Spin-welding device for producing a welded joint

Abstract

The invention relates to a spin-welding device (1) for producing a spot-like or linear welded joint (31) between a plastic panel (3) and a metal or plastic substrate (4), comprising a welding head (2) and a manually actuatable or controlled linear feed for linear movement of the welding head (2), wherein: the welding head (2) comprises a rotatable or oscillatable spinning pin (7) and an outer sleeve (9) that surrounds the spinning pin (7); a reservoir (11) for receiving a material displaced by the spinning pin (7) is provided between the outer sleeve (9) and the spinning pin (7); the reservoir (11) is delimited by a step formed integrally on the outer sleeve (9) or by a reservoir sleeve (12) provided between the outer sleeve (9) and the spinning pin (7).

Description

[0001] Stir welding device for producing a welded joint

[0002] The invention relates to a stir welding device for producing a point-shaped or linear welded connection between a plastic plate or a plastic molded part and a metal or plastic substrate, comprising a welding head with a rotatable or oscillatable stirrer pin and an outer sleeve surrounding the stirrer pin.

[0003] According to the state of the art, plastic joints (hereby meaning the connection of two plastic components) and plastic-metal joints (hereby meaning the connection of a plastic component to a metal component) are primarily joined by gluing, conventional welding, screwing, or riveting. It is also possible to directly apply plastics using injection molding, but this is complex and only of limited use, as the liquid plastic would fill all the hollow spaces, such as those required in a housing. Therefore, a housing cover cannot simply be injection molded on.

[0004] Screw and riveted joints require additional seals, which can become porous over time or cause leaks due to settling or swelling. This can allow water or dirt to enter or exit.

[0005] Also known from the prior art are so-called friction stir welding (FSW) processes, in which a rotating stirrer pin penetrates two materials to be joined and remains rotating in the material to generate heat. These processes can be performed as spot welding processes or as linear welding processes, with the machines developed for this purpose preferably being designed for the respective welding process and generally not used interchangeably for both types of welding processes due to the respective requirements.

[0006] Since the welding process in friction stir welding of plastics is controlled exclusively by the penetration and rotation of the tool, a porous area often forms in or around the weld nugget. Large bubbles also frequently form, caused by thermal shrinkage during the cooling phase.

[0007] CN 109967858 A discloses a stir welding device for producing a linear weld seam. A stirrer pin is guided within a simple outer sleeve that rests on the plastic material to be welded. The outer sleeve is surrounded by a heating device. CN 113020776 also shows a stir welding device for producing a linear weld seam, with a stirrer pin provided as a single piece on the tool head.

[0008] DE102014112683A1 discloses a hybrid joining technique in which friction and ultrasonic energy are applied to the workpiece simultaneously. A central horn directs ultrasonic waves into the workpiece. The horn is surrounded by an annular friction tool that is frictionally connected to the tool.

[0009] WO 2022 / 045171 A1 discloses a stir welding device for spot welding. In this document, the stirrer pin is surrounded by an inner and an outer sleeve. Heat generation for the welding process in this device occurs exclusively through friction. The tool is used exclusively for spot welding, and its use for linear welding is not feasible because the inner sleeve can also penetrate the material to be welded, which would prevent linear movement. Similar spot welding processes are disclosed in WO2022045171A1, EP3909714A1, and WO2015145251A1.

[0010] KR20070061937A also shows a stir welding device for spot welding. This device is designed to weld two metal layers together. Since the upper layer must also be made of metal, longitudinal movement of the device is not possible.

[0011] It is the object of the invention to overcome these problems of the prior art and to provide a stir welding device for producing a linear or spot weld of a plastic plate on a metal or plastic substrate.

