JP2010234526A - Injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection control device having a simple structure, capable of conducting injection molding flexibly corresponding to various resin materials and shapes of moldings, capable of improving precision of a switching position from a velocity control to a pressure control, and capable of decreasing a variation of a shot volume. <P>SOLUTION: A controlled object device of the device 1 is the injection molding device 2 which includes a cylinder 21 for storing a molten resin, a plunger 22 moving forward and backward in the cylinder 21 to store and inject the resin, and a drive means 24 for driving the plunger 22, and which conducts injection molding in one cycle containing a measuring process of storing the resin in the cylinder 21, an injection process of injecting the resin into a mold M, and a pressure maintaining process of maintaining the pressure of the resin. The device 1 has a selection operation part 10 for selecting and establishing either a feedback control or an open control for each process resulting from dividing one cycle into a plurality of processes, and is capable of conducting injection-molding corresponding to the various resin materials and the shapes of the moldings. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an injection control apparatus in an injection molding apparatus.

  Conventionally, there are an in-line type and a pre-plasticizer type as injection molding apparatuses. In the in-line type, the molten resin is accumulated in the front part of the screw while melting the resin by rotating and retreating the screw in the cylinder (metering process), and the molten resin is injected into the mold by moving the screw forward (injection process) . In the pre-plastic type, the plunger in the cylinder is retracted, the molten resin from the plasticizer that melts the resin provided separately is stored in the front of the plunger (metering process), and the molten resin is made gold by advancing the plunger. Injection into a mold (injection process). Although there is a difference between a screw and a plunger in the pressing body that applies pressure by pressing the resin, the point that the resin in the cylinder is pushed out by the pressing body toward the mold in the injection process and is pressed in the pressure-holding process after the injection process The point that the resin pressure in the mold is kept constant by the body is the same in both types of injection molding apparatuses.

  In the injection molding apparatus, for example, in the pre-plastic type, there is a problem of fluctuation of the measured value after the measuring process. The in-line type has problems such as fluctuations in the injection amount due to malfunction of the check ring, which is a valve element that prevents the resin from leaking backward during injection, fluctuations in the back flow amount due to resin viscosity fluctuations, viscosity reduction due to back flow, and physical property deterioration is there. Further, in both types of injection molding apparatuses, there is a problem that the volume of the next shot is fluctuated due to unevenness of the nozzle lands at the time of mold release. For these problems, countermeasures are taken in accordance with individual devices, resins used, and product shapes (mold shapes).

  As a control item in the injection molding apparatus, there is VP switching for switching a control method from an injection process performed under speed control to a pressure holding process performed under pressure control. Improving and stabilizing the position accuracy of VP switching is an important control issue. In the injection process, the plunger is moved at a high speed under a predetermined set speed, and when the VP is switched, the plunger is rapidly decelerated, and then the resin pressure is kept constant. Inappropriate speed control in the injection process may cause product burns or product deformation due to residual stress, and if VP switching is slow, excessive pressure will be applied to the mold, causing deterioration of the mold or generation of burrs in the product. If the VP switching is too early, a defective product due to insufficient resin amount (short) or insufficient pressure occurs.

  In order to perform VP switching with high accuracy, it is conceivable to control based on the measured value of the resin pressure in the mold, but a pressure sensor is attached to each mold manufactured individually according to many types of products. The installation is problematic in terms of labor and cost. Therefore, an in-mold resin pressure estimation function for estimating the resin pressure in the mold is determined in advance from the drive pressure and injection speed of the injection screw, and the molded product shape information, resin information, and real-time detection are performed on the estimated function. Calculate the estimated value of the resin pressure in the mold in real time by giving the drive pressure of the injection screw and the current injection speed, and feed back the estimated value to the injection speed control system. The reference pressure specified by the resin pressure in the mold An injection control method is known in which the filling speed is controlled so as to satisfy (see, for example, Patent Document 1).

