Low-heat efficient resin-based grinding wheel for railway steel rail grinding and manufacturing method of low-heat efficient resin-based grinding wheel

Abstract

The invention discloses a low-heat efficient resin-based grinding wheel for railway steel rail grinding and a manufacturing method of the low-heat efficient resin-based grinding wheel, and belongs to the technical field of tools for grinding, polishing or cutter grinding. The low-heat efficient resin-based grinding wheel is prepared from the following raw materials in parts by mass: 110 to 140 parts of grinding material, 15 to 25 parts of resin adhesive, 15 to 25 parts of functional filler, 18 to 25 parts of self-lubricating pore-forming filler and 3 to 5 parts of wetting agent. Wherein the self-lubricating pore-forming filler has certain hardness and strength at normal temperature, the shape and size of the self-lubricating pore-forming filler can be kept in the grinding wheel pressing process, the components of the pore-forming material are decomposed in the grinding wheel firing and hardening process, so that regular pores with certain sizes are reserved in the grinding wheel, and the self-lubricating components are released through the pores. The steel rail grinding fluid has good grinding performance and anti-burning performance, the grinding amount and efficiency are stable, grinding cracks on the surface of a ground steel rail are straight and clear, the grinding surface is not obviously burnt, the steel rail grinding fluid can be qualified for steel rail grinding repair and profile correction work, and the steel rail grinding fluid has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of tools for grinding, polishing or edge grinding, and particularly relates to a low-heat and high-efficiency resin-based grinding wheel for railway rail grinding and a manufacturing method thereof. Background Art

[0002] With the continuous expansion of the railway transportation network and the increase in the train operation speed, higher requirements are put forward for the quality and grinding processing efficiency of railway rails. The material of railway rails has high strength, high hardness and good toughness, which makes its grinding processing difficult.

[0003] In recent years, certain progress has been made in the domestic railway rail grinding technology, but there are still some problems. For example, although some grinding wheels have relatively low prices, their grinding efficiency and grinding accuracy often cannot compare with imported products. At the same time, the surface of the rail after grinding is severely burned, resulting in the surface of the rail not meeting the requirements for railway rail repair after grinding, which not only increases the operation cost, but also affects the operation efficiency and safety. In addition, most of the existing grinding wheel formulas and preparation processes also follow traditional methods, lacking innovation and breakthroughs, and it is difficult to meet the high-efficiency and high-quality requirements of railway rail grinding processing.

[0004] In the Chinese invention patent with the publication number CN116038582A, the applicant's R & D team provided a self-lubricating composite filler for resin-based grinding wheels and its preparation method. The self-lubricating composite filler includes a binder, a reinforcing filler, a lubricant, and a fiber material. The binder includes a liquid resin binder and a powder resin binder. During its preparation process, first, each raw material is dried, and the reinforcing filler, lubricant, and fiber material are subjected to surface modification treatment, and then each raw material is mixed. For the liquid resin binder, it is directly stirred and mixed evenly to obtain a mixture to be cured; for the powder resin binder, each raw material is mixed and ball-milled to obtain a mixture to be cured; the mixture to be cured is cured and formed under corresponding curing conditions to obtain a formed block material, which is crushed and sieved to obtain filler particles, and then subjected to coupling modification and / or surface metal layer plating treatment to obtain the self-lubricating composite filler. This invention is used as a filler to prepare grinding wheels, which can play a role in lubrication and friction reduction, thereby reducing the grinding temperature, improving the surface quality of workpieces, and extending the service life of grinding wheels. In addition, in the Chinese invention patent with the publication number CN115741506A, the applicant's R & D team also disclosed a resin-based self-lubricating grinding wheel with high strength and low burn and its preparation method. The resin-based self-lubricating grinding wheel includes a resin binder, a wetting agent, a functional filler, reinforcing fibers, a self-lubricating powder, a self-lubricating composite filler, and abrasives. Its preparation method is that first, each raw material is dried, and the functional filler, reinforcing fibers, self-lubricating powder, and abrasives are subjected to surface modification treatment, and then each raw material is mixed. The self-lubricating composite filler is a prefabricated composite material composed of a resin binder, a reinforcing filler, a lubricant, a fiber material, etc. The formed material after mixing each raw material is successively subjected to pre-pressing and curing to obtain a resin-based self-lubricating grinding wheel with high strength and low burn. The resin-based self-lubricating grinding wheel prepared by this invention has high mechanical properties, and at the same time, the self-lubricating component can be released at the grinding wheel / workpiece interface during the operation of the grinding wheel, which can play a role in lubrication and friction reduction, thereby reducing the grinding temperature, improving the surface quality of workpieces, and extending the service life of grinding wheels.

