US1767810A - Feeding mechanism for tube mills - Google Patents

Description

June 24, 1930. ,A. G. PLACE 1,767,810

MECHANISM. FOR TUBE MILLS Filed Sept. 24, 1927 2 Sheets-Sheet l nvvezvrae June '24, 1930. A. 6. PLACE 1,767,810

FEEfiiNe MECHANISM FOR TUBE nns Filed Sept. 24, 1927 2 Sheets-Sheet 2 INVENTOR #7 w/ T/vEss er a nrramvzrs fll/z'ed G. Blade;

Patented June 24, 1930 error ALFRED G. PLACE, OF YOUNGSTOWN, @I'TIO; EDNA L PLACE AND THE DGLLAR SAVINGS AND TRUST COMPANY EXECUTOES G1? SAID ALFRED G. ?LACE, DECEASED FEEDING E'IEOHANISI?! F03 TUBE IVIILLS Application filed September 24, 1927.,Seria1 1%. 221,710.

There has recently been developed a process for the manufacture of tubes and pipes from a pierced ingot which comprises essentially the rapid intermittent forging of the leading end of the ingot while the latter is supported on a mandrel between a pair of peculiarly grooved rolls rotating in opposite directions and in a direction opposed to the forward movement of the ingot, with the result that each time the ingot is presented to that-portion of the rolls grooved to formva pass of predetermined diameter corresponding to the exterior diameter of. the tube it is des red to produce, the ingot is .reducedin size and brought to the desired exterior diameter so that the tube is progressively formed and gradually projected from the rear side of the rolls until the whole of the metal in the ingot has passed between them. This process is commercially'k'nown as the Pilger process and the tube mill designed for operation in accordance with the process as a Pilger mill.

More specifically, the process contemplates the formation of a cylindrical ingot I of somewhat greater diameter than the tube whichis to be produced, the axial piercing of the ingot by any suitable means to a diameter approximating that of the internal diameter of the tube and the delivery of the ingot so pierced and .while heated, to a proper position inthe mill, and in front of the rolls thereof. Upon the attainment of this position by the ingot, a mandrel-whose diameter approximates the interior diameter of the tube is then moved longitudinally into the bore or hole in the ingot and the mandrel and ingot then moved forward, preferably as rapidly as possible, until the leading end of the ingot approaches the rolls which latter are rotating in opposite directions and in opposition to the forward movement of the ingot. The rate of longitudinal travel of the ingot is now materially reduced say, under ordinary conditions, to approximately 80 a minute and the leading end of the ingotentered between the rolls while the latter are in such relative position that their respective grooves form an opening I, sufi i ciently great for this purpose. As the rolls now continue their rotation those portions of their respective grooves which are formed to the semi-circumference of the exterior of the tube to be formed are brought together upon the end of the ingot with the result that while the ingot as a whole, together with the mandrel, is forced rearwardly, a certain portion of the leading end of the ingot is elongated and reduced in diameter correspond with the pass between-the rollsto thereby form the leading end of the tube. So long as the continued rotation of the rolls maintains the said portions of the roll grooves in juxtaposition, the rearward thrust on the ingot is continued, but the moment that the larger portions of the roll grooves approacheach other and thus free the ingot, the mandrel and ingot by suitable means hereinafter-described are once more projected forward having meanwhile been given a predetermined axial movement of rotation, so that as the narrower portions of the roll grooves again come into prox imity through the rotation of the rolls the latter will again act on the ingot; thus as the ingot throughout the rolling operation is being continuously but slowly moved toward the rolls as above described, a fresh increment of the ingot is presented to the rolls on each forward movement of the ingot with resultant ensuing formation through the action of the rolls of a short section of the tube which latter, as it .is thus progressively formed, gradually extends farther-and farther from the rear side of the rolls until all of the metal intheingot has'passed between j the tube than is required for any of the other movements of the carriage including the subsequent rearward movement thereof required to entirely clear the mandrel from the tube and bring the carriage back to its initial position at the rear of the ways, thereby, completing the cycle and placing the mill in condition forthe reception of another ingot. Moreover, this short movement at the initiation of the stripping operation requisite for starting the mandrel from the tube must necessarily be performed at relatively slow speed and requires the expenditure of a great amount of power although after the mandrel is once loosened but a relatively small amount of power is thereafter required to complete its withdrawal from the tube. Thus, as in the case when the carriage is moved forward before the rolling operation so as to bring the ingot up to the rolls, it is desirable with a view to economy of time and consequent increase in the productive capacity of the mill to move the carriage rearwardly after the man drel has started from the tube as rapidly as possible so as to bring it to its initial position in a minimum time.

