Abstract:
A device for fixing an edge material to a narrow side of a panel-shaped workpiece is provided, which has a feed mechanism for supplying the edge material to the narrow side of the workpiece, at least one infrared emitter for activating an adhesive layer, facing the workpiece, of the edge material, and a pressing mechanism for pressing the edge material onto the narrow side of the workpiece. In order to activate the adhesive layer of the edge material by means of infrared radiation using a reliable process without adversely affecting the visible face of the edge material, a radiation exposure zone with a specifiable size is arranged in the feed path of the edge material. In the exposure zone, the adhesive layer of the edge material is exposed to infrared radiation. The device has a guide mechanism for guiding the edge material through the radiation exposure zone.

Description:
[0001]    This application is a continuation of international application number PCT/EP2015/055286 filed on Mar. 13, 2015 and claims the benefit of German application number 10 2014 103 725.1 filed on Mar. 19, 2014, which are incorporated herein by reference in their entirety and for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a device for fixing a band-shaped or strip-shaped edge material to a narrow side of a panel-shaped workpiece, wherein the device has a feed mechanism for supplying the edge material along a feed path to the narrow side of the workpiece, and also at least one infrared emitter for activating an adhesive layer, facing the workpiece, of the edge material, and a pressing mechanism for pressing the edge material onto the narrow side of the workpiece. 
         [0003]    Devices for fixing a band-shaped or strip-shaped edge material are used for example in edge-processing machines. In such machines, a panel-shaped workpiece, in particular a wooden workpiece, is moved continuously in a transport plane, and with the aid of a fixing device of the above-mentioned type a band-shaped or strip-shaped edge material, which is frequently also referred to as an “edge veneer”, can be supplied to a narrow side of the workpiece which is oriented parallel to the direction of transport of the workpiece. The edge material has an activatable adhesive layer on its side facing the workpiece. During the supplying of the edge material to the narrow side of the workpiece, the adhesive layer is activated, and then the edge material is pressed against the narrow side of the workpiece and is thereby fixed to the narrow side. In many cases, the workpiece is then, together with the edge material fixed to the narrow side, sent for subsequent processing, in which regions of the edge material projecting over the workpiece in the direction of transport are separated off from the workpiece. 
         [0004]    Many different configurations of devices for fixing an edge material to a narrow side of a panel-shaped workpiece are known. Frequently, a heat-activatable hot-melt adhesive is used as the adhesive layer of the edge material. The hot-melt adhesive may be activated for example with the aid of hot air under pressure or alternatively with the aid of plasma irradiation. Such devices are known to the person skilled in the art for example from WO 2012/130224 A1 and DE 20 2009 009 253 U1. It has also already been proposed to use an edge material which consists of two preferably coextruded plastics-material layers of different hardnesses. One of the plastics-material layers forms an adhesive layer which can be activated by exposing it to laser radiation in order to bond the edge material to the workpiece. Such plastics materials are known for example from EP 1 163 864 B1 and EP 1 852 242 B1. 
         [0005]    The activation of the adhesive layer of the edge material with the aid of a laser beam is also known from DE 10 2006 056 010 B4. However, it necessitates a laser source which is cost-intensive and of complex design, and requires a not inconsiderable lead time before the device can actually be used for fixing the edge material. 
         [0006]    A considerable lead time is also necessary in order to activate the adhesive layer of the edge material with the aid of hot air under pressure or in general with the aid of a hot gas under pressure. Furthermore, this procedure too involves not inconsiderable costs. 
         [0007]    The equivalent also applies to the activation of the adhesive layer with the aid of plasma irradiation. The plasma irradiation requires not inconsiderable expense in terms of apparatus and likewise involves a considerable lead time before the adhesive layer of the edge material can actually be activated. 
         [0008]    It has also already been proposed to use an infrared emitter to activate the adhesive layer, for example in DE 20 2006 020 669 U1 or alternatively in DE 20 2009 009 253 U1. Infrared emitters are known per se to the person skilled in the art for heating purposes. When irradiating the edge material with infrared radiation, there is however the difficulty that merely the adhesive layer on the rear side of the edge material is to be activated by means of the infrared radiation, but the visible face of the edge material should not be adversely affected by the infrared radiation. 
         [0009]    It is therefore an object of the present invention to develop a device of the generic type such that the adhesive layer of the edge material can be activated with the aid of infrared radiation using a reliable process without adversely affecting the visible face of the edge material. 
       SUMMARY OF THE INVENTION 
       [0010]    This object is achieved according to the invention in a device of the type referred to first hereinbefore in that a radiation exposure zone with a specifiable size is arranged in the feed path of the edge material, in which zone the adhesive layer of the edge material is supplied with infrared radiation, and in that the device has a guide mechanism for guiding the edge material through the radiation exposure zone. 
