Patent Publication Number: US-11660632-B2

Title: Device for coating, in particular painting, the main surfaces of rigid panels with liquid products

Description:
BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to a device for coating, in particular for painting with liquid products, the main surfaces of rigid panels made of wood or other materials, such as for example chipboard or plastic materials. 
     In particular, the invention relates to a device for uniformly depositing a liquid coating substance, preferably paint, on the above-mentioned main surfaces of such panels. 
     2. The Relevant Technology 
     Parenthetically, in the present context, the term “panel” refers to a flat element in which two large surfaces parallel to each other are identified, defined below as main surfaces, between which there are lateral edges. 
     It is known that rigid panels made of wood or other material are suitably coated, preferably painted, to give the surfaces and edges a specific aesthetic appearance. 
     As regards, more specifically, the coating, or more specifically the painting of the main surfaces, this can be carried out manually, by means of one or more automated airbrushes, also called spray guns, installed on suitable structures below which the rigid panel passes, or, by means of one or more rollers resting on one of the main surfaces of the aforesaid rigid panel so as to transfer the liquid coating substance by contact. More specifically, as regards the above-mentioned airbrushes, each of them is equipped with a nozzle able to atomize the liquid product, more specifically the paint, towards the surfaces of the above-mentioned panels. 
     Obviously, the manual approach disadvantageously involves a high expenditure of time and does not ensure adequate precision in the distribution of the paint on the main surface. 
     Even the second approach which envisages the use of a plurality of spray guns does not lead to a uniform distribution of the paint over the entire main surface and, moreover, results in an increased waste of the atomized liquid substance since a good part of it is dispersed in the surrounding environment and is not deposited on the panel&#39;s surfaces. 
     Disadvantageously, this increases the level of pollution in the surrounding environment. 
     To overcome this last drawback, it is therefore necessary to place the painting device inside suitable painting booths isolated from the external environment and equipped with suction hoods to aspirate the sprayed product so as to avoid its diffusion into the environment. However, this solution requires considerable costs. 
     Furthermore, there is a huge economic loss due to the waste of the sprayed product that is not deposited on the panel&#39;s surfaces. 
     Moreover, this atomized liquid substance, disadvantageously, could accidentally be deposited also on the edges of the rigid panel, leading to the non-homogeneity of the paint layer present on the latter. 
     Finally, as regards the methodology which provides for the use of one or more rollers, it disadvantageously does not ensure the adequate distribution per square meter of the paint on the main surfaces of the rigid panel. 
     With regard to covering the edges, the prior art comprises the use of coating or painting devices comprising a painting head equipped with a reservoir, operatively connected by a delivery duct to a dispensing outlet located on the front of the painting head facing an edge of the panel. More specifically, this dispensing outlet has an essentially longitudinal development of a length at least equal to the thickness of the above-mentioned edge of the panel. In other words, this dispensing outlet is a longitudinal slot which defines a dispensing nozzle. Even more precisely, the position of the dispensing outlet is parallel with the direction of relative movement of the panel and of the painting head itself. In this way, when the panel passes, with this relative movement, close to the dispensing outlet, a coating layer is deposited homogeneously on it along its entire length. 
     These painting heads of the known type are also equipped, next to the dispensing outlet, with a suction inlet suited to aspirate the liquid product which comes out of the aforesaid dispensing outlet. This suction action facilitates the creation of a veil of liquid product between the dispensing outlet and the suction inlet suited to skim the edge of the panel, resulting in an amount of liquid product being laid which is sufficient to uniformly cover the edge itself and also prevents the runoff of the liquid product from the painting head. 
     In fact, the excess liquid product dispensed, and therefore not deposited on the edge of the moving panel (relative), is recovered by the suction inlet and returned to a reservoir for the liquid product. 
     In this way, the viscosity of the liquid product, the delivery rate through the slot, the speed of relative movement between the panel and the painting head, and the degree of vacuum at the suction point determine the thickness of the liquid product deposited on the edge of the panel. 
     From experimental tests carried out by the applicant, this last type of covering devices, disadvantageously, cannot be used also to cover, in particular to paint, the main surfaces of the rigid panel. 
     In fact, it is not sufficient to increase the length of the dispensing outlet and therefore the painting head at least to a value equal to the side of the panel perpendicular to the above-mentioned direction of relative movement, in order to obtain the at least sufficient quality painting of the main surfaces. 
