KR20170048776A - Method for controlling injection molding machine - Google Patents

Abstract

A method for controlling an injection molding machine comprises the following steps: operating the injection molding machine during a plurality of molding cycles according to predetermined measuring conditions; detecting resin condition values of each molding cycle in temperature or pressure forms during the plurality of molding cycles in which the injection molding machine is operated; and monitoring changes of the resin condition values between the plurality of molding cycles, and controlling measuring conditions so that the resin condition values can follow the predetermined reference values according to monitoring results. Accordingly, resin uniformity between molding cycles can be maintained by corresponding to a change in a resin temperature over time.

Description

METHOD FOR CONTROLLING INJECTION MOLDING MACHINE BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of an injection molding machine, and more particularly, to a control method of an injection molding machine to cope with changes in resin temperature over time to maintain resin uniformity during molding cycles.

The injection molding machine feeds the raw resin to the barrel (or a cylinder), melts the resin in the barrel and measures it, and the metered molten resin is transferred (pressurized) to the nozzle side provided at the tip of the barrel by the screw in the barrel, And a molded product is produced by injection.

The molding cycle of such an injection molding machine is largely divided into a plasticizing / metering process for melting and metering the resin, a filling process for injecting the molten resin into the mold at a proper speed, and a holding process for cooling the mold while constant pressure is applied to reduce the weight deviation of the molded product in the mold Process. After the holding process, the process returns to the weighing process and enters the next molding cycle.

A typical measuring process of the injection molding machine is as follows.

First, the user directly sets the barrel temperature on the basis of the barrel temperature setting condition provided by the resin dealer.

Also, since the weighing for the next injection should be completed within the cooling time, the user arbitrarily sets the weighing rpm of the screw and the back pressure of the screw in consideration of the cooling time.

Then, when re-molding the same mold or the same resin, the user can load the existing weighing conditions (barrel temperature, weighing rpm and back pressure of the screw) and proceed the weighing operation according to the weighing conditions.

On the other hand, generally, the result of molding analysis is used to modify and design the mold, but the difference between the result of analysis such as molding pattern deformation and the actual molded product occurs.

Typically, the actual temperature distribution of the resin at the time of metering becomes uneven, and when the resin temperature is non-uniform, the fluidity (viscosity) of the resin varies depending on the resin temperature (temperature ↑ = viscosity ↓, temperature ↓ = viscosity ↑).

The molding analysis proceeds under the assumption that the temperature of the resin is uniform. In this case, since the viscosity of the resin is the same, the flow pattern is always the same. On the other hand, in the case of yarn molding, the temperature of the resin changes with the lapse of time, which causes the viscosity of the resin to become uneven, and the flow pattern changes even if it is injected at the same speed.

FIG. 1 is an illustration showing an uneven resin temperature distribution (one day production standard) according to the past elapsed time.

In Fig. 1, G11, G12, and G13 indicate the resin temperature, injection load, and weight of the molded article, respectively.

The temperature of the resin used in the injection molding machine varies with time and appears uneven due to environmental influences such as the ambient temperature or the cycle change of the barrel heater (on / off stop time of the barrel heater in a short cycle) ).

When the temperature of the resin is unstable, the viscosity of the resin becomes unstable correspondingly. Therefore, when the resin is injected into the mold, the stress is uneven, the injection load is changed (G12), the cooling is not uniformly performed, Weight deviation (G13) or deformation of the molded article may occur.

That is, even if the same molding conditions are applied for each molding cycle in the case of molding the same mold or the same resin again, the state of the resin is changed with the lapse of time, and due to the uneven state of the resin, And the molding quality is deteriorated.

Korean Patent Laid-Open Publication No. 10-2014-0042701 (published on April 4, 2014).

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art as described above, and its object is to provide a method of manufacturing a plastic mold, which is capable of actively coping with changes in resin temperature due to changes in environment between elapsed time and molding cycles, So that it is possible to prevent defects due to uneven resin temperature and to improve the molding quality, and to provide a control method of an injection molding machine.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.

According to another aspect of the present invention, there is provided a control method for an injection molding machine, including: operating an injection molding machine during a plurality of molding cycles according to predetermined metering conditions; Detecting a resin state value of each molding cycle during the plurality of molding cycles; Monitoring a transition of the resin state value between the plurality of molding cycles; And adjusting the metering condition so that the resin state value follows a predetermined reference value according to the monitoring result.

