JP4460199B2

JP4460199B2 - Metal detector and method for adjusting balance of metal detector

Info

Publication number: JP4460199B2
Application number: JP2001279900A
Authority: JP
Inventors: 誠至山岸; 紀彦長岡; 聡三谷; 茂久保寺
Original assignee: アンリツ産機システム株式会社
Priority date: 2001-09-14
Filing date: 2001-09-14
Publication date: 2010-05-12
Anticipated expiration: 2021-09-14
Also published as: JP2003084072A

Description

【０００１】
【発明の属する技術分野】
本発明は、被検査体に混入した金属物を検出する金属検出機に関し、特に磁束のバランスを調整する調整機構を備えた金属検出機に関するものである。
【０００２】
【従来の技術】
金属検出機は、被検査体に混入された金属が検査磁界に与える変化を検出することによって、被検査体に金属が混入しているか否かを判別している。
図４は、金属検出機における検出ヘッドの検出原理を示す図である。図４に示すように、従来では、例えば中央の送信コイル３１の前後に受信コイル３２，３３を配置して、被検査体Ｗの通過方向（図４中Ａ方向）に対して平行な磁力線を生成するヘッドコイル配置をした同軸型の検出ヘッド３０が用いられている。
【０００３】
上記検出ヘッド３０では、各コイル３１，３２，３３の内側に連続する検査空間Ｓ内において、中央の送信コイル３１の交番磁界による磁束に交わる受信コイル３２，３３にそれぞれ位相が逆の誘起電圧Ｖ１，Ｖ２を発生させる。各受信コイル３２，３３は、送信コイル３１に対して等しい距離に配置され、検査空間Ｓから被検査体Ｗが遠い位置にある非検出状態では誘起電圧Ｖ１，Ｖ２の大きさが等しく差が０となる。
【０００４】
例えば、金属Ｍが混入した被検査体Ｗが、図４中Ａ方向に進行して手前の受信コイル３２内に移動すると、受信コイル３２内の磁束密度が増し、逆に受信コイル３３内の磁束密度が減少する。このため、受信コイル３２の誘起電圧Ｖ１は、受信コイル３３の誘起電圧Ｖ２よりも大きくなる。次いで、進行した被検査体Ｗが受信コイル３３内まで移動すると、受信コイル３２内よりも受信コイル３３内の磁束密度の方が大きくなるため、誘起電圧Ｖ１より誘起電圧Ｖ２の方が大きくなる。このようにして、検出ヘッド３０から出力される誘起電圧Ｖ１，Ｖ２の差の変化（磁界の揺らぎ）に基づいて、検査空間Ｓ内を通過した被検査体Ｗに金属Ｍが混入しているか否かを判定することができる。
【０００５】
一般に、上記検出ヘッド３０は、検査空間Ｓ内に搬送コンベア（不図示）が貫通するように配置されており、図５に示す略ロ字型の筐体３５内部に収容されている。筐体３５は、金属（例えばアルミ合金やステンレス鋼）などの磁気シールドの材質で形成されている。そして、搬送コンベアによって被検査体Ｗを搬送して検査空間Ｓ内を通過させる。
【０００６】
上記の構成において、製造・組立時の誤差などにより、非検出状態にて受信コイル３２，３３における各誘起電圧Ｖ１，Ｖ２の差が０とならず、誘起電圧の平衡が狂うことがある。このため、金属Ｍの検出が正確に行えなくなってしまう。そこで、バランス調整が必要となる。従来でのバランス調整は、図５に示すように、筐体３５の検査空間Ｓの部位に磁性体および非磁性体である金属板３６を貼ったり、外側部に磁性体および非磁性体である金属棒３７（例えばネジ）を差し込むことでバランス調整を行っていた。金属板３６での調整は、筐体３５に対する貼り付け位置を変化させて誘起電圧が平衡した位置にて固定する。金属棒３７での調整は、筐体３５に対する差し込み深さを変化させて誘起電圧が平衡した位置にて固定する。
【０００７】
【発明が解決しようとする課題】
ところで、上述した従来の金属検出機で用いられている同軸型の検出ヘッド３０では、例えば針形状や薄板形状の金属Ｍについて、上記形状の金属Ｍである磁性体が磁束に略直交する配置、あるいは上記形状の金属Ｍである非磁性体が磁束に平行な配置で被検査体Ｗに混入していた場合では、磁束の変化が少ないため誘起電圧Ｖ１，Ｖ２の差が小さく検出感度が落ちてしまう。すなわち、被検査体Ｗに混入している金属Ｍを検出できないおそれがある。
【０００８】
そこで、図６に示すように、検出ヘッド３０とは磁束の方向が直交する検出ヘッド４０を検出ヘッド３０と共に用いた二軸二組の金属検出機が考えられる。検出ヘッド４０は、図６に示すように、例えば検出ヘッド３０の上方に送信コイル４１を配置し、送信コイル４１に対向する検出ヘッド３０の下方に、併設した受信コイル４２，４３を配置して、被検査体Ｗの通過方向（図４中Ａ方向）に対して直交する磁力線を生成するヘッドコイル配置をした対向型とされている。検出ヘッド４０は、検査空間Ｓ内において送信コイル４１の交番磁界による磁束に交わる各送信コイル４２，４３にそれぞれ位相が逆の誘起電圧Ｖ３，Ｖ４を発生させる。各受信コイル４２，４３は、送信コイル４１に対して等しい距離に配置され、非検出状態では誘起電圧Ｖ３，Ｖ４の大きさが等しく差が０となる。
【０００９】
この金属検出機では、図６に示すように、検出ヘッド３０では左右方向の磁束を生じ、検出ヘッド４０では上下方向の磁束を生じる。そして、検出ヘッド３０の磁束に対して針形状や薄板形状の金属Ｍである磁性体が磁束に略直交する配置であっても、検出ヘッド４０側では、その磁束に対して平行な配置となるので、磁束の変化が多くなって誘起電圧Ｖ３，Ｖ４の差が大きく検出感度が良好となる。また、検出ヘッド３０の磁束に対して針形状や薄板形状の金属Ｍである非磁性体が磁束に平行な配置であっても、検出ヘッド４０側では、その磁束に対して直交する配置となるので、磁束の変化が多くなって誘起電圧Ｖ３，Ｖ４の差が大きく検出感度が良好となる。このように、検出ヘッド４０は検出ヘッド３０で検出し難い金属Ｍを良好に検出し、逆に検出ヘッド３０は検出ヘッド４０で検出し難い金属Ｍを良好に検出する。
【００１０】
しかしながら、上述した二軸二組の金属検出機は、上記バランス調整によって検出ヘッド３０の誘起電圧の平衡を得ようとしても、その影響で検出ヘッド４０での誘起電圧の平衡が得られなくなってしまう。逆に、上記バランス調整によって検出ヘッド４０の誘起電圧の平衡を得ようとした場合には、その影響で検出ヘッド３０での誘起電圧の平衡が得られなくなってしまう。このように、二軸二組の金属検出機では、双方の検出ヘッド３０，４０の誘起電圧の平衡を得ることが困難であるという問題が生じる。
【００１１】
そこで本発明は、上記課題を解消するために、二軸二組の各検出ヘッドをなす金属検出機にて、各検出ヘッドの誘起電圧の平衡の調整を容易に行うことができる金属検出機および金属検出機のバランス調整方法を提供することを目的としている。
