MXPA06004525A

MXPA06004525A - Method and apparatus for maintaining filaments in position in a filament winding process.

Info

Publication number: MXPA06004525A
Application number: MXPA06004525A
Authority: MX
Inventors: Bruce L Elliott
Original assignee: Resin Systems Inc
Priority date: 2003-10-22
Filing date: 2004-10-18
Publication date: 2006-06-23
Also published as: CN1871116A; CA2444324A1; US20070125487A1; WO2005037527A1; AU2004281861A1; KR20060111453A

Abstract

A method for maintaining filaments in position when manufacturing composite parts through a filament winding process. In its most basic form the method includes a first step of applying resin impregnated filament (16) onto an elongate mandrel (12). A second step is involved of winding yarn (32) onto the elongate mandrel (12) overlying the resin impregnated filament (16), to maintain the resin impregnated filament (16) in position and under tension.

Description

METHOD AND APPARATUS FOR MAINTAINING FILAMENTS IN POSITION IN A FILAMENT WINDING PROCESS Field of the Invention The present invention relates to a method of maintaining filaments in position when manufacturing composite parts by a filament winding process and an apparatus constructed to implement the teachings of the method. Background of the Invention Published patent application CA 2,274,328 (Elliott 1999) describes a problem encountered in winding processes of filaments of resin-coated filament fibers that slide out of the mold during winding of the filaments. The solution proposed by Elliott was to roll the dry filament over the surface of the mold and then subsequently infuse resin into the dry filament. This dry filament winding has found limited success, but is not always adequate. SUMMARY OF THE INVENTION What is required is a method and apparatus for maintaining filaments in position when manufacturing composite parts by a filament winding process. According to one aspect of the present invention there is provided a method for maintaining the filaments in position when manufacturing composite parts by a filament winding process. In its most basic form, the method includes a first step of applying filament impregnated with resin on an elongated mandrel. A second step is involved, which is to wind yarn in the elongated mandrel covering the resin-impregnated filament, to keep the filament impregnated with resin and under tension in position. Once the basic method is understood, there are various ways to further refine the process, as will be evident from the full description of the method that follows. In accordance with another aspect of the present invention, an apparatus is provided for maintaining filaments in position when manufacturing composite parts by a filament winding process. In its most basic form, the apparatus includes a mandrel together with means for selectively rotating the mandrel. A ring is provided that is co-axial with and surrounds the mandrel. A spool of yarn or multiple spools are mounted on the ring. Means are provided for causing the reel to orbit the mandrel and thereby apply yarn circumferentially to the mandrel. Once the basic apparatus is understood, there are additional aspects that can be added, as will be evident from the full description of the apparatus that follows. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the invention will be apparent from the following description, in which reference will be made to the accompanying drawings, the drawings being for the purpose of illustration only and are not intended to limit in any way the Field of the invention to the particular form or embodiments shown, wherein: Figure 1 is a perspective view of an apparatus for maintaining filaments in position in a filament winding process, shown in use for unidirectional winding in accordance with teachings of the preferred method; Figure 2 is a perspective view of the apparatus illustrated in Figure 1, shown at the end of a unidirectional winding step; Figure 3 is a perspective view of the apparatus illustrated in Figure 1, shown in use for angular winding; Figure 4 is a side elevational view of the apparatus illustrated in Figure 3, shown at the end of an angular winding forward pitch; Figure 5 is a side elevational view of the apparatus illustrated in Figure 3, shown at the end of an angular winding return passage; Figure 6 is a detailed side elevational view of the apparatus illustrated in Figure 1, shown in use with unidirectional winding; Figure 7 is a side elevational view, detailed, of the apparatus illustrated in Figure 1, shown in transition deviating from unidirectional winding; Figure 8 is a detailed side elevational view of the apparatus illustrated in Figure 1, shown in use with angular winding; and Figure 9 is an end elevation of the apparatus shown in use for unidirectional winding. Detailed Description of the Preferred Embodiment The preferred apparatus, generally identified by the reference numeral 10, and the preferred method will now be described with reference to Figures 1 to 9. Structure: First, the apparatus 10 which was developed will be described. to maintain filaments in position when composite parts are manufactured by a filament winding process. The apparatus 10 includes an elongate mandrel 12. At least one impregnation box 14 is provided. In the illustrated embodiments, two have been shown. Each impregnation box is adapted to wet strand 16 with resin 18 before the application of the filament 16 in the mandrel 12. Guide rollers 20 are provided to control the application of the filament 16 in the mandrel 12. Means are provided for selectively rotating the mandrel 12. As the means are well known in the art , are not illustrated, but are indicated by the arrow 22. As will be described hereinafter with reference to the method, by turning the mandrel 12 selectively the orientation of the filaments 16 can be altered. Collars 24 with projecting peaks 26 are provided, which provide separation points and anchor e for the first torsion, particularly when it is oriented on or near the axis. In larger mandrels, collars with spikes can be replaced by slits in the mandrel, which perform the same function. The collars 24 are positioned in spaced relation in the mandrel 12. The collars 24 are adapted to help maintain the placement and separation of filaments by segregating filaments 16 with projecting peaks 26. A ring 28 is provided, which is co-ordinate. axial with and surrounds the mandrel 12. A spool 30 containing thread 32 is mounted on the ring 28. Means are provided for rotating the ring 28 about its axis. As a person skilled in the art would be aware of suitable means for turning the ring 28, they have not been illustrated. The rotation of the ring 28 is indicated by the arrow 34. The rotation of the ring 28 causes the spool 30 to orbit the mandrel 12, thereby applying yarn 32 circumferentially to the mandrel 12 covering the filament 16 to maintain the filament 16 in position, as it will be described further in the following. Method: The first twist or filament belt is pulled through an impregnation box, which opens the filaments and aligns and controls the separation of the first twist (figure 1). The first aligned torsion then proceeds through a resin bath and outwards via a series of rollers. The effect of the guide rollers is to facilitate wetting out by forcing the resin towards the filaments of the open twisted fibers. Subsequent rollers maintain tension and squeeze the excess resin onto the fiberglass. The result is a first open, aligned, tensioned torsion, which has had the filaments, has been wetted by the resin and the excess resin has been removed. By setting guide configurations and roller angles, the path of the first twist can be altered. This allows control and adjustment of the first torsion for alignment, separation, tension and the degree of impregnation in relation to the resin. There are several ways in which the impregnation box can be used to impregnate the first twist of filament with resin. One way is to inject the resin, such as polyurethane, directly into the first twist at the inlet of the impregnation box and allow the rollers to work and squeeze out the excess resin. In this case, the resin in the resin tray is as a direct result of the excess that is being squeezed out of the first twist. In another method, the resin tray is filled with a liquid resin, such as epoxy polyester or vinyl ester and the resin is allowed to impregnate the first torsion by the action of immersion together with the effects of the rollers, which serve to moisturize and to squeeze any excess. In this way, resins with short life in the container can be used via resin injection and resins with longer life in the container can be used using a more conventional resin bath immersion technique. A third embodiment is to use first twist or pre-impregnated tape, consisting of resin and a fibrous reinforcement such as Twintex, which is a co-shredded glass and polypropylene material. In this case the glass, the resin and the fibrous reinforcement (first twist) would simply exceed the impregnation stage, since the resin is already part of the first twist. The first twist or tape would then proceed through the guide rollers in the same manner as the wet roll; however, in this case the material would be dry. Each impregnation box (14) is mounted on the first torsion carriage (36) and is responsible for delivering a series of individual first filament twists via the guide rollers (20) that have been separated, tensioned and wetted outwards and it is referred to as a head (figure 9). The device is constructed so that multiple heads operate together, delivering a series of first twist of filament in the mandrel, showing two in Figure 9.

