JP2018063229A - Metal foreign substance detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal foreign substance detector which can detect metal foreign substances in an inspection target object while removing the influence of disturbance of an external magnetic field, an electromagnetic wave, or a magnetic field, the inspection target object being made of a medical product, a cosmetic, or a food product, for example, filled in a packaging bag.SOLUTION: The metal foreign substances in an inspection target object 2 made of a packaged body filled in a packaging body are detected by a sensor 3 made of a sensor coil. The inspection target object 2 is conveyed by a roller conveyor 23 with an adjustable inclination angle and is inspected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a metal foreign object detection device that detects a metal foreign object mixed in an object to be inspected. In particular, the present invention relates to a metal foreign object detection device that detects a metal foreign object mixed in a test object filled in a non-magnetic packaging bag such as aluminum or an aluminum vapor-deposited film, or a non-metallic packaging bag such as a plastic resin film.

  Metal foreign object detection devices are used in various fields. A typical example is detection of metallic foreign matter mixed in a product in the product manufacturing process. Specifically, in the manufacturing process of foods, pharmaceuticals, etc., some containers such as transporters, washing machines, stirrers, cutting machines, kneaders, steamers etc., blades, sieves, etc. are worn, metal Due to fatigue and the like, fragments such as curl, fracture, peeling, shaving, and chipping may enter the product as foreign matter.

  It is important to detect these foreign substances and remove them from the product. An electromagnetic sensor coil or the like is used as means for detecting a magnetic metallic foreign matter mixed in an inspection object which is a product. The metal foreign matter is often austenitic stainless steel that constitutes the above-described various containers, blades, sieves, and the like. Austenitic stainless steel induces martensitic transformation when plastically deformed, and changes to a crystalline structure with weak magnetism.

  For this reason, a magnet booster is disposed in the vicinity of the sensor coil, and the metal foreign object is magnetized by the strong magnetic lines of force, so that the metal foreign object can be detected with high sensitivity. When the object to be inspected passes through the magnet booster, the magnetism generated by the magnet booster causes the magnetism of the metal foreign object to be magnetized in a certain direction. Patent Documents 1 and 2 propose metal foreign matter detection devices using this principle.

  The devices described in Patent Documents 1 and 2 detect metal foreign objects in an object to be inspected such as food, and succeeded in detecting a minute magnetic material that is a metal foreign object using the proposed sensor coil. . Specifically, Patent Document 1 discloses a metal foreign object detection method and a metal foreign object detection device that detect metal foreign objects mixed in an object to be inspected. According to this invention, not only metal foreign matter such as stainless steel mixed in the inspection object is detected, but also metal mixed in the inspection object such as food, medicine, industrial material wrapped in conductive packaging material. Foreign objects can also be detected.

The metal foreign object detection device described in Patent Document 1 generates a minute magnetic field by a detection unit having one coil with a configuration in which a conductor is wound around a core, and detects a magnetic field detected from a metal object in response to the minute magnetic field, The detection signal is output as a detection voltage or detection current of the coil.
The minute magnetic field is a voltage applied to the coil at a frequency of several hundred Hz to several tens of kHz, or a direct current, and a small amount of current is supplied, and the magnetization (BH) characteristic of the core constituting the coil is small. This utilizes a non-linear portion where the magnetic flux density (B) and the magnetic field (H) are very small values near zero.

  When a metallic foreign object passes near the coil, the formation of magnetic lines of force linked to the coil is disturbed, and the amplitude, phase, and frequency of the signal voltage change. Thereby, a metal foreign object is detected. This apparatus has an excellent sensitivity capable of detecting metallic foreign objects of 1 mm or less. It is also possible to detect an elongated metal object such as a needle in an aluminum package and an antioxidant made of metal powder.

  A metal detector disclosed in Patent Document 3 includes a conveyance path that conveys an object to be detected, a sensor coil that is provided in the middle of the conveyance path, and that has a coil wound around a core for generating a magnetic field by passing an electric current. The magnet is arranged in contact with the core. Specifically, an unequal static magnetic field is formed by the static magnetic field of the magnet and the alternating current of the sensor coil. When the object to be detected crosses this unequal magnetic field, the metal foreign object is temporarily magnetized, and at the same time, the magnetic field generated from the magnetized object to be detected disturbs the magnetic field linked to the sensor coil.

  The sensor coil sends out the disturbance of the magnetic field as a detection signal. Patent Document 4 discloses a metal foreign object detection device that detects a metal foreign object in a flowing packaging bag before an accumulator that temporarily accumulates the packaging bag. The metal foreign object detection device detects metal foreign objects using sensor coils disposed on both sides of the tubular guide through the packaging bag through an elongated hollow tubular guide.

International Publication WO2003 / 027659 JP 2005-188985 A JP 2004-85439 A Utility model registration No. 3177557

  However, many conventional detectors are devices for inspecting products conveyed by a belt conveyor or manually inspecting products by passing the vicinity of a sensor coil. There is a demand for a small metal foreign object detection device that can be used on a desktop so that it can be used in food processing sites that handle a large variety of rods on a small scale.

The present invention has been made based on the technical background as described above, and achieves the following objects.
An object of the present invention is to provide a small-sized metal foreign object detection device capable of detecting metal foreign objects contained in small-scale inspected articles such as various types of pharmaceuticals, cosmetics, and foodstuffs.

In order to achieve the above object, the present invention employs the following means.
The metal foreign object detection device of the invention 1 of the present invention is
A transport means for transporting the inspection object using gravity of the mass of the inspection object itself on an inclined surface which is a conveyance path;
In order to magnetize or reinforce the magnetic material in the inspection object, magnetizing means provided in the middle of the transport path;
Sensor means that is provided in the middle of the conveyance path and next to the magnetization means in the conveyance direction of the inspection object, and outputs a detection signal;
In the metal foreign object detection device comprising: a detection means including a signal processing unit that obtains the detection signal and performs signal processing to determine the presence or absence of the magnetic body and outputs an output signal indicating the determination result;
The conveyance path has angle adjusting means for adjusting the angle of the inclined surface.

