CN115355972A - Weightless metering method and device applied to weighing of powder materials - Google Patents
Weightless metering method and device applied to weighing of powder materials Download PDFInfo
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- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
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Abstract
The invention discloses a weightless metering method and a weightless metering device applied to weighing powder materials, which are characterized in that each device in a production process is in an initial state through initialization control, then material is supplemented to a metering bin according to the current material quantity condition in the metering bin, then the instantaneous powder quantity at each time point in the metering bin in a unit time period is weighed, and an average value is taken, so that the feeding speed of a spiral feeding device is controlled in real time, and the powder quantity sent to the next production device is adjusted; the device for weightless metering of powder by adopting the method comprises a material receiving bin, a metering bin, a spiral feeding device and a control system; the material receiving bin is arranged above the metering bin; the metering bin is arranged below the spiral feeding device; the spiral feeding device is connected with the next process equipment. By the method and the equipment, the powder which generates large fluctuation can be accurately and stably weighed, the feeding speed of the equipment is adjusted in real time according to the weighing condition, and the accuracy of the powder in the using process is ensured.
Description
Technical Field
The invention belongs to the technical field of automatic control, and particularly relates to a weight-loss metering method and a weight-loss metering device applied to weighing of powder materials.
Background
The powder material is called powder for short and comprises metal powder material, chemical product powder, plastic powder particles and the like. The powder is widely applied to the industrial production fields of metal smelting, chemical production, concrete production, modern plastic manufacturing and forming industry and the like. In the using process of the powder, the input amount needs to be determined through accurate weighing so as to achieve the purposes of saving cost, accurately configuring the component content of the material and the like, so that the weighing of the powder is an important process link in industrial production. In present powder material measurement weighing-appliance, weightlessness type metering device can obtain better weighing effect when low material volume, but when making the instantaneous material volume produce great fluctuation change under the circumstances such as drop into more powder, especially in the better powder material instantaneous change weighing control of mobility, current metering device can't stabilize accurate measurement to the powder material, make the deviation appears with the material volume of settlement in the powder material volume of final input equipment, influence the component proportion, bring unnecessary waste, the in-service use condition is relatively poor.
Disclosure of Invention
The invention aims to provide a weight-loss metering method and a weight-loss metering device applied to weighing of powder materials, aiming at the defects in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a weight loss type metering method applied to weighing of powder materials comprises the following steps:
the method comprises the following steps: equipment initialization control; the powder enters a material receiving bin through a material pipeline; the powder metering device is started in an automatic control mode, and equipment is initialized to be in an initial state;
step two: controlling the material supplementing before metering; after the initialization of the powder metering device is finished, the control system checks the weight of materials in the metering bin through the powder metering device, if the weight of the materials is lower than the median line of a material metering interval of the metering bin, material supplementing is started, a material supplementing dome valve and a pressure release valve are opened, a fluidizing valve is intermittently opened, and powder enters the metering bin through a material supplementing pipeline until the weight of the metering bin is larger than the upper limit of the metering interval of the metering bin, so that the condition that the instantaneous material quantity fluctuation is large due to insufficient adjusting time before material supplementing in the next period is avoided, and the period is called a material pre-supplementing period; if the weight of the material is more than or equal to the middle line of the material metering interval of the metering bin after the initialization is finished, skipping a pre-feeding period;
middle line WT between material metering intervals of metering bin during pre-feeding period MID The calculation is as follows:
WT MID : a material metering interval middle line of the metering bin;
WT LOW : the lower limit of a metering interval of the metering bin;
WT UP : the upper limit of a metering interval of the metering bin;
step three: metering start control; when the equipment initialization is completed and the weight of the materials in the metering bin meets the requirement of a middle line in a metering interval of the materials in the metering bin or is more than or equal to the weight of the materials in the metering bin, or the pre-feeding period is finished, the metering is started, and all the parts of the device are switched to the equipment state in the metering period; the method comprises the following steps that a material quantity regulation PID keeps a manual mode, a frequency converter of a spiral feeding device is started according to starting frequency, after the frequency converter is started for 5s, the material quantity regulation PID is switched to an automatic mode, instantaneous material quantity is used as a feedback value, the frequency set value of the frequency converter of the spiral feeding device is regulated from an initial set value during starting, and fixed regulation quantity and the minimum value of the absolute value of the deviation between the current set value and a target set value are used as actual regulation quantity to be increased or decreased until the material quantity is set; the instantaneous material amount is obtained by calculating the reduction amount of the weight of the metering bin and is stably regulated, and the period is called as a starting period;
the instantaneous material amount WI is obtained by differential calculation from the weight change of the metering bin, and the calculation formula is as follows:
WI: instantaneous material quantity;
WT t+Δt : measuring the weight of the bin at the time t + delta t;
WT t : measuring the weight of the bin at the time t;
Δ t: a time interval.
