JP3756846B2 - Molding system for polystyrene foam products - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foam molding system suitable for molding a foamed polystyrene product.
[0002]
[Prior art]
Foamed resin products such as storage boxes for fresh fish and processed products and block-shaped products are generally made of polystyrene foam. In general, such polystyrene products are filled with pre-foamed and dried beads in a mold cavity composed of a moving side and a stationary side, and a heated fluid is pressed into the cavity in this state to form a product. The foamed particles are heat-sealed from the inside to the outside to form a predetermined shape, and then cooled to open the mold and release the product.
[0003]
In this process, conventionally, a high pressure (7 kg / cm ² G) steam generated by a general-purpose boiler as a heating fluid is pressure (0.8 kg / cm 2) corresponding to a temperature suitable for molding (about 118 ° C.) with a pressure reducing valve. ² G), the mold constituting the cavity is provided with slit holes at many locations so as to penetrate the inside and outside, and the vapor is passed through the slit holes with the primary foam beads filled in the mold. It was sprayed into the cavity, and immediately after that, cooling water was supplied to the mold and cooled for mold release and product removal.
[0004]
However, since the steam temperature remains high only by reducing the pressure of the high-pressure steam, it is unstable in the superheated steam state. For this reason, the superheated steam higher than the fusing temperature makes the fusing of the expanded polystyrene particles unstable, and the high temperature of the superheated steam often causes the polystyrene small pieces to heat fusing in the slit, causing clogging and clogging of the slit. It was. For this reason, combined with difficulty in controlling the fusing temperature, the molding efficiency is lowered, and the cost is adversely affected.
[0005]
In addition, the conventional cooling water injection is alternately performed because of steam injection and mold release during heating, and the thermal efficiency is poor because the molded product is indirectly cooled with the so-called “Tanma” in the mold. A large amount of cooling water is required, and because the heating steam and cooling water are mixed during cooling, waste heat recovery and cooling water recovery cannot be performed, and a large amount of hot water is generated as waste water, which makes it difficult to process. was there.
[0006]
Further, conventionally, in order to release the molded product from the mold, a number of extrusion pins are mechanically inserted into and removed from the mold. For this reason, it becomes difficult to seal the sliding portion, and therefore, it is obstructed to hermetically seal the inside of the cavity, and since it is necessary to remove a large number of release pins, it takes a lot of time and labor to change the mold. There was a problem.
[0007]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems, and the object of the present invention is to avoid clogging of the slits, improve the product yield, and use cooling water for mold release. The object of the present invention is to provide a new foamed polystyrene molding system that can improve the molding cycle as a whole, save significant energy, and simplify equipment.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention fills a foaming raw material in a mold having a fixed mold and a movable mold constituting a cavity, heats it with steam in a mold-clamped state, and then performs fusion molding, and then cools, In a molding system for releasing and releasing mold clamping, a thermocompressor for generating low-pressure saturated steam by controlling the pressure of high-pressure steam under reduced pressure in a system connecting a steam supply source and a mold, and generated by the thermocompressor A steam storage tank that stores the low-pressure saturated steam and supplies it to the mold, and a vacuum tank that is connected to the suction side of the thermocompressor to store the vacuum generated when the steam is decompressed and to allow the vacuum to act through the mold The high-pressure steam from the steam source is passed through a thermo compressor, the steam drain is decompressed and mixed with the re-flashed steam, and the low-pressure saturated steam obtained by mixing with the steam is stored in the steam storage tank. In one side of supplying the pressure saturated vapor to the mold in the heat fusion process, in the cooling process after molding, the vacuum in the vacuum chamber is applied to the molded product in the mold, and is attached to the molded product. The feature is that the molded product is cooled by evaporating the condensed water in vacuum.
[0009]
Preferably, at least two stages of the thermocompressor are arranged in series, and the discharge side of the upstream thermocompressor is connected to the suction side of the downstream thermocompressor.
[0010]
The present invention includes a configuration including a vacuum pump for generating a vacuum in a vacuum chamber at the start of operation.
