Magnesium alloy plate warm rolling dynamic tension control device and method

Abstract

The invention discloses a magnesium alloy plate warm rolling dynamic tension control device and method. The device comprises tension oil cylinders arranged at the two ends of a magnesium alloy plate, an oil pressure servo control valve stand, a PLC, a tension sensor, an oil pressure sensor and a clamp. An oil pressure servo control valve stand is connected with a tension oil cylinder through a tension cylinder oil pipe, a piston rod is connected with a clamp through a tension sensor to clamp the end of a plate, the tension sensor directly measures tension, and an oil pressure sensor monitors oil pressure of a rod cavity. The PLC adopts double-closed-loop control, an outer ring adjusts an oil pressure set value through tension deviation, an inner ring controls the opening degree of a servo valve through oil pressure deviation, and dynamic tension is optimized through flow feed-forward and inertia friction compensation. The method comprises the steps of clamping a plate, starting rolling, detecting tension and oil pressure in real time, and dynamically adjusting the opening degree of the servo valve. According to the method, the tension control precision is improved from + / -5.0% to + / -2.5%, the problems of adhesion, narrowing and belt breakage in the warm rolling of the thin magnesium alloy plate are solved, and the yield and the production efficiency are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of warm rolling of magnesium alloys, and relates to a device and method for dynamic tension control in the warm rolling of magnesium alloy sheets. Background Art

[0002] As a lightweight and high-strength metal material, magnesium alloys have significant advantages in engineering applications due to their low density, high specific stiffness and specific strength, good corrosion resistance, excellent heat dissipation performance, good machining performance, and easy recyclability. Especially in fields that require lightweight materials, such as electronic products, automotive manufacturing, aerospace industry, etc., magnesium alloys show broad application prospects and development space. With the continuous improvement of the requirements for material properties in modern industry, the production technology of magnesium alloy sheets is also continuously progressing. Among them, the warm rolling process is widely used because it can effectively improve the plastic deformation performance of magnesium alloys. However, in the process of warm rolling magnesium alloy sheets, higher requirements are imposed on the control of process parameters, especially tension control, which directly affects the forming quality and production stability of the sheets.

[0003] During the warm rolling process of magnesium alloy sheets, in order to ensure flat sheet shape and thickness accuracy, a tension force (referred to as tension) is usually applied at both ends of the sheet to improve the uniformity of plastic deformation of the metal during rolling. The reasonable application of tension can effectively reduce surface defects of the sheet and improve the rolling yield. At present, the commonly used tension control means in the rolling of magnesium alloy sheets mainly rely on tension cylinders to achieve. This method has the characteristics of simple operation, flexible loading and unloading, and relatively high control accuracy. The existing warm rolling tension control technologies in China can be divided into two methods: indirect tension control and direct tension control. Indirect tension control measures the oil pressure in the rod chamber and the rodless chamber of the tension cylinder through an oil pressure sensor, and indirectly calculates the tension value using the relationship between oil pressure and tension; direct tension control directly measures the tension acting on the sheet through a tension sensor and realizes the stable adjustment of tension through a feedback control algorithm. These two methods meet the conventional rolling requirements to a certain extent, but there are still significant deficiencies in actual production.

[0004] The mechanical properties of magnesium alloys are extremely sensitive to temperature changes. With the increase of rolling temperature, the yield strength and tensile strength of magnesium alloy sheets decrease significantly, resulting in a decrease in their tolerance to tension fluctuations. If the tension is too small, the sheet is prone to uneven extension during rolling, and even adhesion to the rollers, affecting the surface quality; if the tension is too large, it may cause the sheet to narrow, or even break in extreme cases, seriously affecting production efficiency and yield. This problem is particularly prominent in the warm rolling process of thin-gauge magnesium alloy sheets (thickness less than 0.6 mm). In the warm rolling process, each rolling pass undergoes a dynamic speed change process of starting, accelerating, decelerating and stopping. In these dynamic change stages, traditional tension control methods often cause large tension fluctuations due to slow response speed or insufficient adjustment accuracy. For example, indirect tension control relies on oil pressure calculation, which has problems of measurement lag and error accumulation; while direct tension control can monitor tension in real time, it lacks optimization of dynamic oil pressure regulation and is difficult to adapt to tension mutations caused by speed changes.

