JPH10235704A - Method and apparatus for estimating pressure in mold in injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate the pressure of a molten material in a cavity in a packing stage without the need of processing and expense for measuring the pressure in a mold in an injection molding. SOLUTION: The driving pressure Ph of an injection screw 3 which was detected when a molten material is injected with a molding mold opened in advance or with an injection nozzle separated from the mold is stored, and the pressure in the mold during normal packing operation is estimated in real time on the basis of the difference between the driving pressure Ph of the injection screw which was detected in real time while the molten material being injected in a normal packing condition with the molding mold closed and the driving pressure Ph of the injection screw which was stored in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for estimating an internal pressure of a molding die in an injection molding machine.

[0002]

2. Description of the Related Art FIG. 22 is a view showing a schematic configuration of a general injection molding machine and its control device.
Has a barrel 2, an injection screw 3 rotatably and forwardly and backwardly provided in the barrel 2, and an injection cylinder device 4 for driving the injection screw 3 forward and backward. By moving the injection screw 3 forward, the molten resin in the barrel 2 is injected and filled into the cavity 8 of the molding die 7 via the nozzle 5 and the gate 6.

The operation of the injection cylinder device 4 is controlled by a hydraulic unit 10 to which a control command is given from a control device 9 by a microcomputer. That is, the injection cylinder device 4 is controlled by the hydraulic unit 10.
Of the injection screw 3 operated by the injection cylinder device 4 and the movement speed (injection speed) of the injection screw 3 are controlled.

In order to obtain a high quality molded product, the control unit 9
The position information of the injection screw 3 detected by the screw position detector 11 and the resin pressure information in the cavity detected by the cavity resin pressure sensor 12 incorporated in the molding die are input to the screw position during the filling process. The deviation between the pre-set resin pressure in the cavity and the actual resin pressure in the cavity detected by the cavity resin pressure sensor 12 is fed back to the injection speed control system, and the filling speed is controlled. There is an injection molding machine having a function of controlling a resin pressure to a set value.

As described above, in the injection speed control method for controlling the injection filling speed so that the resin pressure in the cavity is maintained at a set value using the resin pressure in the cavity as a feedback amount, the injection speed is controlled according to the screw position during the filling process. When the detected value of the resin pressure in the cavity is higher than the resin pressure in the cavity set in advance, the filling speed is automatically reduced. As a result, an excessive increase in the resin pressure in the cavity can be suppressed, and the size and weight of the mold can be reduced, the size of the molding machine can be reduced, and the quality of the molded product can be improved.

[0006]

However, in the conventional apparatus as described above, it is necessary to attach a resin pressure sensor to a molding die in order to detect the internal pressure of the die. However, in practice, it is costly to perform processing for attaching the resin pressure sensor to all of the molding dies for which it is desired to detect the internal pressure of the mold. May not be provided. In addition, it is often difficult to attach a resin pressure sensor by partially processing an existing molding die.

[0007] Further, in terms of the setup work for exchanging the molding die, it is necessary to attach and detach the resin pressure sensor and its wiring every time the molding die is attached to and detached from the molding machine, which increases the working time.

In view of the above, the present invention eliminates the need for labor and expense for machining a molding die for measuring the internal pressure of the molding die, and does not complicate the setup work for exchanging the molding die. It is an object of the present invention to provide a method and an apparatus for estimating an in-mold pressure capable of estimating a resin pressure in a cavity at a filling stage.

[0009]

According to a first aspect of the present invention, there is provided an injection molding machine for molding a required molded product by injecting a molten material into a molding die cavity by moving an injection screw.
The driving pressure value of the injection screw detected when the molten material is injected in a state where the injection nozzle is separated from the molding die or the molding die is opened is stored in advance, and the molding die is closed. Based on the difference between the driving pressure value of the injection screw detected in real time while injecting the molten material in the normal filling state and the driving pressure value of the injection screw stored in advance, the mold inner pressure during the normal filling operation is It is characterized in that estimation is performed in real time.

[0010] The second invention provides an injection speed and an injection speed by a movement of an injection screw which are detected when a molten material is injected in a state where an injection nozzle is separated from a molding die or in a state where the molding die is opened. The injection acceleration is stored, and based on the difference between the injection speed and the injection acceleration detected in real time while injecting the molten material in the normal filling state and the previously stored injection speed and the injection acceleration, the first
The invention is characterized in that the in-mold pressure estimated value at the time of the normal filling operation estimated in the invention is corrected.

