JPH0890691A - Multi-layered cylindrical body - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the durability of a cylindrical body having a wire rod spirally wound on the inner and outer layers. A multi-layered cylindrical body having an inner layer and an outer layer formed by spirally winding wires 11 and 14, respectively,
The ratio (Pi / Di) of the spiral pitch Pi to the winding diameter Di of the wire rod 11 in the inner layer is set to be larger than the ratio (Po / Do) of the pitch Po to the spiral winding diameter Do of the wire rod 14 in the outer layer. Since the bulge of the inner layer due to bending is smaller than that of the outer layer, the compressive stress between the inner and outer layers can be suppressed and the durability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective cylindrical member, and more particularly to a cylindrical body formed by spirally winding a wire rod to impart flexibility.

[0002]

2. Description of the Related Art In the case where flexibility is required in addition to a predetermined crushing strength as an exterior body, a cylindrical body in which an appropriate wire is spirally wound in multiple layers is conventionally known. An example thereof is shown in FIGS. 3 and 4, and the multilayer structure cylinder body 1 shown here has a wire rod 3 such as a metal wire or a highly rigid synthetic resin wire spirally wound around an outer peripheral surface of a suitable base cylinder 2. The outer layer-side wire 5 is spirally wound around the outer periphery of the outer layer via the intermediate layer 4, and the outer coating 6 is formed on the outermost periphery.

Therefore, in this type of cylindrical body 1, since the wire rods 3 and 5 at the inner and outer circumferences have a predetermined rigidity, it is possible to secure a crushing strength and the wire rods 3 and 5 are spiral. Since it is wound into a shape, the cylindrical body 1 as a whole exhibits flexibility.

[0004]

The reason why the cylindrical body 1 exhibits flexibility is that the wire rods 3, 5 are both twisted and deformed and the winding pitch is changed. Specifically, the winding pitch of the wire rods 3 and 5 becomes smaller on the inner circumference side of the bending,
On the other hand, on the outer peripheral side, the winding pitch of the wire rods 3, 5 increases, and the wire rods 3, 5 are twisted due to such deformation.

However, conventionally, even if the winding directions of the wire rods 3 and 5 may be different, the inner and outer layers are
The ratio of the winding pitch to the winding diameter is made the same, or the winding pitch of the inner layer wire 3 is made smaller due to the smaller winding radius of the inner layer. Therefore, the stress generated between the inner layer and the outer layer due to bending is reduced. growing. That is, in the above-mentioned conventional cylindrical body, a compressive stress is generated between the inner layer and the outer layer due to a substantial increase in the winding diameter due to a change in the pitch of the wire rods of the inner and outer layers due to bending, and as a result, wear of the wire rods 3 and 5 and There is a disadvantage that the durability of the cylindrical body 1 as a whole is lowered due to damage of inclusions between the two.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a multilayer structure cylindrical body capable of reducing stress between inner and outer layers and improving durability. Is.

[0007]

In order to achieve the above-mentioned object, the present invention provides a multilayer structure cylindrical body having an inner layer and an outer layer, each of which is formed by spirally winding a wire rod. The ratio of the spiral pitch to the winding diameter is set to be larger than the ratio of the spiral pitch to the winding diameter of the wire rod in the outer layer.

Further, according to the present invention, a material to be protected can be interposed between the inner layer and the outer layer.

[0009]

When the cylindrical body of the present invention is bent, the wire rods of the inner and outer layers are twisted and the winding pitch is changed, and accordingly, the winding diameter is increased in the vicinity of the bent portion. However, in the present invention, since the spiral of the wire rod in the inner layer has a larger pitch-to-wrap diameter ratio than that in the outer layer, an increase in the winding diameter due to bending is suppressed, and as a result, between the inner and outer layers, The stress becomes small.

[0010]

EXAMPLES The present invention will now be described based on examples. In FIG. 1, a wire rod 11 on the inner layer side is spirally wound around an outer peripheral surface of a predetermined base cylinder 10 made of a synthetic material. The wire 11 is made of a steel wire, an aluminum wire, a synthetic resin wire having a relatively high rigidity, or the like.

On the outer peripheral side of the wire 11 on the inner layer side,
Protective material 12,1 which is a sheet material made of rubber or fiber
A protected material 13 sandwiched by 2 is arranged. The protected material 13 is, for example, a filament that is weaker or softer than the wire 11. Furthermore, this protective material 12,1
On the outer peripheral side of the protected material 13 sandwiched between the two, the outer layer side wire 1
4 is spirally wound. Similar to the inner-layer-side wire 11, the wire 14 is made of steel wire, aluminum wire, or a synthetic resin wire having a relatively high degree of synthesis, and a plurality of the wires are wound in close contact with each other. The outer layer coating 15 is provided on the outermost circumference.

The winding directions of the wire rods 11 and 14 of the inner and outer layers may be the same or opposite to each other, but the spiral state is different as follows. That is, as shown in FIG. 2, the wire rod 14 of the outer layer is tightly wound around the wire rod 11 of the inner layer, and specifically, the ratio of the spiral pitch Pi to the winding diameter Di of the wire rod 11 of the inner layer (Pi / Di) is the ratio (Po / D) of the spiral pitch Po to the winding diameter Do of the outer wire 14
o) is set larger than.

When the above cylindrical body is bent, each of the wire material 11 forming the inner layer and the wire material 14 forming the outer layer tries to expand due to the looseness of the spiral, but forms the inner layer. Since the wire rod 11 is so-called sparsely wound as described above, the bulge due to bending is smaller than that in the outer layer. As a result, the compressive force generated between the inner and outer layers is reduced, and the crush of the protected material 13 is prevented.

In the present invention, the inner layer and the outer layer may be continuously formed with an inclusion such as a sheet material interposed therebetween without providing the protected material 13. In the case of such a configuration, due to the small compressive force generated between the inner layer and the outer layer, it is possible to prevent crushing or wear of the sheet material between them or wear of the inner and outer layers in advance,
As a result, the durability of the cylinder itself can be improved.

Further, the present invention is not limited to the above embodiment, and three or more layers formed by spirally winding the wire may be provided. The ratio of the diameter to the pitch of the spiral can be, for example, "13" in the inner layer and "7" in the outer layer, but this value can be appropriately set as necessary.

[0016]

As described above, according to the present invention,
Since the ratio of the pitch to the winding diameter of the wire wound in a spiral shape is increased in the inner layer with respect to the outer layer, the increase in diameter due to bending, that is, the bulge is reduced in the inner layer
Therefore, it is possible to suppress the compressive stress between the inner and outer layers, prevent the crushing and wear of the two, and thus improve the durability. If a sun protection material is placed between the inner and outer layers,
Crushing and abrasion of the protected material can be prevented in advance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a winding pitch of a wire rod.

FIG. 3 is a cross-sectional view showing an example of a conventional cylindrical body.

FIG. 4 is an explanatory diagram for explaining a winding pitch of a wire rod in a conventional cylindrical body.

[Explanation of symbols]

11, 14 ... Wire rod, 13 ... Protected material, Pi, Po ...
Winding pitch, Di, Do ... Winding diameter.

Claims (2)

[Claims] 1. A multi-layered cylindrical body having an inner layer and an outer layer, each of which is formed by spirally winding a wire rod, wherein the ratio of the pitch of the spiral to the winding diameter of the wire rod in the inner layer is relative to the winding diameter of the wire rod in the outer layer. A multilayer structure cylindrical body characterized by being set to be larger than the ratio of the pitch of the spiral. 2. The multilayer structure cylindrical body according to claim 1, wherein a material to be protected is interposed between the inner layer and the outer layer.