US3154848A

US3154848A - Apparatus and method for forming close tolerance tubing

Info

Publication number: US3154848A
Application number: US84744A
Authority: US
Inventors: Vernon R Powell
Original assignee: EASTWOOD ACCEPTANCE CORP
Current assignee: EASTWOOD ACCEPTANCE CORP
Priority date: 1961-01-17
Filing date: 1961-01-17
Publication date: 1964-11-03
Anticipated expiration: 1981-11-03

Description

V. R. POWELL Nov. 3, 1964 5 Sheets-Sheet 1 Filed Jan. 17, 1961 INVENTOR.

I/EPNO/v R. .RDWELQ ATTORN EY Nov. 3, 1964 v. R. POWELL 3,154,843

APPARATUS AND METHOD FOR FORMING CLOSE TOLERANCE TUBING Filed Jan. 17, 1961 S Sheets-Sheet 2 1 m I'ILI I III I v '1' I m r DELIILL w o o 0 5 o gl 0 o o 0 ill u m l i IN VENTOR. lfisg/vozv R. EbwELL eBMQW ATTORNEY Nov. 3, 1964 v. R. POWELL 3,154,348

APPARATUS AND METHOD FOR FORMING CLOSE TOLERANCE TUBING Filed Jan. 17, 1961 5 Sheets-Sheet 3 INVENTOR. ERNONR-RWELL.

ATTORNEY Nov. 3, 1964 v. R. PQWELL 3,154,348

APPARATUS AND METHOD FOR FORMING CLOSE TOLERANCE TUBING Filed Jan. 17, 1961 5 Sheets-Sheet 4 ATTO'RN EY v. R. POWELL 3,154,848

APPARATUS AND METHOD FOR FORMING CLOSE TOLERANCE TUBING Nov. 3, 1964 5 Sheets-Sheet 5 Filed Jan. 17, 1961 1 owm Nmm hm mum 1 mm wnm n Nun \wm *wh United States Patent 3,154,348 APPARATUS AND METHQD F93 FQRMENG CLGSE TGLERANQE TUBING Vernon R. Powell, Long Beach, Calif., assignor to Eastwood Acceptance Corp Los Angeies, sCalif. Filed Jan. 17, 1961, Ser. No. 84,744- 26 Claims. (0. 29516) The present invention relates generally to the working of metal, and more particularly to a method and apparatus for transforming stock tubing of a work-hardenable metal to close tolerance tubing having improved physical qualities, as well as tubing formed by said method.

The present application is a continuation-in-part application of my application entitled Metal Working Process and Articles of Manufacture Formed Thereby, filed in the Patent Office on March 7, 1960, under Serial No. 13,238. Application Serial No. 13,238 is in turn a continuation-in-part application of my application entitled Method for Forming Close Tolerance Tubing and Articles Thereon filed May 31, 1955 under Serial No. 512,- 061 which issued as Patent No. 2,927,372 on March 8, 1960.

Prior to a detailed discussion of the present invention, the following brief review of known information on the formation of tubing and cold-working of metal and alloys thereof is submitted. The term cold-working is used in the present application to denote the working of metals and alloys within a temperature range at which they work or strain-harden when subjected to deforming forces which stress the metals or alloys above their elastic limits.

When a work hardenable metal or alloy is stressed beyond its elastic limit, the yield point and yield strength of the metal or alloy is increased in the direction in which the stress is applied thereto. However, the compressive strength of the metal or alloy is not increased. Thus, if a cold-drawn tube is subjected to substantial compressive forces'it may buckle, for if the compressive yield strength is low, plastic deformation will start on the compression side of the tube when the compression yield strength is exceeded, although the stress on the tension side of the tube is still Within the elastic range.

A further disadvantage of work-hardened metal is that While its ductility and resistance to impact decrease in the direction in which the deforming stress is applied thereto, a far greater decrease in ductility and resistance to impact occurs in a direction transverse to the direction of the deforming forces. Thus, a tube formed by longitudinal deformation of the metal defining same would be brittle in a transverse direction relative there-to, and would in all probability fail if used in an environment where it is subjected to substantial torsional forces.

A major object of the present invention is to provide a method and apparatus that may be used to transform stock tubing to close tolerance tubing and concurrently improve the physical qualities of the metal or alloy defining same by the cold-working thereof, with the close tolerance tubing so formed having an improved yield point, tensional strength and compressive strength in both longitudinal and transverse directions relative thereto.

Another object of the invention is to provide a method and apparatus capable of being used in carrying out the present method that permits the production of close tolerance tubing having walls of extreme thinness, production of such close tolerance tubing from a metal such as zirconium that normally galls when extruded or drawn on a draw bench, production of close tolerance tubing without raising the temperature of the stock tubing to the extent that it will oxidize or otherwise be detrimental- 'ice ly affected, and the production of close tolerance tubing which is fre of high residual stresses.

A further object of the invention is to supply a method and apparatus particularly adapted for use in carrying out the method by which stock tubing is transformed to close tolerance tubing that not only has improved physical qualities, but with these improved qualities being uniform throughout the metal or alloy defining the thin- Walled tubing.

A still further object of the invention is to furnish an apparatus that can be used in carrying out the present method by which the stock tubing is transformed to close tolerance tubing by being physically worked in a stress range Within which the metal or alloy defining same plastically deforms, with the working of the stock tubing being accomplished by a combination of longitudinal, compressive and torque-imparting stresses each of a lesser magnitude than that required to permanently deform the metal or alloy of said stock tubing to a substantial degree, with the permanent deformation of the metal or alloy being carried out in a plurality of circumferentially spaced zones that are concurrently rotated about the eX- terior surrace of the stock tubing as well as advanced longitudinally relative thereto.

Yet another object of the invention is to also provide both an apparatus and method of using the same by means of which relatively short lengths or" heavy-Walled stock tubing can be economically transformed to close tolerance tubing of a desired thinner wall thickness and of a substantially greater length, which transformed close tolerance tubing may be either used in that condition, or used as feed stock for the apparatus shown and described in my Patent No. 2,927,372. The transformed close tolerance tubing resulting rom the practice of the present invention is further reduced in wall thickness and increased in length when subjected to the methods described and claimed in Patent No. 2,927,372.

Another object of the present inven ion is to provide a method of transforming stock tubing of a work hardenable metal or alloy to close tolerance tubing of reduced wall thickness, which is strengthened longitudinally and transversely at a desired ratio whereby the transformed tubing is capable of being tailored to the particular o erational environment in which it will b used.

Still a further object of the invention is to provide a method of producing close tolerance, multiply tubing in which two or more separate tubes are physically bonded together Without recourse to the application of heat thereto, with this multiply tubing in its simplest form including an inner tube that may be formed from either a metallic or non-metallic material or a combination thereof which has certain desired physical properties and need not be work-hardenable, as well as an outer tube of a workhardeuable metal or alloy having difierent physical characteristics than that or" the inner tube which is plastically deformed to remain in permanent pressure contact with the inner tube.

Yet another object of the invention is to provide a method of producing close tolerance tubing of multiply construction in which a first tube of a metal haying desired physical properties as to temperature, for instance, is clad both internally and externally by second and third tubes of different materials that are corrosion resistant to the particular environment in which the multiply structure is to be used, which multiply structure is likewise adapted to be formed without brazing, welding, or other processes that would detrimentally affect the various materials defining the first, second and third tubes.

A still further object of the invention is to provide a method that permits the economical fabrication of multiply structures which may be used as pressure vessels, high pressure piping, and heat exchangers.

Yet a further object of the invention is to provide a method and apparatus that can be used in carrying out the method by which the exterior surface of an elongate rigid body, tubular or solid, of either circular or noncircular transverse cross section, can be enveloped in a film of a work-hardenable metal or alloy having desired physical characteristics as to corrosion resistance, resistance to temperature, abrasive action, and the like.

Another object of the invention is to provide a method and apparatus that can be used in carrying out said method in transforming stock tubing to tubing of a thinner wall thickness, the interior surface of which is extremely smooth and can be used for pump barrels, bearings, and the like.

These and other objects and advantages of the invention will become apparent from the following description of a preferred form thereof, and from the accompanying drawings illustrating that form in which:

FIGURE 1 is a side elevational view of an apparatus that may be used in carrying out the process described herein;

FIGURE 2 is a top plan view of the apparatus shown in FIGURE 1;

FIGURE 3 is a fragmentary combined vertical crosssectional and side elevational view of a portion of the apparatus taken on line 33 of FIGURE 2;

FIGURE 4 is a combined end elevational and vertical cross-sectional view of the apparatus taken on line 44 of FIGURE 3;

FIGURE 5 is a combined vertical cross-sectional and elevational view of a portion of the apparatus taken on line 5-5 of FIGURE 3;

FIGURE 6 is a combined vertical cross-sectional and elevational view of a portion of the apparatus taken on line 6-6 of FIGURE 2;

FIGURE 7 illustrates a first means for removably clamping an end portion of stock tubing that is to be transformed to close tolerance tubing to the free end of a mandrel;

FIGURE 8 is an end elevational view of the first clamping means shown in FIGURE 7, taken on line 88 thereof; 7

FIGURE 9 is a longitudinal cross-sectional view of a second clamping means for removably afiixing an end portion of stock tubing to be deformed to close tolerance tubing to the free end of a mandrel;

FIGURE 10 is an end elevational view of the second clamping means shown in FIGURE 9 taken on line Iii-1t thereof;

FIGURE 11 is a vertical longitudinally extending cross sectional view of a third means for removably clamping an end of stock tubing that is to be transformed to close tolerance tubing to the free end of a mandrel;

FIGURE 12 is an end elevational view of the third means shown in FIGURE 11 taken on line 1212 thereof;

FIGURE 13 illustrates a fourth means of removably clamping an end portion of stock tubing to be transformed to close tolerance tubing to the free end of a mandrel;

FIGURE 14 is a transverse cross-sectional view of a fifth means for closing the open end of a length of stock tubing to permit a mandrel to'exert a longitudinally directed force thereon;

FIGURE 15 shows a sixth means for removably closing the open end of a length 'of stock tubing that is to be transformed to close tolerance tubing to permit a longitudinally extending force to be exerted on the stock tubing;

FIGURE 16 is a vertical cross-sectional view of a seventh means for removably closing the open end of a length of stock tubing that is to be transformed to close tolerance tubing to permit a longitudinally extending force to be exerted thereon;

. FIGURE 17 is a fragmentary side-elevational view of a portion of stock tubing being transformed to close tolerance tubing with the rolls D moving to the right as may be seen in FIGURES l and 2;

FIGURE 18 is a transverse cross-sectional view of the tubing, mandrel, and rolls, taken on line 1818 of FIG- URE 17;

FIGURE 19 is a diagrammatic view of the hydraulic system used with the invention;

FIGURE 20 is a fragmentary side elevational view of a portion of stock tubing being transformed to thinner walled tubing which envelops a tubular member; and

FIGURE 21 is a fragmentary side elevational view of a portion of a second length of stock tubing being transformed to thinner walled tubing which envelopes a first length of tubing to provide multi-ply tubing.

