Metal grinding fluid and method of making same

Abstract

The application relates to the technical field of grinding fluids for metal processing, and discloses a metal grinding fluid and a preparation method thereof. The metal grinding fluid is prepared from the following raw materials in percentage by mass: deionized water 60-70%, lubricant 5-15%, organic alkali 9-15%, antirust agent 5-10%, bactericide 2-5%, settling agent 0.1-0.5%, defoaming agent 0.2-0.3% and copper corrosion inhibitor 0.3-0.5%. The metal grinding fluid takes deionized water as a basic component and is compounded with lubricant, organic alkali, antirust agent, bactericide, settling agent, defoaming agent and copper corrosion inhibitor, so that the synthesized grinding fluid has excellent antirust performance, good cleaning and chip removal performance and good cooling performance. Moreover, the polyether ester and organic molybdenum are selected as the lubricant, the synergistic lubrication effect is realized, the friction-reducing and wear-resisting capacity of the grinding fluid is greatly improved compared with the lubricant used alone, and the metal grinding fluid can meet the grinding lubrication requirements of difficult-to-machine metals.

Description

Technical Field

[0001] This invention relates to the field of grinding fluid technology for metal processing, and in particular to a metal grinding fluid and its preparation method. Background Technology

[0002] Grinding is a machining method that removes excess material from a workpiece using abrasives and grinding wheels; it is a type of finishing process. Due to its high efficiency, high precision, and stringent surface quality requirements, grinding fluid is necessary in grinding operations.

[0003] In the field of machining, difficult-to-machine metals refer to metal materials whose chemical composition, metallographic structure, physical and mechanical properties make them difficult to process during cutting and grinding, resulting in low processing efficiency, rapid wear of tools / dies, and difficulty in obtaining high precision and excellent surface quality. The existing grinding fluids cannot meet the requirements of grinding difficult-to-machine metals. Specifically, the existing grinding fluids have the following shortcomings: (1) Insufficient lubrication performance. The oil film thickness formed by the existing grinding fluids is relatively thin, the lubrication continuity is poor, and the lubrication failure is easy to occur under extreme working conditions; (2) Insufficient rust prevention performance. The grinding fluid is prone to forming an uneven acidic oxide film during use, which will accelerate the corrosion of the processing machine and workpiece; (3) Poor cooling performance. The heat generated by the tool during operation cannot be carried away by the grinding fluid in time, which leads to tool overheating and a significant reduction in service life; (4) Poor cleaning and chip removal performance. The metal chips generated during grinding cannot be removed by the grinding fluid in time. The residual metal chips will affect the accuracy and quality of the processed surface. Therefore, it is necessary to develop a grinding fluid with good lubrication, excellent cooling, good cleaning and chip removal performance, and outstanding rust prevention performance so that the grinding fluid can meet the requirements of grinding difficult-to-machine metals. Summary of the Invention

[0004] The purpose of this invention is to provide a metal grinding fluid and its preparation method, aiming to solve the problem that existing metalworking grinding fluids are unsuitable for grinding difficult-to-machine metals due to poor cooling capacity, weak cleaning and chip removal capabilities, and insufficient lubrication performance.

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a metal grinding fluid, the raw materials for which, by mass percentage, are: 60-70% deionized water, 5-15% lubricant, 9-15% organic alkali, 5-10% rust inhibitor, 2-5% bactericide, 0.1-0.5% flocculant, 0.2-0.3% defoamer, and 0.3-0.5% copper corrosion inhibitor; wherein the lubricant is a mixture of polyether ester and organic molybdenum.

[0006] In the metal grinding fluid, the mass ratio of the polyether ester to the organic molybdenum is (0.8-1.2):1.

[0007] In the metal grinding fluid, the organic base is at least one of a specific amine CHO2O and N-methyldiethanolamine.

[0008] In the metal grinding fluid, the rust inhibitor is at least one of a monobasic acid and a tetrabasic acid.

[0009] In the metal grinding fluid, the monobasic acid is rust inhibitor NEUF685-2, and the tetrabasic acid rust inhibitor is rust inhibitor NEUF985.

[0010] In the metal grinding fluid, the copper corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, and benzotriazole.

[0011] In the metal grinding fluid, the settling agent is polyquaternary ammonium salt-2.

[0012] In the metal grinding fluid, the bactericide is at least one of bactericide M722, bactericide M789F, and isothiazolinone.

[0013] In the metal grinding fluid, the defoamer is defoamer 1875, defoamer 1880, or defoamer 1890.

[0014] A second aspect of the present invention provides a method for preparing a metal grinding fluid, which includes the following steps: S1. Mix deionized water and organic base, and stir until homogeneous and transparent; S2. Slowly add the rust inhibitor to the mixed solution obtained in step S1 and stir until it is homogeneous and transparent; S3. Add lubricant, bactericide, copper corrosion inhibitor and flocculant to the mixed solution obtained in step S2 in sequence, and stir until homogeneous and transparent; S4. Add defoamer to the mixed solution obtained in step S3, stir evenly to obtain the metal grinding fluid.