     In particular, even if theoretically it would be intuitive to expect that an adequately dimensioned painting head facing one of the main surfaces might be used for the covering, in particular for the painting of the latter, in practice it has become clear that the distribution of the liquid product on the main surfaces, given that they are much more extensive than the edges, does not occur uniformly. This non-homogeneity, specifically, is found both in a parallel direction and in an orthogonal direction with respect to the above-mentioned direction of relative movement. More specifically, disadvantageously, using this type of devices, strips or bands are created on the main surface of the panel with an accumulation of liquid product greater than the accumulation that is found on adjacent strips or bands. 
     SUMMARY OF THE INVENTION 
     The present invention intends to overcome the aforesaid drawbacks. 
     More specifically, one object of the invention is to provide a covering device, in particular for painting, able to also distribute a liquid product on the main surfaces of a rigid panel. 
     Even more specifically, it is an object of the invention to provide a covering device, in particular for painting, able to uniformly distribute this liquid product on the above-mentioned main surfaces of a rigid panel. 
     These objects are achieved with the construction of a device in accordance with the main claim. 
     Further characteristics of the device of the invention are described in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects, together with the advantages mentioned below, will be highlighted in the description of some preferred embodiments of the invention that are provided, by way of non-limiting examples, with reference to the attached drawings, where: 
         FIG.  1    shows an axonometric view of the coating device, in particular for painting, according to a first preferred embodiment of the invention; 
         FIG.  2    shows a side view of the device of  FIG.  1   ; 
         FIG.  3    shows a top view of the device of  FIG.  1   ; 
         FIG.  4    shows a front view of the device of  FIG.  1   ; 
         FIG.  5    shows an axonometric view of a rigid panel; 
         FIG.  6    shows an axonometric view of the painting head according to a first preferred embodiment of the invention pertaining to the device of  FIG.  1   ; 
         FIG.  7    shows the painting head in cross-section, according to a vertical section plane, according to a first preferred embodiment of the invention, resting on a main surface of a panel; 
         FIGS.  8  and  9    both show details of the section of  FIG.  7   ; 
         FIG.  10    shows an axonometric view of the painting head of the invention according to a second preferred embodiment; 
         FIG.  11    is a cross-sectional view, according to a vertical section plane, of the painting head of the invention resting on a main surface of a panel, according to a second preferred embodiment; 
         FIGS.  12  and  13    both show details of the section of  FIG.  11   . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The device of the invention for coating, preferably for painting, with liquid products, preferably paints, of the main surfaces of rigid panels, is shown according to a first embodiment in  FIGS.  1  to  4   , where it is indicated as a whole by  1 . 
     The above-mentioned device  1 , as shown in  FIG.  1   , comprises a substantially horizontal support surface  2  to support a rigid panel P to be treated. 
     As previously stated, the term “panel” P refers to a flat element in which two large surfaces are identified, parallel to each other, defined as main surfaces SP 1  and SP 2 , between which there are lateral edges BL, as shown in  FIG.  5   . 
     These rigid panels P, as already said, may be made of wood, chipboard, plastic material or the like. 
     The device  1  of the invention, according to the first preferred embodiment, also comprises a painting head  3  which extends substantially along a longitudinal direction X, as can be seen in the detail of  FIG.  6   . The painting head  3  is located in the device  1  orthogonally to the direction of relative movement, indicated by A in  FIGS.  1 ,  2  and  3   , above the support surface  2  and the panel P placed on it. 
     According to the preferred embodiment described herein, the support surface  2  on which the panel P rests is a conveyor belt  21  configured to move the panel P forward along the above-mentioned movement direction A in the direction indicated by the arrow, while the painting head  3  is fixed by means of an arched structure  4  above the aforesaid support surface  2  so that the painting head  3  is, according to the longitudinal direction X, in a substantially fixed position during processing. 
     It is not excluded, however, that according to an alternative embodiment, the device comprises a static support surface  2 , and therefore the panel P, once it has been rested on such support surface  2 , is in turn kept in a fixed position, while the painting head  3  is connected to the aforesaid arched frame  4  in such a way as to be able to move relative to the support surface  2 , and thus the panel P along said direction of movement A. 
     Therefore, regardless of how the device  1  of the invention is structured, it is important that it allows the relative movement between the painting head  3  and the panel P, the main surface SP 1  of which must be covered, preferably painted. 
     Returning to the description of the first preferred embodiment of the invention, shown in  FIGS.  1  to  4   , according to a vertical section plane orthogonal to said longitudinal direction X and taking as a reference the direction of forward movement indicated by the arrow in the figures in question, the painting head  3  has on its face  5  suitable to be placed facing, during processing, the support surface  2  and therefore the main surface SP 1  of the panel P, a dispensing outlet  6  having a substantially longitudinal development, for the delivery of a liquid product, and an suction inlet  7  with a substantially longitudinal development, for the suction of this liquid product in-series. As seen above, this suction creates a veil of the liquid product between the two aforesaid mouths  6  and  7  and in contact with said main surface SP 1 . The vertical section of the painting head  3  is shown in  FIG.  7   . 
