Methods to improve the weighing accuracy of vertical spiral bagging devices

Abstract

A method for improving the weighing accuracy of an intelligent vertical spiral bagging device is disclosed. The intelligent vertical spiral bagging device includes a lifting column, with a lifting motor at its upper end and a rotary encoder. The lifting motor drives a weighing and bagging mechanism to move up and down along a guide rail on the lifting column. The weighing sensor signal of the weighing and bagging mechanism is transmitted to a weighing instrument, which transmits the weighing weight signal to a PLC control system. The weighing instrument can also receive weight data returned by the PLC control system. The PLC control system is responsible for coordinating and controlling all actions of the entire vertical spiral bagging device. The method for improving the weighing accuracy of the intelligent vertical spiral bagging device includes: pre-determining the tare weight value within the upper and lower intervals of the initial flow position; dynamically determining the flow position for each weighing and bagging operation, querying and calculating the tare weight value at the current flow position, and dynamically adjusting the flow threshold. This invention can eliminate weighing errors caused by changes in material density and tare weight variations at different flow positions.

Description

Technical Field

[0001] This invention discloses a method for improving the weighing accuracy of a vertical spiral bagging device, belonging to the field of powder packaging machinery. Background Technology

[0002] Patent document CN111846305B discloses an intelligent vertical spiral bagging device that maintains a constant distance between the spiral outlet and the material surface inside the bag during the coarse flow feeding stage. After the coarse flow ends, the bagging mechanism descends to a fixed fine flow position and continues fine flow feeding until weighing is completed. Due to the variation in the bulk density of powder materials, the total volume of material inside the bag, i.e., the material surface height, is constantly changing at the end of the coarse flow. When the bagging mechanism descends to the fixed fine flow position, the distance between the spiral outlet and the material surface inside the bag is also constantly changing, causing instability in the weight of the material flying in the air before the end of the fine flow, resulting in a large weighing error. Currently, the weighing error is generally ±0.2% to ±0.35%, which is lower than the ±0.1% weighing error for granular materials, indicating a need to further improve the weighing accuracy of the vertical spiral bagging device. Summary of the Invention

[0003] To address the problem of unstable weight of airborne material during the fine flow stage in existing vertical spiral bagging devices, resulting in low weighing accuracy, this invention proposes a method to improve the weighing accuracy of vertical spiral bagging devices. The vertical spiral bagging device includes a lifting column 1, with a lifting motor 2 at the upper end of the lifting column 1. The lifting motor 2 is equipped with a rotary encoder. The lifting motor 2 drives a weighing and bagging mechanism 3 to move up and down along the guide rail on the lifting column 1. The weighing sensor signal of the weighing and bagging mechanism 3 is transmitted to a weighing instrument 4. The weighing instrument 4 transmits the weighing weight signal to a PLC control system 5. The weighing instrument 4 receives the weight data returned by the PLC control system 5. The PLC control system 5 is responsible for coordinating and controlling all actions of the entire vertical spiral bagging device.

[0004] The method for improving the weighing accuracy of the vertical spiral bagging device includes the following steps:

[0005] S0: Set the initial position of the flow to the origin Y(0) of the Y-axis, set the high position of the flow a distance above the origin Y(0) to Y(A), and set the low position of the flow a distance below the origin Y(0) to Y(-B);

[0006] S1: The lifting motor 2 drives the weighing and bagging mechanism 3 to move to the initial position Y(0) of the fine flow. The weighing instrument 4 sets the weight value at this position to 0. The PLC control system 5 records the tare weight data G(0)=0 at the initial position.

[0007] S2: The lifting motor 2 drives the weighing and bagging mechanism 3 to rise a certain distance dY. The weighing instrument 4 measures the weight value at this position, and the PLC control system 5 records the tare weight data at this position G(1dY)=Ga1.

[0008] S3: Repeat step S2 until the weighing and bagging mechanism 3 rises to the high position Y(A) of the fine flow. The PLC control system 5 will record multiple tare weight data corresponding to position Y: G(2dY)=Ga2, G(3dY)=Ga3, ..., G(ndY)=Gan.

