US2241083A - Method of making upset seamless tubing - Google Patents

Description

y 1941- s. 'E. DIESCHER 2,241,083

METHOD OF MAKING UPSET SEAMLESS TUBING Filed Nov. 7, 1938 3 Sheets-Sheet l 3 3 a INVENTOR.

wlmzssss BY 'LZM ,N-IZJ I 9'- ATTORNEYS.

May 6, 1941- s. E. DIESCHE R METHOD OF MAKING UPSET SEAMLESS TUBING Fild Nov. '7, 1938 a Sheets-Sheet 2 INVENTOR. 1

z, ATTORNEYS.

5 Sheets-She t 5 Filed Nov. 7, 193

INVENTOR 1%; ATTORNEYS.

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ww N Q :1 mm. m m\ 2 fimwuwgggag E255 Patented May 6, 1941 METHOD OF MAKING UPSET SEAMLESS TUBING Samuel E. Diescher, Pittsburgh, Pa., assignor to Diesclier Tube Mills, Inc Pittsburgh, corporation of Delawar Pa., a

Application November 1938, Serial No. 239,211

7 Claims;

This invention relates to the manufacture of seamless tubing having one or more portions of it provided with a wall thickness greater than normal, or; in other words, having what is conventionally known as one or more upsets.

is first heated and then subjected in suitable dies to compression in a direction parallel to the axis of the tube to upset or thicken the metaL' This is a hot work operation that is performed subsequent to the production of tubes, and accordingly adds materially to their cost of manufacture. Furthermore, in such operations it is, difflcult, if

not impossible, so to upset the ends of tubes that the transition from the thickened to the normal wall is of a sufficiently gradual slope fully to meet many requirements of service. when conventionally formed upset tubing is subjected to vibration it is liable to break in the region of its transition from its upset to its normal wall thickness by reason of the lnsuilicient slope of wall thickness in such region. Also, the upsets that can readily be formed in the conventional manner just explained are so limited in length that the upset ends of the tubes cannot be repeatedly cut back for rethreading, as is frequently desirable in the repeated use of oil and gas country goods. For longer upsets or upsets made in lighter wall product more than one such upsetting operation is required, and, in the lightest wall product that can be made by hot work- For example,

mandrel which introduces a time consuming additional and costly operation.

The objects of the present invention are to provide a method of manufacturing upset seamless tubing in which the upsets can be made of any desired length, at the ends or in any desired positions throughout the length of the tubing, with any desired slope in the transition from the upsets to the normal wall thickness, and without performing any manufacturing step in additionto those required for the production of tubin having uniform wall thickness from endto end except when the tubing is produced with relati'vely. thick upsets. l

In my United States Patent No. 1,870,209 there is disclosed a method of reducing the wall thickness and elongating a tubular blank, according to which, in the manner therein specifically disclosed, a tubular blank or work piece iscrossing, upsetting by the usual method may be regarded as being commerciallyimpossibie.

While upset tubing is now made in the manner just explained, the prior art contains several 'sug. gestions that upsets be formed in the course of production of tubing, and particularly in the manufacture of seamless tubing by the swaging process. According tothese suggestions, swaging mandrels are provided with portions which are of smaller than normal diameter and on rolled on a cylindrical mandrel of the same cross section throughout its working extent. The helicaliy acting cross-rolls uniformly reduce the wall thickness of the blank and cause it to bulge laterally away from the mandrel between such rolls, and feed the blank and the mandrel forward. Between the cross-rolls the lateral bulging of the blank is limited, the peripheral flow of the metal is diverted longitudinally, and the metal of the blank is pulled forwardly by a pair of guide discs that are driven at a peripheral speed in excess of the speed of longitudinal movement of the blank effected by the cross-rolls.

