CN1041015C - Composite reinforcing tape of high tensile strength and methods of making and using same - Google Patents

Abstract

A spiral belt having a plurality of turns of a high tensile strength composite is made by the steps of; feeding a plurality of continuous high tensile strength fibers through uncured resin to form a ribbon; attaching the flat tape to an adhesive tape having at least one substantially flat surface to form a laminated tape; winding the laminate strip around a mandrel to form a plurality of stacked turns; curing the resin within the composite tape to form each convolution into a helical shape; the release tape is then peeled from the composite tape. The helical band of the method has a substantially flat surface and an elastic memory. Such a tape may be used to wrap around a reinforcing axially extending structure having radially outward internal forces and to hold the turns of the tape in place with an adhesive layer during wrapping.

Description

Composite reinforcing tape of high tensile strength and methods of making and using same

The invention relates to the field of composite materials. More specifically, the present invention relates to a reinforcement strip in the form of a helix made of composite material and a method for its manufacture.

Extensive piping systems are used to transport gases or liquids under pressure over long distances. These pipes can corrode and, in some cases, cracks that develop along the pipe axis due to high speeds and forces can cause the pipes to fail. Over the years, a number of methods have been used to repair corroded sections of pipelines and to limit the propagation of plastic and brittle failures in such pipelines. One method involves wrapping the pipe with a coiled tape made of a high tensile strength composite material. Published Canadian Patent Application No. 2,028,254 describes the use of these composite tapes to repair and strengthen pipes, while US Patent No. 4,700,752 describes the use of these composite tapes to arrest cracks to limit the propagation of plastic failure in pipes. The disclosures in these two documents are hereby incorporated by reference.

The composite tapes employed in the above methods consist of continuous fibers of high tensile strength material encapsulated within a resin matrix. The methods hitherto employed for the manufacture of these composite tapes suffer from various disadvantages. In one such method, high tensile strength fibers are formed in a ribbon having a plurality of transverse filaments holding the fibers together, the transverse filaments being held in place by strips of hot melt adhesive. One difficulty associated with the use of such tapes is the inability to uniformly wrap and encapsulate the fibers with a resin coating. Another problem with methods using these strips is that the heat associated with the gelling and curing of the resin can melt the hot melt adhesive strips, leaving many voids across the composite tape. These voids act as channels that allow water to penetrate and attack the fibers, weakening the composite tape over time.

In order to overcome some of these difficulties, the inventors of the present invention have experimented with the use of individual fibers not connected by transverse filaments. However, experimental methods using individual fibers that have been attempted to date have produced composite tapes with undulating inner and outer surfaces. That is, during the manufacturing process, tension within the continuous fibers has caused these composite tapes to have on each surface a random series of peaks and valleys extending along the length of the composite tape. The bees and valleys on adjacent coiled turns of the composite tape can interfere with each other when trying to align the turns radially during installation, thereby making the installation process more difficult.

Another issue associated with these experimentally produced composite tapes relates to the intended function of the composite tape as a structural reinforcement. Typically, in installations where the composite tape is wrapped around, for example, a pipe, adhesive is applied between adjacent turns of the composite tape as it is wound onto the pipe. The adhesive is used to prevent the twisted composite tape from unraveling under the very high fluid pressures that these pipes normally operate under. However, some problems associated with the use of these adhesives have been encountered with these composite tapes which have been wound onto simulated pipes for testing purposes. These problems include the difficulty of consistently developing sufficient bond strength between adjacent turns of the composite tape and the difficulty of achieving a sufficiently rapid and consistent adhesive cure rate. Another problem is the inability to obtain a very thin and uniform layer of adhesive to minimize the "cushion" effect caused by the adhesive layer between adjacent turns of the composite tape.

Therefore, there is a need for improved processes for manufacturing high tensile strength composite tapes by encapsulating continuous high tensile strength fibers within a resin matrix. There is also a need for a method of regularly forming strong bonds between adjacent turns of composite tapes as they are wound to reinforce a structure.

It is these needs that the present invention addresses.

It has been found that the uneven bond strength between the turns of the experimental composite tapes using individual fibers is not caused by the adhesive applied during the winding of these composite tapes into a structure, but by the It is caused by the uneven surface formed during fabrication. When the composite tape is wound, the peaks and valleys on two adjacent layers may align differently. In one case, the opposing surfaces of two adjacent layers are "in phase", ie the peaks on one layer mesh into the valleys on the adjacent layer so that continuous contact is formed between the opposing surfaces of the two layers. In another case, the two surfaces are "out of phase", that is, the peaks on one layer are aligned with the peaks on the adjacent layer, so that the opposing surfaces of the two layers only touch each other at the peaks, but not around the valleys. There is a large distance between the two surfaces. Since the peaks and valleys are randomly distributed on each layer, it is nearly impossible for all peaks and valleys on one surface to be in or out of phase with all peaks and valleys on the opposite surface. The most likely state is that some peaks and valleys on opposing surfaces are in phase, others are out of phase, and some are in between completely in phase or completely out of phase.

