CN217276493U - Tobacco shred mass flow belt weigher calibrating device - Google Patents
Tobacco shred mass flow belt weigher calibrating device Download PDFInfo
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- CN217276493U CN217276493U CN202220774360.7U CN202220774360U CN217276493U CN 217276493 U CN217276493 U CN 217276493U CN 202220774360 U CN202220774360 U CN 202220774360U CN 217276493 U CN217276493 U CN 217276493U
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Abstract
The utility model relates to a tobacco technology process detects technical field, concretely relates to pipe tobacco mass flow belt weigher calibrating device, this pipe tobacco mass flow belt weigher calibrating device mainly includes the pipeline tighrening ring, the flow balance valve, the complete machine support, the hose coupling pipe, fixed hinge, the chamber of expanding gradually, horizontal grid plate, the free flow chamber, the laval spray tube, the display control screen, the connecting wire, the actor, the lift adjustment structure, pneumatic executive structure, the injection part bracing piece, lift platform, compressed air entry link. Through this pipe tobacco mass flow belt weigher calibrating device, can realize carrying out the check-up work regularly to cigarette enterprise throwing workshop pipe tobacco mass flow belt weigher. The tobacco shred mass flow belt scale calibrating device has the characteristics of no need of additional standard weights or material objects, good calibration convenience of the tobacco shred mass flow belt scale, short calibration time, low labor consumption, reliable result and low interference of human factors of an operator.
Description
Technical Field
The utility model relates to a tobacco technology process detects technical field, concretely relates to pipe tobacco mass flow belt weigher calibrating device.
Background
The zero point and the measuring range of the belt weigher can shift to different degrees due to various factors in the working process of the belt weigher. For example: the conveyer belt adhesion material, conveyer belt tension change or off tracking, conveyer belt shortening or extension etc. that temperature variation leads to. In order to ensure the metering accuracy of the belt weigher, the belt weigher needs to be calibrated regularly.
For the special material of tobacco shred, according to the requirements of the national tobacco monopoly for the cigarette process standard, the measuring and calibrating method of the electronic belt weigher is divided into two methods: one is a load simulation method, and the other is a material passing method. The analog load method is that standard weights with known weight are uniformly placed on the weighing section of the electronic belt scaleAnd (4) operating, recording the accumulated display value of the electronic belt scale after the weights uniformly flow through the electronic belt scale, repeatedly measuring and calculating the average value of the accumulated display value. Requirement P in the test s Not less than 50 kg. The calculation formula is as follows:
in the formula, delta ds The measurement precision (%) of the electronic belt scale is P s Cumulative weight (kg) of weight placed, C s The cumulative weight (kg) is displayed for the electronic belt scale. The material passing method includes weighing tobacco material (over 50kg), passing the weighed tobacco material through electronic belt scale or collecting all the material at the outlet according to the rated flow of the equipment, weighing, and comparing with the accumulated value of the electronic belt scale. The measurement was repeated and the average value thereof was calculated. Theoretically, the two calibration methods all adopt the incremental stacking principle, and only the properties of stacked materials are different.
For the analog load method, a series of operations such as placing a standard weight, recovering the standard weight, counting the average value, etc. are required by an operator on site. Meanwhile, errors caused by human factors cannot be avoided in the placing process, and if standard weights are placed, the lifting action of the standard weights can affect the scale frame of the auxiliary belt scale to cause errors. Therefore, the analog load method requires a certain amount of labor, and a certain error may be introduced during the operation process of the field personnel. The operation process of the material passing method is complicated, the tobacco materials participating in calibration need to be statically weighed at first, and the carrying and weighing labor amount is very heavy. In the process of passing, the physical properties (tobacco shred structure and moisture content) of the tobacco shred materials are changed, which is not beneficial to the reutilization of the tobacco shred materials. Furthermore, the introduction of metering errors by the static hopper scale of the weighing hopper also increases the calibration errors of the real-world overfeeding method.
