Field of the invention

The present invention relates to a welding wire dispenser, a system for providing welding wire, a method for dispensing welding wire and a method for providing a welding robot with a welding wire dispenser.

Background of the invention

Industrial welding may involve large quantities of welding wire. Such welding wire is supplied on a welding wire enclosure, usually a stack of coiled wire provided in a wire drum. Wire from the welding wire enclosure is then fed to a welding station, for example a welding robot.

Steel welding wires are usually applied to or arranged in the welding wire enclosure pre-tensioned with torsion, in such a way that twist in the wire after unrolling can be minimised. These wires are usually designated as 'twist-free'. However, not all wire materials can be applied to a welding wire enclosure this way, for example due to creep or a relatively low yielding strength.

Further, as a result of e.g. fluctuations in the supply rate of the wire and variations in the condition of the wire and/or the welding wire enclosure, it is not always possible to completely prevent the occurrence of twist in the wire.

When pulling the welding wire from the welding wire enclosure, especially in case of welding wires that are prone to twisting, such as relatively thin wielding wires, and/or in case of wire dispensed from wire drums, residual stresses may be introduced and/or aggravated in the welding wire. As a result, the welding wire could deform plastically during dispensing and/or the output direction of the welding wire out of the welding torch may vary slightly, which may lead to uneven torch wear, arc wander and, as a result, potentially unpredictable welding results.

As a result, it is has become apparent that it is relatively difficult to obtain a relatively straight welding wire after uncoiling the welding wire, especially in the case of welding wires prone to twist, for example in welding wires comprising aluminium, tin, zinc or alloys thereof.

Wire straighteners comprising rollers may therefore be applied to straighten the wire to reduce deformations and/or residual stresses in the welding wire before the welding wire is supplied to the welding torch. However, rollers require calibration and precise adjustment to set the level of straightening. Further, it has been found that too little straightening may yield insufficient effects, and that too much straightening may reduce the quality of the welding wire, as surface deformation on the welding wire, such as scratches, could influence the weld quality. Therefore, finding the right amount of straightening further complicates the welding process.

Additionally, straightening rollers introduce friction which can cause wear and heat and potentially affects the welding wire. The friction force needs to be compensated for by a welding wire feed mechanism, such that a stronger and or additional welding wire supply mechanism is necessary which increases energy consumption and operational costs of the welding station.

Object of the invention

It is therefore an object of the invention to provide a welding wire dispenser that overcomes one or more of the disadvantages of the prior art, or at least to provide an alternative welding wire dispenser, for example a welding wire dispenser that dispenses a relatively straight welding wire, a welding wire dispenser that requires less or none straightening of the welding wire and/or a welding wire dispenser that yields better welding results at lower operational costs.

Summary of the invention

The present invention provides a welding wire dispenser for supplying welding wire from a welding wire enclosure, such as supplying a welding wire from a welding wire stack in a wire drum, according to claim 1. The welding wire dispenser comprises a turntable for supporting the welding wire enclosure, having a motor for rotating the welding wire enclosure around a rotation axis with a rotation speed to dispense welding wire and a controller to control the rotation speed; a wire guide associated with the turntable for guiding the welding wire out of the welding wire enclosure from a pickup direction transverse to the rotation axis in a guiding direction having a component in the direction of the rotation axis; and a sensor connected to the controller for measuring a movement signal representative for movement of the wire guide. The controller is configured to adjust the rotation speed in dependence of the measured movement signal.

By adjusting the rotation speed of the turntable in dependence of the measured movement signal, the tension in the welding wire may be influenced, for example in the rotation direction, such that the chances of introduction and aggravation of deformation and/or residual stresses in the welding wire can be reduced.

In particular, the rotation speed may be adjusted such that the welding wire is removed from the coiled welding wire stack in a relatively constant pickup direction, for example in a pickup direction having a relatively constant angle with respect to the coiled welding wire stack. Due to the advantageous combination of guiding the welding wire in a direction transverse to the rotation axis and adjustment of the rotation speed of the turntable, the welding wire dispenser may significantly reduce the chances on deformation and/or residual stresses in the welding wire.

As the rotation axis is perpendicular to the plane of rotation of the turntable, tension and/or deformation of the welding wire may be reduced in three orthogonal dimensions. Advantageously, upon uncoiling from the coiled welding wire stack with the welding wire dispenser, the welding wire may be relatively straight, for example completely straight.

The welding wire may be dispensed such that the chances of twist in the wire are effectively reduced. In particular, the chances of twist may be reduced to such an extent that wire straighteners are not necessary any more for straightening of the wire before being supplied to the welding torch.