[0015] The beneficial effects of this invention are: The first aspect of this invention provides a metal grinding fluid, which uses deionized water as a base component and is compounded with lubricants, organic bases, rust inhibitors, bactericides, flocculants, defoamers, and copper corrosion inhibitors. This results in a grinding fluid with excellent rust prevention properties, superior cleaning and chip removal capabilities, and excellent cooling performance. Furthermore, by selecting polyether ester and organic molybdenum as lubricants, a synergistic lubrication effect is achieved. Compared to using a single lubricant, this significantly improves the friction reduction and anti-wear capabilities of the grinding fluid, enabling it to meet the grinding and lubrication requirements of difficult-to-machine metals.

[0016] The second aspect of this invention provides a method for preparing metal grinding fluid. The preparation method is simple, the quality is controllable, and it can quickly produce metal grinding fluid suitable for grinding difficult-to-machine metals, which is conducive to the large-scale, industrial, and market-oriented application of metal grinding fluid. Attached Figure Description

[0017] Figure 1 This is a physical image of the metal grinding fluid provided by the present invention.

[0018] Figure 2 This is a flowchart of the preparation method of the metal grinding 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 1 As shown, the first aspect of this invention provides a metal grinding fluid, the raw materials for which, by mass percentage, are: 60-70% deionized water, 5-15% lubricant, 9-15% organic alkali, 5-10% rust inhibitor, 2-5% bactericide, 0.1-0.5% flocculant, 0.2-0.3% defoamer, and 0.3-0.5% copper corrosion inhibitor. This technical solution, through the synergistic effect of the above raw materials, results in a grinding fluid with excellent lubrication and rust prevention properties, as well as superior cleaning and chip removal capabilities and excellent cooling performance, thus meeting the requirements for grinding difficult-to-machine metals.

[0021] Specifically, in the aforementioned raw materials for preparing metal grinding fluids, deionized water serves as the dispersion medium and cooling carrier. Firstly, it provides a stable and uniform dissolution and dispersion environment for various functional additives in the grinding fluid, ensuring its long-term stability. Secondly, water's high specific heat capacity enables efficient cooling, quickly removing the large amount of heat generated during grinding of difficult-to-machine metals, reducing the temperature of the workpiece and cutting tool, and preventing workpiece burns, deformation, and high-temperature failure of the lubricating film. Furthermore, deionized water contains no impurity ions, reducing electrochemical corrosion of metal workpieces and machine tool components, and synergistically enhancing the protective effect with rust inhibitors and corrosion inhibitors, ensuring the overall stability and reliability of the grinding fluid's performance.

[0022] Furthermore, in the aforementioned raw materials for preparing the metal grinding fluid, the lubricant can form a lubricating film on the metal surface, effectively isolating the friction pairs during grinding, significantly reducing direct friction and wear between metals, and simultaneously reducing heat generation during grinding. To further improve the lubrication performance of the grinding fluid and enable it to adapt to the high-temperature, high-pressure, and high-friction conditions of grinding difficult-to-machine metals, in a preferred embodiment, the lubricant is a mixture of polyether ester and organic molybdenum.

[0023] Polyether ester, through its polar functional groups, physically adsorbs onto the metal surface to form a physical adsorption film. This effectively isolates friction pairs during grinding, reducing direct contact and friction between metals at a physical level, thus providing basic lubrication for grinding. Furthermore, this adsorption film exhibits good stability and can continuously provide lubrication under normal machining conditions. Organic molybdenum decomposes under the high temperature and pressure conditions generated during grinding, releasing molybdenum disulfide or molybdenum trioxide, which reacts with the metal surface to form a layered solid lubricating film. This solid lubricating film is adaptable to the harsh conditions of grinding difficult-to-machine metals, compensating for the lubrication failure of the physical adsorption film under extreme conditions, allowing the metal grinding fluid to effectively reduce friction and resist wear even under extreme conditions. Therefore, the combination and uniform dissolution of polyether ester and organic molybdenum lubricants in the grinding fluid system achieves a synergistic lubrication effect. Compared to using a single lubricant, this significantly improves the friction-reducing and wear-resistant capabilities of the grinding fluid, meeting the lubrication requirements for grinding difficult-to-machine metals such as high-temperature alloys and high-strength steel.

[0024] To achieve synergistic lubrication, in a preferred embodiment, the mass ratio of polyether ester to organic molybdenum is (0.8–1.2):1. When the mass ratio of polyether ester to organic molybdenum is >1.2, the low proportion of organic molybdenum in the lubricant leads to insufficient molybdenum disulfide and molybdenum trioxide produced during grinding (especially high-speed grinding of difficult-to-machine metals) under high temperature and high pressure conditions. This results in an inability to form a complete and dense layered solid lubricating film on the metal surface, significantly weakening the lubrication effect under high temperature and high speed. When the mass ratio of polyether ester to organic molybdenum is <0.8, the low proportion of polyether ester in the lubricant leads to insufficient thickness and decreased density of the physically adsorbed film formed on the metal surface. This fails to effectively isolate the friction pairs during grinding, significantly reducing the basic lubrication effect under low load.