     In particular, preferably, starting from the left side of  FIG.  7    and taking as a reference the direction of movement indicated by the arrow A, the dispensing outlet  6  precedes the suction inlet  7  so that the direction of the flow of the liquid product between the two mouths substantially corresponds with the above-mentioned direction of movement A of the panel P. 
     According to the first embodiment of the invention, as shown in the section in  FIG.  8    of the painting head  3 , the first side surface  52  of the face  5 , defined between the first end  54  of the same face  5  and the first end  61  of the dispensing outlet  6 , is configured so that the distance d 4  between one of the points located around the same first end  61  of the dispensing outlet  6  and the support surface  2  is less than the distance dx between any other point belonging to the face  5  and the support surface  2 . 
     In particular, this distance d 4 , according to the invention, is smaller than the distance dx of any point of the intermediate surface  51  of the face  5  from the support surface, defined between the dispensing outlet  6  and the suction inlet  7 , and smaller than the distance dx of any point of the second side surface  53  of the face  5  from the support surface, defined between the second end  55  of the same face  5  and the second end  72  of the suction inlet  7 . 
     This characteristic advantageously allows the painting head  3  to rest on the main surface SP 1  of the panel P, during the forward movement of the latter, only at one of the points located around the above-mentioned first end  61 . In particular, the latter progressively touches the various areas of the main surface SP 1 , during the forward movement of the panel P, before those areas are covered by the liquid product. Therefore, advantageously, no part of the painting head  3  touches an area of the same main surface SP 1  after the same area has been painted. 
     Advantageously, this allows, during processing, the definition above the main surface SP 1  of the panel P and below the intermediate surface  51 , thus between the dispensing outlet  6  and the suction inlet  7 , of an empty channel  8  which extends substantially over the entire length of the painting head  3 . 
     The aforesaid empty channel  8  advantageously favors the process of suction of the liquid product by the suction inlet  7 . 
     This optimization, therefore, of the suction process allows the flow of the liquid product between the two mouths  6  and  7  to be kept constant and uniform, even in the presence of irregularities on the aforesaid main surface SP 1  of the panel  2 . 
     In other words, even in the case in which the main surface SP 1  is not totally flat, but for example is undulated or warped, and therefore if some of its points are at different distances from the above-mentioned dispensing outlet  6 , the definition of the aforesaid empty channel  8 , enabling the flow of the aforesaid liquid product to be maintained constant and uniform between the two mouths, would in any case compensate for such possible differences. Consequently, advantageously, this characteristic enables the coating, in particular the painting, of the above-mentioned main surface SP 1  to remain substantially constant over time and therefore along the direction of movement A and uniform throughout the length of the painting head  3  and therefore throughout the width of the panel P. 
     In other words, this characteristic of the painting head  3  of the device  1  of the invention makes it possible to prevent the appearance on the main surfaces SP 1  and SP 2  of the rigid panels P of strips or bands with an accumulation of liquid product greater than the accumulation that is found on adjacent strips or bands. 
     Moreover, the fact that the distances dx between each point of the second side surface  53  and the support surface  2  are also greater than the above-mentioned distance d 4 , allows, during the working phase, that is when the painting head  3  rests on the main surface SP 1  of the rigid panel P at the above-mentioned point around the first end  61 , the definition of a further empty channel  9 , indicated in  FIG.  7   , between the second end  72  of the suction inlet  7  and the second end  55  of the face  5 , which extends over the entire length of the painting head  3 . This further empty channel  9  ensures the constant and adequate flow of air towards the suction inlet  7 . Consequently, and advantageously, this aspect contributes to favoring a constant and uniform suction by the suction inlet  7  of the liquid product dispensed from the dispensing outlet  6 . 
     Furthermore, when the painting head  3  reaches the edge of the main surface SP 1 , in particular the above-mentioned first end  61  of the dispensing outlet  6  reaches the corner S of the panel P between the main surface SP 1  and the side edge BL, there could be the risk of the intermediate surface  51  touching the already painted corner S, degrading the aesthetic appearance of the latter. 
     However, the presence of the aforesaid vertical gap, particularly between the two ends  61  and  62  of the dispensing outlet  6 , due to the fact that the distance d 4  is less than the distance dx of any point of the intermediate surface  51  and of the second side surface  53  from the support surface, substantially favors the removal of the panel P from the painting head  3  before the aforesaid intermediate surface  51  is lowered at the level of the corner S of the surface SP 1 . 
