JPH02142017A - Flexible conductor with bending and vibration resistance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flexible conductor having a large current capacity and excellent bending resistance and vibration resistance.

[Conventional technology and problems to be solved] For example, in the power supply lead wire of a spot welding machine using an industrial robot, an extremely large current is passed through each time welding, and an impact (electrodynamic) Photography occurs. Furthermore, each time the robot operates, the lead wire is swung around and repeatedly bent. The leads used in this manner are therefore flexible conductors.

This flexible conductor is usually made by twisting together strands of mild steel wire, concentrically twisting the assembled strands to make a compound strand (child twist), and further concentrically twisting the compound strand to make a compound strand. It consists of a wire, and has a cross-sectional structure as shown in FIG. 4, for example.

Observing the use of the flexible conductor, the strands of the compound stranded wire are rubbed at the parts where they touch each other while being subjected to repeated bending and impact, causing wear and tear. When a part of the strands breaks, the resistance of the conductor increases, and that part overheats, making it even more likely to break, and the vicious cycle repeats, causing the wire to break.

This disconnection occurs in the outermost child twist (2c') of the compound twist.
This is most noticeable at the part where the IW (2b') in the outermost layer and the child twist (2b') in the lower layer are in contact with each other, and the wire breakage is particularly noticeable in the child IW (2b') in the lower layer than in the child twist (2c') in the outermost layer. According to the durability test of the complex stranded wire shown in Fig. 4, using pure annealed copper wire as the strands of each child m (2a') (2b') (2c'),
Lower layer child twist (2b') in contact with outermost layer child twist (2c')
Among these, the breakage of the strands of the collective stranded wires (Id') in the outer layer portion was particularly noticeable.

Therefore, when using this type of flexible conductor,
It is desired to improve the bending resistance and vibration resistance under heating to prevent the above-mentioned wire breakage.

Therefore, based on the above observation results, it was proposed that the twisting directions of the outermost layer and the lower layer are the same so that the wires touching each other do not cross.
No. 06), although in this case wire breakage was less likely to occur compared to conventional products in which the strands crossed, a fully satisfactory effect could not be obtained.

Therefore, the present inventors aimed to prevent the above-mentioned wear-out and disconnection.
Furthermore, in the process of researching and examining various types of wires, we found that the friction coefficient is smaller when wires of different metals are in contact with each other than when wires of the same metal, especially pure annealed copper wires, are in contact with each other. It has been found that the occurrence of wear and disconnection due to rubbing etc. is significantly reduced.

Based on this, a child twist using pure copper strands and a child twist using a separate copper alloy strand are brought into contact, and bending,
When a wear test was conducted under photographic conditions, it was found that the wear resistance was greatly improved.

[Means for Solving the Problems] The present invention has been made based on the above findings, and the present invention is based on the above-mentioned findings. We decided to use a softened wire made of the following copper alloy, which has good electrical conductivity and excellent mechanical properties such as heat resistance and bending resistance, for the lower layer child-twisted wires. The present invention provides a flexible conductor that has improved vibration resistance and is extremely effective in preventing wire breakage due to wear and tear.

That is, the first aspect of the present invention is, in particular, in a flexible conductor in which a composite stranded wire obtained by concentrically twisting agglomerated stranded wires is used as a child twist, and the child twist is further concentrically twisted to form a compound compound strand, the outermost layer thereof is configured. The strands of the child twist are made of pure annealed copper wire, and the strands of the child twist of the lower layer in contact with the child twist of the outermost layer contain Fe and Ag, and the content thereof is Fe: 0.1 to 2.5 Weight %Ag: 0.
03 to 0.5% by weight, and the remainder is copper.

The second aspect of the present invention is that the wire breakage of the collective stranded wires in the outer layer is remarkable among the lower layer child twists in contact with the outermost layer child twists, and the cost of the copper alloy is taken into account. In a flexible conductor made of the same compound twisted wire as described above, the wires of the child twist constituting the outermost layer are pure annealed copper wire, and the outer layer portion of the child twist of the lower layer in contact with the child twist of the outermost layer is made of pure annealed copper wire. It is characterized in that the strands of the assembled stranded wires are made of the above-mentioned softened copper alloy wires, and the other strands of the assembled stranded wires are made of pure annealed copper wires.

In the copper alloy used in the above invention, the Fe content is 0.1
~2.5% by weight is because if it is less than 0.1% by weight, effects such as repeated bending strength, tensile strength, and heat resistance will be reduced, while if it exceeds 2.5% by weight, electrical conductivity (thermal conductivity) will decrease.
This is because the decrease in Also to 8 content 0.0
The reason why it is set at 3 to 0.5% by weight is that if it is less than 0.03il%, the effects such as cyclic bending strength, tensile strength, and heat resistance will decrease, while if it exceeds 0.5% by weight, the electrical conductivity will decrease. This is because castability also deteriorates.

