Feeding a strip of material to a welding area, especially for thermoplastic welding.

Abstract

The invention relates to a device for feeding a strip of material (1), in particular made of thermoplastic material, to a welding area in which the strip of material (1) is welded to components to be joined. The strip of material (1) can be pressed against the components in the welding area by means of a pressure unit (4). The device comprises at least a first deflection roller (24) and a second deflection roller (25) for guiding the strip of material (1), the second deflection roller (25) being located at a smaller distance from the welding area than the first deflection roller (24). The first deflection roller (24) is configured to guide the strip of material (1) to the second deflection roller (25) by means of contact on a first surface of the strip of material (1) facing the components.The second deflection roller (25) is designed to guide the material strip (1) to the pressure unit (4) by means of contact on a second surface of the material strip (1) opposite the first surface.

Description

[0001] The invention relates to a device for feeding a strip of material to a welding area. The device is particularly suitable for feeding a strip of material made of a thermoplastic material to a welding area in which two components are joined together by thermoplastic welding. The components can be, for example, elements of aircraft fuselages or other components made of carbon fiber reinforced plastic (CFRP). However, the device can also be used in other welding processes and / or for joining other components.

[0002] In many areas, innovative materials such as CFRP, which combine high rigidity with low weight, are increasingly being used. However, these materials also require new manufacturing processes to join the CFRP components together.

[0003] One example of an area in which CFRP materials can offer significant advantages is aircraft construction, where the weight of all components plays a crucial role. Significant weight savings can be achieved, in particular, by manufacturing the aircraft's fuselage shell from CFRP. In modern commercial or cargo aircraft, the fuselage shell is usually made up of several sections arranged one behind the other in the longitudinal direction of the aircraft. These sections are essentially barrel-shaped and each consist of several fuselage shell elements, which in turn each form part of the fuselage section in the circumferential direction and are connected to one another for this purpose. In particular, the fuselage sections can each consist of an upper and a lower half shell, which are joined together at the sides of the fuselage sections along a connecting joint running in the longitudinal direction of the aircraft.

[0004] Thermoplastic welding is a suitable process for joining components made of thermoplastic CFRP. In this process, the components to be joined are brought into contact with one another, forming a weld seam in the contact area. For this purpose, a strip of material, also made of thermoplastic material, is continuously fed to the weld seam. The strip of material is brought towards the components in the welding area and, shortly before contact with the components, the strip and the components are heated using a laser so that the surfaces of the strip and the components at least partially enter a deformable phase. After heating, the strip of material is pressed against the components in the welding area, for example using one or more rollers, and is thereby consolidated so that the strip forms an integral connection with the components. The welded area then solidifies upon cooling.

[0005] The weld seam between two components is preferably formed using continuous material strips. Depending on the longitudinal dimension of the components to be joined, the material strips can be several meters long. The width of the material strips can vary along their longitudinal dimension, for example, to create a wider weld seam with increased strength in certain sections. Furthermore, the material strips made of thermoplastic material are comparatively stiff in their initial state. This means that the curvature of the material strips must not fall below a certain minimum bending radius to avoid damage to the material strips.

[0006] For the welding process, it is advantageous if the material strip is fed into the welding area in a controlled manner, so that it enters the welding area at the correct angle relative to the weld seam, where it can first be heated and then pressed. The angle between the impinging material strip and the surfaces of the components to be joined should be sufficiently large to allow the heating element, especially a laser unit serving as such, to be positioned between the material strip and the components without exceeding the minimum bending radius of the material strip or otherwise inducing significant stresses in the material.

[0007] Furthermore, the material strip should be fed into the welding area in the correct position, in particular, lateral displacement and / or sagging of the material strip should be avoided. It should also be noted that the material strip can, in principle, be guided in any spatial orientation, allowing gravity to act on the material strip from different directions. In the previously described case of a connection between two half-shells of an aircraft fuselage section, for example, the material strip can be guided so that its transverse extension is in the vertical direction.

[0008] Against this background, it is an object of the present invention to provide a device for the controlled feeding of a material strip to a welding area at the connecting joint between two components. In particular, the device should be capable of feeding the material strip to the welding area in the correct position and with a limited bending radius such that space remains between the material strip and the connecting joint or the components for the arrangement of a heating element.

[0009] According to one aspect, the invention proposes to solve the problem a device for feeding a material strip, in particular made of thermoplastic material, to a welding area in which the material strip is welded to components to be joined, wherein the material strip can be pressed against the components in the welding area by means of a pressing unit.The device has at least a first and a second deflection roller for guiding the material strip, and the first deflection roller has a smaller distance from the welding area than the second deflection roller, wherein the first deflection roller is designed to guide the material strip to the second deflection roller by contacting a first surface of the material strip facing the components, and wherein the second deflection roller is designed to guide the material strip to the pressing unit by contacting a second surface of the material strip opposite the first surface.