Japanese Patent No. 3569068

  However, in the countermeasures against various problems caused by the above-described VP switching failure and the injection control method as disclosed in Patent Document 1, the former countermeasures are individually addressed in a therapeutic manner. The present injection control method can be used to set a resin pressure estimation function that is effective when molding liquid crystal polymers with little pressure retention using pinpoint gates or submarine gates. Unthinkable.

  The present invention solves the above-mentioned problems, and with a simple configuration, performs various flexible and appropriate controls for various resin materials and molded product shapes, and switches from speed control to pressure control. It is an object of the present invention to provide an injection control device that can improve accuracy and reduce injection volume variation and perform injection molding.

  In order to achieve the above object, a first aspect of the present invention is directed to a cylinder that stores molten resin, a plunger that moves back and forth in the cylinder to store and inject resin, and a drive that drives the plunger back and forth. A metering step for storing resin in the cylinder, an injection step for injecting the resin into a mold communicated with the cylinder, and a pressure holding step for maintaining the pressure of the resin in the mold. An injection control apparatus for an injection molding apparatus that performs injection molding by one cycle including the above, and for each of the processes in which one cycle of the injection molding is divided into a plurality of arbitrary processes, either feedback control or open control is performed. The injection control device includes a selection operation unit for selecting and setting.

  According to a second aspect of the present invention, in the injection control device according to the first aspect, the final stage obtained by dividing the injection process in multiple stages in the selection operation unit is fixed to open control.

  According to a third aspect of the present invention, in the injection control device according to the first or second aspect, the selection operation unit performs an operation of retreating in addition to an operation of advancing or stopping the plunger in the control of the pressure holding process. It can be set freely.

  According to a fourth aspect of the present invention, in the injection control device according to any one of the first to third aspects, the position of the plunger is preset to switch the operation of the plunger from the injection process to the pressure holding process. A position correction unit that corrects the scheduled switching position in real time in one cycle of injection molding based on the plunger position information output from the injection molding apparatus. The position correction unit starts the injection process, and When the resin pressure measured by the pressure sensor provided at the mold inlet exceeds a predetermined threshold, the correction is performed based on the position information of the plunger at that time.

  A fifth aspect of the present invention is the injection control device according to any one of the first to third aspects, wherein the plunger position is preset in order to switch the operation of the plunger from the injection process to the pressure holding process. A position correction unit that corrects the planned switching position in real time within one injection molding cycle based on the plunger position information output from the injection molding apparatus, and one cycle of the injection molding is performed before the injection step. A suck back step of lowering the resin pressure by further retracting the plunger subsequent to the step, and the position correction unit is measured by a pressure sensor facing the cylinder by moving from the suck back step to the injection step. When the resin pressure rises and exceeds a predetermined threshold value, the correction is performed based on the position information of the plunger at that time.

  According to a sixth aspect of the present invention, in the injection control device according to the fourth or fifth aspect, the selection switch for selecting whether or not to correct the planned switching position, and the resin pressure exceeds the threshold value. A data recording unit for recording the position of the plunger at the time and the position of the plunger when switched from the injection process to the pressure holding process.

  According to the first aspect of the present invention, the operator performs a selection operation using the selection operation unit, and flexibly and appropriately adapts to various resin materials and molded product shapes by utilizing the respective advantages of feedback control and open control. Corresponding injection molding is possible. For example, the feedback control can be adjusted to the target injection speed by adjusting the command signal. Open control enables speed switching control in a short time, which is the unit of clock cycle of computer processing, and speed switching with high time resolution and switching from speed control to pressure control (hereinafter referred to as VP switching) in multistage speed control. It can be executed at high speed. Therefore, for example, according to the flow path shape in the mold and the characteristics of the molding material so as to cope with the load fluctuation caused by the flow path cross-section change caused by the mold flow path shape and the solidified state of the resin in injection control. Thus, it is possible to easily assemble a control cycle of an appropriate control method by selecting feedback control and open control for each process obtained by dividing one cycle of injection molding in advance. Therefore, injection molding can be performed under appropriate conditions for various resin materials and molded product shapes, switching position accuracy from speed control to pressure control can be improved, and variation in shot volume can be reduced.

