Automatic balance control method for grinding process

Abstract

The invention discloses an automatic balance control method for a grinding process, and belongs to the technical field of automatic control of grinding equipment. In order to solve the problems of frequent equipment failure and low production efficiency caused by imbalance of operating parameters such as temperature and pressure in a grinding process, the method mainly comprises the following steps: comprehensively collecting key parameters such as outlet temperature, feeding pump rotating speed, duplex filter pressure difference and inlet temperature, and constructing multi-dimensional collaborative automatic balance control logic; comprehensive adjustment of temperature, pressure and operation stability is achieved through linkage PID adjustment, pressure difference interlocking control and staged rotating speed control of the main machine and the feeding pump. According to the invention, the overtemperature and overpressure shutdown rate can be effectively reduced while the grinding effect is ensured, and the equipment utilization rate and the production efficiency are improved.

Description

Technical Field

[0001] This invention belongs to the field of automated control technology for grinding equipment, and specifically relates to an automatic balancing control method for a grinding process. Background Technology

[0002] like Figure 1 The diagram shows the rough grinding process flow, as follows: Figure 2 The diagram shows the fine grinding process, with the core equipment being a coarse grinding mill and a fine grinding mill, hereinafter collectively referred to as nano-mills. In addition to the nano-mills, the grinding system also includes auxiliary devices such as a feed pump, scraper filter, pipeline iron separator, mixing tank, and sealing fluid circulation pump.

[0003] The existing grinding process lacks an automatic balancing control system, resulting in significant fluctuations in the rotational speed of the nanomill main unit, the speed of the feed pump, and the pressure in the grinding chamber during operation. Due to imperfect control logic and the lack of an interlocking automatic adjustment mechanism between various devices, the rotational speed of the main unit and the speed of the feed pump mainly rely on manual adjustment, making it difficult for operators to achieve dynamic monitoring and precise control throughout the entire process.

[0004] from Figure 3 The fluctuations shown indicate that the grinding chamber pressure frequently exceeds the reasonable range, often resulting in overpressure and equipment shutdowns. Simultaneously, the unstable speeds of the main unit and the feed pump cause significant temperature fluctuations at the discharge port, frequently triggering equipment shutdowns due to overheating. These unstable operating conditions lead to frequent equipment failures due to overheating and overpressure, resulting in low equipment utilization and severely impacting production continuity and efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide an automatic balancing control method for the grinding process. By comprehensively collecting key parameters such as outlet temperature, feed pump speed, dual filter pressure difference, and inlet temperature, multi-dimensional collaborative automatic balancing control is implemented to solve the problems of frequent equipment failures and low production efficiency caused by the imbalance of the above parameters in the existing grinding process.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows.

[0007] An automatic balancing control method for a grinding process includes the following steps: 1) After receiving the power-on command, start the nano-mill host. When the host speed reaches the first speed threshold, start the feed pump. 2) Detect the pressure difference of the dual filter. When the pressure difference reaches the first pressure difference threshold, reduce the speed of the feed pump to the speed of the first feed pump and keep the main unit speed at the preset value; otherwise, proceed to step 3). 3) Detect the outlet temperature of the nanomill, compare the outlet temperature with the set outlet temperature, and adjust the main unit speed according to the deviation value ΔT between the two using the proportional-integral-derivative PID control method. 4) When the main unit speed drops to the minimum speed threshold, stop further speed reduction, activate the PID control of the feed pump, and adjust the feed pump speed according to the change of outlet temperature; 5) When ΔT is less than or equal to zero, detect the inlet temperature of the nano mill and compare it with the set inlet temperature. If the inlet temperature is higher than the set inlet temperature, increase the speed of the feed pump to remove the heat. 6) When the inlet temperature is lower than or equal to the set inlet temperature, the feed pump speed is set in stages according to the system running time. If necessary, switch to fixed parameter control mode or PID adjustment mode to keep the nanomill in the best power state.

[0008] Furthermore, in step 3), the PID control method is as follows: when the outlet temperature is higher than the set outlet temperature, the host speed is reduced; when the outlet temperature is lower than the set outlet temperature, the host speed is increased.

[0009] Furthermore, the adjustment rules for PID control in step 3) include: When ΔT is in the first temperature difference range, the main engine speed decreases by the first speed reduction. When ΔT is in the second temperature difference range, the main engine speed decreases by the second speed reduction rate; When ΔT continues to exceed the set duration, the host speed continues to decrease to the minimum speed threshold.