[0005] In the existing technology, the solutions to tension fluctuations are mostly focused on single feedback control or simple feedforward compensation. For example, by increasing the monitoring points of the oil pressure sensor or optimizing the parameters of the feedback controller, the tension fluctuation can be reduced to a certain extent, but it is still insufficient for the high-precision requirements of thin-gauge plates. In addition, in the traditional tension cylinder design, the friction resistance of the piston and the seal is large, which can easily cause oil pressure instability during the dynamic process, further exacerbating the tension fluctuation. These problems are manifested in production practice as frequent defects such as narrowing and belt breaking, especially for ultra-thin plates below 0.6 mm. The low yield rate and limited production efficiency have become bottlenecks restricting the development of magnesium alloy warm rolling technology. Summary of the invention

[0006] In view of this, the purpose of the present invention is to overcome the shortcomings of the prior art and provide a dynamic tension control device and method for warm rolling of magnesium alloy plates to achieve high-precision dynamic tension control and solve the problems of adhesion, narrowing and strip breakage of thin-gauge magnesium alloy plates caused by tension fluctuations during warm rolling.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A dynamic tension control device for warm rolling of a magnesium alloy plate, comprising a dynamic tension control mechanism arranged at both ends of the magnesium alloy plate, the dynamic tension control mechanism comprising a tension cylinder, a hydraulic servo control valve station, a PLC controller, a tension sensor, a hydraulic pressure sensor and a clamp;

[0009] The oil pressure servo control valve platform is connected to the tension oil cylinder through a tension cylinder oil pipe. The piston rod of the tension oil cylinder is connected to the clamp through a tension sensor. The clamp clamps the end of the magnesium alloy plate, and the tension acting on the magnesium alloy plate is directly measured through the tension sensor. The oil pressure sensor is arranged on the oil pressure servo control valve platform and is used to monitor the oil pressure in the rod chamber of the tension oil cylinder.

[0010] The oil pressure servo control valve platform, the tension sensor, and the oil pressure sensor are all connected to the PLC controller. The PLC controller dynamically adjusts the tension according to the data fed back by the tension sensor and the oil pressure sensor.

[0011] Furthermore, the oil pressure servo control valve platform includes a servo valve, an electromagnetic directional valve, an electromagnetic overflow valve, an electromagnetic ball valve, and an accumulator.

[0012] The electromagnetic directional valve is provided with four interfaces A, B, P, and T. The A interface of the electromagnetic directional valve is connected to the rod chamber of the tension oil cylinder through a first high-pressure ball valve. The B interface of the electromagnetic directional valve is connected to the rodless chamber of the tension oil cylinder. The P interface of the electromagnetic directional valve is sequentially connected to the servo valve, a first check valve, a filter, and a first high-pressure ball valve, and the first high-pressure ball valve is connected to the hydraulic oil input end. The T interface of the electromagnetic directional valve is connected to a second check valve, and the second check valve is connected to the hydraulic oil return end.

[0013] One end of the electromagnetic overflow valve is connected to the connecting pipeline between the electromagnetic directional valve and the servo valve, and the other end is connected to the second check valve.

[0014] The accumulator is arranged on the connecting pipeline between the servo valve and the first check valve, and this position is also connected to the connecting pipeline between the electromagnetic overflow valve and the second check valve through a second high-pressure ball valve. Another interface of the servo valve is connected to the connecting pipeline between the electromagnetic overflow valve and the second check valve. The B interface of the electromagnetic directional valve is also connected to the connecting pipeline between the electromagnetic directional valve and the second check valve through the electromagnetic ball valve.

[0015] The oil pressure sensor is arranged at one end of the electromagnetic overflow valve close to the servo valve.

[0016] Furthermore, a first pressure measuring joint is arranged at the connection point between the electromagnetic overflow valve and the electromagnetic directional valve and the servo valve. A second pressure measuring joint is arranged on the connecting pipeline of the T interface of the electromagnetic directional valve. A third pressure measuring joint is arranged on the connecting pipeline between the first check valve and the servo valve. The first pressure measuring joint, the second pressure measuring joint, and the third pressure measuring joint are connected to a pressure gauge through a pressure measuring hose.

[0017] Furthermore, the oil return ends of the dynamic tension control mechanisms at both ends of the magnesium alloy plate are communicated.

[0018] Further, the PLC controller includes a flow feedforward control module. The flow feedforward control module uses the current running speed of the magnesium alloy sheet as a reference variable, calculates the required oil inlet flow rate of the rod chamber of the tension cylinder through model calculation, and predicts the opening degree of the servo valve according to the oil inlet flow rate to pre-control the oil pressure in the rod chamber.