According to a third aspect of the present invention, there is provided a driving pressure, an injection speed, and a driving speed of an injection screw which are detected when a molten material is injected in a state where an injection nozzle is separated from a molding die or the molding die is opened. The injection molding machine and the model parameters of the molten material are identified using the injection acceleration, and the driving pressure, the injection speed and the driving speed of the injection screw detected in real time while injecting the molten material in the normal filling state with the molding die closed. The in-mold pressure during normal filling operation is estimated based on the injection acceleration and the identified model parameters.

According to a fourth aspect of the present invention, the structure and parameters of a mold internal pressure estimation function are determined in advance by an operator's input from a molding die information database, a molten material information database, and an injection molding machine information database. Using the operation data when the molten material was injected with the injection nozzle separated from the mold or with the molding die opened, the structure and parameters of the above-mentioned mold internal pressure estimation function were modified and melted in the normal filling state The mold internal pressure is estimated by giving the estimated value of the mold internal pressure when the material is injected and the operating data detected in real time while injecting the molten material in the normal filling state with the molding die closed to the mold internal pressure estimation function. It is characterized by the following.

According to a fifth aspect of the present invention, there is provided an apparatus for estimating a driving pressure of an injection screw in an injection molding machine for injecting a molten material into a molding die cavity by moving an injection screw to form a required molded product. Driving pressure detecting means for storing the driving pressure of the injection screw detected by the driving pressure detecting means when the molten material is injected while the injection nozzle is separated from the molding die or the molding die is opened. And a drive pressure of the injection screw detected in real time by the drive pressure detection means while injecting the molten material in a normally filled state with the molding die closed, and a drive pressure stored in the storage device. And a calculating device for estimating the in-mold pressure at the time of injecting the molten material in the normal filling state in real time based on the difference between the two.

According to a sixth aspect of the present invention, there is provided an injection speed detecting means for detecting an injection speed due to the movement of the injection screw, an injection acceleration detecting means for detecting an injection acceleration due to the movement of the injection screw, and a state in which the injection nozzle is separated from the molding die. A storage device for storing the injection speed and the injection acceleration detected by the injection speed detection means and the injection acceleration detection means when the molten material is injected with the molding die opened; While injecting the molten material in the filled state, based on the difference between the injection speed and the injection acceleration detected in real time by the injection speed detection means and the injection acceleration detection means and the injection speed and the injection acceleration stored in the storage device. And an arithmetic unit for correcting the estimated value of the in-mold pressure based on the driving pressure.

In a seventh aspect, a driving pressure detecting means for detecting a driving pressure of an injection screw, an injection speed detecting means for detecting an injection speed by movement of the injection screw,
Injection acceleration detection means for detecting the injection acceleration due to the movement of the injection screw, and when the molten material is injected in a state where the injection nozzle is separated from the molding die or the molding die is opened, the driving pressure detection means, Injection speed detecting means, and a driving pressure of the injection screw detected by the injection acceleration detecting means, an injection speed, and a computing device for identifying the model parameters of the molten material using the injection acceleration,
Based on the driving pressure, the injection speed and the injection acceleration of the injection screw detected in real time by the driving pressure detecting means, the injection speed detecting means and the injection acceleration detecting means at the time of the normal filling operation, and the normal filling state. And an arithmetic unit for estimating the in-mold pressure when the molten material is injected in real time.

Further, the eighth invention provides a molding die information database, a molten material information database, an injection molding machine information database, the molding die information database,
An input device and an arithmetic unit for determining an in-mold pressure estimation function based on an operator's input from a molten material information database and an injection molding machine information database; a detecting means for detecting operation data when the molten material is injected; An arithmetic unit that corrects the structure and parameters of the mold internal pressure estimation function using operation data when the molten material is injected with the injection nozzle separated from the mold or with the molding die opened,
The mold pressure at an arbitrary point in the molding die is estimated in real time by giving the mold pressure estimation value when the molten material is injected in the regular filling state and the operation data at the time of regular filling operation to the mold pressure estimation function. And an arithmetic unit.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Note that FIG.
The same parts as those described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

The injection screw 3 is provided with a screw position detector 11.
The position signal detected at 1 is input to the arithmetic and control unit 13. The injection cylinder device 4 is provided with an injection oil pressure sensor 14.
The oil pressure signal detected at is also input to the arithmetic and control unit 13.