The metal foreign matter detection device of the invention 2 of the present invention is the invention 1,
The sensor means is formed by winding a lead wire around a core, and uses a non-linear portion in which the magnetic flux density (B) and magnetic field (H) of the magnetization (BH) characteristic of the core are very small values near zero. It comprises a sensor coil that detects a change in the surrounding magnetic field and outputs the detection signal.

The metal foreign matter detection device of the invention 3 of the present invention is the invention 1 or 2,
The conveyance path is detachable from a housing forming a main body of the metal foreign object detection device.

The metal foreign matter detection device of invention 4 of the present invention is the invention 3,
The conveyance surface of the conveyance path is a detachable roller conveyor.

The metal foreign matter detection device of invention 5 of the present invention is the invention 3,
The conveyance surface of the conveyance path is a detachable flat plate or corrugated plate.

The metal foreign matter detection device of the invention 6 of the present invention is the invention 4 or 5,
The inclination angle of the transport surface is adjusted by an angle of 7 degrees, 10 degrees, 15 degrees, and 20 degrees.

  The detection principle of the detection unit described above is that a magnetic field is generated by applying a voltage or supplying a current to at least one sensor coil and responding to the magnetic field from a metallic foreign object in the inspection object. The detection magnetic field is detected as a detection voltage or a detection current of the sensor coil, and a detection signal is output. The detection signal is analyzed to identify the metal foreign object. The detection voltage or detection current of the sensor coil is a minute value and is easily affected by external magnetic field or magnetic field disturbance. Shield.

The minute magnetic field has a small voltage applied to the sensor coil or a supplied current, and among the magnetization (BH) characteristics of the core constituting the sensor coil, the magnetic flux density (B) representing the magnetization characteristic and the magnetic field ( H) uses a non-linear part having a minute value near 0, the current or voltage is a frequency of several hundred Hz to several tens kHz, or a direct current, and when a metallic foreign object passes near the sensor coil, A voltage and current flowing in the coil are induced. This can be said that the frequency of the sensor coil changes.
The minute magnetic field of the sensor coil is a known technique as shown in Patent Document 1 and the like, and details thereof are omitted.

  The inventors of the present invention have filed a patent application relating to “a metallic foreign object detection method and apparatus” (Patent Document 1). All or part of the contents of the present invention are also included in the present invention. In the metal foreign matter detection method of the present invention, in order to detect a metal foreign matter mixed in the process of manufacturing the inspection object in the package, a transport step of transporting the inspection object through a transport path, and in the middle of the transport path In a metal foreign object detection method comprising: a metal foreign object detection step for detecting a metal foreign object mixed in the object to be detected by generating a magnetic field by a detection unit having a coil having a configuration in which a conductive wire is wound around a core. , Applying a voltage to one coil or supplying a current to generate a minute magnetic field, and detect and detect a magnetic field detected from the metal foreign object in response to the minute magnetic field as a detection voltage or a detection current of the coil A detection signal output step of outputting a signal, and a signal analysis step of analyzing the detection signal to analyze the signal in order to identify the metal foreign matter, and the minute magnetic field is applied to the coil. The magnetic flux density (B) and magnetic field (H) representing the magnetization characteristics are close to 0 out of the magnetization (BH) characteristics of the core constituting the coil. The current or voltage is a frequency of several hundreds of Hz to several tens of kHz, and the frequency changes when the metal foreign object passes near the coil. It is characterized by being.

  In the metal foreign object detection device of the present invention, the current supplied to the sensor coil or the applied voltage is not limited to the above-mentioned frequency, but supplies an alternating current from a direct current to several hundred Hz. Even if the sensor coil is not actively supplied with current or applied with a voltage, a bias voltage of the amplifier is applied to detect the metallic foreign matter of the magnetic material. When the object to be inspected passes near the sensor coil, the magnetic field generated from the magnetic material in the object to be inspected cuts the sensor coil and changes its state, and this is detected by the sensor coil and subsequent signal processing.

  The metal foreign object detection device of the present invention can detect a magnetic substance in an object to be inspected that is a non-metallic object with high sensitivity. Furthermore, it is possible to detect a magnetic substance in an object to be inspected having a packaging bag or container wrapped with a conductive material such as aluminum or aluminum alloy.

According to the present invention, the following effects can be obtained.
The metallic foreign object detection device of the present invention can be miniaturized by using a small roller conveyor on the sliding surface, and can also be used on a desktop.

  The metal foreign object detection device of the present invention can adjust the inclination angle of the sliding surface with an adjusting tool, and can adjust the inclination angle of the sliding surface freely according to the application.

FIG. 1 is an external view showing an external appearance of a metal foreign object detection device 1 according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing an outline of the front of the metallic foreign object detection device 1 according to the embodiment of the present invention, and is a front view of FIG. FIG. 3 is a conceptual diagram showing an outline of a plane of the metal foreign object detection device 1 according to the embodiment of the present invention, and is a plan view of FIG. FIG. 4 is a conceptual diagram showing an outline of a side surface of the metal foreign object detection device 1 according to the embodiment of the present invention, and is a side view of FIG. 5A and 5B are diagrams showing a configuration example of the sensor coil of the sensor 3. FIG. 5A is a front view of the sensor coil, FIG. 5B is a plan view of FIG. 5A, and FIG. FIG. 6 is a cross-sectional view taken along line AA in FIG. FIG. 6 is a diagram illustrating an example of the structure and arrangement of the magnet booster 4. FIG. 6 (a) is a front view of the magnet booster 4, and FIG. 6 (b) is a plan view of the magnet booster 4 in FIG. 6 (a). FIG. 6C is a diagram showing an arrangement example of the magnet booster 4. FIG. 7 is a conceptual diagram showing an outline of the roller conveyor 23 of the metal foreign object detection device 1 according to the embodiment of the present invention. FIG. 8 is a diagram showing an outline of the rollers 25 of the roller conveyor 23 of the metal foreign object detection device 1 according to the embodiment of the present invention. FIG. 8 (a) is a plan view of the rollers 25 with the shaft 28, and FIG. ) Is a plan view of the roller 25 having a hollow portion, and FIG. 8C is a plan view of the shaft 28. FIG. 9 is a conceptual diagram showing how the sliding surface of the metal foreign object detection device 1 according to the embodiment of the present invention is adjusted. FIG. 10 is a functional block diagram illustrating a configuration example of the signal processing unit 16 of the metal foreign object detection device 1. FIG. 11 is a block diagram illustrating a configuration example of the digital computer processing unit 62 of the signal processing unit 16. FIG. 12 is a flowchart showing an operation example of the digital computer processing unit 62 of the signal processing unit 16.

