Loss-in-weight scale and method of measuring and controlling it

Abstract

The application provides a loss-in-weight scale and a control method thereof. The loss-in-weight scale comprises a base, a storage hopper, at least one weighing screw and at least one control screw. The discharge port of the storage hopper is located above the feeding port of the control screw, the discharge port of the control screw is located above the feeding port of the weighing screw, and the weighing screw is located above the base. The storage hopper and the weighing screw are connected with the base respectively, the base is provided with a suspension point, the weighing screw is supported on the suspension point, and the suspension point is located on the center line of the discharge port of the control screw. The application realizes the purposes of improving the flow measurement accuracy and the control speed, thereby improving the flow control response speed, expanding the material adaptation range and improving the flow measurement accuracy during material replenishment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of weighing equipment, in particular to a loss-in-weight scale and a measurement and control method thereof. BACKGROUND

[0002] In the prior art, a loss-in-weight scale usually comprises a storage hopper, a screw feeder and a weighing controller, the storage hopper contains material and provides a weighing signal to the weighing controller to measure the weight of the material in the storage hopper. The screw feeder is fixedly connected with the storage hopper to discharge the material in the storage hopper, and the weighing controller measures the discharge rate of the material in the storage hopper and adjusts the feeding rate of the screw feeder to achieve the discharge rate of the material required by the user in combination with the control target of the discharge rate.

[0003] However, as the application has higher and higher requirements for the accuracy of the discharge rate of the material, and the signal-to-noise ratio of the differential measurement of the loss-in-weight scale is small, the flow signal is small, which leads to slow weighing flow of the existing loss-in-weight scale solution and difficulty in meeting the accuracy requirements of high instantaneous material discharge rate control. Since the loss-in-weight scale has the characteristic that it cannot be weighed and measured when the material is replenished, the flow measurement and control accuracy of the loss-in-weight scale when the material is replenished is difficult to meet the application requirements.

[0004] Therefore, improving the measurement and control accuracy and speed of the discharge rate of the material of the loss-in-weight scale will help to expand the application range of the material of the loss-in-weight scale and improve the material adaptability of the loss-in-weight scale.

[0005] Therefore, the skilled in the art designs a loss-in-weight scale to overcome the above technical problems. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the defects that the flow measurement and control accuracy and speed of the loss-in-weight scale in the prior art are difficult to meet the application requirements, and to provide a loss-in-weight scale and a measurement and control method thereof.

[0007] The present application solves the above technical problems by the following technical solutions:

[0008] A loss-in-weight scale, characterized in that the loss-in-weight scale comprises a base, a storage hopper, at least one weighing screw and at least one control screw, the discharge port of the storage hopper is located above the feeding port of the control screw, the discharge port of the control screw is located above the feeding port of the weighing screw, and the weighing screw is located above the base.

[0009] The storage hopper and the weighing screw are respectively connected with the base, a suspension point is arranged on the base, the weighing screw is installed and supported on the suspension point, and the suspension point is located on the center line of the discharge port of the control screw.

[0010] According to one embodiment of the present application, the storage hopper and the control screw are in communication with each other, so that the material flows from the storage hopper into the control screw.

[0011] According to one embodiment of the present application, a soft connection seal is used between the discharge port of the control screw and the weighing screw.

[0012] According to one embodiment of the present application, the storage hopper is installed at the center of the control screw.

[0013] According to one embodiment of the present application, the suspension point is located directly below the connection between the control screw and the weighing screw.

[0014] According to one embodiment of the present application, the weighing screw is provided with a first weighing sensor at the bottom of the weighing screw, and the first weighing sensor is located at the connection between the weighing screw and the base.

[0015] According to one embodiment of the present application, the weighing screw is further provided with a speed measurement system.

[0016] According to one embodiment of the present application, the weighing screw is pressed on the suspension point through a weighing support point located at the bottom of the weighing screw.