     Preferably, according to the first embodiment of the device  1  of the invention shown in  FIG.  7   , along the entire length of the painting head  3  in the longitudinal direction X, the distance d 1  between the second end  62  of the dispensing outlet  6  and the support surface  2 , where the second end  62  of the dispensing outlet corresponds to a first end of the intermediate surface  51  of the face  5 , is greater than the distance d 2  between the first end  71  of the suction inlet  7  and the aforesaid support surface  2 , where the first end  71  corresponds to the second end of the same intermediate surface  51 . 
     Even more precisely, all the points of said intermediate surface  51  defined between the second end  62  of the dispensing outlet  6  and the first end  71  of the suction inlet  7  are positioned at a distance dx with respect to the support surface  2  between the distance d 1  and the distance d 2 . 
     This configuration allows the intermediate surface  51 , when the painting head  3  reaches the edge of the main surface SP 1 , in particular when the above-mentioned first end  61  of the dispensing outlet  6  reaches the corner S of the panel P between the main surface SP 1  and the lateral edge BL, to act as a sort of spatula that evens out any excess paint that might accumulate on the above-mentioned side edge BL. 
     In fact, in this area of the end of the panel P the most critical points are encountered in performing, on the part of the painting head  3 , the correct and homogeneous distribution of the paint, since the painting head  3  moves from a resting position on the main surface SP 1  of the panel P to a non-resting position on the same main surface SP 1 . 
     Preferably but not necessarily, according to the preferred embodiment of the invention, as shown in  FIG.  9   , this intermediate surface  51  rests on a first inclined plane π 1  with respect to the support surface  2 . Still more precisely, this first inclined plane π 1 , on which the intermediate surface  51  rests, intersects the support surface  2 , defining a first oriented angle α 1  negative with respect to the support surface  2  itself. 
     It should be noted that oriented angle, by definition and in particular in the present context, means an angle generated by a rotation of the starting side (in this case the support surface  2 ) around the vertex up to the ending side (in this case the three surfaces  51 ,  52  and  53  of the face  5 ). An oriented angle is said to be positive if the rotation is in the anti-clockwise direction, negative if in the clockwise direction. 
     It is not excluded that, according to different embodiments of the invention, this intermediate surface  51  does not rest on a plane, but is instead defined as a curve, provided however that it is in turn able to define the empty channel  8 . 
     Likewise, preferably, according to the first embodiment of the device  1  of the invention shown in  FIG.  8   , the painting head  3  is configured so that the distance d 5  between the second end  55  of the face  5  and the support surface  2  is greater than the distance d 6  between the above-mentioned second end  72  of the suction inlet  7  and the support surface  2 . 
     Even more specifically, the preferred embodiment of the invention provides that all the points of the second side surface  53  defined between the second end  55  of the face  5  and the second end  72  of the suction inlet  7  are positioned at a distance dx from the support surface  2  between the distance d 5  and the distance d 6 . 
     This characteristic enables the definition of the above-mentioned empty channel  9  with a shape such as to optimize the above-mentioned air flow towards the aforesaid suction inlet  7 , further favoring the constant and uniform suction by the suction inlet  7  of the liquid product dispensed from the dispensing outlet  6  in order to obtain a homogeneous deposition of the liquid product on the main surface SP 1  or SP 2  of the panel P. 
     According to the above-mentioned first preferred embodiment of the invention described herein, this second side surface  53  lies on a second inclined plane π 2  with respect to the support surface  2 . Even more in detail, this second inclined plane π 2 , on which the second side surface  53  lies, intersects with the support surface  2  defining a second oriented angle α 2  positive with respect to the support surface  2 . 
     It is not excluded, however, that, in alternative embodiments of the invention with respect to the first preferred embodiment, this difference in distance from the support surface  2  between the second end  72  of the suction inlet  7  and the second end  55  of the face  5  may not be defined. 
     Also, it is not excluded that in further alternative embodiments of the invention, this second side surface  53  may not lie on the aforesaid second inclined plane π 2 , but instead have a curved configuration, as long as this allows the definition of the above-mentioned further empty channel  9 . 
     The first preferred embodiment of the invention described herein further envisages that the first side surface  52  of the face  5 , defined between a first end  54  of the face  5  itself and the first end  61  of the dispensing outlet  6 , is configured so that the distance d 3  between the first end  54  of the aforesaid face  5  and the support surface  2  is greater than the distance d 4  between the first end  61  of the dispensing outlet  6  and the support surface  2  itself. 
     More precisely and preferably, all the points of the above-mentioned first side surface  52  defined between the first end  54  of the face  5  and the first end  61  of the dispensing outlet  6  are positioned at a distance dx from the support surface  2  comprised between the distance d 3  and the distance d 4 . 