In view of this, there is a need to develop a calibration device for a tobacco shred mass flow belt weigher, which does not require additional standard weights or material objects, can improve the calibration convenience of the tobacco shred flow belt weigher, and has the advantages of short calibration time, low manpower consumption, reliable result and small human factor interference of an operator.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem that prior art method exists, improve the intelligent level of pipe tobacco flow calibration, promote the convenience of belt weigher calibration, reduce manpower resource consumption, reduce the interference of operating personnel human factor, the utility model aims at realizing through following technical scheme:
a tobacco shred mass flow belt weigher calibration device comprises: pipeline tighrening ring, flow balance valve, complete machine support, hose coupling, fixed hinge, the chamber that expands gradually, horizontal grid plate, free flow chamber, laval spray tube, display control screen, connecting wire, actor, lift adjustment structure, pneumatic executive structure, injection part bracing piece, lift platform, compressed air entry link. The whole machine support is fixed above the conveying belt, the inner side of the pipeline fastening ring is wrapped with the compressed air inlet connecting end, and the outer side of the pipeline fastening ring is connected with the whole machine support. One end of the compressed air inlet connecting end is connected with compressed air, and the other end of the compressed air inlet connecting end is connected with the flow balance valve. The flow balance valve is connected with the flexible connecting pipe. The lower side of the soft connecting pipe is connected with the gradually expanding cavity through a circular pipe. And a horizontal air distribution plate is arranged at the tail end of the gradually expanding cavity. The lower end of the horizontal air distribution plate is connected with a free flow cavity, and the free flow cavity is connected with a Laval nozzle. The lifting platform is arranged on one side of the whole machine support, and the horizontal height of the lifting platform is adjusted through a lifting adjusting structure on the lifting platform. The display control screen is connected with the actuator through a connecting line and controls the pneumatic execution structure through the actuator, so that the cylinder of the pneumatic execution structure contracts or expands. The airflow jet part and the lifting platform are respectively connected with the pneumatic execution structure through fixed hinges. The jet part support rod and the airflow jet part are connected through a fixed hinge.
The device structure, the installation mode, the working principle and the working process of the utility model are further explained as follows:
the whole machine bracket is fixed above the transmission belt, and compressed gas sequentially passes through the compressed air inlet connecting end, the flow balance valve, the flexible connecting pipe, the gradually expanding cavity, the air distribution plate, the free flow cavity and the Laval nozzle along the flowing direction of the compressed gas and is finally sprayed on the transmission belt. The inner side of the pipeline fastening ring is wrapped with a compressed air inlet connecting end, and the outer side of the pipeline fastening ring is connected with the whole machine support and used for fixing the compressed air inlet connecting end. One end of the compressed air inlet connecting end is connected with compressed air, and the other end of the compressed air inlet connecting end is connected with the flow balance valve. And the flow balance valve is arranged on the lower side of the compressed air inlet connecting end and used for regulating the flow of the compressed air. The flow balance valve is connected with the flexible connecting pipe, the flexible connecting pipe provides displacement compensation for free retraction and extension of the airflow injection part (comprising a fixed hinge, a gradually expanding cavity, an air distribution plate, a free flow cavity and a Laval nozzle), and meanwhile vibration and noise of the pipe system are reduced and absorbed, so that normal operation of the system is protected to a certain extent. The lower side of the soft connecting pipe is connected with a round pipe, and the diameter of the round pipe is equal to that of the compressed air inlet section. The air flow enters the gradually expanding cavity after passing through the flow balance valve, the flexible connecting pipe and the circular pipe. And a horizontal air distribution plate is arranged at the tail end of the divergent cavity and used for regulating the air flow again, improving the uniformity of the flow and weakening the effect of a flow boundary layer. The gas flow then enters the free-flow chamber. Finally, the gas stream enters a laval nozzle and is sprayed onto the conveyor belt.
The lifting platform is arranged on one side of the whole machine bracket and is used for connecting and supporting the pneumatic execution structure, the actuator and the jet part supporting rod. The horizontal height of the lifting platform is adjusted through the lifting adjusting structure. The display control screen is connected with the actuator through a connecting line, and controls the pneumatic execution structure through the actuator, so that the cylinder of the pneumatic execution structure contracts or expands, and the arrangement and the retraction of the airflow injection part (comprising a fixed hinge, a gradually expanding cavity, a grid plate, a free flow cavity and a Laval nozzle) are realized. The airflow jet part and the lifting platform are respectively connected with the pneumatic execution structure through fixed hinges. The jet part support rod and the airflow jet part are connected through a fixed hinge.
Furthermore, a cushion ring is arranged between the inner side of the pipeline fastening ring and the pipeline of the compressed air inlet connecting end, so that the influence of vibration caused by the action of the pneumatic execution structure on the pipeline is weakened. The inner diameter of the pipeline fastening ring can be adjusted through the bolt fastener so as to adapt to the compressed air inlet connecting ends with different outer diameters.
Further, the flow balance valve adopts a pneumatic regulating valve to ensure the food safety requirement of the cut tobacco used as the food absorption product. The flow precision of the flow balance valve is within 5 percent.
Furthermore, the gradually-expanding cavity is in a regular quadrangular frustum pyramid structure. The upper bottom surface and the lower bottom surface are square, and the side length of the upper bottom surface is larger than the outer diameter of the connecting circular pipe; the side length of the lower bottom surface is 1.5 times larger than that of the upper bottom surface so as to realize the gradual widening process of the airflow. The height of the regular quadrangular frustum pyramid is not less than the side length of the upper bottom surface so as to weaken airflow pulsation and ensure full development of flow.
