Friction stir welding device for producing welded joint

Abstract

The invention relates to a friction stir welding device (1) for producing a punctiform or linear welding joint (31) between a plastic sheet (3) and a metal or plastic substrate (4), comprising a welding head (2) and a manually operated or controlled linear feed device for linearly moving the welding head (2), wherein: the welding head (2) comprises a rotatable or oscillatory stirring pin (7) and a jacket (9) surrounding the stirring pin (7); a reservoir (11) for receiving the material displaced by the stirring pin (7) is arranged between the jacket (9) and the stirring pin (7); the reservoir (11) is defined by a step integrally formed on the jacket (9) or by a reservoir sleeve (12) disposed between the jacket (9) and the stirring pin (7).

Description

Technical Field

[0001] The invention relates to a friction stir welding device for producing a spot or linear weld joint between a plastic plate or a plastic molded part and a metal or plastic substrate, comprising a welding head with a rotatable or oscillating stirring pin and a jacket surrounding the stirring pin. Background Art

[0002] According to the prior art, plastic connections (understood here as the connection of two plastic parts) and plastic-metal connections (understood here as the connection between a plastic part and a metal part) are mainly obtained by means of adhesive bonding, conventional welding, screwing or riveting. In addition, there is the option of injecting the plastic directly by injection molding; however, this is a complex process and is only suitable in conditional cases, since the liquid plastic would fill all cavities, such as those required in the housing. Therefore, the housing cover cannot be simply injected. In the case of screwed and riveted connections, additional seals are required, which can become porous over time or leak due to settling or swelling. In this way, for example, water or dirt can enter or leave.

[0003] Furthermore, so-called friction stir welding (FSW) methods are known from the prior art, in which a rotating stirring pin penetrates into the two materials to be connected, in which it is kept rotating to generate heat. These methods can be carried out as spot welding or line welding methods, wherein the machines developed for this purpose are preferably designed for the respective welding method and, due to specific requirements, cannot usually be used interchangeably for the two welding methods.

[0004] Since in friction stir welding of plastics the welding process is completely controlled by the penetration and rotation of the tool, this often leads to the formation of porous areas in or around the weld nugget. Large bubbles may also form, which are caused by thermal contraction during the cooling phase.

[0005] CN 109967858 A discloses a friction stir welding device for producing linear welds. A stirring pin is guided in a simple jacket, which is located on the plastic material to be welded. The jacket is surrounded by a heating device.

[0006] CN113020776 also discloses a friction stir welding device for producing linear welds, wherein a stirring pin is integrally formed with a tool head.

[0007] DE102014112683A1 discloses a hybrid joining technology in which friction and ultrasonic energy are applied to the workpiece simultaneously. A central horn emits ultrasonic waves into the workpiece. The horn is surrounded by an annular friction tool, which is in frictional contact with the tool.

[0008] WO 2022 / 045171 A1 discloses a friction stir welding device for spot welding. In this document, the stirring pin is surrounded by an inner sleeve and an outer sleeve. The heat generated for the welding process in this device is only by friction. This tool is only used for spot welding and is therefore far from being used for linear welding, because the inner sleeve may also penetrate the material to be welded, thereby preventing linear movement. Similar spot welding methods are disclosed in documents WO2022045171A1, EP3909714A1 and WO2015145251A1.

[0009] KR20070061937A also describes a friction stir welding device for spot welding. In this case, two metal layers are to be welded together. Therefore, since the upper layer must also be made of metal, the device cannot be moved longitudinally. Summary of the invention

[0010] The object of the present invention is to overcome these problems of the prior art and to provide a friction stir welding device for producing linear or spot welded joints of plastic sheets on metal or plastic substrates.

[0011] This object is achieved by a stir friction welding device, which is used to produce a point or linear weld joint between a plastic plate or a plastic molded part (hereinafter referred to as a plastic plate, although the present invention also includes the welding of plastic molded parts) and a metal or plastic substrate, the device comprising a welding head having a rotatable or oscillating stirring pin and a sleeve surrounding the stirring pin, wherein a reservoir for receiving material displaced by the stirring pin is provided between the sleeve and the stirring pin, wherein the reservoir is preferably defined by a step formed integrally with the sleeve or by a reservoir sleeve provided between the sleeve and the stirring pin (alternatively, the stirring pin may also have a step, etc.), wherein the stir friction welding device also includes a heating device for directly heating the stirring pin.

