Mold-Cooling System and Mold-Cooling Method

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention relates to a mold-cooling system and a mold-cooling method for cooling a heated mold.

2. Description of the Related Art

For cooling a heated mold, a mold-cooling system (a mold-cooling apparatus) supplying cooling medium such as cooling water to a medium flow path provided for a mold has been known conventionally. In the above-mentioned mold-cooling system, there has been a problem that cooling medium supplied to the medium flow path of the mold heated to a high temperature gasifies in the medium flow path and the vapor is discharged. Patent Literature 1 below, for instance, discloses a temperature-control device for the mold constituted in such a manner that a conduit pipe for supplying liquid at ordinary temperatures and a drain pipe are connected to a liquid circulating passage constituted by connecting a liquid passage of the mold with that of a temperature controller, and the conduit pipe for liquid supply and the drain pipe are connected by a throttle passage, thereby supplying the ordinary temperature liquid passing through the throttle passage to the drain pipe and suppressing generation of the vapor.

CITATION LIST
Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2002-52538

SUMMARY OF THE INVENTION
Problems to be Solved by the Invention

Recently, due to large size of articles to be molded, diversification of molding material or the like, a system for cooling the mold at a high temperature approximately from 150 degrees Celsius to 300 degrees Celsius is desired. In such a cooling system, when cooling medium is fed into the medium flow path of the mold, the cooling medium instantly gasifies and pressure increases in the medium flow path of the mold; also accompanied with relatively large heat capacity of the mold, it is difficult to feed cooling medium into the medium flow path of the mold from a supply source side of cooling medium, cooling time is prolonged, and a pump of high discharge pressure is required. As shown in Patent Literature 1, for instance, condensation by supplying liquid to a path on a discharge side of the mold is also possible; similar to a medium feeding side, it is difficult to supply liquid due to the increase in pressure, and the pump of high discharge pressure is required.

In view of the above-mentioned problems, an object of the present invention is to provide a mold-cooling system and a mold-cooling method which suppress discharge of gasified cooling medium and enhance cooling efficiency.

Means of Solving the Problems

In order to achieve the above-mentioned object, in a mold-cooling system of the present invention for cooling a heated mold by supplying cooling medium from a cooling medium supply source to a medium flow path provided for a mold, a discharge side path connected to an outlet side of the medium flow path of the mold can be communicated with a heat exchanger condensing the cooling medium gasified and discharged from the medium flow path.

In the present invention, a path supplying steam from a steam source or air from an air source can be connected to a supply side path connected to an inlet side of the medium flow path of the mold from the cooling medium supply source, and the mold-cooling system can include a control portion controlling supply of the steam or the air and supply of the cooling medium, and supplying the cooling medium to the medium flow path of the mold after supplying the steam or the air to the medium flow path of the mold.

In the present invention, the path supplying steam from the steam source or air from the air source can be connected to the supply side path connected to the inlet side of the medium flow path of the mold from the cooling medium supply source, and the mold-cooling system can include the control portion controlling the supply of the steam or the air and the supply of the cooling medium, and supplying the steam or the air to the medium flow path of the mold after supplying the cooling medium to the medium flow path of the mold.

In the present invention, the discharge side path on a downstream side of the heat exchanger can be provided with a backflow prevention portion preventing backflow.

In order to achieve the above-mentioned object, in a mold-cooling method of the present invention for cooling the heated mold by supplying cooling medium to the medium flow path provided for the mold, the discharge side path connected to the outlet side of the medium flow path of the mold is communicated with the heat exchanger, and the cooling medium gasified and discharged from the medium flow path is condensed in the heat exchanger.

In the present invention, the cooling medium can be supplied to the medium flow path of the mold after executing a precooling step in which steam or air is supplied to the medium flow path of the mold.

In the present invention, a second cooling step in which steam or air is supplied to the medium flow path of the mold can be performed after executing a first cooling step in which the cooling medium is supplied to the medium flow path of the mold.

Effects of the Invention

The mold-cooling system and the mold-cooling method of the present invention, constituted as mentioned above, suppress discharge of gasified cooling medium and enhance the cooling efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system configuration diagram which schematically shows one example of the mold-cooling system in one embodiment of the present invention.

FIG. 2 is a schematic time chart which shows one example of basic operation executed in the mold-cooling system.

FIG. 3 is the system configuration diagram which schematically shows one example of the mold-cooling system in another embodiment of the present invention.

FIG. 4 is the schematic time chart which shows one example of basic operation executed in the mold-cooling system.

FIG. 5 is the system configuration diagram which schematically shows one example of the mold-cooling system in still another embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention is explained below with reference to the drawings. In FIG. 1, FIG. 3, and FIG. 5, pipe lines (pipe arrangement), i.e. paths through which medium, or the like passes, are schematically shown in a solid line.

The schematic time charts in FIG. 2 and FIG. 4 diagrammatically show ON and OFF operations, opening and closing operations or the like of respective devices.

FIG. 1 and FIG. 2 illustrate a mold-cooling system in a first embodiment and a mold-cooling method carried out with the mold-cooling system.

