GB2152869A - Pultrusion product and process - Google Patents

Abstract

A fiberglass pultrusion includes a metal strip (48) secured thereto during the pultrusion process. The metal strip permits riveting of other pieces to the pultrusion without weakening the areas beneath the rivet upsets. The metal strip is preferably added before a curing step in which resin impregnated fibreglass roving (36) and mat (42) are passed with the metal strip through a curing die (54). <IMAGE>

Description

SPECIFICATION Pultrusion product and process Pultrusion is a continuous molding process and is well known. Glass or fibrous reinforcements in polyesters or other thermosetting resin matrices are generally employed in the process. The pultrusion process involves drawing the reinforcement materials through a resin bath where they are impregnated with a liquid thermosetting resin. Such resins may include epoxies, acrylics, polyesters or the like.

The fibrous laminate is formed to a particular shape while it is still wet and pulled into a heated die. The resin is then subjected to high temperatures in the order of several hundred degrees Fahrenheit and cured. The shape of the cavity in the die determines the shape of the pultrusion while it is being continuously pulled out of the die by a pultrusion machine.

The use of pultrusions has a number of advantages. They are generally strong enough to serve as structural members, are lighter than corresponding metal parts and generally cheaper to manufacture.

One of the uses to which pultrusions have been applied involves posts for receiving side panels in cargo containers and trailers. For example, the pultrusions may be "Z" shaped elongate members designed to serve as vertical side posts in the trailer. Side panels are riveted to the posts to form the side walls. Heretofore, the riveting of the side panels to the pultruded posts has created problems.

One of the problems was that after the rivets were inserted through the openings in the side panels and posts, upsetting the rivets caused the shanks of the rivets as well as the upset portions of the rivets to generate substantial forces against the fiberglass surfaces. This weakened the fiberglass and caused localized failures beneath the rivet upsets. Because the pultruded portions contacting the side panels comprise major load carrying areas, it is important the likelihood of failures due to rivet upsets be minimized.

There have been patents which disclose the use of different plastics in combinations with different metals. For example, U.S. Patent 3,746,388 shows a fiberglass material and aluminum skin separated by a foamed element. U.S. Patent 4,101,704 shows plastic like material mounted on metal backing plates. U.S. Patent 3,502,541 shows an aluminum foil which is coated with a solution and laminated with a film of polypropylene. U.S. Patent 4,382,626 shows a molded glass reinforced body where steel sheets are screwed onto SMC panels. None of these patents suggest making a pultrusion with aluminum embedded and secured to a fiberglass body during the manufacturing operation.

In accordance with the present invention, a pultrusion is formed by drawing a fiber reinforcement through a resin bath, shaping and heating the part formed and curing the part under high temperature. A metal material is added to the pultrusion after the resin bath and prior to the curing. The metal material forms part of the final pultrusion and facilitates the riveting of other parts to the pultrusion.

The invention is illustrated, by way of example only, by the following description of a preferred embodiment to be taken in conjunction with the accompanying drawings, in which: Figure 1 is an isometric view of a portion of a side wall of a trailer, partly broken away, illustrating the use of a pultrusion having a metal strip secured thereto in accordance with the present invention; Figure 2 is a view, partly broken away and enlarged, of a portion of the side wall illustrated in Figure 1; Figure 3 is a cross-sectional view taken along lines 3-3 of Figure 2; and Figure 4 is a view illustrating some of the main steps in a pultrusion process for forming a post having a metal strip secured to a fiberglass reinforced body.

Referring to Figures 1, 2 and 3, a trailer container comprises a side wall 16. A plurality of spaced posts 20 are connected between a roof rail 22 and a floor rail 24.

A plurality of metal sheets 26 are mounted to the posts 20 by means of rivets 28. Each of the posts 20 comprise a pultrusion made from a fiberglass reinforced resin material 21 having a metal strip 30 embedded therein. When the term embedding is used, it does not include encapsulating the metal, but only cases where the metal is partly within the pultrusion while still having a metal surface exposed to receive the forces of upset.

