Method for producing a weld seam by means of a friction stir welding tool guided automatically by a machine, friction stir welding tool, friction stir welding device, and computer program product

Abstract

The invention relates to a method for producing a weld seam (32) by means of a stationary-shoulder (9) friction stir welding tool (8) guided automatically by a machine (2) along a join (10), the method comprising, inter alia, the step of supplying additional material by means of a feed device (19) for the additional material beyond the friction stir welding tool (8) into a sealed shaping chamber (18) in a plasticised state of the additional material at a pressure which can be set independently of the speed of rotation of a rotating stirring pin (13) and the feed rate of a feed device (19). The invention further relates to a friction stir welding tool (8), an associated friction stir welding device (1) and a corresponding computer program product.

Description

[0001] Method for producing a weld seam using a friction stir welding tool automatically guided by a machine, friction stir welding tool, friction stir welding device and computer program product

[0002] The invention relates to a method for producing a weld seam using a friction stir welding tool with a stationary shoulder, automatically guided by a machine along a joint. The invention also relates to an associated friction stir welding tool, an associated friction stir welding device, and a corresponding computer program.

[0003] The method for producing a weld seam using a friction stir welding tool with a stationary shoulder, automatically guided by a machine, deals with friction stir welding. Friction stir welding itself is described in DIN EN ISO 4063 under process number 43. Friction stir welding is also referred to as FSW welding (English: Friction Stir Welding). In a basic application, two separate components, for example in a butt joint with two opposing end faces, are placed together and held in position by means of a clamping device. A friction stir welding tool comprises a stirring rod that rotates during the welding process and a shoulder surrounding the rotating stirring rod, which covers the plasticized material from above during welding in the form of a ring-shaped covering surface surrounding the stirring rod.The shoulder can either be designed to rotate with the stir bar or, as a stationary shoulder, not rotate with the stir bar. Stationary shoulder friction stir welding is also known as SSFSW welding (Stationary Shoulder Friction Stir Welding).

[0004] In the first process step, the stir bar of the friction stir welding tool is set in rotation and pressed against at least one of the two clamped components in the immediate vicinity of the joint. In the area of ​​the contact surfaces between the rotating stir bar and the component, heat is generated due to friction effects, which plasticizes the at least one component in the area of ​​the rotating stir bar. Due to the plasticization of the component material, the rotating stir bar can penetrate deeper into the component.The rotating stirrer is then guided along the joint between the two components to be welded in a direction perpendicular to its axis of rotation. During this process, material from both components is successively plasticized, mixed in the joining zone, and then solidified again by cooling in the direction of movement behind the rotating stirrer, forming the finished weld. Finally, at the end of the weld or further away from the completed weld, the rotating stirrer is withdrawn from the welded components, removing the plasticized material from the area around the stirrer.

[0005] DE 10 2014 115 535 B3 describes a friction stir welding tool with a non-rotating shoulder, which has a first workpiece contact surface for contacting a workpiece to be welded, and at least one rotating pin, wherein the pin and shoulder define a gap between them and the wall of the pin and / or shoulder defining the gap has a first axially acting feed screw structure, and wherein the friction stir welding tool has a material feed opening located away from the first workpiece contact surface and opening into the gap. The document also describes an associated friction stir welding method in which an additional material is introduced into a gap between a non-rotating shoulder, which contacts the workpiece with a first workpiece contact surface, and a rotating pin, and transported to the workpiece.

[0006] The additional material is transported by the axially acting screw conveyor and also plasticized at the screw conveyor. The movement required for transporting the additional material is achieved by rotating the pin. A disadvantage of this design is that the pin's rotational speed, as a crucial process parameter for plasticizing the workpieces to be welded, must be precisely calibrated. Therefore, the conveying conditions for the additional material cannot be controlled or regulated independently. For example, if a larger quantity of additional material needed to be conveyed into the pin's plasticizing zone, a correspondingly higher pin rotational speed would be required, which, however, could negatively impact the process conditions within the pin's plasticizing zone.Therefore, it has already been suggested to design the rotation of the pin and a rotation of a separate extruder screw for the transport and plasticizing of the additional material independently of each other.

[0007] DE 10 2022 112 431 B3 describes a device for friction stir welding of workpieces by supplying a filler material, comprising a welding pin rotating in a stationary shoulder, wherein the device has on the workpiece-away upper side of the stationary shoulder an extruder rotating coaxially around the welding pin, which forms an annular extrusion chamber with the upper side of the shoulder, having a buttress, wherein the rotation of the welding pin and the rotation of the extruder are decoupled from each other, wherein the stationary shoulder has an opening through which the filler material is fed into the extrusion chamber and wherein the annular extrusion chamber has several slots distributed around its inner circumference for receiving the buttress.

[0008] With this design, the conveying capacity of the extruder and the plasticizing capacity for the filler material can be adjusted independently of the rotating welding rod, however, the pressure in the extrusion chamber cannot be adjusted independently of the conveyed quantity of filler material.

[0009] The object of the invention is to create a method for producing a weld seam by means of a friction stir welding tool with a stationary shoulder automatically guided by a machine along a joint, with which a pressure in a forming chamber of the friction stir welding tool can be set independently of the quantity of filler material supplied.