In addition, the present invention includes a configuration in which an air tank communicating with the cavity is provided behind the mold, and the molded product is released from the air tank by injecting air pressure into the cavity.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 to 4 show an embodiment of a molding system for a foamed polystyrene product according to the present invention. Reference numeral 1 denotes a mold for foamed polystyrene product including a fixed mold 1a and a movable mold 1b. When the movable mold 1b is brought into and out of contact with the fixed mold 1a by a back mold clamping device 1c, the mold is clamped. A plurality of shaped product shaped cavities 1e are defined.
[0012]
The fixed mold 1a is provided with a foam raw material (foam bead) filling pipe 1d leading to the cavity 1e, and a supply pipe 102 is connected to the foam raw material filling pipe 1d via a raw material hopper 100 and a shutter 101. At the same time, a compressed air supply system for press-fitting the foaming raw material fed into the foaming raw material filling pipe 1d into the cavity 1e is connected.
[0013]
A plurality of cavities 1e are formed in one mold 1. As shown in FIG. 4, steam for heating is applied to the mold surfaces 10a and 10b of the fixed mold 1a and the movable mold 1b facing the cavity 1e. An infinite number of fine slits 105 are arranged to be introduced into the cavity c and to apply a vacuum to the cavity 1e during cooling.
[0014]
In FIG. 1, A is an apparatus for vacuum forming which is a feature of the present invention, and is produced by a thermocompressor 2 for producing a vacuum at the same time as obtaining a low-pressure saturated steam by depressurizing high-pressure steam, and generated by the thermocompressor 2. For forming low pressure saturated steam generated by the vacuum chamber 3 and the thermocompressor 2 which is a means for storing the collected vacuum and working the vacuum in the mold to vaporize and recover the condensed water adhering to the molded product. And a steam storage tank 4 which is stably stored as steam and supplied to the mold 1.
[0015]
FIG. 2 shows details of the vacuum forming apparatus A. The thermocompressor 2 includes a high-pressure steam introduction section 20, a nozzle section 21, a steam jet ejector having a suction section 23 and a low-pressure steam discharge section 22 communicating with each other. It is made up of.
The thermocompressor 2 may be a single one as long as it can obtain a high vacuum, for example, about -600 mmHg, but a plurality of thermocompressors are usually used in series. In this example, there are two stages, and the diffuser 22 of the first thermocompressor 2a is connected to the suction portion 23 of the second thermocompressor 2b by a connecting pipe 24.
[0016]
A high-pressure steam pipe 6 from a steam boiler B as a high-pressure steam supply source is connected to the high-pressure steam introduction parts 20 and 20 of the first and second thermocompressors 2a and 2b, for example, 7 kg / cm ² G high-pressure steam. Is to be guided.
The suction part 23 of the first thermocompressor 2 a is connected to the exhaust part (suction part) 30 of the vacuum chamber 3. The discharge port of the diffuser 22 of the second thermo compressor 2 b is connected to the low pressure steam intake unit 40 of the steam storage tank 4.
[0017]
The steam storage tank 4 is a pressure tank made with a predetermined volume so as to store a low-pressure saturated steam generated by the thermocompressor 2 such as 0.8 kg / cm ² G in a sufficient amount, and a low-pressure saturated steam take-out section is provided at the upper part. 41 is provided, and a forming steam supply pipe 7 leading to the fixed mold 1a and the movable mold 1b is connected thereto. The forming steam supply pipe 7 includes a switching valve 71 and operates in response to a forming signal so as to introduce low-pressure saturated steam from the headers of the fixed mold 1a and the movable mold 1b into the cavity 1e through the slits 105 ′ and 105 ′. It has become.
