WO2014147054A1

WO2014147054A1 - Handheld welding torch apparatus with a welding tip pivotally mounted relative to the nozzle section

Info

Publication number: WO2014147054A1
Application number: PCT/EP2014/055373
Authority: WO
Inventors: Åge INGEBRETSEN
Original assignee: Nordic Welding Solutions As
Priority date: 2013-03-20
Filing date: 2014-03-18
Publication date: 2014-09-25
Also published as: NO334406B1; NO20130410A1

Abstract

The present invention concerns a welding torch apparatus, in particular a handheld welding torch apparatus with possibilities of weaving. The inventive apparatus comprises a nozzle (2) section for feeding of a welding wire to a workpiece during a welding operation and a handle section enabling handheld, manual operation of the welding torch apparatus during the welding operation, which handle section is attached to the nozzle section (2). The nozzle section (2) further comprises an elongated welding tip (4) displaying a channel (5) for the welding wire, wherein the channel (5) debouches at a free end of the welding tip (4) to enable feeding of the welding wire in a feed direction. The welding tip (4) of the apparatus is pivotally mounted in the nozzle section (2) in a joint (41-43) enabling the free end of the welding tip (4) to be pivoted about a first axis (x) and an orthogonal second axis. Furthermore, the welding torch apparatus comprises an actuator for actuating the welding tip (4) about the first axis (x) and the second axis enabling a movement of the free end along a first direction and along an orthogonal second direction, which first direction and second direction are orthogonal to the feed direction of the welding wire.

Description

Title:

HANDHELD WELDING TORCH APPARATUS WITH A WELDING TIP PIVOTALLY MOUNTED RELATIVE TO THE NOZZLE SECTION

Field of the invention

The present invention relates to a handheld welding torch apparatus for performing welding with weaving. The apparatus comprises a nozzle section for feeding of a welding wire to a workpiece during a welding operation and a handle section enabling handheld, manual operation of the handheld welding torch apparatus. The handle section is attached to the nozzle section, and the latter comprises an elongated welding tip displaying a channel for the welding wire, wherein the channel debouches at a free end of the welding tip to enable feeding of the welding wire in a feed direction,

Background of the invention

Handheld welding torches have been commercially available for decades. An early example of a handheld arc welding torch is disclosed in GB786648 wherein an electric motor provides continuous feed of a welding wire.

More recently the application of a weaving welding method has become more common, particularly in consumable electrode-type arc welding. In this method a welding torch is weaving (rocking) in a direction transversely of a welding line in order to improve welding accuracy of a workpiece and to obtain a long leg length. To ensure high quality weaving, welding robots have been extensively used in which the robot enforce an oscillating movement on the welding torch directed substantially perpendicularly to a welding line while simultaneously performing a translational movement along the line. Examples of such a robot assisted weaving of welding torches are found disclosed in US5887122A, EP0338078A1, EP0354969 A1 and US4677276A.

However, for handheld welding torches an oscillating movement of the torch itself would be highly impractical since the need for operating the torch by hand sets strict limitations concerning size and weight.

The main object of the invention is therefore to provide a compact and light weight welding torch for handheld welding operations, having the possibility of performing various automatic weaving such as linear and circular weaving in order to obtain similar advantageous as seen in the field of robot welding. There exist today solutions where the control and actuation of the weaving operation is performed internally within the welding torch, thereby requiring only a translational movement of the torch along the welding line. For example US 2011/0174805 A1 and DE 4315782 A1 both disclose weaving torch devices that enable weaving of the welding tip by a combination of electromagnets and springs. These solutions are complex and sets limitations on the available weaving directions. Another known challenge during welding operations with weaving is to maintain high quality welding also in less accessible locations along the welding line, for example when surpassing corners, since these locations often necessitates rotation of the torches, thereby resulting in an undesirable change in weaving direction. A solution to this problem has been addressed in the non-patent publication "Cost Saving Application Ideas For Cutting And Welding" by Bug-0 Systems (US), where part of the welding device is rotated when sharp edges such as corners are encountered. The operator of the welding device initiates the rotation by pressing down a foot paddle. However, this solution is not practical for handheld welding torches. Another object of the invention is therefore to provide a solution to the challenge of maintaining high quality welding with weaving in less accessible locations as described above, also in the case of handheld weaving torches. Summary of the invention

