Material transportation device and material transportation method

Abstract

To provide a material transportation device and a material transportation method that can effectively prevent the occurrence of blockage of granular material in a material transportation pipe or shortage of granular material at a transportation destination.SOLUTION: A material transportation device 1 pneumatically transports granular material from a quantitative supply part 24 provided at a transportation source 20 for quantitatively supplying granular material to a transportation destination 3a connected to a suction air source 15 via a material transportation pipe 6, and includes: a pressure sensor 17 for detecting pressure in a path 7 connected to a suction side of the suction air source including the material transportation pipe; a control unit 11 for changing and controlling the supply amount of the quantitative supply part based on the detection value of the pressure sensor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to material transport devices and methods. [Background technology]

[0002] Conventionally, there has been known a material transport device that pneumatically transports powdered or granular material from a transport source such as a storage unit to a transport destination through a material transport pipe. In such a material transport device, problems can occur if the powdered or granular material is blocked in the material transport pipe or if there is a shortage of the powdered or granular material at the transport destination. For example, the following Patent Document 1 discloses a material transport device that connects a discharge port of a rotary valve provided below a material tank to a collector installed in a molding machine with a pipe, and pneumatically transports the material supplied from the rotary valve to the collector through the pipe by the suction force of a suction air source. This material transport device is equipped with a control unit that controls the air volume or speed of the suction air source based on the torque detected by a physical quantity detection unit that detects physical quantities such as torque related to the output of an inverter that drives a motor of the suction air source. This material transport device is also configured to control the inverter of the rotary valve that supplies the material and reduce the amount of material supplied when a determination unit determines that the torque is equal to or greater than a predetermined threshold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 155655 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the material transport device described in Patent Document 1, if the air volume or speed in the pipe is changed to be within an appropriate range based on the torque of the motor of the suction air source, the torque will also fluctuate, making it difficult to optimize the threshold setting for controlling the amount of material supplied, and there is a concern that control will become more complicated.

[0005] The present disclosure has been made in consideration of the above-mentioned situation, and aims to provide a material transport device and a material transport method that can effectively suppress the occurrence of blockages of powdered or granular material in material transport pipes and shortages of powdered or granular material at the destination. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, configuration 1 of the material transport device disclosed herein is a material transport device that pneumatically transports powdered or granular material from a quantitative supply unit that is provided at a transport source and supplies powdered or granular material in a quantitative manner, via a material transport pipe, to a destination connected to a suction air source, and is characterized in that it is equipped with a pressure sensor that detects the pressure of a path connected to the suction side of the suction air source, including the material transport pipe, and a control unit that changes and controls the supply amount of the quantitative supply unit based on the detection value of the pressure sensor.

[0007] The following description of the embodiments will disclose that the material transport device according to the present disclosure may include the following subsidiary configurations. <Configuration 2> In configuration 1, the control unit may reduce the supply amount of the constant-volume supply unit when the detection value of the pressure sensor falls below a low-pressure threshold value that is lower than a predetermined reference pressure value, and may increase the supply amount of the constant-volume supply unit when the detection value of the pressure sensor exceeds a high-pressure threshold value that is higher than the reference pressure value. <Configuration 3> In configuration 2, the control unit may reduce the supply amount of the constant-volume supply unit when the detection value of the pressure sensor falls below the low-pressure side threshold and a preset low-pressure side delay time has elapsed, and may increase the supply amount of the constant-volume supply unit when the detection value of the pressure sensor exceeds the high-pressure side threshold and a preset high-pressure side delay time has elapsed. <Configuration 4> In configuration 3, the low-voltage side delay time may be shorter than the high-voltage side delay time. <Component 5> In any one of configurations 1 to 4, the pressure sensor may be installed so as to detect the pressure in a path in the vicinity of the suction air source. <Component 6> In any one of configurations 1 to 5, the pressure sensor may be installed to detect the pressure of an air suction pipe downstream of a dust collection section disposed in the air suction pipe connecting the destination and the suction air source. <Component 7> In configuration 6, a differential pressure gauge may be provided that measures a pressure difference between the upstream path and the downstream path of the dust collecting unit. <Component 8> In any one of configurations 1 to 7, a transport pipe for transporting powdered or granular material from a plurality of pulverizers may be connected to the storage portion constituting the transport source.

[0008] In order to achieve the above-mentioned object, the material transport method disclosed herein is a material transport method in which powdered or granular material is pneumatically transported from a quantitative supply unit provided at a source of transport and supplying a quantitative amount of powdered or granular material via a material transport pipe to a destination connected to a suction air source, and is characterized in that the supply amount of the quantitative supply unit is changed based on the detection value of a pressure sensor that detects the pressure of a path connected to the suction side of the suction air source, including the material transport pipe. Effect of the Invention

[0009] By being configured as described above, the material transport device and material transport method disclosed herein can effectively prevent the occurrence of blockages of powdered or granular material in the material transport pipe and shortages of powdered or granular material at the destination. [Brief description of the drawings]

[0010] [Figure 1] 1 is a partially cutaway schematic system diagram illustrating an example of a material transport system incorporating an example material transport apparatus according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic block diagram of the material transport device. [Diagram 3]4 is a schematic time chart showing an example of a basic operation executed in the material transport device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In FIG. 1, pipelines (pipes) and the like that serve as paths through which transport air and powdered and granular materials pass are shown diagrammatically by solid lines. 3, the horizontal axis is the time axis, and the vertical axis is the pressure sensor detection value (gauge pressure), and the transition is shown diagrammatically. The side approaching atmospheric pressure is the high pressure side, and the side increasing negatively from atmospheric pressure (the side with a larger absolute value, the high vacuum side) is the low pressure side.