By the way, the arithmetic and control unit 13 is configured as shown in FIG.
As shown in (a) of FIG.
When the molten material is injected while the molding die 7 is open as shown in FIG.
And a memory for storing the driving pressure of the injection screw 3 detected in the step (1). When the molten resin (molten material) is injected in the normal filling state in which the molding die 7 is closed and the injection nozzle 5 is connected, the driving pressure of the injection screw 3 is detected in real time by the injection oil pressure sensor 14, and the detection is performed. The driving pressure is compared with the driving pressure stored in the memory, a gain calculation is performed based on the difference, and the molten material is injected with the injection nozzle tip (molding mold inlet) or the molding mold opened. Then, the mold pressure when the molten resin is injected in the normal filling state at the point where the mold is opened to the atmosphere is estimated in real time.

That is, the relationship between the injection cylinder, the injection screw, the barrel, and the molding die in the filling step of the injection molding machine can be represented by a model shown in FIG.

The equations of motion of the injection cylinder and the injection screw can be expressed by equations (1) and (2) for the normal filling state and the state in which the injection nozzle is separated from the molding die, respectively.

[0022]

(Equation 4) Here, the sectional area of the injection cylinder is Ah, and the sectional area of the barrel is A
b, the injection cylinder drive pressure is Ph, the resin pressure in the barrel is Pb, and the mass of the part that moves with the injection screw is M,
The displacement of the injection screw is x, the viscous drag coefficient between the injection screw and the barrel inner wall is B, and Ph at the time of regular filling,
Ph , P , Pb, x, the state where the nozzle is separated from the molding die
b and x . Expression (3) is obtained by rearranging the expressions (1) and (2).

[0023]

(Equation 5) Here, it is assumed that the injection screw performs the same movement even when the molten material is injected in the normal filling state or when the molten material is injected with the nozzle separated from the molding die. That is, x =
Assuming x , equation (3) can be simplified as equation (4).

[0024]

(Equation 6) In the filling process, the molten material is barrel → nozzle → sprue →
It flows along the route of runner → gate → cavity. The cross section of the flow path of the barrel, the nozzle, the sprue, the runner, and the gate portion can be approximated to a circle (rectangular, trapezoidal, etc. are replaced with circles of equivalent diameter). The relationship between the shear stress and the shear rate of the molten material follows a power law, and the flow in the barrel and nozzle is H
Assuming that the flow is an ele-Shaw flow, the section pressure loss ΔP when the molten material having the non-Newtonian flow characteristic passes can be expressed by equation (5).

[0025]

(Equation 7) Here, η is the viscosity coefficient of the molten material, L is the section length of a circular pipe flow path with an equivalent diameter, R is the equivalent diameter, and n is a constant specific to the resin. Under these assumptions, the resin pressure Pn, Pn at the nozzle tip at the time of regular filling or when the nozzle is separated from the molding die is

[0026]

(Equation 8) Here, assuming that the resin flow in the barrel and the nozzle during injection of the molten material is the same between the normal filling state and the state in which the nozzle is separated from the molding die, since x = x, the expression (8) becomes (9) ) Can be simplified as

Pn − Pn = Pb − Pb (9) At the time of injection with the nozzle separated from the molding die, the tip of the nozzle is open to the atmosphere. That is, since it is considered that Pn = 0, the relationship represented by the expression (10) is derived from the expressions (4) and (9).

[0028]

(Equation 9) Equation (10) indicates that the screw motion and the flow of the molten material are different between the injection of the molten material in the normal filling state with the molding die closed and the injection of the molten material with the nozzle separated from the molding die. Under the assumption that they are the same, an appropriate gain Ah / Ab is applied to the difference between the driving pressure Ph of the injection cylinder in the normal filling state and the driving pressure Ph of the injection cylinder in a state where the nozzle is separated from the forming die. This indicates that the pressure is equal to the molten material pressure (internal pressure in the mold) at the nozzle tip (mold entrance) when the molten material is injected in the normal filling state.

