JPH1015944A - Apparatus for heating and cooing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use water with temp. of 100 deg.C or higher as a heating medium to pressurize a high temp. water system and a low temp. water system by a pressure pump or gas pressure. SOLUTION: A mold wherein a plurality of a heating medium passages 63 are provided in a close vicinity to the wall surface of a cavity and connected in parallel and series is used and at least a high temp. water system II circulating high temp. water and a low temp. water system I circulating low temp. water are set to constitutional elements and pressure equal to or higher than the saturation pressure corresponding to the temp. of the circulating water of the high temp. water system is applied to the high and low temp. water systems II, I to make it possible to change over the circulation route wherein the passage 63 of the mold 36 is incorporated in a part of the high temp. water system II and the circulation route wherein the passage 63 of the mold 36 is incorporated in the low temp. water system I.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology of a heating and cooling device for a mold used for molding such as plastic molding.

[0002]

2. Description of the Related Art Injection molding of plastics is performed by injecting molten plastic into a mold having a cavity having the same shape as a desired product shape, and cooling and solidifying the molten plastic. The appearance of the resulting product is, of course, approximately equal to the mold cavity, but strictly different.

In particular, fine irregularities on the cavity surface are often not accurately transferred. This is because the molten plastic is cooled as soon as it comes into contact with the cavity surface, and a thin solidified layer is formed on the surface of the molten plastic, which hinders accurate transfer of fine irregularities on the cavity surface.
The ratio of the size of the fine irregularities on the cavity surface to the size of the fine irregularities on the surface of the obtained plastic molded product is called the transfer rate. In precision plastic injection molding, the transfer rate must be increased. Is one of the issues.

[0004] In plastic injection molding, defective products include "weld", "hike", and "silver".
There are three major defective items, and reducing or eliminating these three major defects is extremely important in the field of the injection process.

The above-described method for improving the transfer rate, and
A molding method called high-temperature molding is known as a measure for reducing large defects. This delays the formation of a solidified layer on the surface of the molten plastic by raising the temperature of the cavity surface in advance, accurately transfers the fine irregularities on the cavity surface, and then cools the mold to completely solidify the plastic molded product It is a method of taking out. By using this high-temperature molding, the above-mentioned three major defects of molding can also be reduced or eliminated. Thus, the high-temperature molding method is an excellent method for injection molding.

However, in high-temperature molding, since it generally takes time to raise and cool the temperature of the mold, it has a disadvantage that the molding cannot be performed within a normal injection molding cycle time and the molding cost is increased.

For example, as a typical example of high-temperature molding, there is a method of embedding an electric heater in a mold for heating the mold. In this method, in order to raise the mold wall temperature, the portion in which the electric heater is embedded must also be heated, so that the heat capacity of the heated portion increases, and it takes a long time to heat to a predetermined temperature, and cooling Time will be extended. The time required for heating and cooling varies greatly depending on the size of the mold, the use environment, and the like. For example, when the mold wall temperature is to be raised or lowered by 50 ° C., such a method in which the electric heater is embedded is It usually took several minutes to several tens of minutes. Naturally, this is unacceptable for molding sites seeking to reduce molding time by competing for several seconds.

A method has been proposed in which an appropriate flow path is provided in a mold instead of an electric heater, and a high-temperature heat medium is passed through this flow path. For example, Japanese Patent Application Laid-Open Nos. 62-117716 and 1
-115606.

One of the advantages of this method is that the heating time can be shortened by providing the flow path close to the mold wall. This is because, in addition to improving the heat conduction between the flow path and the mold wall surface, the heat capacity of the heated portion can be reduced. Another great advantage of this method is that a high-temperature heat medium flows through the flow path during heating and a low-temperature heat medium flows during cooling, so that not only the heating time but also the cooling time can be reduced.

In a high-temperature molding method using a heat medium, a high-temperature heat medium and a low-temperature heat medium are prepared, and a high-temperature heat medium and a low-temperature heat medium are supplied to a mold in accordance with a molding cycle. Switching device is required. Examples thereof are disclosed in JP-A-51-5362 and JP-B-1-26848.

The technique disclosed in Japanese Patent Laid-Open No. 51-5362 will be described with reference to FIG.
1 is a movable mold body, 2 is a fixed mold body, 3 is a movable mold plate, 4
Is a fixed-side template. The movable mold plate 3 and the fixed mold plate 4 are closed to form the cavity 6. Further, between the movable mold plate 3 and the movable mold body 1 and between the fixed mold plate 4 and the fixed mold body 2.
The heat medium passages 7 and 8 are formed between them. Inflow ports 9 and 10 and outflow ports 11 and 12 are formed in these heat medium passages.
The outlets 11 and 12 are connected to a heating medium heating / supplying device 14 and a heating medium cooling / supplying device 15 via a switching valve 16, respectively.

In the above construction, first, as shown in the figure, the switching valves 13 and 16 are connected to the heating medium heating / supplying device 14 to allow the high-temperature heating medium to flow through the passages 7 and 8 so that the inside of the cavity 6 passes through the mold plates 3 and 4. Heat to a predetermined temperature. After the cavity 6 reaches a predetermined temperature, the resin is injected into the cavity 6 from the injection nozzle through the injection port 5 (not shown).
Fill. After the injection of the resin, the switching valves 13 and 16 are switched to the heat medium cooling / supplying device 15 so that a low-temperature heat medium flows through the passages 7 and 8 to cool the resin in the cavity 6. After the resin in the cavity 6 is cooled and solidified, the movable mold body 1 and the fixed mold body 2 are opened to take out a molded product.

