JP2004008862A - Contamination propagation-preventing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently and certainly prevent a propagation of contamination in the case where unexpected contamination grows particularly in a cleaning area of a small sized manufacturing system. <P>SOLUTION: In the manufacturing system 1 in which a plurality of local cleaning devices 3 for carrying out a predetermined manufacturing step such as assembling, processing or the like of a workpiece 2 is connected by a tubular connection passage 4 to form a cleaning area C and a series of cleaning manufacturing step is realized, the system for preventing the propagation of contamination is applied. In the contamination propagation-preventing system 1, at least either one of a contamination occurrence detection means for detecting contamination generating at the cleaning area C in the system or a contamination occurrence prediction means for predicting occurrence of the contamination; a contamination propagation prediction means for predicting propagation of the generated contamination to the other local cleaning device 3; and a contamination propagation prevention means for preventing propagation of the generated contamination to the other local cleaning device 3 are provided on the local cleaning device 3 or the connection passage 4. <P>COPYRIGHT: (C)2004,JPO

Description

【００２３】
２．汚染ワークのマーキング
続いて、製造システムの各モジュール３の内部において汚染されたワーク２が生じた場合に、かかる汚染ワーク２を如何にマーキングし汚染伝播を防止するかについて説明する（図１参照）。なお図１に示す製造システムでは図中左側（上流側）から右側（下流側）へワーク２を搬送するものとし、左側から５番目のモジュール３内で汚染が発生した場合を示している。符号Ａ１が示す楕円形状域は処置が完了するまでに汚染される領域、符号Ａ２が示す白抜きの楕円形状域は処置完了までに汚染伝播が懸念される領域を示している。
【００２４】
上述の検出・予知によりワーク２の汚染可能性があると判断した場合、不良品を製造しても意味が無いことに加え、更に重要な問題として汚染粒子が下流工程の治工具類に転写されてしまう事を避けるため、汚染可能性があるワーク２にマーキングを行い、排出可能な所へ搬送して排出することが望ましい。例えば本実施形態の場合、自走式ワーク搬送パレットとワーク載置部の双方に記憶機能を備え付けたことから、汚染可能性がある旨を自走式ワーク搬送パレットもしくはワーク載置部に記憶をさせ排出可能な地点まで経由する工程においてこの記憶状態を読み出し、ワーク２に触れない様に制御する処置をする。また、汚染が検出または予測されたモジュール３内に存在したワーク２及び当該モジュール３から上流側または下流側に順次接続される所定数のモジュール３内または接続路４内に存在したワーク２の排出を行う。また、ワーク２の排出が可能な地点において、当該ワーク２を排出し廃棄する一方で、ワーク載置部は洗浄を行った後に再度使用することが好ましい。記憶されている汚染可能性有の記憶は廃棄が行われるこの時点で汚染可能性無に書き換えられる。なお、ワーク２を排出する代わりにワーク載置部と同様に洗浄して再度使用することも可能である。
【００２５】
３．汚染ワークの特定
汚染の予知、検出が行われたモジュール３及びその近傍のワーク２は前述の如くマーキングされ不良品とするが、その下流側にあり汚染伝播が防止される範囲内のワーク２に関しては組み立ての続行が可能である。また上流側では一時的に、即ち正常な生産加工が再開されるまで待機する事で無駄なく生産を継続する事ができる。またファン１６の異常による「停止」の場合、予知されたときから実際に汚染されるまでの時間は長く、検出直後のワーク２が汚染される事はない。この場合はある一定時間後に当該工程へのワーク２の搬入を中止するといった処理を行う事で効率の良い生産が維持できる。汚染がどの程度伝播するかは、製造システムにおけるクリーン度を保つための構造、伝播防止方法、検出予測方法とそれらの時間によってある程度決定する。
【００２６】
ここで、「汚染」のケースとしてタバコの煙を清浄領域Ｃ内にストロー１５で導入した場合の汚染の調査結果を示す（図４参照）。ここでは喫煙後５〜６秒の息を自走式ワーク搬送パレットの停止位置を中心に吹き込んでいる。この場合、径が０．３μｍ程度の汚染粒子が約２３００ヶ検出された。また、それから３０秒後の時点で、当該モジュール３内の粒子は３０ヶまで減少し、かつその隣のモジュール３内において２００ヶ程度の粒子が検出された。この結果、タバコの煙はダウンフローによりその殆どは小孔を備えた隔壁９の下方に排気され密度は１／１０程度になるものの、隣の清浄領域Ｃへの伝播があることが確認された。なお、このとき実際にはレール形状との相関が大きく、レール下面がグレーティング状になっていると伝播量は激減することも確認できた。また、自走式ワーク搬送パレットの移動による伝播も観測され、この自走式ワーク搬送パレットが煙粒子を巻き込みながら進行するため、下流側においても大量の粒子が観測された。
【００２７】
さらに、「破壊」のケースを想定して実施したテスト結果についても説明する（図５参照）。このテストは、接続されたモジュール３の片側の扉１８を開放した状態で評価することによって行ったものである。汚染の状況は開放の面積の広さ、高さに大きく依存する。ここでは、図５に示すように、モジュール３の側壁に、清浄領域１７０×２３０×２００［ｍｍ］に対し５０×８０［ｍｍ］程度の開口部を設けた。この場合、清浄度の悪化は全く起こらなかった。更に、図６に示すように前面扉１８の完全開放として開口面積を広げた場合、開放側では１００００ヶ以上、隣のモジュール３においては２０ヶ程度の粒子が観測され、殆ど影響を受けていない事がわかった。
【００２８】
これらの実験を通して他にも、下記の結論が得られた。すなわち、
（１）上部フィルタ１７からワーク２の搬送面までに至る清浄領域Ｃ内の封止（シール）が完全であれば（あるいはこれに近い状態であれば）外気との差圧と清浄度の相関関係は低い。
（２）清浄空気の流速及びそのベクトルの方向が非常に重要で汚染環境に対して負の方向の流れが維持されている事が重要である。
（３）汚染の拡張そのものの速度は非常に遅く、流速ベクトルの大きさは速い必要はない。
【００２９】
なお、ここでいう「負の方向」は、清浄環境から汚染環境へ流れ込む方向をいい、正の方向はこれとは逆に汚染環境から清浄環境へ流れ出る方向をいう（図７参照）。また、（３）の結論は前面扉１８の完全開放の状態で開放側のファン１６を停止させ、その後に隣もモジュール３のファン１６を停止させた後、３０秒以上立ってから粒子のカウントが始まった事実を基に判断したものである。
【００３０】
ここまでの結論として観測に対してどこまでワーク２が汚染されるかの問題として、仮に１０秒以内に対処ができる前提で考えると、各検出、予知に対して以下のような汚染の広がりを仮定する事ができる。
【００３１】
▲１▼パーティクルカウンタによる汚染の検出の場合
検出された当該モジュール３内のワーク２が汚染されていると判断しなければならない。実験では両隣の汚染の可能性は無いと判断できるが後述する流速ベクトルとの関係より、伝播はほぼ確実に判断できる。
【００３２】
▲２▼差圧減少による汚染の予知
差圧の減少が確認されても汚染は短時間では発生しない。よってモジュール３内の工程の時間が例えば３０秒以下であれば良品と考えても差し支えない。ただし、差圧の減少は接続されているモジュール３でほぼ同時に発生する可能性が高く差圧減少だけが検出された場合原因となったモジュール３を特定する事は困難であり、時間がかかる為３０秒内に回復を行う事は困難であり、検出予知の方法として差圧検出だけを用いる事は望ましくない。
