Preparation method of novel electroplated grinding wheel

Abstract

The invention belongs to the technical field of grinding wheels, and mainly relates to a novel electroplated grinding wheel preparation method which comprises the following steps: step 1, electroplating the surface layer of a grinding material to form a metal coating; secondly, the electroplated abrasive material is electroplated on nickel foil paper again; thirdly, the grinding wheel base body is coated with resin, and then the nickel foil paper is attached to the organic epoxy resin around the grinding wheel base body; 4, curing the nickel foil paper on the resin through a mold pressing process to form dense combination; and step 5, removing excess resin after compression molding. Through multiple mechanisms of metal coating anchoring, flexible carrier transition, resin chemical crosslinking and mould pressing densification, the limitation that a traditional electroplated grinding wheel singly depends on metal coating combination is broken through, and the grinding material bonding strength is remarkably improved from the three dimensions of interface mechanics, chemical action and structural stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of grinding wheels, and mainly relates to a preparation method of a new type of electroplated grinding wheel. Background Art

[0002] An electroplated grinding wheel is a superhard grinding tool that fixes abrasive grains (such as diamond, CBN, etc.) on the surface of a grinding wheel base through an electrochemically deposited process. It has the characteristics of high grinding efficiency, good machining accuracy, wide application range, etc., and is widely used in fields such as aerospace, automobile manufacturing, precision molds, and semiconductor processing. The traditional electroplated grinding wheel preparation process mainly includes steps such as substrate pretreatment, plating solution preparation, abrasive loading, and fixing by electroplating metals (such as nickel, nickel-cobalt alloy).

[0003] With the processing requirements of difficult-to-grind materials such as titanium alloys and ceramics, there is an urgent need for a new preparation method of electroplated grinding wheels that can simultaneously solve problems such as the bonding strength of abrasive grains, distribution uniformity, environmental protection, and adaptability to complex shapes, while reducing the preparation cost and improving process stability.

[0004] Although electroplated grinding wheels are widely used in industry, the traditional preparation methods still have the following technical bottlenecks: 1. Insufficient bonding strength: The abrasive grains of traditional single-layer electroplated grinding wheels are only fixed by being wrapped with a metal coating. During high-speed and heavy-load grinding, the abrasive grains are prone to falling off, resulting in a short service life of the grinding wheel and poor machining stability.

[0005] 2. Uneven distribution of abrasive grains: Existing abrasive loading processes (such as sedimentation method, spraying method) are difficult to achieve uniform arrangement of abrasive grains, resulting in local accumulation or lack of abrasive grains, which affects the surface quality of machining.

[0006] 3. Poor adaptability to complex shapes: Traditional electroplating processes are difficult to achieve high-precision arrangement of abrasive grains on the surface of special-shaped substrates (such as microgrooves, curved surfaces), which limits their application in the field of precision machining.

[0007] 4. Difficulty in preparing multi-layer grinding wheels: Preparing multi-layer electroplated grinding wheels requires repeated abrasive loading and electroplating steps, with a long process cycle, and the interlayer bonding force is easily affected by the coating stress. Summary of the Invention

[0008] The present invention provides a preparation method of a new type of electroplated grinding wheel to solve the problem of insufficient bonding strength of abrasives on electroplated grinding wheels in the prior art.

[0009] To solve the above problems, the present invention adopts the following technical solutions: A preparation method of a new type of electroplated grinding wheel includes the following steps: Step 1: Electroplate a metal coating on the surface of the abrasive; Step 2: Electroplate the electroplated abrasive on a nickel foil paper again; Step 3: Coat the grinding wheel substrate with resin, and then wrap the nickel foil around the grinding wheel substrate and stick it on the organic epoxy resin; Step 4: Curing the nickel foil on the resin through a molding process to form a dense bond; Step 5: Remove excess resin after molding.

[0010] It has the following beneficial effects: through the multiple mechanisms of "metal coating anchoring, flexible carrier transition, resin chemical cross-linking, and molding densification", it breaks through the limitation of traditional electroplating grinding wheels that rely solely on metal coating bonding, and significantly improves the abrasive bonding strength from three dimensions: interface mechanics, chemical action, and structural stability.

[0011] Furthermore, the abrasive is CBN abrasive.

[0012] It has the following beneficial effects: Under the metal coating, the hard and brittle CBN abrasive particles can buffer the grinding impact through the plastic deformation ability of the metal coating, avoiding the bonding failure caused by the direct force fracture of the particles; CBN abrasives have excellent chemical stability in a neutral or weakly alkaline environment and are not easy to react chemically with electroplated metals or resins, thus avoiding a decrease in bonding strength due to interface corrosion.