[0012] 1 to 3 are schematic diagrams showing an example of a material transport device according to the present embodiment, an example of a material transport system incorporating the same, and an example of basic operations including a material transport method according to the present embodiment that is performed using the same. As shown in Fig. 1, the material transport device 1 according to this embodiment pneumatically transports powdered or granular material from a constant quantity supply unit 24, which is provided at a transport source 20 and supplies a constant quantity of powdered or granular material, to a transport destination (3a) which communicates with a suction blower 15 constituting a suction air source via a material transport pipe 6. This material transport device 1 is equipped with a pressure sensor 17 which detects the pressure in a path (6, 7) which communicates with the suction side of the suction blower 15, including the material transport pipe 6, and a control unit 11 (see Fig. 2) which changes and controls the supply amount of the constant quantity supply unit 24 based on the detection value of this pressure sensor 17.

[0013] With the above-mentioned configuration, if the pressure in the path (6, 7) communicating with the suction side of the suction blower 15 becomes low (lower toward high vacuum), the supply amount of the constant quantity supply unit 24 of the transport source 20 can be controlled to decrease, and the occurrence of blockage of the powdered or granular material in the material transport pipe 6 can be suppressed. In other words, if the pressure in the path (6, 7) communicating with the suction side of the suction blower 15 becomes low, it is determined that the mixing ratio of the powdered or granular material in the material transport pipe 6 is excessive, and the supply amount of the constant quantity supply unit 24 of the transport source 20 is controlled to decrease. On the other hand, if the pressure in the path (6, 7) communicating with the suction side of the suction blower 15 becomes high (higher toward atmospheric pressure), the supply amount of the constant quantity supply unit 24 of the transport source 20 can be controlled to increase, and the occurrence of a shortage of the powdered or granular material in the transport destination (3a) can be suppressed. In other words, if the pressure in the path (6, 7) connected to the suction side of the suction blower 15 becomes high, it is determined that the mixing ratio of the powdered or granular material in the material transport pipe 6 is too low, and the supply amount of the fixed quantity supply section 24 of the transport source 20 is controlled to be increased.

[0014] As a result, for example, even when powdered or granular materials with different bulk densities are irregularly added to the transport source 20 to form powdered or granular material layers with different bulk densities, that is, when it is difficult to preset the supply amount of the constant quantity supply unit 24 according to the bulk density of the powdered or granular material, the supply amount of the constant quantity supply unit 24 can be adjusted to an appropriate amount by monitoring the pressure of the path (6, 7) communicating with the suction side of the suction blower 15. As a result, the material transport device 1 is suitable for a case where, for example, a plurality of transport pipes 9 for transporting powdered or granular materials with different bulk densities are connected to the storage unit 21, which is the transport source 20. In addition, since the mixing ratio of the powdered or granular materials in the material transport pipe 6 can be optimized without changing the rotation speed of the blower drive unit 16 (see FIG. 2), such as the motor of the suction blower 15, the suction blower 15 can be used at its maximum capacity. Furthermore, compared to a configuration in which the torque of the motor of the suction air source, which varies depending on the air volume or speed, is monitored, the reference pressure value can be easily set, and the condition inside the material transport pipe 6 can be accurately detected by monitoring the pressure fluctuations in the path (6, 7) communicating with the suction side of the suction blower 15. Furthermore, by monitoring the pressure, the occurrence of a leak in the path (6, 7) communicating with the suction side of the suction blower 15 can also be detected.

[0015] The powdered or granular material transported by the material transport device 1 refers to a powder or granular material, but includes fine flake-shaped (flake-shaped), short fiber-shaped, sliver-shaped, and fluff-shaped materials. The above-mentioned materials may be any materials, such as synthetic resin materials such as resin pellets and resin fiber pieces, metal materials, semiconductor materials, wood materials, pharmaceutical materials, and food materials. The powdered or granular material may be, for example, synthetic resin molded products including synthetic resin sheets, synthetic resin films, and synthetic resin containers (bottles), or crushed materials obtained by crushing or crushing rubber molded products using a crusher or a crusher. In addition, the powdered or granular material may be, for example, natural materials (virgin materials), the above-mentioned crushed materials, master batch materials, and various additives, when synthetic resin sheets, synthetic resin films, and other synthetic resin molded products are molded at the destination (3a) of the material transport device 1. The powdered or granular material may include reinforcing fibers such as glass fibers and carbon fibers.

