JPH0577302A - Method and apparatus for controlling temperature of heating cylinder in injection molding - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent overshoot in a zone with a small heat capacity, such as the nozzle at the tip of the heating cylinder. [Structure] The heating cylinder 1 is divided into a nozzle portion 3 at the tip and a heating cylinder body 4, the heating cylinder body 4 is further divided, and a band heater 5a is divided in the nozzle portion 3 of the heating cylinder body 4. Band heaters 5b are attached to the respective zones formed by the open portions. In each zone, one thermocouple 6a or 6b, one temperature controller 7a or 7b, and one magnetic contactor 8a or 8b are connected to each zone as a control unit that starts energizing the corresponding band heaters 5a and 5b from a predetermined time point. Has been done. Also, each temperature controller 7
For a and b, the set temperature can be set as data that defines the heating start time for each band heater 5a and 5b.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method and apparatus for controlling the temperature of a heating barrel of an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a heating cylinder is divided into a plurality of zones, band-shaped heaters (hereinafter referred to as band heaters) are attached to each zone, and the band heaters are collectively operated before starting a molding operation. An electric current was passed through to raise the temperature of the heating cylinder. Then, the temperature of the heating cylinder is controlled by cutting off the power supply to the band heater and stopping the heating in order from the zone where the temperature reaches the set temperature.

[0003]

In the above conventional control,
For example, a zone with a small heat capacity, such as the nozzle at the tip of the heating cylinder, reaches a set temperature and the band heater in this nozzle also has a large heat capacity even after the power supply to the band heater is stopped. Energization of the heater is continued. The heat applied by continuing the energization is also transmitted to the nozzle part that has already stopped heating, so that as shown in FIG. 3, the temperature T0 of the nozzle part is further increased even though the temperature 31 has reached the set value. The temperature rises abnormally (hereinafter referred to as overshoot) and becomes considerably higher than the temperature 32 of other zones. In this way, the temperature of at least a part of the zone such as the nozzle portion overshoots, which decomposes or carbonizes the resin remaining inside the zone, which has a problem that the molded product is adversely affected. ..

The present invention has been made in view of the above problems of the prior art, and prevents an abnormal overshoot in a zone having a small heat capacity, such as a nozzle portion at the tip of a heating cylinder.
An object of the present invention is to provide a heating cylinder temperature control method and device for an injection molding machine, which can obtain a normal molded product.

[0005]

In order to achieve the above object, a method of controlling a temperature of a heating cylinder of an injection molding machine according to the present invention is a method of controlling a temperature of a heating cylinder of an injection molding machine. It is characterized in that the heating start time is set such that the heating start time is delayed as the zone is divided into smaller zones.

The zone having a small heat capacity is generally the nozzle portion at the tip of the heating cylinder.

Further, the heating cylinder temperature control device of the injection molding machine of the present invention is a device for controlling the temperature of the heating cylinder of the injection molding machine, and is attached to each of the plurality of zones constituting the heating cylinder of the injection molding machine. A heater, a storage unit that stores data that defines a heating start time for each of the plurality of heaters, and a control unit that starts energizing the heater from a time determined by the data stored in the storage unit. It is characterized by having.

[0008]

When the temperature of the heating cylinder is raised before the operation of the injection molding machine is started, for example, in the nozzle portion at the tip of the heating cylinder, the zone having a small heat capacity rises rapidly and the zone having a large heat capacity rises slowly. Therefore, the time to reach the set temperature is different. Therefore, in the present invention, the heating start time is set so that the heating start time is delayed in a zone having a smaller heat capacity, and heating is started earlier in the zone having a large heat capacity, while the heating start is delayed in a zone having a small heat capacity, thereby heating the heating cylinder. Even in the zone such as the nozzle section at the tip, heat is applied from other zones to prevent overshoot.

[0009]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view showing an embodiment of the present invention.

