CN114571377B - PAI resin-based grinding wheel and preparation method thereof - Google Patents

PAI resin-based grinding wheel and preparation method thereof Download PDF

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Publication number
CN114571377B
CN114571377B CN202111349545.XA CN202111349545A CN114571377B CN 114571377 B CN114571377 B CN 114571377B CN 202111349545 A CN202111349545 A CN 202111349545A CN 114571377 B CN114571377 B CN 114571377B
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China
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grinding wheel
pai resin
pai
resin
abrasive
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CN114571377A (en
Inventor
王海涛
陈文忠
陈熙
田剑书
蒋其陶
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Yixing Zerun Polymer New Material Co ltd
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Yixing Zerun Polymer New Material Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
    • B24D3/28—Resins or natural or synthetic macromolecular compounds
    • B24D3/32—Resins or natural or synthetic macromolecular compounds for porous or cellular structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D18/00—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
    • B24D18/0009—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for using moulds or presses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/34—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties
    • B24D3/342—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties incorporated in the bonding agent
    • B24D3/344—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties incorporated in the bonding agent the bonding agent being organic
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

The invention relates to a PAI resin-based grinding wheel and a preparation method thereof, wherein a slice cluster PAI resin is used as a bonding agent to be mixed with an abrasive and an acidic organic substance by adopting a prestress mixing means, and then the PAI resin-based grinding wheel is manufactured after hot molding and secondary curing; the grinding wheel abrasive prepared by the method disclosed by the invention is uniform in dispersion, higher in heat resistance, high in grinding wheel compactness, high in strength, wear-resistant, heat-resistant, good in toughness, short in processing time for grinding a workpiece, and high in surface smoothness of the workpiece after grinding.

Description

PAI resin-based grinding wheel and preparation method thereof
Technical Field
The invention relates to the technical field of high polymer resin, in particular to a PAI resin-based grinding wheel and a preparation method thereof.
Background
Grinding wheels are cutting tools made up of a number of extremely hard abrasive particles bonded by a bonding agent. Hard angular particles on the surface of the grinding wheel are called abrasive materials and play a role in cutting. The bonding material that bonds the abrasives together is referred to as a bond. The characteristics of the grinding wheel are influenced by factors such as abrasive materials, granularity, binding agent, hardness, tissues, shape, size, linear speed and the like, and each grinding wheel has a certain application range according to the sand heat property, the base material property, the self heat resistance and the like. The abrasive is the main component of the grinding wheel, directly responsible for cutting work, and has high hardness, modulus and thermal performance, and common abrasives include oxide ceramics, carbides, nitrides and the like. The binder is a substance used for binding the abrasive in the grinding wheel, the type and the property of the binder influence the strength, the heat resistance, the impact resistance, the corrosion resistance and other performances of the grinding wheel, the binder also has influence on the grinding temperature and the surface roughness of a workpiece, and common binders generally comprise ceramics, resins, rubbers, metals and the like; the resin binder is required to have high strength, good elasticity and impact resistance, but has the problems of poor heat resistance, reduced adhesive force after being heated, high brittle modulus and inapplicability to long-term storage.
At present, in precision grinding of high-hardness workpieces, in order to ensure the product quality of the final high-finish workpieces, a resin-based grinding wheel is hoped to be used as the final link of processing. The bonding agent used for the conventional diamond resin grinding wheel is mainly phenolic resin, epoxy resin and the like. The phenolic resin and the like have the following defects in the using process: (1) the heat-resistant temperature is low, the adhesive force is small, the brittleness is high, and part of diamond does not fully play a role and falls off earlier, so that the utilization rate of the diamond is reduced, and the abrasion of the grinding wheel is not resistant; (2) curing agent urotropine must be added during curing, and if the process conditions are controlled improperly, gas generated in the curing process causes air holes to appear in the grinding wheel tissue, so that the grinding wheel is sometimes scrapped; (3) the grinding wheel always emits unpleasant smell in the manufacturing and using processes of the grinding wheel; (4) when the feed amount is large, the grinding wheel is often cracked. In addition, polyimide (PI) resin-based diamond grinding wheels are also used, because the PI is selected as thermosetting resin, when the grinding wheels are prepared, forming load of a front stage and curing conditions without and with small load in a later stage are only loaded, so that the defects of poor overall compactness, low strength, wear resistance and large brittleness of the PI-based diamond grinding wheels can be caused, when a workpiece is ground, the processing time is prolonged, the processing effect is poor, and the adverse factors of high production cost and low safety coefficient are indirectly caused due to the increase of self-abrasion of the grinding wheels.
