Propeller stainless steel shaft outer surface hardness improvement method

Abstract

The application discloses a propeller stainless steel shaft outer surface hardness improving method, and belongs to the field of propeller stainless steel shaft outer surface hardness improving method.The propeller stainless steel shaft comprises a rolled shaft, an inner hole and an outer shaft, the left end of the rolled shaft is connected with the right end of the outer shaft, the inner part of the outer shaft is provided with the inner hole, the inner part of the rolled shaft is provided with a through hole communicated with the inner hole, and the diameter of the rolled shaft is smaller than the diameter of the outer shaft.The improving method comprises the following steps: step 1, rolling treatment is performed on the outer side of the rolled shaft; and step 2, after the rolling treatment is completed, the outer side of the rolled shaft and the outer shaft is subjected to turning processing until the preset standard is reached, and the outer surface hardness improving is ended.The design only needs to be rolled several times to meet the use requirement, the hardness is obviously improved, the processing period is short, and the manufacturing cost is low.

Description

Technical Field

[0001] This invention relates to an improvement in the technology for enhancing the hardness of a propeller shaft, belonging to the field of parts processing, and particularly to a method for enhancing the hardness of the outer surface of a stainless steel propeller shaft. Background Technology

[0002] Stainless steel parts are widely used in marine equipment due to their excellent corrosion resistance, especially as propulsion power units. Because they operate underwater for extended periods and are immersed in seawater, they require exceptionally high corrosion resistance. Since the propeller and support shaft form a sliding friction pair, long-term use will inevitably cause wear on the parts. The support shaft is made of 316L stainless steel, which has a relatively low hardness (HB approximately 173) and poor wear resistance. However, the rubber of the water-lubricated support bearing it is paired with has a Shore A hardness of 85-90. In long-term wear tests, the support shaft is highly susceptible to wear and premature failure, making it unsuitable for direct use as a friction pair. Therefore, it is necessary to treat the support shaft to improve its surface hardness before use.

[0003] Considering that the support shaft is immersed in the sea for a long time, while improving the surface hardness of the support shaft, its corrosion resistance should not be reduced. In order to improve the surface hardness of the support shaft, the initial technical solution was to use a cladding process, that is, to clad a layer of special alloy material on the surface of the support shaft to improve its surface hardness and ensure its corrosion resistance. However, this process has many drawbacks, mainly: the cladding process is relatively complex, the quality stability is not high, and cladding defects are prone to occur; the manufacturing cycle of the cladding process is long, the cladding process generates a lot of heat, which can cause certain thermal deformation of the parts, and the process design needs to reserve machining allowance, which leads to the complexity of subsequent processing steps and a long processing cycle.

[0004] Chinese patent application CN202110634199.3, filed on June 7, 2021, discloses a surface treatment process for metallic materials. Specifically, this invention relates to the field of surface treatment technology for metallic materials. Shot peening and micro-arc oxidation can increase the surface hardness of zirconium alloys by 60% and generate a dense ceramic-type zirconium oxide film with a thickness of approximately 3.4 micrometers. Shot peening and micro-arc oxidation significantly enhance the wear resistance of zirconium alloy surfaces, greatly reducing the wear coefficient and wear volume by 65%. The corrosion resistance of the treated zirconium alloy samples is also significantly improved. Overall, shot peening and micro-arc oxidation are low-cost and can significantly increase the overall performance of zirconium alloys. However, the prior art still does not solve the problems of complex processes and long cycles in existing hardness-enhancing technologies.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this patent application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of complex processes and long cycles in the prior art, and to provide a method for improving the hardness of the outer surface of a stainless steel propeller shaft with a shorter process and shorter cycle.

[0007] To achieve the above objectives, the technical solution of the present invention is: a method for improving the hardness of the outer surface of a stainless steel shaft for a propeller, wherein the stainless steel shaft includes a rolling shaft, an inner hole and an outer shaft, the left end of the rolling shaft is connected to the right end of the outer shaft, the outer shaft has an inner hole inside, the rolling shaft has a through hole communicating with the inner hole inside, the diameter of the rolling shaft is smaller than the diameter of the outer shaft, and the improvement method includes:

[0008] Step 1: Roll the outer circumference of the rolling shaft;

[0009] Step 2: After the rolling process is completed, the outer perimeter of the rolling shaft and the outer shaft is machined until it reaches the preset standard, thus ending this external surface hardness improvement.