The cycle typically starts with an initial circumferential wrapping of the first twist on the mandrel, which is located outside the winding area. This acts as an anchor point so that the first filament twist can generate tension during winding. In one embodiment, the head that delivers the first filament twist now moves down the mandrel and the trajectory of the first twist advances on a spiked collar. This collar maintains the position of the first torsion on the mandrel. In another embodiment, the carriage (36) is stationary and the mandrel is moved back and forth. At the end of the pass another circumferential wrap of the first twist is again carried out to act as an anchor point so that the first twist is maintained in position and tension, as shown in Figure 2. During the process of unidirectional winding, a yarn made from materials such as mono-filament polymer, glass, carbon or aramid, is wrapped over the filaments (figures 1 and 6). The spool of thread is attached to a ring that can move along the length of the mandrel and turn (Figures 1 and 2). The number of wraps, together with the wrapping angle, can be predetermined so as to provide maximum stability to the filament winding by programming the rate of displacement and the rate of rotation of the ring, which in turn houses the spool of yarn. In order to produce the circumferential winding, the head traverses down the length of the mandrel while the mandrel is rotated. By adjusting the speed of displacement to the rotation speed, the first torsion can be wrapped at angles varying from 90 to 0 degrees. The circumferential windings are usually quite stable and do not require over-wrapping, as shown in Figures 3, 4, 5 and 8. Figure 6 denotes the axis reference. When axial fibers are placed on a mandrel, a thread or a single filament is delivered to one or more spools used to hold them in place against slip (Figures 1 and 2). This is done by having two rotating rings (one on each side of the heads, as shown in figure 1) with fiber spools (for example: first glass twist, Kevlar, acrylic yarn, nylon mono-filament, etc.). ) and movable arms with ceramic eyelets (33). These are attached to each side of the fiber placement head, allowing the machine to use the back ring to apply a fiber cord around the mandrel to pull the axial fibers onto the mandrel. The magnitude of the tension can be adjusted as desired by adjusting the tension on the reel. One or more heads are used to apply the fibers (figures 1, 2, 3 and 9, which show a configuration of two heads). The fiber placement heads have a PLC control to allow them to accurately position the guide rollers (20) as they move along the mandrel. This control of the position of the heads allows them to increase or reduce the bandwidth of the first filament twists when axial fiber is applied by adjusting the distance to which the head is from the mandrel. The guide rollers (20) can pivot at any angle between vertical and horizontal, which can also be used to control the spacing between individual fiber filaments by rotating the head when deploying axial fiber. Figures 1 and 2 show the vertical position and Figure 3 shows the horizontal position. The device has complete control over all axes. The mandrel can be rotated in any direction or stopped in a pre-defined position to place fiber. The layers can be applied with all the fiber in one direction (Figures 4 and 5) by rotating the mandrel in the opposite direction to the last pass to fill the free spaces until a full coat is applied. A geodetic winding can also be wound. In this patent document, the word "comprising" or "comprising" is used in its non-limiting sense to mean that articles that follow the word are included, but articles not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that it is present -limas of an element, unless the context clearly requires that there be one and only one of the elements. It will be apparent to a person skilled in the art that modifications can be made to the illustrated embodiment without departing from the spirit and scope of the invention, as will be defined hereinafter in the claims.

