Connection automation device and contact heating device for thermally inductive cohesive connection of flat flexible material layers

Abstract

The invention relates to a contact heating device (10) for thermally inductively cohesively connecting weldable and / or bondable flat flexible material layers to one another, which material layers can be designed as material webs, material strips and / or material sections and are arranged at least partially overlapping one another, the contact heating device has a first connection electrode (11) and a second connection electrode (12); and a heating element (14) coupled between the coupling electrodes (11, 12); wherein the heating element (14) is designed as a directly energized, flat, planar steel sheet blank. The invention also relates to a connection automation device (1), a hand-held appliance (60) and a method (100).

Description

Technical Field

[0001] The present invention relates to a contact heating device for thermally inductively cohesively connecting weldable and / or adhesively bonded flat flexible material layers to one another, the material layers being configured as material webs, material strips, and / or material segments and being arranged at least partially overlapping. The invention also relates to an automatic connecting device and a handheld appliance for thermally inductively cohesively connecting weldable and / or adhesively bonded flat flexible material layers to one another. Background Art

[0002] Systems and automated joining devices for thermally inductively bonding flat, flexible material layers to one another are generally known from the prior art. For example, the Swiss company and the present applicant, Leister Technologies AG, develops and manufactures automated welding devices and machines for welding thermoplastic films, particularly for use on roofs, landfills, tunnels, truck tarpaulins, and shelter systems. Heat can be supplied by means of hot air or via heated wedges.

[0003] Electric heating elements are known and are also used, for example, in welding devices for overlapping plastic webs. The webs are heated, plasticized, or melted at their joint surfaces by the action of temperature achieved by a heating wedge and subsequently bonded together by pressure by a pressure roller. The heating wedge is moved between the webs while the film webs are applied. Conventional welding wedges consist of three-dimensional wedge-shaped blocks, primarily made of metal (due to its good thermal conductivity), and are heated to a temperature above the melting temperature of the plastic web or of an adhesive applied to the plastic web by means of a heating core inserted into the wedge body of the welding wedge.

[0004] EP 2 005 795 B1 discloses an electric heating element, in particular for heating a wedge-film welding device, comprising two electrodes and a heating resistor arranged between the electrodes, whereby application of a voltage to the electrodes causes heat generation over the length of the heating resistor, wherein the heating resistor is made of a corrosion-resistant material and an upper side of the heating resistor and a lower side opposite the upper side meet at an acute angle, wherein the heating resistor is made using an electrically conductive ceramic material.

[0005] According to EP 2 005 795 B1, a heating resistor is designed according to the shape of a three-dimensional heating wedge of a film welding machine, so that it can replace the heating core and heating wedge of a conventional film welding device.

[0006] EP 3 269 534 B1 discloses a joining robot and a method for joining flat, flexible, weldable and / or adhesively bonded material layers to one another in a heat-inductive, cohesive, seam-like manner using electrically controlled contact heating devices in a heated wedge welding process. The material layers are configured as material webs, strips, and / or segments and are arranged at least partially overlapping. The temperature and / or power of a heating wedge, formed from a three-dimensionally wedge-folded sheet metal blank, is regulated as a function of the relative speed between the material layers and the joining robot. This is done so that the thermal energy transferred from the heating wedge to the material layers to be welded remains constant. For this purpose, the relative speed is detected, and the power of the heating wedge is automatically adjusted if the relative speed changes. Summary of the Invention

[0007] Against this background, the present disclosure aims to provide an improved contact heating device, an improved automatic joining device, and / or an improved handheld device for thermally inductively bonding weldable and / or adhesively bonded flat, flexible material layers to one another, the material layers being configured as material webs, material strips, and / or material segments and arranged at least partially overlapping. In particular, improved operability and ease of operation for inexperienced users are desirable. Further improvements in operational safety are also desirable. Furthermore, improvements in efficiency and / or welding speed are desirable.

[0008] According to a first aspect of the present disclosure, a contact heating device is provided for connecting weldable and / or adhesively bonded flat, flexible material layers to one another in a thermally inductive, material-locking manner. The material layers are configured as material webs, material strips, and / or material segments and are arranged at least partially overlapping. The contact heating device comprises a first and a second connecting electrode, and a heating element connected between the two connecting electrodes. The heating element is configured as a flat, planar steel sheet blank to which current is directly supplied. The heating element can be formed from the flat, planar steel sheet blank to which current is directly supplied.

[0009] According to another aspect of the present disclosure, a joining robot for thermally inductively bonding flat, flexible material layers is described, comprising a contact heating device as described within the scope of the present disclosure. Within the scope of the present disclosure, the joining robot is also referred to as a welding robot. The robot can be designed as a mobile device that moves along the joining region. However, the robot can also be designed as a stationary device, with the joining region moving relative to the device.

[0010] According to a further aspect of the disclosure, a handheld device, in particular a battery-operated handheld device, is described for thermally inductively cohesively connecting flat, flexible material layers, which has a contact heating device as described within the scope of the disclosure.

[0011] According to a further aspect of the disclosure, a method is described for thermally inductively bonding flat, flexible material layers using a contact heating device as described within the scope of the disclosure.

[0012] According to another aspect of the present disclosure, a use of a contact heating device is proposed, which is used to connect weldable and / or adhesive flat flexible material layers to each other in a thermally inductive material-locking manner, wherein the material layers are constructed as material webs, material strips and / or material segments and are arranged at least partially overlapping, wherein the contact heating device has the following components: a first connecting electrode and a second connecting electrode; and a heating element connected between the connecting electrodes; wherein the heating element is constructed as a flat, planar steel sheet blank to which current is directly supplied.