The pultruded posts 20 are made by a process illustrated in Figure 4, to be subsequently described.

In general, the metal strip 30, which may comprise aluminum or other suitable metal, is embedded in the resinous material prior to curing in the pultrusion process so that in effect the metal strip and the fibreglass reinforced resin form an integral piece. The metal strip 30 is put in the resin when the material is still relatively soft and prior to curing.

As illustrated in Figure 3, the metal strip 30 is partly embedded in the reinforced fiber material 21 with a portion of the strip being completely exposed so as to receive the upset portion 34 in the particular embodiment illustrated. The upset portion 34 is illustrated as being flattened although other types of rivets may be used. It is noted that if the strip 30 were completely encapsulated in the material 21, the upset portions 34 of the rivets 28 would tend to cause weakened areas in the glass reinforced fiber material which comprise major load bearing sections of the side walls of the trailer involved.

Referring to Fig. 4, the steps in making a pultrusion having a metal strip secured thereto is illustrated. Fiberglass roving 36 is passed through a resin bath 38 and through a forming die 40.

A fiberglass mat 42 is also passed through a resin bath 44. The impregnated fiberglass mat 42 is passed through a forming die 46 which also re ceives the impregnated fiberglass roving from the forming die 40. Of course, other fiberous type materials may be substituted for the fiberglass.

A roll of metal 48, which may comprise aluminum, is disposed to pass a strip of material through a cleaning solution 50. After being dried by suitable means, the strip from the roll 48 is combined with the resin impregnated fiberglass roving 36 and the resin impregnated fiberglass mat 42 and passes through a forming die 52.

The metal strip is added before the resins are cured with a "Z" shaped uncured pultrusion being then passed onto a curing die 54. The final formed pultrusion may then be passed through a cooling chamber 56. The means for pulling the formed pultrusion may include rollers or other pulling devices, not illustrated, but well known to those skilled in the art.

While the metal strip 30 formed from the roll 48 may be adhered to the material 21 during the pultrusion process, in a preferred embodiment, the strip is partly embedded in the material, as illustrated in Figure 3. The embedding holds the strip 30 more firmly in place within the pultrusion than if the strip was merely adhered to the pultrusion.

Also partly embedding the strip makes it easier to form the pultrusion because the final forming die 52 may be simplified.

It is noted that incorporating a metal strip in glass reinforced resin during a pultrusion operation makes it possible to provide a structural support member relatively inexpensively and without requiring separate operations of binding a strip to a pultrusion.

While the present invention has been described in connection with posts involving side panels, it is apparent that the post may be used in roof and floor panels or any other place where posts are used.

Claims (12)

1. An article made by a pultrusion process comprising a reinforced resin body, and a metal piece directly secured to said resin body during said pultrusion process.

2. An article according to claim 1 wherein the metal piece is a metal strip.

3. An article according to claim 1 or 2 wherein the metal piece is partially embedded in the reinforced resin body.

4. An article made by a pultrusion process wherein said process includes the steps of forming and curing and said metal step is added to said reinforced resin body prior to said step of curing.

5. An article according to any preceding claim which comprises a post for supporting panels of a shell structure.

6. A post according to claim 5 which comprises a "Z"-section member with said metal piece on a leg thereof.

7. A post according to claim 6 in contact with a panel and receiving a fastener therethrough to secure the post to the panel.

8. A post according to claim 7 wherein the fastener comprises an upset type rivet in physical contact with the metal piece.

9. An article according to claim 1 substantially as hereinbefore described with reference to the accompanying drawings.

10. A pultrusion method for forming a fibrereinforced resin article in which a metal piece is applied to a face of the formed pultrusion before curing of the resin so as to become secured as part of the cured product.

11. A method according to claim 10 wherein the metal piece is partially embedded in the pultrusion.

12. A pultrusion method substantially as hereinbefore described with reference to the accompanying drawings.