     This geometric characteristic of the above-mentioned first side surface  52  enables the rotation, during calibration, of the painting head  3  along an axis of rotation X 1  parallel to the longitudinal development axis X and passing substantially through the point around the first end  62  of the dispensing outlet  6  from which the above-mentioned distance d 4  is measured. 
     The advantage of being able to perform this rotation of the painting head  3  is the fact that, in an easy and rapid manner before the start of the processing of the panel P, an operator can adjust the volume of the above-mentioned empty channels  8  and  9  and therefore, respectively, the flow rate of the liquid product that will flow between the dispensing outlet  6  and the suction inlet  7  and the flow rate of the air entering the same suction inlet  7 . 
     This fine adjustment thus advantageously enables the painting head  3  to be adjusted according to the type of liquid product used and/or to the type of panel P to be treated. 
     Preferably but not necessarily, according to the preferred embodiment of the invention, this first side surface  52  lies on a third inclined plane π 3  with respect to the support surface  2 . 
     Even more specifically, the above-mentioned third inclined plane π 3 , on which the first side surface  52  lies, intersects the support surface  2  defining a third oriented angle α 3  negative with respect to the support surface  2  itself. 
     It is not excluded that, according to different embodiments of the invention, the first side surface  52  is substantially parallel to the support surface  2 , and therefore it is not excluded that the device  1  of the invention does not allow for the possibility of tilting the painting head  3  to adjust it. In fact, in this case if the side surface  5  were positioned horizontally when the painting head  3  is placed in contact with the main surface SP 1 , there would be no margin to be able to rotate the painting head  3  around the above-mentioned axis of rotation X 1 . 
     Furthermore, it is not excluded that the above-mentioned first side surface  52  may not lie on a plane, but rather it may have a curved configuration, provided that, in this case, it enables the aforesaid rotation to be performed and therefore the painting head  3  to be adjusted. 
     The above-mentioned first preferred embodiment of the device  1  of the invention further envisages that on the face  5  of the painting head  3  a second dispensing outlet  20  is defined with a substantially longitudinal development. More specifically, this second dispensing outlet  20  is defined on the aforesaid second side surface  53  between the suction inlet  7  and the second end  55  of the second side surface  53 . 
     According to the invention, compressed air is supplied from the second dispensing outlet  20  during processing, if necessary, to compensate for any shortage or lack of inflow of air from the external environment through the second empty channel  9 . In other words, this second dispensing outlet  20  has the function of further facilitating the maintenance of constant and uniform suction by the suction inlet  7  of the liquid product supplied by the dispensing outlet  6 . 
     It is not excluded, however, that in alternative embodiments of the invention this second dispensing outlet is not defined on the face  5  of the painting head  3 . 
     Returning to the first embodiment of the invention, as shown in  FIG.  7   , the painting head  3  is configured in such a way that the dispensing outlet  6  is operatively connected by means of a supply duct  10  to a reservoir  11  for the storage of a quantity of liquid product necessary and sufficient to dispense it continuously and uniformly. 
     In particular, for this purpose both the supply duct  10  and the reservoir  11  extend longitudinally for a length substantially equal to the length of the dispensing outlet  6  in such a way as to enable the continuous and uniform flow of the liquid product along the entire length of the dispensing outlet  6  over time. 
     In the same way, according to the above-mentioned first preferred embodiment of the invention, the suction inlet  7  is operatively connected by means of a suction duct  12  to a suction reservoir  13 . In particular, the suction duct  12  and the suction reservoir  13  extend, according to the preferred embodiment of the invention, longitudinally for a length substantially equal to the length of the suction inlet  7  so as to enable a continuous and uniform suction over time along the entire length of the suction inlet  7 . 
     Furthermore, also as regards the second dispensing outlet  20 , the above-mentioned first preferred embodiment of the invention provides for it to be operatively connected by means of a second delivery duct  21  to a second reservoir  22  for the storage of compressed air and to a system to release the latter. 
     Finally, always according to the first preferred embodiment of the invention, the difference between the distance d 4  and the distance d 1  is around 3 mm, the difference between the distance d 1  and the distance d 2  is around 1 mm, the difference between the distance d 6  and the distance d 2  is equal to 1 mm, the intermediate surface is defined with a width of approximately 3 cm, the suction inlet too is defined with a width of approximately 3 cm, like the distance between the second end  72  of the suction inlet  7  and the second dispensing outlet  20 , and finally the paint dispensing outlet  6  is defined with a width of approximately 7.5 mm. 