[0012] This object is achieved by a stir welding device for producing a point-shaped or linear welded connection between a plastic plate or a plastic molded part (hereinafter referred to only as the plastic plate, whereby welding of a plastic molded part is also encompassed by the invention) and a metal or plastic substrate, comprising a welding head with a rotatable or oscillatable stirrer pin and an outer sleeve surrounding the stirrer pin, wherein a reservoir for receiving a material displaced by the stirrer pin is provided between the outer sleeve and the stirrer pin, wherein the reservoir is preferably delimited by a shoulder formed integrally on the outer sleeve or by a reservoir sleeve provided between the outer sleeve and the stirrer pin (alternatively, the stirrer pin could also have a shoulder or the like),wherein the stir welding device further comprises a heating device for directly heating the stirring pin.,

[0013] The reservoir according to the invention makes it possible for the first time to ensure that an extremely tight weld joint can be produced even with a linear welding process. The reservoir prevents the material displaced by the stirring pin (which originates from the plastic plate or the metal or plastic substrate) from swelling outwards, as the pressure present in the reservoir ensures that the material does not freely swell outwards, thereby preventing air pockets. According to the invention, the pressure during the production of the weld joint can thus be regulated by the outer sleeve or the reservoir sleeve, whereby the shrinkage effect can be further compensated, whereas in the prior art the welding pressure is generated exclusively via the contact force of the tool on the base.

[0014] In summary, this allows for significantly tighter welded joints than was possible with the prior art. In particular, no additional seals are required, which could become porous over time or cause leaks due to settling or swelling.

[0015] If a multi-part sleeve system with a reservoir sleeve is used, this can be used to collect excess material, as it can be designed to be movable relative to the outer sleeve. However, the reservoir sleeve cannot be moved beneath the outer sleeve, meaning it cannot penetrate the plastic plate, as this would prevent a linear weld connection. An outer sleeve with a shoulder, on the other hand, is easier to manufacture and control. In particular, with this system with a one-piece outer sleeve with a shoulder, it is easier to provide a through-hole or bridge for a power connection for heating the stirring pin.

[0016] According to the invention, the stir welding device further comprises a heating device for directly heating the stirrer pin. In contrast to the prior art, the process heat therefore does not have to be generated via the friction between the tool and the workpiece, since this is provided by the already heated stirrer pin. According to the invention, the frictional heat serves merely to condition, i.e. to preheat, the workpiece. The temperature to which the stirrer pin is heated can be selected depending on the materials of the workpiece, the feed rate of the welding head, etc., and can be regulated via a control unit if necessary. With regard to CN 109967858 A, it should be mentioned that this teaches the heating of a shoulder which is arranged around the welding head, whereby the workpiece is only preconditioned, but the stirrer pin is not directly heated, so that the process heat must again be generated by the friction of the stirrer pin.In contrast, in the present invention, the outer sleeve could even be cooled while the stirring pin is directly heated.

[0017] The directly heated stirrer pin thus has the advantage that the required process heat does not have to be generated exclusively through friction. The invention opens up new areas of application, as the process heat for plastic welding, for example, can hardly be achieved through friction. The friction coefficient of plastic is very low and the insulating effect of the plastic prevents heat from "spreading forward." Furthermore, the directly heated stirrer pin allows for lower rotation speeds, which counteracts the shearing effect within the weld metal and allows the material to move more effectively around the pin.

[0018] Furthermore, it should be emphasized that the reservoir and the directly heated stirring pin have a synergistic effect, since the material in the reservoir can be kept at working temperature.

[0019] To implement the direct heating of the rotating or oscillating stirring pin, the heating device can comprise a heating cartridge arranged in the stirring pin, which is preferably connected to a power source arranged outside the stirring pin via sliding contacts. Alternatively, the heating device could comprise an induction coil arranged around the stirring pin and an inductively heatable material in or on the stirring pin. These two embodiments are particularly preferred for heating the stirring pin itself during rotation or oscillation. In further variants, a heat transfer medium could be passed through the stirring pin, although this is extremely complex.

