US2940502A

US2940502A - Method and apparatus for deep beading thin gauge metal

Info

Publication number: US2940502A
Application number: US479405A
Authority: US
Inventors: Martine Francis N La
Original assignee: Chance Vought Aircraft Inc
Current assignee: Chance Vought Aircraft Inc
Priority date: 1955-01-03
Filing date: 1955-01-03
Publication date: 1960-06-14
Anticipated expiration: 1977-06-14

Description

June 14, 1960 F. N. LA MARTINEZ I 2, 2

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3, 1955 4 Sheets -Sheet 1 FIG 3 mm) i J n 1 1950 F. N. LA MARTINE 2,940,502

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3, 1955 4 Sheets-Sheet 2 INVENTOR.

Francis N. LuMuriine BY a yam June 14, 1960 F. N. LA MARTINE 2,940,502

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3, 1955 I 4 Sheets-Sheet 3 Francis N. LuMorfine BY WKM June 14, 1960- F. N. LA MARTINE 2, 2

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3, 1955 4 Sheets-Sheet 4 FIG.

FIG. 12 2O INVENTOR.

FIG- 4 Francis N. LoMurflne United States Patent IVIETHOD AND APPARATUS FOR DEEP READING THIN GAUGE METAL Francis N. La Mai-tine, Irving, Tex., assignor to Chance Vought Aircraft, Incorporated, Dallas, Tex., a corporation of Delaware Filed Jan. 3, 1955, Ser. No. 479,405

11 Claims. (Cl. 153-73) The present invention relates to the stiffening by beading and corrugating of closed uniform sections of thin material. It relates to. the use of an integral rolled bead. More specifically, this invention pertains to the circular, deep draw roll forming of a bead stifiened section of thin gauge metal.

The disclosed invention is particularly adaptable for the stiifening of thin metal sections of various forms. While 1 illustrate only uniform cylindrical shape sections, obviously closed sections of elliptical, kidneyshaped, or other irregular shapes are formable. My invention is particularly suitable for use in structures where weight control is a very critical factor, as in various vehicles, including aircraft for example. From the disclosed apparatus and new method of forming deep beads in the thin gauge metal, thinner, lighter, and higher heat resistant metals as titanium may now be successfully used to greater advantage, as in the shrouds for jet engine afterburners for example, Where weight saving materials are highly desirable.

I disclose further a new device and new method for stiffening a cylinder or any closed section of material without the addition of weight and without the cost being made prohibitive.

Briefly, the mechanism for the deep drawing of annular reinforcing beads in thin gauge metal, shaped into cylinders for example, consists of two pairs of special, concentric hoops and a pair of cooperating male and female rolls closely positioned between each pair of hoops. As the head is formed or rolled in the material between the two pairs of hoops, the material necessary for the bead is drawn from between one pair of hoops or the other, or from between both pairs to provide accurate control of the forming and positioning of the stifi'ening bead.

The principal object of this invention is to produce a means for stifiening thin gauge metal sections.

Another object of this invention is to form a simple, light weight, durable, and inexpensive to manufacture stiffened section of metal.

A still further object of this invention is to stiifen closed sections of thin metal, as stainless steel or titanium, by forming deep beads in the peripheral wall surface of the sections.

Another object of this invention is to provide greater accuracy in the forming and positioning of deep beads or corrugations in the peripheral wall surfaces of thin metal sections.

Another object of this invention is to provide a successful method for forming deep beads in thin sheets of titanium metal.

Another object of this invention is to provide a separate beaded stilfener that may be applied directly to the shell to be rigidified.

Other objects and advantages of the invention will be apparent from the following detailed description, together .with the accompanying drawings, submitted for purposes 2,940,502 Patented June 14, 1960.

ice

of illustration only and not. intended to define theLsQOpe; of the invention, reference being had for thatpurpose to the subjoined claims.

