A method for accurately adjusting the clamping force of a continuous casting crystallizer and a clamping device

Abstract

The application discloses a continuous casting crystallizer clamping force accurate adjustment method and clamping device, and belongs to the technical field of metallurgical continuous casting equipment. The device comprises a piston rod, a cylinder body, a disc spring group sleeved on the piston rod, and an insert plate arranged between the outer end surface of the cylinder body and an inner arc locking nut. A gap is arranged between the insert plate and the outer end surface of the cylinder body, the gap is eliminated after the clamping force is normally established, and the insert plate is allowed to contact the cylinder body to form a standby force transmission path when the disc spring fails. During adjustment, the hydraulic oil pressure is calculated according to the target pre-tightening force, the disc spring group is compressed by the pressure oil, and the oil pressure is released after the insert plate is inserted and the nut is locked, so that the pre-compression state is accurately locked. The application combines hydraulic setting and mechanical locking, and realizes complete passive safety protection function by utilizing the gap, so that the setting accuracy, multi-point consistency and equipment intrinsic safety level of the clamping force are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of metallurgical continuous casting equipment technology, specifically to a method and clamping device for precise adjustment of clamping force in a continuous casting crystallizer, which is particularly suitable for the continuous casting process of ultra-wide stainless steel slabs where the uniformity and safety of clamping force are extremely important. Background Technology

[0002] In the continuous casting process of slabs, the crystallizer is a key piece of equipment for initially solidifying high-temperature molten steel into a slab shell. Its inner cavity is surrounded by an inner arc-shaped wide surface, an outer arc-shaped wide surface, and narrow surfaces on both sides. To prevent the static pressure of the molten steel from causing the wide surfaces to open and resulting in steel leakage, a clamping mechanism must be used to apply a stable and uniform clamping force to the wide surfaces.

[0003] Currently, most mainstream crystallizer clamping mechanisms employ disc spring assemblies to provide elastic clamping force, supplemented by hydraulic cylinders for auxiliary adjustment. Traditionally, the preload of the disc springs is controlled indirectly by adjusting the compression height of the disc spring assembly. This approach suffers from two fundamental drawbacks.

[0004] First, due to the unavoidable thickness tolerances and stiffness variations in the disc spring manufacturing process, coupled with the deterioration of material properties after long-term use, the method of indirectly controlling the preload by controlling the compression height cannot accurately guarantee that the actual preload of each set of disc springs is consistent with the target value. When the crystallizer has multiple clamping points at the top and bottom, the unevenness of the preload at each point will directly lead to irregular deformation of the crystallizer cavity, seriously affecting the surface quality of the cast billet, and even causing steel leakage accidents.

[0005] Second, these traditional devices lack a passive safety protection mechanism against accidental failure of the disc spring assembly. In operation, if a disc spring breaks due to fatigue or corrosion, the clamping force will be lost instantly or drop significantly. The system does not have any automatic backup force transmission path that does not require external power, posing a significant safety hazard.

[0006] To address the issue of preload accuracy, the industry has seen attempts to use hydraulic thrust to directly compress the disc spring to the target force value, followed by mechanical locking of the piston rod position. While this method does improve preload setting accuracy, its safety features remain similar to traditional devices. The locking structure's function is limited to maintaining the preload, relying entirely on the intact elasticity of the disc spring and lacking the ability to passively take over the load in the event of disc spring failure. When the disc spring assembly fails due to fatigue or corrosion, the entire system lacks an automatically triggered protection mechanism that requires neither electrical signals nor hydraulic power, thus failing to prevent complete loss of clamping force.

[0007] Therefore, the core technical problem that urgently needs to be solved in this field is: how to design a clamping device and its corresponding method that can set and maintain the clamping force with high precision and high consistency, while also integrating a completely passive safety protection function that does not require any external intervention, and can automatically switch to rigid support at the moment the disc spring fails to prevent the clamping force from being completely lost. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a method and clamping device for precise adjustment of clamping force in a continuous casting crystallizer.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0010] This invention provides a device for precisely adjusting the clamping force of a continuous casting crystallizer.

[0011] The device includes a piston rod, a cylinder, a disc spring assembly, and a mounting plate. The cylinder is fixed to the first fixed back plate on the inner arc of the wide face of the crystallizer. The disc spring assembly is fitted onto the piston rod and housed inside the cylinder. For ease of description, the annular chamber near the front end cover in the inner cavity of the cylinder is referred to as the rod chamber, which is the chamber in which pressurized oil pushes the piston rod to compress the disc spring assembly.

[0012] The insert plate is positioned between the outer end face of the cylinder and an inner arc locking nut. For ease of description, the contact interface between the inner plane of the insert plate and the outer end face of the cylinder is referred to as the insert plate-clamping cylinder mating surface.

[0013] The core structural feature of this device is the gap between the insert plate and the clamping cylinder contact surface. This gap is not a simple assembly gap or manufacturing tolerance, but is given a specific functional configuration: after the clamping force is properly established, the gap is eliminated, and the insert plate and the clamping cylinder contact surface are in contact but do not bear the main load; when the disc spring assembly fails unexpectedly, the gap allows the insert plate and the clamping cylinder contact surface to immediately form rigid contact, thereby constructing a backup rigid force transmission path in addition to the elastic force transmission path.

[0014] The ingenuity of this design lies in the fact that the same gap plays drastically different yet equally important roles in different operating states of the device. During the preload adjustment phase, it provides operational space for precise setting; during normal operation, it is eliminated to ensure the insert plate does not bear alternating loads, avoiding fatigue accumulation; in the extreme condition of disc spring failure, it automatically triggers, transforming the insert plate from an idle component into a rigid support, achieving completely passive safety protection. A simple gap configuration solves three key issues: precise preload adjustment, long insert plate life, and failure protection.

[0015] This device creates an inherent working mechanism of "elastic force transmission under normal operating conditions and rigid protection under failure conditions" by setting a gap with specific functions between the insert plate and the cylinder. Compared with the existing technology that uses locking elements only for position fixing, this invention gives the same mechanical element two completely different functional roles, and the switching process relies entirely on the natural change of mechanical balance, without the need for any sensors, controllers or external power intervention, which significantly improves the intrinsic safety level of the equipment.