It is thus apparent that in the carrying out of the process the initial movement of the carriage from the rear of the ways toward the rolls may be made at a relatively high speed; that the subsequent forward speed of the carriage during the rolling operation must be made at a relatively slow speed but accurately, smoothly and continuously,'that following completion of the tube a maximum amount of powermust be applied to the carriage at the initiation of the stripping operation to move the carriage slowly rearwardly for a fewrinches onlyto start the mandrel from the tube and that thereafter the carriage may be caused to complete its rearward movement to initial position relatively rapidly.

As hitherto stated, it has been customary to effect these. various movements of the. carriage by hydraulicallyoperated means including pistons suitably connected to the carriage and disposed in cylinders extending parallel to the ways in association with means for admitting water under pressure selectively to the opposite ends thereof so as to effect the desired movements of the pistons and in turn of the carriage'said means being under the manual control of the operator'of the mill. Under practical conditions of operation, however, this-method of controlling the movements of the carriage is not entirely satisfactory as it is almost impos- R. sible to prevent variations in the pressure of the water supply, pulsations and the like in consequence of which a predeterminedopening of the controlvalves' does not always result in the desired or expected. movement of the carriage while, additionally,"fiuctuations frequently occur in its rate of movement. Thisinability to control the speed and movements ofthe carriage with the requisite nicety is particularly disadvantageous during the rolling operation for during that portion of the cycle it is substantially imperative that the forward movement of the carriage be continuous, smooth and at a given rate for if this predetermined rate of travel is exceeded, too much of the ingot will be presented to the rolls at each revolution thereof resulting in breakage of the rolls or other parts or stoppage of the mill, while on the other hand, if the predetermined rate is not maintained, difficulty may result from the cooling of the ingot below the proper temperature before the completion of the tube while, in any case, the speed of production is'diminished below that of which the mill is capable. Moreover, the use of high pressure water for performing given mechanical operations of the general character to which'reference has been made and which are necessarily incident to the use of the Pilger process for producing tubes is always more or less unsatisfactory and a source of annoyance and expense by reason ofbreakage of pipes and flexible tubing, leakage, difficulties arising in the operation of the pumps and necessity for constant maintenance of an adequatesource of water supply.

It is therefore a principal object of the present invention to provide means for effecting the movement or feed of the carriage in a Pilge'r mill which are not open to the aforesaid objections inherent in the hydraulically actuated mechanism heretofore employed, and more particularly to provide electrically actuated means for this purpose so constructed and arranged that the requisite movements of the carriage may be effected with the nicety, power and speed requisite for satisfactory operation and maximum output of the mill.

Further objects, and novel features and advantages comprehended by my invention will appear more fully hereinafter.

To enable those skilled in the art to readily comprehend and practice my invention I have illustrated in the accompanying drawings and will now proceed to describe certain forms thereof, it being ofcourse understood that by so doing it is not my intention to confine or limit myself to any ment of the various elements as the same are susceptible of material variation from' the precise embodiments illustrated and to which reference will hereinafter be made without departing from the spirit and scope of the invention considered in its broader aspects. 7 i

In the accompanying drawings Fig. 1 is a somewhat diagrammatic top plan view of a Pilger tube mill embodying one-form of on a somewhat enlarged scale.

