Toughening method for ceramic bond grinding wheel

Abstract

The invention belongs to the technical field of grinding tools, and particularly relates to a toughening method for a ceramic bond grinding wheel. The toughening method of the ceramic bond grinding wheel comprises the following steps that the ceramic bond grinding wheel is subjected to dipping treatment in resin liquid, curing is carried out after dipping treatment is completed, the resin liquid comprises thermosetting resin with the mass fraction of 94-96%, the thermosetting resin is selected from one of epoxy resin and polyester resin, and the thermosetting resin is selected from one of epoxy resin and polyester resin. And the viscosity of the resin liquid is 200 to 500 mPa.s. The resin liquid enters a gap between the ceramic bond and the grinding material in the dipping process and forms a bridging effect, so that the toughness of the ceramic bond grinding wheel is remarkably enhanced, the use linear speed of the grinding wheel is increased, and the working efficiency of the grinding wheel is improved; and part of falling abrasives, abrasive dust and heat can be taken away, the possibility that the abrasive tool burns a workpiece is reduced, and the surface quality of the workpiece is higher.

Description

Technical Field

[0001] The invention relates to the technical field of grinding tools, and in particular to a toughening method for a ceramic bond grinding wheel. Background Art

[0002] Vitrified bond grinding wheels are mainly composed of three parts: vitrified bond, abrasive, and pores. They are suitable for cutting and grinding of various workpieces. Vitrified bond is generally composed of minerals such as clay, feldspar, quartz, boron glass, etc. as the main raw materials. Vitrified bond has high chemical stability and strong bonding ability with abrasive. These minerals have high melting points and generally require high firing temperatures. The ceramic abrasives prepared by this method are brittle, have low use speed, are prone to breakage during the grinding process, and may cause safety accidents in serious cases. In addition, the surface quality of the ground workpiece is poor. In recent years, with the rapid development of precision instruments and equipment, the requirements for the processing efficiency and surface quality of workpieces have become increasingly higher. Therefore, ceramic abrasives are difficult to meet the requirements of high-end equipment. However, the use of superhard abrasives such as diamond is difficult to trim, the surface quality of the ground workpiece is poor, and the price is expensive, making it difficult to popularize and apply in large quantities; the use of resin abrasives requires frequent trimming, which affects the grinding efficiency, and the service life is much different from that of ceramic abrasives. Compared with ceramic molds, superhard abrasives and resin abrasives have low cost performance and limited application range.

[0003] In recent years, most of the methods used are improvements in ceramic binders or abrasives, such as changing the proportion and formula of ceramic binders, or modifying abrasives to improve the bonding strength between binders and abrasives, thereby improving the toughness of the grinding wheel. For example, the Chinese invention patent application with application publication number CN116728302A, which was applied for and published on September 12, 2023, discloses a high-speed precision grinding ceramic bond grinding wheel and a preparation method thereof. By using microcrystalline glass with a hexagonal lamellar structure and a grain size of 1 to 2 μm instead of conventional ceramics as a binder for the grinding wheel, the strength and impact toughness of the grinding wheel can be greatly improved, and the speed and life of the grinding wheel can be increased; however, the grinding wheel still has the problem of low surface quality of the workpiece being processed, which reduces the grinding performance of the grinding wheel. Then, the abrasive is modified and high-performance chrome corundum PA and single crystal corundum or microcrystalline corundum are used as grinding materials. The abrasive surface is treated with ceramic composite film using Al-Si-B-Na series multi-component high-strength nano-ceramic sol-gel in-situ film-forming treatment technology containing sodium borate. The new film-forming treatment process improves the wrapping of the abrasive by the binder. The binder structure formed by the sol is fine and can reach the nanometer level, thereby refining and homogenizing the microstructure of the grinding wheel and avoiding scratches on the processed surface caused by coarse-grained binders in traditional methods.

[0004] Therefore, although the modification method of the ceramic binder alone can improve the strength and impact toughness of the grinding wheel, in actual applications, the grinding force of the abrasive tool will still be reduced, the surface quality of the workpiece will be reduced, and the grinding effect will be less than ideal. The abrasives and other materials need to be modified, which makes the grinding wheel preparation process very complicated. Summary of the invention

[0005] The invention provides a toughening method for a vitrified bond grinding wheel, which solves the problem that the prior art cannot simultaneously improve the toughness of the vitrified bond grinding wheel and the surface quality of a workpiece.

