JPH05285954A - Plastic molded raw material weighing and feeding device - Google Patents

Abstract

PURPOSE:To weigh the amount of widely varying range in a short time by stopping a feeder at the time of the following feeding, weighing the weight of a discharged material by the given count value and opening a discharge dumper. CONSTITUTION:A transmitter 17 for issuing signals to a feeder 10 for every one count, a control device 30 for stopping the feeder 10 by the given count value, a weighing means 22 disposed below a discharge outlet 15 of the feeder 10 for weighing the weight of the discharged material and a receiving container 21 with a discharge dumper 23 are installed in a device. The control device 30 computes the weight of the discharged material per count based on the given count value until stopping and the weight value by the weighing means 22, and also computes the count value for stopping the feeder 10 in the following feed based on the weight per one count obtained by said computation and the given feed weight for the following feed. The feeder 10 is stopped in the following feed by the given count value obtained by said computation, and the weight of the discharged material is weighed, and then the discharge dumper 23 is opened and the material is discharged, and then the discharge dumper 23 is closed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a main raw material for plastics of powders and granules used as a raw material in molding such as injection molding and extrusion molding of plastics, and various powder and granule auxiliary materials such as colorants and additives. A device for weighing and supplying one raw material to a molding machine.

[0002]

2. Description of the Related Art The same kind of equipment has been used for the following purposes: (a) Controlling the main material consumption of each molding machine over a long period (second,
(Hour, not minute) (b) Management of main material consumption of each molding machine in a short period (minute). For example, molded products in extrusion molding (eg pipes)
(C) Mixing a constant ratio of a plurality of raw materials The purpose (a) is the simplest and there is no particular problem in the prior art, and various known means can be used. For the purpose (b), a so-called loss-in-weight continuous weighing and feeding technique is mainly used, in which a raw material hopper having a feeder (for example, a screw) and a weighing means at the bottom is used to measure the time transition of the total weight reduction of the raw material hopper. Is used for. This method is intended (b)
There is no big problem with.

[0003]

However, in the object (c), there is a problem in the conventional technique. The background is listed as follows: (a) In the molding machine, it is necessary to keep the compounding ratio within a predetermined value and accuracy in a short time period of 10 seconds to 30 seconds at the maximum. This is more difficult than the purpose (b) in which minute order management is good.

(B) In many cases, the mixing ratio of the auxiliary raw material (for example, colorant) to the main raw material is extremely low. Therefore, the supply kg of the auxiliary raw material / hour is very small. For example, capacity 10kg /
At the time of molding, the coloring agent having a 1% compounding ratio has a small flow rate of 100 g / hour. 30 seconds is equivalent to a little less than 1 gram.

(C) When the colorant is mixed, for example, 0.5%
There is a wide range of variation from the level of about 10% to the blending amount, that is, the weighing amount.

[0006] In summary, in the case of blending the colorant, it is necessary to discuss the accuracy in a short time of 10 to 30 seconds, the amount per time is small, and moreover, the variation range of the weighing is wide. The above-mentioned loss-in-weight method is not suitable for weighing and supplying 100 grams / hour. Therefore, there is a technique of weighing a fixed amount in a batch type with various feeders by a hopper equipped with weighing means (hereinafter, referred to as "conventional way hopper"). In the conventional way hopper, at that time, the control device determines the time when the feeder is stopped by monitoring the weighing value from the weighing means. Even if the disassembling accuracy of the weighing means is good, the stopping accuracy of the feeder affects the weighing of batches.Therefore, for the purpose of improving the accuracy, the feeder's supply capacity should be large with most of the feed and the last with small capacity. To do this, or sometimes to use a medium power feed in the middle. The capability of these feeders is changed, for example, by changing the rotation speed using an inverter or switching to a different size or different type of feeder. The conventional way hopper is complicated and lacks flexibility, and is suitable for a dedicated machine having a constant weighed amount, but it leaves a problem for the purpose (c). A small amount of a few grams,
The size of the range of change and the technical conditions of weighing anywhere within that size in a short time have been problems.

Although the technique of Practical Registration No. 12669912 is a known technique in which the colorant is successfully blended under the above-mentioned conditions, it is merely a volumetric formulation, and the automatic operation by setting the weight ratio, the consumption amount, etc. The problem was that it was impossible to control the weight.

The present invention can be used without problems for weighing and supplying any of the above-mentioned required conditions, that is, the colorant and other additives and the main raw material in the case of blending the colorant. The aim is to create a weighing and supplying device that can weigh a wide range of changes of several tens of times in a short time, and that can perform automatic operation by setting the weight value and manage weight such as consumption.

