JP3549098B2

JP3549098B2 - Injection device check valve

Info

Publication number: JP3549098B2
Application number: JP2000134646A
Authority: JP
Inventors: 伸之中村
Original assignee: Nissei Plastic Industrial Co Ltd
Current assignee: Nissei Plastic Industrial Co Ltd
Priority date: 2000-05-08
Filing date: 2000-05-08
Publication date: 2004-08-04
Anticipated expiration: 2020-05-08
Also published as: JP2001315175A

Description

【０００１】
【発明の属する技術分野】
本発明は逆流防止弁の洩れ量減少技術に関する。
【０００２】
【従来の技術】
図６（ａ），（ｂ）は従来の逆流防止弁の構造図兼作用図である。
（ａ）において、射出装置の逆流防止弁１００は、スクリューヘッド１０１と、このスクリューヘッド１０１に嵌めた円筒形状のチェックリング１０２とからなり、加熱筒１０３に挿入したスクリュー１０４の先端に設けたものである。
計量工程では、スクリュー１０４を廻すことにより、矢印▲１▼，▲１▼及び矢印▲２▼，▲２▼の通りに、チェックリング１０２とスクリューヘッド１０１との間で形成した流路１０５を通じて樹脂を通過させる。
【０００３】
（ｂ）は射出工程を示し、射出時にはスクリュー１０４を矢印▲３▼の通りに前進させる。この前進に伴なってスクリューヘッド１０１の前に溜まっている樹脂１０６の圧力がチェックリング１０２に矢印▲４▼，▲４▼のごとく作用し、結果としてチェックリング１０２が後退し、スクリュー１０４のシート１０７に当り、樹脂の逆流（スクリュー１０４への流れ）を防止することができる。
【０００４】
【発明が解決しようとする課題】
図６（ａ）から（ｂ）に至るまで、すなわち、（ａ）に示すストロークＳ１がゼロになるまでに、微量ではあるが樹脂は逆流する。逆流した分は、射出されないので実質射出量は減少する。同時に計量精度の低下を招く。
射出速度の高速化や計量精度の向上を図る上では、逆流樹脂量の減少が不可欠である。
そこで、本発明の目的は逆流防止弁における樹脂の逆流を減少させることのできる技術を提供することにある。
【０００５】
【課題を解決するための手段】
上記目的を達成するために請求項１は、スクリューヘッドにチェックリングを嵌め、このチェックリングを前進させることで弁開状態、後退させることで弁閉状態にすることができ、樹脂の計量工程では弁開状態にしたチェックリングとスクリューヘッドとの間で形成した流路を通じて樹脂を通過させることができる射出装置の逆流防止弁において、流路をスクリューヘッドの先端側からスクリューに向って、第１流路部、第２流路部及び第３流路部に区分し、第２流路部の断面積を前後の第１・第３流路部より大きく設定すると共に、第２流路部の長さを第１・第３流路部より長く設定することで、第２流路部の容積を前後の第１・第３流路部の容積より十分に大きく設定し、且つ前記第１流路部の容積を、第３流路部の容積より小さく設定したことを特徴とする。
【０００６】
第１流路部の断面積を小さくすることにより、射出時に発生する樹脂の逆流を抑制する。第２流路部の断面積を大きくすることにより逆流樹脂の流速を下げる。且つ第２流路部の長さを大きくすることで、逆流樹脂が第３流路部に到達するまでの時間を稼ぐ。すなわち、第２流路部の容積を大きくしたことで圧縮に伴なって圧力が上昇するところの圧縮昇圧を遅らせることができる。第３流路部の断面積を小さくすることにより、樹脂の逆流を抑制する。以上の第１〜第３流路部の作用を総合することにより、迅速にチェックリングを後退させること、すなわち逆流防止弁を閉じることができ、樹脂の逆流を大幅に減少させることができる。