As such, a welding wire may be obtained that can be supplied to a welding torch without prior rolling, whereby uneven torch wear and arc wander are potentially reduced or prevented. Damage of the surface of the welding wire due to rolling may be avoided, such that a welding wire, for example aluminium with a smooth surface and/or a consistent properties may be dispensed. Thereby, predictable welding results having a good weld quality may be obtained at a lower energy consumption and lower operational costs than with existing techniques.

The welding wire enclosure may be a closed wire container, such as a wire drum. Wire drums are usually have a circular or rectangular cross section and have a cylindrical shape but may also be provided with other shapes. The wire drum may typically have a diameter of 0,52 - 0,75 m and a height of 0,39 - 1 ,1 m, such as a PAK52, PAK65, Jumbo or PAK75 wire drum, but may also be provided with different dimensions.

The welding wire enclosure may be a stationary welding wire enclosure, that is, a welding wire enclosure that is normally positioned stationary on the ground. In particular, a stationary welding wire enclosure may be allow welding wire to be drawn therefrom without movement of the welding wire enclosure. It has surprisingly been found that better welding results may be achieved by rotating the normally stationary welding wire enclosure on a turntable.

The welding wire dispenser has been found to be relatively effective in reducing the chances of twist of welding wires, in particular in aluminium welding wires from wire drums.

The welding wire may be stacked in the welding wire enclosure, in particular, the welding wire may be stacked in coils, defining a hollow interior space surrounded by the welding wire stack. The turntable may include a support surface for placing a welding wire enclosure, such as a wire drum. The support surface may have supports for supporting the welding wire enclosure. The welding wire enclosure may be supported such that it rotates with the rotational speed of the turntable. The support surface may be arranged to receive a wire drum, such as a circular or multi-angular wire drum. In particular, the turntable may comprise a flat surface.

The wire guide is designed to guide the welding wire. In particular, the wire guide may be configured to guide the welding wire from a wire drum rotating on the turntable in a guiding direction. The guiding direction may be a stationary direction, which is for example determined by further guides that lead the welding wire to a welding station.

The wire guide may be rotatable around an axis substantially parallel to the rotation axis of the turntable and the wire guide may be configured to be rotated around that axis by the welding wire when welding wire is supplied.

The wire guide may be movable in a least a direction parallel to the axis of rotation. This way, the wire guide may follow movement of the welding wire parallel to the rotation axis. As such, the wire guide may move according to a decreasing size of the coiled welding wire stack. In particular, in case of a vertical coiled welding wire stack, the wire guide may move downward with a decreasing height of the coiled welding wire stack due to use of welding wire

Therewith, tension in the welding wire parallel to the rotation axis may be reduced. In this embodiment, the combination of movement of the wire guide in a direction parallel to the rotation axis and adjustment of the rotation speed of the turntable, the chances on deformation and/or residual stresses in the welding wire may be further reduced.

The wire guide may be configured to be positioned at least partially in the welding wire enclosure for guiding the welding wire out of the enclosure. This way, the chances of plastic deformation of the welding wire may be further reduced. For example, the wire guide may be shaped to at least partially fit in the enclosure, e.g. having a width less than inner diameter of the enclosure. In particular, the wire guide may be configured to be positioned at least partially in or above a hollow interior space surrounded by the welding wire stack.

The pickup direction may be determined by an detachment point of the welding wire on the welding wire stack, stiffness of the welding wire, tension in the welding wire and/or a welding wire dispensing rate. Due to uncoiling of the welding wire, the detachment point of the welding wire may move around the welding wire stack, for example around the inner circumference thereof. The wire guide may be rotatable around the axis of rotation. This way, the pickup direction may be variable. For example, the pickup direction may follow movement of the detachment point.

The sensor may be configured to measure a movement signal directly by measuring movement of the welding wire and/or the wire guide. Alternatively, the sensor may measure a movement signal indirectly by measuring other properties of the welding wire, such as a tension in the wire, e.g. via a load cell connected to the wire guide or further wire guide, or by optically determining curvature of the wire, e.g. via a camera.

In an embodiment, the controller is configured to adjust the rotation speed of the turntable with respect to the wire guide, for example a mounting point or bearing thereof, to keep the movement of the wire guide below and/or around a predefined threshold value. By adjusting the rotation speed, welding wire may be uncoiled slower and/or faster from a welding wire stack to influence movement of the wire guide, and therewith, wire tension.

In an embodiment, the controller is configured to adjust the rotation speed of the turntable to keep the wire tension below and/or around a predefined threshold value, for example to keep the wire tension below a yield strength of the welding wire.

The controller may be configured to adjust the rotation speed by activating or deactivating the turntable, and/or to adjust the rotations speed by varying the rotation speed when the turntable is active.