Embodiment
FIG. 1 is an external view illustrating the external appearance of a metal foreign object detection device 1 according to an embodiment of the present invention. 2 is a conceptual diagram illustrating the outline of the front of the metal foreign object detection device 1 of FIG. 1, FIG. 3 is a conceptual diagram illustrating the outline of the plane of the metal foreign object detection device 1 of FIG. 1, and FIG. It is the conceptual diagram which illustrated the outline | summary of the side surface of the metal foreign material detection apparatus 1 of FIG. The metal foreign object detection device 1 is for detecting or detecting a metal object (magnetic substance foreign substance) in the inspection object 2 and notifying it.

  The metal foreign object detection device 1 is particularly for detecting or detecting a metal foreign object mixed in an inspection object 2 made of an inspection object filled or built in a packaging bag or the like. Although it does not specifically limit as a to-be-inspected object, Solid, liquid, or a gel-like foodstuff, the pharmaceutical with which the packaging bag was filled, etc. can be illustrated. The packaging material of a packaging bag consists of a well-known aluminum foil, a synthetic resin film, paper, a laminated material combining these materials, and the like.

[Configuration of Metal Foreign Object Detection Device 1]
The metal foreign object detection device 1 includes a box-shaped main body 6 and a slide 5 connected to one end of the metal foreign-body detection device 1 by a connecting member 15 that is a hinge. The slide 5 can swing around the connecting member 15. A sensor 3 and the like are disposed on the slide 5. When the inspection object 2 is dropped on the slide 5 by gravity within a set speed range and is slid on the sliding surface 20 of the slide 5, the sensor 3 can detect the magnetic substance in the inspection object 2. it can.

  That is, the metal foreign object detection device 1 generally guides the sensor 3 for detecting the magnetic body in the inspection object 2, the magnetizing unit 4 for magnetizing the magnetic body in the inspection object 2, and the inspection object 2. It comprises a slide 5 to be conveyed, a main body 6, an angle adjusting member (fixing member) 7 for adjusting an inclination angle of the slide 5, a detector 8 for detecting the passage of the inspection object 2, and the like. The main body 6 includes a box-shaped housing 11, a power switch 12 installed in the housing 11, a display unit 13, an operation switch 14, and a signal processing unit 16 stored in the housing 11 (see FIGS. 4 and 10). .) Etc.

  The signal processing unit 16 is an electronic circuit or a computer for performing signal processing on the signal detected by the sensor 3, determining the presence or absence of a metal foreign object, and outputting the determination result. The housing 11 is a box-shaped case for housing the power switch 12, the display unit 13, the operation switch 14, the signal processing unit 16, and the like. The housing 11 has a small structure so that it can be used on a desk. The detector 8 is a sensor for detecting whether or not an object has passed through the front, and an optical sensor is employed in this example.

  The detector 8 is mainly installed in front of the sensor 3 because the main function is to detect the timing at which the inspection object 2 passes through the sensor 3. In this example, it is installed adjacent to the sensor 3 between the sensor 3 and the magnetizing means 4. Thereby, the timing at which the inspection object 2 is conveyed and passes through the sensor 3 is accurately detected and transmitted to the signal processing unit 16. The detector 8 detects both the timing at which the inspection object 2 starts to pass in front of it and the timing at which it has passed, and transmits it to the signal processing unit 16.

  The signal indicating the passage of the inspection object 2 detected by the detector 8 can also be referred to as a passage signal of the inspection object 2. The metallic foreign object detection device 1 is basically connected to a power outlet by a power cable (not shown) and supplied with power. The power switch 12 is a switch for connecting and disconnecting a power cable in order to supply power to the metal foreign object detection device 1. When the power switch 12 is connected, power is supplied to the sensor 5, the signal processing unit 16, and the display unit 13 to operate.

  The display unit 13 is a display for displaying the overall operation status of the metal foreign object detection device 1, and is composed of, for example, a liquid crystal display. The operation switch 14 is for setting the detection sensitivity of the sensor 5 and can be adjusted in three steps in this example. The slide 5 includes a housing 21 and a sliding surface 20 installed on the upper surface thereof. The sliding surface 20 includes a small roller conveyor 23 in which a plurality of rollers 25 are arranged in parallel. An outline of the roller conveyor 23 is shown in FIG. 7 and will be described in detail later.

  The swingable casing 21 is for fixing the sliding surface 20, the sensor 3, and the magnetized portion 4, and is a hexahedral box in this example. The housing 21 is installed on the upper surface of the main body 6, and one end (right side in FIG. 1) of the housing 21 can be installed at a predetermined height from the upper surface of the main body 6. The sensor 3 and the magnetized portion 4 are fixed to the side surface of the housing 21 by support plates 34 and 44. In the example of the present embodiment, the magnetized portion 4 and the sensor 3 are installed at a predetermined distance above the sliding surface 20, and between the magnetized portion 4 and the sliding surface 20, the sensor 3 and the sliding surface 20. The inspection object 2 passes between the two.

  The inspection object 2 passes through the magnetized portion 4 and the sensor 3 while sliding from one side of the sliding surface 20 to the other side. Although not shown, guides may be provided on both sides of the sliding surface 20 so that the inspection object 2 does not slide down. Such a guide is fixed to the side surface of the housing 21 of the slide 5. As shown in FIG. 2, the sensor 3 includes a sensor coil 31 installed on the upper surface of the sliding surface 20, a sensor coil 32 installed on the lower side of the sliding surface 20, and a housing 33 for storing the sensor coil 31. And a support plate 34 for fixing the housing 33 to the slide 5.

