US2340517A - Cross rolling mill - Google Patents

Description

Feb. 1, 1944. s. E. DIESCHE R I 2,340,517

' CROSS ROLLING MILL Filed April 15, 1942 2 Sheets-Sheet 1 IN VENTOR.

1944; s. E. DIESCHER GROSS ROLLING MILL Filed April 15, 1942 2 Sheets-Sheet 2 mm NM M I HWM| mm b g K Q a a Q S QM. mm 4 Q N RN 5 A; Afro/WE) Patented 1-251, 1944 Dlescher Tube Mills, Inc corporation of Delaware Beaver Falls, Pa., a

Application April 15, 1942, Serial No. 439,019

19 Claims. (01'. 80-13) This invention relates to cross-rolling mills of that kind in which a pair of rotary guide discs (or in some cases a single disc) engage the workpiece as it is rotated and advanced between a pair of helically-acting skewed reducing rolls, commonly termed cross-rolls. Cross-rolling mills of this kind are shown in the S. E. Diescher Patents Nos. 1,586,975, 1,870,209, 2,031,761, and 2,042,832.

The object of the invention is to provide a cross-rolling mill of this kind in which the working parts may be held in their relative positions with such rigidity as to provide maximum accuracy of gauge or wall thickness of product as Well as maximum life of work engaging members.

The requirements of accuracy in maintenance of positioning ofthe working parts are especially exacting when thinner wall product is being made. For example, a tube specified to have a wall thickness of gauge, 1. e., 0.720", may actually become 14 gauge, 1. e., 0.0830", if at a less heated portion of a workpiece the main rolls be forced 0.011' from their normal positions. Such a spread would be drastic, but at that it may occur at the end of the passage of a tube, the rearmost part of which may have become chilled. Even a lesser spread than this may lead to crowding of 1 the steel between the main roll-and its companion guide disc, which would mar the lip of the guide a disc groove and perhaps also the face of-the main roll. Such cases involve shut-downs for renewal of working members.

In the operation of such mills, whether piercing mills, for producing tubular blanks, or hollows.

from cylindrical workpieces, or tube reducingv mills for reducing the wall thickness of and elon-" gating tubular blanks, it is highly desirable, in order to obtain uniform diameter and wall thickapplication to such ness, and also smooth surface product, and to r avoid excessive wear on parts of the mill, and

especially on the work-engaging surfaces of the guide discs and rolls and of the side edges of the discs, that both the guide discs and the rolls shall maintain their positions during the rolling p ration without give or any weaving motion or vibration. The rolls and guide discs are driven at a comparatively high R. P. M., and the workengaging surfaces of the guide discs move at correspondingly high speed in pressure contact with the rapidly rotatingand longitudinall advancins workpiece. Under the. hi h pressure to which they are subjected, the reducing rolls tend toback away from the pass line, and the guide discs, under the force exerted on them by the rapidly rotating workpiece, tend to move axialiyfrom theirnormal andproperpositlons andifsuchas work members no change from their relative idle movements are permitted bythe mountings of the rolls and discs, a harmful weaving movement thereof results. Such in and out motion of the rolls and axial motion of the discs, when the discs are set, as they should be, with close clearance between a peripheral edge thereof and one of the cross-rolls, leads to harmfui 'spreading between the discs and the rolls and to undue wearof the work-engaging faces of the discs and rolls which in turn results in impairment of the surface finish of the product. Give, or yielding, in the mountings of the rolls and discs may result from slight flexibility in parts of the machine and from clearances between machine parts taken up as load is applied, and with workpieces that are not uniformly heated there will be such give to a harm-- in] degree in spite of great care and accuracy in the design and construction of the mill. 1

A difliculty of the kind'referred to has been due to. failure of the guide discs to resist under operating pressures slight displacement from their adjusted positions. Such displacement of the guide discs is prevented according to the present invention, and maintenance of their position bearing steadily on the workpiece between the cross-rolls attained, by the provision 01 means whereby preloading pressure is applied to the disc shafts sufilcient to take out all clearances and harmful yields in the shaft mounting parts. -It

is desirable in a mill according to the present invention, that the cross-rolls shall also be preloaded to take up clearances and harmful yields. Cross-rolling mills of the kind to which the invention relates have. been equipped heretofore with means for partially so preloading the crossrolls, and no claim is, therefore, made in this partial preloading of the Disc preloading according to of course, be employed to adcross-rolls Der se. the invention may,

vantage without the preloading of the main rolls,

that is, the cross-rolls, but for best results it is desirable that both discs and main rolls shall be preloaded. I