In particular, the rotation speed may be adjusted such that the pickup direction has a relatively constant angle with respect to the coiled welding wire stack.

The controller may for example be configured to increase the rotation speed when the movement signal represents a relatively high wire tension, for example when the wire tension, the movement of the wire guide, e.g. position or the velocity thereof, exceeds the threshold value, and to decrease the rotation speed when the movement signal represents a relatively low wire tension, for example when the wire tension and/or the movement of the wire guide, e.g. a position or opposite velocity, falls below a threshold value. Also multiple threshold values and/or more advanced control configurations may be used. The controller may for example comprise P, PI or PID control, linear-quadratic regulation, model-predictive control, or other types of control.

In an embodiment, the sensor is arranged to measure movements of the wire guide that are representative for tension in the welding wire. The wire guide may be moved by forces of the wire acting on the wire guide, such as the wire tension.

In particular, at a certain wire tension, the pickup direction may have a predetermined relation with an detachment point of the welding wire on the welding wire stack, depending on stiffness of the welding wire and production method of the coiled welding wire stack, such that movement of the wire guide is representative for an increase or decrease in wire tension.

The controller may be configured to adjust the rotation speed of the turntable to keep the wire guide relatively stationary. In particular, the detachment point on the welding wire stack may be held in a stationary position with respect to the surroundings.

In an embodiment, the wire guide is rotatable around the rotation axis. This way, the wire guide may have a constant distance to the turntable and/or to a welding wire enclosure arranged thereon, which is advantageous as that distance differences could influence the measured movement signal.

In a further embodiment, the sensor is arranged to measure rotation of the wire guide around the rotation axis. Rotation of the wire guide around the rotation axis may be advantageous for measuring the movement signal as, even when the wire guide is moving, the rotation axis may remain stationary, such that the rotation axis may be used as reference for the sensor.

In a further embodiment, the sensor is arranged to measure a circumferential position of the guide element around the rotation axis. The circumferential position may determine the pickup direction of the wire guide. The circumferential position may be determined an angle of the guide element around the rotation axis as seen in a cross sectional view perpendicular to the rotation axis.

In an embodiment, the controller is configured to determine a difference between the measured circumferential position of the guide element and a setpoint value, and to adjust the rotation speed in dependence of the determined difference.

The sensor may be configured to measure the position but additionally or alternatively, the sensor may be configured measure a velocity, acceleration or jerk of the guide element.

The controller may be configured to determine a respective difference in velocity, acceleration, jerk, etc.

The turntable may comprise a stationary part that is stationary with respect to the surroundings, wherein the sensor is arranged to measure rotation of the wire guide with respect to the stationary part. This way, a stationary reference may be provided for the sensor to improve measurement accuracy.

In an embodiment, the wire guide is configured to follow the top layer of welding wire in a direction parallel to the rotation axis. As such, the wire guide may follow a level of the welding wire stack, such that tension of the welding wire in the direction of the rotation axis may be reduced. In an embodiment, the welding wire dispenser comprises a support element that is associated with the turntable and movable in the direction parallel to the rotation axis. The wire guide, for example an upper end of the wire guide, is rotatably mounted on the support element to be rotatable with respect to the turntable. As such, the sensor may be configured to measure rotation of the wire guide with respect to the support element.

The support element may be configured to be positioned on or in the welding wire enclosure. In particular, the support element may comprise a positioning surface to be positioned against the welding wire enclosure and/or welding wire. The positioning surface may be adapted to be positioned in a wire drum, for example on top of a welding wire stack. The wire guide may be suitable to be positioned entirely in the welding wire enclosure when the support element is arranged on top of the welding wire stack.

In particular, the wire guide may have a predefined distance with respect to the support element, such that the wire guide is positioned at least partially above a hollow interior space surrounded by the welding wire stack when the support element is on top of the welding wire stack.

The wire guide may comprise an inlet provided with an inlet guide section and an outlet provided with an outlet guide section. The inlet guide section may guide the wire guide in the pickup direction, and the outlet guide section may guide the wire guide in the guiding direction such that the wire guide is guided from a pickup direction towards the guiding direction. The wire guide may extend in the guiding direction and/or in the pickup direction. The inlet guide section may extend in a horizontal direction. In use, the pickup direction may extend in a horizontal direction, for example be substantially horizontal. The longitudinal axis of the inlet guide section may determine the pickup direction and the longitudinal axis of the outlet guide section may determine the guiding direction.

The wire guide may be curved, for example between the inlet guide section and the outlet guide section.

The wire guide may be arranged above the turn table. For example, the turn table may comprise a center and the wire guide may be arranged above the center. The center may coincide with the rotation axis. The wire guide may be arranged on the rotation axis.