[0013] The inventors have recognized that in the prior art, in the field of contact heating devices for thermally inductively bonding weldable and / or adhesively bonded flat, flexible material layers (which are configured as material webs, strips, and / or segments and are arranged at least partially overlapping) to one another, wedge-shaped heating wedges, i.e., 3D solid bodies, are used, in particular with an embedded heating core or a folded wedge-shaped structure. Such wedge-shaped structures from the prior art have high mechanical stability.

[0014] In contrast, a solution according to one aspect of the present invention proposes a different approach, in which the heating element connected between the connecting electrodes is formed from a flat, planar steel sheet blank that is directly energized. Thus, rather than providing a contact heating device in the form of a wedge with the highest possible mechanical stability, the heating element is constructed as a flat, planar steel sheet blank that is directly energized. The use of flat steel sheet results in a high degree of mechanical flexibility in the heating element, which positively influences the thermal contact between the heating element and the weld material, which is crucial for good weld quality. The heating element can thus be designed as a flexible heating element and adapted to the varying contours between the material layers. The advantage of this proposed solution is that thermal contact can be improved in a simple and cost-effective manner. In contrast, conventional heating wedges impose thermal contact through the steepness of the upper and lower surfaces of the wedge. Furthermore, conventional heating wedges require a high level of force when advancing the heating wedge between the material layers.

[0015] A further advantage of the proposed solution may be that, due to the flexibility of the heating element, which is formed from a flat, planar sheet steel blank, not only unevenness can be compensated, but also minor missetting or operating errors. In other words, the contact heating device can be tolerant to errors in the event that the contact heating device or the heating element is not installed in the completely correct orientation. This may also be advantageous in that it is easier to operate, particularly for inexperienced users.

[0016] A further advantage of the proposed solution may be reduced operating costs. Depending on the material of the material layers to be welded or bonded, the heating elements may be subject to corrosion or difficult-to-remove dirt. The proposed solution may have the advantage that the heating elements can be manufactured cost-effectively from flat, planar sheet steel blanks that are directly energized and can be replaced cost-effectively as wearing parts. A further advantage may be that a more durable solution can be provided due to the reduced material usage.

[0017] A further advantage of the proposed solution may be that operational safety can be improved due to the low thermal mass of the heating element. A further advantage may be that the heating element, consisting of a flat, planar steel sheet blank to which current is directly supplied, can offer high efficiency, in particular low power loss during heating and operation. A further advantage may be that rapid temperature regulation and / or high welding speeds can be achieved.

[0018] A further advantage of the proposed solution may be that it provides uniform heat release to the upper material layer on the upper side of the heating element and the lower material layer on the lower side of the heating element. Since the heating element consists of a flat, planar sheet steel blank that is directly energized, there is little or no significant temperature difference between the upper and lower sides of the sheet steel blank. This may also improve the quality of the seam or connection.

[0019] During operation, the first and second connecting electrodes can be connected to a preferably adjustable current and / or voltage source. A heating element is connected between the first and second connecting electrodes. The electrical power is converted directly into thermal power in the sheet steel blank. The sheet steel blank thus serves directly as a heating conductor.

[0020] Within the scope of the present disclosure, a flat, planar sheet steel blank can be understood as a planar sheet metal element, particularly an unbent sheet metal element. Within the scope of the present disclosure, a planar or unbent sheet metal element, in addition to a completely flat sheet metal element, can also be understood as a sheet metal element having a slight curvature, for example, a curvature of no more than 20°, particularly no more than 10°, and particularly no more than 5° relative to the plane of the steel sheet. In particular, a planar sheet metal element can be formed from a single-layer sheet steel blank. In particular, the planar sheet steel blank is not folded and is not designed in a wedge-shaped manner. In this case, the unfolded region of the sheet steel blank, understood as the heating element, can be connected to other regions that form the connecting electrode or part of the connecting electrode. The portion of the sheet steel blank designed to provide at least 70%, particularly at least 80%, and particularly at least 90% of the heating power of the contact heating device can be considered the heating element. The sheet steel blank of the heating element is preferably as thin and mechanically flexible as possible and designed to provide the most uniform thermal contact possible.

[0021] The sheet steel blank of the heating element can have at least one partial cutout in the longitudinal direction. In particular, the sheet steel blank of the heating element can have a flat U-shaped geometry. In this case, a first leg of the sheet steel blank of the heating element can be connected to a first connecting contact on a first side of the partial cutout, and a second leg of the sheet steel blank of the heating element can be connected to a second connecting contact on a second side of the partial cutout.

[0022] The sheet steel blank of the heating element, or the sheet steel blank forming the heating element, can include the following components: a first flat, planar arm connected to a first connecting electrode; a second flat, planar arm connected to a second connecting electrode; wherein the first arm and the second arm lie flatly above or alongside one another in the same plane; and wherein the sheet steel blank of the heating element has a connecting region at the heating element tip that connects the first arm and the second arm to one another. In particular, the first arm, the second arm, and the connecting region can lie in the same plane. The first arm and the second arm can be designed to extend between the material layers along the feed direction of the contact heating device. The connecting region at the heating element tip can extend transversely to the arms and transversely to the feed direction.

[0023] In one refinement, the heating element can be designed to provide an elevated temperature in the connection region compared to the support arms. This solution can have the advantage of providing a heat distribution that is advantageous for welding or bonding purposes. In particular, the connection region can be arranged rearward in the feed direction, so that the material layers to be connected are exposed to the elevated temperature immediately before they come into contact with each other due to the contact heating device. This improves handling, as the material layers are not unnecessarily brought to excessive temperatures prematurely and do not adhere to the contact heating device in a molten or molten state prematurely, for example, during breaks in operation or during initial positioning or repositioning. The inventors have recognized that, unlike conventional bulky heating wedges with a high thermal mass, the proposed solution makes it possible to flexibly provide an advantageous, locally variable heat distribution on the surface of the steel sheet blank of the heating element.

