JP4055104B2 - Nozzle temperature control method and nozzle temperature control apparatus for injection molding machine - Google Patents

Description

【００２０】
前記のように、各加熱ゾーンＨ１，Ｈ２に属する両側の各温度センサー（７ａ，７ｂ）、（７ｂ，７ｃ）により検出される温度（Ｔ１，Ｔ２）、（Ｔ３，Ｔ４）に重み付けをして各仮想温度ＰＶ１，ＰＶ２を求めて、これらの仮想温度ＰＶ１，ＰＶ２により各温度調節計１２，１３で各ヒータ４，５の温度を制御すると、実際に測定していない各加熱ゾーンＨ１，Ｈ２内の見かけ上の温度（仮想温度）が検出された状態となり、各温度調節計１２，１３において、前記仮想温度から射出ノズルの軸方向における各加熱ゾーンに対する加熱温度の制御値の設定が適切に行え、これにより、各ヒータ４，５の加熱温度の制御が適確に行われる。しかも、各重み設定器１０，１１での重み係数Ａ，Ｂ，Ｃ，Ｄを適宜に変えることにより、各仮想温度ＰＶ１，ＰＶ２を変えて、各加熱ゾーンＨ１，Ｈ２の各ヒータ４，５の加熱温度を調節することができるので、成形に使用する樹脂材料等に対応して、射出ノズル３の軸方向に適宜温度差を有する滑らかな温度勾配を持たせた加熱制御ができると共に、成形サイクルの周期に同期して変動することのない加熱温度の制御を行うことができる。
【００２１】
前記実施の形態のノズル温度制御装置によれば、重み設定器１０，１１で重み係数を変えることにより、仮想温度ＰＶ１，ＰＶ２が変わるが、これは、重み係数Ａ〜Ｄの大きさに応じて第１の加熱ゾーンＨ１における温度センサー７ａ，７ｂの一方を、または第２の加熱ゾーンＨ２における温度センサー７ｂ，７ｃの一方を、それぞれ、あたかも射出ノズル３の軸方向に位置を移動して設置し、その移設した温度センサーで前記仮想温度ＰＶ１，ＰＶ２に相当する温度を検出したかのように作用されるので、特に、射出ノズル３の第１の加熱ゾーンＨ１の前端側に設けた第１の温度センサー７ａでの検出温度にもとづき第１のヒータ４の加熱温度を制御する場合に比べて、金型の温度にあまり影響されることなく、加熱温度の変動をなくすることができる。
【００２２】
すなわち、前記温度センサー７ａ，７ｂ，７ｃの位置を成形品が変わる毎に変えることは物理的に不可能に近いが、本実施の形態のノズル温度制御装置では、重み係数Ａ〜Ｄを重み設定器１０，１１で変えることにより、各加熱ゾーンのそれぞれに対応させて設けた１つの温度センサー（仮想温度センサー）の位置を、射出ノズルの軸方向に適宜に変えて設定（移設）したのと同等の効果を得ることができ、金型の温度の影響が少なく、安定した射出ノズル３の加熱温度を設定することができる。
【００２３】
因みに、図２は、前記実施の形態のノズル温度制御装置により、重み係数を変えて射出ノズル３を加熱制御して実成形を行った場合における射出ノズル３の軸方向における各温度測定位置Ｓ，Ｓ１，Ｓ２，Ｓ３，Ｓ４，Ｓ５における温度を測定し、その温度勾配を示した線図である。
使用した樹脂材料はポリエチレンで、各温度調節計１２，１３における各ヒータ４，５に対する目標加熱温度の設定値は、それぞれ、２１０℃、２３０℃（ケースｆの場合は、それぞれ、２２５℃、２３０℃）である。また、各重み付け設定器１０，１１における重み係数は、
ケースａの場合で、Ａ＝０、Ｂ＝１、Ｃ＝１、Ｄ＝０
ケースｂの場合で、Ａ＝０．２５、Ｂ＝０．７５、Ｃ＝１、Ｄ＝０
ケースｃの場合で、Ａ＝０．５、Ｂ＝０．５、Ｃ＝１、Ｄ＝０
ケースｄの場合で、Ａ＝０．７５、Ｂ＝０．２５、Ｃ＝１、Ｄ＝０
ケースｅの場合で、Ａ＝１、Ｂ＝０、Ｃ＝１、Ｄ＝０
ケースｆの場合で、Ａ＝１、Ｂ＝０、Ｃ＝１、Ｄ＝０
【００２４】
図２によれば、第２の加熱ゾーンＨ２の温度センサー７ｂ，７ｃの検出温度に対する重み係数Ｃ，Ｄの設定値を所定値に固定（Ｃ＝１，Ｄ＝０）しておいて、第１の加熱ゾーンＨ１の温度センサー７ａ，７ｂの検出温度に対する重み係数Ａ，Ｂの設定値を変化させると、それらの設定値に関わらず、射出ノズル３の最後端側の温度測定位置Ｓ５の一定の温度を起点にして、温度測定位置Ｓ４，Ｓ３，Ｓ２，Ｓ１の順に射出ノズル３の最前端側の温度測定位置Ｓに行くに従って、徐々に温度が滑らかに低下する温度勾配となり、その温度勾配の度合は、重み係数Ａが大きく（重み係数Ｂが小さく）なるほど、急勾配になることが判明した。このことから、特に、射出ノズル３の先端側の加熱ゾーンに属する温度センサー７ａ，７ｂの検出温度に対する重み係数を、樹脂材料の種類や温度特性等に応じて変更設定することにより、射出ノズル３の軸方向における温度勾配を適切に形成し、安定した成形を行うことができることが明らかとなった。