     According to an alternative embodiment of the painting head  3  not shown in the figures, this could be connected in its front part, according to the direction of movement A, to a support roller. 
     This support roller, in particular, would be configured to keep the painting head  3  raised with respect to the panel P to be painted so that none of the points of the surface  5  rest on the main surface SP 1  or SP 2  of the panel P. This configuration would be necessary when the main surface SP 1  or SP 2  of panel P had already been painted with a protective paint and the painting head would be used to deposit the finishing paint layer. In fact, in this situation, in order to prevent the sliding contact of the painting head  3  on the main surface SP 1  or SP 2  from compromising the integrity of the above-mentioned layer of protective paint, it would be necessary to use this support roller. 
     As regards the coupling system between the painting head  3  and the arched structure  4  which supports it above the support surface  2 , as can be seen in  FIG.  1   , it is preferably a floating-type coupling system, which therefore allows the painting head  3 , once placed in a working position, to have a certain degree of freedom of movement substantially in a vertical direction with respect to the support surface  2  so as to be able to follow, once resting on the main surface SP 1  of the panel P, any discontinuities present on the latter precisely in the vertical direction. 
     In particular, this coupling system connects the lateral ends  3   a  and  3   b  of the painting head  3  to the first ends  14   a  and  15   a  of two longitudinal members  14  and  15 . In contrast, the opposite ends  14   b  and  15   b  of these longitudinal members  14  and  15  are hinged substantially on the lower part of the uprights  16  and  17  pertaining to the above-mentioned arched structure  4 . 
     Furthermore, these longitudinal members  14  and  15  are connected to the crosspiece  18  of the arched structure  4  by means of shock absorption means  19  able to guide the oscillation of the painting head  3  itself. 
     Furthermore, according to the above-mentioned first preferred embodiment of the invention, the painting head  3  is connected to the above-mentioned first ends  14   a  and  15   a  of the longitudinal members  14  and  15  so as to allow the rotation of the painting head  3  around a centrally defined rotation axis Y and parallel to the direction of movement A. 
     This further feature allows the painting head  3  to be able to adapt, during processing, to any irregularities present on the main surface SP 1  according to a substantially horizontal direction and orthogonal with respect to the direction of movement A. 
     Finally, as previously said, this painting head  3  is preferably able to be rotated with respect to the aforesaid longitudinal members  14  and  15  according to an axis of rotation substantially corresponding to the longitudinal axis X of the painting head  3  itself. 
     In fact, this enables the definition, during configuration, of the distances of the suction inlets  6  and of the dispensing outlet  7  from the main surface SP 1  to be treated, as well as of the dimensions of the above-mentioned two empty channels  8  and  9  in order to suitably and easily adjust the flow rate of the liquid product flowing between the aforesaid two mouths  6  and  7 . 
     A second preferred embodiment of the device of the invention will now be described, more specifically, a second embodiment of the painting head of the above-mentioned device, indicated in  FIGS.  10  to  13    with  103 . 
     This second embodiment of the invention, unless otherwise specified, has the same characteristics as the first embodiment described above. In this regard, all the features of the first embodiment of the invention which are considered to be verifiable also in the second embodiment of the invention, described shortly, will be indicated in  FIGS.  10  to  13    and in the following description with the same numerical reference used for the first embodiment of the invention, increased by 100. 
     In detail, this second embodiment differs, with respect to the first embodiment described above, substantially in the configuration of the lower face  105  of the painting head  103 , as shown in  FIGS.  10  to  13   . 
     In particular, the aforesaid painting head  103 , in correspondence with the above-mentioned face  105 , at least for a first segment  123  along the longitudinal direction X, envisages that the distance d 1  between the second end  162  of the dispensing outlet  106  and the support surface  102 , where the second end  162  of the dispensing outlet corresponds to a first end of the intermediate surface  151  of the face  105 , is greater than or equal to the distance d 2  between the first end  171  of the suction inlet  107  and the aforesaid support surface  102 , where the first end  171  corresponds to the second end of the same intermediate surface  151 . 
     According to this second preferred embodiment of the invention described herein, a plurality of the aforesaid first segments  123  is defined on the painting head  103  wherein the distance d 1  is greater than or equal to the distance d 2 , these first segments  123  being spaced apart from each other, as shown in  FIG.  10   . 
     More precisely, preferably but not necessarily, each of the above-mentioned first segments  123  has a width, according to the longitudinal direction X, between 1 cm and 5 cm. 
     As regards the remaining segments  124  of the intermediate surface  151  of the painting head  103  along the aforesaid longitudinal direction X in which the first segments  123  are not defined, they are shaped so that the distance d 1  between the second end  162  of the dispensing outlet  106  and the support surface  102  is smaller than the distance d 2  between the first end  171  of the suction inlet  107  and the above-mentioned support surface  102 . 