[0016] Furthermore, the rigid force transmission path constructed in this invention operates with a completely passive and automatically triggered characteristic. Before the disc spring assembly fails, this path is physically disconnected due to the presence of the gap; when the disc spring assembly fails, causing the piston rod to experience a micron-level rebound displacement, this displacement is exactly equal to the gap value, thereby automatically and without delay pressing the insert plate against the outer end face of the cylinder body, seamlessly switching the force flow from the failed elastic path to this rigid path. This process requires no sensors, controllers, or external power intervention, representing an inherently safe design based on pure mechanical structure and mechanical balance. Furthermore, the insert plate is defined as a plate-like structure with a U-shaped opening, allowing direct lateral insertion around the piston rod without disassembling the piston rod or any axially mounted components.

[0017] The U-shaped opening design makes the installation and removal of the insert plate extremely convenient. During crystallizer maintenance and clamping force recalibration, operators can quickly insert and remove the insert plate in a confined space, significantly shortening the operation time and improving equipment maintenance efficiency.

[0018] Furthermore, the device also includes the inner arc locking nut. The inner arc locking nut is screwed onto the piston rod, with its inner end face tightly abutting the outer end face of the insert plate.

[0019] The inner arc locking nut provides a reliable and adjustable axial positioning reference for the insert plate. After the hydraulic preload is set, simply tightening the nut to press the insert plate in place encloses the enormous elastic restoring force of the disc spring assembly within the internal force system composed of the cylinder and piston rod, achieving stable and reliable mechanical locking.

[0020] Furthermore, the device also includes an outer arc preload nut and an outer arc anti-loosening nut. The outer arc preload nut is screwed onto the outer arc side end of the piston rod, serving as an operating element for establishing the final clamping force on the wide face of the crystallizer. The outer arc anti-loosening nut is disposed close to the outer end face of the outer arc preload nut, with both end faces touching.

[0021] The outer arc preload nut converts the preload inside the piston rod into the actual clamping force on the wide copper plate of the crystallizer. Together with the outer arc anti-loosening nut, it forms the first-stage anti-loosening structure, which can effectively prevent the single nut from loosening due to slight movement under continuous vibration conditions, thus providing a preliminary guarantee for the long-term stability of the clamping force.

[0022] Furthermore, the device is equipped with an outer arc positioning nut and an outer arc anti-loosening nut II. The outer arc positioning nut is screwed onto the outermost end of the piston rod, and the outer arc anti-loosening nut II is set tightly against the outer arc positioning nut, forming a second-stage anti-loosening structure.

[0023] By introducing additional positioning nuts and a second anti-loosening nut, the entire outer arc side locking system constitutes a multi-layered anti-loosening mechanism. Even when the continuous casting machine is subjected to harsh operating conditions of thermal cycling and low-frequency vibration, this progressive anti-loosening design ensures that the clamping force does not experience measurable attenuation, thus guaranteeing the operational stability of the equipment throughout the entire maintenance cycle.

[0024] The present invention also provides a method for precisely adjusting the clamping force of a continuous casting crystallizer using the above-described device.

[0025] The core concept of this method is to convert the "force" that is difficult to measure and control directly in traditional technology into the "pressure" that can be measured and controlled with high precision in modern hydraulic technology. Then, by utilizing the uniformity of Pascal's principle, the requirement to set a target force is transformed into the precise setting of the output pressure of the hydraulic system.

[0026] The method specifically includes the following operations.

[0027] First, three basic parameters are obtained: the preload of the disc spring assembly as required by the process, the piston rod diameter, and the cylinder inner diameter. Based on these three parameters, the annular effective pressure-bearing area of ​​the rod cavity is calculated. Then, the required hydraulic oil pressure within the rod cavity is obtained by dividing the preload by this area. This calculation step converts the force requirement into a pressure command that the hydraulic system can execute.

[0028] Next, pressurized oil is introduced into the rod chamber according to the calculated pressure value. The thrust generated by the hydraulic oil on the piston annular end face pushes the piston rod to move, compressing the disc spring assembly. The elastic restoring force generated by the disc spring assembly during compression gradually increases. When the elastic force and the hydraulic thrust reach static equilibrium, the piston rod stops moving. At this time, the actual preload stored in the disc spring assembly is exactly equal to the set preload value.

[0029] Then, while maintaining an absolutely stable hydraulic oil pressure within the rod cavity, the insert plate is inserted into the space formed between the outer end face of the cylinder body and the inner arc locking nut. One side of the insert plate rests against the outer end face of the cylinder body in the mating surface between the insert plate and the clamping cylinder, while the other side is pressed down by the inner arc locking nut.

[0030] Finally, the hydraulic pressure in the rod chamber is released. After the hydraulic thrust is removed, the elastic restoring force of the disc spring assembly tends to cause the piston rod to spring back, but this tendency is immediately blocked by the inner arc locking nut and the insert plate. The force of the disc spring assembly is transmitted to the cylinder through the piston rod, the inner arc locking nut, and the insert plate, forming a closed internal force balance system, thereby precisely locking the pre-compression state of the disc spring assembly.

[0031] This method fundamentally avoids the influence of individual disc spring stiffness differences and frictional resistance uncertainties. Regardless of the manufacturing tolerances of the disc springs, each set of disc springs achieves balance and locks under the exact same hydraulic thrust, ensuring that the preload setting closely matches the target value. Furthermore, this method elevates the adjustment accuracy from millimeter-level displacement measurement in traditional height control methods to direct force calibration relying on hydraulic pressure sensors, typically improving accuracy by an order of magnitude.

[0032] Furthermore, after the disc spring assembly is precisely locked in its pre-compression state, the process also includes establishing the actual clamping force between the inner and outer arcs of the wide surface.