Prior to a detailed discussion of the present invention, the method by which a length of stock tubing A formed of a work-hardenable metal is transformed to close tolerance tubing of a thinner wall thickness and improved physical properties is summarized as follows.

With reference to FIGURE 17, a section of a side wall of stock tubing A is shown in which an elongate rigid mandrel B is slidably inserted. In exterior transverse cross-section, mandrel B is slightly smaller than the interior transverse cross-section of tubing A after it has been transformed to close tolerance tubing. By means to be hereinafter explained, one .end of tubing A is anchored in a fixed position, with the other end thereof being removably affixed to the outermost end of the mandrel B by such means as shown in FIGURES 7 to 13 inclusive.

The process of transforming stock tubing to close tolerance tubing of a thinner wall thickness as herein described may be carried out with a number of variations, but irrespective of the variation used, the stock tubing is, during the transforming process subject to one or more forces of sufiicient magnitude to cause the controlled permanent deformation thereof by cold working.

One convenient method of carrying out the process is to subject the mandrel B and the stock tubing A to a rotational force F-S that is just sufiicient to cause permanent deformation of tubing A. After application of force F5, a longitudinally directed force F-l is applied to tubing A to tension the same and cause permanent elongation thereof. Transformation of stock tubing A to close tolerance tubing is completed by the application of forces F-2, F4; and F4 as will hereinafter be described in detail. The advantage of applying the forces F-S and F1 in this manner is that the forces F-l and F-5 of the same magnitude can be sequentially applied to a number of lengths of tubing A' as they are transformed to closed tolerance tubing. However, it must be realized that the transformation process can also be carried out by subjecting the stock tubing A to forces F-l and F-S that are not of a magnitude to cause permanent deformation thereof, but by the application of forces F-Z, F-3 and F- -i later to be described, with the stressing of the tubing A being increased to a degree that it is permanently deformed, cold-worked, and transformed to close tolerance tubing.

Mandrel B is then moved to cause a longitudinal force F1 to be exerted on stock tubing A whereby the tubing A is elongated and also reduced in transverse cross section. Concurrently, a rotational force F-S is preferably applied to mandrel B, with the combined magnitudes of forces F4 and F-S being just sufficient to cause permanent deformation of tubing A. The magnitude of each of the forces F-l and F-S may vary for each transforming operation, and are determined not only by the characteristics of the metal or alloy defining the stock tubing A, but by the transverse cross section thereof as well. How ever, from experience it has been found that satisfactory, if not optimum results, can be obtained if force F-l provides 50% of the deforming force, and F5 the other 50%.

The position of the external surface C of tubing A relative to mandrel B prior to application of forces F-l and F-5 to tubing A is indicated in phantom line in FIG- URES l7 and 18. After "olication of forces F1 and F-' to tubing A, the position of the external surface C is shown in solid line in the same figure and identified by the notation C-l.

A number of hard, barrel-shaped rolls D are provided that are rotatably supported on parallel shafts E, which shafts are in circumferentially spaced relationship and adjacently disposed to the exterior surface Cl of tubing A. Each shaft E is adapted to sustain a radially directed force F-Z exerted thereon, which force is sufficient to press one of the rolls B into the tubing A until the lower exterior surface of the roll occupies me position indicated by the notation C2 in FZGURE 17. Rolls B may then be rotated concurrently about tubing A, and each roll is rotated by a force F-4 which is applied thereto in the direction shown by the arrow in FIGURE 18. As each roll D rotates, it is concurrenty moved longitudinally relative to tubing A. When rolls D move from left to right on the apparatus as shown in FIGURES l and 2, the force F3 is opposite to force F-l, but forces F-3 and F1 are applied to tubing A in the same direction when the rolls R move from right to left on the apparatus as shown in FIGURES 1 and 2.

Three equally spaced rolls D are shown in FIGURE 18. As each roll rotates about tubing A, it advances from the position shown in solid line to that shown in phantom line in the same figure, for each 120 of rotation about tubing A. When forces F-Z, P-3 and F-d are combined they cooperate with forces 5- and F5 to cause plastic deformation of the metal or alloy defining tubing A. As the tubing A being transformed is already stressed to the yield at the time the forces 1 -2, 35-3 and F4 are applied thereto, these combined forces be but a small fraction of the combined forces 5-1 and F5.

For convenience of discussion herein, rolls D are identified as D-l, D2 and D45 (FIGURE 18). V /"nen roll D-l rotates from its initial position as shown to that previously occupied by roll D-Z, an arcuate segment U extending over 12 of the exterior surface of tubing A is compressed and permanently deformed whereby an external surface is formed therein defined by the line identified by the notation C-Z. Also, three circumferentially spaced zones V formed ahead of the rollers D-l, D-2 and 13-3 are subjected to the force 2 -3, as well as longitudinally directed components of the forces P-2 and F l, and all of the forces Fl and F5. The metal or alloy zones V are under maximum stress, and tend to plastically deform with concurrent elongation of tubing A and reduction in the wall thickness thereof to the extent that the exterior surface of the tubing occupies the position identified by the notation (3-2. It will be particularly noted that a portion of he force P 2 is radially directed, and tends to compress the metal or alloy defining the stock tubing A as the rolls D rotate thereabout. Force F-Z on each roll D-l, D2 and D-S is of such magnitude as to force the metal defining each zone V into pressure contact with mandr l E, and the interior surface of the transformed tubing has the same finish as the external surface of the mandrel. During the time that the forces F-l, F-Z, F-3 and F are applied to tubhzg A, the mandrel B and tubing A are concurrently rotated by force F-S in the same direction as rolls D, as shown in FZGURE 18.

e forces F-l and 5-3 and portions of forces I and r primarily cause longitudinal stressing of the metal or alloy defining tubing A. is desirable, for improvement in the tensile yield point of a work-hardenable metal is within limits directly related to the degree of deformation, and in the direction in which the stress is applied. However, the ductility of the metal or alloy and its impact resistance in a direction transverse to the direction of the applied force is greatly lessened. The crystallite structure of the close tolerance tubing resulting from the above described process is not only stressed longitudinally, but circumferentially as well. Circumfcrential stressing of the crystallite structure is effected by components of the forces F2, F3 and F-d which augment the force F5.

In rotating the stock tubing A during the transformation thereof to close tolerance tubing, the force F-S causes the longitudinally stressed crystallites of the metal to as some a helical configuration. The tightness of this crystallite helical configuration in the metal of the transformed tubing A will, of course, be dependent on the number of revolutions the force F-S causes the tubing to make during the transforming operation. Stressing of the metal of the stock tubing A by the application of the rotative force F-S thereto, not only improves its physical characteristics as to hoop strength and its capability to Withstand internal pressure, but by reorienting the stressed crystallites in the metal or alloy so that the direction of maximum deformation is not parallel to the longitudinal axis of the transformed tubing, the ductility and impact resistance of the transformed tubing is increased in a transverse direction. Also, the transformed tubing A developed in accordance with the present process is less inclined to buckle under pressive loading. Due to the orientation of the longitudinally stressed crystallites from positions parallel to the longitudinal axis of the tubing by force F-S, there is less likelihood that the compressive strength of a side portion of tubing A will be exceeded while an opposite side portion thereof is under tension, which remains within the elastic range.

A further advantage of the process described hereinabove is that it is a gradual deforming operation in which zones V are sequentially deformed to transform the stock tubing A to close tolerance tubing A. Due to the time taken in plastically forming the tubing to the desired shape, the stressed crystallites have an opportunity to come into equilibrium, with a minimum of internal stresses being left in the transformed tubing. This attainment of equilibrium is believed to be substantially completed during the time the crystallites are in the zones V where they are subjected to longitudinal tensioning, compression, and transverse, circumfcrentially directed forces, all tending to cause such equilibrium with a minimum of residual stresses.

With further reference to the drawings for the general arrangement of the apparatus which is adapted for use in carrying out the transformation of stock tubing A to close tolerance tubing A as previously described, it will be seen in FIGURES l and 2 to include an elongate supporting framework G. if desired, the framework G can be fabricated from a number of sections that are rigidly joined in end-to-end longitudinal alignment by means not shown. However, for the sake of convenience just two sections 6-1 and G2, as shown in FIGURE 1, are described herein. The framework section G-l (FIGURE 2) supports two horizontal, parallel, laterally separated rails It Rails 1% in turn serve to slidably support a carriage H for slidable and longitudinal movement thereon.

Carriage H, to be described in detail hereinafter, supports a power-driven ring-shaped member I that is transversely positioned relative to rails lb and situated thereabove. l /lember J in turn rotatably supports the rolls D41, D-2 and D-3 shown in

FlGURES

17 and 18, which rolls are supported a radially adjustable manner Within the confines of the ring-shaped nember 3. Actually, the member I may be a heavy-duty lathe chuck of a type including three radially movable jaws that are radially and concurrently adjustable. The jaws (not shown) are removed from the chuck and replaced by pairs of laterally spaced legs T12 that support the ends of the shafts E (FIG- URES l7 and l8). Rolls D-l, D2 and D-3 are rotatably mounted on the shafts E, and by use of the modified chuck above described, these rolls can be concurrently and radially adjusted to exert a desired pressure on the exterior surface of tubing A, as shown in FIGURE 18.

A passageway 14 extends longitudinally through carriage H and is of such transverse cross section as to permit longitudinal slidable movement of the stock tubing A being transformed therethrough. Carriage H is preferably moved hydraulically along rails 10, which mode of movement allows a desired force F-3 to be exerted by rolls D on tubing A during the transforming operation.

