EP2345518A1 - Method and device for coating workpieces - Google Patents

Abstract

The coating device (1) has a supplying device (10) for supplying coating material (12), and a pressing device (20) for pressing the coating material on a surface (2a) of a work piece (2). A conveying device (4) causes a relative movement between the pressing device and the work piece, and an energy source (30) applies energy on the coating material and/or the work piece. A controller (50) operates two energy producing sections i.e. lasers (30', 30''), of the energy source with operating parameters that are different from each other. An independent claim is also included for a method for coating a work piece. The energy producing sections are selected from a group consisting of a laser producing section, infrared producing section, ultrasound producing section, magnetic field producing section, microwave producing section, plasma producing section and gassing producing section, and the operating parameters are selected from a group consisting of energy intensity, energy direction and time of switching-on or switching off of the energy producing sections.

Description

Technical area

The invention relates to a device for coating workpieces, which are preferably at least partially made of wood, wood materials, plastic or the like, according to the preamble of claim 1, and a method using the device.

State of the art

For example, in the field of furniture and component industry workpieces are often provided on their surface with a coating material, such as an edge. The application of the coating material to the workpieces is often carried out by means of a suitable hot melt adhesive, which is applied, for example, in the hot, molten state on the edge or the workpiece. Alternatively, it is also possible to heat a pre-coated edge with hot melt by means of a hot air blower and so bring the hot melt adhesive to the desired melting temperature.

In addition, the reveals DE 10 2006 056 010 a coating method of the type mentioned, in which a provided on the coating material or the workpiece adhesive is heated or activated using a laser. This method has proved to be efficient because the adhesive can be specifically heated or activated.

However, further improvement potential in the coating of components consists in the fact that the joint between the coating material and the workpiece should be made as invisible as possible. For this purpose, the gap between the coating material and the workpiece should be as thin as possible, or a functional layer present on the joint (which may also be part of the coating material or of the workpiece) should be slightly impaired as far as possible. At the same time, however, the joint connection should have a sufficient strength so that the coating material securely adheres to the workpiece.

Presentation of the invention

It is therefore an object of the invention to provide a device and a method of the type mentioned above, which allow the least possible visible and at the same time sufficiently strong connection between the coating material and the workpiece.

This object is achieved by a device according to claim 1 and a method according to claim 12. Particularly preferred developments of the invention are specified in the dependent claims.

The invention is based on the finding that the adhesive potential of the adhesive or functional layers used is often not fully utilized. In order to achieve an improved utilization of the adhesion potential, it is provided according to the invention that in a generic device the energy source has at least two energy generating sections, wherein the control device is set up to operate at least two energy generating sections at least temporarily with at least one different operating parameter.

In this way, the bandwidth of the activation of the respective adhesive or of the respective functional layer can be significantly expanded, so that it is possible to work with a thinner adhesive layer or a smaller impairment of the functional layer while the strength of the joint connection remains undiminished. The result is thus an improved appearance of a coated workpiece and possibly even increased strength of the joint connection.

In addition, the inventors have found that the inventive provision of at least two energy generating sections, which are operable with at least one operating parameter different from each other, also results in an improved adaptability of the device according to the invention to changing operating conditions. For example, with the device according to the invention it is easier to switch between different coating materials, adhesives or functional layers and / or workpieces. This aspect is also of considerable importance in view of the ever growing, individual customer requirements.

Although in many cases it will be advantageous in the context of the present invention to work with at least two similar energy generating sections, it is alternatively provided according to the invention that at least two different energy generating sections are provided. In this case, it may happen that the two different power generation sections have no common operating parameters at all, but are operated in fundamentally different ways. By differentiating the power generation sections, the above-described effects that can be achieved by differentiating the operating parameters can be further developed. That's the way it is For example, it is possible to first prepare the material to be activated (or adhesively made) by a first power generation section, while the actual activation of the material takes place only in a second, downstream step by the second (or further) power generation section. As a result, the adhesion potential of the respective material to be activated can be utilized to a greater extent as described above, so that a visually appealing appearance can be achieved with the same strength of the joint connection.

The energy source can be constructed in the context of the present invention with a wide variety of types and number of energy generating sections, the term "energy" in the context of the present invention in a broad sense is to be construed. However, according to one embodiment of the invention, it is provided that at least one power generating section is selected from the group consisting of laser generating section, infrared generating section, ultrasonic generating section, magnetic field generating section, microwave generating section, plasma generating section, and gassing section. These power generation sections have proven to be particularly suitable in the course of investigations carried out by the inventors to add coating materials to workpieces.