[0010] The problem is solved by a method for producing a weld seam using a friction stir welding tool with a stationary shoulder guided by a machine along a joint, comprising the steps:

[0011] - Immersion of a stirring pin of the friction stir welding tool into at least one component with an immersion pressure directed towards the component in the rotational direction of the stirring pin, in order to plasticize component material in a plasticizing zone in the area of ​​the joint by rotating the stirring pin until the stationary shoulder of the friction stir welding tool rests against the component.

[0012] - during automatic movement of the friction stir welding tool along a path on which the joint runs, by automatically controlling a machine guiding the friction stir welding tool, applying such a process contact force of the friction stir welding tool to the component that a forming chamber sealed against the escape of plasticized material is formed between the component and the stationary shoulder,

[0013] - during automatic movement of the friction stir welding tool along the path on which the joint runs, a filler material is fed by means of a conveying device for the filler material over the friction stir welding tool into the sealed forming chamber in a plasticized state of the filler material with a pressure that can be adjusted independently of the speed of the rotating stir stick and the conveying capacity of the conveying device.

[0014] The method for producing a weld seam using a friction stir welding tool with a stationary shoulder, automatically guided by a machine, can be used, for example, to weld a first component to a second component. The two components can be placed together in a butt joint with two opposing end faces and held in position by means of a clamping device. The friction stir welding tool comprises the stirring pin, which rotates during the welding process, and a stationary shoulder surrounding the rotating stirring pin. This shoulder covers the plasticized material from above during welding, forming a ring-shaped surface around the stirring pin.If the two components are not perfectly flush against each other, an undesirable gap forms between them. This gap can be filled by the filler material additionally introduced into the plasticizing zone of the friction stir welding tool. Such gaps are generally undesirable, but often cannot be completely prevented. Along a joint between the first and second components, the gap width and / or depth may also vary.

[0015] The gap volume must be additionally filled with plasticized material during the welding process if a weld surface that is recessed from the surface of the components to be joined is to be prevented. Accordingly, a corresponding volume of filler material must be supplied to supplement the plasticized material of the components, so that a weld surface that is flush with the surface of the components to be joined, or, if desired, even a raised weld surface, can be produced. Therefore, the amount of filler material must be adjusted according to the gap volume to ensure that enough plasticized material is available for filling and, if necessary, for raising the weld.For example, it is also advantageous if the pressure with which the filler material is introduced into the forming chamber can be changed, i.e., adjusted differently, during the weld formation process, while the friction stir welding tool automatically moves along the joint. The principles described for butt joints also apply, analogously, to corner joints between two components or other types of joints. A gap between two components to be welded can even be deliberately created by appropriately positioning the first and second components in order to introduce a desired quantity of filler material into the weld to be produced.

[0016] However, introducing filler material into the forming chamber can also be useful for other purposes. For example, it can be used to create a weld bead reinforcement. This means that the weld shoulder does not completely cover the joint flush with the surfaces of the components, thus creating a weld surface that is flush with the first and / or second component and coincides with the surface plane of the first and / or second component. Instead, the weld connecting the first and second components is intentionally designed to protrude above the surface plane of the first and / or second component, forming, for example, a raised bead on the components. In this case, the weld shoulder has an exit opening.Together with the surfaces of the first component and / or the second component, it forms a groove-shaped flow channel, the cross-sectional contour of which determines the subsequent shape of the weld reinforcement. Such a weld reinforcement need not necessarily be located exclusively at a joint between two components; rather, it can also be applied to a single component, for example, to stiffen an area of ​​the component by selectively forming ribs using the weld reinforcement. In such a case, the joint is formed only locally in the area of ​​the plasticizing zone around the stir bar by the insertion of the stir bar of the friction stir welding tool.

[0017] The filler material can have the same material properties as the at least one component to which the weld is applied. However, the filler material can also be made of a different material and therefore have different material properties than the at least one component to which the weld is applied.

[0018] In the inventive method, the contact force of the standing shoulder on the at least one component is always chosen to be so high that the molding chamber bounded by the standing shoulder and the component remains sealed at the respective set pressure in the molding chamber and no plasticized material escapes from the molding chamber in its plasticized state.

[0019] In the prior art, it is generally tolerated if a small amount of additive material introduced into the plasticizing zone escapes to the outside through a minor gap between the stationary shoulder and the component. The inventive process incorporates a completely sealed molding chamber, preventing any uncontrolled escape of additive material.

[0020] The inventive method thus makes it possible to carry out repairs on components, for example by filling surface damage or surface voids with the additive material using the described friction stir welding process.

[0021] Another application is, for example, 3D metal printing, where, using the method according to the invention, additional material can be successively generated, i.e., built up, to desired geometric structures by friction stir welding using the described friction stir welding process. An advantage is that, by designing the stationary shoulder, which can, for example, be provided with lateral cheeks, the previously printed layer can be laterally limited, so that an additional new layer can be applied to the previously printed layer without the plasticized material escaping uncontrollably laterally. This allows the lateral outer contour of the built-up seam to be produced with a more uniform shape than was possible with previous 3D metal printing methods using conventional FSW tools that operate without a pressure chamber according to the invention.

[0022] Furthermore, cast components, in particular Gigacast components, can be processed using the method according to the invention. For example, unwanted stress cracks in cast components, especially Gigacast components, can be repaired by applying filler material into the stress cracks using the method according to the invention. Alternatively, two separate cast parts, which are intended to form a Gigacast component, for example, can be welded together using the method according to the invention. Cast components produced by die casting, in particular Gigacast components, can also be additionally provided with ribs or other applied structures by friction stir welding using the method according to the invention.

