WO2018221793A1 - Cable for robot - Google Patents

Abstract

The present invention relates to a cable for a robot. A cable for a robot according to the present invention comprises: a center insert; at least one inner core which surrounds the center insert; at least one first insert which surrounds the center insert and is disposed between the inner cores; an inner binding tape which surrounds and binds the inner core and the first insert, and is made of an unsintered fluoride resin; at least one outer core which surrounds the outside of the inner binding tape; at least one second insert which is disposed outside the inner binding tape; an outer binding tape which binds the outer core and the second insert, and is made of an unsintered fluoride resin; a shielding layer disposed outside the outer binding tape; and a sheath disposed outside the shielding layer.

Description

Robot Cable

The present invention relates to a cable for a robot, and more particularly, to a cable for a robot that dramatically improves durability against bending and bending life so as to be used in an industrial robot.

In general, industrial robots perform various operations such as welding, painting, and conveying in a machine parts production line. The industrial robot is connected to a central control unit by a robot cable, and receives the necessary power through the robot cable, and also transmits and receives information necessary for various tasks.

However, in this process, the industrial robot is continuously moved or moved, and thus a fatigue load such as repeated tension, torsion, bending, etc. is applied to the robot cable connected to the industrial robot.

In this case, disconnection of the conductor of the robot cable may occur, and when the production line is stopped due to the disconnection, considerable time and cost loss for cable replacement occurs. Therefore, there is a need for a cable for a robot that ensures high durability.

In order to solve the above problems, an object of the present invention is to provide a robot cable that can significantly increase durability and fatigue life even when used in an environment in which torsion or bending frequently occurs.

In order to solve the said subject, this invention is centered; At least one inner core surrounding the central interposition; At least one first interposition surrounding the central interposition and disposed between the inner cores; An inner binding tape surrounding and enclosing the inner core and the first interposition and made of an unsintered fluorine resin; At least one outer core surrounding an outer side of the inner binding tape; At least one second interposition provided on an outer side of the inner binding tape; An outer binding tape which binds the outer core and the second interposition and is made of an unsintered fluororesin; A shielding layer provided on an outer side of the outer binding tape; And, sheath provided on the outside of the shielding layer; it can provide a cable for a robot comprising a.

In this case, the inner core includes a first conductor having a plurality of first wires twisted at a predetermined first pitch, and a first insulating layer provided on an outer side of the first conductor, wherein the first pitch is the first conductor. It may correspond to 15 to 30 times the outer diameter of one conductor.

The outer core may include a second conductor in which a plurality of second wires are twisted at a predetermined second pitch, a core part in which the plurality of second conductors are twisted in a predetermined third pitch, and an outer side of the core part. And a second insulating layer, wherein the second pitch may correspond to 15 to 50 times the outer diameter of the second conductor, and the third pitch may correspond to 10 times to 30 times the outer diameter of the core portion. .

In addition, the first wire rod and the second wire rod of the inner core and the outer core may have a yield strength increase rate of 1% to 30%.

In addition, the unsintered fluororesin may be made of unsintered polytetrafluoroethylene (PTFE) resin.

Here, the inner binding tape and the outer binding tape may have a coefficient of friction between 0.05 and 0.2.

In addition, the first interposition and the second interposition may have outer diameters corresponding to outer diameters of the inner core and the outer core, respectively.

Here, the outer diameter of the first interposition and the second interposition may have an outer diameter of 80% to 120% compared to the outer diameter of the inner core and the outer core.

In this case, at least one of the center interposition, the first interposition, and the second interposition may be formed by twisting an elastic yarn.

And, the elastic yarn may be composed of a polyester yarn (polyester yarn).

In addition, an additional binding tape may be further provided between the shielding layer and the sheath.

In this case, the additional binding tape may be made of unsintered polytetrafluoroethylene (PTFE) resin.

In this case, the sheath may be formed by tube type extrusion.

In addition, in order to solve the above problems, the present invention is a plurality of inner cores disposed on the outer peripheral surface of the center interposition of the circular cross section; An inner binding tape for binding the outer core; A plurality of outer cores disposed on an outer circumferential surface of the inner binding tape; An outer binding tape for binding the outer core; A shielding layer provided on an outer side of the outer binding tape; And a sheath provided on an outer side of the shielding layer, wherein the inner binding tape and the outer binding tape are provided with an unsintered fluorocarbon resin having a coefficient of friction between 0.05 and 0.2. can do.

