A hot rolling roll balance hydraulic control system and method

Abstract

A hot rolling roll balancing hydraulic control system and method belong to the control field. It includes a balancing device for the work roll and a balancing device for the backup roll; the balancing device for the work roll consists of four hydraulic cylinders for balance adjustment and bosses installed on the housing; two backup roll balance cylinders are arranged on the balance cylinder bosses of each work roll to form the balancing device for the backup roll; the balancing device for the backup roll and the balancing device for the work roll form an integrated structure. A pressure regulating circuit for the rod chamber is added to the upper backup roll balance hydraulic circuit. Combining the control of the pressure difference between the oil in the rodless chamber and the rod chamber, and adopting the "low pressure" control of the rod chamber, it avoids impurities at the work site from entering the rod chamber, increases the overbalance coefficient of the backup roll, improves the control accuracy of the roll, reduces the impact and vibration of the rolling mill, improves the stability of the roll system of the rolling mill, and increases the service life of the oil film bearing. It can be widely used in the operation, maintenance and transformation fields of the hydraulic system of the upper backup roll of hot rolling mills.

Description

Technical Field

[0001] The present invention belongs to the field of automatic control, and particularly relates to a device and method for improving the lifting stability of a backup roll hydraulic cylinder and preventing oil leakage on a hot rolling mill. Background Art

[0002] The R2 roughing mill is a core equipment on the hot strip rolling production line, generally a four-high reversible rolling mill. Its roll balance hydraulic system (also known as the roll balance device) is an important part of the R2 roughing mill. Its main function is to balance the weights of components such as rolls, safety sockets, and lead screws, eliminate the gaps in the vertical chain direction of the rolling mill, and ensure the roll gap accuracy.

[0003] The roll balance hydraulic system of the hot rolling R2 roughing mill consists of a balance device for the work roll (abbreviated as work roll balance) and a balance device for the backup roll (abbreviated as backup roll balance). Among them, the balance device for the work roll is generally composed of 4 balance cylinder bosses installed on the housing. The balance device for the backup roll usually has two structural forms. One is composed of 1 balance cylinder installed on the top of the rolling mill and a lifting crossbeam; the other is designed as an integral body with the work roll balance device, that is, 2 backup roll balance cylinders are designed on each work roll balance cylinder boss. All these balance cylinders are powered by the roll balance system to achieve the balance action of the rolls.

[0004] A certain hot rolling R2 roughing mill of Baosteel was designed by a foreign company. During years of use, it was found that the state of its roll balance system was not very stable, and there were often failures of oil leakage due to damage to the cylinder head seals of the balance cylinders. The average service life was about 3 months, and the oil leakage failure occurred 2 times a month on average, 24 times a year, which had a greater impact on production. Moreover, the impact on the upper roll system was large and unstable, and the oil film bearings of the upper backup rolls were also damaged many times. Although after many analyses and measures such as increasing the lubricating oil amount of the oil film bearings and improving the manufacturing process of the oil film bearing bushings, the state of the oil film bearings has improved, the problem still exists, which poses a great threat to equipment maintenance and normal production.

[0005] In the Chinese invention patent application with the publication date of November 6, 2018 and the publication number of CN 108757595A, a "hydraulic cylinder pressure compensation buffer control circuit" is disclosed, which includes a constant pressure variable pump, an accumulator, a pressure compensator, a proportional valve, a shuttle valve, and a hydraulic cylinder. By the combined use of the pressure compensator and the shuttle valve, the proportional valve can perform proportional speed control on both directions of the hydraulic cylinder, enabling the pressure difference before and after the proportional valve to remain constant, so that the speed of the actuator is not affected by the load change, and avoiding the formation of a very high peak pressure instantaneously in the system due to the action of the flowing medium or the inertia of the actuator in the system, resulting in hydraulic shock. Since the pressure compensator detects the pressure from the load, the output flow of the system has a strong anti-load interference ability and is applicable to occasions with large load changes and high requirements for speed stability.

[0006] In a Chinese invention patent with an authorization announcement date of June 23, 2020 and an authorization announcement number of CN 109026860 B, a "proportional servo valve-controlled hydraulic support platform column cylinder system and pressure control method" is disclosed. An asynchronous motor is connected to a fixed-displacement pump; a filter, the fixed-displacement pump, and a proportional servo valve are connected in sequence; the proportional servo valve is connected to a hydraulic lock and a column cylinder in sequence; the input end of the fixed-displacement pump is separately connected to a fuel tank through the filter, and the output end of the fixed-displacement pump is connected to a port of the proportional servo valve; a proportional relief valve is connected between port 2 and port 4 of the proportional servo valve; under the action of the fixed-displacement pump, hydraulic oil outputs high-pressure oil with a certain flow rate through the filter to control the column cylinder; the flow rate of the hydraulic oil is changed by adjusting the proportional servo valve to control the pressure of the column cylinder; finally, the low-pressure oil at the oil outlet of the column cylinder returns to the fuel tank through the diversion of the proportional servo valve. This solution essentially improves the stroke accuracy of the hydraulic cylinder by controlling the size of the hydraulic flow rate.

