Preparation method of composite rail grinding wheel

Abstract

The invention discloses a preparation method of a composite rail grinding wheel, which comprises the following steps: S1. preparing composite abrasive particles; S2. mixing 36.8-62.3wt% of zirconium corundum abrasive, 13.3-32.7wt% of composite abrasive particles and 7.6-11.6wt% of composite aerogel, adding 1-3.5wt% of a wetting agent, and then adding 15.6-31.3wt% of a binder, and mixing uniformly to obtain a mixed abrasive; S3. hot-pressing the obtained mixed abrasive to produce a grinding wheel blank; S4. winding the grinding wheel blank with wire for reinforcement, drying and hardening the blank, and producing a finished composite superhard grinding wheel. The grinding wheel can maintain good sharpness and good wear resistance after long-term operation, and the composite aerogel can quickly discharge grinding heat generated by the grinding wheel, thereby improving grinding efficiency and reducing the blueing phenomenon of rail burn. The repaired rail has a high surface finish and a more delicate surface.

Description

Technical Field

[0001] The invention relates to the technical field of grinding wheels, and in particular to a preparation method of a composite rail grinding wheel. Background Art

[0002] Rail grinding is used for grinding rail welded joints and various point rails and switches. Rail grinding can reduce the noise when the train runs along the rails, reduce the vibration level and eliminate the wavy wear of the rails on curves.

[0003] As the number of railway lines continues to increase and the efficiency of railway transportation improves year by year, the workload of rail maintenance and grinding is also growing. The grinding wheels used in rail grinding vehicles currently have poor grip on the abrasive, resulting in a short grinding service life of the grinding wheels. At the same time, the grinding wheels grind at high speed and heavy load, and the grinding surface has become passivated, resulting in a blunt cutting edge. The high grinding heat generated cannot be quickly conducted away, resulting in poor surface finish of the rail grinding and accompanied by a bluing phenomenon. In addition, the widely used resin-bonded corundum abrasive grinding wheels are prone to generating a large amount of dust during the grinding process due to the bond.

[0004] Therefore, new performance requirements are constantly being put forward for the grinding wheels required for rail grinding vehicles. It is hoped that there will be a new type of grinding wheel with at least one of the following characteristics: no burning of the rails during the grinding process, fine roughness; strong grinding ability for the rails; better wear resistance and long service life; environmental protection, no sulfur-containing smoke emissions.

[0005] Based on the above-mentioned defects of the prior art, it is necessary to study a composite rail grinding wheel. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for preparing a composite rail grinding wheel to improve the grinding performance of the grinding wheel on the rail, improve the grinding efficiency, improve the glossiness of the polished surface and extend the service life of the grinding wheel.

[0007] In view of this, the solution of the present invention is:

[0008] A method for preparing a composite rail grinding wheel comprises the following steps:

[0009] S1. Preparation of composite abrasive particles;

[0010] S2 36.8-62.3wt% zirconium corundum abrasive, 13.3-32.7wt% composite abrasive particles and 7.6-11.6wt% composite aerogel was mixed and 1-3.5wt% wetting agent was added, and then 15.6-31.3wt% binder was added and mixed to obtain a mixed abrasive;

[0011] S3. The resulting mixed abrasive is hot pressed to produce a grinding wheel blank;

[0012] S4. The grinding wheel blank is reinforced by winding wire and then dried and hardened to produce a finished composite super-hard grinding wheel.

[0013] In one embodiment, the preparation method of the composite abrasive particles in step S1 is as follows: 20-57 wt% silicon carbide, 30-67 wt% blue corundum, and 8-37 wt% cubic boron carbide are mixed and stirred, a forming agent is added, the mixture is dried, and then heated and fused, and then crushed to obtain the composite abrasive particles.

[0014] Furthermore, the composite abrasive particles have a particle size of 24-60 mesh.

[0015] Furthermore, the smelting process is carried out at a temperature of 950-1080° C. for 0.5-1 h.

[0016] Furthermore, the forming agent is at least one of a polyvinyl alcohol aqueous solution and a vinyl acetate-ethylene copolymer emulsion.

[0017] In one embodiment, the composite aerogel is Ni / Al2O3-TiO2 aerogel.