Furthermore, the horizontal air distribution plate is a geometric structure with round holes uniformly formed on the horizontal plate. The ventilation degree of the horizontal air distribution plate is more than or equal to 50 percent so as to ensure that the throttling loss of the air distribution plate is in a reasonable range. The radius of the round hole is less than or equal to 8mm, and the number of the holes is set according to the ventilation degree.
Further, the free flow chamber is the cavity cuboid structure, and its height is not less than gradually expands the chamber height to ensure the abundant development that compressed air flows.
Furthermore, the front half part of the Laval nozzle is contracted to a narrow throat from big to small, and the narrow throat is expanded to the bottom of the tube from small to big. The gas in the pipe body flows into the front half part of the nozzle under high pressure, and escapes from the rear half part after passing through the narrow throat, and the gas flow generates an isentropic expansion process in the Laval nozzle. The number of the Laval nozzles is more than or equal to 4, and the Laval nozzles are axially symmetrical and centrosymmetrical with respect to the main flow direction of the airflow in the circular tube.
Furthermore, the geometrical design of the laval nozzle ensures that the isentropic flow velocity in the front half convergent duct can only be continuously changed to Mach number Ma 1, so that the air flow can be changed from subsonic speed to sonic speed in the laval nozzle.
Further, the display control screen is configured to: (1) controlling the lifting adjusting structure and setting the horizontal height of the lifting platform; (2) the pneumatic ejection component is connected with the actuator through a connecting line, and the actuator controls the pneumatic execution structure to realize the arrangement and the retraction of the pneumatic ejection component. (3) Displaying real-time pressure of compressed air at an inlet of the equipment; (4) displaying the transmission speed of the transmission belt; (5) and displaying the calibration analog value of the flow of the tobacco shred material. In the actual calibration process in scene, the display control screen can be operated by one key, and great convenience is brought to operators.
Further, the stroke of the cylinder piston of the pneumatic actuator enables the air jet member to rotate 60 ° or more.
Furthermore, an emergency stop switch is arranged on the actuator, so that the air jet part can be retracted and the compressed air can be cut off at any time, the flexible control on various risks caused by unknown factors in production is realized, and the production safety is ensured.
Furthermore, the lifting platform is arranged on one side of the whole machine support through a lifting adjusting structure, and the adjusting range of the lifting adjusting structure is larger than 10 cm.
The detection device is suitable for accurate calibration of the belt weigher for the tobacco mass flow in the tobacco shred manufacturing workshops of cigarette enterprises. The device can be permanently installed on the tobacco shred measuring belt weigher, and can meet the requirement of frequent calibration work on the tobacco shred mass flow belt weigher.
Advantageous effects
Compared with the prior art, the utility model discloses have as follows and show the progress:
the utility model provides a pipe tobacco mass flow belt weigher calibrating device compares in traditional calibrating device, the utility model discloses do not need standard weight or material in kind, and reduced manpower consumption, promoted the convenience of calibration, improved the intelligent level of pipe tobacco flow calibration. The tobacco shred mass flow belt weigher calibrating device needs shorter calibrating time. Traditional analog load method in the weight place on the belt weigher, the belt weigher drives weight horizontal migration and the weight and withdraws the process and go on one section interval to whole calibration process, and adopt the utility model discloses a device, calibration process goes on in succession, and required time is shorter. In traditional material object punishment in advance method, at first occupy a large amount of times to the static measurement of material, and the utility model discloses as long as place the air jet part, put through the air supply can develop calibration work immediately. Therefore, the utility model discloses a calibrating device is shorter than material passing method required time in kind equally. In addition, this pipe tobacco mass flow belt weigher calibrating device has effectively overcome the influence of human factor in traditional calibration mode, and the result is more reliable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a tobacco shred mass flow belt scale calibration device provided in an embodiment of the present invention;
fig. 2 is a schematic view of a retracted state of an air jet component of the calibrating apparatus for a tobacco shred mass flow belt weigher according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a three-dimensional numerical simulation flow of the calibration method for the tobacco shred mass flow belt weigher according to the embodiment of the present invention;
fig. 4 is a schematic diagram of the calculation meshing of the calibration method of the belt weigher for tobacco shred mass flow rate provided by the embodiment of the present invention;
fig. 5 is a schematic view of a velocity field profile of a calculation result of the calibration method for the tobacco shred mass flow belt weigher according to the embodiment of the present invention.
Reference numerals:
1. a pipeline fastening ring; 2. a flow balancing valve; 3. a whole machine bracket; 4. a flexible connection pipe; 5. fixing the hinge; 6. a gradually expanding cavity; 7. a wind distribution plate; 8. a free-flow chamber; 9. a laval nozzle; 10. a transfer belt; 11. Displaying a control screen; 12. a connecting wire; 13. an actuator; 14. a lifting adjusting structure; 15. a pneumatic actuator structure; 16. a jet member support rod; 17. a lifting platform; 18. compressed air inlet connection end.
