A process method for installing and calibrating a D-box of a reducing sizing mill set

Abstract

The application relates to the technical field of steel rolling equipment, and discloses a D-box mounting and calibration process method of a reducing sizing unit, which comprises the following steps: S1, process preparation before the process; S2, reference positioning and calibration; S3, layered installation of a composite bearing group; S4, adaptive installation of a gear shaft and an oil supply system; S5, locking, fixing, whole-process precision checking and S6, process protection and recording after the process, so that the bearing service life is greatly prolonged, and the fault frequency is significantly reduced; the composite bearing group structure of "a double-row cylindrical roller bearing in the middle + two tapered roller bearings on the two sides" is innovatively adopted, accurate clearance control is carried out, scientific load distribution is realized, the cylindrical roller bearing bears 70%-80% of the radial load, the tapered roller bearing focuses on bearing axial load and a small amount of radial load, and the equivalent load of the original bearing is reduced to below 50%. In combination with fine treatment of a bearing matching surface and whole-process coaxiality control, the bearing service life is prolonged by more than 10 times compared with the original scheme, the problem of plastic deformation failure of the bearing is completely solved, and the operation and maintenance stability is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of steel rolling equipment technology, specifically to a process method for installing and calibrating the D-box of a reducing and sizing mill unit. Background Technology

[0002] The D-box (reducer) of the sizing and reducing mill is the core transmission equipment for achieving precise sizing and reducing of steel in the steel rolling production line. Its installation and calibration quality directly determines the rolling accuracy of steel, the continuous stability of production, and the overall operation and maintenance cost. It is a key link to ensure the efficient advancement of high-speed wire rod production.

[0003] In the existing installation process in this technical field, the core defect is mainly reflected in the unreasonable design and assembly logic of the bearing system: the traditional D-box gear shaft bearings generally adopt the "double row tapered roller bearing back-to-back installation" structure. This type of bearing needs to bear both radial and axial loads at the same time, but its radial load capacity is inherently insufficient. Under the high frequency and high load operation conditions of the unit, the bearing rolling elements and raceways are prone to plastic deformation failure, resulting in frequent equipment failures.

[0004] Meanwhile, traditional processes lack standardized benchmark calibration procedures and component interchangeability designs, and the original oil supply structure is easily blocked, resulting in insufficient lubrication, which further aggravates bearing wear. This not only leads to the risk of serious gear tooth breakage, but also results in cumbersome maintenance procedures, long downtime, significantly increased maintenance load and spare parts consumption, seriously affecting production continuity and significantly increasing enterprise operation and maintenance costs. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a process for installing and calibrating the D-box of a reducing sizing unit. This process significantly extends bearing life and reduces the frequency of failures. It also solves the problem that the original oil supply structure is easily blocked, resulting in insufficient lubrication and further aggravating bearing wear.

[0006] (II) Technical Solution To achieve the aforementioned goal of significantly extending bearing life and significantly reducing failure frequency, this invention provides the following technical solution: a process method for installing and calibrating the D box of a sizing and reducing unit, including S1 pre-process preparation, S2 benchmark positioning calibration, S3 layered installation of composite bearing components, S4 gear shaft and oil supply system adaptation installation, S5 locking and fixing and full-process accuracy verification, and S6 post-process protection and recording. The S1 pre-process preparation includes S1.1 component inspection, S1.2 component pretreatment, and S1.3 preparation of tools and auxiliary materials. Among them, S2 reference positioning calibration includes S2.1D box body reference calibration and S2.2 bearing seat precision fixing; Among them, the S3 composite bearing component layered installation includes the installation of double-row cylindrical roller bearings in the middle of S3.1 and tapered roller bearings on both sides of S3.2; The S4 gear shaft and oil supply system adaptation installation includes S4.1 precise assembly of the gear shaft and S4.2 installation and calibration of the oil supply system. Among them, S5 locking and fixing and full-process accuracy verification includes S5.1 graded locking and fixing, S5.2 static accuracy detection and S5.3 dynamic trial operation verification; Among them, S6 post-process protection and recording includes S6.1 all-round protection treatment and S6.2 complete file retention.

[0007] Preferably, the S1.1 component inspection: Composite bearing assembly: Double-row full complement cylindrical roller bearings with an inner diameter of 135~175mm, an outer diameter of 205~245mm, and a width of 90~115mm, a basic rated dynamic load ≥780~980kN, and a limiting speed of 1200~1900r / min; Single-row tapered roller bearings with an inner diameter of 135~175mm, an outer diameter of 205~245mm, and a width of 42~54mm, a basic rated dynamic load ≥310~440kN, and a limiting speed of 2000~3000r / min, free from cracks and excessive raceway wear; Gear shaft: outer diameter tolerance grade H7~n6, shoulder end face runout ≤0.02~0.05mm, gear helix angle 8°~15°, total axial force to radial force ratio Fx / Fr=0.45~0.65, journal free from scratches and excessive wear; Auxiliary components: bearing housing inner diameter 140~180mm (roundness tolerance ≤0.03~0.07mm), end cover flatness error ≤0.02~0.05mm / m; oil supply pipe diameter 8~12mm, smooth inner wall without rust or blockage, pressure resistance ≥1.5MPa; sealing gasket thickness 0.5~1.0mm, without damage or deformation; S1.2 Component Pretreatment: Cleaning: Mechanical grinding and special cleaning agent are used to thoroughly remove iron oxide scale, oil stains and old grease residue from the surface. The surface finish of the bearing mating surface is ≤Ra0.8~1.2μm, with no attachments that may affect assembly accuracy. Activation and lubrication: Lightly grind and activate the gear shaft journal and bearing inner hole, and evenly apply assembly lubricating oil with a viscosity grade of 20~45, with an oil film thickness of ≤0.03mm, to ensure smooth assembly without jamming; Defect investigation: Inspect all components one by one to ensure there are no cracks, deformations, or thread damage, and that bolts, washers, and other auxiliary parts are of the correct specifications.

