JP4511086B2

JP4511086B2 - Metal detector

Info

Publication number: JP4511086B2
Application number: JP2001279899A
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: 2010-07-28
Anticipated expiration: 2021-09-14
Also published as: JP2003084071A

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３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３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３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３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４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４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５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５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５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、
薄板状の磁性体からなり、前記一方の検出ヘッド３０が発生する磁束に平行に配置されて前記一方の検出ヘッド３０の磁束に対して移動可能とされた第一調整部材１１と、
薄板状の非磁性体からなり、前記一方の検出ヘッド３０が発生する磁束に直交するように配置されて前記一方の検出ヘッド３０の磁束に対して移動可能とされた第二調整部材１２と、
薄板状の磁性体からなり、前記他方の検出ヘッド４０が発生する磁束に平行に配置されて前記他方の検出ヘッド４０の磁束に対して移動可能とされた第三調整部材１３と、
薄板状の非磁性体からなり、前記他方の検出ヘッド４０が発生する磁束に直交するように配置されて前記他方の検出ヘッド４０の磁束に対して移動可能とされた第四調整部材１４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、
前記第一調整部材１１、前記第二調整部材１２、前記第三調整部材１３および前記第四調整部材１４は、それぞれ前記移動方向に移動可能とされた磁界に影響を及ぼさない直方形状の各支持部材２０に対して取り付けられていることを特徴とする。
【００１４】
【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、図２はバランス調整機構を示す斜視図である。
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。
【００１５】
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。
【００１６】
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５参照）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。
【００１７】
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５参照）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。
【００１８】
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。
【００１９】
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。
【００２０】
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。
【００２１】
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。
【００２２】
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。
【００２３】
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。
【００２４】
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。
【００２５】
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。バランス調整機構は、図１および図２に示すように、第一調整部材１１と、第二調整部材１２と、第三調整部材１３と、第四調整部材１４とを有している。
【００２６】
第一調整部材１１および第三調整部材１３は、薄板状の磁性金属体（例えば鉄）からなる。第二調整部材１２および第四調整部材１４は、薄板状の非磁性金属体（例えばアルミ合金やステンレス鋼など）からなる。各調整部材１１，１２，１３，１４は、それぞれ各支持部材２０に取り付けられている。各支持部材２０は、磁界に影響を及ぼさない電磁気に対する透明体である例えば合成樹脂材を直方形状に成形してなる。
【００２７】
第一調整部材１１は、同軸型検出ヘッド３０が発生する図１中左右方向（図５参照）の磁束に平行となるように、支持部材２０の上面に取り付けられている。また、第二調整部材１２は、同軸型検出ヘッド３０が発生する図１中左右方向（図５参照）の磁束に直交するように、支持部材２０の側面に取り付けられている。また、第三調整部材１３は、対向型検出ヘッド３０が発生する図１中上下方向（図５参照）の磁束に平行となるように、支持部材２０の側面に取り付けられている。また、第四調整部材１４は、対向型検出ヘッド３０が発生する図１中上下方向（図５参照）の磁束に直交するように、支持部材２０の上面に取り付けられている。これにより、各調整部材１１，１２，１３，１４の各検出ヘッド３０，４０の磁束に対する上記配置を容易に得ることが可能である。
【００２８】
