High-strength low-burn resin-based self-lubricating grinding wheel and preparation method thereof

Abstract

The application discloses a resin-based self-lubricating grinding wheel with high strength and low burn and a preparation method thereof. The grinding wheel comprises a resin binder, a wetting agent, functional fillers, reinforcing fibers, self-lubricating powder, self-lubricating composite fillers and abrasive materials. First, the raw materials are dried, and the functional fillers, the reinforcing fibers, the self-lubricating powder and the abrasive materials are subjected to surface modification treatment, and then the raw materials are mixed. The self-lubricating composite fillers are a pre-prepared composite material comprising a resin binder, reinforcing fillers, lubricants and fiber materials. The mixed raw materials are subjected to pre-pressing, curing and forming to obtain the resin-based self-lubricating grinding wheel with high strength and low burn. The resin-based self-lubricating grinding wheel prepared by the application has high mechanical properties, and the self-lubricating components can be released at the grinding wheel / workpiece interface during the working of the grinding wheel, thereby playing a lubricating and friction-reducing role, so that the grinding temperature is reduced, the surface quality of the workpiece is improved and the service life of the grinding wheel is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of manufacturing grinding wheel for grinding process, and relates to a resin bond grinding wheel preparation technology, in particular to a high-strength low-burn resin bond self-lubricating grinding wheel and a preparation method thereof. BACKGROUND

[0002] Grinding process is one of the main processing methods for removing the surface material of workpiece by high-speed rotating grinding wheel. Resin bond is widely used in the molding manufacturing of grinding wheel due to its low cost, convenient molding, good toughness, impact resistance and other characteristics. Usually, the abrasive in the grinding wheel is cut with a large negative rake angle, and a large amount of grinding heat is generated during the grinding process, especially under extreme grinding conditions such as high load, high linear speed, large feed amount and continuous grinding. The weakness of resin bond is poor heat resistance. The performance of resin declines sharply at high temperature, thereby reducing the holding force of abrasive and accelerating the wear of grinding wheel, thus shortening the service life of grinding wheel. At the same time, under the action of high grinding temperature, it is inevitable to cause thermal damage to the surface of workpiece, such as thermal cracks, burns, surface hard and brittle layer (such as white layer), oxidation, etc., which directly affects the service performance (fatigue strength, wear resistance, corrosion resistance, dimensional stability, etc.) of the workpiece after grinding. Therefore, reducing the grinding heat and then reducing the grinding temperature is an important means to prolong the service life of resin bond grinding wheel and improve the surface quality of grinding workpiece.

[0003] Coolant and grinding fluid are sprayed to the wheel / workpiece interface in real time through nozzles, which can effectively reduce grinding heat and improve the surface quality of the workpiece. However, the grinding fluid usually contains mineral oil, surfactant, and corrosion and bactericidal additives, which are harmful to the human body and difficult to recycle, and can easily pollute the environment. Therefore, dry grinding processing technology is called a green processing technology because it does not use or uses less grinding fluid, which has less negative impact on the environment. In the dry grinding state, in order to reduce the generation of heat during grinding, the friction coefficient of the wheel / workpiece interface is usually improved by adding solid lubricant to the grinding wheel. Solid lubricant powders such as graphite, molybdenum disulfide, and fluorite are usually added to the grinding wheel formula in the form of fillers (such as CN 108972390 B; INT J MACH TOOL MANU, 2012, 56:94-101), so that the solid lubricant is uniformly dispersed in the resin bond, and then the solid lubricant can be released in the grinding process with the wear of the resin bond, thereby playing a lubricating role. However, most solid lubricants have low surface energy and are difficult to be infiltrated by resin; at the same time, their unique lamellar structure is prone to slip between the lamellae, thereby significantly reducing the mechanical properties of the bond. Although excessive addition of self-lubricating powder can improve the lubrication effect, it significantly reduces the mechanical strength and grinding capacity of the grinding wheel (Int J Adv Manuf Tech 2016; 85(9-12):2235-2245). If the content of the solid lubricant is too low, it cannot guarantee good lubrication effect. Therefore, there is a contradiction between the lubrication performance and the mechanical properties and grinding performance of the grinding wheel in improving the grinding heat of the wheel / workpiece surface by adding solid lubricant. In summary, it has important scientific significance and engineering value to improve the allowable addition amount of self-lubricating fillers in the grinding wheel on the basis of maintaining the mechanical properties of the resin bond grinding wheel, thereby reducing the grinding heat in the dry grinding state, prolonging the service life of the grinding wheel, and improving the surface quality of the workpiece. SUMMARY

[0004] The purpose of the present application is to solve the above-mentioned problems in the prior art, and to provide a resin-based self-lubricating grinding wheel with high strength and low burn and a preparation method thereof. The self-lubricating function of the resin-based grinding wheel is used to reduce the grinding heat during the grinding process of the resin-based grinding wheel, prolong the service life of the grinding wheel, improve the surface quality of the ground workpiece, and thus realize green and high-precision grinding processing.

[0005] The technical solution of the present application to solve the above technical problems is as follows:

[0006] A resin-based self-lubricating grinding wheel with high strength and low burn is obtained by mixing, pre-pressing and curing the grinding wheel raw material, wherein the grinding wheel raw material comprises: 12-20 parts by weight of resin binder, 6-8 parts by weight of wetting agent, 6-12 parts by weight of functional filler, 3-8 parts by weight of reinforcing fiber, 1-3 parts by weight of self-lubricating powder, 12-18 parts by weight of self-lubricating composite filler, and 65-85 parts by weight of abrasive.

[0007] Further preferably, the grinding wheel raw material comprises: 13-18 parts by weight of resin binder, 6-8 parts by weight of wetting agent, 6-10 parts by weight of functional filler, 3-6 parts by weight of reinforcing fiber, 1-2 parts by weight of self-lubricating powder, 12-15 parts by weight of self-lubricating composite filler, and 70-85 parts by weight of abrasive.