【００３３】
▲３▼流速・方向による汚染の予知
流速とその方向が大まかにでも計測可能である場合は汚染の広がりをかなり正確に推定することができる。本実施形態のような自走式ワーク搬送パレットを用いた製造システムの場合、汚染が伝播して行く経路は接続路４だけであり、汚染粒子の拡散速度は、風速に対して非常に遅い速度であると考えられるためである。即ち、自走式ワーク搬送パレットの移動を考慮しない場合、汚染は接続路４内を通る空気を媒体にしてのみ移動すると考えられ、接続路４の空気の移動を検出する事は清浄度維持に対して非常に重要であるといえる。汚染が検出されたモジュール３に対して流速ベクトルが排出方向に検出されている場合は汚染は伝播したと判断して良い。
【００３４】
４．非汚染ワークの救済
汚染可能性のあるワーク２に対しての処理は後述する伝播の遮断方法とも関連するが、基本的には汚染を伝播する可能性のあるワーク２は全て不良品として排出し、廃棄もしくは再度洗浄し再投入するようにする。一方、汚染が検出または予測されたモジュール３から下流側に順次接続される所定数のモジュール３より更に下流の工程に存在するワーク２の製造は続行し、汚染が検出または予測されたモジュール３及び当該モジュール３から上流側に順次接続される所定のモジュール３内のワーク２の製造を中断するようにしている。つまり、伝播の可能性が無いと判断されたものに関しては汚染可能性が無い範囲までは通常の生産作業が続行されるようにしている。そして、当該工程（汚染可能性がある工程：複数の場合も含める）の上流の工程では当該工程までの生産を継続し、当該工程の直前工程で生産及び搬送を中断する。下流においては当該工程からの投入を行わないようにし、順次各工程は投入待ちの状態で作業が自動的に停止され、ワーク２を送り出した後の状態で待機する。このような制御により、汚染の可能性の無いワーク２に廃棄品が出ないように制御をする事が可能である。
【００３５】
なお、レールが複雑に組み合わされているような場合、自走式ワーク搬送パレットによるワーク２の搬送は単純に上流、下流では考えられない場合も多く、配膳供給と組み合わせた場合ワーク２がずれながら組み立てが実行されるケースも有るため、更に複雑な状況となるが基本は装置順でなく、工程図に沿った上流、下流と考えるものとする。
【００３６】
５．流速ベクトルの検出
ここまで述べてきたように流速の検出は汚染伝播を推定する上で有効な手段であると言える。本実施形態のように局所的に清浄領域Ｃが形成されたモジュール３が接続された製造システムにおいては、前述したように差圧の減少の検出が汚染と短時間ではすぐに結びつない。また扉１８が開いた事は検出できても、どのモジュール３の扉１８かを特定する事が困難である。この事より従来のクリーンルームでよく用いられる差圧検出は不向きであり、流速ベクトルの検出が有効な手段であるといえる。接続路４の流速の検出を行う事で、汚染伝播の推定だけでなくその他重要な清浄度管理に関わる問題を把握する事ができる。
【００３７】
▲１▼接続路４において全て負方向のベクトルが検出された場合
１つのモジュール３に接続される接続路４の流速ベクトルが負の方向に大きく変化したときには外気と直接的に接続されたと判断できる。ここでいう「直接的な接続」には例えばメンテナンス用の扉１８が開いた事等が含まれる。このような判断がなされた場合、汚染が発生した可能性が非常に高く、パーティクルモニタのようにある程度局所的な計測しか行えないものに対してモジュール３の清浄領域Ｃ全体が確認可能である。また、ファン１６の停止でも同様の状況が起こる。但し、扉１８の開放に比較し流速ベクトルの変動の速度は遅い。ファン１６の停止検出はコストも多くは必要としないため別途検出器を持った方が良いがベクトル変動検出でも検出はできる。
【００３８】
▲２▼接続路４において全て正方向のベクトルが検出された場合
後述する伝播の遮断動作が確実に行われている事がモニタできる。
【００３９】
▲３▼接続路４において負方向と正方向のベクトルが検出された場合
負方向の接続路４からは汚染が伝播されている可能性がある。従って、その接続路４に接続されるモジュール３の判定状況を確認し汚染を判断しなければならない。このケースでは汚染の伝播は流速ベクトルの大きさに比例すると考えられる。
【００４０】
この様な汚染のモニタリングとは別に接続路４の流速ベクトルをモニタできる事は清浄度設計、即ち汚染発生が多いかまたは懸念されるモジュール３や汚染を嫌う工程の個別空気管理に威力を発揮する。本実施形態の製造システムにおいては清浄度管理の単位をモジュール３に割り当てることが容易である（モジュール単位でファン１６と下部排気ファン１９を有しているため差圧と流量を独立に管理できる）。しかしながら個別のモジュール３の空気管理を行っても接続路４により接続された状態では差圧が全て一定となってしまい汚染粒子の方向は把握できない事となってしまう。ここまで述べてきたように汚染粒子は接続路４を伝播して移動するので、汚染伝播を予め所望通り設定する事ができる。
【００４１】
接続路４における流速ベクトルを検出するセンサとしては、例えば図８に示すような抵抗発熱体２１、サーミスタ２２、断熱基板２３、直流電源２４等からなる温度センサ２０を利用することができる。
【００４２】
６．汚染伝播の防止
本実施形態では汚染が発生した場合に清浄なモジュール３にまで汚染が伝播するのを防止する汚染伝播防止手段が設けられている。汚染伝播防止手段は、例えば汚染が検出または予測されたモジュール３とそのモジュール３に接続される接続路４の空気の流速、流れの方向の情報に基づいて、当該接続路４に接続するモジュール３に設けられた清浄空気発生手段を制御する手段によって構成されるが、これに限らず、例えば以下のａ）〜ｄ）のような手法によっても実現できる。
▲１▼接続路４の機械的な遮断
ａ）機械的シャッタの取り付け
機械的遮断においては機械可動部を持つため、それ自体が汚染源となる可能性も有り、即時の伝播防止には問題は残るが長期間の遮断を行う場合には有効な方法である。
【００４３】
ｂ）風船状のものを膨らませる事による遮断
風船上のものを膨らませる遮断方法は可動部による汚染の発生を防止できるが、実際には膨らませるために空圧源が必要である。
【００４４】
▲２▼空気の流れの制御による遮断
ｃ）流速ベクトルを汚染伝播の上流に向かうように発生させる制御
流速ベクトルの制御は即時の遮断には最も有功であることは以上の実施形態より明らかである。この場合、単純に汚染源と推定されたモジュール３のファン１６を停止させるか、もしくは排気手段である排気ファン１９の回転速度を上げるようにする（両方行っても良い）。緊急にマニュアルで行いたい場合は単純に汚染源の扉１８をある一定量開くといった方式で実現できる。また図９に示すように、各モジュール３のファン１６、排気ファン１９および流速センサ２０と接続されたコンピュータからなるモニタシステム２５を用いた場合、汚染が発生してからどの程度の時間で遮断の為の流速ベクトルが得られたか等の情報も取得しログする（登録する）事が可能となる。
【００４５】
ｄ）汚染伝播に対して直角方向に空気流を発生させる制御（図１０参照）
ｄ）の接続路４に直角の空気流を発生させる方法は汚染検出、予知時空気流を制御する方法とすることもできるがｃ）とは異なり、空気制御中もこの空気を流しても問題はなく常時、汚染の伝播が遮断されている状態が実現できる。直角方向の空気流により、常時汚染の伝播が遮断された状態が実現できる。ファン２６とフィルタ２７は、接続路４内の圧力が陽圧に保てない場合に設けられる。また、２つのモジュール３間の空気の行き来を遮断する場合には接続路４に排気ファン２８が設けられる。
【００４６】
７．回復
さらに汚染伝播防止システム１は、汚染検出または予測されたモジュール３または接続路４の清浄度を回復するための清浄度回復手段を有している。清浄度回復手段は、例えば清浄空気発生手段（ファン１６とフィルタ１７）と排気手段（排気ファン１９）とからなり、汚染の伝播防止が、汚染が検出または予測されたモジュール３とそのモジュール３に接続される接続路４の空気の流速、流れの方向の情報に基づいて、当該接続路４に接続するモジュール３に設けられた清浄空気発生手段からの清浄空気の流量を減少することにより行われるとともに、清浄度の回復は、清浄空気発生手段からの減少された清浄空気の流量を、清浄領域Ｃの清浄度を確保するために必要な流量まで次第に増加することにより行うものである。
【００４７】
なお、汚染の予知検出、伝播の予知、伝播の遮断が実行された後は、汚染源の特定と対策を行うことが望ましい。これが終了した後、汚染されたモジュール３の清浄化を行い、伝播遮断の解除の手段がとられる。原因が除去された後は拭き掃除などが実施された後に内部清浄領域Ｃの閉鎖がなされ清浄化される。単モジュール３での清浄化は内部清浄領域Ｃが小さい事によりファン１６の動作開始後２０〜３０秒で行われる。また、汚染伝播の遮断措置として、汚染モジュール３のファン１６の停止による接続路４からの流入により被接続のモジュール３への伝播が遮断されている場合、汚染されたモジュール３の清浄度回復のためにファン１６の動作により塵埃が隣のモジュール３、すなわち汚染の無いモジュール３へ伝播してしまう事となる。
【００４８】