A mold-cooling system 1 in the embodiment is constituted for cooling a heated mold 2 in such a manner that cooling medium from a cooling medium supply source 10 is supplied to a medium flow path 4 provided for the mold 2. As shown in FIG. 1, the mold-cooling system 1 is constituted in such a manner that a discharge side path 15 connected to an outlet 5 side of the medium flow path 4 of the mold 2 is communicated with a heat exchanger 20 condensing gasified cooling medium discharged from the medium flow path 4.

In the embodiment, the mold-cooling system 1 is a mold heating-cooling system 1 which performs heating in addition to cooling of the mold 2.

The mold 2 is, for instance, constituted with a fixed mold and a movable mold; the fixed mold and the movable mold are respectively provided with the medium flow paths 4, 4 for circulating cooling medium. A supply side path 13 (a medium feeding path) is connected to inlets 3, 3 (medium feeding connection ports) side of the medium flow paths 4, 4. The discharge side path 15 (a medium returning path) is connected to outlets 5, 5 (medium returning connection ports) side of the medium flow paths 4, 4.

The supply side path 13 and the inlets 3, 3 of the medium flow paths 4, 4 can be connected by a manifold portion which divides a single supply side path 13 into plurality or by flexible piping members, such as a hose or a tube which is connected to a plurality of connection ports of the manifold portion.

The discharge side path 15 and the outlets 5, 5 of the medium flow paths 4, 4 can be substantially similarly connected by a manifold portion which branches a single discharge side path 15 into plurality or by flexible piping members, such as a hose or a tube which is connected to a plurality of connection ports of the manifold portion.

The mold 2 is provided with a temperature sensor 6 as a detection means for detecting the temperature of the mold 2. The temperature sensor 6 can be constituted so as to detect the temperature of medium (cooling medium) on the outlet 5 side, a vicinity region of the outlet 5 of the medium flow path 4, a downstream vicinity region of the outlet 5, or the like. The mold 2 is provided with a mold heater 7 as a heating means for heating the mold 2. The figure shows an example in which the mold heaters 7, 7 are respectively embedded in the fixed mold and the movable mold of the mold 2.

A target heating temperature (a set heating temperature, referring to FIG. 2) of the mold 2 heated by the mold heater 7 as the heating means can be appropriately set according to the size or the shape of an article to be molded, the type of molding material or the like and in view of improving fill ability of molten material or transfer property (transfer rate) of a cavity face to the article to be molded. When the article to be molded is relatively large in size, the target heating temperature can be set relatively high, for instance approximately from 150 degrees Celsius to 300 degrees Celsius or approximately from 200 degrees Celsius to 300 degrees Celsius.

A target cooling temperature (a set cooling temperature, referring to FIG. 2) of the mold 2 cooled by cooling medium from the cooling medium supply source 10, to be mentioned below, can be also appropriately set from a similar point of view as mentioned above, from the point of view of capable of solidifying molten material and shortening a molding cycle, or the like. The target cooling temperature can be set lower than the target heating temperature. However, when the target cooling temperature is too low, accompanied with large heat capacity of the mold 2, time for cooling down to the target temperature and time for heating up to the target temperature in a next step are likely to be prolonged. From the above-mentioned view or the like, the target cooling temperature can be, for instance, approximately from 100 degrees Celsius to 200 degrees Celsius or approximately from 150 degrees Celsius to 200 degrees Celsius. When the target heating temperature is set relatively high as mentioned above, the target cooling temperature can be set lower than the target heating temperature approximately by 40 degrees Celsius to 120 degrees Celsius.

A molding machine of the mold 2 can be an injection molding machine or the like in which synthetic resin, i.e. material molten by a cylinder or the like, is injected from a nozzle or the like and filled into a cavity or the like formed by the fixed mold and the movable mold of the mold 2, thereafter the article is molded successively. Other molding machines such as a compression molding machine can be adopted. Molding material can be fiber-reinforced synthetic resin material or the like, i.e. synthetic resin material containing reinforced-fiber such as carbon fiber or glass fiber.

The heating means for the mold 2 is not limited to the mold heater 7 mentioned above; it can be a heating medium supply source which supplies heating medium to the medium flow path provided for the mold 2. In such a case, the heating medium can be fed into the cooling medium flow path, or an aspect can be such that the heating medium is fed into the medium flow path exclusively for the heating medium. Other kinds of heating means can be adopted. Furthermore, heating of the mold 2 can be performed by autothermal of molten material injected into the cavity of the mold 2.

As for the cooling medium supply source 10, appropriate supply sources can be adopted according to types of cooling medium, required temperatures of cooling medium, the target cooling temperature or the like. For instance, the cooling medium supply source 10 can be constituted with a storage portion (a tank) which stores cooling medium, and with a cooling medium supply pump 11 (referring to FIG. 2) which supplies (feeds) cooling medium stored in the storage portion towards a mold 2 side. In such a case, temperature can be appropriately controlled by a cooler such as a chiller so that cooling medium stored in the storage portion is maintained at the predetermined temperature.

