Composite fiber elastic polishing grinding wheel and preparation method thereof

Abstract

The present invention relates to a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel, comprising a grinding wheel abrasive layer and a grinding wheel base. The grinding wheel abrasive layer comprises polyvinyl alcohol fibers and Al2O3 abrasives tightly embedded in the outer surface and inner pores of the polyvinyl alcohol fibers. The grinding wheel abrasive layer is prepared by the steps of spinning solution preparation, wet spinning, heat stretching, acetalization, grinding wheel molding material preparation, hot pressing, grinding wheel abrasive layer curing, and bonding. The abrasive layer in the grinding wheel of the present invention is composed of polyvinyl alcohol / Al2O3 composite fibers that are randomly distributed and staggered, and has the characteristics of good elasticity and strong mechanical properties. The abrasive layer also contains a large number of voids, provides a large chip removal space, and has excellent heat dissipation performance, thereby preventing scratches on the workpiece during the polishing process.

Description

Technical Field

[0001] The invention belongs to the technical field of manufacturing finishing polishing abrasive tools in mechanical processing, and specifically relates to a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel and a preparation method thereof; the composite fiber elastic polishing grinding wheel has the characteristics of strong abrasive holding force, good elasticity, good water resistance and excellent heat dissipation performance. Background Art

[0002] Polishing technology is an emerging surface treatment method that uses the mechanical and chemical action of small-grain abrasives to remove trace amounts of surface material, achieving nanometer-level machining precision and excellent surface roughness. Currently, the abrasive tools commonly used for fine-grain abrasive grinding wheels with a certain hardness are fine-grain abrasive wheels. However, these fine-grain abrasive wheels have several drawbacks, including: the abrasive easily falls off the wheel surface; clogging and sticking to the wheel surface require resharpening; the abrasive particles easily break or break upon impact; linear scratches and burns easily form on the workpiece surface; high wheel wear and high cost; and the use of toxic and hazardous grinding fluids, which pose health risks to operators and pollute the environment. Clearly, existing abrasives and grinding tools cannot meet the requirements of ultra-precision machining, making the research and development of new abrasive tools incorporating new materials and forms urgent and necessary.

[0003] To overcome the aforementioned problems with traditional grinding wheels, scholars at home and abroad have conducted extensive research on the design and preparation of grinding wheels. The development of fiber grinding wheels is one such effective exploration and innovation. Fiber grinding wheels are wear-resistant, have a large aspect ratio, and possess a relatively large bonding area and strength with the grinding wheel bond, making them difficult to fall off the grinding wheel's grinding surface. Replacing traditional abrasives with these wheels to create new grinding tools has considerable practical value. Among them, polyvinyl alcohol (PVA) fiber is a type of fiber with excellent performance, characterized by good elasticity and toughness, as well as excellent wear resistance, weather resistance, and good adhesion to the substrate interface. Furthermore, Al2O3 abrasives, as wear-resistant materials with excellent comprehensive performance, have good dispersibility and offer unique advantages in the field of workpiece finishing and polishing. Therefore, the grinding wheel of the present invention uses PVA fiber as a carrier to fix and support the Al2O3 abrasive, creating a PVA / Al2O3 composite fiber. This is then subjected to grinding wheel shaping to ultimately produce a PVA / Al2O3 composite fiber elastic polishing grinding wheel, addressing the aforementioned issues with traditional fine-abrasive grinding wheels and enabling ultra-precision polishing of workpieces. Summary of the Invention

[0004] This invention addresses the technical problems of existing fine-abrasive grinding wheels during polishing, such as easy abrasive shedding, limited chip removal space, clogged work surfaces, and high grinding temperatures. The invention provides a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel with high abrasive holding power, excellent elasticity, and superior heat dissipation. This wheel eliminates chip sticking during workpiece processing, resulting in a uniform, burn-free surface finish and a surface roughness (Ra) of 0.05-0.25μm.