[0018] In one embodiment, the binder is a reinforced high-temperature modified polyimide resin.

[0019] In one embodiment, the zirconium corundum abrasive has a particle size of 14-20 mesh.

[0020] In one embodiment, the step S3 is hot pressing at 160-180° C. for 50-70 minutes.

[0021] In one embodiment, the step S4 is performed by hardening in a hardening furnace at 170-200° C. for 28-35 hours.

[0022] Compared with the prior art, the present invention has the following effects:

[0023] 1. The preparation method provided by the present invention combines superhard composite wear-resistant particles with abrasives. By adding composite aerogel, the composite superhard grinding wheel can maintain good sharpness and good wear resistance under long-term working conditions. At the same time, the composite aerogel can quickly discharge the grinding heat generated by the grinding wheel, improve grinding efficiency, reduce the blueing phenomenon of rail burns, and the surface of the repaired rail is high in finish and more delicate.

[0024] 2. The present invention fuses three abrasive particles of silicon carbide, blue corundum and cubic boron carbide and then mixes them with zirconium corundum abrasive. The purpose is to make the expansion coefficient of the prefabricated abrasive particles close to that of zirconium corundum abrasive, and then control a reasonable friction coefficient by particle size to improve the overall performance of the grinding wheel.

[0025] 3. The present invention improves the density and bonding strength of the grinding wheel and reduces the inherent stress of the grinding wheel by combining enhanced high-temperature modified polyimide resin with composite superhard abrasives. It can resist high temperature damage to the grinding wheel when grinding rails. The grinding wheel has good stability and wear resistance and produces little dust. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and beneficial technical effects of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described in this specification are only for the purpose of explaining the present invention and are not intended to limit the present invention.

[0027] In a specific embodiment of the present invention, a method for preparing a composite rail grinding wheel is provided, comprising the following steps:

[0028] S1. Preparation of composite abrasive particles: 20-57wt% silicon carbide, 30-67wt% blue corundum, 8-37wt% cubic boron carbide powder mixture was mixed and stirred, a forming agent was added and dried and fused at 950-1080 ° C for 0.5-1h, and then crushed to obtain composite abrasive particles;

[0029] S2 36.8-62.3wt% zirconium corundum abrasive, 13.3-32.7wt% composite abrasive particles and 7.6-11.6wt% Ni / Al2O3-TiO2 composite aerogel mixed, adding 1-3.5wt% wetting agent, and then adding 15.6-31.3wt% of enhanced high-temperature modified polyimide resin as a binder, mixed to obtain a mixed abrasive;

[0030] S3 the resulting mixed abrasive was hot pressed at 160-180 ℃ 50-70min molding, production of grinding wheel blank;

[0031] S4. After the grinding wheel blank is reinforced by winding wire, it is hardened in a hardening furnace at 170-200℃ for 28-35 hours to produce a finished composite super-hard grinding wheel.

[0032] In a preferred embodiment, the particle size of the composite abrasive particles in step S1 is preferably in the range of 24-60 mesh, and the density after mixing is in the range of 1.36-2.68 g / cm 3 ; The zirconium corundum abrasive particle size range in step S2 is 14-20 mesh; the selection of the above-mentioned composite abrasive particles - zirconium corundum abrasive particle size forms a primary and secondary relationship, which helps to improve the grinding efficiency.

[0033] In a preferred embodiment, the forming agent is at least one of a polyvinyl alcohol aqueous solution and a vinyl acetate-ethylene copolymer emulsion; and the wetting agent is preferably furfural.

