JPH0478093B2 - - Google Patents
Info
- Publication number
- JPH0478093B2 JPH0478093B2 JP62077664A JP7766487A JPH0478093B2 JP H0478093 B2 JPH0478093 B2 JP H0478093B2 JP 62077664 A JP62077664 A JP 62077664A JP 7766487 A JP7766487 A JP 7766487A JP H0478093 B2 JPH0478093 B2 JP H0478093B2
- Authority
- JP
- Japan
- Prior art keywords
- mold
- pressure
- resin
- resin pressure
- injection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Injection Moulding Of Plastics Or The Like (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、射出成形方法に係わり、特に、バ
リや肉ひけ、そり等の製品不良の発生を防止しつ
つ限られた型閉め力で大きな投影面積を有する製
品を成形する技術に関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an injection molding method, and in particular, the present invention relates to an injection molding method, and in particular, it is possible to prevent product defects such as burrs, sink marks, and warpage, and to produce a large mold with a limited mold closing force. This relates to technology for molding products with projected areas.
〔従来の技術〕
一般に、射出成形は溶融樹脂をキヤビテイ内に
射出充填する射出工程と、キヤビテイ内が樹脂で
満たされた後に型内樹脂に圧力をかけて保持する
保圧工程とからなる。この場合、型内樹脂圧をい
かに制御するかは、製品にバリや肉ひけあるいは
そり等の有害な製品不良の発生を防止する上で極
めて重要である。[Prior Art] Generally, injection molding consists of an injection process in which molten resin is injected and filled into a cavity, and a pressure holding process in which the resin in the mold is held under pressure after the cavity is filled with resin. In this case, how to control the resin pressure inside the mold is extremely important in order to prevent harmful product defects such as burrs, sink marks, and warpage from occurring in the product.
このような観点から、従来においては次のよう
にして射出成形を行つている。すなわち、第２図
は従来の射出成形方法における型内樹脂圧の変化
を示す線図であつて、樹脂の射出開始から冷却固
化に至るまでの型内樹脂圧の変化を示すものであ
る。まず、成形機から溶融樹脂を射出する。する
と型内樹脂圧は図中Ａで示す範囲で緩やかに上昇
し、充填の最終段階（図中Ｂで示す範囲）におい
て急激に増加する。これは、キヤビテイ内が樹脂
で満たされるために、射出圧力が静水圧となつて
型に加わるためである。この型内樹脂圧P1は、
製品の肉ひけやそりの発生を防止する上で必要と
される圧力であり、この圧力によつて溶融樹脂が
型の内部に〓間なく充填される。 From this point of view, injection molding has conventionally been carried out as follows. That is, FIG. 2 is a diagram showing the change in the resin pressure in the mold in the conventional injection molding method, and shows the change in the resin pressure in the mold from the start of resin injection to cooling solidification. First, molten resin is injected from a molding machine. Then, the resin pressure in the mold gradually increases in the range indicated by A in the figure, and rapidly increases at the final stage of filling (range indicated by B in the figure). This is because the injection pressure becomes hydrostatic pressure and is applied to the mold as the cavity is filled with resin. This in-mold resin pressure P 1 is
This pressure is necessary to prevent the product from sinking or warping, and this pressure quickly fills the mold with molten resin.
次に、型内樹脂圧を若干下げて保圧を行う。こ
の保圧工程は、樹脂の冷却による収縮量に見合つ
た樹脂を補充するための工程であり、図中C1と
C2の範囲に示すように２段階の圧力設定により
行う。ここで、C1で示す段階では溶融樹脂の表
面に形成された固化層を型に押し付けて成形品の
外表部における肉ひけやそりを修正する。また、
C2で示す段階では成形品の肉ひけやそりを更に
修正する。 Next, the resin pressure in the mold is slightly lowered and pressure holding is performed. This pressure holding process is a process to replenish the resin in an amount commensurate with the amount of shrinkage due to resin cooling, and is indicated by C 1 in the figure.
