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DE-102024132640-A1 - 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

DE102024132640A1DE 102024132640 A1DE102024132640 A1DE 102024132640A1DE-102024132640-A1

Abstract

The invention relates to a method for producing a weld (32) using a friction stir welding tool (8) with a stationary shoulder (9) automatically guided by a machine (2) along a joint (10), including the step of feeding filler material by means of a conveying device (19) over the friction stir welding tool (8) into a sealed forming chamber (18) in a plasticized state of the filler material at a pressure that is independently adjustable from the rotational speed of a rotating stir pin (13) and the conveying capacity of the conveying device (19). The invention also relates to a friction stir welding tool (8), an associated friction stir welding device (1), and a corresponding computer program.

Inventors

  • Stefan Fröhlke
  • Bernd Richter

Assignees

  • KUKA DEUTSCHLAND GMBH

Dates

Publication Date
20260513
Application Date
20241108

Claims (12)

  1. A method for producing a weld seam (32) using a friction stir welding tool (8) with a stationary shoulder (9) automatically guided by a machine (2) along a joint (10), comprising the steps of: - Immersing a stir 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 rotational axis (R) direction of the stir pin (13) in order to plasticize component material in a plasticization zone in the area of the joint (10) by rotating the stir 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) on the component (11) such 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 the joint (10) runs, a filler material is fed by means of a conveying device (19) for the filler material over the friction stir welding tool (8) into the sealed forming chamber (18) in a plasticized state of the filler material with a pressure that is independently adjustable from the speed of the rotating stir pin (13) and the conveying capacity of the conveying device (19).
  2. Procedure 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. Procedure 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 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 die (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) plasticized material is conveyed out of the forming chamber (18) 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 (25), so that the escape of plasticized material from the forming chamber (18) is prevented.
  4. Procedure according to one of the Claims 1 until 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. Procedure according to one of the Claims 1 until 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 variably designed 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. Procedure according to one of the Claims 1 until 5 , characterized in that a material different from the material of the at least one component (11, 12) is used as the additional material.
  7. Procedure according to one of the Claims 1 until 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. Procedure according to one of the Claims 1 until 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 base body (22), - a stirring pin (13) rotatably mounted in the base body (22), - a standing shoulder (9) arranged at least partially or completely circumferentially 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) opens into an annular outlet opening (27) of the friction stir welding tool (8) between the standing shoulder (9) and the stirring pin (13), and an automatically adjustable pressure valve (27a) or flow valve (27b) is arranged in the flow channel (26).
  10. Friction stir welding tool after 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 additive material by means of its axial adjustability.
  11. Friction stir welding device for carrying out a process according to one of the Claims 1 until 8 , 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) on 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 controlling the joints (4) of the robot arm (2a) by the robot controller (6) the friction stir welding tool (8) is moved according to a method according to one of the Claims 1 until 8 can be controlled and moved.
  12. Computer program product comprising a machine-readable carrier on which program code is stored, which is controlled by a machine controller of a machine (2), in particular by a robot controller (6) of a robot arm (2a), which controls a friction stir welding tool (8), in particular a friction stir welding tool (8) according to one of the Claims 9 until 11 leads, is readable and trains and/or sets up the machine control, in particular the robot control (6), a method according to one of the Claims 1 until 8 to be carried out when the program code is executed by the machine control, in particular by the robot control (6).

Description

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. The process for producing a weld using a machine-guided friction stir welding tool with a stationary shoulder 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 known as FSW welding (English: Friction Stir Welding). In a basic application, two separate components, for example in a butt joint, are joined with two opposing end faces and held in position by means of a clamping device. A friction stir welding tool comprises a stirring pin that rotates during the welding process and a 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. The shoulder can either rotate with the stirring pin or be a stationary shoulder that does not rotate with it. Stationary shoulder friction stir welding is also known as SSFSW welding (English: Stationary Shoulder Friction Stir Welding). In the first process step, the stirring pin 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. Friction effects generate heat in the contact area between the rotating stirring pin and the component, causing the at least one component to plastically degrade in the area of the rotating stirring pin. Due to this plasticization, the rotating stirring pin can penetrate deeper into the component. Subsequently, the rotating stirring pin is moved along the joint 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 by cooling in the direction of movement behind the rotating stirring pin, forming the finished weld. Finally, at the end of the weld seam or further away from the fully produced weld seam, the rotating stirring pin is pulled out of the still plasticized zone on the stirring pin and out of the welded components. The DE 10 2014 115 535 B3 This document describes a friction stir welding tool comprising a non-rotating shoulder, which has a first workpiece contact surface for contacting a workpiece to be welded, and at least one rotating pin. 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. The friction stir welding tool also has a material feed opening located away from the first workpiece contact surface and opening into the gap. Furthermore, the document describes an associated friction stir welding method in which 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. The additional material is transported by the axially acting screw conveyor and 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 could negatively impact the process conditions in the pin's plasticizing zone. Consequently, it has been proposed to operate the pin's rotation and the rotation of a separate extruder screw for transporting and plasticizing the additional material independently. The DE 10 2022 112 431 B3 Describes a device for friction stir welding of workpieces with the supply of 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 abutment. With this design, the conveying capacity of the extruder and the plasticiz