A fully synthetic quenching steel grinding fluid and a method for preparing the same

Abstract

The application relates to the technical field of grinding fluid, and discloses a fully synthetic hardened steel grinding fluid and a preparation method thereof. The grinding fluid comprises polyoxyethylene polyoxypropylene ether, polyether ester, organic alkali, antirust agent, dispersant, corrosion inhibitor, settling agent, bactericide, small molecule acid and water. The grinding fluid forms a continuous high-strength lubricating film through the combination of polyoxyethylene polyoxypropylene ether and polyether ester, and is compounded with additives such as organic alkali, antirust agent, dispersant, settling agent and small molecule acid to improve the dispersibility of the grinding fluid system during grinding and the settling speed during shutdown, so that the comprehensive performance of the grinding fluid is excellent. The preparation method can prepare the grinding fluid after step-by-step mixing and stirring of the components of the grinding fluid at a suitable temperature, and the preparation method is simple and easy to popularize and apply in industry.

Description

Technical Field

[0001] This invention relates to the technical field of grinding fluids, and particularly to a fully synthetic hardened steel grinding fluid and its preparation method. Background Technology

[0002] Hardened steel is a material with high strength, good wear resistance, high bending strength, excellent tempering properties, and machinability. It is mainly composed of a variety of elements such as iron, carbon, chromium, molybdenum, cobalt, tungsten, manganese, silicon, and nickel. Hardened steel is a general term for a class of steels, mainly including carbon steel, high-speed steel, stainless steel, tool steel, and spring steel. Hardening generally involves the following steps: 1. Heating the steel to its critical temperature, usually between 800℃ and 1000℃, the specific temperature depending on the steel's composition. This step helps restore the crystal structure in the steel to a state called austenite. 2. Then rapidly cooling the heated steel, usually using water, oil, or air. The cooling rate is very important because it determines the final hardness of the steel, as a faster cooling rate results in a harder steel. 3. After hardening, sometimes solution treatment is performed to reduce the brittleness introduced by hardening. This involves reheating the steel to a lower temperature and then cooling it again to improve its toughness and strength. Hardened steel typically reaches a hardness of 40–70 HRC.

[0003] The following properties need to be considered in grinding fluids for hardened steel: 1. Hardened steel is very hard and brittle, and easily generates heat during grinding, thus requiring good cooling and lubrication. 2. The suspension, dispersion, and settling velocity of iron powder. Iron powder should be well suspended and dispersed in the liquid rather than rapidly settling to the bottom. This helps ensure that the iron powder is evenly distributed in the grinding area to provide a consistent grinding effect. However, when the liquid spray stops or weakens, the iron powder needs to have a sufficient settling velocity to quickly settle to the bottom of the liquid for subsequent separation and recovery. 3. Corrosion resistance. The carbon content of hardened steel is usually between 0.3% and 2.1%, and the high carbon content determines its poor corrosion resistance. 4. Antibacterial properties. Grinding fluids are more likely to promote the growth and reproduction of microorganisms than cutting fluids because the iron powder generated during grinding is generally collected and cleaned after sedimentation. Unlike the automatic chip removal of cutting fluids, the iron powder generated during grinding provides an ideal environment for microbial growth. Therefore, the antibacterial properties of grinding fluids are particularly important.

[0004] Most existing grinding fluids are general-purpose products, meaning there are no grinding fluids specifically designed for hardened steel. They fail to consider the characteristics of hardened steel, such as its high hardness and susceptibility to corrosion. Furthermore, existing products focus more on the settling properties of iron powder, neglecting the fact that excessive settling rates can lead to uneven iron powder distribution in the grinding fluid, resulting in uneven grinding marks on the finished product. Moreover, the pH value of these products is often too high, which can cause burning sensations on the user's hands during use. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a fully synthetic hardened steel grinding fluid and its preparation method, which aims to make the grinding fluid have excellent iron powder dispersibility, certain sedimentation properties, and excellent anti-corrosion and antibacterial properties.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A fully synthetic hardened steel grinding fluid, by mass percentage, comprises the following components: 20%–30% polyoxyethylene polyoxypropylene ether, 3%–5% polyether ester, 8%–10% organic base, 6%–10% rust inhibitor, 3%–5% dispersant, 0.3%–0.5% corrosion inhibitor, 0.1%–0.5% settling agent, 2%–3% bactericide, 3%–6% small molecule acid, and water as the balance.

