JPH03291595A - Abnormality detecting mechanism of metal detecting device - Google Patents

Abstract

PURPOSE:To find a decrease in metal detecting ability in its early stage and to improve the efficiency of the detecting operation by comparing the signal level from a metal detection part for a checking metallic body, which operates together with a conveying means, with a previously set level value. CONSTITUTION:The metal detection part 3 detects the checking metal tape 6 stuck on the outer peripheral surface of a belt 4 at the same time and its detection signal S1 is compared with a predetermined decision level. When the signal S1 is based upon only the tape 6, the level drops below a metal for eign matter decision level La, so a comparator 11 does not output a signal showing that metal foreign matter is found. Then when the detecting ability of the detection part 3 is normal, the level of the signal S1 becomes higher than a metal tape decision level Lb and an ability decrease finding lamp 9 does not illuminates, but when the detecting ability decreases, the signal S1 drops below the level Lb and a comprator 13 does not output a reset signal S3; and a timer circuit 15 outputs a time-up signal S4 a set time later, so a self-holding circuit 16 outputs the driving signal S5 for the lamp 9, which illuminates.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a metal detection device for detecting whether metal foreign matter is attached to raw materials, products, etc. or whether VIPs are present. This relates to an anomaly detection mechanism for early detection.

[Prior Art] Conventionally, this type of metal detection device includes a heald conveyor that circulates to convey objects to be detected, and a belt conveyor that is disposed in the middle of the rotation path of the belt conveyor and emits a high-frequency magnetic field.
It is generally comprised of a metal detection section that outputs a signal with a level corresponding to the disturbance of the magnetic field. This metal detection device detects whether metal foreign matter is attached to or mixed in the object to be detected, based on the signal level from the metal detection section for the object to be detected.

If the metal detection ability of the metal detection device decreases for some reason, a problem arises in that it is no longer able to detect metal foreign matter even if the metal foreign matter is attached to or mixed in the object to be detected. Conventionally, therefore, a method has been adopted in which a test piece mixed with metal foreign matter is used to check whether the metal foreign matter can be detected normally to check for a decline in the detection ability of the metal detection device.

[Problem to be solved by the invention] However, the method of checking metal detection ability using a test piece is manual and difficult to perform frequently.
In reality, this is only done at regular intervals (for example, once every half day). Therefore, the time between one check and the next check is long, resulting in a delay in discovering a decrease in detection ability. This means that when a decrease in metal detection ability is detected as described above, it is unclear whether metal foreign matter was attached to or mixed in the detected object that was checked after the previous check. It means that. Therefore, it is necessary to re-check the specimens and excavated bodies that were previously determined to have no metal foreign matter attached or mixed in them, which has been a factor in reducing the efficiency of metal detection work.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to be able to detect the decline in metal detection ability at an early stage even if the metal detection ability has deteriorated due to some reason, and to improve metal detection work. An object of the present invention is to provide an abnormality detection mechanism for a metal detection device that can improve efficiency.

[Means for Solving the Problems] Therefore, in order to achieve the above object, the present invention provides a transport means for transporting a detected object, and a method for preventing metal foreign matter from adhering to or mixing with the detected object in the path of the transport means. a metal detection unit configured to output a signal when the metal detection unit is in the state of the metal detection unit, a metal detection unit for checking that moves with the drive of the conveying means, a signal level from the metal detection unit for the metal detection unit for checking, and a predetermined level. an abnormality detection mechanism of a metal detection device, comprising a comparison means for comparing the level value obtained by the comparison means, and a warning means for detecting and warning a decrease in the detection ability of the metal detection section based on the comparison result by the comparison means. This is a summary.

[Operation] By employing the above configuration, the checking metal body is moved by the drive of the conveyance means when the metal detection section is activated. The metal detection section detects a check metal object and outputs a signal of a level corresponding to the detection of the metal object. The signal from the metal detection section is compared with a predetermined level value by the comparing means. At this time, if the metal detection ability of the metal detection section is reduced, the signal level from the checking metal body becomes low. Therefore, based on the comparison results by the comparison means,
The warning means can detect a decrease in the detection ability of the metal detection section.

[Example] An example embodying the present invention will be described below with reference to the drawings.

FIG. 2 is a perspective view schematically showing the metal detection device of this embodiment, and the metal detection device 1 includes a belt conveyor 2 as a conveying means and a metal detection section 3. The belt conveyor 2 has a well-known structure in which an endless belt 4 is driven around by a drive motor (not shown).
The object to be detected 5, which is supplied onto the belt 4 from the right side of the figure, is conveyed forward.

The metal detection section 3 has a square tube shape with the front and back open, and is arranged so as to surround the belt 4 at the upper center of the belt conveyor 2, which is the conveyance path for the detected object 5. A transmitting coil 17 is installed in the bottom wall of the metal detection section 3, and a pair of receiving coils 18 is installed in the earthen wall, and a high frequency magnetic field is transmitted from the transmitting coil 17 to the receiving coil 18. When the magnetic field is disturbed by the passage of a detected object 5 containing a metal foreign object M or a metal tape 6 described later, the metal detection section 3 amplifies and outputs a signal with a level corresponding to the disturbance of the magnetic field. It has become.

