Method and device for welding at least two profiles for window or door frames or sashes

Description

[0001] The invention relates to a method for welding at least two profiles for window or door frames or sashes according to the preamble of claim 1 and to a device for welding at least two profiles according to the preamble of claim 11.

[0002] Methods and devices of the type mentioned above are known, for example, from DE 10 2015 107 121 A1 and are used in particular for welding PVC profile bars to form workpieces in the form of window or door frames or sashes. For this purpose, the profile bars are cut to the required lengths before welding, in order to subsequently join the profile parts or profiles together by welding at the cut surfaces forming the joining surfaces. If necessary, the profile parts can be mitered so that the mitered cut surfaces form the joining surfaces.

[0003] The actual welding of the profile parts within the meaning of the present invention is carried out by melting and subsequent joining of the joining surfaces at the profile bar ends. For this purpose, the profile parts to be welded are first placed in a corresponding clamping device and positioned relative to one another with the aid of stops and guides in the device. The joining surfaces are then pressed against the heating surface of a heating element of the welding device in a melting step. During the heating and equalization step that takes place, material from the respective profile part is melted at its joining surface, creating the melt required for the weld – i.e. material that has become liquid or pasty due to the effect of heat. By pressing the joining surface against the heating element, the so-called equalization, any unevenness on the joining surfaces is also melted away.

[0004] During the subsequent changeover, the heating element between the profile parts is removed before they are joined. Joining occurs by bringing both profile parts into contact and compressing them, with the molten joining surfaces being moved toward each other in the joining direction and pressed against each other. The still-hot, preferably thermoplastic material of the two profile parts, the melt, comes into contact and, after cooling, forms a stable weld. Such a process is described, for example, in DE 10 2012 112 533 A1.

[0005] The joining partners themselves are longer by an excess dimension than the final finished dimension of the joined elements of the workpiece. To form the melt, a portion of this excess, known as the burn-off, is melted away on the heating element. Another portion of the excess softens during the initial melting step and is compressed to the intended final dimension in the subsequent joining step. The ratio of the excess to the melting and compression is variable. The burn-off can be selected to be larger or smaller depending on the profile type used, ensuring sufficient melt is always available for a reliable weld.

[0006] During the melting step on the heating element, the material of the profile part, for example, PVC, begins to flow and deform at the joining surface. The melt, which is displaced by the pressing of the profile part against the heating element, also moves laterally outward over the edge of the joining surface to the outer surfaces, particularly the visible surfaces of the profile part.

[0007] The visible surfaces of the profile part are those external surfaces that are visible when the workpiece is finished and installed. For windows or doors, these are the surfaces of the individual profile parts that are visible in the window or door plane. Fastening elements, such as fittings, or other workpiece elements, such as window panes, can be arranged and attached to the functional surfaces of the profile parts, which usually extend transversely or perpendicularly to the visible surfaces.

[0008] In conventional joining processes, the excess melt from the profile parts cools during joining and forms a weld bead at the joint between the profile parts. However, such a weld bead on the outer surfaces of the profile part, especially on the visible surfaces, compromises the dimensional accuracy of the workpiece and impairs the impression of high quality. Therefore, after a certain cooling period, the weld bead is removed in downstream machines, such as finishing machines, for example, by milling shadow grooves or by flush cutting along the weld.

[0009] Foil- or laminated profiles are now also being used to manufacture window and door frames and sashes, allowing them to be easily decorated with different colors or designs. With such profiles, the necessary post-processing of weld beads in the joining area is difficult, as the thin foil or laminate layers can easily be damaged by mechanical processing. This can lead to increased, costly scrap, particularly in automated or semi-automated processes.

[0010] By removing the weld bead, the underlying base material of the profile part, which differs in color from the film or lamination, becomes visible and must be laminated by hand in a corresponding color.

[0011] For several years now, the ideal manufacturing concept has been to achieve a welding of profiles, especially those with a decoration, which results in visually appealing visible surfaces, whereby no weld seam should be created that protrudes beyond the visible surface and has to be deburred and / or re-colored.

[0012] Recent state-of-the-art solutions aim to prevent the formation of an external weld bead from the outset by specifically influencing the flow of the melt before and / or during joining. For example, the respective profile can be restricted using limiting elements, such as limiting blades, in order to reduce or prevent the melt from escaping via the visible surfaces. This is proposed, for example, in the documents DE 20 2015 000 908 U1, DE 10 2015 107 121 A1, DE 10 2016 102 240 A1 and DE 10 2016 104 785 A1. Some of these devices have shaped parts that can be moved before and / or during the initial melting step to influence the melt. The aim is either to prevent melt from escaping to the outside and / or to direct melt that has already escaped back to or into the melting zone.be moved onto the joining surface of the respective profile so that a weld bead does not even form during the subsequent joining process.

[0013] One problem that arises here is contamination of the melt, for example, with dirt particles that may have accumulated on the profile edge layer during storage, as well as melted material from the protective films. These films are located on the visible surfaces of the profiles and serve to protect against transport damage and the effects of building materials. In the more recent state-of-the-art solutions, they are locally removed in an additional step before the melting step.

[0014] Despite these additional measures, a gap often remains between the respective limiting element and the profile part through which melt can flow, making it difficult to reliably prevent the formation of weld beads. After cooling, any weld beads that appear must therefore still be removed in an additional work step. This means that the manufacturing effort and costs cannot be reduced to the desired extent.

