APPARATUS AND PROCEDURE FOR THE COATING OF OBJECTS

Abstract: Apparatus for laminating and/or coating objects (1) with a suitable coating material (2), said apparatus comprising a first vacuum press, an element for heating the coating material, an element for generating a negative pressure between the object (1) and the coating material (2), an element for cooling the coating material (2) and the object (1), and a base (3) on which the object is held during coating. The apparatus comprises at least two vacuum presses and an element (4) for connecting the vacuum presses together so that the bases (3) of the presses form a substantially continuous base (3). In the procedure, the object (1) is coated using an apparatus consisting of at least two vacuum presses.

Description: APPARATUS AND PROCEDURE FOR THE COATING OF OBJECTS The present invention relates to an apparatus as defined in the preamble of claim 1 and to a procedure as defined in the preamble of claim 6 for the lamination and/or coating of objects. Finnish patent specification FI 91225 presents a procedure and an apparatus for coating plate-like objects with a plastic film. In the procedure, the plastic film is first warmed and then applied onto an object which has been treated with heat-activated glue. To promote adhesion, a negative pressure is generated between the plastic film and the object. In a practical application, the object is then taken out of the heating and low-pressure chamber and cooled down by blowing air onto the object using a separate fan. The pressure of the air blown onto the object from a distance by a single fan is unevenly distributed, resulting in uneven cooling of the object and the plastic film on it. Especially the edge areas of the object, which are critical in respect of adhesion of the plastic film, are left without special attention, and consequently the plastic film may be inadequately affixed to the object. Another difficulty with the system is that the apparatus has separate parts for affixation and cooling. This limits the maximum size of the object to be coated with the apparatus to the size permitted by its heating part. The object of the present invention is to eliminate the problems described above. A specific object of the present invention is to present a new type of solution for an apparatus that can be used to coat or laminate plate-like or shaped objects of various sizes . As for the features characteristic of the invention, reference is made to the claims. The apparatus of the invention comprises at least two vacuum presses. The vacuum press comprises an element for heating the coating material and an element for generating a negative pressure between the object and a suitable coating material. The object may be of a plate-like shape or it may be a shaped object with a patterned surface, or the object may have e.g. a hemispherical shape. Examples of suitable coating materials are plastic foil, paper, wood veneer, glass fibre, metal and corresponding lamination materials. The vacuum press comprises a base on which the object is held in place during the essential operations in the coating process. These operations are pre-heating, generation of negative pressure, heating and prefera- bly cooling. According to the invention, the vacuum press comprises an element for joining it to a second vacuum press so that the bases of the presses form a substantially continuous base. The joining element may consist of e.g. an adapter fitted between the two presses placed side by side, a screw joint connecting the two presses together, a hook-like gripping or latching device, a staple. The base preferably extends to the edges of the press, so the joining element connecting the bases may be e.g. a tape or a fixed pro- jection comprised in the base and forming a tongue- and-groove type joint with the other base. In a preferred case, a working area is formed on top of the base, so that when the two presses are connected together, the working areas form a continu- ous working area. This makes it possible to coat or laminate objects that are larger than an individual press, the object size being limited by the combined working area. In a preferred embodiment of the invention, the second vacuum press comprises only some of the elements of the first vacuum press, so the second vac- uum press may utilise the functions of the first vacuum press, such as e.g. control functions. In a feasible embodiment, the second vacuum press also utilises the pressure generating elements of the first vacuum press. The vacuum presses may preferably also be completely identical, in which case each one is normally used separately but, when necessary, the presses can be combined to allow coating or lamination of larger objects . The apparatus preferably comprises a flexible membranous foil which is lowered onto the coating material and the object. The membranous foil can preferably be reused several times. In a preferred embodiment of the invention, the apparatus comprises cooling air nozzles from which cool air is supplied over the membranous foil and which are located at the edges of the base. In addition, the cooling air is preferably pressurised. In an embodiment, the nozzles are directed in an oblique downward direction or the nozzles may consist of holes in a frame above the press, the cooling air being discharged from said holes. The cooling of the coating material and the object is done in a controlled manner so that the edges are also taken into account. In an embodiment of the invention, cooling can also be effected without a membranous foil. The apparatus preferably comprises a safety device that prevents the operation of the vacuum press when the safety device has detected an obstruction at the edges of the base. The safety device preferably comprises touch-sensitive, e.g. electrically conductive material to allow detection of an obstruction. The safety device may respond to an obstruction e.g. on the basis of a change in the capacitance or resis- tance of the material. The safety device may prefera- bly also detect an obstruction by an optical method, using e.g. a photosensitive material. In the procedure of the invention, the coating material is placed on top of the object to be coated, a negative pressure is generated between the object and the coating material, the coating material is heated to affix it to the object and the coating material and the object are preferably cooled after affixation. According to the invention, the object is coated/laminated using an apparatus consisting of at least two vacuum presses. As compared with prior art, the invention provides the advantage that the system has a modular construction. An important factor contributing towards implementing a modular construction is the form of the vacuum press, in which the working area extends close to the edges of the press. From two or more vacuum presses, it is possible to set up an assembly whose combined working area allows coating of objects larger than the working area of a single press. At the same time, the manufacturing costs of the apparatus remain low because preferably only one type of press is manufactured. The user can enlarge the apparatus as necessary, so a press once bought continues to be usable. The advantages of the procedure of the invention include a reduced consumption of coating material due to diminished waste. The procedure preferably allows the use of sheets pre-cut to size. A further advantage is that the procedure allows simultaneous coating of several different objects. In the procedure of the invention, if a fault occurs at any point during the coating process, e.g. if the coating material burns through, this will not entail rejection of the entire coating lot. In the following, the invention will be described by the aid of a few examples of its embodiments by referring to the attached drawing, wherein Fig. 1 presents an apparatus according to the invention; and Fig. 2 illustrates a combination of a number of vacuum presses in top view. Fig. 1 depicts an apparatus according to the invention for the coating of plate-like objects 1. Fig. 1 shows two vacuum presses connected together and an element 4 for joining the bases of the presses. When joined together, the bases form a continuous base. In this example, the frame above the press has been replaced with a frame 9 larger than the frame of the first press, covering both presses. The working areas on top of the bases are combined, thus making it possible to coat objects larger than a single working area. The object 1, coating material 2 and raising block 7 shown in Fig. 1 are in the working area of both presses. The use of a raising block 7 makes it possible to coat e.g. the edges of the plate at the same time. The membranous foil 5 in the example illustrated is attached to the edges of the combined working area, to the frame 9 above the presses. The cool- ing nozzles 6, directed in an obliquely downward direction, are located in the frame 9 above each press. Placed at the edges of the base is a safety device 8, which interrupts the operation of the apparatus if it detects an obstruction at the edges of the base or the working area. Fig. 2 shows a top view of a number of vacuum presses joined together. In the apparatus of the invention, the working area extends close to the edges of the working area. Therefore, the presses can be joined by any one of their edges. In this example, the control functions of all the presses 20, 21 are con- trolled via the control panel of press 20. Presses 21 can be chained one after the other as slaves so that all control functions are implemented in the master press 20. All the presses are substantially equally effective, for they all have the elements essential for the coating of an object. Thus, in principle there is no limit to the maximum size of the apparatus. A base 3 as provided by the invention may consist of one or more vacuum press bases. On top of the base a working area is formed, where all the essential operations in the coating process are performed. The object 1 is held in place throughout the coating process. Arranged around the object 1 is a frame 7, upon which the coating material 2 is placed. Several ob- jects may be placed on the base 3 for simultaneous coating. During the arrangements preceding the actual coating operation, the membranous foil 5 is in the raised position, so the working area is open. During this time the membranous foil is being heated by heat- ing elements placed above it, so the membranous foil is warm when it is lowered, thus accelerating the affixation of the coating. The membranous foil 5 is lowered and a negative pressure is generated under the membranous foil 5. This also produces a negative pressure between the object 1 and the coating material 2, so they are pressed together. The affixation of the coat onto the object 1 can be promoted by applying glue to the object or to the coating material 2. The membranous foil 5 is heated, and the heat also propagates into the coating material 2 and into the object 1. The membranous foil 5 compensates local temperature differences and protects the coating material against burn- through. The coating material 2 is affixed to the ob- ject 1. The object 1 and the coating material 2 are cooled by blowing cool pressurised air over the membranous foil 5. The air nozzles 6 blow air from ' the edges of the base, from the frame above the base. At the same time, a negative pressure is still maintained in the space under the membranous foil 5. By this method, the coated object is cooled in a controlled manner and especially the critical edge areas are more successfully coated. After the object has cooled down, the membranous foil 5 is raised again. The same membranous foil 5 can be used in several successive coating operations. The invention is not restricted to the examples of its embodiments described above, but many variations are possible within the scope of the inventive idea defined by the claims.

