Repair method for a workpiece made of a plastic material, repair device

Description

[0001] The invention relates to a repair method for a workpiece made of a plastic material, wherein an induction heating device is positioned at a repair area of ​​the workpiece, the induction heating device comprises a magnetic field generating device and a heat source, wherein the magnetic field generating device and the heat source are separate components of the induction heating device which can be positioned separately from one another, the heat source is arranged between the magnetic field generating device and the repair area, a repair material is positioned at the repair area, the repair material is heated via the heat source arranged at the repair area, and the heat source is inductively heated by the magnetic field generating device.

[0002] The invention further relates to a repair device on a workpiece made of a plastic material, comprising an induction heating device which is arranged on the workpiece, and a repair material which is arranged on a repair region of the workpiece, wherein the induction heating device comprises a magnetic field generating device and a heat source, the magnetic field generating device and the heat source are separate components of the induction heating device which can be positioned separately from one another, the heat source is arranged between the magnetic field generating device and the repair region, and the repair device has at least one temperature sensor.

[0003] DE 20 2015 100 080 U1 discloses an induction heating device comprising a carrier and a coil device arranged on the carrier. The coil device comprises a plurality of spiral windings arranged in rows and columns, wherein the spiral windings are configured such that, when current flows through the spiral windings, the current direction in adjacent edge winding sections of adjacent spiral windings in a row or column is at least approximately the same.

[0004] DE 10 2013 111 266 A1 discloses a coil device comprising at least one current-carrying high-frequency stranded wire and a carrier for the at least one high-frequency stranded wire. The at least one carrier is a mesh network, and the at least one high-frequency stranded wire is held by one or more holding threads that rest against the at least one high-frequency stranded wire and webs of the mesh network.

[0005] A repair device for composite materials is known from US Pat. No. 8,980,029 B1. The repair device comprises a magnetic field generating device and a susceptor. The magnetic field generating device generates a magnetic flux, which inductively heats the susceptor. The magnetic field generating device can be pressed against a repair unit with a repair site by means of compaction pressure.

[0006] DE 42 37 857 C2 discloses a method for the time-clocked determination of manipulated variables acting on a controlled system. In this method, a fictitious input variable for the next following cycle is determined from a primary input variable of the most recent cycle or primary input variables of previous cycles and from a primary input variable of the current cycle. At least the fictitious input variable is taken into account to determine the manipulated variable according to fuzzy logic.

[0007] DE 197 31 258 A1 discloses a method for measuring the temperature of an inductively heated element. The heated element has a secondary heating coil, by means of which induction currents that heat the element are generated by a current-carrying primary winding. The primary winding is intermittently connected to a power source to control or regulate the temperature of the element. The temperature of the heated element is detected by a temperature sensor, and the temperature is measured during pauses in the primary winding's current flow.

[0008] EP 1 732 357 A2 discloses a heating device for an induction cooking appliance. The heating device comprises an inductor for heating a heating element of a cooking container and a control unit configured to monitor the heating element for reaching a cooking temperature. Monitoring is performed by adjusting the frequency of the alternating current flowing through the inductor and detecting at least one electrical variable as a function of time.

[0009] An induction cooking appliance with an IR sensor is known from DE 10 2013 201 681 A1.

[0010] From GB 2 192 294 A a method for inductively heating an end region of an elongated workpiece is known.

[0011] US 2011 / 0139769 A1 discloses an induction heating device comprising a heating mat, a magnetic field generating device, and a heat source. The magnetic field generating device and heat source are integrated into the structural material of the heating mat.

[0012] From EP 2 796 265 A1 a repair device for a workpiece made of a fiber composite material is known, comprising an induction heating device and a repair material which is arranged on the workpiece and which is heated by means of the induction heating device.

[0013] From US 2012 / 145703 A1, a device for curing a composite part is known, comprising a tool with a tool surface which can be placed against a first side of the part, a first inductive heating circuit for heating the tool surface, a heating blanket which can be arranged over a second side of the part, a second inductive heating circuit in the heating blanket for heating the blanket and an electronic power supply which is coupled to the first and the second inductive heating circuit.

[0014] US 2015 / 001768 A1 discloses a method for repairing damage to a damaged zone formed on a thermoplastic film component. In this method, the thermoplastic film is heated directly by dielectric heating.

[0015] From US 2008 / 175753 A1 a device for treating objects is known, comprising a chamber configured to hold an object to be treated, wherein a magnetically sensitive microwire sensor element is connected to the object and operable to detect a parameter relating to the temperature of the object during its treatment, and a detector having an antenna arrangement in the vicinity of the chamber, which generates an alternating magnetic field in the region of the sensor and detects a magnetic response of the sensor as a measure of the parameter.

[0016] DE 10 2016 209 487 A1 discloses an induction heating device comprising at least one coil layer with a coil device and a carrier on which the coil device is arranged. The at least one coil layer is designed to be flexible. The at least one coil layer is embedded in the structural material of a vacuum hood, and the vacuum hood, together with the at least one coil layer, is designed to be flexible.

[0017] DE 10 2011 076 463 A1 discloses a repair method according to the preamble of claim 1 and a repair device according to the preamble of claim 13.

[0018] The invention is based on the object of providing a repair method of the type mentioned above which is easy to carry out and can be used flexibly.

[0019] This object is achieved according to the invention in the repair method mentioned at the outset in that a temperature is measured by which a heat exposure of the repair material by the heat source is characterized, that the temperature is controlled and / or regulated by means of a control and / or regulating device, that the control and / or regulation of the temperature is carried out by the control and / or regulating device according to a temperature profile specification, and that the temperature profile specification has a heating area and a working area adjoining the heating area.

[0020] The workpiece, for example, is a fiber composite component. It exhibits damage in the repair area.