[0017] The weighing support point is located on a vertical plane formed by the center line of the feeding port of the weighing screw in the length direction of the weighing screw.

[0018] The first weighing sensor and the weighing support point are horizontally distributed along the length direction of the weighing screw.

[0019] According to one embodiment of the present application, the loss-in-weight scale is further provided with a second weighing sensor, and the second weighing sensor is arranged below the base.

[0020] Alternatively, the second weighing sensor is arranged between the storage hopper and the base, and is used to weigh the weight of the storage hopper.

[0021] The present application also provides a measurement and control method of a loss-in-weight scale, characterized in that the control method of the loss-in-weight scale uses the loss-in-weight scale as described above, and the control method comprises: obtaining a weighing flow rate FW by derivation of a weighing signal WH of the storage hopper, and obtaining a screw scale flow rate FS by multiplication of a weighing signal WS of the weighing screw and a rotation speed signal VS of the weighing screw.

[0022] Using the screw scale flow rate FS as a loss-in-weight scale flow rate, and integrating to obtain a loss-in-weight scale discharge cumulative amount.

[0023] Using the screw scale flow rate FS as a control source, adjusting the speed of the control screw, so as to realize continuous discharge speed control.

[0024] The weighing signal WH is used to realize material level control.

[0025] According to one embodiment of the present application, the control method uses the weighing flow rate FW minus the screw scale flow rate FS as source data for weighing stability judgment, and obtains the extreme value of data in a period of time, and compares it with a preset threshold to judge the stability of the weighing flow rate.

[0026] According to one embodiment of the present application, the control method uses the weighing flow rate FW to correct the screw scale flow rate FS in the non-feeding state and the stable weighing flow rate, that is, FS=FS+k×FW, wherein k is a correction coefficient.

[0027] The positive progress effect of the present application is that:

[0028] The loss-of-weight scale and the measurement and control method thereof eliminate the influence of the loss-of-weight scale bin pressure, feeding interference and the like on the weighing screw by adding a control screw between the weighing screw and the loss-of-weight scale. The speed control through the control screw is isolated from the weighing screw, thereby reducing the influence of the speed control on the weighing screw. The control screw belongs to the loss-of-weight scale, which can preferably measure the influence of the feeding performance of the bin pressure control screw, and is beneficial to eliminating the influence of the bin pressure on the weighing screw control. The connection between the control screw and the weighing screw is arranged inside the equipment, which is beneficial to the equipment management and control. BRIEF DESCRIPTION OF DRAWINGS

[0029] The above and other features, properties and advantages of the present application will become more apparent through the following description with reference to the accompanying drawings and embodiments, in which the same reference numerals are used throughout to designate the same features, wherein:

[0030] Figure 1 It is a structural schematic view of the loss-of-weight scale of the present application.

[0031] Figure 2 It is another structural schematic view of the loss-of-weight scale of the present application.

[0032] REFERENCE NUMERALS

[0033] Base 10

[0034] Storage hopper 20

[0035] Weighing support point 30

[0036] Suspension point 40

[0037] Weighing screw 50

[0038] Control screw 60

[0039] First weighing sensor 51

[0040] Second weighing sensor 11 Detailed Implementation

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0042] Embodiments of the invention will now be described in detail with reference to the accompanying drawings. Preferred embodiments of the invention will now be described in detail, examples of which are shown in the drawings. Wherever possible, the same reference numerals will be used in all the drawings to denote the same or similar parts.

[0043] Furthermore, although the terminology used in this invention is selected from commonly known and used terms, some terms mentioned in this specification may have been selected by the applicant in his or her judgment, and their detailed meanings are explained in the relevant sections of the description herein.

[0044] Furthermore, the invention should be understood not only through the actual terminology used, but also through the meaning implied by each term.

[0045] Figure 1 This is a schematic diagram of one structure of the loss-in-weight scale of the present invention. Figure 2 This is a schematic diagram of another structure of the loss-in-weight scale of the present invention.

