Hydraulic proportional balance control loop for mandrel support frame of mandrel pipe mill

Abstract

The invention discloses a mandrel pipe mill mandrel support frame hydraulic proportional balance control loop, which relates to the technical field of mandrel pipe mills, and comprises a main oil inlet pipe, a main oil return pipe, a proportional control system and a balance control system which are connected in parallel between the main oil inlet pipe and the main oil return pipe and are respectively connected with an open cylinder and a closed cylinder, and opening, closing and core holding actions of the core rod supporting rack are cooperatively controlled. The proportional control system takes a closed-loop control proportional valve as a core, can adjust the speed of an open cylinder in a stepless manner, automatically decelerates to prevent impact when approaching a target stroke, and is matched with a hydraulic control one-way valve group to realize position locking; the balance control system adjusts the core holding force through a pressure reducing valve, adjusts the cylinder closing speed through a throttling valve, and an energy accumulator absorbs pressure impact and stabilizes pressure. During working, the two systems cooperate to realize stable actions of opening during rolling, closing after tube removal and resetting of a rack. The loop eliminates mechanical shock and noise, eliminates a turbine worm positioning mechanism, reduces faults, adapts to multiple working conditions, is convenient to operate and maintain, improves the operation reliability and prolongs the service life.

Description

Technical Field

[0001] This application belongs to the field of continuous rolling mills, and particularly relates to a hydraulic proportional balance control circuit for a mandrel support frame of a continuous rolling mill. Background Technology

[0002] Patent publication number CN102327899A discloses "a mandrel support device for a continuous tube rolling mill and a continuous tube rolling mill." The mandrel support frame uses a mechanical positioning-hydraulic opening and closing control mode: a worm gear reducer (with encoder) controls the opening degree of the mandrel support frame; an opening cylinder controls the opening action, and a closing cylinder performs the closing operation. When the opening cylinder extends to open, the closing cylinder simultaneously retracts for a reset movement; when the closing cylinder extends to close and support the mandrel, the opening cylinder simultaneously retracts for a reset movement. During rolling, multiple mandrel support frames open rapidly one by one to prevent steel accumulation and rolling jamming accidents; after tube removal, the mandrel support frame quickly closes to support the mandrel to prevent contact between the mandrel and the rolls, thus preventing roll damage.

[0003] The existing mandrel support frame structure is attached. Figure 1 Its disadvantages are: the mandrel support frame is controlled by a hydraulic switch valve, and once the speed is set, it cannot be controlled. Each time the opening cylinder moves, the positioning piston rod and the worm gear positioning block have a spatial distance. The rapid reset of the opening cylinder will generate a strong impact. The opening and closing cylinders of the mandrel support frame move in the same direction, and their speeds cannot be the same. This will generate a secondary impact on the worm gear and generate a large metal knocking noise. Long-term impact will cause the worm gear to fail and lose its positioning function. Summary of the Invention

[0004] To address some or all of the technical problems existing in the prior art, this application provides a hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill.

[0005] This application provides a hydraulic proportional balance control circuit for a mandrel support frame in a continuous rolling mill, including a main oil inlet pipe, a main oil return pipe, a proportional control system, and a balance control system. The balance control system and the proportional control system are connected in parallel between the main oil inlet pipe and the main oil return pipe. The balance control system is connected to a closing cylinder and is used to control the closing cylinder's action to achieve the mandrel support frame's core-holding action. The proportional control system is connected to an opening cylinder and is used to control the opening cylinder's action to achieve the opening and closing action of the mandrel support frame. Through the coordinated action of the proportional control system and the balance control system, stable operation control of the mandrel support frame is achieved.