[0010] Furthermore, the PID control adjustment rules for the feed pump in step 4) include: When ΔT is in the first temperature difference range, the feed pump speed increases and the first feed pump rises. When ΔT is in the second temperature difference range, the feed pump speed increases and the second feed pump rises. When ΔT is greater than or equal to the third temperature difference threshold, the feed pump speed is increased to the maximum speed value; When ΔT is less than or equal to zero, the feed pump speed remains at the base speed value or decreases according to PID calculation, but does not fall below the minimum speed value.

[0011] Furthermore, in step 5), when the inlet temperature is higher than the set inlet temperature, the feed pump speed increases by a preset increment until the outlet temperature returns to the target temperature range, at which point the automatic control logic is restored.

[0012] Furthermore, the phased control of the feed pump speed in step 6) includes: the first stage speed, the second stage speed, the third stage speed, and the fourth stage speed, respectively, when the system operation time is in the first period, the second period, the third period, and the fourth period.

[0013] The beneficial effects achieved by this invention are as follows.

[0014] 1. Synergistic Effect of Temperature Control: This invention uses the outlet temperature of the nanomill as the core control variable. First, a PID feedback regulation relationship is established between the outlet temperature and the main machine speed, linking temperature and main machine speed holistically and laying the foundation for temperature control. When the main machine speed is below the minimum speed threshold (e.g., 455 rpm), a PID positive regulation logic is added between the feed pump and the outlet temperature. When the main machine speed adjustment is limited and cannot further reduce the temperature, the feed pump speed is increased to accelerate the material flow rate and remove excess heat. When the inlet temperature exceeds the set inlet temperature (e.g., 32℃), the feed pump speed is directly increased for emergency heat dissipation. This multi-condition, multi-path temperature control strategy works together to ensure the outlet temperature remains stable at the set outlet temperature (e.g., 47℃), significantly reducing over-temperature shutdowns.

[0015] 2. Synergistic effect of pressure and blockage control: This invention interlocks the pressure difference between the feed pump and the dual filter. When the pressure difference reaches the first pressure difference threshold (e.g., 70 kPa), the feed pump speed is automatically reduced to prevent material blockage in the filtration stage. This measure ensures the continuity and stability of material conveying within the system, avoids sudden pressure rise in the grinding chamber caused by blockage, and helps maintain the grinding chamber pressure within the set pressure range (e.g., 0.6~1.2 bar) during startup and operation. It also indirectly works with the temperature control scheme to reduce downtime caused by abnormal pressure.

[0016] 3. Synergistic effect of equipment power and operational stability: This invention controls the speed of the feed pump in segments according to the running time, and selects fixed parameters or puts in PID logic at different stages to keep the nanomill in the optimal power state at all times, reducing the interference of power fluctuations on temperature and pressure control; in addition, the feed pump is started only after the main machine speed reaches the first speed threshold (e.g., 150 rpm), which ensures the rationality of the equipment operation sequence, avoids start-up shock, and further improves the overall stability and reliability of the system operation.

[0017] 4. Overall Improvement in Production Performance: Through the multi-dimensional synergistic control of temperature, pressure, and operational stability, this invention significantly reduces downtime caused by over-temperature and over-pressure. In the embodiments described below, the downtime rate due to excessively high outlet temperature decreased by approximately 80%, and the downtime rate due to over-pressure at startup decreased by approximately 70%, resulting in a significant improvement in equipment utilization. Simultaneously, the average grinding time was shortened by 1.7 hours, the average fine grinding capacity increased by 10.5%, and the total fine grinding capacity increased from 2114 T / M to 2345 T / M, representing a 10.9% increase in monthly capacity, effectively improving production efficiency and output stability. Attached Figure Description

[0018] Figure 1 This is a flowchart of the rough grinding process.

[0019] Figure 2 This is a flowchart of the fine grinding process.

[0020] Figure 3 The graph shows the fluctuation of speed of the existing nanomilling machine, feed pump and pressure in the grinding chamber.

[0021] Figure 4 This is a flowchart illustrating the automatic balancing control process of the grinding step in an embodiment of the present invention.

[0022] Figure 5 The graph shows the rotational speed of the nanomilling machine, the feed pump, and the pressure fluctuation in the grinding chamber, according to an embodiment of the present invention. Detailed Implementation

[0023] To make the various technical features, advantages, or effects of the present invention more apparent and understandable, detailed descriptions are provided below through embodiments.

[0024] This embodiment provides an automatic balancing control method for a grinding process, the process of which is as follows: Figure 4 As shown, the steps include the following.