[0009]

According to the plastic molding raw material weighing / supplying apparatus of the present invention, the feeder is provided with a transmitter for transmitting a signal for each count, which is a unit of a fixed rotation angle, and receives the count. A control device with a control unit for stopping the feeder at a predetermined count value is provided, and in order to measure the weight of the discharged product from the start to the stop of the feeder, a weighing unit and a discharge damper are placed below the discharge port of the feeder. A container is provided, and the control device calculates the weight per count of the discharged product based on a predetermined count value until the stop and the weight value from the weighing means,
A controller having a calculation unit for calculating a count value (the "predetermined count value") at which the feeder should be stopped in the next feed from the weight per count obtained as a result of the calculation and the predetermined feed weight for the next feed. Is equipped with a predetermined count value obtained as a result of the calculation, the feeder is stopped at the next feeding, the weight of the discharged product is weighed, the discharge damper is opened thereafter, and the discharge damper is closed after discharge.

Further, when the plastic molding raw material weighing / supplying device of the present invention is implemented, the control device, when there are a plurality of predetermined count values at which the feeder should be stopped, the feeder discharges at a count value smaller than the predetermined count value by a specific number. The calculation value is obtained from the weighing means, and the weight value per count of the discharge value is calculated based on the count value and the weight value to recalculate a predetermined count value at which the feed should be stopped. By adding parts,
It is also possible to obtain a discharge product having a more accurate weight.

The feeder used in the present invention is a positive-displacement feeder, but a feeder having a high supply amount accuracy is suitable. In addition, one rotation of the feeder is made plural at equal angles (for example, 10 or 30).
It is preferable that the discharge amount for each constant rotation angle unit is as uniform as possible when divided into units.

One rotation of the positive-displacement feeder having a very high supply accuracy is finely divided as described above to make one count, and as soon as a predetermined count signal is received by the control device, a mechanical, electromagnetic brake or other means is provided. It can be seen that, when the discharge is instantaneously stopped at the rotation angle position of the count, even if the weight of the discharged product is checked, a highly accurate result is obtained. Further, since the count value is the rotation angle itself, if a predetermined count is changed, an amount proportional to this can be obtained, and there is no influence of the sliding resistance of the feeder or the change of the drive motor input voltage. In this respect, it is different from the conventional way hopper in which the frequency (hertz) of the input current is changed and the rotation speed is indirectly operated but the absolute value of the rotation speed (for example, rpm) is not measured. Depending on the technology of the positive displacement feeder, this technical fact applies to a fairly wide range of raw material types. If a proper feeder is selected, it is often more accurate than a conventional way hopper, especially in the case of a small amount fixed amount discharge. Further, the discharge amount can be widely changed by changing the count value. In the case of a conventional way hopper that performs large feed, small feed, etc. by using the value of the weighing means by the control device and variously predicts the time at which the feeder should be stopped and stops the feeder, one weighing batch amount can be widely used. When designed so that the time required for one weighing is generally long. On the other hand, the feeder of the present invention ignores the weighing value from the weighing means during feeding, and the controller uniquely and momentarily stops the feeder at a predetermined count value, so that there is an extra amount near the feeder stop. Without taking a long time,
The experimental result that the weight accuracy of the discharge amount is also excellent was obtained.

When the plastic molding raw material is the object to be weighed and supplied, the case where the bulk specific gravity changes rapidly in a short time is as follows.
It may be excluded from consideration as a practical technique. The change in bulk specific gravity occurs only when there is a very gradual change, or when a manufacturer switches to a different raw material in the middle of the same species. On the basis of such an actual situation, the value of the constant amount supply of the positive displacement feeder by the instantaneous stop at the predetermined count value, which is one of the configurations of the present invention, is high. As in the conventional way hopper, even if the feeder is not stopped by the weighing value from the weighing means, the apparatus of the present invention that obtains a predetermined count value by using the previous weighing value is not only sufficient in accuracy. As described below, in the intended field of weighing and supply of the plastic molding raw material, the result is that a rather excellent secondary effect is produced.

