Stress-optimized bearing system and method for manufacturing same

Abstract

The invention belongs to the technical field of ventilation and fan manufacturing, and discloses a stress-optimized bearing system and a manufacturing method thereof.The stress-optimized bearing system comprises a conical shaft core with a shaft core large-head end and a shaft core small-head end, and the diameter of the shaft core large-head end is larger than that of the shaft core small-head end; the bearing is matched with the conical shaft core, and an inner hole of the bearing is of a conical structure matched with the shaft core; a wear-resistant sheet is arranged at the small shaft core end of the conical shaft core; according to the bearing system, when the fan rotor operates, the gravity center of the rotor is located in the bearing and corresponds to the large head end area of the shaft core; the gravity center of the rotor is borne by the large end of the conical shaft core, and the inertia load of the small end of the conical shaft core is reduced through the weight reduction groove, so that the stress distribution of the bearing inner hole of the bearing is uniform, and the wear resistance of the wear-resistant sheet is improved; and continuous lubrication under the high-speed working condition is ensured, and the jamming fault is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ventilation and fan manufacturing, and in particular to a stress-optimized bearing system and a manufacturing method thereof. Background Art

[0002] In the field of ventilation equipment and fan manufacturing, traditional bearing systems generally have the following technical defects:

[0003] The traditional shaft core adopts a cylindrical design with equal diameter, resulting in a mismatch between the rotor's center of gravity and the bearing support point. During operation, stress is concentrated in the upper area of ​​the bearing inner bore, causing problems such as scratches on the shaft core surface, burning of the bearing inner bore, and wear-through of the wear-resistant plate, significantly shortening the service life. The rigid contact between the shaft core and the bearing is prone to radial runout and axial movement, causing fan vibration and excessive noise (>55dB(A)), which is especially serious under high-speed conditions. The existing clearance design between the bearing inner bore and the shaft core is unreasonable. The lubricating oil film is easily broken during high-speed operation, exacerbating the wear of the friction pair and even causing bearing seizure failure. Summary of the Invention

[0004] The main purpose of the present invention is to provide a stress-optimized bearing system and a manufacturing method thereof, aiming to solve the problem that the traditional shaft core adopts an equal-diameter cylindrical design, which leads to a mismatch between the center of gravity of the rotor and the bearing support point. During operation, the stress is concentrated in the upper area of ​​the bearing inner hole, causing problems such as scratches on the shaft core surface, burning of the bearing inner hole, and wear-through of the wear-resistant plate, which significantly shortens the service life. The rigid contact between the shaft core and the bearing is prone to radial runout and axial movement, causing fan vibration and excessive noise (>55dB(A)), which is especially serious under high-speed conditions. The existing gap design between the bearing inner hole and the shaft core is unreasonable. The lubricating oil film is easily broken during high-speed operation, which aggravates the wear of the friction pair and even causes the technical problem of bearing seizure failure.

[0005] In order to achieve the above-mentioned object of the invention, the first aspect of the present invention provides a stress-optimized bearing system and a manufacturing method thereof, comprising:

[0006] The tapered shaft core has a large shaft core end and a small shaft core end, wherein the diameter of the large shaft core end is larger than the diameter of the small shaft core end;

[0007] The bearing is matched with the tapered shaft core, and its inner hole is a tapered structure adapted to the shaft core;

[0008] The small end of the tapered shaft core is provided with a wear-resistant sheet;

[0009] The bearing system is configured so that when the wind turbine rotor is running, the center of gravity of the rotor is located inside the bearing and corresponds to the large end area of ​​the shaft core.

[0010] Furthermore, an axial step difference is formed between the large end of the shaft core and the inner hole of the bearing, and the size range of the axial step difference is 0.05-0.3 mm.

[0011] Furthermore, the surface of the wear-resistant sheet is provided with a diamond-like carbon coating, and the coating thickness is 2-5 μm.

[0012] Furthermore, the bearing is an oil-containing bearing, the taper angle α of the bearing inner hole is 0.5°-3°, and the taper angle β of the tapered shaft core satisfies β=α±0.2°.

[0013] Furthermore, it also includes a weight-reducing groove provided at the small end of the shaft core, and the depth of the weight-reducing groove is 10%-25% of the diameter of the shaft core.

[0014] The present invention also provides a method for manufacturing a stress-optimized bearing system, comprising:

[0015] Step S1: forming a tapered shaft core with a predetermined taper angle by precision turning;

[0016] Step S2: manufacturing an oil-containing bearing by a powder metallurgy process, and simultaneously forming a bearing inner hole that matches the taper of the shaft core;

[0017] Step S3: performing plasma spraying on the surface of the big end of the shaft core to form a wear-resistant layer;

[0018] Step S4: After the bearing is pressed into the middle tube of the bracket, dynamic balancing calibration is performed.

