Powder online calibration metering device

Abstract

The utility model provides a powder on-line calibration metering device which comprises a calibration stock bin, a spiral conveyor, a rotating speed sensor and a controller. The calibration stock bin is suspended below the powder supply device through a plurality of first suspenders to receive powder, each first suspender is provided with a first weighing sensor, and the bottom of the calibration stock bin is provided with a blanking port; the screw conveyor is suspended below the calibration stock bin through a plurality of second suspenders, each second suspender is provided with a second weighing sensor, the two ends of the screw conveyor are provided with a feeding port and a discharging port respectively, the feeding port is used for receiving powder falling from the discharging port, and the discharging port is provided with a discharging valve; the rotating speed sensor is arranged on the screw conveyor to detect the rotating speed of the screw conveyor; the controller is electrically connected with the first weighing sensor, the second weighing sensor, the rotating speed sensor and the spiral conveyor. The powder on-line calibration metering device provided by the utility model can improve metering efficiency and accuracy.

Description

Technical Field

[0001] This utility model belongs to the field of powder metering technology, specifically relating to an online calibration and metering device for powder. Background Technology

[0002] The original recycled asphalt mixture is composed of four components: virgin aggregate, recycled aggregate, powder, and asphalt, mixed in a predetermined ratio. Among them, virgin aggregate and recycled aggregate are both granular aggregates, which are usually added quantitatively by volumetric metering and weighing. The viscous asphalt requires a special asphalt scale for quantitative metering. The powder is metered differently from aggregate and asphalt, and is usually added quantitatively by screw weighing during the conveying process.

[0003] Existing screw metering scales typically determine powder flow rate based on the screw's volume and rotational speed. However, during startup, the screw metering scale requires filling the screw with powder and stabilizing the flow rate before quantitatively feeding powder into the mixing system. This results in a large amount of powder needing to be discharged and recovered during the initial startup phase, which is time-consuming and labor-intensive. Furthermore, during normal metering and conveying, variations in the powder flow rate can cause metering errors, affecting the accuracy of powder addition. Utility Model Content

[0004] This utility model provides an online calibration and metering device for powder materials, which aims to improve metering efficiency and accuracy.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: to provide an online calibration and metering device for powder, comprising:

[0006] The calibration hopper is suspended below the powder supply device by multiple first lifting rods to receive powder. Each first lifting rod is equipped with a first weighing sensor, and the bottom of the calibration hopper is equipped with a discharge port.

[0007] The screw conveyor is suspended below the calibration hopper by multiple second rods. Each second rod is equipped with a second weighing sensor. The screw conveyor has an inlet and an outlet at both ends. The inlet is used to catch the powder falling from the outlet, and the outlet is equipped with a discharge valve.

[0008] A speed sensor is installed on the screw conveyor to detect the speed of the screw conveyor;

[0009] The controller is electrically connected to each of the first weighing sensors, each of the second weighing sensors, and the speed sensor, and is also electrically connected to the screw conveyor.

[0010] In a possible implementation, the powder online calibration metering device further comprises a screw discharging machine, a feeding end of the screw discharging machine is located directly below the discharging opening to receive the powder from the calibration bin, and a discharging end of the screw discharging machine is located directly above the feeding opening to discharge the powder to the feeding opening; the screw discharging machine is electrically connected with the controller.

[0011] In some embodiments, the feeding end of the screw discharging machine is connected with the discharging opening through a first corrugated hose, and the discharging end of the screw discharging machine is connected with the feeding opening through a second corrugated hose.

[0012] For example, the screw discharging machine is arranged in an inclined manner, and the feeding end of the screw discharging machine is lower than the discharging end.

[0013] For example, the power source of the screw discharging machine is a first variable frequency motor controlled by the controller; wherein the controller adjusts the rotating speed of the first variable frequency motor based on the descending speed of the detection value of the first weighing sensor.

[0014] In a possible implementation, the power source of the screw discharging machine is a second variable frequency motor controlled by the controller; wherein when the descending speed of the detection value of the first weighing sensor is in a set speed range, the controller adjusts the rotating speed of the second variable frequency motor based on the detection value of the second weighing sensor.