Since the bonding strength is inversely proportional to the thickness of the adhesive layer, the bonding strength between two adjacent turns of the composite tape depends largely on the distance between the opposite surfaces of the two adjacent turns. The closer the two opposite surfaces are to each other, the greater the bond strength; the farther the two opposite surfaces are apart, the smaller the bond strength. By practicing the method of the present invention, composite tapes employing individual fibers can now be produced with flat surfaces such that two adjacent turns of the composite tape are in substantially continuous contact with each other over the entire surface. As a result, these composite tapes can now be consistently wound with a thin layer of adhesive of uniform thickness between adjacent turns, thereby achieving high bond strengths. These thin layers of adhesive also allow for a consistently rapid adhesive cure rate and greatly reduce the cushioning effect that would result from applying adhesive between adjacent turns of the composite tape. Also, the elimination of peaks and valleys from these composite tapes makes it easier to radially align multiple turns of the composite tape during the winding process.

Another benefit of the process of the present invention is that the high tensile strength fibers can now be uniformly and fully coated and sealed within the resin body without forming any voids or channels within the composite tape. The resin thus acts to protect the fibers embedded in it from possible mechanical and chemical damage when exposed to the environment. Furthermore, the process used in the present invention produces high quality composite tapes with greater fiber encapsulation, which results in super strong composites.

One aspect of the present invention provides a method of making a helical ribbon of multi-turn high tensile strength composite material. A method according to this aspect of the invention includes the step of passing a plurality of continuous high tensile strength fibers through a bath of resin in an uncured fluid state so that the individual fibers are completely coated with resin and bond together to form a composite Material webbing. The composite webbing is applied to the semi-rigid barrier tape having at least one flat surface such that at least one surface of the webbing is in intimate contact with the barrier tape to form a laminated tape. The laminated tape is wound on a mandrel so that the composite material is formed into a plurality of superimposed coils, the resin within the tape at least partially cured to a solid state to define the coils into a helical configuration. When the adhesive barrier tape is peeled from the composite webbing, a composite webbing having at least one substantially flat surface is seen.

Preferably, the tape is rigid enough so that at least one planar surface of the tape will not be deformed by the fibers in the composite tape during the winding and curing steps, but the tape should be sufficiently rigid. Soft so that it wraps evenly around the mandrel during the winding step. The barrier tape may have at least two substantially planar surfaces such that the first and second sides of the composite tape in each of the plurality of laminated turns are in contact with one planar surface of the barrier tape. While the rigidity of the tape will depend largely on the particular material from which the tape is constructed, it is preferred that the tape be at least about 0.005 inches thick. While the tape can be made of any film material of suitable rigidity, polypropylene, nylon, and mylar tapes are particularly preferred.

The high tensile strength fibers used to make composites are preferably constructed of non-metallic, non-conductive materials. For example, the fibers may be glass fibers, preferably E-glass fibers. Most desirably, the fibers are individual fibers having a diameter of no more than about 0.001 inch. The term "individual" as used herein means that the individual fibers are independent of each other without any transverse filaments or other connecting elements which might hold the fibers together. The fibers may be in the form of fiber bundles, each fiber bundle comprising a plurality of individual fibers. In this case, it is desirable for each fiber tow to pass around a set of spreading rods to spread out the individual fibers within each fiber tow before entering the resin bath.

The resins of which the composite material is composed are preferably elastic in the cured solid state and may be selected from the group consisting of polyester resins, vinyl ester resins, polyurethane resins, epoxy resins, asphalt enamel, coal tar enamel, and similar materials . Among these resins, polyester resins, vinyl ester resins, polyurethane resins and epoxy resins are preferable, and isophthalic polyester resins are particularly preferable. A preferred composite material comprises between about 50% and 90% by weight fibers and between about 10% and 50% by weight resin; more preferably between about 65% and about 75% by weight fibers and about 25% by weight % to about 35% by weight resin; most preferably about 70% by weight fiber and about 30% by weight resin.

The step of feeding the fibers into the resin bath may include a step of passing the fibers under a rod in the resin so that they abruptly change direction of travel so that the fibers in the tow are further dispersed and further separated from each other. Separate so that they are completely coated with resin. Fibers can be tensioned before being fed through the resin bath. Tensioning can be achieved by passing the fiber around a set of breakaway rods to apply a pulling force to the forward movement of the fiber entering the resin bath. The process described above provides a simple and efficient method for producing composite tapes in helical form with high tensile strength in the helical direction.

Another aspect of the invention provides a method of strengthening an axially extending structure against internal forces radially outward from the interior of the structure. A method according to this aspect of the invention includes a step of providing a helical ribbon having a plurality of turns of high tensile strength composite material, each turn having at least one substantially flat surface. The turns of the helical ribbon are wrapped around the structure with an adhesive such that the turns do not move relative to each other or the structure.

A more complete understanding of the present subject matter and its various advantages may be obtained by referring to the following detailed description taken in conjunction with the accompanying drawings.

