JPS5825011A - Spiral enclosed cable - 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 The present invention relates to cables provided with helical elements, such as coaxial cables, multiple pair cables, and optical waveguide cables used for communications.

Communication cables, such as coaxial cables, multi-pair cables, or optical waveguide cables that include one or more threaded elements, are used in a variety of fields. If the spiral wrap is placed near the exterior of the cable, the wrap can serve as a covering component for the cable. Other spiral wrap elements include tape, plastic ribbons, binders, and the like. Spiral wraps made of conductive materials can also be used to transmit power or information.

If no steps are taken to avoid this, a torque response will typically occur in the helical element and against the cable. In other words, when an axial force is applied to the cable, the cable tends to elongate and twist. This twist can either tighten or loosen the helical wrap, depending on the composition of the cable. Such a torque response may cause knots to form in the cable when pulling it out of the drum or otherwise, for example when laying the cable. Other handling problems may arise due to torque response. Tightening or loosening the threaded elements also adversely affects cable performance.

It is possible to neutralize the torque response of one or more spiral layers by imparting an opposite torque response to the other spiral layers. For example, a spiral layer wound in the opposite direction can neutralize the torque of a spiral layer wound in the opposite direction.

Techniques have been developed to analyze the torque response of a helically wound cable, and the correct angle for total neutralization of the helical element can be predicted. Such techniques are described, for example, by T.C. Cannon and M.R. Santana at Cherry Hill, New Chassis.
This was announced at the 24th International Wire and Cable Symposium held in 1975 and published in the newsletter.
"Mechanical Characteristics of Cables Containing Helically Wound Reinforcing Elements"
rizatofon of CablesContain
ing Helically Wrapped Rei
nforcingElements” by To
C, Cannon and MeR.

5antana in the Droceeding
s of the 24th International
al Wire and Cable Symposf
um (1975), Cherry H3ll, Ne
See the paper entitled W Jersey).

The present invention provides a cable consisting of a spiral element surrounding a cylindrical core, and the angle θ of the spiral element is such that when stress is applied to the cable in the axial direction, The helical element is selected to provide essentially zero torque response.

In one embodiment according to the invention, said angle θ is selected according to the following equation: That is, θ=tm −' [N −”2] ΔRe/Re where N=7°./Lc, where Re is the radius of the core, Lc is the length of the segment of the core, and ΔLc
is the change in length of the segment caused by applying an axial stress to the core, and ΔRe is the corresponding change in the radius of the core.

The already described features of the invention, as well as other features, will now be explained with reference to the drawings.

A spiral wrap cable with a single spiral wrap that provides zero torque response will be described in detail below. A single helical wrap in the present cable design produces zero torque on the threaded cable core. Thus,
Prior to winding the threaded element onto the cable core, cables made with threaded elements can also be subject to the presence of applied axial strain, provided that the cable core has essentially zero torque response characteristics. essentially zero torque response is obtained.

As shown in the above article by Cannon and Santana, the strain in the helical element (ε8) is related to the axial strain in the cable and is given by equation (1). That is, ε8=εc(Coo”θ−Nstr+20)−φ(xR
BtAn 2θ) (1) Here, ε. is the axial strain in the cable, and θ is the angle of the helical element (the angle between the longitudinal axis of the cable core and the axis of the helical element).
, φ is the cable torsion in turns per unit length due to the axial strain, R8 is the radial position of the helical element, and N is the axial strain i) # in the helical element. is the radial strain for a unit axial strain observed in the cable core.

N is given by equation (2).

Here, Rc is the radius of the core around which the spiral element is wound,
Lc is the length of the core segment.

The zero torque response is determined by solving Equation (1) as follows. First, if the twist is zero at the end (φ = 0), the strain in the helical element ε8 under the condition of zero torque is
becomes zero. This occurs when the angle θ is selected according to the following equation.

θ= tan-” (N-”2] (4
) Therefore, by evaluating the values of ΔRc/Rc and ΔLc/Lc, the value of the angle that produces zero torque can be determined.

