JPH0441699Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a call line used for introducing and wiring electric wires, cables, etc. into piping. [Conventional technology and its problems] Conventionally, for example, a steel wire with a flat cross section was generally used as a call wire used to guide and introduce electric wires, cables, etc. into piping. Because it is flat, it is easy to bend in one direction, but difficult to bend in a direction perpendicular to this easy bending direction, causing problems such as difficulty in passing the pipe through. In addition, those using synthetic resin wire with a circular cross section,
Although there are no problems such as difficulty in bending depending on the bending direction, since it is made of synthetic resin, its tensile strength is low and it is inferior in terms of rigidity, which is most required for a nominal line. It is not possible to ensure a large amount of In other words, a problem arises in that the linearity is not maintained properly during insertion. Furthermore, because of the circular cross section, the area of contact with the inner circumferential surface of the pipe becomes large and the frictional force also increases, resulting in poor workability. Furthermore, there are also wires made of twisted wires made of synthetic resin wires, but since a plurality of wires are twisted together, there are manufacturing difficulties and high costs. Depending on the twist pitch, wire diameter, etc.
When pushed into the pipe, multiple strands of wire bulge and come apart, resulting in the pushing force being absorbed and reduced by the bulge, which causes problems such as a significant drop in wire threading efficiency. Ta. Also,
Since it has a structure of multiple stranded wires, it has problems such as low rigidity and easy bending, making it unsuitable for long pipes. The object of the present invention is to provide a call line that solves the above problems. [Means for Solving the Problems] The present invention consists of a single wire obtained by further stretching in the longitudinal direction a synthetic resin wire formed into a substantially triangular cross section. [Function] Since it is formed into a substantially triangular cross section, the contact with the inner surface of the pipe is a line contact, and the frictional resistance is small, and the resistance during insertion is reduced, so the distance that can be inserted is increased. Furthermore, due to its cross-sectional shape, there is no direction in which it is difficult to bend. Furthermore, by continuous molding of synthetic resin, a synthetic resin wire rod with a substantially triangular cross section can be easily manufactured, and it is also extremely easy to further stretch this wire rod. By doing so, the tensile strength and the like can be increased and the rigidity can be increased. [Example] An example of the present invention will be explained in detail based on the drawings. In FIGS. 1 to 4, reference numeral 1 is a call wire according to the present invention, and a tip metal fitting 2 is fixed to the tip portion 3 of the call wire. Reference numeral 9 denotes a tip fitting hole portion into which the tip portion 3 is inserted. The tip fitting 2 is fixed by caulking, fusing, gluing, or the like. 8 is the tip metal fitting 2
This is a hole for hanging electric wires. Therefore, as shown in FIG. 4, the call line 1 is
It is constructed by further stretching in the longitudinal direction a synthetic resin wire M, which has longitudinal recesses 5 on three sides 10 and is formed into a substantially triangular cross section. In order to perform the above-mentioned drawing process on the wire rod M, the wire rod M is continuously formed by extrusion molding or the like.
It is sufficient to continue applying a tensile force to the film, and this takes advantage of the property that stretching significantly advances crystal orientation and increases strength. Note that after the synthetic resin wire M formed into a substantially triangular cross section is cooled, the tensile force may be applied cold, or the tensile force may be applied after the synthetic resin wire M is reheated to a predetermined temperature. You can do it like this. The cross-sectional shape of the drawn wire 1 is approximately triangular as shown in FIG. 3, and its three corners 4 are rounded.
Recesses 5 are provided in the longitudinal direction between the corners 4. Materials for synthetic resin wire M include nylon 6, nylon 66, and nylon.
It is possible to use polyamides such as 610, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyolefins such as polypropylene, or polyacetals. Table 1 shows the results of measuring the tensile strength of the call wire 1 constructed in this way. Figure 5 schematically shows the measurement method, in which the reference wire 1, which is the sample to be measured, is supported between supporting points 6 and 6 separated by a predetermined distance (L = 100 mm), and a static load of 2 kg is applied to the center position. This was done for the case where W was added. Regarding the bending strength in the table, the amount of deflection δ at the center position was measured and used as a guideline. Regarding the measured cross-sectional shape of the nominal wire 1, its representative dimensions a, b, and c are shown. The synthetic resin material used was polyethylene terephthalate.

[Effect of idea]

The present invention has the following remarkable practical effects with the above-described configuration. Unlike conventional steel wires with a flat cross section, the wires are not difficult to bend in a certain direction due to their cross-sectional shape, and a nominal wire can be easily routed in accordance with the bent state of the piping. Stretching the synthetic resin increases its tensile strength and improves its elastic modulus, so it is possible to ensure a large insertion length when pushing the nominal line into the pipe. That is, compared to conventional synthetic resin wires having a circular cross section, the wires have greater rigidity (spring characteristics), so they are better able to maintain a straight line when pushed in, improving workability. Also, line breakage is prevented. Compared to a structure made of twisted wires made of synthetic resin wires, it is easier to manufacture and costs are reduced. Unlike this conventional stranded wire structure, no unraveling or blistering occurs, so the pushing force is effectively transmitted to the tip fitting 2, resulting in good workability. Furthermore, unlike a stranded wire structure, since it is made of a single wire, the wire does not deteriorate in rigidity and is not easily deflected, so it can be easily passed through a pipe that is quite long and has many curved parts. Compared to conventional pipes with a circular cross section, the frictional resistance against the inner surface of the pipe is smaller, making it easier to push and pull, resulting in better wire running efficiency.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a partial cross-sectional side view of the tip part, Figure 3 is an enlarged cross-sectional view, Figure 4 is a perspective view of the synthetic resin wire, Figure 5 is a schematic illustration of the measuring device, Figures 6 and 7 are FIG. 7 is a cross-sectional view showing other embodiments. M...Synthetic resin wire.

Claims (1)

[Scope of utility model registration request] Synthetic resin wire rod M formed into a substantially triangular cross section
A calling wire characterized by being made of a single wire further stretched in the longitudinal direction.