JP6774784B2 - Injection molding machine and injection molding method - Google Patents

Description

The present invention relates to an injection molding machine and an injection molding method in which one weighing operation is followed by a plurality of injection operations.

Patent Document 1 discloses a conventional injection molding machine. This injection molding machine uses a mold having a plurality of cavities having different shapes and sizes, performs one weighing operation, and then performs an injection operation for each of the plurality of cavities.

In this injection molding machine, the resin pressure of the injection cylinder and the resin passage leading to it is reduced to zero by cutting the current of the servo motor that drives the screw between one injection operation and the subsequent injection operation. The position where the screw is pushed back by the resin at this time is set as the injection start position in the next injection operation.

Japanese Unexamined Patent Publication No. 2004-155071

In the injection molding machine, the next injection start position is set by reducing the torque of the screw to zero and releasing the resin pressure as described above. However, in the configuration in which the injection operation is performed a plurality of times for one weighing operation, the state inside the injection cylinder is different, for example, the amount of resin in the injection cylinder and the heating time of the resin are different at each injection operation. May make a difference. Therefore, when the injection start position is determined by pushing back with the resin, the resin density in the injection cylinder during each injection operation may vary, and the quality of the molded product may become unstable. ..

Therefore, an object of the present invention is to provide an injection molding machine and an injection molding method capable of suppressing variations in resin density in an injection cylinder in a plurality of injection operations performed following one weighing operation.

In order to achieve the above object, the injection molding machine of one aspect of the present invention includes an injection cylinder, a screw housed in the injection cylinder, and a drive unit for rotating and moving the screw forward and backward in the injection cylinder. In an injection molding machine having, the drive unit rotates and retracts the screw so as to measure and store a plurality of injection amounts of resin in the space in front of the screw in the injection cylinder. A unit, an injection control unit that advances the screw in a plurality of times by the drive unit so that an injection operation of ejecting an injection amount of resin from the resin stored in the front space is performed a plurality of times. The screw is operated by the drive unit so that the pressure of the resin stored in the front space becomes a reference pressure value over the guaranteed injection pressure time between one injection operation by the injection control unit and the next injection operation. It has an injection pressure guarantee control unit that adjusts the position in the front-rear direction, and the injection operation by the injection control unit is an operation of injecting one injection amount of resin from the resin stored in the front space. And, the position of the screw in the front-rear direction by the drive unit so that the pressure of the resin stored in the front space after the injection of the injection amount of the resin for one injection becomes the holding pressure value over the holding pressure time. It is an operation of adjusting the above, and the reference pressure value is smaller than the holding pressure value and larger than 0 .

According to the present invention, the pressure of the resin stored in the space in front of the screw in the injection cylinder between the injection operation of one of the injection operations performed a plurality of times and the subsequent injection operation is the injection pressure guaranteed time. The position of the screw in the front-rear direction is adjusted by the drive unit so that the reference pressure value is obtained over the entire range. By doing so, the resin pressure in the injection cylinder becomes uniform in each of the plurality of injection operations, so that unevenness in the resin state in the injection cylinder can be suppressed and the resin density can be made uniform in each injection operation. it can.
In addition, the injection operation by the injection control unit is an operation of injecting one injection amount of resin from the resin stored in the front space, and the front after the one injection amount of resin is injected. This is an operation of adjusting the position of the screw in the front-rear direction by the drive unit so that the pressure of the resin stored in the space becomes the holding pressure value over the holding pressure time. By doing so, it is possible to suppress insufficient filling of the resin in each injection operation.

In the present invention, the suckback operation is performed between one injection operation by the injection control unit and the next injection operation, starting from the position of the screw at the end of the injection pressure guarantee time. It is preferable to further have a suckback control unit for retracting the screw by the drive unit. By doing so, it is possible to suppress resin dripping from the nozzle of the injection cylinder by the suckback operation. Further, by keeping the amount of retreat of the screw for the suckback operation constant, the resin density in the injection cylinder can be made uniform in each of the plurality of injection operations even after the suckback operation.

In the present invention, a plurality of pressure values having different sizes are set as the reference pressure value.
The injection pressure guarantee control unit is in the front-rear direction of the screw so that the pressure of the resin stored in the front space is sequentially changed from the larger pressure value among the plurality of pressure values to the smaller pressure value in the injection pressure guarantee time. It is preferable to adjust the position of .

In order to achieve the above object, another aspect of the injection molding method of the present invention is an injection cylinder, a screw housed in the injection cylinder, and a drive for rotating and moving the screw forward and backward in the injection cylinder. This is an injection molding method used in an injection molding machine having a portion, and the screw is operated by the drive portion so as to measure and store a plurality of injection amounts of resin in the space in front of the screw in the injection cylinder. The screw is divided into a plurality of times by the drive unit so as to perform a measurement control step of retreating while rotating and an injection operation of injecting one injection amount of resin from the resin stored in the front space. The pressure of the resin accumulated in the front space becomes the reference pressure value over the guaranteed injection pressure time between the injection control step to advance the injection control step and one injection operation in the injection control step and the next injection operation. the, seen including and a injection pressure assurance control step of adjusting the longitudinal position of the screw by the drive unit, wherein the injection process in the injection control step, one time of the injection from said pooled in the front space resin The drive unit so that the operation of injecting an amount of resin and the pressure of the resin accumulated in the front space after injection of the injection amount of the one injection amount becomes the holding pressure value over the holding time. This is an operation of adjusting the position of the screw in the front-rear direction, wherein the reference pressure value is smaller than the holding pressure value and larger than 0 .

According to the present invention, the pressure of the resin stored in the space in front of the screw in the injection cylinder between the injection operation of one of the injection operations performed a plurality of times and the subsequent injection operation is the injection pressure guaranteed time. The position of the screw in the front-rear direction is adjusted by the drive unit so that the reference pressure value is obtained over the entire range. By doing so, the resin pressure in the injection cylinder becomes equal in each of the multiple injection operations, so that unevenness in the resin state in the injection cylinder can be suppressed and the resin density can be made uniform in each injection operation. Can be done.

According to the present invention, it is possible to suppress variations in the resin density in the injection cylinder in a plurality of injection operations performed following one weighing operation. As a result, it is possible to prevent the quality of the molded product from becoming unstable.

It is a figure which shows the schematic structure of the injection molding machine which concerns on one Embodiment of this invention. It is a figure which shows an example of the setting screen of the condition value of the operation in the injection molding machine of FIG. It is a figure explaining an example (with a suckback operation) of the operation flow in the injection molding machine of FIG. It is a figure explaining another example (without a suckback operation) of the operation flow in the injection molding machine of FIG.

Hereinafter, the injection molding machine according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a diagram showing a schematic configuration of an injection molding machine according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a screen for setting operation condition values in the injection molding machine of FIG. 3 and 4 are diagrams for explaining an example of the flow of operation in the injection molding machine of FIG. 1 (with / without suckback operation).

As shown in FIG. 1, the injection molding machine 1 has an injection unit 10 and a control unit 30.

The injection unit 10 includes an injection cylinder 11, a screw 12, a rotation control servomotor 13, a rotation control timing belt 14, a screw pulley 15, a position control servomotor 16, and a position control timing belt 17. It has a ball screw mechanism 18, a rotation detection encoder 19, a position detection encoder 20, and a load cell 21.

The injection cylinder 11 is formed in a tubular shape having a nozzle 11a at one end, and is provided with a heater (not shown) on the outer peripheral surface thereof. The screw 12 is housed in the injection cylinder 11 so as to be rotatable and movable in the front-rear direction (that is, to be able to move forward and backward). In the present specification, the nozzle 11a side of the injection cylinder 11 of FIG. 1 is the front side, and the opposite side is the rear side.

The rotation control servomotor 13 is a drive unit that rotates the screw 12. The rotation of the output pulley 13a of the rotation control servomotor 13 is transmitted to the screw pulley 15 coaxially fixed to the screw 12 via the rotation control timing belt 14. As a result, the screw 12 is rotated about the shaft.

The position control servomotor 16 is a drive unit that moves the screw 12 back and forth. The rotation of the output pulley 16a of the position control servomotor 16 is transmitted to the screw shaft pulley 18b coaxially fixed to the screw shaft 18a of the ball screw mechanism 18 via the position control timing belt 17. As a result, the screw shaft 18a is rotated about the shaft. Then, the rotation of the screw shaft 18a causes the nut portion 18c screwed via the ball (not shown) to move in the axial direction (that is, the front-rear direction). Along with the movement of the nut portion 18c, the screw 12 fixed to the nut portion 18c is also moved in the front-rear direction. When the screw 12 is moved in the front-rear direction by the position control servomotor 16, the pressure applied to the resin stored in the position of the screw 12 and the front space E of the screw 12 in the injection cylinder 11 (hereinafter, simply ". Resin pressure P ”) is adjusted.

The rotation detection encoder 19 detects the rotation position of the rotation control servomotor 13, and the control unit 33 of the control unit 30, which will be described later, detects the rotation speed R of the screw 12 based on this rotation position. The position detection encoder 20 detects the rotational position of the position control servomotor 16, and the control unit 33 detects the position L and the moving speed V of the screw 12 in the front-rear direction based on the rotational position. The load cell 21 detects the pressure applied to the screw 12, and the control unit 33 detects the resin pressure P based on this pressure.

The control unit 30 includes a setting storage unit 31, a display operation unit 32, a control unit 33, a rotation control servo amplifier 34, and a position control servo amplifier 35.

The setting storage unit 31 is configured to include, for example, a rewritable storage medium such as a hard disk device or a non-volatile memory. The setting storage unit 31 stores (that is, stores) condition values such as the rotation speed R, the position L, and the moving speed V of the screw 12 during various operations, and the resin pressure P in the injection cylinder 11. Various operations include (1) a weighing operation in which a plurality of injection amounts of resin are weighed and stored in the front space E in the injection cylinder 11, and (2) a post-weighing pressure correction operation in which the resin pressure P is corrected after the measuring operation. (3) Injection operation of injecting and holding pressure of one injection amount of resin from the resin stored in the front space E, (4) Injection pressure guaranteed time Ts between one injection operation and the next injection operation. An injection pressure guarantee operation for holding the resin pressure P to be a reference pressure value Ps over a period of time, (5) a suckback operation executed as an option after the injection pressure guarantee operation, and the like are included. In the setting storage unit 31, the setting value is written by the display operation unit 32 described later, and the setting value is read out by the control unit 33 and used in various operations.

In the present embodiment, the setting storage unit 31 has a condition value for the weighing operation.
(A) Weighing retreat position Xm [mm], which is the retreating position of the screw 12 when weighing is completed,
(B) Weighing rotation speed Rm [rpm] of the screw 12 from the most advanced position 0 of the screw 12 to the weighing backward position Xm,
(C) Execution of reweighing according to the measurement pressure value Pm [MPa], which is the pressure value applied to the resin stored in the front space E from the position 0 to the measurement retreat position Xm, and (d) the position of the screw 12. The set value for the weighing execution determination position Xe [mm] for determining the necessity is stored.

Further, the setting storage unit 31 has a condition value for the pressure correction operation after weighing.
(E) Post-weighing correction pressure value Pc [MPa], which is the pressure value applied to the resin stored in the front space E after the weighing operation, and (f) Post-weighing correction time Tc [s, which is the period for holding the pressure value. ] Is stored.

Further, the setting storage unit 31 contains a condition value for injection operation.
(G) Injection section Li (mm) for performing injection operation,
(H) Injection moving speed of screw 12 in injection section Li Vi [mm / s],
(I) Primary pressure value Pi [MPa], which is the upper limit of the pressure applied to the resin during the injection operation.
(J) Injection stroke Di [mm], which is the stroke amount of the screw 12 in one injection operation.
(K) Holds the holding pressure value Ph [MPa], which is the pressure value applied to the resin stored in the front space E after the cavity of the mold is filled with the resin by injection, and (l) the pressure value. The set value for the holding pressure time Th [s], which is the period, is stored.

It is possible to divide the injection section Li into a plurality of sections (1st speed, 2nd speed, ..., N speed) and set different injection movement speeds Vi in each section. Further, the holding pressure time Th can be divided into a plurality of times (1, 2, ..., N), and different holding pressure values Ph can be set in each time.

Further, the setting storage unit 31 has a condition value for the injection pressure guarantee operation.
(M) Holds the reference pressure value Ps [MPa], which is the pressure value applied to the resin stored in the front space E, and (n) and the pressure value between one injection operation and the next injection operation. The set value for the injection pressure guarantee time Ts [s], which is the period to be used, is stored. The reference pressure value Ps is preferably smaller than the holding pressure value Ph.

Further, the setting storage unit 31 has a condition value for the sackback operation.
The set values for (o) the sackback stroke Ds [mm], which is the stroke amount of the screw 12 in the sackback operation, and (p) the sackback movement speed Vs [mm / s] are stored.

The sackback operation is an optional operation, and the sackback operation can be omitted by setting the sackback stroke Ds to 0.

The display operation unit 32 includes, for example, a display unit 32a composed of a flat panel display such as a liquid crystal display or an organic EL display, and an operation unit 32b provided with a touch panel arranged so as to overlap the display surface of the display unit 32a. Have. The display unit 32a displays various information such as numerical values, images, and graphs, and various operation switch images such as keyboards, numeric keys, check boxes, selection lists, and operation buttons. Touch operations are input to the touch panel of the operation unit 32b by a user such as an operator using an operating body such as a finger or a touch operation pen.

In the display operation unit 32, the software operation switch is realized by combining the operation switch image displayed on the display unit 32a and the touch panel of the operation unit 32b. Hereinafter, touch operation of a portion corresponding to the operation switch image displayed on the display unit 32a on the touch panel of the operation unit 31b is simply referred to as "touch operation". The operation unit 32b includes a mouse, and various operations may be performed by the mouse.

FIG. 2 shows an example of the setting screen G1 displayed on the display unit 32a. The setting screen G1 is a screen for displaying and inputting the setting values of the condition values of various operations. When the setting value display location of each of the condition values (a) to (p) is touch-operated in the state where the setting screen G1 is displayed on the display unit 32a, the display operation unit 32 overlaps the setting screen G1 with the numeric keypad. (Not shown) is displayed. Then, when the numeric keypad is touch-operated and a value is input, the display operation unit 32 sends the input value to the setting storage unit 31 and stores it as a setting value of the condition value.

The control unit 33 is composed of a microcomputer or the like. The control unit 33 generates control signals in various operations, outputs the control signals to the rotation control servo amplifier 34 and the position control servo amplifier 35, and causes the rotation control servo motor 13 and the position control servo motor 16 to operate. Control.

As a weighing operation, the control unit 33 reads out the measuring rotation speed Rm, the measuring pressure value Pm, and the measuring backward position Xm from the setting storage unit 31. Then, the control unit 33 generates a control signal so that the screw 12 retracts to the weighing retreat position Xm while the screw 12 rotates at the weighing rotation speed Rm and the resin pressure P becomes the weighing pressure value Pm ( Weighing control step).

As the post-weighing pressure correction operation, the control unit 33 reads the post-weighing correction time Tc and the post-weighing correction pressure value Pc from the setting storage unit 31. Then, the control unit 33 generates a control signal for adjusting the position of the screw 12 in the front-rear direction so that the resin pressure P becomes the post-weighing correction pressure value Pc over the post-weighing correction time Tc (post-weighing pressure correction control step). ).

As an injection operation, the control unit 33 sets the injection section Li, the injection moving speed Vi, the primary pressure value Pi, the injection stroke Di, the measurement execution determination position Xe, the holding pressure value Ph, and the holding time Th from the setting storage unit 31. read out. Then, the control unit 33 generates a control signal so that the screw 12 advances the distance indicated by the injection stroke Di at the injection movement speed Vi while preventing the resin pressure P from exceeding the primary pressure value Pi. , The control unit 33 generates a control signal for adjusting the position of the screw 12 in the front-rear direction so that the resin pressure P becomes the holding pressure value Ph over the holding pressure time Th (injection control step). Further, when the screw 12 is behind the weighing execution determination position Xe, the control unit 33 waits for the end of the injection pressure guarantee operation and the suckback operation, which will be described later, and then performs the next injection operation, and the screw 12 determines the measurement execution. When the position Xe or the front side thereof, the weighing operation is performed. In the next injection operation, the position of the screw 12 at the end of the immediately preceding sackback operation is set as the injection start position, and when the sackback operation is omitted, the position of the screw 12 at the end of the immediately preceding injection pressure guarantee operation is set as the injection start position. It is said.

As an injection pressure guarantee operation, the control unit 33 reads out the injection pressure guarantee time Ts and the reference pressure value Ps from the setting storage unit 31. Then, the control unit 33 adjusts the position of the screw 12 in the front-rear direction so that the resin pressure P becomes the reference pressure value Ps over the injection pressure guaranteed time Ts between one injection operation and the next injection operation. Generate a control signal to be used (injection pressure guaranteed control step).

As a sackback operation, the control unit 33 reads the sackback movement speed Vs and the sackback stroke Ds from the setting storage unit 31. Then, the control unit 33 sets the control signal so that the screw 12 retracts the distance indicated by the sackback stroke Ds at the sackback movement speed Vs, starting from the position of the screw 12 at the end of the injection pressure guarantee time Ts. Generate (sackback control step).

In the various operations described above, the control unit 33 determines the rotation speed R of the screw described above based on the rotation position output A1 of the rotation detection encoder 19, the rotation position output A2 of the position detection encoder 20, and the pressure output A3 of the load cell 21. , Movement speed V and position L, and resin pressure P are feedback-controlled.

The control unit 33 operates as various functional units such as a measurement control unit, a post-measurement pressure correction control unit, an injection control unit, an injection pressure guarantee control unit, and a sackback control unit.

Next, an example of the injection molding cycle executed by the injection molding machine 1 described above will be described with reference to FIG.

The injection molding machine 1 first displays the setting screen G1 on the display unit 32a of the display operation unit 32, and the setting values of the condition values (a) to (p) are input from the operation unit 32b, and each set value is input. It is stored in the setting storage unit 31.

Then, as shown in FIG. 3, the injection molding machine 1 executes one injection molding cycle including a weighing operation, a post-weighing pressure correction operation, a plurality of injection operations, and a plurality of injection pressure guarantee operations a plurality of times.

That is, the injection molding machine 1 executes the weighing operation 1 to rotate the screw 12 at the weighing rotation speed Rm and retract the screw 12 to the weighing retreat position Xm while making the resin pressure P the measuring pressure value Pm. Let me. As a result, the resin for a plurality of injection amounts is weighed and stored in the front space E of the screw 12 in the injection cylinder 11.

Next, the injection molding machine 1 executes the post-weighing pressure correction operation 1 and adjusts the position of the screw 12 in the front-rear direction to adjust the resin pressure P to the post-weighing correction pressure value Pc over the post-weighing correction time Tc. To be. As a result, unevenness in the resin state in the injection cylinder 11 is suppressed and the resin density becomes uniform. Further, if necessary, the injection molding machine 1 opens the mold to take out the molded product after each measurement post-pressure correction operation, closes the mold, and communicates the nozzle 11a of the injection cylinder 11 with the cavity again. ..

Next, the injection molding machine 1 executes the injection operation 1 to advance the screw 12 at the injection moving speed Vi by the distance indicated by the injection stroke Di while preventing the resin pressure P from exceeding the primary pressure value Pi. Let me. Further, the injection molding machine 1 adjusts the position of the screw 12 in the front-rear direction so that the resin pressure P becomes the holding pressure value Ph over the holding pressure time Th. As a result, after the resin is injected into the cavity of the mold (not shown), the resin is surely filled in the cavity by the holding pressure.

Here, since the screw 12 is behind the weighing execution determination position Xe at the end of the injection operation 1, the injection molding machine 1 subsequently executes the injection pressure guarantee operation 1. That is, the injection molding machine 1 adjusts the position of the screw 12 in the front-rear direction between the injection operation 1 and the subsequent injection operation 2, so that the resin pressure P becomes the reference pressure value Ps over the injection pressure guaranteed time Ts. To be. As a result, unevenness of the resin pressure P is suppressed in the injection cylinder 11 and the resin density becomes uniform.

Next, the injection molding machine 1 executes the sackback operation 1 to retract the screw 12 at the sackback moving speed Vs by the distance indicated by the sackback stroke Ds. As a result, resin dripping from the nozzle 11a of the injection cylinder 11 can be suppressed.

Further, when the injection pressure guarantee operation 1 is completed, the injection molding machine 1 opens the mold to take out the molded product, closes the mold, and communicates the nozzle 11a of the injection cylinder 11 with the cavity again.

Then, in the same manner as described above, the injection molding machine 1 sequentially performs injection operation 2, injection pressure guarantee operation 2, sackback operation 2, ..., Injection operation n-1, injection pressure guarantee operation n-1, and sackback. The operation n-1 and the injection operation n are executed.

Since the screw 12 is in front of the weighing execution determination position Xe at the end of the injection operation n, the injection molding machine 1 ends one injection molding cycle. Then, the next injection molding cycle is started, and the weighing operation 2 included in the injection molding cycle is executed.

From this point onward, a plurality of injection molding cycles are executed in the same manner.

Although the injection molding cycle including the suckback operation has been described above, the injection molding cycle not including the suckback operation may be executed as shown in FIG.

As described above, according to the injection molding machine 1 of the present embodiment, the screw 12 in the injection cylinder 11 is between the injection operation of one of the injection operations performed a plurality of times and the subsequent injection operation. The position control servomotor 16 adjusts the position of the screw 12 in the front-rear direction so that the pressure of the resin (resin pressure P) stored in the front space E becomes the reference pressure value Ps over the guaranteed injection pressure time Ts. By doing so, the resin pressure P in the injection cylinder 11 becomes uniform in each of the plurality of injection operations, so that unevenness in the resin state in the injection cylinder 11 is suppressed and the resin density is increased in each injection operation. It can be aligned.

Further, the position control servomotor 16 is used to perform the suckback operation with the position of the screw 12 at the end of the injection pressure guarantee time Ts as the start position between one injection operation and the next injection operation. Retreat 12 By doing so, it is possible to suppress the resin dripping from the nozzle 11a of the injection cylinder 11 by the suckback operation. Further, by keeping the amount of retreat of the screw 11 for the suckback operation constant, the resin density in the injection cylinder 11 can be made uniform in each of the plurality of injection operations even after the suckback operation.

Further, in the injection operation, the position control servomotor 16 is used in the front-rear direction of the screw 12 so that the resin pressure P after injection of the resin of one injection amount becomes the holding pressure value Ph over the holding time Th. Adjust the position. By doing so, it is possible to suppress insufficient filling of the resin in each injection operation.

Therefore, according to the injection molding machine 1 of the present embodiment, it is possible to suppress variations in the resin density in the injection cylinder 11 in a plurality of injection operations performed after one weighing operation. As a result, it is possible to prevent the quality of the molded product from becoming unstable.

In the above-described embodiment, one pressure value is set as the reference pressure value Ps, but the present invention is not limited to this. In addition to this, a plurality of pressure values having different sizes (for example, three pressure values 30 MPa, 20 MPa, 10 MPa) are set as the reference pressure value Ps, and the pressure of the resin stored in the front space E (resin pressure P). ) May sequentially adjust the position of the screw 12 in the front-rear direction by the position control servomotor 16 so that the pressure value of the plurality of pressure values is sequentially changed from the larger pressure value to the smaller pressure value in the injection pressure guarantee time Ts. .. By doing so, the resin pressure P in the injection cylinder 11 is gradually lowered, so that the degree of change in the state in the injection cylinder 11 is smaller than when the pressure is changed at once, and therefore, in the injection cylinder 11. The unevenness of the state can be further suppressed, and the resin density in the injection cylinder 11 can be made more uniform in each injection operation.

Although the present embodiment of the present invention has been described above, the present invention is not limited to these examples. As long as the gist of the present invention is provided, a person skilled in the art appropriately adding, deleting, or changing the design of the above-described embodiment, or combining the features of the embodiment as appropriate is also present. Included in the scope of the invention.

1 ... Injection molding machine, 10 ... Injection unit, 11 ... Injection cylinder, 11a ... Nozzle, 12 ... Screw, 13 ... Rotation control servo motor (drive unit), 13a ... Output pulley, 14 ... Rotation control timing belt, 15 ... Screw pulley, 16 ... Position control servo motor (drive unit), 16a ... Output pulley, 17 ... Position control timing belt, 18 ... Ball screw mechanism, 18a ... Screw shaft, 18b ... Shaft pulley, 18c ... Nut part, 19 ... Rotation detection encoder, 20 ... Position detection encoder, 21 ... Load cell, 30 ... Control unit, 31 ... Setting storage unit, 32 ... Display operation unit, 32a ... Display unit, 32b ... Operation unit, 33 ... Control unit (weighing) Control unit, injection control unit, injection pressure guarantee control unit, sackback control unit), 34 ... rotation control servo amplifier, 35 ... position control servo amplifier, A1 ... rotation position output, A2 ... rotation position output, A3 ... pressure Output, E ... front space, G1 ... setting screen, R ... screw rotation speed, L ... screw position, V ... screw moving speed, P ... resin pressure in injection cylinder, Xm ... weighing retreat position, Rm ... weighing Rotation speed, Pm ... Weighing pressure value, Xe ... Weighing execution judgment position, Pc ... Post-weighing correction pressure value, Tc ... Post-weighing correction time, Li ... Injection section, Vi ... Injection movement speed, Pi ... Primary pressure value, Di ... Injection stroke, Ph ... Holding pressure value, Th ... Holding time, Ps ... Reference pressure value, Ts ... Injection pressure guaranteed time, Ds ... Suckback stroke, Vs ... Suckback movement speed.

Claims (4)

An injection molding machine having an injection cylinder, a screw housed in the injection cylinder, and a drive unit for rotating and moving the screw forward and backward in the injection cylinder.
A metering control unit that rotates and retracts the screw by the drive unit so that the resin of a plurality of injection amounts is measured and stored in the space in front of the screw in the injection cylinder.
An injection control unit that advances the screw in a plurality of times by the drive unit so as to perform an injection operation for injecting one injection amount of resin from the resin stored in the front space a plurality of times.
The screw is operated by the drive unit so that the pressure of the resin stored in the front space becomes a reference pressure value over the guaranteed injection pressure time between one injection operation by the injection control unit and the next injection operation. Has an injection pressure guarantee control unit that adjusts the position of the
The injection operation by the injection control unit is an operation of injecting one injection amount of resin from the resin stored in the front space, and an operation of injecting one injection amount of resin into the front space after injection of the one injection amount of resin. This is an operation of adjusting the position of the screw in the front-rear direction by the driving unit so that the pressure of the stored resin becomes the holding pressure value over the holding time.
The injection molding machine , wherein the reference pressure value is smaller than the holding pressure value and larger than 0 . The drive unit performs a suckback operation between one injection operation by the injection control unit and the next injection operation, starting from the position of the screw at the end of the injection pressure guarantee time. The injection molding machine according to claim 1, further comprising a suckback control unit for retracting the screw. As the reference pressure value, a plurality of pressure values having different sizes are set.
The injection pressure guarantee control unit is in the front-rear direction of the screw so that the pressure of the resin stored in the front space is sequentially changed from the larger pressure value among the plurality of pressure values to the smaller pressure value in the injection pressure guarantee time. The injection molding machine according to claim 1 or 2 , wherein the position of the injection molding machine is adjusted . An injection molding method used in an injection molding machine having an injection cylinder, a screw housed in the injection cylinder, and a drive unit for rotating and moving the screw forward and backward in the injection cylinder.
A measurement control step in which the screw is rotated and retracted by the drive unit so as to measure and store a plurality of injection amounts of resin in the space in front of the screw in the injection cylinder.
An injection control step in which the screw is advanced in a plurality of times by the drive unit so as to perform an injection operation of injecting one injection amount of resin from the resin stored in the front space a plurality of times.
The screw is operated by the drive unit so that the pressure of the resin stored in the front space becomes a reference pressure value over the guaranteed injection pressure time between one injection operation and the next injection operation in the injection control step. seen containing an injection pressure assurance control step of adjusting the longitudinal position, of,
The injection operation in the injection control step is an operation of injecting one injection amount of resin from the resin stored in the front space, and an operation of injecting one injection amount of resin into the front space after injection of the one injection amount of resin. This is an operation of adjusting the position of the screw in the front-rear direction by the driving unit so that the pressure of the stored resin becomes the holding pressure value over the holding time.
The injection molding method , wherein the reference pressure value is smaller than the holding pressure value and larger than 0 .

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