Abstract:
A method of manufacturing painted profiles from metallic strips and a corresponding machine. The method includes the following stages: a) providing a spool with a first material; b) providing a spool with a second material; c) making the first and second materials pass through together in such a way that the coat of primer of the first material and the coat of paint of the second material are juxtaposed and in mutual contact, while the assembly of materials undergoes heat and pressure; d) optionally, detaching and eliminating the film from the assembly of materials; e) shaping the assembly of materials continuously, keeping the assembly of materials, possibly without the film, at a temperature that is essentially the same as that applied in stage c) until stage e) is completed. The machine includes means for carrying out said method. Applicable to painting metallic strips by transfer, before continuous shaping.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention refers to a method of manufacturing painted profiles from metallic strips and to the corresponding machine.  
           [0003]    2. Description of Related Art  
           [0004]    Continuous painting by transfer of determinate products with an appreciably constant cross-section and great length, with a view to decorating them, is known. Also known is the execution of such continuous painting by pressure and heating, using a transfer material which includes a coat of paint supported and protected on its obverse side by a sheet of synthetic resin or film. Said material is applied with the reverse of the coat of the paint on the surface of the product to be painted, while both are passing through an application position in which the reverse of the coat of paint of the material is placed into direct contact with the surface of the product to be painted. The passage of the assembly between heating and pressure rollers determines that the coat of paint tends to be transferred from the film to the surface of the product to be painted. The film can separate from the anverse of the coat of paint and, therefore, from the assembly, in a later stage, leaving the product permanently painted by said coat of paint.  
           [0005]    It should be pointed out that the transfer material (coat of paint+film) is a very specialised product in the market, which is presented in spools. The manufacturer of the final painted products usually acquires the transfer material from the few companies capable of producing it. Spools of transfer painting material may be obtained, for example, from Leonhard Kurz GmbH &amp; Co, Fürth, Germany, with catalogue reference, Touchwood® SO-SR.  
           [0006]    The art indicated above is applied successfully to products which are painted when they have already substantially received their final form, in cross-section, such as finished or almost finished profiles, strips or boards made of wood, shavings, fiber conglomerates, etc., or such as profiles made of synthetic resin, such as PVC or the like.  
           [0007]    On the other hand, said art does not produce painted products of high quality in the case of strips or metallic profiles which, after applying the coat of paint, must be considerably distorted or folded to carry out continuous shaping which gives them the desired final cross-section. This happens, for example, in manufacturing using a strip of aluminium or its alloys, slats or other profiles for false ceilings or ceiling roses. In these cases, the metal of the strip has little adherence with respect to the paint which is transferred to it and, also, distortion of the strip once it is painted, during the continuous shaping, causes cracks in the coat of paint, especially in the fold areas, such as the edges of the slats, producing finished products which do not have a sufficient quality of painting.  
         SUMMARY OF THE INVENTION  
         [0008]    The inventor of the present invention set himself the task of providing a method and a machine by means of which, using transfer material of the type indicated above, metallic strips or profiles could be painted which, after applying the coat of paint, must undergo considerable distortion during a continuous shaping operation to obtain the desired final cross-section.  
           [0009]    To do this, the invention consists of a method for manufacturing painted profiles from metallic strips characterised in that it includes the following stages:  
           [0010]    a) providing a spool with a first material which includes a metallic strip and a primer coat on the side of the strip which must be painted in the finished profile;  
           [0011]    b) providing a spool with a second material which includes a coat of paint, adhering transitorily to a temporary detachable supporting and protective film;  
           [0012]    c) making the first and second materials pass through together, in such a way that the primer coat of the first material and the coat of paint of the second material are juxtaposed and in mutual contact, while the assembly of materials undergoes heat and pressure so that the coat of paint adheres more strongly to the primer coat than to the film;  
           [0013]    d) optionally, detaching and eliminating the film from the assembly of materials;  
           [0014]    e) continuously shaping the assembly of materials, possibly without the film, to obtain the desired finished profile, keeping the assembly of materials, possibly without the film, at a temperature which is essentially the same as that applied in stage c) until stage e) is completed.  
           [0015]    In accordance with an optional characteristic of the invention, before stages a) and b), the corresponding spools undergo stabilising storage.  
           [0016]    In accordance with another optional feature of the invention, before stage c) the temperature of the first material is raised to a value equal to, or higher than, the temperature of stage c).  
