JPS6367419A - Connector member - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates primarily to fastener members, and more particularly to reinforced fiber composite fasteners and methods of manufacturing the same.

BACKGROUND OF THE INVENTION Over the past few years, it has become desirable to provide high strength non-metallic fasteners. Such fasteners have considerable advantages since plastic components secured with metal fasteners are susceptible to deterioration due to galvanic corrosion and differences in coefficients of thermal expansion. Additionally, the use of metal fasteners in aircraft and other such applications can create problems with navigation equipment deflection and electronics.

However, currently known non-metallic fastening devices generally
The low strength of the bracket is both very evident in threaded or thread-like areas, without the significantly greater strength exhibited by metal fasteners. When axial forces are applied to mating, threaded members, such as nuts and bolts, the threads of the members are subjected to shear forces that can distort or otherwise damage the threads. Similarly, when an axial force is applied to the enlarged head portion of a bolt, the axial force required to sufficiently secure the fastened member will cause the fastener to move transversely beyond the axis of the fastener. Even the load support extending in the direction may be weakened by the flange.

To withstand such shear forces, the threaded plastic member includes resin-impregnated fibers. For example, the glass fiber is helically wound around the longitudinal axis of the fastener, ie in the longitudinal direction of the thread. In this case, for the shear force on the thread,
Primarily, the resin adhesion between the fibers is opposed. Since the shear stress of the resin is generally lower than that of the resin-impregnated fiber, the strength of the component is never sufficient, primarily due to the two-dimensional fiber orientation which is inevitably subject to delamination.

Other methods that have been used to increase the shear strength of threads include using mat reinforcement around protruding unidirectional fiber rods.

Matte reinforcement exhibits random fiber orientation with multidirectional characteristics, but because the fibers are not continuous, they continue to tend toward delamination and relatively low strength.

U.S. Pat. No. 2,510,693 describes an anchoring member having a longitudinal fiber reinforcement media extending along the stem portion of the fastener and into the head. U.S. Pat. No. 2,685.813 describes a fiberglass rivet body that includes helically wound longitudinal fibers, and in an alternative embodiment, the longitudinal fibers are essentially Helically, it is surrounded by a mesh of threads.

U.S. Pat. No. 2,928.764 and 3,
No. 283.050 discloses a method and apparatus for manufacturing threaded fiber fasteners that use circumferential or helical fibers to form the threads. U.S. Patent Nos. 2,943.967 and 4. No. 063.838 also details the formation of threaded members that combine longitudinal and helical fibers or filaments.

U.S. Pat. No. 3,995,092 details the use of a plurality of layered sections laminate together to form a fastening device, the laminations being substantially perpendicular to the surface of a threaded shaft. It is. U.S. Pat. No. 3,495,494 also teaches the use of longitudinal and helically bent fibers oriented along a generally tortuous path to substantially match the course of the threads. It is detailed.

SUMMARY OF THE INVENTION In accordance with the present invention, a fastener member is formed from a three-dimensional orthogonal block molded from a multidimensional single organic matrix woven fiber preform, such as an organic resin, with uniform isotropic properties. Thus, the fastener and the threads thereon include a plurality of fibers disposed sequentially through the fastener. Specifically, the fiber is
arranged in a plane essentially perpendicular to the longitudinal axis of the fastening device, i.e. as a chord in the cross-section of the fastening device, the end portions of such layered fibers consist of the threads of the fastening device and the other Extends to angular load bearing flange.

For example, the fibers are disposed at right angles to the plane of the transverse cross section of the fastener, such that the end portions of the fibers form the ridges and valleys of the thread. Such fasteners have increased shear strength and resist delamination as a result of the continuous three-dimensional fiber arrangement. Additionally, by using preformed and impregnated blocks, fastener members can be manufactured economically and advantageously without the need for complex winding or casting machinery or techniques.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed illustrated embodiment of the invention is disclosed herein. However, it is to be understood that this embodiment is merely illustrative of the invention and that it may take forms that differ from the disclosed description.

