Rolling mill cylinder block repairing method

Abstract

The invention relates to the technical field of rolling mill equipment repairing, and provides a rolling mill cylinder block repairing method which comprises the following steps: systematic decomposition: disassembling a to-be-repaired rolling mill cylinder block into an independent body, a transverse moving part and a roll bending part; digital detection and scheme generation are carried out, three-dimensional scanning and critical dimension measurement are carried out on the disassembled part, measured data are compared with an original design model, and a repair process scheme containing the specific repair target dimension, the material thickening area and the machining path is generated; performing graded repair, performing size and performance recovery on the key functional surface of the cylinder block body by adopting a laser cladding process according to the repair process scheme, and repairing or replacing worn or invalid parts in the transverse moving component and the bending roller component; and integrated assembly and verification are carried out, and all the repaired components are cleaned and assembled. And comprehensive improvement of repairing efficiency, precision and reliability is realized.

Description

Technical Field

[0001] This invention relates to the field of rolling mill equipment repair technology, and more specifically, to a method for repairing rolling mill cylinder blocks. Background Technology

[0002] Rolling mills are core equipment in the metallurgical industry. The key actuators of their roughing and finishing mills are typically driven by large, precision hydraulic cylinder blocks (referred to as cylinder blocks). A cylinder block usually comprises a complex structure including a body, a sliding plate mounted on the body, an internal hydraulic cylinder cavity, a piston rod, guide sleeves, end caps, and various connecting flanges. It is a crucial functional component ensuring the stable operation of the rolling line and the accuracy of the rolled sheet shape. These components are subjected to high pressure, impact loads, and environmental corrosion from high-temperature cooling water and iron oxide scale over long periods. Their critical mating surfaces (such as the sliding plate surface, piston rod mating surface, and sealing surfaces) are prone to wear, corrosion, dimensional deviations, and sealing failures, leading to loss of equipment accuracy, oil leaks, and downtime.

[0003] Currently, the repair of high-value, structurally complex rolling mill cylinder blocks relies heavily on traditional, discrete processes, such as partial welding followed by grinding, manual scraping, or complete replacement. These traditional methods have significant drawbacks: First, the repair process is highly dependent on the operator's personal experience, lacking a systematic and repeatable standard process, leading to large fluctuations and poor consistency in repair quality. Second, there is a lack of precise testing and control methods for restoring critical dimensions and geometric tolerances of the cylinder block (such as the flatness and parallelism of the slide plate surface, and the clearance between the inner bore and the piston rod), making it difficult to ensure that the repaired cylinder block meets the original design precision requirements. Third, traditional methods lack systematic assembly verification and experimental testing processes for the overall performance of the repaired cylinder block, especially the reliability, pressure retention capacity, and long-term operational stability of the hydraulic sealing system. These shortcomings collectively result in low efficiency, high cost, and uncertain service life after repair using traditional repair techniques, failing to meet the maintenance service needs of modern steel enterprises for high reliability, long-term stable operation, and rapid "zero inventory" response for critical equipment. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to provide a systematic, precise, and standardized method for repairing rolling mill cylinder blocks, so as to improve the repair efficiency and accuracy of rolling mill cylinder blocks, extend the service life of cylinder blocks, and reduce costs.

[0005] This invention provides a method for repairing rolling mill cylinder blocks, comprising the following steps: The system is decomposed into an independent body, transverse movement components, and bending roll components; Digital inspection and solution generation involves 3D scanning and key dimension measurement of the disassembled components, comparing the measurement data with the original design model, and generating a repair process solution that includes specific repair target dimensions, material thickening areas, and processing paths. The graded repair is carried out according to the repair process plan. The key functional surfaces of the cylinder block body are restored in size and performance by laser cladding process, and the worn or failed parts in the transverse component and the bending roller component are repaired or replaced. Integrated assembly and verification involves cleaning and assembling all repaired components, and then sequentially performing sealing pressure tests and full-stroke functional verification on the assembled cylinder block assembly.

[0006] Optionally, the systematic decomposition specifically includes: The cleaning process uses a combination of chemical cleaning agent soaking and mechanical polishing to remove oil, oxide scale and rust from the surface of the parts; The hot disassembly process involves locally heating the interference fit or rusted threaded connection parts before disassembly. The component separation process involves separating the transverse sleeve, locking plate, and spacer sleeve from each other in the transverse component. The old parts management process involves counting, labeling, and recording the status of disassembled parts according to their categories.

[0007] Optionally, in the digital detection and solution generation step, The key dimension measurements include the flatness, surface roughness, and total height of the sliding plate surface of the cylinder block body, as well as the inner diameter and roundness of the transverse cylinder and the outer diameter of the piston rod; The repair process specifically specifies the thickness of the laser cladding layer, the cutting depth of machining, and the feed rate.

[0008] Optionally, in the graded repair execution step, the laser cladding of the key functional surfaces adopts a synchronous powder feeding process. During the cladding process, the temperature of the molten pool is monitored by an infrared thermal imager, and the output power of the laser and the moving speed of the scanning head are controlled in a closed loop according to the preset temperature range.

[0009] Optionally, in the graded repair execution step, when performing laser cladding repair on the sliding plate surface of the cylinder block body, for the geometric root area that cannot be effectively covered by the laser beam or whose cladding quality is difficult to guarantee, a mechanical polishing process is used for separate treatment to achieve the specified surface dimensions and quality requirements.

[0010] Optionally, before the laser cladding process is performed, the key functional surfaces are precision milled to ensure that their surfaces meet the preset flatness and roughness requirements. After the laser cladding process is completed, the cladding layer is subjected to stress-relief annealing.

[0011] Optionally, the repair of worn or failed parts in the graded repair execution step includes at least one of the following: The worn surface of the positioning key of the rolling mill cylinder block is laser clad and then ground to the target thickness dimension, which is such that the single-sided gap between the key and the frame after assembly is between 0.05 mm and 0.1 mm. The piston rod of the rolling mill cylinder block is subjected to the following processes in sequence: removal of the old chromium layer, grinding and correction of the substrate, re-plating of hard chromium, and finally precision grinding to the dimensions shown in the drawing. The inner hole of the guide copper sleeve of the rolling mill cylinder block is bored, and a wear-resistant and lubricating coating is prepared on its surface by thermal spraying. The worn sealing surface of the end cover of the rolling mill cylinder block is welded with copper alloy and then machined to the specified dimensions and dimensional tolerances. The modification of the oil inlet flange of the rolling mill cylinder block includes enlarging the diameter of the original connecting hole, replacing it with a larger diameter connecting bolt, and replacing the hydraulic pipe joint with a standard joint with a higher rated pressure.

[0012] Optionally, the sealing pressure test in the integrated assembly and verification step is carried out by gradually increasing the pressure from low pressure to high pressure and holding it at 28MPa for 30 minutes; the full-stroke functional action verification requires the transverse component and the bending roller component to continuously complete at least five full-stroke reciprocating movements without jamming under the test pressure.

[0013] Optionally, after the integrated assembly and verification steps, the method further includes: performing painting and data archiving, spraying anti-rust paint on the verified cylinder block assembly, and associating and storing the scan data, process parameters, inspection records and test reports involved in this repair with the unique identification code of the cylinder block assembly.

[0014] Optionally, the method is used to repair the balance block of a hot rolling roughing mill and / or the continuously variable crown control block of a hot rolling finishing mill; when the repair object is a combined continuously variable crown control block, the systematic decomposition step includes separating it into independent individual components, and the graded repair execution step includes repairing each individual component separately and then performing combined processing to ensure overall accuracy.

