JPH0710554B2 - Molding start-up control method and apparatus for injection molding machine - Google Patents

Description

Description: (a) Field of Industrial Application The present invention relates to a molding start-up control method and apparatus for an injection molding machine.

(B) Conventional technology When molding is performed using an injection molding machine, a good molded product can be obtained by molding under the already-obtained steady molding conditions. However, at the time of starting the molding after exchanging the mold or restarting the molding after interruption of the molding, it is possible to perform good molding under steady molding conditions due to the gate clogging at the start of molding, the mold temperature decrease, etc. Can not. For this reason,
Japanese Unexamined Patent Publication No. 63-109035 discloses a technique in which a predetermined number of shots are formed at a filling pressure for preforming at the time of start-up of the molding, and after the completion of the predetermined number of shots, a steady forming condition is automatically switched. There is. If the filling pressure at the time of molding startup does not reach the specified value, the injection / filling and holding steps are performed at the filling speed and holding pressure of the steady molding conditions, and the filling pressure reaches the specified value. As described above, the injection / filling and pressure-holding steps are performed with the preforming filling pressure.

(C) Problems to be Solved by the Invention However, in the conventional molding start-up control method for an injection molding machine as described above, a semi-finished product is molded from the first shot to several shots at the time of molding start-up. There is a problem that is done. That is, in the case of molding with a hot runner mold having a manifold, the resin inside the manifold of the mold is heated and temperature-controlled during the molding interruption or before the molding is started. Part of the mold flows back to the sprue bush side of the mold and flows out of the mold, and molding is performed in a state where the mold cavity is not completely filled (so-called short shot), and a semi-finished product is molded. Depending on the shape of the semi-finished product, defective ejection of the molded product due to the eject pin or defective suction of the vacuum suction type automatic take-out machine may occur, making automatic take-out impossible. In such a case, after all, it is necessary to manually take out the semi-finished product, and automatic start-up of molding cannot be realized. Furthermore, since it takes time to manually remove the semi-finished product, the residual resin in the manifold flows out of the mold during that time, and the molding of the semi-finished product is further repeated. The present invention aims to solve the above problems.

(D) Means for Solving the Problems The present invention solves the above problems by performing preforming in which a large amount of molten resin is filled at a low filling pressure.
That is, the method of the present invention is a molding start-up control method of automatically switching to steady molding under steady molding conditions after performing preforming under preset molding conditions for a set number of shots. The gist is that the preforming filling pressure smaller than the filling pressure of the molding condition and the preforming measurement value larger than the measurement value of the steady molding condition are set.

Further, the molding start-up control device of the injection molding machine for carrying out the above method includes a servo valve (44) for controlling the hydraulic pressure and the amount of hydraulic oil supplied to the injection cylinder (16) and a pressure detection for detecting the filling pressure. Device (20, 22), speed detector (28, 30) for detecting the filling speed, position detector (28, 62) for detecting the position of the screw (12), pressure detector and speed detector Servo control device (24) that feedback-controls the operation of the servo valve according to the command from the setter by the signal of
And a metering value controller (64) that controls the rotation of the screw by the signal from the position detector to control the measured value of the molten resin according to the command from the setter, and a steady state that sets the filling speed during steady molding. A molding filling speed setting device (50), a steady molding filling pressure setting device (52) that sets the filling pressure during steady molding, and a steady molding weighing value setter (70) that sets the weighing value during steady molding, Preforming filling pressure setting device (54) that sets the filling pressure during preforming that is smaller than the filling pressure during steady molding, and preforming weighing that sets the measured value during preforming that is larger than the measured value during steady molding A value setting device (72), a preforming shot number setting device (56) that sets the number of shots during preforming, and a preforming shot number counter (74) that counts the actual number of molding shots during preforming.
And a comparator (26) for comparing the number of preforming shots set in the preforming shot number setting device with the actual number of preforming shots detected by the preforming shot number counter.
If the comparator determines that the actual number of preforming shots is less than the set number of preforming shots, the set value of the preforming filling pressure setting device and the setting value of the preforming measurement value setting device are servo-controlled respectively. If the actual number of preforming shots is equal to the set number of preforming shots by inputting to the valve control unit and metering value control unit, the set value of the steady forming filling speed setting unit and the steady forming filling pressure setting unit are set. And a controller (48) for inputting the set value to the servo valve control device and for inputting the set value of the steady forming measurement value setter to the measurement value control device.

