JPS6365001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic mold temperature regulating device for supplying a heat medium to a mold and thereby controlling the mold temperature during plastic molding.

It has been recognized that it is necessary to optimally control mold temperature depending on the resin material used, product shape, etc., and several types of temperature control devices have been provided.

The one shown in FIG. 1 is called a high temperature maintenance type (60 to 120°C), and water, oil, organic media, etc. are selected as the heat medium depending on the operating temperature. In this type, a heat medium is stored in a tank 1, and a temperature sensor 2 installed inside the tank 1 measures the temperature and sends a signal to a temperature setting device 3. When the temperature is below the set temperature, the temperature inside the tank 1 is The electric heater 4 is energized and heated to raise the temperature to a predetermined temperature. This heated medium is sent to the mold A by the pump 5 and heats the mold A, and when the mold temperature reaches an appropriate temperature, molding begins. When the temperature of the resin is returned to the medium and the temperature rises above the set value, a command is issued to energize the solenoid valve 6, water is passed through the cooling coil 7 provided inside the tank 1, and the medium temperature is cooled down to the desired value. I'm starting to do that. However, since the temperature range of setting device 3 is small,
The drawback was that the heating and cooling processes were repeated unnecessarily. In other words, most models use electric heaters.
At the same time as turning off, the temperature continues to rise by preheating the heater.
The temperature is likely to exceed the set value, and in response to a command from the temperature sensor that detects this, the solenoid valve is immediately opened to allow water to flow through the cooling coil and begin cooling. However, once cooling begins, it tends to cool down to below the set value, and in the end, the heating and cooling steps are repeated unnecessarily, which not only makes it difficult to obtain the desired temperature, but also leads to unnecessary cost increases. It is.

Furthermore, cooling tower water, industrial water, and tap water have been used in cooling coils, but the temperature of the cooling water varies widely, and the cooling rate is easily influenced by nature, which leads to large variations in the heat medium supply temperature. It was appearing as a result.

The device shown in FIG. 2 is called a low temperature maintenance type (40 to 60° C.), so water or an organic medium is selectively used as the heat medium depending on the operating temperature. In this type, the cooling coil 9 of the refrigerator 8 is installed in the tank 10, and when the heat of the resin injected into the mold A is brought into the tank 10 through water or a medium, the temperature inside the tank 10 increases. When the temperature rises, the temperature sensor 11 senses this, and if the temperature is higher than the set temperature of the temperature setting device 12, the refrigerator 8 is started to cool down the temperature until the temperature falls below the set temperature.
Since the amount of heat of the refrigerant in the cooling coil 9 is small, supercooling does not occur in this model.

The above two models are either single-use types that maintain either high temperature or low temperature, which is considered unsatisfactory when it comes to molding high-precision products.

Figure 3 shows tank 1 of the high temperature/low temperature switching type.
Both a heater 14 and a cooling coil 16 of a refrigerator 15 are provided inside the refrigerator 3 . however,
It is impossible to switch between high and low temperatures immediately in order to cut off the effects before switching.
Not only did it slow down the work, but it also caused a huge loss of time.

Therefore, an object of the present invention is to make it possible to supply both a high-temperature medium and a low-temperature medium to a mold independently of each other, and to easily obtain a desired mold temperature over a wide temperature range. In addition, when the high-temperature medium is overheated due to resin heat being brought back, the medium is cooled to a desired temperature value by a cooling medium that is not affected by disturbance elements.
Thus, a stable temperature control effect can be obtained, and if necessary, both a high temperature medium and a low temperature medium can be individually supplied to desired parts of the mold at the same time. We are trying to provide equipment.

Its feature is that it has a high-temperature side medium tank equipped with a heater and a low-temperature side medium tank equipped with a cooling cooler, and the high-temperature medium and low-temperature medium are transported by respective pressure pumps through on-off valves. A medium circulation path is provided in which both media are individually fed into a common supply header and passed through the mold, and returned to each tank individually via an on-off valve from a common return header. A cooling coil is installed to circulate a part of the low temperature medium in the side medium tank, and the temperature sensor installed in each tank is used as the detection end to cool the low temperature medium with the cooling cooler, heat the high temperature medium with the heater, or the cooling coil side. A medium temperature control system is provided to control the circulation of low-temperature medium.