[0005] The second object of the present invention is to provide a method for preparing the above-mentioned polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel comprises an abrasive layer and a grinding wheel base. The abrasive layer comprises polyvinyl alcohol fibers and Al2O3 abrasive tightly embedded in the outer surface and inner pores of the polyvinyl alcohol fibers. The abrasive layer is used for polishing workpieces. The grinding wheel base is connected to a machine tool and bonded to the abrasive layer. Its lower surface is connected to the machine tool, and its upper surface is bonded to the abrasive layer via a mixed adhesive.

[0008] A method for preparing the above-mentioned polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel comprises the following steps:

[0009] S1. Preparation of spinning solution: adding an Al2O3 suspension to a polyvinyl alcohol aqueous solution, stirring and mixing at room temperature, and then standing at normal pressure for degassing to obtain a polyvinyl alcohol / Al2O3 spinning solution. Specifically, a certain amount of polyvinyl alcohol and deionized water are mixed, and the mixture is stirred continuously for a certain period of time using a stirrer in a water bath at a certain temperature to obtain a polyvinyl alcohol aqueous solution; after the mixture is cooled to room temperature, a certain amount of Al2O3 suspension is added, and the mixture is stirred at room temperature for a certain period of time, and the dispersion is stood at normal pressure for degassing for a certain period of time to obtain a polyvinyl alcohol / Al2O3 spinning solution.

[0010] S2, wet spinning: The polyvinyl alcohol / Al2O3 spinning solution prepared in S1 is delivered to the spinning assembly by a metering pump, sprayed into the coagulation bath through a spinneret of a certain aperture, and allowed to stay for a certain period of time to solidify and form to obtain the primary polyvinyl alcohol / Al2O3 composite fiber;

[0011] S3, heat stretching treatment: drying the nascent polyvinyl alcohol / Al2O3 composite fiber obtained in S2, and then heat stretching the composite fiber for a certain time under a certain temperature and a certain stretching ratio to obtain a semi-finished polyvinyl alcohol / Al2O3 composite fiber;

[0012] S4, acetalization treatment: placing the semi-finished polyvinyl alcohol / Al2O3 composite fiber obtained in S3 into a butyraldehyde aqueous solution of a certain concentration, stirring continuously for a certain period of time in a water bath environment at a certain temperature, and then mechanically crimping, cutting, washing and drying to obtain a polyvinyl alcohol / Al2O3 composite fiber of a certain length;

[0013] S5. Preparation of grinding wheel molding material: Resin powder and the polyvinyl alcohol / Al2O3 composite fiber prepared in S4 are mixed in proportion and poured into a vibration mixer and vibrated continuously for a period of time (the vibration mixer is used to place the fiber sample and resin powder in the machine and repeatedly vibrate to ensure that the surface of the fiber sample is evenly coated with a layer of resin powder. Ordinary commercial products can be directly purchased. Since their structure is not the innovation of this application, they will not be described in detail). Polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel molding material is prepared;

[0014] S6, hot pressing molding: putting the grinding wheel molding material obtained in S5 into the mold cavity, and pressing and molding it by a press under certain temperature and pressure conditions to obtain a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel abrasive layer blank;

[0015] S7, solidifying the grinding wheel abrasive layer: placing the grinding wheel abrasive layer blank obtained in S6 in a blast oven, drying it at a certain temperature for a certain period of time, and then cooling it to room temperature to obtain a grinding wheel abrasive layer;

[0016] S8, bonding: bonding the grinding wheel abrasive layer prepared in S7 to the grinding wheel base through mixed glue to obtain the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel.