The pressure is set in two stages as shown in the C2 range. Here, in the step indicated by C1 , the solidified layer formed on the surface of the molten resin is pressed against a mold to correct any sink marks or warpage on the outer surface of the molded product. Also,
In the step shown in C 2 , the molded product is further corrected for sink marks and warpage.
ところで、射出成形において成形機に必要とさ
れる型締め力は、（最大型内樹脂圧）×（製品の投
影面積）で示され、この能力を越えた場合には型
開き量が大きくなるため製品にバリが発生する。
ところが、上記射出成形方法においては、型内が
溶融樹脂で満たされるときに型内樹脂圧を最大に
するものであるから、第３図に示すように、僅か
に型が開いただけで溶融樹脂が型の分割面どうし
の間に生じた〓間に入り込んでバリＳが発生す
る。一方、成形品に肉ひけやそりが生じないよう
にするためには、型内樹脂圧を一定の値以上にす
る必要がある。したがつて、バリの発生を防止
し、なおかつ肉ひけやそり等の発生を防止するた
めには製品の投影面積を大幅に制限しなければな
らず、このため製造効率が悪いという問題があつ
た。
By the way, the mold clamping force required by the molding machine in injection molding is expressed as (maximum resin pressure in the mold) x (projected area of the product), and if this capacity is exceeded, the amount of mold opening will increase. Burrs appear on the product.
However, in the injection molding method described above, the resin pressure inside the mold is maximized when the inside of the mold is filled with molten resin, so as shown in Figure 3, even if the mold is slightly opened, the molten resin is Burrs S are generated by getting into the gaps created between the dividing surfaces of the mold. On the other hand, in order to prevent sink marks and warpage from occurring in the molded product, it is necessary to increase the resin pressure within the mold to a certain value or higher. Therefore, in order to prevent the occurrence of burrs, as well as sink marks and warpage, it is necessary to significantly limit the projected area of the product, resulting in the problem of poor manufacturing efficiency. .
この発明は、このような問題点を解決するため
になされたもので、バリや肉ひけ等を生じさせる
ことなく成形品の投影面積を大きくすることがで
き、したがつて製造効率を向上させることができ
る射出成形方法を提供することを目的としてい
る。
This invention was made to solve these problems, and it is possible to increase the projected area of a molded product without causing burrs or sink marks, thereby improving manufacturing efficiency. The purpose is to provide an injection molding method that allows for
この発明の射出成形方法は、キヤビテイ内へ溶
融樹脂を射出し、キヤビテイ内が溶融樹脂で満た
される直前に射出圧力を下げ、次に型内樹脂圧を
徐々に増加させて射出時の最大型内樹脂圧よりも
大きな型内樹脂圧で保圧を行うようにした射出成
形方法において、前記保圧を多段階の圧力制御の
もとに行うとともに、初段階の保圧における型内
樹脂圧を、最大型内樹脂圧に至らない範囲内で、
その前半における上昇率を大きくかつ後半におけ
る上昇率を徐々に減少させ、また、次段階の保圧
における型内樹脂圧を、最大型内樹脂圧へ向け、
上昇率を徐々に減少させつつ上昇させ、かつ、前
記最大型内樹脂圧に至つたのちに、この最大型内
樹脂圧から徐々に減少させることを特徴とする。
The injection molding method of this invention injects molten resin into a cavity, lowers the injection pressure just before the cavity is filled with the molten resin, and then gradually increases the resin pressure in the mold to reach the maximum mold inside at the time of injection. In an injection molding method in which pressure is held at a resin pressure in the mold that is greater than the resin pressure, the holding pressure is performed under multi-stage pressure control, and the resin pressure in the mold at the first stage of holding pressure is Within the range that does not reach the maximum resin pressure in the mold,
The rate of increase in the first half is increased and the rate of increase in the second half is gradually decreased, and the in-mold resin pressure in the next stage of holding pressure is directed to the maximum in-mold resin pressure.