On one side of the outer circumferential surface of the belt 4 of the belt conveyor 2, a large number of metal tapes 6 as checking metal bodies are adhered over the entire circumference of the belt 4 in close proximity to each other. Therefore, when the belt conveyor 2 is driven, each metal tape 6 rotates together with the belt 4, and these metal tapes 6 pass through the metal detection section 3 intermittently.

The metal tape 6 is formed of stainless steel foil so that the amount of disturbance in the magnetic field detected by the metal detection section 3 is weaker than the amount of disturbance in the magnetic field caused by the metal foreign object M.

The metal detection section 3 includes a metal foreign object detection buzzer 8 as a warning means that emits a warning sound when a metal foreign object M is detected, and a capability reduction detection lamp that lights up when the detection ability of the metal detection section 3 decreases. 9 and a control device lO for driving and controlling these are attached.

Next, the electrical configuration of this control device 10 will be explained with reference to FIGS. 1-3.

One input terminal of a first comparator 11 is connected to the metal detection section 3, and a first judgment level generator 12 is connected to the other input terminal of the first comparator 11. The detection signal S1 output from the metal detection section 3 is the same as the detection signal Sea when the metal foreign object M and the metal tape 6 pass through the metal detection section 3 when the metal detection section 3 is functioning normally. It is composed of a combination of a detection signal Sob when only the metal tape 6 passes through the metal detection section 3 during normal functioning, and a detection signal Sac when the detection ability of the metal detection section 3 is reduced.

From the first judgment level generator 12, a metal detection section 3
During normal functioning, a metal foreign object determination level La, which is a slightly lower level than the detection signal Ski when the metal foreign object M and the metal tape 6 pass through the metal detection section 3, is output. The first comparator 11 receives a detection signal S from the metal detection section 3.
1 and the metal foreign matter determination level La, the detection signal S1
When becomes equal to or higher than the metal foreign object determination level La, a signal S2 for driving the metal foreign object detection buzzer 8 connected to the output terminal of the first comparator 11 is output.

Further, one input terminal of a second comparator 13 is connected to the metal detection section 3, and a second determination level generator 14 is connected to the other input terminal of the second comparator 13. .

From this second judgment level generator 14, the metal detection unit 3
During normal functioning, a metal tape determination level Lb, which is a slightly lower level than the detection signal Srb output when the metal tape 6 passes the metal detection section 3, is output. The second comparator 13 receives the detection signal S1 from the metal detection section 3.
is compared with the metal tape judgment level Lb, and the detection signal S1
When becomes equal to or higher than the metal tape determination level Lb, the second comparator 13 outputs a set signal S3S for starting time measurement or a reset signal S3r for stopping time measurement by the timer circuit 15 connected to the output terminal. Second comparator 13
After the timer circuit 15 starts measuring time based on the set signal S3S from the timer circuit 15, when the reset signal S3r is not input and a preset time T elapses, the timer circuit 15 outputs a time-up signal S4.

A capability deterioration detection lamp 9 is connected to the timer circuit 15 via a self-holding circuit 16 consisting of a flip-flop, and this self-holding circuit 16 drives the capability deterioration detection lamp 9 based on a time-up signal S4 from the timer circuit 15. A signal S5 is output for the purpose. This signal S5 continues to hold its output value by the self-holding circuit 16 even if the timer circuit 15 outputs the set signal S3S after the time-up signal S4 is output.

Next, the operation of the metal detection device 1 of this embodiment configured as described above will be explained with reference to the time chart shown in FIG.

When the detected object 5 is supplied to the belt conveyor 2, the detected object 5 is conveyed forward by the rotation of the belt 4.

In the metal detection section 3, a high frequency magnetic field is transmitted from the transmitting coil 17 toward the receiving coil 18, and it is detected whether or not the magnetic field is disturbed by passing through the metal. At this time, if no metallic foreign matter M is attached to or mixed in the object 5 to be detected, the magnetic field will not be significantly disturbed by the object 5 to be detected. However, since a large number of metal tapes 6 are attached to the outer peripheral surface of the belt 4 in close proximity to each other,
The magnetic field is slightly disturbed by these metal tapes 6.

When a detection signal Sob having a level corresponding to the disturbance of the magnetic field is output from the metal detection section 3, this detection signal Sob is input to the first comparator 11 and compared with the metal foreign matter determination level La. Since the detection signal Sob from the metal detector 3 is based only on the metal tape 6, the detection signal S1b is lower than the metal foreign matter determination level La. Therefore, the first comparator 11 does not output a signal for driving the metal foreign object detection buzzer 8.

Further, the detection signal Slb from the metal detection section 3 is compared with the metal tape determination level Lb by the second comparator 13. When the metal detection section 3 is functioning normally, the detection signal S1b is equal to or higher than the metal tape judgment level Lb, so the second comparator 13 outputs the set signal Sas for driving the timer circuit 15. Output. The timer circuit 15 starts counting time based on this set signal Sas, but the timing is stopped by the reset signal S3r that is subsequently output.

