A machining process for a high-speed rotating mechanical cemented carbide needle-shaped supporting shaft assembly

Abstract

The application discloses a processing technology of a high-speed rotating mechanical hard alloy needle-shaped supporting shaft assembly, which comprises the following steps: step S1, powder mixing; step S2, dry pressing and sintering; step S3, outer diameter grinding; step S4, shaft sleeve pressing; step S5, spherical surface grinding; step S6, laser surface microtexturing; under the action of water guidance, the end spherical surface of the hard alloy needle-shaped supporting shaft shaft in step S5 is subjected to microtexturing treatment by using an ultrafast laser; and step S7, secondary spherical surface grinding. The needle-shaped supporting shaft assembly is made of hard alloy material and processed through the processing steps, and can smoothly pass through a critical point and stably rise to a working rotating speed in a short-time trial operation test of a high-speed rotating machine with a larger volume and weight.

Description

Technical Field

[0001] This invention belongs to the technical field of bearing processing, and in particular to a processing technology for a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly. Background Technology

[0002] To achieve higher performance, high-speed rotating machinery typically increases in size and weight compared to existing mechanical devices. The support system of traditional high-speed rotating machinery consists of a needle-shaped support shaft made of bearing steel and a thrust bearing made of highly wear-resistant materials. The bearing is relatively stationary, while the support shaft rotates synchronously at high speed with the machinery. To reduce wear and power consumption, the axial cross-section of the working section of the support shaft is less than 3 mm. 2 Therefore, it is defined as needle-shaped. To ensure that larger and heavier high-speed rotating machinery can still smoothly pass the critical point and maintain stable operation, a common method is to increase the radial stiffness of the needle-shaped support shaft by an order of magnitude. However, this significantly exacerbates wear on the support shaft and bearing in the contact area, reducing the service life of the support system by more than half. Simultaneously, the increased stiffness of the needle-shaped support shaft also reduces the clearance between the support system shaft and bearing, greatly increasing the probability of collisions under instability. Due to the characteristics of high-speed rotation, even minor collisions pose a high operational risk to the machinery. These adverse factors severely restrict the application prospects and expansion potential of high-speed rotating machinery.

[0003] Cemented carbide possesses high hardness, modulus, bending strength, and machinability, and is commonly used for machining wear-resistant parts. However, the brittle and hard nature of cemented carbide results in poor toughness and insufficient shear resistance under high-speed rotation. Among the various types of cemented carbide, those using cobalt as a binder phase typically exhibit superior toughness compared to other types. By controlling the cobalt content at a certain proportion, a balance between wear resistance and toughness can be achieved.

[0004] In terms of relevant patent inventions and authorized uses, cemented carbide is usually only used as drilling and cutting tools and shaft sealing components. In shaft-bearing systems, it is generally only used as a bearing or bearing sleeve. There is no background for its development and processing as a needle-shaped support shaft for high-speed rotating machinery.

[0005] The significance of solving the above technical problems lies in the fact that, to ensure the spatial dimensions of the needle-shaped support shaft do not change significantly, thereby avoiding a series of other unknown problems, an important research direction is to improve the wear resistance of the support shaft tip. Due to the heat treatment processing limits of materials, the hardness of bearing steel after short-term local quenching is approximately 880 HV, and further heat treatment can easily lead to "overheating". Furthermore, after the hardened layer gradually peels off from the surface treatment process, the hard particles further exacerbate the wear of the shaft and bearing. Therefore, for the needle-shaped shaft, directly using a new type of high-hardness material with high wear resistance and machinability is an inevitable trend. Summary of the Invention

[0006] In response to the problems raised above, this invention proposes a processing technology for a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly.

[0007] A machining process for a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly includes the following steps:

[0008] Step S1: Mixing powder

[0009] WC powder, Co powder, alumina, and rare earth oxides are mixed according to weight percentages to obtain a mixed powder; Step S2: Dry pressing and sintering.

[0010] The mixed powders are mixed, pressed into shape, and sintered in a hot isostatic pressing furnace to form cemented carbide round bars.

[0011] Step S3: Grind the outer diameter

[0012] Using a diamond grinding wheel, the outer diameter of a carbide round bar is ground to form a carbide needle-shaped support shaft; Step S4: Press-fit the shaft sleeve.