Initial set value WI _ SP when material quantity regulation PID starts 0 According to the maximum value setting of the instantaneous material quantity when the frequency converter of the spiral feeding device is at the starting frequency and the maximum value setting of the instantaneous material quantity in the 5% measuring range of the powder metering device, the calculation formula is as follows:
WI_SP 0 ＝MAX(WI FREQ0 ，WI Range ×5)
WI Range ＝WI MAX -WI MIN
WI_SP 0 : adjusting an initial set value when the PID is started according to the material quantity;
WI FREQ0 : instantaneous material quantity when a frequency converter of the spiral feeding device is at starting frequency;
WI Range : the range of the device;
WI MAX : the upper limit of the measuring range of the device;
WI MIN : the lower limit of the range of the present device is usually 0.
The fixed regulating quantity of the material quantity regulating PID set value is determined according to 2% of the design range of the powder metering device, the actual regulating quantity is determined according to the minimum value of the fixed regulating quantity and the target deviation quantity, and the calculation formula is as follows:
ΔSP＝WI Range ×2％
ΔWI_SP＝MIN(|WI_SP current -WI_SP target |，ΔSP)
Δ SP: the fixed regulating quantity of the material quantity regulating PID setting value;
Δ WI _ SP: adjusting the actual adjustment quantity of a PID setting value of the material quantity;
WI_SP current : adjusting the current set value of PID according to the material quantity;
WI_SP target : and adjusting PID target set values according to the material quantity.
Step four: detecting and automatically controlling the flow of the powder material according to the set material flow; the material quantity regulation PID of the powder metering device keeps an automatic mode and automatically regulates according to the set material quantity; when the set material quantity changes, the material quantity adjusting PID set value is increased or decreased according to the fixed adjusting quantity until the set material quantity is reached, and the material quantity is stably adjusted; taking a point at the early stage and the final stage of the period respectively to calculate the relationship between the actual set frequency of the frequency converter and the set material quantity and the weight of the metering bin, and obtaining a correction coefficient; this period is referred to as the metering period;
under the same weight of the metering bin, the higher the set material quantity is, the higher the frequency of the frequency converter needs to be set, and the set frequency and the set material quantity are in a direct proportion relation in an ideal state; in the actual use process, because the mobility of powder material, the big mobility is stronger when the dead weight of material is big, consequently under the same settlement material volume, measurement storehouse material weight is heavier, and the frequency converter needs the frequency of setting then less, and the frequency of setting is approximately in inverse relation with measurement storehouse weight, therefore has following relation between the three:
FREQ SP : setting the frequency of a frequency converter;
k: correction factor
WI _ SP: adjusting the set value of PID according to the material quantity;
WT: and (5) measuring the weight of the materials in the bin.
A: constant number
In the metering process of the powder metering device, the frequency set value FREQ of the frequency converter at the t2 second after the completion of the material supplement is taken SP-t2 And the set value WI _ SP of the material quantity regulation PID t2 Material weight WT of measuring bin t2 And the frequency set value FREQ of the frequency converter at the end of the metering period SP-End And the set value WI _ SP of the material quantity regulation PID End And the weight WT of the materials in the measuring bin End The correction coefficient K can be found, namely:
step five: detecting and controlling the weight of the material in the measuring bin; according to the method, the weight of the materials in the metering bin is detected in real time, and when the weight of the metering bin is smaller than the lower limit of the metering interval of the metering bin, material supplementing is started until the weight of the metering bin is larger than the upper limit of the metering interval of the metering bin, and the material supplementing is finished; this period is called the feed period;
step six: the material flow is automatically fed forward and controlled during the material supplementing period of the metering bin and the stabilizing period after material supplementing; after the material supplementing of the metering bin is finished, a certain time is needed for the closing of a material supplementing valve and the material to be stable, and a stable period of fixed time t1 is set after the material supplementing is finished; during the material supplementing period and the stabilizing period, the frequency PID adjusting function block of the frequency converter is switched to a manual mode, proportion adjustment is directly carried out according to the correction coefficient K, and after the stabilizing period is finished, the program automatically enters the metering period and is controlled according to the fourth step;
during the feeding period and the stable period, the frequency set value of the frequency converter is calculated according to the following formula, and the calculation results of the two formulas are the same:
or:
step seven: metering stop control; when the powder metering device stops, all the equipment and the control module return to initial positions; this period is referred to as a stop period;
step eight: in the seventh step, when the powder metering device needs to empty the metering bin due to maintenance and other reasons, a bin cleaning command can be issued through local or remote control, then feeding is not executed when the weight of the material in the metering bin is less than the lower limit of the metering interval of the metering bin, and control is continued according to the metering period until the weight of the metering bin approaches to 0; this period is called the purge period.
Step nine: in step eight, when a major fault such as emergency stop occurs in the powder metering device, the stop command is immediately executed unconditionally, all the equipment and the control module return to the initial position, and the equipment is checked.
As a further technical improvement, the initial state in the step one comprises that all valves execute a closing command, all electrical equipment executes a stopping command, and the material quantity regulation PID is switched to a manual mode; after an initial state command is sent for 10s, checking whether all valves are in a closed state, whether all electrical equipment are in a stop state, and the state of a material weight measuring point of the metering bin is normal, otherwise, initializing, and forbidding starting when the initialization fails; this period is referred to as the initialization period.