  According to the invention of claim 2, since high-speed processing is performed at the final stage of the injection process for injection molding that requires high-speed injection, the position accuracy of VP switching can be secured with high resolution, and the filling is made highly accurate. can do.

  According to the invention of claim 3, since the plunger can be retracted in the pressure holding step, the plunger can be quickly stopped by the plunger retract command, and VP switching can be performed quickly. In addition, in the pressure holding process, in addition to the pressure reduction due to the shrinkage accompanying the solidification of the resin, the pressure reduction by the backward movement of the plunger can be performed, and in the pressure holding setting for setting the time change profile of the command pressure, a positive number (increase) Both (pressure) and negative numbers (reduced pressure) can be set. Therefore, higher pressure accuracy, for example, 10 millisecond units, can be set by setting the operation for retreating the plunger freely for holding pressure setting and holding pressure control at time intervals of 100 milliseconds when the plunger cannot be retracted. The holding pressure setting and holding pressure control can be performed.

  According to invention of Claim 4, the output of the pressure sensor exceeds the threshold set beforehand using the signal from the pressure sensor embed | buried in the inlet_port | entrance of a metal mold | die, for example, a sprue part or a runner part of a metal mold | die. Thus, the passage of the resin is detected and the planned switching position for the subsequent VP switching is obtained, so that the positional accuracy of the VP switching can be improved, and variations in shot volume and the like can be reduced. Further, since the pressure sensor may be provided not at the mold but at the entrance of the mold, it is not necessary to provide the pressure sensor individually for various molds and can be provided in common in the injection molding apparatus. In this case, since the plunger stroke from the plunger position when the pressure sensor detects the arrival of the resin and exceeds the threshold to the just pack is normally constant, the VP switching position can be obtained with high accuracy in advance. It is possible to correct the set planned switching position. Further, since the subsequent switching position is corrected and set in real time by the passage of the resin, it is effective when a liquid crystal polymer or the like for which the holding pressure hardly works is formed by a pinpoint gate or a submarine gate.

  According to the fifth aspect of the present invention, since the movement of the resin at the start of injection is detected by the change in pressure and the planned switching position is corrected and set, the same effect as in the fourth aspect is achieved. In addition, since the pressure sensor only needs to be provided in the cylinder, not in the mold, a general-purpose injection molding device can easily obtain a pressure value with a simple configuration, and realize a highly versatile control device. Can do.

  According to the sixth aspect of the present invention, based on the information recorded by the data recording unit, the position of the VP switching actually performed and the VP based on the resin pressure measured in the inlet of the mold or in the cylinder. The switching position can be compared. As a result, the remaining stroke amount input as the correction amount can be confirmed and finely adjusted, and can be reflected in the resetting of the speed command value profile in the injection process. High accuracy can be achieved.

The block block diagram of the injection control apparatus which concerns on the 1st Embodiment of this invention. The time variation figure of the control amount and control method in 1 cycle of the injection molding process controlled by the same injection control device. The figure of the setting screen in the selection operation part of the injection control device. The figure of the other setting screen in the selection operation part of the injection control apparatus. The block block diagram of the injection control apparatus which concerns on 2nd Embodiment. The flowchart which shows the example of control by the injection control apparatus. The flowchart which shows the modification of the control by the same injection control apparatus. The block block diagram of the injection control apparatus which concerns on 3rd Embodiment. The flowchart which shows the example of control by the injection control apparatus.