A second carriage K is provided that is longitudinally movable on the right-hand portion of framework G as shown in FIGURES l and 2. Carriage K includes a power-driven shaft L which is in coaxial alignment with the center of rotation of member I. A jaw mechanism Q is mounted on a support Q-l that is affixed to frame G, which mechanism is capable of gripping one end of the tubing A that is to be transformed and rigidly gripping it during the transforming operation. From experience it has been found that the jaw mechanisms described and claimed in my copending patent applications entitled Tube Gripping Mechanism filed March 7, 1960, under Serial Nos. 13,120, now Patent No. 2,985,455, and 13,127, now Patent No. 3,050,602, are well suited for use as the jaw mechanism Q.

Mechanism Q includes a semi-circular first jaw R and a second jaw M that is pivotally movable relative thereto, with this second jaw being adapted to be opened and closed by activation of a hydraulic cylinder N. A catch T actuated by a hydraulic cylinder T serves to lock jaw M in a closed position to cause the end portion of stock tubing A to be rigidly gripped therebetween. If an end portion of tubing A is to be gripped by jaw mechanism Q, the end to be so gripped is first flared to conform to tapered surfaces formed on the first and second jaws R and M respectively.

The framework G, as can best be seen in FIGURES l and 6, includes a base 23 that may be adjusted into a horizontal position by a number of vertically movable members to which depend therefrom to terminate in pads 18. A number of longitudinally spaced and aligned rollers 20 are provided between the rails 10 which engage the under side of the stock tubing A to support it in a horizontal position during the transforming operation.

Each roller 2% is rotatably supported on a shaft 22 transversely positioned relative to rails 10. The ends of each shaft 22 are supported by a bifurcated upper end portion 24 of a piston rod 26. Each piston rod is connected to a piston 28 that is slidably movable in a first hydraulic cylinder 30, and the lower end of each cylinder Stl is formed with a lug 32. Each cylinder 30 is pivotally supported on a mounting 34 affixed to base 13, with each mounting 54 having a pin 36 extending horizontally through a transverse bore 35 formed in lug 32.

Each of the first hydraulic cylinders 3%) is pivotally connected at 4%) to one end of a link 42 that is pivotally connected at 44 on the opposite end to a piston rod 46. Piston rod 46 is connected to a piston 43 in a second hydraulic cylinder t that is horizontally supported by a mounting 52 afiixed to base 13, as best seen in FIGURE 1. Upon actuation of each cylinder 5% the particular one of the first cylinders 3t) associated therewith can be pivoted to the angular position shown in FIGURE 1 to permit carriage H to move thereover as it travels along rails The right-hand portion of frameworloG supports an 7 elongate rigid plate 54, best seen in detail in FIGURES '3 and 4, that provides an elevated table on which the carriage K can move longitudinally. Two laterally spaced angle iron members 56 are rigidly afiixed to the upper surface of plate 54. Two heavy side walls 58 extend upwardly from the longitudinal edges of plate 54 and are reinforced against lateral movement by a number of up wardly extending reinforcing members 60. A rail 62 extendsglongitudinally along the interior face of one of the sidewalls 58 (FIGURE 4).

. Carriage K also includes a flat bed 64having a number of downwardly projecting first brackets as which support stub shafts 68 on which first rollers 7d are roo tatably mounted. Rollers 7 i3 rest on the horizontal legs 56a forming a part of the angle iron members 56. Carriage K also has second vertically disposed shafts 72 projecting downwardly therefrom on which second rollers 74 are rotatably mounted. Second rollers 74 roll in contact with the vertical legs 56b of angle iron members 56. Second brackets 76 project upwardly from bed 64 and support horizontal stub shafts 78 on which third rollers 81 are rotatably mounted that contact the under face of rail 62. The purpose of the above described roller support for carriage K will be explained hereinafter.

A gear reduction unit 82 is mounted on bed 64, and shaft L forms a part of this unit. Carriage K also includes a first hydraulic motor 84- that transmits rotative power to a torque measuring device 86, which measuring device in turn transmits power to gear reduction unit 82 to drive shaft L. The motor 84, measuring device 86, and unit 82 are all commercially available items, and therefore no detailed description thereof is required.

The right-hand ends of side walls 58 are closed by a heavy cross piece 83 in which a bore 9! is formed through which a heavy piston rod 92 extends. The lefthand end of rod 92 (FIGURE 2) is provided with a first flange )6 that is removably connectible to a second flange 98 mounted on the right-hand side of gear reduction unit 82.

One end of a horizontally disposed elongate hydraulic cylinder 16% is in abutting contact with cross piece 88. Piston rod 92 is connected to a piston 1432 which is slidably movable within the confines of cylinder 100. Cylinder 1% is supported by a number of vertically adjustable tripods 193, or other suitable supporting means. By controlling the fiow of hydraulic fluid under pressure to cylinder 1%, the carriage K can be moved longitudinally on the right-hand end portion of framework G (FIGURES l and 2), and a desired first force F4 is exerted on the shaft L.

A longitudinally extending passage 104 extends through the jaw mechanism Q, which passage is of sufficient transverse cross section to permit mandrel B to slidably move therein when the jaw mechanism grips stock tubing A. The left-hand end portion of shaft L and the right-hand end portion of mandrel B are so formed as to removably interlock at 1% and be so held by cross-keying or other conventional means. Mandrel B and shaft L are so interlocked that the madrel must rotate concurrently with the shaft, and the mandrel moved either to the left or right in passage 1% as well as within the confines of tubing A as seen in FIGURE 2.

First carriage H, as can best be seen in FIGURE 6, includes a fiat bed 198 that has two longitudinally extending, laterally spaced ribs 116 of L-shaped transverse cross section that slidably interlock with longitudinally extending recessed portions 112 of rails 16. Bed 1123 supports an electric motor R9 of the Veri-Drive type having a driving pulley 114 by means of which an endless belt 116 transmits power to a driven pulley 118. By means not shown, pulley 118 rotates member I concurrently therewith. A U-shaped shield 329 extends upwardly from bed 188 and about member I to prevent lubricant discharged on the rollsD-l, D2 and D-3 being thrown outwardly therefrom beyond the framework G during rotation of the rolls and member.

When the mandrel B is disposed within the stock tubing A, the left-hand end of the stock tubing can be removably aiiixed to the left-hand end of the mandrel (FIGURES l and 2) by any one of the means shown in FIGURES 7 to 13 inclusive. In the first means shown in FIGURES 7 and 8, the left-hand end portion oftubing A is crimped over to define a transverse, inwardly extending ring 122. A plug 124 having a central,.10ngitudinally extending tapped bore 126 formed therein is disposed inside tubing A adjacent ring 122. A stud bolt T128 is threaded intotapped bore 125. A collar 129 hav-' mg a serrated face 130 is mounted on the projecting por- V e tion of bolt 123, with the ser ated face contacting the exterior face of ring 122. A nut 132 is then threaded onto bolt 128. When nut 132 is tightened, the ring 122 is gripped between plug 124 and collar 129.

Thereafter the mandrel B can be moved longitudinally through tubing A until the free end of the mandrel contacts plug 124. The force F1 is then applied to mandrel l3 whereby the tubing A elongates and contacts internally until the interior surface thereof frictionally grips the mandrel with sufficient firmness that when the mandrel is rotated it concurrently rotates a substantial portion of the tubing therewith to impart a deforming torque F-S thereto. Should it be desired, the mandrel B can have a key 137 of non-circular transverse cross section projecting therefrom that engages a recess 13? formed in the rear of plug 136. When tubing A is so subjected to forces F-l and F5, it occupies the position on the apparatus shown in FIGURES l and 2.

The second means by which both forces F-l and F5 may be applied to tubing A (FIGURES 9 and 10) includes a cylindrical plug 135 that fits snugly within the left-hand end portion of tubing A. Two blocks 138 are provided, each of which has a semi-cylindrical surface 14% that is at least partially serrated at 142. Blocks 138 are formed with pairs of longitudinally alignable tapped bores that can be threadedly engaged by bolts 14%. Tightening of bolts 144 causes the end portion of tubing A to be gripped between plug 135 and surface 14% with the mandrel B then bein capable of applying forces F-l and F-S to the tubing.

A third means for applying forces F-l and F-S to tubing A is shown in FIGURES 11 and 12. The lefthand end portion of tubing A defines a ring shaped section 148 that abuts against the curved end section 159 of a plug 152. Plug 152 is disposed within tubing A, and has a longitudinally extending tapped bore 154 formed therein that can be threadedly engaged by a stud bolt 553 that passes through a collar 158 which is in contact with the exterior surface of section 14%. A nut 1 is mounted on bolt 156. When nut 16% is tightened, the plug and collar are drawn together to frictionally grip section M8 in the same manner as rin 122 as described above relative to the first means shown in FIGURES 7 and 8.

A fourth means for applying forces 5-; and F4? is shown in FIGURE 13 wherein the left-hand end of tubing A is so formed as to define a body shoulder 162 and tubular neck 16%. A bottle-shaped plug 166 is disposed in tubing A. Plug 155 is so formed as to have a circular tapered surface 165 which conforms to the interior surface of shoulder 152, and an elongate portion 17b that fits snugly within the confines of neck lo t. Two pressureeXerting bloclrs 138' and bolts 144' are provided which are identical in structure to blocks 13% and bolts Z44; pre viously described but are smaller in size, and when mounted on neck 16%, grip the same therebetween together with the elongate portion 170 to enable the mandrel B to exert forces 5-1 and FS on tubing A.

A fifth force applying means is shown in PlGURE 14- wherein a band 172 is welded to the left-hand end of tubing A. Two split rings 1% of L-shaped cross section are provided that abut against band 172. A tubular memher 175 forrne with a tapped bore 175, inwardly extending flange 1'58, and inwardly extending lip S9 is mounted to partially encircle the left-hand end portion of tubing A. A plug 18%- is threaded in tapped bore 176. When plug 189 is tightened by means of a nut-shaped projection 132, it pressure contacts the free end of tubing A and forces 174 into pressure contact with band The lefthand end of mandrel B can then be brought into contact with plug 180 and forces 5-1 and F-5 applied to tubing A.

A sixth force applying means is shown in FIGURE 15, which requires that one end of tubing A have a time 134 formed thereon having an external tapered surface 135 and interior tapered surface 188. A first tubular member 1% having a number of circumferentially spaced, inwardill ly projecting teeth 192 is provided with a second tubular member 11 3 formed with a number of circumferentially spaced, outwardly extending teeth 194-.