[0009] S4: The lifting motor 2 drives the weighing and bagging mechanism 3 to descend to the initial position Y(0) of the fine flow;

[0010] S5: The lifting motor 2 drives the weighing and bagging mechanism 3 to descend a certain distance dY. The weighing instrument 4 measures the weight value at this position, and the PLC control system 5 records the tare weight data at this position G(-1dY)=Gb1.

[0011] S6: Repeat step S5 until the weighing and bagging mechanism 3 descends to the low position Y(-B) of the fine flow. The PLC control system 5 will record multiple tare weight data corresponding to position Y: G(-2dY)=Gb2, G(-3dY)=Gb3, ..., G(-mdY)=Gbm.

[0012] S7: The lifting motor 2 drives the weighing and bagging mechanism 3 to rise to the high position of the coarse flow to start normal coarse flow bagging and weighing. When the coarse flow ends, the PLC control system 5 calculates the distance L that the weighing and bagging mechanism 3 descends from the high position of the coarse flow. This distance L is inversely proportional to the bulk density p of the material. Then the lifting motor 2 drives the weighing and bagging mechanism 3 to descend a distance C=k1*L (where k1 is a constant) to continue fine flow feeding and weighing. At the same time, the PLC control system 5 calculates which two recorded position points Y(y) between Y(A) and Y(-B) are between the position Y(y) at this time, and uses interpolation to calculate the tare weight data G(y) corresponding to the position Y(y). The PLC control system 5 transmits this tare weight data G(y) to the weighing instrument 4.

[0013] S8: Weighing instrument 4 recalculates the flow threshold J(y) = J(0) + G(y) based on the tare weight data G(y), where J(0) is the flow threshold at the preset initial flow position Y(0);

[0014] S9: Weighing instrument 4 completes the fine flow feeding and ends the weighing according to the fine flow threshold J(y). Lifting motor 2 drives the weighing and bagging mechanism 3 to descend to the lower position to release the full bag, completing one material bagging and weighing process.

[0015] S10: Repeat steps S7~S9 to complete the bagging and weighing process of a certain amount of material;

[0016] S11: Based on the number of bagging and weighing operations completed by the vertical spiral bagging device and the cumulative working time, perform steps S1 to S6 periodically, and then perform the bagging and weighing process of steps S7 to S10.

[0017] The beneficial effects of this invention are:

[0018] A. After the coarse flow feeding is completed, the distance C of the weighing and bagging mechanism 3 descends is C=k1*L, while the weight of the airborne material at the end of the fine flow feeding is Jf=k2*C*p. Since the distance C is inversely proportional to the bulk density p of the material, Jf= k1* k2* L*p. That is, the weight of the airborne material will be a constant and will not be affected by the change in the bulk density of the material, thereby improving the weighing accuracy.

[0019] B. Using the tare weight data of multiple positions within the initial flow interval, the tare weight value G(y) of the weighing and bagging mechanism 3 at each flow is calculated by interpolation. G(y) is then included in the final flow threshold J(y), thereby eliminating the weighing error caused by the inconsistent tare weight value of the weighing and bagging mechanism 3 at different height positions.

[0020] C. By periodically measuring the tare weight data at multiple points within the initial flow position interval, the influence of tare weight changes caused by wear of the lifting guide rail can be eliminated, maintaining long-term stability of weighing accuracy.

[0021] D. It realizes that the weight of the flying material is not affected by the change of material density, eliminates the influence of tare weight at different height positions, and avoids the influence of tare weight change caused by wear of lifting guide rail. As a result, the weighing accuracy of the vertical spiral bagging device can be greatly improved and can maintain long-term stable operation. The weighing accuracy can be improved to ±0.1%~±0.2%. Attached Figure Description

[0022] Figure 1 This is a front view of the vertical spiral bagging device of the present invention.

[0023] Figure 2 This is a flowchart of the process for determining tare weight at different height positions in this invention.

