JP2016145804A

JP2016145804A - Metal detector

Info

Publication number: JP2016145804A
Application number: JP2015223980A
Authority: JP
Inventors: 敏隆福田; Toshitaka Fukuda
Original assignee: Saika Tech Inst Found; Saika Technological Institute Foundation
Current assignee: Saika Tech Inst Found; Saika Technological Institute Foundation
Priority date: 2015-02-04
Filing date: 2015-11-16
Publication date: 2016-08-12
Anticipated expiration: 2035-11-16
Also published as: JP6056942B2

Abstract

PROBLEM TO BE SOLVED: To improve both detection accuracy of a metal foreign matter and processing performance while suppressing an increase in manufacturing cost by use of a simple structure.SOLUTION: In a metal detector, a detection coil 3 is disposed to a radially outer side of a cylinder body 2 made of a nonmagnetic material, and a material to be sorted which is charged in a hopper 4 in a state of supplying a high frequency current to the detection coil 3 to oscillate, falls by gravity and passes through an internal space S in the cylinder body 2. The metal detector, by detecting an impedance variation generated by the detection coil 3 when a metal foreign matter in the material to be sorted passes through the internal space S, detects the metal foreign matter. A connection pipe 5 is disposed between the upper end part of the cylinder body 2 and the lower end part of the hopper 4. A length L and bore diameters D1 and D2 of the connection pipe 5 are specified and a height direction distance H from the upper end of the connection pipe to the detection coil 3 is set to 100 mm or more in such a manner that the material to be sorted that enters in the connection pipe 5 from the hopper 4 falls by gravity in a coarse state without being tightly clogged in the connection pipe 5.SELECTED DRAWING: Figure 3

Description

本発明は、樹脂ペレット等の被選別物に混入した金属異物を検出して選別する金属検出装置に関する。 The present invention relates to a metal detection apparatus that detects and sorts metal foreign matter mixed in an object to be sorted such as resin pellets.

樹脂ペレット若しくは樹脂粉粒体、又は固形食品若しくは食品粉粒体である被選別物に混入した金属異物を検出して選別する金属検出装置として、非磁性体製の円筒体の径方向外方に検出コイルを配設し、前記検出コイルに高周波電流を与えて発振させた状態で、ホッパーに投入された被選別物が重力により落下して前記円筒体の内部空間を通過し、前記被選別物内の金属異物が前記内部空間を通過する際における前記検出コイルのインピーダンス変化を検出することにより前記金属異物を検出するものがある（例えば、特許文献１ないし３参照）。
ここで、特許文献１及び２の金属検出装置（特許文献１の第１図、特許文献２の第１図及び第２図参照）は、前記円筒体の上端部に前記ホッパーの下端部が直結されており、特許文献３の金属検出装置（特許文献３の図３参照）は、前記円筒体の上端部と前記ホッパーの下端部との間に連結管を設けている。 As a metal detection device that detects and sorts out metal foreign substances mixed in the objects to be sorted, such as resin pellets or resin granules, or solid food or food granules, on the outside in the radial direction of a non-magnetic cylindrical body In a state where a detection coil is disposed and oscillated by applying a high-frequency current to the detection coil, the object to be sorted put into the hopper falls by gravity and passes through the inner space of the cylindrical body, and the object to be sorted There is one that detects the metallic foreign matter by detecting a change in impedance of the detection coil when the metallic foreign matter passes through the internal space (for example, see Patent Documents 1 to 3).
Here, in the metal detectors of Patent Documents 1 and 2 (see FIG. 1 of Patent Document 1 and FIGS. 1 and 2 of Patent Document 2), the lower end portion of the hopper is directly connected to the upper end portion of the cylindrical body. In the metal detection device of Patent Document 3 (see FIG. 3 of Patent Document 3), a connecting pipe is provided between the upper end portion of the cylindrical body and the lower end portion of the hopper.

これらのような金属検出装置における金属異物の検出精度を向上するための工夫として、前記円筒体に形成した屈曲部に前記検出コイルを設け、前記屈曲部を通過する金属異物を下方偏位させて前記検出コイルに近づけるようにして、最も検出感度が低くなる前記検出コイルの中空部の中心近傍を通過しないようにしたもの（特許文献２の第２図参照）、前記円筒体の内部空間の中心を含む鉛直軸及びその近傍域に規制部材を設け、前記内部空間を通過する金属異物が、最も検出感度が低くなる前記検出コイルの中空部の中心近傍を通過しないようにしたもの（特許文献３の図３参照）がある。 As a device for improving the detection accuracy of metal foreign objects in such metal detection devices, the detection coil is provided in a bent portion formed in the cylindrical body, and the metal foreign material passing through the bent portion is displaced downward. Close to the detection coil so as not to pass near the center of the hollow portion of the detection coil where the detection sensitivity is lowest (see FIG. 2 of Patent Document 2), the center of the internal space of the cylindrical body A regulating member is provided in the vertical axis including the vicinity thereof and in the vicinity thereof, so that the metal foreign matter passing through the internal space does not pass through the vicinity of the center of the hollow portion of the detection coil having the lowest detection sensitivity (Patent Document 3). FIG. 3).

特開平０２−１２６１８０号公報Japanese Patent Laid-Open No. 02-126180 特開昭５８−１９９０８５号公報Japanese Patent Laid-Open No. 58-199085 特開２００２−１５６４６２号公報JP 2002-156462 A

本願の発明者は、前記構成の金属検出装置における金属異物の検出精度を向上するとともに処理能力を向上するために、先行技術の構成も含む様々な構成についての検討を行い、実験及び試作等による具体化を進めることにより本発明を完成するに至った。 The inventor of the present application examines various configurations including the configuration of the prior art in order to improve the detection accuracy of the metal foreign matter and improve the processing capability in the metal detection apparatus having the above configuration, and through experiments and trial manufacture, etc. The present invention has been completed by advancing the embodiment.

前記検討の結果、従来の前記構成の金属検出装置において、前記ホッパーに投入された被選別物は密な状態のまま、前記連結管の上端からその内部空間に入って落下し始め、前記円筒体内で徐々に粗状態になり重力加速度で加速しながら前記検出コイルを通過するが、加速区間が短いと、落下速度が小さくなって検出電圧が小さくなるとともに、落下速度が小さいため処理能力が小さくなっていることが分かった。
よって、前記構成の金属検出装置において、前記検出コイルを通過する被選別物の落下速度を大きくすることにより、前記被選別物に混入した金属異物の検出精度の向上、及び処理能力の向上を両立できるという知見を得た。 As a result of the examination, in the conventional metal detection apparatus having the above-described configuration, the object to be sorted put into the hopper starts to fall into the internal space from the upper end of the connecting pipe while being in a dense state, When the acceleration section is short, the drop speed decreases and the detection voltage decreases, and the drop speed decreases and the processing capacity decreases. I found out.
Therefore, in the metal detection device having the above-described configuration, by increasing the fall speed of the object to be sorted that passes through the detection coil, both the detection accuracy of the metal foreign matter mixed in the object to be selected and the improvement of the processing capability are compatible. I got the knowledge that I can do it.