[0024] The heating element can be designed to provide a uniform heat distribution, particularly in the connection region at the rear edge, for example, at the heating element tip. For example, the heating element can be designed to provide a uniform heat distribution across the width of the heating element in the connection region or at the heating element tip. A uniform heat distribution can be understood as meaning that the temperature or the heat released during operation does not vary by more than 40%, particularly by more than 25%, and particularly by more than 15%.

[0025] The connecting region can have a structured portion in the form of a notch (or groove or opening) designed to locally reduce the current cross section compared to an unstructured cross section and thereby locally increase the heating power. In particular, the sheet steel blank of the heating element can have a U-shaped geometry with the structured portion in and adjacent to the connecting region. In other words, the sheet steel blank of the heating element can have a U-shaped geometry and, in the deflection region, a structured portion in the form of a notch that locally reduces the current cross section compared to an unstructured cross section and thereby locally increases the heating power. Within the scope of this disclosure, a notch can also be understood as a groove or opening. The notch does not have to penetrate completely through the sheet steel blank but can also include a deepening in the sheet steel blank. The deepening can also influence the cross section and result in a different current density and, therefore, heating characteristics. The notch can, for example, be formed as a punched or laser-machined groove in the sheet steel blank. The advantage of this solution can be cost-effective production.

[0026] In one refinement, the cutout can be configured as an elongated groove, in particular at an angle to the rear edge of the heating element tip, in particular at an angle between 20° and 80°, in particular between 30° and 60°. The elongated groove can advantageously influence the current distribution. This solution can be advantageous in terms of favorable heat distribution.

[0027] The cutouts can be arranged symmetrically, at least in sections. In particular, the cutouts can be arranged fanning out in a tree-like manner. The tree-like structure of the cutouts can have forks. The advantage of this solution can be improved heat distribution, in particular a more uniform heat distribution provided by the steel sheet blank of the heating element.

[0028] The cutouts can comprise a plurality of parallel slits of different lengths. The advantage of this solution can be its easy manufacturability, wherein the temperature distribution can be easily influenced. Alternatively, slits of equal length or punctiform grooves can also be used. Alternatively or additionally, the distribution or density of the cutouts on the steel sheet blank of the heating element can be adapted to provide a predetermined temperature distribution, in particular a uniform temperature distribution in the heating element tip or connection area. Optionally, at least one of the slits can be connected to a partial cutout located between the arms in the longitudinal direction. This allows the current to be at least partially diverted from the central area to the edge areas, and an improved distribution of the heating power can be achieved.

[0029] The first and / or second connecting electrodes can be formed by an extension of the sheet steel blank. The first and / or second connecting electrodes, or extensions, can extend laterally beyond the heating element, in particular transversely to the feed direction for thermally connecting the material layers. This solution can have the advantage that the contact heating device can be manufactured cost-effectively. Another advantage of this solution can be that the contact heating device can be mechanically fixed and introduced (laterally) between the material layers in an easy manner. The first and second connecting electrodes can be arranged laterally to the heating element and on the same side of the heating element. This allows for easy lateral introduction between the upper and lower material layers.

[0030] In one refinement, the extension of the sheet metal blank can be designed so that the first and / or second connecting electrode is arranged elevated relative to the plane in which the flat, planar sheet metal blank of the heating element is located; in particular, the first and second connecting electrodes can be arranged at different heights. This elevated arrangement ensures a distance from the material layer and provides space for a receptacle for fastening the contact heating device. A further advantage can be a compact design. This arrangement of the first and second connecting electrodes can be advantageous in that incorrect installation can be avoided.

[0031] The sheet steel blank of the heating element can have a thickness between 0.1 mm and 1.5 mm, in particular between 0.5 mm and 1.0 mm, and in particular between 0.7 mm and 0.9 mm. This design can have the advantage of improved material flow through the material layers to be connected, while simultaneously providing sufficient mechanical stability. It can provide good heating power, while the heating element is sufficiently flexible yet not overly sensitive. Another advantage of this design can be that the heating element can be easily inserted between the material layers to be connected. In one refinement, the sheet steel blank has a uniform thickness or material thickness. This simplifies production. Optionally, the heating wedge tip can have a phase. This not only smoothes the mechanical transition between the material layers but also increases the current density in the area of ​​the heating wedge tip.

[0032] The sheet steel blank of the heating element can be mechanically flexible. In particular, it can be designed to compensate for unevenness in the base. Due to the flexibility of the heating element, which is designed as a flat, planar sheet steel blank, these unevennesses can be compensated. This can result in improved joint quality. For example, the sheet steel blank of the heating element can be designed to bend by 20°, particularly 10°, or even 5° in the longitudinal direction. Unlike conventional rigid heating wedges, particularly those consisting of a solid, rigid base into which one or more heating cores are incorporated, it is proposed that the sheet steel blank of the heating element be mechanically flexible. A further advantage of this design may be that the positioning or installation of the heating element in the welding robot is more tolerant. This makes it easier to use, even for untrained users.

[0033] The sheet steel blank of the heating element can have a step-up at the rear end or at the heating wedge tip. For example, a rolled, flattened end can be provided, which can be produced cost-effectively. This can further improve the aggregation of the material layers.

[0034] In addition to the sheet metal blank forming the heating element, a further section of the sheet metal blank, particularly one-piece, can be provided. This further section of the sheet metal blank has a folded edge at its rear end, formed by folding or overlapping the further section of the sheet metal blank. In other words, this further section of the sheet metal blank can be provided, which improves mechanical stability while also being cost-effective to manufacture. A further advantage can be that the fold, which is located transverse to the feed direction and at the front side along the feed direction, provides a rounded front side when connecting the material layers. This improves slippage between the material layers because hard or sharp edges at the tips, which could potentially snag and damage the material layers, can be avoided. Such hard edges, for example, can be produced during cost-effective manufacturing using a punching tool.