[0023] Notwithstanding the specific design of a seam reinforcement, regardless of the amount of additional material supplied, it may also be advantageous if the pressure in the forming chamber can be adjusted using the inventive method, so that the pressure on the plasticizing zone can be influenced, in particular improved, in order to affect the seam properties.

[0024] According to the invention, in the method, during an automatic movement of the friction stir welding tool along the path on which the joint runs, an additive material is fed by means of a conveying device for the additive material over the friction stir welding tool into the sealed forming chamber in a plasticized state of the additive material with a pressure that can be adjusted independently of the speed of the rotating stir stick and the conveying capacity of the conveying device.

[0025] The inventive method uses a friction stir welding tool that has a stationary shoulder. Accordingly, the stationary shoulder does not rotate with the stir bar, but remains at least substantially stationary relative to the components to be welded. However, it is possible to reorient the stationary shoulder, for example, if the weld joint is not straight, but has a curved section, and the stationary shoulder is to remain in the same orientation relative to the weld seam.

[0026] The stationary shoulder covers the plasticizing zone from above along the entire weld seam and seals the forming chamber against the at least one component onto which the stationary shoulder is pressed. The stationary shoulder, with its respective contour shape, thus forms the surface of the resulting weld seam. The stationary shoulder contacts the first component and / or the second component during the automatic movement of the friction stir welding tool or during the automatic movement of the rotating stir bar of the friction stir welding tool along the joint to be welded, and transmits a portion of the process contact forces to the first component and / or the second component, whereby the process contact force of the stationary shoulder prevents the escape of plasticized material from the forming chamber.

[0027] The machine guiding the friction stir welding tool can be, in particular, a robot or manipulator, or a robot arm. Alternatively, the machine can also be, for example, a gantry system or a machine tool, such as a CNC machine or a machining center.

[0028] In the case of a robot, this can include a robot arm and a robot controller. The robot controller is designed and configured to adjust the joints of the robot arm automatically or manually, so that the joint angle configuration of the robot arm's joints changes, and the tool flange moves along a planned path to guide the friction stir welding tool to form a weld along the joint.

[0029] The sealed forming chamber can be formed by the standing shoulder having a closed annular end wall arranged completely around the stirring pin, which, during the automatic movement of the friction stir welding tool along the path on which the joint runs, lies flush against the surface of at least one component with a process contact force over its entire circumference, such that the escape of plasticized material is prevented.

[0030] The stationary shoulder can accordingly be formed by a shoulder body having an axial bore in which the rotating stir pin is positioned. An annular flow channel is formed between the outer wall of the stir pin and the inner wall of the shoulder body, through which the filler material is conveyed into the forming chamber. Since filler material is fed into the forming chamber completely around the stir pin via the annular flow channel, no plasticized material can escape from the forming chamber through this annular flow channel. The shoulder body has an annular end wall surrounding the stir pin, which is pressed onto a surface of the at least one component by means of the process contact force of the friction stir welding tool.The ring end wall seals the molding chamber against the component, so that no plasticized material can escape between the standing shoulder and the component.

[0031] An inner ceiling wall can be formed within the surrounding ring end wall, which limits the forming chamber at the top. In the case of a vertical shoulder with a fully circumferential ring end wall, a weld seam can be formed that is flush with the surface of at least one component.

[0032] As an alternative to a fully circumferential, closed ring end wall, the sealed forming chamber can be formed by the stationary shoulder having a ring end wall arranged around the stirring pin by less than 360 degrees, which, during the automatic movement of the friction stir welding tool along the path on which the joint runs, rests flush against the surface of the at least one component over its partial circumference with a process contact force, such that the escape of plasticized material is prevented.A groove on the standing shoulder, resulting from the less than 360-degree circumferential ring end wall and leading radially outwards from the stirring rod, forms a matrix that defines the shape of a cavity through which, during the automatic movement of the friction stir welding tool along the path on which the joint runs, plasticized material is conveyed from the forming chamber due to the independently set pressure of the additive material, in such a way that the plasticized material has already solidified before exiting the groove, thus preventing the escape of plasticized material from the forming chamber.

[0033] In this alternative embodiment, the stationary shoulder can be formed by a shoulder body with an axial bore in which the rotating stir pin is positioned. An annular flow channel is also formed between the outer wall of the stir pin and the inner wall of the shoulder body, through which the filler material is conveyed into the forming chamber. Since filler material is fed into the forming chamber completely around the stir pin via the annular flow channel, no plasticized material can escape from the forming chamber through this annular flow channel. In this case, the shoulder body has an annular end wall that does not completely encircle the stir pin. Accordingly, the open annular end wall is only pressed against a surface over a partial circumference by the process pressure of the friction stir welding tool.

[0034] The surface of at least one component is pressed down.

[0035] The ring end wall does not completely seal the forming chamber against the component. Rather, a channel remains due to the groove formed by the open ring end wall. A raised weld seam formed within the forming chamber moves out of the forming chamber through this channel when the friction stir welding tool is automatically guided along the joint on the component. The friction stir welding process must be carried out in such a way that the raised weld seam transitions from its plasticized state to a hardened state while still within the channel bounded by the groove of the standing shoulder and the surface of the component. Consequently, the groove or channel with the hardened raised weld seam within it continues to seal the forming chamber, so that even in this case no plasticized material can escape between the standing shoulder and the component. Nevertheless, a raised weld seam can still be formed.

