JP3148689B2 - Foam molding steam supply apparatus and foam molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supply of steam used in a foam molding machine for producing a packaging material made of expanded polystyrene and polyethylene resin, a container for cooling or a construction material, or a base material for an insulated floor. The present invention relates to an apparatus and a foam molding method using the same.

[0002]

2. Description of the Related Art An outline of a foam molding method as a background of the present invention will be described. A mold apparatus used for the foam molding is arranged as shown in a schematic sectional view of FIG. In order to form the cavity 1 for foaming and fusing to form a product, the male convex inside 31 and the female concave inside 21 are opposed to each other, and the concave inside 21 is fixed and cannot move. The convex inside 31 is, as shown in FIG.
Horizontally after the cavity 1 is formed inside
In the right direction), and is movable so that the molded foam can be taken out. The insides 21 and 31 are provided with countless vent holes so that a heating steam described later can pass therethrough.

On the back side of the insides 21, 31, frames 22, 32 and back plates 23, 33 are provided, and a fixed side chamber 2 to which utilities are supplied and a movable side chamber 3 are formed. . In this case, upper ports 24 and 34 are provided above the frames 22 and 32, and lower ports 25 and 35 are provided below the frames 22 and 32. Are connected to steam valves 41 and 51 for supplying steam for heating, and suction ports 42 connected to a decompression tank or a decompression pump are connected to lower ports 25 and 35, respectively.
52 and drain valves 43 and 53 for discharging utilities are connected.

[0004] The steps of manufacturing a foamed molded article using such a mold apparatus include closing the inside mold, filling the expandable raw material beads, foaming and fusion forming the raw material beads, cooling the mold apparatus,
The process includes the steps of opening the inside die, taking out the foamed molded body, and the like. This cycle is repeated as one cycle, and the foamed molded body made of a predetermined expanded polystyrene resin or the like is continuously produced.

[0005] During this cycle, the step of foaming and fusion-forming the expandable raw material beads further includes an exhaust gas for preheating the expandable raw material beads by removing air in the mold apparatus.
It can be divided into a preheating step and a fusion step in which the expanded beads are fused and integrated with each other, and steam having a saturated vapor pressure of an appropriate pressure is used as each heat source.

Here, a conventional example of a piping structure of a steam supply device used for such a purpose will be described with reference to FIG. In this example, the pressure is 5 to 8 k from the main header 6.
g / cm ² steam 6.35 to 7.62 cm
( 2.5 to 3 inch ) pipe 61 and pipes 7 and 8 of the same diameter in the vicinity of the molding machine, and then pressure reducing valves 71 and 81
(CV value of about 30), it is said that the pressure is suitable for foaming and fusing of the foamable raw material beads.
It is reduced to about 1.0 kg / cm ^2, then aperture 2.
The pipes are supplied so as to be supplied to chambers 2 and 3 in the mold apparatus through a flexible hose of about 54 cm ( 1 inch ) .

[0007] The steam capacity required for such a foaming molding machine varies depending on the type of machine, but on average, 3 to 6 kg of steam is included in one cycle of the manufacturing process (required time: 120 seconds to 180 seconds). It is consumed intensively in the foam fusion bonding step of the raw material beads (required time: 20 to 30 seconds). In order to supply steam concentrated in such a short time, the above-mentioned piping structure was used,
The following problems were found.

If the steam supplied from the main header 6 is, for example, a saturated vapor pressure of 5 kg / cm ² , the steam temperature at that time reaches 158 ° C.
When the pressure is to be reduced to, for example, 1.0 kg / cm ² at a stretch by 81, the diameter of the pipe before pressure reduction is 6.35 cm ( 2.5
Inch ) , the pipe after decompression has a diameter of 2.54 cm ( 1
Inch ) , so that the diameter cross-sectional area ratio is 1 ² × 2 / 2.5 ² = 0.32.
Since the reduced-pressure steam has no room for volume expansion, it cannot be reduced to the original temperature of the reduced-pressure saturated steam pressure of 1.0 kg / cm ² , and is sent to the chambers 2 and 3 as superheated steam at a considerably high temperature. Will be. According to actual measurements, this temperature was found to temporarily exceed 140 ° C. near the chamber entrance.