The preloading of both .the main rolls and the guide discs should be of such effect that with normal variations of temperatures of the work-.

piece and normal variations of loadlng'of the positioning occurs. It will be readily understood that in adjusting a guide disc to its correct relationship to the face of its companion main roll this adjustment can safely be made only when the mill is idle. Under previous conditions, when a workpiece enters the mill all clearances among the bearing andhousing screw members of line 1-4 of Fig.2;

of the main rolls will be taken up by a spread to that amount at the main rolls and, moreover, whatever flexibility there may be in the main parts of the mill framework will reflect a, further spread of the main rolls. Whatever the total of this main roll spread is will have added thereto the give arising from similar sources in the companion guide disc mountings. Thus it can be seen that the give of guide discs and main rolls have an additive effect in creating a widening of the gaps between the main roll faces and the guide disc lips, which gaps, as learned in practice, should be no more than to permit guide disc rotation, whether the mill is under load or is idle, with but enough clearance at the companion roll face as to insure freedom from contact therewith,

In the cross-roll and guide disc rolling procedure, each of the two main rolls feeds the metal being rotatively worked to the lip of a guide disc that is'set in a manner as directly as possible to receive and then divert the flow of .metal crosswise of the. guide disc groove. As

each main roll feeds directly toits own guide disc, that guide disc is referred to herein as being the companion disc of its respective main roll or vice versa. Pressures tending to spread the main rolls in the type of mill herein dealt with exceed what might ordinarily be expected and, moreover, vary in the course of the working of a workpiece even when the workpiece is uniformly heated throughout its extent. This condition arises from the novel ability of the cross-roll guide-disc type of mill to correct inequalities in wall thicknesses of the workpiece being worked. It is obvious that at a position in a workpiece where such inequalities are greatest, the pressurev tending to spread apart the main rolls must likewise be greatest, but quite contrary to what might be expected, the spreading tendency at places along the workpiece where the piece has a measure of eccentricity of bore which is greater than at other places, will reflect a pronounced spreading tendency at the main rolls. This creates a substantial additional tendency locally to spread the main rolls, which to that degree increases the wall thickness of the tube at such places although still keeping the wall thickness uniform cross-sectionwise.

The cross-roll and guide disc type of mill is generally recognized as affording the only seamless tube making procedure possessing the ability to correct gauge inequalities, The preloading of the working members as herein described enhances that ability.

A full understanding of the invention can best be given by a detailed description of an illustrative embodiment of the'invention, and such a description will now be given in connection with the accompanying drawings showing a tube elongating cross-rolling mill equipped with guide discs and having preloading means in accordance with the invention.

In said drawings- Fig. 1 is a partial view looking toward the entrance end of the mill sectioned on the plane Fig. 2 is a section taken on line 2-2 of Fig. 1 Fig. 3 is an enlarged sectional view of the lower guide disc and its mountings and adjacent parts; and I Fig. 4 is a still further enlarged sectional detail view taken on line 4-4 of Fig. 3.

The drawings show a tube-elongating mill of the kind disclosed in the S. E, Diescher Patent 1,870,209: The mill has a pair of helically acting cross-rolls In in the pass between which a tubular blank H which is being reduced is rotated and given a helical advancing movement on a mandrel l2, and a pair of peripherally grooves guide discs l5 mounted on opposite sides of the pass line with their axes extending at, or approximately at, right angles to the pass line and the rims of the discs extending between the cross-rolls to engage the tubular blank.