[0008] Still further preferably, the grinding wheel raw material of the resin-based self-lubricating grinding wheel with high strength and low burn is optimized as follows: 15 parts by weight of resin binder, 7 parts by weight of wetting agent, 8 parts by weight of functional filler, 6 parts by weight of reinforcing fiber, 2 parts by weight of self-lubricating powder, 15 parts by weight of self-lubricating composite filler, and 80 parts by weight of abrasive.

[0009] Further, the resin binder is one of modified phenolic resin powder, polyimide resin powder and bismaleimide resin powder. The main function of the resin binder is to bond the functional filler, reinforcing fiber, abrasive and self-lubricating particles, and to endow the grinding wheel with certain mechanical properties.

[0010] Further preferably, the particle size of the modified phenolic resin powder, polyimide resin powder and bismaleimide resin powder is more than 100 mesh. Most preferably, the resin binder is modified phenolic resin powder.

[0011] Further, the wetting agent is one of epoxy resin liquid and phenolic resin liquid. The main function of the wetting agent is to infiltrate the abrasive, and to bond the resin binder, functional filler, reinforcing fiber, abrasive and self-lubricating powder on the surface of the abrasive during the mixing stage, while ensuring that the molding material has good molding performance during the pressing process.

[0012] Most preferably, the wetting agent is phenolic resin liquid.

[0013] Further preferably, the viscosity of the wetting agent is 570-650 mPa·s at 25°C, and the density is 1.15-1.30 g / cm 3 .

[0014] Further, the functional filler is a reinforcing filler selected from any one or combination of hemihydrate gypsum powder, ice crystal stone powder, pyrite powder, quartz powder, corundum powder, iron oxide powder and zirconium tetrafluoride powder. The functional filler can improve the density, strength and grinding performance of the resin-based grinding wheel.

[0015] Further preferably, the pyrite powder, quartz powder, corundum powder in the functional filler has a particle size of 60 mesh or more, and the hemihydrate gypsum powder, cryolite powder, iron oxide powder, zirconium tetrafluoride powder in the functional filler has a particle size of 100 mesh or more.

[0016] Most preferably, the functional filler is a combination of hemihydrate gypsum powder, cryolite powder, corundum powder, iron oxide powder, and zirconium tetrafluoride powder.

[0017] Further, the reinforcing fiber is one or a combination of aramid fiber, carbon fiber, basalt fiber, glass fiber, potassium titanate whisker, steel fiber, and copper fiber. The reinforcing fiber can improve the overall mechanical properties of the resin-based grinding wheel.

[0018] Most preferably, the reinforcing fiber is one or a combination of aramid fiber, basalt fiber, glass fiber, steel fiber, and copper fiber.

[0019] Further preferably, the aramid fiber, carbon fiber, basalt fiber, glass fiber, potassium titanate whisker, steel fiber, and copper fiber in the reinforcing fiber have a diameter of 30-100 μm and a length of 1.0-5.0 mm.

[0020] Further, the self-lubricating powder is one or a combination of graphite powder, molybdenum disulfide powder, tungsten sulfide powder, hexagonal boron nitride powder, and fluorite powder. The self-lubricating powder is uniformly distributed in the resin binder, which can control the toughness of the resin binder and also lubricate the grinding wheel / workpiece interface to some extent, thereby reducing the friction coefficient of the grinding wheel / workpiece interface and the generation of grinding heat, and further improving the grinding burn problem of the workpiece surface.

[0021] Further preferably, the self-lubricating powder in the self-lubricating powder has a particle size of 100 mesh or more.

[0022] Most preferably, the self-lubricating powder in the self-lubricating filler is one or a combination of graphite powder, molybdenum disulfide powder, and tungsten sulfide powder.

[0023] Further, the abrasive is one or a combination of zircon corundum, brown corundum, white corundum, chromium corundum, praseodymium-neodymium corundum, black corundum, diamond, and cubic boron nitride. The main function of the abrasive is to act as a cutting edge during grinding to remove the material on the surface of the workpiece.

[0024] Further preferably, the abrasive material is composed of three kinds of abrasive grains with coarse, medium and fine particle sizes. The average particle sizes of the three kinds of abrasive grains are 1.0d, 0.6-0.8d and 0.2-0.4d, respectively. The three kinds of abrasive grains are in a weight ratio of 10-15:40-55:12-25.

[0025] Most preferably, the average particle sizes of the coarse, medium and fine abrasive grains are 1.0d, 0.6d and 0.2d, respectively. The three kinds of abrasive grains are in a weight ratio of 15:60:25.

[0026] Most preferably, the abrasive material is a combination of one or more of zirconia alumina, brown alumina, chromium alumina, praseodymium-neodymium alumina and cubic boron nitride.

[0027] Further, the self-lubricating composite filler is a composite particle with uniform particle size, which is prepared by mixing, molding, curing, mechanical crushing, surface plating and sieving of raw materials such as resin binder, reinforcing filler, lubricant and fiber material. The resin binder includes liquid resin binder (such as epoxy resin liquid) and powder resin binder (such as phenolic resin powder, polyimide resin powder and polyether ether ketone powder). The lubricant in the self-lubricating composite filler is a combination of one or more of graphite powder, molybdenum disulfide powder, tungsten sulfide powder and hexagonal boron nitride powder. A large number of overhanging fibers exist on the surface of the self-lubricating composite filler, which can form anchoring with the resin bond of the grinding wheel to improve the mechanical properties of the grinding wheel. The self-lubricating composite filler is uniformly distributed in the resin-based grinding wheel and is released in real time on the surface of the grinding wheel / workpiece contact area during the grinding process, effectively reducing the friction coefficient of the grinding wheel and workpiece interface, thereby reducing the grinding heat and improving the grinding burn of the workpiece surface.

[0028] Most preferably, the lubricant in the self-lubricating composite filler is a combination of one or more of graphite powder, molybdenum disulfide powder and tungsten sulfide powder. The surface of the self-lubricating composite filler is plated with low-temperature chemical copper or nickel.

[0029] Further preferably, the average particle size of the self-lubricating composite filler is 0.2-0.5 times the average particle size of the coarse abrasive grain.