[0010] The arrangement of the first and second deflection rollers allows the material strip to be fed into the welding area at a specific, particularly relatively flat, angle, so that it can be pressed against the components to be joined by the clamping unit without exceeding the minimum bending radius of the material strip. Due to the guidance via two deflection rollers, the material strip can be guided tightly, ensuring controlled feeding of the material strip at the specified angle and with correct positioning.

[0011] In one embodiment, the material strip is fed to the welding area from a starting position in which the material strip is arranged along a connecting joint between the components. Due to the double deflection of the material strip by means of the first and second deflection rollers, a relatively large distance can remain between the not yet welded sections of the material strip and the components when fed from such a starting position, which in particular makes it possible to create a relatively large space for arranging a laser unit serving as a heating element between the material strip and the components. Such an arrangement of the laser unit is expedient so that the laser beam can be directed onto the surface of the material strip facing the components and onto the components in order to heat them.

[0012] Another embodiment provides for the material strip to be guided in such a way that it runs in an arc whose endpoints are essentially located at the first deflection roller and the pressure unit, while the second deflection roller contacts the material strip in the area of ​​the arc. In this embodiment, the material strip is fed to the welding area with a uniform bend that is present over a larger section of the material strip. This avoids the need to deflect the material strip at specific points with small bending radii, which could lead to tension in the material strip.

[0013] A connected embodiment is characterized in that the device comprises an arcuate sliding element that interacts with the second deflection roller, the second deflection roller being designed to press the material strip against the sliding element. Using such a sliding element, the previously explained feeding of the material strip in an arc can be reliably achieved. A further connected embodiment provides that the second deflection roller can be moved from an operating position into an insertion position, the second deflection roller being designed to press the material strip against the arcuate sliding element when it is in the operating position, and the deflection roller being at a greater distance from the sliding element in the insertion position than in the operating position.

[0014] Furthermore, in one embodiment, the device comprises a guide rail, via which the material strip can be guided to the first deflection roller, and which has a guide channel defined by opposing side elements with which the material strip can be fixed in the direction of its transverse extension. Fixing the material strip in this direction contributes to ensuring that the material strip can be fed to the welding area in the correct position relative to the connecting joint between the components, thus creating a stable connection between the components.

[0015] As previously explained, the width of the material strip can vary along its longitudinal extent. To nevertheless ensure reliable fixation of the material strip in the direction of its transverse extent, i.e., in its width direction, in one embodiment the side elements of the guide rail are movable, and a distance between the side elements is adjustable as a function of a first width signal representing a width or width change of the material strip. The first width signal can be determined by means of a first width query unit of the device, which is configured to detect the width or a width change of sections of the material strip before the sections of the material strip enter the guide rail.

[0016] The first width sensing unit can, in particular, be a component of a guide unit arranged on a side of the guide rail facing away from the first deflection roller and designed to fix the material strip in the direction of its transverse extent. Furthermore, the device can optionally comprise a second width sensing unit arranged in an end region of the guide rail facing the second deflection roller and designed to detect a second width signal representative of a width or width change of sections of the material strip located in the end region. If two width sensing units are present, each delivering a first and a second width signal, the distance between the side elements of the guide rail can be adjustable depending on the first and second width signals.Furthermore, embodiments provide that the first and / or the second width sensing unit has at least one sensing surface that is pressed against an edge of the material strip, and wherein the respective width sensing unit is designed to determine the width signal based on a detected position and / or position change of the sensing surface.

[0017] According to a further aspect, the invention proposes an arrangement for feeding a material strip, in particular made of thermoplastic material, to a welding area at a connecting joint between two components to be joined by thermoplastic welding using the material strip. The arrangement comprises a device of the aforementioned type and a mounting rail running along the connecting joint, wherein the material strip is fixed to the mounting rail, and wherein the device is movably mounted on the mounting rail and can be moved along the mounting rail for welding in order to feed the material strip to the welding area.

[0018] In one embodiment, the mounting rail further comprises a plurality of width-adjustable guide carriages which are movably mounted on the mounting rail and which are designed to hold the material strip, wherein the guide carriages are moved along the mounting rail by means of the device when the device is moved along the mounting rail.

[0019] The above-mentioned and further special features of the invention will also become clear from the following description of exemplary embodiments of the invention with reference to the figures. Fig. 1a a schematic and exemplary representation of components of an embodiment of a device for feeding a material strip to a welding area in a perspective view, Fig. 1b a schematic and exemplary representation of components of an embodiment of a device including the laser unit in a perspective view Fig. 2 a schematic and exemplary representation of parts of the device in a longitudinal section, Fig. 3 a schematic and exemplary view of components of the device, including a first and second deflection roller, and a pressing unit, Fig. 4 a schematic and exemplary view of a guide unit of the device with a width query unit, Fig. 5 a schematic and exemplary view of a guide rail of the device, and Fig. 6 a schematic and exemplary view of components of a width sensing unit of the device.