[0010] The lifting method also includes a pre-processing step performed before step one. The pre-processing step includes: selecting the pusher shaft to be lifted, placing the rolling shaft with the outer shaft facing up and the outer shaft facing down vertically, clamping the outer side of the rolling shaft, and then pre-processing the rolling shaft and the outer shaft.

[0011] The pretreatment of the rolling shaft refers to machining the rolling shaft so that the surface roughness of the rolling shaft is Ra3.2 and the ratio of the inner diameter of the through hole to the outer diameter of the rolling shaft is 0.1-0.8.

[0012] The aforementioned pretreatment of the outer shaft refers to machining the surface of the outer shaft to achieve a surface roughness of Ra3.2, and ensuring that the ratio of the inner diameter of the inner hole to the outer diameter of the outer shaft is 0.1-0.8.

[0013] The pretreatment of the outer shaft also includes: after the machining of the outer shaft is completed, an overall colorimetric flaw detection inspection is performed. This inspection includes: first, cleaning the surface of the roller shaft and the outer shaft to be colored with a cleaning agent to remove oil and impurities from the surface; then, spraying the colorant onto the surface of the roller shaft and the outer shaft; allowing it to stand for a preset time to allow the colorant to fully penetrate; then, rinsing off the colorant from the surface of the roller shaft and the outer shaft with a cleaning agent; then, spraying a layer of developer onto the surface of the roller shaft and the outer shaft; allowing it to stand for a preset time; and then observing whether there are defects on the surface of the roller shaft and the outer shaft. If defects are found, the pusher shaft is scrapped; if no defects are found, the next step is performed.

[0014] The specific operation of the rolling process is as follows: the rolling shaft is placed vertically with the outer shaft facing up and the outer shaft facing down. The outer side of the outer shaft is clamped. The rolling cutter is moved so that the outer surface of the circular rolling head of the rolling cutter is in contact with the surface of the rolling shaft. Then the pusher shaft is rotated. At this time, the rolling head rotates on the outside of the rolling shaft, thereby forming a hard extrusion and performing the rolling process.

[0015] The rolling process also includes: performing a data analysis after each rolling process, and ending when the surface hardness of the rolling shaft is found to be greater than 232 (HB) and the surface roughness is greater than Ra3.2.

[0016] The preset standard for the turning process is: the outer diameter of the outer shaft is 0.1-0.15 mm larger than the outer diameter of the rolling shaft.

[0017] The lifting method also includes an inspection step after the end of step two. The inspection step includes: after turning, inspecting the outer diameter of the rolling shaft and the outer shaft. If the inspection data is not qualified, the pusher shaft is corrected until the inspection data meets the preset standard.

[0018] The process of calibrating the propeller shaft refers to placing the rolling shaft vertically with the outer shaft facing up and the outer shaft facing down, clamping the outer side of the outer shaft, and calibrating the runout of the outer shaft to be less than 0.03mm, and calibrating the runout of the rolling shaft to be less than 0.03mm.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. In this invention, a method for improving the hardness of the outer surface of a stainless steel propeller shaft involves rolling the outer circumference of the rolling shaft. The rolling shaft is placed vertically with the outer shaft facing downwards, and the outer circumference of the outer shaft is clamped. The rolling cutter is moved so that the outer surface of the circular rolling head of the rolling cutter contacts the surface of the rolling shaft. Then, the propeller shaft is rotated, causing the rolling head to rotate on the outside of the rolling shaft, thus forming a hard extrusion process. Through cold work hardening, the hardness of the stainless steel support shaft surface is effectively improved. The surface roughness of the rolled shaft after rolling can reach Ra0.4, and the hardness index can reach HB240 or higher. Simultaneously, the corrosion resistance of the material is not altered. Only a few rolling cycles are needed to meet the usage requirements. The hardness improvement is significant, the processing cycle is short, and the manufacturing cost is low. Therefore, this design has a short processing cycle and low manufacturing cost.

