US2872865A - High strength fiber glass-metal construction and process for its manufacture - Google Patents

Description

Feb. 10, 1959 K. s. SKAAR 2,872,865

HIGH STRENGTH FIBER GLASS-METAL CONSTRUCTION AND PROCESS FOR ITS MANUFACTURE Filed Sept. 29. 1955 2 Sheets-Sheet l & 2| 6l6 2 3 \k R w? llllhlmlml INVENTOR. KARSTEN s. SK'AAR Feb. 10, 1959 K. s.sKAAR 2,

HIGH STRENGTH FIBER GLASS-METAL CONSTRUCTION AND PROCESS FOR ITS MANUFACTURE Filed Sept. 29. 1955 2 Sheets-Sheet 2 INVENTOR. KARSTEN' S. SKAAR ATTORNEY-S United States Patent HIGH STRENGTH FIBER GLASS-METAL CON- STRUCTION AND PROCESS FOR ITS MAN- UFACTURE Application September 29, 1955, Serial No. 537,593

9 Claims. (Cl. 102-56) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to improvements in high strength fiber-metal constructions and methods for their manufracture and more specifically to high strength joints between woven fiber-glass and-metal and to methods for effecting such joints.

With the advent of fibers made from plastic materials and the development of high strength plastics, numerous efforts have been made to develop plastic-metal combination constructions for various purposes. Obviously, for many applications, where great strengthandresistance to separation are not necessary, such joints present only minor problems. However, in certain specific applications, as for example in effecting the joints between metallic and plastic parts in rocket or warhead constructions, the development of joints of sufiicient strength to withstand impact and the stresses set up in the firing of a missile have presented extremely difficult problems. Prior tothe instant invention, no entirely satisfactory Patented Feb. 10, 1959 been discovered that where woven fiber glass is used for the sleeving with any of a variety of known plastic materials, a construction of adequate strength for use as a warhead may be achieved.

It is, therefore, an object of this invention to provide new high strength tubular articles comprising plastic main bodies and including high strength joints with metallic end members, and to provide methods for the manufacture of such articles.

Another object of this invention is to provide high strength warhead constructions comprising plastic tubular bodies and metallic end members, the joint between the plastic. and metallic members being of a high order of strength, and to provide methods for the manufacture of such warheads.

A still further object of this invention is to provide a technique for joining pre-fabricated woven plastic material to metallic end members by utilizing such material in the form of sleeving and by providing means effecting solution has been achieved, particularly in the case of warhead constructions.

The development of a joint strong enough to withstand penetration of an object, as for example steel plate,

without pulling apart is of extreme importance. The suc cessful development of such a joint makes possible the construction of warheads of adequate strength and less weight than prior art warheads utilizing metallic casings. Thus, the performance characteristics of the conveying missiles can be improved by the resultant decrease of weight or by the inclusion of a larger quantity by weight of explosive than could be. carried by equivalent prior art missiles.

This invention is based upon the discovery that woven fibrous sleeving may be used to form a shaped casing and to effect a strong joint with a metallic end member. If a length of such sleeving is turned back upon itself over a metal ring member, the ring member and the resulting double thickness of sleeving form a thickened reinforced end which may be tightly joined toa metallic end member as by turning in one or both of the lips of a prepared groove in the end member to clamp the reinforced end. Alternately, such a covered ring, member may be clamped between screw threadedly connected inner and outer metallic pieces to effect a strong and tight joint. If such sleeving is impregnated with an appropriate hinder or plastic material-(either before or after effecting the joint) and is cured after joining to the metallic structure in a manner appropriate to the nature of the binder or plastic used, theresulting structure is a rigid tubularabody having a tightly connected metallic end piece. In the foregoing manner, by appropnate clamping cooperation of such sleeving with a metallic end member to provide a joint of a high order of strength.

Another object of this invention is to provide high strength tubular articles made of plastic impregnated fiber glass having high strength joints with metallic end members and to provide methods for making such articles out of pre-fabricated woven sleeving to facilitate manufacture thereof.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: a

Fig. 1 is a vertical sectional view of the nose portion of a tubular casing according to this invention, illustrating the joint between the plastic tubing and the metallic nose structure; 1

Fig. 2 is afragmeutary vertical section of a modified form of construction according to the invention; and

Fig. 3 is a vertical sectional view of a modified inner flange member which may be used in place of the equivalent inner flange member shown in the modification of Fig. 1;

Figs. 4 to 9 are schematic showings of the steps of a method of forming a rigid tubular body of woven fabric and having a metallic'end member, according to this invention, Fig. 4 showing an elevation of a mandril on which the parts are assembled; Fig. 5 showing the mandril with the inner flange positioned thereon and a sleeve of woven fabric pulled thereover, the flange and fabric being shown in section; Fig. 6 being a view similar to Fig. 5 showing the end ring member'in position; Fig. 7 being a view similar to Fig. 6 showing the extended edge of the sleeving turned back over the ring;' Fig. 8 showing the final assembly, with 'the outer ogive member screw-threadedly engaging the inner flange to securely clamp the end ring and doubled sleeving in position;

' and Fig. 9 showing the assembly of Fig. 8 with the selection of hinder or plastic material, and by appropriate selection of woven or fibrous sleeving, high strength tubular bodies having extremely strong JOIDtS with metallic end members maybe formed and 1t has sleeving impregnated with a' suitable binder and positioned in a mold for curing.

