CN114571377A - PAI resin-based grinding wheel and preparation method thereof - Google Patents
PAI resin-based grinding wheel and preparation method thereof Download PDFInfo
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- CN114571377A CN114571377A CN202111349545.XA CN202111349545A CN114571377A CN 114571377 A CN114571377 A CN 114571377A CN 202111349545 A CN202111349545 A CN 202111349545A CN 114571377 A CN114571377 A CN 114571377A
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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
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- 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
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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
- B24D3/34—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
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- 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
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention relates to a PAI resin-based grinding wheel and a preparation method thereof, wherein PAI resin in a lamellar cluster form is used as a binding agent, mixed with grinding materials and acidic organic matters by adopting a pre-stress mixing means, subjected to hot compression molding and secondary curing to prepare the PAI resin-based grinding wheel; the grinding wheel abrasive material prepared by the method is uniformly dispersed, has higher heat resistance, high density, high strength, wear resistance, heat resistance and good toughness, has short processing time for grinding the workpiece, and has high surface smoothness of the ground workpiece.
Description
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 of a plurality of extremely hard abrasive particles bonded together by a binder. The 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 called a bond. The characteristics of the grinding wheel are influenced by factors such as grinding materials, granularity, bonding agents, hardness, tissues, shapes, sizes, linear speed and the like, and each grinding wheel has a certain application range according to the heat property of a sand mold, the property of a base material, the self heat resistance and the like. The abrasive is the main component of the grinding wheel, is directly responsible for cutting work, and has high hardness, modulus and thermal property, and common abrasives are oxide ceramics, carbide, nitride and the like. The bonding agent is a substance used for bonding abrasive in the grinding wheel, the type and the property of the bonding agent influence the strength, the heat resistance, the impact resistance, the corrosion resistance and other performances of the grinding wheel, the bonding agent also influences the grinding temperature and the workpiece surface roughness, and common bonding agents generally comprise ceramics, resins, rubbers, metals and the like; among them, resin binders are required to have high strength, good elasticity and impact resistance, but have problems of poor heat resistance, reduced adhesion after exposure to temperature, large brittle modulus, and unsuitability for long-term storage.
At present, when a high-hardness workpiece is precisely ground, a resin-based grinding wheel is expected to be adopted as a final link of processing in order to ensure the quality of a final high-finish workpiece product. The conventional diamond resin grinding wheel mainly uses phenolic resin, epoxy resin and the like as a binding agent. The phenolic resin and the like have the following defects in the using process: firstly, the heat-resistant temperature is not high, the adhesive force is small, the brittleness is large, and partial diamonds fall off early without fully exerting the function, so that the utilization rate is reduced, and the abrasion resistance of the grinding wheel is represented; secondly, a curing agent urotropine is added during curing, and if the process conditions are improperly controlled, gas generated in the curing process causes pores to appear in the grinding wheel tissue, so that the grinding wheel is sometimes scrapped; no matter in the manufacturing or using process of the grinding wheel, the grinding wheel often gives off unpleasant odor; fourthly, when the feed amount is large, the grinding wheel is cracked frequently. In addition, the Polyimide (PI) resin-based diamond grinding wheel is also provided, and the PI selected is thermosetting resin, so that the conditions that the former section forming load and the later section non-load and small-load curing can be only loaded during the grinding wheel preparation are determined, the defects of poor integral compactness, low strength, poor wear resistance and high brittleness of the PI-based diamond grinding wheel can be caused, the processing time is prolonged and the processing effect is poor when a workpiece is ground, and the adverse factors of production cost improvement and safety factor reduction are indirectly caused due to the increase of the self-abrasion loss of the grinding wheel.
Disclosure of Invention
The PAI resin-based grinding wheel and the preparation method thereof are provided in order to solve the technical problems of large grinding loss, long processing time and poor processing effect caused by poor density, low strength, no wear resistance and large brittleness of the grinding wheel made of conventional resin. The PAI resin is used as a bonding agent to be mixed with the grinding material to prepare the grinding wheel with uniformly dispersed grinding material, and higher strength and heat resistance can be obtained after the post-secondary cross-linking and curing, so that the prepared grinding wheel has high density, high strength, wear resistance, heat resistance, good toughness, short grinding time and high surface smoothness.