Further, in the case of the electric injection molding machine in which the plasticizing / measuring of the resin is performed by the plasticizing motor (80) and the injection of the molten resin is performed by the injection motor (81), the molding start-up control device is , A current detector (95) for detecting the current of the injection motor and a speed detector (28, for detecting the filling speed.
30) and a position detector (28, 6) that detects the screw position.
2), injection motor control device (94) that feedback-controls the operation of the injection motor according to the command from the setting device by signals from the current detector and speed detector, and plasticization by signals from the position detector Plasticizing motor control device (93) that controls the motor for motor to control the measured value of the molten resin according to the command from the setting device, and the steady molding filling speed setting device (50) that sets the filling speed during steady molding And the steady forming filling pressure setting device (52) that sets the filling pressure during steady forming, the steady forming measurement value setting device (70) that sets the weighing value during steady forming, and the filling pressure during steady forming Preforming filling pressure setting device (54) that sets the filling pressure during small preforming and preforming weighing value setter (72) that sets the weighing value during preforming that is larger than the weighing value during steady molding.
And a pre-forming shot number setting device (56) that sets the number of shots during pre-forming, a pre-forming shot number counter (74) that counts the actual number of molding shots during pre-forming, and a pre-forming shot number setting (26) that compares the number of preforming shots set in the container with the actual number of preforming shots detected by the preforming shot counter, and a preforming shot in which the actual number of preforming shots is set If the comparator determines that the number is less than the number, enter the setting value of the preforming filling pressure setting device and the setting value of the preforming measurement value setting device to the injection motor control device and the plasticization motor control device, respectively. When the actual number of preforming shots becomes equal to the set number of preforming shots, the set value of the steady forming filling speed setting device and the set value of the steady forming filling pressure setting device are injected. It has a controller (48) to be input to the plasticizing motor controller setting value in the steady molding weighing setter and inputs to the motor controller. The reference numerals in parentheses indicate the corresponding parts in the embodiments described later.

(E) Action At the time of start-up of molding, molding is performed for a predetermined number of pre-molding shots under pre-molding conditions. The preforming filling pressure of the preforming conditions is set to a pressure lower than the steady forming filling pressure. This is because the viscosity reduction of the molten resin in the screw cylinder during the interruption of molding and the variation in the temperature rise of each cavity in the hot runner mold having a large number of cavities are taken into consideration. Thereby, for example, even when the cavities are not well balanced, the molten resin smoothly flows into the entire mold without generating abnormal pressure. On the other hand, the pre-molding measured value is more than the steady-state molding measured value so that the insufficient amount of molten resin flowing out from the manifold can be taken into consideration and all the cavities in the mold can be completely filled without compensating for the insufficient amount. It is set large enough. Therefore, the molten resin is sufficiently filled in all the cavities of the mold from the first shot, and a molded product having a substantially predetermined shape can be obtained. Therefore, it is possible to take out by the automatic take-out machine. From the second shot onwards, even though the manifold is filled with molten resin, it will be weighed with the pre-formation weighing value, so more molten resin will be weighed than necessary, but since the filling pressure is low, it will be more than necessary. Filling, that is, so-called overpacking does not occur. The molten resin temperature stabilizes while molding is performed for the number of preforming shots under the preforming conditions, and the mold is in a heating state suitable for steady molding. When the number of preforming shots is completed, the preforming conditions are canceled and the steady forming conditions are switched. This enables automatic start-up of molding.