The above-identified objects are achieved by an apparatus as defined in claim 1. Further beneficial features are defined in the dependent claims. In particular, the present invention concerns a welding torch apparatus, in particular a handheld welding torch apparatus, with possibilities of weaving. The inventive apparatus comprises a nozzle section for feeding a welding wire to a workpiece during a welding operation and a handle section enabling handheld, manual operation of the welding torch apparatus during the welding operation, which handle section is at least indirectly attached to the nozzle section. The nozzle section further comprises an elongated welding tip displaying a channel for the welding wire, wherein the channel debouches at a free end of the welding tip to enable feeding of the welding wire in a feed direction (w). The welding tip of the apparatus is pivotally mounted in the nozzle section in a joint enabling the free end of the welding tip to be pivoted about a first axis (x) and an orthogonal second axis (y) . Furthermore, the welding torch apparatus comprises an actuator for actuating the welding tip about the first axis (x) and the second axis (y) enabling a movement of the free end along a first direction (a) and along an orthogonal second direction (b), which first direction (a) and second direction (b) are orthogonal to the feed direction (w) of the welding wire. The apparatus preferably comprises a control unit for controlling the amplitude and the frequency of the movement of the free end in the first direction and/or the second direction. This control unit may further comprise manually operable control means allowing the operator to set the amplitude and/or the frequency of the movement of the free end in the first direction and or the second direction during a welding operation. These control means is preferably positioned in or at the handle section.

The amplitude of the movement of the free end (i.e. the amount of deflection from the centre point of the free end) in the first direction and/or the second direction can advantageously be set by the operator using the control means to be within defined amplitude intervals, for example within 0-15 mm, more preferably between 0-7 mm, such as within 0-3.5 mm. Specific examples of amplitude intervals are 0-15 mm, 0- 14 mm, 0-13 mm, 0-12 mm, 0-11 mm, 0-10 mm, 0-9 mm, 0-8 mm, 0-7 mm, 0-6 mm, 0-5 mm, 0-4 mm, 0-3 mm, 0-3.5 mm, 0-2 mm and 0-1 mm.

The frequency of the movement of the free end in the first direction and/or the second direction can preferably be set by the operator using the control means to be within defined frequency intervals, for example within 0-5 Hz, more preferably within 0-2 Hz, such as within 0-1 Hz. Specific examples of frequency intervals are 0-5 Hz, 0-4.5 Hz, 0-4 Hz, 0-3.5 Hz, 0-3 Hz, 0-2.5 Hz, 0-2 Hz, 0-1.5 Hz, 0-1 Hz, 0- 0.75 and 0-0.5 Hz.

Furthermore, the amplitude and the frequency of the movement of the free end in the first direction and the second direction can preferably be set by the operator using the control means such that the movement of the free end is any movement which may be obtained from a superposition between the first and second direction, such as a linear movement, a circular movement or an elliptical movement.

In another preferred embodiment the control unit comprises orientation or motion sensing means such as accelerometer or gyroscope for measuring the orientation of the apparatus during a welding operation, and in that the control unit, using orientation signals from the orientation sensing means, is arranged to maintain the set movement of the welding tip independent of the movement of the welding torch apparatus.

The choice of orientation sensing means is preferably such that it will be particularly adapted for measuring the orientation of the torch apparatus in three dimensional space, for example by a 3 -axis gyroscope, and that the control unit is particularly adapted to maintain the set movement of the welding tip in three dimensional space.

The control unit is advantageously arranged to set the amplitude of the movement and/or the frequency of the movement of the free end as a function of a welding current and/or a welding wire feed speed of the apparatus. This may be implemented to replace or combine with any additional manually operable control means dedicated for such amplitude/frequency settings.

In a further preferred embodiment the actuator comprises:

- a first tension wire and a second tension wire, which are attached to the welding tip at the joint for pivoting the welding tip about the first axis by means of a first position controlling means attached to the first tension wire and a second position controlling means attached to the second tension wire, and

- a third tension wire and a fourth tension wire, which are attached to the welding tip at the joint for pivoting the welding tip about the second axis by means of a third position controlling means attached to the third tension wire and a fourth position controlling means attached to the fourth tension wire.

The movement of at least one of the position controlling means are preferably controlled by at least one servomechanism.