The method is characterized in that the rate of increase is gradually decreased and the pressure is increased, and after reaching the maximum resin pressure in the mold, the pressure is gradually decreased from the maximum resin pressure in the mold.
射出工程の終了直前で射出圧力を下げるから、
樹脂が固化していない時点での型開きを防止す
る。一方、保圧工程においては型内樹脂圧の増加
に伴い型開き量も増加するが、溶融樹脂の表面が
漸次冷却固化するので溶融樹脂が型の分割面どう
しの間に入り込むことが少ない。
Because the injection pressure is lowered just before the end of the injection process,
Prevents the mold from opening when the resin is not solidified. On the other hand, in the holding pressure step, the amount of mold opening increases as the resin pressure within the mold increases, but since the surface of the molten resin gradually cools and solidifies, the molten resin rarely enters between the dividing surfaces of the mold.
以下、本発明の一実施例について第１図を参照
しながら説明する。実施例の射出成形方法では成
形機の能力の２倍の投影面積の成形品を必要な最
大型内樹脂圧で射出成形する。このため、型開き
量も許容される量のほぼ２倍となるが、次のよう
にしてバリの発生を防止する。
An embodiment of the present invention will be described below with reference to FIG. In the injection molding method of the embodiment, a molded product having a projected area twice the capacity of the molding machine is injection molded at the maximum required in-mold resin pressure. For this reason, the amount of mold opening is approximately twice the allowable amount, but the occurrence of burrs is prevented as follows.
すなわち、第１図は樹脂の射出開始から冷却固
化に至るまでの型内樹脂圧の変化を示す線図であ
る。この射出成形方法では、射出工程の後に保圧
工程を第３段階に別けて行う。まず、成形機から
キヤビテイ内に溶融樹脂を射出充填する。このと
き型内樹脂圧は次第に上昇する。そして、型内が
溶融樹脂で満たされる直前で射出圧をゼロにし
（圧抜工程）、保圧工程の第１段階に移行する。な
お、射出開始から圧抜工程に移行するまでの時間
（図中Ａで示す時間）は0.5〜1.0秒とする。また、
このときの最大型内樹脂圧P0は前記従来例の最
大型内樹脂圧の約1/2とする。そして、射出圧ゼ
ロの状態を図中C0で示す時間（この実施例では
0.5秒以下）保持する。このように、射出圧を一
旦ゼロにして保持することにより、一度開きかけ
た型が成形機の型締め力で互いに締め付けられ、
かつその間に溶融樹脂の表面に固化層が形成され
る。 That is, FIG. 1 is a diagram showing changes in resin pressure within the mold from the start of resin injection to cooling solidification. In this injection molding method, a pressure holding step is performed in a third stage after the injection step. First, molten resin is injected and filled into the cavity from a molding machine. At this time, the resin pressure inside the mold gradually increases. Immediately before the inside of the mold is filled with molten resin, the injection pressure is reduced to zero (pressure release process), and the process moves to the first stage of the pressure holding process. Note that the time from the start of injection to the transition to the pressure relief process (the time indicated by A in the figure) is 0.5 to 1.0 seconds. Also,
The maximum in-mold resin pressure P 0 at this time is approximately 1/2 of the maximum in-mold resin pressure in the conventional example. Then, the time when the injection pressure is zero is indicated by C 0 in the figure (in this example,
0.5 seconds or less). In this way, by temporarily setting the injection pressure to zero and maintaining it, the molds that are about to open are tightened together by the mold clamping force of the molding machine.
During this time, a solidified layer is formed on the surface of the molten resin.
