Intelligent feeding and vibration suppression based roller mill device

Abstract

This utility model discloses a vertical roller mill device based on intelligent feeding and vibration suppression, belonging to the technical field of vertical roller mills, and solving the technical problem of excessive vibration caused by uneven material distribution in traditional equipment. A weighing sensor is installed directly below the discharge chute; a laser rangefinder vertically aligned with the center of the grinding disc is installed at the center of the inspection door on the top of the grinding disc cover; a material moisture detector is installed through the side wall of the discharge straight pipe section, with its sensing probe extending to the centerline of the pipe; three sets of vibration sensors are arranged in an axial chain structure in the transmission device. The first vibration sensor is fixed to the side wall of the flange at the output end of the transmission motor via a flange seat; the second vibration sensor is embedded in the center of the inspection cover on the top of the reducer; and the third vibration sensor is connected to the radial detection hole of the grinding disc main shaft bearing seat via an L-shaped angle bracket. This device, through the coordinated layout of multiple sensor sources, achieves real-time monitoring of material flow rate, material layer thickness, and equipment vibration, and is mainly used in the cement and mineral powder preparation fields to improve grinding efficiency.

Description

Technical Field

[0001] This utility model relates to the field of vertical roller mill technology. More specifically, this utility model relates to a vertical mill device based on intelligent feeding and vibration suppression. Background Technology

[0002] In the operation of a vertical roller mill (vertical mill), the uniformity of material feeding directly affects the stability of the equipment. Traditional devices rely on manual experience or simple feedback loops (such as a single level gauge) to adjust the feed rate, making it difficult to accurately sense and control the actual distribution of the material layer on the grinding disc. This can easily lead to excessively thick or thin material in local areas of the grinding disc, causing significant fluctuations in the pressure applied by the grinding rollers to the material layer.

[0003] The uneven distribution of materials and the resulting imbalance in grinding roller pressure are among the main causes of severe vibration in vertical mills. Excessive vibration not only accelerates the mechanical wear of transmission devices (including motors, reducers, and spindle bearings), but also significantly increases equipment failure rates and the risk of unplanned downtime. Simultaneously, inaccurate feeding and vibration control also lead to increased energy consumption during the grinding process.

[0004] In terms of vibration suppression, existing technologies mostly employ passive dampers or active vibration suppression devices with fixed parameters. Passive damping, due to its fixed inherent frequency, is ill-suited to effectively address the wide-frequency vibrations generated by vertical mills under varying operating conditions. Meanwhile, active vibration suppression devices with fixed parameters lack the ability to accurately sense real-time vibration conditions, making it impossible to dynamically adjust their suppression strategies and resulting in poor adaptability. The fundamental reason lies in the limitations of existing hardware monitoring systems: they lack sensor arrays capable of multi-dimensional, high-precision capture of spatial vibration characteristics at key locations (such as different nodes in the axial structure of the drive chain), and they also lack effective hardware and mechanical structures for reliable and synchronous monitoring of core material parameters (such as real-time material layer thickness and material flow rate). These hardware-level monitoring deficiencies make precise vibration suppression and feed coordination optimization difficult to achieve. Summary of the Invention

[0005] One object of this invention is to solve at least the aforementioned problems and / or defects, and to provide at least the advantages described below.

[0006] The purpose of this invention is to provide a vertical mill device based on intelligent feeding and vibration suppression, which addresses the problems of uneven feeding, excessive vibration, and high energy consumption in existing technologies. Through the coordinated layout of multiple source sensors, it achieves real-time monitoring of material flow rate, mill disc material layer thickness, and material characteristics. By deploying vibration sensors and accelerometers, it collects the mill vibration spectrum in real time, and through an active balancing device (electromagnetic actuator), it cancels out vibration energy in real time.

[0007] To achieve the objectives and other advantages of this invention, a vertical mill device based on intelligent feeding and vibration suppression is provided, comprising: a grinding disc, grinding rollers, and a transmission device, and further comprising:

[0008] The load cell is installed directly below the discharge chute.

[0009] The laser rangefinder is located at the center of the maintenance door on the top of the grinding disc cover, and the laser emission direction is perpendicular to the central area of ​​the grinding disc.

[0010] The material humidity detector is installed on the side wall of the straight discharge pipe section, and its sensing probe extends to the center line of the pipe.

[0011] Multiple vibration sensors are mounted on the axial chain structure of the transmission device, including a first vibration sensor, a second vibration sensor, and a third vibration sensor. The first vibration sensor is fixed to the side wall of the output flange of the transmission motor via a flange seat, and its sensing axis is parallel to the motor shaft. The second vibration sensor is installed in the center of the top inspection cover of the reducer housing via a threaded insert, and its sensing axis is vertically downward. The third vibration sensor is connected to the radial detection hole of the grinding disc spindle bearing seat via an L-shaped angle bracket, and its sensing axis is perpendicular to the spindle rotation axis.

[0012] Preferably, the vertical mill device based on intelligent feeding and vibration suppression further includes:

[0013] The first electromagnetic actuator is installed on the outer wall of the mill casing, and its output shaft points horizontally radially toward the center of the mill disc.

[0014] The second electromagnetic actuator is mounted on the side flange of the transmission device bearing seat via an L-shaped cast steel base, and its output shaft forms an angle of 15°±2° with the main shaft rotation axis.

[0015] Preferably, the vertical mill device based on intelligent feeding and vibration suppression further includes:

[0016] The accelerometer is screwed vertically into the center of the lateral boss of the transmission device bearing housing, and its sensing axis points horizontally towards the center line of the grinding disc spindle.

[0017] Preferably, the boss is a rectangular reinforcing structure, which is cast integrally with the bearing housing. The top surface of the boss is provided with a positioning pin hole, and the bottom of the accelerometer housing is provided with a positioning blind hole, which is connected to the positioning pin hole by a cylindrical pin transition fit.

[0018] Preferably, the flange seat is an annular structure with a flange, the inner diameter of which is interference-fitted with the outer diameter of the output flange of the drive motor, and the outer edge is provided with a sensor mounting screw hole, and the first vibration sensor is vertically locked into the screw hole by a double-ended bolt.

[0019] Preferably, the top inspection cover of the reducer housing has a countersunk mounting cavity at its center, the sensing end of the second vibration sensor is embedded in the cavity, and is radially locked by four sets of set screws evenly distributed around the circumference.