[0013] The carbide needle-shaped support shaft is press-fitted into the copper alloy bushing.

[0014] Step S5: Grinding the spherical surface

[0015] The other end of the carbide needle-shaped support shaft is ground into a spherical surface with the required radius of curvature.

[0016] Step S6: Laser-guided surface microtexturing

[0017] Under the guidance of water, an ultrafast laser is used to microtexturize the end spherical surface of the cemented carbide needle-shaped support shaft after grinding in step S5.

[0018] Step S7: Secondary grinding of the spherical surface

[0019] The end spherical surface of the carbide needle-shaped support shaft after step S6 is roughened by using polishing paste and mechanical polishing to finally obtain the carbide needle-shaped support shaft assembly.

[0020] Preferably, in step S1, the mixed powder comprises the following chemical components by mass percentage: Co: 10%–25%; alumina: 2%–5%; rare earth oxides: 2%–5%; WC: balance.

[0021] More preferably, the average particle size of WC is 1.5 μm to 5 μm.

[0022] Preferably, in step S2, the sintering temperature in the hot isostatic pressing furnace is 1400℃~1500℃.

[0023] Preferably, in step S3, the porosity of the formed cemented carbide needle-shaped support shaft is not higher than A02B00.

[0024] Preferably, in step S3, the outer diameter of the carbide needle-shaped support shaft is 1.0 mm to 2.2 mm after grinding.

[0025] Preferably, in step S4, the interference fit between the carbide needle-shaped support shaft and the copper alloy bushing is 5μm to 20μm.

[0026] Preferably, the coaxiality between the carbide needle-shaped support shaft and the copper alloy bushing is 0.01mm to 0.08mm.

[0027] Preferably, in step S6, the diameter of the micropores on the end spherical surface after microtexturing treatment is 25μm to 75μm, the depth of the micropores is 25μm to 50μm, and the area distribution law is 30% to 50%.

[0028] Preferably, in step S7, the surface roughness of the end spherical surface of the cemented carbide needle-shaped support shaft after grinding and polishing is 0.03μm to 0.08μm.

[0029] The beneficial effects of this invention are:

[0030] The cemented carbide needle-shaped support shaft rod sintered using this method has an overall hardness of not less than 88HRA, a bending strength of not less than 2800MPa, and a porosity of not more than A02B00.

[0031] The needle-shaped support shaft assembly manufactured using the aforementioned cemented carbide material successfully passed the critical point and stably reached the operating speed during a short-term trial run of a larger, heavier, high-speed rotating machine. After the trial, the spherical end surface of the cemented carbide needle-shaped support shaft showed only slight annular wear marks, and the shaft itself did not experience shear fracture; in contrast, the spherical end surface of the control group's hardened bearing steel needle-shaped support shaft exhibited a wide range of fatigue wear morphology. Overall, the needle-shaped support shaft assembly made of cemented carbide material demonstrates superior wear resistance compared to that made of hardened bearing steel. Attached Figure Description

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0033] Figure 1 The processing flow of this invention;

[0034] Figure 2 Schematic diagram of a cemented carbide needle-shaped support shaft;

[0035] Figure 3 Schematic diagram of copper alloy bushing;

[0036] Figure 4 A schematic diagram of the assembled carbide needle-shaped support shaft assembly;

[0037] Figure 5 A schematic diagram showing the circular microporous texture on the spherical end face of a cemented carbide needle-shaped support shaft and its implementation location. Detailed Implementation

[0038] First, it should be noted that the specific structure, features, and advantages of the present invention will be described in detail below by way of examples. However, all descriptions are for illustrative purposes only and should not be construed as limiting the present invention in any way. Furthermore, any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the accompanying drawings, can still be arbitrarily combined or deleted among these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned herein. Additionally, for the sake of simplifying the drawings, the same or similar technical features may be indicated only in one place in the same drawing.

[0039] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] The following is in conjunction with the appendix Figure 1-5 This invention will be described in detail.

[0041] Example 1:

[0042] A machining process for a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly includes the following steps:

[0043] Step S1: Mixing powder

[0044] WC powder, Co powder, alumina, and rare earth oxides are mixed according to weight percentages to obtain a mixed powder; Step S2: Dry pressing and sintering.