Cooling medium supplied from the cooling medium supply source 10 is liquid on a supply side and is water (clean water) in the embodiment; alcohol including ethanol, or other cooling medium can be adopted. Cooling medium of which boiling point at ordinary pressures is equal to or less than 100 degrees Celsius can be adopted.

The temperature of cooling medium supplied from the cooling medium supply source 10 can be set at ordinary temperatures or can be, for instance, approximately from 5 degrees Celsius to 90 degrees Celsius or approximately from 10 degrees Celsius to 50 degrees Celsius. The cooling medium supply source 10 is not limited to the one as mentioned above and can have a storage portion in which temperature control is not performed. The cooling medium supply source can be a cooling tower or the like installed in a plant or the like, or can be a water supply system (industrial water works, water works).

In the embodiment, the mold heating-cooling system 1 is constituted in such a manner that paths 18, 19 respectively supplying steam from a steam source 8 and air from an air source 9 are connected to supply side paths 12, 13 connected to an inlet 3 side of the medium flow path 4 of the mold 2 from the cooling medium supply source 10.

The steam source 8 can be a boiler or the like which heats and vaporizes, or gasifies liquid (preferably liquid of the same kind as cooling medium supplied to the medium flow path 4 of the mold 2 from the cooling medium supply source 10) with a heat source.

The steam supply path 18 which supplies steam from the steam source 8 is provided with a steam valve 18a such as a solenoid valve which supplies or cuts off steam from the steam source 8. One end of the steam supply path 18 is connected to the steam source 8 and the other end is connected to the supply side path 13 by an appropriate coupling or the like. The temperature of steam supplied from the steam source 8 can be appropriately set according to the above-mentioned target cooling temperature, for instance, substantially the same temperature as or lower than the above-mentioned target cooling temperature.

The air source 9 can be constituted in such a manner that the atmosphere or the like is sent by a blower; it can be a compression air source of a gas tank or the like which stores gas (high-pressure gas) compressed by a compression machine such as a compressor through an aftercooler, a drain separator, a dryer, or the like.

The air supply path 19 which supplies air from the air source 9 is provided with an air valve 19a such as a solenoid valve which supplies or cuts off air from the air source 9. One end of the air supply path 19 is connected to the air source 9 and the other end of the air supply path 19 is connected to the supply side path 13 by an appropriate coupling or the like.

The supply side paths 12, 13 which connect the cooling medium supply source 10 with the inlet 3 of the medium flow path 4 of the mold 2 are constituted with an upstream supply side path 12 (a cooling medium supply source 10 side) further than a connecting portion, as mentioned above, of the steam supply path 18 and the air supply path 19, and with a downstream supply side path 13 (the mold 2 side) further than the connecting portion.

The upstream supply side path 12 of the supply side paths 12, 13 is provided with a cooling medium valve 12a such as a solenoid valve which supplies or cuts off cooling medium from the cooling medium supply source 10. The cooling medium supply pump 11 as mentioned above is disposed at the upstream supply side path 12. The upstream supply side path 12, the above-mentioned storage portion or the like is provided with the detection means such as a temperature sensor which detects the temperature of cooling medium fed into the medium flow path 4 of the mold 2; based on the detection value of the detection means, temperature can be controlled by the above-mentioned cooler or the like so that the temperature of cooling medium becomes the predetermined temperature.

The heat exchanger 20, in which cooling medium fed through the discharge side path 15 connected to the outlet 5 of the medium flow path 4 of the mold 2 is high-temperature fluid, is communicated with a cooling path 14 into which low-temperature fluid which cools and condenses the high-temperature fluid is fed. The discharge side path 15 and the cooling path 14 can be respectively connected to a fluid passage on a high-temperature side and a fluid passage on a low-temperature side of the heat exchanger 20.

In the heat exchanger 20, cooling medium gasified through the medium flow path 4 of the mold 2 heated to a high temperature is heat-absorbed by low-temperature fluid which is fed through the cooling path 14, cooled condensed, and liquefied.

In the embodiment, the cooling path 14 is constituted to feed cooling medium supplied from the cooling medium supply source 10 into the fluid passage on the low-temperature side of the heat exchanger 20. Namely, the cooling medium supply source 10 which supplies cooling medium to the medium flow path 4 of the mold 2 is constituted so as to be also used as the supply source which supplies cooling medium to the fluid passage on the low-temperature side of the heat exchanger 20. As mentioned above, the constitution is further simplified as compared with a case in which the cooling medium supply source for the heat exchanger 20 is separately provided.

The cooling path 14 is connected by an appropriate coupling or the like on the upstream side further than a region for which the cooling medium valve 12a of the upstream supply side path 12 is provided. In other words, the upstream supply side path 12 is divided into the supply side path 12 heading toward the mold 2 side and the cooling path 14 heading toward a heat exchanger 20 side on the upstream side further than the region for which the cooling medium valve 12a is provided.

The cooling path 14 is provided with a heat exchanger cooling valve 14a such as a solenoid valve which supplies or cuts off cooling medium from the cooling medium supply source 10. The cooling path 14 is connected to a medium returning side of the cooling medium supply source 10.