[0015] DE 10 2018 133 638 A1 discloses a device and method for welding two plastic profile bars. After the profile bars have been provided, at least one profile bar is machined, particularly in its miter area, with a parting knife. Before heating, the profile bar is machined by a milling cutter, particularly a face milling cutter. This involves heating the profile bars at least at their miter surfaces, and finally, bringing the miter surfaces of the profile bars together so that the heated areas of the miter surfaces create a material-to-material connection between the profile bars.

[0016] EP 3 403 809 A1 discloses a method for welding at least two profiles to form a frame part. The welding surfaces of the profiles are heated by a heating unit. A relative movement occurs between the heating surface and at least one welding surface in a welding plane that runs essentially parallel to the at least one welding surface.

[0017] EP 3 403 810 A1 also discloses a method for welding at least two profiles to form a frame. The welding surfaces of the profiles are heated by a heating unit. Furthermore, a pressure unit exerts pressure on the profiles in their respective welding sections, particularly at the interfaces between the profiles and the heating plate.

[0018] EP 0 264 052 A2 discloses a method for welding plastic profiles. Prior to welding, the ends of each plastic profile are profiled to create two sections. The first section has a front end surface that is heated by the welding mirror, while the adjacent second section has a beveled end surface. During welding, a weld bead is intended to form only on the side of the first section, while no weld bead is intended to form on the side of the second section.

[0019] WO 2013 / 132 406 A1 also relates to a method for welding profile elements made of plastic material.

[0020] DE 20 09 992 A1 discloses a plastic welding machine with a vertically adjustable welding plate mounted on a column and associated guides equipped with clamping devices for plastic profiles, which meet at the welding point. A rotatable arm assembly consisting of several arms is mounted on the column, and at the end of each arm there is a welding plate with a different profile.

[0021] DE 10 2015 013 439 A1 relates to a method for welding two hollow profile bars made of plastic to form a window frame, in which the profile bars to be joined together are heated to a predetermined temperature by inserting a welding mirror between their connecting surfaces and pressing them against the welding mirror to form a welding bead and, after removing the welding mirror, are joined together under pressure while simultaneously enlarging the welding bead.

[0022] A disadvantage of the state of the art is that possible impurities on the profile surface are still present on the surface during the melting process and can enter the melt and thus into the joining zone, which has a detrimental effect on the corner strength of the joint and the appearance of the subsequent window or door frame.

[0023] Against this background, the invention is based on the object of providing a method and a device by means of which the corner strength of the joined profiles can be increased. Furthermore, the appearance of the joining area of ​​the door or window frame or sash is to be further improved.

[0024] This object is achieved by a method according to claim 1 and a device according to claim 11.

[0025] First, at least two profiles are prepared, which are then joined together at the joining surfaces of the profile ends. The heating unit with at least two heating elements is positioned between the profile ends to be joined.

[0026] For an attractive appearance and high corner strength, the visible surfaces must be machined at the miter cut. To do this, the profile ends are chamfered; in particular, a profile edge layer, such as the decorative / protective film or other contaminants, e.g., from transport and storage, is removed in this area. This is done by at least one tool arranged on the heating elements of the heating unit, in particular by means of at least one cutting blade. For this reason, the heating unit has at least two heating elements, each of which has a tool, e.g., a cutting blade.

[0027] Removing the profile edge layer with its contaminants and / or the decorative / protective film is therefore important to achieve optimal strength of the welded joint. The decorative / protective film can lead to non-adhesion of the profile ends during the joining process. Contaminants can also cause particles / substances to become embedded in the melt, which can be detrimental to the welded joint.

[0028] In particular, for the safe removal of the decorative / protective film, the removal depth on the profile, viewed in the miter direction, can be equal to at least the final melting distance during the melting process. The residual compression dimension, however, can remain unprocessed.

[0029] The geometry of the mechanically removed chip is designed as a bevel (chamfer). This has the advantage that less material is removed, which increases corner strength because more material volume is available. It also better directs the flow of the melt in the required direction during the melting process, i.e., into the profile interior or profile chambers.

[0030] After chamfering, i.e. the removal of the profile edge layer, the profile ends to be joined are fed to the heating unit and melted at their later joining surfaces by means of at least one heating surface arranged on the heating elements.

[0031] The melting step refers to the pressing of the profiles against the heating element, e.g. a heating mirror, whereby the material of the profile at the joining surface is melted or melted by the heating. The profile becomes shorter by the so-called burn-off, i.e. the material of the profile that becomes liquid or pasty and moves sideways under the influence of the pressure. Because the joining surface of the profile is pressed against the usually flat heating element, any unevenness on the joining surface of the profile is smoothed out or even compensated for. The melt that moves sideways overflows the separating edge in the areas where a limiting element is in contact with and / or rests on the outer surface of the profile and cools there faster than at the joining surface. This portion of the melt that is not required to create the weld is referred to as melt excess.

[0032] In the case of profiles with colored foil or laminate, the excess melt that escapes, particularly on the visible surfaces, can contain not only the base material of the profile but also components from the melted decorative film or decorative layer. This can contain various materials whose properties may differ from the base material of the profile. The base material of the profile is usually a thermoplastic, such as PVC, while that of the decorative film or decorative layer is sometimes made of other plastics. A decorative film can, for example, consist of a pigmented and / or ink-coated semi-rigid PVC film, which can be laminated with a transparent acrylic film for weather protection.