The wire guide may be mounted centrally on the support element to be rotatable around the rotation axis.

The support element may be a floating support element. The floating support element may be configured to be floating, i.e. be supported by a welding wire stack, for example via the positioning surface, such that the support element floats on the welding wire stock and follows a level thereof. In a further embodiment, the sensor is arranged to measure rotation of the wire guide with respect to the surroundings. Due to rotation of the welding wire enclosure, the wire guide may be held in stationary position while being provided on a moving support element.

In an embodiment, the support element comprises a positioning surface to be positioned on a stacked welding wire in the welding wire enclosure, such that the guide element remains supported on top of the wire stack in the welding wire enclosure when the height of the welding wire stack decreases as welding wire is supplied.

In an embodiment, the support element is configured to align the guide element with respect to the rotation axis in the welding wire enclosure. The support element may be provided with alignment elements, such as surfaces, wheels or cams. The alignment elements may be configured to engage with an inner side of the welding wire enclosure for alignment. Additionally or alternatively, a diameter of the support element may be slightly less than a diameter of the welding wire enclosure for alignment, for example slightly less than 0,52—0,75 m.

In an embodiment, the wire guide, from the outlet towards the inlet, extends from the support element along the rotation axis and bends sideways away from the rotation axis. This way, the guide element may be positioned towards the outer walls of a curved welding wire stack.

The sensor may be movable with the wire guide. This way, the sensor may measure relatively close to the wire guide such that measurements are precise. In an embodiment, wherein the wire guide is movable in a direction perpendicular to the rotation axis, the sensor is movably arranged on the welding wire dispenser to move with the wire guide perpendicular to the rotation axis.

In an embodiment, the sensor is attached to the wire guide. This way, movement of the wire guide may be measured accurately.

The sensor may comprise at least one of a three-axis accelerometer, a three-axis magnetometer and/or a three-axis gyroscope, wherein the movement signal comprises one or more of an accelerometer signal, a magnetometer signal and/or a gyroscope signal.

The three-axis accelerometer may be configured to provide the accelerometer signal that is representative for an acceleration level of the sensor in at least one direction;

The three-axis magnetometer, may be configured to provide a magnetic orientation signal that is representative for an absolute position of the sensor in at least one direction e.g., with respect to the earth magnetic field.

The three-axis gyroscope may be configured to provide an angular velocity signal that is representative for an angular velocity of the sensor in at least one direction. The measured movement signal may represent combined positions, velocities, respectively accelerations in one or more orthogonal directions.

In an embodiment, the wire guide comprises a measurement surface provided with at least one marker, wherein the sensor is configured to measure the movement signal by detecting the at least one marker.

The measurement surface may be arranged such that detection of the at least one marker represents rotation of the wire guide. The measurement surface may be arranged on the outer surface of the wire guide.

Multiple markers may be provided, for example circumferentially arranged around the rotation axis, at an equal distance therefrom.

The measurement surface may for example be arranged parallel or transverse to the rotation axis, and the sensor may be arranged perpendicular to the measurement surface.

The sensor may be a proximity sensor, such as a capacitive, inductive, magnetic, optic, sound or hall effect sensor.

In an embodiment, the sensor is an optical sensor arranged to optically measure movements of the wire guide. An advantage of an optical sensor may be reliability and limited sensitivity to magnetic fields.

Further, the optical sensor may allow measurement of a wire guide at a varying distance. This way, the optical sensor may for example be provided at a fixed height, and movement of the wire guide may still be measured by the sensor as the wire guide moves downward with a depleting welding wire stack. The optical sensor may be a laser sensor.

The optical sensor may be configured to measure movements of the wire guide at a distance of a wire guide, for example at a distance approximately equal to the height of a welding wire enclosure, such as a wire drum.

The optical sensor may be arranged at a height of at least a wire drum above the turntable, such as at least 0,39 m above the turntable, for example at 0,39-1,1 m. This way, a wire drum may be provided between the turntable and the optical sensor conveniently.

Further, by having a sensor arranged at a distance from the welding wire enclosure, the chances of interference between the welding wire and the sensor, sensor wiring and/or other electronics may be reduced.

The optical sensor may comprise a light source and be configured to capture light from the light source that is reflected by the wire guide. Additionally or alternatively, the sensor may comprise a camera and be configured to measure movement of the wire guide using computer vision. In an embodiment comprising a measurement surface provided with at least one marker, the at least one marker is a reflector and the sensor is configured to measure the movement signal by detecting light reflected by the reflector.

The reflector may be arranged such that it rotates with the wire guide along the rotation axis.