[0035] The heating element can be designed for an operating temperature between 200° C. and 700° C., in particular between 300° C. and 600° C. The advantage of this solution can be that a good connection can be provided between the material layers, while at the same time the risk of temperature-induced deformation of the sheet steel blank of the heating element can be avoided or at least reduced.

[0036] The contact heating device can be set for a current between 50 A and 700 A, in particular between 100 A and 500 A. In one application, for example, the contact heating device can be operated as an overlap welding robot at a voltage of 5 V and a current of up to 300 A. In an application for full-surface welding of asphalt webs, a voltage of up to 43 V and a current of up to 300 A can be set, for example.

[0037] The sheet steel blank can include an electrically conductive, high-temperature-resistant and corrosion-resistant alloy, in particular stainless steel. For example, the sheet steel blank can be made of 1.4301 stainless steel. This design can also have the advantage of being able to process material layers made of, for example, PVC. However, unlike the ceramic heating wedges proposed in the prior art, it can also be flexibly adapted to the floor surface.

[0038] Optionally, the contact heating device can include multiple heating elements connected between connecting electrodes. Each of the heating elements can be designed as a flat, planar steel sheet blank to which current is directly supplied. In particular, multiple heating elements can have a common steel sheet blank. This allows the width to be covered by the contact heating device to be increased, for example, for full-surface welding of asphalt webs. Optionally, the contact heating device can also include multiple U-shaped steel sheet blanks connected in series, which can each be optionally rotated 180° relative to one another. An exemplary application is full-surface or edge-side welding of asphalt webs or sections.

[0039] According to another aspect of the present disclosure, a method for determining the temperature or temperature distribution of a contact heating device is proposed, the method comprising the following steps: measuring a voltage drop across a respective heating element; determining a temperature-dependent partial resistance of the respective heating element based on the measured voltage drop; and determining a temperature distribution over the width of the contact heating device based on the partial resistance of the respective heating element.

[0040] The advantages described above in detail for the first aspect of the present invention are also applicable to the other aspects of the present invention.

[0041] It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Exemplary embodiments of the present invention are shown in the following drawings and are explained in more detail in the following description.

[0043] Figure 1 A perspective view of a welding robot with a contact heating device near the bottom is shown;

[0044] Figure 2 An enlarged cutout portion of a perspective view of a contact heating device is shown;

[0045] Figure 3 shows further enlarged details of the perspective view with the contact heating device from different viewing positions;

[0046] Figure 4 shows a perspective view of a contact heating device;

[0047] Figure 5 shows a top view of a contact heating device;

[0048] Figure 6 The heat distribution of a design of a contact heating device is shown;

[0049] Figure 7 shows the heat distribution of another design of the contact heating device;

[0050] Figure 8 A top view showing another design of a contact heating device;

[0051] Figure 9 A further embodiment of a contact heating device is shown, which is particularly used for flat welding of asphalt webs;

[0052] Figure 10A perspective view of a welding robot is shown with the hold-down roller raised;

[0053] Figure 11 Shown from Figure 10 A perspective view of a welding robot with the pressing roller lowered;

[0054] Figure 12 A particularly battery-operated handheld appliance with a contact heating device is shown;

[0055] Figure 13 shows a top view of a contact heating device;

[0056] Figure 14 A flow chart of a method for thermally inductively cohesively connecting flat, flexible material layers using a contact heating device is shown. DETAILED DESCRIPTION

[0057] Figure 1 A schematic perspective view of an exemplary joining robot or welding robot 1 is shown for thermally inductively bonding flat, flexible, weldable and / or adhesively bonded material layers to one another. The material layers are configured as material webs, strips, and / or segments and are arranged at least partially overlapping. Within the scope of this disclosure, joining robots are also referred to as welding robots, and vice versa. The welding robot 1 includes a heating device configured as a contact heating device 10 and a chassis 20 with a guide rod 30.

[0058] Figure 2 and Figure 3 Shown from different observation positions Figure 1 An enlarged detail of a welding robot 1 with a contact heating device 10 is shown.

[0059] The working direction of movement of the welding robot 1 is indicated by reference numeral 31. This direction of movement 31 represents the feed direction along which the welding robot is guided during operation along overlapping material layers or material webs in order to thermally connect the material layers to one another. A contact heating device 10 is introduced into the overlapping region between an upper material layer and a lower material layer (not shown). This allows the contact heating device to heat and, in particular, at least partially plasticize or melt the underside of the upper material layer and the upper side of the lower material layer, or the adhesive applied thereto.

[0060] Thus, during operation, the upper material layer is arranged at least partially in sections on the upper side of the contact heating device 10. The lower material layer is arranged at least partially in sections on the lower side of the contact heating device 10. For the thermal inductive connection, the contact heating device 10 is guided along the overlapping area between the material layers. Figure 1In the example shown in , the lower material layer is located, for example, on the left in feed direction 31, and the upper material layer arranged thereon at least in sections is located on the right in feed direction 31. At least in the region in which the material layers are to be connected, the upper and lower material layers at least partially overlap.

[0061] The chassis 20 also has a pressure roller 21, which is designed to apply pressure to the material web in the working direction behind the contact heating device 10. The pressure roller 21 can also be implemented as a drive roller, which automatically drives the welding robot 1. Figure 3 As shown, the pressure roller 21 can be driven by a belt drive 24. The drive motor for the belt drive 24 can be arranged in a protected manner in the housing of the chassis 20. Alternatively, an optional independent drive roller can also be provided. In the embodiment shown, the chassis 20 also has further pulleys 22 and 23. It goes without saying that other designs of the chassis 20 and other arrangements of the contact heating device 10 at the chassis 20 are conceivable. For example, the contact heating device can be arranged not at the front side in the feed direction 31, but at the rear side of the chassis 20 or between the front pulleys 22, 23 and the subsequent pressure roller 21 in the feed direction 31. However, Figures 1 to 3 An advantage of the arrangement shown in is that a user can easily control and monitor the correct positioning and guidance of the contact heating device 10 between the material layers.