【００１２】
【課題を解決するための手段】
上記目的を達成するため本発明による請求項１記載の金属検出機は、
被検査体Ｗが搬送される検査空間Ｓ内に直交する二軸の磁界を生成する各検出ヘッド３０，４０を共に有した金属検出機であって、
前記一方の検出ヘッド３０と前記他方の検出ヘッド４０のそれぞれの生成磁界が交わる共有領域Ｌ１（Ｌ１’）と、
前記一方の検出ヘッド３０あるいは前記他方の検出ヘッド４０の何れかの生成磁界が前記共有領域外Ｌ１（Ｌ１’）まで延びていて前記共有領域Ｌ１（Ｌ１’）と隣接している独立領域Ｌ２（Ｌ２’）と、
前記共有領域Ｌ１（Ｌ１’）に配されて前記一方の検出ヘッド３０あるいは前記他方の検出ヘッド４０の何れか一方の各受信コイル３２，３３（４２，４３）の誘起電圧の平衡を得る調整部５１（５２’）と、
前記独立領域Ｌ２（Ｌ２’）に配されて前記一方の検出ヘッド３０あるいは前記他方の検出ヘッド４０の何れか他方の各受信コイル４２，４３（３２，３３）の誘起電圧の平衡を得る調整部５２（５１’）と、
を備えたことを特徴とする。
【００１３】
請求項２記載の金属検出機は、請求項１記載の金属検出機において、
前記各調整部５１，５２（５１’，５２’）が、前記検査空間Ｓに関与しない部位に配置され、前記各調整部５１，５２（５１’，５２’）にかかる部位の前記共有領域Ｌ１（Ｌ１’）と前記独立領域Ｌ２（Ｌ２’）との磁界の間を遮蔽するシールド部材５５を備えたことを特徴とする。
【００１４】
本発明による請求項３記載の金属検出機のバランス調整方法は、
被検査体Ｗが搬送される検査空間Ｓ内に直交する二軸の磁界を生成する各検出ヘッド３０，４０を共に有した金属検出機のバランス調整方法であって、
前記一方の検出ヘッド３０と前記他方の検出ヘッド４０のそれぞれの生成磁界が交わる共有領域Ｌ１（Ｌ１’）にて前記一方の検出ヘッド３０あるいは前記他方の検出ヘッド４０の何れか一方の各受信コイル３２，３３（４２，４３）の誘起電圧の平衡を得た後、前記一方の検出ヘッド３０あるいは前記他方の検出ヘッド４０の何れか一方の生成磁界が前記共有領域Ｌ１（Ｌ１’）外まで延びていて前記共有領域Ｌ１，Ｌ１’と隣接している独立領域Ｌ２（Ｌ２’）にて前記一方の検出ヘッド３０あるいは前記他方の検出ヘッド４０の何れか一方の各受信コイル４２，４３（３２，３３）の誘起電圧の平衡を得ることを特徴とする。
【００１５】
【発明の実施の形態】
以下、本発明の実施の形態を図面を参照して具体的に説明する。
図１は本発明の金属検出機の検出ヘッドを示す概略図である。
なお、以下に説明する実施の形態において、上述した従来の技術と同一または同等部分には同一符号を付して説明する。
【００１６】
図１に示すように、金属検出機は、被検査体Ｗが搬送される検査空間Ｓ内に直交する二軸の磁界を生成する二組の各検出ヘッド３０，４０を共に有している。本実施の形態では、一方の検出ヘッド３０が同軸型検出ヘッド３０として構成され、他方の検出ヘッド４０が対向型検出ヘッド４０として構成されている。
【００１７】
同軸型検出ヘッド３０は、中央に送信コイル３１の前後の同軸上に、それぞれ逆巻きの各受信コイル３２，３３を配置して、被検査体Ｗの通過方向（図１中Ａ方向）に対して平行な磁力線を生成するヘッドコイル配置をなす。同軸型検出ヘッド３０は、各コイル３１，３２，３３の内側に連続する検査空間Ｓをなしている。同軸型検出ヘッド３０は、検査空間Ｓ内において送信コイル３１の交番磁界により図１中左右方向（図６参照）の磁束を発生させることにより、この磁束に交わる各送信コイル３２，３３にそれぞれ位相が逆の誘起電圧Ｖ１，Ｖ２を発生させる。各受信コイル３２，３３は、送信コイル３１に対して等しい距離に配置され、非検出状態では誘起電圧Ｖ１，Ｖ２の大きさが等しく差が０となる。
【００１８】
対向型検出ヘッド４０は、同軸型検出ヘッド３０の一側（上側）に送信コイル４１を配置し、この送信コイル４１に対向するように同軸型検出ヘッド３０の他側（下側）に各受信コイル４２，４３を併設して配置して、被検査体Ｗの通過方向（図３中Ａ方向）に対して直交する磁力線を生成するヘッドコイル配置をなす。対向型検出ヘッド４０は、送信コイル４１と各受信コイル４２，４３との間に前記検査空間Ｓをなしている。対向型検出ヘッド４０は、検査空間Ｓ内において送信コイル４１の交番磁界により図１中上下方向（図６参照）の磁束を発生させるとにより、この磁束に交わる各送信コイル４２，４３にそれぞれ位相が逆の誘起電圧Ｖ３，Ｖ４を発生させる。各受信コイル４２，４３は、送信コイル４１に対して等しい距離に配置され、非検出状態では誘起電圧Ｖ３，Ｖ４の大きさが等しく差が０となる。この対向型検出ヘッド４０は、検査空間Ｓにおいて、同軸型検出ヘッド３０の磁束と直交する磁束を生じる。
【００１９】
上記各検出ヘッド３０，４０は、検査空間Ｓ内に搬送コンベア（不図示）などの搬送手段が貫通するように配置され、図１に示す略ロ字型の筐体３５内部に収容される。筐体３５は、金属（例えばアルミ合金やステンレス鋼）などの磁気シールドの材質で形成されている。そして、搬送コンベアによって被検査体Ｗを搬送して検査空間Ｓ内を通過させる。
【００２０】
上記構成の金属検出機では、同軸型検出ヘッド３０において、金属Ｍが混入した被検査体Ｗが搬送手段によって図１中Ａ方向に進行して手前の受信コイル３２内に移動すると、受信コイル３２内の磁束密度が増し、逆に受信コイル３３内の磁束密度が減少する。このため、受信コイル３２の誘起電圧Ｖ１は、受信コイル３３の誘起電圧Ｖ２よりも大きくなる。次いで、進行した被検査体Ｗが受信コイル３３内まで移動すると、受信コイル３２内よりも受信コイル３３内の磁束密度の方が大きくなるため、誘起電圧Ｖ１より誘起電圧Ｖ２の方が大きくなる。このようにして、同軸型検出ヘッド３０から出力される誘起電圧Ｖ１，Ｖ２の差の変化（磁界の揺らぎ）に基づいて、検査空間Ｓ内を通過した被検査体Ｗに金属Ｍが混入しているか否かを判定することができる。
【００２１】
また、対向型検出ヘッド４０において、金属Ｍが混入した被検査体Ｗが搬送手段によって図１中Ａ方向に進行して送信コイル４１と手前の受信コイル４２との間に移動すると、送信コイル４１・受信コイル４２間の磁束密度が増し、逆に送信コイル４１・受信コイル４３間の磁束密度が減少する。このため、受信コイル４２の誘起電圧Ｖ３は、受信コイル４３の誘起電圧Ｖ４よりも大きくなる。次いで、進行した被検査体Ｗが送信コイル４１と受信コイル４３との間に移動すると、送信コイル４１・受信コイル４２間よりも、送信コイル４１・受信コイル４３間の磁束密度の方が大きくなるため、誘起電圧Ｖ３より誘起電圧Ｖ４の方が大きくなる。このようにして、同軸型検出ヘッド４０から出力される誘起電圧Ｖ３，Ｖ４の差の変化（磁界の揺らぎ）に基づいて、検査空間Ｓ内を通過した被検査体Ｗに金属Ｍが混入しているか否かを判定することができる。
【００２２】
