US2391997A - Composite slab sheet or plate - Google Patents

Description

' Jar l, 1946,. w. NOBLE 2,391,997

COMPOSITE SLAB SHEET OR PLATE Filed March 26, 1942 s Sheets-Sheet 1' Jan. 1, 1946. w. NOBLE 2,391,997

COMPOSITE SLAB SHEE'i OR PLATE Filed March 26, 1942 3 Sheets-Sheet 2 W ar2;en JVb Z Ze Jan. 1,1946. w. NOBLE V COMPOSITE SLAB. OR PLATE Filed March 26, 1942 3 Sheets-Shet 3 zqa gm Warr en Maj 1e,

Patented Jan. 1, 1946 Warren Noble, Washington,

D. 0., assignor to Lilly Florence Shlrley Noble, Garden City,

Application March 26, 1942, Serial No. 436,345

9 6 Claims.

Thi invention relates to a new article of manufacture in the form of a slab or plate of almost any formable substance composed of two thinner sheets or plates, one of which is smooth, the other so arranged as to surface as to act to space, stiifen and aid in joining the composite sheet to another or to an adjacent member. The purpose of the invention is economy; economy of material, of weight, of fabricating time and in the nature of the machinery of fabrication, of labor and of heat necessary in making the joint and lastly by making possible structures of superior rigidity without encroachment upon space interior to the walls of the structure.

A plate so made will approximate the stiffness of a solid sheet of similar dimensions against some stresses and even exceed it in others, despite a weight ratio of solid to composite of not less than five to one. For some purposes this ratio may even be exceeded although the tensile strength of the composite sheet, as compared with the solid plate will remain in the approximate ratio of the areas of metal in the contrasted cross sections. Modern design, however, rarely needs to concern itself with strength per se. It seems invariably true that a structure sufficiently still for its purpose is strong enough under all its working conditions.

Costs of material and fabrication aside, light structure has so infinite a scope in progressive design as to demand the utmost attention to its devisement, especially in the transportation fields. Material made under the instruction of this invention would substitute for solid section of similar depth, eliminate necessity for much auxiliary structure, yet maintain the low weight desirable both for better function and cost reduction.

Aerial craft daily advance in importance as a class of manufacture so any simplifying factor in design is of interest.

. Ship building, at the moment is seriously hampered by shortage of steel on the one hand and by the lack of facilities for fabricating heavy plate on the other.

Our national facilities, however, have been of late years vastly expanded as to light gauge sheet and a surplus of machines for fabricating light gauge metal actually exists without prospect of employment in the present situation.

While ship construction based on composite plate of this type would be unconventional it might be helpful in enabling existing machine equipment to manipulate vital material to a vital purpose at less cost, with less material, with less energy, human andotherwise and with a more competent end result.

While the initial statement of this application "this invention relates to a new, article of manufact is technically correct it would be equally true to say it outlines simple structures may be quickly made with a minimum of material and energy.

In the accompanying drawings:

Figure 1 is a perspective, sectional view form of the invention.

Figure 2 is a perspective view of an adjoining strip.

Figure 3 is a section on line 33 of Figure 2.

Figure 4 is a section on line 4-4 of Figure 2.

Figure 5 is a sectional view showing the manner of joining two elements of the type shown in Figure 1.

Figure 6 is a perspective, sectional detail.

Figure 7 is a plan view of a modified form of the invention.

Figure 8 is a section on line 8-8 of Figure 7.

Figure 9 is a plan view, with certain parts broken away, showing another modification.

Figure 10 is a section on line Ill-l0 of Figure 9.

Figures 11, 12 and 13 are sectional views of further modifications.

Figure 14 is a sectional view, illustrating one method of securing a structural element to the article of the present invention.

Figures 15 and 16 are plan and sectional views of another modification.

Figure 17 is a sectional view of a modified form of joint between two adjacent sections, and

Figure 18 is a diagrammatic view showing a preferred method of welding adjacent sections.

In a preferred form of fabrication, two sheets of material in, I I of similar dimension and char-' acter are taken. One sheet In is left smooth, the other embossed, as at l 2 to suitable depth and pattern to provide the desired thickness of the composite plate when superimposed upon the smooth sheet. The two are then welded together at the points of contact l3, becoming a single unit which thereafter may be treated precisely as a solid sheet might be. The weld l3 may be a zone of spot welding in the form of a series of circumferential spots around the opening it, formed, for instance, by a series of projections, or the weld I 3 may be a continuous line formed by a hollow cylindrical electrode welding around the periphery of the opening it. To become specific for the sake of clarity let us take two similar sheets of steel of a thickness easily produced by a continuous rolling mill, leave one sheet alone but on six inch centres of one a design system whereby.

in staggered but symmetrical arrangement pierce half inch holes l4 and draw down angularly walle'd cups l5-like patty pans-from the zone surrounding each hole, the depth of the cup to depend upon the final thickness of assembly desired.