次に、保持時間がC0に達したら型内樹脂圧を
徐々に増加させ、保圧工程の第１段階に移行す
る。保圧工程の第２段階は、溶融樹脂の表面に形
成された硬化層を押し広げ、これによつて硬化層
と型の内面との間に生じている〓間を埋めて肉ひ
けを除去する工程である。このとき、型内樹脂圧
の増加によりしだいに型が開いてゆくが、上記表
面固化層の存在により樹脂が型の間にはみ出すこ
とがない。しかし、型内樹脂により硬化層が破壊
されないような型内樹脂圧の制御と時間（図中
C1で示す）の設定を行う必要ある。このため、
型内樹脂圧を最初やや急激に増加させるが増加率
が徐々に小さくなるように変化させるとともに、
その時間C1を1.0〜2.0秒に設定して硬化層の厚さ
を充分厚くする。すなわち、型内樹脂圧は第１段
階の前半において硬化層を押広げるように作用す
るが、硬化層が型内面に密着した後においては硬
化層を破壊するように作用するためである。 Next, when the holding time reaches C 0 , the resin pressure in the mold is gradually increased, and the process moves to the first stage of the pressure holding process. The second stage of the pressure holding process is to spread out the hardened layer formed on the surface of the molten resin, thereby filling the gap between the hardening layer and the inner surface of the mold and removing the sink marks. It is a process. At this time, the mold gradually opens as the resin pressure inside the mold increases, but the resin does not protrude between the molds due to the presence of the surface solidified layer. However, it is difficult to control the resin pressure in the mold and the time (in the figure) so that the cured layer is not destroyed by the resin in the mold.
It is necessary to configure the settings shown in C 1 ). For this reason,
The resin pressure in the mold is initially increased somewhat rapidly, but the rate of increase is gradually reduced, and
The time C1 is set to 1.0 to 2.0 seconds to make the cured layer sufficiently thick. That is, the in-mold resin pressure acts to spread the cured layer in the first half of the first stage, but after the cured layer comes into close contact with the inner surface of the mold, it acts to destroy the cured layer.
次に型内樹脂圧の上昇率を上げて保圧工程の第
２段階に移行する。第２段階は成形品の肉ひけや
そり等をさらに修正する工程であり、第１段階と
同様に、型内樹脂圧の増加率を徐々に小さくし、
第２段階の中間時点において最大となるように制
御する。しかし、第２段階では型内樹脂圧が最大
となるから型開き量も最大となり、しかも、製品
の表面は固化しているが内部はまだ溶融状態にあ
る。したがつて、第１段階と同様に溶融樹脂が硬
化層を破壊しないような型内樹脂圧の制御と時間
（図中C2で示す）の設定を行う必要がある。この
ため、この工程では型内樹脂圧をその変化曲線が
第１段階のものより緩いカーブとなるように制御
するとともに、時間C2を3.0〜6.0秒に設定する。
一方、このときの最大型内樹脂圧P1は、射出時
の最大型内樹脂圧P0の約２倍に設定する。この
最大型内圧力は成形品の肉ひけやそりを修正する
ために必要とされる値である。なお、保圧工程の
第２段階が終了したら圧力保持を解除し、所定時
間成形品の冷却を行う。このとき、成形機の型締
め力によつて型が締め付けられ、型開き量がゼロ
となる。 Next, the rate of increase in the resin pressure in the mold is increased and the process moves to the second stage of the pressure holding process. The second stage is a process for further correcting fillet sinks, warpage, etc. of the molded product.Similar to the first stage, the rate of increase in resin pressure in the mold is gradually reduced,
It is controlled so that it reaches the maximum at the middle point of the second stage. However, in the second stage, the resin pressure inside the mold is at its maximum, so the amount of mold opening is also at its maximum, and although the surface of the product is solidified, the inside is still in a molten state. Therefore, as in the first stage, it is necessary to control the resin pressure in the mold and set the time (indicated by C2 in the figure) so that the molten resin does not destroy the cured layer. Therefore, in this step, the resin pressure in the mold is controlled so that its change curve becomes a gentler curve than that in the first stage, and the time C2 is set to 3.0 to 6.0 seconds.
On the other hand, the maximum in-mold resin pressure P 1 at this time is set to approximately twice the maximum in-mold resin pressure P 0 during injection. This maximum in-mold pressure is the value required to correct the sinkage and warpage of the molded product. Note that when the second stage of the pressure holding process is completed, the pressure holding is canceled and the molded product is cooled for a predetermined period of time. At this time, the mold is tightened by the mold clamping force of the molding machine, and the amount of mold opening becomes zero.