[0016] In this embodiment, the transport pipe 9 for transporting powdered material from the multiple pulverizers 8 is connected to the storage section 21 constituting the transport source 20. With this configuration, the powdered material, which is pulverized in the multiple pulverizers 8 and stored in layers in the storage section 21 and often has a large difference in bulk density, can be smoothly transported by air toward the transport destination (3a). For example, when the material to be pulverized generated in a molding factory that molds synthetic resin sheets and synthetic resin films is pulverized in each pulverizer 8, the bulk density of the pulverized material pulverized in each pulverizer 8 may be significantly different (for example, the bulk density may differ by about 1.5 to 3 times) depending on the thickness of the pulverized material, additives, etc. In addition, for example, when the pulverized material pulverized in different types of pulverizers is introduced into the storage section 21, or when the pulverized material that has been pulverized in advance by purchasing or the like is brought in from the outside and introduced into the storage section 21, the bulk density may be significantly different or unknown. In this way, even if the bulk density of the powdered or granular material being transported changes significantly during transportation, the supply amount from the constant quantity supply unit 24 can be controlled to increase or decrease, thereby enabling smooth pneumatic transport to the destination (3a).

[0017] The destination (3a) of this material transport device 1 may be a collector 3a that separates and collects the powdered or granular material pneumatically transported through the material transport pipe 6 from the transport air. Such a collector 3a may be provided with an inlet to which the downstream end of the material transport pipe 6 is connected and a suction port to which an air suction pipe 7 communicating with a suction blower 15 is connected, and a separation section that separates the powdered or granular material from the transport air flowing toward the suction port. Such a separation section may be a punched metal or net-like (mesh-like) filter that allows dust to pass in addition to the transport air, but prevents the passage of the raw powdered or granular material.

[0018] This collector 3a may be provided in a supply tank 3 (3A) installed on the molding machine 2 as the supply destination. In this case, the supply tank 3 (3A) may be understood as the transport destination of the material transport device 1. In the illustrated example, a plurality of (two in the illustrated example) supply tanks 3, 3 are provided on the molding machine 2. The supply tanks 3, 3 may be provided with an appropriate material sensor that outputs a material request signal. Also, the supply tanks 3, 3 may be provided with an appropriate material sensor that outputs a material full signal. These supply tanks 3, 3 include a first supply tank 3A for storing powdered or granular material (e.g., crushed material) transported from a storage section 21 described below, and a second supply tank 3B for storing powdered or granular material (e.g., natural material) transported from a transport source 4 different from the storage section 21. A suitable suction air source 5 and the like that is driven when pneumatically transporting the powdered or granular material from the transport source 4 through a material transport pipe is connected to the collector 3a of the second supply tank 3B via an air suction pipe.

[0019] The molding machine 2 may be an extrusion molding machine for molding synthetic resin sheets or synthetic resin films, an injection molding machine for molding various synthetic resin molded products, or other molding machines such as a compression molding machine. The destination of the collector 3a (supply tank 3) to which the material is transported by the material transport device 1 is not limited to a single destination, but may be multiple destinations. The destination of the material transport device 1 is not limited to the collector 3a of the supply tank 3 installed on the molding machine 2, but may be a collector installed in a drying device or the like, or may be various other destinations. The material transport device 1 may form a material transport system by one or both of the collector 3a to which the material is transported and the transport source 20.

[0020] In the illustrated example, four crushers 8 are connected to the storage section 21 constituting the transport source 20 via transport pipes 9. Such crushers 8 may be crushers that crush materials to be crushed, such as molding by-products or defective moldings of molded products produced in various molding machines, or recycled materials. Such a crusher 8 may be configured, for example, to crush the input material to be crushed using a fixed blade provided in a housing and a rotating blade provided so as to be freely rotatable within the housing, or may have various other configurations. The transport pipe 9 is connected so that the upstream end communicates with a storage section provided at the lower end of the crusher 8. The transport pipe 9 is provided with a transport source that transports the pulverized material toward the storage section 21. Such a transport source may be a plate fan or the like that transports the pulverized material toward the downstream side by passing it through a fan together with air.

[0021] In the illustrated example, the transport pipes 9 connected to each of the multiple pulverizers 8 are individually connected to the storage section 21, but the present invention is not limited to this embodiment. For example, the storage section 21 may be provided with a collector pipe to which the multiple transport pipes 9 are connected. Alternatively, the storage section 21 may be provided with a pipeline in which the multiple transport pipes 9 are joined during transport. In addition, in the illustrated example, the pulverizers 8 are each provided with a transport source, but all or a plurality of the pulverizers 8 may be provided with a common transport source. In addition, a collector to which the transport pipes 9 are connected may be provided at the upper end of the storage section 21. The embodiment of transporting the pulverized material from the pulverizers 8 to the storage section 21 is not limited to the above-mentioned example, and may be transported by dropping the pulverized material under its own weight, or may be configured in various other ways. In addition, the transport source for transporting (supplying) the powdered material to the storage section 21 may be various other transport sources instead of or in addition to the pulverizers 8.

[0022] The storage section 21 constitutes a container for storing powdered or granular material and may be a tank, a silo, a hopper, or the like. The upper end portion of the storage section 21 may be cylindrical, such as a square tube or a cylinder, and the lower end portion may be inverted pyramid shape, such as an inverted square pyramid or an inverted cone, tapering toward the lower end. The storage section 21 is provided with an appropriate material sensor for detecting the storage level of the powdered or granular material. Such a material sensor may be a sensor capable of detecting the lower limit and upper limit of the storage level of the powdered or granular material in the storage section 21, and the illustrated example shows an example in which a plurality of material sensors are provided. An exhaust pipe that exhausts the transport air that transports the pulverized material from the pulverizer 8 to the storage section 21 is connected to the storage section 21. A dust collector 29 such as a bag filter that captures dust and the like contained in the transport air is connected to the end (downstream end) of this exhaust pipe.

