JP3476169B2 - Detecting device for powder filling rate of powder filling tube - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powdery or granular material filling rate detecting device for a powdery or granular material filling tube.

[0002]

2. Description of the Related Art A powder-filled tube is, for example, a carbon steel, stainless steel, aluminum alloy, or other metal tube, and contains, for example, a flux for welding, an oxide superconducting material, an additive for molten steel, or the like. It is filled with a body, granules, or a mixture of powder and granules. For example, if the wire diameter is
The flux-cored wire for welding 0.8 to 2.4 mm is manufactured as follows. That is, the steel pipe is vibration-filled with flux, or a metal plate having a U-shaped cross section is formed into an O-shaped cross-section tube and the flux is filled from the wedge-shaped opening before the pipe is formed. Butt against each other and weld. The tube filled with the flux is further reduced in diameter by 90% or more by rolling or drawing.

However, in the flux-cored wire produced by these methods, the flux may not be uniformly filled over the entire length in the longitudinal direction of the steel pipe,
In the worst case, some areas are not filled. When a flux-cored wire having a non-uniform flux filling rate or a flux-missing portion is used for welding as described above, welding defects such as pits and blowholes may occur at the welded portion, and therefore the above-mentioned flux-cored wire may not be formed. Accurate measurement of the flux filling rate in the manufacturing process is required.

In Japanese Patent Laid-Open No. 61-8656, a reference coil of the same kind as the flux-cored wire to be inspected, which has passed a reference wire having a desired flux filling rate, and a flux-cored wire to be detected are continuous. A bridge-comparison type filling rate detection, in which a detection signal representing the deviation of the impedance of the detection coil with respect to the impedance of the comparison coil is obtained as a flux filling rate deviation signal by phase detection by connecting a bridge with a detection coil that passes through A device is disclosed.

[0005]

Although the reference wire passed through the comparison coil is stationary and fixed, the flux-cored wire to be inspected is moving and has just been processed. There is a temperature difference. In addition, the moving speed and the temperature are changed by changing the operating conditions. These fluctuations or changes cause a so-called drift in the detection signal, which reduces the accuracy of defective filling rate detection. An object of the present invention is to improve the reliability of filling rate inspection.

[0006]

The present invention comprises a detection coil (2) through which a powdery or granular material-filled pipe (1) to be conveyed passes, and an electric circuit (3) for detecting the impedance of the detection coil. In the powder / granule filling rate detecting device for powder / granular filling tube, means (4a to 4g) for calculating a time series smoothed value of the detection signal of the impedance corresponding level generated by the electric circuit (3); Means (4h) for generating a measurement signal representing the difference of the detection signal with respect to a smoothed value; and comparing the measurement signal with a set value,
It is characterized by comprising means (4j) for generating an alarm signal when the difference represented by the measurement signal exceeds a set value. In addition, in order to facilitate understanding, in parentheses, the symbols of the corresponding elements of the embodiments shown in the drawings and described later are added for reference.

According to this, the powder and granular material filling pipe to be conveyed
Although the moving speed, temperature, vibration, etc. of (1) change depending on the operating conditions,
It is almost constant if there is no change in operating conditions.
While the packing rate of powder and granules in (1) is equivalent to the reference wire (3b),
The detection signal of the electric circuit (3) has a substantially constant level of a certain value (drift). In the present invention, means (4a ~ 4g) calculates the time series smoothed value corresponding to this level, means (4h), the measurement signal representing the difference of the detection signal of the electric circuit (3) to this time series smoothed value. To occur. Therefore, the level of the measurement signal is obtained by correcting the detection signal of the electric circuit (3) for the drift amount determined by the operating condition, and the reliability of the measurement signal indicating the filling rate of the granular material is high.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The filling rate detecting device of the present invention further comprises:
Means (4j) for comparing the measurement signal with a set value and generating an alarm signal when the difference represented by the measurement signal exceeds the set value; and
Means to stop updating the time-series smoothed value while there is an alarm signal (4
k, 4L); According to this, an alarm signal is generated when the filling rate is abnormal, and the alarm signal activates the marker to spray paint indicating a defective portion on the filling pipe (1) downstream of the detection coil. Treatment allowances can be made. If an alarm signal is generated, that is, if the filling rate is abnormal, if the time-series smoothed value is continuously updated, the time-series smoothed value shifts to the detection signal level of the defective filling rate, resulting in an error and the defective filling rate The point of passing through the detection coil causes the defective filling rate detection to substantially stop functioning until the time-series smoothed value returns to the drift equivalent value of the normal point. In the present invention, since the means (4k, 4L) stops updating the time-series smoothed value while the alarm signal is present, the time-series smoothed value remains at the drift value while the location of the defective filling rate passes through the detection coil. The above problem does not occur because the increase in the defective filling rate does not occur. That is, normal detection of defective filling rate continues continuously.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. The detection coil 1 and the comparison coil 3c are connected to the bridge circuit 3a of the measuring head, and the welding flux-cored wire 1 (product) in which the detection coil 1 is filled with flux to be thinned (thinned) is continuous. Then, move at high speed. This wire 1 is the inspection object of the filling rate defect, and the comparison coil 3c
The reference wire 3b passing through is the wire 1 previously manufactured.
The non-defective part is cut and is fixed.