[0013] Furthermore, the abrasive is diamond.

[0014] Furthermore, the CBN abrasive grain size is 140 / 170.

[0015] It has the following beneficial effects: CBN abrasive particle size 140 / 170 belongs to medium to fine particle size, and the fine cutting edge can reduce the single grinding depth and the impact force borne by a single particle, thereby reducing the risk of abrasive-metal coating interface falling off due to overload.

[0016] Furthermore, the depth of the abrasive penetrating into the resin is one third of the abrasive diameter.

[0017] The invention has the following beneficial effects: by controlling the length of the force arm (exposed height) and the holding volume, the grinding load is evenly distributed on the "abrasive-coating-resin" interface to avoid stress concentration.

[0018] Furthermore, the nickel foil has a thickness of 0.05 mm.

[0019] Furthermore, the resin is an organic epoxy resin.

[0020] It has the following beneficial effects: the organic epoxy resin molecular structure contains a large number of polar groups (such as hydroxyl groups and ether bonds), which can form chemical bonds (such as hydrogen bonds and covalent bonds) with the grinding wheel matrix and the abrasive surface, significantly improving the interfacial bonding strength; After curing, the epoxy resin forms a three-dimensional network structure, which can resist the erosion of acid and alkali components in grinding fluids (such as oil-based cutting fluids and water-based coolants), and avoid the loosening of abrasives caused by resin degradation.

[0021] Furthermore, the diameter of the grinding wheel base body is 100 mm.

[0022] Furthermore, in the molding process, the temperature is 100 - 200 °C and the pressure is 5 - 20 MPa.

[0023] Furthermore, the metal coating is a nickel coating.

[0024] It has the following beneficial effects: It is easy to form a microcrystalline coating on the surface of nickel and its alloys through electroplating. The atomic arrangement of the coating has a certain compatibility with the crystal structure of CBN abrasives (cubic boron nitride). The interface combination can be enhanced through the dual effects of physical adsorption (van der Waals force) and chemical adsorption (metallic bond); During the electroplating process, a pore-free, uniform and dense nickel coating structure can be formed by controlling the current density, avoiding stress concentration. The dense nickel coating can effectively wrap the edges and corners of CBN abrasives, and has a stronger ability to withstand shear forces during grinding, which can delay the process of abrasives being "pulled out" from the metal coating. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the structure of CBN abrasives penetrating into the resin; Figure 2 It is a schematic diagram of the structure of the grinding wheel; Figure 3 It is for Figure 2 The enlarged view of part A in

[0026] Description of the Reference Numerals in the Drawings: 1. Grinding wheel base body; 2. Organic epoxy resin; 3. CBN abrasive; 4. Metal coating; 5. Nickel foil paper. Detailed Embodiments

[0027] As Figures 1-3 shown, a method for preparing a new type of electroplated grinding wheel includes the following steps: Step 1: Electroplate a metal coating 4 on the surface layer of CBN abrasives 3. In this embodiment, the metal coating 4 is a nickel coating or a nickel alloy coating.

[0028] By electroplating a layer of metal on the surface of CBN abrasives 3, using the rough surface or microporous structure of the metal coating 4 to form a "mechanical bite" with the subsequent metal coating 4, similar to the anchoring effect of steel bars in concrete, to prevent the abrasives from directly falling off from the coating.

[0029] A microcrystalline coating is formed on the surface of nickel and its alloys through electroplating. The atomic arrangement of the coating has a certain compatibility with the crystal structure of CBN abrasive 3 (cubic boron nitride), and the interfacial bonding can be enhanced through the dual actions of physical adsorption (van der Waals force) and chemical adsorption (metallic bond). For example, the active nickel atoms in the nickel coating can form weak chemical bonds with the boron and nitrogen atoms on the surface of CBN abrasive 3, increasing the bonding strength between the abrasive and the metal coating 4 compared to a pure copper coating, and reducing the risk of abrasive detachment during high-speed rotation.

[0030] During electroplating, the nickel coating can form a pore-free, uniform, and dense structure by controlling the current density, avoiding stress concentration caused by defects in traditional metal coatings 4 (such as loose iron coatings). The dense nickel layer can effectively wrap the edges of CBN abrasive 3, having a stronger ability to withstand shear forces during grinding and delaying the process of abrasive "pulling out" from the metal coating 4.

[0031] Step 2: Electroplate the already electroplated abrasives onto a nickel foil 5 with a thickness of 0.05 mm.