Detailed Description
In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention based on the embodiments of the present invention.
As shown in fig. 1, a tobacco shred mass flow belt weigher calibration device comprises: the device comprises a pipeline fastening ring 1, a flow balance valve 2, a whole machine support 3, a flexible connecting pipe 4, a fixed hinge 5, a gradually-expanding cavity 6, a horizontal air distribution plate 7, a free flow cavity 8, a Laval nozzle 9, a display control screen 11, a connecting wire 12, an actuator 13, a lifting adjusting structure 14, a pneumatic execution structure 15, an injection part supporting rod 16, a lifting platform 17 and a compressed air inlet connecting end 18. The whole machine bracket 3 is fixed above the transmission belt 10. The inner side of the pipeline fastening ring 1 is wrapped with a compressed air inlet connecting end 18, and the outer side is connected with the whole machine bracket 3. The compressed air inlet connection 18 is connected at one end to compressed air and at the other end to the flow balance valve 2. The flow balance valve 2 is connected with a flexible connecting pipe 4. The lower side of the soft connecting pipe 4 is connected with the gradually expanding cavity 6 through a circular pipe. And a horizontal air distribution plate 7 is arranged at the tail end of the divergent cavity 6. The lower end of the horizontal air distribution plate 7 is connected with a free flow cavity 8, and the free flow cavity 8 is connected with a Laval nozzle 9. The lifting platform 17 is installed on one side of the whole machine bracket 3, and the horizontal height of the lifting platform 17 is adjusted through the lifting adjusting structure 14 on the lifting platform 17. The display control screen 11 is connected with the actuator 13 through a connecting line 12, and controls the pneumatic actuator 15 through the actuator 13, so that the cylinder of the pneumatic actuator 15 contracts or expands. The airflow injection component and the lifting platform 17 are respectively connected with the pneumatic execution structure 15 through the fixed hinge 5. The jetting member support rod 16 and the air jetting member are connected by a fixed hinge 5.
The device structure, the installation mode, the working principle and the working process of the utility model are further explained as follows:
the whole machine bracket 3 is fixed above the transmission belt 10. The compressed air passes through the compressed air inlet connecting end 18, the flow balance valve 2, the flexible connecting pipe 4, the divergent cavity 6, the horizontal air distribution plate 7, the free flow cavity 8 and the laval nozzle 9 in sequence along the flowing direction of the compressed air, and is finally sprayed on the transmission belt 10. The inner side of the pipeline fastening ring 1 is wrapped with a compressed air inlet connecting end 18, and the outer side of the pipeline fastening ring is connected with the whole machine bracket 3 and used for fixing the compressed air inlet connecting end 18. The compressed air inlet connection 18 is connected at one end to compressed air and at the other end to the flow balance valve 2. A flow balancing valve 2 on the underside of the compressed air inlet connection 18 for flow regulation of the compressed air. The flow balance valve 2 is connected with a flexible connection pipe 4, the flexible connection pipe 4 provides displacement compensation for free retraction of an airflow injection component (comprising a fixed hinge 5, a gradually expanding cavity 6, a horizontal air distribution plate 7, a free flow cavity 8 and a Laval nozzle 9), vibration and noise of a pipe system are reduced and absorbed, and normal operation of the system is protected to a certain extent. A round tube is connected to the lower side of the flexible connecting tube 4, and the diameter of the round tube is equal to that of the compressed air inlet section. The air flow enters the gradually expanding cavity 6 after passing through the flow balance valve 2, the flexible connecting pipe 4 and the circular pipe. And a horizontal air distribution plate 7 is arranged at the tail end of the divergent cavity 6, and the horizontal air distribution plate 7 is used for regulating the air flow again, improving the uniformity of the flow and weakening the effect of a flow boundary layer. The gas flow then enters the free-flow chamber 8. Finally, the gas flow enters a laval nozzle 9 and is sprayed on a conveyor belt 10.
The lifting platform 17 is arranged at one side of the whole machine bracket 3 and is used for connecting and supporting the pneumatic actuating structure 15, the actuator 13 and the spraying part supporting rod 16. The horizontal height of the lifting platform 17 is adjusted by the lifting adjusting structure 14. The display control screen 11 is connected with the actuator 13 through a connecting line 12, and controls the pneumatic actuating structure 15 through the actuator 13, so that the cylinder of the pneumatic actuating structure 15 contracts or expands, and the arrangement and the retraction of the airflow injection part (comprising the fixed hinge 5, the divergent cavity 6, the air distribution plate, the free flow cavity 8 and the Laval nozzle 9) are realized. The airflow injection component and the lifting platform 17 are respectively connected with the pneumatic execution structure 15 through the fixed hinge 5. The injection member support rod 16 and the air stream injection member are connected by a fixed hinge 5.
