Powder supply device

Abstract

To provide a technique capable of controlling so as to supply a fixed amount of powder.SOLUTION: A powder supply device includes a storage that stores powder, a supply duct connected to the storage, a nozzle that is disposed in the storage, has flexibility, injects air into the storage, and supplies the air and the powder from the supply duct, a measurer that measures a weight of the storage, and a controller that controls an injection time of the air injected by the nozzle based on the weight measured by the measurer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a powder feeder. [Background technology]

[0002] Patent Document 1 discloses an apparatus for supplying powder to a dust collector. This apparatus includes a hopper for storing powder, a supply duct for supplying the powder in the hopper to the dust collector, and a flexible nozzle disposed within the hopper for injecting air into the hopper. The nozzle has a free end at its tip, and moves around within the hopper in reaction to the injection, stirring the hopper and stirring up the powder. The stirred-up powder is then supplied to the dust collector together with air through the supply duct. The powder supplied to the dust collector is mixed with the dust, reducing the dust's ignition potential. The nozzle is controlled to inject air for a fixed period of time at a fixed interval. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-100212 Summary of the Invention [Problem to be solved by the invention]

[0004] In the device described in Patent Document 1, the distance between the nozzle and the top surface of the powder stored in the hopper changes depending on the amount of powder stored in the hopper. Therefore, in the device described in Patent Document 1, the amount of powder that is blown up changes depending on the amount of powder stored. Because the amount of powder supplied changes depending on the amount of powder stored in the hopper, the device described in Patent Document 1 may not be able to supply a fixed amount of powder to the dust collector. The present disclosure provides a technology that can control the supply of a fixed amount of powder. [Means for solving the problem]

[0005] A powder supplying device according to one aspect of the present disclosure includes a storage section for storing powder, a supply duct connected to the storage section, a flexible nozzle disposed within the storage section for injecting air into the storage section and supplying the air and powder from the supply duct, a measuring section for measuring the weight of the storage section, and a control section for controlling the injection time of the air injected by the nozzle based on the weight measured by the measuring section. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to control the supply of a fixed amount of powder. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing an example of a dust collection system equipped with a powder supplying device according to an embodiment. [Figure 2] Figure 2(A) is a time chart showing the relationship between the control time of the solenoid valve, the powder weight, and the supply amount when the injection time is controlled at a constant time, and Figure 2(B) is a time chart showing the relationship between the control time of the solenoid valve, the powder weight, and the supply amount when the injection time is controlled by changing the injection time. [Figure 3] FIG. 3 is a time chart showing the relationship between the control time of the solenoid valve, the weight measured by the load cell, and the sampled weight. [Figure 4] FIG. 4 is a flowchart showing the powder supply method. [Figure 5] Figure 5(A) is a graph showing the change in powder weight over time and the change in supply rate over time in the example, and Figure 5(B) is a graph showing the change in powder weight over time and the change in supply rate over time in the comparative example. [Figure 6] FIG. 6 is a schematic diagram showing an example of a dust collection system provided with a powder supplying device according to another embodiment. [Figure 7] FIG. 7 is a diagram schematically illustrating an end face of the ejector. [Figure 8]FIG. 8 is a time chart showing the relationship between the control time of the electromagnetic valve, the weight measured by the load cell, and the sampled weight in a powder supplying device according to another embodiment. [Figure 9] FIG. 9 is a schematic diagram showing an example of a dust collection system provided with a powder supplying device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicate descriptions will be omitted. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper," "lower," "left," and "right" are based on the illustrated state and are for convenience only.

[0009] [Configuration of powder supply device] FIG. 1 is a schematic diagram illustrating an example of a dust collection system equipped with a powder supplying device according to an embodiment. As shown in FIG. 1, the dust collection system 100 includes a powder supplying device 1 and a dust collector 2. The powder supplying device 1 is applied to the dust collector 2, which is installed in, for example, a factory. The dust collector 2 collects dust in the air using a filter. The dust is a powder that is fine enough to float in the air and includes fumes generated during laser processing, plasma processing, welding, and the like. The filter may become charged due to the adhesion of charged dust or friction generated when the dust comes into contact with the filter. Because static electricity can cause ignition, the powder supplying device 1 supplies an inert powder to the dust collector 2, and mixing the inert powder with the dust reduces ignition potential.