[0017] Furthermore, in step S1, the polyvinyl alcohol has a degree of polymerization of 1000-3000 and a degree of alcoholysis of 86.0-98.0% (mol / mol). Specifically, one or more of polyvinyl alcohols 1588, 1788, 2088, 2488, 2299, and 2499 can be used. The mass percentage of the polyvinyl alcohol aqueous solution ranges from 15-25% by weight; the amount of Al2O3 added is 30-70% of the mass of the polyvinyl alcohol, and the Al2O3 particle size ranges from 500# to 1000#. During the preparation of the polyvinyl alcohol aqueous solution, the water bath temperature ranges from 50-95°C, the stirrer speed is 400-600 rpm, and the stirring time is 90-120 minutes. The mass percentage of the polyvinyl alcohol aqueous solution ranges from 15-25% by weight. Subsequently, a certain amount of Al2O3 suspension with a solid phase mass percentage of 40-60% is added, and the mixture is stirred at room temperature for 20-50 minutes. The degassing time at normal pressure is preferably 5-12 hours.

[0018] Furthermore, in step S2, the spinneret aperture ranges from 0.05 to 0.35 mm; the coagulation bath is a supersaturated sodium sulfate aqueous solution; and the residence time is 20 to 30 seconds.

[0019] Furthermore, in step S3, the heat stretching temperature is 150-300°C; the heat stretching ratio is 5-10 times; and the heat stretching time is 10-20 minutes.

[0020] Furthermore, in step S4, the concentration of the butyraldehyde aqueous solution is in the range of 50-80 g / L; the water bath temperature is in the range of 60-80° C., and the stirring time is 30-60 min; and the length of the prepared polyvinyl alcohol / Al 2 O 3 composite fiber is in the range of 30-70 mm.

[0021] Furthermore, in step S5, the resin powder accounts for 10-30% by mass, and the polyvinyl alcohol / Al2O3 composite fiber produced in S4 accounts for 70-90% by mass, i.e., the sum of the mass percentages of the resin powder and the polyvinyl alcohol / Al2O3 composite fiber is 100%. The resin powder is phenolic resin powder with a particle size range of 30-60 μm. The vibration mixer is vibrated for 10-30 minutes.

[0022] Furthermore, in step S6, during the pressing process of the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel molding material, the pressing temperature is 170-190°C, the pressing pressure is 1-4MPa, and the holding time is 30-50min.

[0023] Furthermore, in step S7, the temperature of the blast oven is 100-120° C., and the drying time is 8-12 hours.

[0024] Furthermore, in step S8, the mixed glue is formed by uniformly mixing epoxy resin glue and metal glue in a ratio of 3:1.

[0025] The present invention also provides a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel prepared by the preparation method.

[0026] The abrasive layer in the polyvinyl alcohol / Al2O3 composite fiber elastic polishing wheel of the present invention is composed of polyvinyl alcohol / Al2O3 composite fibers randomly distributed and staggered, and has the characteristics of good elasticity and strong mechanical properties; at the same time, the abrasive layer contains a large number of gaps, has a large chip removal space, and has excellent heat dissipation performance, which avoids scratches on the workpiece during the polishing process. The Al2O3 abrasive is tightly embedded in the outer surface and inner hole of the polyvinyl alcohol fiber, has a strong abrasive holding force, is not easy to fall off, and can effectively participate in the polishing of the workpiece. When the polyvinyl alcohol / Al2O3 composite fiber elastic polishing wheel prepared by the present invention is used to process a workpiece, the surface roughness of the processed workpiece is low, the surface quality is high, and the sub-surface damage is low.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel of the present invention is light and elastic, has good flexibility, and can polish workpieces stably and continuously for a long time;

[0029] (2) In the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel of the present invention, the Al2O3 abrasive is tightly embedded in the outer surface and inner hole of the polyvinyl alcohol fiber, and the abrasive has a strong holding force and is not easy to fall off;

[0030] (3) The polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel of the present invention can effectively participate in grinding, has a high abrasive utilization rate, can evenly remove workpiece material, and has a high removal rate; when using the grinding wheel to process workpieces, the grinding wheel does not have chip sticking phenomenon, the surface texture of the processed workpiece is uniform and free of burns, and the surface roughness (Ra) of the workpiece is 0.05-0.25μm;

