Powder / granular material supply device and loss-in-weight control method

Abstract

To provide a continuous type powder / granular material supply device preventing loss-in-weight control for making the discharge amount of a powder / granular material per unit time constant from pausing.SOLUTION: A powder / granular material supply device has a main feeder 1 and a sub-feeder 2, and at the time of normal operation, performs feedback control of referring to the reduced amount at which the sum of the weight of the main feeder 1 and the weight of the sub-feeder 2 is reduced by the discharge of a powder / granular material so as to approach a discharge rate of the powder / granular material set in advance. Though the powder / granular material is replenished from the outside to the sub-feeder 2 when the powder / granular material stored in a sub-hopper 21 is reduced and the replenishment is required, the pausing time of the loss-in-weight control can be eliminated by switching so as to perform the feedback control by referring to only the reduced amount of the weight of the main feeder 1 in this time zone.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a powdered material supplying device and a loss-in-weight control method, and more particularly to a powdered material supplying device operable under loss-in-weight control and a loss-in-weight control method. [Background technology]

[0002] Powder and granular material supplying devices that supply a fixed amount of powder and granular material are already widely known. These powder and granular material supplying devices include a hopper for temporarily storing the powder and granular material, a discharge unit having a screw or the like for discharging the powder and granular material from the hopper, a weighing unit on which these devices are mounted, and a control unit. The weighing section is capable of measuring the weight of the powder stored in the hopper section and the discharge section while the discharge section discharges the powder. The amount of weight reduction (discharged weight of powder) is measured, and the screw rotation speed of the discharge section is controlled (adjusted) to keep the discharged weight per hour (i.e., discharge weight speed) constant. This control method is generally called loss-in-weight control.

[0003] In this type of powder / granular material supplying device, when the powder / granular material stored in the hopper decreases and runs out, it becomes necessary to replenish the powder / granular material from the outside. While replenishment of the powder / granular material from the outside is being performed, the weight of the powder / granular material supplying device increases, making it impossible to measure the discharge amount. As a result, it becomes impossible to perform the original discharge amount control of the powder / granular material (loss-in-weight control). However, it is necessary to continue the continuous discharge of the powder / granular material supplying device.

[0004] For this reason, the following method is adopted. The technology shown in Patent Document 1, when the powder in the storage section is about to run out, rotates the screw in the discharge section at the same constant speed as before (so-called locked operation, which operates with the number of rotations fixed) to continue the discharge operation while replenishing the powder in the hopper. In other words, the loss-in-weight control is temporarily stopped. Also, in order to reduce the frequency of temporary non-control of the discharge amount, it becomes necessary to enlarge the hopper of the powder / granular material supplying device.

[0005] The technology shown in Patent Document 2 involves operating two powder / granular material supplying devices side by side in alternating operation in order to perform continuous loss-in-weight control. While one device is being replenished with powder / granular material, the other device continues to operate, thereby continuing loss-in-weight control. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Publication No. 60-056236 [Patent Document 2] Patent No. 7089394 Summary of the Invention [Problem to be solved by the invention]

[0007] The technology shown in Patent Document 1 is also called a lock control method because it temporarily stops loss-in-weight control. Although continuous discharge operation is possible, discharge control cannot be performed while powder or granular material is being replenished, so the discharge weight must be varied. If the hopper is made larger to reduce the frequency of this, the amount of powder and granular material stored will also increase, but while there is a large amount of stored powder and granular material, the powder pressure due to the powder and granular material increases and the powder and granular material itself becomes compacted, making it more likely to bridge or get stuck inside the hopper.

[0008] To prevent bridging in the hopper, the powder and granules in the storage section must be stirred, which requires a stirring device called a bridge breaker. This bridge breaker requires a large shaft, stirring blades, and drive unit, which increases the weight of the entire feeder and reduces the measurement accuracy of the weight measuring device used to control the discharge amount of powder and granules. In addition, the bridge breaker causes local density changes in the powder and granules, which is a disturbance to the fixed discharge of the powder and granules.