[0005] In the above solutions, the inventors found that the method of often using fiber fillers as reinforcing agents to "anchor" the resin matrix through fiber fillers with a high aspect ratio to improve the strength of the resin matrix fails to solve the problems that solid lubricating materials are prone to stacking, difficult to disperse, and the flaky structure is prone to slipping at high concentrations, and it is difficult for the matrix material to withstand a higher content of solid self-lubricating materials. In addition, the shape and strength of the self-lubricating material are easily affected by the processing technology, and the bonding strength between its filler particles and the resin matrix still has a high optimization space. It is necessary to further solve the influence of problems such as easy stacking, difficult dispersion, and easy slipping of the flaky structure of high-content solid lubricants on the performance of grinding wheels, and minimize the influence of solid self-lubricating components on the matrix material.

[0006] In summary, a low-heat and high-efficiency resin-based grinding wheel for railway rail grinding and its manufacturing method are proposed. By optimizing the formula and preparation process, the grinding efficiency, machining accuracy of the grinding wheel are improved, the rail grinding burn is reduced, the production cost is lowered, meeting the high requirements of railway rail grinding processing, which is of great significance to the field of railway construction engineering. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a low-heat and high-efficiency resin-based grinding wheel with high grinding efficiency, low heat generation and good grinding quality is provided. In parts by mass, its raw materials include: 110 - 140 parts of abrasive, 15 - 25 parts of resin binder, 15 - 25 parts of functional filler, 18 - 25 parts of self-lubricating pore-forming filler, and 3 - 5 parts of wetting agent.

[0008] Preferably, the abrasive includes 35 - 40 parts of brown fused alumina, 60 - 80 parts of zirconium corundum, and 15 - 20 parts of cubic boron nitride.

[0009] Preferably, the resin binder includes phenolic resin powder.

[0010] In the low-heat and high-efficiency resin-based grinding wheel, the resin binder is used to bond the functional filler, abrasive, and self-lubricating pore-forming particles, and endows the grinding wheel with mechanical properties that meet the application indicators.

[0011] Preferably, the functional filler includes 5 - 10 parts of precipitated barium sulfate, 3 - 5 parts of cryolite, 5 - 7 parts of pyrite powder, and 2 - 3 parts of feldspar powder.

[0012] Preferably, the self-lubricating pore-forming filler is a polymethyl methacrylate graphite tungsten sulfide composite filler; its components include a pore-forming component, a self-lubricating component, a binder, and aramid fiber; among them, the pore-forming component is polymethyl methacrylate, the self-lubricating component is flake graphite powder and tungsten sulfide powder, the binder is epoxy resin, and the reinforcing component is aramid fiber.

[0013] Further preferably, the preparation method of the polymethyl methacrylate graphite tungsten sulfide composite filler includes the following steps: Using epoxy resin liquid as the binder, wrap polymethyl methacrylate as the pore-forming component and graphite powder and tungsten sulfide powder as the self-lubricating components, add aramid fiber to enhance the adhesion ability of epoxy resin to polymethyl methacrylate, graphite, and tungsten sulfide. After curing and forming, through crushing and sieving, the polymethyl methacrylate graphite tungsten sulfide composite filler is obtained.

[0014] Further preferably, in the polymethyl methacrylate graphite tungsten sulfide composite filler, in parts by mass, the proportion of each component is 30 - 40 parts of epoxy resin, 4 - 8 parts of aramid fiber, 30 - 40 parts of polymethyl methacrylate, 6 - 12 parts of graphite powder, and 4 - 8 parts of tungsten sulfide.

[0015] The self-lubricating pore-forming filler has a certain hardness and strength at room temperature, can maintain its own shape and size during the grinding wheel pressing process, and the pore-forming material components decompose during the hardening process of the grinding wheel firing, leaving regular pores of a certain size in the grinding wheel, and the self-lubricating components are released through the pores.

[0016] Tungsten sulfide material has high strength and stability within its layers, can withstand large loads without being easily damaged, so it can still maintain good lubrication performance under high-pressure or heavy-load conditions and is suitable for lubrication under high-force actions such as rail grinding. Tungsten sulfide can form a protective transfer film during the friction process, effectively reducing the direct wear of the material, thereby extending the service life of the friction pair. For high-speed grinding wheels, their operating environment is characterized by high load, high rotational speed, and high feed speed, so there are relatively high requirements for the compressive properties of the grinding materials. Therefore, tungsten sulfide material with better compressive properties is selected. Through experimental research, it is found that graphite self-lubricating materials are significantly superior to other self-lubricating materials in terms of reducing the grinding temperature and the thickness of the white layer on the rail after grinding. In summary, after comprehensive consideration, a composite self-lubricating material of graphite and tungsten sulfide is selected. Both polymethyl methacrylate material and carbamide material are pore-forming materials used in grinding wheels and can achieve effective pore formation.

[0017] Preferably, the wetting agent includes phenolic resin solution.

[0018] Preferably, the particle size of the resin binder is 280 - 350 mesh, the particle size of the abrasive is 16 - 24 mesh, the particle size of the self-lubricating pore-forming filler is 16 - 24 mesh, and the particle size of the functional filler is 100 - 150 mesh.