[0012] By means of the reservoir according to the invention, it is possible to ensure the production of an extremely tight weld joint right away, even in a linear welding method. The reservoir prevents the material displaced by the stirring pin (from the plastic sheet or the metal or plastic substrate, respectively) from expanding freely outwards due to the pressure prevailing in the reservoir, thereby preventing subsequent inclusion of air. According to the invention, the pressure during the formation of the weld joint can thus be adjusted by means of the outer jacket or reservoir sleeve, thereby further compensating for shrinkage effects, whereas in the prior art the welding pressure is generated entirely by the pressing force of the tool on the substrate.

[0013] Overall, it is thus possible to produce significantly tighter weld joints than was previously possible in the prior art. In particular, no additional seals are required which, over time, could become porous or cause leaks due to settling or swelling.

[0014] When using a multi-part jacket system with a reservoir jacket, it may be particularly prone to catching excess material because it may be designed to be movable relative to the jacket. However, the reservoir jacket cannot be located under the jacket and therefore cannot penetrate into the plastic sheet, as this would not make it possible to form a linear weld joint. In contrast, a jacket with a step is easier to manufacture and control. In particular, because the system has a one-piece jacket with a step, it is easier to provide a through hole or access point for the electrical connection for the heated stirring pin.

[0015] According to the present invention, the friction stir welding device also includes a heating device for directly heating the stirring pin. Compared with the prior art, the process heat does not need to be generated by friction between the tool and the workpiece, because it is provided by the already heated stirring pin. According to the present invention, the friction heat is therefore only used to adjust (i.e. preheat) the workpiece. The temperature to which the stirring pin is heated can be selected according to the material of the workpiece, the feed speed of the welding head, etc., and can be adjusted by the control unit as required. Regarding CN 109967858 A, it should be noted that this document teaches heating the shoulder arranged around the welding head, thereby only pre-adjusting the workpiece, without directly heating the stirring pin, and therefore the process heat must be generated by the friction of the stirring pin. In contrast, in the present invention, the jacket can even be cooled while the stirring pin is directly heated.

[0016] The advantage of a directly heated stirring pin is therefore that the required process heat does not have to be generated solely by friction. Thus, according to the invention, new fields of application can be opened up, since process heat such as for plastic welding can only be achieved with difficulty by friction, taking into account the very low coefficient of friction of plastics and the insulating effect of plastics. Furthermore, due to the directly heated stirring pin, lower rotational speeds can be used, which counteracts the shearing effects within the weld material and thus enables the material to move better around the stirring pin.

[0017] It is important to emphasize that the reservoir and the directly heated stirring pin exhibit a synergistic effect, as the material in the reservoir can be maintained at the operating temperature.

[0018] In order to achieve direct heating of the rotating or oscillating stirring pin, respectively, the heating device can include a heating cylinder arranged inside the stirring pin, which is preferably in contact with an energy source located outside the stirring pin via a sliding contact. Alternatively, the heating device can include an induction coil arranged around the stirring pin and an inductively heatable material inside or on the stirring pin. These two embodiments are particularly preferably used to achieve heating of the stirring pin itself even during rotation or oscillation, respectively. In a further variant, the heat transfer medium can pass through the stirring pin, although this will be extremely complicated.

[0019] Particularly preferably, the friction stir welding device also includes a manually operated or controlled linear feed device for linearly moving the welding head during the welding process. In practice, it has been found that the friction stir welding device according to the present invention is particularly suitable for producing tight linear weld joints, for example, firmly attaching a cover to a housing.

[0020] Furthermore, it is preferred that the welding head, preferably the housing, comprises a through hole leading to the reservoir for external material supply. The through hole can be used in particular to further adjust the welding pressure by supplying welding additives.

[0021] In another preferred embodiment, the friction stir welding device includes a coupling that selectively couples the stirring pin to the outer sleeve and / or the reservoir sleeve to transmit torque. Although it is generally preferred that the outer sleeve is placed on the plastic plate without rotating, it can be provided that the outer sleeve or the reservoir sleeve can rotate to promote mixing of materials in the reservoir or to follow a predefined contour when using a profiled outer sleeve. According to the present invention, the coupling (so-called stop lock function) can fix the outer sleeve to prevent it from rotating. According to an embodiment, the stirring pin can also be coupled to one or both of the above-mentioned sleeves to allow them to rotate with the stirring pin.