[0006] Preferably, the balance control system includes an accumulator, a ball valve, a pressure reducing valve, a first safety valve, a first check valve, a throttle valve, and a first directional valve; The main oil inlet pipe is connected to the oil inlet of the first directional valve, the oil return port of the first directional valve is connected to the main oil return pipe, the first working oil port of the first directional valve is connected to the rod chamber of the closing cylinder, and the second working oil port of the first directional valve is connected to the rodless chamber of the closing cylinder. The pressure reducing valve and the first check valve are connected in series between the main oil outlet pipe and the oil inlet of the first directional valve, and the oil outlet of the first check valve is connected to the oil inlet of the first directional valve. The accumulator's inlet is connected to the main oil pipe branch on the oil inlet side of the first directional valve, and forms a parallel layout with the main oil pipe branch. The inlets of the accumulator, ball valve, and first safety valve are all connected to the same main oil pipe branch on the oil inlet side of the first directional valve, and the three are arranged in parallel on the main oil pipe branch. The outlets of the ball valve and the first safety valve are respectively connected to the main return oil pipe. The throttle valve is connected in series in the pipeline between the working oil port of the first directional valve and the closing cylinder.

[0007] Preferably, the proportional control system includes a first hydraulic check valve, a second hydraulic check valve, a third hydraulic check valve, a proportional valve, a second directional valve, a second safety valve, and a second check valve; The proportional valve's inlet is connected to the main inlet pipe, and the proportional valve's return port is connected to the main return pipe; the proportional valve's first working port is connected to the main inlet pipe of the second hydraulic check valve, and the proportional valve's second working port is connected to the main inlet pipe of the third hydraulic check valve. The first hydraulic check valve is connected in series between the main oil outlet pipe and the oil inlet of the proportional valve, and the main oil inlet of the first hydraulic check valve is connected to the main oil inlet pipe. The main outlet of the second hydraulic check valve is connected to the oil port of the rodless chamber of the open cylinder; The main oil outlet of the third hydraulic control check valve is connected to the oil port pipeline of the rod chamber of the open cylinder; The oil inlet of the second safety valve is connected to the pipeline corresponding to the main oil outlet of the second hydraulic check valve, and the second safety valve is connected in parallel to the pipeline corresponding to the rodless chamber oil port of the open cylinder. The oil outlet of the second safety valve is connected to the pipeline corresponding to the return oil port of the proportional valve. The oil inlet of the second check valve is connected to the pipeline corresponding to the main oil outlet of the third hydraulic check valve, and the second check valve is connected in parallel to the pipeline corresponding to the rod chamber oil port of the open cylinder. The oil outlet of the second check valve is connected to the pipeline corresponding to the return oil port of the proportional valve. The oil inlet of the second directional valve is connected to the main oil inlet pipe, the oil return port of the second directional valve is connected to the main oil return pipe, and the working oil port of the second directional valve is connected in parallel with the first hydraulic check valve, the second hydraulic check valve and the third hydraulic check valve through oil pipes respectively.

[0008] Preferably, the first directional valve has two control ports, YA and YB; when YA is energized, constant pressure oil is introduced into the rodless chamber of the closing cylinder, and the closing cylinder remains in the extended state; when YB is energized, oil returns to the rodless chamber of the closing cylinder, and the closing cylinder retracts.

[0009] Preferably, when the second directional valve is energized, the first hydraulic check valve, the second hydraulic check valve, and the third hydraulic check valve open, and the proportional valve can drive the opening cylinder to move; when the second directional valve is de-energized, the first hydraulic check valve, the second hydraulic check valve, and the third hydraulic check valve close, and the position of the opening cylinder is locked.

[0010] Preferably, the proportional valve adopts a closed-loop automatic control principle to enable the open cylinder to extend and retract rapidly while automatically decelerating when approaching the target stroke, thus avoiding hydraulic shock.

[0011] Preferably, the accumulator is used to absorb the hydraulic shock generated when the open cylinder is activated, thereby stabilizing the pressure of the balance control system.

[0012] Preferably, the output pressure of the pressure reducing valve is adjustable and used to set the core clamping force of the closing cylinder.

[0013] Preferably, the throttle valve is used to regulate the extension and retraction speed of the closing cylinder.