(F) Embodiment (First Embodiment) FIG. 1 shows a first embodiment of the present invention. The screw 12 provided in the cylinder 10 is rotationally driven by the hydraulic motor 14 and moves forward and backward integrally with the injection ram 18 in the injection cylinder 16. The hydraulic pressure from the hydraulic pressure source 42 is supplied to the oil chamber on the side where the injection ram 18 is moved forward through the pipe line 60. In addition,
The line 60 is provided with a servo valve 44, by which the hydraulic pressure and the oil amount are adjusted. The oil pressure in the injection cylinder 16 is detected by the pressure detector 20, and this signal is given to the servo valve controller 24 via the amplifier 22. Further, the moving speed of the screw 12 is detected by the encoder 28 and the amplifier 30, and this signal is also given to the servo valve control device 24.
The measurement value detection signal (a signal corresponding to the position of the screw 12) obtained by the encoder 28 and the amplifier 62 is input to the measurement value control device 64. Encoder 28 like this
Has two functions as a speed detector and a position detector. A predetermined setting signal is input from the controller 48 to the servo valve control device 24 and the measured value control device 64. Signals from the steady molding condition setting device 66 and the preforming condition setting device 68 are input to the controller 48. Steady molding condition setter
66 includes a steady forming filling speed setting device 50, a steady forming filling pressure setting device 52, and a steady forming measured value setting device 70.
Further, the preforming condition setting device 68 includes a preforming filling pressure setting device 54, a preforming measurement value setting device 72 and a preforming shot number setting device 56. The controller 48 is a comparator 26
A signal from either the steady molding condition setting device 66 or the preforming condition setting device 68 is output to the servo valve control device 24 and the measured value control device 64 based on the signal from the. Comparator 26
Is the actual preforming shot number counted by the preforming shot number counter 74 and the preforming shot number setting device.
The set value set in 56 is compared, and a signal is output to the controller 48 when the actual number of shots reaches the set value. The controller 48 outputs the signal from the preforming condition setting device 68 until the signal from the comparator 26 is input, and outputs the signal from the steady forming condition setting device 66 when the signal from the comparator 26 is input. To do. The preforming shot number counter 74 is reset by setting the operation mode of the injection molding machine to a mode other than the "fully automatic mode", and starts counting when preforming is started. The servo valve controller 24 outputs a signal for controlling the operation of the servo valve 44, and the metered value controller 64 outputs a signal for controlling the operation of the hydraulic motor 14.

In the first embodiment, the following operation is performed. Before starting the operation, the set values of the steady forming filling speed setting device 50, the steady forming filling pressure setting device 52 and the steady forming measured value setting device 70 of the steady forming condition setting device 66 are set to the steady forming condition values. Further, the preforming filling pressure setting device 54, the preforming measurement value setting device 72 and the preforming shot number setting device 56 of the preforming condition setting device 68 are set to the preforming condition values. The preforming filling pressure set value set in the preforming filling pressure setting device 54 is smaller than the steady forming filling pressure setting value set in the steady forming filling speed setting device 50. Further, the pre-forming metric value set value set in the pre-forming metric value setting device 72 is larger than the steady-forming metric value setting value set in the steady-forming metric value setting device 70. That is, the pre-forming measured value set value is a value obtained by adding the steady forming measured value set value to the shortage amount or more amount flowing out from the hot runner mold manifold. In the preforming shot number setting device 56, the number of shots until the cavity balance of the hot runner mold becomes stable is set. As described above, after the setting of each setter is completed, after measuring the set value of the preforming measurement value in the "manual mode" and setting the operation mode of the injection molding machine to the "fully automatic mode", the preforming condition setter is set. Preforming is started according to the preforming conditions set by 68. That is, the servo valve control device 24 controls the operation of the servo valve 44 so that a larger amount of molten resin than the steady molding condition is supplied to the mold manifold and the mold cavity at a filling pressure lower than the steady molding condition. Then, the hydraulic pressure supplied to the injection cylinder 16 is adjusted, and the measurement value control device 64 controls the rotation of the hydraulic motor 14. When the actual number of preforming shots counted by the preforming shot number counter 74 reaches the preforming shot number set value set in the preforming shot number setting device 56, the comparator 26 outputs a signal to the controller 48. ,
As a result, the controller 48 outputs the signal from the steady molding condition setting device 66 instead of the signal from the preforming condition setting device 68 to the servo valve control device 24 and the measured value control device 64. The servo valve controller 24 and the measured value controller 64 are the controller 48
The operations of the servo valve 44 and the hydraulic motor 14 are controlled on the basis of the steady molding conditions from the above. As a result, the steady molding conditions are automatically switched.