【００２５】
なお、前記実施の形態においては、前記射出ノズル３の中央に取り付けた第２の温度センサー７ｂが、第１の加熱ゾーンＨ１における後側（隣接する第２の加熱ゾーンＨ２側）の温度Ｔ２を検出する温度センサーと、第２の加熱ゾーンＨ２における前側（隣接する第１の加熱ゾーンＨ１側）の温度Ｔ３を検出する温度センサーとに兼用されているので、温度センサーの個数を節約できて好ましいが、兼用させずに個別に設けた温度センサーによって前記温度Ｔ２，Ｔ３を検出するようにしてもよい。射出ノズル３の軸方向に近接した位置に設ける２つの温度センサーは実質的に１つの温度センサーと同一視することができる。
【００２６】
また、前記実施の形態においては、射出ノズル３の軸方向に２つに区画された第１、第２の加熱ゾーンＨ１，Ｈ２に、それぞれ、第１、第２のヒータ４，５を装着した構成にしたが、射出ノズル３の加熱ゾーンとそれに対応して設けるヒータの個数は、２つに限らず、射出ノズルの大きさに応じて１つまたは３つ以上の個数であってもよく、ｎ個（ｎは正の整数）設けることができる。
そして、ｎ個の加熱ゾーン（ヒータ）に対して、温度センサーを（ｎ＋１）個設けて、隣接する加熱ゾーンの間に設ける温度センサーを相互の加熱ゾーンに対して兼用させると共に、演算回路、重み設定器、温度調節計、開閉器からなる制御器をｎ個設けて、該制御器により各加熱ゾーンに対応して設けたヒータの加熱温度を個別に調節するようにしてもよい。
【００２７】
また、前記実施の形態においては、射出ノズル３の軸方向に区画された各加熱ゾーンＨ１，Ｈ２に、ヒータ４，５をそれぞれ１個ずつ設けているが、これに限らず、一方もしくは両方の加熱ゾーンに複数個のヒータを設けて、各加熱ゾーンの両側付近に設けた温度センサーの検出温度によって、各加熱ゾーンに対して求められた仮想温度にもとづき、それぞれ、各加熱ゾーンに属する複数個のヒータを温度制御するようにしてもよい。
【００２８】
また、前記実施の形態においては、前記重み係数を設定する第１、第２の重み設定器１０，１１は、それぞれ、第１、第２の演算回路８，９に個別の機器として接続された構成になっているが、これに限らず、重み設定器１０，１１と同様な機能を有するものを第１、第２の演算回路８，９に内蔵させるようにしてもよい。さらに、重み設定器１０，１１において重み係数Ａ，Ｂ，Ｃ，Ｄを、Ａ＋Ｂ＝１、Ｃ＋Ｄ＝１の関係式で設定されるようにしたが、これに限らず、他の関係式で設定してもよく、それぞれ、個別に設定するようにしてもよい。
【００２９】
【発明の効果】
以上説明したように、本発明によれば以下の優れた効果を奏する。請求項１に係る射出成形機のノズル温度制御方法によれば、各ヒータの両側の２つの温度センサーで検出された射出ノズルの加熱温度が、それぞれ重み係数を可変設定することで重み付けされて、各ヒータのそれぞれに対する温度制御用の仮想温度が求められ、この仮想温度にもとづいて温度調節計が各ヒータの加熱温度を個別に制御するので、重み係数を適宜に変えて各温度センサーの検出温度に対する重み付けを適切に設定することにより適切な各仮想温度を得ることができ、射出ノズルの軸方向に沿う加熱温度の温度勾配が好適な状態になるように各ヒータを加熱制御することができる。
しかも、重み係数を適宜に変えことにより、各仮想温度を変えて、各加熱ゾーンのヒータの加熱温度を適宜に調節することができるので、成形に使用する樹脂材料等に対応して、射出ノズルの軸方向に適切な温度差を有する滑らかな温度勾配を持たせた加熱制御を容易に行うことができる。
【００３０】
請求項２に係る射出成形機のノズル温度制御装置によれば、温度センサーによる検出温度に重み付けをして実際に測定していない各加熱ゾーン内の見かけ上の温度（仮想温度）を検出した状態を得ることができ、各温度調節計において、前記仮想温度から射出ノズルの軸方向における各加熱ゾーンの加熱温度の制御値の設定を適切に行うことができるので、各加熱ゾーンにおけるヒータの加熱温度の制御を適確に行うことができ、射出ノズルの軸方向における温度勾配を適宜に設定できて、成形サイクルの周期に同期して変動することのない加熱温度の制御を確実に行うことができる。
しかも、各重み設定器での重み係数を適宜に変えことにより、各仮想温度を変えて、各加熱ゾーンのヒータの加熱温度を適宜に調節することができるので、成形に使用する樹脂材料等に対応して、射出ノズルの軸方向に適切な温度差を有する滑らかな温度勾配を持たせた加熱制御を容易に行うことができる。
また、互いに隣接する加熱ゾーン側に位置する２つの温度センサーが１つの温度センサーで兼用されるので、温度センサーの個数を節減することができ、構造が簡単になって故障の確率も減り、保守点検も容易に行うことができる。