As a further technical improvement, the equipment state in the metering period in the third step comprises that an exhaust valve is opened, a feeding dome valve, a pressure release valve and a fluidizing valve are closed, a spiral feeding device and a scattering device are started, and a material quantity regulation PID is kept in a manual mode.
As a further technical improvement, the major faults described in the ninth step include on-site and local or remote emergency stop button activation, screw feeder failure, when WI-WI _ SP ≧ MAX (WI _ SP × 20%, WI) Range X 10%) over 20s, the weight of material in metering bin shows failure, the weight of material in metering bin is higher than the highest upper limit, the weight of material in metering bin is lower than the lowest lower limit and is not in the period of cleaning bin, and the material is supplementedThe dome valve is closed overtime fault, the feeding overtime fault and other faults which influence the stability and the accurate operation of the powder metering device. When WI-WI _ SP is greater than or equal to MAX (WI _ SP multiplied by 20%, WI) Range X 10%) over 20s, the material quantity deviation is large, and the judgement value and judgement delay time in actual use can be regulated according to the real condition.
As a further technical improvement, the device applied to the weightless metering method for weighing the powder material comprises a material receiving bin, a metering bin, a spiral feeding device and a control system; the material receiving bin is arranged above the metering bin; the top of the material receiving bin is connected with a material pipeline, and the bottom of the material receiving bin is provided with a material supplementing pipeline connected with the metering bin; a feeding valve is arranged on the feeding pipeline; a powder metering device is arranged in the metering bin; the spiral feeding device is arranged at the bottom of the metering bin and is connected with the next process equipment. The material receiving bin is used for temporarily storing powder; the material pipeline leads the material into the material receiving bin; the material supplementing pipeline is used for introducing powder in the material receiving bin into the metering bin; the powder metering device is a powder weighing device; the spiral feeding device can convey powder from the metering bin to next process equipment; the metering bin is a weighing bin commonly used in the industry.
As a further technical improvement, the lower part of the material receiving bin is provided with a dredging pipe; the dredging pipe is connected with an air source; the part of the dredging pipe positioned in the material receiving bin is provided with a dredging air hole; and a dredging air valve is arranged on the dredging pipe. The origin is already a low pressure gas reservoir; the gas introduced into the dredging pipe can be dry air or nitrogen; gas is discharged through the air holes to impact powder, so that the effect of dredging is achieved, and the blockage of the outlet of the material receiving bin is avoided.
As a further technical improvement, the bottom of the metering bin is provided with a discharging barrel; the discharging barrel is provided with a scattering device; the scattering device comprises a scattering stirring rod extending into the discharge barrel and a scattering motor for driving the scattering stirring rod; the scattering motor is arranged outside the discharging barrel. The scattering motor drives the scattering stirring rod to rotate, the powder in the discharge cylinder is scattered, and the powder is prevented from being caked and blocked.
As a further technical improvement, an exhaust pipe is also arranged on the metering bin; the material receiving bin is also provided with a pressure relief pipe; the pressure relief pipe is communicated with the exhaust pipe; an exhaust valve is arranged on the exhaust pipe; and a pressure relief valve is arranged on the pressure relief pipe. The feeding valve, the dredging valve and the exhaust valve are all electric valves or pneumatic valves.
As a further technical improvement, the control system comprises a local control system and a remote control system; the local control system is a control cabinet established based on a PLC; the remote control system is connected with the production line through a network so as to produce equipment; the local control system and the remote control system are both provided with a manual control mode and an automatic control mode. The local control system is used for emergency stop and debugging and test run of the field equipment; the remote control system is used for centralized production control, can be started and stopped by an operator in a remote control mode, and monitors equipment.
The technical scheme of the invention has the following beneficial effects:
1. the invention calculates the instantaneous powder amount of each time point in the measuring bin in a unit time period through the calculus, then obtains an average value, and controls the feeding speed of the spiral feeding device in real time through the powder weight change relation of the measuring bin, adjusts the powder amount sent to the next production equipment, and avoids the influence on the feeding speed of the equipment caused by overlarge instantaneous powder weight change fluctuation.
2. According to the invention, before powder weighing and feeding, all equipment devices are initialized to the initial state, and corresponding valves and switches are closed, so that all parts of equipment start to run from the initial state in the running process of the device, the equipment can be ensured to run in a matching way, and faults are avoided.
3. The invention checks whether each part of the device is in normal state before running, and the equipment can run only after checking, thereby ensuring that the equipment is normal when running.
4. According to the invention, after a fault occurs in the operation process of the equipment, all devices are synchronously stopped, so that the damage to the equipment caused by the fault operation in the process step is avoided.
5. The device provided by the invention intermittently blows air through the dredging pipe, so that powder blockage at the outlet of the material receiving bin can be avoided, powder agglomeration can be avoided through the scattering device, and the discharge of the discharge barrel at the bottom of the metering bin is smoother.
Drawings
FIG. 1 is a schematic flow diagram of the process of the present invention.