Disclosure of Invention
The PAI resin-based grinding wheel and the preparation method thereof are provided for solving the technical problems of large grinding loss, long processing time and poor processing effect caused by poor compactness, low strength, wear resistance and large brittleness of the grinding wheel made of conventional resin. The PAI resin is used as a binding agent to be mixed with the abrasive to prepare the grinding wheel with uniformly dispersed abrasive, and the grinding wheel can obtain higher strength and heat resistance after being subjected to secondary crosslinking and curing in the later period, so that the prepared grinding wheel has the advantages of high compactness, high strength, wear resistance, heat resistance, good toughness, short grinding processing time and high surface smoothness.
In order to achieve the above purpose, the invention is realized by the following technical scheme:
in another aspect, the present invention provides a method of preparing a PAI resin-based grinding wheel, comprising the steps of:
(1) Preparing PAI resin, abrasive and acid organic matter; coupling the abrasive;
(2) The materials comprise the PAI resin, the abrasive material subjected to coupling treatment and the acidic organic matters and are subjected to prestress mixing, and vacuum pumping is carried out in the prestress mixing process to generate negative pressure and heat at the same time, so that the materials which are uniformly mixed are obtained;
(3) Fixing the supporting structural member in a grinding wheel die, adding the material obtained in the step (2) for integral hot molding, and performing secondary curing at 180-380 ℃ after molding is completed to obtain the PAI resin-based grinding wheel.
Further, the PAI resin in the PAI resin-based grinding wheel accounts for 30-55wt%, the abrasive accounts for 44.7-65wt% and the acidic organic matters account for 0.3-5%.
Further, the microstructure of the PAI resin is a lamellar cluster structure.
Still further, the PAI resin is obtained according to a method for synthesizing polyamide-imide resin by water phase, wherein the ratio of the total mass of raw material acid and diamine compound to the weight of added water is controlled to be 1 (21-100) in the preparation process, and the PAI resin with a microstructure of lamellar cluster shape can be prepared. Preferably, the ratio of the total mass of the raw materials to the weight of the added water is 1 (25-80), more preferably the ratio of the total mass of the raw materials to the weight of the added water is 1 (30-50). "method for aqueous phase Synthesis of Polyamide-imide resin" referring to the disclosure of Chinese patent CN202011184708.9, the ratio of the total weight of the raw materials of trimellitic acid and diamine compounds to the weight of water disclosed in Chinese patent CN202011184708.9 is 1 (5-20), and the bulk density of the PAI resin prepared therefrom is 0.17-0.25 g/cm 3 The microstructure is not clustered in the sheet layer; PAI resin synthesized by adopting conventional organic solvent phase has a microstructure of particles with uneven size and a bulk density of at least 0.23g/cm 3 The above; in the invention, by increasing the proportion of water, the physical and chemical indexes of the resin are unchanged in the preparation process of PAI, and only the microscopic morphology of the resin is changed, so that the PAI has a lamellar cluster structure, and the bulk density is 0.07-0.11g/cm 3 Has a relatively loose bulk density, which is achievedOne reason for this is that by controlling the water to water ratio to a large proportion of the water input, the raw material monomers are swelled in the reaction process, and the raw material molecules have a larger stretching space in a large proportion of water in the swelling process, so that the microscopic morphology of the product is changed in the monomer polymerization process, and finally the PAI resin with a lamellar cluster structure is obtained. Because gaps exist among the lamellar clustered structures, the PAI with the microstructure can reserve residence positions for various inorganic abrasive materials, and the prestress mixing method provided by the invention ensures that the abrasive materials cannot generate split phases due to different densities and particle sizes, and ensures that the abrasive materials in the finally manufactured grinding wheel are uniformly distributed.
Further, the acidic organic matter is a compound with alpha-H, and the compound with alpha-H can be one or more of isocyanates, sulfonyl chlorides, aldehydes, epoxies, carboxylic acids and acid anhydrides, preferably the acidic organic matter is a carboxylic acid compound, more preferably the acidic organic matter is one or more of tartaric acid, oxalic acid, malic acid, citric acid, ascorbic acid, benzoic acid, salicylic acid and caffeic acid. The acidic organic substance is not simply understood to be a compound having an acidic pH in the broad sense of carboxylic acids, but is understood to be a compound having an alpha-H in its molecular structure, which has a certain acidity due to its relatively high activity. The acidic organic matters can promote the rapid secondary curing crosslinking reaction of PAI in the thermoforming process of preparing the grinding wheel, so that the glass transition temperature of the prepared PAI resin-based grinding wheel is increased from about 260 ℃ to more than 300 ℃, and the strength of the grinding wheel is obviously improved.