[0019] Based on the defined indicators of the above process, in actual operation, as presented in one or more embodiments of the present invention, the preparation of the polymethyl methacrylate graphite tungsten sulfide composite filler can be carried out according to the following steps or other suitable methods: S1. Weigh each raw material in proportion, and perform ball milling, mixing, and dispersion on polymethyl methacrylate, graphite powder, and tungsten sulfide powder to obtain a mixed component; S2. Add aramid fiber to the above mixed component, continue to perform ball milling, mixing, and dispersion, and obtain a solid component after sufficient mixing; the solid component is dried and placed in a constant temperature and humidity environment; S3. Add the solid component to the epoxy resin solution in batches and stir, add the curing agent after mixing evenly, and fully stir to obtain a mixed material; then perform degassing treatment to obtain a filler component; S4. Heat the filler component to make it cured and formed to obtain a formed component; the formed component is crushed and sieved to obtain polymethyl methacrylate graphite tungsten sulfide composite filler particles.

[0020] In the second aspect of the present invention, there is provided a method for preparing the low-heat and high-efficiency resin-based grinding wheel according to the first aspect of the present invention, comprising the following steps: (1) Weigh each raw material according to a ratio, mix brown fused alumina, zirconium corundum, and cubic boron nitride to obtain a mixed abrasive; add a self-lubricating pore-forming filler to the mixed abrasive to make an abrasive component; mix a resin binder and a functional filler to make an auxiliary component; dry the abrasive component and the auxiliary component and place them in a constant temperature and humidity environment; (2) Add a wetting agent to the abrasive component for mixing, and then add the auxiliary component after completion. After mixing, a mixed component is made; the mixed component is sieved to obtain a loose grinding wheel component, and after sieving, it is left standing in a constant temperature and humidity environment; (3) The grinding wheel component is pressed to make a grinding wheel forming sample; the grinding wheel forming sample is hot press sintered and then hardened to obtain a low-heat and high-efficiency resin-based grinding wheel.

[0021] Based on the above technical solutions, the design concept and principle of the present invention are as follows: The present invention adds a self-lubricating pore-forming filler to traditional grinding wheel materials. The difference between the self-lubricating pore-forming filler and traditional self-lubricating materials is that in traditional grinding wheels, self-lubricating materials are usually directly added to the grinding wheel matrix material to achieve the release of self-lubricating materials during the grinding process. The disadvantage is that directly adding self-lubricating materials to the matrix material will cause a significant decrease in the mechanical strength and material wear resistance of the grinding wheel, significantly reducing the service life and safety performance of the grinding wheel. In existing solutions, fiber fillers are often used as reinforcing agents, and the strength of the resin matrix is improved by "anchoring" the resin matrix with high aspect ratio fiber fillers, but the problems such as easy stacking, difficult dispersion, and easy slippage of sheet structures of solid lubricating materials at high concentrations cannot be solved, and it is difficult for the matrix material to withstand a higher content of solid self-lubricating materials; and the above problems can be effectively solved by the self-lubricating pore-forming filler.

[0022] The characteristics of the self-lubricating pore-forming filler are that it has relatively high hardness and compressive strength at room temperature, can withstand the pressure exerted by the grinding wheel pressing process without breaking, and maintains its original size and morphology. During the hardening process of the grinding wheel by firing, the pore-forming material components in the self-lubricating pore-forming filler decompose when heated at high temperature, releasing the solid lubricant components in the self-lubricating pore-forming filler. The solid lubricating material has relatively high heat resistance and can maintain stable physical properties at the high-temperature hardening temperature of the grinding wheel. For the self-lubricating pore-forming filler, at room temperature, the binder, pore-forming agent components, etc. in the filler wrap the solid self-lubricating material or wrap the solid lubricating material through the molten pore-forming agent material. The wrapped particles have a certain shape and strength, and the filler particles have a relatively high bonding strength with the resin matrix, minimizing the influence of the solid self-lubricating component on the matrix material. At the same time, the filler particles occupy a certain volume of space with a regular shape during the grinding wheel preparation process. During the firing process of the grinding wheel, the pore-forming material components decompose, forming a pore structure in the grinding wheel, and the self-lubricating material components are released into the prepared pores after the decomposition of the pore-forming components; the self-lubricating material is finally stored in the pores of the formed grinding wheel and is not added to the grinding wheel matrix components, avoiding the influence of problems such as easy stacking, difficult dispersion, and easy slippage of the flaky structure of high-content solid lubricants on the performance of the grinding wheel matrix. Therefore, it can accommodate a higher content of solid self-lubricating materials than the prior art.

[0023] In practical applications, the abrasive in the grinding wheel mainly has two functions during the grinding process: cutting and friction. Cutting realizes the peeling of materials, and friction is the main reason for the heat generation during cutting. The pore structure of the low-heat and high-efficiency resin-based grinding wheel can effectively accommodate the grinding debris generated at the grinding wheel / rail contact interface, and under the action of the centrifugal force of the grinding wheel after separating from the contact interface, the high-temperature heat source of the grinding debris is discharged in a timely manner. At the same time, the pores can effectively increase the protrusion height of the abrasive in the grinding wheel and improve the grinding performance of the abrasive. The solid lubricating material of the grinding wheel is released through the pore structure on the grinding wheel / rail contact surface, acting on the surface of the abrasive and the rail, and can realize the lubrication effect of the contact interface between the abrasive and the material, reducing the heat generation due to friction. At the same time, the pores can accommodate the grinding debris as a high-temperature heat source; the solid self-lubricating material is released in the pores after the decomposition of the pore-forming material, avoiding the decline of the mechanical properties and structural stability of the grinding wheel caused by directly adding the self-lubricating material to the grinding wheel matrix material.