As shown in FIG. 1, a heating cylinder 1 of an injection molding machine.
Is divided into a nozzle part 3 at the tip and a heating cylinder body 4,
The heating cylinder body 4 is further divided into four (the number of divisions is arbitrary).
Further, the band heater 5a is attached to the nozzle portion 3, and the band heater 5b is attached to each of the five zones of the heating cylinder main body 4 formed by the divided portions. Nozzle part 3
Each zone composed of the divided parts of the heating cylinder main body 4 is a nozzle part as a control part for starting energization to the corresponding band heaters 5a, 5b from a predetermined time point so that the temperature can be controlled independently. 3 for thermocouple 6a or thermocouple 6b for other zones, temperature controller 7a for nozzle section 3 or temperature controller 7b for other zones and electromagnetic contactor 8a for nozzle section 3 or for other zones Each of the electromagnetic contactors 8b is electrically connected.
The electromagnetic contactor 8b is omitted from the drawings except for the zone closest to the nozzle portion 3 among the zones of the heating cylinder body 4. Each of the temperature controllers 7a and 7b is connected to a circuit power source (not shown) via the control circuit switch 2, and the temperature controller for one of the temperature controllers 7a and 7b, that is, for the nozzle unit 3. The contact 7 separates 7a and the temperature controllers 7b for the other four zones. Further, the temperature controllers 7a and 7b are capable of setting the set temperatures as data defining the heating start time for the band heaters 5a and 5b, respectively, and also operate as storage units.

Next, the operation of this embodiment will be described.

When the operator turns on the control circuit switch 2, the required temperature is set in each of the temperature controllers 7a and 7b. Next, the temperature of each zone of the heating cylinder 1 is measured by the thermocouples 6a and 6b of each zone.

At the time of start-up, first, each zone other than the nozzle section 3,
That is, the electromagnetic contactors 8b corresponding to the respective divided parts of the heating cylinder main body 4 are turned on, respectively, and heating is started by the heat generated by passing an electric current through the band heater 5b connected to each electromagnetic contactor 8b. Of the divided parts of the heating cylinder body 4, for example, after confirming that the temperature of the part closest to the nozzle part 3 has reached the set temperature of the temperature controller 7b by the corresponding thermocouple 6b, the nozzle part 3 The temperature control of the nozzle unit 3 is started by turning on the corresponding electromagnetic contactor 8a and supplying a current to the band heater 5a connected to the electromagnetic contactor 8a to heat the nozzle unit 3.

As a result, as shown in FIG. 2, the temperature 21 of the nozzle portion 3 and the temperature 2 of the other zones of the heating cylinder body 4 are set.
Since 2 is substantially the same, the nozzle portion 3 at the tip of the heating cylinder 1 is also given heat from other zones and does not overshoot.

Although the temperature of the zone closest to the nozzle portion 3 is used as a reference for starting heating of the nozzle portion 3 here, the timer is activated from the start of heating of each zone of the heating cylinder body 4, and the nozzle portion 3 is timed up. The temperature may be controlled so as to start the heating.

Further, the time points at which the heating of the nozzle portion 3 and the other zones are started may be staggered so that the time points at which the respective set temperatures are reached are substantially the same.

[0018]

Since the present invention is configured as described above, it prevents abnormal overshoot in a zone having a small heat capacity, such as a nozzle at the tip of a heating cylinder, and decomposes resin remaining in the zone. Alternatively, it is possible to produce a normal molded product without carbonization.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a temperature rise curve diagram of each part of the heating cylinder in the present embodiment.

FIG. 3 is a temperature rise curve diagram of each part of a heating cylinder in a conventional example.

[Explanation of symbols]

 1 Heating Cylinder 2 Control Circuit Switch 3 Nozzle Part 4 Heating Cylinder Main Body 5a, 6b Band Heater 6a, 6b Thermocouple 7a, 7b Temperature Controller 8a, 8b Magnetic Contactor 9 Contact

Claims (3)

[Claims] 1. A method for controlling a temperature of a heating cylinder of an injection molding machine, wherein the heating cylinder is divided into a plurality of zones, and a heating start time is set so that a zone having a smaller heat capacity delays the heating start time. A method for controlling a heating cylinder temperature of an injection molding machine. 2. The heating cylinder temperature control method for an injection molding machine according to claim 1, wherein the zone having a small heat capacity is the nozzle portion at the tip of the heating cylinder. 3. An apparatus for controlling the temperature of a heating cylinder of an injection molding machine, wherein a heater attached to each of a plurality of zones forming the heating cylinder of the injection molding machine, and a heating start time point for each of the plurality of heaters. Heating cylinder temperature of an injection molding machine, comprising: a storage unit for storing data defining the above, and a control unit for starting energization of the heater from a time determined by the data stored in the storage unit. Control device.