JPH06347561A - Metal classification device - Google Patents

Abstract

PURPOSE:To judge the presence and type of metal by detecting the pattern of a voltage difference induced in both coils when two coils consisting of a plurality of twisted wires are connected differentially and then a metal sample is inserted into the coils. CONSTITUTION:Coils 6 and 7 using a twisted wire consisting of two conductors are provided on a bobbin 22 with a spacing L. Edges 9a and 11a of conductors 9 and 11 of the coils 6 and 7 are connected, similarly other edges 9b and 11a are connected, and then excitation is performed by an AC signal source 4. Also, edges 8b and 10b of the conductors 8 and 10 of the coils 6 and 7 are connected and other edges 8a and 10a are connected to the input terminals of a differential amplifier 16. When a metal sample 5 is inserted into the coils 6 and 7, a difference is generated in the voltage induced at the conductors 8 and 10, current corresponding to the voltage difference flows to the conductors 8 and 10, the voltage difference is detected by the amplifier 16, and then a specific voltage value is output by a rectifier 18. Therefore, the type of the sample 5 can be discriminated by discriminating the output pattern of the rectifier 18 using a detection circuit 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a metal or a device for determining the kind of a detected metal.

[0002]

2. Description of the Related Art As an example of a metal detection device proposed in the past, there is a device shown in FIG. An AC signal source 34 is connected to the exciting coil 31 to excite the coil 31 and
A differential coil 36, which is composed of two detection coils 32 and 33 coaxially with the coil 31, and whose output ends are differentially connected, is arranged. The output end of the differential coil 36 is connected to a detection circuit 35. Connecting.

When the iron detection object 37 is inserted on the central axis of each coil of the metal detecting apparatus constructed as described above, the magnetic balance of the differential coil 36 is lost, so that the detection circuit 35 receives the AC The voltage of the frequency component is detected, and the ferromagnetic substance can be detected. However, when the balance of the windings of the detection coils 32 and 33 is poor, the output of the detection circuit 35 is generated and any metal is generated even though the object to be detected is not inserted on the shaft. It was not possible to determine if it was inserted in the metal detector.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the conventional metal detecting apparatus as described above, and provides a metal classifying apparatus capable of determining the presence and the type of a metal as an object to be detected. The purpose is to do.

[0005]

SUMMARY OF THE INVENTION In order to achieve this object, a metal sorting device according to the present invention comprises a first and a second wire wound with two twisted wires.
Deploy at a predetermined distance coaxially with the two coils of
One winding of each of the twisted wires of the first and second coils is connected in parallel or in parallel and excited by an AC signal source having a frequency f1, and each of the twisted wires of the first and second coils is connected. A means for detecting the magnitude of the component of the frequency f1 in the output voltage obtained by differentially connecting the other winding is provided,
When the metal sample to be detected is passed from the first coil to the second coil, the magnitude of the component of the frequency f1 is maximum when passing through the first coil and minimum when passing through the second coil. It is characterized in that the metal sample is classified by including a circuit for determining whether the maximum value is reached when passing through the first coil and the maximum value when passing through the second coil.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a diagram showing an embodiment of a metal sorting apparatus according to the present invention. In the figure, 6 is a first coil and 7 is a second coil, and both coils 6 and 7 are provided on the bobbin 22 with a predetermined space L therebetween. Each of the first coil 6 and the second coil 7 uses a stranded wire composed of at least two conductors, and connects one end 9a of the conductor 9 of the first coil and one end 11a of the conductor 11 of the second coil, Similarly, one end 9b of the conducting wire 9 of the first coil 6 and one end 11b of the conducting wire 11 of the second coil are connected, and this is excited by the AC signal source 4 having a frequency f1 (for example, 10 kHz).