[0021] To perform the repair process, the heat source is placed at the repair area and inductively heated by the magnetic field generating device. The heat source, in turn, heats the repair material placed at the repair area of ​​the workpiece.

[0022] The heat source is positioned between the magnetic field generation device and the repair area. The magnetic field generation device and heat source are separate components of the induction heating device, which can be positioned independently of each other. This allows the heat source to be individually adapted to the surface of the repair area. The heat source can be positioned directly on the surface of the repair area, thereby achieving improved heat transfer to the repair area of ​​the workpiece.

[0023] The magnetic field generating device and the heat source are separated from each other by material. This allows the heat source to be shielded, for example, by a thermal insulation layer. This allows for particularly flexible and efficient use of the induction heating device for repairs.

[0024] The control and / or regulating device controls and / or regulates the temperature, which characterizes the heat applied to the repair material by the heat source. In this way, the temperature of the repair material can be controlled and / or regulated.

[0025] The repair material can be, for example, a thermoplastic or a thermosetting material. Depending on the repair material used, a different temperature profile is required for the repair process.

[0026] By controlling and / or regulating the temperature using the control and / or regulating device according to the temperature profile specification, the repair process can be easily carried out using different repair materials. This enables flexible use of the repair process.

[0027] The temperature profile specification includes a heating zone and a working zone adjacent to the heating zone. For example, to carry out the repair process with the thermosetting repair material, a defined temperature profile over time is required within the heating zone. A desired chemical change in the repair material takes place within the working zone.

[0028] In particular, the magnetic field generating device is subjected to an electric current, wherein the electric current and / or an electric voltage and / or electric power resulting from the current application is a control variable. This allows the temperature of the repair material to be easily controlled and / or regulated.

[0029] It is advantageous if the electrical current and / or the electrical voltage and / or the electrical power is controlled by the control and / or regulating device in such a way that a temporal profile of an effective value of the electrical current and / or an effective value of the electrical voltage and / or an effective value of the electrical power corresponds at least approximately to a temporal profile of the temperature. This enables simple control of the current application by the control and / or regulating device if the current applied to the magnetic field generating device is, for example, an alternating current. This enables more precise control of the temperature by the control and / or regulating device.

[0030] It is advantageous if the current supply to the magnetic field generating device is deactivated during control pauses, and if the temperature is controlled according to the temperature profile specification by deactivating the current supply during the control pauses. This allows the temperature to be easily controlled and / or regulated by the control and / or regulating device.

[0031] In particular, during operation of the induction heating device, the temperature is measured by at least one temperature sensor, and the measured temperature is transmitted to the control and / or regulating device. This allows for a simple measurement of the temperature near the repair material. The temperature can then be easily regulated by the control and / or regulating device.

[0032] In particular, the temperature profile within the working area is at least approximately constant. The desired chemical change in the repair material occurs within the working area. This allows, for example, the desired chemical change in the thermoplastic or thermosetting repair material to be easily implemented.

[0033] In particular, in the case of a thermoplastic repair material, the temperature profile within the heating range increases monotonically and, in particular, exhibits a constant gradient. The repair process can then be carried out easily for the thermoplastic repair material. The monotonically increasing temperature profile allows the working range to be reached quickly and easily.

[0034] In particular, in the case of a thermosetting repair material, the temperature profile within the heating range increases monotonically in certain sections and, in particular, exhibits a constant gradient in certain sections. This allows the repair process to be carried out easily in the case of the thermosetting repair material. The working area can then be reached easily and quickly.

[0035] It is advantageous, in the case of a thermosetting repair material, if the temperature profile within the heating range has a plateau region in which the temperature profile is at least approximately constant, and especially if volatile components of the thermosetting repair material are evaporated within the plateau region. In the case of the thermosetting repair material, the plateau region is necessary to evaporate volatile components, such as solvents. This allows the desired chemical change of the thermosetting repair material to occur within the working range. In this way, the repair process can be carried out with the thermosetting repair material.

[0036] In particular, in the case of a thermosetting repair material, the temperature profile specification within the heating range exhibits an increase from an initial temperature, with the increase being followed by a plateau region in which the temperature profile specification is at least approximately constant, and with the plateau region being followed by a further increase. This allows the repair process to be carried out easily with the thermosetting repair material.

[0037] In one embodiment, the temperature profile specification includes a cooling zone adjacent to the working area. Within the cooling zone, the temperature profile specification is, in particular, monotonically decreasing and, in particular, has a constant gradient. This enables simple and defined cooling of the repair material. This can, for example, reduce the cooling rate of the repair material if the heat applied to the repair material by the heat source is weakly active.

[0038] It is advantageous if a negative pressure zone is created between a vacuum hood of the induction heating device and the workpiece, in particular if a pressure within the negative pressure zone is measured, and in particular if the pressure is controlled and / or regulated by means of the control and / or regulating device. The vacuum hood is pressed against the workpiece by the negative pressure zone. The vacuum hood can thus be easily positioned on the workpiece. By measuring the pressure within the negative pressure zone, the pressure within the negative pressure zone can be easily controlled and / or regulated using the control and / or regulating device.

[0039] In particular, the pumping power of the vacuum application device is a control variable, with the pumping power being controlled by the control and / or regulating device. This allows the pressure within the vacuum range to be easily controlled and / or regulated by the control and / or regulating device.

[0040] In particular, during operation of the induction heating device, the pressure is measured by at least one pressure sensor, and the measured pressure is transmitted to the control and / or regulating device. The at least one pressure sensor allows the pressure within the negative pressure range to be easily measured. This allows the pressure to be easily regulated by the control and / or regulating device.

[0041] In particular, the control and / or regulation of the pressure by the control and / or regulation device is carried out according to a specified working pressure or a specified working pressure range. This allows the pressure within the vacuum range to be specified according to the repair procedure to be performed. This enables flexible use of the repair procedure.