By the way, in order to exhibit the effect of high-temperature molding, it is necessary to keep the temperature of the mold wall surface before resin injection near the glass transition point of the resin, preferably at or above the glass transition point. Although the glass transition point of the resin varies depending on the type of the resin, it is generally 100 ° C. to 120 ° C. or higher. Further, the temperature of the mold wall surface during cooling is usually 40 ° C. to 80 ° C., so that the temperature rising temperature range and the cooling temperature range are 40 ° C. to 80 ° C. On the other hand, in order to prevent the molding cycle from being extended, the time allotted for heating and cooling must be limited to 40 seconds at the maximum, and preferably several seconds.

Therefore, the heating rate and the cooling rate are 1
As a specific means for obtaining such a large heating rate / cooling rate, a flow path is provided near the mold wall, and a high-temperature or low-temperature heat medium is provided in this flow path. A method of flowing was proposed. Further, the temperature of the high-temperature heat medium must be at least 100 ° C. to 120 ° C. or higher as described above, and the temperature of the low-temperature heat medium is 40 ° C.
℃-80 ℃ or less.

Although the type of the heat medium is not described in the above-mentioned Japanese Patent Application Laid-Open No. 51-5362, if a heat medium such as oil is used as the heat medium, the oil generally has a high saturation temperature at atmospheric pressure. Therefore, the heat medium on the high temperature side and the heat medium on the low temperature side can be used under the same atmospheric pressure, and even in the above case, the heat medium at the high temperature and the low temperature can be switched. However, if the temperature of the mold wall surface is to be rapidly increased, it is inconvenient to use an oil-based heat medium. This is because the oil-based heat medium has a high viscosity, so the value of the heat transfer coefficient (film coefficient) between the wall of the flow path and the heat medium becomes small, and as a result, the heat transfer to the cavity wall is reduced. There is a problem that it is difficult to obtain a sufficient heating rate and cooling rate. For example, diameter 10
The number of heat transfer systems when an oil-based heat medium of 100 ° C. is flowed at 10 liters / minute through the flow path of mm is estimated to be about 1200 W / ° C./square meter.

However, heat transfer in the case where water is used as a heat medium instead of an oil-based heat medium and water of the same temperature (100 ° C.) and the same flow rate (10 l / min) flows through a flow path of the same diameter of 10 mm. The coefficient is estimated to be 15000 W / ° C./square meter. As described above, when the oil-based heat medium and the water-based heat medium are compared, the heat transfer coefficient of water shows a much larger value than the oil-based heat medium under the same conditions. In fact, the results of our experiments and examinations also revealed that water with a large heat transfer coefficient must be used as the heating medium in order to obtain a rapid temperature rise and cooling rate temperature on the mold wall.

However, when water is used as the heat medium, the temperature of the low-temperature water for cooling the mold wall surface is often 100 ° C. or less, so that pressurization is not necessarily required. In order to maintain the temperature at 100 ° C. or higher, it is necessary to increase the pressure to atmospheric pressure or higher. Therefore, the method disclosed in Japanese Patent Application Laid-Open No. 51-5362, in which the pressure applied to the heat medium is not taken into consideration, is insufficient for switching between high-temperature water and low-temperature water.

[0018]

As described above, the heating and cooling of the mold with the heat medium is an effective method for rapidly increasing and cooling the mold wall temperature. However, when the heating rate and the cooling rate are further increased. Means that the temperature of the heating medium is as high as possible,
And heat transfer coefficient (film coefficient) between heat medium and flow channel wall
Had to be enlarged. If the temperature of the high-temperature heat medium used for heating is to be set to 100 ° C. or higher, an oil-based heat medium whose saturation temperature is 100 ° C. or higher must be used at atmospheric pressure. There was a problem that the value of the coefficient was extremely small, and the mold wall surface temperature was invincible to rapid rise and rapid cooling.

Although it is necessary to use water as a heat medium for the rapid rise and rapid cooling of the mold wall surface temperature, it is necessary to pressurize the water as a heat medium at 100 ° C. or higher, as is well known.

However, in the conventional heating medium / heating / cooling apparatus on the premise of an oil-based heating medium, no consideration is given to pressurization of the heating medium. In other words, since no consideration is given to the pressure difference when switching between the high-temperature heat medium used for heating and the low-temperature heat medium used for cooling, there is a problem that it cannot be used for a heating / cooling system using water as a heat medium. Was.

[0021]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a method in which high-temperature water flows from a high-temperature water system into a heat medium flow passage provided near a cavity wall surface of a molding die. When heating the cavity wall surface, and when cooling and cooling the cavity by flowing low-temperature water from the low-temperature water system into the heat medium flow path, the high-temperature water and low-temperature water are pressurized to the same pressure, and the temperature of the high-temperature water is increased. Is applied to a pressure equal to or higher than the saturation pressure. As a result, high-temperature water of 100 ° C. or more can be used as a heat medium, and the temperature rise rate of the cavity wall surface can be increased accordingly. Further, since the high-temperature water system and the low-temperature water system are maintained at the same pressure, the heat medium used for heating and cooling can be rapidly switched.

Further, since pressurized water is used as a heat medium for heating and cooling the cavity wall surface, the heat transfer coefficient between the heat medium and the flow path wall surface is increased, so that not only the rising speed of the cavity wall surface temperature but also the cooling speed can be increased. In combination with the increase in the temperature of the high-temperature water and the rapid switching of the heat medium, the effect of improving the quality of molded products by high-temperature molding and reducing defective products can be obtained while preventing the molding cycle time from being prolonged. be able to.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION A heating and cooling device for a mold according to the present invention uses a mold in which a flow path of a heat medium is provided close to a wall surface of a cavity, and circulates a high-temperature water system for circulating high-temperature water and low-temperature water. At least a saturation pressure corresponding to the circulating water temperature of the high-temperature water system and applying the same pressure to the high-temperature water system and the low-temperature water system, and causing the flow path of the mold to pass through the high-temperature water system. And a high-temperature circulation path to be incorporated into a part of the low-temperature water system and a low-temperature circulation path to be incorporated into a part of the low-temperature water system.