[0046] like Figure 1 and Figure 2 As shown, this invention discloses a loss-in-weight scale, which includes a base 10, a storage hopper 20, at least one weighing screw 50, and at least one control screw 60. The discharge port of the storage hopper 20 is located above the inlet of the control screw 60, allowing material to flow from the storage hopper 20 into the control screw 60. The discharge port of the control screw 60 is located above the inlet of the weighing screw 50, which is located above the base 10. The storage hopper 20 and the weighing screw 50 are connected to the base 10. A suspension point 40 is provided on the base 10, and the weighing screw 50 is mounted and supported on the suspension point 40, which is located on the centerline of the discharge port of the control screw 60.

[0047] For example, the weighing screw 50 presses against the suspension point 40 through the weighing support point 30 located at the bottom of the weighing screw 50. The weighing support point 30 is located on the vertical plane formed by the centerline of the weighing screw inlet along the length direction of the weighing screw 50.

[0048] The suspension point 40 is located below the feed inlet of the weighing screw 50, and preferably on the centerline of the discharge outlet of the control screw 60, which helps to eliminate the influence of silo pressure. The suspension point 40 is arranged on the base 10, and the weighing screw 50 is located above the base 10.

[0049] Preferably, the storage hopper 20 and the control screw 60 are interconnected, allowing material to flow from the storage hopper 20 into the control screw 60. It is worth noting that the storage hopper 20 is positioned above the control screw 60, and the material in the storage hopper 20 flows into the control screw 60 by gravity. Whether they are connected is not essential; this is merely a preferred example and is not a limitation.

[0050] A flexible connection seal can preferably be used between the discharge port of the control screw 60 and the weighing screw 50. It is worth noting that the flexible connection seal is not mandatory here, because only powders need to be sealed, while particles do not need to be mechanically connected. This is only a preferred example and is not a limitation.

[0051] The weighing controller measures the material discharge rate in the storage hopper and the feeding rate of the weighing screw, and adjusts the feeding rate of the weighing screw in conjunction with the discharge rate control target to achieve the material discharge rate required by the user.

[0052] Here, the hopper 20 is used to hold materials and provides a weighing signal to the weighing controller to measure the weight of the materials in the hopper 20. The weighing screw 50 is preferably a screw scale equipped with a weighing sensor and a speed measuring system.

[0053] Preferably, both the weighing screw 50 and the control screw 60 are arranged horizontally. This arrangement of double horizontal screws can effectively eliminate the influence of silo pressure.

[0054] More preferably, the storage hopper 20 is installed at the center of the control screw 60, one end of which is connected to the weighing screw 50. The suspension point 40 is located directly below the connection between the control screw 60 and the weighing screw 50. Of course, the suspension point 40 can also be set at the center relative to the discharge port and the inlet port.

[0055] More preferably, a first weighing sensor 51 is provided at the bottom of the weighing screw 50. The first weighing sensor 51 is located at the connection between the weighing screw 50 and the base 10. The first weighing sensor 51 and the weighing support point 30 are horizontally distributed along the length direction of the weighing screw 50 (e.g., Figure 1 and Figure 2 (As shown). The control screw 60 here can be speed-adjusted, and the first weighing sensor 51 can weigh the flow rate obtained from the control screw 60. In addition, a speed measuring system (not shown) can also be installed inside the weighing screw 50.

[0056] Meanwhile, the loss-in-weight scale is also equipped with a second load cell 11. Here, the second load cell 11 can be located below the base 10 (e.g., Figure 1(As shown), or, the second weighing sensor 11 can also be disposed between the storage hopper 20 and the base 10, for weighing the weight of the storage hopper 20 (as shown). Figure 2 (As shown).