My present invention is predicated primarily upon my discovery that its stated objects can be attained during the elongating and wall reducing of tubular blanks according to the method of my aforesaid patent by eifecting the cross-rolling on a mandrel which has a normal-diameter cylindrical portion for determining the normal wall thickness of the elongatedtubing, and which has a smaller-diameter portion for producing an upset, or, in other words, a greater than normal wall thickness. 1 have found that by properly which upsets or thickened portions are swaged. 1

Because such tubes are formed in closed passes the'y'stick tightly upon the mandrels. This requires the upsetting to be performed in stages, each preceded by a partialextraction of the coordinating controllable elements and factors of the mill and method disclosed in my aforesaid patentpa seamless tube canbe provided with normal upsets at one or both of its ends and also at any desired intermediate point or points throughout its length without performing any operation in addition to those required for the "production of a like tube of uniform wall thickness from end to end. When itis desired to similarly provide a; tube with one or more relatively thick, as distinguished from normal, upsets an additional procedural stepof a simple the elements of the mill being formed and coordinated to elongate a tubular blank and simultaneously to provide its ends with upsets;

Fig. 2 a central sectional view through a mandrel stripper in the operation of removing a mandrel from a tube after the completion of an elongating operation in which the ends of the tube have simultaneously been provided with normal upsets; Fig. 3 a view similar to Fig. 2 showing the stripper in the operation of removing a mandrel on which a tube has been elongated and simultaneously provided with normal upsets intermediate of its ends; Fig. 4 a vertical longitudinal central view of an apparatus for removing a mandrel from a tube that has been elongated and simultaneously provided with relatively thick end upsets; Fig. 5 a detailed view partly 2,241,oss

I its forward end engages another removable stop in Fig. l, the working elements of the mill having first been suitably adjusted to obtain the desired result as will presently be explained. This in longitudinal central section, of the end of a specially formed mandrel; Fig. 6 a longitudinal Fig. 6; and Fig. 10 a vertical longitudinal central sectional view of a reciprocating expander operating upon the end of a tube initially provided with an interior upset.

In the practice of my invention in its applicability to the elongating of tubular blanks and simultaneously providing them with normal end upsets, it is first necessary to provide suitable mill comprises a pair of oppositely disposed helically acting rolls 6, which may be of general barrel-shape type, as illustrated, although they may be of any other desired type or form such as conical or disc. When barrel-shaped cross rolls are used their axes are inclined to each other and to the line of feed of a blank between them. Disposed between the cross rolls, and on opposite sides of the pass between them, there are surfaces that bear on the blank and move in the direction of its longitudinal extent. These surfaces are preferably the grooved peripheries of a pair of guide discs 'I which are driven at a peripheral speed materially in excess of that of the longitudinal movement of the blank effected by the helically acting cross rolls. In adjusting the mill v the cross rolls are so positioned laterally from the center line of the pass that at the throat, or most distance from the mandrel in excess of the spacmandrels, such as illustrated in Fig. 2. Each such mandrel has a normal-diameter cylindrical portion 2 which cooperates with helically acting re ducing rolls to determine the normal wall thickness of the-resultant tube, and is provided at its front and rear ends with smaller-diameter portions 3 and .4, respectively, which similarly cooperate with suchrolls to produce upsets at the ends of tubes. preferred to have the rear small-diameter portion 4 of greaterlength than the forward portion 3. Between its end and intermediate portions the mandrel is provided with tapered sections 0, the extent of which is determined largely from the slope of transition that is desired from the upsets Although it is not essential, it is to the normal wall thickness of a tube. This special forming of mandrels involves merely a machining. operation that adds little, if any, to the cost of production of the tubes.

A' mandrel such as just described is placed within a thick-wall tubular blank which may be, and preferably" is, produced by piercinga solid billet, although other tubular blanks, may

- be used. Because the extent or the forward end upset of an elongated tube depends upon the length of the forward end of the blank that is reduced between the cross and the smallerdiameter portion 3 of the mandrel, it is desirable definitely to position the end of the mandrel with ing of the cross rolls. In thus positioning the guide discs, due consideration must be given to preserving their functions of diverting longitudinally the peripheral flow of the metal, limiting the bulging of the blank between the cross rolls and away from the mandrel, and pulling the blank forward in the pass.