すなわち、本実施の形態の金属検出機では、被検査体Ｗに混入した金属Ｍが針形状や薄板形状で、且つ、磁性体の場合、同軸型検出ヘッド３０で生じる磁束に対して略直交する配置である時、対向型検出ヘッド４０で生じる磁束に対して平行な配置となる。これにより、同軸型検出ヘッド３０では磁束の変化が少なく誘起電圧Ｖ１，Ｖ２の差が小さいので金属Ｍの検出感度が落ちるが、対向型検出ヘッド４０では磁束の変化が多く誘起電圧Ｖ３，Ｖ４の差が大きいので金属Ｍの検出感度が良好となる。逆に、同じく針形状や薄板形状で、且つ、磁性体の金属Ｍが同軸型検出ヘッド３０で生じる磁束に対して平行な配置である時、対向型検出ヘッド４０で生じる磁束に対して略直交する配置となる。これにより、対向型検出ヘッド４０では磁束の変化が少なく誘起電圧Ｖ３，Ｖ４の差が小さいので金属Ｍの検出感度が落ちるが、同軸型検出ヘッド３０では磁束の変化が多く誘起電圧Ｖ１，Ｖ２の差が大きいので金属Ｍの検出感度が良好となる。
【００２３】
さらに、本実施の形態の金属検出機では、被検査体Ｗに混入した金属Ｍが針形状や薄板形状で、且つ、非磁性体の場合、同軸型検出ヘッド３０で生じる磁束に対して平行な配置である時、対向型検出ヘッド４０で生じる磁束に対して略直交する配置となる。これにより、同軸型検出ヘッド３０では磁束の変化が少なく誘起電圧Ｖ１，Ｖ２の差が小さいので金属Ｍの検出感度が落ちるが、対向型検出ヘッド４０では磁束の変化が多く誘起電圧Ｖ３，Ｖ４の差が大きいので金属Ｍの検出感度が良好となる。逆に、同じく針形状や薄板形状で、且つ、非磁性体の金属Ｍが同軸型検出ヘッド３０で生じる磁束に対して略直交する配置である時、対向型検出ヘッド４０で生じる磁束に対して平行な配置となる。これにより、対向型検出ヘッド４０では磁束の変化が少なく誘起電圧Ｖ３，Ｖ４の差が小さいので金属Ｍの検出感度が落ちるが、同軸型検出ヘッド３０では磁束の変化が多く誘起電圧Ｖ１，Ｖ２の差が大きいので金属Ｍの検出感度が良好となる。
【００２４】
このように、上述した金属検出機は、互いに磁束が直交する同軸型検出ヘッド３０および対向型検出ヘッド４０を共に用いることで、一方の検出ヘッドで検出し難い配置にある金属Ｍ（磁性体あるいは非磁性体）であっても、他方の検出ヘッドで検出し、被検査体Ｗに混入した金属Ｍをもれなく検出する。
【００２５】
上記構成の金属検出機において、製造・組立時の誤差などによって非検出状態にて、同軸型検出ヘッド３０では受信コイル３２，３３における各誘起電圧Ｖ１，Ｖ２の差が０とならず、対向型検出ヘッド４０では受信コイル４２，４３における各誘起電圧Ｖ３，Ｖ４の差が０とならず、それぞれ誘起電圧の平衡が狂うことがある。これにより、金属Ｍの検出が正確に行えなくなるでバランス調整が必要となる。
【００２６】
本実施の形態の金属検出機では、下記のバランス調整機構を備えている。
図２はバランス調整機構を示す斜視図である。
【００２７】
図２に示すように、上述の金属検出機において、同軸型検出ヘッド３０の生成磁界（図２中二点鎖線で示す）が、対向型検出ヘッド４０の生成磁界（図２中一点鎖線で示す）内に交わるように配されている。これにより、同軸型検出ヘッド３０の生成磁界が、同軸型検出ヘッド３０と対向型検出ヘッド４０のそれぞれの生成磁界が交わる共有領域Ｌ１をなす。
【００２８】
また、対向型検出ヘッド４０は、各コイル４１，４２，４３が図２中右側に延長されている。これにより、対向型検出ヘッド４０の生成磁界（図２中一点鎖線で示す）において同軸型検出ヘッド３０の生成磁界の影響しない領域まで延びた部分が共有領域Ｌ１と隣接している独立領域Ｌ２をなす。
【００２９】
上記構成において、筐体３５には、調整部５１，５２が設けられている。調整部は、磁性金属体（例えば鉄）あるいは非磁性金属体（例えばアルミ合金やステンレス鋼など）からなる金属棒であり、好ましくは図２に示すネジとして構成されている。調整部には、同軸側調整部（第一調整部）５１と対向側調整部（第二調整部）５２とがある。
【００３０】
同軸側調整部５１は、同軸型検出ヘッド３０の生成磁界である共有領域Ｌ１内に至るように対向型検出ヘッド４０の生成磁界を通過して筐体３５に形成された凹部３５ａ内にて、共有領域Ｌ１内を移動可能にして取り付けられている。同軸側調整部５１がネジとして構成されている場合では、その回転によって共有領域Ｌ１内を進退移動する。
【００３１】
対向側調整部５２は、対向型検出ヘッド４０の生成磁界であって同軸型検出ヘッド３０の生成磁界から延長された独立領域Ｌ２内のみに至るように筐体３５に形成された凹部３５ｂ内にて、独立領域Ｌ２内を移動可能にして取り付けられている。対向側調整部５２がネジとして構成されている場合では、その回転によって独立領域Ｌ２内を進退移動する。
【００３２】
バランス調整に際しては、最初に共有領域Ｌ１をなす同軸型検出ヘッド３０にかかり、同軸側調整部５１を移動させる。同軸側調整部５１は、その移動により同軸型検出ヘッド３０が生じる磁束に変化を与えて各受信コイル３２，３３の間の誘起電圧の平衡を得る。次いで、独立領域Ｌ２をなす対向型検出ヘッド４０にかかり、対向側調整部５２を移動させる。対向側調整部５２は、その移動により対向型検出ヘッド４０が生じる磁束に変化を与えて各受信コイル４２，４３の間の誘起電圧の平衡を得る。
【００３３】
上記バランス調整にかかり、共有領域Ｌ１（同軸型検出ヘッド３０）における誘起電圧の平衡を得る際、同軸側調整部５１が対向型検出ヘッド４０の生成磁界を通過しているために、対向型検出ヘッド４０の磁束に影響を与える。ところが、次に独立領域Ｌ２（対向型検出ヘッド４０）における誘起電圧の平衡を得る際には、独立領域Ｌ２が共有領域Ｌ１と独立しているため同軸型検出ヘッド３０の磁束に影響を与えることがない。これにより、同軸型検出ヘッド３０および対向型検出ヘッド４０それぞれの誘起電圧の平衡を得ることが可能である。このように、上述したバランス調整機構によれば、各検出ヘッド３０，４０の誘起電圧の平衡の調整を容易に行うことが可能となる。
【００３４】
ところで、共有領域Ｌ１（同軸型検出ヘッド３０側）の磁束に変化を与えて誘起電圧の平衡を得る同軸側調整部５１と、独立領域Ｌ２（対向型検出ヘッド４０側）の磁束に変化を与えて誘起電圧の平衡を得る対向側調整部５２とは、共に独立領域Ｌ２側に設けられている。また、独立領域Ｌ２は、被検査体Ｗを通過させる検査空間Ｓに関与しない部位に延長されている。この構成にかかり、共有領域Ｌ１と独立領域Ｌ２との磁界の間には、各調整部５１，５２にかかる部位の共有領域Ｌ１と独立領域Ｌ２との磁界の間を遮蔽するシールド部材５５が設けられている。シールド部材５５は、筐体３５と同様に、金属（例えばアルミ合金やステンレス鋼）などの磁気シールドの材質で板状に形成されている。そして筐体３５内にて各領域Ｌ１，Ｌ２を分割する如く設けられている。
【００３５】
このように、シールド部材５５を設ければ、独立領域Ｌ２が共有領域Ｌ１と磁気的に分けられるので、各領域Ｌ１，Ｌ２のバランス調整する際に、互いの影響が少なくなって、より容易に調整を行うことが可能となる。また、シールド部材５５により、独立領域Ｌ２が狭い範囲であっても上記の効果を得ることが可能であり、上記構成とした金属検出機の小型化を図ることができる。
【００３６】