[0020] Particularly preferably, the stir welding device further comprises a manually operable or controlled linear feed for the linear movement of the welding head during the welding process. In practice, it has been found that the stir welding device according to the invention, due to the tight welded joints, is particularly suitable for producing tight linear welded joints, for example, in order to tightly mount a cover on a housing. Furthermore, the welding head, preferably the outer sleeve, preferably comprises a through-opening leading to the reservoir for external material supply. The through-opening can be used, in particular, to further regulate the welding pressure by supplying welding consumables.

[0021] In a further preferred embodiment, the stir welding device comprises a coupling which selectively couples the stirrer pin to the outer sleeve and / or the reservoir sleeve for transmitting torque. Although it is usually preferred for the outer sleeve to rest on the plastic plate without rotation, rotation of the outer sleeve or the reservoir sleeve can be provided in order to promote mixing of the material in the reservoir or, when using a profiled outer sleeve, to follow a predefined contour. According to the invention, the outer sleeve can be secured against rotation by means of the coupling - a so-called stop-lock function. Depending on the design, the stirrer pin can also be coupled to one or both of the aforementioned sleeves so that they rotate along with the stirrer pin.

[0022] It is further preferred if the stirring pin has a section facing the plastic plate, at least a portion of which is designed as a conveyor screw. The rotation thus allows material to be conveyed from the reservoir into the joining zone. In this embodiment, the outer sleeve preferably has a tapered section facing the plastic plate, so that the reservoir is not directly adjacent to the plastic plate. However, this is not mandatory in other embodiments; the section with a conveyor screw can also be combined with all other embodiments.

[0023] In a further aspect, the invention relates to a stir welding method with a stir welding device according to one of the aforementioned embodiments, comprising the steps:

[0024] Placing the plastic plate on the metal or plastic substrate,

[0025] - Inserting the stirring pin into the plastic plate until it penetrates the plastic plate and at least contacts the metal or plastic substrate, and placing the outer sleeve on the plastic plate (this can also be done before inserting the stirring pin),

[0026] - Moving the welding head by means of the linear drive with a rotating or oscillating stirring pin while the stirring pin penetrates the plastic sheet and at least contacts the metal or plastic substrate, to create a linear weld. Furthermore, the stirring pin is preferably heated directly during this movement.

[0027] The stir welding method according to the invention has the same advantages as those explained above for the stir welding device. In particular, the welding pressure can be further regulated if welding consumables are introduced into the reservoir via the through-hole during the movement of the welding head to create a linear weld or to close the end hole.

[0028] The welding process is particularly advantageous when the metal or plastic substrate is a housing with an opening and the plastic plate is a cover, wherein the welding process comprises the following steps:

[0029] Place the lid on the opening, and

[0030] Creating a closed linear weld (e.g. an annular or diamond-shaped weld) around the opening to tightly seal the opening with the cover, ie the opening lies within the annular weld.

[0031] With this welding process, the opening can be sealed particularly tightly without the need for any further measures.

[0032] This stir welding process is particularly advantageous when the plastic plate and / or the plastic substrate is made of polyamide, preferably PA6 GF30, and the metal substrate, if present, is made of aluminum, preferably cast aluminum, particularly preferably cast aluminum EN AC44200. It is understood, however, that the stir welding process according to the invention is not limited to these materials, but could also be used for other materials, such as aluminum EN AW6082 for the metal substrate or polycarbonate for the plastic plate or the plastic substrate.

[0033] These and further advantageous embodiments of the method according to the invention are explained in more detail below with reference to the figures.

[0034] Figure 1 shows a stir welding device according to the invention in a schematic side view.

[0035] Figure 2 shows a welded connection created between a cover and a housing using the stir welding device of Figure 1. Figure 3 shows a variant of the stir welding device according to the invention with a multi-part sleeve system.

[0036] Figure 4 shows a further variant of the stir welding device of Figure 1 with a stirring pin whose tip is designed as a conveyor screw.

[0037] Figure 5 shows a first embodiment of a heating device for the stir welding device according to the invention.

[0038] Figure 6 shows a second embodiment of a heating device for the stir welding device according to the invention.

