US2387515A

US2387515A - Reducing mill

Info

Publication number: US2387515A
Application number: US442769A
Authority: US
Inventors: Heber C Inslee
Original assignee: ROCKRITE PROCESSES Inc
Current assignee: ROCKRITE PROCESSES Inc
Priority date: 1942-05-13
Filing date: 1942-05-13
Publication date: 1945-10-23
Anticipated expiration: 1962-10-23

Description

kt- 3. 9 H.: .1NS'LEE' 2.381515 REDUCING MILL Filed May 15, 19421 1o Sheets-Sheet 1 Oct 3, I945' H. c. INSLEE 2,387,515

REDUCING MILL Filed

Ma

13, 1942 10 SheetsaSheat 2 MATToNEY Oct. 23, 1945.

' 1o snags-sheet 3 Filed May 15; 1942 i E INVENTOR BY 6 I M ATTORNEY o o Q 0 N3 an 0 mm. 0 W 5% H. c. INSLEE amnucme 'MILL Filed May 15, 1942 lo sheets -shegat 4 H. C. INSLEE REDUCING MILL Filed-May 13, 1942 10 Sheets-Sheet e INVENTOR I ATTORNEY 1Q Sheets-Sheet 7 Oct. 23, 1945. H. c. lNSLEE REDUCING MILL Filed Ma 15, 1942 I ATTORNEY g! Fyz TOR BY Oct. 23, 1945. Q [NSLEE 7 2,387,515

' REDUCING Mm,

Filed May 15, 1942 10 Sheets- Sheet a "'iiiiiii' n nu i-? vET'oR ATTORNEY Oct. 23, 1945. H. c. 'msLEE r 253 REDUCING mm. Filed May 13. 1942 10 Shams-sheet 9 I ATTORNEY Patented Oct. 23, 1945 s" PAT NT; orries REDUCING MILL I Heber 0. Inslee, East Orange, N. J., assignor, by mesne assignments, to Rockrite Processes, Inc., 7 Stamford, Conn.,'a corporation 01' Delaware Application May 13, 1942, Serial No. 442,169 p .00 Claims. (01. ac-14) This invention relates to apparatus for reducing metal tubes and bars. ,The invention has been made especially with the idea of providing an improved apparatus for reducing metal tubes in thecold state, but features of the invention may be used also for hot reduction of tubes, and ieatures of the-invention are adapted-for the hot or cold reduction oi' bars or rods.

More particularly, the invention relates to ,a step-by-step reducing mill oi the Pilger type, that is, one in which the workpiece, or stock, reciprocates between gapped die rolls which rotate continuously in one direction about fixed axes, the die rolls reducing the workpiece during its successive strokes in, one direction and leaving it tree during its non-working return strokes, and the workpiece being given anincre-v ment of feed-and a partial turn for each com-' plete reciprocation; and to a reducing mill this type in whichthe movement of the workpiece,

and also of the mandrel in a tube-reducing mill,

ing cost compared to its output, and to provide mechanism whereby the working stroke of the workpiece and mandrel is lengthened to extend over a time during which the die rolls make substantially more than half a rotation and the major portion of the working stroke during which the workpiece and mandrel are driven at approximately the pitch line speed of the die rooves is lengthened and the die portions, or work-engaging portions, of the rolls are correspondingly lengthened.' Because of this the amount of work which can be performed on the workpiece-during each working stroke is increased orthe compressive force required for performing a given amount of work is reduced, while because of the quicker movement of the reciprocatingparts during'the non-working return stroke there is 'no loss in the possible speed ing stroke does not result in an excessively short time for acceleration and deceleration oi! the reciprocating parts atthe' beginning and end of the working stroke, there being more time left for such acceleration and deceleration than there such a mill which shall produce tubes or bars of high quality with regard both to form and finish, and which shall be convenient to operate, durable, and of low maintenance cost. 7

The high eiliciency and high capacity of mills according tothe invention are due in large part to the facts that excessive weight of the reciprocating parts of the mill is avoided, and that the reciprocation oi the work-piece and mandrel is effected by means of a driving mechanism whereby a nearly constant linear velocity approximately equal to the pitch line speed of the die grooves of the die rolls is given to the workpiece and mandrel during a major portion of the stantially the pitch line speed oi. the die grooves being accomplished inthe part of the working stroke preceding such major portion and decel-I would be it the working stroke were limited to rolls rotate only the time during which the die 180.

The emciency and capacity of Pilger mills and other metal reducing mills depends primarily on the operating speed of which they are capable without impairment or smooth operation. In

mills oi the ordinary Pilger type, where the rolls grip the workpiece while the latter is stationary,

a considerable shock is produced by each impact e'rationinthe part following such maioiporti0n."

of the dies on the metal workpiece. These continuous shocks could not be tolerated. in cold working without injury to the workpiece andthe rapid impairment of the dies. Consequently, for reducing cold workpieces such a mill would have to run very slowly, too slowly, in fact, to be really practicable'ior cold working at. all. An

important result of the driving mechanism of thepresent' invention is that at the beginning of the working stroke the workpiece is started in mo tion and its speed brought up to approximately the pitch line speed of, the die grooves before the workpiece is engaged by the dies, working parts, all of which will be clearly brought out in the following description of a tube-reducing mill embodying the various features of the invention in the form now considered best, and thereafter specifically pointed out in the claims.

In the accompanying drawings:

Fig. 1 is a plan view of a tube-reducing mill embodying the various features of the invention in the form now considered best;

I Fig. 2 is a side view of the mill;

Fig. 2a is an enlarged detail view showing one pair of the die rolls in section and the mandrel between them, at the end of the forward nonworking stroke;

Fig. 3 is an enlarged plan view of the mandrelreciprocating mechanism and adjacent parts with the mandrel unit housing sectioned;

- Fig. 4 is a side view of parts shown in Fig. 3;

Fig. 5 is a section taken on line 5-5 of Fig. 4; Figs. 6, 7 and 8 are detail sectional views taken.

respectively, "on lines 6--6, I-'| and 8-8 of Fig. 4;

Fig. 9 is l an enlarged view of. the tube feed mechanism taken on line 9-9 of Fig. 1;

Fig. 10 is a broken view of parts of the tube feed mechanism taken on line Ill-l0 of Fig. 1,