         [0011]    In the device according to the invention, the adhesive layer of the edge material is exposed to infrared radiation merely within a specifiable radiation exposure zone. The size of the radiation exposure zone, i.e. the geometric extent thereof, is specifiable. The spatial delimitation of the radiation exposure zone makes it possible in a simply designed manner to specify the energy introduced into the edge material by the infrared radiation precisely, so that merely the adhesive layer is activated by the energy input, but there is no adverse effect on the visible face of the edge material. For the precise introduction of a specifiable amount of energy into the edge material, it is significant that the edge material which is guided through the radiation exposure zone does not unintentionally change orientation relative to the infrared radiation within the radiation exposure zone. According to the invention, therefore, the device has a guide mechanism which guides the edge material through the radiation exposure zone. Owing to the guide mechanism, the orientation of the edge material within the radiation exposure zone can be specified relative to the direction of the infrared radiation. This makes it possible, for example, to orient the infrared radiation substantially perpendicularly to the adhesive layer of the edge material. 
         [0012]    In a particularly preferred configuration of the invention, the size of the radiation exposure zone is changeable. This gives the possibility of adapting the size of the radiation exposure zone to the size of the edge material, i.e. in particular adapting it to the extent thereof in the vertical direction. Furthermore, the energy input which can be achieved by exposing the adhesive layer to infrared radiation within the radiation exposure zone can be changed by changing the length of the radiation exposure zone. By changing the size of the radiation exposure zone, adaptation of the device according to the invention to different edge material, in particular to different adhesive layers, can thus take place without for example the intensity and/or the wavelength of the infrared radiation emitted by the at least one infrared emitter having to be changed. 
         [0013]    It is advantageous if the radiation exposure zone is surrounded by a housing with an entrance for introducing the edge material and an exit for guiding the edge material out. The housing specifies the extent of the radiation exposure zone and protects the user of the device from infrared radiation. Safety requirements which arise from the use of the infrared radiation can thus be met in a simply designed manner. 
         [0014]    The guide mechanism preferably has at least one guide element which extends in the feed direction of the edge material along the radiation exposure zone, the edge material being movable along the at least one guide element. The at least one guide element ensures within the radiation exposure zone that the orientation of the edge material, in particular the orientation of the adhesive layer of the edge material, does not change unintentionally within the radiation exposure zone. The at least one guide element for this purpose extends in the feed direction of the edge material along the radiation exposure zone. 
         [0015]    It is advantageous if the at least one guide element contacts the edge material linearly. The linear contact prevents the guide element from being adversely affected by the adhesive layer. On its way through the radiation exposure zone, the adhesive layer is exposed to infrared radiation and is therefore increasingly activated. The greater the degree of activation of the adhesive layer, the more must care be taken that the adhesive layer which is at least partially already activated does not come into contact with the at least one guide element over a large area. Contact over a large area is prevented by the linear contacting. 
         [0016]    In a particularly preferred configuration of the invention, the at least one guide element has a fluted groove which receives an edge region of the edge material. The fluted groove may for example have a semicircular or V-shaped cross-section. The edge material may dip into the fluted groove with an edge region, in particular with a lower edge region, relative to the vertical, contacting the wall of the fluted groove only linearly and any changes in the material thickness of the edge material not adversely affecting the linear contacting. Fluctuations in the material thickness of the edge material thus result just as little in an adverse effect on the linear contacting as does the use of different edge materials which differ in their material thickness. 
         [0017]    The at least one guide element extends along the radiation exposure zone and is therefore exposed to the infrared radiation. It is advantageous if the at least one guide element can be cooled by means of a constrainedly guided cooling medium, for example with the aid of cooling air or with the aid of a cooling liquid. 
         [0018]    In a particularly preferred configuration of the invention, the at least one guide element has at least one cooling duct for a cooling medium. The cooling duct makes it possible to pass the cooling medium through the at least one guide element. This results in particularly effective cooling of the guide element. 
         [0019]    For example cooling water can be used for cooling the guide element. 
         [0020]    Preferably the at least one guide element is configured as a guide rail which forms a delimitation, oriented in the feed direction of the edge material, of the radiation exposure zone. The radiation exposure zone within which the edge material can be exposed to infrared radiation is thus delimited at least partially by the at least one guide rail. The guide rail thus takes on not only the function of guiding the edge material through the radiation exposure zone, but at the same time also forms a delimitation of the radiation exposure zone. 
         [0021]    It is particularly advantageous if the guide mechanism has two guide elements arranged spaced apart from each other which extend along the radiation exposure zone, the edge material being movable along the two guide elements. The two guide elements may in each case form a guide rail and the edge material may be displaced along the guide rails. The feeding of the edge material can be achieved by the feed mechanism and the use of the two guide rails ensures that the edge material does not unintentionally change orientation relative to the infrared radiation within the radiation exposure zone. 
         [0022]    It is particularly beneficial if the two guide elements form a lower and an upper guide rail which contact a lower edge and an upper edge of the edge material preferably linearly. 
         [0023]    As already mentioned, it is beneficial if the guide rails in each case have a fluted groove. The fluted groove preferably has a semicircular or V-shaped cross-section and receives an edge region of the edge material, the edge material contacting the fluted groove merely linearly. 