Further, the abrasive comprises diamond and silicon carbide, and the mass ratio of the diamond to the silicon carbide is (6-10): 1-3; the grain diameter of the diamond is 50-250 meshes, and the grain diameter of the diamond is 80-300 meshes; the silicon carbide is silicon carbide or a mixture of silicon carbide and boron nitride; the abrasive material also comprises metal powder, wherein the metal powder is one or more of zinc powder, tin powder, copper powder, iron powder, manganese powder and aluminum powder, the particle size of the metal powder is 600-1000 meshes, and the use amount of the metal powder accounts for 1-20wt% of the PAI resin-based grinding wheel. The metal powder can be used as a filler to fill gaps in the abrasive, and simultaneously is used as a heat conducting chain, so that the overall hardness of the prepared PAI resin-based grinding wheel can be improved, and the overall working life of the grinding wheel can be prolonged.
Further, steel balls with various diameters are adopted to be mixed with the materials in the pre-stress mixing process, the diameter range of the steel balls is 10-50mm, the mass ratio of the steel balls to the materials is (1-3): 1, the vacuum degree is-0.05 to-0.09 Mpa in the pre-stress mixing process, the heating temperature is 100-250 ℃, the mixing rotating speed is 500-3000rpm, and the mixing time is 0.5-3h. According to the invention, steel balls with different diameters are adopted to be mixed with materials under the actions of heating and negative pressure, so that water adsorbed on the surfaces of the materials can be quickly separated, on the one hand, abrasive materials are intercalated into the layers of the lamellar clustered PAI under the action of the steel balls and the negative pressure, the intercalated lamellar clustered PAI is softened under the action of heating and external force to generate vacuum state closure between the layers, the volume of composite particles is greatly contracted, the state can be regarded as that adjacent layer spaces of the lamellar clustered PAI contain single abrasive materials, and under the continuously rotating mixed state, the gravity falling stress of the steel balls presses the softened lamellar clustered PAI into a closed state containing the materials, so that the abrasive materials are uniformly dispersed and uniform monodisperse coating is realized on the abrasive materials among the lamellar clustered PAI. Compared with conventional high-speed mixing of conventional particles, the prestress mixing has the effect of being more uniform in mixing, so that the grinding wheel obtained after the grinding material is solidified shows a more stable and firm uniformly dispersed state. Under the process of prestress mixing treatment, the volume of the whole material is greatly contracted, the oxygen-containing space is reduced, the probability of oxidation reaction of the material in the high-temperature heating stage of hot molding is greatly reduced, resin is completely bonded with the abrasive during high-temperature melting, and a tough protective layer is formed on the periphery, so that the problems of sand removal and bursting caused by the reduction of the whole volume of the grinding wheel during grinding work are avoided, the working efficiency is greatly improved, and the working life of the grinding wheel is prolonged.
Further, the coupling treatment method comprises the steps of carrying out dry-method or wet-method surface modification on the abrasive and a coupling agent treatment liquid, wherein the coupling agent treatment liquid is prepared by dissolving a coupling agent in water or alcohol to prepare a treatment liquid with the mass concentration of 0.5-5wt%, the coupling agent is a silane coupling agent with the temperature resistance of more than 300 ℃, such as KH-570, KH-900, SCA-A10E, SCA-V71M and the like, the relative cost of SCA-A10E, SCA-V71M is high, the dry-method surface modification can be carried out by adopting a mixing device to directly mix the coupling agent treatment liquid with the dry abrasive and then drying, and the wet-method surface modification can be carried out by dispersing the abrasive in the coupling agent treatment liquid, carrying out stirring heating reaction and then drying;
the hot molding temperature is 200-380 ℃, the pressure is 20-100Mpa, the time is 50-150min, the specific process is that after the air in the material is exhausted through loading pressure, the gradient heating is started to 350-380 ℃, the material in the mold is kept to be heated and compactly molded for at least 60min under the heavy load pressure of 60-100Mpa, then the pressure is supplemented for 10-30min and 60-100Mpa, then the constant pressure reverse gradient cooling is carried out, and the hot molding is completed after the temperature is reduced to be lower than 100 ℃; the hot molding process is a gradient heating and gradient cooling process, wherein the heating rate and the cooling rate are 1-20 ℃/min, preferably 3-15 ℃/min, and more preferably 5-12 ℃/min;
the secondary curing concretely comprises the following steps: baking at 100-200deg.C for 30-90min, baking at 200-300deg.C for 30-3000min, baking at 150-250deg.C for 30-80min, and baking at 50-150deg.C for 20-100min, wherein the temperature rise and temperature drop rate is 1-20deg.C/min, preferably 3-15deg.C/min, and more preferably 5-12deg.C/min; the gradient heating and the gradient cooling function ensure that the formed grinding wheel has relatively stable heated temperature in a high-density state, so that expansion and contraction stress which does not exist due to the difference of temperatures among section distances can not be generated, and the stability of the whole grinding wheel structure is damaged; in addition, regarding the length of time of the secondary curing, it should be ensured that the resin can undergo sufficient intermolecular crosslinking under such conditions, so that the resin matrix has better strength and heat resistance after molding.