.Fig. 10 being on the scale of Figs. 3, 4 and 5, and

Fig. 9 being on a slightly larger scale;

Fig. 11 is an enlarged side view of the tubereciprocating mechanism shown in Fig. 2;

Fig-12 is a section the righthand portionof which is taken on line I2a.l2a of Fig. 11 and the left hand portion on line l2b--l2b of Fig. 11; -Figs. 13. 14 and 15 are sections taken on line 16 is an enlarged side viewof the tube reciprocating and turning mechanism'at the exit side of the roll stand;

- Fig. 1'7 isan end view partly broken away of the mechanism shown in Fig. 19;

Fig. 18 is a section taken on line i8--i8 of Fig. 16;

Fig. 19 is an enlarged plan view, and Fig. 20 a corresponding side view, of the drag link quickreturn mechanism, shown at the right hand end of Fig. 1, through which the tube and mandrel are reciprocated; and V V 21 is a diagram illustrating the quick return motion imparted to the tubes and mandrels. The tube reducing mill illustrated is a duplex gapped working rolls and means for reciprocatlustrated, and most desirably, the reducing action takes place during the backward stroke of the tubes and mandrels, the non-working return stroke being in the forward direction, that is, in the direction toward the reduced end of the tube.

. It will be obvious that many of the features of the invention may be embodied in mills havin only one pair of die rolls and meansfor reciprocating only one mandrel and tube, or in mills difiering otherwise from the mill illustrated.

The complete mill illustrated comprises a roll stand 30, a mandrel reciprocating and turning unit 3|, a tube reciprocating, turning and feeding unit 32, a tube feeding mechanism 33, a quickreturn driving mechanism 34, and an exit tube reciprocating and turning unit 35. The roll stand comprises a massive frame or housing 40 in which are mounted two pairs of overhung die rolls 4| and 42 fast on opposite ends of two die'rolls a prel'oad aproximately equal to the 4 rolling 1oad on the die rolls. 'This roll stand forms the subject matter of my copending application Serial No. 442,768, filed May 13, 1942, now Patent No. 2,358,929, issued September 26,

. 1944, and for further description thereof refermill, having two pairs of continuously driven ing a mandrel and tube betweenthe rolls of each pair, and means whereby the tubes and man- 'drels are given a partial turn and the tubes are given an increment of feed between successive working strokes, the working rolls having, in the usual manner, tapered die grooves which act on the tubes during the working stroke of the tubes ence is made to said application. At the entrance side of the housing 40 there are two tube clamping devices, of which one is shown in Fig. 2, one for each pair of die rolls 4| and 42, each comprising a lower stationary'member 41 and an upper vertically movable clamping member 48. The clamping members 48 are in aised position during the operation of the mill, and are moved down to clamp the partially reduced tubes against the members 4'! by air cylinders 49, of which one is shown in Fig. 2, when the mill is stopped. I

Ma'ndrel reciprocating and turning unit The operating parts of the mandrel reciprocating and turning unit 3| (see Figs. 1 to 8) are mounted in a stationary housing 50 seated on the rear end of a longitudinally extending base 5|. The operating parts are driven by a transverse driving shaft 52 which is oscillated by the quickreturn mechanism 34 to have a relatively slow movement in one direction and a quick return movement in the other direction. Mounted fast on the oscillating shaft 52 are two lever arms 53, one on each side of the spaced walls 54 of the housing. Each of these lever arms reciprocat'es one of the two mandrel bars 60. Each mandrel barhas at its forward end a tapered mandrel 6| (see Fig. 2a).

Each of the mandrel bars extends through and is removably secured to a longitudinally reciprocable and axially rotable holder'formed by a sleeve 62 which is slidably mounted in and keyed to an axially rotatable sleeve 63 mounted and held against endwise movement in apart of the housing 50. The forward end of sleeve 62 is rotatably connected by bearings 62a to a cross-head 64 which is mounted-to reciprocate on slideways 65 carried by the housing 50 and extending longiforward, or non-working stroke.

relative longitudinal movement some; the two.

Cross-head II is connected by links 99 to the forked end of one of the lever arms 93 so that as the arm 93 oscillates the mandrel-holding sleeve 92 and the mandrel bar are reciprocated, the mandrel bar making one complete reciprocation backward and forward for each rotation of the die rolls. For changing the length of stroke of 'the mandrelbar for operating with die rolls of different diameters, the points of pivotal connection of the links 99 to the arm 53 are adjustable for varying the effective radial length of the arm. As shown (Figs. 4 and 5), the connection of the links to the fork ends of the arm-may be made at any one of three pivot pin holes 91, and these pivot pin holes are formed in blocks 98 extending into the slotted fork ends of the arm from cap pieces 99 which are bolted to the arm fork I ends. By using different blockswith one or more differently positioned pivot pin holes, the throw of the mandrel bar may be adjusted not only for die rolls'of the threesizes provided for by the three pivot pin holes of the blocks 98 as shown,

, but for die rolls of other sizes within the, range Y permitted bythe length of the blocks 99.

Each mandrel bar is secured to its sleeve 92 by means of a mandrel clamp 19 at therear end of the sleeve. This clamp as shown has .gripplng Jaws II which are forced against the mandrel bar by a wedging collar 12 which is drawn against the inclined faces of the gripping jaws by the turning of a screw collet .13. The particular construction of this mandrel bar clamp is not of special moment.

In the use of the mill, the mandrel bar must be released from the holding sleeve 92 in order a part of the mandrel clamp when the mandrel bar has been moved forward to the right position longitudinally with relation to the. sleeve. such engagement being with the jaws .1I as shown. This stop 14 is most desirably formed as shown in Fig. 8 by a nut screwed on to the threaded end of the mandrel bar'and having a collar 14a for engaging the ends of jaws 1|. The stop is thus adjustable on the mandrel bar, providing for adjustment of the tapered mandrel with relation to the die rolls. A look nut 15 servesto lock the stop nut in'a'djusted position.