In the embodiment, the discharge side path 15 (on a downstream side of the heat exchanger 20) connected to the outlet 5 of the medium flow path 4 of the mold 2 and passing through the heat exchanger 20 is connected on the medium returning side of the cooling medium supply source 10. Namely, cooling medium supplied to the medium flow path 4 of the mold 2 is circulated in a closed-loop manner with the cooling medium supply source 10. As constituted above, impurities are unlikely to be mixed and quality control of cooling medium is easily performed.

The figure shows an example in which the discharge side path 15 on the downstream side of the heat exchanger 20 is connected to the cooling path 14 on the downstream side of the heat exchanger 20 in a confluent manner.

In the embodiment, the discharge side path 15 on the downstream side of the heat exchanger 20 is provided with a backflow prevention portion 16 for preventing backflow.

The backflow prevention portion 16 in the embodiment is a backflow prevention valve (a non-return valve, a check valve) which permits a fluid flow from the heat exchanger 20 side into the cooling medium supply source 10 side and blocks a fluid flow from the cooling medium supply source 10 side into the heat exchanger 20 side. By adopting such a backflow prevention valve as the backflow prevention portion 16, an opening and closing control or the like becomes unnecessary on discharging (returning the medium) and backflow is prevented by a simple control, as compared with the conventional one provided with an opening and closing valve or the like as the backflow prevention portion.

As for the above-mentioned heat exchanger 20, heat exchangers of various types such as a double pipe heat exchanger, a plate heat exchanger, a shell and tube heat exchanger, and a cross fin heat exchanger can be adopted. While the figure shows the heat exchanger 20 of a parallel flow type, heat exchangers of a counter flow type, a cross flow type or the like can be used.

The discharge side path 15 on the downstream side of the heat exchanger 20 (the discharge side path 15 on an upstream side further than the backflow prevention portion 16) can be appropriately provided with a steam trap or the like if necessary.

While the figure shows an embodiment in which opening and closing valves (ON and OFF valves) are respectively provided to open and close the upstream supply side path 12, the cooling path 14, the steam supply path 18, and the air supply path 19, all or some of the above-mentioned valves can be constituted by a multiport and multi-position type changeover valve or the like.

The mold heating-cooling system 1 has a control panel 21 including a control portion 22 which controls the mold heater 7, the cooling medium supply pump 11, and the valves 12a, 14a, 18a, 19a.

The control panel 21 has the control portion 22 such as a CPU, a display operation portion 24, and a memory portion 23, which are respectively connected by signal lines. The display operation portion 24 constitutes a display portion and an operation portion for setting up, inputting or displaying. The memory portion 23 is constituted by various memories and stores information about conditions and values inputted and set up by an operation of the display operation portion 24, various programs such as a control program for executing respective operations mentioned below, various predetermined operation conditions, various data tables or the like.

The control portion 22 has a timing means such as a clock timer, and an arithmetic processing portion and is connected to the mold heater 7, the cooling medium supply pump 11, and the valves 12a, 14a, 18a, 19a through the signal line or the like for controlling. The control portion 22 is also connected to the temperature sensor 6 of the mold 2 through the signal line or the like.

In the embodiment, the control portion 22 is constituted to control the supply of steam or air and also the supply of cooling medium.

In the embodiment, as shown in FIG. 2, the control portion 22 is constituted to control so as to supply cooling medium to the medium flow path 4 of the mold 2 after supplying steam to the medium flow path 4 of the mold 2.

In the embodiment, as shown in FIG. 2, the control portion 22 is constituted to control and supply air to the medium flow path 4 of the mold 2 after supplying cooling medium to the medium flow path 4 of the mold 2.

The mold-cooling apparatus constituting the mold heating-cooling system 1 could be the one having opening and closing valves 12a, 14a, 18a, 19a disposed at the above-mentioned paths 12, 14, 18, 19, the backflow prevention portion 16, the heat exchanger 20, and the control panel 21 as shown in two-dot chain lines of FIG. 1. Furthermore, the above apparatus could be the one having at least one of the steam source 8, the air source 9, and the cooling medium supply source 10. In addition, the above apparatus could be a mold heating-cooling apparatus which further has the heating means 7 for heating the mold 2.

In the mold heating-cooling system 1 in the embodiment constituted as above, the mold 2 is heated when the mold heater 7 is activated. The mold heater 7 can be such that energization control such as a PID control is performed by the control portion 22 in order that the temperature of the mold 2 becomes the predetermined target heating temperature based on a measurement temperature signal (a detection temperature) of the temperature sensor 6 of the mold 2. The above-mentioned target heating temperature can be inputted and set up through the display operation portion 24.

When the cooling medium supply pump 11 is activated and the cooling medium valve 12a is opened, cooling medium from the cooling medium supply source 10 is supplied (supplied in circulation in the embodiment) to the medium flow path 4 of the mold 2.

