JP5067550B2 - Pinhole inspection method for plastic bottles - Google Patents

Pinhole inspection method for plastic bottles Download PDF

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JP5067550B2
JP5067550B2 JP2007279983A JP2007279983A JP5067550B2 JP 5067550 B2 JP5067550 B2 JP 5067550B2 JP 2007279983 A JP2007279983 A JP 2007279983A JP 2007279983 A JP2007279983 A JP 2007279983A JP 5067550 B2 JP5067550 B2 JP 5067550B2
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bottle
pressure
threshold value
pinhole
internal pressure
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JP2009109259A (en
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洋祐 松下
登 澤根
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Toyo Seikan Kaisha Ltd
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Toyo Seikan Kaisha Ltd
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Priority to JP2007279983A priority Critical patent/JP5067550B2/en
Priority to KR20107008271A priority patent/KR101485888B1/en
Priority to CN200880113734.3A priority patent/CN101842682B/en
Priority to PCT/JP2008/069646 priority patent/WO2009057636A1/en
Priority to US12/739,581 priority patent/US8713993B2/en
Priority to EP08845905.2A priority patent/EP2213997B1/en
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Description

本発明は、合成樹脂製ボトルのピンホール検査方法、特にブロー成形された合成樹脂製ボトルのピンホール検査において、従来のピンホール検査に比してボトルのピンホールを好適に検出することができ、合成樹脂製ボトルのピンホール検査精度の向上を図ることが可能な合成樹脂製ボトルのピンホール検査方法に関する。   INDUSTRIAL APPLICABILITY The present invention can detect a pinhole in a bottle as compared with a conventional pinhole inspection in a pinhole inspection method for a synthetic resin bottle, particularly in a pinhole inspection of a blown synthetic resin bottle. The present invention relates to a pinhole inspection method for a synthetic resin bottle capable of improving the pinhole inspection accuracy of the synthetic resin bottle.