FIG. 2 is a schematic diagram of the structure of an apparatus for carrying out the method of the present invention.
Reference numerals: 1-a material receiving bin, 2-a metering bin, 3-a spiral feeding device, 4-a material pipeline, 5-a material supplementing pipeline, 6-a material supplementing valve, 7-a powder metering device, 8-a discharging barrel, 9-a scattering device, 10-a dredging pipe, 11-a dredging air valve, 12-an exhaust pipe, 13-an exhaust valve, 14-a pressure relief pipe and 15-a pressure relief valve.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
Example 1:
as shown in fig. 1-2, a weight loss type metering method applied to weighing of powder materials comprises the following steps:
the method comprises the following steps: equipment initialization control; powder enters the material receiving bin 1 through the material pipeline 4; the powder metering device 7 is started in an automatic control mode, and equipment is initialized to be in an initial state;
step two: controlling the material supplement before metering; after the initialization of the powder metering device 7 is finished, the control system checks the weight of materials in the metering bin 2 through the powder metering device 7, if the weight of the materials is lower than the median line of the material metering interval of the metering bin 2, material supplementing is started, the material supplementing dome valve and the pressure release valve 15 are opened, the fluidizing valve is intermittently opened, the powder enters the metering bin 2 through the material supplementing pipeline 5 until the weight of the metering bin 2 is larger than the upper limit of the metering interval of the metering bin 2, the condition that the instantaneous material fluctuation is large due to insufficient adjusting time before material supplementing in the next period is avoided, and the period is called a material pre-supplementing period; if the weight of the material is more than or equal to the middle line of the material metering interval of the metering bin 2 after the initialization is finished, skipping a pre-feeding period;
material metering interval neutral line WT of metering bin 2 during pre-feeding period MID The calculation is as follows:
WT MID : a material metering interval middle line of the metering bin 2;
WT LOW : the lower limit of the metering interval of the metering bin 2;
WT UP : the upper limit of the metering interval of the metering bin 2;
step three: metering start control; when the initialization of the equipment is completed and the weight of the materials in the metering bin 2 meets the requirement of a middle line in a material metering interval of the metering bin 2 or is more than or equal to the requirement of the middle line or the end of a pre-feeding period, the metering is started, and each device part is switched to a metering period equipment state; the material quantity regulation PID keeps a manual mode, a frequency converter of the spiral feeding device 3 is started according to the starting frequency, after the starting for 5s, the material quantity regulation PID is switched to an automatic mode, the instantaneous material quantity is taken as a feedback value, the frequency set value of the frequency converter of the spiral feeding device 3 is regulated from the initial set value during the starting, and the fixed regulation quantity and the minimum value of the absolute value of the deviation between the current set value and the target set value are taken as actual regulation quantities to be increased or decreased until the material quantity is set; the instantaneous material amount is obtained by calculating the reduction amount of the weight of the metering bin 2 and is stably regulated, and the period is called as a starting period;
the instantaneous material amount WI is obtained by differential calculation from the weight change of the metering bin 2, and the calculation formula is as follows:
WI: instantaneous material quantity;
WT t+Δt : measuring the weight of the bin 2 at the time of t + delta t;
WT t : measuring the weight of the bin 2 at the moment t;
Δ t: a time interval.
Initial set value WI _ SP when material quantity regulation PID starts 0 According to the maximum value setting of the instantaneous material quantity when the frequency converter of the spiral feeding device 3 is at the starting frequency and the maximum value setting of the instantaneous material quantity in 5 percent of the measuring range of the powder metering device 7, calculatingThe formula is as follows:
WI_SP 0 ＝MAX(WI FREQ0 ，WI Range ×5％)
WI Range ＝WI MAX -WI MIN
WI_SP 0 : adjusting an initial set value when the PID is started according to the material quantity;
WI FREQ0 : the instantaneous material quantity of the frequency converter of the spiral feeding device 3 at the starting frequency;
WI Range : the range of the device;
WI MAX : the upper limit of the measuring range of the device;
WI MIN : the lower limit of the range of the present device is usually 0.
The fixed regulating quantity of the material quantity regulating PID setting value can be determined according to real adjustment according to 2% of the design range of the powder metering device 7, the actual regulating quantity is determined according to the minimum value of the fixed regulating quantity and the target deviation quantity, and the calculation formula is as follows:
ΔSP＝WI Range ×2％
ΔWI_SP＝MIN(|WI_SP current -WI_SP target |，ΔSP)
Δ SP: the fixed regulating quantity of the material quantity regulating PID setting value;
Δ WI _ SP: the actual regulating quantity of the material quantity regulating PID setting value;
WI_SP current : adjusting the current set value of PID according to the material quantity;
WI_SP target : and adjusting the PID target set value according to the material quantity.