[0036] Within the surrounding ring end wall, an inner ceiling wall can be formed, which limits the forming chamber at the top. In the case of a vertical shoulder with a ring end wall that does not completely surround the entire surface, a raised weld seam can be formed due to the groove in the vertical shoulder. The vertical shoulder terminates flush with the surface of this weld seam in the area of ​​the groove, creating a forming chamber sealed against the escape of plasticized material.

[0037] The pressure of the plasticized material in the forming chamber can be controlled and / or regulated by means of a pressure valve or flow valve that is independently adjustable from the rotational speed of the stirring rod and the delivery rate of the conveying device. The pressure valve or flow valve can, for example, be formed by a sleeve or mandrel that is axially adjustable in the base body or shoulder of the friction stir welding tool, the end face of which interacts with an annular seat surface in the base body or shoulder to create a variable annular gap. Alternatively, the gap can also be adjustable by an actuator and, for example, formed by two gap bodies that are adjustable relative to each other in a planar plane by the actuator.

[0038] In a flow channel leading from the conveying device to an outlet opening of the standing shoulder that opens into the molding chamber, the flow cross-section for the plasticized additive material can be variably designed, and by changing the flow cross-section in the flow channel, the pressure and / or the mass flow of the plasticized additive material can be controlled and / or regulated.

[0039] Despite maintaining a constant conveying capacity for the additive material, a targeted pressure reduction in the molding chamber can be achieved by changing the flow cross-section in the flow channel for the plasticized additive material. This reduction is due to the throttling effect of a constricted flow cross-section. Conversely, increasing the flow cross-section increases the pressure in the molding chamber. A pressure increase can generally be achieved by increasing the conveying capacity, for example, by increasing the rotational speed of a screw conveyor. However, without using a device that changes the flow cross-section in the flow channel, the mass flow rate into the molding chamber would also increase. To maintain a constant mass flow rate, the flow cross-section in the flow channel can be reduced accordingly.

[0040] Since, in the present invention, the additive material is conveyed into the molding chamber via a conveying device separate from the stirring pin, the pressure in the molding chamber and the amount of additive material conveyed into the molding chamber are independent of the rotational speed of the stirring pin. Consequently, the plasticizing energy introduced into the plasticizing zone by the stirring pin can be set or controlled independently of the pressure introduced into the molding chamber.

[0041] Since, in the present invention, the flow cross-section in the flow channel of the plasticized additive material can be changed during the movement of the friction stir welding tool along the joint, the pressure of the plasticized material, which can comprise plasticized material of the at least one component and the additive material, can be controlled or regulated in the forming chamber without having to change the conveying capacity of the conveying device.

[0042] The conveying capacity of the conveying system can therefore be primarily adjusted to the energy required for plasticizing the additive material. This can be done without any process-related effects on the already plasticized material in the molding chamber.

[0043] An additional material can be a material different from the material of at least one component.

[0044] Friction stir welding can be performed on the at least one first component on one side using a stationary shoulder tool. Alternatively, friction stir welding can be performed on both sides of the at least one first component using a stationary double shoulder tool. The double shoulder tool can have a rotating stir pin, which is, for example, cylindrical or double-conical, and which can be provided with grooves, slots, or spiral channels on its outer surface through which the plasticized filler material can be guided to the rear of the components. This makes it possible to adjust the pressure not only on the upper front of the components in an upper forming chamber of an upper shoulder of the double shoulder tool, but also on the upper front surface.The aim is not only to be able to control or regulate the pressure, but also to adjust, control, or regulate it on the lower back side of the components in a lower forming chamber of a lower shoulder of the double-shoulder tool. The upper and lower shoulders, or the upper and lower forming chambers, can be identical, so that an identically designed seam or weld reinforcement can be achieved on both sides of the components. Alternatively, the upper and lower shoulders, or the upper and lower forming chambers, can be designed differently, so that a differently designed seam or weld reinforcement can be achieved on one side of the components than on the opposite side. For example, a flat seam on one side of the components can be combined with a raised seam on the other side.

[0045] The problem is also solved by a friction stir welding tool, in particular for carrying out a process as described, comprising: a base body,

[0046] - a stirring stick rotatably mounted in the base body ,

[0047] - a standing shoulder arranged at least partially or completely around the stirring stick, which has an annular end wall designed for flush contact with a surface of at least one component, and

[0048] - a flow channel running in the base body for transporting a plasticized additive material supplied by a conveying device, wherein the flow channel opens into an annular outlet opening of the friction stir welding tool between the stationary shoulder and the stir stick, and an automatically adjustable pressure valve or flow valve is arranged in the flow channel.

[0049] The automatically adjustable pressure valve or flow valve can have a mandrel mounted axially adjustable within the base body, which interacts with an annular seat surface surrounding the mandrel and formed in the base body or in the standing shoulder, in order to form an annular gap that variably determines the flow cross-section of the flow channel for the plasticized additive material through its axial adjustability.