[0020] Preferably, the radial detection hole of the grinding disc spindle bearing housing is a through-hole, the sensing end of the third vibration sensor is positioned inside the hole by an elastic bushing, the vertical plate of the L-shaped bracket is welded to the housing of the third vibration sensor, and the horizontal plate is bolted to the end face of the grinding disc spindle bearing housing.

[0021] Preferably, the vertical plate of the L-shaped cast steel base has an elongated hole, the housing of the second electromagnetic actuator is slidably fitted into the elongated hole via an adjusting slider, and the tilt angle is fixed by a tightening bolt.

[0022] This utility model has at least the following beneficial effects:

[0023] First, this utility model, based on an intelligent feeding and vibration suppression vertical mill device, fundamentally improves the monitoring accuracy of the vertical mill's operating status through the coordinated layout of multiple source sensors. The weighing sensor is placed directly below the discharge chute, directly measuring the instantaneous material flow rate, avoiding the drift error (approximately ±3%) caused by material adhesion in traditional indirect measurements. A laser rangefinder is vertically aligned with the center of the mill disc, using high-frequency sampling (≥100Hz) to overcome mill disc rotation interference and achieve dynamic monitoring of the material layer thickness (accuracy ±0.5mm). Three sets of vibration sensors respectively capture key vibration characteristics of the axial structure of the transmission chain: the parallel arrangement of the motor output flange sidewall accurately monitors torsional vibration; the vertical mounting on the top of the reducer effectively identifies gear meshing impact; and the vertical layout of the radial detection holes in the main shaft bearing seat separates the eccentric vibration component. This hardware architecture achieves, for the first time, the synchronous and accurate perception of material distribution parameters and three-dimensional vibration characteristics, providing a reliable data foundation for collaborative control.

[0024] Secondly, this utility model's vertical mill device, based on intelligent feeding and vibration suppression, uses a first electromagnetic actuator to act horizontally and radially on the mill's inner casing, directly offsetting the lateral vibration energy of the grinding disc; the second electromagnetic actuator acts at a 15° angle on the transmission device bearing seat, specifically suppressing the combined vibration of the main shaft system (coupling components of axial and radial vibration). The unique angle design ensures precise matching of the vibration suppression force vector to the vibration transmission path, improving vibration energy attenuation efficiency compared to traditional vertical installation schemes. The L-shaped cast steel base, through rigid connection, avoids vibration suppression force transmission loss, and its structural strength can withstand transient impact loads exceeding 2000N.

[0025] Third, in this utility model, the accelerometer in the vertical mill device based on intelligent feeding and vibration suppression is horizontally screwed into the center of the lateral boss of the bearing housing, with its sensing axis collinear with the mill disc spindle. This arrangement directly captures the axial micro-displacement of the bearing housing under grinding pressure (range ±5g, resolution 0.001g), overcoming the data distortion caused by structural deformation in traditional shell-mounted installations. Actual measurements show that the vibration spectrum signal-to-noise ratio acquired at this location is 15dB higher than that of conventional measuring points, providing a sensitive characteristic for early bearing fault diagnosis.

[0026] Fourth, the integrally cast rectangular boss in the vertical mill device based on intelligent feeding and vibration suppression eliminates the resonance risk of traditional welded supports. Its natural frequency (>3000Hz) far exceeds the vibration frequency range of the vertical mill (10-200Hz). The transition fit (tolerance H7 / g6) between the positioning pin hole and the blind hole of the accelerometer ensures that the installation repeatability is ≤0.02mm, avoiding measurement reference offset due to disassembly and assembly. This structure allows the sensor to maintain stable contact under 2.5g vibration environment, extending its lifespan.

[0027] Fifth, in this utility model, the annular flange seat and the motor output end of the vertical mill device based on intelligent feeding and vibration suppression have an interference fit (interference amount 0.05-0.08mm), eliminating the fretting wear of traditional bolted connections under alternating torque. The double-headed bolt locking structure provides uniform preload, ensuring that the first vibration sensor maintains its fit even when the motor surface temperature is 120℃, and the fundamental frequency vibration measurement error is controlled within ±5%.

[0028] Sixth, in this utility model's vertical mill device based on intelligent feeding and vibration suppression, the countersunk mounting cavity completely embeds the second vibration sensor into the reducer top cover, isolating it from external dust corrosion. Four sets of radial set screws (uniformly distributed at 90° angles) achieve 360° uniform locking, avoiding uneven load caused by single-point fixing. This structure reduces the sensor's annual failure rate to below 0.5 times under reducer oil temperature of 90℃ and vibration of 4g.

[0029] Seventh, in this utility model, the elastic bushing (Shore hardness 50A) of the vertical mill device based on intelligent feeding and vibration suppression buffers the impact of spindle impact on the third vibration sensor, protecting the core sensitive element. The through-hole design ensures that the sensing end is only 15 mm away from the outer ring of the bearing, accurately capturing high-frequency shock waves (>5kHz) caused by raceway damage. The vertical plate welding of the L-shaped bracket and the horizontal plate bolt connection balance installation rigidity and maintenance convenience.

[0030] Eighth, this utility model utilizes a combination of an elongated hole (length tolerance ±0.1mm) and an adjusting slider in a vertical mill device based on intelligent feeding and vibration suppression to achieve fine-tuning of the tilt angle of the second electromagnetic actuator within the range of 13°-17°. The tightening bolts (pre-tightening torque 80 N·m) ensure stability of the vibration suppression force direction after locking, eliminating the risk of loosening. This structure allows the vibration suppression system to adapt to changes in the spindle's dynamic characteristics under different wear conditions, maintaining a vibration suppression efficiency >85%.

[0031] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0032] Figure 1 This is a structural schematic diagram of a specific embodiment of the present invention. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0034] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0035] It should be noted that in the description of this utility model, the terms "horizontal", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0036] It should be noted that, unless otherwise specified, the control methods in the following technical solutions are conventional methods, and the equipment structures, unless otherwise specified, can be obtained commercially.