[0009] Furthermore, since the bulk density of the powder or granules in the hopper varies greatly between when the powder or granules are large and when they are small, the fluctuation in the discharge amount becomes particularly large if discharge amount control is not performed during replenishment. Furthermore, in the technology disclosed in Patent Document 2, when switching between two powder / granular material supplying devices, the discharge amount is actually the sum of the two devices, so it is difficult to keep the discharge amount constant. [Means for solving the problem]

[0010] A powdered or granular material supplying device according to one embodiment of the present invention is a powdered or granular material supplying device comprising a main feeder section having a main hopper for storing powdered or granular material and capable of discharging the powdered or granular material in the main hopper at a predetermined discharge speed, and a sub-feeder section having a sub-hopper for storing powdered or granular material and capable of discharging the powdered or granular material in the sub-hopper to the main hopper at a predetermined discharge speed, wherein the main feeder section is configured to enable loss-in-weight control which references the weight of the main feeder section, and loss-in-weight control which references the total weight of the main feeder section and the sub-feeder section.

[0011] A loss-in-weight control method according to one embodiment of the present invention is a loss-in-weight control method for a powder / granular material supplying device including a main feeder section having a main hopper for accommodating powder / granular material and capable of discharging the powder / granular material in the main hopper at a predetermined discharge speed, and a sub-feeder section having a sub-hopper for accommodating powder / granular material and capable of discharging the powder / granular material in the sub-hopper to the main hopper at a predetermined discharge speed, comprising: measuring the amount of the powder or granular material in the sub-feeder; During a first operation in which the measured amount of the powder or granular material in the sub-feeder unit is greater than a predetermined amount, the main feeder unit is operated under loss-in-weight control that refers to a total weight of the main feeder unit and the sub-feeder unit; After the measured amount of powdered or granular material in the sub-feeder section becomes less than a predetermined amount, during a second operation in which the powdered or granular material is replenished into the sub-feeder section, the main feeder section is operated under loss-in-weight control that references the weight of the main feeder section.

[0012] In the above-described configuration, during the first operation in which the measured amount of powder and granular material in the sub-feeder section is greater than a predetermined amount, the main feeder section is operated under loss-in-weight control that references the total weight of the main feeder section and the sub-feeder section. On the other hand, during the second operation in which the powder and granular material is replenished into the sub-feeder section after the measured amount of the powder and granular material in the sub-feeder section becomes less than a predetermined amount, the main feeder section is operated under loss-in-weight control that references the weight of the main feeder section. This allows operation under loss-in-weight control to continue, including while the powder or granular material is being replenished. Effect of the Invention

[0013] The powder / granular material supplying device of the present invention can continuously perform loss-in-weight control without interruption at all times, including when powder / granular material is being replenished. In other words, it is possible to provide a powder / granular material supplying device that can keep the discharge amount from the main feeder constant. Furthermore, the loss-in-weight control method of the present invention can continue without interruption even when replenishment of powder or granular material is being performed. [Brief description of the drawings]

[0014] [Figure 1] 1 is a partially cutaway front view of a powder / granular material supplying device according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a partially cutaway front view of the powder / granular material supplying device when material is not being replenished. [Diagram 3] FIG. 4 is a partially cutaway front view of the powder / granular material supplying device during material supply. [Figure 4]4 is a diagram showing changes in weight and discharge amount in the powder / granular material supplying device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway front view of a powder / granular material supplying device according to one embodiment of the present invention. In the figure, the main feeder section 1 comprises a main hopper 11 that mainly stores powdered or granular material, a main discharger 12 that discharges the powdered or granular material, a main feeder drive motor 14 that drives the main discharger 12, a main weighing device 13 that measures the overall weight of the main feeder section 1, and a control device 18 that performs overall control. The main discharger 12 is a so-called screw feeder, and is configured to be either a single screw or a twin screw feeder, depending on the characteristics of the powdered or granular material. The main feeder section 1 also includes an A / D converter 16 that converts the analog weight signal output by the main weighing device 13 into a digital signal, and a motor controller 17 that outputs driving power for the main feeder drive motor 14 based on a control signal from the control device 18.