[0031] (4) The polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel of the present invention has uniform pores inside the composite fiber with a pore size at the micron level. The micropores can quickly remove grinding debris, have excellent heat dissipation performance, and are not prone to clogging;

[0032] (5) The polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel of the present invention has simple processing operation, high processing efficiency, good processing effect, low cost of raw materials and manufacturing equipment used, simple and stable product preparation process, and is easy to mass produce and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0034] Figure 1 The specific process flow diagram of the present invention is as follows;

[0035] Figure 2 This is a SEM schematic diagram of the surface of the polyvinyl alcohol / Al2O3 composite fiber prepared in step S4 of Example 1 of the present invention;

[0036] Figure 3 This is a schematic SEM diagram of the cross section of the polyvinyl alcohol / Al2O3 composite fiber prepared in step S4 of Example 1 of the present invention;

[0037] Figure 4 For Figure 3 Schematic diagram of backscattering at the same cross-section of polyvinyl alcohol / Al2O3 composite fiber;

[0038] Figure 5This is a SEM schematic diagram of the cross section of the abrasive layer of the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel prepared in Example 1 of the present invention;

[0039] Figure 6 This is a macroscopic schematic diagram of the polyvinyl alcohol / Al2O3 composite fiber elastic polishing wheel prepared in Example 2 of the present invention after processing a 304 stainless steel part with a size of 25*25*5;

[0040] Figure 7 This is a macroscopic schematic diagram of the traditional resin-bonded corundum grinding wheel prepared in Comparative Example 1 after processing a 304 stainless steel part with a size of 25*25*5. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the following examples, unless otherwise specified, all raw materials used are commercially available products in the art. The mixed adhesive is prepared by uniformly mixing epoxy resin adhesive and metal adhesive in a mass ratio of 3:1. Room temperature refers to 25±5°C.

[0043] Example 1

[0044] A 6A2-125*25*31.75*10*8 polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel with a grit size of 1000# is prepared, which includes a grinding wheel abrasive layer and a grinding wheel base. The grinding wheel abrasive layer contains polyvinyl alcohol fibers and Al2O3 abrasive with a grit size of 1000# tightly embedded in the outer surface and inner pores of the polyvinyl alcohol fibers. The preparation method of the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel includes the following steps (flow chart as shown in FIG. Figure 1 shown):

[0045] S1. Preparation of spinning solution: 100 g of polyvinyl alcohol (model 1788) with a degree of polymerization of 1700 and a degree of alcoholysis of 88±2% (mol / mol) and 500 g of deionized water were added to a reactor, and the mixture was stirred and dissolved at a speed of 500 r / min in a 90°C water bath for 90 min to obtain a polyvinyl alcohol aqueous solution with a mass percentage of 16.67 wt%; after the polyvinyl alcohol aqueous solution was cooled to room temperature, 100 mL of an Al2O3 suspension with a solid mass percentage of 60% and a particle size of 1000# was added thereto, and the mixture was stirred at room temperature for 30 min. The dispersion was then allowed to stand at normal pressure for degassing for 6 h to prepare a polyvinyl alcohol / Al2O3 spinning solution;

[0046] S2, wet spinning: The spinning solution prepared in S1 was delivered to the spinning assembly by a metering pump, and the spinning solution was ejected through a spinneret with a pore size of 0.20 mm. The spinning solution was placed in a coagulation bath of a supersaturated sodium sulfate aqueous solution for 20 seconds, and solidified to obtain the primary polyvinyl alcohol / Al2O3 composite fiber;

[0047] S3, heat stretching treatment: drying the nascent composite fiber obtained in S2, then setting the heat stretching temperature to 180°C, the heat stretching ratio to 5 times, and biaxially stretching the composite fiber for 10 minutes to obtain a semi-finished polyvinyl alcohol / Al2O3 composite fiber;

[0048] S4, butyral treatment: Prepare 500 mL of a 50 g / L butyraldehyde aqueous solution; then place the semi-finished composite fiber obtained in S3 into the butyraldehyde aqueous solution and continuously stir in a 60°C water bath for 30 minutes. Then, mechanically crimp, cut, wash, and dry to obtain a polyvinyl alcohol / Al2O3 composite fiber with a length of 30 mm and an outer diameter of approximately 0.2 mm.

