A high-efficiency intelligent control method for ring rolling mill oil cylinder for ring forming control

Abstract

The present application belongs to the technical field of ring rolling mill control, and particularly relates to a high-efficiency intelligent control method for ring rolling mill oil cylinder for ring forming control. The method comprises: initializing control parameters; collecting oil cylinder displacement, chamber pressure and system bus pressure in real time; judging whether to activate differential pressure driving mode according to the differential pressure enable flag, so that the rod cavity and the rodless cavity form a differential circuit; identifying automatic or manual operation mode; running position closed-loop control and implementing pressure protection in automatic mode, and directly driving the oil cylinder action according to the differential pressure state in manual mode; and according to the adaptive enable flag, dynamically matching the optimal parameter group from multiple groups of graded control parameters according to the real-time load rate. The present application reduces the energy consumption by reducing the pump station flow demand through the differential pressure mode, and improves the position control and multi-cylinder synchronization accuracy under all working conditions through load adaptive parameter matching, thereby solving the technical problems of traditional ring rolling mill oil cylinder control, such as difficulty in balancing high speed and heavy load, large multi-cylinder collaborative disturbance and high energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of ring rolling mill control technology, and specifically relates to a high-efficiency intelligent control method for ring rolling mill cylinders used for ring forming control. Background Technology

[0002] A ring rolling mill is a continuous, localized plastic forming process equipment that, through the coordinated action of various rolls, reduces the thickness of a ring, increases its diameter, and shapes its cross-sectional profile. It is the most effective technical means to improve the microstructure and properties of rings, increase material utilization, and shorten the manufacturing cycle. In a ring rolling mill, at least five motion axes typically require coordinated operation. The hydraulic cylinder, as a key actuator, directly determines the quality of the ring forming and the production efficiency.

[0003] Currently, the hydraulic control system for ring rolling mill cylinders mainly adopts a centralized hydraulic system layout. In existing technical solutions, a centralized hydraulic system design is typically used, with different functional cylinders receiving driving pressure through the same hydraulic system. Cylinder movements are controlled by corresponding valve groups within the hydraulic system. Regarding cylinder control, existing technologies often use adjustable synchronization valves to control two hydraulic cylinders to achieve synchronized roll movement; or they use servo cylinders with displacement sensors, with computer-controlled forward and backward positions. In hydraulic circuit design, some solutions employ differential control circuits to ensure constant pressure and smooth retraction when the cylinder passively retracts. However, the above-mentioned traditional control schemes still have the following shortcomings in practical applications: First, heavy-load movement is prone to impact and lacks smooth operation. The cylinders of a ring rolling mill bear large loads during rolling, and these loads fluctuate drastically. In electro-hydraulic servo systems, the rolling mill hydraulic system is a complex device with high load capacity, numerous disturbance factors, severe cross-coupling, and high requirements for control precision and response speed. Pressure fluctuations in the oil supply system significantly affect control precision, and the traditional centralized hydraulic system layout makes it easy for cylinders to disturb each other, resulting in large impacts and poor stability during heavy-load operation.

[0004] Secondly, the control performance, including adaptive speed regulation, pressure regulation, and position synchronization, is poor. Inconsistencies exist between the hydraulic servo position systems on the mill's drive side and operating side, easily leading to asynchrony between the two sides. Existing control strategies are mostly fixed-parameter control, which struggles to cope with parameter perturbations and external load fluctuations. When external load disturbances change significantly, traditional PID control struggles to guarantee the system's position tracking accuracy and robustness. This is particularly challenging in ring mills where multiple cylinders work in tandem, where maintaining synchronization accuracy between cylinders is a significant challenge.

[0005] Third, energy utilization is low and energy consumption is too high. Existing ring rolling mill hydraulic systems generally suffer from high energy consumption. During operation, especially under significant load variations, high-pressure hydraulic systems often experience high energy consumption and waste, manifesting as heat or pressure fluctuations, leading to low system efficiency. Although some research has attempted optimization using load-sensitive pump technology, there is still considerable room for improvement in overall energy utilization.