[0008] The fully synthetic hardened steel grinding fluid, wherein the cloud point of the polyoxyethylene polyoxypropylene ether is less than or equal to 37°C, and the cloud point of the fully synthetic hardened steel grinding fluid is less than or equal to 35°C.

[0009] The fully synthetic hardened steel grinding fluid, wherein the organic base is one or more of triisopropanolamine, monoisopropanolamine, N-butyldiethanolamine, and 1-dimethylamino-2-propanol.

[0010] The fully synthetic hardened steel grinding fluid, wherein the rust inhibitor is one or more of a mixture of dicarboxylic acids, acyl amino acids, and diisopropanolamide.

[0011] The fully synthetic hardened steel grinding fluid, wherein the dispersant is polyethylene glycol 400.

[0012] The fully synthetic hardened steel grinding fluid, wherein the settling agent is polyquaternium-2.

[0013] The fully synthetic hardened steel grinding fluid, wherein the small molecule acid is one or both of neodecanoic acid and isooctanoic acid.

[0014] The fully synthetic hardened steel grinding fluid, wherein the corrosion inhibitor is benzotriazole.

[0015] The fully synthetic hardened steel grinding fluid, wherein the bactericide is one or both of ethylene glycol dihydroxymethyl ether and sodium pyridinethione.

[0016] A method for preparing a fully synthetic hardened steel grinding fluid includes the following steps:

[0017] Mix the organic alkali, rust inhibitor and water in the specified proportions at 30-35°C until the solid is completely dissolved to form the first mixture.

[0018] Add polyoxyethylene polyoxypropylene ether, polyether ester, dispersant, flocculant and bactericide to the first mixture in proportion, stir for 30 minutes to form the second mixture;

[0019] Small molecule acid is added to the second mixture in proportion and stirred until the liquid is transparent and clear to obtain the fully synthetic hardened steel grinding fluid.

[0020] Beneficial effects:

[0021] This invention provides a fully synthetic grinding fluid for hardened steel. It forms a continuous, high-strength lubricating film through a combination of polyoxyethylene polyoxypropylene ether and polyether ester. Furthermore, it is compounded with additives such as organic alkali, rust inhibitors, dispersants, settling agents, and small molecule acids to improve the dispersibility of the grinding fluid system during grinding and the settling speed during downtime. This results in workpieces processed with this grinding fluid exhibiting excellent corrosion inhibition and rust prevention properties. The fluid also demonstrates good stability, strong antibacterial ability, and does not separate during long-term storage. Moreover, the combination of organic alkali and small molecule acids maintains a weakly alkaline pH, preventing burns to the hands of workers. Overall, the fluid exhibits excellent performance.

[0022] This invention provides a method for preparing a fully synthetic hardened steel grinding fluid. First, an alkaline solution, a rust inhibitor, and water are mixed and dissolved. Then, a compounded lubricant, dispersant, flocculant, and bactericide are added. The rust inhibitor enhances the solubility of the compounded lubricant in the grinding fluid system, reducing the clarity of the original grinding fluid. The dispersant promotes the uniform dispersion of the components in the system, the flocculant promotes the settling of impurities, and the bactericide is used for corrosion prevention. Finally, a small molecule acid is added to dilute the original grinding fluid and lower the cloud point of the compounded lubricant to less than or equal to 35°C, facilitating the agglomeration and precipitation of large particles of polyether at high temperatures to form an oil film and improve the lubrication performance of the grinding fluid. Attached Figure Description

[0023] Figure 1 The flowchart shows the preparation method of the fully synthetic hardened steel grinding fluid provided by the present invention. Detailed Implementation

[0024] This invention provides a fully synthetic hardened steel grinding fluid and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the scope of protection of the invention.

[0025] Please see Figure 1This invention provides a fully synthetic hardened steel grinding fluid, which, by mass percentage, comprises the following components: 20%–30% polyoxyethylene polyoxypropylene ether, 3%–5% polyether ester, 8%–10% organic base, 6%–10% rust inhibitor, 3%–5% dispersant, 0.3%–0.5% corrosion inhibitor, 0.1%–0.5% settling agent, 2%–3% bactericide, 3%–6% small molecule acid, and water as the balance.