The surface roughening treatment can be performed manually or by means of instrument grinding, so that the roughness of the surface roughening treatment reaches a set value to obtain a larger specific surface area, and the subsequent coupling treatment can enable small metal molecules of the metal support structure to be attached to a silane coupling agent with medium molecular weight, so that the heat-resistant silane coupling agent can generate larger adhesive property to effectively adhere metal to a resin matrix during high-temperature hot melting, the effect of adhesion degree and adhesion bridge is achieved, the adhesion of the resin matrix material to the metal support structure is improved, and the stress support and heat conduction effect of the whole grinding wheel material are better.
In a final aspect the invention provides a PAI resin-based grinding wheel obtainable by the process as hereinbefore described.
The beneficial technical effects are as follows:
according to the invention, PAI with a lamellar cluster microstructure is combined with a prestress mixing technology, substances such as PAI and abrasive materials are mixed, and the abrasive materials are uniformly dispersed among lamellar cluster PAI layers and are coated by the PAI under the action of gravity of a steel ball, vacuumizing negative pressure and heating, so that the abrasive materials in the prepared grinding wheel are more uniformly dispersed.
The abrasive materials in the PAI-based resin grinding wheel prepared by the invention are uniformly dispersed, and can be coupled and bonded with structural parts with high strength, so that the PAI-based resin grinding wheel is a high-quality diamond resin grinding wheel with good self-sharpening property, difficult blockage and workpiece burn phenomenon reduction. In the practical application process of the technical field of high-speed grinding and ultra-precise grinding, the method has the remarkable characteristics of good processing effect, large grinding load, high grinding speed, long service life and the like.
Drawings
Fig. 1A is a physical view of a conventional diamond metal sintered grinding wheel, and fig. 1B is a physical view of a PAI resin-based grinding wheel.
Fig. 2 is a view showing the dispersion state of abrasive observed under a metallographic microscope for the PAI resin-based grinding wheel.
Fig. 3 is a microscopic SEM image of the platelet cluster PAI resin.
Fig. 4 is a microscopic SEM image of a conventional organic solvent phase synthesized PAI resin from the suv (Solvay) group.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The numerical values set forth in these examples do not limit the scope of the present invention unless specifically stated otherwise. Techniques, methods known to those of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values.