[0024] Figure 3 This is a flowchart of the weighing and packaging process in this invention. Detailed Implementation

[0025] For detailed embodiments of the present invention, please refer to Figures 1 to 3A method for improving the weighing accuracy of a vertical spiral bagging device, wherein the vertical spiral bagging device includes a lifting column 1, a lifting motor 2 is provided at the upper end of the lifting column 1, the lifting motor 2 is provided with a rotary encoder, the lifting motor 2 drives a weighing bagging mechanism 3 to move up and down along the guide rail on the lifting column 1, the weighing sensor signal of the weighing bagging mechanism 3 is transmitted to a weighing instrument 4, the weighing instrument 4 transmits the weighing weight signal to a PLC control system 5, the weighing instrument 4 receives the weight data returned by the PLC control system 5, and the PLC control system 5 is responsible for coordinating and controlling all actions of the entire vertical spiral bagging device;

[0026] The method for improving the weighing accuracy of the vertical spiral bagging device includes the following steps:

[0027] S0: Set the initial position of the flow to the origin Y(0) of the Y-axis, set the high position of the flow 100mm above the origin Y(0) to Y(100), and set the low position of the flow 100mm below the origin Y(0) to Y(-100).

[0028] S1: The lifting motor 2 drives the weighing and bagging mechanism 3 to move to the initial position Y(0) of the fine flow. The weighing instrument 4 sets the weight value at this position to 0. The PLC control system 5 records the tare weight data G(0)=0 at the initial position.

[0029] S2: The lifting motor 2 drives the weighing and bagging mechanism 3 to rise a distance dY=20mm. The weighing instrument 4 measures the weight value at this position, and the PLC control system 5 records the tare weight data at this position G(20)=Ga1.

[0030] S3: Repeat step S2 until the weighing and bagging mechanism 3 rises to the high position Y(100) of the fine flow. The PLC control system 5 will record four tare weight data corresponding to position Y: G(40)=Ga2, G(60)=Ga3, G(80)=Ga4, G(100)=Ga5.

[0031] S4: The lifting motor 2 drives the weighing and bagging mechanism 3 to descend to the initial position Y(0) of the fine flow;

[0032] S5: The lifting motor 2 drives the weighing and bagging mechanism 3 to descend a distance dY=20mm. The weighing instrument 4 measures the weight value at this position, and the PLC control system 5 records the tare weight data at this position G(-20)=Gb1.

[0033] S6: Repeat step S5 until the weighing and bagging mechanism 3 descends to the low position Y(-100) of the fine flow. The PLC control system 5 will record four tare weight data corresponding to position Y: G(-40)=Gb2, G(-60)=Gb3, G(-80)=Gb, and G(-100)=Gb5.

[0034] S7: The lifting motor 2 drives the weighing and bagging mechanism 3 to rise to the high position of the coarse flow to start normal coarse flow bagging and weighing. When the coarse flow ends, the PLC control system 5 calculates the distance L that the weighing and bagging mechanism 3 descends from the high position of the coarse flow. This distance L is inversely proportional to the bulk density p of the material. Then the lifting motor 2 drives the weighing and bagging mechanism 3 to descend a distance C=k1*L (where k1 is a constant) to continue fine flow feeding and weighing. At the same time, the PLC control system 5 calculates which two positions Y(y) between Y(100) and Y(-100) are between the current position Y(y) and calculates the tare weight data G(y) corresponding to the position Y(y) using the interpolation method. The PLC control system 5 transmits this tare weight data G(y) to the weighing instrument 4.

[0035] S8: Weighing instrument 4 recalculates the flow threshold J(y) = J(0) + G(y) based on the tare weight data G(y), where J(0) is the flow threshold at the preset initial flow position Y(0);

[0036] S9: Weighing instrument 4 completes the fine flow feeding and ends the weighing according to the fine flow threshold J(y). Lifting motor 2 drives the weighing and bagging mechanism 3 to descend to the lower position to release the full bag, completing one material bagging and weighing process.

[0037] S10: Repeat steps S7~S9 to complete the bagging and weighing process of a certain amount of material;

[0038] S11: Based on the number of bagging and weighing operations completed by the vertical spiral bagging device and the cumulative working time, perform steps S1 to S6 periodically, and then perform the bagging and weighing process of steps S7 to S10.