[0033] The specific operation of this process is as follows: tighten the outer arc preload nut, apply an outward pulling force to the piston rod through the threaded pair, tighten the piston rod until the gap that previously existed between the insert plate and the clamping cylinder contact surface is completely eliminated; then, tighten the outer arc anti-loosening nut one in sequence to fix the outer arc preload nut, tighten the outer arc positioning nut to the predetermined position, and tighten the outer arc anti-loosening nut two to lock the outer arc positioning nut, thus completing multiple anti-loosening measures.

[0034] The process uses gap elimination as a clear and visible operational endpoint. Operators do not need to rely on experience or complex torque control; they only need to observe or use a feeler gauge to confirm that the gap is zero to precisely terminate the tightening action. This avoids insufficient clamping force due to undertightening, and also avoids overtightening causing the insert plate to bear additional loads and change the preset clamping force, ensuring the non-destructive and accurate conversion.

[0035] Furthermore, the above method clarifies the behavior patterns of the insert plate and the gap under two states: normal operation of the device and disc spring failure.

[0036] Under normal operating conditions, the clamping force is entirely provided by the disc spring assembly. Although the insert plate contacts the outer end face of the cylinder at the contact surface between the insert plate and the clamping cylinder, it is not the main load-bearing link of the force flow. In fact, it is in a nearly idle standby state and does not bear alternating tensile loads, so there is almost no accumulation of fatigue damage.

[0037] When the disc spring assembly fails unexpectedly and the elastic support is lost instantaneously, the slight rebound displacement of the piston rod under the residual tension will be immediately suppressed by the zero-gap state between the insert plate and the clamping cylinder contact surface, and the two will instantly transform into a tight, rigid contact. The tension of the piston rod is transmitted directly to the cylinder body through the inner arc locking nut and the insert plate in a rigid manner, forming a backup force transmission path to replace the failed elastic path.

[0038] This design achieves a completely passive, powerless, and real-time safety protection function. The insert plate automatically switches from an "idle component" to a "rigid support" the instant the disc spring fails. The entire process requires no sensor detection, electrical control, or hydraulic power; it relies solely on changes in mechanical state and mechanical clearance limiting. This inherently safe design significantly reduces the risk of sudden pressure loss, the most dangerous aspect of continuous casting production, providing operators with a critical time window to detect anomalies and take safety measures.

[0039] Furthermore, the calculation process for the required hydraulic oil pressure inside the rod cavity was further refined.

[0040] The calculation process is as follows: obtain the set disc spring preload value, piston rod diameter value, and cylinder inner diameter value; subtract the piston rod cross-sectional area from the cylinder inner cavity cross-sectional area to obtain the annular effective pressure area of ​​the rod cavity; divide the set disc spring preload value by the effective pressure area to obtain the required hydraulic oil pressure value.

[0041] It provides a clear and easy-to-implement engineering calculation method. Only basic dimensional measurement tools and calculation capabilities are required on-site to independently complete all parameter conversions, without relying on dedicated calculation software or calibration curves provided by equipment manufacturers. This makes the method highly universal and practical for on-site operation.

[0042] Furthermore, the above method is used for scenarios where multiple clamping points are precisely adjusted at the upper and lower parts of the crystallizer.

[0043] In this application scenario, the operation procedure is as follows: for each clamping point, the aforementioned preload adjustment method is executed independently in sequence, and the same and constant calculated hydraulic oil pressure value is used throughout the entire process of adjusting all clamping points. It is strictly forbidden to adjust the output pressure setting of the hydraulic pump station midway.

[0044] Because all clamping points are subjected to identical hydraulic pressure conditions for force balance and mechanical locking, this inherently ensures that each disc spring assembly is compressed to the exact same state, storing a completely consistent preload. This method, starting with the uniformity of the "cause"—the applied conditions—naturally achieves consistency in the "effect"—the output force value, completely solving the long-standing problem of force dispersion at multiple clamping points that traditional methods for controlling compression height have been unable to address. For ultra-wide slab crystallizers, the uniformity of the internal cavity directly determines the quality of the cast slab; this high degree of consistency in force values ​​across multiple points has significant industrial value. Attached Figure Description

[0045] Figure 1 This is a schematic diagram showing the distribution of clamping points in a crystallizer for applying the present invention.

[0046] Figure 2 This is a schematic diagram of the clamping mechanism according to an embodiment of the present invention.

[0047] Figure 3a This is a schematic diagram of the precise adjustment stage of the preload force in an embodiment of the present invention.

[0048] Figure 3b This is a schematic diagram of the preload locking stage in an embodiment of the present invention.

[0049] Figure 4 This is a schematic diagram of the clamping force establishment stage of the wide-face inner and outer arcs in an embodiment of the present invention.

[0050] Explanation of reference numerals in the attached figures: 1. Piston rod; 2. Cylinder body; 3. Disc spring assembly; 4. Insert plate; 5. Inner arc locking nut; 6. Outer arc preload nut; 7. Outer arc anti-loosening nut one; 8. Outer arc positioning nut; 9. Outer arc anti-loosening nut two; 11. First fixed back plate; 12. Second fixed back plate; 13. Rod cavity; 14. Insert plate and clamping cylinder contact surface; 15. Outer arc wide surface; 16. Inner arc wide surface; 17. Left narrow surface; 18. Right narrow surface. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of this invention and are not intended to limit the scope of protection of this invention.

[0052] Example 1 This embodiment describes in detail the specific structure and working mechanism of the clamping force precision adjustment device of the present invention. Figure 1A typical crystallizer structure using this device is shown. The crystallizer has an outer arc-shaped wide surface 15, an inner arc-shaped wide surface 16, a left narrow surface 17, and a right narrow surface 18, which together form an inner cavity to accommodate molten steel. To ensure the stability of the inner cavity shape, four clamping points, A, B and C, D, are respectively provided at the upper and lower parts of the crystallizer. The clamping device of the present invention is independently provided at each clamping point.

[0053] like Figure 2 As shown, the core components of the clamping device include piston rod 1, cylinder 2, disc spring assembly 3, and insert plate 4. The structure, material, function, and interconnection of each component will be described in detail below.