[0032] The nickel foil 5 serves as an intermediate carrier. By electroplating, CBN abrasive 3 is fixed on its surface, forming a composite layer of "abrasive - metal coating 4 - nickel foil 5". The nickel foil 5 has both flexibility and high strength, which can buffer the stress generated by the difference in thermal expansion coefficients between the abrasive and the grinding wheel base 1, avoiding interface cracking.

[0033] CBN abrasive 3 is an insulator itself, but it can become a conductor after the surface metal coating 4. Subsequently, it can form a good electrical connection with the nickel foil 5, ensuring uniform current distribution during secondary electroplating, avoiding abrasive accumulation or missing plating caused by local poor conductivity, and improving the consistency of abrasive fixation.

[0034] Compared with the traditional process of directly electroplating onto the grinding wheel base 1, electroplating the abrasives onto the nickel foil 5 first enables batch pretreatment, ensuring uniform abrasive distribution and controllable density, and avoiding uneven bonding force caused by local abrasive accumulation or sparseness.

[0035] Step 3: Coat the grinding wheel base 1 with resin, and then paste the nickel foil 5 around the grinding wheel base 1 onto the organic epoxy resin 2. In this embodiment, the diameter of the grinding wheel base 1 is 100 mm.

[0036] The resin coated on the surface of the grinding wheel base 1 has strong adhesiveness. It can firmly bond the nickel foil 5 to the base through the simultaneous actions of physical winding (filling the abrasive gaps) and chemical crosslinking (reacting with the metal coating 4). For example, the epoxy groups in the epoxy resin can form chemical bonds with the oxides on the metal surface.

[0037] The metal grid structure of the nickel foil paper 5 can be fully infiltrated by the resin, forming an interlocking structure of "resin-metal mesh-abrasive", similar to the combination of steel bars and concrete in reinforced concrete, significantly enhancing the interfacial shear strength.

[0038] In this embodiment, the grinding wheel base 1 is an aluminum alloy base.

[0039] In other embodiments, the grinding wheel base 1 is a steel base.

[0040] Step 4: Cure the nickel foil paper 5 on the resin by a molding process to form a dense bond. In this embodiment, the temperature in the molding process is 100 - 200 °C, and the pressure is 5 - 20 MPa.

[0041] The pressure applied during the molding process forces the resin to fully fill the gap between the abrasive and the nickel foil paper 5, and squeezes the interface between the metal coating 4 and the resin, reducing pores and gaps and forming a defect-free dense layer. The pressure can also promote the diffusion between the metal coating 4 and the resin molecules, forming a closer physical adsorption layer.

[0042] Heating accelerates the crosslinking and curing of the resin, and may also trigger an interfacial chemical reaction between the metal coating 4 and the resin (such as the formation of ester bonds), further enhancing the chemical bonding force. For example, the oxide film on the surface of the nickel coating at high temperature can react with the anhydride curing agent in the epoxy resin to form a covalent bond.

[0043] Step 5: Remove the excess resin after molding.

[0044] In the traditional process, the excess resin may form "weak protrusions", which are prone to cracking and falling off under the grinding stress. After removing the excess resin, the bonding interface of the abrasive, nickel foil paper 5 and the base is smoother, the stress distribution is more uniform, and the internal stress concentration caused by the excessive thickness of the local resin is reduced.

[0045] This method breaks through the limitation of the traditional electroplated grinding wheel that solely relies on the bonding of the metal coating 4 through multiple mechanisms of "metal coating 4 anchoring, flexible carrier transition, resin chemical crosslinking, and molding densification", and significantly improves the abrasive bonding strength from three dimensions of interfacial mechanics, chemical action, and structural stability.

[0046] In this embodiment, the abrasive is the CBN abrasive 3. Under the wrapping of the metal coating 4, the brittle CBN abrasive 3 particles buffer the grinding impact through the plastic deformation ability of the metal coating 4, avoiding the bonding failure caused by the direct force on the particles resulting in cracking.

[0047] The high wear resistance of the CBN abrasive 3 prolongs the life of the abrasive, and the bonding interface between the metal coating 4 and the resin can remain intact for a longer time, indirectly improving the overall bonding strength.

[0048] The CBN abrasive 3 has excellent chemical stability in a neutral or weakly alkaline environment and is not prone to chemical reactions with electroplated metals or resins, avoiding a decrease in bonding strength caused by interfacial corrosion. For example, in a grinding operation with coolant, the CBN abrasive 3 is more resistant to hydrothermal erosion than diamond, and the bonding interface between the coating and the resin is more durable and reliable.