         [0024]    In an advantageous configuration of the invention, the two guide elements form an upper and a lower delimitation of the radiation exposure zone, the delimitations being oriented parallel to the feed path of the edge material. The guide elements may in each case form a housing part which surrounds the radiation exposure zone. 
         [0025]    The distance between the two guide elements, in a preferred configuration of the invention, is changeable, in particular changeable by means of a motor. This gives the possibility of guiding edge material with different vertical extents through the radiation exposure zone. The distance between the two guide elements can for this purpose be adapted to the extent of the edge material. In particular, provision may be made for the distance between the guide elements to be able to be changed with the aid of a motor, for example an electric motor, or alternatively with the aid of a piston/cylinder unit. 
         [0026]    Provision may for example be made for at least one of the guide elements to be arranged on a carriage which can be displaced in the vertical direction. The carriage can be displaced in specifiable manner with the aid of an electric motor, for example a servomotor, or alternatively with the aid of a piston/cylinder unit. 
         [0027]    In an advantageous configuration of the invention, the radiation exposure zone on its side remote from the at least one infrared emitter is delimited by at least one absorber element. The absorber element ensures that the infrared radiation cannot emerge unintentionally from the radiation exposure zone even when there is no edge material in the radiation exposure zone. If edge material is lacking, the infrared radiation is for the most part absorbed by the absorber element. 
         [0028]    The absorber element is beneficially plate-shaped. 
         [0029]    It is advantageous if the absorber element can be cooled with the aid of a constrainedly guided cooling medium, for example by means of compressed air or with the aid of a cooling liquid, in particular with the aid of cooling water. The provision of the cooling medium ensures that no impermissible heating of the absorber element occurs even in the case of continuous use of the device according to the invention. 
         [0030]    The absorber element may for example have at least one cooling duct for a cooling medium. The cooling medium, for example cooling water, can be passed through the cooling duct in order to cool the absorber element effectively. 
         [0031]    As already mentioned, the guide mechanism preferably has at least one guide element. In such case, it is beneficial if an adjustment mechanism is held on the rear side of the absorber element which is remote from the radiation exposure zone for adjusting the position of the guide element. For example, the carriage already mentioned above may be used as adjustment mechanism. 
         [0032]    The radiation exposure zone on its side facing the at least one infrared emitter is preferably delimited by a glass plate which is at least partially transparent to infrared radiation. The glass plate forms protection of the at least one infrared emitter from dust and dirt. In particular, the glass plate ensures that materials possibly evaporating from the adhesive layer within the radiation exposure zone do not readily reach the at least one infrared emitter. 
         [0033]    In an advantageous configuration, the glass plate is held exchangeably on a glass-plate holding unit. This, in a simple manner, gives the user the possibility of exchanging the glass plate if required or of removing it from the glass-plate holding unit for cleaning purposes. 
         [0034]    In an advantageous embodiment of the invention, a reflector is arranged on the rear side of the at least one infrared emitter which is remote from the radiation exposure zone. The reflector ensures that infrared radiation which is emitted by the at least one infrared emitter in the direction remote from the radiation exposure zone can be oriented at the radiation exposure zone. The reflector may for example be of ellipsoid or paraboloid form, by which the reflected infrared radiation can be parallelised, widened or bundled. 
         [0035]    It is particularly advantageous if the reflector is held exchangeably on a reflector holding unit. This gives the user the possibility of adapting the reflector to the edge material being used in each case. In particular, this gives the user the possibility of changing the size of the radiation exposure zone by changing the reflector. 
         [0036]    In order to keep radiation losses as low as possible, it is beneficial if the at least one infrared emitter is arranged immediately next to the radiation exposure zone, with merely a glass plate being positioned between the radiation exposure zone and the at least one infrared emitter. The distance between the at least one infrared emitter and the edge material which is guided through the radiation exposure zone can thereby be kept particularly low. Radiation losses are thereby reduced, so that the highest possible proportion of the infrared radiation emitted by the infrared emitter can be used for activating the adhesive layer of the edge material. 
         [0037]    Alternatively, provision may be made for at least one optical element for deflecting, focusing and/or widening the infrared radiation emitted by the at least one infrared emitter to be arranged between the at least one infrared emitter and the radiation exposure zone. The at least one optical element may for example be designed as a lens, a prism or as a mirror. The optical element makes it possible to orient the infrared radiation emitted by the at least one infrared emitter optimally at the adhesive layer of the edge material. 
         [0038]    The at least one optical element is preferably held exchangeably on an element support. This gives the possibility of adapting the orientation of the infrared radiation to the size of the edge material and in particular to the size of the respective adhesive layer by using different optical elements. 
         [0039]    Provision may also be made for the optical transmission properties of at least one optical element which is arranged between the at least one infrared emitter and the radiation exposure zone to be controllable. For example, provision may be made for the focal distance of a lens which is used as the optical element to be able to be changed. The change in the optical transmission property may take place for example manually or by supplying with an electrical control voltage. 