つまり、図１１に示す遮断状態においては非汚染モジュール３から汚染モジュール３へと流れる空気が汚染伝播を防止しうるが、このとき汚染モジュール３において急にファン１６を回転させると、図１２に示すように急激なダウンフローが生じ、汚染が解消されないうちに汚染が非汚染モジュール３側へと流れ込んでしまうおそれがある。このような問題に対しては、以下の２段階の制御をファン１６に対して行う事で周囲に接続されたモジュール３に対し汚染の伝播をさせずに汚染モジュール３の回復が行える（図１３参照）。
▲１▼約２５秒かけて徐々にファン１６の回転速度を設定値まで上げて行く。
▲２▼設定値で１０秒待つ。
【００４９】
▲１▼の段階で既に汚染はほとんど回復されているが清浄化の条件が安定するまで（空気の流れ通常状態になる）▲２▼で待つ事になる。▲１▼の時間が余りに短いと周囲への汚染伝播が発生するが、長い分には回復の時間がかかるだけであり、このケースの生産性をあまり問題としない場合には、できる限りの時間をかけてゆっくりと立ち上げれば良い。
【００５０】
８．まとめ
ここまで述べてきた制御をまとめると下記のようになる。
汚染の発生検出
↓
伝播推定
↓
伝播遮断
↓
対策処理
↓
回復
【００５１】
これに対し検出系、操作系として用いられるものは以下となる。
＜検出系＞
・ファン１６の回転検出装置
・排気ファン１９の回転検出装置
・ドアスイッチ
・メンテナンススイッチ
・ファン１６の直下の流速検出装置
・接続路４の流速方向検出装置（流速センサ２０）
＜操作系＞
・ファン１６の駆動制御装置
・排気ファン１９の駆動制御装置
・接続路４の遮断機構
【００５２】
また、汚染伝播対策とは別に、初期立ち上げ時に清浄度管理を構築していくためにも図９のようにモニタシステム２５の画面上に差圧、流速、方向が表示され、各々のモジュール３に充分なダウンフロー状態が構築できている事と要求される清浄度、工程での汚染発生に応じた接続路４内の流れの方向を流速確認する事が可能で、この情報に基づき各ファン１６の運動を決定する事ができる。またモニタシステム２５のコンピュータにその制御状態を複数タイプ登録しておき運転状況に応じて切り替える事も可能となる。このようにした場合、生産量に応じて清浄度管理の強弱を制御したり夜間の停止時の電力削減にも役立つ。
【００５３】
以上説明したように、本実施形態の汚染伝播防止システム１では以下のことが可能である。
・汚染検出、予知を行い汚染の伝播を遮断することで汚染が製造システム全体に広がることを抑える事ができる。
・汚染検出は接続路４の流速ベクトルの検出と併用する事で有効な汚染モジュール３の特定が行える。
・ファン１６の停止、扉１８の開状態の検出も接続路４の流速ベクトル検出と併用することで検出、予知の確度をあげる事が可能で状況に応じた適切な処置を講じる事ができる。
・接続路４の流速ベクトルの検出は製造システム（中でも特に自走式ワーク搬送パレットを利用したような小型のシステム）の大きな問題であるのに対し、汚染伝播以外にも清浄度構築のためのファン１６の速度の設定などにも有用な情報が提供できる。
・汚染の伝播の防止に対しては機械的方法と空気流制御が有効である。
・空気流制御による伝播の防止は緊急の伝播遮断に対して低コストでできる。こ場合、特にハードウェアの追加なしに実現できることからその分低コスト化に有利である。また、機械的方法では、機構そのものの発塵対策が必要であるが、空気流制御の場合は、気流変化によるパーティクルの巻き上げを考慮するのみで良い。
・汚染されたモジュール３を再度清浄化する際にはファン１６の動作を急激に立ち上げず徐々に立ち上げて行く事が伝播を発生させない上で重要である。
・汚染伝播管理、清浄度構築のためにはモニタシステム２５等のネットワークにより各検出系、ファン制御などの遮断機構がコンピュータに接続されトータル管理される事が重要である。
【００５４】
なお、上述の実施形態は本発明の好適な実施の一例ではあるがこれに限定されるものではなく本発明の要旨を逸脱しない範囲において種々変形実施可能である。例えば本実施形態における汚染発生予測手段は、接続路内の空気の流速と流れ方向の情報に基づいて汚染の発生を予測するものであったが、これ以外の要因、例えば製造システムの清浄領域Ｃと外気とを仕切る扉が開いたことの検出、あるいはメンテナンスを行う事を宣言する意味で作業者が明示的に釦を押すなどの操作することの検出によって汚染発生を予測することもできる。
【００５５】
【発明の効果】
以上の説明より明らかなように、請求項１記載の汚染伝播防止システムによると、内部に清浄領域を有する複数の局所清浄装置が接続されている製造システムにおいて、何らかの原因で汚染が発生した場合に汚染が周辺の局所清浄装置に伝播されることを防止し、製造への影響を最小限に食い止めることが可能となる。
【００５６】
請求項２記載の汚染伝播防止システムによると、例えば空気流速や流れ方向が急激に変化したような場合、いずれかの局所清浄装置で扉が開いて外気と通じたなどして汚染が発生したことを予測することができる。あるいは、清浄空気生成手段の停止、清浄領域と外気との差圧の変化などによっても汚染発生を予測できる。
【００５７】
請求項３記載の汚染伝播防止システムによると、例えば空気流速や流れ方向が急激に変化したような場合にいずれかの局所清浄装置で発生した汚染が伝播することを予測することができる。したがって、この予測に基づいて汚染伝播を早期に防止することができる。
【００５８】
請求項４記載の汚染伝播防止システムによると、清浄空気発生手段により生ずる清浄空気の流速や流量を調節することにより、汚染されていない局所清浄装置に汚染が伝播するのを防止できる。
【００５９】
請求項５記載の汚染伝播防止システムによると、不良品の製造を回避し、汚染粒子が下流工程の治工具類に転写されてしまう事を避けることができる。
【００６０】
請求項６記載の汚染伝播防止システムによると、伝播の可能性が無いと判断されたものに関しては汚染可能性が無い範囲までは通常の製造作業が続行されるようにして可能な範囲内で製造効率を維持することが可能となる。
【００６１】
請求項７記載の汚染伝播防止システムによると、汚染が発生した局所清浄装置あるいは接続路の清浄度を回復させた後に製造を再開することができる。
【００６２】
さらに請求項８記載の汚染伝播防止システムによると、急激なダウンフローが生じ、汚染が解消されないうちに汚染が他の局所清浄装置に流れ込んでしまうのを防止することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示す汚染伝播防止システムの全体図である。
【図２】パーティクルカウンタの構成例を示す概略図である。
【図３】カバーが外され剥き出しにされた固体撮像素子の斜視図である。
【図４】タバコの煙を清浄領域Ｃ内にストローで導入した調査の様子を示す図である。
【図５】「破壊」のケースを想定して実施したテストの様子を示す図である。
【図６】前面扉を完全開放した調査の様子を示す図である。
【図７】清浄領域内で発生した汚染と空気の流れとを示す図である。
【図８】温度センサの構造を示す（Ａ）平面図と（Ｂ）側面図（直流電源との接続を含む）である。
【図９】モニタシステムが接続された汚染伝播防止システムを示す図である。
【図１０】汚染伝播に対して直角方向に空気流を発生させる制御手法を示す汚染伝播防止システムの図である。
【図１１】汚染発生時における局所清浄装置の遮断状態を示す図である。
【図１２】汚染が発生した局所清浄装置において急激なダウンフローを生じさせた場合の様子を示す図である。
【図１３】汚染が発生した局所清浄装置において徐々にダウンフローを生じさせた場合の様子を示す図である。
【図１４】接続された複数の局所清浄装置の内の１つで汚染が発生した様子の一例を示す図である。
【図１５】接続された局所清浄装置の内の１つの内部の清浄領域が外気と接続されて汚染が発生した様子の一例を示す図である。
【符号の説明】
１　汚染伝播防止システム
２　ワーク
３　モジュール（局所清浄装置）
４　接続路
１６　ファン（清浄空気発生手段）
１７　フィルタ（清浄空気発生手段）
１９　排気ファン（排気手段）
Ｃ　清浄領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pollution propagation prevention system. More specifically, according to the present invention, a plurality of local cleaning devices that perform predetermined manufacturing processes such as assembly and processing of a work are connected by a tubular connection path to form a cleaning region, thereby realizing a series of cleaning manufacturing processes. The present invention relates to an improvement of a contamination propagation prevention system in a manufacturing system.