In order to achieve the purpose, the invention is realized by the following technical scheme:
in another aspect, the present invention provides a PAI resin-based grinding wheel comprising the steps of:
(1) preparing PAI resin, abrasive and acidic organic matter; performing coupling treatment on the abrasive;
(2) pre-stress mixing materials including the PAI resin, the coupled abrasive and the acidic organic matter, and heating while vacuumizing in the process of pre-stress mixing to generate negative pressure to obtain uniformly mixed materials;
(3) and (3) fixing the supporting structural part in a grinding wheel die, adding the material obtained in the step (2) for integral hot-die forming, and after forming is completed, carrying out secondary curing at 180-380 ℃ to obtain the PAI resin-based grinding wheel.
Further, the PAI resin accounts for 30-55 wt% of the PAI resin, 44.7-65 wt% of the abrasive and 0.3-5 wt% of the acidic organic matter in the PAI resin-based grinding wheel.
Further, the PAI resin has a microstructure of lamellar cluster structure.
Still further, the PAI resin is obtained by a method for aqueous-phase synthesis of a polyamide-imide resin, wherein the total mass of the raw material acid and the diamine compound and the weight of the added water are controlled during the preparationThe amount ratio is 1 (21-100), and PAI resin with a microstructure of lamellar cluster 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). The PAI is prepared by referring to the content disclosed in the Chinese patent CN202011184708.9, the weight ratio of the total weight of the raw material of the trimellitic acid and the diamine compound to the weight of water disclosed in the Chinese patent CN202011184708.9 is 1 (5-20), and the bulk density of the prepared PAI resin is 0.17-0.25 g/cm3In between, the microstructure is not lamellar clustering; the PAI resin synthesized by the conventional organic solvent phase has the microscopic morphology of granules with uneven sizes, and the bulk density is at least 0.23g/cm3The above; in the invention, the proportion of water is increased, so that the overall physical and chemical indexes of the resin are not changed in the PAI preparation process, the microstructure of the resin is only changed, the obtained PAI is in a lamellar cluster structure, and the bulk density is 0.07-0.11g/cm3The reason for obtaining the result is that the raw material monomer is swelled in the reaction process by controlling the large proportion of water input to the water-material ratio, and the raw material molecules have larger stretching space in the large proportion of water in the swelling process, so that the micro-morphology of the product is changed in the monomer polymerization process, and finally the PAI resin with the lamellar cluster structure is obtained. Because gaps exist among the lamellar cluster structures, PAI with the microstructure can reserve standing positions for various inorganic grinding materials, and the grinding materials can not generate phase separation due to different densities and particle sizes by matching with the prestress mixing method, and the grinding materials in the finally manufactured grinding wheel are ensured to be uniformly distributed.
The acidic organic substance is a compound having α -H, and the compound having α -H may be one or more of isocyanates, sulfonyl chlorides, aldehydes, epoxies, carboxylic acids, and acid anhydrides, for example, and preferably the acidic organic substance is a carboxylic acid compound, and more preferably the acidic organic substance 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 a carboxylic acid in a broad sense, but may be a compound having α -H in its molecular structure, and α -H has a certain acidity due to its high activity. The acidic organic matter can promote the PAI to generate rapid secondary curing crosslinking reaction in the thermoforming process for preparing the grinding wheel, so that the glass transition temperature of the prepared PAI resin-based grinding wheel can be increased from about 260 ℃ to over 300 ℃, and meanwhile, the strength of the grinding wheel is obviously improved.
Further, the abrasive material comprises diamond and carborundum, and the mass ratio of the diamond to the carborundum is (6-10) to (1-3); the grain size of the diamond is 50-250 meshes, and the grain size of the carborundum is 80-300 meshes; the carborundum is silicon carbide or a mixture of silicon carbide and boron nitride; the grinding 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 consumption of the metal powder accounts for 1-20 wt% of the PAI resin-based grinding wheel. The metal powder can be used as a filler to fill gaps in the grinding material and also can be used as a heat conduction chain, so that the overall hardness of the PAI resin-based grinding wheel can be improved, and the overall service life of the grinding wheel can be prolonged.