また、前記検討の結果、前記のような金属異物の検出精度を向上するための工夫（特許文献２の第２図、特許文献３の図３）では、前記円筒体の内部空間を通過する金属異物が最も検出感度が低くなる検出コイルの中空部の中心近傍を通過しないので、前記金属異物の検出精度を向上できるという一定の効果がある反面、処理能力が低下する場合があることが明らかになった。
その理由は、特許文献２の第２図の構成では、前記円筒体の２箇所の屈曲箇所が抵抗となること、特許文献３の図３の構成では、前記円筒体の内部空間の一部を前記規制部材が塞いでいることによるものである。
その上、特許文献２の第２図の構成では、前記屈曲部を含む前記円筒体（シュート管４）の製造コストが増大し、特許文献３の図３の構成では、前記規制部材（チューブ５６）及び、その支持部材（支持棒５９等）の製造コストが増大する。 In addition, as a result of the examination, in the device for improving the detection accuracy of the metal foreign matter as described above (FIG. 2 of Patent Document 2 and FIG. 3 of Patent Document 3), the metal passing through the internal space of the cylindrical body Since foreign matter does not pass near the center of the hollow portion of the detection coil where the detection sensitivity is the lowest, there is a certain effect that the detection accuracy of the metallic foreign matter can be improved, but it is clear that the processing capacity may be reduced. became.
The reason is that in the configuration of FIG. 2 of Patent Document 2, two bent portions of the cylindrical body become resistance, and in the configuration of FIG. 3 of Patent Document 3, a part of the internal space of the cylindrical body is used. This is because the restriction member is blocked.
In addition, in the configuration of FIG. 2 of Patent Document 2, the manufacturing cost of the cylindrical body (chute tube 4) including the bent portion is increased. In the configuration of FIG. ) And the manufacturing cost of the support member (support bar 59, etc.) increases.

そこで、本発明が前述の状況に鑑み、解決しようとするところは、簡素な構成により製造コストの上昇を抑制しながら、金属異物の検出精度の向上、及び処理能力の向上を両立できる金属検出装置を提供する点にある。 Therefore, in view of the above-described situation, the present invention intends to solve a metal detection device capable of simultaneously improving the detection accuracy of metal foreign matter and improving the processing capability while suppressing an increase in manufacturing cost with a simple configuration. Is to provide

本発明に係る金属検出装置は、前記課題解決のために、非磁性体製の円筒体の径方向外方に検出コイルを配設し、前記検出コイルに高周波電流を与えて発振させた状態で、ホッパーに投入された被選別物が重力により落下して前記円筒体の内部空間を通過し、前記被選別物内の金属異物が前記内部空間を通過する際における前記検出コイルのインピーダンス変化を検出することにより前記金属異物を検出する金属検出装置であって、前記円筒体の上端部と前記ホッパーの下端部との間に連結管を設け、重力により前記ホッパーから前記連結管内に入った前記被選別物が前記連結管内で密に詰まらずに粗い状態で落下するように前記連結管の長さ及び口径を定めるとともに、前記連結管の上端から前記検出コイルまでの高さ方向距離を１００ｍｍ以上としてなることを特徴とする。 In order to solve the above problems, the metal detection device according to the present invention has a detection coil disposed radially outward of a non-magnetic cylindrical body, and oscillates by applying a high-frequency current to the detection coil. The object to be sorted put into the hopper falls by gravity and passes through the internal space of the cylindrical body, and the change in impedance of the detection coil is detected when the metal foreign matter in the material to be sorted passes through the internal space. A metal detecting device for detecting the metal foreign object by providing a connecting pipe between an upper end portion of the cylindrical body and a lower end portion of the hopper, and entering the connecting pipe from the hopper by gravity. The length and the diameter of the connecting pipe are determined so that the sorted product falls in a rough state without being densely packed in the connecting pipe, and the height direction distance from the upper end of the connecting pipe to the detection coil is set to 100 m. Characterized by comprising as least.

このような構成によれば、重力によりホッパーから連結管内に入った被選別物が連結管内で密に詰まらずに粗い状態で落下するように連結管の長さ及び口径が定められているので、被選別物が連結管内で密に詰まって落下速度が低下することがない。
その上、連結管の上端から検出コイルまでの高さ方向距離が１００ｍｍ以上であるので、被選別物が重力により加速されて落下速度が上昇した状態で検出コイルを通過する。
よって、簡素な構成により製造コストの上昇を抑制しながら、被選別物に混入した金属異物の検出精度を向上できるとともに、処理能力を向上できる。 According to such a configuration, the length and the diameter of the connecting pipe are determined so that an object to be sorted that has entered into the connecting pipe from the hopper due to gravity falls in a rough state without being densely packed in the connecting pipe. The to-be-sorted object does not clog tightly in the connecting pipe, and the falling speed does not decrease.
In addition, since the height direction distance from the upper end of the connecting pipe to the detection coil is 100 mm or more, the object to be sorted passes through the detection coil in a state where the fall speed is increased due to acceleration by gravity.
Therefore, while suppressing an increase in manufacturing cost with a simple configuration, it is possible to improve the detection accuracy of the metal foreign matter mixed in the object to be sorted and improve the processing capability.

ここで、前記連結管が下方に縮径するテーパー管であると好ましい。
このような構成によれば、下方位置の被選別物の方が重力により加速されて高速であることから、連結管内で被選別物が密に詰まらないようにする断面積を小さくできるので、連結管を下方に縮径するテーパー管にすることができ、それにより連結管の下方に位置する円筒体及び検出コイルを小径化できるため、検出感度が向上する。 Here, it is preferable that the connecting pipe is a tapered pipe whose diameter is reduced downward.
According to such a configuration, since the object to be sorted in the lower position is accelerated by gravity and is high speed, the cross-sectional area can be reduced so that the object to be sorted is not clogged densely in the connecting pipe. Since the tube can be a tapered tube whose diameter is reduced downward, and the cylindrical body and the detection coil positioned below the connecting tube can be reduced in diameter, the detection sensitivity is improved.

また、前記テーパー管が２段円錐管状であり、下方に縮径する比率が上段の円錐管よりも下段の円錐管の方が小さいもの、又は前記テーパー管の下方に縮径する比率が下方へ行くに従って漸減するものであるのがより好ましい。
このような構成によれば、万が一、被選別物の大きさ等による連結管内下方での詰まりや連結管の下流側で流れが堰き止められ、連結管内で被選別物が詰まった場合において、連結管の上下方向の中間部分に滞留する被選別物の量が少なくなる。それにより、連結管内での詰まりや下流側等での流れの堰き止めが解消され、被選別物の流れが再開する際、連結管内の被選別物は下方から粗になり落下し始めるが、被選別物の滞留量が少ないことから早く滞留量が少なくなる。また、同時に上部のホッパーから被選別物が連結管に流入してくるが、このような連結管の形状により、連結管に密で低速で流入する量より粗で自由落下速度で排出する量の方が多く、密と粗の境界が次第に上方に移動し連結管内の被選別物の流れは全て粗状態になり速い落下速度（自由落下速度）に復帰しやすくなるので、使い勝手を向上できる。 Further, the tapered tube is a two-stage conical tube, and the ratio of the diameter of the lower cone is smaller in the lower cone tube than that of the upper cone tube, or the ratio of the diameter of the taper tube is decreased downward. It is more preferable that it gradually decreases as it goes.
According to such a configuration, in the unlikely event that clogging occurs in the lower part of the connection pipe due to the size of the object to be sorted or the flow is blocked on the downstream side of the connection pipe, the object to be sorted is clogged in the connection pipe. The amount of the object to be sorted that stays in the middle part in the vertical direction of the pipe is reduced. As a result, clogging in the connecting pipe and blocking of the flow on the downstream side, etc. are resolved, and when the flow of the material to be sorted resumes, the material to be sorted in the connecting pipe becomes rough from below and starts to fall. Since the retained amount of the selected product is small, the retained amount is quickly reduced. At the same time, the material to be sorted flows from the upper hopper into the connecting pipe. Due to the shape of such a connecting pipe, the amount to be discharged at a coarse and free fall speed is larger than the amount that flows into the connecting pipe densely at low speed. In many cases, the dense and rough boundary gradually moves upward, and the flow of the objects to be sorted in the connecting pipe is all in a rough state and is easy to return to a fast drop speed (free fall speed), so that the usability can be improved.