そして、第１流路部の容積を、第３流路部の容積より小さく設定したので、逆流防止弁をより迅速に閉じことができる。
【０００７】
請求項２では、チェックリングの前進、後退に伴う移動代を、チェックリングのストロークと呼ぶときに、第３流路部の断面積と同一になるように前記ストロークを定めたことを特徴とする。
ストロークを十分に小さくすることができ、逆流防止弁の締切りに要する時間を大幅に短くすることができる。
【０００８】
【発明の実施の形態】
本発明の実施の形態を添付図に基づいて以下に説明する。
図１は本発明に係る射出装置の逆流防止弁（第１実施例）の断面図であり、逆流防止弁１０は、スクリューヘッド１１と、このスクリューヘッド１１に嵌めた円筒形状のチェックリング１２とからなり、加熱筒１３に挿入したスクリュー１４の先端に設け、樹脂の計量工程ではチェックリング１２とスクリューヘッド１１との間で形成した流路２０を通じて樹脂を通過させることができる弁であり、流路２０をスクリューヘッド１１の先端側からスクリュー１４に向って、第１流路部２１、第２流路部２２及び第３流路部２３に区分し、第２流路部２２の断面積Ａ２を第１流路部２１の断面積Ａ１より大きく且つ第３流路部２３の断面積Ａ３より大きく設定すると共に、第２流路部の長さＬ２を第１・第３流路部２１，２３の長さＬ１，Ｌ３より大きく設定することで、第２流路部２２の容積Ｖ２を前後の第１・第３流路部２１，２３の容積Ｖ１，Ｖ３より十分に大きく設定したことを特徴とする。
【０００９】
更に、第１流路部２１の隙間をδ１、長さをＬ１とし、第３流路部２３の隙間をδ３、長さをＬ３とするときに、δ１＜δ３且つＬ１＞Ｌ３の関係に保ちつつ、第１流路部２１の容積Ｖ１を、第３流路部２３の容積Ｖ３より小さく設定する。
【００１０】
隙間δ１が小さければ流路抵抗が大きくなり、長さＬ１が大きければ流路抵抗が大きくなる。従って、第１流路部２１で効果的に樹脂の逆流を抑えることができる。
加えて、第１・第３流路部２１，２３は外径が同じであるから、内径に差がつく。結果的に、チェックリング１２の前面２４の面積が十分に大きくなる。
【００１１】
そして、この第１実施例ではチェックリング１２は、円筒材料の内面を研削することで、第２流路部２２及び第３流路部２３の壁を形成する。この削り込みにより、第３流路部２３の断面積Ａ３を決定し、この断面積Ａ３とほぼ同一の開口面積となるように、シート２５とチェックリング１２とのストロークＳ２を決定する。この決定方法によればストロークＳ２は十分に小さくすることができる（図６（ａ）を比較参照）。
【００１２】
そして矢印で示す如く、計量工程において、ストロークＳ２の開口、第３流路部２３、第２流路部２２、第１流路部２１の順で樹脂をスクリューヘッド１１の前へ送ることができる。
【００１３】
図２は本発明に係る逆流防止弁の射出初期の作用説明図であり、スクリュー１４を前進させることにより、相対的に樹脂圧力がチェックリングの前面２４に作用すると共に、樹脂の一部が第１流路部２１へ侵入し、次に第２流路部２２へ侵入する。
このときに、第１流路部２１の容積Ｖ１は十分に小さくて絞り部の作用を発揮するため、第１流路部２１へ侵入する樹脂の量は少なくなる。
【００１４】
この少ない量の樹脂が第１流路部２１から第２流路部２２へ流入するときには、第２流路部２２の断面積Ａ２が十分に大きいため、樹脂の流速は低下する。そして、第２流路部２２の長さが十分に大きいため、第２流路部２２の樹脂が第３流路部２３に到達するには時間が掛る。この結果、逆流樹脂は従来より格段に遅れてストロークＳ２の開口に到達することになる。
【００１５】
逆流樹脂がストロークＳ２の開口に到達すると、到達した樹脂がチェックリング１２の背面を矢印▲５▼のように押し、この結果、チェックリング１２の閉じ速度が低下し、締切が遅れ、逆流する樹脂量が増加することが考えられる。
