Device and method for joining plastic profiles

Abstract

Device (1) for connecting a first plastic profile (6) to a second plastic profile (6') at their connecting surfaces (60, 60'), wherein the device (1) a first clamping device (2) for holding and positioning the first plastic profile (6) and a second clamping device (2') for holding and positioning the second plastic profile (6'), wherein at least one of the clamping devices (2, 2') is movable so that the plastic profiles (6, 6') can be moved towards and away from each other; a heating device (5) that can be positioned between the connecting surfaces (60, 60') for at least partially melting at least one of the connecting surfaces (60, 60'); at least one pressing device (3, 3') at least for pressing the connecting surfaces (60, 60') against the heating device (5) and for pressing the plastic profiles (6, 6') against each other; and a cleaning mechanism (7) for removing a weld bead formed when joining the plastic profiles (6, 6'); characterized by that the device (1) has, in addition to the pressing device (3, 3'), at least one pressing device (4, 4') for pressing the plastic profiles (6, 6') against each other, wherein the technical operating principle of the pressing device (4, 4') differs from the technical operating principle of the pressing device (3, 3') and a higher force can be exerted on the plastic profiles (6, 6') by the pressing device (4, 4') than by the pressing device (3, 3').

Description

[0001] The present invention relates to a device for connecting a first plastic profile to a second plastic profile at their connecting surfaces, wherein the device has a first clamping device for holding and positioning the first plastic profile and a second clamping device for holding and positioning the second plastic profile, wherein at least one of the clamping devices is movable so that the plastic profiles can be moved towards and away from each other; a heating device positionable between the connecting surfaces for at least partially melting at least one of the connecting surfaces; at least one pressing device at least for pressing the connecting surfaces against the heating device and for pressing the plastic profiles against each other; and a cleaning mechanism for removing a weld bead created when connecting the plastic profiles.

[0002] The present invention further relates to a method for joining a first plastic profile to a second plastic profile at their joining surfaces, wherein the first plastic profile is held in a first clamping device and the second plastic profile is held in a second clamping device; the joining surfaces of the plastic profiles are pressed relative to one another along a travel path and against a heating device positioned between the joining surfaces using at least one pressing device; at least one of the joining surfaces is at least partially melted by the heating device; the heating device is then moved away from the plastic profiles; and thereafter the joining surfaces are pressed against one another using the pressing device and are joined in the process; and a welding bead created when the plastic profiles are joined is removed.

[0003] It is known from the prior art to join plastic profiles to form plastic window or door frames using heated mirror welding. For this purpose, the plastic profiles to be joined are mitered, and the connecting surfaces of the plastic profiles—that is, those surfaces that touch when the plastic profiles are joined—are melted by pressing them against a heated mirror. Heat-treated mirrors are hot-plate-like heating elements suitable for at least partially melting connecting surfaces. The molten connecting surfaces are then pressed against each other, whereby the still-hot, thermoplastic material of the plastic profiles bonds in such a way that a stable weld is created at the connecting surfaces.

[0004] To carry out such a process, the plastic profiles are placed in a device for welding plastic profiles, as described, for example, in the document DE 10 2004 006 421 B4. The device has a stationary table on which one of the plastic profiles is clamped with a clamping device. Furthermore, the device has a work carriage that can be moved horizontally toward the table and supports the second plastic profile. To join the plastic profiles, the work carriage is moved toward the table by means of a pneumatic drive, so that the previously melted plastic profiles can be pressed together under force.

[0005] The disadvantage of this procedure is that the material displaced when the plastic profiles are pressed against each other forms a weld bead along the weld seam, which must be subsequently removed.

[0006] A device for removing weld beads is disclosed, for example, in document DE 20 2012 100 935 U1. The device uses scissors or cutting pliers to remove weld beads.

[0007] The document DE 35 39 670 C2 teaches the removal of welding beads by means of a cutting knife which is guided along the welding bead.

[0008] JP S54-61271 A describes a device for butt welding thermoplastic pipes. The device comprises a rotating cutting device with which opposing ends of the plastic pipes are first cut off. Furthermore, the device comprises a heating plate against which the cut ends of the plastic pipes are pressed by a hydraulic pressing device, thereby melting them and subsequently pressed against each other.

[0009] Document DE 2614208 A1 describes a contact welding device with a contact force that can be programmed and continuously adjusted during the welding process for welding plastic parts. A heating element is first placed between the plastic parts, against which the plastic parts are pressed at their ends by means of cylinders or springs whose preload is adjustable by motors. The cylinders then move apart and the heating element is moved away, whereupon the heated plastic parts to be welded are brought back together by the cylinders and welded.

[0010] Document DD 68071 A1 discloses a device for welding thermoplastic pipes and profiles using the heated element welding process. The butt surfaces of the parts to be joined are heated to welding temperature using a heating element and then joined under pressure. The thermoplastic parts to be welded are clamped in clamping devices arranged so that they can slide along a common guide, and both clamping devices are then moved by the same working cylinder.

[0011] It is the object of the present invention to provide a device and a method for joining plastic profiles, in which a highly stable connection is produced between the plastic profiles and the welding bead can be effectively removed.

[0012] This object is achieved, on the one hand, by a device of the type mentioned at the outset, which, in addition to the pressing device, has at least one pressing device for pressing the plastic profiles against one another, wherein the technical operating principle of the pressing device differs from the technical operating principle of the pressing device and a higher force can be exerted on the plastic profiles by the pressing device than by the pressing device.

[0013] In the description of the present invention, the terms "connecting" and "joining" are used synonymously. The term "technical operating principle" refers to the laws of a technological process that describe the interaction of physical effects, geometric, and material characteristics in a process. In this context, a technical operating principle refers in particular to whether a force is applied mechanically, electrically, hydraulically, or pneumatically.