Further, steel balls with various diameters are adopted to be mixed with the material in the process of pre-stress mixing, the diameter range of the steel balls is 10-50mm, the mass ratio of the steel balls to the material is (1-3):1, the vacuum degree is-0.05-0.09 Mpa, the heating temperature is 100-250 ℃, the mixing speed is 500-3000rpm, and the mixing time is 0.5-3h in the process of pre-stress mixing. According to the invention, steel balls with different diameters are mixed with materials under the action of heating and negative pressure, so that water adsorbed on the surfaces of the materials can be quickly separated, on the other hand, the abrasive enters the interlayer of the PAI under the action of the steel balls and the negative pressure, the interlayer vacuum state is closed after the PAI is softened under the action of heating and external force, the size of composite particles is greatly shrunk, the state can be regarded as that the PAI is contained in the space of the adjacent layer of the PAI, and in the mixed state of continuous rotation, the PAI is pressed into a tight state containing materials by the gravity falling stress of the steel balls, so that the abrasive is uniformly dispersed and uniformly and singly dispersed and coated between the PAI layers. Compared with the conventional high-speed mixing of conventional particles and other means, the prestress mixing has the effect of more uniform mixing, so that the grinding wheel obtained after the grinding material is solidified shows a more stable and firmer uniformly dispersed state. Under the process of prestress mixed treatment, the volume of the whole material is greatly shrunk, the space containing oxygen is reduced, the probability of oxidation reaction of the material in the high-temperature heating stage of hot die pressing forming is greatly reduced, resin is completely bonded with grinding materials during high-temperature hot melting, and a tough protective layer is formed on the periphery of the resin, so that the problems of desanding and bursting of the grinding wheel caused by the reduction of the whole volume can be avoided during grinding, the working efficiency is greatly improved, and the service 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 solution, wherein the coupling agent treatment solution is prepared by dissolving a coupling agent in water or alcohol to prepare a treatment solution with the mass concentration of 0.5-5 wt%, 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 the SCA-A10E and the SCA-V71M is high, the coupling agent treatment solution can resist the high temperature to 400 ℃, the dry method surface modification can adopt mixing equipment to directly mix and dry the coupling agent treatment solution with the dry abrasive and then dry the dry abrasive, and the wet method surface modification can adopt the dry method of dispersing the abrasive in the coupling agent treatment solution to stir, heat and react and then dry the abrasive;
the temperature of the hot compression molding is 200-380 ℃, the pressure is 20-100Mpa, and the time is 50-150min, the specific process is that after air in the material is exhausted by loading pressure, the temperature is increased to 350-380 ℃ in a gradient manner, the material in the mold is kept heated and compacted and molded for at least 60min under the large 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 mold is removed after the temperature is reduced to be lower than 100 ℃ to complete the hot compression molding; the hot die pressing molding process is a gradient heating and gradient cooling process, the heating rate and the cooling rate are 1-20 ℃/min, the heating rate and the cooling rate are preferably 3-15 ℃/min, and the heating rate and the cooling rate are more preferably 5-12 ℃/min;
the secondary curing process comprises the following specific steps: baking at 200 ℃ for 30-90min at 100-; the functions of gradient temperature rise and gradient temperature drop are to ensure that the formed grinding wheel has relatively stable heating temperature in a high-density state, so that the expansion and contraction stress which should not exist due to thermal expansion and cold contraction caused by different temperatures of cross section distances can be avoided, and the stability of the whole grinding wheel structure is damaged; in addition, regarding the problem of long time of secondary curing, the resin should be ensured to be capable of performing sufficient intermolecular crosslinking under the condition, so that the resin matrix has better strength and heat resistance after molding.
