JPH11235721A - Casting heater, and method for heating/quick-cooling barrel of plastic molding machine using the heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casting heater which can heat/cool the barrel of a plastic molding machine in a short time, and a method for heating/quick-cooling the barrel by using the heater. SOLUTION: Temperature sensors 42 are fitted to the heater and barrel 1 of a plastic molding machine respectively, and the temperatures of the heater and the barrel 1 are monitored separately. Temperature is controlled by using a casting heater 3 equipped with quick-cooling piping 6 for passing a large volume of a cooling medium, temperature controlling piping 7 which passes a small volume of the cooling medium and controls temperature, air piping 8 which discharges the cooling medium in the piping 6 and the piping 7, prevents the deterioration of the medium, and sends air to accelerate the temperature increase of the heater, and change-over valves 10, 11, 12 for changing over the piping of three types. In this way, the problems of the necessity of a long time to adjust the temperature of the barrel to a set value due to overshoot or undershoot can be solved to accomplish the temperature adjustment in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting heater and a method for heating / quenching a barrel of a plastic molding machine using the same.

[0002]

2. Description of the Related Art In an injection molding machine or an extrusion molding machine, when changing from a resin material molded at a high temperature to a resin material molded at a low temperature, molding at a low temperature can be performed unless the set temperature of the barrel is lowered. Therefore, in general, a blower or the like is provided around the barrel, and the barrel is cooled by blowing air to the barrel.

On the other hand, when changing from a resin material molded at a low temperature to a resin material molded at a high temperature, it is necessary to heat the barrel for a long time with a heater provided on the outer periphery of the barrel in order to raise the set temperature of the barrel. Was.

[0004]

However, the heating / cooling has a disadvantage that the barrel has a large mass, and it takes more than one hour especially for a large-sized machine. In order to compensate for these drawbacks, a pipe for introducing gas or liquid and an aluminum cast heater with a sheathed wire heater embedded are provided on the outer periphery of the barrel. In the case where the temperature is set to be high from a low temperature, it is necessary to increase the watt density of the heater to the limit.

However, in this case, too, the mass of the cast heater and the barrel is large, so that the temperature control is extremely difficult.
That is, even when the heater was turned off at the barrel set value at the time of temperature rise, a large overshoot was caused, and at the time of cooling, even if the cooling of the pipe in the heater was stopped at the barrel set value, a large undershoot occurred.

Further, since the temperature of the barrel is detected from the outer peripheral surface of the barrel by a thermocouple at a portion of the inner diameter portion close to the screw,
When the barrel reached the set temperature, the heater was already at a high temperature, causing overshooting and danger of melting the aluminum of the heater.

SUMMARY OF THE INVENTION An object of the present invention is to provide a casting heater and a method for heating and quenching a barrel of a plastic molding machine using the same, which eliminates the above-mentioned drawbacks and can raise and cool the barrel in a short time. Is to do.

[0008]

In order to achieve the above-mentioned object, the present invention relates to a cast heater in which a pipe for introducing gas or liquid and a sheathed wire heater are embedded, and a large-capacity cooling medium is provided at one end of the pipe. A quenching pipe for flowing, a small-capacity cooling medium is allowed to flow, a temperature control pipe for performing temperature control, and a cooling medium in the pipe is discharged to prevent deterioration of the cooling medium and to shorten a heater heating time. An casting pipe heater for a plastic molding machine is provided with an air pipe for sending air and a switching valve for selectively switching the three pipes.

A temperature sensor is provided for each of the heater and the barrel. When the temperature of the barrel rises, the heater is controlled to maintain the same temperature when the temperature rises to a predetermined temperature. When the temperature rise reaches a quenching start temperature lower than a predetermined temperature of the heater,
At the same time as turning off the heater, a cooling medium is introduced from the quenching pipe for an arbitrarily set time, the heater temperature is reduced to a predetermined barrel set temperature, and then the heater is again energized to reduce the barrel temperature to the barrel temperature. A method of heating and quenching a barrel of a plastic molding machine using a casting heater characterized by controlling at a set temperature.

Further, when the temperature of the barrel of the plastic molding machine is changed from a low temperature setting to a high temperature setting, the heater is energized and air is introduced from an air pipe into a pipe of the heater. Heating and quenching method of the plastic molding machine barrel.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a temperature sensor is provided for each of a heater and a barrel, and the temperatures of the heater and the barrel are separately monitored. It takes time for the temperature to reach the barrel set temperature due to overshoot or undershoot. In order to remove the drawback, a rapid cooling pipe through which a large-capacity cooling medium flows, a temperature control pipe through which a small-capacity cooling medium flows, and a temperature control pipe, and a cooling medium in the pipe are discharged to deteriorate the cooling medium. In addition, the temperature control is performed by using an air pipe for sending air for shortening the heater heating time and a cast heater provided with a switching valve for selectively switching the three pipes.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 1 denotes a barrel provided with a temperature sensor 2 for detecting a barrel temperature. Reference numeral 3 denotes an aluminum cast heater in which a pipe for introducing gas or liquid and a sheathed wire heater are embedded, and a temperature sensor 4 for detecting the temperature of the heater itself is provided. At one end of the pipe of the heater 3, a quenching pipe 6 through which a large-capacity cooling medium, for example, oil from a hydraulic source 5 flows,
A temperature control pipe 7 for flowing a small volume of oil and controlling the temperature, and discharging the oil from the pipe to prevent the deterioration of the oil and to remove air from an air source 9 for shortening the heater heating time. An air pipe 8 to be sent is connected, and each pipe 6 to 8
The solenoid-operated directional control valves 10 to 12 provided for the heater 3 are selectively switched so that a large or small capacity cooling medium or air acts on the heater 3.