[0023] The storage section 21 is provided with a bridge suppression mechanism 23 that suppresses the occurrence of bridges in the storage section 21. The crushed material obtained by crushing the synthetic resin sheet or synthetic resin film as described above tends to become fluffy and easily bridge, but if the bridge suppression mechanism 23 is provided, the bridging of the crushed material in the storage section 21 can be effectively suppressed. In the illustrated example, the bridge suppression mechanism 23 is provided with a screw that is rotated by a drive unit such as a motor. Such a screw may be configured such that one axial side portion and the other axial side portion are formed in a reverse spiral shape so as to transport the powdered material from both axial ends to the axial center. The bridge suppression mechanism 23 is not limited to a configuration that includes such a screw, but may also be configured with a rotating blade (agitator). In addition, the bridge suppression mechanism 23 is not limited to a configuration that includes a mechanism that mechanically stirs the powdered material in the storage section 21, but may also be configured with a mechanism that applies impact or vibration to the side wall portion of the storage section 21, may also be configured with a mechanism that ejects compressed air in the storage section 21, or may have various other configurations. It should be noted that such a bridge suppression mechanism 23 may not be provided.

[0024] The constant-quantity supply unit 24 is provided at the lower end of the storage unit 21. In this example, the constant-quantity supply unit 24 is a screw feeder equipped with a screw 25. With this configuration, even when the powdered or granular material to be supplied is a fluffy pulverized material as described above, it can be forcibly pushed out and supplied quantitatively toward the downstream side. The constant-quantity supply unit 24 includes a supply-side drive unit 26 (see FIG. 2), such as a motor that rotates the screw 25, and a cylindrical portion (trough) that houses the screw 25. One axial end of the cylindrical portion is provided with an inlet that communicates with a box-shaped receiver 27 that receives the pulverized material. In the illustrated example, the other axial end of the cylindrical portion is provided with an outlet that discharges the powdered material in the storage portion 21, but the present invention is not limited to this. The upstream end of the material transport pipe 6 is connected to the receiving section 27. The receiving section 27 is provided with a material sensor 28 that detects an upper limit level of the material in the receiving section 27. The control section 11 described below or another control section may execute control to stop the constant quantity supply section 24 (supply side drive section 26) when the material sensor 28 detects the upper limit level in the receiving section 27. With this configuration, clogging of the powdered or granular material in the receiving section 27 or the material transport pipe 6 downstream of the receiving section 27 can be suppressed. The receiving section 27 is also provided with an air introduction section that introduces air (outside air) via an appropriate filter or the like when the powdered or granular material is pneumatically transported.

[0025] The constant-volume supply unit 24 can change the supply amount by changing and controlling the number of revolutions (rotation speed) of the screw 25 (supply-side drive unit 26). As shown in FIG. 2, the supply-side drive unit 26 of the constant-volume supply unit 24 is provided with an inverter 26a that changes the number of revolutions of the supply-side drive unit 26. That is, in this embodiment, the inverter 26a functions as a supply amount change unit that changes the supply amount of the constant-volume supply unit 24. For example, such an inverter 26a may be a VVVF (variable voltage / variable frequency) type that converts AC input from a commercial drive power source into DC in a converter circuit, and converts it into AC with a predetermined output frequency and a predetermined output voltage in an inverter circuit. That is, by changing (converting) and controlling the output frequency of the inverter 26a, the number of revolutions of the supply-side drive unit 26 (screw 25) is changed, and the supply amount of the constant-volume supply unit 24 is changed.

[0026] The frequency output by the inverter 26a to the supply side drive unit 26 may be configured to be continuously variable within a range of, for example, 20 Hz to 120 Hz or 30 Hz to 90 Hz, or may be preset in multiple steps. For example, in the above-mentioned constant-volume supply unit 24, the frequency of the inverter 26a may be preset in multiple steps so that the supply amount can be adjusted in advance depending on the bulk density of the powdered or granular material to be supplied, the desired supply amount, etc. In such a case, the material transport device 1 of the present disclosure can be realized without adding a new inverter 26a, etc. to the constant-volume supply unit 24. 3 shows an example in which the frequency of the inverter 26a is set in advance to seven stages (seven-speed change). In this example, the frequencies are set from the lowest first frequency F1 to the highest seventh frequency F7. If the frequency of the inverter 26a is set to the lowest first frequency F1, the screw 25 rotates at the slowest speed and the supply amount is the smallest. On the other hand, if the frequency of the inverter 26a is set to the highest seventh frequency F7, the screw 25 rotates at the highest speed and the supply amount is the largest.

[0027] The number of stages of the frequency of the inverter 26a that is changed and controlled as described above is not limited to seven stages. Furthermore, the constant-volume feeder 24 is not limited to a screw feeder equipped with the screw 25, but may be any other constant-volume feeder such as a rotary valve, a mass feeder, a table feeder, or a vibration feeder. Also, a plurality of transport sources 20 as described above may be provided. In this case, the material transport pipes 6 of the plurality of transport sources 20 may be joined at an intermediate location, and the joined material transport pipes 6 may be connected to the collector 3a as the transport destination. The transport source 20 is not limited to the storage section 21 for storing the pulverized material as described above, but may also be a storage section for storing various powdered and granular materials, or may be a storage section for a weighing device, a blending device, a drying device, or the like. The transport source 20 and the transport destination (3a) of the material transport device 1 in this embodiment are not limited to the configurations described above, and various other modifications are possible.