The part of the supporting structural member, which is in contact with the material, needs to be subjected to surface roughening treatment and then subjected to coupling treatment, wherein the surface roughening treatment can be performed by manual grinding or instrument grinding, so that the roughness of the part reaches a set value, and a larger specific surface area is obtained, and the subsequent coupling treatment can enable metal small molecules of the metal supporting structural member to be attached with a layer of silane coupling agent with medium molecular weight, so that the heat-resistant silane coupling agent generates larger adhesion performance during high-temperature hot melting to effectively adhere the metal and a resin matrix, plays a role in adhesion degree and adhesion bridge, increases the adhesion of the resin matrix material to the metal supporting structural member, and enables the stress supporting and heat conduction effects of the whole material of the grinding wheel to be better.
In a final aspect of the present invention, there is provided a PAI resin-based grinding wheel obtained by the above-mentioned production method.
The beneficial technical effects are as follows:
the PAI with the lamellar clustering microstructure is combined with the prestress mixing technology to mix the PAI with the grinding materials and the like, so that the grinding materials are uniformly dispersed among the lamellar clustering PAI layers and are coated by the PAI under the action of gravity of the steel balls, the action of vacuum pumping negative pressure and the heating action, and the grinding materials in the prepared grinding wheel are more uniformly dispersed.
The PAI-based resin grinding wheel prepared by the invention has the advantages that the abrasive material is uniformly dispersed, the PAI-based resin grinding wheel can be coupled and bonded with a structural part at high strength, and the PAI-based resin grinding wheel is a high-quality diamond resin grinding wheel which has good self-sharpening performance, is not easy to block and reduces the burning phenomenon of a workpiece. In the practical application process in the technical field of high-speed grinding and ultra-precision grinding, the remarkable characteristics of good processing effect, large grinding load, high grinding speed, long service life and the like are shown.
Drawings
Fig. 1A is a schematic representation of a conventional diamond metal sintered grinding wheel, and fig. 1B is a schematic representation of a PAI resin-based grinding wheel.
FIG. 2 is a view showing the dispersion state of the abrasive grains observed under a metallographic microscope for a PAI resin-based grinding wheel.
FIG. 3 is a microscopic SEM image of lamellar clustered PAI resin.
Fig. 4 is a microscopic SEM image of a conventional organic solvent phase synthesized PAI resin, available from sumay (Solvay) group.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely in the following description with reference to the embodiments of the present invention and the accompanying drawings. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Unless specifically stated otherwise, the numerical values set forth in these examples do not limit the scope of the invention. Techniques, methods known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
Example 1
A PAI resin-based grinding wheel manufacturing method includes the following steps:
(1) preparing materials: 45 wt% of lamellar clustered PAI resin, 45 wt% of silicon carbide (150 meshes), 8 wt% of diamond (60 meshes) and 2 wt% of acidic organic matters (ascorbic acid and salicylic acid in equal mass ratio);
coupling two kinds of grinding materials of silicon carbide and diamond: carrying out dry surface modification on the two kinds of grinding materials and the coupling agent treatment liquid, wherein the coupling agent treatment liquid is a water-ethanol solution of SCA-A10E, the mass concentration of the coupling agent treatment liquid is 3.5%, the coupling agent treatment liquid is sprayed into the continuously stirred grinding materials in at least 3 batches according to the mass ratio of the grinding materials to the coupling agent treatment liquid of 1:2, the heating temperature is 65 ℃ in the stirring process, after the coupling agent treatment liquid is completely sprayed, the stirring is continued for 1 hour, and the discharging and drying processes are carried out for later use;
(2) include the material the lamella form cluster PAI resin, coupling treatment the abrasive material and acidic organic matter carries out the prestressing force and mixes the in-process that the prestressing force mixes carries out the evacuation and makes the heating when producing the negative pressure, obtains the material of misce bene, and the condition that specific prestressing force mixes is: mixing steel balls with the diameters of 10mm, 20mm, 30mm and 50mm (the four steel balls with the diameters are configured according to the mass ratio of 2:2:1: 1) with the materials, wherein 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 speed is 2000rpm, and the mixing time is 2 hours in the pre-stress mixing process; mixing the prestress for later use;