Referring now to the drawings, in which like reference numerals are used to designate like parts throughout, tubular structures according to this invention are illus'- trated in Figs. 1 and 2 and comprise rigid tubular members generally designated as T, and having end portions of enlarged cross-section, as at R, by which a tight joint may be effected with metallic ogival nose pieces, generally designated as N. The rigid tubular members are laminar in construction, thelaminae 2, 4 being formed by bending one or more cylindrical sleeves back upon themselves over ametallic ring member 6 to form the enlarged cross-section R.

The joint between the tubular members and the ogival or plastic nose piece may be efiected in a variety of ways. In the particular joint shown in Fig. 1, 8 is an inner flange member in the form of an annulus having a narrowed, cylindricalforward portion 10, and an outwardly flaredrearward portion 12. Theforward portion 16 is screwthreaded externally as at 11 for substantially its entire length and is smooth externally for a portion of its length at the point of juncture with the flaredportion 12, as shown at 14, to provide a bearing for the inner diameter of the enlarged portion R of the tubular her. Theouter surface 16 of the inner flange member is bowed outwardly, as shown, to :provide surfaces to resist longitudinal relative movement of the parts when the joint is completed. For cooperation withinner flange 8 in clamping enlarged portion R to hold the tubular member T in position, there is provided an ogivalouter clamping piece 18, which is in the form of an annulus.Outer piece 18 has aninner screw thread 19 for cooperation with theexternal screw threads 11 ofinner flange 8. At the rearward end ofouter piece 18 the thickness of the wall of the annulus diminishes abruptly, to form ashoulder 20, the outer end ofthe shoulder terminating in acurved surface 21 of a radius to grip enlarged portion R. The annulus extends rearwardly into a continually diminishingskirt 22 having a curvedinner surface 24 of such configuration as to cooperate with the surface .16 of the inner flange member to clampingly grip theside walls 2, 4 .of the tubular member T, the enlarged end portion R of the tubular member being clamped between theshoulder 20 and thesurface 21 ofend piece 18, thesmooth wall 14 ofinner flange member 8 and the forward cooperating portions ofcurved walls 16 and 24.

Fig. 3 illustrates a second form ofinner flange member 12 which may be used to replace theinner flange member 12 as shown in Fig. 1 where less clamping area along tubular member T is required. Member 12' performs precisely the same functions as themember 12 in cooperating with thenose piece 18, clamping the enlarged portion R between thesurfaces 14' and 16 of theinner flange member 8, andsurfaces 20, 21 of theouter piece 18.

Fig. 2 is illustrative of another modification of the present invention, in which the ogival nose structure is of one piece, the clamping of the enlarged portion R being effected by deformation of the metal of the side walls of a previously prepared groove. Thus, the nose piece comprises a single piece ofmetal having lips 26, 28 extending rearwardly from agroove 30 of a size to receive enlarged portion R, the lip portions being formed witharcuate surfaces 32, 34 corresponding to thesurfaces 16 and 24 of Fig. l, to clamp the tubular member T and to resist longitudinal separation after completion of the assembly. The structure as shown in Fig. 3 is made by forming nose-piece N with thelips 26, 28 spread apart to form a groove for insertion of the tubular member therein and one or both of the lips are then turned in to grip the tubular member as shown.

In effecting the plastic-metal joints discussed hereinabove to form the illustrated tubular structures, the tubular member T may be any rigid plastic material of proper size and shape, having an enlarged end portion R. However, as explained hereinabove, this invention is particularly concerned with the employment of impregnated woven fabric such as fiber glass fabric or fiber glass fabric modified by the inclusion of other materials as asbestos fiber, for example. When such materials are used in the manner previously discussed, i. e., as flexible sleeving bent back upon itself over an end ring to form an enlarged end and a laminar wall structure, the joint with the metallic parts may be formed either before or after impregnation of the fabric with the plastic material Thus, the end ring-sleeving assembly may either be olned to the nose piece as in Fig. 1 or Fig. 2 while still flexible in form and subsequently impregnated 'with t binder .of plastic and cured, or said assembly may be formed and hardened and then assembled with the nose piece. Furthermore, the wall thickness and number of laminations in such tubular members may be varied by selection of the nature of the sleeving and the number of thicknesses thereof employed.