Fig. 1 a is the enlarged schematic cross-sectional view taken by cutting two adjacent turns of the experimental helical band in a winding position;

Fig. 2 is the magnified schematic cross-sectional view that two adjacent circles of the helical band of the present invention are cut through;

Fig. 3 is the main figure of spiral band;

Fig. 4 is the schematic diagram showing the spiral ribbon production process method of an embodiment of the present invention;

Figure 5 is an enlarged cut-away sectional view schematically showing adjacent turns of the helical ribbon in the process of manufacture;

FIG. 6 is a schematic cutaway view showing a spiral ribbon winding process according to another embodiment of the present invention;

Figure 7 is a cutaway front view of a structure reinforced with a helical band of an embodiment of the present invention;

Fig. 8 is a schematic cross-sectional view along line A-A in Fig. 7;

Figure 9 is a partially schematic front view of a structure to which a plurality of helical ribbons of the present invention have been wound for reinforcement. Several helical bands were partially excised;

Figure 10 is a cutaway front view of a structure on which a plurality of helical ribbons of the present invention have been wound for reinforcement according to another embodiment of the present invention.

The process of the present invention utilizes continuous fibers made of lightweight high tensile strength material. Non-metallic, non-conductive fibers are generally preferred, although fibers made of any high tensile strength material may be used. From this point of view, glass fibers are preferred, and E-glass fibers are particularly preferred because of their lower cost. However, the present invention contemplates the use of fibers made from other high tensile strength materials, such as S-glass fibers, R-glass fibers, and Kevlar. Fibers are provided as individual fibers. That is, the fibers do not include any transverse filaments, any hot melt glue, or any other connectors that might hold some fibers together. Desirably, each individual fiber is no more than 0.001 inches in diameter. Fibers may be provided in bundles, each bundle being independent of nearby fibers and comprising hundreds or even thousands of individual fibers.

Referring to Fig. 4, a plurality of fiber bundles 10 are pulled out from the package (not shown) by a guide device 12, and the guide device 12 has a plurality of feeding holes 13, and the feeding holes 13 guide the fiber bundles 10, like this, They are not entangled with each other and are aligned substantially in the same direction for subsequent processing. The number of fiber bundles 10 provided depends on the width and thickness of the helical ribbon to be produced and the desired fiber/resin ratio within the ribbon.

The tow 10 is drawn from a guide 12 through a bath 14 containing a resin 16 . Several criteria must be considered in selecting a suitable resin for use in the present invention. A suitable resin is preferably in an uncured state where it is sufficiently flowable to completely coat the individual fibers in tow 10, yet viscous enough to fill and remain in place. in the spaces between the fibers. Preferably, the resin also achieves a solid state that exhibits an elastic memory. By adjusting the amount of catalyst added to the resin, the time required for the resin to solidify can be controlled so that the various forming steps described below can be performed while the resin is still in an uncured fluid state.

Another factor to consider in resin selection is the ability of the resin in its cured state to protect the embedded fibers from chemical and mechanical damage. In this regard, when reinforcing a structure with helical tapes of composite material, the fibers within the helical tapes are generally the main load-carrying elements. Accordingly, the resin in its cured state preferably has sufficient strength and resistance to damage by moisture, soil chemistry, and other environmental effects to prevent damage or weakening of the fibers.

At the same time, it is preferable to use a resin whose ductility and elongation can be coordinated with the fiber in the cured state. If the ductility and elongation of the fibers and the resin are significantly different, the tensile stress applied to the helical tape when used as a reinforcement will generate a shear force at the interface between the fibers and the resin, which will destroy the Interfacial bonding between these two components. When the bond is broken, aggressive media such as acid and alkali in the air and soil will quickly invade along the fibers to destroy and weaken it. By making the ductility and elongation of the resin as close as possible to that of the fiber, the shear force at the interface is minimized, thereby reducing the possibility of debonding between the resin and the fiber.

Suitable resins for use in the present invention may be selected from the group consisting of polyester resins, vinyl ester resins, polyurethane resins, epoxy resins, bituminous enamel and coal tar enamel, considering the above criteria. Among these materials, polyester resins, vinyl ester resins, polyurethane resins, and epoxy resins are preferable. Other materials with properties similar to those described above and meeting the above requirements may also be used. A particularly preferred resin is a isophthalic polyester resin consisting of the isophthalic polyester benzene component and a methyl ethyl ketone peroxide catalyst used to gel and cure the resin to a solid state. In addition to this catalyst, various conventional ingredients can also be added to the resin to obtain the desired special properties. These additives include, for example, protectants to protect the resin from UV damage, tack control agents, pigments to color the resin for visibility or identification purposes, and the like.

