JP7239101B2 - Granule feeder - Google Patents

Description

The present invention relates to a granular material supply device. More specifically, it relates to a granular material supply device for supplying granular material as a material to a subsequent molding machine.

2. Description of the Related Art Conventionally, there has been known a granular material supply device for supplying granular materials (powder and/or granules, hereinafter simply referred to as "granules") as materials to subsequent molding machines. This type of powder supply device is disclosed in Patent Document 1, for example.

The drying device (powder or granular material supply device) of Patent Document 1 is used to heat and dry the powder or granular material before being supplied to the subsequent molding machine, and then to supply the powder or granular material to the molding machine. The drying apparatus of Patent Document 1 includes a storage tank, a first exhaust port, an inlet, a first circulation pipe, a first airflow generating means, a heating unit, an exhaust pipe, a second exhaust port, a second 2 circulation pipes. A granular material as a material is stored in the storage tank. The first exhaust port is provided in the storage tank. The inlet introduces gas into the reservoir. The first circulation pipe connects the first exhaust port and the introduction port. The first airflow generating means generates an airflow in the first circulation pipe from the first exhaust port toward the introduction port. The heating unit heats the gas flowing through the first circulation pipe. The discharge pipe discharges the granular material downward from the storage tank. The second outlet is provided at the outlet. The second circulation pipe connects the second exhaust port and a connection port provided in the first circulation pipe. A portion of the gas in the reservoir flows through the discharge pipe to the second circulation pipe.

In the drying apparatus of Patent Document 1, part of the high-temperature gas in the storage tank flows through the discharge pipe to the second circulation path due to the configuration as described above. Therefore, it is considered that the temperature drop of the granular material in the discharge pipe can be suppressed.

Registered Utility Model No. 3208382

However, in the granular material supply device having the configuration described in Patent Document 1, the granular material before being supplied to the succeeding molding machine is supplied from the storage tank into the discharge pipe, and then in the discharge pipe. Temperature instability may occur during storage. For example, when the processing capacity of the molding machine is smaller than the retention amount of the powder or when the molding machine is stopped, the heat of the powder in the discharge pipe is transferred to the outside of the discharge pipe below the circulation path. There is a risk that the temperature of the powder or granular material will drop due to air being taken away. If the temperature of the granules before being supplied to the molding machine drops in the discharge pipe, the granules may absorb moisture again, degrading the material and leading to poor molding. , there was room for improvement. In addition to this, when the temperature of the granular material charged into the molding machine changes with time, the moldability may be adversely affected, which is not desirable. In order to prevent this, it is possible to provide a heat retaining structure or a temperature control mechanism, but that would increase the facility cost.

The present invention has been made in view of the above circumstances, and its object is to suppress the temperature change of the powder or granular material by the time it is put into the molding machine with a simple configuration, As a result, the granules are fed into the molding machine at a stable temperature, and molding defects are less likely to occur in subsequent molding machines.

In order to solve the above-mentioned problems, the first invention of the present application is a granular material supply device for supplying granular material to a subsequent molding machine, comprising a storage tank, a discharge pipe, a detector, and a supply amount adjustment. Provided is a granular material supply device including a mechanism and a controller. The storage tank stores the powder while maintaining the temperature above a certain level. The discharge pipe connects the lower end of the storage tank and the material inlet of the molding machine, and guides the powder from the storage tank to the material inlet according to its own weight. The detection unit detects the position of the upper surface of the area where the granular material accumulates in the discharge pipe. The supply amount adjustment mechanism is attached to the discharge pipe, and adjusts the amount of powder or grain supplied from the storage tank to the material inlet. The control unit controls the supply amount adjustment mechanism based on the detection result of the detection unit so that the retention time of the particulate material in the discharge pipe is within a predetermined time, and the detection unit It is attached to the lower side of the discharge pipe .
In a second invention of the present application, in the powdery material supply apparatus according to the first invention, a heat insulating structure is provided below the discharge pipe to suppress heat radiation of the powdery grains passing through the discharge pipe.
In a third invention of the present application, in the powdery or granular material supply device according to the second invention, the heat insulating structure includes an inner cylindrical portion and an outer cylindrical portion arranged radially outward of the inner cylindrical portion. Structure.

In a fourth invention of the present application, the powdery or granular material supply device according to any one of the first to third inventions further comprises a heating section for heating the granular material.

According to a fifth invention of the present application, in the granular material supply device according to the fourth invention, the heating unit heats the granular material inside the storage tank.

In a sixth invention of the present application, in the powdery or granular material supply device according to any one of the first invention to the fifth invention, the inner space of the storage tank and the inner space of the discharge pipe are filled with inert Gas is supplied.

In a seventh invention of the present application, in the powdery or granular material supply device according to any one of the first invention to the sixth invention, the internal space of the storage tank and the internal space of the discharge pipe are under atmospheric pressure. maintained at a higher pressure than

In an eighth invention of the present application, in the powdery or granular material supply device according to any one of the first invention to the seventh invention, the control unit adjusts the supply amount so that the residence time is within one hour. control the mechanism.

In a ninth invention of the present application, in the powdery or granular material supply device according to any one of the first invention to the eighth invention, the discharge pipe section includes an inner discharge pipe and an outer discharge pipe at least partially in the vertical direction. It is a multi-layered structure including a tube. The outer discharge pipe is arranged radially outward of the inner discharge pipe. The granular material passes through the inner space of the inner discharge pipe.

According to a tenth invention of the present application, in the granular material supply device according to any one of the first invention to the ninth invention, the supply amount adjustment mechanism has a slide shutter and a drive device. The slide shutter is movable between a closed position that closes the guide path for the particulate material in the discharge pipe and an open position that opens the guide path. The driving device slides the slide shutter.

In an eleventh invention of the present application, in the powdery or granular material supply apparatus according to the tenth invention, the discharge pipe is recessed radially outward from its inner peripheral surface, and the inner peripheral It has a recess with a decreasing distance from the facing side wall. The slide shutter at the open position is accommodated in the recess.