[0020] In the Fig. 1a, Fig. 1b and Fig. Figure 2 schematically shows, in a perspective view and in a longitudinal section, an exemplary embodiment of a device 20 for feeding a material strip 1 of variable width to a welding area. The feeding device 20 is a component of a welding device that can be used to join two components, which may be made of CFRP, by thermoplastic welding. Of the components, Fig. 2 of a section is illustrated and provided with the reference number 3.

[0021] The components 3 can, for example, be elements of an aircraft fuselage. The aircraft fuselage can be composed of several sections arranged one behind the other in the longitudinal direction, each of which is essentially barrel-shaped, and each of the sections can in turn consist of several of the aforementioned elements. The elements can form a portion of the overall circumference of a section. In particular, the elements can be upper and lower half-shells of the sections, which are joined together laterally at the section by welding. However, the invention is not limited to this intended use. Rather, the device according to the invention can also be incorporated into welding devices used for the thermoplastic welding of other components.

[0022] The connection between the components 3 will be created by applying one or more superimposed material strips 1 made of thermoplastic material, in particular also made of CFRP, to the components 3 in the area of ​​their connecting joint and connecting them to them. In the area of ​​the connecting joint, the components 3 can have a milled step or shoulder in the edge area into which the material strip(s) 1 are fitted, so that a large-area connection is created. If several superimposed material strips 1 are used, these can have different widths, larger in higher layers, which are fitted into corresponding gradations of adapted width. If several material strips 1 are used, the individual strips are applied one after the other in several welding processes, which are basically carried out in the same way.

[0023] The welding process performed using the welding device is explained below, particularly with regard to the welding of a material strip 1 that is applied directly to the components 3. This material strip 1 can be the first or bottommost material strip 1 of a plurality of material strips 1 that are applied in multiple layers. In this case, the welding process for welding the bottommost material strip 1 is followed by the further welding processes for welding the additional material strips 1, which can be performed in the same way using the welding device.

[0024] In order to join the components 3 together using the welding device, they are first positioned correctly relative to one another, i.e. they are brought into the relative position which the joined components 3 are to have. For this purpose, the components 3 can, for example, be fastened to a holding frame in the correct relative alignment. A material strip 1 is then arranged in an initial position in the region of the connecting joint between the components 3. In this position, the material strip 1 extends in its longitudinal extent along the connecting joint and is positioned at a certain distance above this connecting joint. In particular, the material strip 1 is arranged in its initial position such that the surface to be joined to the components 3 already points parallel to the surfaces of the components 3 at their connecting joint and that it runs in a direction perpendicular to this surface, offset from the connecting joint.During the welding process, the material strip 1 is then pressed in a direction perpendicular to the strip plane towards the connecting joint and against the components 3. For this purpose, the welding device is moved along the material strip 1 into a position shown in the . Fig. 2 is moved in the direction illustrated by the arrow 8, while the material strip 1 is essentially not moved in the longitudinal direction during the welding process.

[0025] The material strip 1 consists of a relatively rigid material. In order to avoid excessive tension within the material strip 1 or even damage to the material strip 1, the material strip 1 should not fall below a certain minimum bending radius. This must be taken into account, in particular, when feeding the material strip 1 to the welding area. Furthermore, the width of the material strip 1 can vary along its longitudinal extent. This makes it possible to accommodate different requirements for the connection between the components 3, which may exist in different sections of the components 3. For example, it can be provided that the material strip 1 has a greater width in one area at the edges of the components 3 than in the remaining areas.If the components 3 are the previously explained elements of an aircraft fuselage, the edges of the components 3 can, for example, define the cutouts for the cabin doors, and in the area of ​​these edges, the material strip 1 can have a greater width. This allows the components 3 to be reliably connected to one another in this area as well.

[0026] The welding device comprises, in the embodiment illustrated in the figures, a pressing unit 4 for pressing the material strip 1 onto the components 3 to be joined, a cooling element 5 for cooling the material strip 1 fused to the components 3, and a heating element designed as a laser unit 6, with which the material strip 1 is heated in the welding area. These and the other components of the welding device are suitably mounted on a support frame 7. In the figures, the laser unit 6 is only shown in the Fig. 1b and has been omitted from the remaining figures to improve clarity.

[0027] The cooling element 5 is preferably arranged in the area of ​​the pressing unit 4 and can be designed, for example, as a nitrogen cooling system. In this embodiment, liquid nitrogen is supplied to the cooling element 5 via a line system (not shown in the figures). The cooling element consists of nitrogen nozzles that release the nitrogen into the welding area for cooling. The cooling takes place during the welding process and ensures that the welding area does not overheat and that its surroundings do not become excessively hot.