The cross-rolls are skewed, being mounted with their axes inclined to each other and to the line of feed of the blank between them. Their suitably driven shafts are journalled in bearing blocks I'I slidably mounted in the mill frame and adjustably moved toward or from each other by means of screws 2|. The guide discs, as shown in Fig. 3 for the lower disc, are each carried by a shaft 22 journalled in a split bearing shell, or housing, 23, the shaft being driven through universal coupling 24 to rotate the disc in the direction of longitudinal movement of the blank or workpiece at a peripheral speed materially in excess of the longitudinal movement of the workpiece. Each disc is detachably but rigidly mounted on a flanged hub 25 at the overhanging inner end of its shaft 22.

The guide discs are spaced apart sufficiently to permit the tubular blank, under the wall-reducing pressure of the cross-rolls, to bulge somewhat away from the mandrel as described in the S. E. Diescher Patent 1,870,209, and as shown in Fig. 3 of. the drawings hereof. The peripheries of the discs are grooved, or concavely curved transversely, for engaging the bulging wall of the blank as it comes from one of the cross-rolls and deflecting and directing it toward the other cross-roll, and each disc is set with its rim closely spaced from the cross-roll which rotates the tubular blank toward the disc, as shown and described in the S. E. Diescher Patent 1,951,348.

The bearing shells 23 are adjustable longitudinally to bring therims of the guide discs into desired relationship with the cross-rolls. shown in Fig. 3 for the lower guide disc, the shaft 22 of each disc is mounted within its shell 23 by a roller, bearing 30 adjacent the overhanging disc and a roller bearing 3| near the other end of the shell, these hearings taking the radial load on the shaft, and by a double ball bearing 32 to take the longitudinal thrust on the shaft. The shell 23 is slidably mounted for longitudinal movement on a vertically adjustable frame or stool 33. Extending from the shell 23, is alug 35 from which a bar 36 extends parallel with the shaft, ,the bar having a threaded portion which is engaged by a worm nut 31 rotatably mounted and held against axial movement in the frame and which is rotated by a worm 3B turned by means of a hand wheel, not shown, or otherwise. By this worm and screw rigging the guide disc may be adjusted axially as desired.

The endwise thrust on each disc shaft is thus taken by the ball bearings 32 and transferred to the shell 23 and thence through screw bar 36 and worm nut 31 to the frame 33. There will be some yield and clearance to take up in these partsunder load. This results, as stated, in a slight weaving of the discs across the pass between the roll-faces. To take up these clearances and to preload the yielding parts to the extent of the longitudinal movement of the guide discs under load, the'mill is provided with thrust units which act directly against the overhanging ends of the disc shafts.

. fit the end of the spindle.

I is moved by means of the worm The prel ading thrust unit for the shaft of the lower guid disc is shown in section in Fig. 3, and the mill shown has a similar construction for the upper disc shaft. Referring especially to Fig. 3,

a hollow spindle 401s mounted, in line with the' disc shaft 22 and on the other side of the disc, within a split bearing shell, or housing, 4| which is slidably mounted for longitudinal movement on screw rigging shown might be provided for forcpared to a suitable hydraulic rigging, with which,

the frame 33. The spindle 40 is mounted by means of longitudinally spaced roller bearings 42 and 43 and a ball thrust bearing 44. Supportedto be capable of limited universal movement within the hollow spindle 40, is a thrust spindle 50 having spherically curved ends. The outer end of this thrust spindle 50 seats against a cupped seat fixed in the'outer end of hollow spindle Ill and which is spherically curved to fit the end of spindle 50. The inner end of spindle 50, when the shell ll is moved'in to operative position, bears against a cupped end piece 52 at the disccarrying end of shaft 22, the spindle engaging face of this end piece being spherically curved to The end piece 52, instead of being formed integral with the shaft 22 or hub 25, is most desirably a separately formed piece detachably secured to the end of the shaft or hub.

The thrust spindle 50 is of less diameter than the bore of hollow-spindle 40 so that the thrust spindle is free to float universally inside the hollow spindle in the event of, slight mis-alignment of the end of shaft 22 and spindle seat 5|. The end of the thrust spindle is keyed to the cupped end piece 52 to cause the spindle to rotate with r the disc shaft. As shown, a key 53 is set into and secured in a slot in the end of the spindle and also enters a slot in the cupped end piece,

there being clearance between the keyand the slot in the end piece so that the key shall not interfere with any needed universal movement of the spindle over a range sufficient to take care of any likely misalignment. At the outer end of the hollow spindle 40, there-is a key 54 seated in slots in the hollow spindle and in the cupped seat 5| and in the end of the thrust spindle, whereby the hollow spindle is caused to rotate I with the thrust spindle in synchronism with the disc shaft 22. This key also is loosely fitted in the slot in the thrust spindle so as not to interfere with the universal movement of the spindle.

