JPH07156235A - Heat control device for injection molding machine - Google Patents

Abstract

PURPOSE:To prevent the breakage of a screw head and prevent the resin burning in an injection molding machine. CONSTITUTION:A heating cylinder 11 is divided in a metering section zone 16, a compression section zone 17 and feed section zone 18 successively starting from the front end. Heating cylinders are heated respectively in respective zones by heaters 19. The temperature of heating cylinders is sensed in respective zones by thermocouples 21. The heaters are controlled by a temperature controller based on the set temperature of respective zones and the sensed temperature of respective zones. When the sensed temperature of the metering section zone reaches the set temperature of the metering section zone, the set temperature of the feed section zone is set to temperature lower by a preset temperature by a temperature adjustment device, and the set temperature of the feed section zone is restored to the original temperature after the preset time is passed. A screw is set in the case of being driven rotatably after a specific time has passed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating control device for an injection molding machine, and more particularly to a method for preventing resin burning in a heating cylinder provided in the injection molding machine.

[0002]

2. Description of the Related Art Generally, in an injection molding machine, a resin is melted (plasticized) by a heating cylinder and then a screw is driven forward to inject the molten resin into a mold. In such an injection molding machine, when melting the resin in the heating cylinder, it is necessary to accurately control the heating temperature throughout the heating cylinder.

Conventionally, in heating control of a heating cylinder, the heating cylinder is divided into a plurality of zones, a heating temperature is set for each zone, and energization to a plurality of heaters is controlled based on these heating temperatures. Specifically, the temperature is detected for each zone, the heater is turned on until the detected temperature reaches the set heating temperature (target temperature), and when the target temperature is reached, the heater is turned on / off according to the detected temperature. There is.

In such heating control, in particular, in the initial stage of heating, the temperature rises in each zone according to its characteristics (balance between temperature rising ability and heat radiation amount). Therefore, from the viewpoint of preventing the screw head from being damaged, the screw is not driven until the heating cylinder is sufficiently heated and the heat is sufficiently transmitted to the inside of the cylinder to completely melt the resin.

[0005]

By the way, in controlling the heating of the heating cylinder, generally, the density of the heating wire of the heater is locally changed to locally reduce the temperature fluctuation. However, if the heating time is secured so that the resin supplied in front of the screw head is sufficiently melted and the screw head is not locked, the heating of the resin supply part that is in close contact with the water cooling cylinder part (cooling part) equipped in the heating cylinder As a result, the time becomes long, and as a result, there is a problem that the compression portion side, which has a small amount of heat radiation, is excessively heated, and so-called burning occurs in the resin.

An object of the present invention is to provide a heating control device for an injection molding machine in which the screw head is not damaged and the resin is not burnt.

[0007]

According to the present invention, a hopper to which a raw material resin is supplied, a heating cylinder connected to the hopper for melting the raw material resin and storing the molten resin as a molten resin, and a rotating cylinder in the heating cylinder. It is used in an injection molding machine having a screw arranged so that it can move forward and backward, and the heating cylinder is divided into a metering zone zone, a compression zone, and a feeding zone in order from the front end thereof. Heater means for heating the heating cylinder for each of the measuring section zone, the compression section zone, and the supply section zone, and the temperature of the heating cylinder for each of the measuring section zone, the compression section zone, and the supply section zone The measuring part detection temperature, the compression part detection temperature,
And temperature detection means for detecting as a supply portion detection temperature, the measurement portion detection temperature, the compression portion detection temperature, and the supply portion detection temperature and the measurement portion zone, the compression portion zone, and set for each supply portion zone And a control means for controlling the heater means based on the set temperature, and the control means measures the set temperature corresponding to the metering zone, the compression zone, and the supply zone, respectively. The temperature is set as a section setting temperature, a compression section setting temperature, and a supply section setting temperature. When the measuring section detection temperature reaches the measuring section setting temperature, the control means sets the setting temperature of the supplying section zone to the supplying section. It is set to a temperature lower than the preset temperature by a preset temperature, and the preset temperature in the feed zone is set to the preset temperature again after a preset time. Constant, and the heating control device for an injection molding machine is preset time has elapsed after the screw is characterized in that so as to be rotated is obtained.

[0008]

In the present invention, when the detected temperature of the metering zone reaches the set temperature, the set temperature of the supply zone is set lower by a predetermined temperature. Therefore, the predetermined time (cutting prevention time) When the screw is driven to rotate after a lapse of time, the resin does not burn in the supply zone.

[0009]

EXAMPLES The present invention will be described below with reference to examples.