[0034] The manufacturing process described in this invention involves subjecting a superhard, wear-resistant abrasive particle mixture of silicon carbide, blued corundum, and cubic boron carbide to a special sintering process. This process produces an expansion coefficient close to that of zirconium corundum, and, through controlled particle size, exhibits a good surface friction coefficient. Combined with a reinforced, high-temperature modified polyimide resin, the resulting abrasive has high binding properties, high hardness, excellent self-sharpening properties, and is resistant to shedding. It also exhibits strong heat resistance and chemical stability, making it less susceptible to chemical reactions. The composite aerogel material added to the mix features a nanoscale porous, three-dimensional network structure with an extremely low density, high specific surface area, and high porosity. This creates micropores between the abrasive particles, providing excellent heat dissipation. This allows the composite superhard grinding wheel to maintain excellent sharpness and wear resistance even during extended operation. Furthermore, the innovative pore-forming technology rapidly dissipates grinding heat generated by the wheel, improving grinding efficiency and reducing the bluing phenomenon associated with rail burns. The repaired rails exhibit a smoother, more refined surface finish. By combining modified polyimide resin with composite super-hard abrasive, the bonding strength of the grinding wheel abrasive is improved, the inherent stress of the grinding wheel is reduced, and the grinding wheel can resist damage to the grinding wheel caused by high temperature when grinding rails. The grinding wheel has good stability and wear resistance.

[0035] Example 1

[0036] 1) Preparation of composite abrasive particles: 20 kg of silicon carbide, 67 kg of blue corundum, and 13 kg of cubic boron carbide powder were mixed and stirred, 4.6 kg of polyvinyl alcohol aqueous solution was added, and the mixture was dried at 80°C for 2 h, then melted at 1080°C for 0.5 h, and then crushed to obtain composite abrasive particles of 24-60 mesh;

[0037] 2) Mixed abrasive: 36.8 kg of zirconium corundum abrasive (14-20 mesh), 32.7 kg of composite abrasive particles and 7.6 kg of Ni / Al2O3-TiO2 composite aerogel were mixed, 1 kg of furfural was added, and 21.9 kg of enhanced high-temperature modified polyimide resin was added as a binder, and mixed to obtain a mixed abrasive;

[0038] 3) hot pressing the obtained mixed abrasive at 175° C. for 55 minutes to form a grinding wheel blank;

[0039] 4) After the grinding wheel blank is reinforced with wire wrapping, it is hardened in a hardening furnace at 180°C for 30 hours to produce a finished composite super-hard grinding wheel.

[0040] Example 2

[0041] 1) Preparation of composite abrasive particles: 57 kg of silicon carbide, 30 kg of blue corundum, and 13 kg of cubic boron carbide powder were mixed and stirred, 4.6 kg of vinyl acetate-ethylene copolymer emulsion was added, and the mixture was dried at 90°C for 1.5 hours, then melted at 950°C for 1 hour, and then crushed to obtain composite abrasive particles of 24-60 mesh;

[0042] 2) Mixed abrasive: 62.3 kg of zirconium corundum abrasive (14-20 mesh), 13.3 kg of composite abrasive particles and 7.8 kg of Ni / Al2O3-TiO2 composite aerogel were mixed, 1 kg of furfural was added, and 15.6 kg of enhanced high-temperature modified polyimide resin was added as a binder, and the mixture was mixed to obtain a mixed abrasive;

[0043] 3) hot pressing the obtained mixed abrasive at 160° C. for 70 minutes to form a grinding wheel blank;

[0044] 4) After the grinding wheel blank is reinforced with wire wrapping, it is hardened in a hardening furnace at 200°C for 28 hours to produce a finished composite super-hard grinding wheel.

[0045] Example 3

[0046] 1) Preparation of composite abrasive particles: 33 kg of silicon carbide, 30 kg of blue corundum, and 37 kg of cubic boron carbide powder were mixed and stirred, 4.6 kg of vinyl acetate-ethylene copolymer emulsion was added, and the mixture was dried at 90°C for 1.5 h, then melted at 1000°C for 0.8 h, and then crushed to obtain composite abrasive particles of 24-60 mesh;

[0047] 2) Mixed abrasive: 40 kg of zirconium corundum abrasive (14-20 mesh), 24 kg of composite abrasive particles and 11.6 kg of Ni / Al2O3-TiO2 composite aerogel were mixed, 3.5 kg of furfural was added, and 20.9 kg of enhanced high-temperature modified polyimide resin was added as a binder, and the mixture was mixed to obtain a mixed abrasive;

[0048] 5) hot pressing the obtained mixed abrasive at 180° C. for 50 minutes to form a grinding wheel blank;

[0049] 6) After the grinding wheel blank is reinforced with wire wrapping, it is hardened in a hardening furnace at 180°C for 30 hours to produce a finished composite super-hard grinding wheel.