[0015] Compared with related technologies, the rolling mill cylinder block repair method provided by the present invention has the following technical advantages: The rolling mill cylinder block repair method provided by this invention scientifically decomposes the cylinder block to be repaired into independent functional modules through a "systematic decomposition" step, creating a clear and orderly working interface for subsequent precision repair. This allows the repair work to be carried out modularly and in parallel, avoiding the chaos and inefficiency of traditional holistic processing. Then, through the "digital detection and scheme generation" step, 3D scanning and digital model comparison are used to transform vague judgments based on personal experience into precise repair blueprints based on data. This quantifies the repair objectives and solidifies the process path, fundamentally overcoming the drawbacks of unstable quality in traditional methods. On this basis, the "tiered repair execution" step, based on the above-mentioned digital scheme, uses advanced laser melting on the core cylinder block body. The process involves restoring performance through a plating process, and selectively repairing or replacing auxiliary components as needed. This allows for the precise allocation of valuable repair resources, effectively controlling costs while ensuring overall repair quality. Finally, through the "integrated assembly and verification" steps, all repaired parts undergo systematic cleaning, assembly, and rigorous operational simulation testing. This ensures that the repaired cylinder block assembly fully meets or even exceeds the original design standards in terms of sealing reliability, operational smoothness, and overall performance. This forms a complete quality closed loop from disassembly, testing, repair to verification, ultimately comprehensively solving the industry problems of large fluctuations in repair quality, difficulty in guaranteeing accuracy, and lack of systematic verification in traditional methods. This achieves a comprehensive improvement in repair efficiency, accuracy, and reliability. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of the mill cylinder block repair method according to an embodiment of the present invention. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein.

[0019] In the description of this invention, the orientations or positional relationships indicated by terms such as "up," "down," "left," "right," "top," "bottom," "front," "back," "inner," and "outer" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing this invention. They are not intended to indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this invention.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] In the description of this specification, references to terms such as "embodiment," "one embodiment," and "one implementation" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or implementation is included in at least one embodiment or illustrative implementation of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or implementations.

[0022] like Figure 1 As shown, this embodiment of the invention provides a method for repairing rolling mill cylinder blocks, including the following steps: Step S1: Systematic decomposition, disassembling the mill cylinder block to be repaired into independent main body, transverse movement component and bending roll component; Step S2, Digital Inspection and Solution Generation: Perform 3D scanning and key dimension measurement on the disassembled components, compare the measurement data with the original design model, and generate a repair process solution that includes specific repair target dimensions, material thickening areas, and processing paths. Step S3: Graded repair is performed. According to the repair process plan, the key functional surfaces of the cylinder block body are restored in size and performance using laser cladding process, and worn or failed parts in the transverse component and the bending roller component are repaired or replaced. Step S4, Integrated Assembly and Verification: Clean and assemble all repaired parts, and sequentially perform sealing pressure tests and full-stroke functional action verifications on the assembled cylinder block assembly.

[0023] It should be noted that traditional rolling mill cylinder block repair methods, when dealing with high-value, structurally complex components, generally suffer from problems such as reliance on operator experience and a lack of systematic and standardized processes. This leads to significant fluctuations and inconsistencies in repair quality. Furthermore, existing technologies lack precise detection and control methods for restoring critical dimensions and geometric tolerances of the cylinder block, making it difficult to ensure that the repaired cylinder block meets the original design accuracy requirements. Traditional methods also lack systematic assembly verification and experimental testing processes for the overall performance of the repaired cylinder block, particularly the reliability and long-term operational stability of the hydraulic sealing system, resulting in low repair efficiency, high costs, and uncertain service life.

[0024] For ease of understanding, the following explains some key terms in this embodiment: A rolling mill cylinder block is a large hydraulic actuator used in rolling mill equipment to drive the rolls or perform other key actions. Its internal structure is complex and contains multiple cooperating components.

[0025] The main body refers to the main structure of the rolling mill cylinder block, which usually bears the main hydraulic chambers and key functional surfaces, and is the core support of the entire cylinder block.

[0026] The lateral movement component refers to the functional unit in the rolling mill cylinder block responsible for realizing the lateral movement of the rolls or related mechanisms. Its motion accuracy affects the stability of the rolling process.

[0027] The bending roll component refers to the functional unit in the rolling mill cylinder block used to adjust the bending degree of the roll to control the shape of the plate. Its performance directly affects the product quality.

[0028] 3D scanning refers to the method of acquiring three-dimensional geometric data of an object's surface through optical, laser, or other non-contact technologies, which is used to create high-precision digital models.

[0029] Critical dimension measurement refers to the precise measurement of geometric parameters in rolling mill cylinder blocks and their components that have a decisive influence on function, fit accuracy, and performance.

[0030] A repair process plan is a detailed technical guidance document developed based on test data and original design requirements for the repair of rolling mill cylinder blocks. It includes repair objectives, material selection, processing paths, and other related information.

[0031] Laser cladding is an advanced manufacturing technology that uses a high-energy laser beam to melt metal powder and metallurgically bond it to the surface of a substrate to form a high-performance cladding layer, thereby restoring or improving the surface dimensions and performance of components.

[0032] Sealing pressure test refers to hydraulically pressurizing the repaired rolling mill cylinder block assembly to verify the sealing performance and pressure holding capability of its internal hydraulic system.

[0033] Full-stroke functional motion verification refers to driving the repaired mill cylinder block assembly to complete its full-stroke reciprocating motion as specified in its design under test conditions, in order to evaluate the smoothness, stability and functional integrity of its mechanical motion.

[0034] The mill cylinder block repair method in this embodiment can be implemented as follows: In the systematic disassembly process, the mill cylinder block to be repaired is transported to a dedicated disassembly area. Operators can use conventional mechanical tools, such as wrenches, screwdrivers, and hydraulic jacks, to disassemble the cylinder block step by step according to a pre-defined general disassembly procedure. During disassembly, the main focus is on physically separating the cylinder block's main structure (body), the components responsible for lateral movement (lateral movement components), and the components responsible for adjusting roll bending (bending roll components). For example, these key functional modules can be separated from the overall cylinder block by removing fasteners such as connecting bolts and pins, facilitating subsequent independent inspection and repair.

[0035] In the digital inspection and solution generation process, firstly, the separated main body, transverse components, and bending roll components are placed on an inspection platform. Non-contact 3D scanning equipment, such as scanners based on structured light or laser triangulation, can be used to collect data on the surface geometry of each component, generating high-density point cloud data. Simultaneously, common measuring tools, such as vernier calipers, micrometers, depth gauges, and inside diameter gauges, can be used to manually measure important mating and installation dimensions of the components. Secondly, the collected 3D scanning data and manual measurement data are imported into computer-aided design (CAD) software or specialized reverse engineering software. This data can be overlaid or compared with the original design 3D model of the rolling mill cylinder block for this model. Software tools can identify areas of wear, deformation, and corrosion on the component surface and quantify their deviations from the original design. Based on the above comparative analysis results, technicians can develop detailed repair process plans. The plan can be presented in the form of an electronic document or a paper document, which clearly specifies the target dimensions of each area to be repaired, the specific areas where material thickening is required by means such as welding, spraying, etc., and the rough path and machining allowance for subsequent machining (such as turning, milling, grinding). For example, for a worn skateboard surface, the plan can indicate the final flatness requirements and the area where material buildup is required.

[0036] In the graded repair execution step, based on the aforementioned repair process plan, laser cladding is implemented on key functional surfaces of the cylinder block body that require dimensional and performance restoration, such as sliding plate surfaces and guide surfaces. A laser cladding device equipped with a laser, powder feeder, and motion control system can be used. Operators, according to the parameters set in the plan, deliver suitable metal powder to the laser focal area via the powder feeder. The laser beam melts and rapidly solidifies the powder and substrate surface, forming a new metallurgical bonding layer. By controlling basic parameters such as laser power, scanning speed, and powder feed rate, the cladding layer can be deposited, thereby restoring the original dimensions of the component. Simultaneously, worn or failed parts detected in the transverse and bending roller components, such as bushings, seals, and connecting pins, can be processed according to their degree of damage and the repair process plan. For slightly worn parts, conventional machining methods, such as turning and grinding, can be used to remove the worn layer and restore dimensions. For severely worn or unrepairable parts, they are directly replaced with new parts that meet the original design requirements. For example, worn guide sleeves can be boring or replaced with new ones.