The heating and cooling device for a mold according to the present invention includes:
A pressurizing pump for discharging a pressure equal to or higher than the saturation pressure corresponding to the circulating water temperature of the high-temperature water system is provided, and the same pressure is applied to the high-temperature water system and the low-temperature water system by the discharge pressure of the pressurizing pump. .

Further, as another means for applying pressure to the high-temperature water system and the low-temperature water system, a pressurized tank containing a pressurized gas and water is provided, and the pressurized tank is connected to the high-temperature water system and the low-temperature water system. A method of performing this is also possible, and is preferable depending on the application.

Further, in the heating and cooling device for a mold according to the present invention, a hot water system for circulating high-temperature water and a low-temperature water system for circulating low-temperature water are at least constituent elements. And a heating water system that circulates heating water at a temperature higher than the high temperature water. The high temperature water system, the low temperature water system, and the heating water system circulate water by means of circulation pumps provided therein, respectively. The heating water system is communicated, and a gas pressure higher than the saturation pressure corresponding to the circulating water temperature of the heating water system is applied to the vicinity of the suction port of the circulation pump of the heating water system to pressurize the high temperature water system and the low temperature water system, It is possible to switch between a high-temperature circulation path in which the flow path of the molding die is incorporated in a part of the high-temperature water system and a low-temperature circulation path in which the flow path of the molding die is incorporated in a part of the low-temperature water system.

The heating water system is provided with at least a heating water circulation pump, a heater and a three-way control valve, and discharge water from the heating water circulation pump flows into an inlet of the three-way control valve through a heater. One of the outlets of the three-way control valve is connected to the suction port of the heated water circulation pump, and the other one of the three-way control valve is connected to the suction port of the high-temperature water circulation pump, and the suction port of the high-temperature water circulation pump is connected. And the suction port of the heated water circulation pump communicates with the hot water system by mixing the heated water system with the hot water system by opening the three-way control valve, thereby enabling temperature control of the hot water system.

Further, the low-temperature water system includes at least a low-temperature water circulation pump, a cooler, and a three-way control valve, and controls a path of water discharged from the low-temperature water circulation pump through the flow path of a molding die. A path is provided that communicates with the inlet of the valve and directly communicates the discharge side of the low-temperature water circulation pump with the inlet of the three-way control valve. One outlet of the three-way control valve is connected to the suction port of the low-temperature water circulation pump. The other outlet is connected to the suction port of the low-temperature water circulation pump through the temperature control tank,
The temperature of the low-temperature water system can be controlled by mixing the water that has passed through the temperature control tank and the water that has not passed through the temperature control tank according to the degree of opening of the three-way control valve.

[0029]

【Example】

(Embodiment 1) FIG. 1 is a block diagram of a heating and cooling apparatus for a molding die as one embodiment of the present invention, and FIGS. 2 to 5 are moldings when the heating and cooling apparatus for a molding die of the present invention is applied to injection molding. It is explanatory drawing of the structure of a type | mold. FIG. 6 is an example of a response measurement diagram of the mold wall surface temperature.

First, the structure of the mold when the heating and cooling device of the present invention is applied to injection molding will be described with reference to FIG. FIG. 3 is a cross-sectional view taken along the line MM of FIG. 2, and FIG. 4 is an enlarged view of a circle N.

In FIG. 2, 56 is a fixed type, 57 is a movable type, 58 is a mold mounting plate, 59 is a locate ring, 60 is a sprue hole, and 61 is an ejector pin. Fixed type 56
The space formed by closing the movable mold 57 is the cavity 6.
2. The fixed mold 56 is positioned at a predetermined position of the injection molding machine by the locate ring 59. The molten resin is injected from an injection nozzle (not shown) into the cavity 62 via the sprue hole 60. As shown in FIG. 2, a number of flow paths 63 are provided along the cavity 62 of the fixed mold 56. The flow path 63 will be described. As shown in FIG. 3, tanks 64A and 64B are provided before and after the fixed mold 56. The flow path 63 is connected to the tanks 64A and 64B by connecting pipes 65A and 65B.
B. The tanks 64A and 64B are connected to a heating and cooling device by supply pipes 66A and 66B.

The plugs 67A, 67B are connected to the supply pipes 66A, 6A.
6B is fixed to the fixed mold 56. The plugs 67A and 67B are provided with thermocouples so that the temperature of the circulating water flowing into and circulating in the flow passage 63 can be detected. As described above, the mold used in the present invention has a structure in which the temperature of the mold wall surface of the cavity 62 can be rapidly increased by arranging a large number of heat medium channels 63 along the cavity 62.

The above-described apparatus for supplying a high-temperature heat medium or a low-temperature heat medium to the flow path 63 of the heat medium of the molding die is the heating / cooling apparatus of the present invention described below.

Next, the heating / cooling apparatus of the present invention will be described with reference to FIG. In FIG. 1, reference numeral 36 denotes a mold described with reference to FIG. 2, I denotes a low-temperature water system, and II denotes a high-temperature water system.

In FIG. 1, the low-temperature water system I has a suction side communicating with a water source 37, and a low-temperature pressurizing pump 17 in which a low-temperature pressure adjusting valve (A) 21 is inserted in parallel. 22, the low-temperature circulation pump 19, the temperature adjusting tank 38, and the low-temperature switching valve (B) 31 communicate with the supply pipe 66A. The supply pipe 66A communicates with the flow path 63, and further with the supply pipe 6
It communicates with the branch point 81 via 6B. The branch point 81 further communicates with the low-temperature switching valve (B) 31 via the low-temperature circulating pump 19 and the low-temperature switching valve (A) 30 via a low-temperature return path 99. 25
Is a suction pressure gauge of the low-temperature circulation pump 19, and 27 is a discharge pressure gauge.