A rib 196 extends from the rear circumferential edge of tubular member 1%. Two split rings 198 having tapered interior faces 2&0 of the same angulation as surface 186 are positioned inside member 199. A plug 232 is provided which has a tapered body 2% that fits inside flare 184 and a neck 2% which projects into tubing A. The plug has a tapped recess 2% formed therein that is engaged by a threaded portion 21th of a piston 211 that is slidably movable within second tubular member 193 when the teeth 192 and 1&5 have been moved longitudinally and circumferentially into the interlocking position shown in FTGURE 15.

A number of recesses 212 extend circumferentially around plug 2&2 in which resilient sealing rings 214 are disposed, and which are in sealing contact with the interior surface of second member 193. A tapped bore 216 is formed in tubular member 193 through which hydraulic fluid under pressure can be discharged into the confines of member 1%3. When hydraulic fluid is so discharged, the piston 211 is moved away from bore 216 and the flare 13 is gripped between the split rings 1% and the tapered portion of plug 2%. The free end of mandrel B can then abut against body 266 to exert forces F4 and F-:? on tubing A. When it is desired to remove the sixth means from tubing A, exertion of the forces Fl and F-5 on mandrel B is terminated. The hydraulic pressure on piston 211 is likewise terminated. Second tubular member 1% is then rotated and moved longitudinally relative to first member 193 to

separate teeth

192 and 194. The split rings 198 are removed from first member Bil and the flare 184 moved rearwardly out of the confines of member lil through the tapped bore 236 defined by rib 1%.

A seventh force applying means is shown in FIGURE 16 wherein the free end portion of tubing A is formed into an inwardly extending section 218 having a bore 229 formed therein. A plug 222 having a curved face 224 that conforms to the interior surface of section 218 is positioned within tubing A tapped bore 22s extends longitudinally through plug 222. A collar 22% having a concave serrated face 23% is provided, which as can be seen in FTGURE 16, may be disposed in abutting contact with the exterior surface of section 233. A bore 232 is formed in collar 228 which extends longitudinally therethrough.

This seventh means also includes a cylinder 23 2 which a an end Zoe which abuts against collar 228. bore nail is formed in end 236 that is longitudinally alignable with bore 232. The end of cylinder 234 opposite end 236 13 internally tapped, and engaged by an externally threaded ring 239 that serves to hold a piston Edi? within the confines of the cylinder. Piston 24% is formed w h an enlarged portion 242 which is in slidable contact with the interior surface of cylinder 234. A number of circumferentially extending grooves 244 are formed in piston portions 242 in which resilient sealing rings 24% are seated. Also, a number of resilient sealing rings enc rcle piston 24:? and are disposed between enlarged portrons 2 22 and ring 239.

A threaded rod 25! extends from piston 240 through bore $38, and is capable of engaging tapped bore 226. A primary fluid passage 252 extends longitudinally throughpiston 24 3 to terminate in two or more branches 254 that are in communication with the interior of cylinder 234. When hydraulic fluid under pressure is discharged through passage 252. and branches 254 into the Col-171125 of ylinder 234, the cylinder tends to move to the hut to exert a pressure on collar 228, as well as gatgse plugi 222 to enert a force on the interior of section 236. Section 218 is frictronally gripped between plug in. and conar 228, and when the mandrel B is in contact with the plug it can exert forces F4 and F-fi on the tubing A. The seventh means shown in FIGURE 16 is separable from tubing A upon release of forces F-l and F-S, release of the pressure on the hydraulic fluid within cylinder 234-, and when rod 25%} is thereafter unscrewed from tapped bore 226. Of course, when this seventh force applying means is used to subject the tubing A to forces F-l and F-5, the free end of mandrel B abuts against face 256 of plug 222.

Longitudinal movement of the first carriage H on rails 19 is effected by providing the carriage with a depending lug 258 of heavy construction that is connected to the left-hand end of a piston rod 260 which extends longitudinally inside framework G to a hydraulic cylinder 262. A piston 264 is slidably mounted inside cylinder 262 and connected to piston rod 269. By control of flow of hydraulic fluid under pressure to cylinder 262, the carriage can be moved longitudinally in either direction on rails 11) at a desired rate and with a desired force.

In transforming stock tubing A to close tolerance tubing A, it is preferable to discharge a liquid on the rolls D-l, D-2 and D-3 to lubricate the same. After the liquid lubricant contacts rolls D1, D2 and D-3 as well as tubing A, it drops downwardly into a pan 27% that extends the length of framework section G1. Pan 27% is positioned below rails it), and has two opposing, downwardly tapering

bottom portions

272 and 274 that meet at a low point 276. The liquid which collects in pan 270 flows to the low point 276 therein where it is picked up by a pump (not shown) for recirculation to the rolls D1, D-2 and D3. During this process, the left-hand end of the stock tubing A, as seen in FIGURES 1 and 2, is closed by one of the seven means shown in FIGURES 7 to 16 inclusive. The right-hand end portion of tubing A (FIGURES 1 and 2) is so formed as to define a flare 184 of the configuration shown in FIGURE 15- The tubing A is thereafter rested on the rollers 24 in a horizontal position. The flared right-hand end portion of tubing A is placed in the gripping mechanism Q, and the second jaw M and catch T pivoted to the closed position by discharge of hydraulic fluid under pressure to the hydraulic cylinders N and T by means not shown.

Mandrel B is then slidably inserted in tubing A by discharging hydraulic fluid under pressure from a source (not shown) through a conduit 2% to the right-hand end portion .of cylinder 100. Fluid the may be in the left-hand portion of cylinder 10% is discharged therefrom through a conduit 29?; to a reservoir (not shown) when the piston 102 moves to the left. Movement of piston 102 to the left also results in concurrent leftward movement of second carriage K and mandrel B. This movement of mandrel B continues until the left-hand end thereof abuts against the particular one of the seven closing means (FIGURES 7-16) being used to close the lengths of tubing A on rollers 20.

The pressure on the hydraulic fluid in cylinder 1% is so regulated that the force F-l exerted 'on tubing A is less than the force required to longitudinally stress the same above its elastic limit. Hydraulic fluid is then discharged to motor 84 through a conduit 294 to cause rotation thereof, and the shaft L and mandrel B to exert a torque-imparting force F- to the tubing A. After hydraulic fluid flows through motor 84 it is returned to a reservoir (not shown) through a conduit 296. The

combined forces F-l and F-S are suflicient to stress the stock tubing A above its elastic limit. Rolls D1, D-2 and 13-3 are brought into pressure contact with the exterior surface of stock tubing A to exert-a force F-2 thereon. V V

Hydraulic iiuid under pressure is discharged to motor 109 on carriage H through aconduit 298 from a source (not shown) to cause the motor to rotate member I about tubing A and subject the rollers D1, D-2 and D'3 to a force F4, as shown inFIGURE 18. hydraulic fluid under pressure from a source (not shown) is discharged to the left-hand end ofhydraulic cylinder 2 62 through a conduit 3% to causepiston 264 to move Also,

12 to the right, with concurrent movement of first carriage H to the right as seen in FIGURES 1 and 2, and a force F3 being imparted to the tubing A, as shown in FIGURE 17.

The steps described above are continued until the rolls D-1, D-2 and D3 have traversed the length of the stock tubing A when supported as shown in FIG-

URES

1 and 2. A liquid which serves as a lubricant, such as an emulsion of oil and water, is discharged by conventional means (not shown) onto the rolls D-l, D-2 and 13-3 as they rotate about tubing A, which discharged liquid drops into the pan 270 where it flows to the low point 276 thereof. The liquid drains from pan 279 trough a conduit 304 and is recirculated to the rolls D1, D-2 and D-3 by means not shown.

After the rolls D1, D-2 and D-3 have traversed the length of tubing A, the stock'tubing has been transformed to close tolerance tubing A having a smooth external wall surface C-2 that occupies the position relative to mandrel B shown in FIGURE 17. Should it be desired to reduce the wall section of tubing A further, the rolls D-l, D2 and D3 are adjusted at the end of the first traverse to re-exert the force 5-2 on the surface C2, and the carriage subsequently moved from right to left until the rolls have traversed the length of tubing A, while maintaining the forces F-l and F-5 thereon. This traversal of rolls D-l, D-2 and D-3 of tubing A is repeated until the wall thickness of tubing A is reduced to the desired degree. second traversal of tubing A by the rolls D-l, D2 and D3, the re-exerted force F-Z can be either of the same magnitude as initially exerted, or reduced or increased as determined by the physical characteristics of the metal defining tubing A as well as by the degree of further reduction of wall thickness desired.

After the stock tubing has been transformed to close tolerance tubing A, the exertion of forces F-1,-F2, F-3, F-4 and F-S thereon is terminated. The carriages H and K are positioned as shown in FIGURES l and 2, and the mandrel B is withdrawn from tubing A by actuation of hydraulic cylinder 100. Tubing A is then removed from the apparatus shown in FIGURES 1 and 2 by reversingthe steps previously described.

In carrying out the process, it is normally desirable that .the transformed close tolerance tubing A contract sufliciently throughout the length thereof with concurrent transverse expansion whereby the mandrel B can be longitudinally withdrawn thereform. Therefore, care must be taken that the forcesF-l, F-2, F-3, F-4 and F-S are applied to the stock tubing A to such a degree that after the tubing has been transformed to close tolerance tubing A, the latter still has suflicient elasticity to contract longitudinally and expand radially to automatically free itself of the mandrel B after the transforming forces are released therefrom.

However, in some instances it isdesirable to protect the exterior surface of an elongate member with a layer of metal having'certain desirable physical characteristics, such as resistance to corrosion, temperature resistance, or the like. For example, it may be de sired to protect an elongate steel structural member with a sheet of 'zinc covering the external surface thereof. The elongate member B to' be protected is substituted for the mandrel B. The process described hereinabove is then carried out, using the elongate member B as a mandrel as illustrated in FIGURE 20, but forces F-i, F-2, F-3, F-4 and F-5 are so applied to the zinc tubing that its longitudinal elasticity is substantially exhausted, with the transformed zinc tubing continuing to remain in pressure contact with the member B.

The structural member, of course, can beformed of r i any material possessing suflicient structurm strength to act as a column during application of the force F-l to Onthe circular in transverse cross section if the rolls D1, D-2 and 13-17 are laterally movable as they apply force F2 to the tubing A to be stressed into pressure contact with the exterior surface of the structural member taking the place of mandrel B. Such lateral movement of rolls D-l, D-2 and D-S could be effected by supporting them on the ends of piston rods that are at all times urged inwardly toward the tubing A. The piston rods would be slidably movable in radially positioned hydraulic cylinders (not shown) supported by the member I.