Brief description of figures Fig. 1 is a perspective view of a section or cylinder of very thin metal that has been stiffened by the. forming, of deep beads therein;

Fig. 2 is a perspective view of a section or cylinder of very thin metal illustrating, by the weakness of the material and the form it assumes before it has been.- stiffened, how thin the metal may be and yet can be successfully headed by the disclosed method;

Fig. 3 is a perspective view of the pair of matching female and male rolls in position for. the forming ofinternal beads;

Pig. 4 is a perspective view of the rolls of Fig. 3. when forming an internal head in a section of material;

Fig. 5 is a plan view of the portion of the internal hoop with the latch mechanism;

Fig. 6 is a side view, with parts in section, of the internal hoop latch mechanism locked in extended. posi-. tion;

Fig. 7 is: a side view, with parts in section, of the iiiternal hoop latch mechanism in extended position, butunlocked; V

Fig. 8 is a side view, with parts in section, of the ilkternal hoop latch mechanism. as it is moving toward col; lapsed position;

Fig. 9 is a side view, with partsin section of the in-. ternal hoop latch mechanism locked in collapsedposition',

Fig. 10 is a perspective view of both the internal and external hoops in position for clamping-the material to be beaded;

Fig. ll is an enlarged vertical sectional view of the mechanism wherein the solidline position illustrates. a portion of the rolls, hoops, and section of thin material, prior to the forming of the external bead and th dotted line position showing partial penetration of the upper roll by the lower roll;

Fig. 12 is an enlarged vertical sectional view of a POI! tion of the rolls and section of thin material after the forming of a complete external bead;

Fig. 13 is a perspective view similar to Fig. 4, but with the rolls reversed in position to form an external bead in the section of material; and

Fig. 14 is a perspectivev view of a stiffener. used as'an alternative means of reinforcing a thin gauge cylindrical section.

Detailed description of apparatus for forming deep beads in thin gauge metal Stifier and lighter closed sections of thin metal are desired and required in vehicles oftoday, particularly in aircraft. This invention is very adaptable to the forming of a stifier and lighter shroud wrapper of titanium or the like metal for a jet engine or the afterburner therefor, wherein the forming of deep beads is diflicult due to excessive elongation with resulting reduction of thickness, excessive wrinkling, tensile failure, cracks along the axis of the bead, work hardening, or excessive springback.

Referring to the drawings, shell 20 is. a closed section of very thin material to be stiffened and rigidified as illustrated in Fig. 2 in the shape or form it assumes before it has been stiffened, and the shell is shown in Fig. 1 after it has. been stiifened with deep drawn beads or

grooves

21 and 22.

The mechanism for deep drawing the grooves consists of male and female bead forming drive rolls 30 and 151, respectively, one of the rolls being closely spaced between two internal work-engaging hoops or draw rings 40 and various positions it may assume. This latch mechanism comprises a linkage system with provisions for contraction and expansion'of the hoop, and with provisions for locking of the hoop in either the contracted or expanded positions. Furthermore, a'fine adjustment of elongation of the hoop may be effected to insure proper fitting between the hoop and the cylinder of material as will be described hereinafter.

'Inte rnal split hoop 40 is formed circular from an elongated channel member with the base of the channel forming the outer peripheral surface of the hoop. The

two contiguous split channel hoop ends 42 and 43 of hoop 40 are beveled as shown in Figs. 6-9 forease of collapsibility and are interconnected'through a linkage system. Welded near one end, 42, of the hoop and within the channelis a block with a socket headed; oval point set screw 45 threaded therethrough. The portion of the set screw with the oval point projecting through block 44 has a reduced neck portion near the'pointed end. A yoke 46, slideable in the split channel end 42 is adapted to receive the above-mentioned portion of the set' screw. This latter portion of the set screw is freely rotatable in yoke 46 and, as illustrated in Figs. 5 and 6, I

is maintained therein with pin 47 in yoke 46 normal to the set screw and contiguous with the reduced neck portion. Yoke 46, being 'slideable in the channel hoop, accordingly projects from the end 42 thereof to provide an adjustable extension of the channel end. The other end of set screw 45 is provided with a socket for rotation of the screw and the resultant slideable movement of yoke 46 varies theeffec tive length of the channel end.