[0015] In some embodiments, two second hangers are distributed along the axial direction of the screw discharging machine, and the two second hangers are symmetrically distributed on two sides of the gravity center of the screw discharging machine in the empty state.

[0016] For example, the discharging valve is an electric valve controlled by the controller; wherein the controller controls the opening and closing of the electric valve based on the detection value of the second weighing sensor.

[0017] The powder online calibration metering device has the following advantages: compared with the prior art, the powder online calibration metering device can continuously feed the screw discharging machine below the calibration bin, the discharging opening is closed by the discharging valve before starting, the screw discharging machine starts to operate and makes the powder falling into the feeding opening completely fill the conveying screw, at this time, the detection value of the second weighing sensor enters the target range, then the discharging valve is opened to start discharging the discharging opening, thereby the powder emptying and recycling step before the screw discharging machine obtains a stable conveying flow can be omitted, and the starting preparation time is reduced to improve the efficiency.

[0018] The weight of the calibration bin is detected in real time through the first weighing sensor during the discharging process, the powder discharging flow of the calibration bin is obtained according to the descending rate of the detection value of the first weighing sensor, the rotating speed sensor can detect the rotating speed of the screw conveyor in real time, and then the powder discharging flow of the screw conveyor is obtained through the rotating speed, and then the powder discharging flow of the screw conveyor is calibrated and controlled by using the powder discharging flow of the calibration bin, so that the accuracy of powder conveying and metering is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A structural schematic diagram of the powder online calibration metering device is provided for the embodiments of the present application.

[0020] Figure 2 A circuit block diagram of the powder online calibration metering device is provided for the embodiments of the present application.

[0021] Figure 3 A control strategy block diagram of the powder online calibration metering device is provided for the embodiments of the present application.

[0022] In the figure: 10, calibration bin; 11, first boom; 12, first weighing sensor; 13, discharging port; 20, screw conveyor; 21, second boom; 22, second weighing sensor; 23, feeding port; 24, discharging port; 25, discharging valve; 26, second variable frequency motor; 30, rotating speed sensor; 40, screw discharging machine; 41, first corrugated hose; 42, second corrugated hose; 43, first variable frequency motor. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0024] It should be noted that when an element is referred to as being "disposed on" or "connected to" another element, it can be directly on or indirectly on the other element. It should be understood that the terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or several features. In the description of the present application, the meaning of "a plurality of", "several" is two or more than two, unless otherwise specifically limited.

[0025] Please refer to Figures 1 to 3The powder online calibration metering device comprises a calibration bin 10, a screw conveyor 20, a rotating speed sensor 30 and a controller, wherein the calibration bin 10 is suspended below a powder supply device through a plurality of first hangers 11 to receive powder, each first hanger 11 is provided with a first weighing sensor 12, and the bottom of the calibration bin 10 is provided with a discharging port 13; the screw conveyor 20 is suspended below the calibration bin 10 through a plurality of second hangers 21, each second hanger 21 is provided with a second weighing sensor 22, and the two ends of the screw conveyor 20 are respectively provided with an inlet port 23 and an outlet port 24, the inlet port 23 is used for receiving the powder falling from the discharging port 13, and the outlet port 24 is provided with a discharging valve 25; the rotating speed sensor 30 is arranged on the screw conveyor 20 to detect the rotating speed of the screw conveyor 20; and the controller is respectively electrically connected with each first weighing sensor 12, each second weighing sensor 22 and the rotating speed sensor 30, and is electrically connected with the screw conveyor 20.

[0026] It should be explained that the calibration bin 10 is suspended below the powder supply device to receive powder, and the powder supply device as a component capable of continuously filling the calibration bin 10 can be a large-capacity powder storage bin which discharges powder into the calibration bin 10 through a powder outlet below the powder storage bin, or can be a powder conveyor which feeds the powder in the powder storage bin into the calibration bin 10; it should be emphasized that the powder supply device feeds the calibration bin 10 intermittently, and therefore the powder supply device should have a discharging switch structure such as a valve.