[0018]
As shown in FIG. 2, the steam storage tank 4 is provided with a control port 42 at another location, and a controller 44 attached thereto is connected to the control unit 6 of the control valve 6 a of the high-pressure steam pipe 6 by the control system 43. The control valve 6a is opened and closed according to the pressure of the low-pressure saturated steam to store the low-pressure saturated steam at a predetermined pressure. For example, when the pressure of the low-pressure saturated steam in the steam storage tank 4 reaches 0.75 kg / cm ² G, the control valve 6a is opened to continuously supply high-pressure steam to the thermocompressor 2, and the low-pressure in the steam storage tank 4 When the saturated steam pressure reaches 0.85 kg / cm ² G, the control valve 6a is closed to stop the supply of high-pressure steam.
[0019]
The high-pressure steam pipe 6 has a drain pipe 60 having a steam trap 601, and the drain pipe 60 is connected to a steam return pipe 9 that leads to a drain intake portion 31 of the vacuum chamber 3 described later.
Further, a drain portion 45 is provided at the lower portion of the steam storage tank 4, and a drain pipe 46 having a steam trap 460 is connected to the drain section 45, and the drain pipe 46 is connected to the drain pipe 60.
47 is a pressure gauge provided in the steam storage tank 4, and 48 is a warm clock.
[0020]
The vacuum chamber 3 is configured as a pressure tank, and as described above, in addition to the exhaust part 30 connected to the suction part 23 of the thermo compressor 2a by piping, the drain intake part 31 connected to the drain pipe 60, and the suction part 32. Is provided. A vacuum suction pipe 8 from a vacuum suction header (not shown) of the fixed mold 1a and the movable mold 1b is connected to the suction section 32 as shown in FIG.
[0021]
As shown in FIG. 1, a steam return pipe 9 having a steam trap 90 is connected to the vacuum suction pipe 8, and the steam return pipe 9 is connected to the vacuum chamber 3.
Inside the vacuum chamber 3, as shown in FIG. 2, a spray nozzle 36 connected to the drain intake unit 31 by a conduit is arranged, and by this, the condensed water is sprayed and suction from the thermocompressor 2 acting on the suction unit 30. Re-evaporation is performed by (vacuum).
The vacuum suction pipe 8 and the steam return pipe 9 are provided with switching valves 81 and 91, respectively, as shown in FIG. The switching valve 81 is normally closed, and the switching valve 91 is normally open.
[0022]
The vacuum chamber 3 also has a connection 37 to the external vacuum pump 5. The vacuum pump 5 is not necessarily required, but the balance between the generation of vacuum at the start of operation and the amount of steam to be introduced into the thermocompressor 2 during operation (the amount of steam necessary for molding) is to be generated. Preliminarily used together to improve. 38 is a pressure gauge and 39 is a thermometer.
[0023]
The fixed mold 1a does not have an extruding extrusion pin protruding into the mold through the foaming raw material filling pipe 1d as in the prior art, and instead has an air tank 12 that communicates with the cavity through the foaming raw material filling pipe 1d. The compressed air supply system 11 is connected to this via an on-off valve 120, and the on-off valve 120 is opened at the time of mold release, so that the molded product attached to the fixed mold 1a is pushed out by air pressure. Yes. If necessary, it is preferable to give a draft of about 1/50 to the mold surface 10a of the mold. In addition, the air tank 12 may have a common large volume or may be used for filling the foaming raw material.
[0024]
In practice, a plurality of molding systems C including the mold 1, the molding steam supply pipe 7, the vacuum suction pipe 8, and the steam return pipe 9 are arranged as shown in FIG. Device A is used.
[0025]
[Effect of the embodiment]
The operation according to the embodiment will be described. The fixed mold 1a and the movable mold 1b are closed and clamped by the mold clamping device 1c, and the primary foaming raw material is filled into the cavity 1e from the raw material hopper 100 through the foaming raw material filling pipe 1d. Then, by supplying steam from the molding steam supply pipe 6 through the slit 105 of the fixed mold 1a and the movable mold 1b, secondary foaming and fusion are performed, and then cooling is performed for mold release. The basic process of separating the movable mold 1b from the mold is the same as the conventional process.
