JPH0610939A - Flexible cable for operation - Google Patents

Abstract

PURPOSE:To provide a flexible cable for operation which exhibits excellent frictional abrasion characteristic without interposing a lubricating agent such as grease between sliding surfaces, and allowing the distribution to a part having a small curvature radius. CONSTITUTION:A flexible cable for operation is formed of an inner cable 1 formed by stranding a plurality of aromatic polyamide resin fibers and an outer tube 2 consisting of a thermoplastic synthetic resin and the inner cable 1 is inserted into the inner hole 2a of the outer tube 2 in such a manner as to be capable of sliding in the longitudinal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible cable for operation used for remote control of bicycle brakes and various other industrial equipment.

[0002]

2. Description of the Related Art Conventionally, as a flexible cable for operation used for remote control, a steel stranded wire is used for the purpose of improving transmission efficiency, improving a feeling at the time of operation, and preventing rust. It is known that the inner cable having a plastic coating, the inner surface of the outer pipe having a plastic coating, or a plastic tube interposed between the inner cable and the outer pipe.

[0003]

In the conventional flexible cable for operation having the above-mentioned structure, since the steel twisted wire (7-wire 6-twisted concentric core) is used as the inner cable, the diameter of the inner cable itself. Becomes larger, and the diameter becomes even larger when combined with an outer tube for slidingly guiding the cable. The fact that this diameter becomes large means that in the installation of the operation cable,
Even if it becomes impossible to install the cable in a portion with a small curvature, or even if the cable becomes possible, the inner cable and the outer tube will have a high surface pressure at the curved portion, and the sliding friction resistance of the cable will be large. As a result, there arises a problem that the frictional wear characteristics of both are significantly deteriorated. In order to solve such a problem, it has been attempted to interpose a liquid lubricant such as grease on the sliding surface between the inner cable and the outer tube. There is a problem that it is scraped out from the sliding part (squeeze out) and the role as a lubricant is not fully exerted.

In view of the above situation, the inventor of the present invention is keen to obtain a flexible cable which can be installed in a portion having a small curvature in the installation without interposing a lubricant such as grease between the sliding surfaces. I did a research. As a result, focusing on aromatic polyamide resin fibers having flexibility and high strength,
It has been confirmed that a cable formed by twisting a plurality of fibers can have an extremely small diameter, and that the strength is comparable to the strength of a conventional steel stranded wire despite the small diameter. Invented. The present invention provides a flexible cable for operation, which exhibits excellent friction and wear characteristics without interposing a lubricant such as grease between sliding surfaces, and enables wiring to a portion having a small curvature. The purpose is.

[0005]

According to the present invention, the above object comprises an inner cable formed by twisting a plurality of aromatic polyamide resin fibers and a flexible outer tube made of a thermoplastic synthetic resin. The flexible cable for operation is formed by slidably inserting the inner cable into the inner hole of the outer tube in the longitudinal direction thereof. In the above structure, as the aromatic polyamide resin fiber forming the inner cable, the trade name “Kevlar” sold by DuPont or the trade name “Technora” sold by Teijin is used. Further, the thermoplastic synthetic resin forming the outer tube for slidingly guiding the inner cable is selected from polyolefin resins such as polyethylene resin and polypropylene resin, and polyacetal resin.

Further, according to the present invention, the above object is to provide a thermoplastic synthetic resin which is formed by twisting a plurality of aromatic polyamide resin fibers and has a low coefficient of friction on its outer peripheral surface and which is rich in flexibility. The inner cable includes a coated inner cable and an outer tube made of a thermoplastic synthetic resin having a higher hardness and elastic coefficient than the thermoplastic synthetic resin coated on the inner cable. The inner cable is provided in the inner hole of the outer tube. Is achieved by a flexible cable for operation, which is slidably inserted in its length direction. In the above structure, the thermoplastic synthetic resin coated on the inner cable is polytetrafluoroethylene resin (PTF).
E), polytetrafluoroethylene-propylene hexafluoride copolymer (FEP), polyolefin resin such as polyethylene resin and polypropylene resin. The thermoplastic synthetic resin forming the outer tube is selected from polyolefin resins such as polyethylene resin and polypropylene resin, polyacetal resin, and polyamide resin.

To coat the inner cable with a thermoplastic synthetic resin, extrusion molding using a crosshead die, welding by a fluidized bed dipping method, application of a synthetic resin dispersion, drying and firing are performed. A method such as forming a film to be adhered or fitting a heat-shrinkable tube is adopted. The thickness of the thermoplastic synthetic resin deposited on the inner cable is preferably 0.1 mm, especially 0.2 to 0.5 mm.