(3) grinding a metal supporting structural part (a part contacted with the material) for preparing the grinding wheel firstly, and then performing coupling treatment, wherein the grinding treatment can be performed by manually grinding sand paper or grinding the metal supporting structural part by using conventional grinding equipment until the surface roughness of the metal supporting structural part is more than N11Ra＝25After the national standard is marked, the coupling treatment is to adopt a coupling agentSpraying treatment of the treatment liquid (the coupling agent treatment liquid is still carried out in the step 1), and then drying for later use;
fixing the metal supporting structural part subjected to polishing and coupling treatment in a grinding wheel mold, adding the material uniformly pre-stressed and mixed in the step (2) into an area formed by the mold and the metal supporting structural part, carrying out integral hot compression molding, after exhausting air in the material by loading pressure, starting gradient temperature rise (the temperature rise rate is set to be 5-8 ℃/min) to 370 ℃, keeping the material in the mold heated and densely molded for at least 80min under the large load pressure of 10-80Mpa, then carrying out pressure supplement of 20min and 40Mpa, ensuring that a formed working body of the grinding wheel has integral compactness, high strength, grinding resistance and good toughness, then carrying out pressure relief, and carrying out gradient temperature reduction (the temperature reduction rate is set to be 5-8 ℃/min) to be lower than 100 ℃, and then unloading the mold to complete hot compression molding and obtaining a semi-finished product;
and then carrying out secondary curing on the semi-finished product in a high-temperature oven: baking at 200 ℃ for 50min, baking at 250 ℃ for 40min, baking at 280 ℃ for 500min, baking at 230 ℃ for 60min and baking at 120 ℃ for 40min, wherein the processes are gradient heating and gradient cooling processes, the heating rate and the cooling rate are 5-8 ℃/min, and finally cooling to obtain the PAI resin-based grinding wheel, wherein the physical diagram of the prepared PAI resin-based grinding wheel is shown in figure 1B.
The PAI resin-based grinding wheel obtained in this example was placed under a metallographic microscope to observe the dispersion of the master batch in the PAI resin, and as a result, as shown in FIG. 2, it was found from FIG. 2 that the dispersion of the abrasive in the PAI resin matrix was very uniform.
As for PAI resin having a lamellar cluster microstructure in this example, refer to the method of example 1 of Chinese patent CN202011184708.9, except that 13000g of water was added in step (2) and the ratio of the total mass of 212g of trimellitic acid and 220g of diphenyl ether diamine to 13000g of water was changed to 1: 30. The SEM image of the PAI product is shown in FIG. 3, and it can be seen from FIG. 3 that the PAI has a lamellar cluster structure on the micro scale, and the microstructure is relatively uniform. Performing intrinsic viscosity test on PAI with a lamellar cluster structure, and measuring that the intrinsic viscosity of the lamellar cluster PAI is in the range of 0.7-1 dL/g; differential Scanning Calorimetry (DSC) of PAI in lamellar cluster configuration, with glassThe glass transition temperature is 275-285 ℃; PAI with lamellar cluster structure is subjected to bulk density test, and the PAI with lamellar cluster structure is measured to be 0.07-0.11g/cm3Within the range, the bulk density is relatively loose, which corresponds to the SEM results of fig. 3, and since the sheet cluster structure is microscopically represented, there are relatively many gaps or voids, and macroscopically, the bulk density value is relatively small. While the conventional PAI resin synthesized in the organic solvent phase has a microstructure shown in FIG. 4, it can be seen from FIG. 4 that the PAI resin synthesized in the organic solvent phase has a non-uniform particle size and a bulk density of at least 0.23g/cm3Above, the voids between the particles are small; the PAI resin prepared from the Chinese patent CN202011184708.9 with the ratio of the total weight of the raw materials to the weight of water being 1 (5-20) has a microstructure similar to that of FIG. 4 and a bulk density of 0.17-0.25 g/cm3In comparison with PAI resins synthesized in conventional organic solvent phases, the bulk density is somewhat lower.