[0039] Figures 7a - 7c show temporally successive states when using the stir welding device according to the invention.

[0040] Figures 8a and 8b show a further variant of the stir welding device according to the invention with a profiled outer sleeve in a front view and a side view.

[0041] Figures 9a and 9b show a further variant of the stir welding device according to the invention with an asymmetrical profiled outer sleeve in a front view and a side view.

[0042] Figure 1 shows a stir welding device 1 with a welding head 2. The stir welding device 1 is intended to be used to produce a linear weld 31 (Figure 2), e.g. an elongated weld seam, between a plastic plate 3 and a metal or plastic substrate 4. However, the plastic plate 3 does not have to be completely flat, so that it can generally also be referred to as a plastic molded part. The metal or plastic substrate 4 can, for example, be another plate or a solid body. The weld 31 produced with the stir welding device 1 should be particularly tight after production so that the weld 31 between the plastic plate 3 and the metal or plastic substrate 4 can be used, for example, in automobile construction, in aeronautical technology or in so-called "white goods".

[0043] In particular, the plastic plate 3 can be a lid and the metal or plastic substrate 4 can be a housing, as shown in Figure 2. The housing can have an opening 30, and the lid is arranged covering the opening 30. The stir welding device 1 is used to produce a tight weld 31 around the opening 30, whereby the opening 30 is tightly closed. In Figure 2, the weld 31 is shown as annular, but it could also be diamond-shaped or the like. Furthermore, the present invention is not limited to this application, and in general only linear, i.e. not circumferential, welds 31 could be produced. Furthermore, the workpiece does not have to be a combination of housing and lid.

[0044] To achieve a linear feed of the welding head 2, a holding device (not shown in detail) for the welding head 2 can be inserted into a tool holder 5 of the stir welding device 1, which is shown in Figure 1. The tool holder 5 can be moved, for example, on a rail system 6 of the stir welding device 1, so that the welding head 2 can be moved in a plane spanned by the x-direction and the y-direction shown. This plane is usually parallel to the plastic plate 3 or the metal or plastic substrate 4. In addition to this linear feed, the stir welding device 1 can further comprise means for lowering and raising the welding head 2 or parts of the welding head 2 in the z-direction, i.e., in the direction of the plastic plate 3 or the metal or plastic substrate 4.

[0045] It is understood, however, that the illustrated embodiment of the linear feed is only an example and could generally be implemented differently, e.g., even rotary. The linear feed could also be manually operated, e.g., by one or more handwheels, or controlled automatically, so that the stir welding device 1 could be implemented as a CNC (computerized numerical control) machine.

[0046] In other embodiments, however, the stir welding device 1 could also be used for spot welding, so a linear feed is not absolutely necessary. For example, the workpiece could be moved to create another weld spot at a different location on the workpiece. In other embodiments, the linear drive can be used for spot welding, so that the welding head 2 is moved automatically or manually by means of the linear drive to a second location where another weld spot is to be created. The welding head 2 or the stirrer pin is raised before being moved to the next weld spot to avoid creating a linear weld seam.

[0047] To produce the welded joint 31, the welding head 2 comprises a rotatable or oscillating stirring pin 7, which can be lowered toward the plastic plate 3 and the metal or plastic substrate 4, here in the z-direction. This can be achieved, for example, by lowering the tool holder 5, whereby the stirring pin 7 does not have to perform any relative movement with respect to the tool holder 5, as shown in Figure 1, or by a relative movement of the stirring pin 7, which can be brought about by the spring 8 shown as an example in Figure 3. The stirring pin 7 can be made of metal or ceramic and, if necessary, have a coating, in particular a Teflon coating. Furthermore, the stirring pin 7 can have a profiling or notching on its outer contour.

