CA2306308C - Composite wood flooring - Google Patents
Composite wood flooring Download PDFInfo
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- CA2306308C CA2306308C CA002306308A CA2306308A CA2306308C CA 2306308 C CA2306308 C CA 2306308C CA 002306308 A CA002306308 A CA 002306308A CA 2306308 A CA2306308 A CA 2306308A CA 2306308 C CA2306308 C CA 2306308C
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Abstract
A fiber reinforced composite wood flooring is designed particularly for use in van-type truck trailers which experience adverse operating conditions due to heavy lift truck traffic on the top side and water spray during rainy periods on the bottom side. The composite wood flooring comprises edge-glued laminated wood which is underlaid with a thin layer of fiber reinforced plastic. The top surface of the composite wood floor is the same as that of a conventional laminated wood floor. The fiber reinforced plastic underlay is composed of glass and/or carbon fibers embedded in a polymeric resin such as epoxy, phenolic, vinyl ester, polypropylene or polyamide resin. The fiber reinforcement is designed to enhance the mechanical properties of the flooring in the longitudinal and transverse directions of the floor. The fiber reinforced plastic improves the fatigue resistance of the composite wood flooring and prevents water leakage into the trailer through the floor boards.
Description
COMPOSITE WOOD FLOORING
Background Of The Invention This invention reiates to an improved laminated wood flooring for van-type truck trailers. Fiber reinforced polymeric composite materials are used in conjunction with edge-glued laminated wood flooring to provide improved mechanical properties, moisture protection, fatigue resistance and light weight:
Conventional wood flooring for over-the-road truck trailers is normally manufactured with hardwoods such as oak, maple, birch, beech, etc. The green lumber used as a starting material in such manufacture is suitably dried in special drying chambers under controlled conditions. The dried lumber is then sawed into strips of rectangular cross-section and defective portions are eliminated by cross cutting the strips. During the cross-cutting process, "hooks" are formed at the ends of the lumber strips. The relatively defect free lumber strips are smeared on their vertical sides or edges with an adhesive such as urea-melamine formaldehyde or polyvinyl acetate. The uncured. edge-glued. lumber strips are then assembled on a conveyor by placing them side to side and behind other strips which were previously assembled. The adhesive is cured by applying heat and edge pressure to large sections of the as-sembled lumber strips thus forming a unitary panel. During the assembly of the lumber strips, "hook joints" are. formed at each end of every strip. These joints are simple mechanical couplings with no significant adhesive bonding. Often times, due to imperfect assembly, a readily visible gap is formed at the hook joints which can be seen from the top and bottom surfaces of the completed laminated wood floor.
The cured. laminated wood is cut to a desired length (up to about 60 feet) and: width (about 6 to 18 inches) to form boards. The boards are then planed.
to- a 323.5489 USQ
desired thickness and shiplaps and crusher beads are machined on its sides. A
shiplap is a rectangular projecting lip running along the length on each side of a floor board.
The crusher bead is a small semi-circular projection running along the length on each side of a board and placed over or below a lip. When the floor boards are assembled in a trailer such. that the side edges of corresponding boards are squeezed together, the shiplaps of adjacent boards overlap to form a seam.- The crusher beads provide spacing between adjacent boards and help in preventing buckling of the boards due to expansion on wetting. A wood putty is applied at the hook joints on the top and bottom surfaces of the boards to fill any resident gaps. Finally, the underside of the floor boards are coated with a polymeric substance termed as "undercoating" to provide moisture protection. The finished floor boards are assembled into a kit of about eight boards for installation in trailers. Normally, a kit consists of two boards with special shiplaps so that they will fit along the road and curb sides of a trailer. The other boards may be identical in design and. they are placed between the road and curb side boards.
All the boards are supported by thin-walled cross-members of I, C or hat sections, each having an upper flange, which span the width of the trailer and are regularly spaced along the length of the trailer: Each floor board is- secured to the cross-members by screws extending- through the thicknesses. of the board and the upper flanges of the cross-members.
Hardwood=based laminated wood flooring is popularly used in truck trailers since it offers many advantages. The surface characteristics of hardwoods such as high wear resistance and slip resistance are: most desirable. The strength and stiffness of the flooring: is-important forefficient and safe transfer of the applied loads to the cross-members of the trailer. The shock resistance of wood is useful to withstand any sudden dropping of-heavy cargo on the floor. Nail holding capability and ability to absorb small amounts of water, oil or grease without significantly affecting.
slip resistance are-yet additional favorable properties=of hardwood flooring.
Although the conventional hardwood.flooring has: many desirable features, it also suffers from certain- disadvantages. For example, water from the roads is known to leak into trailers through- the gaps of the hook joints that exist irr the flooring.. The reasons for the: water IeaksF are- believed to. be tha- capillary. action of the gaps and, the tendency of thea enc! gGain- ofs wood: tor- absorbr. and: store water.
Although the 323.5489 USQ
undercoating is supposed to provide a barrier to the path of water, it may not properly cover larger gaps thus exposing them to moisture. Wetting and drying cycles can -,degrade the undercoating leading to its cracking and peeling away from the wood.
Bending of the floor between two adjacent cross-members due to any applied load on the top of the floor also has a tendency to open the hook joints and enlarge the gaps.
A lift.truck is often used on the trailer floor to load and unload cargo. The dynamic action of a moving lift truck placing heavy cargo on the trailer floor creates severe stress concentration in the flooring and some of the cross-members. A
very large proportion of the weight of the lift truck and that of the cargo is transferred to the flooring through the wheels of the front axle of the lift truck due to the momentary raising of the rear axle when the lift truck is dynamically placing a heavy cargo on the floor. The effect of repeated lift truck operation on the conventional wood floor causes considerable fatigue damage including: delamination of the edge glue- lines;
near the hook joints leading to the "pop-out" of the lumber strips; crack initiation and propagation in wood on the underside of the floor due to longitudinal tensile stresses;
and edge glue line delamination due to shearing, transverse bending and twisting: of- the=
floor. The combination of moisture attack and fatigue damage to the wood floor shortens its life thus necessitating its replacement. In some cases, catastrophic structural failure of the trailer flooring system may occur leading to the unacceptable: injury of working personnel and damage to machinery.
I _ _ To alleviate the above.mentioned problems, a novel -fiber reinforced composite wood flooring was designed, tested and refined to be arr improvement..over .
conventional wood flooring. This new composite wood flooring consists of=conventional laminated wood with an underlay of fiber reinforced plastic (FRP). The top:
surfam of the composite wood flooring is essentially the same as that of the, conventional- wood flooring. Since the FRP is impervious to the passage of water, it- completely seals= the bottom of the wood floor and solves the problem of leaky hook joints: The fiber reinforcement improves the mechanical properties of the flooring; anct therefore- the thickness of the laminated wood can be reduced. Thus, a thinnerandlightercomposite-wood flooring can be produced with equivalent- strength when- comparec: to: a3 thicker conventional wood flooring. Since the reinforcement provides arr excellenta barrier to:, 323.5489 USQ
the "pop-out" of lumber strips, the fatigue resistance of the composite wood flooring can be improved over that of the conventional wood flooring.
Technologists are constantly trying to find ways to improve the mechanical properties, reduce weight and improve moisture resistance of wood flooring. Fouquet, U.S. Patent No. 5,143,418 describes the use of composite plywood panels as flooring in truck trailers. The plywood was composed of veneers of wood with a majority of the veneers oriented with the wood grain along the longitudinal direction while the remaining veneers were oriented with the wood grain along the perpendicular direction. The top and bottom surfaces of the plywood panels were overlaid with resin impregnated cellulose sheets for providing moisture and slip resistance.
Clearly, Fouquet has not considered a floor design involving the FRP to provide higher strength and moisture protection.
Another area of related art is the use of FRP to improve the mechanical properties of structural wood members, such as beams, columns and trusses.
Theakston (Canadian Agricultural Engineering, January 1965, Pages- 17-19) has discussed the use: of giass fibers and epoxy resin to reinforce laminated timber beams and' arches. Triantafillou. and Deskovic (Joumal of Structural Engineering, Vol. 118, Na. 5, May 1992, Pages 1270-1284) have published test results on the reinforcement of structural wood beams by adhesively bonding prestressed carbon fiber based FRP
panels using epoxy adhesive. Thus the concept of reinforcing structural wood members> (especially beams) with FRP__ has been known for over two decades:
Tingley, U.S. Patent No. 5,362;545 describes the use of a resorcinol adhesive. to bond certain-special composite- paneis to glue-laminated wood beams (Glulams). The special composite panels: containing an aramid (Kevlar ) fiber reinforcement are abraded by sanding, prior to7 bonding. The sanding process makes the panel "hair up." due to Kevlar and helps to obtain improved bonding with wood. The Tingley patent teaches the utility of Keviar in FRP panels to improve. the bond strength of the FRP to wood while using a resorcinol adhesive.
The above-referenced patents. and publications have not- addressed the construction and related. benefits of reinforced laminated wood flooring for use in truck trailers; Th& advantages of reinforcing: the bottom side and disadvantages of 323.5489 USQ
reinforcing the. top side of the laminated wood boards are not disclosed in these references. The publications do not discuss the remedies for the problems associated with the conventional wood flooring such as water leakage through the hook joints and fatigue damage due to lift truck traffic on the floor. There is no discussion in the publications regarding the type of reinforcements and resins that are suited for the fabrication of reinforced composite wood flooring. For example, the question of whether fiber reinforcement along the width (transverse) direction of the floor is advantageous is not addressed in these publications. A reinforced composite wood flooring construction such as that provided by the present invention which is suitable for lift truck movement and also for carrying cargo in a trailer has never before been invented.
Methods of manufacturing the reinforced composite wood flooring of the invention have never been considered.