[0042] In particular, a constant distance is maintained between the magnetic field generating device and the heat source. This constant distance allows the heat source to be heated evenly by means of a homogeneous magnetic field generated by the magnetic field generating device. This also enables homogeneous heating of the repair material.

[0043] In particular, current application to the magnetic field generating device is deactivated for a pause period, during which the temperature and / or pressure is measured. The measured temperature and / or pressure are transmitted to the control and / or regulating device within the pause period. During operation of the induction heating device, the magnetic field generating device generates a time-varying electromagnetic field, which causes interference currents that are induced, for example, in a temperature sensor and / or a pressure sensor and in their lines. During the pause period, a low-interference measurement of the temperature and / or pressure can be carried out. The measured temperature and / or pressure can then be transmitted to the control and / or regulating device within the pause period with low interference.

[0044] In particular, the voltage application is deactivated at a specific clock frequency, and the temperature and / or pressure are measured at this clock frequency. This allows for a simple, low-interference measurement of the temperature and / or pressure at regular intervals.

[0045] It is advantageous to measure the temperature and / or pressure with an initial delay after the start of the pause period. During this delay, any interference currents that may still be present at the beginning of the pause period can decay. This can further improve the accuracy of the temperature and / or pressure measurement.

[0046] In particular, a temperature and / or pressure measurement is completed before the end of the pause time, delayed by a second waiting time. The measured temperature and / or pressure can thus be transmitted to the control and / or regulating device with minimal interference.

[0047] In particular, the repair material is applied in a solid form to the repair area. This allows the repair material to be easily processed and adapted to the geometry of the repair area. The repair material can then be applied in layers to the repair area.

[0048] In one variant of the method, a thermal insulation layer is placed between the magnetic field generating device and the heat source. This improves the thermal shielding of the heat source. This can, for example, reduce heat radiation via a side of the heat source facing away from the workpiece during operation of the induction heating device. This increases the efficiency and effectiveness of the repair process using the induction heating device.

[0049] According to the invention, the repair device mentioned at the outset is provided with at least one temperature sensor measuring a temperature which characterizes the heat applied to the repair material by the heat source, with at least one temperature sensor being connected to a control and / or regulating device in a signal-effective manner, with the control and / or regulating device having a memory device in which a temperature profile specification is stored, and with the control and / or regulating device controlling and / or regulating the temperature measured by the at least one temperature sensor in accordance with the stored temperature profile specification. The repair device according to the invention already has the advantages explained in connection with the method according to the invention.

[0050] Further advantageous embodiments of the repair device according to the invention have already been explained in connection with the repair method according to the invention.

[0051] In particular, the induction heating device, comprising the vacuum hood, the magnetic field generating device, and the heat source, is designed to be flexible. The repair device can then be used on workpieces with a curved surface.

[0052] In one embodiment, a thermal insulation layer is arranged between the magnetic field generating device and the heat source. This increases the efficiency of the induction heating device.

[0053] In particular, the repair method according to the invention can be carried out or is carried out with the repair device according to the invention.

[0054] In particular, the repair method according to the invention can be carried out with the repair device according to the invention or is carried out with it.

[0055] The following description of preferred embodiments, in conjunction with the drawings, serves to explain the invention in more detail.

[0056] They show: Figure 1 shows a schematic representation of an embodiment of a repair device; Figure 2 shows a sectional view of a workpiece on which an embodiment of a repair device is arranged; Figure 3 shows a predetermined temporal profile of a temperature, by which a heat application to a repair material is characterized; Figure 4 shows a temporal profile of an effective value of a current to which a magnetic field generating device is applied; Figure 5 shows a schematic representation of a temporal profile of an embodiment of an interruption of the current at the magnetic field generating device; Figure 6 shows a schematic representation of a temporal profile of a further embodiment of an interruption of the current at the magnetic field generating device; Figure 7 shows a schematic representation of a temporal profile of a further embodiment of an interruption of the current at the magnetic field generating device.and Figure 8 shows a schematic representation of a portion of another embodiment of a repair device. ;

[0057] An embodiment of a repair device which is shown in Figure 1 shown schematically and designated there by 10, comprises a workpiece 12 as the repair object.

[0058] The workpiece 12 is made of a plastic material. It is, for example, a fiber composite component. The workpiece 12 has a repair area 14 with a damage. A repair material 16 is arranged on the repair area 14.

[0059] The repair material 16 has a solid form. Alternatively, it can also be viscous with a large time constant.

[0060] The repair material 16 comprises in particular a repair resin.

[0061] The repair material 16 is in individual layers 17 ( Figure 2 ) at the repair area 14.

[0062] The repair device 10 comprises an induction heating device 18. The induction heating device 18 has a magnetic field generating device 20 and a heat source 22. The heat source 22 is arranged between the magnetic field generating device 20 and the workpiece 12.

[0063] The magnetic field generating device 20 serves to generate a homogeneous electromagnetic field 24 (indicated by arrows), which is inductively converted into heat 26 (indicated by arrows) by the heat source 22. The heat 26 is applied to the repair material 16.

[0064] Magnetic field generating device 20 and heat source 22 are separate components of the induction heating device 18. Magnetic field generating device 20 and heat source 22 can therefore be positioned separately from one another.

[0065] The magnetic field generating device 20 is electrically connected to an induction generator 28 via lines 30a, 30b. The induction generator 28 generates a high-frequency alternating electrical current, which is applied to the magnetic field generating device 20. The frequency is at least 20 kHz and is typically approximately 150 kHz.

[0066] The induction generator 28 is connected to a control and / or regulating device 34 via a line 32. The control and / or regulating device 34 controls the alternating current supplied to the magnetic field generating device 20 by the induction generator 28. For example, it controls an effective value i of the alternating current.