By means of the method above described it is possible to fabricate multi-ply tubing as shown in FIGURE 21. As an illustration, close tolerance tubing A formed from titanium could be disposed on the mandrel B, a second length of tubing Z formed from stainless steel could then be disposed in an enveloping position thereover, and by application of forces F-Il, F-Z, F-3, F-- and 5-5, the stainless steel tubing could be stressed to remain permanently in pressure contact with the titanium tubing. A third length of copper tubing is then caused to envelop the stainless steel tubing and stressed into permanent ressure contact therewith. Multi-ply tubing has the advantage that it permits the use of extremely thin-walled tubing of metals such as titanium, vanadium, columbium, zirconium, and the like, having desirable physical properties, but which to date have enjoyed but limited commercial use due to the high cost thereof. When such thin-walled tubing is used, the relatively inexpensive stainless steel tubing, which may be of any desired wall thickness, acts as a reinforcement to prevent damage thereto.

While the close tolerance tubing formed by the process of the present invention is used for such conventional purposes as pump barrels, aircraft chair legs, and the like, it is ideally adapted for new uses that are constantly coming to the fore. As an example, it has recently been found that greas-eless zirconium bearings coated with a layer of blue-black zirconium dioxide can be used advantageously in high temperature water and steam application. A true cylindrical surface is most desirable in such bearings. Such bearings can be formed from stock zirconium that has been transformed to close tolerance tubing. The dioxide can be formed on the stock tubing prior to the transforming operation. From experience it has been found that the layer of dioxide is thinned concurrently with the elongation of the stool; tubing to close tolerance tubing.

The hydraulic circuit, as may best be seen in Fl *URE 19, includes a number of fixed displacement pumps identified by the numerals 5 52, 354, 35s, 35 35%, 362 and 354. As the hydraulic circuit is somewhat complicated, the components thereof are indicated by loint Industry Conference graphical symbols.

The right-hand end of tubing A, as seen FlGURE l, has a flare A ion :1 thereon, with the exterior surface of the ilare being gri ped by interior tapered surfaces defined on the jaw members M and R (FTGURE l9). A punch 356 in the form of a heavy tubular member is provided which has a tapered end that engage interior surface or" hare A" when engaged by jaw members M and R. A bore 3% is fora ed in pa. :1

J'CQ which is of sufficient transverse cross section as to permit mandrel B to be slidably mounted therein. punch 356 is slidably mounted in openings formed in the ends or" a hydraulic cylinder as shown in l9, and a piston is slidably mounted in cylinder 37?. that is rigidly connected to punch Pump 351' is actuated oy air under pressure, this pump is connected by a conduit to a source 3'75 of air under pressure. By means of a conduit the conduit 37- comrnunicates with a pressure relief valve Pump 33% has a suction line extending to a reservoir 386 for hydraulic fluid. A iiuid discharge line 33% extends from pump to one connect on of a three-position, manually operable, directional valve 39: 9 having 14 four connections. A return line 352 extends from valve 390 to reservoir 771, from which pump 364 can draw fluid. Lines 3-58 and 392 communicate through valve 395? when the valve is in the central position shown in FIGURE 19.

Two conduits 394 and 3% extend from valve 390 to opposite interior end portions of cylinder 372. When valve 3% is moved to the left, fiuid communication is established between conduits 3% and 396, as well as between return line 392 and conduit 394. Fluid under pressure is then discharged into cylinder 372 to move piston 37 i and punch 3&6 to the left, and the tapered end 368 of punch 365 is in pressure contact with the interior surface of flare A. Due to this contact, flare A is gripped between the punch and tapered faces of jaw members M and R, and may have tension applied thereto by the rel B, as previously explained. By moving the valve Si l to the right, the direction of fluid flow is reversed and the piston 374 and punch 356 are moved to the right. Pump 35b is capable of supplying fluid under pressure up to 4600 lbs. psi.

lurnp 352 is driven by a prime mover 4%, preferably an electric motor, through a drive shaft 4&2. The suction side of pump 352 is connected by a conduit 4% to reservoir 3%. A fluid discharge line 4% extends from pump 352 to a connection on a manually operable threeposition directional valve ess having a closed center. A conduit 41%} extends from a second connection on valve 4% to return line 392..

Conduits

412 and 414 are attached to the other two connections on valve 4498 (F16- URE 19). Discharge line 4% has a check valve 415 therein with a junction 4135a downstream therefrom. A junction point liib is located in discharge line 4il6 upstream from check valve 415.

Conduit 414 terminates in a junction point 414a from which a conduit 416 extends to the right-hand interior of cylinder N. When valve 4% is moved to the left, fluid flows therethrough from discharge line 4% to conduit 53 and thence through junction point 414a and conduit 416 to the right-hand interior of cylinder N. Cylinder N has a piston 41S therein which is moved to the left as fluid so enters, and concurrently moves a piston rod Piston rod 41s) is pivotally connected to jaw M, as best seen in FIGURE 5. When rod 42! is moved to the left, the jaw M is pivoted until it is closed and in pressure contact with jaw R. The inlet side of a sequence valve 424 is connected by a conduit 4-26 to junction point 422a, and the discharge side of valve 4-24 is connected by a conductor to a junction point 428a. The right-hand interior of cylinder T is connected by a conduit to junction point 428a.

After the jaw member M is seated on jaw R, pressure builds up in conduit 422' and junction point 422a whereby fluid discharges through conduit 42S, junction point 423a conduit 43% to the right-hand side of cylinder T. The cylinder T has a piston 432 therein that is connected to a piston rod extending to latch T, as may be seen FIGURE 5. As fiuid is discharged into the right-hand side of cylinder T, the latch T is pivoted clockwise to engage jaw M and hold it in a closed position.

Conduit 412 extends from the left-hand interior of cylinder T to a connection on valve 415%, and when valve is moved to the right,

conduits

414 and 410 are placed in communication. Also, discharge line 406 and conduit 412 are placed in communication. Fluid discharges into the left-hand side of cylinder T to move piston a and piston rod 434% the right to pivot latch T counterclockwise, out of engagement with jaw R. Fluid on the right-hand side of piston 432 is forced out of cylinder T as piston 4 2 moves to the right. This fluid as it discharges flows through conduit 436, junction point 428a, a conduit ess, check valve 438, conduit 440 to junction point 4232a. The fluid from junction point 422a flows through conduit 422, junction point 414a, conduit 414 valve 4% to conduit 41%, which connects to return line 392 at junction point Elba.

A conduit 442 extends from a junction point 412a in conduit 412 to a junction point 442a. Junction point 442a is connected by a conduit 444 to a second sequence valve 446, the discharge of which is connected by a conductor 448 to the left-hand interior of cylinder N. After the piston 432 has moved to the rightin cylinder T its maximum distance, the pressure on fluid in conduit 442 builds up to the extent that fluid flows through valve 446 and conductor 448 to move piston 418 and piston rod 420 to the right, and pivot jaw M clockwise to the open position. 7

A conduit 450 extends from junction point 448a to a check valve 452 which in turn is connected by a conduit 454 to the junction point 442a. When piston 418 in cylinder N is moved to the left, fluid in the left-hand end portion of the cylinder, as may be seen in FIGURE 19, discharges therefrom through conductor 448, conduit 450, check valve 452, conduits 454 and 442, junction point 412a and valve 408 to condiut 410.

Junction point 406a in the discharge line 406 from pump 352 has a conduit 460 extending therefrom to a maximum pressure valve 462. When the pressure on fluid in line 406 exceeds that for which valve 462 is set, fluid discharges through the valve. The outlet of valve 462 is connected by a conduit 464 to junction point 392a in return line 392. In FIGURE 19 it will be seen that junction point 407 has a conduit 466 extending therefrom to a junction point 466a which in turn is connected by a conduit 468 to an accumulator 470. A conduit 472 extends from junction point 4664': to a check valve 474, the outlet of which is connected by a conduit 476 to junction point 388a. A solenoid 478 when energized from a normally open electric circuit (not shown) maintains the check valve in a closed position. A pressure switch 480 is connected by a conduit 482 to junction point 38% in discharge line 388.

Fluid from pump 352 is used to initially move piston 374 and punch 366, for pump 352 has a substantially higher fluid discharge rate than pump 350. However, after the pressure in line 388 from pump 350 has risen to a predetermined value, the pressure switch 480 is closed and the solenoid 478 energized. Check valve 474 is then closed, and the cylinder 372 thereafter supplied with fluid at high pressure from pump 350.

The discharge pump 354 is connected to a conduit 484 that extends to junction point 484a. A conduit 486 extends from junction point 484a to one connection of a manually operable, two-position shut-off reverse valve 488. The other connection of valve 488 has a conduit 490 extending therefrom to a three-position, four connection directional valve 492. When valve 492 is in the center position shown in FIGURE 19, conduit 490 and a conduit 494 extending to a junction point-392b in return line 392 are in communication. Valve 492 is preferably solenoid operated. The other two connections of valve 492 are connected to the

conduits

294 and 296 leading to the hydraulic motor 84 used in applying torque to the mandrel B and tubing A. The inlet of a maximum pressure valve 496 is connected by a conduit 498 to junction point 484g. Fluid at the pressure for which valve 496 is set, discharges therefromto a conduit 500 that extends to junction point 500a.

' A conduit 502 extends from junctionpoint 50th: and has four junction points 502a, 502b, 502c and 502d therein, which junction points are connected by conduits I 504,506, 508 and 510 respectively to the inlets of four two-positiomtwo connection shut-ofl valves 514, 516, 518

' and 520. The second connections of valves 514-520 are 'joined by

conduits

524, 526, 528 and530 to the inlets of four maximum'pressurevalves 534, 536, 538 and 540,

' each set for a'dilferent pressure. The discharge sides of '-valves 534, 536, 538 and 540 are connected to a conduit discharge of valve 546 is connected to conduit 542. Valve 546 is set for the maximum fluid pressure that will be utilized in driving the hydraulic motor 84. Valves 534, 536, 538 and 548 are set for lesser pressures, preferably in steps of 300 lbs. p.s.i., with the pump 354 having a a working pressure of 2000 lbs p.s.i. Excess fluid is discharged from valve 496 through a conduit 550 to a junction point 542a in conduit 542.