A suitable test setup for determining these values is shown in FIG. Stress source is 174 inch steel twisted rope 12
It can be a six gear drive winch 11 connected to the cable core via. The hook 13 is attached to the rope by a swivel connection, and is attached to the cable core 16 to be tested by the handle 14. The cable core to be tested is attached to and transmitted to the load measuring device 1B via the handle 17. A suitable load measuring device 18 includes a Tyco JP-2000 load cell manufactured by Data Instruments (DataInstruments).
trnments Inc., Tyeo Model
JP-2000), and this measuring device is attached to a fixed object 19. Starting from a zero (or predetermined) stress state, the change in length of the cable core under test is
It is determined over the entire range of the given gauge length depending on the applied stress. Gauge length is measured such that the cable core includes sag and gives the length of the cable core as if it were suspended. The gauge length is what gives the value of Le. The diameter of the cable core under test is also measured using, for example, an Instron Model G-57-11 longitudinal force sensor.

The diameter is first determined under the same stress conditions as the gauge length measurement, but again with the same stress applied to measure ΔLc. The RcO value is 1/2 of the initial diameter value, and ΔRc is 172% of the change in the original diameter under the above applied stress.
It is.

To improve accuracy and consistency in determining N, it is desirable to measure the above data with increasing stress and average the resulting N values. A more desirable method in many cases is to use a least squares method, which fits the data by entering successive stress increments into a regression equation. If zero strain can be assumed as a result of applying a small stress in advance, Equation (5) can be used.

Here, ε1 is the radial strain of the core, εL is the axial strain of the core, and K is a constant.

ε1=-NεL-1-K (5) In this equation, the data point ΔRC/RC1ΔL c/L c
Each set of is plotted or recorded on a graph using ε1 and εL as coordinate axes.

The values of N and K are selected such that the line segment with the smallest deviation (most/J% squared deviation) is obtained from the data. Through numerical calculation, N and K are determined alternately from the data points by a known method.

This technology has been fully applied to optical waveguide cables. In optical waveguides, it is important to have a low tendency to introduce i66 into the cable during handling.

This is easy when a zero torque response is obtained at the layer under test on the cable. As an example to explain this technology,
Optical waveguide cables consisting of optical fibers are to be measured to determine the appropriate 1h angle of the helical coating layer, except as described in U.S. Pat. No. 4,241,979. .

Practical Example Basically, as shown in FIG. 2, an optical waveguide cable is assembled as described below. The cable core is inside the spiral jacket layer 209,210 and is present in all parts of the cable. An optical waveguide space exists at the center of the core, and it can be mounted in a ribbon shape. Typically, each ribbon 201 is comprised of twelve optical fibers, although a slightly smaller number is shown for clarity. In the illustrated cable, the ribbon is twisted at a rate of one twist per 46 crn. Unsintered polytetrafluoroethylene (PTFE) tape (not shown) was applied to the entire ribbon to act as a thermal barrier. The PTFE tape has a width of 21 mm, has a float of 0.08 mm, and is overlapped and sewn in the longitudinal direction. A polyethylene tube 202 protruding outside the PTFE tape acts as a protective chamber for the ribbon structure. The tubing is high density polyethylene formed as a continuous extrusion with an internal diameter of 6.35 m and a thickness of 0.71 tm. A twisted and glued polyester tube 203 is installed over the entire polyethylene tube.

The tape has a width of 2.54 ctn and a thickness of 0.2 cm, and is overlapped and sewn in the longitudinal direction. The next layer is 1
It consists of four stainless steel wires 204, each wire 0.43 mm in diameter and made of 302 mm stainless steel. The wire is configured to make one turn per 25.4 crn longitudinal distance. The next layer is a polyethylene 205 jacket constructed over the steel wire. The wall thickness of the jacket is 0.69+o
+, It is a continuous protrusion made of high-density polyethylene with an outer diameter of 75E9.78.