Summacy Of The Invention Unlike the FRP-wood structural beams, the reinforced: composite wood, flooring of ther-present- invention is designed to provide several desirable features. The top side of the floor is simply composed of' planed laminated wood as: in the conventional wood flooring of trailer and.truck beds: This providesi a higti coefficient of friction and slip resistance, thereby facilitating the- safe: movement of man and: machine.
The surface ofiwood can also absorb: small amounts; of'water that may spill over it: Any oil or grease that spillson the wood. surface: can be wiped off and: the left over slick is absorbed by the pores of- wood_ as> irr-a: conventional wood flooring:.
Orrthe: contrary, even an extremely thin coating of` oil orr FRP` carr render ifi dangerously slippery and .
therefore, FRP is not laid on the top sidec- ofithe composite wood ffoor. An FRP is laid on the bottom side of the laminated wood: floor to provide protection to wood from the outside environment: The FRP underlay in the. composite wood flooring eliminates the need for a polymeric undercoating. and: for puttying of- hook joints: that may-be required in a conventional wood flooring: In fact; the- need for hook joints;
themselves can be eliminated, that is, the- lumberstrips: can be joined: at butt ends thereof or by finger or lap and gap joints. However, the use of-hook joints: is: preferred. The- gaps in tha hook joints are completely sealed by the FRP'; thus. preventing:water leakage! inta the trailer through the flooring_ Preferably, tkte*.FRPis:fabricated:wittr glass.fibers andan epoxy resin. Other reinforcements sudr ass carborr fiber and other thermosetting resins; such 323.5489 USQ
as vinyl ester, polyester, phenolic resins and the like, and other thermoplastic resins such as polypropylene and polyamide resins and the like can also be used to fabricate the FRP. The-glass fiber reinforcement provides an economical means of increasing the strength of the flooring in the longitudinal and transverse directions.
The epoxy resin binds the glass fibers together and protects the fibers from adverse environment:
The glass fibers resist the pop-out of the lumber strips during fatigue tests, under simulated lift truck loading. of a composite wood floor installed in a trailer. The transverse reinforcement resists the splitting of the FRP and delamination of edge-glue lines in laminated wood due to shearing, twisting and transverse bending loads on the floor. Thus, our design of the composite wood floor provides improvements in the prevention of moisture leakage through hook joints, maintains the desirable surface characteristics of the wood on the top surface and also provides improvements in fatigue resistance at lowerweight _ The manufacture of the composite wood flooring can be accomplished by means of a suitable process wherein the fiber reinforced plastic is bonded to the surface of laminated wood. The fiber reinforcement is saturated with the-resirr and excess resin is squeezed out by passing the reinforcement between squeeze rollers.
The- resin-wetted reinforcement is placed in contact with the surface of the laminated wood and the resin is cured under heat and pressure. A batch-type or continuous hotpress can be used to apply.heat and pressure. on the resin-wetted reinforcement while it is still in contact with the laminated wood. A batch-type hotpress cary be designed with a stationary hot plateri- on which the resin-wetted.
reinforcements. are;
placed. Laminated wood boards are placed on top of the reinforcements: Air bladdersk _ are stationed above the hot platen to apply pressure on the top surface- of the laminated_ wood. In a continuous hotpress, a series of hot rollers placed directly above a set- of-cold rollers can be used. to apply heat and pressure on the composite material: The resin-wetted reinforcement is laid on laminated wood and then the combination-is passed through the gap between the hot and cold rollers. At one end, the laminated wood is pushed into the roller hotpress while at the other end, the cured.
composite:floor is pulled out of the roller hotpress.
The composite wood floor can also be manufactured, by adapting; the:
pultrusion process which normally involves the pulling of resin-wetted.
reinforcement*
Background Of The Invention This invention reiates to an improved laminated wood flooring for van-type truck trailers. Fiber reinforced polymeric composite materials are used in conjunction with edge-glued laminated wood flooring to provide improved mechanical properties, moisture protection, fatigue resistance and light weight:
Conventional wood flooring for over-the-road truck trailers is normally manufactured with hardwoods such as oak, maple, birch, beech, etc. The green lumber used as a starting material in such manufacture is suitably dried in special drying chambers under controlled conditions. The dried lumber is then sawed into strips of rectangular cross-section and defective portions are eliminated by cross cutting the strips. During the cross-cutting process, "hooks" are formed at the ends of the lumber strips. The relatively defect free lumber strips are smeared on their vertical sides or edges with an adhesive such as urea-melamine formaldehyde or polyvinyl acetate. The uncured. edge-glued. lumber strips are then assembled on a conveyor by placing them side to side and behind other strips which were previously assembled. The adhesive is cured by applying heat and edge pressure to large sections of the as-sembled lumber strips thus forming a unitary panel. During the assembly of the lumber strips, "hook joints" are. formed at each end of every strip. These joints are simple mechanical couplings with no significant adhesive bonding. Often times, due to imperfect assembly, a readily visible gap is formed at the hook joints which can be seen from the top and bottom surfaces of the completed laminated wood floor.
The cured. laminated wood is cut to a desired length (up to about 60 feet) and: width (about 6 to 18 inches) to form boards. The boards are then planed.
to- a 323.5489 USQ
desired thickness and shiplaps and crusher beads are machined on its sides. A
shiplap is a rectangular projecting lip running along the length on each side of a floor board.
The crusher bead is a small semi-circular projection running along the length on each side of a board and placed over or below a lip. When the floor boards are assembled in a trailer such. that the side edges of corresponding boards are squeezed together, the shiplaps of adjacent boards overlap to form a seam.- The crusher beads provide spacing between adjacent boards and help in preventing buckling of the boards due to expansion on wetting. A wood putty is applied at the hook joints on the top and bottom surfaces of the boards to fill any resident gaps. Finally, the underside of the floor boards are coated with a polymeric substance termed as "undercoating" to provide moisture protection. The finished floor boards are assembled into a kit of about eight boards for installation in trailers. Normally, a kit consists of two boards with special shiplaps so that they will fit along the road and curb sides of a trailer. The other boards may be identical in design and. they are placed between the road and curb side boards.
All the boards are supported by thin-walled cross-members of I, C or hat sections, each having an upper flange, which span the width of the trailer and are regularly spaced along the length of the trailer: Each floor board is- secured to the cross-members by screws extending- through the thicknesses. of the board and the upper flanges of the cross-members.
Hardwood=based laminated wood flooring is popularly used in truck trailers since it offers many advantages. The surface characteristics of hardwoods such as high wear resistance and slip resistance are: most desirable. The strength and stiffness of the flooring: is-important forefficient and safe transfer of the applied loads to the cross-members of the trailer. The shock resistance of wood is useful to withstand any sudden dropping of-heavy cargo on the floor. Nail holding capability and ability to absorb small amounts of water, oil or grease without significantly affecting.
slip resistance are-yet additional favorable properties=of hardwood flooring.
Although the conventional hardwood.flooring has: many desirable features, it also suffers from certain- disadvantages. For example, water from the roads is known to leak into trailers through- the gaps of the hook joints that exist irr the flooring.. The reasons for the: water IeaksF are- believed to. be tha- capillary. action of the gaps and, the tendency of thea enc! gGain- ofs wood: tor- absorbr. and: store water.
Although the 323.5489 USQ
undercoating is supposed to provide a barrier to the path of water, it may not properly cover larger gaps thus exposing them to moisture. Wetting and drying cycles can -,degrade the undercoating leading to its cracking and peeling away from the wood.
Bending of the floor between two adjacent cross-members due to any applied load on the top of the floor also has a tendency to open the hook joints and enlarge the gaps.
A lift.truck is often used on the trailer floor to load and unload cargo. The dynamic action of a moving lift truck placing heavy cargo on the trailer floor creates severe stress concentration in the flooring and some of the cross-members. A
very large proportion of the weight of the lift truck and that of the cargo is transferred to the flooring through the wheels of the front axle of the lift truck due to the momentary raising of the rear axle when the lift truck is dynamically placing a heavy cargo on the floor. The effect of repeated lift truck operation on the conventional wood floor causes considerable fatigue damage including: delamination of the edge glue- lines;
near the hook joints leading to the "pop-out" of the lumber strips; crack initiation and propagation in wood on the underside of the floor due to longitudinal tensile stresses;
and edge glue line delamination due to shearing, transverse bending and twisting: of- the=
floor. The combination of moisture attack and fatigue damage to the wood floor shortens its life thus necessitating its replacement. In some cases, catastrophic structural failure of the trailer flooring system may occur leading to the unacceptable: injury of working personnel and damage to machinery.
I _ _ To alleviate the above.mentioned problems, a novel -fiber reinforced composite wood flooring was designed, tested and refined to be arr improvement..over .
conventional wood flooring. This new composite wood flooring consists of=conventional laminated wood with an underlay of fiber reinforced plastic (FRP). The top:
surfam of the composite wood flooring is essentially the same as that of the, conventional- wood flooring. Since the FRP is impervious to the passage of water, it- completely seals= the bottom of the wood floor and solves the problem of leaky hook joints: The fiber reinforcement improves the mechanical properties of the flooring; anct therefore- the thickness of the laminated wood can be reduced. Thus, a thinnerandlightercomposite-wood flooring can be produced with equivalent- strength when- comparec: to: a3 thicker conventional wood flooring. Since the reinforcement provides arr excellenta barrier to:, 323.5489 USQ
the "pop-out" of lumber strips, the fatigue resistance of the composite wood flooring can be improved over that of the conventional wood flooring.
Technologists are constantly trying to find ways to improve the mechanical properties, reduce weight and improve moisture resistance of wood flooring. Fouquet, U.S. Patent No. 5,143,418 describes the use of composite plywood panels as flooring in truck trailers. The plywood was composed of veneers of wood with a majority of the veneers oriented with the wood grain along the longitudinal direction while the remaining veneers were oriented with the wood grain along the perpendicular direction. The top and bottom surfaces of the plywood panels were overlaid with resin impregnated cellulose sheets for providing moisture and slip resistance.