[0049] S5, preparation of grinding wheel molding material: 10g of phenolic resin powder with a particle size range of 30-60μm was mixed with 50g of the composite fiber prepared in S4 and poured into a vibration mixer and vibrated continuously for 15min to prepare a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel molding material;

[0050] S6, hot pressing: placing the grinding wheel molding material obtained in S5 into a mold cavity, and maintaining the pressure for 30 minutes at a temperature of 180° C. and a pressure of 2.0 MPa using a press to obtain a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel abrasive layer blank;

[0051] S7, solidifying the grinding wheel abrasive layer: placing the grinding wheel abrasive layer blank obtained in S6 in a 100° C. forced air oven for 10 hours, and then cooling to room temperature to obtain the grinding wheel abrasive layer;

[0052] S8, bonding: bonding the grinding wheel abrasive layer prepared in S7 to the polishing grinding wheel base through mixed glue to obtain the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel.

[0053] Figure 2 The SEM diagram of the surface of the polyvinyl alcohol / Al2O3 composite fiber prepared in step S4 of this embodiment is given. Figure 2 The figure shows the main body of polyvinyl alcohol fiber and the Al2O3 abrasive tightly embedded in the outer surface of the polyvinyl alcohol fiber. The outer diameter of the polyvinyl alcohol fiber is 0.21mm, and the particle size of the Al2O3 abrasive is 10-15μm.

[0054] Figure 3 The following is a SEM diagram of the cross section of the polyvinyl alcohol / Al2O3 composite fiber prepared in step S4 of this embodiment. Figure 3 It can be seen that the polyvinyl alcohol / Al2O3 composite fiber is porous inside, and the pores are evenly distributed, with a pore size range of 5-20μm.

[0055] Figure 4 For Figure 3 Schematic diagram of backscattering at the same cross-section of polyvinyl alcohol / Al2O3 composite fiber. Figure 4 It can be seen that the bright particles indicated by the arrows are Al2O3 abrasives, and the Al2O3 abrasives are tightly embedded in the inner pores of the polyvinyl alcohol fiber.

[0056] Figure 5 The following is a SEM diagram of the cross section of the abrasive layer of the polyvinyl alcohol / Al2O3 composite fiber elastic polishing wheel prepared in this example. Figure 5 It can be seen that the polyvinyl alcohol / Al2O3 composite fibers are connected by resin powder, and there are a large number of gaps between each composite fiber, with a large chip removal space, which provides a structural basis for the grinding wheel to grind efficiently, dissipate heat quickly, and avoid scratches on the workpiece during polishing.

[0057] The grinding wheel prepared in this example was used to polish a 304 stainless steel part with a size of 25*25*5 on an X61D9B2M-T grinding machine produced by Suzhou Heruit Electronic Special Equipment Technology Co., Ltd. The processing parameters and results are shown in Table 1.

[0058] Table 1 Processing parameters and processing effects of polishing 304 stainless steel parts using the grinding wheel prepared in Example 1

[0059]

[0060] Example 2

[0061] A 6A2-200*25*31.75*30*10 polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel with a grit size of 600# was prepared. The wheel comprises an abrasive layer and a grinding wheel base. The abrasive layer comprises polyvinyl alcohol fibers and a 600# Al2O3 abrasive tightly embedded in the outer surface and inner pores of the polyvinyl alcohol fibers. The method for preparing the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel comprises the following steps:

[0062] S1. Preparation of spinning solution: 500 g of polyvinyl alcohol (model 2488) with a degree of polymerization of 2400 and a degree of alcoholysis of 88±2% (mol / mol) and 2000 g of deionized water were added to a reactor, and dissolved and stirred at a speed of 600 r / min in a 95°C water bath for 120 min to obtain a polyvinyl alcohol aqueous solution with a mass percentage of 20.0 wt%; after the polyvinyl alcohol aqueous solution was cooled to room temperature, 500 mL of an Al2O3 suspension with a particle size of 600# and a solid phase mass percentage of 50% was added thereto, and stirring was continued at room temperature for 30 min. The dispersion was then allowed to stand at normal pressure for 10 h to deaerate, thereby preparing a polyvinyl alcohol / Al2O3 spinning solution;

[0063] S2, wet spinning: The spinning solution prepared in S1 was delivered to the spinning assembly by a metering pump, and the spinning solution was ejected through a spinneret with a pore size of 0.30 mm. The spinning solution was placed in a coagulation bath of a supersaturated sodium sulfate aqueous solution for 30 seconds, and solidified to obtain the primary polyvinyl alcohol / Al2O3 composite fiber;

[0064] S3, heat stretching treatment: drying the nascent composite fiber obtained in S2, then setting the stretching temperature to 220°C, the heat stretching ratio to 6 times, and biaxially stretching the composite fiber for 15 minutes to obtain a semi-finished polyvinyl alcohol / Al2O3 composite fiber;

[0065] S4, butyral treatment: Prepare 2000 mL of an 80 g / L butyraldehyde aqueous solution; then place the semi-finished composite fiber obtained in S3 into the butyraldehyde aqueous solution and continuously stir in a 70°C water bath for 45 minutes. Then, mechanically crimp, cut, wash, and dry to obtain a polyvinyl alcohol / Al2O3 composite fiber with a length of 50 mm and an outer diameter of approximately 0.3 mm.

[0066] S5, preparation of grinding wheel molding material: 60g of phenolic resin powder with a particle size range of 30-60μm was mixed with 350g of the composite fiber prepared in S4 and poured into a vibration mixer and vibrated continuously for 30min to prepare a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel molding material;

[0067] S6, hot pressing: placing the grinding wheel molding material obtained in S5 into a mold cavity, and maintaining the pressure for 45 minutes at a temperature of 180° C. and a pressure of 3.0 MPa using a press to obtain a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel abrasive layer blank;

[0068] S7, solidifying the grinding wheel abrasive layer: placing the grinding wheel abrasive layer blank obtained in S6 in a 120° C. forced air oven for 12 hours, and then cooling to room temperature to obtain the grinding wheel abrasive layer;

[0069] S8, bonding: bonding the grinding wheel abrasive layer prepared in S7 to the polishing grinding wheel base through mixed glue to obtain the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel.

[0070] The grinding wheel of this embodiment was used to polish a 304 stainless steel part with a size of 25*25*5 on an X61 D9B2M-T grinding machine produced by Suzhou Heruit Electronic Special Equipment Technology Co., Ltd. The processing parameters and results are shown in Table 2.

[0071] Table 2 Processing parameters and processing effects of polishing 304 stainless steel parts using the grinding wheel prepared in Example 2

[0072]

[0073] Figure 6 This is a macroscopic diagram of a 25*25*5 304 stainless steel part machined using the grinding wheel of this embodiment. As can be seen from the figure, the workpiece has uniform lines after machining, and there are no defects such as burns and scratches on the surface.

[0074] Comparative Example 1

[0075] The difference between this comparative example and the formulation of Example 1 is that the abrasive layer of the grinding wheel is replaced with traditional ordinary corundum abrasive (i.e., Al2O3 abrasive).

[0076] A traditional resin bond grinding wheel (Comparative Example 1) with a specification of 6A2-125*25*31.75*10*8 was made using corundum abrasive with a particle size of 1000#. The mass percentage and type of each raw material are shown in Table 3.