In a twelfth invention of the present application, in the powdery or granular material supply device according to any one of the first invention to the eleventh invention, the controller controls the supply amount adjustment mechanism to adjust the powder based on the detection result of the detector. When it is determined that the position of the upper surface of the granular material has not reached a predetermined position within a predetermined time after the granular material is supplied, it is determined that the granular material is not properly supplied, and an error is output.

According to the first to twelfth inventions of the present application, with a simple configuration, it is possible to suppress the temperature change of the powder or granular material before it is put into the molding machine, so that the powder can be supplied to the molding machine at a stable temperature. It is possible to make molding defects less likely to occur in the subsequent molding machine by charging the granular material.

In particular, according to the first invention of the present application, the residence time of the powder in the discharge pipe is set within a predetermined time. Therefore, it is possible to prevent the temperature of the granular material from becoming unstable before it is put into the molding machine.

In particular, according to the fourth invention of the present application, the temperature of the granular material can be kept constant at an appropriate temperature before being supplied to the subsequent molding machine. As a result, the occurrence of molding defects can be suppressed.

In particular, according to the fifth invention of the present application, the powder can be dried by heating in the storage tank before being supplied to the subsequent molding machine. Therefore, it is possible to make it more difficult for molding defects to occur.

In particular, according to the first invention of the present application, it is possible to accurately detect the timing at which the position of the upper surface of the area where the particulate matter accumulates reaches the inside of the discharge pipe. Therefore, the amount required for molding can be maintained while minimizing the amount of heat-dissipating powder.

In particular, according to the sixth aspect of the present application, it is possible to reduce the risk of deterioration of the powder particles due to oxidation or the like. Therefore, it is possible to make it more difficult for molding defects to occur.

In particular, according to the seventh invention of the present application, before being supplied to the subsequent molding machine, outside air is prevented from entering the storage tank or the discharge pipe, and the powder absorbs moisture from the outside air. It is possible to reduce the risk of being lost. Therefore, it is possible to make it more difficult for molding defects to occur.

In particular, according to the ninth invention of the present application, it is possible to prevent the heat of the granular material from being taken away by the outside air of the discharge pipe in the process of passing through the discharge pipe.

In particular, according to the tenth invention of the present application, it is possible to adjust the amount of powder or granular material supplied from the storage tank to the material inlet of the molding machine with an inexpensive configuration.

In particular, according to the eleventh invention of the present application, it is possible to form a recess, which is a region for retracting the slide shutter, with an inexpensive structure. In addition, powder particles are less likely to accumulate in the concave portions. Therefore, the granular material can be smoothly supplied to the molding machine.

In particular, according to the twelfth invention of the present application, when the supply of the granular material from the storage tank to the discharge pipe is delayed due to occurrence of bridging or the like, it is possible to recognize this by outputting an error.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the structure of the granular material supply apparatus which concerns on 1st Embodiment. FIG. 4 is a vertical cross-sectional view showing the configuration of the discharge pipe, level sensor, and supply amount adjusting mechanism, showing a state where the slide shutter is in the closed position; FIG. 4 is a vertical cross-sectional view showing the configuration of the discharge pipe, level sensor, and supply amount adjusting mechanism, showing a state where the slide shutter is at the open position; FIG. 3 is a block diagram showing the configuration of a control system of the granular material supply device; Fig. 3 is a flow chart showing the flow of processing performed when powder or granular material is introduced into the material inlet of the molding machine. It is a schematic diagram which shows the structure of the granular material supply apparatus which concerns on 2nd Embodiment. It is a flow chart which shows a flow of processing which a control part performs in a modification.

Exemplary embodiments of the invention are described below with reference to the drawings.

<1. First Embodiment>
<1-1. Overview of Granule Feeder>
First, a granular material supply device 100 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.

The granular material supply device 100 is a device for supplying granular material as a material to the subsequent molding machine 90 . The "granules" in this embodiment are resin pellets, more specifically resin pellets 9 for optical products, and more specifically polycarbonate pellets. The resin pellets 9 supplied from the granular material supply device 100 are molded in the molding machine 90 to form a transparent optical product such as a light guide plate. In the molding of transparent optical products, it is a particularly important quality control item to prevent defects such as discoloration caused by moisture absorption and the like. However, the granular material to be treated in the present invention is not necessarily limited to resin pellets for optical products.

Further, the "molding machine" in this embodiment is a molding machine for melting the resin pellets 9 and molding them into a predetermined shape (in this embodiment, the shape of an optical product), and is composed of, for example, an injection molding machine. can do. In the following description, it is assumed that the molding machine 90 is an injection molding machine. However, the molding machine 90 may be a known molding machine such as an extrusion molding machine other than the injection molding machine.

FIG. 1 schematically shows the configuration of a granular material supply device 100 according to the first embodiment. As shown in FIG. 1 , the granular material supply device 100 has a storage tank 10 , a supply section 20 , a circulation pipe 30 , a discharge section 40 and a control section 60 .

The storage tank 10 is a container that stores the resin pellets 9, which are powders as materials, while maintaining the temperature above a certain level. More specifically, the storage tank 10 of the present embodiment heats and dries the resin pellets 9 stored therein. As shown in FIG. 1, the storage tank 10 covers a substantially cylindrical side wall 11, a funnel-shaped bottom part 12 that gradually converges from the lower end of the side wall 11 toward the vertical downward side, and the upper part of the storage tank 10. and a top plate portion 13 . A space (internal space) for storing and drying the resin pellets 9 by heating is provided in the storage tank 10 . Note that the shape of the storage tank 10 may be other shapes. In addition, the storage tank 10 does not necessarily have to actively heat the internal space. Instead, for example, the resin pellets 9 stored therein may simply be kept at a certain temperature or higher.

A transport hopper 14 is installed at the upper end of the storage tank 10 . The transport hopper 14 is a container that temporarily stores the resin pellets 9 when the resin pellets 9 are supplied to the storage tank 10 . The transport hopper 14 is connected to the storage tank 10 via an openable/closable inlet 131 provided in the top plate portion 13 of the storage tank 10 . A downstream end of a transport pipe 21 (to be described later) is connected to the side of the transport hopper 14 .