The carriage H and the rotating member I mounted thereon are moved longitudinally on the framework G by hydraulic fluid discharged under pressure from the pumps 356 and 358 to the cylinder 262. A heavy, threeposition directional valve 560 is provided that has four connections and a closed center. The

conduits

300 and 301 lead from the interior end portions of cylinder 262 to two of the connections on valve 560. Pump 356 is capable of discharging fluid at a minimum of 2000 lbs. p.s.i. therefrom when the drive shaft 561 is rotated by a suitable prime mover 562 such as an electric motor. The drive shaft 564 of pump 354 previously mentioned is rotated by a prime mover 566, which also is an electric motor. Fluid discharges from the pump 356 into a conduit 568 extending to a junction point 568a. A conduit 578 extends from junction point 568k to one connection on a three-position, four-connection directional valve 572 that is solenoid-operated and acts as a pilot valve to control the position of the directional valve 560. When solenoid 574 of valve 572 is electrically energized, the valve is moved to the right and fluid communication established between the conduit 570 and a pilot line 576 that extends from the valve 572 to the hydraulic component 578 of valve 560. When component 578 is so energized, the valve 560 is moved to the left, and fluid communication is established by the valve between the conduit 300 and a conduit 580, as may best be seen in FIGURE 19.

A conduit 582 extends from junction point 568a to a check valve 584 which in turn is connected by a conduit 586 to one connection of a two-position, four-connection shut-ofl valve 588 that is preferably operated by a solenoid 590. A second connection of the shut-off valve588 is connected to a conduit 592 that extends to a junction point 592a. A conduit 594 extends from junction point 592a to a second junction point 594:: in return line 392. A junction point 582a is situated in conduit 582 between junction point 568a and the check valve 584, which junction point is connected by a conduit 596 to a maximum pressure valve 598, the discharge outlet of which is connected by a conduit 680 to the junction point 592a.

Two pressure-compensated flow control valves identified by the

numerals

602 and 604 are connected by conduits 606 and 608 respectively, to the two remaining 542 which extends to a junction point392c in return line "392. A conduit 544 extends from junction point 509a to the inlet of a maximum pressure valve 546, and the connections on valve 588. Two conduits 610 and 612 extend from the discharge outlets of

valves

602 and 604 respectively, to two check valves 614 and 616. Check vaives 614 and 616 are connected by conduits 618 and 620 to a junction point 622 from which a conduit 624 extends to a junction point 624a. Junction point 624:: is connected to conduit 580 as shown in FIGURE 19.

When hydraulic component 578 is energized, the valve 560 is moved to the left and fluid communication is established between the

conduits

580 and 300. Fluid then flows from valve 560 into cylinder 262, with the piston 264 and piston rod 268 moving to the right, together with the carriage H and the rotating member I. When it is desired to move the carriage H rapidly, such as in return ing it from one end of the framework G to the other, fluid from pump 358 is employed. Pump 358 is capable of exerting a pressure of 350 to 500 lbs. p.s.i., and has a rate:

of discharge considerably greater than that of pump 356. The drive shaft 638 of pump 358 is driven by a prime mover 632 which normally is an electric motor. A conduit 634 is connected to the discharge side of pump 358 and extends to a junction point 63411.

A maximum pressure valve 636 is provided and is connected by a conduit 633 to junction point 634a. The discharge outlet of valve 636 is connected by a conduit 640 to a junction point 592a, and a conduit 642 extends from junction point 634a to a check valve 644. Fluid flowing through check valve 644 enters a conduit 646 that is connected to a junction point 624a. When a solenoid 656 of valve 572 is electrically energized by an electrical circuit (not shown), the valve is moved to the left to establish communication between the conduit 570 and a pilot line 652 that extends to a hydraulically operated component 6S4 forming a part of the valve 569. When component 654 is energized, the valve 566 is moved to place the conduit 530 in communication with conduit 300 whereby fluid flows into the hydraulic cylinder 262 to move the piston 264, piston 26%), carriage H and the rotatable member I to the right, as shown in FIGURES 1 and 2. When piston 26% so moves to the right, fluid in the right-hand portion of the cylinder 26%) discharges into the conduit 361 and valve 566 to enter a conduit 66% that extends to a junction point 392d in conduit 392 (FIGURE 19). A conduit 662 extends from a fourth connection on valve 572 to a junction point 666a in conduit 66%}.

By means of this hydraulic arrangement the pump 358 can supply fluid at low pressure but at substantial volume to rapidly move the carriage H on the framework G. High pressure fluid at relatively low volume is supplied by the pump 356 to the cylinder 262 to move the carriage H longitudinally on the support G when the member I is rotating, and while the wall thickness of tubing A is being reduced.

The mandrel B and second carriage K are moved longitudinally on the framework G by a piston rod 92 which is connected to a piston 1622 that is slidably movable in a cylinder 16%. The two conduits 2% and 292 are connected to the interior end portions of cylinder 19% as well as two connections on a four-connection directional valve 663 having a closed center. Valve 663 is or" heavy construction and operated by two hydraulic components 664 and 666. A second four-connection directional valve 668 that is operated by two solenoids 6'76 and 672 is provided. A conduit 674 leads from one connection of valve 668 to junction point 568:: in discharge line 563. When solenoid 676 is electrically energized by a circuit (not shown) the valve 668 is moved to the right and communication is established between the conduit 674 and a pilot line 676 that leads to the hydraulic component 664 to supply fluid under pressure thereto, with the component thereafter moving the valve 663 to the left to establish communication between a fluid supply line 686 and the conduit 292. Fluid at either relatively high pressure and low volume or relatively low pressure and high Volume can be supplied through a conduit 6% to move the second carriage K and mandrel B relative to the framework G, as shown in FIGURE 2. \Vhen the solenoid 672 of valve 668 is electrically energized, the valve is moved to the left and fluid communication is established between the conduit 674 and a pilot line 684 that extends to the hydraulic component 666.

Valve 662 is moved to the right when component 666 is supplied with fluid under pressure to establish communication between conduits 689 and 290 whereby fluid under pressure discharges into the right-hand end portion of the cylinder 1% and moves the carriage K. and mandrel B to the left, as shown in FIGURES 1 and 2. Conduit 630 terminates in a junction point 689a from which a conduit 688 extends to a check valve 6% that is connected by a conduit 692 to the discharge side of pump 360.

Conduit 622 has a junction point 62a therein that is connected by a conduit 694 to the inlet side of a maximum pressure valve 696. The discharge outlet of valve 696 is connected by a conduit 698 to a junction point 32e in condu t 392. The drive shaft 6?? of pump 360 is driven by a prime mover 699 which is preferably an electric motor. By use of this hydraulic 15 system, the pump 362 can be used to supply fluid at relatively high volume and low pressure to rapidly move the carriage K longitudinally on the framework G as required.

The drive shaft 700 or" pump 362 is driven by a prime mover 792 that is preferably an electric motor. The discharge of pump 362 is connected to a conduit 764 that extends to a junction point 704a, which in turn is connected by a conduit 766 to a maximum pressure valve 7% from which hydraulic fluid at a predetermined pressure discharges through a conduit 710. Surplus fluid discharges through the maximum pressure valve 798 into a conduit 712 that is connected to a junction point 392 in line 392.

Conduit 716 extends to a junction point 716a from which a conduit 712 extends and in which junction points 712a, 7121), 7120, 712d and 712e are provided. These latter junction points are connected by

conduits

714, 716, 718 and 72% respectively, to two-position, twoconnection solenoid-operated

valves

724, 726, 728 and 730. Five

pressure reducing valves

732, 734, 736, 738 and 746 are provided, the discharge outlets of which are connected to the fluid inlets of valves 734740 by

conduits

744, 746, 748 and 759 respectively. Valve 732 is connected to junction point 712e by a conduit 752. Each of the valves 732-746 is set for a different pressure. For example, valve 732 may be set to pass fluid therethrough at 3006 lbs., valve 734 at 2700 lbs., valve 736 at 2400 lbs., valve 738 at 2100 lbs., and valve 741 at 1800 lbs. When one of the solenoids of valves 724- 739 are energized by an electric circuit (not shown), the valve is moved to the right and fluid can flow from the conduit 712 to the particular pressure-reducing valve associated with the solenoid-operated shut-ofl valve that is in the open position. The particular one of the valves 724-736 that is open determines the pressure of the fluid in a conduit 76d extending from the junction point 704a to a pressure-compensated flow control valve 762, which is connected by a conduit 764- to junction point 680a. A conduit 766 extends from valve 762 to a junction point 766:: that is connected by a conduit 768 to a junction point 392g in line 392. A conduit 769 leads from one of the connections in valve 663 to junction point 766a. Conduit 768 has a junction point 768a therein having a conduit 70 that extends therefrom to one of the connections on valve 668, as may best be seen in FIGURE 19.

Return line 392 terminates in a first reservoir 771 from which fluid is withdrawn by a suction line 772 connected to the pump 364. Pump 364 has a drive shaft 774 which is driven by a prime mover 776 that may be an electric motor, or the like. The discharge outlet of pump 364 is connected to a conduit 778 that terminates in a heat exchanger 789.

Power is supplied to the heat exchanger 783 through a drive shaft 732 that is driven by a prime mover 784, which may be an electric motor or the like. Fluid discharged from the heat exchanger flows through a conduit 736 to a filter 788. The discharge side of filter 788 is connected by a conduit 790 that discharges fluid to the reservoir 386. The suction sides of

pumps

354, 356, 358, 366 and 362 are connected to

conduits

72, 794, 796, 798 and 360 respectively that extend to reservoir 386.

A separate hydraulic system that furnishes lubricant to the rolls D-l, D-2 and 13-3 as they revolve about the tubing A is shown in the lower portion of FIG- URE 19.

After the lubricant has contacted the rolls D-l, D-2

and D-3 it is returned to a reservoir 812 from which it is drawn through a conduit 814 to a fixed displacement pump 816. The drive shaft 813 of pump 816 is driven by a prime mover 826, such as an electric motor. A conduit 622 extends from the discharge side of pump 816 to a reservoir 824 from which lubricant is withdrawn through a conduit 826 connected to the suction side of a fixed displacement pump 828. A drive shaft 83%) of pump 828 is driven by a prime mover 832, preferably an electric motor. The discharge side of pump 828 is connected to a conduit 834 that leads to a filter 836. A conduit 838 extends from filter 836 to a reservoir S40. Lubricant is withdrawn from reservoir 840 through a conduit 842 that extends to the suction side of a fixed displacement pump 844. A prime mover 846, such as an electric motor, drives a shaft 848 of pump 844.