[0028] The laser unit 6, which serves as a heating element, is arranged in a front area of ​​the welding device in the direction of movement 8 and is attached there to the support frame 7 of the welding device. It is designed in a manner known per se to generate laser light and to irradiate it within a laser beam 9 directed onto the welding area (in the Fig. 3 schematically shown). The laser light preferably has a wavelength that is highly absorbed by the material of the material strip 1. Furthermore, the laser unit 6 is designed such that the laser beam 9 has a sufficiently high intensity in the welding area to heat the surfaces of the material strip 1 and the components 3 in a short time, so that they at least partially transition into a plastic phase.

[0029] The cross-section of the laser beam 9 has a small extent in the welding area, which is smaller than the minimum width of the material strip 1. This ensures that the laser beam 9 only hits the components 3 and the material strip 1 in the welding area and not the area surrounding the welding area. In order to heat the material strip 1 across its entire width and also to heat the edge regions of the components 3 across the width of the material strip, the laser beam 9 is moved back and forth in an oscillating manner in a direction parallel to the transverse extent of the material strip 1. This can be achieved, for example, by an oscillating pivoting of the laser unit 6 and / or by an oscillating movement of one or more elements of a beam-guiding optics of the laser unit 6. The amplitude of the oscillating movement of the laser beam 9 is adjusted so that the laser beam 9 reaches both edges of the material strip 1.For this purpose, it is expedient that the respective width of the material strip 1 is detected in a manner to be described below and the amplitude of the oscillating movement of the laser beam 9 is adapted to the detected width.

[0030] The pressing unit 4 is arranged in a rear area of ​​the welding device in the direction of movement 8 and is intended to press the heated material strip 1 against the components 3 to be joined in the welding area such that it covers the connecting joint between the components 3 and the components 3 are connected to one another. In the embodiment illustrated in the figures, the pressing unit 4 comprises a rotatably mounted roller 10 for pressing the material strip 1. The axis of the roller 10 is aligned perpendicular to the direction of movement 8 of the welding device and, during operation of the welding device, parallel to the surfaces of the components 3 in the area of ​​their connecting joints.The roller 10 can be moved relative to the support frame 7 of the welding device in a direction perpendicular to the direction of movement 8 of the welding device and to the roller axis (here also referred to as the pressing direction), so that the roller 10 can be moved away from and towards the components 3 and pressed against the components 3 during operation of the welding device.

[0031] For this purpose, the pressing unit 4 can comprise one or more pressure cylinders 11, which are mounted on the one hand on the support frame 7 of the welding device and on the other hand are connected to the roller 10 or its axis. By means of the pressure cylinders 11, the roller 10 can be pressed against the components 3 during the welding process with an adjustable force, which can be, for example, between 0.2 kN and 12 kN, while the material strip 1 is located between the roller 10 and the components 3. In one embodiment, the pressure cylinders 11 are controlled by means of a control unit (not shown in the figures) such that the roller 10 is pressed against the components 3 with an adjustable pressure. For this purpose, a force sensor (also not shown in the figures) can be arranged on the roller 10 or the pressure cylinder 11, and the control unit can control the pressure cylinders 11 such that the force measured by the force sensor has a predetermined target value.

[0032] As previously mentioned, the welding device is moved along the joint between the components 3 to be joined during the welding process. As shown in the Fig. 1 and Fig. 2, the welding device is, in one embodiment, movably mounted via its support frame 7 on a mounting rail 12, which is arranged substantially parallel to the connecting joint between the components 3 to be joined in order to carry out the welding process. By means of a drive unit (not shown in the figures), the welding device is then moved along the mounting rail 12 during the welding process in order to produce the weld seam. Furthermore, a plurality of guide carriages 13a, b, c are movably mounted on the mounting rail 12, which are designed to hold the material strip 1 in its previously described starting position. For this purpose, the guide carriages 13a, b, c have receptacles for the material strip, the width of which is adjustable and can thus hold a material strip 1 of variable width.In the figures, three guide carriages 13a,b,c are shown as examples, but in principle any number of guide carriages 13a,b,c can be used.

[0033] To carry out the welding process, the material strip 1 is initially held in its starting position using the guide carriages 13a, b, c. For this purpose, it can be advantageous to position the guide carriages 13a, b, c at regular, suitably selected intervals along the length of the material strip 1 on the mounting rail 12. During the welding process, the device is then moved in the direction of movement 8 along the mounting rail 12 in order to create the weld seam. The welding device pushes the guide carriages 13a, b, c to the end of the mounting rail 12. The guide carriages 13a, b, c each remain in their starting position until the welding device or an adjacent guide carriage 13a, b, c abuts the respective guide carriage 3a, b, c and pushes it along the mounting rail 12 in the direction of movement 8.In this way, the guide carriages 13a,b,c are pushed together during the welding process and moved to the end of the mounting rail 12.