[0027] On the basis of the above, in consideration of the continuity and uniformity of the feeding of the calibration bin 10 to the screw conveyor 20, the calibration bin 10 should not be emptied, and therefore the calibration bin 10 should be provided with a minimum material level, which can be a weight conversion material level, when the weight represented by the detection value of the first weighing sensor 12 is lower than the weight corresponding to the minimum material level, the powder supply device starts to add powder into the calibration bin 10, and similarly, in order to realize the calibration of the powder, the calibration bin 10 also needs to be provided with a maximum material level, which is also a weight conversion material level, when the weight represented by the detection value of the first weighing sensor 12 matches the weight corresponding to the maximum material level, the powder supply device stops filling the calibration bin 10; thus, the detection of the overall weight of the calibration bin 10 by the first weighing sensor 12 can be used as a basis for controlling the amount of each feeding of the calibration bin 10, thereby realizing the quantitative calibration effect of the powder in the calibration bin 10.

[0028] It should be noted that the calibration silo 10 can be a plurality of first hangers 11 distributed along its circumference, and the force of each first hanger 11 is balanced, so the total weight of the calibration silo 10 and the sum of the detection values of each first weighing sensor 12, in the description of the present application, the detection value of the first weighing sensor 12 is the sum of the detection values of each first weighing sensor 12, unless otherwise specified.

[0029] Similarly, each second hanger 21 for suspending the screw conveyor 20 in the present embodiment should also be balanced in force, so that the total weight of the screw conveyor 20 can be represented by the sum of the detection values of each second weighing sensor 22, in the description of the present application, the detection value of the second weighing sensor 22 represents the sum of the detection values of each first weighing sensor 12, unless otherwise specified.

[0030] The screw conveyor 20 is a conveying device that uses the rotation of the conveying cylinder with a screw conveying shaft to push the powder to move, and its conveying principle is prior art, which will not be described in detail here. In the present embodiment, by determining the pitch of the helical blade of the screw conveying shaft, and then matching the rotating speed of the rotating conveying shaft, the speed of the screw conveying shaft pushing the powder can be obtained, and on this basis, the powder flow in the screw conveyor 20 can be obtained by multiplying the powder movement speed by the cross-sectional area of the screw conveyor 20 that can effectively accommodate the powder.

[0031] Theoretically, when the powder fills the internal space of the screw conveyor 20 and keeps constant speed running, the powder flow is fixed, but considering the actual situation, there may be powder cavities in the screw conveyor 20, so the actual powder flow fluctuates, and if the flow fluctuation is too large, intervention is needed, and at this time the function of the second weighing sensor 22 is to obtain whether the powder filling in the screw conveyor 20 is dense through the change of the detection value of the second weighing sensor 22, so that the powder flow fluctuation can be found in time, thereby avoiding the problem of inaccurate powder measurement.

[0032] In addition, under normal operating conditions, the powder flow into the screw conveyor 20 from the calibration silo 10 should be consistent with the powder flow out of the screw conveyor 20, and the powder flow into the screw conveyor 20 can be determined by the detection value of the first weighing sensor 12 in the unit time, that is, the detection value drop rate, and the discharge amount is converted from the detection value of the speed sensor 30. Since the feeding speed determined by the detection value drop rate does not have too many interference factors, it can be considered to be accurate, and the powder flow out of the screw conveyor 20 has many interference factors, so the data obtained by the speed conversion may have large errors, so the powder flow into the screw conveyor 20 can be used to calibrate the data of the powder flow out of the screw conveyor 20, thereby improving the measurement accuracy.

[0033] Of course, in addition to the interference factors of the screw conveyor 20 itself, if the powder feeding flow of the screw conveyor 20 cannot match the powder discharging flow, it may be due to the fact that the rotation speed of the screw conveyor 20 does not match, but under normal circumstances, since the powder addition amount is determined, it is not convenient to adjust the rotation speed of the screw conveyor 20, so at this time the controller needs to regulate the powder feeding flow, so as to avoid the powder in the screw conveyor 20 from being blocked due to the large powder feeding flow, or the actual powder discharging flow being lower than the requirement due to the small powder feeding flow, thereby affecting the accuracy of the powder addition amount.

[0034] Compared with the prior art, the powder online calibration metering device provided by the embodiment can continuously feed the powder in the calibration bin 10 to the screw conveyor 20 below, and the discharge valve 25 is closed before starting to make the powder falling into the feeding port 23 of the screw conveyor 20 completely fill the conveying screw of the screw conveyor 20, at this time, the detection value of the second weighing sensor 22 enters the target interval, and then the discharge valve 25 is opened to make the discharge port 24 start discharging, thereby the powder emptying and recycling step before the screw conveyor 20 obtains a stable conveying flow can be omitted, thereby reducing the starting preparation time and improving the efficiency.