【図面の簡単な説明】
【図１】 本発明に係る射出成形機のノズル温度制御装置の一実施の形態を示すブロック図である。
【図２】 同制御装置により重み付け係数を変えて射出ノズルを加熱制御して実成形した一例における射出ノズルの軸方向の温度勾配を示す線図である。
【図３】 従来のノズル温度制御装置により射出ノズルを加熱制御して実成形した場合の射出ノズルの温度測定の状況を示す説明図である。
【図４】 同温度測定によって得られた射出ノズルの各測定点における温度の変動の状況を示す線図である。
【符号の説明】
１ 加熱筒
２ 射出スクリュ
３ 射出ノズル
４、５ ヒータ
７，７ａ，７ｂ，７ｃ 温度センサー
８，９ 演算回路（制御器）
１０，１１ 重み設定器
１２，１３ 温度調節計
１４、１５ 開閉器
Ｈ１，Ｈ２ 加熱ゾーン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nozzle temperature control method and a nozzle temperature control device for controlling the temperature of an injection nozzle provided at the tip of a heating cylinder of an injection molding machine.
[0002]
[Prior art]
In the injection molding machine, the temperature of the injection nozzle provided in the heating cylinder is lowered when the tip of the injection nozzle is brought into contact with a low-temperature mold during the injection process. A heater is attached to each heating zone to heat the injection nozzle, and the heating temperature of the heater is adjusted by a temperature controller based on the temperature detected by the temperature sensor embedded in the injection nozzle in a one-to-one correspondence with each heating zone. The temperature of the injection nozzle is adjusted individually so that the temperature difference between the front end side and the rear end side does not become large (Japanese Utility Model Publication No. 5-12020).
[0003]
[Problems to be solved by the invention]
However, since a heater cannot be installed in the vicinity of the mold at the tip of the injection nozzle, in the control of the heating temperature by the heater provided in the heating zone away from the die and the temperature sensor corresponding to the heating zone, the injection is performed. The heating temperature at the tip of the nozzle cannot be adjusted properly, and the actual temperature is much lower than the temperature on the heating zone, and the temperature in each heating zone fluctuates greatly in synchronization with the molding cycle. There is a problem to do.