以下、別のバランス調整機構について説明する。
図３は別のバランス調整機構を示す斜視図である。
【００３７】
図３に示すように、上述の金属検出機において、対向型検出ヘッド４０の生成磁界（図３中一点鎖線で示す）が、同軸型検出ヘッド３０の生成磁界（図３中二点鎖線で示す）内に交わるように配されている。これにより、対向型検出ヘッド４０の生成磁界において、同軸型検出ヘッド３０の生成磁界と交わる部分が、同軸型検出ヘッド３０と対向型検出ヘッド４０のそれぞれの生成磁界が交わる共有領域Ｌ１’をなす。
【００３８】
また、同軸型検出ヘッド３０は、各コイル３１，３２，３３が図３中右側に延長されている。これにより、同軸型検出ヘッド３０の生成磁界（図３中二点鎖線で示す）において対向型検出ヘッド４０の生成磁界の影響しない領域まで延びた部分が共有領域Ｌ１’と隣接している独立領域Ｌ２’をなす。
【００３９】
上記構成において、筐体３５には、調整部５１’，５２’が設けられている。調整部は、磁性金属体（例えば鉄）あるいは非磁性金属体（例えばアルミ合金やステンレス鋼など）からなる金属棒であり、好ましくは図３に示すネジとして構成されている。調整部には、同軸側調整部（第一調整部）５１’と対向側調整部（第二調整部）５２’とがある。
【００４０】
対向側調整部５２’は、対向型検出ヘッド４０の生成磁界である共有領域Ｌ１’内に至るように延長された同軸型検出ヘッド３０の生成磁界を通過して筐体３５に形成された凹部３５ａ内にて、共有領域Ｌ１’内を移動可能にして取り付けられている。対向側調整部５２’がネジとして構成されている場合では、その回転によって共有領域Ｌ１’内を進退移動する。
【００４１】
同軸側調整部５１’は、同軸型検出ヘッド３０の生成磁界である独立領域Ｌ２’内のみに至るように筐体３５に形成された凹部３５ｂ内にて、独立領域Ｌ２’内を移動可能にして取り付けられている。同軸側調整部５１’がネジとして構成されている場合では、その回転によって独立領域Ｌ２’内を進退移動する。
【００４２】
バランス調整に際しては、最初に共有領域Ｌ１’をなす対向型検出ヘッド４０にかかり、対向側調整部５２’を移動させる。対向側調整部５２’は、その移動により対向型検出ヘッド４０が生じる磁束に変化を与えて各受信コイル４２，４３の間の誘起電圧の平衡を得る。次いで、独立領域Ｌ２’をなす同軸型検出ヘッド３０にかかり、同軸側調整部５１’を移動させる。同軸側調整部５１’は、その移動により同軸型検出ヘッド３０が生じる磁束に変化を与えて各受信コイル３２，３３の間の誘起電圧の平衡を得る。
【００４３】
上記バランス調整にかかり、共有領域Ｌ１’（対向型検出ヘッド４０）における誘起電圧の平衡を得る際、対向側調整部５２’が同軸型検出ヘッド３０の生成磁界を通過しているために、同軸型検出ヘッド３０の磁束に影響を与える。ところが、次に独立領域Ｌ２’（同軸型検出ヘッド３０）における誘起電圧の平衡を得る際には、独立領域Ｌ２’が共有領域Ｌ１’と独立しているため対向型検出ヘッド４０の磁束に影響を与えることがない。これにより、同軸型検出ヘッド３０および対向型検出ヘッド４０それぞれの誘起電圧の平衡を得ることが可能である。このように、上述したバランス調整機構によれば、各検出ヘッド３０，４０の誘起電圧の平衡の調整を容易に行うことが可能となる。
【００４４】
ところで、共有領域Ｌ１’（対向型検出ヘッド４０側）の磁束に変化を与えて誘起電圧の平衡を得る対向側調整部５２’と、独立領域Ｌ２（同軸型検出ヘッド３０側）の磁束に変化を与えて誘起電圧の平衡を得る同軸側調整部５１’とは、共に独立領域Ｌ２’側に設けられている。また、独立領域Ｌ２’は、被検査体Ｗを通過させる検査空間Ｓに関与しない部位に延長されている。この構成にかかり、共有領域Ｌ１’と独立領域Ｌ２’との磁界の間には、各調整部５１’，５２’にかかる部位の共有領域Ｌ１’と独立領域Ｌ２’との磁界の間を遮蔽するシールド部材５５が設けられている。シールド部材５５は、筐体３５と同様に、金属（例えばアルミ合金やステンレス鋼）などの磁気シールドの材質で板状に形成されている。そして筐体３５内にて各領域Ｌ１’，Ｌ２’を分割する如く設けられている。
【００４５】
このように、シールド部材５５を設ければ、独立領域Ｌ２’が共有領域Ｌ１’と磁気的に分けられるので、各領域Ｌ１’，Ｌ２’のバランス調整する際に、互いの影響が少なくなって、より容易に調整を行うことが可能となる。また、シールド部材５５により、独立領域Ｌ２’が狭い範囲であっても上記の効果を得ることが可能であり、上記構成とした金属検出機の小型化を図ることができる。
【００４６】
【発明の効果】
以上説明したように本発明による金属検出機は、一方の検出ヘッドの生成磁界と他方の検出ヘッドの生成磁界が交わる共有領域と、上記何れかの生成磁界が共有領域外まで延ばされて共有領域と隣接している独立領域とを得て、それぞれの領域を各調整部にて個々にバランス調整する。これにより、最初に共有領域における検出ヘッドのバランス調整を行う際には独立領域における検出ヘッドの磁束に影響を与えるが、その後独立領域における検出ヘッドのバランス調整では共有領域の検出ヘッドの磁束に影響を与えずバランス調整が行えるので、二軸二組の各検出ヘッドの誘起電圧の平衡の調整を容易に行うことができる。
【００４７】
また、共有領域と独立領域との磁界の間を遮蔽するシールド部材を設けることにより、独立領域が共有領域と磁気的に分けられるので、各領域のバランス調整する際に、互いの影響が少なくなって、より容易に調整を行うことが可能となる。さらに、シールド部材により、独立領域が狭い範囲であっても上記の効果が得られるので、上記構成とした金属検出機の小型化を図ることができる。
【図面の簡単な説明】
【図１】本発明の金属検出機の検出ヘッドを示す概略図。
【図２】バランス調整機構を示す斜視図。
【図３】別のバランス調整機構を示す斜視図。
【図４】従来の金属検出機の検出ヘッドを示す概略図。
【図５】従来のバランス調整機構を示す斜視図。
【図６】二軸二組の検出ヘッドを示す概略図。
【符号の説明】
３０…同軸型検出ヘッド（一方の検出ヘッド）、３２…受信コイル、３３…受信コイル、４０…対向型検出ヘッド（他方の検出ヘッド）、４２…受信コイル、４３…受信コイル、５１…同軸側調整部（第一調整部）、５１’…同軸側調整部（第一調整部）、５２…対向側調整部（第二調整部）、５２’…対向側調整部（第二調整部）、５５…シールド部材、Ｌ１…共有領域、Ｌ１’…共有領域、Ｌ２…独立領域、Ｌ２’…独立領域。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal detector that detects a metal object mixed in an object to be inspected, and more particularly to a metal detector that includes an adjustment mechanism that adjusts the balance of magnetic flux.