Step four: detecting and automatically controlling the flow of the powder material according to the set material flow; the material quantity adjusting PID of the powder metering device 7 keeps an automatic mode and automatically adjusts according to the set material quantity; when the set material quantity changes, the material quantity regulation PID set value is increased or decreased according to the fixed regulation quantity until the set material quantity is set and is stably regulated; taking a point at each of the early stage and the final stage of the period to calculate the relationship between the actual set frequency of the frequency converter and the set material quantity and the weight of the measuring bin 2, and obtaining a correction coefficient; this period is referred to as the metering period;
under the same weight of the metering bin 2, the higher the set material quantity is, the higher the frequency of the frequency converter needs to be set, and the set frequency and the set material quantity are in a direct proportion relation in an ideal state; in the practical use process, because the mobility of powder material, the bigger the dead weight of material is, the stronger the mobility is, therefore under the same set material volume, the heavier the material weight of the measuring bin 2 is, the smaller the frequency converter needs to be set, the set frequency is approximately in inverse proportion with the weight of the measuring bin 2, so the following relation exists between the three:
FREQ SP : setting the frequency of a frequency converter;
k: correction factor
WI _ SP: adjusting the set value of PID according to the material quantity;
WT: and (4) measuring the weight of the materials in the bin 2.
A: constant number
In the metering process of the powder metering device 7, the frequency set value FREQ of the frequency converter at the t2 second after the completion of material supplement is taken SP-t2 And the set value WI _ SP of the material quantity regulation PID t2 2 measuring bin 2 material weight WT t2 And the frequency set value FREQ of the frequency converter at the end of the metering period SP-End And the set value WI _ SP of the material quantity regulation PID End 2 measuring bin 2 material weight WT End The correction coefficient K can be found, namely:
step five: detecting and controlling the weight of the material in the measuring bin 2; according to the method, the weight of the material in the metering bin 2 is detected in real time, when the weight of the metering bin 2 is smaller than the lower limit of the metering interval of the metering bin 2, material supplement is started until the weight of the metering bin 2 is larger than the upper limit of the metering interval of the metering bin 2, and the material supplement is finished; this period is called the feed period;
step six: the material flow is automatically fed forward and controlled in the material supplementing period and the post-material supplementing stable period of the metering bin 2; after the material feeding of the metering bin 2 is finished, because the closing of the material feeding valve 6 has time delay and the material needs a certain time for stabilization, a fixed time t1t1< t2-15s is set after the material feeding is finished, and t2 is a stable period of sampling time when the correction coefficient K is calculated during the metering period; during the material supplementing period and the stabilizing period, the frequency PID adjusting function block of the frequency converter is switched to a manual mode, proportion adjustment is directly carried out according to the correction coefficient K, and after the stabilizing period is finished, the program automatically enters the metering period and is controlled according to the fourth step;
during the feeding period and the stable period, the frequency set value of the frequency converter is calculated according to the following formula (the calculation results of the two formulas are the same):
or:
step seven: metering stop control; when the powder metering device 7 stops, all the equipment and the control modules return to initial positions; this period is referred to as a stop period;
step eight: in the seventh step, when the powder metering device 7 needs to empty the metering bin 2 due to reasons such as maintenance and the like, a bin cleaning command can be issued through local or remote control, then feeding is not executed when the weight of the materials in the metering bin 2 is less than the lower limit of the metering interval of the metering bin 2, and control is continued according to the metering period until the weight of the metering bin 2 approaches to 0; this period is called the purge period.
Step nine: in step eight, when a major fault such as an emergency stop occurs in the powder metering device 7, the stop command is executed unconditionally immediately, all the equipment and the control module return to the initial position, and the equipment is checked.
The initial state in the first step comprises that all valves execute closing commands, all electrical equipment execute stop commands, and the material quantity regulation PID is switched to a manual mode; after an initial state command is sent for 10s, checking whether all valves are in a closed state, whether all electrical equipment are in a stop state, and the state of the material weight measuring point of the metering bin 2 is normal, otherwise, initializing fails, and starting is forbidden when the initialization fails; this period is referred to as the initialization period.
And in the third step, the equipment state in the metering period comprises that an exhaust valve 13 is opened, a feeding dome valve, a pressure release valve 15 and a fluidizing valve are closed, a spiral feeding device 3 and a scattering device 9 are started, and a material quantity regulation PID keeps a manual mode.
The major faults in the step nine comprise the activation of a field and local or remote emergency stop button, the fault of the spiral feeding device 3, and when the WI-WI _ SP is more than or equal to MAX (WI _ SP multiplied by 20 percent, WI) Range X 10%) over 20s, the weight of the material in the metering bin 2 shows a fault, the weight of the material in the metering bin 2 is higher than the highest upper limit, the weight of the material in the metering bin 2 is lower than the lowest lower limit and is not in the clearing period, the feeding dome valve is closed overtime fault, the feeding overtime fault and other faults which influence the stable and accurate operation of the powder metering device 7.
The device applied to the weightless metering method for weighing the powder material comprises the following steps: comprises a material receiving bin 1, a metering bin 2, a spiral feeding device 3 and a control system; the material receiving bin 1 is arranged above the metering bin 2; the top of the material receiving bin 1 is connected with a material pipeline 4, and the bottom of the material receiving bin is provided with a material supplementing pipeline 5 connected with the metering bin 2; a feeding valve 6 is arranged on the feeding pipeline 5; a powder metering device 7 is arranged in the metering bin 2; the spiral feeding device 3 is arranged at the bottom of the metering bin 2 and is connected with the next process equipment.
