JPH0599217A - Control cable - Google Patents

Abstract

PURPOSE:To provide a lightweight control cable having improved durability and improved operability by stranding up a plurality of steel wires each having a specified carbon content and a specified tensile wire strength and thereby forming an inner cable inserted into a conductor in the control cable for a vehicle or the like. CONSTITUTION:A wire having a specified diameter of, for example, 1.42mm, which wire is prepared by adding 0.20 weight% of chromium to a hyper-eutictoid steel having 0.80 to 0.96 weight% of carbon content, is subjected to heat treatment, thereby transforming the wire from an austenite to a pearlite to provide a steel wire 11a. This wire 11a is passed through a molten zinc bath, a water-cooling tub, a hydrochloric acid tub, and a water-cleaning tub, and then is passed through a flux tub 2. Subsequently, the wire is desiccated in a hot-air desiccation furnace 3, and is subjected to plating treatment by being passed through a plating bath 4 in which is received a Zn-Al alloy containing 4 to 6weight% of aluminium. After drawn, the resulting wires 11a are stranded up in a specified number to form an inner cable 11. This cable 11 is inserted into a conductor 12 via a liner 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control cable used in various vehicles and industrial machines.

[0002]

2. Description of the Related Art A control cable is required to have excellent performance such as operability and responsiveness, be easy to install, hard to break during use, and durable to be used safely for a long period of time. .. In order to meet such requirements, a steel wire that is strong, has little elongation and is excellent in fatigue resistance is used for the inner cord (driving force transmission cord), and the conduit has slidability, corrosion resistance, and A material having a certain degree of flexibility and rigidity is used.

As disclosed in Japanese Utility Model Publication No. 2-10331 and Japanese Patent Application Laid-Open No. 2-212615, recently, in order to mainly improve the corrosion resistance and slidability of the control cable, the inner cable is used. Is plated with zinc or a zinc-based alloy.

Further, Japanese Unexamined Patent Publication No. 62-44563 discloses a two-bath method in which a steel wire is sequentially immersed in a zinc bath and an aluminum bath in order to plate a zinc-aluminum alloy which is more excellent in corrosion resistance than zinc. Has been done.

[0005]

However, the inner cable of the conventional control cable has a tensile strength of 170 to 170.
JIS G 3506SW with a strength level of 250 kgf / mm ²
Since a steel wire such as RH62A (carbon content 0.59 to 0.66% by weight) is used, the effective cross sectional area of the cord is increased and the cable is increased in order to obtain the breaking load required for the design. It has a large diameter. For this reason, conventional cables are heavy and occupy a large space.
Therefore, it becomes difficult to attach it to the lower part of the vehicle body for driving force transmission and control. Particularly in the field of passenger cars, there is a strong demand for weight reduction of the vehicle body in recent years, and it is necessary to reduce the weight per unit length of the cable.

Further, the conventional zinc-aluminum alloy plating code by the two-bath method has a control of the surface quality of the plating.
It was difficult to obtain a stable plated surface in the longitudinal direction.

Further, in the conventional two bath method code,
The plating thickness is likely to be non-uniform, and rust occurs on the thin plated parts, resulting in poor corrosion resistance and durability.

Further, in the conventional two bath method code,
Since a brittle intermetallic compound layer is generated at the interface between the base and the plating, fatigue cracking occurs in the intermetallic compound layer in the vicinity of the interface due to repeated bending or vibration of the wire or the wire twisted wire, and disconnection occurs in a short time.

Furthermore, in the conventional two-bath method code,
Adhesion occurs between the conduit and the cord, causing stick-slip (squeaking) and deteriorating the operating feeling.

The present invention has been made to solve the above problems, and an object thereof is to provide a control cable which is light in weight and excellent in durability and operability.

[0011]

A control cable according to the present invention is a control cable in which a plated inner cable is inserted into a conduit for operation, and the inner cable is 0.80. It is characterized in that it is formed by twisting a plurality of steel wires containing carbon of up to 0.96% by weight and having a wire tensile strength of 280 to 400 kgf / mm ² .

In this case, further, the plating of the inner rope is formed by immersing the inner rope or the wire constituting the inner rope in a zinc alloy bath of a predetermined component and containing 4 to 6% by weight of aluminum. It is preferable to mainly use a Zn-Al alloy layer.