Further, a cushion ring is provided between the inner side of the pipeline fastening ring 1 and the compressed air inlet connection end 18 to reduce the influence of vibration caused by the action of the pneumatic actuator 15 on the pipeline. The inner diameter of the pipe fastening ring 1 can be adjusted by means of a screw fastener to accommodate compressed air inlet connection ends 18 of different outer diameters.
Further, the flow balance valve 2 adopts a pneumatic regulating valve to ensure the food safety requirement of the tobacco shreds used as the food suction. The flow accuracy of the flow balance valve 2 is within 5%.
Further, the divergent cavity 6 is in a regular quadrangular frustum pyramid (trapezoidal frustum) structure. The upper bottom surface and the lower bottom surface are square, and the side length of the upper bottom surface is larger than the outer diameter of the connecting circular pipe; the side length of the lower bottom surface is 1.5 times larger than that of the upper bottom surface so as to realize the gradual widening process of the airflow. The height of the regular quadrangular frustum pyramid is not less than the side length of the upper bottom surface, so that the airflow pulsation is weakened, and the full development of the flow is ensured.
Further, the horizontal air distribution plate 7 is a geometric structure with round holes uniformly formed on the horizontal plate. The ventilation degree of the horizontal air distribution plate 7 is more than or equal to 50 percent so as to ensure that the throttling loss of the air distribution plate is in a reasonable range. The radius of the round hole is less than or equal to 8mm, and the number of the holes is set according to the ventilation degree.
Further, the free flow chamber 8 is a hollow cuboid structure, and the height of the free flow chamber is not less than that of the gradually expanding chamber 6, so that the sufficient development of the flow of the compressed air is ensured.
Further, the front half part of the laval nozzle 9 is contracted from big to small to the middle to a narrow throat, and the narrow throat is expanded from small to big to the bottom of the tube. The gas in the pipe body flows into the front half part of the nozzle under high pressure, passes through the narrow throat and then escapes from the rear half part, and the gas flow generates an isentropic expansion process in the Laval nozzle 9. The number of the Laval nozzles 9 is more than or equal to 4 (even number), and the Laval nozzles are axisymmetric and centrosymmetric with respect to the main flow direction of the airflow in the circular tube.
Further, the geometry of the laval nozzle 9 is designed to ensure that the isentropic flow velocity in the first half of the convergent duct can be varied continuously only to Ma (mach number) 1, allowing the flow to move from subsonic to sonic speeds in the laval nozzle 9.
Further, the display control screen 11 is configured to: (1) controlling the lifting adjusting structure 14 and setting the horizontal height of the lifting platform 17; (2) the pneumatic actuator 15 is controlled by the actuator 13 through the connecting line 12, and the air jet part is arranged and retracted. (3) Displaying real-time pressure of compressed air at an inlet of the equipment; (4) displaying the conveying speed of the conveying belt 10; (5) and displaying the calibration analog value of the flow of the tobacco shred material. In the actual calibration process on site, the display control screen 11 can be operated by one key, so that great convenience is brought to operators.
Further, the stroke of the cylinder piston of the pneumatic actuator 15 enables the air jet member to rotate 60 ° or more, as shown in fig. 2.
Further, an emergency stop switch is arranged on the actuator 13, so that the air jet part can be retracted and compressed air can be cut off at any time, flexible control of various risks caused by unknown factors in production is realized, and production safety is guaranteed.
Further, the lifting platform 17 is installed on one side of the whole machine support 3 through the lifting adjusting structure 14, and the adjusting range of the lifting adjusting structure 14 is larger than 10 cm.
A method for calibrating a tobacco shred mass flow belt weigher is shown in figure 3 and comprises the following steps:
step1. collection and analysis of data: collecting various basic data, wherein the basic data comprises but is not limited to a tobacco shred mass flow belt scale design drawing, tobacco shred mass flow belt scale operation data and traditional simulated load method historical verification data; when the data is used, the data is carefully analyzed and checked, problems are found and carefully examined, and possible errors and careless mistakes are eliminated.
Step2, initially determining the structure of the airflow field: and preliminarily determining the structure of the airflow field according to the empirical values of the air flow and the flow speed required by spraying on the belt scale, in combination with the flow characteristics of the airflow and comprehensively considering the on-way flow loss and the throttling loss. The initial fixed flow field structure corresponds to the basic data of the tobacco shred measuring belt scale.
Step3. model establishment and simulation method determination: establishing three-dimensional physical models of the inner and outer areas of the jet part where the airflow is positioned; according to the simulation efficiency and the tobacco flow calibration precision, selecting a proper control equation discrete method (a finite difference method, a finite element method and a finite volume method), a turbulent mathematical model and a flow field solving algorithm, and accordingly establishing CFD simulation software.