[0028] The pressure sensor 17 may be installed to detect the pressure in the path (7) near the suction blower 15. With this configuration, the pressure can be detected more stably than in a configuration in which the pressure sensor 17 is installed to detect the pressure of the material transport pipe 6, the collector 3a, the upstream air suction pipe (upstream suction pipe) 7a, etc., which are paths communicating with the suction side of the suction blower 15. The pressure sensor 17 may be installed to detect the pressure of the air suction pipe (downstream suction pipe) 7b downstream of the dust collecting section 18 disposed in the air suction pipe 7 connecting the collector 3a constituting the transport destination and the suction blower 15. With this configuration, the pressure sensor 17 is installed in the path close to the suction blower 15, and the pressure can be detected stably as described above.

[0029] This pressure sensor 17 may be installed so as to be incorporated in an intermediate portion of the downstream suction pipe 7b, or may be installed in a pipe branching off from the downstream suction pipe 7b, for example, in a pipe branching off from an analog pressure gauge provided in the suction blower 15 so as to display the pressure on the suction side of the suction blower 15. Also, a display unit for the pressure sensor 17 may be provided on the control panel 10 described below or in the vicinity of the control panel 10 so that the detected value of the pressure sensor 17 can be easily confirmed. Also, the pressure sensor 17 may be provided in a plurality of locations. The pressure sensor 17 may be appropriately configured to output a signal corresponding to a threshold value set as described below. For example, when four threshold values ​​are set as described below, two dual-output pressure sensors 17 may be provided, or one digital pressure sensor 17 may be provided, or an appropriate number and type may be used according to the threshold value to be set. Instead of the pressure sensor 17 being provided to detect the pressure of the downstream suction pipe 7b, the pressure sensor 17 may be provided to detect the pressure of an appropriate location such as the air suction pipe (upstream suction pipe) 7a upstream of the dust collector 18, the collector 3a, or the material transport pipe 6.

[0030] The dust collecting section 18 is incorporated between the upstream suction pipe 7a and the downstream suction pipe 7b that constitute the air suction pipe 7. The dust collecting section 18 may include a filter section such as a bag filter or a pleated filter formed of various filter materials such as filter paper or filter cloth. The dust collecting section 18 may also include a cyclone separator or the like provided upstream of the filter section. The dust collecting section 18 may constitute a unitized air conveying device together with the suction blower 15. The suction blower 15 may be composed of a suitable blower or the like. An air introduction path or the like that introduces the atmosphere (outside air) through a suitable solenoid valve or the like may be connected to the suction side of the suction blower 15. With this configuration, in the case of so-called batch transport in which transport from the transport source 20 to the transport destination collector 3a is performed intermittently, the suction blower 15 can be continued to be started by opening the solenoid valve of the air introduction path when transport is stopped, and frequent ON / OFF of the suction blower 15 can be suppressed. In addition, a suitable silencer or the like that suppresses exhaust noise may be provided on the exhaust side (discharge side) of the suction blower 15. The suction air source is not limited to the suction blower 15, and may be a vacuum pump or the like.

[0031] The material transport device 1 is provided with a differential pressure gauge 19 that measures the pressure difference between the upstream path (upstream suction pipe) 7a and the downstream path (downstream suction pipe) 7b of the dust collecting section 18. With this configuration, the user can be made aware that the dust collecting section 18 (filter section) is clogged, and maintenance can be urged. In the illustrated example, the differential pressure gauge 19 is installed in a bypass path 7c that branches off from the upstream suction pipe 7a on the upstream side of the dust collecting section 18 and is connected to join the downstream suction pipe 7b on the downstream side of the dust collecting section 18. When a cyclone separator is provided in the dust collecting section 18, the bypass path 7c may be provided to connect the upstream side of the filter section downstream of the cyclone separator to the downstream side of the filter section. In other words, the differential pressure gauge 19 may be installed to measure the pressure difference between the upstream side and the downstream side of the filter section that constitutes the dust collecting section 18. Such a differential pressure gauge 19 may be an analog type differential pressure gauge 19 that displays the pressure difference, or a digital type differential pressure gauge 19 that can output the pressure difference. Similarly to the pressure sensor 17 described above, the display unit of the differential pressure gauge 19 may be installed on the control panel 10 described below or in the vicinity of the control panel 10 so that the detected value of the differential pressure gauge 19 can be easily confirmed. Note that a configuration in which such a differential pressure gauge 19 is not provided may also be used.

[0032] The control unit 11 is provided in an appropriate control panel 10 that is installed at a suitable location of the material transport device 1 or at a location separated from the material transport device 1. The control unit 11 includes a control circuit such as a CPU (Central Processing Unit) and executes basic operations and the like described below. The control unit 11 is connected to each part of the material transport device 1, including the blower drive unit 16, the pressure sensor 17, the differential pressure gauge 19, the inverter 26a of the supply side drive unit 26, and the like, via signal lines and the like. The control unit 11 may also be connected to the material sensor 28 of the receiving unit 27, the material sensor provided in the storage unit 21, and the material sensor provided in the first supply tank 3A, etc., which is the transport destination, via signal lines and the like. The start (ON) / stop (OFF) of the blower drive unit 16 is controlled by the control unit 11. The frequency of the inverter 26a of the supply side drive unit 26 is changed and controlled by the control unit 11, and the supply amount of the fixed quantity supply unit 24 is changed.