さらに、前記連結管及び前記円筒体を傾斜させた状態で配置してなるのが一層好ましい。
このような構成によれば、連結管及び円筒体内を落下する被選別物が重力の影響で管内の下方へ寄って流れ、連結管及び円筒体内の上側部分に隙間ができることから、連結管が細くて長い場合等において被選別物の流量を増やしても詰まりが発生しにくくなるので、使い勝手をさらに向上できる。 Further, it is more preferable that the connecting pipe and the cylindrical body are arranged in an inclined state.
According to such a configuration, the sorting object that falls in the connecting pipe and the cylindrical body flows downward in the pipe due to the influence of gravity, and a gap is formed in the upper portion of the connecting pipe and the cylindrical body, so that the connecting pipe is thin. In such a case, the clogging is less likely to occur even if the flow rate of the object to be sorted is increased, and the usability can be further improved.

さらにまた、前記円筒体の外周面に全周にわたる凹溝を形成し、前記凹溝内に前記検出コイルの内周面を配置してなるのがより一層好ましい。
このような構成によれば、検出コイルをさらに小径化できるので、検出感度をさらに向上できる。 Furthermore, it is even more preferable that a concave groove extending over the entire circumference is formed on the outer peripheral surface of the cylindrical body, and the inner peripheral surface of the detection coil is disposed in the concave groove.
According to such a configuration, since the detection coil can be further reduced in diameter, the detection sensitivity can be further improved.

以上のように、本発明に係る金属検出装置によれば、被選別物が連結管内で密に詰まって落下速度が低下することがなく、被選別物が重力により加速して落下速度が上昇した状態で検出コイルを通過するので、簡素な構成により製造コストの上昇を抑制しながら、被選別物に混入した金属異物の検出精度の向上及び処理能力の向上を両立できるという顕著な効果を奏する。 As described above, according to the metal detection device of the present invention, the objects to be sorted are not tightly packed in the connecting pipe and the falling speed is not lowered, and the objects to be sorted are accelerated by gravity and the falling speed is increased. Since it passes through the detection coil in a state, it has a remarkable effect that it is possible to achieve both improvement in detection accuracy of metal foreign matter mixed in the object to be selected and improvement in processing capability while suppressing an increase in manufacturing cost with a simple configuration.

本発明の実施の形態に係る金属検出装置の部分縦断面図である。It is a fragmentary longitudinal cross-sectional view of the metal detection apparatus which concerns on embodiment of this invention. 同じく平面図である。It is also a plan view. 連結管及び円筒体まわりを示す要部拡大縦断面図である。It is a principal part expansion longitudinal cross-sectional view which shows a connection pipe and the surroundings of a cylindrical body. テストピース（ＷＣ，φ0.2）を自由落下させた実験例を示しており、（ａ）は検出コイルまでの落差によるセンサ検出電圧の変化を示すグラフ、（ｂ）は検出コイルを通過する際の落下速度によるセンサ検出電圧の変化を示すグラフである。An experimental example in which the test piece (WC, φ0.2) is freely dropped is shown, (a) is a graph showing a change in sensor detection voltage due to a drop to the detection coil, and (b) is when passing through the detection coil It is a graph which shows the change of the sensor detection voltage by the fall speed of a. テストピース（ＳＵＳ３０４，φ0.3）を自由落下させた実験例を示しており、（ａ）は検出コイルまでの落差によるセンサ検出電圧の変化を示すグラフ、（ｂ）は検出コイルを通過する際の落下速度によるセンサ検出電圧の変化を示すグラフである。An experimental example in which a test piece (SUS304, φ0.3) is freely dropped is shown, (a) is a graph showing a change in sensor detection voltage due to a drop to the detection coil, and (b) is when passing through the detection coil It is a graph which shows the change of the sensor detection voltage by the fall speed of a. 落差による自由落下の落下速度の変化を示すグラフである。It is a graph which shows the change of the fall speed of free fall by a head. 連結管の形状の変形例を示す要部拡大縦断面図であり、（ａ）は２段円錐管状であり、下方に縮径する比率が上段の円錐管よりも下段の円錐管の方が小さいもの、（ｂ）は下方に縮径する比率が下方へ行くに従って漸減するものを示している。It is a principal part expanded longitudinal cross-sectional view which shows the modification of the shape of a connection pipe, (a) is a 2 step | paragraph conical tube, and the ratio of a diameter reduction below is smaller in the lower conical tube than the upper conical tube (B) shows that the ratio of diameter reduction downward gradually decreases as it goes downward. 連結管及び円筒体を傾斜させた状態で配置する構成の一例を示す模式図である。It is a schematic diagram which shows an example of a structure arrange | positioned in the state which inclined the connecting pipe and the cylindrical body.

次に本発明の実施の形態を添付図面に基づき詳細に説明する。
以下の実施の形態では、４チェンネルにして処理能力を向上した金属検出装置を示すが、要求仕様によっては、１チャンネル、２若しくは３チャンネル、又は５チャンネル以上であってもよい。なお、後述する本発明の金属検出装置における処理能力の向上により、従来の金属検出装置よりもチャンネル数を少なくできる。 Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In the following embodiment, a metal detection device having four channels and improved processing capability is shown, but depending on the required specifications, it may be one channel, two or three channels, or five or more channels. It should be noted that the number of channels can be reduced as compared with the conventional metal detection device by improving the processing capability of the metal detection device of the present invention described later.

図１の部分縦断面図、及び図２の平面図、並びに図３の要部拡大縦断面図に示すように、本発明の実施の形態に係る金属検出装置１は、筐体１Ａ、セラミック（非磁性体）製の円筒体２、円筒体２の径方向外方に配設された検出コイル３、図示しない被選別物が投入される、円筒体２の上方に位置するホッパー４、円筒体２の上端部とホッパー４の下端部との間に設けられた連結管５、円筒体２の下方に設けられたリード管６、リード管６の下方に設けられた選別ダンパー７、選別ダンパー７を揺動軸８Ａまわりに揺動させる揺動駆動装置８、金属異物を含む被選別物を機外へ排出する排出シュート９、並びに、検出コイル３に高周波電流を与えて発振させる発振手段及び被選別物内の金属異物が円筒体２の内部空間Ｓを通過する際における検出コイル３のインピーダンス変化を検出する検出手段、並びに揺動駆動装置８の駆動制御手段を有する制御装置１０等を備える。 As shown in the partial vertical sectional view of FIG. 1, the plan view of FIG. 2, and the main part enlarged vertical sectional view of FIG. 3, the metal detection device 1 according to the embodiment of the present invention includes a housing 1 </ b> A, ceramic ( (Nonmagnetic material) cylindrical body 2, detection coil 3 disposed radially outward of the cylindrical body 2, hopper 4 positioned above the cylindrical body 2 into which an object to be sorted (not shown) is placed, cylindrical body 2, the connecting pipe 5 provided between the upper end of the hopper 4 and the lower end of the hopper 4, the lead pipe 6 provided below the cylindrical body 2, the sorting damper 7 provided below the lead pipe 6, and the sorting damper 7. A swing drive device 8 that swings around a swing shaft 8A, a discharge chute 9 that discharges the object to be sorted including foreign metal, and an oscillation means and a target that oscillate by applying a high-frequency current to the detection coil 3. When the metal foreign matter in the selection passes through the internal space S of the cylindrical body 2 Detecting means for detecting a change in impedance of the coil 3 output, and a control device 10 or the like having a drive control means of the rocking mechanism 8.