[0054] The piston rod 1 is made of alloy structural steel with excellent hardenability and heat resistance through integral forging and precision machining. For example, 42CrMo or a similar grade material can be used. The surface is hard chrome plated or nitrided to enhance wear resistance and corrosion resistance. One end of the piston rod 1 is designed with a piston head, and multiple sealing grooves are opened on the outer circumference of the piston head for installing combined seals and wear-resistant guide rings, forming a precision dynamic seal with the inner cavity of the cylinder 2. The other end of the piston rod 1 is machined with a long section of trapezoidal precision external thread for installing various nuts. The piston rod 1 is the core force transmission element that runs through the entire device and is the only one that simultaneously bears tensile and compressive loads.

[0055] The cylinder body 2 is a cylindrical structure formed by integral forging. It is firmly fixed to the first fixed back plate 11 with a wide inner arc by multiple high-strength bolts evenly distributed along the circumference. The front end cover of the cylinder body 2 has a precision through hole in the center for the piston rod 1 to pass through. The through hole is also equipped with a guide sleeve and a dustproof sealing ring. The inner end face of the front end cover is machined with a hardened annular shoulder, which serves as the fixed support surface for the disc spring assembly 3. Two sets of oil passages are drilled inside the cylinder wall of the cylinder body 2, leading out to the rod chamber oil port and the rodless chamber oil port near the front end cover and the bottom of the cylinder, respectively, for connecting to an external hydraulic pump station. For ease of description later, the annular chamber formed by the piston head and located near the front end cover in the inner cavity of the cylinder body 2 is called the rod chamber 13. The rod chamber 13 is the working chamber in which the pressurized oil pushes the piston rod to compress the disc spring assembly. The inner working surface of cylinder 2 is honed to achieve a surface roughness of less than Ra0.2 micrometers and a roundness tolerance of H7 level, in order to ensure sealing life and minimize the frictional resistance of piston movement.

[0056] Disc spring assembly 3 consists of dozens of disc springs arranged in a specific pairing or stacking configuration. The specific number of springs and the arrangement are determined based on the target clamping force and the allowable deformation space. The disc springs are made of spring steel with excellent creep resistance and fatigue resistance, such as 50CrVA, and are subjected to isothermal quenching and high-pressure treatment. Disc spring assembly 3 is integrally mounted on the piston rod 1 and located within the inner cavity of cylinder 2. One end rests against the shoulder of piston rod 1 (when the piston head and rod are designed separately, the shoulder serves as a step at the transition between the two; when designed as a single unit, the inner end face of the piston head acts as the shoulder), and the other end rests against the inner shoulder of the front end cover of cylinder 2. Disc spring assembly 3 is the initial energy storage and release element for clamping force, and its load-deformation characteristics exhibit high linearity within the working range, providing favorable conditions for accurate conversion between force and displacement.

[0057] The insert plate 4 is the core innovative component that distinguishes this invention from existing technologies. In this embodiment, the insert plate 4 is made of high-strength mold steel (such as Cr12MoV or a similar grade) through wire cutting and precision grinding. The overall shape of the insert plate 4 is a rectangular plate with a thickness denoted as T. One side has a U-shaped through opening with a width slightly larger than the diameter of the threaded section of the piston rod 1. This opening allows the insert plate 4 to be pushed directly into place from the side without having to be fitted from the end of the piston rod 1. The insert plate 4 is positioned between the outer end face of the cylinder body 2 and the inner arc locking nut 5. For ease of description later, the contact interface between the inner plane of the insert plate 4 and the outer end face of the cylinder body 2 is referred to as the insert plate and clamping cylinder contact surface 14. During the preload adjustment stage, a gap is intentionally set between these contact surfaces; after the clamping force is established, this gap is eliminated, and the contact surfaces are in a micro-contact state; when the disc spring assembly fails, the contact surfaces become rigid load-bearing contacts. The switching of the bonding surface state is the core of the working mechanism that realizes "elastic force transmission under normal working conditions and rigid protection under failure conditions".

[0058] A fundamental structural feature of this device is that the insert plate and the clamping cylinder contact surface 14 are not always in tight contact, but rather a gap is intentionally provided. In the initial state after the preload is set and locked, the value of this gap is determined through meticulous engineering calculations. In this embodiment, it is determined based on the following three factors: first, the axial thermal expansion difference between the cylinder 2 and the piston rod 1 under the maximum operating temperature difference; second, the instantaneous rebound displacement of the piston rod 1 that may occur under the most unfavorable single-piece fracture condition of the disc spring assembly 3; and third, a safety margin to ensure that thermal expansion under normal operating conditions will not mistakenly press the insert plate 4 tightly. These three factors combine to form the final gap value, which in this embodiment can be from 0.3mm to 1.0mm, preferably 0.5mm. The existence of this gap and its precise value are the structural basis for realizing the dual working mechanism of "elastic force transmission under normal operating conditions and rigid protection under failure conditions" described later.

[0059] The inner arc locking nut 5 is screwed onto the threaded section of the piston rod 1, located on the outer side of the insert plate 4. The inner end face of the inner arc locking nut 5 is precision-machined, with good flatness, enabling uniform surface contact with the outer surface of the insert plate 4. A threaded hole is drilled radially in the nut to accommodate a set screw for added anti-loosening. Its core function is to reliably press the insert plate 4 during preload setting operations, thereby mechanically locking the axial position of the piston rod 1.

[0060] The outer arc preload nut 6 is screwed onto the threaded end of the second fixed back plate 12, which extends from the wide outer arc of the piston rod 1. This nut has a thick design and a large bearing end face to withstand the high axial tensile force when the clamping force is established. The outer arc anti-loosening nut 7 is screwed tightly against the outer end face of the outer arc preload nut 6, and the two end faces are top to top, forming the first-level anti-loosening structure.

[0061] The outer arc positioning nut 8 is screwed onto the outermost end of the piston rod 1. Its position can be adjusted as needed, serving to assist in positioning the screwing depth of the outer arc preload nut 6. The outer arc anti-loosening nut 9 is screwed tightly against the outer end face of the outer arc positioning nut 8, forming a second-stage anti-loosening structure.

