JPS62261424A - Molding of synthetic resin expandable particle and filling gun device or the same particle - Google Patents

Abstract

PURPOSE:To reduce the generating rate of faulty molded form due to the excess or shortage of filling of expandable particles by a method wherein the supply of the expandable particles into a cavity is stopped when the detecting pressure of a pressure detecting device becomes higher than the internal pressure of the cavity by a predetermined value. CONSTITUTION:When expandable particles in a hopper 1 are filled gradually into a cavity 21 in a mold through a filling gun device D, the pressure of the inlet port of the filling port 22 of the cavity becomes high gradually. When said pressure has become higher than a pressure P1 in the mold, which is generated by pressurizing gas, by 0.5kg/cm<2>, for example, the filling port 22 of the cavity is closed by the operation of a pressure switch PS and the supply of the expandable particles into the mold can be stopped perfectly. In this case, the operating pressure of the pressure switch PS is set in accordance with the kind of the expandable particles, the size and shape of an expanded molded form to be molded or the like. According to this method, the expandable particles are filled into the cavity of the mold without excess or shortage when the supply of the expandable particles is stopped. In case a filling tube is made by a double tube structure, the expandable particles, which remain in the tip end section of the filling tube, may be blown back.

Description

DETAILED DESCRIPTION OF THE INVENTION (&) OBJECTS OF THE INVENTION The present invention relates to a method for molding foamed synthetic resin particles and a filling gun device used in the molding method.

(Industrial Application Field) The molding method and filling gun device of the present invention can be advantageously used to produce molded thermoplastic synthetic resin foam products used for various containers, heat insulating materials, cushioning materials, etc. Ru.

(Prior art) Conventionally, when filling foam particles into a mold in foam molding of synthetic resin foam particles, the volume of foam particles to be filled has been measured in advance, and the measured amount has been filled in the entire mold before filling. A method of closing the gun was used.

To measure the foamed particles to be filled, a method has been used in which the total amount is measured using a patch method using a measuring tank, or a method in which υ is measured by the number of counts in a chamber of a rotary set.

However, this method of weighing a certain amount of foamed particles, filling the entire amount into the mold, and then closing the filling gun is difficult because the density of foamed particles generally varies from particle to particle (i.e., synthetic resin Expanded particles have a density variation of about 10 to 20%).

It is easy to overfill or underfill, resulting in a high incidence of defective molded products.

In other words, in the conventional method described above, the pressure inside the mold is generally first set in accordance with the average density of the product to be molded, and molding is performed at that pressure. Since the compressive stress is large and the degree of compression is small, the volume under compression in the mold becomes large, and the filling gun does not close when the mold is filled to more than the cavity volume. If the mouth part is severely overfilled, the particles will not be sufficiently fused, and the molded product will easily crack into a mouth shape. Conversely, if particles have a density lower than the average density, the volume under compression in the mold will be small, and the filling gun will be closed before the cavity volume of the mold is fully filled. The mouth part is prone to molded parts with insufficient filling.

(Problems to be Solved by the Invention) The present invention is capable of easily and automatically filling a mold with foamed particles without defects even if the density of the foamed particles varies. The object of the present invention is to provide a method for molding foamed synthetic resin particles that can reduce the incidence of defective molded products due to excess or deficiency of molded products, and a filling gun device suitable for use in the molding method.

(b) Structure of the Invention (Means for Solving the Problems) As a result of various studies to solve the above-mentioned problems, the present inventors have developed a pressure detection device at the inlet of the mold cavity filling port. If the supply of foamed particles into the cavity is stopped when the pressure detected by the pressure detection device becomes higher than the pressure inside the cavity by a predetermined pressure, filling of the foamed particles can be easily and automatically overfilled. They discovered that the present invention can be carried out without any shortage.

The method for molding foamed synthetic resin particles of the present invention involves supplying and filling the foamed synthetic resin particles into the cavity of a mold whose pressure is increased with pressurized gas while compressing it using pressurized gas that is higher than the pressure inside the mold. In a method of forming a molded foamed product by fusing foamed particles by steam heating, a pressure detection device is provided at the inlet of a cavity filling port of the mold, and the detected pressure of the pressure detection device is set to a predetermined value higher than the cavity internal pressure. This method is characterized in that the supply of expanded particles into the cavity is stopped when the pressure increases by .