Hereinafter, an injection control device according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
1 to 4 show the first embodiment. As shown in FIG. 1, an injection molding device 2 controlled by the injection control device 1 includes a cylinder 21 that stores molten resin, and a plunger 22 that moves back and forth in the cylinder 21 to store and inject resin. A plasticizing cylinder 23 that supplies molten resin to the cylinder 21 and a drive device 24 that drives the plunger 22 back and forth are provided. The injection molding device 2 faces the inside of the cylinder 21, the plunger position sensor 25 a that acquires the position information L of the plunger 22 in the reciprocating direction of the plunger 22, the pressure sensor 25 b that measures the resin pressure P 1 at the mold inlet, and the cylinder 21. A pressure sensor 25c for measuring the internal resin pressure P2 is provided, and the position information L and information on the resin pressures P1 and P2 are output from the sensor information output unit 25 to the outside.

  The injection control device 1 includes a normal device configuration and software configuration (not shown) for performing injection molding processing in the injection molding device 2, and includes a computer, a signal input / output device, and the like. . In addition to the above-described configuration, the injection control device 1 is a selection operation unit for selecting and setting either the feedback control FB or the open control OP for each process obtained by dividing one cycle of injection molding into a plurality of arbitrary processes. 10 is provided. The selection operation unit 10 is configured, for example, by displaying a window having various selection buttons and tabs on a monitor screen of a computer. For this operation, a pointing device such as a mouse or a light pen, a keyboard, or the like is used. The selection operation unit 10 may be configured using a touch panel or a mechanical switch.

  As shown in FIG. 2, one cycle of injection molding by the injection molding device 2 includes an injection process S1 in which resin is injected into a mold M communicated with a cylinder 21 and a pressure maintaining pressure of the resin in the mold M. Step S2, metering step S3 for storing the resin in the cylinder 21, metering step S3 for storing the resin in the cylinder 21, and if necessary, the plunger 22 is further moved backward following the metering step S3 to change the resin pressure. And a suck-back step S4 for lowering. In order to control the position and speed of the plunger 22 and the resin pressure in each of these steps, a time change profile of the speed command value Vx and a time change profile of the pressure command value Px are set. It is stored in a storage unit (not shown). The injection control device 1 calculates feedback control FB based on the command values Vx and Px, pressure information acquired from the sensor information output unit 25, and position information of the plunger 22, and the drive device 24 is controlled by the calculation result. Operate to make the state of the injection molding device 2 follow the command values Vx and Px. Further, the injection control device 1 performs the open control OP according to the command values Vx and Px to operate the drive device 24, and changes or holds the state of the injection molding device 2.

  Each process included in one cycle of injection molding is designed based on the shape of the product to be injection-molded, that is, the shape of the mold, and the physical properties such as the fluidity, compressibility and specific heat of the resin used. The command values Vx and Px are set. Further, in each process, for example, the injection process S1, the command values Vx and Px are set by being further divided into small processes S11 and S12. In addition, control methods such as feedback control FB and open control OP are assigned to each process and each small process.

  As shown in FIG. 3, by operating the selection setting screen 10a of the selection operation unit 10, it is possible to freely set and change the control method allocation for each small process for each process. . The example of FIG. 3 is an example in which the injection process S1 is divided into multiple stages and either one of the feedback control FB and the open control OP is selectively selected and specified for each small process. Further, as shown in the figure, the final small step S1n obtained by dividing the injection step S1 into multiple stages is fixed to the open control OP, and the feedback control FB cannot be selected. This unselection can be canceled by inputting a password or the like, but can be selected, but cannot be selected in the normal setting. The type of control method set by operating the selection setting screen 10a in this way is indicated by symbols F and O at the bottom of FIG. A small process S13 in FIG. 2 is the final stage of the injection process, and is fixed to open control.

  As shown in FIG. 4, by operating the selection setting screen 10 b of the selection operation unit 10, in addition to the operation of moving the plunger 22 forward or stop in the control of the pressure holding step S <b> 2, the operation of moving backward can be set freely. .