[0035] In the discharging process, the weight of the calibration bin 10 is detected in real time by the first weighing sensor 12, the powder discharging flow of the calibration bin 10 is obtained according to the falling rate of the detection value of the first weighing sensor 12, the rotation speed of the screw conveyor 20 is detected in real time by the rotation speed sensor 30, and then the powder discharging flow of the screw conveyor 20 is obtained through the rotation speed, and then the powder discharging flow of the screw conveyor 20 is calibrated and regulated by using the powder discharging flow of the calibration bin 10, thereby improving the accuracy of powder conveying and metering.

[0036] As a variant embodiment of the above-mentioned powder online calibration metering device, please refer to Figure 1 The powder online calibration metering device in the embodiment further comprises a screw discharging machine 40, the feeding end of the screw discharging machine 40 is located directly below the feeding port 13 to receive the powder of the calibration bin 10, the discharging end of the screw discharging machine 40 is located directly above the feeding port 23 to discharge the powder to the feeding port 23, and the screw discharging machine 40 is electrically connected with the controller.

[0037] It is known from the above embodiment that the continuity, stability and controllability of the powder feeding of the screw conveyor 20 are very important, and the direct feeding mode of the calibration bin 10 to the screw conveyor 20 is difficult to meet these requirements, so the screw discharging machine 40 is used to continuously transfer the powder of the calibration bin 10 to the screw conveyor 20, and the rotation speed of the screw discharging machine 40 can be regulated by the controller, thereby controlling the feeding speed of the screw conveyor 20, so as to improve the stability and uniformity of the powder feeding flow of the screw conveyor 20.

[0038] It should be noted that, in order to avoid the screw conveyor 40 affecting the weighing accuracy of the calibrated hopper 10 and screw conveyor 20, such as... Figure 1 As shown, in this embodiment, the feed end of the screw conveyor 40 is connected to the discharge port 13 via a first corrugated hose 41, and the discharge end of the screw conveyor 40 is connected to the feed port 23 via a second corrugated hose 42. Using corrugated hoses for connection avoids affecting the weighing accuracy of the calibrated hopper and screw conveyor 20 at the connection points, and also prevents powder leakage.

[0039] Specifically, please refer to Figure 1 In this embodiment, the screw conveyor 40 is inclined vertically, and the feed end of the screw conveyor 40 is lower than its discharge end. The inclined arrangement of the screw conveyor 40 helps to reduce the installation height of the calibration hopper and allows the powder entering the screw conveyor 40 to fill its cross-sectional space, enabling the powder to densely fill the screw conveyor blades and improve the uniformity of discharge. This, in turn, achieves continuous and uniform feeding of the screw conveyor 20, thereby improving the metering accuracy of the powder by the screw conveyor 20.

[0040] Among the possible implementation methods, please combine... Figures 1 to 3 Understood, the power source of the spiral conveyor 40 is the first variable frequency motor 43 controlled by the controller; wherein, the controller adjusts the speed of the first variable frequency motor 43 based on the rate of decrease of the detected value of the first weighing sensor 12.

[0041] As powder continuously enters the screw conveyor 40 from the calibration hopper, its weight decreases accordingly. The ratio of the weight decrease to time is the rate of decrease of the detected value of the first weighing sensor 12. This determines the powder discharge flow rate of the calibration hopper and also the flow rate of powder entering the screw conveyor 20. The powder flow rate of the screw conveyor 20 should be constant. Therefore, the powder discharge flow rate of the calibration hopper should be maintained within the corresponding set range. If the rate of decrease of the detected value is higher than the set range, it means that the discharge is too fast. The controller should control the first variable frequency motor 43 to reduce its speed, thereby reducing the powder discharge flow rate of the calibration hopper. Conversely, the controller should control the first variable frequency motor 43 to increase its speed, thereby increasing the powder discharge flow rate of the calibration hopper. This ensures a stable powder discharge flow rate, helps improve the continuous uniformity of powder entering the screw conveyor 20, and improves the accuracy of powder metering.