The lower part of the material receiving bin 1 is provided with a dredging pipe 10; the dredging pipe 10 is connected with an air source; the part of the dredging pipe 10 positioned in the material receiving bin 1 is provided with a dredging air hole; the dredging pipe 10 is provided with a dredging air valve 11.
The control system comprises a local control system and a remote control system; the local control system is a control cabinet established based on a PLC; the remote control system is connected with the production line through a network so as to produce equipment; and the local control system and the remote control system are both provided with a manual control mode and an automatic control mode.
Example 2:
this example differs from example 1 in that: the bottom of the metering bin 2 is provided with a discharging barrel 8; the discharging barrel 8 is provided with a scattering device 9; the breaking device 9 comprises a breaking stirring rod extending into the discharge barrel 8 and a breaking motor for driving the breaking stirring rod; the scattering motor is arranged outside the discharging barrel 8.
The method of use of this example is the same as example 1.
Example 3:
the present example differs from example 2 in that: the metering bin 2 is also provided with an exhaust pipe 12; the material receiving bin is also provided with a pressure relief pipe 14; the pressure relief pipe 14 is communicated with the exhaust pipe 12; an exhaust valve 13 is arranged on the exhaust pipe 12; and a pressure relief valve 15 is arranged on the pressure relief pipe 14.
The method of use of this example is the same as example 1.
Example 4:
this example differs from example 3 in that: the bottom of the metering bin 2 is provided with a discharging barrel 8; the discharging barrel 8 is provided with a scattering device 9; the scattering device 9 comprises a scattering stirring rod extending into the discharging barrel 8 and a scattering motor for driving the scattering stirring rod; the scattering motor is arranged outside the discharging barrel 8. An exhaust pipe 12 is also arranged on the metering bin 2; the material receiving bin is also provided with a pressure relief pipe 14; the pressure relief pipe 14 is communicated with the exhaust pipe 12; an exhaust valve 13 is arranged on the exhaust pipe 12; a pressure relief valve 15 is arranged on the pressure relief pipe 14.
The method of use of this example is the same as example 1.
The above embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and the scope of the present invention is defined by the claims. Various modifications and equivalents of the invention may be made by those skilled in the art within the spirit and scope of the invention, and such modifications and equivalents should also be considered as falling within the scope of the invention.
Claims (9)
1. A weightlessness type metering method applied to weighing of powder materials is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: equipment initialization control; powder enters the material receiving bin (1) through a material pipeline (4); the powder metering device (7) is started in an automatic control mode, and equipment is initialized to be in an initial state;
step two: controlling the material supplementing before metering; after the initialization of the powder metering device (7) is finished, the control system checks the weight of the materials in the metering bin (2) through the powder metering device (7), if the weight of the materials is lower than the median line of the material metering interval of the metering bin (2), the material supplementing is started, a material supplementing dome valve and a pressure release valve (15) are opened, a fluidizing valve is intermittently opened, the powder enters the metering bin (2) through a material supplementing pipeline (5) until the weight of the metering bin (2) is larger than the upper limit of the metering interval of the metering bin (2), the phenomenon that the instantaneous material quantity fluctuates greatly due to insufficient adjusting time before material supplementing in the next period is avoided, and the period is called a pre-material supplementing period; if the weight of the material is more than or equal to the middle line of the material metering interval of the metering bin (2) after the initialization is finished, skipping a pre-feeding period;
the middle line WT of the material metering interval of the metering bin (2) during the pre-feeding period MID The calculation is as follows:
WT MID : the material metering section middle line of the metering bin (2);
WT LOW : the lower limit of the metering interval of the metering bin (2);
WT UP : the upper limit of a metering interval of the metering bin (2);
step three: metering starting control; when the equipment initialization is completed and the weight of the materials in the metering bin (2) meets the requirement of a median line in a material metering interval of the metering bin (2) or is equal to or more than the requirement of the median line or the end of a pre-feeding period, the metering is started, and each device part is switched to a metering period equipment state; the material quantity regulation PID keeps a manual mode, a frequency converter of the spiral feeding device (3) is started according to the starting frequency, after the frequency converter is started for 5s, the material quantity regulation PID is switched to an automatic mode, the instantaneous material quantity is taken as a feedback value, the frequency set value of the frequency converter of the spiral feeding device (3) is regulated from the initial set value during starting, and the fixed regulation quantity and the minimum value of the absolute value of the deviation between the current set value and the target set value are taken as actual regulation quantities to be increased or decreased until the material quantity is set; the instantaneous material amount is obtained by calculating the reduction amount of the weight of the metering bin (2) and is stably regulated, and the period is called as a starting period;
the instantaneous material amount WI is obtained by differentiating the weight change of the metering bin (2), and the calculation formula is as follows:
WI: instantaneous material quantity;
WT t+Δt : the weight of the bin (2) is measured at the time of t + delta t;
WT t : the weight of the bin (2) is measured at the moment t;
Δ t: a time interval.