Referring to FIG. 1, the illustrated heating cylinder device includes a heating cylinder 11, and the rear end of the heating cylinder is attached to a water cooling cylinder 12. Further, the nozzle portion 11 is provided at the front end of the heating cylinder 11.
a is formed. The water cooling cylinder 12 is provided with a hopper 13, and the resin is supplied into the heating cylinder 11 from the hopper 13.

A screw 14 is disposed in the heating cylinder so as to be rotatable and movable back and forth. The screw 14 is a screw body portion 14a and a screw head 14b attached to the front end of the screw body portion 14a by a screw portion 141. It has and. As shown in the figure, groove portions 14c are formed on the outer peripheral surface of the screw body portion 14a at a predetermined interval, and the outer peripheral surface between the groove portions 14c is in contact with the inner peripheral surface of the heating cylinder 11 (this portion is Called flight part 14d).

The heating cylinder 11 is divided into a plurality of heating zones. In the example shown in the figure, the nozzle zone 15, the metering zone 16 and the measuring zone 16 are arranged in this order from the front end of the heating cylinder 11.
It is divided into a compression zone 17 and a supply zone 18. A heater 19 is provided on the outer peripheral surface of the heating cylinder 11 corresponding to each heating zone.
The heating cylinder 11 is controlled by controlling the energization of 9
Is controlled. In the illustrated example, one heater 19 is arranged in the metering zone 16 and one heater 19 is arranged in the compression zone 17. Further, two heaters 19 are arranged in the supply zone 18. The heater 20 is also attached to the nozzle zone 15.

A heating cylinder 1 corresponding to each heating zone
1, a thermocouple 21 is attached, and in the illustrated example, a thermocouple 22 is also attached to the rear end of the nozzle portion 11a.

When supplying the resin into the heating cylinder 11, that is, in the measuring step, first, the heater 19 is used.
And 20 are energized to heat the heating cylinder. The temperature of the heating cylinder 11 is detected by thermocouples 19 and 20, and is supplied to a temperature controller (not shown) as a nozzle detection temperature, a metering detection temperature, a compression detection temperature, and a supply detection temperature, respectively. . The temperature adjusting device includes a nozzle zone 15 and a measuring zone 1
6, the set temperature is set for each of the compression zone 17, and the supply zone 18. Here, they are referred to as nozzle set temperature, metering set temperature, compression set temperature, and supply set temperature, respectively. .

In the initial stage of start-up, that is, in the initial stage of the weighing process, the temperature controller compares the set temperature of the measuring unit with the detected temperature of the measuring unit, and when the detected temperature of the measuring unit reaches the set temperature of the measuring unit, it is determined in advance. After a lapse of time (a time sufficient to transfer heat to the inside of the heating cylinder (hereinafter, referred to as cut-off prevention time), for example, 15 minutes), the screw 14 is moved in a direction indicated by a solid arrow by a motor (not shown) or the like. It is ready to rotate.

The resin supplied from the hopper 13 to the heating cylinder 11 by the rotational driving of the screw 14 reaches the compression section zone 17 through the supply section zone 18. In the compression portion zone 17, the groove portion 14c formed in the screw main body portion 14a gradually becomes shallower in depth as shown in the figure, whereby the resin is melted in the compression portion zone 17 and the measurement portion zone is formed. It is accumulated in 16 as a molten resin. Then, the screw 14 is gradually retracted by the molten resin pressure. When the screw 14 is rotationally driven in a state where the resin is not sufficiently melted, the screw 14 cannot be rotated until the above-mentioned breakage prevention time elapses due to the breakage of the screw portion 141. After that, the temperature control device controls ON / OFF of the heater 19 provided in the metering zone 16 based on the metering section set temperature and the metering section detected temperature.

By the way, as described above, the supply zone 18
Is connected to the water-cooled cylinder 12 and there is a resin such as nylon that absorbs heat when it begins to melt. ) Is increased. As a result,
If the heater is simply turned on and off in the supply zone 18 based on the supply set temperature and the supply detected temperature, the temperature at the front side of the supply zone 18 (that is, the portion away from the water cooling cylinder 12) is higher than the supply set temperature. Will also be high. Moreover, as described above, the rotational drive of the screw 14 is stopped until the cut-off prevention time elapses, so that the resin from the hopper 13 is supplied to the supply zone 1.
At the front side of the heating cylinder 11, it becomes attached to the inner wall surface (high-temperature portion) of the heating cylinder 11, where a resin burning nucleus is generated. Although most of the nuclei are scraped off when the screw 14 is driven to rotate, some of the nuclei remain in the form of a film on the inner wall surface.