Therefore, in the above-described foam molding method, when the unintended overheated steam of an abnormal temperature is supplied to the mold apparatus, the heat capacity thereof is so large that the entire mold apparatus can be uniformly heated. In addition, there is no capacity, and the non-uniformity consumed in the mold in part of the mold results in temperature distribution, which causes uneven fusion of the raw material beads and causes quality unevenness. Steam generation had to be avoided as much as possible.

In order to solve such a problem, another example of the piping structure shown in FIG. 4 has been devised. Here, a pipe 61 having a diameter of 6.35 to 7.62 cm ( 2.5 to 3 inches ) reaching the main header 6 and pipes 7 and 8 having the same diameter near the molding machine.
Large diameter, for example, 10.16 to 12.7 cm
( 4-5 inches ) Arrange a new pressure reducing valve 62 of diameter,
The steam was once depressurized to an intermediate pressure of ² to 3 kg / cm ^2, and the pressure was renewed by pressure reducing valves 71 and 81 (having a CV value of about 30) provided at the inlet of the mold apparatus.
The pressure is reduced to 1.3 kg / cm ² , and thereafter, the connection to the chambers 2 and 3 via a flexible hose having a diameter of about 1 inch is the same as in the example of FIG.

In this case, a large-diameter pressure reducing valve 62 is used.
The pipes 7 and 8 to the molding machine have little room for volume expansion, and are sent to the molding machine without adjusting the temperature and pressure to an equilibrium state. The situation has not been sufficiently improved.

In recent years, research and development have been carried out in order to promote the fusion of the foamed molded article with low-pressure steam of about 0.5 kg / cm ² in order to remarkably improve the productivity. Therefore, it is necessary to strictly control the steam pressure near the boundary of the fusion starting temperature of the expandable raw material beads, and therefore, it is necessary to eliminate as much as possible the possibility of generating unintended overheated steam. However, there has been a problem that such conventional steam supply apparatus and method cannot sufficiently cope with this.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to cause an abnormal overheating state in a step of reducing the pressure of high-pressure steam supplied from a main header. In addition, the present invention provides a foam molding steam supply device capable of supplying an appropriate amount of steam smoothly. Further, in particular, the present invention provides a foam molding method capable of supplying low-pressure steam while reliably preventing abnormal generation of overheated steam in a fusing step of fusing foamable raw material beads.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a foam molding steam supply device for foam molding for foaming foamable raw material beads filled in a mold. What is claimed is: 1. A steam supply device, comprising: a first pressure reducing valve for primary-pressure reduction of steam ; and a disconnection of pipes connected to the first pressure reducing valve and before and after the first pressure reducing valve.
In area ratio, the diameter cross section is equal to or greater than the pressure reduction ratio of the primary pressure reduction
Product that is consumed in one cycle of the foam molding process.
A storage pipe having a capacity equal to or greater than the amount of the team, and a second pressure for supplying the steam of the storage pipe to the foam molding machine by performing a secondary pressure reduction to a pressure suitable for foaming and fusing the foamable raw material beads. 2 pressure reducing valve.

[0015]

Further, the present invention relates to a foam-forming steam supply apparatus for foam-forming polystyrene or polyethylene-based foamable raw material beads, which has a diameter of 10.16.
5 kg / cm supplied with pipes of cm ( 4 inches ) or less
^A first pressure reducing valve for primary pressure reduction of ^two or more steams to 1.3 to 5.0 kg / cm ² , a storage pipe connected to the first pressure reducing valve and having a diameter of 20.32 cm ( 8 inches ) or more;
The steam of this storage pipe is reduced to 0.3 to 1.3 kg / cm ^2.
And a second pressure reducing valve for performing a secondary pressure reduction.