According to the robot cable according to the present invention, even when used in an environment in which torsion or bending frequently occurs, durability, fatigue life can be significantly increased.

In addition, according to the cable for a robot according to the present invention, the durability is improved, it is possible to minimize the process interruption in the industrial site, it is possible to minimize the loss due to the process interruption.

1 is a cross-sectional view showing an internal configuration of a cable for a robot according to an embodiment of the present invention,

2 and 3 are graphs showing the resistance change rate according to the number of twists of the examples and the comparative example according to the present invention;

Figure 4 is a graph comparing the difference in the coefficient of friction when the binding tape and the conventional binding tape according to the present invention,

5 is a graph comparing the change of the pull-out force of the embodiment and the comparative example according to the present invention,

6 is a graph showing the resistance change rate (%) according to the number of twists of the examples and comparative examples according to the present invention.

Hereinafter, a robot cable according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing the internal configuration of the robot cable 100 according to an embodiment of the present invention.

Referring to FIG. 1, the robot cable 100 includes a center interposition 20, at least one inner core 10 surrounding the center interposition 20, and the inner core surrounding the center interposition 20. An inner binding tape comprising at least one first intervening member 22 disposed between the first intervening member 22 and the inner core 10 and the first intervening member 22 to bind and bind to an unsintered fluorocarbon resin. 30, at least one outer core 40 surrounding the outer side of the inner binding tape 30, at least one second interposition 50 provided on the outer side of the inner binding tape 30, the outer core An external binding tape 32 made of an unsintered fluorine resin, a shielding layer 60 provided on an outer side of the outer binding tape 32, and the shielding, which binds the 40 and the second interposition 50. Sheath 70 is provided on the outside of layer 60.

In the robot cable 100, the inner core 10 may be configured for communication with the outside, and the outer core 40 may be configured for power supplying power.

Specifically, the inner core 10 includes a first conductor 13 having a plurality of first wires 12 twisted at a predetermined first pitch, and an outer side of the first conductor 13. The first insulating layer 14 is provided.

The first wire 12 may be made of a material such as copper, and the first insulating layer 140 covering the first conductor 13 formed of the first wire 12 may include polyethylene (PE, Polyethylene) or high density polyethylene (HDPE).

However, when the first wire 12 is subjected to the above-described process to form the inner core 10, tensile stress may remain in the first wire 12. As such, when tensile stress remains in the first wire 12 after the inner core 10 is formed, it means that the tensile pre-strain is high, in which case the first wire 12 The yield strength of can be increased, for example 30% or more.

As such, when the yield strength of the first wire rod 12 is increased, the fatigue life of the first wire rod 12 is reduced, and damage such as cracks occurs in the first wire rod 12. Done. The damage of the first wire 12 may be represented by a change rate (%) of changing the resistance.

That is, the relatively high resistance change rate (%) means that a lot of damages such as cracks occur in the first wire 12, and in severe cases, disconnection may occur.

Figure 2 is a graph showing the resistance change rate according to the number of twists of the Examples and Comparative Examples according to the present invention. The embodiment refers to a wire rod having an increase rate of yield strength of 1% to 30% after the inner core 10 is formed, and the comparative example shows an increase rate of yield strength after forming the inner core 10. This means more than 30% wire rod. In the graph of FIG. 2, the horizontal axis represents the number of twists (× 1000 times), and the vertical axis represents the change rate (%) of the resistance.

As shown in FIG. 2, in the case of the embodiment, even when the number of twists exceeds 10,000, the resistance change rate corresponds to approximately 7%, indicating that the resistance change rate is very small. It can be seen that the case of the wire rod of the embodiment is relatively very little damage, such as cracks, which is also relatively small preform deformation in the wire rod of the embodiment, the increase rate of yield strength is less than 30%, that is, 1% to 30% It can be seen that.

On the other hand, in the comparative example, if the number of twists exceeds 10,000, the resistance change rate corresponds to approximately 13% or more, and thus the resistance change rate is relatively large. It can be seen that the wire rod of the comparative example has a relatively very high damage such as cracks, which can also be seen that the increase in the yield strength exceeded 30% due to the relatively high deformation strain in the wire of the comparative example.

Therefore, it can be seen that the fatigue life is longer as the preform deformation is relatively smaller after the wire is processed, and the fatigue life can be predicted indirectly through the increase rate of yield strength or the resistance change rate after the wire is processed.