[0016] The main feeder section 1 can perform loss-in-weight control. As the granular material in the main hopper 11 is discharged by the screw feeder of the main discharger 12, the weight of the entire main feeder section 1 measured by the main weigher 13 decreases. When the control device 18 acquires the weighing result of the main weigher 13 via the A / D converter 16, it calculates the reduction amount per hour as the discharge speed of the powder and granular material. The control device 18 can keep the discharge speed constant by controlling the speed of the main feeder drive motor 14 based on a preset discharge speed value. In other words, since the reduction amount per hour is the discharge speed of the powder and granular material, the control device 18 outputs a control signal to the motor controller 17 to drive the main feeder drive motor 14 so as to achieve the preset discharge speed.

[0017] The sub-feeder section 2 mainly comprises a sub-hopper 21 for storing powdered or granular material, a sub-discharger 22 for discharging the powdered or granular material in the sub-hopper 21, a sub-feeder drive motor 24 for driving the sub-discharger 22, a sub-weigher 23 for measuring the weight of the entire sub-feeder section 2, and a control device 28 for overall control. The sub-feeder section 2 also includes an A / D converter 26 that converts the analog weight signal output by the sub-weighing device 23 into a digital signal, and a motor controller 27 that outputs driving power for the sub-feeder driving motor 24 based on a control signal from the control device 28. The sub-discharger 22 is a so-called table feeder. The table lifting cylinder 25 can form or close a gap between the table 22a installed at the bottom of the sub-feeder section 2 and the bottom of the cylindrical sub-hopper 21 based on a control signal from the control device 28. When the sub-feeder drive motor 24 rotates the table 22a with a gap formed, the powder or granular material is discharged from the gap. The control device 28 controls the rotation speed of the table 22a, thereby controlling the discharge amount.

[0018] When discharge from the sub-feeder section 2 is not required, the lifting and lowering of the table is controlled by the table lifting cylinder 25, and the gap between the table 22a and the bottom of the sub-hopper 21 is closed completely, so that no powder or granular material will be discharged thereafter. The control device 28 of the sub-discharger 22 controls the rotation speed of the sub-feeder drive motor 24 by outputting a control signal to the motor controller 27 so that the weight of the main feeder section 1 approaches a preset weight.

[0019] Sub-weigher 23, which measures the weight of sub-feeder section 2, is installed on sub-frame 29, which is a frame independent of the main feeder, so as not to interfere with the weight of main feeder section 1. This allows the weight of main feeder section 1 and the weight of sub-feeder section 2 to be measured without interfering with each other. The weighing result of sub-weigher 23 is output to control device 28 and control device 18 via A / D converter 26.

[0020] This powdered material supplying device has two types of operation modes as shown below. These are a normal operation mode shown in Fig. 2 and a material supply mode shown in Fig. 3. The control device 18 outputs a control signal according to the operation mode to the control device 28, and can control the operation of the entire powdered material supplying device. In the steady operation mode, the sub-feeder unit 2 controls the table lifting cylinder 25 to lower the table 22a of the sub-discharger 22, creating a gap between the table 22a and the lower end of the sub-hopper 21, and then rotates the table 22a with the sub-feeder drive motor 24 to supply powder and granular material through this gap to the main hopper 11. At this time, control is performed to increase or decrease the rotation speed of the table 22a so that the weight of the main feeder unit 1 approaches a preset weight.

[0021] In this steady operation mode, the main discharger 12 performs loss-in-weight control based on the total weight of the main feeder section 1 and the sub-feeder section 2. Specifically, the control device 18 of the main feeder section 1 performs loss-in-weight control based on the weight of the main feeder section 1 measured by the main weigher 13 and the weight of the sub-feeder section 2 measured by the sub-weigher 23, and controls the screw rotation speed of the main feeder drive motor 14 in the main discharger 12 to keep the discharge amount constant.