     Even more precisely, in correspondence with these remaining segments  124 , all points of the aforesaid intermediate surface  151  defined between the second end  162  of the dispensing outlet  106  and the first end  171  of the suction inlet  107  are placed at a distance dx with respect to the support surface  102  between the distance d 1  and the distance d 2 . 
     This configuration, and in particular the presence of one or more of the aforesaid first segments  123 , advantageously prevents, when the painting head  103  reaches the edge of the main surface SP 1 , in particular when the above-mentioned first end  161  of the dispensing outlet  106  reaches the corner S of the panel P between the main surface SP 1  and the side edge BL, the intermediate surface  151  from hitting the entire length of the painting head  103  against the side edge BL of the panel P. On the contrary, with this configuration, this side edge BL will come into contact only and exclusively with the above-mentioned first segments  123 . 
     This advantageously prevents the painting head  103  of the invention, at the end of the panel P, from invalidating the homogeneity of the distribution of the paint in an extended manner along the above-mentioned side edge BL. 
     Incidentally, it is important to point out that the embodiment just described which provides for the definition of the above-mentioned plurality of segments  123  along the longitudinal direction X at the second end  162  could itself be the subject of a claim without the first side surface  152  of the face  105  defined between a first end  154  and the dispensing outlet  106  having to be configured in such a way that the distance d 4  is less than the distance dx between any other point belonging to the face  105  and the support surface  102 . In fact, the presence of the segments  123  alone enables the above-mentioned technical advantages to be achieved. 
     Preferably but not necessarily, according to the preferred embodiment of the invention, as shown in  FIG.  13   , in correspondence with the aforesaid first segments  123 , the intermediate surface  151  rests on a first inclined plane π 101  with respect to the support surface  102 . Even more precisely, in correspondence with these first segments  123 , this first inclined plane π 101 , on which the intermediate surface  151  lies, intersects the support surface  102 , defining a first oriented angle α 101  which is negative with respect to the support surface  102 . 
     On the contrary, in correspondence with the remaining segments  124  of the intermediate surface  151  in which the aforesaid first segments  123  are not defined, the same intermediate surface  151  lies on a second inclined plane π 102  intersecting the support surface  102 , defining in this way a second oriented angle α 102  which is positive with respect to the support surface  102 . 
     It is specified, once again, that oriented angle, by definition and in particular in the present context, is meant to be an angle generated by a rotation of the starting side (in this case the support surface  102 ) around the vertex until it reaches the ending side (in this case the three surfaces  151 ,  152  and  153  of the face  105 ). An oriented angle is said to be positive if the rotation is in the anti-clockwise direction, negative if in the clockwise direction. 
     According to the above-mentioned second preferred embodiment of the invention described herein, this second side surface  153  lies on a third inclined plane π 103  with respect to the support surface  102 . Even more in detail, this third inclined plane π 103 , on which the second side surface  153  lies, intersects the support surface  102  defining a third oriented angle α 103  which is positive with respect to the support surface  102 . 
     It is not excluded, however, that, in alternative embodiments of the invention with respect to the preferred embodiment, this difference in distance from the support surface  102  between the second end  172  of the suction inlet  107  and the second end  155  of the face  105  may not be defined. 
     Moreover, it is not excluded that in further alternative embodiments of the invention, this second side surface  153  may not lie on the aforesaid third inclined plane π 103 , but instead have a curved configuration, as long as this allows the definition of the above-mentioned further empty channel  109 . 
     Furthermore, according to the above-mentioned second preferred embodiment of the invention, at the second end  172  of the suction inlet  107 , for at least one second segment  125  along the aforesaid longitudinal direction X, the distance d 6  between this second segment  125  and the support surface  102  is less than the distance between the remaining second segments  126  in which the aforesaid second segment  125  is not defined at the second end  172  along the above-mentioned longitudinal direction X and the support surface  102  itself. In other words, at the second end  172  according to the longitudinal direction X there is at least one second segment  125  protruding downwards with respect to the remaining second segments  126  of the same second end  172 , so that, also in this case, if the painting head  103  should hit the underlying panel P at the level of the second end  172 , the panel P would be touched only and exclusively by the aforesaid second segment  125 . This configuration, and in particular the presence of the above-mentioned second segment  125 , in the same way as the first segments  123  described above, prevents the painting head  103  of the invention, at the end of the panel P, from invalidating the homogeneity of the distribution of the paint in an extended manner along the above-mentioned side edge BL. 