Therefore, the specific details are not necessarily to be construed as limiting, but rather as forming the basis of the claims defining the scope of the invention.

The three-dimensional post-joint fastener member is formed by using a multidimensional, single organic matrix woven fiber preform impregnated with a thermoset or thermoplastic organic resin. The fiber used can be selected according to the desired properties and the manner in which the fastening device has to be used, for example fiberglass, Kevl
AR, graphite, or carbon fiber may be used. The filament is spun 12
Thread fibers ranging from K (coarse) to IK (fine) are preferred, with threads in the middle of about 6 being believed to provide excellent properties for most general applications.

The resin system may also be varied according to desired strength, temperature, and environmental requirements. Polyester, epoxy, phenolic, polyimide and bismaleimide resins have proven suitable. Thermoplastic resins such as polyphenylene sulfide (PPS) or PEEK may be used if post-molding is desired. In the preferred embodiment described herein, the National Starch Chemical Company (Nat.
lonal 5tarch and cheilcal
Termid (Thcra+1d) MC, a polyimide resin marketed by
-600 is used for its superior strength, low moisture absorption, and excellent properties especially in high temperature applications.

The woven preforms described below were manufactured by Bedford, Inc., Massachusetts.
) fiber materials and East Roches, New Hampshire
ter )'s Techn I wea
ve). In the preferred embodiment described here, the preform has a fiber center-to-center spacing of approximately 0.05 inches on all axes (x, y, and 2
) and a fiber content of 40% to 50% of the preform. Generally, fiber content is a prominent characteristic in the preform specification, and fiber spacing is determined by that amount and yarn type. At fiber amounts less than about 35%, the properties of the fastener, especially the strength, begin to decline due to the fact that the fibers are the load-bearing components of such composites. At fiber contents greater than 50%, the preform becomes difficult to completely impregnate with resin, resulting in a "resin-dry" composite, i.e., containing resin-free voids or bubbles dispersed through them. Compounds result.

Therefore, a fiber content of 40% to 50% provides excellent strength to most resins.

The single organic matrix woven preform is impregnated with a suitable resin and preferably at pressure and temperature where it is cured as required. Impregnation may be carried out by various methods depending on the viscosity of the resin used, but
Most commonly, it is preferred to immerse the preform in a resin solution, ie, the resin has been diluted with a suitable solvent to aid in dispersion of the resin. If possible, it is desirable to heat the resin and solvent mixture or preform to a temperature sufficient to aid in dispersion of the resin and solvent. For example, in thermoset resins, such as polyimide resins, which are specifically discussed below, the preform may be immersed in a resin solution that is heated to a temperature of about 350°F, such temperature being below the boiling point of the solvent. The temperature is below the curing temperature of the resin.

After impregnation, the solvent added to the resin must be removed to avoid solvent release if higher temperatures are applied during the curing process.

Thus, the impregnated preform is heated below both the boiling point of the solvent and the curing temperature of the resin for a sufficient period of time to allow solvent vapor to escape. To minimize the formation of voids or bubbles within the composite, it is preferred to compress the impregnated preform once the resin begins to cure. Such compression molding is known in the art and is generally accomplished by using a hydraulic press, where the preform is compressed between metal plates that are coated with a mold release compound.

With a given resin, once the resin begins to cure, pressure is applied to the composite to avoid deforming the composite. This gel point can be ascertained by a number of methods. For example, the gel time of the resin may be predetermined, or the uncured resin cured under conditions similar to a molding press may be observed to indicate the onset of the curing process.

However, these methods are speculative in nature and are therefore subject to some degree of error.