しかし、本発明では第１流路部２１で絞り作用にて逆流樹脂の流れに抵抗を持たせ、第２流路部２２で減速し、第３流路部２３で再度逆流樹脂の流れに抵抗を持たせことで、逆流樹脂の到達を大幅に遅らせることができる。
加えて、チェックリング１２の前面２４の面積を十分に大きくしたので、樹脂圧力による弁閉力は従来より大きくなる。
弁閉力が大きく且つ樹脂の廻り込みが遅れるため、実質的には逆流樹脂がストロークＳ２の開口に到達する前に弁閉状態にすることができる。
【００１６】
なお、第１流路部２１、第２流路部２２及び第３流路部２３の寸法決定に当っては、流路２０におけるトータルの圧力損失を１００％としたとき、第１流路部２１に５０〜６０％を割り当て、第３流路部２３に２５〜３５％を割り当て、残りの５〜２５％を第２流路部２２に割り当てるとよい。
【００１７】
図３は本発明に係る逆流防止弁の弁閉状態説明図であり、チェックリング１２がシート２５に接して弁閉状態になったことを示す。この弁閉状態は従来より短い時間に完了するため、逆流樹脂はゼロ若しくは発生したとしても微量になる。
この結果、射出速度の高速化や計量精度の向上を図ることができる。
【００１８】
図４は本発明に係る射出装置の逆流防止弁（第２実施例）の断面図であり、この逆流防止弁１０Ｂも、スクリューヘッド１１と、このスクリューヘッド１１に嵌めた円筒形状のチェックリング１２とからなり、計量工程ではチェックリング１２とスクリューヘッド１１との間で形成した流路２０を通じて樹脂を通過させることができる弁であり、流路２０をスクリューヘッド１１の先端側からスクリュー１４に向って、第１流路部２１、第２流路部２２及び第３流路部２３に区分し、第２流路部２２の断面積Ａ２を第１流路部２１の断面積Ａ１より大きく且つ第３流路部２３の断面積Ａ３より大きく設定すると共に、第２流路部の長さＬ２を第１・第３流路部２１，２３の長さＬ１，Ｌ３より大きく設定することで、第２流路部２２の容積Ｖ２を前後の第１・第３流路部２１，２３の容積Ｖ１，Ｖ３より十分に大きく設定したことを特徴とする。
【００１９】
更に、第１流路部２１の隙間をδ１、長さをＬ１とし、第３流路部２３の隙間をδ３、長さをＬ３とするときに、δ１＜δ３且つＬ１＞Ｌ３の関係に保ちつつ、第１流路部２１の容積Ｖ１を、第３流路部２３の容積Ｖ３より小さく設定する。
【００２０】
隙間δ１が小さければ流路抵抗が大きくなり、長さＬ１が大きければ流路抵抗が大きくなる。従って、第１流路部２１で効果的に樹脂の逆流を抑えることができる。
【００２１】
具体的には、この第２実施例ではチェックリング１２は円筒形状のままとし、スクリューヘッド１１を研削することで、第２流路部２２を形成する。
第１流路部２１で逆流樹脂の流れに抵抗を持たせ、第２流路部２２で減速し、第３流路部２３で再度逆流樹脂の流れに抵抗を持たせことで、逆流樹脂の到達を大幅に遅らせることができる。
加えて、チェックリング１２の前面２４の面積を十分に大きくしたので、樹脂による弁閉力は従来より大きくなる。
弁閉力が大きく且つ樹脂の廻り込みが遅れるため、実質的には逆流樹脂がストロークＳ２の開口に到達する前に弁閉状態にすることができる。
【００２２】
図５は本発明に係る射出装置の逆流防止弁（第３実施例）の断面図であり、この逆流防止弁１０Ｃも、スクリューヘッド１１と、このスクリューヘッド１１に嵌めた円筒形状のチェックリング１２とからなり、計量工程ではチェックリング１２とスクリューヘッド１１との間で形成した流路２０を通じて樹脂を通過させることができる弁であり、流路２０をスクリューヘッド１１の先端側からスクリュー１４に向って、第１流路部２１、第２流路部２２及び第３流路部２３に区分し、第２流路部２２の断面積Ａ２を第１流路部２１の断面積Ａ１より大きく且つ第３流路部２３の断面積Ａ３より大きく設定すると共に、第２流路部の長さＬ２を第１・第３流路部２１，２３の長さＬ１，Ｌ３より大きく設定することで、第２流路部２２の容積Ｖ２を前後の第１・第３流路部２１，２３の容積Ｖ１，Ｖ３より十分に大きく設定したことを特徴とする。