[0014] The device according to the invention is primarily used for joining plastic profiles that form window and / or door frames, for example. Specifically, the device can be used for joining plastic profiles that form window and door frame corners, which have previously been mitered. Furthermore, the device according to the invention can also be used for producing transoms, arched window or door frames, or other objects made from plastic profiles.

[0015] Plastic profiles are understood here to mean preferably elongated elements which consist predominantly of plastic and have any cross-section, but often essentially rectangular, and a large length compared to the cross-sectional dimensions.

[0016] The device according to the invention comprises at least a first and a second clamping device for receiving the plastic profiles to be joined, in each of which a plastic profile is clamped. The clamping devices are aligned so that the connecting surfaces of the first and second plastic profiles to be joined can be brought into contact with each other. For this purpose, at least the first clamping device is arranged to be movable, so that at least one of the plastic profiles can be moved toward and away from the other.

[0017] To precisely position and connect the plastic profiles to be joined, it is advantageous if the device has at least one positioning aid for positioning the plastic profiles in the clamping devices. The positioning aid can, for example, comprise one or more pin- or plate-shaped positioning elements against which the plastic profiles are placed or clamped. The positioning elements can be movable or fixed on or near the respective clamping device. Furthermore, one positioning element can be used for both clamping devices.

[0018] For a positionally accurate, speed-adapted and yet high-force movement of at least one of the clamping devices with the plastic profile located therein, this is functionally connected to both the pressing device and the pressing device.

[0019] According to the invention, the technical operating principle of the pressing device differs from that of the clamping device, with the pressing device being capable of exerting a greater force on the respective plastic profile in the respective clamping device than the pressing device. The forces exerted by the pressing device and the pressing device differ in such a way that the clamping device can move the plastic profiles toward each other with precise positioning and slowly using the pressing device, while the clamping device can move them toward each other quickly and with high pressure.For joining, the connecting surfaces of the plastic profiles can first be pressed slowly and precisely against the heating device positioned between the connecting surfaces using the pressing device. After the heating device has been moved away, they are pressed against each other with little force. They are then pressed firmly together using the pressing device under the action of a greater force, creating a high-quality, very narrow weld seam. This creates a particularly high corner strength of the welded plastic profiles. In addition, the force exerted by the pressing device can be adjusted to such a high level that the cleaning tools of the cleaning mechanism provided on the clamping devices can immediately shear off the weld bead created during welding, making subsequent feeding of the cleaning tools for cleaning essentially unnecessary.

[0020] Depending on the embodiment of the device according to the invention, the pressing device can be activated either when a certain pressure is reached by the pressing device and / or after a predetermined process time and / or after sensor detection of a predetermined melting status of at least one of the connecting surfaces. For example, the pressing device can be activated just a few milliseconds after the pressing device has pressed against the melted connecting surfaces.

[0021] Preferably, however, the pressing device is only activated after the plastic profiles have traveled a predetermined distance toward each other. For this purpose, the device according to the invention has at least one displacement sensor with which the position of the plastic profiles can be detected.

[0022] The device according to the invention comprises a heating device for melting at least one connecting surface of at least one of the plastic profiles. The heating device is provided on the device so that it can be moved. With regard to the quality and stability of the joint to be formed between the plastic profiles, it is particularly advantageous if both connecting surfaces are melted or at least partially melted by the heating device. For this purpose, the heating device can be brought into direct contact with the at least one connecting surface or can be provided at a distance from the at least one connecting surface to be melted or partially melted. Depending on the embodiment of the device according to the invention, the heating device can be activated and / or deactivated manually or automatically. Furthermore, several heating devices can also be coupled to the device.

[0023] In a particularly preferred embodiment of the device according to the invention, the heating device has a welding plate, by means of which the plastic profiles can be melted particularly quickly and precisely. It has proven advantageous if both plastic profiles are melted or partially melted, for example by pressing a plastic profile against the welding plate on both sides. For this purpose, the welding plate is advantageously designed to be at least as large as the connecting surfaces of the plastic profiles to be joined. Furthermore, the device for melting at least one of the connecting surfaces can also have an infrared heater, a burner, or the like.

[0024] If the device has a welding plate, this is advantageously movable so that it can be brought into contact with at least one of the connecting surfaces of at least one of the plastic profiles. The welding plate is preferably arranged and guided so that it can be moved between the plastic profiles to be joined. The welding plate is preferably moved horizontally between the plastic profiles, but this can also be done vertically or at an angle. When the welding plate is arranged between them, the plastic profiles are pressed against the welding plate by means of an adjustment of the clamping devices and are at least partially melted.After the joining surfaces have been melted, the clamping devices are moved apart again, removing the plastic profiles from the welding plate, allowing the plate to be easily removed from between the two plastic profiles by moving it back. As soon as the welding plate has reached a starting position where it is no longer positioned between the two plastic profiles, the two plastic profiles are pressed together and joined by moving the clamping devices toward each other. Depending on the design, the welding plate can be controlled and moved automatically or manually.

[0025] It has proven particularly advantageous if the welding plate is Teflon-coated, as this prevents the plastic profiles from sticking to the welding plate. However, the welding plate can also have a different non-stick coating.

[0026] In order to remove a weld bead that forms during the joining of plastic profiles, the device according to the invention has a cleaning mechanism. The cleaning mechanism can, for example, comprise at least one blade, a pair of scissors, a pair of cutting pliers, a parting knife, or a cutting knife. The cleaning mechanism can, for example, be provided on one of the clamping devices or on a separate holding device. The cleaning mechanism is used in the device according to the invention directly after the joining process is completed, sometimes even before the joining process is completed.

