JPS6110753A - Measurement of flux packing rate - Google Patents

Abstract

PURPOSE:To enable highly accurate and stable measurement, by varying impedance detected when a flux-filled wire (FW) is passed through a coil. CONSTITUTION:When a metal wire is put into a coil through which AC current flows, a sort of induced current call as eddy current is generated. This eddy current changes depending not only on the level of the current applied to the coil but also on discontinuous portions of metal and variations in the shape of a sample when the current is constant. Utilizing the nature of the eddy current, changes in the thickness of skin metal can be caught as variations in the impedance (IP). So, first, FW carried with a reference thickness is inserted into a specified coil to measure IP at a specified frequency. Then, FW to be measured is measured on the same condition as the preceding one and the resulting IP is compared with a reference IP. Thus, the thickness at the part measured is judged and moreover very accurate calculation of the ratio of the flux can be done from the unit weight of skin metal at the measured part and the total weight per unit of the wire at the measured part.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for non-destructively measuring the flux filling rate of a flux-cored wire, and in particular, the present invention relates to a method for non-destructively measuring the flux filling rate of a flux-cored wire, and in particular, it is possible to always stably and accurately measure the flux filling rate without any fluctuation in the measurement situation. The present invention relates to a flux filling rate measurement method that can be used to measure the flux filling rate.

[Prior Art] Flux-cored wires (hereinafter simply referred to as wires), which are formed by filling a flux into a metal sheath formed by curving a steel strip or a seamless pipe, are made by filling the outside of the flux with a sheath. Since it is covered with metal, it is not possible to inspect the flux filling condition from the outside. Therefore, when inspecting the flux filling condition, for example, cut a certain length of wire, extract the flux from the outer metal, and measure the unit length. Destructive testing methods can be considered to find out the flux filling rate (hereinafter simply referred to as flux rate) by actually measuring the weight of flux relative to the total weight of the wire, but such batch testing methods are in themselves impractical. In terms of efficiency and yield, it is not possible to cut the wire in the middle, and the inspection is inevitably biased toward the end, resulting in unsatisfactory accuracy. Therefore, there is a need for the development of a continuous, non-destructive method for inspecting wires. That is, as a non-destructive testing method, for example, as shown in Japanese Patent Application Laid-Open No. 53-46450, the wire drawing speed during wire diameter reduction processing is continuously measured, and the fact that the drawing speed is inversely proportional to the wire thickness is utilized. There is a method of estimating the change in flux rate by measuring the electrical resistance between any two points in the longitudinal direction of the wire, as shown in Japanese Patent Application Laid-Open No. 57-32894. There are known methods for measuring the magnitude of .

[Problems to be Solved by the Invention] However, the above measurement method has the following problems. That is, in the former measurement method, the wire diameter may change due to wear of the drawing die, etc., so the accuracy of estimation from the wire drawing speed becomes low. In addition, the rotational unevenness of the pulling drive motor also affects the pulling speed, so if you simply capture the change in the pulling speed,
It is difficult to directly measure the change in velocity as a change in flux rate. In the latter measurement method, the measuring terminal of the measuring device is brought into direct contact with the outer metal of the wire to measure the electrical resistance between two measurement points, and the flux rate changes depending on the difference between the reference electrical resistance value and the measured electrical resistance value. However, since the contact between the outer metal and the measurement terminal is not always perfect, it is not possible to detect only the change in electrical resistance and directly interpret it as a change in flux rate. In addition, this measurement method requires the measurement terminal to be brought into direct contact with the outer metal of the wire.

There is also a problem in that measurement cannot be performed unless the wire being pulled out by the commander is temporarily stopped, and production must be stopped.

As described above, conventional measurement methods do not always provide highly accurate measurement values. A flux filling rate measurement method that can stably obtain highly accurate measurement values is desired.

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned circumstances, and aims to provide a measuring method that can measure the filling rate of flux with high precision and stability. It is something.

That is, the means for solving the problem is to measure the flux filling rate based on the change in impedance detected when a flux-cored wire is passed through the coil.

[Operation] That is, the flux filling rate measurement method of the present invention attempts to determine the amount of flux filled in the outer metal shell by the thickness of the outer metal shell.The basic principle is that the outer diameter of the wire is kept constant. In this case, the following relationship is used between the thickness of the outer metal shell and the amount of flux filled. In other words, a wire that is drawn while being restricted on the outside diameter side has a tendency to bulge toward the inside diameter side, so if the amount of flux filled is small, the thickness of the outer metal will tend to increase, and vice versa. If the amount of 7lux is large, even if the outer metal layer tries to become thicker, the flux becomes an obstacle and the wall thickness becomes thinner. This method utilizes the fact that the thickness of the metal shell increases or decreases depending on the amount of flux filled, and this relationship is shown in a graph as shown in FIG. In the graph, wires formed with outer diameters of 1.2φ, 1.6φ, and 2.4φ (sheath metal: JIS Z 31415PC
E band steel size: thickness 0.8 mm, @12+n+
The relationship between the thickness of the outer skin metal and the flux rate is shown for the curved material used. In other words, as is clear from the graph, the thicker the outer metal wall, the lower the flux rate, and conversely, the thinner the wall thickness, the higher the flux rate.

