JPH07108545B2 - Nozzle heating method and apparatus 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 a nozzle heating method and apparatus for an injection molding machine suitable for heating an injection nozzle.

[0002]

2. Description of the Related Art Generally, a heating cylinder of an injection device in an injection molding machine is provided with an injection nozzle for injecting and filling a molten resin in the heating cylinder into a mold cavity. A nozzle heating device is attached to maintain the molten resin in a desired molten state.

By the way, maintaining the tip temperature of the injection nozzle at an appropriate temperature is extremely important from the viewpoint of stable molding. For example, if the temperature is too high, "drulling" may occur or the temperature may rise. If is too low, the injection nozzle will "clog". On the other hand, the temperature distribution in the axial direction of the injection nozzle is as shown in FIG. As is clear from the figure, the temperature of the middle portion of the injection nozzle is feedback-controlled based on the actual measurement temperature detected by the temperature sensor, so that the temperature is maintained at the set temperature Ts. 100 ~ 20 than the temperature of the nozzle
Since the mold is abutted (nozzle touch) so as to be lowered by about 0 ° C., the temperature greatly changes between the non-nozzle touch and the nozzle touch. That is, when the nozzle is not touched, the temperature drop is relatively small as shown by the temperature distribution curve M1, but when the nozzle is touched, the temperature is drastically decreased as shown by the temperature distribution curve M2. The temperature distribution curve M3
Indicates the temperature when passing through the resin.

Therefore, conventionally, in order to prevent the adverse effect caused by such temperature fluctuation, it is also possible to set a plurality of temperature control regions in the axial direction of the injection nozzle and individually control the temperature in each set temperature control region. (See, for example, Japanese Utility Model Laid-Open No. 63-154210).

However, since such a conventional method requires a plurality of independent control devices, a plurality of temperature sensor components and control system components are also required.
There was a drawback that the cost was significantly increased.

The present invention has solved the problems existing in the prior art as described above, and provides an injection molding machine capable of optimally heating an injection nozzle and significantly reducing the cost. A nozzle heating method and apparatus are provided.

[0007]

A method for heating a nozzle of an injection molding machine according to the present invention includes:
The injection nozzle 2 is divided into a plurality of heating zones Za and Zb in the axial direction, the heating amount for the frontmost heating zone Za is set to be larger than the heating amounts for the other heating zones Zb, and the detected temperature of the other heating zones Zb is set. It is characterized in that the heating amounts of all the heating zones Za and Zb are simultaneously feedback-controlled based on the above. In this case, it is desirable to heat each heating zone Za, Zb intermittently.

Further, the nozzle heating device 1 of the injection molding machine according to the present invention has a plurality of heaters 3a and 3b attached in the axial direction of the injection nozzle 2 and the power supply amount to the frontmost heater 3a to the other heater 3b. The heaters 3a and 3b are controlled to be larger than the power supply amount, and all the heaters 3a and 3b are based on the temperature detected by a single temperature sensor 4 provided on the other heater 3b side.
It is characterized by comprising a control function unit 5 for simultaneously performing feedback control of the power supply amount to In this case, it is desirable that the control function section intermittently supply power to the heaters 3a and 3b, and if necessary, the control function section can be configured to include a voltage adjusting section 6 that adjusts the magnitude of the voltage applied to the other heater 3b.

[0009]

According to the nozzle heating method and apparatus 1 for the injection molding machine according to the present invention, a plurality of heating zones Za and Zb are set in the axial direction of the injection nozzle 2. Then, the control function unit 5 controls the power supply amount to the frontmost heater 3a to be larger than the power supply amount to the other heaters 3b, so that heating caused by the die contacting the tip of the injection nozzle 2 is performed. The temperature drop in zone Za is compensated. In addition, the control function unit 5 supplies power to all the heaters 3a and 3b (heating amount) based on the temperature detected by a single temperature sensor 4 provided in another heating zone Za that is not affected by the contact of the mold. Amount) is feedback-controlled, so that each heater 3a,
3b is simultaneously controlled by a single control system.