[Function] According to the above-described first flexible conductor of the present invention, the outermost layer of the child-twisted strands of the composite stranded wire is pure annealed copper wire, and the lower layer of the child-twisted strands in contact with this are the above-mentioned. By using a copper alloy made of copper alloy, dissimilar metal wires come into contact with each other in the contact area between the outermost layer of child twist and the child twist of the lower layer, where wear and breakage of the strands is noticeable. The coefficient of friction is reduced, the wear resistance is greatly improved, and wire breakage due to wear is extremely difficult to occur.
Coupled with the fact that we used a copper alloy softened wire, which has good electrical conductivity and excellent mechanical properties such as heat resistance, repeated bending, and tensile strength, for the child twisted wire (first layer), It enhances the effect of preventing wire breakage due to wear and tear, and greatly reduces the incidence of wire breakage.

Further, according to the second invention, among the child twists in the lower layer that are in contact with the child twists in the outermost layer, the strands of the collective stranded wire in the outer layer portion where wear and breakage is most likely to occur are the softened wires of the copper alloy, and Since the strands of the assembled stranded wire are made of pure annealed copper wire, the contact area between this child twist and the child twist in the outermost layer is a contact between different metal wires, and as mentioned above, frictional disconnection is unlikely to occur at this part. In addition, dissimilar metal wires come into contact with each other at the contact portion between the stranded wires in the outer layer portion and the stranded wires in the central portion, making it difficult for wear and wire breakage to occur at this contact portion. Moreover, since the strands of the stranded wires other than the outer layer portion are made of pure annealed copper wire, there is no problem with the flexibility of the entire flexible conductor.

[Example] Next, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a cross-sectional structure of a flexible conductor made of a complex twisted wire according to the first aspect of the present invention. In the figure, (1) is a collective stranded wire made by collectively twisting 26 strands with a diameter of 0126 mm, (
2) is a composite stranded wire obtained by concentrically twisting seven of the above-mentioned stranded wires (1). The complex twisted flexible conductor (3) has one compound twisted wire (2) as a child m (2a) in the center layer, and six compound twisted wires (2b) in the first layer on the outside. The wire (2) is further concentrically twisted with 12 composite twisted wires (2) each arranged as a second Nth child 1'1 (2c) on the outside.

The child twists (2c) of the first layer and the child twists (2b) of the outermost layer may be concentrically twisted in opposite directions as in the conventional case, or the child twists (2c) (2b) of both layers may be twisted in the same direction. It may be twisted concentrically. In the latter case, child twist (2c) (2b)
The strands of the wires come into contact with each other along the twisting direction, and there is no strong local contact unlike in conventional flexible conductors where the strands cross and touch each other. The effect of preventing wire breakage due to wear becomes even greater.

In the flexible conductor having the above structure, the outermost layer child twist (
Pure annealed copper wire is used as the wire constituting 2c), and this twisted wire (2c) is
F
e and Ag at the above-mentioned mixing ratios, that is, Fe
A copper alloy containing: 0.5% by weight and 2% by weight of A and [:0° was used.

Therefore, the child of the outermost layer and its lower layer t'14 (2c)
The contact area between the (211) metal wires is the contact between different metal wires, and the friction coefficient of this area is small, making it difficult for wire breakage to occur due to wear. Note that in the drawings, only the portions using the softened wire of the copper alloy are shown with hatching.

The strands constituting the center layer child twist (2a) could be made of the copper alloy as in the first layer child twist (2b), but as a result of a durability test, the center layer child twist t'ff1 It is better to use pure copper-resistant copper wire for the strands of (2a), since the center layer and the first layer's child twist (2a)
) (2b) The contact part is a contact between dissimilar metal wires, which reduces wear and breakage of the strands, does not reduce flexibility, and is made of copper alloy, which is more expensive than annealed copper wire. This method is more suitable for practical use because the amount of used is reduced.

FIG. 2 shows a cross-sectional structure of a second flexible conductor of the present invention, and in a flexible conductor made of a compound twisted wire similar to the above,
Among the child twists (2b) of the composite strands (2) of the lower N (first FI) that are in contact with the child twists (2c) of the outermost layer, the strands of the collective strands (ld) in the outer layer part where wear and breakage easily occur are The above-mentioned softened copper alloy wire is used, and the other aggregated stranded wires, in the case of the figure, the strands of the aggregated stranded wire (le) in the center part are pure annealed copper wires similar to the outermost layer child strands (2c). In the drawings, only the part of the stranded wire using the softened copper alloy wire is shown with hatching.

