US1267184A

US1267184A - System of control for tandem rolling-mills and the like.

Info

Publication number: US1267184A
Application number: US71643512A
Authority: US
Inventors: Walter R Clark
Original assignee: Bridgeport Brass Co
Current assignee: Bridgeport Brass Co
Priority date: 1912-08-22
Filing date: 1912-08-22
Publication date: 1918-05-21
Anticipated expiration: 1935-05-21

Description

W. R. CLARK.

SYSTEM OF CONTROL FOR TANDEM ROLLING MILLS AND '[HE LIKE APPLICATION FILED 16.22. I912.

1,267,184. Patented May 21, 1918.

2 SHETSSHEET I.

WITNESSES:

1N VEN TOR.

W. R. CLARK.

SYSTEM OF CONTROL FOR TANDEM HQLLING MILLS AND THE LIKE.

APPLICATION FILED AUG-22.1912.

1 ,26'7, 1 84:. Patented May 21, 1918.

I 2 SHEETS-SHEET 2- /7 .4. 20

IVITNESSES:

7/f W'y [.VVENTOR.

A TTORNEKP,

UNITED STATES PATENT OFFICE.

WALTER B. CLARK, 0F BRIDGEPOBT, CONNECTICUT, ASSIGNOR T0 BRIDGEPORT BRASS COMPANY, OF BRIDGEPORT, CONNECTICUT, A CORPORATION OF CONNECTICUT.

l SYSTEM OF CONTROL FOR TANDEM ROLLING-MILLS AND THE LIKE.

Specification of Letters Patent.

Patented May 21, 1918.

Application filed August 22, 1912. Serial at. 716,435.

To all whom it ma concern:

Be it known tiat I, WALTER R. CLARK, a citizen of the United States, residin in Bridgeport, county of Fairfield, and tate of Connecticut, have invented certain new and useful Improvements in Systems of Control for Tandem Rolling-Mills and the like, of which the following is a full, clear, and exact description.

This invention relates to a system of controlling the relative speeds of rolling mills or similar metal working devices arranged in tandem, where the bar or sheet is acted on by the respective devices simultaneous y. The improved system is especially applicable to tandem mills for rolling material of medium and heavy gage, so heavy in fact, that a considerable tension may be put u on the rolled bar, in addition to that exerte by a pair-of rolls in rolling it, without strainin it beyond its elastic limit.

eretofore, in rolling sheets or bars of brass or other metal by means of individually driven tandein mills, it has been customary to rely solel on manual control of the speed of the in ividual mills. For example, if two individually driven stands of rolls are arranged in tandem fashion, to successively reduce the bar or sheet, it is usual merely to provide hand operated speed controlling devices whereby the operator may regulate individually the speed of the respective prime movers or motors driving the respective mills. Where this manual control is the onl one provided, however, considerable di culty is encountered in distributin properl the total work of reduction of t e metal etween the individual pairs of rolls. For instance, if one of the mills slows down from any external cause, or if it speeds u or slows down as a result of a change in t e gage of the material bein rolled due to the expansion of the rolls or 518.111 spots in the metal, or other causes, it is a very difiicultmatter, in fact practically impossible, to control manually the speed of the other mill in consonance with the irregular speed variations of the first named mill. Hence it follows, that in such a system of control the distribution of work is very uneven, the tension of the material passing from one mill to the other fluctuates considerably, and is usually either or other devices are controlled automatically.

In other words, my improved system of speed control provides for an automatic adjustment of the speed of one mill as the speed of the other varies, so as to compensate entirely for the relative speed variatlons of the mills with reference to the distribution between the latter of the total work of reduci tion. each performs a certain proportion of the total work, the ratio of the output of the respective mills will be maintained automatically in spite of external influences and in Sliltfl of variations in the gage of the meta rolled.

To these and other ends the invention consists in the novel system of speed control to be hereinafter described and claimed.

In the accompanying drawings,

Figure 1 is a side elevation of a rolling mill installation embodying my invention, the respective stands of rolls being driven by electric motors,

Fig. 2 is a top plan view of Fig. 1,

Fig. 3 is a diagram of the motor of one of the stands,

Fi shows in elevation a tandem rolling mill installation in which the respective mills are operated by steam engines,

Fig. 5 is' a to plan view of Fig. 4, and

Fig. 6 is a etail of the governor of one of the engines.