[0002]
[Prior art]
A manufacturing system that connects a plurality of modularized local cleaning devices that perform predetermined manufacturing processes such as assembly and processing of a workpiece by a tubular connection path to form a cleaning region C and realize a series of cleaning manufacturing processes is used. (See FIG. 14). In such a manufacturing system, the local manufacturing apparatus (module) 101 is connected to be connected to another module 101 by a connection path 102, and is configured to sequentially transport the work in the clean area C and perform processing or the like. . The clean area C is kept clean, for example, by a structure in which a clean air flow that has passed through the filter 103 is caused to flow down from the fan 104 above the module and from the small hole of the partition 105 below the clean area C to the lower side.
[0003]
[Problems to be solved by the invention]
However, such a manufacturing system has an excellent feature that it can be miniaturized and can realize a high degree of design freedom, but has a structure in which the modules 101 are successively connected and the volume of the clean area is small. Therefore, when contamination occurs for some reason, there is a problem that this contamination is propagated not only to one module 101 but also to the connected modules 101 (see FIG. 14). Such a problem is particularly serious in a miniaturized so-called desktop manufacturing system, because the spacing between the devices is close, and the problem of the propagation of contamination is more serious.
[0004]
Therefore, an object of the present invention is to provide a pollution propagation prevention system capable of efficiently and reliably preventing the propagation of contamination particularly when unexpected contamination occurs in a clean area of a small-sized manufacturing system. I do.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, the present inventors have conducted various studies on various conventional means. For example, in a manufacturing system as shown in FIG. 14 and FIG.
A. When contamination occurs in one of the connected modules (FIG. 14)
B. When the internal clean area of one of the connected modules is connected to the outside air and the pressure and flow of the clean air are disturbed (FIG. 15).
There is. Also, as yet another case
C. When the generation of clean air flow stops for some reason, such as when the fan stops.
(Case A is called "contamination", case B is called "destruction", and case C is called "stop").
[0006]
The best way to deal with such "pollution", "destruction" and "stop" is considered to be slightly different, but the following measures must be taken as basic measures.
[0007]
(1) Pollution, destruction, stop detection, or prediction
(2) Prevention of contamination transmission
(3) Marking of potentially contaminated work
(4) Protection of non-contaminated work
5) Repair of pollution, destruction and suspension
(6) Resume normal production
[0008]
The inventor of the present application has studied variously to realize such various countermeasures, and has come to know a system suitable for preventing propagation of the contamination when the contamination occurs in the manufacturing system. The present invention is based on such knowledge, and the invention according to claim 1 forms a clean area by connecting a plurality of local cleaning devices that perform predetermined manufacturing processes such as assembling and processing of a workpiece by a tubular connection path. In a contamination propagation prevention system in a manufacturing system that realizes a series of clean manufacturing processes, a local cleaning device or a connection path, a contamination occurrence detecting means for detecting contamination occurring in a clean area inside the system or a contamination for predicting the occurrence of contamination. At least one of occurrence prediction means, contamination propagation prediction means for predicting propagation of generated contamination to other local cleaning devices, and contamination propagation preventing means for preventing propagation of generated contamination to other local cleaning devices Are provided.
[0009]
According to this contamination propagation prevention system, when contamination occurs in a clean area, the contamination can be detected or the occurrence of contamination can be predicted, and the generated contamination can be transmitted to other local cleaning devices. Can be predicted and prevented. Contamination detection can be performed, for example, by monitoring air in the manufacturing system using a particle counter or the like, or by counting particles that have settled on the image sensor.
[0010]
The invention according to claim 2 is characterized in that the pollution occurrence predicting means is means for predicting the occurrence of pollution based on information on the flow velocity and the flow direction of the air in the connection path. For example, when the air velocity or the flow direction changes suddenly, it is possible to predict that contamination has occurred due to, for example, the door being opened by any of the local cleaning devices and communicating with the outside air. Alternatively, the occurrence of contamination can also be predicted by stopping the clean air generation means, or changing the pressure difference between the clean area and the outside air.
[0011]
The invention according to claim 3 is characterized in that the pollution propagation prediction means is means for predicting the propagation of pollution based on information on the flow velocity and the flow direction of the air in the connection path. For example, when the air flow velocity or the flow direction changes suddenly, it is possible to predict that the contamination generated in any of the local cleaning devices propagates.
[0012]
In the invention according to claim 4, the contamination propagation preventing means is configured to perform the local cleaning device based on the information on the flow velocity and the flow direction of the air in the local cleaning device in which the contamination is detected or predicted and the connection path connected to the local cleaning device. It is a means for controlling the clean air generating means provided in the local cleaning device connected to the connection path. By adjusting the flow rate and flow rate of the clean air generated by the clean air generating means, it is possible to prevent the contamination from propagating to a local cleaning device that is not contaminated.
[0013]
Further, in the contamination propagation prevention system according to the first aspect, as described in the fifth aspect, the work existing in the local cleaning device where the contamination is detected or predicted and the workpiece is sequentially connected upstream or downstream from the local cleaning device. It is preferable to perform defective discharge or re-cleaning of the work existing in the predetermined number of local cleaning devices or the connection paths. As a result, production of defective products can be avoided, and contaminant particles can be prevented from being transferred to jigs and tools in a downstream process.
[0014]
In the pollution propagation preventing system according to the first aspect, as in the sixth aspect, a process further downstream than a predetermined number of local cleaning devices sequentially connected downstream from the local cleaning device in which contamination is detected or predicted. It is preferable that the production of the work existing in the local cleaning apparatus is continued, and the production of the local cleaning apparatus in which the contamination is detected or predicted and the production in the predetermined local cleaning apparatus sequentially connected upstream from the local cleaning apparatus be stopped. With respect to those determined to have no possibility of propagation, normal manufacturing operations can be continued to the extent that there is no possibility of contamination, so that manufacturing efficiency can be maintained within the possible range.