[0010] The powder supplying device 1 includes a hopper 10 (an example of a storage section). The hopper 10 stores powder P. The powder P is, for example, an inert powder. As a specific example, the powder P is calcium carbonate or calcium hydroxide powder. The hopper 10 has a compressed air inlet 10a and an outlet 10b. An air source 11 is connected to the compressed air inlet 10a via a pipe 12. Thus, compressed air is supplied from the air source 11 via the pipe 12 into the inside of the hopper 10.

[0011] The powder supplying device 1 includes a nozzle 13 disposed within a hopper 10. The nozzle 13 is a flexible cylindrical member. The nozzle 13 is made of, for example, nylon, polyurethane, or silicone. The end of the nozzle 13 is connected to a compressed air inlet 10a, through which compressed air is supplied. The tip of the nozzle 13 is a free end, and sprays the compressed air into the hopper 10. At this time, the nozzle 13 moves irregularly within the hopper 10 (in a so-called turbulent state) due to the reaction force of the spray, stirring the inside of the hopper 10. This causes the accumulated powder P to fly up. The flexibility of the nozzle 13 allows it to fly up even powder that accumulates in the corners of the hopper 10. The raised powder P is then discharged to the outside together with air from the discharge outlet 10b of the hopper 10.

[0012] The powder supplying device 1 includes a supply duct 14 connected to a hopper 10. An end of the supply duct 14 is connected to an outlet 10b of the hopper 10, and an end of the supply duct 14 is connected to the dust collector 2. The powder P stored in the hopper 10 passes through the supply duct 14 and is supplied to the dust collector 2.

[0013] A solenoid valve 15 is provided in the piping 12. The solenoid valve 15 is controlled to open and close by a control unit 16. This changes the amount and timing of compressed air introduced. The control unit 16 has a PLC (Programmable Logic Controller) 161 and a signal converter 162. The PLC is a device that has a processor, memory, display, input / output unit, etc. The signal converter 162 is a device that converts sensor output, etc. into an electrical signal, etc.

[0014] The control unit 16 controls the injection time of air injected by the nozzle 13 based on the weight of the hopper 10. The hopper 10 is supported via a load cell 17 (an example of a measurement unit). The load cell 17 outputs a sensor signal related to the weight of the hopper 10 to the control unit 16. A signal converter 162 of the control unit 16 converts the sensor signal of the load cell 17 into a voltage signal or the like. The PLC 161 acquires the weight of the hopper 10 based on the voltage signal. The PLC 161 controls the opening and closing timing and opening and closing time of the solenoid valve 15 based on the measured weight of the hopper 10.

[0015] [Details of the control unit operation] Figure 2(A) is a time chart showing the relationship between the control time of the solenoid valve, the powder weight, and the supply amount when the injection time is controlled at a constant time, and Figure 2(B) is a time chart showing the relationship between the control time of the solenoid valve, the powder weight, and the supply amount when the injection time is controlled by changing the injection time.

[0016] 2A, when the control unit 16 controls the injection time of the solenoid valve 15 for a fixed time and at fixed intervals, the powder P is supplied over time, and the powder weight decreases (curve L1 in the figure). When the amount of powder P stored in the hopper decreases, the distance between the top surface of the stored powder P and the nozzle increases, and the amount of powder that is blown up decreases. As a result, the supply amount per unit time (hereinafter also referred to as the supply rate) decreases over time, and there is a risk that a fixed amount of powder P cannot be supplied to the dust collector 2.