Two longitudinalrock shafts 89 extend forward one from each side or the mandrel unit housing 99, each being joumalled in bearings 92 and. mounted on

lateral extensions

94 and 95 of the base SI and held by their bearings against longitudinal movement. Each of these longitudinal shafts 99 is oscillated from the drive shaft 92 by a segment gear 99 on the drive shaft meshing with a bevel pinion 91 on the shaft".

of one of the arms 53. a i In addition to being reciprocated, themandrel bars are j given a partial rotation during each rotation of the mandrel bars is accomplished by turning the rotatably mounted sleeves 98 in which the sleeves 92 "to which the mandrel bars are secured are slidably' mounted and splined to 3 rotate therewith. For this purpose, the two sleeves 99 are geared together by means of. a" sprocket chain 99 connecting sprocket wheels 9i fast on the rearward ends of the sleeves, and one of the sleeves 69 has a sprocket wheel 92 fast thereon which is geared by sprocket chain 93 to a small sprocket wheel 94 driven by an overrunning, or one-way, clutch 95 carried at the end of an extension 99 of one of the oscillating shafts 99, this shaft extension 99 being supported near its end by a bearing 91. An idler sprocket carried by a spring tensioned arm 99 bears against the chain 93 to take up any slack in the chain.

An idler sprocket 99 serves the same purpose for the chain 99. The two mandrel bars will thus be given a partial rotation during each forward non-working stroke but will not be turned during the rearward, or working, strokes. The size ratio of the sprockets 92 and determines the number of degrees through which the mandrel bars are turned during each forward stroke, and this may be degrees or any other suitable number.

of degrees, and is adjustable by changing these sprockets.

Tube reciprocating, turning and feeding unit The tube reciprocating, turning and feeding unit 32 comprises a substantial housing I991 which a and mandrel bars.

Referring to Figs. 1, 2 and 11 to 15, each of these tube-reciprocating mechanisms comprises a longitudinally reciprocable and axially rotatable holder formed by a sleeve I 95 through which the mandrel bar extends and which isslidably mounted in and keyed to an axially rotatable Thispartial sleeve I 99 mounted and held against endwise movement in a part of the housing I99. At its forward and sleeve I carries a tube clamp I91 for gripping the rear end of the tube T. This tube clamp is similar'to the mandrel clamp 19, having gripping jaws I99 which are forced against the tube by a wedging collar I99 drawn against the inclined faces'of the gripping jaws by the turning of a screw collet H9. The rearward end of sleeve I95v is rotatably connected, as shown in Fig. 15, to a cross-head Il5 mounted to slideon longitudinally slideways H6 carried by the'housing I99, the bearings between the sleeve and cross-head being formed to lock them against relative longitudinal movement. The cross-head H5 is connected by links II1 tothe forked end of a lever arm I29 carried by a hub I2I rotatably mounted on oneend of a shaft I22, on the other end of which shaft the corresponding arm I29 of the tube reciprocating mechanism at the other side of the housing is mounted. Ex-

tending from the hub of each of the arms I29 is a bevel gear segment I25 which meshes with a bevel pinion I29 carried by a sleeve I21 slidable on one of. the shafts 99 and'splinedthereto so as to be turned thereby.' These pinion-cagryingv sleeves I21 are also held against longitiidinal movement with respect to the housing I99 and to ,move therewith by means of bearings I29 carried by brackets I29 on the housing. By the os-' clllation of shafts 89, therefore, the arms I29 are oscillated and through links II1 and crossheads II6 reciprocate sleeves I and the tubes secured thereto.

The arms I20 of the tube unit and the arms 63 of the mandrel unit have the same angular mo- 'tion and are of the same eifective radial length and are driven in unison, so that the tube and mandrel are given equal and synchronous reciprocations'. In order to reduce the torsional strain on the spline shafts 80, they are driven at a higher angular velocity than the drive shaft 52,

' the ratio of the pitch radius of gear segments 86 to that of the pinions 81 stepping up theangular.

velocity of the spline shafts in, for example, a 3

to 1 ratio. In order that the armsI20 of the non-working stroke as is given to the mandrels.

The sleeve I21 on one side of the mill carries a gear I30 which meshes with a gear I3I- from which, through an overrunning, or one-way, clutch I32, a pinion I33 on a shaft mounted in bearings I34 is driven, and pinion I33 meshes with a gear I35 on rotary sleeve I06. The sleeves I06 of the two tube-reciprocating mechanisms of thetube unit are connected by a sprocket chain I31 running on sprockets I38 fast on the two sleeves I06 and'held tight by an idler sprocket I39. The sleeves I06 and thereby the sleeves I05 and tubes secured thereto, are thus given a partial rotation during each forward, or non-working, stroke of the holding sleeves and tubes. The number of degrees through which the tubes are turned during each forward stroke depends on the ratio 01 pinion I33 and gear I35, and is adjustable by changing these gears.

Tube feeding mechanism During each non-working stroke of the sleeves I05, the tube unit housing I00 is given a short forward feeding movement efiectin'g an incretion. This worm I55 meshes with a worm gear I66, the worm gear being turned through a small angle by the worm during each non-working stroke, and the worm gear turns the rack pinion I40 through a shaft I51. The tube unit is thus I given a small forward feeding movement during each non-wcrkingstroke- The amount of such feeding movement may be varied by varying the 'point of connection of the links I49 to lever arm I48. This variation of the P int of connection of the links to the lever arm, that is, of the effective length ofthe lever arm, is effected as shown by means of an adjusting screw I60, by turning which a block I 6| to which the links are pivotally connected may be adjustably positioned lengthwise of the lever arm. The feeding movement will usually be from to and as this feed is spread over the return stroke of, for example, about 23", the feed motion is notably free from shock.

Connected to the worm shaft I54, is a small electric motor I65 by which the rack pinion I40 is driven through worm I55 and worm gear I56 and shaft I51 for causing the quick return movement of the tube unit or for adjustment of its position by movement in either direction. During the step-by-step feeding of the tube unit the motor overhauls, and before the motor is operated the clutch I53 isdisengaged. The motor is under push button or other suitable control for either forward or reverse operation. The clutch is engaged and disengaged by means of a hand lever I66 (Figs. 2, 4 and 9) ona clutch-operating shaft I61, and, in order to prevent operation of the mill when the tube unit housing I00 is being moved by motor I65, a switch I68 is operated by the hand lever I66 to open the mill motor circuit when the clutch is disengaged.