The PAI resin in lamellar cluster form can be obtained by controlling the water-material ratio in CN202011184708.9 to be (21-100):1, the product obtained by adding more water is looser, but the addition of excessive water is not suitable, preferably the water-material ratio is (30-50):1, the change of the microstructure of the PAI resin can be realized by increasing the water consumption, the PAI resin with lamellar cluster microstructure can be obtained, and the physical and chemical properties of the PAI resin are not changed.
Example 2
A PAI resin-based grinding wheel manufacturing method includes the following steps:
(1) preparing materials: 40 wt% of lamellar clustered PAI resin, 32 wt% 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 three grinding materials of silicon carbide, diamond and zinc powder: carrying out dry surface modification on the two kinds of grinding materials and the coupling agent treatment liquid, wherein the coupling agent treatment liquid is a water-ethanol solution of SCA-V71M, the mass concentration of the coupling agent treatment liquid is 5%, the coupling agent treatment liquid is sprayed into the continuously stirred grinding materials in at least 3 batches according to the mass ratio of the grinding materials to the coupling agent treatment liquid of 1:3, the heating temperature is 65 ℃ in the stirring process, after the coupling agent treatment liquid is completely sprayed, the stirring is continued for 2 hours, discharging is carried out, and the drying is carried out for later use;
(2) include the material the lamella form cluster PAI resin, coupling treatment the abrasive material and acidic organic matter carries out the prestressing force and mixes the in-process that the prestressing force mixes carries out the evacuation and makes the heating when producing the negative pressure, obtains the material of misce bene, and the condition that specific prestressing force mixes is: mixing steel balls with the diameters of 10mm, 20mm, 30mm and 50mm (the four steel balls with the diameters are configured according to the mass ratio of 2:2:1: 1) with the materials, wherein 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 speed is 1500rpm, and the mixing time is 2.5 hours in the pre-stress mixing process; after the pre-stress mixing is completed, the mixture is ready for use;
(3) grinding a metal supporting structural part (a part contacted with the material) for preparing the grinding wheel firstly, and then performing coupling treatment, wherein the grinding treatment can be performed by manually grinding sand paper or grinding the metal supporting structural part by using conventional grinding equipment until the surface roughness of the metal supporting structural part is more than N11Ra＝25After the national standard is marked, the coupling treatment is spraying treatment by using a coupling agent treatment liquid (the coupling agent treatment liquid is still carried out in the step 1), and then drying is carried out for later use;
fixing the metal supporting structural part subjected to polishing and coupling treatment in a grinding wheel mold, adding the material uniformly mixed with the prestress in the step (2) into an area formed by the mold and the metal supporting structural part, carrying out integral hot-die pressing molding, after exhausting air in the material by loading pressure, starting gradient temperature rise (the temperature rise rate is set to be 5-8 ℃/min) to 360 ℃, keeping the material in the mold heated and densely molded for at least 90min under the large load pressure of 10-80Mpa, then carrying out pressure supplement of 10min and 40Mpa, ensuring that a formed working body of the grinding wheel has integral compactness, high strength, grinding resistance and good toughness, then carrying out pressure relief, and carrying out gradient temperature reduction (the temperature reduction rate is set to be 5-8 ℃/min) to be lower than 100 ℃, and then unloading the mold to complete hot-die pressing molding and obtain a semi-finished product;
and then carrying out secondary curing on the semi-finished product in a high-temperature oven: baking at 200 deg.C for 70min, baking at 220 deg.C for 50min, baking at 260 deg.C for 500min, baking at 220 deg.C for 80min, and baking at 120 deg.C for 60min, wherein the temperature rise and temperature decrease are respectively at 5-8 deg.C/min, and cooling to obtain PAI resin-based grinding wheel.
The sheet-layered tufted 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
A PAI resin-based grinding wheel of this example was produced in the same manner as in example 1, except that the PAI resin used in example 1 was the PAI resin obtained in CN202011184708.9 (i.e., the water-to-material ratio was 10: 1).
Comparative example 2
A PAI resin-based grinding wheel of this example was produced in the same manner as in example 1, except that PAI (available from Suwei group) synthesized in an organic solvent was used.