[0062] The aforementioned four-stage nuts constitute a complete outer arc-side anti-loosening chain. In the continuous casting production environment, which is characterized by alternating hot and cold temperatures and low-frequency mechanical vibrations, this multi-stage anti-loosening design significantly improves the long-term clamping force retention capability compared to a single nut or a simple double-nut structure.

[0063] Example 2 This embodiment details a method for precisely setting preload, the core of which lies in "hydraulic setting and mechanical locking"—utilizing the high controllability of liquid medium pressure and the uniformity of Pascal's principle to transform preload, a mechanical quantity that is difficult to measure directly, into a pressure parameter that can be precisely controlled within a hydraulic system. Please refer to [link to relevant documentation]. Figure 3a and Figure 3b .

[0064] First, the engineering calculation of the target pressure value is performed. Let F_N be the target disc spring preload at a certain clamping point, calculated by the process department based on the static pressure of molten steel and the structural parameters of the crystallizer. Using a calibrated inside micrometer and vernier caliper, the diameter d of piston rod 1 and the diameter D of the inner cavity of cylinder 2 are accurately measured at room temperature, and the units are converted to meters. The effective pressure-bearing area of ​​the rod cavity 13 refers to the area on the piston head within the annular region where hydraulic oil can generate thrust. Its size is equal to the cross-sectional area of ​​the inner cavity of the cylinder minus the cross-sectional area of ​​the piston rod. The calculation formula is A equal to π divided by 4, then multiplied by the area within parentheses (D squared minus d squared).

[0065] According to the basic principles of fluid mechanics, the hydraulic pressure within a closed hydraulic chamber acts with the same intensity on all contact surfaces. The thrust F_hyd generated by the hydraulic oil on the piston is equal to the system pressure P multiplied by the effective pressure-bearing area A. When the piston reaches static equilibrium, this hydraulic thrust is exactly offset by the elastic restoring force F_N of the disc spring assembly, i.e., F_N equals F_hyd, which is equal to P multiplied by A. Therefore, it can be deduced that the required hydraulic oil pressure P is equal to F_N divided by A. This calculation is performed independently before each adjustment and serves as the baseline value for hydraulic system pressure regulation.

[0066] Next, perform the hydraulic compression operation. Connect the high-pressure hydraulic pump station to the rod chamber port on the side wall of cylinder 2 via a high-pressure hose and a self-sealing quick-connect coupling. This port is connected to the rod chamber 13. Ensure that the rodless chamber port is connected to the return line. After starting the hydraulic pump, slowly adjust the relief valve or proportional pressure regulating valve to allow the system pressure to rise steadily. The operator must closely monitor the readings of the calibrated high-precision pressure sensor or pressure gauge. When the pressure accurately reaches the calculated value P, maintain system stability. At this point, pressurized oil continues to enter the rod chamber 13, and the piston rod 1 moves axially inward under the drive of the thrust F_N, compressing the disc spring assembly 3.

[0067] The deformation of disc spring assembly 3 is a gradual process. Initially, when the deformation is large, the elastic restoring force increases relatively slowly; after entering the working stage, the force and deformation have a nearly linear relationship. As compression continues, the difference between the elastic restoring force accumulated inside the disc spring assembly and the hydraulic thrust gradually decreases, and the movement speed of piston rod 1 also decreases accordingly. When the elastic restoring force increases to the point where it is equal to and opposite to F_N, the force system reaches complete equilibrium, and the movement of piston rod 1 stops. At this equilibrium point, the load borne by disc spring assembly 3—that is, the preload that will be output later—is precisely equal to the target value F_N required by the process. The accuracy of this force value mainly depends on the precision of the hydraulic system's pressure control. Modern industrial-grade hydraulic components, combined with precision pressure sensors, can control the pressure control error to within one-thousandth of the full scale. Therefore, the accuracy of the force value calculated in this way is far superior to the traditional method of relying on measuring the compression height.

[0068] Then, the mechanical locking operation is performed. This is a crucial step in converting the temporary action of hydraulic force into a permanent mechanical state. With the hydraulic system maintaining an absolutely stable pressure P, the operator observes a noticeable space between the inner arc locking nut 5 and the outer end face of the cylinder 2 due to the inward movement of the piston rod 1. A pre-prepared insert plate 4 with a precise thickness T, according to the clearance requirements, is selected. Holding the insert plate 4, the U-shaped opening is aligned with the piston rod 1, and it is smoothly pushed into the space from the side until the inner plane of the insert plate 4 is evenly fitted with the outer end face of the cylinder 2. At this point, the insert plate and the clamping cylinder contact surface 14 are in a temporary contact state, but because the hydraulic thrust maintains the piston rod position, the contact surface has not yet experienced the elastic restoring force of the disc spring assembly. Since the hydraulic thrust firmly holds the piston rod 1 in its current position, the insert plate 4 experiences almost no compressive force during insertion.

[0069] Next, use a special bent-end wrench to tighten the inner arc locking nut 5 towards the cylinder body 2, so that its inner end face is firmly pressed against the outer side of the insert plate 4. During the tightening process, it is necessary to keep the insert plate 4 and the end face of the cylinder body 2 in good contact and prevent any misalignment. After locking in place, the set screw on the inner arc locking nut 5 can be slightly tightened as needed.

[0070] Finally, hydraulic release is performed. The pressure relief valve is slowly opened, allowing the pressurized oil in the rod chamber 13 to flow smoothly back to the oil tank, and the pressure gauge reading gradually returns to zero. The instant the hydraulic thrust F_N disappears, the enormous elastic restoring force of the disc spring assembly is immediately released, attempting to push the piston rod 1 axially outward. However, this pushing tendency is immediately blocked by the mechanical lock formed by the inner arc locking nut 5 and the insert plate 4. The elastic force of the disc spring assembly 3 is transmitted through the shoulder of the piston rod 1, the rod body of the piston rod 1, the inner arc locking nut 5, and the insert plate 4, and then through the insert plate and the clamping cylinder contact surface 14, and is sealed on the front end cover of the cylinder body 2, forming a closed internal force system. At this point, the pre-compression state of the disc spring assembly 3 is precisely and permanently locked, and the preload setting operation is completed.