[0008] Preferably, the preparation of tools and auxiliary materials in step S1.3 is as follows: Core tools: coaxiality gauge (range 0~300mm, accuracy 0.01mm), torque wrench (range 0~600N・m), bearing clearance gauge (range 0~0.5mm, accuracy 0.001mm), laser level (accuracy 0.02mm / m), special lifting fixtures (load capacity ≥100kg), dial indicator (accuracy 0.001mm), pressure gauge (range 0~1.0MPa, accuracy 0.01MPa); Supporting materials: high-temperature resistant grease (temperature resistance ≥180℃, dropping point ≥220℃), oil-resistant sealant, rust inhibitor, adjustable positioning pins (diameter 15~22mm), adjusting shims (thickness 0.1~0.5mm), anti-loosening washers, and dust-free wiping cloth.

[0009] Preferably, the S2.1D enclosure reference calibration is performed as follows: Horizontal fixation: Place the D box body stably on the horizontal assembly platform. The platform levelness error is ≤0.02~0.04mm / m. Level it with no more than 3 shims to ensure that the box body mounting surface is flat, stable and without shaking. Verticality calibration: Use a laser level to check the verticality of the mounting surface of the cabinet. The deviation should be ≤0.03~0.08mm / m. If the deviation exceeds the standard, adjust the position of the shims or grind the mating surface of the cabinet until the standard is met. Coaxiality test: Use a coaxiality test gauge to test the coaxiality of the bearing housing mounting holes at both ends of the housing. The allowable deviation is ≤0.04~0.09mm. If the deviation exceeds the standard, grind the inner wall of the bearing housing mounting holes to correct it and ensure accurate installation reference. S2.2 bearing housing precisely fixed: Adhesive application and positioning: Apply 0.1~0.3mm thick oil-resistant sealant evenly to the mating surface of the bearing housing and the housing. After hoisting the bearing housing, calibrate its center to be coaxial with the center hole of the housing. The deviation should be ≤0.03~0.07mm. Positioning pin fixing: Insert 6 to 8 adjustable positioning pins evenly distributed around the circumference, with an insertion depth of ≥35 to 45 mm and a fitting clearance of 0.01 to 0.04 mm to prevent assembly displacement; Cross-locking: Use a torque wrench to tighten the fixing bolts in a cross-symmetrical manner step by step. The torque should be controlled between 180 and 250 N·m. After tightening, use a feeler gauge to check that the fit gap is ≤0.03 to 0.06 mm to ensure a tight fit.

[0010] Preferably, the double-row cylindrical roller bearing in the middle of S3.1 is installed as follows: Grease application and assembly: Apply high-temperature resistant grease evenly to the inner hole of the bearing housing and the outer surface of the bearing, with an oil film thickness of 0.03~0.06mm, and slowly press it into the preset middle position to avoid damaging the bearing by forced impact; Clearance adjustment: Use a bearing clearance tester to check the radial clearance and control it within 0.02~0.06mm. If it does not meet the standard, replace the adjusting shims (0.1~0.5mm) to correct it and ensure that the radial load capacity meets the standard. Fit verification: Observe the fit between the bearing end face and the shaft shoulder to ensure there is no gap or wobble and the fit is tight enough to meet the requirements.

[0011] Preferably, the tapered roller bearings on both sides of S3.2 are installed as follows: Symmetrical assembly: Tapered roller bearings are symmetrically press-fitted on both sides of the cylindrical roller bearing, and the position is adjusted to control the axial movement of the gear shaft within 0.03~0.08mm to ensure reasonable axial clearance; Load distribution optimization: The clearance of the tapered roller bearing is precisely controlled (0.01~0.04mm) by a bearing clearance detector to achieve scientific load distribution—the cylindrical roller bearing bears 70%~80% of the radial load, and the tapered roller bearings on both sides each bear all the axial load and 10%~15% of the radial load, avoiding overload failure of a single bearing; Coaxiality verification: Use a dial indicator to check that the overall coaxiality of the bearing assembly's inner bore is ≤0.03~0.07mm, and the circular runout of the bearing end face is ≤0.02~0.05mm, to ensure smooth operation without off-center load.

[0012] Preferably, the S4.1 gear shaft is precisely assembled: Smooth insertion: Slowly insert the pre-treated gear shaft into the inner hole of the bearing assembly, ensuring that the keyway and the inner ring positioning groove of the bearing are precisely aligned (deviation ≤0.03~0.06mm). There should be no forced impact or prying operation throughout the process to avoid damage to the journal and the inner hole of the bearing. Position calibration: Use a dial indicator to check that the parallelism error between the gear end face and the housing reference surface is ≤0.03~0.06mm / m, and adjust the gear meshing clearance to 0.15~0.35mm to ensure smooth transmission without impact; Interchangeability Guarantee: The spare gear shaft is pre-processed according to the parameters of the existing components throughout the entire process. The journal size and keyway position are consistent with the key parameters. When interchangeable and assembled, the coaxiality deviation is ≤0.04~0.08mm, and no additional processing is required. The gear shaft and bearing assembly are matched and numbered one-to-one to facilitate quick identification and adaptation in the future.