合成樹脂製ボトル、特にＰＥＴボトルは、軽量で取扱いが簡便であることなどを理由に、飲料、食品等の容器として近年大量に生産されている。
このＰＥＴボトルは、先ずプリフォームと呼ばれる一次成形品を射出成形等によって製造し、次いでこのプリフォームを所定の金型にセットし、そしてヒータ等の加熱手段によって配向延伸可能な温度まで加熱し、次いで高圧エアを噴射する延伸ロッドをプリフォームの内部に挿入し、延伸ロッドと高圧エアにより二軸に延伸する、いわゆる二軸延伸ブロー成形法により得られる。このように、二軸延伸ブロー成形法は加熱したプリフォームを延伸ロッドにより軸方向とそれと直交する方向の二軸に延伸するため、微妙な加工力（延伸力）の違いや樹脂材料中への極小の異物の混入などにより、ＰＥＴボトルは、ピンホールや亀裂等の欠陥を伴って製造される場合がある。従って、ブロー成形後のＰＥＴボトルに対しては、ピンホール等の欠陥が生じているか否かの検査を実施する必要がある。その為の検査方法としては、メインロータの外周に沿って把持されたＰＥＴボトルに対して、加圧ヘッドをボトル口部に当接してボトルの内部にエアを充填・密封し、そのエア密封状態をある一定時間保持し、その一定時間経過後のボトル内圧の圧力低下量から、ピンホールが生じているか否かを判定するピンホール検査方法が知られている（例えば、特許文献１および特許文献２を参照。）。
図９は、従来の圧力低下量からピンホールの有無を判定するピンホール検査方法を示すグラフである。縦軸がボトル内圧[kPa]を示し、横軸がバルブのシーケンス／時間[sec]を示している。
このピンホール検査方法は、例えば時刻Ｔ＝t0に供給バルブを開とし、エアをボトルの内部に供給する。次に時刻Ｔ＝t1に供給バルブを閉とし、エアの供給を停止し所定量のエアをボトルに密封する。そして時刻Ｔ＝t2までの間、そのエア密封状態を保持（ホールド）する。もし、ボトルにピンホール等のボトルの密封性を阻害する欠陥が存在する場合は、ボトル内部のエアがその欠陥を通して外部に流出し、それに応じてボトル内圧が低下する。ところで、時間の経過と共にボトル内部の温度が徐々に低下しそれに比例してボトル内圧も低下する。加えて、内圧上昇によりボトルの胴部が外方に若干膨らむことによってもボトル内圧は低下する。つまり、ピンホール等が存在しないボトルであってもボトル内圧は時間の経過と共にある程度低下する。そこで、温度低下等の非ピンホールに起因する圧力低下量を閾値ΔP0として予め規定しておき、時刻Ｔ＝t1からt2までの圧力低下量をその閾値ΔP0で検査する。そして、圧力低下量がその閾値ΔP0を超えていなければ、そのボトルは良品と判定される。一方、圧力低下量が閾値ΔP0を超えている場合は、そのボトルは不良品と判定されることになる。例えば、ボトル１では、圧力低下量ΔP1が閾値ΔP0を超えていないので、ボトル１はピンホール等の欠陥が存在しない良品と判定される。一方、ボトル２では、圧力低下量ΔP2がその閾値ΔP0を超えているので、ボトル２はピンホール等の欠陥が存在する不良品と判定される。そして時刻Ｔ＝t2にボトル内部のエアを排気し、所定時間が経過した時刻Ｔ＝t3でピンホール検査を終了する。良品と判定されたボトルは胴部が元の形状に復元し搬送装置により次工程である殺菌充填工程へ搬送される。一方、不良品と判定されたＰＥＴボトルは取り除かれて次工程へは搬送されないことになる。 Synthetic resin bottles, particularly PET bottles, have been produced in large quantities in recent years as containers for beverages, foods, and the like because they are lightweight and easy to handle.
In this PET bottle, first, a primary molded product called a preform is manufactured by injection molding or the like, then this preform is set in a predetermined mold, and heated to a temperature at which it can be oriented and stretched by heating means such as a heater, Next, a stretch rod for injecting high-pressure air is inserted into the preform and stretched biaxially with the stretch rod and the high-pressure air. Thus, in the biaxial stretch blow molding method, the heated preform is stretched in the axial direction and biaxially in the direction perpendicular to the stretched rod by the stretching rod, so that a subtle difference in processing force (stretching force) PET bottles may be manufactured with defects such as pinholes and cracks due to extremely small foreign matter. Therefore, it is necessary to inspect whether or not defects such as pinholes have occurred on the PET bottle after blow molding. As an inspection method therefor, for the PET bottle gripped along the outer periphery of the main rotor, the pressure head is brought into contact with the bottle mouth to fill and seal the inside of the bottle, and the air sealed state Is known for a pinhole inspection method for determining whether or not a pinhole has occurred from the amount of pressure drop of the bottle internal pressure after the predetermined time has elapsed (for example, Patent Document 1 and Patent Document 1) 2).
FIG. 9 is a graph showing a conventional pinhole inspection method for determining the presence or absence of a pinhole from the pressure drop amount. The vertical axis represents bottle internal pressure [kPa], and the horizontal axis represents valve sequence / time [sec].
In this pinhole inspection method, for example, the supply valve is opened at time T = t 0 to supply air into the bottle. Then the supply valve at time T = t 1 is closed, to seal the bottle a predetermined amount of air to stop the supply of air. And until time T = t 2 , the air-sealed state is held. If the bottle has a defect such as a pinhole that hinders the sealing performance of the bottle, the air inside the bottle flows out through the defect, and the internal pressure of the bottle decreases accordingly. By the way, the temperature inside the bottle gradually decreases with the passage of time, and the bottle internal pressure also decreases in proportion thereto. In addition, the bottle internal pressure also decreases when the body of the bottle slightly bulges outward due to the increase in internal pressure. That is, even if the bottle has no pinhole or the like, the internal pressure of the bottle decreases to some extent with time. Therefore, the amount of pressure drop caused by non-pinholes such as temperature drop is defined in advance as a threshold value ΔP 0 , and the pressure drop amount from time T = t 1 to t 2 is inspected with the threshold value ΔP 0 . If the pressure drop amount does not exceed the threshold value ΔP 0 , the bottle is determined to be non-defective. On the other hand, if the pressure drop amount exceeds the threshold value ΔP 0 , the bottle is determined to be defective. For example, the bottle 1, the pressure reduction amount [Delta] P 1 does not exceed the threshold value [Delta] P 0, the bottle 1 is judged to be good the defects such as pinholes are not present. On the other hand, in the bottle 2, since the pressure drop amount ΔP 2 exceeds the threshold value ΔP 0 , the bottle 2 is determined to be a defective product having defects such as pinholes. Then, the air inside the bottle is exhausted at time T = t 2 , and the pinhole inspection is terminated at time T = t 3 when a predetermined time has elapsed. The bottle determined to be non-defective is restored to its original shape by the body part and is transported to the next sterilization and filling process by the transport device. On the other hand, the PET bottle determined to be defective is removed and not transported to the next process.

特開２００４−２０５４５３号公報JP 2004-205453 A 特開２００２−３１０８４３号公報JP 2002-310843 A

当然のことではあるが、ピンホールが存在するボトル３の時刻Ｔ＝t1におけるエア密封直後のボトル内圧は、他のピンホールが存在しない良品ボトル（ボトル１）の内圧に比べ、低くなる。この傾向は、胴部の肉厚が従来のボトルより薄くされた計量薄肉ボトルでより顕著になってくる。
しかし、ボトル３の圧力低下量ΔP3について見みると、エアの密封直後のボトル内圧が小さいため、ピンホール等から漏れ出すエアの流出量も少ない。その結果、Ｔ＝t1からt2までの圧力低下量ΔP3は閾値ΔP0を超えない場合が起こり得る。この場合は、このボトル３はピンホールがあるにもかかわらず、上記従来の検査方法においては良品と判定されてしまう恐れがある。
そこで、本発明は、かかる従来技術の問題点に鑑みなされたものであって、ブロー成形された合成樹脂製ボトルのピンホール検査において、従来のピンホール検査に比してボトルのピンホールを好適に検出することができ、合成樹脂製ボトルのピンホール検査精度の向上を図ることが可能な合成樹脂製ボトルのピンホール検査方法を提供することにある。 As a matter of course, the bottle internal pressure immediately after air sealing at time T = t 1 of the bottle 3 in which the pinhole is present is lower than the internal pressure of the non-defective bottle (bottle 1) in which no other pinhole is present. This tendency becomes more prominent in a measurement thin wall bottle in which the thickness of the body portion is made thinner than that of a conventional bottle.
However, looking at the pressure drop amount ΔP 3 of the bottle 3, since the bottle internal pressure immediately after air sealing is small, the outflow amount of air leaking from the pinhole or the like is small. As a result, the pressure drop amount ΔP 3 from T = t 1 to t 2 may not exceed the threshold value ΔP 0 . In this case, there is a possibility that the bottle 3 may be determined to be non-defective in the conventional inspection method even though the bottle 3 has a pinhole.
Therefore, the present invention has been made in view of the problems of the prior art, and in pinhole inspection of blow molded synthetic resin bottles, the pinhole of the bottle is more suitable than conventional pinhole inspection. Another object of the present invention is to provide a method for inspecting a pinhole of a synthetic resin bottle that can be detected easily and can improve the pinhole inspection accuracy of the synthetic resin bottle.

