JP2693340B2 - Device for controlling the expansion ratio of pre-expanded resin particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates in particular be applied to a batch type pre-foaming machine, expansion ratio control apparatus of the pre-expanded resin particles to automatically control the pre-expansion ratio of the foamable synthetic resin particles <br/> It is about.

[0002]

2. Description of the Related Art Conventionally, in order to control the pre-expansion multiple of expandable synthetic resin particles such as expandable polystyrene, an amount commensurate with the pre-expansion multiple is based on the effective volume of a pre-expanding machine including a foam can body. The input raw material of No. 2 is calculated as a theoretical value and is input as a set value into the measuring instrument. For example, a predetermined weight of raw material is automatically weighed in a weighing tank provided with a load cell for weight measurement.

Subsequently, the metered raw material is charged from the upper portion of the pre-foaming machine, and then steam and compressed air are blown from the perforated plate on the bottom surface of the pre-foaming machine, and the heat medium foams and expands. This foaming is continued until the supply of steam is stopped on the basis of a signal generated when the foamed particles reach the level meter provided near the upper end of the pre-foaming machine.

By the way, the pre-expansion multiple varies depending on the blow steam pressure value, aeration (compressed air input value), the type of raw material compounding agent, the quality of steam used, and the like. Therefore, when it is desired to accurately control the pre-expansion multiple, the operator samples the pre-expanded resin particles that have been foamed and is discharged, using a measuring cup, and calculates the net weight of the pre-expanded resin particles and the volume of the measuring cup. The actual situation is to repeat the work of calculating the actual prefoaming multiple and correcting the raw material input amount appropriately according to the error from the set value.

[0005]

However, as described above, in the method in which the operator samples the pre-expanded resin particles to measure the pre-expansion multiple and corrects the raw material input amount as necessary, the measurement by the measuring cup and There is a problem that it takes time and effort to correct the amount of raw material input and the work becomes complicated.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, a device for controlling the expansion ratio of pre-expanded resin particles according to the present invention is a pre-expanded resin prepared by pre-expanding a raw material made of synthetic resin particles in a pre-expanding machine. In obtaining the particles, in the expansion ratio controller for the pre-expansion resin particles for controlling the pre-expansion multiple of the pre-expansion resin particles, the pre-expansion for pre-expanding by supplying the raw material based on the input pre-expansion multiple
And the pre-expanded resin particles discharged from the pre-expanding machine.
The storage hopper to be stored and the above-mentioned storage hopper.
And a damper that can open and close the opening on the lower end surface
Of a predetermined capacity of the storage container and the storage hopper
A sump that connects the lower part and the upper side of the weighing container.
Ring tube and pre-expanded resin discharged to the above storage hopper
Transfer particles to the weighing container via the sampling tube
And send compressed air to the sampling tube for filling
Weigh the sampling air duct and the weighing container above.
Pre-expanded resin particles in the measuring container and the measuring means for
The sampling operation for filling the
The weight of the pre-expanded resin particles measured by the measuring means and the upper
From the volume of the measuring container and the expansion ratio of the pre-expanded resin particles,
A multiple measurement device control panel for conversion is provided .

[0007]

According to the above construction , when the operator inputs the preset pre-expansion multiple, the amount of the raw material commensurate with the preset pre-expansion multiple is supplied to the pre-exposure machine to start the pre-expansion. And
The pre-expanded resin particles that were pre-expanded and discharged from the pre-exposure machine to the storage hopper were collected through the sampling tube.
Transfer to a weighing container with a specified volume installed above the storage hopper
Is done. At this time, the pre-expanded resin particles are transported by the sample
Compression sent to the sampling tube by the ring air tube
Made by air. The sampling tube is stored in the above
Communicate the lower part of the hopper and the upper side surface of the weighing container.
As a result, the pre-expanded resin particles are stored in the hopper.
Immediately after being transported from the
It is. Then, the prefoaming multiple of the prefoamed resin particles can be detected by measuring the weight of the measuring container.
As a result, the actual pre-expansion multiple of the pre-expanded resin particles is detected, this is compared with the set pre-expansion multiple, and the raw material supply amount can be controlled in the direction of reducing the difference thus obtained. The expanded resin particles can be manufactured so that the actual pre-expansion multiple varies within a predetermined range of the set pre-expansion multiple.