[0022] It is further preferred that the stirring pin has a section facing the plastic plate, at least a part of which is formed as a conveying screw. This allows the material to be conveyed from the reservoir to the connection zone by rotation. In this embodiment, the jacket preferably has a narrowing section facing the plastic plate so that the reservoir does not directly contact the plastic plate. However, in other embodiments, this is not mandatory, which means that a section with a conveying screw can also be combined with all other embodiments.

[0023] In another aspect, the present invention relates to a friction stir welding method using the friction stir welding device according to one of the above embodiments, the method comprising the following steps:

[0024] - Placing the plastic sheet on a metal or plastic substrate,

[0025] - inserting the stirring pin into the plastic sheet until it penetrates the plastic sheet and at least contacts the metal or plastic substrate, and positioning the jacket on the plastic sheet (this can also be done before inserting the stirring pin),

[0026] - When the stirring pin penetrates the plastic sheet and contacts at least the metal or plastic substrate, a welding head with a rotating or oscillating stirring pin is moved by a linear drive to produce a linear weld joint.

[0027] It is further preferred that the stirring pin is heated immediately during this movement.

[0028] The friction stir welding method according to the present invention has the same advantages as the friction stir welding device described above. In particular, when the welding additive is introduced into the reservoir through the through hole during the movement of the welding head, the welding pressure can be further adjusted to form a linear welding joint or a sealed opening.

[0029] The welding method is particularly advantageous when the metal or plastic substrate is a housing having an opening and the plastic sheet is a cover, wherein the welding method comprises the following steps:

[0030] -Put the cover over the opening, and

[0031] - A closed linear weld joint (eg, a circular or diamond-shaped weld joint) is formed around the opening to securely seal the opening with the cover, which means that the opening is located within the circular weld joint.

[0032] This welding method enables the opening to be closed particularly tightly without the need for additional measures.

[0033] The friction stir welding method is particularly advantageous when the plastic sheet and / or the plastic substrate is made of polyamide, preferably PA6 GF30, and the optionally present metal substrate is made of aluminum, preferably cast aluminum, particularly preferably cast aluminum EN AC44200. It should be understood that the friction stir welding method according to the invention is not limited to these materials and can also be applied to other materials, such as aluminum EN AW6082 for the metal substrate or polycarbonate for the plastic sheet or the plastic substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] These and further advantageous embodiments of the method according to the invention will be explained in more detail below by means of the drawings.

[0035] Figure 1 A friction stir welding device according to the invention is shown in a schematic side view.

[0036] Figure 2 Show Figure 1 The friction stir welding device produces the weld joint between the cover and the shell.

[0037] Figure 3 A variant of the friction stir welding device according to the invention is shown which has a multi-part sleeve system.

[0038] Figure 4 Show Figure 1 Another variant of the friction stir welding device has a stirring pin, the tip of which is embodied as a conveying screw.

[0039] Figure 5 A first embodiment of a heating device for a friction stir welding apparatus according to the present invention is shown.

[0040] Figure 6 A second embodiment of the heating device of the friction stir welding apparatus according to the present invention is shown.

[0041] Figures 7a to 7c The following diagram shows the sequential states during the use of the friction stir welding device according to the present invention.

[0042] Figure 8a and Figure 8b Another variant of the friction stir welding device according to the invention is shown in a front view and a side view, which has a profiled jacket.

[0043] Figure 9a and Figure 9b Another variant of the friction stir welding device according to the invention is shown in a front view and a side view, which has an asymmetrical profile jacket. DETAILED DESCRIPTION

[0044] Figure 1 A friction stir welding device 1 is shown with a welding head 2. The friction stir welding device 1 is used to produce a linear weld joint 31 ( Figure 2 ), for example, an elongated weld seam. However, the plastic sheet 3 does not need to be completely flat, so it can also be generally referred to as a plastic molding. The metal or plastic substrate 4 can be, for example, another plate or a solid. The weld joint 31 produced by the friction stir welding device 1 is particularly tight after production to ensure that the weld joint 31 between the plastic sheet 3 and the metal or plastic substrate 4 can be used in the fields of automotive engineering, aerospace technology or so-called "white appliances".