[0025] S1: Start-up and feed pump start-up.

[0026] Upon receiving the start-up command, the nano-mill main unit is started first. When the main unit speed reaches 150 rpm or more, the feed pump is started to ensure the orderly operation of the equipment.

[0027] S2: Dual filter differential pressure detection and feed pump interlock control.

[0028] Determine if the differential pressure of the dual filter reaches 70 kPa. If so, reduce the feed pump speed to 20 rpm and keep the main unit speed at the preset value to prevent material blockage; If not, proceed to the next step to determine the outlet temperature of the nanomill.

[0029] S3: PID (proportional-integral-derivative) control of the outlet temperature.

[0030] The outlet temperature of the nanomill is used as the main control parameter, and PID control is performed by comparing it with the outlet temperature setpoint. For example, the outlet temperature setpoint... At that time, the main unit speed is regulated by PID positive action to keep the feed pump speed at 22 rpm. When the main unit speed decreases, the outlet temperature decreases accordingly, thereby achieving temperature control.

[0031] The PID controller calculates the current outlet temperature T and the setpoint in real time. deviation And adjust according to the following rules.

[0032] when When the temperature exceeds the limit, the PID output signal reduces the host speed, and the reduction is proportional to the magnitude and duration of ΔT.

[0033] For example: ① (Slight overheating): Adjust the main unit speed by a proportional coefficient to reduce it by approximately 5-8 rpm; ② (Severe overheating): The integral action is superimposed on the proportional regulation, which increases the cumulative regulation and reduces the main engine speed by about 20~30 rpm; ③ If the temperature continues to exceed the limit (e.g., it does not drop within 30 seconds), the main unit speed will continue to decrease until it reaches the set minimum speed of 455 rpm, at which point the subsequent control logic will be triggered.

[0034] when If the temperature is not exceeded, proceed to step S5 to determine the inlet temperature.

[0035] S4: Temperature control compensation for the feed pump when the main unit is at low speed.

[0036] During the main unit speed adjustment process, determine whether it has dropped to the minimum speed of 455 rpm; If not, keep the feed pump speed at 22 rpm; If so, to ensure the grinding effect, stop further speed reduction and activate the PID control of the feed pump to monitor the outlet temperature in real time.

[0037] When the outlet temperature rises, the feed pump speed is increased to increase the material flow rate, thereby removing more heat from the grinding chamber and lowering the outlet temperature. The higher the outlet temperature, the higher the feed pump speed.

[0038] The adjustment rules for the feed pump are as follows: ① ( ): Increase the feed pump speed by 1 rpm (e.g., from 22 rpm to 23 rpm); ② Increase the feed pump speed by 2 rpm (e.g., from 22 rpm to 24 rpm). ③ The feed pump speed is directly increased to the upper limit of 30 rpm to quickly enhance heat dissipation; ④ The feed pump speed should be maintained at the base value or reduced according to PID calculation, but not lower than 20 rpm.

[0039] S5: Imported temperature interlock control.

[0040] when At that time, determine the relationship between the inlet temperature of the nanomill and its set value, for example, the set value is 32℃; If the inlet temperature Then, increase the feed pump speed from 22 rpm to 23 rpm to forcibly remove heat from the grinding chamber until the outlet temperature returns to the target range (e.g., After that, the automatic control logic is restored; If the inlet temperature Then proceed to step S6.

[0041] S6: Time-sharing feed pump speed control.

[0042] Based on the system runtime, the feed pump speed is controlled at a fixed value according to the following stages: 0~3 hours: 20rpm; 3~6 hours: 21rpm; 6~9 hours: 22rpm; ≥9 hours: 23 rpm.

[0043] Under specific conditions, the system can switch to fixed parameter control mode or PID regulation mode to ensure the nanomill operates at its optimal power. In PID regulation mode, the main motor speed acts as the actuator, employing a reaction-based regulation method: the main motor speed decreases when the outlet temperature rises, and increases when the outlet temperature falls. The main motor speed directly affects the grinding intensity; higher speeds generate more frictional heat and thus higher outlet temperatures. Reducing the speed decreases heat generation, while increasing it increases heat generation, thereby dynamically offsetting fluctuations in outlet temperature. Within its allowable range, the main motor speed automatically responds to temperature changes, prioritizing speed adjustment above 455 rpm and potentially triggering other auxiliary logic below this value.

[0044] Through the above control logic, multi-dimensional collaborative automatic balance control with the nanomill outlet temperature as the core parameter is realized. While ensuring the grinding effect, it effectively suppresses equipment shutdown caused by over-temperature and over-pressure, and improves production continuity and operating efficiency.

