MANUFACTURING ARRANGEMENT

This invention relates to a manufacturing arrangement, and in particular to an arrangement in which recycled fibrous materials can be incorporated into a sheet material.

A number of techniques are known in which sheets of suitable materials known as sheet molding compounds or composites (SMCs) are molded to take predetermined shapes.

Techniques of this type are in widespread use in, for example, the manufacture of vehicle body parts. The SMC materials used typically comprising a thermoset resin incorporating glass or other suitable material reinforcing fibres. The fibres used in such materials are often relatively long, for example a few centimetres long, as the use of relatively long fibres enhances the strength of the material.

A typical manufacturing technique used in the production of an SMC material comprises passing a lower carrier film through a doctor box to apply a uniform thickness layer of a resin material incorporating filler materials, etc, thereto. The lower carrier film with the layer of resin material applied thereto then passes through a station in which virgin glass fibres are cut from a roll or rolls and are sprinkled onto the resin material. After application of the glass fibres, an upper, resin material covered carrier film is introduced over the lower carrier film, resin material and glass fibres, and the upper and lower carrier films are pressed or compacted together. The completed SMC material is then stored ready for subsequent use in a molding operation.

The molding techniques in which the SMC material is used tend to produce significant quantities of waste, for example in the form of off-cuts. It is desired to be able to make use of at least some of the materials that would otherwise go to waste.

According to one aspect of the invention there is provided a method of manufacturing an SMC material comprising the steps of:

(a) applying a resin material to a first carrier film;

(b) sprinkling recycled material fibres onto the resin material and first carrier ¹ film;

(c) sprinkling virgin material fibres onto the resin material and first carrier film; and

(d) sandwiching together the first carrier film and a second carrier film with the virgin and recycled material fibres located therebetween.

The steps do not necessarily have to be undertaken in the order set out above. For example, the order in which the virgin and recycled material fibres are introduced may ' be swapped, or it may even be possible to introduce them simultaneously.

The method of the invention has the advantage that recycled material fibres, obtained for example by grinding of waste SMC material can be reused in the manufacture of fresh SMC material.

Preferably, the step of sprinkling recycled material fibres includes a step of moving fibres from a hopper to a distributor using a feed system. The distributor preferably

comprises a sieve and drive means operable to cause the sieve to shake or vibrate. The feed system is preferably controllable to control the rate at which fibres are moved to the distributor. Conveniently, the feed system comprises at least one rotatable component rotatable to move fibres from the hopper to the distributor, and drive means operable to drive the rotatable component at a speed to achieve a desired fibre delivery rate to the distributor.

The rotatable component may comprise, for example, a shaft carrying a plurality of brushes, the brushes being spaced apart to define a plurality of chambers. In use, those ones of the chambers open to the hopper will tend to fill with fibres. Rotation of the shaft results in the full chambers no longer being open to the hopper, and instead in those chambers opening over the distributor whereon the fibres will fall into the distributor under the action of gravity. The use of brushes is advantageous in that damage to the fibres, for example breaking thereof, is reduced.

Alternatively, the rotatable component may comprise a pair of oppositely rotating rollers arranged to deliver fibres therebetween upon rotation thereof.

The distributor may distribute the recycled fibres directly onto the resin and first carrier film. Alternatively, it may distribute the fibres onto a conveyor belt operable to deliver the fibres to the resin and first carrier film. By controlling the speed of operation of the conveyor, in conjunction with control over the speed of operation of the feed system, it will be appreciated that the rate of fibre delivery to the resin and first carrier can be controlled.

The invention further relates to a delivery apparatus comprising a hopper, a distributor and a feed system operable to move fibrous material from the hopper to the distributor. The distributor preferably comprises a sieve and drive means operable to cause the sieve to vibrate. The feed system is preferably controllable to control the rate at which fibres are moved to the distributor. Conveniently, the feed system comprises at least one rotatable component rotatable to move fibres from the hopper to the distributor, and drive means operable to drive the rotatable component at a speed to achieve a desired fibre delivery rate to the distributor.

