JP2602135B2 - Cold start prevention control method for injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine, and more particularly to an injection molding machine for shortening a heating time from turning on a power supply of a heater for heating a barrel of an injection apparatus to completion of the heating of the barrel temperature. A cold start prevention control method for an injection molding machine.

[0002]

2. Description of the Related Art After a molten resin is injected into a mold cavity by driving an injection device, and once the power supply of the barrel heating heater is turned off while the molten resin remains in the injection device, the molten resin solidifies. To start. When the power supply for heating the barrel is turned on again after a certain period of time, the solidified residual resin starts remelting. However, if the screw is rotated before the residual resin at the front of the screw head in the barrel is completely remelted, the screw may be twisted or bent. The cold start prevention control performed to prevent such a phenomenon is performed after a lapse of a predetermined time from the time when the temperature of the front part of the screw head in the barrel becomes a measured value ≧ (set value−lower limit value). The heating of the barrel temperature was completed.

[0003]

However, in the conventional cold start prevention control, the temperature of the front portion of the screw head when the power supply of the barrel heating heater is turned on may be the measured value ≒ the set value. Regardless of the actual measurement value 測 setting value-lower limit value,
Since the time from turning on the power supply for the barrel heater to the completion of the rise in the barrel temperature was kept constant, the power supply to the barrel heater was continued even though the resin was completely re-melted. Wasting wasted power and time. In particular, in the case of the actual measurement value ≒ the set value, there is a problem that it is remarkable and wasteful.

[0004]

In order to solve such a problem, according to the present invention, A, B, and C are used to measure the temperature measured in front of the screw head in the barrel when the power supply for heating the barrel of the injection device is turned on. When the measured temperature is in the A zone lower than the cold start prevention timer start lower limit lower than the cold start prevention timer at least which indicates the temperature state in which the screw can be started, the remaining time in which the screw can be started is displayed on the display screen. When the measured temperature reaches the cold start prevention timer start lower limit value, the remaining time during which the screw can be started is displayed on the display screen, and the measured temperature is used to prevent the cold start prevention. When in the B zone which is higher than the lower limit for timer start and lower than the temperature set value at which the re-melting state of the resin is exhibited more than the lower limit for cold start prevention timer,
The maximum value of the cold start prevention timer is calculated proportionally according to the difference between the temperature set value and the measured temperature value, and a value is displayed on the display screen as the cold start prevention remaining time. When the temperature is less than the minimum value, the value of the cold start prevention timer minimum value is displayed on the display screen as the cold start prevention remaining time. The minimum value of the cold start prevention timer is displayed on the screen as the remaining time of the cold start prevention, and when the remaining time of the cold start prevention remaining in the B zone and the C zone becomes 1 minute, the nozzle and the barrel are stopped. If the actual temperature measured by the temperature detector located in the area is within the vertical range provided for the predetermined temperature set point, the display on the display screen will disappear and the cold start prevention will be released I'll do it It was.

[0005]

[Function] In order to know the re-melting state of the resin reservoir at the front of the screw head when the power supply for heating the barrel is turned on again, the measured temperature values detected are divided into three zones A, B and C and displayed in each zone. By managing the remaining time of the cold start prevention on which the screw start can be started on the screen, it is possible to return to the normal injection operation in a short time.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a control method for preventing cold start in injection molding according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a front view of a part of the injection device in section, FIG. 2 is a display screen for displaying a remaining time at which the screw can be started,
FIG. 3 is an explanatory view divided into three zones for confirming the position of the measured temperature value at the front part of the screw head when the power supply for heating the barrel is turned on.

In FIG. 1, an injection device 1 includes nozzles 2
Barrel 3, hopper 4, screw 7, motor 8, and
It comprises a nozzle 2 and a heater 10 for heating the barrel 3. The heater 10 has a configuration in which the nozzle 2 is divided into two sections and can be heated by the nozzle heaters 1H and 2H, and the barrel 3 is divided into four sections to increase the barrel temperature. Heaters 3H, 4H, 5
H and 6H are provided so as to be heatable. A temperature detector such as a thermocouple (not shown) is attached to each of the barrel heating heaters 1H to 6H so that actual measured values of the temperature of the nozzle 2 and the barrel 3 can be detected. The temperature can be set so that the nozzle 2 and the barrel 3 have desired temperatures.