Clearly, Fouquet has not considered a floor design involving the FRP to provide higher strength and moisture protection.
Another area of related art is the use of FRP to improve the mechanical properties of structural wood members, such as beams, columns and trusses.
Theakston (Canadian Agricultural Engineering, January 1965, Pages- 17-19) has discussed the use: of giass fibers and epoxy resin to reinforce laminated timber beams and' arches. Triantafillou. and Deskovic (Joumal of Structural Engineering, Vol. 118, Na. 5, May 1992, Pages 1270-1284) have published test results on the reinforcement of structural wood beams by adhesively bonding prestressed carbon fiber based FRP
panels using epoxy adhesive. Thus the concept of reinforcing structural wood members> (especially beams) with FRP__ has been known for over two decades:
Tingley, U.S. Patent No. 5,362;545 describes the use of a resorcinol adhesive. to bond certain-special composite- paneis to glue-laminated wood beams (Glulams). The special composite panels: containing an aramid (Kevlar ) fiber reinforcement are abraded by sanding, prior to7 bonding. The sanding process makes the panel "hair up." due to Kevlar and helps to obtain improved bonding with wood. The Tingley patent teaches the utility of Keviar in FRP panels to improve. the bond strength of the FRP to wood while using a resorcinol adhesive.
The above-referenced patents. and publications have not- addressed the construction and related. benefits of reinforced laminated wood flooring for use in truck trailers; Th& advantages of reinforcing: the bottom side and disadvantages of 323.5489 USQ
reinforcing the. top side of the laminated wood boards are not disclosed in these references. The publications do not discuss the remedies for the problems associated with the conventional wood flooring such as water leakage through the hook joints and fatigue damage due to lift truck traffic on the floor. There is no discussion in the publications regarding the type of reinforcements and resins that are suited for the fabrication of reinforced composite wood flooring. For example, the question of whether fiber reinforcement along the width (transverse) direction of the floor is advantageous is not addressed in these publications. A reinforced composite wood flooring construction such as that provided by the present invention which is suitable for lift truck movement and also for carrying cargo in a trailer has never before been invented.
Methods of manufacturing the reinforced composite wood flooring of the invention have never been considered.
Summacy Of The Invention Unlike the FRP-wood structural beams, the reinforced: composite wood, flooring of ther-present- invention is designed to provide several desirable features. The top side of the floor is simply composed of' planed laminated wood as: in the conventional wood flooring of trailer and.truck beds: This providesi a higti coefficient of friction and slip resistance, thereby facilitating the- safe: movement of man and: machine.
The surface ofiwood can also absorb: small amounts; of'water that may spill over it: Any oil or grease that spillson the wood. surface: can be wiped off and: the left over slick is absorbed by the pores of- wood_ as> irr-a: conventional wood flooring:.
Orrthe: contrary, even an extremely thin coating of` oil orr FRP` carr render ifi dangerously slippery and .
therefore, FRP is not laid on the top sidec- ofithe composite wood ffoor. An FRP is laid on the bottom side of the laminated wood: floor to provide protection to wood from the outside environment: The FRP underlay in the. composite wood flooring eliminates the need for a polymeric undercoating. and: for puttying of- hook joints: that may-be required in a conventional wood flooring: In fact; the- need for hook joints;
themselves can be eliminated, that is, the- lumberstrips: can be joined: at butt ends thereof or by finger or lap and gap joints. However, the use of-hook joints: is: preferred. The- gaps in tha hook joints are completely sealed by the FRP'; thus. preventing:water leakage! inta the trailer through the flooring_ Preferably, tkte*.FRPis:fabricated:wittr glass.fibers andan epoxy resin. Other reinforcements sudr ass carborr fiber and other thermosetting resins; such 323.5489 USQ
as vinyl ester, polyester, phenolic resins and the like, and other thermoplastic resins such as polypropylene and polyamide resins and the like can also be used to fabricate the FRP. The-glass fiber reinforcement provides an economical means of increasing the strength of the flooring in the longitudinal and transverse directions.
The epoxy resin binds the glass fibers together and protects the fibers from adverse environment:
The glass fibers resist the pop-out of the lumber strips during fatigue tests, under simulated lift truck loading. of a composite wood floor installed in a trailer. The transverse reinforcement resists the splitting of the FRP and delamination of edge-glue lines in laminated wood due to shearing, twisting and transverse bending loads on the floor. Thus, our design of the composite wood floor provides improvements in the prevention of moisture leakage through hook joints, maintains the desirable surface characteristics of the wood on the top surface and also provides improvements in fatigue resistance at lowerweight _ The manufacture of the composite wood flooring can be accomplished by means of a suitable process wherein the fiber reinforced plastic is bonded to the surface of laminated wood. The fiber reinforcement is saturated with the-resirr and excess resin is squeezed out by passing the reinforcement between squeeze rollers.
The- resin-wetted reinforcement is placed in contact with the surface of the laminated wood and the resin is cured under heat and pressure. A batch-type or continuous hotpress can be used to apply.heat and pressure. on the resin-wetted reinforcement while it is still in contact with the laminated wood. A batch-type hotpress cary be designed with a stationary hot plateri- on which the resin-wetted.
reinforcements. are;
placed. Laminated wood boards are placed on top of the reinforcements: Air bladdersk _ are stationed above the hot platen to apply pressure on the top surface- of the laminated_ wood. In a continuous hotpress, a series of hot rollers placed directly above a set- of-cold rollers can be used. to apply heat and pressure on the composite material: The resin-wetted reinforcement is laid on laminated wood and then the combination-is passed through the gap between the hot and cold rollers. At one end, the laminated wood is pushed into the roller hotpress while at the other end, the cured.
composite:floor is pulled out of the roller hotpress.
The composite wood floor can also be manufactured, by adapting; the:
pultrusion process which normally involves the pulling of resin-wetted.
reinforcement*
323.5489 USQ
through a stationary heated die where the FRP is shaped and the resin is cured. The laminated wood and the resin-wetted reinforcement can be pulled together through a heated die to produce composite wood flooring. Altematively; a suitable prefabricated FRP sheet can be bonded to laminated wood using thennosetting or thermoplastic adhesives. The. FRP sheet can be produced by pultrusion and continuous lamination processes. In the pultrusion process, the resin wetted reinforcements are pulled through a stationary, heated die where the FRP is shaped and cured. In continuous lamination process, reinforcements are wetted with a polymeric resin. The wetted reinforcements are aligned in a die and then cured in an oven. Typical reinforcements used for the pultrusion process include continuous rovings, stitched, woven or knitted fabrics and continuous strand mats. In the continuous lamination process, chopped strands and chopped strand mats can be used in addition to the above-mentioned reinforcements. Preferred reinforcements for our prefabricated FRP are continuous rovings in the longitudinal direction of the FRP sheet and fabrics for transverse reinforcement. The fabrics may also be designed to provide bidirectional structural properties:
The present invention provides a novel composite wood flooring for use in truck trailers: that is: subjected. to lift truck traffic on the top side and water spray on the bottom side: Tha composite wood-flooring_ consists of conventional laminated_ wood to which a fiber reinforced plastic polymer is adhesively bonded on the bottom side. Since the topL side is. compoped of wood, many desirable features of wood such as slip resistance; abrasiorr resistance and na+ling. capability are preserved. The underlayerof the composita wood: flooring provides improved fatigue strength and moisture protection to wood. Since-the mechanical properties ofthe reinforced composite wood flooring are superior to those of the conventional wood flooring, the thickness of the composite wood floor can be reduced leading to lower floor weight in a trailer.
Altematively, the load: canying capacity of' the trailer can be increased with a suitable composite floor while havinglittle,. orno increase in the:weightofthe trailer.
Brief" Qescriptiorr Of The Drawings Fg=r 1' ist m perspective view of a van trailer showing. the composite wood_ fCooring installed:orr cross=memberswith arr I-section.
through a stationary heated die where the FRP is shaped and the resin is cured. The laminated wood and the resin-wetted reinforcement can be pulled together through a heated die to produce composite wood flooring. Altematively; a suitable prefabricated FRP sheet can be bonded to laminated wood using thennosetting or thermoplastic adhesives. The. FRP sheet can be produced by pultrusion and continuous lamination processes. In the pultrusion process, the resin wetted reinforcements are pulled through a stationary, heated die where the FRP is shaped and cured. In continuous lamination process, reinforcements are wetted with a polymeric resin. The wetted reinforcements are aligned in a die and then cured in an oven. Typical reinforcements used for the pultrusion process include continuous rovings, stitched, woven or knitted fabrics and continuous strand mats. In the continuous lamination process, chopped strands and chopped strand mats can be used in addition to the above-mentioned reinforcements. Preferred reinforcements for our prefabricated FRP are continuous rovings in the longitudinal direction of the FRP sheet and fabrics for transverse reinforcement. The fabrics may also be designed to provide bidirectional structural properties:
The present invention provides a novel composite wood flooring for use in truck trailers: that is: subjected. to lift truck traffic on the top side and water spray on the bottom side: Tha composite wood-flooring_ consists of conventional laminated_ wood to which a fiber reinforced plastic polymer is adhesively bonded on the bottom side. Since the topL side is. compoped of wood, many desirable features of wood such as slip resistance; abrasiorr resistance and na+ling. capability are preserved. The underlayerof the composita wood: flooring provides improved fatigue strength and moisture protection to wood. Since-the mechanical properties ofthe reinforced composite wood flooring are superior to those of the conventional wood flooring, the thickness of the composite wood floor can be reduced leading to lower floor weight in a trailer.
Altematively, the load: canying capacity of' the trailer can be increased with a suitable composite floor while havinglittle,. orno increase in the:weightofthe trailer.
