Robot cable having excellent torsional durability

Abstract

The present invention relates to a robot cable having excellent torsional durability. Even if the present invention is used in an environment where torsion and the like is frequently applied, torsional durability and service life can be significantly increased, and torsional durability is improved to minimize process interruption in an industrial site, thereby enabling loss caused by process interruption to be minimized. The present invention provides the robot cable comprising: a center insert disposed at the center; at least one inner core surrounding the center insert; an inner binding tape which surrounds and binds the inner core and which is formed of a fluorine resin; at least one outer core surrounding the outside of the inner binding tape; an outer binding tape which surrounds and binds the outer core and which is formed of a fluorine resin; and a sheath layer provided on the outside of the outer binding tape, wherein the inner core and the outer core are coated with a lubricating material.

Description

Robotic cables with excellent torsional durability

[0001] The present invention relates to a robot cable having excellent torsional durability. Specifically, the present invention aims to provide a robot cable that can significantly enhance torsional durability and service life even when used in environments subject to frequent torsion and other stresses.

[0002] Typically, industrial robots perform various tasks, such as welding, painting, and transporting, on machine parts production lines. These industrial robots are connected to a central controller via a robot cable, which not only supplies them with power but also receives various information necessary for their work.

[0003] However, industrial robots undergo continuous movement during their various tasks. Therefore, the cables used in industrial robots are subjected to fatigue loads such as repeated tension, torsion, and bending.

[0004] Accumulated fatigue loads on robot cables can cause cable breaks, which can lead to an abnormal production line shutdown. This requires significant time and effort to replace the robot cables, and the resulting production line shutdown can incur significant damage proportional to the time required to replace the robot cables.

[0005] Robotic cables require extreme durability, and torsional resistance, in particular, is significantly influenced by the cable's structure and materials. Experience has shown that torsional resistance is best achieved by preventing external torsional loads from being transferred internally. Therefore, a structure that reduces friction is crucial.

[0006] To ensure durability and flexibility in robot cables, conventional technology often involves segmenting conductors, and in the case of power cables, many cables are arranged in two or more layers. While these cables are constructed by linking each layer in the same direction (e.g., S / S or Z / Z) to ensure flexibility and windability, they suffer from low torsional durability and service life.

[0007] Therefore, there is a need to develop a robot cable that can minimize damage caused by breakage of the robot cable by ensuring high durability even in a long-term torsional stress driving environment.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] Patent Document 1: Korean Patent Publication No. 10-2018-0131219 (published on December 10, 2018)

[0011] The present invention aims to provide a robot cable having excellent torsional durability and significantly increased durability even when the robot cable is frequently used in an environment where torsion or the like is applied.

[0012] The problems solved by the present invention are not limited to those mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0013] As a means to solve the aforementioned technical challenges,

[0014] The present invention provides a robot cable comprising: a central member disposed in the center; at least one inner core surrounding the central member; an inner binding tape surrounding and binding the inner core and made of a fluororesin; at least one outer core surrounding the outer side of the inner binding tape; an outer binding tape surrounding and binding the outer core and made of a fluororesin; and a sheath layer provided on the outer side of the outer binding tape; wherein the inner core and the outer core are characterized in that a lubricating material is applied thereto.

[0015] In addition, the present invention provides a robot cable characterized in that the direction of the inner core and the direction of the outer core are opposite to each other.

[0016] In addition, the present invention provides a robot cable characterized in that the inner core includes a first assembly conductor and a first insulating layer, and two or more of the inner cores are combined to form a layer surrounding the central interposition.

[0017] In addition, the present invention provides a robot cable characterized in that the outer core includes a second assembly conductor and a second insulation layer, and two or more of the outer cores are combined to form a layer surrounding the outer side of the inner binding tape.

[0018] In addition, the present invention provides a robot cable characterized in that the stripping force, which is the minimum force for stripping the sheath layer from the outer core of the robot cable, is 10 N to 50 N.

[0019] In addition, the present invention provides a robot cable characterized in that the lubricating material is any one of polyolefin oil, Teflon oil, paraffin oil, mineral oil, polyol ester oil, polyester oil, and silicone oil.

[0020] In addition, the present invention provides a robot cable characterized in that the fluororesin is formed of a Teflon (polytetrafluoroethylene, PTFE) material.

[0021] In addition, the present invention provides a robot cable characterized in that the coefficient of friction between the inner core and the inner binding tape and between the outer core and the outer binding tape is 0.05μ to 0.15μ.

