JPH0448511A - flat cable - Google Patents

Abstract

PURPOSE:To manufacture a flat type cable having no self-tortion by previously selecting a pitch according to a bending elasticity modulus or the like of a wire core also in the flat cables constituted from various kinds of wire cores. CONSTITUTION:In the moment of tortion T of a flat type cable 4 synthesized of all wire core units, provided that the moment sum of an S twist, a Z twist is Ts, Tz respectively, it comes to T=SIGMA[2XAiXni/{(Pi/2piri)<2>+1}]=Ts-Tz. Even when thickness of a wire core, bending elasticity, the number of wire cores, the wire core unit number of S twist and Z twist composing the flat type cable are different, self tortion of the flat type cable can be prevented by making the strand moment sum almost zero, that is, T=Ts-Tz=0 while properly selecting a pitch Pi according to a pitch circle ri drawn by a bending elasticity coefficient Ai of the wire core of each wire core unit, the wire core unit inner wire core number ni and a wire core central axis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flat cable composed of a core unit made up of several twisted wires.

[Conventional technology] An example of a conventional flat cable will be explained with reference to the drawings.

In FIG. 2, a flat cable 4 is constructed by arranging six wire core units (wire core groups) 2 in parallel in which four wire cores 1 are twisted together and integrally covering them with a sheath 3 in a flat shape. Now, wire core 1
If the direction of twisting is S-twist (right-handed twist) as shown in Figure 3 (a), the elastic force of the individual wire cores l to return to a straight line will cause the cross section in Figure 3 (b) to change. A torsional restoring force acts in the direction shown by the arrow in the figure.

Therefore, if the fiber unit 2 of the flat cable 4 shown in FIGS. 2(c) and 2(d) is constructed with all S-strands, the flat cable 4 will twist in the direction of the arrow shown in FIG. 2(d). This will result in

As a measure to prevent such twisting of flat cables, conventionally, for example, as shown in FIG. By arranging them in pairs and alternately, twisting was prevented.

Considering this method, it would not be possible to successfully manufacture a 25-fiber flat cable instead of the 24-fiber (4-fiber x 6 units) flat cable shown in Figure 2, but instead a 32-fiber (4-fiber x 8 unit) or 30-fiber cable. (5 cores x 6 units).

[Problems to be Solved by the Invention] In the prior art described above, the flat cable that twists by itself has the following drawbacks.

■If the cables are suspended in a U-shape, such as a tail cord for elevator lifts, there is a risk that the flat cables will get tangled together like twisted candy and break.

■Even for fixed wiring, the construction space and closing dimensions are large, making construction difficult.

In addition, the conventional solution of making the number of fiber units in Sl and Zll the same is that the number of cores is increased beyond the necessary number, which is extremely disadvantageous economically.

This invention was made in view of these points, and S
It is not necessarily necessary to have the same number of twisted cable units (m and z).The purpose of the present invention is to provide a flat cable that does not twist itself.

[Means for Solving the Problems] In the present invention, in a flat cable in which a plurality of units (wire core groups) each consisting of a plurality of wire cores are arranged in parallel, s
t = The force that tends to untwist the S-twist and Z-twist units ("r,, T,) by appropriately determining the twisting pitch of the reunit (Ps) and the twisting pitch of the Z-twisting unit (P2). The total sum is approximately zero (T＠ +T
It is a flat cable characterized by having a

Further, in the present invention, in the flat cable according to claim (1), in which only the number of units (N, NZ) of S twist and Z twist differs, the twisting pitch is approximately P z / P
This is a flat cable characterized in that s = -rTI""; near I).

[Example] Hereinafter, the present invention will be described in detail based on the drawings. 1st
Figure (a) is a cross-sectional view showing a part of the flat cable, and is shown for an arbitrary (first) core wire unit. That is, from the center of the flat cable 4 to the core unit 2
1. Flood the distance to the center 1. Let r be the radius of the pitch circle 11 drawn by the center axis of the cotton core 1. Now, Fig. 1 (b)
As shown in , if the torsional restoring force of any core unit 21 is f, then the torsional moment t with respect to the central axis of the flat cable 4 is tl ''= (I2t +rl)Xfl-(j!l
rllXfl=2XrIXf+ ++
It can be expressed as (1).

