JPS63290721A - Filling method for raw material particles - Google Patents

Abstract

PURPOSE:To increase the compressive transfer efficiency and filling efficiency of raw material particles by feeding pressurized air into the inside of a molding cavity around a filling opening of the cavity, transferring at once raw material particles brought to the filling opening into the cavity by means of pressurizing air and keeping filling, and then blowing back the surplus raw material particles remaining around the filling opening by means of pressurized air. CONSTITUTION:An introduction opening 93 of pressurized air is formed around an end opening, or a cavity opening 24, of a filling machine 9. A feeding valve 94 to control feeding of pressurized air is installed at said introduction opening 93. The introduction opening 93 is opened to be able to fill the pressurized air to the inside of a molding cavity 23 by the opening action of a pressurized air feeding valve 94. The pressurized air out of said introduction opening 93, therefore, is provided with a function to compressively transfer the raw material particles transfer compressively in one motion to the end opening section of the filling machine 9 into the molding cavity 23 through a cavity opening section 24. After the completion of filling, surplus raw material particles residing or remaining around the molding cavity opening section 24 are blown back to the side of a pressure silo 8 in cooperation with the pressure reducing suction force on the side of the pressure silo 8.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for filling raw material particles, and more specifically,
The present invention relates to a filling method useful for filling raw material particles made of expandable thermoplastic resin particles into the cavity of a foam molding mold.

<Prior art and its problems> Conventionally, in foam molding, so-called bead molding using raw material particles made of expandable thermoplastic resin particles has been known.

In this bead molding, for example, (1) a filling device is connected to the filling port of the mold cavity, and pressurized air is introduced into the filling device, and the Venturi effect generated at that time causes the raw material particles in the raw material hopper etc. The raw material particles are sucked into the filling device and accompanied by this pressurized air, and then sent into the mold cavity for filling. When the filling of the raw material particles into the mold cavity is completed, the pressurized air is caused to flow back to the raw material hopper side. Therefore, a filling method is adopted in which excess residual raw material particles in the filling device are returned to the raw material hopper. A closed hopper that can be pressurized is prepared, and the raw material particles in the hopper are forced and filled into the mold cavity through the filling device by the pressurized air supplied into the closed hopper, and the raw material particles are filled into the mold cavity. When filling is completed, a filling method is used in which the remaining raw material particles in the filling device are returned to the closed hopper side in cooperation with the suction by the closed hopper under reduced pressure.

By the way, in the above-mentioned filling method (1), since the raw material particles in the raw material hopper are transferred to the filling machine only by the suction force of the filling machine, there are no gaps between the raw material hopper and the filling opening of the mold cavity. It is not possible to create a sufficient pressure difference,
For example, the moving speed or filling speed of raw material particles becomes slow, and it takes a long time to fill the mold cavity with raw material particles.

Furthermore, if the exhaust in the mold cavity is not sufficient, this tendency becomes noticeable, and the mold cavity may not be completely filled with raw material particles.

For this reason, there is sufficient rubbing between the molds (a slit formed between the molds to remove the pressure and air that has been introduced into the mold cavity and finished pumping the raw material particles, or a gap provided between the mold mating surfaces). ) has been proposed, which improves the exhaust inside the mold cavity and makes it possible to increase the pressure difference. However, with this method,
Raw material particles enter the slits formed between the molds and the gaps between the mold mating surfaces, causing cracks etc. on the mold mating surfaces of the molded product. There is also the problem that there is a difference in specific gravity between the container and the bottom, and the filling condition is not good.

In addition, in the above filling method (I), the raw material particles can be directly pushed into the mold cavity by the pressurized air from the closed hopper, so even if the cracking provided between the molds is insufficient, Although it has the advantages of increasing the filling speed of raw material particles, improving the exhaust effect and preventing the occurrence of raw material filling defects, and being able to uniformly fill the mold cavities, it is possible to When the distance to the mold cavity is long, or when the diameter of the pipe is increased for mass transportation, the pressure air applied to the closed hopper must be adjusted to a considerably high pressure to take into consideration the pressure loss that occurs during air transportation. It is necessary to keep it. Such pressure loss deteriorates the pumping efficiency and filling efficiency of raw material particles.