Therefore, in the above construction, the pre-foamed resin particles discharged from the pre-foaming machine can be conveyed by, for example, compressed air or the like to be directly filled in the measuring container from the storage hopper. Since it is possible to measure the actual prefoaming multiple
It becomes easier and the operator only has to set the preset pre-expansion multiple.

Further, conventionally, the pre-expanded resin particles have been scooped and filled into the measuring cup by hand so that the upper surface of the pre-expanded resin particles is flush with the upper end of the measuring cup. Since the packing rate of the particles is likely to change and the measurement error becomes large, the foaming multiple of the pre-foamed resin particles converted is also unstable.

However, in the above structure, the storage
Pre-expanded resin particles are directly applied from the hopper to the weighing container at a specified pressure.
Since it is filled in close contact, it is filled more uniformly and quickly than in the past , which makes it possible to improve work efficiency and
The filling amount can be stabilized, and the measurement error in detecting the prefoaming multiple can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In a device for controlling the expansion ratio of pre-expanded resin particles, for example, as shown in FIG. 1, a batch-type pre-exposure machine 1 is used. A predetermined amount of a certain raw material is charged, and after the whole amount is heated, pre-expanded and discharged, a new predetermined amount of the raw material is charged into the pre-expanding machine 1 from which the pre-expanded resin particles have been discharged, and the next cycle is started. It is supposed to be started.

As the above raw material, for example, synthetic resin particles such as polystyrene, polyethylene, polypropylene, etc. are used, while as the foaming agent, volatile hydrocarbons such as pentane, butane are used.

A predetermined amount of raw material is supplied to the pre-foaming machine 1 from a raw material supply loader 2 through a hopper scale 3 having a load cell type raw material weighing scale 3a. Further, the hopper scale 3 is provided with an electromagnetic opening / closing valve 3b for controlling the supply of the above raw material.

A blow steam pipe and a compressed air blow pipe (not shown) are connected to the bottom of the pre-foaming machine 1 so that steam and compressed air are blown into the pre-foaming machine 1 and the stirring blades 1a in the pre-foaming machine 1 are also connected. Is rotated by the motor 1b to perform pre-foaming. The end of the pre-foaming is detected when the upper surface of the expanded pre-foamed resin particles reaches a level meter 1c of a tuning fork type or the like attached at a predetermined position above the pre-foaming machine 1.

The signal from the level meter 1c is output to a pre-foaming machine control board 10 described later, and the pre-foaming machine control board 10 controls the blow steam pipe and compressed air blowing pipe control valves and the motor 1b. To be done.

A discharge hatch 4 is provided on the lower side surface of the pre-foaming machine 1, and a discharge valve 4a for opening and closing the discharge hatch 4 is provided. The discharge valve 4a is reciprocated by an air cylinder 4b controlled by the pre-foaming machine control panel 10 to open and close the discharge hatch 4.

A storage hopper 5 is disposed on the side of the pre-foaming machine 1 and below the discharge hatch 4, and an opening is provided in the upper surface of the storage hopper 5 so that the pre-foaming machine 1 has a preliminary opening. The pre-expanded resin particles that have been foamed are discharged into the discharge hatch 4.
And discharged to the storage hopper 5.

Further, since the pre-expanded resin particles which have been humidified by the steam and adhered to form a dumpling are disintegrated and the pre-expanded resin particles having a predetermined particle size or less are sieved, the upper part in the storage hopper 5 is Is provided with a sieving / sieving net 5b having a predetermined mesh inclined so as to descend from the discharge hatch 4 side to the other. Although not shown, the sieving / sieving net 5b is horizontally moved by a driving means such as a motor. It reciprocally vibrates in the direction.

