JPH01158209A - Control cable - Google Patents

Abstract

PURPOSE:To aim at durability and load efficiency of a control cable by forming an inner coat and a liner on the inner circumference of a conduit by polyamide resin composition and polybuthylene terephthalate resin composition having respective specific valves of bending stress and thermal deformation temperature. CONSTITUTION:An inner coat 3 on the outer circumference of an inner cable 1 in formed by polyamide resin composition having stress of 455kPa and a thermal deformation temperature of 180 deg.C or more and a liner 4 on the inner circumference of a conduit 2 is formed by polybuthylene terephthalate resin composition of 1,820kPa and 50-200 deg.C. Accordingly, its durability and load efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control cable. More specifically, the present invention relates to a control cable that has significantly improved durability and load efficiency.

[Conventional technology] Conventionally, in order to improve transmission efficiency, a plastic coating (hereinafter referred to as "inner coat") is applied to the outer periphery of the inner cable of a control cable, and a plastic tube (hereinafter referred to as "liner") is placed inside the conduit. ) is used.

For example, JP-A-60-231009 discloses a control cable in which the inch coat is made of polytetrafluoroethylene (hereinafter referred to as PTPE) and the liner is made of polyoxymethylene (hereinafter referred to as POM).
A control cable is shown in which the inner coat is made of nylon 11 and the liner is made of polybutylene terephthalate (hereinafter referred to as PBT). All of these have the effect of reducing wear because the coefficient of friction between the inner coat and the plastic liner is small.

[Problems to be solved by the invention] Recently, however, as machines that use control cables have become more sophisticated and more compact, the load to be borne has increased.
The conditions for their use are becoming increasingly severe, such as rising environmental temperatures and decreasing curvature of the wiring shape.

As a result, the control cable generates a lot of heat during use, resulting in severe wear of the inner coat and liner, and even the conventional control cable does not have sufficient durability or load efficiency.

In view of the above circumstances, the present invention aims to provide a control cable having higher durability and load efficiency.

[Means for Solving the Problem] The control cable of the present invention includes an inner cable and a conduit for slidably guiding the inner cable, and the inner coat on the outer periphery of the inner cable is bent in accordance with ASTM D-648. It is formed from a polyamide resin composition with a heat distortion temperature of 180°C or higher when measured at a stress of 455 kPa (4,8 kgf/ad), and the liner on the inner circumference of the conduit has a bending stress of 1820 kPa (18,8 kgf') in accordance with ASTM D-848.
/cd) is formed from a polybutylene terephthalate resin composition having a heat distortion temperature of 50 to 200°C.

As the polyamide resin composition (hereinafter referred to as PA resin composition) which is the material of the inner coat, nylon 6, nylon 6B, nylon 6.■O16iroilon 62, nylon 4.6, etc. are used. The PA resin composition may be composed of only PA, or may be composed of PA with a small amount of lubricating oil such as silicone oil added to improve sliding properties.

The polybutylene terephthalate resin composition (hereinafter referred to as PBT resin composition) which is the material of the liner may be made of PBT alone, or may be used in combination with fine fibrous or granular filler.

By incorporating such a filler, the heat distortion temperature can be increased and durability can be further improved. A particularly preferred filler is potassium titanate whiskers. Although the effect of improving durability can be recognized even when the proportion of potassium titanate whiskers is less than 1%, it is most preferable that the proportion is from 1.1 to 30% by weight because the effect of improving durability is remarkable. If it exceeds 30% by weight, no further improvement in heat deformation temperature is observed and flexibility is significantly reduced.

Therefore, if the conduit is bent, the conduit will easily break, which is not preferable.

Note that an organic filler such as aramid fiber may be blended instead of the inorganic filler such as the potassium titanate whisker. In that case, the blending ratio is preferably 1 to 30% by weight.

The "heat distortion temperature" of the inner coat material and liner material is
American Society for Testing and Materials
y of' Testing Materials) ASTM standard D-848rstandard Te
5t Method f'or DEFLECTION
TEMPERATURE OF PLASTI・C8U
NDERPLEXURAL LOAD J
) The above "bending stress" was measured according to ASTM
It means the bending stress applied to a test piece as specified in D-648.

In addition, the thermal deformation temperature of the inner coat material is determined by bending stress of 455k.
The measurement is made in Pa because the inner coat covers and binds the inner cables made of steel wires with high surface hardness and requires flexibility, so the bending stress is 1820kP.
This is because adding a would result in too high a load.

The heat deformation temperature of the inner coat material must be 180°C or higher, and if it is lower than 180°C, it cannot be used because the durability is low.

The heat distortion temperature of the liner material must be between 50 and 200°C; if it is less than 50°C, the durability will be significantly reduced and
At temperatures above 00°C, the flexibility decreases significantly, and neither can be used.

In addition, when PBT is copolymerized with a third component other than terephthalic acid and butanediol that form PBT, generally,
A PBT copolymer with a reduced heat distortion temperature of less than 50° C. cannot be used as a liner material because its durability is extremely low.

[Function] The control cable of the present invention has much higher durability and good load efficiency than conventional control cables.