[0026] Both polyoxyethylene polyoxypropylene ether and polyether ester are lubricants. Their combined use effectively reduces the coefficient of friction, forms a uniform lubricating film, improves the lubricity of the grinding fluid, and reduces contact and wear on the steel surface. Furthermore, this combined lubricant exhibits good thermal stability. During grinding, the temperature rise causes the polyoxyethylene polyoxypropylene ether to temporarily precipitate into larger particles. The precipitation of these larger particles effectively improves the lubrication required during grinding (at high temperatures) and prevents "slippage" due to excessively thick oil films. Polyoxyethylene polyoxypropylene ether maintains its lubricating properties under high-speed motion and high shear stress, and is not easily lost or deteriorated.

[0027] The addition of organic bases can act as lubricant synergists, interacting with other additives to improve the oil film properties of friction surfaces, reduce the coefficient of friction, and decrease heat and wear during machining. The introduction of organic bases can also be used to adjust the pH of grinding fluids, keeping them within a suitable range, helping to prevent premature fluid failure and providing protection for metal surfaces. Furthermore, it can neutralize acidic substances, reducing their corrosive effects on steel.

[0028] Rust inhibitors can act as solubilizers for compound lubricants and have a certain solubilizing effect on polyoxyethylene polyoxypropylene ether and polyether ester, effectively enhancing their solubility. However, they cannot completely clarify the stock solution; therefore, small molecule acids need to be added to achieve complete clarification. Furthermore, during grinding, steel may be exposed to a humid environment. The addition of rust inhibitors can form a protective film on the steel surface, isolating oxygen and water, providing effective corrosion protection, and preventing the steel surface from becoming damp and oxidized.

[0029] The addition of dispersants ensures the uniform dispersion of abrasive grains or metal chips during grinding, preventing their aggregation and deposition, and maintaining the homogeneity and stability of the grinding fluid. It interacts with other additives to form a stable lubricating film, providing effective lubrication. It can also adsorb and encapsulate suspended matter, preventing reactions between suspended matter and other components in the grinding fluid, reducing fluid contamination and grease emulsification; and preventing the deposition and sedimentation of solid particles, maintaining the cleanliness and transparency of the grinding fluid.

[0030] The addition of corrosion inhibitors can isolate oxygen and water, alleviate corrosion on the steel surface, reduce the electrochemical reaction rate on the steel surface, delay the occurrence of corrosion, and interact with other additives to improve the oil film performance of the friction surface and reduce the coefficient of friction.

[0031] The addition of flocculants primarily helps treat and control suspended particles, precipitates, or contaminants, thereby improving the cleanliness and performance of the grinding fluid. During grinding, a large number of suspended particles are generated, causing the grinding fluid to become turbid and unstable. Flocculants can combine with suspended particles to form precipitates and promote their rapid settling, effectively separating the suspended particles and keeping the grinding fluid clear and transparent. They can also adsorb and aggregate contaminants such as coolant and grease, causing them to settle to the bottom along with the suspended particles, facilitating subsequent cleaning.

[0032] The addition of small-molecule acids releases acidic ions into the grinding fluid, helping to control its pH value and maintain it within an appropriate range, preventing the fluid from becoming "burning" to the touch. It can also dissolve and remove oxides and deposits on metal surfaces, reacting with oxide layers to form soluble metal salts that dissolve into the grinding fluid, thus cleaning the steel and reducing oxidation. The grinding fluid can also be diluted to lower its cloud point, making it clear and transparent.

[0033] Specifically, the cloud point of the polyoxyethylene polyoxypropylene ether is less than or equal to 37°C, and the cloud point of the fully synthetic hardened steel grinding fluid is less than or equal to 35°C. Since the cloud point of the polyoxyethylene polyoxypropylene ether is below 37°C, adding a rust inhibitor can effectively enhance the solubility of the compounded lubricant. The subsequent addition of small-molecule acids can dilute the grinding fluid concentrate while lowering its cloud point to below 35°C. The fully synthetic hardened steel grinding fluid provided by this invention needs to consider multiple properties such as rust prevention, lubrication, cleaning, and dispersion. Therefore, polyoxyethylene polyoxypropylene ether cannot be used alone. However, when compounded with other additives (rust inhibitors, dispersants, flocculants, bactericides), the cloud point of the concentrate becomes very low, or the concentrate cannot become a uniform liquid. Therefore, a rust inhibitor is needed to increase the solubility of the polyoxyethylene polyoxypropylene ether and polyether ester. However, if too much rust inhibitor is added, the original solution will become stable. After the original solution is diluted to form a diluted solution, the cloud point of the diluted solution will become very high. In this case, it is necessary to use a mixture of rust inhibitor and small molecule acid to solubilize and lower the cloud point, so as to control the cloud point of the diluted solution to be less than or equal to 35°C.

