US967010A - Flexible corrugated-metal wall. - Google Patents

Description

W. M. FULTON. FLEXIBLE CORRUGATED METAL WALL.

APPLICATION FILED MAR. 4, 1907. v

Patented Aug. 9, 1910.

tions.

tit

on irnn s'rArrns PATENT OFFICE. WESTON in. FULTON, orqmoxvILLn, Tennessee, ASSIGNOR TO THE runrou oom- .PANY, or KNOXVILLE, rmmnssnn, A com-onnrrouor MAINE.

FLEXIBLE CORRUGATED-METAL WALL.

. Specification of Letters Patent:

Patented Aug. 9, 1910.

To all whom it may concern:

Be it known that I, its'roN M. FULTON,

of. Knoxville, Tennessee, have invented a,

new and useful Improvement in Flexible Corrugated-Metal Walls, which improves ,ment is fully set forth in the following specification.

This invention relates to vibratory corrugated metal walls, particularly of collaps ble and expansible vessels for confimn fluid under pressure, and to the method o making such walls, and it has for its primary object to provide a metal corrugated wall which is very thin and flexible, while securing at the same time strength and durability to a marked degree.

It is well known in the art of metal 'workally termed a grain in the metal. This grain is particularly noticeable in thinsheet metal, Whether rolled from a billet or in the form of a drawn tube. Metal having this grainis also known to have a greater tensile strength along the grain than across it; likewise resilience, durabilityand the co efficient of expansion of the metal are not the same along the grain as inother direc- Metal tubes made from drawn or rolled metal possess, therefore, this grain to a more or less marked degree, and its presence lends tensile strength to the tube 711 directions parallel to the grain. In the manufacture of flexible corrugated sheet metal walls for collapsible and expansible vessels as heretofore practiced, the grain of the metal which was lengthwise of the uncorrugated tube'retainsthis direction in the corrugated tube and therefore crosses the planes of the transverse corrugations substantially at right-angles thereto. If such a wall confines a fluid under pressure, as in the case of a collapsible and expansible vessel, the greatest strains in the metal at the bends when the corrugations are extended and collapsed, are not normalto the cor:

rugations, but are more or less displaced from a true normal direction and make more or less acute angles with the planes of the corrugations. As a result of thus shifting the working strains in the metal at the bends into a direction more or less across the grainwhere the tensile strength of the metal is less than in the direction of the grain, the endurance of the flexible corrugated wall does not reach its maximum.

It is therefore the primary object of this invention to overcome this objection and to provide a .flexible corrugated wall and method of making the same, whereby the grain of the metal may be so distributed in the corrugations, particularly at the bends, as to afford the maximum strength along lines of greatest strains, thereby giving to the wall a greater endurance, while retaining therein the desirable quality of thinness and flexibility.

These, together with other objects, will more fully appear in the detailed description and be pointed out in the claims.

The inventive idea involved is capable of expression in a variety of ways or methods of procedure, one of which, for the purpose of lllus'trating theinvention, is hereinafter specifically described, but is given solely for the purpose of illustrating the invention, and not for the purpose of defining the llmlts thereof, reference being had to the claims for this purpose.

In order that the invention may be more readily understood, reference is had to the accompanying drawings, in which Figure l is a view in elevation of a cor rugated metal. Wall; Fig. 2 is a View of a portion of the Wall highly magnified; Figs. 3 and 9 are views showing rolled sheet metal blanks; Figs. 4, 5, 10 and 11 are elevational views of .the cups; Figs. 6 and 7 areviews' showing the cup after being corrugated; and Fig. 8 is a vertical sectional view of a die for forming the blank cup. I

In Fig. 2 I have shown anenlarged view of a portion R, T, U, V of the side wall of a collapsible and expansible corrugated metal vessel thewalls of which are-subject to in ternal fluidpressure, for the purpose of indicating the direction of the strains to which the various portions of the wall are subjected under such conditions.

Fluid pressure within the vessel will exert on lateral walls 1, 2, equal and opposite forces 3 .normal to their inner surfaces tending to separate them. These lateral walls 1,

perspective 2 being unitedbythe curved portions, 5

constituting the bend of the corrugations,

this portion 4, 5 will be subjected to. a tensile strain in the direction G-H. Furthermore, when the flexible wall is collapsed and expanded, the curved portion 4, '5 will be the arrows 6, 7

Considering now any small unit of area I, J, K, L, on the curved portion 4:, 5 of the wall joining lateral portions 1, 2, and fixing attention upon any point 0 within this unit area, there are acting thereat two equal and opposite forces which may be represented in magnitude and direction by the lines 0 M, O-N, and two other equal and opposite" forces 0 P, O Q. The resultant or vector sum of any two forces, 0 M, O P, acting approximately at right angles to each other, is greater than either and is represente'd'by a line OJ. In like manner, the vector sums O K, O L, and O I, are each greater than either of the forces 0 P, O N, O Q, and Q It is evident that the greatest strains sustained in the bends of a flexible collapsible and expansible wall intended to sustain fiuidpressure from within or from without, are along the lines L O J and I O K. What has here been stated in respect to the portions of the outer corrugations equally applies to curved portions of the inner corrugations. The metal along these lines, therefore, should be especiall strong, and one of the main objects of tie present invention is to secure this needed strength means of a sheet metal drawing press hile at the same time retaining thinness of the wall.

v The preferred method by which I secure the objects of my invention, I will now de.