[0050] The mandrel can accordingly be arranged coaxially to the stirrer. The mandrel can be formed by a pipe section surrounding the stirrer on its outer surface, which is adjustable within the stationary shoulder of the friction stir welding tool in the axial direction with respect to the axis of rotation of the rotating stirrer. The lower end of the mandrel or pipe section can, for example, have a conical outer wall that interacts with an annular seat surface surrounding the conical outer wall by defining an annular gap whose opening cross-sectional area can be changed by axially adjusting the mandrel or pipe section. The annular seat surface can have a conical inner wall corresponding to the conical outer wall of the mandrel.

[0051] The conveying device for the additive material can also include a screw conveyor arranged coaxially to the agitator, the outer wall of which, together with an inner wall of the shoulder body, forms the flow channel for the plasticized additive material. In this case, the mandrel or pipe section can be functionally integrated with the screw conveyor. For example, the screw conveyor can be mounted not only rotatably in the shoulder body but also axially adjustable within it. The leading end of the screw conveyor, in the direction of flow of the plasticized additive material, can have the conical outer wall and thus form the mandrel. This allows the leading end of the screw conveyor to interact with the annular seat surface of the shoulder body, and the opening cross-sectional area in the flow channel can be changed by axially adjusting the screw conveyor.The axial adjustment of the screw conveyor can therefore preferably be carried out independently of the speed of the screw conveyor.

[0052] As already mentioned, the machine guiding the friction stir welding tool can be, in particular, a robot or manipulator, or a robot arm. Alternatively, the machine can also be, for example, a gantry system or a machine tool, such as a CNC machine or a machining center.

[0053] The problem is also solved by a friction stir welding device for carrying out a method according to one of the described embodiments, comprising a robot arm with several links and the links automatically adjustable joints relative to each other, wherein the joints are adjustable by electric motors which are controlled automatically by a robot controller or in a manual operation, wherein the robot arm has a tool flange to which a friction stir welding tool is attached, so that by controlling the joints of the robot arm by the robot controller the friction stir welding tool can be controlled and moved according to a method according to one of the described embodiments.

[0054] The problem is further solved by a computer program product comprising a machine-readable carrier on which program code is stored, which can be read by a machine control of a machine, in particular by a robot control of a robot which guides a friction stir welding tool, and which trains and / or sets up the machine control, in particular the robot control, to carry out a method according to one or more embodiments as described, when the program code is executed by the machine control, in particular by the robot control.

[0055] The computer program product can be, for example, a CD, a DVD, or a USB stick. It can also be a control board with integrated microprocessors. Alternatively, the computer program product can be implemented as a download that can be offered and sold via the internet or another network.

[0056] The machine-readable medium can therefore be a CD, a DVD, or a microprocessor on which the program code is stored. However, the machine-readable medium can also be a hard drive or an SSD onto which the program code has been downloaded, for example, by means of a download, especially in the form of data packets.

[0057] The program code can be represented by an edited program and / or data stored on the machine-readable medium.

[0058] By reading out the edited program and / or the data, the reading machine control or the robot control is trained and / or set up to be able to carry out the method according to the invention by controlling the machine or the robot arm in order to move the friction stir welding tool accordingly.

[0059] The method according to the invention is carried out when the machine control or the robot control actually executes the program code, i.e. the edited program, accordingly and / or actually processes the data accordingly.

[0060] Specific embodiments of the invention are explained in more detail in the following description with reference to the accompanying figures. Specific features of these exemplary embodiments can, regardless of the specific context in which they are mentioned, and optionally also individually or in further combinations, represent general features of the invention. The figures show:

[0061] Fig. 1 shows a flowchart of the steps in the basic method according to the invention.

[0062] Fig. 2 shows a schematic representation of an exemplary friction stir welding device according to the invention, comprising a robot controller, a robot arm controlled by the robot controller, and a friction stir welding tool guided by the robot arm.

[0063] Fig. 3 shows a schematic sectional view of an exemplary embodiment of a friction stir welding tool with an axially adjustable mandrel for variable determination of an annular gap of the friction stir welding tool.

[0064] Fig. 4 shows a perspective view of a first embodiment of a shoulder of the friction stir welding tool with a closed circumferential ring end wall,

[0065] Fig. 5 shows a sectional view of the first embodiment according to Fig. 4 on the component.

[0066] Fig. 6 shows a perspective view of a second embodiment of a shoulder of the friction stir welding tool with a partially circumferential ring end wall and with a groove, and

[0067] Fig. 7 shows a sectional view of the second

[0068] From the design variant according to Fig. 6 am

[0069] Component.

[0070] Figure 1 illustrates a process for producing a weld seam using a friction stir welding tool 8 with a stationary shoulder 9, automatically guided by a machine 2 along a joint 10, as a flow diagram. The process shown in Figure 1...

[0071] Reference symbols not shown can be found in Figures 2 to 5.

[0072] In a first step S 1 of the process, a stirrer 13 of the friction stir welding tool 8 is immersed into at least one component 11 with an immersion pressure force directed towards the component 11 in the direction of rotation axis R of the stirrer 13, in order to plasticize component material in a plasticizing zone in the area of ​​the joint 10 by rotating the stirrer 13 until the stationary shoulder 9 of the friction stir welding tool 8 is in contact with the component 11 , 12 .

[0073] In a second step S2 of the process, during the automatic movement of the friction stir welding tool 8 along a path on which the joint 10 runs, a process contact force of such a force is applied by the friction stir welding tool 8 to the component 11 by automatically controlling a machine 2 guiding the friction stir welding tool 8, which in the case of the present embodiment is a robot or a robot arm 2a, such that a forming chamber 18 is formed between the component 11 and the stationary shoulder 9, sealed against the escape of plasticized material.

