JPH03262958A - Damage evaluating method for steel rope - Google Patents

Abstract

PURPOSE:To measure and evaluate the damage of the steel rope quantitatively by comparing sectional area found from magnetic flux density at each point of the steel rope with the sectional area of the steel rope when it is new and evaluating the damage according to the decrease in the sectional area. CONSTITUTION:A damage measuring instrument 2 for the steel rope 1 is provided with a magnetizer 3 which magnetizes the steel rope 1 to produce magnetic flux and a flux meter 8 which measures the magnetic flux density. The measuring instrument 2 is moved along the steel rope 1, the magnetizer 3 magnetizes the steel rope 1, and the flux meter 8 measures the density of the magnetic flux produced by the magnetization. Then the sectional area at one measurement point of the steel rope 1 is found according to the figure of the relation between the magnetic flux density and the sectional area of the steel rope of the same material under constant conditions and this sectional area is compared with the sectional area when the steel rope 1 is new (not damaged). Further, the measuring instrument 2 is moved to measure and evaluate the damage of the steel rope 1 at each point quantitatively.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention quantitatively measures damage caused to steel cables such as wire lobes and PWS (parallel wire strands) used in suspension bridges and cable-stayed bridges by magnetic means. This invention relates to a method for evaluating damage to steel cables by measuring and evaluating them.

[Prior Art] A method for measuring damage such as corrosion, abrasion, and wire breakage occurring in steel cables by magnetic means is disclosed in Japanese Patent Application Laid-open No. 55-129747.
The technique disclosed in the publication No. 1 is known. In this method, a steel cable is magnetized in its longitudinal direction, a magnetic flux detector is movably provided around the outer circumference of the steel cable, and the magnetic flux detector is moved to detect the magnetic flux density. The magnetic flux density reference curve obtained by measuring the location is compared, and through this comparison, an abnormality in the magnetic flux distribution is detected and damage to the steel cable is measured.

[Problems to be Solved by the Invention] However, in such a measurement method, it is only possible to relatively know the degree of damage at each part in the longitudinal direction of the steel cable, and it is not possible to know the quantitative damage at each part measured. It is not possible to evaluate the amount of damage, that is, the percentage of damage that has progressed to the measurement part from its new state.

For steel cables used in suspension bridges, cable-stayed bridges, etc., it is necessary to determine when to replace them by determining whether the absolute amount of damage to each part has reached a predetermined tolerance. However, it is insufficient to be able to measure the damage in each part of the steel cable as a relative comparative amount as in the conventional method.

This invention has been made with attention to these points, and its purpose is to provide a method for evaluating damage to steel cables that can quantitatively measure and evaluate damage to steel cables.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a damage measuring machine that can run along a steel cable, and this damage measuring machine includes a magnetizer that magnetizes the steel cable, and a magnetizer that magnetizes the steel cable. A magnetometer is provided to detect the magnetic flux density generated in the steel cable due to magnetization, and the relationship between the cross-sectional area and magnetic flux density of a steel cable made of the same material as the steel cable is measured in advance, and the magnetizer is installed at each point of the steel cable. magnetize the steel cable, detect the magnetic flux density generated by this magnetization with the magnetometer, determine the cross-sectional area of the steel cable from the detected magnetic flux density, and calculate the difference between this determined cross-sectional area and the cross-sectional area of the steel cable when new. The damage to the steel cables is evaluated by determining the reduction in cross-sectional area by comparison.

[Function] In this method, the amount of damage to the steel cable whose damage is to be measured is determined as an absolute amount from the relationship between the magnetic flux density obtained by pre-measurement and the cross-sectional area of the steel cable. can be evaluated in terms of

[Example code] Examples of the present invention will be described below.

In FIG. 1, 1 is a steel cable, and 2 is a traveling damage measuring device attached to the steel cable 1. The damage measuring device 2 includes a magnetizer 3 that magnetizes the steel cable 1 and generates a magnetic flux along its longitudinal direction;
and a detection coil 4 that detects the induced voltage due to the magnetic flux generated in the steel cable 1. The magnetizer 3 is composed of a yoke 5 and a magnetizing coil 6, and the magnetizer 3 is a variable current type for changing the strength of magnetization in the magnetizing coil 6. A power source 7 is connected, and this power source 7 is capable of continuously outputting current of both positive and negative polarities.