The supply part 20 is a piping part for supplying the resin pellets 9 before heat drying into the storage tank 10 . As shown in FIG. 1 , the supply section 20 of this embodiment has a carrier pipe 21 and an exhaust pipe 22 . A downstream end of the transport pipe 21 is connected to a side portion of the transport hopper 14 . The upstream end of the exhaust pipe 22 is connected to the vertically upper end of the transport hopper 14 . A punching metal plate 141 is provided at the connecting portion between the conveying hopper 14 and the exhaust pipe 22 . The punching metal plate 141 has a plurality of through-holes that restrict passage of the resin pellets 9 and allow passage of gas.

When supplying the resin pellets 9, an air flow is generated inside the carrier pipe 21 and the exhaust pipe 22 by means of a force generating means such as a blower (not shown). Specifically, as indicated by arrows A1 and A2 in FIG. 1, an air current is generated from the conveying pipe 21 to the exhaust pipe 22 through the conveying hopper 14 . Then, the resin pellets 9 are conveyed from the material supply source provided upstream of the conveying pipe 21 to the conveying hopper 14 through the conveying pipe 21 . At this time, the movement of the resin pellets 9 from the transport hopper 14 to the exhaust pipe 22 is blocked by the punching metal plate 141 . Therefore, the resin pellets 9 are stored in the transport hopper 14 without flowing into the exhaust pipe 22 .

After the resin pellets 9 are stored in the transport hopper 14, the transport of the resin pellets 9 is stopped and the input port 131 is opened. thrown in. Thus, the supply unit 20 repeats the pneumatic transportation of the resin pellets 9 to the transportation hopper 14 and the opening of the input port 131, thereby intermittently supplying the resin pellets 9 (batch supply) )do.

However, the method of supplying the resin pellets 9 to the storage tank 10 does not necessarily have to be such a batch supply. For example, the resin pellets 9 may be continuously supplied into the storage tank 10 by an input method using another supply device or the like. Moreover, in the case of pneumatic transportation, not only suction but also positive pressure transportation may be used. Alternatively, the operator may directly put the resin pellets 9 into the storage tank 10 .

The circulation pipe 30 is a pipe for circulating gas in order to supply hot air for drying into the storage tank 10 . One end of the circulation pipe 30 is connected to an exhaust port 132 provided on the top plate portion 13 of the storage tank 10 . The other end of the circulation pipe 30 penetrates the side wall 11 of the storage tank 10 and is connected to a hot air inlet 34 arranged inside the storage tank 10 .

A filter 31 , a blower 32 , and a heater (heating section) 33 are provided in the course of the circulation pipe 30 . When the blower 32 is operated, an air current is generated in the circulation pipe 30 from the exhaust port 132 toward the hot air inlet (heating section) 34 as indicated by arrow A3 in FIG. Fine dust sucked from the storage tank 10 into the circulation pipe 30 is collected by the filter 31 . Also, the gas that has passed through the filter 31 is heated by the heater 33 to become hot air. Then, the hot air is introduced into the storage tank 10 from the hot air inlet 34 .

The hot air blown out from the hot air inlet 34 passes through the gaps between the resin pellets 9 stored inside the storage tank 10 and diffuses into the storage tank 10 . As a result, the resin pellets 9 are heated, moisture is evaporated from the resin pellets 9, and the resin pellets 9 are dried. That is, the gas diffused into the storage tank 10 removes moisture from the resin pellets 9 . Also, the moisture-absorbed gas rises in the storage tank 10, passes through the exhaust port 132 from the storage tank 10, and is sucked into the circulation pipe 30 again.

In addition, a ventro for releasing moisture-absorbed gas to the outside may be provided in the middle of the route of the circulation pipe 30 . Further, an adsorber that adsorbs moisture contained in the gas may be provided in the course of the circulation pipe 30 .

The discharge part 40 is a part for supplying the resin pellets 9 maintained at a constant temperature or higher from the storage tank 10 to the material inlet 90 a of the molding machine 90 in a timely manner. The discharge part 40 has a discharge pipe 41 as a main component.

The discharge pipe 41 is a pipe that connects the lower end of the storage tank 10 and the material inlet 90 a of the molding machine 90 . The discharge pipe 41 guides the resin pellets 9 from the storage tank 10 to the material inlet 90a of the molding machine 90 according to its own weight. As will be detailed later, the discharge pipe 41 has a partially double structure.

As shown in FIG. 1 , molding machine 90 has cylinder 91 , screw 92 and motor 93 . The cylinder 91 has a tubular shape extending in the horizontal direction. A material inlet 90 a for receiving the resin pellets 9 is provided at the upstream end of the cylinder 91 . A heater for melting the resin is provided on the outer peripheral surface of the cylinder 91 along the axial direction. Screw 92 extends rotatably within cylinder 91 . The motor 93 is connected to one axial end (upstream side) of the screw 92 . By driving the motor 93 , the screw 92 rotates within the cylinder 91 . Then, the resin pellets 9 introduced from the material inlet 90a are gradually melted by the heater and move toward the other (downstream) end of the screw 92 in the axial direction. A discharge part for injecting melted resin is provided at the downstream end of the cylinder 91, and the melted resin is injected into the mold one shot at a time from the discharge part.

In the granular material supply apparatus 100 configured as described above, the resin pellets 9 are heated and dried in the storage tank 10 and then passed through the discharge pipe 41 of the discharge section 40 to the material inlet 90a of the molding machine 90. supplied to As a result, the resin pellets 9 supplied to the molding machine 90 are sequentially injected from the ejection section into the mold for optical products. After one optical product is molded by injection molding, it is removed from the mold and the next shot is injected into the mold from the discharge port. As the manufacture of the optical product progresses, the resin pellets that are insufficient in the cylinder 91 are supplied from the discharge pipe 41 into the cylinder 91 through the material inlet 90a.