However, the joint may be actuated by other non-mechanical force providing means such as hydraulic cylinders, pneumatic cylinders and/or magnetic devices. It is also possible to use a combination of different mechanical and non-mechanical force providing means to obtain the desired pivoting of the joint. Likewise, alternative control mechanisms for controlling the position controlling means are envisaged, for example by use of at least one stepper motor.

In the following description, numerous specific details are introduced to provide a thorough understanding of the embodiments of the claimed apparatus. One skilled in the relevant art, however, will recognize that these embodiments can be practiced without one or more of the specific details, or with other components, systems, etc. In other instances, well-known structures or operations are not shown, or are not described in detail, to avoid obscuring aspects of the disclosed embodiments.

Brief description of the drawings

Figure 1 is a schematic view of the handheld welding torch apparatus according to the invention, Figure 2 is a cutaway view of the front part of the handheld welding torch apparatus according to the invention,

Figure 3 is a perspective view of inter alia the nozzle and the welding tip situated inside the front part shown in figure 2,

Figure 4 is a cutaway side view of the handheld welding torch apparatus according to the invention showing servomechanisms and wires used for controlling the movements of the nozzle and

Figure 5 is a top view of the handheld welding torch apparatus shown in figure 4. Detailed description of a preferential embodiment The handheld welding torch apparatus 1 in Figures 1-5 comprises a nozzle 2 and a handle 3 interconnected by a connector tube 10, the latter illustrated as a swan-neck. The handle 3 enables handheld, manual operation of the torch 1 during any welding operation. The handle 3 is formed as an elongated object having the connecter tube 10 and nozzle 2 attached to one of the longitudinal sides and any required communication and power cables 31 attached to the other longitudinal side. The handle 3 is preferably shaped to fit the inside of a human hand to increase the usability. As can be seen in Figure 1 the handle 3 is also provided with a switching device 9 in the form of a toggle switch, wherein the toggle switch 9 is mounted in such a manner that it can be easily reached by the operator / welder, for example by the use of an index finger, i.e. situated on the lower side of the handle, close to the swan-neck 10. Such a single switching device 9 may advantageously have a multifunctional purpose as will be explained in further details below.

Figure 2 shows a cutaway drawing of the nozzle 2. The interior components of the nozzle section 2 comprise a welding tip 4 displaying a channel 5 for accommodating a welding wire 100. The channel 5 debouches at a free end 6 of the welding tip 4 to allow the welding wire 100 to be fed in a feed direction denoted with the axis w in Figure 2. The Figures 2 further shows that the nozzle section 2 contains a joint 7 in the form of a ball bitch that is pivotable about a first axis (x) and an orthogonal second axis (y) (figure 3). The pivoting movements of the joint 7 is enabled by actuation of an actuator 8 (figure 4,5) causing a pushing and/or pulling force on one or more sides of the joints 7, which again results in sweeping movements of the welding tip 4. These movements are in Figure 3 denoted as first direction a and second direction b The pushing and/or pulling takes place on various dedicated, orthogonally oriented, protrusions or lever arms 41-44 situated on the joint 7. By perforating appropriate pivoting movements of the joint 7, and hence causing sweeping movements of the welding tip's 4 free end 6 along directions a and/or b, any weaving movements such as linear movements, circular movements or elliptical movements may be achieved. The amount of force exerted on the joint 7 determines the geometrical extend or sweeping angle of the weaving motion, where the maximum obtainable extension is reached when the welding tip 4 abuts the inside wall of the nozzle cover 2b. Other limitations of the maximum obtainable extension may of course be envisaged, for example limitations due to any protrusions situated inside the nozzle cover 2 and/or protrusions extending from the welding tip 4 and/or limitations set by the actuator 8. In Figures 2 and 3, x, y and w define an orthogonal coordinate system having a common origin in the center of the joint 7. The x,y-axes and the w-axis intersect the origin and the protrusions 41-44, and the origin and the center point of the free end 6, respectively.

Figure 3 further shows a plurality of welding current cables 30. These cables 30 are electrically connected to any power cables 31 extending inside the handle 3 through a feeding pipe 50 (see figure 4 or 5). As an alternative to the illustrated welding current cables 30, other current conducting means may be used such as a ball joint passage made of cupper and graphite.

The configuration and operation of the actuator 8 will now be described in further details with reference to figure 4 and S.

