JP7323269B2 - cable - Google Patents

Description

The present invention relates to cables.

Patent Document 1 describes a power supply cable for a robot welder as follows. The cable is formed by twisting two insulated core wires coated with heat-resistant rubber on a composite stranded conductor, and forming a circular shape by filling a recess formed in the circumference of the twisted insulated core wire with inclusions, A tape is wound around the outer circumference, and a shield braid is further applied. An inner sheath is covered with a flexible thermoplastic resin on the circumference of the shield braid, and an outer sheath is covered with a thermoplastic urethane elastomer on the outer circumference.

Japanese Utility Model Laid-Open No. 64-20981

BACKGROUND ART When arc welding is performed on an arc welding line using a robot welder or the like, a sensor (position detection sensor) detects the position of a movable object to be welded (workpiece) on the welding line. The position detection sensor transmits detection information to the controller of the welder via a cable. Based on the detection information from the position detection sensor, the welding arm of the robot welder performs arc welding on the workpiece. At this time, particles (spatter) scattered during arc welding may hit the cable, and the heat may damage the outer covering of the cable.
Therefore, the cable connected to the position detection sensor used in the conventional robot welder had to be replaced within several months.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a cable that can be used for a long period of time as a cable that is connected to a position detection sensor or the like used in a robot welder or the like, and that is superior in heat resistance to conventional cables.

A cable according to one aspect of the present invention comprises:
(1) A cable having a plurality of insulated wires and a jacket covering the plurality of insulated wires,
The jacket has three layers, an inner layer, a metal layer and an outer layer, in order from the inside,
The cable, wherein the outer layer is a fluororesin.

According to the above, even when used in connection with a position detection sensor used in a robot welder, damage due to the heat of spatter scattered during arc welding can be reduced, and it has excellent heat resistance and can be used for a long time. be possible.

1 is a schematic cross-sectional view of a cable according to one aspect of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a robot welder that is an example of a usage pattern of a cable according to one aspect of the present invention;

[Description of the embodiment of the present invention]
First, the contents of the embodiments of the present invention will be described.
A cable according to one aspect of the present invention comprises:
(1) A cable having a plurality of insulated wires and a jacket covering the plurality of insulated wires,
The jacket has three layers, an inner layer, a metal layer and an outer layer, in order from the inside,
The cable, wherein the outer layer is a fluororesin.
According to this configuration, even when used in connection with a position detection sensor or the like used in a robot welder, it is possible to reduce damage due to the heat of spatter scattered during arc welding.

(2) Preferably, the metal layer is a metal braid.
(3) The density of the metal braid is preferably 91% or more and 97% or less.
(4) The inner layer is preferably made of fluororesin.
(5) At least one of the outer layer and the inner layer is preferably crosslinked.
According to the configurations (2) to (5) above, the heat resistance and strength are further increased, and damage due to the heat of spatter scattered during arc welding can be further reduced.

(6) At least one of the outer layer and the inner layer is preferably made of fluororubber.
According to this configuration, flexibility is improved, wiring work can be facilitated, and it is also advantageous when connecting to the movable portion.
(7) It is preferable that the outer layer and the inner layer have different colors.
With this configuration, it becomes easier to determine the degree of damage/deterioration and the timing of replacement.
(8) It is preferable that the inner layer is formed by extrusion molding.
According to this configuration, the work of forming the inner layer is facilitated, and the inner layer is filled between the insulated wire and the metal layer without any gap, so that the heat resistance and the strength can be further improved.
(9) It is preferable that the ratio of the average thickness of the outer layer to the average thickness of the inner layer is 1.90 or more and 3.54 or less.
It is presumed that this configuration can optimize the balance between heat resistance and flexibility.

[Details of the embodiment of the present invention]
Hereinafter, specific examples of cables according to embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing the outline of the cable of this embodiment. The cable 1 has two insulated wires 2 and a jacket 3 covering the two insulated wires 2 . The jacket 3 has three layers, an inner layer 31, a metal layer 32 and an outer layer 33, in order from the inside.