Here, in the conventional powder material supply device, the powder material before being supplied to the subsequent molding machine is supplied from the storage tank into the discharge pipe and then introduced into the material inlet of the molding machine. Until then, the temperature could become unstable while stored in this discharge tube. If the powder remains in the discharge pipe for a long period of time, the temperature of the powder may become unstable, which may lead to molding defects. In addition, since the manufacturing speed of the molded product (that is, the consumption speed of the resin pellets by the molding machine) fluctuates due to various factors such as the temperature of the mold, the flow rate of the resin pellets from the storage tank to the discharge pipe is simply Such a problem could not be solved simply by making the supply speed slower than before.

In this regard, the granular material supply device 100 according to the present embodiment has a unique configuration for suppressing the temperature of the granular material from becoming unstable within the discharge pipe 41 . The configurations unique to these embodiments will be described in detail below.

<1-2. Configuration of discharge pipe>
2 and 3 are longitudinal sectional views showing the configuration of the discharge section 40. FIG. As shown in FIGS. 2 and 3, a portion of the discharge pipe 41 vertically above a slide shutter 433, which will be described later, has a double structure. Specifically, this double structure portion of the discharge pipe 41 is composed of an inner discharge pipe 411 and an outer discharge pipe 412 . The inner discharge pipe 411 extends downward from a discharge port 121 provided at the vertically lower end of the storage tank 10 . Therefore, the resin pellets 9 pass through the internal space of the inner discharge pipe 411 . The outer discharge pipe 412 extends vertically outside the inner discharge pipe 411 in the radial direction. The lower end of the outer discharge pipe 412 is connected to the material inlet 90 a of the molding machine 90 . As described above, the exhaust pipe 41 has a double structure, thereby suppressing heat radiation from the powder.

In addition, the discharge pipe 41 has a concave portion 41a. More specifically, the discharge pipe 41 has a concave portion 41a that is concave radially outward from the inner peripheral surface of the outer discharge pipe 412 and that the distance from the outer discharge pipe 412 increases upward. That is, the recessed portion 41 a extends obliquely upward in a cylindrical shape from the upper and lower intermediate portions of the outer discharge pipe 412 .

<1-3. Configuration of Supply Amount Adjusting Mechanism>
A supply amount adjusting mechanism 43 is mounted in the concave portion 41a. The supply amount adjusting mechanism 43 is a mechanism that adjusts the amount of powder or granular material supplied from the storage tank 10 to the material inlet 90a. The supply amount adjusting mechanism 43 of this embodiment is of a slide shutter type.

More specifically, the supply amount adjusting mechanism 43 has an air cylinder (driving device) 431 , a disc portion 432 and a slide shutter 433 . The air cylinder 431 is a driving device for sliding the slide shutter 433 . The air cylinder 431 is mounted on the bottom (back) of the recess 41a. A rod 431a of the air cylinder 431 can move back and forth along the central axis of the recess 41a. A disc portion 432 is fixed to the tip portion of the rod 431 a of the air cylinder 431 . The disc portion 432 extends substantially perpendicularly to the axial direction of the rod 431a of the air cylinder 431 and partially closes the recess 41a. The edge of the disc portion 432 and the inner peripheral surface of the recess 41a face each other with a gap through which the resin pellets 9 cannot pass.

A slide shutter 433 is fixed on the opposite side of the rod 431a across the disk portion 432 when viewed in the vertical cross-sectional view of FIG. The slide shutter 433 has a flat plate shape extending obliquely along the shape of the recess 41a. By driving the air cylinder 431, the slide shutter 433 can move between the "closed position" shown in FIG. 2 and the "open position" shown in FIG. . When the slide shutter 433 is in the "closed position", the guiding path of the resin pellets 9 inside the inner discharge pipe 411 is closed. On the other hand, when the slide shutter 433 is in the "open position", the guide path of the resin pellets 9 inside the inner discharge pipe 411 is opened. As shown in FIG. 3, the slide shutter 433 when in the "open position" is generally accommodated within the recess 41a.

<1-4. Configuration of Level Sensor>
A sensor unit 50 including a level sensor 57 as a detection unit is attached to the lower end of the discharge pipe 41 . The level sensor 57 of the sensor unit 50 is a detector that detects the position (height) of the upper surface of the area where the granular material accumulates in the discharge pipe 41 . The level sensor 57 of this embodiment is a photoelectric sensor.

More specifically, the sensor unit 50 has a flange 51 , an inner tubular portion 52 , an outer tubular portion 53 , a support member 54 , a light projecting portion 55 , a light receiving portion 56 and a flange 58 . A combination of the light projecting section 55 and the light receiving section 56 constitutes a level sensor (detection section) 57 . The flange 51 is an annular plate material, and is attached to the lower end of the outer discharge pipe 412 using a fastening member such as a screw. The inner tubular portion 52 is a transparent cylindrical portion. The inner tubular portion 52 extends downward from the inner edge portion of the flange 51 substantially perpendicular to the plate surface of the flange 51 . When attached to the lower end of the discharge pipe 41 via the flange 51 , the internal space of the inner tubular portion 52 is continuous with the internal space of the outer discharge pipe 412 . A lower end portion of the inner cylindrical portion 52 is connected to the material inlet 90a.

The outer tubular portion 53 is a transparent cylindrical portion. The outer tubular portion 53 extends downward from the plate surface of the flange 51 substantially perpendicular to the plate surface of the flange 51 . The outer tubular portion 53 is provided radially outward of the inner tubular portion 52 and coaxially with the inner tubular portion 52 . The sensor unit 50 has a double structure in the radial direction with an inner tubular portion 52 and an outer tubular portion 53 . The inner tubular portion 52 and the outer tubular portion 53 are connected to an annular flange 58 . The flange 58 extends radially outward from the lower end of the inner tubular portion 52 .

The support member 54 is a part for supporting the level sensor 57 with respect to the outer tubular portion 53 . There are two support members 54, each having an upper surface portion 54a, a lower surface portion 54b, and a side surface portion 54c. The upper surface portion 54a and the lower surface portion 54b are provided to face each other in the vertical direction. The side surface portion 54c has a plate shape extending in the vertical direction, and connects the outer edge of the upper surface portion 54a and the outer edge of the lower surface portion 54b. The support member 54 is attached radially outward of the outer cylindrical portion 53 via a flange 58 . Specifically, the support member 54 is attached to the lower end of the outer cylindrical portion 53 .