[0027] It has proven particularly advantageous if the pressing device has a pneumatic cylinder and the pressing device has a hydraulic cylinder, an electromechanical drive and / or a toggle lever. A hydraulic cylinder with a 40 mm diameter is preferably used as the hydraulic cylinder. In suitable embodiments of the invention, a pressure of at least 10 bar can be exerted on the plastic profiles with the pressing device. A servo motor in conjunction with a trapezoidal thread spindle or a ball screw or a planetary roller screw can be used as the electromechanical drive. Racks and pinions can also be used to transmit movement. If a toggle lever is used as the pressing device, relatively little force can be exerted on the plastic profiles at the beginning of the joining process.Only when the toggle lever is fully extended does a correspondingly large force act on the plastic profiles. For example, a pneumatic cylinder with a diameter of 80 mm can be used as the pressure device in the device according to the invention.

[0028] Pneumatic cylinders are advantageously easy to control, especially at low pressures, allowing the clamping device and thus the plastic profile clamped within it to be moved slowly, gently, and precisely. Furthermore, the pneumatic cylinder allows for continuously adjustable speeds at which the plastic profiles move toward and away from each other, as well as the force exerted on the plastic profiles. Pneumatic drives are generally relatively simple in design and therefore more cost-effective than electric drives. In the event of leaks, the escaping fluid does not cause environmental damage. The pneumatic cylinder used is largely insensitive to temperature and robust against overload, making it particularly well-suited for welding plastic profiles.Compared to a hydraulic cylinder, however, the pneumatic cylinder can transmit comparatively small forces and torques, which is why, in the present invention, a pneumatic cylinder is preferably used to begin the joining process between the plastic profiles, where it is important to position the plastic profiles with high precision. Thus, in this preferred embodiment of the invention, the plastic profiles are positioned with the help of the pneumatic cylinder and preferably joined using the hydraulic cylinder under the action of large forces.

[0029] In alternative embodiments of the device according to the invention, a toggle lever device or another drive or mechanism can be used instead of the hydraulic cylinder, allowing a greater force to be exerted on the plastic profiles than the pneumatic cylinder. In other embodiments of the invention, an electric drive or other drive can also be used instead of the pneumatic cylinder.

[0030] It has also proven particularly advantageous if the pressing device and the pressing mechanism are functionally coupled. In particular, if the pressing device is designed as a pneumatic cylinder and the pressing mechanism as a hydraulic cylinder, the pneumatic and hydraulic cylinders can be connected to one another in such a way that the pistons of these cylinders can be moved together. This can be achieved, for example, by mechanically coupling the piston rod. The coupling can also be achieved by forcing hydraulic fluid, such as oil, into or out of the hydraulic cylinder as the air in the pneumatic cylinder compresses and expands.

[0031] Advantageously, by coupling the pneumatic and hydraulic cylinders, the hydraulic fluid required for the hydraulic cylinder's functionality is drawn into or expelled from a cylinder chamber formed by a cylinder tube and a piston while the pneumatic cylinder is being driven. This prevents shocks to the device when the hydraulic cylinder, which acts after the pneumatic cylinder, is activated. Furthermore, comparatively little hydraulic fluid is required to achieve high forces when the hydraulic cylinder is activated.

[0032] It has also proven suitable if a hydraulic fluid inlet and outlet are provided in a cylinder tube of a hydraulic cylinder of the pressure device on both sides of the piston of the hydraulic cylinder, wherein at least the hydraulic fluid inlet and outlet provided on one piston rod side of the hydraulic cylinder is connected to a hydraulic fluid reservoir. The additional hydraulic fluid reservoir provided on the piston rod side of the hydraulic cylinder can prevent ambient air from being sucked into the cylinder tube of the hydraulic cylinder during a piston movement of the hydraulic cylinder caused by the drive of the pneumatic cylinder, since hydraulic fluid is drawn into the cylinder tube at the location of the ambient air. Advantageously, the efficiency of the hydraulic cylinder can be kept constantly high.

[0033] With regard to joining the two plastic profiles, it has proven particularly advantageous if both clamping devices are movable, and the first clamping device is connected to a first of the at least one pressing device and a first of the at least one pressing device, and the second clamping device is connected to a second of the at least one pressing device and a second of the at least one pressing device. This allows for a higher contact force to be generated, and for the plastic profiles to be positioned more flexibly and / or precisely.

[0034] It has also proven practical if the at least one pressing device and the at least one pressing device are provided on guides for the clamping devices. In particular, it is advantageous if the pressing device and the pressing device are arranged at one end of the respective guide, with the pressing device and the pressing device advantageously being provided side by side. In alternative embodiments of the device according to the invention, however, the pressing device and the pressing device can also be attached to other parts of the device, such as, for example, to one of the clamping devices.

[0035] For connecting plastic profiles forming window and / or door frame corners, it is also advantageous if the device has a first and a second guide for guiding the first and second clamping devices, wherein the first and the second guide are aligned, for example, at right angles to one another.

[0036] The vertical arrangement of the guides and thus the clamping devices allows for optimal joining of mitered plastic profiles. The guides are positioned in such a way that at least the plastic profiles to be joined can be easily pressed together. Furthermore, the guides can also be aligned so that individual components of the clamping devices can touch each other, or they can be arranged with only a small distance between them.

[0037] If window or door frames with a non-right-angled corner, but for example with an obtuse-angled corner, arched window and door frames or other objects are to be produced with the device, the guides and the clamping devices can also be arranged at a different angle to each other.

[0038] It has also proven advantageous if the first and second clamping devices are L-shaped, wherein a horizontally aligned leg of the L forms a support surface for each of the plastic profiles and a clamping element that can be moved relative to the support surface is provided on a vertical leg of the L.

[0039] The clamping element, which can be moved vertically in a functionally correct alignment of the fixture, allows plastic profiles of various dimensions to be securely and non-destructively clamped by the respective clamping device. For optimal clamping of the plastic profiles, a force and / or displacement sensor can be installed on the clamping device. Clamping is preferably automatic, but can also be done manually.