[0017] For this reason, the control unit 16 controls the spray time of the nozzle 13 to realize the supply of a fixed amount of powder P. Supplying a fixed amount of powder P means that the amount of powder P supplied per unit time is constant. In other words, supplying a fixed amount of powder P means that the supply speed of powder P is constant. As shown in FIG. 2(B), the control unit 16 sets a short spray time when the weight of powder P is large, and gradually lengthens the spray time as the weight of powder P decreases (straight line L1 in the figure). This makes it possible to realize the supply of a fixed amount of powder P as surrounded by the dashed line in the figure.

[0018] The control unit 16 may calculate the supply rate of the powder P based on the weight of the powder P before and after injection and the injection time, and control the next injection time by comparing the calculated supply rate with a target supply rate. The target supply rate is a value preset by an operator or the like. The control unit 16 records the measurement results of the load cell 17 along with the time in a storage device. The control unit 16 also records the injection time, i.e., the opening and closing time of the solenoid valve 15, along with the time in the storage device. This allows the control unit 16 to use the weight of the powder P before and after injection and the injection time in calculations to calculate the supply rate. The control unit 16 determines the injection time so that the calculated supply rate approaches the target supply rate.

[0019] If the measured supply speed is greater than the target supply speed, the control unit 16 may set the next injection time to be shorter than the current injection time by a predetermined time. The predetermined time is a time that is set as appropriate. If the measured supply speed is equal to or less than the target supply speed, the control unit 16 may set the next injection time to be longer than the current injection time by a predetermined time. The predetermined time is a time that is set as appropriate. If the measured supply speed is within a predetermined range that includes the target supply speed, the control unit 16 may set the next injection time without changing the current injection time. The predetermined range is a speed range that is set as appropriate. By setting the predetermined range, the control unit 16 can perform control so that the supply speed more easily converges to the target supply speed.

[0020] The control unit 16 can display the determined injection time, the calculated supply speed, etc. on a display, thereby enabling the operator to confirm that the powder supplying device 1 is able to supply a fixed amount of powder P.

[0021] Because powder P is lightweight, the change in weight of hopper 10 per injection is small and may be below the measurable limit of load cell 17. For this reason, control unit 16 may measure the weight of hopper 10 at a cycle in which multiple injections are performed. Furthermore, because nozzle 13 moves around in reaction when powder P is injected, there is a risk that the measurement result of load cell 17 may contain noise. For this reason, control unit 16 may stop the injection of air from nozzle 13 while load cell 17 is measuring the weight of hopper 10. The period during which load cell 17 is measuring the weight of hopper 10 refers to the period during which data is sampled as the measurement time by load cell 17.

[0022] FIG. 3 is a time chart showing the relationship between the control time of the solenoid valve, the weight measured by the load cell, and the sampled weight. As shown in FIG. 3, the control unit 16 may perform multiple injections at a determined injection time. In the example shown in FIG. 3, a total of four injections are performed in a period T1. The period T1 includes an injection period t1 and a stop period t2. During the injection period t1, the nozzle 13 moves around, so the measurement by the load cell 17 contains noise. During the stop period t2, the nozzle 13 is stopped, so the measurement by the load cell 17 does not contain noise. Therefore, the control unit 16 samples the data output during the stop period t2 and calculates the weight measured in a measurement period T2, which includes four periods T1, by averaging the sampled data. A sampled weight W is calculated for each measurement cycle SY, which is the measurement period T2 plus a calculation time T3. n For example, in the previous measurement cycle, the sampling weight is W n-1 and in the next measurement cycle, the sampling weight is W n+1 The control unit 16 can reduce noise caused by the nozzle 13 while appropriately detecting the change in weight of the powder P by performing the calculation as shown in FIG.

[0023] [Powder supply device operation (powder supply method)] Fig. 4 is a flowchart showing the powder supplying method. The flowchart shown in Fig. 4 is started by the control unit 16 when the hopper 10 is filled with powder P and an operation command is given by an operator.