[0037] In the integrated assembly and verification process, all repaired or replaced components must undergo thorough cleaning before assembly to remove impurities such as chips, oil, and dust generated during processing. After cleaning, operators assemble the main body, traverse components, bending roll components, and other auxiliary parts into a complete mill cylinder assembly according to assembly drawings and general assembly specifications. During assembly, tools such as torque wrenches are used to ensure that the connection torque of fasteners meets requirements and to check the clearance of each mating surface. Subsequently, the assembled mill cylinder assembly is connected to a hydraulic test bench. First, a sealing pressure test is performed by injecting hydraulic oil into the cylinder block using a hydraulic pump and gradually increasing the pressure, observing for any leakage, and recording the pressure holding time. Next, a full-stroke functional action verification is performed by controlling the hydraulic system to drive the piston rod or related actuators of the cylinder block, enabling it to complete the reciprocating motion from the starting position to the ending position under no-load or light-load conditions. During this process, the smoothness of the movement and the absence of jamming, abnormal noises, or other abnormalities are observed.

[0038] In this embodiment, the mill cylinder block repair method provides a "systematic decomposition" step, which scientifically breaks down the cylinder block to be repaired into independent functional modules. This creates a clear and orderly working interface for subsequent precision repair, enabling the repair work to be carried out modularly and in parallel, avoiding the chaos and inefficiency of traditional holistic processing. Then, through the "digital detection and solution generation" step, 3D scanning and digital model comparison are used to transform the fuzzy judgment based on personal experience into a data-driven, precise repair blueprint. This quantifies the repair target and solidifies the process path, fundamentally overcoming the drawbacks of unstable quality in traditional methods. Based on this, the "tiered repair execution" step, according to the above-mentioned digital solution, uses advanced technology to repair the core cylinder block body. The laser cladding process restores performance, while selectively repairing or replacing auxiliary components as needed. This allows for precise allocation of valuable repair resources, effectively controlling costs while ensuring overall repair quality. Finally, through the "integrated assembly and verification" step, all repaired parts undergo systematic cleaning, assembly, and rigorous operating condition simulation testing. This ensures that the repaired cylinder assembly fully meets or even exceeds the original design standards in terms of sealing reliability, operational stability, and overall performance. This forms a complete quality closed loop from disassembly, testing, repair to verification, ultimately comprehensively solving the industry problems of large quality fluctuations, difficulty in guaranteeing accuracy, and lack of systematic verification in traditional methods. This achieves a comprehensive improvement in repair efficiency, accuracy, and reliability.

[0039] Optionally, the systematic decomposition specifically includes: The cleaning process uses a combination of chemical cleaning agent soaking and mechanical polishing to remove oil, oxide scale and rust from the surface of the parts; The hot disassembly process involves locally heating the interference fit or rusted threaded connection parts before disassembly. The component separation process involves separating the transverse sleeve, locking plate, and spacer sleeve from each other in the transverse component. The old parts management process involves counting, labeling, and recording the status of disassembled parts according to their categories.

[0040] Specifically, the cleaning process aims to thoroughly remove various contaminants from the surface of components, providing a clean foundation for subsequent inspection and repair work. This process can be implemented in various ways. For example, suitable industrial cleaning agents (such as alkaline degreasers and acidic rust removers) can be used to soak the components, utilizing chemical reactions to dissolve oil, oxides, and rust. The soaking time, temperature, and cleaning agent concentration can be adjusted according to the type and severity of the contaminants. Alternatively, mechanical means such as grinding wheels, wire brushes, and abrasive blasting (such as sandblasting and shot blasting) can be used to physically remove strongly adhering oil, scale, and rust layers. Different abrasives and grinding intensities can be selected according to the component material and surface requirements. In addition, for components with complex shapes or many internal channels, ultrasonic cleaning can be used, utilizing the cavitation effect generated by ultrasound in the cleaning solution to efficiently remove fine dirt.

[0041] The thermal disassembly process utilizes the principle of thermal expansion and contraction. By locally heating the interference fit or corroded threaded connection, it expands or softens the connection, thereby reducing the force required for disassembly and effectively preventing damage to components during the disassembly process. This process can be implemented in ways including, but not limited to: using induction heating equipment to locally and rapidly heat the threaded connection, causing it to expand and loosen the connection; or using an acetylene-oxygen flame or propane flame to locally heat the connection, but temperature control is necessary to avoid material degradation; or inserting an electric heating rod for internal heating of specific holes or bolts.

[0042] The component separation process involves the precise disassembly of key components in the lateral movement assembly, such as the lateral sleeve, locking plate, and spacer sleeve, ensuring that each component can be processed independently for subsequent detailed inspection and repair. In practice, specialized tooling fixtures and disassembly tools that match the structure of these components can be designed or used to ensure a smooth and damage-free disassembly process. For tightly fitted components, hydraulic ejection or pulling devices can be used to assist separation by applying uniform and controllable force. Before separation, the components are usually marked to record their relative positions and orientations for correct reassembly later.

[0043] The aforementioned used parts management process aims to systematically classify, label, and record the status of disassembled parts to achieve traceable management of part status, prevent confusion or misuse, and provide accurate basis for subsequent repair or replacement. This process can be implemented in several ways: classifying parts according to type (e.g., bolts, gaskets, seals, structural components), material, degree of wear, etc., and placing them in clearly labeled dedicated storage containers or areas; or, using barcodes, QR codes, or RFID tags to uniquely identify each part, and recording its original status, disassembly date, cylinder block number, inspection results, etc., through a computer system; while recording the status, the system can also simultaneously assess whether the part is repairable, needs replacement, or should be scrapped, and proceed with further processing based on the assessment results.

[0044] In this embodiment, through the detailed cleaning, thermal disassembly, component separation, and used parts management processes described above, this application ensures that during the systematic disassembly process, surface contaminants on the rolling mill cylinder block can be thoroughly removed, interference fits or corroded parts can be safely disassembled, key components are precisely separated, and all disassembled parts are systematically managed. This series of meticulous disassembly steps fundamentally solves the problems of incomplete removal of surface contaminants, difficulty in disassembly, and chaotic parts management. Therefore, it provides clean, non-destructive, and traceable components for subsequent digital inspection and solution generation, significantly improving the accuracy of inspection and the reliability of repair solution development, avoiding secondary damage or information loss caused by improper disassembly, thereby making the entire rolling mill cylinder block repair process more efficient, accurate, and reliable, laying a solid foundation for the final high-quality repair of the cylinder block.

[0045] Optionally, in the digital detection and solution generation step, The key dimension measurements include the flatness, surface roughness, and total height of the sliding plate surface of the cylinder block body, as well as the inner diameter and roundness of the transverse cylinder and the outer diameter of the piston rod; The repair process specifically specifies the thickness of the laser cladding layer, the cutting depth of machining, and the feed rate.

[0046] Specifically, in the key dimension measurement, the flatness of the sliding plate surface of the cylinder block body is measured. Flatness refers to the smoothness of an object's surface relative to an ideal plane. This can be measured by scanning the sliding plate surface at multiple points using a laser tracker, fitting the actual plane using software, and calculating the maximum deviation between each point and the fitted plane. Alternatively, a coordinate measuring machine (CMM) equipped with a contact or non-contact probe can be used to perform grid sampling on the sliding plate surface to obtain its three-dimensional coordinate data, thereby analyzing the flatness error. The surface roughness of the sliding plate surface is also measured. Surface roughness is a parameter describing the microscopic geometric characteristics of an object's surface, reflecting the surface's microscopic unevenness. This can be measured by a stylus-type roughness meter, where a diamond stylus slides across the surface, recording vertical displacement changes to calculate the roughness parameter. Alternatively, an optical roughness meter can be used, employing optical interference or confocal principles to non-contactly acquire surface morphology data and calculate roughness. The total height dimension of the slide plate surface is measured. The total height dimension refers to the overall height of the cylinder block body in a specific direction. It can be measured at multiple locations using a high-precision digital height gauge and the average value is taken, or a coordinate measuring machine can be used to measure the reference surface and the top functional surface of the cylinder block body and calculate the vertical distance between them.