[0004]
As shown in FIG. 3, the heaters 23a and 23b are attached to the heating zones 22a and 22b on the outer periphery of the injection nozzle 21 of the heating cylinder 20 brought into contact with the mold K, and the temperature sensor P is connected to the injection nozzle 21. , P1, P2, P3, P4, and P5 are attached to positions S1, S2, S3, S4, and S5 (positions within the heating zone) in order from the tip side position S (position outside the heating zone), and the known temperature control Based on the temperature detected by the temperature sensors P2 and P4 of the heating zones 22a and 22b, the heating temperature of the heaters 23a and 23b is adjusted so that the tip of the injection nozzle 21 is brought into contact with the mold K and actually injected. Molding was performed, and the temperature t, t1, t2, t3, t4, and t5 were measured with the temperature sensors P, P1, P2, P3 , P4, and P5.
[0005]
That is, as apparent from FIG. 4, the temperature t at the tip of the injection nozzle 21 fluctuates with a large fluctuation width Δt in synchronization with the molding cycle, and the fluctuation width Δt1 of the temperatures t1 to t4 as it goes to the rear end side. , .DELTA.t2, .DELTA.t3, .DELTA.t4 decrease in order, but all fluctuate except for the measured value t5 of the temperature sensor P5 at the end.
Therefore, in the conventional injection nozzle temperature control system that controls the heating of the injection nozzle by associating the heater mounted on the injection nozzle with the temperature sensor on a one-to-one basis, the temperature of the injection nozzle does not vary depending on the molding cycle. There is a problem that cannot be adjusted properly.
[0006]
The present invention has been made in view of the above circumstances, and the temperature gradient in the axial direction of the injection nozzle can be adjusted appropriately without changing the position of the temperature sensor, and the temperature is suitable for the resin material. Nozzle temperature control of an injection molding machine that can be molded at a gradient heating temperature, and the heating temperature does not fluctuate in synchronization with the cycle of the molding cycle, and the injection nozzle can be heated to a stable temperature. It is an object to provide a method and a nozzle temperature control device.
[0007]
[Means for Solving the Problems]
The present invention is characterized by the following points in order to solve the above problems.
That is, in the nozzle temperature control method for an injection molding machine according to claim 1, the injection nozzle provided at the tip of the heating cylinder is provided with n heaters along the axial direction, and the injection nozzle heated by each heater. In the nozzle temperature control method for an injection molding machine in which n + 1 temperature sensors for detecting the temperature of the heater are provided and the heating temperature of the heater is controlled based on the temperature detected by the temperature sensor, each heater is connected to the injection nozzle on its axis. Weighted by variably setting each weighting factor to the temperature detected by two temperature sensors that are attached to each of one or more heating zones divided along the direction and arranged on both sides of the heating zone The heating temperature of each heater is individually controlled by the temperature controller based on the virtual temperature obtained by performing the above .
[0008]
In the nozzle temperature control method, during the molding operation, the injection nozzle is heated by n heaters, and the heating temperature is detected by two temperature sensors on both sides of each heating zone . The temperature detected by each temperature sensor is weighted to obtain a virtual temperature for temperature control for each of the heaters, and the temperature controller individually controls the heating temperature of each heater based on this virtual temperature. Appropriate virtual temperature can be obtained by appropriately setting the weighting for the temperature detected by each temperature sensor, and each heater can be heated and controlled so that the temperature gradient of the heating temperature along the axial direction of the injection nozzle is in a suitable state. Can do.
In addition, since each weighting factor for weighting is variably set, by changing the weighting factor as appropriate, each virtual temperature can be changed and the heating temperature of each heater can be adjusted accordingly. Corresponding to the resin material or the like used in the above, heating control is performed with a smooth temperature gradient having an appropriate temperature difference in the axial direction of the injection nozzle.
[0009]
Nozzle temperature controller of the injection molding machine according to claim 2, a heater mounted on each of the one or more heating zones partitioned along its axial direction in the injection nozzle, position on both sides of each heating zone A temperature sensor that is mounted on the injection nozzle and detects the heating temperature thereof, and a weight setting device that is provided corresponding to each heating zone and sets a weighting factor for the detected temperature of each temperature sensor belonging to each heating zone; A computing unit that is provided corresponding to each heating zone, calculates a virtual temperature corresponding to each heating zone by weighting the detected temperature of each temperature sensor based on a weighting factor set in the weight setting unit, and have a temperature controller for controlling the heating temperature of the heater belonging to each of the heating zones based on the provided corresponding to the heating zone wherein the arithmetic unit is determined virtual temperature, said heavy The setting device can variably set each weighting coefficient. When the heating zone is divided into a plurality of portions in the axial direction of the injection nozzle, the heating of the injection nozzle in the heating zones adjacent to each other is performed. The temperature sensor for detecting the temperature is characterized in that the temperature sensors located on the adjacent heating zone side are also used as one adjacent temperature sensor belonging to any one heating zone .
