Water-based high-lubrication cutting fluid and preparation method thereof

Abstract

The invention discloses a water-based high-lubrication cutting fluid and a preparation method thereof, and relates to the field of metal working fluids, the water-based high-lubrication cutting fluid comprises the following components by mass: 35-70% of deionized water, 5-15% of a lubricant, 5-10% of an extreme pressure anti-wear agent, 2-7% of an antirust agent, 3-8% of a bactericide, 4-8% of an emulsifier, 8-20% of a pH regulator, and 0.1% of an antifoaming agent; the bactericide is a mixture of dimorpholine methane and s-triazine. Through the synergistic effect of the lubricant and the anti-wear reagent at extreme pressure, the water-based cutting fluid has high lubricating property, and can effectively lubricate and reduce frictional wear even if metal materials with different processing difficulties are processed. In addition, an antirust agent is introduced into the water-based high-lubricity cutting fluid, and a mixture of dimorpholine methane and s-triazine is selected as a bactericide, so that the water-based high-lubricity cutting fluid becomes a multifunctional composite system integrating efficient lubrication, extreme pressure wear resistance, long-acting corrosion resistance and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of metalworking fluids, and more particularly to a water-based high-lubricity cutting fluid and its preparation method. Background Technology

[0002] Water-based cutting fluids, widely used in modern machining, are renowned for their superior cooling performance, economy, and environmental safety. By evaporating large amounts of water, they remove cutting heat, effectively reducing the temperature of the machining area, thereby minimizing workpiece thermal deformation, improving machining accuracy, and making them suitable for high-speed machining applications. Furthermore, compared to traditional oil-based products, water-based cutting fluids are less flammable, produce less smoke in the working environment, and are more operator-friendly.

[0003] However, despite the significant advantages of water-based cutting fluids, their application generally faces a series of technical challenges. For example, water's lubricity is far lower than that of oil, easily leading to rapid tool wear and poor workpiece surface finish when machining difficult-to-machine materials such as high-strength steel, titanium alloys, and high-temperature alloys. Under high-pressure, high-temperature boundary lubrication conditions, the poor extreme-pressure anti-wear performance of water-based cutting fluids can cause direct contact between the workpiece and the tool, resulting in "sintering" or "built-up edge." Furthermore, water provides a breeding ground for microorganisms (bacteria, fungi), making water-based cutting fluids prone to spoilage and deterioration, resulting in short service life and frequent replacements, increasing costs and environmental pressure. Moreover, water itself is a source of metal corrosion; therefore, water-based cutting fluids are insufficient in preventing rust on machine tools and workpieces. Additionally, water-based cutting fluids often contain harmful components such as sodium nitrite and chlorine-based extreme-pressure agents, posing environmental and health problems. Therefore, it is necessary to develop a water-based cutting fluid suitable for difficult-to-machine metal materials, with good lubricity, excellent extreme-pressure anti-wear properties, effective rust prevention, long service life, and environmental friendliness.

[0004] It is evident that existing technologies still need improvement and enhancement. Summary of the Invention

[0005] The purpose of this invention is to provide a water-based high-lubricity cutting fluid and its preparation method, aiming to improve the overall performance of water-based cutting fluids.

[0006] The first aspect of this invention provides a water-based high-lubricity cutting fluid, comprising the following components by mass percentage: 35-70% deionized water, 5-15% lubricant, 5-10% extreme pressure anti-wear agent, 2-7% rust inhibitor, 3-8% bactericide, 4-8% emulsifier, 8-20% pH adjuster, and 0.1% defoamer; wherein the bactericide is a mixture of bismorpholine methane and triazine. The water-based high-lubricity cutting fluid wherein the mass ratio of bismorpholine methane and triazine is 2:1.

[0007] The water-based high-lubricity cutting fluid, wherein the lubricant is a mixture of modified vegetable oil and high-performance esters; the modified vegetable oil is at least one of epoxidized soybean oil, oxidized rapeseed oil, and hydrogenated palm oil; and the high-performance esters are at least one of fatty acid methyl esters, methyl oleate, tetrameric castor oil ester, pentaerythritol ester, trimethylolpropane oleate, and isooctyl oleate.

[0008] The water-based high-lubricity cutting fluid wherein the extreme pressure anti-wear agent is a mixture of sulfur-based extreme pressure anti-wear agent, phosphorus-based extreme pressure anti-wear agent and boron-based extreme pressure anti-wear agent.