Twisted and glued polyester tape 206 is 2.5
This tape, which is 4 crn wide and 0.2 M thick, will be installed next. Attach the tape in the longitudinal direction and
: 201 forms the next layer with a gap of 5.6 tan, and is twisted and wound in the opposite direction to the preceding wire, forming one turn at 38.4 ω. There is.

The wire is ÷302 stainless steel and has a diameter of 0.43 mm. A jacket of polyethylene 208 forms the next layer, and steel wire is incorporated into the polyethylene wall thickness. This jacket has a thickness of 1.02
m5 and has an outer diameter of 12.2 m. This cable core has essentially zero torque response.

To determine the value of N for this cable core, tests were conducted in the experimental setup shown in FIG. is X:2
A length of cable core sufficient to provide a gauge length of 97 cm (11 fins) was suspended from rollers 15 as shown. Cable diameter was measured at the midpoint using an Instron longitudinal strain sensor.

Next, use a winch to apply stress to the cable to lengthen it to a ΔLc of 0.79■ (1/32 inch).
I got it. The longitudinal strain sensor was again used to measure the diameter 2Rc to determine the value of ΔRc. The axial stress applied to the winch was increased to 0.79 mm (1/32
inch) was further extended and the measurement was repeated. The measurement process was carried out for 24 incremental stress values, totaling 1.
An elongation of 91 cm (3/4 inch) was obtained. Next, the values of ΔLc/Lc and ΔRc/Rc were determined for each increment. When all sets of data points have been found,
These were entered into equation (5), and the values of N and K were determined by the least squares fitting method. Next, three sets of elongation values were separately prepared starting from zero stress, and the average value of N was thereby determined to be 0.42.

From this, the first angle θ was calculated from equation (4), and was determined to be 57°. For the upper cable core, 1 foot (0.30 meters) for the spiral jacket layer on the core.
I got 12 turns per turn. Appropriate coating layer is 57°
Consisting of two angled steel wraps, each wrap has the following characteristics: That is,
The width is 16.3 m, and the thickness is 0.127 m + 5.59 m on each side.

These wraps can be applied to the overlapping portions 209, 210 as shown in FIG. 2 to ensure that no gaps occur when bending the cable. However, they have the same 1B angle, the same direction of twist (i.e., they both have a right-hand 1H, or left-hand twist), and they have essentially the same distance from the center of the core. Therefore, for purposes of this invention, they are considered to be a single helical element. Rather than forming alternating overlapping ends, as shown in FIG. 2, each end of the wrap can be configured to cover the other.

Further wraps could be added in a similar manner, but would still be considered a single threaded element. Finally, a jacket of high density polyethylene 211 can be protruded over the entire helical covering layer.

The resulting cable has essentially zero torque response.

A simple approximation method for determining the cable torque response is:
This is to measure torsion in such a way that no strain occurs in the cable when stress is applied. It is possible to suspend the cable vertically and stress it by weight.

For the purposes of this invention, a vertically suspended length of 100 meters (328 feet) when subjected to an axial strain of 1 inch will result in less than 3 turns of cable twist, and in some cases The cable is considered to have zero torque response. This principle can be translated to other lengths and other twists, and when an axial strain of 1 inch is applied, a twist smaller than 0.3 turns will occur for a length of 1.0 meters. Become. A similar measurement method that provides essentially the same information is to measure the torque of the cable when stressed under conditions of torsional strain and divide it by the cable torsional stiffness. For example, using the experimental setup of FIG. 1, a torque meter can be installed in place of the load cell. Vibrac
A suitable torque transducer manufactured by T.P. Corporation is the TQ1600 static transducer. For a given 6%ib, the Tor6 value in Newton meters is determined. Next, the torsional stiffness of cables of the same length is determined according to known techniques.

The torque strain rate divided by the torsional stiffness gives a figure of merit with the dimensions of turns per meter per unit strain. By this measurement process, cables having a figure of merit of less than 3 turns per meter per C-strain are considered to have essentially zero torque response for purposes of the present invention. In this case, a figure of merit of less than one turn per meter per unit strain can be achieved by the present invention with commercial feasibility.