[0047] In addition, the key dimension measurements also include measuring the inner diameter of the transverse cylinder, which refers to the diameter of the cylindrical hole inside the transverse cylinder. This can be measured using an inside micrometer at multiple points at different depths and angles to obtain the average diameter and the maximum / minimum diameter, or using a coordinate measuring machine (CMM) to obtain point cloud data by scanning the inner hole wall, then fitting a cylinder and calculating its diameter. The roundness of the transverse cylinder is also measured. Roundness describes how close the cross-section of a cylindrical or conical surface is to an ideal circle. This can be measured using a roundness meter by rotating the workpiece or probe and recording radial runout to assess roundness error, or using a CMM by collecting multiple points on the inner hole cross-section, fitting the optimal circle, and calculating its deviation from the actual contour. Finally, the outer diameter of the piston rod is measured. The outer diameter refers to the diameter of the cylindrical surface outside the piston rod. This can be measured using an outside micrometer at multiple points in different axial and radial directions on the piston rod, or using a laser diameter gauge to measure the diameter change of the piston rod in real time during rotation or movement in a non-contact manner.

[0048] Meanwhile, the repair process specifically specifies the thickness of the laser cladding layer. This thickness refers to the vertical dimension of the cladding layer formed on the substrate surface by the laser cladding process. The specified thickness is typically determined based on the wear depth calculated from 3D scanning data, combined with the shrinkage rate of the cladding material and subsequent machining allowance, to precisely set the target thickness of the cladding layer. Alternatively, a stable thickness range of the cladding layer under different laser process parameters can be determined through pre-experiments and incorporated into the process plan. The repair process also specifically specifies the cutting depth during machining. The cutting depth refers to the depth to which the tool penetrates the workpiece material each time during machining. The specified cutting depth is typically set for roughing and finishing based on the cladding layer thickness. Roughing involves a larger cutting depth to quickly remove material, while finishing involves a smaller cutting depth to ensure dimensional accuracy and surface quality. Alternatively, the cutting depth can be optimized based on the material hardness and tool type to avoid machining deformation or tool wear. The repair process further specifies the feed rate for machining. The feed rate refers to the distance that the tool or workpiece moves along the feed direction during each cut or each revolution in the machining process. Generally, a larger feed rate is used in the roughing stage to improve machining efficiency, while a smaller feed rate is used in the finishing stage to obtain higher surface finish and dimensional accuracy. Alternatively, the appropriate feed rate can be determined by consulting machining manuals or empirical formulas based on the machine tool's performance parameters and machining requirements.

[0049] In this embodiment, through the aforementioned technical solution, the measurement of key dimensions in the digital detection and solution generation steps is comprehensively and specifically defined. This includes not only key functional parameters such as the flatness, surface roughness, and overall height of the cylinder block's sliding surface, but also dimensions of easily worn mating components such as the inner diameter and roundness of the transverse cylinder and the outer diameter of the piston rod. This comprehensive measurement ensures accurate understanding of the wear and deformation of key parts of the rolling mill cylinder block, avoiding repair blind spots or insufficient accuracy due to inadequate measurement. Simultaneously, the repair process scheme further specifies core process parameters such as the thickness of the laser cladding layer and the cutting depth and feed rate during machining, providing clear and controllable guidance for material thickening, excess material removal, and final dimensional shaping during the repair process. This significantly improves the operability and repeatability of the repair process, effectively solving the problem of insufficient repair accuracy caused by incomplete measurement and unclear parameters in traditional methods. Through precise dimensional data and clear process parameter guidance, it can be ensured that the repaired rolling mill cylinder block meets or even exceeds the original design accuracy requirements, thereby extending its service life and improving the stability and reliability of equipment operation.

[0050] Optionally, in the graded repair execution step, the laser cladding of the key functional surfaces adopts a synchronous powder feeding process. During the cladding process, the temperature of the molten pool is monitored by an infrared thermal imager, and the output power of the laser and the moving speed of the scanning head are controlled in a closed loop according to the preset temperature range.

[0051] Specifically, the synchronous powder feeding process refers to the process where, during laser cladding, the powder material is coaxially or synchronously fed into the molten pool region with the laser beam at a specific angle. For example, a coaxial powder feeding nozzle can be used to heat and melt the powder particles in the central region of the laser beam, thereby forming a uniform molten pool; alternatively, multiple lateral powder feeding nozzles can be used to symmetrically feed the powder into the laser-acting area, ensuring uniform powder distribution. This process enables precise matching of powder and laser energy, reduces powder splashing and material waste, and helps to form a dense and uniform cladding layer.

[0052] Monitoring the molten pool temperature using an infrared thermal imager during the cladding process refers to real-time, non-contact temperature measurement of the molten pool formed during laser cladding. For example, a high-resolution infrared thermal imager can be used to capture the infrared radiation emitted by the molten pool and convert it into a visualized temperature distribution map, thereby accurately obtaining the instantaneous temperature information of the molten pool. Alternatively, an infrared temperature measurement module integrated into the laser head can be used to perform point- or line-based temperature monitoring of specific areas of the molten pool. This monitoring method can promptly detect abnormal fluctuations in the molten pool temperature, providing accurate data support for subsequent closed-loop control.

[0053] The closed-loop control of the laser's output power and the scanning head's moving speed based on a preset temperature range refers to adjusting the laser's output power and the scanning head's moving speed in real time, based on the molten pool temperature data monitored by the infrared thermal imager, to maintain the molten pool temperature within a preset ideal range. For example, when the molten pool temperature is detected to be higher than the preset upper limit, the control system can reduce the laser's output power or increase the scanning head's moving speed to reduce heat input; conversely, when the molten pool temperature is lower than the preset lower limit, the laser's output power can be increased or the scanning head's moving speed reduced to increase heat input. This closed-loop control mechanism can be implemented using a PID (proportional-integral-derivative) controller, a fuzzy logic controller, or an adaptive control algorithm to ensure the stability of the cladding process and effectively suppress temperature fluctuations.

[0054] In this embodiment, by employing the aforementioned technical solution, a synchronous powder feeding process is used during laser cladding repair of the key functional surfaces of the rolling mill cylinder block. This ensures the precise and uniform feeding of powder materials, improving material utilization and promoting the uniformity of the cladding layer quality. Simultaneously, real-time monitoring of the molten pool temperature using an infrared thermal imager accurately captures changes in the thermal field during the cladding process, allowing for the timely detection of potential temperature anomalies. Furthermore, closed-loop control of the laser's output power and the scanning head's movement speed, combined with a preset temperature range, precisely maintains the molten pool temperature within the optimal process window. This effectively avoids defects such as molten pool splashing, porosity, and cracks caused by excessively high temperatures, as well as poor fusion due to excessively low temperatures. This significantly improves the density, bonding strength, and dimensional accuracy of the cladding layer, ensuring that the repaired key functional surfaces of the cylinder block meet the original design requirements. Moreover, combined with the specific regulations regarding laser cladding layer thickness, machining depth of cut, and feed rate in the aforementioned repair process, it further guarantees the refinement and controllability of the repair process, thereby improving the repair quality and reliability of the rolling mill cylinder block and extending its service life.

[0055] Optionally, in the graded repair execution step, when performing laser cladding repair on the sliding plate surface of the cylinder block body, for the geometric root area that cannot be effectively covered by the laser beam or whose cladding quality is difficult to guarantee, a mechanical polishing process is used for separate treatment to achieve the specified surface dimensions and quality requirements.

[0056] Specifically, the geometric root region typically refers to the right-angle interior angle where the slide surface meets the side surface. Due to laser head interference or beam angle issues, the cladding layer at this location may be uneven. In this case, a handheld angle grinder with a louvered grinding wheel can be used to perform localized fine polishing on this area, ensuring a smooth transition with the surrounding already clad and repaired areas, and jointly meeting the dimensional tolerances and surface roughness requirements specified in the drawings.

[0057] In this embodiment, by addressing and specifically treating the blind spots in the laser cladding process, areas that might have been quality bottlenecks due to technical limitations are effectively supplemented and processed. Furthermore, through a combined process of "laser cladding as the main method and local polishing as a supplementary method," the entire functional surface of the slide plate, regardless of its geometric complexity, can achieve complete and consistent repair quality. This results in full coverage and high reliability of the repair effect, demonstrating the flexibility and thoroughness of the method in solving practical engineering problems.