[0015]
According to a seventh aspect of the present invention, there is provided a contamination propagation prevention system including a cleanliness recovery unit for recovering the cleanliness of a local cleaning device or a connection path that has been detected or predicted. According to this system, manufacturing can be resumed after the cleanliness of the local cleaning device or the connection path in which the contamination has occurred is restored.
[0016]
According to the seventh aspect of the present invention, as described in the eighth aspect, the cleanliness recovery means includes a clean air generating means and an exhaust means for evacuating the local cleaning device. Based on information on the local cleaning device in which contamination has been detected or predicted and the flow velocity and flow direction of air in the connection channel connected to the local cleaning device, cleaning provided in the local cleaning device connected to the connection channel. This is performed by reducing the flow rate of the clean air from the air generation means, and the restoration of cleanliness is required by using the reduced flow rate of the clean air from the clean air generation means to ensure the cleanness of the clean area. It is preferable to perform this by gradually increasing the flow rate to an appropriate level. It is possible to prevent a sudden downflow from occurring and the contamination from flowing into another local cleaning device before the contamination is resolved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.
[0018]
1 to 13 show an embodiment of the present invention. The contamination propagation prevention system 1 of the present invention connects a plurality of local cleaning devices 3 (hereinafter, also referred to as “modules 3”) that perform predetermined manufacturing processes such as assembly and processing of a work 2 by connecting through a tubular connection path 4. This is applied as a system for preventing the propagation of contamination in the manufacturing system 1 that forms the region C and realizes a series of clean manufacturing processes. In the contamination propagation prevention system 1 of the present embodiment, the local cleaning device 3 or the connection path 4 has a contamination occurrence detecting means for detecting contamination occurring in a clean area C in the system or a pollution occurrence predicting means for predicting the occurrence of contamination. And a contamination propagation prediction unit for predicting the propagation of the generated contamination to another local cleaning device 3, and a contamination propagation preventing unit for preventing the generated contamination from transmitting to the other local cleaning device 3. Is provided. In FIG. 1 and the like, hatching in the cross section of the local cleaning device 3 and the like is omitted.
[0019]
Hereinafter, a form in which the contamination propagation prevention system 1 according to the present invention is applied to a manufacturing system that automatically conveys a work 2 using a self-propelled work conveyance pallet that has four wheels and self-propelled along a rail, for example, will be described. The module 3 is provided with a clean air generating means including a fan 16 and a filter 17. In the clean area C in the module 3, clean air that has passed through a filter 17 such as HEPA (High Efficiency Particulate Air Filter) is blown out by a fan 16. The clean air flows downward through a partition wall (for example, made of punch metal) 9 provided with a plurality of small holes. The self-propelled work transport pallet is detachably provided with, for example, a thin work mounting portion for mounting the work 2 thereon. Both the self-propelled work transport pallet and the work placement unit are provided with a rewritable storage function, so that information on the work 2 and the like can be updated at any time. Accordingly, the contamination propagation prevention system 1 of the present embodiment stores the information when it is determined that there is a contaminated work 2, for example, and informs itself of the possibility of contamination based on the stored contents. It is possible to store it on a work-type work transfer pallet or a work mounting part and transfer it to a point where it can be discharged.
[0020]
In the following, regarding various examinations and embodiments related to such a contamination propagation prevention system 1, “detection and prediction”, “marking of contaminated work”, “identification of contaminated work”, “rescue of non-contaminated work”, “flow rate” Each of the items "vector detection", "prevention of contamination propagation", and "recovery" will be described.
[0021]
1. Detection, prediction
In a clean area C such as a clean room in a conventional manufacturing system, various measuring means for confirming cleanliness have been established, and can be used as a contamination occurrence detecting means. For example, means for directly measuring contaminant particles (particles) using a particle counter 10 as shown in FIG. 2 uses light from a photodiode 12 and light from a laser device 13 to sample air sucked by a suction machine 11. Irradiation with laser light is performed to detect scattered light by particles to detect the degree of contamination. Further, as shown in FIG. 3, a sedimentation test is performed in which the luminance change of each pixel of the solid-state imaging device 14 whose cover is removed and exposed is measured, and the sedimentation of particles is detected based on the number of luminance reduction pixels per unit time. . In addition to the above-described direct measurement means, indirect means such as measurement of the differential pressure between the clean area C and the non-clean area, measurement of the flow velocity of the clean air flow, and measurement of the flow velocity vector are performed. These indirect measurements do not measure the pollution itself, but because these are one of the major factors of the pollution, the pollution is predicted in advance by detecting an abnormality in the control state of the clean air. Can do things. These means and methods can be used as pollution occurrence prediction means, that is, means for predicting the occurrence of pollution based on information on the flow velocity and flow direction of the air in the connection path 4. Further, it can be used as pollution propagation prediction means, that is, means for predicting the propagation of pollution based on information on the flow velocity and the flow direction of the air in the connection path 4. The opening of the door 18 in the local clean area C in the module 3, the execution of the specific operation of the specific process, and the like are factors that cause the occurrence of contamination without fail. Therefore, door switches and maintenance switches are also important for detecting and predicting contamination.
[0022]
In the present embodiment, various detection methods are performed for each of the cases of “contamination”, “destruction”, and “stop” (see Table 1 below). Table 1 shows the factors of each case of "contamination", "destruction", and "stop", and the urgency of the case (approximate indication of how urgent it is to deal with the case). Are also shown.
[Table 1]

[0023]
2. Marking contaminated workpieces
Next, a description will be given of how to mark the contaminated work 2 and prevent the propagation of the contaminated work 2 when the contaminated work 2 occurs inside each module 3 of the manufacturing system (see FIG. 1). In the manufacturing system shown in FIG. 1, the work 2 is transported from the left side (upstream side) to the right side (downstream side) in the figure, and the case where contamination occurs in the fifth module 3 from the left side is shown. The elliptical area indicated by the symbol A1 indicates an area that is contaminated by the time the treatment is completed, and the white elliptical area indicated by the code A2 indicates an area where the contamination is likely to be propagated by the time the treatment is completed.
[0024]
If it is determined from the above detection and prediction that there is a possibility of contamination of the work 2, not only does it make no sense to manufacture a defective product, but also a more important problem is that contaminated particles are transferred to jigs and tools in the downstream process. In order to avoid such a situation, it is desirable to mark the work 2 which may be contaminated, and transport and discharge the work 2 to a place where discharge is possible. For example, in the case of the present embodiment, since the self-propelled work transport pallet and the work placement unit are provided with a storage function, the fact that there is a possibility of contamination is stored in the self-propelled work transport pallet or the work placement unit. The stored state is read out in the process of passing to a point where the workpiece 2 can be discharged, and a control is performed so that the workpiece 2 is not touched. In addition, discharge of the work 2 existing in the module 3 in which the contamination is detected or predicted and the work 2 existing in the predetermined number of modules 3 or the connection path 4 sequentially connected upstream or downstream from the module 3 I do. In addition, at a point where the work 2 can be discharged, it is preferable that the work 2 is discharged and discarded, while the work mounting portion is cleaned and used again. At this point in time, the stored potential contamination memory is rewritten to be non-contaminated. Instead of discharging the work 2, it is also possible to wash and use the work 2 in the same manner as the work mounting portion.
[0025]
3. Identification of contaminated work
The module 3 on which contamination is predicted and detected and the work 2 near the module 3 are marked as described above to be defective, but the assembly of the work 2 on the downstream side and within a range where the propagation of the contamination is prevented is continued. Is possible. On the upstream side, production can be continued without waste by temporarily waiting, that is, waiting until normal production processing is resumed. In the case of “stop” due to an abnormality of the fan 16, the time from when it is predicted to when it is actually contaminated is long, and the work 2 immediately after detection is not contaminated. In this case, efficient processing can be maintained by performing processing such as stopping the transfer of the work 2 to the process after a certain period of time. The extent to which contamination is propagated is determined to some extent by the structure for maintaining cleanliness in the manufacturing system, the propagation prevention method, the detection prediction method, and their time.