42; Because set screw 45 is actuatedin only one straight, axial directionas it screws through block 44 and as the yoke 46 slides in an arcuate path in the channel hoop, the pointed end of the set screw is oval shaped to' prevent binding between the set screw and the yoke. Accordingly, a fine adjustment of elongation of the hoop may be effected to provide. an adequate and proper fitting of the internal split hoop, 40 or 41, inside thecylinder material. Pivotally connected to slideable yoke 46 is one link 48 of the two pivotally interconnected scissor links, 48, 49. 'The other link 49 of said pivotally intercon nected scissor links is pivotally connected to a pair of :hlocks indicated at 50.; .The blocks 50 are welded in the manner the other end 43 of the hoop, but spaced from the tip of the end approximately the length of the two scissor links when collinear with each other, Fig. 6 or 7. With theends-of the internal hoop connected together through pivotally connected links, the dimension of the circumference and accordingly the diameter of the hoop may be varied by moving one end of the hoop, left end 42 of Fig. 7 or 8, up and inside or overlying the other hoop end 43 to facilitate accurate positioning of the internal hoop in the section or cylinder of material to be headed. The internal hoop may be unfolded to expanded position, as shown in Fig. 7, to grip the shell 20, or the hoop may be folded to collapsed position, Figs. 8 and 9 to permit its ease of adjustment, positioning, or removal from the cylinder. g p

' The

internal split hoops

40 and 41 are each provided with a lock screw 51, Figs. 6-9, to maintainthe hoop-in either of the two extreme positions, the extended or expanded position and the contracted or collapsed position. Lock screw 51 is detachably secured in link 48 with pins 52. A projecting end of the lock screw cooperates with "a threaded aperture in juxtapositioned rest pad or lock screw stop nut 53A which is "welded in the channel hoop to lock the scissor links in collinear or open position. After the hoop is extended-to the expanded position of Fig. 7, it is then looked in'the expanded position with lock screw 51 as illustrated in Fig. 6. In the other scissor link 49 is forni'ed a stop nut or rest pad 53B with a threaded opening to accommodatelock screw 51. Accordingly, the collapsed hoop of Fig. 8 may be locked and maintained in contractedposition ,by the co operation between lock .screw 51 and stop nut 5313, as illustrated in Fig. 9.

. Rollers 54, Figs. 5 and 6, with spacing washers 56 are journaled on studs55 which are secured at the right end 43 of the internal channel hoop or annulus. Rollers 54 are so positionedon the edge of hoop channel end 43 that hoop end 42 abuts the rollers and rides up and on them when the hoop is contracted andthe hoop end 42 is moved to overlapped position with hoop end 43, Fig. 8 or 9. Rollers 54 accordingly provide an antifriction device for facilitating collapsibility of the hoop and its latch mechanism when unlocked.

- A second pair of external Work-engaging

hoops

60, 61 are utilized in conjunction with the

internal hoops

40, 41, respectively, in that each of the external hoops surrounds its respective internal hoop so that each of

external hoops

60 and 61 is concentric with

hoops

40 and 41, respectively, with cylinder 20 positioned between the external and internal hoops, noting Figs. 10 and 13 particularly. .As seen in Figs. 10 and 13, I utilize an adjustable swivel bolt 62 and yoke. 63, or the like, type of adjustable clamping means connecting the ends of a steel band forming each of the

external hoops

60 and 61. This adjustable clamping device is utilized to tighten the external hoops around the-cylinder to be beaded to provide additional clamping action to that of the internal hoopsof the material of shell '20 and to prevent wrinkling when forming the external beads. Accordingly, in the forming .of external beads,

externalhoops

60, 61 provide additional control of how 'of material over

internal hoops

40, 41.

From the above description, the lightness inweight, high strength and simplicity of construction, and ease'of manipulation of both internal and external draw rings or hoops are featuresofi particular consequence.

Male and female rolls 30'and '31, Fig. '3, are utilized to form the

beads

21 or 22 in a sectionofcylinder 20; a detail description of the rolls, per 'se, is as follows: Y

Male roll 30, Figs. 11 and 12, has a rib 32 centered in the peripheral cylindrical surface thereof. While ribs of various shapes and depth have been tried, depending on the degree of'rigidity desired to be imparted to the section of material 20, I- have found substantially semicylindrical ribs to be preferable. Accordingly, rib 32 on the male roll 30 is circular over'the crest thereof with the sides of the circular crest smoothly contoured to shoulders 33 through fillets 36. The shoulders 33' of male roll 30 must, of necessity, slope downward-as viewed in Figs. 11 and 12, depending on the hardness of the material to be headed. In the 'rolling'of titanium for example, this slope is required to be approximately 8 degrees below the horizon to provide for springback, whereas only a slope of 6 degrees is required for springback in stainless steel.