[0007] Obviously, the existing conventional pressure control method is that the rodless cavity has high pressure and the rod chamber has zero-pressure oil return, and the disadvantage is that it is easy for dust and water vapor to enter the rod chamber. Another method is to achieve balanced force control according to the difference in acting areas through equal-pressure control of the rod chamber and the rodless cavity. The disadvantage is that the rod chamber is always in a high-pressure state, which is prone to oil leakage and wear. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a hot rolling roll balancing hydraulic control system and method. It balances the weight of the backup roll through the pressure changes in the two oil cavities (i.e., the rodless cavity and the rod chamber) of the hydraulic cylinder, combines the pressure difference control between the rodless cavity and the rod chamber, and adopts low-pressure control of the rod chamber to improve the service life of the cylinder head seal of the hydraulic cylinder; at the same time, the overbalance coefficient of the backup roll is increased, and by adjusting the pressure of the hydraulic oil in the rodless cavity and the rod chamber, the roll control accuracy is improved and the vibration of the rolling mill is reduced.

[0009] The technical solution of the present invention is: to provide a hot rolling roll balancing hydraulic control system, including an upper backup roll balancing device, characterized in that:

[0010] The upper backup roll balancing device is composed of a backup roll balancing device and a work roll balancing device;

[0011] Below the upper backup roll bearing seat fixed to the screwdown device, with the rotation axis of the upper backup roll as the center line, two groups of backup roll balancing hydraulic cylinders are symmetrically arranged to form the backup roll balancing device;

[0012] On the upper work roll bearing seat located below the upper backup roll bearing seat, with the rotation axis of the upper work roll as the center line, two groups of upper bosses are symmetrically arranged, and below each upper boss, a work roll balancing hydraulic cylinder is correspondingly arranged to form the work roll balancing device;

[0013] A balance cylinder boss is provided between each work roll balance hydraulic cylinder and the corresponding backup roll balance hydraulic cylinder;

[0014] The work roll balance hydraulic cylinder and the backup roll balance hydraulic cylinder are fixed as a whole through the balance cylinder boss;

[0015] The work roll balance hydraulic cylinder and the backup roll balance hydraulic cylinder are powered by the upper backup roll balance hydraulic circuit to achieve the balance action of the roll and eliminate the clearance in the vertical chain direction of the rolling mill;

[0016] The roll balance hydraulic system controls the total balance force of the oil cylinders in the upper backup roll roll system in combination with the equipment weight involved in the upper backup roll roll system;

[0017] In the roll balance hydraulic system, a rod chamber pressure regulating circuit is provided between the rod chamber of each hydraulic cylinder and the oil inlet; a rodless chamber pressure regulator circuit is provided between the rodless chamber of each hydraulic cylinder and the oil return port; a throttle speed regulating circuit is provided between the rodless chamber of each hydraulic cylinder and the oil inlet;

[0018] In the roll balance hydraulic system, by setting a rodless chamber pressure regulating circuit, a rod chamber pressure regulating circuit and a throttle speed regulating circuit in the upper backup roll balance hydraulic circuit, the rodless chamber is in a "high pressure" state and the rod chamber is in a "low pressure" state under the balanced state; thus, the balance function, the lifting function of the upper backup roll when replacing the work roll and the rapid descent function of the upper backup roll are realized.

[0019] Specifically, the upper backup roll balance device includes a work roll balance device and a backup roll balance device; the work roll balance device consists of four hydraulic cylinders for balance adjustment and bosses installed on the housing; two backup roll balance cylinders are arranged on the balance cylinder boss of each work roll to form the backup roll balance device; the backup roll balance device and the work roll balance device form an integral structure;

[0020] In the roll balance hydraulic system, a first solenoid valve DCF1 is provided between the oil inlet and the rodless chamber of the hydraulic cylinder; a second solenoid valve DCF2 and a rod chamber pressure regulating circuit are provided between the oil inlet and the rod chamber of the hydraulic cylinder; a third solenoid valve DCF3 and a throttle speed regulating circuit are provided between the rodless chamber and the oil inlet.

[0021] Furthermore, the rodless chamber pressure regulating circuit includes a second overflow valve YLF2 or a third overflow valve YLF3 provided between the rodless chamber of the hydraulic cylinder and the oil return port, and the hydraulic oil pressure in the rodless chamber of the hydraulic cylinder is controlled through the provided second overflow valve YLF2 or third overflow valve YLF3.

[0022] Further, the pressure regulating circuit of the rod chamber includes a first overflow valve YLF1 and a pressure reducing valve JYF3 arranged between the rod chamber of the hydraulic cylinder and the oil inlet. The pressure of the rod chamber of the hydraulic cylinder is regulated by the first overflow valve YLF1 and the pressure reducing valve JYF3, and the pressure P is set by the pressure reducing valve JYF3 and the first overflow valve YLF1.

[0023] Further, the throttle speed control circuit includes a bidirectional throttle valve arranged between the rodless chamber of the hydraulic cylinder and the oil inlet. Through the bidirectional throttle valve, the lifting or lowering speed of the upper backup roll is controlled.

[0024] The technical solution of the present invention also provides a control method for the above-mentioned hot rolling roll balance hydraulic control system, which is characterized in that:

[0025] 1) Calculate the total balance weight of the upper backup roll system:

[0026] 2) Calculate the hydraulic balance force of the upper backup roll:

[0027] 3) Adopt overbalance force protection control for the roll to control the total balance force of the oil cylinders in the upper backup roll system;

[0028] 4) Through the control of the roll balance hydraulic system, realize the balance function between the rodless chamber and the rod chamber, realize the lifting function of the upper backup roll, and realize the rapid lowering function of the upper backup roll.

[0029] Specifically, the total balance weight of the upper backup roll system includes the sum of the weight of the backup roll, the weight of the WS bearing block, the weight of the DS bearing block, the weight of all liners of the bearing block, the weight of two oil film bearings and two thrust bearings, and the weight of the locking and end covers.