Above the storage hopper 5,
In order to measure the expansion ratio of the pre-expanded resin particles, a substantially cylindrical weighing container 6 made of acrylic or the like with a predetermined capacity, for example, 30.64 L is arranged with its axis substantially vertical. The material of the measuring container 6 is not particularly limited as long as it has a predetermined strength, but a transparent material is desirable so that the filling state inside can be identified.

The measuring container 6 has openings at the upper and lower ends, and a mesh wall 6a having a mesh through which air can pass but pre-expanded resin particles cannot pass is provided at the opening on the upper end surface thereof.
A measuring container damper 6b for opening and closing the opening is attached to the opening of the lower end surface of the measuring container 6. Further, a scattering prevention hopper 9 is arranged between the weighing container 6 and the storage hopper 5 so as to return the pre-expanded resin particles from the weighing container 6 to the storage hopper 5 without waste.

Therefore, by closing the measuring container damper 6b, the measuring container 6 has a predetermined capacity, and the pre-foamed resin particles are filled from the storage hopper 5 into the measuring container 6 by using compressed air as described later. However, the air can escape from the mesh wall 6a, and the filling of the pre-foamed resin particles is not hindered.

Further, a sampling pipe 7 for connecting the weighing container 6 and the lower part of the storage hopper 5 to each other is provided with a sampling pipe 7.
Is connected to the upper side surface of the sampling pipe 7, and a sampling blower pipe 8 for sending compressed air to the measuring container 6 is connected to the sampling pipe 7.
Is connected so that the pre-expanded resin particles can be conveyed from the storage hopper 5 to the weighing container 6 as described above.

The sampling blower pipe 8 is provided with an opening / closing valve 8a for opening and closing it, and further, though not shown, through a control valve for adjusting the air pressure of the compressed air,
It is connected to a tank that stores compressed air compressed by a compressor.

On the other hand, in the center of the peripheral surface of the weighing container 6, for measuring the weight of the weighing container 6, for example, a strain gauge type load cell (maximum weighing value of 10 kg) is provided with a weighing means 6c at 3-4 intervals. Individually installed, therefore, the weighing container 6 is hung by each of the weighing means 6c ...

Further, the bellows portion 7a is provided at the bent portion of the sampling pipe 7 so that the sampling pipe 7 connected to the weighing container 6 is driven by the vertical movement of the weighing container 6, so that sampling is performed. Each measuring means 6c by the pipe 7
It does not interfere with the measurement by.

Electromagnetic on-off valve 3b of the hopper scale 3 described above.
The above-mentioned pre-foaming machine control board 10 for controlling the above is provided.
Based on the signal from a, the electromagnetic opening / closing valve 3b is controlled so as to supply a predetermined weight of raw material to the pre-foaming machine 1.

Separately, a multiple measuring device control panel 11 for controlling the blow pipe control valve 8a of the sampling blow pipe 8 is provided, and the multiple measuring device control panel 11 starts when the sampling operation procedure starts. The pre-expanded resin particles in the storage hopper 5 can be conveyed to the measuring container 6 through the sampling tube 7 by controlling the above.

Further, the multiple measuring device control panel 11 is provided with timers T ₁ and T ₂ for timing the sampling operation, respectively, and as described above, the pre-foaming resin in which the pre-foaming is completed in the pre-foaming machine 1 is completed. Particles are exhaust hatch 4
When discharged from the storage hopper 5, the timer T
₁ (setting time 0 to 999 seconds) is activated, and when the timer T ₁ is activated, the blower pipe control valve 8a is closed to stop the blown air from the sampling blower pipe 8 to the sampling pipe 8 and thereby the measuring container 6 No pre-expanded resin particles are filled therein.

In addition, the multiple measuring device control panel 11 closes the weighing container damper 6b after the timer T ₁ is finished and starts the timer T ₂ (setting time 0 to 99 seconds) to start the weighing container. 6 is filled with the pre-expanded resin particles at a predetermined pressure, and when the timer T ₂ is finished, the blower pipe control valve 8a is controlled, and the sampling time for filling the pre-expanded resin particles into the measuring container 6 for a predetermined time by the timer T _2. Can be set.