The method for molding foamed synthetic resin particles of the present invention is as follows:
Although this can be carried out using a variety of foamed synthetic resin particle filling gun devices, a particularly preferred filling gun device has a main hole communicating with the filling port of the mold cavity, a transfer conduit for the foamed synthetic resin particles. A filling gun device having a plunger capable of closing a cavity filling port, the gap between the inner pipe and the outer pipe of the filling pipe having a double pipe structure communicating with the inlet portion of the cavity filling port, The present invention is characterized in that a pressure detection device is installed in the gap between the inner and outer tubes of the filling tube having the double tube structure.

In addition, a main hole communicating with the cavity filling port of the mold, a branch hole communicating with the synthetic resin foam particle transfer pipe, a filling pipe with a double pipe structure connecting the cavity filling port and the main hole,
and a filling gun device having a plunger capable of closing the cavity filling port, the gap between the inner pipe and the outer pipe of the filling pipe having a double pipe structure being communicated with the inlet portion of the cavity filling port. has been known in the past (see Japanese Utility Model Publication No. 51-8946), but the reason why the filling tube in this known filling gun device was made into a double pipe structure and the gap was made to communicate with the inlet of the filling port was as follows. By blowing air blown into the air inlet provided in the gap into the inlet of the filling port, excess foamed particles remaining at the tip of the filling tube after filling are blown back. Therefore, this known filling gun device does not have a pressure detection device attached to the gap between the inner and outer double pipe structure, and is completely different from the filling gun device of the present invention in this point.

In the present invention, various devices can be used as the pressure detection device at the entrance of the cavity filling port that is attached to the gap between the filling pipes having the inner and outer double pipe structure, and the device that stops the supply of foam particles based on the detected pressure. It is generally desirable to use a pressure switch that is activated by a set pressure. In other words, if a pressure switch is provided in the gap that is activated when a predetermined pressure is reached, the pressure switch can easily detect the pressure at the inlet of the filling port, so that the detected pressure will not reach the predetermined pressure. Once reached, a pressure switch can be activated immediately to stop the supply of foam particles. The set pressure of the pressure switch is 0.2 to 1 whisper 2,
Preferably, the pressure is 0.4 to 0.7 ktY12 higher. If the set pressure is too close to the mold internal pressure, malfunctions are likely to occur, and if it is too high compared to the mold internal pressure, there will be a delay in stopping the supply of foam particles, resulting in overfilling. .

In addition, in the present invention, to stop the supply of foamed particles into the mold by detecting pressure, the plunger is actuated by the detection pressure to close the filling port of the cavity of the mold, and at the same time, the monotor of the rotary supply device for supplying foamed particles is activated. Preferably, this is done in such a way as to stop the transfer of the particles into the mold.

The molding method of the synthetic resin foam particles of the present invention includes polypropylene, polystyrene, polyethylene, ethylene/vinyl acetate copolymer, metal salt of ethylene/(meth)acrylic acid copolymer, α-methylstyrene/styrene/acrylonitrile copolymer, Coalescence, styrene-grafted polyethylene copolymer,
It can be applied to foamed particles of thermoplastic resins such as styrene-grafted polypropylene and crosslinked resins thereof. The present invention may also be applied to foamed particles obtained from mixtures of these resins or compositions in which ethylene-propylene copolymer or 4-isobutylene rubber is blended with these resins or resin mixtures. Examples of the expanded particles include those having a bulk density of 10 to 90 i/l and a particle diameter of 2 to 10 wwm. The expanded particles may be crosslinked or non-crosslinked.