[0014] The hydraulic proportional balance control circuit for the mandrel support frame of the continuous rolling mill in this application has the following advantages and positive effects: (1) The proportional control system uses a proportional valve with a closed-loop automatic control design as its core control component. The reasonable pipeline layout of its oil inlet, oil return, and working oil inlet allows the proportional valve to directly regulate the amount of oil entering the two chambers of the opening cylinder. This proportional valve can continuously adjust the flow output of the working oil inlet according to the input signal, realizing stepless control of the extension and retraction speed of the opening cylinder. Especially when the opening cylinder approaches the target stroke, it can automatically reduce the flow to achieve deceleration, fundamentally avoiding rigid impact between the opening cylinder and related mechanical structures, reducing wear and deformation of the mechanical structures caused by impact, and extending the service life of the mandrel support frame and hydraulic actuators. This makes the opening and closing action of the mandrel support frame more in line with the rolling process's requirements for action accuracy, providing a basic guarantee for the stable support of the mandrel.

[0015] In the proportional control system, three hydraulically controlled check valves and a second directional valve form a coordinated bidirectional pressure-holding and unlocking mechanism. The first hydraulically controlled check valve ensures stable pressure in the inlet pipeline, while the second and third hydraulically controlled check valves respectively lock the oil state in the rodless and rod-side chambers of the open cylinder, preventing displacement of the open cylinder due to pipeline leakage. Centralized control is achieved by energizing and de-energizing the second directional valve. When energized, the main oil circuit is opened to ensure action execution; when de-energized, the main oil circuit is closed to lock the position of the open cylinder. This allows the open cylinder to maintain a stable opening degree when stopped or in standby mode, eliminating the need for additional mechanical positioning structures such as worm gears. This not only simplifies the overall equipment layout but also completely eliminates problems such as decreased positioning accuracy and positioning failure caused by component wear in traditional mechanical positioning modes, improving the reliability of the mandrel support frame's position holding.

[0016] The balance control system, designed to meet the core-clamping action requirements of the mandrel support frame, incorporates a pressure and speed regulation circuit consisting of a pressure reducing valve and a throttle valve. The pressure reducing valve stably outputs oil at a set pressure, providing a continuous and stable core-clamping force to the closing cylinder. This ensures the mandrel support frame's holding effect on the mandrel remains reliable, preventing mandrel support misalignment due to fluctuations in core-clamping force, which could affect rolling accuracy. The throttle valve, connected in series in the pipeline between the first directional valve and the closing cylinder, allows for flexible adjustment of the closing cylinder's extension and retraction speed according to process requirements, ensuring a good match between the core-clamping action speed and the opening and closing speed of the opening cylinder.

[0017] In the balance control system, the accumulator connected in parallel to the main oil pipe branch plays a crucial role in absorbing shocks. When the proportional control system drives the open cylinder to move rapidly, causing system pressure fluctuations, the accumulator can absorb the pressure peak through its own expansion. Simultaneously, it releases oil to replenish the oil circuit when the pressure drops, effectively smoothing out pressure fluctuations throughout the hydraulic system. This not only ensures the continuous stability of the mandrel clamping state in the balance control system, preventing pressure fluctuations from interfering with the clamping effect, but also achieves seamless coordination between the proportional and balance control systems. This ensures that the opening and closing actions of the open cylinder and the clamping action of the closed cylinder are always synchronized, completely solving problems such as mechanical collisions and metal-on-metal impacts caused by asynchronous bidirectional actions in traditional systems, and improving the overall stability of the mandrel support system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for further understanding of the embodiments of this application and constitute a part of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the existing mandrel support frame structure; Figure 2 This is a schematic diagram of the hydraulic cylinder arrangement of the mandrel support frame structure in this application; Figure 3 This is a schematic diagram of the proportional composite balance control hydraulic system of this application.

[0019] Explanation of reference numerals in the attached figures: 1-Frame body, 2-Mandrel support frame, 3-Closed cylinder, 4-Swing frame, 5-Open cylinder, 6-Mandrel roller, 7-Wercer reducer, 8-Accumulator, 9-Ball valve, 10-Pressure reducing valve, 11-First safety valve, 12-First check valve, 13-Throttle valve, 14-First directional valve, 15-First hydraulic check valve, 16-Second hydraulic check valve, 17-Third hydraulic check valve, 18-Proportional valve, 19-Second directional valve, 20-Second safety valve, 21-Second check valve. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0021] The mandrel support frame of a continuous rolling mill includes the frame body 1, the mandrel support frame 2, the closing cylinder 3, the swing frame 4, and the opening cylinder 5. For example... Figure 1 As shown, the existing mandrel support frame of the continuous rolling mill uses a worm gear reducer 7 to control the opening degree setting of the mandrel support frame 2.