[0067] The control and / or regulating device 34 comprises a memory device 35 in which a temperature profile specification 35' ( Figure 3 ) is stored for a temperature T.

[0068] The effective value i of the alternating current applied to the magnetic field generating device 20 is a control variable for regulating the temperature T by the control and / or regulating device 34. The temperature T characterizes the heat applied to the repair material 16 by the heat source 22.

[0069] At least one temperature sensor 36, which measures the temperature T, is arranged in a region of the heat source 22. The temperature sensor 36 is connected to the control and / or regulating device 34 via a line 38. In this way, the temperature T measured by the temperature sensor 36 is transmitted to the control and / or regulating device 34.

[0070] The temperature T measured by the temperature sensor 36 is an actual temperature. The temperature T is a controlled variable, which is regulated by the control and / or regulating device 34. For this purpose, the control device controls the effective value i, which is a controlled variable. In this way, the temperature T can be controlled according to the temperature profile specification 35' (setpoint temperature).

[0071] Alternatively, it can be provided that an effective value of an alternating electrical voltage or an effective value of an electrical power, which results from the alternating current application to the magnetic field generating device 20, is a control variable for the regulation of the temperature T. The control and / or regulating device 34 then controls the effective value of the alternating electrical voltage or the effective value of the electrical power.

[0072] It can be provided that a negative pressure area 40 is formed between a vacuum hood 42 ( Figure 2) of the induction heating device 18 and the workpiece 12. For this purpose, a vacuum is applied to the vacuum region 40 by a vacuum application device 44. The vacuum application device 44 is, for example, a vacuum pump. It is fluidly connected to the vacuum region 40 via a line 46.

[0073] The vacuum application device 44 is in turn connected to the control and / or regulating device 34 via a line 48. The control and / or regulating device 34 controls, for example, a pumping output of the vacuum application device 44.

[0074] The pump power is a control variable for regulating a pressure P within the negative pressure range 40 by the control and / or regulating device 34.

[0075] The control and / or regulating device 34 is connected to a pressure sensor 52 via a line 50. The pressure sensor 52 is arranged within the vacuum region 40 and measures the pressure P there. The pressure P measured by the pressure sensor 52 is transmitted to the control and / or regulating device 34 via the line 50.

[0076] The pressure P measured by the pressure sensor 52 is an actual pressure. The control and / or regulating device 34 regulates the pressure P within the negative pressure range 40. The pressure P is a controlled variable.

[0077] To regulate the pressure P, the control and / or regulating device 34 controls the pumping power of the vacuum application device 44, which is a control variable. In this way, the pressure P can be regulated according to a predetermined target pressure.

[0078] The control and / or regulating device 34 uses, for example, a PID control or a fuzzy logic to adjust a measured actual value of a variable to a predetermined target value.

[0079] The vacuum region 40 creates a constant distance between the magnetic field generating device 20 and the heat source 22. Furthermore, a constant distance is created between the heat source 22 and the workpiece 12.

[0080] In the Figure 2 In the embodiment shown, the vacuum hood 42 is positioned on the workpiece 12. The heat source 22 is arranged between the repair material 16 at the repair area 14 and the vacuum hood 42. This is a loose component of the induction heating device 18.

[0081] The magnetic field generating device 20 of the induction heating device 18 comprises a coil device 54 with a carrier 56. The coil device 54 is embedded in a structural material 58 of the vacuum hood 42.

[0082] The coil device 54 is designed to be flexible in its entirety with the vacuum hood 42.

[0083] The carrier 56 is made of an electrically insulating material. It is, for example, a fiber structure or a textile structure, such as a woven or knitted fabric.

[0084] A current-carrying high-frequency strand 60 is arranged on the carrier 56.

[0085] The high-frequency stranded wire 60 is used to carry a high-frequency alternating current. It is a bundle of individual wires, each of which is electrically insulated from each other.

[0086] During operation of the induction heating device 18, the individual wires of the wire bundle of the high-frequency stranded wire 60 are electrically connected to the induction generator 28 via the lines 30a, 30b. For this purpose, the high-frequency stranded wire 60 has corresponding terminals 62a, 62b, which are arranged in an outer region of the vacuum hood 42.

[0087] The coil device 54 is designed such that a homogeneous field distribution of the electromagnetic field 24 is achieved over a surface of the coil device 54.

[0088] For further details regarding the design of the coil device 54 and the high-frequency stranded wire 60, reference is made to DE 10 2013 111 266 A1 and DE 20 2015 100 080 U1 of the same applicant. Express and full reference is made to these documents.

[0089] The structural material 58 of the vacuum hood 42 is particularly flexible. It is particularly gas-tight and / or electrically insulating. The structural material 58 is, for example, a silicone material.

[0090] The vacuum hood 42 comprises a channel device 64 with a supply channel 66 which runs from an upper side 68 to a lower side 70 of the vacuum hood 42.

[0091] The supply channel 66 opens into a distributor 72 at the bottom 70. Channels are fluidly connected to the distributor 72, wherein the channels run in particular along the bottom 70 and / or are open toward the bottom 70.

[0092] A connection 74 is arranged at the junction of the supply channel 66 with the upper side 68. The connection 74 is fluidly connected to the vacuum application device 44 via the line 46. In this way, the vacuum region 40 can be created between a side 76 of the workpiece 12 and the underside 70 of the vacuum hood 42.

[0093] The heat source 22 is positioned at a distance from the coil device 54 and is electrically separated from it via the structural material 58.

[0094] The heat source 22 is electrically conductive and, in particular, flexible. It is, for example, a thin metal sheet or metal mesh.

[0095] The heat source 22 is heated homogeneously by means of the homogeneous electromagnetic field 24 generated by the magnetic field generating device 20.