           [0017]    In accordance with another optional feature of the invention, after stage e), the continuous profile undergoes a cutting operation into sections of predetermined length.  
           [0018]    In accordance with another optional feature of the invention, after stage e), the continuous profile undergoes a cutting operation into sections of predetermined length and, optionally, a conventional varnishing or lacquering operation.  
           [0019]    In accordance with another aspect of the invention, this includes a machine for carrying out the method of the foregoing paragraphs, characterised in that it includes:  
           [0020]    i) means for making the first and second materials pass through together in such a way that the primer coat of the first material and the coat of paint of the second material are juxtaposed and in mutual contact;  
           [0021]    ii) means for subjecting the assembly of materials to heat and pressure so that the coat of paint adheres more strongly to the primer coat than to the film;  
           [0022]    iii) means for, optionally, detaching and eliminating the film from the assembly of materials;  
           [0023]    iv) means for continuous shaping of the assembly of materials, optionally with or without the film, to obtain the desired final profile; and  
           [0024]    v) means for maintaining the assembly of materials, possibly without the film, at a temperature essentially the same as that applied in stage c), until stage e) is completed.  
           [0025]    According to another optional feature of the invention, before the point of contact between the first material and the second material, the machine includes a preheater of the first material.  
           [0026]    According to another optional feature of the invention, the means (ii) for subjecting the assembly of units to heat and pressure include at least one heated cylinder press.  
           [0027]    According to another optional feature of the invention, said means (ii) include two or more heated cylinder presses.  
           [0028]    According to another optional feature of the invention, the means (iii) for, optionally, detaching and eliminating the film from the assembly of materials consists of a spooling roller.  
           [0029]    According to another optional feature of the invention, the means (iv) for continuously shaping the assembly of materials, optionally with or without the film, include several successive pairs of shaping rollers.  
           [0030]    According to another optional feature of the invention, the means (v) for maintaining the assembly of materials, possibly without the film, at a temperature essentially the same as that applied in stage c) until stage e) is completed, consist of a heater-softener and a re-heating apparatus.  
           [0031]    According to another optional feature of the invention, the re-heating apparatus includes a blower, whose outlet is heated by a heater and distributed by means of nozzles over the assembly of materials, particularly close to the areas in which shaping is to take place.  
           [0032]    According to another optional feature of the invention, the machine is arranged under controlled ambient conditions of temperature and humidity. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    Other features and advantages will appear in the following supplement to the description, when it is considered with reference to the attached drawings, in which:  
         [0034]    [0034]FIG. 1 represents, very diagrammatically, a segment of a section of profile or slat, with at least one part of its surface painted;  
         [0035]    [0035]FIG. 2 is a cross-section, very enlarged, of one part of a metallic strip covered with a primer coat;  
         [0036]    [0036]FIG. 3 is a cross-section, very enlarged, of one part of a coat of transfer paint, transitorily supported and adhering to an upper, temporary supporting and protective film;  
         [0037]    [0037]FIG. 4 is a cross-section, very enlarged, of one part of a metallic strip, like that of FIG. 1, covered by the coat of paint and the film of FIG. 2;  
         [0038]    [0038]FIGS. 5A and 5B are diagrammatic elevational views which, considered as a whole and in the order indicated, represent the machine according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0039]    With reference firstly to FIG. 1, this represents a segment of a section of a profile or slat P of the type to which the invention refers. The profile P is produced continuously by folding or continuous shaping from a flat metallic strip, and it may be seen that it includes pronounced folds (of 90° or even greater) corresponding with its different edges. At least an important part of the surfaces of profile P is painted, either with paint of uniform tone, or with any motif, for example an imitation of the grain of wood, stone, etc.  
         [0040]    FIGS.  2 - 4  diagrammatically represent very enlarged sections corresponding to the components of profile P in different states of manufacture. According to FIG. 2, the metallic strip  1   a  is covered on its anverse, that is on the side to be painted, by a primer coat  1   b , constituting a first material  1  (= 1   a + 1   b ). According to FIG. 3, a coat of paint  2   a  adheres transitorily to a detachable film  2   b  of temporary support and protection, constituting a second material  2  (= 2   a + 2   b ) of transfer painting. According to FIG. 4, the juxtaposition of both the first  1  and second  2  materials gives rise to an assembly of materials (1+2= 1   a + 1   b + 2   a + 2   b ) which make up the painted final profile.  
