Abstract: A leaf spring of composite fibre plastics material comprising a plurality of layers of fibre material which are disposed in superposed relationship and which are embedded in a synthetic resin matrix, wherein there are provided outer layers (1) of fibre material which extend over the entire length of the leaf spring and which are associated with the tension and compression zones and shorter inner layers (2) of fibre material of a length which is stepped in a direction towards the central zone (N). In addition to the stepped inner layers (1), also provided in the region between the neutral zone (N) and the tension and compression zones respectively are intermediate layers (3) of fibre material, the length of which is greater than the length of the adjacent inner layers (2) of fibre material.

Abstract: A vacuum-tight nonmetallic Dewar component is fabricated from composite material of nonmagnetic fibers in a resin matrix. The component is cylindrical with a closed end, and is laid up from sheets of the composite material and circles cut from the sheets to form the closed end. The layers are mechanically worked and debulked repeatedly during layup between the addition of successive layers, to remove irregularities that can cause vacuum leaks. The joints between the sheets applied to the cylindrical surface and the circular end pieces are mechanically worked to effect a vacuum-tight seal, and the joints are staggered as between succeeding layers for strength and integrity. The laid up and debulked piece is finally cured.

Abstract: A method for producing pipeline having a thermally insulating coating in which a continuous matrix of water-impermeable material has dispersed throughout it hollow microspheres or cellular particles which improve on heat insulating properties of the basic matrix.

Abstract: A roller is characterized by an inexpensive and disposable construction for use in transporting and applying developer material in a developer system of a xerographic copier machine, and a method of fabricating such rollers. The rollers have an outside electrically-conductive surface for transporting and applying developer material and are constructed of a tubular fiber core, preferably spirally-wound and laminated paper plies, with an outside surface ply of aluminum foil spirally-wound on and laminated to the fiber core. At least those rollers which are utilized as applying rollers have spaced-apart grooves formed in the outside surface of the roller and formed therein without tearing or cracking the thin aluminum surface ply.

Abstract: The method of making a non-metallic bearing assembly by bonding a first layer of uncured rubber that is wrapped on a mandrel to a fiberglass layer whose outer wrappings are impregnated with epoxy resin. The fiberglass outer layer is cured first to form a rigid outer plastic shell and then the uncured rubber is vulcanized to give an inner rubber sleeve whose inner periphery has polygonal contour which is the cross sectional configuration of the mandrel. An inner layer of fiberglass, cement impregnated, interconnects the fiberglass outer plastic shell to the inner rubber sleeve.

Abstract: A method of manufacturing a composite structure of ceramic material which is reinforced by refractory fibers, wherein a slip (11) is prepared from a synthetic resin having good wetting properties on ceramic material and fibers, embedding fibers (15) in the slip, eliminating the liquid phase from the slip by drying (16), eliminating the synthetic resin from the formed structure by heating, and sintering the fiber-impregnated ceramic material, wherein a synthetic resin solvent is incorporated in the slip, and wherein the fibers are inserted in the slip in the form of an assembly which is a sheet or roving, before the drying.

Abstract: A high speed apparatus for sealing the tail of a wound roll of sheet material. A pair of parallel rotatable rollers define a tail separation station and a tail wind-up station that are disposed longitudinally along the length of the rollers. An entry station is located parallel to the tail separating station and a pivotable kicker is positioned to engage a roll at an over-center position to impart rotation to the roll and transfer the roll to the tail separation station. Air jets located at the tail separation station act to separate the tail from the body of the roll. The separated tail is drawn across a supporting surface and a sensor associated with the surface senses the end of the tail and acts to stop rotation of the rollers. As rotation of the roll stops, the separated tail falls onto a generally horizontal apron and the roll with the separated tail supported on the apron is then moved longitudinally along the non-rotating rollers to the wind-up station.

Abstract: A method of and apparatus for making, and the resulting material for fabricating reclosable bags and in which a length of web of predetermined width of bag material as wound on a mandrel has fastener strip sections joined to and across the width of the web. The web is adapted to travel continuously spirally about the mandrel. The fastener carrying web may be folded longitudinally and resiliently flexible profiles of the folded fastener strip sections separably joined. Ends of the fastener strips before, and after, folding may be flow melted and fusedly flattened. Ends of the fastener strips may be aligned with a fold juncture of an underturned flange of the web and the margin then unfolded to extend beyond the strip ends.