[0033] In addition, the excess melt may contain portions of melted protective film. The protective film may be made of a different material, such as LDPE, and is removably attached to the profiles using an adhesive. In addition, the production, transport and / or storage of the profiles may result in contaminants such as dust and dirt particles, which can get into the joining surface. The profiles are usually largely covered with protective film on their visible surfaces to prevent damage to the profiles and the workpieces made from them during transport and installation. The protective film usually extends into the area of ​​the excess melt unless it has been removed in a previous work step.

[0034] In order to avoid this mixing of the protective or decorative film and / or impurities with the excess melt, which is detrimental to the corner strength, the profile is chamfered in a preceding process step; in particular, the profile edge layer of the profile ends is preferably removed along their visible surfaces at least up to the melting path.

[0035] A particular advantage of the invention is that the impurities contained in the excess melt, as well as in the melt portions that have already cooled down significantly and are now only present as a doughy mass, are no longer mixed with the melt required for the actual joining. This achieves a high quality weld. Studies have shown that this method can significantly increase the strength values ​​of corner joints compared to conventional corner joints, where a weld bead is also to be avoided. Complex post-processing, especially on the visible surfaces of the profiles, can thus be reduced to a minimum or even completely avoided. This is even possible without prior local removal of the protective film.

[0036] After melting, the heating elements are moved in such a way that the melting material is displaced into the interior of the profile or into the interior of the profile chambers in order to ensure an attractive appearance of the joint.

[0037] A key feature of the invention is that the heating unit is divided into several parts, as this allows the melt to be easily displaced from the visible surfaces inward into the profile chambers. Within the scope of the invention, it is also conceivable for the heating element to be divided into several parts, i.e., to consist of more than two parts, in order to direct even more melt into the interior chambers in a targeted manner, e.g., from front to back, from back to front, from top to bottom, and from bottom to top.

[0038] After removing the heating unit between the profile ends to be joined, shaped strips can be inserted between the limiting knives to reshape and / or displace the melt. The shaped strips serve to deform the profile edge, which is beneficial for the appearance and also compensates for profile tolerances. They also prevent melt from escaping upward from the layer surface during the joining process.

[0039] Using a profile strip, the profile edge of the respective profile, which borders the joining surface on the outside, can be deformed inward, at least in sections, toward the joining surface. This imposes an "alignment" on the profile edge, i.e., the edge of the joining surface, into which it is displaced during the subsequent joining step and the resulting upsetting. During upsetting, the profile edge moves inward toward the joining surface, creating a so-called "shadow groove" or V-groove almost automatically at the joint, simultaneously counteracting any visible leakage of base material that may be present under the paint layer on the profile surface. Any existing height differences between the joined profile parts can be concealed or visually compensated in this way.

[0040] Using the molding strips, the type and extent of post-processing can be adapted as needed. It is also conceivable for the molding strips to process both profiles simultaneously.

[0041] In principle, processing using the shaped strips can be carried out in such a way that the respective profile edge of the profiles is deformed using the shaped strip before the joining step, and a shape is imprinted on the joining line resulting from the weld seam during or after the joining step. In this case, the shaped strip can be moved towards the ends of the profiles to deform the profile edges. The shaped strip can then be left in this position while the profile ends are moved towards each other during the joining step and compressed to form the weld. The shape imprinted on the resulting joining line results from the shape of the processing surfaces of the shaped strip, which are connected to the profile during the compression.

[0042] However, it is also conceivable for the processing to be carried out in two stages using the shaped strips. In particular, it can be provided that the post-processing takes place in such a way that the respective profile edge of the profiles is deformed using a shaped strip in a first processing stage before the joining step. In a second processing stage, which takes place during or after completion of the joining step, i.e. the upsetting, a shape can be imprinted on the joining line resulting from the weld seam using a shaped strip. For this purpose, the shaped strip can be retracted and moved towards the joint again. For example, a V-shaped groove can be imprinted here.

[0043] The shaped strip can be used to limit the flow of molten material toward the visible surface during the joining step. This can be used, for example, to imprint a specific shape on the joining line resulting from the weld seam, such as the aforementioned V-shaped groove.

[0044] Finally, the profile ends are compressed against each other to join the profiles. In other words, in a single joining step, the profiles are pressed against each other with their molten joining surfaces until the melt cools and solidifies, forming a welded joint.

[0045] The area or point to which the profile is melted is also referred to as the melting end point. Since the upsetting process also begins at this point during the joining step, this same area is also referred to as the start of the upsetting path. Set back from this point in the joining or upsetting direction is the so-called joining end point or the end of the upsetting path. During upsetting, the respective profile is shortened to the joining end point.

[0046] The process according to the invention therefore serves, on the one hand, to increase the corner strength of the joined profiles and, on the other hand, has a positive effect on the appearance of the visible surfaces resulting from the melting and compression process. The decorative / protective film does not have to be laboriously removed manually before the joining process.

[0047] According to a first advantageous embodiment of the method according to the invention, a relative movement between each heating element and at least one joining surface is carried out in a joining plane that is substantially parallel to the at least one joining surface. This has the advantage that the melting path is not altered by the relative movement of the heating mirror across the entire miter surface; in particular, the contact between the joining surface and the heating element is not lost.