[0024] In step S10, the control unit 16 measures the initial weight of the hopper 10. The control unit 16 measures the weight of the hopper 10 based on a signal from the load cell 17. Next, in step S12, the control unit 16 opens the solenoid valve 15 a predetermined number of times for a predetermined period of time. As a result, compressed air is blown into the hopper 10, and the compressed air and powder P are fed from the hopper 10 into the dust collector 2.

[0025] Next, in step S14, control unit 16 measures the weight of hopper 10. Control unit 16 measures the weight of hopper 10 based on the signal from load cell 17. Then, in step S16, control unit 16 calculates the difference (weight difference) between the initial weight measured in step S10 and the weight measured in step S14. Then, control unit 16 calculates the supply speed based on the weight difference (absolute value). As a specific example, control unit 16 calculates the supply speed by dividing the weight difference by the supply time.

[0026] Next, in Step S18, the control unit 16 determines whether the supply rate calculated in Step S16 is greater than the target supply rate. If it is determined that the calculated supply rate is greater than the target supply rate (Step S18: YES), the control unit 16 decreases the next injection time in Step S20. If it is determined that the calculated supply rate is not greater than the target supply rate (Step S18: NO), the control unit 16 increases the next injection time in Step S22.

[0027] When step S20 or step S22 is completed, the control unit 16 determines whether or not a termination condition is met. The termination condition is a condition for stopping the powder supply and is set in advance by an operator or the like. For example, the termination condition may include receiving an instruction to terminate from an operator, reaching a specified time, or stopping the dust collector 2. If it is determined that the termination condition is not met (step S24: NO), the process returns to step S12, and the processes from step S12 to step S24 are executed again. If it is determined that the termination condition is met (step S24: YES), the flowchart shown in FIG. 4 ends.

[0028] [Summary of the embodiment] In the powder supplying device 1, powder P in a hopper 10 is raised by a flexible nozzle 13 disposed in the hopper 10 and is then thrown together with air through a supply duct 14 into the dust collector 2. The weight of the hopper 10 is measured by a load cell 17. The injection time of air injected by the nozzle 13 is controlled based on the measured weight. Since the powder supplying device 1 can control the injection time of air according to the weight of the hopper 10, it can be controlled so that a fixed amount of powder P is supplied to the dust collector 2.

[0029] [Variations] Although various exemplary embodiments have been described above, various omissions, substitutions, and modifications may be made without being limited to the above-described exemplary embodiments.

[0030] For example, in the embodiment, the powder supplying device 1 is shown as having two nozzles, but it may have one nozzle, or three or more nozzles. Also, the nozzles may be branched in the middle so that there are more nozzles at the tip than at the end.

[0031] The control unit 16 is not limited to a PLC or a signal converter as long as it can process the sensor output and control the ejection time of the nozzle 13. The control unit 16 may be configured as a computer system including, for example, a central processing unit (CPU), memories such as a random access memory (RAM) and a read only memory (ROM), input / output devices such as a touch panel, a mouse, a keyboard, and a display, and a communication device such as a network card. The control unit 16 may also control the flow rate and pressure of the air ejected by the nozzle 13.

[0032] In the embodiment, an example has been shown in which the weight of the hopper 10 is measured by the load cell 17, but the hopper 10 may be supported by an elastic body such as a spring (another example of a measuring unit) and the weight may be measured. Alternatively, the weight of the powder may be measured directly by a sensor (another example of a measuring unit) such as an image sensor arranged in the hopper 10, and the weight may be measured by adding this to the weight of the hopper 10 when empty. In other words, "measuring the weight of the hopper 10" includes directly measuring the weight of the powder.

[0033] The powder supplying device 1 may be applied to a duct that transports airborne dust, for example, located in a factory. The powder supplying device 1 is connected to the duct in place of the dust collector 2. Since dust accumulation in the duct can cause ignition due to static electricity, the powder supplying device 1 supplies inert powder into the duct and mixes the inert powder with the dust to reduce ignition potential.

[0034] [Feed rate evaluation] Below, a description will be given of examples carried out to evaluate the supply speed using the powder supplying device 1. However, the present disclosure is not limited to these examples.