Similarly, the screw motion and the flow of the molten material are the same between the time of injection of the molten material in the normal filling state with the molding die closed and the time of the injection of the molten material with the molding die opened. Under the assumption that the difference between the injection cylinder driving pressure Ph in the normal filling state and the injection cylinder driving pressure Ph ′ in the state in which the molding die is opened, an appropriate gain Ah / Ab is applied. The molten material pressure (mold pressure) P at the time of injection of the molten material in the normal filling state at the point where the molten material is released to the atmosphere when the molten material is injected with the molding die opened.
It turns out that it is equal to i.

FIG. 4 shows the procedure of the method for estimating the mold inner pressure.

Incidentally, the sampling period is 0.005 s.
The in-mold pressure was estimated offline using the injection screw driving pressure and the injection cylinder position data collected in ec, and the estimated value was evaluated using the in-mold pressure data measured by the resin pressure sensor provided in the molding die.

FIG. 5 shows the driving pressure of the injection screw when the molten resin is injected with the molding die open, and FIG. 6 shows the driving pressure of the molten resin with the molding die closed in the normal filling state. Shows the driving pressure of the injection screw. FIG. 7 shows the difference between the driving pressures of the injection cylinders shown in FIGS. 5 and 6, and FIG. 8 shows the case where the molding die is opened to the atmosphere using the difference between the driving pressures shown in FIG. It is a figure which shows the result of having estimated the mold internal pressure at the time of regular filling at a certain point.

On the other hand, FIG. 9 is a view showing the result of measuring the internal pressure of the mold at a certain point in the molding mold at the time of regular filling using a resin pressure sensor.

However, comparing FIG. 8 with FIG.
It can be seen that the in-mold pressure estimation value in the first invention is close to the measurement result shown in FIG.

In the above method for estimating the internal pressure of the mold, the injection screw is driven when the molten material is injected in a state where the nozzle is separated from the molding die or when the molding die is opened and when the molten material is injected in the normal filling state. Although it was assumed that the motion and the flow of the molten material were the same, the screw motion is actually different due to load fluctuation during filling and lack of reproducibility of the injection cylinder drive system. In particular, when the melt front of the molten material reaches the gate and the viscous resistance due to the flow of the molten material increases, the motion of the injection screw greatly shifts.

Therefore, the molten material was injected with the injection speed and the injection acceleration by the movement of the injection screw when the molten material was injected with the nozzle separated from the molding die or with the forming die opened, and in the normal filling state. Difference between the injection speed and the injection acceleration due to the movement of the injection screw at the time of (3)
As shown in the equation, by adding it as a correction term to the in-mold pressure estimated value, it is possible to reduce an estimation error due to a deviation in the motion of the injection screw.

That is, the displacement of the injection screw in the normal filling state is x, and the displacement of the injection screw in the state in which the injection nozzle is separated from the molding die or in the state where the molding fitting is opened is represented by x.
x or x '

[0038]

(Equation 10) Thus, the in-mold pressure estimation value can be estimated.

Detection of the injection speed and the injection acceleration by the movement of the injection screw can be detected by attaching a speed and acceleration sensor to a portion that moves together with the injection screw. It can also be obtained by performing a difference operation.

In making the above correction, the arithmetic and control unit 11
In addition to the above functions, a memory for storing the injection speed and the injection acceleration, and a calculation function for correcting the estimated value in the mold using the difference between the injection speed and the injection acceleration are added.

FIG. 10 shows a procedure of a method for estimating the in-mold pressure for correcting the injection speed or the like.

Thus, a result obtained by adding a correction based on the injection speed or the like due to the movement of the injection screw to the difference between the driving pressures is shown. That is, FIG. 11 shows the injection speed by the movement of the injection screw when the molten resin is injected with the molding die opened, and FIG. 12 shows the injection speed when the molten resin is injected in the normal filling state with the molding die closed. This shows the injection speed due to the movement of the injection screw. FIG. 13 shows the difference between the injection speeds shown in FIGS. 11 and 12. FIG. 14 shows an injection acceleration difference value obtained by adding a time difference calculation to the injection speed difference value shown in FIG.

FIG. 15 shows the result of correcting the driving pressure difference value using the injection speed difference value shown in FIG. 13 and the injection acceleration difference value shown in FIG. FIG. 16 shows an estimated value of the internal pressure of the mold at the time of normal filling at the point where the pressure becomes the atmospheric pressure in a state where the molding die is opened, estimated using the pressure difference value.