The above enumeration makes it clear that in addition to classical energy sources and energy generating sections in question, apply the energy, for example, by a chemical reaction to the coating material, such as a source of fumigation. In this context, it should also be noted that the respective power generation section on the one hand can activate an agent already present as an adhesive and, on the other hand, also an agent which does not serve as an adhesive Make agent by energizing, chemical reaction or the like to an adhesive agent.

Each of the mentioned power generation sections has its specific advantages. Thus, a laser enables a particularly goal-oriented and speedy work, while infrared and plasma sources allow a broad-track operation and a good depth effect. Power generation sections with ultrasound, magnetic field and microwave work without contact and can still bring energy into the process during the pressing of the coating material. In particular, a magnetic field has a good depth effect. A fumigation-based energy source is particularly well-suited for forming a substance having adhesive properties by acting on and reacting with the coating material.

The operating parameters of the power generation sections, which are set differently according to the invention in at least two power generation sections, can be set in a variety of ways. According to one embodiment of the invention, however, it is provided that the independently adjustable operating parameters are selected from the group consisting of energy intensity, energy direction and temporal Energieerzeugungsveriaut, in particular also the time of switching on or off of a power generation section. These parameters can be used to increase the activation of the respective adhesive or the respective functional layer in a particularly effective manner. For example, in the activation of plastic materials, it has been shown that different molecular groups are activated by differentiation of the energy intensity, so that overall a larger proportion of the material to be activated can be addressed. With regard to the direction of the energy input, this can apply accordingly, for example by depending on Energeintragsrichtung different molecular groups of the material to be activated are addressed.

By differentiating the temporal energy generation curve, in addition to the effects mentioned above, other effects can also be achieved, for example by specifically influencing certain regions of the material to be activated with specific operating parameters which are changed for other regions of the material to be activated, so that an optimum joint connection is achieved results. For example, it is possible to work with different operating parameters in the edge regions of the joint connection than in core areas. Last but not least, an optimized joining connection can also be achieved by a differentiated connection or disconnection of individual or several energy generating sections.

A particularly advantageous combination of power generation sections is according to an embodiment of the invention, if at least two laser generating sections are provided. Laser production sections offer fast response, high variability, high precision, and many other benefits in activating joining materials. In addition, the combination of at least two laser generating sections, which are operated according to the invention with at least one different operating parameters, allows optimal utilization of the adhesion potential of the respective joining material, so that with optimal strength of the joint connection results in an attractive appearance and high durability of the joint connection.

The provision of at least two laser-generating sections can be achieved according to a development of the invention in that at least two laser-generating sections as separate ingots of a laser are provided. This gives a simple construction of the device according to the invention, which can be easily controlled.

Alternatively or additionally, it is provided according to a development of the invention that at least two Lasererzeu.gungsabschnitte are provided as separate laser. This opens up the possibility of greatly spreading the respective operating parameters as required and if necessary also of working with different laser function principles (eg diode lasers, CO ₂ lasers, etc.). Through such combinations, depending on the coating material, the material of the workpiece and the adhesive material can achieve the advantages described above.

According to a development of the invention, it is further provided that the control device is set up to operate at least two laser-generating sections with different laser power and / or laser wavelength. By staggering these operating parameters, the bandwidth of material activation can be increased, in particular for plastic materials to be activated. This can be explained by the fact that different molecular ranges of the material are addressed by different laser power and laser wavelength, resulting in an improved or broadened activation of the material. This makes a significant contribution to the solution of the underlying task.

Although the at least two energy-generating sections can in principle act independently on the material to be activated, according to a development of the invention it is provided that at least two energy-generating sections are arranged such that their energy application overlaps at least partially with the coating material and / or the workpiece. As a result, the interaction of the at least one different operating parameter of the at least two energy generating sections can be used particularly pronouncedly in order to solve the underlying problem.

Alternatively or additionally, according to a development of the invention, it is provided that the control device is set up to change at least one operating parameter in the course of a relative movement between the energy source and the coating material or the workpiece. In this way, a differentiation of the joint connection in different areas can be selectively achieved, for example, to make the edges of the joint connection visually appealing or even waterproof, while in the inner region of the joint connection lower requirements are met. Likewise, the temporal-spatial differentiation of the operating parameters can achieve different superposition effects, which allow the advantages already described above with regard to the activation of the respective material.