[0096] The temperature sensor 36 is positioned on the underside 70 of the vacuum hood 42. The temperature sensor 36 can be at least partially embedded in the structural material 58 of the vacuum hood 42. The line 38, which is in signal-effective contact with the temperature sensor 36, is led outward, in particular, through the structural material 58 of the vacuum hood 42.

[0097] The pressure sensor 52 is arranged within the vacuum region 40. Similar to the temperature sensor 36, it is arranged on the underside 70 of the vacuum hood 42. The line 50, which is connected to the pressure sensor 52 for signal transmission, is routed to the outside, in particular, via the structural material 58 of the vacuum hood 42.

[0098] For further details of the induction heating device 18 and the vacuum hood 42, reference is made to the unpublished German patent application No. 10 2016 209 487.4 of May 31, 2016, filed by the same applicant. Express and full reference is made to this application.

[0099] A further embodiment of a repair device 10', of which Figure 8 a partial area is shown, comprises at least one thermal insulation layer 80. The repair device 10' is fundamentally similar in design and has fundamentally the same functionality as the repair device 10 described above. Components of the repair device 10' that are identical to components of the repair device 10 are designated below with the same reference numerals. The above description continues to apply to these components.

[0100] The thermal insulation layer 80 is positioned between the magnetic field generating device 20 and the heat source 22. The thermal insulation layer 80 is arranged, for example, between the underside 70 of the vacuum hood 42 and a side 82 of the heat source 22 facing the underside 70.

[0101] The thermal insulation layer 80 is in particular flat. The thermal insulation layer 80 has a first side 84 and a second side 86 opposite the first side 84. In the embodiment according to Figure 8 The first side 84 faces the underside 70 of the vacuum hood 42. In the embodiment shown, the second side 86 faces the side 82 of the heat source 22.

[0102] The first side 84 and / or the second side 86 are in particular planar.

[0103] In particular, the first side 84 of the thermal insulation layer 80 contacts the underside 70 of the vacuum hood 42. The second side 86 contacts in particular the side 82 of the heat source 22.

[0104] The heat source 22 is arranged between the second side 86 and the side 76 of the workpiece 12 which faces the underside 70 of the vacuum hood 42.

[0105] A side 88 of the heat source 22 opposite side 82 faces side 76 of the workpiece 12. The side 88 of the heat source 22 specifically contacts the side 76 of the workpiece 12. The side 82 of the heat source 22 specifically contacts the second side 86 of the thermal insulation layer 80.

[0106] The thermal insulation layer 80 is made of an electrical insulating material. The material from which the thermal insulation layer 80 is made has low thermal conductivity. For example, the material has a lower thermal conductivity than the structural material 58 of the vacuum hood 42. The thermal insulation layer 80 is made, for example, of a heat-insulating plastic.

[0107] During operation of the repair device 10', the thermal insulation layer 80 can reduce heat radiation from the heat source 22 toward the upper side 68 of the vacuum hood 42. This increases the efficiency of the induction heating device 18 and the repair device 10'.

[0108] A repair method using the repair device 10 works as follows: First, the workpiece 12 is provided with the repair material 16 at the repair area 14. For this purpose, the repair material is cut, for example, in a solid form and arranged in layers 17 at the repair area 14. The repair material 16 can later bond to a structural material of the workpiece 12 through heating. This allows the damage to the repair area 14 of the workpiece 12 to be repaired.

[0109] In a next step, the heat source 22 is positioned on side 76 of the workpiece 12 above the repair area 14. The vacuum hood 42 is placed with its underside 70 over the heat source 22 so that the coil assembly 54 is located above the heat source 22. The boundaries of the underside 70 of the vacuum hood 42 extend beyond the boundaries of the heat source 22.

[0110] The heat source 22 is arranged, for example, separately from the vacuum hood 42 on the workpiece 12. The vacuum hood 42 is then positioned on the heat source 22. In this way, the heat source 22 can be arranged, in particular, between the underside 70 of the vacuum hood 42 and the side 76 of the workpiece 12.

[0111] In the case of the repair device 10', which has the additional thermal insulation layer 80, in particular, the heat source 22 is first arranged on the side 76 of the workpiece 12. The thermal insulation layer 80 is then arranged, for example, with its second side 86 on the side 88 of the heat source 22 facing away from the workpiece 12. The vacuum hood 42 is then arranged on the thermal insulation layer 80 so that, for example, the underside 70 of the vacuum hood 42 faces the first side 84 of the thermal insulation layer 80. In this way, the thermal insulation layer 80 is positioned, for example, between the underside 70 of the vacuum hood 42 and the side 82 of the heat source 22.

[0112] By means of the vacuum application device 44, the vacuum region 40 is created between the vacuum hood 42 and the workpiece 12. Due to the vacuum region 40, the underside 70 of the vacuum hood 42 is pressed against the side 76 of the workpiece 12. The underside 70 is also pressed against the heat source 22, which in turn is pressed against the side 76 of the workpiece 12. In this way, a constant distance is created between the magnetic field generation device 20 and the heat source 22. Furthermore, a constant distance is created between the heat source 22 and the layers 17 of the repair material 16.

[0113] The induction generator 28 generates an alternating electrical current, which is applied to the coil device 54 of the magnetic field generating device 20. The alternating current at the coil device 54 creates a homogeneous alternating electromagnetic field 24. Due to this homogeneous alternating electromagnetic field 24, currents are induced in the heat source 22, causing it to heat up homogeneously. The heat source 22, in turn, heats the repair material 16, which is arranged below the heat source 22.

[0114] Due to the constant distance between the magnetic field generating device 20 and the heat source 22, the heat source 22 is heated homogeneously. This, in turn, heats the layers 17 of the repair material 16 homogeneously.

