CA2700760A1

CA2700760A1 - Hose assembly

Info

Publication number: CA2700760A1
Application number: CA2700760A
Authority: CA
Inventors: Emil Schubert
Original assignee: Individual
Current assignee: Alexander Binzel Schweisstechnik GmbH and Co KG
Priority date: 2008-03-18
Filing date: 2009-03-10
Publication date: 2009-09-24
Also published as: BRPI0904331A2; AU2009226651A1; DE102008014814A1; WO2009115208A1; JP2011500332A; EP2158058A1; CN101801582A; DE102008014814B4; KR20100132481A

Abstract

The invention relates to a hose assembly (1) of an arc welding or cutting torch, having a plurality of current-conducting leads (25, 44), wherein the leads (25, 44) comprise an aluminum wire, the current-conducting leads (25, 44) are accommodated in a channel, and wherein the hose assembly (1) has a channel (5, 22) for guiding a welding wire (6, 21).

Description

Specification: Hose Assembly The invention relates to a hose assembly for an arc welding or cutting torch having a plurality of current conducting leads, wherein the leads comprise an aluminum wire, the current conducting leads are accommodated in a channel, and wherein the hose assembly has a channel for guiding a welding wire.

Prior Art Arc welding and cutting torches have long been known in the prior art. Welding and cutting torches of this type can be embodied for manual or automated welding.
Most arc welding and cutting torches for manual use comprise a base and a hand piece, which are connected to one another via a hose assembly. With manual arc welding and cutting torches, it is essential for the hand piece to be as freely movable as possible. The material must therefore have especially good reverse fatigue strength under bending and twisting stress.

Arc welding and cutting torches for automated welding are frequently siructured as robots comprising a movable robotic arm which moves up to areas to be welded. In such cases, a hose assembly is provided between a base and an actuator. With automated welding, the robotic arm frequently operates at high acceleration, which increases the speed of welding. The hoses swing freely within certain limits, and are thus exposed to high mechanical stresses.

Welding requires high levels of electrical power, which must be transported via power cables from the base to the hand piece. In the prior art, only copper is used for power cables for arc welding and cutting torches due to its high electrical conductivity. Another property of copper is its high thermal conductivity, which allows it to rapidly transport away heat that is generated as a result of resistance. Copper also fulfills the necessary requirements with regard to mechanical properties. In the prior art, the power cables are customarily configured as stranded wires.

It is also known In the art that eiectricai conductors can be produced from all types of metals.

A hose assembiy having the characterizing features initially described is also known from DE 15 15 145 A. For guiding the welding wire, the welding cable contains a sheath made of flexible synthetic materiai and having a completely smooth interior wall.
This sheath is surrounded by a helically wound bundle of copper wires or aluminum wires for conducting current. The wire bundle is encased on the outside by a layer of rubber. To reinforce the cable against tensile stress, the conductor can be encased In steel braiding.

DE 85 09 258 U1 discloses a welding cable in which a portion of the current conducting leads are made of aluminum and another portion of the electrical leads are made of copper. In this case, an inner conductor is made of aluminum, with an outer conductor made of copper coiled onto it.

The copper electrical conductors that are currently being used for hose assemblies have the disadvantage that the electrical conductors make up to 2/3 the total weight of the hose assembly, which can make handling them over long periods of time fatiguing.
Stresses on hose assemblies used for automated welding also increase with the inertial mass of the hose assembly.

DE 20 52 462 B2, DE 211, 24 52 A, US 2006/0102368 A1, US 6 178 623 B1, and US

926 573 describe conductors having an aluminum core onto which a copper layer is applied directly or indirectly as an outer sheath.

DE 85 09 258 U1 concerns a welding cable comprised of two different conductor materials, such as aluminum and copper, wherein a single conductor having a higher conductivity value, density and breaking load, such as copper, is twisted onto a conductor having a lower conductivity value, density and breaking load, such as aluminum.

DE 24 09 322 Al discloses a tubular piece made of rubber-like, flexible and optionalty fire-resistant material configured to acoommodate separate elements and leads that are customarily used in inert gas welding technology, wherein the tubular piece has a plurality of separate channels.