[0019] Furthermore, in step S3, the spraying parameters include:

[0020] The spraying distance is 80-120mm;

[0021] Plasma power is 30-45kW;

[0022] The powder feeding rate is 25-40g / min;

[0023] The substrate preheating temperature is 150-200℃.

[0024] Furthermore, the dynamic balance calibration adopts a double-surface correction method of the P1 surface and the P2 surface, and the correction position is located in the end surface of the large end of the shaft core and the weight-reducing groove area of ​​the small end of the shaft core.

[0025] Furthermore, when the rotation speed of the bearing system is ≥8000 rpm, the radial runout of the tapered shaft core is ≤0.02 mm, and the axial runout is ≤0.05 mm.

[0026] Furthermore, a ventilation device comprises the stress-optimized bearing system according to any one of claims 1 to 5 and the manufacturing method of the stress-optimized bearing system according to any one of claims 6 to 9, wherein the noise value of the ventilation device is ≤45dB when operating at full load.

[0027] Beneficial effects:

[0028] 1. The present invention uses the large end of the tapered shaft core to bear the center of gravity of the rotor, and the small end reduces the inertial load through the weight-reducing groove, so that the stress distribution of the bearing inner hole is uniform, the wear rate of the wear-resistant plate is reduced by more than 60%, and the expected life is increased to ≥30,000 hours.

[0029] 2. The present invention forms a lubricating oil retention area through the axial step structure, and cooperates with the capillary penetration effect of the oil-containing bearing to ensure continuous lubrication under high-speed conditions, and the jamming failure rate is reduced by 90%.

[0030] 3. The present invention achieves micron-level matching accuracy between the tapered shaft core and the inner hole of the bearing through the combination of precision turning and powder metallurgy technology, with a tolerance zone of H6 / h5, and the yield rate is increased to more than 98%.

[0031] 4. The present invention provides a plasma sprayed wear-resistant layer with a thickness of 2-5 μm and Ra≤0.1 μm, thereby reducing the friction coefficient of the wear-resistant sheet to 0.08-0.12 and avoiding the environmental pollution problem of the traditional electroplating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 1 is a front view structural diagram of a stress-optimized bearing system according to an embodiment of the present invention;

[0033] Figure 2 1 is a schematic top view of a stress-optimized bearing system according to an embodiment of the present invention;

[0034] Figure 3 The stress-optimized bearing system of one embodiment of the present invention is Figure 2 Schematic diagram of the first form of the tapered shaft core in the cross section of AA;

[0035] Figure 4 The stress-optimized bearing system of one embodiment of the present invention is Figure 2 Schematic diagram of the second form structure of the tapered shaft core in the cross section of AA;

[0036] Figure 5 The stress-optimized bearing system of one embodiment of the present invention is Figure 2 Schematic diagram of the third form structure of the tapered shaft core in the cross section of AA;

[0037] Figure 6 It is a schematic diagram of the conventional structure of a tapered shaft core in the prior art.

[0038] in:

[0039] 7-conical shaft core; 701-large end of the shaft core; 702-small end of the shaft core; 703-weight-reducing groove; 14-bearing; 1401-bearing inner hole; 15-bracket middle tube; 19-wear-resistant plate; 20-fan impeller hub.

[0040] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0043] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections, direct connections, or indirect connections through an intermediate medium; they may refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0045] Reference Figures 1-6 One embodiment of the present invention provides a stress-optimized bearing system and a manufacturing method thereof, comprising:

[0046] The tapered shaft core 7 has a large shaft core end 701 and a small shaft core end 702, wherein the diameter of the large shaft core end 701 is larger than the diameter of the small shaft core end 702;

[0047] The bearing 14 is matched with the tapered shaft core 7, and its inner hole 1401 is a tapered structure adapted to the shaft core;

[0048] The small end 702 of the tapered shaft core 7 is provided with a wear-resistant sheet 19;

[0049] The bearing system is configured such that when the wind turbine rotor is running, the center of gravity of the rotor is located inside the bearing 14 and corresponds to the area of ​​the large end 701 of the shaft core.

[0050] In this embodiment, the diameter of the tapered core 7 at the large end 701 is larger than the diameter of the small end 702, and the taper angle β is 0.5°-3°. The tapered core 7 is manufactured using high-precision machining technology, and its surface undergoes heat treatment (such as carburizing and quenching) to improve hardness and wear resistance.

[0051] The inner bore 1401 of the bearing 14 is tapered, with a taper angle α of 0.5°-3° and β = α ± 0.2°, ensuring a tight fit between the tapered shaft core 7 and the bearing 14. The bearing 14 is manufactured using powder metallurgy, with a porosity of 8%-12% to achieve oil-containing lubrication.