[0024] In summary, the self-lubricating pore-forming filler forms pores through the decomposition of the pore-forming components, and the solid self-lubricating material released in the pores can act on the grinding wheel / rail contact surface, reducing the heat generation due to friction during the cutting process; by timely accommodating and discharging the high-temperature heat source and reducing the heat generation at the source in two ways, the function of low heat generation is realized, the protrusion height of the abrasive and the cutting performance are improved, and high-efficiency grinding is achieved.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects: The invention provides a low-heat and high-efficiency resin-based grinding wheel, which has the advantages of high grinding efficiency, low heat generation and good grinding quality, and has good application prospects in railway rail grinding operations.

[0026] The invention provides a preparation method of a low-heat and high-efficiency resin-based grinding wheel, which has the characteristics of simple process and easy operation, and can realize the production of the low-heat and high-efficiency resin-based grinding wheel with high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a comparison diagram of the grinding marks of the low-heat and high-efficiency resin-based grinding wheel prepared in Example 1 and the comparative sample of Comparative Example 1 before and after the on-site grinding operation of the rail; Figure 2 The thickness of the white layer of the rail after grinding of the low-heat and high-efficiency resin-based grinding wheel prepared in Example 1 and the comparative sample of Comparative Example 1; Figure 3 The friction coefficient test results of the low-heat and high-efficiency resin-based grinding wheels prepared in Examples 1 and 2 and the comparative sample of Comparative Example 1 during the grinding process. DETAILED DESCRIPTION

[0028] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0029] Example 1 This embodiment provides a low-heat and high-efficiency resin-based grinding wheel, which is prepared by the following method: (1) Preparation of self-lubricating pore-forming materials: S1. According to the mass percentage, weigh 35 parts of polymethyl methacrylate, 10 parts of graphite powder, and 8 parts of tungsten sulfide, place them in a ball mill for ball milling and mixing dispersion, the ball mill speed is 300 rpm, and the ball-to-material ratio is 1:0.6; the particle size of polymethyl methacrylate is above 60 mesh, and the particle size of graphite powder and tungsten sulfide powder is above 200 mesh; S2. According to the weight percentage, 6 parts of aramid fiber were weighed and added to the above mixed components, and the mixture was placed in a ball mill for ball milling and mixing dispersion. The ball mill speed was 300 rpm, and the ball-to-material ratio was 1:0.6. The diameters were 10-50 μm, and the lengths were 0.8-3 mm. After thorough mixing, a solid component was obtained. The solid component was placed in an oven, dried at 60 °C for 24 h, and placed in a constant temperature and humidity environment. S3. Weigh 30 parts by mass of the epoxy resin liquid, place it in a rotary stirrer, with a rotation speed of 350 rpm, stir for 10 minutes each time, then stop stirring for 5 minutes to cool down. After each cooling, add the solid components and continue stirring. The solid components are added in four times and thoroughly mixed. Finally, add the curing agent and stir for 5 minutes with a rotation speed of 400 rpm. Conduct vacuum treatment on the uniformly mixed composite material to discharge the bubbles generated during stirring, and then obtain the filler component. S4. Transfer the filler component into a muffle furnace, keep it at 60 °C for 2 hours, raise the temperature to 120 °C at a heating rate of 60 °C / h, keep it at 120 °C for 4 hours, and then cool it down to 30 °C with the furnace to obtain the formed component. Crush the formed component mechanically and then screen it, and separate it according to three gradients of 10 - 16 mesh, 16 - 24 mesh, and 24 - 36 mesh; obtain polymethyl methacrylate graphite tungsten sulfide composite filler particles with uniform particle size. (2) Premix: Weigh 35 parts of brown fused alumina, 65 parts of zirconia alumina, and 15 parts of cubic boron nitride by mass of the abrasive and mix them; the brown fused alumina is selected with a mesh number of 24, the zirconia alumina is selected with a mesh number of 16, and the cubic boron nitride is selected with a mesh number of 24. Feed the abrasive into a mixer and mix for 5 minutes to achieve thorough mixing and obtain the mixed abrasive. Weigh 22 parts of the self-lubricating pore-forming filler by mass of the self-lubricating pore-forming filler; the self-lubricating pore-forming filler is selected with a mesh number of 24. Add the self-lubricating pore-forming filler to the above-mentioned mixed abrasive and mix thoroughly for 3 minutes to make the abrasive component. Weigh 15 parts of phenolic resin powder, 3 parts of cryolite, 5.5 parts of pyrite, 2 parts of feldspar powder, and 5 parts of precipitated barium sulfate by mass of the resin binder and functional filler; the phenolic resin powder is selected with a mesh number of 300 and the functional filler has a mesh number of 150. Feed the phenolic resin powder and the functional filler into a drum mixer and mix thoroughly for 5 hours to make the auxiliary component. Drying: Dry the abrasive component and the auxiliary component in an oven at 60 °C for 24 hours and place them in a constant temperature and humidity environment. (3) Mixing: Select phenolic resin liquid as the wetting agent, weigh 3 parts of phenolic resin liquid, add the phenolic resin liquid to the abrasive component and mix thoroughly for 5 minutes; then add the auxiliary component and mix thoroughly for 5 minutes to make the mixed component. Sieving: Sieve the mixed component with a sieve mesh number of 10 to obtain a loose grinding wheel component, and let it stand in a constant temperature and humidity environment after sieving. (4) Pressing: Apply mold release agent around the mold. Place the iron matrix at the bottom of the mold and add the grinding wheel components in three times according to the required proportion of the grinding wheel. After each addition, level the grinding wheel components. After the addition is complete, rotate and level the grinding wheel components. After leveling, cover the upper mold and compact it with a pressure of 10 MPa for 30 s to make a grinding wheel forming sample. Hot pressing and sintering: Hot press and sinter the grinding wheel forming sample at a pressure of 10 MPa and a temperature of 130 °C for 50 min. Hardening: Preheat the muffle furnace to 50 °C. Put the hot press sintered grinding wheel forming sample into the muffle furnace for high-temperature hardening. The high-temperature hardening heating rate curve is as follows: keep the temperature at 50 °C for 2 h, raise the temperature to 100 °C at a heating rate of 50 °C / h, keep the temperature at 100 °C for 1 h, raise the temperature to 130 °C at a heating rate of 30 °C / h, keep the temperature at 130 °C for 2 h, raise the temperature to 185 °C at a heating rate of 27.5 °C / h, keep the temperature at 185 °C for 3 h, and then cool it to 30 °C with the furnace to make a low-heat and high-efficiency resin-based grinding wheel.