The rotatable component may comprise, for example, a shaft carrying a plurality of brushes, the brushes being spaced apart to define a plurality of chambers. In use, those ones of the chambers open to the hopper will tend to fill with fibres. Rotation of the shaft results in the full chambers no longer being open to the hopper, and instead in those chambers opening over the distributor whereon the fibres will fall into the distributor under the action of gravity. The use of brushes is advantageous in that damage to the fibres, for example breaking thereof, is reduced.

Alternatively, the rotatable component may comprise a pair of oppositely rotating rollers arranged to deliver fibres therebetween upon rotation thereof.

The distributor may distribute the recycled fibres onto a conveyor belt. By controlling the speed of operation of the conveyor, in conjunction with control over the speed of

operation of the feed system, it will be appreciated that the rate of fibre delivery can be controlled.

The invention further relates to an SMC material production line comprising means for applying a resin to a first a first carrier film, a delivery apparatus as described hereinbefore and operable to sprinkle recycled material fibres onto the resin material and first carrier film, means for sprinkling virgin material fibres onto the resin material and first carrier film and means for sandwiching together the first carrier film and a second carrier film with the virgin and recycled material fibres located therebetween.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic view of a typical SMC material production line;

Figure 2 is a view of part of an SMC material production line in accordance with one embodiment of the invention;

Figure 3 is a diagrammatic illustration of the delivery apparatus of the production line of Figure 2;

Figures 4 and 5 illustrates part of the apparatus of Figure 3 in greater detail;

Figure 6 is a diagram illustrating operation of part of the apparatus of Figure 3;

Figure 7 illustrates an alternative arrangement; and

Figure 8 illustrates a modification.

Referring to Figure 1, the typical SMC material production line comprises an apparatus 10 including a roll 12 from which a first, lower carrier film 14 is withdrawn. The first carrier film 14 is fed through a first doctor box 16 which contains a paste 18 made up of a resin material and filler components. The first doctor box 16 delivers a uniform thickness layer of paste 18 over the upper surface of the carrier film 14. After having had the paste 18 applied thereto, the first carrier film 14 is fed to a station 20 in which virgin glass fibres 22 are cut or chopped from a roll or rolls of glass filaments, the glass fibres 22 falling onto and being sprinkled over the paste covered surface of the -first carrier film 14.

A second, upper carrier film 26 is withdrawn from a roll 28 and passed through a second doctor box 30 operable to apply a uniform thickness layer of a paste similar to the paste 18 to a surface thereof. The paste covered surface of the second carrier film 26 is laid over the paste and glass fibre covered surface of the first carrier film 14 such that the layers of paste and the glass fibres 22 are sandwiched between the carrier films 14, 26, and the assembly is then passed through a station 32 in which the carrier films 14, 26 are pressed together. The compressed or compacted SMC material so produced is then fed to a storage container 34 for storage until it is required in a subsequent molding operation.

The production line of the present invention differs from the typical production line described hereinbefore by including an additional station in which recycled material fibres are introduced into the SMC material. The recycled material fibres are conveniently formed by grinding of waste SMC material, and so they cannot be introduced using a station similar to that used to deliver virgin fibres.

In accordance with one embodiment of the invention, as shown in Figures 2 to 6, a additional station takes the form of a delivery apparatus 40 located so as to deliver recycled material fibres to the paste covered surface of the first carrier film 14 at a position between the first doctor box 16 and the station 20. The delivery apparatus 40 comprises a storage hopper 42 arranged to hold a quantity of recycled material fibres. Beneath the hopper 42 is a feed system 44 operable to feed fibres from the hopper 42 to a distributor 46 at a controllable speed.

The feed system 44 comprises a housing 48 defining an elongate opening 50 which opens into the bottom of the hopper 42. Located within the opening 50, and extending along the length thereof, is a shaft 52 which is supported for rotation by appropriate bearings (not shown). The shaft 52 carries four equiangularly spaced brushes 54, the brushes 54 being of sufficient bristle length that the ends of the bristles bear against the housing 48. The opening 50 provided in the housing 48 is designed such that the shaft 52 and brushes 54 serve to close the opening 50 irrespective of the angular position of the shaft 52.

A motor 56 and associated drive transmission in the form of a belt 58 is provided to drive the shaft 52 for rotation. The speed of rotation of the motor 56, and hence the speed of rotation of the shaft 52 can be controlled.