[0057] This invention also provides a control method for a loss-in-weight scale, which employs the loss-in-weight scale as described above. The control method includes: obtaining the weighing flow rate FW by differentiating the weighing signal WH from the storage hopper; obtaining the screw scale flow rate FS by multiplying the weighing signal WS from the weighing screw and the rotational speed signal VS of the weighing screw; using the screw scale flow rate FS as the loss-in-weight scale flow rate and integrating it to obtain the cumulative discharge amount of the loss-in-weight scale; using the screw scale flow rate FS as a control source to adjust the speed of the control screw, thereby achieving continuous discharge speed control. The adjustment and implementation methods are general and typically employ PID control. The weighing signal WH is used to achieve material level control.

[0058] For example, preferably, the weight signal WH of the entire device (base weighing method) or the hopper and control screw section (weighing hopper method) is measured by a second weighing sensor to obtain the weighing flow rate FW of the material weighing section. The screw scale flow rate FS (where weight and speed are linearly related) is obtained by the weighing signal WS of the first weighing sensor of the weighing screw. The screw scale flow rate FS is used as the feeding flow rate of the loss-in-weight scale device. The screw scale flow rate FS is used for control, and constant feeding flow rate control is achieved by adjusting the feeding speed of the control screw. The screw scale flow rate FS is corrected using the weighing flow rate FW.

[0059] Preferably, as required by the loss-in-weight scale scenario, the control method uses the weighing flow rate FW minus the screw scale flow rate FS as the source data for weighing stability judgment, calculates the extreme value of the data within a certain period of time, and compares it with a preset threshold to judge the stability of the weighing flow rate.

[0060] More preferably, as required by the loss-in-weight scale scenario, the control method uses the weighing flow rate FW to correct the screw scale flow rate FS in the non-replenishment state and under stable weighing flow rate conditions, i.e., FS = FS + k × FW, where k is the correction coefficient.

[0061] Based on the above description, the loss-in-weight scale and its measurement and control method of the present invention combine a screw scale and a loss-in-weight scale. By incorporating the screw scale into the loss-in-weight scale system, the screw scale is used primarily for weighing and control, fully leveraging its rapid measurement and stable control characteristics. Furthermore, the loss-in-weight scale weighing system is used as a supplementary measure to correct the weighing accuracy and reliability of the screw scale. Thus, during the use of the loss-in-weight scale, the high measurement and control accuracy of the loss-in-weight scale system is maintained, while the control response speed and adaptability to changes in material characteristics are improved, and the weighing control accuracy during material replenishment is also guaranteed.

[0062] The described loss-in-weight scale and its measurement and control method, by incorporating a control screw, avoids the influence of loss-in-weight scale hopper pressure and speed regulation on the measurement of the weighing screw. By controlling the speed regulation of the control screw to extract material from the storage hopper, the measurement and control accuracy of the weighing screw is improved. This eliminates the instability of weighing screw scales and the slow weighing and control of loss-in-weight scales, while retaining the fast measurement and control speed of weighing screw scales and the accurate measurement of loss-in-weight scales. Furthermore, the dual-measurement method avoids the inability to measure during material replenishment of the loss-in-weight scale, making it a superior measurement and control device and method. In the integration of the two devices, the addition of a control screw reduces the influence of loss-in-weight scale hopper pressure and speed regulation on the weighing screw scale.

[0063] In summary, the loss-in-weight scale and its control method of this invention eliminate the influence of silo pressure and feeding interference on the weighing scale by adding a control screw between the weighing screw and the loss-in-weight scale. Speed ​​control, achieved through the control screw, is isolated from the weighing screw, reducing the impact of speed regulation on the weighing screw. Assigning the control screw to the loss-in-weight scale allows for better measurement of the influence of silo pressure on the feeding performance of the control screw, thus helping to eliminate the influence of silo pressure on the weighing screw control. Placing the connection between the control screw and the weighing screw inside the equipment facilitates equipment management.