[0048] In order to ensure that the material of the plastic plate 3 or the metal or plastic substrate 4 displaced by the stirring pin forms a welded joint 31 that is particularly tight towards the outside, the welding head 2 further comprises an outer sleeve 9 surrounding the stirring pin 7. The outer sleeve 9 has a preferably flat support surface 10 which faces the plastic plate 3 so that the outer sleeve 9 can move on the plastic plate 3 during a linear feed with the stirring pin 7 inserted. This allows the outer sleeve 9 to seal the area around the stirring pin 7. The outer sleeve 9 can be made of metal or ceramic and can optionally have a coating. It can be designed to be either rotationally symmetrical or profiled, for example to create a fillet weld. See also Figures 8a to 9b below.

[0049] To collect the material displaced during the penetration of the stirring pin 7 into the plastic plate 3 or into the metal or plastic substrate 4, a reservoir 11 is provided at the lower end between the outer sleeve 9 and the stirring pin 7. The "lower end" herein refers to the end facing away from the tool holder 5 or the end facing the plastic plate 3.

[0050] The reservoir 11 can be designed in various ways according to the invention. As shown in Figure 1, the outer sleeve 9 could have a widening shoulder at its lower end, which is limited at the top to form the reservoir 11. The shoulder has an appropriate height to collect a predetermined amount of leaked material. The shoulder could also be tapered, as shown in Figure 4, so that the reservoir 11 is located above the shoulder. In this case, the reservoir 11 could be enclosed by an upwardly widening stirring pin 7 between the outer sleeve 9 and the stirring pin 7.

[0051] As shown in Figure 3, however, a reservoir sleeve 12 provided between the outer sleeve 9 and the stirring pin 7 can also be used, which forms a reservoir 11 at the lower end of the welding head 2 in that the reservoir sleeve 12 limits the space occurring between the outer sleeve 9 and the stirring pin 7 at the top. In this embodiment, it can be provided in particular that a relative movement of the reservoir sleeve 12 and the outer sleeve 9 and preferably also of the stirring pin is enabled in order to adjust the height of the reservoir 11, i.e. to adjust the distance between the support surface 10 of the outer sleeve 9 and the lower end of the reservoir sleeve 12, which can be implemented by the spring 13 shown as an example in Figure 3. The reservoir sleeve 12 can also be made of metal or ceramic and can optionally have a coating.

[0052] Furthermore, a relative movement between the outer sleeve 9 and the stirring pin 7 in the z-direction can be made possible, for example by the spring 14 shown schematically in Figures 1 and 3. In the embodiment of Figure 1, for example, it could be provided that no relative movement in the z-direction between the stirring pin 7 and the tool holder 5 is possible, wherein the spring 14 still allows a relative movement in the z-direction between the stirring pin 7 and the outer sleeve 9.

[0053] Figure 3 shows that the welding head 2 could provide its own spring 8, 13, 14 for the stirring pin 7, the outer sleeve 9, and the reservoir sleeve 12, in order to enable a relative movement in the z-direction of all of these elements to one another and to the tool holder 5. The relative movement can be actuated, for example, electromagnetically, hydraulically, or purely mechanically, whereby the springs 8, 13, 14 can be used to achieve a restoring force, or they can be omitted, e.g., if the selected drive does not require a restoring force. It is understood that it is not absolutely necessary to provide a relative movement in the z-direction of all of these elements to one another and to the tool holder 5, so that lowering the tool holder 5 leads to an identical movement of the respective element for which no relative movement in the z-direction with respect to the tool holder 5 is provided.

[0054] As already explained, the stirring pin 7 is rotatable and / or oscillatable for producing the welded joint 31, in each case about an axis A running in the z-direction. The rotational movement or the oscillation movement is usually adjustable by the stir welding device 1 or by a user. The rotational or oscillation speed can be selected, for example, depending on the materials of the plastic plate 3 and the metal or plastic substrate 4; however, this is not absolutely necessary, since in many embodiments of the method according to the invention, the main heat is not to be achieved by the rotational movement or the oscillation movement, but by a heating device for the stirring pin 7, as explained in more detail below.The outer sleeve 9 and the reservoir sleeve 12 typically do not perform any rotational or oscillatory movement about the axis A running in the z-direction. However, this could be provided, whereby the rotational movement or the oscillatory movement of the stirring pin 7 can be selectively transmitted to the outer sleeve 9 and / or the reservoir sleeve 12 by means of a coupling. This can be advantageous for inducing a mixing movement in the reservoir 11.