On the other hand, one end 8b of the conducting wire 8 of the first coil and one end 10b of the conducting wire 10 of the second coil are connected, and the other ends 8a and 10a of the conducting wires 8 and 10 are respectively connected to the amplifier 16.
Connect to the input end of. That is, the coils formed by the conductors 8 and 10 are differentially connected. The output of the amplifier 16 is supplied to a detection circuit 19 via a filter 17 and a rectifier 18, and from the detection circuit 19, signals A and B for discriminating the metal species inserted in the bobbin are output terminals 20 and 21.
Will be output.

FIG. 2 is a schematic diagram for facilitating the understanding of the connection relation of each coil of the metal sorting apparatus shown in FIG. 1, in which the coil constituted by the conductive wires 9 and 11 is the primary side winding of the transformer. The coil constituted by the conductors 8 and 10 corresponds to the secondary winding of the transformer. The operation of the metal sorting device configured as described above will be described with reference to FIGS. 1 and 2. When the metal sample is not inserted in the metal classifier, the magnetic fields generated in the coils constituted by the conductors 9 and 11 are the same, and the voltage induced in the conductors 8 and 10 corresponding to the secondary winding of the transformer is Since the values are the same, no current flows between the terminals 8a and 10a of the differentially connected conductors 8 and 10, that is, no voltage difference is generated and no signal is generated from the differential amplifier 16.

On the other hand, when the metal sample 5 to be inspected is inserted on the central axes of the first coil 6 and the second coil 7 and the metal sample 5 exists in the first coil 6, the metal sample 5 is Two
As shown by the broken line in FIG. 5, the coil is inserted in the coil constituted by the conductors 8 and 9. Generally, when a ferromagnetic material such as iron or ferrite is inserted into the coil, the inductance of the coil increases. Conversely, when a non-ferromagnetic metal such as aluminum or brass is inserted into the coil, eddy current is generated and the coil inductance increases. Is known to decrease.

Therefore, the metal sample 5 made of a ferromagnetic material
Is inserted into the first coil 6, the inductance of the coil constituted by the conductor wire 8 increases and the voltage induced in the conductor wire 8 decreases, while the inductance of the coil constituted by the conductor wire 11 does not fluctuate. The voltage value induced in the circuit does not change. As a result, the balance of the voltages induced in the conductors 8 and 10 is lost, so that a current corresponding to the voltage difference is applied to the conductors 8.
And 10 and the differential amplifier 16 detects the voltage difference,
A predetermined voltage value is output from the filter 17 and the rectifier 18.

On the other hand, the second metal sample 5 made of a ferromagnetic material is used.
When it is inserted into the coil 7, the voltage induced in the conductive wire 10 decreases, and as described above, the current and voltage opposite to those when the metal sample 5 is inserted into the first coil are generated, resulting in the differential amplifier. 16 is detected. FIG. 3A is a diagram showing the output of the rectifier 18 depending on the position of the metal sample 5 when the ferromagnetic metal sample 5 is inserted into the metal sorting apparatus according to the present invention. When the metal sample 5 exists in the first coil 6 or the second coil 7, the rectifier output shows the maximum value or the minimum value, and when the metal sample 5 exists at the midpoint between the first coil and the second coil, the metal sample The output of the rectifier 18 becomes 0 because 5 has no effect on the first coil and the second coil, or the effect is canceled.

When a non-ferromagnetic material such as aluminum is inserted into the metal classifying device as the metal sample, if the metal sample 5 is present on the first coil 6 side, the inductance of the coil constituted by the conductive wire 9 is lowered, As a result, conductor 8
The voltage value induced in the coil constituted by the above increases.
On the other hand, since the inductance of the lead wire 11 that constitutes the second coil 7 does not change, a voltage difference occurs between the lead wires 8 and 10, and the rectifier 18 causes the detection circuit 1 to pass through the differential amplifier 16.
A signal is supplied to 9.