When the cooling medium supply pump 11 is activated and the heat exchanger cooling valve 14a is opened, cooling medium from the cooling medium supply source 10 is supplied to the fluid passage on the low-temperature side of the heat exchanger 20. The opening and closing control of the above-mentioned heat exchanger cooling valve 14a, such as the PID control, can be performed by the control portion 22 in order that the temperature of returned cooling medium becomes the predetermined target temperature based on the measurement temperature signal (the detection temperature) of the temperature sensor. The temperature sensor detects the temperature on the downstream side of the heat exchanger 20 of the discharge side path 15 which is communicated with the fluid passage on the high-temperature side of the heat exchanger 20. The above-mentioned target temperature can be inputted and set up through the display operation portion 24.

When the steam valve 18a is opened, steam from the steam source 8 is supplied to the medium flow path 4 of the mold 2.

When the air valve 19a is opened, air from the air source 9 is supplied to the medium flow path 4 of the mold 2.

One example of a mold heating-cooling method (the mold-cooling method) is explained based on FIG. 2 as one example of basic operation executed in the mold heating-cooling system 1 in the embodiment constituted as above.

In a graph of FIG. 2, a horizontal axis is a time axis, a vertical axis is the detection temperature of the temperature sensor 6, and its transition is schematically shown.

First, the mold heater 7 is activated and a preheating step can be executed to preheat the mold 2 substantially at ordinary temperatures approximately to the target cooling temperature. A standby state is obtained when the preheating step is executed as above.

In the molding machine of the mold 2 not shown in the figure, molten material such as resin is injected and filled into the cavity provided for the mold 2 in a closed condition, and pressure is appropriately kept; when molten material is solidified, the mold is opened, and the article is demolded. In such a series of molding steps, the mold heating-cooling system 1 in the embodiment is used for executing a mold heating step in order that the solidification of molten material is retarded and filling is smoothly performed. After molten material is filled into the cavity, the mold heating-cooling system 1 in the embodiment is used for executing a mold cooling step for rapidly solidifying molten material. The mold heating step and the mold cooling step which are executed by the mold heating-cooling system 1 can be executed (started and stopped) together with a molding operation of the molding machine, for instance, based on a mold closing signal, an injection signal, a pressure keeping signal, a mold opening signal of the molding machine.

When preheating is performed as mentioned above and a signal on a molding machine side or another heating start signal is received in the standby state, a heating step for heating the mold 2 is executed and the mold 2 is heated to the predetermined target heating temperature. The heating step can be finished when the signal on the molding machine side or another heat finish signal is received, or can be finished after reaching the target heating temperature and the elapse of predetermined time.

When the heating step is finished and the predetermined time elapses or the signal on the molding machine side or another cooling start signal is received, a cooling step for cooling the mold 2 is executed and the mold 2 is cooled to the predetermined target cooling temperature. The target cooling temperature can be inputted and set up through the display operation portion 24.

In the embodiment, since the heat exchanger cooling valve 14a which supplies or cuts off low-temperature medium (cooling medium) is provided for the fluid passage on the low-temperature side of the heat exchanger 20, the opening and closing control of the heat exchanger cooling valve 14a is performed during the cooling step. As in a second and a third embodiments mentioned below, in such an aspect without the heat exchanger cooling valve 14a, the low-temperature medium (cooling medium) can be constantly supplied to the fluid passage on the low-temperature side of the heat exchanger 20.

In the example of the operation, the precooling step in which steam is supplied to the medium flow path 4 is executed before cooling medium is supplied to the medium flow path 4. In other words, in such a state that the cooling medium valve 12a is closed, the steam valve 18a is opened and steam is supplied to the medium flow path 4. When steam is supplied as mentioned above, due to its contact to an inner circumferential face of the medium flow path 4, the heat is absorbed, precooling is performed, and steam is condensed in the heat exchanger 20. Thereby, pressure drops in the respective paths, i.e. the supply side path 13, the medium flow path 4, and the discharge side path 15. Namely, steam and cooling medium which is adhered to the inner circumferential face of the medium flow path 4 are gasified, successively condensed and liquefied in the heat exchanger 20, thereby the pressure in the respective paths sharply drops also accompanied with the backflow prevention portion 16 provided.

The above-mentioned precooling step can be executed in such a manner that the supply side path 13, the medium flow path 4, and the discharge side path 15 are almost filled with steam. The precooling step can be executed until the predetermined time elapses or until a measurement pressure signal (detection pressure) of a detection means which detects the pressure in the paths such as a pressure sensor provided for any of the supply side path 13, the medium flow path 4, and the discharge side path 15 falls below the predetermined pressure (a threshold value). In other words, when the pressure falls below the predetermined pressure, supply of steam can be switched into supply of cooling medium. The predetermined pressure, for instance, can be at which the next supply of cooling medium is possible; it can also be appropriately set according to capacity (discharge pressure) or the like of the cooling medium supply pump 11. The predetermined pressure can be inputted and set up through the display operation portion 24.

In the precooling step, steam can be mixed with a small amount of cooling medium and supplied, or air can be supplied instead of steam. In such a case, air can be mixed with a small amount of cooling medium or steam and supplied.

After the above precooling step, a main cooling step in which cooling medium is supplied to the medium flow path 4 of the mold 2 is executed. In other words, when the cooling medium supply pump 11 is activated, and the steam valve 18a is closed, the cooling medium valve 12a is opened. The figure shows an example in which, considering rise time or the like, the cooling medium supply pump 11 is activated earlier than an opening of the cooling medium valve 12a.