A conduit 859 extends from the discharge side of pump 844 to a filter 852, which filter is in turn connected by a conduit 854 to a pressure-compensated flow control valve 856. A conduit 858 extends from the discharge side of valve 856, and is in communication with rolls D-1, D2 and D-3. A pressure gauge 860 is connected by a conduit 862 to conduit 858. A pressure gauge 864 is connected by a conduit 866 to conduit 484 leading from pump 354. Also, a pressure gauge 868 is connected by a conduit 870 to conduit 760 through which fluid is discharged from pump 362. The gauges are preferably mounted on a panel board 872 as shown in FIGURE 1.

Although the process and apparatus herein shown and described are capable of achieving the objects and providing the advantages hereinbefore mentioned, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that I do not mean to be limited to the details of construction herein shown and described other than as defined in the appended claims.

I claim:

1. A method of transforming stock tubing formed of a cold workable metal capable of strain hardening to close tolerance tubing of a lesser wall thickness and improved physical characteristics both longitudinally and transversely, comprising the steps of: removably gripping a first end of said stock tubing and holding the same in a fixed position; moving a first elongate rigid body through said stock tubing until one end of said body is disposed adjacent the second end of said stock tubing; removably connecting said second end of said stock tubing to said adjacent end of said first body; moving said first body longitudinally relative to said fixed position .to exert a first tensional force on said stock tubing; rotating said first body relative to said fixed position to exert a torsional twist on said stock tubing; positioning a plurality of circumferentially spaced hard surfaces about said stock tubing; moving each of said hard surfaces into contact with the exterior surface of said stock tubing; exerting a force on each of said hard surfaces to cause the same to apply a second radially directed force to said stock tubing to indent the surface of said stock tubing and define a pressure area thereon; moving each of said hard surfaces longitudinally relative to said first body with a third longitudinally directed force; moving said hard surfaces about said stock tubing with a fourth circumferentially extending force to sequentially subject the exterior surface of said stock tubing to said pressure areas, with the combined magnitude of said first, second, third and fourth forces and said torsional twist being sufiiciently great to cause permanent elongation and thinning of the side walls of said stock tubing, which elongation and thinning is accompanied by a strain-hardening of said metal defining said stock tubing in a helical pattern; ceasing to apply said first, second, third and fourth forces and said torsional twist to said stock tubing after it has been transformed to close tolerance tubing of a desired wall thickness; allowing said close tolerance tubing to contract longitudinally and expand radially; disconnecting said second end of said tubing from said adjacent end of said elongate body; removing said elongate body from the confines of said tubing; releasing said grip of said first 20 end of said tubing; and carrying out said steps within a temperature range which permits strain hardening of said metal defining said tubing when it is subjected to sufficient force to permanently deform the same.

2. A method as defined in claim 1 wherein the combined magnitude of said first force and said torsional twist exerted on said stock tubing is sufiicient to cause permanent deformation of said metal defining said tubing.

3. A method as defined in claim 1 wherein the combined magnitude of said first force and said torsional twist exerted on said stock tubing is sufficient to stress said metal defining said tubing above the yield point thereof.

4. A method as defined in claim 1 wherein the mag nitude of said second forces'exerted on said stock tub ing is sufficient to sequentially press the interior surface of said pressure areas into pressure contact with the exterior surface of said elongate body.

5. A method as defined in claim 1 wherein said hard surfaces are barre shaped, and includes the further step of rotatably supporting said hard surfaces as they are moved around said stock tubing to subject the exterior surface of said tubing to a cross-rolling action.

6. A method as defined in claim 1 wherein said hard surfaces are barrel-shaped, and includes the further steps of rotatably supporting said hard surfaces as they are moved around said stock tubing to subject the exterior surface of said tubing to a cross-rolling action, and moving said surfaces about said stock tubing in the same direction as that in which said torsional twist is applied thereto.

7. A method as defined in claim 5 which includes the further step of longitudinally traversing said stock tubing with said hard surfaces first in one direction and then in an opposite direction with said second force being applied to said tubing until it has been transformed to close tolerance tubing of a desired wall thickness.

8. A method as defined in claim 1 wherein said hard surfaces are of elongate, generally cylindrical configuration, and includes the further steps of rotatably supporting said hard surfaces as they are moved around said stock tubing to subject the exterior surface of said tubing to a cross-rolling action, and rotating said surfaces about said tubing.

9. A method of enveloping an elongate rigid body in tubing formed from a cold workable metal, comprising the steps of: removably gri ping a first end of said tubing and holding the same in a fixed position; moving said elongate body through said tubing until one end of said body is adjacent the second end of said tubing; connecting said second end of said tubing to said adjacent end of said body; moving said elongate body longitudinally relative to said fixed position to exert a tensional first force on said tubing; positioning a plurality of circumferentially spaced hard surfaces about said stock tubing; moving each of said hard surfaces into contact with the exterior surface of said tubing; exerting a force on each of said hard surfaces to cause the same to apply a second radially directed force to said stock tubing to indent the surface of said tubing and define a pressure area thereon; moving each of said hard surfaces longitudinally relative to said elongate body with 'a longitudinally directed third force; moving said hard surfaces about said tubing with a circumferentially directed fourth force to sequentially subject the exterior surface of said tubing to said pressure areas, with the combined magnitude of said first, second, third and fourth forces and said torsional twist being sulficiently great to cause permanent elongation and thinning of the side walls of said tubing, as well as to :force the interior surface thereof into pressure contact with said elongate member; continuing to apply said first, second, third and fourth forces and said torsional twist to said tubing until said tubing has been deformed to the extent that it remain in pressure contact with said elongate member after said forces and torsional twist are no longer applied thereto; ceasing to apply said first, second, third and fourth forces and said torsional twist to said tubing; and releasing said first end of said tubing from said fixed position.

10. A method as defined in claim 9 wherein said elongate body is a tubular member.

ll. The method of producing a tubular member of accurate and uniform wall thickness comprising the steps of: inserting an elongate rigid body within the confines of a length of stock tubing formed of a metal that strain hardens when subjected to a force which permanently deforms the same; afiixing one end of said body to a first end of said stock tubing; gripping a second end of said stock tubing and maintaining the same in a fixed position; moving said body longitudinally and rotationally relative to said fixed position with a longitudinally directed first force and a torsional twist to permanently elongate said stock tubing; exerting a plurality of radially directed second forces on the exterior surface of said stock tubing to define a plurality of circumferentially spaced indented pressure areas on the exterior surface thereof, with the interior surfaces of said pressure areas being forced into pressure contact with the exterior surface of said body with sufiicient force to receive the same finish as that of said exterior surface; moving said pressure a eas longitudinally relative to said elongate body by means of a longitudinally directed third force; rotating said pressure areas about said stock tubing with a circumferentially directed fourth force; continuing to apply said first, second, third and fourth forces and said torsional twist to said stock tubin until the entire exterior surface of a desired length of said tubing that is to be formed to said uniform wall thickness is sequentially subjected to said pressure areas; ceasing to apply said first, second, third and fourth forces and said torsional twist to said tubing after said desired length thereof has been formed to said uniform thickness; disconnecting said body from said first end of said tubing; permitting said tubing to contract longitudinally and expand transversely to move out of pressure contact with said body; withdrawing said body from said tubing; and releasing said second end of said tubing from said fixed position.

12. The method as defined in claim 11 which includes the further step of slipping a second length of tubing of a cold workable material onto said length of tubing that has been transformed, and repeating said method on said second length of tubing to deform the same into pressure contact with said length of tubing on which it is mounted to provide multi-ply tubing.

13. An apparatus for ransforming stock tubing formed of a cold workable metallic material capable of strain hardening to close tolerance tubing of lesser wall thickness and improved physical characteristics both longitudinally and transversely, comprising: an elongate frame; means for holding a first end of said stock tubing at a fixed position relative to said frame when said stock tubing is disposed in a predetermined position relative to said frame; an elongate rigid mandrel having a transverse cross section slightly less than the interior cross section of said stock tubing; means for removably holding an end of said mandrel in a fixed position relative to the second end of said stock tubing when said mandrel is slid therethrough; first means for moving said mandrel relative to said frame to cause a longitudinal first force to be exerted on said stock tubing; a plurality of hard bodies capable of being circumferentially spaced about said stock tubing when said first end thereof is held at said fixed position; second means for moving each of said bodies inwardly toward said stock tubing when said first end thereof is held at said fixed position to cause each of said bodies to exert an inwardly directed second force on the exterior surface thereof of sufdcient magnitude as to indent the exterior surface of said stock tubing; a third means for moving said bodies when in contact with said stock tubing longitudinally relative to said frame to cause a longitudinal third force to be exerted thereon; a fourth means for revolving said bodies about said stock tubing to cause a circumferentially directed fourth force to be exerted on said tubing; and a fifth means for rotating said mandrel and said second end of said stock tubing afixed thereto to subject said tubing to a circumferentially directed fifth force.

14. An apparatus as defined in claim 13 wherein said second end portion of said stock tubing is formed to define an inwardly extending ring and said means for obstructing said second end includes a plug disposed within said stock tubing in abutting contact with said ring, said plug having a tapped bore extending longitudinally therethrough; a stud bolt is threaded into said bore and projecting outwardly from said plug; a collar is provided having a bore formed therein through which said bolt extends; and a nut is threaded on said bolt to cause said ring to be frictionally gripped between said plug and collar, with the inwardly disposed end of said plug and the outer end of said mandrel when said first force is exerted on said mandrel frictionally engaging one another to the extent that said fifth force can be transmitted to said stock tubing.

15. An apparatus as defined in claim 13 wherein said means for obstructing said second end includes a plug that fits snugly with the second end portion of said stock tubing; two blocks having semi-cylindrical surfaces are provided that substantially envelop the exterior surface of the second end portion of said stock tubing, which blocks have pairs of longitudinally alignable bores formed therein, with at least one of said pairs being tapped; and two bolts extend through said bores, with said bolts when tightened drawing said blocks together to frictionally grip said second end portion of said stock tubing between sad plug and blocks to the extent that when said first force is exerted on said mandrel an end thereof friction-ally engages said plug to the extent that said fifth force can be transmitted to said stock tubing.

16. An apparatus asdefined in claim 13 wherein said second end portion of said stock tubing is formed to define a body shoulder from which a neck of said stock tubing projects, said means for obstructing said second end includes a bottle-shaped plug disposed in said stock tubing which bears against said shoulder and extends through said neck; two blocks having semi-cylindrical surfaces are provided that substantially envelop the exterior surface of a section of said neck, which blocks have pairs of longitudinally alignable bores formed therein, with at least one of said pairs being tapped; and two bolts extend through said bores, with said bolts when tightened drawing said blocks together to frictionally grip said neck and hold said plug against said shoulder to the extent that when said first force is exerted on said mandrel, an end thereof frictionally engages said plug to the extent that said fifth force can be transmitted to said stock tubing.

