Composite bonding agent, grinding block, grinding disc, grinding disc trimming method and application

Abstract

The application belongs to the technical field of grinding tools, and particularly relates to a composite binder, a grinding block, a grinding disc, a grinding disc trimming method and application. The composite binder comprises 22-36% of titanium carbide, 5-11.5% of fullerene, 35-55% of low-melting-point glass powder, 2.5-7.5% of organic silicon modified resin and 10-18% of polyimide resin in terms of mass fraction, and the low-melting-point glass powder has a melting point of 280-320 DEG C. By introducing titanium carbide, fullerene and glass powder, a composite phase state with organic-inorganic network through structure is formed, the self-sharpening property and heat resistance of the grinding block are increased, the holding force on the abrasive is improved, the hardness and strength of the grinding block are improved, the hardness of the grinding block can be adjusted by adjusting the mass ratio of titanium carbide and fullerene in the composite binder, fine grinding machining of workpieces is realized, machining size consistency is greatly improved, the chipping rate is reduced, and workpiece surface scratching and surface blocking burn are reduced.

Description

Technical Field

[0001] This invention relates to the field of grinding tool technology, specifically to a composite binder, grinding block, grinding disc, grinding disc dressing method and application. Background Technology

[0002] Powder metallurgy materials are commonly used in the manufacture of automotive parts such as gears, connecting rods, crankshafts, and valves; as well as in the manufacturing of many other components in the machinery, electronics, home appliance, and aerospace industries. Powder metallurgy materials are formed by pressing metallic, non-metallic, or two or more materials together using a molding process. While powder metallurgy materials can form composite structures with high hardness and strength during pressing and sintering, differences in pressing temperature, physical structures and crystal forms of the materials, and particle sizes result in gaps of varying sizes between particles. This leads to a loose internal crystal lattice structure with varying degrees of lattice defects, posing challenges to precision machining.

[0003] Resin-bonded diamond or hexagonal boron nitride (CBN) grinding discs paired with CNC double-end grinding machines for double-end grinding are the preferred solution for achieving high-precision, high-surface-quality, and high-stability machining of workpieces manufactured in batches of powder metallurgy materials. However, when performing double-end fine machining on hundreds of thousands of powder metallurgy workpieces, problems such as poor dimensional consistency, high chipping rate, severe scratches, and surface blockage and burning occur. Therefore, maintaining stable high-precision grinding, high yield, high consistent surface quality, and high-efficiency machining places high demands on composite-bonded diamond or CBN grinding discs, supporting equipment, and processing technology. In addition, the dressing of the grinding blocks is also an important factor affecting the achievement of efficient and stable grinding. Traditional dressing methods include mechanical grinding or abrasive impact dressing, but these two methods have long dressing times, low efficiency, and poor consistency of the dressing edge, which seriously affects the stable grinding of the workpiece.

[0004] To address the above challenges, existing technologies involve preparing resin-bonded diamond or CBN grinding discs with various properties. For example, grinding discs with large pores can be prepared using pore-forming agents to improve grinding self-sharpening properties, while grinding discs with self-lubrication or better heat resistance can be prepared by adding various lubricants or fillers. Chinese patent application CN116967947A, published on October 31, 2023, discloses a graphene resin-bonded grinding wheel for seamless steel pipes and its preparation method. The graphene resin-bonded grinding wheel is formed by hot pressing of the grinding wheel forming material. The grinding wheel forming material includes abrasive, binder, wetting agent and auxiliary materials. The binder is graphene-modified phenolic resin, which is composed of inorganic salt functional materials such as pyrite sulfide, cryolite, and potassium sulfate. Submicron-sized functional materials such as sulfides and fluorides are composite nucleated with polymer resin, which greatly improves the holding force between the binder and the abrasive. Furfural and cypress oil are used as wetting agents for the forming material, avoiding the addition of special materials with large pore structure design in the formula, so as to achieve the requirements of high-speed and high-temperature grinding under closed conditions.

[0005] However, the above methods still cannot achieve stable high-precision grinding, high yield, high consistent surface quality, and high-efficiency processing during fine grinding. Moreover, the above methods cannot achieve controllable hardness of the grinding wheel (i.e., grinding disc), thus failing to achieve controllable dressing process and the corresponding relationship between hardness and workpiece, resulting in the inability to guarantee the specific processing of rough grinding and fine grinding. Summary of the Invention

[0006] The purpose of this invention is to provide a composite binder that solves the problems of poor dimensional consistency, high chipping rate, severe scratches, and surface blockage and burns in the fine grinding of powder metallurgy workpieces in the prior art.

[0007] The second objective of this invention is to provide a grinding block that solves the problems of poor dimensional consistency, high chipping rate, severe scratches, and surface blockage and burns in the fine grinding of powder metallurgy workpieces in the prior art.