On the other hand, a model for estimating the mold internal pressure is constructed based on the equations (1), (2), (6) and (7), and the injection nozzle is separated from the molding die or the molding die is opened. In this state, the model parameters of the injection molding machine and the molten material are identified, and the mold at the point where the molten material is released to the atmosphere when the molten material is injected with the nozzle tip or its molding die open during normal filling operation The internal pressure can also be estimated.

That is, the molten material pressure at the point where the molten material is released to the atmosphere when the molten material is injected with the nozzle separated from the molding die or with the molding die opened is considered to be zero. Equation (11) or (12) is obtained from the relationship between the equation and equation (7).

[0046]

[Equation 11] Here, B , η , L , and R are the viscous drag coefficient between the injection screw and the barrel inner wall when the nozzle is separated from the molding die, the viscous coefficient of the molten material, and the section length of the circular pipe flow path of the equivalent diameter. B ', η ', L ', R ' are the viscous drag coefficient between the injection screw and the barrel inner wall with the molding die opened, the viscous coefficient of the molten material, and the circular pipe flow of the equivalent diameter. The section length of the road and the equivalent diameter.

Therefore, since M, Ah and Ab are determined by the injection molding machine, the melting is performed in the above-mentioned formula (11) or (12) with the nozzle separated from the molding die or with the molding die opened. Injection acceleration, injection speed, and injection cylinder drive pressure detected when material is injected

[0048]

(Equation 12) By substituting into equation (11) or (12),
Model parameters B of the injection molding machine and the molten material,
η , L , R or B ′, η ′, L ′, R ′ can be identified.

By transforming equations (1) and (6), equation (13) is obtained.

[0050]

(Equation 13) Therefore, in the above equation (13), the model parameters B , η , L , and the model parameters identified in the above equation (11) or (12) are expressed.
Substituting R or B ', η ', L ', R '
By substituting the injection acceleration, injection speed, and injection screw driving pressure at the time of regular filling, the molten material is injected at the tip of the nozzle when the molten material is injected in the regular filling state or the molten material with the molding die opened. The in-mold pressure Pi in the normal filling state at the point where the mold is opened to the atmosphere upon injection can be estimated by the following equation.

[0051]

[Equation 14] FIG. 17 shows the result of estimating the mold internal pressure at the time of normal filling at the point where the mold is opened to the atmosphere with the mold open, using the method through online model identification.

Further, the estimation of the internal pressure of the mold at an arbitrary point in the molding die is performed by estimating the internal pressure of the molding die from the point that the molten material is opened to the atmosphere when the molten material is injected with the entrance of the molding die or the molding die opened. Estimate the pressure loss up to any point of, from the mold internal pressure at the point of opening to the atmosphere when injecting the molten material with the molding die entrance or the molding die open estimated by the method described above, This can be done by subtracting the pressure loss estimate. FIG. 18 shows a block diagram of the pressure loss estimating device.

That is, in advance, data such as the injection cylinder diameter from the injection molding machine database, mold shape information from the molding die database, resin characteristics such as specific heat, latent heat, and viscosity of the resin from the resin characteristic database and operation input. The structure and parameters of the in-mold pressure estimation function are determined in advance by the pressure loss model structure and the parameter calculation device according to the sensor position, that is, the position at which the in-mold pressure is to be estimated.

Therefore, operation data when the molten material is injected with the injection nozzle separated from the molding die and with the molding die opened, that is, when the molten material is injected with the molding die opened. Using operation data such as the pressure difference between the point of opening to the atmosphere and the entrance of the molding die, etc., the structure and parameters of the previously determined mold pressure estimation function are corrected by the pressure loss model structure and parameter correction device. By adding the injection operation data in the normal filling state to this, the pressure loss value up to an arbitrary point in the molding die is estimated.

Thus, the above-mentioned pressure loss value is obtained from the internal pressure of the mold at the point where the mold is opened to the atmosphere when the molten material is injected with the mold inlet or the mold opened, as estimated by the equation (10) or the like. By subtraction, it is possible to estimate the mold internal pressure at any point in the molding die.

FIG. 19 shows an estimation of the internal pressure at a certain point in the molding die by combining the estimated value of the internal pressure and the estimated value of the pressure loss by the method for estimating the internal pressure of the first invention shown in FIG. It is a figure showing a result. FIG. 20 shows the result of estimating the mold internal pressure at a certain point in the molding die by combining the above-mentioned estimated value of the pressure loss and the estimated value of the mold internal pressure by the method for estimating the mold internal pressure of the second invention shown in FIG. FIG.
FIG. 1 shows a result of estimating an in-mold pressure at a certain point in a molding die by combining an in-mold pressure estimation value by the in-mold pressure estimation method of the third invention shown in FIG. 17 and the pressure loss estimation value.

