JP2010099844A - System for controlling temperature of mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system which can control the temperature of a mold over a wide range from a low temperature zone to a high temperature zone by using the waste heat of the mold and cold and hear by a chiller by a simple mechanism. <P>SOLUTION: The system comprises a cooling tank 1 for storing a cooling liquid cooled by a cooling device 5, an adjustment tank 2 for storing the cooling liquid from the cooling tank 1, a cooling liquid circulation channel 11 starting from the adjustment tank 2 to return to the adjustment tank 2 by way of the mold 10, a branch channel 12 which branches in the circulation channel and reaches the cooling tank, a control valve 13 set in the branch channel, and a temperature sensor 15 for detecting the temperature of the cooling liquid in the adjustment tank. When the detected temperature of the temperature sensor 15 is a set temperature or above, the control valve 13 is opened, and part of the cooling liquid of a high temperature in the circulation channel is returned to the cooling tank 1, and the cooling liquid of a low temperature in an amount corresponding to the amount of the cooling liquid returned to the cooling tank is supplied from the cooling tank 1 to the adjustment tank 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a temperature adjustment system for controlling a synthetic resin molding die to a desired set temperature.

Conventionally, in plastic molding, a molten resin injected from a molding machine into a mold is cooled and solidified in the mold, and after sufficiently cooled, taken out of the mold to produce a plastic molded product.
As a means for cooling the mold, a method of circulating the cooling water cooled by the cooling device to the mold is employed. Temperature control is generally performed so that a flow path for passing a cooling liquid is provided inside the mold and the cooling liquid is maintained at a constant temperature so that the mold temperature matches the molding temperature. The mold temperature is generally controlled within a range of 10 ° C. to 30 ° C. according to the heat deformation temperature of the resin to be molded.
However, in the case of a resin having a high thermal deformation temperature, the mold temperature is a room temperature or higher, for example, 40 ° C. to 60 ° C. like EVA resin or ABS resin, and in the case of polycarbonate resin, a high temperature region around 80 ° C. There are cases that you want to keep in. In such a case, the cooling system using only the cooling water circulation circuit as described above cannot cope.

Therefore, as a method for controlling the mold temperature from the low temperature region to the high temperature region, for example, a means for incorporating a heater for raising the temperature of the mold into the mold cooling system as shown in Patent Document 1 has been proposed. There is also known a method of obtaining a coolant having a predetermined temperature by mixing an appropriate amount of a high-temperature coolant separately heated by a heater with a low-temperature coolant.
Japanese Patent Laid-Open No. 5-16198

  The above-described method of raising the temperature using the heater requires a highly accurate temperature control system that balances the cooling device and the heater, which makes the equipment expensive and requires a heater and ancillary equipment to make the system complicated. As a result, the manufacturing cost and running cost are high.

  Therefore, the present invention has been proposed in order to solve the above-described conventional problems, and a desired metal mold can be obtained by using waste heat of a mold and cold heat of a cooler without using a heater. The main object of the present invention is to provide a mold temperature control system capable of adjusting the mold temperature over a wide range from a low temperature range to a high temperature range with a simple mechanism.

In order to achieve the above object, the present invention takes the following technical means. That is, in the temperature control system for a molding die according to the present invention, a cooling tank that stores the cooling liquid cooled by the cooling device, an adjusting tank that stores the cooling liquid from the cooling tank, and an adjusting tank A coolant circulation path returning from the mold to the adjustment tank, a branch path branched from the middle of the circulation path to the cooling tank, a control valve provided in the middle of the branch path, It consists of a temperature sensor that detects the temperature of the coolant in the circulation channel or adjustment tank, and when the detected temperature of the temperature sensor exceeds the set temperature, the control valve opens and a part of the hot coolant in the circulation channel Is formed so that the low-temperature cooling liquid flows into the adjustment tank from the cooling tank by the amount of liquid returned to the cooling tank.

  Since the molding die temperature control system of the present invention is configured as described above, the mold is cooled by circulation of the cooling liquid in the adjustment tank separated from the cooling tank, and the circulating cooling liquid is changed by the mold temperature. When the temperature rises above the set temperature, a part of the high-temperature coolant in the circulation channel is returned to the cooling tank, and the low-temperature coolant flows into the adjustment tank from the cooling tank by the amount of the returned liquid. The circulating coolant can be automatically adjusted to the set temperature, which enables the high-temperature circulating coolant necessary to maintain the mold temperature in the high temperature range to save energy by utilizing the waste heat of the mold. The cooling liquid in the cooling tank separated from the adjustment tank can be maintained at a low temperature, so that the heat load of the cooling device can be reduced and the running cost can be reduced. is there.