[0058] Optionally, before the laser cladding process is performed, the key functional surfaces are precision milled to ensure that their surfaces meet the preset flatness and roughness requirements. After the laser cladding process is completed, the cladding layer is subjected to stress-relief annealing.

[0059] Specifically, the key functional surfaces are precision milled to achieve preset flatness and roughness requirements. This precision milling aims to provide a high-quality substrate surface for subsequent laser cladding. Specifically, precision milling can be achieved using a CNC milling machine, utilizing high-precision tools and optimized cutting parameters to control the surface flatness of the key functional surfaces at the micrometer level and achieve specific surface roughness requirements. In addition to precision milling, precision grinding, lapping, or polishing can also be used to achieve similar surface quality requirements, ensuring that the surface is free of obvious defects, oil stains, or oxide layers before cladding, thereby providing a good adhesion base for the cladding layer.

[0060] Stress-relief annealing is performed on the cladding layer to eliminate or significantly reduce residual thermal stress generated during the rapid heating and cooling process of laser cladding. Specifically, stress-relief annealing typically involves heating the clad part to a specific temperature below its phase transformation point (e.g., between 400°C and 650°C for steel), holding it at this temperature for a period of time (e.g., 2 to 4 hours), followed by slow cooling. This process can be carried out in a resistance furnace, gas furnace, or induction heating equipment. In addition to traditional furnace annealing, methods such as local induction heating, vibration aging, or laser shock annealing can also be used to reduce residual stress and prevent cracking of the cladding layer, deformation of the part, or premature failure during long-term use.

[0061] In this embodiment, by performing precision milling on the key functional surfaces before the laser cladding process, uneven, rough, or defective areas can be effectively removed, providing a uniform, flat substrate with good roughness for laser cladding. This significantly improves the bonding strength between the cladding layer and the substrate, avoiding defects such as poor adhesion, uneven thickness, or internal porosity caused by poor surface conditions, thereby improving the density and uniformity of the cladding layer. Simultaneously, stress-relief annealing of the cladding layer after the laser cladding process effectively releases residual thermal stress generated by rapid local heating and cooling during cladding. This fundamentally solves the problems of cladding layer cracking, component deformation, and premature failure during long-term service, ensuring that the repaired mill cylinder block has higher structural integrity, dimensional stability, and a longer service life. This solution, through process optimization before and after laser cladding, significantly improves the repair quality and reliability of the key functional surfaces of the mill cylinder block, enabling it to better meet the requirements of high reliability and long-term stable operation of rolling mill equipment.

[0062] Optionally, the repair of worn or failed parts in the graded repair execution step includes at least one of the following: The worn surface of the positioning key of the rolling mill cylinder block is laser clad and then ground to the target thickness dimension, which is such that the single-sided gap between the key and the frame after assembly is between 0.05 mm and 0.1 mm. The piston rod of the rolling mill cylinder block is subjected to the following processes in sequence: removal of the old chromium layer, grinding and correction of the substrate, re-plating of hard chromium, and finally precision grinding to the dimensions shown in the drawing. The inner hole of the guide copper sleeve of the rolling mill cylinder block is bored, and a wear-resistant and lubricating coating is prepared on its surface by thermal spraying. The worn sealing surface of the end cover of the rolling mill cylinder block is welded with copper alloy and then machined to the specified dimensions and dimensional tolerances. The modification of the oil inlet flange of the rolling mill cylinder block includes enlarging the diameter of the original connecting hole, replacing it with a larger diameter connecting bolt, and replacing the hydraulic pipe joint with a standard joint with a higher rated pressure.

[0063] Specifically, the locating key of the rolling mill cylinder block primarily functions to ensure precise alignment and fixation between the cylinder block and the mill stand. Wear on the locating key's surface can lead to excessive clearance, affecting positioning accuracy and operational stability. Therefore, this application employs laser cladding technology to repair the worn surface. Laser cladding is an advanced surface modification technology that uses a high-energy laser beam to melt alloy powder and metallurgically bond it to the substrate, forming a dense, high-hardness, and highly wear-resistant cladding layer, thereby restoring the original dimensions and surface properties of the locating key. For example, nickel-based or cobalt-based alloy powders can be used for cladding to enhance the wear resistance after repair. After cladding, excess material is removed by precision grinding, precisely controlling the locating key's thickness to the target size. This target size is designed to ensure that the single-sided clearance after assembly with the mill stand is precisely between 0.05 mm and 0.1 mm, thus restoring its accurate positioning function. In addition to laser cladding, other welding processes such as arc welding or plasma welding can be used to form a thickened layer on the worn surface. This layer is then processed by a CNC grinding machine or a precision milling machine, and combined with an online measurement system to monitor the grinding amount in real time, ensuring that the final thickness meets the preset gap requirements.

[0064] For the piston rod of a rolling mill cylinder block, as a key moving component of the hydraulic cylinder, the hard chromium layer on its surface is crucial for wear resistance and corrosion resistance. When the old chromium layer fails or the substrate wears, it severely affects sealing performance and motion accuracy. This application proposes a systematic repair process: First, a process to remove the old chromium layer is performed, which can be done using chemical stripping methods (such as electrolytic stripping) or mechanical stripping methods (such as belt grinding) to thoroughly remove the old hard chromium layer and ensure a clean substrate surface. Second, a grinding and substrate correction process is performed, using an external cylindrical grinder to grind the piston rod substrate to correct dimensional deviations and form and position errors caused by wear, corrosion, or peeling of the old chromium layer, providing a qualified substrate surface for subsequent chromium plating. Third, a new hard chromium plating process is performed, using an electroplating hard chromium process to deposit a new, uniform, and dense hard chromium layer on the piston rod substrate surface, typically with a thickness between 0.05 mm and 0.2 mm, to provide excellent wear resistance and corrosion resistance. Finally, a final precision grinding process is performed. After chrome plating, the hard chrome layer is precision ground using a high-precision cylindrical grinder to achieve the final dimensions, surface roughness, and roundness requirements specified in the drawings. Besides electroplating hard chrome, thermal spraying technologies such as high-speed arc spraying (HVOF) or plasma spraying (APS) can also be considered to prepare a ceramic or cermet coating on the modified substrate to provide higher hardness and wear resistance, followed by precision grinding.

[0065] For the guide copper sleeve of the rolling mill cylinder block, wear of its inner bore can lead to unstable piston rod movement and seal failure. The repair solution proposed in this application includes boring the inner bore of the guide copper sleeve to remove the wear layer and correct dimensional errors such as roundness and cylindricity to achieve the required dimensional accuracy. After boring, a wear-resistant and lubricating coating is prepared on its surface using a thermal spraying process. Thermal spraying technologies, such as high-speed arc spraying (HVOF) or plasma spraying (APS), can form a coating with excellent wear resistance and lubrication properties on the inner bore surface. The coating material can be a nickel-based self-fluxing alloy, a hard alloy such as tungsten carbide-cobalt, or a polytetrafluoroethylene (PTFE) composite coating to provide a low coefficient of friction and high wear resistance. In addition to thermal spraying, chemical nickel-phosphorus (Ni-P) plating or composite electroplating (such as Ni-PTFE) can also be used after boring to form a coating with self-lubricating and wear-resistant properties on the inner bore surface.

[0066] For the end caps of rolling mill cylinder blocks, their sealing surfaces are critical components for hydraulic cylinder sealing, and wear can lead to leakage. This application employs copper alloy surfacing technology to repair worn sealing surfaces. Copper alloy surfacing, for example through processes such as TIG welding, MIG welding, or oxyacetylene welding, deposits a layer of copper alloy material (such as tin bronze or aluminum bronze) onto the worn sealing surface of the end cap. Copper alloys have good corrosion resistance and machinability, and exhibit good fit with the sealing components. After surfacing, excess material is removed by machining, and the surfacing layer is precisely machined to meet the dimensional accuracy, surface roughness, and geometric tolerances (such as flatness and perpendicularity) specified in the drawings, ensuring a good fit with the sealing components and effectively preventing hydraulic leakage. In addition to copper alloy surfacing, stainless steel or nickel-based alloys can also be selected for surfacing depending on the specific operating conditions and sealing requirements. Laser cladding can also be used as the surfacing process to obtain a finer microstructure and less thermal deformation.