Step Step4. simulation solving: establishing boundary constraint conditions and calculating area discretization; iterative solution and grid independence verification; and (4) storing and analyzing a simulation result and optimizing and reconstructing a flow field structure.
Step Step5. design of auxiliary structure: based on the simulation result of the airflow field, corresponding auxiliary equipment structures are designed, including but not limited to a complete machine bracket 3, a lifting platform 17, a lifting adjusting structure 14, a pneumatic execution structure 15, an actuator 13, an injection part supporting rod 16, a fixed hinge 5, a pipeline fastening ring 1, and a proper flow balance valve 2, a soft connecting pipe 4 and a display control screen 11 are selected.
And step6, transformation implementation and application. The production line tobacco shred mass flow belt weigher is reformed and finally applied to the actual production process.
As a preferred embodiment of the present invention, Step2 specifically includes the following steps:
and step Step201, presetting the pressure of the jet air flow acting on the belt weigher. According to the flow of tobacco shred materials in the actual production process, the time-sharing pressure force applied to the local area of the belt scale is determined, and the time-sharing pressure force is used as the preset pressure of the jet air flow acting on the belt scale.
And step Step202, determining an empirical value of the gas velocity at the outlet of the Laval nozzle 9. Assuming that the jet air flow has no reverse speed (horizontal tangential flow) after acting on the belt, the empirical value of the air speed at the outlet of the Laval nozzle 9 is determined according to the law of conservation of momentum and the combination of the preset pressure acting on the belt scale.
And step S203, according to the Laval nozzle 9 outlet gas velocity empirical value, combining the gas flow characteristics, and comprehensively considering various flow losses (along-way flow loss coefficient and throttling loss coefficient), preliminarily determining the structure of the gas flow field, including but not limited to the resistance coefficient of the flow balance valve 2, the ventilation degree of the air distribution plate, the number of the Laval nozzles 9, the throat area of the Laval nozzle 9 and other along-way sectional areas of all sections. The initial fixed flow field structure corresponds to the basic data of the tobacco shred measuring belt scale.
As a preferred embodiment of the present invention, Step4 specifically includes the following steps:
step401, boundary constraint condition establishment and calculation of area discretization. And determining the boundary constraint condition of the jet air flow according to the actual boundary and the space influence area of the geometric body. And dividing the grids of the three-dimensional models in different regions according to the region discretization method. The calculation zones include, but are not limited to, the pipe sections, the diverging chamber 6, the air distribution plate, the free flow chamber 8, the laval nozzle 9, and the end of the conveyor belt 10. The size of the airflow field CFD calculation grid needs to be determined by comprehensively considering the accuracy of the gas phase field, the smoothness of time and space changes and the calculation consumption. The grid density of the heavy point areas such as the parts (near the horizontal grid plate 7 and inside the Laval nozzle 9) with severe flow field changes is improved, so that the numerical simulation precision is improved.
Step Step402. iterative solution and grid independence verification: and (4) carrying out numerical iteration solution and carrying out grid sensitivity analysis to determine the optimal CFD grid size of the gas phase field and realize grid independence verification. If the requirements are met, entering the next step; otherwise, the computational grid needs to be modified, and the Step is shifted to Step401.
Step403, simulation result storage, analysis and flow field structure optimization reconstruction: storing and analyzing the simulation result, determining the relationship between the pressure at the inlet of the equipment and the pressure value of the air flow sprayed to the belt weigher, finally converting the relationship into the relationship between the pressure at the inlet of the equipment and the simulation value of the tobacco shred flow, and optimizing and reconstructing the structure of each component according to the relationship. If the design requirements are met, entering the next step; otherwise, the structural size of each component needs to be modified, and the Step is shifted to Step201.
The detection device is suitable for accurate calibration of the tobacco shred mass flow belt weigher in the tobacco shred manufacturing workshop of each cigarette enterprise. The device can be permanently installed on the tobacco shred measuring belt weigher, and can meet the requirement of frequent calibration work on the tobacco shred mass flow belt weigher.
Take the calibration of a tobacco shred mass flow belt weigher in a shred manufacturing workshop of a certain cigarette enterprise as an example. The utility model provides a pair of pipe tobacco mass flow belt weigher calibration three-dimensional numerical simulation process based on CFD, include:
step1. collection and analysis of data: collecting various basic data, and carrying out careful analysis and check on the data.
And step Step201, determining the pressure equalizing force of the local area of the belt scale to be 500Pa according to the flow of the tobacco shred materials in the actual production process, and using the pressure equalizing force as the preset pressure of the jet air flow acting on the belt scale.