As a method for producing such expanded thermoplastic resin particles,
For example, resin particles are kneaded with a foaming agent in an extruder and extruded, and after exiting the nozzle of the extruder, pressure is released to foam and then cut to obtain foamed particles, or resin particles are mixed with water etc. in a pressure container. The resin particles are impregnated with the foaming agent by heating with stirring at a temperature around the temperature at which the resin particles soften, along with the dispersion medium, foaming agent, dispersant, etc., and then one end of the container is opened and the resin particles are heated. It contains a foaming agent obtained by suspension polymerization, a method in which resin particles are foamed by discharging a dispersion medium into an atmosphere at a lower pressure than in the container. / +7 styrene.

Styrene grafted polypropylene, Styrene grafted I
There is a method of pre-foaming expandable resin particles such as polyethylene with steam. The shape of the expanded particles includes a spherical shape, a cylindrical shape, and the like.

Furthermore, in the method of the present invention, the pressurizing gas used for pressurizing the mold and compressing and filling the expanded particles is preferably an inorganic gas such as air or nitrogen gas, but other gases such as propane, butane, isobutane, etc. , aliphatic hydrocarbon gases such as pentane; herodanized hydrocarbon gases such as dilechlorodifluoromethane, dichlorotetrafluoroethahene, methyl chloride, etc. can also be used; It is also possible to use a mixture of a small amount of the other gas mentioned above. However, compressed air is generally preferred.

In the present invention, the degree of compression of the foamed resin particles by the pressurized gas, that is, the compression ratio, can be expressed by a relational expression between the internal volume of the mold and the volume of the foamed beads filled in the mold in the atmosphere. The volume of the mold is the volume of the space formed by the convex and concave molds, and although it is difficult to measure directly, it can be considered to be substantially the same as the volume of the product molded in this space. Therefore, the compressibility (a) of the expanded particles can be determined by the following formula (W, V, and σ in the formula are as described above).

W/σ In the method of the present invention, the compression rate is generally within the range of 1 to 70%, preferably when the internal pressure of the cells of the foamed propylene particles is atmospheric pressure (01v2=
40 for the cross-linked ethylene foam particles of -"G)
~65%, 3 to 25% for foamed styrene resin particles such as polystyrene, α-methylstyrene/styrene acrylonitrile copolymer, styrene/methyl methacrylate copolymer, etc., foamed particles of styrene graph)/reethylene copolymer [Mitsubishi Yuka Perdice Co., Ltd.'s Ellen I-
(trade name) and Sekisui Plastics Co., Ltd.'s Piocelan (trade name)], it is set to 3 to 401.

In addition, when polypropylene foamed particles and crosslinked polyethylene foamed particles are subjected to pressure aging treatment with pressurized gas (air, nitrogen gas, etc.) and the internal pressure of the cells of the foamed particles is 0.5kVr112G or more, the compression ratio is 10 to 10. Let's say it's 20 inches.

Generally, if the compression rate is too low, gaps will be created at the interface where the expanded particles are fused together, resulting in poor appearance.

On the other hand, if the compression rate is too high, excessive compression, poor flow of steam between the foamed particles, poor fusion of the foamed particles, etc. will occur.

In the method of the present invention, the pressure inside the mold is increased to 0.1 to 6.0 by pressurized gas before and during filling of expanded particles.
It is best to keep it warm at 62G. This is because the bulk density of the foamed resin particles is 10 to 90 i/l, and in order to make the compression ratio of the foamed particles 1 to 70%, pressurization within this range is optimal. In other words, the pressurized gas pressure is 0.
．． This is because if it is less than 1 kVFR2G, it will be difficult to obtain a compression ratio of 1%, and if it exceeds 6.2G, there is a possibility that the compression ratio will exceed 70.

In addition, in the method of the present invention, while compressing the foamed particles using a pressurized gas that is 0.5 kg/crpt2 or more higher than the pressure inside the cavity of the mold, the foamed particles are It is desirable to divide the particles into multiple portions and supply and fill them sequentially.

The reason why the gas is compressed and filled using a gas having a pressure 0.5 ψ or more higher than the pressure inside the mold is to facilitate the press-fitting of the expanded particles into the cavity of the mold and the movement of the foamed particles in the cavity. If a pressure higher than the mold internal pressure by less than 0.5 kg/cIn2 is used, the foamed particles will not be sufficiently press-fitted into the mold cavity. Further, the reason why the supply and filling of the foamed particles into the mold is divided into a plurality of times and performed sequentially is to uniformly fill every corner of the complex-shaped mold with the foamed particles.