As described above, during preforming under the preforming conditions,
Since the filling pressure is lower than the steady molding conditions,
Even when the temperature of each cavity is not well balanced, the molten resin smoothly flows into the entire mold without generating abnormal pressure. In addition, since the preforming measured value is set to be larger than the steady forming measured value, all the cavities of the mold are sufficiently filled with the molten resin from the first preforming shot. Therefore, a molded product having a predetermined shape, which is not a semi-finished product, can be obtained, so that the automatic unloading machine can automatically take out from the preforming stage. Therefore, completely automatic molding start-up can be performed.

When the operation mode of the injection molding machine is changed to a mode other than the "full automatic mode" for the purpose of interrupting the molding, the preliminary molding shot number counter 74 is reset to 0, and the operation mode is set to the "full automatic mode" again. When starting, the preforming conditions are automatically switched to, and the same operation as above is performed.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention. The second embodiment is an application of the present invention to an electric injection molding machine.
That is, the rotation of the screw 12 is performed by the plasticizing motor 80, and the forward / backward movement of the screw 12 is performed by the injection motor 81. The rotation of the plasticizing motor 80 is transmitted to the screw 12 via the pulley 82, the belt 83, the pulley 84, the spline nut 85, and the spline shaft 86. The rotation of the injection motor 81 is controlled by the pulley 87, the belt 88, and the pulley.
The linear motion is converted via the 89, the rotating member 90, the ball nut 91 and the ball screw 92, and is transmitted to the screw 12.
The operation of the plasticizing motor 80 is controlled by the plasticizing motor control device 93, and the operation of the injection motor 81 is controlled by the injection motor control device 94. The injection motor control device 94 is provided with a current detector 95, and since the current detected by this corresponds to the axial force acting on the screw 12, the filling pressure is detected by the current detector 95. It Encoders other than the above 28, amplifier 30, amplifier 6
2, controller 48, comparator 26, preforming shot number counter 74, steady molding condition setting device 66, preforming condition setting device 68
The configuration such as is similar to that of the first embodiment shown in FIG.
Since the injection motor 81 includes the pulse encoder 81a, the screw position may be detected by this. In the second embodiment, the plasticizing motor 80 corresponds to the hydraulic motor 14 of the first embodiment, and the injection motor
81 corresponds to the injection cylinder 16. Therefore, if the plasticizing motor 80 and the injection motor 81 are controlled so as to correspond to the hydraulic motor 14 and the injection cylinder 16 at the time of start-up of molding, it is clear that the same operation as in the first embodiment can be obtained. .

(G) Effect of the Invention As described above, according to the present invention, a relatively large amount of molten resin is supplied at a relatively low filling pressure at the time of molding start-up to perform pre-molding, so that smoothness is achieved in each cavity. The so-called short shot due to the outflow of resin from the manifold of the hot runner mold is prevented while the molten resin is supplied to the hot runner die, and the automatic take-out machine can automatically take out from the first shot of preforming. This allows a smooth transition from the pre-molding conditions to the steady molding conditions,
Molding startup can be fully automated.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG. 2 is a diagram showing a second embodiment of the present invention. 10 …… Cylinder, 12 …… Screw, 14 …… Hydraulic motor, 16 …… Injection cylinder, 18 …… Injection ram, 20 …… Pressure detector, 24 …… Servo valve controller, 26 …… Comparison, 28 …
... Encoder (speed detector, position detector), 44 ... Servo valve, 48 ... Controller, 50 ... Steady molding filling speed setting device, 52 ... Steady molding filling pressure setting device, 54 ... Preforming filling pressure Setting device, 56 ... Preliminary molding shot number setting device, 64 ... Measurement value control device, 66 ... Steady molding condition setting device, 68 ... Preliminary molding condition setting device, 70 ... Steady molding measurement value setting device, 72 …… Preformation measurement value setter, 74 …… Preformation shot number counter, 80 …… Plastification motor, 81 …… Injection motor, 93 …… Plastification motor controller, 94 …… Injection motor Controller, 95 ... Current detector.

