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Publication numberUS3863328 A
Publication typeGrant
Publication dateFeb 4, 1975
Filing dateJan 22, 1974
Priority dateOct 10, 1972
Publication numberUS 3863328 A, US 3863328A, US-A-3863328, US3863328 A, US3863328A
InventorsArntz John J
Original AssigneeCopperweld Steel Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of making a Composite steel tubing
US 3863328 A
Abstract
The specification discloses a double wall steel tubing and a method of making it which results in the production of steel tubing having a size range and wall thickness heretofore available only in a seamless tubing and possessing a uniformity of wall thickness within heretofore unattained tolerance limits. An outer welded tube is first telescoped over an inner welded tube. The two tubing sections are then mechanically bonded together as by being drawn through a sizing die in a sink pass without a mandrel or by forcing a mandrel through the inner tubing section. The composite tubing is then drawn through a second sizing die over a mandrel to produce a heavy wall tubing, equivalent in strength characteristics to single wall tubing of the seamless type.
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Description  (OCR text may contain errors)

United States Patent [191 Arntz METHOD OF MAKING A COMPOSITE STEEL TUBING [75] Inventor: JohnJ. Arntz, Shelby, Ohio [73] Assignee: Copperweld Steel Company, Shelby,

Ohio

[22] Filed: Jan. 22, 1974 [21] Appl. No.: 435,526

Related U.S. Application Data [63] Continuation of Ser. No. 295,993, Oct. 10,- 1072, abandoned, which is a continuatiomin-part of Ser. No. 126,633, March 22, 1971, abandoned.

[52] U.S. Cl 29/516, 29/520, 29/523, 138/1'51 [51] Int. Cl B21d 39/00, B23p 11/00 [58] Field of Search 29/516, 520, 523 X;

[56] References Cited UNITED STATES PATENTS 1,441,459 1/1923 Small l38/5l 1,839,964 1/1932 Harvey 29/516 UX 2,063,325 12/1936 McLeod 138/140 2,198,149 4/1940 Bangert 29/516 2,219,434 10/1940 White 1 1 29/516 UX 3,461,523 8/1969 Peehs et al 29/516 X [111 3,863,328 [451- Feb. 4, 1975 3,532,476 10/1970 Peehs et a1 29/516 X Y FOREIGN PATENTS OR APPLICATIONS 822,983 l/l938 France 138/140 858,615 1/1952 Germany 138/140 Primary Examiner-Charlie T. Moon Attorney, Agent, or Firm-Buell, Blenko & Ziesenheim [57] ABSTRACT thickness heretofore available only in a seamless tubing and possessing a uniformity of wall thickness within heretofore unattained tolerance limits. An outer welded tube is first telescoped over an inner welded tube. The two tubing sections are then mechanically bonded together as by being drawn through a sizing die in a sink pass without a mandrel or by forcing a mandrel through the inner tubing section. The composite tubing is then drawn through a second sizing die over a mandrel to produce a heavy wall tubing, equivalent in strength characteristics to single wall tubing of the seamless type.

14 Claims,-4 Drawing Figures PATENTEI] FEB 41975 SHEEI 10F 2 INVENTOR John J. Arntz METHOD OF MAKING A COMPOSITE STEEL TUBING v The present application is a continuation of my prio application, Ser. No. 295,993, filed Oct. 10, 1972, now abandoned, which application in turn' is a continuationin-part of my prior application, Ser. No. 126,633, filed Mar. 22, 1971, now abandoned.

This invention relates to composite steel tubing having a degree of wall thickness not heretofore available except in steel tubing of the seamless type, and to a method of making such composite steel tubing.