[0002]
[Prior art]
The metal detector determines whether or not metal is mixed in the inspection object by detecting a change that the metal mixed in the inspection object gives to the inspection magnetic field.
FIG. 4 is a diagram showing the detection principle of the detection head in the metal detector. As shown in FIG. 4, conventionally, for example, receiving coils 32 and 33 are arranged before and after the central transmitting coil 31, and magnetic lines of force parallel to the passing direction of the object to be inspected W (A direction in FIG. 4). A coaxial detection head 30 having a generated head coil arrangement is used.
[0003]
In the detection head 30, in the inspection space S continuous inside the coils 31, 32, and 33, the induced voltages V <b> 1 that are opposite in phase to the receiving coils 32 and 33 that intersect the magnetic flux generated by the alternating magnetic field of the central transmission coil 31. , V2 is generated. The receiving coils 32 and 33 are arranged at the same distance from the transmitting coil 31, and the induced voltages V1 and V2 are equal in magnitude in the non-detection state where the object W is far from the examination space S and the difference is zero. It becomes.
[0004]
For example, when the inspected object W mixed with the metal M travels in the direction A in FIG. 4 and moves into the front receiving coil 32, the magnetic flux density in the receiving coil 32 increases, and conversely, the magnetic flux in the receiving coil 33. Density decreases. For this reason, the induced voltage V1 of the receiving coil 32 becomes larger than the induced voltage V2 of the receiving coil 33. Next, when the inspected object W advances to the inside of the receiving coil 33, the magnetic flux density in the receiving coil 33 becomes larger than that in the receiving coil 32. Therefore, the induced voltage V2 becomes larger than the induced voltage V1. In this way, whether or not the metal M is mixed in the inspection object W that has passed through the inspection space S based on the change in the difference between the induced voltages V1 and V2 output from the detection head 30 (magnetic field fluctuation). Can be determined.
[0005]
In general, the detection head 30 is arranged so that a conveyor (not shown) passes through the inspection space S, and is housed in a substantially rectangular housing 35 shown in FIG. The housing 35 is formed of a magnetic shield material such as metal (for example, aluminum alloy or stainless steel). And the to-be-inspected object W is conveyed with a conveyance conveyor, and the inside of the inspection space S is allowed to pass through.
[0006]
In the above configuration, the difference between the induced voltages V1 and V2 in the receiving coils 32 and 33 in the non-detected state may not be zero in the non-detected state due to manufacturing and assembly errors, and the balance of the induced voltages may be out of order. For this reason, the metal M cannot be detected accurately. Therefore, balance adjustment is necessary. In the conventional balance adjustment, as shown in FIG. 5, a metal plate 36 that is a magnetic body and a non-magnetic body is attached to a portion of the inspection space S of the housing 35, or a magnetic body and a non-magnetic body are provided on the outer side. The balance was adjusted by inserting a metal rod 37 (for example, a screw). Adjustment with the metal plate 36 is performed at a position where the induced voltage is balanced by changing the attachment position with respect to the housing 35. The adjustment with the metal rod 37 is fixed at a position where the induced voltage is balanced by changing the insertion depth with respect to the housing 35.
[0007]
[Problems to be solved by the invention]
By the way, in the coaxial detection head 30 used in the above-described conventional metal detector, for example, with respect to the needle-shaped or thin-plate-shaped metal M, the magnetic body that is the metal M having the above-described shape is disposed substantially orthogonal to the magnetic flux. Alternatively, in the case where a non-magnetic material, which is the metal M having the above shape, is mixed in the test object W in an arrangement parallel to the magnetic flux, since the change in the magnetic flux is small, the difference between the induced voltages V1 and V2 is small and the detection sensitivity is lowered. End up. That is, there is a possibility that the metal M mixed in the inspection subject W cannot be detected.
[0008]
Therefore, as shown in FIG. 6, a two-axis two-set metal detector using a detection head 40 having a magnetic flux direction orthogonal to the detection head 30 together with the detection head 30 can be considered. As shown in FIG. 6, for example, the detection head 40 includes a transmission coil 41 disposed above the detection head 30, and disposed adjacent reception coils 42 and 43 below the detection head 30 facing the transmission coil 41. The head type is a counter type in which a head coil is arranged to generate a magnetic force line perpendicular to the passing direction of the object to be inspected W (A direction in FIG. 4). The detection head 40 generates induced voltages V3 and V4 having opposite phases in the transmission coils 42 and 43 that intersect the magnetic flux generated by the alternating magnetic field of the transmission coil 41 in the inspection space S, respectively. The receiving coils 42 and 43 are arranged at an equal distance from the transmitting coil 41, and the induced voltages V3 and V4 have the same magnitude and a difference of 0 in the non-detected state.
[0009]
In this metal detector, as shown in FIG. 6, the detection head 30 generates a magnetic flux in the left-right direction, and the detection head 40 generates a magnetic flux in the vertical direction. Even if the magnetic body, which is a needle-shaped or thin-plate-shaped metal M, is arranged substantially perpendicular to the magnetic flux with respect to the magnetic flux of the detection head 30, the detection head 40 is arranged parallel to the magnetic flux. Therefore, the change in magnetic flux increases, the difference between the induced voltages V3 and V4 is large, and the detection sensitivity is good. Further, even if the non-magnetic material that is a needle-shaped or thin-plate-shaped metal M with respect to the magnetic flux of the detection head 30 is arranged parallel to the magnetic flux, the detection head 40 is arranged so as to be orthogonal to the magnetic flux. Therefore, the change in magnetic flux increases, the difference between the induced voltages V3 and V4 is large, and the detection sensitivity is good. In this manner, the detection head 40 detects the metal M that is difficult to detect with the detection head 30, and conversely, the detection head 30 detects the metal M that is difficult to detect with the detection head 40.
[0010]
However, even if the above-described two-axis two-piece metal detector attempts to obtain the balance of the induced voltage of the detection head 30 by the balance adjustment, the balance of the induced voltage in the detection head 40 cannot be obtained due to the influence. . On the contrary, when it is attempted to obtain the balance of the induced voltage of the detection head 40 by the balance adjustment, the balance of the induced voltage at the detection head 30 cannot be obtained due to the influence. As described above, in the two-axis two-set metal detector, there is a problem that it is difficult to obtain the balance of the induced voltages of both the detection heads 30 and 40.
[0011]
Therefore, in order to solve the above-described problems, the present invention provides a metal detector that can easily adjust the balance of the induced voltage of each detection head in the metal detector that forms each of the two-axis and two-set detection heads, and It aims at providing the balance adjustment method of a metal detector.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a metal detector according to claim 1 of the present invention comprises:
A metal detector having both detection heads 30 and 40 that generate two perpendicular magnetic fields in the inspection space S in which the object to be inspected W is conveyed,
A shared region L1 (L1 ′) where the generated magnetic fields of the one detection head 30 and the other detection head 40 intersect;
The generated magnetic field of either the one detection head 30 or the other detection head 40 extends to the outside L1 (L1 ′) of the shared area and is adjacent to the shared area L1 (L1 ′). L2 ′)
An adjustment unit arranged in the shared region L1 (L1 ′) to obtain a balance of induced voltages of the receiving coils 32 and 33 (42 and 43) of either the one detection head 30 or the other detection head 40. 51 (52 '),
An adjustment unit arranged in the independent region L2 (L2 ′) to obtain a balance of induced voltages of the other receiving coils 42, 43 (32, 33) of either the one detection head 30 or the other detection head 40 52 (51 '),
It is provided with.