This requires a sealed hopper with sufficient pressure resistance and related equipment to increase the pressure of the pressurized air, which increases the cost of the equipment and complicates the equipment. Become.

Due to the deterioration of pumping efficiency due to the above-mentioned pressurized air,
Another problem arises in that the pumping efficiency of raw material particles during blowback is also reduced.

<Purpose of the Invention> This invention was made in view of the above-mentioned problems, and it improves the filling condition by making cracking omissible, and also achieves this without complicating the equipment or increasing the cost of the equipment.
It is an object of the present invention to provide a method for filling raw material particles that improves the pumping efficiency and filling efficiency of raw material particles.

Means for Solving the Problems> In order to achieve the above object, the method for filling raw material particles of the present invention includes filling raw material particles made of expandable thermoplastic resin particles into a mold cavity of a foam molding mold with air. In the filling method of transporting and filling, pressurized air directed into the mold cavity is supplied near the filling port of the mold cavity, and the raw material particles conveyed to the filling port are transported into the mold cavity at once by the pressurized air. After the filling is completed, surplus raw material particles remaining near the filling port are blown back by the pressurized air.

According to the method for filling raw material particles with the above configuration, the raw material particles that have been pneumatically transported to the vicinity of the filling port of the mold cavity are forced into the mold cavity by newly supplied pressurized air near the filling port. Since the raw material particles can be conveyed under pressure, the raw material particles can be conveyed without reducing the filling speed. This makes it possible to omit cracking, which causes the generation of flakes, and to uniformly fill the mold cavity with raw material particles.

Moreover, since new pressurized air is supplied in order to forcefully feed the raw material particles that have been transported near the filling port into the mold cavity, the pressure loss during transportation can be compensated for by the pressure of this new pressurized air. For example, even when the distance from the closed hopper to the filling device and into the mold cavity is long, or when the diameter of the vibrator is increased for mass transportation, the pumping efficiency and efficiency of raw material particles into the mold cavity can be improved. Filling efficiency can be improved without any problem.

In addition, since pressurized air is supplied to the vicinity of the filling port to efficiently pump the raw material particles, after filling the raw material particles into the mold cavity, for example, when the pressure on the closed hopper is released, Blowback can be performed efficiently.

<Example> Next, an example of the present invention will be described below with reference to the drawings. For convenience of the following explanation, first, a schematic structure of a molding apparatus that can be suitably used in the raw material particle filling method according to the present invention will be described.

In FIG. 1, the molding device is equipped with a pressure silo (8) corresponding to the conventional closed hopper described above and a mold (20) for bead molding, and the pressure silo (8) is controlled by a predetermined control. For example, 0.5 to 8.0k depending on the board (not shown)
It is formed to be able to enclose pressurized air set to vd.

The pressure silo (8) includes a raw material supply valve (1) that controls the supply of raw material particles (or pre-foamed raw material particles) as expandable thermoplastic resin particles, and a pressure supplied to the pressure silo (8). Air supply valve (2) that controls air, vacuum suction valve (3) that controls the reduced pressure level in the pressure silo (8)
, level meter (4), exhaust valve (5) and raw material discharge valve (6)
The pressure silo (8) is equipped with one or more on-off valves, and each on-off valve is provided corresponding to each opening formed in the pressure silo (8). Note that the reference numeral (7) in the figure is a viewing window, and the level meter (4) detects, for example, when the raw material particles supplied into the pressure silo (8) have accumulated to a certain height. and sends a detection signal to a designated control panel.
The supply of raw material particles to the mold (20) can be controlled.

The mold (20) is composed of a pair of molds, a cavity mold (21) and a core mold (22), which can be opened and closed.
A mold cavity (23) is formed between the two full molds (21) and (22). Then, raw material particles are introduced into the mold cavity opening (24) provided in the cavity mold (21).
3) A filling device (9) is attached for pressure-feeding and filling into the container.

Note that at least one of the cavity mold (21) and the core mold (22) is provided with a large number of known core vents or other steam holes for blowing out steam.