In an embodiment, the sensor is configured to communicate wirelessly, for example with the controller and/or the motor. By having wireless communication, the chances of interference between the welding wire and the sensor, sensor wiring and/or other electronics may be further reduced.

The sensor may be provided with a battery. This way, the sensor may not require wiring for energy supply. The sensor may be provided with a generator or solar cell for charging the battery.

In an embodiment, the welding wire dispenser comprises a second sensor operatively connected to the controller for measuring a second movement signal representative for movement of the wire guide.

This way, redundancy may be provided. Further, by selecting a distance between a first sensor and the second sensor, a measurement precision may be determined.

Additionally, multiple sensors may be provided, for example a third and a fourth sensor.

For example, multiple sensors may be provided arranged at a distance from each other, wherein detection of the wire guide by one of the multiple sensors is representative for a respective position of the wire guide.

In an embodiment, the wire guide defines a wire path from the pickup direction towards the guiding direction, wherein the guiding direction is aligned with the rotation axis. The pickup direction may be a direction tangential to the rotation of the turntable.

In an embodiment the wire guide comprises a hollow tube. The tube may be curved, for example between the pickup direction and the guiding direction. The tubemay extend between an inlet defining the pickup direction and an outlet defining the guiding direction. A hollow tube may be advantageous to protect the welding wire from the rotating welding wire stack. A curved shape allows for a gradual turn of the welding wire to reduce the chances on plastic deformation. In an embodiment, the rotation axis is vertical. As such, the welding wire dispenser may be particularly suited for dispensing welding wire from a vertical coiled welding wire stack.

The invention further provides a system for providing welding wire: comprising a welding wire dispenser according to any of the embodiments; and a welding wire enclosure provided with welding wire, for example a wire drum provided with a welding wire stack. The system may provide benefits similar to those described hereinabove, and may particularly be useful for dispensing aluminium welding wire from a wire drum.

The welding wire may be stacked in the wire drum. Wire drums are usually placed stationary on the ground. By rotating the drum with the turntable according to the movement signal, it is now possible to disperse different types of welding wires, whereby the risk of wire twist may at least partially be reduced.

In an embodiment, the welding wire comprises aluminium, tin or zinc. These materials have been particularly susceptible to twist in the welding wire.

The invention further provides a method for dispensing welding wire, comprising the steps of providing a welding wire enclosure, for example a wire drum, on a turntable having a motor; rotating the welding wire enclosure around a rotation axis with a rotation speed to dispense welding wire from the welding wire enclosure, wherein the welding wire is guided from a pickup direction transverse to the rotation axis in a guiding direction having a component in the direction of the rotation axis; measuring a movement signal representative for movement of the wire guide; and adjusting the rotation speed of the turntable in dependence of the measured movement signal.

The method may provide benefits similar to the benefits of embodiments of the welding wire dispenser described hereinabove.

In an embodiment, the method comprises the step of adjusting the rotation speed of the turntable with respect to the wire guide to keep the wire tension below and/or around a predefined threshold value.

In an embodiment, the rotation speed is adjusted to keep a detachment point of the welding wire in a substantially constant position with respect to the rotation axis.

In an embodiment, rotation of the welding wire around its longitudinal axis between a detachment point and the guiding direction is below 10°.

In an embodiment, the method comprises the step of welding with the dispensed welding wire using a welding torch, wherein torsion forces in the welding wire between a detachment point and the welding torch remain below a yield strength of the welding wire. In an embodiment, the method comprises the step of welding with the dispensed welding wire without rolling the welding wire for straightening.

In an embodiment, the method is performed using a welding wire dispenser according to any of the embodiments described herein and/or using a system for providing welding wire according to any of the embodiments described herein, for providing welding wire to a welding robot.

The invention provides a use of a system a system for providing welding wire according to any of the embodiments disclosed herein, for example according to any of claims 22-23, for reducing twist in a welding wire comprising aluminium, tin, zinc or alloys thereof.

The invention further provides a method for providing a welding station, for example a welding robot, with a welding wire dispenser according to any of the embodiments descried herein, for example according to any of claims 1-21. The welding wire dispenser may advantageously be retrofitted to an existing welding station, for example, by removing an existing wire dispenser and arranging a coiled welding wire in a drum in a welding wire dispenser according to an embodiment as described herein, whereby the respective welding wire is provided to a welding torch of the welding station.