[0115] The flexible design of the induction heating device 18 with the heat source 22 enables homogeneous heating of the layers 17 of the repair material 16 even if the repair area 14 and / or the side 76 has a curved surface.

[0116] The pressure sensor 52 measures the pressure P (actual pressure) within the vacuum range 40. The measured pressure P is transmitted to the control and / or regulating device 34. The control and / or regulating device 34 regulates the pressure P within the vacuum range 40.

[0117] The target pressure according to which the pressure P is regulated by the control and / or regulating device 34 within the vacuum range 40 can be specified on the control and / or regulating device 34. For this purpose, the control and / or regulating device 34 controls, for example, the pumping power of the vacuum application device 44.

[0118] The specified target pressure corresponds, for example, to a working pressure required for the repair process.

[0119] The temperature sensor 36 measures the temperature T (actual temperature). The measured temperature T is transmitted to the control and / or regulating device 34. The control and / or regulating device 34 regulates the temperature T, which characterizes the heat applied to the repair material 16 by the heat source 22.

[0120] The target temperature to which the temperature T is adjusted by the control and / or regulating device 34 can be specified on the control and / or regulating device 34.

[0121] For this purpose, the control and / or regulating device 34 controls the effective value i of the alternating current with which the coil device 54 of the magnetic field generating device 20 is applied.

[0122] It is provided that the temperature profile specification 35' for the target temperature is stored on the control and / or regulating device 34, according to which the temperature T is regulated by the control and / or regulating device 34.

[0123] A change in the effective value i of the alternating current by the control and / or regulating device 34 causes a change in the inductive heating of the heat source 22. For example, an increase in the effective value i leads to stronger inductive heating and a decrease in the effective value i leads to weaker inductive heating of the heat source 22.

[0124] A change in the effective value i by the control and / or regulating device 34 leads at least approximately to an instantaneous change in a temperature of the heat source 22.

[0125] The effective value i is controlled by the control and / or regulating device 34 such that a temporal progression of the effective value i at least approximately corresponds to the temporal progression of the measured temperature T. For this purpose, a sufficiently slow adjustment of the effective value i to the temperature progression specification 35' takes place.

[0126] Alternatively or additionally, it can be provided that the current application to the magnetic field generating device 20 is deactivated by the control and / or regulating device 34 for control pause times. The temperature T is then controlled according to the temperature profile specification 35' by deactivating the current application during the control pause times. The current application is deactivated, in particular, with sufficiently short control pause times and, in particular, with a sufficiently high clock frequency, so that precise control of the temperature T according to the temperature profile specification 35' is enabled by the control and / or regulating device 34.

[0127] In this way, a temporal temperature profile for the temperature T can be specified according to the temperature profile specification 35' for the repair process depending on the repair material 16 used.

[0128] The temperature profile preset 35' has a heating zone 77a and a working zone 77b adjacent to the heating zone 77a. The working zone 77b is followed by a cooling zone 77c. The desired chemical change of the repair material 16 used takes place within the working zone 77b.

[0129] The repair material 16 is, for example, a thermoplastic repair material 16 that is deformable at a specific working temperature. In this case, a temperature profile specification 35' is specified, which, within the heating range 77a, starting from an initial temperature (e.g., room temperature), exhibits at least approximately a linear increase until the working temperature is reached. Within the working range 77b, the specified temperature profile is constant over time and corresponds to the working temperature. Depending on the specification of the thermoplastic repair material 16, the working range 77b has a duration of several minutes to several hours. Subsequently, the repair material 16 is cooled to the initial temperature within the cooling range 77c.

[0130] Alternatively, a thermosetting repair material 16 can be used as the repair material 16. With a thermosetting repair material 16, a chemical transformation occurs depending on a specific temperature profile over time. To carry out the repair process with the thermosetting repair material, it is necessary that the temperature profile specification 35' exhibits a specific increase within the heating region 77a.

[0131] An example of such a temperature profile specification 35' for the temperature T as a function of time is shown schematically in Figure 3 shown.

[0132] The temperature profile specification 35' has a first range I in which the temperature T is monotonically increasing. The temperature T has a constant gradient in the first range I.

[0133] In a second region II following the first region I, the temperature profile specification 35' has a plateau region in which the temperature T remains constant over time. For the duration of the plateau region, volatile components of the thermosetting repair material 16 are evaporated. This is necessary to later carry out the desired chemical modification of the thermosetting repair material.

[0134] The second region II is followed by a third region III, in which the temperature T increases monotonically as a function of time, analogous to region I, until the temperature of the working region 77b is reached.

[0135] Areas I to III correspond to the heating area 77a of the temperature profile specification 35'. A fourth area IV following the third area III corresponds to the working area 77b.

[0136] Within the fourth region IV, the temperature profile specification 35' for the temperature T is constant over time. Depending on the specification of the thermosetting repair material 16, the duration of region IV is a few minutes or up to a few hours.

[0137] The fourth region IV is followed by a fifth region V, which corresponds to the cooling region 77c of the temperature profile specification 35'. Within the fifth region V, the repair material 16 is cooled to the initial temperature. In the fifth region V, the temperature T is monotonically decreasing. In particular, the temperature T exhibits a constant gradient in the fifth region V.

[0138] The temperature profile specification 35' is selected within the fifth range V, for example, such that the heat application to the repair material 16 by the heat source 22 is still weakly active. This makes it possible to define a cooling rate for the repair material 16. This allows the cooling rate of the repair material 16 to be reduced, for example, compared to a cooling rate without additional heat application.

[0139] Following the heat application to the repair material 16 according to the temperature profile specification 35', the repair process is completed. For this purpose, in a final step, the components of the induction heating device 18 are deactivated and the vacuum hood 42 and the heat source 22 are removed from the workpiece 12.