[0040] Particularly when the guides guiding the clamping devices are arranged at right angles to one another, it is advantageous if the L-shaped clamping devices are mounted on the guides in such a way that the two horizontally aligned legs of the L-shaped clamping devices extend in the longitudinal direction of the guides, and those sides of the horizontal legs that are not connected to the vertical leg face each other. It has proven advantageous in this case if the support surfaces and the clamping elements have a cross-section that is triangular or convex in plan view, which is adapted to the shape of the mitered plastic profiles to be connected.By designing the support surfaces and clamping elements in this way, the plastic profiles to be connected can be placed almost flush with the support surfaces and / or clamping elements in the clamping devices, whereby the plastic profiles are held particularly stable and large forces can be exerted when connecting them without the plastic profiles bending or even breaking.

[0041] In a further variant of the device according to the invention, the clamping devices can also be C-, U-, T- or I-shaped, for example.

[0042] It has also proven advantageous if the cleaning mechanism has at least four blades, wherein a first blade is arranged on the clamping element of the first clamping device, a second blade on the clamping element of the second clamping device, a third blade on the support surface of the first clamping device and a fourth blade on the support surface of the second clamping device and the blades are aligned such that they run along the welding bead formed during joining and the first and second blades and the third and fourth blades can interact with each other.

[0043] Such a blade arrangement allows the weld bead created when joining the plastic profiles to be cut off immediately when the plastic profiles are pressed against each other and the associated movement of the support surfaces or clamping elements toward each other. The weld bead is simply squeezed between the two blades attached to the support surfaces or between the two blades provided on the clamping elements and cut off. This avoids the subsequent, laborious, time-consuming, and costly removal of the weld bead.

[0044] The high forces that can be applied by at least one clamping device to at least one clamping device not only ensure that the plastic profiles are connected with sufficient pressure, but also that the weld bead is severed smoothly and without residue. However, in variants of the device according to the invention in which a low force is applied to the at least one clamping device, it may also happen that a small part of the weld bead is not severed because the blades cannot be fully moved together.

[0045] To ensure that the entire weld bead can be removed in a single step, it has also proven advantageous for the blades to extend at least over the entire length of the weld bead formed during the joining of the plastic profiles. Furthermore, the blades can also be longer or shorter than the resulting weld bead. In an alternative embodiment of the device according to the invention, several blades can also be attached to a support surface and / or a clamping element.

[0046] Preferably, the blades are arranged on the device in such a way that they can be easily exchanged and replaced with an identical or differently designed blade. This makes it easy to replace blunt blades with sharp ones, so that the cutting process can be carried out as simply and as forcefully as possible. Furthermore, the blades can be easily adapted to different boundary conditions, for example, to different joining materials.

[0047] To ensure that the developing weld bead can be completely severed, it is advantageous if the clamping devices can be moved such that the first and second blades, as well as the third and fourth blades, are spaced apart by a maximum of 0.15 mm when the clamping devices are retracted. Such close proximity of the clamping devices to one another is ensured in particular by the arrangement and design of the clamping device guides and the forces generated by the pressure device.

[0048] It has also proven advantageous if the first and second clamping devices are coupled by means of the pressing device, for example by means of a hydraulic cylinder, on their upper side located opposite the device on the machine table. The hydraulic cylinder can, for example, be attached to the upper ends of the clamping devices in a functionally correct alignment of the devices according to the invention and thus serve to stabilize the clamping devices under load. This prevents the upper ends of the clamping devices from being forced apart, allowing a weld seam of consistently high quality to be produced. The hydraulic cylinder can therefore be used not only to press the plastic profiles against one another, but also to stabilize the device, so that the same forces act on the clamping devices at the top and bottom.

[0049] To withstand the high forces when connecting the plastic profiles, the device preferably has a machine table made of a metal plate at least 10 cm thick. Depending on the application, however, the machine table can also be thicker, for example, it can have a thickness of 20 cm to 30 cm. The machine table can be made of cast iron or steel, for example.

[0050] The object is further achieved by a method for connecting a first plastic profile to a second plastic profile at their connecting surfaces, in which the first plastic profile is held in a first clamping device and the second plastic profile is held in a second clamping device; the connecting surfaces of the plastic profiles are pressed relative to one another by at least one pressing device and against a heating device positioned between the connecting surfaces; at least one of the connecting surfaces is at least partially melted by the heating device; then the heating device is moved away from the plastic profiles; thereafter the connecting surfaces are pressed against one another at least by means of the pressing device and are thereby connected;and subsequently a welding bead created during the joining of the plastic profiles is removed, wherein at least one pressing device is additionally used to connect the connecting surfaces of the plastic profiles, which presses the connecting surfaces of the plastic profiles against one another with a different technical operating principle than that of the pressing device and with a higher force than the pressing device;

[0051] The method according to the invention is primarily used for the production of plastic window and / or door frames with welded corners. However, the method can also be used for joining other objects and materials.

[0052] In the method according to the invention, the plastic profiles to be joined are first inserted into a clamping device and clamped. Subsequently, at least one connecting surface of one of the two plastic profiles is heated or melted, so that a material connection between the plastic profiles is formed by subsequently pressing the connecting surfaces of the plastic profiles together.

[0053] To melt or fuse at least one connecting surface of at least one of the plastic profiles, it has proven effective to melt it by pressing it against a welding plate. Using a welding plate allows heat to be transferred to the respective connecting surface in a targeted and effective manner. However, the welding plate should be at least as large as the connecting surface.

[0054] Preferably, the at least one joining surface to be at least partially melted or melted is brought into contact with the welding mirror by moving the welding mirror. However, it is most preferred that both joining surfaces be melted by the heating device, such as a welding mirror, as this allows a particularly stable weld to be formed. For this purpose, the welding mirror is moved between the plastic profiles to be joined. As soon as the welding mirror is located between the plastic profiles, the plastic profiles are pressed against the heating device by the pressing device. Once the joining surfaces have been sufficiently melted or melted, the plastic profiles are moved away from the welding mirror and the heating device is returned to its starting position.Once the welding mirror between the plastic profiles has been removed, the melted or melted, still warm connecting surfaces of the plastic profiles are first pressed together using the pressing device and then using the pressing device.