According to a development of the invention, it is additionally provided that the device has a measuring device, in particular a pyrometer, for measuring the amount of energy applied by the energy source to the coating material and / or the workpiece. In this way, the respective operating parameters can be adjusted particularly precisely to the materials to be processed and the respective boundary conditions, so that an optimum joining result results. It is also possible to "calibrate" the entire device in advance using the measuring device with respect to the materials currently being processed and / or with respect to the other boundary conditions in order to then use the respective power generation sections without or only during occasional operation of the measuring device. However, it is also possible by means of the measuring device continuously a Recording the amount of energy applied, for example, in terms of quality control.

In this case, the measuring device can be provided both as a separate component, but also integrated in the energy source (or in one or more power generation sections) and be integrated into the process, for example via a lens and / or mirror system.

The inventive method for coating workpieces using the device according to the invention is defined in claim 12. With this method, the advantages of the device according to the invention described above can be realized particularly pronounced.

Brief description of the drawings

Fig. 1

schematically shows a plan view of a coating apparatus 1 as a preferred embodiment of the present invention;

Fig. 2

schematically shows a plan view of a coating apparatus 1 as a second preferred embodiment of the present invention;

Fig. 3

shows schematically a view of the energy application characteristics on a coating material;

Fig. 4

schematically shows a view of other possible energy application processes on a coating material.

Detailed description of preferred embodiments

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

A coating apparatus 1 for coating workpieces 2 as a preferred embodiment of the present invention is shown in FIG FIG. 1 schematically shown in a plan view. The coating device 1 is used in the present embodiment for coating plate-shaped workpieces 2, which consist at least partially of wood-wood materials, plastic or the like, as used for example in the field of furniture and component industry today. This can be a variety of workpieces such as solid wood or chipboard, lightweight panels, sandwich panels, F`ußleistenleisten, profiles for profile coating, etc. act. It should be noted, however, that the present invention is not limited to such workpieces.

The coating device 1 initially comprises a conveying device 4, which in the present embodiment is designed as a continuous conveying device, for example in the form of a roller conveyor, belt conveyor or the like. The conveyor 4 is used to the workpieces 2 in a direction of passage (from left to right in FIG. 1 ) to promote. Alternatively, however, the invention can also be used in so-called stationary machines, in which the workpieces are stationary and processing units are moved. Also combinations of these machine concepts are possible.

In addition to the conveyor 4, a feeder 1fl is arranged for feeding a coating material 12, wherein the coating material is, for example, a map material for a narrow surface of the workpiece, but can also act as a cover material for a wide area or any other surface of the workpiece 2. The feeder 10 contains a supply of coating material 12, which may be made of a variety of materials, such as plastic, veneer, paper, cardboard, metal, etc., and various combinations thereof. In this case, the coating material may be provided, for example, in roll form (possibly in a cassette), but also in the form of individual sections.

In the present embodiment according to FIG. 1 however, it is a coating material containing an integral or discrete layer 14 which contains adhesive properties due to energy input. Such an integral coating material may for example be formed by a plastic material containing a layer 14 which exhibits adhesive properties due to the energy supply. In providing a discrete layer 14, the remaining coating material may in principle be made of any material. In any case, the discrete layer 14 is arranged on the side of the coating material 12 facing the workpiece 2.

The feeding device 10 feeds the coating material 12 to a pressing device 20 for pressing the coating material 12 against a surface 2 a of the workpiece 2. In the present embodiment, the pressing device 20 is a pressure roller (instead of a pressure roller belts, shoes or the like can be used, for example), which rolls on the surface 2a of the workpiece 2 and in this way the coating material 12 to the surface 2a of the workpiece 2 presses.

Furthermore, the coating device 1 comprises a power source 30 for applying energy to the Adhesive agent 14. In this case, the power source in the present embodiment has two power generation portions 30 'and 33 "formed by laser in the present embodiment.

For each of these power generation sections 30 'and 30 ", a variety of devices are contemplated within the scope of the present invention, such as laser, infrared source, ultrasound source, magnetic field source, microwave source, plasma source, fumigation source, etc. All of these power generation sections provide and direct energy in directed form adhesive agent 14, which is supplied as an integral or discrete part of the coating material 12. This focused energy is as in FIG FIG. 1 is passed through a line respectively from the power generating sections 30 'and 30 ", which passes through focusing means 32 and 36, respectively, which is adapted to apply the energy provided by the power generating sections 30' and 30" to selected areas of the adhesive 14 to be activated to judge.

In the simplest case, the focusing device 32 may be a lens. It should be noted, however, that different focusing devices 32 may be used, depending on the energy generating section 30 'or 30 ", wherein the focusing device may each be set up to adjust the scattering width and optionally also the intensity of the applied energy 32 the energy provided by the power source 30 in the area immediately upstream of a pressing portion 32 in which the coating material 12 is pressed against the surface 2a of the workpiece 2.