[0013]
The metal detector according to claim 2 is the metal detector according to claim 1,
The adjustment parts 51, 52 (51 ′, 52 ′) are arranged in parts not involved in the examination space S, and the shared region L1 of the part related to the adjustment parts 51, 52 (51 ′, 52 ′) A shield member 55 that shields between the magnetic field between (L1 ′) and the independent region L2 (L2 ′) is provided.
[0014]
According to the third aspect of the present invention, there is provided a metal detector balance adjustment method according to the present invention.
A method for adjusting the balance of a metal detector having both detection heads 30 and 40 that generate two perpendicular magnetic fields in an inspection space S in which an object to be inspected W is conveyed,
Each receiving coil of either the one detection head 30 or the other detection head 40 in the common region L1 (L1 ′) where the generated magnetic fields of the one detection head 30 and the other detection head 40 intersect each other. After obtaining the balance of the induced voltages 32 and 33 (42 and 43), the generated magnetic field of either the one detection head 30 or the other detection head 40 extends to the outside of the shared region L1 (L1 ′). In the independent region L2 (L2 ′) adjacent to the shared regions L1 and L1 ′, the receiving coils 42 and 43 (32, 32, 32) of either the one detection head 30 or the other detection head 40 are used. 33) to obtain the equilibrium of the induced voltage.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic view showing a detection head of a metal detector of the present invention.
In the embodiments described below, the same or equivalent parts as those in the conventional technique described above are denoted by the same reference numerals.
[0016]
As shown in FIG. 1, the metal detector has two sets of detection heads 30 and 40 that generate biaxial magnetic fields orthogonal to each other in the inspection space S in which the inspection object W is conveyed. In the present embodiment, one detection head 30 is configured as a coaxial detection head 30, and the other detection head 40 is configured as a counter-type detection head 40.
[0017]
The coaxial type detection head 30 is arranged in the center on the same axis before and after the transmission coil 31 with each of the reception coils 32 and 33 wound in reverse, respectively, with respect to the passing direction of the object to be inspected W (direction A in FIG. 1). A head coil arrangement that generates parallel lines of magnetic force is formed. The coaxial detection head 30 forms an inspection space S that is continuous inside the coils 31, 32, and 33. The coaxial detection head 30 generates a magnetic flux in the left-right direction in FIG. 1 (see FIG. 6) by the alternating magnetic field of the transmission coil 31 in the inspection space S, so that the phase is applied to each of the transmission coils 32 and 33 that intersect this magnetic flux. Generates opposite induced voltages V1 and V2. The receiving coils 32 and 33 are arranged at an equal distance from the transmitting coil 31, and the induced voltages V1 and V2 have the same magnitude and the difference is zero in the non-detected state.
[0018]
In the opposed detection head 40, a transmission coil 41 is disposed on one side (upper side) of the coaxial detection head 30, and each reception is performed on the other side (lower side) of the coaxial detection head 30 so as to face the transmission coil 41. The coils 42 and 43 are disposed side by side to form a head coil that generates magnetic field lines that are orthogonal to the direction of passage of the object W to be inspected (direction A in FIG. 3). The counter-type detection head 40 forms the inspection space S between the transmission coil 41 and the reception coils 42 and 43. When the opposing detection head 40 generates a magnetic flux in the vertical direction in FIG. 1 (see FIG. 6) in the inspection space S by the alternating magnetic field of the transmission coil 41, the opposing detection head 40 has a phase on each of the transmission coils 42 and 43 that intersect this magnetic flux. Generates opposite induced voltages V3 and V4. The receiving coils 42 and 43 are arranged at an equal distance from the transmitting coil 41, and the induced voltages V3 and V4 have the same magnitude and a difference of 0 in the non-detected state. The opposing detection head 40 generates a magnetic flux orthogonal to the magnetic flux of the coaxial detection head 30 in the inspection space S.
[0019]
Each of the detection heads 30 and 40 is disposed so that a conveying means such as a conveyor (not shown) passes through the inspection space S, and is accommodated in a substantially square-shaped casing 35 shown in FIG. The housing 35 is formed of a magnetic shield material such as metal (for example, aluminum alloy or stainless steel). And the to-be-inspected object W is conveyed with a conveyance conveyor, and the inside of the inspection space S is allowed to pass through.
[0020]
In the metal detector having the above configuration, in the coaxial detection head 30, when the inspection object W mixed with the metal M travels in the direction A in FIG. The magnetic flux density inside increases, and conversely, the magnetic flux density inside the receiving coil 33 decreases. For this reason, the induced voltage V1 of the receiving coil 32 becomes larger than the induced voltage V2 of the receiving coil 33. Next, when the inspected object W advances to the inside of the receiving coil 33, the magnetic flux density in the receiving coil 33 becomes larger than that in the receiving coil 32. Therefore, the induced voltage V2 becomes larger than the induced voltage V1. In this way, the metal M is mixed into the inspection object W that has passed through the inspection space S based on the change in the difference between the induced voltages V1 and V2 output from the coaxial detection head 30 (magnetic field fluctuation). It can be determined whether or not.
[0021]
Further, in the counter-type detection head 40, when the object W into which the metal M is mixed advances in the direction A in FIG. 1 by the conveying means and moves between the transmission coil 41 and the front reception coil 42, the transmission coil 41. -The magnetic flux density between the receiving coils 42 increases, and conversely, the magnetic flux density between the transmitting coils 41 and the receiving coils 43 decreases. For this reason, the induced voltage V3 of the receiving coil 42 is larger than the induced voltage V4 of the receiving coil 43. Next, when the advanced object W moves between the transmission coil 41 and the reception coil 43, the magnetic flux density between the transmission coil 41 and the reception coil 43 becomes larger than between the transmission coil 41 and the reception coil. Therefore, the induced voltage V4 is larger than the induced voltage V3. In this way, based on the change in the difference between the induced voltages V3 and V4 output from the coaxial detection head 40 (magnetic field fluctuation), the metal M is mixed into the inspection object W that has passed through the inspection space S. It can be determined whether or not.
[0022]
That is, in the metal detector according to the present embodiment, when the metal M mixed in the object to be inspected W has a needle shape or a thin plate shape and is a magnetic body, it is substantially orthogonal to the magnetic flux generated in the coaxial detection head 30. When arranged, the arrangement is parallel to the magnetic flux generated by the opposed detection head 40. As a result, in the coaxial detection head 30, the change in magnetic flux is small and the difference between the induced voltages V1 and V2 is small, so the detection sensitivity of the metal M is lowered. However, in the opposed detection head 40, the change in magnetic flux is large and the induced voltages V3 and V4 are reduced. Since the difference is large, the detection sensitivity of the metal M is good. On the other hand, when the magnetic metal M is arranged parallel to the magnetic flux generated by the coaxial detection head 30, it is substantially orthogonal to the magnetic flux generated by the opposed detection head 40. It becomes arrangement to do. As a result, in the opposed detection head 40, the change in the magnetic flux is small and the difference between the induced voltages V3 and V4 is small, so the detection sensitivity of the metal M is lowered. However, in the coaxial detection head 30, the change in the magnetic flux is large and the induced voltages V1, V2 are reduced. Since the difference is large, the detection sensitivity of the metal M is good.