[0006] In order to solve the above technical problems, the technical solution of the toughening method of the vitrified bond grinding wheel of the present invention is:

[0007] A toughening method for a vitrified bond grinding wheel comprises the following steps: impregnating the vitrified bond grinding wheel in a resin liquid, and curing the mixture after the impregnation is completed, wherein the resin liquid comprises a thermosetting resin with a mass fraction of 94 to 96%, the thermosetting resin being selected from one of an epoxy resin and a polyester resin, and the viscosity of the resin liquid is 200 to 500 mPa·s.

[0008] The present invention is an improvement on the prior art, and provides a toughening method for a ceramic bond grinding wheel. The ceramic bond grinding wheel is impregnated with a thermosetting resin liquid and solidified. The thermosetting resin liquid enters the gap between the ceramic bond and the abrasive during the impregnation process. The resin liquid is cross-connected with the abrasive and the ceramic bond through solidification, and is solidified into one. The bridging effect is increased between the ceramic bond and the abrasive, and the toughness of the ceramic bond grinding wheel is significantly enhanced. The linear speed of the grinding wheel is increased, the working efficiency of the grinding wheel is improved, and the surface roughness of the ground workpiece is significantly reduced, and the surface quality of the workpiece is improved. In addition, when the ceramic bond grinding wheel is ground at high speed, the high temperature generated will melt the resin on the surface of the grinding wheel, and the molten resin will take away some of the detached abrasive, grinding chips and heat, reducing the possibility of the grinding tool burning the workpiece during high-speed grinding, so that the surface quality of the workpiece is higher.

[0009] The toughening method provided by the present invention does not require regulating the components and formula of the vitrified binder, modifying the vitrified binder or controlling the grinding wheel forming process, etc. It only requires impregnation treatment of the existing vitrified binder grinding wheel. The process is simple, easy to implement, and has a wide range of applications, and is suitable for large-scale industrial applications.

[0010] In order to further improve the impregnation effect, preferably, the resin liquid is composed of 94-96% by mass of thermosetting resin, 4-8% by mass of resin curing accelerator and 0.5-1% by mass of anhydrous ethanol.

[0011] In order to further fully impregnate the resin liquid, preferably, the impregnation treatment is performed at room temperature for 6 to 12 hours.

[0012] In order to further improve the bridging effect between the ceramic binder and the abrasive, preferably, the curing is carried out by keeping the temperature at 60-120° C. for 2-4 hours.

[0013] In order to further improve the uniformity of the resin liquid and control the viscosity of the resin liquid, preferably, the resin liquid is obtained by heating the thermosetting resin to 50-90° C., adding a resin curing accelerator and anhydrous ethanol, and keeping the temperature for 0.5-1 hour.

[0014] In order to further improve the grinding performance of the vitrified bond grinding wheel, preferably, the vitrified bond grinding wheel is obtained by mixing vitrified bond, abrasive and dextrin liquid or water glass, followed by pressing and sintering.

[0015] In order to further improve the workpiece quality during grinding with a grinding wheel, preferably, the mass ratio of the ceramic binder to the abrasive is (10-15):(85-90), and the amount of dextrin liquid or water glass added is 1.5-2.5% of the total mass of the ceramic binder and the abrasive.

[0016] In order to further improve the strength of the grinding wheel, preferably, the sintering temperature is 1000-1100° C., and the sintering time is 5-8 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the organizational structure of a ceramic bond grinding wheel after being treated by the toughening method of the present invention. DETAILED DESCRIPTION

[0018] The technical concept of the toughening method of the vitrified bond grinding wheel of the present invention is as follows:

[0019] Among the existing methods for toughening ceramic bond grinding wheels, one is to adjust the composition and formula of the ceramic bond, and the other is to modify the ceramic bond. Although it is possible to improve the bonding strength between the ceramic bond and the abrasive, and thus improve the toughness of the grinding wheel, it still cannot solve the problems of low workpiece surface quality, reduced grinding force, and poor grinding effect. It is also necessary to modify the abrasive, as well as cooperate with the molding process, sintering process and other strengthening technical means, which greatly increases the process complexity and cost.