前記目的を達成するために請求項１に記載の発明は、ブロー成形された合成樹脂製ボトルにガスを注入し、ボトルの内の圧力を計測して閾値と比較することでピンホールの有無を判定する合成樹脂製ボトルのピンホール検査方法であって、前記閾値が、注入されるガスの圧力に基づいて規定される第１閾値と、温度低下およびボトル変形に基づいて規定される第２閾値からなり、前記ボトルにガスを密封する工程と、密封直後の該ボトル内圧を基準内圧として計測し、該基準内圧が予め規定した第１閾値を超えているか否かをチェックする工程と、該基準内圧が該第１閾値を超えている場合は、該ボトルの密封状態を一定時間保持する工程と、一定時間経過後の該ボトル内圧の前記基準内圧からの圧力低下量を計測する工程と、計測した該圧力低下量が予め規定した第２閾値以内であるか否かをチェックする工程とを備え、前記基準内圧が前記第１閾値を超えており且つ前記圧力低下量が前記第２閾値を超えていない場合に限り、前記ボトルはピンホールのない良品と判定することを特徴とする。
上記合成樹脂製ボトルのピンホール検査方法では、所定量のガスを密封した直後のボトル内圧を基準内圧として、その基準内圧に基づいて閾値（第１閾値）を設定し、その第１閾値を超えていないボトルは不良品としてふるい落され、それ以降の圧力ホールド等の工程は全て実施されない。一方、第１閾値を超えたボトルは次工程の圧力ホールド、圧力低下量の計測が順に行われ、そして圧力低下量が温度低下およびボトル変形に基づいて規定される第２閾値を超えていない場合はそのボトルは最終的に良品として判定される。このように、圧力低下量計測における基準内圧に対しても第２閾値を設けることにより、ピンホールの存在する不良品ボトルを確実にふるい落とすことが出来るようになる。 In order to achieve the above-mentioned object, the invention described in claim 1 injects gas into a blow molded synthetic resin bottle, measures the pressure in the bottle, and compares it with a threshold value to determine the presence or absence of a pinhole. A pinhole inspection method for a synthetic resin bottle to be determined , wherein the threshold value is defined based on a pressure of an injected gas, and a second threshold value defined based on a temperature drop and bottle deformation. from it, a step of sealing gas into the bottle, a step of the bottle inner pressure immediately after sealing is measured as a reference pressure, to check whether the reference inner pressure exceeds the first threshold value defined in advance, the reference When the internal pressure exceeds the first threshold, the step of maintaining the sealed state of the bottle for a certain period of time, the step of measuring the amount of pressure drop from the reference internal pressure of the bottle internal pressure after the lapse of a certain time, and the measurement The pressure E Bei a step of rate reduction is checked whether within a second threshold value defined in advance, before SL and the pressure drop amount reference internal pressure exceeds the first threshold value exceeds the second threshold The bottle is determined to be a non-defective product without a pinhole only when there is no pinhole.
In the pinhole inspection method for a synthetic resin bottle, the bottle internal pressure immediately after sealing a predetermined amount of gas is set as a reference internal pressure, a threshold (first threshold) is set based on the reference internal pressure, and the first threshold is exceeded. Unfilled bottles are screened out as defective, and all subsequent steps such as pressure hold are not performed. On the other hand, when the bottle exceeds the first threshold, the pressure hold of the next process and the measurement of the pressure drop amount are sequentially performed, and the pressure drop amount does not exceed the second threshold value defined based on the temperature drop and the bottle deformation. The bottle is finally judged as a good product. As described above, by providing the second threshold value with respect to the reference internal pressure in the pressure drop measurement, it is possible to surely screen out defective product bottles having pinholes.

本発明の合成樹脂製ボトルのピンホール検査方法によれば、所定量のガスを密封した直後のボトル内圧を「圧力低下量計測の基準内圧」として、その基準内圧に対して第１閾値を設け、その第１閾値をクリアしたボトルに対して圧力ホールドと圧力低下量の計測を順に実施し、基準内圧からの圧力低下量が温度低下およびボトル変形に基づいて規定される第２閾値を超えていない場合はそのボトルは良品として判定される。これにより、ピンホールに起因してガス密封直後のボトル内圧が元々低く、その結果、圧力低下量が良品ボトルの圧力低下量に対し有意差を示さずに、従来の検査方法では良品と判定される虞のあったピンホールボトルを確実にふるい落とすことが出来るようになる。 According to the pinhole inspection method for a synthetic resin bottle of the present invention, a bottle internal pressure immediately after sealing a predetermined amount of gas is set as a “reference internal pressure for pressure drop measurement”, and a first threshold is provided for the reference internal pressure. The bottle that has cleared the first threshold is sequentially subjected to pressure hold and pressure drop measurement, and the pressure drop from the reference internal pressure exceeds the second threshold defined based on the temperature drop and bottle deformation. If not, the bottle is judged as good. As a result, the internal pressure of the bottle immediately after gas sealing due to the pinhole is originally low, and as a result, the pressure drop does not show a significant difference from the pressure drop of the non-defective bottle, and the conventional inspection method determines that the bottle is non-defective. It will be possible to reliably remove pinhole bottles.