An example of implementation will be explained in detail below.
Figure 4 is an explanatory diagram showing the state of piping to mold A.
7 is a high temperature side medium tank in which a heater 18 is arranged, and 19 is a low temperature side medium tank in which a cooling cooler 20 is arranged. Reference numerals 21 and 22 are pressure pumps that individually feed the high temperature medium and the low temperature medium to the common supply header 23, and are connected to the high temperature side medium tank 17 and the low temperature side medium tank 19, respectively, with piping. 24 and 25 are pressure pumps 2, respectively.
1 and 22, and is provided near the supply header 23. 26 is a return header that commonly receives both of the media that have passed through the mold A;
Reference numerals 7 and 28 designate on-off valves provided near the return header 26 to individually return the heat medium from the return header 26 to the high temperature side medium tank 17 or the low temperature side medium tank 19. Reference numerals 29 and 30 are connection hoses that connect the mold A and the supply header 23 and the mold A and the return header 26, respectively.
Therefore, the heat medium pumped from the high temperature medium side tank 17 or the low temperature side medium tank 19 by the pressure pumps 20, 21 is sent to the common supply header 23 via the on-off valves 24, 25, and passes through the mold A. The on-off valves 27, 2 are connected to the common return header 26.
8, a medium circulation path is formed which returns to each tank individually.

In this embodiment, the supply header 23
Both of the header 26 and the return header 26 have four supply ports and a return port corresponding to the internal pipelines of the mold A, and an on-off valve 31 that can divide the inside into a high-temperature medium path and a low-temperature medium path. , 32.

A cooling coil 33 is installed in the high-temperature medium tank 17, and performs a cooling effect on the high-temperature medium by circulating a portion of the low-temperature medium in the low-temperature medium tank 19. For example, in this embodiment, the pressure pump 2 provided in the medium circulation path on the low temperature side
2 are used together.

34 is a temperature sensor installed in the high temperature side medium tank 17, and 35 is a temperature sensor installed in the low temperature side medium tank 19. 36 is a refrigerator condensing unit installed outside the low-temperature side medium tank 19, which is connected to the cooling cooler 20 installed inside the low-temperature side medium tank 19, and has the function of cooling the cold and hot medium through a refrigeration cycle. I'm going.
Reference numerals 37 and 38 indicate temperature setting machines installed on the control panel B outside the medium tank, which form the main part of the medium temperature control system with the temperature sensors 34 and 35 installed in each tank as the detection ends, and are installed at key points. It gives commands to on-off valves, relays, etc., and controls the cooling of the low-temperature medium by the cooling cooler 20, the heating of the high-temperature medium by the heating heater 18, or the circulation of the low-temperature medium to the cooling coil 33 side.

39 bypasses a part of the low temperature medium pressurized by the pressure pump 22, and inserts the inside of the cooling cooler 20 from the upper part toward the lower part in a double pipe state,
The low temperature side medium tank 19 is opened again at the lower end portion 39a.
This is a bypass path for returning the heat medium to the medium cooling cooler 20, and serves to improve the thermal conductivity of the medium cooling cooler 20 and to stir the heat medium inside the tank. 4
0 is a constant flow valve provided in the middle of the bypass path 39, which returns the low temperature medium to the tank 19 without exceeding a certain amount. This prevents the pressure of the medium from decreasing, thereby making it possible to supply a low-temperature medium that maintains a constant temperature in a steady state. That is, if the low temperature medium is simply returned to the low temperature side medium tank 19 through the bypass path 39 without going through the constant flow valve 40, the flow resistance in this bypass path 39 will be reduced, so a large amount of low temperature medium will be returned to the tank 19. As a result, the pressure of the low-temperature medium that returns to the mold and is supplied to the mold cannot be maintained, and the flow rate supplied to the mold is extremely reduced, and it no longer has the desired cooling effect, so it is not stable at the mold temperature. This arrangement was made in order to obtain a cooling pattern.