[0034] During the welding process performed by the welding device, the material strip 1 is fed from its previously described starting position to the components 3 by means of the feed device 20 into the welding area, where it is first heated and then pressed against the components 3 to be joined by the pressing unit 4. The feeding takes place while the welding device is moved along the connecting joint between the components 3.

[0035] During operation of the welding device, the laser unit 6 is located between the as yet unwelded part of the material strip 1 and the components 3, and the laser beam 9 strikes the surface of the material strip 1 facing the components 3 and the surface of the components 3 in the welding area. As a result, the surface of the material strip 1 facing the components 3 and the surface of the components 3 are heated, so that when the material strip 1 is subsequently pressed onto the components 3 by means of the roller 10 of the pressing unit 4, a reliable connection is created between the material strip 1 and the components 3. With this arrangement, however, the material strip 1 is at a relatively large distance from the components in the area of ​​the laser unit 6. To ensure that the minimum bending radius of the material strip 1 is not undercut, it is simultaneously necessary for the material strip 1 to be bent in the welding area orat the roller 10 at a relatively small angle to the surfaces of the components 3. For example, this angle is a maximum of 45 degrees, preferably a maximum of 30 degrees. Furthermore, the material strip 1 must be fixed in the transverse direction during feeding to the welding area so that it can be placed as precisely as possible on the connecting joint between the components 3 to be joined.

[0036] In order to feed the material strip 1 to the welding area in this manner and at such a small angle in a controlled manner, while simultaneously arranging the laser unit 6 at the aforementioned position, the feed arrangement in one embodiment comprises, in particular, a plurality of deflection devices 21, 22, 23 as well as a guide rail 23 and a guide unit 22, which are explained below. The components of the feed arrangement are preferably attached to the support frame 7 of the welding device so that they move together with the welding device during the welding process.

[0037] As in the Fig. 1 and Fig. As illustrated in Figure 2, the material strip 1 enters the feed device 20 via an input deflection 21 during the movement of the welding device and is deflected from its initial position at a first angle in the direction of the components 3. The input deflection 21 can be designed, for example, as a rotatable roller, and the angle is to be dimensioned in particular such that the minimum bending radius of the material strip 1 is not exceeded. The material strip 1 then passes via the guide unit 22 and the guide rail 23 to a first deflection roller 24, and from the first deflection roller 24 it is guided via a second deflection roller 25 to the roller 10 of the pressing unit 4.

[0038] In one embodiment, the deflection rollers 24 and 25 are arranged such that, when the welding device is in operation, the second deflection roller 25 is at a smaller distance from the components 3 than the first deflection roller 24 in the direction of movement 8 of the welding device and in the pressing direction. The deflection rollers are also positioned such that the material strip 1 is guided with its surface facing the components over the first deflection roller 24 and with its surface facing away from the components over the second deflection roller 25. As a result, the material strip 1 is deflected further in the direction of the components by the first deflection roller 24 and in the opposite direction by the second deflection roller 25 before it reaches the roller 10 of the pressing unit 4.The deflection rollers 24 and 25 as well as the roller 10 are arranged such that the material strip 1 is guided in an arc with a curvature that is as uniform as possible from the first deflection roller 24 via the second deflection roller 25 to the roller of the pressing unit 10, wherein the radius of the arc is selected to be sufficiently large, in particular larger than the minimum bending radius of the material strip 1.

[0039] The first deflection roller 24 and the second deflection roller 25 can be substantially cylindrical bodies that are mounted for rotation about their axis of symmetry. The deflection rollers 24, 25 have a surface suitable for guiding the material strip 1 without damaging it. Both deflection rollers 24, 25 can have different diameters and widths. In particular, the second deflection roller 25 can have a width that is smaller than the width of the material strip 1, while the first deflection roller 24 is preferably somewhat wider than the material strip 1 in order to support the material strip 1 across its entire width. Furthermore, in one embodiment, the first deflection roller 24 has a smaller diameter than the second deflection roller 25.

[0040] To ensure the curved guidance of the material strip 1 and to fix it in place, the feed device can comprise a curved sliding element 26. This has a curved sliding surface that allows the material strip 1 to slide along the sliding element 26 with low friction. The sliding element 26 is arranged opposite the second deflection roller 25 and cooperates with it to guide the material strip 1. For this purpose, the second deflection roller 25 can be moved between an operating position and an insertion position. This can be achieved, for example, by mounting the second deflection roller 25 on a linear drive. This can be connected to a controller that can move the second deflection roller 25 between the insertion position and the operating position as needed.

