JP2008218061A - Flex-resistant and twist-resistant cable and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of using a fluororesin and an ultraviolet curing resin composition as an insulator to improve mutual lubricity of insulators of an insulated core wire that complex processes such as resin coating and curing are required in addition to high price. <P>SOLUTION: For a typical example, a multi-core cable is structured by intertwining the insulated core wires for which a thermoplastic resin is coated as an insulator around an outer circumference of a conductor. The thermoplastic resin is composed of polyester elastomer and the flex-resistant and twist-resistant cable contains 0.5 to 3.0 wt.% organic high-molecular weight silicone polymer. Thus, it is possible to provide a cable for a factory automation device such as an industrial robot and the like that is capable of being manufactured by extrusion molding using an normal inexpensive thermoplastic resin, inexpensive, excellent in flex-resistance, twist-resistance and flexibility and having better lubricity of an insulator surface than an expensive fluororesin. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a cable used in an FA device such as an industrial robot that is inexpensive and is excellent in bending resistance, torsion resistance, and flexibility by improving the slipping property between insulators of an insulating core wire. Is.

As shown in FIG. 4, the conventional robot cable 1 ″ has a configuration in which conductors 2 ″ are covered with an insulator 3 ″, which are assembled and further covered with an external sheath 6 ″.
Cables used for industrial robots and the like are required to be strong in bending and twisting. Therefore, when “high durability” is required for conductors, for example, Sn-containing copper alloys are used instead of pure copper. The copper alloy is used. However, although the copper alloy increases the mechanical strength, the conductivity decreases. Therefore, the conductor must be made thicker in order to suppress the generation of Joule heat, which goes against the reduction in the diameter and weight of the cable. In addition, the price of copper alloys is higher than that of copper, leading to an increase in cable prices.
Insulators coated on the outer circumference of the conductor, polyvinyl chloride or polypropylene is used for the “low durability cable”, and ethylene tetrafluoroethylene (ETFE), tetrafluoroethylene hexafluoropropylene is used for the “high durability cable”. Fluororesin such as (FEP) is used. Fluororesin has low sliding friction resistance and has a certain degree of hardness, which improves the slipperiness between insulators, prevents conductor breakage and damage, and provides bending resistance and twist resistance. It has been used to make it possible to increase sex. However, since fluororesin is expensive compared to other insulating materials, there is a problem that it leads to an increase in cable price.
In order to improve the slipperiness between insulators, JP-A-2000-357418 shown below provides a urethane acrylate UV curable resin composition containing silicone on a polyvinyl chloride insulating layer. An insulated wire is disclosed. However, since it is an ultraviolet curable resin composition, there is a problem that a complicated process of applying and curing a resin is required.

JP 2000-357418 A

  Therefore, the object of the present invention is made in view of the above points, and it is possible to use an insulating core without using an expensive copper alloy or an expensive fluororesin or ultraviolet curable resin composition as a conductor. Providing robot cables that have excellent lubricity on the surface of the wire insulator, can be extruded with ordinary low-cost thermoplastic resin, are inexpensive, strong in bending and twisting, and have excellent flexibility. There is.

The robot cable according to claim 1 is characterized in that the outer periphery of the conductor is covered with a polyester elastomer insulator containing 0.5 to 3.0 wt% of an organic high molecular weight silicone polymer. In this way, in a multi-core cable with a configuration in which a plurality of insulated core wires covered with an insulator material containing an organic high molecular weight silicone polymer are twisted and sheathed, silicone has a low affinity for other substances, and the surface Insulating cores that are twisted together when the cables are subjected to stresses such as bending and twisting, because the surface slippage between the insulated cores is good, and the cables are prevented from adhering to each other and impart releasability. It becomes easy for each other to move smoothly, and it contributes to the improvement of the bending / twisting life. Further, the flexibility of the cable itself can be improved by improving the sliding between the insulated core wires.
In addition, if an unnecessary restraining force acts between the assembly of the insulated core wires twisted together and the sheath in a multi-core cable, a large distortion occurs in the insulated core wires when the cable is bent or twisted, and bending, twisting, etc. However, by using the insulated core wire of the present invention, it is possible to reduce the frictional resistance between the assembly of the insulated core wires and the sheath, and to bend and twist the cable. When it receives, the influence on the insulation core wire is mitigated.
The reason why the content of the organic high molecular weight silicone polymer is set to 0.5 to 3.0% wt is less than 0.5 wt%, and sufficient surface lubricity cannot be imparted to the insulating core wire. Later, as described in Examples, 0.7 wt% or more showed particularly preferable results. On the other hand, if it exceeds 3 wt%, the insulator material slips between the screw and the cylinder at the time of extrusion molding, and the formability is deteriorated, resulting in poor appearance and reduced mechanical strength.
The robot cable according to claim 2 is characterized in that the insulator material is any one of polypropylene, polyvinyl chloride, and polyethylene. Conventionally, expensive fluororesin has been used to reduce the sliding frictional resistance of the insulation core, but by using the present invention, the sliding frictional resistance of the insulation core can be reduced with these low-cost insulator materials. Can be small.
According to a third aspect of the present invention, an organic high molecular weight silicone polymer made by graft polymerization of a reactive polyorganosiloxane to an insulator material is added to the insulator material. According to this method, even in a structure in which the insulator material and the silicone are chemically bonded, the same effect can be obtained by adding the same amount as the silicone equivalent amount.
In the fourth aspect, when an organic high molecular weight silicone polymer is added to an insulator material, an organic system is prepared using a master batch made by kneading the insulator material at a high concentration (30 to 50 wt%). A production method comprising adding a high molecular weight silicone polymer to an insulator material. Since the master batch is in the form of pellets, handling during measurement is easy, and the insulator material and organic high molecular weight silicone polymer are highly kneaded and dispersed in advance, so dispersion when blended into the insulator material Will be better.