On the other hand, an oil cooler 1 is provided at the other end of the pipe.
A return circuit 15 is connected to the oil tank 14 via 3. Further, a check valve 16 is provided in the air pipe 8 so that oil from the rapid cooling and temperature control pipes 6 and 7 does not flow backward. The temperature control pipe 7 is provided with a needle valve 17 for adjusting the amount of oil so that the temperature can be finely adjusted.

The operation of the present invention will be described with reference to the time chart of FIG. 3 and the operation state of each function. The temperature curve 20 of the heater rises rapidly with the start of the temperature rise, and the predetermined heater set temperature a Heater 3 turns ON and OFF
Then, it is controlled so as to maintain the same temperature a. On the other hand, when the barrel temperature curve 21 rises more gently than the heater temperature curve 20 and reaches the quenching start temperature b set lower than the heater set temperature a, the power supply to the heater 3 is turned off, and at the same time, no excitation is performed. Electromagnetic switching valves 10 to 12
Electromagnetic switching valve 10 of the quench pipe 6 is excited among the acts only heater 3 T ₁ time set arbitrarily timer oil mass from the hydraulic source 5 is not shown, set up to now Temperature The heater temperature kept at a is rapidly cooled to a barrel set temperature c lower than the heater set temperature a and higher than the rapid cooling start temperature b. When set in the timer time T ₁ is too becomes electromagnetic switching valve 10 is unexcited, the oil of high capacity from temperature control pipe 6 will not act on the heater 3, in order to raise the temperature of the barrel 1 to barrel set temperature c The heater 3 is energized again, and this time, the electromagnetic switching valve 11 of the temperature control pipe 7 is excited,
A small amount of oil acts on the heater 3 via the temperature control pipe 7.

During this time, the barrel temperature curve 21 continues to rise, and when the barrel temperature curve 21 reaches a preset barrel set temperature c, the heater 3
Is stopped, and the temperature is controlled at the barrel setting temperature c.

When the barrel set temperature C is higher than the barrel set temperature c, the pipe in the heater 3 contains oil for rapidly cooling or adjusting the temperature of the heater. By removing the oil, the amount of heating can be reduced by the mass of the oil, and the barrel can be heated up more quickly, so that deterioration of the oil can be prevented. That is, the ON / OFF of the heater 3 and the electromagnetic switching valve 1 of the temperature control pipe 7
1 is repeatedly performed. That is, the electromagnetic switching valves 10 and 11 are de-energized and the electromagnetic switching valve 12 is excited, so that the air from the air source 9 acts on the heater 3 and at the same time, heats up the temperature C which is a higher barrel set temperature. To this end, the heater 3 is energized.

[0017]

As described above, according to the present invention, it takes a long time for the conventional barrel heating / cooling to reach the barrel set temperature due to overshoot or undershoot. Has been removed and the barrel set point can be reached in a short time.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a heater of the present invention and a method for heating and quenching a barrel of a plastic molding machine using the heater.

FIG. 2 is a view showing one embodiment of the present invention, and is a view taken in the direction of arrow Z in FIG. 1;

FIG. 3 is a diagram showing one embodiment of the present invention, and is an explanatory diagram showing time and operating states of respective functions.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Barrel 2 Temperature sensor (for barrel temperature detection) 3 Aluminum cast heater 4 Temperature sensor (for heater temperature detection) 5 Hydraulic source 6 Rapid cooling pipe 7 Temperature control pipe 8 Air pipe 9 Air source 10, 11, 12 Electromagnetic switching valve 13 Oil cooler 14 Oil tank 15 Return circuit 16 Check valve 17 Needle valve 20 Heater temperature curve 21 Barrel temperature curve

Claims (3)

[Claims] 1. A casting heater in which a pipe for introducing a gas or a liquid and a sheathed wire heater are embedded, a rapid cooling pipe for flowing a large-capacity cooling medium at one end of the pipe, and a small-capacity cooling medium for flowing. A temperature control pipe for performing temperature control, an air pipe that discharges a cooling medium in the pipe to prevent deterioration of the cooling medium, and sends air for shortening a heater heating time, and the three pipes are selectively used. A casting heater for a plastic molding machine, comprising a switching valve for switching. 2. A temperature sensor is provided for each of the heater and the barrel. When the temperature of the barrel rises, the heater is controlled to maintain the same temperature when the temperature rises to a predetermined temperature, and then slower than the temperature rise of the heater. When the temperature rise of the barrel reaches the quenching start temperature lower than the predetermined temperature of the heater, the heater is turned off, and at the same time, a cooling medium is introduced from the quenching pipe for an arbitrarily set time to reduce the heater temperature. The heating and quenching of the barrel of the plastic molding machine using the heater according to claim 1, wherein the barrel temperature is controlled at the barrel setting temperature by lowering the temperature to a predetermined barrel setting temperature and then energizing the heater again. Method. 3. When the temperature of the plastic molding machine barrel is changed from a low temperature setting to a high temperature setting, air from an air pipe is introduced into a pipe of the heater as well as energization of the heater. The method of heating and quenching the barrel of the plastic molding machine described.