41 is a constant flow valve provided in the middle of the pipe line for feeding the low-temperature medium to the cooling coil 33;
By providing this constant flow valve 41, the fluid pressure supplied to the mold A becomes constant, and a stable cooling pattern can be obtained at the mold temperature. Note that 47 is a control opening/closing valve for the low temperature medium. Note that, for example, the pressure pump 22 may not be used for pressure feeding in the bypass path 39 or the above-mentioned pipe line, and a part of the low-temperature medium may be fed to the bypass line or the above-mentioned pipe line by a separate pump or the like.

By the way, as mentioned above, the supply header 23 and the return header 26 each have four supply ports and four return ports, and the mold A is connected to the mold A by the connecting hoses 29 and 30.
In this embodiment, one of the two supply ports or return ports on the high temperature or low temperature medium path side is connected to the internal pipe line on one side of the mold, and the high temperature medium and low temperature medium are connected to each other. Both media are fed into internal conduits on one side and the other side of the mold, and are connected back to each tank. Therefore, when the on-off valves 31 and 32 are in the closed state, a low temperature region or a high temperature region is realized in the mold depending on the supply of heat medium, and a highly accurate heat transfer pattern is created depending on the respective molding conditions. can be obtained. In addition, when starting molding, etc., if you want to flow a high-temperature medium through the entire internal pipe line of the mold to raise the temperature of the mold, open the on-off valves 31 and 32 to feed only the high-temperature medium. On the other hand, when the mold is forcibly cooled, the temperature can be lowered all at once by feeding only the low-temperature medium. Therefore, there is no need to reconnect the connecting hose from the low-temperature side to the high-temperature side each time depending on the usage, and the temperature can be easily and quickly controlled by operating the valve. In this embodiment, each header has four supply ports or four return ports, but the header is not limited to this, and may be formed according to the internal pipe line of the mold. There is no problem with the method of connecting the hoses as long as the direction of flow of the heat medium as described above can be obtained.

Reference numeral 42 denotes a liquid level pipe connected between the lower portions of the high-temperature side medium tank 17 and the low-temperature side medium tank 19, and there is a medium transfer pipe in the middle of which can adjust the movement of the heat medium or the movement of heat to a minimum. A quantity regulating valve 43 is provided.

According to the device of the embodiment, it is possible to supply both the low-temperature and high-temperature media to the mold simultaneously or individually, so that when switching the supply of low-temperature or high-temperature media, the low-temperature medium is transferred to the high-temperature side medium tank 17 or There is a possibility that the high temperature medium will move to the low temperature side medium tank 19, and the on-off valves 24, 25, 27,
28, 31, 32 or an operational error may cause the heat medium to transfer to a different type of medium tank. However, if both tanks are connected through the liquid level pipe 42 as described above, one tank can be transferred. This prevents accidents such as the tank becoming empty or other tanks overflowing and water flowing out of the device. Therefore, not only can loss of the medium be prevented, but also energy loss can be drastically reduced. 4
Reference numeral 4 denotes a liquid level control electrode mounting pipe 44 which is branched and connected near the low temperature side medium tank 19 of the liquid level pipe 42.
and are arranged in parallel in the depth direction of the low temperature side medium tank 19. This makes it possible to easily control the liquid level by using a conductive thread heat medium such as water.
Further, when a non-conductive heat medium is used, an auxiliary tank whose liquid level can be seen directly may be substituted at the mounting position of the electrode mounting pipe 44. Regarding the method of supplying the medium into the tank, if the medium is water, it can be supplied from the water supply port 45 via the water supply on/off valve 46 and by using the water supply channel 47; For example, if the replenishment tank is used as a water supply section, the medium can be supplied to both the high temperature side medium tank 17 and the low temperature side medium tank 19.