This operation of the power generation sections 30 'and 30 "and also of the focusing device 32, 36 is controlled by a control device 50, the control device in particular also controlling the operating parameters of the power generation sections 30' and 30". These operating parameters can be, for example, the intensity of energy, the direction of energy and the temporal energy generation curve, in particular the time at which a power generation section 30 ', 30 "is switched on or off Fig. 1 By way of example, the laser device 30 'and 30 "can be controlled by the control device 50 as an operating parameter, in particular the respective laser power and / or the laser wavelength.

According to the invention, the control of the operating parameters takes place in such a way that the energy generating sections are operated at least temporarily with at least one operating parameter that is different from each other. For example, the laser 30 'may be operated at a different wavelength than the laser 30 ", thus achieving enhanced activation of the layer 14 because the different wavelengths each address different molecular groups of the material For example, the laser power, etc. can be achieved.

As an alternative to this differentiation of at least one operating parameter in the case of similar energy generating sections, different types of energy generating sections 30 ', 30 "can also be used within the scope of the invention, as outlined above Mechanisms of action of the various energy generating sections can address, for example, different molecular groups of the material.

In any case, the operating parameters of the power generating sections should be matched to the properties and dimensions of the adhesive 14 and the relative velocity between the power source 30 and the adhesive 14. Against this background, the control device 50 can also evaluate information from sensors which monitor the operation of the coating device, for example sensors which are arranged in the region of the pressure region 22 and, for example, detect the temperature of the applied coating material 12.

For this purpose, the device 1 in the present embodiment further comprises one or more pyrometers 60, which is integrated into the beam path of the lasers 30 ', 30 "via half mirror 62. Alternatively, a pyrometer or other suitable measuring device may also be incorporated into the respective power generation section By means of the pyrometer, it is possible to measure the heating and thus the actual energy input into the material 14. The measurements can be carried out both continuously and at intervals, and it is also possible to determine the energy input in an upstream step and the machine to "calibrate" on this basis.

Based on this information, the controller 50 may set the operating parameters of the power generating sections 30 ', 30 ", and optionally also control the focussing device 32, 36 or other device parts.

The focusing device 32 is arranged in the present embodiment to oscillate as needed, for example in a direction perpendicular to the plane in FIG FIG. 1 , An oscillation movement is understood here to mean a vibration having a frequency of, for example, at least 10 Hz (eg 50 Hz). It ensures the Control device that the focusing device oscillates faster, the faster the relative movement relative to the workpiece 2.

Furthermore, in the present embodiment, the focusing device 32 can be moved together with the energy source 30, in a direction transverse to the direction of passage of the conveyor 4. This is particularly advantageous for large-scale coating tasks, such as for coating the wide surfaces of workpieces.

A second preferred embodiment of the coating apparatus 1 according to the invention is shown in FIG FIG. 2 schematically shown in a plan view. This is different from the one in FIG. 1 First embodiment shown primarily in that the adhesive or adhesively feasible means 14 is not supplied together with the coating material 12, but by means of an adhesive supply device in the form of an adhesive applicator roll 40 is applied to the surface 2a to be coated of the workpiece 2. Alternatively or additionally, it is of course also possible to apply the adhesive to the coating material 12 through the adhesive supply device 40.

The thus-applied adhesive 14 is then also activated or generated by energization by means of the energy source 30, again immediately upstream of a pressing region 22.

Although in FIG. 2 Of course, not shown, the coating apparatus 12 according to the invention may also comprise further means for supplying a liquid, such as, for example, a second adhesive applicator roll, an adhesive web feeder, or the like, and these different adhesive means preferably also provide different adhesives or adhesively feasible means 14 from each other. In this way, on the one hand on a single workpiece special effects can be achieved, on the other hand, it is also possible to use the different adhesive supply devices alternately as needed for different workpieces and boundary conditions.

In addition, the in Fig. 2 shown second embodiment in that the power generation sections 30 'and 30 "are integrated in a common laser device (power source) 30. In this case, one speaks of so-called" laser bars ", which are indeed integrated in a laser, but with different (and possibly The same can be operated with the operating parameters Fig. 2 embodiment shown achieve the same effects as described above with respect to in Fig. 1 embodiment shown have been described. In this case, instead of "Zaserbarren" also different types of power generation sections (which in turn may be similar or different from each other) are integrated in a common device unit. This also results in a simplified construction of the overall device according to the invention.