[0140] During operation of the induction heating device 18, a time-varying electromagnetic field 24 is generated by the magnetic field generating device 20. This electromagnetic field 24 causes interference currents that are induced in the temperature sensor 36, the pressure sensor 52, and the lines 38 and 50. The interference currents distort the measurement of the temperature T by the temperature sensor 36 and the pressure P by the pressure sensor 52.

[0141] To enable low-interference acquisition of measured values ​​by sensors within the electromagnetic field 24, it can be provided that the application of alternating current to the magnetic field generating device 20 is deactivated for a pause time Z1 while a measurement is being performed. This deactivation of the current application leads to a decay of the electromagnetic field 24 and also to a decay of the interference currents within the pause time Z1.

[0142] The temperature T is measured by the temperature sensor 36 and the pressure P by the pressure sensor 52 during the pause time Z1, when the current supply to the magnetic field generating device 20 is deactivated. In this way, a low-interference measurement of the temperature T and the pressure P can be performed.

[0143] An exemplary time course of the effective value i of the alternating current at the magnetic field generating device 20 is shown in Figure 4 shown schematically as a function of time. The temporal profile has a first region I', in which the effective value i increases. The first region I' is followed by a second region II', in which the effective value i is constant. The first region I' corresponds, at least approximately, to a temporally linear increase in temperature T. The second region II' corresponds, at least approximately, to a temporally constant profile of temperature T.

[0144] The temporal progression of the effective value i exhibits interruptions 78. The duration of these interruptions 78 corresponds to the pause time Z1. Within the pause time Z1, the effective value i is zero. The measurement is performed during the pause time Z1, with the measurement being carried out within the measurement time Zm. The measurement time Zm corresponds at least approximately to the pause time Z1.

[0145] The start of the pause time Z1 corresponds at least approximately to the start of the measuring time Zm. The end of the pause time Z1 corresponds at least approximately to the end of the measuring time Zm.

[0146] After the end of the pause time Z1, the current application to the magnetic field generating device 20 is continued.

[0147] In particular, the pause time Z1 is so short that during the deactivation of the current application the measured temperature T does not change at least approximately.

[0148] For example, the current supply to the magnetic field generating device 20 is deactivated in a time-locked manner at a clock frequency. In this case, the time period between successive interruptions 78 is constant. A measurement of the temperature T and the pressure P is then performed at the respective pause times Z1 of the interruptions 78, time-locked at this clock frequency.

[0149] At the interruption 78, the duration of the pause time Z1 corresponds to that of the measuring time Zm ( Figure 5 ).

[0150] In a further embodiment of an interruption 78', it is provided that the measurement is carried out offset by a first waiting time Z2 after the start of the pause time Z1 ( Figure 6 ). The measuring time Zm then only begins after the first waiting time Z2 has elapsed after the start of the pause time Z1. The pause time Z1 corresponds to the sum of the first waiting time Z2 and the measuring time Zm.

[0151] During the initial waiting period Z2, any interference currents still present at the time of deactivation of the current application can decay. This further improves the accuracy of the measurement.

[0152] In a further embodiment of an interruption 78" ( Figure 7 ), the measurement also takes place after the start of the pause time Z1 after the expiration of the first waiting time Z2. However, the measurement time Zm ends before the end of the pause time Z1, offset by a second waiting time Z3. The pause time Z1 corresponds to the sum of the first waiting time Z2, the measurement time Zm, and the second waiting time Z3.

[0153] In this way, the measurement can be completed before the end of the pause time Z1, offset by the second waiting time Z3. This prevents or at least avoids disruptions in the transmission of measured values ​​to the control and / or regulating device 34. List of reference symbols

[0154] iRMS value TTemperature PPressure Z1Pause time Z2First waiting time Z3Second waiting time ZmMeasuring time IFirst area IISecond area IIIThird area IVFourth area VFifth area I'First area II'Second area 10Repair device 10'Repair device 12Workpiece 14Repair area 16Repair material 17Layer 18Induction heating device 20Magnetic field generation device 22Heat source 24Electromagnetic field 26Heat 28Induction generator 30aLine 30bLine 32Line 34Control and / or regulating device 35Storage device 35'Temperature profile specification 36Temperature sensor 38Line 40Vacuum area 42Vacuum hood 44Vacuum application device 46Line 48Line 50Line 52Pressure sensor 54Coil device 56Carrier 58Structural material 60High-frequency strand 62aConnection 62bConnection 64Channel device 66Feed channel 68Top 70Bottom 72Distributor 74Connection 76Side 77aHeating area 77bWorking area 77cCooling area 78Interruption 78'Interruption78"Interruption 80Thermal insulation layer 82Page 84First page 86Second page 88Page

Claims

1. Repair method for a workpiece (12) made of a plastic material, wherein an induction heating apparatus (18) is positioned at a repair region (14) of the workpiece (12), the induction heating apparatus (18) comprises a magnetic field generating device (20) and a heat source (22), wherein the magnetic field generating device (20) and the heat source (22) are separate components of the induction heating apparatus (18) that are able to be positioned separately from one another, the heat source (22) is arranged between the magnetic field generating device (20) and the repair region (14), a repair material (16) is positioned on the repair region (14), the repair material (16) is heated by way of the heat source (22) arranged at the repair region (14), and the heat source (22) is inductively heated by the magnetic field generating device (20), characterized in that a temperature (T) is measured, by which an application of heat to the repair material (16) by the heat source (22) is characterized, in that the temperature (T) is controlled and / or regulated by means of a controlling and / or regulating device (34), in that the control and / or regulation of the temperature (T) by the controlling and / or regulating device (34) occurs according to a temperature profile specification (35'), and in that the temperature profile specification (35') has a heating region (77a) and a working region (77b) following the heating region (77a).