Brief" Qescriptiorr Of The Drawings Fg=r 1' ist m perspective view of a van trailer showing. the composite wood_ fCooring installed:orr cross=memberswith arr I-section.
323.5489 USQ
Fig. 2 is a longitudinal sectional view of a composite wood floor board fastened to cross-members of the I-section.
Fig. 3 is the end view of the shiplap assembly of two adjacent composite wood floor boards.
Fig. 4a is a perspective view of laminated wood with several randomly arranged hook joints.
Fig. 4b is a perspective view of two opposing hooked ends of lumber strips.
Fig. 4c is a perspective view of a perfect hook joint with little or no gap.
Fig. 4d is a perspective view of an imperfect hook joint. with a significant 9ap-Fig. 5 is a perspective view of a conventional laminated wood: floor board.
Fig. 6 is a perspective view of a reinforced- composite wood floor board- of a first embodiment of the invention.
I _ _ Fig. T is a sectional view of a reinforced composite wood floor board: of a second embodiment- of-the: invention.
Fig. 8 is a perspective view of a reinforced composita wood floor board of a third embodiment of the invention.
Fig. 9 is a sectional view showing a typical Iayup offiber~reinforcements:
Fig. 2 is a longitudinal sectional view of a composite wood floor board fastened to cross-members of the I-section.
Fig. 3 is the end view of the shiplap assembly of two adjacent composite wood floor boards.
Fig. 4a is a perspective view of laminated wood with several randomly arranged hook joints.
Fig. 4b is a perspective view of two opposing hooked ends of lumber strips.
Fig. 4c is a perspective view of a perfect hook joint with little or no gap.
Fig. 4d is a perspective view of an imperfect hook joint. with a significant 9ap-Fig. 5 is a perspective view of a conventional laminated wood: floor board.
Fig. 6 is a perspective view of a reinforced- composite wood floor board- of a first embodiment of the invention.
I _ _ Fig. T is a sectional view of a reinforced composite wood floor board: of a second embodiment- of-the: invention.
Fig. 8 is a perspective view of a reinforced composita wood floor board of a third embodiment of the invention.
Fig. 9 is a sectional view showing a typical Iayup offiber~reinforcements:
-9- .
323.5489 USQ
Detailed Description Of The Preferred Embodiment The reinforced composite wood flooring of the present invention is an improvement over conventional wood flooring of truck trailers in that it provides both moisture proofing and reinforcement to such flooring. In order to understand the benefits provided by the composite wood flooring, it is first necessary to understand the construction of conventional laminated wood flooring.
Conventional wood flooring 11 for over-the-road truck trailers 12 such as that shown in Fig. I is normally manufactured with hardwoods such as ash, aspen, elm, yellow-poplar, and preferably oak, maple, birch, beech and the like, although softwoods such as Douglas fir and spruce could be employed. The green lumber used as a starting material in such manufacture is suitably dried in special drying chambers under controlled conditions. The dried lumber is then sawed into strips 21` of rectangular cross-section and defective portions are eliminated by cross cutting the.
strips. During the cross-cutting process, "hooks" 24 are formed at the ends of the lumber strips (see Fig: 4b). The"reiatively defect-free lumber strips are smeared on theirvertical sides or edges 25 with an adhesive such as urea-melamine formaldehyde or polyvinyl acetate.
The uncured. edge-glued lumber strips are then assembled on a conveyor by placing them side to side and behind other strips which were previously assembled forming glue lines 2Z between adjacent strips 21'. The adhesive is cured by applying heat and edge pressure to large sections- of the assembled-lumber strips thus forming a unitary panel of laminated wood 2Q such as that shown in Fig. 4a. During the-assembly of the lumber strips, "hook joints" 23 are formed at- each end of every strip (see Fig. 4c).
These joints are simple mechanical couplings with no significant adhesive bonding.
Often times, due to imperfect assembly, a readily visible gap 26 is formed at the hook joints which can be seen from the top and bottom surfaces of the completed laminated wood floor (see Fig. 4d).
The cured laminated wood 20 is cut- to a desired length (up to about 60 feet) and width (about 6 to 18 inches) to form a laminated wood. board 16:
(see Fig~ 5).
The_ laminated wood boards 16 are then planed to a desired thickness and.
shiplaps 18:
and crusher beads. 19- are machined on its sides. A shiplap 18: is; a rectangular projecting lip running. along the length on each side of a floor board.. The crusher bead 323.5489 USQ
19 is a small semi-circular projection running along the length on each side of a board and placed over or below a shiplap 18. When the floor boards are assembled in a trailer such that the side edges of corresponding boards are squeezed together, the shiplaps 18 of adjacent boards overlap to form a seam. The crusher beads 19 provide spacing between adjacent boards and help in preventing buckling of the boards due to expansion on wetting. A wood putty is applied at the hook joints 23 on the top and bottom surfaces of the boards to fill any resident gaps. Finally, the underside of the floor boards are coated with a polymeric substance termed as "undercoating" 27 to provide moisture protection. The finished floor boards are assembled into a kit of about eight boards for installation in trailers: Normally, a kit consists of two boards with special shiplaps so that they will fit along the road and curb sides 15 of a trailer 12.
The other boards may be identical in design and they are placed between the road and curb side boards. All the boards are supported by thin-walled cross-members 14 of I, C
or hat sections, each having an upperflange, which span the width of the trailer and are regularly spaced: along the length of the- trailer. Each floor board is secured to the cross-members by screws. 13 extending through the thicknesses of the board and the=
flanges.of the cross-members (See Fgures:1-3).
The reinforced- composite wood- flooring of the present invention improves the above described construction of conventional wood flooring by moisture proofing the flooring and reinforcing the flooring witha laminate layer of fiber reinforced plastic.
(FRP) 17 (as representatively shown in- Figures. 6-8).
Three basic- designs of- the= composite wood floor of the invention with laminated wood board 1S on top and FRP IT on the bottom are presented. below.
These designs differ from one.- another in their physical forms- so that they may be suitable for- manufacture: by appropriate methods. The primary functions of the FRP 17 in all the-designs are:-essentially the-same, i.e., to improve the mechanical and fatigue properties of the floor and also ta provide, a. barrier to the seepage of moisture into the trailer througti the wood-, flooring. In~ addition, the FRP 17 can have other important functions as detailed below: The- firstr second, and third design embodiments.
are shown in- Fig 6; Fig T, and:Fig: 8; respectively.
323.5489 USQ
Detailed Description Of The Preferred Embodiment The reinforced composite wood flooring of the present invention is an improvement over conventional wood flooring of truck trailers in that it provides both moisture proofing and reinforcement to such flooring. In order to understand the benefits provided by the composite wood flooring, it is first necessary to understand the construction of conventional laminated wood flooring.
Conventional wood flooring 11 for over-the-road truck trailers 12 such as that shown in Fig. I is normally manufactured with hardwoods such as ash, aspen, elm, yellow-poplar, and preferably oak, maple, birch, beech and the like, although softwoods such as Douglas fir and spruce could be employed. The green lumber used as a starting material in such manufacture is suitably dried in special drying chambers under controlled conditions. The dried lumber is then sawed into strips 21` of rectangular cross-section and defective portions are eliminated by cross cutting the.
strips. During the cross-cutting process, "hooks" 24 are formed at the ends of the lumber strips (see Fig: 4b). The"reiatively defect-free lumber strips are smeared on theirvertical sides or edges 25 with an adhesive such as urea-melamine formaldehyde or polyvinyl acetate.
The uncured. edge-glued lumber strips are then assembled on a conveyor by placing them side to side and behind other strips which were previously assembled forming glue lines 2Z between adjacent strips 21'. The adhesive is cured by applying heat and edge pressure to large sections- of the assembled-lumber strips thus forming a unitary panel of laminated wood 2Q such as that shown in Fig. 4a. During the-assembly of the lumber strips, "hook joints" 23 are formed at- each end of every strip (see Fig. 4c).
These joints are simple mechanical couplings with no significant adhesive bonding.
Often times, due to imperfect assembly, a readily visible gap 26 is formed at the hook joints which can be seen from the top and bottom surfaces of the completed laminated wood floor (see Fig. 4d).
The cured laminated wood 20 is cut- to a desired length (up to about 60 feet) and width (about 6 to 18 inches) to form a laminated wood. board 16:
(see Fig~ 5).
The_ laminated wood boards 16 are then planed to a desired thickness and.
shiplaps 18:
and crusher beads. 19- are machined on its sides. A shiplap 18: is; a rectangular projecting lip running. along the length on each side of a floor board.. The crusher bead 323.5489 USQ
19 is a small semi-circular projection running along the length on each side of a board and placed over or below a shiplap 18. When the floor boards are assembled in a trailer such that the side edges of corresponding boards are squeezed together, the shiplaps 18 of adjacent boards overlap to form a seam. The crusher beads 19 provide spacing between adjacent boards and help in preventing buckling of the boards due to expansion on wetting. A wood putty is applied at the hook joints 23 on the top and bottom surfaces of the boards to fill any resident gaps. Finally, the underside of the floor boards are coated with a polymeric substance termed as "undercoating" 27 to provide moisture protection. The finished floor boards are assembled into a kit of about eight boards for installation in trailers: Normally, a kit consists of two boards with special shiplaps so that they will fit along the road and curb sides 15 of a trailer 12.
The other boards may be identical in design and they are placed between the road and curb side boards. All the boards are supported by thin-walled cross-members 14 of I, C
or hat sections, each having an upperflange, which span the width of the trailer and are regularly spaced: along the length of the- trailer. Each floor board is secured to the cross-members by screws. 13 extending through the thicknesses of the board and the=
flanges.of the cross-members (See Fgures:1-3).
The reinforced- composite wood- flooring of the present invention improves the above described construction of conventional wood flooring by moisture proofing the flooring and reinforcing the flooring witha laminate layer of fiber reinforced plastic.