         [0040]    In an advantageous configuration of the invention, the at least one infrared emitter is held adjustably relative to the feed path of the edge material. This gives for example the possibility of changing the distance which the at least one infrared emitter assumes relative to the edge material. Alternatively or in addition, provision may be made for the orientation of the at least one infrared emitter relative to the feed path of the edge material to be able to be changed. For example, a rod-shaped infrared emitter extending substantially in the feed direction may be used, which emitter can be pivoted about a horizontal pivot axis oriented perpendicularly to the feed direction. As a result, the inclination of the rod-shaped infrared emitter relative to a horizontal plane can be changed. The angle of inclination can be adapted to the height of the edge material, in particular to the height of the adhesive layer of the edge material. The larger the adhesive layer, the larger is set the angle of inclination which the infrared emitter assumes relative to the horizontal plane, so that the adhesive layer during the feed movement of the edge material within the radiation exposure zone can be reliably exposed to infrared radiation over its entire height. 
         [0041]    The edge material can be supplied continuously to the workpiece, and in order to adapt the continuously supplied edge material to the length of the narrow side of the workpiece the device has a severing blade for separating off edge material. The edge material may be provided for example as rolls, and a desired length of the edge material can be separated off by means of the severing blade. 
         [0042]    In an advantageous configuration of the invention, the severing blade is mechanically uncoupled from the at least one infrared emitter. This ensures that mechanical vibrations which are produced upon edge material being separated off by the severing blade are not readily transmitted to the at least one infrared emitter. Adverse affecting of the at least one infrared emitter by the mechanical vibration caused by the severing blade can thereby be kept slight. 
         [0043]    In order to be able to attain a clean severing cut with the aid of the severing blade, it is advantageous if the severing blade is arranged relative to the feed path of the edge material in front of the entrance to the radiation exposure zone. This gives the possibility of still separating off the edge material before the adhesive layer of the edge material is activated by the infrared radiation. If the severing blade performs a severing cut in a region of the edge material in which the adhesive layer has already been activated, the activated adhesive layer could smear the severing blade or pass through the severing cut onto the visible face of the edge material. The edge material, in a preferred configuration of the invention, is therefore already separated off by means of the severing blade even before the adhesive layer is activated. 
         [0044]    Provision may however also be made for the severing blade to be arranged relative to the feed path of the edge material behind an exit from the radiation exposure zone. The severing blade may in such case have a non-stick coating, so that the risk of the activated adhesive layer adhering to the severing blade and being able to reach the visible face of the edge material via the severing blade can be kept low. 
         [0045]    It is particularly advantageous if the device has a screen which can be positioned between the radiation exposure zone and the at least one infrared emitter, which screen is movable back and forth between a covering position and a release position. In its covering position, the screen blocks the beam path between the at least one infrared emitter and the radiation exposure zone, so that no infrared radiation can pass into the radiation exposure zone. By positioning the screen in its covering position, it is thus possible to prevent the adhesive layer of an edge material located in the radiation exposure zone from being activated. In its release position, the screen releases the beam path between the at least one infrared emitter and the radiation exposure zone, so that the infrared radiation can pass unhindered into the radiation exposure zone in order to activate the adhesive layer of an edge material located in the radiation exposure zone. 
         [0046]    It is particularly beneficial if the screen is movable in the feed direction synchronously to the feed movement of the edge material to protect an edge-material region from infrared radiation. In such a configuration of the invention, the screen initially assumes its release position, so that the adhesive layer of edge material which is guided through the radiation exposure zone can be reliably activated. However, as soon as a specifiable length of the edge material has been guided through the radiation exposure zone, upon further feeding of edge material a rear—in the feed direction—edge-material region can be protected from infrared radiation in that the screen which is movable synchronously and parallel to the edge material is transferred out of its release position into its covering position. The screen is thus moved in the feed direction together with the edge material. The edge material can be guided through the radiation exposure zone and then behind the exit from the radiation exposure zone the region of the edge material which is protected from infrared radiation can be separated off from that region of the edge material which is exposed to the infrared radiation by means of a severing blade which is arranged behind the exit from the radiation exposure zone. The region of the edge material which is protected from infrared radiation can then be moved out of the radiation exposure zone counter to the feed direction and can then subsequently be reused for fixing to the narrow side of another workpiece, in which case the screen then assumes its release position and the edge material can be exposed to the infrared radiation. Losses of edge material can thus be kept low. 
         [0047]    Alternatively or in addition to a screen which is movable synchronously to the edge material in the feed direction, the device according to the invention may have a large number of infrared emitters which are arranged along the feed path of the edge material and can be switched on and/or off in succession synchronously to the feed movement of the edge material. This gives for example the possibility of switching off the infrared emitters arranged along the feed path in succession synchronously to the movement of the edge material as soon as such a length of edge material has been guided through the radiation exposure zone that the narrow side of a particular workpiece can be coated by the edge material. Thus, upon guiding edge material through, merely a front—in the feed direction—region of the edge material is still exposed to infrared radiation, whereas a rear region is no longer exposed. 