  The sensor coil 32 is also housed in the housing and is installed below the sliding surface 20. The sensor coil 31 and the sensor coil 32 have the same structure. The sensor coils 31 and 32 detect changes in the surrounding magnetic field. A magnetic field generated from a magnetic metal such as a metal object or a metal foreign object in the inspection object 2 changes the surrounding magnetic field. In other words, the sensor coils 31 and 32 are for detecting a change in the disturbance of the surrounding magnetic field, and output a voltage or current detection signal corresponding to the change in the magnetic field.

  In the present embodiment, the casing 11 of the main body 6, the casing 21 of the slide 5, the casing 33 of the sensor 3, the casing 43 of the booster 4, etc. are made of stainless steel from the viewpoint of rust prevention and the like. . On the slide 5, the magnetized portion 4, the detector 8, and the sensor 3 are arranged in this order along the conveyance direction of the inspection object 2. The object 2 to be inspected is a solid, a liquid such as a soup stock, a paste or the like 2 individually wrapped in aluminum packaging or the like and sealed, and is conveyed while sliding on the roller conveyor 23 of the sliding surface 20. Is done. The inspection object 2 passes through the magnetized portion 4, the detector 8 and the sensor 3 in this order.

  The detection signal detected and output by the sensor 3 is transmitted to the signal processing unit 16 for signal processing. The signal processing unit 16 analyzes the detection signal received from the sensor 3 and determines whether there is a magnetic substance in the inspection object 2. The signal processing unit 16 notifies the result of this determination (electric signal, warning sound, display, etc.). When the inspection object 2 contains a magnetic material, in other words, when a defective product (metal foreign object) is detected, the signal processing unit 16 issues an alarm signal with a predetermined alarm means.

  For example, this output signal is transmitted from the signal processing unit 16 to the display 13 and displayed, and when a defective product is detected, the output signal is turned on or blinked. Alternatively, the output signal is transmitted from the signal processing unit 16 to the sound generation means, and when a defective product (metal foreign matter) is detected, an alarm signal such as a buzzer is emitted. A speaker for generating a buzzer is not shown in the figure, but is installed in the housing 11 or the like.

  The signal processing unit 16 does not need to be built in the housing 11 as in this example, and can be installed in any location as long as it can receive and process detection signals from the housing 11 by wired communication or wireless communication. You may do it. Any known communication standard can be used for the communication method of the wired communication and the wireless communication, but since it is not the gist of the present invention, detailed description thereof is omitted.

[Sensor coil]
As shown in FIG. 5, the sensor 3 of the metal foreign object detection device 1 includes two sensor coils 31 and a sensor coil 32 having the same structure. The sensor coil 31 and the sensor coil 32 are arranged up and down across the sliding surface 20. The sensor coil 31 and the sensor coil 32 have an elongated shape, and are arranged to face each other so as to be two parallel surfaces.

  The inspection object 2 passes through the space between the sensor coil 31 and the sensor coil 32 that are arranged to face each other. Both have the same structure, and the structure will be described by taking one sensor coil 31 as an example. FIG. 5 illustrates the structure of the sensor coil 31. 5 (a) is a front view of the sensor coil 31, FIG. 5 (b) is a plan view of the sensor coil 31 of FIG. 5 (a), and FIG. 5 (c) is a sectional view taken along line AA of FIG. 5 (a). It is sectional drawing. The sensor coil 31 is basically the same in the shape of an elongated bar as shown in FIG.

  The sensor coil 31 is formed of a conductive material iron core 35 having an elongated rod shape and an E-shaped cross-section, and a coil 36 wound along the groove. The iron core 35 is configured by laminating silicon steel plates or amorphous plates. For the iron core 35, a ferrite core, a permanent magnet, or the like may be used. When AC power is applied to the sensor coil 31, an alternating magnetic field is generated from the sensor coil 31 around the vicinity thereof.

  When the magnetic material passes through the alternating magnetic field, the alternating magnetic field is disturbed by the magnetic field of the magnetic material, affects the sensor coil 31, and the current flowing through the sensor coil 31 changes. The sensor coil 31 of the present invention can detect a metal foreign object having a size of 1 mm or more, but is mainly used to detect a minute metal having a size of 1 mm or less. In the side view of FIG. 2, an arrangement example of the sensors 3 is illustrated.

  The two sensor coils 31 and 32 of the sensor 3 are arranged with the coil 36 side of the E-type iron core 35 facing each other. This is configured in this way to detect the upper and lower portions of the inspection object 2 with high sensitivity. Further, by providing the two sensor coils 31 and 32, the inspection object 2 is detected by the sensor coils 31 and 32 when the inspection object 2 moves in the hollow portion between them. Since the inspection object 2 is detected by the two sensor coils 31 and 32 from above and below, the metal foreign matter is detected with high sensitivity. The metal foreign matter in the inspection object 2 can be detected with only one of the sensor coil 31 or the sensor coil 32.

  The sensor coil 31 uses a non-linear portion having a minute value in which the magnetic flux density (B) indicating the magnetization characteristic and the magnetic field (H) are close to zero, among the magnetization (BH) characteristics of the coil 36, and Perform detection. Since the technical idea about this magnetization characteristic and its utilization method is described in detail in Patent Document 1, only the gist thereof will be described. All or part of the invention described in Patent Document 1 has substantially the same structure and circuit as the present invention, and these constitute the present invention. However, the voltage, current, and frequency applied to the sensor coil 31 may be all or part of values different from those in Patent Document 1 in the embodiment of the present invention.

  Even if no current is supplied or no voltage is applied to the sensor coil 31, it is possible to detect a metallic foreign object in the magnetic material. For example, the bias voltage of the amplifier is applied to the sensor coil 31 in advance. As a result, the input bias current of the amplifier flows through the coil of the sensor coil 31. When the magnetic flux crossing the sensor coil 31 changes along with the change of the peripheral magnetic field, the current and / or voltage flowing through the sensor coil 31 changes and becomes an output signal.