[0019] Further, the PLC controller further includes an inertia and friction compensation module. During the acceleration and deceleration process, the inertia and friction compensation module calculates the oil pressure compensation amount according to the inertia and friction model of the piston of the tension cylinder, and superimposes the oil pressure compensation amount on the oil pressure set value.

[0020] A dynamic tension control method for warm rolling of magnesium alloy sheets uses the above-mentioned dynamic tension control device for warm rolling of magnesium alloy sheets to dynamically control the tension during the warm rolling process of magnesium alloy sheets. The control method includes the following steps:

[0021] Place the magnesium alloy sheet between the rolling rolls and the tension cylinder, and clamp both ends of the magnesium alloy sheet with a clamp;

[0022] Start rolling, directly measure the tension acting on the magnesium alloy sheet through a tension sensor, and detect the oil pressure in the rod chamber of the tension cylinder through an oil pressure sensor;

[0023] Adopt a double closed-loop control strategy. The double closed-loop regulation control includes an outer loop feedback control and an inner loop feedback control. The outer loop feedback control uses the deviation between the actual tension value detected by the tension sensor and the tension set value as an input signal, and outputs it to the inner loop oil pressure set value after calculation by a proportional-integral regulator; the inner loop feedback control uses the deviation between the actual oil pressure value in the rod chamber detected by the oil pressure sensor and the oil pressure set value as an input signal, and outputs a servo valve opening degree control variable after calculation by a proportional-integral regulator.

[0024] During the acceleration and deceleration process, predict the opening degree of the servo valve through flow feedforward control, and calculate the oil pressure compensation amount through the inertia and friction compensation model to improve the dynamic tension control accuracy.

[0025] Further, the flow feedforward control is as follows: using the current running speed of the magnesium alloy sheet as a reference variable, calculate the required oil inlet flow rate Q of the rod chamber of the tension cylinder. The calculation formula is:

[0026] Q = kvS

[0027] Where k is a constant; v is the running speed of the piston of the tension cylinder, which is equal to the running speed of the sheet; S is the piston area of the rod chamber;

[0028] Calculate the opening degree A of the servo valve according to the oil inlet flow rate Q. The formula is:

[0029]

[0030] Among them, Q N is the rated output flow of the servo valve, and △P N is the rated pressure drop of the servo valve, and △P is the actual pressure drop.

[0031] Furthermore, the inertia and friction compensation are as follows: According to the mass m and acceleration a of the piston of the tension cylinder and the clamp, the inertia compensation amount F is calculated. The formula is:

[0032] F = m × a

[0033] And according to the actual measured values, the friction compensation curve is fitted to perform non - linear compensation on the tension.

[0034] The beneficial effects of the present invention are as follows:

[0035] The warm rolling dynamic tension control device and method for magnesium alloy sheets of the present invention have significant advantages over the prior art in terms of tension control accuracy, dynamic response ability, and production stability. The specific beneficial effects are as follows:

[0036] 1. High - precision tension control and optimized cylinder design

[0037] The present invention uses a servo - tension cylinder to achieve tension control. The cylinder is designed and manufactured according to the servo - cylinder standard, and a low - resistance sealing technology is selected, effectively reducing the frictional resistance between the piston and the seal. According to the required tension range during the warm rolling process of magnesium alloy sheets, the cross - sectional area design of the cylinder piston and the piston rod is optimized, enabling the oil pressure to stably operate above 1.5 MPa. This design avoids the problem of unstable control caused by insufficient pressure when the traditional tension cylinder operates in the low - oil - pressure region (usually less than 1.5 MPa). By increasing the oil - pressure operating range, the cylinder can more accurately respond to the adjustment instructions of the servo valve, thus significantly improving the stability and accuracy of tension control and providing a reliable hardware basis for the rolling of thin - gauge magnesium alloy sheets.