[0006] In summary, existing cylinder control technology for ring rolling mills is insufficient to simultaneously meet the control requirements of heavy-load, low-speed working feed and no-load travel under low flow conditions. The control accuracy and synchronization accuracy are inadequate, and the energy utilization rate is low. There is an urgent need for a more efficient and intelligent cylinder control method. Summary of the Invention

[0007] To address the aforementioned problems, the purpose of this invention is to provide a highly efficient and intelligent control method for the cylinders of a ring rolling mill used for ring forming control. This invention utilizes a differential pressure mode to directly replenish the rodless chamber with oil returning from the rod chamber, increasing the movement speed under the same oil supply flow rate, significantly reducing pump station power consumption and overflow losses, and improving energy utilization. Through position-pressure dual closed-loop series control combined with an adaptive mechanism based on real-time load rate dynamic matching of graded control parameters, the system maintains optimal control performance across the entire load range, effectively solving the problems of light-load oscillation and heavy-load response hysteresis in fixed-parameter control, significantly improving the cylinder position control accuracy and multi-cylinder synchronization accuracy, and ensuring the quality of ring forming.

[0008] The technical solution of this invention is: a highly efficient and intelligent control method for a ring mill cylinder used for ring forming control, comprising the following steps: Step 1, Initialize control parameters: When the ring mill is powered on, set the initial configuration, which includes at least the differential pressure enable flag, adaptive enable flag, operation mode flag, position target value, pressure safety threshold, and several sets of control parameters divided by load level. Step 2, Real-time Status Acquisition: During the operation of the ring mill, the system bus pressure, actual displacement of the cylinder, actual pressure of each chamber, hydraulic pump speed, hydraulic pump load, and control valve opening data are continuously acquired through sensors and fieldbus interfaces. Step 3, Differential pressure drive mode determination: According to the differential pressure enable flag, if the flag is valid, the differential pressure drive mode is activated, that is, by controlling the hydraulic valve group to form a differential circuit between the rod chamber and the rodless chamber of the cylinder, thereby increasing the cylinder movement speed under the same pump station oil supply flow; if the flag is invalid, the conventional non-differential pressure drive mode is used. Step 4, Operation Mode Recognition and Control: According to the operation mode flag, if it is automatic mode, proceed to step 5; if it is manual mode, receive the external manual operation signal, and directly control the hydraulic valve group to drive the oil cylinder to perform forward or backward actions according to the drive mode determined in step 3. Step 5, Position closed-loop control in automatic mode: With the target position value as a given, and the actual displacement collected as feedback, the position closed-loop adjustment algorithm is run to generate the control quantity that drives the hydraulic cylinder to move; during the adjustment process, the pressure of each chamber collected is compared with the pressure safety threshold. When any pressure exceeds the threshold, the output amplitude of the control quantity is immediately limited or the hydraulic power is cut off to achieve pressure protection. Step Six, Adaptive Control Parameter Matching: During the execution of Step Five, if the adaptive enable flag is valid, the current load rate is calculated based on the collected cylinder pressure and system bus pressure. Based on the load rate, a corresponding set of control parameters is selected from the several sets of control parameters, and this set of parameters is replaced with the control parameters of the current closed-loop regulator after being processed without disturbance. If the adaptive enable flag is invalid, the default control parameters are maintained without change. Step 7: After completing the control calculation for the current cycle, return to Step 2 to continue to the next cycle, thus achieving real-time continuous control of the hydraulic cylinder.

[0009] Furthermore, in step three, the differential circuit formed between the rod chamber and the rodless chamber of the cylinder by controlling the hydraulic valve group is specifically as follows: when the cylinder extends, while oil is introduced into the rodless chamber, the return oil line of the rod chamber is switched to connect with the oil inlet line of the rodless chamber, so that the oil discharged from the rod chamber is replenished to the rodless chamber, thereby using the area difference between the two chambers to achieve differential speed increase.

[0010] Furthermore, the position closed-loop adjustment algorithm described in step five uses a dual closed-loop series control structure with an inner pressure loop and an outer position loop. The outer loop position controller outputs a speed or pressure command to the inner loop pressure controller based on the position deviation. The inner loop pressure controller calculates the servo valve opening based on the deviation between this command and the actual pressure. The pressure protection is achieved through limiting by the inner loop pressure controller. Both the position closed-loop adjustment algorithm and the servo valve opening control are implemented using the following PID algorithm: ; In the formula, The gain is proportional; input is prohibited when it equals 0. Points are awarded; when the score is 0, no further input is allowed. When the derivative is zero, input is prohibited. This is the deviation value.