[0030] Specifically, the hydraulic balance force of the upper backup roll is:

[0031] F 总 = k × G 总

[0032] Where:

[0033] K is the overbalance coefficient of the backup roll system; F 总 is the total balance force of the oil cylinder; G 总 is the total weight of the backup roll; the value range of k is 1.1 - 1.35.

[0034] Specifically, the total balance force of the oil cylinders in the upper backup roll system is calculated according to the following formula:

[0035]

[0036] Where: D is the diameter of the cylinder barrel of the hydraulic cylinder, d is the diameter of the piston rod of the hydraulic cylinder, p1 is the pressure in the rodless cavity of the hydraulic cylinder, p2 is the pressure in the rod cavity of the hydraulic cylinder, and n is the number of hydraulic cylinders.

[0037] Further, the balance function between the rodless cavity and the rod cavity is realized through the following control process of the balance hydraulic circuit of the upper backup roll:

[0038] The pressure in the rodless cavity of the hydraulic cylinder is regulated by the first overflow valve YLF1 or the second overflow valve YLF2 in the rodless cavity pressure regulating circuit. The pressure in the rod cavity of the hydraulic cylinder is regulated by the first overflow valve YLF1 and the pressure reducing valve JYF3 in the rod cavity pressure regulating circuit to ensure the pressure difference between the two cavities of the hydraulic cylinder, so as to improve the balance force and realize the balance function of the upper backup roll system. At the same time, after the hydraulic oil is decompressed by the pressure reducing valve JYF3 and kept pressurized by the first overflow valve YLF1 through the oil inlet, it enters the rod cavity of the hydraulic cylinder through the second solenoid valve DCF2. And the hydraulic oil in the rodless cavity enters the rodless cavity through the oil inlet to the first solenoid valve DCF1 and is regulated by the two overflow valves in the rodless cavity pressure regulating circuit, thus realizing the "high pressure" state in the rodless cavity and the "low pressure" state in the rod cavity under the balanced state.

[0039] Further, the realization of the lifting function of the upper backup roll is achieved through the following control process of the balance hydraulic circuit of the upper backup roll:

[0040] Energize the solenoid valve A coil of the second solenoid valve DCF2, energize the solenoid valve B coil of the first solenoid valve DCF1, and energize the solenoid valve A coil of the third solenoid valve DCF3. The pressure in the rodless cavity of the hydraulic cylinder is regulated to high pressure by the overflow valve in the rodless cavity pressure regulating circuit, and at the same time, the rising speed of the backup roll is controlled by restricting the flow rate of the hydraulic oil through the throttle speed control circuit. The pressure in the rod cavity is regulated to a low pressure state by the overflow valve YLF1 and the pressure reducing valve JYF3 in the rod cavity pressure regulating circuit. When the pressing device rises rapidly, the backup roll is lifted together to realize the lifting function of the upper backup roll. At the same time, after the hydraulic oil is decompressed by the pressure reducing valve JYF3 and kept pressurized by the overflow valve YLF1 through the oil inlet, it enters the rod cavity of the hydraulic cylinder through the second solenoid valve DCF2. The hydraulic oil in the rodless cavity enters the rodless cavity through the oil inlet to the third solenoid valve DCF3, passes through the throttle speed control circuit, and then is regulated by the two overflow valves in the rodless cavity pressure regulating circuit. The upper backup roll rises according to the speed adjusted by the throttle speed control circuit to avoid excessive impact on the rolling mill due to too fast rising speed.

[0041] Further, the realization of the rapid descent function of the upper backup roll is achieved through the following control process of the balance hydraulic circuit of the upper backup roll:

[0042] Energize the solenoid valve B terminal of the second solenoid valve DCF2, the solenoid valve B terminal of the first solenoid valve DCF1, and the solenoid valve B of the third solenoid valve DCF3. At this time, the oil return pressure of the rodless chamber of the hydraulic cylinder is 0. The flow rate of the hydraulic oil is restricted through the throttle speed control circuit to control the descending speed of the backup roll. At this time, the rod chamber of the hydraulic cylinder directly receives oil from the oil inlet and is in a high-pressure state, thereby realizing the rapid descending function of the upper backup roll. At the same time, the hydraulic oil directly enters the rod chamber of the hydraulic cylinder through the second solenoid valve DCF2, and the hydraulic oil in the rodless chamber of the hydraulic cylinder returns to the oil return port through the third solenoid valve DCF3 via the throttle speed control circuit. The descending speed is adjusted through the throttle speed control circuit to prevent damage to the backup roll caused by too fast a descending speed.

[0043] Compared with the prior art, the advantages of the present invention are:

[0044] 1. In the technical solution of the present invention, a rod chamber pressure regulating circuit is added at the oil inlet. After the solenoid valve A terminal coil of the second solenoid valve DCF2 is energized, the hydraulic oil is decompressed by the pressure reducing valve JYF3, and the pressure is maintained by the overflow valve YLF1 and then enters the rod chamber of the hydraulic cylinder. So that in addition to being in a "high-pressure" state during the rapid descending function, the rod chamber has been in a "low-pressure" control state (the rapid descending function can only be used during the backup roll replacement once a month). The "low-pressure" control state is beneficial to increasing the service life of the cylinder head seal, and at the same time, it also prevents impurities (including water and scale) at the work site from entering the rod chamber.