Example 1
A preparation method of a PAI resin-based grinding wheel comprises the following steps:
(1) Preparing materials: 45wt% of lamellar cluster PAI resin, 45wt% of silicon carbide (150 meshes), 8% of diamond (60 meshes), and 2% of acidic organic matters (ascorbic acid and salicylic acid in a mass ratio);
coupling treatment is carried out on two abrasive materials of silicon carbide and diamond: carrying out dry surface modification on the two abrasive materials and a coupling agent treatment liquid, wherein the coupling agent treatment liquid is a water-ethanol solution of SCA-A10E, the mass concentration is 3.5%, spraying the coupling agent treatment liquid into the abrasive materials which are continuously stirred according to the mass ratio of the abrasive materials to the coupling agent treatment liquid of 1:2, heating to 65 ℃ in the stirring process, continuing stirring for 1h after the coupling agent treatment liquid is completely sprayed, discharging, and drying for later use;
(2) The material comprises the lamellar cluster PAI resin, the abrasive material subjected to coupling treatment and the acidic organic matter, and is subjected to prestress mixing, and vacuum pumping is carried out in the prestress mixing process to heat the material while generating negative pressure, so that the material which is uniformly mixed is obtained, wherein the specific prestress mixing conditions are as follows: steel balls with diameters of 10mm, 20mm, 30mm and 50mm (the four steel balls with diameters are configured according to a mass ratio of 2:2:1:1) are adopted to be mixed with the materials, the mass ratio of the total mass of the steel balls to the materials is 2:1, the vacuum degree is-0.08 Mpa, the heating temperature is 280 ℃, the mixing rotating speed is 2000rpm, and the mixing time is 2h in the prestressed mixing process; after the pre-stress mixing is completed, the material is ready for use;
(3) The metal supporting structural member (the part contacted with the materials) for preparing the grinding wheel is firstly polished and then subjected to coupling treatment, wherein the polishing treatment can be manually polished by sand paper or polished by conventional polishing equipment until the surface roughness of the metal supporting structural member is greater than N11 Ra＝25 After the national standard marking, the coupling treatment is spraying treatment by adopting the coupling agent treatment liquid (the coupling agent treatment liquid is still carried out in the step 1), and then drying is carried out for standby;
fixing the polished and coupled metal supporting structural part in a grinding wheel die, adding the material uniformly mixed by the prestress in the step (2) into the area formed by the die and the metal supporting structural part, carrying out integral hot-molding, discharging air in the material by loading pressure, starting gradient heating (heating rate is set to 5-8 ℃/min) to 370 ℃, keeping the heating and compacting of the material in the die for at least 80min under the high load pressure of 10-80Mpa, then carrying out pressure compensation for 20min and 40Mpa, ensuring that the molded working body of the grinding wheel has integral compactness, high strength, grinding resistance and good toughness, then carrying out pressure relief, gradient cooling (cooling rate is set to 5-8 ℃/min) to be lower than 100 ℃, and then unloading the die to finish hot-molding, and obtaining a semi-finished product;
the semi-finished product is then subjected to secondary curing in a high temperature oven: baking at 200deg.C for 50min, baking at 250deg.C for 40min, baking at 280deg.C for 500min, baking at 230deg.C for 60min, and baking at 120deg.C for 40min, wherein the temperature rise and temperature drop are 5-8deg.C/min, and cooling to obtain PAI resin-based grinding wheel, the graph of which is shown in figure 1B.
The PAI resin-based grinding wheel prepared in this example was placed under a metallographic microscope to observe the dispersion of master batch in PAI resin, and the result is shown in fig. 2, and it is clear from fig. 2 that the dispersion of abrasive in the PAI resin matrix was very uniform.
The PAI resin with the lamellar cluster microstructure in this example was obtained by referring to the method of example 1 of Chinese patent CN202011184708.9, except that the amount of water added in the step (2) was changed to 13000g so that the weight ratio of the total mass of 212g of trimellitic acid to 220g of diphenylether diamine to 13000g of water was 1:30. As shown in fig. 3, the SEM image of the microstructure of the product PAI shows a lamellar cluster structure on the PAI in a microcosmic manner, and the microstructure is relatively uniform as shown in fig. 3. Performing an intrinsic viscosity test on the PAI of the lamellar cluster structure to determine that the intrinsic viscosity of the lamellar cluster PAI is in the range of 0.7-1 dL/g; differential scanning calorimetric analysis (DSC) is carried out on PAI of the lamellar cluster structure, and the glass transition temperature is in the range of 275-285 ℃; the PAI of the lamellar cluster structure is tested for bulk density, and the PAI of the lamellar cluster structure is measured to have bulk density of 0.07-0.11g/cm 3 Within this range, the bulk density is relatively loose, which corresponds to the SEM result of fig. 3, and macroscopically shows a smaller bulk density value due to the microscopically represented platelet cluster structure, with more gaps or voids. As shown in FIG. 4, the PAI resin synthesized by the conventional organic solvent phase has a microstructure as shown in FIG. 4, and the PAI resin synthesized by the organic solvent phase has a non-uniform particle size, and has a bulk density of at least 0.23g/cm 3 The gaps among the particles are very small; PAI resin prepared by the method disclosed in Chinese patent CN202011184708.9 with the ratio of total weight of raw materials to weight of water of 1 (5-20) has microstructure similar to that of FIG. 4 and bulk density of 0.17-0.25 g/cm 3 In between, the bulk density of the PAI resin is slightly lower than that of the PAI resin synthesized by the conventional organic solvent phase.