And step202, assuming that the jet air flow has no reverse speed (horizontal tangential flow) after acting on the belt, and determining that the air speed empirical value at the outlet of the Laval nozzle 9 is 150m/s according to a momentum conservation law and the combination of preset pressure acting on the belt scale.
Step Step203. initial determination of the structure of the airflow field: according to the empirical values of the air flow and the flow speed required by being sprayed on the belt weigher, the airflow characteristics are combined, the on-way flow loss and the throttling loss are comprehensively considered, and the airflow field is preliminarily determined as follows:
(1) the air flow rate is initially set to 0.4m 3 In/s (normal pressure).
(2) The on-way flow loss coefficient was 0.05, and the throttling loss coefficient was 0.5.
(3) The internal diameter of the compressed air inlet connection end 18 is 110 mm.
(4) The side length of the upper bottom surface of the gradually expanding cavity 6 is 130mm, the side length of the lower bottom surface is 200mm, and the height is 130 mm.
(5) The radius of the round hole opened by the horizontal air distribution plate 7 is 8mm, the number of the holes is 100, and the holes are uniformly opened along the plate surface. The ventilation degree of the air distribution plate is 50%.
(6) The free-flow chamber 8 is 200mm in height.
(7) The number of the Laval nozzles 9 is 4, and the Laval nozzles are axisymmetric and centrosymmetric with respect to the main flow direction of the airflow in the circular tube.
(8) The radius of the cross section of the inlet of the Laval nozzle 9 is 20mm, the radius of the cross section of the throat part is 10mm, and the radius of the cross section of the outlet is 25 mm. The length of the narrow throat section of the laval nozzle 9 from the inlet section is 100 mm, and the length of the narrow throat section of the laval nozzle 9 from the outlet section is 300 mm. The distance between the exit of the laval nozzle 9 and the belt was 35 mm.
(9) The resistance coefficient of the flow balance valve 2 is 0.05.
Step3. model establishment and simulation method determination: establishing three-dimensional physical models of the inner and outer areas of the jet part where the airflow is positioned; according to the simulation efficiency and the tobacco flow calibration precision, a control equation discrete method is selected to be a finite volume method, a Standard k-epsilon model is adopted as a turbulent flow mathematical model, a SIMPLE algorithm is adopted as a flow field solving algorithm, a solid non-slip wall function is adopted as a near wall function, and OpenFoam open source software is adopted as CFD simulation software.
Step401, boundary constraint condition establishment and calculation of area discretization. And determining the boundary constraint condition of the jet air flow according to the actual boundary and the space influence area of the geometric body. The air inlet is the "pressure inlet boundary condition" and the outlet is the "free flow boundary condition". According to the area discretization method, the meshes of the three-dimensional models of the segments are divided by areas, as shown in fig. 4. The grid density of the heavy point areas such as the parts (near the horizontal air distribution plate 7 and inside the Laval nozzle 9) with severe flow field changes is improved. The total number of grids is 67.73 ten thousand, and the total number of grids is 145.67 ten thousand faces and 19.18 ten thousand nodes. Minimum grid volume of 6.04X 10 -10 m 3 Maximum grid volume of 8.73X 10 -7 m 3 。
Step Step402. iterative solution and grid independence verification: and (3) carrying out numerical iteration solution and carrying out grid sensitivity analysis to determine the optimal CFD grid size of the gas phase field and realize grid independence verification. The size of the airflow field CFD calculation grid needs to be determined by comprehensively considering the accuracy of the gas phase field, the smoothness of time and space changes and the calculation consumption. Three different sizes of CFD grids were tested in the simulation and it was finally found that a computational domain containing 67.73 ten thousand CFD cells reached the best balance between accuracy and computational cost.
And step403, storing and analyzing simulation results and optimizing and reconstructing a flow field structure. The simulation results are shown in fig. 5. In the figure, the upper half part is a schematic section of the center of the equipment, and the air speed scale is contourr 1; the lower half part is a central section schematic diagram of a Laval nozzle, and the gas velocity scale is contourr 2.
Step5, auxiliary structure design: based on the simulation result of the airflow field (fig. 5), corresponding auxiliary equipment structures are designed, including but not limited to a complete machine support 3, a lifting platform 17, a lifting adjusting structure 14, a pneumatic executing structure 15, an actuator 13, a jet part supporting rod 16, a fixed hinge 5, a pipeline fastening ring 1, a proper flow balance valve 2, a soft connecting pipe 4 and a display control screen 11.
And step6, transformation implementation and application.
