JP2023150825A - Thread breakage detection device of sewing machine - Google Patents

Abstract

To effectively prevent deterioration of work efficiency in sewing, by surely detecting thread breakage of a looper thread when operating a sewing machine, and by quickly stopping the sewing machine operation at the time of thread breakage of the looper thread.SOLUTION: A thread breakage detection device includes: an optical sensor which is in the middle of a path of a looper thread held by a thread winding cam and a looper, and in which an optical axis is directed at one of a front, rear, left and right directions; and an optical sensor weft thread guide member which includes two thread passing holes where the looper threads are inserted on both lateral sides of the optical sensor, in which the direction of the central line of the two thread passing holes is the same as the direction crossing the direction of the optical axis of the optical sensor, and which includes a space which, when the thread is loosened on the thread passing hole side closer to the looper out of the two thread passing holes, falls by the self-weight of the thread in the lower direction than the line connecting the lowermost ends of the holes between the two thread passing holes.SELECTED DRAWING: Figure 1

Description

本発明は、二重環縫い目を形成するミシンのルーパー糸の糸切れ検知装置に関するものである。本発明において、前後とは布送り方向における前後方向をいい、左右とはミシンを正面から見たときの左右方向をいう。また上下とはミシンの上下方向をいう。 The present invention relates to a looper thread breakage detection device for a sewing machine that forms a double chainstitch. In the present invention, "back and forth" refers to the front and rear directions in the cloth feeding direction, and "left and right" refers to the left and right directions when the sewing machine is viewed from the front. Also, "up and down" refers to the up and down direction of the sewing machine.

針を挟んで左右に往復運動するルーパーを備え、針とルーパーとの協働により二重環縫い目を形成するミシンでは通常、ルーパーの手前でルーパー糸を挿通した２つの糸案内間に糸繰りカムを設置し、糸繰りカムの輪郭の曲線にルーパー糸を接触させることにより変化する張力を与えルーパー糸の繰り出し量を多くしたり少なくしたりするようにしている。ところがミシン稼働中にルーパー糸が切れたり、縫製作業の前後においてルーパー糸を切断した後にミシンを再稼働するときに、ルーパー糸がルーパーから外れて糸繰りカム回転軸に巻き付くといった不具合が生じることがある。糸繰りカム回転軸へのルーパー糸の巻き付きに作業者が気付かないでそのままミシン稼働が続けられるとルーパー糸が供給源側から引き出されて巻き付きの量が増大する。これを取り除くために作業者はミシンを停止させて安全を確認しながら手で低速で逆回転させて巻き付いたルーパー糸を引っ張って取り外すといった作業が発生する。例えば１秒間で１００回転する回転数のミシンで３秒間の巻き付きが生じれば３００回転分を手で逆回転させることになりミシン自体のトルクも相まって作業者に大きな負担を与え作業能率を非常に低下させることがあった。さらに筒状物を縫製するためのシリンダベッドミシンでは、糸繰りカムが設置されているスペースが狭いため巻き付いたルーパー糸の除去作業が大変困難であった。 A sewing machine that is equipped with a looper that moves back and forth from side to side with the needle in between, and that forms a double chain stitch by the cooperation of the needle and the looper, usually has a thread take-up cam installed between two thread guides through which the looper thread is inserted before the looper. By bringing the looper yarn into contact with the curve of the outline of the thread reeling cam, variable tension is applied to increase or decrease the amount of the looper yarn being fed out. However, problems may occur such as the looper thread breaking while the sewing machine is in operation, or when restarting the sewing machine after cutting the looper thread before or after sewing work, the looper thread comes off the looper and wraps around the thread take-up cam rotation shaft. be. If the sewing machine continues to operate without the operator noticing that the looper thread is wrapped around the thread take-up cam rotating shaft, the looper thread will be pulled out from the supply source and the amount of wrapping will increase. To remove this, the worker has to stop the sewing machine, check to make sure it is safe, and manually rotate the sewing machine in the reverse direction at low speed to pull and remove the looper thread that has become wrapped around it. For example, if a sewing machine that rotates at 100 revolutions per second is wrapped for 3 seconds, the user will have to rotate 300 revolutions in the opposite direction by hand, which, combined with the torque of the sewing machine itself, places a heavy burden on the worker and greatly reduces work efficiency. It could be lowered. Furthermore, in cylinder bed sewing machines for sewing cylindrical objects, the space in which the thread take-up cam is installed is narrow, making it extremely difficult to remove the looper thread that has become wrapped around the machine.

糸繰りカムに糸が巻き付くことを防止するために糸を監視する方法としてミシンの糸切れ検知装置が知られている。（例えば、特許文献１参照。）糸切れ検知装置は糸繰りカムとルーパーとの間のルーパー糸経路上に固定配置され、ルーパー糸を挿通する糸通し孔を有する一対の糸道と、前記糸通し孔に挿通されたルーパー糸部の振動を前記糸道の間で監視するセンサと、該センサによる糸の振動無しの検知に基づいてミシン稼働を停止する。これは縫目が形成される際にルーパー側での糸消費によって動的に発生される糸の振動が糸通し孔に挿通された一対の糸道間でセンサにより監視される。このセンサによる糸の振動の監視でルーパー糸の糸切れが検知されるとともに、制御装置を介してミシン稼働が停止される。 2. Description of the Related Art A thread breakage detection device for a sewing machine is known as a method of monitoring thread in order to prevent the thread from being wrapped around a thread take-up cam. (For example, see Patent Document 1.) The thread breakage detection device is fixedly disposed on the looper thread path between the thread take-up cam and the looper, and includes a pair of thread paths each having a thread passage hole through which the looper thread is inserted, and a thread passage through which the looper thread is passed. A sensor monitors vibrations of the looper thread inserted through the hole between the thread paths, and operation of the sewing machine is stopped based on detection of no vibration of the thread by the sensor. This is because when a stitch is formed, vibrations of the thread dynamically generated due to thread consumption on the looper side are monitored by a sensor between a pair of thread paths inserted into the threading hole. By monitoring the vibration of the thread by this sensor, breakage of the looper thread is detected, and the operation of the sewing machine is stopped via the control device.

特開２００１－７０６８２号公報Japanese Patent Application Publication No. 2001-70682

前述の糸切れ検知装置では動的に発生するルーパー糸の振動の有無を監視しており、一対の糸道間で糸が残っている状態ではミシンが稼働していれば糸の振動が発生するため、例えばルーパー先端以降でルーパー糸が切断されて糸繰りカム回転軸に巻き付くことが始まってもしばらくの間糸は巻き付き続けて、一対の糸道の片側から糸が抜けてさらにセンサの光軸からが糸が交差しない所まで抜ける程度に糸が糸繰りカムに巻き付いた後でなければ正確に検知されないものであった。 The aforementioned thread breakage detection device monitors the presence or absence of vibrations in the looper thread that occur dynamically, and if thread remains between a pair of thread paths, thread vibration will occur if the sewing machine is operating. Therefore, for example, even if the looper thread is cut after the tip of the looper and begins to wrap around the thread take-up cam rotation shaft, the thread will continue to wrap around the thread take-up cam rotation shaft for a while, and the thread will come off from one side of the pair of thread paths, causing the sensor's optical axis to Accurate detection could only be made after the thread had been wrapped around the thread take-up cam to such an extent that the empty thread could no longer intersect.