Seamless tubing is produced according to presentday methods by a process involving heating a solid tube round to a forging temperature and then forcing it with a rotary motion over a piercing point to form a hollow for subsequent cold drawing. Because it is impossible to keep the piercing point always in the exact center of the tube round during the piercing operation, a wall thickness variation or eccentricity often results. Moreover, since the tube is turning as it is being formed, a spiraling eccentricity of wall thickness may be produced. This lack of uniformity of wall thickness may be greatly reduced or refined by subsequent hot and cold finishing operations but the eccentricity is never fully eliminated.

Where tolerance limits of wall thickness permit, seamless tubing may be employed, especially in the larger size ranges. However where the application requires tubing having more exacting or restrictive tolerances of wall thickness, additional processing of the seamless tubing is required, such as machining or grinding. This additional processing is, however, impractical except in'relatively short sections.

An alternative process of making high-strength tubing is the cold drawing over a mandrel of electric resistance welded tubing. This process produces a tubing comparable in strength to the seamless tubing and characterized by a greater uniformity of wall thickness. However this process has its limitations in that tubing, having wall thicknesses exceeding dimensions of the order of 0.340 inch, is not presently practical by this method.

In accordance with the present invention, it is proposed to provide a method for producing tubing in larger diameter ranges and greater wall thicknesses than has heretofore been attainable by known colddrawing processes and equal in wall thickness to tubing of the seamless type. More specifically, it is proposed to produce tubing having wall thicknesses up to twice that presently available by the cold drawing process by the employment of a double-wall concept in which an inner tubing and an outer tubing of the same metal such as steel, are telescoped and joined into an integral tubing. This concept has been utilized variously with tubing of different metals for the purpose of providing a relatively thin layer or protective layer within or outside a relatively thick walled tubing, where the purpose of the liner is primarily for protection against chemical action or corrosion and not for the addition of physical strength.

Many of the various processes by which such doublewalled tubing of dissimilar metals are produced involve a metallurgical union or a bonding with a bonding agent of the liner to the basic tubing via a heating stage. As an example, there is described in US. Pat. No. 2,371,348 to M. G. Murray a process for making a composite tubing by heating telescoped sections of tubing of different metals to fuse a bonding agent applied therebetween, followed by insertion of a cold bar inside the inner tubing section, while still hot, to prevent separation of the outer and inner tubing sections, as cooling progresses, due to the differing temperature coefficients of expansion of the different metals.

Similarly there is described in U.S. Pat. No. 2,219,434 to H. N. White a process for making a composite tubing having an outer tubing section of nickel silver and an inner tubing section of sterling silver, which process involves a single pass of cold drawing the telescoped tubing sections through a die and over a mandrel to effect union of the two tubing sections.

The process proposed, according to the present in vention, differs from heretofore known methods of making composite tubing by reason of the fact that both outer and inner tubing sections are of the same metal, such as steel, and differences in the temperature coefficient of expansion of the telescoped tubing sections do not present a problem to be dealt with. Moreover, absence of any requirement for a bonding agent between the tubing sections, simplifies the process and avoids problems arising out of heating the assembled tubing sections.

More specifically, the proposed process involves the provision of two tubing sections of such different diameters as to enable one tubing section to be telescoped within the other, the mechanical bonding of the two tubing sections by altering the diameter of one of the tubing sections relative ofthat of the other tubing section, and the cold drawing of the united tubing sections through a die and over a mandrel to size the final prodllCt.

Alteration of the diameter of one of. the tubing sections is effected either by cold drawing the telescoped tubing sections without lubrication of the use of a bonding agent therebetween, through a die and without a mandrel to compress the outer tubing section on the inner tubing section into close contact or by'cold drawing a mandrel or plug through the inner tubing section to expand it into contact with the outer tubing section.

The proposed process thus provides a practical method for making tubing having heavy wall thicknesses conforming to heretofore unattained tolerances without requiring any special cold drawing equipment other than has heretofore been employed for tubing of lesser thicknesses.