[0048] Preferably, the two heating elements of the heating unit are moved and positioned horizontally and / or vertically. In particular, the two heating elements are moved toward each other and / or in the direction from the inner to the outer corner of the joined profiles. In other words, the two heating elements are moved toward each other and backward. In a design in which the heating mirror unit has two heating elements, each part of the two heating elements can be moved vertically by means of a motor. The entire heating mirror unit can be moved horizontally by means of a motor. These movements can be superimposed and thus interpolated using a control system.

[0049] According to another embodiment, it is possible for each heating element to have at least two heating surfaces, each of which is assigned to a joining surface of a profile end to be joined. In this way, the two miter surfaces to be joined can be machined simultaneously.

[0050] According to an advantageous development of the invention, the horizontal and / or vertical movement of each heating element is controlled independently of one another. The profiles can be designed differently on the top and bottom sides, so that each side can be processed individually thanks to the independent control of each heating element. If necessary, profiles can also be processed on one side only. The independence of the movements increases the possibilities and thus the flexibility of the device.

[0051] According to a further advantageous embodiment of the method, a cutting blade, preferably with multiple cutting edges, is arranged on each heating element, with a lower cutting blade being assigned to the lower visible surface of the profile end and an upper cutting blade being assigned to the upper visible surface. The advantage of this arrangement is, on the one hand, that the cutting blades are heated via the heating elements, so that cutting works better and easier. Furthermore, it has a cost advantage, because the prior art requires motors to move the heating unit and the heating elements to generate the relative movements. Separate motors are also required for the cutting blades to chamfer the profile contour. Because a cutting blade is arranged on each heating element, the device is more compact and cost-effective, as no separate motors are required for the cutting blades.

[0052] According to a further variant of the invention, the removal depth of the removed coating or profile edge layer on the profile, viewed in the miter direction, is at least equal to the final melting distance during the melting process. The residual compression depth can remain unprocessed. This is because only the coating or decorative / protective film on the visible surface is removed up to the end of the melting distance. The remaining part of the burn-off, the joining distance or compression distance, is left unchanged or removed as little as possible. This minimizes material removal to avoid unnecessarily weakening the strength of the corner joint.

[0053] In a further development of the invention, it is provided that the profile edge layer is removed up to a separation area line and a joining end point line marks the area up to which the profile is compressed at its profile wall during the joining step and the profile is melted up to a melting end point line and wherein the separation area line and the melting end point line or the separation area line and the joining end point line coincide or the separation area line lies between the melting end point line and the joining end point line.

[0054] In a further development of the invention, the cutting blade is heated, in particular by means of the heating unit. This eliminates the need for additional components to heat the cutting blades, and the heating unit can be used multiple times: for melting the profile ends and for heating the cutting blades.

[0055] The profile strip can be positioned between the limiting knives before the profile ends are swaged. This ensures that no material penetrates to the outside. In the final stage, i.e., after the swaging process is complete, the profile strip itself can even be slightly displaced upwards or downwards relative to the limiting knives in the case of the upper visible surface. This ensures a clean finish of the visible surface in the miter area.

[0056] Shortly before the start of upsetting, the molding strips can be inserted between the limiting knives to prevent the molten plastic from penetrating outwards at the joining zones. On the other hand, the unprocessed upsetting dimension is formed inwards by the shaping of the molding strips, which leads to the actual final result of the visible surface appearance.

[0057] In a further development of the invention, the heating elements are equipped with coated, preferably Teflon-coated, grooved and / or toothed heating plates, in particular on both sides, in order to convey the molten plastic mass, which forms between the tooth gaps or the roughened surface during the melting process, in a defined direction, ie into the profile interior or the profile chambers, during the heating mirror movements.

[0058] According to an independent aspect of the invention, a frame is provided, in particular a window frame or door frame, which has profile parts welded together, characterized in that at least one of the welded joints is produced according to a method described above.

[0059] The device proposed according to the invention according to claim 11 for welding at least two profiles for window or door frames can be designed in particular for producing profile parts consisting of thermoplastic plastic to form door or window frames or sashes.

[0060] The device according to the invention can also be designed in such a way that the heating elements can be moved and positioned horizontally and / or vertically by means of servo motors, in particular that the two heating elements can be moved relative to one another and / or in the direction from the inner to the outer corner and / or from the outer to the inner corner of the joined profiles.

[0061] According to the invention, it has proven advantageous if a cutting blade with preferably several cutting edges is arranged on each heating element, wherein a lower cutting blade is assigned to the lower visible surface of the profile end and an upper cutting blade is assigned to the upper visible surface.

[0062] At least one forming strip for shaping the melt can be inserted between the limiting knives. Furthermore, it is conceivable for the forming strips to be designed for simultaneous processing of the two profiles to be joined. This facilitates time-saving, synchronous processing of the profile ends. Furthermore, the forming strips can be moved with a single drive.

[0063] Preferably, the shaped strip can have a processing surface that can be brought into contact with the profile part and that extends at least partially at an angle of greater than 0° to the joining surface. This allows for a more gentle and controlled deformation of the profile edge after the separation step.

[0064] Furthermore, it is possible to design the shaped strip with at least one second processing surface, which adjoins the first processing surface and runs at a different angle to the joining surface. Such a design enables particularly gentle and targeted processing of the profile ends or the weld seam before and during the joining step.