そして、制御装置１０の発振手段により検出コイル３に高周波電流を与えて発振させた状態で、ホッパー４に投入された被選別物が重力により落下して円筒体２の内部空間Ｓを通過し、被選別物内の金属異物が内部空間Ｓを通過する際における検出コイル３のインピーダンス変化を制御装置１０の検出手段で検出することにより金属異物を検出する。このようにして金属異物を検出した際には、制御装置１０の駆動制御手段により揺動駆動装置８を駆動して揺動軸８Ａまわりに選別ダンパー７を揺動させることにより、金属異物が入った被選別物を排出シュート９から機外へ排出するので、金属異物が入った被選別物は下方の次工程へ流れない。 Then, in a state where a high frequency current is applied to the detection coil 3 by the oscillating means of the control device 10 and the object to be sorted dropped into the hopper 4 by gravity and passes through the internal space S of the cylindrical body 2. The metallic foreign matter is detected by detecting the impedance change of the detection coil 3 when the metallic foreign matter in the object to be sorted passes through the internal space S by the detecting means of the control device 10. When the metal foreign object is detected in this way, the metal drive is performed by driving the swing driving device 8 by the drive control means of the control device 10 to swing the selection damper 7 around the swing shaft 8A. Since the object to be sorted is discharged from the discharge chute 9 to the outside of the machine, the object to be sorted containing metal foreign matters does not flow to the next process below.

また、図３に示すように、連結管５は下方に縮径する（上方よりも下方の内径が小さい）テーパー管である。
さらに、円筒体２の外周面には全周にわたる凹溝２Ａが形成されており、凹溝２Ａ内に検出コイル３の内周面（内面）３Ａが配置される。 As shown in FIG. 3, the connecting pipe 5 is a tapered pipe that is reduced in diameter downward (the inner diameter below is smaller than above).
Further, a concave groove 2A is formed on the outer peripheral surface of the cylindrical body 2 over the entire circumference, and an inner peripheral surface (inner surface) 3A of the detection coil 3 is disposed in the concave groove 2A.

次に、検出コイル３までの落差（検出コイル３を通過する際の落下速度）による、制御装置１０の検出手段により検出コイル３のインピーダンス変化を検出した際の電圧であるセンサ検出電圧の変化を見るために行った実験例について説明する。 Next, the change in the sensor detection voltage, which is the voltage when the detection means of the control device 10 detects the impedance change of the detection coil 3 due to the drop to the detection coil 3 (falling speed when passing through the detection coil 3), is detected. An experimental example performed for viewing will be described.

図４のグラフは、直径０．２ｍｍのタングステンカーバイド（ＷＣ）のテストピースを自由落下させた実験例を、図５のグラフは、直径０．３ｍｍのステンレス鋼（ＳＵＳ３０４）のテストピースを自由落下させた実験例を示している。
また、図４（ａ）及び図５（ａ）は、検出コイル３までの落差によるセンサ検出電圧の変化を示すグラフであり、図４（ｂ）及び図５（ｂ）は、検出コイル３を通過する際の落下速度によるセンサ検出電圧の変化を示すグラフである。なお、「落下速度（ｍｍ／ｓ）」は、空気抵抗を考慮せずに落差と重力加速度から算出した理論値である。また、「センサ検出電圧（Ｖ）」は５回測定した値の平均値である。 The graph of FIG. 4 shows an experimental example in which a tungsten carbide (WC) test piece having a diameter of 0.2 mm is freely dropped, and the graph of FIG. 5 is a free fall of a test piece of stainless steel (SUS304) having a diameter of 0.3 mm. An experimental example is shown.
4A and 5A are graphs showing changes in the sensor detection voltage due to a drop to the detection coil 3, and FIGS. 4B and 5B show the detection coil 3. As shown in FIG. It is a graph which shows the change of the sensor detection voltage by the fall speed at the time of passing. The “falling speed (mm / s)” is a theoretical value calculated from the drop and the gravitational acceleration without considering the air resistance. The “sensor detection voltage (V)” is an average value of values measured five times.

図４及び図５の実験例から、検出コイル３を通過する際の速度が速いほどセンサ検出電圧が高くなり、特に小さい落差において落差変化によるセンサ検出電圧の変化が大きく、落差が５０ｍｍ（連結管５が無い場合に相当）のセンサ検出電圧の値に対する落差が１００ｍｍ（図３に示す連結管５の長さＬが５０ｍｍの場合に相当）のセンサ検出電圧の値は、約１．３倍になっており、落差が５０ｍｍ（連結管５が無い場合に相当）のセンサ検出電圧の値に対する落差が１５０ｍｍ（図３に示す連結管５の長さＬが１００ｍｍの場合に相当）のセンサ検出電圧の値は、約１．５倍になっている。
そこで、本発明では、図３に示す連結管５の長さＬを５０ｍｍ以上とし、すなわち連結管５の上端（ホッパー４の下端部）から検出コイル３までの高さ方向距離Ｈを１００ｍｍ以上としている。 4 and 5, the sensor detection voltage becomes higher as the speed when passing through the detection coil 3 is higher, and the change in the sensor detection voltage due to the head change is large especially in a small head, and the head is 50 mm (connecting pipe). The value of the sensor detection voltage when the head is 100 mm (corresponding to the case where the length L of the connecting pipe 5 shown in FIG. 3 is 50 mm) is about 1.3 times. The sensor detection voltage with a drop of 150 mm (corresponding to the case where the length L of the connecting pipe 5 shown in FIG. 3 is 100 mm) with respect to the sensor detection voltage value of 50 mm (corresponding to the case without the connecting pipe 5). The value of is about 1.5 times.
Therefore, in the present invention, the length L of the connecting pipe 5 shown in FIG. 3 is set to 50 mm or more, that is, the height direction distance H from the upper end of the connecting pipe 5 (the lower end portion of the hopper 4) to the detection coil 3 is set to 100 mm or more. Yes.

次に、主に連結管５内における被選別物の流れの状況を見るために行った実験例について説明する。 Next, a description will be given of an example of an experiment conducted mainly to see the state of the flow of the object to be sorted in the connecting pipe 5.