The thermoplastic synthetic resin forming the outer tube is a thermoplastic synthetic resin having a relatively higher hardness and elastic coefficient than the thermoplastic synthetic resin coated on the inner cable, and the synthetic resin is not In combination, the coefficient of dynamic friction is 0.20 or less. Table 1 shows
1 illustrates a thermoplastic synthetic resin used in the present invention.

[0009]

[Table 1]

The flexural modulus and hardness shown are PT
Each FE is set to 1 and is represented by a comparative model value.
The circles in the "where to use" column in Table 1 indicate that they are used on the inner cable side or the outer tube side. Among them, polyethylene resin and polypropylene resin are used both on the inner cable side and the outer tube side. . However, when polyethylene resin is used on the inner cable side, the thermoplastic synthetic resin used on the outer tube side has a larger flexural modulus and hardness than this, and the one shown in the lower column of Table 1 Shall be combined. When polyethylene resin is used on the outer tube side, the combination of PTFE and FEP shown on the upper side of the polyethylene resin is adopted.

Table 2 shows the dynamic friction coefficient (dry friction) in each combination of the thermoplastic synthetic resins used on the inner cable side and the outer tube side.

[0012]

[Table 2]

As described above, the thermoplastic synthetic resin forming the outer tube is a thermoplastic synthetic resin having a relatively higher hardness and elastic coefficient than the thermoplastic synthetic resin coated on the inner cable. By selecting a resin having a dynamic friction coefficient of 0.20 or less in combination with each other, it is possible to obtain a flexible cable for operation with high transmission efficiency and good feeling.

[0014]

Since the present invention has the above-mentioned structure and the inner cable can be formed to have an extremely small diameter, the outer tube for slidingly guiding the cable can also have a small diameter, and the inner cable has flexibility. Together with
Allows installation in areas with a small curvature. An inner cable made of aromatic polyamide resin fiber has a polyolefin resin such as polyethylene resin or polypropylene resin in the outer tube through which the cable is slidably guided.
By selecting polyacetal resin, both are given excellent friction and wear characteristics, and the transmission efficiency and feel at the time of operation (feeling) are improved without interposing a lubricant such as grease on the sliding surface of both. It can be measured. Furthermore, rather than the thermoplastic synthetic resin coated on the inner cable in the thermoplastic synthetic resin forming the outer tube,
By selecting thermoplastic synthetic resins having a relatively high hardness and elastic coefficient and having a dynamic friction coefficient of 0.20 or less in combination with each other, a feeling of high transmission efficiency and a feeling can be obtained. It can be further increased.

[0015]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a sectional view showing a first configuration of a flexible cable for operation of the present invention. In the figure, 1 is an inner cable obtained by using "Kevlar" manufactured by DuPont as an aromatic polyamide resin fiber, and the inner cable 1 is provided in an inner hole 2a of an outer tube 2 made of a thermoplastic synthetic resin. It is slidably inserted in the length direction.

FIG. 2 is a sectional view showing the second construction of the flexible cable for operation of the present invention. In the figure, 1 is an inner cable made of an aromatic polyamide resin fiber as in the first structure, and 3 is a thermoplastic synthetic resin film coated on the outer peripheral surface of the inner cable 1. The inner cable 1 provided with the thermoplastic synthetic resin coating 3 is slidably inserted in the inner hole 2a of the outer tube 2 made of thermoplastic synthetic resin in the longitudinal direction thereof.

FIG. 3 shows a test device for testing the transmission efficiency of the flexible cable for operation having the above-mentioned first and second configurations. The test device, test method and test device will be described below. The result of testing the transmission efficiency of the flexible cable will be described. (Test apparatus and test method) The outer tube 2 is bent with a bending radius R, and both ends of the tube 2 are fixed to the vertical frame 10 of the test apparatus. The inner cable 1 is inserted into the inner hole 2a of the tube 2, one end of the cable 1 is fixed (operated side) via the load cell X and the compression coil spring (load) S, and the other end is connected via the load cell Y. Fix it. Then, the inner cable 1 is repeatedly pulled from the operation side by the movement of the connecting rod 11 connected to the motor M and the operation arm 12 attached to the connecting rod 11. At this time, friction is generated between the inner cable 1 inserted into the inner hole 2a of the outer tube 2 and an operating resistance appears. In this test, the value recorded in the load cell X on the operated side was divided by the value recorded on the load cell Y on the operated side, and the value multiplied by 100 was taken as the transmission efficiency.