[0030] Further, in the preferred embodiment of the present application, the average particle size of the self-lubricating composite filler is 0.35 times the average particle size of the coarse abrasive grain.

[0031] The present application also provides a preparation method of the self-lubricating composite filler, which comprises the following steps:

[0032] (1) Pretreatment of raw materials

[0033] (11) The reinforcing filler, lubricant, and fiber are respectively subjected to drying treatment by baking;

[0034] (12) The dried reinforcing filler, lubricant, and fiber are respectively subjected to modification treatment by silane coupling agent;

[0035] (13) The modified reinforcing filler, lubricant, and fiber are reserved after ball milling;

[0036] (2) Mixing

[0037] The resin binder is mixed with the reinforcing filler, lubricant, and fiber;

[0038] For liquid resin binder, the reinforcing filler, lubricant, and fiber are added and stirred to obtain a mixture to be cured;

[0039] For powder resin binder, the reinforcing filler, lubricant, and fiber are mixed and ball milled to obtain a mixture to be cured;

[0040] (3) Molding

[0041] The mixture to be cured is subjected to curing molding under curing conditions to obtain a block-shaped self-lubricating composite filler;

[0042] (4) Composite filler shaping

[0043] The block-shaped self-lubricating composite filler is mechanically crushed and sieved to obtain self-lubricating composite filler particles with uniform particle size;

[0044] (5) Surface treatment

[0045] The self-lubricating composite filler particles are subjected to surface coupling modification treatment and / or surface metal layer plating treatment to obtain a self-lubricating composite filler.

[0046] The application also protects a resin-based self-lubricating grinding wheel with high strength and low burn, and a preparation method thereof, comprising the following steps:

[0047] (1) Raw material pretreatment

[0048] (11) The functional filler, reinforcing fiber, self-lubricating powder, and abrasive are respectively subjected to modification treatment by silane coupling agent;

[0049] (12) The resin binder, self-lubricating composite filler, and modified functional filler, reinforcing fiber, self-lubricating powder, and abrasive are subjected to drying treatment;

[0050] (13) The modified and dried functional filler, reinforcing fiber, and self-lubricating powder are reserved after ball milling;

[0051] (2) Mixing

[0052] The functional filler, the reinforcing fiber, the self-lubricating powder and the abrasive infiltrated by the wetting agent are mixed uniformly first, and then mixed with the self-lubricating composite filler, and finally the resin grinding wheel forming material is obtained after screening.

[0053] (3) Pre-pressing

[0054] The resin grinding wheel forming material is put into a mold and pre-pressed under a pressing process to obtain a grinding wheel blank;

[0055] (4) Curing

[0056] The grinding wheel blank is cured under a curing process to obtain a resin-based self-lubricating grinding wheel.

[0057] Preferably, in step (11), the modification method is that the functional filler, the reinforcing fiber, the self-lubricating powder and the abrasive are respectively placed in a 2-3wt% KH560 alcohol solution, and treated for 0.5-1.0h under ultrasonic oscillation, and the ultrasonic process is fully stirred.

[0058] Preferably, in step (12), the drying is carried out in a forced air drying oven, wherein the drying conditions of the resin adhesive and the self-lubricating composite filler are that the baking is carried out at 40-50°C for 40-60h; and the drying conditions of the modified functional filler, the reinforcing fiber, the self-lubricating powder and the abrasive are that the drying and baking are carried out at 70-80°C for 15-20h.

[0059] Preferably, in step (13), the functional filler, the reinforcing fiber and the self-lubricating powder are mixed by using a planetary ball mill, and the ball milling conditions are that the rotation speed of the ball mill is 300-400rpm, and the ball-to-material ratio is 1:0.4.

[0060] Preferably, in step (2), the mixing process is as follows:

[0061] (21) The abrasive weighed according to the proportion is placed in the upper pot of a double-pot countercurrent mixer, the upper pot rotates clockwise at a speed of 60rpm, the fork rotates counterclockwise at a speed of 20rpm, and the stirring is carried out for 3-5min to fully mix and uniformly the abrasives of different particle sizes to obtain mixed abrasives;

[0062] (22) The wetting agent weighed according to the weight ratio is added to the mixed abrasives in (21), and the stirring is continued for 5-8min to obtain the wetted abrasives;

[0063] (23) The functional filler, the reinforcing fiber and the self-lubricating powder mixed by the ball milling in (13) are weighed and added to the upper pot of the double-pot countercurrent mixer, and the stirring is continued for 6-8min to make the functional filler, the reinforcing fiber and the self-lubricating powder uniformly adhere to the surface of the abrasives wetted by the wetting agent. After the stirring is completed, the mixed material is transferred to the lower pot of the double-pot countercurrent mixer;

[0064] (24) Add the powdered resin binder to the lower pot of the double-pot counter-current mixer, rotate the lower pot clockwise at 60 rpm, rotate the fork counterclockwise at 20 rpm, and stir for 1-1.5 min to uniformly coat the abrasive surface with a layer of resin powder;

[0065] (25) Add the weighed self-lubricating composite filler to the lower pot of the double-pot counter-current mixer, continue stirring for 0.5-1.0 min to uniformly disperse the self-lubricating composite filler in the abrasive, and obtain the molding material;

[0066] (26) Screen the molding material in (25), first pass through a fine mesh screen to obtain the screen overs; continue to pass the screen overs through a coarse mesh screen, and the screen unders are the resin grinding wheel molding material;

[0067] Preferably, the fine mesh screen in (26) is two particle size numbers smaller than the fine abrasive in the mixed abrasive; and the coarse mesh screen has a mesh size that is 2 particle size numbers larger than the coarse abrasive;

[0068] Preferably, in step (3), the resin-based grinding wheel pre-pressing molding process is as follows:

[0069] (31) Weigh the molding material in (26) and place it in a mold, and press under the conditions of 50-60°C and 5-10 MPa for 2-5 min;

[0070] (32) Press under the conditions of 120-130°C and 8-10 MPa for 10-15 min;

[0071] (33) Press under the conditions of 170-180°C and 10-15 MPa for 20-25 min; and obtain the grinding wheel blank after natural cooling.