Female roll 31, of the same diameter and width as 'male roll 30, has a groove 34 centered in the peripheral cylindrical surface thereof and sloped shoulders 35 contoured to the groove through fillet 37 to provide a substantially contiguous surface with the peripheral cylindrical surface of the male roll 30. However, when the two

rolls

30 and 31 are in juxtaposition with each other,

'as when rolling a head 21, Fig. 12, most of the parts of the peripheral surfaces of the two rolls are not exactly equidistant from each other. This is to prevent flattening, thinning, marring and scratching, and weakening of the material in the bead. Only the surfaces of the fillets 36- of the male roll rib32 are equidistant from; the surface of the fillets 37' of: the female roll' 31 As shown: in Figs. ll and 1-2, the slope of the female roll shoulders 35 is approximately 6 degrees below the horizon to provide for springback when rolling titanium, for example.

Due t'othe above described slopes of the-shoulders. 33 and 35 of the male and female rolls, respectively, the: distance between the shoulders of the rolls, Figs. 11 and I2 gradually increases from the fillet outward to the edge of the roll. Also, the radius of curvature of the groove 34 is greater than the radius of curvature of the crest of rib 32 to provide for the distance between the surfaces of the rib 32 on the male roll 30 and the groove 34, on the female roll 31 to increase from the

fillets

36, 37 of the two rolls inwardly to the center of the crest of the rib 32 or the center of the groove 34. Accordingly, no coining action and thinning of the material over the crest of the rib 32 nor over the shoulders 33 of the male roll will result during the rolling operation.

Method of forming deep beads in thin gauge metal Broadly, the external head 21 is rolled in the shell 20 with the two pairs of hoops or draw rings, and 60, and- 41 and 61, positioned each in contiguity with the sides 38, '39 of the rolls 3% and 31-. With the rings so placed, the amount of material flow therebetween each pair of hoops iscontrolled so that it can be drawn from either end of the shell or both.

While various methods may be utilized in the practice of this invention, the preferred method of using the disclosed hoops and rolls and of forming a deep bead or beads in thin gauge metal comprises positioning the two internal draw hoops, 40 and 41, in collapsed condition, Fig. 9, internally of one end of the shell 20, both hoops equally spaced on each side of the proposed position of the bead in the shell. The

internal draw hoops

40, 41 are so spaced that internally positioned male roll 30 fits snugly therebetween when rolling the bead 2.1 in the shell, whereby both sides 38 of the roll 31 are in contiguous relationship with the internal hoops. The internal hoop, 40, nearest the finished end of the shell is expanded, Pig. 6, to a predetermined compression until the friction between the hoop and the inner surface of the shell is great enough to prevent any relative movement be tween the shell and the hoop. The other internal draw hoop, 41 is expanded against the inner surface of shell 20 until it is firmly held therein. Then to provide additional control of material flow and to prevent wrinkles when forming the external bead, expanded external hoops 6i? and 61 are circurnpositioned externally of the cylinder ZG'directly opposite or on the other side of the shell material from the internal hoops .0 and 41, respectively, Fig. 13. External hoop 60 is contracted to a predetermined tension until the friction between the hoop and the outer surface of the shell is great enough to prevent any relative movement between the shell and the hoop. The other external hoop 61 is contracted against the outer surface of shell 20 until it is firmly maintained therearound. Then the male roll 39 is inserted in the shell between the internal draw hoops 4t), 41, and the female roll 31 is positioned externally of the shell directly 0pposite to and in coplanarity with the other roll 30 and snugly fitted between exterior hoops 66 and 61 and in contact with the outer surface of the shell, as illustrated in Figs. lll3. With the hoops so positioned on the shell 26 and contiguous with the rolls, the external head 21 is rolled, Fig. 13. During the rolling operation, material is drawn from the cylinder 26 overall length and flows over the internal draw hoop 41 and under the external hoop 61. This flow of material is controlled byvarying the tension in the material as it flows between the internal and

external hoops

41 and 61, in forming the sad. The tension in the material as it is rolled. is controlled by the radial force between the hoopsand the sheil' material, which force is effected by circumferential 6 adjustment of the hoops. Proper control of the tension further prevents wrinkling and cracking of thevbead.