[0020] The toughening method provided by the present invention is to perform an impregnation treatment on the vitrified bond grinding wheel with a thermosetting resin liquid and solidify it. The thermosetting resin liquid enters the gap between the vitrified bond and the abrasive during the impregnation process. The resin liquid, the abrasive and the vitrified bond are cross-connected and solidified into one, thereby increasing the bridging effect between the vitrified bond and the abrasive. The organizational structure diagram of the vitrified bond grinding wheel after toughening treatment is as shown in FIG. Figure 1As shown, the toughness of the ceramic bond grinding wheel is significantly enhanced, the linear speed of the grinding wheel is increased, the working efficiency of the grinding wheel is improved, the frequency of dressing is reduced, and the surface roughness of the ground workpiece can be significantly reduced, the surface quality of the workpiece is improved, and the service life of the grinding wheel is increased. In addition, when the ceramic bond grinding wheel is ground at high speed, the high temperature generated will melt the resin on the surface of the grinding wheel, and the molten resin will take away some of the detached abrasives, grinding chips and heat, reducing the possibility of the abrasive tool burning the workpiece during high-speed grinding, so that the surface quality of the workpiece is higher; the toughening method provided by the present invention only needs to be impregnated on the existing ceramic bond grinding wheel, the process is simple, easy to implement, suitable for ceramic bond grinding wheels of different shapes, and can be impregnated on different positions and different ranges of the grinding wheel, with a wide range of applications, suitable for large-scale industrial applications. It can be understood that ceramic bond grinding wheels composed of different components can adopt the toughening method of the present invention.

[0021] In a specific embodiment, the components of the ceramic binder are: 25-30% feldspar, 35-40% clay, 25-30% borosilicate glass, 1-5% lithium carbonate, and 5-10% nepheline powder; or 30-35% feldspar, 25-30% kaolin, 25-30% borosilicate glass, 0.5-1% lithium carbonate, 10-15% talc, and 1-5% dextrin powder.

[0022] In a specific embodiment, the abrasive in the vitrified bond grinding wheel is white corundum or silicon carbide.

[0023] The embodiments of the present invention are further described below in conjunction with specific examples. The raw materials and chemical reagents used in the following examples are all commercially available conventional products.

[0024] 1. Specific embodiment of the toughening method of the vitrified bond grinding wheel of the present invention

[0025] Example 1

[0026] The toughening method of the vitrified bond grinding wheel of this embodiment is as follows:

[0027] 1) Preparation of Vitrified Bond Grinding Wheel

[0028] A ceramic binder and silicon carbide F220 abrasive in a mass ratio of 12:88 and dextrin liquid accounting for 2.0% of the total mass of the ceramic binder and the abrasive are mixed and stirred for 15 minutes to obtain a ceramic bond grinding wheel molding material, wherein the components of the ceramic binder are: 26% feldspar, 37% clay, 27% borosilicate glass, 1% lithium carbonate, and 9% nepheline powder; the ceramic bond grinding wheel molding material is placed in a mold and pressed to obtain a ceramic bond grinding wheel blank; the ceramic bond grinding wheel blank is then placed in a high-temperature furnace for sintering at a sintering temperature of 1060°C and a sintering time of 6 hours to obtain a ceramic bond grinding wheel.

[0029] 2) Preparation of resin liquid

[0030] Pour 95% epoxy resin (brand: E42) into a container, slowly stir and heat to 70°C, then add 4.2% accelerator DMP-30, and finally add 0.8% anhydrous ethanol, keep warm for 40 minutes, and obtain resin liquid (viscosity 462mPa·s).

[0031] 3) Impregnation treatment

[0032] Put the ceramic bond grinding wheel of step 1) into the resin liquid prepared in step 2), soak it at room temperature for 6 hours, take it out and put it into an oven after soaking, keep it at 110℃ for 3 hours, and remove the resin on the upper and lower surfaces, inner hole and outer circle of the grinding wheel and the excess size reserve by grinding the grinding wheel through the processing equipment after the insulation is completed. The resin solution enters the pores of the ceramic bond grinding wheel through soaking and blocks the pores, but during the grinding process of the grinding wheel, the high temperature generated causes the resin on the surface of the grinding wheel to melt and regenerate pores. The regenerated pores can play the role of chip storage, chip removal and heat dissipation, and the molten resin takes away some of the detached abrasives, chips and heat, reducing the possibility of the abrasive tool burning the workpiece during high-speed grinding, so that the surface quality of the workpiece is higher.