[0072] Preferably, in the pressing stage of (31), the air is released 2-3 times; in the pressing stage of (32), the air is released 5-7 times; and in the pressing stage of (33), the air is released 8-12 times.

[0073] Preferably, in step (4), the curing process of the resin-based grinding wheel blank is divided into a low-temperature stage, a medium-temperature stage, a high-temperature stage, and a cooling stage, and the specific process is as follows:

[0074] (41) Low-temperature stage: bake at 50-60°C for 1-1.5 h to preheat the grinding wheel and dry the moisture;

[0075] (42) Medium-temperature stage: bake at 120-130°C for 2-3 h to adjust the resin flowability;

[0076] (43) High-temperature stage: bake at 175-190°C for 20-28 h to adjust the toughness of the grinding wheel;

[0077] (44) Cooling stage: after the end of (43), the grinding wheel is cooled with the furnace, the stress in the grinding wheel is regulated, and a high-strength low-burn resin-based self-lubricating grinding wheel is obtained after cooling.

[0078] Compared with the prior art, the present application has the following beneficial effects:

[0079] (1) The self-lubricating composite filler surface adopted in the present application has a large number of protruding fibers, which can form anchoring points with the resin binder and improve the bonding strength with the resin binder. At the same time, the surface of the self-lubricating particles is treated with a plating layer, which improves the surface energy of the self-lubricating particles and makes them easy to be infiltrated by the resin. Therefore, by adding the lubricating phase in the form of self-lubricating composite filler to the resin-based grinding wheel, the mechanical properties of the grinding wheel can be ensured on the premise of improving the self-lubricating performance of the grinding wheel.

[0080] (2) By adding the lubricating components in the form of lubricating powder and self-lubricating composite filler to the resin-based grinding wheel, the amount of lubricating components can be increased on the basis of ensuring the high mechanical properties of the grinding wheel. The lubricating components can be released in real time in the grinding wheel / workpiece contact area during the grinding process, thereby lubricating the contact area, greatly reducing the grinding heat and the grinding temperature, and thus improving the thermal degradation problem of the resin-based grinding wheel caused by high temperature, prolonging the service life of the grinding wheel, and improving the surface processing quality of the workpiece.

[0081] (3) The high-strength low-burn resin-based self-lubricating grinding wheel prepared by the present application has high strength, good lubricating performance, long service life, and good surface quality of the workpiece after grinding, and can realize the replacement of contaminated, harmful and difficult-to-recycle grinding fluid / cooling fluid, while reducing the cost of grinding processing and realizing high-precision, high-reliability, high-economy and green grinding processing.

[0082] In summary, the high-strength low-burn resin-based self-lubricating grinding wheel prepared by the present application has high mechanical properties, and the self-lubricating powder and self-lubricating composite particles added in the grinding wheel can be released in situ in the grinding wheel / workpiece contact area during the grinding process, thereby playing a lubricating and friction-reducing role, reducing the grinding heat, improving the thermal degradation problem of the resin-based binder caused by high temperature, improving the wear resistance of the grinding wheel, and reducing the thermal damage defects of the workpiece surface during grinding processing and improving the surface quality of the grinding processing. BRIEF DESCRIPTION OF DRAWINGS

[0083] Figure 1 is a schematic diagram of the preparation process of the high-strength low-burn resin-based self-lubricating grinding wheel of the present application. Figure 1 Figure 1 is a schematic diagram of the preparation process of the high-strength low-burn resin-based self-lubricating grinding wheel of the present application.

[0084] Figure 2 is a schematic diagram of the preparation process of the high-strength low-burn resin-based self-lubricating grinding wheel of the present application. Figure 2 Figure 3 is a curve of the friction coefficient of the grinding wheel / steel rail interface during the grinding process of the resin-based grinding wheels prepared in Examples 2-4 and Comparative Examples 5-6 of the present application.

[0085] Figure 2 is a micrograph of the cross-section of a rail sample prepared according to the method of Example 2 of the present application. Figure 3 Figure 3 is a micrograph of the cross-section of a rail sample prepared according to the method of Example 2 of the present application.

[0086] Figure 4 is a micrograph of the cross-section of a rail sample prepared according to the method of Example 2 of the present application. Figure 4 Figure 5 is an electron backscatter diffraction pattern of a rail sample prepared according to the method of Example 2 of the present application. DETAILED DESCRIPTION

[0087] The principles and features of the present application are described below in conjunction with examples to facilitate understanding of the present application by those skilled in the art. However, it should be clear that the present application is not limited in scope to the specific embodiments, and that any variations that are obvious to those skilled in the art, within the spirit and scope of the present application as defined by the claims appended hereto, are intended to be embraced by the present application. In the examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified, and are all conventional products that can be purchased on the market.

[0088] Example 1

[0089] The method for preparing the self-lubricating composite filler is as follows:

[0090] S(1) Pretreatment of raw materials

[0091] S(11) The precipitated barium sulfate, cryolite, quartz powder, corundum powder, graphite powder, and carbon fiber are placed in a blast drying oven, and dried at 50°C for 30h.

[0092] S(12) The precipitated barium sulfate, cryolite, quartz powder, corundum powder, graphite powder, and carbon fiber are placed in a 3wt% silane coupling agent alcohol solution, and treated under ultrasonic conditions for 1.5h, with constant stirring.

[0093] S(13) The precipitated barium sulfate, cryolite, quartz powder, corundum powder, graphite powder, and carbon fiber after ultrasonic treatment are dried at 50°C for 45h.

[0094] S(14) The precipitated barium sulfate, cryolite, quartz powder, corundum powder, graphite powder, and carbon fiber obtained in step S(13) above are placed in a ball mill for ball milling and dispersion, with a ball mill speed of 300rpm and a ball-to-material ratio of 1:0.6.