このような射出成形方法においては、射出終了
直前の型内樹脂圧の急激な増加を回避して型開き
を防止し、かつ溶融樹脂の表面に形成される硬化
層を破壊しなように型内樹脂圧を徐々に増加させ
て型内樹脂圧を最大にするから、成形品にバリを
発生させることなく肉ひけやそり等の発生を防止
することができる。したがつて、成形品の投影面
積を成形機の能力の２倍以上に設定しても成形品
の品質になんら支障を来すことがなく、製造効率
を大幅に向上させることができる。また、固化層
を破壊せずに成形するものであるから、冷却工程
において成形機の型締め力により型開き量がゼロ
となる。したがつて、成形品の収縮率を一定にす
ることができ、製品の寸法精度を大幅に向上させ
ることができる。 In such an injection molding method, the pressure inside the mold is prevented from rapidly increasing just before the end of injection to prevent the mold from opening, and the inside of the mold is Since the resin pressure in the mold is maximized by gradually increasing the resin pressure, it is possible to prevent the occurrence of sink marks, warpage, etc. without causing burrs on the molded product. Therefore, even if the projected area of the molded product is set to be more than twice the capacity of the molding machine, the quality of the molded product will not be affected at all, and manufacturing efficiency can be greatly improved. Furthermore, since the molding is performed without destroying the solidified layer, the mold opening amount becomes zero due to the mold clamping force of the molding machine during the cooling process. Therefore, the shrinkage rate of the molded product can be kept constant, and the dimensional accuracy of the product can be significantly improved.
以上説明したようにこの発明の射出成形方法に
おいては、キヤビテイ内へ溶融樹脂を射出し、キ
ヤビテイ内が溶融樹脂で満たされる直前に射出圧
力を下げ、次に型内樹脂圧を徐々に増加させて射
出時の最大型内樹脂圧よりも大きな型内樹脂圧で
保圧を行うようにした射出成形方法において、前
記保圧を多段階の圧力制御のもとに行うととも
に、初段階の保圧における型内樹脂圧を、最大型
内樹脂圧に至らない範囲内で、その前半における
上昇率を大きくかつ後半における上昇率を徐々に
減少させ、また、次段階の保圧における型内樹脂
圧を、最大型内樹脂圧へ向け、上昇率を徐々に減
少させつつ上昇させ、かつ、前記最大型内樹脂圧
に至つたのちに、この最大型内樹脂圧から徐々に
減少させることを特徴とするもので、充填された
樹脂表面に硬化層を形成するとともに、この硬化
層の破壊を防止しつつ有効な樹脂圧を与えること
ができ、これによつて、高い樹脂圧による成形
を、ばりや肉ひけ等を発生させることなく実施す
ることができ、製品の寸法精度を大幅に向上させ
ることができるとともに、成形品の投影面積を大
きくすることができ、したがつて製造効率を向上
させることができる。
As explained above, in the injection molding method of the present invention, molten resin is injected into the cavity, the injection pressure is lowered just before the cavity is filled with the molten resin, and then the resin pressure in the mold is gradually increased. In an injection molding method in which pressure is held at a resin pressure in the mold that is greater than the maximum resin pressure in the mold during injection, the holding pressure is performed under multi-stage pressure control, and the holding pressure is The rate of increase in the first half of the resin pressure in the mold is increased and the rate of increase in the second half is gradually decreased within a range that does not reach the maximum resin pressure in the mold, and the resin pressure in the mold at the next stage of holding pressure is The resin pressure in the mold is increased while gradually decreasing the rate of increase toward the maximum resin pressure in the mold, and after reaching the maximum resin pressure in the mold, the pressure is gradually decreased from the maximum resin pressure in the mold. In addition to forming a hardened layer on the surface of the filled resin, it is possible to apply effective resin pressure while preventing the destruction of this hardened layer.This allows molding with high resin pressure to be performed without causing burrs or sink marks. This can be carried out without causing problems such as the like, and the dimensional accuracy of the product can be greatly improved, and the projected area of the molded product can be increased, thereby improving manufacturing efficiency.