[0065] Further objects, advantages, features, and possible applications of the present invention will become apparent from the following description of an exemplary embodiment with reference to the drawing. All described and / or illustrated features, individually or in any meaningful combination, constitute the subject matter of the present invention, regardless of their summary in the claims or their reference to one another.

[0066] They show schematically: Fig. 1 a perspective view of the device according to the invention, Fig. 2 a sectional view of the device according to the invention in a first position before removing a profile edge layer, Fig. 3 a sectional view of the device according to Fig. 2 in a further position when removing the profile edge layer, Fig. 4 a detailed view according to Figure 3 , Fig. 5 a sectional view of the device according to Fig. 1 in a further position at the beginning of the melting process, Fig. 6 a sectional view of the device according to Fig. 5 in another position at the end of the melting process, Fig. 7 a detailed view according to Figure 6 , Fig. 8 a sectional view of the device according to Fig. 5 in a further position at the end of the melting process and open table supports, Fig. 9 a sectional view of the device according to Fig. 1with a molding shortly before the start of the upsetting process, Fig. 10 a sectional view of the device according to Fig. 9 when the upsetting process has already begun, Fig. 11 a sectional view of the device according to Fig. 9 in a further position at the end of the upsetting process, Fig. 12 different configurations of a groove, Fig. 13 a sectional view of the device according to Fig. 2 in two further positions during removal of the profile edge layer and Fig. 14 a perspective view of a further embodiment of the device according to the invention according to Figure 1 with molding.

[0067] In the following figures of the drawings, identical or equivalent components are provided with reference numerals based on several embodiments in order to improve readability.

[0068] The present invention relates to a method and a device 10 in the form of a welding machine for welding at least two profile parts or profiles 1 for window or door frames or sashes. Figure 1 as well as in Figure 14 An overview of the device 10 is shown, in which the profiles 1 to be joined can be seen, which are opposite each other with their joining surfaces 26, 27. The respective process steps are generally carried out on both profiles 1 simultaneously.

[0069] The profile 1 in the present case is a profile element 1 made of thermoplastic material, e.g., PVC, for producing a window or door sash. The profile 1 is designed as an extruded profile with several parallel, transverse, and obliquely extending profile walls 28, the outermost border of which forms the profile edge 29. The profile 1 has, on the one hand, the lower 17 and the upper visible surface 18, and, on the other hand, functional surfaces that form the outer surfaces of the profile 1. The visible surfaces 17, 18 are the surfaces visible to the outside when the window or door is fully assembled. The functional surfaces are those surfaces required for the various functions of the window sash, such as the overlap that seals the window against the window frame, the support surface that supports a window pane inserted into the window, and other functional surfaces on which, for example, pane seals are arranged.

[0070] Profile 1 is first cut to the profile cutting length, which is longer than the final dimension required for the joined profile 1 by the so-called burn-off.

[0071] Especially in the Figure 1 and the Figure 14 The so-called positioning step, which can be part of the method according to the invention, is shown schematically. During this positioning step, the respective profile 1 is pressed with its joining surface 26, 27 against a stop surface (not shown) of a profile stop in order to align the joining surface 26, 27 with the stop surface. The positioning of both profiles 1 can take place simultaneously if they are pressed against the stop surfaces of the profile stop in order to align the respective joining surfaces 26, 27 with respect to the profile stop and thus with a heating unit 4, as well as with each other.

[0072] After the profile part 1 is aligned with the profile stop, the profile 1 is clamped so tightly on the profile support 30 that no significant movement can occur between the profile 1 and the profile support 30 in the following steps.

[0073] According to Figure 1 and Figure 14 At least one limiting element in the form of a limiting knife 15 is arranged on the profile support 30, which is fixed to the outer surface of the profile part 1, here on the lower Figure 2 concealed visible surface 17, and thereby borders on the joining surface 26, 27 of the profile 1.

[0074] The device 10 also has a heating unit 4 with at least two heating elements 5, 6, which are designed as heating mirrors, as shown in the Figures 1 to 8The two heating elements 5, 6 of the heating unit 4 can be moved and positioned horizontally and / or vertically by means of a servo motor 25, in particular the two heating elements 5, 6 can be moved towards each other and / or in the direction from the inner to the outer corner and / or from the outer to the inner corner of the joined profiles 1, as can be seen from Figure 1 The horizontal and / or vertical movement of each heating element 5, 6 can be controlled independently.

[0075] A relative movement is carried out between each heating element 5, 6 and at least one joining surface 26, 27 in a joining plane F which is substantially parallel to the at least one joining surface 26, 27, as in particular Figure 2 clarified.

[0076] Each heating element 5, 6 has at least two heating plates or heating surfaces 23, 24, each of which is assigned to a joining surface 26, 27 of a profile end 2, 3 to be joined. The heating elements 5, 6 can be equipped with coated, preferably Teflon-coated, grooved, or toothed heating surfaces 23, 24, in particular on both sides.

[0077] As can be seen from the Figures 1 to 4 and 14 , in particular the corresponding detailed views, a tool, in this case in the form of a cutting blade 7, 8 with preferably several cutting edges 16, is arranged on each heating element 5, 6, wherein a lower cutting blade 7 is assigned to the lower visible surface 17 of the profile end 2, 3 and an upper cutting blade 8 is assigned to the upper visible surface 18. The cutting blades 7, 8 can be heated in particular by means of the heating unit 4, which is the case in the present embodiment of the invention.