In this case as well, dissimilar metal wires come into contact with each other in the contact area between the outermost layer of child twist (2c) and the child twist (2b) of the lower layer, so wear and tear breakage is less likely to occur in this area. Also, the amount of copper alloy used is small.

Regarding the child twist (2a) in the center layer, there are cases where the wire is made of the above-mentioned softened copper alloy as described above, and cases where it is made of pure annealed copper wire.

The above flexible conductor (3) has connection terminals <4) fixed to both ends, as shown in the conventional case, for example, and an insulating outer iK (5) is placed between both terminals. It is held watertight to allow cooling water to flow through it, and is used as lead wires for power supply to welding robots.

(Test to confirm effectiveness) The flexible conductor of the example shown in Fig. 1 above, the flexible conductor of the example shown in Fig. 2, and the flexible conductor shown in Fig. 4 (all strands are pure annealed copper wire) For each of the outermost layer (A), which is concentrically twisted with the twisting directions of the 27th layer and the layer below (Fig. 1) intersecting, and concentrically twisted in the same direction. The twisted material (B) was tested on a welding robot under the same conditions, and the number of spot welding cycles was compared, and the state of wear and breakage was observed, and the following results were obtained.

Sample Twisting direction Spot count Example of Figure 1 A 350,000 to 450,000 times 8
550,000 times or more Example of Figure 2 A 250,000 to 350,000 times Same B
450,000 times or more Fig. 4 (Conventional product) A Approximately 100,000 times Fig. 4 (Comparative example) B 250,000 to 350,000 times As shown in the table above, the conventional product wears out at about 10,000 spots and breaks. The ratio was as high as 25% to 35% at both ends near the connection terminal, but in the case of the present invention, it was 3 to 6% lower than the conventional product.
Withstands double or more spot use,
Moreover, the wire breakage rate was 10% or less even at both ends, and especially when the outermost layer and the child twists in the lower layer were twisted in the same direction, wear breakage became even less likely to occur.

[Effects of the Invention] As described above, according to the present invention, the bending resistance and operation resistance characteristics can be significantly improved compared to conventional products without impairing conductivity, and lead wires for power supply of welding robots can be used. As this type of flexible conductor used in applications such as the above, it is possible to prevent wear and disconnection over a long period of time, and to greatly increase its durability. Moreover, since the copper alloy is used only for the child twisted wires in the lower layer that are in contact with the outermost layer, the amount of relatively expensive copper alloy used can be reduced. In particular, among the lower layer child twists that are in contact with the child twists in the outermost layer, the strands of the collective stranded wire in the outer layer part where wear and breakage are most likely to occur are made of softened copper alloy wire, and the other strands of the collective stranded wires are made of pure annealed copper. When it is made into a wire, the amount of the copper alloy used is even smaller, and it can be manufactured and provided at low cost.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a cross-sectional structure showing an embodiment of a flexible conductor of the present invention, Fig. 2 is a schematic diagram of a cross-sectional structure showing another example of the present invention, and Fig. 3 is a schematic diagram of a cross-sectional structure showing a flexible conductor according to an embodiment of the present invention. FIG. 4 is a plan view showing a state in which the flexible conductor is used connected to a terminal, and is a schematic illustration of the cross-sectional structure of a conventional flexible conductor. (1)...Collected strands, (ld)...Collected strands in the outer layer (1e)...Collected strands in the center, (2)...
Composite twisted wire, (2a) (2b) (2c)... child twist of each layer, (3)... flexible conductor.

Claims (2)

[Claims] 1. In a flexible conductor in which a composite stranded wire is made by concentrically twisting a group of stranded wires, and the child strands are further concentrically twisted to form a composite stranded wire, the strands of the child strands constituting the outermost layer are made of pure annealed copper wire. A bend-resistant and vibration-resistant flexible conductor, characterized in that the wires of the lower layer of child twists in contact with the child twists of the outermost layer are softened copper alloy wires as described in (a) below. (a) A copper alloy containing Fe and Ag in a content of Fe: 0.1 to 2.5% by weight, Ag: 0.03 to 0.5% by weight, and the balance being copper. 2. In a flexible conductor in which a composite stranded wire is made by concentrically twisting a group of stranded wires, and the child strands are further concentrically twisted to form a composite stranded wire, the strands of the child strands constituting the outermost layer are made of pure annealed copper wire. , the strands of the aggregated stranded wire in the outer layer portion of the lower layer of child strands that are in contact with the child strands of the outermost layer are made of softened copper alloy wire as shown in (a) below, and the strands of the other aggregated stranded wires are made of pure annealed copper wire. A flexible conductor that is resistant to bending and vibration. (a) A copper alloy containing Fe and Ag in a content of Fe: 0.1 to 2.5% by weight, Ag: 0.03 to 0.5% by weight, and the balance being copper.