The fiber bundle 10 may be fed through a set of spreading or redirecting rods 18 before passing through the guide mechanism 12 . A rod set 18 comprises three rods 20 , 22 and 24 spaced from one another in the horizontal plane, one set of rods 18 for each row of feed holes 13 of the guide 12 . Thus, a group of tows 10 can be pulled over the rods 20 in the uppermost rod set 18 , under the rods 22 and over the rods 24 and then through the top row of feed holes 13 of the guide 12 . The remaining fiber bundles 10 are similarly drawn around the rods 20 , 22 and 24 of the remaining rod group rods 18 and then through the rows of feed holes 13 . The change rod 18 serves a dual purpose. First, as the fiber bundles 10 travel around the rods 20, 22 and 24, they will initially separate and spread out into thinner layers of individual fibers. Second, the redirection rod 18, in conjunction with subsequent processing steps described below, can apply a pulling force to the fiber bundle 10 to limit the movement of the fiber bundle in the general process direction indicated by arrow 26. This tension tensions the fibers downstream of the diverter rod 18, thereby eliminating any undulations in the fibers so that the fibers are aligned in substantially parallel straight lines as they pass through the resin bath 14. As will be apparent from the description below, applying too much tension to the fibers will result in poor quality helical ribbons. By adjusting the horizontal spacing of the rods 20, 22 and 24 in the first rod set 18, the tension applied to the fiber can be adjusted - the closer the rods are to each other, the greater the tension in the fiber, and the farther apart the rods are , the smaller the tension in the fiber.

Coming out of the guide device 12 , the fiber bundles 10 converge on each other while entering the resin bath 14 . Once in the resin bath 14, the tow 10 is pulled through under a set of spreader bars 28, 30 and 32 arranged in a ladder-like arrangement below the surface of the resin 16. That is, the part that pulls through the top two rows of feed holes 13 such as fiber bundle 10 will be pulled from below the spreading rod 28; Pull through below the opening rod 30; As fiber bundles 10 are pulled under spreading bars 28, 30, and 32, respectively, they undergo a significant change in direction of travel and spread further apart from each other, allowing resin 16 to more easily settle between the individual fibers. And soak the fiber bundle. Furthermore, the spreading rods 28, 30 and 32 ensure that the fibers pass through the resin 16 rather than just floating over its surface.

After the resin-coated fibers pass under spreading rods 28, 30, and 32, respectively, they will take the form of composite webbings 34, 36, and 38, each of which contains a plurality of fibers that are oriented substantially in the same direction relative to each other. Continuous fibers extending within a resin matrix. Composite tapes 34, 36 and 38 are pulled through a rubber scraper mechanism 40 as they are pulled from the resin bath 14. Free floating heavier upper rod 44, when the composite webbing 34, 36 and 38 passes the gap 46 between rods 42 and 44, the scraping action of the heavier rod 44 causes the resin between the individual 26 is stressed to increase the extent to which the resin saturates the fiber bundle. Excess resin is scraped off the composite webbing and the composite webbings are combined into a single composite webbing 48 . The composite webbing 48 can be drawn through a carding device 50 comprising an elongated rod extending substantially perpendicular to the direction of travel of the belt 48 and a plurality of fingers 52 extending upwardly across the width of the belt. By drawing a substantially equal number of continuous fibers between every two fingers 52 , the carding device 50 ensures that the fibers are distributed substantially evenly along the entire width of the composite webbing 48 .

After leaving the carding device 50, the webbing 48 is contacted and bonded to a reel 58 sent in the direction of arrow 56 and continuously around rollers 60, 62 and 64 rotating in the directions of arrows 66, 68 and 70. On a continuous belt 54 made of an adhesive barrier material. Composite sling 48 is in contact with the adhesive tape 54 while passing under a scraper 72 made of rubber or another soft material. The scraper 72 scrapes any excess resin 16 off the composite webbing 48 which is then returned to the bath 14 . Once the composite webbing 48 has passed the screed 72, its resin to fiber ratio will remain substantially constant. Desirably, the composite webbing 48 comprises between about 50% and about 90% by weight fibers and between about 10% and about 50% by weight resin; more preferably between about 65% and about 75% by weight fibers and between about 25% and about 35% by weight resin; preferably about 70% by weight fiber and about 30% by weight resin.

Leaving the scraper 72, the adhesive tape 54 and the composite flat tape 48 will travel together as another lamination tape 74, and then the lamination tape will be wound round and round on the mandrel 76 rotating in the direction of the arrow 78, An assembly 80 of alternating layers of composite webbing 48 and barrier tape 54 wound in a helical configuration is formed to ensure that laminate tape 74 is wound tightly around mandrel 76 . A layer of barrier tape 54 or a similar barrier coating may be applied to the mandrel 76 prior to the winding step to allow the assembly 80 to be removed from the mandrel after the resin has set. Since the inner diameter of the assembly 80 corresponds to the outer diameter of the mandrel 76, the particular choice of the diameter dimension of the mandrel 76 will depend on the minimum inner diameter of the helical ribbon required for a particular application. Typically, the diameter of the mandrel 76 is taken to be half the diameter of the structure on which the helical ribbon will ultimately be wound. Desirably, the lamination tape 76 is wound on the mandrel 76 between a pair of spaced apart flanges 84 and 86 so as to define the width of the assembly 80 .

Once the desired number of turns of laminated tape 74 have been wound on mandrel 76 (typically between 10 and 20 turns), assembly 80 on mandrel 76 is cut by cutting the laminated tape perpendicular to its length. from the rest of the lamination tape 74. The mandrel with assembly 80 is then stored under ambient conditions during which time the resin within composite webbing 48 will partially cure or gel to a solid state, securing the many turns within assembly 80 into a helical configuration. The length of this gel time depends on the amount of catalyst added to the resin matrix components. Once gelled, the resin can be fully cured by heating assembly 80 to a temperature between about 100°F and about 250°F, such as in a forced air oven. For the preferred isophthalic polyester resins discussed above, a typical heating program may include a step-by-step cycle in which assembly 80 is first heated to a temperature between about 170°F and about 180°F. hours, then about two hours at about 250°F.