[0074] In a third step S3 of the process, during an automatic movement of the friction stir welding tool 8 along the path on which the joint 10 runs, an additive material is fed by means of a conveying device 19 over the friction stir welding tool 8 into the sealed forming chamber 18 in a plasticized state of the additive material at a pressure that can be adjusted independently of the rotational speed of the rotating stir stick 13 and the conveying capacity of the conveying device 19.

[0075] Fig. 2 shows a friction stir welding device 1 for carrying out a method according to one of the described embodiments, comprising a robot arm 2a with several links 3 and the links 3 automatically adjustable joints 4 relative to each other, wherein the joints 4 are adjustable by electric motors 5 which are controlled automatically or manually by a robot controller 6, wherein the robot arm 2a has a tool flange 7 to which a friction stir welding tool 8 is attached, so that by controlling the joints 4 of the robot arm 2a by the robot controller 6 the friction stir welding tool 8 can be controlled and moved according to a method according to one of the described embodiments.

[0076] The friction stir welding tool 8 comprises a first drive motor 14.1, which is designed and configured to drive the stir pins 13 in a rotating manner. In the present embodiment, the friction stir welding tool 8 comprises a second drive motor 14.2, which is designed and configured to drive the conveying device 19 in a rotating manner. An automatically controllable actuating device 20 can be designed and configured to adjust a mandrel 21 in the axial direction A.

[0077] Figures 2 and 3 illustrate the stirring pin 13 in an axial position before it is immersed in the first component 11 and / or the second component 12, so that the stirring pin 13 is also visible in Figures 2 and 3. Therefore, the stationary shoulder 9 does not yet contact the first component 11 and / or the second component 12 at this stage. However, during the welding process, the stationary shoulder 9 rests flush against the first component 11 and / or the second component 12 from above.

[0078] In the embodiment shown in Figs. 2 and 3, the first component 11 and / or the second component 12 are shown in a butt joint arrangement, in which two opposing end faces of the first component 11 and the second component 12 are at least largely flush with each other in the area of ​​the joint 10. The first component 11 and the second component 12 are held in position by clamping means 16 and are placed on a clamping table 17.

[0079] Figure 3 schematically shows an exemplary embodiment of a friction stir welding tool. The joint 10, and thus the direction of movement, i.e., the feed direction V of the friction stir welding tool 8, runs perpendicular to the plane of the sheet in the view shown in Figure 3.

[0080] The friction stir welding tool 8 has a base body 22, which also includes the stationary shoulder 9. The stir pin 13 is rotatably mounted in the base body 22. The stationary shoulder 9, which has an annular end wall 23, surrounds the stir pin 13 at least partially or completely. The annular end wall 23 is designed to fit flush against a surface 24 of at least one component 11, 12. In the embodiment shown in Fig. 4, the annular end wall 23 completely surrounds the stir pin 13. In the embodiment shown in Fig. 6, the annular end wall 23 does not completely, but only partially, surround the stir pin 13 and additionally has a groove 25 so that a weld reinforcement can be formed.

[0081] According to Fig. 3, the friction stir welding tool 8 has a flow channel 26 extending in the base body 22 for transporting a plasticized filler material supplied by the conveying device 19, wherein the flow channel 26 opens into an annular outlet opening 27 of the friction stir welding tool 8 between the stationary shoulder 9 and the stir pin 13, and an automatically adjustable pressure valve 27a or flow valve 27b is arranged in the flow channel 26. The filler material is supplied to the conveying device 19 via an inlet Z, for example in the form of a wire.

[0082] In the illustrated embodiment, the automatically adjustable pressure valve 27a or flow valve 27b is formed by a mandrel 21 which is axially adjustable in direction A within the base body 22 and which interacts with an annular seat surface 28 formed in the base body 22 or in the stationary shoulder 9 and which surrounds the mandrel 21, in order to form an annular gap 29 which variably determines the flow cross-section of the flow channel 26 for the plasticized additive material by means of its axial adjustability in direction A.In the flow channel 26 leading from the conveying device 19 to an outlet opening 27 of the standing shoulder 9 which opens into the forming chamber 18, the flow cross-section is accordingly variable due to the axial adjustability of the mandrel 21 in direction A and by changing the flow cross-section of the annular gap 29 in the flow channel 26 the pressure and / or the mass flow of the plasticized additive material can be controlled and / or regulated.

[0083] Figures 4 and 5 show a first embodiment of a standing shoulder 9, in which the sealed forming chamber 18 is formed by the standing shoulder 9 having a closed annular end wall 23 arranged completely around the stirring pin 13, which, during the automatic movement of the friction stir welding tool 8 along the path on which the joint 10 runs, rests flush against the surface of the at least one component 11, 12 over its entire circumference with a process contact force, such that the escape of plasticized material is prevented.