[0095] S(2) Mixing

[0096] S(21) The precipitated barium sulfate, cryolite, quartz powder, and corundum powder are mixed and dispersed in a ball mill to obtain a mixed reinforcing filler.

[0097] S(22) Take the epoxy resin liquid heated in the 50°C oven for 10h, dilute the epoxy resin liquid with anhydrous ethanol as diluent under stirring condition, the weight of anhydrous ethanol is 20wt% of the epoxy resin liquid; the stirring paddle speed is 500rpm, and the stirring time is 3min.

[0098] S(23) Add graphite powder into the diluted epoxy resin in 3 times, and stir at 2000rpm for 20min using a stirring paddle.

[0099] S(24) Take the carbon fiber and add it into the epoxy resin liquid in S(23) above, and stir at 2000rpm for 10min.

[0100] S(25) Take the epoxy resin curing agent, the weight ratio of curing agent to epoxy resin is 1:1; dilute the curing agent with anhydrous ethanol as diluent, the weight of anhydrous ethanol is 20wt% of the curing agent; stir using a stirring paddle during the dilution process, the stirring paddle speed is 500rpm, and the stirring time is 3min.

[0101] S(26) Add the diluted curing agent in S(25) above into the epoxy resin liquid in S(24), and keep the stirring speed at 2000rpm;

[0102] S(27) Take the reinforcing filler mixed by the ball mill in S(21) above, and add it into the resin liquid in S(26) above in 3 times, and stir for 10min at 2000rpm, to obtain the epoxy resin molding material;

[0103] S(3) Molding

[0104] S(31) Inject the epoxy resin liquid molding material obtained in S(27) above into a molding mold, and place it in an oven for heating;

[0105] S(32) Further, the epoxy resin liquid molding curing temperature in S(31) above is 60°C, and the curing time is 50h, to obtain a block-shaped self-lubricating composite filler;

[0106] S(4) Self-lubricating composite filler shaping

[0107] S(41) Mechanically crush the block-shaped self-lubricating composite filler after molding in S(3) above, to obtain a granular self-lubricating composite filler;

[0108] S(42) According to the requirements of the grinding wheel molding, sieve the self-lubricating composite filler in S(41).

[0109] S(5) Self-lubricating composite filler surface treatment

[0110] S(51) For the granular self-lubricating composite filler screened in the S(42), the surface thereof is subjected to low-temperature chemical copper plating treatment to obtain a self-lubricating composite filler.

[0111] Example 2:

[0112] The resin-based self-lubricating grinding wheel of the present embodiment has high strength and low burn, and the raw materials of the grinding wheel include, by weight fraction, modified phenolic resin powder 13 parts, phenolic resin liquid 6 parts, hemihydrate gypsum powder 2 parts, ice crystal stone powder 3 parts, pyrite powder 1 part, corundum powder 2 parts, iron oxide powder 1 part, basalt fiber 2 parts, glass fiber 2 parts, graphite powder 1 part, self-lubricating composite filler prepared in Example 1 18 parts, F12 zirconia corundum 10 parts, F16 zirconia corundum 50 parts, and F30 zirconia corundum 20 parts.

[0113] The method for preparing the resin-based self-lubricating grinding wheel of the present embodiment includes:

[0114] (1) Raw material pretreatment

[0115] (11) The hemihydrate gypsum powder, ice crystal stone powder, pyrite powder, corundum powder, iron oxide powder, basalt fiber, glass fiber, graphite powder, and zirconia corundum abrasive are placed in a 3wt% KH560 alcohol solution and treated in an ultrasonic oscillation environment for 1.0h, with sufficient stirring during the ultrasonic process;

[0116] (12) The modified phenolic resin powder and the self-lubricating composite filler are placed in a blast drying oven and baked at 50℃ for 60h; the modified hemihydrate gypsum powder, ice crystal stone powder, pyrite powder, corundum powder, iron oxide powder, basalt fiber, glass fiber, graphite powder, and zirconia corundum abrasive in (11) are placed in a blast drying oven and dried and baked at 80℃ for 20h;

[0117] (13) The hemihydrate gypsum powder, ice crystal stone powder, pyrite powder, corundum powder, iron oxide powder, basalt fiber, glass fiber, and graphite powder in (12) are placed in a ball mill for ball milling, with a ball mill speed of 400rpm and a ball-to-material ratio of 1:0.4.

[0118] (2) Mixing

[0119] (21) The zirconia corundum abrasive weighed according to the proportion is placed in the upper pot of a double-pot countercurrent mixer, with the upper pot rotating clockwise at a speed of 60rpm and the material fork rotating counterclockwise at a speed of 20rpm, and stirring for 5min to fully mix and evenly distribute the zirconia corundum of different particle sizes, obtaining a mixed abrasive;

[0120] (22) The phenolic resin liquid weighed according to the weight ratio is added to the mixed zirconia corundum abrasive in (21), and stirring is continued for 5min to obtain a wetted zirconia corundum abrasive;

[0121] (23) Weigh the semi-hydrated gypsum powder, ice powder, pyrite powder, corundum powder, iron oxide powder, basalt fiber, glass fiber, and graphite powder after ball milling in (13), and add them to the upper pot of the double-pot countercurrent mixer. Continue stirring for 8 min. After stirring is complete, transfer the mixture to the lower pot of the double-pot countercurrent mixer;

[0122] (24) Add the modified phenolic resin powder to the lower pot of the double-pot countercurrent mixer. The lower pot rotates clockwise at 60 rpm, and the material fork rotates counterclockwise at 20 rpm. Stir for 1.5 min to evenly coat the abrasive surface with a layer of modified phenolic resin powder;

[0123] (25) Weigh the self-lubricating composite filler with an average particle size of 0.65 mm and add it to the lower pot of the double-pot countercurrent mixer. Continue stirring for 0.5 min to obtain the molding material;

[0124] (26) Pass the molding material in (25) through a 35-mesh sieve to obtain the sieve residue. Continue passing the sieve residue through an 8-mesh sieve, and the obtained sieve residue is the molding material.