図３に示す上口径（ホッパー４の下端内径）Ｄ１、下口径（連結管５の下端内径）Ｄ２、連結管５の長さＬ、連結管５の上端から検出コイル３までの高さ方向距離Ｈ（Ｈ＝Ｌ＋５０）を、実施例１及び２、並びに比較例１ないし３のように変えたものを試作し、被選別物である樹脂ペレットに直径０．２ｍｍのタングステンカーバイド（ＷＣ）を入れたテストピースを混ぜて流して評価を行った結果を表１に示す。
（１）実施例１：Ｄ１＝３０ｍｍ，Ｄ２＝１９ｍｍ，Ｌ＝２００ｍｍ，Ｈ＝２５０ｍｍ。
（２）実施例２：Ｄ１＝３０ｍｍ，Ｄ２＝１９ｍｍ，Ｌ＝３００ｍｍ，Ｈ＝３５０ｍｍ。
（３）比較例１：Ｄ１＝４０ｍｍ，Ｄ２＝１９ｍｍ，Ｌ＝６０ｍｍ，Ｈ＝１１０ｍｍ。
（４）比較例２：Ｄ１＝４０ｍｍ，Ｄ２＝１９ｍｍ，Ｌ＝２００ｍｍ，Ｈ＝２５０ｍｍ。
（５）比較例３：Ｄ１＝３０ｍｍ，Ｄ２＝１９ｍｍ，Ｌ＝１２０ｍｍ，Ｈ＝１７０ｍｍ。 The upper diameter (the lower end inner diameter of the hopper 4) D1, the lower diameter (the lower end inner diameter of the connecting pipe 5) D2, the length L of the connecting pipe 5, and the distance in the height direction from the upper end of the connecting pipe 5 to the detection coil 3 shown in FIG. Samples in which H (H = L + 50) was changed as in Examples 1 and 2 and Comparative Examples 1 to 3 were made, and tungsten carbide (WC) having a diameter of 0.2 mm was placed in resin pellets to be selected. Table 1 shows the results of evaluation by mixing and flowing test pieces.
(1) Example 1: D1 = 30 mm, D2 = 19 mm, L = 200 mm, H = 250 mm.
(2) Example 2: D1 = 30 mm, D2 = 19 mm, L = 300 mm, H = 350 mm.
(3) Comparative Example 1: D1 = 40 mm, D2 = 19 mm, L = 60 mm, H = 110 mm.
(4) Comparative Example 2: D1 = 40 mm, D2 = 19 mm, L = 200 mm, H = 250 mm.
(5) Comparative Example 3: D1 = 30 mm, D2 = 19 mm, L = 120 mm, H = 170 mm.

評価項目は、検出コイル３を通過する際の落下速度である「落下速度（ｍｍ／ｓ）」、被選別物である樹脂ペレットに直径０．２ｍｍのタングステンカーバイド（ＷＣ）を入れたテストピースを混ぜて流した場合の前記センサ検出電圧である「検出電圧（Ｖ）」、２ｋｇの樹脂ペレットが流れるのに要する時間である「２ｋｇ処理時間（ｓ）」、及び連結管５内における樹脂ペレットの状態が、密に詰まった状態（「密」）で落下しているか、密に詰まっておらず粗い状態（「粗」）で落下しているかを観察して示した「連結管内粗密状態」とした。
なお、「落下速度（ｍｍ／ｓ）」は検出コイル３から上方へ２５ｍｍの位置から下方へ２５ｍｍの位置までの５０ｍｍの間隔を通過した時間Ｔ（ｓ）を計測して５０／Ｔから求めており、３回測定した値の平均値である。また、「検出電圧（Ｖ）」は、前記図４及び図５の「センサ検出電圧（Ｖ）」と同様に５回測定した平均値である。 The evaluation items are “falling speed (mm / s)” which is a falling speed when passing through the detection coil 3, and a test piece in which tungsten carbide (WC) having a diameter of 0.2 mm is put in a resin pellet which is an object to be selected. “Detection voltage (V)”, which is the sensor detection voltage when mixed and flowed, “2 kg processing time (s)”, which is the time required for 2 kg of resin pellets to flow, and resin pellets in the connecting pipe 5 “Dense state in the connecting pipe” that shows whether the state is falling in a tightly packed state (“dense”) or whether it is falling in a rough state (“rough”) without being densely packed did.
The “falling speed (mm / s)” is obtained from 50 / T by measuring a time T (s) passing through a 50 mm interval from a position 25 mm upward from the detection coil 3 to a position 25 mm downward. It is the average of the values measured three times. The “detection voltage (V)” is an average value measured five times in the same manner as the “sensor detection voltage (V)” in FIGS.

表１の結果から、「連結管内粗密状態」が「密」である比較例１ないし３は、「落下速度」及び「検出速度」が小さいとともに、「２ｋｇ処理時間」が大きく、それらに対して「連結管内粗密状態」が「粗」である実施例１及び２は、「落下速度」及び「検出速度」が大きいとともに、「２ｋｇ処理時間」が小さいことが分かる。
ここで、比較例１及び２は、上口径Ｄ１が大きいことから、連結管５内に流れ込む樹脂ペレットの量が多過ぎるため、樹脂ペレットが連結管５内を密に詰まった状態（「密」）で落下している。
また、比較例３は、連結管５の長さＬが小さいことから、連結管５内に入った樹脂ペレットを加速する距離が小さいため、樹脂ペレットが連結管５内を密に詰まった状態（「密」）で落下している。 From the results of Table 1, in Comparative Examples 1 to 3 in which the “in-condensed state in the connecting pipe” is “dense”, the “falling speed” and the “detection speed” are small, and the “2 kg processing time” is large. It can be seen that in Examples 1 and 2 in which the “in-condensed pipe density state” is “coarse”, the “falling speed” and the “detection speed” are large and the “2 kg processing time” is small.
Here, in Comparative Examples 1 and 2, since the upper diameter D1 is large, the amount of resin pellets flowing into the connecting pipe 5 is too large, so that the resin pellets are tightly packed in the connecting pipe 5 (“dense”). ).
Further, in Comparative Example 3, since the length L of the connecting pipe 5 is small, the distance for accelerating the resin pellet that has entered the connecting pipe 5 is small, so that the resin pellet is tightly packed in the connecting pipe 5 ( "Dense") is falling.

そこで、本発明では、重力によりホッパー４から連結管５内に入った被選別物が連結管５内で密に詰まらずに粗い状態で落下（自由落下（自然落下）又はそれに近い状態で落下）するように連結管５の長さＬ及び口径Ｄ１，Ｄ２を定めている。
なお、表1の実施例１及び２のように、被選別物が連結管５内を前記粗い状態で流れる条件のときは、連結管５を無くしてホッパー４だけで被選別物を流しても処理時間（例えば表１の「２ｋｇ処理時間」）は同じになる。よって、長さ及び口径を任意に定めた連結管５を取り付けて被選別物を流した場合とホッパー４だけで被選別物を流した場合とで、所定量の被選別物を流した場合の処理時間が同じになることを確認すれば、重力によりホッパー４から連結管５内に入った被選別物が連結管５内で密に詰まらずに粗い状態で落下するよう定められた連結管５の形状であることを確認できる。 Therefore, in the present invention, the object to be sorted that has entered the connecting pipe 5 from the hopper 4 due to gravity falls in a rough state without being clogged tightly in the connecting pipe 5 (free fall (natural fall) or close to it). Thus, the length L and the diameters D1 and D2 of the connecting pipe 5 are determined.
In addition, as in Examples 1 and 2 of Table 1, when the material to be sorted flows in the connecting pipe 5 in the rough state, the material to be sorted can be flowed only by the hopper 4 without the connecting tube 5. The processing time (for example, “2 kg processing time” in Table 1) is the same. Therefore, in the case where the sorting object is made to flow by attaching the connecting pipe 5 having an arbitrarily defined length and diameter and the case where the sorting object is made to flow only by the hopper 4 If it is confirmed that the processing time is the same, the connection pipe 5 that is determined so that the objects to be sorted that have entered into the connection pipe 5 from the hopper 4 due to gravity fall in a rough state without being clogged tightly in the connection pipe 5. Can be confirmed.