[0055] Depending on the embodiment of the method according to the invention, the heating device, such as the welding mirror, can be moved manually or automatically. The heating time, i.e., the time required to melt the at least one plastic profile, can be adjusted, for example, depending on the plastic from which the plastic profiles are made.

[0056] To press the two plastic profiles together, at least one of the two clamping devices is set in motion and moved toward the other clamping device. Initially, a pressure device acts on the clamping device to be moved. After a few milliseconds, the pressing device is activated, which exerts a greater force on the clamping device to be moved than the pressing device. This allows the clamping device to be moved precisely while still pressing the plastic profiles against each other with high force. According to the invention, the technical operating principles of the pressing device and the pressing device differ from one another.

[0057] Particularly with regard to welding previously mitered plastic profiles used to form window and door frames, it has proven advantageous if the first clamping device and the second clamping device are moved at right angles to each other, for example. For this purpose, the guides guiding the clamping devices are advantageously aligned at right angles to each other.

[0058] Preferably, one of the plastic profiles is clamped between a support surface and a clamping element of the respective clamping device, wherein the first and second clamping devices are L-shaped, a horizontal leg of the L-shaped clamping device forms a support surface, and at least one clamping element is provided on a vertical leg. To clamp the plastic profiles, the clamping elements can be moved along the vertical leg, whereby it can be determined, for example, by means of a displacement or force sensor whether the plastic profile is correctly clamped.

[0059] For welding mitered plastic profiles, it has also proven advantageous if the support surfaces and clamping elements have a triangular or convex-square shape in plan view, and the plastic profiles are clamped between the support surfaces and clamping elements in such a way that the connecting surfaces of the plastic profiles are almost flush with the support surfaces and / or clamping elements. This has the advantage that the plastic profiles cannot bend or even break when joined under high pressure.

[0060] To correctly position the plastic profiles within the clamping devices and thus create a high-quality welded joint, it has proven advantageous to position the plastic profiles in the clamping devices using a positioning aid. Depending on the embodiment of the method according to the invention, at least one positioning pin and / or at least one contact surface against which the plastic profiles are placed or clamped can be used as positioning aids.

[0061] The weld beads created when the plastic profiles are pressed together are removed by the cleaning mechanism, resulting in a smooth surface. Removal can be achieved using at least one blade, at least one knife, at least one pair of scissors, at least one pair of pliers, at least one saw, or similar.

[0062] Optimally, a weld bead that forms when the plastic profiles are pressed against one another is severed by moving a first blade provided on the clamping element of the first clamping device and a second blade provided on the clamping element of the second clamping device, as well as a third blade provided on the support surface of the first clamping device and a fourth blade provided on the support surface of the second clamping device, towards one another. In this process, a first weld seam is squeezed between the first and second blades, and a second weld seam is squeezed between a third and fourth blade and cut off. Depending on the embodiment of the method according to the invention, several blades or just one blade extending over the entire length of the weld seam can be used to cut off a weld seam.

[0063] It is particularly advantageous if the first and second blades, as well as the third and fourth blades, are moved toward each other to such an extent that a gap of 0 to 0.15 mm is formed between them, as this allows the entire or almost entire weld seam to be removed. It is essential for this that the clamping devices and guides are arranged in such a way that the blades can be moved together sufficiently and the clamping devices are pressed against the weld bead with sufficient force to separate it. Advantageously, such a high force can be easily achieved by providing the second movement mechanism.

[0064] It has proven particularly advantageous if the clamping device is operated pneumatically and the pressing device hydraulically and / or electromechanically and / or with a toggle lever. Especially when using pressures below 20 bar, a pneumatic cylinder can be very well controlled, allowing the plastic profiles to be brought into contact precisely and carefully. By using and staggering the activation of the hydraulically operated pressing device, the plastic profiles can then be pressed together with great force. Using an electromechanical drive for the pressing device enables particularly high-precision control of the force path. However, this may result in higher costs.

[0065] To avoid impacts when activating the pressure device, it has proven advantageous to couple the pressure device and the pressure mechanism so that they interact. If the pressure device has a pneumatic cylinder and the pressure device has a hydraulic cylinder, it is advantageous to connect the pneumatic and hydraulic cylinders in such a way that their pistons can only be moved together. Such a connection can be achieved, for example, by a mounting plate attached to the piston. Furthermore, the coupling can be implemented in such a way that the air moved by the pneumatic cylinder acts on the piston of the hydraulic cylinder.By coupling the pneumatic cylinder to the hydraulic cylinder, hydraulic fluid contained in the hydraulic cylinder is moved back and forth in a cylinder tube of the hydraulic cylinder during the pneumatic cylinder's activation, in accordance with the piston movement. Advantageously, such a design allows a very high force to be generated when the hydraulic cylinder is activated, even with comparatively little hydraulic fluid.

[0066] It has also proven suitable for hydraulic fluid to be drawn from and / or introduced into a hydraulic fluid reservoir of the hydraulic cylinder when a piston of a hydraulic cylinder moves due to a movement of a pneumatic cylinder. An additional hydraulic fluid reservoir provided on the piston rod side of the hydraulic cylinder, from which hydraulic fluid can be drawn or into which hydraulic fluid can be introduced, prevents ambient air from being drawn into the cylinder tube of the hydraulic cylinder during a piston movement of the hydraulic cylinder caused by the drive of the pneumatic cylinder. This advantageously allows the efficiency of the hydraulic cylinder to be kept consistently high.