Now, the resin supplied from the hopper 3 is melted in the barrel 3 by receiving the thermal energy transmitted from the heater 10 and the shear energy by the transfer action of the screw 7. The injection device 1 accumulates resin in a gap formed in the front part of the head when the screw 7 retreats during the metering operation, which is a stage before the injection process. When the measurement is switched to the injection step from the state where the measurement is completed, the screw 7 advances without rotating and the molten resin is injected into the cavity formed between the dies, and then the dies are cooled to take out the product. It is. During such repetition, the injection unit is temporarily stopped due to a power failure or unavoidable reason, but after the stop condition is released, the heater power for the injection unit is turned on again.
The nozzle 2 and the barrel 3 are reheated until the normal injection operation is possible.

During such a series of operations of injection operation → heater power-off → return treatment → heater power supply → reinjection operation,
Particularly, in the present invention, the temperature is monitored as shown in FIGS. 2 and 3 for the purpose of shortening the time during which the power can be re-injected after the power is turned on again when the screw 7 is rotated in accordance with the re-injection operation. The screw is prevented from being twisted or bent. In particular, when the molten resin once solidified in the injection device 1 is to be re-melted, a necessary condition is that the resin staying in the front portion of the screw head having the largest pool of resin in the barrel 3 has been completely re-melted. . Therefore, after the temperature detected by the thermocouple attached to the heating heater 3H reaches at least the temperature at which the screw 7 can be started to be started, that is, the lower limit for starting the cold start prevention timer, the desired temperature is further increased. Heating is continued until the value falls within the upper and lower limits provided before and after the set value.

That is, it is sufficient that the temperature in the resin reservoir at the front portion of the screw head has reached at least the upper and lower limit width of the desired temperature set value. This is because the remaining portion of the barrel 3 generally has little resin pool and stays in a portion where the gap between the screw 7 and the barrel 3 is small. This is because if the temperature of 10 rises, the heat from the barrel 3 can be easily transmitted, and the resin once solidified can be easily re-melted.

The details will be described with reference to FIG. The transition of the measured temperature value of the heater 3H after the power supply to the barrel heating heater is turned on will be described for three zones A, B, and C. (1) A zone; that is, when the measured temperature value <(temperature set value−lower limit value for starting the cold start prevention timer), the measured temperature value ≧ (temperature set value−lower limit value for starting the cold start prevention timer) ), The cold start prevention remaining time 23 is not displayed on the display screen 21 as shown in FIG.
However, when the measured temperature value ≧ (temperature set value−lower limit value for starting the cold start prevention timer), the maximum value of the cold start prevention timer is displayed on the display screen 21 in minutes, and the remaining time 23 of the cold start prevention is displayed. . Thereafter, each time one minute elapses, the cold start prevention remaining time 23 on the display screen 21 is decremented by one minute. Here, when the remaining time 23 for the cold start prevention becomes 1 minute remaining, all other zones (1H other than the heater 3H,
The actual measured values of the temperature detectors provided at the 2H, 4H, 5H and 6H) are compared with the temperature set values provided at the respective zones, and all zones (1H to 6H) are compared.
Satisfies the condition of actual measured value ≧ (temperature set value−upper / lower limit width), the cold start prevention time 23 on the display screen 23 disappears, the temperature rise of the barrel 3 is completed, and the start of the screw 7 starts. It becomes possible. Here, when the present invention is implemented, if the measured temperature value is lower than the cold start prevention timer start lower limit value, the cold start prevention remaining time 23 is not displayed on the display screen 21.
When the measured temperature reaches the lower limit for starting the cold start prevention timer, the cold start prevention remaining time 23 is displayed on the display screen 21 as 10 minutes, and the cold start prevention on the display screen 21 is displayed every minute. The remaining time 23 is subtracted. When the cold start prevention remaining time reaches one minute, the cold start prevention remaining time is displayed on the display screen 21 as one minute. Further, when the measured temperature values of all the zones (1H to 6H) fall within the upper and lower limits set for the predetermined temperature set value, the display on the display screen 21 disappears, and the cold start prevention is released. You.