(Means and effects for solving other problems)
In the above invention, it is preferable that the cooling tank and the adjustment tank are formed in an integral structure separated by a partition wall.
With this two tank integrated structure, the entire tank can be made compact and the installation space can be reduced.

In the above invention, the liquid level of the cooling tank is arranged to be higher than the liquid level of the adjustment tank, and an overflow port is provided at the upper edge of the cooling tank, and the amount overflowing from the overflow port flows into the adjustment tank. It is good to have a configuration formed as described above.
Accordingly, it is possible to allow the low-temperature cooling liquid to flow from the cooling tank to the adjustment tank by the amount of liquid accurately returned from the circulation flow path to the adjustment tank, and it is possible to easily form a port for the flow-in.

Moreover, in the said invention, it is good to set it as the structure by which the evaporator of the cooling device which cools a cooling fluid is arrange | positioned inside a cooling tank.
As a result, the evaporator is hidden and the appearance image becomes smart, and by forming the evaporator with a screw-type heat exchanger, ice can be attached to the peripheral surface of the screw to store a large amount of cold heat. Compared with the case where the is provided outside the tank, the pipeline and pump for circulating the cooling water to the cooling tank can be omitted, and the configuration can be simplified.

Furthermore, in the present invention, the evaporator of the cooling device may be provided outside the cooling tank, and the cooling liquid cooled by the evaporator may be formed to flow into the cooling tank.
Thereby, there exists a merit which can employ | adopt the plate type heat exchanger which has high heat exchange efficiency for an evaporator.

Hereinafter, a temperature control system for a molding die according to the present invention will be described based on an embodiment shown in the drawings.
FIG. 1 is an explanatory view showing a first embodiment of a temperature control system according to the present invention, and FIG. 2 is a block diagram thereof. Reference numeral 1 denotes a cooling tank for storing the cooling liquid, and FIG. 2 also shows an adjustment tank for storing the cooling liquid. In this embodiment, the cooling tank 1 and the adjustment tank 2 are formed as an integral tank divided by a partition wall 3, and are arranged so that the liquid level of the cooling tank 1 is higher than the liquid level of the adjustment tank, The upper edge of the partition wall of the cooling tank 1 is cut away to form an overflow port 4, and the overflow from the overflow port 4 is provided so as to flow into the adjustment tank 2.

  Reference numeral 5 denotes a cooling device that cools the cooling water. The compressor 6 compresses a refrigerant such as CFC, the condenser 7 that condenses the compressed refrigerant from the compressor, the screw-type evaporator (heat exchanger) 8, and these devices. The evaporator 6 is arranged inside the cooling tank 1 so as to directly cool the cooling water in the cooling tank by heat exchange. In addition, since the cooling device 5 is a general heat pump type cooling device using the evaporation heat of the refrigerant, detailed description thereof is omitted.

  Further, in this temperature control system, a coolant circulation passage 11 returning from the adjustment tank 2 to the adjustment tank 2 through the pump P and the mold 10 of the plastic molding machine, and a flow path to the mold 10 of the circulation path 11 A branch flow path 12 branched from the middle to reach the cooling tank, and a temperature sensor 15 for detecting the temperature of the coolant in the adjustment tank 2 are provided. Further, a control valve 13 is provided in the middle of the branch flow path 12, and a bypass flow path 14 that is distributed from the control valve 13 and returns to the adjustment tank 2 is provided.

In the present embodiment, the control valve 13 functions as a distribution valve between the branch flow path 12 and the bypass flow path 14, and the flow path to the cooling tank 1 of the branch flow path 12 is normally closed, and the bypass flow path 14 When the temperature detected by the temperature sensor 15 in the adjustment tank is equal to or higher than a desired set temperature, the flow path to the cooling tank 1 of the branch flow path 12 is opened, and the circulation flow path is opened. A part of the cooling liquid is returned to the cooling tank 1, and the branch flow path 12 to the cooling tank is set to be closed when the detected temperature falls below the set temperature. The means for controlling such settings can be easily performed by computer control incorporating a program.
The bypass flow path 14 is for returning the coolant in the circulation flow path 11 to the adjustment tank 2 when a trouble occurs in the flow path in the mold 10 for some reason. Is appropriately adjusted by the valve 16, and the valve 16 is closed when no bypass is required. The bypass channel 14 can be omitted from the present system.

  As the cooling liquid used in the present system, an antifreeze liquid in which an antifreeze such as ethylene glycol is mixed in water is used, but any liquid having equivalent physical properties may be used.