本発明は、上記問題を解決するためになされたものでありその目的は、ミシン稼働時にルーパー糸の糸切れを検知するとともに、ルーパー糸の糸切れ時に糸繰りカム回転軸に巻き付く量を減らせるようにミシン稼働を素早く停止させ、縫製における作業者の負担の軽減と作業能率の低下を効果的に阻止できるミシンの糸切れ検知装置を提供することを目的としている。 The present invention has been made to solve the above problems, and its purpose is to detect breakage of looper thread when the sewing machine is operating, and to reduce the amount of looper thread wrapped around the thread take-up cam rotating shaft when the thread breaks. It is an object of the present invention to provide a thread breakage detection device for a sewing machine that can quickly stop the operation of the sewing machine, reduce the burden on the worker during sewing, and effectively prevent a decrease in work efficiency.

上記目的を達成するために、請求項１に記載の発明は、左右に往復運動するルーパーと、ルーパーの往復運動と連動する糸繰りカム回転軸に固定されルーパー糸の経路上に設置された糸繰り台からのルーパー糸の繰り出し量を変化させる糸繰りカムと、糸繰りカムの両側の糸繰り台上に配置され、ルーパー糸を挿通する糸道穴を有する糸案内とを備えたミシンにおいて、糸繰りカムとルーパーが保持するルーパー糸の経路の途中にあり光軸が前後左右方向いずれかに向かう光センサと、光センサの両横側でルーパー糸を挿通する２箇所の糸通し穴を備えており、２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴のうちルーパーに近い方の糸通し穴側にて糸が緩むときに、２箇所の糸通し穴の間で穴の最下端を結ぶ線より下方向に糸の自重で落ち込む空間を備える光センサ横糸道部材を設けたことを特徴とするものである。 In order to achieve the above object, the invention according to claim 1 includes a looper that reciprocates left and right, and a thread reel stand that is fixed to a rotating shaft of a thread reel cam that interlocks with the reciprocating motion of the looper and is installed on the path of the looper thread. In a sewing machine equipped with a thread take-up cam that changes the amount of the looper thread taken out from the thread take-up cam, and thread guides that are arranged on the thread take-up stand on both sides of the thread take-up cam and have thread guide holes through which the looper thread is inserted, the thread take-up cam and the looper are It is equipped with an optical sensor located in the middle of the path of the looper thread to be held and whose optical axis faces either the front, back, left or right direction, and two threading holes on both sides of the optical sensor through which the looper thread is inserted. The direction of the center line of the threading hole is the direction that intersects the direction of the optical axis of the optical sensor, and when the thread becomes loose at the threading hole side that is closer to the looper, The present invention is characterized in that an optical sensor weft guide member is provided between the threading holes, and has a space that falls under the weight of the thread in a direction below a line connecting the lowermost ends of the holes.

上記目的を達成するために、請求項２に記載の発明は、請求項１記載のミシンの糸切れ検知装置であって、前記光センサ横糸道部材は２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にあることを特徴とするものである。 In order to achieve the above object, the invention according to claim 2 provides a thread breakage detection device for a sewing machine according to claim 1, wherein the optical sensor weft thread guide member is arranged in the direction of the center line of two threading holes. is a direction that intersects with the direction of the optical axis of the optical sensor, and is characterized in that the vertical positions of the center lines of the two threading holes are below the optical axis of the optical sensor.

上記目的を達成するために、請求項３に記載の発明は、請求項１記載のミシンの糸切れ検知装置であって、前記光センサ横糸道部材は２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にあり、２箇所の糸通し穴の最上端を結ぶ線の上下位置が光軸に伴う検出範囲の内側にあることを特徴とするものである。 In order to achieve the above object, the invention according to claim 3 provides a thread breakage detection device for a sewing machine according to claim 1, in which the optical sensor weft thread guide member is arranged in the direction of the center line of two threading holes. is the direction that intersects with the direction of the optical axis of the optical sensor, the vertical position of the center line of the two threading holes is below the optical axis of the optical sensor, and the top ends of the two threading holes are connected. It is characterized in that the upper and lower positions of the line are inside the detection range along the optical axis.

上記目的を達成するために、請求項４に記載の発明は、請求項１または２または３記載のミシンの糸切れ検知装置であって、光軸に伴う検出範囲にルーパー糸が重なるときの検知信号と光軸に伴う検出範囲にルーパー糸が重ならないときの検知信号をそれぞれ監視して、ミシン稼働が開始したときに検知信号の監視を開始して、一定の時間間隔で二つの信号が切り替わることでミシン稼働が正常であると判断して、一定の時間間隔で二つの信号が切り替わらないとき異常が発生したと判断して、異常が発生したとの判断があらかじめ指定した一定の時間間隔の整数倍で連続して発生したときに誤検知でないと判断し異常であると判断してミシン稼働を停止させて、異常が発生したとの判断があらかじめ指定した一定の時間間隔の整数倍に達する前に二つの信号が切り替わることが生じれば誤検知であったとして正常であると判断する制御装置を設けた構成である。 In order to achieve the above object, the invention according to claim 4 provides a thread breakage detection device for a sewing machine according to claim 1, 2 or 3, which detects when a looper thread overlaps a detection range along an optical axis. The detection signal when the looper thread does not overlap with the signal and the detection range along the optical axis is monitored respectively, and the detection signal starts to be monitored when the sewing machine starts operating, and the two signals switch at a fixed time interval. Therefore, it is determined that the sewing machine is operating normally, and when the two signals do not switch at a certain time interval, it is determined that an abnormality has occurred. When the error occurs continuously at an integral multiple, it is determined that it is not a false positive, it is determined that it is an abnormality, and the sewing machine operation is stopped. This configuration includes a control device that determines that if two signals have previously switched, it is a false detection and that the detection is normal.

本発明によれば、ミシン稼働時に針とルーパーとにより縫目が形成され、このときルーパーのルーパー糸の消費とルーパー糸の保持による張力変化と、糸繰りカムのルーパー糸に与える張力変化により発生するルーパー糸の振動が、糸通し穴に挿通された光センサ横糸道部材間で光センサにより監視される。ルーパー糸の振動は複数の振動が合成されたものであり要因として主に二つ存在する。一つはミシン自体の機械振動がルーパー糸に伝達されて生じるものである。もう一つは前述の一対の糸道と同じ機能をもつ光センサ横糸道部材間にて、２箇所の糸通し穴と糸の接触部を節としてルーパー糸が弦振動を行うものである。 According to the present invention, a stitch is formed by the needle and the looper when the sewing machine is in operation, and at this time, the stitches are generated due to the consumption of the looper thread of the looper and the tension change caused by holding the looper thread, and the tension change applied to the looper thread by the thread take-up cam. Vibration of the looper thread is monitored by an optical sensor between the optical sensor weft guide members inserted through the threading holes. The vibration of the looper thread is a combination of multiple vibrations, and there are two main factors. One type is caused by the mechanical vibration of the sewing machine itself being transmitted to the looper thread. The other method is one in which the looper yarn string-vibrates between the optical sensor weft path members which have the same function as the pair of yarn paths described above, using the two threading holes and the contact portions of the yarn as nodes.