48 is an emergency circuit when the refrigerator condensing unit 36 breaks down, and one end is connected to the water supply port 45 via the on-off valve 49.
The other end is connected to the cooling coil 33. In other words, if the unit 36 breaks down, the temperature accuracy will drop until the unit 36 is repaired, but operation is possible only when water is used, and if the temperature of the high-temperature side medium tank 17 rises, the above-mentioned opening/closing By opening the valve 49, the make-up water is changed to cold water, and the water is forced to flow through the cooling coil 33, thereby making it possible to adjust the temperature to a certain extent. If the water temperature in the low-temperature side medium tank 19 is a set temperature higher than the temperature of the supplementary cold water, the temperature can be similarly adjusted by opening the above-mentioned on-off valve 46 and forcibly supplying the water to the low-temperature side medium tank 19.

Next, one method of temperature control using this type of device will be sequentially explained. Note that the heat medium is water.

First, the heat medium is activated by the water supply on-off valve 46 in response to a signal from the electrode rod attached to the liquid level control electrode tube 44 and an instruction from the liquid level control relay provided in the control panel B.
is opened and water is supplied to the medium tank 19 on the low temperature side. The liquid is simultaneously supplied to the high temperature side medium tank 17 through the time equalizing liquid level pipe 42. Each tank 17,1
When 9 reaches a predetermined water storage level, the electrode tube detects its position and sends a signal to the liquid level control relay. As a result, the water supply on/off valve 46 is closed, and the medium replenishment is completed.

Here, a temperature sensor 35 installed in the low-temperature side medium tank 19 detects the temperature of the supplied heat medium, and sends a signal to the temperature setting machine 38, which is a main part of the medium temperature control system. The refrigerator condensing unit 36 is activated through the relay, and the refrigerant is supplied from the unit 36 to the cooling cooler 20 to lower the temperature of the heat medium and make it a desired low-temperature medium. When the low temperature medium reaches a predetermined temperature, the temperature sensor 2
The signal from 0 instructs the temperature setting machine and relay,
The refrigerator condensing unit 36 stops operating and the cryogenic medium is maintained at a predetermined set temperature.

On the other hand, the temperature of the heat medium replenished in the high temperature side medium tank 17 is detected by the temperature sensor 34, and the signal is sent to the temperature setting machine 37 which forms the main part of the medium temperature control system. In this case, the heater 18 is energized through the relay. When the temperature of the heat medium rises and reaches the set temperature, temperature sensor 3
The signal No. 4 instructs the temperature setting machine and relay, the heater is de-energized, and the high-temperature medium is maintained at a predetermined set temperature.

The media at these two types of temperatures are maintained at their respective temperatures through the above-described operations, and when the pressure pumps 21 and 22 are then driven, they are supplied to the respective circuits.

First, the case of supplying a low-temperature medium will be described.

Low-temperature medium pressure pump 2 installed on operation panel B
When switch 2 is turned on, the electromagnetic contactor is energized, the pressure pump 32 is activated, and the low temperature medium is pumped into the mold A. In addition, a portion is sent under pressure to the bypass path 39 and the conduit of the cooling coil 33. In the bypass path, first, the flow passes through the constant flow valve 40, passes through the inside of the cooling cooler 20 for low temperature medium, returns to the low temperature side medium tank 19, and stirs the low temperature medium in the tank. In this case, as described above, since the constant flow valve 40 is provided in the bypass path, the pressure drop with respect to the other circuits is not large.