Such pans or depressions I! can be drawn down, where a central hole It exists, without materially distorting the surrounding metal so the exterior dimensions will not be affected and the two sheets can be superimposed with edge parallel to edge. The welding [2 takes place about the pierced bottom of each patty pan l5, by any of the methods suggested above.

While joints may be fewer in a structure built from this composite sheet since longer lengths of thin material can be rolled. handled and welded together than possible with the heavy solid plate the joining of composite sheets in a manner to assure fluid tightness and at the same time avoid weakness at the joint is part of the problem and of this invention. One method, as indicated in Figures 2-6, employs a backing strip 20 for the interstice formed between the sizes or shapes as laid up, the depressions or pans IS in th embossed sheet being divided in halves along the border zones, these halves lacking depth as compared with the other depressions IS in the sheet area by the thickness of the metal of the backing strips 20 in order to nest in reinforcing pockets 2i in the strip, similar in all form respects to the embossments l5-l6 used on the stay sheet except for an interpocket channelling 22. Thus the backing strip presents a continuous smooth surface when in place immediately behind and in contact with the smooth surfaces while the pockets 2| in the strip embrace the half embossments I6 left at the edges drawing them tight together.

Projection welding spots 23 are formed at the mouth of these pockets and along the flange 24 of the channel portions. These spots may be in the form of fine edged rings 23 swaged by pressure from the neighboring metal. By the use of suitable electrodes it is possible to weld the backing strips 20 to the embossed sheet Ii at the projection welding spots 23 and to weld the smooth sheet joint between sheets and to the face 25 of the backing strip channel portions 22, securing a smooth joint for the outer face or skin iii of the structure and ample reinforcement for the embossed face. notwithstanding the fact that the backing strip 20 is completely enclosed within the walls of the composite elements. Projections similar to those shown at" may be employed at the contact surfaces of the sheets to be joined. The smooth plates l0 and the embossed plates ii are welded with their ends butted at the lines of division contact.

Apart-from the terial the use of direct economy of primary malight sections of metal aid the welding characteristics making for speed and the use of less electric current or gas. The backing strip helps in making welds and at no time does spot welding have to be attempted through double thickness. The embracement of the half cups l6 by the double thickness backing strip relieves the weld of much of any strain which may later be imposed and assures the true positioning of adjacent plates each to each prior to welding.

It is not essential for facing and backing sheets to be similar in gauge or analysis. Dissimilar thicknesses and analyses may be used in accordance with ordinary welding practice. Thus a stainless steel may be used for the smooth surface ll matched with a cheaper sheet ll.

grade for the stay 1 accurate within ordinary precision limits and it may be found useful, for some service to carry indications of the centres through the smooth plate so a gun welder may be properly located from the smooth side.

In forming the joint of the type shown in Figure 5, a pair of composite plates of the type shown in Figure 1 are first prefabricated, by welding the embossments l5 to the smooth sheets ill, along lines I3, but leaving the bottoms of the embossments i6 and i6 spaced from the sheet I. as indicated at 21, a distance equal to the thickness of the metal in the channel member 20. Because of the inherent spring of the metal in the composite plates, the sheets I0 and i I may be separated slightly along their edges and the channel member 20 inserted by a combined sidewise and rotational movement about its longitudinal axis so that the edge embossments i8 and ii are positioned within the pockets 2i of the backing strip 20. The next plate may then be joined by similarly spreading the plates II and il along their edges and positioning the half-embossments within the unoccupied halves of the pockets 2|.

The dimension of the spaces 21 between the bottoms of the half or quarter embossments l6 and i6 is such that the bottom 25 of the jointing cups 2| are pinched between the smooth plates and the embossments, under the inherent springiness of the metal. Also, the projections 23 somewhat spread apart the embossed sheets and the smooth sheets which subjects the projections to the spring pressure of the metal.

This spring contact is most useful in followin up the weld when welding current raises the projections 23 to welding heat, which occurs after the parts have been assembled as just described.

In forming the welded joint between the composite plates assembled in this manner, a central electrode contacts the bottom 25 of the channel 2| through the opening at the center of the half or quarter embossments, as well as the periphery of the embossments IS, IS. Heavy spring followup is preferably used to assure ample pressure at the projections and along the flanges of the channel. This operation may leave the edges of the smooth plates l0 slightly apart, but in firm con tact against the bottom surface 25 of the channel. Thereafter, these edges are electrically or otherwise welded together to secure fluid tightness and to anchor the edges of the plates I. to the surface 25 of the strip. Being of light gauge, the metal is swiftly brought to welding temperature and a completely supported joint is made.