以下、図に示す実施の形態により本発明をさらに詳細に説明する。   Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.

図１は、本発明に係るピンホール検査システム１００の要部を示す説明図である。
このピンホール検査システム１００は、ボトル１にエアを供給すると共にボトル内圧を出力するエア噴射機１０と、ボトル１の口部を把持しながらボトル１の姿勢を安定させるグリッパ２と、エア噴射機１０に対するエアの供給を断続する供給バルブ３と、ボトル１の一定時間経過後の基準内圧からの圧力低下量を計測する圧力検出部５と、一定圧に調圧されたエアを下流に安定供給するエア源６とを具備して構成されている。なお、詳細については後述するが、「ボトル１の基準内圧」とは、供給バルブ３を閉じた直後のボトル１の内圧である。また、圧力検出部５の詳細については図２を参照しながら後述する。 FIG. 1 is an explanatory view showing a main part of a pinhole inspection system 100 according to the present invention.
This pinhole inspection system 100 includes an air injector 10 that supplies air to the bottle 1 and outputs the bottle internal pressure, a gripper 2 that stabilizes the posture of the bottle 1 while gripping the mouth of the bottle 1, and an air injector A supply valve 3 for intermittently supplying air to the pressure 10, a pressure detecting unit 5 for measuring a pressure drop amount from a reference internal pressure after a predetermined time of the bottle 1, and a stable supply of air adjusted to a constant pressure downstream. And an air source 6 to be configured. Although details will be described later, the “reference internal pressure of the bottle 1” is an internal pressure of the bottle 1 immediately after the supply valve 3 is closed. Details of the pressure detection unit 5 will be described later with reference to FIG.

ボトル１は、ＰＥＴボトル等の合成樹脂製ボトルであり、プリフォームからブロー成形された後に、メインホイールの外周上に等間隔に配置されたグリッパ２によって首部を把持され正立状態でエア噴射機１０の真下に搬送されて来る。   The bottle 1 is a synthetic resin bottle such as a PET bottle. After being blow-molded from a preform, the bottle 1 is gripped by a gripper 2 arranged at equal intervals on the outer periphery of the main wheel, and the air jet is in an upright state. It is transported directly below 10.

供給バルブ３は、応答性の観点から電磁弁が好ましい。また、供給バルブ３は、バルブコントローラ（図示せず）によって所定のパルス駆動信号を印加され所定のＯＮ時間だけ開き、それ以外は閉状態を保つ、いわゆるノーマルクローズバルブである。   The supply valve 3 is preferably a solenoid valve from the viewpoint of responsiveness. The supply valve 3 is a so-called normally closed valve that is applied with a predetermined pulse drive signal by a valve controller (not shown) and opens for a predetermined ON time, and remains closed for the rest.

圧力検出部５は、ボトル１の内圧を計測する圧力センサと、一定時間経過後の基準内圧からの圧力低下量を計測する差圧センサとを備える。   The pressure detection unit 5 includes a pressure sensor that measures the internal pressure of the bottle 1 and a differential pressure sensor that measures the amount of pressure drop from the reference internal pressure after a predetermined time has elapsed.

エア源６は、調圧弁または減圧弁により例えば２１[kPa］に一定圧に調圧されたエアを下流に安定供給する。   The air source 6 stably supplies air, which has been adjusted to a constant pressure of, for example, 21 [kPa] by a pressure adjusting valve or a pressure reducing valve downstream.

エア噴射機１０は、ボトル口部にガスタイトに当接する加圧ヘッド１１と、内部にガス供給流路１２aと圧力検出流路１２bの２チャンネルの流路が形成されている本体１２と、ガスの導入口となる加圧ポート１３と、ボトル１の内圧を出力する圧力ポート１４と、加圧ヘッド１１がボトル口部に当接する際の衝撃を吸収するバネ機構１５とを具備して構成されている。   The air injector 10 includes a pressurizing head 11 that comes into contact with a gas tight at a bottle mouth portion, a main body 12 having a gas supply passage 12a and a pressure detection passage 12b formed therein, The pressure port 13 serving as the introduction port, the pressure port 14 that outputs the internal pressure of the bottle 1, and the spring mechanism 15 that absorbs an impact when the pressure head 11 comes into contact with the bottle mouth portion are configured. Yes.

エア噴射機１０（加圧ヘッド１１）は、昇降装置（図示せず）によって上下に移動することが可能である。従って、この昇降装置はボトル１にエアを供給する際は、加圧ヘッド１１を下降させボトル口部に当接させる一方、ボトル１からエアを排気する（エア密封状態を解除する）際は、加圧ヘッド１１を上昇させボトル口部から分離させる。また、加圧ヘッド１１は、ボトル口部との密封性（シール性）を確保するため、合成ゴム等の弾性体によって構成しても良い。また、エア噴射機１０には、バネ機構１５と共に或いはそれに代えて、加圧ヘッド１１の軸芯とボトル１の軸芯とのズレを補正するアライメント調節機構を具備させても良い。   The air injector 10 (pressure head 11) can be moved up and down by an elevating device (not shown). Therefore, when the air is supplied to the bottle 1, the lifting device lowers the pressure head 11 to contact the bottle mouth, while exhausting the air from the bottle 1 (releasing the air-sealed state) The pressure head 11 is raised and separated from the bottle mouth. Further, the pressurizing head 11 may be constituted by an elastic body such as a synthetic rubber in order to secure a sealing property (sealing property) with the bottle mouth portion. Further, the air injector 10 may be provided with an alignment adjusting mechanism that corrects a deviation between the axis of the pressure head 11 and the axis of the bottle 1 together with or instead of the spring mechanism 15.