With the cross rolls and guide discs thus p0sitioned, and with the forward ends of the blank and mandrel relatively positioned in the manner explained above, the blank and mandrel are fed forwardly in the line ofpass of the mill until the front end of the mandrel is in the pass and the front endof the blank is engaged by the cross rolls. The wall thickness of the forward end of the blank is first reduced between the cross rolls and the front smaller-,diameter'portion j of the mandrel to determine the wall thickness of the forward end upset of the'resulting; tube. As the operation proceeds, the cross rolls ,act successively upon the portion of the blank between them and the tapered section 5 to determine the slope of transition from the upset to the normal wall 'thickness, then upon the portion of the blank section I of the mandrel to determine the slope of and moving the mandrel through the blank until transition, and finally'upon the portion of the blank between themand the rear smalldiameter portion A .of the mandrel. to determine the rear end unfit. As shown In Fig. 2, the tube has a forward end upset ll, an intermediate portion H of rior'msl'wall thickness, a rear end upset l2, and sloping transition sections it and which are driven at such peripheral speed that the elongated portion of the tube moves longitudinally at a more rapid rate than does the' mandrel. Accordingly, at the end of a tube forming operation the forward end of the mandrel normally lies within the forward end of the tube, as shown in Fig. 2. This increase of rate of longitudinal movement of the forward end of the tube is effected primarily during the elongation of the normal wall portion of the tube because of the greater reduction in wall thickness then being made, there being less and in some cases no differences, in rate of movements during the formation of the upsets l and [2. Because ofv this and of the ovality created while being rolled there is no binding of therear upset end I2 of the tube upon the mandrel while it is being formed, regardless of the wall thickness of such upset; Should the upset be of normal thickness the ovality created in the rolling thereof will suflice to provide clearance between the bore of practice of my invention in elongating tubular the upset and the body of themandrel and thus avoid any possibility of binding, and should the upset be of heavy thickness there will be so little difference between the forward speed of the mandrel and of the upset portion as to permit what ovality that does occur to suffice for the little forward clearance that may be needed.

An important factor involved in the forming of normal upsets in the practice of this invention is that the relative spacings of the guide discs and of the cross rolls, and the relation between the diameters of the normal-diameter portion 2 and the smaller-diameter end portions 3 and l of the mandrel are such that the interior circumference of the upsets is greater than the circumference of the normal-diameter portion of the mandrel. The result of this coordination of the several elements of the mill is that the mandrel can be freely removed from the formed tube. This may be done in the manner illustrated in Fig. 2 by engagingthe rear end of the mandrel between a pair of yieldingly mounted pinch rolls l5 which are driven to move the mandrel outwardly, and by abutting the end of the tube against a stripping collar l6. This mandrel extractor is used in removing mandrels from tubes having uniform wall thickness from end to end when they are produced according to the method disclosed in my aforesaid Patent No. 1,870,209. Accordingly, in the practice of my present invention seamless tubes having normal end interior upsets are produced without any procedural step in addition to those required in a production'of such tubing having uniformwall thickness from end to end. Reference has been made to the difference in rate of longitudinal movements from the forward end of a tube and a mandrel on which it is formed. This difference in rate is substantially uniform for a given setting and driving of the mill and for a given mandrel size when used to produce end upset tubing from tubular blanks of uniform size. Accordingly, successively formed tubes have their end upsets uniformly spaced' apart.

By way of example, and not of limitation, the following specific data are given to illustrate the construction and positioning of mill elements, including the mandrel, that may be used in the blanks and simultaneously providing them with normal end upsets in the manner explained above. The mandrel may have a normal diameter portion 20 feet 6 inches in length and 2.41 inches in diameter, and have at each end, beyond its 20 feet 6 inches normal diameter portion, a reduced portion of 2.19 inches in diameter, and the tubular pierced blanks may have an outside diameter of 31% inches, a wall thickness of 0.38 of an inch, and may be 14 feet! inches long. With the cross rolls spaced 2.78 inches from each other at the throat of the pass, and the bottoms of the peripheral grooves of the guide discs spaced 3.10 inches from each other at the throat of the pass, the blanks will become elongated to tubes approximately 30 feet long, 3 inches outside diameter from end to end, 0185 of an inch normal wall thickness, and 0.295 of an inch wall thickness at the upset ends. The interior circumference of the end upsets will be greater than the circumference of the normaldiameter portion of the mandrel, so that the resulting tubes can readily be stripped from the mandrel in the manner shown in Fig. 2.