An alternating voltage of 125 KHz is applied from the power amplifier 3e to the bridge circuit 3a. The voltage generated at the measurement signal output end of the bridge circuit 3a is level-adjusted through the attenuator 3f and the tuning amplifier 3g, and then given to the phase detector 3h. To the phase detector 3h, the phase shifter 3i gives a signal obtained by delaying the AC signal of 125 KHz by a predetermined phase, and the phase detector 3h represents the impedance of the detection coil 2 of the output voltage of the bridge circuit 3a. The component signals X and Y are extracted and output. These two
By applying the component signals X and Y to the oscilloscope,
A curve representing the impedance appears on the X, Y display surface. A signal Y having a high correlation with the thickness of the wire 1 is output from the detection circuit 3 through the low pass filter 3j. This signal Y is the measurement output of the conventional bridge-comparison type filling factor detection device, and the level of the signal Y corresponds to the deviation of the wall thickness of the inspection target wire 1 from the wall thickness of the reference wire 3b. As described above, the drift component is included in this signal Y.

The correction circuit 4 is added according to the present invention. A speed signal (analog voltage) representing the moving speed Vs of the wire 1 to be inspected is applied to the V / F converter 4b, and the V / F converter 4b generates electricity with a frequency (pulse rate) proportional to the speed Vs. Generates a pulse (speed synchronization pulse). The peak hold circuit 4a is reset by this (speed falling edge) pulse, so that the peak
The output voltage of the hold circuit 4a rises in the same manner as the input signal Y rises, but stays at the starting level for one period of the speed synchronizing pulse while the input signal Y rises. The step-like change is in synchronization with the sync pulse. When the signal Y rises and falls during one cycle, the peak is reached until the end of the cycle.
It becomes the value.

At the rising edge of the speed synchronizing pulse (ie, just before the peak-hold circuit 4a is reset),
The sample hold circuit 4c takes in and holds the hold voltage of the peak hold circuit 4a. That is, sampling is performed. Immediately after the end of sampling (in response to the falling edge of the speed sync pulse), the A / D converter 4
Start the digital conversion of the voltage sampled by d,
The digital data is given to the accumulator 4e. The accumulator 4e is
The digital data (value of) given this time is added to (the value of) the accumulated data held therein, and the data representing the obtained sum is updated to the accumulated data. Therefore, the accumulator 4e
Is the signal Y sampled at the period of the speed synchronization pulse.
Accumulate (the level of).

On the other hand, the 8-bit counter 4f counts up the speed synchronizing pulse. When the count value reaches 64, this counter generates a carry signal to set the count value to 0.
It is a circulation counter that is initialized to 0 and repeats counting up from 0, and a carry signal of 1 pulse is generated each time 64 speed synchronization pulses arrive. This carry
The signal is given to the accumulator 4e. The accumulator 4e, in response to the carry signal, latches the currently held accumulated data in its output latch and clears the accumulated data. Therefore, the accumulator 4e receives 6 speed synchronization pulses.
The total of 64 sampling values during 4 generations is output (stored in the output latch). Data representing 1/64 of the value represented by the latch data of the accumulator 4e (upper bits from the lower 8 bits of the accumulated data, discarding the lower 8 bits), that is, a speed synchronization pulse The average value of the sampling data while 64 are generated are given to the D / A converter 4g, converted into an analog voltage, and given to the differential amplifier 4h.

