JPH1130672A - Metal detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably detect metallic foreign matters particularly in a long-shaped object by providing adjusting means (guides) for adjusting the direction of the inspection object in a conveying direction. SOLUTION: A metal detecting device 200 is provided with a conveyor 2 serving as an inspection object conveying means, and guides 3 for adjusting the direction of an inspection object. The guides 3 are held to both ends of the conveyor 2 and provided in front of a metal detecting part 1. The guides 3 are of such shape that the distance between both ends is narrowed toward the metal detecting part 1 and that the distance between both ends of the guides 3 almost coincides with the width of the inspection object in a part close to the metal detecting part 1. The metal detecting part 1 has a transmitting coil generating the magnetic field, and a receiving coil detecting the magnetic field generated by the transmitting coil, and detects metallic foreign matters included in the inspected object on the basis of the change of the magnetic field at the time of arranging the inspection object in the magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal detecting device for detecting a metal, for example, a metal detecting device for detecting a metallic foreign substance contained in an inspection object.

[0002]

2. Description of the Related Art Conventionally, for example, in a process of manufacturing food or the like, a metal detection device for detecting a metal foreign material (hereinafter, referred to as a metal foreign material) contained in food as an inspection object has been widely used.

Here, a method of detecting a metal foreign matter by a metal detection device will be briefly described. The metal detection device generally includes one transmission coil and two reception coils, and generates an alternating magnetic field by passing a sinusoidal current through the transmission coil. Further, the two receiving coils are arranged such that the alternating magnetic field generated by the transmitting coil crosses the respective receiving coils in the same manner. In such a situation, when the test object mixed with the metallic foreign matter passes through the alternating magnetic field, the state of the magnetic field changes, so that the voltage induced in the two receiving coils is lost and the output signal is lost. Occurs. Therefore, the presence or absence of a metallic foreign substance is detected based on the change in the output signal.

However, when a metal is used as a packaging material for the object to be inspected, the output signal changes only by passing the packaging material through the above-described metal detection device. In addition, even if the packaging material does not include metal, the output signal changes when the content of the inspection object has conductivity due to the presence of moisture, salt, or the like. Originally, such a metal detection device is a device for detecting metal foreign matter mixed in contents such as foods that require safety. Therefore, in practice, the metal foreign matter is contained in the inspection object (content). Even if is not mixed, even if the output signal is slightly changed due to the state of the contents, it is determined that the metal foreign matter is mixed in the inspection object. Therefore, when the inspection object is passed through the metal detection device, it is necessary to minimize the change in the magnetic field caused by the state of the contents of the inspection object.

FIG. 1 is a diagram showing the influence of an inspection object placed in a magnetic field. As shown in these figures, the state of the magnetic field changes according to the area of the inspection object that blocks the magnetic field. That is, the larger the area of the inspection object that blocks the magnetic field, the greater the influence of the change in the magnetic field caused by the inspection object.

FIGS. 2 and 3 are diagrams showing the arrangement of the transmitting and receiving coils of the metal detecting unit and the direction of the magnetic field in a general metal detecting device. In FIG. 2, the transmission coil 51 and the two reception coils 52 are arranged on the same axis of the coils so as to sandwich the transmission coil 51 between the two reception coils 52, and from right to left in FIG. A magnetic field is generated. In addition, in FIG. 3, when two receiving coils 54 are arranged to face each other below the transmitting coil 53, FIG.
A magnetic field is generated from above to below. In such a case, for example, with respect to the inspection object having a long shape such as the inspection object 50, the inspection object is moved in the longitudinal direction (the direction of the arrow indicating the transport direction in FIGS. 2 and 3). If so, the adverse effect of the inspection object (content) at the time of detection is minimized.

[0007]

However, in the actual manufacturing (inspection) process, the test object 50 having a long shape as shown in FIGS. 2 and 3 is stably transported in the longitudinal direction. Metal detector 11 of metal detector 100
It does not always pass through the predetermined area of 0, and may be conveyed in a state (posture) as shown in FIG. In such a case, the area of blocking the magnetic field (not shown) generated in the metal inspection unit 110 increases depending on the state of the arrangement of the inspection object 50, and the detection accuracy decreases due to a change in the output signal. Becomes

[0008] As shown in FIG.
However, even when it is conveyed by the conveyor 200 in the longitudinal direction, the passing position in the metal detection unit 110 of the metal detection device 100 may not be stable.
Also in such a case, there is a problem that the position of the coil and the object to be inspected changes and the output signal changes, thereby lowering the detection accuracy.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a metal detector capable of detecting the presence or absence of a metal foreign substance in an object with high sensitivity. An object of the present invention is to provide a metal detection device capable of detection.