  When an AC power supply of several kHz is applied to the sensor coil 31, an alternating magnetic field is generated in the sensor coil 31. When a fine stainless steel piece approaches the vicinity of the sensor coil 31, the fine stainless steel piece is magnetized by the action of a static magnetic field to generate a magnetic pole. For example, in austenitic stainless steel (SUS304, etc.), a portion having weak magnetism caused by martensite-induced transformation due to plastic deformation such as fracture, crushing, bending, chipping, etc. is magnetized by the action of a static magnetic field to form a magnetic pole. Cause it to occur.

  This change in magnetic pole affects the alternating magnetic field, and this is detected by a detection circuit including the sensor coil 31. In particular, since this effect becomes more significant as the inspection object 2 approaches the sensor coil 31, it is possible to reliably detect the metallic foreign object of the minute fragments in the inspection object 2 by the sensor coil 31. Examples of the magnetic material mixed as foreign matter in the inspection object 2 include ferromagnetic materials such as iron, nickel, and cobalt, alloys thereof, martensitic stainless steel, and the like.

  When the pair of sensor coils 31 are arranged on two sides of the bridge circuit, when a constant AC voltage is applied, the current flowing through the bridge circuit composed of the sensor coils 31 does not change, and the output current of the bridge circuit is constant. When the magnetic material passes near the sensor coil 31, the form of the alternating magnetic field is disturbed, and the output current of the bridge circuit changes. This output current is signal-processed by the signal processing unit 16 at the subsequent stage and detected as a foreign substance in the inspection object 2.

[Magnet booster]
As shown in FIG. 2, the magnetizing unit 4 includes a magnet booster 41 installed on the upper surface of the sliding surface 20, a magnet booster 42 installed on the lower side of the sliding surface 20, and a housing for storing the magnet booster 41. 43 and support means 44 for fixing the housing 43 to the slide 5. Although not shown, the magnet booster 42 is also housed in the housing and is installed below the sliding surface 20.

  The magnetizing unit 4 of the metal foreign object detection device 1 according to the present embodiment is for magnetizing the magnetic body in the inspection object 2 or for enhancing the magnetization, and is made of a permanent magnet. The installation position of the magnetized portion 4 is not limited to this position. Since the magnet booster 41 and the magnet booster 42 have the same structure, the magnet booster 41 will be described as an example. FIG. 6 illustrates the structure and arrangement example of the magnet booster 41.

  6A is a front view of the magnet booster 41, FIG. 6B is a plan view of the magnet booster 41 in FIG. 6A, and FIG. 6C is a diagram illustrating an arrangement example of the magnet booster 41. The magnet booster 41 can be composed of one permanent magnet or a plurality of two or more permanent magnets. In this example, the magnet booster 41 is composed of a plurality of permanent magnets. The magnet booster 41 is arranged at a right angle to the conveyance direction of the inspection object 2.

  In other words, two elongated magnet boosters 41 and 42 are arranged in the cross-sectional direction of the inspection object 2. It arrange | positions so that the axis line of the longitudinal direction of the magnet boosters 41 and 42 may become a right angle with respect to the conveyance direction of the to-be-inspected object 2. FIG. The two magnet boosters 41 and 42 are arranged on both sides of the inspection object 2 with the magnetic poles of the magnet elements 45 facing the inspection object 2. The magnet element 45 of each magnet booster 4 and the magnet element 45 opposed to the magnet booster 4 have the same magnetic pole directed toward the object 2 to be inspected.

  As shown in FIG. 6C, the magnet element 45 and the magnet element 45 'are arranged with the same magnetic pole N facing each other. The magnetic pole elements adjacent to the magnet element 45 and the magnet element 45 'are all arranged with the same magnetic pole N facing each other. In this example, the N magnetic pole of the magnet element 45 is arranged to face the object 2 to be inspected, but the same effect can be obtained even if the S magnetic pole is used instead of the N magnetic pole. When the magnetic poles are arranged so that the same magnetic poles face each other in this way, the metallic foreign matter located on the upper portion of the inspection object 2 is magnetized by the magnet element 45.

  Similarly, a metallic foreign object located under the inspection object 2 is magnetized by the magnet element 45 '. Further, since the metal foreign matter of the object to be inspected 2 is magnetized by the repulsive force of the same magnetic poles of the magnet element 45 and the magnet element 45 ', it can be magnetized more strongly than the single object. The magnet booster 4 is composed of a plurality of magnet elements 45 made of neodymium magnets in this example. Thus, by using a strong magnet such as a neodymium magnet, the range in which the magnetic field of the permanent magnet affects the magnetic material can be greatly expanded, and the detection sensitivity of the sensor 3 can be improved.

[Slide 5]
The upper surface of the slide 5 is a sliding surface 20. Since the sliding surface 20 employs a small roller conveyor 23 (see FIG. 7), a power source such as a motor is not required. When the inspection object 2 is placed on the upper end portion of the sliding surface 20, the inspection object 2 is transported while sliding on the sliding surface 20 by its own force due to the gravity lowering force acting on its own weight. The entire sliding surface 20 may be constituted by a single roller conveyor 23, or may be constituted by arranging a plurality of small roller conveyors 23 side by side.

  FIG. 7 shows an example of a roller conveyor 23 that constitutes the sliding surface 20. As shown in FIG. 7, the roller conveyor 23 includes a frame 24 that supports the whole, a roller 25 mounted on the frame 24, a shaft 26 that holds and fixes the two frames 24 in parallel, and the like. The frame 24 may have a connecting plate 27 for connecting and fixing to the adjacent frame 24. When the sliding surface 20 is constituted by a plurality of roller conveyors 23, the frames 24 are connected and fixed by a connecting plate 27.