[0022] If the normal operation mode continues, the powder in the sub-hopper 21 will decrease, and if it continues like this, the sub-hopper 21 will run out of material, so it becomes necessary to replenish the sub-hopper 21 with powder from the outside. At this time, the mode is switched to the material replenishment mode. The mode is switched to the material replenishment mode when an external signal for switching the mode is received, or when the weight of the sub-feeder falls below a preset value. The mode switching signal may be sent, for example, from a timer that determines the time period for switching and forces replenishment when that time period arrives.

[0023] In the material supply mode, first, based on an instruction from the control device 18, the control device 28 stops the driving power of the sub-feeder driving motor 24 to stop the operation of the table 22a in the sub-feeder section 2. Furthermore, the control device 28 controls the table lifting cylinder 25 to lift the table 22a, thereby eliminating the gap between the table 22a and the sub-hopper 21.

[0024] Next, the basis for the loss-in-weight control of the main feeder section 1 is switched from the total weight of the main feeder section 1 and the sub-feeder section 2 to only the weight of the main feeder section 1. Specifically, the control device 18 uses the weight of the main feeder section 1 measured by the main weighing device 13 as the basis, and performs loss-in-weight control while controlling the screw rotation speed of the main feeder drive motor 14 in the main discharger 12 so that the discharge amount is constant. After the control switching is completed, powder or granular material is supplied to the sub-hopper 21 from the outside via the sub-feed port 31.

[0025] Although the weight of the sub-feeder section 2 increases during replenishment, the main feeder section 1 is not affected by the replenishment, and therefore the control device 18 of the main feeder section 1 can continue the loss-in-weight control operation. After the supply of powder to the sub-hopper 21 is completed, the operation mode is switched again from the material supply mode to the normal operation mode. This switching from the material supply mode to the normal operation mode is performed in the following order:

[0026] The control device 18 of the main feeder section 1 switches the basis for loss-in-weight control from only the weight of the main feeder section 1 measured by the main weigher 13 to a total weight including the weight of the sub-feeder section 2 measured by the sub-weigher 23. Based on this change in total weight, the control device 18 performs loss-in-weight control while controlling the screw rotation speed of the main feeder drive motor 14 in the main discharger 12 so that the discharge amount is constant.

[0027] After the reference weight has been changed, the control device 28 controls the table lifting cylinder 25 based on an instruction from the control device 18 to lower the table 22a of the sub-discharger 22 and create a gap between the bottom end of the sub-hopper 21 and the table 22a. Then, the sub-discharger 22 starts to operate, and performs a controlled operation so that the weight of the main feeder section 1 approaches the set weight. At this time, the control device 28 drives the sub-feeder drive motor 24 at a constant speed.

[0028] FIG. 4 shows the changes in weight and discharge amount in a powder / granular material feeder. The graph shows the change over time in G1: weight of main feeder section 1, G2: weight of sub-feeder section 2, G3: total weight of main feeder section 1 and sub-feeder section 2, and G4: discharge amount of main feeder section 1. Let us look at the differences between steady operation when the steady operation mode is in operation and material resupply when the material resupply mode is in operation. During steady operation, the weight of G2: sub-feeder section 2 and the total weight of G3: main feeder section 1 and sub-feeder section 2 gradually decrease, while the weight of G1: main feeder section 1 remains almost constant.

[0029] Next, when material is replenished, the weight of G1: main feeder section 1 gradually decreases, whereas the weight of G2: sub-feeder section 2 and the total weight of G3: main feeder section 1 and sub-feeder section 2 increase. The discharge amount is almost constant both during normal operation and when materials are being replenished. In other words, the powder / granular material supplying device of the present technology can keep the discharge amount constant at all times during operation through loss-in-weight control.