Earit tube reciprocating and turning unit As the reduced portions of the tubes advance beyond the die rolls they are engaged by fricment of feed of the tubes with relation to the mandrels. This step-by-step forward feeding of the tube unit is effected'by a pinion I40 driven through a one-way clutch from one of the-oscillating spline shafts 60, the pinion meshing with a rack I4I extending backward from the tube unit housing through a guide opening in the stationary housing of the mandrel unit. This pinion and rack serve also for giving aquick return movement to the tube unit when, after being I are effected, is shown in Figs. 1, 2, 3, 9 and 10.

tipn clamps I10 of the exit tube reciprocating and turning unit 35 (see Figs. 16, 17 and 18).

This unit comprises a stationary housing I1I rotatable sleeve I12 which is slidably mounted in and keyed to an axially rotatable sleeve I13 disconnected from the nearly completed tubes, it is to be moved back for the positioning of new ,tubes, the pinion then being disconnected from A pinion I45 on one of the shafts meshes mounted in and held against endwise. movement in a bearing housing I14 carried by the housing "I. Sleeve I12 is reciprocated in unison with the,sleeves I05 of the main tube unit and the sleeves 62 of the mandrel unit by means of an 'bevel pinion I8I fast on a shaft I82 mounted'in bearings I83 and I84 carried by lateral extensions of a base I85 on which the housing I1I -is mounted. Shaft I82 is connected by a con with thearms I23 of thetube unit 32 and a II of the mandrel unit. Arms I'll are provided with means for connecting the links I13 to the arms at different points in the length of thearms similar to the means providedon the arms I20 and 53 for varying the effective length of the arms. The adjustment should be such that the eifectlve'length of these arms I15 is the same as that of arms I and I3. I

\The two non-reciprocating sleeves I13 are geared to turn together by a sprocket chain I33 running on sprockets m fast on the two sleeves, and these sleeves, and by them the reciprocating sleeves I'I2,- are given the same partial turn during each forward, or non-working, stroke as is given to the mandrels and tothe tube-reciproeating sleeves I05, this beingeifected by a chain I32 running on a sprocket I93 fast on one of the sleeves I13 and on a sprocket I turned by one of the shafts I35 through an overrunning clutch I35. Thechain I is shown as held taut by an idler sprocket I36 and the chain I92 by an idler sprocket I31. By changing the ratio of sprockassv,

m, a mill motor as through shaft m and reductio gearing 2". This motor also drives the die rolls through reduction gearing 2"! and pinion stand 2I5 from which shafts 223, of which one shows in. Fig. 1, extend to the die rolls face of a disc 22'! fast on the end of shaft 2I0 and a crank pin 228 projecting from crank arm 233 fast on the end ofshaft 2I2. Shaft 2I2 is mounted eccentrieally of shaft '2I3. The radius of crank arm 230 is greater than the radius of v the crank formed by disc 22! and pin 228, and

ets I33 and 'IM'the degree of turning may be varied.

Each of the sleeves I12 carries at its end toward the dierolls one of the tube-gripping friction clampsllt. These friction clamps may be.simple two-part clamping devices such as shown by Figs. 16 and 18. One part, 203, ,of each of the clamps is rigidly connected to and extends from} one of the cross-heads I11 and has asubstantially half-cylindrical tube-engaging face, and

' -the other part, 20:, which has a similar halfcylindrical tube-engaging face, is adl stably held to the part 200 by bolts and nuts 202 and spring washers 233.

The function of this exit tube unit is to receive the reduced portion of the tubes and to control the partly reduced tubes during the reduction of the rear end portionthereof and while new tubes are being f'eciprocated and advanced step-bystep to the die rolls by the tube unit 32, keeping the rear end of the partly reduced tubes against the front end of the new tubes. with the clamps properly adjusted, the exit unit turns and reciprocates the partly reduced tubes inzsynchronism v with the turning. and reciprocation of the new tubes by tube unit 32, and also permits slippa e .through the clamps when the partly reduced tubes are given an increment of feed by the new tubes during each non-working stroke and slippage during the working stroke due to the elonga- "as, for example, the well-known sliding block mechanism,might be used for operating thetube i and mandrelreciprocating devicesto give relatively slow working strokes to the tube and mandrel with a considerable portion thereof at a.

linear velocity approximating the peripheral speed of the die rolls, I have found that there j are important advantages in using for this purpose a quick-retum mechanism of the kind generally known as a drag link mechanism, and the quiek-retum mechanism ll shown in Fig. 1 for tkiirinving the oscillating drive shaft 52, is of this d.

This drag m: quick-return mechanism, which 7 the length of link 225 is greater than the greatest distance between the paths of travel of the crank pins 223 and 228. The result of this arrangementis that by the rotation of shaft M0 at a constant angular velocity shaft 2I2 is driven at a varying angular velocity.

The driving member of such drag link mechanism may be driven torotate in either direction, that is, with the driven crank behind the driving crank so that the'link pulls the driven crank, or in advance of the driving crank as shown in Fig. 20 so that the link pushes the driven crank. The term drag link mechanism is commonly applied to both arrangements.

The other end of shaft 2I2 has fast thereon a crank arm 23I from which a link232 extends to a rocking lever arm 233 which is also connected by a link 234 to a lever arm 235 fast on the end the same as though the crank arm 23I had a suitable link connection directly tov lever arm 235, the connection through rocking lever arm 233 being merely a matter of convenience to avoid the necessity of locating the drag link mechanism so far out of line with shaft 52 as it would have to be with a direct connection.

The angular relation between the crank arms" 230 and 23I is such that the slower half of each rotation of shaft 2| 2. moves rocking lever arm 233 and through it lever arm 235 in one direction. and the faster half of each rotation of shaft 2I2 moves these lever arms in opposite direction.

Driving shaft 52 is thus given an oscillation which is comparatively slow in one direction during a timeduring which shaft 2IIl and the die rolls make-more than half a rotation, and comparais shown more in detail in Figs. .19' and 20, comtively quick in'the opposite direction during a Y time less than the timeduring which shaft 2I0 and the die rolls make a half rotation.

And not only does the working stroke correspond to more than of rotation of the die rolls; but with the operative parts of the drag link mechanism and the driving connections therefrom properly proportioned, the linear velocity of the tube and mandrel will be nearly uniform and approximately the same as the pitch velocitvofthe die grooves of the die rolls during a major part of the working stroke. And, furthermore, during most of this major part of the working stroke the tube and mandrel will move with a slightly increasing velocity which compen'sates for the increase in pitch velocity of the tapered die grooves.