図２は、圧力検出部５の要部を示す説明図である。
この圧力検出部５は、ボトル１の内圧を常時計測する圧力センサ５１と、ボトル１の一定時間経過後の基準内圧からの圧力低下量を計測する差圧センサ５２と、差圧センサ５２の２つのチャンバを連通／非連通状態にする差圧バルブ５３とから成る。また、後述するように、差圧バルブ５３の開閉の動作は、供給バルブ３の開閉動作に同期しており、供給バルブ３が開(ON)の時は差圧バルブ５３も同時に開(ON)となり、供給バルブ３が閉(OFF)の時は差圧バルブ５３も同時に閉(OFF)となる。 FIG. 2 is an explanatory diagram showing a main part of the pressure detection unit 5.
The pressure detection unit 5 includes a pressure sensor 51 that constantly measures the internal pressure of the bottle 1, a differential pressure sensor 52 that measures a pressure drop amount from a reference internal pressure after the bottle 1 has elapsed for a fixed time, and a differential pressure sensor 52. And a differential pressure valve 53 for bringing the two chambers into communication / non-communication. As will be described later, the opening / closing operation of the differential pressure valve 53 is synchronized with the opening / closing operation of the supply valve 3. When the supply valve 3 is open (ON), the differential pressure valve 53 is simultaneously opened (ON). Thus, when the supply valve 3 is closed (OFF), the differential pressure valve 53 is simultaneously closed (OFF).

差圧センサ５２は、常時ボトル１に連通した第１チャンバ５２aと、差圧バルブ５３がＯＮの時のみボトル１に連通する第２チャンバ５２bという２つのチャンバを有する。従って第１チャンバ５２aの圧力は、ボトル１の内圧を常時モニタしている。また、第２チャンバ５２bは、差圧バルブ５３がＯＦＦ（供給バルブ３がＯＦＦ）となる時に、ボトル１および第２チャンバ５２bと非連通状態となるため、差圧バルブ５３がＯＦＦの間の第２チャンバ５２bの圧力は、供給バルブ３がＯＦＦとなった直後のボトル１の内圧を示していることになる。従って、この第２チャンバ５２bの圧力は、ボトル１の一定時間経過後の圧力低下量を計測する際の基準内圧となる。従って、差圧センサ５２は、（供給バルブ３がＯＦＦとなった直後のボトル１の内圧）−（リアルタイムのボトル１の内圧）＝時間経過後のボトル１の圧力低下量をモニタしていることになる。   The differential pressure sensor 52 has two chambers: a first chamber 52a that always communicates with the bottle 1 and a second chamber 52b that communicates with the bottle 1 only when the differential pressure valve 53 is ON. Therefore, the pressure in the first chamber 52a constantly monitors the internal pressure of the bottle 1. The second chamber 52b is not in communication with the bottle 1 and the second chamber 52b when the differential pressure valve 53 is OFF (the supply valve 3 is OFF). The pressure in the two chamber 52b indicates the internal pressure of the bottle 1 immediately after the supply valve 3 is turned off. Therefore, the pressure in the second chamber 52b becomes the reference internal pressure when measuring the amount of pressure drop after a fixed time has elapsed in the bottle 1. Therefore, the differential pressure sensor 52 is monitoring (the internal pressure of the bottle 1 immediately after the supply valve 3 is turned off) − (the internal pressure of the bottle 1 in real time) = the pressure drop amount of the bottle 1 after a lapse of time. become.

図３から５は、圧力検出部５の動作を示す説明図である。
先ず、図３に示すように、供給バルブ３を開(ON)とすると、同時に差圧バルブ５３も開(ON)となり、ボトル１、差圧センサ５２の第１チャンバ５３ａおよび第２チャンバ５３ｂに対しエアが供給される。このエア導入直後のボトル内部は、エアの分子同士が激しく衝突する過度状態にあり、そのためエアの温度は上昇する。しかし、時間の経過と共にボトル内部は定常状態に近づき、なお且つボトルの胴部が外方に膨らみ、その結果、ボトル１の内圧は徐々に低下し一定圧に収束する。 3 to 5 are explanatory diagrams showing the operation of the pressure detection unit 5.
First, as shown in FIG. 3, when the supply valve 3 is opened (ON), the differential pressure valve 53 is also opened (ON), and the bottle 1 and the first chamber 53a and the second chamber 53b of the differential pressure sensor 52 are opened. On the other hand, air is supplied. The inside of the bottle immediately after the introduction of air is in an excessive state in which air molecules collide violently, so that the temperature of the air rises. However, with the passage of time, the inside of the bottle approaches a steady state, and the body of the bottle swells outward. As a result, the internal pressure of the bottle 1 gradually decreases and converges to a constant pressure.