以上のような構成の本発明の金属検出装置の構成によれば、重力によりホッパー４から連結管５内に入った被選別物が連結管５内で密に詰まらずに粗い状態で落下（自由落下（自然落下）又はそれに近い状態で落下）するように連結管５の長さＬ及び口径Ｄ１，Ｄ２が定められているので、被選別物が連結管５内で密に詰まって落下速度が低下することがない。
その上、連結管５の上端から検出コイル３までの高さ方向距離Ｈが１００ｍｍ以上であるので、被選別物が重力により加速されて落下速度が上昇した状態で検出コイル３を通過する。
よって、簡素な構成により製造コストの上昇を抑制しながら、被選別物に混入した金属異物の検出精度を向上できるとともに、処理能力を向上できる。 According to the configuration of the metal detection device of the present invention having the above-described configuration, an object to be sorted that has entered into the connecting pipe 5 from the hopper 4 due to gravity falls in a rough state without being clogged tightly in the connecting pipe 5 (free Since the length L and the diameters D1 and D2 of the connecting pipe 5 are determined so as to fall (spontaneous fall) or close to it), the to-be-sorted objects are closely packed in the connecting pipe 5 and the dropping speed is increased. There is no decline.
In addition, since the height direction distance H from the upper end of the connecting pipe 5 to the detection coil 3 is 100 mm or more, the object to be sorted passes through the detection coil 3 in a state where the fall speed is increased due to acceleration by gravity.
Therefore, while suppressing an increase in manufacturing cost with a simple configuration, it is possible to improve the detection accuracy of the metal foreign matter mixed in the object to be sorted and improve the processing capability.

また、下方位置の被選別物の方が重力により加速されて高速であることから、連結管５で被選別物が密に詰まらないようにする断面積を小さくできるので、図１及び図３のように連結管５を下方に縮径するテーパー管にすることができ、連結管５を前記テーパー管にすることにより、連結管５の下方に位置する円筒体２及び検出コイル３を小径化できるため、検出感度が向上する。
さらに、図３のように円筒体２の外周面に全周にわたる凹溝２Ａを形成し、凹溝２Ａ内に検出コイル３の内周面３Ａを配置することにより、検出コイル３をさらに小径化できるので、検出感度をさらに向上できる。 In addition, since the object to be sorted in the lower position is accelerated by gravity and has a higher speed, the cross-sectional area that prevents the object to be sorted from being densely blocked by the connecting pipe 5 can be reduced. Thus, the connecting tube 5 can be made into a tapered tube whose diameter is reduced downward, and the cylindrical body 2 and the detection coil 3 located below the connecting tube 5 can be reduced in diameter by using the connecting tube 5 as the tapered tube. Therefore, the detection sensitivity is improved.
Further, as shown in FIG. 3, the outer circumferential surface of the cylindrical body 2 is formed with a concave groove 2A over the entire circumference, and the inner circumferential surface 3A of the detection coil 3 is arranged in the concave groove 2A, thereby further reducing the diameter of the detection coil 3. Therefore, the detection sensitivity can be further improved.

以上のような連結管５の構成において、検出感度をさらに向上させるために、図３に示す下口径Ｄ２を、例えば表１に示す１９ｍｍからさらに小さくし（例えば、Ｄ２＝１０ｍｍ程度）、検出コイル３の内周面３Ａの直径をより小さくする場合において、処理能力を向上させるためには上口径Ｄ１をなるべく大きくする必要がある。
よって、本発明の実施の形態に係る金属検出装置１は、前記のとおり、重力によりホッパー４から連結管５内に入った被選別物が連結管５内で密に詰まらずに粗い状態で落下するように連結管５の長さＬ及び口径Ｄ１，Ｄ２が定めるものであるが、検出感度をさらに向上させるために下口径Ｄ２を小さくするとともに、処理能力を向上させるために上口径Ｄ１をなるべく大きくした金属検出装置１を用いて、様々なサイズの被選別物に混入した金属異物の検出を行う場合、大きさが比較的大きい被選別物（例えば、数ｍｍ以上の大きさの樹脂ペレット）をホッパー４から流すと、連結管５内の比較的下方位置で被選別物が詰まりやすくなる。 In the configuration of the connecting pipe 5 as described above, in order to further improve the detection sensitivity, the lower diameter D2 shown in FIG. 3 is further reduced from, for example, 19 mm shown in Table 1 (for example, D2 = about 10 mm) to detect the detection coil. In the case where the diameter of the inner peripheral surface 3A of 3 is made smaller, it is necessary to make the upper diameter D1 as large as possible in order to improve the processing capability.
Therefore, as described above, the metal detection device 1 according to the embodiment of the present invention falls in a rough state without the objects to be sorted entering the connection pipe 5 from the hopper 4 due to gravity being tightly packed in the connection pipe 5. As described above, the length L and the diameters D1 and D2 of the connecting pipe 5 are determined. In order to further improve the detection sensitivity, the lower diameter D2 is reduced, and the upper diameter D1 is set as much as possible to improve the processing capability. When detecting metal foreign matter mixed in various sizes of objects to be detected using the enlarged metal detector 1, the objects to be selected are relatively large (for example, resin pellets having a size of several mm or more). When the hopper 4 is flown from the hopper 4, the objects to be sorted are easily clogged at a relatively lower position in the connecting pipe 5.

以上の検討結果から、金属検出装置１において、被選別物の詰まりに対する策を講じておくことが好ましい。
このような観点から検討を行った点について、先ず、下方に縮径するテーパー管である連結管５の形状の変形例を示す。 From the above examination results, it is preferable to take measures against clogging of objects to be sorted in the metal detection device 1.
Regarding the points studied from this point of view, first, a modification of the shape of the connecting pipe 5 which is a tapered pipe whose diameter is reduced downward will be described.

図６の落差による自由落下の落下速度の変化を示すグラフに示すように、連結管５の上端部から落下する被選別物の落差が小さい範囲では、被選別物の落下速度の変化が大きいことが分かる。
また、連結管５の上端部から落下する被選別物の流量は、（落下速度）×（断面積）である。
よって、連結管５の上端部から落下する被選別物の落差が小さい範囲（連結管５の上部）では、断面積の変化率、すなわち下方に縮径する比率を大きくできる。 As shown in the graph of the change in the falling speed of free fall due to the drop in FIG. 6, the change in the falling speed of the object to be sorted is large in the range where the drop of the object to be sorted falling from the upper end of the connecting pipe 5 is small. I understand.
Further, the flow rate of the object to be sorted falling from the upper end of the connecting pipe 5 is (falling speed) × (cross-sectional area).
Therefore, in the range where the drop of the sorting object falling from the upper end portion of the connecting pipe 5 is small (upper part of the connecting pipe 5), the change rate of the cross-sectional area, that is, the ratio of reducing the diameter downward can be increased.