Therefore, the fatigue life can be increased by setting the rate of increase in yield strength or the rate of change in resistance after processing the wire rod in accordance with a predetermined threshold. For example, in the present invention, after the wire is processed, the case where the increase rate of yield strength is 1% to 30%, that is, 30% or less, or the resistance change rate is 1% to 25%, that is, 25% or less is set as a threshold. Can be.

The present inventors conducted an experiment to confirm the factors affecting the resistance change rate of the wire rod, Figure 3 shows the results.

Figure 3 is a graph showing the resistance change rate according to the number of twists of the examples and comparative examples according to the present invention. This embodiment forms a wire rod after the plurality of wire rods are twisted to a predetermined pitch ('assembly type'), and the cores are twisted again at a predetermined pitch ('composite type'). The comparative examples refer to a case where a plurality of wire rods are twisted at a predetermined pitch to form a conductor ('assembly type'). In the case of the Comparative Example and Example, the entire outer diameter is formed to be the same.

At this time, Comparative Example 1 is formed such that the pitch of the wire rod is relatively larger than Big Bridge Example 2. For example, in Comparative Example 1, the pitch of the wire rod corresponds to approximately 18 mm, and in Comparative Example 2, the pitch of the wire rod corresponds to approximately 12 mm. In the graph of FIG. 3, the horizontal axis represents the number of twists (× 1000 times), and the vertical axis represents the change rate (%) of the resistance.

As shown in FIG. 3, it can be seen that the resistance change rate (%) according to the increase in the number of torsions of the wire rods of the embodiment after processing through the aggregate type and the composite type is significantly superior to the comparative examples.

That is, in the case of the wire rod of the above embodiment, even when the number of twists exceeds 10,000, the resistance change rate (%) corresponds to about 12%, which is very small.

On the other hand, in the case of the wire rod of Comparative Example 2 that passed only the aggregate type, it can be seen that the resistance change rate (%) exceeds approximately 25% when the number of twists exceeds 2,000 times.

Meanwhile, in the case of the wire rod of Comparative Example 1, the resistance change rate (%) corresponds to approximately 23% when the number of twists exceeds 10,000 times, which is superior to Comparative Example 2, but is higher than that of Example. You can see that this is bigger.

As a result, when the wire rod is processed, it can be seen that the resistance change rate is relatively small when both the aggregate type and the complex type are passed. In addition, in the case of only the aggregate type, the larger the pitch of the wire rod, the smaller the resistance change rate.

As shown in FIG. 1, the first conductor 13 of the inner core 10 may be formed in an aggregate type. In this case, the first pitch of the first wire 12 may correspond to 15 to 30 times the outer diameter of the first conductor 13. When less than 15 times as described above, the change rate of the resistance of the first wire 12 exceeds 25%, or the increase rate of yield strength exceeds 30%. On the other hand, if it is larger than 30 times as described above, the pitch becomes too long to prevent the first conductor 13 from being properly formed in a circular shape.

That is, when the first pitch of the first wire 12 is in the above-described range, the yield strength increase rate of the first wire 12 of the inner core 10 corresponds to 1% to 30%, and the resistance The percent change corresponds to 1% to 25%.

On the other hand, the center portion 20 of the inner core 10 is provided with a center interposition (20). The central interposition 20 serves to maintain the circular shape of the cable 100 for the robot together with the first intervening 22 and the second interposition 50 to be described later.

In the case of the conventional cable, the intervening cable includes a PVC string, polyethylene (PE), and ethylene propylene diene monomer (EPDM).

In the case of a conventional cable, when bending or torsion is applied to the cable, a friction occurs, not slip, between the insulator and the interposition of the core, and at this time, more stress is applied to the core to the conductor. Damage or disconnection will occur.

Table 1 below shows the results of measuring the resistance of the inner core 10 after 500,000 torsion tests of the examples and the comparative examples having the same structure. The above embodiment refers to a case in which the center interposition 20, the first interposition 22, and the second interposition 50 are formed by twisting an elastic yarn made of a polyester yarn. The example shows the case formed with EPDM. The inner cores 1 to 5 correspond to arbitrary numbers of the inner cores 10 shown in FIG.