ミシン自体の機械振動は前後左右上下方向が組み合わさりルーパー糸へ強制振動を与える。強制振動の振動数はミシン稼働時の回転数と同じものが主要因となる。そして加振力の要因としては近傍にある糸繰りカムによるものの割合が大きい。弦振動はその固有振動数が節間の距離である弦の長さに反比例し張力の二分の一乗に比例することは良く知られている。例えば光センサ横糸道部材間の２箇所の糸通し穴が左右方向に設置される場合、２箇所の糸通し穴と糸の接触部を節としてルーパー糸は主に前後方向や上下方向に加振される。左側の糸通し穴での糸の張力の向きが左上方向、右側の糸通し穴での糸の張力の向きが右下方向のとき、節は左側の糸通し穴の上端と右側の糸通し穴の下端に生じる。糸の張力の向きはルーパー，糸切れ検知装置，糸繰り台の相対的な位置により決まる。２箇所の糸通し穴と糸の接触部を節としてルーパー糸をみたとき、節にて生じるルーパー糸の張力はミシン１回転中で様々に変化する。節間の距離はおおむね一定であるが張力が変化することにより弦振動の固有振動数がミシン稼働時の回転数に等しく又は近くなれば強制振動に加えてルーパー糸に弦振動の固有振動又はこれに近い合成振動が生じる。このときルーパー糸の振幅は最も大きくなると考えられる。 The mechanical vibrations of the sewing machine itself are combined in the front, back, left, right, top and bottom directions and give forced vibrations to the looper thread. The main factor for the frequency of forced vibration is the same as the rotational speed when the sewing machine is operating. A large proportion of the excitation force is due to the thread reeling cam located nearby. It is well known that the natural frequency of string vibration is inversely proportional to the length of the string, which is the distance between nodes, and proportional to the 1/2 power of the tension. For example, when two threading holes between the optical sensor weft path member are installed in the left and right direction, the looper thread is mainly vibrated in the front-rear direction and the vertical direction using the contact points between the two threading holes and the thread as nodes. be done. When the direction of thread tension in the left threading hole is in the upper left direction and the direction of thread tension in the right threading hole is in the lower right direction, the node will be located between the top of the left threading hole and the right threading hole. Occurs at the lower end of. The direction of thread tension is determined by the relative positions of the looper, thread breakage detector, and thread take-up stand. When looking at the looper thread with the contact points between the two threading holes and the thread as knots, the tension of the looper thread generated at the knots changes variously during one rotation of the sewing machine. Although the distance between the nodes is approximately constant, if the tension changes and the natural frequency of the string vibration becomes equal to or close to the number of rotations when the sewing machine is operating, the looper thread will experience the natural vibration of the string vibration or this frequency in addition to the forced vibration. A synthetic vibration close to that occurs. At this time, the amplitude of the looper yarn is considered to be the largest.

従来の技術でのミシンの糸切れ検知装置は光センサの光軸の向きを前後方向にして２箇所の糸通し穴の中心線の向きを左右方向とした場合に、光センサの光軸と２箇所の糸通し穴の中心線の上下位置を一致させて、前述の糸の強制振動と弦振動の合成振動について有無を検知する。（図３に正常なミシン稼働時の糸の弦振動の模式図を記す。） Conventional thread breakage detection devices for sewing machines are designed so that when the optical axis of the optical sensor is oriented in the front-back direction and the center line of the two threading holes is oriented in the left-right direction, the optical axis of the optical sensor and the 2 By aligning the vertical positions of the center lines of the threading holes at the locations, the presence or absence of the composite vibration of the forced vibration of the thread and the string vibration is detected. (Figure 3 shows a schematic diagram of thread string vibration during normal sewing machine operation.)

光センサによる糸の振動の検知の制御としては例えば以下の方法を用いることができる。光軸に伴う検出範囲に糸が重なるときの検知信号と糸が重ならない時の検知信号との切り替わりが発生することで糸の振動が生じていることを確認し正常に糸が供給されていると判断する。光軸に伴う検出範囲に糸が重ならない時の検知信号が継続すると切り替わりが生じないためこの状態が一定時間経過すれば異常が発生したと判断する。光軸に伴う検出範囲に糸が重なるときの検知信号が継続するときも同様に異常が発生したと判断する。これらにより異常が発生したことの判断が開始される。そしてこの状態が一定時間経過すれば誤検知でなく異常であると判断されミシン稼働が停止される。 For example, the following method can be used to control the detection of yarn vibration by the optical sensor. It is confirmed that the thread is vibrating by switching between the detection signal when the thread overlaps in the detection range associated with the optical axis and the detection signal when the thread does not overlap, and the thread is being fed normally. I judge that. If the detection signal when the thread does not overlap with the detection range along the optical axis continues, switching will not occur, and if this state continues for a certain period of time, it is determined that an abnormality has occurred. Similarly, it is determined that an abnormality has occurred when the detection signal when the thread overlaps the detection range along the optical axis continues. Based on these, a determination as to whether an abnormality has occurred is started. If this state continues for a certain period of time, it is determined that this is not an erroneous detection but an abnormality, and the sewing machine operation is stopped.

しかし従来の技術ではルーパー先端でルーパー糸の糸切れが生じた場合、最初はルーパー内で残されたルーパー糸の部分と２箇所の糸通し穴の間のルーパー糸の部分は強制振動により加振されており検知信号の切り替わりが生じて正常に糸が供給されていると判断される。（図４にこのときの糸の強制振動の模式図を記す。）そしてルーパー糸が糸繰りカムに巻き付き始めてルーパー糸が引き戻され、ルーパー糸の切断された先端が２箇所の糸通し穴の間にある光軸に伴う検出範囲から抜けた所でようやく継続して糸が重ならない状態が生じる。したがって実際には糸繰りカムには、ルーパー先端から光軸に伴う検出範囲から抜けた所までの糸の経路にあるルーパー糸と、さらに誤検知でなく異常であると判断される一定時間の間に巻き付き続ける量の糸が糸繰りカムに巻き付くことになる。 However, with conventional technology, when the looper thread breaks at the tip of the looper, the part of the looper thread left inside the looper and the part of the looper thread between the two threading holes are first vibrated by forced vibration. When the detection signal changes, it is determined that the yarn is being fed normally. (Figure 4 shows a schematic diagram of the forced vibration of the thread at this time.) Then, the looper thread begins to wrap around the thread take-up cam, the looper thread is pulled back, and the cut end of the looper thread is placed between the two threading holes. A state in which the threads do not continue to overlap occurs only when the threads are out of the detection range associated with a certain optical axis. Therefore, in reality, the thread take-up cam contains the looper thread in the thread path from the looper tip to the point outside the detection range along the optical axis, and the looper thread in the thread path from the looper tip to the point outside the detection range along the optical axis. The amount of thread that continues to be wound around the thread take-up cam.

本発明の請求項１によれば、糸繰りカムに巻き付くルーパー糸の量を減らすために、糸繰りカムとルーパーが保持するルーパー糸の経路の途中にあり光軸が前後左右方向いずれかに向かう光センサと、光センサの両横側でルーパー糸を挿通する２箇所の糸通し穴を備えており、２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴のうちルーパーに近い方の糸通し穴側にて糸が緩むときに、２箇所の糸通し穴の間で穴の最下端を結ぶ線より下方向に糸の自重で落ち込む空間を備える光センサ横糸道部材を設けた構成とできる。これにより通常のミシン稼働時にはルーパー糸の弦振動で検知信号の切り替わりが生じる。 According to claim 1 of the present invention, in order to reduce the amount of looper thread wound around the thread take-up cam, a light beam is provided which is located in the middle of the path of the looper thread held by the thread take-up cam and the looper, and whose optical axis is directed in either the front, back, left or right direction. It is equipped with two threading holes for inserting the looper thread on both sides of the sensor and the optical sensor, and the direction of the center line of the two threading holes is in the direction that intersects with the direction of the optical axis of the optical sensor. , when the thread loosens in the threading hole that is closer to the looper, the weight of the thread will cause it to move downward from the line connecting the lowest end of the hole between the two threading holes. A configuration may be provided in which an optical sensor weft guide member is provided with a depressed space. As a result, during normal sewing machine operation, the detection signal changes due to string vibration of the looper thread.