第１図は本発明の一実施例を示す図であつて、
型内樹脂圧の変化を示す線図、第２図は従来の射
出成形方法における型内樹脂圧の変化を示す線
図、第３図は射出工程終了時の型の分割面の状態
を示す拡大側断面図である。
FIG. 1 is a diagram showing an embodiment of the present invention,
A diagram showing changes in the resin pressure inside the mold. Figure 2 is a diagram showing changes in the resin pressure inside the mold in the conventional injection molding method. Figure 3 is an enlarged diagram showing the state of the split surface of the mold at the end of the injection process. FIG.
Claims (1)
イ内が溶融樹脂で満たされる直前に射出圧力を下
げ、次に型内樹脂圧を徐々に増加させて射出時の
最大型内樹脂圧よりも大きな型内樹脂圧で保圧を
行うようにした射出成形方法において、前記保圧
を多段階の圧力制御のもとに行うとともに、初段
階の保圧における型内樹脂圧を、最大型内樹脂圧
に至らない範囲内で、その前半における上昇率を
大きくかつ後半における上昇率を徐々に減少さ
せ、また、次段階の保圧における型内樹脂圧を、
最大型内樹脂圧へ向け、上昇率を徐々に減少させ
つつ上昇させ、かつ、前記最大型内樹脂圧に至つ
たのちに、この最大型内樹脂圧から徐々に減少さ
せることを特徴とする射出成形方法。1 Inject the molten resin into the cavity, lower the injection pressure just before the cavity is filled with the molten resin, and then gradually increase the resin pressure in the mold so that the resin pressure in the mold is higher than the maximum resin pressure in the mold at the time of injection. In an injection molding method in which holding pressure is performed using resin pressure, the holding pressure is performed under multi-stage pressure control, and the resin pressure in the mold at the first stage of holding pressure is controlled until the resin pressure in the mold reaches the maximum resin pressure in the mold. Increase the rate of increase in the first half and gradually decrease the rate of increase in the second half, within the range of
Injection characterized by increasing the resin pressure in the mold while gradually decreasing the rate of increase toward the maximum resin pressure in the mold, and gradually decreasing the resin pressure in the mold after reaching the maximum resin pressure in the mold. Molding method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7766487A JPS63242621A (en) | 1987-03-31 | 1987-03-31 | Method for injection molding |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7766487A JPS63242621A (en) | 1987-03-31 | 1987-03-31 | Method for injection molding |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63242621A JPS63242621A (en) | 1988-10-07 |
| JPH0478093B2 true JPH0478093B2 (en) | 1992-12-10 |
Family
ID=13640142
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7766487A Granted JPS63242621A (en) | 1987-03-31 | 1987-03-31 | Method for injection molding |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63242621A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4537441B2 (en) * | 2007-12-10 | 2010-09-01 | 住友重機械工業株式会社 | Control method of injection molding machine |
| JP5954553B2 (en) * | 2014-07-18 | 2016-07-20 | 太平洋通商株式会社 | Method for manufacturing storage frame |
| CN106696192B (en) * | 2016-12-23 | 2018-11-09 | 河南工程学院 | Micro- injection-compression mold |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5729257B2 (en) * | 1973-11-21 | 1982-06-22 | ||
| JPS5774135A (en) * | 1980-10-29 | 1982-05-10 | Toshiba Mach Co Ltd | High pressure injection molding method and device therefor |
| JPS59165634A (en) * | 1983-03-11 | 1984-09-18 | Mitsubishi Heavy Ind Ltd | Injection molding method |
-
1987
- 1987-03-31 JP JP7766487A patent/JPS63242621A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63242621A (en) | 1988-10-07 |
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