EP 0 076 390 Al also describes a device for use in inert gas welding using fusible wire electrodes. in this case a coaxially structured hose assembly is provided, comprising a welding current lead, control leads and an annular gap which conducts an inert gas. The wire electrode is arranged centered in the hose assembly, inside a gas Impermeable, flexible sheath.

DE 88 06 360 U1 discloses a device for connecting a torch for use in inert gas arc welding, with a hose assembly comprised of power cable, Inert gas line, cooling water intake line, cooling water return line, and switch cable, wherein the end of the hose assembly that faces the torch opens into a housing which contains couplings for the power cable and a cooling water line with a current/water cable for the torch, and couplings for the inert gas line and the other cooling water line with allocated leads for the torch, wherein a coupling for the switch cable is also accommodated in the housing.

DIN EN 60228, September 2005, relates to conductors for cable and Insulated leads, and defines the nominal cross sections for conductors of cables and insulated conductors for electrical power systems. It also contains requirements for the number and dimensions of wires and for resistance values. The conductors comprise single- and multiple-wire conductors made of copper, aluminum and aluminum alloys for permanent installation and flexible copper conductors.

The object of the invention is to propose a hose assembly for an arc welding and cutting torch, which is substantially lighter than hose assemblies containing copper cables known in the prior art, but which has comparatively favorable mechanical properties, especially with regard to torsional or bending stresses.

Presentation of the Invention The object is attained with a hose assembly according to claim 1. Advantageous embodiments are specified in the dependent claims.

The use of copper-coated aluminum wire as the current conducting lead in the hose assembly has the benefit of decreasing the weight of the assembly while at the same time eliminating the occurrence of high temperatures at the transition points between the conductors and the connections. This is presumably attributabie to the fact that the inherently higher transition resistance between aluminum and the respectlve connection is reduced substantially due to the use of the copper on the aluminum wire, thus although 35 a weight reduction is achieved, the electrical and mechanical properties of the eiectricai ......... ...__._. ......... . CA 02700760 2010-03-24 conductor are largely retained, as compared with the use of conventional copper conductors. In this case, multiple current conducting leads are arranged coaxially around a central channel. This enables muitiple functions that the hose assembly will perform to be combined, with a smaller number of individual hoses. This also allows synergistic effects to be achieved, for example if the central channel is used to convey a cooling medium. The current conducting lead, which gives off heat, can then be simultaneousiy actively cooled by the cooling medium. Also provided is a channel for guiding a welding wire. This allows a comparatively large amount of welding wire to be stored in a base station of the welding unit, and for the welding wire to be guided through the hose assembly to the hand piece as needed. A channel for the current conducting lead is also provided. Especially with a coaxial assembly, It can be necessary to spatially separate the individual functions to be performed by the hose, for example because the potential of the current conducting lead is different from that of a welding wire that may be transported in the hose assembly. Moreover, all the channels are arranged coaxially.
This enables the most efficient use of the existing space and produces hose assemblies of smaller diameters, resulting in easier handling. The channel containing the current conducting leads encompasses the channel for conducting the medium, and the channel for conducting the medium encompasses the channel for guiding the welding wire. The medium channel can thus be used for cooling the welding wire channel and the channel containing the current conducting lead at the same time.

Of course, according to one preferred embodiment of the invention, all the current conducting leads of each current conductor are embodied as copper-coated aluminum wires. In this case, the individual conductors can be embodied in the form of individual wires, stranded wires, or the like.

It has also been found that the use of copper-coated aluminum wires in the hose assemblies of the invention is much more cost effective. This is due to the fact that processing is substantially simpiified in a simpiiFied drawing process.
The connectors of the hose assembly can be connected to the current conducting lead or leads via a crimped connection.

