JPH0814938A - Discrimination apparatus - Google Patents

Abstract

PURPOSE:To discriminate an object, to be measured, always stably even when the change cause of a measured value exists by a method wherein a comparison circuit which compares the measured value with a threshold value is installed and a threshold- value adjustment means which adjusts the threshold value on the basis of measured value of a plurality of objects to be measured is installed. CONSTITUTION:A magnetic flux which has been transmitted through a metal plate is detected by a detection coil 33, a detected magnetic flux is amplified 34, and an amplified magnetic flux is input to a comparison circuit 35 and an A/D converter 41. An analog signal which represents the measured value of the magnetic flux which is output from the circuit 34 is converted into a digital signal by the converter 41, and the converted measured value is stored in a memory 42. When a latest measured value is designated as Xn [where (n) represents the number of measuring operations from a measuring start], e.g. 16 measured values Xn, Xn-1,...Xn-15, are stored in the memory, and the measured value Xn-15 which is oldest is erased when a new measured value is to be stored. Their mean value is found by an average arithmetic part 43, and it is input to a threshold-value creation part 44. A threshold value is adjusted by the creation part 44, and it is A/D-converted 45 so as to be compared 35. After that, the threshold value is adjusted sequentially according to a change in the measured values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention sequentially measures a predetermined physical quantity of an object to be measured, for example, thickness, weight, dimensions, etc., of a plurality of objects to be measured, and the object to be measured is measured according to the measured values. To
For example, the present invention relates to a discriminating device that discriminates into a plurality of groups such as good and defective.

[0002]

2. Description of the Related Art Conventionally, the discriminating apparatus as described above has been used in a wide variety of fields. Here, as an example thereof, an example of a device for detecting the overlapping of two metal plates will be described.
FIG. 2 is a schematic view showing an example of the two-metal-plate overlapping detection device. For example, on the most upstream side of a line for bending or punching a metal plate, a large number of stacked metal plates 1 are sucked up one by one with a suction cup 2 and then fed to the line. It At that time,
As indicated by the one-dot chain line, when two metal plates are lifted by the suction cup 2 while being attracted to each other and supplied to the line as they are, a large load is applied to the processing die for processing the metal plates, and There is a risk of damage to the mold, and in order to avoid this, it is detected that two metal plates 1 have been lifted, and if two metal plates are lifted, the metal plates are not fed to the line and removed sideways. It is necessary to take measures such as putting it down.

Therefore, here, there is provided a two-metal-plate overlapping detection device 3 for detecting that two metal plates have been lifted. This two-metal-plate stacking detection device 3 is provided with a drive coil 31 and a coil drive circuit 32 for driving the drive coil 31, and the coil drive circuit 32 drives the drive coil 31 and the drive coil 31 outputs a predetermined signal. Generates an alternating magnetic flux. A detection coil 33 is arranged to face the drive coil 31, and the magnetic flux generated in the drive coil 31 and transmitted through the metal plate 1 is detected in the detection coil 33. The magnetic flux detected by the detection coil 33 is
After being appropriately amplified by the amplifier circuit 34, it is input to the comparison circuit 35. The threshold value generated by the threshold value generation circuit 36 is also input to the comparison circuit 35, and whether or not the magnetic flux detected by the detection coil 33 is equal to or higher than a predetermined strength, that is, one metal plate 1 is used. It is determined whether the magnetic flux has the strength when passing through the metal plate 1 or the magnetic flux having the strength when passing through two (or more) metal plates 1, and the suction plate 2 uses one metal plate 1 It is discriminated whether or not it has been lifted only or two or more sheets have been lifted. This determination result is input to a metal plate supply device equipped with a suction cup 2 to control the movement of the suction cup 2 so that the metal plate 1 is supplied to the line only when the suction cup 2 lifts only one metal plate 1. By controlling, it is possible to avoid the supply of the two-layer metal plate to the line.

[0004]

FIG. 3 is a schematic diagram showing the distribution of measured values of magnetic flux obtained by the detection coil of the two-metal-plate superposition detecting device shown in FIG. The distribution A of the measured values of the magnetic flux transmitted through only one metal plate and the distribution B of the measured values of the magnetic flux transmitted through the two stacked metal plates are separated from each other, and a threshold value is set in the middle of them.