[0022] In addition, the present invention provides a robot cable characterized in that the axial deformation amplitude and maximum torque decrease as the combined pitch of the outer core increases.

[0023] In addition, the present invention provides a robot cable characterized in that the union pitch of the outer core is 80 mm or more.

[0024] In addition, the present invention provides a robot cable characterized in that the central member is formed of any one of cotton yarn, aramid yarn, and polyester yarn.

[0025] In addition, the present invention provides a robot cable characterized in that the sheath is formed by hose-type or tube-type extrusion.

[0026] In addition, the present invention provides a robot cable characterized in that the sheath is made of one of PVC (Polyvinyl chloride) and TPU (Thermoplastic Polyurethanes).

[0027] According to the robot cable according to the present invention, the torsion durability and durability can be significantly increased even when used in an environment where torsion or the like frequently occurs.

[0028] In addition, according to the robot cable according to the present invention, since the torsional durability is improved, process interruptions in industrial sites can be minimized, and thus losses due to process interruptions can be minimized.

[0029] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

[0030] The attached drawings are intended to explain the contents of the present invention in more detail to a person skilled in the art, but the technical idea of ​​the present invention is not limited thereto.

[0031] Fig. 1 is a cross-sectional view showing the internal configuration of a robot cable according to one embodiment of the present invention.

[0032] FIG. 2 is a graph showing the change rate of axial deformation amplitude (%) of each inner core pitch as the outer core pitch increases according to the present invention.

[0033] FIG. 3 is a graph showing the maximum torque (Nm) of each inner core pitch as the outer core pitch increases according to the present invention.

[0034] Figure 4 is a graph showing the change rate of axial strain amplitude (%) according to the directional arrangement of the inner core and outer core according to the present invention.

[0035] Figure 5 is a graph showing the maximum torque (Nm) according to the directional arrangement of the inner core and outer core according to the present invention.

[0036] Figure 6 is a photograph showing an experiment measuring the coefficient of friction (μ) between the inner core and the outer core according to the directional arrangement of the inner core and the outer core according to the present invention.

[0037] Figure 7 is a graph showing the coefficient of friction (μ) for each pitch of the inner core according to the directional arrangement of the inner core and outer core according to the present invention.

[0038] FIG. 8 is a graph showing the coefficient of friction (μ) between the inner core and outer core and the binding tape according to the directional arrangement of the inner core and outer core according to the present invention, depending on the presence or absence of binding tape and the presence or absence of application of a lubricating material.

[0039] Fig. 9 is a photograph showing a torsional durability tester for a robot cable according to the present invention.

[0040] Figure 10 is a graph comparing the change in pull-out load (N) according to the direction of connection between the inner core and the outer core and the presence or absence of application of a lubricating material according to the present invention.

[0041] Fig. 11 is a photograph showing a torsional durability tester for a robot cable according to the present invention.

[0042] The above-described purposes, other purposes, features, and advantages of the present invention will be readily understood through the following preferred embodiments, illustrated in the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosure is thorough and complete, and to ensure that the spirit of the present invention is fully conveyed to those skilled in the art.

[0043] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the purpose of effectively explaining the technical contents.

[0044] When terms such as "first," "second," etc. are used herein to describe components, these components are not intended to be limited by these terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also encompass complementary embodiments.

[0045] Additionally, the terminology used herein is for the purpose of describing specific examples and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise. As used herein, the terms "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0046]

[0047] Fig. 1 is a cross-sectional view showing the internal configuration of a robot cable (100) according to one embodiment of the present invention.

[0048] As illustrated in FIG. 2, a robot cable (100) according to the present invention includes a central member (10) disposed at a center, at least one inner core (20) surrounding the central member (10), an inner binding tape (40) surrounding and binding the inner core (20) and made of a fluororesin, at least one outer core (30) surrounding the outer side of the inner binding tape, an outer binding tape (50) surrounding and binding the outer core (30) and made of a fluororesin, and a sheath layer (70) provided on the outer side of the outer binding tape (50).

[0049] In the above robot cable (100), the inner core (20) may be configured for communication to exchange information with the outside, and the outer core (30) may be configured for power supply.

[0050] The above-mentioned central interposition (10) can be formed of any one of cotton yarn, aramid yarn, and polyester yarn, and preferably can be formed of aramid yarn.