Figure 4 shows a cutaway side view of the handheld welding torch apparatus 1 including at least some of the components situated inside the handle section 3. These components includes the actuator 8 controlling the movement of four tension wires 20-24 attached at their free ends to the before mentioned protrusions 41-44 on the joint 7. Situated below the feeding pipe 50 is shown a gyroscope 90 for registering the orientation of the handle 3, a circuit board 70 comprising the necessary electronic components to perform any desired signal processing and a current measurement device 80 for measuring welding current. The latter device 80 can be any current measurement devices that allows measurements of current levels typical for consumable electrode-type arc welding, that is between 5 to 500 Amperes. An example of such a device is a current transformer (CT).

The gyroscope 90 installed inside the handle 3 continuously registers the direction of the handheld welding torch 1 relative to a reference. Such a reference may be the torch orientation when the operator initiates the flame arc. If the operator deviates from this initial torch orientation, the gyroscope 90 will, if in operation, communicate the registered data for the changed orientation to a processing unit on the circuit board 70, which again will send corrected input data to the servomechanisms 28,29. These corrected data will then adjust the orientation of the weaving in order to maintain the initial weaving angle(s) and position relative to the reference / welding line. In alternative embodiments the movements of the joint 7 may be actuated by other means such as by stepper motors, hydraulic or pneumatic cylinders or electromagnets.

In a preferred embodiment the handheld welding torch apparatus 1 is configured such that the toggle switch 9 arranged on the handle 3 performs the following operations during use: Pressure on the toggle switch 9, causing a complete inward movement:

the welding current toggles between flow and interruption within the cables 30, thereby initiating and stopping the flame arc between the tip of the welding wire 100 and the workpiece. Multiple pressures on the toggle switch 9, causing a non-complete inward movement:

First non-complete pressure: The welding tip 4 changes from a rest position to a rotational movement of welding tip with an initial predefined weaving diameter. Second non-complete pressure: The welding tip 4 changes from a rotational movement with small weaving diameter to a rotational movement with a larger predefined weaving diameter relative to the initial predefined weaving diameter.

Third non-complete pressure: The welding tip changes from a rotational movement with larger weaving diameter to a linear movement with an initial predefined deflection length.

Fourth non-complete pressure: The welding tip changes from a linear movement with an initial predefined deflection length to a linear movement with a larger predefined deflection length relative to the initial predefined deflection length. Fifth non-complete pressure: The welding tip changes from a linear movement with the larger predefined deflection length to a rest position In this particular embodiment the two predefined weaving diameters and the two predefined deflection lengths are set by a dedicated operation software and may be changed prior and/or during welding. Furthermore, the velocity of the weaving is preferably set by the actual welding current, the latter value being measured by known current measurement devices 80, for example Hall effect current measurement devices in combination with low pass filters. As an alternative, or as an addition, the weaving velocity may be a function of the set feed velocity of the welding wire 100.

In yet an alternative embodiment, these and other operations may be performed by further dedicated manually operable control means arranged on the handle 3, such as applying additional switching or sliding devices. For example, the handle 3 may include a wheel or slide arranged in a position on the handle 3 that is easily reachable by the welders thumb during operation, for example on the top part of the handle 3 close to the swan-neck 10, in order to enable adjustment of the above mentioned weaving diameters, deflection lengths, weaving velocity, or any combinations thereof.

Figure 5 gives a cutaway view of the handheld welding torch apparatus 1 similar to the apparatus shown in figure 4, but now in top view. The four tension wires 20-24 is in this figure clearly seen to extend from the actuator 8 and into the swan-neck 10 for connection to the protrusions 41-44 on the joint 7 (see Figures 2,3). The actuator 8 comprises is this embodiment a first servomechanism 28 and a second servomechanism 29, where the first and second servomechanism 28,29 further comprises a first and second position controlling device 24,25 and a third and fourth position controlling device 26,27, respectively, here in the form of lever arms. The programming of the servomechanisms 24,25, and thus the movement of the position controlling devices 24-27, by the signal communicating circuit board 70 enables the wide range of weaving movements of the welding tip 4.

In the preceding description, various aspects of the apparatus according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention.