However, if the measurement is continued in that state and the environmental temperature changes during that time, the distributions A and B change like the distributions A'and B'indicated by the one-dot chain lines in the figure, and two sheets are stacked. The hem of the distribution B ′, which is the distribution of the measured values of the metal plates, may exceed the threshold value and enter the side where it is determined that the metal plates are one metal plate. If it is determined and supplied to the line, a large load is applied to the working die as described above, the working die is damaged, and there is a possibility that great damage such as line stop or reworking of the working die occurs.

For example, when it is expected that the measured value fluctuates due to temperature, a thermometer may be provided and the threshold value may be changed according to the temperature measured by the thermometer.
However, the variation of the measured value due to the temperature varies depending on the material and thickness of the metal plate, which is a measure for measurement, and it is not possible to store the change function of the threshold value with respect to temperature for metal plates of various materials and thicknesses. However, there is a problem that it becomes a large and costly device.

In view of the above circumstances, the present invention has the following advantages even if there are factors that cause fluctuations in measured values, such as environmental temperature.
For example, it is an object of the present invention to provide a discriminating device that can always discriminate with high accuracy without performing a large-scale operation such as measuring temperature (variation factor) and feeding it back as described above.

[0008]

Means for Solving the Problems A discrimination device of the present invention which achieves the above object is: (1) A predetermined physical quantity of a measured object is sequentially measured for a plurality of measured objects, and each of the predetermined physical quantities is measured. A sensor for obtaining a measured value for each measured object (2) A comparator for comparing the measured value with a threshold value and discriminating the measured object into a plurality of groups depending on whether or not the measured value exceeds the threshold value (3) Of the plurality of measured objects that have already been measured, the plurality of measured objects that are distributed to at least one of the plurality of groups and that trace back in the order of measurement from the latest measured object It is characterized by further comprising threshold adjusting means for adjusting the threshold based on the measured value.

The application of the discriminating apparatus of the present invention is not limited, and the sensor is variously selected according to the application. The discriminating apparatus of the present invention is, for example, the sensor described above. However, it may be a magnetic sensor for measuring the thickness of a metal plate, and the comparator may discriminate whether or not a plurality of metal plates within a predetermined thickness standard are overlapped.

[0010]

The discriminating device of the present invention is the threshold value adjusting means of the above (3), that is, the object to be measured most recently among the objects to be measured which are distributed to at least one predetermined group. Since it is equipped with a means for adjusting the threshold value based on the measured values of a plurality of DUTs traced in the order of measurement from,
If the measured value shifts entirely during measurement, for example due to a change in the ambient temperature, the threshold value is adjusted by an amount corresponding to the shift. Thus, according to the discriminating apparatus of the present invention, the threshold value is adjusted without measuring the variation factor of the measured value such as the environmental temperature, and the discrimination of the measured object is always stable even if there is the variation factor of the measured value. Is done.

[0011]

Embodiments of the present invention will be described below. Here, an example of detection of overlapping two metal plates, which has also been described as a conventional technique, will be described. FIG. 1 is a block diagram of an embodiment of the discrimination device of the present invention. Elements corresponding to those in the conventional block diagram shown in FIG. 2 are designated by the same reference numerals as those in FIG. 2, and the differences will be described.

The magnetic flux transmitted through the metal plate (not shown) is detected by the detection coil 33, amplified by the amplification circuit 34, and input to the comparison circuit 35 and the A / D converter 41. In the A / D converter 41, the analog signal representing the measured value of the magnetic flux output from the amplifier circuit 34 is converted into a digital signal, and the measured value converted into the digital signal is stored in the memory 42. In this memo, the latest measured value X _n (n is
Represents the number of measurements from the start of measurement), 16 measurement values X _n , X sequentially traced back from the measurement value X _{n in the} order of measurement.
_n-1 , ..., X _n-15 are stored, and a new measurement value X is stored.
When storing _{n + 1} , the oldest measured value X _n-15 is erased. 16 measured values X _n stored in the memory 42,
X _n−1 , ..., X _n−15 are read by the average calculation unit 43, and the average calculation unit 43 calculates the average value x of these 16 measurement values x =
( _Xn + _xn-1 , ..., _Xn-15 ) / 16 is calculated. However, if the 16 measured values include the measured value when the comparison circuit 35 determines that the two sheets are stacked, the measured value is excluded from the calculation of the average value, The average value of only the measured values determined to be one metal sheet is obtained. The calculated average value is input to the threshold value generator 44. In this threshold value generator, the threshold value (see FIG. 3) is adjusted based on the input average value. The adjusted threshold value is converted into an analog signal by the D / A converter 45 and input to the comparison circuit 35.

