Method and apparatus for measuring a pitch of stranded cable
View Patent ↗Disclosed is a method for measuring a pitch of a stranded cable which includes the steps of (A) manufacturing a stranded cable by stranding at least two wires; (B) irradiating a parallel ray on one side of the stranded cable moving at a regular velocity, and receiving the parallel ray at the opposed side of the stranded cable; and (C) determining a stranded cycle of the cable on the basis of a light-receiving quantity pattern on the opposed side corresponding to a stranded pattern of the cable, and then measuring a stranded pitch of the cable by calculating a moved distance of the cable during the stranded cycle. This method enables to measure a pitch of a spirally stranded cable in real time at a low cost.
1. A method for measuring a pitch of a stranded cable, comprising the steps of:
(a) manufacturing a stranded cable by stranding at least two wires;
(b) irradiating a parallel ray on one side of the stranded cable moving at a regular velocity, and receiving the parallel ray at the opposed side of the stranded cable; and
(c) determining a stranded cycle of the cable on the basis of a light-receiving quantity pattern on the opposed side corresponding to a stranded pattern of the cable, and then measuring a stranded pitch of the cable by calculating a moved distance of the cable during the stranded cycle.
2. The method for measuring a pitch of a stranded cable according to claim 1 , wherein a width of the parallel ray irradiated on one side of the cable is set at least wider than a diameter of the cable.
3. The method for measuring a pitch of a stranded cable according to claim 1 , wherein the step (c) includes the steps of:
(a) generating a light-receiving signal in a shape of non-sinusoidal periodic wave corresponding to a light-receiving quantity on the opposed side;
(b) converting the light-receiving signal into a square wave signal;
(c) dividing the square wave signal into two parts; and
(d) measuring a moved distance of the cable by using the divided square wave signal as a trigger signal.
4. The method for measuring a pitch of a stranded cable according to claim 3 , wherein the light-receiving signal has a shape of full-wave rectified wave.
5. The method for measuring a pitch of a stranded cable according to claim 3 , wherein the step (d) includes the steps of:
preparing a guide roller rotating in accordance with movement of the cable and an encoder for counting the rotation of the guide roller;
counting the number of pulses output from the encoder by using the divided square wave signal as a trigger signal; and
calculating a pitch P using the following equation,
P
=
π
D
n
×
N
where P: a stranded pitch, π: the ratio of the circumference of a circle to its diameter, D: a diameter of the guide roller, n: the number of pulses of the encoder per one rotation, and N: the number of pulses of the encoder.
6. An apparatus for measuring a pitch of a stranded cable, comprising:
a stranded cable in which at least two wires are stranded in a predetermined pitch;
a light-emitting element and a light-receiving element positioned on both opposite sides of the stranded cable moving in a predetermined direction;
a measurement sensor for sensing a moved distance of the cable; and
a pitch calculator for calculating a pitch of the stranded cable on the basis of an output value of the measurement sensor by using periodical change of the output signal from the light-receiving element as a trigger signal.
7. The apparatus for measuring a pitch of a stranded cable according to claim 6 , wherein the measurement sensor includes:
a guide roller contacted with the cable, the guide roller rotating as much as a moved distance of the cable; and
an encoder for counting the rotation of the guide roller.
8. The apparatus for measuring a pitch of a stranded cable according to claim 6 , wherein the pitch calculator includes:
a comparator for converting a light quantity signal output from the light-receiving element into a square wave;
a frequency divider for dividing the square wave output from the comparator into two parts; and
a signal processor for calculating a pitch of the stranded cable by counting the number of pulses of the encoder until the divided square wave is triggered.
9. The apparatus for measuring a pitch of a stranded cable according to claim 8 , wherein the signal processor calculates a pitch of the stranded cable on the basis of the following equation,
P
=
π
D
n
×
N
where P: a stranded pitch, π: the ratio of the circumference of a circle to its diameter, D: a diameter of the guide roller, n: the number of pulses of the encoder per one rotation, and N: the number of pulses of the encoder.
10. The apparatus for measuring a pitch of a stranded cable according to claim 6 , wherein the light-emitting element is an LED.
11. The apparatus for measuring a pitch of a stranded cable according to claim 6 , wherein the light-receiving element is a photodiode.
12. The apparatus for measuring a pitch of a stranded cable according to claim 8 , further comprising:
a first amplifier for amplifying the light-receiving signal between the light-receiving element and the comparator.
13. The apparatus for measuring a pitch of a stranded cable according to claim 12 , further comprising:
a condensor for extracting AC component from a signal of an output of the first amplifier.
14. The apparatus for measuring a pitch of a stranded cable according to claim 13 , further comprising:
a second amplifier for amplifying a signal of an output of the condenser.