Abstract: An ablative thermal barrier on the interior surface of a cylindrical combustor is made by first molding a silicone rubber strip with shaped edges. The strip is then laid inside the combustor so that it runs circumferentially either as a helix or as a series of circles. The adjacent turns are spaced apart by a gap into which is interposed a thermosetting polymer material. The rubber is then pressed radially outward so that the adjacent turns are caused to press laterally against each other. The thermosetting material is then cured while in its resultant compressed condition, to make the material into a circular or helical rib which better retains the rubber in place during use.

Abstract: This invention relates to an improved composite material leading edge/spar member for an aircraft control surface, and the like. The present invention provides a one-piece composite leading edge/spar member that is of a lighter and stronger construction offering dimensional stability, and an efficient method for manufacturing the same is also provided. A one-piece leading edge/spar member (12) includes a forward leading edge portion (22), and an aft spar portion (23). The forward leading edge and the aft spar portions are connected together as a continuous one-piece tubular member of composite material. The forward leading edge portion (22) may be rounded, and the aft spar portion (23) may include an aft web portion (24) and first and second rebate portions (26, 28). The rebate portions (26, 28) connect the web portion (24) to the rounded forward leading edge portion (22), and provide surfaces for the attachment of skin surface members (16, 18) thereto.

Abstract: A method of manufacturing a shape from a composite material by applying laminations impregnated with plastic resin to a positive mold. At least one cellular, cellular-core layer is applied into the neutral zone of the laminations and embedded into them while the laminations are being built up. The cellular layer is a rigid foam. The cellular-core or honeycomb layer has the axis of each cell radial to that of the shape and can be single, double, or multiple. If double or multiple it may have an interior connective layer consisting of plastic, foil, glass cloth, non-woven carbon-fiber fabric, polyimide, or woven or non-woven fabric impregnated with plastic resin. The cellular-core or honeycomb layer is intended to make the shape more stable and flexurally strong.

Abstract: A rubber roller for spinning whose rubber cot comprises an inner and an outer rubber layer bonded together over a reinforcing layer consisting of a woven cloth or sheeting and fitted securely on the outer periphery of a metal core for roller, without using an adhesive and the manufacturing method thereof.

Abstract: A fishing rod is provided which is formed of a handle having a fishing reel mounting portion, a grip, and a rod body tapered toward its tip. The larger diameter side of the rod body includes a tubular fitting portion having a tapered portion increasing gradually in diameter at a rate of change larger than that of the rod body. The tubular fitting portion is fitted onto the outer periphery of the handle and is coupled integrally therewith. A manufacturing method is also provided for forming the rod body integrally with the tubular fitting portion.

Abstract: A length of material (10) is provided with an indented zone (18) which receives an adhesive layer (24). The outer surface (26) of the adhesive layer (24) is coplanar with the outer surface (12) of the length of material (10) thus providing a check processing tab (44) having a uniform cross sectional configuration. The check processing tabs are wound into rolls (30) and are ultimately adhesively secured to checks (34) with the outer surface (12) of the check processing tab (44) positioned in the same plane as the reverse side (46) of the check (34) and subtantially offset from the face (48) thereof.

Abstract: A double surfaced adhesive tape comprising an elongated strip (14) of flexible material having a longitudinally extending center portion (20) and longitudinally extending first and second edge portions (22, 24). The center portion is thicker than either edge portion, and each edge portion has one adhesively surfaced side (26, 28) and one side (27, 29) that is not surfaced with adhesive. The adhesively surfaced sides may comprise adhesives having different tack properties from one another. The adhesively surfaced sides of the edge portions face in opposite directions from one another.

Abstract: A system for securing the unaffixed tail of a roll product to a convolution thereof underlying the tail with a flexible sealing element wherein a predetermined physical characteristic of the roll product is sensed and an appropriate sealing element such as a label is delivered to the roll product and applied thereto.

Abstract: The web leading edge of a paper roll for a rotary press or the like is held and prevented from raveling by three or more pieces of strong adhesive tape during handling and loading onto a paper feed machine of the printing press. On the paper feed machine, perforated tear lines are formed across the tape pieces by a device comprising a rotary perforating wheel, a mechanism for moving the wheel from one end to the other of the roll and also moving it against and away from all of the tape pieces, and a tape detecting device and a controller for automatically operating the mechanism. The tape pieces can then be easily torn to release the web leading edge immediately prior to web splicing.