In the practice of the invention, tubes may be provided with one or more interior upsets intermediate of their ends by following the same procedure that has thus far been explained, except for the construction of the mandrel, which, as shown in Fig. 3, is formed to have a plurality of normal-diameter portions 20 at its ends and intermediate thereof, and a plurality of small diameter portions 2| intermediate of its ends.

Tubes elongated on such mandrels have normal successfully used in the practice of my invention in elongating tubular blanks and simultaneously providing them with normal intermediate upsets of the character illustrated in Fig. 3. The mandrel has a normalediameter portion 1.70 inches in diameter, and six smaller-diameter portions 1.56 inches in diameter. The tubular pierced blanks were 103.5 inchesin length having an outside diameter of 2% inches and a wall thickness of 0.295 of an inch. -These blanks were elongated and sized into tubes averaging 14 feet 3 inches in length having an outside diameter of 2.35 inches,'a normal wall thickness of 0.20 of an inch, and internal upsets of 0.27 of an inch. in thickness. In making the upset tubes just described the main or cross rolls were spaced 2.10 inches and the guide discs 2.37 inches apart.

Tubes having upsets intermediate of their ends may advantageously be used in the manufacture of upset tubular articles in multiples, wherein the upsets are located at points where greater strength is required. Such tubes may be provided with an upset at one or both of their ends,.

and, in the production of tubes having no intermediate upsets, upsets may be formed at only one of their ends if desired.

By way of further example and not of limitation, the following specific data are given toillustrate the construction and positioning of mill elements, including the mandrel, that have been used in the practice of my invention in elongating tubular blanks and simultaneously providing them with very long end upsets as well as very long intermediate upsets. The mandrel had a normal diameter of 1.590 inches. It was turned down to 1.470 inches at the ends, as well as at two stations therebetween, in a manner as to provide three portions of the mandrel, each 24 /2 inches long, of normal diameter, and intermediate of these to provide two portions, each 22 inches long of reduced diameter, namely 1.470 inches. The intermediate tapers 'were 1.00 inch long. On this mandrel tubes 2 inches in diameter and 16 feet 1 inch long were rolled, having 0.240 inch of wall at 20 inches of length at their two end upsets and also at 27 inches of length at their two intermediate upsets. The three remaining portions, intermediate of the upsets, were each 33 inches long and were of0.l87 inch, or of normal wall thickness except at the transition tapers. These articles were rolled with the same ease as would have been the case were the mandrel of uniform diameter and the product of uniform wall thickness. In this case the main rolls were spaced 1.964 inches apart and the guide discs were 2.25 inches apart. The pierced shells used were 2.50 inches in diameter, 0.325 inch in wall thickness and 105 inches long.

The invention has been thus far explained in its applicability to the production of tubing having end and intermediate upsets of ,a normal character, as distinguished from relatively thick upset which are sometimes required. In the practice of my invention one or both ends of tubes maybe provided with relatively thick upsets with no change in the elongating procedure except that the smaller-diameter end portions of the mandrels are, with the relation to their normal-diameter portions, reduced more in size than in mandrels used for producing normal upsets. One difierence between an elongated tube provided at both ends with relatively thick rather than normal upsets is that in the former the interior circumferences of the upsets are smaller than the normal-diameter portion of the mandrels, as a result of which the mandrel on which each tube is formed is entrapped by the upsets. Another difference is that the outside diameter of relatively thick upset ends is slightly less than that of the normal wall thickness portion of the tube. This second difference arises from the fact that in the production of relatively thick end upsets the relatively small reduction in wall thickness of the portions of the tubular blank that form the upsets does not cause the metal to bulge laterally or oval against the guide discs to an extent sufficient to expand the circumference of the upsets to that of the normal wall thickness portion of the blank which is given a materially greater reduction by the cross rolls.