[0037] like Figure 1 This utility model provides a vertical mill device based on intelligent feeding and vibration suppression, including: a grinding disc 1, a grinding roller 2, a transmission device 3, and further including:

[0038] Weighing sensor 4 is installed directly below the discharge chute 5;

[0039] The laser rangefinder 6 is located at the center of the maintenance door on the top of the grinding disc cover, and the laser emission direction is perpendicular to the central area of ​​the grinding disc 1.

[0040] The material humidity detector 7 is installed on the side wall of the discharge straight pipe section, and its sensing probe extends to the center line of the pipe.

[0041] Multiple vibration sensors are mounted on the axial chain structure of the transmission device 3, including a first vibration sensor 8, a second vibration sensor 9, and a third vibration sensor 10. The first vibration sensor 8 is fixed to the side wall of the output flange of the transmission motor via a flange seat, and its sensing axis is parallel to the motor shaft. The second vibration sensor 9 is installed in the center of the top inspection cover of the reducer housing via a threaded insert, and its sensing axis is vertically downward. The third vibration sensor 10 is connected to the radial detection hole of the grinding disc spindle bearing seat via an L-shaped angle bracket, and its sensing axis is perpendicular to the spindle rotation axis.

[0042] In the above technical solution, the weighing sensor 4 can be a resistance strain gauge sensor with a range of 0-5 tons, installed approximately 300 mm directly below the discharge chute 5, and fixed to the support frame via a flange. Its operation involves real-time acquisition of material weight pulse signals, which are then converted into 4-20mA current signals by a transmitter and transmitted to the PLC. The laser rangefinder 6 can use a 905 nm wavelength semiconductor laser with a maximum range of 1.5 m and an accuracy of ±1 mm. It is installed at the center of the inspection door on the top of the grinding disc cover and fixed via a universal adjustment bracket. The angle between the laser emission direction and the normal to the plane of the grinding disc 1 is ≤±2°. The material moisture detector 7 can be a microwave sensor with a frequency of 10 GHz. The probe is inserted into a Φ50 mm detection hole on the side wall of the discharge straight pipe section, extending to within ±5 mm of the pipe centerline. The first vibration sensor 8 can be an IEPE accelerometer with a range of ±50 g, fixed to the side wall of the output flange of the drive motor via an annular flange seat. The flange seat inner diameter and motor flange outer diameter have a fit tolerance of H7 / p6. The sensor is vertically locked with M8 double-ended bolts, and the parallelism between the sensing axis and the motor shaft is ≤0.1 mm. The second vibration sensor 9 can be a similar sensor and is installed in the countersunk cavity at the center of the inspection cover on the top of the reducer housing. The cavity depth is 15 mm, and it is radially locked by four sets of circumferentially distributed M5 set screws. The vertical downward deflection angle of the sensing axis is ≤0.5°. The third vibration sensor 10 can be a similar sensor and is connected to the grinding disc spindle bearing seat via an L-shaped bracket (material Q235B). The vertical plate of the bracket is welded to the sensor housing, and the horizontal plate is fixed to the bearing seat end face by four sets of M10 bolts. The sensor sensing end is positioned in the Φ12H7 radial detection hole through a polyurethane elastic bushing, and the orthogonality between the sensing axis and the spindle rotation axis is ≤0.05 mm. All sensor cables are protected by corrugated metal conduits (material 304, diameter Φ8 mm, bending radius >100 mm). The corrugated conduits have a bending radius ≥100 mm and a temperature resistance range of -40℃ to +120℃, conforming to GB / T 12777 standard. The corrugated conduits are laid along the equipment brackets and secured with stainless steel clamps (spacing ≤300 mm). A 2 mm thick silicone buffer pad is placed between the clamps and the corrugated conduit to prevent vibration and wear. When passing through walls or metal components, a metal sheath (inner diameter Φ10 mm) must be installed, and both ends of the sheath are sealed with sealant (silicone sealant, conforming to GB / T 14683 standard). When cables pass through high-temperature areas (such as near motors, where the temperature >80℃), a layer of fiberglass insulating tape (5 mm thick, temperature resistance ≥500℃) is wrapped around the corrugated conduit and secured with stainless steel cable ties (spacing ≤150 mm). The cable ends are connected using waterproof aviation plugs (compliant with GJB598B standard). The plug housing and the corrugated tube are connected via a grounding terminal (cross-sectional area ≥ 4 mm²). 2 Reliable grounding with a grounding resistance ≤ 4Ω. The cable shielding layer is grounded at one end and left floating at the other end to avoid forming a grounding loop.

[0043] The mounting base for the weighing sensor 4 can be made of Q345 steel plate (20 mm thick), with a flatness ≤0.1 mm / m. The access door for the laser rangefinder 6 has an opening size of 200×200 mm, and the door panel is fitted with a 5 mm thick tempered glass window. The inner wall of the detection hole for the material moisture detector 7 is lined with a PTFE wear-resistant sleeve with a wall thickness of 3 mm. The surface roughness of the mounting surfaces for the three vibration sensors is Ra≤3.2 μm, and the tightening torque of each bolt is controlled according to ISO 16047 standard: M8 bolt 12 N·m, M10 bolt 24 N·m, and M5 bolt 2.5 N·m.

[0044] This implementation method solves the measurement distortion problem caused by installation deviations in traditional vertical mills by precisely defining sensor selection parameters, installation positions, and structural fit. The coordinated layout of the weighing sensor and laser rangefinder can provide real-time feedback on the material distribution status, the spatial arrangement of the triaxial vibration sensor can completely collect the mill vibration spectrum, and the sealed structure of the humidity detector can prevent dust intrusion. Overall, it improves the reliability of measurement data and provides an accurate input benchmark for subsequent control algorithms.

[0045] In another technical solution, the vertical mill device based on intelligent feeding and vibration suppression also includes:

[0046] The first electromagnetic actuator 11 is installed on the outer wall of the mill housing, and its output shaft points horizontally radially toward the center of the mill disc.

[0047] The second electromagnetic actuator 12 is mounted on the side flange of the bearing seat of the transmission device 3 via an L-shaped cast steel base, and its output shaft forms an angle of 15°±2° with the rotation axis of the main shaft.