The high-temperature water system II has a suction side communicating with a water source 37, and a high-temperature pressurizing pump 18 having a high-temperature pressure adjusting valve (A) 23 inserted in parallel.
The high temperature circulation pump 20, the heater 29, and the high temperature switching valve (B) 34 communicate with the supply pipe 66A. The supply pipe 66B communicates with the high-temperature switching valve (B) 34 via the branch point 81 via the high-temperature return path 100 via the suction side of the high-temperature circulation pump 20 and the high-temperature switching valve (A) 33. 26 is a suction pressure gauge of the high-temperature circulation pump 20, and 28 is a discharge pressure gauge.

First, the preparation state will be described. The high-temperature pressurizing pump 18 is operated to control the high-temperature pressure regulating valve (A) 23 and the high-temperature pressure regulating valve (B) 24 to
Is set to a value equal to or higher than the saturation pressure (for example, the saturation pressure at 130 ° C. = 2.7 at) corresponding to the target temperature of the high-temperature water (for example, 130 ° C.). If the opening degree of the high-temperature pressure control valve (A) 23 is increased and the opening degree of the high-temperature pressure control valve (B) 24 is reduced, the return amount of the discharge water from the high-temperature pressurizing pump 18 increases. A relationship is used in which the pressure indication value of the total 26 decreases and the pressure indication value increases when the operation is reversed. Thus, the high-temperature water system II is brought into an operating state in which pressurized water corresponding to a target temperature can be circulated as circulating water. The same operation is performed for the low-temperature water system I, and the suction pressure gauge 2 of the low-temperature circulation pump 19 is used.
5 is changed to the suction pressure gauge 26 of the high-temperature circulation pump 20 described above.
Is adjusted so as to show the same value as above, and the operation state is set.

Next, the standby state will be described. Close the low temperature switching valve (B) 31 and the high temperature switching valve (B) 34,
Low temperature switching valve (A) 30, high temperature switching valve (A) 33
Is opened and the low-temperature circulation pump 19 and the high-temperature circulation pump 20 are operated. In this standby state, the temperature of the water discharged from the low-temperature circulating pump 19 is adjusted through a temperature adjusting tank 38, and then the low-temperature circulating pump 19 is passed through a low-temperature switching valve (A) 30.
Return to the suction port and gradually lower the temperature.

The temperature adjustment in the temperature adjustment tank 38 is usually performed mainly by a cooling operation. However, the temperature of the low-temperature water system I may be lower than a necessary temperature depending on molding conditions. In some cases. Even in the case where the temperature of the low-temperature water system I is to be lowered, a part of the circulating water of the low-temperature water system I that has become higher than a predetermined temperature is discharged to the outside without necessarily performing the cooling operation in the temperature adjustment tank 38. The amount of circulating water is replenished from the water source 37 by the low-temperature pressurizing pump 17, so that the water of the water source having a temperature lower than the predetermined temperature is mixed with the circulating water of the low-temperature water system I having a temperature higher than the predetermined temperature to adjust the temperature. Is also possible.

The water discharged from the high-temperature circulating pump 20 is heated by a heater 29, and then heated at a high-temperature switching valve (A).
After returning to the suction port of the high-temperature circulation pump 20 via 33, the temperature is gradually increased.

In the above standby state, after the temperature of the high-temperature water system II reaches a predetermined value, in order to heat the mold 36, the low-temperature switching valve (B) 31 is closed and the low-temperature switching valve (A) 3
In the open state, the high-temperature switching valve (A) 33 is closed, and the high-temperature switching valve (B) 34 is opened, so that high-temperature water pressurized in a predetermined manner flows through the flow path 63 of the mold 36.

As will be described later, high-temperature water flows through the channel 63 of the mold 36.
When the mold wall temperature of the cavity 62 rises rapidly, the molten resin is injected into the cavity 62 through the sprue 60 when the mold wall temperature reaches a predetermined temperature.
After the end of the injection, the cooling of the mold is started when a predetermined time has elapsed.

To cool the mold 36, the high temperature switching valve (A) 33 is opened, the high temperature switching valve (B) 34 is closed, and the high temperature water system II is returned to the standby state. By closing and opening the low-temperature switching valve (B) 31, low-temperature water flows through the flow path 63 of the mold 36.

When the mold 36 is cooled to a predetermined temperature, the movable mold 56 and the fixed mold 57 are opened to take out the molded product.

As described above, in the heating / cooling apparatus shown in FIG. 1, since the high-temperature water system II and the low-temperature water system I are under the same pressure, it is possible to switch freely.

The mold 36 described in FIG. 3 was used as the mold 36, and the response of the mold wall temperature when switching between low-temperature water and high-temperature water was measured using the heating and cooling device described in FIG.

FIG. 6 shows the results. The vertical axis represents the temperature and the horizontal axis represents the time. Since the data obtained by automatically recording the measurement results are used as they are, the time elapses toward the left.

In this case, the temperature of the low-temperature water was about 50 ° C., and the temperature of the high-temperature water was about 115 ° C. The temperature of the circulating water was measured by providing a temperature detector composed of a thermocouple at each of the plugs 67A and 67B at the inlet and the outlet where the circulating water flows into the channel 63 of the mold 36. Also, a thermocouple is provided very close to the mold wall surface, and the measurement result is displayed as the mold wall surface temperature. Until time T1, low-temperature water circulates in the flow path 63 of the mold 36, so that the temperature of the circulating water at the mold entrance and exit and the temperature of the mold wall are almost equal to the temperature of the low-temperature water.
At time T1, the circulating water to the channel 63 in the mold 36 was switched from low-temperature water to high-temperature water. The temperature of the circulating water at the inlet of the mold immediately shows 115 ° C., which is the temperature of the high-temperature water, and the temperature of the circulating water at the outlet of the mold also shows a temperature close to the temperature of the high-temperature water slightly later. The mold wall temperature also rises rapidly so that it can be easily read from FIG. At time T2, the mold wall temperature is about 10
When the temperature reaches 5 ° C., the circulating water is switched and the circulating water is returned from high-temperature water to low-temperature water again.
Time to 25 seconds. That is, the mold wall temperature is 2
This means that the temperature difference increased by 55 ° C. in 5 seconds. The average temperature rise rate for 25 seconds is 2.2 ° C./sec, but the time T1
The temperature rise in the vicinity immediately after the switching shows a large value of 7 to 10 ° C./sec.

