Method for determining spinning roller surface strengthening process
By subjecting the rotating wheel to surface composite QPQ salt bath treatment, the problems of low surface strength and short service life of the rotating wheel are solved, the hardness is improved and the wear resistance is optimized, and the service life of the rotating wheel is extended.
Patent Information
- Application Number
- CN202411603416.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-11
- Publication Date
- 2025-01-24
- Estimated Expiration
- 2044-11-11
AI Technical Summary
In the prior art, the rotary wheel has a low surface strength and a short service life, making it difficult to meet the complex working conditions of high load, high wear resistance and contact fatigue resistance.
By preparing test blocks of the same material, the surface nitrogen seepage treatment, nitrogen carbon co -seepage treatment, and surface composite QPQ salt bath treatment are performed. The best way to strengthen the surface.
The surface hardness of the rotating wheel is improved and the wear resistance is optimized, which extends the service life of the rotating wheel. Specifically, the service life is increased by 10%.
Smart Images
Figure CN119351940A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of mechanical processing, in particular to a method for determining a surface strengthening process of a rotary wheel. Background Art
[0002] Metal spinning is a gradual and continuous incremental forming process completed by accumulating local micro-deformations. At each processing moment, the contact area between the spinning wheel and the workpiece is small, which can be approximated as point deformation. Therefore, the spinning force is relatively small compared to other pressure processing processes such as forging, rolling, and extrusion. Large-sized parts can be processed by equipment with lower pressure. It is a typical "low-load forming" labor-saving forming process method. The force diagram at the contact point between the spinning wheel and the workpiece is shown in the figure. Figure 1 As shown in the figure, it can be seen that the forces on the spinning wheel and the workpiece surface are complex during the spinning process, and the decomposition of the resultant force P in the radial, axial and tangential directions are P L , P R , P T' These three forces determine the complexity and wear of the wheel working conditions, among which P L , P R It has a direct impact on the wear of the wheel. The working surface of the wheel is in extrusion contact with the heavy-loaded and small contact surface of the workpiece, and the wheel body is connected to the transmission parts. Therefore, the working surface of the wheel must have high quenching hardness, strength, rigidity, wear resistance, and the ability to resist small deformation and certain impacts, and it needs to have high toughness. The main body of the wheel needs to have high strength and toughness, while the hardness cannot be too high, so as to avoid stress concentration and cracking at sharp corners such as keyways, affecting the overall rigidity and structural stability of the wheel.
[0003] During the entire spinning process, the extrusion pressure between the spinning wheel and the workpiece contact area is very large, up to several thousand megapascals. Both the spinning wheel and the workpiece are subjected to severe friction. The apparent quality of the working part of the spinning wheel (shape, accuracy, roughness, hardness, etc.) will also be directly reflected on the outer surface of the workpiece. Figure 2 shown.
[0004] According to statistics, for every 180-200 small and medium diameter cylindrical parts that are spun, the wheel needs to be replaced or repaired. It is necessary to select a suitable surface strengthening process to improve the comprehensive performance of the wheel surface, reduce failures, and extend the service life. The currently mature surface modification technologies include surface carburizing, surface nitriding, carbonitriding, nitrocarburizing, and QPQ technology. By strengthening the surface of the parts, improving the strength of the surface material or changing the prestress state of the surface material, the generation and development of fatigue cracks can be effectively inhibited, thereby improving the working performance and service life of the wheel.
[0005] At present, there are few studies on the surface strengthening technology of rotary wheels at home and abroad. You can refer to the surface strengthening technology of gears and the surface strengthening technology of Cr12MoV die steel. At present, advanced surface strengthening methods include laser cladding, ultrasonic rolling, and ultrasonic shot peening. Bi Yan et al., in "Research on the Wear Resistance of Composite Superhard Layer of Cr12MoV Die Steel Laser Cladding [J]. Forging Technology", 2019, 44(08), used the SKD11 powder laser cladding method to form a millimeter-level cladding layer, and then used the TD thermal diffusion method to form a micron-level superhard vanadium carbide layer on the laser cladding layer. The composite superhard layer is tightly bonded and the wear life is significantly improved.