[0045] In particular, the plastic plate 3 can be used as a cover, and the metal or plastic substrate 4 can be a housing, such as Figure 2 As shown. The housing may have an opening 30, and the cover may be positioned to cover the opening 30. The friction stir welding device 1 is used to form a tight weld joint 31 around the opening 30, thereby tightly sealing the opening 30. Figure 2 In the figure, the weld joint 31 is shown as a circle; however, it can also take the form of a diamond shape or a similar configuration. Moreover, the invention is not limited to this application and can generally only produce linear, i.e. non-circumferential weld joints 31. Furthermore, the workpiece does not necessarily have to be a combination of a housing and a cover.

[0046] In order to obtain a linear advancement of the welding head 2, a holding device of the welding head 2 (not shown further) can be inserted into the tool holder 5 of the friction stir welding device 1, such as Figure 1As shown. For example, the tool holder 5 can be moved along the track system 6 of the friction stir welding device 1 to allow the welding head 2 to move in a plane defined by the x-direction and the y-direction shown. This plane is generally parallel to the plastic sheet 3 or the metal or plastic substrate 4. In addition to this linear advancement, the friction stir welding device 1 can also include a device for lowering and raising the welding head 2 or a part of the welding head 2 in the z-direction (i.e., toward the plastic sheet 3 or the metal or plastic substrate 4).

[0047] It should be understood that the embodiment of linear advancement shown is only illustrative and can generally be achieved in different ways, such as by a rotational motion. The linear advancement can also be manually operated, such as by one or more hand wheels, or the linear advancement can be automatically controlled, so that the friction stir welding device 1 can be operated as a CNC (computer numerical control) machine.

[0048] In alternative embodiments, the friction stir welding device 1 can also be used for spot welding, so linear advancement is not necessarily required. For example, the workpiece can be moved to produce additional welds at different locations on the workpiece. In other embodiment variations, a linear drive can be used during spot welding to automatically or manually transfer the welding head 2 to a second position where another weld is formed. Before moving to the next weld, the welding head 2 or the stirring pin is raised to avoid the production of a linear weld.

[0049] To produce the weld joint 31, the welding head 2 comprises a rotatable or oscillating stirring pin 7 which can be lowered in the direction of 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, wherein no relative movement of the stirring pin 7 relative to the tool holder 5 is required, such as Figure 1 As shown, or by the relative movement of the stirring pin 7, which can be achieved by Figure 3 The spring 8 shown in the example is started. The stirring pin 7 can be made of metal or ceramic and, if necessary, can have a coating, particularly a Teflon coating. In addition, the outer contour of the stirring pin 7 can have a profile or a recess.

[0050] In order to ensure that the material displaced by the stirring pin 7 from the plastic plate 3 or the metal or plastic substrate 4 forms a particularly tight weld joint 31, the welding head 2 also includes a jacket 9 surrounding the stirring pin 7. The jacket 9 preferably has a flat resting surface 10 facing the plastic plate 3, so that the jacket 9 can be moved along the plastic plate 3 during linear advancement while the stirring pin 7 is inserted. In this way, the jacket 9 can seal the area around the stirring pin 7. The jacket 9 can be made of metal or ceramic and can have a coating if necessary. For example, it can be designed to be rotationally symmetrical or shaped to form a fillet weld. See also below Figures 8a to 9b .

[0051] In order to capture the material displaced during the penetration of the stirring pin 7 into the plastic plate 3 or the metal or plastic substrate 4, a reservoir 11 is provided at the lower end between the jacket 9 and the stirring pin 7. The term "lower end" refers to the end facing away from the tool holder 5 or facing the plastic plate 3.

[0052] According to the present invention, the reservoir 11 can be configured in various ways. Figure 1 As shown, the lower end of the jacket 9 may have an extended step that is limited upward to form a reservoir 11. The step has a corresponding height to capture a predetermined amount of displaced material. The step may also be configured to be narrowed, such as Figure 4 As shown, the reservoir 11 is located above the step. In this case, the reservoir 11 can be surrounded by the stirring pin 7 that expands upwards between the outer sleeve 9 and the stirring pin 7.

[0053] like Figure 3 As shown, a reservoir sleeve 12 arranged 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 by defining a space between the outer sleeve 9 and the stirring pin 7 above. In this embodiment, a relative movement between the reservoir sleeve 12 and the outer sleeve 9 and preferably also the stirring pin can be provided to adjust the height of the reservoir 11, that is, to set the distance between the resting surface 10 of the outer sleeve 9 and the lower end of the reservoir sleeve 12, which can be achieved by Figure 3 The reservoir jacket 12 can also be made of metal or ceramic material and can optionally have a coating.

