JPH0680816A - Apparatus for automatic determination of expansion ratio - Google Patents

Abstract

PURPOSE:To eliminate the error of determined expansion ratio caused by moisture and to enable smooth transfer of prefoamed particles in a pipe of an apparatus for the automatic determination of the expansion ratio of a prefoamed particles foamed in a batch prefoaming machine by drying the sampled prefoamed particles. CONSTITUTION:The objective apparatus is provided with a measuring vessel 46 capable of forming a measuring space 57 having a definite volume in the vessel, a filling feeder 47 to charge the measuring space 57 with a part of prefoamed particles 69 discharged from a batch prefoaming machine 31, a weighing device 48 to determine the weight of the prefoamed particles 69 supplied to the measuring space 57 and transmitting the measured value as an electric signal and a controller 55 for converting the electric signal transmitted from the weighing device 48 into the foaming ratio of the preformed particle 69, transmitting a controlling signal corresponding to the deviation of the converted value from a preset foaming ratio and adjusting the charging rate of the raw material to the prefoaming machine 31. An air-injector 52 and a drying vessel 53 are connected between the discharging side of the prefoaming machine 31 and the filling feeder 47 from the upstream side in the order and a dry-air supplying apparatus 54 is connected to the drying vessel 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic magnification measuring device for automatically measuring the expansion ratio of pre-expanded particles obtained by expanding expandable thermoplastic resin particles by a batch type pre-expanding machine.

[0002]

2. Description of the Related Art Conventionally, in the case of producing a foamed resin product using expandable thermoplastic resin particles as a raw material, the raw material particles are pre-expanded to a predetermined expansion ratio, and the pre-expanded particles are further expanded by a molding machine. I am molding the product by
There are two methods for pre-foaming: continuous method and batch method (so-called batch method). Compared to the continuous method, the batch method has less foaming unevenness of the pre-expanded particles, a homogeneous product can be obtained, and it is possible to quickly respond to the requirements of various kinds of pre-expanded particles. The formula method is generally adopted.

In the batch type pre-expanding method, first, a predetermined amount of raw material particles are supplied to a pre-expanding machine to be pre-expanded to a predetermined expansion ratio by a heating medium such as steam, and then the pre-expanded particles are batch type. Take it out. Next, the extracted pre-expanded particles are supplied to the molding machine via the aging silo, and a part of them is sampled in a container such as a bucket and weighed, and the weight is expanded according to a conversion table. Convert to magnification. Next, this conversion value is compared with a preset predetermined expansion ratio, and the predetermined expansion ratio is maintained by adjusting the supply amount of the heating medium or the raw material particles to the pre-expansion machine according to the deviation between both expansion ratios. Was there. However, in the above operation, all operations after sampling and sampling are done manually.

By the way, recently, the applications of foamed resin products have been varied from containers such as fish boxes and vegetable boxes to cushioning materials for home electric appliances, and various brands of raw material particles, particle sizes and expansion ratios are available according to the applications. In addition, the expansion ratio is strongly required to be accurate in order to stabilize product quality and improve productivity. However, even with the same expansion ratio, the brand of raw material particles,
The amount of raw material supplied changes depending on the particle size, and even with the same particle size,
Depending on the number of days from the production of the raw material particles to the foaming, the content of the foaming agent in the raw material particles changes with time, resulting in a difference in the foaming rate. The expansion ratio may change. Therefore,
Accurate measurement of the expansion ratio is essential to obtain an accurate expansion ratio.

However, conventionally, since the operations after sampling and sampling are manually performed, there is a problem that the obtained expansion ratio varies among individuals and that the expansion ratio changes depending on the volume and shape of the measuring container. Further, there is a problem that the measurement is labor intensive. The present inventor has developed an automatic measuring device for the expansion ratio in order to eliminate the above-mentioned problems, and has previously proposed it (Japanese Patent Application No. 3-185598).

The above automatic measuring device has a structure as shown in FIG. In FIG. 2, 1 is a pre-foaming machine, 2
Is an automatic measuring device.

