JPS6367042B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cable conduit with significantly improved transmission efficiency. In the past, plastic coating was applied to the core wire of cable conduit, and plastic coating was applied to the inner surface of the outer cylindrical tube of cable conduit for the purpose of improving transmission efficiency, improving the feeling during operation, and further preventing rust. There are known methods in which a plastic tube is interposed between the core wire and the outer cylindrical tube. For example, French Patent No. 1078061 discloses the use of polyamide, polyurethane and polyethylene in the manner described above, as well as the use of these plastics directly as the outer tube. In Special Publication No. 37-4803, tubes (inner tubes) made of super polyamide etc. with a low coefficient of friction were used.
A mode is disclosed in which the core wire is fixedly inserted at at least one place between the core wire and the outer cylindrical tube (enclosure). In addition, Japanese Patent Publication No. 54-17864 discloses a case in which oil-impregnated plastic is attached to the core wire, and Japanese Patent Publication No. 48-42924 discloses a case in which a plastic tube is inserted inside an outer casing. , discloses an example of a combination embodiment in which the core wire is impregnated with a lubricant mainly composed of wax. The conventional technologies listed above have improved transmission efficiency,
The feeling is also good, especially the special public model Showa 54-17864.
The transmission efficiency in Special Publication No. 48-42924 is 80~
It has reached 90%. Although this efficiency value is extremely high, as the performance of machines, devices, etc. becomes higher, further improvement in efficiency is desired. The present inventors made an inner cable by coating a core wire with thermoplastic plastic having a low coefficient of friction,
We combined this inner cable with a flexible outer cylindrical tube that has thermoplastic plastic as the inner sliding surface, and as a result of conducting experiments with a plastic-plastic sliding contact mode, we found that the combination was specially designed. The present inventors have discovered that transmission efficiency and wear resistance can be significantly improved by selecting appropriate materials, leading to the present invention. That is, as the thermoplastic plastic to be applied to the core wire, a plastic with a low coefficient of friction and relatively high flexibility is used, and a thermoplastic plastic that forms the inner sliding surface of the flexible outer cylindrical tube is used. As a plastic, it has higher hardness and elastic modulus than the plastic coated on the core wire, and the coefficient of friction between the plastics in that combination is 0.20.
It was found that a combination smaller than Cable conduits are rarely used in straight lines, but are arranged in various curved manners to facilitate movement that involves changing the operating direction and to effectively transmit operating force. It is characterized by the fact that it makes it possible to do the following. Once the outer cylindrical tube is arranged in a certain manner, it maintains that manner, but the inner cable, which operates by sliding on the inside thereof, repeatedly slides and bends. Therefore, if the inner cable is coated with a relatively flexible plastic that has a low coefficient of friction, the inner cable will not become rigid, allowing smooth sliding during operation, and reducing the operating force. It was expected that the loss would be small, but on the other hand, there was concern that the applied plastic would be more flexible, so there would be more wear. As a result of various experiments, it was found that although the operating efficiency was as expected, the initial concerns regarding wear were not met. In other words, in combination with a flexible plastic on the inner sliding surface of the outer tube and a plastic with a relatively high elastic modulus on the inner cable,
On the other hand, the plastic of the inner cable suffered a great deal of wear, and the transmission efficiency also fell below the value of the above-mentioned combination. The core wire used in the present invention is a wire rope with a "7 wires 6 concentric" configuration, but it is not necessarily limited to this configuration, and wire ropes with other configurations or as the case may be. Single wires such as stainless steel wire and piano wire are also used. The core wire can be coated with thermoplastic by extrusion using a cross-head die, by welding by fluidized bed dipping, or by drying and baking after applying a plastic dispersion. Methods such as forming a film or fitting a heat-shrinkable tube are used. The thickness of thermoplastic plastic wire ropes shall be 0.2 to 0.5 mm out of 10 ^-1 mm, and the thickness of thermoplastic plastic wire shall be 0.05 ^to 0.2 mm out of ^{10 -1} mm. It is preferable. The thermoplastics used for adhesion are polyethylene, polytetrafluoroethylene (PTFE), polytetrafluoroethylene hexafluoropropylene (FEP), 11-
Examples include polyamides such as nylon, polypropylene, other polyether esters, and polyesters such as polybutylene terephthalate. In addition, the value of the coefficient of friction must be smaller than 0.20 (coefficient of kinetic friction) in all combinations with the thermoplastic plastic forming the inner sliding surface of the outer cylindrical tube described below. One embodiment of the flexible outer cylindrical tube of the present invention is a cylindrical tube in which steel wire or steel strips are tightly wound in a spiral manner. The outer circumferential surface of this cylindrical tube is usually provided with a protective coating such as polyvinyl chloride or polyethylene, and the inner circumferential surface is made of a thermoplastic selected in relation to the thermoplastic applied to the inner cable described above. are arranged to form a sliding surface. This plastic sliding surface may be coated on the inner circumferential surface of a spiral tube made of steel by coating a steel wire or steel strip coated with plastic in advance and tightly wound helically. Alternatively, the plastic tube may be formed separately and fitted into the cylindrical tube. As another embodiment of the flexible outer cylindrical tube, a relatively thick tube made of the thermoplastic selected as described above may be used as it is as the outer cylindrical tube. In yet another embodiment, a tube is formed using the thermoplastic selected as described above, and the tube is reinforced by winding a plurality of thin steel wires at a loose pitch around the outer circumferential surface of the tube. An integral tube coated with the same or a separate thermoplastic can be used as the outer tube. The above-mentioned selected thermoplastics are thermoplastics that have a relatively higher hardness and elastic modulus than the thermoplastics used for the inner cable, and in combination with each other, The coefficient of dynamic friction is less than 0.20. Table 1 illustrates thermoplastics with low coefficients of friction that may be used in the present invention.