[0033] Example 2

[0034] The toughening method of the vitrified bond grinding wheel of this embodiment is as follows:

[0035] 1) The preparation of the vitrified bond grinding wheel is the same as the preparation method of step 1) in Example 1.

[0036] 2) Preparation of resin liquid

[0037] Pour 94% unsaturated polyester resin (brand: 3301 bisphenol A polyester resin) into a container, slowly stir and heat to 75°C, then add 5.5% accelerator cobalt isooctanoate, and finally add 0.5% anhydrous ethanol, keep warm for 40 minutes, and obtain a resin liquid (viscosity 367mPa·s).

[0038] 3) Impregnation treatment

[0039] The ceramic bond grinding wheel of step 1) is placed in the resin liquid prepared in step 2) and soaked at room temperature for 6 hours. After the soaking is completed, it is taken out and placed in an oven and kept warm at 110°C for 3 hours. After surface and inner and outer circle processing, a grinding wheel that can be used in normal production is obtained.

[0040] Example 3

[0041] The toughening method of the vitrified bond grinding wheel of this embodiment is as follows:

[0042] 1) Preparation of Vitrified Bond Grinding Wheel

[0043] A ceramic binder and white corundum F320 abrasive in a mass ratio of 14:86, and 2.0% of water glass (concentration 30%) of the total mass of the ceramic binder and the abrasive are mixed, and stirred for 15 minutes to obtain a ceramic bond grinding wheel molding material, wherein the components of the ceramic binder are: 32% feldspar, 25% kaolin, 27% borosilicate glass, 0.5% lithium carbonate, 12.5% ​​talc, and 4% dextrin powder; the ceramic bond grinding wheel molding material is placed in a mold and pressed to obtain a ceramic bond grinding wheel blank; the ceramic bond grinding wheel blank is then placed in a high-temperature furnace for sintering, the sintering temperature is 1080°C, and the sintering time is 7 hours to obtain a ceramic bond grinding wheel.

[0044] 2) Preparation of resin liquid

[0045] Pour 94.5% of epoxy resin (brand: E-51) into a container, slowly stir and heat to 80°C, then add 4.5% of accelerator DMP-30, and finally add 1% of anhydrous ethanol, keep warm for 45 minutes, and obtain a resin liquid (viscosity is 226mPa·s).

[0046] 3) Impregnation treatment

[0047] The ceramic bond grinding wheel of step 1) is placed in the resin liquid prepared in step 2) and soaked at room temperature for 7 hours. After the soaking is completed, it is taken out and placed in an oven and kept at 95°C for 4 hours. After surface and inner and outer circle processing, a grinding wheel that can be used in normal production is obtained.

[0048] Example 4

[0049] The toughening method of the vitrified bond grinding wheel of this comparative example is as follows:

[0050] 1) The preparation of the vitrified bond grinding wheel is the same as the preparation method of step 1) in Example 1.

[0051] 2) The preparation of the resin liquid is the same as the method of step 2) in Example 1.

[0052] 3) Impregnation treatment

[0053] The ceramic bond grinding wheel of step 1) is placed in the prepared resin liquid and soaked at room temperature for 12 hours. The resin solution becomes thick (viscosity is 5286mPa·s). There is more resin liquid on the surface of the grinding wheel. After soaking, it is taken out and placed in an oven and kept at 95°C for 4 hours. After surface and inner and outer circle processing, a grinding wheel that can be used in normal production is obtained. Because there is more residual resin solution on the surface of the grinding wheel, the processing time is increased, which affects the production efficiency.

[0054] 2. Comparison

[0055] Comparative Example 1

[0056] The toughening method of the vitrified bond grinding wheel of this comparative example is as follows:

[0057] 1) The preparation of the vitrified bond grinding wheel is the same as the preparation method of step 1) in Example 1.