[0022] like Figure 2 and Figure 3 As shown, the hydraulic proportional balance control circuit of the mandrel support frame in this embodiment includes a main oil inlet pipe, a main oil return pipe, a proportional control system, and a balance control system. The balance control system and the proportional control system are connected in parallel between the main oil inlet pipe and the main oil return pipe. The balance control system is connected to the closing cylinder 3 and is used to control the action of the closing cylinder 3 to realize the mandrel support frame 2's mandrel clamping action. The proportional control system is connected to the opening cylinder 5 and is used to control the action of the opening cylinder 5 to realize the opening and closing action of the mandrel support frame 2. Through the coordinated action of the proportional control system and the balance control system, the stable action control of the mandrel support frame 2 is achieved.

[0023] The balance control system includes an accumulator 8, a ball valve 9, a pressure reducing valve 10, a first safety valve 11, a first check valve 12, a throttle valve 13, and a first directional valve 14.

[0024] The main oil inlet pipe is connected to the oil inlet of the first directional valve 14, the oil return port of the first directional valve 14 is connected to the main oil return pipe, the first working oil port of the first directional valve 14 is connected to the rod chamber of the closing cylinder 3, and the second working oil port of the first directional valve 14 is connected to the rodless chamber of the closing cylinder 3; the pressure reducing valve 10 and the first check valve 12 are connected in series between the main oil outlet pipe and the oil inlet of the first directional valve 14, and the oil outlet of the first check valve 12 is connected to the oil inlet of the first directional valve 14; the oil inlet of the accumulator 8 is connected to... The main oil pipe branch line on the oil inlet side of the first directional valve 14 is connected and forms a parallel layout with the main oil pipe branch line. The oil inlets of the accumulator 8, ball valve 9, and first safety valve 11 are all connected to the same main oil pipe branch line on the oil inlet side of the first directional valve 14. The three are arranged in parallel on the main oil pipe branch line. The oil outlet of the ball valve 9 and the oil outlet of the first safety valve 11 are respectively connected to the main return oil pipe line. The throttle valve 13 is connected in series in the pipeline between the working oil port of the first directional valve 14 and the closing cylinder 3.

[0025] The first directional valve 14 has two control ports, Y1A and Y1B. When Y1A is energized, constant pressure oil is introduced into the rodless chamber of the closing cylinder 3, and the closing cylinder 3 remains in the extended state. When Y1B is energized, oil returns to the rodless chamber of the closing cylinder 3, and the closing cylinder 3 retracts.

[0026] The output pressure of the pressure reducing valve 10 is adjustable and is used to set the core clamping force of the closing cylinder 3. The throttle valve 13 is used to adjust the extension and retraction speed of the closing cylinder 3.

[0027] The proportional control system includes a first hydraulic check valve 15, a second hydraulic check valve 16, a third hydraulic check valve 17, a proportional valve 18, a second directional valve 19, a second safety valve 20, and a second check valve 21.