The improved system is applicable to rolling mills driven by electric motors, steam engines, internal combustion en 'nes, and other motors or rime movers. e general principles are tli e same in each case, and I ave only selected for illustration, embodiments in which electric motors and steam engines, res ectively, are employed for drivin the m' a y eferring to Figs. 1 to 3, showing the electric motor arrangement or embodiment, A and B indicate stands of rolls to act simultaneously on successive portions of a bar or sheet of metal C passing from the mill A to Hence if the mills are adjusted so that the mill B, as indicated by the arrows. The mill A first acts on the bar or sheet and reduces it to a certain extent, and the reduced portion of the bar passes forwardly to be further reduced by the mill B which is arranged in advance of the mill A as regards the direction of feed. The mill or stand A is driven b means of an electric motor 10 geared to t e rolls in any suitable manner and the mill B is similarly driven by means of an electric motor 11. The speed of the motor 10 is controlled manually by a controller or rheostat 15 and the motor 11 is similarly controlled by a rheostat 12.

In the embodiment illustrated, the motor 11 is intended to represent a shunt wound motor operating at a substantially constant speed under fluctuating loads. On the other hand, the motor 10 for driving the mill A is so wound, as distinguished from the shunt motor 11, as to decrease in speed and increase in torque in proportion to an increase in the load, and vice versa. In other words, the motor 11 for the mill B is practically a constant speed motor, while the motor 10 of the mill A varies in speed inversely in proportion to the load. In order to give the motor 10 the characteristics above noted, I use by preference :1 compound winding, as shown in Fig. 3, where the armature is indicated at 13 and the field at 14. The field 14 comprises a shunt windin 14 and a series winding 14!, the shunt w nding 14 being connected with the rheostat 15 by means of which the speed of the motor 10 may be varied by the operator. I prefer, in actual practice, to have the normal shunt winding 14E constitute about per cent. of the total field winding, in which case the series winding 14 will only amount to about 20 per cent By this arrangement the motor retains practically all of the shunt motor characteristics which adapt it particularly for driving a stand of rolls, and yet the series portion of the field is sufficient to cause enough speed variation in proportion to the load to efi'ect the operation now to be described.

Supposing the bar or sheet of brass or other metal to be passing from the mill A to the mill B, so that it is successively reduced by the respective pairs of rolls, the mill B will be driven at a practically constant speed, which is preferably so adjusted "with respect to the speed of the mill A, that the mill B pulls the sheet or bar through the rolls of the mill A to a slight extent, thereby assisting to a certain extent in theoperation of the mill A and relieving the motor 10 of a corresponding amount of work. If now the mill B be slowed down, for example, by -any external influence, or by a decrease in the thickness of the bar or sheet due to expansion of its rolls or hard spots in the metal, the pulling efl'ect of the mill B on the bar or sheet passing between the rolls of the mill A will be correspondingly decreased. This will obviously put more work on the motor 10 of the stand A, and accordingly, the influence of the series winding 14 of said motor will be immediately called into play, with the result that the speed of the motor 10 will decrease approximately in proportion to the increase of load produced by the decrease of speed of the mill B. Hence it will be understood that the decrease of speed of the mill B will be immediately followed by a substantially corresponding decrease of speed of the mill A, the latter adapting itself automatically to the speed decrease of the mill B in such a manner as to maintain the ratio of the reduction done by the two mills. Supposing that the speed of the mill B be increased for any cause, the pulling'efiect of this mill on the bar or sheet passing through the mill A will, of course, be correspondingly increased, thereby further relieving the motor 10, and as the load on the latter decreases the efl'erl of the series winding 14 is immediately tn produce a corresponding increase of speed to compensate for the increase of speed of the mill B.

If at any time the mill A tends to roll the bar faster than the mill B can carry it, the former, mill will tend to push the bar through the latter, thereby relieving the mill B of some of its work until the mill A has slowed down on an equilibrium point.

It is not necessary in all cases that the. mill B be driven by an electric motor, as it might be driven by other means while still retaining the electric drive of the mill A. On the other hand, it is not always essential that the variable speed characteristics mentioned above in reference to the mill A be limited to said mill, as obviously an interchange of the

driving motors

10 and 11 as between the mills A and B would be within the broad aspects of my invention. In other .words, it mightbe practicable in some cases to have the mill A driven by a constant speed motor and to have the mill B driven by a variable s eed motor.

In Figs. 4 to 6 inclhsive, the relative arrangement of the mills A and B is substantially the same as that previously described, but the mill A is driven by a steam en ine 16 and the mill B by a steamengine l7. The engine 17 is rovided with a governor 18 connected witih the throttle. valve 19 (or otherwise arranged) so. asto. maint In a practically constant speed of the engine 17 and mill B under varying conditions of load. This means 01, speed control by means of a fly-ball governor-is .a very common one, and hence need-not be described in detailr In order to provide for the variable speed characteristics of the engine 16 the action of the ball governor 20 thereof (connected with the throttle valve 21 by means of the link 22) is opposed by a spring 23 which prevents the governor from operating the throttle valve sufficiently to compensate for variations of load, so that the speed of the engine 16 will decrease as the load increases, and vice versa. In the embodiment shown, the governor 20 comprises the usual centrifugally acting balls 24 acting on the usual sliding sleeve 25 to which is connected one end of a bell crank lever 26 pivoted to a fixed part 27 and suitably connected with the throttle controlling link or rod 22. As the balls are lowered by a decrease of speed (due to an increase of load) they tend to carry downward the collar 25 and to so actuate the valve rod 22 as to bring the speed again up to the normal, but this tendency of the fly-balls 24 is opposed by the sprin 22, interposed between the standard 28 and the free extremity of the bell crank lever 26, so that the compensating effect of the governor is offset to a degree, with the result that changes of load will cause corresponding but inverse changes of s eed.