[0026]
In the present invention, the vacuum pump 5 is driven during operation, and the inside of the vacuum chamber 3 is depressurized to be in a vacuum state. At this time, the switching valve 90 of the steam return pipe 9 is closed so that no vacuum acts on the mold 1. In the vacuum chamber 3, the steam drain (saturation temperature water) already used for molding is stored. When a predetermined degree of vacuum is reached, the vacuum pump 5 may stop operating.
[0027]
If high pressure steam, for example, 7 kg / cm ² G is supplied from the steam supply source B such as a boiler to the high pressure steam pipe 6 in this state, the high pressure steam is supplied to the first and second thermo compressors 2 a and 2 b of the thermo compressor 2. The gas is introduced into each high-pressure steam introduction unit 20, 20, throttled by the nozzles 21, 21, and discharged from the low-pressure steam discharge units 22, 22.
[0028]
Since the nozzles 21, 21 have intersecting suction portions 23, 23, the internal air of the vacuum chamber 3 is sucked into the suction portion 23 of the first thermo compressor 2 a and passes through the second thermo compressor 2 b from the low pressure steam discharge portion 22. It is mixed with steam and sucked into the suction part 23 of the second thermocompressor 2b, and introduced into the low pressure steam intake part 40 of the steam storage tank 4 from the low pressure steam discharge part 22 of the second thermocompressor 2b.
[0029]
That is, a vacuum is generated by the thermocompressor 2, and the condensed water in the vacuum chamber 3 is reflashed to generate steam. Pressure steam 7 kg / cm ² G is joined is depressurized to 0.8 kg / cm ² G, as the saturated vapor steam reduced in pressure and reduction temperature control styrofoam fusion optimum temperature, of being stored in the steam storage tank 4. The operation of the thermocompressor 2 is continuously performed during operation.
[0030]
In the present invention, the foaming polystyrene fusion temperature is controlled depending on the relationship between the saturated steam temperature and the pressure. Even if it is difficult to control the steam temperature (the foaming polystyrene fusion temperature), the saturation steam pressure is controlled relatively easily. Therefore, the high-pressure steam from the boiler is necessary for stable foam polystyrene fusion by reducing the saturated steam pressure to 0.8 kg / cm ² G corresponding to the optimum temperature (about 118 to 120 ° C) for the polystyrene foam molding. The temperature can be obtained. At the same time, due to the suction action of the thermocompressor 2, a high vacuum state of about −600 mmHg is continuously maintained in the vacuum chamber 3.
[0031]
The saturated steam depressurized to 0.8 kg / cm ² G in the steam storage tank 4 is always automatically controlled by the control system 43, and the fixed mold 1a and the movable mold 1b are closed and clamped by the mold clamping device 1c, and the foaming material Is filled into the cavity 1e from the raw material hopper 100 through the foamed raw material filling pipe 1d, the switching valves 71 and 71 are opened according to the sequence, and the low-pressure saturated steam passes through the molding steam supply pipe 7 through the slits of the fixed mold 1a and the movable mold 1b. 105 'is introduced into the cavity 1e.
This low-pressure saturated steam is not superheated steam, but steam that has been depressurized and reduced in temperature in response to the optimum temperature for fusing styrene foam. By heating the foaming raw material with such saturated steam, the necessary heat quantity is stabilized by the latent heat of condensation of the steam. Can be given. For this reason, the secondary foaming and the molding are performed under the condition that the fusion of the polystyrene foam pieces in the slit of the mold surface is avoided and the slit closing trouble is accurately avoided. The used saturated steam is collected in the vacuum chamber 3 by the steam return pipe 9.
[0032]
Next, when the switching valves 71 and 71 are closed and the supply of the forming steam from the steam storage tank 4 to the mold 1 is stopped, the switching valves 81 and 81 of the vacuum suction pipe 8 are opened. Thereby, the vacuum chamber 3 communicates with the cavity 1e of the mold 1, and the cavity 1e is decompressed. Condensed water of about 120 ° C. adheres to the surface of the molded product in the cavity, but the condensed water is suddenly vaporized and re-evaporated by reducing the pressure to about 525 mmHg by the action of the vacuum, evaporating. Deprives the surface of the molded product as latent heat.