[0006] In the paper “Research Status and Application of Ultrasonic Shot Peening Surface Strengthening Technology”, Cong Jiahui et al. summarized the influence of ultrasonic shot peening on the surface integrity, fatigue strength and corrosion resistance of materials, summarized the application status of ultrasonic shot peening, and pointed out that the process of ultrasonic shot peening technology needs to be combined with basic theory to explore the optimal process parameters for in-depth research, so as to achieve both strengthening quality and efficiency, reduce processing costs, and promote large-scale engineering applications of ultrasonic shot peening. Dai Qilong et al. conducted a theoretical analysis of the ultrasonic rolling process, established a theoretical model of the surface roughness of the sample after ultrasonic rolling, and experimentally verified the theoretical model. Secondly, the ultrasonic rolling device was used to conduct single factor test and orthogonal test of ultrasonic rolling, and the influence law and degree of each process parameter on the surface integrity were obtained. The above surface strengthening technologies are all in the stage of testing or promotion and use, with high costs and unstable process schemes.
[0007] Mature surface strengthening technologies include surface carburizing, surface nitriding, carbonitriding, nitrocarburizing, QPQ technology, etc. Carburizing of steel is to heat low-carbon steel to a high temperature in a carbon-rich medium so that active carbon atoms penetrate into the surface of the steel to obtain a high-carbon infiltration layer structure. After quenching and low-temperature tempering, the surface has high hardness, wear resistance and fatigue resistance, while the matrix still maintains sufficient strength and toughness. Similarly, nitriding of steel is a chemical heat treatment process that allows nitrogen atoms to penetrate into the surface of the steel to form a nitrogen-rich hardened layer. At present, the above technologies have been maturely applied to engineering practice, and the process methods are stable and suitable for mass customization. On this basis, the nitriding process is simultaneously carburized to promote the diffusion of nitrogen atoms, which is called nitrocarburizing. QPQ technology is a salt bath liquid nitriding technology that realizes the combination of nitriding and oxidation processes to generate a double-layer nitrided layer on the surface of the substrate, which has the characteristics of high hardness and high wear resistance. Summary of the invention
[0008] In order to overcome the shortcomings of low surface strength and short service life of a roller in the prior art, the present invention proposes a method for determining a roller surface strengthening process.
[0009] 1. A method for determining a surface strengthening process of a rotary wheel, characterized in that the specific process is:
[0010] Step 1: Prepare the test block:
[0011] There are multiple test blocks, which are divided into three test groups, namely a nitriding treatment test group, a nitrocarburizing treatment test group and a surface composite QPQ salt bath treatment test group.
[0012] The material of the test block is the same as that of the rotating wheel substrate; the surface roughness of the test block is ≤Ra0.8.
[0013] Step 2: Tests of different nitriding treatments:
[0014] Surface nitriding test, nitrocarburizing test and surface composite QPQ salt bath treatment test were carried out on the test blocks of nitriding treatment group, nitrocarburizing test and surface composite QPQ salt bath treatment group respectively. The surface strengthening process of the rotary wheel was determined by analyzing the test data.
[0015] The nitriding treatment test group was subjected to nitriding treatment. The process route of the surface nitriding treatment was preheating - heating - heat preservation - exhaust cooling, and a strengthening layer with a thickness of 9 to 12 μm was obtained.
[0016] The nitrocarburizing process route is preheating - heating - heat preservation - exhaust cooling; the nitrocarburizing layer is the strengthening layer of the test block.
[0017] The surface composite QPQ salt bath treatment process route is preheating - heating - salt bath insulation - exhaust cooling; a strengthening layer with a thickness of 5 to 8 μm is obtained.
[0018] Wherein: the process of the nitriding treatment test on the surface of the test block of the nitriding treatment test group is to heat each test block in the nitriding treatment test group to 520-550°C at a heating rate of 10-15°C / min through a heating furnace. During the heating process, nitrogen is introduced when each test block is preheated to 200°C. When the test block is heated to 520-550°C, insulation begins; the insulation time is 30h. After the insulation is completed, it is cooled to room temperature with the furnace. During the nitriding treatment, the ammonia decomposition rate of the nitrogen is 30%-50%.