[0050] Example 4

[0051] 1) Preparation of composite abrasive particles: 30 kg of silicon carbide, 62 kg of blue corundum, and 8 kg of cubic boron carbide powder were mixed and stirred, 4.6 kg of a mixture of polyvinyl alcohol in water and vinyl acetate-ethylene copolymer emulsion was added, and the mixture was dried at 90°C for 1.5 h, then melted at 1080°C for 0.5 h, and then crushed to obtain composite abrasive particles of 24-60 mesh;

[0052] 2) Mixed abrasive: 40 kg of zirconium corundum abrasive (14-20 mesh), 18 kg of composite abrasive particles and 9 kg of Ni / Al2O3-TiO2 composite aerogel were mixed, 1.7 kg of furfural was added, and 31.3 kg of enhanced high-temperature modified polyimide resin was added as a binder, and the mixture was mixed to obtain a mixed abrasive;

[0053] 3) hot pressing the obtained mixed abrasive at 170° C. for 60 minutes to form a grinding wheel blank;

[0054] 4) After the grinding wheel blank is reinforced with wire wrapping, it is hardened in a hardening furnace at 170°C for 35 hours to produce a finished composite super-hard grinding wheel.

[0055] Comparative Example 1

[0056] In step 3), no Ni / Al2O3-TiO2 composite aerogel is added, and the proportions and other steps are the same as in Example 1.

[0057] Comparative Example 2

[0058] In step 3), 5 kg of Ni / Al2O3-TiO2 composite aerogel was added, and the proportions and other steps were the same as those in Example 1.

[0059] Comparative Example 3

[0060] In step 3), 15 kg of Ni / Al2O3-TiO2 composite aerogel was added, and the proportions and other steps were the same as those in Example 1.

[0061] Comparative Example 4

[0062] In step 1), 65-80 mesh composite abrasive particles are crushed and taken, and in step 3), 25-40 mesh zirconium corundum abrasive is taken. The proportions and other steps are the same as those in Example 2.

[0063] Comparative Example 5

[0064] In step 1), 14-20 mesh composite abrasive particles are crushed and prepared, and the proportions and other steps are the same as those in Example 2.

[0065] Comparative Example 6

[0066] In step 2), phenolic resin 2150 is used as a binder, and the proportions and other steps are the same as those in Example 2.

[0067] Comparative Example 7

[0068] In step 1), only 100 kg of silicon carbide is used, and other proportions and steps are the same as those in Example 3.

[0069] Comparative Example 8

[0070] In step 1), only 100 kg of blue corundum was used, and other proportions and steps were the same as those in Example 3.

[0071] Comparative Example 9

[0072] In step 1), only 100 kg of cubic boron carbide is used, and other proportions and steps are the same as those in Example 3.

[0073] Comparative Example 10

[0074] In step 1), 55 kg of silicon carbide and 45 kg of blue corundum were used, and the proportions and other steps were the same as those in Example 3.

[0075] Comparative Example 11

[0076] In step 1), 65 kg of blue corundum and 35 kg of cubic boron carbide were used, and the proportions and other steps were the same as those in Example 3.

[0077] Comparative Example 12

[0078] In step 1), 65 kg of silicon carbide and 35 kg of cubic boron carbide are used, and the proportions and other steps are the same as those in Example 3.

[0079] Experimental example

[0080] A CNC grinder was used to simulate a rail operation process. Grinding wheels (same specifications) prepared in Examples 1-4 and Comparative Examples 1-6 were tested for wheel wear, friction coefficient, and surface roughness. The wear of the rails and the surface roughness of the rails after grinding were also tested. The test conditions were: rail workpiece speed of 10.8 km / h, grinding power of 8 kW, grinding time of 15 minutes, and grinding wheel speed of 2400 rpm. The results are shown in Table 1.

[0081] Table 1:

[0082]

[0083] Among them, the parts marked with * are the cases where the rails of comparative examples 1, 4 and 6 are blued after grinding.

