US2063810A - Rolling mill - Google Patents

Description

L. IVERSEN I ROLLING MILL Dec. 8, 1936.

Filed Jan. 24, 1934 5 Sheets-Sheet 1 INVENTOR Dec. 8, 1936.

L. IVERSEN ROLLING MILL INVENTOR L. IVERSEN Dec. 8, 1936.

ROLLING MILL Filed Jar}. '24, 1934 5 Sheets-Sheet 3 No WW 1 NM MW INVENTOR Patented Dec. 8, 1936 UNITED STATES ROLLING lVHLL Lorenz .Iversen, Pittsburgh, Pa.

assignor to Mesta Machine Company, Pittsburgh, Pa., a corporation of Pennsylvania 4 K Application January 24, 1934, Serial No. 708,097

9 Claims.

My invention relates to rolling mills and in particular to a vertical mill adapted to cooperate with the last stand of a continuous bar mill in the production of bars shaped and dimensioned to a high degree of precision.v

It is sometimes desired to give bars a pass through a stand of vertical rolls after passing the last stand of the usual grooved horizontal rolls, for precision sizing of the product. Vertical mills of this type heretofore have been driven from below by a line shaft through bevel gearing. This type of construction is heavy and cumbersome, and therefore diflicultrto assemble as well as to adjust and. maintain. The old construction has been objectionable also for the reason that it prevents the vertical mill from being placed close up to the last stand of horizontal rolls which is always desirable. The mechanical drive, furthermore, is inflexible as to ratio between diameters of the horizontal and vertical rolls to maintain a predetermined ratio between peripheral speeds which is always necessary, depending on the amount of reduction effected by the vertical rolls. Such drive also makes diflicult the removal of the mill when not needed.

Ihave invented a vertical mill of the char acter mentioned which overcomes the above recited objections to such devices as known heretcfore, and in addition is characterized by further novel and useful features which will become apparent as the description thereof proceeds.

In accordance with my invention, I provide a supporting base or frame in which are removably. and adjustably positioned a pair or roll units or housings each including a vertically adjustable roll shaft, a driving motor and powertransmission gearing. The construction is such that the vertical rolls may be positioned quite closely to the last stand of horizontal rolls. Provisions are made for easily efiecting all the desired adjustments of rolls and the individual motor drive makes it possible to'have the peripheral speed of the vertical rolls conform ex- .actly with that of the horizontal rolls, regardless ofany changes in the ratio of the roll diameters. The entire structure can readily be re,- moved when desired, since the drive is a-unit with the roll and its supporting housing.

My invention also contemplates an automatic control system for regulating the speed of the vertical rolls to maintain their peripheral speed exactly the same as that of the horizontal rolls.

To this end. I preferably employ synchronous alternating current motors for driving the verholder.

' tical rolls and I supply power to such motors from a generator driven by a variable speed motor. A regulator is effective to change the speed of the generator-driving motor in case the ratio of the speeds of the vertical and horizontal rolls 5 departs from a predetermined value.

For a complete understanding of the invention, reference is made to the accompanying drawings illustrating a present preferred embodiment. In the drawings- 1 Figure 1 is a side elevation of the vertical mill of my invention associated with a stand of horizontal rolls, specifically, the last stand of a continuous bar mill;

Figure 2 is a half section alongthe line 11-11 of Figure 1; I

Figure 3 is a sectional view along the line III--III of Figure 2;

Figure 4 is a partial sectional viewalong the line IV-JV of Figure 2; 20

Figure 5 is a schematic diagram showing the mill drive and the speed control apparatus; and

Figure 6 is a partial sectionalview along the line VIVI of Figure 3.

Referring in detail to the drawings, the last stand of a continuous bar mill is shown at Hi.

- of the base rest on a beam l8 supported on any convenient foundation.

Feet I9 on the other side of the base are bolted directly to the bed plate I? of the mill l0.