Next, turn on the low temperature medium valve switch in the operation panel.
, the on-off valves 25 and 28 are each opened, and when the on-off valve 31 in the center of the supply header 23 is closed, the low-temperature medium is passed through a predetermined path from the return header 32 to the low-temperature side medium tank 19 by the hose connection with the mold A. I'm going home.
At this time, waste heat is removed from the product resin in the mold A, and the medium becomes higher in temperature than the previously supplied medium, and returns to the tank 19. Therefore, the temperature of the medium in the tank 19 increases, and the temperature sensor 3
5 is detected and the signal is sent to the temperature setting machine 38. If the temperature becomes higher than the set temperature, the relay is activated and the refrigerator condensing unit 36 is activated to lower the medium temperature. Thereafter, when the set temperature is reached, the refrigerator condensing unit 36 stops operating and maintains the predetermined temperature. At this time, the waste heat received from the mold A is discharged from the medium through the refrigerator condensing unit 36 to the outside of the machine.

Next, turn on the high temperature medium pump switch in the operation panel.
When the on-off valves 24 and 27 are open, and the on-off valves 31 and 32 in the center of the header are closed, the high-temperature medium is forced into a predetermined path by the hose connection between the header and mold A, and the high-temperature medium is sent from the return header 26. tank 17
to return to. At this time, if there is waste heat from the mold A, the temperature becomes higher than the supply medium temperature and returns to the high temperature side medium tank 17. Therefore, the temperature of the medium in the tank increases, and the detected temperature sensor 34 sends a signal to the temperature setting machine. The temperature setting device 37 for high-temperature medium control is equipped with a control mechanism capable of two-step ON/OFF control; the lower position side controls the heater 18, and the higher position side controls the temperature inside the high-temperature side medium tank 17. The supply of low temperature medium to the cooling coil 33 is controlled. Therefore, when the medium temperature rises, if the signal from the temperature sensor 34 exceeds the set temperature on the high temperature side, the low temperature medium control opening/closing valve 47 opens according to the instruction from the temperature setting machine, and the high temperature medium is cooled down to the set temperature. If the on-off valve 47 is closed,
The supply of the low temperature medium to the cooling coil 33 side is stopped and the temperature no longer decreases.

At this time, as mentioned above, since the constant flow valve 40 is provided in the middle of the piping between the on-off valve 47 and the cooling coil 33, a drop in the pressure of the low-temperature medium to the mold A is prevented.

Also, at startup, it is necessary to supply a high temperature body to the entire mold in order to raise the mold temperature, but in this case, first open the on-off valves 31 and 32, turn off the low temperature valve operation switch on the operation panel, and then valve operation switch
When set to the ON position, there is no need to reconnect the hose from the low-temperature medium path to the high-temperature medium path, and high-temperature medium can be supplied to the pipes throughout the mold.

As described above, the present invention has a high-temperature side medium tank equipped with a heater and a low-temperature side medium tank equipped with a cooling cooler, and the high-temperature medium and the low-temperature medium are transported by respective pressure pumps through on-off valves. A medium circulation path is provided in which both media are individually fed into a common supply header and passed through the mold, and returned to each tank individually via an on-off valve from a common return header. A cooling coil is installed to circulate part of the low-temperature medium in the tank, and the temperature sensor installed in each tank is used as the detection end to control the heating of the low-temperature medium by the cooling cooler or the circulation of the low-temperature medium to the cooling coil side. By providing a medium temperature control system, it is possible to supply both the high-temperature medium and the low-temperature medium to the mold independently of each other, and the desired mold temperature can be easily obtained over a wide temperature range. It is something that In other words, it has superior versatility compared to the conventional single-use type, which has an extremely narrow temperature range that can only be maintained at high temperatures or low temperatures. In addition, switching between high and low temperatures is very time-consuming and requires a lot of time.
The heat medium can be switched and supplied more easily and quickly than the low temperature switching type. Furthermore, when the high temperature medium is overheated due to the resin heat being brought back,
This is called a cooling medium that is not influenced by disturbance elements.
That is, it is designed to cool to a predetermined temperature value using a low-temperature medium that maintains a constant temperature, and an extremely stable temperature control effect can be obtained.