ルーパー先端でルーパー糸の糸切れが生じた場合、ルーパー糸が糸繰りカムに巻き付き始めてルーパー糸が引き戻されるよりも先に、２箇所の糸通し穴のうちルーパーに近い側の糸通し穴の横でルーパー糸のルーパーによる張力を失い緩みが生じて糸繰りカムによる張力で２箇所の糸通し穴の間に引っ張られて下方向へ降りることで、ルーパー糸の振動は通常よりも下方で生じることになる。このときの振動はルーパーに近い側の糸通し穴でルーパー糸の張力が失われるため弦振動の一つの節としての機能を失い強制振動を主とするものになる。光センサはこの状態では光軸に伴う検出範囲に糸が重ならない時の検知信号のみとなり、切り替わりが生じないため異常が発生したことの判断が開始される。これによりルーパー糸が糸繰りカムに巻き付き始めてルーパー糸が引き戻され、ルーパー糸の切断された先端が２箇所の糸通し穴の間にある光軸に伴う検出範囲から抜けるよりも先に、一定時間経過して異常であると判断されてミシン稼働が停止する。したがって糸繰りカムには前述の従来の糸の振動を検知する方法よりも異常が発生したことの判断の開始が早いためルーパー糸の巻き付く量が少なくなる。 If the looper thread breaks at the tip of the looper, before the looper thread begins to wrap around the thread take-up cam and is pulled back, the looper thread should be cut next to the threading hole on the side closer to the looper of the two threading holes. The looper thread loses its tension due to the looper, becomes loose, and is pulled downward by the tension from the thread take-up cam between the two threading holes, causing the looper thread to vibrate lower than usual. . The vibration at this time loses tension in the looper thread at the threading hole on the side closer to the looper, so it loses its function as a node of string vibration and becomes mainly forced vibration. In this state, the optical sensor only generates a detection signal when the thread does not overlap the detection range along the optical axis, and since no switching occurs, it starts determining that an abnormality has occurred. As a result, the looper thread begins to wrap around the thread take-up cam, the looper thread is pulled back, and a certain period of time elapses before the cut end of the looper thread comes out of the detection range associated with the optical axis between the two threading holes. It is determined that there is an abnormality and the sewing machine stops operating. Therefore, the determination that an abnormality has occurred in the thread winding cam starts earlier than in the conventional method of detecting thread vibration, and the amount of looper thread wrapped around the thread winding cam is reduced.

また前記光センサ横糸道部材は２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にある構成とできる。これにより通常のミシン稼働時には、ルーパー糸の弦振動の振幅の最も上付近でのみ光軸に伴う検出範囲にルーパー糸が重なり、それ以外ではルーパー糸が重ならないことで検知信号の切り替わりが生じる。（図６にこのときの糸の弦振動の模式図を記す。） In addition, in the optical sensor weft thread guide member, the direction of the center line of the two threading holes is in a direction that intersects the direction of the optical axis of the optical sensor, and the upper and lower positions of the center line of the two threading holes are the direction in which the center line of the two threading holes is It can be configured below the axis. As a result, during normal sewing machine operation, the looper thread overlaps the detection range along the optical axis only near the top of the amplitude of the string vibration of the looper thread, and at other times the looper thread does not overlap, causing a switching of the detection signal. (Figure 6 shows a schematic diagram of the string vibration of the string at this time.)

前述の従来の技術では光センサの光軸と２箇所の糸通し穴の中心線の上下位置を一致させており、このときルーパー糸の弦振動の振幅の中心で光軸にルーパー糸が重なる。よって振幅の中心から上方向へ糸が振れるときに糸が重ならなくなることで検知信号の切り替わりが生じ、上方向から再び下方向へ糸が振れ始めて振幅の中心に来た時に糸が重なることで検知信号の切り替わりが生じ、下方向から再び上方向へ糸が振れ始めて振幅の中心に近づく。この過程を振動の１周期とすれば２分の１周期で１回の検知信号の切り替わりが生じる。これに対して本発明の技術ではルーパー糸の弦振動の振幅の最も上付近でのみ光軸に伴う検出範囲にルーパー糸が重なり、それ以外では光軸にルーパー糸が重ならないことにより振動の１周期で１回の検知信号の切り替わりが生じることになる。振動の１周期はミシン稼働時の回転数から換算することができる。例えば１秒間に１００回転の回転数であれば１００分の１秒を１周期としてこれを検知信号を監視する一定時間と指定することで検知信号の切り替わりを監視できる。しかしルーパー糸の糸繰りカムへの巻き付きを減らす目的において検知信号の監視に２分の１周期と１周期の違いがあっても糸の巻き付く量の違いは少ないため特段の問題はない。 In the above-mentioned conventional technology, the optical axis of the optical sensor and the center line of the two threading holes are aligned vertically, and at this time, the looper thread overlaps the optical axis at the center of the amplitude of the string vibration of the looper thread. Therefore, when the threads start swinging upward from the center of amplitude, the detection signals change because the threads no longer overlap, and when the threads start swinging downward from the top again and reach the center of the amplitude, the threads overlap. The detection signal switches, and the thread begins to swing from the bottom to the top again, approaching the center of amplitude. If this process is considered to be one cycle of vibration, one switching of the detection signal occurs in one-half cycle. On the other hand, with the technology of the present invention, the looper thread overlaps the detection range along the optical axis only near the top of the amplitude of string vibration of the looper thread, and at other times, the looper thread does not overlap with the optical axis, resulting in less vibration. This means that the detection signal switches once per cycle. One cycle of vibration can be calculated from the number of rotations when the sewing machine is in operation. For example, if the rotation speed is 100 revolutions per second, switching of the detection signal can be monitored by setting one-hundredth of a second as one cycle and specifying this period as a certain period of time for monitoring the detection signal. However, even if there is a difference between 1/2 period and 1 period in monitoring the detection signal for the purpose of reducing the winding of the looper yarn around the thread take-up cam, there is no particular problem because the difference in the amount of winding of the yarn is small.

そしてルーパー先端でルーパー糸の糸切れが生じた場合、前述の通りルーパー糸の振動は通常よりも下方で生じることになる。このときの振動はルーパーに近い側の糸通し穴でルーパー糸の張力が失われるため弦振動の一つの節としての機能を失い強制振動を主とするものになる。しかし緩んだルーパー糸が下方向で構造物に引っかかる等の何らかの抵抗を受けて張力が生じ弦振動の一つの節として機能する場合に上方向の振幅が本来の想定よりも大きくなることが考えられる。（図５にこのときの糸の弦振動の模式図を記す。） If the looper yarn breaks at the tip of the looper, the vibration of the looper yarn will occur at a lower position than usual, as described above. The vibration at this time loses tension in the looper thread at the threading hole on the side closer to the looper, so it loses its function as a node of string vibration and becomes mainly forced vibration. However, if the loosened looper string receives some kind of resistance, such as being caught on a structure in the downward direction, tension is generated and it functions as one node of string vibration, and the amplitude in the upward direction may become larger than originally expected. . (Figure 5 shows a schematic diagram of the string vibration of the string at this time.)

このときに光軸と２箇所の糸通し穴の中心線の上下位置が一致しているよりも２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にある方が上方向の振幅が光軸に伴う検出範囲と交差して検知信号の切り替わりが生じることが少なくなる。これによりルーパー糸が糸繰りカムに巻き付き始めてルーパー糸が引き戻され、ルーパー糸の切断された先端が２箇所の糸通し穴の間にある光軸に伴う検出範囲から抜けるよりも先に、一定時間経過して異常であると判断されてミシン稼働が停止する。したがって糸繰りカムには前述の従来の糸の振動を検知する方法よりもルーパー糸の巻き付く量が少なくなる。 At this time, if the vertical position of the center line of the two threading holes is lower than the optical axis of the optical sensor than the vertical position of the optical axis and the center line of the two threading holes are the same, The occurrence of switching of the detection signal due to the upward amplitude intersecting the detection range along the optical axis is reduced. As a result, the looper thread begins to wrap around the thread take-up cam, the looper thread is pulled back, and a certain period of time elapses before the cut end of the looper thread comes out of the detection range associated with the optical axis between the two threading holes. It is determined that there is an abnormality and the sewing machine stops operating. Therefore, the amount of looper yarn wrapped around the yarn winding cam is smaller than in the conventional method of detecting vibration of the yarn described above.