[0048] In the above technical solution, the first electromagnetic actuator 11 can be an electromagnetic linear actuator with a rated output of 5 kN. Its base is made of Q235B steel plate (20 mm thick) welded to the outer wall of the mill casing 14. The installation position is within ±50 mm of the geometric center height of the mill casing 14. The output shaft points horizontally radially toward the center of the grinding disc 1. The vertical distance from the upper surface of the base to the center of the grinding disc is 1200 ± 10 mm. The coaxiality tolerance between the output shaft and the center axis of the grinding disc is ensured to be ≤ Φ0.5 mm by measuring and positioning with a total station. The welding between the base and the casing 14 adopts a bevel weld with a weld leg height of 8 mm, which conforms to the gas shielded welding process specification of GB / T 985.1. Before welding, the welding surface needs to be derusted (surface roughness Ra≤25 μm). After welding, non-destructive testing (UT testing, Level II qualified) is performed. During operation, the electromagnetic actuator receives a 0-10 V control signal from the PLC, generating an electromagnetic force opposite in phase to the vibration, which is transmitted to the main structure of the mill through the base. The second electromagnetic actuator 12 can be a similar type of actuator, installed via an L-shaped cast steel base (material ZG270-500). A 150×30 mm oblong hole is cut into the vertical plate of the base, with a C2 chamfer on the hole edge. The adjusting slider is made of 45 steel with a tempered finish (hardness HRC28-32), and the sliding fit clearance with the oblong hole is 0.05-0.1 mm. The horizontal plate of the base is fixed to the side flange of the transmission device bearing seat by four sets of M16 bolts (performance grade 8.8), and the mating surfaces are coated with molybdenum disulfide grease. The angle between the output shaft and the rotation axis of the mill spindle is set to 15°±2°. After positioning by rotating the adjusting slider, the angle is locked by M12 tightening bolts (tightening torque 78 N·m). After assembly, the static load test shows that it can withstand a radial force of 2000 N without displacement. Dynamic calibration is required after installation: With the mill running under no-load, a 10-100Hz sweep frequency signal (amplitude ±3V) is input to the electromagnetic actuator, and the vibration response of the transmission device bearing housing is detected using accelerometer 13. Test data shows that at the 50Hz main vibration frequency, the vibration acceleration reduction meets design expectations. Structural strength, analyzed by ANSYS transient dynamics, shows that under 0-2000 N alternating load, the maximum stress of the L-shaped base is <120 MPa, with a safety factor >2.5. All fasteners are secured using a combination of spring washers as per GB / T6184 standards.

[0049] This implementation ensures the effective transmission of vibration suppression force by precisely defining the spatial orientation and structural parameters of the electromagnetic actuators. The horizontal radial layout of the first electromagnetic actuator 11 directly counteracts the lateral vibration of the grinding disc, while the 15° tilt of the second electromagnetic actuator 12 simultaneously suppresses both radial and axial vibration components. The elongated hole design of the L-shaped base provides fine-tuning capability, solving the problem of accumulated errors during on-site installation. The overall structure meets the reliability requirements under strong vibration conditions of the vertical mill, providing a stable execution basis for active vibration control. The materials used are as follows: Q235B conforms to GB / T 700, and ZG270-500 conforms to GB / T 11352.45; the steel processing technology refers to GB / T 3077; the tolerance standards are: coaxiality according to GB / T 1184-K grade, and angular tolerance according to GB / T 11334-2005; the test methods are: frequency sweep test according to GB / T 2423.10 vibration test standard, and stress analysis according to JB / T 5926; the control principle is: the electromagnetic actuator drive technology is existing technology (see "Active Vibration Control Technology and Application", Machinery Industry Press, 2018).

[0050] In another technical solution, the vertical mill device based on intelligent feeding and vibration suppression also includes:

[0051] Accelerometer 13 is screwed vertically into the center of the lateral boss of the bearing seat of transmission device 3, and its sensing axis is horizontally pointed to the center line of the grinding disc spindle.

[0052] In the above technical solution, the accelerometer 13 can be an IEPE type triaxial accelerometer sensor with a range of ±500g and a frequency response of 0.5-5000 Hz. It is vertically screwed into the center of the lateral boss of the transmission device bearing housing via an M10×1 fine thread, with a thread engagement length ≥12 mm. The boss is a rectangular reinforced structure (dimensions 120×80×25 mm), cast integrally with the bearing housing body, and made of the same material as the bearing housing (e.g., ZG270-500). A Φ6H7 locating pin hole with a depth of 8 mm is provided at the center of the top surface of the boss; a Φ6m6 locating blind hole with a depth of 10 mm is machined on the bottom of the accelerometer housing. During assembly, a Φ6×20 mm cylindrical pin (material GCr15) is coated with lithium-based grease and inserted into the pin hole to achieve a transition fit (tolerance H7 / m6). In the specific implementation, the tolerance of the inner diameter of the locating pin hole is explicitly stated to be H7 (e.g., Φ20H7, tolerance range is +0.021 / 0)), and the tolerance of the inner diameter of the blind hole is m6 (e.g., Φ20m6, tolerance range is +0.033 / +0.017)). During processing, high-precision CNC machining equipment is used to ensure that dimensional accuracy is controlled within the tolerance range. During assembly, a press is used to slowly press the locating pin into the pin hole and blind hole. The interference fit ensures that the accelerometer is firmly installed and does not shift under the strong vibration environment of the vertical mill, ensuring the accuracy and reliability of vibration monitoring data. Simultaneously, the assembled components are sampled and inspected. By measuring the fit clearance between the locating pin and the pin hole and blind hole, it is verified whether it meets the H7 / m6 tolerance standard, ensuring product quality consistency. The accelerometer's sensing axis is horizontally aligned with the center line of the grinding disc spindle, with a coaxiality tolerance ≤ Φ0.1mm. The tightening torque is set to 35 N·m ± 10%, tightened in two stages using a preset torque wrench (initial tightening at 20 N·m, followed by a final tightening at 35 N·m). Functional testing employs the impact method: a 5 N·s impact force is applied to the end face of the grinding disc spindle, and the decaying vibration waveform is collected using the accelerometer. Test results show a signal-to-noise ratio ≥ 60dB within the 100-800Hz frequency band. Structural vibration resistance analysis using ANSYS shows a maximum resonant amplitude < 0.002 mm within the 0-1000 Hz sweep frequency range. Shielded twisted-pair cable (0.75mm² cross-sectional area) can be used for the sensor cable, protected by a Φ10mm metal flexible conduit, with both ends secured with PG9 cable connectors. The roughness Ra of the boss mounting surface is ≤ 1.6μm, and the flatness is ≤ 0.05 mm. During regular maintenance, long-term positioning accuracy can be ensured by measuring the clearance between the locating pin hole and the blind hole (using a Φ6mm plug gauge; if the clearance is >0.02 mm, the pin needs to be replaced). The operating temperature range is -20℃ to +85℃, meeting the environmental testing requirements of GB / T 2423.1 / 2.The materials used are as follows: ZG270-500 conforms to GB / T 11352, and GCr15 conforms to GB / T18254; tolerance standards: H7 / m6 fit conforms to GB / T 1800.1, and flatness conforms to GB / T 1184-G grade; test methods: hammer impact method conforms to ISO 7626 vibration test standard, and environmental test conforms to GB / T2423 series; dynamic analysis: harmonic response analysis parameters are set according to JB / T 5926-2018 mechanical vibration standard.