FIGS. 19, 20, and 2
By comparing FIG. 1 with FIG. 9, it can be confirmed that the mold internal pressure estimation value by the internal pressure estimation method in the present invention maintains sufficient accuracy.

[0058]

As described above, according to the present invention, the driving pressure of the injection screw detected when the molten material is injected in a state where the molding die is opened or the injection nozzle is separated from the molding die in advance, Based on the injection speed, injection acceleration, and the injection pressure, injection speed, injection acceleration, etc. of the injection screw detected in real time while injecting the molten material in the normal filling state with the mold closed, the mold internal pressure during the regular filling operation is Since the estimation is performed in real time, there is no need to attach a resin pressure sensor to the molding die as in the past,
Without the labor and expense of processing for that,
Further, the pressure of the molten resin in the cavity of the molding die can be estimated without complicating the setup operation of the molding die exchange.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of an apparatus for estimating an in-mold pressure of an injection molding machine according to the present invention.

FIGS. 2A and 2B are explanatory views showing a state in which an injection nozzle is separated from a molding die and a state in which a molten material is injected in a state in which the molding die is opened.

FIG. 3 shows an injection cylinder, a screw, a barrel, a nozzle,
FIG. 3 is a model diagram showing a simplified model of a molding die.

FIG. 4 is an explanatory diagram showing a procedure of a method for estimating a mold inner pressure according to the first invention.

FIG. 5 is a diagram showing a driving pressure of an injection screw when a molten resin is injected with a molding die opened.

FIG. 6 is a diagram showing a driving pressure of an injection screw when a molten resin is injected in a regular filling state with a molding die closed.

FIG. 7 is a view showing a difference between driving pressures of the injection screws shown in FIGS. 5 and 6;

8 shows the result of estimating the mold internal pressure at the time of regular filling at the point where the mold is opened to the atmosphere with the mold open, using the difference in driving pressure of the injection screw shown in FIG. 7.

FIG. 9 is a view showing the result of measuring the mold internal pressure at a certain point in a molding mold at the time of regular filling using a resin pressure sensor.

FIG. 10 is an explanatory diagram showing a procedure of a mold pressure estimation method according to the second invention.

FIG. 11 is a diagram showing an injection speed due to movement of an injection screw when a molten resin is injected with a molding die opened.

FIG. 12 is a diagram showing an injection speed due to movement of an injection screw when a molten resin is injected in a regular filling state.

FIG. 13 is a diagram showing a difference between the injection speeds shown in FIGS. 11 and 12.

FIG. 14 shows the difference between the injection acceleration caused by the movement of the injection screw when the molten resin is injected in the normal filling state and the injection acceleration caused by the movement of the injection screw when the molten material is injected with the molding die opened. FIG.

FIG. 15 is a diagram illustrating a result obtained by correcting the driving pressure difference of the injection screw illustrated in FIG. 7 using the injection speed difference and the injection acceleration difference illustrated in FIGS. 13 and 14;

FIG. 16 is a view showing the result of estimating the internal pressure of the mold at the point where the mold is opened to the atmosphere when the mold is opened and normal filling is performed using the drive pressure difference shown in FIG. 15 when the mold is closed.

FIG. 17 is a diagram showing a result of estimating a mold internal pressure at the time of normal filling with the molding die closed at a point where the molding die is opened to the atmosphere with the molding die opened.

FIG. 18 is an explanatory diagram showing a method for estimating the pressure loss of the mold inner pressure.