[0010]
In this nozzle temperature control device, the temperature detected by each temperature sensor on both sides of each heating zone is input to a computing unit corresponding to each heating zone, and based on the weighting factor set in the weight setting unit in each computing unit. An operation for weighting the detected temperature is performed to obtain a virtual temperature for each heating zone. Based on these virtual temperatures, a temperature controller corresponding to each heating zone controls the heating temperature of the heater belonging to each heating zone. According to this nozzle temperature control device, an apparent temperature (virtual temperature) in each heating zone that is not actually measured is detected, and each temperature controller is in the axial direction of the injection nozzle from the virtual temperature. The control value of the heating temperature of each heating zone can be set appropriately, so that the heating temperature of each heater is accurately controlled and the heating temperature does not fluctuate in synchronization with the cycle of the molding cycle. Control can be performed.
Moreover, by appropriately changing the weighting coefficient in each weight setting device, it is possible to change each virtual temperature and appropriately adjust the heating temperature of the heater in each heating zone. Correspondingly, heating control with a smooth temperature gradient having an appropriate temperature difference in the axial direction of the injection nozzle is performed.
Moreover, since two temperature sensors located on the side of the heating zone adjacent to each other are also used as one temperature sensor, the number of temperature sensors can be reduced, the structure is simplified, the probability of failure is reduced, and maintenance is performed. Inspection is also easier.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a nozzle temperature control device of an injection molding machine according to the present invention will be described with reference to the accompanying drawings.
In FIG. 1, reference numeral 1 denotes a heating cylinder of an injection device in an injection molding machine. A heater 1a is mounted on the outer periphery, and an injection screw 2 is rotatable in the circumferential direction and axially in an inner shaft hole 1b. Inserted to move forward and backward. An injection nozzle 3 having a resin passage 3 a communicating with the shaft hole 1 b of the heating cylinder 1 is coupled to the tip of the heating cylinder 1. In the first and second heating zones H1 and H2, which are divided into two in the axial direction on the outer peripheral portion of the injection nozzle 3, first and second heaters 4 and 5 whose heating temperatures are individually controlled, respectively. Is installed, and power is supplied from the power source E via the wiring 6.
[0014]
Reference numeral 7 denotes a temperature sensor attached to the injection nozzle 3 on both sides of each of the heating zones H1 and H2, and a first temperature sensor 7a on the front end side, a second temperature sensor 7b on the center side, and a rear end side. The third temperature sensor 7c is arranged with an interval in the axial direction of the injection nozzle 3.
8 and 9 correspond to the heating zones H1 and H2 in order to calculate the virtual temperatures PV1 and PV2 in the heating zones H1 and H2 used to control the heating temperatures of the heaters 4 and 5, respectively. First and second arithmetic circuits (arithmetic units) are provided, and the first arithmetic circuit 8 is connected to the first and second temperature sensors 7a and 7b belonging to the first heating zone H1. The detected temperatures T1 and T2 by them are inputted, and the second arithmetic circuit 9 is connected to the second and third temperature sensors 7b and 7c belonging to the second heating zone H2, and the detected temperatures by them are connected. T3 and T4 are input.
[0015]
Further, wherein the first arithmetic circuit 8 shows the first and second temperature sensors 7a, against the respective detection temperatures T1, T2 by 7b, whether the degree handled with priority to one of the detected temperature numerically weight coefficient (weight) a, a weight setter 10 for setting the B is connected, wherein the second arithmetic circuit 9, second, third temperature sensor 7b, Shi pairs each detected temperature T3, T4 by 7c A weight setting unit 11 is connected to set weighting coefficients (weights) C and D, which indicate numerically the degree of which detected temperature is handled with priority . The size of the weighting coefficient of each weight setting unit 10 and 11 can be changed and set as appropriate. The weighting factors A and B are in a certain relationship (A + B = 1) that is automatically determined when one of them is set, and the weighting factors C and D are in a similar relationship (C + D = 1).
[0016]
The numerals 12 and 13 are connected to the heaters 4 and 5 through first and second switches 14 and 15, respectively, and are provided corresponding to the heating zones H1 and H2, respectively. 1 and second temperature controllers, and the first and second temperature controllers 12 and 13 are connected to and input from the first and second arithmetic circuits 8 and 9, respectively. The heating temperatures of the heaters 4 and 5 are controlled based on the virtual temperatures PV1 and PV2.