図４に示すように、供給バルブ３の一定ＯＮ時間の後、すなわち所定量のエアが供給された後は、供給バルブ３と差圧バルブ５３はＯＦＦとなり、第１チャンバ５２aと第２チャンバ５２bは非連通状態になる。この時の圧力センサ５１の指示値は圧力低下量計測の基準内圧となり、基準内圧が閾値を超えているか否かを検査する工程において使用される。また、この時、第１チャンバ５２aの圧力と第２チャンバ５２bの圧力は互いに等しく、その結果、差圧センサ５２はゼロを指示している。   As shown in FIG. 4, after a certain ON time of the supply valve 3, that is, after a predetermined amount of air is supplied, the supply valve 3 and the differential pressure valve 53 are turned OFF, and the first chamber 52a and the second chamber 52b. Will be out of communication. The indicated value of the pressure sensor 51 at this time becomes a reference internal pressure for measuring the amount of pressure drop, and is used in a process of checking whether the reference internal pressure exceeds a threshold value. At this time, the pressure in the first chamber 52a and the pressure in the second chamber 52b are equal to each other, and as a result, the differential pressure sensor 52 indicates zero.

図５に示すように、一定時間経過後、ボトル１の内部は定常状態になる。もし、ボトル１にピンホール等のボトルの気密性を阻害する欠陥等がなければ、主として温度低下とボトル変形に起因する若干の圧力低下が発生するのみである。しかし、もしボトル１にピンホール等があれば、それ以上の圧力低下が発生し、その結果、差圧センサ５２の第１チャンバ５２aと第２チャンバ５２bとの間に、これらの圧力低下に対応した圧力差が発生する。   As shown in FIG. 5, the inside of the bottle 1 is in a steady state after a certain time has elapsed. If the bottle 1 has no defects such as pinholes that hinder the airtightness of the bottle, only a slight pressure drop mainly due to temperature drop and bottle deformation occurs. However, if there is a pinhole or the like in the bottle 1, a further pressure drop occurs, and as a result, the pressure drop between the first chamber 52a and the second chamber 52b of the differential pressure sensor 52 corresponds to these pressure drops. Pressure difference occurs.

図６は、本発明のピンホール検査方法における良品ボトルを判定する一例を示すグラフである。   FIG. 6 is a graph showing an example of determining a non-defective bottle in the pinhole inspection method of the present invention.

時刻Ｔ＝t0に供給バルブ３を開とすると、ボトルの内部にエアが供給され、ボトルの内圧が急激に立ち上がる。これは、ちょうど図３の状態に相当する。
そして、ボトル１に所定量のエアが供給されると、時刻Ｔ＝t1に供給バルブ３を閉とする。これは、ちょうど図４の状態に相当する。ここで、供給バルブ３を閉とした直後のボトル内圧Ｐ1（基準内圧）が、第１閾値Pth1を超えているか否かをチェックする。ボトル内圧Ｐ1が、第１閾値Pth1を超えている場合は、ボトル１を一定時間ホールドし、基準内圧からの圧力低下量ΔPを計測する。 When the supply valve 3 is opened at time T = t 0 , air is supplied into the bottle and the internal pressure of the bottle rises rapidly. This corresponds to the state of FIG.
When the bottle 1 is a predetermined amount of air is supplied, the supply valve 3 is closed at time T = t 1. This corresponds to the state of FIG. Here, it is checked whether or not the bottle internal pressure P 1 (reference internal pressure) immediately after the supply valve 3 is closed exceeds the first threshold value P th1 . When the bottle internal pressure P 1 exceeds the first threshold value P th1 , the bottle 1 is held for a certain time, and the pressure drop amount ΔP from the reference internal pressure is measured.

圧力低下量ΔPは、基準内圧Ｐ1と、一定時間経過後、すなわち加圧ヘッド１１をボトル口部から分離する直前のボトル内圧Ｐ2との圧力差ΔP＝Ｐ1−Ｐ2から求められる。しかし、各圧力値Ｐ1,Ｐ2は別個に求めることはせずに、圧力低下量ΔPは差圧センサ５２によって計測される。そして、計測した圧力低下量ΔPが第２閾値ΔPth2を超えていない場合は、そのボトルは良品と判定する。 The pressure drop amount ΔP is obtained from the pressure difference ΔP = P 1 −P 2 between the reference internal pressure P 1 and the bottle internal pressure P 2 immediately after the elapse of a fixed time, that is, immediately before the pressure head 11 is separated from the bottle mouth. However, the pressure drop amount ΔP is measured by the differential pressure sensor 52 without obtaining the pressure values P 1 and P 2 separately. When the measured pressure drop amount ΔP does not exceed the second threshold value ΔP th2 , the bottle is determined to be a non-defective product.

そして、時刻Ｔ＝t2に加圧ヘッド１１をボトル口部から分離し、そしてボトル１のエアを排気しピンホール検査を終了する。 At time T = t 2 , the pressure head 11 is separated from the bottle mouth, and the air in the bottle 1 is exhausted to finish the pinhole inspection.