Brief description of drawings

Further characteristics of the invention will be explained below, with reference to embodiments, which are displayed in the appended drawings, in which:

Figure 1 A schematically depicts a perspective view of a welding wire dispenser without motor, sensor or controller;

Figure 1 B schematically depicts a top view of the welding wire dispenser according to the embodiment of Figure 1A;

Figure 2A schematically depicts a perspective view of a system for providing welding wire according to an embodiment of the present invention;

Figure 2B schematically depicts a side view of a partial cross section of the welding dispenser of the embodiment of Figure 2A;

Figure 3A schematically depicts a top view of a welding drum with coiled welding wire according to the embodiment of Figures 1A-1 B, wherein the welding wire is dispensed;

Figure 3B schematically depicts a top view of a welding drum with coiled welding wire according to the embodiment of Figures 2A-2B, wherein the welding wire is dispensed;

Figure 4 schematically depicts a partial detailed view of a welding wire dispenser according to another embodiment of the present invention; Figure 5 schematically depicts a partial detailed view of a welding wire dispenser according to another embodiment of the present invention and

Figure 6 schematically depicts an embodiment of a feedback control loop of a controller according to an embodiment of the present invention.

Throughout the figures, the same reference numerals are used to refer to corresponding components or to components that have a corresponding function.

Detailed description of embodiments

Figures 1A and 1 B schematically depict a welding wire dispenser for dispensing, from a welding wire stack 9T in wire drum 90, welding wire 91. The wire drum 90 is a stationary welding wire enclosure, i.e. that is normally positioned stationary on the ground. The stationary welding wire enclosure is positioned on a stage 92 having a support 92’ that is rotatably mounted on the stage 92 around a rotation axis r. A fixed wire guide 94, 95 is provided, consisting of first part 94 pointing in the wire drum and a second part 95 that guides the welding wire towards a welding station. A stack of welding wire 91 is provided in the welding drum. The welding wire 91 is provided as a coiled welding wire stack 9T, i.e. the welding wire 91 is not wound around the welding wire enclosure 90, but is provided therein. The welding wire stack 9T surrounds a hollow interior space 91”.

As a result of e.g. fluctuations in the supply rate of welding wire 91 required for the welding station and variations in the condition of the wire and/or the welding wire enclosure, the welding drum 90 may not rotate sufficiently to keep up with the welding wire supply rate, causing variations in curve radius C of the welding wire 91. In particular, a relatively small curve radius C1 may occur, as depicted in Figure 3A.

This may cause twist in the wire, especially in case of relatively soft welding wires such as aluminium, causing plastic deformation of the welding wire 91.

Figures 2A and 2B depict a welding wire dispenser 1 for supplying a coiled welding wire 91 from a welding wire enclosure, in this embodiment a wire drum 90 provided with aluminium welding wire 9T stacked in coils in the enclosure, defining a hollow interior spac. In Fig. 2A, a roller 97 is provided, which is conventionally used to straighten supplied welding wire 91.

The welding wire dispenser 1 comprises a turntable 2 for supporting the welding wire enclosure 90. The turntable 2 comprises a support part 21 that is rotatable with respect to a stationary part 22. The turntable 2 has a motor 23 for rotating the support part 21 with respect to the stationary part 22 around a vertical rotation axis r to rotate the welding wire enclosure 90 around the rotation axis r with a rotation speed to dispense welding wire 91. The turntable 2 comprises a controller 24 to control the rotation speed. The controller 24 may also be provided outside of the turntable, for example externally.

The movable part 21 of the turntable 2 comprises a flat support surface 25 for the wire drum 90 to rotate with the rotational speed R of the movable part 21 of the turntable 2.

The welding wire dispenser 1 comprises a wire guide 3 associated with the turntable and movable at least in a direction parallel to the rotation axis r, for guiding the welding wire 91 out of the welding wire enclosure 90 from a pickup direction P2 transverse to the rotation axis r towards a stationary guiding direction G having a component in the direction of the rotation axis. In this embodiment, the guiding direction is parallel to the rotation axis. From the guiding direction G, further guides 95 lead the welding wire 91 to a welding station, for example to a welding torch 96 thereof.

The wire guide 3 comprises a rotatable bearing 31 arranged on the axis of rotation 4, and is rotatable around the axis of rotation r of the turntable 2, such that a pickup direction P1 P2 of the wire guide 3 is variable.

The wire guide 3 defines a path from the pickup direction P2 towards the guiding direction G that is aligned with the rotation axis r. The wire guide 3 comprises a curved, hollow tube that extends between an inlet defining the pickup direction P2 and an outlet defining the guiding direction G.

The welding wire dispenser 1 comprises a support element 5 that is configured to be positioned inside a wire drum 90 on top of a welding wire stack 9T. The support element 5 is associated with the turntable 2 and movable in the direction parallel to the rotation axis r. The support element 5 is floating, i.e. supported by the welding wire stack 9T, and comprises a positioning surface 51 to be positioned against the welding wire stack 9T in the wire drum 90, such that the guide element 3 remains supported on top of the wire stack 9T in the wire drum 90 when the height of the welding wire stack 9T decreases.