However, one preferred variant calls for the current conducting leads with the copper-.35 coated aluminum wires to be connected to the hose assembly connectors by means of ultrasound welding. In that case, the outer stranded wires of the current conducting lead of the hose assembly can be directly closed with a copper sleeve. This connection method has the advantage of lower transition resistances and thus also lower temperature increases at the transition points. This ultrasound welding process can be used both with aluminum wires and with aluminum wires having a layer of copper on their outer sheath. It has also been found that the ultrasound welding process increases the strength of the connections or the sleeves substantially over the strength of a crimped connection. Both copper sleeves and steel sleeves can be used as connectors.

The copper coating on the aluminum wire is advantageously 1 to 100 pm thick.
This measure ensures an optimization of the copper-coated aluminum wire in terms of minimizing its weight with the lowest possible transition resistance.

It has also been determined that with hose assemblies, current conducting leads configured as stranded wires, with the individual wires of these containing aluminum, meet the requirements for use in arc welding and cutting torches.

Hose assemblies according to the invention have the advantage of being substantially lighter than hose assemblies with copper leads, and therefore easier to handle. Despite the required increased volume of aluminum necessary for transmission, the total weight of hose assemblies produced using aluminum stranded wires is substantially lower than the total weight of conventional hose assemblies.

The hose assembly of the invention overcomes a long-standing prejudice held by those in the industry that aluminum cables should not be used in hose assemblies due to their less favorable conductivity properties and due to their flexural and breaking properties.

By configuring the aluminum lead as a stranded wire with relatively fine individual wires, the bending and torsional stresses exerted on each individual wire are lower than with a wire having a larger cross section.

For the individual wires, pure aluminum having a degree of purity of A199 to A199.9 has proven particularly well suited. However, aluminum alloys may also be used.

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At least one composite lead is advantageously provided, which contains individual wires made of copper-coated aluminum or an aluminum containing alloy and individual wires made of copper or a copper containing alloy. Surprisingly, it has been found that composite leads of this type substantially improve the removal of heat from the leads, making the overall cost of the hose assembly even more favorable as compared with pure copper leads.

Advantageously, the lead has at least four individual stranded wires, which are laid around a core strand. A lead having this type of structure is highly flexible, even with large lead cross sections.

Advantageously, each individual stranded wire andlor the core strand are made up of 20 individual wires. This further increases its flexibility and reduces the risk of cable break.
In one advantageous embodiment of the invention, the individual wires have a diameter of 0.05 mm to 0.5 mm. A diameter of 0.15 mm is especially preferable.
Individual wire diameters such as these allow the necessary conduction parameters to be achieved.
Particularly advantageously, the current conducting leads, especially the current conducting stranded wires, are wrapped helically or spirally around a central channel.
Because the current conducting leads or stranded wires extend spirally or helically around the central channel, preferably on fts exterior, in the hose assembly, the flexural stress exerted on the current conducting leads when the hose assembly Is bent, stretched, compressed or twisted is distributed. In particular, twisting the leads or stranded wires around the central channel relieves the stress on the hose assembly in the range of the smallest radius of curvature of the current conducting leads or stranded wires.

The length of lay of the stranded wires Is advantageously 15 mm to 200 mm, with 40 mm to 60 mm being especially preferred. Such lengths of lay improve the mechanical properties of the hose assembly.

Advantageously, at least one additional control current lead is provided. This allows the functions of the welding device to be easily controlled using the hand piece.

6 a Particularly advantageously, at least two channels are provided for conducting a medium, along with at least two current conducting leads. As in the case described above, the combination of medium conducting lead and current conducting lead produces positive effects in terms of the efficiency of current conduction. Providing at least two channels with current conducting leads, wherein the current conducting leads can also be arranged centrally with the medium flowing directly around them, increases the surface of the leads and thus the amount of heat they emit. Moreover, the cross section of the leads can be increased while their flexibility is maintained. This makes it possible to increase the total power that can be transmitted via the hose assembly.
A polymer has proven to be a suitable medium for the channels. Polymers can fulfill the widest range of requirements and have proven effective for long-term use.

The medium is preferably comprised of a gas or a liquid. It can be the process gas, such as the inert gas used in inert gas welding, or a liquid, for example for cooling the hand piece.