[0045] 2. In the technical solution of the present invention, by adjusting the pressures of the hydraulic oil in the rod chamber and the rodless chamber to meet the requirement that the roll overbalance coefficient is controlled within a certain range, the upper backup roll is in an optimal balance state, reducing the impact vibration of the rolling mill, improving the stability of the roll system of the rolling mill, and increasing the service life of the oil film bearing (if the roll overbalance coefficient is too small, it will cause insufficient balance force, and it needs to rely on the balance force of the work roll balance cylinder to meet the requirements of normal operation. However, since the roughing rolling mill is a reversible rolling mill with large and frequent changes in the roll gap, it is very likely to cause poor contact of the upper roll system components, resulting in a large impact during biting, thus leading to an unstable balance state of the upper roll system and easily damaging the components of the upper roll system).

[0046] 3. In the control method, by combining the control of the pressure difference between the hydraulic oil in the rodless chamber and the rod chamber, and adopting the "low-pressure" control of the rod chamber to improve the service life of the cylinder head seal of the hydraulic cylinder.

[0047] 4. In the control method, the overbalance coefficient of the backup roll is increased, improving the roll control accuracy and reducing the vibration of the rolling mill. Description of the Drawings

[0048] Figure 1 It is a simple schematic diagram of the rolling mill structure;

[0049] Figure 2 This is a schematic diagram of the hydraulic control circuit for the backup roll balance system of the present invention.

[0050] In the figure, 1 is the screw down device, 2 is the upper backup roll bearing block, 3 is the backup roll balance hydraulic cylinder, 4 is the work roll balance hydraulic cylinder, 5 is the balance cylinder boss, 6 is the upper work roll bearing block, and 7 is the upper boss. Detailed implementation manners

[0051] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0052] Figure 1 In this, the roll balance hydraulic system described in the present technical solution is composed of a balance device for work rolls (abbreviated as work roll balance) and a balance device for backup rolls (abbreviated as backup roll balance).

[0053] Among them, the balance device for work rolls is composed of 4 hydraulic cylinder bosses for balance adjustment (abbreviated as hydraulic cylinders, balance cylinders or oil cylinders) installed on the housing (when the backup rolls and work rolls are removed inside the rolling mill and the upper cover is lifted, it is actually an empty frame. In this empty frame, the backup rolls and work rolls need to be installed. This empty frame is two frame-like structures like door frames, and the industry customarily calls it a "housing"). The balance device for backup rolls is designed integrally with the work roll balance device, that is, two backup roll balance cylinders are designed on each balance cylinder boss of the work roll. All these balance cylinders are provided with power sources by the roll balance hydraulic system (also known as the balance hydraulic circuit, abbreviated as the hydraulic circuit) to realize the balance action of the rolls, eliminate the gap in the vertical chain direction of the rolling mill, and ensure the roll gap accuracy.

[0054] Specifically, as shown in Figure 1 , below the upper backup roll bearing block 2 fixedly connected to the screw down device 1, two groups of backup roll balance hydraulic cylinders 3 are symmetrically arranged with the rotation axis of the upper backup roll as the center line.

[0055] On the upper work roll bearing block 6 located below the upper backup roll bearing block, two groups of upper bosses 7 are symmetrically arranged with the rotation axis of the upper work roll as the center line. Below each upper boss, a work roll balance hydraulic cylinder is correspondingly arranged.

[0056] Between each work roll balance hydraulic cylinder and the corresponding backup roll balance hydraulic cylinder, a balance cylinder boss is arranged.

[0057] The work roll balance hydraulic cylinders and the backup roll balance hydraulic cylinders are fixed and connected into one body through the balance cylinder bosses.

[0058] All the work roll balance hydraulic cylinders and backup roll balance hydraulic cylinders constitute the total balance cylinders of the upper backup roll system (hereinafter abbreviated as balance cylinders or hydraulic cylinders).

[0059] The working roll balance hydraulic cylinder and the backup roll balance hydraulic cylinder are both powered by the roll balance hydraulic system.

[0060] The oil chambers of the balance cylinders are divided into rod chambers and rodless chambers. The rod chambers and rodless chambers of each balance cylinder are respectively connected to the oil inlet and oil return ports of the hydraulic oil supply system through corresponding pipelines.

[0061] During actual operation, if oil is supplied to the rod chamber of the balance cylinder, the piston of the balance cylinder retracts, and the push rod connected to the piston retracts. At this time, the rodless chamber of the balance cylinder is in a state of hydraulic oil reflux. If oil is supplied to the rodless chamber of the balance cylinder, the piston of the balance cylinder moves forward, and the push rod connected to the piston extends. At this time, the rod chamber of the balance cylinder is in a state of hydraulic oil reflux; thereby realizing the balance control function of the balance cylinder.

[0062] The specific implementation solution of the pressure control of the roll balance hydraulic system in the technical solution of the present invention is as follows:

[0063] Step 1: Control in combination with the total balance weight of the upper backup roll system:

[0064] This technical solution controls in combination with the weights of the equipment involved in the upper backup roll system, specifically as follows: including the weight G1 of the backup roll, the weight G2 of the WS bearing housing, the weight G3 of the DS bearing housing, the total weight of all liners of the bearing housing is about G4, the weight of 2 oil film bearings and 2 thrust bearings is about G5, the weight of the locking and end covers, etc. is about G6... and the sum of all components.

[0065] Then the weight of the upper backup roll assembly is approximately:

[0066] G 总 = G1 + G2 + G3 + G4 + G5 + G6 +....

[0067] Step 2: Control the hydraulic balance force of the upper backup roll:

[0068] Control the total balance force of the hydraulic cylinders in the upper backup roll system, that is, the total balance force of the hydraulic cylinders in the upper backup roll system that needs to be balanced is:

[0069] F 总 = k × G 总

[0070] Where:

[0071] k ---- The overbalance coefficient of the backup roll system (value range 1.1 - 1.35)

[0072] F 总 ---- The total balance force of the hydraulic cylinders

[0073] G 总 ---- The total weight of the backup rolls

[0074] To keep an upward acting force on the backup roll all the time, the components between the backup roll bearing and the screw down device are tightly connected to eliminate the gaps. In this technical solution, combined with the on-site cylinder balance, the over-balance force protection control of the roll is adopted to meet the balance requirements of the upper backup roll system.