[0051] The inner core (20) includes a first assembly conductor (21) and a first insulating layer (22), and two or more inner cores (20) may be combined to form a layer surrounding the central interposition (10), and the outer core (30) includes a second assembly conductor (31) and a second insulating layer (32), and two or more outer cores (30) may be combined to form a layer surrounding the outer side of the inner binding tape (40). The insulating layer (22, 32) covering the assembly conductors (21, 31) may be formed of polyethylene (PE) or high density polyethylene (HDPE).

[0052] The sheath (70) layer stripping force of the robot cable (100) according to the present invention can be measured using a UTM (Universal Testing Machine) facility, and for example, after stripping the sheath (70) layer to a length of 5 cm from one end of a cable specimen having a length of 13 cm, the core from which the sheath (70) layer has been stripped is placed inside a holder having an upper hole having a diameter larger than the core diameter and smaller than the outer diameter of the cable, while penetrating the upper hole, and the core penetrating the upper hole is fixed to the upper grip of the UTM facility, and the lower part of the holder is fixed to the lower grip of the UTM facility, and then the lower grip of the UTM facility is pulled downward at a speed of 150 mm / min, and the force at the moment when the sheath (70) layer is stripped from the core, i.e., the stripping force, can be measured.

[0053] The stripping force, which is the minimum force required to strip the sheath (70) layer from the robot cable (100), may be about 10N to 50N. The stripping force may preferably be 10N or more, 15N or more, 20N or more, 25N or more, 30N or more, 35N or more, 40N or more, or 45N or more, and preferably 50N or less, 45N or less, 40N or less, 35N or less, 30N or less, 25N or less, 20N or less, or 15N or less.

[0054] If the above-mentioned stripping force is less than 10 N, the components arranged under the sheath (70) of the robot cable (100) may easily come off, which may result in structural stability failure, deterioration of the emotional quality, and deterioration of the appearance quality. In addition, if the stripping force is too low, there is a problem that heat shrinkage may occur or the shrinkage rate due to the solvent may increase, so it is important to maintain the minimum stripping force to prevent this and secure durability.

[0055] On the other hand, when the stripping force exceeds 50 N, the adhesive force formed between the outer core (30) and the sheath (70) layer is excessive, so that the stripping work of the cable end sheath (70) layer for cable installation is not easy, and problems such as insulating material remaining on the surface of the outer core (30) after stripping may occur. In addition, when deformation occurs due to torsion, the torsional load or deformation on the outside may be transmitted to the inside through the compressed sheath (70) layer due to the high stripping force of the sheath layer (70), which may deteriorate the torsional durability.

[0056] The inner binding tape (40) and outer binding tape (50) surround and bind the inner core (20) and outer core (30) and may be made of a fluororesin having a relatively low coefficient of friction and strong lubricity. For example, the fluororesin may be formed of a Teflon (polytetrafluoroethylene, PTFE) material.

[0057] In addition, the inner core (20) and the outer core (30) can be coated with a lubricating material (60) which is a low-friction oil to significantly improve the torsional durability of the robot cable (100) of the invention. The lubricating material (60) which is a low-friction oil may be any one of polyolefin oil, Teflon oil, paraffin oil, mineral oil, polyol ester oil, polyester oil, and silicone oil. Preferably, silicone oil may be used, but various embodiments are possible as long as the oil has a friction coefficient equivalent to that of silicone oil.

[0058] Here, the lubricating material (60) can be applied in the insulation process of forming the first insulation layer (22) of the inner core (20) and the second insulation layer (32) of the outer core (30). In each insulation process, the lubricating material (60) can be applied using a tool such as a dropper before being wound on a bobbin after passing through a die.

[0059] In addition, the above-mentioned system (70) can be formed by hose-type or tube-type extrusion. The hose-type extrusion method refers to the tube-type extrusion method, and since it can lower the adhesive strength compared to the existing solid type, it can improve the torsional durability of the robot cable (100).

[0060] The above-mentioned sis (70) can be formed from a composition containing a polyethylene resin, a polyolefin resin or a polyurethane resin as a base resin, and can preferably be made of PVC (Polyvinyl chloride) and TPU (Thermoplastic Polyurethanes).

[0061]

[0062] FIG. 2 is a graph showing the change rate of axial deformation amplitude (%) of each inner core (20) pitch as the outer core (30) pitch increases according to the present invention, FIG. 3 is a graph showing the maximum torque (Nm) of each inner core (20) pitch as the outer core (30) pitch increases according to the present invention, FIG. 4 is a graph showing the change rate of axial deformation amplitude (%) according to the axial arrangement of the inner core (20) and the outer core (30) according to the present invention, and FIG. 5 is a graph showing the maximum torque (Nm) according to the axial arrangement of the inner core (20) and the outer core (30) according to the present invention.