[0028] The inlet of proportional valve 18 is connected to the main inlet pipe, and the return port of proportional valve 18 is connected to the main return pipe; the first working port of proportional valve 18 is connected to the main inlet pipe of the second hydraulic check valve 16, and the second working port of proportional valve 18 is connected to the main inlet pipe of the third hydraulic check valve 17; the first hydraulic check valve 15 is connected in series between the main outlet pipe and the inlet of proportional valve 18, and the main inlet of the first hydraulic check valve 15 is connected to the main inlet pipe; the main outlet of the second hydraulic check valve 16 is connected to the rodless chamber port of the open cylinder 5; the main outlet of the third hydraulic check valve 17 is connected to the rod chamber port of the open cylinder 5; the inlet of the second safety valve 20 is connected to the corresponding pipe of the main outlet of the second hydraulic check valve 16. The system is connected, and the second safety valve 20 is connected in parallel to the pipeline corresponding to the rodless chamber oil port of the open cylinder 5. The oil outlet of the second safety valve 20 is connected to the pipeline corresponding to the oil return port of the proportional valve 18. The oil inlet of the second check valve 21 is connected to the pipeline corresponding to the main oil outlet of the third hydraulic check valve 17. The second check valve 21 is connected in parallel to the pipeline corresponding to the rod chamber oil port of the open cylinder 5. The oil outlet of the second check valve 21 is connected to the pipeline corresponding to the oil return port of the proportional valve 18. The oil inlet of the second directional valve 19 is connected to the main oil inlet pipe. The oil return port of the second directional valve 19 is connected to the main oil return pipe. The working oil port of the second directional valve 19 is connected in parallel to the first hydraulic check valve 15, the second hydraulic check valve 16 and the third hydraulic check valve 17 through oil pipes. When the second directional valve 19 is energized, the first hydraulic check valve 15, the second hydraulic check valve 16, and the third hydraulic check valve 17 are opened, and the proportional valve 18 can drive the open cylinder 5 to move; when the second directional valve 19 is de-energized, the first hydraulic check valve 15, the second hydraulic check valve 16, and the third hydraulic check valve 17 are closed, and the position of the open cylinder 5 is locked.

[0029] The proportional valve 18 employs a closed-loop automatic control principle, enabling the open cylinder 5 to rapidly extend and retract while automatically decelerating as it approaches the target stroke to avoid hydraulic shock. The accumulator 8 absorbs the hydraulic shock generated during the operation of the open cylinder 5, stabilizing and balancing the pressure of the control system. The hydraulic proportional balance control circuit of this application operates as follows during the continuous rolling mill: During the rolling preparation stage, the system first performs pressure presetting. Pressure oil is introduced into the main oil inlet pipe. The Y1A control port of the first directional valve 14 in the balance control system is energized. After the pressure oil is reduced to the set pressure by the pressure reducing valve 10, it enters the oil inlet of the first directional valve 14 through the first check valve 12, and then flows into the rodless chamber of the closing cylinder 3 through the second working oil port of the first directional valve 14. The oil in the rod chamber of the closing cylinder 3 flows back to the main return oil pipe through the return oil port of the first directional valve 14. The closing cylinder 3 remains in the extended state, providing a stable core-holding force preparation for the mandrel roller 6 of the mandrel support frame 2. At this time, the accumulator 8 is pressurized to the set pressure through the parallel branch and is in a standby state to absorb the impact of subsequent actions. The second directional valve 19 in the proportional control system is in a de-energized state, and the first hydraulic check valve 15, the second hydraulic check valve 16 and the third hydraulic check valve 17 are all closed. The opening cylinder 5 remains in the initial contraction position, and the mandrel support frame 2 is in the closed preparation state.

[0030] During the rolling process, when the mandrel support frame 2 is open, the system activates the proportional control system according to the rolling signal. The second directional valve 19 is energized, and the pressure oil in the main oil inlet pipe enters the control chambers of the first hydraulic check valve 15, the second hydraulic check valve 16, and the third hydraulic check valve 17, pushing the valve core to open and opening the main oil circuit. At the same time, the proportional valve 18 receives the closed-loop control signal, its first working port opens and adjusts the output flow. The pressure oil flows into the rodless chamber of the open cylinder 5 through the second hydraulic check valve 16, and the oil in the rod chamber of the open cylinder 5 flows back to the main return oil pipe through the second working port of the third hydraulic check valve 17 and the proportional valve 18. The open cylinder 5 begins to extend to drive the mandrel support frame 2 to open. When the open cylinder 5 extends to near the target stroke, the proportional valve 18 automatically reduces the flow rate according to the feedback signal, and the open cylinder 5 decelerates to avoid impact with related structures. During this process, the pressure fluctuation generated by the rapid action of the open cylinder 5 is transmitted to the balance control system through the pipeline. The accumulator 8 absorbs the pressure peak through expansion and releases oil to maintain the pressure stability of the balance control system, ensuring that the closed cylinder 3 always maintains a stable extension state. The push head of both cylinders makes no gap contact with the moving crossbeam, and no mechanical impact is generated.