Abstract: This invention is directed toward a fiber reinforced resin matrix composite article having fiber reinforced resin matrix bushings. These bushings are formed by tightly wrapping the fibers to form a plug having the fiber orientation from about .+-.20.degree. to about .+-.60.degree. to the central axis around which the fibers are wrapped. The plug is then snugly inserted into a hole which has been cut in the composite article such that the central axis of the plug is perpendicular to the fibers in the composite article. The entire composite article containing the plug is then cured and the plug is then drilled out forming the bushing.

Abstract: Flat pattern equivalents for curved surfaces may be generated by developing a regular network of quadrilateral grid elements resembling a fish net which is mathematically smoothed onto the curved surface. Surface features such as boundaries and cutouts are mapped onto the network. The network is then transformed onto a flat mapping plane to form a grid in a manner analagous to smoothing a fish net mesh onto a flat surface. The surface features are then transformed to the flat surface grid.Individual plies or parts are then cut based upon the flat patterns. The plies or parts will conform to the curved surface exactly.

Abstract: A surface type structural component such as a wing for an aircraft is curved in space and is manufactured from a plurality of fiber wound box frames forming longitudinal and cross ribs made of fiber reinforced resin impregnated material. These box frames are formed as modular units by winding the fiber compound material onto mold bodies and assembling the mold bodies for bonding the box frames together to form a reinforcing grid structure while the box frames are still on the mold bodies. A laminated sheathing is bonded to the grid structure. Methods and apparatus including an automated assembly plant are disclosed for manufacturing the surface type structural component.

Abstract: Non-asbestos elastomeric insulation materials for rocket motors are disclosed. The insulation materials comprise 100 parts by weight of a crosslinked elastomer polymer and between about 10 and 100 (preferably 15-75) parts by weight of an organic fiber selected from cotton flock, Sisal and a combination of cotton flock and Sisal. The insulation materials have notable erosion resistance and can be tailored to have thermal, mechanical and other properties of desired character. The organic fiber advantageously functions as a char forming, low density filler. Other ingredients such as silica, phenolic resin, polybutadiene etc. are included to enhance the utility of the insulation materials.

Abstract: An X-ray transparent and biological inert medical clip for treating aneurisms and the like and process for producing same wherein a graphite reinforced composite film 15, 16, 20 and 21 (FIGS. 1a-1d) is molded into a unitary structure having a pair of "hourglass" like cavities 30, 31 (FIG. 2) hinged together (33) with a pair of jaws 27 and 28 for grasping the aneurism extending from the wall of one cavity and a silicone rubber pellet 35 (FIG. 3) disposed in the other cavity to exert a spring force through the hinge area 33 to normally bias the jaws into contact with each other.

Abstract: This invention provides a rotary heat regenerator which includes a regenerator wheel in which the regenerator matrix is formed of at least one strip of synthetic organic plastic wound onto a central hub, with suitable spacing means being formed in the strip to form gas passages. Inexpensive means is provided to stiffen the wheel to impart lateral strength and rotational stability. In one embodiment of the invention, radial portions of the face of the matrix are fastened together by fusing, by an adhesive, or both. In another embodiment of the invention, radial apertures are formed in the wheel by forcing a heated tool, radially into the wheel periphery so that the surfaces of the strip layers of the matrix are fused together, forming a hollow cylinder bounded by a continuous layer of plastic. To impart further rigidity to the wheel, the hollow cylinder may be filled with a reinforcing rod of plastic or metal.

Abstract: A hose construction and method of making same are provided wherein such hose construction comprises a flexible corrugated hose made of polymeric material, a pair of hose connectors fixed to opposite ends of the hose, and a sleeve disposed around the hose and having opposite end portions wherein the sleeve is fastened to the hose only at its opposite end portions and the sleeve serves to improve the fluid pressure resistance and external wear resistance of the hose while keeping its flexibility substantially intact.

Abstract: A molded synthetic rubber muffler or exhaust component hanger having a molded-in nylon reinforcing loop around the circumferential surface thereof and manufactured according to a method which involves at least the steps of preparing a preform of uncured synthetic rubber which approximates the shape of the finished article, preparing a wrapping loop of synthetic rubber coated nylon the circumferential size of which accurately conforms to the circumferential dimension of the finished article but is slightly greater than the same circumferential dimension of the preform, placing the loop on the preform and compression molding the combination to unite the rubber constituents of each and to expand the preform as to fully fill out the nylon loop.