         [0041]    The following clarifications must be made with respect to the above description. Firstly, although this has not been represented to avoid making the drawing difficult to understand, the interface surfaces should be represented as far more irregular and, particularly in FIG. 4, the thickness of coats  1   b  and  2   a  could be less than those represented given that materials  1  and  2  have already been subjected to heat and pressure to make them adhere. Secondly, the film  2   b  always ends up being detached and eliminated from the final profile; sometimes, this elimination occurs immediately after the adhesion of the coat of paint  2   a  to the primer coat  1   b , while at other times the film remains until the time comes to install the final profile, in order to protect the coat of paint  2   a . Moreover, after detachment of the film  2   b , a coat of lacquer or varnish may be applied using conventional techniques to the coat of paint  2   a , which is not represented in FIGS.  2 - 4 . Finally, the reverse, that is the side of the strip  1   a  opposite to that which receives the primer  1   b , may have received, conventionally, a finishing covering, such as varnish or lacquer, by means of known techniques, which is not represented as it does not form part of the invention.  
         [0042]    The continuous application of covering coats, such as varnishes, lacquers and paints, to metallic surfaces, such as continuous strips of aluminium or the like, in such a way that a varnished, lacquered or painted strip is continuously obtained, is a conventional technique, although it may require complex know-how and expensive installations. Given that for continuous application to metallic strips of the known varnishes, lacquers and paints and for continuous application of the primer coat  1   b , whose use is recommended by the invention, it is possible to use the same known, general techniques and installations, the explanation of the invention will be on the basis of the use of spools of the first material  1  of FIG. 2, that is a metallic strip  1   a , already covered by the primer coat  1   b , without detailing the way in which this first material  1  is obtained. A spool of the first material  1  is represented in FIG. 5 a , with the reference  11 .  
         [0043]    It has already been stated that spools of the second material  2  can also be found in the market, for continuous painting of wooden or plastic profiles by transfer of the coat of paint  2   a  from the film  2   b . In the known state of the art and in contrast to what occurs in the present invention, this second material  2  is applied directly to the surface to be painted, without interposing the primer coat  1   b . Therefore, the explanation of the invention will be on the basis of the use of spools of the second material  2  of FIG. 3, without detailing its conventional manufacture. A spool of the second material  2  is represented in FIG. 5 a , with the reference  21 .  
         [0044]    The machine represented in FIGS.  a  and  b  includes, in a conventional framework, of which only some elements are shown, a frame  10  for supporting the spool  11  of the first material  1  of FIG. 2. The first material  1  passes, supported by the rollers  12  and  13 , and with its primer coat  1   b  facing upwards, through a pre-heater  14 .  
         [0045]    The framework also includes a support  20  for a spool  21  of the second material  2  of FIG. 3, which is taken by means of rollers  22  and  23  in such a way that it is juxtaposed with its coat of paint  2   a  facing upwards, to enter into contact with the primer coat  1   a  close to the entrance of a first cylinder press  30 .  
         [0046]    The press  30  includes a lower cylinder  31  and an upper cylinder  32  with a siliconized surface  33 . The press  30  also includes a means of forcing the upper cylinder  32  against the lower one  31 , a means which is represented by way of example in the embodiment illustrated, by means of a cylinder-piston system  34 . The upper part of the press  30  is surrounded by a heating hood  35 .  
         [0047]    At the exit of the press  30 , the assembly of materials  1  and  2  have substantially adopted the structure shown diagrammatically in FIG. 4 ( 1   a + 1   b + 2   a + 2   b ), with the exception made previously with respect to the thickness and irregularity of the profiles.  
         [0048]    The machine may include another or other additional presses, downstream from the cylinder press  30 , which is exemplified by the press  40 , which is identical or different in structure from the former. At the exit of the press  30  or  40 , the framework includes a frame  50 , with a roller  51  for detaching and collecting the film  2   b . This detachment will necessarily tale place when the upper part of the coat of paint  2   a  must receive another surface finish, such as a final varnishing. In the event that it does not have to receive this, the film  2   b  may remain in the assembly of materials  1  and  2  to protect the painted profile until its final handling or preparation. In the case in question, we will assume that the film  2   b  is detached in the roller  51 , in such a way that, as from the last press  30  or  40 , the assembly of materials has the structure  1   a + 1   b + 2   a.    