The reason for selecting the material of the inner cord in the above composition range is that the strength of the strand of the inner cord is set to 28 for the purpose of achieving high tensile strength.
To improve to a level of 0 to 400 kgf / mm ² ,
This is because it is necessary to include at least 0.80% by weight or more of carbon in the steel wire. On the other hand, if the carbon content is too high, the fatigue resistance of the cable deteriorates, so the upper limit of the carbon content was set to 0.96% by weight in consideration of the influence of the plating process and the like. Further, when chromium is arbitrarily added to strengthen the steel wire, the upper limit of the chromium content is set to 0.4% by weight for the same reason.

The reason why the lower limit of the aluminum content of the Zn-Al alloy plating is 4% by weight is that the desired corrosion resistance cannot be obtained with an aluminum content below this value.

On the other hand, the reason why the upper limit of the aluminum content of the Zn-Al alloy plating is set to 6% by weight is that the desired fatigue resistance cannot be obtained when the aluminum content exceeds this value.

Further, by setting the Al content in the alloy to 4 to 6% by weight, the fluidity of the molten metal in the bath becomes good, so that the plating surface becomes beautiful and Zn-
Since the melting point of the Al alloy is low, it is suitable for plating steel wire as a strength member, can suppress erosion in the bath of equipment tools for immersion, and can reduce the occurrence of dross. There are advantages.

The reason why the Zn-Al alloy plating is formed by a so-called "one-bath method" in which the inner wires or the wires constituting the inner wires are immersed and passed through a single molten metal bath is as follows. Secondly, in order to prevent the brittle intermetallic compound layer from growing and developing at the boundary with the plating layer, secondly, to improve the surface characteristics of the plating. The first reason is that the intermetallic compound at the boundary between the wire base metal and the plating layer has the property of being hard and brittle. Therefore, when this intermetallic compound layer grows and develops to a thickness that cannot be ignored, this causes fatigue cracking. This is because the fatigue resistance of the cable is remarkably lowered from the starting point. The second reason is that the plating formed by the one-bath method has less uneven thickness and has a smooth surface, so that it is excellent in operability and has improved corrosion resistance and fatigue resistance.

By controlling the cooling conditions immediately after plating to a desired rate and temperature, the plating layer is mixed in which a pearlite phase with advanced granulation exists in the interstices of the dendrite structure of α phase or β phase. It can be an organization. Such a mixed structure of dendrite / pearlite phase is particularly excellent in fatigue resistance and contributes greatly to the improvement of cable durability.

On the other hand, in the pearlite structure in which the α-phase and β-phase thin plate layers are alternately arranged, fatigue cracks easily propagate along the crystal grain boundaries, and the fatigue resistance is poor. In particular, in the sharp pearlite structure in which the crystal grain boundaries are directly connected to the substrate, fatigue cracks propagate to the surface along the crystal grain boundaries of the thin plate-like structure, leading to fatigue fracture in a short time.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Heat Treatment of Steel Wire] Hypereutectoid steels having carbon contents of 0.86% by weight, 0.92% by weight and 0.96% by weight, respectively, added with 0.20% by weight of chromium and having a diameter of 1.42 mm. After heating the three types of wire rods in the austenite region, the time from the maximum heating temperature to passing the A ₁ transformation point is 0.8.
The structure of each wire is transformed from austenite to pearlite by accelerating cooling at a rate of not more than a second.

[Steel Wire Plating Processing] The steel wire plating processing will be described with reference to FIG. The steel wire 11a heat-treated as described above is dipped and passed in a molten lead bath (not shown) (about 400 ° C.), and further dipped and passed in a water cooling tank, a hydrochloric acid tank, and a water washing tank (neither is shown) to degrease the surface Wash. After the degreasing cleaning treatment, a predetermined amount of flux is attached to the steel wire 11a in the flux tank 2 and dried in the hot air drying furnace 3.

After drying, the steel wire 11a is dipped and passed through the plating bath 4. The plating bath 4 contains a molten Zn—Al alloy. The molten Zn-Al alloy is adjusted to have an aluminum content in the range of 5 ± 1% by weight.

