induction motor.

In these drawings, 2 designates the bottom, and 3 the top roll of a sheet mill roughing stand, said rolls being mounted in any usual or suitable manner in the housings 4. 5 is the top roll of an adjacent finishing roll stand. 6 desi nates an electric motor mounted at the en of the rougher. This motor drives a worm 7 which meshes with a worm wheel 8, loosely mounted on a shaft 9, said v2 and 4 herein. That device comprises a hub 14 loosely mounted on the shaft 9 and to which the worm gear 8 is bolted. A member havin an annular flange 15 is alsoi bolted to t e hub 14. The flange 15 is provided with a lurality of equally spaced grooves 16, as s own in Figure 4. A memer 10 is keyed to the shaft 9 and has two diametrically opposite arms. Levers 17 are pivotally mounted on the arms of the member 10, as shown in Fi re 4. In one end of each of the levers 1 is placed a roller 18 which engages the grooves 16 in the flange 15. To the other end of each of the levers 17 is pivotally connected a rod 19. The two levers and their connecting means are identical, and therefore a description of one will be sufiicient' for both. A' spring 20 surrounds the rod 19, and one end of the spring 20 engages a housing 21 on the member 10. The other end of the spring 20 engages a collar 22 which is held in place on the rod 19 by the nuts 23. The tension of the spring 20 may be changed to chan e the pressure of the rollers 18 against t e flange 15. The flange 15' is positivel driven by the worm 7, and drives the sha 9 through the rollers 18 and member 10. If the resistance to the shaft 9 is suflicient to cause the rollers to ride out of the grooves 16, the flange 15 may rotate relative to the shaft 9. If that resistance is not great enough to cause this relative movement, the shaft 9 is driven at the same speed as the flange 15. 11 designates a suitable housin for the reducing and slip gear. The sha t 9 is connectedto the top roll 3 by means of the short shaft 12 and the universal joints 13. The joints 13 are rovided in order to take care of varying distances between the centers of. the rolls 2 and 3. An arrangement for automatically controlling the motor is shown in Figure 5. The wires 24 lead from the rotor of the motor 6 to resistances 25 and 26. These wires in passing to the resistances include solenoid coils 27 arranged on a core 28. An armature 29 is arran ed above the core 28 and is adapted to be pul ed down by the coils 27 upon the passing of a predetermined current through the coils 27. The armature 29 is normally held in the position shown by a spring 30. A switch member 31 is pivoted at 32, and a link 33 connects the switch member 31 with the armature 29 so that when the parts are in the position shown a circuit is closed through the wires 34. This circuit 34 includes the solenoids 35, which act upon switch members 36 to hold circuits closed through the contacts 37 and 38. When the contacts 37 and 38 are closed, the resistance sections 26 are short-circuited. When the coils 35 are de-energized, the switch members 36 rest against the stops 39. The circuit of the coils 35 is controlled by the switch member 31, which in turn is controlled by the current in the rotor windings of the motor. The

operation of the arrangement shown is as follows:

The top roll 3 is so geared as to run at a speed slightly below that of the bottom roll 2. Whenthe steel starts between the rolls, it frequently sticks during the biting period. This causes the to roll 3 to slow down, greatly increasing t e load on the motor 6. The load on the motor increases from that required to overcome the friction of the top roll to that required to roll the steel through the 'biting period includin friction. After the steel is between the re ls, the top roll is driven by friction through the steel from he lower roll at a higher speed than the normal speed of the motor 6, and the motor 6 is therefore relieved of load.

I prefer to employ for the motor 6 an alternating current motor of the wound rotor type with a gear reduction such as to run the top roll 3 at a slightly lower speed than the bottom roll. As above stated, after the steel has entered the rolls, the top roll will speed up above the synchronous speed of the motor. This will relieve the motor of load, and will cause the generation of a small amount of pgwer in the motor; but this power will not sufficient to substantially load the driving means for the lower roll.

The slip gear is so adjusted as to operate upon the occurrence of a predetermined overload, and acts independently of the electrical control means for the motor, and its tendency is to definitely relieve the motor upon the occurrence of the predetermined overload in either direction.

When the load on the motor 6 increases to a predetermined amount which is below the load, causing the slip gear to operate, the solenoid 27 .will draw the armature 29 downwardly and cut the resistances 26 into the armature circuit of the motor. This will decrease the speed of the motor and protect its windings against damage, but the motor will continue to operate at its lower speed and cause the steel to continue to move between the rolls. As soon as the steel passes the biting period, the top roll will be speeded up, thus relieving the load on the motor, whereupon the armature 29 will be raised and the resistances 26 cut out of the motor armature circuit. From the foregoing, it is therefore evident that means are provided for positively operating the top roll throughout the biting period, as well as means for protecting the motor against damage by heavy current flow. The slip gear is also provided for protecting the motor when the load exceeds a predetermined maximum.

The construction disclosed herein, besides being desirable by reason of certain of the mechanical features employed, is of mate rial advantage by reason of the fact that it keeps the two adjacent roll stands close enough so that the distance between the rolls of the respective stands permits work to be transferred from one stand to the other in a single throw by a single operator. This-is highly desirable, as union rules in force at the present time require two men where the distance is increased beyond a certain limit. In such cases the mill is referred to as a double throw mill.