[0034] The low turbidity point of the diluent facilitates the aggregation of polyoxyethylene polyoxypropylene ether at high temperatures, allowing it to precipitate as larger molecules to form an oil film. The precipitated particles have a size range of 0.1–1 μm, which is smaller than the average particle size of traditional emulsifiers, thus ensuring the lubrication performance required during grinding.

[0035] This grinding fluid uses polyoxyethylene polyoxypropylene ether and polyether ester as the main lubricating raw materials, and is compounded with organic alkali, rust inhibitor, dispersant, flocculant, bactericide, corrosion inhibitor and small molecule acid to form a lubrication system with a high turbidity point of the original solution and a low turbidity point of the diluted solution, so that the grinding fluid has excellent lubricity and can form a continuous high-strength oil film.

[0036] Specifically, the organic base is one or more of triisopropanolamine, monoisopropanolamine, N-butyldiethanolamine, and 1-dimethylamino-2-propanol. These substances are all organic alcohol amines, used to adjust the alkalinity of the grinding fluid, stabilize it, improve its lubrication performance, and reduce steel corrosion.

[0037] Specifically, the rust inhibitor is one or more of a mixture of dicarboxylic acids, acyl amino acids, and diisopropanolamide. In this embodiment, the rust inhibitor is a compound of the above three rust inhibitors. The rust inhibitor compounded in this way can significantly improve the solubility of the compounded lubricant, and by changing the electrochemical properties of the metal surface, it interferes with the electron transfer process between the metal and other substances, thereby reducing the corrosion rate of the metal and improving the rust prevention effect.

[0038] Specifically, the dispersant is polyethylene glycol 400. Polyethylene glycol 400 is a hydrophilic solvent that promotes the compatibility of the components in the grinding fluid system, facilitates the uniform dispersion of the components in the system, improves the dispersion stability of the components, and gives the grinding fluid suitable viscosity and fluidity.

[0039] Specifically, the settling agent is polyquaternium salt-2. Polyquaternium salt-2 can adsorb suspended substances, metal ions, grease, etc. in the grinding fluid, encapsulate and aggregate them into larger precipitates, which are then easily removed from the grinding fluid after settling, thus improving the cleanliness and clarity of the grinding fluid.

[0040] Specifically, the small molecule acid is one or both of neodecanoic acid and isooctanoic acid. These small molecule acids are organic acids; neodecanoic acid has an acid value of 80–110 mgKOH / g, and isooctanoic acid has an acid value of 1–5 mgKOH / g. Neodecanoic acid and isooctanoic acid function as solubilizers, lower pH, and reduce cloud point in the system. The acid values ​​of neodecanoic acid and isooctanoic acid must be within a suitable range. Excessively high acid values ​​can reduce the lubricity of the grinding fluid, while excessively low acid values ​​require the addition of more small molecule acid to adjust the pH of the grinding fluid.

[0041] Specifically, the corrosion inhibitor is benzotriazole. Benzotriazole is a commonly used copper corrosion inhibitor that can be adsorbed onto the metal surface to form a protective film, preventing the metal from contacting the corrosive medium in the grinding fluid. Moreover, it still has good corrosion inhibition performance under high temperature conditions, making it suitable for high-temperature processing environments.

[0042] Specifically, the bactericide is one or both of ethylene glycol dihydroxymethyl ether and sodium pyrithione. The addition of these substances can disrupt the cell structure of microorganisms such as bacteria and fungi, inhibiting the growth of microorganisms in the grinding fluid and preventing problems such as fermentation and deterioration of the grinding fluid caused by microbial growth.

[0043] This fully synthetic hardened steel grinding fluid has the following advantages:

[0044] 1. It exhibits excellent iron powder dispersibility during grinding and excellent iron powder settling properties when the solution is still.

[0045] 2. It has good cleaning performance, does not contain mineral oil, vegetable oil or other oil-based components, and all additives are water-soluble, so no further cleaning is required after the workpiece is processed.