A diameter of the support element 5 is slightly less than a diameter of the welding wire enclosure 90, for example slightly less than 0,52-0,75 m, such that the support element 5 remains aligned in the welding wire enclosure 90with respect to the rotation axis r.

The wire guide 3 is configured to be positioned at least partially in the welding wire enclosure, in particular above the hollow interior space 91” surrounded by the welding wire stack 9T when the support element 5 is arranged on top of the wire stack 9T with the positioning surface 51. The wire guide 3 is rotatably mounted, centrally in the support element 5, by means of the rotatable bearing 31, for example a ball bearing. This way, the wire guide

3 is configured to follow the top layer of welding wire in the direction parallel to the rotation axis. The support element 5 is configured to align the guide element 3 with respect to the rotation axis r in the welding wire enclosure 90 and has a width that is equal to or slightly smaller than an inner diameter of the welding welding wire enclosure 90.

The wire guide 3, from the outlet towards the inlet, extends from the floating support element 5 along the rotation axis r and bends sideways away from the rotation axis r.

The wire guide comprises a measurement surface S provided with a marker 33. The measurement surface S is arranged on the outer surface of the wire guide 3 and protrudes radially therefrom, transverse to the rotation axis r. The measurement surface S rotates with the wire guide 3. The marker 33 is an optical reflector, but other types of visual markers are also possible.

The sensor 4 is configured to measure the movement signal by detecting the marker 33, such that detection represents rotation of the wire guide 3.

The welding wire dispenser 1 comprises a sensor 4 operatively connected to the controller 24 for measuring a movement signal representative for movement of the wire guide 91. The controller 24 is configured to adjust the rotation speed R of the motor 23 in dependence of the measured movement signal to keep wire tension below a yield strength of the welding wire 91. The controller 24 is configured to activate and deactivate the motor 23 of the turntable and to vary a rotation speed thereof. The sensor 4 is configured to measure rotation movements of the wire guide 3 around the rotation axis r that are representative for movement of the wire guide 91.

The sensor 4 is an optical sensor configured to measure a circumferential position of the guide element 3 around the rotation axis r. As the rotation axis r is determined by the turntable 2, the sensor is arranged to measure rotation of the wire guide 3 with respect to the stationary part 22 and the surroundings. However, in other embodiments, the sensor may also be of another type, such as a load cell arranged to measure load exerted by the welding wire 91 on the wire guide 3.

The optical sensor 4 is configured to measure movements of the wire guide 3 at a distance therefrom, and is arranged at a height of above the turntable that is larger than the height of the welding wire enclosure 90, for example more than the height of the welding wire enclosure of 0,39-1 ,1 m. This way, a wire drum may be provided between the turntable and the optical sensor conveniently. at least 0.5 m above the turntable 2, in particular at least 1,0 m. The sensor 4 comprises a laser light source configured to emit a laser beam 41 and is configured to capture laser light reflected by the reflector 33.

The welding wire dispenser 1 comprises a second sensor 4’ operatively connected to the controller 24 for measuring a second movement signal representative for movement of the wire guide. Further, a third sensor 4” is provided which operates similarly, having a laser beam 41”. In other embodiments, more or less sensors may be provided. The laser beams 41 , 4T, 41” are shown at a finite length, but may in practice reach further, for example up to flat support surface 25, such as reach at least 0,29-1 ,0 m.

The first sensor 4, the second sensor 4’ and the third sensor 4” are arranged at a distance from each other. When a new welding wire stack is provided, the reflector 33 may be arranged in between the beams 41 and 4T and/or 41”, such that detection of the reflector 33 by the first sensor 4, the second sensor 4’ or the third sensor 4” represents a change in position of the wire guide 3 and therefore movement. Detection of the reflector 33 of the wire guide 3 by one of the multiple sensors 4, 4’, 4” is representative for a respective position of the wire guide 3.

This way, the speed of the motor 23 may be increased or decreased depending on a supply rate, such that a curve radius C may be held relatively constant, for example at a constant radius C2 that is sufficiently large to avoid plastic deformation of the welding wire 91 , such that the chances of introduction and aggravation of deformation and/or residual stresses in the welding wire can be reduced.

The controller 24 is configured to adjust the rotation speed R of the turntable 2 with respect to the wire guide 3, in particular with respect to the rotatable bearing 31 thereof, to keep the wire guide 3 relatively stationary, i.e. without rotation around the rotation axis r, and thus to keep the wire tension below and/or around a predefined threshold value.