Further, the foam molding method of the present invention, which has been made to solve the above problem, supplies steam from the foam molding steam supply device to remove air in the mold and to remove the metal from the mold. A foam molding method including an exhaust gas for preheating the expandable raw material beads filled in the mold, a preheating step, and subsequently a steaming step of supplying steam above the fusion temperature of the expandable raw material beads and fusing the raw material beads. And
In the fusing step, the secondary pressure reducing set value of the second pressure reducing valve of the supply device is set to 0.3 to 1.3 kg / cm ^2, and the primary pressure reducing set value of the first pressure reducing valve is set to the secondary pressure reducing value. The steam is supplied at a low pressure value obtained by adding at least 1 kg / cm ² to the next reduced pressure set value. In this foam molding method, the primary pressure reduction set value is set to 3.0 to 5.0 k in the exhausting and preheating steps.
It can be embodied preferably in an embodiment in which the value is in the range of g / cm ² .

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a foam molding steam supply apparatus according to the present invention will be described with reference to FIG. Here, first, the pressure 5 to 5 is applied from the main header 6.
8 kg / cm ² steam 6.35 to 10.16
Although directed to the molding machine near the piping 61 cm (2.5 to 4 inches), in which, the steam pressure 1/4
A first pressure reducing valve 62 for reducing the pressure to a range of about 1.3 to 5.0 kg / cm ² is provided. The pressure reducing valve 62 does not need to have a large diameter as in the conventional example, and may have a diameter of about 5.08 to 7.62 cm ( 2 to 3 inches ) .

A feature of the present invention is that a large-diameter storage pipe 63 is connected to the first pressure reducing valve 62 as in this embodiment. The large-diameter storage pipe 63 is a pipe having a diameter larger than the pipe diameter at the previous stage of the pressure reducing valve 62 and having a capacity capable of storing a certain amount of steam consumed by the mold apparatus. A structure having a diameter cross-sectional area ratio of a primary pressure-reducing ratio or more in a diameter cross-sectional area ratio of pipes before and after the first pressure reducing valve, and having a capacity capable of storing at least an amount of steam consumed in one cycle of the foam molding process. Preferably, there is.

As a preferred example of the large-diameter storage pipe 63, as described above, a diameter of 10.16 cm ( 4 inches ) is used.
In the case where the supplied 5 kg / cm ² or more steam 1.3~5.0kg / cm ² to the primary pressure reduction following pipe, that the diameter of the reservoir pipe to 20.32 cm (8 inches) In order to stably supply steam at a desired pressure, the capacity is preferably set to at least 400 liters. In this case, as the volume of the storage pipe, the volume of the branch pipes 7a and 8a connected to the second pressure reducing valve described later is also totaled, and the steam amount consumed in one cycle of the foam molding process is set as a guide. Is good.

As a further feature, in the present embodiment, the steam in the storage pipe 63 is secondarily reduced to a pressure suitable for heating and fusing the expandable raw material beads, and is supplied to a foam molding machine. And pressure reducing valves 71a, 81a are connected to the storage pipe 63 by branch pipes 7a, 8a having a diameter of about 10.16 cm ( 4 inches ). Instead of a flexible hose having a diameter of about 2.54 cm ( 1 inch ), a flexible type or fixed type connecting pipe having a diameter of about 10.16 cm ( 4 inches ) is used for connection. Then, 1.3 to 5.0 kg / c in the storage pipe 63
The steam whose primary pressure has been reduced to m ² is secondarily reduced to 0.3 to 1.5 kg / cm ² by these second pressure reducing valves 71a and 81a.