- The dimensions of the operative parts of the drag link mechanism of the mill herein shown, are as follows: The-rotational axes of the shafts Illalnd 2I2 are spaced 6% inches aparthorinism is driven at the same uniform angular radius of crank arm 23! is 18 inches, and it is set 100 angularly in advance of crank arm 23!]. The length of connecting rod or link 232 is 48 inches between centers, the length of lever arm 233 is 36% inches between centers, and lever arm 235 is 36% inches long between centers. The osci1-, lating lever arms 53, I20 and I15, which reciprocate the sleeves 62, I05 and I12, respectively,

I have a throw of 52 degrees, and a radial length according to the diameter of the die rollsto give the desired velocity to said sleeves, and to .the

between the velocity curve line and the line X-Y.

The diagram shows that the workingstroke takes place during the time represented by twenty-two of the spaces, numbered 1 to 22 above the line XY, that is, during the time that the die rolls are turning through 220 degrees, and that for as much as fourteen spaces, that is, during the time Y the die rolls are turning 140 degrees, the tube "and mandrel have a substantially constant velocity which during most of this major portion of the working stroke is a slightly increasing velocity. The diagram also shows that most of v the acceleration occurs during the first four time mandrel and tube connected thereto, during the major portion of the working stroke.

With the operative parts proportioned as stated, the'working stroke of the tube and mandrel will extend for a time and distance corresponding to 220 degrees of rotation of the die rolls, and the major portion of the working stroke during which the tube and mandred will have an approximately uniform velocity closely approximating the pitch line speed of the die grooves, will correspond to from about 120 to about 140 degrees of angular motion of the rolls, and acceleration and'deceleration of the tube and mandrel on the working stroke will take place each mostly during 40 ,to 50 degrees of rotation of the rolls; and the quick return stroke will be confined to the remaining 140 degrees of rotation of the rolls. The. die rolls may thus have a swaging, or swaging and finishing, arc

of from '120 to 140 degrees throughout which the die grooves engage the tube, the rolls being clear of the tube during the balance of each rotation, that is, during from 40 to 50 degrees of rotation at the beginning and during 40 to 50 degrees at the end of the working stroke, and during the whole of the return stroke during which the rolls turn 140 degrees;

Fig. 2a shows the die rolls as having die grooves extending over a swaging and finishing arc of 140 degrees of which 100 degrees is the tapered swaging portion for reducing the workpiece and the following 40 degrees is a concentric, or straight, finishing, or smoothing, Portion. The balance of the circumferential groove of each die roll is the gap portion which does not make working engagement with the tube, the tube and mandrel being decelerated while the rolls turn 40 degrees after releasing the tube, then making their forward return movement while the rolls turn 120 degrees andv beingaccelerated at the beginning of the working stroke while the rolls turn 40 degrees before again making working engagement with the tube at the beginning of the swaging arc.

' The reciprocating movements given to the tube and mandrel are represented with approximate accuracy by the tube and mandrel=velocity curve in the diagram, Fig. 21. In this diagram, the velocity curve above the line X-Y represents the uniform time intervals during each of which the intervals of the working stroke during which the die rolls turn 40 degrees, and that most of the deceleration occurs during the last four time intervals of the working stroke; also, that the quick return stroke at variable velocities is accomplished in fourteen of the time intervals, that is, during the time the die-rolls are tuming' through 140 degrees. i The straight line X Y divided by dots into 22 equal parts represents the uniform angular movement of the .die rolls through the 220 degrees during which the tube and mandrel are making their working stroke.

By adjustment of the radial length of the lever arms 53 and I21!v according to the diameter of the die rolls, the length and speed of the strokes of the tube and mandrel are, as before pointed out, adjusted so that during the major portion of the working stroke the velocity of the tube and mandrel are approximately uniform and approximately equal to the pitch-line velocity of the die grooves of the rolls, as the diagram indicates. For die rolls 17 inches inoutside diameter having die grooves with av pitch diameter of about 16 inches for reducing 3% inch 0. D. tubes with a 1%" wall to 2 inches 0. D. and .134" wall, the tube and mandrel will have a working stroke of about 23 inches, and the swaging, or swaging and finishing, are, if 140 degrees, will have a length of about 19% inches on the pitch line. For die. rolls 15 inches in outside diameter, for reducing a 2 inch 0. D. tube 1% inches 0. D., the working stroke will be about 20 inches, and the length of the swaging, or swaging and finishing, arc, if 140 degrees, will be about 17% inches on the. pitch line.

In referring in the preceding paragraph totube and mandrel velocity during the majorportion of the working stroke, the tube velocity referred to is the velocity of the tube as successive pordie rolls and shaft 2! make an angular movement of 10 degrees, the velocity of the tube and mandrel in such time intervals being indicated tions thereof are engaged by the die rolls. .It is especially desirable that the tube and engaging surface of the die rolls move at approximately the same velocity at the time the rolls come into working engagement with the tube at the beginning of each reducing operation.

The mill is provided with suitable guides, or steadiers, for centering and supporting the tubes when the tube unit is in a retracted position and means for moving the guides to clear the tube unit asvthe unit advances, and with guides, or

steadiers, for supporting and steadying the mandrel bar when the tube unit is in a forwardposition, and means for moving such mandrel guides clear of the tube unit as the unit is retracted. The mill illustratedhas one set of tubeguides 240, of which one appears in Fig. 2 in uppeif 'position, and an operating motor- 2 therefor, and

one set of mandrel bar guides 242, of which one is shown in Fig. 2 in its lowered guiding position, and

anoperating motor 243 therefor, of a kind fully described and claimed in my co-pending applicaproportionately by the length of the vertical lines tion Serial No. 501,104, filedseptember 8, 1943.

or, before engaging clutch In the operation of the mill, throughout the major portion of each working stroke of the tubes and mandrels, during which they move at sub-* stantially constant velocity, a length of tube is pressed between the swasing p rtions, or swaging and finishing portions, of the grooves of the die rolls, and thereby progressively reduced from the original 0. D. and wall thickness at the beginning of the stroke to the final O. D. and wall thickness atthe end of the stroke. The tubes are then released by the die rolls, and after deceleration the tubes and mandrels make a quick forward return stroke during which they are given a partial turn and the tube unit 32 is moved forward to give an increment of feed to the tubes. This short feeding movement, of from 1; inch to inch of the tube unit is a very slow movement spread over the entire length of the return stroke and is consequently performed without shock. During the working stroke the tube unit housing is held against movement. The partial turning of the tubes and mandrels is also spread over the entire return stroke.

