US2170811A - Method of forming cold-worked articles - Google Patents

Description

Aug. 29, 1939. E. s. COI QNELL. JR 2,170,311

METHOD OF FORMING CQLD'WQRKED ARTICLES Filed July 15, 1937 T a- T5 Tifii.

. I mm 25 Ill! 22 INVENTOR Ed d S. ornelLJ.

-OK HI TORNEY Patented Aug. 29, 1939 UNITED STATES PATENT OFFICE METHOD or FORMING COLD-WORKED ARTICLES Application July 15, 1937, Serial No. 153,728

3 Claims.

The invention relates to an improved method general configuration of the fitting, and additionof forming hollow objects.

More particularly, the invention relates to'the forming of tubular fittings or other hollow ob- 5 jects from amass of predetermined cubical content and desirably also of predetermined configuration, from metallic compositions of relatively soft, and/or ductile constituency; whereby under cold fiow of the material of such mass into the desired hollow configuration internally and externally, the material at final worked status of the fitting or the like possesses the requisite tensile strength, compressional strength and flexural strength. 7 h

Advantageously, the process is carried out by the.employment of the original mass material in the form of a wire, bar or the like, having a cross section facilitating the attainment of a desired outer configuration in the final product, and severing therefrom individual masses of predetermined cubical content.

A feature of the inventiommore particularly directed to imparting hollowness to the object, comprises subjecting a mass of predetermined 25 cluding displacing the central-core of the mass by a suitable male die member; thereby bringing about cold flow of thethus displaced central core portion, and increasing the dimension of the resulting worked mass in the direction of working. 1

Pursuant to the preferred procedure in carrying out the invention,- perforation of the worked mass, necessary to the function ofthe desired 35 fitting as a fluid-passing device, is accomplished by carrying out the cold-flow displacement of the central core of the worked mass to the extent of the full length of bore of the desired fitting, but providing for a veil of solid material 4 at the terminus of the full stroke of the male die member, whereby upon severing such veil portion from the worked mass. a tubular fitting of desired length of bore is obtained.

A possible and preferable characteristic of fit 45 tings resulting fromthe invention, resides in the formation by cold flow, similar as above, of relatively thickened mass portions, having a polygonal outer configuration adapted to be engaged by a wrench or like tool, for installing the fitting. A distinct advantage of the invention resides in the production of fittings substantially wholly by punch and die operation, thus eliminating such usual machine operations as milling or drilling. which involve removal, and consequent great waste, of material in providing for the bore and cubical content to suitable die operations, in-

ally incur high cost of labor, equipment and expense of equipment operation. Further, pursuant to conventional practice, material subjected to milling or similar machine operations is prefer- 5 ably of relatively soft, or easily machinable stock, the physical properties of which remain substantially unchanged by the machining operations. In contrast, the densified grain structure of the product embodying my invention is char- 10 acteristic of a metal work-hardened to a degree approaching a maximum.

The invention is applicable to fittings of the usual threaded type as well as of the compression and other types. To provide threading for a 16 threaded fitting, accepted machine operations are advantageously employed.

Illustrative of copper-containing metallic material which has been successfully employed pursuant to the invention in the production of 20' Copper per cent 61 to 66' Zins do 37.5 to. 34 Lead per cent and less 1.5

The proportion of lead is preferably as low as possible, optimum cold flow or cold forging results being obtained when the worked material has minimum lead content.

In brief, my inventlon'is directed to the formation of hollow or tubular metal objects by subjecting amass or slug of metal, of predetermined cubical content closely approximating the cubical content of the finished product, to processes involving a minimum of operations other than cold-workingby punch and die; to the end that the desired configuration of the oli- 4 ject will be obtained with a minimum of waste of. metal; that subsequent operations addressed to imparting a desired finish or appearance Wlll be minimized; and that certain physical properties of the metal of the slug will be improved by the refinement and compacting of the metallic grain structure through the cold working process.

