Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-12-30
2001-01-30
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S169000
Reexamination Certificate
active
06179945
ABSTRACT:
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
This invention relates to a process and apparatus for filament winding composite workpieces and, more particularly, to such a process and apparatus wherein reinforcement material is impregnated in an injection die prior to being wound onto a mandrel.
BACKGROUND OF THE INVENTION
When making filament wound parts or workpieces, continuous fibers are conventionally wound onto a mandrel in predetermined geometric patterns using winding equipment. Creels hold the fibers and they are fed under tension. The mandrel may rotate or be passive. The orientation and thickness of the winding may be selected to match the direction and magnitude of loads in the final part or workpiece.
Typically high strength reinforcing or structural fibers such as fiberglass, e.g., E glass or S glass, and aramid, boron and carbon fibers, may be used when making filament wound parts or workpieces. The fibers are impregnated with a liquid resin, such as a polyester or an epoxy resin, via an impregnation bath or a roll applicator. The fibers are wetted before they are wound onto the mandrel. To obtain wetting, the fibers are typically drawn through an impregnation bath or passed over an applicator roll. Wetting and fill impregnation are difficult to achieve with these traditional methods. Further, these methods often result in air being trapped in the wetted reinforcement bundle. Even at slow speeds, these conventional wetting processes are only capable of wetting, impregnation and air removal of a limited number of strands. Hence, the rate of reinforcement material application which may be incorporated within filament wound parts is limited. Further, filament wound parts are made at relatively low rates due to the slow rate of wetting, making such parts expensive.
Resin baths are open or partially open to the atmosphere resulting in significant emissions into the atmosphere of environmentally unfriendly volatile organic compounds or VOC's. Further, significant resin waste commonly occurs with the use of open bath wet-out methods.
Voids are commonly found in filament wound parts which are caused by air becoming entrapped in the resin loaded onto the fibers as they pass through a resin bath or engage a roll applicator.
Hence, there is a need for an improved filament winding process and apparatus whereby: 1) higher application rates of glass reinforcement material can be wetted to reduce the time required to form a filament wound part; 2) filament wound parts can be formed with a higher reinforcement content; 3) voids in final workpieces can be reduced; 4) VOC emissions can be reduced; and 5) improved resin utilization occurs.
SUMMARY OF THE INVENTION
The present invention provides an improved process and apparatus for filament winding parts or workpieces. It involves passing reinforcement material, prior to being wound onto a mandrel, through a high pressure injection die wherein the reinforcement material is impregnated with resin material. The injection die is capable of increasing the rate of reinforcement application while providing complete impregnation of the reinforcement material. Further, reinforcement material packs having increased thicknesses and densities, which heretofore, were not used in filament winding processes, can now be used. Also, resin materials having high viscosities which if used in an impregnation bath would not have resulted in full impregnation within a reasonable time period, can now be used. The parts or workpieces formed by the process and apparatus of the present invention have a reduced number of voids. Further, fewer VOC's are released into the atmosphere since an open resin bath is not required.
In accordance with a first aspect of the present invention, a process is provided Or filament winding a composite workpiece. The process comprises the steps of: providing reinforcement material; providing an injection die; providing a winding apparatus including a rotatable mandrel; passing the reinforcement material through the injection die; injecting a resin material into the injection die to impregnate the reinforcement material with the resin material to form impregnated reinforcement material; and winding the impregnated reinforcement material about the mandrel so as to form a composite workpiece.
The reinforcement material may comprise continuous fibers alone or in combination with roll goods. The roll goods may comprise woven, non-woven and needle-punched fabrics, chopped strand mat, veil or a combination thereof.
In one embodiment, where the reinforcement material comprises continuous fibers in combination with roll goods, the continuous fibers are under a first tension as they pass through the injection die and are wound onto the mandrel, and the roll goods are under a second tension as they pass through the injection die and are wound onto the mandrel. The second tension is less than the first tension which allows the roll goods to be incorporated in a filament winding process.
The step of injecting a resin material into the injection die may comprise the step of injecting a single resin into the injection die. Alternatively, first and second resins may be injected into the injection die. The first resin may impregnate a lower portion of the reinforcement material and the second resin may impregnate an upper portion of the reinforcement material. The first resin may comprise a corrosion resistant resin while the second resin comprises a less costly resin. It is also contemplated that the first or the second resin system may include an abrasion resistant filler, an ultraviolet degradation inhibitor or other functional additives with features that are advantageous to a portion of the total laminate buildup.
In accordance with a second aspect of the present invention, an apparatus is provided for filament winding a composite workpiece. The apparatus comprises apparatus for supplying reinforcement material and an injection die through which the reinforcement material passes and into which resin material is injected. The resin material impregnates the reinforcement material. The apparatus further includes a winding apparatus positioned adjacent to the injection die. The winding apparatus includes a mandrel. The impregnated reinforcement material is wound about the mandrel so as to form a composite workpiece.
The supply apparatus includes a first tensioning device causing the continuous fibers to be supplied under a first tension and a second tensioning device causing the roll goods to be supplied under a second tension which is less than the first tension.
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pate
Beckman Jay Joseph
Gauchel James Vincent
Greenwood Mark Edward
Hankin Anthony Grenville
Aftergut Jeff H.
Eckert Inger H.
Owens Corning Fiberglas Technology Inc.
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