JPH03268850A - Method for measuring bulging rate of continuously cast slab - Google Patents

Abstract

PURPOSE:To measure accurate displacement without receiving effect of adjacent sensors by exciting primary coils in plural eddy current type range finders while scanning and measuring bulging quantity. CONSTITUTION:A primary exciting circuit 3 exciting a primary coil 8 is always made under exciting condition and displacement signal detecting circuit 6 is always made under data reading condition. A primary coil change-over circuit 4 is worked with a micro-processor or 2 to excite only the primary coil 8 in the corresponding eddy current sensor 1. By working a secondary coil change-over circuit 5, the corresponding secondary coil 9 is connected with the displacement signal detecting circuit 6. The eddy current is caused to flow on surface of a continuously cast slab 7 by alternating magnetic flux generated with the primary coil 8, and the magnetic flux is generated to direction cancelling the alternating magnetic flux. AC current generated to a secondary coil 9 with this flux, is detected with the displacement signal detecting circuit 6 and transmitted to the micro processor 2. The bulging quantity in the continuously cast slab 7 is obtd. from the detected displacement signal. Plural eddy current sensors 1 periodically scans to measure the bulging quantity of continuously cast slab 7 corresponding to each position.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for measuring the amount of bulging in a continuously cast slab.

(Prior Art) Conventionally, the amount of bulging of a continuously cast slab has been measured using a contact distance or an eddy current distance meter for the purpose of controlling the internal quality of the slab.

A contact distance meter brings the contact of the distance meter into contact with the surface of the slab and measures the amount of bulging from the amount of movement of the contact. However, with this method, measurement errors due to thermal expansion or contact There are problems such as the occurrence of defects on the surface of the slab due to poor rotation.

Eddy current distance meters measure the amount of bulging by placing eddy current sensors around the slab.

This method uses Vortex T! Due to the alternating current in the primary coil in the L flow sensor, the alternating magnetic flux generated in the - secondary coil causes
An 11I current flows on the surface of the slab, and this eddy current lfc generates magnetic flux in a direction that cancels out the alternating magnetic flux generated in the primary coil. This magnetic flux produces an alternating current 7ATXm in the secondary coil within the eddy current sensor. The alternating current generated in the secondary coil is detected by a displacement signal detection circuit, and the amount of bulging is determined based on the detected displacement signal. The magnitude of the eddy current flowing on the slab surface changes depending on the distance between the secondary coil and the slab surface, so by knowing the change in the alternating current generated in the secondary coil, the amount of bulging of the continuously cast slab can be determined. can be measured.

(tJAM to be solved by the invention) However, the eddy current distance meter cannot accurately measure the amount of bulging due to the influence of leakage magnetic flux from the adjacent sensors when multiple adjacent sensors are excited simultaneously. Although it is possible to prevent the influence of leakage magnetic flux from adjacent sensors by changing the excitation frequency of each sensor, it is necessary to increase the frequency ratio between adjacent sensors in order to prevent the influence of leakage magnetic flux. In this case, since the frequency of each sensor is different, the magnetic flux penetration depth of each sensor is different, resulting in a difference in the sensitivity for detecting the amount of bulging.Also, as the number of sensors increases, the excitation frequency on the primary coil side becomes considerably high. There is a problem that the sensor sensitivity becomes unstable.

(Means for Solving the Problems) The present invention solves the above problems and provides a bulging amount measuring method that can accurately measure displacement without being influenced by adjacent sensors even though multiple sensors are arranged. In this method, a plurality of eddy current distance meters are arranged in the width direction and thickness direction of a slab to be cast in continuous casting equipment, and the amount of slab bulging is measured by the output of each eddy current distance meter. This is a method of measuring the amount of bulging in a continuously cast slab by exciting the primary coil of each eddy current distance meter while scanning it.

(Function) The system according to the present invention includes an eddy current sensor microprocessor, a primary coil excitation circuit, a secondary coil switching circuit, a secondary coil switching circuit, and a displacement signal detection circuit. Note that the eddy current sensor incorporates a primary coil and a secondary coil.