According to such an embodiment of the present invention, the steam which has been subjected to the primary depressurization is introduced into the large-diameter storage pipe following the first pressure-reducing valve so as to be able to smoothly expand its volume. However, of course, the occurrence of an abnormal overheating phenomenon even at the second decompression is sufficiently suppressed. Further, in the storage pipe of the embodiment, since the secondary depressurized steam for one cycle of the molding process can be stored, a predetermined amount in which the pressure and the temperature are uniformly adjusted at each foaming operation. Can be continuously supplied to the molding die apparatus after the secondary depressurization, so that there is an advantage that the supplied steam has little variation in quality and can perform uniform foam molding. Further, since there is no risk of overheating steam and the pressure reduction ratio can be set to a large value, there is also obtained an advantage that a foam molding method using low-pressure steam of about 0.5 kg / cm ² can be sufficiently coped with.

Next, one embodiment of the foam molding method of the present invention will be described. In this foam molding method, after filling foamable raw material beads in a mold, steam is supplied to eliminate air in the mold and exhaust gas for preheating the foamable raw material beads filled in the mold, In the foaming method including a preheating step and subsequently supplying steam at or above the fusing temperature of the expandable raw material beads, and a fusing step of fusing the raw material beads, from the above-described foaming steam supply device. It supplies the required steam.

The feature of the foam molding method of the present invention is that the exhaust, preheating and fusing steps
A method in which the primary pressure reducing set value by the first pressure reducing valve is switched to each value as described later, and the primary pressure reducing steam having a different pressure is secondarily reduced and supplied to the mold apparatus. At least in the fusing step, the secondary pressure reducing value of the second pressure reducing valve of the supply device is set to 0.3 to 1.
3 kg / cm ^2, and the primary pressure reducing set value of the first pressure reducing valve is at least 1 kg to the secondary pressure reducing set value.
/ Cm ² is set to a low pressure value and steam is supplied.

The pressure of the supplied steam in the fusion step is conventionally about 0.7 to 1.3 kg / cm ² , but in the present invention, it is 0.3 to 1.3 kg / cm ² , more preferably, about 0.3 to 1.3 kg / cm ² . It is characterized by using low-pressure steam of 0.3 to 0.7 kg / cm ² . By using such low-pressure steam, it is possible to keep the foam molded body and the entire mold apparatus at a relatively low temperature without overheating, while being sufficient to fuse the raw material beads, and as a result, the cooling step It is possible to greatly shorten the entire process by 30% or more.

In this case, the secondary pressure reduction set value is set to 0.3 to 0.1.
7 kg / cm ^2, and the primary pressure reducing set value of the first pressure reducing valve is changed to the secondary pressure reducing set value by 1.0 to 2.0 kg.
More preferably, it is set to a low pressure value obtained by adding a differential pressure of / cm ² . In this case, as a result, the pressure value of the primary pressure reduction set value is set in the range of 1.3 to 2.7 kg / cm ² .

[0027] In the foam molding method of the present invention, the primary pressure reduction set value of the first pressure reduction valve may be a low pressure obtained by adding at least a differential pressure of 1.0 kg / cm ^{2 to} the secondary pressure reduction set value, or preferably, Since the pressure is set to a low pressure value obtained by adding a differential pressure of 1.0 to 2.0 kg / cm ^2, the pressure reduction ratio by the second pressure reducing valve is relatively small, so that there is no possibility of generating overheated steam, and The advantage that accurate pressure control becomes possible is obtained.

Further, according to the present invention, in the fusing step, the set value of the secondary pressure reduction and the set value of the primary pressure reduction are set to values within the specific ranges as described above, and in the exhausting and preheating steps which are the preceding steps. Also, the primary pressure reduction set value is set to 3.
The embodiment can be preferably embodied in a mode in which the pressure is set to 0 to 5.0 kg / cm ² .