Further, the multiple measuring device control panel 11 measures the weight of the pre-expanded resin particles filled in the measuring container 6 having a predetermined capacity at a predetermined pressure based on a signal from each measuring means 6c. The actual expansion ratio of the pre-expanded resin particles is converted from the weight and the capacity of the measuring container 6 described above. The empty weight of the weighing container 6 is measured in advance, and the empty weight is previously input to the multiple measurement device control panel 11.

The multiple measurement device control panel 11 compares the above conversion result with the preset pre-expansion multiples from the pre-expansion machine control panel 10 to calculate the difference between them, and obtains the setting error inputted in advance. A signal is output to the control panel 10 of the pre-foaming machine by judging the difference.

That is, when the above-mentioned difference is included in the range of the setting error, the multiple measuring device control panel 11 adjusts the amount of the next raw material to be the same as the amount of the previous injection so that the pre-exposure machine has the same amount. When a control signal is output to the control panel 10 and conversely the above difference is not included in the range of the setting error, the previous input amount is changed from the above difference by a predetermined calculation formula, and the changed value is changed. A control signal is output to the pre-foaming machine control panel 10 so that is the next input amount of the raw material.

Furthermore, the multiple measuring device control panel 11 controls the damper 6b for the weighing container so that the pre-expanded resin particles in the weighing container 6 are returned to the storage hopper 5 after the weighing in the weighing container 6 is completed. It is like this.

Further, the multiple measuring device control panel 11 has a structure shown in FIG.
As shown in FIG. 3 and FIG. 3, two rotary click type switches 11a for respectively inputting and displaying the effective volume of the pre-foaming machine 1 and the set pre-foaming multiple are provided, and the current and next raw material input amounts Two display parts 11b for displaying (kg) respectively are attached, and a multiple display part 11c for displaying the actual pre-foaming multiple obtained by sampling, and the pre-foaming multiple are the above-mentioned pre-foaming multiples. Is provided with a change amount display portion 11d for displaying the change amount (kg) of the raw material input when a predetermined error range is exceeded.

Further, the multiple measuring device control panel 11 is provided with variable switches 11e for setting and displaying the timers T ₁ and T ₂ , respectively, and further, the current temperature of the pre-foaming machine 1 and the progress thereof. A display unit 11f for displaying the time and the like, and a printer 11g for printing and outputting the pre-foaming result on a sheet 11h as shown in FIG. 4 are provided. The printing items on the printer 11g include foaming date and time, foaming type abbreviation code, raw material input amount at each time, measured foaming multiple at each time, foaming weight integrated value, and the like.

On the other hand, on the prefoaming machine control panel 10, as shown in FIG. 1, a measurement result display section 10a for displaying the measured input amount of the raw material, and a start key 10 for instructing the start of prefoaming.
Although not shown, a numeric keypad used for inputting various set values, a stop key for instructing the end of pre-foaming, and the like are provided.

Next, using the pre-foaming machine of the above embodiment,
A method for automatically correcting and controlling the foaming multiple of the pre-foamed resin particles will be described with reference to the flowcharts of FIGS. 5 and 6. First, the operator sets the volume of the weighing container 6 on the multiple measuring device control panel 11. , 30 L, effective capacity of the pre-foaming machine 1, eg 350 L, sampling air duct 8
Sampling start time after the start of, for example 60 seconds, sampling time, for example 30 seconds, set pre-expansion multiple (20 ~ 100
X), for example, 50 times, and a setting error and the like are set and input (step 1, hereinafter step is abbreviated as S).

Based on this, the multiple measurement device control panel 11
Thus, the input amount of the raw material corresponding to the set pre-expansion multiple and the effective volume of the pre-expansion machine 1 is calculated (S2), and the input amount is displayed as, for example, 350 / 50.0 = 7.0 kg (S3). At this time, if there is an experience value due to the habit of each device, the operator adjusts and inputs the input amount (S4).