Claims

CLAIMS 1. A welding torch apparatus (1), comprising:

- a nozzle section (2) for feeding of a welding wire (100) to a workpiece during a welding operation, and

- a handle section (3) enabling handheld, manual operation of the welding torch apparatus (1) during the welding operation, which handle section (3) is attached to the nozzle section (2),

wherein the nozzle section (2) comprises an elongated welding tip (4) displaying a channel (5) for the welding wire, wherein the channel (5) debouches at a free end (6) of the welding tip (4) to enable feeding of the welding wire in a feed direction (w), characterised in that:

- the welding tip (4) is pivotally mounted in the nozzle section (2) in a joint (7) enabling the free end (6) of the welding tip (4) to be pivoted about a first axis (x) and an orthogonal second axis (y), and in that

- the welding torch apparatus (1) comprises an actuator (8) for actuating the welding tip (4) about the first axis (x) and the second axis (y) enabling a movement of the free end (6) along a first direction (a) and along an orthogonal second direction (b), which first direction (a) and second direction (b) are orthogonal to the feed direction (w) of the welding wire.

2. The welding torch apparatus (1) according to claim 1, characterised in that it comprises a control unit (9,70) for controlling the amplitude and the frequency of the movement of the free end (6) in at least one of the first direction (a) and the second direction (b).

3. The welding torch apparatus (1) according to claim 2, characterised in that the control unit (9,70) comprises manually operable control means (9) allowing the operator to set at least one of the amplitude and the frequency of the movement of the free end (6) in least one of the first direction (a) and the second direction (b) during a welding operation.

4. The welding torch apparatus (1) according to claim 3, characterised in that the control means is positioned in the handle section (3).

5. The welding torch apparatus (1) according to any one of claims 2-4, characterised in that the amplitude of the movement of the free end (6) in at least one of the first direction (a) and the second direction (b) can be set by the operator using the control means (9) to be within the interval 0-7 mm.

6. The welding torch apparatus (1) according to any one of claims 2-5, characterised in that the frequency of the movement of the free end (6) in at least one of the first direction (a) and the second direction (b) can be set by the operator using the control means (9) to be within the interval 0-2 Hz.

7. The welding torch apparatus (1) according to any one of claims 2-6, characterised in that the amplitude and the frequency of the movement of the free end (6) in the first direction (a) and the second direction (b) can be set by the operator using the control means (9) such that the movement of the free end (6) is a linear movement.

8. The welding torch apparatus (1) according to any one of claims 2-6, characterised in that the amplitude and the frequency of the movement of the free end (6) in the first direction (a) and the second direction (b) can be set by the operator using the control means (9) such that the movement of the free end (6) is a circular movement.

9. The welding torch apparatus (1) according to any one of claims 2-8, characterised in that the control unit comprises orientation sensing means (90) for measuring the orientation of the apparatus (1) during a welding operation, and in that the control unit (9,70), using orientation signals from the orientation sensing means (90), is arranged to maintain the set movement of the welding tip (4) independent of the movement of the welding torch apparatus (1).

10. The welding torch apparatus (1) according to claim 9, characterised in that the orientation sensing means (90) is particularly adapted for measuring the orientation of the apparatus in three dimensional space, and that the control unit (9,70) is particularly adapted to maintain the set movement of the welding tip (4) in three dimensional space.

11. The welding torch apparatus (1) according to any one of claims 2-10, characterised in that the control unit (9,70) is arranged to set at least one of the amplitude and the frequency of the movement of the free end (6) as a function of at least one of a welding current and a welding wire feed speed of the apparatus (1).

12. The welding torch apparatus (1) according to any one of the preceding claims, characterised in that the actuator (8) comprises:

- a first tension wire (20) and a second tension wire (21), which are attached to the welding tip (4) at the joint (7) for pivoting the welding tip (4) about the first axis (x) by means of a first position controlling means (24) attached to the first tension wire (20) and a second position controlling means (25) attached to the second tension wire (21), and a third tension wire (22) and a fourth tension wire (23), which are attached to the welding tip (4) at the joint (7) for pivoting the welding tip (4) about the second axis (y) by means of at least a third position controlling means (26) attached to the third tension wire (22) and at least a fourth position controlling means (27) attached to the fourth tension wire (23). . The welding torch apparatus (1) according to claim 12, characterised in that the movements of at least one of the first, second, third and fourth position controlling means (25-28) are controlled by at least one servomechanism (28,29).