[0017]
Next, the nozzle temperature control method will be described together with the operation of the nozzle temperature control device of the injection molding machine configured as described above.
During the molding operation by the injection molding machine, the switches 14 and 15 are closed and the injection nozzle 3 is heated by the heaters 4 and 5, and the temperatures T1, T2 and T3 on both sides in the heating zones H1 and H2 of the injection nozzle 3 are heated. , T4 are detected by the temperature sensors 7a, 7b, 7c and input to the first and second arithmetic circuits 8, 9, respectively.
[0018]
In the first and second arithmetic circuits 8 and 9, the first and second weight setting units 10 and 11 are applied to the detected temperatures T1, T2, T3, and T4 input from the temperature sensors 7a, 7b, and 7c. Is calculated by adding weighting factors (weights) A, B, C, and D to the detected temperatures T1, T2, T3, and T4 of the temperature sensors set to, and obtained by adding the weighting factors. The obtained virtual temperatures PV1 and PV2 are input to the temperature controllers 12 and 13, respectively. The temperature controllers 12 and 13 are supplied to the heaters 4 and 5 based on the deviation between the target temperatures set in advance for the heating zones H1 and H2 and the input virtual temperatures PV1 and PV2, respectively. The temperature of the injection nozzle 3 is controlled by adjusting the amount of electric power.
The calculation (weighting) for obtaining the virtual temperatures PV1 and PC2 by adding weighting coefficients in the first and second arithmetic circuits 8 and 9 is performed by the following equation.
[0019]
[Expression 1]

[0020]
As described above, the temperatures (T1, T2) and (T3, T4) detected by the temperature sensors (7a, 7b), (7b, 7c) on both sides belonging to the heating zones H1, H2 are weighted. When the virtual temperatures PV1 and PV2 are obtained and the temperatures of the heaters 4 and 5 are controlled by the temperature controllers 12 and 13 based on the virtual temperatures PV1 and PV2, the heating zones H1 and H2 are not actually measured. The apparent temperature (virtual temperature) is detected, and each temperature controller 12, 13 can appropriately set the control value of the heating temperature for each heating zone in the axial direction of the injection nozzle from the virtual temperature. Thereby, control of the heating temperature of each heater 4 and 5 is performed appropriately. Moreover, by changing the weighting factors A, B, C, and D in the weight setting units 10 and 11 as appropriate, the virtual temperatures PV1 and PV2 are changed, and the heaters 4 and 5 in the heating zones H1 and H2 are changed. Since the heating temperature can be adjusted, it is possible to perform heating control with a smooth temperature gradient having an appropriate temperature difference in the axial direction of the injection nozzle 3 corresponding to the resin material used for molding, and a molding cycle. It is possible to control the heating temperature that does not vary in synchronization with the period.
[0021]
According to the nozzle temperature control apparatus of the above-described embodiment, the virtual temperatures PV1 and PV2 change by changing the weighting factors by the weight setting units 10 and 11, depending on the magnitudes of the weighting factors A to D. One of the temperature sensors 7a and 7b in the first heating zone H1 or one of the temperature sensors 7b and 7c in the second heating zone H2 is installed with its position moved in the axial direction of the injection nozzle 3, respectively. Since the temperature sensor is operated as if the temperature corresponding to the virtual temperatures PV1 and PV2 was detected by the relocated temperature sensor, the first temperature sensor provided on the front end side of the first heating zone H1 of the injection nozzle 3 is used. Compared with the case where the heating temperature of the first heater 4 is controlled based on the temperature detected by the temperature sensor 7a, the variation in the heating temperature is eliminated without much influence from the mold temperature. Door can be.
[0022]
That is, it is almost impossible to change the positions of the temperature sensors 7a, 7b, and 7c every time the molded product changes. However, in the nozzle temperature control device of the present embodiment, the weight coefficients A to D are set as weights. The position of one temperature sensor (virtual temperature sensor) provided corresponding to each of the heating zones is changed (changed) appropriately in the axial direction of the injection nozzle by changing with the vessels 10 and 11. The same effect can be obtained, the influence of the mold temperature is small, and a stable heating temperature of the injection nozzle 3 can be set.
[0023]
Incidentally, FIG. 2 shows each temperature measurement position S in the axial direction of the injection nozzle 3 when the injection nozzle 3 is heated and controlled by the nozzle temperature control device of the above embodiment to change the weighting coefficient. It is the diagram which measured the temperature in S1, S2, S3, S4, and S5, and showed the temperature gradient.