【００２３】
更に、第１流路部２１の隙間をδ１、長さをＬ１とし、第３流路部２３の隙間をδ３、長さをＬ３とするときに、δ１＜δ３且つＬ１＞Ｌ３の関係に保ちつつ、第１流路部２１の容積Ｖ１を、第３流路部２３の容積Ｖ３より小さく設定する。
【００２４】
隙間δ１が小さければ流路抵抗が大きくなり、長さＬ１が大きければ流路抵抗が大きくなる。従って、第１流路部２１で効果的に樹脂の逆流を抑えることができる。
【００２５】
具体的には、この第３実施例ではチェックリング１２は、円筒材料の内面をＵ溝状に研削することで、第２流路部２２を形成する。
第１流路部２１で逆流樹脂の流れに抵抗を持たせ、第２流路部２２で減速し、第３流路部２３で再度逆流樹脂の流れに抵抗を持たせことで、逆流樹脂の到達を大幅に遅らせることができる。
加えて、チェックリング１２の前面２４の面積を十分に大きくしたので、樹脂による弁閉力は従来より大きくなる。
弁閉力が大きく且つ樹脂の廻り込みが遅れるため、実質的には逆流樹脂がストロークＳ２の開口に到達する前に弁閉状態にすることができる。
【００２６】
尚、請求項１においては、第３流路部の容積は第１流路の容積と同じであっても差支えない。要は、第２流路部の容積を前後の第１・第３流路部の容積より十分に大きく設定すればよいからである。
【００２７】
【発明の効果】
本発明は上記構成により次の効果を発揮する。
請求項１では、第１流路部の断面積を小さくすることにより、射出時に発生する樹脂の逆流を抑制し、第２流路部の断面積を大きくすることにより逆流樹脂の流速を下げ、且つ第２流路部の長さを大きくすることで逆流樹脂が第３流路部に到達するまでの時間を稼ぐ。すなわち、第２流路部の容積を大きくしたことで圧縮に伴なって圧力が上昇するところの圧縮昇圧を遅らせることができる。第３流路部の断面積を小さくすることにより、樹脂の逆流を抑制する。以上の第１〜第３流路部の作用を総合することにより、迅速にチェックリングを後退させること、すなわち逆流防止弁を閉じることができ、樹脂の逆流を大幅に減少させることができる。逆流防止弁を迅速に閉じることができるので、射出速度の高速化や計量精度の向上を図ることができる。
加えて、第１流路部の容積を、第３流路部の容積より小さく設定したことを特徴とし、第１流路部を絞ることで、逆流防止弁をより迅速に閉じことができる。従って、射出速度のさらなる高速化や計量精度のさらなる向上を図ることができる。
【００２８】
請求項２では、チェックリングの前進、後退に伴う移動代を、チェックリングのストロークと呼ぶときに、第３流路部の断面積と同一になるようにストロークを定めたので、ストロークを十分に小さくすることができ、逆流防止弁の締切りに要する時間を大幅に短くすることができる。
【図面の簡単な説明】
【図１】本発明に係る射出装置の逆流防止弁（第１実施例）の断面図
【図２】本発明に係る逆流防止弁の射出初期の作用説明図
【図３】本発明に係る逆流防止弁の弁閉状態説明図
【図４】本発明に係る射出装置の逆流防止弁（第２実施例）の断面図
【図５】本発明に係る射出装置の逆流防止弁（第３実施例）の断面図
【図６】従来の逆流防止弁の構造図兼作用図
【符号の説明】
１０，１０Ｂ，１０Ｃ…逆流防止弁、１１…スクリューヘッド、１２…チェックリング、１３…加熱筒、１４…スクリュー、２０…流路、２１…第１流路部、２２…第２流路部、２３…第３流路部、２４…チェックリングの前面、２５…シート、Ａ１〜Ａ３…流路部の断面積、Ｌ１〜Ｌ３…流路部の長さ、Ｖ１〜Ｖ３…流路部の容積、δ１，δ３…流路部の隙間。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for reducing the amount of leakage of a check valve.