[0011] Furthermore, the adaptive enable flag in step six includes three selectable states: adaptive in differential pressure mode, adaptive in normal mode, and adaptive disabled. The user selects at least one of the three states based on the actual operating conditions.

[0012] Furthermore, in step six, the selection of a corresponding set of control parameters from the several sets of control parameters based on the load rate specifically involves: dividing the load rate into multiple continuous level intervals, pre-storing a set of control parameters in each level interval, which includes at least proportional gain, integral gain, derivative gain, velocity feedforward coefficient, and acceleration limit value; after calculating the current load rate, determining its level interval, and using the parameter set corresponding to that interval as the selection result.

[0013] Furthermore, the several sets of control parameters are stored in the controller's non-volatile memory in the form of a hierarchical index table, with the load rate level as the index key and the control parameter group as the index value. When selecting, the corresponding parameter group is read directly through the index key.

[0014] Furthermore, the disturbance-free transition processing mentioned in step six refers to: when replacing control parameters, proportionally correcting the integral accumulation term of the closed-loop controller according to the difference between the old and new parameters, and limiting the rate of change of the output control quantity, so that the control quantity remains continuous before and after parameter switching, avoiding cylinder shock or oscillation caused by parameter abrupt changes.

[0015] Furthermore, the switching between automatic and manual modes in step four is a bidirectional, non-disruptive switching: when switching from automatic mode to manual mode, the controller immediately stops the position closed-loop calculation and transfers control to the manual operation signal; when switching from manual mode to automatic mode, the current actual displacement value is assigned to the position target value, so that the initial state of the closed-loop control is consistent with the current cylinder position, preventing position jumps during mode switching.

[0016] Furthermore, the pressure protection described in step five also includes an overload lockout mechanism: when the pressure exceeds the safety threshold, the system enters a fault protection state, which can only be released through manual reset to ensure the safety of the equipment and workpiece.

[0017] Furthermore, in step four, in manual mode, the differential pressure drive method or conventional drive method determined in step three is also executed. That is, if the differential pressure enable is effective during manual operation, the differential circuit is automatically engaged, so that manual jogging operation can also obtain the fast response characteristics under small flow rate.

[0018] The technical advantages of this invention are as follows: 1. By setting an independent differential pressure enable flag, this invention flexibly activates the differential pressure drive mode according to actual working conditions. When the differential pressure mode is activated, the combined control of the hydraulic valve group forms a differential circuit between the rod chamber and the rodless chamber of the cylinder. The oil discharged from the rod chamber directly replenishes the rodless chamber to participate in the drive, instead of flowing entirely back to the oil tank. This mechanism allows the cylinder to achieve a higher movement speed under the same pump station supply flow conditions; in other words, under the premise of meeting the same speed control requirements, the system can significantly reduce the demand on the hydraulic pump output flow, thereby reducing the power consumption and overflow loss of the hydraulic pump. Compared with traditional non-differential pressure control methods, the energy-saving effect of this invention is particularly prominent under no-load and light-load conditions, effectively reducing the operating energy consumption of the ring rolling mill hydraulic system. 2. In automatic mode, this invention employs a dual closed-loop control structure consisting of a position outer loop and a pressure inner loop connected in series. The position outer loop ensures accurate displacement tracking, while the pressure inner loop suppresses the interference of load fluctuations on the position loop in real time. Together, they achieve high-precision position closed-loop control. Furthermore, this invention introduces an adaptive enable flag and a hierarchical matching mechanism for control parameters. When the adaptive function is activated, the system calculates the current load rate based on the real-time collected cylinder pressure and system bus pressure. Based on the load rate, it dynamically selects the optimal set of pre-stored hierarchical control parameters, applies it to the closed-loop regulator after a seamless switching process. This mechanism ensures that the control parameters are always matched to the current load condition. High-gain parameters are used under light loads to ensure rapid response, while low-gain parameters are used under heavy loads to ensure system stability. This effectively suppresses control disturbances between cylinders common in traditional centralized hydraulic systems, significantly improves the synchronous motion accuracy of dual or multi-cylinder systems, and thus improves the forming quality and dimensional consistency of the components. 3. The differential pressure enable flag and the adaptive enable flag of this invention are independent of each other and orthogonally combined to form four selectable working modes, covering the full range of requirements from "conventional fixed parameter mode" to "optimal adaptive differential pressure mode", thereby ensuring the smooth and continuous rolling process and avoiding product quality fluctuations caused by parameter switching.