[0033] The control panel 10 is provided with an operation display unit 12 for setting, inputting, and displaying various settings. The control panel 10 is provided with a storage unit 13, which stores various programs such as setting conditions and input values ​​set and input by operating the operation display unit 12, control programs for executing basic operations described below, various pre-set operating conditions, various data tables, etc., and is composed of various memories such as ROM and RAM. The control panel 10 is also provided with an alarm unit 14. Such an alarm unit 14 may be an alarm lamp that notifies by light, or may be a buzzer or speaker that notifies by sound instead of or in addition to such a configuration. For example, if the differential pressure gauge 19 is a digital type that can output the pressure difference, the alarm unit 14 may be configured to notify if the pressure difference becomes a predetermined value or more. It is also possible to configure the control panel 10 without providing such an alarm unit 14.

[0034] Next, an example of a material transport method according to this embodiment will be described with reference to FIG. 3 as an example of a basic operation executed in the material transport apparatus 1 according to this embodiment configured as described above. The material transport method according to this embodiment is a method for pneumatically transporting powdered or granular material supplied from a constant quantity supply unit 24 provided at a transport source 20, via a material transport pipe 6, toward a transport destination (3a) communicating with a suction blower 15. This material transport method changes the supply amount of the constant quantity supply unit 24 based on a detection value of a pressure sensor 17 that detects the pressure in a path (6, 7) communicating with the suction side of the suction blower 15, including the material transport pipe 6. An example of a basic operation including such a material transport method, which will be described later, may be executed by controlling each unit by the control unit 11.

[0035] In this operation example, the control unit 11 reduces the supply amount of the constant-volume supply unit 24 when the detection value of the pressure sensor 17 falls below a low-pressure side threshold (Pl1, Pl2) that is lower than a preset reference pressure value Pr. On the other hand, the control unit 11 increases the supply amount of the constant-volume supply unit 24 when the detection value of the pressure sensor 17 exceeds a high-pressure side threshold (Pu1, Pu2) that is higher than the reference pressure value Pr. With this configuration, the reference pressure value Pr can be set to an appropriate value in advance according to the suction blower 15 selected according to the distance and pipe diameter of the path (6, 7) communicating with the suction side of the suction blower 15 including the material transport pipe 6, the required transport capacity, etc. Also, the low-pressure side threshold (Pl1, Pl2) and the high-pressure side threshold (Pu1, Pu2) can be set based on the reference pressure value Pr set in this way, so that the control can be simplified.

[0036] In this operation example, the control unit 11 reduces the supply amount of the constant-volume supply unit 24 when the detection value of the pressure sensor 17 falls below the low-pressure side threshold (Pl1, Pl2) and the preset low-pressure side delay time (T1, T2) has elapsed. On the other hand, the control unit 11 increases the supply amount of the constant-volume supply unit 24 when the detection value of the pressure sensor 17 exceeds the high-pressure side threshold (Pu1, Pu2) and the preset high-pressure side delay time (T3, T4) has elapsed. With this configuration, it is possible to suppress changes in the supply amount of the constant-volume supply unit 24 due to erroneous detection or disturbance. Also, in this operation example, the low-pressure side delay time (T1, T2) is shorter than the high-pressure side delay time (T3, T4). With this configuration, when the detection value of the pressure sensor 17 becomes low pressure side (high vacuum side), it is possible to relatively quickly reduce the supply amount of the constant-volume supply unit 24, and it is possible to effectively suppress the occurrence of blockage of the powdered granular material in the material transport pipe 6.

[0037] The reference pressure value Pr may be set in advance according to the capacity of the suction blower 15 selected according to the distance and pipe diameter of the route (6, 7) including the material transport pipe 6, the required transport capacity, etc., or may be set by accepting input from the operation display unit 12, etc. The low pressure side thresholds (Pl1, Pl2) and the high pressure side thresholds (Pu1, Pu2) may be set by accepting input from the operation display unit 12, etc., or, once the reference pressure value Pr is set, a value obtained by subtracting a predetermined value from the reference pressure value Pr may be automatically set as the low pressure side thresholds (Pl1, Pl2), and a value obtained by adding a predetermined value to the reference pressure value Pr may be automatically set as the high pressure side thresholds (Pu1, Pu2).

[0038] Specifically, in this operation example, a first low-pressure threshold Pl1 lower than the reference pressure value Pr and a second low-pressure threshold Pl2 lower than the first low-pressure threshold Pl1 are set as the low-pressure thresholds. Also, a first high-pressure threshold Pu1 higher than the reference pressure value Pr and a second high-pressure threshold Pu2 higher than the first high-pressure threshold Pu1 are set as the high-pressure thresholds. In addition, if the above-mentioned differential pressure gauge 19 is a digital type capable of outputting the pressure difference, control may be performed to sequentially correct the reference pressure value Pr, the low pressure side threshold values ​​(Pl1, Pl2), the high pressure side threshold values ​​(Pu1, Pu2), etc. according to the pressure difference.