(FRP) 17 (as representatively shown in- Figures. 6-8).
Three basic- designs of- the= composite wood floor of the invention with laminated wood board 1S on top and FRP IT on the bottom are presented. below.
These designs differ from one.- another in their physical forms- so that they may be suitable for- manufacture: by appropriate methods. The primary functions of the FRP 17 in all the-designs are:-essentially the-same, i.e., to improve the mechanical and fatigue properties of the floor and also ta provide, a. barrier to the seepage of moisture into the trailer througti the wood-, flooring. In~ addition, the FRP 17 can have other important functions as detailed below: The- firstr second, and third design embodiments.
are shown in- Fig 6; Fig T, and:Fig: 8; respectively.
323.5489 USQ
As shown in Fig. 6, the reinforced composite wood floor board consists of a laminated wood floor board 16 with an underlayer of FRP 17. The shiplaps t8 and ',crusher beads 19 are machined on the sides of the reinforced composite wood floor board similarly to those in a conventional laminated wood floor board (Fig.
5).
The embodiment of Fig:. 7 differs slightly" from that of Fig. 6. The laminated wood floor board 16 with conventional shiplaps 18 is enclosed on the bottom side by a U-shaped FRP 17. The U-shaped FRP 1.7 is formed separately from the wood flooring by a conventional pultrusion process. The bottom comers 28 of the laminated wood board 16 are chamfered. The chamfered edges facilitate the attachment and adhesion of the U-shaped FRP 17 to the bottom and side surfaces of the board.
As shown in Fig. 8, a laminated wood floor board 16' is fully enclosed by an FRP ori three sides including the bottom and the two vertical sides_ A
small' portion of the top surface at the two sides of the board are also covered by, the FRP.
The=
shiplaps are formed by thin-walled box-type ribs 29 of FRP IT which are integrally attached to the FRP underlayer. This embodiment of the FRP 17 layer provides moisture proofing across the bottom, along the opposite sides, and over portions of the.
board top surface.
Process I for Embodiment I(FiQs. 6 and 9) :
Conventional laminated wood 20 is constructed according.: ta the~ method set forth above. The FRP 17 layer is bonded to the sanded bottom, surface= of tha laminated wood 20. A typical layup of the FRP 17 for Process I is; showrr irt Fg 9: The-FRP IT consists of continuous or chopped strand mats 30; fabrics 31; and~ a:=
suitable polymeric resin 32.such as epoxy or phenolic that can provide good:adhesiorr tawood:
A plurality of fabrics 31 are altemated with- a plurality of mats 30 irr the, layupr; and a mat-30 is also used adjacent to the wood surface. A layer of resin 3Z is: applied between each of the altemated layers- of mats_ 30: and fabrics 31, which- soaks;
into:these:layers_ Since the mat adjacent to the wood surface provides a higher resirr content,, it, improves:
the delamination resistance between the FRP 1T and: laminatedr wood: 2M
and:also:
between any two adjacent layers of fabrics. Instead. of the, multiple layers:of: mats. andr 323.5489 USQ
fabrics, a single layer of fabric of the reinforcing fibers can be used to form the FRP.
The fabric can also be designed to have a layer of mat stitched to it, if required. The fiber reinforcement of the FRP 17 contains about 70 to 100%, more preferably about 90 to 100%, of its continuous fibers in the longitudinal direction while the remaining fibers are aligned along the lateral direction of the floor. The longitudinal fibers impart higher mechanical properties along the length direction of the 'floor and offer resistance to "pop-out" of lumber strips 21 near the hook joints 23 under fatigue loading.
The lateral fibers impart higher mechanical properties in the width direction of the floor and offer resistance to the longitudinal splitting of the composite and/or glue lines 22 in the laminated wood 20 while enduring lift truck loads. Altematively, the FRP 17 is designed such that about 7G to 100%, preferably about 90 to 100%, of the strength of the reinforcing fibers alone contribute to the longitudinal strength of the FRP
and floor boards.
The resin wetted reinforcements comprising the FRP layer are stacked on the lower platen of a hotpress and the laminated wood 20 is placed on top of the stack -with its sanded bottom face in contact with the reinforcement layers of the FRP.
Pressure- is applied: by means of air bags on the top surface of the laminated, wood 20 to. compact the wetted. reinforcement beneath the laminated wood 20. Heat is:
applied on the- bottom side of th& FRP layer by the hotpress to cure the resin and bond the reinforcements to the laminated wood 20: The reinforced composite wood. board, comprising the laminated-wood 20, and the FRP 17, is then ripped into several boards 16whictr are: therr machined. on the sides to form the shiplaps 18 and crusher beads 19:
Process. II for Embodiment I(FiQs: 4a and 6):
Conventional laminated wood 20 constructed according to the method set forth above is sanded: on the top side and also planed on the bottom side.
Resin-wetted- reinforcements= of the FRP layer, which includes a combination of continuous rovings; fabrics- and mats; are continuously laid above the sanded surface of the laminatedwood. 20: as: it, is moved over a roller conveyor: A release sheet, is laid over the wet:~ FRP' layer. The laminated wood 21M is pushed into a gap between two sets: of rollers; one~ abov& the: other. The top rollers, are hot and in direct contact-with the release sheet covering the- wet reinforcement FRP layer. The FRP is compacted and 323.5489 USQ
bonded to the laminated wood 20 due to the heat and pressure applied on it by the top rollers. The reinforced composite floor thus formed is continuously pulled out of the roller press at the end of the roller conveyor. It will be understood that the laminated wood 20, as shown in Fig. 4a, is converted to a laminated wood board 16, as shown in Fig. 6, after the FRP 17 layer is applied and after the laminated wood. 20 with FRP 17 is machined conventially to form shiplaps 18- and crusher beads 1% thereon.
Process III for Embodiments I(Fi4. 6) and II (Fia. 7):
A laminated wood floor board 16 with shiplaps 18 and crusher beads 19 are fabricated by the conventional process set forth above. A prefabricated FRP flat sheet is then adhesively bonded. to the. bottom side of the board. to produce a reinforced composite floor board in accordance with Embodiment I. The laminated wood board is sanded on one side to develop a. flatter surface than that provided by planing. The FRP
sheet is also sanded on one side to render it flat and. clean for bonding_ An adhesive is coated on the sanded side of the board and/or the FRP. The edges of the FRP
are-aligned along the edges of the wood board. The- FRP is bonded to wood board using a platen press or rollers that can apply pressure. Heat- is applied. on the: FRP
to cure the adhesive in the case of thermosetting.=adhesives such- as epoxy, polyurethane and phenolic. For thermoplastic adhesives, the combination of the FRP and: wood board is compacted using pressure rollers with cooling. The- FRP' is fabricated with continuous fibers in the form of continuous- rovings- and fabrics. Preferably, mats- are.
not used. in this case. About 70% to about 100%" of` the.fiber reinforcement is aligned along the longitudinal direction while the remainingfibers are aligned along the lateral direction of the FRP/floor board. Altematively, a. pultruded: FRP with a U-shaped cross-section is bonded to the bottom and opposite left and right- sides of- the board to produce a reinforced composite floor in accordance-with Embodiment 11. An adhesive is-applied on the preformed, U-shaped FRP and- the sanded bottorrr surface of the floor board. The bonding of the FRP to the board: is, don& under pressure in a hotpress. or by using compaction rollers. Chamfers are: providedalongthe>lefkand right bottom comers 28 of the floor boards to easetheirassembly inta the': U-shaped:FRP panels: as~
shown in Fig.
7. The space betweerr the- insidw comers of the U-shaped FRPIan& the chamfered bottom comers 28: of the= wood: floor boarcl: help: to; hoid excess; adhesive that may be squeezed-out during the: bondingoperatiorr.CA 02306308 2000-04-20 323.5489 USQ
Process IV for Embodiments I(Fia. 6). II (Fig. 7). and III (Fio. 8):
A laminated wood board 16 is constructed according to the conventional method set forth above. The FRP layer is then fabricated and simultaneously bonded to the board, with or without conventional shiplaps,- by laying the resin-wetted reinforcements, comprising a combination of the strand mats 30, fabrics 31, and continuous rovings on the sanded surface of the laminated wood board 16 and pulling the combination together through a heated die. This process is an adaptation of the pultrusion process which normally involves the pulling of resin-wetted:
reinforcements through a heated die. The FRP is formed in correspondence to the shape of the die while the resin is cured in the die.
A 20 foot long composite wood floor kit~ consisting of eight floor boards was fabricated according to Process I as detailed above. The laminated wood was made of red and white oak strips which were edge-glued using urea-melamine fonnaldehyde"adhesive. About 50 oz/sq yd of E-glass reinforcements were used in the form of woven rovings and continuous strand mats to fabricate the reinforced:
composite - wood floor boards. A resin system consisting of Bisphenol-A epoxy resin, a reactive diluent, flexibilizer and an amine curing agent was used to bind. the reinforcements, and bond them to the laminated wood. The finished thickness of the reinforced composite wood floor was about 1,.19 inches.
In testing the reinforced composite wood floor of the invention; eight reinforced composite wood floor boards were installed in a van trailer after removing, a 20 foot section of its existing wood flooring close to the central part of the trailer. The floor was supported by I-beam cross-members running along the width of the traiierand regulariy spaced at 12 inches in the test section. The cross-members with-asectiorr of 4 inches by 2.25 inches were made of steel with a yield strength of 80 ksi andweighing, about 3.2 Ibs/foot The floor boards were secured. to each cross-member in the-test-section by three screws running through the thicknesses of the- boards: and the_ top flange of the cross-member. A lift truck simulator with two loading wheels;
and: two~
steering wheels was stationed on the floor. The: simulator was: loaded: wittr.
dea&
weights so that a force of about 16,500 lbs could be applied on the-floorthrougfrthe4 323.5489 USQ
loading wheels. The force applied on the floor through the steering wheels was relatively insignificant. To subject the floor to fatigue loading, the simulator was moved back and forth on the floor such that the loading wheels could travel about 13 feet in each direction in the central portion of the composite floor. The simulator was allowed to complete 3,000 fatigue loading cycles, wherein during each cycle the simulator moved by 13 feet in one direction and retumed back to its starting line. At the end of 3,000 fatigue loading cycles, the reinforced composite floor experienced little or no significant damage.