Such performance was achieved by combining specific materials with specific requirements for the inner coat and liner. That is, as a result of intensive research by the present inventors, the inner coat is made of PA.
A resin composition is used for the liner, and a PBT resin composition is used for the liner.
Surprisingly, by limiting the temperature to temperatures above 80°C (the latter being 50 to 200°C), they have achieved high durability that is far beyond any conventional control cable.

The reason for this is that PA resin compositions with a heat distortion temperature of 180°C or higher have a high degree of flexibility and wear resistance;
The ~200°C PBT resin composition has a high degree of abrasion resistance, and when they are combined as an inner coat and liner, their respective physical properties significantly reduce wear when the inner coat is slid within the liner. It is thought that this is due to such an interaction.

The high durability of the present invention cannot be achieved simply by combining specific materials, but can only be achieved by limiting the heat distortion temperature to the above range. This will be made clear in the description of the embodiments.

[Example] Next, the control of the present invention will be explained based on an example.

Figure 1 is a partially cutaway perspective view showing an embodiment of the control cable of the present invention, Figure 2 is an explanatory diagram of a measuring device for measuring the performance of the control cable of the present invention, and Figure 3 is a load efficiency test and A graph showing the load applied in the durability test, and FIG. 4 is a graph showing the measurement results of durability and load efficiency.

The present invention can be applied to any control cable as long as the inner coat (3) is formed on the outer circumference of the inner cable (1) and the liner (4) is formed on the inner circumference of the conduit (2). .

Next, an example will be given and explained.

Example 1 In Fig. 1, (1) is the inner cable, (2) is the conduit, and (3) is the inner cable.
is an inner coat, and (4) is a liner. Inner cable (1)
makes one strand by twisting seven steel cables together,
It is a wire lobe with a 7x7 structure made by twisting seven strands together, and has an outer diameter of 2.5 cm. Conduit (2
) is one rectangular cross section (thickness 1,00mm5 width 2.3
An armor layer (5) formed by closely winding steel strips of >3 mm in a medium-like manner to form a tubular shape (outer diameter 8.91111 mm, inner diameter 4.82 mm), and a composite coated outer circumference with a thickness of 0.55 mm. It is composed of a protective layer (6) of resin (polypropylene). The inner coat (3) is made of the material shown in Table 1 and has the heat distortion temperature shown in Table 2, and has a thickness of 0.3av.
The outer periphery of the inner cable (1) is covered with the inner cable (1). The liner (4) is made of the material shown in Table 1 and has the heat deformation temperature shown in Table 2, and the inner diameter of the conduit (2) is 3.7 mm and the outer diameter is 4.6 mm.
1.

The outer circumference (3.1 mm) of the inner coat (3) and the liner (
4) There is a diameter of 0.8m between the inner circumferences (3, 7a+g+)
There is a gap of m. A lubricant (7) of silicone grease is applied to the outer peripheral surface of the inner coat (3) at a ratio of Ig/+.

Examples 2 to 4 Control cables were made in the same manner as in Example 1, except that the inner coat (3) and liner (4) were made of the materials shown in Table 1 and had the heat distortion temperatures shown in Table 2. ,Ta.

Comparative Examples 1 to 4 Control cables were produced in the same manner as in Example 1, except that the inner coat (3) and liner (4) were made of the materials shown in Table 1 and had the heat distortion temperatures shown in Table 2. .

Comparative Example 1 and Comparative Example 2 are conventional examples of JP-A-60
Comparative Example 3.4 was made using the material described in Japanese Patent Publication No. 231009, and the materials used in Comparative Example 3.4 were the same as those of the present invention, but outside the range of heat distortion temperature conditions.

Inner coats of Examples 1 to 4 and Comparative Examples 1 to 4 (3
) and the material of the liner (4) are shown in Table 1, and the heat distortion temperature of each material is shown in Table 2.

[Left below] Table 1 [Note 1] PTFE: Polytetrafluoroethylene nylon 11: ω-aminoundecanoic acid condensation polymer PO
M: Polyoxymethylene [Note 2] As a silicone oil, the viscosity is 25,000.
Uses cSt polydimethylsiloxane (dimethylsilicone oil).

[Note 3] Potassium titanate whiskers have a diameter of 0.
．． Use whiskers of 2 to 0.5 barrels and 10 to 20 barrels in length.

[Note 4] PBT used is a 0-chlorophenol solution with an intrinsic viscosity of 1.40 dl/g measured at 25°C. Nylon 6B has a relative viscosity of 2.8 measured using the sulfuric acid solution method based on JIS K6810.

[Note 5] Hytrel 7247 is a PBT-based copolymer obtained by polycondensation of terephthalic acid, butanediol, and polytetramethylene glycol.

Table 2 A load efficiency test and a durability test were conducted on the above examples and comparative examples.