The method for producing a compositetubing according to the present invention will be described more fully hereinafter'in connection with the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view, showing outer and inner tubing sections telescoped and hammered at one end preparatory to sink drawing;

FIG. 2 is a longitudinal sectional view, showing the composite tubing after sink drawing through a die without a mandrel;

FIG. 3 is a longitudinal sectional view, showing the composite tubing after cold drawing through a sizing die and over a mandrel; and

FIG. 4 is a longitudinal sectional view showing an alternative step to that of FIG. 2.

As will be apparent by reference to FIG. 1, the initial step in pursuing the process here disclosed is to select produce the ultimate product desired. As a matter of convenience and brevity the term outside diameter will be referred to hereafter as O.D.", the term inside diameter will be referred to as LD. and the term wall thickness will be referred to as W.T.. Let it be assumed, for example, that two tubing sections and 11 have been selected with the following dimensions:

Tubing 0.1). |.D. W.T.

It will be noted that there is a total clearance of 0.25 inch between the ID. of tubing 10 and the CD. of tubing 11, thereby enabling thetwo tubings to be readily telescoped completely as shown in FIG. I, which is the first step in the process. The tubes are nowhammered or flattened at one end with the inner tubing 1 I extending slightly outside of the outer tubing 10 and flared so as to firmly lock the two tubes 10 together. Also, the

open end of the inner tubing 11 is extended an amount, such as 12 to 18 inches, beyond the outer tubing 10 to compensate for the fact that the outer tube will elongate or grow in length to a greater extent than the inner tubing during the initial cold drawing stage or sink pass, now to be described.

Referring to FIG. v2, the sink pass consists of cold drawing the hammered or flattened ends of the telescoped sections of tubing through a die 12, which in the the inner tubing. However, with the assumed tubing dimensions the OD. of the inner tubing is larger than the assumed resultant ID. of the outer tubing. Accordingly, to accomodate the situation, the outer tubing is elongated and the inner tubingbecomes smaller in diameter. This adjustment is shown in FIG. 2, where the open end of the outer tubing 10 is shown as shifted to the right relative to the open end of the inner tubing. At this particular stage of the process, it might be said that the tubing sections, theoretically at least, form a composite tube with a 7 inch OD. and 0.75 inch W.T.

In order to avoid impairment of the mechanical bond between the ID. surface of the outer tubing and the 0D. surface of the inner tubing, no lubricant is applied to the tubing sections prior to the sink pass of FIG. 2, except that the 0D. surface of the outer tubing is lubricated.

The next step in the process involves cold drawing the composite tubing simultaneously through'a die 13 and over a mandrel 14, as shown in FIG. 3. Preceding this cold drawing operation, the composite tubing is dipped into a lubricant, without annealing the tubing however. Following the heretofore assumed dimensional relations of the tubing sections 10 and 11, die 13 may be such as to produce a 6.5 inch 0D. for the outer tubing 10 and the mandrel 14 may be such as to produce a 0.668 W.T. thus resulting in an ID. of 5.125 inches for the inner tubing section 11, which correspondingly elongates relative to the outer tubing section.

A variationof the process may be followed which involves substituting the step shown in FIG. 4 for the step shown in FIG. 2.

As will be apparent from the drawing, the step of FIG. 4 involves expansion of the inner tubing section 11 into contact with the outer tubing section 10 to effect a mechanical bond therebetween. This is accomplished in the manner illustrated by FIG. 4, that is, by pulling an appropriately sized mandrel 15 in the righthand direction through the inner tubing section 11 to expand it circumferentially into contact with the inner diameter of the wall of the outer section 10. On the basis of the original tubing dimensions, the outer diameter of the inner tubing section will be expanded 0.25 inch to match the ID. of 6.75 inches of the outer tubing section. Assuming no expansion of the outer tubing section 10, the resultant O.D. forthe composite tubing would be 7.5 inches. If diametrical expansion of the inner tubing section occurs beyond that necessary to effect a mechanical bond, then some lengthwise expansion of the inner tubing section will occur. It will be understood, therefore, that if it is desired to arrive at the same ultimate OD. for the composite pipe while em ploying the step of FIG. 4 as for the step of FIG. 2, a correspondingly reduced CD. of the outer tubing section must be employed at the start.