[0075] Step 3: Hydraulic cylinder balance force pressure control:

[0076]

[0077] Where:

[0078] D ---- Cylinder barrel diameter of the hydraulic cylinder

[0079] d ---- Piston rod diameter of the hydraulic cylinder

[0080] p1 ---- Pressure in the rodless cavity of the hydraulic cylinder

[0081] p2 ---- Pressure in the rod cavity of the hydraulic cylinder

[0082] n ----- Number of hydraulic cylinders

[0083] This technical solution combines the pressure p2 in the rodless cavity of the hydraulic balance system and is determined according to the power source pressure provided by the roll balance system. When the pressure p1 in the rod cavity selects the low-pressure range (0.5 - 5.5 Mpa), it can meet the requirements of the hydraulic cylinder balance force at the same time. In this way, it can not only greatly extend the service life of the cylinder head seal, but also ensure that there is always a certain positive pressure in the rod cavity, prevent water and iron oxide powder from entering the hydraulic cylinder and polluting the oil, and can also improve the balance force of the upper roll system, improve the contact state of the upper roll system, reduce the impact vibration, and greatly improve the rolling stability, thereby indirectly improving the service life of the oil film bearing.

[0084] In this technical solution, by keeping the rod cavity in a "pressurized" control state all the time (strictly speaking, it should be a "positive pressure" control state, that is, ensuring that the hydraulic oil in the rod cavity is always in a "positive pressure" state relative to the working environment), foreign objects from the outside are prevented from entering.

[0085] Step 4: Hydraulic circuit control of the R2 roll balance system:

[0086] As Figure 2 shown, the rod cavities (or rodless cavities) of every two hydraulic cylinders in the figure are respectively connected in parallel as one path. Between the rod cavity of each hydraulic cylinder and the oil inlet, a rod cavity pressure regulating circuit is set; between the rodless cavity of each hydraulic cylinder and the oil return port, a rodless cavity pressure regulating circuit is set, and between the rodless cavity of each hydraulic cylinder and the oil inlet, a throttle speed regulating circuit is set.

[0087] Specifically, a first solenoid valve DCF1 is provided between the oil inlet and the rodless cavity of the hydraulic cylinder; a second solenoid valve DCF2 and a rod cavity pressure regulating circuit are provided between the oil inlet and the rod cavity of the hydraulic cylinder; a third solenoid valve DCF3 and a throttle speed regulating circuit are also provided between the rodless cavity and the oil inlet.

[0088] Among them, the rod cavity pressure regulating circuit includes a first overflow valve YLF1 and a pressure reducing valve JYF3 provided between the rod cavity of the hydraulic cylinder and the oil inlet.

[0089] The rodless cavity pressure regulating circuit includes a second overflow valve YLF2 or a third overflow valve YLF3 provided between the rodless cavity of the hydraulic cylinder and the oil return port.

[0090] The throttle speed regulating circuit includes a bidirectional throttle valve provided between the rodless cavity of the hydraulic cylinder and the oil inlet.

[0091] Combined with the balance hydraulic circuit of the upper backup roll of the rolling mill, the following functional controls are adopted in this technical solution:

[0092] 1) Balance function: The solenoid valve A end coils of the first solenoid valve DCF1 and the second solenoid valve DCF2 are energized, and the third solenoid valve DCF3 is not energized and is in the middle position. At this time, the pressure in the rodless cavity of the balance cylinder is regulated by the first overflow valve YLF1 or the second overflow valve YLF2 of the rodless cavity pressure regulating circuit according to the p1 value calculated in step three, and the pressure in the rod cavity is regulated by the first overflow valve YLF1 and the pressure reducing valve JYF3 in the rod cavity pressure regulating circuit according to the p1 value calculated in step three. The pressure P is set by the pressure reducing valve JYF3 and the first overflow valve YLF1, and the range is P ≤ the pressure p1 in the rod cavity. In this way, the pressure difference between the two cavities of the oil cylinder is large, which can greatly improve the balance force and realize the balance function of the upper backup roll system. Apply an upward force to the backup roll to make all components of the upper backup roll fit tightly.

[0093] The hydraulic oil is decompressed by the pressure reducing valve JYF3 and kept under pressure by the first overflow valve YLF1 through the oil inlet, then enters the rod cavity of the hydraulic cylinder through the second solenoid valve DCF2. At the same time, the hydraulic oil in the rodless cavity passes through the oil inlet to the first solenoid valve DCF1, and after being regulated by the two overflow valves of the rodless cavity pressure regulating circuit, it enters the rodless cavity. In the balanced state, the rodless cavity is in a "high pressure" state and the rod cavity is in a "low pressure" state. It does not pass through the throttle speed regulating circuit, with a fast response speed. The backup roll bearing always fits the screw down device, and the adjustment response speed is fast.

[0094] In this technical solution, the throttle speed regulating circuit includes a set of bidirectional throttle valves provided between the rodless cavity and the oil inlet ( Figure 2Taking the example of setting a set of two-way throttle valves between the rodless chambers of every two hydraulic cylinders and the oil inlet port, since the two-way throttle valve can achieve different pressure or flow control in the forward and reverse flow directions of the hydraulic oil, setting a two-way throttle valve between the rodless chamber of the hydraulic cylinder and the oil inlet port can limit the flow rate or flow of different hydraulic oils respectively during the oil supply or oil return process of the oil cylinder without a rod, and further achieve different control effects on the pressure of the hydraulic oil in the rodless chamber.