On the other hand, assuming that the torsion restoring force f is proportional to the force of returning the wire core 1 bent at the radius of curvature R to a straight line as shown in FIG. , (1/
Since it is proportional to R,l, the torsional restoring force f is the bending elastic modulus of the wire core as A, and the number of wire cores in the wire core unit 21 as n+
When closed, fl = A+ Xn+ X (1/ R+
) = AI X nt/(r+ x ((P+/27c
rtl”+t)].

Therefore, the twisting moment T of the flat cable 4 synthesized from all core units 2 is "Ts - T, where the sum of moments of S twist and two twists is Tm and Tz, respectively.
z...(4).

In addition, using the same number of core units, the number of S-twist and 2-twist units (N, , Nzl and pitch (pm, p, l)
If only the twisting moment l-
T is T=2XAXnX [N,/((Ps/2'πrl"
+11 is obtained.

Furthermore, when (P/2xrl")1.TmO, from the above equation (5), P, /P, = FX7fugotsu... (6) That is, from the above equation (3) or 6), When explaining the functions and effects of this invention, the following can be said.

(1) Thickness and bending elasticity of the wire cores that make up the flat cable,
Even if the number of cores and the number of S-twist and Z-twist core units are different, the bending elastic modulus A+ of the core of each core unit, the number of cores in the core unit n,
The six axes in the center of l and u are drawn (according to the pitch circle rl, the pitch P is appropriately selected and the total torsion moment is set to approximately zero, that is, T = "r* - T2 = O," Self-twisting can be prevented.

(2) Number of core units using the same core: IN-, NZ)
For flat cables that differ only in pitch (Ps) that satisfies T=O in equation (5) above.

P2), and if the pitch/pitch diagram ratio is sufficiently large, the pitch can be easily selected using the above equation (6).

In the above embodiment, l is a wire core and 2 is a twisted wire core unit (M6 group). The action and effect of cables are exactly the same.

[Effects of the Invention] As explained above, the flat cable of the present invention is capable of self-twisting by selecting the pitch in advance according to the bending elastic modulus of the wire cores, even in flat cables composed of many types of wire cores. It is possible to manufacture a flat cable without any cracks, and it is possible to manufacture without prototyping.

■The number of core units may be an even number or an odd number, so there is no need to increase the number of cores unnecessarily.

(2) Due to the features shown in (2) above, a flat cable without self-twisting can be provided extremely economically.

[Brief explanation of drawings]

FIG. 1(a) is a cross-sectional view showing a part of a flat cable according to an embodiment of the present invention, FIG. 1(b) is a line section showing the position and direction of the point of force, and FIG. 1(c) is a line Figure 2 is a cross-sectional view showing an example of a conventional flat cable; Figures 3 (a) and 1 (b) are diagrams for explaining the self-twisting of flat cables. Side view, cross-sectional view, third side view of the core unit
Figures (C) and (D) are a cross-sectional view and a perspective view of the flat cable. Figure 1... Core 2... Core unit (I6 group) 3... Sheath 4... Flat cable 11... Twisted pitch circle 12... Center line of the core

Claims (2)

[Claims] (1) In a flat cable in which multiple units (wire core groups) each consisting of multiple wire cores are arranged in parallel, the twisting pitch (P_s) of the S-twist (right-twist) unit and the Z-twist (left-twist) unit By appropriately determining the twisting pitch (P_z), the sum of the forces (T_s, T_z) that tend to untwist the S-twist and Z-twist units can be reduced to approximately zero (T_z).
s+T_z=0). (2) Number of S-twist and Z-twist units (N_s, N_
2. The flat cable according to claim 1, wherein the flat cable differs only in z), characterized in that the twisting pitch is approximately P_z/P_s=√(N_z/N_s).