  The shaft 26 is for fixing the frame 24 at a predetermined distance. In this example, a rod-shaped shaft 26 is employed, and the shaft support 26 is fixed to the frame 24 with nuts 26a. As a result, the roller 25 is supported at a predetermined minute distance from the frame 24 and freely rotates. As shown in FIG. 8B, the roller 25 has an elongated rod-like shape with a circular cross section, and a through hole 25a is opened along the longitudinal axis. As shown in FIG. 8A, the shaft 28 shown in FIG. 8C is inserted into the through hole 25a.

  The shaft 28 is inserted into holes provided in the frame 24 at both ends thereof. The roller 25 freely rotates about the shaft 28. The tip of the shaft 28 that protrudes to the outside of the frame 24 can be stopped with a stopper such as a snap pin (R pin). The snap pin (R pin) is not shown in a pin hole provided at the tip of the shaft 28. Insert and stop. The slide 5 has a connecting member 15 whose one end (left side in FIG. 1) is connected to the main body 6.

  The connecting member 15 has a plate-like member fixed to the upper surface of the housing 11 and is detachably fixed to the slide 5 with a knob bolt or the like. The slide 5 can be adjusted so that the other end (the right side in FIG. 1) can be installed by moving it up a predetermined distance from the main body 6 by the angle adjusting member 7. Thereby, the inclination angle of the slide 5 can be adjusted. In this example, the angle adjusting member 7 is formed of an elongated plate-shaped stage adjusting plate.

  As shown in FIG. 9, one end of the angle adjusting member 7 is fixed to the side surface of the main body 6 by a bolt / nut mechanism 37, and the other end is adjustable to the side surface of the housing 21 of the slide 5 by a bolt / nut mechanism 38. Fixed. The angle adjusting member 7 is provided with an elongated hole 7a from the center thereof to the end on the slide 5 side. The shaft portion of the knob bolt of the bolt / nut mechanism 38 is inserted into the hole 7a and can be sliced up and down. Yes. The hole 7a is provided with a plurality of recesses 7b for step adjustment for each inclination angle of step adjustment.

  The operator lifts the handle 22 installed at one end of the slide 5, stops the knob bolt shaft portion of the bolt / nut mechanism 38 in the recess 7b of a predetermined angle, and turns the knob bolt head to tighten it. The bolt / nut mechanism 38 is a fixing mechanism for adjusting the angle of the slide 5, and any fixing mechanism can be adopted as long as the same function is realized. In FIG. 9, the 1st installation position at the time of installing the slide 5 on the main body 6 and the 2nd installation position example at the time of installing so that it may have inclination-angle (alpha) are shown in figure.

  When the slide 5 is installed on the main body 6 at the first installation position, the angle adjusting member 7 is installed along the side surface of the main body 6, and the slide 5 does not have an inclination angle (the inclination angle is 0 degree). . In the second installation position, when the slide 5 is installed on the main body 6 with a predetermined angle, the angle adjusting member 7 is fixed to the side surface of the main body 6 with a bolt / nut mechanism 38, and the slide 5 has an inclination angle α. . The angle adjusting member 7 can be adjusted to a plurality of tilt angles, and has a hole 7b at a position where the tilt angle is reached. The inclination angle α can be freely adjusted according to the type of the object to be inspected. For example, the inclination angle α can be adjusted from 5 degrees to 30 degrees.

  In this example, the inclination angle α can be adjusted in four steps of 7, 10, 15 and 20 degrees, and holes 7b are provided at four positions. The tilt angle is proportional to the transport speed of the inspection object 2, and the transport speed increases as the tilt angle increases. It can be said that switching the inclination angle is also a switching of the conveyance speed. Depending on the object to be inspected 2, it slides depending on the material of the package, in other words, the friction coefficient differs, and the conveyance speed differs.

  Therefore, the inclination angle is adjusted in order to obtain the conveyance speed suitable for the inspection object 2. As the tilt angle increases, the conveyance speed increases. The inclination angle (conveying speed) of the slide 5 can be changed freely. The roller 25 of the sliding surface 20 is made of a non-magnetic material such as synthetic resin or stainless steel plate. The metal foreign object detection device 1 of the present invention is a small size that can be used on a desktop.

  Although not limited to this in this example, the metal foreign object detection device 1 has a length (machine length) of 600 mm, a width of 345 mm, and a height of 500 mm. The inspection object 2 has a size that can pass through the sensor 3 at the maximum. Therefore, the sensor 3 has an effective detection width of 200 millimeters and a passing standard height (a distance between the sensor coil 31 and the sliding surface 20) of 70 millimeters. By setting it as such a dimension, the metal foreign material detection apparatus 1 of this invention can be installed on bases, such as a general purpose desk 9 (refer FIG.2, FIG.4 and FIG.9).

  The drop speed varies depending on the surface properties of the slide 5 and the type and properties (mass, material, liquid / solid state, etc.) of the inspection object 2. The inspected object 2 has a package made of various materials such as a metal such as aluminum, a synthetic material such as paper, vinyl, and plastic, and the surface thereof is surface-treated with a paint or the like depending on the case. Therefore, the drop speed varies depending on the material of the surface of the object 2 to be inspected, its contents, etc. even at the same inclination angle and sliding surface.

  The falling speed basically varies depending on the coefficient of friction with which the sliding surface 20 and the inspection object 2 come into contact. In other words, it depends on the material and surface layer of both. The sliding surface 20 is determined by rolling friction in the case of a roller and sliding friction in the case of a corrugated sheet, and the falling speed is determined. In the metal foreign object detection device 1, it is desirable that the inspection object 2 falls at the same speed as possible, and for this purpose, the inclination angle of the slide is adjustable. Further, the sliding surface can be exchanged in accordance with the properties of the inspection object 2.

  As described above, the slide 5 has been described by taking the small roller conveyor 23 as an example, but the roller 25 of the small roller conveyor 23 can be replaced so as to match the detection of the inspection object 2. Since the slide 5 is detachably fixed to the main body 6 by a connecting member 15, the entire slide 5 can be replaced by removing the connecting member 15. Further, the sliding surface 20 of the slide 5 can also be exchanged and adjusted according to the type and properties of the inspection object 2.