In this case, each heater 3 is controlled by the control function unit 5.
Power is intermittently supplied to a and 3b to heat the corresponding heating zones Za and Zb, and the voltage adjusting section 6 adjusts the magnitude of the applied voltage to the other heaters 3b to be optimum. It

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the structure of the nozzle heating apparatus 1 according to the present invention will be described with reference to FIGS.

In FIG. 1, 10 is an injection device in an injection molding machine. The injection device 10 includes a heating cylinder 11, the screw 12 is inserted into the heating cylinder 11, and the injection nozzle 2 is provided at the tip of the heating cylinder 11. In addition, 13 is a die, and 14 is a heater (band heater or the like) attached to the heating cylinder 11.

The injection nozzle 2 is provided with the nozzle heating device 1 according to the present invention. First, the injection nozzle 2 is divided into two front and rear heating zones Za and Zb in the axial direction, and a heater 3 using a band heater or the like is provided in each heating zone Za and Zb.
a and 3b are attached respectively. In this case, the front heating zone Za is set at the forefront of the injection nozzle 2 having large temperature fluctuations, and the rear heating zone Zb is set at the heating zone Z.
It is set to the entire injection nozzle 2 except a. Further, a temperature sensor 4 using a thermocouple or the like is attached to a substantially central portion in the axial direction of the injection nozzle 2 (a portion where the heater 3b is attached). On the other hand, a temperature controller 21 is provided, and this temperature controller 21
To each of the heaters 3a and 3b, the temperature sensor 4 is connected.

Next, a specific structure of the temperature controller 21 will be described with reference to FIG. Heating zone Za
The heater 3a attached to the power supply unit 23 is connected to the power supply unit 23 via the power supply adjusting unit 22. Further, the heater 3b attached to the heating zone Zb is connected to the power supply adjusting unit 22 via the voltage adjusting unit 6. On the other hand, reference numeral 24 is a control unit, which is connected to the power supply unit 23 and the power feeding control unit 22, and the temperature sensor 4 is connected to the control unit 24.

Next, the operation of the heating device 1 including the nozzle heating method according to the present invention will be described with reference to FIGS. 2 and 3.

First, the power supply adjusting section 22 intermittently supplies power to the heater 3a with a voltage Vf as shown in FIG. 3 (b). On the other hand, the voltage V output from the power supply controller 22
f becomes a low voltage through the voltage adjusting unit 6, and the voltage Vs (Vs <Vf) as shown in FIG.
Intermittent power supply. In this case, the voltage adjusting unit 6 presets the magnitude of the voltage Vs so that the heating temperature of the heating zone Za becomes optimum.

At this time, the power supply controller 22 and the controller 24 use the detected temperature detected by the temperature sensor 4 so that the heaters 3a and 3b are supplied with power so that the heating temperature of the injection nozzle 2 becomes the set temperature. Feedback control at the same time. That is, when the heating temperature is lower than the set temperature, the energization time in the intermittent power supply is lengthened, thereby increasing the duty ratio of the power supply waveform and, when the heating temperature is higher than the set temperature, the energization time. To shorten the duty ratio of the power supply waveform. In this case, the magnitude of the voltage may be controlled without changing the duty ratio.

Such control is performed in both the non-nozzle touch state and the nozzle touch state, and the temperature drop in the heating zone Za due to the die 13 coming into contact with the tip of the injection nozzle 2 is compensated. . In addition, each heater 3 is based on the temperature detected by a single temperature sensor 4 provided in another heating zone Za that is not affected by the contact of the mold 13.
a and 3b are simultaneously controlled by a single control system.

