JP5563229B2 - Control device for injection molding machine and control method therefor - Google Patents

Description

  The present invention relates to a control device for an injection molding machine that injects a material into a mold and a control method therefor.

  An injection molding machine inputs raw materials from a hopper, heats, melts and kneads the materials with a heating cylinder, and injects the plasticized material into a mold-clamped cavity from a nozzle to form a molded product. . When injecting from the nozzle, the plasticizing material is pushed into the cavity of the mold at high pressure by a screw or a plunger. An injection motor is mechanically connected to the screw and the plunger, and an injection operation is performed by converting the rotational driving force of the motor into a reciprocating motion of the screw and the plunger.

  By the way, when a resin clogging or the like in the nozzle or the mold communicated with the heating cylinder occurs, the resin pressure in the heating cylinder rapidly increases and the screw or the like is overloaded. In Patent Document 1, this overload state is caused by interposing a drive transmission canceling mechanism between the drive transmission path from the injection servo motor to the screw, so that a screw of a predetermined value or more is applied to the drive transmission path. A technique for instantaneously stopping the forward movement of the vehicle is disclosed.

  In Patent Document 2, torque limit values are set for the forward / backward servomotor and the rotation servomotor that drive the screw, and the screw is moved forward / backward and rotated sequentially by a predetermined amount. At this time, when the monitoring time elapses before the movement or rotation operation is completed or the positional deviation exceeds the monitoring value, it is detected that the resin viscosity is high and the screw is overloaded. As described above, a technique for preventing damage due to overloading of a screw or the like due to a solidified state or a semi-molten state of a resin in the screw when the molding is once restarted after the molding is disclosed.

JP-A-11-115006 JP 2001-79904 A

  However, the techniques disclosed in Patent Documents 1 and 2 require that an operator perform a recovery operation when an injection abnormality is detected and the injection operation is stopped. For this reason, the operation of the injection molding machine is stopped until the worker takes action after detecting the injection abnormality.

  Accordingly, an object of the present invention is to suppress a decrease in productivity due to an injection abnormality of an injection molding machine.

To solve the above problems, a control apparatus according to the present invention includes: a melting unit for melting the material at heating, and injection means for injecting the material melted by the melting unit into the mold cavity, with the injection means a control device for an injection molding machine provided with a detection means for detecting an injection abnormality, and when detecting the injection abnormality by said detecting means, and a temporary stop of the injection process before SL materials, Heating the material for a predetermined time and restarting the injection process of the material are performed continuously .

  According to the present invention, it is possible to suppress a decrease in productivity due to an injection abnormality of an injection molding machine.

1 is an external perspective view of an injection molding machine 1 according to an embodiment of the present invention. 1 is a cross-sectional view of an injection molding machine 1. FIG. It is an expanded sectional view of the D section shown in FIG. It is a figure which shows the operation | movement procedure of the injection mechanism 9 which concerns on Example 1. FIG. It is a figure which shows the operation | movement procedure of the injection mechanism 9 which concerns on Example 2. FIG. 2 is a block diagram showing a functional configuration of the injection molding machine 1. FIG.

  Embodiments of the present invention will be described below in detail with reference to the drawings. The embodiment described below is an example as means for realizing the present invention, and the present invention can be applied to a modified or modified embodiment described below without departing from the spirit of the present invention.

  FIG. 1 is an external perspective view of an injection molding machine 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the injection molding machine 1. FIG. 3 is an enlarged cross-sectional view of a portion D shown in FIG. An injection molding machine 1 according to the present invention detects a melting mechanism 20 for melting a material, an injection mechanism 9 for injecting a material melted by the melting mechanism 20 into a cavity of a mold 3, and an injection abnormality in the injection mechanism 9. Detecting unit S1 (see FIG. 6). Other configurations are the same as those of a general injection molding machine, and include, for example, a mold clamping mechanism 5 and a material supply unit 6.

  The melting mechanism 20 includes a barrel 22, a rotor 23 superimposed on the barrel 22, a heater that heats the barrel 22 and the rotor 23, and a rotor drive motor 21 that rotationally drives the rotor 23.

  The rotor 23 is rotatably accommodated in the casing 27 and has a sliding contact surface 23 a that is in sliding contact with one end surface of the barrel 22. The rotor 23 includes a spiral groove formed in the sliding contact surface 23a and extending in the radial direction of the rotation axis of the rotor 23, and a plasticizing path 25 formed in the sliding contact surface 23a and serving as a resin flow path. Have. The spiral groove is supplied with resin from the outer end, and the inner end communicates with the open end of the material flow path 10 of the barrel 22.