When the resin 16 in the assembly 80 has gelled to a sufficiently hard solid state so that the composite will not undergo permanent deformation, the assembly can be removed from the mandrel 76 and the ends with the resin flash areas can be trimmed. margin so that the component has the desired width. The trimmed edges of assembly 80 are then coated with resin 16 and assembly 80 is processed through a final curing cycle. Once the resin in the assembly is fully cured, the barrier tape 54 can be peeled off leaving a helical band 90 of multiple turns of composite material, as shown in FIG. 3 .

During the step of winding the lamination tape 74 on the mandrel 76, fiber tension along the length of the lamination tape 74 will typically cause the lamination tape to be wound so tightly that each turn of the lamination on the mandrel The belts are all compressed by subsequent turns. Since the resin 16 within the laminated tape 74 is in a fluid state during this winding process, this squeezing action generally tends to distort the surface of the composite webbing 48. In other words, referring to FIG. 5, due to the tension in the fibers, the fibers have a tendency to wrap tightly around the mandrel 76 so that when the barrier tape 54a is made of a material that is not rigid enough, the fibers within the loops 88 of the assembly 80 A localized force will be applied which tends to deform this barrier strip 54a within the previous turn 87 of the assembly. Since the resin in the composite flat strip 48a of this circle 87 is still in an uncured state at this time, the resin will not be able to support the adhesive barrier tape 54a and prevent its local deformation. Instead, the resin will yield to these forces, creating surface undulations or waves extending the length of the loop 87 of composite webbing 48a. As the lamination tape 74 continues to be wound onto the mandrel 76, each subsequent turn of the lamination tape will deform the preceding turns in a similar manner. These surface undulations are indicated by "peaks" 92 and "valleys" 94 in the cross-sectional view of the two-turn spiral ribbon shown in Figures 1a and 1b.

Deformation of the composite webbing 48 that would result in surface corrugations can be substantially eliminated by selection of an appropriate barrier tape 54 . That is, by selecting a barrier tape 54 that is sufficiently rigid not to deform locally during the winding step, a composite webbing can be formed whose surface is a substantially flat assembly 80 as shown in cross-section in FIG. 2 48 circles. At the same time, the barrier tape 54 must be sufficiently flexible so that it can be wound evenly around the mandrel 76 in smoothly curved turns during the winding step. From this point of view, suitable adhesive barrier tapes can be made of materials such as polyester, polypropylene, nylon, etc. After the composite flat tape 48 is cured, these materials will not be firmly bonded to it. stage, they can withstand the heat generated by the resin 16, but also can withstand the heat applied to the assembly 80 during the final curing process. Of course, the rigidity of an adhesive tape depends both on its composition and on its thickness. For example, when polyester film is used as the tape material, the tape preferably has a thickness of between about 0.005 inches and about 0.010 inches. Furthermore, it is preferred that the adhesive tape has at least one substantially flat surface. As used herein, the term "substantially flat" means that the surface of the barrier tape 54 and the surface of the turns of the helical tape 90 should not vary from surface flatness by more than about 1/64 inch per foot in cross-section. The highly desirable flat surface of the barrier tape may also have a textured surface finish.

During the process of the present invention, the surface of the composite webbing 42 will generally match the flatness and surface texture of the surface of the contacting adhesive barrier tape 54 . Accordingly, it is desirable to arrange the step of winding laminated tape 74 onto mandrel 76 so that both surfaces of composite webbing 48 are in contact with the rough-grained but substantially flat surface of the barrier tape. This can be accomplished by sandwiching the composite webbing 48 between the coarse-grained but substantially flat surfaces of the two barrier tapes 54 and 55 during the winding step, as shown in FIG. 6 . But it is better to use only a single adhesive tape with a rough texture on both sides but basically flat. In such a manner, as the laminated tape 74 is applied to the mandrel 76, one surface of the composite webbing 48 will conform to the corresponding surface of the barrier tape 54 in the laminated tape 74, while the other surface of the composite webbing 48 will The surface will conform to the other surface of the barrier tape 54 .

Following essentially the method described above, a helical ribbon 90 is formed having a plurality of concentric coils of high tensile strength composite material. Referring to Figure 3, the spiral ribbon 90 includes an innermost coil having an inner end 96, an outermost coil having an outer end 98, and a plurality of intermediate coils. Such composite tapes desirably comprise a continuous form of a cured resin matrix encapsulating a plurality of continuous fibers of high tensile strength co-oriented in a helical direction. Although co-directional fibers are generally represented by longitudinal parallel lines 100 in FIG. 3, the spaces between every two adjacent parallel lines 100 actually represent hundreds or even thousands of longitudinal fibers. The turns of the helical band 90 have an elastic memory, which means that a force can be used to uncoil the band, but once the force is removed, the band returns to its original helical shape. The elasticity of the loop is preferably such that the force of the band tending to coil into a helix is greater than its weight so that when the band is suspended by the outer end 98, the band will remain in the helical state. Obviously, the surface of the belt will have no undulations, rather at least one surface of the belt will be substantially flat. Preferably, as shown in Figure 2, both surfaces of the belt are substantially flat. It is highly desirable that the flatness of the tape does not vary by more than 1/64 inch per foot in cross-section and that the surface waviness (ie, surface undulation) does not exceed 0.003 inch. Also, the highly desirable tape surface has a nominal surface texture of about 12.5 microinches when measured with a profilometer.