[0008] The third objective of this invention is to provide a grinding disc that solves the problems of poor dimensional consistency, high chipping rate, severe scratches, and surface blockage and burns that exist in the prior art when fine grinding powder metallurgy workpieces.

[0009] The fourth objective of this invention is to provide a grinding disc dressing method that solves the problems of long dressing time, low efficiency, and poor consistency of the dressing edge in the prior art.

[0010] The fifth objective of this invention is to provide an application of a grinding disc that solves the problems of poor dimensional consistency, high chipping rate, severe scratches, and surface blockage and burns in the fine grinding of powder metallurgy workpieces in the prior art.

[0011] To solve the above-mentioned technical problems, the technical solution of the composite binder of the present invention is as follows:

[0012] A composite binder, wherein the composite binder comprises 22-36% by mass of titanium carbide, 5-11.5% by mass of fullerene, 35-55% by mass of low-melting-point glass powder, 2.5-7.5% by mass of organosilicon modified resin and 10-18% by mass of polyimide resin, wherein the low-melting-point glass powder has a melting point of 280-320°C.

[0013] This invention improves upon existing technology by providing a composite binder. By adding fullerene to the composite binder, the microstructure of the resin is altered, forming nodes between resin bridges and increasing the resin's brittleness. This causes brittle fracture under grinding forces, increasing the self-sharpening property of the grinding block and enabling it to continuously and sharply grind the workpiece. Simultaneously, the good thermal conductivity of fullerene facilitates rapid heat transfer during grinding, preventing burns to the workpiece. Furthermore, the addition of low-melting-point glass powder to the composite binder, while lacking inherent viscosity, allows it to flow at its viscous flow temperature, co-flowing with the thermosetting resin and fusing with titanium carbide to form a composite phase with an organic-inorganic network structure. This enhances the abrasive's... The holding force of the binder is increased, thereby improving the hardness and strength of the grinding block. Furthermore, the inorganic non-metallic material composed of titanium carbide, fullerene, and glass powder effectively improves the heat resistance of the binder, increasing its heat resistance temperature by 50-100℃. In addition, the composite binder provided by this invention can control the hardness of the grinding block by adjusting the mass ratio of titanium carbide and fullerene. This allows powder metallurgy workpieces to be finely ground using grinding blocks of different hardnesses for different grinding requirements. For example, different hardness grinding blocks can be used for rough grinding, semi-fine grinding, fine grinding, and polishing processes, achieving high-gloss surface finish grinding, chip-free grinding, high-efficiency grinding, and high-gloss surface finish grinding. This greatly improves dimensional consistency, reduces chipping rate, and minimizes surface scratches and surface blockage burns on the workpiece.

[0014] To further control the hardness of the grinding block through the composition, preferably, the mass ratio of titanium carbide to fullerene is (2~3):1, or (3~3.5):1, or (3.5~4.5):1, or (4.5~5.5):1, or (5.5~7):1.

[0015] To further improve the holding power of the abrasive, preferably, the organosilicon modified resin is selected from one of organosilicon modified polyester resin, organosilicon modified polyimide resin, and organosilicon modified acrylic resin.

[0016] To further improve the high-temperature stability of the binder, preferably, the organosilicon modified resin has a thermal weight loss of <20% at 200℃; and the polyimide resin has a thermal weight loss of <10% at 200℃.

[0017] The technical solution of the grinding block of the present invention is as follows:

[0018] A grinding block comprising abrasive and the aforementioned composite binder.

[0019] The grinding block provided by this invention, by incorporating the aforementioned composite binder, features fullerenes that enhance its self-sharpening properties, enabling continuous and sharp grinding of the workpiece. Simultaneously, the good thermal conductivity of fullerenes facilitates rapid heat transfer during grinding, preventing burns to the workpiece. The low-melting-point glass powder in the composite binder flows together with the thermosetting resin and fuses with titanium carbide to form a composite phase with an organic-inorganic network structure, improving the holding force of the abrasive and thus increasing the hardness and strength of the grinding block. The inorganic non-metallic materials in the grinding blocks can effectively improve their heat resistance. Furthermore, by adjusting the mass ratio of titanium carbide and fullerene in the composite binder, the hardness of the grinding blocks can be controlled. This allows powder metallurgy workpieces to be finely ground using grinding blocks with different hardnesses for different grinding requirements. For example, different hardness grinding blocks can be used for rough grinding, semi-fine grinding, fine grinding, and polishing processes. This achieves high-gloss surface finish grinding, chip-free grinding, high-efficiency grinding, and high-gloss surface finish grinding, which can greatly improve the consistency of machining dimensions, reduce chipping rate, and reduce surface scratches and surface blockage burns on the workpiece.