[0067] For the oil inlet flange of the rolling mill cylinder block, the modification aims to improve the strength and pressure resistance of the hydraulic connection to adapt to higher workloads or address the problem of insufficient strength in the original connection. The modification scheme includes enlarging the diameter of the original mating hole, for example, by using a drilling machine or boring machine to enlarge the original mating hole on the flange to accommodate larger diameter connecting bolts. Subsequently, larger diameter connecting bolts are used, selecting bolts with higher strength grades and larger diameters to provide greater preload and shear strength, enhancing the reliability of the flange connection. Simultaneously, the hydraulic pipe fittings are replaced with standard fittings with higher rated pressures to ensure the pressure resistance of the entire hydraulic circuit is matched, for example, by replacing them with fittings that meet higher rated pressure standards (such as ISO 6162-1 / 2 or SAE J518). Besides simply enlarging the hole diameter and replacing the bolts, reinforcing ribs or gaskets can also be added to the back of the flange to enhance local strength. For hydraulic pipe fittings, in addition to replacing standard fittings, welded or compression fitting connections can be considered to further improve sealing and pressure resistance.

[0068] In this embodiment, through the aforementioned technical solution, a customized and standardized repair process is provided for different types of worn or failed parts in the rolling mill cylinder block, thereby solving the problems of inconsistent repairs and insufficient precision in traditional methods. This tiered and refined repair strategy ensures that the repair of each key component meets or exceeds the original design requirements, significantly improving the consistency and reliability of repair quality, extending the service life of the repaired cylinder block, and reducing the risk of secondary failures due to improper repair. The standardized process reduces reliance on the operator's personal experience, improves repair efficiency, and ensures that the repaired rolling mill cylinder block meets the needs of modern steel enterprises for high reliability and long-term stable operation of key equipment.

[0069] Optionally, the sealing pressure test in the integrated assembly and verification step is carried out by gradually increasing the pressure from low pressure to high pressure and holding it at 28MPa for 30 minutes; the full-stroke functional action verification requires the transverse component and the bending roller component to continuously complete at least five full-stroke reciprocating movements without jamming under the test pressure.

[0070] Specifically, the sealing pressure test employs a staged pressure increase method from low to high pressure, aiming to gradually apply pressure to test the sealing performance of the hydraulic system at different pressure levels. Its main purpose is to avoid instantaneous damage to seals with minor defects that could be caused by directly applying high pressure, while allowing initial leaks to be detected and corrected at lower pressure stages, thereby improving the safety, accuracy, and repair efficiency of the test. This can be achieved using a hydraulic pump station in conjunction with multiple pressure sensors and control valves. A low initial pressure value (e.g., 5 MPa) is first set, and after holding the pressure for a period, the pressure is gradually increased to the next preset value (e.g., 10 MPa, 15 MPa, etc.) until the final test pressure is reached. The pressure increase and holding time for each stage can be adjusted according to the cylinder size, structural complexity, and seal type. Alternatively, an automated test bench can be used, with programmed control of proportional or servo valves to achieve a smooth, linear, or stepped pressure increase. The test system can monitor the pressure change rate and leakage in real time; once an abnormality is detected, pressure increase is immediately stopped and an alarm is triggered for troubleshooting.

[0071] The sealing pressure test is conducted by holding the pressure at 28 MPa for 30 minutes. 28 MPa is a common rated working pressure or peak pressure in rolling mill hydraulic systems. Holding this pressure for 30 minutes simulates the sealing reliability of the cylinder block under actual high-load conditions for extended periods. This prolonged high-pressure holding fully exposes the creep, fatigue, and minute leakage channels of the seal, ensuring that the repaired cylinder block will not cause downtime due to seal failure in actual production. In practice, after phased pressurization, the system pressure is stabilized at 28 MPa, and a timer is started. During this period, the system pressure is continuously monitored using a high-precision pressure sensor, combined with a flow meter or level sensor to monitor changes in the tank level to quantify leakage. If the pressure drop rate or level change exceeds a preset threshold, the seal is deemed unqualified. Alternatively, a hydraulic test bench with data logging capabilities can be used to hold the pressure at 28 MPa. During the test, in addition to monitoring pressure and level, an infrared thermal imager can be used to detect temperature changes in the sealing area, or an ultrasonic leak detector can be used to assist in locating potential leak points, providing more comprehensive diagnostic information.

[0072] The full-stroke functional operation verification requires the traverse component and bending roll component to continuously complete at least five full-stroke reciprocating movements without jamming under test pressure. This verification aims to simulate the dynamic performance of the rolling mill cylinder block in actual operation, ensuring that the repaired traverse component and bending roll component can smoothly and steadily complete their predetermined reciprocating movements under working pressure without any jamming. Five consecutive reciprocating movements are sufficient to verify the repeatability and reliability of the movement, while "jamming-free" emphasizes the smoothness of the movement, avoiding movement obstruction caused by excessive friction, improper fit clearance, or poor assembly. In practice, the repaired cylinder block assembly can be mounted on a dedicated functional test bench, and a test pressure consistent with actual working conditions (e.g., the same as or slightly lower than 28 MPa for sealing tests) is applied through a hydraulic system. Then, the traverse component and bending roll component are driven by the control system to perform full-stroke extension and reciprocating movements. Operators or automated systems monitor the smoothness of the movement through visual observation, auditory judgment, and motion trajectory sensors (such as displacement sensors) to ensure that there are no pauses, vibrations, or abnormal noises throughout the entire stroke. Alternatively, an automated testing system integrating displacement and force sensors can be used. Under test pressure, the system precisely controls the traverse and bending roller components to perform at least five full-stroke reciprocating motions. By analyzing the displacement-time and force-displacement curves, the smoothness of the motion, speed consistency, and the presence of abnormal resistance peaks can be quantified, thus objectively determining whether jamming occurs. Simultaneously, the completion time of each reciprocating motion can be recorded to evaluate its response speed.

[0073] In this embodiment, through the aforementioned technical solution, a more rigorous and comprehensive testing method is provided for the repaired rolling mill cylinder block during the integrated assembly and verification phase. Specifically, the sealing pressure test adopts a staged pressure increase method from low to high pressure, which effectively avoids secondary damage that may be caused by direct high-pressure impact and allows potential micro-leakage points to be gradually discovered and located at different pressure stages, thereby improving the safety and diagnostic efficiency of the test. Simultaneously, holding the pressure at 28 MPa for 30 minutes fully simulates the long-term operating state of the rolling mill cylinder block under actual high-load conditions, ensuring the reliability and durability of the sealing system under continuous high pressure, and significantly reducing the risk of leakage in the repaired cylinder block during actual use. Furthermore, the full-stroke functional motion verification requires the traverse component and the bending roll component to continuously complete at least five jam-free full-stroke reciprocating motions under test pressure. This not only verifies the dynamic performance and motion smoothness of the components under real load conditions, but also eliminates the possibility of occasional jamming through multiple reciprocating motions, ensuring that the repaired cylinder block can achieve precise and smooth motion control in actual production, thereby guaranteeing the stability of the rolling process and product accuracy. The setting of these specific parameters and procedures together improves the systematicness and repeatability of the verification process, providing a solid guarantee for repair quality and effectively solving the problem of insufficient testing and unreliability caused by the lack of specific parameters and standardized procedures in traditional testing methods.

[0074] Optionally, after the integrated assembly and verification steps, the method further includes: performing painting and data archiving, spraying anti-rust paint on the verified cylinder block assembly, and associating and storing the scan data, process parameters, inspection records and test reports involved in this repair with the unique identification code of the cylinder block assembly.

[0075] Specifically, coating and data archiving refer to the surface protection treatment of the repaired and validated cylinder assembly at the end of the rolling mill cylinder block repair process, and the systematic recording and storage of key information throughout the repair process. Coating aims to form a protective layer on the cylinder assembly surface to effectively resist environmental corrosion, while data archiving aims to establish a complete traceability chain for the repair process. Coating can be achieved in various ways, such as high-pressure airless spraying or air-assisted spraying to ensure uniform coverage and strong adhesion of the anti-rust paint film; alternatively, electrostatic spraying or dip coating can be used to adapt to cylinder assemblies with different geometries and improve paint utilization efficiency. Data archiving can be achieved by entering relevant information into the database module of an Enterprise Resource Planning (ERP) system or Manufacturing Execution System (MES) and linking it to the cylinder assembly's serial number or asset code; alternatively, a dedicated repair file management system can be established, using QR codes or RFID tags as unique identification codes to enable rapid access to electronic files.