That is, in the device of the present invention, the positive displacement feeder is stopped at the count value, but the control device feeds back the previous actual weighing value to determine the predetermined count value each time, and the weight is calculated. It is not a volumetric formula that was ignored. Further, after the feeder stops at the count value, the true discharge amount at this time is also accurately input to the control device as a weighing value. Therefore, various weight-based management and processes (compounding etc.) related to molding
Can be assembled. For example, the processing amount k in a short time period
By controlling the screw rotation speed of the extruder by extrusion molding by grasping the actual condition of g / hour, the thickness of the extruded product (for example, pipe) can be controlled. Further, it is naturally possible to control the cumulative consumption of raw materials within the range of accuracy of the weighing means. It also provides a means for solving a case that is difficult even in the formulation of molding raw materials, such as a minute amount of the colorant. That is, if the feeder is stopped with a small (for example, 1 or 2) count value, a very small amount is discharged to the receiving hopper, and the control device knows the true weighing value. In the case of an extremely small amount, there is a high rate that the true weighing value is considerably different from the target weighing value when the control device calculates the predetermined count value. However, if the main raw material side is also equipped with the weighing / feeding device of the present invention, the main raw material side has a high compounding ratio, that is, a large amount, and the predetermined count value for stopping is a large count value such as 70 to 100. Substantially matches the target weight value when calculated. Therefore, after the colorant is weighed and supplied, various measures can be taken, such as using the true weighted value of the colorant to calculate a predetermined count value in the main raw material side device, and weighing and supplying the main raw material amount.

[0014]

Embodiments of the present invention will be described below with reference to FIGS. In the drawings, the same members are denoted by the same reference numerals.

FIG. 1 is an overall side view of an embodiment of a plastic molding raw material weighing / feeding device according to the present invention. A weighing disk 12 is arranged at the bottom of the hopper 11 of the feeder 10. The weighing disk 12 is evenly distributed in the circumferential direction.
There are 0 weighing boxes 13 opened, and the disk is rotatably driven by a drive shaft (not shown) at the center, which is connected to a drive motor 16 with a speed reducer via a transmitter 17.
At that time, the raw material 18 is measured at a position where the shielding plate 14 is not provided.
Is discharged, the rotation progresses, and the liquid is discharged downward at the position of the discharge port 15. In the process, the transmitter 17 transmits a signal with high accuracy at each position where each of the measuring boxes 13 passes through the discharge port 15,
The control device 30 receives the count signal 31.

On the other hand, a weighing container and a receiving container 20 with a discharge damper are provided for the purpose of receiving the discharged matter from the feeder 10. The receiving container 21 is provided with weighing means 22 and a damper 23. The receiving container 21 is empty before the feeder 10 is activated, and the damper 23 is closed by the force of the spring 24.

After the feeder 10 is started, the control device 3
At the moment when 0 receives a predetermined count value, the control device 30 transmits a drive motor start / instantaneous stop signal 32, and the drive motor 16 is instantaneously stopped. Immediately after that, the control device 30 receives the weighing signal 33 from the weighing means 22, and then transmits an opening signal of the opening / closing signals 34 of the discharge damper to the damper opening mechanism 25, and the damper opening mechanism 25 resists the spring 24 and the damper opening mechanism 25. 23 is opened, and the discharge product in the receiving container 21 is discharged toward the next step 40 such as a molding machine raw material supply port.

The damper opening mechanism 25 is not in contact with the damper 23 or the receiving container 21 except when the opening / closing signal 34 of the discharge damper gives an open signal, that is, during the time period when the weighing means 22 needs to be operated.

Here, the control device 30 calculates the weight per count of the discharged product based on the predetermined count value until the stop and the weight value from the weighing means, and the weight per count and a predetermined feed value for the next feed. From the feed weight (which is set in the control device 30 by hand or by inputting a signal from the other), the count value for stopping the feeder at the next feed (the "predetermined count value") is calculated, and Handle as the feeder stop position.

FIG. 2 is a block diagram illustrating an example of the configuration of the control device 30 of the present invention. Two examples of the operation of FIG. 2 are shown in FIG.
And described later in FIG. The control device 30 includes a signal conversion unit 52 that receives the signal from the oscillator 17 and converts it into a signal that can be accepted by the counter, and a counter 59 that receives the converted signal. Further, there is a weight conversion unit 53 that receives the signal 33 from the weighing means 22 and converts it into a weighed value, and a weight setting unit 54 that can set the next feed weight manually or by an external signal (not shown). Next, in the arithmetic processing unit 55, an arithmetic unit 60 that calculates the weight per count of the discharged product based on the count value from the counter 59 and the weight value from the weighing means, and the weight and weight setting per count. There is a calculation unit 61 that calculates a predetermined count value for stopping the feeder at the next feed from the feed weight from the unit 54. Further, there is a count coincidence detection unit 62 which compares a predetermined count value from a calculation unit 61 which calculates a predetermined count value with a current count value from a counter 59 and transmits when the two match. Further, a data storage unit 56 is connected to the arithmetic processing unit 55, which responds to the necessity of temporary storage of the calculation result data, the weighing value, and the like. The control unit 57 in the control device 30 receives a signal from the operation switch 58 and a signal from the count coincidence detection unit 62, and transmits a start / instantaneous stop signal 32 for the feeder drive motor and an open / close signal 34 for the discharge damper. A reset, a calculation execution command, etc. are transmitted to the calculation processing unit 55.