Abstract: A composite javelin having superior vibration damping characteristics is provided having a hollow or low density body of generally circular cross-section which tapers from small diameter front and rear tip ends to a large diameter more or less in the center, said tapered diameters and general tip and grip features being in conformance with the requirements of the International Olympic Committee. The javelin body can be constructed in either a one or two piece manner and constitutes a plurality of Kevlar.RTM. or fiber glass prepreg bias wound plys forming an underlayer and a plurality of bias wound graphite/epoxy prepreg plys forming an overlayer. In the preferred two piece construction, the distribution of weight and composite center of gravity can be adjusted within the body to allow tuning the javelin to an individual athlete's throwing characteristics.

Abstract: A varied thickness laminate or panel (92, 128) is fabricated by polar winding incomplete lamina or plies (54, 146, 148) on a mandrel (10, 110, 130) at selected angles. The plies (54) are wound at crossing angles, first one layer (60) at one angle and then a second layer (64) at a second angle. At the most remote crossing point from a wide starting end (32), a V (66) is formed between the crossing plies (60, 64) and in the space (62) formed by the V (66), no plies extend on the mandrel side (30). Thus, the winding on each side (30) is incomplete, a space (62) between successive V's (66, 154, 164, 174) being skipped by steps of the crossing plies. The first V (66) starts a taper from wide starting end (32) to narrow other end (34). Successive plies are wound around the mandrel from the polar ends (48, 50, 134), each successive set forming a V so as to thicken the windings in steps formed by the V's.

Abstract: An apparatus for fabricating a container made of foam sheet material. The apparatus includes a mandrel carrying drum that revolves about its longitudinal axis of symmetry. The drum contains a plurality of individual mandrels in radial alignment. Each mandrel revolves about its longitudinal axis as it forms a cylindrically shaped container blank. The drum carries the mandrels in an arcuate path, thus permitting work to be performed on the container blank as it passes a series of work stations.A method of forming a container from foam sheet material is set forth wherein a severed sheet material is attached to a mandrel. The mandrel rotates about its axis to form a cylindrically shaped blank as the mandrel itself is being moved in an arcuate path. While positioned on the mandrel, the container blank is worked upon at a plurality of work stations, thus producing a final container with an end closure which may be apertured.

Abstract: A plurality of lengths of fibers may be disposed into a sheet-like array with the fibers being spaced from each other and defining channels therebetween. A pair of membranes is brought into adhering relation with opposed sides of the fibers of the sheet-like array to form a multichanneled flow device.

Abstract: A composite sports racket frame having a head portion subject to loading is provided with an integral arrangement of resin impregnated braided tow tubes and a layer of tow disposed in wound fashion between part of the braided tows. A method of making a sports racket frame by winding a resin impregnated tow about part of a braided tow tube and placing a second braided tow tube to form an assembly that is internally pressurized and heat cured is disclosed.

Abstract: The invention relates to a method for the manufacture of packing containers. The container body of the packing container is manufactured by spiral winding of a monoaxially molecular-oriented polyester film. The polyester film is spirally wound onto a mandrel to form a tube with the edge zones of successive turns of the strip overlapping in a continuous joint. The material is sealed within the edge zones by means of surface fusion. The invention also relates to a packing container manufactured in accordance with the method.

Abstract: A book cover making process feeds transparent polymer sheet material from a roll of material across a plurality of roller cutting blades for making cuts a portion of the way through the material. The polymer sheet material being fed is coated with adhesive in two space coats on either side of the cut lines on the opposite side of the sheet from the cut lines. The coated adhesive is covered with backing material and the polymer sheet material is then cut into predetermined sizes to form book covers. The coating and backing may be done in one operation and rewound onto a roll and fed from the rewound roll for cutting to size and then have a plurality of lines cut into the individual polymer sheets.

Abstract: A light-weight, high-strength composite pin for use in pin-jointed reciprocating mechanisms and a method of preparation thereof is provided. Basically, the pin has a tubular metal sleeve and an interior fiber-reinforced resin core. At least 50% of the fibers in the core are continuous fibers which are oriented at a predetermined specific angle of orientation ranging, in general, from 0.degree. to about .+-.25.degree.. Indeed, in a preferred embodiment of the present invention, the fibers are cross-plied at an angle of orientation of from about 5.degree. to about 12.degree..

Abstract: In a single-face corrugator of the type in which the corrugated paper is held by suction against the lower corrugated cylinder, the latter includes, outside its inner chamber filled with saturated heating vapor, separate longitudinal channels in the peripheral body of the cylinder. Each channel is connected to the exterior via axial channels and elongate grooves machined in the periphery of the cylinder, and can be connected to a suction apparatus via two hollow and sealed circular arcuate sectors bearing on the part of the face of the cylinder associated with the holding region on the latter. The grooves are staggered and machined in circumferential portions of the periphery of the cylinder so as to extend over several corrugations thereof. An additional blowing sector permits detachment of the corrugated paper.

