JPH078525B2 - Temperature controller for injection heating cylinder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for an injection heating cylinder used when a plastic material such as a thermosetting resin or rubber is injection molded.

[0002]

2. Description of the Related Art A temperature control device for an injection molding machine described in Japanese Utility Model Publication No. 46-13564 has a jacket provided at a required portion of an injection heating cylinder, a band heater is mounted on the jacket, and water flowing through the jacket is used. The heating of the injection heating cylinder by the frictional heat in the injection heating cylinder, the shearing heat of the material, etc. is controlled.

In this temperature control device, a hot and cold water circulation circuit is provided between each jacket and the preheating tank, a pump is provided on the outward path, an electromagnetic opening / closing valve and a flow rate adjusting valve are provided on the return path of each jacket, and further on the return path. A cooler is provided.
On the inflow side of the cooling circuit of the cooler, an electromagnetic opening / closing valve operated by a temperature sensor in the tank is provided.

The electric circuit of the electromagnetic valve on the return path and the electric circuit of the band heater are set so as to detect the temperature of the injection heating cylinder and switch alternately, and in the range in which the injection heating cylinder maintains the set temperature, The solenoid on-off valve is in the open state,
Water is being supplied from the preheat tank to the jacket by the pump, but when the heating cylinder temperature falls below the set temperature, the electromagnetic on-off valve closes the return path and stops water circulation due to switching of the electric circuit. On the other hand, the band heater is heated to raise the heating cylinder temperature.

[0005]

The problem of such a conventional temperature control device is that the water flowing in the jacket is lower than the temperature of the injection heating cylinder even if it is preheated, so the flow is stopped and the band is stopped. It takes time to raise the injection heating cylinder to the set temperature by the heater, so the temperature control by switching is naturally limited, and it is difficult to maintain the set temperature unless switching is performed frequently. It is necessary to raise the temperature of the water in the preheat tank.

The problems concerning the temperature control of this conventional device are as follows.
This can be solved by transmitting the heating by the band heater to the injection heating cylinder through the water in the jacket and continuing to flow the amount of water that keeps the jacket temperature constant to the jacket.

However, the amount of water is 0.1 to 1 minute.
It is a very small amount of 0.5 liters, and as is well known, water that is normally used is liable to generate scales, and this scales adheres to jackets and pipes, forming narrow channels. It is extremely difficult to keep water flowing through the jacket through the minute flow path for a long period of time, and it is difficult to actually use it.

The inventors of the present invention, as a result of repeated research on a medium capable of continuously flowing a trace amount in a jacket, have found that a commonly used thermo-oil or the like can sufficiently achieve the object, and the heating by a band heater is performed. Below, we developed a temperature control device for an injection heating cylinder that uses oil as a medium.

Therefore, an object of the present invention is to keep a small amount of oil continuously flowing into the jacket, and to supply a large amount of oil to the jacket by switching when necessary, so that the injection heating cylinder is overheated or the set temperature is changed by material exchange. Another object of the present invention is to provide a temperature control device for an injection heating cylinder having a new configuration that can be changed.

[0010]

According to the features of the present invention according to the above object, a jacket is provided at a required position of an injection heating cylinder, a band heater is mounted on the jacket, and heating by the band heater is injected through oil in the jacket. In a temperature control device for an injection heating cylinder in which heat is transferred to the heating cylinder and the temperature of the heating cylinder is controlled, and a circulation circuit is connected between the jacket and the oil tank in the temperature adjusting device, a pump is provided on the outward path of the circulation circuit. An electromagnetic switching valve equipped with a bypass flow path for oil from the pump and a main flow path that always permits the flow of a small amount of oil is provided on each outward path of each jacket. Each jacket is equipped with a temperature sensor for switching to the roadside, a heat exchange circuit is installed inside the oil tank, and a pump is installed on the inflow side of the heat exchange circuit. In it is provided off valve actuated by the delivery side oil temperature setter connected to the temperature sensor.

[0011]

[Operation] In the above structure, the oil discharged from the oil tank to the outward path of the circulation circuit by the pump flows into the jacket through the passage of the electromagnetic switching valve arranged in the outward path of each jacket. The oil in the jacket is heated by the band heater, and the oil keeps the injection heating cylinder at the set temperature.