  As described above, the present invention can provide a robot cable with greatly improved bending resistance, torsion resistance, and flexibility at low cost by improving the slipping property between insulators. , Its industrial value is great.

Hereinafter, the bending-resistant and twist-resistant cable and the manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings, taking typical examples.

  Here, the durability of a cable is the number of cycles of repeated bending until the conductor of the cable is disconnected. Usually, the left and right bending test and the twisting test are performed in the durability evaluation test of the robot cable. FIG. 3 (a) shows the left / right bending test, and FIG. 3 (b) shows the outline of the twist test and the test conditions. In addition, the configuration table of the bending / twisting-resistant cable 1 of the first to fourth embodiments of the present invention, the durability evaluation test result by the left / right bending test and the twisting test are shown in Table 1, and the cables of Comparative Examples 1-3 are shown. Table 2 shows the results of the durability evaluation test by the composition table, the left / right bending test and the twisting test.

The structure of the first embodiment of the present invention is shown in FIG. In the cable configuration of this embodiment, as is clear from FIG. 1 (a), the outer periphery of the conductor 2 is covered with an insulator, a plurality of the insulated core wires 4A are twisted, and the Japanese paper tape 5 and sheath are formed on the outer periphery. 6 was applied in order to obtain an outer diameter of 11.8 mm. Here, the insulator 3A is obtained by adding 0.7 wt% of an organic high molecular weight silicone polymer to a polyester elastomer. This cable was attached to the bending test shown in FIGS. 3 (a) and 3 (b), and the number of reciprocations at which disconnection occurred was determined. Table 1 shows the results of the durability evaluation test.
The structure of the second embodiment of the present invention is shown in FIG. The insulator 3B of this example is obtained by adding 1.5 wt% of an organic high molecular weight silicone polymer to a polyester elastomer, and the other configuration is the same as that of the first example. This cable was attached to the bending test shown in FIGS. 3 (a) and 3 (b), and the number of reciprocations at which disconnection occurred was determined. Table 1 shows the results of the durability evaluation test.
The structure of the third embodiment of the present invention is shown in FIG. The insulator 3C of this example is obtained by adding 0.7 wt% of a graft type organic high molecular weight silicone polymer in terms of silicone to a polyester elastomer, and the other configuration is the same as that of the first example. This cable was attached to the bending test shown in FIGS. 3 (a) and 3 (b), and the number of reciprocations at which disconnection occurred was determined. Table 1 shows the results of the durability evaluation test. As is clear when comparing the first and third examples, the same amount of graft type organic high molecular weight silicone can be added in terms of silicone. For example, it can be seen that the same effect as the organic high molecular weight silicone of Example 1 is obtained.
The structure of the fourth embodiment of the present invention is shown in FIG. The insulator 3D of this example is obtained by adding 0.7 wt% of an organic high molecular weight silicone polymer to polypropylene, and the other configuration is the same as that of the first example. This cable was attached to the bending test shown in FIGS. 3 (a) and 3 (b), and the number of reciprocations at which disconnection occurred was determined. Table 1 shows the results of the durability evaluation test.