Abstract: The invention relates to reducing the thermal inertia of furnace or oven walls. Insulating modules under compression are secured to the wall and released from compression upon firing of the furnace.

Abstract: A fabric which is suitable for reinforcing hose structures, particularly railroad air brake hose is provided. The fabric is biased such that the warp and filling yarns intersect at angles between about 87.degree. and 65.degree.. When the biased fabric is used to reinforce a hose structure, one set of yarns is oriented in a circular fashion about the circumference of the hose in order to provide support against expansion of the hose under pressure.

Abstract: An apparatus for sealing the tail of a wound roll of sheet material. A pair of parallel rotatable rollers define a tail separation station and a tail wind-up station that are disposed longitudinally along the length of the rollers A wound roll is positioned at the tail separating station and rotated about its axis. Air jets mounted adjacent the rollers separate the tail from the body of the roll, and the separated tail is supported on an apron that extends laterally from the rollers. After separation of the tail, rotation of the rollers is stopped and the roll with the separated tail is moved longitudinally along the rollers to the wind-up station. A strip of adhesive is applied to the tail from a fixed adhesive head as the tail is moved to the wind-up station. At the wind-up station the roll is rotated to wind the separated tail back onto the body of the roll.

Abstract: A fiber-reinforced composite vehicle wheel, and a method and apparatus for construction thereof. The wheel comprises a disc portion having reinforcing fibers in substantially random orientation disposed predominantly in planes perpendicular to the wheel axis, and a rim portion having directional first reinforcing fibers substantially parallel to each other and oriented circumferentially of or substantially parallel to the wheel axis, or both, and second reinforcing fibers which are substantially randomly oriented circumferentially of the wheel axis. The method includes formation of separate rim and disc charges from sheet molding plastic resin compound and compression molding of the charges to form an integral composite rim and disc structure of essentially homogeneous resin reinforced by the fibers.

Abstract: The invention is a method for the manufacture of hollow bodies, particularly pipes, from fabric reinforced resin by forming a coil of fabric impregnated with resin, which is dried, preheated, and introduced into a preheated mold. The coil is pressed axially into the mold between a preheated borer defining the interior shape of the pipe, and a sleeve, and the resin impregnated in the fabric is polymerized. The product is useful in the manufacture of nozzles for missiles or the like.

Abstract: A tubular fiber reinforced composite shaft is formed (as described) which integrally incorporates a metal sleeve or connection at the end thereof. Initially a metal sleeve having circumferentially spaced recesses on the outer periphery thereof is positioned upon a segment of a mandrel. Fibrous material bearing a non-solidified resinous material is applied around the mandrel and around the recesses in the sleeve. Portions of the previously applied fibrous material bearing the non-solidified resinous material are pressed into the recesses. Additional fibrous material bearing the non-solidified resinous material is applied to the previously applied fibrous material. The resinous material next is solidified to form a tubular composite shaft whereby a secure torsion-transmitting connection is made with the sleeve, and the mandrel is removed.

Abstract: A porous acoustic element is disclosed having a configuration comprised of individual cross-wound porous layers of widely varying porosity, with transition plenum layers interposed therebetween having a configuration so as to prevent formation of blockages and small area openings which would be created by a direct overlay winding of differing pitch. The porosity of each wound layer increases in successive layers to compensate for expansion of the gas as it flows through the element. The resulting porous element allows gaseous flow therethrough, with maximum pressure energy dissipation and controlled velocity to minimize aerodynamic noise created by flow through valves and other flow restrictions. A specific embodiment is disclosed in which the porous layers are created by variable pitch wire ribbon cross windings and the transition layers are provided by wire mesh having relatively large openings.

Abstract: This invention discloses a method and apparatus for forming a tubular sleeve of a shrinkable cellular polymeric material from a predecorated web. Predecorated neck labels are formed from a web having a pair of cross-dimension score lines in precise location to facilitate flat folding. The neck labels preformed from the web are adapted to overlying the neck and closure of a bottle, for example, to provide a tamper-proof feature. Such labels are formed from a web by cutting a presized blank having, if desired, a partial-depth slit along the longitudinal dimension to provide a parting line, winding the blank on a mandrel while successively forming the score lines in precise location, and then overlapping the ends and seaming the same to make a tubular sleeve having precisely-formed sides adapted to uniform flat-folding. The sleeves are stripped from the forming mandrel, flat-folded and packed into tightly-nested stacks for subsequent use.