[0053] This implementation method solves the displacement drift problem of the accelerometer under strong vibration environments through a dual fixing mechanism of locating pins and threads. The integrated cast structure of the boss avoids the stress concentration risk of traditional welded bases, and hammer impact tests show that it can accurately capture broadband vibration signals. The cylindrical pin transition fit design ensures a positioning repeatability accuracy of ≤0.01 mm during disassembly and maintenance, guaranteeing the consistency of measurement data. The overall structure meets the requirements of high temperature, high humidity, and strong vibration conditions of the vertical mill's transmission parts.

[0054] In another technical solution, the boss is a rectangular reinforced structure, which is cast as one piece with the bearing housing. The top surface of the boss is provided with a positioning pin hole, and the bottom of the accelerometer 13 housing is provided with a positioning blind hole, which is connected to the positioning pin hole by a cylindrical pin transition fit.

[0055] In the above technical solution, the boss is a rectangular reinforcing structure of 120×80×25 mm, cast integrally with the bearing housing body of the transmission device. The material can be ZG270-500 cast steel, conforming to GB / T 11352 standard. A Φ6H7 (+0.012 / 0) locating pin hole is provided at the center of the top surface of the boss, with a hole depth of 8±0.1 mm. The hole diameter tolerance is machined to IT7 grade precision according to GB / T 1800.4-1999. The parallelism tolerance between the axis of the locating pin hole and the axis of the bearing housing spindle mounting hole is ≤0.03 mm / 100 mm. After casting, it undergoes annealing treatment at 620℃±10℃ to eliminate internal stress, and the Brinell hardness is controlled within the range of HB180-200. A Φ6m6 (+0.008 / +0.002) locating blind hole with a depth of 10±0.1 mm is machined on the bottom of the accelerometer 13 housing. A Φ6×20 mm cylindrical pin (material GCr15 bearing steel, conforming to GB / T 18254) with a surface hardening hardness of HRC58-62 can be selected. During assembly, the cylindrical pin is coated with lithium-based grease (NLGI No. 2) and then pressed into the locating pin hole to form an H7 / m6 transition fit (interference 0.002-0.018 mm). The clearance between the blind hole and the cylindrical pin should be ≤0.01 mm, and after assembly, the top of the cylindrical pin should be 2±0.2 mm lower than the bottom surface of the blind hole. The surface roughness Ra of the mating surface should be ≤0.8 μm, and the cylindricity tolerance should be ≤0.003 mm. During periodic maintenance, a Φ6 mm standard plug gauge should be used to check the fit: the spur end (Φ6.00 mm) should be able to be inserted without resistance, and the insertion depth of the no-go end (Φ6.02 mm) should be ≤1 mm. Replace the cylindrical pin when the clearance is >0.02 mm. The positioning repeatability after disassembly and reinstallation was tested using a coordinate measuring machine (CMM), with a positional deviation ≤0.015 mm. Under operating conditions, vibration signals from 0-1000Hz were collected using a spectrum analyzer, and the measurement noise caused by the positioning structure was <0.05 g RMS. The process standards were as follows: annealing process according to GB / T 16923-2008, hardness testing according to GB / T 231.1; tolerance standards: H7 / m6 fit conforms to GB / T 1801-2009, positional tolerance according to GB / T13319; testing methods: plug gauge testing according to GB / T 1957-2006, CMM testing according to ISO 10360-2; noise testing: vibration noise testing according to ISO 10816-3 mechanical vibration standard.

[0056] This implementation avoids the risk of bolt loosening inherent in split mounting brackets through a cast-in-one boss and precision transition fit design. The H7 / m6 fit between the locating pin hole and the blind hole ensures the accelerometer's positional stability under strong vibration environments, while the annealing process eliminates the impact of casting stress on positioning accuracy. The plug gauge inspection method quantitatively assesses the wear condition of the fit, and after maintenance, the positional deviation is controlled within allowable limits, ensuring the long-term reliability of vibration monitoring data.

[0057] In another technical solution, the flange seat is an annular structure with a flange, and its inner diameter is interference-fitted with the outer diameter of the output flange of the drive motor. The outer edge is provided with a sensor mounting screw hole, and the first vibration sensor is vertically locked into the screw hole by a double-ended bolt.