[0009] The water-based high-lubricity cutting fluid, wherein the sulfur-based extreme pressure anti-wear agent is a sulfurized fatty acid ester; the phosphorus-based extreme pressure anti-wear agent is at least one of tricresyl phosphate, di-n-butyl phosphite, oleyl alcohol polyether phosphate, and alcohol ether phosphate; and the boron-based extreme pressure anti-wear agent is at least one of triethanolamine borate and diethanolamine borate.

[0010] The water-based high-lubricity cutting fluid, wherein the rust inhibitor is at least one of sebacic acid, tribasic acid, and dodecanoic acid.

[0011] The water-based high-lubricity cutting fluid, wherein the emulsifier is at least one of fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, Span 80, and Tween 80.

[0012] The water-based high-lubricity cutting fluid wherein the pH adjuster is at least one of ethanolamine, diethanolamine, triethanolamine, isopropanolamine, and diethylene glycolamine.

[0013] A second aspect of this invention provides a method for preparing a water-based high-lubricity cutting fluid, comprising the following steps: S1. Mix the lubricant, extreme pressure anti-wear agent and emulsifier, then heat and stir until completely dissolved and homogeneous to obtain the oil phase; S2. Mix deionized water, rust inhibitor and pH adjuster, and stir until the rust inhibitor and pH adjuster are completely dissolved to obtain the aqueous phase; S3. Under high-speed stirring, the oil phase is slowly added to the aqueous phase to form a uniform and stable semi-transparent to transparent microemulsion. S4. After high-speed stirring, once the temperature of the microemulsion drops below 40°C, add bactericide and defoamer, stir evenly, and then filter to obtain a water-based high-lubricity cutting fluid.

[0014] Furthermore, in step S1, the heating temperature is 50-60℃, and in step S3, the high-speed stirring time is 30 minutes.

[0015] The beneficial effects of this invention are: The first aspect of this invention provides a water-based high-lubricity cutting fluid. This fluid utilizes the synergistic effect of lubricants and extreme-pressure anti-wear agents to achieve a multi-layered, dynamically adaptive, multi-lubrication structure. This results in high lubricity, effectively lubricating and reducing friction and wear even when machining metal materials with varying processing difficulties. Furthermore, by introducing a rust inhibitor into the water-based high-lubricity cutting fluid and selecting a mixture of bismorpholine methane and triazine as a bactericide, this invention transforms the water-based high-lubricity cutting fluid into a multifunctional composite system integrating high-efficiency lubrication, extreme-pressure anti-wear, long-term corrosion protection, and environmental friendliness.

[0016] The second aspect of this invention provides a method for preparing a water-based high-lubricity cutting fluid. This method is simple to operate, has controllable conditions, and can be adapted to the needs of industrial production. Heating promotes the full and uniform dissolution of the lubricant, extreme pressure anti-wear agent, and emulsifier, ensuring the dispersibility of the oil-based functional components. Dissolving the rust inhibitor and pH adjuster in the aqueous phase prevents them from reacting prematurely with the oil phase components and affecting performance. Subsequent slow addition of the oil phase to the aqueous phase under high-speed stirring utilizes shear force to promote full contact between the oil and water interfaces, forming a stable semi-transparent to transparent microemulsion in conjunction with the emulsifier's action. This avoids emulsion stratification and instability problems caused by improper mixing. Adding the bactericide and defoamer after the microemulsion has cooled to below 40°C prevents the bactericide's activity from being destroyed by high temperatures and avoids the defoamer's inactivation or the generation of additional foam due to high temperatures. Finally, filtration removes any impurities that may be present in the system, ensuring the purity and stability of the cutting fluid during use. Attached Figure Description

[0017] Figure 1 This is a photograph of the water-based high-lubricity cutting fluid provided by this invention.