[0019] The following will provide further explanation in conjunction with the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a flowchart of an efficient and intelligent control method for a ring rolling mill cylinder used for ring forming control, according to the present invention. Detailed Implementation

[0021] Example 1 like Figure 1 As shown, a highly efficient and intelligent control method for a ring mill cylinder used for ring forming control includes the following steps: Step 1, Initialize control parameters: When the ring mill is powered on, set the initial configuration, which includes at least the differential pressure enable flag, adaptive enable flag, operation mode flag, position target value, pressure safety threshold, and several sets of control parameters divided by load level. Step 2, Real-time Status Acquisition: During the operation of the ring mill, the system bus pressure, actual displacement of the cylinder, actual pressure of each chamber, hydraulic pump speed, hydraulic pump load, and control valve opening data are continuously acquired through sensors and fieldbus interfaces. Step 3, Differential pressure drive mode determination: According to the differential pressure enable flag, if the flag is valid, the differential pressure drive mode is activated, that is, by controlling the hydraulic valve group to form a differential circuit between the rod chamber and the rodless chamber of the cylinder, thereby increasing the cylinder movement speed under the same pump station oil supply flow; if the flag is invalid, the conventional non-differential pressure drive mode is used. Step 4, Operation Mode Recognition and Control: According to the operation mode flag, if it is automatic mode, proceed to step 5; if it is manual mode, receive the external manual operation signal, and directly control the hydraulic valve group to drive the oil cylinder to perform forward or backward actions according to the drive mode determined in step 3. Step 5, Position closed-loop control in automatic mode: With the target position value as a given, and the actual displacement collected as feedback, the position closed-loop adjustment algorithm is run to generate the control quantity that drives the hydraulic cylinder to move; during the adjustment process, the pressure of each chamber collected is compared with the pressure safety threshold. When any pressure exceeds the threshold, the output amplitude of the control quantity is immediately limited or the hydraulic power is cut off to achieve pressure protection. Step Six, Adaptive Control Parameter Matching: During the execution of Step Five, if the adaptive enable flag is valid, the current load rate is calculated based on the collected cylinder pressure and system bus pressure. Based on the load rate, a corresponding set of control parameters is selected from the several sets of control parameters, and this set of parameters is replaced with the control parameters of the current closed-loop regulator after being processed without disturbance. If the adaptive enable flag is invalid, the default control parameters are maintained without change. Step 7: After completing the control calculation for the current cycle, return to Step 2 to continue to the next cycle, thus achieving real-time continuous control of the hydraulic cylinder.

[0022] Furthermore, in step three, the differential circuit formed between the rod chamber and the rodless chamber of the cylinder by controlling the hydraulic valve group is specifically as follows: when the cylinder extends, while oil is introduced into the rodless chamber, the return oil line of the rod chamber is switched to connect with the oil inlet line of the rodless chamber, so that the oil discharged from the rod chamber is replenished to the rodless chamber, thereby using the area difference between the two chambers to achieve differential speed increase.

[0023] Furthermore, the position closed-loop adjustment algorithm described in step five uses a dual closed-loop series control structure with an inner pressure loop and an outer position loop. The outer loop position controller outputs a speed or pressure command to the inner loop pressure controller based on the position deviation. The inner loop pressure controller calculates the servo valve opening based on the deviation between this command and the actual pressure. The pressure protection is achieved through limiting by the inner loop pressure controller. Both the position closed-loop adjustment algorithm and the servo valve opening control are implemented using the following PID algorithm: ; In the formula, The gain is proportional; input is prohibited when it equals 0. Points are awarded; when the score is 0, no further input is allowed. When the derivative is zero, input is prohibited. This is the deviation value.

[0024] Furthermore, the adaptive enable flag in step six includes three selectable states: adaptive in differential pressure mode, adaptive in normal mode, and adaptive disabled. The user selects at least one of the three states based on the actual operating conditions.