This pre-foaming machine 1 is of a batch type (so-called batch type), in which a base 3 is provided with a foaming tank 4 and a discharging hopper 5 is attached to the discharge side of the foaming tank 4. Foaming tank 4
Is provided with a supply port 7 having a shut-off valve 6 in the upper part, a discharge port 9 having an air cylinder drive type lid 8 in the lower part, and an agitator (not shown) inside. Grain feeding hopper 5
Is provided with a sampling suction pipe 11 projecting below the sieving sieve 10 stretched inside, and a discharge port 1 at the bottom.
2, a granulation blower 13 is connected, and a recovery feeder 14 is provided on the upper part.

Further, the automatic measuring device 2 suspends the measuring container 16 and the filling feeder 17 in the case 15 by means of a weighing device 18 and an air cylinder 19, respectively, and the control device 2
0 is attached. The measuring container 16 is a cylindrical wire netting container, inside of which a rotary motor damper 21 is mounted so as to form a measuring space 22 having a constant volume above it, and a supply port 23 and a cleaning air port 24 at the upper part and a lower part. And a receiving hopper 25. The discharge port 26 of the receiving hopper 25 is connected to the recovery feeder 14 via a flexible tube 27. The filling feeder 17 is hung above and below the supply port 23 by an air cylinder 19 so as to be movable up and down and freely attached to and detached from the bottom of the supply port 23, and is connected to the suction pipe 11 via a flexible pipe 28. There is. The weighing device 18 is composed of a load cell or the like, and is adjusted so as to be 0 point when the inside of the measuring container 16 is empty. The control device 20 automates a series of operations from the measurement of the expansion ratio to the adjustment of the supply amount of the raw material particles to the foaming tank 4.

This automatic magnification measuring device 2 comprises a pre-foaming machine 1
It operates as follows when operating. First, the shutoff valve 6 is opened, a predetermined amount of the raw material particles 29 is supplied from the supply port 7 into the foaming tank 4 by the raw material particle supply device (not shown), and then the shutoff valve 6 is closed. Subsequently, a heating medium such as steam is blown into the foaming tank 4 to pre-foam the raw material particles 29 to a predetermined expansion ratio, and then the lid 8 is opened to pre-foam the particles 30 from the discharge port 9 to the inside of the particle feeding hopper 5. Then, the pre-expanded particles 30 that have been discharged to the molding machine and sized by the sieve 10 are supplied to the molding machine from the discharge port 12 by the blower 13 via the aging silo.

At this time, the signal from the controller 20 causes
The air cylinder 19 lowers the filling feeder 17 to bring it into contact with the bottom of the supply port 23 of the measurement container 16, and the filling feeder 17 samples a part of the pre-expanded particles 30 through the flexible tube 28 and the suction tube 11. , The measurement space 22 of the measurement container 16 is filled. When the filling is completed, the air cylinder 19 raises the filling feeder 17, and the supply port 23
Away from.

Next, the weighing device 18 measures the weight of the pre-expanded particles 30 in the measurement space 22 and sends the measured value to the control device 20 as an electric signal. The control device 20 is a scale 1
After storing the electrical signal from the hopper 2, the motor damper 21 is opened to receive the pre-expanded particles 30 in the measurement space 22.
5, and is collected in the granulating hopper 5 from the discharge port 26 via the flexible tube 27 by the collection feeder 14. Subsequently, compressed air is blown from the cleaning air port 24 to clean the inside of the measurement container 16, and the motor damper 21 is closed to prepare for the next measurement.

When the above operation is repeated a predetermined number of times, the control device 20 averages a plurality of measured weights to calculate the specific gravity of the pre-expanded particles 30, and converts the specific gravity into the expansion ratio. Then, the converted value is compared with a preset magnification that has been input in advance,
A control signal corresponding to the deviation between the two magnifications is transmitted to the raw material particle supply device. The raw material particle supply device receives the control signal and adjusts the supply amount of the raw material particles 29 used for the next pre-foaming, and then supplies the raw material particles 29 to the foaming tank 4. After that, the above series of operations is repeated.