When switching to low-temperature water at time T2,
It can be seen that the temperature of the mold wall surface is decreasing at substantially the same speed as when the temperature is increasing.

As described above many times, the above-mentioned high temperature rising rate and cooling rate can be obtained because water is used as the heat medium, and the heat between the water and the wall of the flow path is high. This is because the transfer coefficient is large, but there are other factors as described below.

The first is that the temperature rise rate or the cooling rate also changes depending on the Y dimension of the enlarged sectional view of the flow path 63 shown in FIG. 4, and the above measurement results are obtained when the Y dimension is 6 mm. The smaller the Y dimension, the quicker the response of the mold wall temperature. However, if the Y dimension is too small, the temperature distribution on the mold wall will be uneven, so the Y dimension has an appropriate value naturally.

In FIG. 4, Y represents the distance between the flow path 63 and the wall surface of the cavity 62, d represents the diameter of the flow path 63, X represents the distance between the flow paths 63, and p represents the pitch of the flow path 63.

The second factor that governs the temperature response of the mold wall surface is the time required to switch from high-temperature water to low-temperature water and vice versa. As shown in FIG. 6, the temperature of the circulating water at the outlet of the mold is later than the temperature of the circulating water at the inlet. However, this time delay is, of course, governed by the time during which the circulating water flows from the inlet to the outlet as described above. However, another major factor is a phenomenon in which high-temperature water mixes with low-temperature water that was present in the mold before switching. Conversely, the same is true when low-temperature water is mixed with high-temperature water that was present in the mold before switching. When the high-temperature water and the low-temperature water are mixed, the temperature of the circulating water is naturally intermediate between the two, so that the temperature difference between the circulating water and the wall surface of the flow channel is reduced, and the amount of heat transfer to the flow channel wall surface is reduced. As a result, the temperature response of the mold wall surface becomes slow.

In order to minimize the mixing of high-temperature water and low-temperature water during such switching, the low-temperature switching valve (A) 30, the low-temperature switching valve (B) 31, and the high-temperature switching valve (A) 33 in FIG. , It is necessary to switch the high temperature switching valve (B) 34 at high speed. In the embodiment, as described above, not only the high-temperature water system II but also the low-temperature water system I is maintained at the same pressure as the high-temperature water system II. Switching can be performed at high speed, and the response speed of the mold wall surface temperature can be increased accordingly.

In the above description, the case where the channels 63 in the mold 36 are connected in parallel as shown in FIG. 1 has been described. In some cases. Generally, the parallel connection as shown in FIG. 1 has a smaller pipe resistance, so that a large flow rate can be flowed. Therefore, it is convenient to increase the response speed of the mold wall surface temperature. Since it becomes complicated, it is appropriate to use a relatively large mold.

On the other hand, the series connection shown in FIG. 5 can be used for a small type. In the above description, the low-pressure water system I and the high-temperature water system II shown in FIG.
9 and the suction port of the high-temperature circulation pump 20 are connected so as to communicate with each other, and the low pressure water system I and the high temperature water system II are simultaneously pressurized by applying the discharge pressure of the pressure pump to the connection point. is there. By doing so, the number of pressurizing pumps can be reduced from two to one.

(Embodiment 2) Next, another embodiment of the heating / cooling apparatus of the present invention will be described with reference to FIG. In FIG. 7, I indicates a low-temperature water system, II indicates a high-temperature water system, and III indicates a heated water system.

In FIG. 7, reference numeral 37 denotes a water source. The high-temperature water system II, the low-temperature water system I, and the heating water system III are filled with circulating water through a gate valve 51 by a supply pump 50. Reference numeral 41 denotes a pressurized tank, so that an upper space can be filled with nitrogen gas at a predetermined pressure. 46 is a low temperature switching valve (A), 47 is a low temperature switching valve (B), 48
Is a high temperature switching valve (C), 49 is a high temperature switching valve (D)
It is.

The high-temperature water system II further includes a heating circulation pump 3
Water system III circulated by the heat pump 9 and the high-temperature circulation pump 20
And a circulating system. Hereinafter, the water circulated by the heating circulating pump 39 is referred to as heating water, and the path thereof is referred to as a heating water path, and the water circulating by the high temperature circulating pump 20 is referred to as high temperature water, and the path thereof is referred to as a high temperature water path. To

In the heating water path, reference numeral 29 denotes a heater, and a heating device such as a boiler using electric heat or fossil fuel is used as the heater. Arrow 6 with heating circulation pump 39
The heated water sent out in the direction of 8 is heated by the heater 29 and enters the inlet 44 a of the three-way valve 44 for high temperature control.
Usually, the set temperature of the heating water is set higher than the set temperature of the high-temperature water.

In the high-temperature water path, as described above,
Reference numeral 0 denotes a high-temperature circulation pump, and the high-temperature water discharged in the direction of arrow 75 flows in the direction of arrow 73 through the high-temperature switching valve (C) 48 in the standby state, and is suctioned by the high-temperature circulation pump 20 through the branch pipe 72. Return to mouth. A suction pressure gauge 26 and a discharge pressure gauge 2 are provided at a suction port and a discharge port of the high-temperature circulation pump 20, respectively.
8 and a thermometer 70 at the discharge port.