The test apparatus will be explained based on FIG. Constant temperature box 01)
The bending radius of the inner cable (1) is 5011% and the bending angle is 1.
A control cable of the test piece was attached to the test piece, which was curved in a semicircular shape at an angle of 80 degrees. A lever 02) is attached to the input side end of the inner cable (1), and a spring for applying a load is attached to the load side end. In addition, there is a load cell 04) on the input side of the inner cable (1).
A load cell is attached to the middle of the load side. The lever 02) was swung as shown by the arrow (A) and reciprocated at a speed of 60 times per minute, with one reciprocation being one reciprocation. Two types of springs were combined so that the load in one reciprocation was as shown in Figure 3. That is, the stroke is θ~19o
It increases linearly with a steep slope up to i, and the stroke 19a+
A load of 54.5 kgf is applied at a+, and the stroke is 19
~36.5am, the load increases linearly on a gentle slope, and a load of 85kgf is applied at strokes 3B and 5a+i. The temperature inside thermostatic box 01) was maintained at 80°C.

Load efficiency is W/F xl when load side output is 60kgf
It is represented by oo. Here, F) is the measured value of the input side load cell 04), and (v) is the measured value of the load side load cell. The service life is the lever 02 until the inner coat (3) and liner (4) wear out and the strands of the inner cable (1) and the armor layer (5) of the conduit (2) become visible on the surface.
) is expressed as the number of oscillations.

Figure 4 shows the measurement results of load efficiency and service life.

As is clear from the figure, Comparative Example 1 wears quickly and has significantly poor durability, and the load efficiency also quickly decreases. Also, comparative example 2
-4 has a service life of approximately 1.6 to 2 million times, and is not very durable, and its load efficiency is also somewhat low.

On the other hand, in Example 1.2 of the present invention, the service life is 300.
The number of times exceeded 1,000,000, and Example 3.4 also achieved approximately 2,500,000 times. Therefore, it shows a much higher value than Comparative Example 1.2.

In addition, the load efficiency maintains a high efficiency of approximately 92 to 93% until the end of its service life. Therefore, it can be seen that the control cable of the present invention has significantly higher performance than the conventional example in terms of durability and load efficiency.

In Comparative Example 3, the main materials of the inner coat (3) and liner (4) are the same as those of the present invention, but the heat distortion temperature of the inner coat (3) is lower than 180° C., which is the condition of the present invention. The durability of Comparative Example 3 has not reached 2 million times. In Comparative Example 4, the main materials of the inner coat (3) and liner (4) were the same as those of the present invention, but the heat distortion temperature of the liner (4) did not reach 50° C., which is the condition of the present invention. Comparative Example 4 has a service life of only around 1.8 million times.

From the above, inner coat (3) and liner (4)
) It can be seen that even if the main material is the same, if the heat distortion temperature conditions are different, high durability cannot be achieved.

In the present invention, the size of the control cable and the materials of the inner cable (1) and the conduit (2) are not particularly limited. However, in consideration of breakage of the inner cable due to fatigue, it is preferable to satisfy the condition σ/(σb+σ1)>2 to 3 depending on the bending radius of the cable and the load under the test conditions. However, σ: average tensile strength of the inner cable strands (kgf/nvA) σ,: average bending stress of the inner cable strands (kgf/mff1) σ,: average tensile stress of the strands of the inner cable (kgf'/m()) As long as the control cable of the present invention satisfies the conditions specified in the claims,
Although it can demonstrate the above durability, it also has an inner coat.
) It goes without saying that if a lubricant such as graphite, PTFE, or lubricating oil is added to (3) or liner (4), the load efficiency will be further improved.

The thickness of the inner coat and the liner in the present invention are preferably thicker in order to improve durability, but as far as the wiring shape in the test apparatus shown in FIG. 3 is concerned, Example 1
A thickness of ~4 is almost the limit. As for the thickness of the inner coat and the thickness of the liner, there are optimum values for each size of the control cable, which can be determined by design calculations or experimentally.

[Effects of the Invention] The control cable of the present invention has significantly improved fire resistance and high load efficiency compared to conventional cables.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway perspective view showing an embodiment of the control cable of the present invention, Figure 2 is an explanatory diagram of a measuring device for measuring the performance of the control cable of the present invention, and Figure 3 is a load efficiency test. and a graph showing the load applied in the durability test, and FIG. 4 is a graph showing the measurement results of durability and load efficiency. (Main symbols in the drawing) (1): Inner cable (2): Conduit (3): Inner coat (4) Niliner medium 1 time

Claims (1)

[Claims] 1. Consisting of an inner cable and a conduit for slidably guiding the inner cable, the inner coat around the outer circumference of the inner cable conforms to ASTM D-46.
8, bending stress 455kPa (4.6kg^f
The liner on the inner circumference of the conduit has a bending stress of 1820 k in accordance with ASTM D-648.
A control cable formed from a polybutylene terephthalate resin composition having a heat distortion temperature of 50 to 200°C as measured at Pa (18.6 kg^f/cm^2). 2 The inner coat has a bending stress of 455 kPa (4.6 kg/cm^2) according to ASTM D-468.
2. The control cable according to claim 1, wherein the control cable is a polyhexamethylene adipamide resin composition having a heat distortion temperature of 180° C. or higher as measured at . 3. The control cable according to claim 1, wherein the liner is formed from a polybutylene terephthalate resin composition containing 1 to 30% by weight of potassium titanate whiskers.