my invention, Fig. 2 is a side elevation thereof and Fig. 3 is a rear end' elevation In both Figs. 1 and 2, it has been necessary, owing to the relatively great size of a mill of this character to break through the figures at several points to enable the same to be placed on the sheet. Fig. 4- is a fragmentary enlarged View, partially in transverse vertical section, indicating in a somewhat diagrammatic way the relative position of the rolls and ingot when a portion of the latter is entering the pass of the rolls and Fig. 5 is atransverse section, partially in elevation, on-line'55 in Fig. 4, while Fig. (dis a fragmentary top plan view showing a form of the invention slightly modified "lower. rolls'2, 3 arranged to be driven in anysuitable manner through the medium of their respective roll shafts 5 in the direction indicated by the arrows in Fig. a. In

front of the rolls and extending rearwardly therefrom are disposed parallel laterally spaced ways 6, 7 on which is slidably disposed a carriage generally designated as 8 and which may comprise front and rear. transverse yokes- 9, 10 connected by longitudinally extending rods 11. The front yoke 9 forms an integral part of the air cylinder 12 through which extends apiston rod'13 on which within the "cylinder is disposed a piston (not shown), the rearwardly' projecting end of the rod being surrounded by. a guide casing 14.- This cylinder may be connectediby suitable flexible piping (not shown) with an air reservoir 15 conveniently disposed between the rear ends of the ways and may also serve to. support a forwardly extending guide 16 inwhich is slidably disposed a coupling: head 17 -mounted on the forward end of the piston rod. To this head is removably secured the rear end of the mandrel 18 through the medium of any suitable coupling devicegen erally designated as 19 w-hileslidably seated on j the mandrel is a grooved collar 20 adapted for engagement by the vertically movable dog or. stop 21 duringthe. strippingoperation. r r

Theseseveral parts are common to mills of this 1 general character and. requireno further description. Extending rearwardly from the carriage 8 and conveniently secured. at the forward end to the yoke 10 thereof is a long exteriorly threaded rod 25; this rod extends through c and is cooperative with a nut or interiorly threaded bore formed in the hub 26 of a gear wheel 26 surrounding therod'and forming part of a geartrain having any suitable number of gears toeffect the requisite speed reduction hereinafter referred to. This train of gears which, as shown, comprises the gear 26, an idler gear 27 and a drive pinion 28, is disposed in a suitable housing generallydesignated as 30 arranged transversely of the ways and at a point in the rear thereof so as to be entirely clear of the carriage when the latter is in its retractedor rearmost position the housing, of; course, being provided with suitable journals in which the gear shafts are supported. The particular method of mounting and'journaling the gears is a matter. of choice so long as the parts are arranged in sucha way that when the outermost gear constituting the. drive pinion of the train, for example,thepinion 28, is driven in a given direction theinner gear 26 will be rotated, conveniently in the same direction, and thus, asthe inner gear is restrained from endwise movement by the housing serve to impart to the rod and'hence to the carriage a longitudinal movement of progression the direction of which is determined by the direction of rotation of the pinion.

Preferably the outer extremity: of V the rod may be supported onsuitably-mounted rollers 32 so as to preserve its proper of the train is elfected'from a motor 35 which is coupled by a coupling 36 tothe shaft 37 on. whichthe pinion is mounted, the motor alignment, the rod ofcourse extendingv en- 7 being conveniently positioned adjacent and i in rear of the geartrain housing. This ;1no-;

tor in accordance with my invention is'a direct currentmotor receiving its power supply from a separate motor=generator set comprising a motor 38 and generator 39 coupled thereto, the several units being so constructed and wound that the direction-of rotation of'the motor 35 oanbe controlled by reversing the field of the generator while the speed of'op'eration andpower delivered 1 by the motor 35 may be controlled by varying'the amount of voltage applied to the generator field. For attaining these several results the motor 35 and generator 39' may requisite wiring between the various units,

control panel and the switch as the details thereof form no part of the present invention and are. well understood by those. familiar with this method of controlling the operation of a direct current motor from a motorgenerator set and which is commercially known as the W'ardLeonard principle or system of control. Current may be supplied to motor 38 from any suitable source by wires W, while other wires WV may be arranged to supply current to motor 35 for the purpose of exciting its field.