(Test conditions) Specimen I Inner cable: A cable with a diameter of 1.3 mm formed by twisting 4,000 denier Kevlar. Outer tube: A tube made of polyethylene resin and polyacetal resin with an inner diameter of 2.4 mm. Specimen II Inner cable: A cable with a diameter of 1.3 mm formed by twisting 4,000 denier Kevlar with 0.2 mm PTFE and polyethylene resin coated on the outer peripheral surface. Outer tube: A tube made of polyethylene resin and polyacetal resin with an inner diameter of 2.4 mm. The outer tube has a bending radius of 230R and a bending angle of 18
A load of 50 to 200 kg was applied by a compression coil spring at a tension rate (cycle) of 15 cpm, and the load transfer efficiency was measured at 50, 100, 150, and 200 kg, respectively. The results of the above tests are shown in Table 3.
In Table 3, the comparative product uses a steel stranded wire as the inner cable, forms the outer tube with polyethylene resin, and interposes grease between the inner cable and the outer tube.

[0019]

[Table 3]

Generally, the transmission efficiency becomes the best at the time when it becomes familiar after being operated for about tens of thousands of times, but it usually decreases gradually as the number of operations increases. As can be seen from the test results, the transmission efficiency of the flexible cable of the present invention showed stable efficiency from beginning to end, and wear of the outer tube was hardly observed. On the other hand, in the comparative product, the transmission efficiency gradually decreased as the number of tests increased and the load increased. It is presumed that this is because the grease interposed between the inner cable and the outer tube was scraped out from the sliding surface as the load increased, and the role of the grease was not fully exhibited.

[0021]

As described above, in the flexible cable for operation of the present invention, by using the aromatic polyamide resin fiber as the inner cable, the flexibility of the fiber can be fully exhibited and the inner cable can be fully utilized. Since the cable can be formed to have an extremely small diameter, the outer tube that slides and guides the cable can also have a small diameter, and in combination with the flexibility of the inner cable, the outer tube can be made to have a small curvature. Enables installation. The inner cable made of aromatic polyamide resin fiber has excellent friction and wear characteristics by selecting polyethylene resin, polyolefin resin such as polypropylene resin, or polyacetal resin for the outer tube through which the cable is slidably guided. Therefore, the transmission efficiency and the feel at the time of operation can be improved without interposing a lubricant such as grease on the sliding surfaces of both.
Further, the thermoplastic synthetic resin forming the water tube is a thermoplastic synthetic resin having a relatively higher hardness and elastic coefficient than the thermoplastic synthetic resin coated on the inner cable, and the combination of the synthetic resins with each other. In, by selecting the one whose dynamic friction coefficient is 0.20 or less,
The feeling of high transmission efficiency can be further enhanced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first configuration of a flexible cable for operation of the present invention.

FIG. 2 is a cross-sectional view showing a second configuration of the flexible cable for operation of the present invention.

FIG. 3 shows a test apparatus for testing the transmission efficiency of the flexible cable for operation of the present invention.

[Explanation of symbols]

 1 ... Inner cable 2 Outer tube 2a Inner hole 3 Thermoplastic synthetic resin coating

Claims (5)

[Claims] 1. An inner cable formed by twisting a plurality of aromatic polyamide resin fibers and a flexible outer tube made of a thermoplastic synthetic resin. The inner cable is provided in an inner hole of the outer tube. A flexible cable for operation, which is slidably inserted in the length direction. 2. The flexible cable for operation according to claim 1, wherein the thermoplastic synthetic resin forming the outer tube is selected from polyolefin resins such as polyethylene resin and polypropylene resin, and polyacetal resin. 3. An inner cable which is formed by twisting a plurality of aromatic polyamide resin fibers, and whose outer peripheral surface is coated with a thermoplastic synthetic resin having a low friction coefficient and high flexibility, and the inner cable. It is composed of an outer tube made of a thermoplastic synthetic resin having a higher hardness and elastic coefficient than the coated thermoplastic synthetic resin, and the inner cable is slidable in the length direction in the inner hole of the outer tube. A flexible cable for operation, which is characterized by being inserted. 4. The thermoplastic synthetic resin coated on the inner cable is selected from polyolefin resins such as polytetrafluoroethylene resin, polytetrafluoroethylene-propylene hexafluoride copolymer, polyethylene resin and polypropylene resin. The flexible cable for operation according to claim 3. 5. The flexible cable for operation according to claim 3, wherein the thermoplastic synthetic resin forming the outer tube is selected from polyolefin resins such as polyethylene resin and polypropylene resin, polyacetal resin, and polyamide resin.