[0045] The mixed powders are mixed, pressed into shape, and sintered in a hot isostatic pressing furnace to form cemented carbide round bars.

[0046] Step S3: Grind the outer diameter

[0047] Using a diamond grinding wheel, the outer diameter of a carbide round bar is ground to form a carbide needle-shaped support shaft; Step S4: Press-fit the shaft sleeve.

[0048] The carbide needle-shaped support shaft is press-fitted into the copper alloy bushing.

[0049] Step S5: Grinding the spherical surface

[0050] The other end of the carbide needle-shaped support shaft is ground into a spherical surface with the required radius of curvature.

[0051] Step S6: Laser-guided surface microtexturing

[0052] Under the guidance of water, an ultrafast laser is used to microtexturize the end spherical surface of the cemented carbide needle-shaped support shaft after grinding in step S5.

[0053] Step S7: Secondary grinding of the spherical surface

[0054] The end spherical surface of the carbide needle-shaped support shaft after step S6 is roughened by using polishing paste and mechanical polishing to finally obtain the carbide needle-shaped support shaft assembly.

[0055] Working principle:

[0056] Medium-grained WC powder, Co powder, alumina, and rare earth oxides, which are close to single crystals, are mixed in a certain weight percentage and then dried. The mixed powder is pressed into shape and sintered in a hot isostatic pressing furnace. The sintered cemented carbide needle-shaped support shaft is then ground to the required outer diameter using a diamond grinding wheel.

[0057] The carbide needle-shaped support shaft is press-fitted into the copper alloy bushing using an interference fit method, controlling the interference and adjusting the coaxiality.

[0058] First, the end of the carbide needle-shaped support shaft is ground into a spherical surface with the required radius of curvature. Then, under water guidance, an ultrafast laser is used to microtexturize the spherical end of the needle-shaped support shaft. After processing, polishing paste and mechanical polishing are used to polish the spherical end of the needle-shaped support shaft to a specific surface roughness.

[0059] The cemented carbide needle-shaped support shaft assembly with spherical microtextured ends is not limited to a certain size during the processing and forming process. Support shafts of various specifications can be developed according to design needs and meet the requirements of different high-speed rotating machinery.

[0060] Furthermore, in the embodiments, it can also be considered that in step S1, the mixed powder includes the following chemical components by mass percentage: Co: 10% to 25%; alumina: 2% to 5%; rare earth oxides: 2% to 5%; WC: balance.

[0061] Furthermore, in the embodiments, the average particle size of WC can be considered to be 1.5 μm to 5 μm.

[0062] Furthermore, in the embodiments, it can be considered that in step S2, the sintering temperature in the hot isostatic pressing furnace is 1400℃~1500℃.

[0063] Furthermore, in the embodiments, it can also be considered that in step S3, the porosity of the formed cemented carbide needle-shaped support shaft is not higher than A02B00.

[0064] Furthermore, in the embodiments, it can also be considered that in step S3, the outer diameter of the carbide needle-shaped support shaft is 1.0mm to 2.2mm after grinding.

[0065] Furthermore, in the embodiments, it can be considered that in step S4, the interference fit between the cemented carbide needle-shaped support shaft and the copper alloy bushing is 5μm to 20μm.

[0066] Furthermore, in the embodiments, the coaxiality between the carbide needle-shaped support shaft and the copper alloy bushing can be considered to be 0.01mm to 0.08mm.

[0067] Furthermore, in the embodiments, it can also be considered that in step S6, the diameter of the end spherical micropores after microtexturing treatment is 25μm to 75μm, the depth of the micropores is 25μm to 50μm, and the area distribution law is 30% to 50%.

[0068] Furthermore, in the embodiments, it can also be considered that in step S7, the surface roughness of the end spherical surface of the cemented carbide needle-shaped support shaft after grinding and polishing is 0.03μm to 0.08μm.

[0069] Application Example 1:

[0070] To enable those skilled in the art to more clearly understand the technical solution of the present invention, the implementation method of its processing is explained using a cemented carbide needle-shaped support shaft assembly with a diameter of φ1.5mm, a diameter of SR1.68mm, and a cobalt content of 18% as an example.