[0054] Furthermore, the relative movement between the outer sleeve 9 and the stirring pin 7 in the z direction can be achieved by, for example Figure 1 and Figure 3 This is achieved by means of the spring 14 schematically shown in FIG. Figure 1 In the embodiment, for example, it can be arranged that the stirring pin 7 and the tool holder 5 cannot move relative to each other in the z direction, while the stirring pin 7 and the sleeve 9 can still move relative to each other in the z direction through the spring 14.

[0055] Figure 3 It is shown that the welding head 2 can provide individual springs 8, 13, 14 for the stirring pin 7 as well as the outer sleeve 9 and the reservoir sleeve 12 to allow a relative movement of all these elements in the z direction relative to each other and relative to the tool holder 5. For example, the relative movement can be actuated electronically, hydraulically or purely mechanically, wherein the springs 8, 13, 14 can be used to provide a restoring force, or they can be omitted, for example if the selected drive does not require a restoring force. It should be understood that it is not strictly necessary to provide a relative movement of all these elements relative to each other and relative to the tool holder 5 in the z direction, so that lowering the tool holder 5 results in the same movement of the individual elements, for which no relative movement in the z direction relative to the tool holder 5 is provided.

[0056] As previously mentioned, the stirring pin 7 can be rotated and / or oscillated around an axis A extending in the z direction to produce the weld joint 31. This rotational or oscillating motion can usually be adjusted by the friction stir welding device 1 or by the user. For example, the rotational or oscillating speed can be selected depending on the material of the plastic plate 3 and the metal or plastic substrate 4, however, this is not strictly required, because in many embodiments of the method according to the invention, the main heat is not generated by the rotational or oscillating motion, but by the heating device of the stirring pin 7, which will be explained in more detail below.

[0057] The outer sleeve 9 and the reservoir sleeve 12 do not usually perform a rotational or oscillating movement around the axis A extending in the z direction; however, it can be arranged that the rotational or oscillating movement of the stirring pin 7 can be selectively transmitted to the outer sleeve 9 and / or the reservoir sleeve 12 via the coupling. This may be beneficial to start a mixing movement in the reservoir 11.

[0058] Back to Figure 1 , it can be seen that the outer sleeve 9 has a through hole 15 leading to a reservoir for supplying external material. In particular, a welding additive can be introduced into the reservoir 11 to give particularly preferred properties to the produced weld joint 31. At the end of the through hole facing away from the reservoir 11, an extruder (not further shown) can be connected, or a plastic line can be provided to convey the welding additive into the reservoir 11. In this way, the welding pressure can be additionally adjusted.

[0059] Figure 1 The through hole 15 of the one-piece jacket 9 shown can also be embodied in Figure 3 In the embodiment of the present invention, the through hole 15 preferably only passes through the outer sleeve 9. However, optionally, the through hole 15 can also extend at least partially through the reservoir sleeve 12.

[0060] Figure 4 A particularly preferred development is shown, which can preferably be used in combination with a through hole 15. At this point, it should be noted 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 d1. On the second section, a conveying screw F is at least partially present, which means that it has at least one inclined groove-shaped indentation extending in the z direction. This enables the material to be introduced particularly effectively into the penetration site formed by the stirring pin 7 in the plastic plate 3 or in the metal or plastic substrate 4. As shown in the figure, the lower end of the second section is preferably not formed as a conveying screw F, but has a basically cylindrical or truncated conical shape to better penetrate into the plastic plate 3 or into the metal or plastic substrate 4.

[0061] exist Figure 4In the embodiment shown, the reservoir 11 is preferably formed by a jacket 9 having a narrowing step 16 at the lower end, whose inner diameter is substantially d2 and surrounds the second section of the stirring pin 7. Above the step 16, the inner diameter of the jacket 9 is substantially d1. Therefore, in this embodiment, the reservoir 11 is not directly located on the surface of the plastic plate 3, but is located at a certain distance above it. In another embodiment not shown. The stirring pin can also have a step, and the jacket can have a cylindrical inner wall.

[0062] Figure 1 It is further shown that the stirring pin 7 can include a heating device 17 for directly heating the stirring pin 7 and bringing it to a predetermined welding temperature. Therefore, according to the invention, heat can thus be introduced directly into the workpiece via the stirring pin 7. Figure 1 In the embodiment of , it is schematically shown that the stirring pin 7 can have two openings extending parallel to the z-axis, in which a heating cylinder that converts electrical energy into heat can be arranged.