In the example of the operation, after a first cooling step constituted by the main cooling step, a second cooling step in which air is supplied to the medium flow path 4 of the mold 2 is executed. In other words, when the cooling medium valve 12a is closed, and the air valve 19a is opened, air is supplied to the medium flow path 4. On closing the cooling medium valve 12a, the cooling medium supply pump 11 can be stopped. An aspect can be such that a bypass path which connects the supply side path 12 with the discharge side path 15 (the cooling path 14 in the figure) is provided, a bypass valve provided for the bypass path is conversely opened and closed relative to the opening and the closing of the cooling medium valve 12a, thereby generally activating the cooling medium supply pump 11 constantly.

The first cooling step and the second cooling step can be respectively executed until the predetermined time elapses in such a manner that cooling medium in the medium flow path 4 is generally discharged (purged) by executing the second cooling step and without excessive cooling or the like; in other words, the temperature does not greatly fall below the target cooling temperature on finishing the cooling step. Based on the detection temperature of the temperature sensor 6, the first cooling step can be switched into the second cooling step and the second cooling step can be finished; in other words, the air valve 19a can be closed. In the second cooling step, in place of or in addition to air, a small amount of cooling medium can be intermittently supplied or steam can be supplied as in an example of an operation in the second embodiment mentioned below. In such a case in which steam is supplied, a small amount of cooling medium can be intermittently supplied in addition to steam. When steam or a small amount of cooling medium is supplied as mentioned above, the supply can be appropriately controlled in such a manner that the total amount in the medium flow path 4 almost gasifies and the medium in the medium flow path 4 almost does not remain at the end of the second cooling step. For instance, heat quantity released from an inner wall face of the medium flow path 4 is calculated based on capacity of the medium flow path 4, mold temperatures before and after filling of molten material such as resin; it can be experimentally or empirically determined based on the heat quantity, gasification heat quantity of the medium, the target cooling temperature, or the like. Since gasification occurs in a mold opening or a demolding step, a relatively small amount of remaining medium can be allowed.

After the cooling step, in the mold 2, the mold opening and the demolding of the molded article are appropriately executed, and the heating step and the cooling step are repeatedly executed.

The heating step in which the mold 2 is heated and the cooling step in which the mold 2 is cooled, executed as mentioned above, improve transfer property (transfer rate) of the cavity face to the molded article and shorten the molding cycle.

The mold-cooling system 1 (the mold heating-cooling system) in the embodiment and the mold-cooling method (the mold heating-cooling method) which is executed by the mold-cooling system 1 constituted as mentioned above enhance cooling efficiency while suppressing discharge of gasified cooling medium.

In other words, the discharge side path 15 connected to the outlet 5 side of the medium flow path 4 of the mold 2 is communicated with the heat exchanger 20 condensing gasified cooling medium discharged from the medium flow path 4. Accordingly, gasified cooling medium is condensed in the heat exchanger 20 and discharge of gasified cooling medium is suppressed. By condensing in the heat exchanger 20, pressure raised by gasification of cooling medium drops. Thereby, cooling medium is easily fed into the medium flow path 4, cooling time is shortened, and cooling efficiency is enhanced.

In the embodiment, the discharge side path 15 on the downstream side of the heat exchanger 20 is constituted so as to return the medium to the cooling medium supply source 10, i.e. so as to circulate cooling medium. Accordingly, deposition of silica, scale, or the like into the medium flow path 4 of the mold 2 or the like contained in cooling medium by gasification of cooling medium decreases as compared with the conventional one constituted in such a manner that cooling medium is not circulated; new cooling medium is supplied and discharged. Thereby, the maintenance or the like of the medium flow path 4 is less frequently required.

In the embodiment, the discharge side path 15 on the downstream side of the heat exchanger 20 is provided with the backflow prevention portion 16 for preventing backflow. Accordingly, when gasified cooling medium is condensed in the heat exchanger 20, the pressure in the paths is more effectively dropped. Thereby, cooling medium is more easily fed into the medium flow path 4, cooling time is shortened, and cooling efficiency is extremely enhanced.

The backflow prevention portion 16 is not limited to the backflow prevention valve as in the figure and can be the opening and closing valve or the like of which opening and closing are controlled by the control portion 22. In such a case, an aspect can be such that, when a pressure drop, associated with condensation in the heat exchanger 20, is detected by the pressure sensor or the like, or a temperature detected by the temperature sensor or the like falls below the predetermined value, the opening and closing valve is opened and liquefied cooling medium is discharged (returned).

As in the above-mentioned embodiment, the constitution can be such that the control portion 22 is provided to control the supply of steam or air and the supply of cooling medium and to supply cooling medium to the medium flow path 4 of the mold 2 after supplying steam or air to the medium flow path 4 of the mold 2. In other words, cooling medium can be supplied to the medium flow path 4 of the mold 2 after the precooling step in which steam or air is supplied to the medium flow path 4 of the mold 2. As constituted above, the mold 2 is precooled by steam or air and cooling medium is more easily fed into the medium flow path 4 thereafter. In other words, the heat of the medium flow path 4 of the mold 2 is absorbed by the medium gasified by mixing the medium with steam or air. The above gasified medium is condensed in the heat exchanger 20 and the pressure drops, thereby more easily feeding cooling medium into the medium flow path 4.