Further features and objects of the invention will be more fully understood fromthe follow- 1 ing detail description and the accompanying drawing, in which Fig. 1 and Fig. 2 are side and plan views of a mass of material of predetermined cubical tontent and predetermined configuration, in this instance cylindrical;

Figs. 3 and 4 are elevation and bottom plan views of a stage of cold working of the mass shown in Figs. 1 and 2, this stage including the formation of a partially hollow interior, with increase of longitudinal dimension and frustoconical bottom configuration;

Figs. 5 and 6 respectively show a side elevation, partially broken away in vertical section, and a bottom plan view of a stage subsequent to that of Figs. 3 and 4. Figs. 5 and 6 show an increase of transverse dimension and formation of non-cylindrical contour, in this instance at the top;

Figs. 7 and 8 are respectively side elevation, partly broken away in vertical section at the bottom, and bottom plan view at a stage subsequent to the stage of Figs. 5 and 6. Figs. 7 and 8 show in particular an increase of the length of the hollow interior, as compared with the showing of Figs. 5 and 6;

Fig. 9 is an exploded view in side elevation, indicating the severing of the bottom veil portion,

to afford a full-bore passage through the coldworked mass; I I

Fig. 10 is a bottom plan view of the upper part shown in Fig. 9; and

Figs. 11 and 12 are respectively a side elevation, partly broken away in vertical section and a bottom plan view at a stage subsequent to that of Figs. 9 and 10, the subsequent stage having included a thread-cutting operation.

Referring to the accompanying drawing, lllustrating a preferred procedure of producing, pursuant to my invention, an interiorly hollow product:

The particular hollow interior product 20 derived pursuant to my invention, shown in Fig. 11 in elevation, partly cut away in vertical section, and in Fig. 12 in bottom plan view, is a conventional screw-threaded, tubular fitting. Figs. 1 and 2 show in elevation and pla ,view a slug or mass 2| of predetermined cubi a1 content and predetermined configuration, -from which a product such as that shown in Figs. 11 and 12, is produced, pursuant to my invention. Figs. 3 through 10 show stages intermediate the' final stage, represented by Figs. 11 and 12. As appears generally from the showings of Figs. 1 through 12, inclusive, an advantage is gained by employing an initial slug 2| having an outer configuration conforming generally to that of the final product 20, in this instance an outer con- 1 tion of number of stages of treatment and min imum waste.

- The slug 2| may advantageously be formed by severing, from a billet, rod, wire or the like, a

mass having a predetermined cubical content as required by the worked object at an intermediate stage, later described, and closely approximating the cubical content of the final object. The slug 2| is preferably a compact, unflexing mass of relatively soft and/or ductile material, capable of attaining, under cold working, a dense granular structure, and resulting enhanced physical properties such as'tensile strength, compressional strength and fiexnral strength. I have found the previously described alloy to be suitable for general purposes, but it will be understood that my process is not restricted to the use-of such alloy.

Steps in the formation of the product 20 include subjecting the slug 2|, at substantially atmospheric temperatures, to suitable die operations or similar cold working methods inducing cold flow of the metal. Preferably such operations are accomplished in apparatus as described in my copending application Serial #64:,722, filed February 19, 1936, entitledMachine for forming /cold wrought products.

Advantageously the operations include confining the slug 2| within a die, one surface of the slug being exposed, and subjecting the central portion or core of the slug to a male die operation in which the pressure of fluidity of the metal of the slug is attained; thereby inducing cold flow of the central core, causing an elongation in the direction of working, and forming a cup 22, see Fig. 3, having a central bore 23 and a comparatively heavy-walled base portion 24. The outer configuration of both the side wall 22a of the cup and of the base portion 24 may be as desired. .In the embodiment shown, the outer shape of the cup is cylindrical, and that of the base portion is frusto-conical. It is preferable that at this stage, the base portion 24 be sufliciently heavy to support the cup 22 without rupture or unwanted deformation at the base, during additional sidewall shaping operations.