Thereby, the molded product is directly cooled to about 90 ° C. suitable for mold release. Therefore, it is extremely effective as compared with the conventional indirect cooling of the mold by the cooling water, and almost no facilities such as cooling water, piping for supplying and discharging the cooling water, and a pump are required. Of course, depending on the case, water for evaporation may be sprayed into the cavity.
[0033]
Next, the switching valves 81, 81 of the vacuum suction pipe 8 are closed, and the vacuum tank 3 and the cavity 1 e of the mold 1 are communicated by the steam return pipe 9 by the switch valves 91, 91 of the steam return pipe 9.
Thus, the molding steam re-evaporated from the surface of the molded product of the steam drain used for molding is condensed water (saturated temperature water) and introduced into the vacuum chamber 3 from the steam return pipe 9, and the spray nozzle inside. 36 is sprayed and stored. A vapor drain used for molding is introduced into the vacuum chamber 3.
[0034]
These condensed waters are reflashed by suction (vacuum) from the thermocompressor 2 as described above to become steam, mixed with the steam passing through the thermocompressor 2 and again become low-pressure saturated steam and stored in the steam storage tank 4. It is used as a heating medium for fusing. Therefore, a great energy saving effect can be obtained.
[0035]
Thus, when the molded product is cooled, the fixed mold 1a and the movable mold 1b are separated from each other, and at this time, the present invention opens the on-off valves 120 and opens the mold surfaces via the respective air tanks 12. Blow air through the slit. Thus, the molded product can be easily released.
One cycle is completed as described above, and molding is performed by repeating similar cycles.
[0036]
The actions of the present invention are summarized as follows.
1) Utilizing the thermocompressor 2, the superheated steam is converted into saturated steam to obtain steam that has been depressurized and reduced to the optimum temperature for fusing polystyrene foam. That is, the steam drain (saturation temperature water) used for the polystyrene foam molding is stored in the vacuum chamber 3, and the high pressure steam pipe 6 generated in the boiler and the thermo compressor 2 are connected thereto. By generating a vacuum in the thermocompressor 2, the condensed water is reflashed to generate steam. The high-pressure steam coming from the boiler is decompressed, joined, and stored in the steam storage tank 4 as steam whose temperature is controlled to be reduced. From this, the following features are exhibited.
[0037]
{Circle around (1)} The steam pressure is constant at the saturation temperature (= pressure) because the steam drain is reflashed. That is, the control is performed by replacing the temperature control with the saturated steam pressure. Therefore, the pressure and temperature of the forming steam are stabilized, and the fusion of styrene due to the heating of the slit and the clogging caused thereby are prevented.
[0038]
(2) Reuse the energy when the high-pressure steam is expanded adiabatically to reuse the steam reflashed from the steam drain, that is, re-evaporate the steam condensate used in the mold and re-mold the mold. Because you work in the house, you can save a lot of energy.
[0039]
2) Along with the generation of stable low-pressure steam by the thermocompressor 2, this energy is used to generate a vacuum, and this is utilized effectively, so the following characteristics are exhibited.
(1) In the past, the cooling required for mold release was dependent on indirect cooling via a mold, but when the polystyrene foam was heated with saturated steam and the molding was completed, By applying the vacuum generated by the thermocompressor 2 to the condensate, it is possible to directly cool the formed work by abrupt vaporization by reducing the pressure of the condensate without using a dedicated vacuum pump.
[0040]
(2) In the conventional system, since the steam drain and the cooling water are mixed, it is difficult to recover the waste heat from the steam drain and the huge amount of cooling water. Since it is left to the vacuum evaporation of moisture adhering to the molded product, cooling of the mold using cooling water is not necessary, and waste heat can be recovered from the steam drain, simplifying the equipment and greatly saving energy Can be achieved. Further, since control in a narrow temperature range of about 90 ° C. to 120 ° C. is sufficient, the molding cycle time can be shortened and the efficiency can be improved.
[0041]
【The invention's effect】
According to the first aspect of the present invention described above, the following excellent effects can be obtained.