[0002]
[Prior art]
FIGS. 6 (a) and 6 (b) are structural views and action diagrams of a conventional check valve.
1A, a check valve 100 of an injection device includes a screw head 101 and a cylindrical check ring 102 fitted on the screw head 101, and is provided at the tip of a screw 104 inserted into a heating cylinder 103. It is.
In the measuring step, by turning the screw 104, the resin is passed through the flow path 105 formed between the check ring 102 and the screw head 101 as shown by arrows (1) and (1) and arrows (2) and (2). Through.
[0003]
(B) shows an injection step, in which the screw 104 is advanced in the direction of arrow (3) during injection. With this advance, the pressure of the resin 106 accumulated in front of the screw head 101 acts on the check ring 102 as shown by arrows {circle around (4)} and {circle around (4)}. At 107, the backflow of the resin (flow to the screw 104) can be prevented.
[0004]
[Problems to be solved by the invention]
A small amount of resin flows backward from FIG. 6A to FIG. 6B, that is, until the stroke S1 shown in FIG. 6A becomes zero. Since the backflow is not injected, the actual injection amount decreases. At the same time, the weighing accuracy is reduced.
In order to increase the injection speed and improve the measurement accuracy, it is essential to reduce the amount of the backflow resin.
Accordingly, an object of the present invention is to provide a technique capable of reducing the backflow of resin in a check valve.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, claim 1 is that a check ring is fitted to the screw head, and the check ring is advanced to make the valve open, and to be retracted to make the valve closed. In the check valve of the injection device, which allows resin to pass through a flow path formed between the check ring and the screw head in the valve open state, the flow path is directed from the tip side of the screw head to the screw. The flow path is divided into a flow path, a second flow path, and a third flow path, and the cross-sectional area of the second flow path is set to be larger than that of the first and third flow paths before and after. the length by setting longer than the first-third flow path part, the volume of the second flow passage portion is set sufficiently larger than the volume of the first and third channel portions of the front and rear, and the first flow The volume of the channel is set smaller than the volume of the third channel. Characterized in that it was.
[0006]
By reducing the cross-sectional area of the first flow path portion, the backflow of resin generated at the time of injection is suppressed. The flow rate of the backflow resin is reduced by increasing the cross-sectional area of the second flow path. In addition, by increasing the length of the second flow path portion, a longer time is required for the backflow resin to reach the third flow path portion. That is, by increasing the volume of the second flow path portion, it is possible to delay the compression and pressure increase where the pressure increases with compression. The backflow of the resin is suppressed by reducing the cross-sectional area of the third flow path portion. By integrating the actions of the first to third flow path portions, the check ring can be quickly retracted, that is, the check valve can be closed, and the reverse flow of the resin can be greatly reduced.
Since the volume of the first flow path is set smaller than the volume of the third flow path, the check ring can be closed more quickly.
[0007]
According to a second aspect of the present invention, when the movement margin accompanying the advance and retreat of the check ring is referred to as a stroke of the check ring, the stroke is determined so as to be the same as the cross-sectional area of the third flow path portion. .