[0071] Example 3 After the disc spring assembly preload is precisely locked, the device is capable of outputting the target force value, but the actual clamping force between the wide faces of the crystallizer has not yet been established. This embodiment details the complete operation process for establishing this clamping force. Please refer to... Figure 4 .

[0072] At this point, the cylinder body 2, piston rod 1, disc spring assembly 3, insert plate 4, and inner arc locking nut 5 have been assembled into an integrated component. The cylinder body 2 is firmly fixed to the first fixed back plate 11 of the wide inner arc by bolts. The end of the piston rod 1 with external threads passes through the inner cavity of the crystallizer and extends out from the central through hole of the second fixed back plate 12 of the wide outer arc. The wide inner arc copper plate, outer arc copper plate, and left and right narrow copper plates of the crystallizer have all been placed in place according to the thickness dimensions required by the process. The spacing between the wide copper plates is precisely defined by the width of the narrow copper plates.

[0073] The first step in establishing clamping force is to screw the outer arc preload nut 6 into the exposed threaded end of the piston rod 1, but not to tighten it completely yet, only to make the end face of the nut lightly contact the outer side of the second fixed back plate 12 with the wide outer arc.

[0074] The second step involves applying a steady and continuous torque to the outer arc preload nut 6 using a hydraulic torque wrench or bolt tensioner, causing it to screw inward, i.e., toward the inner cavity of the crystallizer. As the end face of the outer arc preload nut 6 presses tightly against the outer side of the second fixed back plate 12, the continued tightening action will generate an outward pulling force on the piston rod 1 through the threaded pair, i.e., away from the inner cavity of the crystallizer.

[0075] This pulling force is transmitted along the piston rod 1 to the inner arc side, attempting to pull the inner arc locking nut 5 and the insert plate 4 assembly outward. However, the cylinder body 2 is firmly fixed to the first fixed back plate 11, restricting this tendency to move. As a result, the mechanical effect of tightening the outer arc preload nut 6 is essentially to force a reduction in the distance between the first fixed back plate 11 of the wide inner arc and the second fixed back plate 12 of the wide outer arc. This reduction in distance directly manifests as an increase in the clamping force of the inner arc wide copper plate and the outer arc wide copper plate on the middle narrow copper plate, that is, the required clamping force of the crystallizer.

[0076] The third step is the most crucial termination judgment in the entire operation. In the pre-tightened locked state, there is initially a gap of approximately 0.5 mm between the insert plate and the clamping cylinder contact surface 14. As the outer arc pre-tightening nut 6 is continuously tightened, the piston rod 1 is gradually pulled outwards, causing the inner arc locking nut 5 and the insert plate 4 to move outwards synchronously, and the gap value gradually decreases accordingly. The operator needs to continuously monitor the change in the gap between the insert plate and the clamping cylinder contact surface 14 using a feeler gauge set. When a 0.02 mm thick piece of the feeler gauge can no longer be inserted into the gap, it indicates that the gap has been completely eliminated—the insert plate and the clamping cylinder contact surface 14 are just making contact.

[0077] At this point, the tightening of the outer arc preload nut 6 must be stopped immediately. At this critical point, the preload F_N of the disc spring assembly 3 has been fully transferred to the wide surface of the crystallizer, and the clamping force equals the preload, with no loss during the clamping process. If the nut is tightened further at this moment, the additional displacement will no longer be converted into clamping force because the insert plate and the clamping cylinder contact surface 14 are already in contact. Instead, this will cause the insert plate 4 and cylinder 2 to bear unnecessary additional pressure loads, and may even lead to deformation of the insert plate or a change in the preset clamping force. Therefore, "stopping as soon as the gap is eliminated" is the core operating principle for ensuring accurate clamping force establishment.

[0078] Fourth, while maintaining the torque constant, perform multiple anti-loosening locking operations sequentially. First, tighten the outer arc anti-loosening nut 7 until its end face is tightly fitted with the outer end face of the outer arc preload nut 6, forming the first pair of top-locking. Next, tighten the outer arc positioning nut 8 to the predetermined reference position. Finally, tighten the outer arc anti-loosening nut 9 until it aligns with the outer arc positioning nut 8, forming the second pair of top-locking. At this point, the clamping force of the wide-face inner and outer arcs is safely, accurately, and permanently established.

[0079] Example 4 This embodiment specifically illustrates how the insert plate 4 and the gap structure between it and the cylinder 2 automatically achieve a safety protection function under actual working conditions. The unique feature of this protection mechanism is its completely passive nature—it requires no sensor to detect failure, no control system to issue commands, and no hydraulic or pneumatic actuators to operate; it can be accomplished solely through a clever mechanical structure configuration and the natural change in mechanical balance.

[0080] After completing the clamping force establishment operation in Example 3, the device enters its daily service state. At this time, the gap between the insert plate and the clamping cylinder contact surface 14 has been eliminated, and the two are in microscopic contact. However, in terms of force distribution, all the clamping force required by the crystallizer is independently provided by the elastic restoring force of the disc spring assembly 3. The force transmission path is clear and unique: the elastic force of the disc spring assembly 3 acts on the shoulder of the piston rod 1, is transmitted through the rod body of the piston rod 1 to the outer arc preload nut 6 at its outer arc end, and is then applied to the outer arc wide copper plate through the second fixed back plate 12 of the wide outer arc. At the same time, the reaction force generated by the compression of the narrow copper plate is force-sealed through the inner arc wide copper plate, the first fixed back plate 11 of the wide inner arc, the cylinder 2, and other components. In this normal force flow, there is only slight contact between the insert plate and the clamping cylinder contact surface 14. The insert plate 4 and the inner arc locking nut 5 only bear the slight static load caused by their own weight and the slight compressive stress introduced during the tightening process, and are not part of the tensile stress main circuit.