Initial set value WI _ SP when material quantity regulation PID starts 0 According to the maximum value setting of the instantaneous material quantity when the frequency converter of the spiral feeding device (3) is at the starting frequency and the maximum value setting of the instantaneous material quantity in 5% of the measuring range of the powder metering device (7), the calculation formula is as follows:
WI_SP 0 ＝MAX(WI FREQ0 ，WI Range ×5％)
WI Range ＝WI MAX -WI MIN
WI_SP 0 : adjusting an initial set value when the PID is started according to the material quantity;
WI FREQ0 : the instantaneous material quantity of a frequency converter of the spiral feeding device (3) is at the starting frequency;
WI Range : the range of the device;
WI MAX : the upper limit of the measuring range of the device;
WI MIN : the lower limit of the range of the present device is usually 0.
The fixed regulating quantity of the material quantity regulating PID setting value is determined according to 2 percent (which can be adjusted according to real) of the design range of the powder metering device (7), the actual regulating quantity is determined according to the minimum value of the fixed regulating quantity and the target deviation quantity, and the calculation formula is as follows:
ΔSP＝WI Range ×2％
ΔWI_SP＝MIN(|WI_SP current -WI_SP target |，ΔSP)
Δ SP: the fixed regulating quantity of the material quantity regulating PID setting value;
Δ WI _ SP: adjusting the actual adjustment quantity of a PID setting value of the material quantity;
WI_SP current : adjusting the current set value of PID (proportion integration differentiation) by the material quantity;
WI_SP target : and adjusting PID target set values according to the material quantity.
Step four: detecting and automatically controlling the flow of the powder material according to the set material flow; the material quantity regulation PID of the powder metering device (7) keeps an automatic mode and automatically regulates according to the set material quantity; when the set material quantity changes, the material quantity adjusting PID set value is increased or decreased according to the fixed adjusting quantity until the set material quantity is reached, and the material quantity is stably adjusted; taking a point at each of the early stage and the final stage of the period to calculate the relationship between the actual set frequency of the frequency converter and the set material quantity and the weight of the metering bin (2) so as to obtain a correction coefficient; this period is referred to as the metering period;
under the same weight of the metering bin (2), the higher the set material quantity is, the higher the frequency setting frequency of the frequency converter needs to be, and the set frequency and the set material quantity are in a direct proportion relation in an ideal state; in the actual use process, because the fluidity of the powder material is stronger when the self weight of the material is larger, under the same set material amount, the weight of the material in the metering bin (2) is heavier, the frequency which needs to be set by the frequency converter is smaller, the set frequency is approximately in inverse proportion to the weight of the metering bin (2), and therefore the three materials have the following relations:
FREQ SP : setting the frequency of a frequency converter;
k: correction factor
WI _ SP: adjusting the set value of PID according to the material quantity;
WT: and the weight of the materials in the metering bin (2).
A: constant number
In the metering process of the powder metering device (7), the first time after the material taking and supplementing is finishedFrequency set value FREQ of frequency converter at t2 seconds SP-t2 And the set value WI _ SP of the material quantity regulation PID t2 Material weight WT of measuring bin (2) t2 And a frequency set value FREQ of the frequency converter at the end of the metering period SP-End And a set value WI _ SP of the material quantity regulation PID End Material weight WT of measuring bin (2) End The correction coefficient K can be found, namely:
step five: detecting and controlling the weight of the material in the measuring bin (2); according to the method, the weight of the material in the metering bin (2) is detected in real time, and when the weight of the metering bin (2) is smaller than the lower limit of the metering interval of the metering bin (2), material supplement is started until the weight of the metering bin (2) is larger than the upper limit of the metering interval of the metering bin (2), and the material supplement is finished; this period is called the feed phase;
step six: the metering bin (2) automatically controls the material flow in a feed-forward manner during the feed supplement period and during the stabilization period after the feed supplement; after the material feeding of the metering bin (2) is finished, because the closing of the material feeding valve (6) has time delay and a certain time is needed for material stabilization, a stabilization period of a fixed time t1 (t 1< t2-15s, t2 is the sampling time when the metering period calculates the correction coefficient K) is set after the material feeding is finished; during the material supplementing period and the stabilizing period, the frequency PID adjusting function block of the frequency converter is switched to a manual mode, proportion adjustment is directly carried out according to the correction coefficient K, and after the stabilizing period is finished, the program automatically enters the metering period and is controlled according to the fourth step;
during the feeding period and the stable period, the frequency set value of the frequency converter is calculated according to the following formula, and the calculation results of the two formulas are the same:
or:
step seven: metering stop control; when the powder metering device (7) stops, all the equipment and the control module return to the initial position; this period is referred to as a stop period;
step eight: in the seventh step, when the metering bin (2) needs to be emptied by the powder metering device (7) due to reasons such as maintenance and the like, a bin-clearing command can be issued through local or remote control, then feeding is not executed when the weight of the materials in the metering bin (2) is less than the lower limit of the metering interval of the metering bin (2), and control is continued according to the metering period until the weight of the metering bin (2) is close to 0; this period is called the purge period.