[0041] In the operating position in which they are in the Fig. 2 and Fig. As shown in Figure 3, the second deflection roller 25 presses the material strip 1 against the sliding element. As a result, the material strip 1 rests against the sliding element 26 and consequently extends in an arc whose curvature is determined by the sliding element 26. With a suitable selection of this curvature, the material strip 1 can thereby be held in the previously described position, in which it extends from the first deflection roller 24 to the roller 10 of the pressing unit 4 in a substantially uniform curvature.

[0042] To move the second deflection roller 25 from the operating position to the insertion position, it is moved in a radial direction relative to the arc described by the material strip 1, toward the center of the arc (i.e., away from the material strip 1). When the deflection roller 25 is in the insertion position, the material strip 1 can be inserted into the feed device, for example, by hand, and in particular correctly positioned between the second deflection roller 25 and the sliding element 26. By moving the second deflection roller 25 from the insertion position to the operating position, the material strip 1 can then be fixed between the second deflection roller 25 and the sliding element 26.

[0043] The guide unit 22 and the guide rail 23, which are arranged between the input deflection 21 and the first deflection roller, serve primarily to fix the position of the material strip in the direction of its transverse extension.

[0044] The Fig. The guide unit 22, shown in more detail in Figure 4, receives the material strip 1 after it has passed the input deflection 21. To guide the material strip 1, the guide unit 22 comprises opposing lateral guide elements 27a,b, which form lateral boundaries for the material strip 1 and thereby fix its position in the direction of its transverse extent. In order to be able to guide material strips 1 of different widths, the distance between the guide elements 27a,b can be changed. For this purpose, the guide elements 27a,b are each connected to a drive unit 28a,b, which is designed to displace the connected guide element 27a,b in the direction of the transverse extent of the material strip 1. The drive units 28a,b are designed, for example, as electric linear drives, but other designs are also possible.The displacement of the guide elements 27a,b preferably takes place essentially synchronously in opposite directions, so that the position of the central axis of the intermediate space between the guide elements 27a,b remains unchanged.

[0045] The distance between the guide elements 27a,b is adjusted depending on a width signal provided by a first width sensing unit 29 for determining the width of the material strip 1. This is preferably a component of the guide unit 22. In an embodiment described in the Fig. 6 is illustrated in more detail, the first width sensing unit 29 detects the width of the material strip 1 mechanically by means of opposite sensing surfaces 30, of which Fig. 6 only one is shown.

[0046] The sensing surfaces 30 are integrated into the lateral guide elements 27a,b of the guide unit 22. During operation, they are pressed against the edges of the material strip 1 and thus remain in contact with the material strip 1. The pressing of the sensing surfaces 30 against the material strip 1 can each be achieved using one or more spring elements 40, whereby the pressure exerted on the material strip 1 is preferably dimensioned such that the material strip 1 does not deform or become subjected to significant stresses. To generate the width signal, the position and / or position change of one of the sensing surfaces 30 is detected. In one embodiment, this is done using a position flag 31, which is firmly connected to the respective sensing surface 30 and whose position is continuously detected or whose position changes are detected.For this purpose, for example, a laser distance sensor 32 can be used, wherein the laser distance sensor 32 uses a laser beam for distance measurement in a manner known per se, which is reflected by the position flag 31.

[0047] The width signal for controlling the distance between the guide elements 27a,b is determined from the position measurements for the sensing surfaces 30 and, in one embodiment, represents the width of the material strip 1. In this embodiment, the distance between the guide elements is set such that it corresponds to the width of the material strip specified in the width signal. Alternatively, however, it can also be provided that the width signal represents changes in the width of the material strip 1, which are determined from position changes of the guide elements 27a,b. In this embodiment, the distance between the guide elements 27a,b is initially set according to the width of the material strip 1, for example when inserting the material strip 1 into the welding device, independently of the width signal.The distance between the guide elements 27a,b is then changed according to the width signal in order to guide the material strip 1.

[0048] From the guide unit 22, the material strip 1 passes to the guide rail 23, which is in the Fig. 5 and which also serves to fix the material strip 1 in the direction of its transverse extent. For this purpose, the guide rail 23 has two opposing side elements 33a,b which delimit a guide channel 34 which, during operation, extends in the direction of the longitudinal extent of the material strip 1 and through which the material strip 1 is guided during operation of the welding device. By means of the side elements 33a,b, the material strip 1 is fixed in the aforementioned direction within the guide channel 34. To guide material strips 1 of different widths, the distance between the side elements 33a,b can be changed. For this purpose, the side elements 33a,b are each connected to a drive unit 35a,b which is designed to move the connected side elements 33a,b in the direction of the transverse extent of the material strip 1.The drive units 35a,b, like the drive units 28a,b of the guide unit 22, can be designed as electric linear drives, although other configurations are also possible. The displacement of the side elements 33a,b by means of the drive units 35a,b preferably occurs essentially synchronously in opposite directions, so that the position of the center axis of the gap between the guide elements remains unchanged.