Next, in order to compare the effect of the present invention with the prior art, cables of Comparative Examples 1 to 3 according to the prior art were prepared.
The structure of Comparative Example 1 is shown in FIG. The effect of the addition amount of the organic high molecular weight silicone polymer was compared in the bending characteristics between the first and second examples and the comparative example 1. In Comparative Example 1, the amount of the organic high molecular weight silicone polymer added was 0, and the others were prepared in the same manner as in Example 1 (and Example 2), and the bending test was performed under exactly the same conditions. The evaluation test results are shown in Table 2. The cable of Comparative Example 1 with an addition amount of 0 was disconnected at 450,000 times in the left / right bending test, and was disconnected at 20,000 times in the twisting test. Disconnection at 10,000 times and no disconnection at 2 million times in the twist test. The cable of Example 2 with an addition amount of 1.5 wt% does not break at 850,000 times in the left / right bending test, and does not break at 2 million times in the twist test. From these results, it can be seen that the bending resistance of the present invention is improved as compared with the conventional product.
The structure of Comparative Example 2 is shown in FIG. The effect of the addition amount of the organic high molecular weight silicone polymer was compared between the fourth example and the comparative example 2 in the case where the insulator was polypropylene and the bending characteristics were compared. In Comparative Example 2, the amount of the organic high molecular weight silicone polymer added was 0, and the others were prepared in the same manner as in Example 4, and the bending test was performed under exactly the same conditions. The evaluation test results are shown in Table 2. The cable of Comparative Example 2 with an addition amount of 0 was disconnected at 100,000 times in the left / right bending test and disconnected at 50,000 times in the twisting test, but the cable of Example 4 with an addition amount of 0.7% was bent left / right. Disconnection after 400,000 times in the test, and no disconnection even after 2 million times in the twist test. From these results, it can be seen that, similarly to Comparative Example 1, the present invention has improved bending resistance compared to the conventional product.
The structure of Comparative Example 3 is shown in FIG. The bending characteristics of the effects of the addition amount of the organic high molecular weight silicone polymer were compared between the first and second examples and the comparative example 3. ETFE, which is a fluororesin, was used as the insulator material, and the others were prepared in the same manner as in Example 1 (and Example 2), and the bending test was performed under exactly the same conditions. The evaluation test results are shown in Table 2. The cable of Comparative Example 3 is disconnected at 460,000 times in the left / right bending test, and is disconnected at 2 million times in the twisting test. The cable of Example 1 in which 0.7 wt% of organic high molecular weight silicone polymer was added to the polyester elastomer was disconnected at 650,000 times in the left / right bending test, and was not disconnected even at 2 million times in the twisting test. The cable of Example 2 with an addition amount of 1.5 wt% does not break at 850,000 times in the left / right bending test, and does not break at 2 million times in the twist test. From these results, the present invention is a prior art that improves the surface slipperiness between insulators, and when the cables are subjected to stress such as bending, the insulated core wires can move smoothly and have a flex life. It can be seen that the effect is superior to the fluororesin used for the purpose of “improving”.

  Although the present invention exemplifies a typical robot cable structure, the present invention is not limited to this structure, and the number of cores may be changed or a shield material may be used for the cable. It goes without saying that various modifications are included within the scope of the present invention.

  The bending and twisting resistant cable of the present invention can be used for robots and the like, but can be widely applied to machine tools and the like.

(A) is a cross-sectional view of the bending / twisting-resistant cable 1A of the first embodiment of the present invention, and (B) is a cross-sectional view of the bending / twisting-resistant cable 1B of the second embodiment of the present invention. (C) is a cross-sectional view of the bending / twisting resistant cable 1C of the third embodiment of the present invention, and (d) is a sectional view of the bending / twisting resistant cable 1D of the fourth embodiment of the present invention. It is sectional drawing. FIG. 6B is a cross-sectional view of the cable A ′ of Comparative Example 1, FIG. 5B is a cross-sectional view of the cable B ′ of Comparative Example 2, and FIG. (A) is a bending test method related to durability for the examples and comparative examples of the present invention, and (B) is a twist test method related to durability for the examples and comparative examples of the present invention. It is sectional drawing of the conventional cable 1 "for robots.

Explanation of symbols

1A Bending and twisting resistant cable of the first embodiment of the present invention 1B Bending and twisting resistant cable of the second embodiment of the present invention 1C Bending and twisting resistant cable of the third embodiment of the present invention 1D Bend-resistant and twist-resistant cable of 4th Example of invention 2 Conductor 3A Polyester elastomer insulator containing 0.7 wt% of organic high molecular weight silicone polymer 3B Polyester elastomer insulator containing 3 wt% of organic high molecular weight silicone polymer 3C Graft Type Organic high molecular weight silicone polymer 0.7wt% (silicone equivalent) containing polyester elastomer insulator 3D Organic high molecular weight silicone polymer 0.7wt% containing polypropylene insulator 4A Insulated core 4B Insulated core 4C Insulated core 4D Insulated Core 5 Washi tape 6 Sheath A 'Cable of Comparative Example 1 2' Conductor 3A ' Reester Elastomer Insulator B 'Cable of Comparative Example 2 3B' Polypropylene Insulator C 'Cable of Comparative Example 3 3C'ETFE (Ethylene Tetrafluoroethylene) Insulator 4A' Insulated Core 4B 'Insulated Core 4C' Insulated core 6 'Sheath 1 "Conventional robot cable 2" Conductor 3 "Insulator 5" Washi tape 6 "Sheath

Claims (4)

In a multi-core cable formed by twisting an insulation core wire coated with a thermoplastic resin as an insulator on the outer periphery of the conductor, the thermoplastic resin is made of a polyester elastomer, and an organic high molecular weight silicone polymer is 0.5 to A bending and twisting resistant cable characterized by containing 3.0 wt%. The cable according to claim 1, wherein the thermoplastic resin is any one of polypropylene, polyvinyl chloride, and polyethylene. The organic high molecular weight silicone polymer is produced by graft polymerization of reactive polyorganosiloxane to various insulator materials, and the amount added to the thermoplastic resin as an insulator is 0.5% to 3. The cable according to claim 1, wherein the cable is 0 wt%. Add organic high molecular weight silicone polymer to the insulator material using a masterbatch made by kneading the organic high molecular weight silicone polymer to the base insulator material at high concentration (30-50wt%) The method for manufacturing a cable according to any one of claims 1 to 3, wherein:

Images