Comparative example 3
A PAI resin-based grinding wheel of this example was produced in the same manner as in example 1, except that the materials were subjected to conventional high-speed mixing (without vacuum negative pressure and steel balls) at a speed of 3000rpm, and other conditions such as heating temperature and mixing time during the high-speed mixing were the same as in example 1.
Comparative example 4
A PAI resin-based grinding wheel of this example was produced in the same manner as in example 1 except that the evacuation to a negative pressure was not conducted during the preliminary mixing.
Comparative example 5
A PAI resin-based grinding wheel of this example was produced in the same manner as in example 1, except that no steel balls were added during the pre-stress mixing process.
Comparative example 6
A PAI resin-based grinding wheel of this example was produced in the same manner as in example 1 except that no acidic substance was added and no secondary curing was conducted.
Example 3
PAI obtained in examples 1 to 2 and comparative examples 1 to 5Application of resin-based grinding wheel in processing of 99% aluminum oxide (Al)2O3) Ceramic tubes (the hardness of the tube of this material is close to that of diamond) with a length of 100mm and an internal diameter of 89mm, which need to be machined to an internal diameter of 95 mm.
The size of the grinding wheel is as follows: the outer diameter is 80mm, the thickness is 20mm, and the thickness of a grinding wheel working layer (a working layer containing PAI resin base and abrasive) is 10 mm.
The grinding wheel is used for grinding 99 percent of aluminum oxide (Al)2O3) The grinding time of the ceramic tube, the abrasion of the outer ring of the grinding wheel, the working life of the material (99% alumina ceramic) and other properties were tested, and the results are shown in table 1.
TABLE 1 grinding wheel Properties obtained in examples 1 to 2 and comparative examples 1 to 5
(Note: in the table, the conventional diamond metal sintered wheel is referred to, and the surface thereof is provided with a diamond sintered layer, the thickness of the diamond sintered layer is 0.6mm, and the object diagram is shown in FIG. 1A)
As can be seen from Table 1, the PAI resin-based grinding wheel is obtained by adopting lamellar clustered PAI as a binder, adding grinding materials and acidity, carrying out pre-stress mixing, carrying out hot compression molding, and carrying out secondary curing.
The grinding wheel of comparative example 1 uses PAI prepared by using a binder with a water-to-material ratio of 10:1, the grinding wheel of comparative example 2 uses PAI synthesized by using a conventional organic solvent, the microstructures of the PAI and the PAI do not have a lamellar cluster structure, the grinding time of a workpiece by using the grinding wheel prepared by using the PAI and the PAI is longer than that of the workpiece by using the PAI and the PAI, the abrasion loss of an outer ring of the grinding wheel is slightly larger than that of the PAI, and the service life of the PAI is shorter.
The data of comparative examples 3 to 5 illustrate that the optimized pre-stress mixing means is not completely adopted, so that the abrasive cannot be uniformly dispersed among the layers of the PAI in the lamellar cluster, the technical effect of uniform monodispersed coating state which can be achieved by the present invention cannot be achieved, and thus the abrasive is non-uniformly dispersed, the resin is melted by high temperature and the bonding degree of the abrasive is affected, and the protective layer with toughness cannot be formed on the periphery, which causes the sand removal of the grinding wheel during grinding, and the sand removal is the simple phase grinding of the PAI resin and the ceramic, so that the problem that the whole grinding wheel is not wear-resistant is caused. The grinding wheel of comparative example 6 could not be secondarily cured without adding an acidic substance, and the grinding wheel not secondarily cured had poor heat resistance.