[0125] (3) Pre-pressing molding

[0126] (31) Weigh the molding material in (26) and place it in a mold. Press at 50℃ and 5MPa for 5 min. This process releases gas 2 times, with a release time of 20 seconds per time;

[0127] (32) Press at 120℃ and 10MPa for 10 min. This process releases gas 5 times, with a release time of 30 seconds per time;

[0128] (33) Press at 180℃ and 10MPa for 20 min. This process releases gas 8 times, with a release time of 15 seconds per time;

[0129] After compression is complete, the resin-based grinding wheel blank is obtained after natural cooling.

[0130] (4) Curing

[0131] Place the grinding wheel blank in (33) in a forced air drying oven and cure according to the following process:

[0132] (41) Low temperature section: 60℃, baking for 1h;

[0133] (42) Medium temperature section: 120℃, baking for 2h;

[0134] (43) High temperature section: 180℃, baking for 28h;

[0135] (44) Cooling stage: After the end of section (43), the grinding wheel cools with the oven, and the high-strength low-burn resin-based self-lubricating grinding wheel is obtained after cooling.

[0136] Example 3:

[0137] The resin-based self-lubricating grinding wheel with high strength and low burn of the present example comprises, by weight parts, modified phenolic resin powder 15 parts, epoxy resin liquid 7 parts, hemihydrate gypsum powder 2 parts, ice crystal powder 1 part, pyrite powder 1 part, corundum powder 3 parts, zirconium tetrafluoride powder 4 parts, carbon fiber 1 part, glass fiber 5 parts, molybdenum disulfide powder 2 parts, self-lubricating composite filler prepared in Example 1 16 parts, F12 zirconium corundum 15 parts, F16 zirconium corundum 55 parts, F30 zirconium corundum 15 parts.

[0138] The preparation method of the resin-based self-lubricating grinding wheel with high strength and low burn of the present example comprises:

[0139] (1) Pretreatment of raw materials

[0140] (11) As in Example 2, the hemihydrate gypsum powder, ice crystal powder, pyrite powder, corundum powder, zirconium tetrafluoride powder, carbon fiber, glass fiber, molybdenum disulfide powder, and zirconium corundum abrasive in the present example are successively subjected to coupling agent modification, surface drying, and ball milling and dispersion treatment.

[0141] (12) As in Example 2, the modified phenolic resin powder in the present example is subjected to drying treatment.

[0142] (2) Mixing

[0143] (21) The zirconium corundum abrasive weighed according to the proportion is placed in the upper pot of the double-pot countercurrent mixer, the upper pot rotates clockwise at a speed of 60 rpm, the material fork rotates counterclockwise at a speed of 20 rpm, and stirring is performed for 4 min to fully mix and uniformly distribute the zirconium corundum of different particle sizes, thereby obtaining mixed abrasive;

[0144] (22) The epoxy resin liquid is weighed according to the weight ratio and added to the mixed zirconium corundum abrasive in (21), and stirring is continued for 8 min to obtain the wetted zirconium corundum abrasive;

[0145] (23) The hemihydrate gypsum powder, ice crystal powder, pyrite powder, corundum powder, zirconium tetrafluoride powder, carbon fiber, glass fiber, and molybdenum disulfide powder that have been ball-mixed in (11) are weighed and added to the upper pot of the double-pot countercurrent mixer, and stirring is continued for 8 min. After stirring is completed, the mixed material is transferred to the lower pot of the double-pot countercurrent mixer;

[0146] (24) The modified phenolic resin powder is added to the lower pot of the double-pot countercurrent mixer, the lower pot rotates clockwise at a speed of 60 rpm, the material fork rotates counterclockwise at a speed of 20 rpm, and stirring is performed for 1 min;

[0147] (25) The self-lubricating composite filler with an average particle size of 0.5 mm is added to the lower pot of the double-pot countercurrent mixer, and stirring is continued for 1 min to obtain the material to be formed;

[0148] (26) The molding material in (25) is passed through a 35-mesh sieve to obtain the sieve residue; the sieve residue is further passed through an 8-mesh sieve, and the obtained sieve residue is the molding material.

[0149] (3) Pre-pressing

[0150] (31) The molding material in (26) is weighed and placed in a mold, and is pressed at 50°C and 8MPa for 5min; the process is released twice, and the release time is 30 seconds per time;

[0151] (32) The process is pressed at 130°C and 8MPa for 15min; the process is released 5 times, and the release time is 20 seconds per time;

[0152] (33) The process is pressed at 175°C and 12MPa for 25min; the process is released 10 times, and the release time is 20 seconds per time;

[0153] After the compression is completed, the resin-based grinding wheel blank is obtained after natural cooling.

[0154] (4) Curing

[0155] The grinding wheel blank in (33) is placed in a forced air drying oven, and is cured according to the following process, specifically:

[0156] (41) Low-temperature section: 50°C, baking for 1.5h;

[0157] (42) Medium-temperature section: 120°C, baking for 2.5h;

[0158] (43) High-temperature section: 185°C, baking for 25h;

[0159] (44) Cooling stage: after the end of (43), the grinding wheel is cooled with the oven, and the high-strength low-burn resin-based self-lubricating grinding wheel is obtained after cooling.

[0160] Example 4:

[0161] The high-strength low-burn resin-based self-lubricating grinding wheel of the present embodiment comprises, by weight parts, modified phenolic resin powder 12 parts, phenolic resin liquid 6 parts, hemihydrate gypsum powder 3 parts, ice crystal stone powder 3 parts, pyrite powder 2 parts, basalt fiber 6 parts, tungsten sulfide powder 2 parts, self-lubricating composite filler prepared in Example 1 16 parts, F12 zirconia alumina 15 parts, F16 zirconia alumina 45 parts, and F30 zirconia alumina 25 parts.