The two side surface portions 54c are positioned 180° rotationally symmetrical when viewed in the axial direction, and the light projecting portion 55 is attached to one side and the light receiving portion 56 is attached to the other side portion 54c. 2, the light projecting portion 55 and the light receiving portion 56 are provided facing each other with the central axes of the inner cylindrical portion 52 and the outer cylindrical portion 53 interposed therebetween. The light projecting unit 55 can project light at timing based on a signal from the control unit 60, which will be described later. However, in this embodiment, the light projecting unit 55 continuously projects light. The light receiving unit 56 sends a detection signal based on the received light to the control unit 60, which will be described later.

In the level sensor 57 having such a configuration, when the upper surface of the area where the resin pellets 9 are retained is lower than the installation height of the level sensor 57, the light from the light projecting section 55 is received by the light receiving section 56. . On the other hand, when the upper surface of the area where the resin pellets 9 are retained is higher than the installation height of the level sensor 57, the light from the light emitting unit 55 is blocked by the resin pellets 9, and the light receiving unit 56 receives the light. not. Thereby, the level sensor 57 can detect the position of the upper surface of the deposited layer of the resin pellets 9 .

<1-5. Configuration of control system>
The control unit 60 is means for controlling the operation of each unit of the granular material supply device 100 . FIG. 4 is a block diagram showing the configuration of the control system of the granular material supply device 100. As shown in FIG. As shown in FIG. 4, the control unit 60 is electrically connected to the light projecting unit 55 and the light receiving unit 56 and the air cylinder 431 described above. The control unit 60 may be configured by a computer having an arithmetic processing unit such as a CPU and a memory, or may be configured by an electronic circuit. Further, the control unit 60 may be a control unit unique to the granular material supply device 100, or alternatively, may be a control unit that controls the granular material supply device 100 and the molding machine 1 in an integrated manner. . The control unit 60 controls the operations of the above units based on preset programs and input signals from the outside. As a result, the process of adjusting the supply amount of the resin pellets 9 to the subsequent molding machine 90 in the granular material supply device 100 proceeds.

<1-6. Control processing>
Next, a process of adjusting the supply amount of the resin pellets 9 to the molding machine 90, which is executed by the controller 60, will be described with reference to FIG. FIG. 5 is a flow chart showing the flow of processing executed by the control unit 60 when the resin pellets 9 are introduced into the material inlet 90a of the molding machine 90. As shown in FIG. The flow shown in FIG. 5 is repeated while the granular material supply device 100 and the molding machine 90 are in operation.

First, the control unit 60 acquires the detection result of the level sensor 57 (step S1). Specifically, the controller 60 attempts to receive a signal sent from the light receiver 56 .

Subsequently, the control unit 60 determines whether or not the level (height) of the resin pellet 9 has reached the installation position of the level sensor 57 (step S2). Specifically, when the control unit 60 receives a signal indicating that the light receiving unit 56 has received the light from the light projecting unit 55 , the upper surface of the area where the resin pellets 9 are staying is the level sensor 57 . It is judged that it is lower than the installation position (step S2, no). In this case, it is considered that the amount of resin pellets 9 remaining in the inner cylindrical portion 52 is not excessive. In other words, in this case, it is presumed that the residence time for the resin pellets 9 to stay in the inner cylindrical portion 52 is within a predetermined time.

That is, in this embodiment, the level sensor 57 is installed at the upper limit position of the level of the resin pellets 9 at which the residence time of the resin pellets 9 in the discharge pipe 41 can be kept within a predetermined time. The “predetermined time” refers to the time during which the temperature change from the temperature maintained in the storage tank 10 falls within a certain range while the resin pellets 9 are staying in the discharge pipe 41 . For example, the temperature of the resin pellets 9 may be between the temperature maintained in the storage tank 10 and the temperature set value at the material inlet 90 a of the molding machine 90 . Further, if the temperature difference between the temperature maintained in the storage tank 10 and the outside air temperature of the discharge pipe 41 is ΔT, the temperature change of the resin pellets 9 in the discharge pipe 41 was maintained in the storage tank 10. The predetermined time may be a time during which the deviation from the temperature falls within a range not exceeding half of ΔT. In addition, the "predetermined time" can be appropriately set to a time within a range in which the temperature change of the resin pellets 9 does not adversely affect molding. Specifically, the "predetermined time" may be set to, for example, 1 hour, preferably 30 minutes, or even more preferably 10 minutes. Also, the time may be set longer than 1 hour as long as molding defects do not occur due to temperature instability.

If it is determined in step S2 that the upper surface of the area where the resin pellets 9 are retained is lower than the installation position of the level sensor 57 (step S2, no), then the controller 60 controls the air cylinder 431 is made to perform one operation (step S3). That is, the control unit 60 causes the air cylinder 431 to perform a predetermined operation only once. This "predetermined operation" may be reciprocating movement of the slide shutter 433 between the closed position and the open position at a predetermined speed for a predetermined number of times. Alternatively, the stroke width of the slide shutter 433 may be It may be a default one. Alternatively, the slide shutter 433 may be positioned in the middle (half-open state) between the closed position and the open position for a predetermined time.

The "predetermined operation" is calculated in advance so that the retention time of the resin pellets 9 in the inner cylindrical portion 52 does not suddenly exceed the predetermined time when the air cylinder 431 is caused to perform this operation only once. It can be appropriately determined by a preliminary test or the like. In other words, in the "predetermined operation", the retention amount of the resin pellets 9 in the discharge pipe 41 suddenly increases, the retention time of the resin pellets 9 in the discharge pipe 41 becomes excessive, and the discharge It is appropriately determined so that the operation of supplying a small amount of resin pellets 9 into the discharge pipe 41 is performed so as not to cause a situation in which the temperature of the granules drops significantly within the pipe 41 . The "predetermined operation" is obtained by calculation, taking into account circumstances such as the capacity of the molding machine 90 or how many shots of the resin pellets 9 are consumed at one timing. If it takes one minute for one shot and the residence time needs to be within 30 minutes, it is set to supply 30 shots or less of the granular material.