[0095] As Figure 2 As shown in [reference], the described two-way throttle valve is formed by connecting two one-way throttle valves in series in a "back-to-back" manner. In the forward and reverse flow directions of the hydraulic oil, there is a throttle valve that can play a role in throttling and pressure regulation.

[0096] Connecting two one-way throttle valves in reverse series to form a two-way throttle valve group helps to reduce the number of spare parts and the operation and maintenance costs.

[0097] 2) Lifting function of the upper backup roll when replacing the work roll: Energize the solenoid valve A coil of the second solenoid valve DCF2, energize the solenoid valve B coil of the first solenoid valve DCF1, and energize the solenoid valve A coil of the third solenoid valve DCF3. At this time, the pressure in the rodless chamber of the balance cylinder is regulated to a high pressure by the overflow valve in the rodless chamber pressure regulating circuit, and at the same time, the flow rate of the hydraulic oil is restricted through the throttle speed regulating circuit to control the rising speed of the backup roll. The pressure in the rod chamber is regulated to a low pressure state by the overflow valve YLF1 and the pressure reducing valve JYF3 in the rod chamber pressure regulating circuit. The pressure is set by the pressure reducing valve JYF3 and the overflow valve YLF1, and the range is P ≤ the pressure p1 in the rod chamber. When the pressing device 1 (see Figure 1 as shown in [reference]) rises rapidly, the backup roll loses the downward pressure of the pressing device and rises together, realizing the lifting function of the upper backup roll. The lifting speed is adjusted by the throttle speed regulating circuit.

[0098] The hydraulic oil passes through the oil inlet port, is decompressed by the pressure reducing valve JYF3, and is kept pressurized by the overflow valve YLF1, then enters the rod chamber of the hydraulic cylinder through the second solenoid valve DCF2. At the same time, the hydraulic oil in the rodless chamber passes through the oil inlet port to the third solenoid valve DCF3, passes through the throttle speed regulating circuit, and then enters the rodless chamber after being regulated by the two overflow valves in the rodless chamber pressure regulating circuit. When the pressing device quickly lifts, the backup roll rises according to the adjusted speed of the throttle speed regulating circuit, avoiding excessive impact on the rolling mill due to too fast rising speed.

[0099] 3) Lowering function: Energize the solenoid valve B terminal of the second solenoid valve DCF2, the solenoid valve B terminal of the first solenoid valve DCF1, and the solenoid valve B of the third solenoid valve DCF3. At this time, the oil return pressure of the rodless chamber of the balance cylinder is 0. At the same time, the flow rate of the hydraulic oil is restricted through the throttle speed control circuit to control the lowering speed of the backup roll. At this time, the rod chamber of the balance cylinder directly receives oil from the oil inlet and is in a high-pressure state, realizing the fast lowering function of the upper backup roll. The lowering speed is adjusted by the throttle speed control circuit.

[0100] The hydraulic oil directly enters the rod chamber of the balance cylinder through the second solenoid valve DCF2. At the same time, the hydraulic oil in the rodless chamber of the balance cylinder passes through the throttle speed control circuit and returns to the oil return port through the third solenoid valve DCF3, realizing fast lowering. The lowering speed is adjusted by the throttle speed control circuit to prevent damage to the backup roll caused by too fast a lowering speed.

[0101] Embodiment

[0102] Taking the R2 upper backup roll balance device of Baosteel 1880 Hot Rolling Mill as an example, the main function of the upper backup roll balance device is to balance the weights of components such as the upper backup roll, safety socket, and lead screw, eliminate the clearance in the vertical chain direction of the rolling mill, and ensure the roll gap accuracy. Its upper backup roll balance device consists of 8 balance cylinders, which are installed in 4 balance cylinder bosses on the housing. There are 2 backup roll balance cylinders designed on each balance cylinder boss. These balance cylinders are powered by the roll balance system to realize the balance function of the upper roll system.

[0103] 1) Calculation of the total weight of the upper backup roll roll system balance:

[0104] ① Weight of the upper backup roll: The weight of the 1880R2 backup roll is 46.5 tons, the weight of the WS bearing housing is 11.6 tons, the weight of the DS bearing housing is 11.5 tons, the total weight of all liners of the bearing housing is about 0.5 tons, the weight of 2 oil film bearings and 2 thrust bearings is about 7.5 tons, and the weight of locking and end covers, etc. is about 6 tons.

[0105] Then the weight of the upper backup roll assembly is approximately:

[0106] G1 = 46.5 + 11.6 + 11.5 + 0.5 + 7.5 + 6 = 83.6 (tons)

[0107] ② The weight of 2 screw-down lead screws and 2 safety sockets is about: G2 = 12.2 (tons)

[0108] Then the total weight of the upper backup roll roll system balance is:

[0109] G = G1 + G2 = 95.8 (tons).

[0110] 2) Calculation of the hydraulic balance force of the upper backup roll:

[0111] There are 8 balance cylinders in the upper backup roll balance device of R2. The cylinder specification is Ф100 / Ф80×670. When the upper backup roll is in the balanced state, the pressure in the rodless cavity is 20.6 MPa, and the pressure in the rod cavity is 1.47 MPa.