When the temperature of the thermometer 70 is lower than the set temperature of the high-temperature water, the communication opening between the inlet 44a and the outlet 44c in the passage of the high-temperature temperature control three-way valve 44 increases, Since the opening degree of communication between the outlet 44a and the outlet 44b becomes smaller, more heated water is supplied to the suction port of the high-temperature circulation pump 20, and the temperature of the high-temperature water rises.

When the temperature of the thermometer 70 becomes higher than the set temperature of the high-temperature water, the opening of the communication between the inlet 44a and the outlet 44c in the passage of the three-way valve 44 decreases, and conversely, the inlet 44a Since the opening degree of communication between the outlet and the outlet 44b increases, the flow rate in the direction of the arrow 79 increases, and the return flow rate to the suction port of the heating circulation pump 39 increases. Accordingly, the supply of heating water to the high-temperature water channel system decreases (or disappears), so that the temperature rise in the high-temperature water channel system stops. If the circulation of the heating water continues in this state, the temperature of the heating water further increases by the heater 29, and when the temperature exceeds the set temperature of the heating water, the power of the heater 29 is turned off or the fuel supply to the boiler is stopped. Stop the heating operation.

Next, a low-temperature circulation pump 19
Causes the water to be discharged in the direction of the arrow 76, and in the standby state, passes through the low-temperature switching valve (A) 46,
Flows into the entrance 43a. A suction pressure gauge 25 and a discharge pressure gauge 27 are provided at the suction port and the discharge port of the low-temperature circulation pump 19, respectively.
However, a thermometer 71 is provided at the discharge port.

When the temperature of the thermometer 71 is lower than the set temperature of the low-temperature water, the low-temperature temperature control three-way valve 43 has a large communication opening between the inlet 43a and the outlet 43c. The flow rate flowing in the direction of 77 and returning to the suction port of the low-temperature circulation pump 19 increases.

When the temperature of the thermometer 71 becomes higher than the set temperature of the low-temperature water, the opening of the passage of the low-temperature temperature control three-way valve 43 between the inlet 43a and the outlet 43b increases, and conversely, the inlet 43a Since the opening degree of communication between the outlet 43c and the outlet 43c decreases, the flow rate in the direction of arrow 78 increases, the temperature is adjusted by the temperature adjustment tank 38, and the low-temperature circulation pump 19 returns to the suction port.

The temperature control tank 38 in the second embodiment described above.
In the temperature adjustment in, the cooling operation is usually mainly performed. However, depending on the molding conditions, the temperature of the low-temperature water system I may be lower than the required temperature, and in that case, a slight heating operation may be involved.

The circulation route of the circulating water of the heating water system III, the high temperature water system II and the low temperature water system I has been described above.
Next, means for pressurizing these circulation paths will be described.

As described above, reference numeral 41 denotes a pressurized tank, and the upper space can be filled with nitrogen gas at a predetermined pressure. Since the pressure of the nitrogen gas is applied to the suction port of the heating and circulating pump 39 through the communication pipe 74, the indication of the pressure gauge 40 at the suction port indicates substantially the same value as the pressure gauge 42 of the pressurized tank 41. In general, since the pressure at the suction port of the pump is the lowest pressure in the circulation path, if the suction port pressure falls below the saturation pressure of the circulating water temperature, steam is generated to adversely affect the circulation operation of the pump. As described above, since the pressure of the nitrogen gas is applied to the suction port of the heating circulation pump 39, generation of steam can be suppressed.

Since the pressure of the nitrogen gas is also applied to the suction port of the high-temperature circulating pump 20 through the branch pipe 72, the indication of the pressure gauge 26 at the suction port shows almost the same value as the indication of the pressure gauge 42 of the pressurized tank 41. Actually, the instruction differs depending on the value of the flow path resistance in the branch pipe 72 or the like.
Since the pressure at the suction port 0 can be higher than the saturation pressure of the circulating water temperature, the generation of steam at the suction port of the high-temperature circulating pump 20 is suppressed.

At the outlet of the mold 36, the high-temperature water system II and the low-temperature water system I are connected with the check valves 52 and 53 and the orifices 54 and 5 respectively.
It communicates through 5. Therefore, the above-mentioned pressurized tank 4
1 is supplied to the low temperature water system I through the orifices 54 and 55.
Join.

As described above, since the pressures of the high-temperature water system II and the low-temperature water system I are maintained at the same pressure, it is easy to switch the high-temperature water and the low-temperature water to the mold 36.

As described above, Embodiments 1 and 2
Has the same effect in that it is possible to easily switch between the low-temperature water system I and the high-temperature water system II. In terms of simplicity of the configuration, the first embodiment is superior to the second embodiment in that the configuration is simple and can be handled easily.

However, when the operation is actually continued for a long time by using the first embodiment, a part of the high-temperature water circulated by the high-temperature circulating pump 20 becomes part of the high-temperature pressure regulating valve (B) 2.
4 and back flow through the hot pressurizing pump 18 to the water source 37. The reason for this is not clear, but it is presumed that the thermal expansion due to the temperature rise and the water-hammer phenomenon at the time of switching between high-temperature water and low-temperature water are synergistic. If a check valve is provided in the middle of the pipe to prevent backflow, there is a problem that the pressure of the high-temperature water system rises abnormally due to the thermal expansion of high-temperature water, and the backflow of high-temperature water to the water source could not be prevented. . The pressure is adjusted by the pressure control valve of the pressure pump, but the pressure difference between the high temperature water system and the low temperature water system is lost due to a slight difference in the adjustment of the pressure control valve, and the high temperature water system and the low temperature water There was also a problem that it was difficult to maintain pressure balance. Example 2 showed better results than Example 1 in terms of such operational stability.