[0062] Figures 1 to 3 The welding robot 1 shown in FIG is designed as a bottom-mounted welding robot. A bottom-mounted welding robot uses a pressure roller 21 on one side to press against the melted or fused overlapping area of ​​the material layers on the (solid) ground. Therefore, the pressure acting on the joint depends on the weight of the welding robot 1 and any additional weight 25. The advantage of the bottom-mounted welding robot design is that no counter roller is required, thus simplifying operation.

[0063] A contact heating device 10 is used to connect weldable and / or adhesively bonded, flat, flexible material layers to one another in a thermally inductive, material-locking manner. The material layers are configured as material webs, strips, and / or segments and are arranged at least partially overlapping. The contact heating device comprises a first connecting electrode 11 and a second connecting electrode 12, as well as a heating element 14 connected between the connecting electrodes. The heating element 14 is configured as a flat, planar steel sheet blank to which current is directly supplied. Exemplary embodiments of the contact heating device 10 are described in more detail with reference to the following figures.

[0064] According to one aspect of the present disclosure, the welding robot 1 can have one or more receiving arms for the contact heating device 10. Figures 1 to 3 In the example shown in FIG, the welding robot 1 has a first receiving arm 32 and a second receiving arm 33. The first receiving arm 32 is configured to receive the first connecting electrode 11 of the contact heating device 10. The second receiving arm 33 is configured to receive the second connecting electrode 12 of the contact heating device. Furthermore, the first and second receiving arms 32, 33 can be configured to provide a current supply to the heating element 14 of the contact heating device 10 via the first and second connecting electrodes 11, 12. In other words, the receiving arms 31, 32 can be used both for mechanical fastening and for supplying current to the contact heating device 10.

[0065] like Figures 1 to 3 As shown in FIG, the receiving arms 31 and 32 can be arranged and configured so that the contact heating device 10 is held in front of the pressure roller 21 of the chassis 20 of the welding robot 1 in the direction of movement 31. The contact heating device is thus positioned immediately in front of the location where the material layers previously heated by the contact heating device are subjected to pressure by the pressure roller 21 and connected to one another. The receiving arms 32 and 33 can be arranged one above the other in the same plane. An electrical insulator can be provided between the receiving arms 32 and 33. This arrangement ensures high stability while simultaneously preventing short circuits between the current-carrying receiving arms 32 and 33. A further advantage of designing the receiving arms 32 and 33 as fastening elements is that they provide a certain degree of mechanical flexibility. For example, this allows for compensating for unevenness in the floor or in the material layers to be connected.

[0066] The welding robot 1 can have a heating power control coupled to the drive speed, which increases the heating power as the speed increases, and vice versa. Due to the low thermal mass of the contact heating device 10, particularly rapid heating power control and temperature adaptation are possible. The welding robot 1 can be configured, for example, to provide a heating power between 250 W and 3600 W, particularly between 500 W and 2500 W, particularly between 1000 W and 2000 W, for example, 1500 W. The welding robot 1 can be configured for feed speeds between 5 m / min and 30 m / min, particularly between 10 m / min and 25 m / min, for example, up to 20 m / min. The width of the heating element (transverse to the feed direction during operation) can be between 10 mm and 100 mm, particularly between 15 mm and 75 mm, and particularly between 20 mm and 50 mm. Exemplary widths of the heating element are 20 mm, 30 mm, 40 mm, and 50 mm. An advantage of this embodiment can be that the heating element is mechanically flexible but nevertheless sufficiently stable.

[0067] An exemplary embodiment of the contact heating device 10 will be described below.

[0068] Figure 4 and Figure 5 The figures show a perspective view and a top view of a configuration of a contact heating device 10. The contact heating device 10 comprises a first connecting electrode 11 and a second connecting electrode 12 as well as a heating element 14 connected between the connecting electrodes 11, 121. The heating element 14 is designed as a flat, planar steel sheet blank to which current is directly supplied.

[0069] The sheet steel blank of the heating element is mechanically flexible and can be designed in particular to compensate for base unevenness. The sheet steel blank of the heating element has a thickness between 0.1 mm and 1.5 mm, in particular between 0.5 mm and 1.0 mm, in particular between 0.7 mm and 0.9 mm.

[0070] like Figure 4 and Figure 5 As shown in FIG, the sheet steel blank of the heating element 14 can have at least one partial cutout 17 in the longitudinal direction. In particular, the sheet steel blank of the heating element has a flat, U-shaped geometry. Here, the sheet steel blank of the heating element 14 can include the following components: a first, flat, planar leg 18 connected to the first connecting electrode 11; and a second, flat, planar leg 19 connected to the second connecting electrode 12. The first leg 18 and the second leg 19 lie flat, side by side, in the same plane. However, it is also conceivable for the first leg 18 and the second leg 19 to be arranged flat, one above the other. At the heating element tip, the sheet steel blank has a connecting region 41 that connects the first leg 18 and the second leg 19 to one another. In other words, the current supplied by the first and second connecting electrodes 11 and 12 is conducted via the first and second legs 18 and 19 to the connecting region 41 of the heating element 14. The portion of the sheet metal blank that is designed to provide at least 70%, in particular at least 80%, and in particular at least 90% of the heating power of the contact heating device can be considered a heating element. Conversely, depending on the design, the portion of the sheet metal blank that is connected to the connecting contacts 11 , 12 contributes less to the heating power.