As in the above-mentioned embodiment, the constitution can be such that the control portion 22 is provided to control the supply of steam or air and the supply of cooling medium and to supply steam or air to the medium flow path 4 of the mold 2 after supplying cooling medium to the medium flow path 4 of the mold 2. In other words, after the first cooling step in which cooling medium is supplied to the medium flow path 4 of the mold 2, the second cooling step in which steam or air is supplied to the medium flow path 4 of the mold 2 can be executed. As constituted above, cooling medium remained in the medium flow path 4 of the mold 2 is purged, the heat is absorbed by contacting the medium flow path 4, and the mold 2 is cooled. Thereby, the remaining medium in the medium flow path 4 of the mold 2 decreases and heating is effectively performed.

One example of the mold-cooling system in another embodiment of the present invention and one example of the mold-cooling method executed with the example of the mold-cooling system in another embodiment of the present invention are explained.

FIG. 3 and FIG. 4 illustrate the mold-cooling system in the second embodiment and the mold-cooling method executed with the mold-cooling system in the second embodiment. Differences from the first embodiment are mainly explained and common constitutions are allotted with the same reference numerals and their explanation is omitted or briefly explained. And an explanation of common operations with the example of the operation mentioned above is omitted or briefly explained.

Also in the embodiment, a mold-cooling system 1A is a mold heating-cooling system 1A which performs heating in addition to cooling of the mold 2.

The embodiment mainly differs from the above-mentioned first embodiment in that the steam supply path 18 supplying steam from the steam source 8 is not connected to the supply side path 13, the cooling path 14 communicated with the fluid passage on the low-temperature side of the heat exchanger 20 is not provided with the heat exchanger cooling valve 14a, and the discharge side path 15 on the downstream side of the heat exchanger 20 is not provided with the backflow prevention portion 16.

In the embodiment, the supply amount of cooling medium from the cooling medium supply source 10 is able to be regulated. In the figure, the upstream supply side path 12 connected to a medium feeding side of the cooling medium supply source 10 is provided with a small flow path 12b in a parallel manner; the small flow path 12b is provided with a valve for a small amount of cooling medium 12c which supplies or cuts off cooling medium. In other words, when the cooling medium valve 12a provided for the upstream supply side path 12, i.e. a main path, is closed and the valve for a small amount of cooling medium 12c of the small flow path 12b is opened, a relatively small flow amount of cooling medium is supplied. The valve for a small amount of cooling medium 12c is connected to the control portion 22 through the signal line or the like similar to the other valves and the opening and closing control is performed by the control portion 22.

In place of the above, an aspect can be such that a flow amount control valve or the like capable of controlling an opening degree is provided as the cooling medium valve 12a.

One example of the mold heating-cooling method (the mold-cooling method) as one example of basic operation executed in the mold heating-cooling system 1A in the embodiment constituted as above is explained based on FIG. 4.

Also in a graph of FIG. 4, the horizontal axis is the time axis, the vertical axis is the detection temperature of the temperature sensor 6, and its transition is schematically shown the same as above.

First, the preheating step can be executed and the heating step can be executed in the same manner as above.

After that, the cooling step which cools the mold 2 can be executed.

In the example of the operation, cooling medium is supplied to the medium flow path 4 of the mold 2 without executing the precooling step in which steam or air is supplied to the medium flow path 4 of the mold 2. In other words, when the cooling medium supply pump 11 is activated and the cooling medium valve 12a is opened, cooling medium from the cooling medium supply source 10 is supplied to the medium flow path 4 of the mold 2. The figure shows, the same as above, an example in which the cooling medium supply pump 11 is activated earlier than the opening of the cooling medium valve 12a , considering the rise time or the like.

In the example of the operation, after the first cooling step constituted by the main cooling step, the second cooling step in which a small flow amount of cooling medium and air are intermittently supplied to the medium flow path 4 of the mold 2 is executed. In the example of the operation, the cooling medium valve 12a is closed; the valve for a small amount of cooling medium 12c is intermittently opened; the small flow amount of cooling medium is intermittently supplied to the medium flow path 4 of the mold 2; and after that, the air valve 19a is intermittently opened and air is intermittently supplied to the medium flow path 4 of the mold 2. When the valve for a small amount of cooling medium 12c is closed, the cooling medium supply pump 11 can be stopped. In place of the above aspect, an aspect in the second cooling step can be such that air valve 19a is intermittently opened and air is intermittently supplied to the medium flow path 4 of the mold 2; and after that, the valve for a small amount of cooling medium 12c is intermittently opened and the small flow amount of cooling medium is intermittently supplied to the medium flow path 4 of the mold 2. And further after that, the air valve 19a can be intermittently opened and air can be intermittently supplied to the medium flow path 4 of the mold 2. Or an aspect can be such that the valve for a small amount of cooling medium 12c and the air valve 19a are alternately opened, and the small flow amount of cooling medium and air are alternately supplied to the medium flow path 4 of the mold 2.