FIG. 3 is a flow chart for explaining the most basic operation example of the control device 30. First, for simplification of understanding, a state of steady operation when the operation switch is ON will be described. Since the operation switch is ON (S1), the following cycle continues. Read the weight setting value (D) (S
2) Read the previous 1 count weight (C) (S
3) A predetermined count is calculated (S4). Next, the weight value is reset (S5) and the counter of the transmitter is reset (S5).
6) Then, the drive motor of the feeder is turned on (S7).
When the feeder continues to rotate and the number of signals from the transmitter reaches a predetermined count (E) (S8), the feeder drive motor is turned off (S9) and the rotation of the feeder is instantaneously stopped.

After the time required for signal stabilization from the weighing means has elapsed (S10), the count value (A) and the weighed value (B) are read (S11, S12), and one count weight (C) is calculated and stored (S13). ) Use as the next 1 count weight. For the next 1-count weight, a value obtained by a control calculation (average value in a simple example) based on the past 1-count weight may be used.

Thereafter, the discharge damper is opened / closed (S14 to S1).
7) Then, the raw material is discharged, and one cycle operation is completed. In the device of the present invention, since the past data of 1 count weight is not stored at the time of the first operation, it is necessary to take a means of compensating for the past data. There are various problems, and it is not an essential problem.

FIG. 4 is a flow chart for explaining another operation example of the control device 30. Differences from FIG. 3 will be described.

In the operation of FIG. 4, the feeder is stopped when the count value matches a predetermined count value (C) -K (K is a specific number such as 1). Thereafter, the additional count calculation: C1 = (D-B1) * A1 / B1 is performed. When the additional count (C1) is 1 or more, the feeder drive motor 16 is turned on again, and then the transmitter 1
When the count value of 7 reaches the additional count value, the feeder drive motor 16 is turned off and the rotation of the feeder is instantaneously stopped. This is an example used when there is a margin in the operation cycle time and higher accuracy is required. Further, in the case of the weighing means in which the time required for stabilizing the signal from the weighing means is short,
If certain conditions are met, such as a long time interval between counts and an intermittent falling state from the feeder, in the embodiment of FIG. 4, the "count value is a predetermined count value (C) -K (K When a certain number (such as 1) matches, the weighing value at that time may be read without temporarily stopping the feeder. 5 to 7 are views of the apparatus similar to FIG. 1 and show examples of other embodiments.

5 and 6 are elevation views of an embodiment in which another type is adopted as the feeder 10 of FIG. 6 is shown in FIG.
The AA cross section of is shown. The weighing disk 12 has a horizontal axis of rotation, that is to say the surface of rotation is vertical and has a weighing box 13 which is open to the outside of the circumference. Reference numeral 19 is the weighing disk 1.
2 shows the direction of rotation. The other points are the same as those in FIG.

FIG. 7 shows the embodiment of FIG. 1 and the feeder 1 of FIG.
The figure shows that the screw feeder unit 41 is replaced by 0. The other points are the same as in FIG. The screw feeder unit 41 increases the filling degree to improve accuracy, and
It is also preferable to make an inclined installation in a direction in which the outlet is high in order to prevent an unintended drop after the stop. It should be noted that the illustrated embodiment is for illustration and does not limit the content of the present invention.

[0028]

As described above, one rotation of the positive displacement feeder is finely divided as described above, and this is counted as one count. As soon as a predetermined count signal is received by the control device, it is mechanically or electromagnetically braked. In the case of instantaneous stop at the rotation angle position of counting, a fixed amount of discharge is performed with extremely high accuracy in terms of weight.

Further, if a proper feeder is selected, it is often more accurate than the conventional way hopper, especially in the case of a small amount fixed amount discharge. Further, the discharge amount can be widely changed by changing the count value.

In the case of a conventional way hopper, if one weighing batch is designed to have a wide range, the time required for one weighing time is generally long. The weighing value is ignored, and the control device uniquely and momentarily stops the feeder at a predetermined count value, so that no extra time is taken near the stop of the feeder and the weight accuracy of the discharge amount is excellent.

When the plastic molding raw material is the object to be weighed and supplied, the case where the bulk specific gravity changes rapidly in a short time is as follows.
It may be considered that consideration is unnecessary based on technical experience. By taking advantage of this fact, various excellent effects were obtained.