[0052] The wear-resistant sheet 19 is provided at the large end 701 of the conical shaft core 7 and is used to withstand the high stress area during the operation of the fan rotor.

[0053] The center of gravity of the fan rotor is located inside the bearing 14 and corresponds to the area of ​​the large end 701 of the shaft core.

[0054] Optionally, an axial step difference is formed between the large end 701 of the shaft core and the inner hole of the bearing 14, and the size range of the axial step difference is 0.05-0.3 mm.

[0055] An axial step is formed between the large end 701 of the shaft core and the inner bore of the bearing 14. The step is 0.05-0.3mm. This step is precision-machined and inspected by a laser interferometer to ensure a step tolerance of ≤±0.01mm. This axial step design disperses axial loads and reduces contact stress concentration.

[0056] The surface of the wear-resistant sheet 19 is provided with a diamond-like carbon coating, and the coating thickness is 2-5 μm.

[0057] It should be noted that the wear-resistant sheet 19 is made of diamond-like carbon coating with a thickness of 3 μm and a surface friction coefficient of ≤0.08. The diamond-like carbon coating is formed by plasma spraying process and has a low friction coefficient of ≤0.1 and high wear resistance, and a wear rate of ≤0.01mm 3 / N·m.

[0058] The bearing 14 is an oil-containing bearing, and the taper angle α of the bearing inner hole 1401 is 0.5°-3°. The taper angle β of the tapered shaft core 7 satisfies β=α±0.2°. The taper angle of the tapered shaft core 7 preferably adopts β=2°, the taper angle α of the bearing inner hole 1401 is 1.8°, and the axial step difference is 0.15mm.

[0059] Optionally, a weight-reducing groove 703 is further provided at the small end 702 of the shaft core, and the depth of the weight-reducing groove 703 is 10%-25% of the diameter of the shaft core.

[0060] It should be noted that the depth of the weight-reducing groove 703 is 20% of the shaft core diameter. The weight-reducing groove 703 is machined using a CNC milling process, with a surface roughness Ra ≤ 0.8 μm. This reduces the moment of inertia of the rotor system and provides adjustment space for dynamic balancing calibration.

[0061] In summary, the shape of the tapered shaft core 7 has the following features: Figure 3 、 Figure 4 and Figure 5 At least three types.

[0062] A method for manufacturing a stress-optimized bearing system, comprising:

[0063] Step S1: A high-precision CNC lathe is used to precisely turn the core blank to form a tapered core 7 with a predetermined taper angle β. During machining, the cutting speed is controlled at 150-200 m / min, the feed rate is 0.1-0.2 mm / rev, and the cutting tool is a carbide insert, such as a TiAlN-coated tool. After machining, the core surface roughness Ra is ≤ 0.4 μm.

[0064] Step S2: manufacturing the oil-containing bearing 14 by powder metallurgy process, and simultaneously forming the bearing inner hole 1401 matching the taper of the shaft core;

[0065] Step S2: Manufacture the oil-containing bearing 14 using a powder metallurgy process. Iron-based powder is mixed with a graphite lubricant and then pressed into a mold. The iron-based powder particle size is ≤50 μm, and the graphite lubricant accounts for 3%-5%. The sintering temperature is 1100-1200°C, and the holding time is ≥30 minutes. After sintering, the bearing inner bore 1401 is taper-trimmed using electrical discharge machining to ensure that the taper angle α matches the tapered shaft core 7.

[0066] Step S3: Plasma spraying is performed on the surface of the shaft core big end 701 to form a wear-resistant layer. The spraying parameters include:

[0067] Spraying distance: 80-120mm;

[0068] Plasma power: 30-45kW;

[0069] Powder feeding rate: 25-40g / min;

[0070] Substrate preheating temperature: 150-200℃.

[0071] After spraying, the bonding strength between the wear-resistant layer and the substrate is ≥50MPa, and the coating quality is verified by microhardness test (HV0.3≥2000).

[0072] Step S4: After pressing bearing 14 into bracket center tube 15, dynamic balancing calibration is performed on both surfaces P1 and P2. Calibration is performed on the end faces of the shaft core's large end 701 and the weight-reducing groove 703 at the shaft core's small end 702. The dynamic balancing equipment uses a photoelectric sensor, with a calibration speed of 8000 rpm and an error range of ≤±0.001mm.

[0073] A ventilation device comprises a stress-optimized bearing system and a method for manufacturing the stress-optimized bearing system. The ventilation device has a noise value of ≤45dB when operating at full load.

[0074] One end of the tapered shaft core 7 is mounted with a fan impeller hub 20, secured to the tapered shaft core 7 via an interference fit. Bearing 14 is made of copper-based powder metallurgy with a porosity of 10% and an oil content of 15%-20%. Dynamic balancing is performed using a laser vibrometer.