A pair of similar roll units 20 and 2| are slidably supported on the ways I 6 of the base l5. Each of these units comprises a generally boxlike casting 22 having a shelf 23 projecting out- 40 wardly thereof. Bearings 24 within the casting 22 support a worm wheel 25 coaxially thereof. The lower bearing 24 is held in position by a sleeve 26 telescoped into the lower end ofthe casting 22. The sleeve 26 is threadedinternally 45 to receive a bearing holder 21 correspondingly threaded. A thrust bearing 28 is seated in the holder '21 for supporting the lower end of a vertical shaft 29 therein. The bearing .28 is secured in the holder by a spur gear 3F b lted 'to the 50 The shaft 29 is 'splined to the worm wheel 25, permitting vertical movement of the shaft relative to the wheel. The upper end of the shaft .29 is journaled in a roller bearing 3|, which also 55 of the shaft 29 and roll 32 carried thereon. This adjustment can be effected by means of a shaft 35 projecting upwardly and outwardly from the lower part of the casting 22, and having a squared end for cooperation with a wrench. The shaft 35 carries a bevel pinion 36 at its lower end mesh-- ing with the gear 30 bolted to the holder 27.

The bottom of the casting 22 is closed by a cover 31 and an oil pump 38 on the lower end of the shaft 29 circulates oil from the cover, which serves as a reservoir, to all the working parts of the unit 29.

A motor 39 mounted on the shelf 23 drives a worm shaft lfl journaled in bearings 58a seated in the walls of the casting 22. It will be observed that the worm shaft ill] and the axis of the motor 3% are at an oblique angle to the path of material through the mill. This, permits the length of the mill in the direction of said path to be shortened and the entire construction made more compact. Both units are identical, furthermore, and are therefore interchangeable.

, The worm shaft til meshes with the worm wheel 25 and thereby drives the shaft 29 and the roll 32. It will be understood that the units 28 and 25 are identical as to the parts so far described.

The units 20 and 2i on opposite sides of the bearings 3! are provided with transverse bores 3i and t2 respectively. A tube 33 is seated in enlargements M of the bores All and t2. A screw shaft 5S5 extends through the bores and the tube. The end of the shaft is threaded for engagement with a nut 36 seated in the unit 28. A spring ll in the tube 33 is compressed between a ring 38 \bearing against the end of the enlargement of the bore ll, and a ring 6Q abutting a sleeve 58 bearing on the end of the enlargement of the bore d2. A collar 5! is threaded into the end of the tube l3. It will be apparent that the parts just described constitute a spring cushion for yieldingly forcing the units apart and that rotation of the shafts 55 will adjust the units toward or away from each other. The two screw shafts 45 on opposite sides of the bearings 53! may be simultaneously adjusted by means of a shaft 52, having a squared end for cooperating with a wrench, and a pinion 53. The pinion 53 meshes with gears 54 and these in turn mesh with gears 55 on the ends of the screw shafts t5.

The two units being adjustably held in a predetermined spaced relation relative one to another by the means just described, may be adjusted together laterally of the base so as to line up the pass between the rolls 32 with that between the horizontal rolls it. For this purpose I provide a screw shaft 56, the outer end of which is journaled in a thrust bearing 5i! at the end of the ways is on the exit side of the mill. An angle bar 58 shown more clearly in Figure 6 is bolted to the overhanging edge of the unit 2!. operation with the threaded portion of the shaft 56. The inner end of this shaft is journaled in a longitudinal bore through the way it. Rotation of the shmt dd applies lateral thrust ta the The bar 58 is threaded at 59 for 00-" unit 2i and thereby moves both units as an integral whole along the ways it. The end of the shaft 56 is squared for receiving a wrench to make this adjustment.

It has long. been known that vertical rolls for working bar stock must be driven at precisely the same peripheral speed in order to prevent lateral deflection of the bars as they emerge from the pass between the rolls. It is for this reason that vertical rolls have previously been driven from a common transverse drive shaft through suitable gearing, and introduced structural complications as before mentioned. By providing individual motor drives for both the rolls of the mill of my invention, I avoid the structural complications characteristic of the old mechanical drive and the necessity that the vertical roll diameters bear a fixed ratio to the diameters of the horizontal rolls determined by the ratio of the gearing therebetween. I preferably employ alternating-current motors of the induction type to drive the rolls at the same speed, the rolls being turned to precisely the same diameter. I supply the motors 39 with polyphase alternating current from a common source. The motors, being similar in design, operate in synchronism and the rolls 32 always turn at the same speed.