[0021] 2. In the method for improving the outer surface hardness of a stainless steel propeller shaft according to the present invention, after the rolling process is completed, the outer perimeter of the rolled shaft and the outer shaft are machined until a preset standard is met. The outer diameter of the outer shaft is 0.1-0.15 mm larger than that of the rolled shaft. Since the outer surface roughness of the rolled shaft and the outer shaft is poor, the machining process improves the surface roughness, greatly facilitating subsequent hardness improvement. Therefore, this design improves the surface roughness and significantly enhances the hardness. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] In the diagram: 1. Stainless steel shaft; 2. Rolled shaft; 3. Inner hole; 31. Through hole; 4. Outer shaft. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] See Figure 1 A method for improving the hardness of the outer surface of a stainless steel shaft for a propeller, wherein the stainless steel shaft 1 includes a rolling shaft 2, an inner hole 3 and an outer shaft 4, the left end of the rolling shaft 2 is connected to the right end of the outer shaft 4, the outer shaft 4 has an inner hole 3 inside, the rolling shaft 2 has a through hole 31 communicating with the inner hole 3 inside, the diameter of the rolling shaft 2 is smaller than the diameter of the outer shaft 4, and the improvement method includes;

[0026] Step 1: Roll the outer perimeter of the rolling shaft 2;

[0027] Step 2: After the rolling process is completed, the outer sides of the rolling shaft 2 and the outer shaft 4 are machined until the preset standard is met, thus ending the surface hardness improvement process.

[0028] The lifting method also includes a pre-processing step performed before step one. The pre-processing step includes: selecting the pusher shaft 1 to be lifted, placing the rolling shaft 2 with the outer shaft 4 facing down vertically, clamping the outer side of the rolling shaft 2, and then pre-processing the rolling shaft 2 and the outer shaft 4.

[0029] The pretreatment of the rolling shaft 2 refers to processing the rolling shaft 2 so that the surface roughness of the rolling shaft 2 is Ra3.2, and the ratio of the inner diameter of the through hole 31 to the outer diameter of the rolling shaft 2 is 0.1-0.8.

[0030] The pretreatment of the outer shaft 4 refers to machining the surface of the outer shaft 4 so that the surface roughness of the outer shaft 4 is Ra3.2, and the ratio of the inner diameter of the inner hole 3 to the outer diameter of the outer shaft 4 is 0.1-0.8.

[0031] The pretreatment of the outer shaft 4 also includes: after the machining of the outer shaft 4 is completed, an overall colorimetric flaw detection inspection is performed. This inspection includes: first, cleaning the surfaces of the roller shaft 2 and the outer shaft 4 to be colored with a cleaning agent to remove oil and impurities from the surface; then, spraying the colorant onto the surface of the roller shaft 2 and the outer shaft 4; allowing it to stand for a preset time to allow the colorant to fully penetrate; then, rinsing off the colorant from the surface of the roller shaft 2 and the outer shaft 4 with a cleaning agent; then, spraying a layer of developer onto the surface of the roller shaft 2 and the outer shaft 4; allowing it to stand for a preset time; and then observing whether there are defects on the surface of the roller shaft 2 and the outer shaft 4. If defects are found, the pusher shaft 1 is scrapped; if no defects are found, the next step is performed.

[0032] The specific operation of the rolling process is as follows: the rolling shaft 2 is placed vertically with the outer shaft 4 facing down, the outer side of the outer shaft 4 is clamped, the rolling cutter is moved so that the outer circular surface of the circular rolling head of the rolling cutter is in contact with the surface of the rolling shaft 2, and then the pusher shaft 1 is rotated. At this time, the rolling head rotates on the outside of the rolling shaft 2, thereby forming a hard extrusion and performing the rolling process.

[0033] The rolling process also includes: performing a data analysis after each rolling process, and ending when the surface hardness of the rolling shaft 2 is found to be greater than 232 (HB) and the surface roughness is greater than Ra3.2.