The stroke can be made sufficiently small, and the time required for shutting off the check ring can be greatly reduced.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a check valve (first embodiment) of an injection device according to the present invention. The check valve 10 includes a screw head 11, a cylindrical check ring 12 fitted to the screw head 11, and a check ring 12. A valve that is provided at the tip of a screw 14 inserted into the heating cylinder 13 and that allows the resin to pass through a flow path 20 formed between the check ring 12 and the screw head 11 in the resin measuring step. The path 20 is divided into a first flow path section 21, a second flow path section 22, and a third flow path section 23 from the tip end side of the screw head 11 toward the screw 14. Is set to be larger than the cross-sectional area A1 of the first flow path 21 and larger than the cross-sectional area A3 of the third flow path 23, and the length L2 of the second flow path is set to the first / third flow path 21, 23 lengths L1, L3 Ri large by setting, characterized in that the volume V2 of the second channel portion 22 is set sufficiently larger than the volume V1, V3 of the first and third channel portions 21, 23 of the front and rear.
[0009]
Further, when the gap of the first channel portion 21 is δ1, the length is L1, and the gap of the third channel portion 23 is δ3, and the length is L3, the relationship of δ1 <δ3 and L1> L3 is maintained. In addition, the volume V1 of the first channel portion 21 is set smaller than the volume V3 of the third channel portion 23.
[0010]
If the gap δ1 is small, the flow path resistance increases, and if the length L1 is large, the flow path resistance increases. Therefore, the backflow of the resin can be effectively suppressed in the first flow path portion 21.
In addition, since the first and third flow passage portions 21 and 23 have the same outer diameter, there is a difference in inner diameter. As a result, the area of the front surface 24 of the check ring 12 becomes sufficiently large.
[0011]
In the first embodiment, the check ring 12 forms the walls of the second channel portion 22 and the third channel portion 23 by grinding the inner surface of the cylindrical material. With this shaving, the cross-sectional area A3 of the third flow path portion 23 is determined, and the stroke S2 between the sheet 25 and the check ring 12 is determined so that the opening area is substantially the same as the cross-sectional area A3. According to this determination method, the stroke S2 can be made sufficiently small (see FIG. 6A for comparison).
[0012]
Then, as indicated by the arrow, in the measuring step, the resin can be sent to the front of the screw head 11 in the order of the opening of the stroke S2, the third channel portion 23, the second channel portion 22, and the first channel portion 21. .
[0013]
FIG. 2 is an explanatory view of the operation of the check valve according to the present invention at the initial stage of injection. By advancing the screw 14, the resin pressure relatively acts on the front surface 24 of the check ring, and a part of the resin is removed. It enters the first channel portion 21 and then enters the second channel portion 22.
At this time, since the volume V1 of the first flow path portion 21 is sufficiently small to exhibit the function of the throttle portion, the amount of the resin that enters the first flow path portion 21 is reduced.
[0014]
When this small amount of resin flows from the first flow path 21 to the second flow path 22, the cross-sectional area A2 of the second flow path 22 is sufficiently large, so that the flow velocity of the resin decreases. Since the length of the second flow path 22 is sufficiently large, it takes time for the resin of the second flow path 22 to reach the third flow path 23. As a result, the backflow resin reaches the opening of the stroke S2 much later than in the past.
[0015]
When the backflow resin reaches the opening of the stroke S2, the reached resin pushes the back surface of the check ring 12 as shown by an arrow (5). As a result, the closing speed of the check ring 12 decreases, the shutoff is delayed, and the backflow resin flows. It is possible that the amount will increase.
However, in the present invention, the flow of the backflow resin is given a resistance by the throttling action in the first flow path section 21, the speed is reduced in the second flow path section 22, and the resistance to the flow of the backflow resin again in the third flow path section 23. , The arrival of the backflow resin can be greatly delayed.
In addition, since the area of the front surface 24 of the check ring 12 is made sufficiently large, the valve closing force due to the resin pressure becomes larger than before.
Since the valve closing force is large and the wraparound of the resin is delayed, the valve can be closed substantially before the backflow resin reaches the opening of the stroke S2.
[0016]
In determining the dimensions of the first flow path 21, the second flow path 22, and the third flow path 23, the first flow path is defined assuming that the total pressure loss in the flow path 20 is 100%. It is preferable that 50 to 60% is allocated to 21, 25 to 35% is allocated to the third channel portion 23, and the remaining 5 to 25% is allocated to the second channel portion 22.