[0084] As can be seen from Table 1, in the preferred embodiments 1-4, the grinding wheels prepared exhibit excellent performance in terms of self-wear, rail grinding ability, and surface roughness of the rail after grinding. Comparative Example 1 does not contain any additives, while Comparative Example 2 adds a small amount of Ni / Al2O3-TiO2 composite aerogel. The grinding wheel wear increases, the rail wear decreases, and the rail roughness after grinding decreases. This may be because when the amount of composite aerogel is reduced, the amount of pores formed decreases, and a large amount of heat is generated during the grinding process, thereby increasing the wear of the grinding wheel. Due to self-wear, the amount of grinding powder generated increases, which affects the grinding ability of the rail. In addition, in Comparative Example 1, the heat cannot be dissipated, resulting in bluing. In Comparative Example 3, the amount of composite aerogel is increased, but the relevant performance is significantly improved. From this, it can be determined that the preferred dosage range in Examples 1-4 is used. Comparative Example 4 uses a mixture of composite abrasive particles with larger particle size and zirconium corundum. The friction coefficient after forming is larger, which affects the roughness of the rail after grinding and causes bluing. In Comparative Example 5, a mixture of composite abrasive particles with smaller particle size and zirconium corundum is used. The friction coefficient after molding is too small, affecting the grinding efficiency of the grinding wheel. Comparative Example 6 uses the existing commonly used phenolic resin as a binder. The wear of the grinding wheel itself becomes larger and the grinding efficiency of the rail is reduced, and blueing occurs. The possible reason is that the phenolic resin has poor binding properties for the abrasive particles and the inherent stress of the grinding wheel is large, which affects the wear resistance and stability of the grinding wheel. The corresponding composite abrasive particles in Comparative Examples 7-9 and Comparative Examples 10-12 respectively have significantly reduced performance under the conditions of single components and two components mixing. The possible reason is that in the absence of one or two components, the expansion coefficient of the prefabricated abrasive particles is quite different from that of the zirconium corundum, so a good synergistic grinding effect cannot be produced.

[0085] Comprehensive calculations show that existing commercially available grinding wheels can grind a single piece for 50-60 passes per kilometer, while the superhard composite grinding wheel prepared in Examples 1-4 can grind a single piece for 120-150 passes per kilometer. To eliminate common rail defects, a typical grinding wheel requires 4-6 passes, while the superhard composite grinding wheel prepared in Examples 1-4 only requires 2-3 passes.

[0086] The present invention is not limited to the schemes and principles described in the specification and implementation modes. Therefore, other effects and alternative schemes can be easily realized by those familiar with the art. Therefore, without departing from the spirit and scope of the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details, representative data and examples shown and described herein.

Claims

1. A method for preparing a composite rail grinding wheel, characterized in that: The steps include: S1 preparation of composite abrasive particles: 20-57wt% silicon carbide, 30-67wt% burned blue corundum, 8-37wt% cubic boron carbide powder mixture was mixed and stirred, a forming agent was added and dried and then heated and fused, and then crushed to obtain a particle size of 24-60 mesh composite abrasive particles; The smelting process is carried out at a temperature of 950-1080°C for 0.5-1h; The forming agent is at least one of a polyvinyl alcohol aqueous solution and a vinyl acetate-ethylene copolymer emulsion; S2 36.8-62.3wt% zirconium corundum abrasive, 13.3-32.7wt% composite abrasive particles and 7.6-11.6wt% composite aerogel was mixed and 1-3.5wt% wetting agent was added, followed by adding 15.6-31.3wt% binder, and mixed to obtain a mixed abrasive; the composite aerogel is Ni / Al2O3-TiO2 aerogel; S3. The resulting mixed abrasive is hot pressed to produce a grinding wheel blank; S4. The grinding wheel blank is reinforced by winding wire and then dried and hardened to produce a finished composite super-hard grinding wheel.

2. The preparation method according to claim 1, characterized in that The binder is a reinforced high-temperature modified polyimide resin.

3. The preparation method according to claim 1, characterized in that The particle size of the zirconium corundum abrasive is 14-20 meshes.

4. The preparation method according to claim 1, characterized in that The step S3 is hot pressing at 160-180° C. for 50-70 minutes.

5. The preparation method according to claim 1, characterized in that In step S4, the steel is hardened in a hardening furnace at 170-200° C. for 28-35 hours.

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