[0055] Returning to Figure 1, it can be seen that the outer sleeve 9 has a through-opening 15 leading to the reservoir for external material supply. In particular, welding fillers can be introduced into the reservoir 11 to impart particularly preferred properties to the resulting weld joint 31. For example, an extruder (not shown) can be connected to the end of the through-opening facing away from the reservoir 11, or plastic wire can be fed in to transfer the welding fillers into the reservoir 11. This allows the welding pressure to be additionally regulated.

[0056] The through-opening 15 shown in Figure 1 for the integrally formed outer sleeve 9 can also be used in the embodiment of Figure 3, wherein the through-opening 15 here also preferably runs exclusively through the outer sleeve 9. However, the through-opening 15 could also run at least partially through the reservoir sleeve 12.

[0057] Figure 4 shows a particularly preferred further development which can preferably be used in combination with the through-opening 15. What is special here is that the stirring pin 7 comprises an upper section with a first diameter d1 and a lower second section with a second diameter d2 which is smaller than the first diameter d2. A conveyor screw F is formed at least partially on the second section, i.e. at least one groove-shaped notch with a gradient running in the z-direction. This allows material to be introduced particularly efficiently into the penetration point formed by the stirring pin 7 in the plastic plate 3 or in the metal or plastic substrate 4. As shown, however, the second section at the lower end is preferably not designed as a conveyor screw F, but rather comprises a substantially cylindrical or frusto-conical shape in order to penetrate better into the plastic plate 3 orto be able to penetrate into the metal or plastic substrate 4. In the embodiment shown in Figure 4, the reservoir 11 is preferably formed in that the outer sleeve 9 has a tapered shoulder 16 located at the lower end, which has an inner diameter of substantially d2 and engages around the second section of the stirring pin 7. Above the shoulder 16, the outer sleeve 9 has an inner diameter of substantially d1. In this embodiment, the reservoir 11 is therefore not located directly on the surface of the plastic plate 3, but at a distance above it. In a further embodiment not shown, the stirring pin could also have a shoulder and the outer sleeve could have a cylindrically shaped inner wall.

[0058] Furthermore, Figure 1 shows that the stirring pin 7 can comprise a heating device 17 for directly heating the stirring pin 7 and bringing it to a predetermined welding temperature. According to the invention, heat can therefore be introduced into the workpiece directly via the stirring pin 7. The embodiment of Figure 1 schematically shows that the stirring pin 7 can have two openings running parallel to the z-axis, in which heating cartridges can be arranged to convert electricity into heat.

[0059] A specific embodiment of the heating device 17 is shown in Figure 5, in which two sliding contacts 18 are provided, which are guided through the outer sleeve 9 and each contact an annular contact point 19 on the stirring pin 7. In other variants, the sliding contacts could also be guided via the outer sleeve 9 to the contact points 19, i.e., the outer sleeve 9 does not necessarily have to be perforated. The contact points 19 are in turn connected to one or more heating cartridges 20, which heat the stirring pin 7. With this embodiment, current can be transmitted into the interior of the stirring pin 7, even when it rotates or oscillates.

[0060] Figure 6 shows an embodiment in which an induction coil 21 is arranged around the stirring pin 7. When alternating current is applied to the induction coil 21 via lines 22, an alternating magnetic field is formed, by means of which the stirring pin 7 can be heated if it comprises inductively heatable material (i.e., electrically conductive material). In the illustrated embodiment, the stirring pin 7 comprises a heat conductor 23 within it. Since the induction coil 21 is not arranged directly within the stirring pin 7 in this embodiment, it is generally stated that the welding head 2 comprises a heating device 17 for directly heating the stirring pin 7 in order to bring it to a predetermined welding temperature. Furthermore, the stirring pin 7 could have a friction attachment 25 at the lower end facing the plastic plate 3 (see Figure 5).This is particularly advantageous when the welding process is carried out on a metal substrate 4, since the stirring pin 7 can thereby be additionally reinforced at the particularly stressed point.