2. Repair method in accordance with Claim 1, characterized in that an electric current is applied to the magnetic field generating device (20), and in that the electric current and / or an electrical voltage and / or electrical power resulting from the application of current is a control variable, and in particular characterized in that the electric current and / or the electrical voltage and / or the electrical power is controlled by the controlling and / or regulating device (34) in such a way that a time profile of an effective value (i) of the electric current and / or an effective value of the electrical voltage and / or an effective value of the electrical power at least approximately corresponds to a time profile of the temperature (T), and in particular characterized in that the application of current to the magnetic field generating device (20) is deactivated for control pause times, and in that the regulation of the temperature (T) occurs according to the temperature profile specification (35') by deactivating the application of current with the control pause times.

3. Repair method in accordance with any one of the preceding Claims, characterized in that the temperature profile specification (35') is at least approximately constant within the working region (77b).

4. Repair method in accordance with any one of the preceding Claims, characterized in that, in the case of a thermoplastic repair material (16), the temperature profile specification (35') within the heating region (77a) is monotonically increasing and in particular has a constant slope.

5. Repair method in accordance with any one of the preceding Claims, characterized in that, in the case of a thermosetting repair material (16), the temperature profile specification (35') within the heating region (77a) is monotonically increasing in sections and in particular has a constant slope in sections.

6. Repair method in accordance with any one of the preceding Claims, characterized in that, in the case of a thermosetting repair material (16), the temperature profile specification (35') within the heating region (77a) has a plateau region in which the temperature profile specification (35') is at least approximately constant, and in particular in that within the plateau region, volatile components of the thermosetting repair material (16) are vaporized.

7. Repair method in accordance with any one of the preceding Claims, characterized in that, in the case of a thermosetting repair material (16), the temperature profile specification (35') within the heating region (77a) has an increase starting from an initial temperature, in that the increase is followed by a plateau region in which the temperature profile specification (35') is at least approximately constant, and in that the plateau region is followed by a further increase.

8. Repair method in accordance with any one of the preceding Claims, characterized in that the temperature profile specification (35') has a cooling region (77c) following the working region (77b), and in particular in that the temperature profile specification (35') within the cooling region (77c) is monotonically falling and in particular has a constant slope.

9. Repair method in accordance with any one of the preceding Claims, characterized in that a negative pressure region (40) is produced between a vacuum hood (42) of the induction heating apparatus (18) and the workpiece (12), and in particular in that a pressure (P) within the negative pressure region (40) is measured, and in particular in that the pressure (P) is controlled and / or regulated by means of the controlling and / or regulating device (34), and in particular characterized in that the controlling and / or regulation of the pressure (P) by the controlling and / or regulating device (34) occurs according to a predetermined working pressure or a predetermined working pressure range, and in particular characterized in that a constant distance is established between the magnetic field generating device (20) and the heat source (22).

10. Repair method in accordance with any one of the preceding Claims, characterized in that an application of current to the magnetic field generating device (20) is deactivated for a pause time (Z1), and in that within this pause time (Z1), the temperature (T) is measured and / or a pressure (P) is measured, and in that the temperature (T) measured and / or the pressure (P) measured is transmitted to the controlling and / or regulating device (34) within the pause time (Z1), and in particular characterized in that the application of current is deactivated in a clock-timed manner with a clock frequency, and in that the temperature (T) and / or the pressure (P) is measured in a clock-timed manner with said clock frequency, and in particular characterized in that the temperature (T) and / or the pressure (P) is measured temporally offset by a first wait time (Z2) after the beginning of the pause time (Z1), and in particular characterized in that a measurement of the temperature (T) and / or the pressure (P) is completed temporally offset by a second wait time (Z3) before the end of the pause time (Z1).

11. Repair method in accordance with any one of the preceding Claims, characterized in that the repair material (16) is arranged in solid form on the repair region (14).

12. Repair method in accordance with any one of the preceding Claims, characterized in that a thermal insulating layer (80) is arranged between the magnetic field generating device (20) and the heat source (22).

13. Repair apparatus suited to be arranged on a workpiece (12) made of a plastic material, said repair apparatus comprising an induction heating apparatus (18) suited to be arranged on the workpiece (12), and a repair material (16) suited to be arranged on a repair region (14) of the workpiece (12), wherein the induction heating apparatus (18) comprises a magnetic field generating device (20) and a heat source (22), the magnetic field generating device (20) and the heat source (22) are separate components of the induction heating apparatus (18) that are able to be positioned separately from one another, the heat source (22) is arranged between the magnetic field generating device (20) and the repair region (14), and the repair apparatus has at least one temperature sensor (36), characterized in that the at least one temperature sensor (36) measures a temperature (T) by which an application of heat to the repair material (16) by the heat source (22) is characterized, in that the at least one temperature sensor (36) is signal-operatively connected to a controlling and / or regulating device (34), in that the controlling and / or regulating device (34) has a storage device (35) in which a temperature profile specification (35') is stored, and in that the controlling and / or regulating device (34) controls and / or regulates the temperature (T) measured by the at least one temperature sensor (36) according to the stored temperature profile specification (35').

14. Repair apparatus in accordance with Claim 13, characterized in that the induction heating apparatus (18) comprises a vacuum hood (42), and in particular in that the repair apparatus has at least one pressure sensor (52), which is arranged in a negative pressure region (40) between the vacuum hood (42) and the workpiece (12), wherein the at least one pressure sensor (52) is signal-operatively connected to the controlling and / or regulating device (34), which controls and / or regulates the pressure (P) within the negative pressure region (40).

15. Repair apparatus in accordance with either of Claims 13 or 14, characterized in that a thermal insulating layer (80) is arranged between the magnetic field generating device (20) and the heat source (22).