[0058] 2) Preparation of resin liquid

[0059] Pour 95% epoxy resin (brand: E42) into a container, slowly stir and heat to 100℃, then add 4.2% accelerator DMP-30, and finally add 0.8% anhydrous ethanol. After 30 minutes of heat preservation, the resin liquid gradually thickens (viscosity is 1580mPa·s). After more than 50 minutes of heat preservation, a small amount of resin liquid begins to solidify. At this time, the resin liquid is no longer suitable for impregnating grinding wheels. Reduce the heating temperature to 40℃, and keep the amount of accelerator and anhydrous ethanol unchanged. After 60 minutes of heat preservation, the resin liquid is relatively viscous (viscosity is 4268mPa·s). When the heat preservation is continued to 120 minutes, the resin liquid is still relatively viscous (viscosity is 2310mPa·s). Increasing the temperature can shorten the preparation time of the resin solution, but it may cause the resin solution to solidify faster. Lowering the temperature causes the viscosity of the resin solution to change slowly, affecting production efficiency.

[0060] 3) Impregnation treatment

[0061] The resin liquid with a viscosity of 1580 mPa·s was used for impregnation treatment. The ceramic bond grinding wheel of step 1) was immersed at room temperature for 7 hours. The impregnation was uneven and the grinding wheel was prone to collapse during use. For safety reasons, the grinding test could not be performed. After the immersion time was extended, the resin liquid began to become viscous and even solidified. The resin liquid could not penetrate into the interior of the grinding wheel at this time, and was not suitable for grinding wheel impregnation.

[0062] Comparative Example 2

[0063] The toughening method of the vitrified bond grinding wheel of this comparative example is as follows:

[0064] 1) The preparation of the vitrified bond grinding wheel is the same as the preparation method of step 1) in Example 1.

[0065] 2) Preparation of resin liquid

[0066] Pour 98% unsaturated polyester resin (brand: 3301 bisphenol A polyester resin) into a container, slowly stir and heat to 75°C, then add 1.5% accelerator cobalt isooctanoate, and finally add 0.5% anhydrous ethanol, keep warm for 40 minutes, and obtain a resin liquid (viscosity 232mPa·s).

[0067] 3) Impregnation treatment

[0068] The ceramic bond grinding wheel of step 1) was placed in the resin liquid prepared in step 2) and soaked at room temperature for 6 hours. After soaking, it was taken out and placed in an oven and kept at 110°C for 3 hours. After taking it out, it was found that the grinding wheel was not solidified. The insulation time was extended for 3 hours. It was visible to the naked eye that part of the grinding wheel was still unsolidified, and the grinding wheel could not be used for grinding test.

[0069] Comparative Example 3

[0070] The toughening method of the vitrified bond grinding wheel of this comparative example is as follows:

[0071] 1) The preparation of the vitrified bond grinding wheel is the same as the preparation method of step 1) in Example 1.

[0072] 2) Preparation of resin liquid

[0073] Pour 90% unsaturated polyester resin (brand: 3301 bisphenol A polyester resin) by mass into a container, slowly stir and heat to 75°C, then add 9% of the accelerator cobalt isooctanoate, and finally add 1% of anhydrous ethanol. The resin solution solidifies during the stirring process, and the resin solution is completely solidified after 3 hours. This formula is not suitable for grinding wheel impregnation.

[0074] 3. Experimental Examples

[0075] The toughened and untoughened ceramic bond grinding wheels of Example 1 and Example 2 were loaded into a grinding machine to grind stainless steel 316L externally, and the grinding performance is shown in Table 1. The hardness of the grinding wheel was graded according to the national standard GB / T2490-2018.