  In the above configuration, when the detection set temperature of the coolant circulating through the mold 10 is set to 50 ° C. and driven, the coolant in the adjustment tank 2 is circulated through the circulation channel 11 by the pump P, and the mold 10 is cooled. To do. At this stage, the cooling liquid in the cooling tank 1 is maintained at a low temperature, for example, −20 ° C. by the evaporator 8 of the cooling device 5, and does not flow into the adjustment tank 2.

When the coolant in the adjustment tank 2 recirculated from the circulation channel 11 absorbs the heat of the mold and exceeds 50 ° C., the temperature is detected by the temperature sensor 15 and reaches the cooling tank 1 of the control valve 13 Is opened, and a part of the coolant having a high temperature in the circulation channel 11 is returned to the cooling tank 1. The liquid amount in the cooling tank 1 is increased by the returned liquid amount, the liquid level rises, overflows from the overflow port 4 and flows into the adjustment tank 2, and the liquid temperature in the adjustment tank 2 decreases. When the cooling liquid in the adjustment tank 2 becomes 50 ° C. or lower, the temperature sensor 15 detects the flow path leading to the cooling tank 1 by the control valve 13. By repeating this operation, the temperature of the coolant flowing through the mold 10 can always be automatically adjusted to the set temperature.
Note that the control valve 13 is preferably set so that a small amount of coolant flows instead of being completely closed even when the coolant in the adjustment tank 2 becomes 50 ° C. or lower. Thereby, the rapid temperature rise in the adjustment tank by mold temperature absorption can be suppressed.

  Further, in this embodiment, the screw-type evaporator 8 of the cooling device 5 is arranged inside the cooling tank 1 so as to directly cool the coolant, so that the evaporator 8 is hidden and the appearance image becomes smart, A large amount of cold energy can be stored by attaching ice to the peripheral surface of the screw tube of the evaporator 8, and in addition, as in the case where the evaporator described later is installed outside the cooling tank, cooling water is supplied to the evaporator and the cooling tank. The circulating pipeline and pump can be omitted, and the configuration can be simplified.

  In addition, as shown in FIG. 3, the evaporator 8 is installed outside the cooling tank 1, the evaporator 8 and the cooling tank 1 are connected by the coolant circulation pipeline 17, and the cooling water is circulated by the pump P1. May be. In this case, the cooling water circulation pipeline 17 and the pump P1 are required as compared with the previous embodiment, but there is an advantage that a plate heat exchanger having high heat exchange efficiency can be adopted for the evaporator 8.

In the mold temperature control system of the present invention, the means for introducing the high-temperature cooling water in the circulation channel 11 into the cooling tank 1 is not limited to the above-described embodiment, and various methods are conceivable.
FIG. 4 is a slight modification of the embodiment shown in FIGS. 1 and 2. An electromagnetic opening / closing valve 18 and a control valve 19 interlocking with the electromagnetic opening / closing valve 18 are provided in the middle of the branch flow path 12. Is provided. The electromagnetic on-off valve 18 and the control valve 19 serve the same function as the control valve 13 shown in the previous embodiment, and the control valve 19 is normally closed or narrowed down by the operation of the electromagnetic on-off valve 18. When the detected temperature of the coolant in the adjustment tank 2 by the temperature sensor is equal to or higher than a desired set temperature, the electromagnetic opening / closing valve 18 is operated to open the control valve 19 and a part of the high-temperature coolant in the circulation channel 11 Is returned to the cooling bath 1. When the coolant temperature in the adjustment tank 2 becomes lower than the set temperature, the electromagnetic opening / closing valve 18 is operated and the adjustment valve 19 is closed or set to be narrowed down. Therefore, also in this embodiment, the temperature of the coolant flowing through the mold 10 can always be automatically adjusted to the set temperature as in the previous embodiment. Reference numeral 20 in the drawing indicates a bypass flow path that returns from the coolant circulation flow path 11 to the mold to the adjustment tank 2.

FIG. 5 shows still another embodiment of the means for introducing the high-temperature cooling water into the cooling tank 1. Cooling returning from the adjusting tank 2 to the adjusting tank 2 through the pump P and the mold 10 of the plastic molding machine. A liquid circulation flow path 11 and a branch flow path 12 branched from the middle of the flow path returning from the mold 10 of the circulation flow path 11 to the adjustment tank 2 to reach the cooling tank are provided. As in the example, a control valve 13 that opens and closes according to the temperature detected by the temperature sensor 15 is provided. Reference numeral 21 denotes a bypass flow path that returns from the coolant circulation flow path 11 reaching the mold 10 to the adjustment tank 2.
Therefore, also in this embodiment, the temperature of the coolant flowing through the mold 10 can always be automatically adjusted to the set temperature as in the previous embodiment.