Generally, at a temperature lower by about 20 to 50 ° C. than the temperature at which the resin starts to burn in about 10 minutes, burning does not occur even if the resin is heated for a long time. Therefore, in the present invention, the compression part set temperature and the supply part set temperature are set until the cut-off prevention time elapses after the nozzle part detected temperature and the metering part detected temperature reach the nozzle part set temperature and the metering part set temperature, respectively. Predetermined temperature (for example, 30
(° C.) set to a low temperature (hereinafter, these set temperatures are referred to as the pre-compression section set temperature and the pre-supply section set temperature). That is,
In the temperature control device, in addition to the compression section setting temperature and the supply section setting temperature, the preliminary compression section setting temperature and the preliminary supply section setting temperature are set, and after starting, the nozzle section detection temperature and the metering section detection temperature are respectively set to the nozzle section set temperature. And when the temperature reaches the metering section set temperature, the temperature controller switches the set temperature to the pre-compression section set temperature and the pre-supply section set temperature, and the compression section zone 17
Also, the temperature of the supply zone 18 is controlled. Then, after the cut-off prevention time has elapsed, the temperature control device sets the compression unit set temperature and the supply unit set temperature again as set temperatures and executes temperature control. In this way, by controlling the heating of the heating cylinder, resin burning can be prevented.

In addition, in the temperature control device, after the compression section detection temperature and the supply section detection temperature reach the compression section set temperature and the supply section set temperature, respectively, a preset time (for example,
If the screw 14 is not rotationally driven even after 5 minutes), an alarm is generated and the preset temperature is switched to the preset compression section set temperature and the preliminary supply section set temperature again to control the temperature of the compression section zone 17 and the supply section zone 18. I do. As a result, the operator is notified of the abnormality and the resin burn is suppressed to the minimum.

After the end of the measuring step, the screw 14 is driven forward as is known, and the molten resin is injected from the heating cylinder 11 into the mold (not shown) through the nozzle portion 11a to perform injection molding. Is executed.

In the above-described embodiment, when the nozzle detection temperature and the metering section detection temperature reach the nozzle section setting temperature and the metering section setting temperature, respectively, the set temperature of the compression section zone and the set temperature of the supply section zone are set to the preset temperatures. Although it is set to be low, the set temperature of the compression zone and the set temperature of the supply zone may be set to be lower by a preset temperature when the detected temperature of the measurement section reaches the set temperature of the measurement section. The set temperature only in the supply zone may be set lower by a preset temperature. In any case, if the temperature detected by the measuring section reaches the setting temperature of the measuring section, the setting temperature of the supply section zone is set lower by a preset temperature, so that the resin burn can be similarly prevented.

Further, even if the heating in the measuring zone (including the nozzle zone) is started earlier than the other zones by a predetermined time, the resin burning can be prevented in the same manner. The heating of other zones (including the nozzle zone) may be interrupted for a predetermined time. Further, in the zones other than the metering zone (including the nozzle zone), the effective value of the electric power supplied to the heater may be reduced by a predetermined amount for a predetermined time.

[0023]

As described above, according to the present invention, when the detected temperature of the measuring section zone reaches the set temperature, the set temperature of the supply section zone is set lower by a predetermined temperature. Since the heating amount of the zones other than the partial zone is set low, when the screw is driven to rotate after the breakage prevention time has elapsed, the resin does not burn in the screw head and the resin burns in the feeding zone. There is an effect that there is no.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of a heating control device for an injection molding machine according to the present invention.

[Explanation of symbols]

 11 Heating Cylinder 12 Water Cooling Cylinder 13 Hopper 14 Screw 15 Nozzle Zone 16 Measuring Zone 17 Compression Zone 18 Supply Zone 19, 20 Heater 21 Thermocouple

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Okamura, Inventor 731-1 Naganumahara-cho, Inage-ku, Chiba-shi, Chiba Sumitomo Heavy Industries, Ltd. Chiba Plant (72) Hiroyoshi Naganuma-cho, Inage-ku, Chiba, Chiba Prefecture 731 Address 1 Sumitomo Heavy Industries, Ltd. Chiba Works

Claims (7)