In measuring the amount of bulging, the primary excitation circuit that excites the -order coil is kept in a constantly excited state, and at the same time, the displacement signal detection circuit is also kept in a state where it always reads data. In this state, the micropro sensor activates the primary coil switching circuit to excite only the primary coil of the eddy current sensor corresponding to the position where the amount of bulging is to be measured, and at the same time activates the secondary coil switching circuit, - A secondary coil corresponding to the next coil is connected to a displacement signal detection circuit.

The alternating magnetic flux generated in the primary coil causes a vortex 1 flow to flow on the surface of the continuously cast slab, and this vortex ii current generates magnetic flux in a direction that cancels out the alternating magnetic flux generated in the primary coil. This magnetic flux produces an alternating current in the secondary coil. The alternating current generated in this secondary coil is detected by a displacement signal detection circuit, and sent to the microprocessor.The microprocessor determines the amount of bulging of the continuously cast slab based on the displacement signal detected by the displacement signal detection circuit. seek. Furthermore, the amount of bulging corresponding to each position is measured by scanning the plurality of eddy current sensors arranged at regular intervals.

In this way, by scanning and selectively exciting only the primary coil of a single eddy current sensor among multiple eddy current sensors, it is possible to The amount of bulging of continuously cast slabs can be accurately measured without being affected by the leakage magnetic flux of the secondary coil.

(Example> Examples of the present invention will be described below.

Figure 1 is a schematic diagram of the system of the present invention, where ■ is a vortex '1ii
i! 13 is a primary coil excitation circuit, 4 is a primary coil switching circuit, 5 is a secondary coil switching circuit, 6 is a displacement signal detection circuit, and 7 is a continuously cast slab. FIG. 2 is a diagram showing the relationship between the primary coil and the secondary coil in the eddy current sensor, where 8 represents the primary coil and 9 represents the secondary coil.

When measuring the amount of bulging of a continuously cast slab, the primary Fil+magnetic circuit 3 that excites the negative coil 8 is always kept in an energized state, and the displacement signal detection circuit 6 is also kept in a state that always reads data. In this state, Micro Pro Sensor 2
The primary coil switching circuit 3 is operated, and the continuously cast slab 7
While exciting only the primary coil 8 of the eddy current sensor 1 corresponding to the position where the amount of bulging is to be measured,
The secondary coil switching circuit 5 is activated, and the secondary coil 9 corresponding to the -secondary coil 8 is connected to the displacement signal detection circuit. In this way, the alternating magnetic flux generated in the primary coil 8 causes eddy electric residue to flow on the surface of the continuously cast slab 7, and this eddy current generates magnetic flux in a direction that cancels out the alternating magnetic flux generated in the primary coil 8. This magnetic flux generates an alternating current in the secondary coil 9. The alternating current generated in the secondary coil 9 is detected by the displacement signal detection circuit 6 and sent to the microprocessor-2. The amount of bulging of the continuously cast slab was determined based on the displacement signal detected by the displacement signal detection circuit 6 using the micropro sensor 2. Furthermore, the amount of bulging of the continuously cast slab corresponding to each position was measured by scanning the plurality of eddy current sensors arranged at regular intervals.

(Effects of the Invention) As explained above, the present invention has a plurality of vortex flow sensors arranged in the width direction and thickness direction of a continuously cast slab.
By selectively exciting only the primary coil of a single eddy current sensor, continuous cast slabs can be continuously cast at the same frequency without being affected by leakage flux from adjacent coils, regardless of the spacing between the eddy current sensors. The amount of bulging can be measured accurately. Further, by associating the scan position with the displacement signal using a microprocessor, the amount of bulging in the width direction and thickness direction of the continuously cast slab can be measured.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the system according to the present invention, and FIG. 2 is a diagram showing the relationship between the primary coil and the secondary coil in the eddy current sensor. 1-1 vortex flow sensor, 2 microprocessor, 3-
Primary coil excitation circuit, 4th coil switching circuit, 5
Secondary coil switching circuit, 6 displacement signal detection circuit, 7 continuous cast slab, 8 - primary coil, 9 - secondary coil.

Claims (1)

[Claims] In a method in which multiple eddy current distance meters are arranged in the width direction and thickness direction of a slab to be cast in continuous casting equipment, and the amount of slab bulging is measured by the output of each eddy current distance meter, each eddy current A method for measuring the amount of bulging of a continuously cast slab, characterized by exciting the primary coil of a distance meter while scanning it.