(2) Zone B: (Temperature setting value-Lower limit value for cold start prevention timer activation) ≦ (Temperature measured value)
If ≤ (temperature set value), a value obtained by proportionally dividing the maximum value of the cold start prevention timer by the difference between the temperature set value and the measured temperature value is displayed on the display screen 21 as the cold start prevention remaining time 23. It has become.

[0013]

(Equation 1)

However, if the result of the calculation is equal to or less than the minimum value of the cold start prevention timer, the value of the minimum value of the cold start prevention timer is displayed on the display screen 21 as the remaining time 23 of the cold start prevention. Thereafter, every time one minute elapses, the cold start prevention remaining time 23 on the display screen 21 is decremented by one minute. When the cold start prevention remaining time 23 becomes one minute remaining, the measured temperature values of all the zones other than the heater 3H are compared with the set temperature values, and the measured temperature values of all the zones (1H to 6H) ≧ When the temperature set value-the upper / lower limit width is reached, the cold start prevention remaining time 23 on the display screen 21 disappears, the temperature rise of the barrel 3 is completed, and the start of the screw 7 can be started. Here, when the present invention is carried out, the temperature set value is 200 ° C. The measured temperature value is 185 ° C. The lower limit value for starting the cold start prevention timer 30 ° C. The maximum value for the cold start prevention timer is 10 minutes The minimum value for the cold start prevention timer is 2 minutes In some cases, the cold start prevention remaining time is [(200 ° C.-1
85 ° C.) / 30 ° C.] × (10 minutes−2 minutes) +2 minutes, which is 6 minutes. Therefore, the cold start prevention remaining time 23 is displayed on the display screen 21 as 6 minutes. However, when the calculation result is 2 minutes or less, the cold start prevention remaining time 23 is displayed on the display screen 21.
Is displayed as 2 minutes, and each time 1 minute elapses, the cold start prevention remaining time 23 on the display screen 21 is subtracted. Next, when the measured temperature values of all the zones (1H to 6H) fall within the upper and lower limits provided for the predetermined temperature set value, the display on the display screen 21 disappears and the cold start prevention is released. You.

(3) C zone; that is, temperature set value <
In the case of the measured temperature value, the cold start prevention timer minimum value is displayed on the display screen 21 as the cold start prevention remaining time 23. Thereafter, every time one minute elapses, the cold start prevention remaining time 23 on the display screen 21 is decremented by one minute. When the cold start prevention remaining time 23 becomes one minute remaining, the measured temperature values of all other zones (zones of 1H to 6H other than the heater 3H) are compared with the temperature set values, and all zones (1H to 6H) are compared.
Is less than the actual measured value ≧ temperature set value−upper / lower limit width, the cold start prevention remaining time 23 on the display screen 21 disappears,
The temperature rise of the barrel 3 is completed, and the start of the screw 7 can be started. Here, when the present invention is implemented, the cold start prevention remaining time 23 on the display screen 21 is displayed as 2 minutes, and the cold start prevention remaining time 23 on the display screen 21 is subtracted every one minute. You. Next, all zones (1H-6
When the measured temperature H) falls within the upper and lower limits provided for the predetermined temperature set value, the display on the display screen 21 disappears and the cold start prevention is released.