Therefore, the gelling time can be determined by feedback through the press, i.e. by the operator of the press by sensing the movement of the platen with respect to the increase in pressure, or by a microprocessor-controlled closed-loop system with an automated feedback circuit, such as the Pasadena, Calif. Inc, of' Pa5ade
Pasadena Hydraulics (Na)
l1ydraul! Preferably, it is determined either by using those commercially available from ES). Such systems measure the resistance due to slight platen movement, and as soon as the resistance increases indicating that curing has begun, the pressure is increased to that required for compression molding. Ru.

For example, for the polyimide resin used in the specific examples below, the thermoset resin, or the preform impregnated with it, is heated in a molding press to a temperature of 490° F., the curing temperature of the resin. During this initial heating process, "contact" pressure (10 to 50 psi) is used. This pressure is also applied during the preheating process and is then flash-relaxed or "buffered" so that the remaining solvent can escape and the "contact" pressure is then applied again. At this point, a light pressure of just over 50 psi is used until either the operator or the feedback circuit detects that the resin is beginning to cure. Then the pressure is 500
to 1000 psi, the preferred pressure being:
Approximately 600 to 700 psi.

This pressure is maintained until the resin has completely cured. After curing, no further pressure is required, but it is preferable to maintain the high temperatures used in the compression molding process to increase the strength of fasteners expected to be used in high temperature environments.

Such post-cure techniques are known in the art for certain resins and include Thera+id MC-600
A preferred technique for post-curing is described below in which the temperature is increased incrementally from the curing temperature of the incremental step and held at 700''F for about 4 hours.

Regarding the specific fastening devices described and tested below:
Carbon fiber (Union Carbide (Llnlon)
Carblde) T-3006K), 0°0
A single organic matrix woven preform with a center-to-center fiber distance of 5 inches and a total fiber content of 50% was used. Polyimide resin (Thcrmid
MC-600) is a mixture of 2 parts of NMP (N-methylpyrrolidone, 1-methyl-2-pyrrolidinone) by weight.
-600 and 350°
Prepared by heating to F. The woven preform was dipped into the resin and solvent mixture and thus impregnated. After impregnation, the NMP was driven off by heating (300° F.) in a circulating air oven until the impregnated preform had a heat loss of about 2% to 3% by weight. Generally, the time in the oven is about 1 hour. However, if the circulating air oven does not sufficiently release the solvent, a temperature of 300 to 325 degrees Fahrenheit and a pressure of 25 to 30 inches of mercury may be used to facilitate the release of the solvent.

After the solvent has so evaporated, the preform is 485
Molded between platens at °F. Regarding this point, T.
It must be noted that the gel time of herIlld MC-600 is approximately 90 seconds.

The preform was then placed between the platens of a hydraulic press at a temperature of 495° F. and a pressure of approximately 20 psi was applied for 30 seconds. The pressure was then released for 2.3 seconds, followed by 20 pounds of pressure for approximately 1 minute. After that, when the resin starts to gel, 650 ps
i pressure was applied.

The preform was heated to 48 psi at a pressure of 600-700 ps i.
Cured at 5°F for approximately 1 hour.

The cured preform is then cooled under pressure to below 300 degrees Fahrenheit until the pressure is relieved. next,
The block was post-cured in an oven at a temperature ramp of approximately 1°F per minute to 600"F and left at this temperature for about an hour. Thereafter, the temperature was again ramped to 700"F per minute. The temperature was increased by 1° F. and maintained for approximately 4 hours.

Cooling is then initiated at a rate of approximately 2°F per minute, and once cooled to room temperature, the block, as described,
Can be cut immediately.

Blocks thus formed may be ground on precision lathes commonly used to grind fasteners.

However, when the fibers and resins described herein are used, a pulverizing wheel is preferred and
Carbide or diamond grinding wheels with a grain size of from 120 to 120 are preferred. Typical grinding speed is 1/
/2 inch diameter grinding wheel is approximately 3000 revolutions per minute.

The speed of rotation and movement of the lathe must be relatively low to keep the grinding pressure low. It will be appreciated that the powder and dust generated during such grinding must be collected in a vacuum system.