The helical ribbons produced by the process described above can be used to strengthen axially extending structures against damage caused by internal forces. Such structures may include, for example, pipes used to convey fluids under pressure, storage tanks, high-pressure storage vessels, reinforced concrete bridge supports, and other axially-extending structures that can be evaluated with internal forces radially from the inside to the outside structure. In applications where the structure is subject to significant internal pressure, such as gas delivery piping, one or more helical bands 90 may be wrapped around the structure such that the turns of the band are arranged concentrically. Referring to FIGS. 7 and 8 , this reinforcement technique includes the initial step of securing a layer of adhesive pad 102 to the exterior surface of structure 104 . One suitable such adhesive pad 102 may be, for example, a rectangular pad with closed cell vinyl pads of contact adhesive on both sides. As a preferred method, a suitable adhesive 106 may be applied to the outer peripheral surface of the structure 104 prior to winding the helical ribbon 90. Initially, the helical ribbon 90 is bonded to the structure 104 by bonding the outer end 98 to the bonding pad 102 so that the helical ribbon 90 is oriented substantially perpendicular to the axial direction of the structure. With the outer end 98 held in place, the helical ribbon 90 can be wound by winding it around the structure 104 while unwinding the helical ribbon. After the first turn has been wound onto the structure 104, the outer surface of the turn is coated with adhesive 106 and the helical ribbon 90 is wound around the structure to form the next turn. The outer surface of the next turn is then coated with adhesive 106 and turned around again, as shown in FIG. Taping 110 wherein the inner end 96 of strap 90 is in contact with the bottomed turn of tape 110 . The tape 110 preferably includes at least 5 turns of the helical belt 90, most preferably about 8 turns.

Adhesives suitable for use with wrapping helical tape 90 are disclosed in US Patent Application No. 07/942,731 entitled "Method of Repairing Pipeline". The contents disclosed in this reference are hereby incorporated by reference. In short, these adhesives have an initial fluid state, in this state, they have the appropriate viscosity for easy application and bonding, and after the winding is completed, they can cure to a harder and stronger state of bonding. Preferably, these adhesives are resistant to damage from prolonged environmental exposure in the cured state. In this regard, a particularly desirable binder comprises a methyl methacrylate base and a peroxide catalyst for curing the base, the components mixed in appropriate proportions to provide a binder with sufficient curing properties. Time does not complete the binder wrapping process.

As the turns of the helical ribbon 90 are wound onto the structure 104, the elasticity of the composite material causes the turns to hug together with some tightness and hug the outer surface of the structure. It is desirable that once the entire helical ribbon 90 is wound, the edges of the turns are tapped with a piece of wood or the like to align them radially until the edges on each side of the tape 110 are substantially aligned with each other. This alignment is readily accomplished because the turns of the helical ribbon 90 do not have surface relief that snaps together to limit their lateral movement. The turns of the tape 110 may then be further tightened mechanically until the innermost turn of the tape is in intimate contact with the outer surface of the structure 104 . During the tightening process, the uncured adhesive layer 106 between the adjacent rings plays a lubricating role to facilitate the tightening of the rings. As the turns of the tape 110 are tightened, excess adhesive is squeezed out between the turns as the turns come closer together. Since the surface of the spiral band 90 is substantially flat, the opposing surfaces of adjacent figures can be held against each other so that only a thin layer of adhesive 106 is located between these surfaces. As a result, a strong bond will be created to hold adjacent turns of the tape 110 firmly together. Also, the textured surface of the spiral belt 90 will enhance the bond of the adhesive to the turns of the belt. There is no need to coat the last turn of the reel 110 with adhesive 106 . One or more strips, such as fiber tape, may be wrapped around the disk 110 and held tightly in place until the adhesive 106 between the turns has cured to a sufficiently bonded state.

In some applications, it may be desirable to reinforce an axial segment of a structure whose length is greater than the width of a single helical band 90 . In this case, as shown in FIG. 9, several threaded bands 90 may be wrapped around the structure to form a plurality of coils 112, 114, 116, 118 and 120 covering a corresponding axial length of the structure. Each reel 112-120 is formed like reel 110. Although the ribbons 112-120 are shown all abutting each other edge-to-edge, actual contact of one ribbon with the next is not required. Instead, the structure can be adequately strengthened by wrapping individual coils 112-120 with a small gap therebetween.