In another test, a 0.125-inch thick, two-inch wide and about 98-inch long steel shim was used between the cross-members and the reinforced composite floor.
As before, the floor system was tested at 16,500 lbs. At the completion of 3,000 fatigue cycles at the load of 16,500 Ibs, the simulatorwas reconfigured so as to apply a force of about 23,000 lbs on the floor: Once again, the simulator was moved back and forth to complete another 3,000-fatigue cycles at the high load. The reinforced composite wood floor was checked: to. determine the level of damage due to the repeated loading or fatigue. There was no significant breakage or fracture of the floor on its underside.
The glass fibers were intact; although wood. seemed to have fractured on the top side of the: floor near some of the shiplaps. The motion of the simulator was unaffected. at all times during the-test: There were no holes or splinters on the bottom side of the floor.
A conveRtional oak floorwith a nominal thickness of 1.38" was tested: in a trailer by repeating the above-mentioned fatigue test procedure. The wood floor was laid. directly: over the: cross-members. On. the completion of 3,000 fatigue cycles at 16;500 Ibs of loading, the. conventional oak floor showed some damage in the form of cracking. of edge=. glue: lines and pop-out of lumber strips near some of the hook joints.
Slight: fracture of lumber strips was- also noticed at a few locations. When the fatigue test- was continued: at ar increased: load of 23,000 lbs., the floor experienced severe damage- everr in the first 200 fatigue cycles. The floor was seen to fracture at several locations:and.produce:asignificantamountof cracking noise. After about 400 cycles at 23,00Q Ibs:, the floor appeared to have little or no strength and stiffness at locations between- some adjacent'cross=members:At this time, the simulator wheels essentially roiled averthe: cross-members; and: dived in and out of the pits created due to the severely. damaged: floor sections This- caused considerable shaking and vibration in 323.5489 USQ
the trailer due to a bumpy path created by broken floor sections. Clearly, the conventional oak floor failed the test and therefore proved to be much inferior to the composite wood flooring.
It was clear from the above-mentioned tests that a 1.19" thick reinforced composite wood flooring weighing about 4.9 lbs/sq ft could be superior to a 1.38" thick conventional wood flooring weighing about 5.4 lbs/sq ft. The reinforced composite floor can be used in trailers to sustain nominal lift truck loads of 16,500 lbs while saving about half pound of weight per square foot of the floor. In addition, with slight modification of the design of the cross-members, the load carrying capacity of the truck floor system can be increased considerably with little or no increase in the weight of the trailer. The excellent fatigue resistance of the reinforced composite flooring is essentially due to the ability of the FRP underlayer to prevent the pop-out of the lumber strips. The hook joints are completely covered on the bottorrr side of the floor and therefore water cannot penetrate through their gaps into the trailer. Due to the higher strength of the reinforced composite wood floor, its thickness can be reduced below that of an equivalent conventional wood floor. This in tum can lead to a significant weight saving in a trailer and hence increase its cargo carrying capacity.
As shown in Fig. 6, the reinforced composite wood floor board consists of a laminated wood floor board 16 with an underlayer of FRP 17. The shiplaps t8 and ',crusher beads 19 are machined on the sides of the reinforced composite wood floor board similarly to those in a conventional laminated wood floor board (Fig.
5).
The embodiment of Fig:. 7 differs slightly" from that of Fig. 6. The laminated wood floor board 16 with conventional shiplaps 18 is enclosed on the bottom side by a U-shaped FRP 17. The U-shaped FRP 1.7 is formed separately from the wood flooring by a conventional pultrusion process. The bottom comers 28 of the laminated wood board 16 are chamfered. The chamfered edges facilitate the attachment and adhesion of the U-shaped FRP 17 to the bottom and side surfaces of the board.
As shown in Fig. 8, a laminated wood floor board 16' is fully enclosed by an FRP ori three sides including the bottom and the two vertical sides_ A
small' portion of the top surface at the two sides of the board are also covered by, the FRP.
The=
shiplaps are formed by thin-walled box-type ribs 29 of FRP IT which are integrally attached to the FRP underlayer. This embodiment of the FRP 17 layer provides moisture proofing across the bottom, along the opposite sides, and over portions of the.
board top surface.
Process I for Embodiment I(FiQs. 6 and 9) :
Conventional laminated wood 20 is constructed according.: ta the~ method set forth above. The FRP 17 layer is bonded to the sanded bottom, surface= of tha laminated wood 20. A typical layup of the FRP 17 for Process I is; showrr irt Fg 9: The-FRP IT consists of continuous or chopped strand mats 30; fabrics 31; and~ a:=
suitable polymeric resin 32.such as epoxy or phenolic that can provide good:adhesiorr tawood:
A plurality of fabrics 31 are altemated with- a plurality of mats 30 irr the, layupr; and a mat-30 is also used adjacent to the wood surface. A layer of resin 3Z is: applied between each of the altemated layers- of mats_ 30: and fabrics 31, which- soaks;
into:these:layers_ Since the mat adjacent to the wood surface provides a higher resirr content,, it, improves:
the delamination resistance between the FRP 1T and: laminatedr wood: 2M
and:also:
between any two adjacent layers of fabrics. Instead. of the, multiple layers:of: mats. andr 323.5489 USQ
fabrics, a single layer of fabric of the reinforcing fibers can be used to form the FRP.
The fabric can also be designed to have a layer of mat stitched to it, if required. The fiber reinforcement of the FRP 17 contains about 70 to 100%, more preferably about 90 to 100%, of its continuous fibers in the longitudinal direction while the remaining fibers are aligned along the lateral direction of the floor. The longitudinal fibers impart higher mechanical properties along the length direction of the 'floor and offer resistance to "pop-out" of lumber strips 21 near the hook joints 23 under fatigue loading.
The lateral fibers impart higher mechanical properties in the width direction of the floor and offer resistance to the longitudinal splitting of the composite and/or glue lines 22 in the laminated wood 20 while enduring lift truck loads. Altematively, the FRP 17 is designed such that about 7G to 100%, preferably about 90 to 100%, of the strength of the reinforcing fibers alone contribute to the longitudinal strength of the FRP
and floor boards.
The resin wetted reinforcements comprising the FRP layer are stacked on the lower platen of a hotpress and the laminated wood 20 is placed on top of the stack -with its sanded bottom face in contact with the reinforcement layers of the FRP.
Pressure- is applied: by means of air bags on the top surface of the laminated, wood 20 to. compact the wetted. reinforcement beneath the laminated wood 20. Heat is:
applied on the- bottom side of th& FRP layer by the hotpress to cure the resin and bond the reinforcements to the laminated wood 20: The reinforced composite wood. board, comprising the laminated-wood 20, and the FRP 17, is then ripped into several boards 16whictr are: therr machined. on the sides to form the shiplaps 18 and crusher beads 19:
Process. II for Embodiment I(FiQs: 4a and 6):
Conventional laminated wood 20 constructed according to the method set forth above is sanded: on the top side and also planed on the bottom side.
Resin-wetted- reinforcements= of the FRP layer, which includes a combination of continuous rovings; fabrics- and mats; are continuously laid above the sanded surface of the laminatedwood. 20: as: it, is moved over a roller conveyor: A release sheet, is laid over the wet:~ FRP' layer. The laminated wood 21M is pushed into a gap between two sets: of rollers; one~ abov& the: other. The top rollers, are hot and in direct contact-with the release sheet covering the- wet reinforcement FRP layer. The FRP is compacted and 323.5489 USQ
bonded to the laminated wood 20 due to the heat and pressure applied on it by the top rollers. The reinforced composite floor thus formed is continuously pulled out of the roller press at the end of the roller conveyor. It will be understood that the laminated wood 20, as shown in Fig. 4a, is converted to a laminated wood board 16, as shown in Fig. 6, after the FRP 17 layer is applied and after the laminated wood. 20 with FRP 17 is machined conventially to form shiplaps 18- and crusher beads 1% thereon.
Process III for Embodiments I(Fi4. 6) and II (Fia. 7):
A laminated wood floor board 16 with shiplaps 18 and crusher beads 19 are fabricated by the conventional process set forth above. A prefabricated FRP flat sheet is then adhesively bonded. to the. bottom side of the board. to produce a reinforced composite floor board in accordance with Embodiment I. The laminated wood board is sanded on one side to develop a. flatter surface than that provided by planing. The FRP
sheet is also sanded on one side to render it flat and. clean for bonding_ An adhesive is coated on the sanded side of the board and/or the FRP. The edges of the FRP
are-aligned along the edges of the wood board. The- FRP is bonded to wood board using a platen press or rollers that can apply pressure. Heat- is applied. on the: FRP
to cure the adhesive in the case of thermosetting.=adhesives such- as epoxy, polyurethane and phenolic. For thermoplastic adhesives, the combination of the FRP and: wood board is compacted using pressure rollers with cooling. The- FRP' is fabricated with continuous fibers in the form of continuous- rovings- and fabrics. Preferably, mats- are.
not used. in this case. About 70% to about 100%" of` the.fiber reinforcement is aligned along the longitudinal direction while the remainingfibers are aligned along the lateral direction of the FRP/floor board. Altematively, a. pultruded: FRP with a U-shaped cross-section is bonded to the bottom and opposite left and right- sides of- the board to produce a reinforced composite floor in accordance-with Embodiment 11. An adhesive is-applied on the preformed, U-shaped FRP and- the sanded bottorrr surface of the floor board. The bonding of the FRP to the board: is, don& under pressure in a hotpress. or by using compaction rollers. Chamfers are: providedalongthe>lefkand right bottom comers 28 of the floor boards to easetheirassembly inta the': U-shaped:FRP panels: as~
shown in Fig.