このように、先ず基準内圧Ｐ1が第１閾値Ｐth1を超えているか否かを検査する。超えている場合は、次の圧力低下量の検査へ移行し、供給バルブ３を閉じた直後からの圧力低下量ΔPが第２閾値ΔPth2を超えているか否かを検査する。そして、圧力低下量ΔPが第２閾値ΔPth2の範囲内に収まっている場合にのみ、ボトルはピンホールがない良品と判定する。第１閾値Ｐth1としては、例えば８[kPa]である。また、第２閾値ΔPth2としては、例えば３[kPa]である。また、基準圧力Ｐ1としては、例えば１５〜２０[kPa]である。 Thus, first, it is checked whether or not the reference internal pressure P 1 exceeds the first threshold value P th1 . If it exceeds, the process proceeds to the next pressure drop amount inspection, and it is checked whether or not the pressure drop amount ΔP immediately after closing the supply valve 3 exceeds the second threshold value ΔP th2 . Only when the pressure drop amount ΔP is within the range of the second threshold value ΔP th2 , the bottle is determined to be a non-defective product having no pinhole. The first threshold value P th1 is, for example, 8 [kPa]. The second threshold value ΔP th2 is 3 [kPa], for example. The reference pressure P 1 is, for example, 15 to 20 [kPa].

図７は、本発明のピンホール検査方法における不良品ボトルを判定する一例を示すグラフである。
このボトルは、基準内圧Ｐ1が第１閾値Ｐth1を超えているが、圧力低下量ΔPが第２閾値ΔPth2を超えている。従って、このボトルにはピンホールが存在するものと考えられ、このボトルは不良品と判定される。 FIG. 7 is a graph showing an example of determining a defective bottle in the pinhole inspection method of the present invention.
In this bottle, the reference internal pressure P 1 exceeds the first threshold value P th1 , but the pressure drop amount ΔP exceeds the second threshold value ΔP th2 . Therefore, it is considered that this bottle has a pinhole, and this bottle is determined to be defective.

図８は、本発明のピンホール検査方法における不良品ボトルを判定する一例を示すグラフである。
このボトルは、基準内圧Ｐ1が第１閾値Ｐth1をクリアしていない。従って、このボトルはピンホールが存在するものと考えられ不良品と判定される。また、圧力ホールド及び圧力低下量ΔPは計測されずに、暫くして加圧ヘッド１１をボトル口部から分離してピンホール検査は終了となる。 FIG. 8 is a graph showing an example of determining a defective bottle in the pinhole inspection method of the present invention.
In this bottle, the reference internal pressure P 1 does not clear the first threshold value P th1 . Therefore, this bottle is considered to have a pinhole and is determined to be defective. Further, the pressure hold and the pressure drop amount ΔP are not measured, and the pressure head 11 is separated from the bottle mouth portion for a while, and the pinhole inspection is completed.

本発明のピンホール検査方法によれば、エア密封直後のボトル内圧に相当する基準内圧Ｐ1に対しても第１閾値Ｐth1を設け、その基準内圧Ｐ1が第１閾値Ｐth1を超えない場合は、圧力低下量ΔPを計測せずにそのボトルは不良品と判定される。また、その基準内圧Ｐ1が第１閾値Ｐth1を超える場合であっても、圧力低下量ΔPが第２閾値Δth2を超える場合はそのボトルは不良品として判定されることになる。つまり、供給バルブ３を閉じた直後のボトル１の基準内圧Ｐ1が第１閾値Ｐth1を超えて、なお且つその基準内圧Ｐ1からの圧力低下量ΔPが第２閾値ΔPth2を超えない場合に限りそのボトルは良品と判定される。従って、圧力低下量ΔPのみでピンホールの有無を判定していた従来のピンホール検査方法では、看過されていたピンホールボトルを確実にふるい落とすことができ、ピンホール検査精度が向上する。 According to the pinhole inspection method of the present invention, the first threshold value P th1 is provided even for the reference internal pressure P 1 corresponding to the bottle internal pressure immediately after air sealing, and the reference internal pressure P 1 does not exceed the first threshold value P th1 . In this case, the bottle is determined to be defective without measuring the pressure drop amount ΔP. Even if the reference internal pressure P 1 exceeds the first threshold value P th1 , if the pressure drop amount ΔP exceeds the second threshold value Δ th2 , the bottle is determined as a defective product. That is, when the reference internal pressure P 1 of the bottle 1 immediately after closing the supply valve 3 exceeds the first threshold P th1 and the pressure drop amount ΔP from the reference internal pressure P 1 does not exceed the second threshold ΔP th2. As long as the bottle is determined to be non-defective. Therefore, in the conventional pinhole inspection method in which the presence or absence of the pinhole is determined only by the pressure drop amount ΔP, the overlooked pinhole bottle can be surely removed, and the pinhole inspection accuracy is improved.

なお、上記実施例においては、ボトルピンホール検査用ガスとしてエアが使用されているが、これに限らずヘリウムおよび窒素等の不活性ガス又はこれらとエアとの混合ガスを使用しても良い。   In the above embodiment, air is used as the bottle pinhole inspection gas. However, the present invention is not limited to this, and an inert gas such as helium and nitrogen or a mixed gas of these and air may be used.

本発明のピンホール検査方法は、ガスを容器に密封し一定時間経過後の容器内圧の低下量を計測することにより容器のピンホールの有無を判定する容器のピンホール検査方法に好適に適用することが出来る。   The pinhole inspection method of the present invention is suitably applied to a container pinhole inspection method for determining the presence or absence of a pinhole in a container by sealing the gas in the container and measuring the amount of decrease in the container internal pressure after a lapse of a certain time. I can do it.