     According to the preferred embodiment of the invention described herein, there are a plurality of the above-mentioned second segments  125  defined on the painting head  103  protruding downwards, these second segments  125  being spaced apart as shown in  FIG.  10   . 
     More precisely, preferably but not necessarily, each of the above-mentioned second segments  125 , along the longitudinal direction X, has a width between 0.5 cm and 5 cm. 
     Additionally, according to the second preferred embodiment of the invention, the plurality of the first segments  123  is staggered with respect to the plurality of the aforesaid second segments  125 , along the longitudinal direction X. 
     It is not excluded, however, that, according to an alternative embodiment, each first segment  123  may be aligned with a corresponding second segment  125  along the above-mentioned longitudinal direction X. 
     Also for the second preferred embodiment of the invention, the first side surface  152  of the face  105 , defined between a first end  154  of the face  105  itself and the first end  161  of the dispensing outlet  106 , is configured in such a manner that the distance d 3  between the first end  154  of the aforesaid face  105  and the support surface  102  is greater than the distance d 4  between the first end  161  of the dispensing outlet  106  and the support surface  102 . 
     More precisely, preferably, all the points of the aforesaid first side surface  152  defined between the first end  154  of the face  105  and the first end  161  of the dispensing outlet  106  are positioned at a distance dx from the support surface  102  between distance d 3  and distance d 4 . 
     This geometrical characteristic of the above-mentioned first side surface  152 , as in the case of the first embodiment of the invention, enables the rotation, during calibration, of the painting head  103  along a rotation axis X 1  parallel to the longitudinal development axis X and passing substantially through the point around the first end  162  of the dispensing outlet  106  from which the above-mentioned distance d 4  is measured. 
     The advantage of being able to perform this rotation of the painting head  103  is the fact that, in an easy and rapid manner before the start of the processing of the panel P, an operator can adjust the volume of the above-mentioned empty channels  108  and  109  and therefore respectively the flow rate of the liquid product that will flow between the dispensing outlet  106  and the suction inlet  107  and the flow rate of the air entering the suction inlet  107 . This fine adjustment thus advantageously enables the painting head  103  to be adjusted according to the type of liquid product used and/or to the type of panel P to be treated. 
     Preferably but not necessarily, according to the above-mentioned second preferred embodiment of the invention, the first side surface  152  lies on a fourth inclined plane π 104  with respect to the support surface  102 . 
     Even more specifically, the above-mentioned fourth inclined plane π 104 , on which the first side surface  152  lies, intersects the support surface  102  defining a fourth oriented angle α 104  which is negative with respect to the support surface  102 . 
     It is not excluded that, according to different embodiments of the invention, the first side surface  152  is substantially parallel to the support surface  102 , and therefore it is not excluded that the device of the invention does not provide for the possibility of tilting the painting head  103  to adjust it. In fact, in this case if this side surface  105  were positioned horizontally when the painting head  103  is placed in contact with the main surface SP 1 , there would be no margin to be able to rotate the painting head  103  around the above-mentioned axis of rotation X 1 . 
     Furthermore, it is not excluded that the above-mentioned first side surface  152  may not lie on a plane, but rather it may have a curved configuration, provided that, in this case, it enables the aforesaid rotation to be performed and therefore the painting head  103  to be adjusted. 
     Still according to the above-mentioned second preferred embodiment of the invention, the difference between the distance d 4  and the distance d 1  is selected so that it is around 3 mm, the absolute difference between the distance d 1  and the distance d 2 , both at the level of the first segments  123  and at the level of the remaining first segments  124 , is at most equal to 1 mm, the difference between the distance d 6  and the distance d 2  is equal to 1 mm, the height of the downward protrusion defined in the aforesaid second segments  125  of the second end  172  is around 1.5 mm with respect to the remaining second segments  126 , the intermediate surface is defined with a width of approximately 3 cm, the suction inlet too is defined with a width of approximately 3 cm, as is the distance between the second end  172  of the suction inlet  107  and the second dispensing outlet  120 , and finally the paint dispensing outlet  106  is defined with a width of approximately 7.5 mm. 
     As previously stated, all the characteristics explicitly described for the first embodiment of the invention which have not been restated also for the above-mentioned second embodiment, unless otherwise specified, must be considered implicitly present also for the above-mentioned second embodiment of the invention. 
     According to the foregoing, it is believed that the device  1  of the invention achieves all the set objects. 
     In particular, the object of constructing a coating device, in particular a painting device, able to distribute a liquid product also on the main surfaces of a rigid panel, is achieved. 
     Even more particularly, the object of the invention to construct a coating device, in particular a painting device, which is able to uniformly distribute this liquid product on the above-mentioned main surfaces of a rigid panel is achieved.