[0018] Figure 2 This is a flowchart of the preparation method of the water-based high-lubricity cutting fluid provided by the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1As shown, the first aspect of the present invention provides a water-based high-lubricity cutting fluid, comprising the following components by mass percentage: 35-70% deionized water, 5-15% lubricant, 5-10% extreme pressure anti-wear agent, 2-7% rust inhibitor, 3-8% bactericide, 4-8% emulsifier, 8-20% pH adjuster, and 0.1% defoamer; wherein the bactericide is a mixture of bismorpholine methane and triazine. Bactericides are key functional additives used in water-based cutting fluids. During the circulation process, cutting fluids are susceptible to attack by bacteria, fungi, and other microorganisms, leading to emulsion decomposition and performance failure. At this point, bactericides play a crucial protective role, effectively killing and inhibiting the reproduction of microorganisms by disrupting their cell structure or inhibiting their metabolism. Based on this, this invention uses a combination of bismorpholine methane and triazine as a bactericide. Triazine can rapidly penetrate the cell walls of microorganisms, quickly suppressing their initial numbers; while bismorpholine methane establishes a dynamic balance in the water-based cutting fluid system, acting as a formaldehyde slow-release reservoir to provide long-lasting and fundamental antibacterial protection. The perfect synergy between bismorpholine methane and triazine in terms of antibacterial properties and time-dependent effects not only covers a wide range of microorganisms but also significantly delays the development of microbial resistance, achieving a synergistic broad-spectrum and long-lasting bactericidal effect. This extends the service life of the water-based cutting fluid, reducing the frequency of replacement and avoiding increased environmental pressure and operating costs.

[0021] Of the above components, deionized water serves as the basic carrier and solvent for water-based cutting fluids. The lubricants, emulsifiers, and rust inhibitors all need to be dissolved in water to achieve uniform dispersion and function. Furthermore, deionized water helps oily components form stable emulsions through emulsifiers and completely dissolves synthetic components into a transparent solution, ensuring consistent composition and performance throughout the cutting fluid. In addition, deionized water provides excellent cooling through convection heat transfer and evaporation heat absorption. Lubricants, through polar molecular adsorption, form a lubricating film on the metal surface, reducing friction and wear, thus addressing the insufficient lubrication performance of water-based cutting fluids.

[0022] When machining enters a high-speed, heavy-load state, high temperature and pressure are generated, which can cause the physical adsorption film formed by the lubricant to rupture and fail. Extreme pressure anti-wear agents can chemically react with the metal surface at high temperatures to form a robust chemical reaction film, thereby solving the problem of lubrication failure of water-based cutting fluids caused by the rupture of the physical adsorption film.

[0023] Of the above components, the rust inhibitor forms a hydrophobic protective film on the metal surface, preventing moisture and oxygen from contacting the metal and avoiding oxidation reactions that cause rust on the workpiece and machine tool surfaces. The emulsifier reduces the surface tension at the oil-water interface, allowing the oily components to form a stable emulsion in the water, ensuring consistent composition and performance throughout the cutting fluid. Adding a pH adjuster to the water-based cutting fluid maintains its pH within a suitable alkaline range, enhancing its rust prevention and antibacterial properties. It also prevents stratification and demulsification due to abnormal pH, ensuring the continued effectiveness of its core functions such as lubrication and cooling. The defoamer quickly eliminates and inhibits foam generated during the circulation of the water-based cutting fluid, preventing foam from isolating the tool and workpiece, avoiding leakage and environmental pollution, without weakening the cooling and lubrication effects, and without shortening tool life or reducing machining quality.

[0024] As can be seen, this invention, through the synergistic effect of lubricants and extreme pressure anti-wear agents, enables water-based cutting fluids to possess high lubrication performance, effectively lubricating and reducing friction and wear even when machining metal materials with varying processing difficulties. Furthermore, by introducing rust inhibitors into the water-based high-lubricity cutting fluid and selecting a mixture of bismorpholine methane and triazine as a bactericide, this invention transforms the water-based high-lubricity cutting fluid into a multifunctional composite system integrating high-efficiency lubrication, extreme pressure anti-wear, long-term corrosion protection, and environmental friendliness.

[0025] In an optional embodiment, bismorpholine methane and triazine are compounded in a mass ratio of 2:1 to achieve broad-spectrum, rapid bactericidal and long-lasting bacteriostatic effects, thereby effectively extending the service life of the cutting fluid.

[0026] In an optional embodiment, the lubricant is a mixture of modified vegetable oil and high-performance esters, enabling all-around lubrication from low-speed, light-load to high-speed, heavy-load applications. Compared to traditional polyether and mineral oil lubricants, the lubricant provided by this invention has long-chain molecules, resulting in stronger oil film strength and adsorption capacity, thereby significantly improving basic lubrication performance, and is also environmentally friendly and renewable.