I utilize a special polyphase, alternatingcurrent generator as a source of current for the motors 3t and drive the generator by a variablespeed motor to make possible a highly flexible control of the speed of the rolls 32. The arrangement of the power apparatus and the control therefor are illustrated diagrammatically in Figure 5, wherein parts of mechanism which have already been mentioned have the same reference numerals used hereinabove.

Referring in detail to Figure 5, it will be seen that the motors 39 driving the vertical rolls 32 are connected in parallel to an alternating current generator Bil. The usual switches or circuit breakers are omitted from Figure 5, for the sake of clearness. The generator 60 is connected to a driving motor 63 preferably of the direct-current, compound-wound type, having a series field winding 52, a shunt field winding 53, a field rheostat B t and a speed-control resistor 65 connected in series with the shunt field winding. The motor 6i derives energy from a direct-current bus 66 through suitable circuit breakers not shown.

The rolls B3 are driven bya motor 61 which may conveniently be similar to the motor 6|, being of the usual compound-wound type with a shunt field rheostat for speed control. In the usual practice, the speed at which the motor 6'! drives the rolls l 3 is determined by the design of the mill as a whole, and is ordinarily not subject to material variation. For the purpose of coordinating the speed of the rolls 32 with that of the rolls I3, therefore, the speed of the rolls 83 may be assumed constant.

It will be obvious from the description already given that the control system of my invention makes it possible to vary the speed of the rolls 32 to provide the desired ratio to the speed of the rolls l3 by controlling the speed of the motor 6! through the shunt field rheostat 64. Any change in the speed of the motor 8! changes the frequency of the generator 60, and thereby, the speed of the motors 39. The system thus provides great flexibility of control of the speed of the vertical rolls. Regardless of the relative diameters of the vertical and horizontal rolls, it is only necessary to vary the speed of the motor 6! to drive the rolls 32 at the same peripheral speed as the rolls [3 or at a speed which bears a desired ratio to that of the rolls l3. Since the rolls 32 are always driven at the same speed, there can be I for accurate, continuous control of the speed of .To this end, I provide pilot generators the vertical rolls to overcome any slight departure of the ratio-between the speeds of the vertical horizontal rolls from the predetermined value. 68 and 69 connected to a synchroscope 10 or other equivalent device. The generator 68 is driven fromthe rolls l3. The generator 69 generator 60 through a hydraulic drive including a variable-displacement pump H and a simi lar motor 12 connected by a hydraulic circuit 13. The hydraulic drive is adjust-able and permits the speed of the generator 69 to be matched with that of the generator 68, regardless of the relative angular velocities of the rolls l3 and the rolls 32. The generators 68 and 69 have constant excitation and generate alternating voltages transverse drive shaft previously. is entirely eliminated, together with of frequencies directly proportional to the speeds at which they are driven. These frequencies may be equalized for a common peripheral speed of the rolls l3 and 32, by adjusting the hydraulic drive.

In order to insure that the surface speed of the vertical rolls is slightly greater than the surface speed of the horizontal rolls, it is-only necessary to speed up the motor 6| by field weakening until the synchroscope 10 revolves in the direction which indicates that the precision mill is running faster than the horizontal mill. There is thus no stubbing tendency when the piece enters the vertical mill. As soon as it enters, however, the load imposed on the vertical mill.will slow it down to a point where it is at the proper speed to receive the bar from the horizontal mill and deliver it at a speed as much higher as required by the ratio of reduction in the vertical stand.