[0013]

By the way, the raw material particles 2
9 is heated by a heating medium such as steam in the foaming tank 4 and foams, so that the resulting pre-foamed particles 30 contain moisture, and the degree of wetness thereof depends on the kind of the raw material particles 29, the expansion ratio, It varies from batch to batch depending on the heating time. Therefore, according to the automatic magnification measuring device 2 described above, an error may occur in the measurement magnification, or the pre-expanded particles 30 may be included in the flexible tube 2.
There was a problem that particles were not smoothly sent in the 8th. An object of the present invention is to improve the above automatic magnification measuring device 2 to eliminate the above-mentioned problems.

[0014]

In order to achieve the above object, the automatic magnification measuring device of the present invention comprises a measuring container in which a measuring space having a constant volume can be formed, and a preliminary discharge from a batch type prefoaming machine. A filling feeder for supplying a part of the expanded particles into the measurement space, a weighting device for measuring the weight of the pre-expanded particles supplied in the measurement space, and transmitting the measured value as an electric signal, and the meter. The electric signal from the weighting device is converted into the expansion ratio of the pre-expanded particles, and a control signal corresponding to the deviation between the conversion value and a preset predetermined ratio is transmitted to adjust the amount of raw material supplied into the pre-expansion machine. And a control device for controlling the temperature of the pre-foaming machine, the air injector and the drying container are sequentially connected from the upstream side between the discharge side of the pre-foaming machine and the filling feeder, and the drying air supply device is connected to the drying container. There is.

[0015]

In the automatic magnification measuring device having the above structure, the air injector samples and collects a part of the pre-expanded particles discharged by the pre-expanding machine and once supplies the pre-expanded particles into the drying container. The pre-expanded particles are dried in the dry container by the dry air blown from the dry air supply device, and then are supplied into the measurement space of the measurement container by the filling feeder. The pre-expanded particles dried in this way are smoothly transferred from the drying container to the measuring container, and at the same time, the error caused in the measurement magnification due to moisture is eliminated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows the overall configuration when the automatic magnification measuring device 32 of the present invention is applied to the pre-foaming machine 31. The pre-foaming machine 31 is of a batch type and has a base 33 provided with a foaming tank 34, and a granulating hopper 35 is attached to the discharge side of the foaming tank 34.

In the foaming tank 34, the raw material particles supplied from the upper supply port 36 are heated by a heating medium such as steam to pre-expand to a predetermined expansion ratio, and then the pre-expanded particles are discharged to the lower discharge port 37. It is to be discharged batchwise to the particle feeding hopper 35, has an agitator (not shown) inside, and has a shutoff valve 38 at the supply port 36 and an air cylinder drive type lid 39 at the discharge port 37.

The granulating hopper 35 receives the pre-expanded particles discharged from the foaming tank 34 and supplies the pre-expanded particles from the lower discharge port 40 to the molding machine through the aging silo. A sieve 41 for removing particles is stretched, a sampling suction pipe 42 is projected below the sieve 41, a granulation blower 43 is connected to the discharge port 40, and a recovery feeder 44 is provided on the upper portion. There is.

Further, the automatic magnification measuring device 32 has a case 4
5, a measuring container 46 and a filling feeder 47 are suspended by a weighing machine 48 and an air cylinder 49, respectively, and between the suction pipe 42 of the granulating hopper 35 and the filling feeder 47, a shut-off cock 50 from the upstream side in order. Ball cock 5
1, the air injector 52 and the drying container 53 are connected, the drying air supply device 54 is connected to the drying container 53, and the control device 55 is additionally provided.

The measuring container 46 is a cylindrical container made of a punching plate or a wire mesh, and a rotary motor damper 56 is installed therein so that it can be opened and closed so as to form a measuring space 57 having a constant volume (about 1 to 20 L) above it. In addition, a pre-expanded particle supply port 58 and a cleaning air port 59 are provided in the upper part, and a receiving hopper 60 is provided in the lower part. The receiving hopper 60 has a discharge port 61 at the lower end connected to the recovery feeder 44 of the grain feeding hopper 35 via a flexible tube 62. The motor damper 5
6 may be a slide type or the like.