The bearing shell 4| might be moved longitu-' dinally in its seat on the frame 33 by any suitable force-applying means. As shown, it is moved by a worm and screw rigging similar to that provided for the shells 23, the shell ll carrying a lug 55 from which a bar 56 extends parallel ,with the spindle 40,- this bar having a threaded portion which nut 51 rotatably mounted and held against axial movement in the frame 33 and which is rotated is engaged by a wormby a worm 58 turned by a hand wheel, not shown,

or otherwise.

To preload/ the disc shaft, the bearing sleeve ll ging to bring the end of thrust spindle 50 into engagement with the cupped face -of block 52,

and then further moved and forced inward to' force the end of the thrust spindle against the block 52, thereby to preload the entire disc shaft thrust rigging itself and its worm and screw operating means.

Obviously, means other than the worm and and screw righowever, the extent of the preloading thrust could bemore definitely fixed and maintained.

The operating means provided for moving the shaft bearing shells 23 for adjusting the position .of the discs with relation to the rolls, and for moving the thrust spindle bearing shells 3| for applying preloading pressure to the disc shafts, serve also, in the construction shown, for separating the bearing shells-for the purpose of changing discs, the end pieces 52 being removed and the lower disc-carrying frame being lowered for this purpose and the upper disc-carrying frame raised.

For loosely retaining each of the thrust spindles 50 in its hollow spindle 40 at'times when one of the disc shaft mountings and the'opposing thrustspindle mounting are moved apart for disc changing, a threaded plug 60 is provided which is screwed into the wall of the hollow spindle and projects down into a short slot in.

the thrust spindle.

Although the axial thrust exerted on the guide discs by the rapidly rotating workpiece is in opposite directions on the two discs, the preloading i pressure may, as in the mill illustrated, be applied in the same direction to both disc shafts, since it-is immaterial in which axial direction the pressure-is applied, so long as it is sufiicient to take up the clearances and harmful yields in the mounting parts and the pressure applying means will hold against any counter pressure in the operation of the mill.

As stated, it is desirable that, in addition to the preloading of the guide discs, preloading means i be provided also for the cross-rolls. Such means the roll shafts are built under close tolerances not requiring to be taken up by preloading, the preloading of the bearing blocks and frame being all that is required.

Four of the jacks 10 are provided, one at the top and one at the bottom of the bearing blocks on the entry side of the mill, and one at the top and one at the bottom of the bearing blocks on the exit side of the mill. Each Jack, as shown and most desirably, is formed by a block bored to provide a hydraulic cylinder closed'at one end and to contain a plunger suitably packed, as by means of a cup packing at its fluid pressure end as is usual for a single acting plunger. Each cylinder has an inlet opening II at its inner end to which pressure fluid is supplied through suitable connections. The jacks are held in place by the water shields 12 which have holes bored through them corresponding to the diameters ofthe cylinder base and the plunger end. The cylinder assemblies must be readily removable, for otherwise renewal of rolls maygbe delayed.

It is to be understood that the invention is not-to be limited to tube elongating mills of the which the foregoing de..

rigging of the blocks loading means according to the invention may be applied to other guide disc cross-rolling mills of the kind referred to, whether for operating on tubular or solid workpieces, including piercing mills for producing tubular blanks, or hollows, from solid cylindrical workpieces. It is to be understood, further, that the invention is not to be limited to the preloading means shown in the drawings, but that it includes changes and modifications thereof within the claims.

What is claimed is: i

1. In a cross-rolling millhaving a pair of helically acting skewed reducing rolls and a rotary guide disc mounted on a driven shaft to bear peripherally on the workpiece between the reducing rolls, preloading means for applying to the guide disc axially thereof pressure sufficient to take out clearances in and harmful yields of the shaft mounting parts.