It will be understood that, when the composite plates are assembled, a pair of adjacent quarter embossments ii at the corners will be disposed adjacent to each other and preferably opposite to a half embossment IS on the edge of the next composite plate so that the lines of junction between the plates may be staggered and disconcentre distances of embossments are entirely a,

matter of material and conditions.

There is merit in double welding, i. e. along both inner and outer sheet Junctions but the process is slower and in the main the seam weld along the inner seam is unnecessary.

The shot welding of the reinforcing cups should in any case be retained.

Sections of composite sheet may have other than parallel sides. For example as indicated in Fig. 11 a tapered wing might be built by using graded depths and pitches for the embossments. Sections having more than two plane surfaces may similarly be constructed.

In general the embossment in the form of a truncated right cone having a circular base will be found completely adequate but'special conditions may arise wherein anelliptically based embossment, as indicated at 40, ll in Figures and 16 will prove advantageous in searching for the ultimate economy of weight.

- 3 ing product is exceptionally stable and stifl', since the chordal sections or flats act as straight brace. members and restrain bending.

The tapered composite plate, as indicated in Figures 11 and 12 has numerous advantages over corresponding solid plates, particularly from the 'a diflicult task to roll out or point of view of initial manufacture, since it is machine down a solid plate to a variable thickness.

Figure 14 indicates a preferred method of attaching a composite sheet to structural members, such as bulb angles and the like. The embossed plate II is apertured at 50, 5| for the reception of clamping bolt assemblies 52 and for the foot electrode 53 of a welding apparatus, the upper electrode 54 being positioned to engage the flange 55 of the bulb angle.

Staggered pitch in symmetrical pattern may 1 be less efllcient than a pitch arrangement patterned to meet the loading conditions. Stepped overall thickness may have place in transition of zones of section. Such matters are in the province of design and in no way depart from the spirit of the invention.

Figures 7 and 8 illustrate an unpierced cone type of embossment in which the apex 3| of the cone it'll-being thinned in the draw provides its own welding projection.

Figures 9 and 10 indicate the method of using double embossment to produce a double faced smooth plate.

Smooth plates 33, 35. are welded to the ends of downwardly and upwardly projecting cones 35, 36, respectively, pressed from the intermediate embossed sheet 31, the latter acting as a stiffening member for the two smooth plates. As indicated in Figure 9, the cones are preferably staggered, but any other arrangement may be adapted, depending upon the use to which the composite plate is to be put.

In Figure 11 a diagrammatic representation of a tapered structure is given showing change in depth and pitch of the cups 38 both as demanded by optimum design considerations and by the practical conditions governing the relation of diameter to depth of draw. A curved surface is represented by Figure 13. Its purpose is to indicate the use of chordal flats 45 between the pitch of the embossments 46. This advantage in stability comes from delaying the welding operation until after the desired bend in the smooth plate is established. While Figure 13 shows cones for embossments, the spherical embossment 41 shown in Figure 13 are often preferred. Moreover the spherical embossments are of particular utility in tapered sections. as shown in Figures 11 and 12.

The advantages of the use of the present invention in connection with the curved sections will be apparent when consideration is given to the difliculties encountered in bending solid plates of substantial thickness. Operations of this type require heavy machine tools and the expenditure of considerable power. With a composite sheet in accordance with the present invention, similar results may be accomplished quite readily by bending each of the elements of the plate, before the sealing operation is performed. The result- Figures 17 and 18 illustrate modifled'joints between adjacent composite plates. The smooth plates I lie have their as indicated at 51. The embossed plates llahave their marginal portions 58 disposed on down-' wardly inclined planes and their edges 59 turned upwardly, thereby providing marginal channels 60 for the reception of roller electrodes BI, 62, adapted to function in the manner fully described in my co-pending application for patent, Serial Number 388,853. Welding current flows from one electrode through the upturned edge 59 of the embossed plate, through the two flanges of the smooth plates Ilia, then'through the other edge 59 and finally to the other electrode. Since. the metal is relatively thin, the roller electrodes 6 I, 62 may be moved along the joint quite rapidly, to provide a continuous welded seam.

If desired, the opposite, smooth face maybe welded, as indicated at 53.

The flanges 51 of the smooth plates Ilia may extend a substantial distance beyond .the embossed plates, as indicated at 64, to serve as a reinforcement.

In some cases it may be desirable to reinforce the smooth skin sheet against local puncture. This can be done by filling the space between the sheets with a setting compound, including cement or plaster. The filler may be inserted in unit form or poured in plastic condition. Preferably, however, jointings are left free of compound so that the back strip can be inserted and the welding operations performed. In some cases,

general stifl'ness and resistance to torsion would approximate that to be expected if plates of similar solid thickness were to be employed. Thus a wall depth of say three inches using 11 gauge plate would only weigh the same as the same area of inch solid plate-a thickness much too light to be used without close framing. The total weight of such a hull would approximate onefourth of that of normal conventional construction, and fabrication facilities could be found almost anywhere in the U. S. A. Production of suitable sheets could be effected on continuous mills and the handling would be lighter so avoidmargins turned upwardly ing much of the diiiiculty of cranage supply. For equivalent lines the eflective hull space would be much reater.