[0010]

In order to achieve the above-mentioned object, a metal detector according to the present invention has the following configuration.

In other words, the present invention is a metal detecting device provided with detecting means for detecting a metallic foreign matter mixed in an object to be inspected while the inspecting object is being conveyed by the conveying means. The inspection object is passed by the adjustment means for adjusting the conveyance direction of the means in a posture in which the conveyance direction of the conveyance means and the longitudinal direction of the inspection object are substantially parallel to the detection means provided downstream. Characterized by

Preferably, the adjusting means is a guide provided in front of the detecting means, and the guide is
It is preferable that the shape has a width that is substantially equal to the length of the inspection object in the lateral direction as approaching the detection means.

Further, for example, the detecting means includes a transmitting coil for generating a magnetic field, and a receiving coil for detecting a magnetic field generated by the transmitting coil, and a change in the magnetic field when an object is placed in the magnetic field. Based on the above, it is preferable to detect a metallic foreign substance included in the inspection object.

With these configurations, The presence / absence of a metallic foreign substance in a test object is detected with high sensitivity.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a metal detecting device according to the present invention will be described with reference to the drawings.

<First Embodiment> A first embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is a perspective view of a metal detecting device according to a first embodiment of the present invention. FIG. 7 is a top view of the metal detection device according to the first embodiment of the present invention. The metal detection device 200 is a device that detects a metal foreign substance mixed in an inspection object. As shown in FIGS. 6 and 7, the metal detection device 200 includes a transport conveyor 2 as a transport means of the inspection object and a guide 3 for adjusting the direction of the inspection object 4 transported by the conveyor. . Arrows indicate the transport direction of the transport conveyor 2. Guide 3
It is held at both ends of the conveyor 2 and is provided in front of the metal detector 1. The guide 3 has a shape in which the distance between both ends is reduced toward the metal detection unit 1, and the distance between both ends of the guide is substantially equal to the width of the inspection object 4 in a portion close to the metal detection unit 1. The inspection object 4 is an object to be inspected to check whether or not metal foreign matter is mixed.

FIG. 8 is a block diagram showing the configuration of the metal detection unit of the metal detection device according to the first embodiment of the present invention.

In FIG. 1, the metal detecting section 1 includes a detecting head 5 and a detecting circuit 6. The detection head 5 includes 1
It comprises one transmitting coil 7, two receiving coils 8, and an oscillating circuit 9. The transmission coil 7 is a coil through which a predetermined sine wave current flows, and the reception coil 8 is a coil that receives a signal oscillated from the transmission coil 7.
The oscillating circuit 9 generates the predetermined sine wave current and supplies it to the transmission coil 7. In the present embodiment, the inspection object 4 passes through the centers of the transmission coil 7 and the reception coil 8 inside the metal detection unit 1 by the conveyor 2.

As for the positional relationship between the transmitting coil 7 and the receiving coil 8, the receiving coil 8 sandwiches the transmitting coil 7,
Although a detection head having a configuration arranged coaxially is employed, it goes without saying that, for example, a detection head having a configuration in which the reception coil 8 is disposed below the transmission coil 7 may be used.

The detection circuit 6 includes an amplification circuit 10, a synchronous detection circuit 11, a filter circuit 12, and an analog / digital (A / D) conversion circuit 13. Amplifier circuit 10
Is a circuit for amplifying the signal from the receiving coil 8.
The synchronous detection circuit 11 is a circuit that extracts a signal when a foreign metal is mixed based on a signal from the amplification circuit 10. The filter circuit 12 is a circuit that removes noise included in the output signal of the synchronous detection circuit 11. The A / D conversion circuit 13 is a circuit that converts a signal from the filter circuit 12 into a digital signal. This digital signal is output to an alarm output circuit (not shown) or an arithmetic module (not shown) included in the metal detection device 200.

In the metal detecting device having the above-described configuration, the inspection object 4 is transported by the transportation conveyor 2 in a state where the transportation direction of the transportation conveyor 2 and the longitudinal direction of the inspection object 4 are not parallel. The output value output from the / D conversion circuit 13 was measured with and without the guide 3.

FIG. 9 is a diagram showing a measurement result according to the first embodiment of the present invention. In the figure, the horizontal axis plots the number of times the inspection object 4 is inspected, and the vertical axis plots the output value. As is clear from the results, when the guide 3 was provided, the output value was lower than when the guide 3 was not provided. That is, when the guide 3 is provided, the inspection object 4 is transported by the transport conveyor 2 and the metal detection unit 1 is moved.
This is because the direction is adjusted by the guide 3 as the distance from the object approaches, and the metal detection unit 1 can pass through the posture in which the transport direction shown in FIG. 2 and the longitudinal direction of the inspection object are substantially parallel. In other words, it indicates that the inspection object 4 passes through the metal detection unit 1 with the least influence on the magnetic field. Further, when the guide 3 is provided, the variation in the output value is reduced as compared with the case where the guide 3 is not provided. This indicates that the provision of the guide 3 allows the inspection object 4 to pass through the predetermined inspection area of the metal detection unit 1 as shown in FIG. 7, thereby achieving stable detection accuracy. .