In order to discharge the gas existing in the gap outside the mold, steam is used to perform a degassing process. ~6.0◆ This is a method in which steam is introduced and air is removed while retaining 2). If you introduce steam and perform the degassing process while maintaining the cavity internal pressure, the shape of the foamed particles will be lower than if you restore the shape of the particles after pressure relief to their original shape and then introduce steam and perform the degassing process. Since the gap is wide, it is easy for steam to flow through, the air removal efficiency is good, and the gas existing in the gaps between the particles can be easily removed by a short air removal process.

A particularly preferable degassing treatment mode is the following mode.

■ While maintaining the internal pressure of the cavity, the steam for venting is introduced into the movable steam chamber, and is allowed to flow through the steam hole, inside the cavity, and through the steam hole, and then vented from the fixed steam chamber to the outside of the system. do.

■ With 11 maintaining the cavity internal pressure, venting steam is introduced into the fixed steam chamber, and the steam hole,
Air flows through the cavity and through the steam hole, and is vented out of the system from a movable steam chamber.

■ First, the air is removed in step [F] above, and then ■
Either the air removal process is carried out in the step (2), or the air removal process is carried out in the step (2) above, and then the air removal process is carried out in the step (2).

In the present invention, after performing the air evacuation treatment, the pressure inside the mold cavity is returned to atmospheric pressure by further depressurization, the pressurized foam particles are restored to their original shape and expanded, and then the fixed mold and After cooling both sides of the moving mold, remove the molded product.

Next, typical embodiments for carrying out the present invention using the molding apparatus shown in the accompanying drawings will be explained.

The attached drawing is a partial vertical cross-sectional view of an example of a molding device used in carrying out the present invention, in which A is a rotary supply device for compressing and filling expanded particles, and B is a mold device. C is a transport conduit for foamed particles, and D is a filling gun device for foamed particles.

First, the mold apparatus B is a space formed by the fixed mold 11 or the movable mold 12, the frames 13, 13', and the back plates 14, 14', that is, the steam chamber/par 16.
．． 16', this steam chamber 16,
16' within the pressure Pt (e.g. 0.1-6,0 W
cm2G) of pressurized gas, such as compressed air, is injected to pressurize the internal pressures of both steam chambers to the above-mentioned predetermined pressure.

Next, the one-rotation supply device A feeds the casing 2 as shown in the figure.
and a rotor 3, in which one end of a plurality of chambers 4 in the rotor 3 coincides with a foamed particle supply port 5 provided in the casing 2, and the other end of the chamber 4 is connected to a decompression line 8. Since it is configured to coincide with the suction lower, the foamed particles in the hollow 4-1 are transferred into the chamber 4 by the reduced pressure and fill it. The chamber 4 filled with foamed particles rotates with both ends sealed, and when one end of the chamber 4 reaches the foamed particle outlet 6, the other end of the chamber 4 has a pressure lower than the pressure P1, for example 0. .5 kg/cm
Since the foamed particles in the chamber 4 reach the pressurized gas outlet 9 which is pressurized to a pressure P8 higher than 2 times, the pressurized gas pressure P! The fixed mold 11 is pressurized to the above pressure pH through the foamed particle transfer conduit C and the filling gun D while being compressed.
A mold cavity 21 formed by the movable mold 12 and the movable mold 12.
It is filled inside. Since the rotor 3 of the rotary supply device A is provided with the six chambers 4 described above, the foamed particles in the Holanow 1 are divided into multiple times and sequentially formed by repeating the above operation. will be filled into the cavity.