The controller is configured to adjust the rotation speed R such that the welding wire 91 is removed from the coiled welding wire stack 9T in a relatively constant pickup direction P2, for example in a pickup direction having a relatively constant angle with respect to the coiled welding wire stack 9T, as shown in Figure 3B as angle between uncoiling direction U2 at detachment point d2 and pickup direction P2.

The uncoiling direction U1, U2 at respective detachment points d1, d2 is determined by the tangent at an detachment point d1 , d2 of the welding wire 91, i.e. were the welding wire 91 is detached from the rest of the welding wire stack 9T.

The controller 24 is configured to increase the rotation speed R when the movement signal represents a relatively high wire tension, for example when the wire tension exceeds the threshold value, i.e., in this embodiment, the threshold may be programmed in the controller and/or be determined by dimensions of the reflector 33 and positions of the sensor 41 , 4T 41” with respect to the reflector 33. The movement signal 33 depends on the reflection of the beam 41 , 41’, 41” such that it is dependent on movement of the wire guide 3. The controller 24 is configured to decrease the rotation speed R when the movement signal represents a relatively low wire tension, for example when the wire tension falls below a threshold value. Multiple threshold values and/or more advanced control configurations may be used. In this embodiment, the speed of the motor 23 may be reduced when rotation of the reflector in direction R is detected in the movement signal, and the motor 23 may be deactivated by the controller when reflection of the beam 41” is detected by the third sensor 4” and provided in the third movement signal. The speed of the motor 23 may be increased when reverse rotation of the reflector in the movement signal, and speed of the motor 23 may be further increased by the controller when reflection of the beam 4T is detected by the second sensor 4’. This way, multiple threshold values are provided by the second sensor 4’ and third sensor 4”.

The rotation speed is adjusted to keep a detachment point of the welding wire in a substantially constant position with respect to the rotation axis. Rotation of the welding wire around its longitudinal axis between a detachment point and the guiding direction is below 10°. Torsion forces in the welding wire between a detachment point and the welding torch remain below a yield strength of the welding wire.

In use, upon uncoiling from the coiled welding wire stack 9T with the welding wire dispenser 1, the welding wire 91 is relatively straight. The is limited or no twist in the welding wire 91 such that wire straighteners are not necessary.

Figure 4 schematically depicts a partial detailed view of a welding wire dispenser according to another embodiment of the present invention. The sensor 4 is attached to the wire guide 3. The sensor 4 comprises a three-axis accelerometer, a three-axis magnetometer and a three-axis gyroscope. The movement signal comprises one or more of an accelerometer signal, a magnetometer signal and/or a gyroscope signal and represents combined positions, velocities, respectively accelerations around the rotation axis r measured by the sensor 4. The sensor 4 is provided with a battery and is configured to communicate wirelessly with a controller 24 via Bluetooth.

Figure 5 schematically depicts a partial detailed view of a welding wire dispenser 1. The welding wire dispenser 1 functions similarly to the embodiment of figures 2A-2B. However, the measurement surface S is formed by an elongate hollow tube attached to the wire guide 3 and rotating therewith. The welding wire 91 is guided through the elongate hollow tube. The measurement surface S is provided with markers consisting of contrasting lines 34. The measurement surface S is located perpendicular to the rotation axis r, such that the markers 34 rotate with the wire guide 3 along the rotation axis r.

The optical sensor 4 comprises a light source that emits a light beam 41 and a camera. The sensor 4 is configured to measure movement of the wire guide using computer vision by observing movement of the contrasting lines 34.

The elongate hollow tube is has a relatively large height, and is for example as high as the coiled welding wire stack 9T, such that when the support element 5 moves downward with reducing height of the welding wire stack 9T, the light beam 41 still reaches the measurement surface S and the sensor 4 can still measure the measurement surface S by detecting markers 34.

Figure 6 schematically depicts an embodiment of a feedback control loop of a controller according to an embodiment of the present invention.

The amount of welding wire used by a welding system, for example by welding torch 96, influences the circumferential position (P1) of the guide element (3). This effect is countered by rotation of the motor (23) of the turntable (2). The sensor (4) is configured to measure the circumferential position (P1). A setpoint value (PO) is provided to the controller, e.g. by programming or determined by the design of the welding wire dispenser (1). For example, the setpoint value (PO) may be determined by the position of the sensor (4).

The controller 24 is configured to determine a difference (a) between the measured circumferential position (P1) of the guide element (3) and a setpoint value (PO), and to adjust the rotation speed (R) in dependence of the determined difference. The controller (24) is a PID controller. The controller (24) is configured to send a signal to the motor (23) to increase or reduce the rotation speed (R).