[0027] Specifically, the modified vegetable oil is at least one of epoxidized soybean oil, oxidized rapeseed oil, and hydrogenated palm oil; the high-performance esters are at least one of fatty acid methyl ester, methyl oleate, tetrameric castor oil ester, pentaerythritol ester, trimethylolpropane oleate, and isooctyl oleate.

[0028] In an optional embodiment, the extreme pressure anti-wear agent is a mixture of sulfur-based, phosphorus-based, and boron-based extreme pressure anti-wear agents. The extreme pressure anti-wear agent of this invention employs a sulfur-phosphorus-boron composite system, which can function in different temperature ranges to form complete extreme pressure protection.

[0029] Specifically, the sulfur-based extreme pressure anti-wear agent is a sulfurized fatty acid ester; the phosphorus-based extreme pressure anti-wear agent is at least one selected from tricresyl phosphate, di-n-butyl phosphite, oleyl alcohol polyether phosphate, and alcohol ether phosphate; and the boron-based extreme pressure anti-wear agent is at least one selected from triethanolamine borate and diethanolamine borate. This invention discovers that boron-based extreme pressure anti-wear agents not only provide extreme pressure anti-wear effects but also possess certain antibacterial capabilities, helping to reduce the amount of bactericide used and further extending the service life of the working fluid. Furthermore, the sulfur-phosphorus-boron composite system of extreme pressure anti-wear agents used in this invention does not contain harmful substances such as sodium nitrite and chlorine-based extreme pressure anti-wear agents, making it environmentally friendly.

[0030] In terms of lubrication and extreme pressure anti-wear, the modified vegetable oil and high-performance ester composite lubrication system and the sulfur-phosphorus-boron composite extreme pressure system of this invention can produce a synergistic effect. During the lubrication process, the composite lubrication system first relies on the strong polar functional groups of the high-performance ester and modified vegetable oil to form a strong physical adsorption film on the metal surface. Due to the differences in molecular structure, polarity, and spatial configuration between the high-performance ester and modified vegetable oil, they can achieve a tighter and more optimized co-arrangement at the friction interface, thereby forming a denser and stronger composite adsorption film. This composite adsorption film has excellent spreadability and low friction characteristics, and can effectively reduce the coefficient of friction and cutting temperature under boundary lubrication conditions, thereby ensuring the surface quality of the workpiece and delaying tool wear. When the working conditions become extreme, and the local high temperature and pressure cause the physical adsorption film to face the risk of rupture, the sulfur-phosphorus-boron composite extreme pressure system is activated and plays a key chemical protective role. Among them, phosphorus-based extreme pressure anti-wear agents preferentially react to form a phosphate repair film with plastic flow characteristics; while sulfur-based extreme pressure anti-wear agents form a layered sulfide solid lubricating film at higher temperatures; and boron-based extreme pressure anti-wear agents generate a boron oxide glassy composite film with both high hardness and self-healing properties. These three extreme pressure anti-wear agents, containing sulfur, phosphorus, and boron respectively, form a temperature relay and functional complementarity in their extreme pressure anti-wear effects, thus constructing a multi-layered, wide-temperature-range dynamically adaptive protective structure covering the entire friction process from low to high temperatures.

[0031] In an optional embodiment, the rust inhibitor is at least one of sebacic acid, tricarboxylic acid, and dodecanoic acid. These rust inhibitors have polar groups that can firmly adhere to the metal surface, while the non-polar groups face outwards, forming a hydrophobic protective barrier that prevents moisture and oxygen from contacting each other.

[0032] In an optional embodiment, the emulsifier is at least one selected from fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, Span 80, and Tween 80. The emulsifiers described above can reduce the surface tension at the oil-water interface, allowing the oily components to form a stable emulsion in water, thus ensuring consistent composition and performance throughout the cutting fluid.

[0033] In an optional embodiment, the pH adjuster is at least one selected from ethanolamine, diethanolamine, triethanolamine, isopropanolamine, and diethylene glycolamine. The pH value of a water-based cutting fluid directly affects its rust-preventive performance, system stability, and antibacterial ability. Typically, it requires the addition of organic alkalis to adjust and maintain the pH value within a suitable alkaline range. In this invention, the pH adjuster employs an organic amine composite system, eliminating strong alkalinity and irritating inorganic alkalis. It provides a stable alkali reserve while also offering rust prevention and emulsification assistance for the water-based cutting fluid.