(Insulated wire)
The insulated wire 2 is formed by covering a conductor 21 with an insulating resin layer 22 .
The material of the conductor 21 is not particularly limited as long as it has the necessary conductivity, and examples thereof include copper wire (unplated or plated), copper alloy wire, copper-plated steel wire, and the like. Among them, an annealed copper wire and a copper alloy wire are preferable. Moreover, it is preferable that the conductor 21 is a twisted wire.
The cross-sectional area of the conductor 21 is not particularly limited, but is preferably 0.08 mm ² or more and 5 mm ² or less, more preferably 0.2 mm ² or more and 2.5 mm ^{2 or} less. The outer diameter of the conductor 21 is not particularly limited, but is preferably 0.38 mm or more and 3 mm or less, and more preferably 0.55 mm or more and 1.9 mm or less.

The resin constituting the insulating resin layer 22 of the insulated wire 2 is not particularly limited, but examples thereof include fluororesin and silicone resin. Among these, fluororesins are preferred from the viewpoint of high heat resistance.
The details of the fluororesin used for the insulating resin layer 22 are as described later.
Although the thickness of the insulating resin layer 22 is not particularly limited, it is preferably 0.05 mm or more and 1 mm or less, and more preferably 0.1 mm or more and 1.4 mm or less. The outer diameter of the insulating resin layer 22 is not particularly limited, but is preferably 0.48 mm or more and 5 mm or less, more preferably 0.8 mm or more and 3 mm or less.
The insulating resin layer 22 is preferably formed by extrusion molding.

Although two insulated wires 2 are used in the cable 1 of FIG. 1, the cable according to one aspect of the present invention is not limited to two insulated wires, and may have three or more insulated wires. However, it is preferably two or more and three or less.
In the cable 1, the two insulated wires 2 may be twisted together or may be parallel wires, but twisted wires are preferred. When it is twisted, the twist pitch is not particularly limited, but is preferably 10 mm or more, preferably 17 mm or more.

(outer cover)
An inner layer 31 forming the jacket 3 is present on the outside of the two insulated wires 2 .
Although the thickness of the inner layer 31 is not particularly limited, it is preferably 0.1 mm or more and 1 mm or less, and more preferably 0.15 mm or more and 0.6 mm or less. The outer diameter of the inner layer 31 is not particularly limited, but is preferably 1.16 mm or more and 12.0 mm or less, more preferably 1.9 mm or more and 7.2 mm or less.
The inner layer 31 is made of resin. The resin that constitutes the inner layer 31 is not particularly limited, but includes fluororesin, silicone resin, and the like. Among these, fluororesins are preferred from the viewpoint of high heat resistance.
The details of the fluororesin used for the inner layer 31 are as described later.
Formation of the inner layer 31 is not particularly limited, but includes extrusion molding, insertion of the insulated wire 2 into a tube-shaped material, winding of a tape-shaped material around the insulated wire 2, and the like. Among these, the work of forming the inner layer 31 is facilitated, and the heat resistance and strength of the cable 1 are further improved by filling the inner layer 31 without gaps between the insulated wire 2 and the metal layer 32 described later. From this point of view, extrusion molding is preferred.

Outside the inner layer 31 is a metal layer 32 that constitutes the jacket 3 .
The presence of the metal layer 32 can improve the heat resistance of the cable 1 .
Although the thickness of the metal layer 32 is not particularly limited, it is preferably 0.05 mm or more and 1 mm or less, and more preferably 0.1 mm or more and 0.4 mm or less. The outer diameter of the metal layer 32 is not particularly limited, but is preferably 1.26 mm or more and 14.0 mm or less, more preferably 1.36 mm or more and 12.8 mm or less.
Metal species constituting the metal layer 32 are not particularly limited, but examples thereof include iron, copper, aluminum, and stainless steel. Among them, iron or copper is preferable from the viewpoint of high heat resistance (high melting point).
The form of the metal layer 32 is not particularly limited, but examples thereof include metal braid, horizontal winding, and plate winding. Among them, metal braid is preferable.