2. In a cross-rolling mill having a pair of heli-- cally acting skewed reducing rolls and a rotary guide disc mounted on a driven shaft to bear peripherally on the workpiece between the reducing rolls, preloading means for applying to the shaft of the guide disc axially thereof pressure sufficient to take out clearances in and harmful yields of the shaft mounting parts. 7

3, In a cross-rolling mill having a pair of helically acting skewed reducing rolls and a rotary guide disc mounted on a driven shaft to bear peripherally on the workpiece between the reducing rolls, preloading means for applying to the shaft of the guide disc axially thereof pressure sufficient to take out clearances in and harmful yields of the shaft mounting parts, lsaid preloading means comprising a thrust member mounted for engagement with an end of the guide disc shaft and means for forcing the thrust member against the end of theshaft.

4. In a cross-rolling mill 'having a pair of helically acting skewed reducing rolls and a rotary guide disc mounted to bear peripherally on the workpiece between the reducing rolls with its rim closely spaced from the reducing roll whichrotates the workpiece toward the disc; preloading means comprising a thrust member mounted for engagement with an end of the guide disc shaft and means for forcing the thrust member against the end of the shaft.

5. In a cross-rolling mill cally acting skewed reducing rolls and a rotary guide disc mounted to bear on the workpiece between the reducing rolls, the guide disc being carried by the overhanging end of a shaft journalled within a longitudinally adjustable housing; preloading means comprising-a thrust member mounted for engagement with the overhanging end of th guide disc shaft and means for forcing the thrust member against the end of the shaft.

6. In a cross-rolling mill having a pair of hell-- cally acting skewed reducing rolls and a rotary guide disc mounted to bear on the workpiece between the reducing rolls, the guide disc being carried by the overhanging end of a shaft journalled within a longitudinally adjustable housing mounted on a vertically adjustable frame; preloading means comprising a thrust member mounted forengagement with the overhanging end of the guide disc shaft and means for forcing the thrust member against the end of the shaft.

'7. In a cross-rolling mill having a pair of helically acting skewed reducing rolls and a rotary guide disc mounted to bear on the workpiece having a pair of heuhousing and a worm nut on 'said screw bar and held against axial movement by the mill frame and a worm for turning said nut; preloading means comprising a thrust member mounted for engagement with the overhanging end of the guide disc shaft and means for forcing the thrust member against the end of the shaft.

8. In a cross-rolling mill having a pair of helically acting skewed reducing rolls and a rotary guide disc mounted to bear on the workpiece'between the reducing rolls, the guide disc being carried by the overhanging end of a shaft iournalled within a longitudinally adjustable housing:

preloading means comprising a thrust spindle for engaging the overhanging end of the guide disc shaft, a hollow spindle in which the thrust spindle is housed free to float universally between a seat at the outer end of the hollow spindle and the end of the shaft, a longitudinally movable housing in which said hollow spindle is journalled, and means for forcing said housing inward'thereby to force the thrust spindle against the end of the shaft.

9,. In a cross-rolling mill having a pair of helically acting skewed reducing rolls and a rotary guide disc mounted to bear on the workpiece between the reducing rolls, the guide disc being carried by the overhanging end of a shaft journalled within, a longitudinally adjustable housing; preloading means comprising a bearing housing longitudinally movable in alignment with the housing of the guide disc shaft, a hollow spindle journalled within said housing, a thrust spindle within the hollow spindle of a diameter less than the diameter of the bore of the hollow spindle, the inner end of the thrust spindle being spherically curved to engage a correspondingly but oppositely spherically curved seat at the end of the guide disc shaft and being loosely means for forcing said bearing housing inward,

thereby to force the thrust spindle against the end of the shaft.

10. In a cross-rolling mill having a pair of helically acting skewed reducing rolls, a driven shaft extending transversely of the pass'line of the mill, bearing means for said shaft, a guide disc mounted on the inner end of said shaft beyond said bearing means and extending between the reducing rolls to bear on a workpiece being advanced by the rolls, means for moving said 1 bearing means and shaft longitudinally for adjustably positioning the guide disc with relation to the reducing rolls and for moving said bearing means to withdraw the shaft for disc changing,

' and preloading means comprising a thrust spindle mounted in alignment with said shaft for engagement with the overhanging end thereof and for rotation therewith, the shaft-engaging end of said spindle being free to move laterally with the end of the shaft, and means for forcing said thrust spindle against the end of the shaft.