[0058] In the above technical solution, the flange seat can be made of 45 steel with heat treatment (hardness HRC28-32), with an annular flange structure, an outer diameter of 120±0.5 mm, and an inner diameter designed according to the outer diameter of the output flange of the drive motor. If the outer diameter of the motor flange is 100h6 (-0.022 / 0), then the inner diameter of the flange seat is machined to 100p6 (+0.037 / +0.022), forming an interference fit (interference amount 0.022-0.059 mm). The flange thickness is 20±0.2 mm, the radial width is 30 mm, and there are 6 M8 threaded holes (hole depth 15 mm) evenly distributed around the circumference, with a thread accuracy of 6H grade. During installation, the flange is installed onto the motor flange after being heated to 150℃±10℃ in an oil bath, and then tightened after cooling. The first vibration sensor 8 can be an IEPE accelerometer with an M8×1 mounting thread, which is vertically locked with double-ended bolts (material 35CrMo, performance grade 10.9). The double-ended bolts should be screwed into the flange seat threaded hole to a depth ≥12 mm, with an exposed length of 10±1 mm. Tightening torque should be applied in two stages: an initial pre-tightening of 5 N·m and a final tightening of 12 N·m±10%, using a preset torque wrench. The parallelism between the sensor's sensing axis and the motor shaft should be ≤0.1 mm. Verification method: use a dial indicator to check the side of the sensor, manually rotate the motor shaft one revolution, and the radial runout should be ≤0.2 mm. Under operating conditions, tests should be conducted at the motor's rated speed of 1500 rpm: a 0-1000Hz spectrum should be collected using a vibration analyzer, and the base resonant frequency should be >800 Hz. ANSYS modal analysis indicates the flange seat's first natural frequency is 850Hz, avoiding the 25th harmonic of the power frequency (625 Hz). Temperature adaptability testing should be performed according to GB / T 2423.22: after 5 cycles from -25℃ to +80℃, the bolt pre-tightening force attenuation rate should be <5% (detected using an ultrasonic bolt stress meter). Protective measures: The flange seat surface is galvanized (thickness ≥ 8 μm), and the bolt threads are coated with molybdenum disulfide anti-seize agent. Material standards: 45 steel according to GB / T699, 35CrMo according to GB / T 3077; Tolerance fit: H7 / p6 conforms to GB / T1801-2009, threads according to GB / T197-2018; Test methods: Vibration test according to ISO 10816-3, temperature test according to GB / T 2423.22; Anti-loosening verification: Preload test according to GB / T 16823.3-2010.

[0059] This implementation method solves the loosening problem of traditional bolted connections under vibration environments through the dual protection of interference fit and torque control. The heated assembly process eliminates stress concentration caused by mechanical pressing, and the double-ended bolt connection facilitates sensor disassembly and maintenance. Modal analysis shows that the base's natural frequency is far from the main excitation frequency band, avoiding resonance amplification effects. Temperature cycling tests verify the structure's stability over a wide temperature range, ensuring the accuracy of vibration signal acquisition.

[0060] In another technical solution, the top inspection cover of the reducer housing has a countersunk mounting cavity at its center. The sensing end of the second vibration sensor is embedded in this cavity and radially locked by four sets of set screws evenly distributed around the circumference.

[0061] In the above technical solution, a cylindrical countersunk mounting cavity is machined at the center of the inspection cover on the top of the reducer housing. The cavity diameter can be set to 28±0.5 mm and the depth to 15±0.1 mm. The inner wall of the cavity is machined with an M30×1.5 fine thread (tolerance zone 6H), with a thread length of 12 mm. The flatness of the cavity bottom surface is ≤0.02 mm, and the parallelism with the upper surface of the inspection cover is ≤0.05 mm / 100 mm. The inspection cover material can be QT500-7 ductile iron, which is subjected to aging treatment after casting to eliminate stress. A Φ3 mm vent hole is drilled at the center of the bottom of the cavity to avoid air resistance during assembly. The second vibration sensor 9 can be a cylindrical shell structure (diameter 28h6(-0.013 / -0.029)). After the sensing end is embedded in the cavity, its top end is 2±0.3 mm below the upper surface of the inspection cover. Four sets of M5 set screw mounting holes are evenly distributed circumferentially, with a hole angle of 90°, a hole depth of 12 mm, and a thread accuracy of 6H grade. The set screw can be made of 35CrMo alloy steel (tensile strength ≥980MPa), with an 8mm thread length and a 60° taper at the tip. During assembly, first screw the sensor into the cavity until it contacts the bottom surface, then tighten the set screw in a crisscross sequence: initial pre-tightening torque 1.0 N·m, second final tightening torque 2.5 N·m ±10%. After assembly, use a laser collimator to check the sensor axis deviation: fix the collimator at the center of the grinding disc, adjust the position of the electromagnetic actuator so that the deviation between the laser beam and the output shaft axis is ≤0.5 mm, calibrate, temporarily fix the base with a locating pin (Φ8 mm), and then perform formal welding. The vertical downward deviation is ≤0.3°. Vibration testing is conducted on a dedicated test bench: input a 5-500 Hz sweep frequency signal (acceleration 2 g), and monitor the micro-displacement of the sensor housing using a laser displacement sensor. Data shows that at the 250Hz main vibration frequency, the maximum displacement is ≤0.02 mm. Temperature adaptability testing according to GB / T 2423.22: After 5 cycles from -20℃ to 80℃, the preload of the set screw decreases by <8% (measured using strain gauge method). Maintenance and disassembly only require loosening the set screw to remove the sensor without damage. Repeat installation positioning accuracy is ≤0.015 mm as measured by a coordinate measuring machine. Material standards: QT500-7 conforms to GB / T1348, 35CrMo conforms to GB / T 3077; Tolerance settings: Diameter fit H7 / h6 conforms to GB / T1800.1, flatness conforms to GB / T 1184; Test methods: Vibration test refers to ISO 10816-3, temperature test according to GB / T 2423.22; Testing equipment: Laser collimator accuracy 0.01 mm / m, coordinate measuring machine calibrated according to ISO10360.

[0062] This implementation uses a countersunk cavity to provide full circumferential protection for the second vibration sensor 9, effectively preventing dust and oil corrosion. The radial constraint mechanism of four sets of set screws overcomes the risk of loosening under high-frequency vibration of traditional threaded installations. The step-by-step tightening process ensures the perpendicularity of the sensor axis, keeping the vibration vector measurement error within the allowable range. The vent design eliminates the interference of air pressure changes in the sealed cavity on the measurement, and the overall structure meets the long-term stable monitoring requirements of the vertical mill reducer under high temperature and high humidity conditions.

[0063] In another technical solution, the radial detection hole of the grinding disc spindle bearing housing is a through-hole, and the sensing end of the third vibration sensor is positioned in the hole through an elastic bushing. The vertical plate of the L-shaped bracket is welded to the housing of the third vibration sensor, and the horizontal plate is bolted to the end face of the grinding disc spindle bearing housing.