[0030] The main feeder section 1 operates as follows under the control of the control device 18. The weight used as the basis for loss-in-weight control is switched between two types: the weight of the main feeder section 1 only, or the total weight of the main feeder section 1 and the sub-feeder section 2. This is to prevent the loss-in-weight control of the main feeder section 1 from being affected when the amount of powder stored in the sub-hopper 21 becomes low and replenishment is required from outside.

[0031] That is, when the sub-hopper 21 is sufficiently stocked with powder and granular material and the system is in steady operation without external replenishment, the loss-in-weight control of the main feeder section 1 is performed with reference to the total weight of the main feeder section 1 and the sub-feeder section 2. At this time, the sub-feeder section 2 supplies powder and granular material to the main feeder section 1, so the weight of the sub-feeder section 2 continues to decrease. However, the discharge amount of the main feeder section 1 roughly matches the amount supplied from the sub-feeder section 2, so there is almost no change in weight. Specifically, the control device 18 receives the signal output by the main weigher 13 and analog-digital converted by the A / D converter 16, and the signal output by the sub weigher 23 and analog-digital converted by the A / D converter 26, and calculates the total weight value. Then, the control device 18 generates a control signal for making the discharge amount per unit time constant and outputs it to the motor controller 17, thereby controlling the main feeder drive motor 14 that drives the main discharger 12. At this time, the control device 28 generates a control signal for instructing the table 22a to rotate at a constant speed, and outputs it to the motor controller 27. The motor controller 27 generates drive power corresponding to the control signal and outputs it to the sub-feeder drive motor 24.

[0032] Next, when the amount of powder stored in the sub-hopper 21 decreases and replenishment from the outside becomes necessary, it is necessary to switch to the material replenishment mode. When an external signal is received indicating that the powder has decreased, or when the weight of the sub-feeder section 2 falls below a preset weight, the mode automatically switches to the material replenishment mode. To switch to the material supply mode, the control device 28 outputs a control signal to the motor controller 27 to stop the sub-feeder drive motor 24. This stops the supply of powder and granular material from the sub-feeder unit 2 to the main feeder unit 1. At this time, the control device 28 instructs the table lifting cylinder 25 to lift the table 22a and close the gap between the bottom end of the sub-hopper 21 and the table 22a. Next, the reference weight value for the loss-in-weight control of main feeder section 1 is switched from the total weight of main feeder section 1 and sub-feeder section 2 to the weight of main feeder section 1 only. Specifically, the control device 18 inputs the signal output by the main weighing device 13 and converted from analog to digital by the A / D converter 16, generates a control signal to keep the discharge amount per unit time constant, and outputs the control signal to the motor controller 17, thereby controlling the main feeder drive motor 14 that drives the main discharger 12. After the control is switched, the sub-hopper 21 is replenished with powder from outside.

[0033] When replenishment is completed and the machine returns to normal operation mode, this is done automatically when an external signal is received indicating that the amount of powder or granular material has increased, or when the weight of the sub-feeder section 2 exceeds a preset weight value. To switch from the material supply mode to the normal operation mode, first the weight value that serves as the reference for the loss-in-weight control of the main feeder section 1 is changed from the weight of the main feeder section 1 alone to the total weight of the main feeder section 1 and the sub-feeder section 2. After that, the supply of powder and granular material from the sub-feeder section 2 to the main feeder section 1 is resumed. The control device 28 instructs the table lifting cylinder 25 to lower the table 22a and open a gap between the bottom end of the sub-hopper 21 and the table 22a, and the control device 28 generates a control signal to rotate the table 22a at a constant speed and outputs it to the motor controller 27, so that the sub-feeder drive motor 24 rotates at a low speed.

[0034] [Aspect 1] In this way, the powdered or granular material supplying device comprises a main feeder section 1 having a main hopper 11 that stores powdered or granular material and capable of discharging the powdered or granular material in the main hopper 11 at a predetermined discharge speed, and a sub-feeder section 2 having a sub-hopper 21 that stores powdered or granular material and capable of discharging the powdered or granular material in the sub-hopper 21 to the main hopper 11 at a predetermined discharge speed, and the main feeder section 1 is capable of loss-in-weight control that references the weight of the main feeder section 1 (measured by a main weighing device 13) and loss-in-weight control that references the total weight of the main feeder section 1 and the sub-feeder section 2 (measured by a main weighing device 13 and a sub-weighing device 23).