[0038] 2. Efficient oil - pressure servo control system

[0039] The oil - pressure control of the tension cylinder of the present invention is achieved by using a high - precision servo valve. The oil - pressure servo control valve platform consists of key components such as a filter, an accumulator, an electromagnetic directional valve, a servo valve, an electromagnetic relief valve, and an electromagnetic ball valve, forming an efficient hydraulic control system. In the tension control mode, the pressure in the rod - end chamber of the tension cylinder is precisely adjusted by the servo valve, while the non - rod - end chamber is connected to the return - oil pipeline through a large - flow electromagnetic ball valve to ensure the smooth outflow of hydraulic oil and avoid pressure retention. At the same time, the return - oil pipelines of the left and right tension cylinders are connected together, enabling the hydraulic oil to circulate between the non - rod - end chambers of the two tension cylinders along the shortest path. This design not only improves the response speed of the hydraulic system but also reduces the pressure loss in the oil circuit, thereby enhancing the dynamic performance of tension adjustment and providing a guarantee for solving the problems of sheet adhesion and narrowing.

[0040] 3. Advanced Double-Closed-Loop Control Strategy

[0041] The present invention adopts a double-closed-loop control strategy, which combines the outer-loop feedback control detected by the tension sensor and the inner-loop feedback control detected by the oil pressure sensor, significantly improving the accuracy and stability of tension regulation. The outer-loop feedback control takes the deviation between the tension set value and the actual value as the input signal, and after calculation by the proportional-integral regulator, it outputs to the inner-loop oil pressure set value, effectively reducing the overshoot in the tension regulation process. The inner-loop feedback control takes the deviation between the set value and the actual value of the oil pressure in the rod chamber of the tension cylinder as the input signal, and calculates the opening control variable of the servo valve through the proportional-integral regulator to achieve a rapid response to the oil pressure. This control method of coordinated operation of the inner and outer loops can quickly adjust the tension when the sheet speed changes dynamically (such as starting, accelerating, decelerating), avoiding the tension fluctuation problem caused by the response lag of the traditional single feedback control, thus significantly reducing the occurrence of narrow drawing and tape breakage phenomena.

[0042] 4. Flow Feedforward Control to Improve Dynamic Response Ability

[0043] In response to the dynamic change of the sheet speed during the warm rolling process, the present invention integrates a flow feedforward control module in the PLC controller. This module takes the running speed of the current magnesium alloy sheet as a reference variable, calculates the oil inlet flow required for the rod chamber of the tension cylinder through a mathematical model (Q = k×v×S), and predicts the opening of the servo valve according to the flow value calculation formula to pre-control the oil pressure in the rod chamber. This feedforward control method can actively adjust the oil pressure before the speed change occurs, avoiding the sudden change of tension caused by the lag adjustment in the traditional feedback control, thus significantly improving the response speed and stability of the dynamic tension control, especially suitable for the high-speed rolling requirements of thin-gauge sheets.

[0044] 5. Inertia and Friction Compensation to Optimize Dynamic Performance

[0045] The present invention also introduces an inertia and friction compensation module in the PLC controller to optimize the motion characteristics of the piston of the tension cylinder during the acceleration and deceleration processes. During the acceleration and deceleration stages, according to the mass m and acceleration a of the piston of the tension cylinder and the clamp, the inertia compensation amount F is calculated, and combined with the friction compensation curve fitted by the actual measurement value, non-linear compensation is performed on the tension. This compensation mechanism effectively cancels the influence of the inertial force and friction force in the piston movement on the oil pressure, enabling the tension to remain stable during the dynamic process and avoiding the tension fluctuation caused by inertia or friction. This design is particularly suitable for the warm rolling of thin-gauge magnesium alloy sheets, which can significantly reduce the risk of tape breakage and improve the reliability of the production process.

[0046] 6. Comprehensive Performance Improvement and Production Efficiency

[0047] Through the comprehensive application of multiple technologies such as low-resistance sealed servo tension cylinder, direct tension control strategy, dual feedback closed-loop control, flow feedforward control and inertia friction compensation, the dynamic tension control accuracy of the present invention is improved from ±5.0% of traditional technology to ±2.5%. This accuracy improvement effectively solves the adhesion, narrowing and even tearing caused by tension fluctuations in thin-gauge magnesium alloy sheets (especially products with a thickness of less than 0.6 mm) during warm rolling. In actual production, the device significantly improves the yield rate and reduces downtime and material waste caused by broken strips, thereby improving production efficiency and economic benefits. At the same time, the stable operation of the device also provides technical support for the industrial production of magnesium alloy sheets, and has broad application prospects.

[0048] In summary, the present invention comprehensively improves the dynamic tension control capability during the warm rolling process of magnesium alloy plates through the optimization of hardware design and the innovation of control strategy. It not only solves the shortcomings of the existing technology, but also significantly improves the production quality and efficiency of thin-gauge plates, laying the foundation for the further development of magnesium alloy warm rolling technology.