8 is a magnetometer that integrates the induced voltage output by the detection coil 4 to measure magnetic flux density, and 9 is a recorder that draws a magnetization curve using the outputs of the power source 7 and the magnetometer 8. Further, 10 is a position detector that detects a measurement position with respect to the steel cable 1.

Fig. 2 is a diagram obtained by measuring the relationship between the magnetic flux density and the cross-sectional area of the steel cable when a steel cable made of the same material as the steel cable 1 is magnetized in advance under certain conditions. A certain proportional relationship holds between the area and the area.

Therefore, the damage measuring device 2 is moved along the rope 1, and the
Place A where there is. At this point, the steel cable 1 is magnetized by the magnetizer 3 under the same conditions as described above, and the magnetic flux density generated by this magnetization is measured by the magnetometer 8. The cross-sectional area of the steel cable 1 at point AO is determined by comparing this magnetic flux density with the magnetic flux density in the graph of FIG. And this cross-sectional area and steel cable 1
Compare the cross-sectional area when it is new, that is, when it is undamaged.

For example, the cross-sectional area of the steel cable 1 when new is 51, and A is determined based on the magnetic flux density. If the cross-sectional area at the point is 82, the cross-sectional area of the steel cable 1 has a decrease of S, -S2,
This decreased amount is the missing amount caused by corrosion, abrasion, wire breakage, etc. Therefore, this decreased amount is A. The absolute amount of damage at a point can be determined.

In this way, damage at each point A, A2, . . . of the steel cable 1 is quantitatively measured and evaluated by moving the damage measuring device 2.

Describing the specific structure of the damage measuring device 2, this is constructed as shown in FIGS. 3 to 6. That is, 11 is a base, and the magnetizer 3 is provided on this base 11.

This magnetizer 3 has a movable lid 14 rotatably mounted on a fixed base 12 via a hinge 13, and split yokes 5a and 5b are provided inside the fixed base 12 and the movable lid 14. A buckle 15 for locking the movable lid 14 is provided between the fixed base 12 and the movable lid 14.

A support 16 is provided at both ends of the upper surface of the base 11, a rotary plate 17 is rotatably provided on the support 16, and a pair of rollers 1g and 19 are rotatably attached to the front surface of the rotary plate 17. . Further, a spring 20 is stretched between the rotating plate 17 and the base 11, and the spring 20 elastically urges the rotating plate 17 in one rotation direction.

When attaching the damage measuring device 2 to the steel cable 1, use the buckle 15.
, open the movable lid 14, and attach the steel cable 1 to the rollers 18 and 19.
At the same time, the steel cable 1 is positioned between the fixed base 12 and the movable lid 14, and the detection coil 4 is wound around the outer circumference of the steel cable 1 without contacting the circumferential surface thereof.

Thereafter, the movable lid 14 is closed and latched with the buckle 15.

The rollers 18 and 19 contact the steel cable 1 from above and below with appropriate pressure due to the biasing force of the spring 20, and therefore the damage measuring device 2 is stably supported. The damage measuring device 2 can be smoothly run along the steel cable 1.

[Effects of the Invention] As explained above, according to the present invention, damage to steel cables can be quantitatively grasped and evaluated not as a mere relative amount but as an absolute amount.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the present invention, Fig. 2 is a graph showing the relationship between the cross-sectional area of a steel cable and magnetic flux density, Fig. 3 is a front view showing an example of a damage measuring device, and Fig. 4 is a plan view as well. , FIG. 5 is a front view of the magnetizer portion of the damage measuring device, and FIG. 6 is a structural diagram thereof. 1... Steel cable, 2... Damage measuring device, 3... Magnetizer,
8... Magnetometer.

Claims (1)

[Claims] A damage measuring machine that can run along the steel cable is installed, and this damage measuring machine is equipped with a magnetizer that magnetizes the steel cable and a magnetometer that detects the magnetic flux density generated in the steel cable due to the magnetization. The relationship between the cross-sectional area of the steel cable and the magnetic flux density is measured in advance, and the steel cable is magnetized by the magnetizer at each point of the steel cable, and the magnetic flux density generated by this magnetization is detected by the magnetometer. The method is characterized in that the cross-sectional area of the steel cable is determined based on the detected magnetic flux density, and the determined cross-sectional area is compared with the cross-sectional area of the steel cable when it is new to determine the decrease in the cross-sectional area and the damage to the steel cable is evaluated. Damage evaluation method for steel cables.