The filling gun device has a cavity filling port 22 in the main body a.
The foamed synthetic resin particles are communicated with the filling port 22 of the cavity through the filling pipe, which has a double pipe structure and is composed of an inner pipe e' and an outer pipe e''. The structure of the filling tube is that the gap f between the inner and outer tubes e' and e'' is
is provided, and the front end of the gap f is the filling port 22.
The pressure switch P is connected to the inlet of the gap f, and a pressure switch P is mounted at the rear end of the gap f. As is obvious from the above structure, the pressure within the gap f is always constant at the filling port 22.
Since the pressure is substantially the same as the pressure at the inlet of the mold, the pressure switch Ps is set to a certain value higher than the internal pressure of the mold, for example 0.5.
If the pressure switch P is set to be activated when the pressure increases by kl,', the pressure switch P will be activated when the pressure at the inlet of the filling port 22 reaches the set pressure.

Therefore, as the foamed particles in the hopper are gradually transferred into the cavity 21 through the transfer conduit C1 and the filling gun device by the rotation of the rotor 3 as described above, the inlet of the filling port 22 of the cavity is The pressure gradually increases, and when the inlet i rises, the pressure switch P
, by operating the air cylinder h, the pusher d is moved forward, and the filling port 2 of the middle yapiti is opened.
At the same time as closing 2, the rotary supply device A for supplying foamed particles
The motor is also stopped to completely stop the supply of foam particles into the mold. In this case, depending on the type of foam particles and the shape and size of the foam molded product to be molded, when the pressure in the filling chamber 220 is higher than the mold internal pressure Pl by a certain pressure. If the operating pressure of the pressure switch P is set so that the pressure switch P is activated, the cavity of the mold can be filled with just the right amount of foamed particles when the supply of foamed particles is stopped.

Next, after filling the foamed particles into the mold is completed, at step 11, which maintains the internal pressure of the mold cavity, venting steam is introduced, for example, through the steam pipe 17' into the steam chamber 16' of the moving W12, and the steam is removed. Through the steam holes 20', 20'... of the movable type 12, the cavity 21, the fixed steam holes 20, 20..., the fixed steam chamber 16, and from the vent pipe 18 equipped with a pressure regulating valve. Vent (discharge) air out of the system. Then, cavity 21
Gas (for example, air) existing in the gaps between the foamed particles filled inside the container is evacuated by being entrained by the steam.

In this case, the air vent pipe 18' and drain discharge pipe 19' of the movable mold 12, and the steam pipe 17 and drain discharge pipe 19 of the fixed mold 11 are each closed by a valve (not shown). The valves (not shown) of the movable steam pipe 17' and the stationary vent pipe 18 are each open. Note that since the air vent pipe 18 is provided with the above-mentioned pressure regulating valve, the air venting process is performed while the internal pressure of the mold cavity is maintained at a predetermined internal pressure.

In the degassing process, while maintaining the mold cavity internal pressure, degassing steam is introduced from the steam pipe 17 of the fixed mold 11 into the steam chamber 16, contrary to the above case, and the steam holes 20, 20, . . .・Inside cavity 21, steam holes 20', 20'..., steam chamber 16
The air may be removed from the system through the air removal pipe 18' through the air removal pipe 18'.

Further, the air removal process may be performed in the first mode, and then the valve may be switched to continue the air removal process in the second mode, or, conversely, the air removal process may be performed in the second mode. After performing the degassing process in the second aspect, the degassing process may be performed in the first aspect.

These degassing processes are carried out in the steam chamber 16°16'.
Because it is necessary to stably supply steam into the steam chamber against the internal pressure Pl of
This is carried out by introducing degassing steam having a pressure higher than vctn2.

Next, after the air evacuation process, the drain discharge pipe 19,...
19' is opened, the pressure inside the chamber 21 is returned to atmospheric pressure, the compressed foam particles are restored to their original shape and expanded, and then steam at a predetermined temperature is supplied into the steam chamber 16.16'. The material is then heated, foamed and fused to form a forged foam. Next, the stationary mold 11 and the movable mold 12 are cooled by spraying water from the cooling water pipes provided in the steam chambers 16 and 16', and are further air-cooled and left to cool as necessary, and then the molds are released and molded. Take out the item.

(Examples, etc.) The present invention will be described in further detail below with reference to Examples and Comparative Examples.