[0013] Preferably, the S4.2 oil supply system is installed and calibrated: Oil pipe positioning: Fix the new oil supply pipe at the preset position of the bearing housing end cover to ensure that the outlet is accurately aligned with the lubrication channel of the bearing assembly. The distance between the outlet and the bearing end face is 3~8mm to ensure that the lubricating oil is accurately sprayed to the contact surface between the rolling elements and the raceway. Sealing test: Introduce 0.3~0.6MPa compressed air into the oil supply system, maintain the pressure for 5~10 minutes, and observe that there is no leakage at the oil pipe interface and end cap, and the pressure does not drop significantly, which is considered qualified; Vibration-resistant fixing: Use special clips to firmly fix the oil pipes to prevent them from shifting or falling off due to vibration during unit operation.

[0014] Preferably, the S5.1 staged locking and fixing: End cap bolt tightening: Use a cross-symmetrical step-by-step tightening method to tighten the gear shaft end cap bolts, with the torque controlled at 80~120N・m to avoid local stress concentration that could cause end cap deformation; Bearing housing reinforcement and locking: Check the torque of the bearing housing fixing bolts to ensure that it is maintained at 180~250N・m; add anti-loosening washers or spot weld anti-loosening to all exposed bolts (2~3 weld points, weld point diameter ≤3mm) to prevent bolts from loosening during high-speed operation; S5.2 Static Precision Inspection: Core precision testing: The overall coaxiality of the gear shaft and the center hole of the housing is ≤0.04~0.09mm; the radial runout of the gear shaft is ≤0.02~0.05mm; the axial movement is ≤0.03~0.08mm; the coaxiality of the bearing assembly inner hole is ≤0.03~0.07mm. Fitting gap inspection: The fitting gap between the bearing housing and the housing is ≤0.03~0.06mm, and the positioning deviation of the oil supply pipe is ≤0.5~1.0mm, to ensure accurate positioning of each component and smooth lubrication path; S5.3 Dynamic Trial Operation Verification: No-load test: Start the D-box for no-load test run, gradually increase the speed from 500~800r / min to the rated speed of 1500~2000r / min, and continue for 30~60 minutes. The unit should have no abnormal vibration (vibration value ≤2.0~3.0mm / s), no abnormal noise, and the bearing temperature ≤70℃. Load test: After rolling 6.0~10.0mm steel and running continuously for 20~40 hours, the bearing temperature is ≤70~85℃, the gear meshing is smooth and without impact, the oil supply system has no leakage, the bearing assembly has no wear noise, and the equivalent load of the tapered roller bearing does not exceed 50% of the original design.

[0015] Preferably, the S6.1 all-around protective treatment: Rust prevention: Apply rust inhibitor evenly to the exposed surfaces of the gear shaft end, bearing housing end cover, and oil pipe interface to form a protective film and prevent air and moisture from corroding and rusting; Dustproof: The input / output terminals of the D box are fully covered with a special protective cover to prevent dust and impurities from entering the interior and affecting the operation of the components; Labeling: Mark the installation date, component matching number, and operator information in a prominent position on box D for easy traceability and maintenance; Complete S6.2 file retained: Record content: Record in detail all key information including core component parameters, assembly clearance, bolt torque, bearing clearance adjustment data, static test results, and trial operation status; Archiving requirements: Establish dual electronic and paper archives, clarify the interchangeability parameter standards of components, provide accurate basis for subsequent maintenance and component replacement, and improve maintenance efficiency.

[0016] (III) Beneficial Effects Compared with the prior art, the present invention provides a method for the installation and calibration of the D-box of a reducing sizing unit, which has the following beneficial effects: 1. The installation and calibration process of the D box of the sizing and reducing unit significantly extends bearing life and reduces failure frequency. It innovatively adopts a composite bearing assembly structure of "double-row cylindrical roller bearings in the middle + tapered roller bearings on both sides." Through precise clearance control (0.01~0.04mm for tapered roller bearings), scientific load distribution is achieved—the cylindrical roller bearings bear 70%~80% of the radial load, while the tapered roller bearings focus on bearing axial load and a small amount of radial load, reducing the original bearing equivalent load to below 50%. Combined with refined treatment of bearing mating surfaces (surface finish ≤Ra0.8~1.2μm) and full-process coaxiality control (≤0.03~0.09mm), the bearing service life is extended by more than 10 times compared to the original solution, completely solving the problem of bearing plastic deformation failure, significantly reducing equipment failure frequency, and significantly improving operational stability.

[0017] 2. The installation and calibration process of the D box of the reducing and sizing unit has improved maintenance efficiency and significantly reduced downtime: Through standardized pre-processing of the spare gear shaft and one-to-one matching marking design, the components are fully interchangeable. The coaxiality deviation during interchange assembly is ≤0.04~0.08mm, requiring no additional processing or adjustment. Combined with the standardized process of benchmark calibration and layered installation, the maintenance time is reduced by more than 50% compared with the original level, effectively reducing production interruption losses and significantly improving production continuity.

[0018] 3. The installation and calibration process of the D box of the reduced sizing unit has achieved significant cost savings in operation and maintenance, resulting in outstanding economic benefits: the bearing life is extended and the failure frequency is reduced, which can reduce the cost of bearing spare parts consumption by 100,000 yuan per year; the maintenance process is simplified and the time is shortened, which reduces the annual maintenance labor and auxiliary costs by 50,000 yuan; at the same time, the unit's operational stability is improved, avoiding additional losses caused by serious gear tooth breakage failures, resulting in a comprehensive benefit of 150,000 yuan per year, with significant overall economic benefits.