[0035] (Example) Powder P was fed into the dust collector 2 using a powder feeder 1. While the accuracy of the weight of the hopper 10 was improved by sampling as shown in Figure 3, quantitative control was performed as shown in Figure 2 (B). The conditions were as follows: Powder P: Calcium carbonate powder Period T1: 30 seconds Measurement cycle SY: 180 seconds Target supply speed TP: 0.1g / s

[0036] (Comparative Example) Powder P was fed into the dust collector 2 using a powder feeder 1. As shown in Figure 3, sampling was carried out to improve the accuracy of the weight of the hopper 10, and the injection time was set to a fixed time as shown in Figure 2 (A). The other conditions were the same as those in the example.

[0037] FIG. 5A is a graph showing the change in powder weight over time and the change in supply rate over time in the example, and FIG. 5B is a graph showing the change in powder weight over time and the change in supply rate over time in the comparative example. As shown in FIGS. 5A and 5B, in both the example and the comparative example, the powder weight decreased over time, decreasing by approximately 6 kg within 20 hours after the device was started. As shown in FIG. 5A, in the powder supply device of the example, the supply rate of powder P was maintained at a value close to the target supply rate TP within 20 hours after the device was started. In contrast, in the powder supply device of the comparative example, the supply rate was two to three times the target supply rate TP within several hours after the device was started. Within 10 hours after the device was started, the supply rate was greater than the target supply rate TP, and within 10 hours after the device was started, the supply rate was less than the target supply rate TP. In this way, it was confirmed that the powder supplying device 1 according to the example can be controlled to supply a fixed amount of powder.

[0038] Hereinafter, a powder supplying device according to another embodiment will be described with reference to Fig. 6, Fig. 7, and Fig. 8. Fig. 6 is a schematic diagram showing an example of a dust collection system equipped with a powder supplying device according to another embodiment. The powder supplying device 1A shown in Fig. 6 includes a supply duct 14A instead of the supply duct 14. The following description of the powder supplying device 1A will focus on the differences between the powder supplying device 1A and the powder supplying device 1, and redundant description will be omitted.

[0039] The powder supplying device 1A further includes a housing 18. The solenoid valve 15 and the control unit 16 are disposed inside the housing 18. The load cell 17 is disposed on the housing 18. In the powder supplying device 1A, the housing 18, the load cell 17, and the hopper 10 are disposed in that order from the bottom up.

[0040] The supply duct 14A has an ejector 20. The ejector 20 uses compressed air to generate an airflow that flows from the powder supplying device 1A to the dust collector 2. In the example shown in FIG. 6, the supply duct 14A further has a first duct 20a and a second duct 20b. The first duct 20a connects the outlet 10b of the hopper 10 to the ejector 20. The second duct 20b connects the ejector 20 to the dust collector 2. The ejector 20 is configured to inject a driving flow into the second duct 20b. The ejector 20 may be fixed to the housing 18.

[0041] 7 is a diagram schematically illustrating an end face of an ejector. As shown in FIG. 7, the ejector 20 includes a suction unit 21, a supply unit 22, and an air nozzle 23. The suction unit 21 is connected to the hopper 10. For example, the suction unit 21 is connected to the hopper 10 via a first duct 20a. The supply unit 22 is configured to supply air and powder P. For example, the supply unit 22 is connected to the dust collector 2 via a second duct 20b, and is configured to supply air and powder P to the dust collector 2 via the second duct 20b.

[0042] The air nozzle 23 includes an opening 24 configured to inject the driving flow toward the supply unit 22. The driving flow generates negative pressure in the suction unit 21. For example, the air nozzle 23 includes a compressed air inlet 23a. The compressed air inlet 23a is connected to the opening 24 of the air nozzle 23. The compressed air inlet 23a is connected to the air source 11 via piping 19. This allows compressed air to be supplied to the opening 24 of the air nozzle 23, and the driving flow is injected from the opening 24. A solenoid valve 15A is provided in the piping 19. The solenoid valve 15A is controlled to open and close by the control unit 16. This changes the amount and timing of the introduction of compressed air. The control unit 16 may control the amount of compressed air supplied to the inlet 23a of the air nozzle 23 so that it is greater than the amount of compressed air supplied to the inlet 10a of the hopper 10. In this case, negative pressure is more likely to be generated in the suction unit 21.