[0020] To further improve the grinding performance of the abrasive, preferably, the abrasive is diamond or cubic boron nitride, and the particle size of the abrasive is 80#~2000#.

[0021] To further control the hardness of the grinding block through the grinding block preparation process, preferably, the grinding block is obtained by mixing abrasive and composite binder and then vacuum hot pressing, wherein the vacuum hot pressing temperature is 225~255℃ and the vacuum hot pressing pressure is 100~180kN.

[0022] To further enable the grinding blocks to exhibit different hardnesses, preferably, when the mass ratio of titanium carbide to fullerene in the composite binder is (2~3):1, the temperature of the vacuum hot pressing is 225~235℃, and the pressure of the vacuum hot pressing is 170~180kN, the hardness of the resulting grinding block is 35~45HRB.

[0023] When the mass ratio of titanium carbide to fullerene in the composite binder is (3~3.5):1, the temperature of the vacuum hot pressing is 240~245℃, and the pressure of the vacuum hot pressing is 150~160kN, the hardness of the resulting grinding block is 45~50HRB.

[0024] When the mass ratio of titanium carbide to fullerene in the composite binder is (3.5~4.5):1, the temperature of the vacuum hot pressing is 240~245℃, and the pressure of the vacuum hot pressing is 130~140kN, the hardness of the resulting grinding block is 50~55HRB.

[0025] When the mass ratio of titanium carbide to fullerene in the composite binder is (4.5~5.5):1, the temperature of the vacuum hot pressing is 240~245℃, and the pressure of the vacuum hot pressing is 110~120kN, the hardness of the resulting grinding block is 55~60HRB.

[0026] When the mass ratio of titanium carbide to fullerene in the composite binder is (5.5~7):1, the temperature of the vacuum hot pressing is 225~230℃, and the pressure of the vacuum hot pressing is 100~105kN, the hardness of the resulting grinding block is 60~62HRB.

[0027] The hardness of the grinding blocks is classified as follows: 35~45 HRB is classified as low hardness, 45~50 HRB as medium-low hardness, 50~55 HRB as medium hardness, 55~60 HRB as medium-high hardness, and 60~62 HRB as high hardness.

[0028] It should be noted that the mass ratio of titanium carbide to fullerene is (2~3):1, which means that when the mass of fullerene is 1 part, the mass of titanium carbide is: 2 parts ≤ titanium carbide mass < 3 parts; at this time, the hardness of the grinding block is 35~45HRB, which means 35HRB ≤ grinding block hardness < 45HRB. The subsequent mass ratio and hardness range are the same, and will not be repeated here.

[0029] The technical solution of the grinding disc of the present invention is as follows:

[0030] A grinding disc, the grinding disc comprising a base and grinding blocks disposed on the base.

[0031] The grinding disc of this invention uses the aforementioned grinding block, incorporating the aforementioned composite binder. This enhances the self-sharpening and heat resistance of the grinding block, improves its holding force on the abrasive, and consequently increases its hardness and strength. Furthermore, the hardness of the grinding block can be controlled by adjusting the mass ratio of titanium carbide and fullerene in the composite binder. Combined with different dressing processes, the flatness of the dressed grinding block can be reduced to <0.03 mm, further improving the consistency of abrasive cutting edge. This allows powder metallurgy workpieces to be precision ground using grinding blocks of different hardnesses for various grinding requirements. For example, different hardness grinding blocks can be used for rough grinding, semi-fine grinding, fine grinding, and polishing processes, achieving high-gloss surface finish grinding, chip-free grinding, high-efficiency grinding, and high-gloss surface finish grinding. This significantly improves dimensional consistency, reduces chipping rate, and minimizes surface scratches and surface blockage burns on the workpiece.

[0032] The technical solution of the grinding disc dressing method of the present invention is as follows:

[0033] A method for dressing a grinding disc involves ultrasonically treating the grinding disc in a dilute nitric acid solution with a concentration of 1.4-2.2%, wherein the frequency of the ultrasonic treatment is 200-600MHz and the duration of the ultrasonic treatment is 1.5-3.5h.

[0034] The grinding block dressing method of the present invention employs chemical ultrasonic treatment. It utilizes the fact that titanium carbide and low-melting-point glass powder in the grinding block are slightly soluble in dilute nitric acid solution. When the grinding block is ultrasonically treated in dilute nitric acid solution, as the titanium carbide and low-melting-point glass powder slowly dissolve, the cross-linked and solidified composite binder will decompose and undergo brittle fracture, and the surface binder will completely fall off, exposing the abrasive cutting edge. This allows the grinding disc to continuously perform sharp grinding. The dressing method of the present invention has a shorter dressing time, higher efficiency, and better consistency of the dressed edge compared to traditional mechanical grinding.