In those applications where the pressure in the structure is much lower than the pressure in the gas delivery pipeline, reinforcement is not very necessary, as is the case, for example, with the reinforcement of the pillars of bridges made of reinforced concrete. To reinforce the structure, as shown in Figure 10, one or more helical bands 90 may be wrapped around the structure in opposite helical directions of lift. Using the techniques described above for reinforcing structure 104, an adhesive pad (not shown) similar to adhesive pad 102 is used to initially bond outer end 98 of spiral band 90 to structure 122 at an oblique angle. After a layer of adhesive, such as adhesive 106, has been applied to the exterior surface of structure 122, a helical tape 90 can be wound around the structure in a lift helix while unwinding, the helical tape 90 Each revolution of 20 is edged to the previous revolution to form the first lift helical belt 124. If desired, after the entire helical ribbon 90 has been wound onto the structure 122, a second helical ribbon 90 can be wound around it in the same manner. Thus, after a second adhesive pad has been secured to the spiral wrap 124 and a layer of adhesive has been applied thereto, a second spiral wrap 90 can be wound to cover the first spiral wrap 124 . Typically, the second helical ribbon 90 can be wound into a helical ribbon 126 whose turns are opposite to those of the helical ribbon 124, and additional helical ribbons can be wound to form more coils if desired. with layers. Still in that way, the flat surface of the helical belt 90 enables the belt to wrap so flatly on the structure 122 that there is only A thin layer of adhesive. By limiting the adhesive to only a thin layer, a strong bond is formed between the composite parts.

Although the invention has been described with reference to the embodiments, it should be understood that these embodiments are only illustrative of the principles and applications of the invention. It is therefore to be understood that various changes may be made in the disclosed embodiments and that other structural arrangements may be devised without departing from the spirit and scope of the invention as defined by the appended claims. Furthermore, it should be understood that the invention is intended to include various combinations of features described herein in addition to those features specifically indicated in the claims.

Industrial applicability:

The process of the present invention provides composite reinforcing tapes of high tensile strength which can be used more effectively than known reinforcing tapes to repair corroded sections of pipes and to reinforce pipes to limit the propagation of plastic and brittle failures along the pipe .

Claims (31)

1. a manufacturing has the method for the hurricane band of multi-turn high tensile composite material, it is characterized in that comprising the following steps: to provide a kind of resin that a uncured fluid state and solidifies solid state that has; Be provided as the fiber of the continuous high tensile of the multi beam of bundle form, each described fiber tuft comprises many separate single fibers; Launch part at interval so that described fiber tuft is launched into described single fiber at described a plurality of fiber tufts by one group; Along a direction of feed described each single fiber feeding is bathed by a described resin storage tank that is in described uncured fluid state, thereby make described fiber form the continuous bandlet that a described composite material with first and second surfaces is formed by described resin-coating fully; The described bandlet of described composite material is sticked the semirigid adhesive band with at least one planar surface of one deck, and what make at least one surface and described adhesive band in described first and second surfaces of described bandlet is described to being that a planar surface closely contacts to form a stacking band; Described stacking band is wound on the axle, makes on axle, to form a plurality of described composite materials that laminate circle; It is solid-state multi-turn is shaped as a spiral structure that described resin in the described bandlet of described composite material is cured to described curing at least in part; The described bandlet of described adhesive band from described composite material peeled, thereby at least one the described surface in described first and second surfaces of the described bandlet of described composite material is one to be flat surface substantially on the cross section.

2. as the described method of claim l, it is characterized in that, described adhesive band has enough rigidity, so that the described planar surface of at least one of described adhesive band can not be out of shape because of the effect of the described fiber in the described bandlet that is subjected to described composite material in described coiling and curing schedule, but it is again soft enough, so that it can surround on the described axle with smooth song in described coiling step equably.

3. the method for claim 1 is characterized in that, the thickness of described adhesive band is about 0.005 inch.

4. method as claimed in claim 3 is characterized in that, described gluing every band made by nylon.

5. method as claimed in claim 3 is characterized in that described adhesive band is made by polyester resin.

6. as claim 1 or 3 described methods, it is characterized in that there is a nominal surface finishment that is about 12.5 microinch at least one described surface on described first and second surfaces of the described bandlet of described composite material.

7. the method for claim 1, it is characterized in that, described adhesive band has two planar surfaces at least, like this, each described first and second surfaces of described a plurality of described bandlets that laminate the described composite material in the circle all with the described break even chart face of described adhesive band in one contact.

8. method as claimed in claim 7, it is characterized in that, described adhesive band comprises two adhesive bands, each adhesive band has at least one planar surface, described stickup step comprises such step, promptly, with one in described first and second surfaces of the described bandlet of described composite material with described two adhesive bands in one described planar surface closely contact, and in described first and second surfaces of described bandlet of described composite material another closely contacted with another described planar surface in described two adhesive bands, to form described stacking band.

9. the method for claim 1 is characterized in that, described tree refers to that solid-state in described curing is flexible.

10. method as claimed in claim 9 is characterized in that, described resin is chosen from the thing group that comprises polyester resin, vinyl ester resin, polyurethane resin and epoxy resin.

11. method as claimed in claim 10 is characterized in that, described resin comprises a benzene two polyester resins.