Subsequently, the pre-foaming machine 1 is started by the pre-foaming machine control panel 10 (S5), the raw materials are weighed (S6), charged into the pre-foaming machine 1 (S7), and then heated by steam or the like. (S8). By this heating, the pre-foaming of the raw material is started and the bulk of the raw material is increased, and when the level meter 1c detects the end of the pre-foaming by the pre-foaming machine control panel 10 (S
9), the discharge hatch 4 is opened, and the pre-expanded resin particles are discharged into the storage hopper 5 (S10). At this time, a trigger signal for the sampling operation is output to the multiple measurement device control panel 11.

Next, the multiplex measuring device control panel 11 starts the timer T ₁ and closes the blower pipe control valve 8a for a set time, for example, 60 seconds to blow air from the sampling blower pipe 8 to the sampling pipe 8. By stopping, the pre-expanded resin particles are not filled in the measuring container 6 and the filling waiting time is set.

After that, when the timer T ₁ ends, the damper 6b for the measuring container is closed, and the pre-expanded resin particles are fed into the measuring container 6 at a predetermined pressure, for example, compressed air pressure of 3 kg / cm ² , and sampling is performed. At the same time as starting (S11), the timer T ₂ is started. When the timer T ₂ reaches a set time T _S, for example, 30 seconds and ends (S12), the sampling blower tube 8 and the blower tube control valve 8a are controlled to stop the conveyance of the pre-expanded resin particles, and thereby the preliminary operation is completed. The expanded resin particles are conveyed and filled only for a predetermined time.

Then, the weight of the weighing container 6 is measured by each of the weighing means 6c, and the weight of the pre-expanded resin particles in the weighing means 6c, for example, 622 g is measured (S13). Then, the foaming multiple, for example, 48.2 times is converted from the weight and the volume of the measuring container 6 (S14), and the foaming multiple is displayed.

At this time, the converted foaming multiple and other foaming conditions, such as the amount of raw material input, are printed and output by the printer 11g as shown in FIG. 4, for example. Then, from the above conversion foaming multiple, by a predetermined preset calculation formula, for example, 7.0 kg × (48.2 / 50.0) ≒ 6.7 kg
The raw material input amount corrected as described above is calculated.

This calculated value is displayed as the next raw material input amount on the display section 11b of the multiple measurement device control panel 11, and
The raw material input amount, the measured foaming multiple, and the like are printed by the printer 11g, and a control signal indicating the corrected raw material input amount is output to the prefoaming machine control panel 10 (S15).

On the other hand, since one batch of pre-foaming is completed in S10, a plurality of batches of continuous pre-foaming (initial value zero, set foaming number X) is set (S1).
6), 1 at the number of pre-foaming so far at the batch counter
(S17), the total number of foaming times and the set number of times X are compared (S18), and when the total number of foaming times is smaller than X, the process proceeds to S6, until the total number of foaming of the batch counter reaches the set number of times X, Repeat the above prefoaming cycle.

After that, when the total number of foaming in the batch counter becomes X, it is judged whether or not there is foaming in another silo (S19), and if there is foaming in another silo, further,
It is determined whether or not the foaming multiple has been changed (S20). If there is a change, the process proceeds to S1, and if there is no change, the process proceeds to S6. If it is judged in S19 that there is no foaming in another silo, the foaming is ended (S21) and the pre-foaming machine 1 is stopped (S2).
2), the pre-foaming operation is completed.

Thus, the pre-expanded resin particles of the above example
In the foaming multiple control device , the actual measurement of the prefoaming multiple by sampling the obtained prefoamed resin particles or the like is automatically and quickly performed by the multiple measuring device control board 11, so that the operator is required to blow the steam pressure, It is possible to obtain the pre-expanded resin particles having a desired expansion ratio, only by setting the set pre-expansion multiple and the allowable error, without considering the factors for varying the pre-expansion conditions such as the compounding agent type of the raw material.