In modern cable manufacturing operations, ±
It is typically possible to obtain the angle of the screw within 1°. In the cable in the above example, the deviation from the design value of 12 turns per foot (0.30 meters) is ±1 per foot (0.30 meters).
/2 turns.

It will be appreciated that once it has been determined that an essentially torque-free mono-spiral layer can be installed, other techniques can be used to find the appropriate twist angle. The most straightforward technique is to simply vary the angle of the sheath by varying the number of turns per foot of the helical element relative to the core by more or less, and thereby test the torque response of the cable. In this method,
A spiral layer with essentially zero torque response is obtained. Typically, cores that can be fitted with zero-torque spiral layers will also have essentially zero-torque response. The resulting cable thus has essentially zero torque response. However, it is possible to install a zero torque responsive spiral layer in accordance with the techniques of the present invention to a core that essentially does not have a zero torque response. If the twist were to re-strain, the resulting cable would have essentially the same torque response as the core before the threaded element was attached. , No. (
4) The value of N in formula can also be determined by other techniques than the described testing method. For example, assuming the core is an essentially homogeneous incompressible material, the value of N can be theoretically calculated to be 0.5. Using non-uniform core materials, the experimental method described above is convenient for evaluating N, especially when N deviates from the theoretical value by more than 10 cm, i.e. when N is 0. It is advantageous if it is smaller than 45 or larger than 0.55.

Spiral layers other than the covering layer can also be applied advantageously. For example, the tape layer, the thread can be equipped with a twisted wire layer. While various modifications of the present invention may be considered as improvements over known techniques, such modifications do not go beyond the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 shows a suitable set of experiments for determining the parameters used to calculate the angle of helical twist. FIG. 2 is a diagram illustrating a fiber optic cable provided with a spiral coating layer according to the present invention. [Explanation of symbols of main parts] 201... Ribbon-shaped core 203... Polyester pipe 202. 205. 208... Polyethylene pipe 204.
204... Steel wire 206... Polyester tape 209.210... Spiral coating 211... Outer coating

Claims (1)

Claims: (1) A cable consisting of a threaded element surrounding a cylindrical core, wherein the threaded element has an essentially zero torque response when stressed in the axial direction. A cable characterized in that the angle θ of xB of the shaped element is selected. (2. In the cable according to claim (1), the angle θ is expressed by the following formula: % formula % RC: radius of the core, Lc: length of the segment of the core, ΔLc: axial stress on the core , a change in the length of the segment caused by , ΔRc: a change corresponding to the above in the radius of the core. (3) Claim (2) suspending a segment of the core; measuring the length of the segment or a portion of the segment; measuring the diameter of the core; and suspending the segment to determine the strain in the segment. by applying a stress to the Lc, ΔLc, Re, ΔRe and measuring the result of the change in length; and measuring the result of the change in diameter. (4) A cable according to claim (3), characterized in that the core is essentially incompressible, whereby N
A cable characterized in that the value of is different by more than 0.5 and is smaller than 0.45 or larger than 0.55. (5) In the cable according to claim (3), the measurement is performed various times for various strains generated by various stress increments, and then a least squares fitting method is applied to the obtained values. A cable characterized in that an operation is performed to obtain the value of N from the following equation by applying the following equation. ε, = -NεL+niko\, εL: Strain in the axial direction of the core, K: Constant (6) Claims (1) or (2) or (3) or (4) ) or (5), wherein the cable produces an essentially zero torque response when stress is applied axially to the cable consisting of the helical element and the core. , wherein said cylindrical core produces an essentially zero torque response to axial stresses. (7) The cable according to claim (1) or (2) or (3) or (4) or (5) or (6), wherein the cylinder A cable characterized in that its shaped core is made up of one or more optical waveguides. (8) Claims paragraph (1) or (2) or (3) or (4) or (5), or (
The cable according to item 6) or item (7), wherein the threaded element is a metal coated element.