The resin material used is polyethylene, and the set values of the target heating temperatures for the heaters 4 and 5 in the temperature controllers 12 and 13 are 210 ° C. and 230 ° C., respectively (in the case f, 225 ° C. and 230 ° C., respectively). ° C) . In addition, the weighting factor in each of the weight setting devices 10 and 11 is
In case a, A = 0, B = 1, C = 1, D = 0
In case b, A = 0.25, B = 0.75, C = 1, D = 0
In case c, A = 0.5, B = 0.5, C = 1, D = 0
In case d, A = 0.75, B = 0.25, C = 1, D = 0
In case e, A = 1, B = 0, C = 1, D = 0
In case f, A = 1, B = 0, C = 1, D = 0
[0024]
According to FIG. 2, the set values of the weighting factors C and D for the detected temperatures of the temperature sensors 7b and 7c in the second heating zone H2 are fixed to predetermined values (C = 1, D = 0), When the set values of the weighting factors A and B for the detected temperatures of the temperature sensors 7a and 7b in one heating zone H1 are changed, the temperature measurement position S5 on the rearmost end side of the injection nozzle 3 is constant regardless of the set values. The temperature gradient gradually decreases smoothly toward the temperature measurement position S on the foremost end side of the injection nozzle 3 in the order of the temperature measurement positions S4, S3, S2, and S1. It has been found that the degree of becomes steeper as the weighting factor A becomes larger (the weighting factor B becomes smaller). From this, in particular, by changing and setting the weighting factor for the detected temperature of the temperature sensors 7a, 7b belonging to the heating zone on the tip side of the injection nozzle 3 according to the type of resin material, temperature characteristics, etc., the injection nozzle 3 It was revealed that a temperature gradient in the axial direction of the film can be appropriately formed and stable molding can be performed.
[0025]
In the embodiment, the second temperature sensor 7b attached to the center of the injection nozzle 3 sets the temperature T2 on the rear side (adjacent second heating zone H2 side) in the first heating zone H1. Since it is used as both the temperature sensor to detect and the temperature sensor to detect the temperature T3 on the front side (the adjacent first heating zone H1 side) in the second heating zone H2, it is preferable because the number of temperature sensors can be saved. However, the temperatures T2 and T3 may be detected by a temperature sensor provided independently without being shared. Two temperature sensors provided at positions close to the axial direction of the injection nozzle 3 can be substantially regarded as one temperature sensor.
[0026]
In the above embodiment, the first and second heaters 4 and 5 are mounted in the first and second heating zones H1 and H2 that are divided into two in the axial direction of the injection nozzle 3, respectively. Although it comprised, the number of the heating zone of the injection nozzle 3 and the heater provided corresponding to it is not restricted to two, According to the magnitude | size of an injection nozzle, the number of one or three or more may be sufficient, n (n is a positive integer) can be provided.
Then, for n heating zones (heaters), the temperature sensor (n + 1) pieces is provided, it causes also serves for a temperature sensor provided between the heating zone adjacent to each other in the heating zone, the arithmetic circuit, the weight It is also possible to provide n controllers including a setting device, a temperature controller, and a switch, and individually adjust the heating temperature of the heater provided corresponding to each heating zone by the controller.
[0027]
Moreover, in the said embodiment, although the heaters 4 and 5 are each provided in each heating zone H1 and H2 divided in the axial direction of the injection nozzle 3, not only this but one or both A plurality of heaters are provided in each heating zone, and a plurality of heaters belong to each heating zone based on the virtual temperature obtained for each heating zone based on the temperature detected by the temperature sensor provided near both sides of each heating zone. The temperature of the heater may be controlled.
[0028]
In the embodiment, the first and second weight setting units 10 and 11 for setting the weighting coefficient are connected to the first and second arithmetic circuits 8 and 9 as individual devices, respectively. Although it is configured, the present invention is not limited to this, and those having the same function as the weight setting units 10 and 11 may be incorporated in the first and second arithmetic circuits 8 and 9. Furthermore, although the weighting factors A, B, C, and D are set by the relational expressions of A + B = 1 and C + D = 1 in the weight setting units 10 and 11, the present invention is not limited to this and is set by other relational expressions. Alternatively, each may be set individually.