[0071] As described at the outset, the contact heating device 10 with the heating element 14 can be designed to provide an increased temperature in the connecting region 41 compared to the supporting arms 18 , 19 . Figure 6 and Figure 7 The exemplary temperature distribution of different designs is shown in FIG. Figure 6It is obvious that an increased temperature occurs in the connection region 41 at the transition of the support arms. However, the temperature distribution can preferably be influenced by the connection region 41 having a structuring 16 which is designed to further influence the temperature distribution. In particular, the connection region 41 can have a structuring 16 in the form of a cutout or groove or opening which is designed to provide a temperature distribution in comparison to an unstructured cross section (see Figure 6 ) to locally reduce the current-carrying cross section and thus locally increase the heating power (see Figure 7 ). The cutout can be designed, for example, as a punched or laser-machined groove in the sheet metal blank.

[0072] Figure 7 Shown with Figure 4 and Figure 5 The structuring 16 changes the current distribution and thus also the heating power in such a way that, on the one hand, the current density in the connection region arranged at the rear edge relative to the movement direction 31 is increased and thus a higher temperature is achieved, and, on the other hand, the current density is more uniform over the width of the heating element 14 of the contact heating device.

[0073] like Figure 4 、 Figure 5 and Figure 7 As shown in , the cutout can be designed as an elongated groove, in particular as an elongated groove at an angle to the rear edge of the heating element tip, in particular at an angle between 20° and 80°, in particular between 30° and 60°.

[0074] It goes without saying that a structured portion in the form of a cutout (or groove or opening) can be provided for locally reducing the current cross section compared to an unstructured cross section and thus locally increasing the heating power, and the structured portion is not limited to elongated cutouts, but can also be provided in other shapes. Figure 8 , for example, shows a further embodiment of a contact heating device 10 , in which the grooves are provided in the form of circular openings, wherein the arrangement and density of the grooves are designed to produce a predetermined temperature distribution.

[0075] like Figure 4 、 Figure 5 、 Figure 7 and Figure 8 As shown in , the cutouts can be arranged symmetrically at least in sections. In particular, they can be arranged fan-shaped like a tree. This also allows for a better distribution of the current to the outer regions of the sheet metal blank. The advantage of this design is a more uniform temperature distribution across the width of the heating element 10.

[0076] exist Figure 4In the embodiment shown in , the first and / or second connecting electrode 11, 12 is formed by an extension of the steel sheet blank. The extension projects laterally beyond the heating element 14, in particular transversely to the feed direction 31. The first and second connecting electrodes 11, 12 are arranged laterally at the heating element and on the same side of the heating element. In particular, the extension of the steel sheet blank can be designed such that the first and / or second connecting electrode 11, 12 is arranged elevated relative to the plane in which the flat, planar steel sheet blank of the heating element 14 is located; in particular, the first connecting electrode 11 and the second connecting electrode 12 are arranged at different heights. This can provide an advantageous fastening, such as, for example, a fastening at the first and second receiving arms 32, 33 (such as Figures 1 to 3 The same applies to Figure 8 The embodiment shown in .

[0077] Regarding the connection electrodes 11 and 12, Figure 6 Another possible design is shown in FIG, in which the first and second connecting electrodes are also formed by an expansion of the sheet steel blank and are in each case partially overlapping or arranged one above the other. The region of the sheet steel blank in which the heating element is formed continues to be designed as a flat, planar sheet steel blank with direct current flow. Only the section of the connecting electrode that does not contribute significantly to the heating power is partially located outside the flat plane of the heating element.

[0078] Optionally, a step 15 can be provided at the tip of the contact heating device 10 or at the rear edge in the working movement direction 31 , such as for example Figure 5 and Figure 8 This enables the contact heating device 10 with the heating element 14 to be set very close to the pressure roller 21, as shown in FIG. Figures 1 to 3 As shown in . The grading portion 15 can be provided on the upper side or the lower side, or a double grading portion (Doppel phase) can be provided on the upper side and the lower side.

[0079] A folded edge 13 can be provided at the front edge of the contact heating device 10 in the working direction 31. This folded edge 13 can be formed, for example, by bending or folding sections of a sheet metal blank. This prevents the wedge from getting caught during layer jumps. Furthermore, mechanical stability can be improved, with flexibility being maintained, in particular, in the working direction.

[0080] In other words, according to one aspect of the present disclosure, the contact heating device 10 can be formed from a flat steel sheet blank, which is generally rectangular and consists of an electrically conductive, high-temperature-resistant and corrosion-resistant alloy, such as, for example, stainless steel 1.4301. The use of a flat steel sheet results in a high mechanical flexibility of the contact heating device 10, which has a positive effect on the thermal contact between the contact heating device 10 and the welding material, which is essential for a good welding quality. Due to the flexibility, unevenness or slight incorrect settings or incorrect operation can be compensated. In the longitudinal direction, the steel sheet blank can have partial cutouts 17, which produce, for example, Figure 4 The U-shaped geometry shown in Figure 1 is used. Electrical contacts 11 and 12 are located at both ends of the "U" to energize the steel sheet. These contacts also serve as mechanical fastening. Here, the electrical power is converted directly into thermal power in the steel sheet. Thus, the steel sheet blank acts as a heating conductor.

[0081] On the one hand, the U-shape has the advantage of increasing the ratio between the heating conductor length and the heating conductor width for the same area, and thus also increasing the resistance, which in turn simplifies the feeding. The higher the resistance, the lower the current required to achieve a specific heating power. This allows, in particular, to reduce the cross section of the supply line, thus saving costs. On the other hand, Figure 1 As shown in , the U-shape simplifies electrical and mechanical coupling to welding equipment without interfering with the welding process.