  According to the first embodiment, injection molding can be performed by taking advantage of the respective advantages of the feedback control FB and the open control OP. For example, the feedback control FB can be adjusted to the target injection speed by adjusting the command signal, and the open control OP can perform speed switching control in a short time of a clock cycle unit of arithmetic processing, and the time resolution in the multistage speed control High speed switching, switching from speed control to pressure control (VP switching), etc. can be executed at high speed. For example, in the control of the injection step S1, the flow path shape and the molding material in the mold M are controlled so as to cope with the load fluctuation caused by the change in the flow path cross section caused by the flow path shape of the mold M and the solidified state of the resin. Depending on the characteristics, the operator can select the feedback control FB and the open control OP using the selection operation unit 10 for each process in which one injection molding cycle is divided into a plurality of processes in advance. Can be assembled into.

  Therefore, according to the first embodiment, injection molding can be performed under appropriate conditions flexibly for various resin materials and molded product shapes, and the position accuracy of VP switching from speed control to pressure control can be achieved. It is possible to improve, and it is possible to reduce the variation in shot volume (the amount of resin filled in the mold M each time). In addition, the final stage of the injection process S1 divided into multiple stages is fixed to the open control OP, so that the VP switching position accuracy can be secured with high resolution for injection molding that requires high-speed injection, and the filling is highly accurate. Can be

  Further, since the plunger 22 can be retracted in the pressure holding step S2, the plunger 22 can be quickly stopped by the retracting command of the plunger 22, and VP switching can be performed quickly. Further, in the pressure holding step S2, in addition to the pressure reduction due to the shrinkage accompanying the solidification of the resin, the pressure reduction by the backward movement of the plunger 22 can be performed. In the pressure holding setting for setting the time change profile of the pressure command value, Either a number (pressure increase) or a negative number (pressure reduction) can be set. Therefore, when the plunger 22 cannot be retracted, the pressure holding setting and the pressure maintaining control at a time interval of 100 milliseconds are made higher by setting the operation of retracting the plunger 22 freely, for example, 10 mm. Holding pressure setting and holding pressure control can be performed in seconds.

(Second Embodiment)
5, 6 and 7 show the second embodiment. As shown in FIG. 5, the present embodiment is different from the first embodiment described above in that the injection control device 1 further includes a position correction unit 11, and the others are the same. In the position correction unit 11, the injection molding device 2 outputs a planned switching position (VP switching position) that is a position of the plunger 22 set in advance to switch the operation of the plunger 22 from the injection process S 1 to the pressure holding process S 2. Correction is performed in real time in one cycle of injection molding based on the plunger position information. Such a position correction unit 11 can be configured by a process on a computer constituting the injection control device 1.

  When the injection step S1 is started and the resin pressure P1 measured by the pressure sensor 25b provided at the mold M inlet exceeds a predetermined threshold, the position correction unit 11 is based on the plunger position information L at that time. Correct the planned switching position. The pressure sensor 25b is embedded in the inlet of the mold M, for example, the sprue part or the runner part of the mold M, and at the initial stage of the injection step S1, that is, at the position where the plunger 22 is far from the VP switching position. With the time margin, the information on the resin pressure P1 at the inlet of the mold M can be acquired to detect the passage of the resin. The remaining stroke (distance to the VP switching position) is calculated from the position of the plunger 22 and the remaining filling amount at that time, and correction processing is performed on the planned switching position. By this correction processing, the planned switching position stored in the injection control device 1 is rewritten. The plunger movement amount (stroke) from the position of the plunger 22 when the pressure sensor 25b detects the arrival of the resin and the threshold value is exceeded to the just pack (completion of filling of the resin into the mold M) is usually constant. .

  The VP switching position correction process will be described with reference to FIG. In the continuous molding cycle of the injection molding, the weighing process S3 or the suck back process S4, which is the previous process, is finished, the injection process S1 is started (# 1), and the plunger 22 is moved forward under speed control. After moving (# 2), it is determined whether or not the resin pressure P1 at the mold inlet has exceeded the threshold value (# 3). If not exceeded (No in # 3), the movement in step (# 2) is performed. repeat. If the resin pressure P1 exceeds the threshold value (Yes in # 3), the planned switching position is corrected based on the position information L of the plunger 22 at that time (# 4). Thereafter, the plunger 22 is further moved under speed control (# 5), and based on the position information L of the plunger 22, it is determined whether or not the corrected VP switching position has been reached (# 6). If not reached (No in # 6), the movement of step (# 5) is repeated. If the plunger 22 has reached the VP switching position (Yes in # 6), the pressure holding step S2 is started under pressure control (# 7).