'When the tube unit 32 has been advanced to its extremeforward position, as shown by full lines in Figs. 1 and 2, at which time an unreduced a rear end portion of the tubes will project from the rear side of the roll stand housing 40, the mill is stopped and the unreduced ends of the tubes are clamped between the clamping members 41 and 43. The tubes are then disconnected from the sleeves I05 of the tube unit 32 and the mandrel Instead of operating as a duplex mill, reducing two tubes at the same time, the mill may be operated to reduce only one tube at a time,.either side of the mill being used for such single tube operabar is disconnected from mandrel unit 3|. Clutch A I53 of the tube feedmechanism having been disconnected, motor i65 is then operated to move tube unit 32 backward to its extreme retracted position indicated by dotted lines in Fig. 2, and the mandrel bar isdrawn back, by any suitable ward end of the mandrel is back of the tube clamp III] of tube unit. 32. Two new tubes are then I brought into position in the mill and moved backward and theirrear ends are entered into and secured in the clamps Ill, and the tube-guides 240 are moved down into position to support the tubes. The mandrel bar is then moved forward back to its original position as determined by the stop 14. Then, clutch I53 having been again engaged and tube clamping members 48 having been raised, the mill may be again started in operation,

I53 and raising clamping members", motor I55 may be operated to move tube unit 32 forward'to move the new tubes unto the partially reduced tubes. Until the new tubes have been advanced to-bring their front ends into engagement with the rear ends of the previous partially reduced tubes, the partially re duced tubesare merely reciprocated backward and forward and given their partial turns by exit tube unit 35, and during this time. these partially reduced tubes are not fed forward and unreduced portionsther'eof are not'brought into reducing when, however, ;the new tubes have been adyanced so that their front ends engagethe rear ends ofthe previous tubes, then the previous partly reduced tubes are on each return stroke pushed by the new tubesand given the same inbeing on opposite sides of the mill. 35-

means not shown in the drawings, until the forcontact with the die grooves of the die rolls.

crement of feedas is given to-the new tubes'by the forward feeding movement of the tube unit then proceeds by'c'ontinued operation of the mill until the tube unit 32 again reachesits forward position shown by full lines in Figs. 1 and 2.

'32.' The reduction of the previous tubes is thus --.complet.d. and the" reduction of the new tubes,

.normal to the lever.

253 are each mounted to slide-bu a pair of vertical' rods 26!] extending downward from a tion, and many features of the duplex mill illus its advantageous results. The counterbalancing means may be applied to different reciprocating parts of the mill. In the mill shown by the drawings, springs are used as the resilient members of the counterbalancing means. Most desirably,

and as shown, the mill is provided with four sets; or pairs, of these springs, the springs of two of the sets being connected to the oscillating levers 53 of the mandrel unit 3|, and the springs of the other twofsets being connected to the oscillating levers I15 of the exit tube unit 35, as indicated in Figs. 2 and 16. The construction is the same for both units, and'Figs. 2, 3, 4 and 5 may be considered as showing the construction for one of the sets of either unit, the two sets of each unit Referring now to Figs. 2, 3,4 and 5, two helical tension springs 250 and 25I extend vertically I upward from

cross-heads

252 and 253 and have their upper ends connected by

links

254 and 255 each to one of two arms 253 and 25'! extending from diametrically opposite sides of the hub of one of the oscillating levers 53 in a diameter The cross-heads 252 and bracket 26l secured tothe base 5|. Each crosshead is mounted on its rods 260 by means. of exteriorly threaded sleeves 262 adjustable in threaded openings in the cross-head and locked in adjusted position by lock nuts 263. Upward movement of the cross-head is limited by engagementof the upper ends of sleeves 26 2 with buffer rings 2 of rubber or other suitable cushioning material on the rods 260. i

When the oscillating'lever 53 is in its midway position as shown in Fig. 4 with the arms 256 and :25! horizontal, both of the cross-headswill be in upper position with neither of the springs under tension. During the last half of the working stroke, spring 250 will be fully extended, and

in being extended it will resist the inertia forces during deceleration .of lever 53 and the reciprocating and oscillating parts connected to movetherewith. And during this last half of the working stroke spring 25l will remain unextended, the

spring and cross-head moving downward. During the first half of the following forward nonworking stroke, acceleration will be aided by the.

tension of spring 250, and cross-head 253 will be returned to its upper position without extension of spring 25L -Then dui'ing the last half of the non-working stroke, spring 25l will be extended, resisting deceleration, and spring 250 will remain unextended moving downward with its cross-head 252. In the first-half of the sucbeeding working stroke, acceleration be: aided spring 250.

by spring 25L and cross-head 252 will be returned to its upper position without extension of Although, as stated, complete balancing is not obtainable since the mass energy of the reciprocating and oscillating parts varies on the working and non-working strokes, the results obtained by the use of suitable counter-balancing means, such'as the springs shown, the springs being of proper strength, are of great advantage in obtaining smoother operation of the mill at the comparatively high speed at which it operates and reduction of shock on the machine frame, in reducing 'the effort required of the quick return mechanism and other parts in driving the reciprocating and oscillating parts of the mill, in reducing the power required for operating the mill,

and in maintaining close registration between the tapered mandrels and thetapered die grooves during the working strokes by reducing the-inertia effect of the reciprocating mandrel rods.