In this case, the steam supplied to the exhausting and preheating process excludes the air inside the mold and includes the foaming raw material beads filled in the mold and the heavy mold itself. Therefore, in order to supply a considerable amount of steam in a short time, the primary decompression set value is set to 1 in the case of the above-described welding step in order to supply a considerable amount of steam in a short time. By setting it to 3.0 to 5.0 kg / cm ^{2, which} is higher than 3 to 2.7 kg / cm ² , a sufficient amount of steam can be secured.

[0030]

As described above, the apparatus for supplying steam for foam molding of the present invention is configured as described above. Therefore, in the step of reducing the pressure of the high-pressure steam supplied from the main header,
Since an abnormal overheating state is not caused, uneven foaming and fusion of the foamed molded article are suppressed, and a high quality product can be obtained. Further, since a predetermined amount of steam whose pressure and temperature are uniformly adjusted can be supplied, this also greatly contributes to the production of a stable foam molded article.

Further, according to the foam molding method of the present invention, in the fusing step, a pressure of 0.3 to 1.3 kg lower than that of the conventional method is used.
/ Cm ² region can be supplied stably and there is also an excellent effect that productivity can be improved. Therefore, the present invention
Some of the conventional steam-supplying apparatuses and foam-forming methods which solve the conventional problems have extremely large industrial value.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an arrangement of a steam supply pipe for describing an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a main part of a foam molding machine.

FIG. 3 is a schematic view showing the arrangement of a conventional steam supply pipe.

FIG. 4 is a schematic view of another conventional steam supply pipe arrangement.

[Explanation of symbols]

 Reference Signs List 1 cavity 2, 3 chamber 6 main header 7a, 8a branch pipe 41, 51 steam valve 42, 52 suction valve 43, 53 drain valve 61 pipe 62 first pressure reducing valve 63 storage pipe 71, 71a, 81, 81a second Pressure reducing valves 72a, 82a Connecting pipe.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 44/00-44/60 B29C 67/20

Claims (4)

(57) [Claims] An apparatus for supplying foaming steam for foaming foamable raw material beads filled in a mold, comprising: a first pressure reducing valve for temporarily reducing the pressure of steam;
Connected to the first pressure reducing valve and arranged before and after the first pressure reducing valve.
In the pipe diameter cross-sectional area ratio, the pressure reduction ratio of the primary pressure reduction
With a cross-sectional area of
At least a storage pipe having a capacity equal to or greater than the amount of steam to be consumed . Further, the steam in the storage pipe is secondarily reduced to a pressure suitable for foaming and fusing of the expandable raw material beads and supplied to the foam molding machine. And a second pressure reducing valve for supplying the steam for foam molding. 2. A foaming steam supply device for foaming polystyrene or polyethylene-based foamable raw material beads, which is supplied by a pipe having a diameter of 10.16 cm (4 inches) or less and 5 kg / cm ² or more. A first pressure reducing valve for primarily reducing the pressure of steam to 1.3 to 5.0 kg / cm ² , and a diameter of 20.32c connected to the first pressure reducing valve
m (8 inches) or more, and a second decompression of the steam in this storage pipe to 0.3 to 1.3 kg / cm ² .
The steam supply device for foam molding according to claim 1, further comprising a pressure reducing valve. 3. A supply steam from the supply device for foam molding steam according to claim 1 or 2, pre-heating the foamable ingredient beads filled into the mold while eliminating the air in the mold An evacuation, a foaming method including a preheating step followed by supplying steam at or above a fusion temperature of the expandable raw material beads, and a fusion step of fusing the raw material beads. The secondary pressure reducing set value of the second pressure reducing valve of the device is set to 0.3 to 1.3 kg / cm ^2, and the primary pressure reducing set value of the first pressure reducing valve is set to at least 1 kg / cm A foam molding method, characterized in that steam is supplied at a low pressure value to which cm ² has been added. Wherein said exhaust, in the preheating step, foam molding method according to claim 3, value ranges of the primary vacuum setpoint of 3.0~5.0kg / cm ^2.