Example of producing expanded particles In an autoclave with an internal volume of 3 tons and a pressure resistance of 50 kg//-rn2, 1400 parts of water (parts by weight, the same applies hereinafter), ethylene-propylene random copolymer (Mitsubishi Oil & Chemical Co., Ltd. trade name: Mitsubishi Noblen FG3, ethylene content 3% by weight)6
00 parts, 15 parts of tribasic calcium phosphate as a suspending agent, and 0.05 parts of sodium dodecylbenzenesulfonate as a surfactant.
95 parts of butane as a blowing agent, 430 rp.
The temperature was raised from room temperature to 135° C. over 1 hour under stirring for 1 hour, and when the temperature was maintained for 10 minutes, the internal pressure of the autoclave reached 25°C and 62G. Open the discharge nozzle valve at the bottom of the autoclave and pour the contents into the atmosphere.
While stirring at m, the mixture was discharged for 2 seconds to cause foaming.

The resulting super-foamed particles had a bulk density of 2817/l.

Example 1 Using a molding apparatus as shown in the attached drawings, foamed particles of the ethylene-propylene random polymer 4 reamer having a bulk density of 28 g/l obtained in the above-mentioned foamed particle manufacturing example were molded. The details of the molding machine, mold, rotary supply device for compression filling, filling gun, and molding method used in that case were as follows.

Molding machine: DAIYA-600LF (Daisen Kogyo Co., Ltd. product name) Mold: Mold that can obtain a molded product with a width of 300 mm x length of 300 mm + x height of 50 mm (inner volume: 4.5 tons) Rotary supply device for compression filling: Number of chambers: 6 Chamber size: 35 φ x 52 m Length: 5
0cc Filling gun: DAIYA-Feeder (Daisen Industries Co., Ltd. product name), diameter 30 days The molding method first closes the mold and increases the mold internal pressure P1 to 3.0 cc with compressed air. The pressure was increased to skyJa. Next, the bulk density is 28. ! Expanded particles of 9μ were sequentially filled into the mold using rotary feeder A, using compressed air with a pressure of 5.5 kll/an2G as P2, in portions at intervals of 0.1 seconds. During the filling, the indoor pressure Pt is 3.5 i:
The pressure regulating valves attached to the exhaust pipes 18 and 18' were operated so that the pressure was maintained at □2G.

The supply of foamed particles into the mold is stopped during the filling gun device.
The test was carried out using a commercially available pressure switch (Daiichi Keiki Seisakusho Co., Ltd., trade name: DU type Pressure Goo) attached to 1. That is, the operating pressure 'f of this pressure switch:
4. Set Okimm2G, and when the pressure at the inlet of the cavity filling port reaches this value, immediately operate the air cylinder g of the filling gun and press the plunger d.
advance to the position of the filling port 22 of the T-shaped cavity,
At the same time as the filling port 22 was closed, the motor of the rotary supply device A was stopped, thereby stopping the supply of foamed particles indoors.

After stopping the supply of foamed particles, open the steam pipe 17'; 3.
7ψ-2G steam for 5 seconds in movable chamber 1
6', the pressure inside the mold is maintained at 3.5 kf'am2G by the pressure regulating valve attached to the vent pipe 18, and then the air is vented. Steam of 3.7ψ62G was introduced into the mold 16 for 10 seconds, and air was vented through the vent pipe 18' while maintaining the pressure P1 inside the mold at 3.5ψ62G.

Next, the steam pipes 17 and 17' are closed to stop the supply of steam, and the drain discharge pipes 19 and 19' are opened to instantly return the internal pressure of the chambers 16 and 16' and the cavity 21 to atmospheric pressure, thereby causing foaming. After restoring the particles to their original shape and expanding them, a movable and fixed steam chamber 1
At the same time, 4kllAytt2G of steam was introduced into 6 and 16' for 10 seconds to heat the foamed particles and fuse them.9.

Finally, the foam molded product was water-cooled for 50 seconds, then air-cooled for 8 seconds, and then taken out and dried after cooling for another 60 seconds.The weight of the foamed product was 27+1 (bulk density 60 fi/l'), and the foaming during molding was The compressibility of the particles was 53%.