The water-material ratio of the PAI resin in the lamellar cluster is controlled to be (21-100) 1 in Chinese patent CN202011184708.9, the more the added water quantity is, the more loose the obtained product is, but the too much water quantity is also unsuitable to be added, preferably the water-material ratio is (30-50) 1, the change of the microscopic morphology of the PAI resin can be realized by increasing the water quantity, the PAI resin with the lamellar cluster microstructure is obtained, and the physicochemical property of the PAI resin is not changed.
Example 2
A preparation method of a PAI resin-based grinding wheel comprises the following steps:
(1) Preparing materials: 40wt% of lamellar cluster PAI resin, 32wt% of silicon carbide (200 meshes), 12% of diamond (60 meshes), 14.5% of zinc powder (800 meshes), and 1.5% of acidic organic matters (oxalic acid and tartaric acid in equal mass ratio);
coupling treatment is carried out on three abrasive materials of silicon carbide, diamond and zinc powder: carrying out dry surface modification on the two grinding materials and a coupling agent treatment liquid, wherein the coupling agent treatment liquid is a water-ethanol solution of SCA-V71M, the mass concentration is 5%, and according to the mass ratio of the grinding materials to the coupling agent treatment liquid of 1:3, spraying the coupling agent treatment liquid into the grinding materials which are continuously stirred, wherein the heating temperature is 65 ℃ in the stirring process, continuing to stir for 2 hours after the coupling agent treatment liquid is completely sprayed, discharging, and drying for later use;
(2) The material comprises the lamellar cluster PAI resin, the abrasive material subjected to coupling treatment and the acidic organic matter, and is subjected to prestress mixing, and vacuum pumping is carried out in the prestress mixing process to heat the material while generating negative pressure, so that the material which is uniformly mixed is obtained, wherein the specific prestress mixing conditions are as follows: steel balls with diameters of 10mm, 20mm, 30mm and 50mm (the four steel balls with diameters are configured according to a mass ratio of 2:2:1:1) are adopted to be mixed with the materials, the mass ratio of the total mass of the steel balls to the materials is 2:1, the vacuum degree is-0.09 Mpa, the heating temperature is 280 ℃, the mixing rotating speed is 1500rpm, and the mixing time is 2.5h in the prestressed mixing process; after the pre-stress mixing is completed, the material is ready for use;
(3) The metal supporting structural member (the part contacted with the material) for preparing the grinding wheel is firstly polished and then subjected to coupling treatment, wherein the polishing treatment can be manually polished by sand paper or conventional polishingGrinding the metal supporting structural member by using grinding equipment until the surface roughness of the metal supporting structural member is greater than N11 Ra＝25 After the national standard marking, the coupling treatment is spraying treatment by adopting the coupling agent treatment liquid (the coupling agent treatment liquid is still carried out in the step 1), and then drying is carried out for standby;
fixing the polished and coupled metal supporting structural part in a grinding wheel die, adding the material uniformly mixed by the prestress in the step (2) into the area formed by the die and the metal supporting structural part, carrying out integral hot die forming, discharging air in the material by loading pressure, starting gradient heating (heating rate is set to 5-8 ℃/min) to 360 ℃, keeping the heating and compacting of the material in the die for at least 90min under the high load pressure of 10-80Mpa, then carrying out pressure compensation for 10min and 40Mpa, ensuring that the formed working body of the grinding wheel has integral compactness, high strength, grinding resistance and good toughness, then carrying out pressure relief, gradient cooling (cooling rate is set to 5-8 ℃/min) to be lower than 100 ℃, and then unloading the die to finish hot die forming, and obtaining a semi-finished product;
the semi-finished product is then subjected to secondary curing in a high temperature oven: baking at 200 ℃ for 70min, baking at 220 ℃ for 50min, baking at 260 ℃ for 500min, baking at 220 ℃ for 80min and baking at 120 ℃ for 60min, wherein the process is a gradient heating and gradient cooling process, the heating rate and cooling rate are 5-8 ℃/min, and finally cooling is carried out to obtain the PAI resin-based grinding wheel.
The platelet-cluster PAI resin in this example was the same as in example 1, except that the water-to-material ratio was controlled to be 50:1 during the preparation.
Comparative example 1
The preparation method of the PAI resin-based grinding wheel of the embodiment is the same as that of the embodiment 1, except that the PAI resin adopted is the PAI resin prepared in the embodiment 1 of Chinese patent CN202011184708.9 (namely, the water-to-material ratio is 10:1).
Comparative example 2
The preparation method of the PAI resin-based grinding wheel of this example was the same as in example 1, except that PAI (available from Suwei group) was used as PAI synthesized from an organic solvent phase.