When a metal braid is used as the metal layer 32, the braid density is preferably higher than that of a normal cable. preferable.
The density (γ) of the metal braid is defined by the following formula.

In the above formula, the number of strokes C means the number of groups of metal wires in the braid, and the number of strokes N per stroke means the number of metal wires in one group in the braid.

Outside the metal layer 32 is an outer layer 33 that constitutes the jacket 3 .
Since the outer layer 33 is made of fluororesin, the cable 1 can have the required heat resistance.

Although the thickness of the outer layer 33 is not particularly limited, it is preferably 0.3 mm or more and 2 mm or less, and more preferably 0.5 mm or less and 1.4 mm or more. The outer diameter of the outer layer 33 is not particularly limited, but is preferably 1.01 mm or more and 20 mm or less, more preferably 3.0 mm or more and 12 mm or less. Outer layer 33 is preferably formed by extrusion.
The details of the fluororesin forming the outer layer 33 will be described later.

In the cable 1 shown in FIG. 1, the jacket 3 is composed of three layers, the inner layer 31, the metal layer 32 and the outer layer 33, but may have additional layers as necessary. good.

The fluororesin used for the insulating resin layer 22, the inner layer 31, and the outer layer 33 is not particularly limited, but is preferably crosslinked from the viewpoint of further improving the heat resistance and strength of the cable 1. When forming a crosslinked fluororesin, it is crosslinked after providing a resin layer by extrusion molding. The cross-linking method may be thermal cross-linking or electron beam cross-linking, but electron beam cross-linking is preferred.
As the fluororesin, fluororubber is preferable from the viewpoints of excellent flexibility and facilitating wiring work and from the viewpoint that it can be used for connection to a movable part.

In the cable 1 of the present embodiment, the ratio of the average thickness of the outer layer 33 to the average thickness of the inner layer 31 is 1.90 or more and 3.54 or less from the viewpoint of optimizing the balance between heat resistance and flexibility. It is preferably 2.30 or more and 3.10 or less. The average thickness of the inner layer 31 is defined as half the difference between the outer diameter of the inner layer 31 and the maximum cross-sectional length of two insulated wires twisted or bundled.

The cable 1 of this embodiment is preferably used for wiring of a robot welder or the like.
A schematic of a robot welder in which the cable 1 is used is shown in FIG.
(welding machine)
The robot welder 100 shown in FIG. 2 has a welding arm 110 , a controller 120 and an active work line 130 . Welding arm 110 and controller 120 are connected by a power supply/control cable 140 . A large number of position detection sensors 150 are arranged on the work line 130 . A position detection sensor 150 detects the position of an object to be welded (work) 200 on the work line 130 . A sensor cable 160 is connected to the position detection sensor 150 . Position information of the work 200 on the work line 130 detected by the position detection sensor 150 is transmitted to the controller 120 via the sensor cable 160 .
Cable 1 is preferably used mainly as sensor cable 160 of robot welder 100 , but may be used as power supply/control cable 140 .

When the cable 1 of the present embodiment is used as the sensor cable 160 of the robot welder 100, it is preferable that the outer layer 33 and the inner layer 31 have different colors. In this case, when the cable 1 is damaged during use, it is possible to easily determine the replacement timing.
For example, it is preferable to color the inner layer 31 by adding an orange pigment or the like to the resin forming the inner layer 31 .
When the cable 1 is used as the sensor cable 160 of the robot welder 100, the surface of the outer layer 33 of the cable 1 is blackened by spatter scattered during welding. Then, with continued use, the outer layer 33 and the metal layer 32 become perforated. When the holes opened in the outer layer 33 and the metal layer 32 reach the inner layer 31, the bright orange color of the inner layer 31 appears in contrast to the surface of the outer layer 33 which is stained black. The timing at which the inner layer 31 becomes orange or the like can be determined as the timing for replacement of the cable 1 .

Hereinafter, the results of evaluation tests using examples and comparative examples according to the present invention will be shown, and the present invention will be described in more detail. However, the present invention is not limited to these examples.