[0019] The process of the nitrocarburizing treatment test on the surface of the test block of the nitrocarburizing treatment test group is to heat each test block in the nitrocarburizing treatment test group to 630-690°C at a heating rate of 10-15°C / min through a heating furnace. When the test block is heated to 630-690°C, insulation begins; the insulation time is 120-180min. After the insulation is completed, it is cooled to room temperature with the furnace to obtain a 5-6μm thick infiltration layer on the surface. During the nitrocarburizing treatment, the ammonia gas introduction amount is 200L / min, and the methanol introduction amount is 30mL / min.
[0020] During the surface composite QPQ salt bath treatment, the test blocks of the surface composite QPQ salt bath treatment test group are preheated to 200° C. Each preheated test block is placed in a nitride salt bath at 530 to 590° C. and kept warm for 60 to 120 minutes. After the end of the heat preservation, the test blocks are cooled to room temperature.
[0021] Step 3: Determine the surface strengthening method of the rotary wheel:
[0022] The surface hardness and friction and wear performance of each strengthening layer obtained by surface nitriding treatment test, nitrocarburizing treatment test and surface composite QPQ salt bath treatment test in step 2 were tested respectively. The results showed that the surface hardness of the surface nitriding process was HV1075, the friction coefficient was 0.706, and the wear loss was 0.903 / 10 6 μm 3 ; The surface hardness of the nitrocarburizing process is HV1037, the friction coefficient is 0.713, and the wear loss is 3.002 / 10 6 μm 3 ; The surface hardness of the surface composite QPQ salt bath process is HV959, the friction coefficient is 0.749, and the wear loss is 0.557 / 10 6 μm 3 .
[0023] Based on the surface hardness and friction and wear properties of each strengthening layer, the surface composite QPQ salt bath method was determined to be the rotary wheel surface strengthening method.
[0024] Step 4: Strengthening the surface of the rotating wheel:
[0025] The surface composite QPQ salt bath process is used to strengthen the surface of the rotating wheel.
[0026] According to the process of surface composite QPQ salt bath treatment described in step 2, the surface of the rotating wheel is subjected to surface composite QPQ salt bath treatment to obtain a rotating wheel with a surface reinforced treatment.
[0027] The technical problem solved by the present invention is to carry out surface strengthening research on Cr12MoV material, use QPQ technology to strengthen the surface of the rotating wheel, apply the strengthened rotating wheel to work under complex working conditions of high load, high wear resistance and contact fatigue resistance, and verify its strengthening effect.
[0028] The present invention conducts a comparative test on the strengthening effects of different surface strengthening technologies, and takes 12 test pieces of the same φ10mm×20mm material as the substrate, and the substrate hardness is HRC730-750; the specific scheme is shown in Table 1:
[0029] Table 1 Cr12MoV test block surface strengthening process test plan
[0030] Group No. Strengthening process After strengthening, the hardness is expected to reach 1 Surface nitriding ≥HV780 2 Nitrocarburizing ≥HV780 3 Surface composite QPQ salt bath treatment ≥HV780
[0031] Wear test experiments were carried out. The friction and wear tests were carried out on the above three groups of specimens on a friction and wear testing machine. The wear amount and surface hardness of each group of specimens were recorded as the load size and wear time increased. The optimal surface strengthening method was selected. The test plan is shown in Table 2.
[0032] Table 2 Cr12MoV test block wear comparison test plan
[0033] Group No. Wear time Wear 1 Surface nitriding 2 Nitrocarburizing 3 Surface composite QPQ salt bath treatment
[0034] Compared with the prior art, the present invention has the following beneficial effects:
[0035] The specimens were subjected to surface nitriding, nitrocarburizing, and surface composite QPQ salt bath treatment, respectively. Based on the research results of the process parameters of the three surface strengthening methods, see the attached Figure 3 -Attached Figure 5 , and compared and analyzed the surface hardness and friction and wear properties of the specimens under different surface strengthening systems. Through the analysis of the test data, it was concluded that the surface composite QPQ salt bath treatment had the best wear resistance, and the hardness met the requirements of the wheel working, and a wheel surface strengthening method was determined.
[0036] The composite QPQ salt bath treatment was used to strengthen the surface of the wheel, see attached Figure 6 The service life of the spinning wheel was verified on the spinning equipment, confirming that the service life of the spinning wheel after the composite QPQ salt bath treatment was increased by 10% compared with the spinning wheel without strengthening treatment. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 It is the force diagram of the contact between the rotating wheel and the workpiece.