[0034] The preset standard for the turning process is that the outer diameter of the outer shaft 4 is 0.1-0.15 mm larger than the outer diameter of the rolling shaft 2.

[0035] The lifting method also includes an inspection step after the end of step two. The inspection step includes: after turning, inspecting the outer diameter of the rolling shaft 2 and the outer shaft 4. If the inspection data is not qualified, the pusher shaft 1 is corrected until the inspection data meets the preset standard.

[0036] The calibration of the thruster shaft 1 refers to: placing the rolling shaft 2 upward and the outer shaft 4 downward vertically, clamping the outer side of the outer shaft 4, and calibrating the runout of the outer shaft 4 to be less than 0.03mm, and calibrating the runout of the rolling shaft 2 to be less than 0.03mm.

[0037] Example 1:

[0038] A method for improving the surface hardness of a stainless steel propeller shaft, wherein the stainless steel shaft 1 includes a rolling shaft 2, an inner hole 3, and an outer shaft 4. The left end of the rolling shaft 2 is connected to the right end of the outer shaft 4. The outer shaft 4 has an inner hole 3 inside, and the rolling shaft 2 has a through hole 31 communicating with the inner hole 3 inside. The diameter of the rolling shaft 2 is smaller than the diameter of the outer shaft 4. The improvement method includes: Step 1: Rolling the outer periphery of the rolling shaft 2; Step 2: After the rolling treatment is completed, turning the outer periphery of the rolling shaft 2 and the outer shaft 4 until the preset standard is reached, thus ending the surface hardness improvement.

[0039] Example 2:

[0040] Example 2 is basically the same as Example 1, except that:

[0041] A method for improving the hardness of the outer surface of a stainless steel propeller shaft, the method further includes a pretreatment step before step one, the pretreatment step including: selecting the propeller shaft 1 to be improved, placing the rolled shaft 2 upward and the outer shaft 4 downward vertically, clamping the outer side of the rolled shaft 2, and then pretreating the rolled shaft 2 and the outer shaft 4; the pretreatment of the rolled shaft 2 refers to: machining the rolled shaft 2, the size of the rolled shaft 2 being Φ141 (0-0.05) mm, the surface roughness being Ra3.2, controlling the inner hole size to Φ111 mm, and the ratio of the inner diameter of the through hole 31 to the outer diameter of the rolled shaft 2 being 0.1-0.8; the pretreatment of the outer shaft 4 refers to: machining the outer shaft 4 to φ146 (-0.07--0.05) mm, the surface roughness being Ra a3.2, the measured surface hardness of the support shaft is HB=180, and the ratio of the inner diameter of the inner hole 3 to the outer diameter of the outer shaft 4 is 0.78; the pretreatment of the outer shaft 4 also includes: after the machining of the outer shaft 4 is completed, an overall colorimetric flaw detection inspection is performed. This inspection includes: first, cleaning the surface of the roller shaft 2 and the outer shaft 4 to be colored with a cleaning agent to remove oil and impurities from the surface, then spraying the colorant onto the surface of the roller shaft 2 and the outer shaft 4, letting it stand for a preset time to allow the colorant to fully penetrate, then rinsing off the colorant from the surface of the roller shaft 2 and the outer shaft 4 with a cleaning agent, then spraying a layer of developer onto the surface of the roller shaft 2 and the outer shaft 4, letting it stand for a preset time, and observing whether there are defects on the surface of the roller shaft 2 and the outer shaft 4. If defects are found, the pusher shaft 1 is scrapped; if no defects are found, the next step is performed.

[0042] Example 3:

[0043] Example 3 is basically the same as Example 2, except that:

[0044] A method for improving the surface hardness of a stainless steel shaft for a propeller includes a rolling process where the rolling shaft 2 is placed vertically with the outer shaft 4 facing downwards. The outer side of the outer shaft 4 is clamped, and the rolling tool is moved so that the outer surface of the circular rolling head of the rolling tool is in contact with the surface of the rolling shaft 2. Then, the propeller shaft 1 is rotated, at which point the rolling head rotates on the outside of the rolling shaft 2, thereby forming a hard extrusion and performing the rolling process. The rolling process also includes performing a data analysis after each rolling operation. When the surface hardness of the rolling shaft 2 is found to be greater than HB 232 and the surface roughness is greater than Ra 3.2, the process ends. The preset standard for the turning process is that the outer diameter of the outer shaft 4 is 0.1-0.15 mm larger than the outer diameter of the rolling shaft 2.