[0082] Current flow through the U-shaped heating conductor causes it to heat up. For welding applications, it is advantageous if the heating conductor is heated as evenly as possible across its width. However, in the turning area, also referred to as the connection area 14, the current density at the inner radius will be greater than at the outer radius, since the current path is shorter at the inner radius and the local resistance is therefore lower (the current takes the path with the lower resistance). Figure 6 As shown in , this results in a more intense heating of the heating conductor at the inner radius than at the outer radius. To counteract this, the contact heating device 10 according to one aspect of the present disclosure has a structuring 16 in the deflection region or in the connection region 14 of the arms 18, 19 at the inner radius, for example in the form of a cutout, as shown in Figure 4 and Figure 5 These structures narrow the line cross section at the inner radius and thus increase the local resistance, so that the current density in the deflection area is distributed more evenly over the deflection width and thus also achieves more uniform heating over the width in this area, as shown in Figure 7 Furthermore, the structuring 16 can also improve the heating distribution in the longitudinal direction by achieving maximum heating in the region of the rear heating wedge tip, as shown in FIG. Figure 7This is advantageous for good weld seam quality, since pressing also takes place directly in this area or directly afterwards, as shown in FIG. Figures 1 to 3 As shown in .

[0083] The structuring 16 in the form of a fork has the advantage that, even with a lower intensity, the current still flows through the structured area and thus heats it, which is advantageous for a uniform distribution, e.g. Figure 7 As shown in .

[0084] Figure 9 Another embodiment of a contact heating device 10 is shown, which is particularly suitable for (full-surface) welding of asphalt webs. For example, two lower material layers can be arranged side by side, with the abutment area or any gaps between the lower material layers being covered by the upper material web overlapping the lower material layers. This allows for an efficient seal to be created between the two lower material layers.

[0085] like Figure 9 As shown in , the contact heating device 1 can have multiple heating elements 14 connected between connecting electrodes 11, 12, each of which is designed as a flat, planar steel sheet blank to which current is directly supplied. In this case, structuring in the area of ​​the heating wedge tip is less important because, on the one hand, asphalt webs are more tolerant, particularly due to their generally greater material thickness; and, on the other hand, the arrangement of multiple heating elements 14, 14', ... 14" alongside one another also achieves a homogenizing effect, at least across the width of the weld seam or the entire contact heating device. However, the use of structuring can further improve the temperature distribution.

[0086] Figure 10 Shown with Figure 9 , a perspective view of a welding robot 50 of a contact heating device 10 is shown in FIG, wherein the pressure roller 21 is raised. Figure 11 Shown from Figure 10 A perspective view of a welding robot 50 is shown, with the pressure roller 21 lowered. The welding robot 50 can be configured as a mobile welding robot 50 for the full-surface joining of an asphalt web to an already laid asphalt web. The welding robot 50 can comprise a frame 51, on the upper side of which a handle 52 is arranged and on the lower side of which a receptacle 53 for the contact heating device 10 and the lowerable pressure roller 21 are provided.

[0087] The welding robot 50 can be configured, for example, to provide a heating power between 2 kW and 20 kW, particularly between 5 kW and 15 kW, for example, 10 kW. The welding robot 50 can be configured for a feed rate between 0.5 m / min and 30 m / min, particularly between 1 m / min and 10 m / min, particularly between 1 m / min and 5 m / min, for example, 1.5 m / min or 3 m / min. The width of the heating element (transverse to the feed direction during operation) can be between 10 mm and 1.5 m, particularly between 20 cm and 1.5 m, particularly between 0.5 m and 1.2 m, for example, a width of 1 m or 1.2 m. Multiple adjacently arranged heating elements 14, 14'...14', each designed as a directly energized flat sheet steel blank, allow for cost-effective production and flexible adaptation to uneven ground surfaces, such as can occur when sealing a roof. Furthermore, the use of such a welding robot makes it possible to dispense with open flames, as is customary when laying asphalt, thereby increasing safety.

[0088] Figure 12 A handheld device 60 with a contact heating device 10 is shown. Figure 13 Shown for Figure 12 A top view of a contact heating device 10 for a handheld appliance 60 is shown. The handheld appliance 60 has a housing body 61, which can also serve as a handle. In one embodiment of a battery-operated handheld appliance 60, the handheld appliance includes a battery 62. The battery 62 can be integrated into the housing body 61, or designed as a replacement battery, for example, coupled to or integrated into the housing body 61. The handheld appliance 60 can also have an operating element 63. The operating element 63 can be used to set the desired temperature or heating power, for example.

[0089] The contact heating device 10 can be fastened to the housing 61 via a first connecting electrode 11 and a second connecting electrode 12 and can also be supplied with current simultaneously. A heating element 14 is connected between the connecting electrodes 11, 12. The heating element 14 is designed as a flat, planar steel sheet blank that is directly energized. The heating element can have one or more other features, such as structuring, as described within the scope of this disclosure, in order to provide a desired temperature distribution.

[0090] The proposed handheld device 60 can be used, for example, for detailing or repairing material webs to be connected. For bitumen sealing, for example, bitumen web sections can be welded manually. The proposed handheld device can also be advantageous in locations that are difficult to access. Alternatively, Figure 12 and Figure 13The contact heating device 10 shown in FIG can have a deflection portion or be configured as a bent contact heating device 10. This facilitates lateral insertion and working along the connection area between the material layers to be connected. Furthermore, this handheld device avoids the use of open flames typically used during asphalt laying, thereby increasing safety.

[0091] The handheld device 60 can be configured to provide a heating power of, for example, between 100 W and 3600 W, in particular between 250 W and 2500 W, in particular between 1000 W and 2000 W, for example, 1500 W. The handheld device 1 can be configured for a feed speed of between 5 m / min and 30 m / min, in particular between 10 m / min and 25 m / min, for example, up to 20 m / min. The width of the heating element (transversely to the tip) can be between 10 mm and 100 mm, in particular between 15 mm and 75 mm, in particular between 20 mm and 50 mm. Exemplary widths of the heating element are 20 mm, 30 mm, 40 mm, and 50 mm. This design can be advantageous in that the heating element, despite being mechanically flexible, is still sufficiently stable.