Claims: CLAIMS 1. Apparatus for laminating and/or coating objects (1) with a suitable coating material (2) , said apparatus comprising - a first vacuum press, which comprises an element for heating the coating material, an element for generating a negative pressure between the object and the coating material, and a base (3), on top of which the object is held during coating, characterised in that the apparatus comprises at least two vacuum presses and an element (4) for connecting the vacuum presses together so that the bases (3) of the presses form a substantially continuous base (3) . 2. Apparatus as defined in claim 1, characterised in that a working area is formed above each base (3) and that, when the vacuum presses are joined together, the working areas form a continuous working area. 3. Apparatus as defined in claim 1 or 2, characterised in that the apparatus comprises a flexible membranous foil (5), which is lowered onto the coating material (2) and the object (1) . 4. Apparatus as defined in any one of claims 1 - 3, ch a r a c t e r i s e d in that the apparatus comprises cooling air nozzles, from which cool air is supplied over the membranous foil (5) and which are located at the edges of the base (3) . 5. Apparatus as defined in any one of claims 1 - 4, characteri sed in that the apparatus comprises a safety device (8) that prevents operation of the vacuum press when the safety device (8) has detected an obstruction at the edges of the base (3) . β. Procedure for the lamination and/or coating of objects (1) with a suitable coating material (2), in which procedure - the coating material (2) is placed onto the object (1) to be coated, - a negative pressure is generated between the object and the coating material, and - the coating material is heated to affix it to the object, characterised in that the object (1) is coated using an apparatus consisting of at least two vacuum presses.

Inventors: RAUMAVIRTA SAULI, RAUMAVIRTA, SAULI
Applicants: DIAPEK OY, RAUMAVIRTA SAULI, RAUMAVIRTA, SAULI
Application year: 1998
Main classification: B32B31
IPC codes: B29C63, B32B37