FIG. 1 shows the three-dimensional arrangement of fibers in a single organic matrix woven preform of the preferred embodiment;
It should be understood that other types of multidimensional weaves may be used as required by the particular application. This drawing shows a plurality of fibers 12 disposed along the X-axis, a second plurality 14 of fibers disposed along the X-axis, and a third plurality of fibers 16 disposed along the Z-axis. A woven preform 10 is shown comprising.

Each of the plurality of fibers 12.14 and 16 has a 90°
It can be seen that it is placed at an angle of .

A fiber center-to-center spacing of approximately 0.05 inches provides preform 10 with a 40% to 50% fiber content.

Preform 10 is impregnated with a curable resin as described above to form a block from which fastener members are cut.

Referring to FIG. 2, a bolt 20 is shown cut from a preform 10 impregnated with a single organic matrix. Bolt 20 is seen to include a shank 22 that includes a threaded portion 24 . At the opposite end of the threaded portion 24, the bolt 20 has a bearing surface 28 and a slot 3 for the insertion of a turning tool, such as a driver, not specifically shown.
It is seen to include an enlarged head portion 26 including 0.

Referring to FIGS. 3 and 4, cross-sectional views of bolt 20 will be described. It should be noted that in these figures bolt 20 includes a plurality of fibers, designated by reference numeral 32 and disposed at right angles to the fibers designated by reference numeral 34. Each of the plurality of fibers 32 and 34 is also disposed at 90° with the plurality of fibers 36, which fibers are oriented axially with respect to the shank 22.

Referring to FIG. 5, nut 40 is shown.

Nut 40 is formed from the same single organic matrix resin impregnated composite fiber block as described for bolt 20 and is seen to include fibers 42, 44 and 46. Nut 40 is seen to include an aperture 48 with internal threads 50 adapted to matingly engage threaded portion 24 of bolt 20 .

As shown in FIG. 6, a two-dimensional composite panel 60 is seen overlapping a similar panel 62. As shown in FIG. panel 60
and 62 are respectively fibers 64, 66.6
It is seen to be formed from 8 and 70. panel 60
and 62 are seen drilled to form an aperture 2 through which a bolt 74 is obtained. Bolts 74 are seen to cooperate with washers 76 and 78 and nuts 80 to secure panels 60 and 62. Because panels 60 and 62 do not have a vertical fiber orientation to resist vertical compressive forces, the higher compressive bearing stresses imparted by using three-dimensional composite fasteners may not be sufficient to damage panels 60 and 62. can. Therefore, the three-dimensional composite bushing 82 is connected to the fixed composite panels 60 and 62.
Provision is made so that higher fastener compressive bearing stresses can be applied without damage to the bearing. Bushing 82 also separates fastener 74 from aperture 2 and protects the two-dimensional component from delamination during insertion of the fastener.

As shown in FIG. 7, bushing 82 is formed from a woven preform impregnated with a single organic matrix resin in a manner similar to that described for fastener 20 by grinding means known in the art. 10 and includes an axial fiber 84 and transverse fibers 86 and 88.

The fastener members of the present invention have significant shear strength advantages because the three-dimensional reinforcing fibers extend laterally and continuously along the three dimensions of the fastener member. In a particular example, as explained above, 10-3
2 A 3/16 inch diameter fastener with a UNJF-3A threaded shank was cut into an existing metal fastener design as shown in FIG. The test results showed that the shear strength through the shank was 31 per square inch.
．． 000 bond. When tested in tension with a load applied through the head and the nut tightened onto the screw, the fastener design failed by shearing the collar from the shank without damaging the threads. This shear strength value is comparable to that provided by metal fasteners of similar design.

Although the preferred embodiments described herein are for threaded fasteners, fasteners such as pins, washers, collars, studs, rivets, and other cylindrical fasteners are within the scope of this invention. , the scope of which is limited by the following claims.