In the control method of an injection molding machine according to the present invention, the metering condition may be gradually changed so that the resin state value follows the reference value through a plurality of molding cycles that are operated at the time of adjusting the metering condition.

In the control method of the injection molding machine according to the present invention, the resin state value may be the resin temperature, and in this case, if the resin temperature rises from the reference value, the weighing condition value of at least one of the screw metering RPM, back pressure, And if the resin temperature falls from the reference value, it is possible to adjust the direction of increasing the resin temperature by raising the value of at least one of the screw metering RPM, the back pressure, and the barrel temperature.

In the control method of the injection molding machine according to the present invention, the resin state value may be a resin pressure, and in this case, if the resin pressure rises from the reference value, the metering condition value of at least one of the screw metering RPM, back pressure, If the resin pressure falls from the reference value, it can be adjusted in the direction of increasing the resin pressure by raising the weighing condition value of at least one of the screw metering RPM, back pressure and barrel temperature.

In the control method of the injection molding machine according to the present invention, the resin state value may be an injection pressure, and in this case, if the injection pressure is a tendency to rise from the reference value, lower the metering condition value of the screw metering RPM, back pressure, If the injection pressure falls from the reference value, it can be adjusted to increase the injection pressure by raising the weighing condition value of at least one of screw metering RPM, back pressure and barrel temperature.

According to the control method of an injection molding machine according to the present invention, plasticized resin in a uniform state can be supplied in a mold actively responding to a change in resin temperature due to an environmental change between an elapsed time and a molding cycle, And the molding quality can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exemplary illustration of a conventional non-uniform resin temperature distribution.
2 is a schematic structural view of an injection molding machine to which the present invention is applied.
3 is a schematic block diagram of an injection molding machine control apparatus according to an embodiment of the present invention;
4A to 4C are reference views for explaining the operation of the control apparatus shown in Fig. 3; Fig.
5 is a flow chart of a method of controlling an injection molding machine according to an embodiment of the present invention.

Hereinafter, a method of controlling an injection molding machine according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic block diagram of an injection molding machine to which the present invention is applied.

Although the motor-driven toggle injection molding machine is shown in FIG. 2, the injection molding machine to which the present invention is applied is not limited to the electric toggle type, and the present invention may be applied to other types of injection molding machines such as a direct- Of course, it is applicable.

2, an injection molding machine 10 to which the present invention is applied is constituted by an injection apparatus 20 and a mold clamping apparatus 30. As shown in FIG.

The injection apparatus 20 is provided with a barrel 22 and a hopper 21 which is an inflow passage for the solid resin is installed in the barrel 22. A screw (23) is installed inside the barrel (22) so as to be movable forward or backward or rotatably. The rear end of the screw 23 is rotatably supported by the power transmission of the belt pulley through a weighing motor 25 mounted on the support member 28. [

The injection apparatus 20 also has a screw shaft 27 arranged parallel to the screw 23. The rear end of the screw shaft 27 is connected to the output shaft of the injection motor 26 by a timing belt. Therefore, the screw shaft 27 can be rotated by the injection motor 26. The front end of the screw shaft 27 is engaged with a nut fixed to the support member 28. Thus, when the screw shaft 27 is rotated through the timing belt, the support member 28 moves forward or backward, and as a result, the screw 23 can be moved forward and backward.

The mold clamping apparatus 30 has a fixed plate 31 and a movable plate 32 which can be moved. The stationary mold 31 and the movable mold 32 are fitted with a stationary mold 33 and a movable mold 34, respectively. Here, the stationary mold 33 and the movable mold 34 may be referred to as a mold 35. Further, the mold 35 is mold-closed and mold-closed by the mold-clamping apparatus 30, and a molding space corresponding to the mold is formed at the time of molding.

The movable plate (32) and the fixed plate (31) are connected by a tie bar (36). The movable plate 32 is capable of sliding or translating along the tie bar 36.

Further, the mold clamping device 30 has a toggle mechanism 37 connected to the movable plate 32. A rear plate 38 for holding the position of the toggle mechanism 37 is formed at the rear end of the toggle mechanism 37. The toggle mechanism 37 has a plurality of links, and the mold 35 can be mold-closed or mold-shaped according to mutual movement between a plurality of links.

In the mold clamping apparatus 30, when the mold body motor 39 as the driving section is driven, the rotation of the mold body motor 39 is transmitted to the ball screw shaft through the timing belt. Then, the rotational motion is converted into a linear motion by the ball screw shaft and the nut, and the toggle mechanism 37 is operated. The movable plate 32 is moved along the tie bar 36 by the operation of the toggle mechanism 37 and the mold closing and opening operation with the fixed plate 31 is performed.