[0049] In this embodiment, the surface of the CBN abrasive 3 is subjected to acid etching (such as treatment with nitric acid and hydrochloric acid) or ultrasonic cleaning. After treatment, the surface of the CBN abrasive 3 has a microscopic uneven structure, forming a stronger mechanical interlock with the metal coating 4. For example, the nickel coating can penetrate into the nanoscale pores on the surface of the CBN abrasive 3 to form a "pinning effect".

[0050] In this embodiment, a thin layer of copper (catalytic activation) is pre-plated on the surface of the CBN abrasive 3. After pre-plating a thin layer of copper, the wettability of the surface of the CBN abrasive 3 with the subsequent nickel coating is improved, avoiding coating peeling caused by low surface energy, similar to the principle of a "primer" enhancing the adhesion of the coating.

[0051] In other embodiments, the abrasive is diamond. Diamond is known as the hardest material in nature (Mohs hardness grade 10, microhardness up to 10000 HV), more than twice as high as the CBN abrasive 3 (about 5000 HV). This enables it to maintain a sharp cutting edge for 3 - 5 times longer during the processing of high-hardness non-metallic materials (such as ceramics, glass, cemented carbide) as the tip of the abrasive grains is not easily worn. For example, when grinding silicon carbide ceramics, the material removal rate (MRR) of the diamond grinding wheel can reach 2 - 3 times that of the CBN abrasive 3 grinding wheel, significantly improving the processing efficiency.

[0052] In this embodiment, the particle size of the CBN abrasive 3 is 140 / 170 (i.e., the particle size range is 88 - 106 μm), which is a medium-fine particle size. The fine cutting edges can reduce the single-grinding depth and the impact force borne by a single particle, thereby reducing the risk of interface detachment between the abrasive and the metal coating 4 due to overload.

[0053] Fine-grained abrasives can form a smoother machining surface, avoiding the propagation of resin microcracks caused by local stress concentration during coarse-grained grinding, indirectly protecting the integrity of the bonding interface.

[0054] The CBN abrasive 3 with a particle size of 140 / 170 has a smaller particle diameter, and the metal coating 4 can form a "thin and uniform" coating layer. The thin coating reduces material consumption on the one hand and reduces the problem of "particle center of gravity shift" caused by an overly thick coating on the other hand (for coarse-grained abrasives, an overly thick coating is prone to falling off due to an increase in rotational centrifugal force caused by the outward shift of the center of gravity).

[0055] Fine-grained particles are more densely distributed on the nickel foil paper 5, and the current field distribution during secondary electroplating is more uniform (the particle spacing is small, and the electric field shielding effect is weakened), avoiding insufficient particle anchoring force caused by overly thin plating in some local areas.

[0056] The pores formed after the accumulation of CBN abrasive 3 particles with a size of 140 / 170 can form a cross-scale interlocking structure with the molecular chain size (nanoscale) after the curing of epoxy resin. The resin can penetrate into the particle gaps and microscopic pores of the plating layer to form a "resin-metal-abrasive" three-level anchoring (similar to the synergistic effect of steel bars and aggregates in concrete), enhancing the bonding strength.

[0057] In other embodiments, there can be coarser particle sizes (such as 80 / 100) or finer particle sizes (such as 325 / 400). The particle size of the abrasive needs to be adjusted according to the actual situation.

[0058] In this embodiment, the depth of the abrasive penetrating into the resin is one-third of the abrasive diameter. There are micron-scale grooves on the surface of the metal plating layer 4 (naturally formed by the electroplating process, with a roughness of Ra1.6 - 3.2 μm). When the depth of the abrasive embedded in the resin is one-third of the abrasive diameter, the resin can penetrate into the plating grooves to form a "mechanical mortise and tenon structure".

[0059] Nanoscale pits will be formed on the surface of CBN abrasive 3 particles after acid etching treatment before electroplating (and still exist after electroplating). After being embedded in the resin, "nanoscale barbs" are formed, enhancing the adsorption energy of the interface through van der Waals forces.

[0060] In this embodiment, by controlling the length of the lever arm (exposed height) and the holding volume, the grinding load is evenly distributed on the "abrasive-plating-resin" interface, avoiding stress concentration.

[0061] In this embodiment, the resin is organic epoxy resin 2. The molecular structure of organic epoxy resin 2 contains a large number of polar groups (such as hydroxyl groups, ether bonds), which can form chemical bonds (such as hydrogen bonds, covalent bonds) with the surface of the grinding wheel base 1 and CBN abrasive 3, significantly enhancing the interfacial bonding force and effectively preventing the abrasive from falling off during high-speed grinding.