[0034] In optional embodiments, the defoamer is at least one of defoamer 1875, defoamer 575, defoamer 1267, defoamer 970, and defoamer 980. These defoamers, through their extremely low surface tension, can effectively disrupt the stability of the foam film, causing the foam to coalesce and rapidly rupture, thereby ensuring the stable performance of the water-based cutting fluid and playing a crucial role in maintaining efficient and continuous machining processes.

[0035] like Figure 2 As shown, a second aspect of the present invention provides a method for preparing a water-based high-lubricity cutting fluid, which includes the following steps: S1. Mix the lubricant, extreme pressure anti-wear agent and emulsifier, then heat and stir until completely dissolved and homogeneous to obtain the oil phase; S2. Mix deionized water, rust inhibitor and pH adjuster, and stir until the rust inhibitor and pH adjuster are completely dissolved to obtain the aqueous phase; S3. Under high-speed stirring, the oil phase is slowly added to the aqueous phase to form a uniform and stable semi-transparent to transparent microemulsion. S4. After high-speed stirring, once the temperature of the microemulsion drops below 40°C, add bactericide and defoamer, stir evenly, and then filter to obtain a water-based high-lubricity cutting fluid.

[0036] The preparation method of the water-based high-lubricity cutting fluid provided by this invention is simple to operate, with controllable conditions, and can be adapted to the needs of industrial production. Heating promotes the full and uniform dissolution of the lubricant, extreme pressure anti-wear agent, and emulsifier, ensuring the dispersibility of the oil-based functional components. Dissolving the rust inhibitor and pH adjuster in the aqueous phase prevents premature reaction with the oil phase components, thus avoiding performance degradation. Subsequent slow addition of the oil phase to the aqueous phase under high-speed stirring utilizes shear force to promote full contact between the oil and water interfaces, forming a stable semi-transparent to transparent microemulsion in conjunction with the emulsifier's action. This avoids emulsion stratification and instability caused by improper mixing. Adding the bactericide and defoamer after the microemulsion has cooled to below 40°C prevents the bactericide's activity from being destroyed by high temperatures and avoids the defoamer's inactivation or the generation of additional foam due to high temperatures. Finally, filtration removes any impurities that may be present in the system, ensuring the purity and stability of the cutting fluid during use.

[0037] Furthermore, in step S1, the heating temperature is 50–60°C. This promotes the rapid dissolution of lubricants, extreme pressure anti-wear agents, and emulsifiers, preventing insufficient dissolution and uneven mixing due to excessively low temperatures. Simultaneously, it prevents excessively high temperatures from damaging the molecular structure of modified vegetable oils and high-performance esters, ensuring their lubricating performance does not decline. In step S3, the high-speed stirring time is 30 minutes. This allows the oil phase to be fully dispersed in the aqueous phase through continuous shear force, forming a uniform and stable microemulsion in conjunction with the emulsifier. This avoids oil-water separation and emulsion instability caused by insufficient stirring time, while also preventing energy waste or excessive shearing that could damage the emulsion structure.

[0038] The following examples and comparative examples further illustrate the present invention. The sources of the raw materials used in the following examples and comparative examples are as follows: High-performance esters: Pentaerythritol esters (Jiaxing Zhongcheng Environmental Protection Technology Co., Ltd.); Modified vegetable oil: Oxidized rapeseed oil (Luoyang Pacific United Petrochemical Co., Ltd.); Phosphorus-based extreme pressure anti-wear agent: Tricresol phosphate (Shandong Shengcang Chemical Technology Co., Ltd.); Sulfur-based extreme pressure anti-wear agent: sulfurized fatty acid ester (Smin Oil & Chemical Co., Ltd.); Boron-based extreme pressure anti-wear agent: Triethanolamine borate (Dexu New Materials Co., Ltd.); Emulsifier: Fatty alcohol polyoxyethylene ether (Tianjin Haoruisen Chemical Trading Co., Ltd.); Emulsifier: Span 80 (Shaxian Licheng Chemical Co., Ltd.); Bactericide: Bismorpholine methane (MBM) (Shanghai Milin Chemical Co., Ltd.); Bactericide: Triazine (BK) (Shanghai Milin Chemical Co., Ltd.); Rust inhibitor: Tribasic acid (Tianjin Haoruisen Chemical Trading Co., Ltd.); pH adjuster: Triethanolamine (Dow Chemical Company Limited); pH adjuster: Diethanolamine (Tianjin Zhonghe Shengteng Chemical Co., Ltd.); Defoamer 1875 (Mengqingxin Additives Trading Shanghai Co., Ltd.)