On the other hand, if it is determined in step S2 that the upper surface of the area where the resin pellets 9 are stagnating has reached the installation position of the level sensor 57 (step S2, yes), the resin pellets 9 are removed any further. It is considered that the residence time of the resin pellets 9 in the inner cylindrical portion 52 exceeds the predetermined time when the resin pellets 9 are supplied to the discharge pipe 41 . Therefore, in that case, the control unit 60 does not cause the air cylinder 431 to perform the above-described predetermined operation, and maintains the position of the slide shutter 433 at the closed position (step S4).

After the process of step S3 or step S4, the control unit 60 shifts to the process of step S1 and acquires the detection result of the level sensor 57 again.

By repeating such processing, when the current level of the resin pellets 9 is lower than the installation position of the level sensor 57, the operation of supplying the resin pellets 9 to the discharge pipe 41 little by little is repeated. As a result, the level of the resin pellets 9 is brought into a state of substantially matching the installation position of the level sensor 57 . As a result, the state in which the residence time of the resin pellets 9 in the discharge pipe 41 is within the predetermined time period is maintained. Therefore, the temperature of the resin pellets 9 in the discharge pipe 41 is suppressed from decreasing, and molding defects in the subsequent molding machine 90 are less likely to occur.

From another point of view, in the granular material supply device 100 of the present embodiment, the level of the resin pellets 9 is maintained in a state substantially matching the installation position of the level sensor 57, so that the resin pellets 9 are supplied to the molding machine 90. There is very little possibility that the amount of the resin pellets 9 will run short. That is, in this embodiment, the inside of the cylinder 91 is always maintained in a full state when the granular material supply device 100 and the molding machine 90 are in operation. Therefore, the ability of the molding machine 90 can be used without waste, and the molded product can be manufactured efficiently.

As described above, in the granular material supply device 100 of the present embodiment, the control unit 60 determines whether the resin pellets 9 stay in the discharge pipe 41 within a predetermined time based on the detection result of the level sensor 57. The supply amount adjusting mechanism 43 is controlled so that As a result, the residence time of the resin pellets 9 in the discharge pipe 41 is set within a predetermined time. Therefore, it is possible to prevent the temperature of the resin pellets 9 from dropping while passing through the discharge pipe 41 with a simple and inexpensive structure without providing a separate heat retaining means or heating means around the discharge pipe 41 .

Further, the granular material supply device 100 of the present embodiment includes a heater 33 which is a heat source (heating unit) for heating the resin pellets 9 . Thereby, the temperature of the resin pellets 9 can be kept constant at an appropriate temperature before being supplied to the subsequent molding machine 90 . As a result, the occurrence of molding defects can be suppressed.

Further, in the granular material supply device 100 of the present embodiment, the hot air inlet (heating unit) 34 for introducing hot air heats the resin pellets 9 in the storage tank 10 . Thereby, the resin pellets 9 can be heated and dried in the storage tank 10 before being supplied to the subsequent molding machine 90 . Therefore, it is possible to make it more difficult for molding defects to occur.

Further, in the granular material supply device 100 of the present embodiment, the level sensor 57 is attached to the lower end of the discharge pipe 41 . This makes it possible to accurately detect the timing at which the position of the upper surface of the area where the resin pellets 9 are deposited reaches the discharge pipe 41 . Therefore, the amount required for molding can be maintained while minimizing the amount of resin pellets 9 that dissipate heat.

Further, in the present embodiment, the controller 60 controls the supply amount adjusting mechanism 43 so that the residence time of the resin pellets 9 in the discharge pipe 41 is preferably within one hour. As a result, when the polycarbonate, which is the resin pellet 9 according to the present embodiment, is heated and dried at 120°C in the storage tank 10, the temperature of the resin pellet 9 in the discharge pipe 41 is increased to 70°C or higher. , more preferably at 100° C. or higher.

Further, in this embodiment, a part of the discharge pipe 41 in the axial direction has a double structure including an inner discharge pipe 411 and an outer discharge pipe 412 . Moreover, the sensor unit 50 has a double structure including an inner tubular portion 52 and an outer tubular portion 53 . The resin pellets 9 pass through the internal space of the inner discharge pipe 411 and the inner tubular portion 52 . As a result, it is possible to prevent the heat of the resin pellets 9 from being taken away by the external gas (air) in the process of passing through the discharge pipe 41 and the sensor unit 50 .

Further, the supply amount adjusting mechanism 43 according to this embodiment is of a slide shutter type having a slide shutter 433 and an air cylinder (driving device) 431 . As a result, the amount of resin pellets 9 supplied from the storage tank 10 to the material inlet 90a of the molding machine 90 can be adjusted with a simple and inexpensive configuration.

Further, the discharge pipe 41 according to the present embodiment has the recess 41a described above. The slide shutter 433 at the open position is accommodated in the recess 41a. As a result, it is possible to form the concave portion 41a, which is the area for retracting the slide shutter 433, with an inexpensive structure. Further, since the concave portion 41a has a tubular shape extending obliquely upward, the resin pellets 9 are less likely to accumulate in the concave portion 41a. Therefore, the resin pellets 9 can be smoothly supplied to the molding machine 90 .

Moreover, in this embodiment, the storage tank 10, the discharge pipe 41, and the material inlet 90a are arranged in a straight line in the vertical direction. As a result, compared to a configuration in which, for example, a screw conveyor extending in the horizontal direction is interposed in the middle of the conveying path of the resin pellets 9, the members with which the resin pellets 9 come into contact are minimized, and the heat dissipation of the resin pellets 9 is suppressed. can do.

<2. Second Embodiment>
Next, a granular material supply device 200 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 schematically shows the configuration of a granular material supply device 200 according to the second embodiment.

The granular material supply device 200 according to the second embodiment mainly differs from the granular material supply device 100 according to the first embodiment in that it has a second circulation pipe 70 . In the following, members having the same configurations and functions as those shown in the explanation of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the explanation thereof is omitted.

