Apparatus for laying a matt of fibrous material

Abstract: Apparatus (17) for laying a matt of fibrous material comprising an upwardly inclined belt (22) onto which the fibrous material is adapted to be fed, one or more combing rollers (23, 24) located above the belt, and a stripping roller (25) at the upper end of the belt for removing the material from the belt and passing into means for laying a matt of the said material.

Description: This invention is concerned with apparatus for laying a matt of fibrous material. It is known from FR-A-2 080 239 an apparatus for laying a matt of fibrous material comprising an upwardly inclined belt onto which the fibrous material is adapted to be fed, a combing roller located above the belt and a stripping roller at the upper end of the belt for removing the material from the belt and passing into means for laying a matt of fibrous material. It is also known from this specification that the material is passed from the stripping roller to a chute and thence to a movable caul as well as disclosing means for weighing the amount of material on the movable caul. According to the present invention apparatus of this kind is characterised in that an adjustable flap 34 is provided at each side of the matt which respectively deflect a small amount of material away from the edges of the matt to form a ridge at the longitudinal portions of the matt. This compensates for the effects of material moving out from the edges of the matt when in the press and allows uniform density to be achieved much closer to the edge of the board than has hitherto taken place. Preferably the material is fed to the inclined belt from a horizontal belt and the material is conveniently fed through rollers 36, 37 and 38 arranged as a barrier to ensure an even feed rate. Moreover two combing rollers 23 and 24 are provided in series. The angle of inclination of the belt and the position of the first combing roller is located so that the material can build up behind it to reach its critical angle of repose and then slide back down rearwardly thereof. A photoelectric cell 21, 35 may be adapted to provide a light beam behind the first combing roller interuption of which is arranged to stop the horizontal belt 20 and hence the feed of further material to stop the horizontal belt 20 and hence the feed of further material to the inclined belt. The second combing roller may be located upstream of the first combing roller and serves to comb the material to a constant depth. In one preferred embodiment the caul may be movable in opposite directions so that a matt can be layed in two passes to give a double thickness. In any case end plates may be provided on the caul to assist in catering for end effects. The invention may be performed in various ways and one specific embodiment will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 - is a general view of apparatus of which the present invention forms a part, and Figure 2 - is a perspective view of apparatus according to the present invention. Figure 1 shows the layout of a machine for making boards from straw and other raw fibrous materials and of which apparatus according to the present invention forms a part as will be more fully explained. In the machine straw is supplied to a straw chopper (not shown) from whence it is fed to a bulk hopper 10a, an elevator 10b, a bulk weighing hopper 10c and a resinating chamber 11 in which a resin bonding agent is mixed in with the straw. Experiments have shown that an ideal mixture is 95% - 97% straw and 3% - 5% bonding agent. It has moreover been found that a particularly suitable bonding agent is methyl di-isocyanate. The straw and resin mix then passes into a matt (matress) laying apparatus 12 which will be described in more detail below after which the laid matts are fed via cauls 13 which feed the matt into a press indicated at 15 which is described in more detail in the present Applicants co-pending Application No. 88 311 748.3. After leaving the press the finished matts are transported on the cauls to a removal station 16 where they are removed prior to trimming where they are removed, sawn to size and stacked. As mentioned above the present Application is concerned with the apparatus for laying the matt and which will now be described more fully with reference to Figure 2. In Figure 2 there is shown in more detail the right hand end of the matt laying apparatus indicated generally at 17 in Figure 1. The resinated straw is passed onto a continuous belt 20, the right hand end of which is shown in Figure 2 by opening doors in the base of the resinating chamber 11. The drive to the belt 20 is controlled by a photo electric cell emitting a beam 19, the belt moving when the beam is unbroken and stopping when the beam is broken. Further photo electric cells 21 and 35 give overriding control to prevent excess resinated material being fed onto the belt 20 and to prevent matt laying if there is insufficient material available. The straw passes from the horizontal belt 20 via distributing rollers 36, 37 and 38 onto an upwardly inclined belt 22 which is only driven when it is required to lay a matt and is switched on and off in sequence with the caul track which is chain driven. When the belt 22 is operating it moves in the direction of the arrow and the straw meets the action of first and second combing rollers 23 and 24 which both rotate in a clockwise direction as shown as by their respective arrows and drive excess material back. These rollers continue to rotate when the inclined belt 22 is stationary. The angle of the inclined belt and the positioning of the rollers 23 and 24 are chosen so that the material which builds up behind the first roller 23 must be able to build up to reach its critical angle of repose and slide back down towards the light beam. The second roller 24 combs the material to a constant depth so that at constant speed of the inclined belt 22 a constant volume of material is carried up the belt to a stripping roller 25 which ensures that the material is pulled off the belt in a uniform stream. The first combing roller 23 has a series of angle irons which form the "teeth" whilst those on the second combing roller 24 are much finer and are formed by a series of spikes, the teeth on the stripping roller 25 also being spikes but being much more numerous and finer still. The material leaving the stripping roller 25 falls into a vertical chute 26 and thence onto an inclined deflector plate 27 and is pulled through by a rotating brush 28 which rotates anti-clockwise in the direction of the arrow. The deflector plate is movable from the position shown by means of a mechanism 30 into a position where the straw passes under a similar roller 31 which also rotates in the direction of its arrow and in the opposite direction to the roller 28. In the position shown in Figure 2 the matt is laid with the caul moving from left to right. For thick boards it is preferable to lay the matt in two passes. This helps to cancel out end effects and also gives a chevron effect to the strata of laid material preventing end loadings of the platens during pressing in the press 15. To make this second pass the deflector plate 27 is moved into its other position by the mechanism 30 and the caul is then moved back again from right to left with the rotating brush 31 pulling the material off the deflector plate 27. The caul onto which the matt is laid is mounted on a weighing mechanism which measures the amount of material laid. The weight of the matt laid is adjustable by altering the speed of the inclined belt 22 thus permitting more or less material to be passed by the stripping roller 25 into the chute 26. A screen 32 is provided to prevent material thrown off the first combing roller 23 from interfering with the light beam 19. The ends of the matt are formed by end plates 33 and end effects are catered for by firstly selecting a correct end plate height, secondly selecting a slowing down of the caul travel speed towards the end of the laying of the matt and also taking into account whether single or double pass laying is being used. A further control of matt thickness along the edges of the matt is obtained by adjustable flaps 34. These deflect a small amount of material away from the edges of the matt throwing up a slight ridge further into the matt. This compensates for the effect of material moving out from the edges of the matt when in the press and allows uniform density to be achieved much closer to the edge of the board than would otherwise occur.