[0061] With reference to Figures 7a, 7b, and 7c, the welding process performed with the welding head 2 explained above is described below. According to Figure 7a, the workpiece is first prepared, i.e., the plastic plate 3 is placed on the metal or plastic substrate 4. The welding head 2 is then arranged over the plastic plate 3 and displaced toward the plastic plate 3 until the stirring pin 7 and / or the support surface 10 of the outer sleeve 9 comes to rest on the plastic plate 3. At this point, the stirring pin 7 is preferably already heated by the heating device 17.

[0062] According to Figure 7b, the stirring pin 7 now penetrates into the plastic plate 3 and passes through it until the stirring pin 7 contacts the metal or plastic substrate 4, or penetrates the metal or plastic substrate 4 to a predetermined depth. When the stirring pin 7 is moved from the state in Figure 7a to the state in Figure 7b, the stirring pin 7 preferably rotates or oscillates about the axis A and / or is heated by the heating device 17. In any case, the stirring pin 7 rotates or oscillates when it comes into contact with the metal or plastic substrate 4 in order to condition it for the welding process.

[0063] It can be seen that by the penetration of the stirring pin 7 into the state in 7b material of the plastic plate 3 and possibly also material of the metal or plastic substrate

[0064] 4. This is held by the reservoir 11. However, since the reservoir 11 continues to hold the material under pressure, a predetermined or adjustable welding pressure is maintained. If the welding head 2 includes a reservoir sleeve 12, the amount of material held in the reservoir 11 can be adjusted by moving the reservoir sleeve 12 in the z-direction. In addition, the welding pressure can be further adjusted by conveying material into the reservoir 12 via the through-opening 15.

[0065] As shown in Figure 7c, the welding head 2 with rotating or oscillating and optionally heated stirring pin 7 can now be moved in the welding direction by means of the linear drive

[0066] 5 to produce a linear weld 31 between the plastic plate 3 and the metal or plastic substrate 4. It can be seen that behind the stirring pin 7, viewed in the welding direction S, a weld structure 24, i.e., an elongated weld seam, is formed, via which the plastic plate 3 is connected to the metal or plastic substrate 4. After the stirring pin 7 is removed from the plastic plate 3, the weld structure forms the weld 31.

[0067] Figures 8a and 8b show a variant of the outer sleeve 9 that is wedge-shaped. The tip of the wedge faces the workpiece and can be rounded if necessary. This outer sleeve is an example of a symmetrically profiled outer sleeve 9, in contrast to the rotationally symmetrical outer sleeve 9 of Figures 1 and 3. In other words, the support surface 10 of the outer sleeve 9 of Figures 8a, 8b has two flat partial regions 26 that are arranged symmetrically and at an angle around the axis A. For a welding process, the two partial regions 26 are arranged such that the welding direction S is parallel to the partial regions 26. Furthermore, an imaginary intersection line between the two partial regions 26 runs normal to the axis A and is parallel to the welding direction during a welding process. Such an outer sleeve 9 makes it possible, in particular, to produce fillet welds during a welding process.

[0068] Figures 9a and 9b show a modification of the outer sleeve 9, which is formed by two wedge-shaped pieces offset in the z-direction, the tips of which each face the workpiece and may be rounded. This outer sleeve 9 is an example of an asymmetrically profiled outer sleeve. In other words, the support surface 10 of this outer sleeve 9 has two first partial areas 27 and two second partial areas 28, which are each flat surfaces. At the lower end, which faces the workpiece, the two first partial areas 27 are arranged symmetrically and at an angle around the axis A, and the second partial areas 28 are also arranged symmetrically and at an angle (usually at the same angle as the first partial areas 27) around the axis A. Although both the first partial areas 27 and the second partial areas 28 are symmetrical to one another, the imaginary intersection line of the first partial areas 26 andThe second partial regions 27 are spaced apart in the z-direction, forming the two offset wedge-shaped pieces. Such an outer sleeve 9 allows, in particular, the creation of fillets or other seam shapes during a welding process.