The current conducting lead advantageously has a connector at one end which is connected to the current conducting lead via a crimped connection.
Surprisingly, it has been found that crimped connections of this type produce a secure connection between current conducting lead and connector which remains reliable over the long term.

Atternatively or additionally, it is possible for the current conducting lead to be welded to a connector or to a wire end sleeve via ultrasound. It has been found that the copper-coated aluminum wires can be securely connected to connectors not only via crimped connections, but also via ultrasound welding. The latter case results in quasi similar materials at the connecting surfaces, which can be better joined.

Brief Description of the Drawings Additional goals, advantages, characterizing features and potential applications of the present invention are contained In the following description of several exemplary embodiments, in reference to the set of drawings. All described andlor illustrated features, alone or in any logical combination, constitute the subject of the present invention, regardless of how they are combined In the claims or in the references to previous claims.

Figure 1 a cross section of a hose assembly according to the invention;
Figure 2 a cross section of an aftemative embodiment of a hose assembly according to the invention;
Figure 3 an embodiment of a so-called current/water cable according to the invention;
Figure 4 a longitudinal section of a current cable according to the invention;
Figure 5 a cross section of the cable of Figure 4 along the line A-A;

Figure 6 a perspective view of a stranded wire.

Figure 1 showed a schematic representation of a hose assembly 1 according to the invention, such as are used in arc welding or cutting torches, for example. In the exemplary embodiment chosen here, the hose assembly I combines several individual hoses together inside an outer hose 2, and guides these from a base (not shown here) to a hand piece (also not shown here) of the welding device, or from a base of an automated welding device to an actuator.

The hose assembly 1 has a cooling medium intake hose 3, in the interior of which a cooling medium is conveyed from the base to the hand piece or actuator. Also provided is a process gas hose 4, inside which the prooess gas flows to generate an inert gas atmosphere. A wire guiding hose 5 is also provided, which transports a welding wire 6 inside a spiral wire guide 7 provided In the wire guiding hose 5. Also provided is a control lead 8, via which control signals are transmitted from the hand piece or actuator to the base.

A so-called current/water cable 9 is also provided. inside a hose 10 of the current/water cable 9 a current conducting lead 11 is provided, which will be described in greater detail further below. Between the hose 10 and the current conducting lead 11, a channel 12 for cooling medium return is provided. This offers the advantage that the cooling medium in the cooling medium return can also cool the current conducting lead 11, which becomes very hot due to the high power required for welding.

Additional leads can be provided inside the hose assembly 1.
Figure 2 shows an additional embodiment of a hose assembly 20 according to the invention. The hose assembly 20 represented in Figure 2 has an essentially coaxial arrangement of the individuai elements. In the interior of the hose assembly 20, a welding wire 21 is guided inside a spiral wire guide 22. Encompassing the spiral wire guide 22, an intermediate space 23 is provided, which serves to convey the process gas.
A hose 24 is provided to create a gas-tight seal. The hose 24 is made of an elastic polymer. Current conducting leads 25 and control leads 26, shown here as black, are positioned on the hose 24. The current conducting leads 25 have the stranded wire configuration according to the invention, which will be specified in greater detail in reference to Figure 5. The hose assembly 20 is held together by an outer hose 27 that encompasses all the hoses. An annular channel is formed between outer hose 27 and hose 24 and holds the current conducting leads 25 and the other leads. The hose assembly 20 can be a part of a larger hose assembly in which additional hoses for various purposes are provided, for example cooling medium hoses and the like.
The current conducting leads 25 and 44 (Figure 5) are wound helically around the central channel 23 or 41 (Figure 5). The current conducting leads and stranded wires 25, 44, respectively, are thus arranged in the outer area of the cross section of the hose assembly. This measure allows the flexural stress on the current conducting leads 25, 44, especially in the areas of the smallest radius of curvature of the hose assembly, to be distributed and thus reduced.

Figure 3 shows an enlarged representation of the current/water cable 9 of Figure 1.