[0025] Furthermore, in step six, the selection of a corresponding set of control parameters from the several sets of control parameters based on the load rate specifically involves: dividing the load rate into multiple continuous level intervals, pre-storing a set of control parameters in each level interval, which includes at least proportional gain, integral gain, derivative gain, velocity feedforward coefficient, and acceleration limit value; after calculating the current load rate, determining its level interval, and using the parameter set corresponding to that interval as the selection result.

[0026] Furthermore, the several sets of control parameters are stored in the controller's non-volatile memory in the form of a hierarchical index table, with the load rate level as the index key and the control parameter group as the index value. When selecting, the corresponding parameter group is read directly through the index key.

[0027] Furthermore, the disturbance-free transition processing mentioned in step six refers to: when replacing control parameters, proportionally correcting the integral accumulation term of the closed-loop controller according to the difference between the old and new parameters, and limiting the rate of change of the output control quantity, so that the control quantity remains continuous before and after parameter switching, avoiding cylinder shock or oscillation caused by parameter abrupt changes.

[0028] Furthermore, the switching between automatic and manual modes in step four is a bidirectional, non-disruptive switching: when switching from automatic mode to manual mode, the controller immediately stops the position closed-loop calculation and transfers control to the manual operation signal; when switching from manual mode to automatic mode, the current actual displacement value is assigned to the position target value, so that the initial state of the closed-loop control is consistent with the current cylinder position, preventing position jumps during mode switching.

[0029] Furthermore, the pressure protection described in step five also includes an overload lockout mechanism: when the pressure exceeds the safety threshold, the system enters a fault protection state, which can only be released through manual reset to ensure the safety of the equipment and workpiece.

[0030] Furthermore, in step four, in manual mode, the differential pressure drive method or conventional drive method determined in step three is also executed. That is, if the differential pressure enable is effective during manual operation, the differential circuit is automatically engaged, so that manual jogging operation can also obtain the fast response characteristics under small flow rate.

[0031] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A highly efficient and intelligent control method for a ring mill cylinder used for ring forming control, characterized in that: Includes the following steps: Step 1, Initialize control parameters: When the ring mill is powered on, set the initial configuration, which includes at least the differential pressure enable flag, adaptive enable flag, operation mode flag, position target value, pressure safety threshold, and several sets of control parameters divided by load level. Step 2, Real-time Status Acquisition: During the operation of the ring mill, the system bus pressure, actual displacement of the cylinder, actual pressure of each chamber, hydraulic pump speed, hydraulic pump load, and control valve opening data are continuously acquired through sensors and fieldbus interfaces. Step 3, Differential pressure drive mode determination: According to the differential pressure enable flag, if the flag is valid, the differential pressure drive mode is activated, that is, by controlling the hydraulic valve group to form a differential circuit between the rod chamber and the rodless chamber of the cylinder, thereby increasing the cylinder movement speed under the same pump station oil supply flow; if the flag is invalid, the conventional non-differential pressure drive mode is used. Step 4, Operation Mode Recognition and Control: According to the operation mode flag, if it is automatic mode, proceed to step 5; if it is manual mode, receive the external manual operation signal, and directly control the hydraulic valve group to drive the oil cylinder to perform forward or backward actions according to the drive mode determined in step 3. Step 5, Position closed-loop control in automatic mode: With the target position value as a given, and the actual displacement collected as feedback, the position closed-loop adjustment algorithm is run to generate the control quantity that drives the hydraulic cylinder to move. During the adjustment process, the collected pressure of each chamber is compared with the pressure safety threshold. When any pressure exceeds the threshold, the output amplitude of the control quantity is immediately limited or the hydraulic power is cut off to achieve pressure protection. Step 6, Adaptive control parameter matching: During the execution of step 5, if the adaptive enable flag is valid, the current load rate is calculated based on the collected cylinder pressure and system bus pressure. Based on the load rate, a corresponding set of control parameters is selected from the several sets of control parameters, and the set of parameters is replaced with the control parameters of the current closed-loop regulator after being processed without disturbance. If the adaptive enable flag is invalid, the default control parameters will remain unchanged. Step 7: After completing the control calculation for the current cycle, return to Step 2 to continue to the next cycle, thus achieving real-time continuous control of the hydraulic cylinder.