(1) The high pressure steam is depressurized and regulated through the thermocompressor 2 to obtain low pressure saturated steam at the optimum temperature for styrene foam fusion, which is stored in the steam storage tank 4 and supplied to the mold 1. Troubles can be avoided, the amount of molding steam used can be reduced, the temperature and pressure can be stabilized, and the product yield can be improved.
[0042]
(2) A vacuum is obtained by utilizing the energy of the thermocompressor 2 that reduces the high-pressure steam to a saturated steam pressure corresponding to the optimum temperature (approx. 118 ° C) for polystyrene foam molding, and this is used to cool the molded product. Thus, the steam condensate used in the mold is guided to the vacuum chamber 3 and re-evaporated by the thermocompressor 2 and again introduced into the mold as molding steam, so that a great energy saving can be achieved.
[0043]
(3) Since the vacuum generated simultaneously with the generation of the low-pressure saturated steam of the thermocompressor 2 is used for cooling for mold release and the molded product is directly cooled using latent heat of vaporization, great energy saving can be achieved.
(4) The thermocompressor 2 produces steam depressurized and reduced to the optimum temperature for styrene foam fusion, and at the same time, a vacuum is obtained. This vacuum is used for depressurization and cooling in the mold. The system becomes unnecessary, and waste heat can be recovered from the steam drain, and cooling water is not particularly required.
[0044]
According to claim 2, since the thermocompressor 2 is installed in a plurality of stages in series, a high vacuum can be reliably obtained, and at the same time, a low-pressure saturated steam optimal for foamed polystyrene can be stably obtained. Excellent effect is obtained.
[0045]
According to the third aspect of the present invention, the molded product is released with compressed air instead of the release pin, so that the vacuum is not hindered and the die replacement time can be simplified and shortened. The excellent effect is obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing one embodiment of a molding system for a foamed polystyrene product according to the present invention.
FIG. 2 is an explanatory diagram showing a main part of the system of the present invention.
FIG. 3 is a side view showing the arrangement of the system of the present invention.
FIG. 4 is a cross-sectional view schematically showing an enlarged mold part of a mold according to the present invention.
[Explanation of symbols]
1 Mold 1a Fixed mold 1b Moving mold 2 Thermocompressor 3 Vacuum tank 4 Steam storage tank

Claims (3)

A mold 1 having a fixed mold 1a and a movable mold 1b constituting a cavity is filled with a foaming raw material, heated in a mold-clamped state using steam and fusion-molded, then cooled, and mold-clamping release / release is performed. In the molding system to do
In the system connecting the steam supply source and the mold 1, the thermocompressor 2 for controlling the pressure of the high-pressure steam under reduced pressure to generate the low-pressure saturated steam, and storing the low-pressure saturated steam generated by the thermocompressor 2 in the mold 1 A steam storage tank 4 to be supplied and a vacuum tank 3 connected to the suction side of the thermocompressor 2 to store the vacuum generated when the steam is depressurized and to act on the vacuum through the mold are provided, and a high pressure from the steam supply source is provided. The low-pressure saturated steam obtained by mixing the steam through the thermocompressor 2 and depressurizing the steam drain and mixing with the re-flashed steam is stored in the steam storage tank 4, and the low-pressure saturated steam is supplied to the mold 1 in the heat fusion process 1 On the other hand, in the cooling process after molding, the vacuum in the vacuum chamber 3 is applied to the molded product in the mold, so that the condensed water adhering to the molded product is vacuum evaporated to cool the molded product. Styrofoam product forming system, characterized in that had Unishi. The molding system of a polystyrene foam product according to claim 1, wherein the thermocompressors 2 are arranged in series in at least two stages, and the discharge side 21 of the upstream thermocompressor 2a is connected to the suction side 20 of the downstream thermocompressor 2b. 2. The foamed polystyrene product according to claim 1, wherein an air tank 12 communicating with the cavity is provided behind the mold 1, and the molded product is released by injecting the air pressure of the air tank 12 into the cavity. Molding system.

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