It will thus be apparent that with the various parts arranged substantially as described it is possible by suitable operation of the master switch S to vary the voltage gen erated by generator 39' and impressed on the armature of motor 35, and also toovary a resistance in series with the field of motor 35 so as to vary the speed thereof and, in turn, the rate at which the gear 26 is turned to thereby move the carriage along the ways in a given direction at a predetermined and constant speed; additionally, by reversal of the field of the generator-3,9 the direction of rotation of the motor 85 may be reversed so as to move the carriage in the opposite direction. Thus, the operator is able to effect a a movement of the carriage along the ways in either forward or reverse direction at relatively high speed as, for example, from 60 to 80 feet a minute by impressing a high voltage upon the motor 73.5 and is thus enabled to movethe carriage from its initial position to carry the ingot Iup to the rolls at the commencement of the cycle very rapidly and with a relatively small expenditure of power. Thereafter during the rolling operation the requisite slow forward feed of the carriage approximating, as hitherto stated, some 30 inches a minute, may be readilyattained by decreasing the voltage impressed on the motor to a predetermined minimum, and as this voltage is substantially constant and not subject to material variations, the rate of carriage feed during the rolling operation is substantially continuous whereby during each complete revolution of the rolls the carriage, and in turn the ingot, will be moved forward for a predetermined distance so that the same bite will be taken by the rolls on the ingot each time the latter is presented to them.

After the completion of the" tube T, by reversing the generator field the requisite reverse movement of the carriage may be as readily effected, at first slowly by theuse of a low voltage until the grooved collar 20 is aligned with the dog 21 so the latter can be raised to engage the collar then by applying a full field. to the motor 36 the latter may be caused to exert through the gear train a maximum motor torque and consequent max imum rearward pull on the carriage so as to start the mandrel from the' pipe, an operation which requires a'carriage'movement of some 4" which of course is effected quite slowly owing to thestrong adherence of the mandrel to the tube.- Assoon, however, as

the mandrel is loosened in the tube, the speed of the carriage can be rapidly in creased and may thereafter by suitable control of the voltage impressed on the motor,- be maintained at any desired rate so as to move the carriage rapidly rearwardly to inltial position, desirably, at substantiallythe same rate at which it was moved forward at.

vided may be disposed either on its upperor its lower surface; forconvenience of illuss tration they are shown on the former in the said figure. A pinion 41 disposed on a shaft 42 journaled in suitable housings 43 is arranged for cooperation with the rack and the shaft connected, as by acoupling 44, with a gear shaft 45 journaled in a gear train housing 46 disposed adjacent the ways which, however, are not shown in said figure;

Upon the shaft 45 may be mounted a gear 47 which forms part of a reduction gear tram comprising a sultable number of gears.

and a drive pinion, for example and as shown, the gear 47', a pinion 48 meshing therewith and disposed on a shaft 49 also carrying a gear 50 engaging the drive pin ion 51 on a drive shaft 52 which'is coupled, through the medium ofa coupling 53, with a motor 35, the ratio of the gears forming the train being of course calculated to effect the desired speed of reduction between the pinion 41 and the motor. The motor-generator set comprising the motor 38 and gen erator 39 together with the control panel 1?,

master switch S and wiring connections may be the same in this formof the invention as that previously described with resulting similarity of operation.

It will thus be apparent that by the use" of my invention the slow, continuous and non-fluctuating forward feed of the carriage and ingot requisite during the rolling opera-.

tion for theproduction of the tube with maximum rapidity yet without danger of stopping the mill or damaging the parts thereof may be readily attained; that, with equal facility, a maximum amount of power may be applied-to the carriage momentarily to move the latter rearwardly at the commencement of the stripping operation and that whenever desired at other times during the tube-forming cycle, the carriage may be moved rapidly, smoothly and accurately along the ways in either direction with re-' sulting increase in the productive capacity of the mill in a given period.

Moreover, by the use of my invention the difficulties inherent in and annoyances arising from the use of hydraulic means for moving the carriage as heretofore employed in tube mills of the Pilger type are entirely avoided, a mill constructed in accordance with my invention being less liable to get out of order and less subject to shut-downs therefrom than those in which the carriage feed is efiected by such means. While therefore the primary object of my invention, as stated, is to enable the carriage to be fed with the requisite nicety and at the maximum speed which can be utilized during the actual rolling portion of the cycle, to at other times enable the carriage to be moved very rapidly along the ways, and to provide means for applying a maximum rearward pull on the carriage when required during the stripping operation, these other advantagesarising from the use of my invention to which I have ust referred also materially contribute to the practical value of the invention by furthering the productive capacity of the mill and minimizing operating expense over a given period.