[0043] According to the powder supplying device 1A, a driving flow is injected from the ejector 20 in the supply duct 14A. The driving flow causes the powder P remaining in the portion of the supply duct 14A between the ejector 20 and the dust collector 2 to be supplied from the supply duct 14A to the dust collector 2. Therefore, according to the powder supplying device 1A, the amount of the powder P remaining in the supply duct 14A is reduced. As a result, the powder supplying device 1A can stably supply a fixed amount of the powder P.

[0044] In the example shown in FIG. 7, the suction unit 21, the air nozzle 23, and the supply unit 22 define a flow path F extending in one direction AX. The air nozzle 23 is disposed between the suction unit 21 and the supply unit 22. In the one direction AX, the suction unit 21, the air nozzle 23, and the supply unit 22 are arranged in that order. The opening 24 includes a slit S extending in a circumferential direction about the flow path F on an inner surface 23d of the air nozzle 23, which defines a portion of the flow path F. Compressed air supplied from the inlet 23a is supplied to the slit S through a groove 23b extending in a circumferential direction about the flow path F. The inner surface 21a of the suction unit 21, which defines a portion of the flow path F, includes a tapered surface whose diameter increases toward the open end that sucks in the powder P. The inner surface 22a of the supply unit 22, which defines a portion of the flow path F, includes a tapered surface whose diameter increases toward the open end that supplies the powder P. Note that the configuration of the ejector is not limited to the example shown in FIG. 7. The suction unit 21 may be disposed between the air nozzle 23 and the supply unit 22. In this case, the powder P and air can be sucked in a direction intersecting the direction in which the driving flow flows from the air nozzle 23 toward the supply unit 22.

[0045] The slit S is formed by a first tapered surface 24a and a second tapered surface 24b. The first tapered surface 24a and the second tapered surface 24b are each inclined in a direction that forms a driving flow in which compressed air supplied through the groove 23b is ejected toward the supply unit 22. The first tapered surface 24a is adjacent to the supply unit 22. The second tapered surface 24b faces the first tapered surface 24a in the one direction AX. In the ejector 20, the powder P in the flow path F flows along the one direction AX, so the ejector 20 can stabilize the supply of a fixed amount of powder P. The slit S allows the driving flow to be ejected from the periphery of the flow path F, thereby stabilizing the driving flow.

[0046] The control unit 16 may be configured to control the air nozzle 23 not to spray the driving flow while the load cell 17 is measuring the weight of the hopper 10. FIG. 8 is a time chart showing the relationship between the control time of the solenoid valves 15 and 15A, the measured weight of the load cell 17, and the sampled weight in the powder supplying device 1A. In the example shown in FIG. 8, the air nozzle 23 sprays the driving flow at a spray cycle T4. The spray cycle T4 is the period after the calculation time T3. The control unit 16 may be configured to spray the driving flow from the air nozzle 23 after the load cell 17 measures the weight of the hopper 10. By controlling the spray of the driving flow as shown in FIG. 8, the control unit 16 can appropriately capture changes in the weight of the powder P while reducing noise caused by the air nozzle 23.

[0047] Referring again to FIG. 6, the configuration of the powder supplying device 1A will be described. The hopper 10 may have a supply port 10c and a lid 10d. The supply port 10c is connected to the inside of the hopper 10. The lid 10d is configured to be able to open and close the supply port 10c. For example, an operator opens the lid 10d and fills the hopper 10 with powder P through the supply port 10c. The control unit 16 may be configured to control the air nozzle 23 to spray a driving flow from the opening 24 when the supply port 10c is not closed by the lid 10d. For example, the hopper 10 may further have an opening / closing sensor that detects the opening and closing of the lid 10d. For example, the opening and closing of the solenoid valve 15A may be configured to be linked to the opening and closing of the lid 10d.