To remove a thus entrapped mandrel from a tube that has been provided with relatively thick and upsets, it is preferable to use a pusher mechanism, such as illustrated in Fig. 4, than the pinch rolls of Figs. 2 and 3, because a greater and more positive force can be applied by the pusher mechanism. As shown in Fig. 4, the pusher comprises a ram 25 attached to a crosshead 26 which is connected to the end of a piston rod 21 adapted to be reciprocated by a compressed air or other form of pressure fluid cylinder 28. In removing a mandrel by t s pusher, the forward end of ram 25 may be centered in 2,241,,ces

the trailing end of the mandrel which projects from a finished tube, and the fluid pressure cylinder actuated to push the mandrel out of the tube, the end of which is engaged by a stripping collar 29. During this operation the upset at the end of. the tube, which at this stage is still .hot and readily deformable and which abuts against collar 29, is expanded by the tapered section of the mandrel between its normal. and smaller-diameter portions. This leaves the outside diameters of the upsets of diflerent size, the upset through which the mandrel has been removed being larger than that at the other end of the tube. However, this difference in the outside diameters of the upsets, and the difierence, explained above, between the outside diameters of the upsets and normal wall portion of the tube, are not prejudicial because the tube may readily be brought to uniform diameter from end to end by passing it through sizing rolls or a sink mill as is customarily done subsequent to the production of tubes having uniform wall thickness throughout.

If at the completion of the mandrel-removing operation it is desired to have both of the end upsets of the same diameter, the pusher may be given a short stroke suflicient only to cause the mandrel to expand one upset, and the tube and its contained mandrel may thenbe transferred laterally to position it in line with a second similar pusher mechanism constructed to engage the other end of the mandrel and push it through the previously unexpanded upset and entirely out of the tube. If desired, the tube may then be passed through a sizing or sink mill as explained above, or its upset ends may be further expanded in a manner hereinafter described, or it may be treated in any other desired way.

To resist wear on the tapered sections of a mandrel while it is moved in the manner just explained to expand relatively thick upsets in the removal of the mandrel from tubes, such sections may, as shown in Fig. 5, be provided with heat and wear-resisting collars 30. When thus, formed, the normal-diameter portion of the mandrel may consist of a cylindrical rod 3|, and each smaller-diameter end portion may consist of a short rod 32 provided with an offset 33 to receive a collar 3%) and with a threaded end 34 adapted to be screwed into the end of rod 3|.

Althoughthe production of tubes having relatively thick upsets requires a manufacturing step or steps inaddition to those required for the production of tubing having uniform wall thickness from end to end, nevertheless no loss of operating time occurs because the additional step or steps are performed immediately after the elongating of each upset tube and in less time than required for the elongation.

In providing tubes with upsets according to this invention, all the upsets are initially of the interior type, by which is meant that the increased wall thickness of the upsets contracts the bore of the normal wall thickness portion of the tube. However, the interior upset ends of the tube can readily be converted into exterior upsets by merely expanding the ends, whether the upsets are of the normal or the relatively thick type. While in some cases this may b done on the original heat of the metal, to prevent the metal from becoming too cool to be readily expanded without impairing it, the tubes may, in their passage from the mandrel extractor to the expander, be passed through a heating furnace.

Both upset ends of a tube may be simultaneously expanded by a rotary expander such as length of the'tube will be seamless tubes duringtheir regular course of illustrated in Fig. 6. To do this the ends of a heated tube. and their intermediate portions as far as may be necessary, are engaged by clamps 40 which hold them in alignment'with spinning heads 4|, each of which is attached to or is formed on the end of a spindle 42 adapted to be rotated'by a motor 43. As shown particularly in Figs. 8 and 9, spinning head M has a frustrum-like portion 44 which effects the expanding of an upset and a cylindrical portion 45 which removes any scores that may occur during such expanding. Spindle 42 is provided centrally with a bore 46 which is closed at its outer end and through which, and radial spindle ports 41, steam or a combustible gas or lubricant is led to the face of the spindle to facilitate the spinning or expanding operation and to cool thespinning tool and also to remove scale that may accumulate at the tool. The spinning tool and its driving motor are mounted upon a table 50.

which is slidably supported on a platen and is engaged by a feed screw 52 rotatably mounted on the platen and adapted to be driven by a motor 53 through a worm shaft 54 and a worm gear 55. The platen 5| is slidably mounted upon a table 56 to properly position the spinning tool for operation upon tubes of different lengths. As the spinning head 4| is rotated by the motor 43, screw 52 is driven by motor 53 to feed the head through the upset end of the tube until the entire upset, including the adjoining transition portion of the tube, is so expanded that its inside diameter is the same'as that of the main or normal wall portion of the tube.