[0076] When applying rust-preventive paint to validated cylinder block assemblies, the purpose is to apply a protective rust-preventive coating to the metal surface after the assembly has passed rigorous functional and sealing tests. This rust-preventive paint effectively isolates oxygen, moisture, and other corrosive media from the air, significantly slowing down or preventing oxidation and corrosion on the metal surface. In this way, the surface integrity and performance of the repaired cylinder block assembly are ensured to remain unaffected by environmental factors during storage, transportation, or before it is put into use, thus extending its overall service life.

[0077] Simultaneously, the scanning data, process parameters, inspection records, and test reports involved in this repair are linked and stored with the unique identification code of the cylinder block assembly, aiming to establish a comprehensive and traceable repair history archive. By assigning a unique identification code to each repaired cylinder block assembly, and using this code as an index, all relevant data, including the 3D scanning data obtained during the digital inspection phase, various process parameters set during the repair process (such as laser cladding power and speed), inspection records of key stages (such as dimensional measurements and surface roughness test results), and the final sealing pressure test and functional action verification report, are centrally stored and linked. This systematic data management approach enables the rapid and accurate retrieval of its complete repair history information when future maintenance, fault diagnosis, or repair of the cylinder block assembly is required, greatly improving management efficiency, decision-making accuracy, and the traceability of the repair process.

[0078] In this embodiment, through the above-described technical solution, after the integrated assembly and verification steps, the verified cylinder block assembly is sprayed with anti-rust paint, providing immediate and effective physical protection for the repaired cylinder block assembly. This directly solves the problem that the cylinder block assembly may corrode during long-term storage or use due to the lack of effective anti-rust measures after verification, thus ensuring the durability of the repair quality and extending the service life of the components. Simultaneously, the scanning data, process parameters, inspection records, and test reports involved in this repair are associated with and stored with the unique identification code of the cylinder block assembly, constructing a complete repair history archive. This solves the problem of data loss during future repairs or maintenance due to the lack of systematic management of key data during the repair process, significantly improving the traceability, management efficiency, and convenience of future maintenance. This strategy of protecting and archiving data only after rigorous verification avoids resource investment in unqualified components, optimizes the efficiency and cost-effectiveness of the overall repair process, and ensures that the rolling mill cylinder block assembly delivered to the user is not only functionally intact but also has traceable quality assurance and a longer service life.

[0079] Optionally, the method is used to repair the balance block of a hot rolling roughing mill and / or the continuously variable crown control block of a hot rolling finishing mill; when the repair object is a combined continuously variable crown control block, the systematic decomposition step includes separating it into independent individual components, and the graded repair execution step includes repairing each individual component separately and then performing combined processing to ensure overall accuracy.

[0080] Specifically, the method can be applied to repair the balance block used in hot rolling roughing mills to balance the roll weight and adjust the rolling force, ensuring its stability and accuracy under heavy loads; or to repair the continuously variable crown control block used in hot rolling finishing mills to precisely control the roll crown and optimize the strip shape quality, restoring its high-precision adjustment capability. When the repair object is a combined continuously variable crown control block, the combined control block can be assembled from multiple hydraulic cylinders, connecting plates, and guide mechanisms using bolts or pins, or it can contain multiple independent chambers and piston units, achieving a modular structure with integrated design to realize the overall function. For such combined structures, the systematic decomposition steps, based on conventional disassembly, further include identifying and disassembling the fasteners connecting each individual component, and carefully separating each individual component to avoid secondary damage during the decomposition process; or using special tooling fixtures to assist in the separation of individual components, ensuring the stability and safety of the separation process, and performing preliminary inspection and classification on each separated individual component. Subsequently, the graded repair execution steps include repairing each individual component separately. For example, based on their respective wear conditions and functional requirements, they may be independently subjected to dimensional restoration, surface strengthening, or component replacement. This could involve laser cladding on one individual component and precision grinding on another. After the repair of each individual component is completed, assembly processing is performed. That is, before or during assembly, the repaired individual components undergo overall precision machining. For example, multiple repaired individual components may be temporarily assembled and then subjected to overall surface grinding or boring to eliminate accumulated errors and ensure final assembly accuracy. Through the above strategy, the overall accuracy of the repaired modular control block can be guaranteed. This overall accuracy can be verified by measuring key dimensions and geometric tolerances (such as flatness, parallelism, and coaxiality) after assembly processing and comparing them with the original design drawings. It can also be evaluated through simulated assembly and functional testing to ensure coordinated movement and functional realization of each individual component after assembly.

[0081] In this embodiment, the above-described technical solution addresses the repair of the combined continuously variable crown control block. By refining the systematic decomposition steps into separating it into independent individual components and repairing each component separately, this effectively avoids precision loss caused by interference between components during the overall repair process. Furthermore, by assembling and processing the repaired individual components, the dimensional matching and geometric tolerances between them can be precisely coordinated, effectively eliminating cumulative errors that may occur during the repair of individual components. This ensures that the repaired combined continuously variable crown control block achieves a high standard of overall precision. This significantly improves the stable operation performance and shape control capability of the repaired cylinder block in the rolling mill, fundamentally solving the problem of difficulty in guaranteeing overall precision in the repair of combined cylinder blocks, and effectively avoiding functional deviations and performance instability after assembly.

[0082] Furthermore, the following more specific example will provide a deeper explanation of the above technical solution: A balance block from a hot rolling mill needs repair due to severe wear on its sliding plate surface, out-of-roundness of the transverse cylinder bore, and peeling of the coating on the piston rod surface caused by long-term operation.

[0083] First, a systematic disassembly process was conducted. After being sent to the specialized repair center, the rolling mill cylinder block underwent a cleaning process. Workers soaked the block in an alkaline chemical cleaner to thoroughly remove surface oil and attached iron oxide scale. Subsequently, stubborn rust was further removed using high-pressure water guns and mechanical grinding tools. During disassembly, it was found that some interference-fit pins and rusted threaded connections were difficult to separate. At this point, a thermal disassembly process was used, applying localized induction heating to these areas to cause thermal expansion, thus facilitating disassembly and preventing damage to the components. The balance block was then disassembled into its independent body, lateral movement components, and bending roll components. In the component separation process, the lateral movement sleeve, locking plate, and spacer sleeve in the lateral movement components were carefully separated one by one. All disassembled parts, including worn piston rods, guide copper sleeves, and seals, were inventoried according to the used parts management procedure, uniquely labeled, and their wear and corrosion status were recorded in detail to provide a basis for subsequent repair decisions.

[0084] Next comes digital inspection and solution generation. High-precision 3D scanning is performed on the disassembled cylinder block body, lateral movement components, and bending roller components to obtain point cloud data of their geometry. Simultaneously, key dimensional measurements are performed; for example, a laser tracker is used to measure the flatness and surface roughness of the cylinder block body's sliding plate surface, and a coordinate measuring machine is used to measure its overall height. For the lateral movement cylinder, its inner diameter and roundness are measured; for the piston rod, its outer diameter is measured. These measurement data are then precisely compared and analyzed with the original 3D design model of the balance block to identify all areas of wear, deformation, or dimensional deviations. Based on the comparison results, the system automatically generates a detailed repair process plan. This plan clearly specifies the target dimensions after repair (e.g., the flatness of the sliding plate surface is restored to within 0.02 mm), areas requiring material thickening (e.g., the sliding plate surface needs laser cladding to thicken by 0.8 mm), and specific machining paths such as the cutting depth and feed rate for subsequent machining.