As will be apparent from the foregoing description, the new mill has many featuresof construction contributing to the high efficiency and production capacity of the mill andthe quality of its product. The mass of reciprocating parts is largely reduced by having the mandrel bars and the tubes secured to relatively light reciprocating parts mounted in non-reciprocating housings and reciprocated by means of lever arms cillating on axes fixed in the housings, the mandrel unit housing, being stationary and .the tube unit housing being moved only with a small slow step-by-step movement for feeding the tubes relatively to the mandrels during the non-workin strokes. The mandrels and tubes are positively reciprocated, and synchronous movement bechines differing otherwise from that shown by the drawings. As stated, many features of the invention may be embodied in single reducing tween the mandrels and tubes and the swaging portions of the die rolls is secured by reciprocating the mandrels and tubes by means of a draglink quick-return driving mechanism whereby at the beginning of each working stroke the movement of the mandrels and tubes. is accelerated to approximately the pitch line speed of the die grooves of the rolls before the rolls make working engagement with the tubes, and whereby during a major portion of each relatively slow working stroke the mandrels and tubes are moved at a substantially constant but slightly increasing speed corresponding to the die groove pitch line speed of the rolls. The mandrels and tubes are reciprocated independently but in unison except for the slightly greater movement of the tubes during theforward non-working strokes due to the forward feed movement of the tube unit housing on which the tube reciprocating oscillating lever arms have their axis. The inertia effect of the oscillating shafts by which these oscillating lever arms, or rocker arms, are actuated is much less than that of reciprocating parts of much less weight. These and other contributing features will be specifically defined in the claims. The operating speed of the mill with die rolls 15" to 18" in diameter is from 60 R. P. M. upward of the die rolls, depending on the diameter of the die rolls.

It is to be understood that the invention is not limited to the exact construction, arrangement and combinations of parts shown by the drawings and to which the foregoing description has been largely confined, but that it includes changes and modifications thereof within the. claims. It will also be understood that certain features of the invention as claimed may be employed independently of other features thereof and iammills adapted for operating on only one tube or other workpiece at a time.

What is claimed is:

1. In a Pilger mill of the type wherein. a pair of gapped die rolls mounted to rotate continuously in one direction about fixed axeswork on successive portions of a reciprocating workpiece on successive reciprocations, the improvement which consists in providing workpiece-reciprocating means mechanically geared with and positively timed with the rolls and mechanically connected with a workpiece -gripp member and constructed and arranged to accelerate the movement of the workpiece from its position of rest cating means mechanically geared with and posi-* tively timed with the rolls and mechanically connected with a workpiece-gripping member and constructed and arranged to accelerate the movement of the workpiece from its position of rest at the beginning of each working stroke to approximately the pitch-line speed of the die portion of the rolls before working engagement between the workpiece and the rolls occurs and then to maintain the speed of the workpiece constant during a. major portion of the working stroke, and positively-operated step-by-step feeding means whereby the workpiece is given an rotate continuously in one direction about fixed increment of feed during each return stroke.

3; In a tube reducing Pilger mill of the type wherein a pair of gapped die rolls mounted to axes work on successive portions of a reciprocating tube on successive reciprocations, the improvement which consists in providing tube and mandrel reciprocating means mechanically geared with and positively timed with the rolls and mechanically connected with a time-S pp member and a mandrel rod gripping member and constructed and arranged to accelerate the movement of the tube and mandrel from'their positions of rest at the beginning of each working stroke to approximately the pitch-line speed of the die portion of the rolls before working engagement between the tube and the rolls occurs and then to maintain the speed of the mandrel and tube constant duringa major portion of the I working stroke, and positively-operated step-byl step feeding means whereby'the tube is given an increment of feed during each return stroke.

4. In a Pilgermillofthe typewhereinapair" of gapped die rolls mounted to rotate confirm-- ously about fixed axes in one direction work on successive portions of a reciprocating workpiece on successive reciprocations, the t which consists in providing a drag-link quickreturn driving-mechanism for-reciprocating the workpiece with a relatively slow'worklng stroke which extends over atime during which the die rolls make substantially more than half a pitch line speed of the the die portions of the rolls, to move the workpiece at approximately such speed during a major portion of the working stroke, to decelerate the speed of the workpiece to rest during the last part of the working stroke after the rolls have released their grip on the workpiece, and then to move the workpiece forward through the gap portions of the rolls into position for the next working stroke.

' 5. Ina Pilger mill having a pair of gapped rolls mounted to rotate continuously about fixed axes and providing working surfaces having a tapered portion for reducing the workpiece followed by a straight portion for smoothing the reduced workpiece and then by a gap portion, the improvement which consists in providing workpiecereciprocating means mechanically geared with and positively timed with the rolls and mechanically connected with a workpiece-gripping memher and constructed and arranged so that during each operating cycle the workpiece is moved through thegap portion of the rolls from rest to approximately the peripheral speed of the working surfaces of the rolls, then is engaged by the tapered portion and straight portion 01? the rolls in succession, and then is brought to rest again and returned through the gap portion of the rolls into position to begin a new cycle, and positively operated step-by-step feeding means whereby the workpiece is given an increment of feed during each return stroke. a

' 6. In a Pilger mill having a pair oi gapped rolls reciprocating member from their positions of rest at the beginning of each working stroke to approximately the pitch-line speed of the die portions of the rolls before working engagement occurs andthen during a major portion of the working stroke at a speed approximating the pitch line speed of the die grooves of the rolls, and means forgiving an increment of feed to the'tube-reciprocating member during each return stroke.

8. A tube reducing mill, comprising in combination a pair of gapped die rolls having tapered die grooves mounted to rotate about fixed axes,-

rocating member and the tube-reciprocating member from their positions of rest at the beginning of each working stroke to approximately the pitch-line speed of the die portions of the rolls before working engagement occurs and then mounted to rotate continuously about fixed axes ber and constructed and arranged so that dur ing ,the first part of each working stroke the workpiece is moved through the gap portion of l the rolls from rest to approximately the peripheral speed oi. the working surfaces of the rolls, then during the major portion of the working stroke corresponding to 120 or more degrees of the cycle is engaged by the tapered portion and straight portion of the rolls in succession, then during the balance of the working stroke is brought to rest again, and during the remainder of the cycle is returned through the gap portion of the rolls into position to begin a new cycle, and positively operated step-by-step feeding means whereby the workpiece is given an increment of feed during each return stroke. 7. A tube reducing mill, comprising in combination a pair of gapped die rolls mounted to rotate about fixed axes, means for continuously rotating said rolls, a mandrel co-operating with the die grooves of said rolls, .a mandrel-reciprocating member, a tube reciprocating member, and a quick-return driving mechanism mechanically connected with the rolls and with the mandrel-reciprocating and tube-reciprocating members for reciprocating the mandrel-reciprocating member and the tube-reciprocating member with during a major portion of theworking stroke at a speed approximating the pitch line speed of ;bination a pair of gapped die rolls having tapered die grooves mounted to rotate about fixed axes, means for continuously rotating said rolls, a tapered mandrel cooperating with the die grooves of. said rolls, and a drag-link quick-return driving mechanism for reciprocating the mandrel with a relativeLv slow working stroke and a quick-return stroke, said driving mechanism driving the mandrel during the major portion of the working reciprocating member and the tube-reciprocating member with a relatively slow working stroke and a quick return stroke and for moving them during a major portion of the working stroke at a speed approximating the pitch line speed of the die grooves of the rolls, and means for giving an increment of feed to the tube-reciprocating member during each return stroke.