[0039] Example 1 This embodiment provides a water-based (high lubrication) cutting fluid, comprising the following components by mass percentage: 5% pentaerythritol ester (high-performance ester), 5% oxidized rapeseed oil (modified vegetable oil), 2% tricresyl phosphate (phosphorus-based extreme pressure anti-wear agent), 1.5% sulfurized fatty acid ester (sulfur-based extreme pressure anti-wear agent), 3% triethanolamine borate ester (boron-based extreme pressure anti-wear agent), 4% fatty alcohol polyoxyethylene ether (emulsifier), 3% Span 80 (emulsifier), 3% bismorpholine methane (bactericide), 1.5% triazine (bactericide), 3% tribasic acid (rust inhibitor), 15% triethanolamine (pH adjuster), 4% diethanolamine (pH adjuster), 0.1% defoamer 1875, and the balance being deionized water.

[0040] This embodiment also provides a method for preparing a water-based (high lubrication) cutting fluid, including the following steps: S1. Mix the lubricant, extreme pressure anti-wear agent and emulsifier, then heat and stir until completely dissolved and homogeneous to obtain the oil phase; S2. Mix deionized water, rust inhibitor and pH adjuster, and stir until the rust inhibitor and pH adjuster are completely dissolved to obtain the aqueous phase; S3. Under high-speed stirring, the oil phase is slowly added to the aqueous phase to form a uniform and stable semi-transparent to transparent microemulsion. S4. After high-speed stirring, once the temperature of the microemulsion drops below 40°C, add bactericide and defoamer, stir evenly, and then filter to obtain a water-based high-lubricity cutting fluid.

[0041] In step S1, the heating temperature is 60℃, and in step S3, the high-speed stirring time is 30min.

[0042] The components of the water-based cutting fluids provided in Examples 2 and Comparative Examples 1-9 are shown in Tables 1 and 2 below. The preparation methods of the water-based cutting fluids provided in Examples 2 and Comparative Examples 1-9 are the same as those of the water-based (high lubrication) cutting fluid provided in Example 1.

[0043] Table 1

[0044] Table 2

[0045] The lubrication performance of the water-based cutting fluids provided in Example 1 and Comparative Examples 1 to 5 was tested. The test results are shown in Table 3 below. The test object was a 10% (w / w) diluted water-based cutting fluid (diluted with deionized water). The tapping torque values ​​of TC4 titanium alloy, GH4169 high-temperature alloy, and 304 stainless steel were tested using a microtap TTT tapping torque tester. The tapping torque test conditions were: cutting and tapping, speed 350 r / min, tapping depth 10 mm, and tapping hole diameter 3.7 mm. The lower the average tapping torque value, the better the lubrication.

[0046] The extreme pressure lubrication performance test method for water-based cutting fluids is conducted using a four-ball friction tester according to the standard GB / T12583-1998. The tester model is Xiamen Tianji MS-10A.

[0047] Table 3

[0048] As shown in Table 3 above, the water-based cutting fluid provided in Example 1 had the lowest average torque value in the tapping torque test of the three difficult-to-machine metals (titanium alloy, high-temperature alloy, and 304 stainless steel), indicating that the water-based cutting fluid provided in Example 1 had the best lubrication performance. In contrast, the water-based cutting fluid provided in Comparative Example 4 showed a significant decrease in lubrication performance compared to the water-based cutting fluid in Example 1, with its average torque value being the highest in the tapping torque test of the three difficult-to-machine metals. This is because Comparative Example 4 used mineral oil (base oil 150N) as a lubricant; while Example 1 used a composite of modified vegetable oil and high-performance esters as a lubricant, which has a stronger polar adsorption capacity, resulting in better oil film strength during lubrication compared to mineral oil, and more effectively reducing frictional resistance. Comparative Example 5 used only high-performance esters as a lubricant, and the average tapping torque of the three difficult-to-machine metals decreased compared to Comparative Example 4, but was still lower than that of Example 1. This is because, compared to the solution that uses only high-performance esters for lubrication, Example 1 combines high-performance esters with vegetable oils. Due to the differences in molecular structure, polarity, and spatial configuration between the two, they can achieve a tighter and more optimized co-arrangement at the friction interface, thereby forming a denser and stronger composite adsorption film. This film can more effectively isolate the metal surface from contact and reduce friction.