From the above, the pre-expanded resin particles
The foaming multiplex control device greatly simplifies the operator's operation, can be automated, and can be unmanned.

By the way, conventionally, since the pre-expanded resin particles are scooped and filled in the measuring cup by hand so that the upper surface of the pre-expanded resin particles is flush with the upper end of the measuring cup, the pre-expanded resin particles are The packing rate of particles easily fluctuates,
Since the measurement error becomes large, the foaming multiple of the pre-foamed resin particles converted is also unstable.

However, of the above-mentioned pre-expanded resin particles,
The foaming multiple control device includes the storage hopper 5 and the weighing container 6 described above.
, And the pre-expanded resin particles are filled with the sampling blower pipe 8 at a predetermined pressure, so that they can be filled more quickly, uniformly, and densely than in the conventional case . Can be more efficient
In addition, the filling amount can be stabilized, and the measurement error in detecting the prefoaming multiple can be reduced.

By the way, the expansion ratio of the pre-expanded resin particles may vary by about 5% between the upper layer, the middle layer and the lower layer in one batch of the pre-expanding machine 1, but the same expansion ratio between batches, for example, in the middle layer. Changes little.

Therefore, the generation of the above-mentioned pre-expanded resin particles
In the foam multiple control device , the pre-expanding machine 1 for pre-expanding resin particles is used.
Since the sampling start time and the sampling time are controlled to be constant from the time of discharge from, the sampling site in one batch of the prefoaming machine 1 can be stabilized, and the measurement error can be reduced.

Therefore, the expansion ratio of the above pre-expanded resin particles
The measurement accuracy of the weighing method in the number control device was investigated. First, pre-expanded pre-expanded resin particles having an expansion ratio of 62 times (dry product) were repeatedly sampled and measured in the same manner 10 times by the above-described multiple measurement method, and the accuracy was calculated from each measured value and the conversion multiple. .

At this time, as the condition of the apparatus, the measuring container 6
The capacity was 30.64 L, four strain gauge type load cells (maximum weight value 20 kg) were used as the weight measuring means 6c, and the compressed air pressure of the sampling air duct 8 was 3 kg / cm ² .

The results of this measurement are shown in Table 1. As is clear from this result, ± 2.5S (probability 99%) with respect to the average value m
The foaming ratio included within is 59.6 to 62.4 times, ± 2.5S
Since the accuracy was /m=±2.3%, the accuracy was good with little variation.

[0056]

[Table 1]

Next, in order to further improve the sampling accuracy, the strain gauge type load cell (maximum weighing value 20 kg) as the weighing means 6c is replaced with a maximum weighing value 10 kg.
Similarly, four strain gauge type load cells were used, and instead of the 62-fold pre-expanded resin particles, the 59-fold product was used, and the sampling measurement was performed 10 times under the same conditions as above. The results are shown in Table 2.

As is clear from this result, the range of the measured value of the dried product is 520 to 530 g and 10 g, but when converted to a multiple, it is 57.8 to 59.9 times, which is 1.1 times the range. ± 2.5S for the average value m (expansion ratio included in probability 99%) is 52.7
It was up to 59.2 times, and the accuracy was ± 2.5 S / m = ± 1.6%, which showed good accuracy with less variation.

This is because the total weight of the pre-expanded resin particles for sampling, the weighing container 6 and the like does not exceed 10 kg, and the strain gauge type load cell as the weighing means 6c has a maximum weighing value of 10 kg. It is considered that this is due to the reduction in the measurement error of the strain gauge type load cell, since the strain gauge type load cell improves the measurement accuracy as it approaches the maximum value.

[0060]

[Table 2]

Next, the pre-expanded resin particles to be pre-expanded contain water by the steam for heating, and about 59% of the above-mentioned 59 times product (dry product) was added to make a sample. Similarly, the above sample was repeated 7 times for sampling and weighing. The results are shown in Table 3. Further, the same sample was repeatedly sampled and weighed eight times by the cup weighing by the operator, and the foaming multiples of each were converted. Table 4 shows the results.