[0038] Figure 2 It is an intuitive reflection of the wheel defects on the product surface.
[0039] Figure 3 is the influence of surface nitriding process parameters on the thickness of the nitrided layer; among them, Figure 3 a is the effect of temperature on the thickness of the carburized layer, Figure 3 b is the effect of time on the thickness of the diffusion layer.
[0040] Figure 4 is the influence of nitrocarburizing process parameters on the thickness of the carburized layer; among them, Figure 4 a is the effect of co-infiltration time on the thickness of the infiltration layer, Figure 4 b is the effect of co-infiltration temperature on the thickness of the infiltration layer.
[0041] Figure 5 It is the influence of surface composite QPQ salt bath treatment process parameters on the thickness of the diffusion layer; among them, Figure 5 a is the effect of temperature on the thickness of the carburized layer, Figure 5 b is the effect of time on the thickness of the diffusion layer.
[0042] Figure 6 It is the surface nitriding process curve.
[0043] Figure 7 It is the scanning structure of the surface nitriding layer.
[0044] Figure 8 It is the nitrocarburizing process curve.
[0045] Fig. 9 It is the scanning structure of the carburized layer after nitrogen and carbon treatment.
[0046] Fig.10 It is the process curve of surface composite QPQ salt bath treatment.
[0047] Fig.11 It is the scanning organization of the infiltration layer after surface composite QPQ salt bath treatment.
[0048] Fig.12 It is a flow chart of the present invention. DETAILED DESCRIPTION
[0049] Step 1: Prepare the test block:
[0050] The test block is made of Cr12MoV high carbon die steel, which is the same material as the wheel base. The surface roughness of the test block is ≤Ra0.8.
[0051] There are 12 test blocks, which are divided into three test groups, namely a nitriding treatment test group, a nitrocarburizing treatment test group and a surface composite QPQ salt bath treatment test group.
[0052] Step 2: Tests of different nitriding treatments:
[0053] The conventional process was used to carry out surface nitriding treatment test, nitrocarburizing treatment test and surface composite QPQ salt bath treatment test on the specimens. The surface strengthening process of the rotary wheel was determined by analyzing the test data.
[0054] The present invention performs nitriding treatment, nitrocarburizing treatment and surface composite QPQ salt bath treatment by different process parameters, specifically:
[0055] Ⅰ Nitriding treatment test
[0056] The conventional method was used to carry out nitriding treatment on the nitriding treatment test group. The process route of the surface nitriding treatment is preheating - heating - heat preservation - exhaust cooling. The specific process is:
[0057] Each test block in the nitriding treatment test group was heated to 520-550°C at a heating rate of 10-15°C / min in a heating furnace. During the heating process, nitrogen was introduced when each test block was preheated to 200°C. When the test block was heated to 520-550°C, it was kept warm for 30 hours. The surface nitriding process curve is shown in the attached figure. Figure 7 After the heat preservation is completed, the furnace is cooled to room temperature, and a 9-12μm thick infiltration layer is obtained on the surface; this infiltration layer is the strengthening layer of the test block.
[0058] During the nitriding treatment, the ammonia decomposition rate of the nitrogen gas is 30% to 50%.
[0059] The SEM images show that the infiltration layer is densely bonded. Figure 8 The bright white layer on the surface of the test block in the figure is the strengthening layer.
[0060] Ⅱ Nitrocarburizing treatment
[0061] The nitrocarburizing process route is preheating - heating - heat preservation - exhaust cooling. The specific process is:
[0062] Each test block in the nitrocarburizing treatment test group is heated to 630-690℃ by a heating furnace at a heating rate of 10-15℃ / min. When the test block is heated to 630-690℃, it is kept warm; the holding time is 120-180min. The nitrocarburizing process curve is shown in the attached Fig. 9 After the heat preservation is completed, the furnace is cooled to room temperature, and a 5-6μm thick infiltration layer is obtained on the surface; this infiltration layer is the strengthening layer of the test block.
[0063] During the nitrocarburizing treatment, the ammonia gas flow rate was 200 L / min and the methanol flow rate was 30 mL / min.