[0035] To further adapt to grinding blocks of different hardness and improve the consistency of edge emergence of grinding blocks of different hardness, preferably, when the grinding disc hardness is 35~45HRB, the frequency of the ultrasonic treatment is 200~250MHz, and the ultrasonic treatment time is 1.5~1.8h.

[0036] When the hardness of the grinding disc is 45~50HRB, the frequency of the ultrasonic treatment is 300~350MHz, and the duration of the ultrasonic treatment is 2~2.4h.

[0037] When the hardness of the grinding disc is 50~55HRB, the frequency of the ultrasonic treatment is 400~450MHz, and the duration of the ultrasonic treatment is 2.5~2.8h.

[0038] When the hardness of the grinding disc is 55~60HRB, the frequency of the ultrasonic treatment is 500~550MHz, and the duration of the ultrasonic treatment is 3~3.2h.

[0039] When the hardness of the grinding disc is 60~62HRB, the frequency of the ultrasonic treatment is 580~600MHz, and the duration of the ultrasonic treatment is 3.3~3.5h.

[0040] The technical solution for the application of the grinding disc of the present invention is as follows:

[0041] An application of a grinding disc, wherein the grinding disc is dressed using the grinding disc dressing method and then mounted on a grinding machine for grinding workpieces, wherein the flatness of the dressed grinding disc is <0.03mm.

[0042] The grinding disc of this invention can be used for grinding workpieces by assembling the prepared grinding blocks onto a grinding machine. The composite binder introduced into the grinding blocks increases their self-sharpening and heat resistance, improves their holding force on the abrasive, and thus increases their hardness and strength. The hardness of the grinding blocks can be controlled by adjusting the mass ratio of titanium carbide and fullerene in the composite binder. With different preparation processes, the flatness of the prepared grinding blocks can be made <0.03mm, further improving the consistency of abrasive cutting edge. This allows powder metallurgy workpieces to be finely ground using grinding blocks with different hardnesses for different grinding requirements. For example, different hardness grinding blocks can be used for rough grinding, semi-fine grinding, fine grinding, and polishing processes to achieve high-gloss surface finish grinding, chip-free grinding, high-efficiency grinding, and high-gloss surface finish grinding. This can greatly improve the consistency of machining dimensions, reduce the chipping rate, and reduce surface scratches and surface blockage burns on the workpiece.

[0043] In order to further adapt to grinding blocks of different hardness, improve the grinding accuracy of workpieces, avoid surface scratches and burns, and achieve stable grinding, preferably, the grinding machine is a double-sided grinding machine, and the grinding discs are mounted on the double-sided grinding machine as the upper and lower discs of the double-sided grinding machine respectively.

[0044] When the hardness of the upper and lower plates is 35~45HRB, the rotation speed of the upper plate is 10~12rpm, the rotation speed of the lower plate is 8~10rpm, the grinding disc dressing time interval is 18~20h, and the upper and lower plates swapping time interval is 48~50h.

[0045] When the hardness of the upper and lower plates is 45~50HRB, the rotation speed of the upper plate is 14~15rpm, the rotation speed of the lower plate is 12~13rpm, the grinding disc dressing time interval is 13~14h, and the upper and lower plates swapping time interval is 55~58h.

[0046] When the hardness of the upper and lower plates is 50~55HRB, the rotation speed of the upper plate is 16~17rpm, the rotation speed of the lower plate is 14~15rpm, the grinding disc dressing time interval is 11~12h, and the upper and lower plates swapping time interval is 60~68h.

[0047] When the hardness of the upper and lower plates is 55~60HRB, the rotation speed of the upper plate is 18~19rpm, the rotation speed of the lower plate is 16~17rpm, the grinding disc dressing time interval is 9~10h, and the upper and lower plates swapping time interval is 70~80h.

[0048] When the hardness of the upper and lower plates is 60~62HRB, the rotation speed of the upper plate is 19~20rpm, the rotation speed of the lower plate is 17~18rpm, the grinding disc dressing time interval is 8~9h, and the upper and lower plates swapping time interval is 81~96h.

[0049] To further improve the adaptability of the workpiece, preferably, the workpiece is prepared by powder metallurgy. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the molecular structure of fullerene;

[0051] Figure 2 This is a diagram showing the test position of the grinding block of the present invention during hardness testing;

[0052] Figure 3 This is a schematic diagram of the internal structure of the grinding block obtained in Example 4. Detailed Implementation

[0053] The technical concept of the composite binder of the present invention is as follows:

[0054] A composite binder, wherein the composite binder comprises 22-36% by mass of titanium carbide, 5-11.5% by mass of fullerene, 35-55% by mass of low-melting-point glass powder, 2.5-7.5% by mass of organosilicon modified resin and 10-18% by mass of polyimide resin, wherein the low-melting-point glass powder has a melting point of 280-320°C.