[0030] Example 2 This example provides a low-heat and high-efficiency resin-based grinding wheel, which is prepared by the following method: (1) In this example, the self-lubricating pore-forming filler is made by the method of Example 1. (2) Premix: By mass, weigh 35 parts of brown fused alumina, 65 parts of zirconium corundum, and 10 parts of cubic boron nitride for mixing. The brown fused alumina has a mesh number of 24, the zirconium corundum has a mesh number of 16, and the cubic boron nitride has a mesh number of 20. Feed the abrasives into a mixer and mix for 5 min to achieve full mixing and obtain mixed abrasives. By mass, weigh 20 parts of self-lubricating pore-forming filler. The self-lubricating pore-forming filler has a mesh number of 24. Add the self-lubricating pore-forming filler to the above mixed abrasives and mix well for 3 min to make an abrasive component. By mass, weigh 15 parts of phenolic resin powder, 3 parts of cryolite, 5.5 parts of pyrite, 2 parts of feldspar powder, and 5 parts of precipitated barium sulfate for the resin binder and functional fillers. The phenolic resin powder has a mesh number of 300 and the functional fillers have a mesh number of 150. Feed the phenolic resin powder and functional fillers into a drum mixer and mix well for 5 h to make an auxiliary component. Drying: Dry the abrasive component and the auxiliary component in an oven at 60 °C for 24 h and place them in a constant temperature and humidity environment. (3) Mixing: Select phenolic resin solution as the wetting agent, weigh 3 parts of phenolic resin solution, add the phenolic resin solution to the abrasive component, and mix well for 5 min; then add the auxiliary component and mix well for 5 min to make a mixed component; Sieving: Sieve the mixed component with a sieve mesh of 10 meshes to obtain a loose grinding wheel component, and let it stand in a constant temperature and humidity environment after sieving; (4) Pressing: Apply a mold release agent to the four sides of the mold, place an iron matrix at the bottom of the mold, and add the grinding wheel component in 3 times according to the required proportion of the grinding wheel; level the grinding wheel component each time after adding; after adding, rotate and level the grinding wheel component; after leveling, cover the upper mold and compact it with a pressure of 10 MPa and hold the pressure for 30 s; make a grinding wheel forming sample; Hot press sintering: Hot press sinter the grinding wheel forming sample at a pressure of 10 MPa and a temperature of 130 °C for 50 min; Hardening: Preheat the muffle furnace to 50 °C, put the hot press sintered grinding wheel forming sample into the muffle furnace for high-temperature hardening. The high-temperature hardening heating curve is: keep the temperature at 50 °C for 2 h, raise the temperature to 100 °C at a heating rate of 50 °C / h, keep the temperature at 100 °C for 1 h, raise the temperature to 130 °C at a heating rate of 30 °C / h, keep the temperature at 130 °C for 2 h, raise the temperature to 185 °C at a heating rate of 27.5 °C / h, keep the temperature at 185 °C for 3 h, and then cool it to 30 °C with the furnace to make a low-heat and high-efficiency resin-based grinding wheel.