[0049] The guide channel 34 formed in the guide rail 23 is longer than the guide elements 27a,b of the guide unit 22, so that the guide rail 22 fixes the material strip 1 over a larger portion of its longitudinal extent than the guide unit 22. Thus, the guide rail 23 enables more reliable guidance of the material strip when the side elements 33a,b fix the material strip 1 over its entire longitudinal extent. This is the case when the width of the material strip does not change within the guide channel 34 of the guide rail 23. However, if the width of the material strip 1 changes within the guide channel 34, the guide channel 34 does not contribute to the lateral guidance of the material strip 1 over its entire length.However, in this case too, the material strip 1 is additionally guided in the direction of its transverse extension by the guide unit 22 arranged upstream of the guide rail 23, so that reliable lateral guidance is always guaranteed.

[0050] In one embodiment, the distance between the side elements 33a,b of the guide rail 23 is adjusted depending on the width signal of the first width sensing unit 29 integrated into the guide unit 22. In particular, a controller (not shown in the figures) uses this signal, taking into account the speed at which the welding device moves along the material strip 1, to determine the maximum width of the section of the material strip 1 located in the guide channel 34 and adjusts the distance between the side elements 33a,b according to this maximum width.

[0051] It can also generally be assumed that the width of the material strip 1 in sections whose length corresponds to that of the guide rail 23 or the guide channel 34 changes monotonically in the event of a change, i.e. the material strip 1 becomes either wider or narrower. If the width signal represents changes in the width of the material strip 1, the distance between the side elements 33a,b of the guide rail 23 is therefore controlled in one embodiment as a function of the width signal and the aforementioned speed such that if the width of the material strip 1 increases in a section of the material strip 1, the distance between the side elements 33a,b is increased when the section in question enters the guide channel 34 or when the spread is detected in the guide unit 22 (which is arranged immediately in front of the entrance to the guide rail 22).However, if the width of the material strip 1 decreases in a section of the material strip 1, the distance between the side elements 33a,b is reduced accordingly in accordance with the width signal when the distance in question has just left the guide channel 34 of the guide rail 23.

[0052] In a further embodiment, a second width sensing unit 36, which provides a second width signal, is provided in an end region of the guide channel 34 facing the welding area. The second width sensing unit 36 ​​can be designed in the same way as the previously described first width sensing unit 29. In particular, it can comprise touch surfaces 37, which are integrated into the side elements 33a,b and of which Fig.5, a tactile surface 37 is shown. During operation, the tactile surfaces are pressed against the edges of the material strip 1, for example, using spring elements. To generate the second width signal, the position of a tactile surface 37 is continuously detected, or changes in the position of the tactile surfaces 37 are detected. For this purpose, a position flag 38 can again be firmly connected to the respective tactile surface 37, the position or changes in position of which are detected in the manner described above by means of a laser distance sensor 39.

[0053] Using the first width signal detected by the second width sensing unit 36, the distance between the side elements 33a,b of the guide rail can be adjusted without recourse to the speed at which the welding device is moved along the material strip 1. If both the first and second width signals represent the width of the material strip 1 detected by the width sensing units 29, 36, the distance between the side elements 33a,b can be adjusted in particular so that it corresponds to the maximum value of the two detected width values.If the first and second width signals represent changes in the width of the material strip, the distance between the side elements 33a,b of the guide rail 23 can be controlled under the assumption already explained above such that, in the event of an increase in the width of the material strip 1 in a section of the material strip 1 indicated in the first width signal, the distance between the side elements 33a,b is increased when the section in question enters the guide channel 34 or when the spread in the guide unit 22 is detected by the first width query unit 29. Furthermore, the distance between the side elements 33a,b can be reduced in accordance with the second width signal if a reduction in the width of the material strip 1 can be inferred from this width signal.

