Patent – A Device for Measuring Parametrs of a Wire Rope
This patent for a device to measure the parameters of wire rope in the Inventor’s Corner column of the Wire Rope News & Sling Technology magazine.
Pat. 10,690,482 U.S. class 1/1 Int. class G01B 11/10
Inventor: Davide Rossini, Milan, IT., Giuliano Ambroset, Milan, IT.
Assignee: edaelli Tecna S.p.A., Milan, IT.
This patent presents a device for continually and automatically measuring geometrical and shaping parameters of a rope comprising a first plate and a second plate parallel to each other and constrained in a removable way by means of spacer means and anchoring means, at least two micrometers angularly unaligned one to the other and positioned between said first plate and second plate, an encoder anchored to the second plate, in contact with the rope being the device wherein said first plate and second plate comprise a shaped opening for the passage of the rope inside said shaped opening, so that the rope centrally flows through the device and the two micrometers carry out the measurements.
As shown on figures 17 and 18, the subject of the present invention is a device 100 for continuously and automatically measuring of the geometric parameters and the shape of a steel rope comprising a first plate 1 parallel to a second plate 2, said plates being mutually bound in a removable manner through spacer means 3 and anchoring means 4, within which at least two micrometers 5, 6 are placed, which are angularly misaligned one to another and with an encoder 7 which is anchored to the second plate 2 and in contact with the rope 8. The plates 1, 2 have a rectangular face on which a contoured opening 9 is provided for the passage of the rope 8 to its interior. The device 100 is positioned on the rope by means of the opening 9.
Each micrometer 5, 6 shows a measure at each pulse of the encoder 7. The number of pulses is adjustable. Depending on the speed of the rope 8 and the setting of the encoder 7, each micrometer 5, 6 can transmit values up to the maximum frequency of the device. As shown in figure 18, the micrometer 5, 6 comprises a transmitter 12 of a LED light and a receiver 11. The LED light, preferably green in color, is emitted as a uniform collimated beam by the transmitter. At the receiver 12 a sensor is present (of a known type and therefore not shown in the figures) which measures the height of the shadow created by an object placed in the middle of the LED beam and the distance of such shadow from the ends of the LED beam.
An example of a graph of the data measured on a rope at the production step is shown in figure 19. The graph shows on the abscissa axis the space in millimeter Smm and on the ordinate one the diameter measurements D and displays the measurements of the diameters of the rope collected with one of the micrometers 5, 6 as the rope 8 runs through the measuring device 100. The variation of the measure of the diameter of the rope shown in the graph is due to the geometry of the rope which is formed by strands.
Further subject of the present invention is a method for continuously and automatically measuring the geometric parameters of a steel rope by means of the device which is the subject of the present invention. Said method comprises the following steps: placement of the device 100 on the rope 8; measurement of the geometric parameters of the rope through micrometers 5, 6; analysis of the acquired data. A specially designed software collects such data and analyzes the same continuously, and processes them in order to obtain the desired values. These values are continuously updated during the passage of the rope 8 inside the device 100, so as to monitor in real time all its geometric parameters.
The diameter is read from the led sensor through a specific interface (USB or ethernet). According to an embodiment of the present invention, the detected diameters are two, one for each LED sensor connected to the controller. According to a further embodiment of the present invention, the detected diameters are three, and this is a further LED sensor connected to the controller. The data collection vectors are then respectively R1 (“Raw” data from sensor 1), R2 (“Raw” data from sensor 2) and eventually R3 (“Raw” data from sensor 3). This is detected by a third sensor, positioned at a certain distance (as a function of the cable pitch) from the first two sensors and then provides the data vector R3. The three vectors R contain not only the diameter data from the three LED sensors, but also their position (in space domain) calculated according to a vector V (because the sensors return values in the time domain).
To measure the diameter, the software simulates the action of a gauge caliper with plates, normally used for the measurement of the diameter of a rope. To this end, only the maxima of the obtained graph curves (figure 19) for both micrometers 5, 6, are considered. The following process is carried out separately on each of the three series of sensors (on the raw values R1, R2 and R3) in which the absolute minimum and the absolute maximum are detected. They are then taken into account for the first series of the maximum values (the values C1, C2, C3), carrying out the measurements for the entire length of the rope. The same is repeated for the second and the third set of values.
The instantaneous measurement of the diameter of the micrometer 1 is the maximum among a plurality of Max which can be set as desired (that is, the width of the gauge plates, set by the user). The same applies for the micrometer 2, etc. The measure of the diameter of the rope at that point is the average value of the measures of the 2 micrometers. Such measure is updated for each gauge length in real time. The software is also able to identify and “clean up” any wrong values detected on the surface of the rope, which, if taken into account, would jeopardize the correct identification of one or more maximum values, and then the measurement of the diameter of the rope (and the correlated quantities) obtaining true maximum values C1P, C2P, C3P.
Always according to the present invention, for the extraction of the diameter values, the three maximum values C1P, C2P and C3P are considered and are defined as G1, G2 and G3. Later, the average between G1, G2 and G3 is calculated, such value representing the rope diameter G at that point.
Furthermore, it is possible to simulate the width of the gauge plates, by considering any number among the maximum values, depending on the type and of the geometric characteristics of the analyzed rope. The measure of the diameter for rope with an odd number of outer strands follows the same mode, but in addition to that, the software multiplies the value obtained by the measurement by a geometric coefficient, suitably calculated in order to obtain the measure of the circumscribed circle (i.e. the diameter of the rope).
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