As previously indicated, the binder or plastic employed to give strength to the sleeving may be any one of a Wide variety of plastics. Thus, for example, any of the known epoxy resins, polyester resins or phenolic resins may be used as the plastic material, and suitable catalysts may be intermixed therewith when necessary or desired, to assist polymerization and cross-linking of the plastic compound. Examples of such catalysts are benzoyl peroxide (for use with the polyester resins); metaphenylene diamine, 4,4 methylene dianiline and boron trifluoride monoethylamine complex (all for use with epoxy resins; and hexamethylene tetramine (for use with phenolic resins). The specific nature of the hinder or plastic material and/or catalyst is not of the essence of this invention, a wide variety of such materials being known to have properties obviously suitable to the purposes of this invention.

The methods of manufacturing articles as described above may be varied. Thus, a pre-stiffened tubular member may be clamped between screw threadednose piece elements 8 and 18 as in Fig. 1.; between thelips 26, 28 of the nose piece of Fig. 2; or betweenelements 18 and 8' if the inner flange of Fig. 3 is used. Such a tubular member may be formed of a plastic as by molding; by impregnation and molding of plural laminar constructions of filter glass materials in which, if desired, the direction of the fibers of alternate layers may be arranged in a prescribed fashion; or if the woven sleeving which is the specific illustration of this disclosure is used, a length of sleeving may be pulled over a mandril for a portion of its length, the remainder being pulled through a metallic ring member (see Fig. 6), and then turned back on itself (Fig. 7). Impregnation of the sleeving with a desired plastic material may be either before or after the bending of the sleeving back upon itself as by wiping the plastic on. The assembly is then heat curved in a mold to give it its final rigid shape. Impregnation may also be effected by placing the unimpregnated sleeving and ring assembly into a mold, pouring the plastic into the mold and then curing the assembly.

Alternatively, assembly may be effected by directiy connecting the flexible sleeving to the nose-piece prior to impregnation or stiffening thereof, and an illustrative example of onesuch procedure is depicted more or less schematically in Figs. 4 through 9. In this process, an appropriately shaped mandril M, as shown in Fig. 4, is utilized. Aninner flange member 8 is positioned over the properly shaped end of the mandril. As shown in Fig. 5, aftermember 8 is in place, a length of woven flexible sleeving is pulled over the mandril, the sleeving being of such a length that upon bending back of the tubing about reference line a--a of Fig. 5 a tubing of at least a length and thickness desired will be obtained. Thus, if plural plies for the full length are desired the tubmg must be at least twice the desired length, but the length could be less if a partially single-ply structure were desired. Reference line a-a is located to indicate the ultimate position of the enlarged portion R, aboutsection 14 of theinner flange 8 as shown in Fig. 1.

After the sleeving is positioned about the mandril and inner flange assembly as described in the preceding paragraph and shown in Fig. 5, themetallic ring member 6 1s positioned by pulling it over the free end of the sleeving to form the assembly shown in Fig. 6. Then the sleeving is bent back upon itself over ring member a to form a two-ply tubular structure comprising theinner ply 2 and the outer ply 4 formed by the free end, and having the enlarged portion R as shown in Fig. 7

The assembly is completed by screwing theouter piece 18 onto the inner flange member, cooperatingscrew threads 11 and 19 causing thepieces 8 and 18 to be tightly connected and to clamp the tubing assembly as shown in Fig. 8 (and in Fig. 1). In this procedure, the sleeving may be impregnated with the desired plastic material by vacuum techniques or other known techniques such as by being wiped into the sleeving, in its position over the mandril, as shown in Figs. 6 or 7. The impregnated assembly, after connection withouter piece 18 may then be placed in a mold 50 (preferably two-piece) for heat curing and shaping. Alternatively, the assembly of Fig. 8, unimpregnated, may be placed in the mold and plastic material allowed to flow into the space occupied by the woven fabric material. After saturation, the mold is placed in an oven for an appropriate time at a temperature proper for curing the particular material used.

From the above it should be obvious that this invention provides new and improved tubular constructions characterized by great strength and by improved strength in plastic-metallic joints forming a part thereof. Moreover, this invention provides novel methods for the manufacture of such constructions.