[0078] By means of these cutting knives 7, 8, the visible surfaces 17, 18 are machined at their respective profile edge layer 20, i.e. the profile ends 2, 3 are chamfered, preferably at least in the melting path along their visible surfaces 17, 18, and a chamfer is created towards the visible surface 17, 18. The outer profile edge layer 20 of the profile 1 is thus removed. By this removal of material in the visible surface area of ​​the profile 1, the material of the outermost profile edge layer 20 in the area of ​​the visible surface 17, 18, which material is detrimental to the corner strength, is removed. The profile edge layer 20 can additionally contain the protective film or the decorative film of the profile 1 itself. Figure 2 shows the profile edge layer 20 in a detailed view.

[0079] Furthermore, tests have shown that even with profiles 1 without any protective and / or decorative films, particles or components are present on or in the profile edge layer 20 in the area of ​​the visible surface 17, 18, which are extremely detrimental to the corner strength of the joined profiles 1. These can be, for example, necessary means of PVC profile extrusion, contamination from storage and / or transport, or the like. Furthermore, experience shows that profile surfaces cut immediately before joining achieve significantly higher corner strength values ​​than untreated surfaces.

[0080] For this reason, it is advantageous to remove only the outer profile edge layer 20 of profile 1. This ensures that as much material as possible is retained on profile 1, i.e., it is not removed, so that the corner strength is not impaired.

[0081] As from Figure 13.1As can be seen from FIG. 1, the removal depth 19 of the removed coating or the profile edge layer 20 on the profile 1, as seen in the mitre direction 21, ie the separation area line 32, preferably has the same dimension as at least the melting end path 31 during the melting process. Furthermore, other removal depths 19 and thus other separation area lines 32 are also conceivable, for example between the melting end point line 31 and the joining end point line 33, as can be seen from FIG. Fig. 13.2 emerges.

[0082] How Figures 1 to 8 To further clarify, the heating unit 4 with the heating elements 5, 6 is positioned between the profile ends 2, 3 of the profiles 1 to be joined.

[0083] According to Figures 3 and 4, in particular the corresponding detailed views, the chamfering of the profile ends 2, 3 described above takes place along their visible surfaces 17, 18 by means of at least one tool arranged on the heating elements 5, 6 of the heating unit 4, in particular by means of the at least one cutting blade 7, 8.

[0084] The result is the Figure 5 , in particular the detailed view therein, according to which the profile ends 2, 3 are chamfered, in particular at least up to the melting end path 31. As a result, the geometry of the mechanically removed chip is preferably designed as a slope, i.e., a chamfer. This has the advantage, on the one hand, that less material is removed, which leads to an increase in corner strength, since more material volume is available. On the other hand, the flow direction of the melt 9 is better guided in the necessary direction during the melting process, i.e., into the profile interior 11 or into the interior 12 of the profile chambers 13.

[0085] After chamfering, the profile ends 2, 3 to be joined are fed to the heating unit 4, as shown in the Figures 5 to 8 is shown.

[0086] Figure 5 shows the beginning, the Figures 6 and 7 the end of melting and the Figure 8 The end of the melting process with the profile supports 30 already opened. During the melting process, the joining surface 26, 27 of the profile 1 is pressed against the heating surfaces 23, 24 of the heating unit 4 in order to melt the profile 1 at its joining surface 26, 27. For this purpose, the respective profile supports 30 can be moved towards the heating unit 4, which was moved between the joining surfaces 26, 27 of the profile parts 1 after the profile stop was removed.

[0087] Essential in the present invention is according to Figures 5 to 8that the heating unit 4 is divided into several parts. This is because the heating elements 5, 6 move in such a way that the melt 9 is displaced into the profile interior 11 or into the interior 12 of the profile chambers 13 of the profiles 1. In this way, the melt 9 can be moved in a controlled manner from the visible surfaces 17, 18 inwards into the profile chambers 13. Within the scope of the invention, it is also conceivable for the heating unit 4 to consist of more than two heating elements in order to direct even more melt 9 into the inner chambers 12 in a targeted manner, for example from front to back, from back to front, from top to bottom and from bottom to top.

[0088] The melting process comprises the initial melting of the profile 1 to the melting point, and post-heating, i.e., remaining at the melting point to generate deep heat, i.e., heating the material to be compressed. In this case, both are combined in the melting process, which is used to displace the melt material 9 into the profile interior 11 or into the interior 12 of the profile chamber 13.

[0089] Furthermore, in Figures 3 and 5 the melting end path or the melting end point line 31 is drawn, which indicates the area up to which the heating unit 4 penetrates into the material of the profile 1 during the melting process. The material melted in the process escapes as melt excess or melt material 9 and is displaced into the profile interior 11 in a controlled manner by the heating mirror movements. Figure 3 shows the cutting process and Figure 5 the insertion of the heating unit 4.

[0090] Furthermore, Figure 3the separation area line 32 between the melting end path or the melting end point line 31 and the joining end point line 33 is drawn. The separation area line 32 indicates the point up to which the profile edge layer 20 is removed. The joining end point line 33 indicates the area up to which the profile 1 is compressed at its profile wall 28 during the subsequent joining step. The method can also be modified in such a way that the separation area line 32 and the melting end point line 31 coincide or that the joining end point line 33 and the separation area line 32 coincide. However, the Figure 2 arrangement shown, in which the separation area line 32 is provided closer to the melting end point line 31 than to the joining end point line 33.