It is to be understood that the foregoing is only illustrative of the presently preferred embodiments of the invention and that the invention may be practiced using other techniques. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments illustrated herein, but is capable of various obvious modifications, rearrangements and substitutions without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
It is noted that in the description herein, references to the description of "some embodiments," "other embodiments," or the like, are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Claims (11)
1. A tobacco shred mass flow belt weigher calibration device is characterized by comprising a pipeline fastening ring, a flow balance valve, a whole machine bracket, a flexible connecting pipe, a fixed hinge, a gradually expanding cavity, a horizontal air distribution plate, a free flow cavity, a Laval nozzle, a display control screen, a connecting wire, an actuator, a lifting adjusting structure, a pneumatic execution structure, an injection part supporting rod, a lifting platform and a compressed air inlet connecting end;
the whole machine bracket is fixed above the conveying belt, the inner side of the pipeline fastening ring is wrapped with the compressed air inlet connecting end, and the outer side of the pipeline fastening ring is connected with the whole machine bracket;
one end of the compressed air inlet connecting end is connected with compressed air, and the other end of the compressed air inlet connecting end is connected with the flow balance valve;
the flow balance valve is connected with a soft connecting pipe, the lower side of the soft connecting pipe is connected with the gradually expanding cavity through a circular pipe, a horizontal air distribution plate is arranged at the tail end of the gradually expanding cavity, the lower end of the horizontal air distribution plate is connected with a free flow cavity, and the free flow cavity is connected with a Laval nozzle;
the lifting platform is arranged on one side of the whole machine support, the horizontal height of the lifting platform is adjusted through a lifting adjusting structure on the lifting platform, the display control screen is connected with the actuator through a connecting line, and the actuator controls the pneumatic execution structure to enable the cylinder of the pneumatic execution structure to contract or expand;
the air flow injection component and the lifting platform are respectively connected with the pneumatic execution structure through fixed hinges, and the injection component supporting rod is connected with the air flow injection component through the fixed hinges.
2. The tobacco shred mass flow belt scale calibrating device according to claim 1, wherein a cushion ring is arranged between the inner side of the pipeline fastening ring and the pipeline at the compressed air inlet connecting end so as to weaken the influence of vibration caused by the pneumatic execution structure action on the pipeline, and the inner diameter size of the pipeline fastening ring can be adjusted through a bolt fastener.
3. The tobacco shred mass flow belt scale calibrating device according to claim 1, wherein the flow balance valve adopts a pneumatic regulating valve to ensure the food safety requirement of the tobacco shreds as the food absorption product, and the flow precision of the flow balance valve is within 5%.
4. The tobacco shred mass flow belt scale calibrating device according to claim 1, wherein the gradually expanding cavity is of a regular quadrangular frustum pyramid structure, the upper bottom surface and the lower bottom surface are square, and the side length of the upper bottom surface is larger than the outer diameter of the connecting circular pipe; the side length of the lower bottom surface is 1.5 times larger than that of the upper bottom surface, and the height of the regular quadrangular frustum is not smaller than that of the upper bottom surface.
5. The tobacco shred mass flow belt weigher calibrating device according to claim 1, wherein the horizontal air distribution plate is a geometric structure in which round holes are uniformly formed in the horizontal plate, the ventilation degree of the horizontal air distribution plate is more than or equal to 50% so as to ensure that the throttling loss of the air distribution plate is within a reasonable range, the radius of the formed round holes is less than or equal to 8mm, and the number of the holes is set according to the ventilation degree.
6. The tobacco shred mass flow belt scale calibrating device according to claim 1, wherein the free flow cavity is a hollow cuboid structure, and the height of the free flow cavity is not less than the height of the gradually expanding cavity.
7. The tobacco shred mass flow belt weigher calibration device according to claim 1, wherein the front half part of the laval nozzle is contracted from big to small to the middle to a narrow throat, the narrow throat is expanded from small to big to the bottom, gas in the tube body flows into the front half part of the nozzle under high pressure, the gas flows out from the back half part after passing through the narrow throat, the gas flow generates an isentropic expansion process in the laval nozzle, the number of the laval nozzle is not less than 4, and the laval nozzle is axisymmetric and centrosymmetric with respect to the main flow direction of the gas flow in the circular tube.
8. The tobacco shred mass flow belt weigher calibrating device according to claim 1, wherein the geometry of the laval nozzle ensures that the isentropic flow velocity in the converging duct of the front half can only be continuously changed to mach number Ma-1, so that the air flow in the laval nozzle is from subsonic to sonic.
9. The tobacco shred mass flow belt scale calibration device according to claim 1, wherein the stroke of the cylinder piston of the pneumatic actuator enables the air jet part to rotate by not less than 60 °.
10. The tobacco shred mass flow belt scale calibrating device according to claim 1, wherein the actuator is provided with an emergency stop switch, and the air flow injection component can be retracted and the compressed air can be cut off at any time.
11. The tobacco shred mass flow belt scale calibrating device according to claim 1, wherein the lifting platform is installed at one side of the whole machine bracket through a lifting adjusting structure, and the adjusting range of the lifting adjusting structure is larger than 10 cm.
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