Having thus disclosed my invention, I claim and desire to protect by Letters Patent of the United States:

1. In a machine for forming tubes from a pierced ingot by progressively moving the ingot through a pair of grooved rolls rotat ing in opposition to the movement of the ingot, a pair of rolls, ways disposed in front of the rolls, a carriage adapted for reciprocation on the ways and means for reciprocating the carriage for feeding the ingot forwardly to the rolls at different speeds and for moving the carriage backwardlygat different speeds to produce a slow starting movement and then a rapidbackward movement, comprising a motor, means interconnecting the carriage and the motor whereby rotation of the motor in a predetermined direction is operative to impart movement to the carriage in a corresponding predetermined direction, a generator, means for driving the generator,- connections between the generator and the motor, and control means operative to vary the output voltage delivered to the motor' from the generator whereby said carriage may be moved on the ways at predetermined speeds under different loads by suitably varying said voltage.

'2. In a machine for forming tubes from a pierced ingot by progressively moving the ingot througha pair of grooved rolls rotating in oppositionto the movement of the ingot, a pair of rolls, ways disposed in front of the rolls, a carriage adapted for reciprocation on the ways and means for reciprocating the carriage for feeding the ingot forwardly to the rolls at different speeds and for moving the carriage backwardly at different speeds to produce a slow starting movement and then a rapid backward movement, comprising a motor, means interconnecting the carriage and the motor whereby rotation of the motor in a predetermined direction is operative to impart movement ina correspondingly predetermined direction to the carriage, a generator, means for driving the generator, connections between the generator and the motor and control means operative to vary the output of the generator and polarity and strength of its field whereby said motor may be caused to rotate. at varying speeds in either direction so as to correspondingly move the carriageon the ways. V

3. In a tube mill of the Pilger'type, the combination of a pair of grooved rolls, ways extending from the forward side of the rolls, a carriage slidable on the ways and means for reciprocating the carriage for feeding an ingot forwardly to the rolls at different speeds and for moving the carriage back.- wardly with a slow starting speed and then a rapid backward movement comprisinga motor, means connecting the motor and the. carriage whereby rotation of the motor in. a predetermined direction will cause movement of the carriage on the ways in a corresponding predetermined direction, a motorgenerator set, means for supplying current to the motor thereof, connections between the generator and the first mentioned motor, and control means operableto vary the output of the generator and to effect a reversal of the polarity of its field whereby said first. mentioned motor may be caused to rotate at different speeds and in either direction so as to move the carriage on the ways in either direction andat different speeds at different points in its path of travel.

4. In a tube mill of the. Pilger type, the combination of a pair of grooved rolls, ways extending from the forward'side of the rolls, a carriage slidable-on theways and means for reciprocating the carriage for feeding an ingot forwardly to the rolls at different speeds and for moving the carriage back wardly with a slow starting speed and then a rapid backward movement comprising a motor, a reduction gear'train having one end connected with the motor and the other end co-operative with means extending rearwardly from the carriage for moving the carriage in correspondence with the direction of rotation and speed of the motor, a motor-generating set, means for supplying current to the motor thereof, connections be-. tween the generator and the first mentioned motor, and control means operative to vary the out-put of-the generator and to effect a. reversal of the polarity of itsfield to thereby control the direction of rotation and speed of the first mentioned motor.

I 5. In a tube mill of the Pilger type, the combination of a pair of grooved rolls, ways extending from the forward side of the rolls,

a carriage slidable on the ways and means for reciprocating the carriage for feeding an ingot forwardly to the rolls at diiierent speeds and for moving the carriage backwardly with a slow starting speed and then a rapid backward movement comprising a motor, a threaded rod extending readwardly from the carriage, a reduction gear train co-opeartive at one end with said rod and at the other end with said motor whereby rotation of the motor at a predetermined speed in a predetermined direction is operative to cause movement of the carriage through said gear train and threaded rod in a correspondingly predetermined direction and at predetermined speed, a generator, means for driving the generator, connections between the generator and the motor, and control means operable to vary the output of the generator and the polarity of its field to correspondingly vary the speed, power output and direction of rotation oi the first mentioned motor the power supplied to the threaded rod through the gear train adapted to be graduated in correspondence with the resistance to movement ofiered by the can riage, so that the carriage may be moved in either direction under diflerent loads at predetermined speeds along theways.

In witness whereof, I have hereunto set my hand this 15th day of September, 1927.

ALFRED G. PLACE.

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