[0071] The specific process includes the following steps:

[0072] 1. WC powder with a particle size of 2μm to 4μm is mixed with 18wt% Co powder, and a total of about 7wt% alumina and rare earth oxides as sintering aids. The powder is then pressed into shape and sintered in a hot isostatic pressing furnace at 1450℃ to form a cemented carbide round bar with a diameter of 1.6mm.

[0073] 2. Using a diamond grinding wheel, the outer diameter of the carbide round bar is ground to 1.5mm, and the tail end is ground and chamfered to form a carbide needle-shaped support shaft rod.

[0074] 3. Insert the carbide needle-shaped support shaft into the copper alloy bushing with the corresponding inner diameter using interference fitting, controlling the interference to be below 15μm, and check and fine-tune the coaxiality to 0.08mm.

[0075] 4. Grind the end spherical surface of the carbide needle-shaped support shaft to achieve a radius of curvature of SR1.70mm.

[0076] 5. Using a green pulsed laser and water guidance, the end of the carbide needle-shaped support shaft is spherically microtextured to form a circular micropore with a diameter of 50μm±5μm, a depth of 30μm±5μm, and an area distribution of 40%.

[0077] 6. Using polishing paste and mechanical polishing, the roughness of the spherical end surface of the carbide needle support shaft is polished to 0.03μm~0.06μm, and the radius of curvature is finally SR1.68mm, thus producing a carbide needle support shaft assembly that meets the requirements.

[0078] In summary, this invention provides a machining process for a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly that improves the wear resistance of cemented carbide.

[0079] The above embodiments have provided a detailed description of the present invention, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A machining process for a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly, characterized in that, Includes the following steps: Step S1: Mixing powder WC powder, Co powder, alumina, and rare earth oxides are mixed according to weight percentages to obtain a mixed powder; Step S2: Dry pressing and sintering The mixed powders are mixed, pressed into shape, and sintered in a hot isostatic pressing furnace to form cemented carbide round bars. Step S3: Grind the outer diameter A diamond grinding wheel is used to grind the outer diameter of a carbide round bar to form a carbide needle-shaped support shaft. Step S4: Press-fit the bushing The carbide needle-shaped support shaft is press-fitted into the copper alloy bushing. Step S5: Grinding the spherical surface The other end of the carbide needle-shaped support shaft is ground into a spherical surface with the required radius of curvature; Step S6: Laser-guided surface microtexturing Under the guidance of water, an ultrafast laser is used to microtexturize the end spherical surface of the cemented carbide needle-shaped support shaft after grinding in step S5. Step S7: Secondary grinding of the spherical surface The end spherical surface of the carbide needle-shaped support shaft after step S6 is roughened by using polishing paste and mechanical polishing to finally obtain the carbide needle-shaped support shaft assembly.

2. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 1, characterized in that: In step S1, the mixed powder comprises the following chemical components by mass percentage: Co: 10%–25%; alumina: 2%–5%; rare earth oxides: 2%–5%; WC: balance.

3. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 2, characterized in that: The average particle size of WC is 1.5 μm to 5 μm.

4. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 1, characterized in that: In step S2, the sintering temperature in the hot isostatic pressing furnace is 1400℃~1500℃.

5. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 1, characterized in that: In step S3, the porosity of the formed cemented carbide needle-shaped support shaft is not higher than A02B00.

6. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 1, characterized in that: In step S3, the outer diameter of the carbide needle-shaped support shaft is 1.0 mm to 2.2 mm after grinding.

7. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 1, characterized in that: In step S4, the interference fit between the carbide needle-shaped support shaft and the copper alloy bushing is 5μm to 20μm.

8. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 7, characterized in that: The coaxiality between the carbide needle-shaped support shaft and the copper alloy bushing is 0.01mm to 0.08mm.

9. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 1, characterized in that: In step S6, the diameter of the micropores on the end spherical surface after microtexturing treatment is 25μm to 75μm, the depth of the micropores is 25μm to 50μm, and the area distribution law is 30% to 50%.

10. The machining process of a high-speed rotating machinery cemented carbide needle-shaped support shaft assembly according to claim 1, characterized in that: In step S7, the surface roughness of the end spherical surface of the cemented carbide needle-shaped support shaft after grinding and polishing is 0.03μm to 0.08μm.

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