The differential amplifier 4h is a peak-hold circuit 4
A signal Y output by a is subtracted from the average value signal (time-series smoothed value) given by the D / A converter 4g to generate a measurement signal of a level, which is passed through the low-pass filter 4i.
Output. This measurement signal is called the filling rate signal,
To be precise, it is a signal of a level corresponding to the deviation of the thickness of the inspection target wire 1 from the thickness of the reference wire 3b. This level is a value obtained by subtracting the average value of the signal Y during the generation of 64 speed synchronizing pulses from the signal Y, and the average value is the drift amount determined by the operating conditions. Highly reliable showing the packing rate of powder and granules.

The comparator 4j compares the measurement signal with a set level (a threshold value for determining whether the filling rate is good or bad). If the level of the measurement signal is higher, a high level H (filling is insufficient; When is high, a low level L (good filling rate; normal), a binary signal (alarm signal) is generated, and this is given to a marker (not shown) downstream of the detection coil 2. The marker jets paint onto the wire 1 while the binary signal is H to mark it.

If the state where the level of the measurement signal is higher (insufficient filling; abnormal) continues, that is, if the level of the signal Y output from the detection circuit 3 continues to be high, it is assumed that it continues to be taken into the accumulator 4e. And the level of the average value signal rises, and the argument level (D
/ A converter 4g output level) rises, and the output level of the differential amplifier 4h drops to a level indicating normality even at the place where the filling is insufficient (the increase in the signal level of the insufficient filling portion is regarded as a drift amount). . In order to avoid this, in the present embodiment, when the comparator 4j outputs a signal of high level H (insufficient filling; abnormal), the AND gate 4L is turned off (the speed synchronizing pulse is cut off) via the inverter 4k. , The data transfer to the accumulator 4e by the A / D converter 4d is stopped, and the count-up of the 8-bit counter 4f is stopped. As a result, when the comparator 4j outputs a signal of high level H (insufficient filling; abnormal), that is, when insufficient filling is detected, the accumulation operation of the accumulator 4e and the update of the output data (latch output) are performed. Stop and the drift compensation signal (D / A converter) applied to the differential amplifier 4h.
The output voltage of 4 g) is maintained as it is. This state continues until the insufficiently filled portion has passed through the detection coil 2, and the comparator 4j continues to output a high level H (insufficiently filled; abnormal) signal.

When the insufficiently filled portion has passed through the detection coil 2, the output of the comparator 4j turns to L, which turns on the AND gate 4L (passes the speed synchronizing pulse) and synchronizes with the speed synchronizing pulse. Then, the A / D converter 4d starts digital conversion of sampling data and transfer to the accumulator 4e, and the counter 4f restarts counting up.
The average value update resumes.

As described above, a highly reliable measurement signal in which the drift amount determined by the operating conditions is automatically corrected can be obtained from the differential amplifier 4h through the low-pass filter 4i. Further, since the update of the average value is automatically stopped when the insufficient filling is detected, the insufficient filling signal (the output H of the comparator 4j; the alarm signal) is continuously generated while the insufficient filling continues, and the reliability It is highly likely.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an exemplary embodiment of the present invention.

[Explanation of symbols]

1: Welding flux-cored wire to be inspected 2: Detection coil 3a: Bridge circuit 3b: Reference wire 3c: Comparison coil 4h: Differential amplifier 4j: Comparator

Front page continuation (72) Inventor Masayuki Ubara 1-12-8 Sansuji, Taito-ku, Tokyo Giken Kogyo Co., Ltd. (56) References JP 63-236956 (JP, A) JP 62 -84897 (JP, A) JP 61-47554 (JP, A) JP 61-10753 (JP, A) JP 61-8656 (JP, A) (58) Fields investigated (Int.Cl) . ^7, DB name) B23K 35/40

Claims (2)

(57) [Claims] 1. A powdery or granular material filling rate detecting apparatus for a powdery or granular material filling pipe, comprising: a detection coil through which a powdery or granular material filling pipe passes; and an electric circuit for detecting the impedance of the detection coil. Means for calculating a time-series smoothed value of the detection signal of the impedance-corresponding level generated by the circuit; and means for generating a measurement signal representing a difference of the detection signal with respect to the time-series smoothed value. A granular material filling rate detection device for a granular material filling pipe. 2. Means for comparing the measurement signal with a set value and generating an alarm signal when the difference represented by the measurement signal exceeds the set value.
And a means for stopping the updating of the time-series smoothed value while the alarm signal is present;