[Preparation of Cable for Example]
A cable 1 having the form shown in FIG. 1 was produced. Specific specifications are as follows.
Two insulated wires 2 were used.
As the conductor 21 of each insulated wire 2, an annealed copper stranded wire having a cross-sectional area of 0.3 mm ² and an outer diameter of 0.72 mm was used.
The insulating resin layer 22 of the insulated wire 2 is formed by extruding a fluororubber to provide a resin layer and then cross-linking the layer by electron beam irradiation. The insulating resin layer 22 has a thickness of 0.2 mm and an outer diameter of 1.12 mm.
The two insulated wires 2 are twisted at a twist pitch of 25.

The inner layer 31 on the outside of the two insulated wires 2 was formed by extruding a fluororubber to provide a resin layer, followed by cross-linking by electron beam irradiation. The inner layer 31 had an average thickness of 0.25 mm and an outer diameter of 3.44 mm. The inner layer 31 was colored orange by containing a pigment orange pigment in an amount of 5 wt % with respect to the resin component.
Metal braid having a thickness of 0.7 mm was used for the metal layer 32 outside the inner layer 31 . An annealed copper wire having a wire diameter d of 0.14 mm was used as the wire of the metal braid. The number of strokes N is 6, the number of strokes C is 16, the angle α of the wire with respect to the vertical axis of the wire is 71.6 degrees, the pitch P of the braid is 28.6 mm, the diameter D under the braid is 3.44 mm, The braid density (γ) was 93.6%.
The outer layer 33 on the outside of the metal layer 32 was formed by extruding a fluororubber to provide a resin layer, followed by cross-linking by electron beam irradiation. The outer layer 33 had an average thickness of 0.68 mm and an outer diameter of 4.8 mm.

[Production of cable for comparative example]
Except that a polyvinyl chloride (PVC) layer of the same thickness was formed by extrusion instead of the inner layer 31, and a silicone tube with a thickness of 1.38 mm was used instead of the metal layer 32 and the outer layer 33. A cable for the comparative example was produced in the same manner as the cable for the comparative example.

[Test using actual equipment]
Welding work was carried out by using the prepared cable for example and cable for comparative example as the sensor cable 160 of the robot welding machine 100 shown in FIG. Welding work was continuously performed under the same working conditions, and the appearance of each cable was observed after two months. As a result, no damage was observed on the outer layer of the cable for Example. On the other hand, many damaged holes were observed in the silicone tube of the comparative cable.

1: Cable 2: Insulated wire 21: Conductor 22: Insulating resin layer 3: Jacket 31: Inner layer 32: Metal layer 33: Outer layer 100: Robot welding machine 110: Welding arm 120: Controller 130: Work line 140: Power supply/ Control cable 150: Position detection sensor 160: Sensor cable 200: Object to be welded (workpiece)

Claims (6)

A cable having a plurality of insulated wires and a jacket covering the plurality of insulated wires,
The cable is configured by twisting the plurality of insulated wires together,
A conductor cross-sectional area of the insulated wire is 0.2 mm ² or more and 5 mm ² or less,
The jacket has three layers, an inner layer, a metal layer and an outer layer, in order from the inside,
The outer layer is a fluororesin,
The outer layer has a thickness of 0.3 mm or more and 2.0 mm or less,
The inner layer contains a pigment and is colored so that the outer layer and the inner layer have different colors,
The metal layer is a metal braid and has a thickness of 0.1 mm or more and 1 mm or less ,
The metal braid has a density of 91% or more and 97% or less,
cable. The cable according to claim 1, wherein said inner layer is fluororesin. 3. Cable according to claim 1 or claim 2, wherein at least one of the outer layer and the inner layer is crosslinked. The cable according to any one of claims 1 to 3, wherein at least one of the outer layer and the inner layer is made of fluororubber. The cable according to any one of claims 1 to 4, wherein the inner layer is formed by extrusion molding. The cable according to any one of claims 1 to 5, wherein the ratio of the average thickness of the outer layer to the average thickness of the inner layer is 1.90 or more and 3.54 or less.

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