Since the second comparator 13 outputs the set signal S3S and the reset signal Ssr intermittently, the timer circuit 15 repeatedly starts and stops timing based on these signals. Therefore, the time-up signal S4 is not outputted from the timer circuit 15 to the self-holding circuit 16, and the performance degradation detection lamp 9 is not lit.

When the object to be detected 5 to which the metal foreign matter M is attached or mixed passes the metal detection section 3 at time t1, for example, the high frequency magnetic field of the metal detection section 3 is greatly disturbed by the metal foreign matter M.

When a detection signal S with a level corresponding to this disturbance of the magnetic field is output from the metal detection section 3, the detection signal 81m is higher than the metal foreign object determination level La, so the first comparator 11 detects the metal foreign object. A signal S2 for driving the buzzer 8 is output. This signal S2 triggers a metal foreign object detection buzzer 8.
is activated, the operator can know that the metal foreign matter M is attached to or contained in the detected object 5.

By the way, when the metal detecting ability of the metal detecting section 3 decreases and the detection signal S1c output from the metal detecting section 3 becomes lower than the metal tape determination level Lb at time tz, the second comparator 13 outputs a timer signal. A reset signal Sir for stopping time measurement in the circuit 15 is not output. When this state continues and a preset time T has elapsed to reach time t3, the timer circuit 15 outputs a time-up signal S.
4 is output to the self-holding circuit 16. The self-holding circuit 16 outputs a signal S5 for driving the performance deterioration detection lamp 9 based on the time-up signal S from the timer circuit 15. Therefore, the operator can know that the metal detection ability of the metal detection section 3 has decreased by lighting the ability decrease detection lamp 9.

As described above, according to the present embodiment, even if the metal detection ability of the metal detection section 3 decreases due to some cause, the decrease in the detection ability can be detected early and reliably.

Therefore, compared to the conventional technique in which a test piece is manually used at regular intervals, it is possible to improve the efficiency of metal detection work and the reliability of detection ability.

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, and may be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) As the metal body for checking in the above embodiment,
In addition to the metal tape 6 made of stainless steel foil, foil made of metal such as aluminum or iron, or a base material coated with metal vapor deposition may be used.

(2) In the checking metal body 6 in the above embodiment, one long metal tape 6 is attached to the belt of the belt conveyor 2.
As long as they are not attached over the entire circumference, the number, length, width, attachment location, etc. can be changed as appropriate.

(3) In the metal detection device l using the metal detection section 3 described above, the detection sensitivity (the magnitude of the output signal) of the metal detection section 3 is determined by the angle of the magnetic field with respect to the detected object 5 (so-called phase angle). It has the property of changing. The relationship between this phase angle and detection sensitivity differs depending on the type of metal.

Therefore, if the type of metal constituting the metal foreign matter M mixed in the object to be detected 5 is known in advance, it is possible to use a thick metal body as the checking metal body 6. In this case, it is sufficient to select a metal different from the constituent metal of the foreign metal object M, and to set a phase angle such that the detection sensitivity for the metal foreign object M is high and the detection sensitivity for the checking metal body 6 is low.

(4) In the embodiment described above, the ability deterioration detection lamp 9 was used as a warning means when the metal detection ability decreased and was turned on, but the belt conveyor 2 was stopped or a buzzer sounded. Good too.

(5) The abnormality detection mechanism of the present invention can be applied to metal detection devices for foods, medicines, sewn products, iron and steel, etc.

[Effects of the Invention] As detailed above, according to the abnormality detection mechanism of the present invention, even when the metal detection ability of the metal detection section decreases,
This makes it possible to detect the decline in detection ability early and reliably. Therefore, it is possible to improve the efficiency of metal detection work compared to the conventional technique in which a test piece is manually used at regular intervals.

[Brief explanation of drawings]

The drawings show an embodiment embodying the present invention, FIG. 1 is a diagram showing the electrical configuration of a control device in a metal detection device, FIG. 2 is a perspective view showing an outline of the metal detection device, and FIG. It is a time chart for showing the action of the metal detection device. 2... Belt conveyor as a conveyance means, 3... Metal detection unit, 5... Detected object, 6... Metal tape as a checking metal object, 9... Decrease in ability as a warning means Discovery lamp, 13...Second comparator as comparison means, M...Metal foreign object.

Claims (1)

[Claims] 1. A conveying means (2) for conveying the detected object (5), and a metal foreign object (M) attached to or attached to the detected object (5) in the path of the conveying means (2). A metal detection unit (3) that outputs a signal when the metal is mixed in the metal, a checking metal body (6) that moves as the conveying means (2) is driven, and the checking metal body (6). ) metal detection part (3)
a comparison means (13) for comparing the signal level from the metal detector with a predetermined level value; and detecting a decrease in the detection ability of the metal detection section (3) based on the comparison result by the comparison means (13). An abnormality detection mechanism for a metal detection device, comprising: a warning means (9) for issuing a warning.