Comparative Example Resistance (mΩ) Example Resistance (mΩ) Internal Core 1 18.27 7.1 Internal Core 2 18.05 7.6 Internal Core 3 37.5 8.2 Internal Core 4 16.06 7.1 Internal Core 5 28.07 7.5

In Table 1, the threshold is variable depending on the place where the cable is installed, the work process, the customer's request, etc., but corresponds to approximately 8.25 mΩ.

In this case, in the case of the comparative example, it can be seen that the resistance values of all the internal cores have a value greater than or equal to a threshold value and thus do not satisfy the reference value.

On the other hand, in the case of the above embodiment it can be seen that the maximum resistance value corresponds to 8.2 mΩ, all satisfy the reference value. In the case of the embodiment, the interposition is composed of a highly elastic yarn (yarn), even when the torsion and the like acts to deliver a relatively small stress to the inner core to prevent the increase in resistance due to damage of the internal stress.

Therefore, in the present invention, at least one of the center interposition 20, the first interposition 22, and the second interposition 50 may be formed by twisting an elastic yarn, wherein the elastic yarn is a polyester yarn. It may be made of (polyester yarn).

As shown in FIG. 1, the center interposition 20 is positioned at the center, and at least one inner core 10 and the first interposition 22 are disposed along the outer side of the center interposition 20.

In the drawing, the number of the inner cores 10 is shown as five and the number of the first intervening 22 is shown as three, but this is only an example and may be appropriately modified.

On the other hand, since the inner core 10 and the first interposition 22 together form a circular shape, the first interposition 22 preferably has an outer diameter corresponding to the outer diameter of the inner core 10, respectively.

Since the outer diameter of the inner core 10 may be determined according to the working environment to which the robot cable 100 is applied, determining the outer diameter of the first intervening 22 to correspond to the outer diameter of the inner core 10. It is preferable.

For example, the outer diameter of the first intervening 22 may have an outer diameter of 80% to 120% compared to the outer diameter of the inner core 10.

If the outer diameter of the first intervening 22 is too large, pressure may be applied to the inner core 10 during the torsion, so that damage such as disconnection may occur in the first conductor 13 of the inner core 10. have. In addition, when the outer diameter of the first intervening 22 is relatively small, it will not be able to achieve a circular shape.

On the other hand, the inner binding tape 30 is bound to surround the inner core 10 and the first interposition 22 and to serve to maintain a circular shape.

In the conventional cable, a nonwoven fabric or a sintered fluororesin is used as the binding tape. However, in the case of the sintered fluororesin, the strength and the friction coefficient are relatively high, and thus the stress is not absorbed when the twist or the like acts on the cable and the stress is transferred to the internal core. In addition, when a twist or the like acts on the cable, the inner core may be damaged by friction between the binding tape and the inner core.

Therefore, in the present invention, the inner binding tape 30 may be made of an unsintered fluorine resin having a relatively low friction coefficient and strong lubricity.

For example, the unsintered fluororesin may be made of unsintered polytetrafluoroethylene (PTFE) resin. At this time, it was confirmed that the inner binding tape 30 can be configured to have a coefficient of friction between 0.05 and 0.2. The binding tape 30 having such a friction coefficient enables smooth slippage when twisting the cable, thereby minimizing frictional damage between the binding tape and the outer core 40, thereby greatly improving the durability of the cable.

Figure 4 is a graph comparing the difference in the coefficient of friction when the binding tape (B) and the conventional binding tape (A) according to the present invention.

In FIG. 4, the binding tape (B) according to the present invention represents a case composed of an unsintered PTFE (Unsintered Polytetrafluoroethylene) resin.

As shown in FIG. 4, in the case of applying the conventional binding tape (A), the coefficient of friction corresponds to approximately 0.146 μ, whereas the binding tape B according to the present invention corresponds to 0.092 μ and has a coefficient of friction of approximately 37%. It can be seen that the reduction of.

On the other hand, Figure 5 is a graph comparing the change of the pull-out force (N) of the embodiment and the comparative example according to the present invention.

In FIG. 5, the embodiment shows a case in which the internal binding tape 30 is formed of an unsintered polytetrafluoroethylene (PTFE) resin, and the comparative example shows a case in which a sintered fluororesin is used as the binding tape. In addition, the pull-out force is defined as the force (N) required by friction with the outer core when the inner core is pulled out. In other words, the larger the pull-out force, the larger the friction force between the inner core and the outer core by the inner binding tape 30. On the contrary, the pull-out force is relatively smaller by the inner binding tape 30. This means that the friction between the inner and outer cores is small. In FIG. 5, the horizontal axis shows the length (mm) from which the inner core is pulled out, and the vertical axis shows the required force (N).