The filling device (9) is provided with a supply port (90) for raw material particles that is connected to one of the raw material discharge valves (6) through the connection of the filling hose (15). the tip opening,
It is inserted into the mold cavity (23) and attached. The filling device (9) has 1. A cylinder (not shown) that opens and closes the tip opening of the filling device (9) by reciprocating motion
is loaded, and a filling lid opening valve (91) and a filling device valve (92) for switching the cylinder are attached. That is, by operating the filling lid opening valve (91),
Raw material particles are supplied from the filling device (9) into the mold cavity (23), and by operating the inter-filler valve (92), the raw material particles are supplied from the filling device (9) into the mold cavity (23). The supply of particles will be cut off.

Next, as a characteristic structure for achieving this invention, the tip opening of the filling device (9), that is, the mold cavity opening (2
A pressure air inlet (93) is formed near 4), and a supply valve (94) for controlling the supply of pressurized air is attached to this inlet (93). . In this case, the inlet (93) supplies pressurized air pressurized to 2.0 to 7.0 ki4 by a predetermined control panel into the mold cavity (23) by the opening operation of the pressurized air supply valve (94). It has an opening so that it can be sent out towards. Therefore, the pressurized air from this inlet (93) transports the raw material particles that have been pumped to the tip opening of the filling device (9) through the mold cavity opening (24) and into the mold cavity (23).
It has the function of pumping inward all at once. and,
After filling is completed, excess raw material particles that have accumulated or remain in the vicinity of the mold cavity opening (24) are removed from the pressure silo in cooperation with the vacuum suction force on the pressure silo [F]) side. 3)
It has a function of blowing back toward the side (blowback function).

Next, a method for filling raw material particles according to the present invention will be described using a molding apparatus having such a configuration.

First, as shown in Fig. 1, in the step of introducing raw material particles into the pressure silo B) (see raw material particle injection ■ in Fig. 2), the vacuum suction valve (3) is opened and a predetermined pump, etc. The pressure inside the pressure silo (8) is reduced. At the same time, the raw material supply valve (
1) is opened to suck raw material particles stored in a storage tank (not shown) into the pressure silo (8). Then, when a predetermined amount of raw material particles are supplied into the pressure silo (8) as detected by the level meter (4), the vacuum suction valve (3) and the raw material supply valve (1) are closed.

As raw material particles, expandable thermoplastic resin particles such as polystyrene, polyethylene, or polypropylene are typically used.

Next, the air supply valve (2) is opened and pressure air at a predetermined pressure is introduced into the pressure silo (8) (see pressure silo pressurization (2) in Fig. 2), and the pressure air is brought into the pressure silo (8) at a pressure of 0.5 to 8. 0
Pressurize within the range of 94.

On the other hand, the cavity mold (21) and the core mold (22) are clamped without cracking the mold cavity (23) for the subsequent filling process.

Filler. In the process (see raw material particle filling ■ in Figure 2), the air supply valve ■ is opened and the pressure silo (8)
While keeping the inside pressurized, open the raw material discharge valve (6),
At the same time, the filling mold opening valve (91) is opened to drive the cylinder, the filling machine (9) is driven to open as much as possible, and the pressurized air supply valve (94) is opened. This allows the pressure silo (8)
The raw material particles inside can be forcibly air-transported to the tip opening of the filling device (9), that is, the mold cavity opening (24), while the new pressure from the pressurized air inlet (93) It can be backed up with air and can be filled into the mold cavity (23) under pressure.

When the filling of the raw material particles into the mold cavity (23) is completed in this way, the first blowback (see pullback ■ in FIG. 2) and the second blowback (see pullback ■ in FIG. 2) are completed. To do this, leave the above air supply valve ■ open,
Instead, the exhaust valve (5) is opened to bring the inside of the pressure silo (8) to the atmospheric pressure level, for example.

In the first blowback, the filling type opening valve (91) and the pressure air supply valve (94) are kept open, and the pressure air from the pressure air supply valve (94), which is also kept open, causes Excess residual raw material particles accumulated near the tip opening of the filling device (9), ie, the mold cavity opening (24), are returned to the pressure silo (8).

Then, the filling mold opening valve (91) which was in the open state during filling.
The first blowback is completed by closing.

In the second blowback, the filling device closing valve (92) is driven to close the filling device (9), and the raw material particles once filled into the mold cavity (23) are released from the pressurized air supply valve (94). Pressurized air or the like is used to prevent it from spilling into the vicinity of the tip opening of the filling device θ), that is, the mold cavity opening (24).

