Device and method for melting and applying a coating agent to a surface of a workpiece

Abstract

The present invention relates to a device (100) for melting and applying a coating agent (102), in particular a hot melt glue, to a surface (O) of a workpiece (104), the device (100) comprising: - a metering roller (106) for metering and tempering the coating agent (102); - an application roller (108) for applying the coating agent (102) to the surface (O) of the workpiece (104); - an inductive tempering unit (110) arranged inside the metering roller (106) for inductively tempering at least one segment (107.i) of the metering roller (106); and - a control unit (112) for controlling and / or regulating the inductive temperature control unit (110). Furthermore, a method for melting a coating agent by means of such a device (100) is specified

Description

The present invention relates to a device for melting and applying a coating agent, in particular a hot glue, to a surface of a workpiece. The invention further relates to a method for tempering an inductive tempering unit in such a device.The heating of devices and in particular of their rollers for melting and applying coating agents, in particular hot glue, is usually carried out by external heating devices or with heating cartridges, which are introduced into the roller or with a heat transfer medium. The heat transfer medium can be water or a thermal oil, for example.The heat transfer medium is conducted via rotary feedthroughs, flange connections and / or hoses into the rollers in order to heat their surface.However, such solutions have possible disadvantages.Disadvantages are, for example, the size of the heating devices, a poor energy transfer rate and the susceptibility to faults in the hose and / or flange connections.Furthermore, a temperature distribution on the surface of the roller is often very inaccurate.All these disadvantages likewise have a disadvantageous effect on the melting of the coating composition.It is therefore the object of the present invention to specify a device and a method with the aid of which reliable and efficient heating of the device and thus efficient melting of the coating agent is made possible.The object directed to the device is achieved according to the invention by a device having the features of the independent device claim. The object directed to the method is achieved according to the invention by a method having the features of the independent method claim.Advantageous embodiments, developments and variants are specified in the dependent claims.The advantages and preferred embodiments listed with regard to the device are to be transferred analogously to the method and vice versa.Specifically, the object is achieved by a device for melting and applying a coating agent to a surface of a workpiece.The coating agent is in particular a hot glue.The device has a metering roller for metering and for controlling the temperature of the coating agent.The device further comprises an application roller for applying the coating agent to the surface of the workpiece.The metering roller and the application roller are preferably arranged in such a way that they form between them a gap through which the coating agent can flow in order subsequently to be melted or applied to the surface of the workpiece.The metering is preferably effected by setting a relative distance of the metering roller from the applicator roller. As a result, the gap is enlarged or reduced and thus enables metering of the coating agent.Furthermore, the device has an inductive temperature control unit which is arranged in the interior of the metering roller. The inductive temperature control unit serves for inductively controlling the temperature of at least one segment of the metering roller.The term "inductive temperature control unit" can be understood here to mean a temperature control unit which is heated inductively, that is to say via a magnetic field. The temperature control unit thus does not require any external components, such as a heating device or a heat transfer medium.The term "segment" can be understood in the sense of this application as a section of the metering roller viewed in the axial direction. In a simplest embodiment, the metering roller has only one segment which comprises the entire (surface of the) metering roller.For controlling and / or regulating the inductive temperature control unit, the device has a control unit.The inductive temperature control unit makes it possible to heat the metering roller without the disadvantages mentioned above and thus to realize a reliable and efficient device for melting a coating agent and in particular a hot glue.According to one embodiment of the device, the metering roller has a plurality of segments arranged in an axial direction. The metering roller preferably has three, in particular five and especially six segments.Furthermore, the temperature control unit has a plurality of temperature control elements.Preferably, a temperature control element is arranged in each segment here for, in particular individual, temperature control of the segments. Analogously to the aforementioned examples relating to the number of segments, the temperature control unit can preferably have three, in particular five and specifically six temperature control elements. This means that a temperature control element is assigned to each segment and therefore preferably the number of temperature control elements corresponds to the number of segments of the metering roller.The temperature control elements are