JP2014040090A - Injection molding machine having resin supply amount regulation part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine having a resin supply amount regulation part that can perform material supply to keep an appropriate starvation state without requiring a special detector for detecting a molding material in a groove of a screw, and further regardless of a measuring revolution speed.SOLUTION: An initial value of a supply amount command value F is set, an injection and pressure keeping process is performed, measurement is initiated, the supply amount command value F of a resin is calculated so that screw resistance force may become a target value (SA01-SA04), the resin is supplied based on the supply amount command value F calculated in a prior cycle, when the measurement is finished, a decompression process is performed (SA05-SA07), and an absolute value of force which the screw receives is detected as screw resistance force, when being not operation completion, the treatment is returned back to the step SA02 and is continued, and when being operation completion, the treatment is finished (SA08, SA09).

Description

  The present invention relates to an injection molding machine, and more particularly to an injection molding machine having a resin supply amount adjusting unit.

As a method for supplying pellets as molding materials to the injection cylinder of an injection molding machine, a method is generally used in which pellets are stored in a supply hopper connected to the injection cylinder and the pellets are fed into the injection cylinder using its own weight. It is used for. In this case, the resin supply port of the injection cylinder is in a state filled with pellets. Hereinafter, this state is referred to as a full state.
On the other hand, so-called starvation supply is known in which pellets are supplied little by little so that the resin supply port of the injection cylinder becomes sparse. For example, Patent Document 1 discloses a technique for controlling a pellet supply speed by providing a pellet feeder between a pellet supply source and an injection cylinder and increasing or decreasing the feed speed of the pellet feeder (Patent Document 1). 1 (see FIG. 1).

  When starvation is performed, degassing of the gas generated in the injection cylinder from the resin supply port is promoted, or wear of the injection cylinder inner wall due to friction between the injection cylinder inner wall and the resin material in the vicinity of the resin supply port is suppressed. The effect is expected. However, when the density state (starvation state) of the resin material at the resin supply port varies, the plasticization quality of the resin in the metering process varies, which may adversely affect the molding quality. Therefore, when the hunger supply is performed, there is a problem that the material supply must be performed so that the hunger state is kept constant.

In Patent Document 2, a molding material detection unit that is disposed facing a supply unit in a screw and detects a molding material in the groove of the screw, and a screw groove corresponding to the detection result by the molding material detection unit. A technique for controlling the supply amount of the resin material is disclosed so that the molding material is not filled 100%. However, there is a problem that a special detection unit for detecting the molding material in the groove of the screw is required.
Patent Document 3 discloses a technique for detecting the screw rotation torque in the weighing process and adjusting the supply amount of the raw material so that the screw rotation torque matches a reference value. However, depending on the type of resin material, the screw rotation torque may not change even if the starvation state fluctuates. In such a case, the starvation state cannot be controlled based on the screw rotation torque. was there.

On the other hand, in Patent Document 4, a determination unit determines a difference between an actual measurement time during a plasticizing process and a preset reference measurement time, and controls a material supply amount by a material supply device based on the determination result. Techniques to do this are disclosed. However, since the measuring time varies depending on the screw rotation speed, there is a problem that the starvation state cannot be accurately determined.
In Patent Document 5, when a color change operation is performed using a color change target material, in a material supply device that intermittently opens and closes a resin passage and intermittently supplies a raw material resin to a feed unit, the supply start time of the color change resin is set. As a determination criterion to be determined, a technique for setting the elapsed time or the total number of screw rotations is disclosed.

In Patent Document 6, monitoring is performed by determining whether or not measurement data corresponding to each monitoring item set in advance is within an allowable range from measurement information of sensors disposed in each part of the injection molding machine. In an injection molding machine, a technique is disclosed in which a screw rotation amount from the screw rotation start time is cumulatively calculated, and this screw rotation amount is used as one of monitoring items during a charge / metering process.
Patent Document 7 discloses a technique for detecting the screw rotation amount in a predetermined section and adjusting the resin supply amount of the resin supply unit so that the detected screw rotation amount becomes a predetermined target value.
Patent Document 8 discloses a technique for detecting a physical quantity that changes in accordance with a material retention amount or a positional density distribution in an injection cylinder and changing a material supply amount by a quantitative supply unit based on the detection result. ing.