FIG. 19 is a view showing the result of estimating the mold internal pressure at a certain point in the molding die at the time of normal filling using the mold internal pressure estimated value and the pressure loss estimated value shown in FIG. 8;

FIG. 20 is a diagram showing a result of estimating a mold inner pressure at a certain point of a molding die at the time of normal filling using the estimated mold pressure value and the estimated pressure loss value shown in FIG. 16;

FIG. 21 is a diagram showing a result of estimating a mold internal pressure at a certain point of a molding die at the time of normal filling using the mold internal pressure estimated value and the pressure loss estimated value shown in FIG. 20;

FIG. 22 is an explanatory diagram showing an injection control device of a conventional injection molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection molding machine 2 Barrel 3 Injection screw 4 Injection cylinder device 5 Nozzle 6 Gate 7 Mold 8 Mold cavity 10 Hydraulic unit 12 Screw position detector 13 Operation control device 14 Injection oil pressure

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Shigemasa 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center (72) Inventor Katsuyuki Suzuki 4-chome, Ginza, Chuo-ku, Tokyo No. 2-11 Toshiba Machine Co., Ltd. (72) Inventor Minoru Yamaguchi 2-1-1 Ginza, Chuo-ku, Tokyo Toshiba Machine Co., Ltd.

Claims (11)