[0035] The loss-in-weight control method implemented by this powdered or granular material supplying device includes a step of measuring the amount of powdered or granular material in the sub-feeder section 2, and a step of operating the main feeder section 1 under loss-in-weight control which references the total weight of the main feeder section 1 and the sub-feeder section 2 during a first operation (steady operation mode) in which the measured amount of powdered or granular material in the sub-feeder section 2 is greater than a predetermined amount, and a step of operating the main feeder section 1 under loss-in-weight control which references the weight of the main feeder section 1 during a second operation (material replenishment mode) in which powdered or granular material is replenished into the sub-feeder section 2 after the measured amount of powdered or granular material in the sub-feeder section 2 becomes less than the predetermined amount.

[0036] [Aspect 2] The main feeder section 1 has a main feeder (main discharger 12) whose discharge speed can be controlled, and the loss-in-weight control of the main feeder section 1 controls the discharge speed of the main feeder (main discharger 12) by increasing or decreasing the discharge speed so that the reference weight reduction weight speed approaches a preset discharge weight speed. [Aspect 3] When an external signal is input to the main feeder unit 1, or when the weight of the sub-feeder unit 2 becomes smaller than a preset weight, the main feeder unit 1 stops supplying from the sub-feeder unit 2 to the main feeder unit 1, and the main feeder unit 1 switches from loss-in-weight control, which refers to the total weight of the main feeder unit 1 and the sub-feeder unit 2, to loss-in-weight control, which refers to the weight of the main feeder unit 1 only.

[0037] [Aspect 4] The sub-feeder section 2 has a sub-feeder (sub-discharger 22) whose discharge speed can be controlled, and controls the discharge speed of the sub-feeder (sub-discharger 22) by increasing or decreasing it so that the weight of the main feeder section 1 approaches a preset weight. That is, the supply amount of the sub-feeder (sub-discharger 22) is controlled so as to approach the set weight value of the main feeder section 1. During steady operation, the main feeder section 1 is operated at a constant discharge amount by loss-in-weight control, but since it is supplied from the sub-feeder section 2, the weight of the main feeder section 1 is stable, and therefore the amount of powder and granular material stored in the main hopper 11 is also maintained at an almost constant amount.

[0038] [Aspect 5] The main feeder (main discharger 12) is a screw feeder. By rotating the screw, the powder loaded between the flights moves forward and is discharged from the front discharge port. Since the discharge amount of the powder increases or decreases depending on the rotation speed of the screw, the rotation speed of the main feeder drive motor 14 is controlled by loss-in-weight control to adjust the discharge amount.

[0039] [Aspect 6] The sub-feeder (sub-discharger 22) is a table feeder in which the bottom surface of the sub-hopper 21 has a rotating table 22a. There is a gap between the bottom end of the sub-hopper 21 and the table 22a of the sub-discharger 22, and as the table 22a rotates, the powder or granular material falls from this gap and is supplied to the main hopper 11. Since the discharge amount of the powder or granular material can be increased or decreased by changing the rotation speed of the table 22a, the number of rotations of the table is controlled so as to approach the target weight value of the main feeder section 1.