FIG. 3 (b) is a diagram showing the output of the rectifier 18 according to the position of the metal sample 5 when a metal material such as aluminum or brass is inserted into the metal sorting apparatus according to the present invention. Since the effect of the inserted metal sample on the coil is opposite to that of the case shown in (a), the rectifier 1
Although the 8 outputs have positive and negative inversions, the rectifier 18 output has the maximum or minimum value when the metal sample 5 coincides with the position of the first or second coil as in the case where the ferromagnetic material is inserted into the metal sorting device. Indicates a value. Therefore, the detection circuit 19
The type of the inserted metal sample can be recognized by discriminating the pattern of the output of the rectifier 18 using. Although various methods can be considered as the determination means in the detection circuit 19, as an example, the output of the rectifier circuit 18 is A / D converted and stored in a memory, and the maximum value and the minimum value are moved by a microprocessor or the like to move the metal sample. As a result, it is possible to use the one that is recognized by determining at which position it occurs.

That is, when the detection circuit 19 detects the pattern of FIG. 3A, a signal indicating that the inserted metal sample is a ferromagnetic material is output from the output terminal 20,
Further, when the pattern of FIG. 3B is detected, a signal indicating that the inserted metal sample is not a ferromagnetic material may be output from the output end 21. Therefore, when the pattern as shown in (a) or (b) cannot be obtained, it is determined that the inserted sample is not a metal, and the fact is output from an output end (not shown) or the output ends 20 and 21 are not shown. It is also possible to determine whether or not the object to be inspected is a metal by setting such that neither of them outputs.

In the above description, the windings forming the first and second coils have been described by using the twisted wire made of two conductors, but the present invention is not limited to this and, for example, four twisted wires. May be used to form the first coil and the second coil, and two of the four conductors may be bundled and used.
It is clear that the diameter of the coil may be determined from the size and resolution of the sample. Further, in the present embodiment, the conductive wires 8 and 1
However, the present invention is not limited to this, and one end 11b of the conductive wire 11 and one end 9a of the conductive wire 9 are connected to each other, and the other ends 9b and 11 of the conductive wires 9 and 11 are connected.
A similar function can be obtained by using a summon connection for connecting a signal source between a and a.

[0016]

Since the present invention is constructed and functions as described above, it has a remarkable effect in enabling detection and classification of metals with a very simple device.

[0017]

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a metal classification device according to the present invention.

FIG. 2 is a schematic diagram for facilitating understanding of a connection relationship of each coil of the metal classification device shown in FIG.

FIG. 3A is a diagram showing the output of the rectifier 18 depending on the position of the metal sample 5 when the ferromagnetic metal sample 5 is inserted into the metal sorting apparatus according to the present invention. (B) A diagram showing the output of the rectifier 18 according to the position of the metal sample 5 when a metal material such as aluminum or brass is inserted into the metal sorting apparatus according to the present invention.

FIG. 4 is a diagram showing an example of a metal detection device that has been conventionally proposed.

[Explanation of symbols]

4 ... AC signal source, 5 ... metal sample, 6 ...
First coil, 7 Second coil, 8, 9, 1
0, 11 ... Lead wire, 16 ... Differential amplifier, 17
‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaido Kan 1-1, Kotani, Samukawa-cho, Takaza-gun, Kanagawa Toyo Communication Equipment Co., Ltd.

Claims (2)

[Claims] 1. A stranded wire of the first and second coils, which is arranged coaxially with a first and a second coil wound with two stranded wires at a predetermined distance. Outputs obtained by connecting one winding in parallel or in parallel and exciting it with an AC signal source having a frequency f1 and differentially connecting the other windings of the stranded wires of the first and second coils. A means for detecting the magnitude of the component of the frequency f1 in the voltage is provided, and when the metal sample to be detected is passed from the first coil to the second coil, the magnitude of the component of the frequency f1 is the first coil. Circuit for determining whether it is maximum when passing through the second coil, is minimum when passing through the second coil, is minimum when passing through the first coil, and is maximum when passing through the second coil A metal classifying device for classifying the metal sample according to the above. 2. The two twisted wires are replaced with two or more twisted wires, and the one and the other windings are selected from the two or more twisted wires or divided into two systems for use. The metal classification device according to claim 1, wherein