本発明に係るピンホール検査システムの要部を示す説明図である。It is explanatory drawing which shows the principal part of the pinhole inspection system which concerns on this invention. 圧力検出部の要部を示す説明図である。It is explanatory drawing which shows the principal part of a pressure detection part. 供給バルブが開となった直後の圧力検出部の動作を示す説明図である。It is explanatory drawing which shows operation | movement of the pressure detection part immediately after a supply valve is opened. 供給バルブが閉となった直後の圧力検出部の動作を示す説明図である。It is explanatory drawing which shows operation | movement of the pressure detection part immediately after a supply valve becomes closed. 加圧ヘッド１１がボトル口部から分離する直前の圧力検出部の動作を示す説明図である。It is explanatory drawing which shows operation | movement of the pressure detection part just before the pressurization head 11 isolate | separates from a bottle mouth part. 本発明のピンホール検査方法における良品ボトルを判定する一例を示すグラフである。It is a graph which shows an example which determines the non-defective bottle in the pinhole inspection method of the present invention. 本発明のピンホール検査方法における不良品ボトルを判定する一例を示すグラフである。It is a graph which shows an example which determines the inferior goods bottle in the pinhole inspection method of this invention. 本発明のピンホール検査方法における不良品ボトルを判定する一例を示すグラフである。It is a graph which shows an example which determines the inferior goods bottle in the pinhole inspection method of this invention. 従来の圧力低下量からピンホールの有無を判定するピンホール検査方法を示すグラフである。It is a graph which shows the pinhole test | inspection method which determines the presence or absence of a pinhole from the conventional pressure drop amount.

符号の説明Explanation of symbols

１ ボトル
２ グリッパ
３ 供給バルブ
５ 圧力検出部
６ エア源
１０ エア噴射機
１１ 加圧ヘッド
１２ 本体
１３ 供給ポート
１４ 圧力ポート
１５ バネ機構
１００ ピンホール検査システム DESCRIPTION OF SYMBOLS 1 Bottle 2 Gripper 3 Supply valve 5 Pressure detection part 6 Air source 10 Air injector 11 Pressurization head 12 Main body 13 Supply port 14 Pressure port 15 Spring mechanism 100 Pinhole inspection system

Claims (1)

ブロー成形された合成樹脂製ボトルにガスを注入し、ボトルの内の圧力を計測して閾値と比較することでピンホールの有無を判定する合成樹脂製ボトルのピンホール検査方法であって、
前記閾値が、注入されるガスの圧力に基づいて規定される第１閾値と、温度低下およびボトル変形に基づいて規定される第２閾値からなり、
前記ボトルにガスを密封する工程と、密封直後の該ボトル内圧を基準内圧として計測し、該基準内圧が予め規定した第１閾値を超えているか否かをチェックする工程と、該基準内圧が該第１閾値を超えている場合は、該ボトルの密封状態を一定時間保持する工程と、一定時間経過後の該ボトル内圧の前記基準内圧からの圧力低下量を計測する工程と、計測した該圧力低下量が予め規定した第２閾値以内であるか否かをチェックする工程とを備え、
前記基準内圧が前記第１閾値を超えており且つ前記圧力低下量が前記第２閾値を超えていない場合に限り、前記ボトルはピンホールのない良品と判定することを特徴とする合成樹脂製ボトルのピンホール検査方法。 Injecting gas into a blown synthetic resin bottle, measuring the pressure in the bottle and comparing it with a threshold value to determine the presence or absence of a pinhole, it is a pinhole inspection method for a synthetic resin bottle,
The threshold value includes a first threshold value defined based on the pressure of the injected gas, and a second threshold value defined based on the temperature drop and bottle deformation.
A step of sealing gas into the bottle, the bottle inner pressure immediately after sealing is measured as a reference inner pressure, a step of checking whether the reference inner pressure exceeds the first threshold value defined in advance, the reference internal pressure is the If the first threshold value is exceeded, the step of maintaining the sealed state of the bottle for a certain period of time, the step of measuring the amount of pressure decrease from the reference internal pressure of the bottle internal pressure after the lapse of the certain time, and the measured pressure e Bei a step of rate reduction is checked whether within a second threshold value defined in advance,
A synthetic resin bottle characterized in that the bottle is determined to be a non-defective product without a pinhole only when the reference internal pressure exceeds the first threshold and the pressure drop does not exceed the second threshold. Pinhole inspection method.
JP2007279983A 2007-10-29 2007-10-29 Pinhole inspection method for plastic bottles Active JP5067550B2 (en)

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Application Number Priority Date Filing Date Title
JP2007279983A JP5067550B2 (en) 2007-10-29 2007-10-29 Pinhole inspection method for plastic bottles
KR20107008271A KR101485888B1 (en) 2007-10-29 2008-10-29 Method and apparatus for inspecting pinhole in synthetic resin bottle
CN200880113734.3A CN101842682B (en) 2007-10-29 2008-10-29 Method and apparatus for inspecting pinhole in synthetic resin bottle
PCT/JP2008/069646 WO2009057636A1 (en) 2007-10-29 2008-10-29 Method and apparatus for inspecting pinhole in synthetic resin bottle
US12/739,581 US8713993B2 (en) 2007-10-29 2008-10-29 Method and apparatus for inspecting pinhole in synthetic resin bottle
EP08845905.2A EP2213997B1 (en) 2007-10-29 2008-10-29 Method and apparatus for inspecting pinhole in synthetic resin bottle

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JP5067550B2 true JP5067550B2 (en) 2012-11-07

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