[0048] When the driving flow is sprayed from opening 24 of air nozzle 23, a negative pressure is generated in suction section 21, and powder P and air are sucked in through outlet 10b. Therefore, when lid 10d is opened and powder P is filled into hopper 10, powder P and air are sucked in through outlet 10b, so powder supplying device 1A can prevent powder P from scattering within hopper 10.

[0049] A powder supplying device according to yet another embodiment will be described below with reference to Fig. 9. The powder supplying device 1B shown in Fig. 9 further includes a pressure regulator 30 in addition to the configuration of the powder supplying device 1A shown in Fig. 6. The following description of the powder supplying device 1B will focus on the differences from the powder supplying device 1A, and overlapping descriptions will be omitted.

[0050] 9, a pipe extending from an air source 11 branches into two pipes at a branching point 12A. One pipe is a pipe 12 that supplies air to a hopper 10, and the other pipe is a pipe 19 that supplies air to an ejector 20.

[0051] The pressure regulator 30 is provided in the pipe 12. As a more specific example, the pressure regulator 30 is provided between the solenoid valve 15 provided in the pipe 12 and the branching portion 12A. The pressure regulator 30 is connected to the control unit 16, and is configured to be able to adjust the pressure of the compressed air supplied to the nozzle 13 (see FIG. 1 ) based on a control signal from the control unit 16.

[0052] When attempting to supply a small amount of powder P by controlling the injection time as in the above-described embodiment, even if the injection time is made sufficiently short, the amount of powder P supplied may be too large, and the target supply rate may not be achieved.

[0053] Therefore, in addition to the injection time, the control unit 16 also controls the pressure (injection pressure) of the air injected from the nozzle 13. For example, in the flowchart of Fig. 4, if the supply speed calculated in step S16 is higher than the target supply speed (step S18: YES), the control unit 16 not only reduces the injection time (step S20), but also controls the pressure regulator 30 to reduce the pressure of the compressed air supplied to the nozzle 13 if, for example, the injection time has reached a predetermined lower limit value.

[0054] When the pressure of the supplied air decreases, the reactive force of the spray from nozzle 13 decreases, and the movement of nozzle 13 within hopper 10 becomes gentler. This reduces the amount of powder P stirred and stirred up within hopper 10, making it possible to further reduce the amount of powder P supplied from supply duct 14A. In this way, according to powder supply device 1B, control unit 16 uses both the spray time and the spray pressure as control parameters, thereby enabling more accurate control of the supply amount of powder P and making it possible to further stabilize the supply of a fixed amount.

[0055] [Summary of the embodiments of the present disclosure] The present disclosure includes the following aspects.

[0056] (Clause 1) A powder supply device comprising: a storage section for storing powder; a supply duct connected to the storage section; a flexible nozzle disposed within the storage section for injecting air into the storage section and supplying the air and the powder from the supply duct; a measuring section for measuring the weight of the storage section; and a control section for controlling the injection time of the air injected by the nozzle based on the weight measured by the measuring section.

[0057] In this powder supplying device, the powder in the storage unit is blown up by a flexible nozzle located inside the storage unit and then injected to the outside through a supply duct together with air. The weight of the storage unit is measured by a measuring unit. The injection time of the air injected by the nozzle is controlled based on the measured weight. Since this powder supplying device can control the injection time of the air according to the weight of the storage unit, it can be controlled to supply a fixed amount of powder.

[0058] (Clause 2) In the powder supplying device described in Clause 1, the control unit may stop the injection of air from the nozzle while the measuring unit is measuring the weight of the storage unit. In this case, the powder supplying device can prevent the injection of air from the nozzle from affecting the measurement of the weight of the storage unit, and therefore can properly measure the weight of the storage unit.