[0049] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0051] Figure 1 This is a schematic diagram of the installation of the dynamic tension control device for warm rolling of magnesium alloy plates in the present invention.

[0052] Figure 2 It is a schematic diagram of the oil pressure servo control valve station in the present invention.

[0053] Figure 3 It is a flow chart of dynamic tension control in the present invention.

[0054] Reference numerals: 1 - roll; 2 - magnesium alloy sheet; 3 - tension cylinder oil pipe; 4 - oil pressure servo control valve platform; 5 - tension cylinder; 6 - tension sensor; 11 - clamp; 1.1 - first high - pressure ball valve; 2.1 - filter; 3.1 - first check valve; 4.1 - accumulator; 5.1 - first pressure measuring joint; 5.2 - second pressure measuring joint; 5.3 - third pressure measuring joint; 6.1 - pressure measuring hose; 7.1 - pressure gauge; 8.1 - servo valve; 9.1 - oil pressure sensor; 10.1 - electromagnetic relief valve; 11.1 - electromagnetic directional valve; 12.1 - second check valve; 13 - second high - pressure ball valve; 15 - electromagnetic ball valve. Detailed implementation manners

[0055] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only schematically illustrate the basic concept of the present invention. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0056] Among them, the drawings are only for exemplary illustration, showing only schematic diagrams, not physical diagrams, and cannot be understood as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well - known structures and their descriptions in the drawings may be omitted.

[0057] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for exemplary illustration and cannot be understood as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0058] The following describes in detail the warm rolling dynamic tension control device and method for magnesium alloy sheets of the present invention through two specific embodiments to further clarify the technical solution and its implementation manner of the present invention.

[0059] Embodiment 1: Bidirectional warm rolling control of magnesium alloy sheets with a thickness of 0.8 mm

[0060] This embodiment provides a warm rolling dynamic tension control device for magnesium alloy sheets, as Figure 1 shown. The device includes dynamic tension control mechanisms provided at both ends of the magnesium alloy sheet 2. Each side's dynamic tension control mechanism includes a tension oil cylinder 5, an oil pressure servo control valve platform 4, a PLC controller, a tension sensor 6, an oil pressure sensor 9.1, and a clamp 11.

[0061] The tension oil cylinder 5 is connected to the oil pressure servo control valve platform 4 through a tension cylinder oil pipe 3. Its piston rod is connected to the clamp 11 through the tension sensor 6, and the clamp 11 holds the end of the magnesium alloy sheet 2. The tension sensor 6 is used to directly measure the tension acting on the magnesium alloy sheet 2. The oil pressure sensor 9.1 is installed on the oil pressure servo control valve platform 4 to monitor the oil pressure in the rod chamber of the tension oil cylinder 5. The oil pressure servo control valve platform 4, the tension sensor 6, and the oil pressure sensor 9.1 are all electrically connected to the PLC controller, and the PLC controller dynamically adjusts the tension according to the feedback data.

[0062] As Figure 2 shown, the specific structure of the oil pressure servo control valve platform 4 includes a servo valve 8.1, an electromagnetic directional valve 11.1, an electromagnetic overflow valve 10.1, an electromagnetic ball valve 15, and an accumulator 4.1. The electromagnetic directional valve 11.1 has four interfaces A, B, P, and T. Among them, the A interface is connected to the rod chamber of the tension oil cylinder 5 through a first high-pressure ball valve 1.1, the B interface is connected to the rodless chamber, the P interface is sequentially connected to the servo valve 8.1, a first one-way valve 3.1, a filter 2.1, and the first high-pressure ball valve 1.1, and the first high-pressure ball valve 1.1 accesses the hydraulic oil input end; the T interface is connected to the hydraulic oil return end through a second one-way valve 12.1. One end of the electromagnetic overflow valve 10.1 is connected to the pipeline between the electromagnetic directional valve 11.1 and the servo valve 8.1, and the other end is connected to the second one-way valve 12.1. The accumulator 4.1 is provided between the servo valve 8.1 and the first one-way valve 3.1 and is communicated with the pipeline between the electromagnetic overflow valve 10.1 and the second one-way valve 12.1 through a second high-pressure ball valve 13. The electromagnetic ball valve 15 connects the B interface of the electromagnetic directional valve 11.1 to the pipeline between the electromagnetic overflow valve 10.1 and the second one-way valve 12.1. The oil pressure sensor 9.1 is located at one end of the electromagnetic overflow valve 10.1 close to the servo valve 8.1. To monitor the oil pressure, the device sets a first pressure measuring joint 5.1, a second pressure measuring joint 5.2, and a third pressure measuring joint 5.3 at key positions, which are respectively connected to a pressure gauge 7.1 through a pressure measuring hose 6.1. The oil return ends of the two sides' tension control mechanisms are connected.