[0064] In the above technical solution, the radial inspection hole of the grinding disc spindle bearing housing is a through-hole with a diameter of 12H7 (+0.018 / 0), a depth of 60±0.2 mm, and an inner wall roughness Ra≤1.6 μm. The orthogonality tolerance between the hole axis and the spindle rotation axis is ≤0.05 mm / 100 mm. The bearing housing material can be QT600-3 ductile iron, annealed at 560℃±10℃ after casting. The two ends of the hole are chamfered at C0.5 to prevent scratching the elastic bushing during assembly. The inspection hole is located at a 120° symmetrical distribution point in the bearing housing load area, 40±1 mm from the end face. The elastic bushing can be made of polyurethane material (Shore hardness 85A±5), with an outer diameter of 12.3±0.1 mm, forming a radial interference of 0.2-0.3 mm with the inspection hole. The bushing has an inner diameter of 8.0±0.05 mm and a length of 55 mm. A spiral oil groove (0.3 mm depth, 5 mm pitch) is formed on the inner wall. The third vibration sensor 10 has a sensing end diameter of 8h6 (-0.009 / -0.025), which forms a flexible support after being pressed into the bushing. During assembly, a special guide bushing tool is used, and the bushing is slowly pressed in with a pressure of 3-5 kN to avoid material shear damage. Nylon retaining rings (1.5 mm thick) are installed at both ends of the bushing to prevent axial movement. The L-shaped bracket can be made of Q355B steel plate (10 mm thick). The vertical plate is 50×40 mm in size and is joined to the housing of the third vibration sensor using a continuous fillet weld (weld leg height 4 mm). The horizontal plate is 60×50 mm in size and has four Φ11 mm through holes, the hole positions matching the threaded holes on the bearing seat end face. During installation, use M10×35 bolts (performance grade 8.8) for connection, with a tightening torque of 24 N·m ±10%, tightened in two stages: an initial tightening of 10 N·m and a final tightening of 24 N·m. After assembly, the orthogonality between the sensor sensing axis and the spindle rotation axis should be ≤0.1 mm. Material standards: QT600-3 conforms to GB / T 1348, and polyurethane hardness conforms to GB / T 531.1; tolerance settings: H7 hole tolerance conforms to GB / T 1800.1, and interference fit design refers to GB / T 5371; assembly process: press-fitting force control conforms to JB / T 5994, and welding conforms to GB / T 985.1; testing method: orthogonality testing is performed using a coordinate measuring machine, standard ISO10360-2.

[0065] This implementation effectively isolates the interference of high-frequency vibration on the measurement signal through the interference fit of the elastic bushing and flexible support. The through-hole structure facilitates installation guidance and wear detection, while the spiral oil groove design prevents the bushing from sticking to the sensor. The welding-bolt composite connection method of the L-shaped angle bracket balances structural rigidity and disassembly, and orthogonality control ensures the accuracy of radial vibration measurement. The overall structure exhibits stable monitoring performance in the oily and high-temperature environment of the vertical mill spindle bearing.

[0066] In another technical solution, an elongated hole is opened in the vertical plate of the L-shaped cast steel base, and the housing of the second electromagnetic actuator is slidably fitted into the elongated hole via an adjusting slider, and the tilt angle is fixed by a tightening bolt.

[0067] In the above technical solution, the L-shaped cast steel base can be made of ZG270-500 material, with a vertical plate thickness of 20±0.5 mm and a horizontal plate thickness of 25±0.5 mm. A 150×30 mm oblong hole is formed in the vertical plate, with a length tolerance of ±0.3 mm and a width tolerance of ±0.1 mm, and a C1.5 chamfer on the hole edge. The center line of the oblong hole is 80±0.5 mm from the bottom surface of the base and 45±0.5 mm from the side edge. Four Φ17 mm mounting holes are drilled in the horizontal plate, with the hole positions matching the threaded holes on the side flange face of the transmission device bearing seat, and a hole spacing tolerance of ±0.15 mm. After casting, the base is annealed at 620℃, sandblasted to remove rust, and the surface is galvanized with a thickness ≥15 microns. The adjusting slider can be made of 45 steel with heat treatment (hardness HRC28-32), with external dimensions of 148×28×40 mm and a sliding fit clearance of 0.08-0.12 mm with the oblong hole. A Φ20H7 (+0.021 / 0) through hole is machined at the center of the slider for mounting the housing of the second electromagnetic actuator 12. Guide grooves (2 mm deep, 5 mm wide) are milled on both sides of the slider, and brass guide strips (H62 material, 2 ± 0.05 mm thick) are embedded in the corresponding oblong holes. The guide strips and oblong holes are interference-fitted (interference 0.02-0.05 mm). An angle scale is engraved on the top surface of the slider, with a graduation of 1° and a range of ±10°. The tightening bolt uses an M12×1.25 fine thread (performance grade 10.9) and is screwed into the side threaded hole of the slider (20 mm deep). The bolt end is machined with a 60° conical surface to mate with the countersunk hole (60° ± 1° cone angle) on the back of the vertical plate of the base. The tightening torque is applied in two stages: an initial pre-tightening of 35 N·m and a final tightening of 78 N·m ± 5%. After assembly, the included angle of the output shaft is checked using an angle gauge (15°±2°), and the gap between the slider and the base is checked using a feeler gauge (≤0.05 mm). Dynamic testing input is 0-50Hz variable frequency vibration, monitored by a laser displacement sensor, with a maximum relative displacement of 0.15 mm. After temperature cycling testing (-20℃ to 80℃), a re-inspection is performed, and the angle deviation increment is ≤0.3°. Material standards: ZG270-500 conforms to GB / T 11352, H62 brass conforms to GB / T5231; tolerance settings: oblong hole tolerance is GB / T 1804-m grade, angle tolerance refers to GB / T 11334; testing methods: vibration test according to GB / T 2423.10, temperature test according to GB / T 2423.22; anti-loosening verification: torque control refers to GB / T16823.3-2010.

[0068] This implementation achieves stepless adjustment of the electromagnetic actuator's tilt angle through the precise fit between the elongated hole and the guide bar. The fine-pitch thread clamping mechanism generates sufficient locking force under a torque of 78 N·m, and the brass guide bar reduces the coefficient of sliding friction. The angle scale design facilitates rapid on-site positioning, and vibration and temperature tests have verified that this structure can meet the long-term vibration control requirements of the vertical mill's transmission components.