As best seen in Figure 6, the shaft 52 and brushes 54 serve to define four chambers 60a, 60b, 60c, 6Od. With the shaft 52 in the orientation illustrated it will be appreciated that the chambers 60a and 60b are open to the hopper 42, thus fibres from the hopper 42 will tend to fall into the chambers 60a, 60b. Rotation of the shaft 52 in the direction of arrow 62 will cause brush 54 to gently draw additional fibres into the chamber 60a. As the rotation continues, a point will be reached at which the chamber 60a no longer opens into the hopper 42, and subsequently the chamber 60a will open to the lower side of the feed system 44, whereon the fibres within the chamber 60a will tend to fall therefrom under the action of gravity to the distributor 46. By this time, the chamber 60c will be open to the hopper 42, and hence will be ready to start filling with fibres.

The fibres falling from the feed system 44 enter a second hopper 66 forming part of the distributor 46. The second hopper 66 has an opening at its bottom across which extends a mesh or sieve screen 68. The second hopper 66 and screen 68 are supported upon resilient feet 70, for example in the form of rubber springs or dampers, and a motor 72 is provided and operable to cause the screen 68 to vibrate. Vibration or shaking of the screen 68 eases the passage of fibres through the screen 68, evenly distributing the fibres and breaking up relatively large bundles of fibres.

Although in some applications it may be possible to arrange for the vibrating screen 68 to deliver or sprinkle the fibres directly onto the paste covered surface of the first carrier film 14, in the arrangement illustrated the fibres are delivered to a conveyor 74 which transports the fibres to the location at which they are to be sprinkled onto or over the first carrier film 14 where they fall from the conveyor 74 onto the carrier film 14.

It will be appreciated that, in accordance with the invention, recycled material fibres are introduced into the SMC material during the manufacture thereof, thereby permitting recycling of at least part of waste SMC material.

A number of modifications and alterations may be made to the arrangement described hereinbefore. For example, the hopper 48 is illustrated as being of tapering form with both sides thereof inclined. However, arrangements may be possible in which one of the walls of the hopper 48 is arranged vertically. The hopper 66 may be similarly modified. The feed system 44, instead of comprising a shaft 52 with four brushes 54 formed thereon, may include fewer or more brushes. Alternatively, it may be replaced with a different rotatable component, for example a roller operable to draw recycled fibre material from the hopper. It may be desirable for such a roller to have a surface texture, rather than be of smooth form, to assist in drawings fibres from the hopper. Figure 7 illustrates an arrangement in which a pair of contra-rotating rollers 16 are provided in the opening 50 to transfer fibre material from the hopper 48 to the distributor 46. Although such a feed system may operate adequately, it will be appreciated that the opening 50 is not completely closed in such an arrangement and so there is some risk of materials falling from the hopper 48 at an uncontrolled rate. With

some materials, for example relatively long fibres, such uncontrolled passage of material is likely to be at only a very low level, and so may be acceptable. However this may not always be the case.

As illustrated in Figure 8, in order to further enhance or improve the distribution of recycled fibres in the final product, a flail device 80 may be used. In the arrangement illustrated, the flail device 80 is located beneath the distributor 46, but it will be appreciated that other arrangements are possible, for example the flail device 80 may be incorporated into or replace a distributor in some arrangements.

The flail device 80 comprises a rotatable, motor driven shaft 82 provided with a number of radially outwardly projecting pins 84. Conveniently the pins 84 are of metallic form but this need not always be the case. A guard or deflector 86 is provided beneath the distributor 46 and above the flail device 80 to direct fibres delivered from the distributor 46 towards the part of the flail device 80 in which the pins 84 are moving in a downward direction, in use. The shaft 82 is driven for rotation at high speed, and the interaction between the pins 84 and the falling fibres is such that clumps or bundles of fibres will tend to be further broken up, resulting in the production of a more even, random distribution of the recycled fibres in the final product. It will be appreciated that the provision of the deflector 86 tends to prevent fibres from being thrown upwards by the operation of the flail device 80.

A second guard or deflector 88 is positioned close to the outer ends of the pins 82 and serves to ensure that substantially all of the fibres interact with the pins 82 of the flail device 80, in use.

A number of other modifications and alterations are also possible without departing from the scope of the invention.