[0063] As shown in FIGS. 2 and 3, it can be seen that as the union pitch of the outer core (30) increases to 80 mm or more, the axial strain amplitude and maximum torque, which are the magnitudes of the deformation that occur when the cable is bent or stretched, decrease.

[0064] Here, the rate of change for the "axial strain amplitude" is called the "axial strain amplitude change rate." Specifically, when a twist condition of + and - twist angles is applied to the internal components of the cable, the internal components of the cable are subjected to tension and compression for the corresponding twist angles. In this case, the difference between the tensile strain and the compressive strain received by the internal core is called the "axial strain amplitude change rate." This is related to the fatigue characteristics of the cable, and the lower the axial strain amplitude change rate, the longer the life of the cable.

[0065] Torque is also the circumferential resistance to torsion, and can be expressed as T (torque) = F (force acting on each component inside the cable) x r (radius). As with the rate of change of axial strain amplitude, torque also improves the life of the cable because the radius of rotation of the core can be reduced as friction is lowered.

[0066] Referring to FIGS. 2 and 3, it can be confirmed that as the union pitch of the outer core (30) increases, the axial deformation amplitude and maximum torque decrease, assuming that the union pitch of the inner core (20) is the same. It was confirmed that the union pitch of the inner core (20) does not have a large difference in the axial deformation amplitude and maximum torque when the union pitch is 60 mm, 80 mm, or 100 mm, and thus the union pitch of the inner core (20) does not have a large effect on the axial deformation amplitude and maximum torque.

[0067]

[0068] In addition, as shown in FIGS. 4 and 5, when the twisting directions of the inner core (20) and the outer core (30), i.e., the rolling directions, are arranged in opposite directions, for example, in the S / Z or Z / S direction, the axial deformation amplitude and the maximum torque are reduced.

[0069] In the case where the direction of the inner core (20) and the outer core (30) are the same as in the past, even if the pitches of the inner core (20) and the outer core (30) are different, a point may occur where the pitches of the inner core (20) and the outer core (30) become the same due to the slippage of the inner core (20) or the outer core (30) during torsion. Accordingly, since the outer core (30) can penetrate between the grooves of the inner core (20), the core no longer slips and is fixed, so that the torsional deformation on the outside is transmitted as is to the inner core (20), and as a result, the stress of the cable increases and the lifespan may be reduced. In order to improve such a problem of the past, the direction of the inner core (20) and the outer core (30) are made different so that sliding between the cores can occur continuously, thereby increasing the torsional lifespan.

[0070] For example, when the rolling directions of the inner core (20) and the outer core (30) are arranged in the same direction, for example, in the S / S or Z / Z direction, the axial strain amplitude is 1.94%, whereas when the rolling directions are arranged in different directions, such as the S / Z or Z / S direction, the axial strain amplitude is reduced to 1.68%. In addition, when the rolling directions of the inner core (20) and the outer core (30) are arranged in the S / S or Z / Z direction, the maximum torque is 4.62 Nm, whereas when the rolling directions are arranged in different directions, such as the S / Z or Z / S direction, the maximum torque is reduced to 4.42 Nm.

[0071]

[0072] FIG. 6 is a photograph showing an experiment measuring the coefficient of friction (μ) between the inner core (20) and the outer core (30) according to the longitudinal arrangement of the inner core (20) and the outer core (30) according to the present invention, FIG. 7 is a graph showing the coefficient of friction (μ) by pitch of the inner core according to the longitudinal arrangement of the inner core (20) and the outer core (30) according to the present invention, and FIG. 8 is a graph showing the coefficient of friction (μ) between the inner core (20) and the outer core (30) and the binding tape (40, 50) according to the longitudinal arrangement of the inner core (20) and the outer core (30) according to the present invention, depending on the presence or absence of the binding tape (40, 50) and the presence or absence of the application of a lubricating material (60).

[0073] Referring to Fig. 6, equipment for precisely measuring the coefficient of friction between materials constituting a robot cable (100) was manufactured, and the coefficient of friction between the sheath (70) and the tape, the insulating layer (22, 32) and the tape, and the inner core (20) and the outer core (30) was measured.