Ex ternalhoops

60, 61 likewise perform the function. ofpreventing wrinkling of the cylinder.

When the cylinder is rotated about its axis by contact between the bead forming rotating drive rolls 30 and 31 in forming an external bead 21, the innermost end faces of the draw hoops 4t), 41 are in contact with the sides: 38 of male roll 30. As pressure on the male roll 30 is increased outwardly, Fig. 11, towards the female roll. 31, the material is rolled into the female roll. groove 34with the correct predetermined tension. 7 I

The diameter of each

draw hoop

40, 41 and

hoops

60, 61 is adjustable (within limits) wherein the radial hoop pressure against the cylinder by both external and internal hoops may be adjusted for controlling the friction between the hoops and the shell or cylinder. Thus, control is provided of the amount of material or axial flow of material drawn through the hoops, Fig. 13. Accordingly, in the forming of a single stiffening bead for example, the material for the bead may be supplied from one side, or the other, or both. Therefore, very accurate control of the how of material from either side of the rolls for forming a head is maintained. This accuracy is carried through in the forming of bellows for example. In this operation, the past methods involve spacing each pair of head or corrugation forming rolls from the last succeeding. bead formed, as disclosed by Fulton, U.S. 947,229. Accordingly, any deviation or inaccuracy made in one bead or in the spacing between two beads of the bellows is carried on or additive thereto throughout the. whole operation. In the present invention, the rolls may bev positioned at an exact particular distance from the finished end. of the bellows and the next succeeding head. or corrugation formed by feeding the material for the bead from the unbeaded end of the bellows. Therefore, the inaccuracies of each head made is not accumulative throughout the bellows as is true in former methods of forming a multiplicity of beads or corrugations.

The above method of using the disclosed apparatus for deep beading hard metal as titanium is the best and most economical method found. The principal reason for the success of the disclosed method of forming hard metals over other methods as drop hammering, stamping, etc., is deemed to lie in the fact that impact shock, which is unavoidable, inherently causes failures in the metals formed by the prior methods. This method wholly alleviates impact shock material failure, as plastic flow qualities of low-ductility material are encouraged. The material for forming the beaded cylinder is placed between the forming rolls with the grain of the material parallel to the axes of rotation of the formingv rolls, i.e., the bead longitudinal circular axis will be normal or transverse to the grain. As the material passes between the forming rolls, greatest plastic flow results. with the grain, or in the direction of force applied, and accordingly the grain of the cylinder material lies parallel to the longitudinal axis of the cylinder formed. The plastic flow of the metal is also augmented by relaxation during the forming cycle which prevents fatigue failure of the metal. This flow and relaxation during the forming cycle is indigenous only to this process. Plastic flow of the metal is initiated by the combined action of the rollers and draw rings. Tension forces on the metal 20 as it is drawn from the length of the cylinder being rolled produces compression and tension stresses within the metal material thickness at the points of tangency of the forming rolls 30 and 31 as the roll center-to-center distance decreases in the bead forming operation. In the first part of the rolling op.- eration, Fig. 11, the portion of the shell material 20 between the surface contiguous with the female roll fillet 37 and the neutral bend line of the material is caused to be in compression and the portion of the shell material between: the neutral bend line and the other surface of the material is caused to be in tension. Likewise, the portion other surface of the material is caused to be in tension. Tension is exerted 'across'the full thickness of the shell material 20. between the above described areas. .In the latter part of the rolling operation, Fig. 12, wvith the .of the male roll and is placed in tension, while the portion of the shell material between the neutral bend line and the other surface of the material that was in tension has likewise now moved up to overlie male rib 32 and is placed in'compression. If all material is drawn solely from one side of the roll to form the beads 21 M22, further plastic flow and reversal of stresses is evidenced in that portion of theshell material 20 formerly over the circular surface of the male rib 32 and which eventually overlies the reversed curved fillet 36 of the male roll 30; This plastic fiow is finally arrested within the material thickuesswhen the rolls and material attain 100% bearing through. their entire profile section. Coining of the material'between the