[0055] First, due to the large surface area and low rotation speed of the grinding disc, the grinding blocks mounted on it have high grinding dullness. If the hardness of different points on the surface of the grinding block is inconsistent, the bonding agent's holding force on the abrasive will vary. Even using the same dressing process, it is impossible to achieve a consistent surface finish. This will result in some points having high surface finish heights and others having low surface finish heights. Consequently, some workpieces will have low removal efficiency, while others will have high removal efficiency. Some will suffer chipping and scratches, while others, due to poor diamond surface finish, will not expose sharp edges, leading to compression burns. Second, for different grinding processes, such as rough grinding, semi-finish grinding, ... In fine grinding and polishing processes, grinding blocks with the same bond hardness cannot be used. For rough grinding, which primarily removes excess material, a high grinding sharpness is required to remove large amounts. In this case, a low bond hardness is needed to effectively remove used abrasive grains during grinding, exposing new abrasive cutting edges and ensuring the grinding wheel continues to grind the workpiece sharply. For fine grinding or polishing, which primarily removes small amounts of material, a lower sharpness is required to prevent the bond from becoming too soft, causing premature abrasive grain detachment and forming free-state abrasive grains that scratch the workpiece during fine grinding. Therefore, for different grinding processes and for finer grinding of workpieces of different sizes, grinding blocks with controllable bond hardness must be selected to achieve dimensionally stable grinding.

[0056] This invention incorporates fullerenes into a composite binder, resulting in a microscopic molecular structure resembling a soccer ball. The molecular structure of the fullerene is as follows: Figure 1As shown, this process can alter the microstructure of the resin, forming nodes between resin bridges and increasing its brittleness. This causes brittle fracture under grinding forces, increasing the self-sharpening properties of the grinding block and enabling it to continuously and sharply grind the workpiece. Simultaneously, the good thermal conductivity of fullerenes facilitates rapid heat transfer during grinding, preventing burns to the workpiece. Adding low-melting-point glass powder (melting point 280-320℃) to the composite binder, while lacking inherent viscosity, allows it to flow at its viscous flow temperature. This allows the low-melting-point glass powder to flow alongside the thermosetting resin and fuse with titanium carbide, forming a composite phase with an organic-inorganic network structure. This enhances the holding power of the abrasive. This improves the hardness and strength of the grinding blocks; and inorganic non-metallic materials such as titanium carbide, fullerene, and glass powder can effectively improve the heat resistance of the binder, increasing its heat resistance temperature by 50-100℃. In addition, the binder provided by this invention can control the hardness of the grinding blocks by adjusting the mass ratio of titanium carbide and fullerene, enabling powder metallurgy workpieces to be finely ground using grinding blocks with different hardnesses for different grinding requirements. For example, different hardness grinding blocks can be used for rough grinding, semi-fine grinding, fine grinding, and polishing processes, achieving high-gloss surface finish grinding, chip-free grinding, high-efficiency grinding, and high-gloss surface finish grinding, which can greatly improve the consistency of machining dimensions, reduce the chipping rate, and reduce surface scratches and surface blockage burns on the workpiece.

[0057] In a specific embodiment, the glass transition temperature of the low melting point glass powder is 230℃-250℃, and the melting point is 280-320℃; the melting point of the organic modified silicone resin is 230-300℃, and the melting point of the polyimide resin is 250-300℃.

[0058] In a specific embodiment, the purity of the titanium carbide, fullerene, and low-melting-point glass powder is 99.9%, and the magnetic material content of each component is <0.5%.

[0059] In a specific embodiment, the density of the organosilicon-modified resin is 1.28-1.30 g / cm³. 3 The density of polyimide resin is 1.30-1.38 g / cm³. 3 The density of titanium carbide is 4.93 g / cm³. 3 Fullerenes have a density of 1.8-2.0 g / cm³. 3 The density of low-melting-point glass powder is 2.0-2.5 g / cm³. 3 .

[0060] In a specific implementation, 200℃ thermogravimetric analysis refers to the mass loss rate of the resin at 200℃ during thermogravimetric analysis, which includes DCS and TG tests.

[0061] In a specific embodiment, the particle size of the titanium carbide, fullerene, and low-melting-point glass powder is 100~1500#.

[0062] A grinding block comprising abrasive and the aforementioned composite binder.

[0063] An application of a grinding block, wherein the grinding disc is dressed using the grinding disc dressing method and then assembled on a grinding machine for grinding workpieces, wherein the flatness of the dressed grinding disc is <0.03mm.