[0067] For optimal joining of the plastic profiles, it has also proven advantageous if the first clamping device is moved by a first of the at least one pressing device and subsequently by a first of the at least one pressing device, and the second clamping device is moved by a second of the at least one pressing device and subsequently by a second of the at least one pressing device. This allows the contact force to be further increased. The flexibility and precision in positioning the plastic profiles can also be increased compared to the movement of only one clamping device.

[0068] It has also proven advantageous if the clamping devices are coupled and stabilized by a pressure device, such as a hydraulic cylinder. Particularly when at least one pressure device is operating, very high forces are exerted on the clamping devices, which can cause the clamping devices to be forced apart, particularly in an upper region. This can result in the resulting weld seam not having a constant width and the resulting weld beads not being completely separated. By acting with a hydraulic cylinder, preferably at the upper ends of the clamping devices, this can prevent the clamping devices from being forced apart, and a high-quality weld seam can be created.

[0069] With regard to the joining result, it has also proven advantageous if a force in the range of 1000 N to 3000 N is applied to at least one of the plastic profiles with the pressing device, and a force in the range of 19000 N to 22000 N with the clamping device. However, such forces are preferably applied to both joining partners.

[0070] In further embodiments of the method according to the invention, however, other forces can also be exerted on the plastic profiles by the pressing and / or clamping device. For example, the pressing device can also apply a force of only between 500 N and 1000 N. The clamping device can also be designed to exert a force below 19,000 N. Furthermore, forces exceeding 22,000 N can also be exerted with the clamping device.

[0071] Preferred embodiments of the present invention, their structure, function and advantages are explained in more detail below with reference to figures, wherein Fig. 1 shows plastic profiles to be connected in a view from the front above, Fig. 2 shows an embodiment of a device according to the invention in a front view, Fig. 3 which in Fig. 2 shown device in a side view, and Fig. 4 which in the Fig. 2 and Fig. 3 shows a plan view of the device shown.

[0072] Fig. Figure 1 shows plastic profiles 6, 6' to be connected in a front-top view. The plastic profiles 6, 6' are made of a plastic, such as polyvinyl chloride. Fig. In the embodiment shown in Figure 1, the ends 61, 61' of the plastic profiles 6, 6' to be connected are mitred, so that the plastic profiles 6, 6' form, for example, a corner of a window or door frame after connection.

[0073] The plastic profiles 6, 6` are used with a Fig. 2 shown device 1 at connecting surfaces 60, 60`, whereby for the sake of clarity the plastic profiles 6, 6` to be joined are shown in Fig. 2 are not shown.

[0074] The Fig. The device 1 shown in Figure 2 has two clamping devices 2, 2' for clamping and positioning the plastic profiles 6, 6' to be connected. The clamping devices 2, 2' are mounted so as to be movable on two guides 8, 8' arranged at right angles to one another. The essentially L-shaped clamping devices 2, 2' are each connected to a guide 8, 8' by means of a horizontal leg 22, 22' of the L. At the same time, the horizontal legs 22, 22' of the L form support surfaces 23, 23' for the plastic profiles 6, 6'. Clamping elements 24, 24' are provided on vertical legs 21, 21' of the L, which are vertically movable and serve to clamp the plastic profiles 6, 6'.

[0075] The clamping elements 24, 24' are mounted on vertically aligned guides 242, 242' for moving the plastic profiles along a travel path on a machine table 10. These guides are provided on the vertical legs 21, 21' of the L of the clamping devices 2, 2'. The clamping elements 24, 24' are each driven by a cylinder 243, 243', which is arranged at an upper end of the clamping device 2, 2'.

[0076] The L-shaped clamping devices 2, 2' are arranged on the horizontally aligned guides 8, 8' in such a way that the ends 221, 221' of the horizontal legs 22, 22' of the L, to which the vertical legs 21, 21' of the L are not attached, point towards each other. The ends 221, 221' of the horizontal legs 22, 22' are rectangular in plan view, so that they can be moved flush together despite the right-angled arrangement of the clamping devices 2, 2'. In the moved-together state of the clamping devices 2, 2', as shown in Fig. As shown in Figure 2, the clamping devices 2, 2' form a corner similar to that found in door or window frames. The plastic profiles 6, 6' to be connected to form such a corner can thus be positioned and connected particularly easily and precisely in the clamping devices 2, 2'.

[0077] As in Fig. 2, the ends 241, 241' of the clamping elements 24, 24' are also triangular in the illustrated embodiment, so that they also touch each other in the retracted state of the clamping devices 2, 2' and form a corner.

[0078] Such an arrangement and design of the clamping devices 2, 2' has proven particularly advantageous for connecting corners of window and door frames. In further embodiments of the device 1 according to the invention, the clamping devices 2, 2' can, however, also be arranged and designed differently. For example, the clamping devices 2, 2' can be arranged not at right angles to one another, but as a straight extension of one another or at any other desired angle to one another. Likewise, the clamping devices 2, 2' do not have to be L-shaped. Rather, the clamping devices 2, 2' can also be C-shaped or I-shaped. In further embodiments of the device 1 according to the invention, more or fewer clamping elements 24, 24' and / or support surfaces 23, 23' or differently designed clamping elements 24, 24' and / or support surfaces 23, 23' can be attached to a clamping device 2, 2'.

[0079] Due to the corner-forming design of the device 1 when the clamping devices 2, 2' are retracted, the plastic profiles 6, 6 to be connected can be placed particularly easily and accurately in the clamping devices 2, 2'. Advantageously, the clamping devices 2, 2' have contact surfaces 91, 91' for this purpose, against which the plastic profiles 6, 6' can be placed flush. Furthermore, the positioning aid 9 of the device 1 for arranging the plastic profiles 6, 6' has a contact surface 92. The contact surface 92 is arranged between the clamping devices 4, 4' and is vertically movable. Thus, the contact surface 92 can be moved out for placing and positioning the plastic profiles 6, 6' and can be retracted again after the plastic profiles 6, 6' have been positioned and clamped between the support surfaces 23, 23' and the clamping elements 24, 24'.Advantageously, the connection process of the plastic profiles 2, 2' is thus not disturbed by the contact surface 92.