[0023]
Furthermore, in the metal detector according to the present embodiment, when the metal M mixed in the object to be inspected W has a needle shape or a thin plate shape and is a non-magnetic material, it is parallel to the magnetic flux generated in the coaxial detection head 30. When arranged, the arrangement is substantially orthogonal to the magnetic flux generated by the opposed detection head 40. As a result, in the coaxial detection head 30, the change in magnetic flux is small and the difference between the induced voltages V1 and V2 is small, so the detection sensitivity of the metal M is lowered. However, in the opposed detection head 40, the change in magnetic flux is large and the induced voltages V3 and V4 are reduced. Since the difference is large, the detection sensitivity of the metal M is good. On the other hand, when the non-magnetic metal M is arranged in the shape of a needle or a thin plate and substantially perpendicular to the magnetic flux generated in the coaxial detection head 30, the magnetic flux generated in the opposed detection head 40 is reduced. Parallel arrangement. As a result, in the opposed detection head 40, the change in the magnetic flux is small and the difference between the induced voltages V3 and V4 is small, so the detection sensitivity of the metal M is lowered. However, in the coaxial detection head 30, the change in the magnetic flux is large and the induced voltages V1, V2 are reduced. Since the difference is large, the detection sensitivity of the metal M is good.
[0024]
In this way, the above-described metal detector uses the coaxial detection head 30 and the opposed detection head 40 in which the magnetic fluxes are orthogonal to each other, so that the metal M (magnetic material or The non-magnetic material is detected by the other detection head, and the metal M mixed in the object to be inspected W is detected without exception.
[0025]
In the metal detector having the above-described configuration, the difference between the induced voltages V1 and V2 in the receiving coils 32 and 33 does not become zero in the coaxial detection head 30 in a non-detected state due to errors in manufacturing and assembly, etc. In the detection head 40, the difference between the induced voltages V3 and V4 in the receiving coils 42 and 43 does not become zero, and the balance of the induced voltages may be out of order. As a result, the metal M cannot be detected accurately and balance adjustment is required.
[0026]
The metal detector of the present embodiment includes the following balance adjustment mechanism.
FIG. 2 is a perspective view showing the balance adjusting mechanism.
[0027]
As shown in FIG. 2, in the metal detector described above, the magnetic field generated by the coaxial detection head 30 (indicated by a two-dot chain line in FIG. 2) is generated by the counter-type detection head 40 (indicated by a one-dot chain line in FIG. 2). ) Thereby, the generated magnetic field of the coaxial detection head 30 forms a shared region L1 where the generated magnetic fields of the coaxial detection head 30 and the opposing detection head 40 intersect.
[0028]
In the opposed detection head 40, the coils 41, 42, 43 are extended to the right in FIG. As a result, in the generated magnetic field of the opposing detection head 40 (indicated by the alternate long and short dash line in FIG. 2), the independent region L2 in which the portion extending to the region not affected by the generated magnetic field of the coaxial detection head 30 is adjacent to the shared region L1. Eggplant.
[0029]
In the above configuration, the casing 35 is provided with adjusting units 51 and 52. The adjusting portion is a metal rod made of a magnetic metal body (for example, iron) or a nonmagnetic metal body (for example, aluminum alloy or stainless steel), and is preferably configured as a screw shown in FIG. The adjustment unit includes a coaxial adjustment unit (first adjustment unit) 51 and a counter adjustment unit (second adjustment unit) 52.
[0030]
The coaxial adjustment unit 51 passes through the generated magnetic field of the opposing detection head 40 so as to reach the shared region L1 that is the generated magnetic field of the coaxial detection head 30, and in the recess 35a formed in the housing 35. It is attached so as to be movable in the shared area L1. When the coaxial adjustment part 51 is configured as a screw, it moves forward and backward in the shared region L1 by its rotation.
[0031]
The facing side adjustment unit 52 is in a recess 35b formed in the housing 35 so as to reach only the inside of the independent region L2 that is a generated magnetic field of the facing detection head 40 and extended from the generated magnetic field of the coaxial detection head 30. Thus, it is attached so as to be movable in the independent region L2. In the case where the opposed adjustment portion 52 is configured as a screw, the rotation of the opposed adjustment portion 52 moves forward and backward within the independent region L2.
[0032]
When adjusting the balance, first, the coaxial detection head 30 that forms the shared region L1 is applied, and the coaxial adjustment unit 51 is moved. The coaxial adjustment unit 51 changes the magnetic flux generated by the coaxial detection head 30 by the movement thereof, and obtains the balance of the induced voltages between the receiving coils 32 and 33. Next, the counter-type detection head 40 that forms the independent region L2 is applied and the counter-side adjustment unit 52 is moved. The counter-side adjustment unit 52 changes the magnetic flux generated by the counter-type detection head 40 by the movement, and obtains the balance of the induced voltage between the receiving coils 42 and 43.
[0033]
When the balance adjustment is performed and the balance of the induced voltages in the shared region L1 (coaxial detection head 30) is obtained, the coaxial adjustment unit 51 passes through the generated magnetic field of the opposed detection head 40. The magnetic flux of the head 40 is affected. However, when the balance of the induced voltages in the independent region L2 (opposing detection head 40) is obtained next, the independent region L2 is independent of the shared region L1, and therefore the magnetic flux of the coaxial detection head 30 is affected. There is no. Thereby, it is possible to obtain the balance of the induced voltages of the coaxial detection head 30 and the opposed detection head 40. Thus, according to the balance adjustment mechanism described above, it is possible to easily adjust the balance of the induced voltages of the detection heads 30 and 40.
[0034]
By the way, a change is given to the magnetic flux in the common area L1 (coaxial detection head 30 side) to change the magnetic flux in the coaxial side adjustment unit 51 that obtains a balance of the induced voltages by changing the magnetic flux in the shared area L1 (opposite detection head 40 side). The counter-side adjusting unit 52 that obtains the balance of the induced voltage is provided on the independent region L2 side. In addition, the independent region L2 is extended to a portion that is not involved in the examination space S through which the subject W is passed. In accordance with this configuration, a shield member 55 is provided between the magnetic field between the shared region L1 and the independent region L2 to shield between the magnetic field between the shared region L1 and the independent region L2 of the portion applied to each of the adjustment units 51 and 52. It has been. The shield member 55 is formed in a plate shape with a magnetic shield material such as a metal (for example, an aluminum alloy or stainless steel), like the casing 35. And it is provided in the housing | casing 35 so that each area | region L1, L2 may be divided | segmented.
[0035]
Thus, if the shield member 55 is provided, the independent region L2 is magnetically separated from the shared region L1, and therefore, when adjusting the balance between the regions L1 and L2, there is less influence on each other, making it easier. Adjustments can be made. Further, the shield member 55 can obtain the above-described effect even when the independent region L2 is a narrow range, and the metal detector having the above-described configuration can be downsized.
[0036]
Hereinafter, another balance adjustment mechanism will be described.
FIG. 3 is a perspective view showing another balance adjustment mechanism.
[0037]
As shown in FIG. 3, in the above-described metal detector, the generated magnetic field of the opposing detection head 40 (indicated by a one-dot chain line in FIG. 3) is the generated magnetic field of the coaxial detection head 30 (indicated by a two-dot chain line in FIG. 3). ) As a result, in the generated magnetic field of the opposed detection head 40, the portion that intersects the generated magnetic field of the coaxial detection head 30 forms a shared region L1 ′ where the generated magnetic fields of the coaxial detected head 30 and the opposed detection head 40 intersect. .
[0038]
In the coaxial detection head 30, the coils 31, 32 and 33 are extended to the right side in FIG. As a result, in the generated magnetic field of the coaxial detection head 30 (indicated by a two-dot chain line in FIG. 3), the portion extending to the region not affected by the generated magnetic field of the opposed detection head 40 is adjacent to the shared region L1 ′. L2 'is made.
