EP0041482A1

EP0041482A1 - Equipment to spread glues or paints on continuously feeded sheet materials

Info

Publication number: EP0041482A1
Application number: EP81830070A
Authority: EP
Inventors: Guido Grisenti
Original assignee: TABU SpA
Current assignee: TABU SpA
Priority date: 1980-05-30
Filing date: 1981-05-08
Publication date: 1981-12-09
Also published as: ES258699U; ES258699Y; IT8021938V0

Abstract

An equipment to spread glues or paints on continuously feeded sheet materials of the kind comprising a plurality of spray guns (17) disposed at a predetermined distance one from the other on a bearing rod (18) mounted on the casing (11), a box-type body, made of transparent material, wrapping up said casing and defining a spraying chamber, and at least one pair of proximity switches disposed in connection with the spraying area for the automatic control of said spray guns (17) when the sheet is introduced in the spraying area, said sheet feeding assembly consisting of a roller disposed at right angles to the material feeding direction and cooperating with an overhanging shaft on which a plurality of bearings are loosely mounted.

Description

This invention relates to an equipment to spread glues or paints on continuously feeded sheet materials of the kind comprising a sheet feeding assembly mounted on a bedplate, a glue or paint distributor mounted on a casing fixed on the bedplate perpendicularly to the sheet feeding direction, a vessel to collect the glue or paint in excess, cyclically connected to the distributor and a transfer unit to transfer the sheets from the feeding area to an area of stacking. This equipment is particularly used to spread glues by high pressure spraying on surfaces of any size and of little thicknesses.
It is known that in the wood industry and particularly in the plywood industry and in the one for the manufacture of precomposed sheets (by precomposed sheets we mean a material cut from a block composed of many thin sheets of wood glued together), it is of the greatest importance to distribute and to spread the coat of glue uniformly on the sheets.
At present the best known glue-spreading machines are of the kind provided with cylinders, including, according to the cases, two or four steel cylinders covered with rubber. The cylinders are disposed parallelly one over the other and the sheet of material to be glued is passed therethrough, the dosage of the glue being possible owing to the presence of a plurality of grooves having different sections obtained either parallelly or helically on the cylinder covering.
However, the glue-spreading machines of the kind specified suffer from a number of drawbacks which do not allow a suitable use of the same glue-spreading machines on all types of surfaces. By way of example, it is to be noticed that, when the glue has to be spread on the surface of a sheet having a brittle and corrugated woody structure and of little thickness, in the range of tenths of millimetre or of millimetres, there is the risk to cause irreparable breaks on the sheet or even to destroy it completely.
A further disadvantage of the machines of the kind specified is that the cylinders covered with rubber and grooved are easily subject to wear particularly when the materials to be worked have been cut with uneven thicknesses. In fact, the difference in thickness causes the cylinders to be subjected to different stresses and therefore to wear.
A yet further disadvantage residing in the glue-spreading machines of the kind provided with cylinders is that the cylinders, as they are subject to bending stresses, practically set a limit to the cross sizes of the same machines. Consequently, such limits have repercussions on the sizes of the sheets to be glued which cannot, therefore, exceed a predetermined width.
These disadvantages have been partially eliminated by a machine to spread glues, paints and the like including a glue distributor loca1 ed transversally to the sheet feeding direction which allows the glue to be delivered in parallel thin threads, said distributor consisting of a vessel provided on its bottom with a plurality of holes having a predetermined diameter. This machine however, notwithstanding its sure technical and functional advantages, has some drawbacks too; in particular the glue spreading is not satisfactory and the distribution of the same is not uniform.
The main object of this invention is to eliminate all the drawbacks specified above, carrying out an equipment to spread glues or paints which is suitable to distribute both glues and paints in a perfect manner even on no perfectly flat surfaces, of large sizes and little thicknesses.
This and other objects and advantages of the present invention, which will become more evident from the description which follows, are achieved by an equipment to spread glues or paints on continuously feeded sheet materials which is characterized in that it comprises a plurality of spray guns disposed at a predetermined distance one from the other on a bearing rod mounted on the casing, a box-type body, made of transparent material, wrapping up said casing and defining a spraying chamber and at least one pair of proximity switches, connected to the spraying area for the automatic control of said spray guns when the sheet is introduced in the spraying area, the sheet feeding assembly consisting of a roller disposed perpendicular ly to the material feeding direction and cooperating with an overhanging shaft on which a plurality of bearings are loosely mounted.
Advantageously said spray guns are provided with a stop nut, the unloosing of the latter allowing their shifting in the horizontal direction.
Advantageously and according to a further feature of the invention, said rod bearing the guns can be shifted vertically by means of lead screws disposed on the casing in connection with the ends of the same rod.
Further features and advantages of the invention will become more evident from the detailed description of a preferred embodiment of an equipment to spread glues or paints on sheet materials, given here inafter, by way of example only, with reference to the accompanying drawings, in which:

- Figure 1 is a diagrammatic side elevation view of the equipment according to the invention;
- Figure 2 is a diagrammatic sectional view along the line II-II in Figure 1;
- Figure 3 is a diagrammatic view of the glue or paint feeding system.

Referring to these Figures and particularly to the first one, it has been indicated at 1, as a whole, an equipment for the spreading of glues or paints by high pressure spraying on sheet materials 2 continuously feeded from a drawing area 3 to a stacking area 4.
The equipment 1 consists essentially of a bedplate 5 on which a sheet feeding assembly indicated as a whole at 6 is mounted. It comprises a roller 7 disposed at right angles to the feeding direction of the sheets 2 and an overhanging shaft 8 on which a plurality of bearings 9 are loosely mounted, the bearings 9 having an inner diameter rather bigger than the diameter of the shaft 8; by this way the bearings 9 can assure a friction which is suitable to allow the feeding of the sheets 2 to be glued or painted without giving rise to an excessive pressure on the same, which could cause their break.
Referring particularly to Figures 1 and 2, it has been indicated at 10, as a whole, some glue or paint distributors which are mounted on a casing 11 fixed on the bedplate 5, their arrangement being at right angles to the feeding direction of the sheets 2. Under the distributors 10 there are corresponding vessels 12 which are suitable to collect the glue or paint in excess and to recycle it according to modalities which will be more clearly explained afterwards.
Moreover, a sheet transferring unit, indicated as a whole at 13, is mounted on the bedplate 5. It allows the glued or painted sheets to be transferred to the stacking area 4 or, in any way, to an area of use. This transferring unit consists of a plurality of lower rollers 14 and of a plurality of upper rollers 15 disposed at right angles to the feeding direction of the material. According to one of the features of this invention, the surfaces of the upper rollers 15 are provided with a plurality of catching needles 16 disposes radially to allow a good catching on the surfaces of the sheets 2 subject to gluing or painting and to prevent these surfaces from being soiled, dirtied or damaged during the transport.
Referring particularly to Figure 2 of the drawings, the distributor 10 consists of a plurality of spray guns 17 which are mounted at a predetermined distance one after the other, on a bearing rod 18 provided, at its ends, with lead screws 19 and 20 engaged in an operative manner with threaded rods 21 and 22 integral to the casing 11 and operable by means of a handwheel 23. Acting on the handwheel 23 it is possible to act on a mechanical device 24 of the kind worm screw - gear wheels in order to get the parallel rising or lowering of the lead screws 19 and 20 of the bearing rod 18, which allows the adjustment of the width of the spraying sector provided by the guns 17. It is to be noted that these guns are provided with a stop nut 25 (Figure 1) the unloosing of which allows them to be shifted horizontally as shown by the arrows 26 in Figure 2.
The delivery of glue or paint by the guns 17 takes place automatically, as the sheets 2 to be treated come near the spraying area. For that purpose, in this area there is provided the presence of at least one pair of proximity switches 27 rigidly mounted on the bedplate 5.
According to a further feature of the invention, each glue distribu tor 10 is provided with a bqx-type body 28, preferably made of transparent material, which wraps up the whole casing 11 defining a spraying chamber 29. The box-type body 28 is provided to prevent the sprayed material, above all glue, from settling on the environment surrounding the operating area, so that not only the equipment devices, but also the area of passage for the operators could be soiled. On the contrary, in this case the glue settles on the walls of the box-type body 28 and can then drip down till to reach the collecting vessels 12 where a canalization 30 provides for its recycling.