  According to the present embodiment, the pressure sensor used for correcting the VP switching position may be provided not at the mold M but at the inlet of the mold M. There is no need to provide a pressure sensor, and they can be provided in common. Further, since the VP switching position is corrected and set by the passage of the resin, it is effective when a liquid crystal polymer or the like for which pressure holding is hardly effective is formed by a pinpoint gate or a submarine gate.

(Modification of the second embodiment)
A modification of the VP switching position correction process will be described with reference to FIG. In the present modification, assuming that the suck back step S4 is included, the correction process is performed on the VP switching position based on the information on the resin pressure P2 in the cylinder 21, not on the resin pressure P1. The suck back step S4 is a step of lowering the resin pressure P2 in the cylinder 21 by further retracting the plunger 22 following the metering step S3 before the injection step S1 in one cycle of injection molding. Therefore, in the flow of this modification, the end step (# 10) of the suck back step S4 is added before the step (# 1) of the flow of FIG. 6 described above, and the determination regarding the resin pressure P1 at the mold inlet is performed. 6 is different from the flow of FIG. 6 in that step (# 3) is a determination step (# 30) regarding the resin pressure P2 in the cylinder 21. In the determination step (# 30), it is determined whether or not the resin pressure P2 measured by the pressure sensor 25c facing the cylinder 21 has risen and exceeded a predetermined threshold by shifting from the suck back process S4 to the injection process S1. If it is determined (# 3) and the resin pressure P2 exceeds the threshold (Yes in # 30), the planned switching position is corrected based on the position information L of the plunger 22 at that time (# 4). Other steps are the same as the flow of FIG. The resin pressure P2 may be pressure information acquired from the driving device 24.

  As described above, in this modified example, by incorporating the suck back step S4 for retracting the plunger 22 after the metering step S3, the resin is released from the low pressure state until the resin reaches the mold M from the start of injection. The change in the pressure rise due to the start of entering is detected, the remaining stroke is calculated from the position of the plunger 22 and the remaining filling amount at that time, and correction processing is performed at the VP switching position.

  According to the modification of the second embodiment, the movement of the resin at the start of injection is detected by the change in the resin pressure P2 in the cylinder, and the VP switching position is corrected and set. The effect equivalent to the form is produced. Further, since the pressure sensor only needs to be provided not in the mold M but in the cylinder 21, the pressure sensor 25c can be easily installed, and the resin pressure is often already provided in a normal injection molding apparatus. Therefore, the resin pressure P2 in the cylinder 21 can be easily measured by such a pressure sensor, and the highly versatile injection control apparatus 1 can be realized.

(Third embodiment)
8 and 9 show the third embodiment. In the present embodiment, as shown in FIG. 8, the selection switch 12 for selecting whether or not to correct the planned switching position, and the position of the plunger 22 when the resin pressure P1 or the resin pressure P2 exceeds a threshold value, And a data recording unit 13 for recording the position of the plunger 22 when the injection process S1 is switched to the pressure holding process S2, and this is different from the second embodiment described above. As described above, the selection switch 12 can select whether the correction process is valid or invalid. When invalid, the VP switching that has been set in advance as the target value from the position of the plunger 22 when the resin arrival is detected by the pressure sensor. The distance to the position can be recorded for each shot (cycle). Thereby, the remaining stroke amount input as the correction amount can be confirmed.