One of the constitutions of the present invention, the value of a fixed amount of the positive-displacement feeder by instantaneous stop at a predetermined count value is high. As in the conventional way hopper, even if the feeder is not stopped by the weighing value from the weighing means, the apparatus of the present invention that obtains a predetermined count value by using the previous weighing value is not only sufficient in accuracy. As described below, in the intended field of weighing and supply of the plastic molding raw material, the result is that a rather excellent secondary effect is produced.

That is, in the apparatus of the present invention, the positive displacement feeder is stopped at the count value, but the control device feeds back the previous actual weighing value to determine the predetermined count value every time, and the weight is determined. It is not a volumetric formula that was ignored.

Further, after the feeder stops at the count value, the true discharge amount at this time is also accurately input to the control device as a weighing value. Therefore, various weight-based processes and management related to molding can be performed. For example, it is possible to control the screw rotation speed of an extruder by extrusion molding to control the wall thickness of an extruded product (for example, a pipe) by grasping the actual condition of the throughput of kg / hour in a short time zone.

Further, it is naturally possible to control the cumulative consumption of raw materials within the range of accuracy of the weighing means.

Further, the present invention provides a means for solving a case that is difficult even in the formulation of molding raw materials, such as the case of blending a minute amount of a colorant. That is, if the feeder is stopped with a small (for example, 1 or 2) count value, a very small amount is discharged to the receiving hopper, and the control device knows the true weighing value. In the case of an extremely small amount, there is a high rate that the true weighing value is considerably different from the target weighing value when the control device calculates the predetermined count value. However, if the main raw material side is also equipped with the weighing / feeding device of the present invention, the main raw material side has a high compounding ratio, that is, a large amount, and the predetermined stop count value becomes a large count value such as 70 to 100. Substantially matches the target weight value when calculated. Therefore, after weighing and supplying the coloring agent, the true count value of the coloring agent is used to calculate the predetermined count value in the main raw material side device.
Various means such as measuring and supplying the main raw material amount can be taken.

[Brief description of drawings]

FIG. 1 is an overall elevation view of a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a configuration of a control device 30 of the present invention.

FIG. 3 is a flowchart for explaining the most basic operation example of the control device 30 of the present invention.

FIG. 4 is a flowchart illustrating another operation example of the control device 30 of the present invention.

FIG. 5 is an elevation view of an embodiment in which the feeder 10 of the present invention adopts another type different from FIG.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 shows a screw feeder unit 41 adopted as the feeder 10 of the present invention.

[Explanation of symbols]

 10 ... Feeder 11 ... Hopper 12 ... Weighing disk 13 ... Weighing box 14 ... Shielding plate 15 ... Discharge port 16 ... Drive motor 17 ... Transmitter 20 ... Weighing means and receiving container with discharge damper 21 ... Receiving container 22 ... Weighing means 23 ... Damper 25 ... Damper opening mechanism 30 ... Control device 31 ... Count signal 32 ... Drive motor Starting / instantaneous stop signal 33 ... Weighing signal 34 ... Discharge damper opening / closing signal 40 ... Molding machine raw material supply port, etc. Next step 41 ... Screw feeder unit 52 ... Signal converter 53 ... -Weight conversion unit 54 ... Weight setting unit 55 ... Calculation processing unit 56 ... Data storage unit 57 ... Control unit 58 ... Operation switch 59 ... Counter 62 ... Count coincidence detection unit

Claims (2)

[Claims] 1. The feeder has a fixed rotation angle unit of 1
Provided with a transmitter for transmitting a signal for each count, provided with a control device having a control unit for receiving the count and stopping the feeder at a predetermined count value, and controlling the weight of the discharged product from start to stop of the feeder. For weighing, a weighing means and a receiving container with a discharge damper are provided below the discharge port of the feeder, and the controller controls the number of discharges per one count based on a predetermined count value until the stop and the weight value from the weighing means. A calculation unit that calculates the weight and the calculation result 1
It has a calculation unit that calculates the count value at which the feeder should be stopped at the next feed from the weight per count and the predetermined feed weight for the next feed, and the control unit uses the predetermined count value obtained as a result of the calculation at the time of the next feed. It is characterized in that after stopping the feeder, the weight of the discharged product is weighed, the discharge damper is then opened, and the discharge damper is closed after discharge.
Plastic molding raw material weighing and supply device. 2. The control device according to claim 1, wherein, when there are a plurality of predetermined count values at which the feeder should be stopped, the weighed value of the feeder discharge is measured by a count value that is a specific number less than the predetermined count value. From the means, and based on the count value and the weighing value, the weighing value of the discharged product is 1
A plastic molding raw material weighing / supplying device, further comprising an arithmetic unit for recalculating a predetermined count value at which feeding should be stopped by calculating a weight per count.