11. Apparatus as claimed in claim 10, in which the overhanging end of'the shaft is provided with a detachably secured end piece against which the thrust spindle bears.

12. In a cross-rolling mill having a pair of helically acting skewed reducing rolls and a pair of rotary gu-ide discs mounted on driven shafts on opposite sides of the reducing rolls to bear on the workpiece between the reducing rolls, preloading means for applying to each ofthe guide disc shafts axially thereof pressure suflicient to (take out clearance in and harmful yields of the shaft mounting parts.

sides of the reducing rolls to bear on the tubular 13. In a cross-rolling mill having a pair of helically acting skewed reducing rolls and a pair ofrotary guide discs mounted on opposite sides of the reducing rolls to bear on the workpiece between the reducing rolls, each guide disc being carried by the overhanging end of a shaft journalled within a longitudinally adjustable ho'using; Dreloading means for each guide disc comprising a thrust member mounted for engagement with the overhanging end of the guide disc shaft, and means for forcing the thrust member against the end of the shaft.

drel and a pair of rotary guide discs mounted on opposite sides of the reducing rolls to bear on the tubular blank between the reducing rolls, the

guide discs being spaced apart to permit the tubular blank to bulge somewhat away from the mandrel and each disc having its rim closely spaced from the reducing roll which rotates the tubular blank toward the disc; preloading means for each guide disc comprising a thrust member mounted for engagement with an end of the guide disc shaft and means for forcing the thrust member against the end of the shaft.

15. In a cross-rolling mill having a pair of helically acting skewed reducing rolls and a rotary guide disc mounted on a driven shaft to bear peripherally on the workpiece between the reducing rolls, prelcading means for applying to the guide disc axiallythereof pressure sufficient to take out clearances in and'harmful yields of the shaft mounting part, and preload'ing means for applying to the reducing rolls transversely of the axes thereof pressure sufficient to take out clearances in and harmful yields of. the roll mounting parts.-

16. In a cross-rolling tube reducing mill having a. pair of helically acting skewed rolls for reducing the wall thickness of a tubular blank on a mandrel, the rolls being mounted with their shafts joumalled in adjustable bearingblocks, and a pair of rotary guide discs mounted on opposite blank between the reducing rolls, the guide discs being spaced apart to permit the tubular .blank to bulge somewhat away from the mandrel and each disc having its rim closely spaced from the reducing roll which rotates the tubular blank toward the disc; preloading means for applying to each of the guide disc shafts axially thereof pressuresuflicient to take out clearances'in and harmful yields of the shaft mounting parts, and preloading means for applying to the reducing rolls transversely of the axes thereof pressure suflicient to tak out clearances in and harmful yields of the roll mounting parts.

17. In a cross-rolling mill having a pair of helically acting skewed reducing rolls each journailed in two spaced adjustable bearing blocks; preloading means for applying to each 'of said bearing blocks at points above and below the pass line and between opposing pairs of bearings pressure transversely of the axes of rotation of the rolls sufiicient to take out clearances in and harmful yieldsof the roll mounting parts.

18. In a cross-rolling mill having a pair of helically acting skewed reducing rolls each journalled in two spaced adjustable bearing blocks; preloading means comprising a plurality of fluid pressure jacks mounted between the bearing blocks at one end of the rolls and a. plurality of fluid pressure jacks mounted between the bearing blocks at the other end of the rolls for applying to the bearing blocks at points above and below the pass line pressure suflicient to take out clearances in. and harmful yields of the roll mounting parts.

19. In across-rolling mill having a pair of helically acting skewed reducing rolls each journalled in two spaced adjustable bearing blocks; preloading means as claimed in claim 18 inwhich the fluid pressure jacks are mounted in openings in water shields mounted to shield the roll bearings.

Sm E. nmscnna.

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