         [0048]    Behind the exit from the radiation exposure zone, the region of the edge material which has not been exposed to any infrared radiation can be separated off from the region of the edge material which has been exposed to the infrared radiation by means of a severing blade. The region which has not been exposed to radiation can then be pulled out of the entrance to the radiation exposure zone counter to the feed direction and then be reused for fixing to the narrow side of another workpiece. The loss of edge material upon activation of the adhesive layer thereof by means of infrared radiation can thus be kept very low. 
         [0049]    The intensity of the infrared radiation emitted by the at least one infrared emitter is beneficially controllable. This gives the possibility of adapting the intensity of the infrared radiation to the adhesive layer of the edge material being used in each case. If for example a relatively thick adhesive layer is used, the intensity of the at least one infrared emitter can be increased, and when a relatively thin adhesive layer is used the intensity of the at least one infrared emitter can be reduced. 
         [0050]    The intensity of the emitted infrared radiation can also be adapted to the absorption properties of the edge material, in particular to the absorption properties of the adhesive layer. This gives the possibility of selecting a different intensity for a very high absorption than for a low absorption. 
         [0051]    It is particularly advantageous if the intensity of the infrared radiation emitted by the at least one infrared emitter is controllable dependent on the feed rate of the edge material. This gives in particular the possibility of selecting a higher intensity for a high feed rate than for a low feed rate. Regardless of the feed rate, the same energy input into the activatable adhesive layer of the edge material can thereby be achieved for a specified length of the radiation exposure zone if the edge material is guided through the radiation exposure zone. 
         [0052]    It is particularly beneficial if the at least one infrared emitter is controllable dependent on the movement state of the edge material. This gives the possibility of switching off the at least one infrared emitter if the movement of the edge material stops for example because of a malfunction of the feed mechanism. An impermissibly high energy input into the adhesive layer of the edge material located in the radiation exposure zone is thereby avoided. 
         [0053]    The pre-heating time of the at least one infrared emitter is very short. Preferably the pre-heating time is approximately 1 second. This gives the possibility of only switching on the at least one infrared emitter when the moving edge material attains a specifiable position relative to the at least one infrared emitter. 
         [0054]    The at least one infrared emitter and in particular the electrical connecting contacts thereof experience heating during operation of the device. It is therefore beneficial if at least the electrical connecting contacts of the at least one infrared emitter can be cooled by a constrainedly guided cooling medium. As a result, in the event of continuous operation of the device a practically constant temperature above all of the electrical connecting contacts of the at least one infrared emitter can be achieved. For example, cooling air, or alternatively a cooling liquid, may be used as cooling medium. 
         [0055]    Provision may be made for not only the electrical connecting contacts of the at least one infrared emitter, but the entire infrared emitter, to be able to be cooled by a constrainedly guided cooling medium. For example, the at least one infrared emitter may be positioned in the path of flow of a cooling air. 
         [0056]    In an advantageous configuration of the invention, the at least one infrared emitter is arranged in a housing which has cooling ducts for a cooling medium. 
         [0057]    It is beneficial if the housing has at least one cooling-air duct which can be connected to a fan. By means of the fan, a cooling-air flow can be achieved in the at least one cooling-air duct, under the action of which flow at least the electrical connecting contacts of the at least one infrared emitter can be cooled. 
         [0058]    It is particularly beneficial if the at least one infrared emitter is controllable dependent on the pressure prevailing in the cooling-air duct and/or dependent on the flow rate of the cooling air prevailing in the cooling-air duct. This gives the possibility of switching off the infrared emitter and/or preventing the infrared emitter from being started up, as long as no cooling air is flowing through the cooling-air duct. For this purpose, for example a flow monitor may be used which switches off the at least one infrared emitter and prevents the at least one infrared emitter from being started up if it does not detect any cooling-air flow in the cooling-air duct. Provision may also be made for a pressure sensor to be arranged in the cooling-air duct, which sensor switches off the at least one infrared emitter and prevents the at least one infrared emitter from being started up, as long as there is no specified underpressure or no specified overpressure prevailing in the cooling-air duct. Overheating of the at least one infrared emitter due to lack of air cooling can be reliably avoided thereby. 
         [0059]    It is advantageous if the electrical connecting contacts of the at least one infrared emitter are connected in thermally conductive manner to at least one heat sink which is arranged in a cooling duct. Heat can be given off from the electrical connecting contacts via the heat sink. The heat sinks are beneficially arranged in a cooling-air duct which is in a flow connection with a fan. 
         [0060]    The following description of advantageous embodiments of the invention, in conjunction with the drawings, serves to explain it in greater detail. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0061]      FIG. 1 : is a perspective view of a first advantageous embodiment of a device according to the invention for fixing an edge material to a narrow side of a panel-shaped workpiece; 
           [0062]      FIG. 2 : is a top view of the device of  FIG. 1 ; 
           [0063]      FIG. 3 : is a sectional view of an irradiation unit of the device along the line  3 - 3  in  FIG. 2 ; 
           [0064]      FIG. 4 : is a partially separated perspective view of the irradiation unit of  FIG. 3 ; 
           [0065]      FIG. 5 : is a sectional view of the irradiation unit along the line  5 - 5  in  FIG. 3 ; 
           [0066]      FIG. 6 : is a sectional view, corresponding to  FIG. 3 , of a second advantageous embodiment of a device according to the invention for fixing edge material; 
           [0067]      FIG. 7 : is a perspective partial representation of a third advantageous embodiment of a device according to the invention for fixing edge material, and 
           [0068]      FIG. 8 : is a sectional view, corresponding to  FIG. 5 , of a fourth advantageous embodiment of a device according to the invention for fixing edge material. 