[0025] Furthermore, in the aforementioned raw materials for preparing metal grinding fluids, organic bases are primarily used to neutralize the acids generated under acidic reaction conditions, preventing abnormal drops in the system's pH value that could lead to metal corrosion and maintaining the stability of reactants and products. Secondly, in the acidic environment of the grinding fluid, the molecules of various organic additives (such as polyether esters and carboxylic acid rust inhibitors) lose protons and become negatively charged ions. Organic bases can neutralize these active negative ions in the grinding fluid, reforming structurally stable neutral compounds, thus preserving the original function of the grinding fluid. Moreover, organic bases can also react with rust inhibitors to generate organic salts, providing a basis for the formation of a passivation film on the metal surface.

[0026] To enable the metal grinding fluid to possess both rust-preventing and corrosion-preventing functions, in a preferred embodiment, the organic base is a mixture of a specific amine CHO20 and N-methyldiethanolamine. Specifically, N-methyldiethanolamine is a tertiary alcohol amine, which has mild alkalinity and strong buffering capacity, and low self-ionization, thus preventing a sudden increase in the pH value of the grinding fluid system. The specific amine CHO20 has a slightly higher alkalinity than N-methyldiethanolamine. When used in combination with N-methyldiethanolamine, it can stabilize the pH value of the grinding fluid within a reasonable range, thereby ensuring that the rust inhibitor fully forms a passivation film while preventing excessively high pH values ​​from corroding the metal.

[0027] In a preferred embodiment, the mass ratio of the specific amine CH020 to N-methyldiethanolamine is 1:(1-2.5). When the mass ratio of the specific amine CH020 to N-methyldiethanolamine is >1, the amount of specific amine CH020 used is too high, and the proportion of N-methyldiethanolamine in the organic base is insufficient, which will reduce the alkalinity of the grinding fluid. Furthermore, the rust inhibitor needs to be neutralized with the organic base to form a passivation film; when the proportion of the specific amine CH020 is too high, the passivation film formed by the reaction of the organic base and the rust inhibitor is loose, which will lead to an increase in the penetration point of cast iron chips and a decrease in the immersion corrosion level of the workpiece. When the mass ratio of the specific amine CH020 to N-methyldiethanolamine is <1 / 2.5, the proportion of N-methyldiethanolamine in the organic base is too high, which will form a thick alkaline adsorption layer on the metal surface, which will strongly compete with the lubricant for adsorption, resulting in a decrease in the lubrication performance of the grinding fluid.

[0028] Furthermore, in the aforementioned raw materials for preparing metal grinding fluid, the rust inhibitor can completely isolate the metal from corrosive media such as air and moisture in the atmosphere by forming a multi-layered dense passivation protective film on the metal surface, thereby reducing the chemical activity of the metal and slowing down the oxidation and corrosion rate of the metal.

[0029] To ensure the long-lasting rust prevention effect, in a preferred embodiment, the rust inhibitor is a mixture of monobasic acid and tetrabasic acid. Specifically, monobasic acid has a short molecular chain and fast film formation, enabling it to quickly form a basic passivation film on the metal surface, achieving immediate rust prevention without competing with the lubricant for adsorption. On the other hand, tetrabasic acid has a long molecular chain and strong chelating ability, enabling it to form a more resilient, temperature- and erosion-resistant cross-linked reinforced film on the outside of the basic passivation film. Therefore, it can guarantee long-lasting rust prevention and protection requirements under harsh grinding conditions.

[0030] In a preferred embodiment, the monocarboxylic acid is rust inhibitor NEUF685-2, the tetracarboxylic acid rust inhibitor is rust inhibitor NEUF985, and the mass ratio of rust inhibitor NEUF685-2 to rust inhibitor NEUF985 is 1:1. Specifically, rust inhibitor NEUF685-2 is a monocarboxylic acid rust inhibitor with a short molecular chain and few carboxyl sites. It can quickly neutralize the organic base in the grinding fluid to form a carboxylic acid alcohol amine salt, which is tightly adsorbed on the metal surface after grinding to form a passivation film, achieving immediate rust prevention. Moreover, the film is thin and does not compete with the lubricant for adsorption sites on the metal surface, avoiding competitive adsorption between lubrication and rust prevention, and ensuring the core lubrication performance of the grinding fluid. As a tetracarboxylic acid rust inhibitor, NEUF985 has a longer molecular chain and a stronger chelating ability with metal ions. It can react with organic bases to form cross-linked carboxylic acid alcohol amine salts, forming a thick passivation film on the metal surface that is tough, has high adhesion, and is resistant to temperature and erosion. This film can resist the medium and high temperatures during grinding of difficult-to-machine metals and the continuous erosion of grinding fluid, thus preventing the passivation film from cracking and falling off, achieving long-term rust prevention, and significantly extending the rust prevention cycle between workpiece processes. Secondly, the multi-carboxyl structure of rust inhibitor NEUF985 has excellent synergy with the alcohol amine organic bases in the grinding fluid. The passivation film formed can be tightly combined with the basic passivation film formed by NEUF685-2 to construct a double-layer composite protective structure, enhancing the overall rust prevention effect.

