JP4002988B2 - Foreign matter detection method and foreign matter detection device - Google Patents

Description

  The present invention relates to a foreign matter detection method and a foreign matter detection device for detecting foreign matter mixed in an object to be inspected. The present invention relates to a foreign matter detection method and a foreign matter detection device for detecting a metal object mixed in an object to be detected that is wrapped with a paramagnetic material such as aluminum or copper, or a non-metallic packaging material such as glass, plastic, or vinyl. More specifically, the present invention relates to a packaging container made of aluminum vapor deposition or aluminum foil, a foreign matter detection method for detecting a metallic foreign matter in a bag, and a foreign matter detection device.

  In the manufacturing process of foods, pharmaceuticals, etc., containers, blades, sieves, etc. such as conveyors, washing machines, agitators, cutting machines, kneaders, steamers, etc. are subject to metal fatigue, causing peeling, breaking, peeling, scraping, chipping, etc. Enter the product as foreign matter. It is important to detect and eliminate these foreign objects. An electromagnetic sensor coil or the like is used for the magnetic metal as means for detecting foreign matter mixed in the object to be inspected.

  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 arranged in the vicinity of the sensor coil, and detection with high sensitivity is possible by enhancing the reaction of the lines of magnetic force. When the inspection object passes through the magnet booster, the magnetism is generated by the magnet booster so that the magnetism is directed in a certain direction, and the weak magnetic material inspection object in which the austenitic stainless steel is martensitic transformed is magnetized.

  The present applicant has proposed a metal object that is detected by a sensor coil (Patent Document 1). When an AC voltage is applied to two pairs of sensor coils in which a copper wire coil is wound around an E-type iron core, an alternating magnetic field is generated. At this time, two pairs of sensor coils are connected to form a balanced or unbalanced bridge circuit. As long as the alternating magnetic field is not changed, the output current of the bridge circuit is constant.

  When an object to be inspected including a magnetic substance or a magnetized metal foreign object passes between the upper and lower sides of two pairs of sensor coils generating an alternating magnetic field, the form (formation) of the magnetic field lines of the alternating magnetic field is disturbed. At this time, the current flowing through the sensor coil changes, and the output voltage of the balanced or unbalanced bridge circuit changes. Metal foreign matter can be detected by the change in the output signal voltage.

The magnet booster generates a strong magnetic field and magnetizes an object to be detected, and has a structure including a permanent magnet. When the object to be detected passing near the magnet booster is magnetized, the detection sensitivity is improved when detecting with the sensor coil.
WO 03/027659 A1

However, in the conventional method, when the object to be detected is transported by the transport path, the position of the foreign matter placed in the direction orthogonal to the transport direction of the transport path cannot be specified.
The present invention has been invented with the above technical background, and achieves the following objects.
An object of the present invention is to provide a type foreign object detection device that can accurately detect the position of a foreign object contained in an object to be inspected using a highly sensitive sensor coil that detects a metal foreign object.

In order to achieve the above object, the present invention employs the following means.
The foreign matter detection method according to the first aspect of the present invention transports an object to be inspected by a transport path, and the first sensor and the second sensor arranged at intervals in the transport direction in the middle of the transport path. A foreign matter detection method for detecting a magnetic foreign matter mixed in an inspection object, wherein the first sensor and the second sensor are on a transport surface of the transport path in a direction (z) perpendicular to the transport direction of the transport path. When the object to be inspected moves at a constant speed (Vb) on the conveyance path, the first angle (α) and the second angle (β) are arranged at clockwise angles respectively. At the time interval (t) at which the magnetic foreign object is detected by the sensor and the second sensor , and at the interval (L) between the center of the first sensor and the center of the second sensor , the object to be inspected is the transport path. The distance (x) away from the center line of
x = (L−Vb × t) / (tan (α) −tan (β))
α ≠ β
The position of the magnetic foreign material is obtained by an equation.

The foreign object detection device according to a second aspect of the present invention, the object to be inspected is conveyed by a conveyance path, and the object to be inspected by a first sensor and a second sensor arranged in the conveyance direction at intervals in the conveyance direction. A foreign matter detection device for detecting a magnetic foreign matter mixed in an object, wherein the first sensor and the second sensor are on a transport surface of the transport path with respect to a direction (z) perpendicular to the transport direction of the transport path. The first sensor is arranged so as to have a first angle (α) and a second angle (β) in a clockwise direction, respectively, and the inspection object moves at a constant speed (Vb) on the conveyance path. And the time interval (t) when the magnetic foreign matter is detected by the second sensor , and the interval (L) between the center of the first sensor and the center of the second sensor , the object to be inspected is in the transport path. the center line or et al. are separated by a distance (x) is,
x = (L−Vb × t) / (tan (α) −tan (β))
α ≠ β
It has a calculating means (1 3 ) for calculating the position of the magnetic foreign substance by an equation.