Comparative example 3
The preparation method of the PAI resin-based grinding wheel in this example was the same as that in example 1, except that the materials were subjected to conventional high-speed mixing (no vacuum suction, no steel ball added), the rotation speed of the high-speed mixing was 3000rpm, and other conditions such as heating temperature, mixing time, etc. in the high-speed mixing process were the same as those in example 1.
Comparative example 4
The preparation method of the PAI resin-based grinding wheel of this example is the same as that of example 1, except that no vacuum to negative pressure is applied during the pre-stress mixing process.
Comparative example 5
The preparation method of the PAI resin-based grinding wheel of this example is the same as that of example 1, except that no steel ball is added during the pre-stress mixing process.
Comparative example 6
The preparation method of the PAI resin-based grinding wheel of this example was the same as in example 1, except that no acidic substance was added and no secondary curing was performed.
Example 3
The PAI resin-based grinding wheels prepared in examples 1-2 and comparative examples 1-5 above were applied to process 99% alumina (Al 2 O 3 ) Ceramic tube (the hardness of the tube material is close to that of diamond), the length of the tube is 100mm, the inner diameter is 89mm, and the tube needs to be processed to the inner diameter of 95mm.
The grinding wheel dimensions above: the outer diameter is 80mm, the thickness is 20mm, and the thickness of a grinding wheel working layer (which refers to a working layer containing PAI resin matrix and abrasive materials) is 10mm.
The grinding wheel pair above was made of 99% alumina (Al 2 O 3 ) The grinding time of the ceramic tube, the abrasion of the outer ring of the grinding wheel, the service life of the material (namely 99% alumina ceramic) and other performances are tested, and the performance is shown in a table 1.
TABLE 1 Properties of grinding wheels obtained in examples 1-2 and comparative examples 1-5
( And (3) injection: the diamond metal sintered grinding wheel is shown in figure 1A )
As shown in Table 1, the invention adopts the lamellar cluster PAI as the binder, adds the abrasive and the acid to perform prestress mixing and then performs hot molding, and then performs secondary curing to obtain the PAI resin-based grinding wheel, the grinding time of the grinding wheel obtained by the invention on a workpiece is shorter, only about 20 minutes is required, the surface finish of the grinding wheel after grinding is still very good, no grinding marks are seen, the abrasion loss of the outer ring of the grinding wheel is very low and less than 0.15mm, the service life of the grinding wheel on 99% alumina ceramic is at least 120, and the grinding wheel has higher working efficiency and longer service life.
The bonding agent adopted by the grinding wheel of the comparative example 1 is PAI prepared by water-to-material ratio of 10:1, the grinding wheel of the comparative example 2 is PAI synthesized by conventional organic solvent phase, the microstructure of the PAI and the PAI does not have a lamellar cluster structure, the grinding time of the grinding wheel prepared by the PAI to a workpiece is longer by at least 25 minutes, the abrasion loss of the outer ring of the grinding wheel is slightly larger than that of the grinding wheel provided by the invention, and the service life is shorter.
The data of comparative examples 3 to 5 shows that the abrasive cannot be uniformly dispersed between the layer of the lamellar clustered PAIs due to the incomplete adoption of the optimized prestress mixing means, so that the technical effect of the uniform monodisperse coating state achieved by the invention cannot be achieved, the abrasive is unevenly dispersed, the bonding degree of the resin and the abrasive is affected during high-temperature melting, a tough protective layer cannot be formed at the periphery, and the sand removal is generated during the grinding operation, and the sand removal is carried out by the pure PAI resin and ceramic, so that the problem that the whole grinding wheel is not wear-resistant is generated. The grinding wheel of comparative example 6 was unable to be secondarily cured without adding an acidic substance, and the grinding wheel without being secondarily cured had poor heat resistance.