[0092] Figure 14 A flow chart of a method 100 for thermally inductively bonding flat, flexible material layers using a contact heating device is shown. In particular, this method can be used in conjunction with a contact heating device 10 having a plurality of heating elements 14, 14', ... 14'', as shown in the example of Figure 9 As shown in .

[0093] In a first step S101 , the voltage drop U across the respective heating element 14 , 14 ′, . . . 14 ″ is measured. R1 、U R2 、…U RN In the subsequent step S102, based on the measured voltage drop U R1 、U R2 、…U RN The temperature-dependent partial resistance of the respective heating elements 14, 14', ... 14" is determined. In step S103, the temperature distribution across the width of the contact heating device 10 is determined based on the partial resistance of the respective heating elements 14, 14', ... 14". The proposed method enables monitoring of the welding temperature during the thermally inductively bonded connection of flat, flexible material layers. This design can offer advantages in improved quality assurance and documentation.

[0094] For example, if one of the heating elements should no longer be in contact with the material web, or only be in poor contact with it (e.g., due to a folded design of the material web), the corresponding heating element will heat up more intensely because the heat is no longer dissipated through the material of the material layer. The resistance of the heating element will increase, and therefore the partial voltage will also increase compared to the other heating elements. The proposed method can display and monitor this situation. This can thus improve process reliability when thermally joining material layers.

[0095] In summary, the solution proposed here can provide an improved contact heating device, an improved automatic joining device, and / or an improved handheld device for thermally inductively bonding weldable and / or adhesively bonded flat, flexible material layers to one another, the material layers being configured as material webs, material strips, and / or material segments and arranged at least partially overlapping. This improves handling and makes operation easier even for inexperienced users. Furthermore, the proposed solution contributes to further improvements in operational safety, efficiency, and / or welding speed.

Claims

1. A contact heating device (10) for connecting weldable and / or adhesively bonded flat flexible material layers to one another in a thermally inductively cohesive manner, the material layers being designed as material webs, material strips and / or material segments and being arranged at least partially overlapping, the contact heating device comprising: - a first connecting electrode (11) and a second connecting electrode (12); and - a heating element (14) coupled between the coupling electrodes (11, 12); in, The heating element (14) is designed as a flat, planar steel sheet blank to which current is directly supplied.

2. The contact heating device (10) according to any one of the preceding claims, wherein The sheet steel blank of the heating element (14) has at least one partial cutout (17) in the longitudinal direction, in particular the sheet steel blank of the heating element has a flat U-shaped geometry.

3. The contact heating device (10) according to any one of the preceding claims, wherein The steel sheet blank of the heating element (14) has the following components: a first flat, planar support arm (18) connected to the first connecting electrode (11); a second flat, planar arm (19) connected to the second connecting electrode (12); wherein the first arm (18) and the second arm (19) are flatly arranged above and below each other or side by side in the same plane; and The sheet steel blank of the heating element (14) has a connecting region (41) at the heating element tip, which connects the first leg (18) and the second leg (19) to one another.

4. The contact heating device (10) according to claim 3, wherein: The heating element (14) is designed to provide an increased temperature in the connecting region (41) compared to the support arms (18, 19).

5. The contact heating device (10) according to claim 3 or 4, wherein: The connecting region has a structuring (16) in the form of a cutout, which is designed to locally reduce the current-carrying cross section compared to an unstructured cross section and thus to locally increase the heating power.

6. The contact heating device (10) according to claim 5, wherein: The cutouts are arranged symmetrically at least in sections, in particular wherein the cutouts are arranged fanning out in a tree-like manner.

7. The contact heating device (10) according to any one of the preceding claims, wherein The first and / or second connecting electrode (11, 12) is formed by an expansion of the sheet steel blank and projects laterally, in particular transversely to a feed direction (31) for thermally connecting the material layers, beyond the heating element (14).

8. The contact heating device (10) according to any one of the preceding claims, wherein The sheet steel blank of the heating element (14) has a thickness between 0.1 mm and 1.5 mm, in particular between 0.5 mm and 1.0 mm, in particular between 0.7 mm and 0.9 mm.

9. The contact heating device (10) according to any one of the preceding claims, wherein The sheet steel blank of the heating element (14) is mechanically flexible and is designed, in particular, to compensate for base unevenness.

10. The contact heating device (10) according to any one of the preceding claims, wherein In addition to the sheet metal blank forming the heating element (14), a further section of the sheet metal blank is provided, wherein the further section of the sheet metal blank has a fold (13) at the rear end, which is formed by folding or folding the further section of the sheet metal blank.

11. The contact heating device (10) according to any one of the preceding claims, wherein The sheet steel blank comprises an electrically conductive, high-temperature-resistant and corrosion-resistant alloy, in particular stainless steel.

12. The contact heating device (10) according to any one of the preceding claims, wherein The contact heating device comprises a plurality of heating elements (14, 14', 14") connected between the connecting electrodes (11, 12), wherein each of the heating elements is designed as a flat, planar steel sheet blank to which current is directly supplied.

13. An automatic joining device (1) for the heat-inductive, material-locking joining of flat, flexible material layers, comprising a contact heating device (10) according to any one of the preceding claims.

14. A handheld appliance (60), in particular a battery-operated handheld appliance, for the thermally inductive, material-bonding connection of flat, flexible material layers, comprising a contact heating device (10) according to any one of the preceding claims.

15. A method (100) for thermally inductively bonding flat, flexible material layers using a contact heating device (10) according to claim 12, the method comprising the following steps: - measuring the voltage drop across the corresponding heating element (S101); - determining the temperature-dependent partial resistance of the respective heating element based on the measured voltage drop ( S102 ); and - determining the temperature distribution over the width of the contact heating device based on the partial resistances of the respective heating elements (S103).

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