[Claims] 1. An injection molding machine for injecting a molten material into a molding die cavity by moving an injection screw to form a desired molded product, wherein an injection nozzle is separated from the molding die or the molding die is previously set. The driving pressure value of the injection screw detected when the molten material is injected with the mold opened is stored, and the injection screw detected in real time while injecting the molten material in the normal filling state with the molding die closed. The internal pressure of the injection molding machine is estimated in real time based on the difference between the driving pressure value of the injection molding machine and the previously stored driving pressure value of the injection screw. Estimation method. 2. The injection cylinder cross-sectional area is Ah, the barrel cross-sectional area is Ab, and the injection cylinder driving pressure during regular filling is P.
h, the injection cylinder driving pressure in the state where the injection nozzle is separated from the molding die or the molding die is opened is Ph or P
h ′, where Pn or Pi ′ is the resin pressure at a point where the molten material is released to the atmosphere when the molten material is injected with the nozzle tip or the mold opened during the regular filling operation, Pn = Ah / Ab · ( The resin pressure at the tip of the nozzle or at the point of opening to the atmosphere during the regular filling operation is estimated in real time by Ph - Ph ) Pi '= Ah / Ab. ( Ph-Ph '). A method for estimating an in-mold pressure in the injection molding machine described in the above. 3. An injection speed and an injection acceleration by movement of an injection screw detected when a molten material is injected in a state where an injection nozzle is separated from a molding die or in a state where the molding die is opened, are stored in advance. Estimating the mold internal pressure in the normal filling state based on the difference between the injection speed and the injection acceleration detected in real time while injecting the molten material in the normal filling state and the previously stored injection speed and the injection acceleration. The method for estimating an in-mold pressure in an injection molding machine according to claim 1, wherein the value is corrected. 4. The barrel cross-sectional area is Ab, the mass of the portion moving with the injection screw is M, the viscous drag coefficient between the injection screw and the barrel inner wall is B, the displacement of the injection screw in the normal filling state is x, and the molding is x. When the displacement of the injection screw in a state where the injection nozzle is separated from the mold or in a state where the molding die is opened is x or x ′, 4. The method according to claim 3, wherein the estimated value of the in-mold pressure is corrected by the following method. 5. An injection molding machine for injecting a molten material into a molding die cavity by moving an injection screw to form a desired molded product, wherein an injection nozzle is previously separated from the molding die or a molding die is formed. The injection molding machine and model parameters of the molten material are identified using the driving pressure, the injection speed, and the injection acceleration of the injection screw detected when the molten material is injected with the mold opened, and the molding die is Driving pressure of the injection screw detected in real time while injecting the molten material in the closed normal filling state,
A method for estimating an in-mold pressure in an injection molding machine, comprising estimating an in-mold pressure during a normal filling operation based on an injection speed and an injection acceleration and the identified model parameters. 6. The injection cylinder has a cross-sectional area of Ah, a barrel cross-sectional area of Ab, a mass of a portion moving together with the injection screw, M, a viscosity resistance coefficient between the injection screw and the inner wall of the barrel, B, and a viscosity coefficient of a molten material, η. , The section length of the equivalent diameter circular pipe flow path is L, the equivalent diameter is R, the constant specific to the resin is n, and the injection screw is in a state where the injection nozzle is separated from the molding die or the molding die is opened. X or x ′,
When the driving pressure of the injection cylinder is Ph or Ph ', According to this, the model parameters B , η , L , R , or B ′ of the injection molding machine and the molten material in a state where the injection nozzle is separated from the molding die or the molding die is opened.
η ′, L ′, and R ′ are identified in advance, and when the displacement of the injection screw in the normal filling state is x and the driving pressure of the injection cylinder is Ph, The pressure inside the mold Pn or Pi at the point where the molten material is opened to the atmosphere when the molten material is injected with the tip of the nozzle or the former mold opened in the regular filling operation is estimated. A method for estimating an in-mold pressure in the injection molding machine described in the above. 7. The structure and parameters of an internal pressure estimation function are determined in advance by an operator's input from a molding die information database, a molten material information database, and an injection molding machine information database. The structure and parameters of the function for estimating the internal pressure of the mold are modified using operation data obtained when the molten material is injected in a state where the mold is released or the molding die is opened, and the molten material is filled in a normal filling state. By giving the estimated value of the inner pressure of the mold at the time of injection and operating data detected in real time while injecting the molten material in a normally filled state in which the molding die is closed to the above-mentioned inner pressure estimation function, any value in the molding die can be determined. The in-mold pressure at the point (1) is estimated.
A method for estimating an in-mold pressure in the injection molding machine described in the above. 8. A driving pressure for detecting a driving pressure of the injection screw in an in-mold pressure estimating apparatus for an injection molding machine for injecting a molten material into a molding die cavity by moving an injection screw to form a required molded product. Detecting means;
A storage device for storing the driving pressure of the injection screw detected by the driving pressure detecting means when the molten material is injected in a state where the injection nozzle is separated from the molding die or the molding die is opened, Based on the difference between the driving pressure of the injection screw detected in real time by the driving pressure detecting means and the driving pressure stored in the storage device while injecting the molten material in the normal filling state with the mold closed, A calculating device for estimating, in real time, an in-mold pressure when a molten material is injected in a filled state, the in-mold pressure estimating device for an injection molding machine. 9. An injection speed detecting means for detecting an injection speed due to a movement of an injection screw, an injection acceleration detecting means for detecting an injection acceleration due to a movement of an injection screw, and a state in which an injection nozzle is separated from a molding die or the molding die. When the molten material is injected with the mold opened, a storage device for storing the injection speed and the injection acceleration detected by the injection speed detection means and the injection acceleration detection means, and melted in a normal filling state with the molding die closed. Based on the difference between the injection speed and the injection acceleration detected in real time by the injection speed detection unit and the injection acceleration detection unit while the material is being injected, and the injection speed and the injection acceleration stored in the storage device, 9. An apparatus for estimating an in-mold pressure in an injection molding machine according to claim 8, further comprising an arithmetic unit for correcting the estimated value of the in-mold pressure. 10. A driving pressure detecting device for detecting a driving pressure of an injection screw in an in-mold pressure estimating apparatus for an injection molding machine for molding a required molded product by injecting a molten material into a molding die cavity by moving an injection screw. Means, an injection speed detecting means for detecting an injection speed due to the movement of the injection screw, an injection acceleration detecting means for detecting an injection acceleration due to the movement of the injection screw, and a state in which an injection nozzle is separated from the molding die or the molding die. When the molten material is injected with the mold opened, injection molding is performed using the driving pressure, injection speed, and injection acceleration of the injection screw detected by the driving pressure detection means, injection speed detection means, and injection acceleration detection means. Computing device for identifying the model parameters of the machine and the molten material, the drive pressure detecting means during the regular filling operation, and the injection speed Estimating in real time the in-mold pressure when the molten material is injected in the normal filling state based on the driving pressure, the injection speed and the injection acceleration of the injection screw detected in real time by the detection means and the injection acceleration detection means, and the model parameters identified above. An in-mold pressure estimating device for an injection molding machine, comprising: 11. A mold information database, a molten material information database, an injection molding machine information database,
An input device and an arithmetic device for determining an in-mold pressure estimation function based on an operator's input from the molding die information database, the molten material information database, and the injection molding machine information database, and detecting operation data when the molten material is injected. An operation for correcting the structure and parameters of the in-mold pressure estimation function using operation data when the molten material is injected with the detection means and the injection nozzle separated from the molding die or with the molding die opened. Apparatus, by giving the mold pressure estimation value when the molten material is injected in the regular filling state and the operating data at the time of regular filling operation to the mold pressure estimation function, the mold pressure at any point in the molding die is real-time. 10. An arithmetic unit for estimating by:
Or an apparatus for estimating an in-mold pressure in an injection molding machine according to item 10.