In the above description, as an application example of the heating and cooling apparatus for a molding die of the present invention, the case where an injection molding die is used has been described. However, applicable molding dies are not limited to injection molding dies. Molds, such as compression molds,
It can be widely used as a heating / cooling device for a mold generally requiring rapid heating and rapid cooling of a mold wall, such as a blow mold and a RIM mold.

Hereinafter, a case where the heating and cooling apparatus of the present invention is applied to blow molding will be described with reference to FIGS.

FIG. 8 is a cross-sectional view of a molding die in a case where the heating and cooling device for a molding die of the present invention is applied to blow molding. FIG. 9 is a sectional view taken along the arrow line QQ in FIG. FIG. 10 is an explanatory view of a first step in the above-described blow molding step, and FIG. 11 is an explanatory view of a second step in the same manner.

In FIG. 8, the blow molding molds 101, 1
Numeral 02 includes blow molding cores 103 and 104, respectively. The blow molding cores 103 and 104 have cavity wall surfaces 103A and 103 having the same contour system as the outer shape of the molded product.
4A. Furthermore, blow molding cores 103 and 10
Although a plurality of flow paths 63 are engraved on the outer periphery of 4, as shown in FIG. 9, by combining blow molding cores 103 and 104 with blow molding molds 101 and 102, they become heat medium flow paths 63. .

Referring to the mold 101 shown in FIG. 9, a plurality of flow paths 63 communicate with tanks 105 and 106.
The tanks 105 and 106 communicate with supply pipes 113 and 114 through communication pipes 109 and 110, respectively. Supply pipe 113,1
Reference numeral 14 is connected to the heating and cooling device described above. Since the mold 102 has the same configuration, the description is omitted.

In FIG. 8, the molds 101 and 102 reciprocate in the directions of arrows 117 and 118, respectively, to open and close the molds. FIG. 10 shows a state in which the molds 101 and 102 are open.

The general process of blow molding is to extrude the parison 119 from the extrusion nozzle 120 in the state shown in FIG. 10 as the first process. When the parison 119 having a predetermined length is extruded, the molds 101 and 102 are closed as shown in FIG. 11 as a second step, and high-pressure air of atmospheric pressure or higher is blown from the air nozzle 121 to form the parison 119 as a core cavity. It is pressed against the wall surfaces 103A and 104A to form a predetermined product outer shape. Then, the cores 103 and 104,
Cool and take out the product.

The above is the general blow molding process. As described above, the outer shape of the product is determined by the parison 119 being pressed against the cavity wall surfaces 103A and 104A by high-pressure air. Although high-pressure air is used, its value is at most several to several tens of atmospheres. In injection molding, the molten resin is pressed against the cavity wall surface with a much smaller pressure than when an injection pressure of several hundred atmospheres is applied. Therefore, one of the drawbacks is that blow molding generally has poor transferability of the mold wall surface as compared with injection molding.

However, as shown in FIGS. 8 and 9, the blow mold is a mold provided with a plurality of flow paths 63 near the cavity wall surfaces 103A and 104A, and the heating and cooling apparatus of the present invention is applied to this mold. Cavity wall surface 103A, 1
04A can be rapidly heated and cooled. Therefore, in FIG. 10, high temperature water is flowed through the flow passage 63 in advance to raise the temperature of the cavity wall surfaces 103A and 104A before the molds 101 and 102 are opened and the parison is blown. As a result, when high-pressure air is blown in FIG. 11, the parison 119 is pressed against the cavity walls 103A and 104A, which have a higher temperature than in the case of normal blow molding. Transferability to the surface can be significantly improved.

In cooling, since the flow path 63 is near the cavity wall surfaces 103A and 104A, the cooling effect is improved, the cooling time can be shortened, and the molding cycle time is also shortened.

In the above description, it has been stated that for rapid heating and rapid cooling, it is more advantageous to use clear water as a heat medium, and for that purpose, pressurization of clear water as a heat medium is required. .

However, depending on the molding conditions, a heat medium other than fresh water, for example, an oil-based heat medium may be used, and when the heat medium is used at a temperature close to the saturation temperature, the heat medium is pressed to a pressure higher than the saturation pressure. Need. When the heat medium other than the fresh water needs to be pressurized at a pressure higher than the saturation pressure of the heat medium, the heating and cooling device for a mold of the present invention can be effectively used.

[0087]

Since the present invention is carried out in the state described above, the following effects can be obtained.
A flow path is provided near the cavity of the mold, and in a molding die having a structure in which a heat medium flows through the flow path, pressure is applied to the high-temperature water system and the low-temperature water system by a pressurizing pump or gas pressure. It became possible to use water at 100 ° C. or higher. Since water has a large heat transfer coefficient with the flow path wall as a heat medium, as a result, it has become possible to increase the temperature rise rate and the cooling rate of the mold wall. In addition, since the high-temperature water system and the low-temperature water system have the same pressure, the circulating water to the mold can be quickly switched from high temperature to low temperature, and the temperature responsiveness of the mold wall surface can be made quick. Was.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a heating and cooling device for a molding die according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an injection mold used for the heating and cooling device of the mold of the present invention.

FIG. 3 is a cross-sectional view taken along a line MM of FIG. 2;

FIG. 4 is an enlarged sectional view of a circle N in FIG. 2;

FIG. 5 shows another embodiment of the configuration of the flow path of the molding die used in the present invention.

FIG. 6 shows an example of a response measurement diagram of a mold wall surface temperature by the heating and cooling device for a mold according to the present invention.

FIG. 7 is a configuration diagram of another embodiment of a heating and cooling device for a molding die according to the present invention.

FIG. 8 is a cross-sectional view of a blow mold used for the heating and cooling device of the mold of the present invention.

9 is a sectional view taken along the line QQ in FIG. 8;

FIG. 10 is an explanatory view of the first step when the heating and cooling device for a mold according to the present invention is used for blow molding.