[0081] This "idle" state is deliberately designed and protected. The insert plate 4 does not bear alternating loads for over 99.9% of the equipment's operating cycle, thus preventing the accumulation of fatigue damage. Its material strength and geometric precision can be fully maintained over a very long service life. This is a crucial prerequisite for ensuring reliable operation at critical moments.

[0082] When extreme conditions occur, if one or more disc springs in disc spring assembly 3 break or undergo permanent plastic collapse due to material fatigue, localized stress corrosion, or sudden overload caused by long-term service, the mechanical balance of the entire device is disrupted. The elastic support provided by disc spring assembly 3 is lost or drops sharply at the moment of breakage.

[0083] In traditional clamping devices, the loss of elastic force will directly cause the piston rod to lose unidirectional support. Under the combined action of external static pressure of molten steel and residual tensile stress, the piston rod will rebound rapidly in the inward arc direction, and the clamping force will drop sharply, which may lead to serious consequences.

[0084] In the device of this invention, the rebound motion of the piston rod 1 is suppressed at the initial start-up. The key blocking mechanism is the zero gap that has been eliminated between the insert plate and the clamping cylinder contact surface 14. Because the gap is zero, any micron-level displacement of the piston rod 1 toward the cylinder body 2 will immediately cause substantial, load-bearing rigid contact between the insert plate and the clamping cylinder contact surface 14.

[0085] The force flow path undergoes a fundamental shift at this instant. The original elastic force transmission path is broken due to the failure of the disc spring, and the backup rigid transmission path is immediately activated. The new path is as follows: the tension of the piston rod 1 is transmitted to the inner arc locking nut 5 through its threaded section, and then to the insert plate 4 through the end face of the inner arc locking nut 5. The insert plate 4 then presses directly against the end face of the front cover of the cylinder body 2 through the insert plate and the clamping cylinder contact surface 14, and finally to the first fixed back plate 11 of the inner arc of the wide surface, ultimately acting on the inner arc wide copper plate. Through this path, the clamping force between the wide surfaces of the crystallizer is partially maintained. Although it may be lower than the set value, it is sufficient to prevent the wide surfaces from being opened by the static pressure of the molten steel, fundamentally avoiding catastrophic accidents such as steel leakage.

[0086] The entire switching process is completed automatically within milliseconds, relying entirely on the mechanical limit provided by the gap elimination state, without requiring any response from the electrical or hydraulic systems. This is a truly intrinsically safe design and one of the most significant technical advantages of this invention compared to existing similar devices.

[0087] Example 5 This embodiment provides a complete engineering numerical calculation example to help understand the implementation and accuracy level of this method in the field.

[0088] Taking a super-wide stainless steel slab continuous casting machine being commissioned at a steel plant as an example, its crystallizer is designed with four clamping points. The process requirements for the disc spring preload at the upper clamping points A and B are both 1200 kN, while the requirements for the lower clamping points C and D are both 1500 kN. The clamping devices installed at the upper and lower clamping points have the same structural dimensions.

[0089] First, the inner diameter D of cylinder 2 is measured using an inside micrometer with an accuracy of 0.01 mm. The result is that D equals 150.00 mm, or 0.150 m. Then, the diameter d of piston rod 1 is measured using a micrometer with the same accuracy. The result is that d equals 85.00 mm, or 0.085 m.

[0090] Calculate the annular effective pressure area A of the rod cavity 13: A equals π, which is 3.14159 divided by 4, and then multiplied by the area in parentheses (D squared minus d squared), i.e., 0.7854 multiplied by (0.150 squared minus 0.085 squared), which equals 0.7854 multiplied by (0.0225 minus 0.007225), which equals 0.7854 multiplied by 0.015275, which equals 0.011997 square meters.

[0091] For the upper clamping points A and B, the target preload F_up is equal to 1,200,000 Newtons. The required hydraulic oil pressure P_up is equal to F_up divided by A, that is, 1,200,000 divided by 0.011997, which is equal to 1,000,250,06 Pascals, approximately 100.0 MPa.

[0092] For the lower clamping points C and D, the target preload F_down is equal to 1,500,000 Newtons. The required hydraulic oil pressure P_down is equal to F_down divided by A, that is, 1,500,000 divided by 0.011997, which is equal to 125,031,258 Pascals, approximately 125.0 MPa.

[0093] During on-site adjustment, for the upper clamping points A and B, simply set the output pressure of the hydraulic pump station precisely to 100.0 MPa and maintain it stably, then execute the complete setting process described in Example 2 point by point; for the lower clamping points C and D, adjust the pump station output pressure to 125.0 MPa and execute the same process. Through the above operations, the consistency of preload between clamping points on the same layer and the precise proportional relationship of force values ​​between upper and lower layers can be effectively guaranteed.

[0094] Example 6 This embodiment specifically demonstrates the technical effect achieved by the method of the present invention in ensuring that the preload of multiple clamping points is highly consistent, and clarifies its engineering principle.

[0095] Taking the crystallizer parameters of Example 5 as an example again. For the upper clamping points A and B, the target preload for both is 1200 kN, and the required hydraulic pressure is uniformly 100.0 MPa.

[0096] The operating procedure is as follows. First, connect the hydraulic pump station pipeline to the device at clamping point A, start the pump station, and precisely adjust and lock the system pressure at 100.0 MPa. Throughout this adjustment process, the adjusting valves must remain in their original positions, and it is strictly forbidden to adjust the pressure setpoint again.

[0097] Under a stable pressure of 100.0 MPa, the piston at clamping point A compresses the disc spring assembly under hydraulic thrust until force balance is achieved. At this point, the hydraulic thrust on the piston is precisely equal to 100.0 MPa multiplied by the effective area A, which is 1200 kN. Then, the insert plate is inserted, the inner arc locking nut is tightened, and the pressure is released, completing the setting at point A. The disc spring assembly at point A is locked in a compressed state balanced with the 1200 kN hydraulic thrust.