A further variation of the above described process may be followed, where further improvement in the mechanical bond between the tubing sections is desired. In this variation, the ID. surface of the outer tubing section is picked, that is, scored prior to the initial telescoping of the tubing sections. This scoring operation may be accomplished by pulling a tool through the inside diameter of the outer tubing section. An example of a tool suitable for this purpose is described and claimed in US. Pat. No. 3,504,513, assigned to the assignee of this application. In consequence of the scoring of the inside diameter surface of the outer tubing section, the 0D. surface of the inner tubing section is interlockingly impressed into the scored indentations of the ID. surface of the outer tubing section, thus providing a more effective mechanical bond between the two tubing sections.

In the alternative, the 0D. surface of the inner tubing section may be scored prior to the original telescoping of the tubing sections. This can be accomplished incidentally to the process of making the tubing section itself. The effect is the same as before, namely an improvement in the mechanical bond between the tubing sections of the composite tubing made in accordance with the hereinbefore describedprocess.

Tests conducted on samples of the composite tubing produced according to the herein described process have established that in both tensile and burst strength values, the composite tubing is the equivalent in performance to seamless tubing of similar dimensions.

It is to be understood that no limitations are intended with respect to the sizes of tubing which may be made by the foregoing process. However, the particular utility and advantage of the process lies in producing composite tubing of heavy wall thickness to heretofore unattained tolerance limits.

I claim:

l. The method of making a composite steel tubing comprising the steps of:

a. providing two sections of welded steel tubing of substantially equivalent wall thickness, one of which sections has an outer diameter less than the inner diameter of the other;

b. telescoping said tubing sections and locking them together at one end;

cold drawing said telescoped tubing sections through a die without a mandrel to compress the outer tubing section onto the inner tubing section thereby to produce a mechanical bond therebetween; and

d. cold drawing the united tubing sections through a sizing die and over a mandrel.

2. The method of making a composite steel tubing according to claim 1, wherein the sum of the wall thicknesses of the two tubing sections provided exceeds 0.340 inch.

3. The method of making a composite steel tubing according to claim 1, wherein one of the tubing sections provided has its mating surface scored prior to telescoping the tubing sections.

cording to claim 6, wherein the change in the diameter of one of said tubing sections is accomplished by cold drawing the telescoped tubing sections through a die without a mandrel to compress the outer tubing section onto the inner tubing section.

8. The method of making a composite steel tubing according to claim 6, wherein the change in the diameter of one of said tubing sections is accomplished by expanding the inner one of said tubing sections.

9. The method of making a composite steel tubing according to claim 6, wherein the expansion of the inner one of said tubing sections is accomplished by forcing 4. The method of making a composite steel tubing according to claim 1, wherein the outer diameter surface of the inner tubing section is scored prior to telescoping the tubing sections.

5. The method of making a composite steel tubing according to claim 1, wherein the inner diameter surface of the outer tubing section is scored prior to telescoping the tubing sections.

6. The method of making a composite steel tubing comprising the steps of:

a. providing two sections of welded steel. tubing of substantially equivalent wall thickness, one of which sections has an outer diameter less than the inner diameter of the other;

b. telescoping said tubing sections and holding them together at one end;

c. changing the diameter of one of said tubing sections so as to produce a mechanical bond therebetween; and

d. cold drawing the united tubing sections through a sizing die and over a mandrel.

7. The method of making a composite steel tubing ac a mandrel therethrough.

10. The method of making a composite steel tubing according to claim 6, wherein the sum of the wall thicknesses of the two tubing sections provided exceeds 0.340 inch.

11. The method of making a composite steel tubing according to claim 6, wherein one of the tubing sections provided has its mating surface scored prior to telescoping the tubing sections.