[0019] 4. The installation and calibration process of the D box of the sizing and reducing mill unit has improved operational reliability and ensured rolling accuracy: a full-process benchmark calibration system with the center hole of the box as the core has been established, and the coaxiality and fitting gap of each component have been strictly controlled. The gear meshing gap has been precisely adjusted (0.15~0.35mm) to keep the vibration value of the unit within 2.5mm / s. The newly added oil supply pipe is precisely positioned (the outlet is 3~8mm from the bearing end face) to ensure that there are no blind spots in lubrication, further improving the operational stability of the components and providing a reliable guarantee for the rolling accuracy of steel.

[0020] 5. The installation and calibration process of the D-box of the reducing and sizing unit is widely adaptable and easy to operate, with high promotion value: the process covers the assembly needs of D-boxes of various specifications with bearings of 135~175mm inner diameter and gear helix angle of 8°~15°, and the tools and auxiliary materials used are all conventional and universal; the standardized parameter control, step-by-step operation process and dual file retention design reduce the dependence on the operator's experience and facilitate rapid promotion and application in various reducing and sizing units. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] This solution provides a technical approach, specifically a process for installing and calibrating the D-box of a sizing and reducing unit, comprising the following steps: S1 Pre-process preparation: Constructing a solid installation foundation (100% pre-treatment qualified before startup). S1.1 Component Inspection: (Expanded Parameter Range Control) Composite bearing assembly: Double-row full complement cylindrical roller bearings with an inner diameter of 135~175mm, an outer diameter of 205~245mm, and a width of 90~115mm, a basic rated dynamic load ≥780~980kN, and a limiting speed of 1200~1900r / min; Single-row tapered roller bearings with an inner diameter of 135~175mm, an outer diameter of 205~245mm, and a width of 42~54mm, a basic rated dynamic load ≥310~440kN, and a limiting speed of 2000~3000r / min, free from cracks and excessive raceway wear; Gear shaft: outer diameter tolerance grade H7~n6, shoulder end face runout ≤0.02~0.05mm, gear helix angle 8°~15°, total axial force to radial force ratio Fx / Fr=0.45~0.65, journal free from scratches and excessive wear; Auxiliary components: bearing housing inner diameter 140~180mm (roundness tolerance ≤0.03~0.07mm), end cover flatness error ≤0.02~0.05mm / m; oil supply pipe diameter 8~12mm, smooth inner wall without rust or blockage, pressure resistance ≥1.5MPa; sealing gasket thickness 0.5~1.0mm, without damage or deformation; S1.2 Component Pretreatment: Cleaning: Mechanical grinding and special cleaning agent are used to thoroughly remove iron oxide scale, oil stains and old grease residue from the surface. The surface finish of the bearing mating surface is ≤Ra0.8~1.2μm, with no attachments that may affect assembly accuracy. Activation and lubrication: Lightly grind and activate the gear shaft journal and bearing inner hole, and evenly apply assembly lubricating oil with a viscosity grade of 20~45, with an oil film thickness of ≤0.03mm, to ensure smooth assembly without jamming; Defect investigation: Inspect all components one by one to ensure there are no cracks, deformations, or thread damage that could pose a quality hazard, and that bolts, washers, and other auxiliary parts are of the correct specifications; S1.3 Preparation of tools and auxiliary materials: Core tools: coaxiality gauge (range 0~300mm, accuracy 0.01mm), torque wrench (range 0~600N・m), bearing clearance gauge (range 0~0.5mm, accuracy 0.001mm), laser level (accuracy 0.02mm / m), special lifting fixtures (load capacity ≥100kg), dial indicator (accuracy 0.001mm), pressure gauge (range 0~1.0MPa, accuracy 0.01MPa); Supporting materials: high-temperature resistant grease (temperature resistance ≥180℃, dropping point ≥220℃), oil-resistant sealant, rust inhibitor, adjustable positioning pins (diameter 15~22mm), adjusting shims (thickness 0.1~0.5mm), anti-loosening washers, and dust-free wiping cloth; S2 reference positioning calibration: Precisely anchors the core reference (coaxiality is controllable throughout). S2.1D enclosure reference calibration: Horizontal fixation: Place the D box body stably on the horizontal assembly platform. The platform levelness error is ≤0.02~0.04mm / m. Level it with no more than 3 shims to ensure that the box body mounting surface is flat, stable and without shaking. Verticality calibration: Use a laser level to check the verticality of the mounting surface of the cabinet. The deviation should be ≤0.03~0.08mm / m. If the deviation exceeds the standard, adjust the position of the shims or grind the mating surface of the cabinet until the standard is met. Coaxiality test: Use a coaxiality test gauge to test the coaxiality of the bearing housing mounting holes at both ends of the housing. The allowable deviation is ≤0.04~0.09mm. If the deviation exceeds the standard, grind the inner wall of the bearing housing mounting holes to correct it and ensure accurate installation reference. S2.2 bearing housing precisely fixed: Adhesive application and positioning: Apply 0.1~0.3mm thick oil-resistant sealant evenly to the mating surface of the bearing housing and the housing. After hoisting the bearing housing, calibrate its center to be coaxial with the center hole of the housing. The deviation should be ≤0.03~0.07mm. Positioning pin fixing: Insert 6 to 8 adjustable positioning pins evenly distributed around the circumference, with an insertion depth of ≥35 to 45 mm and a fitting clearance of 0.01 to 0.04 mm to prevent assembly displacement; Cross-locking: Use a torque wrench to tighten the fixing bolts in a cross-symmetrical manner step by step. The torque should be controlled between 180 and 250 N·m. After tightening, use a feeler gauge to check that the fit gap is ≤0.03 to 0.06 mm to ensure a tight fit. S3 composite bearings are installed in layers: optimizing load distribution (ensuring core functions). S3.1 Middle Double Row Cylindrical Roller Bearing Installation: Grease application and assembly: Apply high-temperature resistant grease evenly to the inner hole of the bearing housing and the outer surface of the bearing, with an oil film thickness of 0.03~0.06mm, and slowly press it into the preset middle position to avoid damaging the bearing by forced impact; Clearance adjustment: Use a bearing clearance tester to check the radial clearance and control it within 0.02~0.06mm. If it does not meet the standard, replace the adjusting shims (0.1~0.5mm) to correct it and ensure that the radial load capacity meets the standard. Fit verification: Observe the fit between the bearing end face and the shaft shoulder to ensure there is no gap or wobble and the fit is tight enough to meet the requirements; S3.2 Installation of tapered roller bearings on both sides: Symmetrical assembly: Tapered roller bearings are symmetrically press-fitted on both sides of the cylindrical roller bearing, and the position is adjusted to control the axial movement of the gear shaft within 0.03~0.08mm to ensure reasonable axial clearance; Load distribution optimization: The clearance of the tapered roller bearing is precisely controlled (0.01~0.04mm) by a bearing clearance detector to achieve scientific load distribution—the cylindrical roller bearing bears 70%~80% of the radial load, and the tapered roller bearings on both sides each bear all the axial load and 10%~15% of the radial load, avoiding overload failure of a single bearing; Coaxiality verification: Use a dial indicator to check that the overall coaxiality of the bearing assembly's inner bore is ≤0.03~0.07mm, and the circular runout of the bearing end face is ≤0.02~0.05mm, to ensure smooth operation without off-center load; S4 Gear Shaft and Oil Supply System Fitting Installation: Precise Fit + Functional Guarantee S4.1 gear shaft precision assembly: Smooth insertion: Slowly insert the pre-treated gear shaft into the inner hole of the bearing assembly, ensuring that the keyway and the inner ring positioning groove of the bearing are precisely aligned (deviation ≤0.03~0.06mm). There should be no forced impact or prying operation throughout the process to avoid damage to the journal and the inner hole of the bearing. Position calibration: Use a dial indicator to check that the parallelism error between the gear end face and the housing reference surface is ≤0.03~0.06mm / m, and adjust the gear meshing clearance to 0.15~0.35mm to ensure smooth transmission without impact; Interchangeability Guarantee: The spare gear shaft is pre-processed according to the parameters of the existing components throughout the entire process. The journal size and keyway position are consistent with the key parameters. When interchangeable and assembled, the coaxiality deviation is ≤0.04~0.08mm, and no additional processing is required. The gear shaft and bearing assembly are matched and numbered one-to-one to facilitate quick identification and adaptation in the future. S4.2 fuel supply system installation and calibration: Oil pipe positioning: Fix the new oil supply pipe at the preset position of the bearing housing end cover to ensure that the outlet is accurately aligned with the lubrication channel of the bearing assembly. The distance between the outlet and the bearing end face is 3~8mm to ensure that the lubricating oil is accurately sprayed to the contact surface between the rolling elements and the raceway. Sealing