A nozzle 24 is provided at one end of a barrel 22 provided in the injection apparatus 20 to provide a path for transferring resin. Specifically, the solid resin moved into the barrel 22 through the hopper 21 is melted by forward movement of the screw 23 and heating in the barrel 22. The molten resin is accumulated on the front end of the screw 23 and is metered in a certain amount and is injected through the nozzle 24 at the tip of the barrel 22 and filled into the mold 35 of the mold clamping device 30.

Thereafter, the molten resin filled in the mold 35 is cooled and solidified to complete injection molding, the toggle mechanism 37 is operated through the mold-shaped motor 39 to open the mold 35, and the molded product is discharged from the mold using the ejector do.

3 is a schematic block diagram of an injection molding machine control apparatus according to an embodiment of the present invention.

First, the operation of the injection molding machine 10 during one molding cycle will be described.

The resin supplied from the hopper 21 is supplied to the barrel 22 as the screw 23 in the heated barrel 22 is rotated by the weighing motor 25 under the control of the control device 50, And is accumulated in front of the screw 23 in the barrel 22 by the rotation of the screw 23.

As the molten resin accumulates in front of the barrel 22, the screw 23 receives the pressure (back pressure) of the molten resin, and the screw 23 is retracted based on the predetermined back pressure.

Next, in the filling process, the control device 50 drives the injection motor 26 to advance the screw 23, pushes the molten resin using the tip of the screw 23 as a piston, Is injected through the nozzle (24) and filled in the mold (35). At this time, the screw 23 receives a reaction force, that is, an injection pressure for extruding the molten resin from the nozzle 24.

Next, at the time of completion of the injection at which the molten resin is filled in the cavity of the mold 35 in the pressure holding process, the forward movement of the screw 23 is switched from the speed control to the pressure control so as to maintain the predetermined pressure, For a certain period of time.

When the molten resin filled in the mold 35 is cooled and solidified under a predetermined pressure and injection molding is completed, the control device 50 operates the toggle mechanism 37 through the mold-shaped motor 39 to open the mold 35, The molded product is discharged from the mold.

The control device 50 operates the injection molding machine 10 in such a normal molding cycle and the injection molding machine 10 produces a plurality of molded products while repeating the molding cycle under the control of the control device 50. [

However, as described above, the resin temperature changes according to the environmental change between the molding cycles as time elapses (see Fig. 1), and the metering resin of stable quality is stuck to the mold 35 due to the uneven resin condition (temperature and viscosity) Which is a cause of lowering the molding quality.

The control device 50 according to an embodiment of the present invention optimally adjusts metering conditions between molding cycles in response to changes in resin temperature between molding cycles to uniformize the state of the resin that changes with time will be.

The control device 50 may include a driving control unit 51, a detection unit 52, a monitoring unit 53, and an adjustment unit 54. [

The operation control unit 51 sets the weighing conditions in advance and operates the injection molding machine 10 for a plurality of (two or more) molding cycles in accordance with the corresponding weighing conditions, so that several (two or more) .

At this time, the weighing conditions may include barrel temperature, weighing rpm of the screw, back pressure of the screw, and other weighing information.

For example, the user directly sets the barrel temperature based on the barrel temperature setting condition provided by the reseller, sets the weighing distance by calculating the amount of resin necessary for forming the molded product, and sets the weighing completion time.

In this case, the operation control unit 51 can determine the weighing rpm of the screw for measuring a certain amount based on the plasticizing ability (kg / hr) of the screw 23.

(Barrel temperature, weighing rpm of the screw, back pressure of the screw, etc.) applied in the molding of the same mold or the same resin as before.

The detection unit 52 detects the resin state value for each molding cycle while a plurality of molding cycles are performed and the injection molding machine 10 is operated.

At this time, the detection unit 52 may be any one of a load cell 52a, a nozzle-side pressure sensor 52b, and a nozzle-side temperature sensor 52c.

3, the load cell 52a is provided behind the screw 23 and detects the injection pressure applied to the front of the screw 23 during the molding cycle and provides it to the control device 50. [

The nozzle side pressure sensor 52b is provided on the nozzle 24 side of the barrel 22 and directly detects the resin pressure during the molding cycle and provides it to the control device 50. [

The nozzle side temperature sensor 52c is provided on the nozzle 24 side of the tip end of the barrel 22 and detects the resin temperature during the molding cycle and provides it to the control device 50. [

Since the viscosity and temperature of the resin are closely related, the uniformity (uniformity) of the resin can be confirmed by only one state value of the two.