In the example of the operation, when the detection value of the temperature sensor 6 as mentioned above falls below the predetermined threshold value (a switching threshold value), the first cooling step is switched into the second cooling step. The setting of the switching threshold value and the execution control of the second cooling step can be appropriately performed in such a manner that, the same as above, cooling medium in the medium flow path 4 is almost discharged (purged) by executing the second cooling step and excessive cooling or the like is not caused; in other words, the temperature does not greatly fall below the target cooling temperature at the end of the cooling step. The above-mentioned switching threshold value can be inputted and set up through the display operation portion 24. In the above-mentioned second cooling step, steam can be supplied in place of or in addition to air as mentioned above.

Also in the example of the operation, the precooling step as mentioned above can be executed.

Also in the example of the operation, after the cooling step, in the mold 2, the mold opening and the demolding of the molded article are appropriately executed, and the heating step and the cooling step are repeatedly executed.

Also in the mold-cooling system 1A (the mold heating-cooling system) in the embodiment and the mold-cooling method (the mold heating-cooling method) which is executed by the above system, an effect substantially similar to the above-mentioned first embodiment and the example of the operation in the first embodiment is obtained.

One example of the mold-cooling system in still another embodiment of the present invention and one example of the mold-cooling method which is executed by the example of the mold-cooling system in still another embodiment of the present invention are explained below.

FIG. 5 illustrates the mold-cooling system in the third embodiment and the mold-cooling method which is executed by the mold-cooling system in the third embodiment.

Differences from the above-mentioned respective embodiments are mainly explained and common constitutions are allotted with the same reference numerals and their explanation is omitted or briefly explained.

Also in the embodiment, a mold-cooling system 1B is a mold heating-cooling system 1B which performs heating in addition to cooling of the mold 2.

In the embodiment, a cooling path 14A which supplies cooling medium to a fluid passage on a low-temperature side of a heat exchanger 20A is not communicated with the cooling medium supply source 10 which supplies cooling medium to the medium flow path 4 of the mold 2 but is communicated with a cooling medium supply source 17 for the heat exchanger 20A. As constituted above, the cooling medium supply source 17 can be a cooling tower or the like installed in the plant or the like and the cooling medium supply source 10 can be the storage portion or the like in which temperature control is not performed, thereby simplifying the constitution of the cooling medium supply source 10.

Also in the mold heating-cooling system 1B in the embodiment, operation (the mold heating-cooling method (the mold-cooling method)) substantially similar to those in the above-mentioned respective embodiments is executed; an effect substantially similar to those in the above-mentioned respective embodiments is obtained.

The heat exchanger 20, 20A is not limited to such an aspect in which cooling is performed by feeding cooling medium into the fluid passage on the low-temperature side; for instance, gasified cooling medium which is fed into the fluid passage on the high-temperature side can be condensed by cooling with a fan or the like, i.e. an air cooling type.

The above-mentioned constitutions, operations, or the like which are different from each other can be appropriately recombined or combined, or appropriately modified as needed.

In the above-mentioned respective embodiments, while an aspect is shown that the discharge side path 15 on the downstream side of the heat exchanger 20, 20A is connected to the medium returning side of the cooling medium supply source 10 and cooling medium is circulated, an aspect can be such that the discharge side path 15 on the downstream side of the heat exchanger 20, 20A is not connected to the medium returning side of the cooling medium supply source 10 and cooling medium is discharged as drain.

In the above-mentioned respective embodiments, the mold heating-cooling system 1, 1A, 1B which performs heating in addition to cooling of the mold 2 is shown but can be the mold-cooling system 1, 1A, 1B which performs cooling of the mold 2. In such a case, a mold-heating system (a mold-heating apparatus) which is controlled separately from the mold-cooling system 1, 1A, 1B and performs heating of the mold 2 can be provided.

In the above-mentioned respective examples of the operation, an example in which, after the first cooling step in which cooling medium is supplied to the medium flow path 4 of the mold 2, the second cooling step in which steam or air is supplied to the medium flow path 4 of the mold 2 is shown; however the second cooling step can be omitted. In such a case, the cooling step can be such that the precooling step as mentioned above is executed and then the main cooling step is executed, or furthermore only the main cooling step is executed. In other words, in order that the pressure is dropped, cooling medium is effectively supplied, and cooling is performed, the discharge side path 15 connected to the outlet 5 side of the medium flow path 4 of the mold 2 can be communicated with the heat exchanger 20, 20A and gasified cooling medium discharged from the medium flow path 4 can be condensed in the heat exchanger 20, 20A.

DESCRIPTION OF THE REFERENCE NUMERAL

1, 1A, 1B mold heating-cooling system (mold-cooling system)

2 mold

3 inlet

4 medium flow path

5 outlet

8 steam source

9 air source

10 cooling medium supply source

12,13 supply side path

15 discharge side path

16 backflow prevention portion

18 steam supply path

19 air supply path

20, 20A heat exchanger

22 control portion

Mold-Cooling System and Mold-Cooling Method

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CPC

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