Claims (3)

[Claims] 1. A molding start-up control method for automatically switching to steady molding under steady molding conditions after performing preliminary molding under preset molding conditions for a set number of shots. Molding start-up control method for an injection molding machine in which a preforming filling pressure smaller than the filling pressure and a preforming measurement value larger than the steady molding condition measurement value are set. 2. A servo valve for controlling a hydraulic pressure and an amount of hydraulic oil supplied to an injection cylinder, a pressure detector for detecting a filling pressure, a speed detector for detecting a filling speed, and a position detector for detecting a screw position. And a servo valve control device that feedback-controls the operation of the servo valve according to the command from the setting device by the signals from the pressure detector and the speed detector, and the molten resin by controlling the rotation of the screw by the signal from the position detector. In the molding start-up control device of the injection molding machine, which has a weighing value control device that controls the weighing value of the molding machine according to the command from the setting machine, a steady molding speed setting device that sets the filling speed during steady molding, and a steady molding Steady molding Filling pressure setter that sets the filling pressure at the time, Steady molding weighing value setter that sets the weighing value at the steady molding, and less than the filling pressure at the steady molding Set the preforming filling pressure setting device that sets the filling pressure during preforming, the preforming measurement value setting device that sets the measurement value during preforming that is larger than the measurement value during steady molding, and the number of shots during preforming. Pre-forming shot number setting device to set, pre-forming shot number counter to count the actual forming shot number at pre-forming, pre-forming shot number set to pre-forming shot number setting device and pre-forming shot number counting Set the preforming fill pressure if the comparator determines that the actual number of preforming shots detected by the device is less than the number of preforming shots set. The set value of the pre-molding set value and the set value of the pre-formed measured value setter are input to the servo valve control unit and the measured value control unit, respectively, and the actual pre-forming shot number is set When the number of shots is equal to the number of shots, input the set value of the steady forming filling speed setting device and the set value of the steady forming filling pressure setting device to the servo valve controller, and set the set value of the steady forming measured value setting device to the measured value. A molding start-up control device for an injection molding machine, comprising: a controller for inputting to the control device. 3. A molding start-up control device for an injection molding machine, wherein plasticizing and measuring of resin is performed by a plasticizing motor, and injection of molten resin is performed by an injection motor.
The current detector that detects the current of the injection motor, the speed detector that detects the filling speed, the position detector that detects the screw position, and the operation of the injection motor by the signals from the current detector and the speed detector. Injection motor control device that performs feedback control according to the command from the setting device and plasticization motor that controls the plasticizing motor by the signal from the position detector to control the measured value of the molten resin according to the command from the setting device In a molding start-up control device for an injection molding machine having a motor control device, a steady molding filling speed setting device that sets the filling speed during steady molding and a steady molding filling pressure setting device that sets the filling pressure during steady molding And a steady forming metering value setter that sets the weighing value during steady forming, and a preforming charging unit that sets the filling pressure during preforming that is smaller than the filling pressure during steady molding. A balance pressure setting device, a pre-forming measurement value setting device that sets a measurement value during pre-molding that is larger than the measurement value during steady molding, a pre-forming shot number setting device that sets the number of shots during pre-forming, and a spare Pre-forming shot number counter that counts the actual number of forming shots at the time of forming, the number of pre-forming shots set in the pre-forming shot number setting device and the actual number of pre-forming shots detected by the pre-forming shot number counter And the comparator that compares the actual preforming shot number with the set number of the preforming filling pressure setter and the preforming measured value setter if the comparator determines that the actual number of preforming shots is less than the set number of preforming shots. If the actual number of preforming shots becomes equal to the set number of preforming shots by inputting the set values of the above into the injection motor controller and the plasticizing motor controller, respectively. Input the setting values of the steady forming filling speed setting device and the setting values of the steady forming filling pressure setting device to the injection motor control device and input the setting values of the steady forming measurement value setting device to the plasticizing motor control device. A molding start-up control device for an injection molding machine, comprising: a controller.