7. The space betweerr the- insidw comers of the U-shaped FRPIan& the chamfered bottom comers 28: of the= wood: floor boarcl: help: to; hoid excess; adhesive that may be squeezed-out during the: bondingoperatiorr.CA 02306308 2000-04-20 323.5489 USQ
Process IV for Embodiments I(Fia. 6). II (Fig. 7). and III (Fio. 8):
A laminated wood board 16 is constructed according to the conventional method set forth above. The FRP layer is then fabricated and simultaneously bonded to the board, with or without conventional shiplaps,- by laying the resin-wetted reinforcements, comprising a combination of the strand mats 30, fabrics 31, and continuous rovings on the sanded surface of the laminated wood board 16 and pulling the combination together through a heated die. This process is an adaptation of the pultrusion process which normally involves the pulling of resin-wetted:
reinforcements through a heated die. The FRP is formed in correspondence to the shape of the die while the resin is cured in the die.
A 20 foot long composite wood floor kit~ consisting of eight floor boards was fabricated according to Process I as detailed above. The laminated wood was made of red and white oak strips which were edge-glued using urea-melamine fonnaldehyde"adhesive. About 50 oz/sq yd of E-glass reinforcements were used in the form of woven rovings and continuous strand mats to fabricate the reinforced:
composite - wood floor boards. A resin system consisting of Bisphenol-A epoxy resin, a reactive diluent, flexibilizer and an amine curing agent was used to bind. the reinforcements, and bond them to the laminated wood. The finished thickness of the reinforced composite wood floor was about 1,.19 inches.
In testing the reinforced composite wood floor of the invention; eight reinforced composite wood floor boards were installed in a van trailer after removing, a 20 foot section of its existing wood flooring close to the central part of the trailer. The floor was supported by I-beam cross-members running along the width of the traiierand regulariy spaced at 12 inches in the test section. The cross-members with-asectiorr of 4 inches by 2.25 inches were made of steel with a yield strength of 80 ksi andweighing, about 3.2 Ibs/foot The floor boards were secured. to each cross-member in the-test-section by three screws running through the thicknesses of the- boards: and the_ top flange of the cross-member. A lift truck simulator with two loading wheels;
and: two~
steering wheels was stationed on the floor. The: simulator was: loaded: wittr.
dea&
weights so that a force of about 16,500 lbs could be applied on the-floorthrougfrthe4 323.5489 USQ
loading wheels. The force applied on the floor through the steering wheels was relatively insignificant. To subject the floor to fatigue loading, the simulator was moved back and forth on the floor such that the loading wheels could travel about 13 feet in each direction in the central portion of the composite floor. The simulator was allowed to complete 3,000 fatigue loading cycles, wherein during each cycle the simulator moved by 13 feet in one direction and retumed back to its starting line. At the end of 3,000 fatigue loading cycles, the reinforced composite floor experienced little or no significant damage.
In another test, a 0.125-inch thick, two-inch wide and about 98-inch long steel shim was used between the cross-members and the reinforced composite floor.
As before, the floor system was tested at 16,500 lbs. At the completion of 3,000 fatigue cycles at the load of 16,500 Ibs, the simulatorwas reconfigured so as to apply a force of about 23,000 lbs on the floor: Once again, the simulator was moved back and forth to complete another 3,000-fatigue cycles at the high load. The reinforced composite wood floor was checked: to. determine the level of damage due to the repeated loading or fatigue. There was no significant breakage or fracture of the floor on its underside.
The glass fibers were intact; although wood. seemed to have fractured on the top side of the: floor near some of the shiplaps. The motion of the simulator was unaffected. at all times during the-test: There were no holes or splinters on the bottom side of the floor.
A conveRtional oak floorwith a nominal thickness of 1.38" was tested: in a trailer by repeating the above-mentioned fatigue test procedure. The wood floor was laid. directly: over the: cross-members. On. the completion of 3,000 fatigue cycles at 16;500 Ibs of loading, the. conventional oak floor showed some damage in the form of cracking. of edge=. glue: lines and pop-out of lumber strips near some of the hook joints.
Slight: fracture of lumber strips was- also noticed at a few locations. When the fatigue test- was continued: at ar increased: load of 23,000 lbs., the floor experienced severe damage- everr in the first 200 fatigue cycles. The floor was seen to fracture at several locations:and.produce:asignificantamountof cracking noise. After about 400 cycles at 23,00Q Ibs:, the floor appeared to have little or no strength and stiffness at locations between- some adjacent'cross=members:At this time, the simulator wheels essentially roiled averthe: cross-members; and: dived in and out of the pits created due to the severely. damaged: floor sections This- caused considerable shaking and vibration in 323.5489 USQ
the trailer due to a bumpy path created by broken floor sections. Clearly, the conventional oak floor failed the test and therefore proved to be much inferior to the composite wood flooring.
It was clear from the above-mentioned tests that a 1.19" thick reinforced composite wood flooring weighing about 4.9 lbs/sq ft could be superior to a 1.38" thick conventional wood flooring weighing about 5.4 lbs/sq ft. The reinforced composite floor can be used in trailers to sustain nominal lift truck loads of 16,500 lbs while saving about half pound of weight per square foot of the floor. In addition, with slight modification of the design of the cross-members, the load carrying capacity of the truck floor system can be increased considerably with little or no increase in the weight of the trailer. The excellent fatigue resistance of the reinforced composite flooring is essentially due to the ability of the FRP underlayer to prevent the pop-out of the lumber strips. The hook joints are completely covered on the bottorrr side of the floor and therefore water cannot penetrate through their gaps into the trailer. Due to the higher strength of the reinforced composite wood floor, its thickness can be reduced below that of an equivalent conventional wood floor. This in tum can lead to a significant weight saving in a trailer and hence increase its cargo carrying capacity.
Claims (29)
1. A composite vehicular trailer flooring system having an exposed wood upper surface, the vehicular trailer floor having a longitudinal length and a lateral width, said composite vehicular trailer flooring system comprising:
a plurality of wood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each wood board of said plurality of wood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each wood board being formed of a plurality of wood segments joined to one another by coupling portions;
said plurality of wood boards being arranged such that at least one of said first side surface and said second side surface of each of said wood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper wood surface and a bottom surface for extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
each of the plurality of wood boards of said composite wood flooring system further comprising a substantially planar polymer layer formed of a fiber reinforced polymer, said polymer layer being substantially continuously bonded to said bottom surface of each of the plurality of wood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each wood board, the upper wood surface of each of the plurality of wood boards being essentially uncoated by fiber reinforced polymer, and wherein from 90% to 100% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor, and the fibers are glass fibers, carbon fibers, or mixtures thereof; and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of wood boards of the trailer floor resists pop-out of the wood segments at the coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the vehicular trailer floor.
a plurality of wood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each wood board of said plurality of wood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each wood board being formed of a plurality of wood segments joined to one another by coupling portions;
said plurality of wood boards being arranged such that at least one of said first side surface and said second side surface of each of said wood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper wood surface and a bottom surface for extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
each of the plurality of wood boards of said composite wood flooring system further comprising a substantially planar polymer layer formed of a fiber reinforced polymer, said polymer layer being substantially continuously bonded to said bottom surface of each of the plurality of wood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each wood board, the upper wood surface of each of the plurality of wood boards being essentially uncoated by fiber reinforced polymer, and wherein from 90% to 100% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor, and the fibers are glass fibers, carbon fibers, or mixtures thereof; and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of wood boards of the trailer floor resists pop-out of the wood segments at the coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the vehicular trailer floor.
2. The composite wood flooring system of claim 1, wherein said wood is ash, yellow-poplar, elm, oak, maple, birch or beech.
3. The composite wood flooring system of claim 1, wherein said coupling portions comprise hook joints.
4. The composite wood flooring system of claim 1, wherein said first side surface is provided with an upper lip portion, said second side surface is provided with a lower lip portion, and approximation of said first side surface of one of said wood boards with said second side surface of an adjacent wood board forms a shiplap joint in which said upper lip portion at least partially overlies said lower lip portion.
5. The composite wood flooring system of claim 4, wherein at least one of said first side surface and said second side surface is further provided with a bead to prevent said upper lip portion of said first side surface from fully overlying said lower lip portion of said second side surface of an adjacent board to form a gap at the site of said shiplap joint.
6. The composite wood flooring system of claim 4, wherein said coupling portions comprise hook joints and said polymer layer underlies substantially all of said hook joints of said trailer floor.
7. The composite wood flooring system of claim 5, wherein said polymer layer underlies substantially all of said shiplap joints of said trailer floor.
8. The composite wood flooring system of claim 1, wherein said fiber reinforced polymer layer comprises rovings of continuous fibers impregnated by a polymeric resin.
9. The composite wood flooring system of claim 1, wherein said fiber reinforced polymer layer comprises one or more strand mat impregnated by a polymeric resin.
10. The composite wood flooring system of claim 1, wherein about 70% to 90% of said continuous fibers extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor.
11. The composite wood flooring system of claim 1, wherein the polymer of the fiber reinforced polymer is vinyl ester, polyester, epoxy, phenolic, polypropylene, or polyamide polymers.
12. The composite wood flooring system of claim 1, wherein the fiber reinforced polymer comprises a combination of continuous rovings and one or more fabrics of reinforcing fibers impregnated by a polymeric resin.
13. The composite wood flooring system of claim 1, wherein said fiber reinforced polymer comprises one or more fabrics of reinforcing fibers which fabric is woven rovings, stitched fabrics or knitted fabrics.