[0046] 3. Safe and environmentally friendly, it does not contain harmful substances such as sulfur, chlorine, and nitrite. It is safe to store, does not irritate the skin or respiratory tract during use, is easily degradable, and is environmentally friendly.

[0047] 4. It has good corrosion inhibition and rust prevention properties. Under normal temperature conditions, the workpiece can remain rust-free for 7 days after processing.

[0048] 5. High stability; does not discolor or separate during long-term storage.

[0049] 6. The pH value is close to neutral, and normal human contact will not cause a burning sensation due to excessively high pH value.

[0050] Please see Figure 1 The present invention also provides a method for preparing a fully synthetic hardened steel grinding fluid, comprising the following steps:

[0051] (1) Mix organic alkali, rust inhibitor and water in proportion, and stir at 30-35°C until the solid is completely dissolved to form the first mixture.

[0052] (2) Add polyoxyethylene polyoxypropylene ether, polyether ester, dispersant, flocculant and bactericide to the first mixture in proportion, stir for 30 minutes to form the second mixture.

[0053] (3) Add small molecule acid to the second mixture in proportion and stir until the liquid is transparent and clear to obtain the fully synthetic hardened steel grinding fluid.

[0054] In the above preparation method, the alkaline solution, rust inhibitor, and water are first mixed and miscible; then, a compounded lubricant, dispersant, flocculant, and bactericide are added. The rust inhibitor is used to improve the solubility of the compounded lubricant in the grinding fluid system and reduce the clarity of the grinding fluid stock solution. The dispersant promotes the uniform dispersion of each component in the system, the flocculant promotes the sedimentation of impurities in the system, and the bactericide is used for corrosion prevention. Finally, a small molecule acid is added to dilute the grinding fluid stock solution and lower the cloud point of the compounded lubricant to less than or equal to 35°C, so that the polyether can agglomerate and precipitate large particles at high temperature to form an oil film and improve the lubrication performance of the grinding fluid.

[0055] To further illustrate the fully synthetic hardened steel grinding fluid and its preparation method provided by the present invention, the following examples and tests are provided.

[0056] The test method of the present invention

[0057] Test subjects: Grinding fluid stock solutions prepared in each embodiment and comparative example, and the grinding fluid stock solutions were diluted to a 5% dilution.

[0058] The test items are as follows:

[0059] (1) Appearance (visual inspection), refractive index (in accordance with standard ASTM D1218); pH value (in accordance with standard ASTM D1293, GB / T 6144-2010); foam test (in accordance with standard CNOMO ANTIFOAM D65-5212); aluminum sheet corrosion (aluminum sheet material ADC12) (in accordance with standard GB / T 6144-2010); cast iron sheet corrosion (cast iron sheet material HT300) (in accordance with standard GB / T 6144-2010); copper sheet corrosion (copper sheet material T3) (in accordance with standard GB / T 6144-2010).

[0060] (2) The extreme pressure performance test method shall be in accordance with GB / T12583-1998. Tester model: Xiamen Tianji MS-10A.

[0061] (3) Testing method for tapping torque: Tapping speed 2000 r / min, depth 20 mm, maximum torque 300 Ncm, cutting tool: TTT-M4F-TIN-T; 45# steel: TTT-testbar 1.0503-M4F / 3.720 mm. Extrusion speed 2000 r / min, depth 12 mm, maximum torque 300 Ncm, cutting tool: TTT-M4C-TIN-T; 45# steel: TTT-testbar 1.0503-M4C / 3.312 mm. Tester model: TAP TTTSystem-G8.

[0062] (4) SRV multi-functional friction and wear testing machine, lubrication performance test method: temperature 25℃, load: 100N, stroke: 2.5mm, frequency: 20Hz, test temperature: 25℃, running time: 5min, upper ball: YG8, lower specimen: hardened steel.

[0063] (5) Stability test method: Performed according to GB / T 6144-2010. The test object was sealed and left to stand at room temperature (25℃) for 12 hours, and the state changes were observed. The test object was sealed and left to stand at high temperature (70℃) for 5 hours. After taking it out, the solution was allowed to cool to room temperature and the separation was observed. Then, the test object was placed in a refrigerator at low temperature (-13±2℃) and sealed and left to stand for 24 hours. After taking it out, the solution was allowed to rise to room temperature and the separation was observed.