  In the barrel 22, the material flow path 10 is opened at the center thereof, and a heater is disposed therein. By controlling energization to the heater, the resin interposed in the material flow path 10 and the plasticizing path 25 is heated and softened and melted.

  A rotor drive motor 21 is connected to the rotor 23 via the drive transmission mechanism 8, and the operation of the rotor drive motor 21 keeps the end surface of the rotor 23 having a spiral groove and the one end surface of the barrel 22 in close contact with each other. The material is rotated about the material flow path 10.

  Under such a configuration, the pellet-shaped resin is stored in a hopper of the material supply unit 6 attached to the casing 27, and is supplied from here to the outer end portion of the spiral groove of the rotor 23 through the casing 27. Then, as the rotor 23 is rotated by the operation of the rotor drive motor 21, it moves in the plasticizing path 25 from the outer end portion of the spiral groove. At the same time, the softening and melting of the resin proceeds by receiving heat from the heater and the viscosity resistance of the resin with respect to one end surface of the barrel 22 increases. As a result, the resin is plasticized and kneaded with an increase in pressure. Flow to the department. The molten resin that has reached the inner end of the spiral groove flows into the material flow path 10 on the barrel 22 side from here.

  The injection mechanism 9 connects the melting mechanism 20 and the cavity, communicates with the material flow path 10 through which the molten material passes, and stores a part of the material that passes through the material flow path 10. A chamber 12 (reservoir chamber), an injection plunger 15 (extrusion member) that is slidable in the chamber 12 (reservoir chamber) and pushes the material drawn into the chamber 12 toward the cavity, and an injection plunger And an injection motor 16 (driving means) for driving 15 and a heater H1 (heating means) for heating the material flow path 10. The injection mechanism 9 includes a nozzle 14 that communicates with the end of the material flow path 10 on the gate 11 side, and a transmission unit 7 that transmits the driving force of the injection motor 16 to the injection plunger 15.

  The resin flowing in from the melting mechanism 20 is stored in the chamber 12 through a check valve 24 for preventing the resin from flowing back to the plasticizing path 25 side. The chamber 12 communicates with the material flow path 10 and extends to the side of the material flow path 10 and is provided in the barrel 22.

  The heater H1 is installed in the fixed mold 3a in which the nozzle 14 is disposed. That is, the injection mechanism 9 is driven by a pre-plunger method.

  The injection plunger 15 is slidably fitted to the chamber 12, and the operation of the injection motor 16 connected via the transmission unit 7 causes the resin interposed in the chamber 12 to flow through the material flow path 10. The pressure is fed by a predetermined amount to the nozzle 14 side. Here, the rotational driving force generated by the operation of the injection motor 16 is converted into a straight drive by a ball screw connected to the transmission unit 7 to drive the injection plunger 15.

  A drive gear 31 is attached to the injection motor 16, and the drive gear 31 can be rotated forward and backward by a predetermined amount by the operation of the injection motor 16. The driving force is transmitted in the order of the intermediate gear 32, the second intermediate gear 33, and the driven gear 35 that mesh with each other, and the ball nut 36 that is integrally connected via the driven gear 35 and the bolt 34 is rotationally driven. Since the ball screw shaft 37 screwed into the ball nut 36 is prevented from being rotated by the rotation preventing means, the rotation operation is converted into a straight movement operation, and the injection plunger 15 connected to the ball screw shaft 37 is replaced with the chamber 12. Can be slid along. In the present embodiment, a gear is used as the transmission portion 7 from the injection motor 16 to the ball nut 36, but any power transmission mechanism such as a toothed belt can be employed.

  The nozzle 14 whose front end faces the cavity is connected to the end of the material flow path 10, and a predetermined amount of resin pumped from the chamber 12 by the advance of the injection plunger 15 (movement toward the nozzle 14) is fed to the gate 11. Into the cavity.

  FIG. 6 is a block diagram showing a functional configuration of the injection molding machine. 100 is a control device for driving and controlling the injection molding machine, 105 is a CPU for arithmetic processing, 102 is a ROM for storing the control program and calculation data of the injection molding machine, and 103 is used for temporary storage of the control program and calculation data RAM. 101 is an EEPROM (Electrically Erasable and Programmable Read Only Memory) for storing each molding condition and the number of moldings, 107 is a servo amplifier that drives a servo motor for injection and mold clamping, and 104 is an FPGA that controls the servo amplifier 107. (Field Programmable Gate Array) 106 is a motor driver that drives a servo motor. Reference numeral 108 denotes an LCD (Liquid Crystal Display) having a display device function for interfacing with an operator and a touch panel function as an operation means, and 109 denotes a switch as an auxiliary operation means.