[0084] In the embodiment shown in Figures 4 and 5, the stationary shoulder 9 is formed by a shoulder base body 9a, which has an axial bore 30 in which the rotating agitator 13 is positioned. An annular flow channel 26 is formed between the outer wall of the agitator 13 and the inner wall of the shoulder base body 9a, through which the additive material is conveyed into the molding chamber 18. Since additive material is fed into the molding chamber 18 completely around the agitator 13 via the annular flow channel 26, no plasticized material can escape from the molding chamber through this annular flow channel 26. The shoulder body 9a has the ring end wall 23 surrounding the stir pin 13, which is pressed onto the surface 24 of the at least one component 11 , 12 by means of the process contact force of the friction stir welding tool 8 .The ring end wall 23 seals the forming chamber 18 against the component 11, 12, so that no plasticized material can escape between the stationary shoulder 9 and the component 11, 12. The joint 10, and thus the direction of movement, i.e., the feed direction V of the friction stir welding tool 8, runs within the plane of the sheet in the view according to Fig. 5 and is indicated by the arrow V running from left to right.

[0085] Within the circumferential ring end wall 23, an inner ceiling wall can be formed, which limits the forming chamber 18 at the top. In the case of a vertical shoulder 9 with a fully circumferential ring end wall 23, as shown in Fig. 4, a weld seam can be formed that is flush with the surface 24 of the at least one component 11, 12.

[0086] In the embodiment according to Fig. 6 and Fig. 1 7 The sealed forming chamber 18 is formed by the fact that the stationary shoulder 9 has an annular end wall 23 arranged around the stirring pin 13 by less than 360 degrees, which, during the automatic movement of the friction stir welding tool 8 along the path on which the joint 10 runs, rests flush with the surface 24 of the at least one component 11, 12 only over its partial circumference with a process contact force such that the escape of plasticized material is prevented, and a groove 25 of the stationary shoulder 9 resulting from the annular end wall 23 extending radially outwards from the stirring pin 13 forms a matrix 31 which defines the shape of a cavity over which, during the automatic movement of the friction stir welding tool 8 along the path on which the joint 10 runs, 10 runs,Plasticized material is expelled from the forming chamber 18 due to the independently controlled pressure of the additive material, in such a way that the plasticized material has already solidified before exiting the groove 25, thus preventing any further leakage of plasticized material from the forming chamber 18. This is illustrated by Fig. 7, where the plasticized material formed into a seam, which can consist of both plasticized material from component 11, 12 and the additive material, is still plasticized in a region within the groove 25 closer to the forming chamber 18, but has already solidified in a region further away from the forming chamber 18. Accordingly, the material already solidified in the groove 25 also serves to seal the forming chamber 18 against any leakage of plasticized material to the outside.

[0087] In this alternative embodiment, the stationary shoulder can accordingly be formed by a shoulder body 9a, which has an axial bore 30 in which the rotating stirring pin 13 is positioned. An annular flow channel 26 is also formed between the outer wall of the stirring pin 13 and the inner wall of the shoulder body 9a, through which the additive material is conveyed into the molding chamber 18. Since additive material is fed into the molding chamber 18 completely around the stirring pin 13 via the annular flow channel 26, no plasticized material can escape from the molding chamber 18 through this annular flow channel 26. In this case, the shoulder body 9a has an annular end wall 23 that does not completely encircle the stirring pin 13.Accordingly, the open ring end wall 23 is pressed onto the surface 24 of the at least one component 11, 12 only over a partial circumference by means of the process contact force of the friction stir welding tool 8. The ring end wall 23 does not completely seal the forming chamber 18 against the component 11, 12; rather, a channel remains due to the groove 25 formed by the open ring end wall 23, through which a raised weld seam 32 formed within the forming chamber 18 moves out of the forming chamber 18 when the friction stir welding tool 8 is automatically guided along the joint 10 on the component 11, 12. The friction stir welding process is carried out in such a way that the raised weld seam 32 transitions from its plasticized state to a hardened state within the channel bounded by the groove 25 of the standing shoulder 9 and the surface 24 of the component 11, 12. Consequently, the groove 25 also seals.The channel with the reinforced raised weld 32 within it continues to seal off the forming chamber 18, so that even in this case no plasticized material can escape from the forming chamber 18 to the outside between the stationary shoulder 9 and the component 11, 12. Nevertheless, a reinforced weld 32 can be formed.

[0088] The joint 10 and thus the direction of movement, i.e. the feed direction V of the friction stir welding tool 8, runs in the view according to Fig. 7 within the plane of the sheet and is indicated by the arrow V running from left to right.

[0089] Within the circumferential ring end wall 23, an inner ceiling wall can be formed, which limits the forming chamber 18 at the top. In the case of a vertical shoulder 9 with a ring end wall 23 that does not completely circumferentially, the raised weld seam 32 can be formed due to the groove 25 in the vertical shoulder 9, on the surface of which the vertical shoulder 9 terminates flush in the area of ​​the groove 25 in order to create a forming chamber sealed against the escape of plasticized material.

[0090] The pressure of the plasticized material in the molding chamber 18 can be controlled and / or regulated by means of a pressure valve 27a or flow valve 27b which can be adjusted independently of the rotational speed of the rotating stirring pin 13 and the delivery rate of the conveying device 19.