[0031] Furthermore, in the aforementioned raw materials for preparing metal grinding fluids, copper corrosion inhibitors can form a complex protective film through chemical adsorption and complexation reactions with copper ions, tightly covering the copper metal surface. This effectively isolates moisture, trace acidic products, oxygen, and other corrosive media in the grinding fluid, preventing oxidation, blackening, pitting, and intergranular corrosion of copper and copper alloys. This protects the surface integrity and operational accuracy of machine tool copper sleeves, copper pipes, copper workpiece connectors, and copper alloy substrates. Secondly, copper corrosion inhibitors exhibit selective adsorption for copper metal, forming a film only on the surface of copper and copper alloys. They do not adsorb onto the surfaces of carbon steel, stainless steel, high-temperature alloys, or other workpieces, avoiding competition for adsorption sites with rust inhibitors and lubricants in the grinding fluid. This prevents interference with the core lubrication and rust prevention functions of the grinding fluid. For example, the copper corrosion inhibitor can be at least one of benzotriazole, methylbenzotriazole, and benzotriazole.

[0032] Furthermore, in the aforementioned raw materials for preparing the metal grinding fluid, the flocculant first neutralizes the negatively charged micro-metal and abrasive particles in the water, eliminating the repulsive force between particles and allowing them to approach each other. Secondly, through the physical adsorption and bridging effect of its long molecular chains, the flocculant can aggregate dispersed fine particles into large flocs, allowing them to quickly settle to the bottom of the grinding equipment. This promptly removes debris from the processing area, preventing secondary friction on the grinding surface and ensuring the surface and dimensional accuracy of difficult-to-machine metals. For example, the flocculant can be polyquaternium-2.

[0033] Furthermore, in the aforementioned raw materials for preparing metal grinding fluids, the bactericide can inhibit and eliminate bacteria, fungi, and other microorganisms in water-based grinding fluids, preventing the excessive proliferation of microorganisms that decompose the core components such as organic alkalis, lubricants, and rust inhibitors in the grinding fluid, thus preventing the grinding fluid from deteriorating. Secondly, by inhibiting microbial activity, the bactericide can maintain the stability of each component in the grinding fluid, significantly extending its service life, reducing the frequency of grinding fluid replacement, and lowering raw material and maintenance costs in production. Moreover, microbial metabolism produces acidic products, which neutralize the organic alkalis in the grinding fluid, leading to a decrease in the system's pH value and an imbalance in alkali content, thereby causing problems such as metal corrosion and hindered lubrication film formation. The bactericide can block the microbial metabolic process, preventing the production of acidic byproducts, and fundamentally maintaining the stability of the grinding fluid's pH value, conductivity, and other physicochemical indicators, ensuring that the core functions of the grinding fluid, such as lubrication, rust prevention, and chip removal, are not diminished. For example, the bactericide may be at least one of bactericide M722, bactericide M789F, and isothiazolinone.

[0034] Furthermore, in the aforementioned raw materials for preparing the metal grinding fluid, the defoamer can quickly eliminate foam generated during processing and inhibit the continuous generation of foam, thus ensuring the stability of the grinding fluid system and the normal operation of the process. For example, the defoamer can be at least one of defoamer 1875, defoamer 1880, and defoamer 1890.

[0035] like Figure 2 As shown, a second aspect of the present invention provides a method for preparing a metal grinding fluid, which is used to prepare the metal grinding fluid as described above, comprising the following steps: S1. Mix deionized water and organic base, and stir at 40-45°C until homogeneous and transparent; S2. Slowly add the rust inhibitor to the mixed solution obtained in step S1 and stir until it is homogeneous and transparent; S3. Add lubricant, bactericide, copper corrosion inhibitor and flocculant to the mixed solution obtained in step S2 in sequence, and stir until homogeneous and transparent; S4. Add defoamer to the mixed solution obtained in step S3, stir evenly to obtain the metal grinding fluid.

[0036] The preparation method described is simple and the quality is controllable. It can quickly produce metal grinding fluid suitable for grinding difficult-to-machine metals, which is conducive to the large-scale, industrial, and market-oriented application of metal grinding fluid.