[0031] During the closing phase of the mandrel support frame 2, after receiving the signal indicating completion of pipe disconnection, the system switches the action logic. The proportional valve 18 receives the reverse control signal, its second working port opens and adjusts the flow rate. The pressurized oil flows into the rod chamber of the open cylinder 5 through the third hydraulic check valve 17. The oil in the rodless chamber of the open cylinder 5 flows back to the main return oil pipe through the first working port of the second hydraulic check valve 16 and the proportional valve 18, and the open cylinder 5 begins to retract. Since the Y1A of the first directional valve 14 in the balance control system is always energized, the rodless chamber of the closing cylinder 3 is continuously supplied with the set pressure oil. At the same time as the open cylinder 5 retracts, the closing cylinder 3 pushes the swing frame 4 to move, causing the mandrel support frame 2 to gradually close. Similarly, when the open cylinder 5 retracts and approaches the target position, the proportional valve 18 automatically decelerates, and the accumulator 8 absorbs the impact generated by the retraction action to ensure a smooth closing action. Finally, the mandrel support frame 2 closes stably to support the mandrel.

[0032] During the stand-changing operation, the system enters the reset state. Y1B of the first directional valve 14 in the balance control system is energized, and the pressure oil flows into the rod chamber of the closed cylinder 3 through the first working oil port of the first directional valve 14. The oil in the rodless chamber of the closed cylinder 3 flows back to the main return oil pipe through the return oil port of the first directional valve 14, and the closed cylinder 3 retracts. At the same time, the proportional valve 18 controls the open cylinder 5 to fully retract to the initial position. Subsequently, the second directional valve 19 is de-energized, and the first hydraulic control check valve 15, the second hydraulic control check valve 16, and the third hydraulic control check valve 17 are closed, locking the position of the open cylinder 5. At this time, the pushers of both the closed cylinder 3 and the open cylinder 5 are separated from the moving crossbeam, and the mandrel support stand 2 is in a replaceable state. The operator can perform the stand replacement operation. After the replacement is completed, the system re-enters the rolling preparation stage.

[0033] It should be noted that, unless otherwise expressly specified and limited, the term "connection" or its synonyms should be interpreted broadly in this document. For example, "connection" can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, expressions such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. At the same time, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In addition, the terms "front," "rear," "left," "right," "upper," and "lower" in this document refer to the placement states shown in the accompanying drawings.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A hydraulic proportional balance control circuit for a mandrel support frame in a continuous rolling mill, characterized in that, It includes a main oil inlet pipe, a main oil return pipe, a proportional control system and a balance control system. The balance control system and the proportional control system are connected in parallel between the main oil inlet pipe and the main oil return pipe. The balance control system is connected to the closing cylinder (3) and is used to control the action of the closing cylinder (3) to realize the core-holding action of the mandrel support frame (2). The proportional control system is connected to the opening cylinder (5) and is used to control the action of the opening cylinder (5) to realize the opening and closing action of the mandrel support frame (2). Through the coordinated action of the proportional control system and the balance control system, the stable action control of the mandrel support frame (2) is realized.

2. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 1, characterized in that, The balance control system includes an accumulator (8), a ball valve (9), a pressure reducing valve (10), a first safety valve (11), a first check valve (12), a throttle valve (13), and a first directional valve (14). The main oil inlet pipe is connected to the oil inlet of the first directional valve (14), the oil return port of the first directional valve (14) is connected to the main oil return pipe, the first working oil port of the first directional valve (14) is connected to the rod chamber of the closing cylinder (3), and the second working oil port of the first directional valve (14) is connected to the rodless chamber of the closing cylinder (3). The pressure reducing valve (10) and the first check valve (12) are connected in series between the main oil outlet pipe and the oil inlet of the first directional valve (14), and the oil outlet of the first check valve (12) is connected to the oil inlet of the first directional valve (14). The inlet of the accumulator (8) is connected to the main oil pipe branch of the first directional valve (14) and forms a parallel layout with the main oil pipe branch. The inlets of the accumulator (8), ball valve (9), and first safety valve (11) are all connected to the same main oil pipe branch of the first directional valve (14) and are arranged in parallel on the main oil pipe branch. The outlet of the ball valve (9) and the outlet of the first safety valve (11) are respectively connected to the main return oil pipe. The throttle valve (13) is connected in series in the pipeline between the working oil port of the first directional valve (14) and the closing cylinder (3).

3. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 1, characterized in that, The proportional control system includes a first hydraulic check valve (15), a second hydraulic check valve (16), a third hydraulic check valve (17), a proportional valve (18), a second directional valve (19), a second safety valve (20), and a second check valve (21). The inlet of the proportional valve (18) is connected to the main inlet pipe, and the return port of the proportional valve (18) is connected to the main return pipe; the first working port of the proportional valve (18) is connected to the main inlet pipe of the second hydraulic check valve (16), and the second working port of the proportional valve (18) is connected to the main inlet pipe of the third hydraulic check valve (17). The first hydraulic check valve (15) is connected in series between the main oil outlet pipe and the oil inlet of the proportional valve (18), and the main oil inlet of the first hydraulic check valve (15) is connected to the main oil inlet pipe. The main outlet of the second hydraulic check valve (16) is connected to the rodless chamber oil port pipeline of the open cylinder (5); The main oil outlet of the third hydraulic check valve (17) is connected to the rod chamber oil port pipeline of the open cylinder (5); The oil inlet of the second safety valve (20) is connected to the pipeline corresponding to the main oil outlet of the second hydraulic check valve (16), and the second safety valve (20) is connected in parallel to the pipeline corresponding to the rodless chamber oil port of the open cylinder (5), and the oil outlet of the second safety valve (20) is connected to the pipeline corresponding to the return oil port of the proportional valve (18). The oil inlet of the second check valve (21) is connected to the pipeline corresponding to the main oil outlet of the third hydraulic check valve (17), and the second check valve (21) is connected in parallel to the pipeline corresponding to the rod chamber oil port of the open cylinder (5), and the oil outlet of the second check valve (21) is connected to the pipeline corresponding to the return oil port of the proportional valve (18). The oil inlet of the second directional valve (19) is connected to the main oil inlet pipe, the oil return port of the second directional valve (19) is connected to the main oil return pipe, and the working oil port of the second directional valve (19) is connected in parallel with the first hydraulic control check valve (15), the second hydraulic control check valve (16) and the third hydraulic control check valve (17) through oil pipes respectively.

4. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 2, characterized in that, The first directional valve (14) has two control ports, Y1A and Y1B. When Y1A is energized, constant pressure oil is introduced into the rodless chamber of the closing cylinder (3), and the closing cylinder (3) remains in the extended state. When Y1B is energized, oil returns to the rodless chamber of the closing cylinder (3), and the closing cylinder (3) retracts.

5. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 3, characterized in that, When the second directional valve (19) is energized, the first hydraulic check valve (15), the second hydraulic check valve (16), and the third hydraulic check valve (17) are opened, and the proportional valve (18) can drive the open cylinder (5) to move; when the second directional valve (19) is de-energized, the first hydraulic check valve (15), the second hydraulic check valve (16), and the third hydraulic check valve (17) are closed, and the position of the open cylinder (5) is locked.

6. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 3, characterized in that, The proportional valve (18) adopts the closed-loop automatic control principle to realize the rapid extension and retraction of the open cylinder (5) while automatically decelerating when approaching the target stroke, thus avoiding hydraulic shock.

7. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 2, characterized in that, The accumulator (8) is used to absorb the hydraulic shock generated when the open cylinder (5) is activated, and to stabilize the pressure of the balance control system.

8. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 2, characterized in that, The output pressure of the pressure reducing valve (10) is adjustable and is used to set the core clamping force of the closing cylinder (3).

9. The hydraulic proportional balance control circuit for the mandrel support frame of a continuous rolling mill according to claim 2, characterized in that, The throttle valve (13) is used to adjust the extension and retraction speed of the closed cylinder (3).

Images