In the above description, for example, the injection device 1 used for an injection mold clamping device of 350 tons has been described. In the case of the injection device 1 used for an injection mold clamping device of, for example, 1300 tons, the diameter of the barrel 3 becomes large. Therefore, the amount of resin pool in the front part of the screw head also increases. For this reason, the heating of the barrel 3 is temporarily stopped, and the cold start prevention remaining time 23 is increased to, for example, 30 minutes when the power supply for heating the barrel is turned on again. As described above, since the cold start prevention remaining time 23 changes depending on the size of the injection device 1 and the kind of resin, etc., if various experiments are performed in advance to accumulate data, the implementation becomes easy and great results are obtained. Can be

[0017]

As is apparent from the above description, according to the present invention, the measured values of the temperature in front of the screw head in the barrel at the time of turning on the power supply for heating the barrel of the injection device are A, B, and C. When the actual measured temperature is in the A zone where the measured temperature value is at least lower than the cold start prevention timer start lower limit value that indicates the temperature state at which the screw can be started, the remaining time during which screw start can be started is displayed on the display screen. When the measured temperature reaches the lower limit for activating the cold start prevention timer, the remaining time during which the screw can be activated is displayed on the display screen, and the measured temperature is used to activate the cold start prevention timer. When it is in the B zone that is higher than the lower limit value for use and lower than the temperature set value at which the resin has re-melted more than the lower limit value for starting the cold start prevention timer, the cold start prevention is calculated. The value obtained by proportionally dividing the maximum timer value by the difference between the temperature set value and the measured temperature value is displayed on the display screen as the remaining time for cold start prevention, and the calculation result is less than the minimum value for the cold start prevention timer. In this case, the cold start prevention timer minimum value is displayed on the display screen as the cold start prevention remaining time. When the measured temperature is in the C zone higher than the temperature set value, the cold start is displayed on the display screen. The minimum value of the prevention timer is displayed as the cold start prevention remaining time,
Further, when the remaining time of the cold start prevention in the B zone and the C zone becomes one minute remaining, the actual temperature measured by the temperature detectors disposed in the nozzle and the barrel is set to a predetermined temperature set value. If it is within the vertical width provided for, the display on the display screen disappears and the cold start prevention is canceled, so that the injection operation can be started in a short time and safely.

[Brief description of the drawings]

FIG. 1 is a front view of an injection device according to an embodiment of the present invention.

FIG. 2 is a display screen for displaying a remaining time at which a screw can be started to start according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram for displaying a relationship between a cold start prevention remaining time and a measured temperature value.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Injection apparatus 2 Nozzle 3 Barrel 4 Hopper 7 Screw 8 Motor 10 (1H, 2H, 3H, 4H, 5H, 6H) Heating heater 21 Display screen 23 Cold start prevention remaining time

Claims (1)

(57) [Claims] 1. An actual measured value of a temperature in front of a screw head in a barrel when a power supply of a heater for heating a barrel of an injection device is turned on is represented by A,
Divided into three zones B and C, and measured temperature is at least
Cold start prevention tab that shows the temperature condition at which the screw can be started
Display screen when in zone A which is lower than the lower limit for Ima activation
Do not display the remaining time at which screw startup can start.
So that the measured temperature value starts the cold start prevention timer.
When the lower limit is reached, the remaining screw
The time is displayed and the measured temperature is
The cold start protection is higher than the lower limit for starting the
The resin re-melts more than the lower limit for starting the stop timer.
When in the B zone lower than the set temperature,
Set the maximum value of the cold start prevention timer to the temperature set value and the temperature measured value.
The value proportionally proportional to the difference from the
Display as time and cold start of calculation result
When the time falls below the minimum value of the prevention timer, a cold
The value of the minimum value of the start prevention timer is used as the remaining time of the cold start prevention.
Display, C zone where actual measured value is higher than temperature set value
Is on, the minimum value of the cold start prevention timer is displayed on the display screen.
Is displayed as the cold start prevention remaining time, and
Cold start prevention remaining in zone B and zone C
When the remaining time is 1 minute, distribute to the nozzle and barrel.
The actual temperature measured by the installed temperature detector is determined in advance.
Within the upper and lower widths set for the set temperature
The display on the display screen disappears and the cold start prevention is released.
Cold start prevention control method in an injection molding machine, characterized in that it has to be.