In forming a thickened portion or collar 25,

shown in Fig. 5 as having a polygonal or noncylindrical configuration and adaptable thereby to accommodate a wrench or suitable tool in the ultimate application of the fitting, the cup 22 is subjected to additional die operation or operations, causing cold fiow of a portion of the metal of the side wall 22a into the desired configuration, and correspondingly reducing the overall length of the cup 22. The collar 25 may in this manner be given its ultimate shape, thus eliminating subsequent finishing operations. It .is to be noted that except for the formation of the collar 25 the wall of the cup 22 may remain unchanged as to thickness, -'and also, from a comparison of Figures 3 and 5, that the depth of penetration of the bore 23 into the base portion remains unchanged.

The next stage shown in Figures 7 and 8 may involve the lengthening of the bore to the desired extent, the die operation proceeding to the point of, but not accomplishing, penetration of the blank, thereby simultaneously reducing the quantity of material in the base portion, and forming a comparatively thin-walled "veil", 24a, Fig. 7, ofpredetermined minimum cubical content and wall thickness, and readily severable from the body of the cup 22. The depth of the bore is now substantially as required in the finished,

tubular object, and by a process including severing the veil 24a, the ultimate shape of the object as a tubular fitting is attained.

It is a feature of this invention that finishing operations, that is, operations directed primarily to imparting a smooth or attractive finish to the object, are reduced to a minimum, in that the metal is caused, by cold flow integral movement, to conform to the shape of the die, and the walls and surfaces may thereby be formed free from such defects as burrs, .tool marks or the like, which subsequent finishing operations are usually required to eliminate. Cold flow of the metal, as distinguished from hot forging or similar processes carried on at elevated temperatures, minimizes the formation of metallic oxides.

The completed object 20, as shown in Figures 11 and 12 may include a male threaded or otherwise machined outer surface, for the purpose of imparting a. definite or predetermined utility to the object. Such machining may advantageously be accomplished by known machine operations.

1. The method of producing a tubular object having a non-circular formation at its periphery,

which comprises confining a' metallic mass within a female die, subjecting said mass, in cold state, to endwise pressure by a male die'having an outer diameter less than the inner diameter of the female die to flow metal of said mass from the central portion of said mass outwardly and upwardly between the walls of said male and female die, compressing said shell within a die to flow metal of said mass'later'ally of the walls of said shell to provide the said non-circular formation, applying endwise male die pressure to the base of said shell to flow metal of said shell upwardly between said male and female dies to elongate the wall of the object to substantially its ultimate length, and subsequently severing said base portion to provide a clear bore through said object.

2. The method of producing a tubular object having a non-circular formation at its periphery,

3 which comprises confining a metallic mass within a female die, subjecting said mass, in cold state,

to endwise pressure by a male die having an outer diameter less than the inner diameter 'of the central portion of said mass outwardly and upwardly between the walls of saidmale and female die, while conjointly elongating said mass to form a shell having a relatively heavy base, compressing said shell within a die to flow metal of said mass laterally ofthe walls of said shell to provide the said non-circular formation, applying endwise male die pressure to the base of said shell to flow metal of said base portion upwardly between said male and female dies to elongate the wall of the object to substantially its ultimate length, and subsequently severing said base portion to provide a clear bore through said object.

3. The method of producing a tubular object having a non-circular formation at its periphery, which comprises confining ametallic mass having a cubical content substantially equal to the cubicalcontent of the tubular object within a female die, subjecting said mass, in cold state, to endwise pressure by a male die having an outer diameter less than the inner diameter of the female die to flow metal of said mass from the central portion of said mass outwardly and upwardly between the walls of said male and female die while conjointing elongating said mass and forming a shell having a relatively heavy tapered base, compressing said shell within a die, while maintaining a constant shell bore diameter, to flow metal of said mass laterally of the walls of said shell to provide the said non-circular formation, applying endwise male die pressure to the base of said shell to reduce the thickness of the base thereof andto flow metal of said base portion upwardly between said male and femaledies to elongate the wall of the object to substantially its ultimate length, and subsequently severing said tapered base portion to provide a clear bore through said object. v

" EDWARD S. CQRNEIL, JR.

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