[0091] Furthermore, in the Figures 9 , 10 and 11a shaped strip 14 acting as a finishing tool is shown. As mentioned, the melt 9 produced by the melting process is displaced into the profile interior 11 by the heating mirror movements. The shaped strip 14 is intended to prevent heated material from being pushed outwards during the compression of the profiles 1. Figure 14 the molding 14 can also be seen.

[0092] First, a controlled displacement of the melt excess or the melt material 9 into the profile interior 11 takes place using the multi-part heating unit 4. The heating elements 5, 6 are moved in such a way that the melt material 9 is displaced into the profile interior 11 or into the interior 12 of the profile chambers 13 of the profiles 1.

[0093] After the melt 9 has been shifted inwards, which is in the Figures 9 to 12As shown, the two profile parts 1 can be machined using a shaped strip 14. In the present example, a two-stage post-processing is carried out, in which, during the upsetting process, the respective profile edge 29 is impressed with a direction of movement directed inwards towards the joining surface 26, 27, so that during the subsequent joining a V-groove is produced between the profile parts 1 in the area of ​​the weld. Figure 12 with its detailed views shows different designs of this V-groove.

[0094] During the forming and / or displacement of the melt 9 by means of the forming strip 14, the profile ends 2, 3 can be compressed against each other to join the profiles 1. It is also conceivable to compress the profile ends 2, 3 against each other without forming and / or displacing the melt 9 by means of the forming strip 14.

[0095] Figure 9 shows the device shortly before the start of the upsetting process, Figure 10an intermediate position and Figure 11 the end of the compression process.

[0096] Figure 10 , in particular the detailed view, shows that the contour, ie the bevels of the molding 14, touch the limiting blade 15, in particular its contour, ie the bevels, and thus close the path of the melt 9 to the outside. The design of the V-groove of the connection can be adjusted via the position, or more precisely the distance A, which can be adjusted independently of the profile supports 30, of the limiting blade 15 at the upsetting end, as can be seen from Figure 12 The larger the distance A at the end of the upsetting process, the larger the gap between the limiting blades 15. In this way, the shaped strip 14 is pushed less over the bevels of the limiting blade 15 outside the connection and the shaped strip 14 can remain deeper in the joining plane F, so that a larger V-groove can be realized, as can be seen from Figure 12.3With a distance A of zero between the limiting blades 15, the shaped strip 14 is pushed completely out of the profiles 1 and no V-groove is formed, as Figure 12.1 shows. The Fig. 12.2 shows an intermediate position.

[0097] The Figure 9 shows the position shortly before the start of joining or upsetting the profiles 1. The shaped strip 14 is positioned above or below the visible surface 17, 18 and is pushed up / down by the upsetting process via the bevels or undercut of the limiting blade 15. Thus, the area for the melt 9 is already blocked to the outside by the shaped strip 14, and no melt 9 can penetrate to the outside during the joining process.

[0098] The fact that the molten material cannot escape from the visible surface 17, 18 during joining / upsetting is ensured by two measures, one in the melting process and one in the upsetting process.

[0099] During the melting process, the heating unit 4 and its movements during the melting process move the melting material 9 in a controlled manner into the interior 12 of the profile chambers 13. To ensure that no contaminants from the area of ​​the visible surfaces 17, 18 can enter the melting material 9, material and thus possible contaminants are removed from the surface of the profile 1 in the joining area.

[0100] Furthermore, the contour of the forming strip 14 can shape the heated material between the melting end point and the joining end point during the upsetting process and, at the same time, it can prevent the melt 9 from escaping to the outside due to the positive engagement of the bevel of the forming strip 14 with the bevels of the limiting knives 15 and, depending on the limiting knife position at the upsetting end, contribute to the shaping.

[0101] The limiting blade 15 can be guided under spring preload toward the joining surface 26, 27 in order to form the narrowest possible gap between the heating surface 23, 24 and the separating edge during the melting step. The limiting blade 15 can also be supplemented in its function by the shaping strip 14, which reduces the outward leakage of the melt material 9 during the melting step. At the same time, the shaping strip 14 can be flush with the joining plane F.

[0102] Protective films present on the visible surfaces 17, 18, which are not shown here for the sake of simplicity, can remain on the profile 1 without prior processing and do not, or only insignificantly, impair the aesthetics and mechanical strength of the joint created according to the invention. List of reference symbols

[0103] 1 Profile 2 Profile end 3 Profile end 4 Heating unit 5 Heating element 6 Heating element 7 Tool / cutting blade 8 Tool / cutting blade 9 Melt material 10 Device 11 Profile interior 12 Profile chamber interior 13 Profile chamber 14 Molding strip 15 Limiting blade 16 Cutting 17 Lower visible surface 18 Upper visible surface 19 Removal depth 20 Profile edge layer 21 Miter direction 23 Heating surface 24 Heating surface 25 Servo motor 26 Joining surface 27 Joining surface 28 Profile wall 29 Profile edge 30 Profile support 31 Melting end path or melting end point line 32 Separation area line 33 Joining end point line F Joining plane A Distance between the limiting blades