[0080] In the Fig. In the embodiment of the device 1 according to the invention shown in Figure 2, a blade 71, 72, 73, 74 is provided at each of the ends 241, 241' of the clamping elements 24, 24' and the ends 221, 221' of the support surfaces 22, 22'. In the device 1 shown, the blades 71, 72, 73, 74 form a cleaning mechanism that serves to remove weld beads created when joining the plastic profiles 6, 6'. Advantageously, such an arrangement of the blades 71, 72, 73, 74 allows a weld bead to be removed directly during the pressing of the plastic profiles 6, 6' and thus during the formation of the respective weld bead, without a subsequent work step. In this case, welding beads that form above and below the plastic profiles 6, 6' are clamped and cut off between the blades 71 and 72 as well as 73 and 74 when the clamping devices 2, 2' are moved together.

[0081] In order to completely remove a weld bead created during joining and to provide a high-quality joining result with a very narrow weld seam, the present invention moves the clamping devices 2, 2' toward each other with sufficient force. For this purpose, the clamping devices 2, 2' are each coupled to a pressing device 3, 3' and a pressing device 4, 4'. The pressing and pressing devices 3, 3', 4, 4' are each arranged at the end of the guide 8, 8' at which the guides 8, 8' point away from each other.

[0082] The pressing and clamping devices 3, 3', 4, 4', each coupled to a clamping device 2, 2', differ from one another in their technical operating principle and purpose. Thus, the pressing device 3, 3', which in the illustrated embodiment is designed as a pneumatic cylinder, serves to slowly, precisely, and controllably move the clamping device 2, 2'. The pressing device 4, 4' is a hydraulic cylinder in the illustrated embodiment, which is activated at a time offset from the pressing device 3, 3' and serves to compress the plastic profiles 6, 6' and to move the clamping device 2, 2' and thus the plastic profiles 6, 6' under great force.The pressing device 4, 4' is advantageously activated at a time offset from the pressing device 3, 3', so that the plastic profiles 6, 6' can first be slowly positioned and brought into contact using the pressing device 3, 3' and then joined using the pressing device 4, 4' under high force. In particular, applying the high force at the end of the joining process ensures that any weld beads that may form can be completely severed and the weld seam is formed particularly narrow.

[0083] In the illustrated embodiment, the pneumatic cylinder is coupled to a piston of the hydraulic cylinder, so that when the air in the pneumatic cylinder is compressed and expanded, hydraulic fluid is forced into and out of the hydraulic cylinder. The pistons of the pneumatic and hydraulic cylinders can therefore only be moved together, meaning that hydraulic fluid is moved back and forth in the hydraulic cylinder even while the pneumatic cylinder is active. Thus, when the hydraulic cylinder is activated, comparatively little hydraulic fluid needs to be introduced into the hydraulic cylinder to generate high forces. In alternative embodiments of the device according to the invention, the pneumatic and hydraulic cylinders can also be mechanically coupled or operate independently of one another.

[0084] To melt the joining surfaces 60, 60', the device 1 has a heating device 5 with a welding mirror 51. The welding mirror 51 is movably mounted on the device 1 so that it can be placed between the plastic profiles 6, 6' to be joined. To position the welding mirror 51 between the plastic profiles 6, 6', the clamping devices 2, 2' are moved apart so that the welding mirror 51 can be arranged easily and collision-free between the plastic profiles 6, 6'. Once the welding mirror 51 is placed between the plastic profiles 6, 6', the clamping devices 2, 2' are moved together slowly and in a controlled manner by means of the pressing device 3, 3', and the plastic profiles 6, 6' are thus pressed against the welding mirror 51.

[0085] Insofar as the clamping devices 2, 2' are only moved with the pressing device 3, 3', they can be moved slowly and in a controlled manner and the plastic profiles 6, 6' can be brought into gentle contact with the welding mirror 51, thereby avoiding destruction of the welding mirror 51. Once the plastic profiles 6, 6' have been sufficiently melted or completely melted, the plastic profiles 6, 6' are moved apart again by means of the clamping devices 2, 2' so that the welding mirror 51 between the two plastic profiles 6, 6' can be removed. As soon as the welding mirror 51 has been moved back to its starting position, the at least partially melted or completely melted, still hot connecting surfaces 60, 60' of the plastic profiles 6, 6' are pressed together by means of the clamping devices 2, 2', thus forming a connection between them.

[0086] In order to produce a high-quality welded joint, the clamping devices 2, 2' are initially moved by means of the pressing device 3, 3' according to the invention. After a few milliseconds, the pressing device 4, 4' is activated. The pressing device 4, 4' can apply a greater force to the clamping devices 2, 2' than the pressing device 3, 3', whereby it can bring the plastic profiles 6, 6' closely together despite high opposing forces. Pressing the plastic profiles 6, 6' together causes deformations, particularly at the molten connecting surfaces 60, 60'. In the process, parts of the partially or molten plastic profiles 6, 6' are pushed outwards, resulting in the formation of an undesirable weld bead. Advantageously, this is severed directly when joining the plastic profiles 6, 6' due to the arrangement of the four blades 71, 72, 73, 74 on the clamping elements 24, 24' and the support surfaces 23, 23'.The high force that can be generated with the pressing device 4, 4' ensures that the clamping devices 2, 2' can be moved together to such an extent that welding beads that form above and / or below the plastic profiles 6, 6' can be completely severed.

[0087] In the Fig. In the embodiment shown in Figure 2, the device 1 has two clamping devices 2, 2' for connecting two plastic profiles 6, 6'. In alternative embodiments, however, the device 1 can also have more than two clamping devices 2, 2' for connecting more than two plastic profiles 6, 6'.