[0049] Comparing the extreme pressure lubrication performance of water-based cutting fluids, it was found that the water-based lubricants provided in Comparative Examples 1 to 4 all had lower non-seize load (PB) values ​​compared to the water-based lubricant provided in Example 1. Furthermore, the sintering load (PD) value of Comparative Example 2 was also one level lower than that of Example 1. This is because Example 1 used an extreme pressure anti-wear agent with a sulfur-phosphorus-boron composite system. The phosphorus-based extreme pressure anti-wear agent first forms a soft repair film at the contact point (the friction contact surface between the tool and the workpiece) to prevent initial seize and severe wear. The boron-based extreme pressure anti-wear agent can simultaneously form a tough glassy film and, in synergy with the phosphorus-based repair film, jointly strengthen the first chemical reaction defense line after the adsorption film, thereby pushing the critical point (PB value) for seize to a higher level. The sulfur-based system can fully exert its effects under more extreme and harsh conditions, generating a layered iron sulfide film to prevent micro-welding (sintering) between friction pairs, thus improving the sintering load (PD) value.

[0050] The antibacterial and anti-rust properties of the water-based cutting fluids provided in Example 2 and Comparative Examples 6 to 9 were tested respectively. The test results are shown in Table 4 below. Specifically, for the antibacterial performance test, the test object was a 10% (w / w) dilution of the cutting fluid (diluted with deionized water). Before the test, 900 ml of the dilution was added to a 1 L beaker, and then 100 ml of bacterial inoculum and 10 g of iron filings, corn starch, casein, and other nutrients required by microorganisms were added and stirred evenly. The beaker was placed in a 30℃ constant temperature water bath and aerated. Aeration was carried out for 5 days and stopped for 2 days in each cycle, and sterile water was added to compensate for the loss caused by evaporation. The total bacterial count of the bacterial inoculum used in the experiment reached 10. 7 CFU / mL or higher, total fungal colony count reaching 10 3 CFU / mL or higher. On day 30 of the experiment, the total number of bacterial and fungal colonies in the sample was detected using a bacterial test strip; the lower the colony count, the stronger the antibacterial performance.

[0051] The rust-preventive performance of water-based cutting fluids was tested according to the standard JB / T 9189, specifically by testing the penetration point of cast iron chips. The experimental method was as follows: a clean filter paper was laid flat in a petri dish, and approximately 2 g of cast iron chips were spread on the filter paper. Then, approximately 2 g of diluted cutting fluid was evenly dripped onto the filter paper. After 2 hours, the presence of yellow cast iron chip rust spots on the filter paper was observed. The minimum concentration of cutting fluid required to achieve a complete absence of rust spots was defined as the penetration point of the cutting fluid. A lower penetration point concentration indicated better rust-preventive performance of the water-based cutting fluid.

[0052] Table 4

[0053] By comparing the fungal and bacterial colony counts of Example 2 with those of Comparative Examples 6 and 7 after antibacterial performance testing, it was found that the fungal colony counts of all three fell within the same range. The bacterial colony count was negatively correlated with the content of triethanolamine borate, indicating that triethanolamine borate has a synergistic bactericidal and bacteriostatic effect on water-based cutting fluids. However, the fungal and bacterial colony counts of Comparative Examples 8 and 9 were relatively high, indicating that the fluids were almost completely decomposed, suggesting that the antibacterial effect of adding bismorpholine methane or triazine alone to water-based cutting fluids is not ideal.

[0054] Comparing the rust-preventive performance of water-based cutting fluids, it was found that when Comparative Example 7 used a large amount of organic carboxylic acid (tricarboxylic acid) as a rust inhibitor, its rust-preventive effect was comparable to that of using the same amount of organic carboxylic acid in combination with triethanolamine borate (e.g., Example 2, Comparative Example 8, Comparative Example 9). This indicates that triethanolamine borate and organic carboxylic acid have a good synergistic effect in rust prevention. The addition of triethanolamine borate can reduce the amount of organic carboxylic acid, improve lubrication, and ensure effective rust prevention.

[0055] In summary, the water-based high-lubricity cutting fluid provided by this invention has the following advantages compared to existing water-based cutting fluids: (1) Good lubrication performance. When machining difficult materials, the water-based high lubrication cutting fluid provided by the present invention can effectively reduce friction, reduce tool wear and ensure the surface finish of the workpiece.