The obtained molded product is filled with foamed particles to every corner, and there are few gaps between the particles (2 surface gaps/25 c
ttt2), has excellent fusion bonding (100% fusion rate), and the incidence of defective products is extremely small at 2. The molding conditions and the incidence of defective molded products were as shown in Table 1.

Comparative Example 1 Using an OMRON f (7CN digital counter (trade name of Tateishi Electric Co., Ltd.), filling was stopped when the amount of foamed particles supplied into the cavity of the mold reached 190 in the count number of chamber 4, In other respects, molding was carried out in accordance with the method of Example 1. The molding conditions and the incidence of defective molded products were as shown in Table 1.

Table 1 *1: Refers to the compression ratio calculated using the above formula (Table 2 is the same) Various molded foam molded products were molded using the various foamed particles detailed below, using the conditions shown in Table 2 as the molding conditions, and otherwise following Example 1 or Comparative Example 1. did. The results are shown in Table 2.

Crosslinked polyethylene foam particles: Particle size lO■, degree of crosslinking is 55 in terms of r ratio, bulk density 15
．． 69μ styrene-modified polyethylene foam particles: particle size 5m, bulk density 31.8. ! ilμ, pre-expanded particles with styrene/preethylene weight ratio = 171 Polystyrene foam particles: Pre-expanded particles with a particle size of 311II11 and a bulk density of 209/I- (c) Effects of the invention The present invention provides molds with uniform density distribution and excellent appearance. Foamed products can be easily molded with a low incidence of defective products.

[Brief explanation of drawings]

The accompanying drawings are partial longitudinal cross-sectional views of an example of a molding apparatus used in carrying out the present invention, and each reference numeral in the drawings indicates the following. A...Rotary supply device for compressing and filling expanded particles, B
... Metal wheel device, C... Foamed particle transfer conduit, D...
・Filling gun device, 1...Popper for foam particles, 2...
・Casing, 3... Rotor, 4... Chamber,
5... Foamed particle supply port, 6... Foamed particle discharge port, 7
...Decompression line suction port, 8...Decompression line, 9...
- Pressurized gas outlet, 10... Pressurized gas line, 11.
...Fixed type, 12...Movable type, 13, 13'...
Frame, 14, 14'...Backing metal, 16, 16'
... Steam chamber, 17, 17'... Steam pipe, 1 B, 18'... Ventilation pipe, 19, 1
9'...Drain discharge pipe, 20.20'...Steam hole, 21...Mold cavity, 22...Cavity filling port, a...Filling gun body, b...Main Hole, C
... Branch hole, d... Plunger, e... Filling pipe, f... Gap, g... Air cylinder.

Claims (1)

[Claims] 1) Synthetic resin foam particles are supplied and filled into a mold cavity pressurized with pressurized gas while being compressed using pressurized gas higher than the internal pressure of the mold, and then foamed by steam heating. In a method of forming a molded foamed product by fusing particles, a pressure detection device is provided at the inlet of a cavity filling port of the mold,
A method for molding foamed synthetic resin particles, characterized in that supply of the foamed particles into the cavity is stopped when the pressure detected by the pressure detection device becomes higher than the pressure inside the cavity by a predetermined pressure. 2) The molding method according to claim 1, wherein the supply of expanded particles is stopped when the pressure detected by the pressure detection device becomes 0.5 to 1 kg/cm^2 higher than the cavity internal pressure. 3) The method according to claim 1 or 2, wherein the foamed particles are sequentially supplied into the cavity in multiple steps. 4) a main hole communicating with the filling port of the mold cavity, a branch hole communicating with the synthetic resin foam particle transfer conduit, a filling pipe with a double pipe structure connecting the cavity filling port and the main hole, and In the filling gun device, the filling gun device has a plunger capable of closing the cavity filling port, and communicates the gap between the inner tube and the outer tube of the filling tube with the double tube structure with the inlet portion of the cavity filling port. A filling gun device for synthetic resin foam particles, characterized in that a pressure detection device is installed in the gap between the inner and outer filling tubes of the filling tube having the double-tube structure.