Abstract: A laminated friction member, such as a clutch facing comprising a friction element comprising aramid fibers and a reinforcing element formed of non-aramid fibers, the elements being impregnated with and bonded together by means of heat-curable cement.

Abstract: An improved simple and cheap method of forming electrode connector for liquid crystal display device has been found. This novel method eliminates difficulties in complicated compression molding process required a high accuracy of dimensions in a molded electrode connector.

Abstract: A cell for coalescing oil droplets dispersed in a water emulsion including an elongated perforated tube core into which the emulsion is injected, layers of oleophilic plastic covered metal mat wound about the core through which the emulsion is forced to pass, the fibers of the metal mat being covered by oleophilic plastic such as vinyl, acrylic, polypropylene, polyethylene, polyvinyl chloride, the metal being in the form of layers of expanded metal or metal fibers, either aluminum or stainless steel. In manufacturing the cell a helix wound wire is formed around the cylindrical plastic coated metal to retain it in place and resist pressure drop of fluid flowing through the metal fibers. In addition, the preferred arrangement includes the use of an outer sleeve formed of a mat of fibrous material such as polyester fibers, acrylic fibers, modacrylic fibers and mixtures thereof.

Abstract: Two coaxial metal pipes, whose confronting extremities are each provided with a plurality of peripheral ribs of staggered height separated by two or more peripheral grooves, are interconnected by a coupling sleeve of fiber-reinforced thermosetting resin subdivided into several coaxially interleaved and independently deformable cylindrical shells each terminating in a pair of internal beads engaged in a respective peripheral pipe groove. The shells, increasing in axial tensile strength from the innermost to the outermost one, are preferably separated from one another by interposed antibonding layers of thermoplastic resin. A resinous filler can be inserted between the pipe extremities for electrically insulating them from each other. The shells of the coupling sleeve can be formed by coiling resin-coated filaments around the pipe axis, advantageously with application of an antifriction layer on each inner shell before the thermosetting material thereof has been fully hardened.

Abstract: A profiled vehicle wheel rim is manufactured by spirally winding a continuous strip of ductile sheet metal onto a profiled former, with an adhesive interposed between the turns, under forces which deform the strip from the flat state to adopt the shape of the former. In a preferred construction a disc for the wheel is interposed between two axially separable parts of the former so that the windings bend down over the axial extremities of the periphery of the disc, thus entrapping it in an annular channel of the formed rim.

Abstract: A tubular fiber reinforced composite shaft is formed (as described) which integrally incorporates a metal sleeve or connection at the end thereof. Initially a metal sleeve having circumferentially spaced recesses on the outer periphery thereof is positioned upon a segment of a mandrel. Fibrous material bearing a non-solidified resinous material is applied around the mandrel and around the recesses in the sleeve. Portions of the previously applied fibrous material bearing the non-solidified resinous material are pressed into the recesses. Additional fibrous material bearing the non-solidified resinous material is applied to the previously applied fibrous material. The resinous material next is solidified to form a tubular composite shaft whereby a secure torsion-transmitting connection is made with the sleeve, and the mandrel is removed.

Abstract: A tennis racket frame is constructed primarily of an elongated hollow tube member having a wall thereof consisting essentially of a plurality of concentric layers of high tensile strength fibers impregnated and bonded together by binder resin, at least two of the layers being helical windings of opposite unidirectional hands, and the head portion of a racket frame having a groove molded therein to receive the loop portions of the strings in recessed relation to the surrounding surface areas of the frame. The frames are made by a method including the use of a special mandrel on which the layers of fiber are wound under controlled conditions providing extra material in the head portion which is formed into the wall of the grooved portion of the head without affecting the overall sectional dimensions of the frame.

Abstract: A high-pressure joint tester includes a pair (or two pairs) of plugs, each plug having an annular rigid channel containing an inflatable elastomeric annular tube. The spaced, parallel plugs are joined together by a rigid cylindrical wall extending between inner sides of the channels. The tubes are inflated at preselected pressures to seal against interior pipe walls on opposite sides of a locus where two pipe ends meet at a joint, and fluid is introduced under pressure through the cylindrical wall to the outer surface thereof. Rollers support the device for movement through the pipeline to be tested.