[0112] Then the total balance force of the cylinders is:

[0113]

[0114] Among them:

[0115] D ---- The diameter of the cylinder barrel of the cylinder;

[0116] d ---- The diameter of the piston rod of the cylinder;

[0117] p1 ---- The pressure in the rodless cavity of the cylinder;

[0118] p2 ---- The pressure in the rod cavity of the cylinder;

[0119] n ---- The number of cylinders.

[0120] Then the overbalance coefficient k of the upper backup roll system is k = F / G = 128.7 / 95.8 = 1.343. According to past design and maintenance experience, the overbalance force coefficient of the roll is generally taken as about 1.3, so that the balance requirements of the upper backup roll system can be met.

[0121] In the technical solution of the present invention, a rod cavity pressure regulating circuit is added to the upper backup roll balance hydraulic circuit. Combining the control of the pressure difference between the hydraulic oils in the rodless cavity and the rod cavity, and adopting the "low pressure" control of the rod cavity, it avoids impurities at the work site from entering the rod cavity, which helps to improve the service life of the cylinder head seal of the hydraulic cylinder; by adjusting the pressures of the hydraulic oils in the rod cavity and the rodless cavity, it increases the overbalance coefficient of the backup roll, makes the upper backup roll in the optimal balance state, improves the roll control accuracy, reduces the impact and vibration of the rolling mill, improves the stability of the roll system of the rolling mill, and increases the service life of the oil film bearing.

[0122] The present invention can be widely used in the operation, maintenance and transformation fields of the upper backup roll hydraulic system of hot rolling mills.

Claims

1. A hot rolling roll balance hydraulic control system, including an upper backup roll balance device, characterized in that: The upper backup roll balance device is composed of a backup roll balance device and a work roll balance device; Below the upper backup roll bearing housing fixedly connected to the screw down device, with the rotation axis of the upper backup roll as the center line, two groups of backup roll balance hydraulic cylinders are symmetrically arranged to form the backup roll balance device; On the upper work roll bearing housing located below the upper backup roll bearing housing, with the rotation axis of the upper work roll as the center line, two groups of upper bosses are symmetrically arranged, and below each upper boss, a work roll balance hydraulic cylinder is correspondingly arranged to form the work roll balance device; Between each work roll balance hydraulic cylinder and the corresponding backup roll balance hydraulic cylinder, a balance cylinder boss is provided; The work roll balance hydraulic cylinder and the backup roll balance hydraulic cylinder are fixed together through the balance cylinder boss; The work roll balance hydraulic cylinder and the backup roll balance hydraulic cylinder are provided with a power source by the upper backup roll balance hydraulic circuit to realize the balance action of the roll and eliminate the clearance in the vertical chain direction of the rolling mill; The roll balance hydraulic system controls the total balance force of the oil cylinders in the upper backup roll roll system in combination with the equipment weight involved in the upper backup roll roll system; In the roll balance hydraulic system, between the rod chamber of each hydraulic cylinder and the oil inlet, a rod chamber pressure regulating circuit is provided; between the rodless chamber of each hydraulic cylinder and the oil return port, a rodless chamber pressure regulating circuit is provided, and between the rodless chamber of each hydraulic cylinder and the oil inlet, a throttle speed regulating circuit is provided; In the roll balance hydraulic system, by setting a rodless chamber pressure regulating circuit, a rod chamber pressure regulating circuit and a throttle speed regulating circuit in the upper backup roll balance hydraulic circuit, the rodless chamber is in a "high pressure" state and the rod chamber is in a "low pressure" state under the balanced state; thus realizing the balance function, the lifting function of the upper backup roll when replacing the work roll and the rapid lowering function of the upper backup roll.

2. The hot rolling roll balance hydraulic control system according to claim 1, characterized in that The upper backup roll balance device includes a work roll balance device and a backup roll balance device; The work roll balance device is composed of four hydraulic cylinders for balance adjustment and bosses installed on the housing; Two backup roll balance cylinders are arranged on the balance cylinder boss of each work roll to form the backup roll balance device; The backup roll balance device and the work roll balance device form an integral structure; In the roll balance hydraulic system, a first solenoid valve DCF1 is provided between the oil inlet and the rodless chamber of the hydraulic cylinder; a second solenoid valve DCF2 and a rod chamber pressure regulating circuit are provided between the oil inlet and the rod chamber of the hydraulic cylinder; a third solenoid valve DCF3 and a throttle speed regulating circuit are provided between the rodless chamber and the oil inlet.

3. The hot rolling roll balance hydraulic control system according to claim 1, characterized in that The rodless chamber pressure regulating circuit includes a second relief valve YLF2 or a third relief valve YLF3 provided between the rodless chamber of the hydraulic cylinder and the oil return port, and the hydraulic oil pressure in the rodless chamber of the hydraulic cylinder is controlled through the provided second relief valve YLF2 or third relief valve YLF3.

4. The hot rolling roll balance hydraulic control system according to claim 1, characterized in that The described rod-end pressure regulating circuit includes a first overflow valve YLF1 and a pressure reducing valve JYF3 arranged between the rod end of the hydraulic cylinder and the oil inlet. The pressure of the rod end of the hydraulic cylinder is regulated by the first overflow valve YLF1 and the pressure reducing valve JYF3, and the pressure P is set by the pressure reducing valve JYF3 and the first overflow valve YLF1.

5. The hot rolling roll balancing hydraulic control system according to claim 1, characterized in that The described throttle speed control circuit includes a two-way throttle valve arranged between the rodless cavity of the hydraulic cylinder and the oil inlet. Through the described two-way throttle valve, the lifting or lowering speed of the upper backup roll is controlled.