The second circulation pipe 70 is a pipe for sending the gas inside the discharge pipe 41 to the circulation pipe 30 . One end of the second circulation pipe 70 is connected to a second exhaust port 413 provided on the side wall of the outer discharge pipe 412 . The second exhaust port 413 is located between the sensor unit 50 and the material input port 90 a of the molding machine 90 . The other end of the second circulation pipe 70 is connected to the connection port 35 provided in the circulation pipe 30 .

An ejector 71 is provided in the middle of the route of the second circulation pipe 70 . The ejector 71 has a main pipe 711 and a gas blowout portion 712 . The main pipe 711 is a cylindrical pipe forming part of the second circulation pipe 70 . The gas blowout part 712 is located inside the main pipe 711 . Also, the gas blowing section 712 is connected to the gas supply section 72 .

The gas supply unit 72 is a mechanism for supplying nitrogen gas, which is an inert gas, to the gas blowout unit 712 of the ejector 71 . The gas supply section 72 has a nitrogen gas generator 721 and an air supply pipe 722 . The upstream end of the air supply pipe 722 is connected to the nitrogen gas generator 721 . A downstream end of the air supply pipe 722 is connected to the gas blowout portion 712 . A valve 723 is provided in the middle of the air supply pipe 722 .

The nitrogen gas generator 721 generates dry nitrogen gas having a pressure higher than the outside pressure (atmospheric pressure) and the pressure inside the second circulation pipe 70 . Therefore, when the valve 723 is opened, nitrogen gas having a pressure higher than the atmospheric pressure (positive pressure) is supplied from the nitrogen gas generator 721 to the gas blowout portion 712 through the air supply pipe 722 . Then, inside the main pipe 711 , nitrogen gas is blown out from the gas blowing part 712 toward the downstream side. Due to this flow of nitrogen gas, negative pressure is partially generated in the space on the upstream side of the gas blowing section 712 in the second circulation pipe 70 . Due to the negative pressure and the viscosity of the gas, the ejector 71 generates an airflow in the second circulation pipe 70 from the second exhaust port 413 toward the connection port 35 as indicated by A4 in FIG.

The valve 723 described above is opened before operating the granular material supply device 200 and the molding machine 90 . As a result, the air in the storage tank 10, the supply section 20, the circulation pipe 30, and the second circulation pipe 70 is replaced with nitrogen gas. In this state, the granular material supply device 200 and the molding machine 90 are operated.

In the granular material supply apparatus 200 configured as described above, part of the high-temperature nitrogen gas in the storage tank 10 flows through the discharge pipe 41 into the second circulation pipe 70 and joins the circulation pipe 30. is reheated. The reheated nitrogen gas is supplied into the reservoir 10 and part of it flows again to the discharge pipe 41 . Therefore, the temperature drop of the resin pellets 9 in the discharge pipe 41 can be further suppressed. The position of the second exhaust port 413 does not necessarily have to be between the sensor unit 50 and the material inlet 90a of the molding machine 90, and may be above the sensor unit 50, for example.

Thus, in the granular material supply device 200 of the present embodiment, the internal space of the storage tank 10 and the internal space of the discharge pipe 41 are supplied with nitrogen gas as an inert gas. As a result, it is possible to reduce the possibility that the resin pellets 9 are deteriorated due to oxidation or the like. Therefore, it is possible to make it more difficult for molding defects to occur.

Further, in the granular material supply device 200 of the present embodiment, the internal space of the storage tank 10 and the internal space of the discharge pipe 41 are maintained at a pressure higher than the atmospheric pressure. This prevents outside air from entering the storage tank 10 or the discharge pipe 41 before being supplied to the subsequent molding machine 90, and reduces the risk of the resin pellets 9 absorbing moisture from the outside air. can do. Therefore, it is possible to make it more difficult for molding defects to occur.

<3. Variation>
Although exemplary embodiments of the invention have been described above, the invention is not limited to the above embodiments.

In the above embodiment, the supply amount adjustment mechanism 43 is of the slide shutter type, but the supply amount adjustment mechanism is not limited to this type. Alternatively, the supply amount adjusting mechanism may be configured using a known valve such as a rotary valve, a ball valve, a butterfly valve, or a valve structure such as a cut gate, a flap damper, a choke valve, or the like.

Although the level sensor 57 is a photoelectric sensor in the above embodiment, it is not necessarily limited to this. Alternatively, the level sensor may be a capacitive sensor, for example. Alternatively, the level of the granular material may be detected by applying ultrasonic waves to the upper surface of the deposited layer of resin pellets from above the storage tank. Alternatively, it may be a mechanical sensor that detects the level of granular material by physically contacting the granular material and rotating. Alternatively, a temperature sensor or the like may be used as the level sensor. In addition, level detection is performed by the molding machine 90 or other equipment, and a method of receiving signals from these external equipment to control the level of the resin pellets 9 may be employed.

In the above embodiment, the controller 60 controls the supply amount adjusting mechanism 43 so that the resin pellets 9 stay in the discharge pipe 41 for a predetermined time or less. However, in addition to this, the control section 60 may perform control so as to satisfy the condition that the temperature of the resin pellets 9 in the discharge pipe 41 is equal to or higher than a predetermined temperature. The predetermined temperature is at least higher than the ambient temperature, and the preferred range differs depending on the type of resin and molding conditions. Specifically, when the resin pellets 9 are made of polycarbonate as in the above embodiment and the heat drying temperature in the storage tank 10 is 120°C, the temperature of the resin pellets 9 in the discharge pipe 41 is 70°C. The control unit 60 may perform control so that the temperature is more preferably 100° C. or higher.

In the above embodiment, the resin pellets 9 are made of polycarbonate, but are not limited to this, for example, polybutylene terephthalate, polyethylene terephthalate, methacrylic resin, polyamide, polyphenylene sulfide, polyimide, Various general-purpose plastics such as polyacetal, engineering plastics, and super engineering plastics may be used. Further, the powder or granular material is not limited to resin pellets, and may be powder or granules used for resin powder, food powder, pharmaceuticals, chemical industrial materials, building materials, industrial materials, and the like. That is, various known powders can be used as the material of the present invention.