       
    
    
     DETAILED DESCRIPTION 
       [0069]      FIGS. 1 to 5  show schematically a first advantageous embodiment of a device according to the invention which is assigned overall the reference numeral  10 . The device  10  makes it possible to supply a band-shaped or strip-shaped edge material  12  to a panel-shaped workpiece  14 , in particular a wooden workpiece, which is moved in a direction of transport  16 . Units for moving the workpiece  14  are not shown in the drawings, since they are known per se to the person skilled in the art. 
         [0070]    The edge material  12  may be fixed to a narrow side  18  of the workpiece  14 . The edge material  12  for this purpose has on its rear side facing the workpiece  14  an adhesive layer  20 . The adhesive layer  20  cannot be recognised on the visible face  22  of the edge material  12  remote from the workpiece  14 . 
         [0071]    The edge material  12  may be unrolled from rolls, which are not shown in the drawings in order to obtain a better overview, and may be supplied continuously to the workpiece  14  with the aid of a feed mechanism  24 . The feed mechanism  24  has a feed roller  26 , which can be caused to rotate by a feed motor  28 . The feed roller  26  cooperates with a counter-roller  30  which is mounted in freely rotatable manner on a first machine frame  32 . By means of the feed roller  26  and the counter-roller  30 , the edge material  12  can be moved in a feed direction  34  along a feed path by the feed mechanism  24  to the narrow side  18  of the workpiece  14 . 
         [0072]    If the edge material  12  has reached the narrow side  18 , it can be pressed against the narrow side  18  by a pressing mechanism  36 . The pressing mechanism  36  has a pressing roller  38  and a plurality of subsequent pressing rollers  40  succeeding the pressing roller  38 . 
         [0073]    In the region between the feed mechanism  24  and the pressing mechanism  36  there is arranged on a second machine frame  42 , which is mechanically uncoupled from the first machine frame  32 , an irradiation unit  44  with a first infrared emitter  46  and a second infrared emitter  48 . The two infrared emitters  46 ,  48  are oriented parallel to each other and extend along the feed path of the edge material  12 . The first infrared emitter  46  is arranged above the second infrared emitter  48 . Both infrared emitters  46 ,  48  are rod-shaped and have offset electrical connection elements  50 ,  52  oriented perpendicularly to the feed direction  34 , which are each connected in thermally conductive manner to a heat sink  54 ,  56 . The two infrared emitters  46 ,  48  are surrounded by a cooling housing  58 . The cooling housing  58  is formed by a first housing part  60  which receives the two infrared emitters  46 ,  48  with the exception of their electrical connection elements  50 ,  52  and by a second housing part  62  which receives the electrical connection elements  50  and by a third housing part  64  which receives the electrical connection elements  52 . The first housing part  60 , just like the second housing part  62  and the third housing part  64 , forms a cooling-air duct. The cooling ducts are in a flow connection with an extraction hood  66 . To the extraction hood  66  can be connected a suction line, not shown in the drawings in order to obtain a better overview, via which line the extraction hood  66  is in a flow connection with a fan which is known per se and therefore is likewise not shown in the drawings. By means of the fan, a cooling-air flow can be obtained which extends through the first housing part  60  and also through the second housing part  62  and the third housing part  64  and also through the extraction hood  66 . In the extraction hood  66  is arranged a pressure sensor  68  which is electrically connected to a control unit not illustrated in the drawings. By means of the pressure sensor  68 , a pressure prevailing in the extraction hood  66  can be detected and can provide the control unit with a corresponding control signal. The control unit controls the supply of electrical energy to the two infrared emitters  46 ,  48 . The two infrared emitters  46 ,  48  can only be set into operation when a specifiable underpressure prevails in the extraction hood  66 . If the underpressure drops, the infrared emitters  46 ,  48  are switched off by the control unit. 
         [0074]    The first housing part  60 , which receives the infrared emitters  46 ,  48  with the exception of their electrical connection elements  50 ,  52 , has a rear wall  70  on which a reflector  72  is detachably held. The end wall of the first housing part  60  which lies opposite the rear wall  70  is formed by a glass plate  74  which is transparent to infrared radiation. The glass plate  74  is immediately adjoined by a radiation exposure zone  76  which is delimited in the vertical direction by a guide mechanism  78  and in the horizontal direction by the glass plate  74  and by an absorber element  80 , and through which the edge material  12  can be guided by the feed mechanism  24  to the narrow side  18  of the workpiece  14 . 