[0037] The following examples and comparative examples further illustrate the present invention. The sources of the raw materials used in the examples and comparative examples are as follows: Special amine CH020: Shandong Huling New Materials Co., Ltd.; N-Methyldiethanolamine (MDEA): Nantong Shenglun Chemical Technology Co., Ltd.; Rust inhibitor NEUF685-2: Nortech Biotechnology (Hefei) Co., Ltd.; Rust inhibitor NEUF985: Nortech Biotechnology (Hefei) Co., Ltd.; Lubricant polyether ester DS5740: Dongguan Hongli Chemical Technology Co., Ltd.; Organic molybdenum™-104 lubricant: Liaocheng Development Zone Chengsida Lubricant Co., Ltd.; Copper corrosion inhibitor (benzotriazole): Guangzhou Taili Chemical Co., Ltd.; Settling agent (polyquaternium-2): Runlin Chemical Materials (Suzhou) Co., Ltd.; Bactericide M722: Shanghai Wanhou Biotechnology Co., Ltd.; Defoamer 1875: Mengqingxin Additives Trading (Shanghai) Co., Ltd.

[0038] Example 1 This embodiment provides a metal grinding fluid, which, by mass percentage, comprises the following raw materials: 68% deionized water, 10% lubricant, 9% organic alkali, 10% rust inhibitor, 2% bactericide, 0.5% settling agent, 0.2% defoamer, and 0.3% copper corrosion inhibitor (benzotriazole).

[0039] As shown in Table 1, the lubricant is a mixture of polyether ester DS5740 and organic molybdenum TM-104. The organic base is a mixture of a specific amine CH020 and N-methyldiethanolamine. The rust inhibitor is a mixture of rust inhibitors NEUF685-2 and NEUF985.

[0040] This embodiment also provides a method for preparing metal grinding fluid, including the following steps: S1. Mix deionized water and organic base, and stir at 45°C until homogeneous and transparent; S2. Slowly add the rust inhibitor to the mixed solution obtained in step S1 and stir until it is homogeneous and transparent; S3. Add lubricant, bactericide, copper corrosion inhibitor and flocculant to the mixed solution obtained in step S2 in sequence, and stir until homogeneous and transparent; S4. Add defoamer to the mixed solution obtained in step S3, stir evenly to obtain the metal grinding fluid.

[0041] Example 2 This embodiment provides a metal grinding fluid, which, by mass percentage, comprises the following raw materials: 60% deionized water, 15% lubricant, 12% organic alkali, 10% rust inhibitor, 2.3% bactericide, 0.1% settling agent, 0.3% defoamer, and 0.3% copper corrosion inhibitor (benzotriazole).

[0042] As shown in Table 8, the lubricant is a mixture of polyether ester DS5740 and organic molybdenum TM-104. The organic base is a mixture of a specific amine CH020 and N-methyldiethanolamine. The rust inhibitor is a mixture of rust inhibitors NEUF685-2 and NEUF985.

[0043] This embodiment also provides a method for preparing metal grinding fluid, which is the same as the preparation method provided in Example 1.

[0044] Example 3 This embodiment provides a metal grinding fluid, which, by mass percentage, comprises the following raw materials: 65.7% deionized water, 8% lubricant, 15% organic alkali, 8% rust inhibitor, 2% bactericide, 0.5% settling agent, 0.3% defoamer, and 0.5% copper corrosion inhibitor (benzotriazole).

[0045] As shown in Table 10, the lubricant is a mixture of polyether ester DS5740 and organic molybdenum TM-104. The organic base is a mixture of a specific amine CH020 and N-methyldiethanolamine. The rust inhibitor is a mixture of rust inhibitors NEUF685-2 and NEUF985.

[0046] This embodiment also provides a method for preparing metal grinding fluid, which is the same as the preparation method provided in Example 1.

[0047] It should be noted that the preparation methods of the metal grinding fluids provided in the following comparative examples are the same as those of the metal grinding fluids provided in Example 1.

[0048] The raw material composition of the metal grinding fluids provided in Example 1, Comparative Example 1-1, Comparative Example 1-2, and Comparative Example 1-3 is shown in Table 1 below.

[0049] Table 1:

[0050] The pH value, conductivity, and alkalinity of the metal grinding fluids provided in Example 1, Comparative Example 1-1, Comparative Example 1-2, and Comparative Example 1-3 were tested respectively. The pH value was tested according to the standard GB / T 6144-2010 Fully Synthetic Cutting Fluids, and the conductivity was tested according to the standard GB / T 11007-2008 Conductivity Meter Test Method. The alkalinity was tested according to the standard SHT 0688-2000 Determination of Alkalinity Number of Petroleum Products and Lubricants (Potential Titration Method). The test results are shown in Table 2 below.

[0051] Table 2:

[0052] As can be seen from the test results in Table 2 above, the metal grinding fluid provided in Example 1 has moderate pH, conductivity, and alkalinity, indicating that the metal grinding fluid provided in Example 1 has a stable acid-base environment, reasonable ion concentration, and sufficient buffering capacity, enabling long-term stable use without corrosion, deterioration, or functional degradation. The metal grinding fluid provided in Comparative Example 1-1 has higher conductivity and alkalinity than that in Example 1. This is because the metal grinding fluid provided in Comparative Example 1-1 uses only N-methyldiethanolamine as the organic base. When the proportion of N-methyldiethanolamine in the organic base is too high, it will lead to a significant increase in the conductivity and alkalinity of the grinding fluid. The metal grinding fluid provided in Comparative Example 1-2 has higher pH and conductivity than that in Example 1, and a significantly lower alkalinity. This is because the metal grinding fluid provided in Comparative Example 1-2 uses only a slightly more alkaline special amine, CH020, as the organic base. The conductivity, alkali reserve value, and pH value of the metal grinding fluids provided in Comparative Examples 1-3 are all higher than those provided in Example 1. This is because the amount of organic alkali used in the metal grinding fluids provided in Comparative Examples 1-3 is significantly higher.