[0076] Table 1 Grinding performance of vitrified bond grinding wheels

[0077] Grinding wheel hardness Use line speed <![CDATA[Surface roughness R a > Frequency of repair Service life Without toughening treatment K 45M / s 0.24μm 10 pieces / repair 800 items Example 1 Q 65M / s 0.18μm 12 pieces / repair 950 items Example 2 Q 60M / s 0.19μm 13 pieces / repair 980 items

[0078] It can be seen from Table 1 that the various performance indicators of the ceramic bond grinding wheel are improved by toughening the ceramic bond grinding wheel. During the impregnation process, the resin liquid enters the gap between the ceramic bond and the abrasive. Through heating, the resin, the abrasive and the ceramic bond are cross-connected and solidified into one, which improves the toughness of the grinding wheel, can increase the use speed of the grinding wheel, and then improve the processing efficiency of the grinding wheel, reduce the surface roughness of the ground workpiece, and increase the service life of the grinding wheel. When grinding the workpiece, the high temperature of grinding causes the resin to melt and re-expose the pores. At the same time, the molten resin will take away some of the detached abrasives, grinding chips and heat, so that the frequency of grinding tool dressing is reduced, and the possibility of the grinding tool burning the workpiece during high-speed grinding is reduced, and better workpiece surface quality is obtained.

[0079] The toughened and untoughened ceramic bond grinding wheels of Example 3 and Example 4 were loaded into a grinding machine and cylindrically ground 4J29 (iron-nickel-cobalt glass-sealed alloy) material using a grinding machine. The grinding performance is shown in Table 2.

[0080] Table 2 Grinding performance of vitrified bond grinding wheels

[0081] Grinding wheel hardness Use line speed <![CDATA[Surface roughness R a > Frequency of repair Service life Without toughening treatment J 35M / s 0.20μm 5 pieces / repair 970 items Example 3 P 50M / s 0.16μm 12 pieces / repair 2113 items Example 4 P 50M / s 0.16μm 12 pieces / repair 2087 items

[0082] It can be seen from Table 2 that by toughening the ceramic bond grinding wheel, the hardness of the ceramic bond grinding wheel is increased from J grade to P grade. The increase in hardness greatly improves the frequency of grinding wheel dressing and service life. The use speed of the grinding wheel after toughening treatment is increased from 35M / s to 50M / s, which greatly improves production efficiency. It can be seen from Example 4 that compared with the untoughened treatment, although the correction frequency and service life can also be improved, compared with Example 3, extending the immersion time does not improve the grinding effect, but increases the processing time, resulting in a decrease in processing efficiency. During the grinding process, the resin takes away some of the detached abrasives and the ground chips, reduces the surface roughness of the workpiece, and obtains better surface quality.

[0083] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for toughening a vitrified bond grinding wheel, characterized in that: The method comprises the following steps: impregnating a ceramic bond grinding wheel in a resin liquid, and curing the mixture after the impregnation. The resin liquid comprises a thermosetting resin with a mass fraction of 94-96%, the thermosetting resin is selected from one of an epoxy resin and a polyester resin, and the viscosity of the resin liquid is 200-500 mPa·s.

2. The toughening method of a vitrified bond grinding wheel according to claim 1, characterized in that: The resin liquid consists of 94-96% by mass of a thermosetting resin, 4-8% by mass of a resin curing accelerator and 0.5-1% by mass of anhydrous ethanol.

3. The toughening method of a vitrified bond grinding wheel according to claim 1, characterized in that: The immersion treatment is performed at room temperature for 6 to 12 hours.

4. The toughening method of a vitrified bond grinding wheel according to claim 1, characterized in that: The curing is carried out by keeping the temperature at 60-120° C. for 2-4 hours.

5. The toughening method of a vitrified bond grinding wheel according to claim 1 or 2, characterized in that: The resin liquid is obtained by heating a thermosetting resin to 50-90° C., adding a resin curing accelerator and anhydrous ethanol, and maintaining the temperature for 0.5-1 hour.

6. The toughening method of a vitrified bond grinding wheel according to claim 1, characterized in that: The vitrified bond grinding wheel is obtained by mixing vitrified bond, abrasive and dextrin liquid or water glass, and then pressing and sintering.

7. The toughening method of a vitrified bond grinding wheel according to claim 6, characterized in that: The mass ratio of the ceramic binder to the abrasive is (10-15): (85-90), and the amount of dextrin liquid or water glass added is 1.5-2.5% of the total mass of the ceramic binder and the abrasive.

8. The toughening method of a vitrified bond grinding wheel according to claim 6, characterized in that: The sintering temperature is 1000-1100° C., and the sintering time is 5-8 hours.

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