[0026]
Here, as a case of “contamination”, a result of investigation on contamination when cigarette smoke is introduced into the clean area C with the straw 15 is shown (see FIG. 4). Here, breathing for 5 to 6 seconds after smoking is blown around the stop position of the self-propelled work transfer pallet. In this case, about 2,300 contaminant particles having a diameter of about 0.3 μm were detected. Further, 30 seconds later, the number of particles in the module 3 was reduced to 30 and about 200 particles were detected in the adjacent module 3. As a result, it was confirmed that, although most of the tobacco smoke was exhausted to below the partition wall 9 having the small holes by the downflow and the density was reduced to about 1/10, there was propagation to the adjacent clean area C. . At this time, it was also confirmed that the correlation with the rail shape was actually large, and that the propagation amount was drastically reduced when the lower surface of the rail had a grating shape. In addition, propagation due to movement of the self-propelled work transfer pallet was also observed. Since the self-propelled work transfer pallet traveled while entraining smoke particles, a large amount of particles was also observed on the downstream side.
[0027]
Further, test results performed on the assumption of a “destruction” case will be described (see FIG. 5). This test was performed by evaluating the state where the door 18 on one side of the connected module 3 was opened. Pollution status largely depends on the size and height of the open area. Here, as shown in FIG. 5, an opening of about 50 × 80 [mm] was provided on the side wall of the module 3 with respect to a clean area of 170 × 230 × 200 [mm]. In this case, no deterioration in cleanliness occurred. Further, as shown in FIG. 6, when the opening area is widened by completely opening the front door 18, particles of 10,000 or more are observed on the open side and about 20 particles are observed on the adjacent module 3, and are hardly affected. I understood that.
[0028]
The following conclusions were also obtained through these experiments. That is,
(1) The correlation between the differential pressure with the outside air and the cleanliness if the sealing in the clean area C from the upper filter 17 to the transfer surface of the workpiece 2 is complete (or close to this). Relationship is low.
(2) The flow rate of the clean air and the direction of its vector are very important, and it is important that the flow in the negative direction is maintained with respect to the polluted environment.
(3) The speed of the contamination extension itself is very slow, and the magnitude of the flow velocity vector does not need to be fast.
[0029]
Note that the “negative direction” here refers to the direction of flowing from the clean environment to the contaminated environment, and the positive direction conversely refers to the direction of flowing from the contaminated environment to the clean environment (see FIG. 7). In addition, the conclusion of (3) is that the fan 16 on the open side is stopped with the front door 18 fully opened, and then the fan 16 of the module 3 is stopped next to the next, and after standing for 30 seconds or more, the particle count is started. It was determined based on the fact that began.
[0030]
As a conclusion to this point, assuming that the problem of contamination of the work 2 with respect to the observation can be dealt with within 10 seconds, the following contamination spread is assumed for each detection and prediction. You can do it.
[0031]
(1) In the case of detecting contamination by a particle counter
It must be determined that the detected work 2 in the module 3 is contaminated. In the experiment, it can be determined that there is no possibility of contamination on both sides, but propagation can be almost certainly determined from the relationship with the flow velocity vector described later.
[0032]
(2) Prediction of contamination due to reduced differential pressure
Contamination does not occur in a short time even if a decrease in the differential pressure is confirmed. Therefore, if the time of the process in the module 3 is, for example, 30 seconds or less, it can be considered as a good product. However, the decrease in the differential pressure is likely to occur almost simultaneously in the connected modules 3, and it is difficult and time-consuming to identify the module 3 that caused the case where only the differential pressure decrease was detected. It is difficult to recover within 30 seconds, and it is not desirable to use only the differential pressure detection as a detection prediction method.
[0033]
(3) Prediction of contamination by flow velocity and direction
If the flow velocity and its direction can be roughly measured, the extent of contamination can be estimated fairly accurately. In the case of a manufacturing system using a self-propelled work transfer pallet as in the present embodiment, the path through which contamination propagates is only the connection path 4, and the diffusion speed of the contaminated particles is very slow relative to the wind speed. This is because it is considered to be. That is, when the movement of the self-propelled work transfer pallet is not considered, it is considered that the contamination moves only by using the air passing through the connection path 4 as a medium, and detecting the movement of the air in the connection path 4 is for maintaining the cleanliness. It is very important for them. If the flow velocity vector is detected in the discharge direction for the module 3 where the contamination has been detected, it may be determined that the contamination has propagated.
[0034]
4. Relief of non-contaminated work
Although the treatment of the work 2 which may be contaminated is related to a method of blocking propagation described later, basically, all the work 2 which may be contaminated is discharged as a defective product and discarded or washed again. And re-input. On the other hand, the production of the work 2 existing in a process further downstream than the predetermined number of modules 3 sequentially connected downstream from the module 3 in which contamination is detected or predicted continues, and the modules 3 and 3 in which contamination is detected or predicted. The manufacturing of the work 2 in a predetermined module 3 sequentially connected to the upstream side from the module 3 is interrupted. In other words, the normal production operation is continued to the extent that there is no possibility of contamination for those determined to have no possibility of propagation. Then, in a step upstream of the step (a step having a possibility of contamination: including a plurality of steps), production up to the step is continued, and production and transport are interrupted in a step immediately before the step. In the downstream, the charging from the process is not performed, and the work is automatically stopped in a state of waiting for the charging in order, and the process waits after the work 2 is sent out. By such control, it is possible to control so that no waste product is output to the work 2 having no possibility of contamination.
[0035]
In addition, when the rails are combined in a complicated manner, the transfer of the work 2 by the self-propelled work transfer pallet cannot be considered simply upstream or downstream. In some cases, assembling is performed, so that the situation becomes more complicated. However, it is assumed that the order is not the order of the apparatus but upstream and downstream along the process diagram.
[0036]
5. Flow velocity vector detection
As described above, it can be said that the detection of the flow velocity is an effective means for estimating the contamination propagation. In the manufacturing system to which the module 3 in which the clean region C is locally formed as in the present embodiment is connected, the detection of the decrease in the differential pressure is not immediately linked to the contamination in a short time as described above. Further, even if it is possible to detect that the door 18 has been opened, it is difficult to specify which module 3 the door 18 is. From this fact, the differential pressure detection often used in the conventional clean room is not suitable, and it can be said that the detection of the flow velocity vector is an effective means. By detecting the flow velocity of the connection path 4, it is possible to grasp not only the estimation of the contamination propagation but also other important problems related to cleanliness management.
[0037]
(1) When all negative vectors are detected in connection path 4
When the flow velocity vector of the connection path 4 connected to one module 3 greatly changes in the negative direction, it can be determined that the connection is directly made with the outside air. Here, the “direct connection” includes, for example, opening of the maintenance door 18. When such a determination is made, the possibility that contamination has occurred is very high, and the entire clean region C of the module 3 can be confirmed for a device such as a particle monitor that can only perform local measurement to some extent. A similar situation occurs when the fan 16 is stopped. However, the speed of the change of the flow velocity vector is slower than the opening of the door 18. Since detection of the stop of the fan 16 does not require much cost, it is better to have a separate detector. However, detection can be performed by vector fluctuation detection.
[0038]
{Circle around (2)} When all forward vectors are detected in connection path 4
It is possible to monitor that the propagation blocking operation described later is performed reliably.
[0039]
(3) When a vector in the negative direction and a vector in the positive direction are detected in the connection path 4
Contamination may be transmitted from the connection 4 in the negative direction. Therefore, it is necessary to confirm the determination status of the module 3 connected to the connection path 4 and determine the contamination. In this case, the propagation of the contamination is considered to be proportional to the magnitude of the velocity vector.
