JPH10111362A - Metal detection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the malfunction of a metal detector and detect the most minute metal piece by detecting presence or absence of a mixed metal by a metal detector after electrically neutralizing with ions of an ion generator the static electricity which an inspected body is charged with. SOLUTION: A metal detector 12 is disposed in a carrying path of a carrying belt 11 that carries a specimen 10, and a discharge type ion generator 20 is disposed on an upstream side of the metal detector 12. The discharge type ion generator 20 is connected to a high-voltage generator 21, an air passing between high-voltage positive and negative electrodes 22 and 23 is ionized, and this ion blows the specimen 10 and electrically neutralizes static electricity. An ion generation state is sensed by an ion sensing sensor 24, and an optimal ion generation is made possible by feeding back the result to positive and negative electrodes 22 and 23 via the high-voltage generator 21. Consequently, static electricity generated by mutual friction of the specimen 10 or friction between a carrying belt 11 and a roller 13 is neutralized by ion and erased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a metal detection method and a metal detection device in the production of foods such as confectionery, the production of pharmaceuticals, the loading and transporting of synthetic resin pellets.

[0002]

2. Description of the Related Art Conventionally, for example, as shown in FIG. 4, a metal detector 12 is arranged in a transport path of a transport belt 11 for transporting an object 10 to be inspected.
There is a metal detection device that detects a metal mixed in a metal. However, the inspected object 10 to be transported is, for example, the transport belt 1
The static electricity generated by the friction between the roller 1 and the roller 13 is easily charged, and the metal detector 12 easily malfunctions. Therefore, a conductive plastic frame is used to prevent electrostatic charging (Japanese Utility Model Application Laid-Open No. 55-116280), or static electricity is discharged by a conductive roller (Japanese Utility Model Application Publication No.
18716) and a method of grounding with an electrostatic brush has been proposed.

[0003]

However, in the above-described method, the charging of the device under test 10 cannot be completely prevented. If the device 10 is used for a long time, static electricity accumulates and the metal detector 12 malfunctions due to static noise. Was inevitable. For this reason, the detection sensitivity could not be increased, and a minute metal piece could not be detected. Furthermore, even if the detection sensitivity is lowered, the metal detector 1 is not affected by electrostatic spark noise reaching tens of thousands of volts.
2 has a problem that a malfunction occurs.

[0004] In view of the above problems, an object of the present invention is to provide a metal detection method and a metal detection device which can detect a small metal piece without causing a malfunction of the metal detector.

[0005]

In order to achieve the above object, a metal detection method according to the present invention comprises: neutralizing static electricity charged on a test object with ions of an ion generator;
This is a step in which the presence or absence of metal mixed into the inspection object is detected by a metal detector.

[0006] In addition, a step of electrically neutralizing static electricity charged on the moving test object with ions of an ion generator, and then detecting the presence or absence of metal mixed in the test object with a metal detector. Is also good.

Further, the metal detecting device according to the present invention comprises:
In a metal detection device in which a metal detector is arranged on a transport path of an object to be inspected, a configuration in which an ion generator is arranged around the same position as the metal detector or on the upstream side of the transport path for transporting the inspected object. May be done.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment according to the present invention will be described with reference to FIGS. As shown in FIG. 1, the metal detector according to the first embodiment arranges a metal detector 12 in a transport path of a transport belt 11 that transports an object to be inspected 10 and an upstream side of the metal detector 12. The discharge type ion generator 20 is arranged.

The inspection object 10 is not limited to a board material of a building material, but is used for food, medicine, medicine,
It may be a synthetic resin or the like.

The metal detector 12 can be selected from existing ones. For example, the metal detector 12 is placed in a magnetic field generated in a transport path.
A method of detecting the presence or absence of metal mixed into the device under test 10 by detecting a change in the magnetic field when the light passes therethrough.

The discharge type ion generator 20 is connected to a high voltage generator 21 and, for example, after ionizing air passing between the high voltage positive and negative electrodes 22 and 23 as shown in FIG. These ions are sprayed on the test object 10 to electrically neutralize static electricity. The ion generator 20 detects an ion generation state with an ion sensor 24 and feeds back the result to the positive and negative electrodes 22 and 23 via a high voltage generator 21 to enable optimal ion generation. ing.

Therefore, even if static electricity generated by friction between the test objects 10 or friction between the transport belt 11 and the rollers 13 is charged on the test object 10, the transport belt 11, and the metal detector 12, the aforementioned The ions in the ion generator 20 electrically neutralize the static electricity and erase it, thereby preventing malfunction due to electrostatic spark noise. For this reason, the metal detector 1
2 has the advantage that the detection sensitivity can be increased and a minute metal can be detected.

In the second embodiment, as shown in FIG. 2, the first embodiment is a case in which air is ionized by the discharge ion generator 20 and static electricity is electrically neutralized by the obtained ions. On the other hand, there is a case where gas molecules are ionized by soft X-rays irradiated by the soft X-ray generator 25, and static electricity is neutralized and erased by the obtained ions. The rest is almost the same as the above-described first embodiment, and the description is omitted.