[0042] Optionally, in this embodiment, the power source of the screw conveyor 20 is a second variable frequency motor 26 controlled by a controller; wherein, when the rate of decrease of the detected value of the first weighing sensor 12 is within the set rate range, the controller adjusts the speed of the second variable frequency motor 26 based on the detected value of the second weighing sensor 22.

[0043] When the detection value of the first weighing sensor 12 keeps at the set rate interval, it indicates that the calibration hopper 10 is in a state of stable powder output according to the set flow rate, and under normal circumstances, the screw conveyor 20 should keep the current weight unchanged, so as to realize the matching of the powder output flow rate of the screw conveyor 20 and the air inlet flow rate. If the detection value of the second weighing sensor 22 is higher than the target interval, it indicates that the powder output speed of the screw conveyor 20 is low, so the controller controls the second variable frequency motor 26 to increase the rotating speed, so as to increase the powder output flow rate of the screw conveyor 20. Conversely, the controller controls the second variable frequency motor 26 to reduce the rotating speed to reduce the powder output flow rate of the screw conveyor 20. Thus, the rotating speed of the screw conveyor 20 can be dynamically regulated, so as to improve the matching degree of the powder output flow rate of the screw conveyor 20 and the powder output flow rate of the calibration hopper, and further improve the powder metering accuracy.

[0044] As shown in Figure 1 the second hanger rods 21 are spaced apart along the axial direction of the screw conveyor 20, and the two hanger rods are symmetrically distributed on the two sides of the gravity center of the screw conveyor 20 in the empty state. The two second hanger rods 21 are symmetrically distributed based on the gravity center of the screw conveyor 20, so that on the one hand, the total weight of the screw conveyor 20 can be obtained by the sum of the detection values of the two, and on the other hand, when the detection values of the two exceed the tolerance, it can be judged that the distribution of the powder in the screw conveyor 20 is not uniform enough, so that the controller can issue an alarm to notify the operator to intervene in time, and further ensure the accuracy of the powder metering.

[0045] In some possible implementation manners, it can be understood that Figures 1 to 3 the discharge valve 25 is an electric valve controlled by the controller, and the controller controls the opening and closing of the electric valve based on the detection value of the second weighing sensor 22. The use of the electric valve can avoid the disadvantage that manual operation cannot be timely, and improve the timeliness of the action of the discharge valve 25. On this basis, the opening and closing of the electric valve is mainly used in the initial stage of the operation, and under normal circumstances, the discharge valve 25 is in a closed state. When the machine is running, the powder continuously enters the screw conveyor 20, and when the powder reaches the discharge port 24, the powder gradually fills the internal space of the screw conveyor 20 due to the inability to discharge. When the detection value of the second weighing sensor 22 reaches the target interval (the detection value corresponds to the total weight of the screw conveyor 20 when it is filled with powder), the discharge valve 25 can be automatically opened by the controller. Thus, not only can the step of emptying and recycling the powder of the screw conveyor 20 in the initial stage be omitted, thereby improving the online metering efficiency in the powder conveying process, but also the internal space of the screw conveyor 20 can be filled with powder, thereby improving the accuracy of judging the powder output flow rate based on the detection value of the rotating speed sensor 30.

[0046] Based on the above, in combination with Figures 1 to 3It is understood that the control strategy of the powder online calibration metering device provided by the embodiment is as follows:

[0047] In the starting stage, the electric valve is in the closed state, the second weighing sensor 22 detects the weight of the calibration hopper, and when the detection value of the second weighing sensor 22 reaches the target interval, the electric valve is opened to start feeding into the spiral discharger 40. At this time, the metering calibration stage is entered.

[0048] During calibration, the set rate interval of the first weighing sensor 12 is first determined according to the amount of powder required to be added to the mixed material. When the falling rate of the detection value of the first weighing sensor 12 is higher than the set rate interval, the controller reduces the rotating speed of the first variable frequency motor 43, and vice versa. The falling rate of the detection value is kept in the set rate interval, so that the powder flow rate of the calibration hopper is guaranteed to meet the requirements of the powder flow rate of the spiral conveyor 20.