According to the present invention, the following effects can be obtained.
The foreign object detection device of the present invention can accurately detect the position of a foreign object contained in an inspection object by using two sets of sensor coils having a predetermined angle.

  FIG. 1 illustrates an outline of the foreign object detection device 1. The foreign object detection device 1 is for detecting or detecting a metal foreign object mixed in food in an aluminum packaging bag which is a container for wrapping food, particularly in a detected object. The foreign object detection device 1 includes a belt conveyor 2, a drive motor 4, a sensor storage unit 6, a signal processing unit 13, and the like. The belt conveyor 2 is a belt conveyor mounted on a frame with legs, and is for conveying the object 14 to be detected.

  The belt conveyor 2 rotationally drives an endless belt 3 by a driving motor 4 provided on one side thereof, and a detected object 14 is placed on the belt 3 and conveyed. A sensor storage unit 6 is disposed around the center in the length direction of the belt 3 in the conveyance path through which the detection target 14 is conveyed. The sensor storage unit 6 incorporates a first sensor 8, a second sensor 9, an optical sensor 10, and the like for detecting a metallic foreign object of the detected object 14.

  The sensor storage unit 6 detects a metallic foreign object contained in the detected object 14 and outputs a detection signal. The detection signal output from the sensor storage unit 6 is sent to the signal processing unit 13. The signal processing unit 13 analyzes the signal from the sensor storage unit 6, determines whether there is a metal foreign object in the detected object, and notifies (warning sound, display, etc.) to that effect. .

  The first sensor 8 and the second sensor 9 have the same structure (details will be described later). As shown in FIG. 1, the signal processing unit 13 is installed on a table provided on the belt conveyor 2. The signal processing unit 13 may be installed anywhere as long as it can receive and process the signal from the sensor storage unit 6.

  The optical sensor 10 is installed on the front side of the first sensor 8 in the conveyance direction of the detected object 14, detects the timing at which the detected object 14 is conveyed and enters the first sensor 8, and performs signal processing on this detection. This is for transmission to the unit 13. The optical sensor 10 may be of any shape / system as long as it can detect the timing when an object to be detected enters the first sensor 8.

  The drive motor 4 is driven to rotate the belt 3. At that time, the detected object 14 is placed on one loading side of the belt 3 and conveyed toward the other side. Then, the optical sensor 10 detects the detected object 14 and notifies the signal processing unit 13 of the timing when the detected object 14 enters the first sensor 8. The signal processing unit 13 receives the notification from the optical sensor 10, analyzes the signal of each sensor when the detected object 14 passes through the first sensor 8 and the second sensor 9, and detects a metal foreign object on the detected object 14. To determine if it is included.

  If a metallic foreign object is included, the signal processing unit 13 outputs an output signal to that effect. This output signal is sent to another device (not shown) such as an electric arm provided in or connected to the foreign object detection device 1 to perform necessary processing such as removing an object to be detected including metal foreign objects. Is called. Further, in order to grasp the speed of the belt 3 being driven, the signal processing unit 13 needs to be able to receive signals such as the number of rotations of the driving motor 4. When a metal foreign object is detected by the sensor storage unit 6, the magnet booster 5 is disposed in front of the sensor storage unit 6 to magnetize the metal foreign object.

  The magnet booster 5 is composed of two pairs of magnets 7 and is arranged above and below the belt 3 so that the detected object 14 can pass between them. The sensor storage unit 6 includes a first sensor 8 and a second sensor 9. The first sensor 8 is composed of a pair of sensor coils 11 arranged above and below the belt 3. Similarly, the second sensor 9 is composed of a pair of sensor coils 12.

  FIG. 2 illustrates an outline of a method for arranging the sensor coils 11 and 12. The first sensor 8 and the second sensor 9 are installed at a distance L along the belt 3. The first sensor 8 and the second sensor 9 are provided so as to make a predetermined angle in the conveying direction of the belt 3. The sensor coil 11 of the first sensor 8 and the sensor coil 12 of the second sensor 9 leave a certain gap on the belt 3 in order for the detected object 14 flowing on the belt 3 to pass therethrough. It is installed above and below.