In Fig. 10 there is illustrated an alternative form of expanding apparatus in which a nonrotatable expanding tool 60 is attached to the end of a spindle 6| adapted to be reciprocated by a compressed air or other form of fluid pressure cylinder 52. In Fig. '7 there is shown a tube 65 provided with an end exterior upset 65 which may be either of the normal or relatively thick type, the upset having been thrown to the exterior of the tube by expanding an interior upset in the manner explained with reference to Figs. 6 and 10. r i

A specificexample of tubes requiring exterior end upsets is oil country pump tubing having a 2-inch nominal inside diameter from end to end, a normal wall thickness of 0.19 of an inch, and

an upset end wall thickness of 0.30 of an inch,

and being 2% inches in outside diameter. Such a-tube may be formed from that produced in the first of the above explained examples, the tube when elongated bein'gappro'ximately feet in length and 3 inches in outside diameter, and being provided with normal interior upsets at its ends. After being elongated the tube may be passed through a sink mill to reduce its outside diameter to that required, namely 2% inches. In its passage through the sink mill the increased in excess of 33 feet, and its wall thickness will be increased somewhat throughout but especially at its ends, resulting in a tube having a normal wall thickness of 0.19.0f an inch, an upset end wall thickness of 0.30 of an inch, and an interior diameter of 2 inches throughout its normal wall portion. The upset ends of the tube may then be expanded in the manner explained with reference to either Fig. 6 or 10 to produce the required exterior upsets.

Many of the advantages of my invention are apparentfrom its foregoing description. In the first place, by its practice upsetsare-formed on manufacture, rather than subsequent thereto, and they are iormed without any procedural step in addition tothose. used in the production of seamless tubes having uniform wall thickness from end to end. The result of this is a very substantialsaving in thecost of manufacture of upset tubing; In all cases the upsets may be of any desired length and the slopes of transition in wall thickness of the tube from their upsets to their normal thickness walls may be as gradual as desired for any purpose. Thus the upset ends of tubes may be cutback for rethreading, as is frequently done particularly in oil country tubing, and the resistance of .the tubes to breakage-in their transition sections is greatly increased. Moreover, as the entire procedure involved in the production of upset tubing may be carried out rapidly enough to maintain the entire tube at working temperature during its deformative period, the subsequent cooling of the tube occurs uniformly and as a consequence the tube assumes a normalized condition.

A further advantage of the invention as compared to prior art suggestions that upsets be formed in the course of production of tubing is that the tubes are formed in open passes, by which is meant that they are formed in passes which free the tubes from rather than cause them to be formed tightly uponthe mandrels. The result of this is that additional steps are not required to free the formed tubes from the mandrels.

A still further advantage of my invention is that it may be practiced in the production of very thin wall tubing which in its finished form is not provided with upsets. In the hot production of the very thin wall tubing that can be made according to the method disclosed in my aforesaid Patent No. 1,870,209, as, for example, of an inch in wall thickness, the trailing ends of the tubes sometimes become slightly torn and injure the highly finished surfaces of the guide discs, necessitating the substitution of new discs and the refinishing of thosewhose peripheral faces have been thus marred. By providing the ends of such thin wall tubing with relatively it. However, I desire to'have it understood that.

within the scope of the appended claims, the invention maybe practicedotherwise than specifically disclosed. a I claim:

1. The method ofelongating a heated tubular blank and simultaneously reducing its wall principally to a normal and;locally to an upset thickness, which comprises cross-rolling the blank continuously from end to end between helically acting reducing rolls and can longitudinally moving mandrel having a normal-diameter cylindrical portion cooperating'withthe reducingr olls for determining said normal wall thickness and having a smaller-diameter portion for producing said upset wall thickness, and determining theouterdiameter ofthe formed tube by. surfaces bearing on the blank and moving in the direction of its longitudinal movement.