fillets

36 and 37 of the'female and male rolls, respectively, then stops plastic flow and minimizes springback. During each revolution of rolling,

as the material is gradually formed between the rolls, all material in the metal shell being formed that is not in contact with the rolls is in a state'of relaxation. This cycle of forming utilizing plastic flow and relaxation withinthe metal results in maximum forrnability' and minimum failures. 7

Internal beads 22.of unusual proportions of width to depth can also be formed in very thin gauge materials from round, elliptical, and other curved cylindrical'or conical shells 20 by reversing the positions of male and

female rolls

30 and 31, respectively, as disclosed in Fig. Dueto the low percentage of elongation, this process has 'proven highly successful for cold forming of titanium that otherwise would Workharden and crack.

ln theforming of the internal beads 22, the

external hoops

60, 61 may be omitted. Accordingly, during the rolling operation, the material for the bead is drawn from the shelloverall length and flows over either one or both circumferentially adjustable hoops or draw rings, 40, 41. In the forming of the internal beads 22, wherein the-

internal hoops

40 and 41 are .position ed contiguous with the sides 39 of the female role 31, the radial force opposing the tension of the material flow toward the center of the bead is controlled solely by the circumferential. adjustment and release lock mechanism of the in ternal draw rings 40,- 41 described above.

7 Modification In place of heading the jet engine shroud or shell 20, per se, a separate stiffener may be formed and attached as by 'riveting, spot welding, or the like, to the shell. This stiifener is formed from a thin strip of metal bent in a circle. While a single stiffener may consist of one ormore attached curved or arcuate strips, I prefer and illustrate, Fig. 14, one formed from two curved strips or halves, 70 and 71 joined together to provide one circular or endless stiffener stn'p. With the adjacent ends of the strips maintained overlapped with each other, a head 72 is rolled between the edges of the strips for the full length thereof. Accordingly, simultaneously with the rolling of the head in the full length of the stiffener strip, the overlapped edges are headed and formed into 'material'is caus'ed tobe;'in compression and the portion of the shell material between neutral bend line and the described hereinbefore areutilized', a different and more simple internal hoop may be utilized. This internal hoop may be a solid ,unadjusta'ble ring, as its diameter controls of sets the inside diameter of the finished stiifener. With the use of the constant diameter internal hoops, the control of material flow is provided solely from the external hoops. Another feature in forming the bead in the stiffener comprises the rolling of the'bead with the grain of the material normal to the longitudinal circular axisof the bead. Therefore when the head is across the grain, beads of various shapes and depths can be produced without the danger of cracking.

Either internal or external beads 72 may be formed in the

stiffener

70, 71, as in the foregoing description in the forming of the

beads

21 or 22 in shell 20. Accordingly, a

beaded stiffener

70, 71 is provided that is equally adaptable as a reinforcing member mounted on either the inside or outside diameter of the shell 20.

While only shells, i.e., cylinders or conical sections, of metal are described in the instant disclosure, obviously shells of other materials may be beaded.

It will be obvious to those skilled in the art thatvarious changes may be made in the invention without departing from the, spirit and scope thereof and therefore the invention is not limited by that which is shown in the drawings and described in the specificatiombut only as indicated in the appended claims.

. I claim: r

1. A method of rolling a deep head in a cylinder of thin gauge metal with internal and external forming rolls and a pair of circumferentially adjustable work-em gaging draw rings, the walls of said cylinder having inner and outer surfacesrand each of said rolls having sides comprising, positioning said'rolls on opposite sides ofthe cylinder walls for rolling the beads therein be tween the rolls, positioning one of said circumferentially adjustable work-engaging draw rings in contactwith one side of one of said rolls andin contact with one wall surface of the cylinder, positioning the other circumferentially adjustable work-engaging draw rings in contact with the other side of said one roll and in contact with said one wall surface of the cylinder, and varying the lengths of both of said adjustable work-engaging draw rings for controlling the friction between both said adjustable workengaging draw rings and said cylinder one wall surface for flow control of the cylinder material to said head.