[Table] The displayed bending elastic modulus and hardness are expressed as comparative model values, with PTFE as 1. A circle mark in the "Application location" column in the table indicates that it is used on the inner cable side or the outer tube side. Among these, polyethylene, polyamide, and polypropylene are used on both the inner cable side and the outer tube side. be done. However, if polyethylene is used for the inner cable side, it should be combined with the plastic used for the outer tube side that has a higher bending elastic modulus and hardness than this, and is shown in the bottom column of the table. do. In addition, if polyethylene is used on the outer cylinder tube side, the label will be displayed on the upper column side than the polyethylene.
A combination of PTFE and FEP will be used. As for polyethylene, it is preferable to use one having a relatively high molecular weight, since the molecular weight has a large effect on wear resistance. Polyamide is 6 nylon, 6-6 nylon,
Nylon 11 and nylon 12 are used as sliding materials, but the physical properties of these materials have a relatively large difference. The polyamide used for the inner cable side is preferably 6 nylon or 11 nylon, and the polyamide used for the outer tube side is preferably 6-6 nylon. Polyester is shown as not being used on the inner cable side in Table 1, but polybutyreterephthalate (PBT) in particular is relatively flexible, so it may be used on the inner cable side in some cases. can do. On the other hand, polyethylene terephthalate (PET) and polyarylate are used exclusively for the outer tube side because of their high rigidity. Table 2 shows the dynamic friction coefficient (dry friction) for each combination of plastics used on the inner cable side and the outer tube side.

【table】

[Table] The polyamide in the polyethylene-polyamide combination is nylon 6, the polyamide-polyester combination is 11 nylon and PBT, the polyester in the polypropylene-polyester combination is PBT, and the (polyester)-polyacetal combination is PBT. It is an acetal copolymer (trade name: Diyuracon). Table 3 shows the transmission efficiency and wear amount of the inner rope for each plastic combination, and the test conditions are as described below.

[Table] ☆ Test conditions for a helical tube made of a steel strip without a plastic sliding surface: The cable conduit specimen shown in the figure is bent into a semicircular shape, and each cable end is connected to the actuating bar through the load cell of the testing machine. The inner cable is repeatedly pushed and pulled while applying a load intermittently to the operating bar, and the load applied to the load cell is measured to determine the sliding resistance.
The operating efficiency was calculated from this. (1) Inner cable - 3mm with "7 lines 6 concentric" configuration
Plastic is coated to a thickness of 0.4mm on a core wire made of wire rope with a diameter of Configuration (3) Clearance between inner cable and outer tube - 0.6mm (4) Test temperature - Room temperature (15℃) (5) Load - 200Kg (6) Cable curvature - 180 degree direction change with curvature radius of 200mm (7 ) Push/pull stroke: 30mm (8) Number of push/pull: 44 times per minute, 50,000 times continuously (9) Measurement of wear amount: Measured after 50,000 operations (10) Transmission efficiency value: At the end of 50,000 operations However, in Comparative Example 7, the value in the steady state after the start of operation (11) Lubrication - Apply a thin layer of mineral oil at the time of startup As can be seen from Table 3, all of the test specimens with the combination of the present invention have low transmission efficiency. extremely high;
The amount of wear was also small. The comparative examples listed in the same table are made of the same type of plastic, but with the exception of Example 7, the combinations are reversed. Both the transmission efficiency and the amount of wear are inferior to the combination of the present invention. In Example 7, the plastic was worn away and the core wire was exposed. As explained above, in the cable conduit of the present invention, the inner cable is coated with thermoplastic plastic having a low coefficient of friction and high flexibility, and the outer cylindrical pipe is in sliding contact with the inner cable. The inner sliding surface is made of thermoplastic plastic selected in relation to the thermoplastic plastic applied to the inner cable, so it has a high transmission efficiency despite the large load, and the inner cable Not only does it cause little wear, but because it is a plastic-to-plastic sliding contact, it provides a good feeling during operation, and it also has excellent anti-corrosion properties, which have many practical effects. In addition, the plastic used in the present invention includes:
In addition to colorants, lubricants such as graphite, molybdenum disulfide, wax, and liquid oil can be added. Addition of these lubricants contributes to improving operating efficiency and feeling, as well as improving the wear resistance of plastic sliding parts. It also contributes to improving sexuality.

[Brief explanation of drawings]

The figure is a partially longitudinal side view showing an embodiment of the cable conduit of the present invention. DESCRIPTION OF SYMBOLS 1... Inner cable, 2... Cord wire, 3... Thermoplastic plastic, 4... Outer tube, 5... Spiral tube made of steel strip, 6... Thermoplastic plastic tube, 7... Fitting , 8... Cable end.

Claims (1)

[Claims] 1. An inner cable having a core made of steel that has a low coefficient of friction and is coated with highly flexible thermoplastic, and a flexible outer cylindrical tube whose inner sliding surface is made of thermoplastic. , the inner cable is combined in sliding contact with its inner sliding surface, and the thermoplastic plastic forming the inner sliding surface has a harderness and an elastic modulus than the thermoplastic plastic covering the inner cable. A cable conduit characterized by a high coefficient of friction between plastics in combination of less than 0.20.