[0039]
In the above configuration, the casing 35 is provided with adjusting portions 51 ′ and 52 ′. The adjusting portion is a metal rod made of a magnetic metal body (for example, iron) or a non-magnetic metal body (for example, aluminum alloy or stainless steel), and is preferably configured as a screw shown in FIG. The adjustment unit includes a coaxial adjustment unit (first adjustment unit) 51 ′ and a counter adjustment unit (second adjustment unit) 52 ′.
[0040]
The facing side adjustment unit 52 ′ is a recess formed in the casing 35 through the generated magnetic field of the coaxial detection head 30 that extends so as to reach the shared region L 1 ′ that is the generated magnetic field of the facing detection head 40. In 35a, it is attached so as to be movable in the shared area L1 ′. In the case where the facing adjustment portion 52 ′ is configured as a screw, the rotation thereof moves forward and backward within the shared region L1 ′.
[0041]
The coaxial adjustment portion 51 ′ is movable in the independent region L 2 ′ within the recess 35 b formed in the housing 35 so as to reach only the independent region L 2 ′ that is the generated magnetic field of the coaxial detection head 30. Attached. In the case where the coaxial adjustment portion 51 ′ is configured as a screw, it moves forward and backward within the independent region L2 ′ by its rotation.
[0042]
In adjusting the balance, first, the counter-type detection head 40 that forms the shared region L1 ′ is applied, and the counter-side adjustment unit 52 ′ is moved. The counter-side adjustment unit 52 ′ changes the magnetic flux generated by the counter-type detection head 40 by the movement, and obtains a balance of induced voltages between the receiving coils 42 and 43. Next, it is applied to the coaxial detection head 30 forming the independent region L2 ′, and the coaxial adjustment unit 51 ′ is moved. The coaxial adjustment unit 51 ′ changes the magnetic flux generated by the coaxial detection head 30 by the movement, and obtains a balance of the induced voltages between the receiving coils 32 and 33.
[0043]
When the balance adjustment is performed and the balance of the induced voltages in the shared region L1 ′ (opposing detection head 40) is obtained, the opposing adjustment unit 52 ′ passes through the generated magnetic field of the coaxial detection head 30, so that it is coaxial. This affects the magnetic flux of the mold detection head 30. However, when the induced voltage balance in the independent region L2 ′ (coaxial detection head 30) is obtained next, the independent region L2 ′ is independent of the shared region L1 ′, so that the magnetic flux of the opposed detection head 40 is affected. Never give. Thereby, it is possible to obtain the balance of the induced voltages of the coaxial detection head 30 and the opposed detection head 40. Thus, according to the balance adjustment mechanism described above, it is possible to easily adjust the balance of the induced voltages of the detection heads 30 and 40.
[0044]
By the way, it changes to the magnetic flux of the opposing side adjustment part 52 'which gives the change of the magnetic flux of shared area | region L1' (opposite type | mold detection head 40 side) and balances an induced voltage, and the independent area | region L2 (coaxial type detection head 30 side). Are provided on the independent region L2 ′ side. Further, the independent region L2 ′ is extended to a portion that is not involved in the examination space S through which the subject W is passed. According to this configuration, the magnetic field between the shared region L1 ′ and the independent region L2 ′ is shielded between the magnetic field between the shared region L1 ′ and the independent region L2 ′ of the portion applied to each of the adjustment units 51 ′ and 52 ′. A shield member 55 is provided. The shield member 55 is formed in a plate shape with a magnetic shield material such as a metal (for example, an aluminum alloy or stainless steel), like the casing 35. And it is provided in the housing | casing 35 so that each area | region L1 ', L2' may be divided | segmented.
[0045]
As described above, when the shield member 55 is provided, the independent region L2 ′ is magnetically separated from the shared region L1 ′. Therefore, when the balance between the regions L1 ′ and L2 ′ is adjusted, the mutual influence is reduced. Thus, adjustment can be performed more easily. In addition, the shield member 55 can obtain the above-described effect even when the independent region L2 ′ is in a narrow range, and the metal detector having the above-described configuration can be downsized.
[0046]
【The invention's effect】
As described above, the metal detector according to the present invention is shared by the shared area where the generated magnetic field of one detection head and the generated magnetic field of the other detection head intersect, and any of the generated magnetic fields is extended outside the shared area. Each region and an independent region adjacent to each other are obtained, and the balance of each region is individually adjusted by each adjustment unit. As a result, when the balance adjustment of the detection head in the common area is first performed, the magnetic flux of the detection head in the independent area is affected. However, in the balance adjustment of the detection head in the independent area, the magnetic flux of the detection head in the common area is affected. Therefore, the balance adjustment can be easily performed without adjusting the balance of the induced voltages of the two-axis and two-set detection heads.
[0047]
In addition, by providing a shield member that shields the magnetic field between the shared area and the independent area, the independent area is magnetically separated from the shared area, so that the mutual influence is reduced when adjusting the balance of each area. Thus, the adjustment can be performed more easily. Furthermore, since the above effect can be obtained by the shield member even if the independent region is a narrow range, the metal detector having the above configuration can be downsized.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a detection head of a metal detector of the present invention.
FIG. 2 is a perspective view showing a balance adjustment mechanism.
FIG. 3 is a perspective view showing another balance adjustment mechanism.
FIG. 4 is a schematic view showing a detection head of a conventional metal detector.
FIG. 5 is a perspective view showing a conventional balance adjustment mechanism.
FIG. 6 is a schematic view showing two pairs of detection heads;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 30 ... Coaxial type detection head (one detection head), 32 ... Reception coil, 33 ... Reception coil, 40 ... Opposite type detection head (the other detection head), 42 ... Reception coil, 43 ... Reception coil, 51 ... Coaxial side Adjustment unit (first adjustment unit), 51 '... Coaxial side adjustment unit (first adjustment unit), 52 ... Opposite side adjustment unit (second adjustment unit), 52' ... Opposite side adjustment unit (second adjustment unit), 55 ... Shield member, L1 ... Shared area, L1 '... Shared area, L2 ... Independent area, L2' ... Independent area.

Claims

A metal detector having both detection heads (30, 40) that generate two perpendicular magnetic fields in an inspection space (S) in which an object to be inspected (W) is conveyed,
A common region (L1 (L1 ′)) where the generated magnetic fields of the one detection head and the other detection head intersect;
An independent region (L2 (L2 ′)) in which the generated magnetic field of either the one detection head or the other detection head extends outside the common region and is adjacent to the common region;
An adjustment unit (51 (52 ′) arranged in the shared area to balance the induced voltage of each of the receiving coils (32, 33 (42, 43)) of either one of the one detection head or the other detection head. ))When,
An adjustment unit (52 (51 ′) arranged in the independent region to balance the induced voltage of each of the other reception coils (42, 43 (32, 33)) of the one detection head or the other detection head ))When,
A metal detector characterized by comprising:

Each adjustment part (51, 52 (51 ′, 52 ′)) is arranged in a part not related to the examination space (S), and the shared region (L1 (L1 ′)) of the part related to each adjustment part The metal detector according to claim 1, further comprising a shield member (55) that shields a magnetic field between the magnetic field and the independent region (L2 (L2 ')).

A method for adjusting a balance of a metal detector having both detection heads (30, 40) that generate biaxial magnetic fields orthogonal to each other in an inspection space (S) in which an object to be inspected (W) is conveyed,
Each receiving coil (32) of either the one detection head or the other detection head in a common region (L1 (L1 ′)) where the generated magnetic fields of the one detection head and the other detection head intersect. , 33 (42, 43)), the generated magnetic field of either one of the one detection head or the other detection head extends to the outside of the shared area and is adjacent to the shared area. In the independent region (L2 (L2 ′)), the balance of the induced voltages of the receiving coils (42, 43 (32, 33)) of either the one detection head or the other detection head is obtained. A method for adjusting the balance of a metal detector.