preferably inductors which heat the metering roller in the manner of induction heating.The temperature control unit is thus to be understood as a generic term for the "heating component" of the device which has the temperature control elements and other components, such as cables.By dividing the metering roller into a plurality of segments in conjunction with the assignment of one temperature control unit per segment in each case, reliable and segment-dependent heating of the metering roller is made possible.It can be advantageous if the control unit is connected to each of the temperature control elements for controlling and / or regulating the temperature control elements, in particular for individually controlling and / or regulating the temperature control elements.According to a preferred embodiment, the control unit is configured to set and / or adjust a uniform temperature along the surface of the metering roller.Alternatively or additionally, the control unit can be configured to set and / or adjust a temperature gradient along the surface of the metering roller.The term "temperature gradient" can be understood in the sense of this application, but not by way of limitation, to mean that a temperature distribution along the surface of the metering roller is set and / or adjusted. For example, a temperature profile can be set and / or adjusted according to which the highest temperature prevails at the ends of the roll and this temperature decreases in the direction of the center of the roll or vice versa.It can be advantageous if the device has a temperature sensor. The temperature sensor preferably serves for detecting a temperature of the surface of the metering roller and / or of the application roller.In particular, the temperature sensor serves for detecting a temperature of the surface in each segment of the metering roller.For example, a drilling channel parallel to the axis of the metering roller can be provided, into which a plurality of temperature sensors of the temperature sensor are introduced side by side with different lengths. The temperature sensors preferably have such a length that they each end in one of the segments in order to detect the temperature of the surface there.Alternatively, it is conceivable that several drilling channels are provided, into each of which a temperature sensor is introduced. It can be advantageous if the number of drilling channels together with temperature sensor corresponds to the number of segments in order to individually detect the temperatures of the surfaces in the individual segments.Furthermore alternatively or additionally, the metering roller can have a central passage (viewed radially), into which one or more temperature sensors are introduced. The one or more temperature sensors then branch off preferably radially in the direction of the surface of the metering roller or of the segments of the metering roller and record the temperature "from the inside".In one embodiment, the control unit is configured to control and / or regulate the inductive temperature control unit, in particular each temperature control element, based on a signal of the temperature sensor.It is thus conceivable, for example, that during operation of the device the temperature of the metering roller can be adjusted, i.e. increased or decreased.According to an alternative or supplementary embodiment of the device, the control unit is configured to control and / or regulate the inductive temperature control unit, in particular each temperature control element, based on a characteristic diagram, in particular based on a current characteristic diagram of the inductive temperature control unit.This embodiment is based on the advantageous idea that a specific temperature is set when a predefined current is applied to the temperature control unit, in particular the temperature control elements. In general terms, this means that the higher the current with which the temperature control unit and in particular the temperature control elements are subjected, the higher the temperature that is established.It is thus conceivable that a specific temperature value can be assigned to specific current values and therefore the temperature can preferably be deduced on the basis of the set current value. From this, a (current) characteristic map can then be created, which can preferably be used by the control unit for control and / or regulation.The (current) characteristic map is preferably stored on the control unit. Alternatively, the control unit can have a wired or wireless data connection, for example an Ethernet connection, to an external entity, via which the control unit receives parameters to be set.The external entity may be, for example, but not limited to, a database.Furthermore alternatively or additionally, the control unit can be configured to control and / or regulate the inductive temperature control unit, in particular each temperature control element, based on a parameter of the coating agent.In particular, the parameter of the coating agent is a viscosity and / or a temperature of the coating agent.Preferably, the temperature of the metering roller has a value in the range from 100°-300° C., in particular in the range from 120°-250° C., especially in the range from 140°-200° C. and advantageously in the range from 150°-180° C., as a result of the heating by means of the temperature control unit.These temperature values preferably correspond to the processing temperatures of suitable hot glues, so that reliable and efficient processing, i.e. melting to the surface, is