In parallel with the process of adjusting the supply amount of the resin pellets 9 to the molding machine 90, the controller 60 may also perform the error determination process shown in FIG. Briefly describing the error determination process, first, the control unit 60 determines whether or not the slide shutter 433 has been operated (step S11). If the slide shutter 433 has not been operated as a result of the determination in step S11 (step S11, no), the control unit 60 waits until the slide shutter 433 is operated next time. On the other hand, if the slide shutter 433 has been operated as a result of the determination in step S11 (step S11, yes), the control unit 60 acquires the detection result of the level sensor 57, and the operation of the slide shutter 433 within a certain time period. Then, it is determined whether or not the upper surface position of the resin pellet 9 has reached above the sensor installation height (step S12). As a result of the determination in step S12, if the upper surface position of the resin pellet 9 has reached above the sensor installation height within a certain period of time after the operation of the slide shutter 433 (step S12, yes), the resin pellet 9 in the storage tank 10 It is considered that the bridge of In other words, it can be considered that the resin pellets 9 are smoothly supplied from the storage tank 10 to the discharge pipe 41 . In that case, the control unit 60 terminates the error determination process. On the other hand, as a result of the determination in step S12, if the upper surface position of the resin pellet 9 has not reached above the sensor installation height within a certain period of time after the operation of the slide shutter 433 (step S12, no), in the storage tank 10 There is a high possibility that bridges of the resin pellets 9 have occurred. In that case, the controller 60 outputs an error indicating that the resin pellet 9 is not discharged properly (step S13). By performing such control processing, when the supply of the resin pellets 9 from the storage tank 10 to the discharge pipe 41 is delayed due to occurrence of bridging or the like, the user can know this by outputting an error. As a result, some measures can be taken.

In the above embodiment, when the level of the material is less than the installation position of the level sensor 57, one operation (predetermined operation) is uniformly performed. However, depending on whether the resin pellets 9 are introduced into the material inlet 90a through the discharge pipe 41 or the purge material is introduced into the material inlet 90a through the discharge pipe 41, the "predetermined operation" mode is changed. can be different. Specifically, when charging the purge material, a larger amount than when charging the resin pellets 9 may be supplied to the material charging port 90a in a "predetermined operation".

In the above embodiment, the storage tank 10, the discharge pipe 41, and the material inlet 90a are arranged in a straight line in the vertical direction. However, instead of this, for example, a path inclined with respect to the vertical direction may be interposed in the middle of the transport path of the resin pellets 9 . Specifically, the middle portion of the discharge pipe 41 may be partially inclined with respect to the vertical direction.

Also, the detailed configuration and layout of each part may be different from those shown in the drawings of the present application. Also, the elements appearing in the above embodiments and modifications may be appropriately combined as long as there is no contradiction.

9 resin pellets (granules)
10 storage tank 41 discharge pipe 43 supply amount adjustment mechanism 57 level sensor (detection unit)
60 control unit 90 molding machine 90a material input port 100 powder supply device

Claims (12)

A granular material supply device for supplying granular material to a subsequent molding machine,
a storage tank in which the powder or granular material is stored while being maintained at a constant temperature or higher;
a discharge pipe that connects the lower end of the storage tank and the material inlet of the molding machine and guides the powder from the storage tank to the material inlet according to its own weight;
a detection unit that detects the position of the upper surface of the area where the granular material accumulates in the discharge pipe;
a supply amount adjustment mechanism attached to the discharge pipe and adjusting the amount of the granular material supplied from the storage tank to the material input port;
a control unit that controls the supply amount adjustment mechanism so that the retention time of the particulate material in the discharge pipe is within a predetermined time based on the detection result of the detection unit;
with
The powdery material supply device, wherein the detection unit is attached to the lower side of the discharge pipe. The granular material supply device according to claim 1,
A heat retaining structure is provided on the lower side of the discharge pipe to suppress heat dissipation of the granular material passing through the discharge pipe,
Granule feeder. The powdery or granular material supply device according to claim 2,
The heat insulation structure is
an inner barrel;
an outer cylindrical portion disposed radially outward of the inner cylindrical portion;
is a multiple structure containing
Granule feeder. The powdery or granular material supply device according to any one of claims 1 to 3,
A granular material supply device further comprising a heating unit that heats the granular material. The powdery or granular material supply device according to claim 4,
The powdery material supply device, wherein the heating unit heats the powdery material inside the storage tank. The powdery or granular material supply device according to any one of claims 1 to 5,
A granular material supply device, wherein an inert gas is supplied to the internal space of the storage tank and the internal space of the discharge pipe. The powdery or granular material supply device according to any one of claims 1 to 6,
The granular material supply device, wherein the internal space of the storage tank and the internal space of the discharge pipe are maintained at a pressure higher than atmospheric pressure. The powdery or granular material supply device according to any one of claims 1 to 7,
The control unit controls the supply amount adjusting mechanism so that the residence time is within one hour. The powdery or granular material supply device according to any one of claims 1 to 8,
At least part of the discharge pipe in the vertical direction,
an inner discharge tube;
an outer discharge pipe disposed radially outward of the inner discharge pipe;
is a multiple structure containing
The granular material supply device, wherein the granular material passes through the inner space of the inner discharge pipe. The granular material supply device according to any one of claims 1 to 9,
The supply amount adjustment mechanism is
a slide shutter that is movable between a closed position that closes a guide path for the granular material in the discharge pipe and an open position that opens the guide path;
a driving device that slides the slide shutter;
A granular material supply device. The powdery or granular material supply device according to claim 10,
The discharge pipe has a recess that is recessed radially outward from the inner peripheral surface thereof, and that the distance from the side wall forming the inner peripheral surface increases as it goes vertically upward,
A granular material supply device, wherein the slide shutter at the open position is accommodated in the recess. The powdery or granular material supply device according to any one of claims 1 to 11,
The control unit detects that the position of the upper surface of the granular material has not reached a predetermined position within a certain period of time after the supply amount adjusting mechanism supplies the granular material based on the detection result of the detection unit. A granular material supply device that determines that powder supply is defective and outputs an error when it is determined.

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