JP-A-5-318531 JP 2002-248655 A Japanese Patent Laid-Open No. 53-11957 JP-A-1-171830 JP-A-3-114813 JP-A-3-118132 JP 2012-000962 A JP 2001-347545 A

  Therefore, in view of the above-described problems of the prior art, the present invention does not require a special detection unit for detecting the molding material in the groove of the screw, and is not affected by the magnitude of the measurement rotation speed. It is an object of the present invention to provide an injection molding machine having a resin supply amount adjustment unit capable of supplying a material so as to maintain a starvation state.

The invention according to claim 1 of the present application includes an injection cylinder, a screw, a screw forward / reverse drive unit that drives the screw in the forward / backward direction, a force detection unit that detects a force that the screw receives in the axial direction, and the injection cylinder In an injection molding machine having a resin material supply unit for supplying a resin material therein, a screw resistance force calculation unit that calculates a screw resistance force based on a detection value of the force detection unit, and the screw resistance force increases Therefore, an injection molding machine having a resin supply amount adjusting unit for reducing the resin supply amount of the resin material supply unit.
The invention according to claim 2 is characterized in that the screw resistance force calculation unit calculates, as a screw resistance force, an absolute value of a detection value of the force detection unit at an arbitrary time from the completion of the decompression step to the start of screw advancement. The injection molding machine according to claim 1.
According to a third aspect of the present invention, the screw resistance force calculation unit starts when the detection value of the force detection unit starts to increase during screw advance from when the detection value of the force detection unit does not decrease during decompression. 2. The injection molding machine according to claim 1, wherein an absolute value of a detection value of the force detection unit at an arbitrary point in time is calculated as a screw resistance force.

The invention according to a fourth aspect further includes a resin pressure detection unit that detects a resin pressure in front of the screw in the first aspect, and the screw resistance calculation unit calculates the resin pressure from a detection value of the force detection unit. 2. The injection molding machine according to claim 1, wherein a value obtained by multiplying a detection value of the detection unit by a screw cross-sectional area is subtracted, and an absolute value of the calculated value is calculated as a screw resistance force.
The invention according to claim 5 includes a resin pressure detection unit that detects a resin pressure in front of the screw, and the screw resistance calculation unit calculates the resin from a value obtained by dividing a detection value of the force detection unit by a screw cross-sectional area. The injection molding machine according to claim 1, wherein the detection value of the pressure detection unit is subtracted and an absolute value of the calculated value is calculated as a screw resistance force.
The invention according to claim 6 is characterized in that the resin supply amount adjusting unit adjusts the resin supply amount of the resin material supply unit so that the screw resistance becomes a predetermined target value. It is an injection molding machine as described in any one of -5.

  According to the present invention, a special detection unit for detecting the molding material in the groove of the screw is not required, and the material supply is performed so as to maintain an appropriate starvation state without being affected by the magnitude of the measurement rotation speed. It is possible to provide an injection molding machine having a resin supply amount adjustment section that can be performed.

It is a figure explaining the injection molding machine which has a resin supply amount adjustment part. It is a flowchart of the process which performs resin supply amount adjustment based on the absolute value of the force which the screw receives in the arbitrary time after a decompression process completion to a screw advance start. Adjust the resin supply amount based on the absolute value of the force received by the screw at any time from when the force received by the screw during pressure reduction stops to the point when the force received by the screw during screw advance starts to increase. It is a flowchart of the process to perform. It is a flowchart of the process which performs resin supply amount adjustment based on the screw resistance force which excluded the influence by the resin pressure P ahead of a screw from the force D which a screw receives. It is another flowchart of the process which adjusts resin supply amount based on the screw resistance force which excluded the influence by the resin pressure P ahead of a screw from the value which remove | divided the force D which a screw receives with a screw cross-sectional area.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
When the resin supply port of the injection cylinder is filled with pellets, that is, when the starvation state is dense, the resin in the semi-molten state at the base of the screw becomes resistant to the forward and backward movement of the screw, and the screw is in the direction opposite to the traveling direction. (Hereinafter referred to as “screw resistance”). On the other hand, when the starvation state is sparse, the screw resistance is small because there is little semi-molten resin at the screw root. The present invention pays attention to this characteristic, and appropriately controls the supply amount of the resin material based on the screw resistance force that the screw receives in the axial direction. That is, by detecting the screw resistance force that the screw receives in the axial direction and decreasing the supply amount of the resin material as the detected resistance force increases, the material is supplied so as to maintain an appropriate starvation state. is there.

  FIG. 1 is a block diagram illustrating an injection molding machine having a resin supply amount adjusting unit according to the present invention. Reference numeral 1 in the drawing denotes a screw of an injection molding machine, which is fitted in the injection cylinder 2 so as to be movable and rotatable in the axial direction. The injection servo motor M1 and the screw rotation servo motor M2 perform the axial injection operation and the shaft rotation. The screw rotation is performed independently. Reference numeral 31 denotes a power transmission mechanism for causing the screw 1 to perform an injection operation using the injection servomotor M1 as a drive source, and reference numeral 32 denotes a screw for causing the screw to perform a metering operation using the screw rotation servomotor M2 as a drive source. It is a power transmission mechanism. The injection cylinder 2 is provided with a heating unit (not shown) made up of a band heater or the like.

Further, a hopper 4 for charging pellets as a molding material is provided on the upper surface of the base of the injection cylinder 2, and the pellets in the hopper 4 are placed between the hopper 4 serving as a pellet supply source and the injection cylinder 2. A pellet feeder 5 for supplying the injection cylinder 2 is provided.
The pellet feeder 5 includes a rotor 7 with a blade disposed so as to traverse a communication path 6 formed between the hopper 4 and the injection cylinder 2, a motor M3 that is a rotation driving unit of the rotor 7 with a blade, and the motor M3. Of the pellets fed from the hopper 4 to the injection cylinder 2 by controlling the rotational speed of the bladed rotor 7 based on the resin supply amount command value F. Has been adjusted.

  In addition, it replaces with the rotor 7 with a blade | wing which comprises the principal part of the pellet feeder 5, and applies the structure of the resin supply screw and its peripheral part, and the resin supply screw is rotationally driven with the motor M3, and a pellet is injected into the injection cylinder 2. You may make it send. The rotary encoders P1 and P2 are mounted on the injection servo motor M1 and the screw rotating servo motor M2, respectively, so that the current position (axial direction), rotational position (around the axis), and the like of the screw 1 are detected. It has become.

  The injection molding machine control device 100 has a numerical control microprocessor (hereinafter referred to as CNCCPU) 111 and a programmable machine controller microprocessor (hereinafter referred to as PMCCPU) 113. The PMCCPU 113 includes a sequence operation of the injection molding machine and the like. A ROM 116 storing a sequence program for controlling the pellet feeder 5, a nonvolatile PMC RAM 109 and a current value storage RAM 108 are connected. The CNC CPU 111 is for overall control of each part of the injection molding machine, and includes a servo motor for each axis for clamping (not shown), ejector (not shown), screw rotation, injection, etc. A servo circuit that controls driving is connected via a servo interface 110. In FIG. 1, only the servo circuit 102 for the injection servo motor M1 and the servo circuit 101 for the screw rotation servo motor M2 are shown.

  A non-volatile shared RAM 104 has a memory unit for storing an NC program for controlling each operation of the injection molding machine, and a setting memory unit for storing various setting values, parameters, macro variables, and the like. The section stores various molding conditions, weighing conditions, and the like set and input by the operator via the manual data input device 117 with an LCD display and the operator panel controller 115. Reference numeral 112 denotes a bus arbiter controller (hereinafter referred to as BAC). The BAC 112 is connected to the buses of the CNC CPU 111 and the PMC CPU 113, the shared RAM 104, the input circuit 105, and the output circuit 106 so that the bus used by the BAC 112 is controlled. It has become.

  The injection servo motor M1 is connected to the servo circuit 102, and the detection output from the rotary encoder P1 is input to the servo circuit 102. The current position (axis) of the screw 1 is stored by the current position storage register in the servo interface 110. Direction) is always detected. The screw rotation servomotor M2 is connected to the servo circuit 101, and the detection output from the rotary encoder P2 is input to the servo circuit 101 to control the position and speed. A RAM 103 is a calculation data storage memory for the CNC CPU 111.

  A motor drive circuit 8 is connected to the output circuit 106 of the control device 100 via a D / A converter 9, and the motor is driven by a speed command from the control device 100 D / A converted by the D / A converter 9. The drive circuit 8 drives and controls the motor M3, and the bladed rotor 7 of the pellet feeder 5 supplies the pellets in the hopper 4 to the injection cylinder 2 at a feed speed corresponding to the speed command from the control device 100. Yes.

  In the above-described configuration, the CNC CPU 111 performs injection control while the PMC CPU 113 performs sequence control according to the NC program stored in the CNC ROM 114, various molding conditions stored in the shared RAM 104, the sequence program stored in the PMC ROM 116, and the like. The injection molding machine is driven and controlled by distributing pulses to the servo circuit of each axis of the molding machine via the servo interface 110. As far as the injection molding machine main body is concerned, the drive control system of each part is exactly the same as the conventional one. is there.

  That is, in the measurement / kneading process, the CNC CPU 111 controls the drive of the injection servo motor M1 based on the back pressure preset in the shared RAM 104, and receives a measurement start signal from the PMC CPU 113. The CNC CPU 111 starts pulse distribution for each predetermined period via the servo interface 110 in accordance with the screw rotation speed preset in the shared RAM 104, and includes an error register, an F / V converter, an error amplifier, a power amplifier, and the like. The servo circuit 101 performs position, speed, and current loop processing based on the distribution pulse from the CNC CPU 111 and the feedback pulse from the rotary encoder P2, and the screw rotation servomotor so that the rotation speed of the screw 1 becomes the set speed. Control M2. Although not shown, the injection molding machine is provided with a force detector such as a strain gauge or a load cell between the screw 1 and the screw driving unit in order to detect the force that the screw receives in the axial direction. Furthermore, a pressure sensor for detecting the resin pressure can be provided in the front portion of the injection cylinder 2. Output signals from these force detectors and pressure sensors are sent to the control device 100 via the input circuit 105.

  The above-described injection molding machine and its control device execute the process of the flowchart showing the algorithm according to the present invention shown in FIGS. 2 to 5 and realize an injection molding machine having a resin supply amount adjusting unit. It has a function to do.

<Screw resistance calculation unit>
Screws receive resistance (screw resistance) from the semi-molten resin at the base of the screw. In molding processes such as injection and pressure holding, the resin pressure is also applied from the molten resin in front of the screw in addition to the screw resistance. Receive proportional force. The force due to the resin pressure has no correlation with the density of the starvation state and does not serve as an index of the starvation state. Therefore, it is necessary to detect only the screw resistance force by excluding the force due to the resin pressure.

  In general, in the injection molding process, after the weighing process, a decompression process is performed in which the screw is retracted to reduce the resin pressure. In some molding methods, a pressure reducing step is performed after the pressure holding step (pre-depressurization), and then a measuring step is performed. Since the resin pressure has been reduced after completion of the decompression step, the force that the screw receives in the axial direction and the screw resistance force substantially coincide between the completion of the decompression step and the start of screw advancement. Therefore, the absolute value of the force that the screw receives in the axial direction at any time from the completion of decompression to the advance of the screw may be detected as the screw resistance force (see step SA08 in FIG. 2).

  Also, the screw is subjected to the axial direction from any time when the resin pressure is reduced, that is, from the time when the resin pressure is reduced during the backward movement of the screw to the time when the resin pressure starts to increase during the forward movement of the screw. This is the timing at which the force and the screw resistance force substantially coincide. At this time, if the resin pressure is not reduced, the force that the screw receives in the axial direction decreases by retreating the screw. However, if the resin pressure is reduced, the force that the screw receives in the axial direction even if the screw is retracted. If the resin pressure is reduced and the resin pressure is reduced, the force applied to the screw in the axial direction will not increase even if the screw is advanced, but if the resin pressure increases again as the screw continues to advance, the screw will move in the axial direction. Focusing on the increase in the force received, any time from when the force that the screw receives in the axial direction during the screw retraction stops to decrease until the force that the screw receives in the axial direction during the screw advancement starts increasing The absolute value of the force that the screw receives in the axial direction at the time may be detected as a screw resistance force (see steps SB04 and SB13 in FIG. 3). .

  A pressure sensor that detects the resin pressure is provided at the nozzle and the front part of the injection cylinder. The force due to the resin pressure is calculated based on the resin pressure detected by the pressure sensor, and the force due to the resin pressure is excluded from the force received by the screw. You may make it calculate a screw resistance. In this case, since the screw resistance force can be calculated based on the detected value of the resin pressure even if the resin pressure is not reduced, the screw resistance force can be calculated at an arbitrary time. For example, the absolute value of the value obtained by subtracting the value obtained by multiplying the detected value of the resin pressure by the screw cross-sectional area from the force that the screw receives in the axial direction at an arbitrary time point is detected as the screw resistance force. (Refer to step SC05 in FIG. 4).

  Or after converting the force which a screw receives into the unit of a pressure, you may make it calculate a screw resistance force excluding the component of resin pressure. For example, the absolute value of the value obtained by subtracting the detected value of the resin pressure from the value obtained by dividing the axial force of the screw in the axial direction at an arbitrary time point is detected as the screw resistance force. (Refer to step SD05 in FIG. 5).

<About decompression process>
In the decompression step, the resin pressure may be reduced by moving the screw backward, or the resin pressure may be reduced by rotating the screw in a direction opposite to the metering direction. Also, it may be determined that the resin pressure has been reduced when the axial force applied to the screw does not decrease even if the screw is retracted during the decompression process, or the screw is rotated in reverse during the decompression process. Even when the force that the screw receives in the axial direction no longer decreases, it may be determined that the resin pressure has been reduced.

<Force detection unit that detects the force that the screw receives in the axial direction>
As described above, the force detection unit that detects the force that the screw receives in the axial direction may include a force detection unit such as a strain gauge or a load cell between the screw and the screw driving unit. Alternatively, a known disturbance load observer may be configured in the servo circuit that drives the screw in the axial direction so as to detect the force received by the screw. Or when driving a movable part with a servomotor, you may make it detect the force which a screw receives based on the drive current of a servomotor. Or when driving a screw with oil pressure, you may make it detect the force which a screw receives based on the pressure value of oil pressure. Or you may make it detect a pressure instead of the force which a screw receives to an axial direction.

<Initial value of resin supply amount command value>
The initial value of the resin supply amount command value F set at the start of operation may be a fixed value according to specifications such as the diameter of the screw 1, or the molded product volume is obtained from the measurement completion position or the like and corresponds to the volume. You may make it supply the amount of resin to perform. The initial value of the supply amount command value F can be stored in advance in the shared RAM 104 that is a nonvolatile memory.

<Calculation of resin supply amount command value>
In calculating the supply amount command value F, if the detected screw resistance is larger than a predetermined target value, the starvation state is dense, so the supply amount command value F is adjusted to be small and the detection is performed. When the screw resistance is smaller than the predetermined target value, the starvation state is sparse, and the supply amount command value F may be adjusted to be increased. Alternatively, PID control may be performed based on the deviation between the detected screw resistance force and a predetermined target value, and the supply amount command value F may be calculated so that the screw resistance force matches the predetermined target value.

<Setting the target value of screw resistance>
As described above, it is possible to control the starvation state to be constant by controlling the detected screw resistance to be a predetermined target value. If adequate starvation is created, screw resistance may be nearly zero. Therefore, the target value of the screw resistance force may be set to zero. Moreover, when the screw resistance force when the appropriate starvation state is formed is known in advance, the value may be set as the target value.
Alternatively, the screw resistance force in a full state may be detected, and a value obtained by multiplying the value by a predetermined coefficient (0 <coefficient <1) may be set as a target value.

<Resin supply amount adjustment unit>
The resin supply amount adjustment unit may adjust the supply amount of the resin material per molding cycle based on the calculated supply amount command value F. For example, if it is a resin material supply part which supplies a resin material using a feed screw like Unexamined-Japanese-Patent No. 6-304967, you may make it control the feed screw rotation amount per 1 molding cycle. Alternatively, the feed screw rotation time per molding cycle may be controlled. Alternatively, the resin supply amount adjusting unit may adjust the supply amount of the resin material per unit time based on the calculated supply command value F in the molding cycle. For example, if it is a resin material supply part which supplies a resin material using a feed screw, you may make it control the rotational speed of the feed screw at the time of resin material supply. At this time, the resin supply adjusting unit may be supplied in correspondence with a predetermined process in the molding cycle. For example, the metering process may be supplied from the start point to the end point, or may be supplied from the start point to the end point of the molding cycle. Alternatively, the supply start time and the supply end time may be set so that the supply time in one molding cycle is a fixed time.

FIG. 2 is a flowchart of a process for adjusting the resin supply amount based on the absolute value of the force received by the screw at an arbitrary time from the completion of the decompression process to the start of screw advancement. Hereinafter, it demonstrates according to each step.
[Step SA01] The initial value of the supply amount command value F is set.
[Step SA02] An injection / pressure holding process is executed.
● [Step SA03] Start weighing.
[Step SA04] The resin supply amount command value F is calculated so that the screw resistance becomes the target value.
[Step SA05] Resin is supplied based on the supply amount command value F.
[Step SA06] When a predetermined amount of resin is weighed, the weighing is completed.
[Step SA07] A decompression step is executed.
[Step SA08] The absolute value of the force received by the screw is detected as the screw resistance force.
[Step SA09] It is determined whether or not the operation is finished. If the operation is not finished, the process returns to Step SA02 to continue the process. If the operation is finished, the process is finished.

FIG. 3 shows the resin supply based on the absolute value of the force received by the screw at any time from the point when the force received by the screw during pressure reduction stops to the point when the force received by the screw during screw advance starts to increase. It is a flowchart of the process which performs quantity adjustment. Hereinafter, it demonstrates according to each step.
[Step SB01] The initial value of the supply amount command value F is set.
[Step SB02] An injection process is executed.
[Step SB03] It is determined whether or not the force received by the screw is increasing. If it is increasing (YES), the process proceeds to Step SB05. If not (NO), the process proceeds to Step SB04. .
[Step SB04] The absolute value of the force received by the screw is detected as the screw resistance force.
[Step SB05] The injection process is completed.
[Step SB06] The pressure holding process is executed.
[Step SB07] The weighing process is started.
[Step SB08] The resin supply amount command value F is calculated so that the screw resistance force becomes a target value.
[Step SB09] Resin is supplied based on the supply amount command value F.
[Step SB10] When a predetermined amount of resin is weighed, the weighing is completed.
[Step SB11] The decompression process is started.
[Step SB12] It is determined whether or not the force received by the screw is reduced. If it is not reduced (NO), the process proceeds to Step SB13, and if it is reduced (YES), it is waited until it is not reduced.
[Step SB13] The absolute value of the force received by the screw is detected as the screw resistance force.

[Step SB14] The pressure reduction is completed.
[Step SB15] It is determined whether or not the operation is finished. If the operation is not finished, the process returns to Step SB02 to continue the process. If the operation is finished, the process is finished.

FIG. 4 is a flowchart of a process for adjusting the resin supply amount based on the screw resistance force excluding the influence of the resin pressure P in front of the screw from the force D received by the screw.
[Step SC01] The initial value of the supply amount command value F is set.
[Step SC02] An injection / pressure holding process is executed.
● [Step SC03] Start weighing.
[Step SC04] The force D received by the screw and the resin pressure P in front of the screw are detected.
[Step SC05] The screw resistance force F is subtracted from the force D received by the screw, the value obtained by multiplying the resin pressure P in front of the screw by the screw cross-sectional area, and the absolute value of the obtained result is obtained.
That is, screw resistance force = | D−P × screw cross-sectional area | is calculated.
[Step SC06] The resin supply amount command value F is calculated so that the screw resistance becomes the target value.
[Step SC07] Resin is supplied based on the resin supply amount F.
[Step SC08] It is determined whether or not the measurement is completed. If the measurement is completed (YES), the process proceeds to Step SC09. If the measurement is not completed (NO), the process proceeds to Step SC04.
[Step SC09] The decompression step is executed.
[Step SC10] It is determined whether or not the operation is finished. If the operation is not finished, the process returns to step SC02 to continue the process. If the operation is finished, the process is finished.

  FIG. 5 is another flowchart of the process for adjusting the resin supply amount based on the screw resistance force excluding the influence of the resin pressure P in front of the screw from the force D received by the screw. In the flowchart of this process, step SC05 of the flowchart shown in FIG. 4 is performed. In step SD05, the screw resistance force calculation unit calculates the detection value of the resin pressure detection unit from the value obtained by dividing the detection value of the force detection unit by the screw cross-sectional area. The difference is that the absolute value of the calculated value is calculated as the screw resistance force, and the details of the processing in the other steps are the same, and the description is omitted.

DESCRIPTION OF SYMBOLS 1 Screw 2 Injection cylinder 4 Hopper 5 Pellet feeder 6 Communication path 7 Rotor with blade M3 Motor F Supply amount command value D Force received by screw

Claims (6)

Injection cylinder, screw, screw forward / backward drive unit for driving the screw in the forward / backward direction, force detection unit for detecting the force received by the screw in the axial direction, and resin material supply for supplying the resin material into the injection cylinder In an injection molding machine having a part,
A screw resistance force calculation unit for calculating a screw resistance force based on a detection value of the force detection unit;
An injection molding machine comprising: a resin supply amount adjusting unit that decreases a resin supply amount of the resin material supply unit as the screw resistance increases.   2. The screw resistance calculation unit according to claim 1, wherein the screw resistance calculation unit calculates an absolute value of a detection value of the force detection unit at an arbitrary time from the completion of the decompression process to the start of screw advancement as a screw resistance. Injection molding machine.   The screw resistance force calculation unit may calculate the force at any time from when the detection value of the force detection unit does not decrease during decompression to when the detection value of the force detection unit starts to increase during screw advancement. The injection molding machine according to claim 1, wherein an absolute value of a detection value of the detection unit is calculated as a screw resistance force.   A resin pressure detection unit that detects a resin pressure in front of the screw, and the screw resistance calculation unit subtracts a value obtained by multiplying a detection value of the resin pressure detection unit by a screw cross-sectional area from a detection value of the force detection unit. 2. The injection molding machine according to claim 1, wherein an absolute value of the calculated value is calculated as a screw resistance force.   A resin pressure detection unit that detects a resin pressure in front of the screw, and the screw resistance force calculation unit subtracts the detection value of the resin pressure detection unit from a value obtained by dividing the detection value of the force detection unit by a screw cross-sectional area. 2. The injection molding machine according to claim 1, wherein an absolute value of the calculated value is calculated as a screw resistance force.   The resin supply amount adjusting unit adjusts the resin supply amount of the resin material supply unit so that the screw resistance becomes a predetermined target value. The injection molding machine described.

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