Claims

1. Method for welding at least two profiles (1) for window frames or window casements, or door frames or door leaves, comprising the following steps: - providing at least two profiles (1) which will be connected to one another at joining surfaces (26, 27) of the profile ends (2, 3), - positioning a heating unit (4) with at least two heating elements (5, 6) between the profile ends (2, 3) to be joined, - bevelling, in particular removing material from, a profile edge layer (20) of the profile ends (2, 3), preferably at least as far as the melting path, along their visible surfaces (17, 18) by means of at least one tool arranged on the heating elements (5, 6) of the heating unit (4), in particular by means of at least one cutting blade (7, 8), - advancing the profile ends (2, 3) to be joined to one another to the heating unit (4), - incipiently melting the profile ends (2, 3) at what will be their joining surfaces (26, 27) by means of at least one heating surface (23, 24) arranged on the heating elements (5, 6), - moving the heating elements (5, 6) in such a way that the molten material (9) is displaced into the profile interior (11) or into the interior (12) of the profile chambers (13) of the profiles (1), - removing the heating unit (4) between the profile ends (2, 3) to be joined, and - compressing the profile ends (2, 3) against one another such that the profiles (1) are joined to one another.

2. Method according to Claim 1, characterized in that a relative movement between each heating element (5, 6) and at least one joining surface (26, 27) is performed in a joining plane (F) which is substantially parallel to the at least one joining surface (26, 27).

3. Method according to Claim 1 or 2, characterized in that the two heating elements (5, 6) of the heating unit (4) are moved and positioned horizontally and / or vertically, in particular in that the two heating elements (5, 6) are moved relative to one another and / or in the direction from the inner corner to the outer corner, and / or from the outer corner to the inner corner, of the joined profiles (1).

4. Method according to one of Claims 1 to 3, characterized in that each heating element (5, 6) has at least two heating surfaces (23, 24), each of which is assigned to a joining surface (26, 27) of a profile end (2, 3) to be joined.

5. Method according to one of the preceding claims, characterized in that the horizontal and / or the vertical movement of each heating element (5, 6) is controlled in a mutually independent manner.

6. Method according to one of the preceding claims, characterized in that, on each heating element (5, 6), there is arranged in each case one cutting blade (7, 8) with preferably multiple cutting edges (16), wherein a lower cutting blade (7) is preferably assigned to the lower visible surface (17) of the profile end (2, 3) and an upper cutting blade (8) is preferably assigned to the upper visible surface (18).

7. Method according to one of the preceding claims, characterized in that the material-removal depth (19) of the coating or profile edge layer (20) on the profile (1) subjected to material removal, when viewed in the mitre direction (21), has at least the same dimension as the end-of-melting path (31) in the melting process.

8. Method according to one of the preceding claims, characterized in that material is removed from the profile edge layer (20) as far as a separation region line (32), and a joining end point line (33) indicates the region as far as which the profile (1) is compressed at its profile wall (28) during the joining step, and the profile (1) is incipiently melted as far as a melting end point line (31), and wherein the separation region line (32) and the melting end point line (31) or the separation region line (32) and the joining end point line (33) coincide or the separation region line (32) is between the melting end point line (31) and the joining end point line (33).

9. Method according to one of the preceding claims, characterized in that the cutting blade (7, 8) is heated, in particular by means of the heating unit (4).

10. Method according to one of the preceding claims, characterized in that the heating elements (5, 6) are provided with coated, preferably Teflon-coated, corrugated and / or toothed heating plates (23, 24), in particular on both sides.

11. Device (10) for welding at least two profiles (1) for window frames or window casements, or door frames or door leaves, in particular for carrying out a method according to one of Claims 1 to 10, having a heating unit (4) which is introducible between the profile ends (2, 3) to be joined and has at least two heating elements (5, 6) for incipiently melting the profile ends (2, 3) at what will be their joining surfaces, wherein, for bevelling, in particular removing material from, a profile edge layer (20) of the profile ends (2, 3) along their visible surfaces (17, 18), provision is made of at least one tool, in particular at least one cutting blade (7, 8), which is arranged on the heating elements (5, 6) of the heating unit (4), wherein the heating elements (5, 6) are movable in such a way that the molten material (9) is displaced into the profile interior (11) or into the interior (12) of the profile chambers (13), wherein provision is made of a compression device for compressing the profile ends (2, 3).

12. Device (10) according to Claim 11, characterized in that the heating elements (5, 6) are horizontally and / or vertically movable and positionable by means of servomotors (25), in particular in that the two heating elements (5, 6) are movable relative to one another and / or in the direction from the inner corner to the outer corner, and / or from the outer corner to the inner corner, of the joined profiles (1).

13. Device (10) according to Claim 11 or 12, characterized in that, on each heating element (5, 6), there is arranged in each case one cutting blade (7, 8) with preferably multiple cutting edges (16), wherein a lower cutting blade (7) is preferably assigned to the lower visible surface (17) of the profile end (2, 3) and an upper cutting blade (8) is preferably assigned to the upper visible surface (18).

14. Device (10) according to Claims 11 to 13, characterized in that the heating elements (5, 6) are provided with coated, preferably Teflon-coated, corrugated or toothed heating surfaces (23, 24), in particular on both sides.

15. Device (10) according to one of Claims 11 to 14, characterized in that the tool (7, 8) is heated, in particular by means of the heating unit (4).