また前記光センサ横糸道部材は２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にあり、２箇所の糸通し穴の最上端を結ぶ線の上下位置が光軸に伴う検出範囲の内側にある構成とできる。これにより通常のミシン稼働時には、ルーパー糸の弦振動の振幅の中心付近もしくはこれより上で光軸にルーパー糸が重なる。（図８にこのときの糸の弦振動の模式図を記す。）そしてさらに上方向へ糸が振れるときに光軸に伴う検出範囲に糸が重ならなくなることで
検知信号の切り替わりが生じ、上方向から再び下方向へ糸が振れ始めて糸が重なることで検知信号の切り替わりが生じ、下方向から再び上方向へ糸が振れ始めて振幅の中心に近づく。これは２分の１周期で１回の検知信号の切り替わりが生じる。 In addition, in the optical sensor weft thread guide member, the direction of the center line of the two threading holes is in a direction that intersects the direction of the optical axis of the optical sensor, and the upper and lower positions of the center line of the two threading holes are the direction in which the center line of the two threading holes is It can be configured such that the upper and lower positions of a line that is located below the axis and connects the uppermost ends of the two threading holes are inside the detection range along the optical axis. As a result, during normal sewing machine operation, the looper thread overlaps the optical axis near or above the center of the amplitude of the string vibration of the looper thread. (Figure 8 shows a schematic diagram of the string vibration of the thread at this time.) Then, when the thread swings further upward, the detection signal changes as the thread no longer overlaps the detection range along the optical axis. The thread starts swinging downward again from the direction, and the threads overlap, causing a switch in the detection signal, and the thread starts swinging upward again from the downward direction, approaching the center of amplitude. This causes the detection signal to switch once in a half period.

そしてルーパー先端でルーパー糸の糸切れが生じた場合、前述の通りルーパー糸の振動は通常よりも下方で生じることになる。このときの振動はルーパーに近い側の糸通し穴でルーパー糸の張力が失われるため弦振動の一つの節としての機能を失い強制振動を主とするものになる。しかし緩んだルーパー糸が下方向で構造物に引っかかる等の何らかの抵抗を受けて張力が生じ弦振動の一つの節として機能する場合に上方向の振幅が本来の想定よりも大きくなることが考えられる。（図７にこのときの糸の弦振動の模式図を記す。） If the looper yarn breaks at the tip of the looper, the vibration of the looper yarn will occur at a lower position than usual, as described above. The vibration at this time loses tension in the looper thread at the threading hole on the side closer to the looper, so it loses its function as a node of string vibration and becomes mainly forced vibration. However, if the loosened looper string receives some kind of resistance, such as being caught on a structure in the downward direction, tension is generated and it functions as one node of string vibration, and the amplitude in the upward direction may become larger than originally expected. . (Figure 7 shows a schematic diagram of the string vibration of the string at this time.)

このときに光軸と２箇所の糸通し穴の中心線の上下位置が一致しているよりも２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にある方が上方向の振幅が光軸に伴う検出範囲と交差して検知信号の切り替わりが生じることが少なくなる。これによりルーパー糸が糸繰りカムに巻き付き始めてルーパー糸が引き戻され、ルーパー糸の切断された先端が２箇所の糸通し穴の間にある光軸に伴う検出範囲から抜けるよりも先に、一定時間経過して異常であると判断されてミシン稼働が停止する。したがって糸繰りカムには前述の従来の糸の振動を検知する方法よりもルーパー糸の巻き付く量が少なくなる。 At this time, if the vertical position of the center line of the two threading holes is lower than the optical axis of the optical sensor than the vertical position of the optical axis and the center line of the two threading holes are the same, The occurrence of switching of the detection signal due to the upward amplitude intersecting the detection range along the optical axis is reduced. As a result, the looper thread begins to wrap around the thread take-up cam, the looper thread is pulled back, and a certain period of time elapses before the cut end of the looper thread comes out of the detection range associated with the optical axis between the two threading holes. It is determined that there is an abnormality and the sewing machine stops operating. Therefore, the amount of looper yarn wrapped around the yarn winding cam is smaller than in the conventional method of detecting vibration of the yarn described above.

以上のように本発明によれば、ルーパー先端でルーパー糸の糸切れが生じた場合、ルーパー糸のルーパーによる張力を失い緩みが生じて下方向へ降りることで、ルーパー糸の振動は通常よりも下方で生じることになり、
これによりルーパー糸が糸繰りカムに巻き付き始めてルーパー糸が引き戻され、ルーパー糸の切断された先端が２箇所の糸通し穴の間にある光軸に伴う検出範囲から抜けるよりも先に、一定時間経過して異常であると判断されてミシン稼働が停止することで、ルーパー糸の巻き付く量が少なくなる。 As described above, according to the present invention, when the looper thread breaks at the tip of the looper, the looper thread loses its tension due to the looper, becomes loose, and descends downward, causing the looper thread to vibrate more than usual. It will occur below,
As a result, the looper thread begins to wrap around the thread take-up cam, the looper thread is pulled back, and a certain period of time elapses before the cut end of the looper thread comes out of the detection range associated with the optical axis between the two threading holes. When it is determined that there is an abnormality and the sewing machine stops operating, the amount of looper thread wrapped around the machine will be reduced.

また２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にあることで、上方向の振幅が本来の想定よりも大きくなる場合でも、検知信号の切り替わりが生じることが少なくなり、これによりルーパー糸が糸繰りカムに巻き付き始めてルーパー糸が引き戻され、ルーパー糸の切断された先端が２箇所の糸通し穴の間にある光軸に伴う検出範囲から抜けるよりも先に、一定時間経過して異常であると判断されてミシン稼働が停止することで、ルーパー糸の巻き付く量が少なくなる。したがって糸繰りカムに巻き付いた糸の除去が少なくて済み作業者の負担を減らし作業能率を向上させることができる。 In addition, because the vertical positions of the center lines of the two threading holes are below the optical axis of the optical sensor, the detection signal may switch even if the amplitude in the upward direction is larger than originally expected. decreases, and as a result, the looper thread begins to wrap around the thread take-up cam and is pulled back, before the cut end of the looper thread comes out of the detection range associated with the optical axis between the two threading holes. After a certain period of time has elapsed, it is determined that there is an abnormality and the sewing machine stops operating, thereby reducing the amount of looper thread wrapped around the machine. Therefore, it is possible to reduce the amount of thread wound around the thread take-up cam and to reduce the burden on the operator and improve work efficiency.