Therefore, the heating temperature of the heating zone Za at the time of touching the nozzle is improved as shown by the temperature distribution curve M4 shown in FIG. 5, and the optimum heating in which the temperature drop is suppressed as compared with the temperature distribution curve M2 in the prior art. The temperature is set, and such a heating temperature is realized by a single control system. FIG. 4 shows the temperature change of the injection nozzle 2 with time, Ta is the heating temperature in the heating zone Za, and Tb is the heating temperature in the heating zone Zb. It should be noted that the Pt point indicates the starting point of the nozzle touch, the Pf point indicates the time immediately before the injection, and the Pb point indicates the time immediately after the injection. Further, in the figure, the dotted line Tas shows the temperature change under the conventional technique.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, the case where the power supply to the heater is performed intermittently is illustrated, but all the power supply may be performed continuously. Further, there may be a plurality of other heating zones and other heaters. Furthermore, the power supply unit may be either a DC power supply or an AC power supply, and in the case of an AC power supply, the voltage waveform of FIG. 3 becomes a gate waveform of the AC voltage. In addition, the detailed configuration, shape, method, and the like can be arbitrarily changed without departing from the scope of the present invention.

[0022]

As described above, according to the nozzle heating method for the injection molding machine of the present invention, when heating the injection nozzle, the injection nozzle is divided into a plurality of heating zones in the axial direction, and the heating amount for the frontmost heating zone is set. Is set to be larger than the heating amount for other heating zones, and the heating amounts of all heating zones are simultaneously feedback-controlled based on the detected temperatures of the other heating zones, and the nozzle heating device of the injection molding machine according to the present invention is also provided. Is controlled so that the amount of power supplied to a plurality of heaters attached in the axial direction of the injection nozzle and the heater at the forefront is greater than the amount of power supplied to other heaters, and a single temperature provided on the other heater side is controlled. Since it has a control function part that simultaneously feedback-controls the power supply amount to all heaters based on the temperature detected by the sensor, it performs optimal heating for the injection nozzle. It is possible, a marked effect of being able to achieve significant cost reduction since it is sufficient a single control system in addition.

[Brief description of drawings]

FIG. 1 is a peripheral configuration diagram of an injection nozzle including a nozzle heating device according to the present invention,

FIG. 2 is a block diagram of the nozzle heating device,

FIG. 3 is a power supply waveform diagram for a heater in the nozzle heating device,

FIG. 4 is a temperature change diagram of an injection nozzle heated by the nozzle heating device over time;

FIG. 5 is a temperature distribution curve diagram in an axial direction in the injection nozzle,

[Explanation of symbols]

 1 Nozzle Heating Device 2 Injection Nozzle 3a Heater (Front Heater) 3b Heater (Other Heater) 4 Temperature Sensor 5 Control Function Section 6 Voltage Adjusting Section Za Heating Zone (Front Heating Zone) Zb Heating Zone (Other Heating) zone)

Claims (5)

[Claims] 1. When heating the injection nozzle, the injection nozzle is divided into a plurality of heating zones in the axial direction, the heating amount for the frontmost heating zone is set to be larger than the heating amount for other heating zones, and A method for heating a nozzle of an injection molding machine, wherein the heating amount of all heating zones is simultaneously feedback-controlled based on the detected temperature of the heating zones. 2. The nozzle heating method for an injection molding machine according to claim 1, wherein each heating zone is heated intermittently. 3. A plurality of heaters attached in the axial direction of the injection nozzle, and a power supply amount to the frontmost heater is controlled to be larger than a power supply amount to another heater, and a single heater provided on the other heater side. A nozzle heating device for an injection molding machine, comprising a control function unit that simultaneously feedback-controls the amount of power supplied to all heaters based on the temperature detected by one temperature sensor. 4. The nozzle heating device for an injection molding machine according to claim 3, wherein the control function section intermittently supplies power to each heater. 5. The nozzle heating device for an injection molding machine according to claim 3, wherein the control function unit includes a voltage adjusting unit for adjusting the magnitude of the voltage applied to the other heater.