The filling feeder 47 is arranged above the supply port 58 of the measuring container 46 so as to be moved up and down by an air cylinder 49, and is arranged at the bottom of the supply port 58 so as to be contactable and separable in order to eliminate a measurement error. It is connected to the bottom of the drying container 53 via a flexible tube 63. The weighing machine 48 is composed of a load cell or the like, and is adjusted in advance so as to reach 0 point when the inside of the measuring container 46 is empty. The shutoff cock 50 and the ball cock 51 are for drying the inside of the pipe upstream of the air injector 52, and the shutoff cock 50 is connected to a lower pipe branched from the upstream side of the ball cock 51. The air injector 52 samples a part of the pre-expanded particles discharged to the particle feeding hopper 35 through the suction pipe 42,
It is for supplying to the drying container 53, and its discharge side is connected to the upper part of the drying container 53.

The drying container 53 is a cylindrical container made of a punching plate or a wire mesh. A rotary motor damper 64 is attached to the bottom of the drying container 53 so as to be openable and closable, and is attached to the upper part of the grain feeding hopper 35. The motor damper 64 may be of a slide type or the like. The dry air supply device 54 is for supplying dry air having a temperature of room temperature to 70 ° C. to the drying container 53, and is installed by connecting the blower blower 66 and the heat exchanger 67 on the base 65 to perform heat exchange. The discharge side of the container 67 is connected to the bottom of the drying container 53. In some cases,
The heat exchanger 67 may be omitted.

The control device 55 is for automating a series of operations from the sampling and drying of the pre-expanded particles to the measurement of the expansion ratio and the adjustment of the supply amount of the raw material particles to the expansion tank 34.

Next, the operation of the above structure will be described. First, the ball cock 51 is closed and the deadline cock 50 is closed.
Then, compressed air is blown from the shutoff cock 50 and the air injector 52 to dry the inside of the pipe from the suction pipe 42 to the drying container 53 so that the pre-foamed particles are smoothly fed into the pipe. When the drying is completed, the dead cock 50 is closed and the ball cock 51 is opened.

Next, in the pre-foaming machine 31, the shut-off valve 38
And a predetermined amount of raw material particles 68 are supplied from the supply port 36 into the foaming tank 34 by a raw material particle supply device (not shown), and then the shutoff valve 38 is closed. As the raw material particles 68, polystyrene resin, polyolefin resin particles such as polyethylene and polypropylene, polyurethane resin particles and the like are used. Then, a heating medium such as steam is blown into the foaming tank 34 to pre-foam the raw material particles 68 to a predetermined foaming ratio, and then the lid 39 is opened to pre-foam the particles 69.
The pre-expanded particles 69 discharged from No. 7 into the granulating hopper 35 and rectified by the sieve 41 are supplied to the molding machine from the discharge port 40 by the granulating blower 43 via the aging silo.

At this time, in the automatic magnification measuring device 32, the signal from the control device 55 causes the air injector 5 to operate.
2 samples a part of the pre-expanded particles 69 through the suction pipe 42 and supplies the pre-expanded particles 69 into the drying container 53. The sampling amount is slightly larger than the amount required for measuring the expansion ratio. The reason for sampling with the air injector 52 is that if the sampling is performed with a blower or the like, the pre-expanded particles 69 contract and a difference occurs between the measurement magnification and the actual magnification. Then, the dry air supply device 54 blows dry air into the drying container 53 to dry the pre-expanded particles 69. The drying time is preferably about 10 to 30 seconds.

When the drying is completed, the air cylinder 49 lowers the filling feeder 47 and the supply port 58 of the measuring container 46.
The pre-expanded particles 69 in the drying container 53 are sucked by the required amount through the flexible tube 63 by contacting with the bottom of the container, and measured with a constant air pressure (0.5 to 3.5 kg / cm ² ). The measurement space 57 of the container 46 is filled with just enough.
When the filling is completed, the air cylinder 49 moves to the filling feeder 4
7 is lifted and separated from the supply port 58. The extra pre-expanded particles 69 remaining in the drying container 53 are collected in the particle feeding hopper 35 by opening the motor damper 64.