[0064] In specific embodiments, the double-sided grinding machine can be a German Pitwater CNC double-sided grinding machine, a Swiss Starley CNC grinding machine, a Korean AM CNC grinding machine, or a domestically produced CNC double-sided grinding machine, etc. The grinding disc size can be prepared according to the needs of different grinding machines, and the grinding disc size can be: diameter 1500mm, 1200mm, 1050mm, 1000mm, 720mm, 700mm, 630mm; the shape of the grinding disc is not limited and can also be prepared according to the needs of different grinding machines. For example, the grinding disc can be round, hexagonal, pentagonal, elliptical, square, and other shapes.

[0065] In a specific embodiment, the grinding block is bonded to the substrate with a metal adhesive to form a grinding disc, which is then assembled in a grinding machine to achieve efficient, high-precision, non-destructive, and stable processing of powder metallurgy workpieces.

[0066] The embodiments of the present invention will be further described below with reference to specific examples. Unless otherwise specified, the chemical reagents involved in the following examples are all commercially available analytical grade products.

[0067] I. Specific Embodiments of the Composite Binder of the Present Invention

[0068] The information on the raw material manufacturers used in the composite binder of the present invention is shown in Table 1, and the composition formula of the binder is shown in Table 2.

[0069] Table 1 Raw Material Manufacturer Information

[0070]

[0071] Table 2 Composition and Formulation of Composite Binder

[0072]

[0073] The composite binder in Example 1 is composed of 25% titanium carbide, 11.5% fullerene, 51% low-melting-point glass powder, 2.5% organosilicon modified resin and 10% polyimide resin by mass fraction, wherein the melting point of the low-melting-point glass powder is 280-290℃.

[0074] The composite binder in Example 2 consists of 30% titanium carbide, 8% fullerene, 45% low-melting-point glass powder, 5% organosilicon modified resin and 12% polyimide resin by mass fraction, wherein the melting point of the low-melting-point glass powder is 280-290℃.

[0075] The composite binder in Example 3 consists of 36% titanium carbide, 6% fullerene, 39% low-melting-point glass powder, 3.5% organosilicon modified resin and 15.5% polyimide resin by mass fraction, wherein the low-melting-point glass powder has a melting point of 280-290℃.

[0076] II. Specific Embodiments of the Grinding Block of the Present Invention

[0077] The abrasive block of the present invention comprises an abrasive and a binder of any one of Examples 1-3, wherein the abrasive is diamond or CBN and the abrasive particle size is 80#~2000#.

[0078] The grinding block of the present invention is obtained by vacuum hot pressing after mixing abrasive and composite binder. The raw materials and vacuum hot pressing process conditions used in each embodiment are shown in Table 3.

[0079] Table 3. Raw materials and vacuum hot pressing process used in grinding block preparation

[0080]

[0081] The hardness of the grinding block was tested using a Rockwell hardness tester. During the test, nine points were taken on the surface of the grinding block for hardness measurement. The test locations are as follows: Figure 2 As shown, the final hardness is the average of 9 points.

[0082] A schematic diagram of the internal structure of the grinding block obtained in Example 4 is shown below. Figure 3 As shown, fullerenes form nodes between resin bridge segments. Low-melting-point glass powder undergoes high-speed molecular vibration at 220℃-260℃, resulting in flow. The low-melting-point glass powder can flow together with thermosetting resin and melt into titanium carbide, forming a composite phase with an organic-inorganic network structure. This composite phase can improve the abrasive's ( Figure 3 The triangle in the image represents the holding force of the abrasive, thereby increasing the hardness and strength of the abrasive block.

[0083] III. Specific Embodiments of the Grinding Disc of the Invention

[0084] The grinding discs in Examples 7-9 include a substrate and grinding blocks disposed on the substrate. The grinding blocks in Examples 7-9 are the grinding blocks prepared in Examples 4-6, respectively.

[0085] IV. Specific Embodiments of the Grinding Disc Dressing Method of the Present Invention

[0086] In an embodiment of the grinding disc dressing method of the present invention, the grinding discs of Examples 7 to 9 were subjected to ultrasonic treatment in a dilute nitric acid solution with a concentration of 1.4 to 2.2%, and the dressing process parameters are shown in Table 4.