As the speed characteristics of

t e engines

16 and 17 are substantially the same as those of the

motors

10 and 11 heretofore described, it will be obvious that the operation of the installation now being described, will be substantially the same as that of the first installation. Moreover, it will be manifest that the invention can be carried out in substantially the same manner with as engines or other prime movers having the characteristics above described. It is not necessary, in all cases, that the rime movers or motors of the respective mills or other metal working devices have different speed and torque characteristics, so long as at least one of the motors changes its speed automatically with a change of load.

f course, I do not wish to limit myself in all of the various aspects of my invention, to the application of the present system to the tandem rolling of sheets or bars. I have used the term rolling mill in a broad sense intending to cover such an equivalent device as a wire drawing block or other apparatus. It is, moreover, evident that the invention is not limited to the use of two metal working devices arranged in tandem, as a larger number may be grouped together in some cases. Various changes in these and other respects may be adopted within the see c of the appended claims.

hat'I claim is:

1. In a tandem rolling mill installation the combination with the respective mills, o a separate prime mover for driving each of the same, and means controlled directly by variations of tension in the stock between the mills, independently of variations of length incident to such tension changes, for automatically varying the speed of i the prime mover of one mill, to com ensate for speed variations of the other m1 substantially as described.

2. The combination of metal working de vices arranged in tandem for simultaneous operation on a length of stock fed by one of said devices to the other, separate prime movers for said devices, and means controlled by the direct action of the stock on one of said devices due to variations of tension in that portion of the stock between said devices, and independently of changes of length in such portion incident to such tension changes, for automatically and directly varying the speed of one of said devices to compensate for the speed changes of the other.

3. The combination with metal reduction devices arranged in tandem for simultaneous action on successive portions of a length of stock, of individual prime movers to drive the res ective devices, one of said prime movers eing adapted to so operate the correspondin meta reducing device that it will pull t e stock through the other metal working device, and at least one of said rime movers being constructed to decrease in speed with an increase of load caused directly by a chan e of tension in that portion of the stock in t e interval between said reduction devices, said prime mover being constructed to vary its speed independently of variations of length of that portion of the stock in the interval between said devices incident to the aforesaid tension changes.

4. The combination with metal reduction devices arranged in tandem for simultaneous action on successive ortions of a length of stock fed from one of said devices to the other, of prime movers for driving the respectlve devices individually, one of said devices being so driven as to pull the stock through the other to a certain extent, whereby the tension in the material between the two devices acts to transfer work from one of the prime movers to that of the other device, the prime mover of such following device being constructed and arranged to decrease in speed with an increase of load independently of changes in the length of the stock incident to an increase of load, substantially as described.

5. The combination of rolling mills arran in tandem, means to drive one of said mil s at a substantially constant speed, and an electric motor for driving the other mill, having a compound Winding, whereby said motor varies in speed with a variation of load to compensate for speed variations of the first mill; substantially as described.

6. The combination of rolling mills arran ed in tandem, of means to drive one of sairf mills at a substantially constant speed, and an electric motor for driving the other mill, having a relatively large shunt field winding, and a relatively small series field winding, whereby the speed of such last mentioned mill is automatically varied to compensate for speed chan s of the first mill; substantially as descri ed.

7 The combination of metal working devices arranged in tandem for simultaneous operation on a length of stock which passes from one of said devices to the other, means for driving the second device at practically a constant speed, and a motor for driving the first device whichvaries in speed with a variation of loadand is directly controlled by the variable tension on the stock, independently of chan es in the length of the stock incident to t e tension changes; substantially as described.

8. The combination of metal working def. vices arranged in tandem for simultaneous operation on a length of stock fed from one of said devices to the other, means for driving the second device at a practically constant speed, and an electric motor for driving the first device, having a series field winding whereby it is adapted to decrease in speed with an increase of load; substantially as described.

9. Apparatus for operating on material of the kind described, comprising a plurality of elements havin passes to simultaneously act on several di erent parts of the same piece of material, and means to feed the material through the passes, comprising an electric motor for each pass, at least one of said motors being so Wound as to decrease in speed with an increase of load whereby electric motor, said motor so wound the tension of the material being operated on directly and automatically controls the speed of the motors.