Claims

1. A method for improving the weighing accuracy of a vertical spiral bagging device, wherein the vertical spiral bagging device includes a lifting column (1), a lifting motor (2) is provided at the upper end of the lifting column (1), the lifting motor (2) is provided with a rotary encoder, the lifting motor (2) drives the weighing bagging mechanism (3) to move up and down along the guide rail on the lifting column (1), the weighing sensor signal of the weighing bagging mechanism (3) is transmitted to the weighing instrument (4), the weighing instrument (4) transmits the weighing weight signal to the PLC control system (5), the weighing instrument (4) receives the weight data returned by the PLC control system (5), and the PLC control system (5) is responsible for coordinating and controlling all actions of the entire vertical spiral bagging device; The method for improving the weighing accuracy of the vertical spiral bagging device includes the following steps: S0: Set the initial position of the flow to the origin Y(0) of the Y-axis, set the high position of the flow a distance above the origin Y(0) to Y(A), and set the low position of the flow a distance below the origin Y(0) to Y(-B); S1: The lifting motor (2) drives the weighing and bagging mechanism (3) to move to the initial position Y (0) of the fine flow, the weighing instrument (4) sets the weight value at this position to 0, and the PLC control system (5) records the tare weight data G (0) = 0 at the initial position. S2: The lifting motor (2) drives the weighing and bagging mechanism (3) to rise a distance dY, the weighing instrument (4) measures the weight value at this position, and the PLC control system (5) records the tare weight data at this position G(1dY)=Ga1; S3: Repeat step S2 until the weighing and bagging mechanism (3) rises to the high position Y(A) of the fine flow. The PLC control system (5) will record multiple tare weight data corresponding to position Y: G(2dY)=Ga2, G(3dY)=Ga3, ..., G(ndY)=Gan. S4: The lifting motor (2) drives the weighing and bagging mechanism (3) to descend to the initial position Y (0) of the fine flow; S5: The lifting motor (2) drives the weighing and bagging mechanism (3) to descend a distance dY, the weighing instrument (4) measures the weight value at this position, and the PLC control system (5) records the tare weight data at this position G(-1dY)=Gb1; S6: Repeat step S5 until the weighing and bagging mechanism (3) descends to the low position Y(-B) of the fine flow. The PLC control system (5) will record multiple tare weight data corresponding to position Y: G(-2dY)=Gb2, G(-3dY)=Gb3, ..., G(-mdY)=Gbm. S7: The lifting motor (2) drives the weighing and bagging mechanism (3) to rise to the high position of the coarse flow to start normal coarse flow bagging and weighing. When the coarse flow ends, the PLC control system (5) calculates the distance L that the weighing and bagging mechanism (3) descends from the high position of the coarse flow. This distance L is inversely proportional to the bulk density p of the material. Then the lifting motor (2) drives the weighing and bagging mechanism (3) to descend a distance C=k1*L (where k1 is a constant) to continue fine flow feeding and weighing. At the same time, the PLC control system (5) calculates which two positions Y(y) between Y(A) and Y(-B) are recorded based on the position Y(y) of the weighing and bagging mechanism (3) at this time, and calculates the tare weight data G(y) corresponding to the position Y(y) using the interpolation method. The PLC control system (5) transmits this tare weight data G(y) to the weighing instrument (4). S8: The weighing instrument (4) recalculates the flow threshold J(y) = J(0) + G(y) based on the tare weight data G(y), where J(0) is the flow threshold at the preset flow initial position Y(0); S9: The weighing instrument (4) completes the fine flow feeding and ends the weighing according to the fine flow threshold J(y). The lifting motor (2) drives the weighing and bagging mechanism (3) to descend to the lower position to release the full bag, completing one material bagging and weighing process. S10: Repeat steps S7~S9 to complete the bagging and weighing process of a certain amount of material; S11: Based on the number of bagging and weighing operations completed by the vertical spiral bagging device and the cumulative working time, perform steps S1 to S6 periodically, and then perform the bagging and weighing process of steps S7 to S10.

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