The invention adopts the means of prestress mixing to greatly improve the service life of the grinding wheel, which benefits from the fact that the prestress mixing means can more uniformly disperse the grinding material in the resin matrix, thereby realizing the monodispersion effect of the particles.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (6)

1. The preparation method of the PAI resin-based grinding wheel is characterized by comprising the following steps of:
(1) Preparing PAI resin, abrasive and acid organic matter; coupling the abrasive;
the acidic organic matter is a compound with alpha-H;
the microstructure of the PAI resin is a lamellar cluster structure, and the preparation method comprises the following steps: the PAI resin is obtained according to a method for synthesizing polyamide-imide resin by water phase, wherein the weight ratio of the total mass of raw material acid and diamine compound to the added water is controlled to be 1 (30-50) in the preparation process, and the PAI resin with a microstructure of lamellar cluster can be prepared;
(2) The materials comprise the PAI resin, the abrasive material subjected to coupling treatment and the acidic organic matters and are subjected to prestress mixing, and vacuum pumping is carried out in the prestress mixing process to generate negative pressure and heat at the same time, so that the materials which are uniformly mixed are obtained; the steel balls with various diameters are mixed with the materials in the pre-stress mixing process, the diameter range of the steel balls is 10-50mm, the mass ratio of the steel balls to the materials is (1-3): 1, the vacuum degree is-0.05 to-0.09 Mpa in the pre-stress mixing process, the heating temperature is 100-250 ℃, the mixing rotating speed is 500-3000rpm, and the mixing time is 0.5-3h;
(3) Fixing the supporting structural member in a grinding wheel die, adding the materials uniformly mixed in the step (2) for integral hot molding, and performing secondary curing at 180-380 ℃ after molding is completed to obtain the PAI resin-based grinding wheel;
the PAI resin-based grinding wheel comprises 30-55wt% of PAI resin, 44.7-65wt% of abrasive and 0.3-5% of acidic organic matters.
2. The method for preparing the PAI resin-based grinding wheel according to claim 1, wherein the acidic organic matters are one or more of isocyanate compounds, sulfonyl chloride compounds, aldehyde compounds, epoxy compounds and acid anhydride compounds.
3. The method of preparing a PAI resin-based grinding wheel according to claim 1, wherein the abrasive comprises diamond and diamond grit, the mass ratio of diamond to diamond grit being (6-10): (1-3); the grain diameter of the diamond is 50-250 meshes, and the grain diameter of the diamond is 80-300 meshes; the silicon carbide is silicon carbide or a mixture of silicon carbide and boron nitride;
the abrasive material also comprises metal powder, wherein the metal powder is one or more of zinc powder, tin powder, copper powder, iron powder, manganese powder and aluminum powder, the particle size of the metal powder is 600-1000 meshes, and the use amount of the metal powder accounts for 1-20wt% of the PAI resin-based grinding wheel.
4. The preparation method of the PAI resin-based grinding wheel according to claim 1, wherein the coupling treatment method is characterized in that the abrasive and a coupling agent treatment liquid are subjected to dry-method or wet-method surface modification, the coupling agent treatment liquid is prepared by dissolving a coupling agent in water or alcohol to prepare a treatment liquid with the mass concentration of 0.5-5wt%, and the coupling agent is a silane coupling agent resistant to more than 300 ℃.
5. The method for preparing a PAI resin-based grinding wheel according to claim 1, wherein the temperature of the hot molding is 200-380 ℃, the pressure is 20-100Mpa, and the time is 50-150min;
the secondary curing concretely comprises the following steps: baking at 100-200deg.C for 30-90min, baking at 200-300deg.C for 30-3000min, baking at 150-250deg.C for 30-80min, and baking at 50-150deg.C for 20-100min;
the specific processes of the hot molding and the secondary curing are gradient heating and gradient cooling processes, and the heating rate and the cooling rate are 1-20 ℃/min;
the part of the supporting structural member contacted with the material is subjected to surface roughening treatment and then coupling treatment.
6. PAI resin-based grinding wheel manufactured by the manufacturing method according to any one of claims 1 to 5.
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US3471276A (en) * 1966-11-02 1969-10-07 Du Pont Peripheral abrasive wheels with composite rims
GB0408338D0 (en) * 2004-04-14 2004-05-19 3M Innovative Properties Co Abrasive articles, compositions, and methods of making the same
JP2007105817A (en) * 2005-10-12 2007-04-26 Soken:Kk Resin grinding wheel
JP5447188B2 (en) * 2010-05-31 2014-03-19 日立金属株式会社 Insulating paint and insulated wire using the same
CN102601745B (en) * 2012-03-22 2014-06-11 湖南大学 Preparation method of resin binder diamond abrasive product used for accurate grinding
CN105803248B (en) * 2016-03-10 2018-01-12 江苏耐尔特钻石有限公司 A kind of preparation method of hybrid superhard honing stone
CN108911515A (en) * 2018-08-01 2018-11-30 苏州福莱威封装技术有限公司 Glass powder with low melting point, glass powder slurry and preparation method thereof and panel encapsulating structure

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