本発明に適用されるミシンの外観斜視図である。1 is an external perspective view of a sewing machine applied to the present invention. 本発明に適用されるミシンの平面図である。1 is a plan view of a sewing machine applied to the present invention. 従来のミシンの糸切れ検知装置の正面図であり、糸の弦振動の模式図である。FIG. 2 is a front view of a conventional thread breakage detection device of a sewing machine, and a schematic diagram of string vibration of thread. 従来のミシンの糸切れ検知装置の正面図であり、１箇所の糸通し穴側にて糸が緩むときの糸の強制振動の模式図である。It is a front view of a conventional thread breakage detection device of a sewing machine, and is a schematic diagram of forced vibration of the thread when the thread loosens at one thread threading hole side. 本発明に適用されるミシンの糸切れ検知装置の正面図であり、１箇所の糸通し穴側にて糸が緩むときの糸の弦振動の模式図である。It is a front view of the thread breakage detection device of the sewing machine applied to the present invention, and is a schematic diagram of the string vibration of the thread when the thread loosens at one thread threading hole side. 本発明に適用されるミシンの糸切れ検知装置の正面図であり、糸の弦振動の模式図である。1 is a front view of a thread breakage detection device for a sewing machine applied to the present invention, and is a schematic diagram of string vibration of thread. 本発明に適用されるミシンの糸切れ検知装置の正面図であり、１箇所の糸通し穴側にて糸が緩むときの糸の弦振動の模式図である。It is a front view of the thread breakage detection device of the sewing machine applied to the present invention, and is a schematic diagram of the string vibration of the thread when the thread loosens at one thread threading hole side. 本発明に適用されるミシンの糸切れ検知装置の正面図であり、糸の弦振動の模式図である。1 is a front view of a thread breakage detection device for a sewing machine applied to the present invention, and is a schematic diagram of string vibration of thread. 本発明に適用されるミシンの糸切れ検知装置の制御装置の流れ図である。1 is a flowchart of a control device for a thread breakage detection device of a sewing machine applied to the present invention.

以下図１から図８に基づいて本発明の実施形態を説明する。図１は本発明に適用されるミシンの外観斜視図であり、図２は同ミシンの平面図である。ミシン１は３本の針（図示なし）と１個のルーパー２とを備えており、糸供給源（図示なし）から糸調子器（図示なし）を経て供給される針糸（図示なし）と、同じく糸調子器を経て供給されるルーパー糸３とにより偏平縫いを形成する。各針は、ミシン１の稼働に連動して上下動する針棒（図示なし）に取り付けられ、針板（図示なし）の針穴を貫通する。ルーパー２は、ミシン１の稼働に連動して左右動するルーパー軸２１に取り付けられ、針板の針穴を貫通した各針の先端部を挟んで左右に往復運動する。 Embodiments of the present invention will be described below based on FIGS. 1 to 8. FIG. 1 is an external perspective view of a sewing machine to which the present invention is applied, and FIG. 2 is a plan view of the same sewing machine. The sewing machine 1 is equipped with three needles (not shown) and one looper 2, and the needle thread (not shown) is supplied from a thread supply source (not shown) through a thread tension device (not shown). , and the looper thread 3, which is also supplied via the thread tension device, forms interlock stitches. Each needle is attached to a needle bar (not shown) that moves up and down in conjunction with the operation of the sewing machine 1, and passes through a needle hole in a needle plate (not shown). The looper 2 is attached to a looper shaft 21 that moves left and right in conjunction with the operation of the sewing machine 1, and reciprocates left and right with the tip of each needle passing through the needle hole of the throat plate held therebetween.

ミシン１のシリンダ１１内には、主軸１２の回転に従って糸繰り台４からの繰り出し量が変化する糸繰りカム４１と、糸繰りカム４１の両横側の糸繰り台４上に配置される糸案内４２とが備えられている。糸繰り台４はシリンダ１１に固定され、糸繰りカム４１は主軸１２に固定され主軸１２に対して位相角を調節できる。糸案内４２はルーパー糸３を挿通するための糸道穴４３をそれぞれ有している。なお本実施の形態では糸繰りカムを主軸に固定しているがこれに限定されるだけでなく、ルーパーの往復運動と連動する糸繰りカム回転軸であれば何れの軸でもよい。 Inside the cylinder 11 of the sewing machine 1, there are a thread take-up cam 41 whose payout amount from the thread take-up stand 4 changes according to the rotation of the main shaft 12, and thread guides 42 arranged on the thread take-up stand 4 on both sides of the thread take-up cam 41. It is equipped. The thread reel 4 is fixed to the cylinder 11, and the thread reel cam 41 is fixed to the main shaft 12 so that the phase angle with respect to the main shaft 12 can be adjusted. The thread guides 42 each have a thread guide hole 43 through which the looper thread 3 is inserted. In this embodiment, the thread reeling cam is fixed to the main shaft, but the present invention is not limited to this, and any shaft may be used as long as the thread reeling cam rotates in conjunction with the reciprocating motion of the looper.

図５，図６は糸切れ検知装置５の正面図である。糸繰りカム４１とルーパー２間の糸経路上に糸切れ検知装置５が配置されている。糸切れ検知装置５はミシン１のシリンダ１１にネジ５１で固定される。糸切れ検知装置５は２箇所の糸通し穴５３を有する光センサ横糸道部材部材５２とフォトインタラプタ６とこれを搭載するセンサ基板６１とからなる。センサ基板６１は光センサ横糸道部材部材５２に基板固定ネジ６２で固定される。フォトインタラプタ６の光軸７は前記２箇所の糸通し穴５３の中心線の向きがフォトインタラプタ６の光軸７の向きと交わる方向であって、中心線の上下位置が光軸７よりも下側にある。図６では２箇所の糸通し穴５３を節としてルーパー糸３が弦振動を行った際に振幅の上方向側のみでルーパー糸３と光軸７が交差する位置にある様子を示している。なお図６中左のルーパー２側の糸の張力の向きを左上方向、図６中右の糸繰り台４側の糸の張力の向きを右下方向としている。この方向はルーパー２，糸切れ検知装置５，糸繰り台４の相対的な位置により決まる。ルーパー糸３の弦振動の振幅が最大となる固有振動数は、節の間にある弦の長さと糸の張力と糸の線密度の関係により定まり、２箇所の節の間の距離とミシン稼働時の回転数にて生じる最大の張力と標準的に使用される糸の線密度から関係を選択して、ミシン稼働時のルーパー糸３と光軸７が交差する位置を決定することができる。 5 and 6 are front views of the thread breakage detection device 5. A yarn breakage detection device 5 is arranged on the yarn path between the yarn winding cam 41 and the looper 2. The thread breakage detection device 5 is fixed to the cylinder 11 of the sewing machine 1 with a screw 51. The thread breakage detection device 5 includes an optical sensor weft guide member 52 having two threading holes 53, a photointerrupter 6, and a sensor board 61 on which it is mounted. The sensor board 61 is fixed to the optical sensor weft guide member 52 with board fixing screws 62. The optical axis 7 of the photo-interrupter 6 is such that the direction of the center line of the two threading holes 53 intersects with the direction of the optical axis 7 of the photo-interrupter 6, and the vertical position of the center line is below the optical axis 7. It's on the side. In FIG. 6, when the looper thread 3 performs string vibration using the two threading holes 53 as nodes, the looper thread 3 and the optical axis 7 intersect only on the upper side of the amplitude. Note that the direction of the tension of the thread on the looper 2 side on the left in FIG. 6 is in the upper left direction, and the direction of the tension on the thread on the right thread winding table 4 side in FIG. 6 is in the lower right direction. This direction is determined by the relative positions of the looper 2, thread breakage detection device 5, and thread take-up table 4. The natural frequency at which the amplitude of the string vibration of the looper thread 3 is maximum is determined by the relationship between the length of the string between the nodes, the tension of the thread, and the linear density of the thread, and the distance between the two nodes and the operation of the sewing machine. The position where the looper thread 3 and the optical axis 7 intersect when the sewing machine is in operation can be determined by selecting a relationship between the maximum tension generated at the rotational speed and the linear density of the thread normally used.