[0040]
Being able to monitor the flow velocity vector of the connection path 4 separately from such contamination monitoring is effective in cleanliness design, that is, individual module management in the module 3 where there is a lot of pollution or there is a concern about the contamination or in a process that dislikes the pollution. . In the manufacturing system of this embodiment, it is easy to assign a unit of cleanliness management to the module 3 (the differential pressure and the flow rate can be managed independently because the module 16 has the fan 16 and the lower exhaust fan 19). . However, even if the air management of the individual modules 3 is performed, in the state where the modules are connected by the connection path 4, the differential pressures are all constant and the direction of the contaminated particles cannot be grasped. As described above, since the contaminant particles travel by moving through the connection path 4, the contamination propagation can be set in advance as desired.
[0041]
As a sensor for detecting the flow velocity vector in the connection path 4, for example, a temperature sensor 20 including a resistance heating element 21, a thermistor 22, a heat insulating substrate 23, a DC power supply 24, and the like as shown in FIG. 8 can be used.
[0042]
6. Prevent contamination transmission
In the present embodiment, a contamination propagation preventing means for preventing the contamination from being propagated to the clean module 3 when the contamination occurs is provided. The pollution propagation preventing means includes, for example, the module 3 connected to the connection path 4 based on information on the module 3 in which the contamination is detected or predicted and the flow velocity and the flow direction of the air in the connection path 4 connected to the module 3. However, the present invention is not limited to this, and can be realized by, for example, the following methods a) to d).
(1) Mechanical disconnection of connection path 4
a) Installation of mechanical shutter
In mechanical shut-off, since it has a mechanically movable part, it may itself be a source of contamination. Therefore, there is still a problem in preventing immediate transmission, but this is an effective method when shutting off for a long time.
[0043]
b) Blocking by inflating balloon-like objects
The blocking method of inflating things on the balloon can prevent the occurrence of contamination by moving parts, but actually requires a pneumatic source to inflate.
[0044]
(2) Shut off by controlling air flow
c) Control to generate a flow velocity vector toward the upstream of pollution propagation
It is clear from the above embodiment that the control of the flow velocity vector is most effective for immediate shutoff. In this case, the fan 16 of the module 3 which is presumed to be a contamination source is simply stopped, or the rotation speed of the exhaust fan 19 as the exhaust means is increased (both may be performed). In the case of urgent manual operation, it is possible to simply open the contamination source door 18 by a certain amount. As shown in FIG. 9, when a monitor system 25 including a computer connected to the fan 16, the exhaust fan 19, and the flow velocity sensor 20 of each module 3 is used, how long after the occurrence of contamination, the shut-off is required. It is also possible to acquire and log (register) information such as whether or not a flow velocity vector has been obtained.
[0045]
d) Control to generate airflow in a direction perpendicular to the propagation of contamination (see FIG. 10)
The method of generating a right-angled air flow in the connection path 4 in d) may be a method of controlling the air flow at the time of contamination detection and prediction, but unlike c), there is no problem even if this air is flowed during air control. And a state where propagation of contamination is always interrupted can be realized. A state in which the propagation of contamination is always interrupted can be realized by the airflow in the perpendicular direction. The fan 26 and the filter 27 are provided when the pressure in the connection path 4 cannot be maintained at a positive pressure. In order to block the flow of air between the two modules 3, an exhaust fan 28 is provided in the connection path 4.
[0046]
7. recovery
Further, the contamination propagation prevention system 1 has a cleanliness recovery unit for recovering the cleanliness of the module 3 or the connection path 4 where the contamination is detected or predicted. The cleanliness recovery means includes, for example, clean air generating means (fan 16 and filter 17) and exhaust means (exhaust fan 19). This is performed by reducing the flow rate of the clean air from the clean air generating means provided in the module 3 connected to the connection path 4 based on the information on the flow velocity and the flow direction of the air in the connection path 4 to be connected. At the same time, the cleanliness recovery is performed by gradually increasing the flow rate of the reduced clean air from the clean air generating means to a flow rate necessary for ensuring the cleanliness of the clean area C.
[0047]
After the prediction and detection of the contamination, the prediction of the propagation, and the blocking of the propagation are performed, it is desirable to specify the pollution source and take a countermeasure. After this is completed, the contaminated module 3 is cleaned, and a means of releasing the transmission cutoff is taken. After the cause is removed, the internal cleaning area C is closed and cleaned after wiping and the like are performed. The cleaning in the single module 3 is performed 20 to 30 seconds after the operation of the fan 16 is started due to the small internal cleaning area C. Further, as a measure for blocking the propagation of contamination, when the propagation to the connected module 3 is interrupted by the inflow from the connection path 4 due to the stoppage of the fan 16 of the contamination module 3, the cleanliness recovery of the contaminated module 3 is performed. As a result, the dust propagates to the adjacent module 3, that is, the module 3 without contamination, by the operation of the fan 16.
[0048]
That is, in the shut-off state shown in FIG. 11, the air flowing from the non-contaminated module 3 to the contaminated module 3 can prevent the propagation of contamination. Such a rapid downflow may occur, and the contamination may flow into the non-contamination module 3 before the contamination is resolved. With respect to such a problem, by performing the following two-stage control on the fan 16, the contaminated module 3 can be recovered without causing the contaminated module 3 to propagate the contaminated module (FIG. 13). reference).
{Circle around (1)} The rotation speed of the fan 16 is gradually increased to a set value over about 25 seconds.
(2) Wait 10 seconds at the set value.
[0049]
Almost all of the contamination has already been recovered at the stage of (1), but it is necessary to wait at (2) until the conditions for cleaning are stabilized (the air flow is in a normal state). If the time of (1) is too short, the propagation of contamination to the surroundings will occur, but the longer time will only require recovery time. If the productivity of this case does not matter much, the time is as short as possible. And start slowly.
[0050]
8. Conclusion
The control described so far is summarized as follows.
Detection of contamination occurrence
↓
Propagation estimation
↓
Propagation cutoff
↓
Countermeasure processing
↓
recovery
[0051]
On the other hand, the following are used as a detection system and an operation system.
<Detection system>
.Detection device for rotation of fan 16
.A rotation detecting device of the exhaust fan 19
・ Door switch
・ Maintenance switch
・ Flow velocity detector just below fan 16
· Flow direction detecting device for flow path 4 (flow rate sensor 20)
<Operation system>
.Drive control device for fan 16
.Drive control device for exhaust fan 19
.Interruption mechanism for connection path 4
[0052]
In addition to countermeasures against contamination propagation, in order to establish cleanliness control at the time of initial startup, the differential pressure, flow velocity, and direction are displayed on the screen of the monitor system 25 as shown in FIG. It is possible to check the flow rate in the connection path 4 in accordance with the required cleanliness and required cleanliness, and the occurrence of contamination in the process. Sixteen exercises can be determined. It is also possible to register a plurality of types of control states in the computer of the monitor system 25 and switch them according to the operating conditions. In this case, it is also useful to control the degree of cleanliness management according to the production amount and to reduce the power consumption during a night stop.
[0053]
As described above, the contamination propagation prevention system 1 of the present embodiment can perform the following.
・ Contamination can be prevented from spreading to the entire manufacturing system by detecting and predicting contamination and blocking the propagation of the contamination.
The effective detection of the contamination module 3 can be performed by using the contamination detection together with the detection of the flow velocity vector of the connection path 4.
The detection of the stop of the fan 16 and the detection of the open state of the door 18 can be used together with the detection of the flow velocity vector of the connection path 4 to improve the accuracy of detection and prediction, and to take appropriate measures according to the situation.
