JPH06262660A - Method and device for heating nozzle of injection molding machine - Google Patents

Abstract

PURPOSE:To perform the optimum heating to an injection nozzle by axially dividing the injection nozzle into a plurality of heating zones and making the heating quantity to the foremost heating zone at a time of the touch with the nozzle larger than that at a time of the non-touch with the nozzle. CONSTITUTION:An injection nozzle 2 is axially divided into a plurality of heating zones Za, Ab. The heating quantity of the foremost heating zone Za is set so as to become larger than that at a time of the non-touch with the nozzle and the heating quantity of the other heating zone Zb is set to the same condition at both of a time of the non-touch with the nozzle and a time of the touch with the nozzle. In this case, the foremost heating zone Za is intermittently heated at the time of the non-touch with the nozzle and continuously heated at the time of the touch with the nozzle and the other heating zone Zb is desirably heated intermittently at both times.

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 equipped with an injection nozzle for injecting and filling 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 at the time of nozzle touch to the frontmost heating zone Za is set to be larger than the heating amount at the time of non-nozzle touch, and the other heating zones Zb are set. The heating amount is set to the same condition when the nozzle is not touched and when the nozzle is touched. In this case, the frontmost heating zone Za is intermittently heated during non-nozzle touch and is continuously heated during nozzle touch, and the other heating zone Zb is intermittently heated during non-nozzle touch and during nozzle touch. It is desirable to do.

Further, the nozzle heating device 1 of the injection molding machine according to the present invention is configured so that the heaters 3a and 3b attached in the axial direction of the injection nozzle 2 and the amount of power supplied to the frontmost heater 3a when the nozzle is touched are not controlled. A control function unit 4 is provided to control the power supply amount to be larger than the power supply amount when the nozzle is touched, and to control the power supply amount to the other heater 3b under the same condition during the non-nozzle touch and the nozzle touch. To do. In this case, the control function unit 4 is provided with a single temperature sensor 6 that detects the temperature of the injection nozzle 2, and based on the detection result of this temperature sensor 6, feedback control of the power supply amounts to all the heaters 3a and 3b can be performed simultaneously. In addition, it can be configured to include the voltage adjusting unit 7 that adjusts the magnitude of the applied voltage when the nozzle is touched to the frontmost heater 3a. Further, the control function unit 4 is the front heater 3a.
Power is intermittently supplied to the other heater 3 when the nozzle is not touched and continuously supplied when the nozzle is touched.
It is desirable to perform control to intermittently supply power to b in both the non-nozzle touch and the nozzle touch.

[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 4 first controls the plurality of heaters 3a and 3b according to a preset power supply condition (heating condition) at the time of non-nozzle touch, and at the time of nozzle touch, the power supply amount to the frontmost heater 3a. The (heating amount) is controlled so as to be larger than that when the nozzle is not touched.
The power supply amount (heating amount) of b is controlled so as to be the same as that in the non-nozzle touch. This compensates for the temperature drop in the heating zone Za due to the die contacting the tip of the injection nozzle 2. In this way, the heaters 3a and 3b are controlled to supply power by using the nozzle touch as a switching point.

It should be noted that all the heaters 3a and 3b are controlled by the control function unit 4 based on the temperature detected by the temperature sensor 6 provided in another heating zone Zb which is not affected by the contact of the mold.
Since the power supply amount (heating amount) to the heaters is feedback-controlled, the heaters 3a and 3b are simultaneously controlled by a single control system.

In this case, the control function unit 4 intermittently supplies power to the frontmost heater 3a during non-nozzle touch, and also continuously supplies power during nozzle touch, thereby corresponding heating zone Za. Heating is performed. In addition, to the other heater 3b, intermittent power supply is performed both when the nozzle is not touching and when the nozzle is touching, and the corresponding heating zone Zb is heated. At this time, the voltage adjusting section 7 adjusts the magnitude of the applied voltage to the heater 3a at the frontmost portion when the nozzle is touched to be optimum.

[0012]

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, reference numeral 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 fluctuation, 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 6 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, a temperature sensor 6 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 26 is connected to the power supply unit 26 via the open / close switches 22 and 23 and the voltage adjusting unit 7, and the heater 3a is connected to the power supply unit via the open / close switches 24 and 25 and the power supply adjusting unit 27. Connect to 26. Further, the heater 3b attached to the heating zone Zb is also connected to the power supply adjusting unit 27. On the other hand, 28 is a control unit, and the power supply unit
6 and the power supply adjusting unit 27, and the temperature sensor 6 is connected to the control unit 28. The open / close switches 22, 23, 24 and 25 are controlled by the control unit 28.