光センサ横糸道部材部材５２は２箇所の糸通し穴５３の間にフォトインタラプタ６およびセンサ基板６１が固定されており、２箇所の糸通し穴５３の間の下側には空間があり、挿通されたルーパー糸３が緩むときにルーパー糸３が２箇所の糸通し穴５３の間で穴の最下端を結ぶ線により下方向に糸の自重で落ち込むことができる大きさの空間である。図５では糸切れにてルーパー２の張力が失われて糸が緩んでルーパー２側にある糸通し穴５３の近傍で糸が自重で下方向に落ち込んだときのルーパー糸３の振動の様子を示している。このときルーパー糸３は振動しても光軸に伴う検出範囲７１と交差しない位置にある。 The photo-interrupter 6 and the sensor board 61 are fixed between two threading holes 53 in the optical sensor weft guide member 52, and there is a space below between the two threading holes 53 to allow insertion. This space is large enough to allow the looper thread 3 to fall downward under its own weight between the two threading holes 53 by a line connecting the lowest ends of the holes when the looper thread 3 loosens. Figure 5 shows how the looper thread 3 vibrates when the tension in the looper 2 is lost due to thread breakage, the thread becomes loose, and the thread falls downward under its own weight near the threading hole 53 on the looper 2 side. It shows. At this time, even if the looper thread 3 vibrates, it is at a position where it does not intersect the detection range 71 along the optical axis.

これにより通常のミシン稼働時には、ルーパー糸３の弦振動の振幅の最も上付近でのみ光軸に伴う検出範囲７１にルーパー糸３が重なりそれ以外ではルーパー糸３が重ならない。ルーパー２の先端でルーパー糸３の糸切れが生じた場合、ルーパー２内で残されたルーパー糸３と２箇所の糸通し穴５３の間のルーパー糸３は、ルーパー糸３が糸繰りカム４１に巻き付き始めてルーパー糸３が引き戻されるよりも先に、２箇所の糸通し穴５３のうちルーパー２に近い側の糸通し穴５３の横でルーパー糸３のルーパー２による張力を失い緩むことで糸繰りカム４１による張力で２箇所の糸通し穴５３の間に引っ張られて自重で下方向へ落ち込み、ルーパー糸３の振動は通常よりも下方で生じることになる。この状態ではミシン稼働していても光軸に伴う検出範囲７１にルーパー糸３が重ならない。 As a result, during normal sewing machine operation, the looper thread 3 overlaps the detection range 71 along the optical axis only near the top of the amplitude of the string vibration of the looper thread 3, and the looper thread 3 does not overlap at other times. When the looper thread 3 breaks at the tip of the looper 2, the looper thread 3 between the looper thread 3 left inside the looper 2 and the two threading holes 53 is Before the looper thread 3 starts winding and is pulled back, the looper thread 3 loses tension by the looper 2 and loosens next to the threading hole 53 on the side closer to the looper 2 out of the two threading holes 53, and the thread take-up cam 41, the looper thread 3 is pulled between the two threading holes 53 and falls downward under its own weight, and the vibration of the looper thread 3 occurs at a lower position than usual. In this state, even if the sewing machine is operating, the looper thread 3 does not overlap the detection range 71 along the optical axis.

図７，図８は糸切れ検知装置５の正面図である。糸繰りカム４１とルーパー２間の糸経路上に糸切れ検知装置５が配置されている。糸切れ検知装置５はミシン１のシリンダ１１にネジ５１で固定される。糸切れ検知装置５は２箇所の糸通し穴５３を有する光センサ横糸道部材部材５２とフォトインタラプタ６とこれを搭載するセンサ基板６１とからなる。センサ基板６１は光センサ横糸道部材部材５２に基板固定ネジ６２で固定される。フォトインタラプタ６の光軸７は前記２箇所の糸通し穴５３の中心線の向きがフォトインタラプタ６の光軸７の向きと交わる方向であって、中心線の上下位置が光軸７よりも下側にあり、２箇所の糸通し穴５３の最上端を結ぶ線の上下位置が光軸に伴う検出範囲７１の内側にある。このとき２箇所の糸通し穴５３を節としてルーパー糸３が弦振動を行った際に振幅の中心付近もしくはこれより上でルーパー糸３と光軸７が交差する。 7 and 8 are front views of the thread breakage detection device 5. A yarn breakage detection device 5 is arranged on the yarn path between the yarn winding cam 41 and the looper 2. The thread breakage detection device 5 is fixed to the cylinder 11 of the sewing machine 1 with a screw 51. The thread breakage detection device 5 includes an optical sensor weft guide member 52 having two threading holes 53, a photointerrupter 6, and a sensor board 61 on which it is mounted. The sensor board 61 is fixed to the optical sensor weft guide member 52 with board fixing screws 62. The optical axis 7 of the photo-interrupter 6 is such that the direction of the center line of the two threading holes 53 intersects with the direction of the optical axis 7 of the photo-interrupter 6, and the vertical position of the center line is below the optical axis 7. The upper and lower positions of the line connecting the uppermost ends of the two threading holes 53 are inside the detection range 71 along the optical axis. At this time, when the looper thread 3 performs string vibration using the two threading holes 53 as nodes, the looper thread 3 and the optical axis 7 intersect near or above the center of amplitude.

これにより通常のミシン稼働時には、ルーパー糸３の弦振動の振幅の中心付近もしくはこれより上で光軸に伴う検出範囲７１にルーパー糸３が重なりそれ以外ではルーパー糸３が重ならない。ルーパー２の先端でルーパー糸３の糸切れが生じた場合、ルーパー２内で残されたルーパー糸３と２箇所の糸通し穴５３の間のルーパー糸３は、ルーパー糸３が糸繰りカム４１に巻き付き始めてルーパー糸３が引き戻されるよりも先に、２箇所の糸通し穴５３のうちルーパー２に近い側の糸通し穴５３の横でルーパー糸３のルーパー２による張力を失い緩むことで糸繰りカム４１による張力で２箇所の糸通し穴５３の間に引っ張られて自重で下方向へ落ち込み、ルーパー糸３の振動は通常よりも下方で生じることになる。この状態ではミシン稼働していても光軸に伴う検出範囲７１にルーパー糸３が重ならない。 As a result, during normal sewing machine operation, the looper thread 3 overlaps the detection range 71 along the optical axis near or above the center of the amplitude of the string vibration of the looper thread 3, and the looper thread 3 does not overlap at other times. When the looper thread 3 breaks at the tip of the looper 2, the looper thread 3 between the looper thread 3 left inside the looper 2 and the two threading holes 53 is Before the looper thread 3 starts winding and is pulled back, the looper thread 3 loses tension by the looper 2 and loosens next to the threading hole 53 on the side closer to the looper 2 out of the two threading holes 53, and the thread take-up cam 41, the looper thread 3 is pulled between the two threading holes 53 and falls downward under its own weight, and the vibration of the looper thread 3 occurs at a lower position than usual. In this state, even if the sewing machine is operating, the looper thread 3 does not overlap the detection range 71 along the optical axis.