Claims

32 Patent claims 1. Method for producing a weld (32) by means of a friction stir welding tool (8) with a stationary shoulder (9) along a joint (10) automatically guided by a machine (2), comprising the steps: - Immersion of a stirring pin (13) of the friction stir welding tool (8) into at least one component (11) with an immersion pressure directed towards the component (11) in the direction of rotation axis (R) of the stirring pin (13) in order to plasticize component material in a plasticization zone in the area of ​​the joint (10) by rotating the stirring pin (13) until the stationary shoulder (9) of the friction stir welding tool (8) is in contact with the component (11), - during automatic movement of the friction stir welding tool (8) along a path on which the joint (10) runs, by automatically controlling a machine (2) guiding the friction stir welding tool (8), applying such a process contact force of the friction stir welding tool (8) onto the component (11) that a forming chamber (18) sealed against the escape of plasticized material is formed between the component (11) and the stationary shoulder (9), - during an automatic movement of the friction stir welding tool (8) along the path on which 33 the joint (10) runs, supply of an additive material by means of a conveying device (19) for the additive material over the friction stir welding tool (8) into the sealed forming chamber (18) in a plasticized state of the additive material with a pressure that can be adjusted independently of the rotational speed of the rotating stir stick (13) and the conveying capacity of the conveying device (19).

2. Method according to claim 1, characterized in that the sealed forming chamber (18) is formed by the standing shoulder (9) having a closed annular end wall (23) arranged completely around the stirring pin (13), which, during the automatic movement of the friction stir welding tool (8) along the path on which the joint (10) runs, rests flush against the surface (24) of the at least one component (11) over its entire circumference with a process contact force, such that the escape of plasticized material is prevented.

3. Method according to claim 1, characterized in that the sealed forming chamber (18) is formed by the stationary shoulder (9) having an annular end wall (23) arranged around the stirring pin (13) by less than 360 degrees, which, during the automatic movement of the friction stir welding tool (8) along the path on which the joint (10) runs, rests flush against the surface (24) of the at least one component (11) over its partial circumference with a process contact force such that escape of plasticized material is prevented, and a ring end wall that rotates less than 360 degrees (23) The resulting radial groove (25) of the stationary shoulder (9) leading outwards from the stirring pin (13) forms a matrix (31) which defines the shape of a cavity through which, during the automatic movement of the friction stir welding tool (8) along the path on which the joint (10) runs, plasticized material is conveyed out of the forming chamber (18) due to the independently set pressure of the filler material, in such a way that the plasticized material has already solidified before exiting the groove (25), so that an exit of plasticized material from the forming chamber (18) is prevented.

4. Method according to one of claims 1 to 3, characterized in that the pressure of the plasticized material in the molding chamber (18) is controlled and / or regulated by means of a pressure valve (27a) or flow valve (24b) which can be adjusted independently of the rotational speed of the rotating stirring pin (13) and the delivery rate of the conveying device (19).

5. Method according to one of claims 1 to 4, characterized in that in a flow channel (26) leading from the conveying device to an outlet opening (27) of the standing shoulder (9) opening into the forming chamber (18), the flow cross-section is designed to be variable and the pressure and / or the mass flow of the plasticized additive material is controlled and / or regulated by changing the flow cross-section in the flow channel (26).

6. Method according to one of claims 1 to 5, characterized in that the additive material is a material different from the material of the at least one component (11, 12).

7. Method according to one of claims 1 to 6, characterized in that the friction stir welding on the at least one first component (11) is carried out on one side with a stationary shoulder tool (9).

8. Method according to one of claims 1 to 6, characterized in that the friction stir welding on the at least one first component (11) is carried out on both sides with a stationary double-shoulder tool.

9. Friction stir welding tool comprising: - a basic body (22) , - a stirring stick ( 13 ) rotatably mounted in the base body (22 ), - a standing shoulder (9) arranged at least partially or completely around the stirring pin (13), which has an annular end wall (23) designed to fit flush against a surface (24) of at least one component (11, 12), and - a flow channel (26) extending in the base body (22) for transporting a plasticized additive material supplied by a conveying device (19), wherein the flow channel (26) leads into an annular outlet opening (27) of the friction stir welding tool (8) between the stationary shoulder (9) and the 36 Stirring pin (13) opens, and an automatically adjustable pressure valve (27a) or flow valve (27b) is arranged in the flow channel (26).

10. Friction stir welding tool according to claim 9, characterized in that the automatically adjustable pressure valve (27a) or flow valve (27b) has a mandrel (21) axially adjustable within the base body (22), which interacts with an annular seat surface (28) forming around the mandrel (21) in the base body (22) or in the stationary shoulder (9) in order to form an annular gap (29) which variably determines the flow cross-section of the flow channel (26) for the plasticized filler material by means of its axial adjustability.

11. Friction stir welding device for carrying out a method according to one of claims 1 to 8, comprising a robot arm (2a) with several links (3) and the links (3) automatically adjustable joints (4) relative to one another, wherein the joints (4) are adjustable by electric motors (5) which are controlled automatically or manually by a robot controller (6), wherein the robot arm (2a) has a tool flange (7) to which a friction stir welding tool (8), in particular a friction stir welding tool (8) according to claim 9 or 10, is attached, so that by The joints (4) of the robot arm (2a) can be controlled by the robot control (6) so that the friction stir welding tool (8) can be controlled and moved according to a method according to one of claims 1 to 8. 37 12. Computer program product comprising a machine-readable carrier on which program code is stored, which is readable by a machine control of a machine (2), in particular by a robot control (6) of a robot arm (2a) which carries a friction stir welding tool (8), in particular a friction stir welding tool (8) according to one of claims 9 to 11, and which forms and / or configures the machine control, in particular the robot control (6), to carry out a method according to one of claims 1 to 8 when the program code is executed by the machine control, in particular by the robot control (6).

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