[0053] Furthermore, the raw material composition of the metal grinding fluids provided in Examples 1, 2-1, 2-2, 2-3, 2-4, and 2-5 is shown in Table 3 below.

[0054] Table 3:

[0055] The rust prevention and lubrication performance of the metal grinding fluids provided in Example 1, Comparative Examples 2-1 to 2-5 were tested respectively. The test for the penetration point of cast iron chips was conducted according to the standard "IP / 287 Standard for Rust Prevention Test of Iron Chips". The corrosion tests, such as immersion corrosion of HT300 cast iron, were conducted according to the standard "GB / T 6144-2010 Fully Synthetic Cutting Fluids". No-seize load P BThe test was conducted according to GB / T12583-1998 Determination of Extreme Pressure Properties of Lubricants (Four-Ball Method), and the test results are shown in Table 4 below.

[0056] Table 4:

[0057] As can be seen from the test results in Table 4 above, the rust-preventive and lubricating performance of the metal grinding fluid provided in Example 1 is superior to that of the other comparative examples. In Comparative Example 2-1, the amount of N-methyldiethanolamine (MDEA) was increased from 5% to 10%, and the total amount of organic alkali was increased from 9% to 14%, which increased the pH of the metal grinding fluid system. A high pH environment can promote the rapid neutralization of the tetrabasic acid rust inhibitor NEUF985 with the organic alkali to form a salt and a dense passivation film. Therefore, the pure tetrabasic acid rust inhibitor system can still achieve rust-preventive performance comparable to that of Example 1 in short-term static rust prevention tests. However, a high pH environment can also lead to excessive adsorption of the rust-preventive film, which competes strongly with the lubricant on the metal surface for adsorption, crowding out the effective adsorption sites of the lubricant film and reducing the formation efficiency of the polyether ester physical adsorption film and the organic molybdenum extreme pressure film. Therefore, the pH value is lower. B The value decreases significantly, and the lubrication performance deteriorates. The non-seize load P of the metal grinding fluid provided in Comparative Example 2-1 is significantly reduced. B The value is lower than that of Example 1 because the metal grinding fluid provided in Comparative Example 2-1 only used the tetrabasic acid rust inhibitor NEUF985. NEUF985 strongly competes with the lubricant for adsorption on the metal surface, preventing the lubricant from effectively forming a complete lubricating film and significantly reducing friction reduction and wear resistance. The rust-preventive performance of the metal grinding fluid provided in Comparative Example 2-2 is reduced because the amount of rust inhibitor NEUF685-2 in the metal grinding fluid provided in Comparative Example 2-2 is too high. NEUF685-2 quickly forms a passivation film on the metal surface, crowding out the binding sites of the tetrabasic acid rust inhibitor NEUF985 with the metal surface. This prevents NEUF985 from tightly adhering to the outside of the base film and forming a complete, dense cross-linked reinforcing film, making it difficult to resist the medium-high temperature of grinding and the erosion of the grinding fluid. This makes the passivation film easily damaged, resulting in poor rust prevention performance. The non-seize load P of the metal grinding fluid provided in Comparative Example 2-3... B The value is lower than that of Example 1 because the metal grinding fluids provided in Comparative Examples 2-3 contain a higher proportion of both rust inhibitors, resulting in strong competitive adsorption between the rust inhibitors and lubricants on the metal surface.

[0058] The metal grinding fluids provided in Comparative Examples 2-4 exhibited inferior rust-preventive and lubricating properties compared to those provided in Example 1. This is because the mass ratio of the specific amine CHO2O to N-methyldiethanolamine is greater than 1, resulting in insufficient N-methyldiethanolamine in the organic base. Furthermore, this imbalance in the organic base ratio can lead to abnormal pH and alkali levels in the metal grinding fluid, affecting the dispersibility of the lubricant and consequently its lubricating performance. The non-seize load P of the metal grinding fluids provided in Comparative Examples 2-5... B The value is lower than that in Example 1 because when the mass ratio of the special amine CH020 to N-methyldiethanolamine is <1 / 2.5, the proportion of N-methyldiethanolamine in the organic base is too high.

[0059] Furthermore, the raw material composition of the metal grinding fluids provided in Example 1, Comparative Example 3-1, Comparative Example 3-2, Comparative Example 3-3, Comparative Example 3-4, Comparative Example 3-5, and Comparative Example 3-6 is shown in Table 5 below.