-The detection of the flow velocity vector of the connection path 4 is a major problem in a manufacturing system (especially a small system using a self-propelled work transfer pallet), but it is not only for the propagation of contamination but also for the construction of cleanliness. Useful information can also be provided for setting the speed of the fan 16 and the like.
・ Mechanical methods and air flow control are effective in preventing the propagation of contamination.
-Propagation prevention by air flow control can be performed at a low cost for emergency transmission interruption. In this case, since it can be realized without any additional hardware, it is advantageous in reducing the cost. Further, in the mechanical method, it is necessary to take measures against dust generation of the mechanism itself. However, in the case of airflow control, it is only necessary to consider the winding of particles due to a change in airflow.
When cleaning the contaminated module 3 again, it is important to gradually start the operation of the fan 16 without suddenly starting the operation, in order to prevent propagation.
It is important for the control of contamination propagation and the construction of cleanliness that a network such as the monitor system 25 and the like, each detection system and a shut-off mechanism such as a fan control be connected to a computer for total management.
[0054]
The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, the contamination occurrence prediction means in the present embodiment predicts the occurrence of contamination based on information on the flow velocity and the flow direction of the air in the connection path, but other factors such as the clean area C of the manufacturing system. It is also possible to predict the occurrence of contamination by detecting that the door that separates the air from the outside has been opened, or by detecting that the operator explicitly presses a button or the like in the sense that maintenance is to be performed.
[0055]
【The invention's effect】
As is clear from the above description, according to the contamination propagation prevention system of the first aspect, in a manufacturing system in which a plurality of local cleaning devices having a cleaning area inside are connected, if contamination occurs for any reason. It is possible to prevent the contamination from being transmitted to the local cleaning device in the vicinity, and to minimize the influence on the production.
[0056]
According to the pollution propagation prevention system according to the second aspect, for example, when the air flow velocity or the flow direction changes suddenly, the contamination has occurred because the door was opened by any one of the local cleaning devices to communicate with the outside air. Can be predicted. Alternatively, the occurrence of contamination can also be predicted by stopping the clean air generation means, or changing the pressure difference between the clean area and the outside air.
[0057]
According to the contamination propagation prevention system of the third aspect, it is possible to predict that the contamination generated in any one of the local cleaning devices is propagated when, for example, the air flow velocity or the flow direction changes suddenly. Therefore, contamination propagation can be prevented at an early stage based on this prediction.
[0058]
According to the pollution propagation prevention system of the fourth aspect, by controlling the flow rate and the flow rate of the clean air generated by the clean air generating means, it is possible to prevent the propagation of the pollution to the unclean local cleaning device.
[0059]
According to the contamination propagation prevention system of the fifth aspect, it is possible to avoid the production of defective products and the transfer of contaminated particles to jigs and tools in the downstream process.
[0060]
According to the contamination propagation prevention system according to the sixth aspect, if it is determined that there is no possibility of propagation, normal production work is continued to the extent that there is no possibility of contamination, and production is performed within a possible range. It is possible to maintain efficiency.
[0061]
According to the contamination propagation prevention system according to the seventh aspect, the production can be resumed after the cleanliness of the local cleaning device or the connection path where the contamination has occurred is restored.
[0062]
Further, according to the contamination propagation prevention system of the present invention, it is possible to prevent a sudden downflow from occurring and the contamination from flowing into another local cleaning device before the contamination is eliminated.
[Brief description of the drawings]
FIG. 1 is an overall view of a pollution propagation preventing system according to an embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a configuration example of a particle counter.
FIG. 3 is a perspective view of the solid-state imaging device with a cover removed and exposed.
FIG. 4 is a diagram showing a state of an investigation in which tobacco smoke is introduced into a clean area C with a straw.
FIG. 5 is a diagram showing a state of a test performed assuming a “destruction” case.
FIG. 6 is a diagram showing a state of an investigation in which a front door is completely opened.
FIG. 7 is a diagram showing contamination and air flow generated in a clean area.
FIGS. 8A and 8B are a plan view and a side view (including a connection to a DC power supply) showing the structure of the temperature sensor.
FIG. 9 is a diagram showing a pollution propagation prevention system to which a monitor system is connected.
FIG. 10 is a diagram of a pollution propagation prevention system showing a control method for generating an airflow in a direction perpendicular to the pollution propagation.
FIG. 11 is a diagram illustrating a cutoff state of the local cleaning device when contamination occurs.
FIG. 12 is a diagram showing a situation in which a rapid downflow is caused in a local cleaning device in which contamination has occurred.
FIG. 13 is a diagram illustrating a state in which a downflow is gradually generated in a local cleaning device in which contamination has occurred.
FIG. 14 is a diagram illustrating an example of a state in which contamination occurs in one of a plurality of connected local cleaning devices.
FIG. 15 is a diagram showing an example of a state in which a cleaning area inside one of the connected local cleaning devices is connected to outside air and contamination has occurred.
[Explanation of symbols]
1 Pollution propagation prevention system
2 Work
3 module (local cleaning device)
4 Connection path
16 fan (clean air generating means)
17 Filter (clean air generating means)
19 Exhaust fan (exhaust means)
C Clean area

Claims (8)

In a contamination propagation prevention system in a manufacturing system that forms a clean area by connecting a plurality of local cleaning devices that perform predetermined manufacturing processes such as work assembly and processing by a tubular connection path, and realizes a series of clean manufacturing processes, In the local cleaning device or the connection path, at least one of a contamination occurrence detection unit that detects contamination occurring in a clean area inside the system or a contamination occurrence prediction unit that predicts the occurrence of contamination, and another of the generated contamination. A pollution propagation prevention system comprising: a pollution propagation prediction unit for predicting propagation to a local cleaning device; and a pollution propagation preventing unit for preventing propagation of generated contamination to another local cleaning device. 2. The pollution propagation prevention system according to claim 1, wherein said pollution occurrence prediction means is means for predicting the occurrence of pollution based on information on a flow velocity and a flow direction of air in said connection path. 2. The pollution propagation prevention system according to claim 1, wherein said pollution propagation prediction means is means for predicting propagation of pollution based on information on a flow velocity and a flow direction of air in said connection path. The contamination propagation preventing means includes a local cleaning device connected to the local cleaning device based on information on a local cleaning device in which contamination is detected or predicted and information on a flow velocity and a flow direction of air in a connection channel connected to the local cleaning device. 2. The pollution propagation preventing system according to claim 1, wherein the system controls a clean air generating unit provided in the apparatus. Defective discharge or removal of workpieces that existed in the local cleaning device where contamination was detected or predicted and that existed in a predetermined number of local cleaning devices or connection paths sequentially connected upstream or downstream from the local cleaning device. The contamination propagation prevention system according to claim 1, wherein re-cleaning is performed. The production of a workpiece existing in a process further downstream than a predetermined number of local cleaning devices sequentially connected downstream from the local cleaning device in which contamination is detected or predicted continues, and the local cleaning device in which the contamination is detected or predicted. The contamination propagation prevention system according to claim 1, wherein manufacturing of a workpiece in a predetermined local cleaning device sequentially connected upstream from the local cleaning device is interrupted. The contamination propagation prevention system according to claim 1, further comprising a cleanliness recovery unit for recovering the cleanliness of the local cleaning device or the connection path that has been detected or predicted from contamination. The cleanliness recovery unit includes a clean air generating unit and an exhaust unit that exhausts the local cleaning device. The prevention of the propagation of contamination is connected to the local cleaning device in which contamination is detected or predicted and the local cleaning device. The cleaning is performed by reducing the flow rate of the clean air from the clean air generating means provided in the local cleaning device connected to the connection path based on the information on the flow velocity and the flow direction of the air in the connection path. 8. The method according to claim 7, wherein the recovery of the degree is performed by gradually increasing the flow rate of the reduced clean air from the clean air generating means to a flow rate necessary for ensuring the cleanliness of the clean area. The contamination propagation prevention system as described.

Images