17. An apparatus as defined in claim 13 wherein said means for obstructing said second end includes a band welded to the exterior surface of said second end portion of said stock tubing; two split rings; a tubular member formed with a tapped bore and having an inwardly extending flange and inwardly extending lip in longitudinally spaced relationship, with said split rings being adapted to be positioned between said flange and ring, which rings when so disposed capable of being positioned in abutting contact with said band; and an externally threaded plug which engages said tapped bore in said tubular member and when tightened holds said rings in contact with said band, with said mandrel when said first force is exerted thereon frictionally engaging said plug to the extent that said fifth force can be transmitted to said stock tubing.

18. An apparatus as defined in claim 13 wherein said means for obstructing said second end portion when it is formed to define a flare includes two split rings having tapered faces adapted to seat on the exterior surface of said flare; first and second tubular members that removably interlock to envelop said flare, with said. first member removably engaging said split rings; a plug having a tapered face that can removably engage the exterior surface of said flare as well as a neck which; extends into the interior of said second end portion, with a portion of said plug slidably disposed in said second member; means for eflecting a fluid-tight seal. between said plug portion in said second member and. the interior surface of said second member; and means: for introducing hydraulic fluid under pressure into said. second member to move said plug and cause said taper to be frictionally gripped between said split rings and said plug, with said neck then being capable of having an: end of said mandrel frictionally engage the same when said mandrel is subjected to said first force to the ex tent that said fifth force can be transmitted to said stock tubing.

19. An apparatus as defined in claim 13 wherein said". second end portion of said stock tubing curves inwardly and said means for obstructing said second end includes. a plug disposed inside said stock tubing, which plug has a curved surface adapted to abut against the interior surface of said curved second end portion of said stock tubing, said plug having a tapped bore formed thereirr that extends longitudinally therethrough; a collar having a curved surface that abuts against the exterior surface of said curved second end portion; a cylinder that abuts against said collar; a piston slidably movable within said cylinder; a threaded rod extending from said piston and through said collar to removably engage said tapped bore; and means to introduce hydraulic fluid under pressureinto said cylinder to move said piston away from said stock tubing to cause said curved second end portion of said tubing to be frictionally gripped between said plug and collar, with the inwardly disposed end of said plug and the outer end of said mandrel when said first force is exerted on said mandrel frictionally engaging one another to the extent that said fifth force can be transmitted to said stock tubing.

20.'An apparatus as defined in claim 19 wherein said had bodies are rolls having bores extending longitudinally therethrough, which apparatus also includes: a plurality of shafts extending through said bores in said rolls and rotatably supporting said rolls; and a plurality of shaft supports affixed to the inwardly disposed ends of said eircumferentially spaced members, with said supports holding said shafts not only in parallel relationship but parallel to the longitudinal axis of said frame as well.

21. An appaartus as defined in claim 20 that also includes a second carriage longitudinally movable on said frame; a third prime mover mountedon said second carriage; second power transmission means mounted on said second carriage capable of being driven by said third prime mover, with one end of said mandrel being connected to said second transmission means and capable of being rotated when said third prime mover is actuated; and a fourth prime mover capable of moving said second carriage to said mandrel longitudinally relative to said hydraulically operated jaws and toward said first carriage to cause said mandrel to transmit said first force to said stock tubing, with said mandrel concurrently transmitting said fifth force to said stock tubing when rotated by said second transmission means.

22. An apparatus as defined in claim 21 wherein said means for movably supporting said movable members are pivotal connections between said frame and the lower portions of said movable members, which means for pivoting each of said movable members to either a first or second position are hydraulically operated.

23. An apparatus as defined in claim 21 wherein said means for movably supporting said movable members are pivotal connections between said frame and the lower portions of said movable members, which means for pivoting each of said movable members. to either a first or second position are power operated.

24. An apparatus as defined in claim 13 which also includes a first carriage longitudinally movable on said frame; a first prime mover mounted said first carriage; a driven member transversely disposed relative to said frame that occupies a fixedposition relative to said first carriage; transmission means on said first carriage for transmitting rotary motion from said prime mover to said driven member; a plurality of circumferentially spaced, radially positioned members movably supported on said driven member, with each of said circumferentially spaced members supporting one of said hard bodies on the inwardly disposed end thereof; and a second prime mover for moving said first carriage on said frame to cause said hard bodies to exert said third force on said stock tub ing when said hard bodies are exerting said second force on said stock tubing and said first prime mover is driving said driven member through said transmission means to exert said fourth force on said stock tubing.

25. An apparatus as defined in claim 24 wherein said means for holding a first end of said tubing at a fixed position relative to said frame are hydraulically operated jaws capable of removably gripping said first end of said stock tubing, which jaws are of such structure as to permit said mandrel to be moved therethrough when gripping said first end, and a rigid upright is provided that is aflixed to said frame and on which said hydraulically operated jaws are mounted.

26. An apparatus as defined in claim 25 that also includes a plurality of longitudinally spaced stock tubing supporting members capable of contacting the under side of said tubing to hold the same straight when it is so positioned relative to said frame to permit said jaws to grip said first end thereof; a plurality of movable members on the upper ends of which said supporting members are mounted; means for movably supporting said movable members from said frame to permit each of said movable members to occupy a first postion wherein said supporting member associated therewith contacts said stock tubing to hold the same in a straight position, and in a second position wherein said supporting member associated therewith is out of contact with said tubing and occupies a position relative to said frame wherein said first carriage can pass thereover; and means for moving each of said movable members from said first position to said'second position as required by the movement of said first carriage on said frame and fromsaid second position to said first position after said first carriage has passed over said one of said supporting members associated with said movable member.

References Cited in the file of this patent UNITED STATES PATENTS 282,718 Griffin Aug. 7, 1883 458,381 Watson Aug. 25, 1891 1,129,835 Lloyd Feb. 23, 1915 1,193,920 Peck Aug. 8, 1916 1,709,011 Fulton Apr. 16, 1929 2,108,790 Inscho Feb. 22, 1938 2,361,318 Orr Oct. 24, 1944 2,503,512 Sattele Aug. 2, 1946 r 2,679,089 Opitz May 25, 1954 2,927,372 Powell Mar. 8, 1960 FOREIGN PATENTS 9,382 Great Britain 1886

Claims

1. A METHOD OF TRANSFORMING STOCK TUBING FORMED OF A COLD WORKABLE METAL CAPABLE OF STRAIN HARDENING TO CLOSE TOLERANCE TUBING OF A LESSER WALL THICKNESS AND IMPROVED PHYSICAL CHARACTERISTICS BOTH LONGITUDINALLY AND TRANSVERSELY, COMPRISING THE STEPS OF: REMOVABLY GRIPPING A FIRST END OF SAID STOCK TUBING AND HOLDING THE SAME IN A FIXED POSITION; MOVING A FIRST ELONGATE RIGID BODY THROUGH SAID STOCK TUBING UNTIL ONE END OF SAID BODY IS DISPOSED ADJACENT THE SECOND END OF SAID STOCK TUBING; REMOVABLY CONNECTING SAID SECOND END OF SAID STOCK TUBING TO SAID ADJACENT END OF SAID FIRST BODY; MOVING SAID FIRST BODY LONGITUDINALLY RELATIVE TO SAID FIXED POSITION TO EXERT A FIRST TENSIONAL FORCE TO SAID STOCK TUBING; ROTATING SAID FIRST BODY RELATIVE TO SAID FIXED POSITION TO EXERT A TORSIONAL TWIST ON SAID STOCK TUBING; POSITIONING A PLURALITY OF CIRCUMFERENTIALLY SPACED HARD SURFACES ABOUT SAID STOCK TUBING; MOVING EACH OF SAID HARD SURFACES INTO CONTACT WITH THE EXTERIOR SURFACE OF SAID STOCK TUBING; EXERTING A FORCE ON EACH OF SAID HARD SURFACES TO CAUSE THE SAME TO APPLY A SECOND RADIALLY DIRECTED FORCE TO SAID STOCK TUBING TO INDENT THE SURFACE OF SAID STOCK TUBING AND DEFINE A PRESSURE AREA THEREON; MOVING EACH OF SAID HARD SURFACES LONGITUDINALLY RELATIVE TO SAID FIRST BODY WITH A THIRD LONGITUDINALLY DIRECTED FORCE; MOVING SAID HARD SURFACES ABOUT SAID STOCK TUBING WITH A FOURTH CIRCUMFERENTIALLY EXTENDING FORCE TO SEQUENTIALLY SUBJECT THE EXTERIOR SURFACE OF SAID STOCK TUBING TO SAID PRESSURE AREAS, WITH THE COMBINED MAGNITUDE OF SAID FIRST, SECOND, THIRD AND FOURTH FORCES AND SAID TORSIONAL TWIST BEING SUFFICIENTLY GREAT TO CAUSE PERMANENT ELONGATION AND THINNING OF THE SIDE WALLS OF SAID STOCK TUBING, WHICH ELONGATION AND THINNING IS ACCOMPANIED BY A STRAIN-HARDENING OF SAID METAL DEFINING SAID STOCK TUBING IN A HELICAL PATTERN; CEASING TO APPLY SAID FIRST, SECOND, THIRD AND FOURTH FORCES AND SAID TORSIONAL TWIST TO SAID STOCK TUBING AFTER IT HAS BEEN TRANSFORMED TO CLOSE TOLERANCE TUBING OF A DESIRED WALL THICKNESS; ALLOWING SAID CLOSE TOLERANCE TUBING TO CONTRACT LONGITUDINALLY AND EXPAND RADIALLY; DISCONNECTING SAID SECOND END OF SAID TUBING FROM SAID ADJACENT END OF SAID ELONGATE BODY; REMOVING SAID ELONGATE BODY FROM THE CONFINES OF SAID TUBING; RELEASING SAID GRIP OF SAID FIRST END OF SAID TUBING; AND CARRYING OUT SAID STEPS WITHIN A TEMPERATURE RANGE WHICH PERMITS STRAIN HARDENING OF SAID METAL DEFINING SAID TUBING WHEN IT IS SUBJECTED TO SUFFICIENT FORCE TO PERMANENTLY DEFORM THE SAME.