12. The method of making a composite steel tubing according to claim 6, wherein the outer diameter surface of the inner tubing section is scored prior to telescoping the tubing sections.

13. The method of making a composite steel tubing according to claim 6, wherein the inner diameter surface of the outer tubing section is scored prior to telescoping the tubing sections.

14. The method of making a composite steel tubing comprising the steps of:

a. Providing two sections of welded steel tubing of substantially equivalent wall thickness, one of which sections has an outer diameter less than the inner diameter of the other;

b. telescoping saidtubing sections and locking them together at one end;

0. changing the diameter of one of said tubing sections so as to produce a mechanical bond therebetween; and

d. cold drawing the united tubing sections through a a mandrel.

sizing die and over

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1441459 *Feb 4, 1921Jan 9, 1923Philadelphia Bronze Bearing &Composite tube and method of making the same
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3990330 *May 8, 1975Nov 9, 1976Youngstown Sheet And Tube CompanyMethod of producing seamless tube mill piercer mandrel
US4125924 *Apr 4, 1977Nov 21, 1978United States Steel CorporationMethod of producing composite metal pipe
US4470188 *Aug 31, 1982Sep 11, 1984The Babcock & Wilcox CompanyMethod of mechanically prestressing a tubular apparatus
US4558721 *Jul 3, 1984Dec 17, 1985Apx Group Inc.Double walled tubing
US4759111 *Aug 27, 1987Jul 26, 1988Ti Automotive Division Of Ti Canada Inc.Method of forming reinforced box-selection frame members
US4784311 *Jul 11, 1986Nov 15, 1988Usui Kokusai Sangyo Kabushiki KaishaFuel injection tube for diesel engines
US5903967 *Jul 10, 1997May 18, 1999Mitsuba CorporationDouble cylinder body and a manufacturing method thereof
US6536806 *Mar 31, 1997Mar 25, 2003Usui Kokusai Sangyo Kaisha LimitedHigh pressure fuel injection pipe
US7243409Aug 5, 2003Jul 17, 2007Lewis John KWeldable conduit method of forming
US7921590 *Jul 18, 2007Apr 12, 2011Strum, Ruger & Company, Inc.Composite firearm barrel reinforcement
US8316568Mar 17, 2011Nov 27, 2012Sturm, Ruger & Company, Inc.Composite firearm barrel reinforcement
US8640740Aug 1, 2006Feb 4, 2014Afl Telecommunications LlcEmbedded metallic tubes with compression fit and method for manufacturing the same
US20100307720 *Aug 28, 2009Dec 9, 2010Furui Precise Component (Kunshan) Co., Ltd.Heat pipe
CN100491625CMar 30, 2007May 27, 2009葛心民Bimetal metallurgy combined high precision roller components and manufacturing method thereof
DE3920600A1 *Jun 23, 1989Jan 10, 1991Audi AgDouble walled pipe with insulating layer - is used as vehicle exhaust pipe and has pin for bending it into shape
DE102007011868B3 *Mar 7, 2007Sep 4, 2008Mannesmann Präzisrohr GmbHFuel-tube method for producing a high-pressure storage tube as a composite tube up to pressures of 1,800 bar operates with fuel injection in common-rail systems in internal combustion engines
EP0445904A2 *Mar 8, 1991Sep 11, 1991MANNESMANN AktiengesellschaftMethod of manufacturing a thick-walled high-pressure metal tube
WO1997034101A1 *Mar 11, 1997Sep 18, 1997Coflexip Stena Offshore LtdImprovements in or relating to bi-metal lined pipe
WO2005008116A2 *Jul 8, 2004Jan 27, 2005John K LewisSystem and method for coupling conduit
Classifications
U.S. Classification29/516, 29/523, 138/151, 29/520
International ClassificationB21C37/15
Cooperative ClassificationB21C37/154
European ClassificationB21C37/15D