The current/water cable 9 comprises an outer hose 30, which is embodied as water-tight, allowing it to conduct the cooling medium. in place of water, any other fluid known in the prior art can be used as the cooling medium. In a concentric arrangement, the current conducting lead 11 is located at the center of the current/water cable 9.

The current conducting lead 11 is embodied as a stranded wire comprised of individuai wires 32. The individuai wires 32 of the stranded wire 11 are made of aluminum or an aluminum alloy. Pure aluminum having a degree of purity of A199 to A199.9 has proven particularly suitable for this purpose. These wires 32 are covered or coated with a layer of copper, thereby substantially reducing transition resistance. The thickness of the coating is between 1 and 100 pm.
The individual wires 32 have an Individual wire diameter of 0.1 to 0.3 mm.
Approximately thirty individual wires are bundled into a single stranded wire, wherein stranded wires containing up to 100 individual wires have proven suitable in terms of their elastic properties. The cross section of such a stranded wire is approximately 10 mm2, whereas the copper stranded wires known from the prior art have a cross section of 6 mm2, for example. With aluminum, cross sections of up to approximateiy 30 mmZ are easily possible. The length of lay of the stranded wires themselves is approximately 60 mm, but can range from 15 mm to 200 mm, depending upon the stranded wire cross section.

For so-called composite leads, copper-coated individual wires made of aluminum or an aluminum alloy and individual wires made of copper or a copper alloy can also be used in a stranded wire.

In a further embodiment which is not shown here, the current conducting lead 11 can have a plurality of stranded wires, wherein a core stranded wire is provided, around which the other stranded wires 31 are laid.

It is possible to provide a plurality of the current/water cables shown in Figure 3 inside a single hose assembly. Two current/water cables have proven particularly preferable, one being used for supplying cooling medium and one for returning cooling medium.
In this way it is possible to divide the current conducting leads, thereby increasing the flexibility of the hose assembly while improving the cooling power of the cooling medium on the current conducting leads. Assemblies of this type are known in the prior art.

Figure 4 shows a longitudinal section of a power cable 40 with a connection 35 to a base of the welding device. The connection 35 comprises a hexagon nut 36 for connecting the power cable 40 to the base in the proper alignment. A wire end sleeve 37 and a ferrule 38 are also provided, which accommodate the end of the lead 40.

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Also shown are control leads 43, which are connected to the base via separate plug connectors 39. The control leads 43 extend out of an outer sheath 46 of the power cable 40 in front of the end area of the power cable 40. In the interior of the hose 40, the crimped connection creates a hollow area 41 extending from the connection 35 to the opposite end of the lead 40, which is tightly sealed. The area 41 can be gas-tight and/or fluid-tight.

Figure 5 shows a cross section of the power cable along the section line A-A
of Figure 4 of the power cable 40, in the inside of which is the area 41, which can be used to conduct either a cooling medium or a process gas.

The inside area 41 is sealed off by a hose 42. On the outside of the hose 42 a plurality of leads having different functions are arranged. Control leads 43 for controlling the functions of the welding device are indicated by closely hatched lines.
Current conducting leads 44, which are also embodied as stranded wires, are indicated by lightly hatched lines. The areas 45 are assigned no specific function. The areas 45 can be filled with a filler material or with plastic cords, for example. The leads 43, 44 and the areas 45 are encompassed by a hose 46.

Figure 6 shows a perspective view of the current conducting lead 11 of Figures 1 and 4.
The individual wires 32 are laid around a core wire 47. One-half lay is shown here. The length of lay d, i.e., the length extending in the direction of conduction over which an individual wire 32 is wrapped once completely around the core lead 47, is 60 mm.
However, the length of lay can vary from 20 mm to 120 mm, depending upon the thickness of the lead 11 and the thickness of the individual wires 32. A lead embodied in this manner has the advantage that it can withstand many types of stress. The lead 11 can be twisted in both directions, bent and stretched or compressed. Moreover, the elasticity of a lead embodied in this manner is significantly greater than with a lead made of solid material having the same lead cross section.