11. A tube reducing mill, comprising in combination a pair of gapped die rolls having tapered a relatively slow working stroke and a quick return stroke, said driving mechanism moving the mandrel-reciprocating member and the tubedie-grooves mounted to rotate about fixed axes, means for continuously rotating said rolls, a tapered mandrel cooperating with the die grooves of said rolls, a positively acting quick-return driving mechanism, a rock shaft operated by said driving mechanism to have a relatively slow turn in one direction and a quick turn in the other direction, and a lever arm on said shaft for reciprocating the mandrel.

12. A tube reducing mill, comprising in combination a pair of g'apped die rolls having .tapered.

die grooves mounted to rotate about fixed axes, means for continuously rotating said rolls, a

- tapered mandrel cooperating with the die grooves .of said rolls, a mandrel-reciprocating member to Y which th mandrel rod is secured, a tube-reciprocating member to which the tube is secured, a

longitudinally movable housing in which said tube-reciprocating member is mounted, a drive shaft, driving mechanism for oscillating said shaft, a lever arm receiving oscillatory movements from said drive shaft for reciprocating the mandrel-reciprocating member, a longitudinally extending rock shaft operated by said drive shaft, a sleeve on said rock shaft splined thereto to be turned thereby and mounted for oscillation in said housing, a lever arm pivotally mounted in said housing and geared to said sleeve to be oscillated thereby for reciprocating the tube-reciprocating member, and means for giving an increment of feed to said housing during each return stroke.

l3. A tube reducing mill, comprising in com binat'ion a pair of gapped die rolls having tapered die grooves mounted to rotate about fixed axes,

. means for continuously rotating said rolls, a

nally extending rock shaft operated by said drive shaft at a higher angular velocity than the drive shaft, a sleeve on said rock shaft splined thereto to be turned thereby and mounted for oscillation 16. A tube reducing mill, comprising in combination a pair of die members having tapered die grooves mounted to turn about 'fixed' axes, a tapered mandrel cooperating with the'die grooves of said members, a rotatable mandrel-reciprocating member to which the mandrel rod is secured, a rotatable tube reciprocating member to which the tube is secured, a longitudinally movable housing in which said tube-reciprocating member is mounted, a drive shaft, driving mechanism for oscillating said shaft, a lever arm receiving oscillatory movements from the drive shaft for reciprocating the mandrel-reciprocating 'member, a longitudinally extending rock shaft operated by said drive shaft, a sleeve on said rock shaft splined thereto to be turned there by and mounted for oscillation in said housing, a lever arm pivotally mounted in said housing and geared to said sleeve to be oscillated thereby for reciprocating the tube-reciprocating member, means for giving an increment of feed to said housing during each return stroke, means including a one-way clutch operated by said rock shaft v for turning the mandrel-reciprocating member during each return stroke, and means including a one-way clutch operated by saidrock shaft pered mandrel cooperating with the die grooves in said housing, alever arm pivotally mounted in said housing and geared to said sleeve to be I oscillated thereby at the same angular velocity v as the first-mentioned lever arm for reciprocatingnation a pair of die members having tapered die grooves mounted'to turn about fixed axes, a'

tapered mandrel cooperating with the die grooves of said members, a mandrel-reciprocating'memher to which the mandrel rod is secured, a tubev reciprocating member to which the tube is secured, a longitudinally movable housing in which for turning the tube-reciprocating member during each return stroke.

17. A tube reducing mill, comprising in combination a pair of die members having tapered die grooves mounted to turn about fixed axes, a taof said members, a rotatable mandrel-reciprocating member to which the mandrel rod is secured, a rotatable tube-reciprocating member to which the tube is secured, a longitudinally extending rockshaft, means for oscillating said shaft in time with the rotation of the die rolls, means operated by said shaft for reciprocating the tubereciprocating member, means for reciprocating the mandrel-reciprocating member, and means whereby the tube-reciprocating member and the mandrel-reciprocating member are turned in unison by said shaft during its oscillations inone direction.

18. A tubereducing mill, comprising in combination a pair of gapped die'rolls having tapered die grooves mounted to rotate about fixed axes,

atapered mandrel cooperating with the die grooves of said rolls, a rotatably mounted mandrel-reciprocating member to which the mandrel said tube reciprocating member is mounted, a

drive shaft, driving mechanism for oscillating said shaft, a lever arm receiving oscillatory movements from said shaft for reciprocating the mandrel-r'eciprocating member, a longitudinally extending rock shaft operated by said drive shaft, a sleeve on said rock shaft splined thereto to be turned thereby and mounted for oscillation in said housing, a lever arm :pivotally mounted in 'said housing and geared tosaid sleeve to be oscillated thereby for reciprocating the tube-recipro- 1s. A tube reducing mill as claimed in claim 14,

j in which the longitudinally extending rock shaft 1 is driven by the drive shaft through speed-up gearsand thesecond mentioned lever arm is operated by the rock shaft through speed-down gears.

rod is secured, a rotatably mounted tube-reciprocating member to. which the tube is secured, driving mechanism for the mandrel-reciprocating member'and the tube-reciprocating member I for moving them from rest at the beginning of each working stroke to approximately the pitch line speed of the die grooves of the rolls beforev working engagement occurs and during a major portion of the working stroke at a speed approximating the pitch linespeed of the die grooves of'the rolls, and means for turning said members during each return stroke.

19, A tube reducing mill, comprising in combination a pair of capped die rolls having tapered die grooves mounted to rotate about fixed axes,

a tapered mandrel cooperating with the die grooves of said rolls, a rotatably mounted mandrel-reciprocating member to which the mandrel and the tube-reciprocating member with arelatively slow working stroke and quick return