         [0075]    The guide mechanism  78  has a first guide element in the form of a lower guide rail  82  and a second guide element in the form of an upper guide rail  84 . The two guide rails  82 ,  84  extend in the feed direction  34  parallel to the two infrared emitters  46 ,  48  and are arranged spaced apart from each other. The two guide rails  82 ,  84  each have a cooling-water duct  86 ,  88  and can be cooled by the cooling water. Facing each other, the guide rails  82 ,  84  each have a fluted groove  90 ,  92  which is semicircular in cross-section, into which the edge material  12  can dip with a lower edge portion or an upper edge portion. The semicircular configuration of the fluted grooves  90 ,  92  ensures that the edge material  12  lies only linearly against the guide rails  82 ,  84 . 
         [0076]    The two guide rails  82 ,  84 , the glass plate  74  and the absorber element  80  form a housing of the radiation exposure zone  76  which surrounds the radiation exposure zone  76  with the exception of an entrance  94  and an exit  96 . 
         [0077]    The absorber element  80  is formed in two parts and comprises an inner absorber plate  98  which faces the two guide rails  82 ,  84  and on its rear side remote from the guide rails  82 ,  84  bears a meandering cooling-water duct  100 , and an outer absorber plate  102  which covers the cooling-water duct  100  and is screwed to the inner absorber plate  98 . 
         [0078]    The outer absorber plate  102  bears on its rear side remote from the inner absorber plate  98  an adjustment mechanism with a first guide profile  104  and a second guide profile  106 . The two guide profiles  104 ,  106  are vertically oriented and serve to mount a carriage  108  which can be displaced by a motor  110  along the guide profiles  104 ,  106 . 
         [0079]    The upper guide rail  84  is connected rigidly to the carriage  108  via a retaining clamp  112  which engages around the absorber element  80  and can be adjusted in the vertical direction together with the carriage  108  by the motor  110 . This gives the possibility of adapting the distance which the upper guide rail  84  assumes relative to the lower guide rail  82  to the vertical extent of the edge material  12 . 
         [0080]    The extent of the radiation exposure zone  76  can thus be changed by adjusting the upper guide rail  84 . 
         [0081]    In the embodiment illustrated in  FIGS. 1 to 5 , a severing blade  114  is arranged on the first machine frame  32  in the region between the feed mechanism  24  and the irradiation unit  44 , which blade can be moved back and forth by a drive unit  116  perpendicularly to the feed direction  34  in order to separate off the edge material  12 . 
         [0082]    As already mentioned, the edge material  12 , which is frequently also referred to as an “edge veneer”, can be supplied to the narrow side  18  of the workpiece  14 . On the way to the narrow side  18 , the adhesive layer  20  arranged on the rear side of the edge material  12  can be activated by being exposed in the radiation exposure zone  76  to infrared radiation which is emitted by the two infrared emitters  46 ,  48 . The intensity of the infrared radiation can be adapted to the feed rate of the edge material  12 . The greater the feed rate which is selected, the higher can the intensity of the infrared radiation be selected. 
         [0083]    The movement state of the edge material  12  can be detected by a movement sensor, in the example of embodiment illustrated by a rotary transducer  118 , which is rotatably mounted on the first machine frame  32  on the side of the feed mechanism  24  remote from the severing blade  114  and is electrically connected to the control unit, not shown in the drawings, of the device  10 . The rotary transducer  118  detects the movement of the edge material  12 . As long as the edge material  12  does not perform any movement, the energy supply to the two infrared emitters  46 ,  48  is interrupted because of the signal provided by the rotary transducer  118 . The energy supply to the infrared emitters  46 ,  48  is only provided if the rotary transducer  118  detects a movement of the edge material  12 . 
         [0084]    During operation of the device  10 , the absorber element  80  and also the two guide rails  82 ,  84  and the cooling housing  58  are cooled continuously, so that during continuous operation of the device  10  a substantially constant temperature occurs for the absorber element  80 , the two guide rails  82 ,  84 , the cooling housing  58  and also the infrared emitters  46 ,  48  and their electrical connection elements  50 ,  52 . 
         [0085]    The intensity of the infrared emitters  46 ,  48  can be controlled dependent on the degree of absorption of the edge material  12  used in each case, so that it is ensured that, during the time in which the edge material  12  is located in the radiation exposure zone  76 , the adhesive layer  20  is reliably activated, without thereby adversely affecting the visible face  22  of the edge material  12 . The guidance of the edge material  12  in the radiation exposure zone  76  is ensured by the two guide rails  82 ,  84 , which contact the edge material  12  merely linearly. 
         [0086]    In  FIG. 6 , a second advantageous embodiment of a device according to the invention for fixing edge material to the narrow side of a panel-shaped workpiece is shown in excerpts.  FIG. 6  shows merely a sectional view of the irradiation unit used in the second advantageous embodiment, which is assigned overall the reference numeral  130  in  FIG. 6 . The remaining components of the device illustrated in  FIG. 6 , just as in the advantageous embodiments discussed in greater detail below, which are illustrated in  FIGS. 7 and 8 , are identical to those of the device  10  which has already been discussed above with reference to  FIGS. 1 to 5 . With respect to these components, reference is made to the above statements in order to avoid repetition. 