[0017]
FIG. 3 is an explanatory view of a check valve closing state of the check ring according to the present invention, and shows that the check ring 12 is in contact with the seat 25 and is closed. Since the valve closing state is completed in a shorter time than in the conventional case, the amount of the backflow resin is zero or, if it is generated, very small.
As a result, the injection speed can be increased and the measurement accuracy can be improved.
[0018]
FIG. 4 is a cross-sectional view of a check valve (second embodiment) of the injection device according to the present invention. The check valve 10B also includes a screw head 11 and a cylindrical check ring 12 fitted to the screw head 11. In the measuring step, the valve is a valve that allows resin to pass through a flow path 20 formed between the check ring 12 and the screw head 11. The flow path 20 faces the screw 14 from the distal end side of the screw head 11 to the screw 14. Thus, the first flow path portion 21, the second flow path portion 22, and the third flow path portion 23 are divided, and the cross-sectional area A2 of the second flow path portion 22 is larger than the cross-sectional area A1 of the first flow path portion 21 and By setting the cross-sectional area A3 of the third channel portion 23 to be larger than the cross-sectional area A3, and setting the length L2 of the second channel portion to be larger than the lengths L1 and L3 of the first and third channel portions 21 and 23, Volume V of second flow path 22 Characterized in that the set sufficiently larger than the volume V1, V3 of the first and third channel portions 21, 23 of the front and rear.
[0019]
Further, when the gap of the first channel portion 21 is δ1, the length is L1, and the gap of the third channel portion 23 is δ3, and the length is L3, the relationship of δ1 <δ3 and L1> L3 is maintained. In addition, the volume V1 of the first channel portion 21 is set smaller than the volume V3 of the third channel portion 23.
[0020]
If the gap δ1 is small, the flow path resistance increases, and if the length L1 is large, the flow path resistance increases. Therefore, the backflow of the resin can be effectively suppressed in the first flow path portion 21.
[0021]
More specifically, in the second embodiment, the check ring 12 is kept in a cylindrical shape, and the screw head 11 is ground to form the second flow path portion 22.
The first flow path 21 has resistance to the flow of the backflow resin, the second flow path 22 decelerates the flow, and the third flow path 23 has the resistance to the flow of the reverse flow resin again. Reaching can be greatly delayed.
In addition, since the area of the front surface 24 of the check ring 12 is made sufficiently large, the valve closing force by the resin becomes larger than before.
Since the valve closing force is large and the wraparound of the resin is delayed, the valve can be closed substantially before the backflow resin reaches the opening of the stroke S2.
[0022]
FIG. 5 is a sectional view of a check valve (third embodiment) of the injection device according to the present invention. The check valve 10C also includes a screw head 11 and a cylindrical check ring 12 fitted to the screw head 11. In the measuring step, the valve is a valve that allows resin to pass through a flow path 20 formed between the check ring 12 and the screw head 11. The flow path 20 faces the screw 14 from the distal end side of the screw head 11 to the screw 14. Thus, the first flow path portion 21, the second flow path portion 22, and the third flow path portion 23 are divided, and the cross-sectional area A2 of the second flow path portion 22 is larger than the cross-sectional area A1 of the first flow path portion 21 and By setting the cross-sectional area A3 of the third channel portion 23 to be larger than the cross-sectional area A3, and setting the length L2 of the second channel portion to be larger than the lengths L1 and L3 of the first and third channel portions 21 and 23, Volume V of second flow path 22 Characterized in that the set sufficiently larger than the volume V1, V3 of the first and third channel portions 21, 23 of the front and rear.
[0023]
Further, when the gap of the first channel portion 21 is δ1, the length is L1, and the gap of the third channel portion 23 is δ3, and the length is L3, the relationship of δ1 <δ3 and L1> L3 is maintained. In addition, the volume V1 of the first channel portion 21 is set smaller than the volume V3 of the third channel portion 23.
[0024]
If the gap δ1 is small, the flow path resistance increases, and if the length L1 is large, the flow path resistance increases. Therefore, the backflow of the resin can be effectively suppressed in the first flow path portion 21.