test: Introduce 0.3~0.6MPa compressed air into the oil supply system, maintain the pressure for 5~10 minutes, and observe that there is no leakage at the oil pipe interface and end cap, and the pressure does not drop significantly, which is considered qualified; Vibration-resistant fixing: Use special clips to secure the oil pipes firmly to prevent them from shifting or falling off due to vibration during unit operation; S5 locking and fixing with full-process precision verification: ensuring installation quality meets standards. S5.1 graded locking and fixing: End cap bolt tightening: Use a cross-symmetrical step-by-step tightening method to tighten the gear shaft end cap bolts, with the torque controlled at 80~120N・m to avoid local stress concentration that could cause end cap deformation; Bearing housing reinforcement and locking: Check the torque of the bearing housing fixing bolts to ensure that it is maintained at 180~250N・m; add anti-loosening washers or spot weld anti-loosening to all exposed bolts (2~3 weld points, weld point diameter ≤3mm) to prevent bolts from loosening during high-speed operation; S5.2 Static Precision Inspection: Core precision testing: The overall coaxiality of the gear shaft and the center hole of the housing is ≤0.04~0.09mm; the radial runout of the gear shaft is ≤0.02~0.05mm; the axial movement is ≤0.03~0.08mm; the coaxiality of the bearing assembly inner hole is ≤0.03~0.07mm. Fitting gap inspection: The fitting gap between the bearing housing and the housing is ≤0.03~0.06mm, and the positioning deviation of the oil supply pipe is ≤0.5~1.0mm, to ensure accurate positioning of each component and smooth lubrication path; S5.3 Dynamic Trial Operation Verification: No-load test: Start the D-box for no-load test run, gradually increase the speed from 500~800r / min to the rated speed of 1500~2000r / min, and continue for 30~60 minutes. The unit should have no abnormal vibration (vibration value ≤2.0~3.0mm / s), no abnormal noise, and the bearing temperature ≤70℃. Load test: After rolling 6.0~10.0mm steel and running continuously for 20~40 hours, the bearing temperature is ≤70~85℃, the gear meshing is smooth without impact, the oil supply system has no leakage, the bearing assembly has no wear noise, and the equivalent load of the tapered roller bearing does not exceed 50% of the original design. S6 Post-Process Protection and Recording: Ensuring Long-Term Stable Operation S6.1 All-round Protection Treatment: Rust prevention: Apply rust inhibitor evenly to the exposed surfaces of the gear shaft end, bearing housing end cover, and oil pipe interface to form a protective film and prevent air and moisture from corroding and rusting; Dustproof: The input / output terminals of the D box are fully covered with a special protective cover to prevent dust and impurities from entering the interior and affecting the operation of the components; Labeling: Mark the installation date, component matching number, and operator information in a prominent position on box D for easy traceability and maintenance; Complete S6.2 file retained: Record content: Record in detail all key information including core component parameters, assembly clearance, bolt torque, bearing clearance adjustment data, static test results, and trial operation status; Archiving requirements: Establish dual electronic and paper archives, clearly define the interchangeability parameters of components, provide accurate basis for subsequent maintenance and component replacement, and improve maintenance efficiency; Key process control points (that cannot be ignored) Reference priority: The center axes of the housing, bearing housing, bearing assembly, and gear shaft must be kept consistent. The coaxiality deviation must be strictly controlled throughout the process to avoid premature failure of the bearing due to reference offset. Controllable load: Strictly adjust the bearing clearance according to the preset clearance, adhere to the load distribution logic of "radial bearing for cylindrical roller bearings and axial bearing for tapered roller bearings", and do not adjust it arbitrarily; Lubrication is in place: The oil supply line is precisely positioned to ensure that the lubricating oil covers all rolling elements and raceways of the bearing, with no blind spots, thus avoiding insufficient lubrication that could lead to increased wear. Interchangeability guarantee: Spare parts are pre-processed and tested according to standardized parameters to ensure full compatibility with existing parts, allowing for rapid assembly without secondary processing and reducing downtime; Environmental requirements: The entire assembly process must be carried out in a dry, dust-free environment at a temperature of 10~35℃ to prevent impurities from entering and affecting assembly accuracy and component lifespan. Furthermore, this process significantly extends bearing life and reduces failure frequency: It innovatively adopts a composite bearing assembly structure of "double-row cylindrical roller bearings in the middle + tapered roller bearings on both sides," achieving scientific load distribution through precise clearance control (0.01~0.04mm for tapered roller bearings). The cylindrical roller bearings bear 70%~80% of the radial load, while the tapered roller bearings focus on bearing axial loads and a small amount of radial load, reducing the original bearing equivalent load to below 50%. Combined with refined treatment of bearing mating surfaces (surface finish ≤Ra0.8~1.2μm) and full-process coaxiality control (≤0.03~0.09mm), the bearing life is extended by more than 10 times compared to the original solution, completely solving the problem of bearing plastic deformation failure, significantly reducing equipment failure frequency, and significantly improving operational stability. Furthermore, this process method improves maintenance efficiency and significantly reduces downtime: through standardized pre-treatment of spare gear shafts and one-to-one matching marking design, complete interchangeability of parts is achieved, and the coaxiality deviation during interchange assembly is ≤0.04~0.08mm, requiring no additional processing or adjustment; combined with the standardized process of benchmark calibration and layered installation, maintenance time is reduced by more than 50% compared to the original level, effectively reducing production interruption losses and significantly improving production continuity; Furthermore, this process significantly reduces operation and maintenance costs and yields outstanding economic benefits: the extended bearing life and reduced failure frequency can reduce the cost of bearing spare parts consumption by 100,000 yuan per year; the simplified maintenance process and shortened time can reduce maintenance labor and auxiliary costs by 50,000 yuan per year; at the same time, the improved unit operation stability avoids additional losses caused by serious gear tooth breakage failures, resulting in a comprehensive benefit of 150,000 yuan per year, with significant overall economic benefits. Furthermore, this process improves operational reliability and ensures rolling precision: a full-process benchmark calibration system centered on the box's central hole is established, strictly controlling the coaxiality and fitting gap of each component, and precisely adjusting the gear meshing clearance (0.15~0.35mm) to keep the unit's vibration value within 2.5mm / s; the newly added oil supply pipe is precisely positioned (outlet 3~8mm from the bearing end face) to ensure lubrication without blind spots, further improving the operational stability of components and providing a reliable guarantee for the rolling precision of steel. Furthermore, this process method achieves wide adaptability and convenient operation, with high promotion value: the process covers the assembly needs of D-boxes of various specifications with bearings of 135~175mm inner diameter and gear helix angle of 8°~15°, and the tools and auxiliary materials used are all conventional and universal; the standardized parameter control, step-by-step operation process and dual file retention design reduce the dependence on the operator's experience, making it easy to promote and apply in various types of sizing and reducing units; Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for installing and calibrating the D-box of a reducing and sizing unit, comprising S1 pre-process preparation, S2 benchmark positioning calibration, S3 layered installation of the composite bearing assembly, S4 adaptation installation of the gear shaft and oil supply system, S5 locking and fixing and full-process accuracy verification, and S6 post-process protection and recording, characterized in that: The S1 process preparation includes S1.1 component inspection, S1.2 component pretreatment, and S1.3 tool and auxiliary material preparation. Among them, S2 reference positioning calibration includes S2.1D box body reference calibration and S2.2 bearing seat precision fixing; Among them, the S3 composite bearing group layered installation includes the installation of double-row cylindrical roller bearings in the middle of S3.1 and tapered roller bearings on both sides of S3.2; The S4 gear shaft and oil supply system adaptation installation includes S4.1 precise assembly of the gear shaft and S4.2 installation and calibration of the oil supply system. Among them, S5 locking and fixing and full-process accuracy verification includes S5.1 graded locking and fixing, S5.2 static accuracy detection and S5.3 dynamic trial operation verification; Among them, S6 post-process protection and recording includes S6.1 all-round protection treatment and S6.2 complete file retention.

2. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The S1.1 component inspection: Composite bearing assembly: Double-row full complement cylindrical roller bearings with an inner diameter of 135~175mm, an outer diameter of 205~245mm, and a width of 90~115mm, a basic rated dynamic load ≥780~980kN, and a limiting speed of 1200~1900r / min; Single-row tapered roller bearings with an inner diameter of 135~175mm, an outer diameter of 205~245mm, and a width of 42~54mm, a basic rated dynamic load ≥310~440kN, and a limiting speed of 2000~3000r / min, free from cracks and excessive raceway wear; Gear shaft: outer diameter tolerance grade H7~n6, shoulder end face runout ≤0.02~0.05mm, gear helix angle 8°~15°, total axial force to radial force ratio Fx / Fr=0.45~0.65, journal free from scratches and excessive wear; Auxiliary components: bearing housing inner diameter 140~180mm (roundness tolerance ≤0.03~0.07mm), end cover flatness error ≤0.02~0.05mm / m; oil supply pipe diameter 8~12mm, smooth inner wall without rust or blockage, pressure resistance ≥1.5MPa; sealing gasket thickness 0.5~1.0mm, without damage or deformation; S1.2 Component Pretreatment: Cleaning: Mechanical grinding and special cleaning agent are used to thoroughly remove iron oxide scale, oil stains and old grease residue from the surface. The surface finish of the bearing mating surface is ≤Ra0.8~1.2μm, with no attachments that may affect assembly accuracy. Activation and lubrication: Lightly grind and activate the gear shaft journal and bearing inner hole, and evenly apply assembly lubricating oil with a viscosity grade of 20~45, with an oil film thickness of ≤0.03mm, to ensure smooth assembly without jamming; Defect investigation: Inspect all components one by one to ensure there are no quality hazards such as cracks, deformation, or thread damage, and that bolts, washers, and auxiliary parts are of the correct specifications.

3. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: Preparation of tools and auxiliary materials as described in S1.3: Core tools: coaxiality gauge (range 0~300mm, accuracy 0.01mm), torque wrench (range 0~600N・m), bearing clearance gauge (range 0~0.5mm, accuracy 0.001mm), laser level (accuracy 0.02mm / m), special lifting fixtures (load capacity ≥100kg), dial indicator (accuracy 0.001mm), pressure gauge (range 0~1.0MPa, accuracy 0.01MPa); Supporting materials: high-temperature resistant grease (temperature resistance ≥180℃, dropping point ≥220℃), oil-resistant sealant, rust inhibitor, adjustable positioning pins (diameter 15~22mm), adjusting shims (thickness 0.1~0.5mm), anti-loosening washers, and dust-free wiping cloth.

4. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The S2.1D enclosure reference calibration: Horizontal fixation: Place the D box body stably on the horizontal assembly platform. The platform levelness error is ≤0.02~0.04mm / m. Level it with no more than 3 shims to ensure that the box body mounting surface is flat, stable and without shaking. Verticality calibration: Use a laser level to check the verticality of the mounting surface of the cabinet. The deviation should be ≤0.03~0.08mm / m. If the deviation exceeds the standard, adjust the position of the shims or grind the mating surface of the cabinet until the standard is met. Coaxiality test: Use a coaxiality test gauge to test the coaxiality of the bearing housing mounting holes at both ends of the housing. The allowable deviation is ≤0.04~0.09mm. If the deviation exceeds the standard, grind the inner wall of the bearing housing mounting holes to correct it and ensure accurate installation reference. S2.2 bearing housing precisely fixed: Adhesive application and positioning: Apply 0.1~0.3mm thick oil-resistant sealant evenly to the mating surface of the bearing housing and the housing. After hoisting the bearing housing, calibrate its center to be coaxial with the center hole of the housing. The deviation should be ≤0.03~0.07mm. Positioning pin fixing: Insert 6 to 8 adjustable positioning pins evenly distributed around the circumference, with an insertion depth of ≥35 to 45 mm and a fitting clearance of 0.01 to 0.04 mm to prevent assembly displacement; Cross-locking: Use a torque wrench to tighten the fixing bolts in a cross-symmetrical manner step by step. The torque should be controlled between 180 and 250 N·m. After tightening, use a feeler gauge to check that the fit gap is ≤0.03 to 0.06 mm to ensure a tight fit.

5. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The S3.1 middle double-row cylindrical roller bearing is installed as follows: Grease application and assembly: Apply high-temperature resistant grease evenly to the inner hole of the bearing housing and the outer surface of the bearing, with an oil film thickness of 0.03~0.06mm, and slowly press it into the preset middle position to avoid damaging the bearing by forced impact; Clearance adjustment: Use a bearing clearance tester to check the radial clearance and control it within 0.02~0.06mm. If it does not meet the standard, replace the adjusting shims (0.1~0.5mm) to correct it and ensure that the radial load capacity meets the standard. Fit verification: Observe the fit between the bearing end face and the shaft shoulder to ensure there is no gap or wobble and the fit is tight enough to meet the requirements.

6. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The tapered roller bearings on both sides of S3.2 are installed as follows: Symmetrical assembly: Tapered roller bearings are symmetrically press-fitted on both sides of the cylindrical roller bearing, and the position is adjusted to control the axial movement of the gear shaft within 0.03~0.08mm to ensure reasonable axial clearance; Load distribution optimization: The clearance of the tapered roller bearing is precisely controlled (0.01~0.04mm) by a bearing clearance detector to achieve scientific load distribution—the cylindrical roller bearing bears 70%~80% of the radial load, and the tapered roller bearings on both sides each bear all the axial load and 10%~15% of the radial load, avoiding overload failure of a single bearing; Coaxiality verification: Use a dial indicator to check that the overall coaxiality of the bearing assembly's inner bore is ≤0.03~0.07mm, and the circular runout of the bearing end face is ≤0.02~0.05mm, to ensure smooth operation without off-center load.

7. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The S4.1 gear shaft is precisely assembled: Smooth insertion: Slowly insert the pre-treated gear shaft into the inner hole of the bearing assembly, ensuring that the keyway and the inner ring positioning groove of the bearing are precisely aligned (deviation ≤0.03~0.06mm). There should be no forced impact or prying operation throughout the process to avoid damage to the journal and the inner hole of the bearing. Position calibration: Use a dial indicator to check the parallelism error between the gear end face and the housing reference surface. The error should be ≤0.03~0.06mm / m. Adjust the gear meshing clearance to 0.15~0.35mm to ensure smooth transmission without impact. Interchangeability Guarantee: The spare gear shaft is pre-processed according to the parameters of the existing components throughout the entire process. The journal size and keyway position are consistent with the key parameters. When interchangeable and assembled, the coaxiality deviation is ≤0.04~0.08mm, and no additional processing is required. The gear shaft and bearing assembly are matched and numbered one-to-one to facilitate quick identification and adaptation in the future.

8. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The S4.2 fuel supply system installation and calibration: Oil pipe positioning: Fix the new oil supply pipe at the preset position of the bearing housing end cover to ensure that the outlet is accurately aligned with the lubrication channel of the bearing assembly. The distance between the outlet and the bearing end face is 3~8mm to ensure that the lubricating oil is accurately sprayed to the contact surface between the rolling elements and the raceway. Sealing test: Introduce 0.3~0.6MPa compressed air into the oil supply system, maintain the pressure for 5~10 minutes, and observe that there is no leakage at the oil pipe interface and end cap, and the pressure does not drop significantly, which is considered qualified; Vibration-resistant fixing: Use special clips to firmly fix the oil pipes to prevent them from shifting or falling off due to vibration during unit operation.

9. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The S5.1 graded locking and fixing: End cap bolt tightening: Use a cross-symmetrical step-by-step tightening method to tighten the gear shaft end cap bolts, with the torque controlled at 80~120N・m to avoid local stress concentration that could cause end cap deformation; Bearing housing reinforcement and locking: Check the torque of the bearing housing fixing bolts to ensure that it is maintained at 180~250N・m; add anti-loosening washers or spot weld anti-loosening to all exposed bolts (2~3 weld points, weld point diameter ≤3mm) to prevent bolts from loosening during high-speed operation; S5.2 Static Precision Inspection: Core precision testing: The overall coaxiality of the gear shaft and the center hole of the housing is ≤0.04~0.09mm; the radial runout of the gear shaft is ≤0.02~0.05mm; the axial movement is ≤0.03~0.08mm; the coaxiality of the bearing assembly inner hole is ≤0.03~0.07mm. Fitting gap inspection: The fitting gap between the bearing housing and the housing is ≤0.03~0.06mm, and the positioning deviation of the oil supply pipe is ≤0.5~1.0mm, to ensure accurate positioning of each component and smooth lubrication path; S5.3 Dynamic Trial Operation Verification: No-load test: Start the D-box for no-load test run, gradually increase the speed from 500~800r / min to the rated speed of 1500~2000r / min, and continue for 30~60 minutes. The unit should have no abnormal vibration (vibration value ≤2.0~3.0mm / s), no abnormal noise, and the bearing temperature ≤70℃. Load test: After rolling 6.0~10.0mm steel and running continuously for 20~40 hours, the bearing temperature is ≤70~85℃, the gear meshing is smooth and without impact, the oil supply system has no leakage, the bearing assembly has no wear noise, and the equivalent load of the tapered roller bearing does not exceed 50% of the original design.

10. The method for installing and calibrating the D-box of a reducing sizing unit according to claim 1, characterized in that: The S6.1 all-around protection treatment: Rust prevention: Apply rust inhibitor evenly to the exposed surfaces of the gear shaft end, bearing housing end cover, and oil pipe interface to form a protective film and prevent air and moisture from corroding and rusting; Dustproof: The input / output terminals of the D box are fully covered with a special protective cover to prevent dust and impurities from entering the interior and affecting the operation of the components; Labeling: Mark the installation date, component matching number, and operator information in a prominent position on box D for easy traceability and maintenance; Complete S6.2 file retained: Record content: Record in detail all key information including core component parameters, assembly clearance, bolt torque, bearing clearance adjustment data, static test results, and trial operation status; Archiving requirements: Establish dual electronic and paper archives, clarify the interchangeability parameter standards of components, provide accurate basis for subsequent maintenance and component replacement, and improve maintenance efficiency.