  The roller 25 is often manufactured from a material such as synthetic resin or metal, and the friction coefficient varies depending on the surface treatment of the synthetic resin or metal. It is possible to adjust the falling speed of the inspection object 2 by the difference in the friction coefficient. In the above example, the sliding surface 20 is a small roller conveyor 23, but the roller 25 can be replaced with a roller conveyor 23 having a different size. Further, the sliding surface 20 can be replaced with a roller conveyor 23 having a different friction coefficient of the roller 25.

  Furthermore, the sliding surface 20 can be a sliding surface made of flat plate or corrugated plate. The roller 25 can be replaced with a sliding surface made of a corrugated plate, and the flat plate or the corrugated plate can be fixed to the frame 24. Alternatively, the entire frame 24 and roller conveyor 23 can be replaced with a flat plate or a corrugated plate. In this way, the sliding surface 20 is detachable, and an appropriate sliding surface is selected according to the type and properties of the inspection object 2.

[Configuration Example of Signal Processing Unit 16]
FIG. 10 illustrates an outline of the signal processing unit 16. The signal processing unit 16 includes an amplification / filter circuit 60, a waveform processing unit 61, a digital computer processing unit 62, a signal output unit 63, and the like. The sensor coils 31 and 32 of the sensor 3 are connected to the amplification / filter circuit 60. Signals output from the sensor coils 31 and 32 are amplified by the amplification / filter circuit 60 and output to the waveform processing unit 61.

  The waveform processing unit 61 shapes the waveform of the input signal, converts it into a digital signal, adjusts the reception sensitivity, and outputs the digital signal to the digital computer processing unit 62. At this time, threshold processing is performed on the signal converted into the digital signal to adjust the reception sensitivity. The digital computer processing unit 62 receives the digital signal from the waveform processing unit 61 and performs signal processing to determine the presence / absence of a magnetic substance contained in the inspection object 2. The digital computer processing unit 62 outputs an output signal to the signal output unit 63 when it is determined that the magnetic material has been detected.

  The sensor coils 31 and 32 are directly connected to the electronic circuit of the amplification / filter circuit 50. A bias voltage by a DC bias circuit for operating the amplifier of the amplification / filter circuit 60 is applied to the sensor coils 31 and 32. Thereby, the sensor coils 31 and 32 are excited, and the magnetic flux of the static magnetic field generated by the magnet boosters 41 and 42 is always linked to the sensor coils 31 and 32. A weak DC fluctuation current always flows through the coils due to fluctuations in the bias voltage applied to the sensor coils 31 and 32, disturbances in the external magnetic field, and the like.

  That is, an alternating current having a frequency of the commercial power source, an alternating current having a multiple of the alternating current, and an alternating current having a frequency superimposed with an external environmental magnetic field flow while being minute. When the inspection object 2 is transported in the vicinity of the sensor coils 31 and 32 in such an excited state (flows through the sliding surface 20), the magnetic metal foreign matter contained in the inspection object 2 is magnetically polarized by the magnet boosters 41 and 42. It is magnetized in a child shape (a pair of small magnets of N and S poles). And the sensor coils 31 and 32 output the minute foreign material signal by this magnetic metal foreign material.

  Specifically, a weak induced voltage as described by Lenz's law is generated in the sensor coil. The foreign substance signal is amplified by the amplification / filter circuit 60 (gain amplifier) and output to the waveform processing unit 61 and the digital computer processing unit 62. The amplification / filter circuit 60 amplifies the output of the sensor coils 31 and 32 to several tens to several hundred dB, and in some cases, 1000 dB or more. In this example, it is amplified by about 120 dB.

[Outline of Digital Computer Processing Unit 62]
FIG. 11 is a block diagram showing an outline of the digital computer processing unit 62. The digital computer processing unit 62 is a signal processing unit including a bus 70, a memory 71, a central processing unit (CPU) 72, an input interface 73, an output interface 74, and the like. The memory 71, the CPU 72, the input interface 73, and the output interface 74 are connected to each other via a bus 70 and transmit / receive data via the bus 70.

  The output interface 74 is connected to the signal output unit 63 and outputs the output and operation status of the digital computer processing unit 62. The signal output unit 63 is connected to the display device 13 and the buzzer 17. The memory 71 is a storage device such as a ROM or a RAM. The digital computer processing unit 62 executes a program stored in the memory 71 by the CPU 72 and determines a metal foreign object in the inspection object 2. In particular, this program causes the central processing unit 72 to execute each step of the flowchart shown in FIG.

  The digital computer processing unit 62 can be realized by a circuit unit having the same function as that of an analog circuit or a digital circuit, but detailed description thereof is omitted here. The CPU 72 controls the operation of the digital computer processing unit 62, and controls the operation of the digital computer processing unit 62 by a calculation program stored in the memory 71.

  Although not shown, the digital computer processing unit 62 can include input devices such as a mouse, a keyboard, and a touch panel. These input devices are connected to an input interface and operated by an administrator of the metal foreign object detection device 1. This is used for initialization and setting of the metallic foreign object detection device 1. The calculation program is stored in the memory 71. The calculation program is stored in the ROM of the memory 71. Alternatively, the calculation program is stored in an auxiliary storage device (not shown). In this case, the calculation program is called from the auxiliary storage device, expanded in the memory 71, and operates.

[Magnetic detection flow]
FIG. 12 is a flowchart when the digital computer processing unit 62 processes the detection signal to detect the magnetic material. In the digital computer processing unit 62, the magnetic material (metal foreign matter) in the inspection object 2 is determined. First, the digital computer processing unit 62 acquires the transport speed Vb at which the inspection object 2 is transported and stores it in the memory 111 (step 10).

  The conveyance speed Vb is obtained by inputting the value of the inclination angle α. The transport speed Vb is preferably a value stored in advance in the memory 111 or a standard value. The inspection object 2 is basically transported at the same transport speed because the set inclination angle is the same. Therefore, the conveyance speed Vb or the inclination angle α is set in advance and stored in the memory 111. The digital computer processing unit 62 receives the detection signal of the sensor 3 from the waveform processing unit 61 and stores it in the memory 111 (step 11).