[0162] The preparation method of the high-strength low-burn resin-based self-lubricating grinding wheel of the present embodiment comprises:

[0163] (1) Raw material pretreatment

[0164] (11) Put the hemihydrate gypsum powder, ice powder, pyrite powder, basalt fiber, tungsten sulfide powder, and zirconia alumina abrasive into a 2wt% KH560 alcohol solution, and treat in an ultrasonic oscillation environment for 1.0h, with sufficient stirring during the ultrasonic process;

[0165] (12) Put the modified phenolic resin powder and self-lubricating composite filler into a blast drying oven, and bake at 50°C for 50h; put the modified hemihydrate gypsum powder, ice powder, pyrite powder, basalt fiber, tungsten sulfide powder, and zirconia alumina abrasive in (11) into a blast drying oven, and dry bake at 70°C for 20h;

[0166] (13) Put the hemihydrate gypsum powder, ice powder, pyrite powder, basalt fiber, and tungsten sulfide powder in (12) into a ball mill for ball milling, with a ball mill speed of 350rpm and a ball-to-material ratio of 1:0.4.

[0167] (2) Mixing

[0168] (21) Put the zirconia alumina abrasive weighed according to the proportion into the upper pot of a double-pot countercurrent mixer, with the upper pot rotating clockwise at a speed of 60rpm and the material fork rotating counterclockwise at a speed of 20rpm, and stir for 4min to fully mix and evenly distribute the zirconia alumina abrasive of different particle sizes, obtaining a mixed abrasive;

[0169] (22) Add the phenolic resin liquid weighed according to the weight ratio to the mixed zirconia alumina abrasive in (21), and continue to stir for 7min to obtain the wetted zirconia alumina abrasive;

[0170] (23) Put the hemihydrate gypsum powder, ice powder, pyrite powder, basalt fiber, and tungsten sulfide powder ball-mixed in (13) into the upper pot of a double-pot countercurrent mixer, and continue to stir for 6min. After stirring is completed, transfer the mixed material to the lower pot of the double-pot countercurrent mixer;

[0171] (24) Put the modified phenolic resin powder into the lower pot of the double-pot countercurrent mixer, with the lower pot rotating clockwise at a speed of 60rpm and the material fork rotating counterclockwise at a speed of 20rpm, and stir for 1min;

[0172] (25) Weigh the self-lubricating composite filler with an average particle size of 0.65mm, and add it to the lower pot of the double-pot countercurrent mixer, and continue to stir for 0.5min to obtain the material to be formed;

[0173] (26) Pass the material to be formed in (25) through a 35-mesh sieve to obtain the sieve residue; continue to pass the sieve residue through an 8-mesh sieve, and the sieve residue obtained is the formed material.

[0174] (3) Pre-pressing forming

[0175] (31) The molding material in (26) is weighed and placed in a mold, and is pressed at 50°C and 6MPa for 5min; the process is vented twice, with a venting time of 15s each time;

[0176] (32) Pressing at 120°C and 8MPa for 15min; the process is vented six times, with a venting time of 20s each time;

[0177] (33) Pressing at 170°C and 15MPa for 25min; the process is vented ten times, with a venting time of 20s each time;

[0178] After the compression is completed, the resin-based grinding wheel blank is obtained after natural cooling.

[0179] (4) Curing

[0180] The grinding wheel blank in (33) is placed in a forced air drying oven, and is cured according to the following process, specifically:

[0181] (41) Low-temperature section: baking at 50°C for 1.5h;

[0182] (42) Medium-temperature section: baking at 130°C for 3h;

[0183] (43) High-temperature section: baking at 190°C for 20h;

[0184] (44) Cooling stage: after the end of (43), the grinding wheel is cooled with the oven, and a high-strength low-burn self-lubricating resin-based grinding wheel is obtained after cooling.

[0185] Comparative Example 5:

[0186] The preparation method of this example is the same as that of Example 2, except that this example does not contain self-lubricating composite fillers, and a resin-based grinding wheel is obtained.

[0187] In parts by weight, modified phenolic resin powder 13 parts, phenolic resin liquid 6 parts, hemihydrate gypsum powder 2 parts, ice crystal powder 3 parts, pyrite powder 1 part, corundum powder 2 parts, iron oxide powder 1 part, basalt fiber 2 parts, glass fiber 2 parts, graphite powder 6 parts, F12 zirconium corundum 10 parts, F16 zirconium corundum 50 parts, F30 zirconium corundum 20 parts.

[0188] Comparative Example 6:

[0189] The preparation method of this example is the same as that of Example 3, except that this example does not contain self-lubricating powder and self-lubricating composite fillers, and a resin-based grinding wheel is obtained.

[0190] Modified phenolic resin powder 15 parts by weight, epoxy resin liquid 7 parts, hemihydrate gypsum powder 2 parts, ice crystal powder 1 part, pyrite powder 1 part, corundum powder 3 parts, zirconium tetrafluoride powder 4 parts, carbon fiber 1 part, glass fiber 5 parts, F12 zirconium corundum 15 parts, F16 zirconium corundum 55 parts, F30 zirconium corundum 15 parts.

[0191] The high-strength low-burn resin-based self-lubricating grinding wheels prepared in Examples 2-4 and Comparative Examples 5 and 6 were subjected to compression strength and grinding performance tests, and the performance test results of the high-strength low-burn resin-based self-lubricating grinding wheels of the above examples were obtained, as shown in Table 1.

[0192] Table 1 Performance test results of resin-based grinding wheels prepared in Examples 2-4 and Comparative Examples 5-6

[0193]

[0194] As can be clearly seen from the results in Table 1, the addition of self-lubricating composite fillers and self-lubricating powders in the grinding wheel can ensure that the grinding wheel has good compression strength, and the grinding wheel exhibits high polishing capacity and excellent grinding ratio, while reducing the friction coefficient between the resin-based grinding wheel and the workpiece surface, thereby significantly reducing the grinding temperature, reducing the wear of the grinding wheel, and improving the surface finish of the steel rail.

[0195] During the polishing experiment of the resin-based grinding wheels prepared in Examples 2-4 and Comparative Examples 5 and 6, the results of the friction coefficient between the grinding wheel and the steel rail interface were Figure 2 The results show that under the synergistic control of self-lubricating composite fillers and self-lubricating powders, the friction coefficient between the grinding wheel and the steel rail interface is significantly reduced, thereby effectively reducing the generation of grinding heat.