Next, with the pressure air supply valve (94) in the open state, the pressure air from the pressure air supply valve (94) causes the filling device (9) to leak in the first blowback.
Excess residual raw material particles accumulated near the tip opening, ie, the mold cavity opening (24), are returned to the pressure silo (8).

Thereafter, the second blowback is completed by closing the exhaust valve (1), the raw material particle discharge valve (6), and the pressurized air supply valve (94). At the same time, the filling of raw material particles is completely completed.

Note that the first blowback may be omitted by stopping the driving of the filling type opening valve (91) immediately after filling and directly performing the second blowback. In addition, during charging of raw material particles into the pressure silo (8) and pressurizing the pressure silo (8), the filling type opening valve (91) may be opened in advance; As long as the pressure inside the silo (8) has risen sufficiently, the air supply valve (2) may be kept closed.

Also, instead of opening the exhaust valve (5) during the first blowback and the second blowback, the vacuum suction valve (
3) It is also preferable to open the pressure silo (8) and provide the inside of the pressure silo (8) in a reduced pressure state. According to this, the pressure silo (8) side can have a reduced pressure suction function.

In addition, in the above-mentioned filling method, it was explained that it was carried out in a non-cracking state, but in some cases, both molds (50) and (51) of the molding mold (20) are not completely clamped, and a certain amount is filled. You can save the cracking.

A time chart during filling of the raw material particles is shown in FIG. In addition, in the figure, the double-headed straight line indicates the open state of each valve.

Next, a specific example according to the present invention and a comparative example according to the conventional method will be compared and explained.

For example, in order to obtain a molded product with a wall thickness of 2.6M, [Specific Example 1]
] In specific example 1, raw material particles made of expanded polystyrene with a particle size of 0.5 to 1 Omm s and an expansion ratio of 18 times are pumped from a pressure silo set at a pressure of 2 and OkcJ4 to a predetermined mold, and By newly supplying pressurized air at a pressure of 5 to 0 kg near the filling opening of the mold cavity, the raw material particles that have been transported up to this point are further forced into the mold cavity. It was pumped to. In this case, Crab King was omitted.

[Specific Example 2] In Specific Example 2, raw material particles made of expanded polystyrene with a particle size of 1.0 to 2.0 M and an expansion ratio of 56 times were heated to a pressure of t, oh.
The pressure is fed from a pressure silo set at 4 to a predetermined mold, and a pressure of 4.0 k is applied near the mold cavity opening of this mold.
By newly supplying pressurized air set to i4, the raw material particles that had been conveyed up to this point were forced into the mold cavity in the same manner as in Example 1. And in this case too, cracking was omitted.

[Comparative Example 1] In Comparative Example 1, compared to the above-mentioned Specific Example 1, the pressure in the pressure silo was set to, for example, the atmospheric pressure level, and the pressure air introduced near the mold cavity opening was set to a pressure of 4.0 to 94. . Moreover, a crack of 2.0 mm was provided between the molds.

[Comparative Example 2] In Comparative Example 2, compared to Specific Example 1, the pressure in the pressure silo was similarly set to the atmospheric pressure level, and the pressure air introduced near the mold cavity opening was set at a pressure of 4.0 kcJ4. However, in this case, as in Example 1, the crab king was omitted.

[Comparative Example 3] In Comparative Example 3, compared to Specific Example 2, the pressure in the pressure silo was also set to the atmospheric pressure level, and the pressure air introduced near the opening of the mold cavity was set to a pressure of 2.0! It was set to J. Moreover, a crack of 2.0 mm was provided between the molds.

[Comparative Example 4] In Comparative Example 4, compared to Specific Example 2, the pressure in the pressure silo was also set to the atmospheric pressure level, and the pressure air introduced near the mold cavity opening was set at a pressure of 2.0 to 94. . However, as in Example 1, the club king was omitted from the mold in this case. The above results are shown in Table 1.

(Hereinafter, blank space) Next, for example, in order to obtain a molded product with a wall thickness of 25 mm,
Specific Example 3] In Specific Example 3, raw material particles made of expanded polystyrene with a particle size of 2.0 to 3.0 mm and an expansion ratio of 40 times,
By force-feeding air from a pressure silo set at a pressure of 13a to a predetermined mold, and newly supplying pressurized air at a pressure of 4.0h4 near the mold cavity opening of this mold, The raw material particles that had been transported up to this point were further forcibly fed into the mold cavity.