[0031] Example 3 This example provides a low-heat and high-efficiency resin-based grinding wheel, which is prepared by the following method: (1) In this example, the self-lubricating pore-forming filler is made by the method of Example 1; (2) Premix: According to the mass fraction, weigh 35 parts of brown fused alumina, 65 parts of zirconium corundum, and 10 parts of cubic boron nitride for mixing; the brown fused alumina has a mesh number of 24 meshes, the zirconium corundum has a mesh number of 16 meshes, and the cubic boron nitride has a mesh number of 20 meshes; send the abrasive into a mixer and mix for 5 min to achieve full mixing to obtain a mixed abrasive; According to the mass fraction, weigh 18 parts of self-lubricating pore-forming filler; the self-lubricating pore-forming filler has a mesh number of 24 meshes; add the self-lubricating pore-forming filler to the above mixed abrasive and mix well for 3 min to make an abrasive component; For the resin binder and the functional filler, by mass parts, weigh 15 parts of phenolic resin powder, 3 parts of cryolite, 5.5 parts of pyrite, 2 parts of feldspar powder, and 5 parts of precipitated barium sulfate; the phenolic resin powder has a mesh number of 300, and the functional filler has a mesh number of 150; feed the phenolic resin powder and the functional filler into a drum mixer and mix well for 5 h to prepare an auxiliary component. Drying: Dry the abrasive component and the auxiliary component in an oven at 60 °C for 24 h and place them in a constant temperature and humidity environment. (3) Mixing: Select phenolic resin liquid as the wetting agent, weigh 3 parts of phenolic resin liquid, add the phenolic resin liquid to the abrasive component, and mix well for 5 min; then add the auxiliary component and mix well for 5 min to prepare a mixed component. Sieving: Sieve the mixed component with a mesh number of 10 to obtain a loose grinding wheel component, and let it stand in a constant temperature and humidity environment after sieving. (4) Pressing: Apply a release agent to the four sides of the mold, place an iron matrix at the bottom of the mold, and add the grinding wheel component in 3 times according to the required proportion of the grinding wheel; level the grinding wheel component after each addition; after adding, rotate and level the grinding wheel component; after leveling, cover the upper mold and compact it with a pressure of 10 MPa and hold the pressure for 30 s to prepare a grinding wheel forming sample. Hot press sintering: Hot press sinter the grinding wheel forming sample at a pressure of 10 MPa and a temperature of 130 °C for 50 min. Hardening: Preheat the muffle furnace to 50 °C, put the hot press sintered grinding wheel forming sample into the muffle furnace for high-temperature hardening, and the high-temperature hardening heating curve is: keep warm at 50 °C for 2 h, raise the temperature to 100 °C at a heating rate of 50 °C / h, keep warm at 100 °C for 1 h, raise the temperature to 130 °C at a heating rate of 30 °C / h, keep warm at 130 °C for 2 h, raise the temperature to 185 °C at a heating rate of 27.5 °C / h, keep warm at 185 °C for 3 h, and then cool it to 30 °C with the furnace to prepare a low-heat and high-efficiency resin-based grinding wheel.

[0032] Example 4 The preparation method of the resin-based grinding wheel and the self-lubricating pore-forming filler in this example is the same as that in Example 1, except for the different formula ratios of the resin-based grinding wheel.

[0033] The pore-forming filler for resin-based grinding wheels in this embodiment includes: by weight, 35 parts of brown fused alumina, 60 parts of zirconium corundum, 15 parts of cubic boron nitride, 15 parts of phenolic resin powder, 3 parts of cryolite, 5 parts of pyrite, 2 parts of feldspar powder, 5 parts of precipitated barium sulfate, 3 parts of phenolic resin liquid, and 18 parts of self-lubricating pore-forming filler.

[0034] Example 5 The preparation method of the resin-based grinding wheel and the self-lubricating pore-forming filler in this embodiment is the same as that in Example 1, except for the different formula ratios used in the resin-based grinding wheel.

[0035] The pore-forming filler for resin-based grinding wheels in this embodiment includes: by weight, 40 parts of brown fused alumina, 80 parts of zirconium corundum, 20 parts of cubic boron nitride, 25 parts of phenolic resin powder, 5 parts of cryolite, 7 parts of pyrite, 3 parts of feldspar powder, 10 parts of precipitated barium sulfate, 5 parts of phenolic resin liquid, and 25 parts of self-lubricating pore-forming filler.