14. The composite wood flooring system of claim 1, wherein said coupling portions comprise butt joints, finger joints or lap and gap joints.
15. In a hardwood vehicular trailer flooring system having an exposed hardwood upper surface, the vehicular trailer floor having a longitudinal length and a lateral width comprising:
a hardwood layer including a plurality of hardwood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each hardwood board of said plurality of hardwood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each hardwood board being formed of a plurality of hardwood segments joined to one another by shaped coupling portions;
said plurality of hardwood boards being arranged such that at least one of said first side surface and said second side surface of each of said hardwood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper hardwood surface and a bottom surface extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
the improvement comprising the compositing of said hardwood layer with a substantially planar polymer layer formed of a fiber reinforced polymer substantially continuously bonded to said bottom surface of each of the plurality of hardwood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each hardwood board, the upper hardwood surface of each of the plurality of hardwood boards being essentially uncoated fiber reinforced polymer, and from 90% to 100% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor and the fibers are glass fibers, carbon fibers, or mixtures thereof;
and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of hardwood boards of the trailer floor resists pop-out of the hardwood segments at the shaped coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the trailer floor.
a hardwood layer including a plurality of hardwood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each hardwood board of said plurality of hardwood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each hardwood board being formed of a plurality of hardwood segments joined to one another by shaped coupling portions;
said plurality of hardwood boards being arranged such that at least one of said first side surface and said second side surface of each of said hardwood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper hardwood surface and a bottom surface extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
the improvement comprising the compositing of said hardwood layer with a substantially planar polymer layer formed of a fiber reinforced polymer substantially continuously bonded to said bottom surface of each of the plurality of hardwood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each hardwood board, the upper hardwood surface of each of the plurality of hardwood boards being essentially uncoated fiber reinforced polymer, and from 90% to 100% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor and the fibers are glass fibers, carbon fibers, or mixtures thereof;
and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of hardwood boards of the trailer floor resists pop-out of the hardwood segments at the shaped coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the trailer floor.
16. The composite hardwood flooring system of claim 15, wherein said wood is ash, yellow-poplar, elm, oak, maple, birch or beech.
17. The composite hardwood flooring system of claim 15, wherein said shaped coupling portions comprise hook joints.
18. The composite hardwood flooring system of claim 15, wherein said first side surface is provided with an upper lip portion, said second side surface is provided with a lower lip portion, and approximation of the first side surface of one of said hardwood boards with said second side surface of an adjacent hardwood board forms a shiplap joint in which said upper lip portion at least partially overlies said lower lip portion.
19. The composite hardwood flooring system of claim 18, wherein at least one of said first side surface and said second side surface is further provided with a bead to prevent said upper lip portion of said first side surface from fully overlying said lower lip portion of said second side surface of an adjacent board to form a gap at the site of said shiplap joint.
20. The composite hardwood flooring system of claim 18, wherein said coupling portions comprise hook joints and said polymer layer underlies substantially all of said hook joints of said trailer floor.
21. The composite hardwood flooring system of claim 19, wherein said polymer layer underlies substantially all of said shiplap joints of said trailer floor.
22. The composite hardwood flooring system of claim 15, wherein the polymer of the fiber reinforced polymer is vinyl ester, polyester, epoxy, phenolic, polypropylene, or polyamide polymers.
23. The composite hardwood flooring system of claim 15, wherein the fiber reinforced polymer comprises a combination of-continuous rovings and one or more fabrics of reinforcing fibers impregnated by a polymeric resin.
24. The composite hardwood flooring system of claim 15, wherein said fiber reinforced polymer layer comprises rovings of continuous fibers impregnated by a polymeric resin.
25. The composite hardwood flooring system of claim 15, wherein said fiber reinforced polymer layer comprises one or more strand mats impregnated with a polymeric resin.
26. The composite hardwood flooring system of claim 15, wherein said coupling portions comprise butt joints, finger joints or lap and gap joints.
27. The composite hardwood flooring system of claim 15, wherein said fiber reinforced polymer comprises one or more fabrics of reinforcing fibers which fabric is woven rovings, stitched fabrics or knitted fabrics.
28. A composite vehicular trailer flooring system having an exposed wood upper surface, the vehicular trailer floor having a longitudinal length and a lateral width, said composite vehicular trailer flooring system comprising:
a plurality of wood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each wood board of said plurality of wood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each wood board being formed of a plurality of wood segments joined to one another by coupling portions;
said plurality of wood boards being arranged such that at least one of said first side surface and said second side surface of each of said wood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper wood surface and a bottom surface for extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
each of the plurality of wood boards of said composite wood flooring system further comprising a substantially planar polymer layer formed of a fiber reinforced polymer, said polymer layer being substantially continuously bonded to said bottom surface of each of the plurality of wood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each wood board, the upper wood surface of each of the plurality of wood boards being essentially uncoated by fiber reinforced polymer, and wherein from 70% to 90% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor, and the fibers are glass fibers, carbon fibers, or mixtures thereof; and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of wood boards of the trailer floor resists pop-out of the wood segments at the coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the vehicular trailer floor, wherein the wood is ash, yellow-poplar or elm.
a plurality of wood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each wood board of said plurality of wood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each wood board being formed of a plurality of wood segments joined to one another by coupling portions;
said plurality of wood boards being arranged such that at least one of said first side surface and said second side surface of each of said wood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper wood surface and a bottom surface for extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
each of the plurality of wood boards of said composite wood flooring system further comprising a substantially planar polymer layer formed of a fiber reinforced polymer, said polymer layer being substantially continuously bonded to said bottom surface of each of the plurality of wood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each wood board, the upper wood surface of each of the plurality of wood boards being essentially uncoated by fiber reinforced polymer, and wherein from 70% to 90% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor, and the fibers are glass fibers, carbon fibers, or mixtures thereof; and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of wood boards of the trailer floor resists pop-out of the wood segments at the coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the vehicular trailer floor, wherein the wood is ash, yellow-poplar or elm.
29. In a hardwood vehicular trailer flooring system having an exposed hardwood upper surface, the vehicular trailer floor having a longitudinal length and a lateral width comprising:
a hardwood layer including a plurality of hardwood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each hardwood board of said plurality of hardwood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each hardwood board being formed of a plurality of hardwood segments joined to one another by shaped coupling portions;
said plurality of hardwood boards being arranged such that at least one of said first side surface and said second side surface of each of said hardwood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper hardwood surface and a bottom surface extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
the improvement comprising the compositing of said hardwood layer with a substantially planar polymer layer formed of a fiber reinforced polymer substantially continuously bonded to said bottom surface of each of the plurality of hardwood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each hardwood board, the upper hardwood surface of each of the plurality of hardwood boards being essentially uncoated fiber reinforced polymer, and from 70% to 90% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor and the fibers are glass fibers, carbon fibers, or mixtures thereof;
and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of hardwood boards of the trailer floor resists pop-out of the hardwood segments at the shaped coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the trailer floor, wherein the hardwood is ash, yellow-poplar or elm.
a hardwood layer including a plurality of hardwood boards extending longitudinally up to a length substantially equal to the longitudinal length of said vehicular trailer floor, each hardwood board of said plurality of hardwood boards having a top surface, a bottom surface opposite said top surface, and a first side surface and second side surface extending between said top surface and said bottom surface, and a board width that is less than the lateral width of said vehicular trailer floor, each hardwood board being formed of a plurality of hardwood segments joined to one another by shaped coupling portions;
said plurality of hardwood boards being arranged such that at least one of said first side surface and said second side surface of each of said hardwood boards approximates one of said first side surface and said second side surface of adjacent boards or a mating portion of a metallic component of the trailer to form a continuous trailer floor having an upper hardwood surface and a bottom surface extending for the lateral width of the vehicular trailer floor, a joint region being formed at locations at which said first side surface or said second side surface of adjacent boards approximate one another;
the improvement comprising the compositing of said hardwood layer with a substantially planar polymer layer formed of a fiber reinforced polymer substantially continuously bonded to said bottom surface of each of the plurality of hardwood boards of said trailer floor and extending unitarily substantially across the width and along the longitudinal length of each hardwood board, the upper hardwood surface of each of the plurality of hardwood boards being essentially uncoated fiber reinforced polymer, and from 70% to 90% of the fibers of said fiber reinforced polymer extend in a direction substantially parallel to the longitudinal length of the boards of the trailer floor and the fibers are glass fibers, carbon fibers, or mixtures thereof;
and whereby said substantially continuous planar polymer layer of fiber reinforced polymer bonded to the bottom surface of each of the plurality of hardwood boards of the trailer floor resists pop-out of the hardwood segments at the shaped coupling portions and improves one or more of the flexural modulus, strength and load carrying capacity of the trailer floor, wherein the hardwood is ash, yellow-poplar or elm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/294,476 | 1999-04-20 | ||
| US09/294,476 US6183824B1 (en) | 1995-06-07 | 1999-04-20 | Composite wood flooring |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2306308A1 CA2306308A1 (en) | 2000-10-20 |
| CA2306308C true CA2306308C (en) | 2009-02-24 |
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ID=23133609
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002306308A Expired - Lifetime CA2306308C (en) | 1999-04-20 | 2000-04-20 | Composite wood flooring |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004098876A1 (en) * | 2003-05-09 | 2004-11-18 | Chong Chee Tan | Reinforced lumber and production thereof |
| CN107985160A (en) * | 2016-10-27 | 2018-05-04 | 上海杰事杰新材料(集团)股份有限公司 | Lorry compartment floor and preparation method thereof |
| WO2021080917A1 (en) * | 2019-10-24 | 2021-04-29 | Zephyros, Inc. | Pultruded and continuous flooring |
| CN113211566B (en) * | 2021-05-11 | 2022-07-15 | 柳州市东阳木业有限公司 | Automatic processing system and method for plywood production |
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2000
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