6. A control method for a hydraulic control system for hot rolling roll balance as described in claim 1, characterized in that: 1) Calculate the total balance weight of the upper backup roll system: 2) Calculate the hydraulic balance force of the upper backup roll: 3) Adopt over-balance force protection control for the roll to control the total balance force of the oil cylinders in the upper backup roll system; 4) Through the control of the roll balance hydraulic system, realize the balance function between the rodless cavity and the rod end cavity, realize the lifting function of the upper backup roll, and realize the rapid lowering function of the upper backup roll.

7. The control method of the hot rolling roll balance hydraulic control system according to claim 6, characterized in that The described total balance weight of the upper backup roll system includes the sum of the weight of the backup roll, the weight of the WS bearing housing, the weight of the DS bearing housing, the weight of all liners of the bearing housing, the weight of two oil film bearings and two thrust bearings, and the weight of the locking and end covers.

8. The control method of the hot rolling roll balance hydraulic control system according to claim 6, characterized in that The described hydraulic balance force of the upper backup roll is: F 总 = k × G 总 Where: K is the overbalance coefficient of the backup roll system; F 总 is the total balance force of the oil cylinder; G 总 is the total weight of the backup rolls; The value range of k is 1.1 - 1.

35.

9. The control method of the hot rolling roll balance hydraulic control system according to claim 6, characterized in that The total balance force of the oil cylinders in the upper backup roll system is calculated according to the following formula: Where: D is the diameter of the cylinder barrel of the oil cylinder, d is the diameter of the piston rod of the oil cylinder, p1 is the pressure of the rodless cavity of the oil cylinder, p2 is the pressure of the rod end cavity of the oil cylinder, and n is the number of oil cylinders.

10. The control method of the hot rolling roll balance hydraulic control system according to claim 6, characterized in that The balance function between the rodless cavity and the rod end cavity is realized through the following control process of the upper backup roll balance hydraulic circuit: The pressure of the rodless cavity of the hydraulic cylinder is regulated by the first overflow valve YLF1 or the second overflow valve YLF2 of the rodless cavity pressure regulating circuit, and the pressure of the rod end cavity of the hydraulic cylinder is regulated by the first overflow valve YLF1 and the pressure reducing valve JYF3 in the rod end cavity pressure regulating circuit to ensure the pressure difference between the two cavities of the oil cylinder, so as to improve the balance force and realize the balance function of the upper backup roll system; At the same time, after the hydraulic oil is decompressed by the pressure reducing valve JYF3 and the pressure is maintained by the first overflow valve YLF1 through the oil inlet, it enters the rod end cavity of the hydraulic cylinder through the second solenoid valve DCF2, and the hydraulic oil in the rodless cavity passes through the oil inlet to the first solenoid valve DCF1, and after being regulated by the two overflow valves of the rodless cavity pressure regulating circuit, it enters the rodless cavity, thereby realizing the "high pressure" state of the rodless cavity and the "low pressure" state of the rod end cavity under the balanced state.

11. The control method of the hot rolling roll balance hydraulic control system according to claim 6, characterized in that The realization of the lifting function of the upper backup roll is achieved through the following control process of the upper backup roll balance hydraulic circuit: Energize the solenoid valve A end coil of the second solenoid valve DCF2, energize the solenoid valve B end coil of the first solenoid valve DCF1, and energize the solenoid valve A end coil of the third solenoid valve DCF3. The pressure in the rodless chamber of the hydraulic cylinder is regulated to a high pressure by the overflow valve in the rodless chamber pressure regulating circuit, and at the same time, the flow rate of the hydraulic oil is restricted through the throttle speed regulating circuit to control the rising speed of the backup roll; the pressure in the rod chamber is regulated to a low pressure state by the overflow valve YLF1 and the pressure reducing valve JYF3 in the rod chamber pressure regulating circuit. When the pressing device rises rapidly, the backup roll is lifted together to realize the lifting function of the upper backup roll. At the same time, the hydraulic oil is reduced in pressure by the pressure reducing valve JYF3 and kept under pressure by the overflow valve YLF1 through the oil inlet, and then enters the rod chamber of the hydraulic cylinder through the second solenoid valve DCF2. The hydraulic oil in the rodless chamber passes through the oil inlet to the third solenoid valve DCF3, passes through the throttle speed regulating circuit, and then enters the rodless chamber after being regulated by the two overflow valves in the rodless chamber pressure regulating circuit. The upper backup roll rises according to the speed adjusted by the throttle speed regulating circuit to avoid excessive impact on the rolling mill due to too fast rising speed.

12. The control method of the hot rolling roll balance hydraulic control system according to claim 6, characterized in that The rapid descent function of the upper backup roll is realized through the following control process of the balance hydraulic circuit of the upper backup roll: Energize the solenoid valve B end of the second solenoid valve DCF2, energize the solenoid valve B end of the first solenoid valve DCF1, and energize the solenoid valve B of the third solenoid valve DCF3. At this time, the oil return pressure in the rodless chamber of the hydraulic cylinder is 0, and the flow rate of the hydraulic oil is restricted through the throttle speed regulating circuit to control the descent speed of the backup roll; at this time, the rod chamber of the hydraulic cylinder directly receives oil from the oil inlet and is in a high-pressure state, thereby realizing the rapid descent function of the upper backup roll. At the same time, the hydraulic oil directly enters the rod chamber of the hydraulic cylinder through the second solenoid valve DCF2, and the hydraulic oil in the rodless chamber of the hydraulic cylinder passes through the throttle speed regulating circuit and returns to the oil return port through the third solenoid valve DCF3. The descent speed is adjusted through the throttle speed regulating circuit to prevent damage to the backup roll due to too fast descent speed.

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