[0045] like Figure 5 As shown in the figure, the operating status of the nanomill main machine speed, feed pump speed and grinding chamber pressure in this embodiment can be seen.

[0046] 1) The grinding chamber pressure of the coarse grinding mill and the fine grinding mill is stably maintained within the range of 0.6~1.2 bar, which effectively avoids the occurrence of overpressure.

[0047] 2) The main unit speed and the feed pump speed are kept stable through automatic adjustment, so that the outlet temperature is kept stable at about 47°C, and the overheating situation is significantly reduced.

[0048] 3) Equipment failures caused by overheating and overpressure have been significantly reduced. Specifically, the number of shutdowns caused by excessively high outlet temperature per nanomill has been reduced by about 80%, and the number of shutdowns caused by overpressure during startup has been reduced by about 70%, resulting in a significant improvement in equipment utilization.

[0049] 4) The average grinding time was shortened by 1.7 hours, the average fine grinding capacity was increased by 10.5%, the total fine grinding capacity was increased from 2114T / M to 2345T / M, and the monthly capacity was increased by 10.9%, which significantly improved production efficiency.

[0050] In summary, this embodiment uses the outlet temperature of the nanomill as the core control variable and optimizes the control logic to achieve automatic coordinated adjustment of related equipment parameters, ultimately achieving the following effects: the outlet temperature remains constant, the mill chamber pressure is stable within the ideal range during the start-up phase, equipment failures caused by overheating and overpressure are significantly reduced, and equipment utilization and production efficiency are greatly improved.

[0051] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the protection scope of the present invention, which is defined by the claims.

Claims

1. An automatic balancing control method for a grinding process, characterized in that, Includes the following steps: 1) After receiving the power-on command, start the nano-mill host. When the host speed reaches the first speed threshold, start the feed pump. 2) Detect the pressure difference of the dual filter. When the pressure difference reaches the first pressure difference threshold, reduce the speed of the feed pump to the speed of the first feed pump and keep the main unit speed at the preset value; otherwise, proceed to step 3). 3) Detect the outlet temperature of the nanomill, compare the outlet temperature with the set outlet temperature, and adjust the main unit speed according to the deviation value ΔT between the two using the proportional-integral-derivative PID control method. 4) When the main unit speed drops to the minimum speed threshold, stop further speed reduction, activate the PID control of the feed pump, and adjust the feed pump speed according to the change of outlet temperature; 5) When ΔT is less than or equal to zero, detect the inlet temperature of the nano mill and compare it with the set inlet temperature. If the inlet temperature is higher than the set inlet temperature, increase the speed of the feed pump to remove the heat. 6) When the inlet temperature is lower than or equal to the set inlet temperature, the feed pump speed is set in stages according to the system running time. If necessary, switch to fixed parameter control mode or PID adjustment mode to keep the nanomill in the best power state.

2. The method as described in claim 1, characterized in that, In step 3), the PID control method is as follows: when the outlet temperature is higher than the set outlet temperature, the host speed is reduced; when the outlet temperature is lower than the set outlet temperature, the host speed is increased.

3. The method as described in claim 2, characterized in that, The adjustment rules for PID control in step 3) include: When ΔT is in the first temperature difference range, the main engine speed decreases by the first speed reduction. When ΔT is in the second temperature difference range, the main engine speed decreases by the second speed reduction rate; When ΔT continues to exceed the set duration, the host speed continues to decrease to the minimum speed threshold.

4. The method as described in claim 1, characterized in that, The PID control adjustment rules for the feed pump in step 4) include: When ΔT is in the first temperature difference range, the feed pump speed increases and the first feed pump rises. When ΔT is in the second temperature difference range, the feed pump speed increases and the second feed pump rises. When ΔT is greater than or equal to the third temperature difference threshold, the feed pump speed is increased to the maximum speed value; When ΔT is less than or equal to zero, the feed pump speed remains at the base speed value or decreases according to PID calculation, but does not fall below the minimum speed value.

5. The method as described in claim 1, characterized in that, In step 5), when the inlet temperature is higher than the set inlet temperature, the feed pump speed increases by a preset increment until the outlet temperature returns to the target temperature range, at which point the automatic control logic is restored.

6. The method as described in claim 1, characterized in that, Step 6) The phased control of the feed pump speed includes: when the system is in the first period, the second period, the third period, and the fourth period, the corresponding speeds are the first stage speed, the second stage speed, the third stage speed, and the fourth stage speed, respectively.

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