[0036] Comparative Example 1 To test the low-temperature and high-efficiency grinding effect of the low-heat and high-efficiency rail grinding wheel for railway rails, this comparative example is set up. The specific preparation method of the comparative sample is as follows: (1) Premix: For the abrasive, weigh 35 parts of brown fused alumina, 75 parts of zirconium corundum, and 10 parts of cubic boron nitride by mass and mix them; the brown fused alumina is selected with a mesh number of 24, the zirconium corundum is selected with a mesh number of 16, and the cubic boron nitride is selected with a mesh number of 20; send the abrasive into a mixer and mix for 5 min to achieve full mixing, obtaining a mixed abrasive. For the resin binder and functional fillers, weigh 15 parts of phenolic resin powder, 3 parts of cryolite, 5.5 parts of pyrite, 2 parts of feldspar powder, and 10 parts of precipitated barium sulfate by mass; the phenolic resin powder is selected with a mesh number of 300 and the functional fillers have a mesh number of 150; send the phenolic resin powder and functional fillers into a drum mixer and mix them fully for 5 h to make an auxiliary component. Drying: Dry the abrasive component and the auxiliary component in an oven at 60 °C for 24 h and place them in a constant temperature and humidity environment. (2) Mixing: Select phenolic resin liquid as the wetting agent, weigh 3 parts of phenolic resin liquid, add the phenolic resin liquid to the abrasive component and mix well for 5 min; then add the auxiliary component and mix well for 5 min to make a mixed component. Sieving: Sieve the mixed component with a sieve mesh number of 10 to obtain a loose grinding wheel component, and let it stand in a constant temperature and humidity environment after sieving. (3) Pressing: Apply mold release agent around the mold. Place the iron matrix at the bottom of the mold and add the grinding wheel components in 3 times according to the required proportion of the grinding wheel. After each addition, level the grinding wheel components; after the addition is complete, rotate and level the grinding wheel components; after leveling, cover the upper mold and compact it with a pressure of 10 MPa for 30 s to make a grinding wheel forming sample. Hot pressing and sintering: Hot press and sinter the grinding wheel forming sample at a pressure of 10 MPa and a temperature of 130 °C for 50 min. Hardening: Preheat the muffle furnace to 50 °C, put the hot-pressed and sintered grinding wheel forming sample into the muffle furnace for high-temperature hardening. The high-temperature hardening heating rate curve is as follows: keep the temperature at 50 °C for 2 h, raise the temperature to 100 °C at a heating rate of 50 °C / h, keep the temperature at 100 °C for 1 h, raise the temperature to 130 °C at a heating rate of 30 °C / h, keep the temperature at 130 °C for 2 h, raise the temperature to 185 °C at a heating rate of 27.5 °C / h, keep the temperature at 185 °C for 3 h, and then cool it in the furnace to 30 °C to make the finished grinding wheel.

[0037] Use a small rail grinding machine to test the grinding performance of the low-heat and high-efficiency resin-based grinding wheel for railway rail grinding prepared in Example 1 and the comparison sample of Comparative Example 1. The grinding piece is a 60 rail, and the material of the 60 rail is U71Mn rail steel. The test results are as Figure 1 shown.

[0038] From Figure 1 the comparison, it can be seen that after the grinding wheel prepared in Example 1 completes a single grinding, the grinding edge is clear and straight, the grinding marks on the grinding surface are evenly distributed, and the surface is smooth and free of obvious burns after grinding; while after the grinding wheel prepared in Comparative Example 1 completes a single grinding, there is a certain arc at the edge, the grinding marks are of different depths, and the surface shows surface burns after grinding.

[0039] Use a rail grinding testing machine to conduct a rail sample grinding test on the grinding wheel samples prepared in Example 1 and Comparative Example 1. The grinding parameters refer to the parameters selected on-site. The grinding pressure is 700 N, and the grinding time is 30 s. Collect characterization parameters such as grinding pressure, friction torque, and grinding speed through the sensors of the testing machine, and judge the rail grinding quality through the cross-sectional morphology of the rail sample. The test results are as Figure 2 .

[0040] From Figure 2It can be seen that the thickness of the white layer polished in Example 1 is significantly lower than that in Comparative Example 1, and the thickness distribution of the white layer is uniform; during the grinding process under the thermo-mechanical coupling condition, the metallographic transformation is likely to occur on the polished surface of the rail, generating a hard and brittle white layer, and the thickness of the white layer will increase significantly at high temperatures. The white layer is prone to spalling under the cyclic contact fatigue of the rail, resulting in surface defects of the rail, which affect the service life and safety of the rail; thus, it can be seen that Example 1 can effectively reduce the thickness of the white layer caused by grinding heat on the rail surface, improve the pre-fatigue caused by grinding of the rail, and further improve the surface quality of the polished rail and extend the service cycle of the rail.

[0041] The friction coefficients of the grinding wheel specimens prepared in Example 1, Example 2 and Comparative Example 1 during the grinding process were tested, and the results are as Figure 3 shown.

[0042] It can be Figure 3 seen that the friction coefficients of the grinding wheels prepared in Example 1 and Example 2 are both significantly reduced, and the decline range of the friction coefficient is larger after the content of the self-lubricating pore-forming filler increases; the lower friction coefficient indicates that the friction behavior during the grinding process is alleviated, and the heat generation during grinding decreases accordingly.