[0039] The low-voltage side delay times (T1, T2) and the high-voltage side delay times (T3, T4) may be set in advance, or may be set by receiving an input from the operation display unit 12 or the like. Specifically, in this operation example, a first low-pressure side delay time T1 corresponding to a first low-pressure side threshold Pl1 and a second low-pressure side delay time T2 corresponding to a second low-pressure side threshold Pl2 are set as the low-pressure side delay time. The second low-pressure side delay time T2 is set shorter than the first low-pressure side delay time T1. With this configuration, when the detection value of the pressure sensor 17 falls below the second low-pressure side threshold Pl2, which is on the lower pressure side (high vacuum side), the supply amount of the constant quantity supply unit 24 can be quickly reduced. This makes it possible to effectively suppress the occurrence of blockage of the powdered granular material in the material transport pipe 6 due to oversupply.

[0040] Also, an example is shown in which a first high-pressure side delay time T3 corresponding to the first high-pressure side threshold Pu1 and a second high-pressure side delay time T4 corresponding to the second high-pressure side threshold Pu2 are set as the high-pressure side delay time. Also, the first high-pressure side delay time T3 is shorter than the second high-pressure side delay time T4. With this configuration, when the detection value of the pressure sensor 17 exceeds the second high-pressure side threshold Pu2, which is the higher pressure side (atmospheric pressure side), the supply amount of the constant-pressure supply unit 24 is immediately increased significantly. Therefore, if the detection value falls below the second high-pressure side threshold Pu2 within the second high-pressure side delay time T4, the supply amount of the constant-pressure supply unit 24 is maintained without change, and it is possible to effectively suppress the occurrence of blockage of the powdered material in the material transport pipe 6 due to an unnecessary increase in the supply amount. These delay times T1, T2, T3, and T4 may be set appropriately within a range of, for example, about 1 second to 60 seconds. The low-voltage side delay times (T1, T2) may be set appropriately within a range of, for example, about 1 second to 15 seconds, and the high-voltage side delay times (T3, T4) may be set appropriately within a range of, for example, about 15 seconds to 60 seconds. These delay times T1, T2, T3, and T4 may all be set to the same time, for example.

[0041] In the case where the low pressure side thresholds (Pl1, Pl2) and the high pressure side thresholds (Pu1, Pu2) are set in multiple stages (two stages in this operation example) as described above, the following control may be executed as shown in FIG. 3. Note that FIG. 3 illustrates only the transition of the detection value of the pressure sensor 17 and the frequency of the inverter 26a that is change-controlled, but the control unit 11 controls the above-mentioned units, and a transport mode is executed in which the powdered material is pneumatically transported from the transport source 20 to the transport destination (3a). For example, in the case of batch transport, when a material request signal is output from the material sensor of the first supply tank 3A that is the transport destination, the blower drive unit 16 of the suction blower 15 is started (or if an air introduction path as described above is provided and the blower drive unit 16 is in an activated state, the solenoid valve is closed), and the supply side drive unit 26 of the fixed quantity supply unit 24 is driven. The transport is not limited to this batch transport, and may be substantially continuous transport during the operation of the molding machine 2. 3 shows an example in which the detection value of pressure sensor 17 is the reference pressure value Pr and the frequency of inverter 26a starts transportation at the fourth frequency F4, but this is not limited to the example. The graph of the transition of the detection value of pressure sensor 17 shown in FIG. 3 is shown as an example for convenience of explanation, and in the case of batch transportation, for example, the detection value of pressure sensor 17 does not necessarily transition as shown in FIG. 3 within one batch transportation.

[0042] When the detection value of pressure sensor 17 falls below first low-pressure threshold Pl1 and the first low-pressure delay time T1 has elapsed, the frequency of inverter 26a is lowered by one step. In the illustrated example, the frequency of inverter 26a is lowered from the fourth frequency F4 to the third frequency F3. This reduces the rotation speed of screw 25 and decreases the supply amount of constant quantity supply unit 24. When the detection value of the pressure sensor 17 falls below the second low-voltage side threshold Pl2 and the second low-voltage side delay time T2 has elapsed, the frequency of the inverter 26a is lowered by several steps (or to the lowest step). In the illustrated example, the frequency of the inverter 26a is lowered by two steps from the third frequency F3 to the first frequency F1, which is the lowest step, but the present invention is not limited to this.

[0043] On the other hand, when the detection value of pressure sensor 17 exceeds first high pressure side threshold value Pu1 and first high pressure side delay time T3 has elapsed, the frequency of inverter 26a is increased by one step. In the illustrated example, the frequency of inverter 26a is increased from first frequency F1 to second frequency F2. This increases the rotation speed of screw 25 and the supply amount of constant quantity supply unit 24. When the detection value of the pressure sensor 17 exceeds the second high-side threshold value Pu2 and the second high-side delay time T4 has elapsed, the frequency of the inverter 26a is increased by one or more steps (for example, two steps). In the illustrated example, the frequency of the inverter 26a is increased by two steps from the second frequency F2 to the fourth frequency F4, but the present invention is not limited to this.