According to this embodiment, static elimination is performed instantaneously. Further, since substantially the same amount of ions of both positive and negative polarities are generated, there is no reverse charging, and complete static elimination is performed. Furthermore, there is no generation of ozone. In addition, since there is no generation of ions due to discharge, there is no generation of induced voltage or induced voltage. In addition, there is an advantage that static elimination of an object moving at high speed is also possible.

In the above-described embodiment, a case has been described in which an ion generator or the like is disposed upstream of the metal detector to electrically neutralize static electricity. Perimeter, for example, side or directly above, or
It may be arranged downstream of the metal detector. When the amount of generated static electricity is large, a plurality of ion generators may be installed in the width direction and the longitudinal direction, or different types of ion generators may be used in combination. Furthermore, in the above-described embodiment, the case where the test object is moved by the transport belt has been described. However, the present invention is not limited to this. For example, the test object moves in the cylinder by using a natural fall or air pressure. It may be applied in the case. Further, the present invention may be applied to a case where the inspection object is moved for each of a plurality of connected buckets and inspection is performed. In the above-described embodiment, the case where static electricity of the moving inspection object is erased has been described. However, the present invention may be applied to a batch-type manufacturing process in which static electricity is erased for each lot.

[0016]

【Example】

(Example 1) In the metal detection device shown in FIG.
The ion generator 20 was disposed right above the metal detector 12 through which the conveyor belt 11 of the conveyor passed, and whether or not the metal detector 12 malfunctioned depending on whether or not ions were generated was measured.

Note that a discharge type ion generator was used as the ion generator. The distance from the ion generator to the metal detector was 135 mm, and the distance from the ion generator to the surface of the conveyor belt was 300 mm.

From the measurement results, it was found that the noise level when no ions were generated was 0.20 to 0.40 volts, whereas the noise level when ions were generated was 0.20 to 0.35. It was a bolt. From this measurement result, it was found that the generated ions did not adversely affect the metal detector 12.

(Example 2) An iron ball alone or an object to which an iron ball was mixed was transported by the transport belt of the metal detection device, and the minimum diameter of the iron ball that could be detected by the metal detector was measured. The measurement results are shown in FIG.

In FIG. 3B, the ground is made by bringing a silver brush into contact with the transport roll and the transport belt, and the silver brush is brought into contact with the first roll.
The test was performed by connecting to the seed or special three kinds of measurement grounds.
Further, MDF means a material deposited in a mat shape before pressing a medium-density fiberboard, and flour was used for food and polyester was used for fiber.

As is evident from the measurement results, it was found that the ion method had better metal detection ability than the case of grounding as well as the case of not grounding. In addition, in the ion system, not only the problem of sensitivity but also the rare occurrence of electrostatic spark noise could be prevented.

[0022]

As is apparent from the above description, according to the first aspect of the present invention, the ions of the ion generator electrically neutralize the static electricity charged on the test object and erase it. Erroneous operation due to electrostatic noise is eliminated. For this reason, the detection sensitivity can be increased, and a finer metal piece can be detected than in the conventional example. In particular, by neutralizing and erasing not only the static electricity charged to the object to be inspected by the ions of the ion generator but also the static electricity charged to the metal detector and the conveyor belt, malfunctions can be further prevented while preventing malfunction. Fine metals can be detected.
According to the second aspect, since the moving inspection object can be continuously inspected, a metal detection method with high productivity can be obtained. According to the third aspect, since the ion generator is disposed around the same position as the metal detector or on the upstream side, static electricity charged on the test object located on the upstream side is electrically neutralized and erased. .
For this reason, it is possible to prevent a malfunction of the metal detector, and it is possible to detect a finer metal piece by further increasing the detection sensitivity.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a metal detection device according to the present invention, wherein FIG. 1 (a) is a front view and FIG. 1 (b) is a principle diagram showing elimination of static electricity by an ion generator.

FIG. 2 shows a second embodiment of the metal detection device according to the present invention, wherein FIG. 2 (a) is a front view and FIG. 2 (b) is a principle diagram showing removal of static electricity by an ion generator.

FIG. 3A is a front view showing a metal detector used in Examples 1 and 2 of the present invention, and FIG. 3B is a graph showing measurement results.

FIG. 4 is a front view of a metal detection device according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Inspection object, 11 ... Conveying belt, 12 ... Metal detector, 13 ... Roller, 20 ... Discharge type ion generator, 21 ...
High voltage generator, 25 ... Soft X-ray generator.

Claims (3)

[Claims] 2. A method according to claim 1, further comprising the step of electrically neutralizing static electricity charged on the test object with ions of an ion generator, and then detecting presence / absence of metal mixed into the test object with a metal detector. Detection method. 2. The method according to claim 1, wherein the static electricity charged on the moving test object is electrically neutralized by ions of an ion generator, and then the presence or absence of metal mixed into the test object is detected by a metal detector. Metal detection method. 3. A metal detector in which a metal detector is arranged on a transport path of an object to be inspected, wherein an ion generator is provided around or at the same position as the metal detector in the transport path for transporting the object to be inspected. A metal detection device, comprising: