JP2001260176A - Automatic purging method and apparatus for motor- driven injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly discharge a resin residual material to the outside from the inside of a barrel and to reduce labor of an operator by avoiding excess load on a motor for rotating an injection screw and preventing its malfunction from being generated. SOLUTION: The injection screw inserted in the barrel from which an injection nozzle is removed is rotated at the most advanced position by means of a feeding servo motor 9 (the motor for rotation) and the rate of loading is monitored by means of an electric current comparator 12 (a load monitoring means) and when the rate of loading exceeds a set value of overload rate of a loading rate setting tool 10, after the injection screw is sucked back by means of an injection servo motor 5 (the motor for movement), it is moved to the most advanced position and thereafter, an automatic purging motion consisting of rotation of the injection screw at the most advanced position, sucking back and movement to the most advanced position is repeatedly performed until the rate of loading of the feeding servo motor 9 becomes to the set value of overload rate or lower to discharge the resin residual material in the barrel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic purging method and an automatic purging apparatus for automatically discharging resin residue remaining in a barrel of an injection unit to the outside at the end of resin injection molding in an electric injection molding machine. It is about.

[0002]

2. Description of the Related Art In an injection molding machine, particularly when a thermosetting resin is used, when molding is interrupted for a certain period of time at the end of molding or during molding, the resin remaining in the barrel in preparation for the next shot. It is necessary to perform an operation (purge operation) of discharging all the material (resin residual material) from the inside of the barrel. Conventionally,
The purging operation was manually performed according to the following procedure. That is, (1) After the injection unit is retracted to the last retreat position where the injection nozzle is separated from the mold, the injection screw is operated to perform the injection operation to move to the most advanced position, and the molten resin accumulated at the tip of the injection nozzle is injected. I do. (2) The injection screw is retracted to the retreat end position, and is left until the substantial temperature of the barrel becomes about the room temperature set in the setting device (thereby 1 to 2 pitches of the tip side groove portion of the injection screw). The resin hardens in the barrel over a length corresponding to. (3) Remove the injection nozzle from the barrel, and place a container below the barrel to receive the resin residue from the barrel.
(4) The injection screw is advanced to the most advanced position by a manual operation and rotated afterward (this causes the powdery resin residue in the rear half of the screw to be transferred to the front of the screw, and the tip of the injection screw is moved by the advancing pressure. The semi-molten or solidified resin residue is extruded). (5) The rotation of the injection screw is continued until no powdery resin remains after the semi-melted or solidified resin remains. (6) Thereafter, the operator removes the resin fixed to the screw tip using a tool such as a copper bar, and removes the resin adhering to the nozzle mounting screw portion of the barrel by blowing air. In addition, the resin remaining material removed from the barrel and stored in the container is disposed of.

[0003] In the purging operation according to the above procedure, when the resin residue hardened in the operation of the step (4) is not discharged, the injection screw is empirically operated to manually remove the injection screw by 10 to 15 mm.
Once retracted, move forward and then rotate the injection screw. If the resin residue is still not discharged,
After repeating the backward and forward movements of the injection screw, the injection screw is rotated to check the discharge of resin residue.

[0004]

In an electric injection molding machine, an overload is applied to an electric servomotor as a rotating electric motor for rotating the injection screw when the injection screw is rotated, depending on the solidification state of the resin residual material. However, there is a problem that the injection screw may not be able to rotate because the operation is sometimes instantaneously malfunctioned due to the maximum overload.

The present invention has been made in view of the above problems, and it is possible to reliably discharge resin residue remaining in an injection screw and a barrel to the outside by automatic operation of rotation and forward / backward movement of the injection screw. It is an object of the present invention to provide an automatic purging method and an automatic purging apparatus capable of reducing labor of an operator. Another object of the present invention is to prevent an overload from being applied to a motor for rotating an injection screw, prevent the occurrence of operation failure of the motor, and smoothly remove resin residue remaining in the injection screw and barrel. It is an object of the present invention to provide an automatic purging method and an automatic purging apparatus which can discharge the waste water to the drain.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, an injection screw inserted into a barrel from which an injection nozzle has been removed is rotated by a rotating electric motor at its most advanced position. When the load factor of the rotary motor exceeds the preset overload factor set value, the injection screw is sucked back by the preset stroke by the moving motor, and then moved to the most advanced position. Injection screw rotation in the forward position, suckback,
The automatic purging operation of moving to the most advanced position is repeatedly performed until the load factor of the rotating electric motor becomes equal to or less than the overload factor set value, and the resin remaining material in the barrel is discharged. .

In the automatic purging method having this configuration, when the injection screw is rotated by the rotating electric motor at the most advanced position, resin residue remaining in the barrel and the injection screw is removed from the barrel from which the injection nozzle is removed. Is discharged from At this time, when the load factor of the rotating motor exceeds a preset overload factor set value, the injection screw is sucked back by the preset stroke by the moving motor and then moved to the most advanced position. Thereafter, the automatic purge operation of the rotation of the injection screw at the most advanced position, suckback, and movement to the most advanced position is repeatedly performed until the load factor of the rotating electric motor becomes equal to or less than the overload factor set value. Thereby, the resin remaining material in the barrel is discharged. Therefore, during the discharge operation of the resin residual material from the inside of the barrel, there is no possibility that an excessive load acts on the rotation motor of the injection screw to cause operation failure, and the discharge operation is performed smoothly and reliably. .

According to a second aspect of the present invention, the injection screw inserted into the barrel from which the injection nozzle has been removed is rotated by the rotating motor at the most advanced position, and the injection screw is rotated from the most advanced position during rotation of the injection screw. The presence or absence of the backward movement is monitored, and when the injection screw starts the backward movement, the injection screw is sucked back by a predetermined stroke by the moving motor and then moved to the most advanced position, and thereafter the injection at the most advanced position is performed. A structure in which the screw is rotated, sucked back, and the automatic purging operation of moving to the most advanced position is repeatedly performed until there is no retreating movement during rotation of the injection screw at the most advanced position, and the resin remaining material in the barrel is discharged. It is what it was.

In the automatic purging method having this configuration, when the injection screw is rotated by the rotating electric motor at the most advanced position, resin residue remaining in the barrel and the injection screw is removed from the barrel from which the injection nozzle is removed. Is discharged from At this time, when the injection screw starts retreating from the most advanced position due to the resistance of the residual resin material, the injection screw is sucked back by a preset stroke by the moving motor and then moved to the most advanced position. Since then
By rotating the injection screw at the most advanced position, sucking back, and automatically purging the movement of the injection screw to the most advanced position, the injection screw is repeatedly performed until there is no retreating during rotation at the most advanced position. Resin remaining material in the barrel is discharged. Therefore, even in this automatic purging method, during the operation of discharging the resin residue from the barrel,
The discharge operation can be performed smoothly and reliably without the occurrence of operation failure due to excessive load acting on the rotation motor of the injection screw.

[0010] In the automatic purging method according to claim 1,
When the injection screw is rotated at the most advanced position, if the load factor of the rotating electric motor exceeds an overload factor set value, the injection screw is stopped to perform an automatic purging operation. In the automatic purging method according to the above, when the injection screw starts retreating from the most advanced position during rotation of the injection screw at the most advanced position, the rotation of the injection screw is stopped to perform the automatic purging operation. Since the load factor of the rotating electric motor is quickly reduced, the above-described discharge operation is executed more smoothly, reliably and safely without exerting an excessive force on the rotating electric motor.

[0011] In the automatic purging method according to any one of claims 1 to 4, if the resin remaining material is a thermosetting resin, when molding is completed or when molding is interrupted for a predetermined time during molding. In addition, even for a thermosetting resin that easily adheres to an injection screw or a barrel, resin residue can be easily discharged from the barrel.

According to a sixth aspect of the present invention, the injection screw inserted into the barrel provided with the detachable injection nozzle is rotated by the rotating motor at its most advanced position, and is moved to the most advanced position by the moving motor. An automatic purging device of an electric injection molding machine, which performs an automatic purging operation to repeat an operation of moving forward after sucking back in a state of stopping rotation and discharging resin residue in the barrel, A current detector that detects a load current of the rotating motor, and whether a load factor of the rotating motor based on the load current detected by the current detector exceeds an overload factor set by a load factor setting device. Load control means for determining whether the load factor has exceeded the overload rate, and control means for instructing the automatic purging operation; and Operated by a command from, it is obtained by a configuration in which a driving means for actuating the moving electric motor and the rotary electric motor.

In the automatic purging apparatus having this configuration, when the injection screw is rotated by the rotating motor at its most forward position, the load current is detected by the current detector, and the rotation of the rotating motor based on the load current is detected. The load factor is compared with the overload factor set by the load factor setting device by the load monitoring device, and when it is determined that the load factor of the rotating electric motor exceeds the overload factor setting value, The rotation of the rotating electric motor is stopped via the driving means by the command, the moving motor is operated, the sucking back is performed in a state in which the rotation of the injection screw is stopped, and then the head is moved to the most advanced position. The automatic purging operation in which the injection screw rotates again is performed, and the automatic purging operation is repeatedly performed until the load ratio of the rotating electric motor becomes equal to or less than the overload ratio set value. Resin remaining material is discharged from the removed barrel. Therefore, according to the automatic purging device, the rotating electric motor operates safely and smoothly at an overload ratio set by the load factor setting device or less, and the occurrence of operation failure due to an excessive load is prevented. The operation of automatically and reliably discharging the resin residue from the resin can be performed, and the labor of the operator in the purging operation can be reduced.

According to a seventh aspect of the present invention, the injection screw inserted into the barrel provided with the detachable injection nozzle is rotated by the rotating motor at the most advanced position and is moved to the most advanced position by the moving motor. An automatic purging device of an electric injection molding machine, which performs an automatic purging operation to repeat an operation of moving forward after sucking back in a state of stopping rotation and discharging resin residue in the barrel, A position setting device for setting a movement position of the injection screw; and a retreat movement monitor for determining whether or not the injection screw has started retreating from the most advanced position while the injection screw is rotating at the most advanced position set by the position setting device. Means, and control means for instructing the automatic purge operation when it is determined by the retreat movement monitoring means that the injection screw has started retreating from the most advanced position, Operated by a command from the control means,
It is configured to include the rotating electric motor and driving means for operating the moving electric motor.

In the automatic purging apparatus having this configuration, when the injection screw is rotated by the rotating motor at the most forward position, whether the injection screw is retracted from the most advanced position set by the position setting device during the rotation. The determination is made by the backward movement monitoring means. When it was determined that the injection screw was retracted from the most advanced position, the rotation of the rotating electric motor was stopped via the driving means by a command from the control means, and the moving motor was operated to stop the rotation of the injection screw. After sucking back in the state, the injection screw is moved to the most advanced position, an automatic purge operation in which the injection screw rotates again at the most advanced position is performed, and the automatic purge operation is performed while the injection screw is rotating at the most advanced position. The process is repeated until the resin no longer retreats, whereby the resin residue is discharged from the barrel from which the injection nozzle has been removed. Also in this automatic purging device,
The same operation as the automatic purging device according to the sixth aspect is achieved.

[0016] In the automatic purging apparatus according to claim 6,
While the injection screw is rotating at the most advanced position set by the position setting device for setting the movement position, the injection screw is controlled by the retreat movement monitoring means for determining whether or not the injection screw has started retreating from the most advanced position. When it is determined that has started retreating from the most advanced position, an automatic purge operation is instructed to the driving means, so that the load ratio of the rotation motor of the injection screw and the backward movement of the injection screw from the most advanced position are reduced. In both cases, the state of the load on the rotating motor is monitored, so that an excessive load acting on the rotating motor can be more effectively prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic purging apparatus for an electric injection molding machine according to the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a central processing unit which incorporates a molding operation program and an automatic purging operation program and controls a molding operation by an electric injection molding machine and an automatic purging operation by an automatic purging device A. Unit 3 is connected. Reference numeral 4 denotes an injection servo amplifier (moving motor driving means) connected to the input unit 2 and the output unit 3. The injection screw advance command signal e1 and suckback command signal (reverse command) of the injection screw input from the output unit 3. Based on the signal e2, a drive current i1 is transmitted to an injection servomotor (moving motor) 5 composed of an electric servomotor to operate the injection servomotor 5. Thus, the injection servomotor 5 moves the injection screw of the electric injection molding machine forward or backward in the axial direction via a screw mechanism or the like that converts a rotary motion into a linear motion.

The injection servo amplifier 4 is connected to a position setting device 6 for setting the axial movement position of the injection screw. The position setting device 6 includes a most advanced position setting device 6a for setting the most advanced position of the injection screw, a backward movement confirmation position setting device 6b for setting a position where the injection screw is slightly retracted from the most advanced position, and an injection device. And a suck-back position setting device 6c for setting a suck-back position of the screw. The movement position f of the injection screw, which is detected by an encoder (position detector) 5a attached to the injection servomotor 5, is determined by the position of the injection servo amplifier 4.
Is compared with the set value by the position setting device 6, and the comparison result is input to the input unit 2.

That is, the moving position f of the injection screw is
If the first position comparator 7a determines that the value matches the value set by the most advanced position setting device 6a, a signal f1 indicating that the injection screw has moved to the most advanced position is output to the second position comparator 7b. When it is determined that the value of the injection screw coincides with the value set by the backward movement confirmation position setting device 6b when the injection screw moves away from the most advanced position in the backward direction, a signal f2 for confirming the backward movement due to the unscrew phenomenon of the injection screw is provided. Further, the suck-back position setting device 6c is used by the third position comparator 7c.
Is determined to match the set value by the signal f3 indicating that the injection screw has retreated to the suckback position.
Are respectively input from the injection servo amplifier 4 to the input unit 2. The encoder (position detector) 5a, the backward movement confirmation position setting device 6b, and the second position comparator 7b of the position comparator 7
Thus, the backward movement monitoring means B is configured to confirm that the injection screw is moved away from the most advanced position by the screwing phenomenon due to the resistance to discharge of the resin remaining material in the barrel and the like.

Reference numeral 8 denotes a supply servo amplifier (driving means for a rotating electric motor) connected to the input unit 2 and the output unit 3 based on an injection screw rotation command signal e3 input from the output unit 3. A drive current i2 is sent to a supply servomotor (rotary motor) 9 composed of an electric servomotor to operate the supply servomotor 9. Thereby, the supply servomotor 9
The injection screw is rotated around an axis via a transmission mechanism or the like. The central processing unit 1, the input unit 2, the output unit 3, etc., control means C for operating the injection servo amplifier (moving motor driving means) 4 and the supply servo amplifier (rotating motor driving means) 8. Make up.

The supply servo amplifier 8 is connected to a load factor setting device 10 for setting an overload factor for the supply servomotor 9. The load ratio based on the load current i2x of the supply servomotor 9 detected by the current detector 11 is compared in a current comparator (load monitoring means) 12 provided in the supply servo amplifier 8, and the load current i2x The overload signal f4 is input to the input unit 2 when the motor load factor (load factor) based on the above becomes equal to or higher than the overload factor set value. The above-mentioned motor load factor indicates a ratio of the load current to the rated current of the supply servomotor 9 as a percentage, and an overload factor set value is a predetermined overload factor at which the motor load factor can exceed 100%. Shall be referred to.

Reference numeral 13 denotes a timer for setting the rotation time of the injection screw. The timer starts counting by a timing command signal e4 output from the output unit 3, and closes its a contact 14 to generate a closing signal f5c. Input unit 2
The rotation command signal e of the injection screw.
3 is sent from the output unit 3 to the supply servo amplifier 8, and when the set time has been counted, the a-contact 14 is opened and the open circuit signal f5u is sent to the input unit 2, and the rotation command signal e3 of the injection screw is output. It is to be stopped. Reference numeral 15 denotes a start button connected to the input unit 2. When the start button 15 is pressed, an automatic purge signal f6 is sent to the input unit 2 and the automatic purge device A
Operation is started.

Next, when the resin purging apparatus A of the electric injection molding machine configured as described above discharges the residual resin remaining in the barrel after the molding operation of the thermosetting resin, the automatic purging apparatus A is used. The automatic purging method together with the operation of A will be described with reference to the flowchart of FIG. First,
In order to start the automatic purging operation, an operator removes the injection nozzle from the end of the barrel of the injection unit, or installs a container for receiving the discharged resin below the end of the barrel, and performs a conventional purging operation procedure (1) to ( A preparatory work corresponding to 3) is performed (step S1).

Next, when the automatic purging operation is started by turning on the start button 15 (step S2), the automatic purging device A is operated according to the automatic purging operation program, and is operated according to a command from the central processing unit 1. Since the output unit 3 issues a forward command e1 of the injection screw to the injection servo amplifier 4, the drive current i1 is supplied from the injection servo amplifier 4 to the injection servo motor 5, and the injection servo motor 5 rotates, and the injection screw is rotated. It is moved forward in the axial direction (step S3). Then, the movement position f of the injection screw detected by the encoder 5a of the injection servomotor 5 is the most advanced position setting device 6a of the position setting device 6.
Is reached by the first position comparator 7a of the position comparator 7 (step S).
4).

When the injection screw reaches the most advanced position, the most advanced position signal f1 is sent from the first position comparator 7a via the input unit 2 to the central processing unit 1, so that the central processing unit 1 The timer 13 starts the timekeeping operation in response to the timekeeping command signal e4 output via the output unit 3 (step S5), and at the same time, the a contact 14 of the timer 13 enters and the closing signal f5c is sent from the input unit 2 to the central processing unit. Sent to 1. As a result, the rotation command signal e3 is sent from the output unit 3 to the supply servo amplifier 8, and the supply servo amplifier 8 supplies the drive current i2 to the supply servo motor 9, so that the supply servo motor 9 is driven and the injection screw is driven. Is rotated (step S
6). Due to the rotation of the injection screw, the resin remaining material of the thermosetting resin adhered to the inside of the barrel and the injection screw after the molding operation is gradually discharged from the barrel from which the injection nozzle is removed.

During this time, it is determined whether or not the timer 13 has finished measuring the set time (step S7). If the timer has not finished measuring the set time, the supply servo amplifier 8 is determined.
Drive current i2 supplied to the supply servomotor 9 from
The current is detected as a motor load current i2x by the current detector 11, converted into a motor load factor, and compared with an overload factor set value preset in the load factor setter 10 by the current comparator 12 of the supply servo amplifier 8, It is determined whether the motor load factor of the supply servomotor 9 has exceeded the overload factor set value (step S8).

When the motor load factor of the supply servomotor 9 does not exceed the overload factor set value, the injection screw moving position f input from the encoder 5a of the injection servomotor 5 to the injection servo amplifier 4 The second position comparator 7b of the position comparator 7 is monitored by the backward movement monitoring means B to determine whether or not the vehicle has retreated to the backward movement confirmation position f2 set in the backward movement confirmation position setting device 6b of the position setting device 6. (Step S9). Due to the resistance of the thermosetting resin remaining in the barrel to discharge of residual resin, etc., the injection screw causes a so-called screw-off phenomenon, and the retracted movement confirmation position f
2 and when it is determined in step S8 that the motor load factor of the supply servomotor 9 has exceeded the overload factor set value, the central processing unit 1 sends the output screw 3 Since the rotation stop command e3s is issued to the supply servo amplifier 8, the supply servo motor 9
Rotation of the injection screw is stopped (step S1).
0) Also, the suck back command signal e2 of the injection screw
Is output to the injection servo amplifier 4, so that the injection servomotor 5 is rotated in the reverse direction and the injection screw moves backward to perform a suck-back operation (suck-back) (step S1).
1).

This suckback operation is performed by the encoder 5a.
Is determined by the third position comparator 7c of the position comparator 7 and continued until the retracted position of the injection screw detected by the above reaches the suckback position f3 set in the suckback position setting device 6c of the position setting device 6. (Step S12). When the injection screw reaches the suck-back position f3, an injection screw forward command e1 is issued from the input unit 2 to the injection servo amplifier 4 via the central processing unit 1 and the output unit 3, so that the injection servo motor 5 is rotated forward. The injection screw is advanced (step S13), and the position detector 5a
When it is confirmed that the movement position of the injection screw detected at step S11 has reached the most advanced position f1 set in the most advanced position setting device 6a of the position setting device 6 (step S14), the central processing unit 1 determines The timer 1 via the output unit 3
3, a timer reset command e4r is issued (step S4).
15) Therefore, returning to the step S5, the timer 1
No. 3 interrupts the clocking of the rotation time of the injection screw, which has been continued up to that time, and newly starts the clocking of the set time.

In the automatic purging operation from step S5 to step S15, the motor load ratio of the supply servomotor 9 is reduced to an overload ratio set value or less according to an automatic purging operation program built in the central processing unit 1. Until the injection screw is rotated at its most advanced position, it is repeatedly performed until the injection screw does not retreat from the most advanced position due to a screw removal phenomenon due to resistance to discharge of resin residue. In steps 8 and 9, the motor load factor of the supply servomotor 9 does not reach the overload factor set value, and the injection screw is rotating at its most forward position.
If the screwing phenomenon of retreating from the foremost position does not occur due to resistance to discharge of resin residue, etc., steps 6 and 7
, The injection screw rotates for the time set by the timer 13 to continue the operation of discharging the resin remaining material in the barrel. The rotation time of the injection screw based on the set time of the timer 13 is a time required until no powdery resin remains after the semi-molten or solidified thermosetting resin discharged from the barrel. Is set in advance by a trial and error test.

When the rotation time of the injection screw at the most advanced position exceeds the set time in step S7, the timer 13
A contact 14 is opened and the open circuit signal f5u is
Is sent to the central processing unit 1 via the output unit 3 so that the rotation stop command e3s of the injection screw is issued to the supply servo amplifier 8 through the output unit 3, and the supply servomotor 9 is stopped. Then, the rotation of the injection screw is stopped (step S16), and the purging operation is completed by the operator performing a post-setup operation similar to the procedure (6) in the conventional purging operation (step S17).

In the above automatic purging apparatus and the automatic purging method, the supply servomotor for rotating the injection screw when the injection screw is rotated at its most advanced position to discharge the resin remaining material in the injection screw and the barrel. 9 is detected, a motor load factor based on the detected load current i2 is compared with an overload factor set in advance by the load factor setting device 10, and it is determined whether the motor load factor exceeds the overload factor. When the overload ratio is exceeded, and when the injection screw is unscrewed based on the resistance to discharge of the residual resin, the backward movement of the position setting device 6 from the most advanced position is set in the position setting device 6b. It is determined whether or not the vehicle has retreated to the confirmation position f2, and if it is confirmed that the vehicle has retracted, the injection screw is sucked back to the suckback position. Forward movement to the most forward position, the automatic purging operation of the rotation at the most forward position until the motor load ratio becomes equal to or less than the set value of the overload ratio, and the injection screw is moved to the most forward position by a screw-off phenomenon. It is repeated until it cannot be retreated.

Therefore, during the purging operation, there is no possibility that an excessive load acts on the supply servomotor 9 for rotating the injection screw to cause an operation failure, and the resin adhering and remaining in the barrel or the injection screw is prevented. The remaining material can be automatically and smoothly discharged reliably, and the labor required by the operator can be reduced as much as possible to reduce the labor.

In the above embodiment, it is determined whether or not the motor load factor based on the load current of the supply servomotor 9 has exceeded the overload factor set in the load factor setting device 10, and the injection screw is used. The backward movement confirmation position f2 set in the position setting device 6 from the most advanced position due to the unscrewing phenomenon.
It is determined whether or not the injection screw has retreated, and based on the results of these determinations, the injection screw is rotated at the most advanced position, sucked back, and an automatic purge operation of moving from the sucked back position to the most advanced position is performed. Therefore, it is preferable to be able to extremely reliably prevent an excessive load from acting on the supply servomotor 9. However, the automatic purge operation is not necessarily performed by the motor load ratio and the retraction due to the unscrewing phenomenon of the injection screw. It is not necessary to make a determination based on both the movement and the movement, and the determination may be made based on either one of the determination results. Even in this case, it is possible to prevent an excessive load from acting on the supply servomotor 9. it can.

In the above embodiment, when the motor load factor of the supply servomotor 9 exceeds the overload factor set value, or when the injection screw starts retreating due to a screwing phenomenon, Since the suckback is performed after the rotation of the injection screw is stopped, it is possible to effectively prevent an excessive load from acting on the supply servomotor 9, which is preferable. However, the suckback is performed without stopping the rotation of the injection screw. You may. Even in this case, the action of an excessive load on the supply servomotor 9 can be suppressed.

[0035]

As described above, according to the first aspect of the present invention, the injection screw inserted into the barrel from which the injection nozzle has been removed is rotated at its most advanced position by the rotating electric motor. When the load ratio of the motor for use exceeds the preset overload ratio set value, the injection screw is sucked back by the preset stroke by the moving motor and then moved to the most advanced position, and thereafter, at the most advanced position. The rotation of the injection screw, suckback, the automatic purging operation of the movement to the most advanced position is repeatedly performed until the load factor of the rotating electric motor becomes equal to or less than the overload factor set value, and the resin remaining material in the barrel is removed. During discharge of residual resin from inside the barrel, an excessive load acts on the motor for rotating the injection screw, which prevents malfunctions. Smooth, it is possible to reliably perform the discharge operation.

According to the second aspect of the present invention, during the operation of discharging the resin residue from the inside of the barrel, the motor for rotating the injection screw is determined depending on whether or not the injection screw has been moved backward from the most advanced position during rotation. The operation state of the overload with respect to is monitored, so that it is possible to prevent an excessive load on the rotating electric motor from causing an operation failure, and to prevent the residual resin material as in the first aspect of the present invention. Discharge work can be performed smoothly and reliably.

According to the third and fourth aspects of the present invention, when the load factor of the rotary motor increases, the rotation of the injection screw is stopped and the automatic purging operation is performed. Since the load factor can be reduced quickly, the rotating electric motor is not forced, and the operation of discharging the resin residue from the barrel can be performed more smoothly, reliably and safely.

According to the fifth aspect of the present invention, when the resin remaining material is a thermosetting resin, it is fixed in the injection screw or the barrel at the end of molding or when molding is interrupted for a certain time during molding. Residual material of the thermosetting resin which can be easily removed can be easily discharged from the inside of the barrel.

According to the present invention, the load factor based on the load current of the rotating motor detected by the current detector exceeds the overload factor set by the load factor setting device. When determined by the load monitoring means, or when the injection screw is rotating at the most forward position, and when the backward movement monitoring means determines that the injection screw has retracted from the most advanced position set by the position setting device, a command from the control means is issued. As a result, the drive means operates, and the rotation motor and the movement motor are operated to perform the automatic purging operation. Therefore, the rotation motor can be safely and smoothly operated at an overload rate equal to or less than the overload rate set by the load factor setting device. To prevent operation failure due to an excessive load, thereby automatically and reliably discharging the residual resin from the barrel. It is possible to reduce the labor of workers in.

According to the eighth aspect of the present invention, the load on the rotary motor is determined based on both the load factor of the rotary motor of the injection screw and the presence or absence of the backward movement from the most advanced position during the rotation of the injection screw. Is monitored, it is possible to more effectively prevent an excessive load from acting on the rotating electric motor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic purge device of an electric injection molding machine according to the present invention.

FIG. 2 is a flowchart showing the operation of the automatic purge device of the electric injection molding machine of the present invention.

[Description of Signs] 1 Central Processing Unit 4 Injection Servo Amplifier (Driving Means of Moving Motor) 5 Injection Servo Motor (Moving Motor) 5a Encoder (Position Detector) 6 Position Setter 6b Reverse Movement Confirmation Position Setter 7 Position comparator 8 Supply servo amplifier (driving means for rotating motor) 9 Supply servo motor (rotating motor) 10 Load factor setting device 11 Current detector 12 Current comparator (load monitoring device) A Automatic purge device B Reverse movement monitoring Means C Control means

Claims (8)

[Claims] An injection screw inserted into a barrel from which an injection nozzle has been removed is rotated by a rotary motor at its most advanced position, and the load factor of the rotary motor is set to a preset overload factor set value. When it exceeds, the injection screw is sucked back by the preset stroke by the moving motor and then moved to the most advanced position, and thereafter, the rotation of the injection screw at the most advanced position, suckback, and movement to the most advanced position are performed. Automatic purging of the electric injection molding machine, wherein the automatic purging operation is repeatedly performed until the load ratio of the rotating electric motor becomes equal to or less than the overload ratio set value, and the resin remaining material in the barrel is discharged. Method. 2. An injection screw inserted into a barrel from which an injection nozzle has been removed is rotated by a rotating motor at its most advanced position, and whether or not there is a retreat from the most advanced position during rotation of the injection screw. When the injection screw starts retreating, the injection screw is sucked back by a predetermined stroke by a moving motor and then moved to the most forward position, and thereafter, the rotation of the injection screw at the most advanced position, The electric purging operation of the back and the movement to the most advanced position is repeatedly performed until the retreating movement during rotation of the injection screw at the most advanced position is stopped, and the resin remaining material in the barrel is discharged. Automatic purging method for injection molding machines. 3. When the load ratio of the rotary electric motor exceeds the overload ratio set value during rotation of the injection screw at the most advanced position, the rotation of the injection screw is stopped to perform the automatic purging operation. The method for automatically purging an electric injection molding machine according to claim 1, wherein: 4. When the injection screw starts rotating backward from the most advanced position during rotation of the injection screw at the most advanced position, the rotation of the injection screw is stopped to perform the automatic purging operation. Item 3. An automatic purging method for an electric injection molding machine according to Item 2. 5. The automatic purging method for an electric injection molding machine according to claim 1, wherein the resin residual material is a thermosetting resin. 6. An injection screw inserted into a barrel provided with a detachable injection nozzle has stopped rotating by the rotating motor at its most advanced position and from said most advanced position by the moving motor. In the automatic purging device of the electric injection molding machine, which performs an automatic purging operation that repeats an operation of moving forward after sucking back in the state, and discharging resin residual material in the barrel, A current detector for detecting a load current;
Load monitoring means for determining whether or not the load factor of the rotating motor based on the load current detected by the current detector exceeds an overload factor set by a load factor setting device; and When it is determined that the rate exceeds the overload rate, control means for instructing the automatic purge operation, and drive means for operating according to a command from the control means to operate the rotating motor and the moving motor, An automatic purging device for an electric injection molding machine, comprising: 7. An injection screw inserted into a barrel provided with a removable injection nozzle stops rotating from its most advanced position by a rotating motor at its most advanced position and from its most advanced position by a moving motor. In the automatic purging device of the electric injection molding machine, which performs an automatic purging operation that repeats an operation of forwardly moving after sucking back in a state and discharging resin residue in the barrel, the movement of the injection screw A position setting device for setting the position,
While the injection screw is rotating at the most forward position set by the position setting device, the backward movement monitoring means for determining whether or not the backward movement has been started from the most forward position, and the injection screw is finally rotated by the backward movement monitoring means. Control means for instructing the automatic purging operation when it is determined that retreat has been started from the forward position, and driving means for operating in response to a command from the control means and operating the rotating motor and the moving motor. An automatic purge device for an electric injection molding machine. 8. The retreating means for judging whether or not the injection screw has started retreating from the most advanced position while the injection screw is rotating at the most advanced position set by a position setting device for setting the moving position thereof. 7. The electric motor according to claim 6, wherein the automatic purge operation is instructed to a driving unit when it is determined by the movement monitoring unit that the injection screw has started retreating from the most advanced position. Automatic purging device for injection molding machines.