  And the time t1 which received the detection signal of the sensor 3 is acquired, and it stores in the memory 111 (step 12). The time t1 is basically the value at which the detector 8 starts to pass the inspection object 2. From these values, the position of the magnetic material is calculated (step 13). Then, the detection signal received from the sensor 3 is subjected to waveform analysis and compared with standard data (comparison waveform) to determine whether the detection signal is a detection signal indicating a metal structure (steps 14 and 15).

  The metal structure included in the object to be inspected 2 has a uniform size and material. Therefore, the waveform of the detection signal is basically the same pattern for each type of metal structure. Therefore, the waveform of a metal structure that is included in the inspection object 2 and is known in advance is measured in advance and stored in the memory 111. Specifically, the standard data serving as a reference for the foreign substance signal waveform is compared with the detection signal output from the sensor 3, and the metallic foreign substance is identified based on how similar the standard data and the detection signal are.

  This is a kind of pattern matching. In this comparison, comparison items such as the amplitude of the detection signal waveform, the number of peaks, the magnitude relationship between peaks before and after the waveform of the detection signal being compared, the frequency difference, the integral value, and the differential value are compared with the standard data. Then, the difference amount is calculated. However, in this comparison, the detection signal and the standard data hardly match completely. The detection signal and the standard data are determined to be a metal foreign object when the value of the predetermined comparison item matches the standard data at a predetermined value or more, for example, 75% or more.

  Therefore, the detection signal is subjected to waveform analysis in step 14 described above, and is compared with standard data (comparison waveform) to determine whether the detection signal is a detection signal indicating a metal structure. As described above, when the detection signal matches the standard data at a predetermined ratio or more, an error due to the difference in the conveyance speed is absorbed. If it is determined in step 15 that the waveform of the detection signal does not correspond to the standard waveform, in other words, a metal foreign object, a detection signal or an alarm signal is issued (step 16).

  If it is determined in step 15 that the waveform of the detection signal is a waveform corresponding to the standard waveform, a normal signal is output (step 17). If the sensor 3 does not output a detection signal, an output signal indicating normality is output (step 11 → 17). It is preferable that the output signal indicating that the signal is normal is basically an output signal that does not output a signal or has a certain level. A series of determinations are performed in such a procedure. And after issuing an output signal, detection is performed from the above-mentioned step 10 (step 18).

  The present invention may be used for the detection of metallic foreign objects in the field of manufacturing and service of pharmaceuticals, cosmetics, foods, etc. in the field of filling products such as packaging bags and manufacturing the products, and in the service fields such as selling them. .

DESCRIPTION OF SYMBOLS 1 ... Metal foreign material detection apparatus 2 ... Test object 3 ... Sensor 4 ... Magnetization part 5 ... Slide 6 ... Main body 7 ... Angle adjustment member 8 ... Detector 11 ... Case (of the main body 6) 12 ... Power switch 13 ... Indicator DESCRIPTION OF SYMBOLS 14 ... Operation switch 15 ... Connecting member 16 ... Signal processing part 20 ... Sliding surface 21 ... Housing (of slide 5) 22 ... Handle 23 ... Roller conveyor 24 ... Frame 25 ... Roller 26 ... Supporter 27 ... Connecting plate 28 ... Shaft 31, 32 ... Sensor coil 33 ... Housing (for sensor 3) 34 ... Support plate (for sensor 3) 35 ... Iron core 36 ... Coil 37, 38 ... Knob bolt 41, 42 ... Magnet booster
DESCRIPTION OF SYMBOLS 43 ... Housing | casing (magnetization part 4) 44 ... Supporting plate 45 (magnetization part 4) 45 ... Magnet element 51 ... Oscillation circuit 52 ... Bridge circuit 53 ... Aluminum signal cancellation circuit 54 ... Amplification / phase conversion circuit 55 ... Amplification / phase Inverting circuit 56 ... Waveform processing unit 57 ... Digital computer processing unit 58 ... Signal output unit 60 ... Amplification / filter circuit 61 ... Waveform processing unit 62 ... Digital computer processing unit 63 ... Signal output unit 70 ... Bus 71 ... Memory 72 ... Central processing Device (CPU)
73 ... Input interface 74 ... Output interface

Claims (6)

A transport means for transporting the inspection object using gravity of the mass of the inspection object itself on an inclined surface which is a conveyance path;
In order to magnetize or reinforce the magnetic material in the inspection object, magnetizing means provided in the middle of the transport path;
Sensor means that is provided in the middle of the transport path and next to the magnetizing means in the transport direction of the inspection object, and outputs a detection signal;
In the metal foreign object detection device comprising: a detection means including a signal processing unit that obtains the detection signal and performs signal processing to determine the presence or absence of the magnetic body and outputs an output signal indicating the determination result;
The metal foreign matter detection device, wherein the conveyance path includes angle adjustment means for adjusting an angle of the inclined surface. In the metal foreign object detection device according to claim 1,
The sensor means is formed by winding a lead wire around a core, and uses a non-linear portion of a minute value where the magnetic flux density (B) and magnetic field (H) of the magnetization (BH) characteristic of the core are near zero. It comprises a sensor coil that detects a change in the magnetic field of the sensor and outputs the detection signal. In the metallic foreign matter detection device according to claim 1 or 2,
The metal foreign object detection device, wherein the transport path is detachably attached to a casing that forms a main body of the metal foreign object detection device. In the metallic foreign matter detection device according to claim 3,
The metal foreign object detection device, wherein the conveyance surface of the conveyance path is a detachable roller conveyor. In the metallic foreign matter detection device according to claim 3,
The metal foreign object detection device, wherein the conveyance surface of the conveyance path is a detachable flat plate or corrugated plate. In the metal foreign matter inspection machine according to claim 4 or 5,
The metal foreign matter detection device, wherein the inclination angle of the conveying surface is adjusted at an angle of 7 degrees, 10 degrees, 15 degrees, and 20 degrees.

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