Claims

CLAIMS 1. A method for maintaining filaments in position when manufacturing composite parts by means of a filament winding process, comprising the steps of: applying a filament impregnated with resin (16) onto an elongated mandrel (12); and winding yarn (32) on the elongated mandrel (12) covering the filament impregnated with resin (16), to keep the filament impregnated with resin (16) in position and under tension.
2. The method defined in claim 1, the steps being repeated sequentially by applying alternating layers of filament impregnated with resin (16) followed by yarn (32) to maintain each layer of filament impregnated with resin (16) in position and under tension.
3. The method defined in claim 1, placing collars (24) with projecting peaks (26) in spaced relation in the mandrel (12) to help maintain the placement and spacing of the filament, the filament (16) extending between the respective collars (24), maintaining the spacing between filaments segregating the filaments (16) with the projected peaks (26).
4. The method defined in claim 1, slits being placed in spaced relation in the mandrel (12) to help maintain the placement and spacing of filament.
5. The method defined in claim 1, including the step of wrapping a circumferential wrap of filaments (16) around the mandrel (12) at the end of each pass in order to anchor the filament (16).
6. The method defined in claim 1, at least one ring (28) being provided, which is coaxial to and surrounds the mandrel (? 2), the wire (32) · being placed on a reel (30), which is mounted on the ring (28), the spool (30) orbiting the mandrel (12) to apply yarn (32) circumferentially to the mandrel (12).
7. The method defined in claim 6, wherein more than one ring (28) is provided.
8. The method defined in claim 6, the spool (30) being fixed in position on the ring (28) and the ring (28) rotating about its axis.
The method defined in claim 6, with guides (33) being provided to guide the wire path (32) upon leaving the spool (30).
10. The method defined in claim 9, the guides (33) being supported by a support arm.
11. The method defined in claim 1, the orientation of the filament being controlled by selectively rotating the mandrel (12).
12. The method defined in claim 1, the mandrel (12) being moved axially.
13. The method defined in claim 6, the at least one ring (28) being moved axially along the mandrel (12). The method defined in claim 1, wherein at least one impregnation box (14) is provided to impregnate the filament (16) with resin. The method defined in claim 1, wherein guide rollers (20) are provided to control the application of the filament (16).