10. The combination of metal reducing devices arranged in tandem for simultaneous action on successive portions of a length of stock fed by one of said devices to the other, and separate prime movers for driving the respective devices independently, at least one of said prime movers constituted by an electric motor which is wound to vary its speed directly and automatically as a result of variations in the tension ofthe stock in the interval between said reducing devices, whereby said electric motor varies the speed of its reducing device to correspond with speed variations of the other reducing device; substantially as described.

11. The combination of metal working devices arranged in tandem for simultaneous operation on a length of stock fed by one of said devices to the other, a prime mover for driving one of said devices, an electric motor for driving the other device, and adjustable means for controlling the speed of said as -to decrease in speed with an increase of ldad on its reducing device without actuation of said speed controlling means, whereby the speeds of the reducing devices are directly and automatically controlled by variation of the tension of the stock; substantially as described.

12. The combination of metal reducing devices arranged in tandem for simultaneous action on successive portions of a length of stock fed by one of such devices to the other, and electric motors for driving the respective devices individually, so wound as to maintain automatically a predetermined speed ratio between said devices by the tension in the stock; substantially as described.

13. The combination of metal reducing devices arranged in tandem for simultaneous action on a length of stock, electric motors for driving the respective devices individually, so wound as to maintain automatically a predetermined speed ratio between said devices, and manually adjustable resistance means for controlling the speed of said motors; substantially as described.

14. The combination of metal reducing devices arranged in tandem for simultaneous action on a length of stock, prime movers for the respective devices, one of said prime movers being adapted to drive its reducing device at such speed as to pull the stock through the other device and thereby tension the stock to a certain extent, the prime mover of such other device being constituted by an electric motor having a compound winding whereby it is adapted to decrease its speed automatically with an increase of load due to a decrease of such tension of the stock, and variable resistance means for varying the speed of said compound wound motor; substantially as described.

15. The combination of metal reducing devices arranged in tandem for simultaneone action on successive portions of a length of stock, said devices having rotary parts adapted to feed the metal forward during the reduction thereof, separate prime movers for driving said rotary arts of the respective devices, and means For operativel connecting each prime mover with its re ucing device, at least one of said prime movers be ing geared directly to its reducing device and said prime mover being so constructed and arranged as to vary the speed of said remover for driving the other device, gear ng connectin one of the devices with its rime said other device from its prime mover, and 40 moverso t the formerls positivel driven, manually operable means for directly con;

' said prime mover being construe and artrolling the speed of said prime movers, said ranged to vary its speed directly and autolast-named prime mover bei constructed a matically bye variation in load transmltted and a to vary its spec? by said gearing to said prime mover when automatically'byvariations of tension in the 48 the stock undergoes a change of tension, instock transmitted to it through said transdependentl of a change of length in the mission mechanism, and inde dentl of length of e stock inci ent to such tension said m nually Repe -able ntra log change, and se arate manuall operable means and of changes in length of the etoo means for y controlling t eepeed of incident to ension cha such prime movers independently of the ten 19. The combination of metal reducing sion m the stock. devices arranged in tandem for simultaneous 17. The combination of metal reducing deaction on a length of stock a prime mover vices arranged in tandem for simultaneous for driving one of said evices, aprime operation on a length of stock fed by one of mover for the other device consist' of an said devices to the other, a prime mover forelectric motor, gearing for positively living-one of said devices, a prime mover such other device from said electric motor, for driving the Other device, gearing 0011- and adjustable means for directly controlnecting one of the devices 'with its prime ling the speed ofsaid primemovergsaidelecmoverso that the former is positivel driven, tric motorheing constructed and a said prime mover beingdcianstru and arto-decreasle its spear: witllll andincrease 0; load ranged to-vary its ee ireetly an autoimposedtt emon t oug sai rlng' yva s2 transmitted riation oftension'in the stock i nfidependently by said gearing to said prime mover when of said adjustable eed controlling means the Stock undergoes a change of tension, inand ot variations'of engths incident to tendependently of a change oflength 1n the S1011 changeswhereby the speed ofoneofeaid ion of Stock. incident to such devices is automatically changed to com ena J m en lltllly operable sate for speed changes of the other, sai ad- 6 P d' f justablecontrolling means and said autosue time moversindependently of the ten matic control being adapted for eimultane- 7.

" devices rranged in tandem for the. Sim?!- mon 1n the stock while the automatic oonous operation. a

' V In witness whereof, I have hereunto let tion of metal a we my (handpn the 20th y of August, 1912.

taneousoperationonalengthof a 1 j pnm mover for driving one oft-raid devices, Witnr arune mover for the other devi trans- E. .n u s sion m for positively driving M. 0m: 1 7mm.