[0049] After the powder flow rate of the spiral conveyor 20 is calibrated by the second weighing sensor 22, the powder flow rate of the spiral conveyor 20 is calibrated by the falling rate of the detection value of the first weighing sensor 12. When the detection value of the second weighing sensor 22 cannot be kept in the target interval, it indicates that the powder flow rate does not match the air flow rate. If the detection value is higher than the target interval, the controller controls the second variable frequency motor 26 to increase the rotating speed, and vice versa. The powder flow rate of the spiral conveyor 20 is dynamically adjusted by adjusting the rotating speed of the second variable frequency motor 26, so that the powder flow rate matches the air flow rate. At this time, the detection value of the second weighing sensor 22 is kept in the target interval.

[0050] Finally, the powder flow rate of the spiral conveyor 20 corresponding to the detection value of the rotating speed sensor 30 is calibrated by the powder flow rate of the calibration hopper corresponding to the falling rate of the detection value of the first weighing sensor 12. After calibration, the powder flow rate of the spiral conveyor 20 can be directly judged by the detection value of the rotating speed sensor 30, so as to guarantee the accuracy of the spiral metering scale for online metering of powder.

[0051] After the above calibration process is completed, the current running state is kept to guarantee the online calibration metering during powder conveying. At the same time, the rotating speeds of the first variable frequency motor 43 and the second variable frequency motor 26 are real-time adjusted during running, and the corresponding value between the rotating speed of the spiral conveyor 20 and the discharging speed is real-time calibrated, so as to improve the accuracy of the powder online calibration metering.

[0052] The above only describes the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An on-line calibration metering device for powders, characterized in that, The application relates to a powder online calibration metering device. The calibration bin is suspended below the powder supply device by a plurality of first hangers, each of which is provided with a first weighing sensor, and the bottom of the calibration bin is provided with a discharging port; The screw conveyor is suspended below the calibration bin by a plurality of second hangers, each of which is provided with a second weighing sensor, and the screw conveyor is provided with a feeding port and a discharging port at two ends, the feeding port is used for receiving the powder falling from the discharging port, and the discharging port is provided with a discharging valve; A rotational speed sensor is arranged on the screw conveyor to detect the rotational speed of the screw conveyor; A controller is electrically connected with each of the first weighing sensors, each of the second weighing sensors and the rotational speed sensor, and is electrically connected with the screw conveyor.

2. The on-line calibration metering device for powder as claimed in claim 1, wherein, The powder online calibration metering device further comprises a screw discharging machine, the feeding end of the screw discharging machine is located directly below the discharging port to receive the powder of the calibration bin, the discharging end of the screw discharging machine is located directly above the feeding port to discharge the powder to the feeding port, and the screw discharging machine is electrically connected with the controller.

3. The on-line calibration metering device for powder as claimed in claim 2, wherein, The feeding end of the screw discharging machine is connected with the discharging port through a first corrugated hose, and the discharging end of the screw discharging machine is connected with the feeding port through a second corrugated hose.

4. The on-line calibration metering device for powder as claimed in claim 2, wherein, The screw discharging machine is arranged in an up-down inclined mode, and the feeding end of the screw discharging machine is lower than the discharging end.

5. The on-line calibration metering device for powder as claimed in claim 2, wherein, The power source of the screw discharging machine is a first variable frequency motor controlled by the controller; wherein the controller adjusts the rotational speed of the first variable frequency motor based on the descending rate of the detection value of the first weighing sensor.

6. The on-line calibration metering device for powder as claimed in claim 5, wherein, The power source of the screw conveyor is a second variable frequency motor controlled by the controller; wherein when the descending rate of the detection value of the first weighing sensor is in a set rate range, the controller adjusts the rotational speed of the second variable frequency motor based on the detection value of the second weighing sensor.

7. An on-line calibration metering device for powder as claimed in any one of claims 1 to 6, wherein, The second hangers are spaced apart along the axial direction of the screw conveyor, and two of the hangers are symmetrically arranged on the two sides of the gravity center of the screw conveyor in an empty state.

8. The on-line calibration metering device for powder as claimed in claim 5, wherein, The discharging valve is an electric valve controlled by the controller; wherein the controller controls the opening and closing of the electric valve based on the detection value of the second weighing sensor.

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