List of Reference Symbols 1 - Hose assembly 2 - Outer hose 3- Cooling medium intake hose 4 - Process gas hose 5 - Spiral wire guide 6 - Welding wire 7 - Spiral wire guide 8 - Control lead 9 - Current/water cable 10 - Hose 11 - Current conducting lead 12 - Channel 20 - Hose assembly 21 - Welding wire 22 - Spiral wire guide 23 - Channel 24 - Hose 25 - Stranded wire 26 - Control lead 27 - Outer hose - Outer hose 32 - Individual wires 25 35 - Connection 36 - Hexagon nut 37 - Wire end sleeve 38 - Ferrule 39 - Plug connector 30 40 - Power cable 41 -Area 42-Hose 43 - Control leads 44 - Current conducting leads 45 - Area 46 - Hose 47 - Core wire d - Length of lay

Claims

1. Hose assembly (1) for an arc welding or cutting torch, having a plurality of current conducting leads (25, 44), wherein the leads (25, 44) comprise an aluminum wire, the current conducting leads (25, 44) are accommodated in a channel, and wherein the hose assembly (1) has a channel (5, 22) for guiding a welding wire (6, 21), characterized in that the current conducting leads (25, 44) are arranged coaxially around a central channel (23, 41) for conducting a medium, all the channels are arranged coaxially, the channel with the current conducting leads (25, 44) encompasses the channel (23, 41) for conducting the medium and the channel (23, 41) for conducting the medium encompasses the channel (22) for guiding the welding wire (6, 21), and the leads (25, 44) are equipped with an outer sheath made of a layer of copper.

2. Hose assembly of claim 1, characterized in that the layer of copper is 1 to 100 µm thick.

3. Hose assembly of claim 1 or 2, characterized In that the one lead (25, 44) has at least one stranded wire (11, 25, 44), the individual wires (32) of which consist of copper-coated aluminum wires.

4. Hose assembly of any one of the preceding claims, characterized in that the aluminum wire is made of aluminum or an aluminum alloy.

5. Hose assembly of any one of the preceding claims, characterized in that at least one composite lead (11, 25, 44) is provided, which contains individual wires (32) made of copper-coated aluminum or an aluminum containing alloy and individual wires made of copper or a copper containing alloy.

6. Hose assembly of any one of the preceding claims, characterized in that the current conducting lead (11, 25, 44) has at least four individual stranded wires, which are laid around a core stranded wire.

7. Hose assembly of claim 6, characterized in that each individual stranded wire (11, 25, 44) and/or the core stranded wire is comprised of at least 20 individual wires (32).

8. Hose assembly of any one of the preceding claims, characterized in that the individual wires (32) have a diameter of 0.05 mm to 0.5 mm, preferably 0.15 mm.

9. Hose assembly of any one of the preceding claims, characterized in that the current conducting leads (25, 44), especially the current conducting stranded wires, are laid spirally or helically around a central channel (22, 41).

10. Hose assembly of any one of the preceding claims, characterized in that the length of lay (d) of the stranded wires (11, 25, 44) ranges from 15 mm to 200 mm, preferably from 40 mm to 60 mm.

11. Hose assembly of any one of the preceding claims, characterized in that at least one additional control lead (8, 43) is provided.

12. Hose assembly of any one of the preceding claims, characterized in that at least two channels (3, 4, 12) are provided for conducting a medium, and at least two current conducting leads (25, 44) are provided.

13. Hose assembly of any one of the preceding claims, characterized in that the channels (12, 23) are separated from one another by a polymer.

14. Hose assembly of any one of the preceding claims, characterized in that the medium is a gas or a fluid.

15. Hose assembly of any one of the preceding claims, characterized in that the current conducting lead (9, 20, 25, 40, 44) has a connection (35) at one end, which is connected to the current conducting lead (9, 20, 25, 40, 44) via a crimped connection.

16. Hose assembly of any one of the preceding claims, characterized in that the current conducting lead (9, 20, 25, 44) is welded to a connection (35) or a wire end sleeve (37) via ultrasound.