thus made possible.Furthermore, it is advantageous that, by using the inductive temperature control unit, temperatures and / or temperature ranges that are not possible with the already known devices can also be set. For example, the maximum adjustable or adjustable temperature is limited at 140° C. in the case of water as heat transfer medium. However, with the device according to the invention, temperatures which are higher than 140° C. can also be set and / or adjusted.It can be advantageous if the inductive temperature control unit has a power in a range between 1.5 kW and 40 kW, in particular between 2 kW and 35 kW, especially between 4 kW and 25 kW, advantageously between 5 kW and 20 kW.Such power ranges have proven advantageous, for example, in order to achieve the aforementioned temperature ranges.According to an alternative embodiment, the application roller can have a further inductive temperature control unit. In this embodiment, both the metering roller and the application roller thus have an inductive temperature control unit.The efficient and reliable melting of the coating composition is thus advantageously influenced.It can furthermore be advantageous if the device has a smoothing roller. The smoothing roller preferably serves to smooth the coating agent after it has been melted and applied by the application roller.Particularly preferably, the smoothing roller likewise has an inductive temperature control unit in order to be temperature-controlled, in particular heated, by said smoothing roller.The inductive temperature control unit of the application roll and / or the inductive temperature control unit of the smoothing roll can preferably likewise be controlled and / or regulated by the control unit in accordance with the type described above.Specifically, the object directed to the method is achieved by a method for tempering an inductive tempering unit in a device for applying a coating agent, in particular an adhesive, to a surface of a workpiece.The device can be, in particular, the device already described above.The inductive temperature control unit is preferably arranged in the interior of a metering roller.The method comprising the steps of:controlling and / or regulating a temperature of a surface of the metering roller based on a signal of a temperature sensor by a control unit; and / orcontrolling and / or regulating a temperature of a surface of the metering roller based on a characteristic diagram, in particular based on a current characteristic diagram of the inductive temperature control unit, by the / a control unit; and / orcontrolling and / or regulating a temperature of a surface of the metering roller based on a parameter of the coating agent, in particular based on a viscosity and / or a temperature of the coating agent, by the / a control unit.Further details and advantages of the invention will now be explained in more detail on the basis of exemplary embodiments illustrated in the drawings.The following are shown: FIG. 1 shows a schematic illustration of an apparatus according to one embodiment of the invention for melting and applying a coating agent to a surface of a workpiece; FIG. 2 shows a schematic illustration of a metering roller with an inductive temperature control unit according to one embodiment of the invention, and FIG. 3 shows a schematic illustration of a metering roller with an inductive temperature control unit according to a further embodiment of the invention.Identical or functionally equivalent elements are provided with the same reference numerals in all figures.Referring to FIG. 1, a schematic illustration of an apparatus 100 for melting and applying a coating agent 102 to a surface O of a workpiece 104 is illustrated.The coating agent 102 is, in particular, but not by way of limitation, a hot-melt glue.The device 100 further comprises a metering roller 106 and an application roller 108. The metering roller 106 serves for metering and tempering the coating agent 102. The application roller 108 serves in particular for applying, especially for melting, the coating agent 102 on the surface O of the workpiece 104.Furthermore, the metering roller 106 has an inductive temperature control unit 110 explained in more detail in FIGS. 2 and 3. The inductive temperature control unit 110 serves for the temperature control, in particular for heating, of the metering roller 106.In FIG. 1, a smoothing roller 109 is also shown, which is only schematically shown. The smoothing roller 109 is optional and serves for smoothing the melted and applied coating agent 102. The smoothing roller 109 preferably likewise has an inductive temperature control unit 110 of the aforementioned type.For controlling and / or regulating the inductive temperature control unit 110, the device 100 has a control unit 112, which is connected to the inductive temperature control unit 110.During operation of the apparatus 100, the coating agent 102 is supplied to the two rollers 106, 108. Specifically, the coating agent 102 is supplied to a nip formed between the two rollers 106, 108. The metering roller 106 is moved in the clockwise direction, while the application roller 108 is operated in the counterclockwise direction. As a result, a film is applied to the application roller, which is then applied to the workpiece 104 by the application roller. Optionally, a smoothing roller 109 can additionally be provided. This is shown in FIG. 1 and is arranged behind the applicator roller. The smoothing roll is then operated in the clockwise direction and smoothes the applied hot