In addition, if the viscosity of the resin is not uniform, injection pressure or resin pressure appears unevenly even if the resin is injected at the same speed.

Therefore, by using any one of the resin temperature, the injection pressure and the resin pressure as the resin state value of each molding cycle as a reference for adjusting the weighing conditions between molding cycles, it is possible to determine whether the uniformity of the resin, .

The resin state value obtained through the detection unit 52 may be the resin temperature measured through the nozzle side temperature sensor 52c or the injection pressure measured through the load cell 52a or the injection pressure measured through the nozzle side pressure sensor 52b It may be the measured resin pressure.

The resin state value may be a representative value detected for each molding cycle (e.g., an injection section), or may be a plurality of values detected periodically or at specific time points during each molding cycle, or an average thereof.

The monitoring unit 53 receives the resin state value of each molding cycle obtained through the detecting unit 52 and monitors the change of the resin state value between a plurality of molding cycles.

That is, the above-described monitoring unit 53 monitors the injection pressure change for each molding cycle detected by using the load cell 52a over a plurality of molding cycles, The pressure change can be monitored, or the resin temperature change per molding cycle detected through the nozzle side temperature sensor 52c can be monitored.

The adjustment unit 54 adjusts the metering condition so that the resin state value follows the predetermined reference value based on the monitoring result of the monitoring unit 53. [

At this time, the adjusting unit 54 may reset one or more of the barrel temperature, the metering rpm of the screw, and the back pressure of the screw in the metering conditions according to the monitoring result.

That is, the adjusting unit 54 adjusts the injection pressure so that the injection pressure between the molding cycles recognized through the load cell 52a follows a predetermined reference value, or the resin pressure within the molding cycle identified through the nozzle-side pressure sensor 52b follows the reference value The barrel temperature, the screw metering rpm, and the back pressure can be selectively or simultaneously adjusted so that the resin temperature identified through the nozzle side temperature sensor 52c follows the reference value.

When the barrel temperature / screw metering rpm / back pressure adjustment according to the injection pressure / resin pressure / resin temperature change is completed, the metering condition including the metering condition is updated and the injection molding machine 10 can be operated under the metering condition adjusted in the subsequent molding cycle .

As such, the control device 50 monitors the inter-molding cycle resin temperature transition measured through the nozzle side temperature sensor 52c, monitors the inter-molding cycle resin pressure transition measured through the nozzle side pressure sensor 52b , The injection pressure trend measured through the load cell 52a is monitored to determine the uniformity of the resin, and the weighing condition (at least one of the barrel temperature, the screw metering rpm and the back pressure) can be adjusted so that the resin state between the molding cycles becomes uniform have.

For this purpose, the control device 50 also measures at least one resin state value in the form of temperature or pressure, for example, at least one time point during the molding cycle (for example, at an intermediate point of the injection section, etc.) This can be recorded to monitor trends.

Based on the monitoring result, it is possible to determine whether the resin state value between the molding cycles is maintained in a certain range or whether it changes to an ascending / descending trend, so that the accounting conditions can be flexibly adjusted to be applied to the subsequent molding cycle in real time have.

For example, the control device 50 detects the resin temperature at one or more of the injection sections of the N-2, N-1, and N-th molding cycles, monitors the change in the resin temperature, The adjusted metering condition can be newly applied to the metering section of the (N + 1) th molding cycle by adjusting at least one of the barrel temperature / screw metering rpm / back pressure.

That is, the metering condition is adjusted so that the resin state value follows the reference value according to the result of monitoring the resin state value between the molding cycles, so that the injection molding machine 10 can be operated under the adjusted metering condition in the subsequent molding cycle.

Figs. 4A to 4C illustrate changes in the uniformity of the resin temperature due to adjustment of the metering condition. Fig.

4A is a graph comparing the resin temperature in accordance with the high-speed rotation G21 / low-speed rotation G22 of the screw 23 at the time of metering. Fig. 4B is a graph showing the relationship between the resin temperature FIG. 4C is a comparison of resin temperatures when the barrel temperature is higher (G41? G42) at the time of metering.

4A to 4C, it can be seen that by lowering the metering rpm of the screw, increasing the back pressure, or increasing the barrel temperature, the uniformity can be improved by reducing the resin temperature / viscosity variation.