このような知見から、連結管５の形状は、図３の要部拡大縦断面図のような下方に縮径する比率が均一な円錐管状のものに限定されるものではなく、図７（ａ）の要部拡大縦断面図のような２段円錐管状であり、下方に縮径する比率が上段円錐管５Ａよりも下段円錐管５Ｂの方が小さいものであってもよく、図７（ｂ）の要部拡大縦断面図のような前記比率が下方へ行くに従って漸減するものであってもよい。 From such knowledge, the shape of the connecting pipe 5 is not limited to a conical tubular shape with a uniform ratio of reducing the diameter downward as shown in the enlarged vertical sectional view of the main part of FIG. 7), the lower-stage conical tube 5B may be smaller in the lower-cone tube 5B than the upper-cone tube 5A. ), The ratio may gradually decrease as it goes downward.

図７（ａ）及び図７（ｂ）のような連結管５の形状にすることにより、連結管５の上下方向の中間部分の内径が、図３のような下方に縮径する比率が均一な円錐管状の連結管５よりも小さくなる。
よって、万が一、被選別物の大きさ等による連結管５内下方での詰まりや連結管５の下流側で流れが堰き止められ、連結管５内で被選別物が詰まった場合において、図７（ａ）及び図７（ｂ）のような形状の連結管５を用いることにより、連結管５の上下方向の中間部分に滞留する被選別物の量が少なくなる。それにより、連結管５内での詰まりや下流側等での流れの堰き止めが解消され、被選別物の流れが再開する際、連結管５内の被選別物は下方から粗になり落下し始めるが、被選別物の滞留量が少ないことから早く滞留量が少なくなる。また、同時に上部のホッパー４から被選別物が連結管５に流入してくるが、このような連結管５の形状により、連結管５に密で低速に流入する量より粗で自由落下速度で排出する量の方が多く、密と粗の境界が次第に上方に移動し連結管５内の被選別物の流れは全て粗状態になり速い落下速度（自由落下速度）に復帰しやすくなるので、使い勝手を向上できる。 By making the shape of the connecting pipe 5 as shown in FIGS. 7 (a) and 7 (b), the inner diameter of the intermediate portion in the vertical direction of the connecting pipe 5 is uniform in the downward direction as shown in FIG. It becomes smaller than the conical tubular connecting pipe 5.
Therefore, in the unlikely event that clogging occurs in the lower part of the connecting pipe 5 due to the size of the object to be sorted or the flow is blocked on the downstream side of the connecting pipe 5, and the object to be sorted is clogged in the connecting pipe 5, FIG. By using the connecting pipe 5 having a shape as shown in FIG. 7A and FIG. 7B, the amount of the object to be sorted that stays in the middle portion of the connecting pipe 5 in the vertical direction is reduced. As a result, clogging in the connecting pipe 5 and damming of the flow on the downstream side are eliminated, and when the flow of the material to be sorted resumes, the material to be sorted in the connecting pipe 5 becomes rough and falls from below. At first, the retention amount decreases quickly because the retention amount of the objects to be sorted is small. At the same time, an object to be sorted flows from the upper hopper 4 into the connecting pipe 5, but due to the shape of the connecting pipe 5, the free fall speed is coarser than the amount flowing into the connecting pipe 5 at a low speed. Since the amount to be discharged is larger, the dense and coarse boundary gradually moves upward, and the flow of the objects to be sorted in the connecting pipe 5 is all in a rough state, and it is easy to return to a fast fall speed (free fall speed). Usability can be improved.

次に、被選別物の詰まりに対する策として、詰まりを発生しにくくする構成について説明する。
図８の模式図に示す金属検出装置１は、連結管５及び円筒体２を傾斜させた状態で配置したものであり、連結管５及び円筒体２を１５°傾斜させた例を示している。なお、連結管５及び円筒体２の傾斜角度は、例えば１０〜３０°程度にすればよい。 Next, a configuration that makes it difficult to generate clogging will be described as a measure against clogging of objects to be selected.
The metal detection device 1 shown in the schematic diagram of FIG. 8 is arranged with the connecting pipe 5 and the cylindrical body 2 inclined, and shows an example in which the connecting pipe 5 and the cylindrical body 2 are inclined by 15 °. . In addition, what is necessary is just to make the inclination-angle of the connecting pipe 5 and the cylindrical body 2 into about 10-30 degrees, for example.

また、図８の例は、連結管５の長さを長くして連結管５の下口径及び円筒体２の内径及び検出コイル３の内径をなるべく小さくした構成（例えば、連結管５の長さは４００ｍｍ程度、ホッパー４の下端内径は２０ｍｍ程度、円筒体２の内径は１０ｍｍ程度）を示している。
このように連結管５の長さを長くすることにより落差が大きくなって被選別物の落下速度が非常に大きくなることから検出電圧が高くなるとともに、検出コイル３の内径をなるべく小さくすることにより検出感度が高まるので、被選別物に混入した金属異物の検出精度が非常に高くなる。
ここで、図８に示すように、連結管５だけではなく円筒体２も傾斜させている（本実施の形態ではリード管６の上部も傾斜させている）ので、落下速度が非常に大きい被選別物をスムーズに流すことができる。 In the example of FIG. 8, the length of the connecting pipe 5 is increased so that the lower diameter of the connecting pipe 5, the inner diameter of the cylindrical body 2, and the inner diameter of the detection coil 3 are reduced as much as possible (for example, the length of the connecting pipe 5). Is about 400 mm, the inner diameter of the lower end of the hopper 4 is about 20 mm, and the inner diameter of the cylindrical body 2 is about 10 mm).
By increasing the length of the connecting pipe 5 in this way, the drop becomes large and the falling speed of the object to be sorted becomes very large, so that the detection voltage increases and the inner diameter of the detection coil 3 is made as small as possible. Since the detection sensitivity increases, the detection accuracy of the metal foreign matter mixed in the object to be sorted becomes very high.
Here, as shown in FIG. 8, not only the connecting pipe 5 but also the cylindrical body 2 is inclined (in this embodiment, the upper part of the reed pipe 6 is also inclined), so that the fall speed is very high. The selected items can flow smoothly.

図８のように連結管５の長さを長くして連結管５の下口径及び円筒体２の内径及び検出コイル３の内径をなるべく小さくする構成例において、連結管５及び円筒体２を鉛直に配置した場合には、被選別物の流量（（落下速度）×（断面積））が大きく、被選別物が落下するにしたがって落下速度は速くなるが、連結管５のテーパー形状により連結管５内でほぼ均等に圧力がかかることになる。よって、前記のとおり被選別物の大きさ等によっては詰まりが発生しやすくなる。
それに対して図８の構成例のように連結管５及び円筒体２を傾斜させた状態で配置することにより、連結管５及び円筒体２内を落下する被選別物が重力の影響で管内の下方へ寄って流れ、連結管５及び円筒体２内の上側部分に隙間ができることから、詰まりが発生しにくくなるので、使い勝手をさらに向上できる。
なお、このような連結管５及び円筒体２を傾斜させた状態で配置する構成は、連結管５が細くて長い場合に特に有効である。 As shown in FIG. 8, in the configuration example in which the length of the connecting pipe 5 is increased so that the lower diameter of the connecting pipe 5 and the inner diameter of the cylindrical body 2 and the inner diameter of the detection coil 3 are reduced as much as possible. The flow rate of the object to be sorted ((falling speed) × (cross-sectional area)) is large, and the falling speed increases as the material to be sorted drops. The pressure is applied almost evenly within 5. Therefore, as described above, clogging is likely to occur depending on the size of the object to be sorted.
On the other hand, by arranging the connecting pipe 5 and the cylindrical body 2 in an inclined state as in the configuration example of FIG. 8, an object to be sorted falling in the connecting pipe 5 and the cylindrical body 2 is affected by gravity. Since the gas flows downward and a gap is formed in the upper portion of the connecting pipe 5 and the cylindrical body 2, clogging is less likely to occur, so that the usability can be further improved.
Such a configuration in which the connecting pipe 5 and the cylindrical body 2 are disposed in an inclined state is particularly effective when the connecting pipe 5 is thin and long.