The invention adopts the prestress mixing means to greatly prolong the service life of the grinding wheel, and the grinding material can be more uniformly dispersed in the resin matrix by the prestress mixing means, thereby realizing the monodispersion effect of particles.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (10)
1. A PAI resin-based grinding wheel production method, characterized by comprising the steps of:
(1) preparing PAI resin, abrasive and acidic organic matter; performing coupling treatment on the abrasive;
(2) pre-stress mixing materials including the PAI resin, the coupled abrasive and the acidic organic matter, and heating while vacuumizing in the process of pre-stress mixing to generate negative pressure to obtain uniformly mixed materials;
(3) and (3) fixing the supporting structural part in a grinding wheel die, adding the material uniformly mixed in the step (2), performing integral hot-die pressing and forming, and performing secondary curing at 180-380 ℃ after forming to obtain the PAI resin-based grinding wheel.
2. A PAI resin-based grinding wheel as set forth in claim 1, wherein said PAI resin is in a range of 30 to 55 wt%, said abrasive is in a range of 44.7 to 65 wt%, and said acidic organic substance is in a range of 0.3 to 5 wt%.
3. The method for producing a PAI resin-based grinding wheel according to claim 1 or 2, wherein the PAI resin microstructure is a lamellar cluster structure.
4. A PAI resin-based grinding wheel as set forth in claim 3, wherein the PAI resin is obtained by a method of synthesizing a polyamide-imide resin in an aqueous phase, and the PAI resin having a microstructure of lamellar clusters is obtained by controlling the ratio of the total mass of the raw material acid and the diamine-based compound to the weight of the added water to 1 (21-100) in the production process.
5. A PAI resin-based grinding wheel manufacturing method as set forth in claim 3, wherein said acidic organic substance is one or more of isocyanates, sulfonyl chlorides, aldehydes, epoxies, and acid anhydrides.
6. A PAI resin-based grinding wheel manufacturing method as set forth in claim 3, wherein the abrasive material comprises diamond and diamond grains, and the mass ratio of the diamond to the diamond grains is (6-10): (1-3); the grain size of the diamond is 50-250 meshes, and the grain size of the carborundum is 80-300 meshes; the carborundum is silicon carbide or a mixture of silicon carbide and boron nitride; the grinding 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 consumption of the metal powder accounts for 1-20 wt% of the PAI resin-based grinding wheel.
7. A PAI resin-based grinding wheel preparation method as claimed in claim 3, wherein the pre-stress mixing process is carried out by mixing steel balls with various diameters with the material, the diameter range of the steel balls is 10-50mm, the mass ratio of the steel balls to the material is (1-3):1, the pre-stress mixing process is carried out under vacuum degree of-0.05-0.09 Mpa, the heating temperature is 100-250 ℃, the mixing speed is 500-3000rpm, and the mixing time is 0.5-3 h.
8. A PAI resin-based grinding wheel as defined in claim 3 wherein the coupling treatment is carried out by dry or wet surface modification of the abrasive with a coupling agent treatment solution prepared by dissolving a coupling agent in water or alcohol to a mass concentration of 0.5-5 wt.%, said coupling agent being a silane-based coupling agent resistant to temperatures of 300 ℃ or higher.
9. A PAI resin-based grinding wheel manufacturing method as set forth in claim 3, wherein the temperature of the hot press molding is 200-380 ℃, the pressure is 20-100MPa, and the time is 50-150 min;
the secondary curing process comprises the following specific steps: baking at 200 ℃ for 30-90min at 100-;
the specific processes of the hot die pressing molding and the secondary curing are gradient temperature rise and gradient temperature reduction processes, and the temperature rise rate and the temperature reduction rate are 1-20 ℃/min;
the part of the support structure part, which is in contact with the material, is subjected to surface roughening treatment and then coupling treatment.
10. A PAI resin-based grinding wheel produced by the production method according to any one of claims 1 to 9.
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| CN111347354A (en) * | 2020-04-14 | 2020-06-30 | 郑州磨料磨具磨削研究所有限公司 | Grinding wheel for thinning silicon carbide crystal, preparation method and application thereof |
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| GB1188678A (en) * | 1966-11-02 | 1970-04-22 | Du Pont | Peripheral Abrasive Wheels with Composite Rims |
| CN1942284A (en) * | 2004-04-14 | 2007-04-04 | 3M创新有限公司 | Abrasive articles, compositions, and methods of making the same |
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| CN114571377B (en) | 2023-07-28 |
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