[0075] The tapered shaft core 7 and the bearing inner bore 1401 of the bearing 14 are precisely matched to form a wedge-shaped oil film, distributing contact stress and reducing the risk of local fatigue failure. The diamond-like carbon coating on the shaft core's large end 701 synergizes with the self-lubricating properties of the oil-retaining bearing to significantly reduce friction losses, achieving a friction coefficient of ≤0.1 and enhancing wear resistance. A weight-reducing groove 703 at the shaft core's small end 702 reduces the rotor's moment of inertia and, combined with double-sided dynamic balancing, effectively suppresses vibration at high speeds of 8000 rpm or higher, ensuring more stable operation and extending service life. The wind turbine rotor's center of gravity is located within the shaft core's large end 701 within the bearing 14, further optimizing dynamic load distribution. During manufacturing, CNC turning and powder metallurgy oil-retaining bearings ensure assembly precision. A plasma spray process strengthens the wear-resistant layer's bonding strength. Rubber damping pads and seals ensure operating noise levels of ≤45dB and maintain stability under high-temperature and high-humidity conditions. The system achieves efficient driving, long-life operation and adaptability to extreme environments of ventilation equipment through the synergistic effects of stress balance, efficient friction reduction and dynamic balance.

[0076] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A stress-optimized bearing system, characterized in that: include: A tapered shaft core (7) having a large shaft core end (701) and a small shaft core end (702), wherein the diameter of the large shaft core end (701) is larger than the diameter of the small shaft core end (702); A bearing (14) matched with the tapered shaft core (7) has an inner hole (1401) of the bearing in a tapered structure that matches the shaft core; The small end (702) of the tapered shaft core (7) is provided with a wear-resistant sheet (19); The bearing system is configured such that when the fan rotor is running, the center of gravity of the rotor is located inside the bearing (14) and corresponds to the area of ​​the large end (701) of the shaft core.

2. The stress-optimized bearing system according to claim 1, characterized in that An axial step difference is formed between the large end of the shaft core (701) and the inner hole of the bearing (14), and the size range of the axial step difference is 0.05-0.3 mm.

3. The stress-optimized bearing system according to claim 1, characterized in that The surface of the wear-resistant sheet (19) is provided with a diamond-like carbon coating, and the coating thickness is 2-5 μm.

4. The stress-optimized bearing system according to claim 1, characterized in that The bearing (14) is an oil-containing bearing, the taper angle α of the bearing inner hole (1401) is 0.5°-3°, and the taper angle β of the tapered shaft core (7) satisfies β=α±0.2°.

5. The stress-optimized bearing system according to claim 1, characterized in that It also includes a weight-reducing groove (703) arranged at the small end (702) of the shaft core, and the depth of the weight-reducing groove (703) is 10%-25% of the diameter of the shaft core.

6. A method for manufacturing a stress-optimized bearing system according to any one of claims 1 to 5, wherein the stress-optimized bearing system according to any one of claims 1 to 5 is characterized in that: include: Step S1: forming a tapered shaft core (7) with a predetermined taper angle by precision turning; Step S2: manufacturing an oil-containing bearing (14) by a powder metallurgy process, and simultaneously forming a bearing inner hole (1401) that matches the taper of the shaft core; Step S3: plasma spraying is performed on the surface of the large end (701) of the shaft core to form a wear-resistant layer; Step S4: After the bearing (14) is pressed into the bracket middle tube (15), dynamic balancing calibration is performed.

7. The method for manufacturing a stress-optimized bearing system according to claim 6, characterized in that: In step S3, the spraying parameters include: The spraying distance is 80-120mm; Plasma power is 30-45kW; The powder feeding rate is 25-40g / min; The substrate preheating temperature is 150-200℃.

8. The method for manufacturing a stress-optimized bearing system according to claim 6, characterized in that: The dynamic balance calibration adopts a double-surface correction method of the P1 surface and the P2 surface, and the correction position is located in the end surface of the large end (701) of the shaft core and the weight reduction groove (703) area of ​​the small end (702) of the shaft core.

9. The method for manufacturing a stress-optimized bearing system according to claim 6, characterized in that: When the bearing system rotates at a speed of 8000 rpm or higher, the radial runout of the tapered shaft core (7) is ≤0.02 mm, and the axial runout is ≤0.05 mm.

10. A ventilation device, characterized in that: The invention comprises a stress-optimized bearing system as described in any one of claims 1 to 5 and a method for manufacturing a stress-optimized bearing system as described in any one of claims 6 to 9, wherein the noise value of the ventilation equipment is ≤45dB when running at full load.

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