  As shown in FIG. 9, the injection step S1 is started (# 21), the plunger 22 is moved under speed control (# 22), and the resin pressure P1 or the resin pressure P2 exceeds the threshold value (# 23), the position of the plunger 22 at that time is acquired from the position information L and recorded by the data recording unit 13 (# 24). Furthermore, the plunger 22 is moved (# 25), and when the VP switching scheduled position is reached (Yes in # 26), the position of the plunger 22 at that time is similarly recorded (# 27). Such recording by the data recording unit 13 can naturally be performed even when the correction process of the planned switching position is not invalidated by the selection switch 12, and the recording data when the correction process is invalid can be effectively used. it can.

  According to the present embodiment, based on the information recorded by the data recording unit 13, the position of the actually executed VP switching and the resin pressure measured for the resin in the inlet of the mold M or the cylinder 21 are used. The VP switching position can be compared and examined, and the remaining stroke amount to be input as a correction amount can be checked or determined when the planned switching position is corrected in advance, not in real time. , VP switching position accuracy can be increased.

  The present invention is not limited to the above-described configuration, and various modifications can be made. For example, the configurations of the above-described embodiments can be combined with each other. Moreover, in the said embodiment, although what was called a pre-plaser type | mold apparatus provided with the plasticizing cylinder 23 was demonstrated as an example as an injection molding apparatus, this invention is not limited to a pre-plaser type apparatus, and an in-line type injection molding apparatus. It can also be applied as an injection control device. Further, the division of the injection molding process and the setting of the feedback control FB and the open control OP shown in FIGS. 2 and 3 are examples, and other divisions and setting of the control method can be arbitrarily performed.

DESCRIPTION OF SYMBOLS 1 Injection control apparatus 2 Injection molding apparatus 10 Selection operation part 11 Position correction | amendment part 12 Selection switch 13 Recording part 21 Cylinder 22 Plunger 24 Drive device 25a Plunger position sensor 25b Pressure sensor of a mold inlet 25c Pressure sensor which faces in a cylinder M Mold

Claims (6)

A cylinder that stores molten resin; a plunger that moves back and forth in the cylinder to store and inject resin; and a drive device that drives the plunger back and forth, and at least stores the resin in the cylinder. An injection molding apparatus that performs injection molding by one cycle including a weighing step, an injection step of injecting the resin into a mold communicated with the cylinder, and a pressure holding step for maintaining the pressure of the resin in the mold. An injection control device,
An injection control apparatus comprising: a selection operation unit for selecting and setting either feedback control or open control for each process obtained by dividing one cycle of the injection molding into a plurality of arbitrary processes.   The injection control device according to claim 1, wherein in the selection operation unit, a final stage obtained by dividing the injection process into multiple stages is fixed to open control.   3. The injection according to claim 1, wherein the selection operation unit is configured to freely set an operation of moving the plunger backward or forward in an operation of controlling the pressure holding process. Control device. Based on the plunger position information output from the injection molding device, the planned switching position, which is the position of the plunger set in advance for switching the operation of the plunger from the injection process to the pressure holding process, in real time in one cycle of injection molding. It has a position correction unit to correct,
When the injection process is started and the resin pressure measured by the pressure sensor provided at the mold inlet exceeds a predetermined threshold, the position correction unit performs the correction based on the position information of the plunger at that time. The injection control apparatus according to claim 1, wherein the injection control apparatus performs the injection control apparatus. Based on the plunger position information output from the injection molding device, the planned switching position, which is the position of the plunger set in advance for switching the operation of the plunger from the injection process to the pressure holding process, in real time in one cycle of injection molding. It has a position correction unit to correct,
One cycle of the injection molding includes a suck back step of lowering the resin pressure by further retracting the plunger subsequent to the metering step before the injection step,
When the resin pressure measured by the pressure sensor facing the cylinder rises and exceeds a predetermined threshold by shifting from the suck back process to the injection process, the position correction unit moves the position information of the plunger at that time. The injection control apparatus according to any one of claims 1 to 3, wherein the correction is performed on the basis of the above. A selection switch for selecting whether or not to correct the planned switching position;
The data recording unit for recording the position of the plunger when the resin pressure exceeds the threshold and the position of the plunger when the injection process is switched to the pressure holding process. The injection control device according to claim 4 or 5.

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