  The CPU 105 reads a program stored in the ROM 102 and controls the injection molding machine while using the RAM 103 as a work area. Further, the temperature is obtained from the temperature sensor 112 and the temperature sensor 113, and the heater 110 of the barrel 22 and the heater 111 of the fixed mold 3a for raising the temperature of the nozzle 14 are controlled to turn the heaters 110 and 111 on and off. . When the injection and mold clamping motors are controlled, a command is issued to the servo amplifier 107 through the FPGA 104. An encoder is attached to the motor. When the mold clamping mechanism 5 is driven, the mold clamping motor 18 is rotated forward and backward to drive the ball screw shaft 19, and the movable mold 3b is moved in the direction facing the fixed mold 3a.

  Here, as a start-up operation of the injection molding machine 1, a purge operation is performed in which the resin remaining in the material flow path 10 in the molding operation completed last time is replaced with a new resin. In the purge operation, the temperature of the heater is raised, and the injection plunger 15 is driven in order to draw out the residual resin from the chamber 12 and the material flow path 10. At this time, in the injection operation in the normal purge operation, the injection plunger 15 can move from the position C in FIG.

  However, if there is an injection abnormality, that is, if the residual resin is not sufficiently remelted and the resin is stuck in the passage, or if the resin is clogged due to heat escape around the gate 11, the injection plunger 15 Will not be able to push out the resin and will stop halfway. However, since the injection motor 16 continues to apply torque to the injection plunger 15, the injection plunger 15 is overloaded.

  The abnormal injection due to the injection plunger 15 breaks the connection portion between the members, such as the connection portion between the injection plunger 15, the drive system of the injection plunger 15, or the fixed side mold 3a where the nozzle 14 is disposed and the casing 27. Problems may occur. Moreover, the abnormal injection due to the injection plunger 15 is often a malfunction caused by a shortage of heat in the material flow path 10 or the like, and can often be resolved by applying heat. However, merely detecting an abnormal injection and giving a warning to the worker takes time until the worker notices the warning and takes action, which is a major factor in reducing productivity.

  Therefore, in this embodiment, an injection abnormality during the purge operation is detected, and if there is an abnormality, the injection operation is temporarily stopped to suppress the occurrence of an overload state. Then, after the injection operation is stopped, the injection operation is continuously resumed by performing a certain process.

[Operation procedure of injection plunger 15]
FIG. 4 is a diagram illustrating an operation procedure of the injection mechanism 9 according to the first embodiment. At the start of the purge operation, the operator sets the temperature of the heaters (110, 111) and the drive setting of the injection plunger 15. The movement of the injection plunger 15 is started after the heater is heated up to the set temperature. Note that the heater temperature at the start-up of the injection molding machine 1 is controlled so as to be raised by a predetermined temperature with respect to the temperature set for normal molding, so that the heater temperature during the purge operation is To do. This makes it possible to start up smoothly, but the temperature of the heater during the purge operation may be set separately from the temperature setting for normal molding.

  First, the injection plunger 15 is driven in step S11, and the injection plunger 15 is moved to a predetermined position (position B shown in FIG. 3) within a predetermined time after driving the injection motor 16 in step S12. It is determined whether or not. The injection plunger 15 is controlled by a speed command and a torque command given to the injection motor 16. Further, the movement position of the injection plunger 15 is calculated based on the speed command and the elapsed time after the command. When the injection plunger 15 has reached the determination position B arbitrarily set at a predetermined time, it is assumed that the residual resin has been discharged normally, and the residual resin in the material flow path 10 is continuously replaced with a new one. A process for continuing the purge operation is performed until the resin is replaced, or when the purge operation is completed, a normal molding operation can be performed. If the injection plunger 15 does not reach the position B within the time determined in advance in step S12, there is a high possibility of an abnormal injection, so the process proceeds to step S13, the energization of the injection motor 16 is stopped, and the injection plunger The driving of 15 is temporarily stopped. That is, the injection process of the molten material is temporarily stopped.