各調整部材１１，１２，１３，１４が取り付けられた各支持部材２０は、それぞれ筐体３５の底面の凹部３５ａ内に収容固定される基台２１上に配設されている。各支持部材２０は、図２に示すように、基台２１に立設された固定片２１ａに回転自在に設けられた各調整ネジ２２が螺合されることにより、それぞれ調整ネジ２２の回転に際して基台２１上を移動する。すなわち、各調整部材１１，１２は、各調整ネジ２２の回転により同軸型検出ヘッド３０の磁束に対して移動可能とされ、各調整部材１３，１４は、各調整ネジ２２の回転により対向型検出ヘッド４０の磁束に対して移動可能とされている。なお、基台２１、固定片２１ａおよび調整ネジ２２は、支持部材２０と同様に磁界に影響を及ぼさない電磁気に対する透明体である例えば合成樹脂材からなる。
【００２９】
バランス調整に際しては、例えば、最初に同軸型検出ヘッド３０にかかり、各調整部材１１，１２を移動させる。次いで対向型検出ヘッド４０にかかり、各調整部材１３，１４を移動させる。
【００３０】
同軸型検出ヘッド３０の磁束に平行する磁性金属体である第一調整部材１１は、その移動により同軸型検出ヘッド３０の磁束に対して変化を与えるが、対向型検出ヘッド４０の磁束に直交するので大きな変化を与えない。さらに、同軸型検出ヘッド３０の磁束に直交する非磁性金属体である第二調整部材１２は、その移動により同軸型検出ヘッド３０の磁束に対して変化を与えるが、対向型検出ヘッド４０の磁束に平行するので大きな変化を与えない。これにより、各調整部材１１，１２を移動させた場合には、同軸型検出ヘッド３０のみのバランス調整が行われて対向型検出ヘッド４０の磁束に影響を与えずに同軸型検出ヘッド３０の誘起電圧の平衡を得ることが可能である。
【００３１】
また、対向型検出ヘッド４０の磁束に平行する磁性金属体である第三調整部材１３は、その移動により対向型検出ヘッド４０の磁束に対して変化を与えるが、同軸型検出ヘッド３０の磁束に直交するので大きな変化を与えない。さらに、対向型検出ヘッド４０の磁束に直交する非磁性金属体である第四調整部材１４は、その移動により対向型検出ヘッド４０の磁束に対して変化を与えるが、同軸型検出ヘッド３０の磁束に平行するので大きな変化を与えない。これにより、各調整部材１３，１４を移動させた場合には、対向型検出ヘッド４０のみのバランス調整が行われて同軸型検出ヘッド３０の磁束に影響を与えずに対向型検出ヘッド４０の誘起電圧の平衡を得ることが可能である。
【００３２】
なお、各検出ヘッド３０，４０のバランス調整にかかり、各調整部材１１，１２，１３，１４全てを移動させる必要はなく、適した各調整部材１１，１２，１３，１４を選択して移動させればよい。
【００３３】
また、上述した実施の形態では、各調整部材１１，１２，１３，１４が取り付けられた各支持部材２０を移動させる構成は、上述の構成に限らず、例えば、図示しないが各支持部材２０を基台２１に設けた長穴あるいは大穴を介してネジ固定し、ネジを緩めて移動させるなど様々な構成が考えられる。
【００３４】
【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磁束に平行する磁性体である第一調整部材と、一方の検出ヘッドの磁束に直交する非磁体である第二調整部材の移動により、他方の検出ヘッドの磁束に影響を与えずに一方の検出ヘッドのみのバランス調整が行われる。また、他方の検出ヘッドの磁束に平行する磁性体である第三調整部材と、他方の検出ヘッドの磁束に直交する非磁体である第四調整部材の移動により、一方の検出ヘッドの磁束に影響を与えずに他方の検出ヘッドのみのバランス調整が行われる。これにより、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。
【００３５】
また、第一調整部材、第二調整部材、第三調整部材および第四調整部材を、移動可能とされた磁界に影響を及ぼさない各支持部材に対して取り付ければ、各調整部材の各検出ヘッドの磁束に対する上記配置を容易に得ることができる。
【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】従来の金属検出機の検出ヘッドを示す概略図。
【図４】従来のバランス調整機構を示す斜視図。
【図５】二軸二組の検出ヘッドを示す概略図。
【符号の説明】
１１…第一調整部材、１２…第二調整部材、１３…第三調整部材、１４…第四調整部材、２０…支持部材、３０…同軸型検出ヘッド（一方の検出ヘッド）、３１…送信コイル、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）、４１…送信コイル、４２…受信コイル、４３…受信コイル。[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. 3 is a diagram showing the detection principle of the detection head in the metal detector. As shown in FIG. 3, 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. 3). 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. 3 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 increases. 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. As shown in FIG. 4, in the conventional balance adjustment, 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. 5, 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. 5, the detection head 40 has, for example, a transmission coil 41 disposed above the detection head 30, and adjacent reception coils 42 and 43 disposed 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. 3). 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. 5, the detection head 30 generates a magnetic flux in the horizontal 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 pair of detection heads in two axes. It is intended to provide.