[0088] Fig. 3 shows the Fig. 2 shown device 1 in a side view, wherein the same reference numerals as in Fig. 2 identical components, which is why reference is made to the previous explanations on these. In Fig. 3, the L-shaped design of the clamping devices 2, 2' is particularly clearly visible. Furthermore, Fig. 3 that the device 1 is essentially surrounded by a housing 10.

[0089] Fig. 4 shows the Fig. 2 and Fig. 3, the device 1 shown in plan view, with the same reference numerals designating the same components. Unlike in the Fig. 2 and Fig. 3, the clamping devices 2, 2' are in Fig. 4 in a retracted position. Furthermore, Fig. 4 the welding mirror 51 is shown in an extended position, so that plastic profiles 6, 6' not shown here would be in contact with it and would be melted.

[0090] As in Fig.As shown in Figure 4, a movement mechanism 511 is provided at one end of the welding mirror 51 for moving it. Depending on the design, the movement mechanism 511 can be a hydraulic or pneumatic cylinder. Furthermore, an electromechanical drive or a toggle lever can also be used to move the welding mirror 51.

Claims

[1] Device (1) for connecting a first plastic profile (6) to a second plastic profile (6') at their connecting surfaces (60, 60'), wherein the device (1) a first clamping device (2) for holding and positioning the first plastic profile (6) and a second clamping device (2') for holding and positioning the second plastic profile (6'), wherein at least one of the clamping devices (2, 2') is movable so that the plastic profiles (6, 6') can be moved towards and away from each other; a heating device (5) positionable between the connecting surfaces (60, 60') for at least partially melting at least one of the connecting surfaces (60, 60'); at least one pressing device (3, 3') at least for pressing the connecting surfaces (60, 60') against the heating device (5) and for pressing the plastic profiles (6, 6') against each other; and a cleaning mechanism (7) for removing a welding bead created when the plastic profiles (6, 6') are connected; characterized by , that the device (1) has, in addition to the pressing device (3, 3'), at least one pressing device (4, 4') for pressing the plastic profiles (6, 6') against one another, wherein the technical operating principle of the pressing device (4, 4') differs from the technical operating principle of the pressing device (3, 3') and a higher force can be exerted on the plastic profiles (6, 6') by the pressing device (4, 4') than by the pressing device (3, 3'). [2] Device according to claim 1, characterized by that the pressing device (3, 3') has a pneumatic cylinder and the pressing device (4, 4') has a hydraulic cylinder, an electromechanical drive and / or a toggle lever. [3] Device according to claim 2, characterized bythat the pressing device (4, 4') has a hydraulic cylinder, wherein the pneumatic cylinder is coupled to a piston of the hydraulic cylinder. [4] Device according to claim 3, characterized by that a hydraulic fluid inlet and outlet is provided in a cylinder tube of the hydraulic cylinder on both sides of the piston, wherein at least the hydraulic fluid inlet and outlet provided on one piston rod side of the hydraulic cylinder is connected to a hydraulic fluid reservoir. [5] Device according to at least one of the preceding claims, characterized bythat both clamping devices (2, 2') are movable and the first clamping device (2) is connected to a first of the at least one pressing device (3, 3') and a first of the at least one pressing device (4, 4') and the second clamping device (2') is connected to a second of the at least one pressing device (3, 3') and a second of the at least one pressing device (4, 4'). [6] Device according to at least one of the preceding claims, characterized by that the at least one pressing device (3, 3') and the at least one pressing device (4, 4') are provided on guides for the clamping devices (2, 2'). [7] Device according to at least one of the preceding claims, characterized by that the first and second clamping devices (2, 2') are coupled on their upper side opposite a machine bed (10) by means of the pressing device (4, 4'). [8] Device according to claim 7, characterized bythat the machine table (10) is made of a metal plate at least 10 cm thick. [9] Method for connecting a first plastic profile (6) to a second plastic profile (6') at their connecting surfaces (60, 60'), wherein the first plastic profile (6) is held in a first clamping device (2) and the second plastic profile (6') is held in a second clamping device (2'); the connecting surfaces (60, 60') of the plastic profiles (6, 6') are pressed with at least one pressing device (3) along a travel path relative to one another and against a heating device (5) positioned between the connecting surfaces (60, 60'); at least one of the connecting surfaces (60, 60') is at least partially melted by the heating device (5); then the heating device (5) is moved away from the plastic profiles (6, 6'); and then the connecting surfaces (60, 60') are pressed against each other using the pressing device (3, 3') and thereby connected; and a welding bead created when the plastic profiles (6, 6') are joined is removed; characterized by , that for connecting the connecting surfaces (60, 60') of the plastic profiles (6, 6') in an end section of the travel path, in addition to the pressing device (3, 3'), at least one pressing device (4, 4') is used, which presses the connecting surfaces (60, 60') of the plastic profiles (6, 6') against one another with a different technical operating principle than that of the pressing device (3, 3') and with a higher force than the pressing device (3). [10] Method according to claim 9, characterized bythat the pressing device (3, 3') operates pneumatically and the pressing device (4, 4') operates hydraulically, electrically and / or with a toggle lever. [11] Method according to claim 9 or 10, characterized by that when a pneumatic cylinder of the pressing device (3, 3') moves, a piston of a hydraulic cylinder of the pressing device (4, 4') is also moved. [12] Method according to at least one of claims 9 to 11, characterized by that the first clamping device (2) is moved by a first of the at least one pressing device (3, 3') and subsequently by a first of the at least one pressing device (4, 4') and the second clamping device (2') is moved by a second of the at least one pressing device (3, 3') and subsequently by a second of the at least one pressing device (4, 4'). [13] Method according to at least one of claims 9 to 12, characterized bythat with the pressing device (3, 3') a force which lies in a range of 1000 N to 3000 N is exerted on at least one of the plastic profiles (6, 6') and with the pressing device (4, 4') a force which lies in a range of 19000 N to 22000 N.

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