  Next, the process proceeds to step S14, and as a process after stopping the driving of the injection plunger 15 during the purge operation, the driving of the injection plunger 15 is stopped and the output to the heater is maintained as it is, and the process waits for a predetermined time. . This stop time can be determined in advance by setting by an operator during start-up work. Thus, by automatically creating an environment in which the resin is easily melted, resin clogging due to insufficient remelting of the residual resin or heat escape around the gate 11 can be eliminated. After a predetermined time has elapsed since the injection process was stopped in step S14, the process returns to step S11, the injection motor 16 is operated to restart the plunger drive (injection process), and the determination in step S12 is performed again. Do. At this time, the material flow path 10 may be heated until the predetermined time elapses after the injection process is stopped, and an environment in which the resin is easily melted may be obtained.

  In step S12, when the injection plunger 15 does not reach the position B again within a predetermined time, the process proceeds to step S13 and the above-described operation is repeated. The number of times to repeat the processes after step S13 can be set in advance by the operator. In this case, the number of repetitions is counted when moving from step S12 to step S13. If it is determined in step S12 that the injection plunger 15 has reached the set position within the predetermined number of times, the injection has been performed normally.

  When the injection plunger 15 does not reach the determination position B again within a predetermined time in step S12 ((set number of repetitions + 1) times) after the processing of steps S12 to S14 has reached the set number of repetitions. In this case, it is necessary to perform a separate treatment by an operator, or it is highly likely that the abnormality in the plunger drive is not due to a lack of heat in the resin passage. Therefore, a warning may be activated after the processing in step S13. Good. However, the number of times is not necessarily limited.

  The purge operation is performed in order to replace the resin remaining in the material flow path 10 with a new resin, as long as it can be injected with a force that does not cause the material flow path 10 to be damaged. On the other hand, in a normal molding process, it is required that the injection torque can be set according to the characteristics of the resin used and the shape of the molded product. For this reason, in this embodiment, the injection torque set in the purge operation and the molding process can be set to different values. Thereby, it is possible to improve the life of the drive unit without unnecessarily applying a load to the injection motor 16.

  In the first embodiment, the injection abnormality at the time of the purge operation is detected. However, the present embodiment is different in that the injection abnormality at the time of the metering process for the first molding operation after the purge operation is completed is detected.

  Since the purge operation is performed with the mold open, the gate 11 may be clogged with resin due to heat escape during the purge operation or at the end of the purge operation. For this reason, in this embodiment, the metering process is controlled with a constant torque, and an injection abnormality is detected when a predetermined torque is exceeded.

  FIG. 5 is a diagram illustrating an operation procedure of the injection mechanism 9 according to the second embodiment. First, in step S21, when the operator needs to change the driving of the injection plunger 15 and the temperature settings of the heaters 110 and 111, they are set and the weighing process is started.

  In step S22, a weighing process for molding is performed. The weighing process refers to moving the injection plunger 15 to a predetermined weighing position B. Here, in the purge operation, in order to drive the injection mechanism 9 and replace the resin in the material flow path 10 with the new resin as few times as possible, the injection plunger 15 is largely retracted to the position C to cause the new resin to flow into the chamber 12. Many are housed inside. For this reason, when the purge operation is normally performed, the stop position of the injection plunger 15 is between A and AB at the end of the purge operation, and the metering process in step S22 performs the backward operation to the position B. It becomes.

  In step S23, it is detected whether or not the injection motor 16 has been driven with a predetermined torque. If it is within the predetermined range, the process proceeds to step S24, and when the molten resin delivered from the rotor 23 is accommodated in the chamber 12 and the weighing is completed, the injection plunger 15 is driven forward in step S25 to inject the molten resin. Done. If step S22 is a backward movement, in step S23, the torque is normally within a predetermined range, and the weighing process can be completed.

  On the other hand, if the injection plunger 15 is not normally driven due to gate clogging or the like during the purge operation in step S22 and the stop position of the injection plunger 15 is between BC at the end of the purge operation, the process proceeds to step S22. The weighing process is a forward movement to position B. At this time, since the injection plunger 15 cannot move forward to the position B and becomes overloaded, it is detected in step S23 that the injection motor has not been driven with a torque within a predetermined range. In this case, since there is a high possibility of an injection abnormality, the process proceeds to step S26, the energization to the injection motor 16 is turned off, and the weighing process is temporarily stopped.

  Next, the process proceeds to step S27, and the heaters 110 and 111 are heated during the plunger drive stop time as a process after the drive of the injection plunger 15 is stopped during the metering process. In this embodiment, since the heater is actively heated, the stop time during the molding operation can be shortened. As in the first embodiment, the injection operation may be performed after elapse of a predetermined time without increasing the temperature of the heater.