[0069] Although the embodiments of Figures 8a-9b are shown in combination with the conveyor screw F and the internal reservoir 11, a wedge-shaped or otherwise designed outer sleeve 9 could also be used in combination with a reservoir 11 as shown in the embodiments of Figures 1 and 3.

Claims

Claims:

1. Stir welding device (1) for producing a point-shaped or linear weld connection (31) between a plastic plate (3) or a plastic molded part and a metal or plastic substrate (4), comprising a welding head (2) with a rotatable or oscillatable stirring pin (7) and an outer sleeve (9) surrounding the stirring pin (7), wherein a reservoir (11) for receiving a material displaced by the stirring pin (7) is provided between the outer sleeve (9) and the stirring pin (7), wherein the reservoir (11) is preferably delimited by a shoulder formed integrally on the outer sleeve (9) or by a reservoir sleeve (12) provided between the outer sleeve (9) and the stirring pin (7), characterized in that the stir welding device (1) further comprises a heating device (17) for directly heating the stirring pin (7).

2. Stir welding device (1) according to claim 1, wherein the heating device (17) comprises a heating cartridge arranged in the stirring pin (7), which is preferably contacted by means of sliding contacts (19) to an energy source arranged outside the stirring pin (7).

3. Stir welding device (1) according to claim 1, wherein the heating device (17) comprises an induction coil (21) arranged around the stirring pin (7) and an inductively heatable material in or on the stirring pin (7).

4. Stir welding device (1) according to one of claims 1 to 3, wherein the stir welding device (1) comprises a manually operable or controlled linear feed for the linear movement of the welding head (2) during the welding process.

5. Stir welding device (1) according to one of claims 1 to 3, wherein the welding head (2), preferably the outer sleeve (9), has a through opening (15) leading to the reservoir (11) for external material supply or material removal.

6. Stir welding device (1) according to one of claims 1 to 5, further comprising a coupling which selectively couples the stirrer pin (7) to the outer sleeve (9) and / or the reservoir sleeve (12) for transmitting a torque.

7. Stir welding device (1) according to one of claims 1 to 6, wherein the stirring pin (7) has a section facing the plastic plate (3) or the plastic molded part, at least a part of which is designed as a conveyor screw (F).

8. Stir welding method with a stir welding device (1) according to one of claims 1 to 7, comprising the steps: Placing the plastic plate (3) or the plastic molded part on the metal or plastic substrate (4), - Inserting the stirring pin (7) into the plastic plate (3) or into the plastic molded part until it penetrates the plastic plate (3) and at least contacts the metal or plastic substrate (4), and placing the outer sleeve (9) onto the plastic plate (3) or onto the plastic molded part, - Moving the welding head (2) by means of the linear drive with rotating or oscillating stirring pin (7) while the latter penetrates the plastic plate (3) or the plastic molded part and at least contacts the metal or plastic substrate (4) to produce a linear welded joint (31).

9. Stir welding method according to claim 8, wherein the metal or plastic substrate (4) is a housing with an opening (30) and the plastic plate (3) or the plastic molded part is a lid, comprising the steps: Place the lid on the opening (30), and - Creating a closed linear weld (31) around the opening (30) in order to tightly seal the opening (30) with the cover.

10. Stir welding method according to claim 8 or 9, wherein the plastic plate and / or the plastic substrate consists of polyamide, preferably PA6 GF30, and the optionally present metal substrate consists of aluminum, preferably cast aluminum, particularly preferably cast aluminum EN AC44200.

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