[0087] Table 4 Grinding process of grinding disc

[0088]

[0089] V. Specific Embodiments of the Application of the Grinding Disc of the Present Invention

[0090] In an embodiment of the application of the grinding disc of the present invention, the grinding disc is dressed using the grinding disc dressing method described above and then mounted on a grinding machine for grinding workpieces. The flatness of the dressed grinding disc is <0.03mm. The grinding machine is a double-sided grinding machine, and the grinding disc is mounted on the double-sided grinding machine as the upper and lower discs respectively. Parameters such as the rotation speed, direction of rotation, grinding disc rest time interval, and upper and lower disc swapping time interval are set for the upper and lower discs, allowing the workpiece to undergo different grinding processes, achieving high-precision, scratch-free, burn-free, and stable processing of powder metallurgy workpieces. The processing parameters for grinding workpieces using the double-sided grinding machine are shown in Table 5. The grinding disc dressing time interval refers to the time after grinding the workpiece following the initial dressing, during which the workpiece is dressed again. The dressing method used is the same as the initial dressing method, ensuring that the flatness is <0.03mm before completion.

[0091] Table 5 Machining parameters during grinding

[0092]

[0093] The grinding method described in Example 13 is used for rough grinding of powder metallurgy workpieces. The single feed rate can reach 1.0-1.5 mm, with no burns, scratches, or chipping. The dimensional accuracy (grinding flatness) can reach 0.05 mm.

[0094] The grinding method described in Example 14 was used for semi-finish grinding of powder metallurgy workpieces. The single feed rate could reach 0.5-0.8 mm, and the surface finish of the ground material was R. a The surface area should be 0.1-0.2 mm, with no burns, scratches, or chips.

[0095] The grinding method described in Example 15 was used for fine grinding of powder metallurgy workpieces. The single feed rate could reach 0.3-0.5 mm, and the surface finish of the ground material was R. a The sample size should be 0.05-0.01 mm, with no burns, scratches, or chips.

[0096] The grinding disc application method provided by this invention enables different grinding processes to be used for workpieces with different physical configurations prepared by powder metallurgy, such as rough grinding, semi-fine grinding, fine grinding and polishing processes, which can greatly improve the consistency of processing dimensions, reduce the chipping rate, and reduce surface scratches and surface blockage burns on the workpiece.

[0097] VI. Experimental Examples

[0098] This experimental example illustrates the gradient control of grinding block hardness. By adjusting the mass ratio of titanium carbide and fullerene and the vacuum hot pressing process, the hardness of the grinding block can be gradient controlled. The specific control methods are shown in Table 6.

[0099] Table 6. Effects of raw material mass ratio and vacuum hot pressing process on hardness.

[0100]

[0101] As can be seen from Table 6, the gradient control of the hardness of the grinding block was achieved by controlling the above parameters, where 5#, 3#, and 1# are the grinding blocks obtained by the grinding block preparation methods of Examples 4-6, respectively.

[0102] Using different dressing processes with grinding discs of different hardness can ensure that the cutting edge height of the grinding blocks is consistent and the cutting edge effect is good, thereby achieving efficient and stable grinding. The dressing processes for grinding discs of different hardness are shown in Table 7.

[0103] Table 7 Dressing processes for grinding discs of different hardness

[0104]

[0105] Among them, 10#, 8#, and 6# are the grinding disc finishing processes of Examples 10-12, respectively.

[0106] Grinding discs of different hardness are combined with different dressing processes and assembled on a double-sided grinding machine as the upper and lower discs of the grinding machine. The flatness of the grinding discs after dressing is <0.03mm. The upper and lower discs use grinding discs of the same hardness grade. The processing parameters for grinding the workpiece are shown in Table 8.

[0107] Table 8 Machining parameters for grinding

[0108]

[0109] By setting parameters such as different rotation speeds of the upper and lower grinding discs, opposite rotation directions of the upper and lower discs, time intervals for switching between the upper and lower discs, and frequency of dressing time for grinding discs of different hardness, high-precision, scratch-free, burn-free, and stable processing of powder metallurgy materials can be achieved. This allows for different grinding processes to be used for workpieces with different physical configurations prepared by powder metallurgy, such as rough grinding, semi-finish grinding, fine grinding, and polishing, which can greatly improve the consistency of machining dimensions, reduce the chipping rate, and reduce surface scratches and surface blockage burns on the workpiece. The grinding parameters for 15#, 13#, and 11# are the grinding parameters for Examples 13-15, respectively.