  After a predetermined time has elapsed in step S28, the process proceeds to step S29, and an injection operation is performed to confirm whether or not the injection plunger 15 can be normally driven. That is, the injection plunger 15 is advanced with the position A as a target. In step S30, it is determined whether the plunger has reached position A within a predetermined time. If it is determined that the plunger has not reached, the process returns to step S26 and the subsequent processing is repeated. On the other hand, if it is determined that it has arrived, the process returns to step S22 again to perform the weighing process. Since the metering process here is a movement to the position B, the injection plunger 15 moves backward to the position B by the above flow. Thereafter, the weighing process can be completed by the same process as described above.

  As described above, according to the present embodiment, when there is an abnormality in the driving of the injection plunger 15, the injection plunger 15 or the drive transmission mechanism of the injection plunger 15 is detected by detecting the abnormality and stopping the injection plunger 15. 8 can be prevented from being damaged. Further, since the operation can be continued by recovering the environment where the driving of the injection plunger 15 can be resumed, the usability can be improved and the operation can be completed more safely.

  The situation in which the injection plunger 15 is abnormally injected is not limited to the purge operation or the metering operation, but is a gate during the injection operation in the normal continuous molding operation or when the injection molding machine is held in the mold open state. It is a wide variety such as when 11 is cold. Therefore, the present invention is effective in eliminating all of the abnormal operation of the injection mechanism 9 due to the lack of heat.

  In the above-described embodiment, the example in which the injection plunger 15 is temporarily stopped and waiting for a predetermined time or the heater is heated to a predetermined temperature has been described, but provided separately from the heater described above. The energization of the heater may be turned on. Further, the determination position for determining the arrival position of the injection plunger 15 may not be one. The injection plunger 15 may be stopped using a known configuration such as providing a drive release mechanism for the injection plunger 15.

  Further, the basic configuration of the injection molding machine in the above-described embodiment is substantially the same as a known one. Therefore, for example, the melting mechanism 20 is not limited to the rotor / barrel type as described above, and the present invention can be applied to a type having a heating cylinder and in which an injection plunger is slidably fitted to the heating cylinder. In addition, not only the melting mechanism 20 but various basic configurations of the injection molding machine can be used. Further, the drive member of the injection mechanism 9 is not limited to the plunger, and the present invention can also be applied to a screw type. That is, the present invention is not limited to the above-described embodiments, and can be arbitrarily changed according to the use and purpose thereof.

5 Clamping mechanism 6 Material supply unit 9 Injection mechanism 10 Material flow path 11 Gate 12 Chamber 14 Nozzle 15 Injection plunger 16 Injection motor 20 Melting mechanism 100 Control device S1 Detection unit

Claims (6)

A melting means for melting the material by heating ;
An injection means for injecting the material melted in the mold cavity with the molten section,
Detecting means for detecting an injection abnormality in the injection means;
An injection molding machine control device comprising:
When detecting the injection abnormality by said detecting means, a continuous and temporary suspension of the injection process before SL materials, heating and the material of the predetermined time, and a restart of the injection process of the material The control device characterized by performing to. The injection means is
A material flow path connecting between the melting means and the cavity and through which the molten material passes;
Heating means for heating the material flow path,
2. The control device according to claim 1, wherein the heating unit heats the material flow path until the predetermined time elapses after the injection process is stopped. The injection means is
An extrusion member for extruding the material melted by the melting means to the cavity side;
Driving means for driving the pushing member,
The detection unit is configured such that when the pushing member does not move to a predetermined position within a predetermined time after driving the driving unit, or when the driving unit is not driven with a torque within a predetermined range, The control apparatus according to claim 1, wherein an injection abnormality is detected. The injection means is
A material flow path connecting between the melting means and the cavity and through which the molten material passes;
A storage chamber that communicates with the material flow path and stores a portion of the material that passes through the material flow path;
The control device according to claim 3, wherein the pushing member is slidable in the storage chamber and pushes the material drawn into the storage chamber toward the cavity.   The control device according to claim 1, wherein the detection unit detects the injection abnormality during a purge operation. A melting means for melting the material by heating ;
An injection means for injecting the material melted in the mold cavity with the molten section,
Detecting means for detecting an injection abnormality in the injection means;
An injection molding machine control method comprising:
When detecting the injection abnormality by said detecting means, a continuous and temporary suspension of the injection process before SL materials, heating and the material of the predetermined time, and a restart of the injection process of the material The control method characterized by performing to.

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