[0069] The third vibration sensor 10 is installed in the radial detection hole of the main shaft bearing housing, with its sensing axis perpendicular to the main shaft. This position is chosen based on the vibration mechanism of the vertical mill. During operation, radial eccentric vibration of the main shaft is one of the key factors leading to equipment failure and affecting grinding efficiency. The radial direction perpendicular to the main shaft can directly monitor the vibration signal generated by the radial offset of the main shaft caused by uneven material distribution, uneven wear of grinding rollers, etc. By monitoring parameters such as vibration acceleration and displacement in this direction, abnormal operating conditions of the main shaft can be detected in a timely manner. For example, when the radial vibration acceleration exceeds a set threshold (such as 3g), it indicates that there may be uneven gap between the grinding roller and the grinding disc, which needs to be adjusted in time. This installation position can provide the control system with key radial vibration information, and in conjunction with vibration monitoring data in other directions (such as the axial direction), it can achieve a comprehensive assessment and precise control of the overall vibration state of the vertical mill.

[0070] Weighing sensors are installed in the feeding pipeline to monitor material flow in real time. Their data provides direct basis for the fuzzy PID algorithm to adjust the feed rate, ensuring that the material supply matches the grinding capacity of the mill disc and reducing vibration caused by material fluctuations at the source. A laser rangefinder is vertically aligned with the center of the mill disc to measure the material layer thickness, which, together with the material flow data, reflects the dynamic balance of materials inside the vertical mill. A humidity detector is installed on the centerline of the pipeline to monitor material humidity. Changes in humidity affect material flowability and grinding characteristics, thus affecting vibration. Its data participates in the control system calculations, enabling multi-parameter coordinated control and improving the operational stability and grinding efficiency of the vertical mill. The close interconnected installation positions of all sensors form an organic monitoring network, sensing the operating status of the vertical mill from different dimensions and providing comprehensive and accurate data support for the control algorithm.

[0071] This invention employs multiple sensors (weighing sensor, laser rangefinder, and material moisture detector) to monitor material flow rate, grinding disc material layer thickness, and material characteristics in real time. Based on the widely used fuzzy PID algorithm (e.g., "Design of Motor Speed ​​Control System Based on Fuzzy PID Algorithm," Bai Panpan, Nie Wenyan, Journal of Xi'an University of Arts and Sciences (Natural Science Edition), Vol. 25, No. 4, October 2022), the feeder speed is dynamically adjusted to achieve optimal feeding rate and grinding roller pressure. Vibration sensors and accelerometers are deployed to collect the mill vibration spectrum in real time. An active balancing device (electromagnetic actuator) combined with widely used adaptive control algorithms (e.g., "Research on Energy Efficiency Optimization of Electrical Equipment Based on Adaptive Control Algorithm," Li Weiguo, Electrical Technology and Economy, 2024.09.20) is used to offset vibration energy in real time. Feeding and vibration control are integrated into a PLC and an industrial computer to achieve dual-variable collaborative optimization control.

[0072] Although the technical solution of this utility model has been disclosed above, it is not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A vertical mill device based on intelligent feeding and vibration suppression, mill disc, mill roller, transmission device, characterized in that, Also includes: The load cell is installed directly below the discharge chute. The laser rangefinder is located at the center of the maintenance door on the top of the grinding disc cover, and the laser emission direction is perpendicular to the central area of ​​the grinding disc. The material humidity detector is installed on the side wall of the straight discharge pipe section, and its sensing probe extends to the center line of the pipe. Multiple vibration sensors are mounted on the axial chain structure of the transmission device, including a first vibration sensor, a second vibration sensor, and a third vibration sensor. The first vibration sensor is fixed to the side wall of the output flange of the transmission motor via a flange seat, and its sensing axis is parallel to the motor shaft. The second vibration sensor is installed in the center of the top inspection cover of the reducer housing via a threaded insert, and its sensing axis is vertically downward. The third vibration sensor is connected to the radial detection hole of the grinding disc spindle bearing seat via an L-shaped angle bracket, and its sensing axis is perpendicular to the spindle rotation axis.

2. The smart feeding and vibration suppression based vertical mill device as claimed in claim 1, wherein, Also includes: The first electromagnetic actuator is installed on the outer wall of the mill casing, and its output shaft points horizontally radially toward the center of the mill disc. The second electromagnetic actuator is mounted on the side flange of the transmission device bearing seat via an L-shaped cast steel base, and its output shaft forms an angle of 15°±2° with the main shaft rotation axis.

3. The smart feeding and vibration suppression based vertical mill device as claimed in claim 1, wherein, Also includes: The accelerometer is screwed vertically into the center of the lateral boss of the transmission device bearing housing, and its sensing axis points horizontally towards the center line of the grinding disc spindle.

4. The vertical mill device based on intelligent feeding and vibration suppression as described in claim 3, characterized in that, The boss is a rectangular reinforced structure, which is cast as one piece with the bearing housing. The top surface of the boss is provided with a locating pin hole, and the bottom of the accelerometer housing is provided with a locating blind hole, which is connected to the locating pin hole by a cylindrical pin transition fit.

5. The vertical mill device based on intelligent feeding and vibration suppression as described in claim 1, characterized in that, The flange seat is an annular structure with a flange. Its inner diameter is interference-fitted with the outer diameter of the output flange of the drive motor. The outer edge is provided with sensor mounting screw holes. The first vibration sensor is vertically locked into the screw holes by double-ended bolts.

6. The vertical mill device based on intelligent feeding and vibration suppression as described in claim 1, characterized in that, The top inspection cover of the reducer housing has a countersunk mounting cavity in the center. The sensing end of the second vibration sensor is embedded in the cavity of the countersunk mounting cavity and is radially locked by four sets of set screws evenly distributed around the circumference.

7. The vertical mill device based on intelligent feeding and vibration suppression as described in claim 1, characterized in that, The radial detection hole of the grinding disc spindle bearing housing is a through-hole. The sensing end of the third vibration sensor is positioned inside the hole through an elastic bushing. The vertical plate of the L-shaped bracket is welded to the housing of the third vibration sensor, and the horizontal plate is bolted to the end face of the grinding disc spindle bearing housing.

8. The vertical mill device based on intelligent feeding and vibration suppression as described in claim 2, characterized in that, The vertical plate of the L-shaped cast steel base has an elongated hole. The housing of the second electromagnetic actuator is slidably fitted into the elongated hole via an adjusting slider, and the tilt angle is fixed by a tightening bolt.

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