A roll box 5 is provided at a position where the steel wire 11a is transferred from horizontal to vertical by a roll 5 in the bath and the steel wire 11a is pulled up from the bath 4. A non-oxidizing gas 7 is introduced into the seal box 6, and the excess Zn—Al alloy adhering to the steel wire 11a is squeezed out under a non-oxidizing atmosphere to adjust the plating layer to an appropriate thickness. Further, water is sprayed onto the steel wire 11a by the water cooling nozzle 8 to water-cool the steel wire 11a. The temperature of the cooling water is adjusted to 45 ± 2 ° C., and the steel wire 11a is cooled at a desired cooling rate.

In this way, by controlling the cooling conditions immediately after plating, dendritic primary crystals of α phase or β phase are crystallized, and the gaps between them are formed by a pearlite structure in which granulation has progressed. The plating layer structure was buried. Such a dendrite / pearlite phase mixed structure is particularly excellent in fatigue resistance and corrosion resistance, and contributes greatly to the improvement of cable durability.

[Drawing] After the plating treatment, the steel wire 11a was drawn at a surface reduction rate of 96.5%. At this time, it is necessary to reduce the surface tensile residual stress of the wire generated during wire drawing for the purpose of ensuring the workability for obtaining the desired strength. That is, in the middle of wire drawing, the steel wire 11a is passed through a so-called leveling roll in which a plurality of small-diameter rollers are arranged in a zigzag manner, and a small bending strain is applied to the steel wire 11a to improve the twisting value.

As in this example, since the surface properties of the plating formed by the one-bath method are good, the effect of wire drawing on the fatigue resistance is not recognized. On the other hand, since the surface properties of the plating formed by the conventional two-bath method are poor, the uneven plating structure bites into the iron base during wire drawing, and the fatigue resistance is significantly reduced.

[Manufacture of Inner Line] A case will be described in which the inner line 11 is manufactured by twisting together steel wires 11a having a plating adhesion amount of about 350 g per 1 m ² .

Steel wire 11 from seven bobbins of the tubular stranded wire machine
The rotor is rotated while supplying a toward the voices, respectively, to manufacture a 7-strand strand.

Further, the 7-strand strand is wound around each bobbin of the cylindrical stranding machine, and the rotor is rotated while supplying the 7-strand strand 7 toward the voice, as shown in FIG. 7 × 7 inner cords 11 having a cross section were manufactured. The twist pitch at this time was 28 to 30 mm.

The average diameter of the inner cable 11 thus manufactured is 4.0 mm.

[Manufacture of Conduit] With reference to FIG.
The production of No. 2 will be described.

A liner 13 is provided on the inner surface of the conduit 12 to ensure smooth sliding with the inner cable 11. The liner 13 is made of a soft synthetic resin having good surface properties and excellent wear resistance.

A steel wire strand 14 is provided on the outer periphery of the liner 13.
Wrap around. The steel wire strand 14 is formed by twisting together seven steel wires having a predetermined wire diameter, and has the role of ensuring the rigidity of the conduit 12 and enhancing the responsiveness of the control cable. Further, since it is necessary to secure a certain degree of flexibility, the strength balance of the steel wire strand 14 with respect to the inner cord 11 is considered.

Further, the outer surface of the steel wire strand 14 as a rigid member is covered with a jacket 15. The jacket 15 is made of hard synthetic resin.

The control cable 10 thus produced has an average diameter of 12 mm and an average weight per 1 m of length of 0.3 kg.

Next, the fatigue test of the inner cable 11 will be described with reference to FIG.

Three posts 22 are erected on a pedestal 21 of the fatigue tester 20, and the inner rope 11 is a roller 23 of the posts 22.
It is supported by. One end of the inner cable 11 is fixed to the post 24, and the other end is held by a chuck 25 urged by a spring 26. The weight of the weight 27 acts on the inner cable 11 as a tension via the spring 26.

The central post 22 is connected to the arm 29 of the reciprocating crank mechanism. When the disc 28 is rotated, the central post 22 moves up and down, so that the inner cord 11 is regularly vibrated.

FIG. 5 is a graph showing the results of examining the correlation between the aluminum content of the plating on the horizontal axis and the fatigue resistance index on the vertical axis. Amplitude ± 10
The test conditions were that the reciprocating vibration of about 80,000 times was given to the inner cable 11 as mm. Here, the fatigue resistance index is an index when the result of the 7 × 7 inner cord without plating is 100. Those with a fatigue resistance index of more than 80 are regarded as acceptable. As is clear from the figure, when the aluminum content in the plating is 6% by weight or less, the index exceeds 80.