Looking at Figure 5, in the case of the comparative example it can be seen that the force required to decrease as the length to extract the inner core is increased. For example, it can be seen that the force required when the length of the inner core is extracted is approximately 100mm corresponds to approximately 30 to 35N.

On the other hand, in the case of the embodiment it can be seen that the force required relatively less than the comparative example. For example, the force required when the length of the inner core is about 100 mm corresponds to about 15 N, indicating that the force of about 50% to 57% is reduced compared to the comparative example.

In the case of the mobile power communication cable 100 according to the present invention, because the twisting, bending, etc. are frequently operated due to frequent movement, the smaller the pull-out force, the smaller the pull-out force between the inner core and the outer core. It can be seen that the friction is small, which is advantageous for durability and fatigue life.

Meanwhile, referring to FIG. 1, at least one outer core 40 and at least one second interposition 50 are provided on the outer side of the inner binding tape 30.

At this time, the outer core 40 may be formed by the above-described assembly and complex type processing.

For example, the outer core 40 may include a second conductor 43 in which a plurality of second wires 42 are twisted to a predetermined second pitch, and a third in which the plurality of second conductors 43 is predetermined. A core portion 45 twisted to a pitch and a second insulating layer 44 provided on the outer side of the core portion 45 may be provided.

In this case, the second pitch corresponds to 15 times to 50 times the outer diameter of the second conductor 43, and the third pitch corresponds to 10 times to 30 times the outer diameter of the core part 45.

In addition, when the second pitch and the third pitch of the second wire 42 fall within the above-mentioned range, the yield strength increase rate of the second wire 42 of the outer core 40 is increased from 1% to 30%. Correspondingly, the resistance change rate (%) corresponds to 1% to 25%.

On the other hand, the second interposition 50 has an outer diameter corresponding to the outer diameter of the outer core 40, for example, the outer diameter of the second interposition 50 is 80 compared to the outer diameter of the outer core 40 It may have an outer diameter of% to 120%.

In addition, the second interposition 50 may be formed by twisting elastic yarns, and the elastic yarns may be made of polyester yarns.

Since the description of the second interposition 50 is similar to the description of the first intervening 22 described above, repeated description thereof will be omitted.

In the drawing, the number of the outer cores 40 is shown as eight and the number of the second interpositions 50 is shown as one, but this is only one example and may be appropriately modified.

On the other hand, the outer binding tape 32 binds the outer core 40 and the second interposition 50, and is made of an unsintered fluorine resin. In this case, the unsintered fluorine resin may be made of unsintered polytetrafluoroethylene (PTFE) resin, and the outer binding tape 32 may have a coefficient of friction between 0.05 and 0.2.

Since the description of the outer binding tape 32 is similar to the description of the inner binding tape 30 described above, repeated description thereof will be omitted.

A shielding layer 60 is provided on the outer side of the outer binding tape 32. The shielding layer 60 may be formed of a metal tape or a metal braid by applying a material such as copper, aluminum, a copper alloy, or an aluminum alloy. The shielding layer 60 maintains the communication characteristics of the communication cable by electromagnetic shielding, or functions to protect the cable from an external shock.

On the other hand, the sheath 70 is provided outside the shielding layer 60. It is responsible for the outermost layer of the mobile power communication cable 100 of the sheath 70, and does not expose the above-described internal components to the outside and serves to protect the internal components from external impact.

In this case, in the case of the conventional cable, when the sheath is extruded, it is faithfully extruded and molded, but this method involves a problem of pressing marks caused by the sheath on the inner conductor or shielding layer after extrusion.

Therefore, in the present invention, when the sheath 70 is extruded, it is molded by tube type extrusion. Extrusion is performed by inserting the internal components into the sheath 70 while the sheath 70 is prepared in the form of a tube in advance, and after the extrusion, pressing marks caused by the sheath are generated in the conductor or shielding layer. You can prevent it.

Meanwhile, as illustrated in FIG. 1, an additional binding tape 34 may be further provided between the shielding layer 60 and the sheath 70. By providing the additional binding tape 34, the internal frictional force may be further reduced when torsion or bending acts on the cable 100 for the robot.