[0062] After curing, the epoxy resin forms a three-dimensional network structure, which can resist the erosion of acid and alkali components in grinding fluids (such as oily cutting fluids, aqueous coolants), avoiding the loosening of abrasives caused by resin degradation.

[0063] The shrinkage rate of the epoxy resin during curing is only 1% - 2%, ensuring the stable dimensional accuracy of the grinding wheel after molding. It can avoid uneven distribution of abrasives or cracking of the bonding layer caused by shrinkage deformation.

[0064] The molecular chain of epoxy resin has a certain flexibility and combines rigidity and toughness after curing. When the grinding wheel is suddenly impacted (such as eccentric grinding of the workpiece), the resin can absorb energy through the deformation of the molecular chain, reducing the impact force directly borne by the abrasive grains and reducing the risk of abrasive grain breakage or detachment.

[0065] Epoxy resin has a low thermal conductivity and can form a certain heat insulation layer during the grinding process, reducing the transfer of grinding heat to the substrate and avoiding the softening failure of the resin caused by local overheating. At the same time, its thermal expansion coefficient has a high matching degree with that of CBN abrasive grains 3, which can reduce the risk of interface cracking caused by thermal stress difference.

[0066] In this embodiment, the nickel plating surface is subjected to weak corrosion treatment after electroplating. Polar groups (such as NiO x ) will be formed on the nickel plating surface, which have hydrogen bond interactions with the hydroxyl groups (-OH) and ether bonds (-O-) in the organic epoxy resin 2, significantly improving the interfacial wettability between the metal plating 4 and the resin.

[0067] Crankshaft grinding case (electroplated abrasive grain size 120 / 140)

[0068] Case 1: Machining of the ceramic coating on the engine block A certain automotive parts enterprise uses the CBN grinding wheel prepared by this process for precision grinding of the ceramic coating on the engine block: Process parameters: The grinding wheel substrate 1 is made of aluminum alloy, the adhesive layer thickness is 20 μm, the molding temperature is 150 °C, and the pressure is 15 MPa.

[0069] Achievement: The grinding efficiency is increased by 40%, the surface roughness Ra ≤ 0.2 μm, and there is no insulation failure problem caused by electroplating solution penetration.

[0070] Case 2: Crankshaft grinding An ultra-hard material electroplated grinding wheel (such as CBN / diamond composite abrasive) is used to machine automotive crankshafts.

[0071] Preparation method: Electroplate the rough grinding (CBN) and fine grinding (diamond) abrasive grains step by step, and realize functional zoning through shielding technology.

[0072] Effect: The service life of the grinding wheel is extended by 50%, and the grinding accuracy meets the micron-level tolerance requirements.

Claims

1. A preparation method of a new type of electroplated grinding wheel, characterized in that, It includes the following steps: Step 1: Electroplate a metal coating on the surface layer of the abrasive; Step 2: Electroplate the electroplated abrasive on a nickel foil paper; Step 3: Coat the resin on the grinding wheel base, and then paste the nickel foil paper around the grinding wheel base on the organic epoxy resin; Step 4: Cure the nickel foil paper on the resin through a molding process to form a dense bond; Step 5: Remove the excess resin after molding.

2. The novel electroplated grinding wheel preparation method according to claim 1, wherein The abrasive is CBN abrasive.

3. The method for preparing a novel electroplated grinding wheel according to claim 1, wherein, The abrasive is diamond.

4. The method for preparing a novel electroplated grinding wheel according to claim 2, wherein The particle size of the CBN abrasive is 140 / 170.

5. The method for preparing a novel electroplated grinding wheel according to claim 1, wherein, The depth of the abrasive penetrating into the resin is one-third of the diameter of the abrasive.

6. The method for preparing a novel electroplated grinding wheel according to claim 1, characterized in that, The thickness of the nickel foil paper is 0.05 mm.

7. The method for preparing a novel electroplated grinding wheel according to claim 1, characterized in that, The resin is organic epoxy resin.

8. The method for preparing a novel electroplated grinding wheel according to claim 1, characterized in that, The diameter of the grinding wheel base is 100 mm.

9. The method for preparing a novel electroplated grinding wheel according to claim 1, wherein In the molding process, the temperature is 100 - 200 °C and the pressure is 5 - 20 MPa.

10. The novel electroplated grinding wheel preparation method according to claim 2, wherein The metal coating is a nickel coating.

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