Step nine: in step eight, when a serious fault such as emergency stop occurs in the powder metering device (7), a stop command is immediately executed unconditionally, all equipment and control modules return to the initial position, and the equipment is checked.
2. The weight loss type metering method applied to powder material weighing according to claim 1, characterized in that: the initial state in the first step comprises that all valves execute a closing command, all electrical equipment execute a stopping command, and the material quantity regulation PID is switched to a manual mode; after an initial state command is sent for 10s, checking whether all valves are in a closed state, whether all electrical equipment are in a stop state, and the state of the material weight measuring point of the metering bin (2) is normal, otherwise, initializing fails, and starting is forbidden when the initialization fails; this period is referred to as the initialization period.
3. The weight loss type metering method applied to powder material weighing according to claim 1, characterized in that: and in the third step, the equipment state in the metering period comprises that an exhaust valve (13) is opened, a feeding dome valve, a pressure release valve (15) and a fluidizing valve are closed, a spiral feeding device (3) and a scattering device (9) are started, and a material quantity regulation PID keeps a manual mode.
4. The weight loss type metering method applied to powder material weighing according to claim 1, characterized in that: major faults described in step nine includeActivation of emergency stop button in field, local or remote, failure of screw feeder (3), when WI-WI _ SP is greater than or equal to MAX (WI _ SP x 20%, WI) Range X 10%) is more than 20s, the material weight of the metering bin (2) shows a fault, the material weight of the metering bin (2) is higher than the highest upper limit, the material weight of the metering bin (2) is lower than the lowest lower limit and is not in the clearing period, the feeding dome valve is closed overtime fault, the feeding overtime fault and other faults which influence the stable and accurate operation of the powder metering device (7).
5. A device adopting the weight loss type metering method applied to powder material weighing according to any one of claims 1 to 4, which is characterized in that: comprises a material receiving bin (1), a metering bin (2), a spiral feeding device (3) and a control system; the material receiving bin (1) is arranged above the metering bin (2); the top of the material receiving bin (1) is connected with a material pipeline (4), and the bottom of the material receiving bin is provided with a material supplementing pipeline (5) connected with the metering bin (2); a material supplementing valve (6) is arranged on the material supplementing pipeline (5); a powder metering device (7) is arranged in the metering bin (2); the spiral feeding device (3) is arranged at the bottom of the metering bin (2) and is connected with the next process equipment.
6. The device applied to the weightless metering method for weighing the powder material as claimed in claim 5, wherein: a dredging pipe (10) is arranged at the lower part of the material receiving bin (1); the dredging pipe (10) is connected with an air source; the part of the dredging pipe (10) positioned in the material receiving bin (1) is provided with a dredging air hole; and a dredging air valve (11) is arranged on the dredging pipe (10).
7. The device applied to the weightless metering method for weighing the powder material as claimed in claim 5, wherein: a discharge barrel (8) is arranged at the bottom of the metering bin (2); a scattering device (9) is arranged on the discharging barrel (8); the scattering device (9) comprises a scattering stirring rod extending into the discharging barrel (8) and a scattering motor for driving the scattering stirring rod; the breaking motor is arranged outside the discharge barrel (8).
8. The device applied to the weight-loss metering method for weighing the powder material as claimed in claim 5, wherein the device comprises: the metering bin (2) is also provided with an exhaust pipe (12); the material receiving bin is also provided with a pressure relief pipe (14); the pressure relief pipe (14) is communicated with the exhaust pipe (12); an exhaust valve (13) is arranged on the exhaust pipe (12); and a pressure relief valve (15) is arranged on the pressure relief pipe (14).
9. The device applied to the weight-loss metering method for weighing the powder material as claimed in claim 5, wherein the device comprises: the control system comprises a local control system and a remote control system; the local control system is a control cabinet established based on a PLC; the remote control system is connected with the production line through a network so as to produce equipment; the local control system and the remote control system are both provided with a manual control mode and an automatic control mode.
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| CN202210917164.5A CN115355972A (en) | 2022-08-01 | 2022-08-01 | Weightless metering method and device applied to weighing of powder materials |
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| CN202210917164.5A CN115355972A (en) | 2022-08-01 | 2022-08-01 | Weightless metering method and device applied to weighing of powder materials |
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Effective date of registration: 20240315 Address after: Qisha Industrial Zone, Qisha Town, Gangkou District, Fangchenggang City, Guangxi Zhuang Autonomous Region (Jinchuan Industrial Park) Applicant after: GUANGXI JINCHUAN NON-FERROUS METALS CO.,LTD. Country or region after: China Applicant after: Jinchuan Group Copper Gui Co.,Ltd. Address before: 538002 Qisha Town Industrial Park, Gangkou District, Fangchenggang City, Guangxi Zhuang Autonomous Region (Jinchuan Industrial Park) Applicant before: GUANGXI JINCHUAN NON-FERROUS METALS CO.,LTD. Country or region before: China Applicant before: JINCHUAN GROUP Co.,Ltd. |