[0063] The PLC controller is built-in with a flow feedforward control module and an inertia and friction compensation module for dynamically optimizing the tension control.

[0064] This embodiment aims at a magnesium alloy sheet with an initial thickness of 2.0 mm, which is targeted to be rolled to 0.8 mm, and adopts a two-way rolling process. The specific operation process is as follows:

[0065] Preparation stage: The magnesium alloy sheet 2 is placed between the roller 1 and the tension cylinder 5, and the roller gap of the roller 1 is closed to make the roller 1 in close contact with the magnesium alloy sheet 2. The clamps 11 clamp the two ends of the sheet respectively.

[0066] Tension input: The rod chamber of the left tension cylinder 5 establishes oil pressure through the servo valve 8.1 of the hydraulic servo control valve station 4. The oil pressure is preset to 2.0MPa according to the process table, and the tension setting value on the left is 10kN. The rod chamber of the right tension cylinder 5 also establishes 2.0MPa oil pressure, and the tension setting value on the right is 10kN. The tension cylinders 5 on both sides work together to tighten the plate.

[0067] Rolling to the right: Start rolling, the plate moves to the right, and the roller 1 presses down 0.2mm at a time. The pistons of the left and right tension cylinders 5 move to the right synchronously with the plate, and the tension sensor 6 detects the tension in real time. If the tension deviates from the set value, the PLC controller adjusts the opening of the servo valve 8.1 through double closed-loop control. The outer ring outputs the oil pressure set value based on the tension deviation through the proportional integral algorithm, and the inner ring adjusts the oil pressure to 2.0MPa based on the oil pressure deviation to keep the tension constant.

[0068] Direction change: After the plate is rolled to the tail, the machine stops and changes direction to roll to the left. The pistons of the left and right tension cylinders 5 move to the left synchronously, and the tension remains unchanged at 10kN.

[0069] Dynamic adjustment: During the acceleration and deceleration phase, the flow feedforward control module calculates the oil flow Q (Q = k × v × S) based on the plate speed (e.g. 1 m / s) and predicts the servo valve opening degree 8.1; the inertia and friction compensation ... piston mass (10 kg) and acceleration (0.5 m / s 2 ) Calculate the compensation amount F (F=5N) and add it to the oil pressure setting value.

[0070] Repeated rolling: Roll back and forth until the plate thickness reaches 0.8mm, then stop and unload.

[0071] like Figure 3 As shown, in this embodiment, through double closed-loop control and feed-forward compensation, the tension fluctuation is controlled within ±2.5%, thereby avoiding the phenomenon of plate narrowing and belt breaking, and the yield rate reaches 98%.

[0072] Example 2: Unidirectional warm rolling control of ultra-thin magnesium alloy sheet with a thickness of 0.5 mm

[0073] The device structure of this embodiment is basically the same as that of embodiment 1. Figure 1As shown, it includes tension cylinders 5, an oil pressure servo control valve platform 4, a PLC controller, a tension sensor 6, an oil pressure sensor 9.1, and clamps 11 provided at both ends of the magnesium alloy sheet 2. The difference is that, in view of the characteristics of the ultra-thin sheet (thickness 0.5 mm), the piston cross-sectional area of the tension cylinder 5 is reduced to 50 cm 2 , so as to improve the oil pressure sensitivity; the servo valve 8.1 is selected with a higher response frequency model (rated flow rate 50 L / min).

[0074] The hydraulic circuit of the oil pressure servo control valve platform 4 is as shown in Figure 2 . The A, B, P, and T ports of the electromagnetic directional valve 11.1 are respectively connected to the rod chamber and the non-rod chamber of the tension cylinder 5, the hydraulic oil input end, and the oil return end. The capacity of the accumulator 4.1 is increased to 2 L to buffer the pressure fluctuation. The pressure measuring joints 5.1, 5.2, and 5.3 are connected to the pressure gauge 7.1 through the pressure measuring hose 6.1 to monitor the oil circuit state in real time. The oil return ends on both sides are connected, and the oil circuit circulation efficiency is higher.