[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 first adjusting member 11 made of a thin plate-like magnetic body, arranged in parallel with the magnetic flux generated by the one detection head 30 and movable with respect to the magnetic flux of the one detection head 30;
A second adjustment member 12 made of a thin non-magnetic material, arranged so as to be orthogonal to the magnetic flux generated by the one detection head 30, and movable with respect to the magnetic flux of the one detection head 30;
A third adjusting member 13 made of a thin plate-like magnetic body, arranged in parallel with the magnetic flux generated by the other detection head 40, and movable with respect to the magnetic flux of the other detection head 40;
A fourth adjusting member 14 made of a thin non-magnetic material, arranged so as to be orthogonal to the magnetic flux generated by the other detection head 40, and movable with respect to the magnetic flux of the other detection head 40;
It is provided with.
[0013]
The metal detector according to claim 2 is the metal detector according to claim 1,
The first adjustment member 11, the second adjustment member 12, the third adjustment member 13, and the fourth adjustment member 14 are each a rectangular support that does not affect the magnetic field that is movable in the movement direction. It is attached to the member 20.
[0014]
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, and FIG. 2 is a perspective view showing a balance adjusting mechanism.
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.
[0015]
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.
[0016]
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. 5) 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.
[0017]
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. The counter-type detection head 40 generates a magnetic flux in the vertical direction in FIG. 1 (see FIG. 5) by the alternating magnetic field of the transmission coil 41 in the inspection space S, so that the phase is applied to 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.
[0018]
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.
[0019]
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.
[0020]
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.
[0021]
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.
[0022]
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.
[0023]
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.
[0024]
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.
[0025]
The metal detector of the present embodiment includes the following balance adjustment mechanism. As shown in FIGS. 1 and 2, the balance adjustment mechanism includes a first adjustment member 11, a second adjustment member 12, a third adjustment member 13, and a fourth adjustment member 14.
[0026]
The first adjustment member 11 and the third adjustment member 13 are made of a thin plate-like magnetic metal body (for example, iron). The 2nd adjustment member 12 and the 4th adjustment member 14 consist of a thin plate-like nonmagnetic metal body (for example, aluminum alloy, stainless steel, etc.). Each adjustment member 11, 12, 13, 14 is attached to each support member 20. Each support member 20 is formed by molding, for example, a synthetic resin material in a rectangular shape, which is a transparent body against electromagnetism that does not affect the magnetic field.
[0027]
The first adjustment member 11 is attached to the upper surface of the support member 20 so as to be parallel to the magnetic flux generated in the left-right direction in FIG. 1 (see FIG. 5) generated by the coaxial detection head 30. The second adjustment member 12 is attached to the side surface of the support member 20 so as to be orthogonal to the magnetic flux in the left-right direction in FIG. 1 (see FIG. 5) generated by the coaxial detection head 30. The third adjustment member 13 is attached to the side surface of the support member 20 so as to be parallel to the magnetic flux generated in the up-down direction in FIG. 1 (see FIG. 5) generated by the opposed detection head 30. Further, the fourth adjustment member 14 is attached to the upper surface of the support member 20 so as to be orthogonal to the magnetic flux in the vertical direction in FIG. 1 (see FIG. 5) generated by the opposed detection head 30. Thereby, the said arrangement | positioning with respect to the magnetic flux of each detection head 30,40 of each adjustment member 11,12,13,14 can be obtained easily.
[0028]
Each support member 20 to which each adjustment member 11, 12, 13, 14 is attached is disposed on a base 21 that is housed and fixed in a recess 35 a on the bottom surface of the housing 35. As shown in FIG. 2, each supporting member 20 is engaged with a fixing piece 21 a erected on a base 21 by being screwed with an adjusting screw 22 that is rotatably provided. Move on the base 21. That is, the adjustment members 11 and 12 are movable with respect to the magnetic flux of the coaxial detection head 30 by the rotation of the adjustment screws 22, and the adjustment members 13 and 14 are opposed to each other by the rotation of the adjustment screws 22. The head 40 is movable with respect to the magnetic flux. The base 21, the fixing piece 21 a, and the adjustment screw 22 are made of, for example, a synthetic resin material that is an electromagnetic transparent body that does not affect the magnetic field, like the support member 20.
[0029]
In the balance adjustment, for example, first, the coaxial detection head 30 is applied, and the adjustment members 11 and 12 are moved. Next, the opposing detection head 40 is moved to move the adjusting members 13 and 14.