  The optical sensor 10 installed in front of the first sensor 8 is necessary for specifying the timing at which the detected object 14 is input to the first sensor 8. The timing at which an object to be detected is input to the second sensor 9 can be calculated based on the time input to the first sensor 8, the distance L, and the conveyance speed of the belt 3. The conveying speed of the belt 3 can be calculated from the rotational speed of the driving motor 4. Since this calculation is a well-known technique and is not the gist of the present invention, its description is omitted.

  Each of the sensor coils 11 and 12 is basically the same in the shape of an elongated bar as shown in FIG. FIG. 3 illustrates the structure of the sensor coils 11 and 12. Since the sensor coils 11 and 12 have substantially the same structure, only the sensor coil 11 will be described as an example. The sensor coil 11 has a configuration in which a coil 15 is wound along a groove portion of an iron core 16 made of a conductive material having an elongated bar shape and a cross-sectional structure having an E shape. The iron core 16 is configured by laminating silicon steel plates or amorphous plates.

  When an AC power supply of several KHz is applied to the sensor coil 11, an alternating magnetic field is generated in the sensor coil 11. When a small stainless steel fragment approaches the sensor coil 11, for example, austenitic stainless steel (SUS304, etc.) causes martensite-induced transformation due to plastic deformation such as fracture, crushing, bending, and chipping, and has weak magnetism. The magnetized portion is magnetized by the action of a static magnetic field to generate a magnetic pole. This change in the magnetic pole affects the alternating magnetic field, and this is detected by the detection circuit.

  In particular, since this effect appears greatly in the vicinity of the sensor coil 11, it is possible to reliably detect minute debris with the sensor coil 11. The same applies to ferromagnetic materials such as iron, nickel, cobalt contaminants, alloys thereof, martensitic stainless steel, and the detection sensitivity is significantly improved as compared with the prior art. When the pair of sensor coils 11 are on the two sides of the bridge circuit, the current flowing through the bridge circuit does not change when a constant AC voltage is applied, and the output current of the bridge circuit is constant. When the magnetic material passes near the sensor coil 11, 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 13 at the subsequent stage and detected as a foreign substance in the inspection object 14. The inspection object 14 is conveyed by the belt 3 and passes through the magnet booster 5. Then, it passes through the sensor coils 11 and 12. The conveyance speed of the belt 3 can be adjusted within a predetermined range. When the inspection object 14 passes through the magnetic field generated by the magnet booster 5, the metal foreign matter in the inspection object 14 is magnetized.

  FIG. 2 illustrates how the sensor coils 11 and 12 are arranged. The sensor coil 11 and the sensor coil 12 are arranged at a predetermined angle θ. The sensor coil 11 is disposed so as to form an angle α with respect to a direction orthogonal to the conveyance direction of the belt 3 and the conveyance direction of the detected object 14. The sensor coil 12 is disposed so as to form an angle β with respect to a direction perpendicular to the conveyance direction of the belt 3 and the conveyance direction of the detected object 14. The angles α and β are clockwise angles with the direction perpendicular to the conveying direction. As shown in FIG. 2, the angle α is positive and the angle β is negative. Hereinafter, the calculation is performed with the angle with the direction perpendicular to the transport direction as a positive value.

  The sensor coils 11 and 12 are arranged so as not to be parallel. If two angles of the angles θ, α, and β between the sensor coil 11 and the sensor coil 12 are known, the remaining angles can be calculated (see Equation 3 below). The centers of the sensor coil 11 and the sensor coil 12 are separated by a distance L along the conveying direction of the belt 3. When the detected object 14 is transported out of the center line of the belt 3, it can be calculated how much the detected object 14 is shifted from the center line of the belt 3 if the arrangement of the sensor coils 11 and 12 is known. This calculation is performed in the signal processing unit 13.

If the distance L and the angles α and β are known, the distance x that the detected object 14 is away from the center line of the belt 3 can be calculated. The distance x can be calculated by the following formula.
z = Vb × (t2−t1) (Formula 1)
x = (L−z) / (tan α−tan β) (Formula 2)
θ = α−β (Formula 3)
α ≠ β (Formula 4)
Here, Vb is the belt conveyance speed, t1 and t2 are times when foreign matters are detected by the first sensor and the second sensor, respectively, and L is an interval between the first sensor and the two sensor coils.

t1 is the time when the foreign matter is detected by the first sensor, and t2 is the time when the foreign matter is detected by the second sensor. t1 and t2 may be real time or relative time when the foreign object is detected. When the sensor coil 11 and the sensor coil 12 are arranged in parallel, L = z and x becomes 0 as calculated from Equations 1 and 2. Therefore, the position of the foreign object cannot be specified.