12., it is characterized in that described high tensile strength fiber comprises non-metallic fiber as claim 1 or 10 described methods.

13. method as claimed in claim 12 is characterized in that, described high tensile strength fiber is non-conductive.

14. method as claimed in claim 12 is characterized in that, described fiber comprises glass fibre.

15. method as claimed in claim 14 is characterized in that, described glass fibre comprises E type glass fibre.

16., it is characterized in that the diameter of every described fiber is no more than about 0.001 inch as claim 1,3 or 15 described methods.

17., it is characterized in that the described bandlet of described composite material is formed to the described resin between about 50% weight percentage to the described fiber between about 90% weight percentage and about 10% by about 50% as claim 1,9 or 10 described methods.

18. method as claimed in claim 17 is characterized in that, the described bandlet of described composite material is formed to the described resin between about 35% weight percentage to the described fiber between about 75% weight percentage and about 25% by about 65%.

19. method as claimed in claim 18 is characterized in that, the described bandlet of described composite material is made up of the described fiber of about 70% weight percentage and the described resin of about 30% weight percentage.

20. the method for claim 1, it is characterized in that, described the step of described fiber feeding by described resin bath comprised such step, promptly, make described fiber walk around one and be positioned at the parts of described resin, thereby change the described direction of feed of described fiber.

21. the method for claim 1 is characterized in that, described described fiber feeding is also comprised the step that makes described multifilament tensioning before by the step of described resin bath.

22. method as claimed in claim 21 is characterized in that, described tensioning step comprises such step, that is, make described multiple fibre by one group of isolated parts to limit described fiber moving along described direction of feed.

23. method as claimed in claim 3, it is characterized in that, also comprise such step, promptly, the described bandlet of guiding described composite material makes the basic five equilibrium of described many fibers ground by the interval between described a plurality of teeth by a carding apparatus that comprises the tooth at a plurality of intervals.

24. the method for claim 1, it is characterized in that, described axle comprises a pair of flange that radially extends that separates an intended distance, described stacking band is wound on the described axle between described two flanges, like this, the described bandlet of described composite material has basic and described intended distance equal widths.

25. the method for claim 1 is characterized in that, also comprises such step, that is, the described bandlet of described composite material is heated between about 100 °F to about 250 °F so that described resin solidifies fully.

26. the hurricane band with multi-turn high tensile composite material is characterized in that, this band is made by following steps: a kind of resin that a uncured fluid state and solidifies solid state that has is provided; Be provided as the fiber of the continuous high tensile of the multi beam of bundle form, each described fiber tuft comprises many separate single fibers; Launch part at interval so that described fiber tuft is launched into described single fiber at described a plurality of fiber tufts by one group; Along a direction of feed described each single fiber feeding is bathed by a described resin storage tank that is in described uncured fluid state, thereby make described fiber form the continuous bandlet that a described composite material with first and second surfaces is formed by described resin-coating fully; The described bandlet of described composite material is sticked the semirigid adhesive band with at least one planar surface of one deck, and what make at least one surface and described adhesive band in described first and second surfaces of described bandlet is described to being that a planar surface closely contacts to form a stacking band; Described stacking band is wound on the axle, makes on axle, to form a plurality of described composite materials that laminate circle; It is solid-state multi-turn is shaped as a spiral structure that described resin in the described bandlet of described composite material is cured to described curing at least in part; The described bandlet of described adhesive band from described composite material peeled, thereby at least one the described surface in described first and second surfaces of the described bandlet of described composite material is one to be flat surface substantially on the cross section.

27. hurricane band as claimed in claim 26 is characterized in that, described resin is solid-state in described curing to be flexible.

28. hurricane band as claimed in claim 26 is characterized in that, described high tensile strength fiber comprises glass fibre.

29. hurricane band as claimed in claim 26 is characterized in that, the described bandlet of described composite material is formed to the described resin between about 50% weight percentage to the described fiber between about 90% weight percentage and about 10% by about 50%.

30. the high tensile composite material extends axially structure in reinforcement, to make it to resist a kind of application from the radially outer internal force of described structure aspect, it is characterized in that, one hurricane band with multi-turn high tensile composite material is provided, and it is flat substantially on the cross section that every circle has at least one surface; Described multi-circle spiral flow band is surrounded on the described structure, when holding, between the adjacent turn of described multi-turn, apply a layer binder.

31. the high tensile composite material extends axially structure in reinforcement, to make it to resist a kind of application from the radially outer internal force of described structure aspect, it is characterized in that, provide one to constitute a spiral-shaped composite material tape, it ends at an inner and outer end, and a plurality of elastic rings that are used to hold with the described structure of obvolvent are arranged, each circle has an internal surface and an outer surface of being close to the corresponding surface of adjacent turn, described internal surface of at least one of described each circle or outer surface are flat substantially in the cross section, described composite material comprise many be embedded in resin basic in and be parallel to the cellosilk of the continuous high tensile of the described spiral of Hand of spiral extend through; Described composite material tape is surrounded on the described axially extended structure; Described hold step in, between the adjacent turn of described multi-turn, apply a layer binder.

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