[0074]

[0075] Referring to Fig. 7, when the pitch of the inner core is 18 mm, 26 mm, and 36 mm, the coefficient of friction is lower when the direction of the inner core (20) and the outer core (30) is arranged in the S / Z or Z / S direction than when the direction of the inner core (20) and the outer core (30) is arranged in the Z / Z or S / S direction. Therefore, when the direction of the inner core (20) and the outer core (30) is arranged in the S / Z or Z / S direction, low friction between the inner core (20) and the outer core (30) can be implemented, and the durability can be improved.

[0076]

[0077] Referring to Fig. 8, the coefficient of friction was confirmed according to the presence or absence of internal and external binding tapes (40, 50) made of fluororesin that surround and bind the internal core (20) and external core (30) according to the arrangement of the inner core (20) and the outer core (30) in the direction of rotation, and the presence or absence of a lubricating material (60) applied to the internal core (20) and the outer core (30).

[0078] As a result, even when the direction of the inner core (20) and the outer core (30) is arranged in the Z / Z or S / S direction, the coefficient of friction is lowered by wrapping the inner core (20) and the outer core (30) with Teflon (PTFE) tape and binding them, and it was confirmed that the coefficient of friction is further lowered when wrapping the inner core (20) and the outer core (30) with Teflon (PTFE) tape and binding them, and additionally applying a lubricating material (60) to the inner core (20) and the outer core (30).

[0079] In addition, when the rolling direction of the inner core (20) and the outer core (30) is arranged in the S / Z or Z / S direction, it was confirmed that the coefficient of friction is much lower than when the rolling direction of the inner core (20) and the outer core (30) is arranged in the Z / Z or S / S direction, and thus the effect is confirmed to be increased.

[0080] Accordingly, the coefficient of friction between the inner core (20) and the inner binding tape (40) may be 0.05μ to 0.15μ, 0.06μ to 0.14μ, 0.07μ to 0.13μ, 0.08μ to 0.12μ, or 0.09μ to 0.11μ, and the coefficient of friction between the outer core (30) and the outer binding tape (50) may be 0.05μ to 0.15μ, 0.06μ to 0.14μ, 0.07μ to 0.13μ, 0.08μ to 0.12μ, or 0.09μ to 0.11μ.

[0081]

[0082] Fig. 9 is a photograph showing a torsional durability tester for a robot cable (100) according to the present invention, and Fig. 10 is a graph comparing changes in pull-out load (N) according to the direction of connection between the inner core (20) and the outer core (30) and the presence or absence of application of a lubricating material (60) according to the present invention.

[0083] The graph shows the change in pull-out load (N) according to the case where the inner core (20) and outer core (30) are arranged in the same direction as the S / S or Z / Z direction and no lubricating material (60) is applied to the inner core (20) and outer core (30), and the case where the inner core (20) and outer core (30) are arranged in opposite directions as the Z / S or S / Z direction and a lubricating material (60) is applied to the inner core (20) and outer core (30).

[0084] In addition, the pull-out load is defined as the force (N) required by friction with the outer core (30) when pulling out the inner core (20). That is, the larger the pull-out load, the greater the frictional force between the inner core (20) and the outer core (30), and conversely, the smaller the pull-out force, the smaller the frictional force between the inner core (20) and the outer core (30).

[0085] Specifically, the pull-out load is measured by fixing the gland to the pull-out test jig by applying a cable fixing structure (e.g., a gland for a harness), inserting the cable into the gland, tightening the cable with a specified torque, fixing the core, and pulling it with a tensile tester. When the core is pulled out, the load at this time is measured, and the low friction of the binding tape or the lower part of the sheath layer can be evaluated. Since a lower load when the core is pulled out means lower friction, it can be used as a measure to estimate the durability of the core under actual cable conditions.

[0086]

[0087] Referring to Fig. 10, it can be seen that the pull-out load is small when the inner core (20) and the outer core (30) are arranged in opposite directions in the Z / S or S / Z direction and a lubricating material (60) is applied to the inner core (20) and the outer core (30). Therefore, in the case of the robot cable (100) according to the present invention, even if torsion or the like frequently occurs due to frequent movement, the pull-out load is small, and the frictional force between the inner core (20) and the outer core (30) is small due to the internal binding tape (40), which is advantageous for torsion durability.

[0088]

[0089] Fig. 11 is a photograph showing a torsional durability tester for a robot cable (100) according to the present invention.