次に、被選別物の詰まりに対する策として、詰まりを解消する方法について説明する。
図１及び図８に示す構成例において、被選別物の大きさ等によって被選別物が連結管５内で詰まってしまった場合には、図８に示すようにホッパー４の出口に設けたシャッター１１を閉じて連結管５内への被選別物の進入を遮断し、例えば振動発生装置又は衝撃発生装置である詰まり解消装置１２を駆動して連結管５を振動させて詰まりを取り除いた後、シャッター１１を開ければよい。
このように詰まりを解消する手段であるシャッター１１及び詰まり解消装置１２を設けておくことにより、詰まりが発生した際に迅速に復旧できるといともに、万が一詰まりが発生した際に詰まりを解消できことから、余裕を見ることなく被選別物の流量を増やして処理能力を向上できるので、使い勝手を一層向上できる。
また、図８のように連結管５及び円筒体２を傾斜させた状態で配置する構成において、連結管５を、図７（ａ）のような２段円錐管状のもの、又は図７（ｂ）のような下方に縮径する比率が下方へ行くに従って漸減するものとしてもよい。図７（ａ）及び図７（ｂ）のような連結管５の形状にすることにより、前記のとおり詰まりを解消した後の流れの再開がスムーズになるので、使い勝手をより一層向上できる。 Next, a method for eliminating clogging will be described as a measure against clogging of objects to be selected.
In the configuration example shown in FIG. 1 and FIG. 8, when the object to be selected is clogged in the connecting pipe 5 due to the size of the object to be selected, the shutter provided at the outlet of the hopper 4 as shown in FIG. 11 is closed to block the entry of the object to be sorted into the connecting pipe 5, for example, the clogging device 12, which is a vibration generator or an impact generator, is driven to vibrate the connecting pipe 5 to remove the clogging, The shutter 11 may be opened.
By providing the shutter 11 and the clog eliminating device 12 as means for eliminating clogging in this way, it is possible to quickly recover when clogging occurs and to eliminate clogging when clogging occurs. Since the processing capacity can be improved by increasing the flow rate of the object to be sorted without a margin, the usability can be further improved.
Further, in the configuration in which the connecting pipe 5 and the cylindrical body 2 are disposed in an inclined state as shown in FIG. 8, the connecting pipe 5 is a two-stage conical tube as shown in FIG. 7A, or FIG. The ratio of decreasing diameter as in () may be gradually decreased as it goes downward. By making the shape of the connecting pipe 5 as shown in FIGS. 7A and 7B, the flow can be restarted smoothly after the clogging is eliminated as described above, and the usability can be further improved.

１金属検出装置
１Ａ筐体
２円筒体
２Ａ凹溝
３検出コイル
３Ａ内周面
４ホッパー
５連結管
５Ａ上段円錐管
５Ｂ下段円錐管
６リード管
７選別ダンパー
８揺動駆動装置
８Ａ揺動軸
９排出シュート
１０制御装置
１１シャッター
１２詰まり解消装置
Ｄ１上口径
Ｄ２下口径
Ｈ連結管の上端から検出コイルまでの高さ方向距離
Ｌ連結管の長さ
Ｓ内部空間 DESCRIPTION OF SYMBOLS 1 Metal detection apparatus 1A Case 2 Cylindrical body 2A Groove 3 Detection coil 3A Inner peripheral surface 4 Hopper 5 Connection pipe 5A Upper stage conical pipe 5B Lower stage conical pipe 6 Lead pipe 7 Sorting damper 8 Swing drive 8A Swing shaft 9 Discharge Chute 10 Control device 11 Shutter 12 Clogging elimination device D1 Upper diameter D2 Lower diameter H Height direction distance L from the upper end of the connection pipe to the detection coil Length S of the connection pipe Internal space

Claims

非磁性体製の円筒体の径方向外方に検出コイルを配設し、前記検出コイルに高周波電流を与えて発振させた状態で、ホッパーに投入された被選別物が重力により落下して前記円筒体の内部空間を通過し、前記被選別物内の金属異物が前記内部空間を通過する際における前記検出コイルのインピーダンス変化を検出することにより前記金属異物を検出する金属検出装置であって、
前記円筒体の上端部と前記ホッパーの下端部との間に連結管を設け、重力により前記ホッパーから前記連結管内に入った前記被選別物が前記連結管内で密に詰まらずに粗い状態で落下するように前記連結管の長さ及び口径を定めるとともに、前記連結管の上端から前記検出コイルまでの高さ方向距離を１００ｍｍ以上としてなることを特徴とする金属検出装置。 A detection coil is disposed outside the cylindrical body made of a non-magnetic material, and a high-frequency current is applied to the detection coil to oscillate the object to be sorted dropped into the hopper due to gravity. A metal detection device that detects the metal foreign object by detecting an impedance change of the detection coil when the metal foreign object in the object to be sorted passes through the internal space and passes through the internal space.
A connecting pipe is provided between the upper end of the cylindrical body and the lower end of the hopper, and the to-be-sorted material that has entered the connecting pipe from the hopper by gravity falls in a rough state without being clogged tightly in the connecting pipe. Thus, the length and the diameter of the connecting pipe are determined, and the height direction distance from the upper end of the connecting pipe to the detection coil is set to 100 mm or more.

前記連結管が下方に縮径するテーパー管である請求項１記載の金属検出装置。 The metal detecting device according to claim 1, wherein the connecting pipe is a tapered pipe having a diameter reduced downward.

前記テーパー管が２段円錐管状であり、下方に縮径する比率が上段の円錐管よりも下段の円錐管の方が小さいもの、
又は前記テーパー管の下方に縮径する比率が下方へ行くに従って漸減するものである請求項２記載の金属検出装置。 The tapered tube is a two-stage conical tube, and the lower cone tube has a smaller ratio of diameter reduction downward than the upper cone tube,
3. The metal detection device according to claim 2, wherein the ratio of diameter reduction to the lower side of the taper pipe gradually decreases as going downward.

前記連結管及び前記円筒体を傾斜させた状態で配置してなる請求項１〜３の何れか１項に記載の金属検出装置。 The metal detection apparatus according to claim 1, wherein the connecting pipe and the cylindrical body are arranged in an inclined state.

前記円筒体の外周面に全周にわたる凹溝を形成し、前記凹溝内に前記検出コイルの内周面を配置してなる請求項１〜４の何れか１項に記載の金属検出装置。 5. The metal detection device according to claim 1, wherein a concave groove is formed on an outer peripheral surface of the cylindrical body over the entire circumference, and an inner peripheral surface of the detection coil is disposed in the concave groove.