         [0087]    The irradiation unit  130  differs from the irradiation unit  44  illustrated in  FIG. 3  in that an optical transmission equipment  132 , with optical elements  134 ,  136 , is arranged between the cooling housing  58  which receives the two infrared emitters  46 ,  48  and the radiation exposure zone  76 . By means of the optical transmission equipment  132 , the infrared radiation emitted in the direction of the radiation exposure zone  76  by the infrared emitters  46 ,  48  can be deflected, focused and/or widened. This gives the possibility of also changing the beam path of the infrared radiation emitted by the infrared emitters when changing the distance between the two guide rails  82 ,  84 . If the distance between the guide rails  82 ,  84  is reduced, the infrared radiation can be focused. If the distance between the guide rails  82 ,  84  is increased, the infrared radiation can be widened. 
         [0088]    The second advantageous embodiment of the device according to the invention illustrated in  FIG. 6  furthermore differs from the device  10  discussed above in that the cooling housing  58  with the infrared emitters  46 ,  48  arranged therein can be pivoted about a horizontal pivot axis  138  oriented perpendicularly to the feed direction  34 . This gives the possibility of inclining the rod-shaped infrared emitters  46 ,  48  relative to a horizontal plane, so that the infrared emitters  46 ,  48  in the region between the two guide rails  82 ,  84  extend over an increased height, and as a result edge material  12  which extends in the vertical direction over a relatively great height can also be reliably exposed to infrared radiation over the entire height. 
         [0089]    In  FIG. 7 , a third advantageous embodiment of a device according to the invention for fixing edge material to the narrow side of a workpiece is illustrated schematically,  FIG. 7  merely showing an alternative configuration of an irradiation unit which is assigned overall the reference numeral  150  and a severing blade  154 . As already mentioned, the remaining components of the third advantageous embodiment of a device according to the invention are identical to those of the device  10  schematically designated in  FIGS. 1 to 5 . The irradiation unit  150  differs from the irradiation unit  44  discussed above with reference to  FIGS. 1 to 5  in that a screen  152  can be positioned between the cooling housing  58  and the radiation exposure zone  76 , which screen is movable back and forth synchronously to the feed movement of the edge material  12  between a release position and a covering position. The screen  152  can be moved out of its release position in the feed direction  34  into its covering position by means of a drive unit not shown in the drawings, preferably by means of an electric motor. By means of the screen  152 , thus edge material, in particular the adhesive layer  20  of the edge material, can be protected from infrared radiation within the radiation exposure zone  76 . This gives the possibility of exposing the edge material  12  to infrared radiation on the rear side only over such a length as is necessary for coating the narrow side  18  of a particular workpiece  14 . Excess edge material can be covered within the radiation exposure zone  76  by the screen  152 . The severing blade  114  arranged in the first embodiment between the feed mechanism  24  and the irradiation unit  44  can in such case be replaced by the severing blade  154  positioned behind the exit from the radiation exposure zone  76 , i.e. in the region between the irradiation unit  150  and the workpiece  14 . Once the edge material has passed through the radiation exposure zone  76 , the edge material  12  can be separated off by means of the severing blade  154  which succeeds the radiation exposure zone  76 . Excess edge material can be covered by the screen  152  and can therefore be moved back counter to the feed direction  34  after separating off, so that it can be used for coating the narrow side of a further workpiece. The loss of edge material can thereby be kept particularly low. 
         [0090]      FIG. 8  schematically illustrates an irradiation unit  160  of a fourth advantageous embodiment of a device according to the invention for fixing edge material to the narrow side of a workpiece. The irradiation unit  160  differs from the irradiation unit  44  described above with reference to  FIGS. 1 to 5  in that instead of the first infrared emitter  46  and the second infrared emitter  48  oriented parallel to the first infrared emitter  46  a large number of infrared emitters  162  which are each vertically oriented and arranged in series in the feed direction  34  are used, which extend in the vertical direction and can be switched on and/or switched off in succession synchronously to the feed movement of the edge material  12 . In a similar manner as by the use of the screen  152 , it can be ensured by the infrared emitters  162  which can be switched off in succession synchronously to the feed movement of the edge material  12  that excess edge material is practically not exposed to infrared radiation. A severing blade  154  (not shown in  FIG. 8 ) can be arranged in the same manner as in the configuration schematically illustrated in  FIG. 7  in the region between the irradiation unit  160  and the workpiece  14 . Excess edge material can be separated off by means of the severing blade  154  and then be pulled out of the radiation exposure zone  76  counter to the feed direction  34 , the excess edge material not having been exposed to infrared radiation, since the infrared emitters  162  were switched off synchronously to the movement of the edge material upon entry of the excess edge material into the radiation exposure zone  76 . The excess edge material can thus be used for coating the narrow side of a further workpiece. The advantageous embodiment of the device according to the invention illustrated in  FIG. 8  is thus also distinguished by a particularly low loss of edge material. Upon introduction of edge material into the radiation exposure zone, the infrared emitters  162  can beneficially be switched on in succession synchronously to the feed movement of the edge material  12 .