[0110] Finally, it should be noted that the above description 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 foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A grinding block, characterized in that, The grinding block is obtained by vacuum hot pressing after mixing abrasive and composite binder. The composite binder is composed of 22-36% titanium carbide, 5-11.5% fullerene, 35-55% low melting point glass powder, 2.5-7.5% organosilicon modified resin and 10-18% polyimide resin by mass fraction. The melting point of the low melting point glass powder is 280-320℃. When the mass ratio of titanium carbide to fullerene in the composite binder is (2~3):1, the temperature of the vacuum hot pressing is 225~235℃, the pressure of the vacuum hot pressing is 170~180kN, the hardness of the grinding block obtained at this time is 35~45HRB. When the mass ratio of titanium carbide to fullerene in the composite binder is (3~3.5):1, the temperature of the vacuum hot pressing is 240~245℃, and the pressure of the vacuum hot pressing is 150~160kN, the hardness of the resulting grinding block is 45~50HRB. When the mass ratio of titanium carbide to fullerene in the composite binder is (3.5~4.5):1, the temperature of the vacuum hot pressing is 240~245℃, and the pressure of the vacuum hot pressing is 130~140kN, the hardness of the resulting grinding block is 50~55HRB. When the mass ratio of titanium carbide to fullerene in the composite binder is (4.5~5.5):1, the temperature of the vacuum hot pressing is 240~245℃, and the pressure of the vacuum hot pressing is 110~120kN, the hardness of the resulting grinding block is 55~60HRB. When the mass ratio of titanium carbide to fullerene in the composite binder is (5.5~7):1, the temperature of the vacuum hot pressing is 225~230℃, and the pressure of the vacuum hot pressing is 100~105kN, the hardness of the resulting grinding block is 60~62HRB.

2. The grinding block as described in claim 1, characterized in that, The abrasive is diamond or cubic boron nitride.

3. A grinding disc, characterized in that, The grinding disc includes a base and a grinding block disposed on the base, wherein the grinding block is the grinding block as described in any one of claims 1-2.

4. A method for dressing a grinding disc as described in claim 3, characterized in that, The grinding disc is subjected to ultrasonic treatment in a dilute nitric acid solution with a concentration of 1.4-2.2%, the ultrasonic treatment frequency is 200-600MHz, and the ultrasonic treatment time is 1.5-3.5h.

5. The grinding disc dressing method as described in claim 4, characterized in that, When the hardness of the grinding disc is 35~45HRB, the frequency of the ultrasonic treatment is 200~250MHz, and the duration of the ultrasonic treatment is 1.5~1.8h.

6. The grinding disc dressing method as described in claim 4, characterized in that, When the hardness of the grinding disc is 45~50HRB, the frequency of the ultrasonic treatment is 300~350MHz, and the duration of the ultrasonic treatment is 2~2.4h.

7. The grinding disc dressing method as described in claim 4, characterized in that, When the hardness of the grinding disc is 50~55HRB, the frequency of the ultrasonic treatment is 400~450MHz, and the duration of the ultrasonic treatment is 2.5~2.8h.

8. The grinding disc dressing method as described in claim 4, characterized in that, When the hardness of the grinding disc is 55~60HRB, the frequency of the ultrasonic treatment is 500~550MHz, and the duration of the ultrasonic treatment is 3~3.2h.

9. The method for dressing a grinding disc as described in claim 4, characterized in that, When the hardness of the grinding disc is 60~62HRB, the frequency of the ultrasonic treatment is 580~600MHz, and the duration of the ultrasonic treatment is 3.3~3.5h.

10. An application of the grinding disc as described in claim 3, characterized in that, The grinding disc is dressed using the dressing method described in any one of claims 4-9 and then mounted on a grinding machine for grinding workpieces. The flatness of the dressed grinding disc is <0.03mm.

11. The application of the grinding disc as described in claim 10, characterized in that, The grinding machine is a double-sided grinding machine, and the grinding discs are assembled on the double-sided grinding machine as the upper and lower discs of the double-sided grinding machine, respectively; When the hardness of the upper and lower plates is 35~45HRB, the rotation speed of the upper plate is 10~12rpm, the rotation speed of the lower plate is 8~10rpm, the grinding disc dressing time interval is 18~20h, and the upper and lower plates swapping time interval is 48~50h. When the hardness of the upper and lower plates is 45~50HRB, the rotation speed of the upper plate is 14~15rpm, the rotation speed of the lower plate is 12~13rpm, the grinding disc dressing time interval is 13~14h, and the upper and lower plates swapping time interval is 55~58h. When the hardness of the upper and lower plates is 50~55HRB, the rotation speed of the upper plate is 16~17rpm, the rotation speed of the lower plate is 14~15rpm, the grinding disc dressing time interval is 11~12h, and the upper and lower plates swapping time interval is 60~68h. When the hardness of the upper and lower plates is 55~60HRB, the rotation speed of the upper plate is 18~19rpm, the rotation speed of the lower plate is 16~17rpm, the grinding disc dressing time interval is 9~10h, and the upper and lower plates swapping time interval is 70~80h. When the hardness of the upper and lower plates is 60~62HRB, the rotation speed of the upper plate is 19~20rpm, the rotation speed of the lower plate is 17~18rpm, the grinding disc dressing time interval is 8~9h, and the upper and lower plates swapping time interval is 81~96h.

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