The oil leaked from the jacket to the return path is
The oil is returned to the oil tank and cooled to a predetermined temperature by the heat exchange circuit in the tank. Then, it again flows into the jacket by the pump. The supply and stop of the refrigerant in the heat exchange circuit is performed by operating the electromagnetic on-off valve with the oil temperature setting device for the oil discharged from the pump.If the oil temperature is below the set value, the electromagnetic on-off valve closes. Operates to stop the supply of refrigerant.

The flow rate of oil in each jacket varies depending on the flow path of the electromagnetic switching valve in the outward path, and is 0.
Although the flow rate is limited to a minute amount of 1 to 0.5 liters and the temperature of the injection heating cylinder is maintained at the set temperature, a large amount of oil flows into the jacket in the bypass flow path and the temperature of the injection heating cylinder is kept in a short time. To descend. The switching of the flow rate is performed by operating the electromagnetic on-off valve depending on the temperature of the jacket.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference numeral 1 in the drawing is an injection heating cylinder having a screw inside, and a required number of jackets 2 are provided on the outer periphery of the injection heating cylinder separately in a front part, an intermediate part and a rear part. The band heater 3 is attached.

Reference numeral 4 denotes a temperature adjusting device, which includes an oil tank 6 having a heat exchange circuit 5 incorporated therein, and an oil circulation circuit 7 is connected between the oil tank 6 and each jacket 2. A pump 8 for discharging oil is provided on the outward path 7a of the circulation circuit, and a flow rate adjusting valve 9, an electromagnetic opening / closing valve 10, and a flow meter 13 are provided in order on each outward path of each jacket 2.

The electromagnetic switching valve 10 has a bypass flow passage 11 through which a large amount of oil flows and a variable throttle.
It is provided with a main flow path 12 that always allows a small amount of oil to flow. The electromagnetic operating portion of the electromagnetic opening / closing valve 10 is electrically connected to the thermometer 15 of the temperature sensor 14 provided in the jacket 2, and switches the bypass flow passage 11 and the main flow passage 12 by an electric signal from the thermometer 15.

Reference numeral 16 is an electromagnetic on-off valve provided on the inflow side of the heat exchange circuit 5, the electromagnetic operating portion of which is electrically connected to an oil temperature setting device 18 connected to a temperature sensor 17 on the pump discharge side to discharge the pump. When the temperature of the oil on the side is below the set temperature, it closes and stops the supply of the cooling medium.

Reference numeral 19 is an auxiliary tank provided by connecting to the forward path of the front jacket 2 and the return path 7b of the circulation circuit 7,
Reference numeral 0 is a pressure adjusting valve provided over the forward path 7a and the return path 7b on the pump discharge side, 21 is an air vent cock of the entire circuit provided in the auxiliary tank circuit 22, and 23 is a stop valve of the heat exchange circuit 5.

When the thermosetting resin is molded, the injection heating cylinder 1 is set to a high temperature on the front side and a low temperature on the rear side. Therefore, in the temperature control device having the above configuration, the flow rate adjusting valve 9 adjusts the flow rate of oil in each outward path to individually set the temperature of the jacket.

In addition, at the time of the first circulation of the oil in the molding preparation stage, the electromagnetic switching valve 10 is set on the bypass flow passage 11 side, so that the oil from the pump 8 has a constant pressure (5 / cm ² ). In a short time, the jacket 2 is filled, and a part of the oil commensurate with the amount of inflow flows back from the return path 7b to the oil tank.

After the heating by the jacket 2 is started, the electromagnetic switching valve 10 is switched to the main flow path 12 side, and the flow rate of oil to each jacket 2 is limited to a very small amount by the throttles provided therein.

The oil flowing into each jacket 2 suppresses the temperature rise of the oil in the jacket heated by the band heater, and also suppresses the rise of the heating cylinder temperature due to the frictional heat and the shear heat generation in the injection heating cylinder to suppress the injection heating. The temperature of the cylinder 1 is maintained at the set temperature.

The oil flowing out from the jacket 2 to the return path 7b due to the inflow of oil has a higher oil temperature than that at the time of inflow, and is returned to the oil tank 6 as it is, and the heat exchange circuit 5 in the tank causes the oil to reach a predetermined temperature. (30 ° -80 ° C)
Is cooled down. Then, the water flows to each jacket 2 again by the pump 8.