2. A method as set forth in claim 1 comprising, positioning a second pair of circumferentially adjustable work-engaging draw rings in contact with the other wall surface of said cylinder and in contact with both sides of said other roll, and varying the lengths of said second pair of said circumferentially work-engaging draw rings to provide additional flow control of the cylinder material to said bead.

, 3. A method of rolling a deep bead as set forth in claim =1 wherein the grain of said cylinder material lies parallel to the longitudinal axis of the cylinder, said first step comprises the positioning of said rolls on opposite sides of said cylinder with the grain ofthe cylinder material lying normal to the longitudinal circular axis of the head to prevent cracking thereof.

4. A method of rolling a deep head in a shell of thin gauge metal with internal and external forming rolls for a joggle joint. 'This joggle obviates the necessity of '15 gaging means incontact with the other said shell walls,

E7 varying the radial pressure of at least one of said means to control axial flow of the material past both of said means, and rolling said bead with both said means contiguous with the opposite sides of one of said rolls.

5. A method as set forth in claim 4 wherein the bead stifiened shell is an endless stiffener comprising a plurality of arcuate strips placed end-to-end with their adjacent ends overlapped, and wherein the rolling step comprises further rolling of the bead in said overlapped ends of the strips to form joggle joints in said bead stiffened stiffener.

6. In the stifiening of a shell of thin gauge metal by rolling a bead in the peripheral surface thereof between an internally positioned forming roll and an externally positioned forming roll, the method of controlling the axial flow of material for forming said head comprising, positioning circumferentially adjustable work-engaging hoop means internally of said shell in contact with the inner surface of the shell wall and contiguous with one side of one of said rolls, positioning a second hoop means internally of said shell and in contact with the inner surface of the shell wall and contiguous with the other surface of said one roll, and adjusting both of the hoop means to control the radial pressure and friction between both of said hoop means and said shell for control of axial fiow of the bead forming material past both of said hoop means.

7. An apparatus for deep draw roll forming of a head in a shell of thin gauge material comprising: a pair of mating rolls for rolling the bead therebetween, means in contact with one surface of the shell and in contact with a side of one of said rolls, second means in contact with said one surface of the shell and in contact with the other side of said one roll, both of said means being adjustable for controlling the axial flow of the material of the cylinder to the mating rolls whereby the rolls may form said deep bead.

8. An apparatus as recited in claim 7 including a set of two additional means, one of said additional means being in contact with the other surface of the shell and in contact with the side of the other roll, the other of said additional means being in contact with the other shell surface and in contact with the other side of said other roll, both of said additional means being adjustable for hearing against said other surface of said cylinder for varying the radial pressure and friction between both of said additional means and said cylinder for control of said axial flow of deep bead forming material.

9. An apparatus as recited in claim 7 wherein said means comprise circumferential adjustable work-engaging draw rings for acting against said one surface of said cylinder for varying the radial pressure and friction between said draw ring and said cylinder for control of said axial flow of deep bead forming material.

10. An apparatus as recited in claim 7 wherein each of said means is adjustable to an expanded position and to a contracted position, a releasable lock mechanism included in said means for locking same in contracted position for ease of locating said means in contact with a side of a roll and for locking same in extended position for fixing said means immovable relative to the shell.

11. An apparatus as recited in claim 7 wherein one of said means is an annulus, said annulus being split to provide two movable ends, one end being collapsible over the other end to provide contractability of said annulus, and each of said ends including rollers mounted thereon to facilitate contractability of said annulus.

References Cited in the file of this patent UNITED STATES PATENTS 680,442 Schrnitt Aug. 13, 1901 971,838 Fulton Oct. 4, 1910 975,519 Fulton Nov. 15, 1910 J1,330,804 Haskell Feb. 17, 1920 1,451,998 Neubauer Apr. 17, 1923 2,239,696 Bohm Apr. 29, 1941 2,468,488 Coyle Apr. 26, 1949 2,712,340 Sandberg July 5, 195,5