[0063] Figure 5 A specific embodiment of the heating device 17 is shown in which two sliding contacts 18 are provided, which are guided through the jacket 9 and each contact a ring-shaped contact point 19 on the stirring pin 7. In other variants, the sliding contacts can also be guided over the jacket 9 to the contact points 19, which means that the jacket 9 does not necessarily have to be perforated. The contact points 19 are in turn connected to one or more heating cylinders 20, which heat the stirring pin 7. By means of this embodiment, electrical energy can be transferred to the interior of the stirring pin 7 even when the stirring pin 7 is rotating or oscillating.

[0064] Figure 6 An embodiment is shown in which an induction coil 21 is arranged around the stirring pin 7. When an alternating current is applied to the induction coil 21 via the wire 22, an alternating magnetic field is generated, which can heat the stirring pin 7 when the stirring pin 7 contains an inductively heatable material (i.e., an electrically conductive material). In the embodiment shown, the stirring pin 7 contains a heat conductor 23 in its interior. Since the induction coil 21 is not directly arranged in the stirring pin 7 in this embodiment, it is generally considered that the welding head 2 includes a heating device 17 for directly heating the stirring pin 7 to bring it to a predetermined welding temperature.

[0065] Furthermore, the stirring pin 7 may have a friction attachment 25 at its lower end, which attachment faces the plastic plate 3, such as Figure 5 This is particularly advantageous when welding processes are carried out on metal substrates 4, since here the stirring pin 7 can be additionally reinforced at particularly stress-bearing points.

[0066] Reference Figure 7a , Figure 7b and Figure 7c , a welding method using the welding head 2 described above will be described. Figure 7a , first provide a workpiece, that is, place a plastic plate 3 on a metal or plastic substrate 4. Then position the welding head 2 above the plastic plate 3 and move it in the direction of the plastic plate 3 until the resting surface 10 of the stirring pin 7 and / or the jacket 9 rests on the plastic plate 3. At this point, the stirring pin 7 is preferably already heated by the heating device 17.

[0067] according to Figure 7b Then the stirring pin 7 penetrates into the plastic plate 3 and passes through the plastic plate 3 until the stirring pin 7 contacts the metal or plastic substrate 4 or penetrates the metal or plastic substrate 4 to a predetermined depth. Figure 7a The status moves to Figure 7b During the state, 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 in contact with the metal or plastic substrate 4 to modulate it for welding.

[0068] Obviously, due to the stirring pin 7 piercing into Figure 7b In the state shown, material is displaced from the plastic sheet 3 and, optionally, material is also displaced from the metal or plastic substrate 4. The material is captured by the reservoir 11. However, since the reservoir 11 continues to hold the material under pressure, a predetermined or adjustable welding pressure will exist. If the welding head 2 includes a reservoir sleeve 12, the amount of material captured 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 feeding the material into the reservoir 12 via the through hole 15.

[0069] like Figure 7c As shown, the welding head 2 with the rotating or oscillating and optionally heated stirring pin 7 can now be moved in the welding direction S using a linear drive to form a linear weld joint 31 between the plastic plate 3 and the metal or plastic substrate 4. It is obvious that, as seen in the welding direction S, a weld structure 24 is being formed behind the stirring pin 7, which means an elongated weld seam connecting the plastic plate 3 to the metal or plastic substrate 4. After the stirring pin 7 is removed from the plastic plate 3, this weld structure forms the weld joint 31.

[0070] Figure 8a and Figure 8b A variant of a wedge-shaped jacket 9 is shown. The tip of the wedge faces the workpiece and is optionally rounded. Figure 1 and Figure 3 Compared with the rotationally symmetrical jacket 9 in FIG. 1 , this jacket is an example of a symmetrically molded jacket 9. In other words, Figure 8a and Figure 8bThe rest surface 10 of the jacket 9 in FIG. 1 has two flat sections 26 which are arranged symmetrically and positioned at an angle about the axis A. For the welding process, the two sections 26 are arranged so that the welding direction S is parallel to the sections 26. Furthermore, during the welding process, an imaginary cutting line of the two sections 26 is perpendicular to the axis A and parallel to the welding direction. Such a jacket 9 is particularly designed for producing fillet welds during the welding process.