When the temperature of the oil detected by the temperature sensor 17 is lower than the set temperature, the oil temperature setting device 18 closes the electromagnetic on-off valve 16 to temporarily shut off the inflow side of the heat exchange circuit 5 for cooling. The supply of medium is stopped. And the temperature in the tank rises due to the temperature of the recirculated oil itself,
When the detected temperature reaches the set temperature, the oil temperature setter 18 opens the electromagnetic opening / closing valve 16 to supply the cooling medium.

The temperature of the injection heating cylinder 1 cannot be controlled by the inflow of a small amount of oil, and when the temperature rises, the thermometer 15
In response to a command from the electromagnetic on-off valve 10, the bypass flow passage 11
And a large amount of oil flows into the jacket 2. As a result, the temperature of the injection heating cylinder 1 drops in a short time. This state is maintained until the heating cylinder temperature reaches the set temperature, and the electromagnetic on-off valve 10 switches to the main flow path 12 again and keeps the set temperature. Such a switching operation can be performed for each jacket, and the temperature of each part of the injection heating cylinder 1 is controlled accordingly.

[0026]

As described above, according to the present invention, the electromagnetic switching valve having the bypass passage for the oil from the pump and the main passage for permitting the flow of a small amount of oil at all times is arranged in each forward path of each jacket. , Each jacket is equipped with a temperature sensor that switches the electromagnetic switching valve between the main flow path side and the bypass flow path side, a heat exchange circuit is internally installed in the oil tank, and the temperature sensor on the pump discharge side is connected to the inflow side of the heat exchange circuit. Since the electromagnetic on-off valve that is operated by the oil temperature setting device is provided, the following effects are achieved.

Since the temperature of the injection heating cylinder can be controlled by constantly flowing a small amount of oil to the jacket heated by the band heater, the vertical movement of the heating cylinder temperature is extremely small and the temperature can be kept constant for a long time. it can.

Since the main flow path can be switched to the bypass flow path to allow a large amount of oil to flow in, even if the heating cylinder temperature suddenly changes to the set temperature or higher, the oil flow rate is correspondingly increased and the heating cylinder temperature is changed. The set temperature can be lowered in a short time.

Since the heated oil in the jacket is cooled and circulated and used, there is no obstacle due to water stains when water is used as a medium, and deterioration due to heating is extremely small. Therefore, a fixed amount of a small amount of oil is supplied. Can be continued for a long time, and even if it is used for a long time, there is almost no need to replace the medium.

Since it is easy to maintain the oil temperature, pressure, flow rate, etc. constant, it is possible to improve temperature accuracy, and it is possible to suppress an increase in the heating cylinder temperature due to frictional heat or shear heat generation in the injection heating cylinder. Stable injection molding can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a temperature control device for an injection heating cylinder according to the present invention.

[Explanation of symbols]

 1 Injection Heating Tube 2 Jacket 3 Band Heater 4 Temperature Control Device 5 Heat Exchange Circuit 6 Oil Tank 7 Circulation Circuit 8 Pump 9 Flow Control Valve 10 Electromagnetic Switching Valve 11 Bypass Flow Path 12 Main Flow Path 14 Temperature Sensor 15 Thermometer 16 Electromagnetic Open / Close Valve 17 Temperature sensor 18 Oil temperature setting device

Claims (1)

[Claims] 1. A jacket is provided at a required position of the injection heating cylinder, and a band heater is attached on the jacket, and the heating by the band heater is transferred to the injection heating cylinder through oil in the jacket and the heating cylinder temperature is controlled. In the temperature control device of the injection heating cylinder in which a circulation circuit is connected across the jacket and the oil tank in the temperature control device, a pump is provided in the outward path of the circulation circuit, while the oil from the pump is provided in each outward path of each jacket. An electromagnetic switching valve having a bypass flow passage and a main flow passage that always permits the flow of a small amount of oil is provided, and each jacket is provided with a temperature sensor that switches between the main flow passage side and the bypass flow passage side. A heat exchange circuit is installed inside the oil tank, and an oil temperature setting device connected to the temperature sensor on the pump discharge side is installed on the inflow side of the heat exchange circuit. A temperature control device for an injection heating cylinder, which is provided with a moving electromagnetic on-off valve.