[0075] In this embodiment, for the magnesium alloy sheet with an initial thickness of 1.2 mm and the target rolling to 0.5 mm, the unidirectional rolling process is adopted, and the specific process is as follows:

[0076] Preparation stage: Place the magnesium alloy sheet 2 between the rolling mill 1 and the tension cylinder 5, close the roll gap, and the clamps 11 clamp both ends of the sheet.

[0077] Tension input: The oil pressure in the rod chamber of the left tension cylinder 5 is set to 1.8 MPa, the tension set value is 8 kN, and it is controlled by the servo valve 8.1; the oil pressure in the rod chamber of the right tension cylinder 5 is set to 1.8 MPa, and the tension set value is 8 kN. The sheet is tightened to the initial state.

[0078] Unidirectional rolling: Start rolling, the sheet moves to the right, and the single pass reduction of the rolling mill 1 is 0.1 mm. The pistons of the left and right tension cylinders 5 move synchronously to the right, and the tension sensor 6 detects the tension change. The PLC controller adopts a double closed-loop control. The outer loop adjusts the tension to 8 kN, and the inner loop feedback adjusts the opening degree of the servo valve 8.1 through the oil pressure sensor 9.1 to maintain the oil pressure stability.

[0079] Dynamic optimization: In the acceleration stage (the speed rises from 0 to 0.2 m / s), the flow feedforward module calculates the inlet oil flow rate Q and predicts the opening degree A; in the deceleration stage (the speed drops to 0), the inertia compensation amount F (based on the piston mass of 90 kg and the acceleration of 0.1 m / s 2 , F = 9 N) is superimposed on the oil pressure set value to ensure the tension is stable.

[0080] Completion of rolling: After unidirectional rolling to a thickness of 0.5 mm, stop the machine, loosen the clamps 11 and remove the sheet.

[0081] In this embodiment, the parameters of the oil cylinder and the servo valve are optimized for ultra-thin plates, the tension fluctuation is controlled within ±1.0%, there is no adhesion or tape breakage phenomenon, the thickness of the finished product is uniform, and the production efficiency is increased by 20%.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A dynamic tension control device for warm rolling of magnesium alloy sheets, characterized in that: It includes a dynamic tension control mechanism arranged at both ends of the magnesium alloy plate, and the dynamic tension control mechanism includes a tension cylinder, a hydraulic servo control valve station, a PLC controller, a tension sensor, a hydraulic sensor and a clamp; The oil pressure servo control valve station is connected to the tension oil cylinder through the tension cylinder oil pipe, the piston rod of the tension oil cylinder is connected to the clamp through the tension sensor, the clamp is clamped at the end of the magnesium alloy plate, and the tension acting on the magnesium alloy plate is directly measured by the tension sensor; the oil pressure sensor is arranged on the oil pressure servo control valve station, and is used to monitor the oil pressure of the rod chamber of the tension oil cylinder; The oil pressure servo control valve station, the tension sensor and the oil pressure sensor are all connected to the PLC controller, and the PLC controller dynamically adjusts the tension according to the data fed back by the tension sensor and the oil pressure sensor.

2. The dynamic tension control device for warm rolling of magnesium alloy sheet according to claim 1, characterized in that: The oil pressure servo control valve station includes a servo valve, an electromagnetic reversing valve, an electromagnetic overflow valve, an electromagnetic ball valve and an accumulator; The electromagnetic reversing valve is provided with four interfaces, namely, A, B, P and T. The A interface of the electromagnetic reversing valve is connected to the rod chamber of the tension oil cylinder via the first high-pressure ball valve, the B interface of the electromagnetic reversing valve is connected to the rodless chamber of the tension oil cylinder, the P interface of the electromagnetic reversing valve is connected to the servo valve, the first check valve, the filter and the first high-pressure ball valve in sequence, and the first high-pressure ball valve is connected to the hydraulic oil input end; the T interface of the electromagnetic reversing valve is connected to the second check valve, and the second check valve is connected to the hydraulic oil return end; One end of the electromagnetic overflow valve is connected to the connecting pipeline between the electromagnetic reversing valve and the servo valve, and the other end is connected to the second one-way valve; The accumulator is arranged on the connecting pipeline between the servo valve and the first one-way valve, and this position is also connected to the connecting pipeline between the electromagnetic overflow valve and the second one-way valve through the second high-pressure ball valve; another interface of the servo valve is connected to the connecting pipeline between the electromagnetic overflow valve and the second one-way valve; the B interface of the electromagnetic reversing valve is also connected to the connecting pipeline between the electromagnetic reversing valve and the second one-way valve through the electromagnetic ball valve; The oil pressure sensor is arranged at one end of the electromagnetic overflow valve close to the servo valve.