         [0049]    The assembly  1   a + 1   b + 2   a  is fed, through rollers  53  and  54  and a compensating arm  55 , into a heater-softener  60 , in which the non-metallic coats and, especially, primer coat  1   b  and the coat of paint  2   a  are softened, without destroying the adherent interfaces.  
         [0050]    Immediately after leaving the heater-softener  60 , the assembly of materials  1   a + 1   b + 2   a  are introduced into a continuous shaping section made up of a succession of pairs of conventional shaping rollers  70 ,  71 ,  72 ,  73 ,  74 , in which the assembly of material  1   a + 1   b + 2   a , which until now has been maintained as a flat strip, progressively receives its definitive shape, for example, in the form of profile P of a slat for a false ceiling, with a general shape similar to that represented in FIG. 1.  
         [0051]    Over the profile shaping section a re-heating apparatus  80  is arranged which, in the embodiment represented, includes a blower  81 , whose outlet is heated by a heater  82  and distributed by means of nozzles  83  and  84  over the material  1   a + 1   b + 2   a , particularly close to the areas in which folding will take place (close to the edges of the profile P of FIG. 1).  
         [0052]    The machine includes, of course, a control panel  90  to control temperatures, pressures and speeds of work of each component, as well as detectors of these parameters and other devices, which are known in themselves, to determine the cutting length of sections of the continuously painted profile which leaves the continuous shaping section. In particular, the real temperature of the material may be read by laser scanner arranged at one or two points of the path, as represented by way of example in FIG. 5A, with reference  91 .  
         [0053]    From the exit of the continuous shaping section, the profile P undergoes conventional treatments, such as the above-mentioned cutting into sections of determinate length in the shear  100 , varnishing of the upper surface of the coat of paint  2   a , which is shown in diagram in  110 , and transport to storage by, for example, roller transporters  111  and  112 .  
         [0054]    Of course, the working conditions must be chosen so that they do not affect the desired properties of the metal, nor those of the paint. By way of non-restrictive example, in the case of profiles for false ceilings:  
         [0055]    the metallic strip  1   a  may be made of aluminium, with a thickness of 400-600 μm;  
         [0056]    the primer coat  1   b  has a thickness of 2-6 μm;  
         [0057]    the coat of paint  2   a  has a thickness of 2-5 μm;  
         [0058]    the film  2   b  has a thickness of 2-3 μm;  
         [0059]    the heating temperature of the pre-heater  14  is about 150-200° C.;  
         [0060]    the heating temperature in the presses  30 ,  40  is about 130-200° C.;  
         [0061]    the heating temperature in the heater-softener  60  is about 130-170° C.;  
         [0062]    the temperature of the outlet air at the nozzles  83  and  84  is about 120-200° C.;  
         [0063]    the operating pressure of the cylinder-piston system  34  is about 800 bar.  
         [0064]    These values are only guidelines, as the differences between the batches of materials and variation in the ambient conditions of temperature and humidity may affect them to a great extent. Thus, it has been found advantageous that the materials  1  and  2  are fed to the machine after a period of storage in stabilisation chambers and that the machine itself is situated in an air-conditioned room, in which said ambient conditions may be controlled.  
         [0065]    As indicated above, working with metal, as is conventional, in wood or in synthetic resins, the continuous shaping of metal after direct application of the coat of paint  2   a  to the surface of the metallic strip  1   a  caused tearing of the coat of paint  2   a , so that metallic articles of high quality which were painted before continuous shaping to the final shape of the profile P, could not be manufactured, due to the poor quality (stretch marks, cracks, discontinuities) of the coat of paint  2   a , especially next to the edges of the folds. On the other hand, the use of the thick primer coat  1   b , treatment at high pressure and temperature throughout the process and, most especially, heating of the coats before and during continuous shaping allow profiles to be obtained which have been painted before reaching their final shape and which do not have surface defects due to the said shaping.  
         [0066]    It will be understood that the foregoing description has been given only as an example, to allow comprehension of the underlying idea of the invention, and that many changes and modifications are possible in each of the elements described, without departing from the scope of the protection defined in the attached claims. Thus, the type, arrangement and number of the means of heating, pressure application and control can vary widely with respect to what is described and represented by way of example in the foregoing description (for example, one or several heating tunnels could be used instead of independent hoods) and the spatial positions and other contingent elements could be replaced by other positions or elements which are technically equivalent.