[0085] The tiered repair process then commences. Based on the aforementioned repair plan, the key functional surfaces of the cylinder block body, namely the sliding plate surface, are restored to their dimensions and performance using laser cladding. Before laser cladding, the sliding plate surface is precision milled to achieve preset flatness (e.g., flatness 0.05 mm) and roughness (e.g., Ra 1.6 micrometers) requirements, providing an ideal substrate for cladding. During cladding, a synchronous powder feeding process is employed, with real-time monitoring of the molten pool temperature using an infrared thermal imager. The laser output power and scanning head movement speed are controlled in a closed-loop manner within a preset temperature range (e.g., 850℃ ± 50℃) to ensure uniform cladding layer structure and stable performance. For geometric root areas where the laser beam cannot effectively cover or where cladding quality is difficult to guarantee, such as the transition radius between the sliding plate surface and the sidewall, mechanical polishing is used for separate treatment to achieve the specified surface dimensions and quality requirements. After laser cladding, the cladding layer undergoes stress-relief annealing to eliminate residual stress generated during the cladding process and improve the fatigue life of the repaired part.

[0086] Simultaneously, worn or failed parts in the traverse and bending roll components are repaired or replaced. For example, the worn surface of the locating key on the mill cylinder block is laser-clad and then ground to the target thickness to ensure that the single-sided clearance after assembly with the frame is between 0.05 mm and 0.1 mm. For the piston rod, the process of removing the old chromium layer, grinding and correcting the substrate, re-plating with hard chromium, and finally precision grinding to the drawing dimensions is performed sequentially to restore its wear resistance and fitting accuracy. The inner hole of the guide copper sleeve is bored and a wear-resistant lubricating coating is prepared on its surface using a thermal spraying process. The worn sealing surface of the end cap is overlaid with copper alloy and then machined to the specified dimensions and geometric tolerances. In addition, the oil inlet flange is modified, including enlarging the diameter of the original mating hole, replacing it with a larger diameter connecting bolt, and replacing the hydraulic pipe fitting with a standard fitting with a higher rated pressure to accommodate higher working pressures.

[0087] Finally, integrated assembly and verification are performed. All repaired or replaced components are cleaned and then integrated according to strict assembly specifications, with new seals installed. After assembly, a sealing pressure test is conducted on the cylinder block assembly. The test is conducted by gradually increasing the pressure from low (e.g., 5 MPa) to high (e.g., 28 MPa), and holding at 28 MPa for 30 minutes to check for any leaks. Subsequently, full-stroke functional operation verification is performed, requiring the traversing component and bending roller component to continuously complete at least five full-stroke reciprocating movements without jamming under the test pressure, verifying their smooth operation and functional reliability.

[0088] Following the integrated assembly and verification steps, the method also includes painting and data archiving. Rust-preventive paint is applied to all verified cylinder block assemblies for surface protection. Simultaneously, all data related to this repair, including 3D scan data, laser cladding process parameters, critical dimension inspection records, sealing test reports, and functional operation verification reports, are linked to the unique identification code of the cylinder block assembly and stored to establish a complete repair file for easy traceability and management.

[0089] Through the above-mentioned systematic and precise repair process, the repair quality and precision of the rolling mill cylinder block have been significantly improved. This has solved the problems of reliance on experience, large quality fluctuations, difficulty in guaranteeing precision, and lack of systematic verification in traditional repair methods, effectively extending the service life of the cylinder block and reducing operating costs.

[0090] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for repairing rolling mill cylinder blocks, characterized in that, Includes the following steps: The system is decomposed into an independent body, transverse movement components, and bending roll components; Digital inspection and solution generation involves 3D scanning and key dimension measurement of the disassembled components, comparing the measurement data with the original design model, and generating a repair process solution that includes specific repair target dimensions, material thickening areas, and processing paths. The graded repair is carried out according to the repair process plan. The key functional surfaces of the cylinder block body are restored in size and performance by laser cladding process, and the worn or failed parts in the transverse component and the bending roller component are repaired or replaced. Integrated assembly and verification involves cleaning and assembling all repaired components, and then sequentially performing sealing pressure tests and full-stroke functional verification on the assembled cylinder block assembly.

2. The method for repairing rolling mill cylinder blocks according to claim 1, characterized in that, The systematic decomposition specifically includes: The cleaning process uses a combination of chemical cleaning agent soaking and mechanical polishing to remove oil, oxide scale and rust from the surface of the parts; The hot disassembly process involves locally heating the interference fit or rusted threaded connection parts before disassembly. The component separation process involves separating the transverse sleeve, locking plate, and spacer sleeve from each other in the transverse component. The old parts management process involves counting, labeling, and recording the status of disassembled parts according to their categories.

3. The method for repairing rolling mill cylinder blocks according to claim 1, characterized in that, In the aforementioned digital detection and solution generation steps The key dimension measurements include the flatness, surface roughness, and total height of the sliding plate surface of the cylinder block body, as well as the inner diameter and roundness of the transverse cylinder and the outer diameter of the piston rod; The repair process specifically specifies the thickness of the laser cladding layer, the cutting depth of machining, and the feed rate.

4. The method for repairing rolling mill cylinder blocks according to claim 3, characterized in that, In the graded repair execution steps, the laser cladding of the key functional surfaces adopts a synchronous powder feeding process. During the cladding process, the temperature of the molten pool is monitored by an infrared thermal imager, and the output power of the laser and the moving speed of the scanning head are controlled in a closed loop according to the preset temperature range.

5. The method for repairing rolling mill cylinder blocks according to claim 4, characterized in that, In the graded repair process, when performing laser cladding repair on the sliding plate surface of the cylinder block body, for the geometric root area that cannot be effectively covered by the laser beam or where the cladding quality is difficult to guarantee, a mechanical polishing process is used for separate treatment to achieve the specified surface dimensions and quality requirements.

6. The method for repairing rolling mill cylinder blocks according to claim 4, characterized in that, Before the laser cladding process is performed, the key functional surfaces are precision milled to ensure that their surfaces meet the preset flatness and roughness requirements. After the laser cladding process is completed, the cladding layer is subjected to stress-relief annealing.

7. The method for repairing rolling mill cylinder blocks according to claim 1, characterized in that, The repair of worn or failed parts in the graded repair process includes at least one of the following: The worn surface of the positioning key of the rolling mill cylinder block is laser clad and then ground to the target thickness dimension, which is such that the single-sided gap between the key and the frame after assembly is between 0.05 mm and 0.1 mm. The piston rod of the rolling mill cylinder block is subjected to the following processes in sequence: removal of the old chromium layer, grinding and correction of the substrate, re-plating of hard chromium, and finally precision grinding to the dimensions shown in the drawing. The inner hole of the guide copper sleeve of the rolling mill cylinder block is bored, and a wear-resistant and lubricating coating is prepared on its surface by thermal spraying. The worn sealing surface of the end cover of the rolling mill cylinder block is welded with copper alloy and then machined to the specified dimensions and dimensional tolerances. The modification of the oil inlet flange of the rolling mill cylinder block includes enlarging the diameter of the original connecting hole, replacing it with a larger diameter connecting bolt, and replacing the hydraulic pipe joint with a standard joint with a higher rated pressure.

8. The method for repairing rolling mill cylinder blocks according to claim 1, characterized in that, The sealing pressure test in the integrated assembly and verification steps is carried out by gradually increasing the pressure from low pressure to high pressure and holding it at 28MPa for 30 minutes; the full-stroke functional action verification requires the transverse component and the bending roller component to continuously complete at least five full-stroke reciprocating movements without jamming under the test pressure.

9. The method for repairing rolling mill cylinder blocks according to claim 8, characterized in that, Following the integrated assembly and verification steps, the method further includes: performing painting and data archiving, spraying anti-rust paint on the verified cylinder block assembly, and associating and storing the scan data, process parameters, inspection records and test reports involved in this repair with the unique identification code of the cylinder block assembly.

10. The method for repairing rolling mill cylinder blocks according to claim 1, characterized in that, The method is used to repair the balance block of a hot rolling roughing mill and / or the continuously variable crown control block of a hot rolling finishing mill. When the object to be repaired is the combined continuously variable crown control block, the systematic decomposition step includes separating it into independent individual components, and the graded repair execution step includes repairing each individual component separately and then performing combined processing to ensure overall accuracy.

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