  Moreover, FIG. 6 shows the Example which added the some change to the Example shown in FIG. 5, Comprising: From the adjustment tank 2 to the adjustment tank 2 through the pump P and the metal mold | die 10 of a plastic molding machine. A return coolant circulation channel 11 and a branch channel 12 branched from the middle of the circulation channel 11 returning from the mold 10 to the adjustment tank 2 and reaching the cooling tank 1 are provided. An electromagnetic open / close valve 18 is provided in the middle of the circulation flow path 11 leading to, and a control valve 19 interlocking with the electromagnetic open / close valve 18 is provided in the branch flow path 12 reaching the cooling tank 1. The electromagnetic open / close valve 18 and the control valve 19 serve the same function as the control valve 13 shown in the previous embodiment, and the electromagnetic open / close valve 18 is normally open and the control valve 19 is closed. The high-temperature coolant in the passage 11 is returned to the adjustment tank 2. When the detected temperature of the coolant in the adjustment tank 2 by the temperature sensor becomes equal to or higher than a desired set temperature, the electromagnetic opening / closing valve 18 is operated to open the control valve 19 and a part of the high-temperature coolant in the circulation channel 11 is cooled. Returned to tank 1. When the coolant temperature in the adjustment tank 2 becomes lower than the set temperature, the electromagnetic switching valve 18 is opened, and at the same time, the adjustment valve 19 is closed or set to be narrowed down. Accordingly, in this embodiment as well, the temperature of the coolant flowing through the mold 10 can always be automatically adjusted to the set temperature as in the previous embodiment.

  Although typical embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments. For example, in the above-described embodiment, the temperature sensor 15 that detects the temperature of the adjustment tank 2 and the side cooling liquid in the circulation flow path 11 is installed in the adjustment tank 2, but may be installed in the circulation flow path 11, or It can also be formed by being incorporated in the control valve 13. In addition, the present invention achieves its object and can be appropriately modified and changed without departing from the scope of the claims.

  The present invention can be applied as a mold temperature control system in a plastic injection molding machine.

Explanatory drawing which shows 1st Example of the metal mold | die temperature control system concerning this invention. The block diagram of the said 1st Example. Explanatory drawing which shows another Example of the metal mold | die temperature control system concerning this invention. The block diagram which shows another Example of the metal mold | die temperature control system concerning this invention. The block diagram which shows the further another Example of the metal mold | die temperature control system concerning this invention. The block diagram which shows another Example of the metal mold | die temperature control system concerning this invention.

Explanation of symbols

P Pump 1 Cooling tank 2 Container lid 3 Bulkhead 4 Overflow port 5 Cooling device 8 Evaporator 9 Conveyor lifting mechanism 10 Mold 11 Circulating channel 12 Branching channel 13 Control valve 14 Bypass channel 15 Temperature sensor 18 Electromagnetic switching valve 18
19 Control valve

Claims (6)

A cooling tank that stores the cooling liquid cooled by the cooling device, an adjustment tank that stores the cooling liquid from the cooling tank, a cooling liquid circulation passage that returns from the adjustment tank to the adjustment tank through the mold, and this circulation flow A branch flow path branched from the middle of the path to the cooling tank, a control valve provided in the middle of the branch flow path, and a temperature sensor for detecting the temperature of the coolant in the circulation flow path or the adjustment tank; Consisting of
When the temperature detected by the temperature sensor exceeds the set temperature, the control valve is opened so that a part of the high-temperature coolant in the circulation flow path is returned to the cooling bath, and only the amount of liquid returned to the cooling bath is the cooling bath. A temperature control system for a molding die formed so that a low-temperature coolant flows into the adjustment tank from the bottom.   The temperature control system for a molding die according to claim 1, wherein the cooling tank and the adjustment tank are formed in an integral structure divided by a partition wall.   It is arranged so that the liquid level of the cooling tank is higher than the liquid level of the adjustment tank, and an overflow port is provided at the upper edge of the cooling tank so that the overflow from this overflow port flows into the adjustment tank. The temperature control system of the molding die according to claim 1 or 2.   The temperature control system for a molding die according to any one of claims 1 to 3, wherein a bypass flow path is provided to return to the adjustment tank from the middle of the circulation flow path from the cooling tank to the mold.   The temperature control system for a molding die according to any one of claims 1 to 4, wherein an evaporator of a cooling device for cooling the coolant is disposed inside the cooling tank.   The temperature control of the molding die according to any one of claims 1 to 5, wherein an evaporator of the cooling device is provided outside the cooling tank, and the cooling liquid cooled by the evaporator flows into the cooling tank. system.

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