[0071] Figure 9a and Figure 9b A variant of a jacket 9 is shown, which is formed by two wedges offset in the z direction, whose tips face the workpiece and are possibly rounded. This jacket 9 is an example of an asymmetrically formed jacket. In other words, the resting surface 10 of this jacket 9 comprises two first sections 27 and two second sections 28, each of which is a flat surface. At the lower end facing the workpiece, the two first sections 27 are symmetrically arranged and angled around the axis A, while the second sections 28 are also symmetrically arranged and angled around the axis A (usually at the same angle as the first sections 27). Although both the first sections 27 and the second sections 28 are configured symmetrically relative to each other, the imaginary cutting lines of the first sections 27 or the second sections 28 are spaced apart in the z direction, thereby forming two offset wedges. Such a jacket 9 is particularly capable of producing fillet welds or other weld shapes during welding.

[0072] Although Figures 8a to 9b The embodiment shown in FIG. 1 is described in conjunction with a conveying screw F and an internal reservoir 11, but may also be combined with a Figure 1 and Figure 3 The reservoir 11 shown in the embodiment uses a wedge-shaped or other shaped outer sleeve 9.

Claims

1. A friction stir welding device (1) for producing a point or linear weld joint (31) between a plastic plate (3) or a plastic molding and a metal or plastic substrate (4), the friction stir welding device (1) comprising a welding head (2) with a rotatable or oscillating stirring pin (7) and a jacket (9) surrounding the stirring pin (7), A reservoir (11) is provided between the outer sleeve (9) and the stirring pin (7) for receiving material displaced by the stirring pin (7), wherein the reservoir (11) is preferably defined by a step formed integrally with the outer sleeve (9) or by a reservoir sleeve (12) provided between the outer sleeve (9) and the stirring pin (7), Features The friction stir welding device (1) further comprises a heating device (17) for directly heating the stirring pin (7).

2. The friction stir welding device (1) according to claim 1, wherein the heating device (17) comprises a heating cylinder arranged in the stirring pin (7), and the heating cylinder (7) is preferably in contact with an energy source arranged outside the stirring pin (7) through a sliding contact (19).

3. The friction stir welding device (1) according to claim 1, wherein the heating device (17) includes an induction coil (21) arranged around the stirring pin (7) and an inductively heatable material located inside or on the stirring pin (7).

4. The friction stir welding device (1) according to any one of claims 1 to 3, wherein the friction stir welding device (1) comprises a manually operated or controlled linear feed device for linearly moving the welding head (2) during the welding process.

5. The friction stir welding device (1) according to any one of claims 1 to 3, wherein the welding head (2), preferably the outer casing (9), has a through hole (15) leading to the reservoir (11), and the through hole (15) is used to supply external material or to discharge material.

6. The friction stir welding device (1) according to any one of claims 1 to 5, further comprising a coupling which selectively couples the stirring pin (7) with the outer sleeve (9) and / or the reservoir sleeve (12) to transmit torque.

7. The friction stir welding device (1) according to any 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 formed as a conveying screw (F).

8. A friction stir welding method using the friction stir welding device (1) according to any one of claims 1 to 7, the method The following steps are involved: - placing the plastic sheet (3) or the plastic moulding on the metal or plastic substrate (4), - inserting the stirring pin (7) into the plastic plate (3) or the plastic moulding until it penetrates the plastic plate (3) and at least contacts the metal or plastic substrate (4), and positioning the sleeve (9) on the plastic plate (3) or on the plastic moulding; - Using a linear drive to move the welding head (2) with the rotating or oscillating stirring pin (7) to produce a linear weld joint (31) while the stirring pin (7) penetrates the plastic plate (3) or the plastic molding and at least contacts the metal or plastic substrate (4).

9. The friction stir welding method according to claim 8, wherein the metal or plastic substrate (4) is a housing having an opening (30), and the plastic plate (3) or the plastic molded part is a cover, the method The following steps are involved: - placing the cover over the opening (30), and - forming a closed linear weld joint (31) around the opening (30) to tightly seal the opening (30) to the cover.

10. The friction stir welding method according to claim 8 or 9, wherein the plastic sheet and / or the plastic substrate is made of polyamide, preferably PA6 GF30, and the optionally present metal substrate is made of aluminum, preferably cast aluminum, particularly preferably cast aluminum EN AC44200.

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