[0064] The loss-in-weight scale and its measurement and control method of the present invention integrate the features of existing loss-in-weight scales and weighing screw scales. By using the weighing screw scale, the feeding flow measurement speed and accuracy are improved, and by using the loss-in-weight scale, the weighing reliability and stability of the weighing screw scale are corrected, thereby improving the feeding measurement and control speed and accuracy of the loss-in-weight scale. This will help to expand the application scope of the loss-in-weight scale and improve its material adaptability.

[0065] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A loss-in-weight scale characterized by, The loss-in-weight scale comprises a base, a storage hopper, at least one weighing screw and at least one control screw, the discharge port of the storage hopper is above the feeding port of the control screw, the discharge port of the control screw is above the feeding port of the weighing screw, and the weighing screw is above the base; The storage hopper and the weighing screw are connected with the base respectively, the base is provided with a suspension point, the weighing screw is supported on the suspension point, and the suspension point is on the center line of the discharge port of the control screw; The bottom of the weighing screw is provided with a first weighing sensor for weighing the material flow obtained from the control screw, and the loss-in-weight scale is further provided with a second weighing sensor for measuring the weight signal of the entire device or the storage hopper and the control screw part; The product of the weighing signal WS of the weighing screw and the rotating speed signal VS of the weighing screw is used to obtain the screw scale flow FS, the screw scale flow FS is used as a control source to adjust the speed of the control screw, so that continuous discharge speed control is realized.

2. The loss-in-weight scale of claim 1 wherein, The storage hopper and the control screw are in communication with each other, so that the material flows from the storage hopper into the control screw.

3. The loss-in-weight scale of claim 1 wherein, The discharge port of the control screw and the weighing screw are sealed by a soft connection.

4. The loss-of-weight scale of claim 1, wherein, The storage hopper is installed at the center of the control screw.

5. The loss-of-weight scale of claim 4, wherein, The suspension point is directly below the connection between the control screw and the weighing screw.

6. The loss-of-weight scale of claim 1, wherein, The first weighing sensor is located at the connection between the weighing screw and the base.

7. The loss-of-weight scale of claim 6, wherein, The weighing screw is further provided with a speed measuring system.

8. The loss-of-weight scale of claim 6, wherein, The weighing screw is pressed on the suspension point through a weighing support point at the bottom of the weighing screw; The weighing support point is located on the vertical plane formed by the center line of the feeding port of the weighing screw in the length direction of the weighing screw; The first weighing sensor and the weighing support point are horizontally distributed along the length direction of the weighing screw.

9. The loss-of-weight scale of claim 1, wherein, The second weighing sensor is arranged below the base. Or the second weighing sensor is arranged between the storage hopper and the base to weigh the storage hopper.

10. A method for measuring and controlling a loss-in-weight scale, characterized in that, The control method of the loss-in-weight scale uses the loss-in-weight scale according to any one of claims 1-9, and the control method comprises: obtaining a weighing flow FW by derivation of a weighing signal WH of the storage hopper, and obtaining a screw scale flow FS by the product of a weighing signal WS of the weighing screw and a rotating speed signal VS of the weighing screw; The screw scale flow FS is used as the loss-in-weight scale flow to obtain the cumulative amount of loss-in-weight scale discharge by integration. The screw scale flow FS is used as a control source to adjust the speed of the control screw, so that continuous discharge speed control is realized. The weighing signal WH is used to realize material level control.

11. The method of claim 10, wherein the step of determining the mass of the object comprises the steps of: determining the mass of the object based on the measured force and the measured distance. The control method uses the weighing flow FW minus the screw scale flow FS as source data for weighing stability judgment, and obtains the extreme value of data in a period of time, which is compared with a preset threshold to judge the stability of the weighing flow.

12. The method of claim 11, wherein the step of determining the mass of the object comprises the steps of: determining the mass of the object based on the measured force and the measured distance. In the non-replenishment state and the case where the weighing flow is stable, the weighing flow FW is used to correct the screw scale flow FS, that is, FS=FS+k×FW, wherein k is a correction coefficient.

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