[0064] The SEM images show that the infiltration layer is densely bonded. Fig.10 The bright white layer on the surface of the test block in the figure is the strengthening layer.
[0065] ⅢSurface composite QPQ salt bath treatment
[0066] The conventional process is used to treat each test block in the surface composite QPQ salt bath treatment test group with a surface composite QPQ salt bath. The surface composite QPQ salt bath treatment process route is preheating - heating - salt bath insulation - exhaust cooling, and the specific process is:
[0067] Preheat each test block to 200℃. Place each preheated test block in a nitride salt bath at 530~590℃ and keep warm for 60~120min. See the attached process curve for the surface composite QPQ salt bath treatment. Fig.11 After the heat preservation is completed, the material is cooled to room temperature to obtain a diffusion layer with a thickness of 5 to 8 μm, i.e., a strengthening layer.
[0068] Scanning electron microscopy showed that the infiltration layer was densely bonded. Fig.12 The bright white layer on the surface of the test block is the strengthening layer.
[0069] Table 3 Process parameters of each embodiment in step 2
[0070]
[0071]
[0072] Step 3: Determine the best surface enhancement method:
[0073] The surface hardness and friction and wear performance of the strengthening layers obtained by different processes in step 2 were tested according to the conventional method. The surface hardness of the surface nitriding process was HV1075, the friction coefficient was 0.706, and the wear loss was 0.903 / 10 6 μm 3 ; The surface hardness of the nitrocarburizing process is HV1037, the friction coefficient is 0.713, and the wear loss is 3.002 / 10 6 μm 3 ; The surface hardness of the surface composite QPQ salt bath process is HV959, the friction coefficient is 0.749, and the wear loss is 0.557 / 10 6 μm 3 .
[0074] The test results show that the three strengthening schemes of surface nitriding process, nitrocarburizing process and surface composite QPQ salt bath process all meet the hardness requirements of the rotating wheel.
[0075] The wear performance analysis results show that the surface composite QPQ salt bath process has the best wear resistance, followed by surface nitriding, and nitrocarburizing has poor wear resistance.
[0076] The surface hardness and friction and wear properties of each strengthening layer determine that the surface composite QPQ salt bath process has the best comprehensive performance.
[0077] Table 4 Surface hardness of the sample infiltration layer under different process conditions
[0078] Group No. Strengthening process After strengthening, the hardness is 1 Surface nitriding HV1075 2 Nitrocarburizing HV1037 3 QPQ Technology HV959
[0079] Table 5 Friction and wear properties of samples under different process conditions
[0080] Group No. Wear time Friction coefficient <![CDATA[Wear amount ( / 10 6 μm 3 )]]> 1 Surface nitriding 0.706 0.903 2 Nitrocarburizing 0.713 3.002 3 QPQ Technology 0.749 0.577
[0081] Step 4: Strengthening the surface of the rotating wheel:
[0082] The surface of the wheel is strengthened by using the surface composite QPQ salt bath process.
[0083] According to the process of surface composite QPQ salt bath treatment described in step 2, the surface of the rotating wheel is subjected to surface composite QPQ salt bath treatment using conventional technology.
[0084] The surface composite QPQ salt bath treatment process route is preheating - heating - salt bath insulation - exhaust cooling, the specific process is:
[0085] Preheat each test block to 200℃. Place each preheated test block in a nitride salt bath at 530-590℃ and keep it warm for 60-120min. After the insulation, cool it to room temperature to obtain a 5-8μm thick infiltration layer, i.e., a strengthening layer. The surface of the wheel with strengthening treatment is obtained.
[0086] To verify the effect of the present invention, the surface of the rotary wheel with enhanced treatment was tested and verified. The verification results show that the coating of the rotary wheel with enhanced treatment fell off after processing 220 workpieces, and its service life was increased by 10% compared with the rotary wheel without enhanced treatment.