[0054] Furthermore, the width signal provided by the second width sensing unit 36 ​​can also be used to control the amplitude of the previously explained oscillating movements of the laser unit 6 serving as heating elements or of the laser beam 9 emitted by the laser unit. In particular, the amplitude of the movement can be adapted to the width of the material strip 1 according to the width signal. This can be done in such a way that the laser beam moves across exactly the entire width of the material strip 1. This ensures that the material strip 1 is heated across its entire width, while at the same time preventing the laser beam from extending beyond the material strip 1. List of reference symbols 1 strip of material 3 Component 4 Pressing unit 5 Cooling element 6 Laser unit 7 supporting frames 8 Direction of movement 9 Laser beam 10 rollers 11 printing cylinders 12 mounting rail 13a,b,c guide carriage 20 Feeding device 21 Input redirection 22 management unit 23 Guide rail 24 first pulley 25 second pulley 26 Sliding element 27a,b guide element 28a,b drive unit 29 first width query unit 30 touch surface 31 Position flag 32 laser distance sensor 33a,b page elements 34 guide channel 35a,b drive unit 36 second width query unit 37 Touch surface of the second width sensor unit 38 Position flag of the second width sensor unit 39 Laser distance sensor of the second width sensing unit 40 spring element

Claims

[1] Device (20) for feeding a material strip (1), in particular made of thermoplastic material, to a welding area in which the material strip (1) is welded to components (3) to be joined, wherein the material strip (1) can be pressed against the components (3) in the welding area by means of a pressing unit (4), wherein the device (20) has at least a first deflection roller (24) and a second deflection roller (25) for guiding the material strip (1), and the second deflection roller (25) has a smaller distance from the welding area than the first deflection roller (24), wherein the first deflection roller (24) is designed to guide the material strip (1) to the second deflection roller (25) by contacting a first surface of the material strip (1) facing the components (3), and wherein the second deflection roller (25) is designed to guide the material strip (1) to the pressing unit (4) by contacting a second surface of the material strip (1) opposite the first surface. [2] Device (20) according to claim 1, wherein the material strip (1) can be fed to the welding area from a starting position in which the material strip (1) is arranged along a connecting joint between the components (3). [3] Device (20) according to claim 1 or 2, wherein the material strip (1) can be guided in such a way that it runs in an arc, the end points of which lie substantially at the first deflection roller (24) and at the pressing unit (4), while the second deflection roller (25) contacts the material strip (1) in the region of the arc. [4] Device (20) according to one of the preceding claims, further comprising an arcuate sliding element (26) cooperating with the second deflection roller (25), wherein the second deflection roller (25) is designed to press the material strip (1) against the sliding element (26). [5] Device (20) according to claim 4, wherein the second deflection roller (25) can be moved from an operating position to an insertion position, wherein the second deflection roller (25) is designed to press the material strip (1) against the arcuate sliding element (26) when it is in the operating position, and wherein the second deflection roller (25) has a greater distance from the sliding element (26) in the insertion position than in the operating position. [6] Device (20) according to one of the preceding claims, further comprising a guide rail (23) via which the material strip (1) can be guided to the first deflection roller (24) and which has a guide channel (34) which is delimited by opposite side elements (33a,b) with which the material strip (1) can be fixed in the direction of its transverse extent. [7] Device (20) according to claim 6, wherein the side elements (33a,b) are movable and a distance between the side elements (33a,b) is adjustable as a function of a first width signal representing a width or width change of the material strip (1), wherein the first width signal is ascertainable by means of a first width query unit (29) of the device (20) which is designed to detect a width or a width change of sections of the material strip (1) before the sections of the material strip (1) enter the guide rail (23). [8] Device (20) according to claim 7, wherein the first width sensing unit (29) is a component of a guide unit (22) which is arranged on a side of the guide rail (23) facing away from the first deflection roller (24) and is designed to fix the material strip (1) in the direction of its transverse extent. [9] Device (20) according to one of claims 7 or 8, further comprising a second width sensing unit (36) which is arranged in an end region of the guide rail (23) facing the second deflection roller (25) and is designed to detect a second width signal which is representative of a width or width change of sections of the material strip (1) which are located in the end region, wherein the distance between the side elements (33a,b) of the guide rail (23) is adjustable as a function of the first and the second width signal. [10] Device (20) according to one of claims 7-9, wherein the first width sensing unit (29) and / or the second width sensing unit (36) has at least one sensing surface (30; 37) which is pressed against an edge of the material strip (1), and wherein the respective width sensing unit (29; 36) is designed to determine the width signal on the basis of a detected position and / or position change of the sensing surface (30; 37). [11] Arrangement for feeding a material strip (1), in particular made of thermoplastic material, to a welding area at a connecting joint between two components (3) to be joined by means of the material strip (1) by thermoplastic welding, comprising a device (20) according to one of the preceding claims and a mounting rail (12) running along the connecting joint, wherein the material strip (1) is fixed to the mounting rail (12) and wherein the device (20) is movably attached to the mounting rail (12) and is movable along the mounting rail (12) for welding in order to feed the material strip (1) to the welding area. [12] Arrangement according to claim 11, further comprising a plurality of width-adjustable guide carriages (13a,b,c) which are movably mounted on the mounting rail (12) and which are designed to hold the material strip (1), wherein the guide carriages (13a,b,c), when the device (20) is moved along the mounting rail (12), are hereby moved by means of the device (20) along the mounting rail (12).

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