2. The efficient and intelligent control method for ring mill cylinders used for ring forming control according to claim 1, characterized in that, In step three, the differential circuit between the rod chamber and the rodless chamber of the cylinder is formed by controlling the hydraulic valve group. Specifically, when the cylinder extends, oil is introduced into the rodless chamber, and at the same time, the return oil line of the rod chamber is switched to connect with the oil inlet line of the rodless chamber, so that the oil discharged from the rod chamber is replenished to the rodless chamber, thereby using the area difference between the two chambers to achieve differential speed increase.

3. The efficient and intelligent control method for ring mill cylinders used for ring forming control according to claim 1, characterized in that, The position closed-loop adjustment algorithm described in step five uses a dual-closed-loop series control structure with an inner pressure loop and an outer position loop. The outer loop position controller outputs a speed or pressure command to the inner loop pressure controller based on the position deviation. The inner loop pressure controller calculates the servo valve opening based on the deviation between this command and the actual pressure. Pressure protection is achieved through limiting by the inner loop pressure controller. Both the position closed-loop adjustment algorithm and the servo valve opening control are implemented using the following PID algorithm: ； In the formula, The gain is proportional; input is prohibited when it equals 0. Points are awarded; when the score equals 0, no further input is allowed. When the derivative is zero, input is prohibited. This is the deviation value. The above parameters are used in different parameter groups to achieve the control function requirements of different working conditions.

4. The efficient and intelligent control method for ring mill cylinders used for ring forming control according to claim 1, characterized in that, The adaptive enable flag mentioned in step six includes three selectable states: adaptive in differential pressure mode, adaptive in normal mode, and adaptive disabled. The user selects at least one of the three states according to the actual working conditions.

5. The efficient and intelligent control method for ring mill cylinders used for ring forming control according to claim 1, characterized in that, Step six, which involves selecting a corresponding set of control parameters from the several sets of control parameters based on the load rate, specifically involves dividing the load rate into multiple consecutive level intervals, and pre-storing a set of control parameters in each level interval. These control parameters include at least proportional gain, integral gain, derivative gain, velocity feedforward coefficient, and acceleration limit value. After calculating the current load rate, determine its level range and use the parameter group corresponding to that range as the selection result.

6. The efficient and intelligent control method for ring mill cylinders used for ring forming control according to claim 5, characterized in that, The control parameters are stored in the controller's non-volatile memory in the form of a hierarchical index table, with the load rate level as the index key and the control parameter group as the index value. When selecting, the corresponding parameter group is read directly through the index key.

7. The efficient and intelligent control method for ring mill cylinders used for ring forming control according to claim 1, characterized in that, The disturbance-free transition processing mentioned in step six refers to: when replacing control parameters, proportionally correcting the integral accumulation term of the closed-loop controller according to the difference between the old and new parameters, and limiting the rate of change of the output control quantity, so that the control quantity remains continuous before and after parameter switching, avoiding cylinder shock or oscillation caused by sudden parameter changes.

8. The efficient and intelligent control method for ring mill cylinders used for ring forming control according to claim 1, characterized in that, The switching between automatic and manual modes in step four is a bidirectional, seamless switching: when switching from automatic mode to manual mode, the controller immediately stops position closed-loop calculation and transfers control to the manual operation signal; When switching from manual mode to automatic mode, the current actual displacement value is assigned to the position target value, so that the initial state of closed-loop control is consistent with the current position of the cylinder, preventing position jumps during mode switching.

9. A highly efficient and intelligent control method for a ring mill cylinder used for ring forming control according to claim 1, characterized in that, The pressure protection described in step five also includes an overload lockout mechanism: when the pressure exceeds the safety threshold, the system enters a fault protection state, which can only be released through manual reset to ensure the safety of the equipment and workpiece.

10. A highly efficient and intelligent control method for a ring mill cylinder used for ring forming control according to claim 1, characterized in that, In step four, in manual mode, the differential pressure drive method or conventional drive method determined in step three is also executed. That is, if the differential pressure enable is effective during manual operation, the differential circuit is automatically engaged, so that manual jogging operation can also obtain the fast response characteristics under small flow rate.

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