[0090] As shown in the photo in Fig. 11, the results of testing the torsional durability of the robot cable (100) according to the present invention were as shown in Table 1 below.

[0091] Classification Sample 1 Sample 2 Sample 3 Conductor Same Same Same Same Insulation Same Same Same Union (Direction) S / SS / SZ / S Binder Tape PTFE PTFE PTFE Lubricant applied None None Sheath method Hose type Hose type Hose type Torsion durability (times) 8,000 74,000 500,000 or more

[0092]

[0093] In the case of sample 1, when the rolling directions of the inner core (20) and the outer core (30) are in the same direction, S / S or Z / Z, and no lubricating material (60) is applied to the inner core (20) and the outer core (30), the torsional durability was only 8,000 times, and in the case of sample 2, when the rolling directions of the inner core (20) and the outer core (30) are arranged in the opposite direction, Z / S or S / Z, and no lubricating material (60) is applied to the inner core (20) and the outer core (30), the torsional durability was only 74,000 times. On the other hand, in the case of sample 3, like the robot cable (100) of the present invention, the rolling directions of the inner core (20) and the outer core (30) are arranged in the opposite direction, Z / S or S / Z, and a lubricating material (60) is applied to the inner core (20) and the outer core (30). When material (60) was applied, the torsional durability was confirmed to be significantly longer than that of sample 2, exceeding 500,000 times.

[0094]

[0095] Therefore, according to the robot cable according to the present invention, the torsion durability and durability life can be significantly increased even when used in an environment where torsion, etc. frequently occurs.

[0096] In addition, according to the robot cable according to the present invention, since the torsional durability is improved, process interruptions in industrial sites can be minimized, and thus losses due to process interruptions can be minimized.

[0097]

[0098] Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering its technical spirit or essential characteristics. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

[0099] [Explanation of symbols]

[0100] 100: Robotic Cable 40: Internal Binding Tape

[0101] 10: Center insert 50: Outer binding tape

[0102] 20: Inner core 60: Lubricating material

[0103] 21: First collective conductor 70: Sheath layer

[0104] 22: First insulation layer

[0105] 30: Outer core

[0106] 31: Second collective conductor

[0107] 32: Second insulation layer

Claims

1. Central intervention placed in the center; At least one inner core surrounding the central member; An inner binding tape made of fluororesin that surrounds and binds the inner core; At least one outer core surrounding the outer side of the inner binding tape; An outer binding tape made of fluororesin that surrounds and binds the outer core; and A sis layer provided on the outer side of the above external binding tape; A robot cable, characterized in that the inner core and outer core are coated with a lubricating material.

2. In paragraph 1, A cable for a robot, characterized in that the direction of the inner core and the direction of the outer core are opposite to each other.

3. In paragraph 1, A robot cable, characterized in that the inner core includes a first assembly conductor and a first insulation layer, and two or more of the inner cores are combined to form a layer surrounding the central interposition.

4. In paragraph 1, A robot cable, characterized in that the outer core includes a second assembly conductor and a second insulation layer, and two or more of the outer cores are combined to form a layer surrounding the outer side of the inner binding tape.

5. In paragraph 1, A robot cable, characterized in that the minimum force for removing the sheath layer from the robot cable is 10N to 50N.

6. In paragraph 1, A robot cable, characterized in that the lubricating material is any one of polyolefin oil, Teflon oil, paraffin oil, mineral oil, polyol ester oil, polyester oil, and silicone oil.

7. In paragraph 1, A robot cable, characterized in that the above fluororesin is formed of Teflon (Polytetrafluoroethylene, PTFE) material.

8. In paragraph 1, A robot cable, characterized in that the coefficient of friction between the inner core and the inner binding tape and between the outer core and the outer binding tape is 0.05μ to 0.15μ.

9. In paragraph 1, The above robot cable is characterized in that the axial strain amplitude and maximum torque decrease as the union pitch of the outer core increases.

10. In paragraph 1, A robot cable, characterized in that the union pitch of the outer core is 80 mm or more.

11. In paragraph 1, A robot cable, characterized in that the above-mentioned central member is formed of any one of cotton yarn, aramid yarn, and polyester yarn.

12. In paragraph 1, A robot cable, characterized in that the above-mentioned sheath is formed by hose-type or tube-type extrusion.

13. In paragraph 1, A robot cable, characterized in that the above sheath is made of either PVC (Polyvinyl chloride) or TPU (Thermoplastic Polyurethanes).

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