When using the discriminating apparatus 30 shown in FIG. 1, the drive coil 31 is used at the beginning of the morning of the line working day.
Between the detection coil 33 and the detection coil 33, only one metal plate sample, which is to be supplied to the line, and two metal plate samples are stacked. Then, a threshold value is obtained from the output of the detection coil 33 at that time, and is set in the threshold value generation means 44 as an initial value of the threshold value. This is because the measured value changes depending on the type, thickness, etc. of the metal plate to be discriminated, as well as the environmental temperature, etc., as described above. This is because it is necessary to set a threshold value for the metal plate to be used and under the current environmental temperature. After setting the initial value of the threshold value in this way, the threshold value is sequentially adjusted according to the fluctuation of the measured value.

In the above embodiment, the average value of only the measured values determined to be one metal plate is obtained.
The threshold value may be adjusted by obtaining the average value (when the appearance frequency is high) of only the measured values determined to be two metal plates, and further, the average value of the measured values when one sheet is used. The threshold value may be adjusted based on both the average value of the measured values of two sheets. Further, in the above-described embodiment, the arithmetic mean of 16 measured values is obtained, but a weighted average in which the latest measured value is weighted may be used. The number of measured values for obtaining this average is not limited to 16 as a matter of course. Also, the threshold value cannot be adjusted only based on the average value of the measured values, and instead of the average value, the average value of the measured values such as the median value, (maximum value + minimum value) / 2, etc. , The threshold value may be adjusted based on the average value, and instead of the average value and the average value,
Alternatively, the threshold value may be adjusted in consideration of the variation (dispersion, etc.) of the measured values.

Further, although the above-mentioned embodiment is an example of detecting the two-ply metal plate, the use of the discriminating apparatus of the present invention is not limited to the detection of the two-ply metal plate, and for example, a predetermined value is used. The discriminating apparatus of the present invention has a wide range of applications, such as in the case where the materials and products of (1) are sorted into a plurality according to the size, weight, etc.

[0016]

As described above, according to the discriminating apparatus of the present invention, the object to be measured can be discriminated into a plurality of groups with high accuracy without measuring and feeding back the fluctuation factors of the measured value such as the environmental temperature. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a discrimination device of the present invention.

FIG. 2 is a schematic view showing an example of a two-metal-plate overlapping detection device.

FIG. 3 is a schematic diagram showing a distribution of measured values of magnetic flux obtained by a detection coil of the two-metal plate overlapping detection device shown in FIG.

[Explanation of symbols]

 30 Discrimination Device 31 Drive Coil 33 Detection Coil 35 Comparison Circuit 42 Memory 43 Averaging Unit 44 Threshold Generation Unit

Claims (2)

[Claims] 1. A sensor for sequentially measuring a predetermined physical quantity of a measured object for a plurality of measured objects to obtain a measured value of the predetermined physical quantity for each measured object, and a threshold value for the measured value. A comparator for discriminating the measured object into a plurality of groups depending on whether or not the measured value exceeds the threshold value, and among the plurality of measured objects which have already been measured, Threshold value adjusting means for adjusting the threshold value based on the measured values of a plurality of measured objects which are distributed to at least one of the groups and which are traced back in order of measurement from the measured object which is the latest measurement object; A discriminating device comprising: 2. The sensor is a magnetic sensor for measuring the thickness of a metal plate, and the comparator discriminates whether or not a plurality of metal plates within a predetermined thickness standard are overlapped. The discriminating device according to claim 1, wherein the discriminating device is present.