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EP-4741092-A1 - METHOD FOR CONTROLLING THE CONDITION OF A STUD HOLDER OF A WELDING DEVICE AND ARRANGEMENT COMPRISING A WELDING DEVICE AND A TESTING UNIT

EP4741092A1EP 4741092 A1EP4741092 A1EP 4741092A1EP-4741092-A1

Abstract

Arrangement and method for controlling the condition of a stud holder (14) of a welding device (10) comprising the step of: - Providing a welding device comprising a stud holder extending along a longitudinal axis (X) and forming a recess adapted to receive a stud for its welding to a workpiece and a linear drive adapted to drive the stud holder for the welding of a stud to a workpiece; - Providing a testing unit; - Aligning the welding device and the testing unit (12); - Driving the stud holder (14) of the welding device toward the testing unit; - Measuring a parameter of the linear drive for assessing the condition of the stud holder.

Inventors

  • Lauer, André
  • Nab, Nicolas
  • SPIESS, Manuel
  • BRIEL, KARL-HEINZ
  • SCHNEIDER, PETER
  • EISENBERG, Christoph
  • GIERELT, Elisabeth

Assignees

  • Newfrey LLC

Dates

Publication Date
20260513
Application Date
20241111

Claims (14)

  1. Method for controlling the condition of a stud holder (14) of a welding device (10) comprising the step of: - Providing a welding device (10) comprising a stud holder extending along a longitudinal axis (X) and forming a recess adapted to receive a stud for its welding to a workpiece and a linear drive adapted to drive the stud holder for the welding of a stud to a workpiece; - Providing a testing unit (12); - Aligning the welding device (10) and the testing unit (12); - Driving the stud holder (14) toward the testing unit (12); - Measuring a parameter of the linear drive (16) for assessing the condition of the stud holder (14).
  2. Method according to claim 1, wherein the testing unit (12) comprises a base body (32) and a testing tool (34) protruding from the base body, and wherein the testing tool has a conical shape configured to be partly inserted within the recess of the stud holder.
  3. Method according to claim 2, wherein the testing tool (34) is floatingly mounted on the base body (32).
  4. Method according to any of claims 2 or 3, wherein the stud holder (14) is first driven in a base position, in which the stud holder contacts the testing tool (34) and is then further driven toward the base body (32) to measure the parameter of the linear drive for assessing the condition of the stud holder.
  5. Method according to any of claims 1 to 4, wherein the measurement is realized by controlling the movement of the linear drive (16) up to a defined position and comparing the measured force used by the linear drive to reach the defined position with a reference force.
  6. Method according to any of claims 1 to 4, wherein the measurement is realized by moving the linear drive (16) until a pre-defined force is reached and comparing the position reached with a reference position.
  7. Method according to any of claims 1 to 4, wherein the measurement is realized by moving the linear drive (16) up to a reference position, recording the force-displacement curve, and comparing the recorded force-displacement curve with a reference force-displacement curve.
  8. Method according to any of claims 5 to 7, wherein an alert for programming the replacement of the stud holder (14) is sent to a control unit if: - the measured counterforce is outside of the reference force range, or - the reached position is outside of the reference position range, or - the recorded force-displacement curve is outside of the reference force-displacement curve range.
  9. Method according to any of claims 1 to 8, wherein the steps of: - Aligning the welding device (10) and the testing unit (12); - Driving the stud holder (14) toward the testing unit (12); - Measuring a parameter of the linear drive for assessing the condition of the stud holder, are undertaken at pre-programmed time or usage intervals.
  10. Method according to any of claims 1 to 9, wherein a machine learning system (38) is associated with the welding device (10) for analyzing and predicting the replacement of the stud holder based on the measured parameter of the linear drive.
  11. Method according to any of claims 1 to 10, wherein a robot arm moves the welding device (10) for its alignment with the testing unit.
  12. Method according to any of claims 1 to 10, wherein the welding device (10) is manually aligned with the testing unit (12).
  13. Arrangement for implementing the method according to any of claims 1 to 12, comprising a welding device (10) with a stud holder (14) and a linear drive (16) integrated to the welding device adapted to move the stud holder for the welding of a stud to a workpiece, and a testing unit (12) comprising a base body and a testing tool protruding from the base body, wherein the testing tool has a conical shape.
  14. Arrangement according to claim 13, wherein the stud holder (14) comprises a plurality of tongues distributed around the longitudinal axis (X), wherein the plurality of tongues is adapted to be arranged at least partly around the testing tool and to contact said testing tool.