[0060] Table 5:

[0061] The non-seize load P was tested on the metal grinding fluids provided in Example 1, Comparative Examples 3-1 to 3-6 respectively. B , sintering point P D The test results are shown in Table 6 below. The tapping torque of the metal grinding fluids provided in Example 1, Comparative Examples 3-1 to 3-4 was tested respectively, and the test results are shown in Table 7 below. Furthermore, the ΔT (°C) value in Table 7 is used to characterize the cooling performance of the grinding fluid. It is obtained by monitoring the tool / workpiece temperature before / at the beginning of machining, and the tool / workpiece temperature after continuous grinding for a period of time, and calculating the difference between the two.

[0062] Table 6:

[0063] Table 7:

[0064] As can be seen from the test results in Tables 6 and 7 above, the P of the metal grinding fluid provided in Comparative Example 3-1 is... B Value, P D The values ​​are lower than in Example 1, while the maximum torque and average torque are higher. The cooling performance of the grinding fluid is also inferior to that of Example 1. This is because the grinding fluid provided in Comparative Example 3-1 uses only polyether ester as a lubricant. Polyether ester can only form a physically adsorbed lubricating film under low to medium loads and cannot cope with extreme pressure conditions during grinding. This makes the metal surface extremely prone to adhesive wear under high loads, resulting in no-seize load (P... B ) and sintering point (P DThe temperature drop was significant. However, due to the absence of the extreme pressure anti-wear effect of organic molybdenum, the polyether ester lubricating film was prone to rupture under extreme pressure. Therefore, the dry friction area in direct metal-to-metal contact increased, leading to a substantial increase in frictional resistance during grinding. This resulted in both the maximum torque and average torque being higher than in Example 1, which contained both lubricating components. Simultaneously, the additional heat generated by dry friction exacerbated the temperature rise, deteriorating the cooling performance of the grinding fluid.

[0065] P of the metal grinding fluid provided in Comparative Example 3-2 B Value, P D The P value was lower than that of Example 1, while the maximum torque and average torque were higher. The cooling performance of the grinding fluid was also inferior to that of Example 1. This is because the grinding fluid provided in Comparative Example 3-2 only uses organic molybdenum as a lubricant, which cannot achieve a dual lubrication and protection mechanism of physical adsorption and chemical reaction. The P value of the metal grinding fluid provided in Comparative Example 3-3 was lower than that of Example 1. B Value, P D The values ​​of the grinding fluids in Comparative Example 3-3 are lower than those in Example 1, while the maximum and average torques are higher. The cooling performance of the grinding fluid in Comparative Example 3-4 is also inferior to that in Example 1. This is because the metal grinding fluid in Comparative Example 3-3 did not use lubricant. The maximum and average torques of the grinding fluids in Comparative Example 3-4 are higher than those in Example 1, but the cooling performance is also inferior. This is because the amount of lubricant in the grinding fluids of Comparative Example 3-4 is excessive, resulting in an abnormally high viscosity of the grinding fluid system. This abnormally high viscosity disrupts normal lubrication rheology and heat exchange efficiency. Although excessive lubricant does not affect the extreme pressure performance limit, it reduces the lubricant adsorption and spreading efficiency, leading to a decrease in basic friction reduction capacity, an increase in grinding torque, increased heat exchange resistance, decreased cooling performance, and a significant increase in operating costs, which does not meet the actual needs of industrial production.

[0066] P of the metal grinding fluids provided in Comparative Examples 3-5 B Value, P D The value is lower than that in Example 1 because when the mass ratio of polyether ester to organic molybdenum is <0.8, the amount of polyether ester in the lubricant is too low, resulting in insufficient thickness and reduced density of the physical adsorption film formed on the metal surface. This makes it impossible to effectively isolate the friction pairs in the grinding process, and the basic lubrication effect under low load is greatly reduced.

[0067] P of the metal grinding fluids provided in Comparative Examples 3-6 B Value, P DThe value is lower than that of Example 1 because the mass ratio of polyether ester to organic molybdenum in the metal grinding fluids provided by Comparative Examples 3-6 is >1.2. The low proportion of organic molybdenum in the lubricant will result in insufficient molybdenum disulfide and molybdenum trioxide produced by decomposition under high temperature and high pressure conditions during grinding (especially high-speed grinding of difficult-to-machine metals). As a result, a complete and dense layered solid lubricating film cannot be formed on the metal surface, and the lubrication effect under high temperature and high speed is significantly weakened.

[0068] Furthermore, the raw material composition of the metal grinding fluids provided in Example 2, Comparative Example 4-1, Comparative Example 4-2, and Comparative Example 4-3 is shown in Table 8 below.

[0069] Table 8:

[0070] The rust-preventive properties of the metal grinding fluids provided in Example 2, Comparative Example 4-1, Comparative Example 4-2, and Comparative Example 4-3 were tested, and the test results are shown in Table 9 below.