When the air cylinder 49 rises, the weighing device 4
8 measures the weight of the pre-expanded particles 69 in the measurement space 57 and sends the measured value to the control device 55 as an electric signal. After storing the electric signal from the weighing device 48, the control device 55 opens the motor damper 56, receives the pre-expanded particles 69 in the measurement space 57, and discharges them into the hopper 60.
The powder is collected from the No. 1 through the flexible tube 62 by the collection feeder 44 into the granulating hopper 35. Subsequently, compressed air is blown into the measurement container 46 from the cleaning air port 59 to clean the inside of the measurement container 46, and then the motor damper 56 is closed to prepare for the next measurement.

When the same operation as described above is repeated a predetermined number of times (for example, about three times), the control device 55 averages a plurality of measured weights from the weighting device 48 to calculate the specific gravity of the pre-expanded particles 69, and determines the specific gravity. Convert to foaming ratio. Subsequently, the converted value is compared with a predetermined set magnification inputted in advance, and when the deviation between both magnifications is ± 1 or more, a control signal corresponding to the deviation is sent to the weighing device of the raw material particle supplying device. Call. The weighing device, after receiving the control signal and adjusting the supply amount of the raw material particles 68 used for the next pre-expansion, supplies the same to the foaming tank 34, and
This supply amount is input to the control device 55 as an electric signal.

After that, the above series of operations are repeated, but since the control device 55 stores the latest corrected supply amount for the specific raw material particles 68 and the expansion ratio, the same raw material particles 68 and the expansion ratio will be used next time. When the pre-foaming is performed in step 1, the pre-foaming can be automatically performed under the same conditions. Further, by switching between the motor dampers 56 and 64, it is possible for one automatic magnification measuring device 32 to correspond to a plurality of pre-foaming machines 31.

As described above, in the automatic magnification measuring device 32 of this embodiment, the pre-expanded particles 69 are dried in the drying container 53, and the inside of the suction pipe 42 to the drying container 53 is also dried. The error generated in the measurement magnification is eliminated, and the pre-expanded particles 69 can be smoothly fed into the pipe.

[0032]

As described above, according to the present invention, a part of the pre-expanded particles discharged from the pre-expanding machine is sampled by the air injector and once supplied into the drying container, and the pre-expanded particles are supplied with the dry air. Since it is configured to dry with the dry air from the device, the error that occurs in the measurement magnification due to humidity is eliminated, not only can pre-foaming be performed with an extremely accurate expansion ratio, but also pre-expanded particles can be fed into the pipe. It has the advantage of being smooth. In addition,
As described in the examples, when the inside of the pipe from the pre-foaming machine to the drying container is dried, the pre-foamed particles can be more smoothly fed into the pipe.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment in which an automatic magnification measuring device of the present invention is applied to a batch type prefoaming machine.

FIG. 2 is an overall configuration diagram of an example in which a conventional (prior application) automatic magnification measuring device is applied to a batch type prefoaming machine.

[Explanation of symbols]

31 Pre-foaming machine 32 Automatic magnification measuring device 46 Measuring container 47 Filling feeder 48 Weigher 52 Air injector 53 Drying container 54 Dry air supply device 55 Control device 57 Measuring space 68 Raw material particle 69 Pre-foaming particle

Claims (1)

[Claims] 1. A measuring container capable of forming a measuring space having a constant volume therein, a filling feeder for supplying a part of the pre-expanded particles discharged from a batch type pre-expanding machine into the measuring space, and the measuring space. The weight of the pre-expanded particles supplied to the inside is measured, and a weighing device that transmits the measured value as an electric signal, and the electric signal from the weighing device is converted into the expansion ratio of the pre-expanded particles, and the converted value And a control device for transmitting a control signal according to a deviation from a preset predetermined scaling factor to adjust the amount of raw material supplied into the pre-foaming machine, and the discharge side of the pre-foaming machine and the filling feeder. An automatic magnification measuring device, characterized in that an air injector and a drying container are connected in sequence from the upstream side to a drying air supply device connected to the drying container.