It becomes possible to easily know the flux rate simply by measuring the wall thickness of the outer skin metal.

On the other hand, when measuring the wall thickness of such a metal shell, it is said that stable measurement results can be obtained by measuring by electrical means. We focused on a method that utilizes the induction effect. According to this method, wall thickness can be measured using the following principle.

In other words, when a metal wire is placed in a coil through which an alternating current is passed,
The alternating magnetic flux HP generated by the alternating current induces a kind of eddy current in the metal wire, and this eddy current also generates a secondary magnetic flux Hs. This magnetic flux Hs is in the opposite direction to the magnetic flux Hp mentioned above and acts in a direction to reduce it, so that the back electromotive force of the coil decreases and the apparent impedance of the coil decreases. This eddy current changes depending on the magnitude of the current applied to the coil, but if the current is kept constant, it will also change due to discontinuous parts of the metal or changes in the shape of the sample. Therefore, by utilizing the properties of the eddy current described above, changes in the thickness of the outer skin metal can be interpreted as changes in impedance occurring in the coil.

That is, as the thickness of the outer metal layer increases, a correspondingly larger eddy current is generated, and the impedance of the coil decreases significantly, and conversely, as the thickness decreases, the drop in impedance also decreases. In this way, there is a close relationship between the thickness of the outer metal part of the wire and the coil impedance. Therefore, a flux-cored wire with a standard wall thickness is inserted into a specific coil, the coil impedance is measured at a specific frequency, and the impedance is taken as the standard impedance. If you compare the measured impedance obtained by measuring the actually drawn wire under the same conditions as above with the standard impedance above, you can find out how much the wall thickness of the actual measured part is compared to the standard wall thickness. It can be inferred that it is formed by That is, it is possible to know how much thicker or thinner the wall is than the standard thickness based on the difference between the standard impedance and the measured impedance. When the thickness of the sheath metal is measured in this way, the unit weight of the sheath metal at the measurement location and the total weight per unit of the wire at the measurement location can be known, so the flux rate at the measurement location can be calculated extremely accurately. In particular, in the present invention, the coil is placed as part of the resonant circuit and is placed in a non-contact state with the wire, and the wire inserted into the coil is measured electrically and in a non-contact manner, so that stable measured values can be obtained. In this case, it is possible to configure an LC oscillation circuit in which the oscillation intensity changes in response to changes in coil impedance by adding a transistor or the like to the resonant circuit, and the oscillation intensity can be extracted as a DC voltage using a rectifier circuit. . The measurement frequency that is important for measurement is the oscillation frequency, which can be adjusted by the value of the capacitor combined with the coil.

The resonant circuit applied to the present invention may be a parallel resonant circuit as shown in FIG. 2, or a series resonant circuit. In this way, it is necessary to select an appropriate frequency for the oscillator, which uses a coil and a capacitor as a resonant circuit, depending on the cross-sectional shape, wall thickness, and wire diameter of the wire.For example, use a seamless wire as shown in Figure 3. .

In addition, when the thickness of the outer skin metal l is about 0.3 ram, changes in the flux rate can be clearly known by using a frequency of several kilohertz. In addition, in the case of a wire with a seam as shown in Fig. 4, since the outer sheath metal l is open in the circumferential direction, taking into account that eddy currents will circulate around the inner surface, the value is higher (10s) than in the case of Fig. 3. kHz) is required. Also, if the wall thickness is thick, the measurement is performed in a low frequency band, and if the wall thickness is thin, the measurement is performed in a high frequency band, and the measurement of the outer metal can be carried out extremely stably.

[Example] When a flux-cored wire was measured using the measuring method according to the present invention, the following results were obtained.

Ta.

Conditions Outer metal: JIS Z 31415PCE (original size) Q, 8 rmva thickness x 12 shoes lII! 1g measurement wire diameter: 1.6mm ◆ Wire cross-sectional shape: Figure 3 Flux type: Titania type Detection coil: Inner diameter 6IIIlφ, width 10m.

Oscillation circuit with 2000 turns of 0.08 m x φ polyurethane copper wire: Figure 2. When measured under the above conditions, results as shown in the graph of Figure 5 were obtained.

[Effects of the Invention] Since the present invention is configured as described above, electrical measurement can be performed from the outside without destroying the wire, and there is no need to make contact between the wire and the measurement terminal, making it possible to perform stable and reliable measurement. Can be established with high precision.

As a result, without stopping the wire processing equipment? This makes it possible to perform continuous measurements even when the ear is running, increasing productivity and improving yield.

　 　 　 　 　 　 　 　 　 　 　 　

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between the thickness of the outer skin metal and the flux rate, and Fig. 2 is a graph showing the relationship between the thickness of the outer skin metal and the flux rate. is a graph illustrating a cross section of a wire with 8 squares, and FIG. 5 is a graph showing experimental results. l...Sheath metal

Claims (2)

[Claims] (1) A flux filling rate measuring method characterized by measuring the flux filling rate based on the change in impedance detected when a flux-cored wire is passed through a coil. (2) A flux filling rate measuring method characterized in that the coil impedance detected when a flux-cored wire is passed through the coil of an LC oscillation circuit is detected as an oscillation output, and the flux rate is measured as an electric signal.