[0056] (2) Excellent extreme pressure anti-wear performance. Under high pressure and high temperature boundary lubrication conditions, the water-based high lubrication cutting fluid provided by the present invention can maintain reliable oil film strength, avoid direct contact between the workpiece and the tool, and inhibit the generation of "sintering" or "built-up edge".

[0057] (3) The water-based high-lubricity cutting fluid provided by the present invention has a long service life and can avoid frequent replacement, thus reducing the cost of cutting fluid use and environmental pressure.

[0058] (4) The water-based high-lubricity cutting fluid provided by the present invention uses organic carboxylic acid as a rust inhibitor. The organic carboxylic acid can work synergistically with boron-based extreme pressure anti-wear agent. The generated organic salt can form a dense protective film on the metal surface. While maintaining good lubricity, it provides excellent rust prevention performance and can effectively protect the machine tool and the workpiece during the processing.

[0059] (5) The water-based high-lubricity cutting fluid provided by the present invention is environmentally friendly and does not contain harmful components such as sodium nitrite and chlorine-based extreme pressure anti-wear agents.

[0060] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A water-based high-lubricity cutting fluid, characterized in that, The product comprises the following components by mass percentage: 35-70% deionized water, 5-15% lubricant, 5-10% extreme pressure anti-wear agent, 2-7% rust inhibitor, 3-8% bactericide, 4-8% emulsifier, 8-20% pH adjuster, and 0.1% defoamer; the bactericide is a mixture of bismorpholine methane and triazine.

2. The water-based high-lubricity cutting fluid according to claim 1, characterized in that, The mass ratio of the bismorpholine methane to the triazine is 2:

1.

3. The water-based high-lubricity cutting fluid according to claim 1, characterized in that, The lubricant is a mixture of modified vegetable oil and high-performance esters; the modified vegetable oil is at least one of epoxidized soybean oil, oxidized rapeseed oil, and hydrogenated palm oil; the high-performance esters are at least one of fatty acid methyl ester, methyl oleate, tetrameric castor oil ester, pentaerythritol ester, trimethylolpropane oleate, and isooctyl oleate.

4. The water-based high-lubricity cutting fluid according to claim 1, characterized in that, The extreme pressure anti-wear agent is a mixture of sulfur-based extreme pressure anti-wear agents, phosphorus-based extreme pressure anti-wear agents, and boron-based extreme pressure anti-wear agents.

5. The water-based high-lubricity cutting fluid according to claim 4, characterized in that, The sulfur-based extreme pressure anti-wear agent is a sulfurized fatty acid ester; the phosphorus-based extreme pressure anti-wear agent is at least one of tricresyl phosphate, di-n-butyl phosphite, oleyl alcohol polyether phosphate, and alcohol ether phosphate; the boron-based extreme pressure anti-wear agent is at least one of triethanolamine borate and diethanolamine borate.

6. The water-based high-lubricity cutting fluid according to claim 1, characterized in that, The rust inhibitor is at least one of sebacic acid, tricarboxylic acid, and dodecanoic acid.

7. The water-based high-lubricity cutting fluid according to claim 1, characterized in that, The emulsifier is at least one of fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, Span 80, and Tween 80.

8. The water-based high-lubricity cutting fluid according to claim 1, characterized in that, The pH adjuster is at least one of ethanolamine, diethanolamine, triethanolamine, isopropanolamine, and diethylene glycolamine.

9. A method for preparing a water-based high-lubricity cutting fluid, characterized in that, The preparation of the water-based high-lubricity cutting fluid as described in any one of claims 1-8 includes the following steps: S1. Mix the lubricant, extreme pressure anti-wear agent and emulsifier, then heat and stir until completely dissolved and homogeneous to obtain the oil phase; S2. Mix deionized water, rust inhibitor and pH adjuster, and stir until the rust inhibitor and pH adjuster are completely dissolved to obtain the aqueous phase; S3. Under high-speed stirring, the oil phase is slowly added to the aqueous phase to form a uniform and stable semi-transparent to transparent microemulsion. S4. After high-speed stirring, once the temperature of the microemulsion drops below 40°C, add bactericide and defoamer, stir evenly, and then filter to obtain a water-based high-lubricity cutting fluid.

10. The method for preparing the water-based high-lubricity cutting fluid according to claim 9, characterized in that, In step S1, the heating temperature is 50-60℃, and in step S3, the high-speed stirring time is 30 minutes.

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