<Second Embodiment> FIG. 10 is a perspective view of a metal detector according to a second embodiment of the present invention. The metal detection device 300 of the present embodiment is basically the same as that of the first embodiment, and only different parts will be described. The metal detection device 300 according to the present embodiment includes a roller guide 20 including a plurality of rollers instead of the above-described guide 3. As shown in the drawing, the roller guide 20 has the same installation state and overall shape as the guide 3, so that in addition to the effects obtained by the guide 3 described in the first embodiment, the following Has unique effects.

That is, the plurality of rollers of the roller guide 20 are rotated by a driving mechanism (not shown) such that the rollers on the near side in FIG. 10 rotate clockwise and the rollers on the rear side in FIG. 10 rotate counterclockwise. ing. Accordingly, even when the inspection object 4 is conveyed to the area of the roller guide 20 in a posture in which the conveyance direction of the conveyance conveyor 2 and the longitudinal direction of the inspection object 4 make a certain angle, the position of the inspection object 4 is Is adjusted, good detection is possible in the metal detection unit 1.

The drive control of the roller guide 20 is performed by an external device or by the detection circuit 6 of the metal detection unit 1 (in this case, a motor control circuit is added). Needless to say, it's good.

[0027]

As described above, according to the present invention,
A metal detection device that can detect the presence or absence of metal foreign matter in a test object with high sensitivity, and in particular, provides a metal detection device that can stably detect a metal foreign material in a long shape test object I do.

[0028]

[Brief description of the drawings]

FIG. 1 is a diagram showing the influence of an inspection object placed in a magnetic field.

FIG. 2 is a diagram illustrating an arrangement of transmission and reception coils of a metal detection unit and a direction of a magnetic field in a general metal detection device.

FIG. 3 is a diagram illustrating an arrangement of transmission and reception coils of a metal detection unit and a direction of a magnetic field in a general metal detection device.

FIG. 4 is a diagram showing an example of a positional relationship between an inspection object and a metal detection device.

FIG. 5 is a diagram illustrating an example of a positional relationship between an inspection object and a metal detection device.

FIG. 6 is a perspective view of the metal detection device according to the first embodiment of the present invention.

FIG. 7 is a top view of the metal detection device according to the first embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of a metal detection unit of the metal detection device according to the first embodiment of the present invention.

FIG. 9 is a diagram showing a measurement result as the first embodiment of the present invention.

FIG. 10 is a perspective view of a metal detection device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,110 Metal detection part 2,200 Conveyor 3 Guide 4,50 Inspection object 5 Detection head 6 Detection circuit 7,51,53 Transmission coil 8,52,54 Receiving coil 9 Oscillation circuit 10 Amplification circuit 11 Synchronous detection circuit 12 Filter circuit 13 A / D conversion circuit 20 Roller guide 100, 200, 300 Metal detector

Claims (6)

[Claims] 1. A metal detecting apparatus comprising: detecting means for detecting a metallic foreign substance mixed in a test object while the test object is being conveyed by a conveying means, wherein the direction of the test object is determined by the conveyance. The inspection object is passed by the adjustment means for adjusting the conveyance direction of the means in a posture in which the conveyance direction of the conveyance means and the longitudinal direction of the inspection object are substantially parallel to the detection means provided downstream. A metal detection device, characterized in that the detection is carried out. 2. The adjusting means is a guide provided in front of the detecting means. As the guide approaches the detecting means, the adjusting means has a width substantially equal to the length of the inspected object in the lateral direction. 2. A shape having a shape as follows.
The metal detection device according to any one of the preceding claims. 3. The metal detecting device according to claim 2, wherein the guide has a plurality of rollers along a shape thereof. 4. The detecting means includes a transmitting coil for generating a magnetic field, and a receiving coil for detecting a magnetic field generated by the transmitting coil, and detects a change in the magnetic field when an object is placed in the magnetic field. The metal detection device according to claim 1, wherein a metal foreign substance included in the inspection object is detected based on the detection result. 5. The metal detecting apparatus according to claim 4, wherein the adjusting unit adjusts a longitudinal direction of the inspection object to be substantially parallel to a magnetic field generated by the transmission coil. 6. The detecting means includes:
6. The apparatus according to claim 5, further comprising two receiving coils, wherein the transmitting coil is sandwiched between the two coils, and the centers of the respective coils are arranged on the same axis. Metal detector.