FIG. 11 is an explanatory view of the second step when the heating and cooling device of the mold of the present invention is used for blow molding.

FIG. 12 is a configuration diagram of a conventional heating and cooling device.

[Explanation of symbols]

 I Low-temperature water system II High-temperature water system III Heating water system 17 Low-temperature pressurizing pump 18 High-temperature pressurizing pump 19 Low-temperature circulating pump 20 High-temperature circulating pump 29 Heater 36 Type 38 Temperature control tank 39 Heating circulating pump 41 Pressurized tank 43 Low-temperature temperature control 3 way Valve 44 High temperature temperature control three-way valve 63 Flow path

Claims (9)

[Claims] 1. A high-temperature heat medium circulating path for circulating a high-temperature heat medium and a low-temperature heat medium system for circulating a low-temperature heat medium using a mold provided with a heat medium flow path close to the wall surface of the cavity. A circulation path is at least a component, and a flow path of the heat medium of the molding die is inserted into a part of a circulation path of the high-temperature heat medium system to form a high-temperature circulation path. Is inserted into a part of the circulation path of the low-temperature heat medium system to form a low-temperature circulation path, the high-temperature circulation path and the low-temperature circulation path can be switched, and the temperature of the high-temperature heat medium circulating through the high-temperature circulation path A heating and cooling device for a mold, wherein a pressure equal to or higher than the saturation pressure is applied to the high-temperature circulation path and the low-temperature circulation path. 2. A molding die provided with a flow path of a heating medium close to a cavity wall surface has at least a high-temperature water circulation path for circulating high-temperature water and a low-temperature water circulation path for circulating low-temperature water. Inserting the flow path of the heat medium into a part of the circulation path of the high-temperature water system to form a high-temperature circulation path, and inserting the flow path of the heat medium into a part of the circulation path of the low-temperature water system to perform low-temperature circulation A path is formed, the high-temperature circulation path and the low-temperature circulation path are switchable, and a pressure equal to or higher than the saturation pressure corresponding to the temperature of the high-temperature water circulating in the high-temperature circulation path is applied to the high-temperature circulation path and the low-temperature circulation path. Heating and cooling device for the applied mold. 3. A high-temperature water circulation path for circulating high-temperature water, a low-temperature water circulation path for circulating low-temperature water, and a pressurizing means. And at least switching means, wherein the high-temperature water system circulation path has at least a high-temperature water circulation pump and a heater,
The circulation path of the low-temperature water system has at least a low-temperature water circulation pump and a temperature control tank, and a high-temperature circulation path formed by inserting the flow path of the heat medium into a part of the circulation path of the high-temperature water system and a flow path of the heat medium. A low-temperature circulation path formed by inserting a path into a part of the low-temperature water circulation path can be switched by the switching means, and the high-temperature circulation path and the low-temperature circulation path have high-temperature water circulating through the high-temperature circulation path. A heating and cooling device for a molding die to which a pressure equal to or higher than a saturation pressure corresponding to a temperature is applied by the pressurizing means. 4. The heating and cooling apparatus for a molding die according to claim 3, wherein a pressure pump is used as the pressure means, and the discharge pressure of the pressure pump is equal to or higher than the saturation pressure. 5. The heating and cooling apparatus for a mold according to claim 3, wherein a pressurizing tank containing a pressurized gas and a liquid is used as pressurizing means, and a pressure higher than a saturation pressure is applied by the pressurizing tank. 6. The heating and cooling device for a mold according to claim 5, wherein the pressure of the pressurized gas is set to a pressure equal to or higher than the saturation pressure. 7. A high-temperature water circulation circuit for circulating high-temperature water, a low-temperature water circulation circuit for circulating low-temperature water, and a pressurizing means. And a switching means, wherein the circulation path of the high-temperature water system has at least a circulation path of a high-temperature water circulation pump and a circulation path of a heating water system that circulates heating water having a higher temperature than the high-temperature water by the heating water circulation pump. The path has at least a low-temperature water circulation pump and a temperature adjustment tank, and the high-temperature circulation path formed by inserting the flow path of the heat medium into a part of the high-temperature water system circulation path and the flow path of the heat medium are connected to the low-temperature water system. The switching means can be switched to a low-temperature circulation path formed by inserting a part of the circulation path, and the temperature of the heating water circulating through the heating water system by the pressurizing means is provided on the suction side of the heating water circulation pump. You A heating and cooling device for a molding die in which a pressure equal to or higher than a saturation pressure is applied to pressurize the high-temperature circulation path and the low-temperature circulation path. 8. A circulation path of the heating water system includes a heating water circulation pump, a heater, and a three-way control valve, and a discharge side of the heating water circulation pump communicates with an inlet of the three-way control valve through the heater. One outlet of the three-way control valve communicates with the suction port of the heated water circulation pump, and the other outlet communicates with the suction port of the high-temperature water circulation pump, and the suction side of the high-temperature water circulation pump and the suction side of the heated water circulation pump. And the above 3
8. The heating and cooling device for a molding die according to claim 7, wherein the temperature is adjusted by mixing the heating water with the high-temperature water according to the degree of opening of the direction control valve. 9. A low-temperature water circulation path includes at least a low-temperature water circulation pump, a temperature control tank, and a three-way control valve, and a path of water discharged from the low-temperature water circulation pump passes through a molding die flow path. One-way outlet of the three-way control valve is connected to the suction port of the low-temperature water circulation pump, and the other outlet is connected to the suction port of the low-temperature water circulation pump via the temperature adjustment tank; 8. The temperature is adjusted by mixing water that has passed through the temperature control tank and water that has not passed through the temperature control tank according to the degree of opening of the three-way control valve, and flows into the suction port of the low-temperature water circulation pump. Heating and cooling device for molds.