[0040] It goes without saying that the present invention is not limited to the above-mentioned embodiment. -Appropriately change and apply the mutually replaceable members and configurations disclosed in the above embodiments. · Appropriately replacing members and configurations that are not disclosed in the above embodiments but are publicly known and can be mutually substituted for the members and configurations disclosed in the above embodiments, and changing the combinations thereof for application. - Substitute members and configurations, etc. that are not disclosed in the above embodiments but that a person skilled in the art could imagine as substitutes for the members and configurations, etc. disclosed in the above embodiments based on publicly known techniques, and change and apply the combinations. is disclosed as one embodiment of the present invention. Specifically, various modifications are possible. For example, the sub-feeder section 2 can be placed on the main feeder section 1, the weight of the main feeder section 1 can be measured as the sum of the weight of the main feeder section 1 and the sub-feeder section 2, and the weight of the sub-feeder section 2 can be measured using a sub-weighing device 23 installed on the sub-feeder section 2 placed on the main feeder section 1, and the weight of only the main feeder section 1 can be calculated by subtracting the weight value of the sub-weighing device 23 from the weight value of the main weighing device 13.

[0041] As another modification, the sub-feeder section 2 can be changed from the table feeder type to the screw feeder type. As yet another modified example, the main feeder section 1 can be changed from the screw feeder type to a table feeder type. [Explanation of symbols]

[0042] 1...main feeder section, 11...main hopper, 12...main discharger, 13...main weighing device, 14...main feeder drive motor, 16...A / D converter, 17...motor controller, 18...control device, 2...sub feeder section, 21...sub hopper, 22...sub discharger, 22a...table, 23...sub weighing device, 24...sub feeder drive motor, 25...table lifting cylinder, 26...A / D converter, 27...motor controller, 28...control device, 29...sub stand, 31...sub inlet.

Claims

1. a main feeder section having a main hopper for accommodating powder or granular material and capable of discharging the powder or granular material in the main hopper at a predetermined discharge speed; A powdered or granular material supplying device having a sub-hopper for accommodating powdered or granular material, and a sub-feeder unit capable of discharging the powdered or granular material in the sub-hopper to the main hopper at a predetermined discharge speed, A powdered or granular material supplying device characterized in that the main feeder section is capable of loss-in-weight control that references the weight of the main feeder section and loss-in-weight control that references the total weight of the main feeder section and the sub-feeder section.

2. 2. The powder / granular material supplying device according to claim 1, wherein the main feeder unit has a main feeder capable of controlling a discharge speed, and the loss-in-weight control of the main feeder is performed by increasing or decreasing the discharge speed of the main feeder so that a weight loss speed serving as a reference approaches a preset discharge weight speed.

3. 3. The powdered or granular material supplying device according to claim 1, wherein the main feeder unit stops supplying from the sub-feeder unit to the main feeder unit when an external signal is input or when the weight of the sub-feeder unit becomes smaller than a preset weight, and the main feeder unit switches from loss-in-weight control, which refers to a total weight of the main feeder unit and the sub-feeder unit, to loss-in-weight control, which refers to a weight of only the main feeder unit.

4. The powdered or granular material supplying device according to claim 1, characterized in that the sub-feeder section has a sub-feeder whose discharge speed can be controlled, and the discharge speed of the sub-feeder is increased or decreased so that the weight of the main feeder section approaches a preset weight.

5. 3. The powder / granular material supplying device according to claim 2, wherein the main feeder is a screw feeder.

6. 5. The powdered material supplying device according to claim 4, wherein the sub-feeder is a table feeder in which the bottom surface of the sub-hopper rotates.

7. A loss-in-weight control method for a powdered or granular material supplying device including a main feeder section having a main hopper for accommodating powdered or granular material and capable of discharging the powdered or granular material in the main hopper at a predetermined discharge speed, and a sub-feeder section having a sub-hopper for accommodating powdered or granular material and capable of discharging the powdered or granular material in the sub-hopper to the main hopper at a predetermined discharge speed, comprising: measuring the amount of the powder or granular material in the sub-feeder; During a first operation in which the measured amount of the powder or granular material in the sub-feeder unit is greater than a predetermined amount, the main feeder unit is operated under loss-in-weight control that refers to a total weight of the main feeder unit and the sub-feeder unit; and during a second operation in which the powder or granular material is replenished into the sub-feeder section after the measured amount of the powder or granular material in the sub-feeder section becomes less than a predetermined amount, the main feeder section is operated under loss-in-weight control that references the weight of the main feeder section.

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