3. The dynamic tension control device for warm rolling of magnesium alloy sheet according to claim 2, characterized in that: A first pressure measuring joint is provided at the connection point between the electromagnetic overflow valve, the electromagnetic reversing valve and the servo valve, a second pressure measuring joint is provided on the connecting pipeline of the T interface of the electromagnetic reversing valve, and a third pressure measuring joint is provided on the connecting pipeline between the first one-way valve and the servo valve. The first pressure measuring joint, the second pressure measuring joint and the third pressure measuring joint are connected to a pressure gauge through a pressure measuring hose.

4. The dynamic tension control device for warm rolling of magnesium alloy sheet according to claim 2, characterized in that: The oil return ends of the dynamic tension control mechanisms at both ends of the magnesium alloy plate are connected.

5. The dynamic tension control device for warm rolling of magnesium alloy sheet according to claim 1, characterized in that: The PLC controller includes a flow feedforward control module, which uses the current running speed of the magnesium alloy plate as a reference variable, calculates the required oil inlet flow of the rod chamber of the tension cylinder through a model, predicts the opening degree of the servo valve based on the oil inlet flow, and pre-controls the oil pressure of the rod chamber.

6. The dynamic tension control device for warm rolling of magnesium alloy sheet according to claim 5, characterized in that: The PLC controller also includes an inertia and friction compensation module, which calculates the oil pressure compensation amount according to the inertia and friction model of the tension cylinder piston during acceleration and deceleration, and adds the oil pressure compensation amount to the oil pressure setting value.

7. A method for controlling dynamic tension of warm rolling of magnesium alloy sheet, characterized in that: The dynamic tension control device for warm rolling of a magnesium alloy sheet according to any one of claims 1 to 6 is used to dynamically control the tension of the magnesium alloy sheet during the warm rolling process. The control method comprises the following steps: Placing the magnesium alloy sheet between the roller and the tension cylinder, and clamping both ends of the magnesium alloy sheet by clamps; When rolling is started, the tension acting on the magnesium alloy sheet is directly measured by the tension sensor, and the oil pressure in the rod chamber of the tension cylinder is detected by the oil pressure sensor; A double closed-loop control strategy is adopted, and the double closed-loop regulation control includes an outer loop feedback control and an inner loop feedback control. The outer loop feedback control uses the deviation between the actual tension value detected by the tension sensor and the tension setting value as an input signal, which is calculated by a proportional-integral regulator and output to the inner loop oil pressure setting value; the inner loop feedback control uses the deviation between the actual rod chamber oil pressure value detected by the oil pressure sensor and the oil pressure setting value as an input signal, which is calculated by a proportional-integral regulator and output to the servo valve opening control variable; During the acceleration and deceleration process, the servo valve opening is predicted through flow feedforward control, and the oil pressure compensation amount is calculated through the inertia and friction compensation model to improve the dynamic tension control accuracy.

8. The method for controlling dynamic tension of warm rolling of magnesium alloy sheet according to claim 7, characterized in that: The flow feedforward control is: taking the current running speed of the magnesium alloy plate as the reference variable, the required oil inlet flow Q of the rod chamber of the tension cylinder is calculated. The calculation formula is: Q=kvS Among them, k is a constant; v is the running speed of the tension cylinder piston, which is equal to the running speed of the plate; S is the area of ​​the rod chamber piston; The servo valve opening degree A is calculated based on the oil inlet flow rate Q. The formula is: Among them, Q N is the rated output flow of the servo valve, △P N is the rated pressure drop of the servo valve, and △P is the actual pressure drop.

9. The method for controlling dynamic tension of warm rolling of magnesium alloy sheet according to claim 8, characterized in that: Inertia and friction compensation: According to the mass m and acceleration a of the tension cylinder piston and the clamp, the inertia compensation F is calculated using the formula: F=m×a And the friction compensation curve is fitted according to the actual measured value to perform nonlinear compensation for the tension.

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