Claims: Apparatus for laying a matt of fibrous material comprising an upwardly inclined belt 22 on to which the fibrous material is adapted to be fed, one or more combing rollers 23, 24 located above the belt and a stripping roller 25 at the upper end of the belt 22 for removing the material from the belt 22 and passing it into means for laying a matt of the said material, the speed of the inclined belt 22 being adjustable to determine the amount of material leaving it and hence the thickness of the matt, the material passing from the stripping roller 25 to a chute 26 and thence to a movable caul and means for weighing the material on the caul characterised in that an adjustable flap 34 is provided at each side of the matt which respectively deflect a small amount of material away from the edges of the matt to form a ridge at the longitudinal edge portions of the matt. Apparatus as claimed in Claim 1, characterised in that the material is fed to the inclined belt from a horizontal belt 20. Apparatus as claimed in Claim 2 or Claim 2, characterised in that the material is fed through rollers 36, 37 and 38 arranged as a barrier to ensure an even feed rate. Apparatus as claimed in Claim 1, Claim 2 or Claim 3, characterised in that two combing rollers 23 and 24 are provided in series. Apparatus as claimed in any one of Claims 1 to 4, characterised in that the angle of inclination of the belt 22 and the position of the first combing roller 23 is located so that the material can build up behind it to reach its critical angle of repose and then slide back down rearwardly thereof. Apparatus as claimed in Claim 5, characterised in that a photoelectric cell 21, 35 is adapted to provide a light beam behind the first combing roller interuption of which is arranged to stop the horizontal belt 20 and hence the feed of further material to the inclined belt. Apparatus as claimed in any one of the preceding Claims, characterised in that in which the second combing roller 24 is located upstream of the first combing roller 23 and serves to comb the material to a constant depth. Apparatus as claimed in any one of the preceding Claims, characterised in that the caul is movable in opposite directions so that a matt can be layed in two passes to give a double thickness. Apparatus as claimed in any one of the preceding Claims, characterised in that end plates 33 are provided on the caul to assist in catering for end effects.

Inventors: BARNES MICHAEL COSMO, BARNES, MICHAEL COSMO
Applicants: COMPAK SYST, COMPAK SYSTEMS LIMITED
Application year: 1988
Main classification: B27N3
IPC codes: D04H1, B27N3