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, when the nozzle is not touched (the injection nozzle 2 is separated from the mold 13), the open / close switches 22 and 2 are used.
3 is open, and the open / close switches 24 and 25 are closed. As a result, power is supplied from the power supply controller 27 to both the heaters 3a and 3b under the same conditions (different conditions may be used) at the same time. Note that FIG. 3A shows a voltage waveform (voltage Vn) at the time of feeding power to the heater 3b, and FIG.
(B) is a voltage waveform (voltage V
n), and switched intermittent power supply is performed to each heater 3a, 3b.

In addition, at this time, the power supply adjusting unit 27 and the control unit 28 use the detected temperature detected by the temperature sensor 6 to supply power to the heaters 3a and 3b so that the heating temperature of the injection nozzle 2 becomes the set temperature. Feedback control. 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 addition,
In this case, the magnitude of the voltage may be controlled without changing the duty ratio.

On the other hand, when the nozzle is touched (when the injection nozzle 2 is in contact with the mold 13), the nozzle touch is detected by detecting the position of the injection nozzle 2 and the like, and at the point Pt shown in FIG. The open / close switches 22 and 23 are closed, and the open / close switches 24 and 25 are opened. As a result,
As shown in FIG. 3 (a), the amount of power supplied to the heater 3b continues under the same conditions, but the heater 3a is supplied with power from the voltage adjusting unit 7, and as shown in FIG. 3 (b), the voltage adjusting unit is supplied. Continuous power feeding is performed by the voltage Vs whose voltage is adjusted (lowered) by 7. In this case, the voltage adjustment unit 7
Thereby, the magnitude of the voltage Vs is preset so that the heating temperature of the heating zone Za in the injection nozzle 2 becomes optimum.

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 more than 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.

[0023]

As described above, according to the nozzle heating method for the injection molding machine of the present invention, when the injection nozzle is heated, the injection nozzle is divided into a plurality of heating zones in the axial direction, and the nozzle touch to the frontmost heating zone is performed. The heating amount during heating is set to be larger than the heating amount during non-nozzle touch, and the heating amounts for other heating zones are set to the same conditions during non-nozzle touch and during nozzle touch, and the injection molding according to the present invention is also performed. The nozzle heating device of the machine controls a plurality of heaters attached in the axial direction of the injection nozzle and the power supply amount at the time of nozzle touch to the frontmost heater to be larger than the power supply amount at the time of non-nozzle touch, and Since it has a control function unit that controls the amount of power supplied to the heater in the same condition both when the nozzle is not touching and when it is touching the nozzle, optimum heating for the injection nozzle Ukoto it is, 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 (Foremost Heater) 3b Heater (Other Heater) 4 Control Function Part 6 Temperature Sensor 7 Voltage Adjustment Unit Za Heating Zone (Frontmost Heating Zone) Zb Heating Zone (Other Heating) zone)

Claims (6)

[Claims] 1. When heating the injection nozzle, the injection nozzle is divided into a plurality of heating zones in the axial direction, and the heating amount at the time of nozzle touch to the frontmost heating zone is set to be larger than the heating amount at the time of non-nozzle touch. At the same time, the heating amount for other heating zones is set to the same condition both when the nozzle is not touched and when the nozzle is touched. 2. The foremost heating zone is intermittently heated during non-nozzle touch and is continuously heated during nozzle touch, while the other heating zones are intermittently heated during non-nozzle touch and nozzle touch. The method for heating a nozzle of an injection molding machine according to claim 1, wherein: 3. A plurality of heaters attached in the axial direction of the injection nozzle, and the power supply amount at the time of nozzle touch to the frontmost heater is controlled to be larger than the power supply amount at the time of non-nozzle touch, and another heater. A nozzle heating device for an injection molding machine, comprising a control function unit for controlling the amount of power supply to the same condition under non-nozzle touch and during nozzle touch. 4. The control function unit is provided with a single temperature sensor for detecting the temperature of the injection nozzle, and the power supply amount to all the heaters can be feedback-controlled simultaneously based on the detection result of the temperature sensor. The nozzle heating device of the injection molding machine according to claim 3. 5. The control function unit intermittently supplies power to a heater at the frontmost portion during non-nozzle touch and continuously supplies electric power to the other heater at the time of non-nozzle touch and nozzle touch. The nozzle heating device for an injection molding machine according to claim 3, wherein the control is performed to intermittently supply power. 6. 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 applied voltage when the nozzle touches the frontmost heater.