[0087] Table 6 Relationship between processing quantity and wheel surface hardness
[0088]
[0089] Table 7 Relationship between processing quantity and wear of roller fillet
[0090]
Claims
1. A method for determining a surface strengthening process of a rotary wheel, characterized in that: The specific process is: Step 1: Prepare the test block: There are multiple test blocks, which are divided into three test groups, namely, a nitriding treatment test group, a nitrocarburizing treatment test group and a surface composite QPQ salt bath treatment test group; Step 2: Tests of different nitriding treatments: Surface nitriding treatment test, nitrocarburizing treatment test and surface composite QPQ salt bath treatment test were carried out on the test blocks of the nitriding treatment test group, the nitrocarburizing treatment test group and the surface composite QPQ salt bath treatment test group respectively; the surface strengthening process of the rotary wheel was determined by analyzing the test data; The nitriding treatment test group was subjected to nitriding treatment; the process route of the surface nitriding treatment was preheating - heating - heat preservation - exhaust cooling, and a strengthening layer with a thickness of 9 to 12 μm was obtained; The nitrocarburizing process route is preheating - heating - heat preservation - exhaust cooling; the nitrocarburizing layer is the strengthening layer of the test block; The surface composite QPQ salt bath treatment process route is preheating - heating - salt bath insulation - exhaust cooling; a strengthening layer with a thickness of 5 to 8 μm is obtained; Step 3: Determine the surface strengthening method of the rotary wheel: The surface hardness and friction and wear performance of each strengthening layer obtained by surface nitriding treatment test, nitrocarburizing treatment test and surface composite QPQ salt bath treatment test in step 2 were tested respectively. The results showed that the surface hardness of the surface nitriding process was HV1075, the friction coefficient was 0.706, and the wear loss was 0.903 / 10 6 μm 3 ; The surface hardness of the nitrocarburizing process is HV1037, the friction coefficient is 0.713, and the wear loss is 3.002 / 10 6 μm 3 ; The surface hardness of the surface composite QPQ salt bath process is HV959, the friction coefficient is 0.749, and the wear loss is 0.557 / 10 6 μm 3 ; Based on the surface hardness and friction and wear properties of each strengthening layer, the surface composite QPQ salt bath method was determined to be the wheel surface strengthening method; Step 4: Strengthening the surface of the rotating wheel: The surface of the rotating wheel is strengthened by using the surface composite QPQ salt bath process; Specifically: According to the process of surface composite QPQ salt bath treatment described in step 2, the surface of the rotating wheel is subjected to surface composite QPQ salt bath treatment to obtain a rotating wheel with a surface reinforced treatment.
2. The method for determining the surface strengthening process of a rotary wheel according to claim 1, characterized in that: The material of the test block is the same as that of the rotating wheel substrate; the surface roughness of the test block is ≤Ra0.
8.
3. The method for determining the surface strengthening process of a rotary wheel according to claim 1, characterized in that: The process of the surface nitriding treatment test of the test blocks of the nitriding treatment test group in step 2 is to heat each test block in the nitriding treatment test group to 520-550°C at a heating rate of 10-15°C / min through a heating furnace; during the heating process, nitrogen is introduced when each test block is preheated to 200°C; when the test block is heated to 520-550°C, insulation is started; the insulation time is 30h; after the insulation is completed, it is cooled to room temperature with the furnace.
4. The method for determining the surface strengthening process of a rotary wheel according to claim 3, characterized in that: In the nitriding treatment, the ammonia decomposition rate of nitrogen is 30% to 50%.
5. The method for determining the surface strengthening process of a rotary wheel according to claim 1, characterized in that: The process of the nitrocarburizing treatment test on the surface of the test block of the nitrocarburizing treatment test group in step 2 is to heat each test block in the nitrocarburizing treatment test group to 630-690°C at a heating rate of 10-15°C / min through a heating furnace; start to keep the test block warm after it is heated to 630-690°C; the keeping time is 120-180min; after the keeping is completed, cool it to room temperature with the furnace to obtain a 5-6μm thick infiltration layer on the surface.
6. The method for determining the surface strengthening process of a rotary wheel according to claim 5, characterized in that: During the nitrocarburizing treatment, the ammonia gas flow rate was 200 L / min and the methanol flow rate was 30 mL / min.
7. The method for determining the surface strengthening process of a rotary wheel according to claim 1, characterized in that: In step 2, when performing the surface composite QPQ salt bath treatment, the test blocks of the surface composite QPQ salt bath treatment test group are preheated to 200° C.; each preheated test block is placed in a nitride salt bath at 530 to 590° C. and kept warm for 60 to 120 minutes; and cooled to room temperature after the insulation is completed.