[0077] Table 3 Mass percentage and type of each raw material

[0078]

[0079] The preparation method of the above-mentioned conventional resin bonded grinding wheel (Comparative Example 1) specifically comprises the following steps:

[0080] S1. Mixing: Weigh the materials according to the above formula ratio, with a total weight of 115g, pour them into a stainless steel basin and stir repeatedly, and pass them through an 80# sieve 3 times to obtain a uniformly mixed molding material;

[0081] S2: Hot pressing: After the molding material prepared in S1 is combined with the cast aluminum substrate of corresponding size and the mold, the semi-finished grinding wheel is obtained by pressing at a temperature of 180°C and a pressure of 2.0 MPa for 30 minutes;

[0082] S3: Post-curing: The semi-finished grinding wheel blank obtained in S2 is placed in a 100°C forced air oven for 10 hours, and then cooled to room temperature to obtain a finished grinding wheel.

[0083] Subsequently, the conventional resin-bonded corundum grinding wheel prepared in Comparative Example 1 was used to polish a 304 stainless steel part having a size of 25*25*5 on an X61 D9B2M-T grinding machine of Suzhou Heruit Electronic Special Equipment Technology Co., Ltd. using the same processing parameters as in Example 1. The properties of the grinding wheel itself and the processing effect are shown in Table 4.

[0084] Table 4 Polishing effect of 304 stainless steel parts using Example 1 and Comparative Example 1

[0085]

[0086] Figure 7 This is a macroscopic diagram of a 304 stainless steel part with a size of 25*25*5 processed using the grinding wheel of Comparative Example 1. Figure 7 It can be seen from the figure that after processing, the workpiece has obvious burn defects on the surface, and the box in the figure is the burn area of ​​the workpiece. At the same time, it can be seen from Table 4 that:

[0087] 1) The hardness of the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel in Example 1 of the present invention is significantly lower than that of the traditional resin-bonded corundum grinding wheel described in Comparative Example 1. This is because the grinding wheel in Example 1, prepared with the polyvinyl alcohol / Al2O3 composite fiber as the abrasive layer, is primarily composed of polyvinyl alcohol fibers. The inherent elasticity and strong mechanical properties of polyvinyl alcohol impart significant elasticity and strength to the polyvinyl alcohol / Al2O3 composite fiber grinding wheel.

[0088] 2) The polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel of Example 1 of the present invention did not exhibit chip sticking during processing, and the workpiece had uniform lines and no burns after processing. The traditional resin-bonded corundum grinding wheel described in Comparative Example 1 exhibited chip sticking during processing, and obvious burn defects appeared on the workpiece after processing. This is because the abrasive layer in the grinding wheel of the present invention is composed of polyvinyl alcohol / Al2O3 composite fibers that are randomly distributed and staggered, and contain a large amount of space inside. At the same time, the polyvinyl alcohol / Al2O3 composite fibers are porous inside, further increasing the chip holding and chip removal space of the grinding wheel. As a result, under the same processing conditions, the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel of the present invention has higher processing effect and efficiency when the grinding wheel has the same size.

[0089] 3) The surface roughness of the workpiece processed using the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel made from the polyvinyl alcohol / Al2O3 composite fiber of Example 1 of the present invention (0.05-0.15 μm) is significantly better than the surface roughness of the workpiece processed using the traditional resin-bonded grinding wheel made from conventional corundum abrasive (0.30-0.50 μm). This is because when the grinding wheel of the present invention is subjected to external force during the polishing process, it undergoes a certain degree of elastic deformation due to its inherent elasticity, which can buffer the grinding force, support the grinding and polishing process, and thus improve the surface finish of the workpiece.