2. The method of elongating a heated tubular blank and simultaneously reducing its Wall principally to a normal and locally to an upset thickness, which comprises cross-rolling the blank continuously from end to end between helically acting reducing rolls and on a longitudinally moving mandrel having a normal-diameter cylindrbcal portion cooperating with the reducing rolls for determining said normal wall thickness and having a smaller diameter portion cooperating with the reducing rolls for determining said upset wall thickness, and determining the outer diameter of the formed tube by surfaces bearing on the blank and moving in the direction of the longitudinal movement of the blank at a speed greater than the longitudinal movement of the blank.

3. The method of elongating a heated tubular blank and simultaneously reducing its wall at its ends to an upset thickness and throughout its intermediate portion to a normal smaller thickness, which comprises cross-rolling the blank continuously from end to end between helically acting reducing rolls and on a longitudinally moving mandrel having an intermediate normaldiameter cylindrical portion cooperating with the reducing rolls for determining said normal wall thickness and having smaller diameter end portions for producing said end upset wall thickness, and determiningthe outer diameter of the formed tube by surfaces bearing on the blank and moving in the direction of its longitudinal movement.

- 4. The method of elongating a heated tubular blank and simultaneously reducing its wall principally to a normal and locally to an internal upset thickness, which comprises cross-rolling the blank continuously from end to end on a mandrel moving longitudinally between helically acting reducing rolls and between rotating guide discs, the mandrel having a normal-diameter cylindrical portion for determining said normal wall thickness and having a smaller diameter portion for determining said upset wall thickness, causing the cross-rolls to compress the blank between them and the mandrel at both its normal and smaller diameter portions and to so expand the blank from the mandrel and against the guide discs that the interior circumference of the inwardly upset portion of the blank is greater than the exterior circumference of the normal diameter portion of the mandrel, and causing the guide discs to pull the blank forwardly, whereby the upset thickened wall portion of the blank may freely pass over the normal diameter portion of the mandrel.

5. The method of elongating a heated tubular blank and simultaneously reducing its wall at its ends to an upset thickness and throughout its intermediate portion to a normal smaller thickness, which comprises cross-rolling the blank continuously from end to end on a mandrel moving longitudinally between helically acting reducing rolls and between rotating guide discs, the mandrel having an intermediate normal-diameter cylindrical portion for determining said normal wall thickness and having smaller diameter end portions for determining said end upset wall thickness, causing the cross-rolls to compress the blank between them and the mandrel at both its end and intermediate portions and to so expand the blank from the mandrel and against the guide discs that the interior circumference of the inwardly upset end portions of the blank is greater than the exterior circumference of the normal diameter intermediate portion of the mandrel, and causing the guide discs to pull the blank forwardly, whereby the 'upset end portions of the blank may freely pass over the intermediate portion of the mandrel.

6. The method'of elongating a heated tubular blank and simultaneously reducing its wall at its ends to an inwardly upset thickness and throughout its intermediate portion to a normal smaller thickness, which comprises cross-rolling the blank continuously from end to end on a mandrel moving longitudinally between helically acting reducing rolls and between rotating guide discs, the mandrel having an intermediate normal diameter portion for determining said normal wall thickness and having smaller diameter end portions for determining said end upset wall thickness, causing the cross-rolls to compress the blank between them and the mandrel at both its end and intermediate portions and to so expand the blank from the mandrel and against the guide discs that the interior circumference of the inwardly upset end portions of the blank is less than the exterior circumference of the normal diameter intermediate portion of the mandrel, causing the guide discs to pull the blank forwardly, and thereafter expanding the inwardly upset ends of the formed tube.

7. The method of elongating a heated tubular blank and simultaneously reducing its wall principally to a normal and at an end to an internal upset thickness, which comprises cross-rolling the blank on a mandrel moving longitudinally between helically acting reducing rolls and between rotating guide discs, the mandrel having a normal-diameter cylindrical portion for determining said normal wall thickness and having a smaller diameter end portion for determining said upset wall thickness, causing the cross-rolls to compress the blank between them and the mandrel at both its normal and smaller diameter portions and to so expand the blank from the mandrel and against the guide discs that the interior circumference of the inwardlyupset portion of the blank is smaller than the exterior circumference of the normal diameter portion of the mandrel,

and thereafter expanding the inwardly upset portion of the formed tube by moving the normal diameter portion of the mandrel into such upset portion.

SAMUEL E. DIESCHER.

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