Finally, for the purpose of preventing the sheets 2 from being dangerously bent as they pass on the collecting vessels 12, grates 32 are provided between the same vessels and the overhanging casings 11. These grates prevent the sheets from being bent while allowing the glue or paint in excess to regularly flow into the collecting vessels 12.
Referring now particularly to Figure 3 of the drawings, the glue feed ing system includes a tank 31 suitable to mix the glue together with hardening agents and other additives fitted for the purpose, or to contain the paint to be sprayed on sheets 2. The tank 31 communicates, through a duct 33, with a high pressure pump 34, a heater unit 35 being inserted therebetween, if necessary. A further duct 36 communicates the pump 34 with the automatic spray guns 17. As can be seen in Figure 3, a plenum chamber 37 and a filter 38 are inserted on the duct 36. In the same Figure a manually operable spray gun controlled by the opening of a valve 40 has been indicated at 39. The plenum chamber 37 acts as a regulator of the glue flow sent in a pulsating way from the pump 34 to the guns 17 and 39.
From what above it becomes evident that the main advantage of the equipment according to the present invention consists of the possibility to obtain a perfectly uniform spreading of the glue on the sheets 2 without causing any damage to these ones. Furthermore, the above equipment is provided with a very wide range of adjustments as to the quantity of glue or paint to be delivered. In fact, these adjustments can be obtained not only by means of the normal media connected to the spray guns (opening or closing of the delivery nozzles or replacement of the same), but also either by modifying the feeding speed of sheets 2, or by raising or lowering the bearing rod 18 supporting the spray guns 17, on the same sheets. Practically, by raising the guns 17 there is a widening of the spraying sector and consequently a widening of the sheet surface sprayed with glue or paint.
Obviously, it will be understood by those skilled in the art that, al though a preferred embodiment has been shown and described, the invention is not limited thereto or thereby and modifications can be carried out within the scope of the claims. Particularly, when paints, glues or mixtures having more components are used, it is possible to provide two or more equipments supplying them, these equipments work ing in sequence and independently from one another, or working in parallel, according to the different requirements.

Claims

1) An equipment to spread glues or paints on continuously feeded sheet materials of the kind including a sheet feeding assembly mounted on a bedplate perpendicularly to the sheet feeding direction, a vessel to collect the glue or paint in excess, cyclically connected to the distributor and a transfer unit to transfer the sheets from the feeding area to an area of stacking, characterized in that it comprises a plurality of spray guns disposed at a predetermined distance one from the other on a bearing rod mounted on the casing, a box-type body, made of transparent material, wrapping up said casing and defining a spraying chamber, and at least one pair of proximity switches disposed in connection with the spraying area for the automatic control of said spray guns when the sheet is intro duced in the spraying area, said sheet feeding assembly consisting of a roller disposed at right angles to the material feeding direction and cooperating with an overhanging shaft on which a plurality of bearings are loosely mounted.

2) An equipment according to claim 1, characterized in that said rod bearing the guns can be shifted vertically by means of lead screws mounted on the casing in connection with the ends of the same rod.

3) An equipment according to claim 1, characterized in that said transferring unit consists of a plurality of rollers laying one upon the other two by two and disposed at right angles to the material feeding direction, the upper rollers, along their whole development, being provided with a plurality of radial catching needles.