[0025]
Specifically, in the third embodiment, the check ring 12 forms the second flow path portion 22 by grinding the inner surface of the cylindrical material into a U-shaped groove.
The first flow path 21 has resistance to the flow of the backflow resin, the second flow path 22 decelerates the flow, and the third flow path 23 has the resistance to the flow of the reverse flow resin again. Reaching can be greatly delayed.
In addition, since the area of the front surface 24 of the check ring 12 is made sufficiently large, the valve closing force by the resin becomes larger than before.
Since the valve closing force is large and the wraparound of the resin is delayed, the valve can be closed substantially before the backflow resin reaches the opening of the stroke S2.
[0026]
In the first aspect, the volume of the third flow path may be the same as the volume of the first flow path. The point is that the volume of the second channel portion may be set to be sufficiently larger than the volumes of the first and third channel portions before and after.
[0027]
【The invention's effect】
The present invention has the following effects by the above configuration.
In the first aspect, by reducing the cross-sectional area of the first flow path portion, the backflow of the resin generated at the time of injection is suppressed, and by increasing the cross-sectional area of the second flow path portion, the flow velocity of the backflow resin is reduced. In addition, by increasing the length of the second flow path portion, the time until the backflow resin reaches the third flow path portion is increased. That is, by increasing the volume of the second flow path portion, it is possible to delay the compression and pressure increase where the pressure increases with compression. The backflow of the resin is suppressed by reducing the cross-sectional area of the third flow path portion. By integrating the actions of the first to third flow path portions, the check ring can be quickly retracted, that is, the check valve can be closed, and the reverse flow of the resin can be greatly reduced. Since the check valve can be closed quickly, the injection speed can be increased and the measurement accuracy can be improved.
In addition, the capacity of the first flow path is set smaller than the capacity of the third flow path. By narrowing the first flow path, the check valve can be closed more quickly. Therefore, the injection speed can be further increased and the measurement accuracy can be further improved.
[0028]
In the second aspect, when the movement allowance accompanying the advance and retreat of the check ring is referred to as the stroke of the check ring, the stroke is determined so as to be the same as the cross-sectional area of the third flow path portion. The time required for shutting off the check ring can be greatly reduced.
[Brief description of the drawings]
1 is a cross-sectional view of a check ring (first embodiment) of an injection device according to the present invention; FIG. 2 is an explanatory diagram of an initial operation of the check ring of the check valve according to the present invention; FIG. 3 is a check flow according to the present invention; FIG. 4 is a sectional view of the check valve of the injection device according to the present invention (second embodiment). FIG. 5 is a cross-sectional view of the check valve of the injection device according to the present invention. [FIG. 6] Structure and operation diagram of conventional check valve [Description of reference numerals]
10, 10B, 10C: check valve, 11: screw head, 12: check ring, 13: heating cylinder, 14: screw, 20: channel, 21: first channel, 22: second channel, Reference numeral 23: third channel portion, 24: front surface of the check ring, 25: sheet, A1 to A3: cross-sectional area of the channel portion, L1 to L3: length of the channel portion, V1 to V3: volume of the channel portion , Δ1, δ3 ... gaps in the flow path portion.

Claims

A check ring is fitted to the screw head, and the check ring can be advanced to open the valve and retracted to make the valve closed.In the resin measurement process, the check ring and the screw head can be opened. In a check valve of an injection device capable of allowing resin to pass through a flow path formed therebetween,
The flow path is divided into a first flow path, a second flow path, and a third flow path from the tip side of the screw head toward the screw,
By setting the cross-sectional area of the second flow path to be larger than that of the front and rear first and third flow paths, and setting the length of the second flow path to be longer than the first and third flow paths, The volume of the two flow paths is set to be sufficiently larger than the volumes of the first and third flow paths before and after ,
The check valve of the injection device is characterized in that the volume of the first flow path is set smaller than the volume of the third flow path .

2. The stroke for moving the check ring forward and backward is referred to as a check ring stroke, and the stroke is determined so as to be the same as the cross-sectional area of the third flow path portion. The check valve of the injection device according to claim 1.