[0043] The above results show that the present invention adopts a self-lubricating pore-forming filler in the grinding wheel composition. Through the decomposition of its pore-forming component, pores are formed, and the protrusion height of the abrasive grains is increased by using the pores, improving the cutting performance and realizing the function of high-efficiency grinding. In actual operation, the pores can accommodate the grinding chips as high-temperature heat sources; the solid self-lubricating material is released in the pores after the decomposition of the pore-forming material, avoiding the decline of the mechanical properties and structural stability of the grinding wheel caused by directly adding the self-lubricating material to the grinding wheel matrix material. The solid self-lubricating material released in the pores can act on the contact surface between the grinding wheel and the rail, reducing the friction heat generation during the cutting process; by timely accommodating and removing the high-temperature heat source (grinding chips) and reducing the heat generation at the source (friction heat generation) in two ways, the function of low heat generation is realized.

[0044] In summary, the low-heat and high-efficiency resin-based grinding wheel for railway rail grinding provided by the present invention has good grinding performance and grinding accuracy. The surface quality of the rail after grinding is good, and the rail burning situation is significantly reduced. It can realize low-heat-generation and high-precision rail grinding and can meet the rail grinding and repair work of rail transit.

[0045] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A low-heat and high-efficiency resin-based grinding wheel, characterized in that: The raw materials include, by weight: 110-140 parts of abrasive, 15-25 parts of resin adhesive, 15-25 parts of functional filler, 18-25 parts of self-lubricating pore-forming filler, and 3-5 parts of wetting agent.

2. The low-heat and high-efficiency resin-based grinding wheel according to claim 1, characterized in that: The abrasive comprises 35-40 parts of brown corundum, 60-80 parts of zirconium corundum and 15-20 parts of cubic boron nitride.

3. The low-heat and high-efficiency resin-based grinding wheel according to claim 1, characterized in that: The resin adhesive includes phenolic resin powder.

4. The low-heat and high-efficiency resin-based grinding wheel according to claim 1, characterized in that: The functional filler comprises 5-10 parts of precipitated barium sulfate, 3-5 parts of cryolite, 5-7 parts of pyrite powder and 2-3 parts of feldspar powder.

5. The low-heat and high-efficiency resin-based grinding wheel according to claim 1, characterized in that: The self-lubricating pore-forming filler is a polymethyl methacrylate graphite tungsten sulfide composite filler; its components include a pore-forming component, a self-lubricating component, an adhesive, and aramid fiber; wherein the pore-forming component is polymethyl methacrylate, the self-lubricating component is flaky graphite powder and tungsten sulfide powder, the adhesive is epoxy resin, and the reinforcing component is aramid fiber.

6. The low-heat, high-efficiency resin-based grinding wheel according to claim 5, characterized in that: The preparation method of the polymethyl methacrylate graphite tungsten sulfide composite filler comprises the following steps: Epoxy resin liquid is used as an adhesive to wrap polymethyl methacrylate as a pore-forming component and graphite powder and tungsten sulfide powder as self-lubricating components. Aramid fiber is added to improve the adhesion of epoxy resin to polymethyl methacrylate, graphite and tungsten sulfide. After curing and molding, the composite filler of polymethyl methacrylate, graphite and tungsten sulfide is obtained by crushing and sieving.

7. The low-heat, high-efficiency resin-based grinding wheel according to claim 5, characterized in that: In the polymethyl methacrylate graphite tungsten sulfide composite filler, the proportions of the components are 30-40 parts of epoxy resin, 4-8 parts of aramid fiber, 30-40 parts of polymethyl methacrylate, 6-12 parts of graphite powder, and 4-8 parts of tungsten sulfide, calculated by mass.

8. The low-heat and high-efficiency resin-based grinding wheel according to claim 1, characterized in that: The wetting agent includes a phenolic resin solution.

9. The low-heat and high-efficiency resin-based grinding wheel according to claim 1, characterized in that: The particle size of the resin adhesive is 280-350 meshes, the particle size of the abrasive is 16-24 meshes, the particle size of the self-lubricating pore-forming filler is 16-24 meshes, and the particle size of the functional filler is 100-150 meshes.

10. A method for preparing a low-heat, high-efficiency resin-based grinding wheel according to any one of claims 1 to 9, characterized in that: The steps include: (1) Weighing the raw materials in proportion, mixing brown corundum, zirconium corundum and cubic boron nitride to obtain a mixed abrasive; adding a self-lubricating pore-forming filler to the mixed abrasive to prepare an abrasive component; mixing a resin adhesive with a functional filler to prepare an auxiliary material component; drying the abrasive component and the auxiliary material component and placing them in a constant temperature and humidity environment; (2) adding a wetting agent to the abrasive component and mixing them, and then adding the auxiliary material component and mixing them to form a mixed component; the mixed component is sieved to obtain a loose grinding wheel component, and after sieving, it is left to stand in a constant temperature and humidity environment; (3) The grinding wheel components are pressed to form a grinding wheel molded sample; the grinding wheel molded sample is hot-pressed and sintered, and then hardened to obtain a low-heat and high-efficiency resin-based grinding wheel.

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