As is clear from the results shown in Table 3, the range of measured values of the water-containing product is 568 to 580 g and 12 g, which is 52.7 to 53.9 times, which is 1.2 times the range when converted to a multiple. In addition, ± 2.5S (99%) for the average value m was 52.2 to 54.7 times, showing an accuracy of ± 2.5S / m = ± 2.3%. Although a slight decrease in precision was observed, it showed good precision with little variation in practical use.

On the other hand, as shown in Table 4, the width of the foaming multiple in the cup weighing by the operator is 52.1 to 55.4 times, which is 3.3 times the width. Also, ± 2.5S for the average value m
The (foaming multiple within the range of 99% probability) was 51.0 to 56.2 times, and the accuracy of ± 2.5 S / m = ± 4.9% was shown. Therefore, the weighing method in this example is more accurate at a predetermined pressure. It became clear that the filling can be performed uniformly and densely, the filling error can be reduced, and the weighing accuracy is excellent.

[0064]

[Table 3]

[0065]

[Table 4]

Next, using the 59-fold product containing the above water, the air pressure of the compressed air in the sampling air duct 8 is set to 3
When sampling / weighing was performed instead of 2 kg / cm ² from kg / cm ² , the measured value was 562 g and the converted foaming multiple was 54.5. Furthermore, when the sampling air pressure of the compressed air in the sampling air duct 8 was changed from 3 kg / cm ² to 1 kg / cm ² , the measured value was 544 g, and the converted foaming multiple was 56.3.
Met.

When the air pressure was changed as described above and the filling in the measuring container 6 was observed, when the compressed air in the sampling air duct 8 had an air pressure of 3 kg / cm ² , it was filled in about 20 seconds. At 2kg / cm ² , about 25 seconds, 1kg / c
m ² was about 35 seconds, and the visual observation of the filling state of the measuring container 6 showed that the filling property was good at 3 kg / cm ² and 2 kg / cm ² , and the filling at 1 kg / cm ² was poor. . 4kg / c
At m ² or more, the pre-expanded resin particles were sometimes deformed.

[0068] From these results, the air pressure of the sampling blower tube 8 may be used in the range of 1.5 ~3.5 kg / cm ^2, further the range of 2-3 kg / cm ² was considered optimal.

Next, a control method for correcting the water content in the pre-expansion and calculating the pre-expansion multiple in the dried product will be described. First, a predetermined amount of pre-expanded resin particles having various expansion ratios immediately after foaming were sampled in a fixed amount as described above, and the result of converting the expansion ratio by measuring the weight, drying the pre-expanded resin particles, and sampling again, Similarly, when compared with the result obtained by converting the expansion ratio, the water content of the pre-expanded resin particles immediately after expansion was about 3% on average.
However, the above-mentioned water content is an apparent water content because the filling rate is different between the dry product and the undried product because the filling property into the measuring container is different.

Therefore, when the moisture contents of the same amount of the dried product and the undried product were accurately measured and compared, the moisture content of the undried product was about 7%. That is, 4% is offset by the difference in filling property.

Therefore, if the apparent water content is corrected, even the pre-expanded resin particles which are undried products immediately after foaming can be provided with a foaming multiple almost equal to that of the dried product, which is useful for the subsequent foaming process. Is. Therefore, the water content can be corrected, for example, by adding 3% to the capacity set value in the measuring container 6 or the multiple measurement device control panel 11 of the pre-foaming machine 1.

However, such correction is effective if the pre-foaming machine 1 and the raw material used have a predetermined range, but if the pre-foaming machine 1 and the raw material used are out of the predetermined range,
Since the correction value also needs to be changed, it is not particularly limited to the above correction value.