In this case, cracking was omitted, and the diameter of the filling device was set to 20.0I+1171.

[Specific Example 4] In Specific Example 4, raw material particles made of expanded polystyrene having a particle size of 2.0 to 3.0 kg and an expansion ratio of 40 times were heated to a pressure of 3.0-
It is fed under pressure from a pressure silo set on a paddle toward a predetermined mold, and a pressure of 4.0 k is applied near the mold cavity opening of this mold.
By newly supplying pressure air set to lj, i, the raw material particles that have been transported up to this point are
It was pumped into the mold cavity in the same manner as above. In this case as well, cracking was omitted, and the diameter of the filling device was set to 14.0 mm.

[Comparative Example 5] In Comparative Example 5, compared to Specific Example 3, the pressure in the pressure silo was set to the atmospheric pressure level, and the pressure air introduced near the mold cavity opening was set at a pressure of 4.01q4. However, in this case, as in Specific Example 3, cracking was omitted.

[Comparative Example 6] In Comparative Example 6, compared to Specific Example 4, the pressure in the pressure silo was set to the atmospheric pressure level, and the pressure air introduced near the mold cavity opening was set to a pressure of 4. It was set to ohJ. However, in this case as well, cracking was omitted as in Specific Example 4. The above results are shown in Table 2.

(Hereinafter, blank space) Thus, as can be seen from Table 1 above, the conventional filling method (Comparative Example 1.3) required cracking of, for example, 2.0 mm, whereas Specific Example 1.2 In,
It enables filling in a non-cracking state, eliminates one of the causes of paris occurrence, and enables uniform filling, which improves the filling state.
The filling time could be reduced to approximately 1/4 or less. Regarding Comparative Example 2.4 in which Club King was omitted,
The filling condition was poor and the total filling time D1 was omitted.

Further, as can be seen from Table 2 above, although the filling state of the raw material particles on each side is good, the filling time for each side differs depending on the size of the filler diameter. Specific example 3.
Regarding the filling time by pressurized filling in No. 4, compared to the filling time in each corresponding comparative example No. 5.6, the filling time was about 1/2 to 1110
could be shortened to.

<Effects of the Invention> According to the method for filling raw material particles configured as described above,
Since it can be filled without reducing the filling speed of raw material particles,
The raw material particles can be uniformly filled into the mold cavity, and the pressure loss during transportation can be compensated for by the pressure of this new pressurized air. In cases where the distance between the molds is long or the diameter of the pipe is increased for mass transportation, it is possible to improve the pumping efficiency and filling efficiency of the raw material particles into the mold cavity without any problems. Cracks that are formed can be omitted and the filling condition can be improved.

In addition, since pressurized air is supplied to the side near the filling port to efficiently pump the raw material particles, after filling the raw material particles into the mold cavity, for example, when the pressure of the pressure silo is released, Efficient blowback can be performed, there is no need to increase the pressure resistance of each related device, and in addition to the above effects, the pumping efficiency of raw material particles can be improved without complicating the equipment or increasing the cost of the equipment. It has various unique effects, such as being able to improve filling efficiency.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a molding apparatus that can be suitably used in the raw material particle filling method according to the present invention, and FIG. 2 is a time chart during filling of raw material particles. (9)... Filler (20)... Molding mold (2
1)...Cavity type (22)...Core type (23)...Mold cavity (94
)...Pressure air supply valve patent applicant Sekisui Plastics Co., Ltd. Representative Patent attorney Hiroshi Kamei (and 3 others)

Claims (1)

[Claims] 1. Raw material consisting of expandable thermoplastic resin particles Particles are air transported into the cavity of the foam mold. In the filling method of sending and filling, the mold cavity is Directed into the mold cavity near the filling port of Supply pressurized air and transport it to this filling port The raw material particles that have been It is pumped into the cavity at once and filled. After filling is completed, there is no residue left near the filling port. Excess raw material particles are removed using the above pressure air. The material is characterized by blowback. How to fill the material particles.