On the other hand, if the viscosity of the resin is not uniform, injection pressure or pressure of the resin unevenly appears when injected at the same speed.

Therefore, by using this point, it is also possible to determine the uniformity of the resin between the molding cycles by using the resin state value in the form of pressure in addition to the temperature.

The adjustment section 54 of the control device 50 described above selectively adjusts the metering condition such as the barrel temperature / screw metering rpm / back pressure so that the resin state value (at least one of the resin temperature, the resin pressure and the injection pressure) Or at the same time.

For example, if the injection molding machine 10 is operated for 24 hours a day to produce 100 identical molded articles, 100 molding cycles are repeated.

In this case, if the reference value of the resin temperature is set at 100 占 폚 and the injection molding machine 10 is operated in the initial three molding cycles under the same weighing condition and the resin temperature trends are detected as 102 占 폚, 105 占 폚 and 107 占 폚, ) Monitors the change in the resin temperature during the molding cycle and lowers the barrel temperature, lowers the metering RPM of the screw, and lowers the back pressure of the screw, so that the resin temperature follows the reference value of 100 占 폚, based on the monitoring result.

This adjusted metering condition is immediately applied to the subsequent molding cycle to lower the resin temperature.

If the resin temperature trends are again detected at 103 ° C, 98 ° C and 94 ° C in the subsequent three molding cycles, the control device 50 monitors the change in the resin temperature during the molding cycle to determine whether the resin temperature is 100 ° C Increase the barrel temperature again, increase the metering RPM of the screw, or increase the back pressure of the screw.

According to this, it is possible to realize an optimum metering condition in real time during a normal molding cycle without adjusting a metering condition by providing a separate section.

Further, the adjustment section 54 may gradually change the metering condition for each molding cycle so that the resin state value follows the reference value through a plurality of molding cycles to be operated subsequently.

In this case, the adjustment unit 54 adjusts the metering condition so that the resin state value is lowered if the resin state value obtained through the detection unit 52 is rising from the reference value, and if the resin state value is falling from the reference value, The weighing conditions can be adjusted stepwise to increase the value.

That is, if the monitored resin condition value (resin temperature / resin pressure / injection pressure) is a tendency to rise from the reference value, then gradually decrease the weighing condition value of at least one of screw weighing RPM, screw back pressure and barrel temperature, And if the resin state value falls from the reference value, the weighing condition value of at least one of the weighing RPM, back pressure, and barrel temperature of the screw is gradually increased to adjust the resin state value in the direction of increasing the resin state value.

5 is a flowchart of an injection molding machine control method according to an embodiment of the present invention.

In the control device 50, the weighing conditions including the barrel temperature, the screw metering rpm, the back pressure and the like are preset and stored according to the user setting value or the existing molding cycle.

The control device 50 operates the injection molding machine 10 for a plurality of molding cycles according to predetermined metering conditions (S10).

In addition, the control device 50 detects the resin state value of each molding cycle during a plurality of molding cycles through the above-described S10 (S20), and monitors the change of the resin state value between a plurality of molding cycles (S30 ).

In one embodiment, it is assumed that the resin state value detected and monitored through S20 and S30 is the resin temperature measured through the nozzle side temperature sensor 52c in order to maintain resin uniformity between molding cycles.

The other resin state values may be the injection pressure of each molding cycle measured through the load cell 52a or the resin pressure of each molding cycle measured through the nozzle side pressure sensor 52b.

Thereafter, the control device 50 adjusts the metering condition so that the resin temperature follows the preset reference value, based on the monitoring result at S30 described above (S40). The weighing conditions to be adjusted at this time may include one or more of barrel temperature, screw metering rpm, and screw back pressure.

S40 for adjusting the weighing conditions will be described in more detail as follows.

First, the controller 50 determines whether or not the resin temperature is within a predetermined range based on the monitoring result of S30 described above (S41). If it is determined that the resin temperature is out of the predetermined range, the control device 50 proceeds to S42 or S44, I understand.

If it is determined in S30 that the resin temperature is rising from the reference value (S42), the control device 50 adjusts the metering condition so as to lower the resin temperature (S43). At this time, the metering condition can be adjusted to lower the resin temperature by lowering the metering condition value of one or more of the metering RPM, back pressure, and barrel temperature of the screw.

In this case, the rising trend of the resin temperature means not only the case where the resin temperature continuously increases over several molding cycles but also the case where the resin temperature higher than the reference value is maintained for a predetermined time or longer, And the like.