In addition, the generation of the pre-expanded resin particles of the above example
In the bubble multiple control device , the measurement by the measuring container 6 is completed,
An example was given in which the raw material was added next time after converting the foaming multiple and calculating the correction value.However, if the difference between the converted foaming multiple and the set foaming multiple in each batch is within the predetermined range, after the raw material is added. Alternatively, the raw material charging may be controlled so that the next raw material is immediately charged at the previous raw material charging amount. This allows
Since it is possible to reduce the waiting time for completing the raw material charging in the continuous production in the batch type prefoaming machine 1, the prefoaming in the continuous production can be accelerated.

[0074]

As described above, the apparatus for controlling the expansion ratio of the pre-expanded resin particles of the present invention is a pre-expansion machine for supplying the raw material and pre-expanding it based on the input pre-expansion multiple.
And collect the pre-expanded resin particles discharged from the pre-expanding machine.
The storage hopper to be stored and the above-mentioned storage hopper.
And a damper that can open and close the opening on the bottom surface
Below the weighing container of the specified capacity and the storage hopper
Part that communicates between the upper part and the side surface of the measuring container.
Ring and pre-expanded resin particles discharged to the above storage hopper
Transport the child to the weighing container via the sampling tube
To send compressed air to the sampling tube for filling
Weigh the air duct for sampling and the weighing container above.
And the pre-expanded resin particles in the measuring container.
Controls the sampling operation for filling and
The weight of the pre-expanded resin particles measured by the measuring means and
Change the expansion ratio of the pre-expanded resin particles from the volume of the measuring container.
It is a configuration provided with a multiple measurement device control panel for calculation.

Therefore, in the above configuration, the pre-foamed resin particles discharged from the pre-foaming machine can be conveyed by, for example, compressed air or the like, and directly filled from the storage hopper into the measuring container. Easy measurement of prefoaming multiple
Therefore , the operator only needs to set the preset pre-expansion multiple, and the operation of the operator can be greatly simplified.

Further, in the above structure, the storage hopper is
Since the pre-expanded resin particles are filled into the weighing container at a predetermined pressure, the filling can be performed more uniformly and quickly compared to the conventional weighing method, and the work efficiency can be improved.
In fact, the filling amount can be stabilized. Therefore,
Since it is possible to reduce the measurement error when detecting the pre-expansion multiple, it is possible to stabilize the expansion factor of the obtained pre-expanded resin particles.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an expansion ratio control device for pre-expanded resin particles of the present invention.

FIG. 2 is a configuration diagram of a multiplex measuring device control panel in the foaming multiplex control device.

FIG. 3 is a front view of the control panel of the multiple measurement device.

FIG. 4 is a front view of a main part of a print sheet on which a result of pre-foaming is printed and output from the control panel of the multiple measurement device.

FIG. 5 is a first half of a flowchart showing a method for controlling the expansion ratio of the pre-expanded resin particles.

FIG. 6 is the second half of the flowchart showing the method for controlling the expansion ratio of the pre-expanded resin particles.

[Explanation of symbols]

 1 Pre-foaming machine 6 Measuring container

Claims (1)

(57) [Claims] 1. A pre-expansion resin particle expansion ratio control device for controlling the pre-expansion ratio of the pre-expanded resin particles when pre-expanding a raw material composed of synthetic resin particles in a pre-expansion machine. In, the raw material is supplied based on the set pre-expansion multiple
A pre-foaming machine for pre-foaming and a pre-foamed resin particle discharged from the pre-foaming machine are stored.
And a storage hopper that is disposed above the storage hopper,
It has a damper that can open and close the opening
Connect the weighing container to the bottom of the storage hopper and the upper side of the weighing container.
The sampling tube that passes through and the pre-expanded resin particles discharged to the storage hopper are added to the above-mentioned support.
Transport it to the above measuring container through a sampling pipe and fill it.
For sending compressed air to the sampling tube
Blower pipe, measuring means for measuring the weight of the measuring container, and a sampler for filling the measuring container with pre-expanded resin particles.
Control the operation of the
The weight of the pre-expanded resin particles and the volume of the measuring container
Measuring device for converting the expansion ratio of pre-expanded resin particles
An expansion ratio control device for pre-expanded resin particles, comprising a control board .