glue. Absorbed material of the hot glue takes the smoothing roller with it and conveys it through the nip between the smoothing roller and the application roller into the region between which the application roller 108 and the smoothing roller 109 form. A doctor blade (shown schematically) takes the material of the hot glue from the smoothing roller 109 at about 10 to 11 o'clock and cleans the smoothing roller for its next revolution until it makes contact with the hot glue on the workpiece 104 at about 6 o'clock.The inductive temperature control unit 110 preferably heats the metering roller 106 to a predetermined temperature. The setting and / or adjustment of the predetermined temperature is preferably carried out by the control unit 112.The heated metering roller 106 heats the coating agent 102 to its melting temperature. The term "melting temperature" in the sense of this application can be understood to mean the temperature that the coating agent 102 must have in order that it can be processed, i.e. melted, reliably and according to its determination. Thus, for example, it can be provided that the coating agent 102 is already "preheated" before being fed into the device 100, for example preheated to half the melting temperature, and the metering roller 106 heats the coating agent 102 further to its melting temperature.Non-limiting examples of melting temperature values are temperatures in the range 100°-200° C.Particularly preferably, the smoothing roller 109 is also heated and has a temperature control unit 110, as described in connection with the metering roller 106.Alternatively, it can be provided that the coating agent 103 is cold and is only brought completely and in particular to its melting temperature by the metering roller 106. The term "cold" in the sense of this application can be understood to mean a temperature which the coating agent 102 has, for example, in a storable state, that is to say a temperature which is significantly below the melting temperature, for example room temperature of about 20° C.The coating agent 102 heated to its melting temperature is then applied, in particular melted, by the application roller 108 onto the surface O of the workpiece 104. This is illustrated in the image plane in the right-hand region of the workpiece 104.As the name already indicates, the inductive temperature control unit 110 is a temperature control unit 100 which heats the metering roller 106 by induction. This advantageously makes it possible to dispense with the disadvantageous heating devices and heating media mentioned in the introduction.A metering roller 106 with an inductive temperature control unit 110 is explained in more detail below with reference to FIG. 2.As can be seen from the longitudinal section through a metering roller 106 shown in FIG. 2, the temperature control unit 110, which is arranged in the interior of the metering roller 106, has three temperature control elements 114. The temperature control elements 114 are arranged circumferentially around the metering roller 106.Furthermore, the metering roller 106 is divided in the axial direction A into a plurality of segments, in the exemplary embodiment according to FIG. 2 into three segments, 107.1, 107.2, 107.3.A temperature control element 114 is arranged in each of the segments 107.1-107-3 in order to temperature control the surface O of the respective segment 107.1-107.3.The temperature control elements 114 are electrically connected to the control unit 112 by cables in the interior of the metering roller 106. The control unit 112 is configured to individually control and / or regulate each of the temperature-control elements 114, i.e. either the same temperature or different temperatures can be set and / or regulated by the control unit 112 for all temperature-control elements 114.FIG. 3 shows a schematic illustration of a further embodiment of a metering roller 106 having an inductive temperature control unit 110.In its basic construction, the metering roller 106 corresponds substantially to the metering roller 106 according to FIG. 2.However, the metering roller 106 according to FIG. 3 has six segments 107.1-107.6 arranged in the axial direction A.The temperature control unit 110 however has six temperature control elements 114. Analogously to the embodiment according to FIG. 2, each segment 107.1-107.6 of the metering roller 106 has a temperature control element 114. Each temperature control element 114 serves for the temperature control of a respective segment 107.1-107.6.Thus, in each of the six segments 107.1-107.6 shown, the same temperature or different temperatures can be set.For this purpose, all temperature control elements 114 are connected to the control unit 112 in a manner analogous to that already described with reference to FIG. 2.In addition, the metering roller 106 has a temperature sensor 116. The temperature sensor 116 is introduced into a channel bore within a wall of the metering roller 106.As can be seen from FIG. 2, the temperature sensor 116 preferably extends over the entire length of the metering roller 106, but at least over the entire length of the segments 107.1-107.6.For example, the temperature sensor 116 has temperature sensors, not shown, wherein a temperature sensor is arranged in one of the segments 107.1-107.6, respectively. This enables a detection of the temperatures within the segments 107.1-107.6.In particular, the temperature sensor 116 detects a jacket temperature of the metering roller 106.Otherwise, the embodiment of a metering roller 106 shown in FIG. 3 corresponds in terms of structure and function to the embodiment shown in FIG. 2, so that reference is made to the above description thereof.In further embodiments (not shown) of the device and / or metering rollers according to the invention, individual or a plurality of features and / or advantages of the aforementioned embodiments can be combined with one another as desired. For example, in the embodiment of a metering roller shown in FIG. 2, a temperature sensor according to the embodiment shown in FIG. 3 can also be provided.List of reference characters100 Device 102 Coating agent 104 Workpiece 106 Metering roller 107 Segment of the metering roller 108 Application roller 109 Smoothing roller 110 Inductive temperature control unit 112 Control unit 114 Temperature control element (inductor) 116 Temperature sensor A Axial direction O Surface