[0196] The U71Mn steel rail sample polished by the resin-based steel rail polishing grinding wheel prepared in Example 2 and Comparative Example 6 was cut along the polishing direction to prepare a cross-section metallographic sample, and the cross-section metallographic structure was observed using an optical microscope, and the results were as follows Figure 3 The results show that the steel rail polishing grinding wheel prepared in Example 2 can effectively reduce the thickness of the white layer on the steel rail surface caused by grinding heat, improve the pre-fatigue of the steel rail caused by polishing, and thereby improve the surface quality of the polished steel rail and prolong the service period of the steel rail. Figure 4 The results of the electron backscatter diffraction (EBSD) crystal orientation of the steel rail cross-section after polishing by the steel rail polishing grinding wheel prepared in Example 2 show that there is no obvious preferred orientation on the surface of the polished steel rail, and there is basically no grain refinement structure (i.e. white layer), further proving that the high-strength low-burn resin-based self-lubricating grinding wheel prepared in Example 2 has good lubrication effect and effectively reduces the generation of burn defect white layer on the steel rail caused by polishing.

[0197] Although the specific embodiments of the application have been described in detail, that should not be understood as a limitation on the scope of the patent. Various modifications and equivalents can be employed without departing from the scope of the application described in the claims.

Claims

1. A high-strength, low-burn resin-based self-lubricating grinding wheel, obtained from grinding wheel raw materials through mixing, pre-pressing, and curing, characterized in that: The grinding wheel raw materials, by weight, include: 12-20 parts of resin binder, 6-8 parts of wetting agent, 6-12 parts of functional filler, 3-8 parts of reinforcing fiber, 1-3 parts of self-lubricating powder, 12-18 parts of self-lubricating composite filler, and 65-85 parts of abrasive. The self-lubricating composite filler is a composite particle with uniform particle size prepared by sequentially mixing, molding, curing, mechanical crushing, surface plating, and sieving of resin binder, reinforcing filler, lubricant, and fiber material; the lubricant in the self-lubricating composite filler is one or more of graphite powder, molybdenum disulfide powder, tungsten sulfide powder, hexagonal boron nitride powder, and fluorite powder; the surface of the self-lubricating composite filler has a large number of overhanging fibers; the surface of the self-lubricating composite filler is treated with low-temperature chemical copper plating and nickel plating; the average particle size of the self-lubricating composite filler is 0.2 to 0.5 times the average particle size of coarse abrasive in the grinding wheel.

2. The high-strength, low-burn resin-based self-lubricating grinding wheel according to claim 1, characterized in that: The resin binder is one of modified phenolic resin powder, polyimide resin powder, or bismaleimide resin powder.

3. The high-strength, low-burn resin-based self-lubricating grinding wheel according to claim 1, characterized in that: The wetting agent is one of epoxy resin liquid or phenolic resin liquid.

4. The high-strength, low-burn resin-based self-lubricating grinding wheel according to claim 1, characterized in that: The functional filler is any one or a combination of several of the following: hemihydrate gypsum powder, cryolite powder, pyrite powder, quartz powder, corundum powder, iron oxide powder, and zirconium tetrafluoride powder.

5. The high-strength, low-burn resin-based self-lubricating grinding wheel according to claim 1, characterized in that: The reinforcing fiber is one or more of the following: aramid fiber, carbon fiber, basalt fiber, glass fiber, potassium titanate whiskers, steel fiber, and copper fiber.

6. The high-strength, low-burn resin-based self-lubricating grinding wheel according to claim 1, characterized in that: The self-lubricating powder is one or more of the following: graphite powder, molybdenum disulfide powder, tungsten sulfide powder, hexagonal boron nitride powder, and fluorite powder.

7. A method for preparing a high-strength, low-burn resin-based self-lubricating grinding wheel according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Raw material pretreatment (11) The functional filler, reinforcing fiber, self-lubricating powder and abrasive are modified with silane coupling agent respectively; (12) The resin binder, self-lubricating composite filler, modified functional filler, reinforcing fiber, self-lubricating powder, and abrasive are dried. (13) After modification and drying, the functional filler, reinforcing fiber and self-lubricating powder are ball-milled and mixed for later use; (2) Mixing (21) Place the weighed abrasives into the upper pot of the double-pot countercurrent mixer and stir for 3-5 minutes to ensure that the abrasives of different particle sizes are fully mixed and uniform to obtain the mixed abrasives. (22) Weigh the wetting agent according to the weight ratio and add it to the mixed abrasive in step (21). Continue stirring for 5~8 min to obtain the wetted abrasive. (23) Weigh the functional filler, reinforcing fiber and self-lubricating powder after ball milling in step (13), add them to the upper pot of the double-pot countercurrent mixer, and continue stirring for 6 to 8 minutes so that the functional filler, reinforcing fiber and self-lubricating powder are evenly adhered to the surface of the abrasive after being moistened by the wetting agent; after stirring is completed, transfer the mixture to the lower pot of the double-pot countercurrent mixer. (24) Add the powdered resin binder to the lower pot of the double-pot countercurrent mixer and stir for 1 to 1.5 min to make the surface of the abrasive uniformly coated with a layer of resin powder. (25) Add the weighed self-lubricating composite filler to the lower pot of the double-pot countercurrent mixer and continue stirring for 0.5~1.0 min to make the self-lubricating composite filler evenly dispersed in the abrasive and obtain the material to be formed. (26) The material to be formed in step (25) is sieved. First, it is sieved through a fine mesh screen to obtain the material on the sieve. Then, the material on the sieve is sieved through a coarse mesh screen. The material under the screen is the resin grinding wheel forming material. (3) Pre-compression molding The resin grinding wheel molding material is put into the mold and pre-pressed under the pressing process to obtain the grinding wheel blank; (4) Curing The grinding wheel blank is cured and molded under a curing process to obtain a high-strength, low-burn resin-based self-lubricating grinding wheel.

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