On the other hand, if it is determined in S30 that the resin temperature is falling from the reference value (S44), the control device 50 adjusts the metering condition so as to increase the resin temperature (S45). At this time, the weighing condition can be adjusted in the direction of increasing the resin temperature by raising the weighing condition value of one or more of the weighing RPM, back pressure and barrel temperature of the screw.

In this case, the lowering trend of the resin temperature means not only the case where the resin temperature is continuously lowered but also the case where the resin temperature lower than the reference value is maintained for a predetermined time or the resin temperature lower than the reference value is detected more than the reference number for a predetermined time It is meant to include all.

If the monitored resin temperature value is the resin temperature, if the resin temperature is rising from the reference value as a result of monitoring in S30 (S42), the metering condition value of at least one of the metering RPM of the screw, the back pressure of the screw, (S43). If the resin temperature is lowered from the reference value as a result of monitoring in S30 (S44), one or more of the weighing RPM, back pressure, and barrel temperature of the screw is increased to increase the resin temperature (S45).

As another example, if the monitored resin state value is the resin pressure, if the resin pressure rises from the reference value, the metering condition value of at least one of the metering RPM of the screw, the screw back pressure, and the barrel temperature is lowered to decrease the resin pressure And if the resin pressure falls from the reference value, the weighing condition value of at least one of the weighing RPM of the screw, the back pressure, and the barrel temperature may be increased to adjust the resin pressure in the direction of increasing the resin pressure.

As another example, if the monitored resin state value is the injection pressure, if the injection pressure is rising from the reference value, the metering condition value of at least one of the metering RPM of the screw, the screw back pressure, and the barrel temperature is lowered to lower the injection pressure And if the injection pressure falls from the reference value, the metering condition value of at least one of the metering RPM of the screw, the back pressure, and the barrel temperature may be increased to adjust the injection pressure in the direction of increasing the injection pressure.

In addition, in S43 or S45 described above, the control device 50 may gradually change the metering condition so that the resin state value including the resin temperature follows the reference value through a plurality of subsequent molding cycles.

Accordingly, the deviation of the resin state value measured in the form of temperature or pressure is reduced, so that the resin uniformity between molding cycles can be maintained.

The configuration of the control method of the injection molding machine according to the present invention is not limited to the above-described embodiments, but can be variously modified and carried out within the scope of the technical idea of the present invention.

10: Injection molding machine
50: Control device
51:
52:
52a: Load cell
52b: pressure sensor on the nozzle side
52c: Nozzle side temperature sensor
53: Monitoring section
54:

Claims (5)

Operating the injection molding machine for a plurality of molding cycles according to predetermined metering conditions;
Detecting a resin state value of each molding cycle during the plurality of molding cycles;
Monitoring a transition of the resin state value between the plurality of molding cycles; And
And adjusting the metering condition so that the resin state value follows a preset reference value according to the monitoring result.
The method according to claim 1,
Wherein the metering condition is gradually changed so that the resin state value follows the reference value through a plurality of molding cycles that are operated at the time of adjusting the metering condition.
The method according to claim 1,
Wherein the resin state value is a resin temperature,
If the resin temperature tends to rise from the reference value, the weighing condition value of at least one of the screw metering RPM, back pressure, and barrel temperature is lowered to adjust the resin temperature to a lowering direction,
Wherein when the resin temperature is a tendency to descend from the reference value, at least one of the screw metering RPM, the back pressure and the barrel temperature is increased to adjust the resin temperature in the direction of increasing the resin temperature.
The method according to claim 1,
Wherein the resin state value is a resin pressure,
If the resin pressure is rising from the reference value, the weighing condition value of at least one of screw metering RPM, back pressure, and barrel temperature is lowered to adjust the resin pressure in a direction to lower the resin pressure,
Wherein when the resin pressure is falling from the reference value, at least one of the screw metering RPM, the back pressure and the barrel temperature is increased to adjust the resin pressure in the direction of increasing the resin pressure.
The method according to claim 1,
Wherein the resin state value is an injection pressure,
If the injection pressure is a tendency to rise from the reference value, the metering condition value of at least one of screw metering RPM, back pressure, and barrel temperature is lowered to adjust the injection pressure to a lowering direction,
The injection pressure is increased in the direction of increasing the weighing condition value of at least one of screw metering RPM, back pressure, and barrel temperature when the injection pressure is falling from the reference value.

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