At this time, the additional binding tape 34 is made of unsintered PTFE (Unsintered Polytetrafluoroethylene) resin, and has a coefficient of friction between 0.05 and 0.2. Since the description of the additional binding tape 34 is similar to that of the inner binding tape 30 and the outer binding tape 32 described above, repeated description thereof will be omitted.

6 is a graph showing the resistance change rate (%) according to the number of twists of the examples and comparative examples according to the present invention.

In FIG. 6, the embodiment corresponds to the cable having the configuration of FIG. 1 described above, and the comparative example applies high density polyethylene (HDPE) or EPDM as an intervening device, and applies sintered fluorine resin with a binding tape. The case where was formed by faithful extrusion is shown. In Figure 6, the horizontal axis shows the number of twists (x1000 times), and the vertical axis shows the resistance change rate (%).

 As shown in FIG. 6, in the case of the cable according to the comparative example, it can be seen that the resistance change rate exceeds 25% which is a reference value when the number of twists reaches approximately 20,000 to 25,000.

On the other hand, in the case of the cable according to the embodiment of the present invention it can be seen that even if the number of twists exceeds 500,000 times, the resistance change rate is not less than 5.0%, which is significantly smaller than the reference value of 25%.

Although described with reference to a preferred embodiment of the present invention, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims described below. There will be. Therefore, it should be seen that all modifications included in the technical scope of the present invention are basically included in the scope of the claims of the present invention.

Claims (14)

Central intervention; At least one inner core surrounding the central interposition; At least one first interposition surrounding the central interposition and disposed between the inner cores; An inner binding tape surrounding and enclosing the inner core and the first interposition and made of an unsintered fluorine resin; At least one outer core surrounding an outer side of the inner binding tape; At least one second interposition provided on an outer side of the inner binding tape; An outer binding tape which binds the outer core and the second interposition and is made of an unsintered fluororesin; A shielding layer provided on an outer side of the outer binding tape; And, Cable for a robot comprising a; sheath provided on the outside of the shielding layer. The method of claim 1, The inner core includes a first conductor having a plurality of first wires twisted at a predetermined first pitch, and a first insulating layer provided on an outer side of the first conductor, The first pitch is a robot cable, characterized in that 15 to 30 times the outer diameter of the first conductor. The method of claim 1, The outer core may include a second conductor in which a plurality of second wires are twisted at a predetermined second pitch, a core part in which the plurality of second conductors are twisted in a predetermined third pitch, and an outer side of the core part. 2 insulation layers, The second pitch corresponds to 15 times to 50 times the outer diameter of the second conductor, and the third pitch corresponds to the robot 10 to 30 times the outer diameter of the core portion. The method according to claim 2 or 3, The first wire rod and the second wire rod of the inner core and the outer core has a yield strength increase rate of 1% to 30% of the robot cable. The method of claim 1, The unsintered fluorine resin robot cable, characterized in that made of unsintered PTFE (Unsintered Polytetrafluoroethylene) resin. The method of claim 1, And the inner binding tape and the outer binding tape have a coefficient of friction between 0.05 and 0.2. The method of claim 1, The first and second intervening cables for the robot, characterized in that each having an outer diameter corresponding to the outer diameter of the inner core and the outer core. The method of claim 7, wherein The outer diameter of the first interposition and the second interposition is a robot cable, characterized in that the outer diameter of 80% to 120% compared to the outer diameter of the inner core and the outer core. The method of claim 1, At least one of the center interposition, the first interposition and the second interposition is a cable for a robot, characterized in that formed by twisting the elastic yarn (elastic yarn). The method of claim 9, The elastic yarn is a robot cable, characterized in that made of polyester yarn (polyester yarn). The method of claim 1, And a further binding tape between the shielding layer and the sheath. The method of claim 11, The additional binding tape is a robot cable, characterized in that made of unsintered PTFE (Unsintered Polytetrafluoroethylene) resin. The method of claim 1, The sheath is a robot cable, characterized in that formed by tube type extrusion. A plurality of inner cores disposed on an outer circumferential surface of the center interposition of the circular cross section; An inner binding tape for binding the outer core; A plurality of outer cores disposed on an outer circumferential surface of the inner binding tape; An outer binding tape for binding the outer core; A shielding layer provided on an outer side of the outer binding tape; And, It includes; sheath provided on the outside of the shielding layer, And the inner binding tape and the outer binding tape are composed of an unsintered fluorine resin having a coefficient of friction between 0.05 and 0.2.

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