[0045] The first turning operation used the following machining parameters: ap (depth of cut) = 0.05 mm, S = 35 r / min, f = 0.2 mm / r. The relevant data after roller burnishing are as follows:

[0046] 1 φ140.78 244

[0047] The second turning operation was performed with the following machining parameters: ap = 0.05 mm, S = 35 r / min, f = 0.2 mm / r. The relevant data after the roll forming are as follows:

[0048] 1 φ140.68 222

[0049] The third turning operation was performed with the following machining parameters: ap = 0.05 mm, S = 35 r / min, f = 0.2 mm / r. The relevant data after the rolling process are as follows:

[0050] 1 φ140.59 206

[0051] The fourth turning operation was performed with the following machining parameters: ap = 0.05 mm, S = 35 r / min, f = 0.2 mm / r. The relevant data after the rolling process are as follows:

[0052] 1 φ140.49 176

[0053] As can be seen from the table above, the hardness of the outer surface of the roller 2 is significantly reduced after each turning operation. Therefore, we can conclude that the roller rolling operation increases the hardness of the outer surface of the roller 2.

[0054] The lifting method also includes an inspection step after the end of step two. The inspection step includes: after turning, inspecting the outer diameter of the rolling shaft 2 and the outer shaft 4. If the inspection data is not qualified, the pusher shaft 1 is corrected until the inspection data meets the preset standard.

[0055] The calibration of the thruster shaft 1 refers to: placing the rolling shaft 2 upward and the outer shaft 4 downward vertically, clamping the outer side of the outer shaft 4, and calibrating the runout of the outer shaft 4 to be less than 0.03mm, and calibrating the runout of the rolling shaft 2 to be less than 0.03mm.

[0056] Example 4:

[0057] Example 4 is basically the same as Example 3, except that:

[0058] A method for improving the hardness of the outer surface of a stainless steel propeller shaft, with the following rolling data:

[0059] The relevant data before rolling are as follows:

[0060] 1 φ140.905 Ra2.0 174 2 φ140.915 Ra4.0 175 3 φ140.92 Ra4.0 177

[0061] The first rolling process was performed with the following parameters: ap = 0.05 mm, S = 30 r / min, f = 0.3 mm / r. The relevant data after rolling are as follows:

[0062] 1 φ140.895 Ra0.5 201 2 φ140.90 Ra2.0 204 3 φ140.905 Ra2.4 206

[0063] The second rolling process was performed with the following parameters: ap = 0.06 mm, S = 30 r / min, f = 0.3 mm / r. The relevant data after rolling are as follows:

[0064] 1 φ140.885 Ra0.4 226 2 φ140.89 Ra1.0 221 3 φ140.89 Ra0.9 217

[0065] The third rolling process was performed with the following parameters: ap = 0.06 mm, S = 30 r / min, f = 0.2 mm / r. The relevant data after rolling are as follows:

[0066]

[0067]

[0068] The fourth rolling process was performed with the following parameters: ap = 0.07 mm, S = 35 r / min, f = 0.2 mm / r. The relevant data after the rolling process are as follows:

[0069] 1 φ140.885 Ra0.25 254 2 φ140.89 Ra0.6 253 3 φ140.89 Ra0.4 253

[0070] According to the process verification, the surface hardness HB of the rolled shaft 2 after four rolling processes reached about 253. Before rolling, the original surface hardness HB of the rolled shaft 2 was about 175. Through four rolling processes, the surface hardness HB of the rolled shaft 2 increased by about 78. The final surface hardness of the rolled shaft 2 reached HB = 255-258. Compared with the initial HB = 180, the surface hardness was significantly improved, which fully meets the requirement of hardness HB ≥ 232.