[0030]
The first adjusting member 11, which is a magnetic metal body parallel to the magnetic flux of the coaxial detection head 30, changes the magnetic flux of the coaxial detection head 30 by its movement, but is orthogonal to the magnetic flux of the opposing detection head 40. So do not give a big change. Further, the second adjusting member 12, which is a nonmagnetic metal body orthogonal to the magnetic flux of the coaxial detection head 30, changes the magnetic flux of the coaxial detection head 30 by its movement, but the magnetic flux of the opposed detection head 40. It does not give a big change. As a result, when the adjustment members 11 and 12 are moved, only the coaxial detection head 30 is adjusted in balance, and the coaxial detection head 30 is induced without affecting the magnetic flux of the opposed detection head 40. It is possible to obtain a voltage balance.
[0031]
Further, the third adjusting member 13, which is a magnetic metal body parallel to the magnetic flux of the opposed detection head 40, changes the magnetic flux of the opposed detection head 40 due to its movement. Because it is orthogonal, it does not give a big change. Further, the fourth adjusting member 14, which is a nonmagnetic metal body orthogonal to the magnetic flux of the opposed detection head 40, changes the magnetic flux of the opposed detection head 40 due to its movement, but the magnetic flux of the coaxial detection head 30. It does not give a big change. As a result, when the adjustment members 13 and 14 are moved, only the counter-type detection head 40 is adjusted in balance, and the counter-type detection head 40 is induced without affecting the magnetic flux of the coaxial type detection head 30. It is possible to obtain a voltage balance.
[0032]
Note that it is not necessary to move all the adjustment members 11, 12, 13, and 14 for the balance adjustment of the detection heads 30 and 40, and the appropriate adjustment members 11, 12, 13, and 14 are selected and moved. Just do it.
[0033]
Moreover, in embodiment mentioned above, the structure which moves each support member 20 to which each adjustment member 11,12,13,14 was attached is not restricted to the above-mentioned structure, For example, although not shown, each support member 20 is not shown. Various configurations are conceivable, such as fixing with screws through long holes or large holes provided in the base 21 and moving the screws by loosening them.
[0034]
【The invention's effect】
As described above, the metal detector according to the present invention includes a first adjustment member that is a magnetic body parallel to the magnetic flux of one detection head and a second adjustment member that is a non-magnetic body orthogonal to the magnetic flux of one detection head. By the movement, the balance adjustment of only one detection head is performed without affecting the magnetic flux of the other detection head. Further, the movement of the third adjustment member, which is a magnetic body parallel to the magnetic flux of the other detection head, and the fourth adjustment member, which is a non-magnetic body orthogonal to the magnetic flux of the other detection head, affect the magnetic flux of one detection head. The balance adjustment of only the other detection head is performed without giving any value. Thereby, it is possible to easily adjust the balance of the induced voltages of the two-axis and two-set detection heads.
[0035]
Further, if the first adjustment member, the second adjustment member, the third adjustment member, and the fourth adjustment member are attached to each support member that does not affect the movable magnetic field, each detection head of each adjustment member The above arrangement with respect to the magnetic flux can be easily obtained.
[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 schematic view showing a detection head of a conventional metal detector.
FIG. 4 is a perspective view showing a conventional balance adjustment mechanism.
FIG. 5 is a schematic view showing two pairs of detection heads;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... 1st adjustment member, 12 ... 2nd adjustment member, 13 ... 3rd adjustment member, 14 ... 4th adjustment member, 20 ... Support member, 30 ... Coaxial type detection head (one detection head), 31 ... Transmission coil , 32... Reception coil, 33... Reception coil, 40... Opposing detection head (the other detection head), 41... Transmission coil, 42.

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 first adjusting member (11) made of a thin plate-like magnetic body, arranged in parallel to the magnetic flux generated by the one detection head and movable with respect to the magnetic flux of the one detection head;
A second adjusting member (12) made of a thin non-magnetic material, arranged so as to be orthogonal to the magnetic flux generated by the one detection head, and movable with respect to the magnetic flux of the one detection head;
A third adjustment member (13) made of a thin plate-like magnetic body, arranged in parallel with the magnetic flux generated by the other detection head, and movable with respect to the magnetic flux of the other detection head;
A fourth adjustment member (14) made of a thin non-magnetic material, arranged so as to be orthogonal to the magnetic flux generated by the other detection head, and movable with respect to the magnetic flux of the other detection head;
A metal detector characterized by comprising:

The first adjusting member (11), the second adjusting member (12), the third adjusting member (13), and the fourth adjusting member (14) each affect a magnetic field that is movable in the moving direction. The metal detector according to claim 1, wherein the metal detector is attached to each support member (20) that does not affect the metal.