[0029]
【The invention's effect】
As described above, according to the present invention, the following excellent effects are obtained. According to the nozzle temperature control method of the injection molding machine according to claim 1, the heating temperature of the injection nozzle detected by the two temperature sensors on both sides of each heater is weighted by variably setting the weighting coefficient , A virtual temperature for temperature control for each heater is obtained, and the temperature controller individually controls the heating temperature of each heater based on this virtual temperature. Therefore, the temperature detected by each temperature sensor can be changed appropriately. Appropriate virtual temperatures can be obtained by appropriately setting the weights for and the heaters can be heated and controlled so that the temperature gradient of the heating temperature along the axial direction of the injection nozzle is in a suitable state.
In addition, by changing the weighting factor as appropriate, the virtual temperature can be changed and the heating temperature of the heater in each heating zone can be adjusted accordingly. It is possible to easily perform heating control with a smooth temperature gradient having an appropriate temperature difference in the axial direction.
[0030]
According to the nozzle temperature control device of an injection molding machine according to claim 2, a state in which an apparent temperature (virtual temperature) in each heating zone that is not actually measured by weighting the temperature detected by the temperature sensor is detected. In each temperature controller, since the control value of the heating temperature of each heating zone in the axial direction of the injection nozzle can be appropriately set from the virtual temperature, the heating temperature of the heater in each heating zone Can be accurately controlled, the temperature gradient in the axial direction of the injection nozzle can be set appropriately, and the heating temperature can be reliably controlled without fluctuation in synchronization with the cycle of the molding cycle. .
Moreover, by appropriately changing the weighting coefficient in each weight setting device, each virtual temperature can be changed and the heating temperature of the heater in each heating zone can be adjusted appropriately, so that the resin material used for molding can be used. Correspondingly, heating control with a smooth temperature gradient having an appropriate temperature difference in the axial direction of the injection nozzle can be easily performed.
In addition, since two temperature sensors located on the adjacent heating zones are also used as one temperature sensor, the number of temperature sensors can be reduced, the structure is simplified, the probability of failure is reduced, and maintenance is performed. Inspection can also be performed easily.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a nozzle temperature control device of an injection molding machine according to the present invention.
FIG. 2 is a diagram showing the temperature gradient in the axial direction of the injection nozzle in an example in which the injection nozzle is heated and controlled by changing the weighting coefficient by the control device.
FIG. 3 is an explanatory diagram showing a state of temperature measurement of an injection nozzle when an injection nozzle is heated and controlled by a conventional nozzle temperature control device.
FIG. 4 is a diagram showing the state of temperature fluctuation at each measurement point of the injection nozzle obtained by the same temperature measurement.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heating cylinder 2 Injection screw 3 Injection nozzle 4, 5 Heater 7, 7a, 7b, 7c Temperature sensor 8, 9 Arithmetic circuit (controller)
10, 11 Weight setter 12, 13 Temperature controller 14, 15 Switch H1, H2 Heating zone

Claims (2)

An n number of heaters are provided along the axial direction of the injection nozzle projecting from the tip of the heating cylinder, and n + 1 temperature sensors are provided for detecting the temperature of the injection nozzle heated by each heater. In the nozzle temperature control method of an injection molding machine that controls the heating temperature of the heater based on the temperature that is made
Each of the heaters is attached to each of one or a plurality of heating zones divided along the axial direction of the injection nozzle, and the temperature detected by two temperature sensors arranged on both sides of the heating zone is set. A nozzle temperature control method for an injection molding machine, wherein the heating temperature of each heater is individually controlled by a temperature controller based on a virtual temperature obtained by performing weighting by variably setting each weighting factor . A heater mounted in each of the one or more heating zones partitioned along its axial direction in the injection nozzle, the temperature to detect the heating temperature is attached to the injection nozzle in position on both sides of each heating zone A sensor, a weight setter that sets a weighting factor for the temperature detected by each temperature sensor that belongs to each heating zone, and a temperature sensor that is provided for each heating zone. A calculator that calculates a virtual temperature corresponding to each heating zone by weighting the temperature based on a weighting factor set in the weight setting unit, and a virtual unit provided corresponding to each heating zone and calculated by the calculator comprise a temperature controller for controlling the heating temperature of the heater belonging to each of the heating zones based on the temperature, the weight setter can each weighting factor is variably set It has become,
When the heating zone is divided into a plurality in the axial direction of the injection nozzle, the temperature sensors for detecting the heating temperature of the injection nozzle in the heating zones adjacent to each other are temperature sensors located on the adjacent heating zone side. However, the nozzle temperature control device for an injection molding machine is also used as one adjacent temperature sensor belonging to one of the heating zones .

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