The operation of referring to Fig. 1 and 2 described embodiments of the device according to the invention will be described below by way of example with reference to FIG. 3 and FIG. 4 described. In both figures, a side view of a coating material 12 is shown in each case, and the areas of the coating material in which the coating material is acted upon by energy of a power generation section 30 'or 30 "are schematically indicated.

So is in Fig. 3 that the edge portions of the coating material 12 are energized with the energy of the power generation portion 30 "while the core portion of the coating material 12 is energized with the power generation portion 30". Alternatively, it is also possible that the entire surface of the coating material 12 is supplied with energy from the power generation section 30 "so as to overlap with the energization by the power generation section 30 ' The extent of the overlap can also be varied in the course of a relative movement between the energy source and the coating material.

At the in Fig. 4 schematically illustrated embodiment, the energy is applied to the coating material along a rectangular-sinusoidal path, whose course is indicated schematically by arrows. In this case, a plurality of power generation sections may follow this path, or only one power generation section may follow this path, while other power generation sections energize the coating material over a surface area or over a partial area.

In the course of the rectangular-sinusoidal profile, the operating parameters of one or more energy generating sections can be selectively varied, for example in the hatched areas of the coating material 12. In these hatched areas shown edge regions, for example, reduces the feed rate, the power of the energy source (eg laser power) increased or at all only on and off certain power generation sections done. In this way, the quality of the Joining joint in different areas of the coating material can be selectively influenced, so that it is possible to achieve an optimum combination of strength of the joint and visual appearance of the joint.

In addition, in the context of switching on or off of one or more power generating sections also advantageously be adapted to changing dimensions of the workpieces or coating materials.

Claims (13)

Device (1) for coating workpieces (2), which are preferably at least partially made of wood, wood-based materials, plastic or the like, comprising: a feeding device (10) for feeding a coating material (12), a pressing device (20) for pressing the coating material (12) against a surface (2a) of a workpiece (2), a conveying device (4) for bringing about a relative movement between the pressing device (20) and the respective workpiece (2), an energy source (30) for applying energy to the coating material (12) and / or the workpiece (2), and a control device (50) for controlling at least the energy source (30), characterized in that the power source (30) comprises at least two power generation sections (30 ', 30 "), the control device (50) being arranged to operate at least two power generation sections (30', 30") at least temporarily with at least one different operating parameter, or the power generation sections are different. An apparatus according to claim 1, characterized in that at least one power generating section (30 ', 30 ") is selected from the group consisting of laser generating section, infrared generating section, ultrasonic generating section, magnetic field generating section, microwave generating section, plasma generating section, and gassing section. Apparatus according to claim 1 or 2, characterized in that the independently adjustable operating parameters are selected from the group consisting of energy intensity, energy direction and time energy production curve, in particular also time of switching on or off of a power generation section (30 ', 30 "). Device according to one of the preceding claims, characterized in that at least two laser generating sections (30 ', 30 ") are provided. Apparatus according to claim 4, characterized in that at least two laser generating sections (30 ', 30 ") are provided as separate bars of a laser (30). Apparatus according to claim 4 or 5, characterized in that at least two laser generating sections (30 ', 30 ") are provided as separate lasers. Device according to one of claims 4 to 6, characterized in that the control device (50) is adapted to operate at least two laser generating sections (30 ', 30 ") with different laser power and / or laser wavelength. Device according to one of the preceding claims,
characterized in that at least two power generation sections (30 ', 30 ") are arranged such that their energy application to the coating material (12) and / or the workpiece (2) overlaps at least in sections. Device according to one of the preceding claims,
characterized in that the control device (50) is arranged to change at least one operating parameter in the course of a relative movement between the energy source (30) and the coating material (12) or the workpiece (2). Device according to one of the preceding claims,
characterized in that it further comprises a measuring device (60), in particular a pyrometer, for measuring the amount of energy applied by the energy source (30) to the coating material (12) and / or the workpiece (2). Method for coating workpieces (2), which preferably consist at least in sections of wood, wood-based materials, plastic or the like, using a device (1) according to one of the preceding claims, characterized in that at least two energy-generating sections (30 ', 30 ") be operated with at least one mutually different operating parameters. A method according to claim 11, characterized in that at least one operating parameter in the course of a relative movement between the energy source (30) and the coating material (12) or the workpiece (2) is changed. A method according to claim 11 or 12, characterized in that the by the energy source on the coating material (12) and / or the workpiece (2) applied amount of energy by means of a measuring device (60) at least temporarily measured and at least one operating parameter of at least one energy generating section (30 '. , 30 ") is determined taking into account the measured amount of energy.

Images