図９は糸切れ検知装置５の制御装置の流れ図である。制御装置はセンサ基板６１と接続されており、フォトインタラプタ６の光軸に伴う検出範囲７１にルーパー糸３が重なるときの検知信号と、光軸に伴う検出範囲７１にルーパー糸３が重ならないときの検知信号をそれぞれ監視している。ミシン稼働が開始したときに検知信号の監視を開始して、一定の時間間隔で二つの信号が切り替わることでミシン稼働が正常であると判断する。一定の時間間隔で二つの信号が切り替わらないとき異常が発生したと判断する。この異常が発生したとの判断があらかじめ指定した一定の時間間隔の整数倍で連続して発生したときに誤検知でないと判断し異常であると判断してミシン稼働を停止させる。異常が発生したとの判断があらかじめ指定した一定の時間間隔の整数倍に達する前に二つの信号が切り替わることが生じれば誤検知であったとして正常であると判断する。 FIG. 9 is a flowchart of the control device of the thread breakage detection device 5. The control device is connected to the sensor board 61, and receives a detection signal when the looper thread 3 overlaps the detection range 71 along the optical axis of the photointerrupter 6, and when the looper thread 3 does not overlap the detection range 71 along the optical axis. The detection signals of each are monitored. Monitoring of the detection signal is started when the sewing machine starts operating, and it is determined that the sewing machine is operating normally when the two signals switch at a fixed time interval. It is determined that an abnormality has occurred when the two signals do not switch at a fixed time interval. When this determination that an abnormality has occurred occurs continuously at an integer multiple of a predetermined fixed time interval, it is determined that it is not a false detection, an abnormality is determined, and the sewing machine operation is stopped. If the two signals switch before the determination that an abnormality has occurred reaches an integer multiple of a predetermined fixed time interval, it is determined to be a false detection and normal.

ルーパー２の先端でルーパー糸３の糸切れが生じた場合、光軸に伴う検出範囲７１にルーパー糸３が重ならないときの検知信号が連続して発するため、制御装置は前述の通り異常であると判断してミシン稼働を停止させる。 When the looper thread 3 breaks at the tip of the looper 2, the detection signal when the looper thread 3 does not overlap the detection range 71 along the optical axis is continuously emitted, so the control device is abnormal as described above. It is determined that this is the case and the sewing machine operation is stopped.

本発明は以上説明した実施例に限定されるものではなく、当業者であれば、本発明の趣旨を逸脱しない範囲で、前記実施例に種々の変更を付加して実施することができ、本発明はそれらの変更形態をも包含するものである。 The present invention is not limited to the embodiments described above, and those skilled in the art can implement various modifications to the embodiments described above without departing from the spirit of the invention. The invention also includes modifications thereof.

１ ミシン
２ ルーパー
３ ルーパー糸
４ 糸繰り台
５ 糸切れ検知装置
６ フォトインタラプタ
７ 光軸
１１ シリンダ
１２ 主軸（糸繰りカム回転軸）
２１ ルーパー軸
４１ 糸繰りカム
４２ 糸案内
４３ 糸道穴
５１ ネジ
５２ 光センサ横糸道部材
５３ 糸通し穴
６１ センサ基板
６２ 基板固定ネジ
７１ 光軸に伴う検出範囲 1 Sewing machine 2 Looper 3 Looper thread 4 Thread reeling stand 5 Thread breakage detection device 6 Photo interrupter 7 Optical axis 11 Cylinder 12 Main shaft (rotating shaft of thread reeling cam)
21 Looper shaft 41 Thread reeling cam 42 Thread guide 43 Thread guide hole 51 Screw 52 Optical sensor weft guide member 53 Threading hole 61 Sensor board 62 Board fixing screw 71 Detection range along optical axis

Claims (4)

左右に往復運動するルーパーと、ルーパーの往復運動と連動する糸繰りカム回転軸に固定されルーパー糸の経路上に設置された糸繰り台からのルーパー糸の繰り出し量を変化させる糸繰りカムと、糸繰りカムの両側の糸繰り台上に配置され、ルーパー糸を挿通する糸道穴を有する糸案内とを備えたミシンにおいて、
糸繰りカムとルーパーが保持するルーパー糸の経路の途中にあり光軸が前後左右方向いずれかに向かう光センサと、光センサの両横側でルーパー糸を挿通する２箇所の糸通し穴を備えており、２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴のうちルーパーに近い方の糸通し穴側にて糸が緩むときに、２箇所の糸通し穴の間で穴の最下端を結ぶ線より下方向に糸の自重で落ち込む空間を備える光センサ横糸道部材を特徴とするミシンの糸切れ検知装置。 A looper that reciprocates left and right, a thread take-up cam that is linked to the reciprocating movement of the looper, and a thread take-up cam that changes the amount of the looper thread taken out from a thread take-off stand that is fixed to the rotating shaft and installed on the path of the looper thread; A sewing machine equipped with a thread guide arranged on both thread winding stands and having a thread guide hole through which a looper thread is inserted,
It is equipped with a light sensor located in the middle of the path of the looper thread held by the thread take-up cam and the looper, with its optical axis pointing in either the front, back, left or right direction, and two threading holes on both sides of the light sensor through which the looper thread is inserted. When the center lines of the two threading holes intersect with the direction of the optical axis of the optical sensor, and the thread becomes loose at the threading hole that is closer to the looper. A thread breakage detection device for a sewing machine characterized by an optical sensor weft thread path member having a space between two threading holes that falls below a line connecting the lowest ends of the holes due to the weight of the thread. 前記光センサ横糸道部材は２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にあることを特徴とする請求項１記載のミシンの糸切れ検知装置。 In the optical sensor weft thread guide member, the direction of the center line of the two threading holes is in a direction that intersects with the direction of the optical axis of the optical sensor, and the upper and lower positions of the center line of the two threading holes are the optical axis of the optical sensor. 2. The thread breakage detection device for a sewing machine according to claim 1, wherein the thread breakage detection device is located below the thread breakage detection device. 前記光センサ横糸道部材は２箇所の糸通し穴の中心線の向きが光センサの光軸の向きと交わる方向であり、２箇所の糸通し穴の中心線の上下位置が光センサの光軸よりも下側にあり、２箇所の糸通し穴の最上端を結ぶ線の上下位置が光軸に伴う検出範囲の内側にあることを特徴とする請求項１記載のミシンの糸切れ検知装置。 In the optical sensor weft thread guide member, the direction of the center line of the two threading holes is in a direction that intersects with the direction of the optical axis of the optical sensor, and the upper and lower positions of the center line of the two threading holes are the optical axis of the optical sensor. 2. The thread breakage detection device for a sewing machine according to claim 1, wherein the upper and lower positions of a line connecting the uppermost ends of the two threading holes are located inside a detection range along the optical axis. 光軸に伴う検出範囲にルーパー糸が重なるときの検知信号と光軸に伴う検出範囲にルーパー糸が重ならないときの検知信号をそれぞれ監視して、ミシン稼働が開始したときに検知信号の監視を開始して、一定の時間間隔で二つの信号が切り替わることでミシン稼働が正常であると判断して、一定の時間間隔で二つの信号が切り替わらないとき異常が発生したと判断して、異常が発生したとの判断があらかじめ指定した一定の時間間隔の整数倍で連続して発生したときに誤検知でないと判断し異常であると判断してミシン稼働を停止させて、異常が発生したとの判断があらかじめ指定した一定の時間間隔の整数倍に達する前に二つの信号が切り替わることが生じれば誤検知であったとして正常であると判断する制御装置を設けたことを特徴とする請求項１または２または３記載のミシンの糸切れ検知装置。 The detection signal when the looper thread overlaps the detection range associated with the optical axis and the detection signal when the looper thread does not overlap the detection range associated with the optical axis are monitored, and the detection signal is monitored when the sewing machine starts operating. When the sewing machine starts and the two signals switch at a fixed time interval, it is determined that the sewing machine is operating normally, and when the two signals do not switch at a fixed time interval, it is determined that an abnormality has occurred. When the error occurs continuously at an integer multiple of a certain time interval specified in advance, it is determined that it is not a false positive, it is determined that there is an abnormality, the sewing machine operation is stopped, and the abnormality is determined to have occurred. A claim characterized in that a control device is provided which determines that if the two signals switch before the determination reaches an integral multiple of a predetermined fixed time interval, it is a false detection and is determined to be normal. Thread breakage detection device for a sewing machine according to 1, 2 or 3.

Images