[0059] (Clause 3) In the powder supplying device described in clause 1 or 2, the control unit may cause the measuring unit to measure the weight of the storage unit after causing the nozzle to perform the process of injecting air multiple times. In this case, the powder supplying device can properly measure the weight of the storage unit even if a change in weight of the storage unit due to a single injection is below the detection limit of the measuring unit.

[0060] (Clause 4) In the powder supplying device described in any one of clauses 1 to 3, the control unit may calculate a supply rate of the powder based on the weight measured by the measuring unit, and control a spray time of the air sprayed by the nozzle so that the calculated supply rate approaches a preset target supply rate. In this case, the powder supplying device can adjust the spray time so that the supply rate of the powder becomes the target supply rate.

[0061] (Clause 5) In the powder supplying device described in Clause 4, the control unit may further control the injection pressure of the air injected by the nozzle so that the calculated supply rate approaches the target supply rate. In this case, the powder supplying device can adjust the injection pressure so that the supply rate of the powder becomes the target supply rate.

[0062] (Clause 6) In the powder supplying device described in any one of clauses 1 to 5, the supply duct may have an ejector including a suction section connected to the reservoir, a supply section configured to supply the air and the powder, and an air nozzle including an opening configured to inject a driving flow toward the supply section to generate negative pressure in the suction section. In this case, the driving flow of the ejector supplies the powder remaining in the supply duct. Therefore, the amount of powder remaining in the supply duct is reduced, and the powder supplying device can stably supply a fixed amount of powder.

[0063] (Clause 7) In the powder supplying device described in Clause 6, the storage unit may have a supply port communicating with the interior of the storage unit and a lid configured to open and close the supply port, and the control unit may be configured to control the air nozzle to spray the driving flow from the opening when the supply port is not closed by the lid. In this case, when the lid is opened and the storage unit is filled with powder, the powder and air are sucked from the storage unit into the suction unit, so the powder supplying device can suppress scattering of powder within the storage unit. [Explanation of symbols]

[0064] 1, 1A, 1B... powder supply device, 2... dust collector, 10... hopper (an example of a storage section), 10c... supply port, 10d... lid body, 13... nozzle, 14, 14A... supply duct, 16... control section, 17... load cell (an example of a measurement section), 20... ejector, 21... suction section, 22... supply section, 23... air nozzle, 23d... inner surface, 24... opening, 30... pressure regulator, F... flow path, AX... one-way

Claims

1. a storage section for storing powder; a supply duct connected to the reservoir; a nozzle disposed within the reservoir, the nozzle having flexibility, for injecting air into the reservoir and supplying the air and the powder from the supply duct; A measuring unit that measures the weight of the storage unit; a control unit that controls an injection time of the air injected by the nozzle based on the weight measured by the measuring unit; A powder supplying device comprising:

2. The powder supplying device according to claim 1 , wherein the control unit stops the injection of the air from the nozzle while the measuring unit is measuring the weight of the storage unit.

3. The powder supplying device according to claim 1 , wherein the control unit causes the measuring unit to measure the weight of the reservoir after causing the nozzle to perform the process of injecting air a plurality of times.

4. 3. The powder supplying device according to claim 1, wherein the control unit calculates a supply rate of the powder based on the weight measured by the measuring unit, and controls an injection time of the air injected by the nozzle so that the calculated supply rate approaches a predetermined target supply rate.

5. The powder supplying device according to claim 4 , wherein the control unit further controls an injection pressure of the air injected by the nozzle so that the calculated supply speed approaches the target supply speed.

6. The supply duct a suction unit connected to the storage unit; a supply unit configured to supply the air and the powder; an air nozzle including an opening configured to inject a driving flow toward the supply unit, the driving flow generating a negative pressure in the suction unit; The powder feeding apparatus of claim 1 , further comprising an ejector comprising:

7. The storage section is a supply port communicating with the storage portion; a lid configured to be able to open and close the supply port, 7. The powder supplying device according to claim 6, wherein the control unit is configured to control the driving flow to be sprayed from the opening of the air nozzle when the supply port is not closed by the lid.

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