  FIG. 4 is a flowchart showing a procedure for calculating and specifying the position of the foreign substance in the signal processing unit 13. The signal processing unit 13 needs to input data on the speed of the belt 3 and the arrangement of the sensor coils 11 and 12 in advance. The detection procedure is shown below. The signal processing unit 13 acquires the conveying speed Vb of the belt 3 from the rotational speed of the driving motor 4 and stores it in the memory (step 1). The arrangement angle α of the first sensor 8 and the arrangement angle β of the second sensor 9 described above are acquired and stored in the memory (steps 2 and 3).

  The distance L between the first sensor 8 and the second sensor 9 is acquired and stored in the memory (step 4). Wait until the inspection object 14 is carried in (steps 5 and 6). When the inspection object 14 is carried in, since it passes through the optical sensor 10, it waits until a signal comes from the optical sensor 10. A foreign object signal is received from the first sensor 8 (step 7). Time t1 is acquired and stored in the memory (step 8). After waiting for a predetermined time, a foreign object signal is received from the second sensor 9 (steps 9 and 10). Time t2 is acquired and stored in the memory (step 11).

  The foreign substance detection interval z is calculated by equation 2 (step 12). The position x of the foreign material is calculated by Equation 1 (Step 13). The position x of the foreign matter is output (step 14). Next inspection is performed (step 15). If no foreign matter is detected by the first sensor 7 and the second sensor 10, the system waits for the next object to be detected to be conveyed (steps 7, 10 → step 15). Instead of the angle α in step 2 or the angle β in step 3, the angle β may be used. In this case, the angle β or α is calculated using Equation 3.

  The present invention is used in the production of foods and pharmaceuticals. Moreover, you may utilize for manufacture fields, such as a coating material.

FIG. 1 is a diagram illustrating an outline of a foreign object detection device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an outline of a sensor coil arrangement method. FIG. 3 is a diagram illustrating the structure of the sensor coil. FIG. 4 is a flowchart showing a procedure for specifying the position of a foreign object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Foreign object detection apparatus 2 ... Belt conveyor 3 ... Belt 4 ... Motor for drive 5 ... Magnet booster 6 ... Sensor storage part 7 ... Permanent magnet 8 ... 1st sensor 9 ... 2nd sensor 10 ... Optical sensor 11, 12 ... Sensor coil 13 ... Signal processing unit 14 ... Detected object

Claims (2)

Foreign matter detection for transporting an object to be inspected by a transport path and detecting magnetic foreign matter mixed in the object to be inspected by a first sensor and a second sensor arranged at intervals in the transport direction in the middle of the transport path In the method
The first sensor and the second sensor have a first angle (α) and a second angle on the conveyance surface of the conveyance path at a clockwise angle with respect to a direction (z) orthogonal to the conveyance direction of the conveyance path , respectively. Arranged to have an angle (β),
When the object to be inspected moves on the transport path at a constant speed (Vb), the time interval (t) when the magnetic foreign matter is detected by the first sensor and the second sensor, the center of the first sensor , and the When the distance (L) from the center of the second sensor,
The distance (x) that the inspection object is away from the center line of the transport path is
x = (L−Vb × t) / (tan (α) −tan (β))
α ≠ β
A foreign object detection method comprising: obtaining a position of the magnetic foreign object by an expression. Foreign matter detection for transporting an object to be inspected by a transport path and detecting magnetic foreign matter mixed in the object to be inspected by a first sensor and a second sensor arranged at intervals in the transport direction in the middle of the transport path In the device
The first sensor and the second sensor have a first angle (α) and a second angle on the conveyance surface of the conveyance path at a clockwise angle with respect to a direction (z) orthogonal to the conveyance direction of the conveyance path , respectively. Arranged to have an angle (β),
When the object to be inspected moves on the transport path at a constant speed (Vb), the time interval (t) when the magnetic foreign matter is detected by the first sensor and the second sensor, the center of the first sensor , and the When the distance (L) from the center of the second sensor,
The distance (x) that the inspection object is away from the center line of the transport path is
x = (L−Vb × t) / (tan (α) −tan (β))
α ≠ β
A foreign matter detection device comprising: a calculation means (13) for obtaining the position of the magnetic foreign matter by a formula.

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