In aircraft work avoidance of the myriad rivet holes would make for simpler, cheaper and more aerodynamically eillcient general arrangements of plane elements.

The cost of compoflte plate is almost directly as the weight if material alone is considered, since the fabricating cost of the embossed member is very small with proper equipment. It handling machine overheads and assembly welding are included the potential saving over solid metal is large. Contrasted with equivalent structure characteristics obtained with solid plate and contributory framing the economy is striking.

The use of the terms "weld" and welding used throughout this specification must not be taken to preclude the use of other methods of firm attachment under other circumstances and with other materials. Thus brazing in controlled atmosphere furnaces would be satisfactory so far as the junction between the plates is concerned, equally so silver soldering with or without atmosphere control. With non-ferrous metals, soft soldering would be adequate for many purposes. Even castings cored between surfaces to achieve the generic form of spaced plates connected by a multiplicity of right cones would provide the stiffness aimed at with economy of weight.

Although the invention has been described with considerable particularity, it must be understood that it is not limited to the details of construction described above and shown in the accompanying drawings, but includes all modifications coming within the scope of the appended claims and their equivalents.

I claim:

1. In combination, a plurality of composite plates and means for joining the same together in edge to edge relation, each plate comprising a substantially smooth sheet and a sheet having a plurality of tapering embossments formed therein in symmetrical, staggered relation and welded to the smooth sheet, and a plurality oil 5 similarly tapered half embossments along the edges of the embossed sheet, said means for joining the composite plates together comprising a member having a tapering pocket embracing the two half embossments of two adjacent plates and a welded connection between the member and the smooth sheets of each plate.

2. In combination, a plurality of composite plates and means for joining the same together in edge to edge relation, each plate comprising a substantially smooth sheet and a sheet having a plurality of embosments formed therein in symmetrical, staggered relation and welded to the smooth sheet, and a plurality of half embossments along the edges of the embossed sheet with the ends thereof spaced from the smooth sheet, said means for joining the composite plates together comprising a channel member having pockets embracing the two half embossmerits of two adjacent plates and a weldedconnection ,between the half embossments, the pockets in the channel member and the smooth sheets of each plate.

3. In combination, a plurality of composite plates and means for joining the same together in edge to edge relation, each plate comprising a substantiall smooth sheet and a sheet having a plurality of embossments formed therein in symmetrical, staggered relation and welded to the smooth sheet, and a plurality of half embossments along the edges oi. the embossed sheet, and quarter embossments at the comers thereof, said means for joining the composite plates together comprising a member having a plurality of pockets embracing two adjacent mating half embossments of two adjacent plates and four quarter embossments at the corner of four adjacent plates, and welded connections between the embossments, the pockets in the member and the smooth sheets of each plate.

4. In combination, a plurality of composite plates, means joining the same together in edge to edge relation, each plate comprising a substantially smooth sheet and a sheet having a plurality of substantially conical embossments formed therein in symmetrical staggered relation and welded to the smooth sheet, and a plurality of half embossments along the edges of the embossed sheet and quarter embossments at the corners thereof, said means for joining the composite plates together comprising a member having a plurality of pockets, certain of which embrace two adjacent mating half embossments of two adjacent plates, and others or which embrace one half embossment of one plate and two quarter embossments at the corners of two adjacent plates, and welded connections between-the embossments, the pockets in the member and the smooth sheets of each plate.

5. A slab-like composite plate adapted to be assembled permanently with other plates of similar construction and matching edges, and means for securing the plates together, each of said plates comprising a smooth sheet welded to an embossed sheet, the depth of the embossments plus the thickness or the smooth sheet aggregating the thickness of the plate, the margins of the plate being defined in part by edge embossments projecting from the embossed sheet and being of less depth than the space between the sheets, thereby providing a space between the edge embossments and the smooth sheet to permit the insertion of said means for securing the plates together, the last-mentioned means comprising a member disposed entirely within the thickness of the plates and interposed in part between the edge embossments and the smooth sheets, spanning the lines of junction between adjacent plates and embracing the edge embossments and drawing the same together, and a welded connection between the edge embossments, the member, and the edges of the smooth sheets.

6. In combination, a plurality of composite plates and means for joining them together in edge to edge relation, said plates each comprising a smooth sheet and a sheet having a plurality of integral, spaced embossments welded to the smooth sheet, said joining means comprising a member disposed completely within the thickness of the plates, spanning the edges thereof and joined to the embossments on the edges of the embossed sheets and to the smooth sheets by welding.

WARREN NOBLE.

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