Furthermore, in the past, it was thought that the best method was to always keep the temperature of the mold constant, so one or more temperature sensors were attached to the mold, the desired temperature was set with a temperature setting device, and the temperature was adjusted. A control unit that adjusts the flow rate of the hot or cold medium so that the mold reaches the desired temperature, or automatically switches the hot or cold medium as needed when the temperature is higher than the set value, and the hot medium when it is lower than the set value. Units that control mold temperature at a constant temperature have also been commercially available, but with such temperature control devices, it is difficult to manufacture high-precision products in high cycles, which is required as a recent trend. It was hot. That is, in order to satisfy such requirements, attention must be paid to the fact that time is required to change the movement and flow rate of heat or the temperature of the heat medium. As mentioned above, with the method of measuring the mold temperature with a temperature sensor and changing the amount and temperature of the medium, there is no balance between the temperature control time and the molding cycle, and it is impossible to manufacture high-precision products in a high cycle. be. However, in the temperature control device according to the present invention, as is clear from the description of the embodiments, if the supply header and the return header are equipped with on-off valves that can divide the inside into two parts, both the high-temperature medium and the low-temperature medium can be supplied as needed. At the same time, it was also possible to individually supply the desired portions of the mold. In other words, we changed the idea of keeping the mold temperature constant, and instead of keeping the mold temperature at a constant temperature, the temperature of each part of the mold is at various temperatures, and there are low temperature parts and high temperature parts. It is possible to perform wave control of the temperature of various parts in a constant pattern at all times, rather than being constant, and it can be made into a high-performance temperature device that can fully meet recent demands.

Furthermore, in that case, there is no need for a temperature sensor for the mold, which is difficult to install as in the past, and there is no need to use an expensive control unit, making it possible to provide an innovative mold temperature control device. It is something.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the piping state of a conventional mold temperature control device called a high temperature maintenance type;
The figure is an explanatory diagram showing the piping state of a conventional mold temperature control device called a so-called low-temperature maintenance type, and FIG. 3 is an explanatory diagram showing the piping state of a conventional mold temperature control device of the so-called high-temperature/low-temperature switching type. , FIG. 4 is an explanatory diagram showing the state of piping in an embodiment of the mold temperature control device according to the present invention. A... Mold, 17... High temperature side medium tank, 18... Heater, 19... Low temperature side medium tank, 20... Cooling cooler, 21, 22... Pressure pump, 23... Supply header, 24, 25... Open/close valve, 26 ...Feedback header, 27, 28... Opening/closing valve, 31, 32... Opening/closing valve, 33... Cooling coil, 34, 35... Temperature sensor, 40, 41... Constant flow valve.

Claims (1)

[Scope of Claims] 1. It has a high-temperature side medium tank equipped with a heater and a low-temperature side medium tank equipped with a cooling cooler, and the high-temperature medium and low-temperature medium are transferred by respective pressure pumps through on-off valves. A medium circulation path is provided in which both media are individually fed into a common supply header and passed through the mold, and returned individually to each tank from a common return header via an on-off valve. A cooling coil is installed to circulate part of the low-temperature medium in the medium tank, and the temperature sensor installed in each tank is used as the detection end to cool the low-temperature medium with the cooling cooler, heat the high-temperature medium with the heater, or send it to the cooling coil side. A mold temperature control device for plastic molding comprising a medium temperature control system for controlling the circulation of a low-temperature medium. 2. The plastic mold temperature control device according to claim 1, wherein the supply header and the return header each have an on-off valve that can divide the interior into a high-temperature medium path and a low-temperature medium path. 3. The plastic mold temperature control device according to claim 1, wherein a part of the low-temperature medium pumped by the pressure pump is returned to the low-temperature medium tank via a constant flow valve. 4. Claim 1, in which a part of the low-temperature medium pumped by a pressure pump is supplied via a constant flow valve to a cooling coil installed in a high-temperature medium tank, and is returned to a low-temperature medium tank. A mold temperature control device for plastic molding as described in 2. 5. The temperature of the mold for plastic molding according to claim 1, in which the high temperature medium side tank and the low temperature medium side tank are connected at the bottom through a liquid level pipe, and a common medium is used on both the high temperature side and the low temperature side. Regulator.