[0071] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A method for improving the hardness of the outer surface of a stainless steel propeller shaft, wherein the stainless steel propeller shaft (1) includes a rolling shaft (2), an inner hole (3), and an outer shaft (4), the left end of the rolling shaft (2) is connected to the right end of the outer shaft (4), the outer shaft (4) has an inner hole (3) inside, the rolling shaft (2) has a through hole (31) communicating with the inner hole (3) inside, and the diameter of the rolling shaft (2) is smaller than the diameter of the outer shaft (4), characterized in that... The improvement method includes: Select the stainless steel shaft (1) of the pusher to be lifted, place the rolling shaft (2) with the outer shaft (4) facing up and vertically with the outer shaft (4) facing down, clamp the outer side of the rolling shaft (2), and then pre-treat the rolling shaft (2) and the outer shaft (4); Step 1: Roll the outer circumference of the rolling shaft (2); Place the rolling shaft (2) with the outer shaft (4) facing up vertically and clamp the outer side of the outer shaft (4). Move the rolling cutter so that the outer surface of the circular rolling head of the rolling cutter is in contact with the surface of the rolling shaft (2). Then rotate the pusher stainless steel shaft (1). At this time, the rolling head rotates on the outside of the rolling shaft (2), thereby forming a hard extrusion and performing rolling processing. A data analysis is performed after each rolling process. The process ends when the surface hardness of the rolling shaft (2) is required to be greater than 232 (HB) and the surface roughness is greater than Ra3.

2. Step 2: After the rolling process is completed, the outer side of the rolling shaft (2) and the outer shaft (4) is machined until the preset standard is reached, and then the surface hardness improvement is completed. The preset turning standard is that the outer diameter of the outer shaft is 0.1-0.15mm larger than the outer diameter of the rolling shaft, and the runout of both the rolling shaft and the outer shaft is corrected to be less than 0.03mm.

2. The method for improving the hardness of the outer surface of a stainless steel propeller shaft according to claim 1, characterized in that: The pretreatment of the rolling shaft (2) refers to processing the rolling shaft (2) so that the surface roughness of the rolling shaft (2) is Ra3.2 and the ratio of the inner diameter of the through hole (31) to the outer diameter of the rolling shaft (2) is 0.1-0.

8.

3. The method for improving the hardness of the outer surface of a stainless steel propeller shaft according to claim 1, characterized in that: The pretreatment of the outer shaft (4) refers to machining the surface of the outer shaft (4) so ​​that the surface roughness of the outer shaft (4) is Ra3.2 and the ratio of the inner diameter of the inner hole (3) to the outer diameter of the outer shaft (4) is 0.1-0.

8.

4. The method for improving the hardness of the outer surface of a stainless steel propeller shaft according to claim 3, characterized in that: The pretreatment of the outer shaft (4) also includes: after the machining of the outer shaft (4) is completed, an overall color flaw detection inspection is carried out. The inspection includes: first, cleaning the surface of the roller shaft (2) and the outer shaft (4) to be colored with a cleaning agent to remove oil and impurities from the surface; then spraying the colorant on the surface of the roller shaft (2) and the outer shaft (4); letting it stand for a preset time to allow the colorant to fully penetrate; then rinsing off the colorant on the surface of the roller shaft (2) and the outer shaft (4) with a cleaning agent; then spraying a layer of developer on the surface of the roller shaft (2) and the outer shaft (4); letting it stand for a preset time; and then observing whether there are defects on the surface of the roller shaft (2) and the outer shaft (4). When there are defects, the stainless steel shaft (1) of the pusher is scrapped; when there are no defects, the next step is carried out.

5. The method for improving the hardness of the outer surface of a stainless steel propeller shaft according to claim 1, characterized in that: The lifting method also includes an inspection step after the end of step two. The inspection step includes: after turning, inspecting the outer diameter of the rolling shaft (2) and the outer shaft (4). If the inspection data is not qualified, the stainless steel shaft (1) of the pusher is corrected until the inspection data meets the preset standard.

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