[Brief explanation of drawings]

FIG. 1 is a perspective schematic diagram of a three-dimensional orthogonal weave of a fiber preform used in the present invention. FIG. 2 is a side view of a fastening device member according to the invention. FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 5 is a perspective view of a fastener member adapted to matingly engage the fastener shown in FIG. 2; FIG. Figure 6 shows a three-dimensional post-joint fastening device used in bushings.
Figure 3 shows a side view, partially in section. FIG. 7 shows a perspective view of the bushing of FIG. 6. In the figure, 10 is a woven preform, 12° 14.
16.32.34.36, 42, 44, 46.64.6
6. 68 and 70 are fibers, 20 and 74 are bolts, 22 is a shank, 24 is a threaded portion, 26 is a head portion, 28 is a bearing surface, 30 is a slot, 40 is a nut, 4
8 and 72 are apertures, 50 are threads, 60 and 62 are panels, 76 and 78 are washers, 84 is a bush,
84 is an axial fiber, and 86 and 88 are transverse fibers. □14 FIG, 1 -7＼FIG, 2 FIG, 3 FIG, 4 FIG, 5

Claims (10)

[Claims] (1) a first plurality of unitary organic fastener members having at least one laterally integral load-bearing flange and extending continuously along a longitudinal axis therethrough; a second plurality of single organic matrix resin-impregnated fibers disposed laterally at right angles to the first plurality of fibers, and a first plurality of single organic matrix resin-impregnated fibers;
and a third plurality of single organic matrix resin-impregnated fibers disposed laterally at right angles to each of the second plurality of fibers; A fastener member, at least a portion of which extends continuously across a cross-section of the fastener to form a load bearing flange. (2) The fastening device member according to claim 1, wherein the flange has a spiral thread on the surface of the fastening member. 3. The fastener member of claim 2 further comprising a shank and an enlarged head portion, the threads being disposed on an outer surface of the shank. (4) The fastening device is hollow and the thread is continuous and disposed on its inner surface.
Fastening device as described in section. (5) the fastening device includes a longitudinal shank, and the load-bearing flange includes helical threads on the outer surface of the shank, and the second and third plurality of resin-impregnated fibers extend across the cross-section. 2. A fastener member as claimed in claim 1, extending continuously and transversely to the thread. (6) The fastener member of claim 1 or 5, wherein the load flange further comprises a head portion including a workpiece abutting surface. (7) A fastener member having a longitudinal shank including an external threaded portion at a first end and an enlarged portion at an end opposite the threaded portion, the members each being perpendicular to each other. a plurality of single organic matrix resin-impregnated fibers disposed in first, second, and third planes, the fibers in the first plane having an opposite end from a first end; A fastener member that extends continuously and longitudinally and wherein the fibers of the second and third planes extend continuously between laterally opposing surfaces of the fastener member. (8) A fastening device comprising a hollow member having an interior surface thereon and a continuous integral thread, the fastening device having first, second and third portions each perpendicular to one another;
characterized by comprising a plurality of single organic matrix resin-impregnated fibers disposed in a plane, the fibers in the first plane extending continuously along the axis of the hollow member;
and a third plane of fibers extending between the threads and the outer surface of the fastener. (9) An improvement in a method of manufacturing a fastening device having continuous helical threads comprising the step of forming an essentially void-free block of a single organic matrix resin-impregnated fiber. So, the fiber is
woven to form first, second and third planes, each perpendicular to one another, and wherein the fibers of the first plane extend continuously along the longitudinal axis of the fastener, and the fibers of the first plane extend continuously along the longitudinal axis of the fastener;
An improvement further comprising the step of grinding the fastener from the block in such a manner that the planar fibers form the ridges and valleys of a helical thread. (10) The fastening device is a bolt member having a shank portion, an external thread portion at a first end, and an enlarged head portion at an end opposite the thread portion; 9. The fibers extend continuously from the enlarged head portion to the threaded portion, and the fibers of the second and third planes extend continuously across the enlarged head portion. methods and improvements.