In FIG. 6, the horizontal axis represents the aluminum content, and the vertical axis represents the red rust generation time in the salt spray test.
It is a graph which shows the result of having investigated the correlation of both.
Those with a red rust generation time of more than 200 hours are regarded as acceptable.
As is clear from the figure, when the aluminum content in the plating was 4% by weight or more, the red rust generation time exceeded 200 hours.

Table 1 shows Examples 1 to 4 and Comparative Example 1
Results of comparing various data under various conditions as shown in FIGS. The weight ratio was based on Comparative Example 1. As is clear from Table 1, in each of Examples 1 to 4, it was possible to achieve a significant weight reduction of 42 to 60% as compared with the conventional one without impairing the fatigue resistance and stick-slip characteristics.

The cold drawing (drawing) process of the inner cable and the plating process may be replaced with each other. That is, in the above embodiment, the case where the wire drawing process is performed after the plating process has been described, but the plating process may be performed after the wire drawing process.

Further, in the above embodiment, a 7 × 7 inner cable is cabled.
However, the present invention is not limited to this, and it is of course possible to employ an inner cable having another configuration.

As shown in FIG. 7, the structure of the inner cable is 7 × 7 ×.
When set to 7, the cable becomes stronger.

As shown in FIG. 8, the structure of the inner cable is 7 × 19.
May be

As shown in FIG. 9, the structure of the inner cable is 7 × W.
It may be (19).

[0048]

[Table 1]

[0049]

According to the present invention, it is possible to provide a lightweight control cable which is excellent in durability and operability and has high tensile strength. In particular, when the inner wire is plated by the one-bath method and the cooling rate is controlled, the intermetallic compound layer at the boundary between the wire base metal and the plated layer does not substantially grow and develop, and the plating has excellent fatigue resistance. You can get a tissue. For this reason, the controller is compact, light, and hard to break.
A package can be obtained, and the demand for weight reduction of the vehicle can be sufficiently satisfied.

The Al content in the plated alloy is 4 to 6% by weight.
By this, the fluidity of the molten metal in the bath becomes good and the plating surface becomes beautiful. This can improve the corrosion resistance and fatigue resistance of the cable.

Further, since the melting point of the plating alloy is lowered by setting the Al content to 4 to 6% by weight, it is suitable for the plating of steel wire as a strength member, and is eroded in the bath of the equipment tool for immersion. Can be suppressed. Further, there is an advantage that the generation of dross is reduced.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a control cable according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the inner cable of the control cable according to the embodiment.

FIG. 3 is a schematic sectional view showing an outline of plating treatment equipment for inner cable.

FIG. 4 is a schematic diagram showing an outline of a fatigue resistance test device for inner cords.

FIG. 5 is a graph showing the results of fatigue resistance test.

FIG. 6 is a graph showing the results of a salt spray test.

FIG. 7 is a cross-sectional view of an inner cable according to another embodiment.

FIG. 8 is a cross-sectional view of an inner cable of another embodiment.

FIG. 9 is a cross-sectional view of an inner cable according to another embodiment.

[Explanation of symbols]

10; control cable, 11; inner cable, 12; conduit, 13; liner, 14; strand (rigid member),
15; Jacket (covering member)

Claims (3)

[Claims] 1. A control cable in which a plated inner cord is inserted into a conduit for operation, wherein the inner cord is
A control cable, which is formed by twisting a plurality of steel wires containing 0.80 to 0.96% by weight of carbon and having a wire tensile strength of 280 to 400 kgf / mm ² . 2. The plating of the inner cord is formed by immersing the inner cord or a wire constituting the inner cord in a zinc alloy bath containing a predetermined component, and Zn-containing 4 to 6% by weight of aluminum.
The control cable according to claim 1, which is mainly composed of an Al alloy layer. 3. The plating of the inner cord is composed of a Zn--Al alloy mainly composed of a mixed structure in which a pearlite phase with advanced granulation exists in the spaces between the α-phase or β-phase dendrite structures. The control cable according to claim 1, which is characterized in that.