scribe. A sheet of metal such as brass, cop per or steel is rolled from a billet in the usual way, the grain of the metal lying parallel with the length of the sheet. A blank 8 is then out from the sheet, shown in Fi 3 as circular, though it may assume ot er forms such as oval or the like. The grain of themetal will then lie across the blank, as indicated by lines f f f. This blank is now shaped into a deep cup 9, preferably by avingsuitable drawing dies, diagrammatically indicated in Fig. 8. By successive drawings and occasional annealing of the metal, the cup can be given any desired depth. In the act of drawing the cup the original ain of the metal 7, f, f, is shifted so as to he along lines which are parallel neither to the axis nor the radius of the cup, as indicated in Figs. 4 and 5, in which, Fig. a shows the direction of the grain in the side correspondingto the side 10 of blank 8, and-Fig. 5 shows the direction taken by the grain corresponding to side 11 of blank 8. Another V i i Y im ortant result of the drawing 0 eration it resides in the fact that the friction etween the metal and the drawing dies toughens and strengthens the metal in directions more ing the blank 15 between the flange holder 13 and lower die 12, and more particularly that resulting from drawing the blanks over the curved mm 17, produces in the -metal a result similar to that produced by passing the blank through pressure rolls transverse to the grain of the blank, thereby strengthening the metal in directions transverse to the original grain. This die-drawn cup is peculiarly fitted for the next step of my process, which consists in deeply corrugating its. walls by means of corrugat-in rolls or by any other suitable means capable of efiectin the purpose. In Figs. 6 and 7, I have d agrammatically illustrated the cup with corrugations having their planes at right-angles to the axis of the cylinder, though they may be spiral in relation thereto. The lines 'f, f, (5, indicate the direction taken by the shifte grain along which the metal has been chiefly strengthened to resist the princi al bending strains. From what has prece ed, it will, however, be manifest that the metal has also been strengthened to a somewhat lesser extent, however, in lines transverseto f, f, f, due to the act of drawing the cup in the die. The corrugat-ing rolls have also a tendencyv to still further toughen the metal in the circumferential direction of the corrugations or across the general direction of the original grain, but it is to be understood that such toughening does not even approach that reduced by the pressure rolls in rolling the s eet metal from the billet, and is far less than that produced by the drawing of the cup.

The method above described results in producing a flexible corrugated wall of superior endurance, whether the fluid pressure on the wall be from within or without for the reason that the metal in the bends o the corrugations has been strengthened along the lines of greatest strain by shift1n the original grain into these directions, an also by materially strengthening the metal along lines across the original grain. These results, itwill also be noted, have been secured without sacrificing the advanta es of thinness of wall and flexibility whici are very essential in a metallic co lapsible and expansible vessel.

. It has been stated above that the act of die-drawing the cup strengthens the metal across the original grain. The strength of the sheet metal may be developed in directions more or less across the original grain by other means than that above described.

For example, I may pass the sheet metal once or twice between pressure rolls in the direction -of its breadth to thin the sheet somewhat, thereby materially increasing the tensile strength and. ductility in the direc tion across the grain,- without materially decreasing the tensile strength and ductility in the direction of the original grain. By reference to Figs. 9, l0 and 11, this will be apparent. Fig. 9 shows a disk of metal in the form of a circular blank similar to that of Fig. 3, except that the sheet metal from which it was cut has been rolled once or twiceat right-angles to the original grain. lhe heavy horizontal lines f, f, f, represent the original'grain of the sheet metal in direction and tensile strength, and the broken I 1 lines 7', f, f, in a similar manner represent the cross grain. 'lhis blank when drawn into a cup as described above, has a distribution of ,the two grains as indicated in l igs. l0 and 11, in which the dotted lines f, 7", f, indicate the effect of the cross rolladillicult task.

iug. When this blank is formed into a corrugated wall, asshown in Figs. 6 and 7, it will be readily seen from what has preceded that the tensile strength in the metal of the bends has been increased along the lines of griaitest-strain, thereby securing in the bend the greatest endurance while retaining a thin wall. My process also strengthens the lateral portions of the corrugated Wall, as'I have amply demonstrated by suitable tests. The metal sheet may also be cross-rolled to st reugthen-the metal in directions other than the original grain, and then bent into tubular shape so that the original grain would for such process accomplishes a three-fold result of (1) strengthening the metal in directions other than the original grain without materially weakening said gram; (2)

shifting the original grain at an angle to scribed in my Patent No. 762,300, dated June 7 14, 1904, I may draw several tube walls together by placing several blanks in the die at one time, and then separately cor'rugating each cup, which it will be found possesses all the characteristics of asingle die-drawn blank. 1

Before forming the corrugations, I may remove the end wall of the cup, thus leaving only the cylindrical wall, and I usually prefer to do so, and finally replace the bottom ivith a thicker wall.

What I'claim is:

1. A, vibratory corrugated tubular wall of metal having the grain of the metal in the bends of the corrugations directed in lines making acute angles with the axis of the tubular wall.

2. A vibratory corrugated tubular wall of rolled sheet metal having the grain of the 'n'ietal in the bends-of the corrugations directed in lines making acute angles w1th the axis of the tubular wall. it 3; A vibratory corrugated tubular wall of metal for confining fluids under pressure,

having the tensile strength of the metal in the bends developed in lines making acute angles with the axis of the tubular wall to correspond with the lines of greatest straln therein.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

WESTON M. FULTON. l l/Vitnesses: a Y

E. J. S. HYATT, J. C. TYLER.

Images