Claims

Device (100) for melting and applying a coating agent (102), in particular a hot glue, to a surface (O) of a workpiece (104), wherein the device (100) comprises: - a metering roller (106) for metering and for tempering the coating agent (102); - an application roller (108) for applying the coating agent (102) to the surface (O) of the workpiece (104); - an inductive tempering unit (110), which is arranged in the interior of the metering roller (106), for inductively tempering at least one segment (107.i) of the metering roller (106); and - a control unit (112) for controlling and / or regulating the inductive tempering unit (110).Device (100) according to claim 1, wherein the metering roller (106) has a plurality of segments (107.1-107.6) arranged in an axial direction (A) and the temperature control unit (110) has a plurality of temperature control elements (114), wherein a temperature control element (114) is arranged in each segment (107.i) for, in particular individually, controlling the temperature of the segments (107.1-107.6).The device (100) according to claim 2, wherein the control unit (112) is connected to each of the temperature control elements (114), for controlling and / or regulating the temperature control elements (114), in particular for individually controlling and / or regulating the temperature control elements (114).The device (100) according to any one of the preceding claims, wherein the control unit (112) is configured to set and / or adjust a uniform temperature along the surface (O) of the metering roller (106) and / or a temperature gradient along the surface (O) of the metering roller (106).The device (100) according to any one of the preceding claims, further comprising: - a temperature sensor (116) for detecting a temperature of the surface (O) of the metering roller (106) and / or of the application roller (108), in particular for detecting a temperature of the surface (O) in each segment (107.i) of the metering roller (106).The device (100) according to claim 5, wherein the control unit (112) is configured to control and / or regulate the inductive temperature control unit (110), in particular each temperature control element (114), based on a signal of the temperature sensor.Device (100) according to one of the preceding claims, wherein the control unit (112) is configured to control and / or regulate the inductive temperature control unit (110), in particular each temperature control element (114), based on a characteristic diagram, in particular based on a current characteristic diagram of the inductive temperature control unit (110).The device (100) according to any one of the preceding claims, wherein the control unit (112) is configured to control and / or regulate the inductive temperature control unit (110), in particular each temperature control element (114), based on a parameter of the coating agent (102), in particular based on a viscosity and / or a temperature of the coating agent (102).The device (100) according to any one of the preceding claims, wherein the inductive temperature control unit (110) has a power in a range between 1.5 kW and 40 kW, in particular between 2 kW and 35 kW, especially between 4 kW and 25 kW, advantageously between 5 kW and 20 kW.The device (100) according to one of the preceding claims, wherein the application roller (108) has a further inductive temperature control unit (110).The device (100) according to one of the preceding claims, further comprising: - a smoothing roller (109) for smoothing the melted and applied coating agent (102), wherein the smoothing roller (109) further comprises a further inductive temperature control unit (110).Method for tempering an inductive tempering unit (110) in a device (100) for applying a coating agent (102), in particular an adhesive, to a surface (O) of a workpiece (104), wherein the inductive tempering unit (110) is arranged in the interior of a metering roller (106); the method comprising the steps: - controlling and / or regulating a temperature of a surface (O) of the metering roller (106) based on a signal of a temperature sensor (116) by a control unit (112); and / or - controlling and / or regulating a temperature of a surface (O) of the metering roller (106) based on a characteristic diagram, in particular based on a current characteristic diagram of the inductive tempering unit (110), by the / a control unit (112); and / or - controlling and / or regulating a temperature of a surface (O) of the metering roller (106) on the basis of a parameter of the coating agent (102), in particular on the basis of a viscosity and / or a temperature of the coating agent (102), by the / a control unit (112).

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