[0044] The above-mentioned basic operation is an example, and appropriate modifications can be made. For example, if the powdered or granular material is blocked in the material transport pipe 6, or if the path (6, 7) communicating with the suction side of the suction blower 15 including the material transport pipe 6 is damaged, even if the frequency of the inverter 26a is changed (the supply amount of the constant-volume supply unit 24 is changed) as described above, the detection value of the pressure sensor 17 may not shift (return) to the reference pressure value Pr side and may become abnormal. If the control unit 11 determines that such an abnormal state has occurred, it may operate the notification unit 14 or stop the material transport device 1. For example, if the state where the second high-pressure side threshold value Pu2 is exceeded continues for a predetermined time, it may be determined that an abnormal state has occurred, or if the state where the second low-pressure side threshold value Pl2 is exceeded continues for a predetermined time, it may be determined that an abnormal state has occurred. Furthermore, a third high-pressure threshold on the higher side than the second high-pressure threshold Pu2 and a third low-pressure threshold on the lower side than the second low-pressure threshold Pl2 may be set as thresholds for detecting an abnormality, and if the third high-pressure threshold is exceeded (or a predetermined time has passed since exceeding it), an abnormal state may be determined, and if the third low-pressure threshold is exceeded (or a predetermined time has passed since falling below it), an abnormal state may be determined. Also, if the material sensor of the collector 3a or the supply tank 3A, which is the destination of the transport, outputs a material request signal even after a predetermined transport time has passed, an abnormal state may be determined, or if an abnormality occurs in the current value of the suction blower 15 (blower driving unit 16), an abnormal state may be determined. As a mode for detecting such an abnormal state, various other modes can be adopted.

[0045] Furthermore, for example, in the case where the frequency of the inverter 26a can be changed steplessly, instead of the configuration in which the low pressure side thresholds (Pl1, Pl2) and the high pressure side thresholds (Pu1, Pu2) are set as described above, the frequency of the inverter 26a may be changed and controlled in a feedback controlled manner so that the detection value of the pressure sensor 17 becomes the reference pressure value Pr, or various other configurations may be adopted. The specific configuration of each part included in the material transport apparatus 1 according to this embodiment and the material transport method executed using the material transport apparatus 1 are not limited to the configurations described above, and various other modifications are possible. [Explanation of symbols]

[0046] 1 Material transport equipment 3a Collector (transport destination) 6 Material transport pipe 7 Air suction tube 7a Upstream suction pipe (upstream path of dust collection section) 7b Downstream suction pipe (path downstream of the dust collector, path connected to the suction side of the suction air source) 8. Crusher 9 Transport pipe 11 Control section 15 Suction blower (suction air source) 17 Pressure Sensor 18 Dust collection section 19 Differential pressure gauge 20 Origin of transportation 21 Storage section 24 Quantitative supply section T1 1st low-voltage side delay time (low-voltage side delay time) T2 Second low-voltage side delay time (low-voltage side delay time) T3 1st high-voltage side delay time (high-voltage side delay time) T4 Second high-side delay time (high-side delay time) Pl1 First low pressure threshold (low pressure threshold) Pl2 Second low pressure threshold (low pressure threshold) Pr Reference pressure value Pu1 First high-pressure side threshold (high-pressure side threshold) Pu2 Second high-pressure threshold (high-pressure threshold)

Claims

1. A material transport device that pneumatically transports powdered or granular material from a quantitative supply unit that is provided at a transport source and quantitatively supplies powdered or granular material to a transport destination that communicates with a suction air source through a material transport pipe, A material transport device characterized by comprising a pressure sensor that detects the pressure in a path connected to the suction side of the suction air source including the material transport pipe, and a control unit that changes and controls the supply amount of the constant quantity supply unit based on the detection value of the pressure sensor.

2. In claim 1, The control unit reduces the supply amount of the fixed quantity supply unit when the detection value of the pressure sensor falls below a low pressure side threshold that is lower than a predetermined reference pressure value, and increases the supply amount of the fixed quantity supply unit when the detection value of the pressure sensor exceeds a high pressure side threshold that is higher than the reference pressure value.

3. In claim 2, The control unit reduces the supply amount of the constant-volume supply unit when the detection value of the pressure sensor falls below the low-pressure side threshold and a preset low-pressure side delay time has elapsed, and increases the supply amount of the constant-volume supply unit when the detection value of the pressure sensor exceeds the high-pressure side threshold and a preset high-pressure side delay time has elapsed.

4. In claim 3, A material transport apparatus, wherein the low pressure side delay time is shorter than the high pressure side delay time.

5. In any one of claims 1 to 4, The pressure sensor is positioned to detect pressure in a passage adjacent to the suction air source.

6. In any one of claims 1 to 4, the pressure sensor is installed so as to detect a pressure in an air suction pipe downstream of a dust collecting unit disposed in the air suction pipe connecting the transport destination and the suction air source; A material transport device comprising: a differential pressure gauge for measuring a pressure difference between the upstream path and the downstream path of the dust collecting section.

7. In any one of claims 1 to 4, A material transport device characterized in that a transport pipe for transporting powdered or granular material from a plurality of pulverizers is connected to the storage section constituting the transport source.

8. A material transport method for pneumatically transporting powdered or granular material from a quantitative supply unit that is provided at a transport source and supplies a quantitative amount of powdered or granular material through a material transport pipe to a transport destination that is connected to a suction air source, comprising: A material transport method, comprising: changing the supply amount of the constant-quantity supply unit based on a detection value of a pressure sensor that detects the pressure in a path communicating with the suction side of the suction air source, including the material transport pipe.

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