Description

The present invention is directed to a method for controlling the condition of a stud holder. More particularly, the present invention is directed to a method for controlling the operational status or the remaining life time of a stud holder in a stud welding device. The present invention is further directed to an arrangement for implementing the method for controlling a stud holder, in particular a stud holder of a stud welding device. Stud welding is often performed as an automated process and a plurality of welds are performed by the same device. The positioning of the welding head or the bolt and the welding are implemented automatically. Stud welding devices commonly comprise a welding head with a stud holder having a pointed region for holding a weld stud. The stud holder is movable substantially perpendicularly to the surface of a workpiece and away from it by a linear drive. The linear drive is provided or cooperate with a sensor unit adapted to detect the force or the displacement or both. The welding device comprises a system for producing an arc by lifting and striking between the weld part and the surface of the workpiece. For example, GB2094201 discloses an electrical stud welding apparatus adapted to weld studs of different diameters with a conical feeler used to determine the diameter of the bore of the stud holder. The stud holder may be a hollow tubular stud holder which is tapered in its pointed region and has tongues which are formed in such a way that a weld stud pushed through the hollow tubular stud holder spreads the tongues apart upon its arrival in the pointed region and can therefore be pushed out of the stud holder completely. A weld stud pushed through the stud holder is pushed out of the stud holder to a certain extent, so it can be welded to a component or a workpiece. Once the weld stud has been welded to the component the entire stud welding device is pulled back along the weld stud axis and the stud holder releases the weld stud completely. The quality of the welding result depends, inter alia, on the fact that the studs are accurately positioned and are welded essentially perpendicular to the component. If damages occur to the stud holder, the stud is no longer held properly and can, for example, be obliquely-welded to a component or workpiece. Document DE20105789U1 discloses a stud holder provided with a sensor equipment, for example strain gauges, adapted to detect a broken tongue of the stud holder. Document US5048320 is more generally directed to a method of inspection of structures with a pressure sensor. Document DE10035371 also discloses a stud holder comprising a sensor equipment connected to an evaluation and control unit in order to compare a nominal value with a measured value. Such processing allows to detect a stud holder which is defect. However, such sensor equipment is difficult to implement, raises the costs of a stud holder and require space. Indeed, the assembly of the sensor equipment on the stud holder is necessary and if a stud holder has to be changed, the sensor equipment has to be removed from the old stud holder and mounted to the new stud holder. This step is time-consuming and difficult to implement in an industrial environment. DE102014212735A1 is directed to a method for welding stud, in which an optical control of the stud holder is performed by means of an optical control device. The stud holder is moved from a welding position into a checking position for carrying out the optical control. An evaluation unit processes the image data of the stud holder and evaluates it with regard to the presence of a fault. Such method implies an image comparison. The processor will detect or not the presence of a faulty stud holder. The faulty stud holder is then changed. However, such optical control does not allow an early detection of a faulty stud holder. Besides, the optical control can only be used in a very clean environment, in order to avoid any image disturbance. Document EP3473369B1 discloses a method of controlling the remaining life time of a stud holder having a testing device comprising a testing tool and a sensor adapted to measure a testing force of the testing tool. Such method is satisfactory, however there is still a need to provide an improved method that is easy to implement in any environment and that limits the number of additional components. Examples of the present disclosure aim to address the aforementioned problems. According to an aspect of the present disclosure there is a method for controlling the condition of a stud holder of a welding device comprising the step of: Providing a welding device comprising a stud holder extending along a longitudinal axis and defining a recess adapted to receive a stud for its welding to a workpiece, and a linear drive adapted to drive the stud holder for the welding of a stud to a workpiece; Providing a testing unit;Aligning the welding device and the testing unit;Driving the stud holder towar