[0090] In summary, the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel prepared by the present invention can be used to grind workpieces, and the workpiece surface can meet the use requirements. At the same time, due to the structural characteristics of the random distribution and staggered structure of the polyvinyl alcohol / Al2O3 composite fibers and the Al2O3 abrasive tightly embedded in the outer surface and inner pores of the polyvinyl alcohol fibers, the polishing grinding wheel has good elasticity, strong mechanical properties, excellent heat dissipation performance, strong abrasive holding force, and is not easy to fall off. It can be seen that the polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel prepared by the present invention has stable performance and long service life, and has high promotion value.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite fiber elastic polishing grinding wheel, characterized in that: The composite fiber elastic polishing grinding wheel comprises a grinding wheel abrasive layer and a grinding wheel base, wherein the grinding wheel abrasive layer comprises polyvinyl alcohol fiber and Al2O3 abrasive tightly embedded in the outer surface and inner hole of the polyvinyl alcohol fiber; The composite fiber elastic polishing grinding wheel is prepared by the following steps: S1. Preparation of spinning solution: Add Al2O3 suspension to polyvinyl alcohol aqueous solution, stir and mix at room temperature, and then stand at normal pressure for degassing to obtain polyvinyl alcohol / Al2O3 spinning solution; S2, wet spinning: the polyvinyl alcohol / Al2O3 spinning solution prepared in S1 is sprayed into the coagulation bath through the spinneret, and allowed to stand for a certain period of time to solidify and form to obtain the primary polyvinyl alcohol / Al2O3 composite fiber; S3, heat stretching treatment: drying the nascent polyvinyl alcohol / Al2O3 composite fiber obtained in S2, and then heat stretching the biaxially stretched composite fiber to obtain a semi-finished polyvinyl alcohol / Al2O3 composite fiber; S4, acetalization treatment: placing the semi-finished polyvinyl alcohol / Al2O3 composite fiber obtained in S3 into a butyraldehyde aqueous solution, continuously stirring in a water bath environment, and then mechanically crimping, cutting, washing and drying to obtain the polyvinyl alcohol / Al2O3 composite fiber; S5, preparation of grinding wheel molding material: mixing the resin powder with the polyvinyl alcohol / Al2O3 composite fiber prepared in S4 and pouring the mixture into a vibrating mixer and continuously vibrating the mixture to prepare a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel molding material; S6, hot pressing molding: putting the grinding wheel molding material obtained in S5 into the mold cavity for pressing and molding to obtain a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel abrasive layer blank; S7, solidifying the grinding wheel abrasive layer: placing the grinding wheel abrasive layer blank obtained in S6 in a blast oven to dry, and then cooling to room temperature to obtain a grinding wheel abrasive layer; bonding the obtained grinding wheel abrasive layer to a grinding wheel substrate to obtain a polyvinyl alcohol / Al2O3 composite fiber elastic polishing grinding wheel; In step S1, the degree of polymerization of polyvinyl alcohol is 1000-3000, the degree of alcoholysis is 86.0-98.0%, mol / mol; the mass percentage of the polyvinyl alcohol aqueous solution is in the range of 15-25wt%; the amount of Al2O3 added is 30-70% of the mass of the polyvinyl alcohol, and the particle size of Al2O3 is in the range of 500#-1000#; In step S2, the spinneret aperture is 0.05-0.35 mm; the coagulation bath is a supersaturated sodium sulfate aqueous solution; and the residence time is 20-30 s; In step S3, the heat stretching temperature is 300°C; the heat stretching ratio is 10 times; and the heat stretching time is 20 minutes. In step S4, the concentration of the butyraldehyde aqueous solution is 50-80 g / L; the water bath temperature is 60-80° C.; In step S5, the resin powder is 10-30% by mass, and the polyvinyl alcohol / Al2O3 composite fiber prepared in S4 is 70-90% by mass; the resin powder is phenolic resin powder with a particle size of 30-60 μm; In step S6, the pressing temperature is 170-190°C, the pressing pressure is 1-4 MPa, and the holding time is 30-50 min; In step S7, the temperature of the blast oven is 100-120°C and the drying time is 8-12 hours; When using this grinding wheel to process workpieces, there is no chip sticking phenomenon. The surface texture of the workpiece after processing is uniform and there is no burn. The surface roughness Ra of the workpiece is 0.05-0.25μm.

2. The composite fiber elastic polishing grinding wheel prepared by the preparation method according to claim 1.

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