[0098] Next, the hydraulic lines were disconnected and connected to the device at clamping point B. The key step was to leave the pump station's output pressure setting unchanged, locking it at 100.0 MPa. After pressurization, the disc spring assembly at point B also reached equilibrium and locked under the 100.0 MPa hydraulic thrust. Since the structural dimensions and input pressure are the same, according to the principle of mechanical equilibrium, the preload stored in the disc spring assembly at point B when it reaches equilibrium must also be 1200 kN.

[0099] Similarly, for the lower clamping points C and D, reset and lock the pump station output pressure at 125.0 MPa, and then perform the operations at points C and D in sequence.

[0100] After the above process, the preload at points A and B is a consistent 1200 kN, and the preload at points C and D is a consistent 1500 kN. It is particularly noteworthy that the fundamental reason this method ensures consistent force values ​​at multiple points lies in controlling the consistency of the application conditions, that is, ensuring that all clamping points are in the same hydraulic pressure environment to achieve force balance and locking. Regardless of the stiffness variation of the disc spring assemblies used at each point due to batch differences in manufacturing, and regardless of the slight differences in frictional resistance between the mating surfaces at each point, as long as the external hydraulic thrust is the same, the elastic force inside the disc spring assembly will necessarily be the same at equilibrium. This is a fundamental solution that derives consistency of result from consistency of cause.

[0101] Traditional height control methods rely on operators measuring compression height to ensure consistency at all points. However, due to inherent differences in the force-deformation curves of each disc spring assembly, even with identical compression heights, the actual output preload force remains dispersed. This invention reduces the force dispersion from potentially as high as ±10% or more in traditional methods to a range of ±0.000%, primarily determined by the accuracy of the pressure sensor—a significant leap in precision. Simultaneously, the entire operation process is highly standardized, eliminating the need for repeated trial and error, and increasing work efficiency several times over compared to traditional methods.

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for precisely adjusting the clamping force of a continuous casting crystallizer, characterized in that, include: Piston rod (1); Cylinder body (2), the cylinder body (2) is fixed on the first fixed back plate (11) on the inner arc of the wide surface of the crystallizer; Disc spring assembly (3), which is mounted on the piston rod (1) and housed inside the cylinder body (2); Insert plate (4), the insert plate (4) is disposed between the outer end face of the cylinder body (2) and an inner arc locking nut (5); There is a gap between the insert plate (4) and the outer end face of the cylinder (2). After the clamping force is established normally, the gap is eliminated, and the insert plate (4) contacts the outer end face of the cylinder (2) but does not transmit force. When the disc spring assembly (3) fails, the micro displacement of the piston rod (1) causes the insert plate (4) to press against the outer end face of the cylinder (2), forming a completely passive rigid force transmission path that is automatically triggered and connected by the displacement of the piston rod (1).

2. The apparatus according to claim 1, characterized in that, The insert plate (4) is a plate-shaped structure with a U-shaped opening, so as to be inserted from the side around the piston rod (1).

3. The apparatus according to claim 1, characterized in that, It also includes an inner arc locking nut (5), which is screwed onto the piston rod (1) and close to the outside of the insert plate (4).

4. The apparatus according to claim 3, characterized in that, Also includes: An outer arc preload nut (6) is screwed onto the outer arc side end of the piston rod (1) to tighten the piston rod (1) to establish a clamping force; An outer arc anti-loosening nut (7) is set close to the outer arc pre-tightening nut (6).

5. The apparatus according to claim 4, characterized in that, Also includes: An outer arc positioning nut (8) is screwed onto the outermost end of the piston rod (1); The outer arc anti-loosening nut 2 (9) is set close to the outer arc positioning nut (8).

6. A method for precisely adjusting the clamping force of a continuous casting crystallizer using the apparatus described in any one of claims 1 to 5, characterized in that, include: Based on the preload of the disc spring assembly, the diameter of the piston rod (1), and the inner diameter of the cylinder (2), the required hydraulic oil pressure in the rod cavity (13) is calculated. According to the calculated hydraulic oil pressure, pressurized oil is introduced into the rod chamber (13) to push the piston rod (1) to compress the disc spring assembly (3); While maintaining the hydraulic oil pressure, insert the insert plate (4) between the outer end face of the cylinder body (2) and the inner arc locking nut (5); Release the hydraulic oil pressure in the rod cavity (13) so that the elastic restoring force of the disc spring assembly (3) is transmitted to the cylinder body (2) through the inner arc locking nut (5) and the insert plate (4), thereby accurately locking the pre-compression state of the disc spring assembly (3).

7. The method according to claim 6, characterized in that, After precisely locking the disc spring assembly (3) into its pre-compression state, a clamping force is established between the inner arc of the wide surface and the outer arc of the wide surface, including: Tighten the outer arc preload nut (6) to pull the piston rod (1) until the gap between the insert plate (4) and the outer end face of the cylinder (2) is eliminated; Tighten the outer arc anti-loosening nut (7) to fix the outer arc preload nut (6); Tighten the outer arc positioning nut (8); Tighten the outer arc anti-loosening nut 2 (9) to lock the outer arc positioning nut (8).

8. The method according to claim 7, characterized in that, Under normal working conditions, the clamping force is provided by the disc spring assembly (3), and the insert plate (4) does not bear the tension. When the disc spring assembly (3) fails unexpectedly, the insert plate (4) contacts the outer end face of the cylinder (2) and rigidly transmits the tension of the piston rod (1) to the cylinder (2) through the inner arc locking nut (5) and the insert plate (4) to provide instantaneous safety protection.

9. The method according to claim 6, characterized in that, The process of calculating the required hydraulic oil pressure in the rod cavity (13) is as follows: Obtain the set disc spring preload value, the piston rod (1) diameter value, and the cylinder body (2) inner diameter value; Calculate the annular effective pressure area of ​​the rod cavity (13); The required hydraulic oil pressure is calculated by dividing the preload value of the set disc spring assembly by the effective pressure area.

10. The method according to claims 6-9, used for precisely adjusting a plurality of clamping points at the upper and lower parts of a crystallizer, characterized in that, The method is applied to each clamping point, and the same calculated hydraulic pressure is used throughout the adjustment of all clamping points.

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