Obviously, many modifications and variations of the constructions and processes forming the present invention are possible in the light of the above teachings. It is therefore to be understood that the. illustrative examples given are not intended to be limiting in nature, the scope of the invention rather being defined and described in the appended claims:

What is claimed is:

1. A tubular construction comprising a tubular main body formed of originally flexible fabric sleeving folded back upon itself to form a plurality of plies joined by a fold, a reinforcing ring member positioned between said plies at the fold to form a thickened end, a rigid tubular end structure, said end structure having means to clampingly engage said thickened end to join said main body and said end structure to form a unitary tubular construction, said flexible fabric being impregnated with shape retaining plastic material for giving said impregnated fabric a high order of rigidity and strength, said rigid tubular end structure comprising an inner flange member and an outer clamping piece, said inner flange member having a skirt portion to support the walls of said main body member adjacent the thickened end thereof and having an externally screw threaded portion extending outwardly through said thickened end, said outer clamping piece having an internally screw threaded portion for cooperation with the external threads on said inner flange member, an outwardly directed shoulder at the rearward end of said threaded portion and a rearwardly directed skirt portion complementary to that of the inner flange whereby the thickened end of said main body may be clamped between said shoulder and the cooperating adjacent forward ends of said two skirt pornuns, and the main body wall adjacent said thickened end may be clamped between said two skirt portions when said inner flange member and said outer clamping piece are screw threadedly engaged with one another.

2. The tubular construction of claim 1 wherein said two complementary skirt portions are outwardly flared whereby longitudinal forces tending to separate the main body from the end structure are resisted.

3. The tubular construction ofclaim 2 further characterized in that the flexible fabric is a woven fabric containing glass fibers and is impregnated with a shape retainmg plastic material whereby it has a high order of rigidity and strength.

4. The method of manufacturing a composite tubular body which comprises the steps of pulling a portion of a length of normally flexible fabric sleeving through an end ring member and folding said length of sleeving back upon itself to form a tubular main section having a muIti-ply wall and a thickened end, afl'ixing an end structure about said thickened end and about the adjacent niulti-ply wall of said main section, and impregnating said fabric with a plastic binder material to impart strength and rigidity thereto.

5. The method of claim 4 wherein said plastic binder material is an incompletely polymerized and incompletely cross-linked binder material and wherein the assembled composite tubular body is then cured to complete polymerization and cross-linking of the binder material to produce a strong and rigid structure.

6. The method of claim 5 wherein the fabric is of woven material including fiber glass.

7. The method of claim 5 wherein said end structure comprises a unitary tubular construction having a pair of outwardly flared spaced integral lips extending longitudinally thereof to form a groove, said clamping being effected by pressing said lips together to clamp said thickened end and multi-ply wall.

8. The method of manufacturing a cylindrical com posite fiber glass-metal cylindrical body which comprises rolling a cylindrical open ended fiber glass sleeve of the required diameter back on itself with a ring enclosed at the fold between the two cylindrical plies formed, aflixing the enclosed ring internally of a cylindrical metal part near the end of the metal part to be joined to the fiber glass sleeve, impregnating said fiber glass sleeve with a plastic binder, forming said sleeve to the desired shape in a mold and curing said binder.

9. The method of manufacturing a composite tubular body comprising the steps of providing an inner flange member having a rearwardly extending outwardly flared skirt and a forwardly extending externally screw-threaded portion, positioning a mandril having a reduced forward end into said skirt portion to support the flange member on said forward end of the mandril, placing a tubular woven fabric sleeving of length greater than the mandril over the mandril and inner flange member with a portion of the sleeving extending forwardly of the inner flange member, pulling a ring member over said forwardly extending portion of the sleeving and positioning said ring member about said sleeving in the plane of the line of connection of the flared skirt of said inner flange to the forward portion thereof, folding back said forwardly extending portion of said sleeving upon the remainder of the sleeving on the mandril to form a multi-ply tubular wall, screwing a complementarily shaped outer clamping piece down onto said inner flange to clamp the sleeving and ring assembly between said inner flange member and said clamping piece, placing the assembly in a mold, flowing thermosetting plastic material into the mold to fill the interstices of the fabric sleeving with said plastic material, and curing the thus impregnated assembly to solidify the assembly to form a rigid, strong composite tubular structure.

References Cited in the file of this patent UNITED STATES PATENTS 1,974,383 Wallace Sept. 18, 1934 2,099,915 Weatherhead Nov. 23, 1937 2,146,218 Kimmich Feb. 7, 1939 2,146,756 Miller Feb. 14, 1939 2,241,355 Machlachlan May 6, 1941 2,359,952 Welger Oct. 10, 1944 2,368,911 Andler Feb. 6, 1945 2,408,960 Stivason Oct. 6, 1946 2,500,117 Chandler Mar. 7, 1950 2,612,925 Starr Oct. 7, 1952 2,653,887 Slayter Sept. 29, 1953 2,681,619 Chandler June 22, 1954 2,685,458 Shaw Aug. 3, 1954 2,741,496 Melsom Apr. 10, 1956 FOREIGN PATENTS 402,535 Great Britain Dec. 7, 1933 1,098,880 France Mar. 9, 1955

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