My invention provides an extremely simple and effective to roll drive in a mill of the character descri ed, since it gives the necessary range for thickness, and insures the proper and quick entry of the work piece, while relieving the auxiliary motor from actual work in rolling.

I do not limit myself to the particular embodiment of my invention which I have herein shown and described, as many changes may be made therein within the s irit and 'scope of the appended claims.

hus, any suitable form of auxiliary motor may be used; the type of reducing gearing may be changed, and any suitable adjustable means for permitting slip between the motor and the top roll at any torque above the safe motor torque may be employed.

. I claim:

1. In a rolling mill, the combination with a pair of rolls, of an electric motor for driving one of said rolls independently of the drive for the other of said rolls, and gearing connecting said motor with the shaft of the roll driven thereby, said motor and gearin being arranged to normally drive said rol at a lower speed than the other roll, said gearing including. slip means whereby, when a workpiece enters the rolls and thereby causes the speeding up of said motordriven roll, said motor will be normally driven by said roll above the normal speed of said motor, said slip means being constructed to operate upon the occurrence of a predetermined overload on said motor, substantially as described.

2. In a rolling mill,.the combination with a pair of rolls, of an electric motor for driving one of said rolls independently of the drive for the other of said rolls, and gearing connecting said motor with the shaft of the roll driven thereby, said motor and gearing being arranged to normally drive said roll at a lower speed than the other roll, said gearin including slip means whereby, when a wor piece enters the rollsand thereby causes the speeding up of said motordriven roll, said motor will be normally driven by said roll'above the normal speed of said motor, said slipmeans being constructed to operate upon the occurrence of a predetermined overload on said motor and being adjustable to operate at different overloads.

3. In a rolling mill, the combination with a pair of rolls, of means partly offset laterally withrespect to the rolls for driving one of said rolls independently of .the drive for the other of said rolls, said means'comprising an electric motor and a slip gear or clutch between the motor and roll shaft designed to slip in the direction of drive'upon the occurrence of a predetermined overload on the motor, substantially as described.

4. In a rolling mill, the combination with a'pair of rolls, of means for driving one of said rolls independently of the drive for the other of said rolls, said means comprising an electric motor ofi'set laterally with respect to the rolls and a slip gear or clutch between the motor and roll shaft designed to slip in the direction of drive upon the occurrence of a predetermined overload on the motor and being adjustable to operate at different overloads, substantially as described.

The combination with a two-high sheet rolling mill stand having a drive for its bottom roll, of a separate alternating cur-- rent motor drive for the top roll, said drive having means whereby an entering workpiece will drive the top roll at a higher speed than the synchronous speed of the motor and thereby relieve said motor of rolling load, substantially as described. I 6. The combination with a two-high shee rolling mill stand having a drive for its bottom roll, of a separate motor drive for the top roll, said drive comprising an alternating current motor, and means for affect-- ing the circuit of said motor to cause its 7 speed to be reduced when a workpiece enters ranged to vary the resistance in the rotor circuit upon increase in current pulled by the motor when the workpiece enters the of rolling load, said motor having its arma-- ture shaft at substantially right angles to the axes of the rolls, substantially as described.

9. The combination with a two-high sheet rolling mill stand having a drive for its bottom roll, of a separate motor coupled to the top roll to continuously drive the same until the workpiece has entered the rolls, together with means for causing the said motor to automatically slow down when a work piece enters the rolls, the slowing down of the motor being dependent upon the difficulty encountered by the workpiece in entering between the rolls, substantially as described. I

10. The combination with a roughing mill, of a finishing mill, said mills having their rolls in end to end relationship, and means intermediate the mills but ofiset laterally relatively thereto to drive the top roll of the roughing mill while maintaining a single throw distance between the mills, substantially as described.

11. The combination with a roughing mill, of a finishing mill, said mills having their rolls in end to end relationship, and an electric motor intermediate the mills but ofiset laterally relatively thereto to drive the top rolls of the roughing mills, while maintaining a single throw distance between the mills, substantially as described.

12. The combination with a roughing mill, of a finishing mill, said mills having their rolls in end to end relationship, and means intermediate the mills but offset laterally relatively thereto to drive the top roll of the roughing mill while maintaining a single throw distance between the mills, said means having a slip gear connection with the roll it drives, substantially as described.

13. The combination with a roughing mill, of a finishing mill, said mills having their rolls in end to end relationship and having a single throw distance between the respec tive passes of the mills, a gear reduction intermediate the mills and operatively connected to the top roll of one of the mills, and means oflset laterally relatively to the gear reduction and mills for driving the gearreduction, substantially as described.

14. The combination with a roughing mill, of a finishing mill, said mills having their rolls in end to end relationship and having a single throw distance between the rcspective passes of the mills, a gear reduction intermediate the mills and operatively connected to the top roll of one of the mills, and means offset laterally relatively to the 5 gear reduction and mills for driving the gear reduction, said means comprising an electric motor operative for' driving the top roll at a lower speed than that at which the bottom roll is driven, substantially as described.

In testimony whereof; I have hereunto set my hand.

I \LEIF LEE.

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