[Claims] 1. A heating cylinder, which is used in an injection molding machine having a heating cylinder that melts a raw material resin and stores it as a molten resin, and a screw that is rotatably arranged in the heating cylinder so that the heating cylinder can move forward and backward. Is divided into three zones, that is, a metering zone, a compression zone, and a feeding zone, in that order from the front end thereof, and further, heater means for heating the heating cylinder in each of the three zones, and the three zones. Temperature detecting means for detecting the temperature of the heating cylinder as the metering part detection temperature, the compression part detection temperature, and the supply part detection temperature respectively, and the metering part detection temperature, the compression part detection temperature, and the supply part detection temperature. And a control means for controlling the heater means based on the set temperatures set for each of the three zones, and the control means includes The set temperature is set as the metering section set temperature, the compression section set temperature, and the supply section set temperature corresponding to each of the three zones, and the control unit sets the metering section detection temperature to the metering section setting temperature. When the temperature is reached, the set temperature of the supply zone is set to a preliminary supply set temperature which is lower than the supply set temperature by a predetermined temperature, and the set temperature of the supply zone is set after the elapse of a predetermined time. A heating control device for an injection molding machine, wherein the temperature is set again at the supply part set temperature, and the screw is rotationally driven after the lapse of the predetermined time. 2. The heating control device for an injection molding machine according to claim 1, wherein if the screw is not rotationally driven even after a lapse of a predetermined time after the lapse of the predetermined time, the control means outputs an alarm. The heating control device for the injection molding machine is characterized in that the set temperature of the supply zone is set to the set temperature of the preliminary supply section. 3. The heating control device for an injection molding machine according to claim 1, wherein the control means sets the set temperature of the compression section zone to the set temperature when the measured temperature of the measuring section reaches the set temperature of the measuring section. The pre-compression section set temperature lower than the compression section set temperature by a predetermined temperature is set, and the set temperature of the compression section zone is set again to the compression section set temperature after the lapse of the predetermined time. A heating control device for an injection molding machine. 4. The heating control device for an injection molding machine according to claim 3, wherein the control means outputs an alarm if the screw is not rotationally driven even after a lapse of a predetermined time after the lapse of the predetermined time. Of the injection molding machine, wherein the set temperature of the supply section zone is set to the preliminary supply section set temperature and the set temperature of the compression section zone is set to the preliminary compression section set temperature. Heating control device. 5. A heating cylinder, which is used in an injection molding machine having a heating cylinder that melts a raw material resin and stores it as a molten resin, and a screw that is rotatably arranged in the heating cylinder and that can move forward and backward. Is divided into a metering zone, a compression zone, and a feeding zone from the front end thereof in order, and further, heater means for heating the heating cylinder in each of the three zones, and heating in each of the three zones. Temperature detecting means for detecting the temperature of the cylinder as a metering section detection temperature, a compression section detection temperature, and a supply section detection temperature, respectively, the metering section detection temperature, the compression section detection temperature, and the supply section detection temperature, and the three Control means for controlling the heater means based on the set temperature set for each zone, the control means being the heater means. The heating control device for the injection molding machine is characterized in that the heating in the metering zone is started earlier than the other zones by a predetermined amount of time. 6. A heating cylinder, which is used in an injection molding machine having a heating cylinder that melts a raw material resin and stores it as a molten resin, and a screw that is rotatably arranged in the heating cylinder so that the heating cylinder can move forward and backward. Is divided into a metering zone, a compression zone, and a feeding zone from the front end thereof in order, and further, heater means for heating the heating cylinder in each of the three zones, and heating in each of the three zones. Temperature detecting means for detecting the temperature of the cylinder as a metering section detection temperature, a compression section detection temperature, and a supply section detection temperature, respectively, the metering section detection temperature, the compression section detection temperature, and the supply section detection temperature, and the three Control means for controlling the heater means based on a set temperature set for each zone, wherein the control means is the heater means. Is controlled to start heating of the heating cylinder, and then heating of zones other than the metering zone is interrupted for a preset time. 7. A heating cylinder, which is used in an injection molding machine having a heating cylinder that melts a raw material resin and stores it as a molten resin, and a screw that is rotatably arranged in the heating cylinder and can be moved forward and backward. Is divided into a metering zone, a compression zone, and a feeding zone from the front end thereof in order, and further, heater means for heating the heating cylinder in each of the three zones, and heating in each of the three zones. Temperature detecting means for detecting the temperature of the cylinder as a metering section detection temperature, a compression section detection temperature, and a supply section detection temperature, respectively, the metering section detection temperature, the compression section detection temperature, and the supply section detection temperature, and the three Control means for controlling the heater means based on a set temperature set for each zone, wherein the control means is the heater means. After starting the heating of the heating cylinder by controlling the above, the effective value of the AC power supplied to the heater means in a zone other than the metering zone is reduced by a predetermined amount for a predetermined time. A heat control device for injection molding machines.