It will be obvious that the invention described and illustrated herein is characterized by numei\ous advantages over anything known to the prior art. In the first place, the cumbersome which has been used its assembly, adjustment and maintenance difficulties. The vertical mill of my invention, furthermore, is adapted to be positioned very close to the last stand of a continuous mill, and in fact rests partly on the very foundation thereof. Each of the vertical rolls may be adjusted vertically with respect to the other to properly line up the grooves in the roll faces. The roll units, furthermore, may be adjusted toward and away from each other to provide the proper size of pass, and the two units shifted simultaneously in a single direction to line up the pass with that between the horizontal rolls. The means for effecting all these adjustments are simple, easily operable and readily accessible. These adjustments, furthermore, may be made so accurately that the mill may be correctly described as a precision machine. Since the rolls are overhung, thatis, both the shaft bearings are on the same side of the roll, roll changing is greatly expedited and facilitated. I

It is not necessary to clamp the parts in adjusted position since all adjustments are selflocking. At the same time, they can be operated with a minimum of effort. Each of the roll units is entirely self-contained and oil-tight, all

is driven from the] entire roll units themselves may be readily removed from the supporting base if this becomes necessary.

It is not necessary to disconnect the couplings, since the driving motors are mounted directly on shelves extend'ng laterally of the roll units.

There are no cross shafts, bevel gears, stuffing boxes or the like to require expensive and con tinuous maintenance. The, vertical rolls are electrically synchronized so that straight delivery of the material is insured. The entire unit may be lifted out when not required, as when rolling I products not requiring precision shaping and sizing. v 7

While I have illustrated and described but a single preferred embodiment of the invention, it will be apparent that many changes therein may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a rolling-mill, a base, a'pair of verticallydisposed, roll-shaft casings slidable horizontally thereon, a pair of spaced shaft bearings seated in an axial bore in each casing, means for resiliently forcing the casings apart, a tie rod extending through both the casings for limiting the separation therebetween, and means for adjusting one of said casings relative to the other.

2. In a rolling mill, a base, a pair of roll-shaft casings adjustable thereon, means extending through the casings to limit the separation therebetween, means between the casings for yieldingly urging them apart, and means for adjusting one of said casings along the base.

3. A rolling mill comprising a base, a pair of similar housings adjustably secured to the base, each housing including a shaft journalled substantially vertically therein, a roll mounted on the shaft, a shelf extending laterally from the housing, a motor mounted on the shelf with its axis substantially horizontal, and gearing providing driving connection between the motor and said shaft, the rolls of the two housings cooper-' ating to define a pass for material to be rolled/ each of said housings and its motor being removable from the base independently of the other.

4. The apparatus defined by claim 3 wherein said base is open at the top and said housings are suspended therein for removal vertically therefrom.

5. The apparatus defined by claim 3 characterized by means supporting said base, the base being removably secured to said means whereby the base and said units may be removed while maintaining a predetermined relation of the rolls and without-disconnecting the motors from their drives.

6. In a rolling mill adapted to cooperate with the last stand of a continuous mill driven at substantially constant speed, astand of finishing rolls adjacent said last stand, a variable speed drive for the finishing stand, means for indicating the relative peripheral speeds of the rollr of said last stand and said finishing stand, said indicating means including means driven at speeds proportional to those of the last stand and thereto, whereby to compensate said indicating means for variations in the diameters of the rolls of said stands.

7. In a rolling mill, a base, ways extending therealong, a pair of similar roll units adjustable on said ways, each of said units including a closed housing, a vertical roll shaft journaled therein, a shelf extending laterally from the housing, a motor mounted on the shelf with its axis horizontal, and Worm and Worm wheel driving gears between the motor and shaft, said housings being parallel, the drive and housing of each unit being independent of the other whereby either of said units is removable from said base independently of the other.

8. In a rolling mill, a base, a pair of similar roll-shaft housings carried on horizontal ways on the base for adjustment thereon, each housing having a laterally extending shelf, motors mounted on said shelves and disposed with their axes horizontal and oppositely inclined at an oblique angle to the path of material through the mill, a roll shaft journaled in each of said housings, one of said motors being geared to each shaft, said housings both being removable from the base independently of the other.

9. The apparatus defined by claim 3 characterized by each housing having a segmental nut secured thereto and a screw shaft journaled in said base cooperating with said nuts.

LORENZ IVERSEN.

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