[0071] Table 9:

[0072] As can be seen from the test results in Table 9 above, the copper corrosion inhibitor has the best overall improvement effect on metal grinding fluid when the concentration is between 0.3% and 0.5%. However, when the amount of copper corrosion inhibitor is too high, the metal grinding fluid system becomes unstable, which may lead to precipitation risks; when the amount of copper corrosion inhibitor is too low, it does not achieve the best effect on the corrosion resistance of the metal.

[0073] Furthermore, the raw material composition of the metal grinding fluids provided in Example 3, Comparative Example 5-1, Comparative Example 5-2, and Comparative Example 5-3 is shown in Table 10 below.

[0074] Table 10:

[0075] The biostability of the metal grinding fluids provided in Example 3, Comparative Example 5-1, Comparative Example 5-2, and Comparative Example 5-3 was tested. The tests were conducted in accordance with the standard ASTM E2275-24, "Standard Practice for Evaluating the Bioresistance and Antimicrobial Pesticide Resistance of Water-Mixable Metalworking Fluids," and the test results are shown in Table 11 below.

[0076] Table 11:

[0077] As can be seen from the test results in Table 11 above, if too much bactericide M722 is added, the metal grinding fluid will have a strong odor, while if too little bactericide M722 is added, the bactericidal effect will be insignificant.

[0078] Furthermore, the raw material composition of the metal grinding fluids provided in Example 1, Comparative Example 6-1, Comparative Example 6-2, and Comparative Example 6-3 is shown in Table 12 below.

[0079] Table 12:

[0080] The defoaming properties of the metal grinding fluids provided in Example 1, Comparative Example 6-1, Comparative Example 6-2, and Comparative Example 6-3 were tested (according to the standard GB / T 6144-2010 Fully Synthetic Cutting Fluids), and the presence of material precipitation in the metal grinding fluids was observed. The test results are shown in Table 12 below.

[0081] Table 13:

[0082] As can be seen from the test results in Table 13 above, when the amount of defoamer is less than 0.1%, the defoaming effect is not obvious. However, when the amount of defoamer is too high, the metal grinding fluid system becomes unstable.

[0083] Furthermore, the raw material composition of the metal grinding fluids provided in Example 1, Comparative Example 7-1, Comparative Example 7-2, and Comparative Example 7-3 is shown in Table 14 below.

[0084] Table 14:

[0085] The sedimentation properties of the metal grinding fluids provided in Example 1, Comparative Example 7-1, Comparative Example 7-2, and Comparative Example 7-3 were tested (according to the standard GB / T 6144-2010 Fully Synthetic Cutting Fluids), and the presence of material precipitation in the metal grinding fluids was observed. The test results are shown in Table 15 below.

[0086] Table 15:

[0087] As can be seen from the test results in Table 15 above, when the amount of the settling agent polyquaternium-2 is too high, the metal grinding fluid system becomes unstable and there is a risk of precipitation.

[0088] 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 metal grinding fluid, characterized in that, The raw materials for its preparation, calculated by mass percentage, include: 60-70% deionized water, 5-15% lubricant, 9-15% organic alkali, 5-10% rust inhibitor, 2-5% bactericide, 0.1-0.5% flocculant, 0.2-0.3% defoamer, and 0.3-0.5% copper corrosion inhibitor; the lubricant is a mixture of polyether ester and organic molybdenum.

2. The metal grinding fluid according to claim 1, characterized in that, The mass ratio of the polyether ester to the organic molybdenum is (0.8–1.2):

1.

3. The metal grinding fluid according to claim 1, characterized in that, The organic base is at least one of the specific amines CH020 and N-methyldiethanolamine.

4. The metal grinding fluid according to claim 1, characterized in that, The rust inhibitor is at least one of monobasic acid and tetrabasic acid.

5. The metal grinding fluid according to claim 4, characterized in that, The monobasic acid is rust inhibitor NEUF685-2, and the tetrabasic acid rust inhibitor is rust inhibitor NEUF985.

6. The metal grinding fluid according to claim 1, characterized in that, The copper corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, and benzotriazole.

7. The metal grinding fluid according to claim 1, characterized in that, The settling agent is polyquaternium-2.

8. The metal grinding fluid according to claim 1, characterized in that, The bactericide is at least one of bactericide M722, bactericide M789F, and isothiazolinone.

9. The metal grinding fluid according to claim 1, characterized in that, The defoamers are defoamer 1875, defoamer 1880, and defoamer 1890.

10. A method for preparing a metal grinding fluid, characterized in that, The preparation of the metal grinding fluid as described in any one of claims 1-9 comprises the following steps: S1. Mix deionized water and organic base, and stir until homogeneous and transparent; S2. Slowly add the rust inhibitor to the mixed solution obtained in step S1 and stir until it is homogeneous and transparent; S3. Add lubricant, bactericide, copper corrosion inhibitor and flocculant to the mixed solution obtained in step S2 in sequence, and stir until homogeneous and transparent; S4. Add defoamer to the mixed solution obtained in step S3, stir evenly to obtain the metal grinding fluid.

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