[0064] I. Polyether Examples

[0065] The grinding fluid was prepared according to the addition amounts of each component in Table 1 below and the preparation method described above.

[0066] Table 1 shows the components of Example 1, Comparative Example 1-1, Example 1-2, and Example 1-3.

[0067]

[0068]

[0069] Table 2 shows the test results for Example 1, Comparative Example 1-1, Example 1-2, and Example 1-3.

[0070]

[0071]

[0072] As can be seen from the test results in Table 2, Example 1 exhibits the best lubrication performance, the lowest coefficient of friction, and the lowest surface roughness. Examples 1-2 and 1-3 show the next best lubrication performance, while Comparative Example 1-1 exhibits the worst lubrication performance. RPE 2520 has a molecular weight of approximately 3100 and a cloud point of 31℃, RPE 1050 has a molecular weight of approximately 1950 and a cloud point of 64℃, and RPE 1720 has a molecular weight of approximately 2150 and a cloud point of 37℃. The differences in molecular weight and cloud point result in RPE 1720 and RPE 1050 having inferior lubrication performance compared to RPE 2520. Furthermore, RPE 2520's lower cloud point makes it easier for larger particles to precipitate, thus facilitating film-forming lubrication.

[0073] II. Examples of Organic Bases

[0074] The corresponding grinding fluid was prepared according to the addition amount of each component in Table 3 below and the preparation method described above.

[0075] Table 3 shows the components of Example 2, Example 2-1, Comparative Example 2-2, and Comparative Example 2-3.

[0076]

[0077] Table 4 shows the test results for Example 2, Example 2-1, Comparative Example 2-2, and Comparative Example 2-3.

[0078]

[0079]

[0080] As can be seen from the test results in Table 4, Example 2 exhibits the best lubrication performance, the lowest coefficient of friction, and the lowest surface roughness. Example 2-1 shows the second best lubrication performance, while Comparative Examples 2-2 and 2-3 show poor lubrication performance. In Comparative Examples 2-2 and 2-3, corrosion occurred on the aluminum sheets after immersion in the corrosion solution. Different organic bases possess different functional groups and branches; the more functional groups and branches, the better the improvement in the lubrication performance of the grinding fluid. Furthermore, the alkalinity of the organic base also affects lubrication performance, but excessive alkalinity can lead to alkali-catalyzed ring-opening reactions, reducing lubrication performance.

[0081] III. Examples of Small Molecule Acids

[0082] The corresponding grinding fluid was prepared according to the addition amount of each component in Table 5 below and the preparation method described above.

[0083]

[0084]

[0085] Table 6 shows the test results for Example 3, Example 3-1, Comparative Example 3-2, and Comparative Example 3-3.

[0086]

[0087]

[0088] As can be seen from the test results in Table 6, Example 3 exhibits the best lubrication performance, with the lowest coefficient of friction and surface roughness. Example 3-1 shows the second best lubrication performance, while Comparative Examples 3-2 and 3-3 show poor lubrication performance. The cast iron sheets in Comparative Examples 3-2 and 3-3 showed corrosion after immersion in the grinding fluids. In Example 3, the acid value of neocapric acid is 80–110 mg KOH / g; in Example 3-1, the acid value of isooctanoic acid is 1–5 mg KOH / g; in Comparative Example 3-2, the acid value of n-octanoic acid is 200–300 mg KOH / g; and in Comparative Example 3-3, the acid value of isononanoic acid is 190–210 mg KOH / g. Excessive acidity can also lead to acid-catalyzed ring-opening reactions, reducing the lubrication performance of the grinding fluid. Furthermore, acid can neutralize some organic bases, creating a weakly alkaline pH environment, which is beneficial for protecting the operator's skin and discourages bacterial growth.

[0089] This invention addresses the problems of excessively high pH value, excessively rapid iron powder settling rate, and insufficient corrosion resistance and antibacterial properties in fully synthetic grinding fluids. It combines polyether and polyether ester to form a continuous high-strength lubricating film, and combines it with additives such as small molecule acids, dispersants, and settling agents to improve dispersion performance during processing and settling speed during downtime. It also solves the problem of uneven grinding marks on the workpiece surface after grinding.

[0090] To address the surface roughness of workpieces after grinding, an experiment simulating on-site grinding was designed. The SRV multi-functional friction and wear testing machine was used for quantitative and timed testing to simulate the grinding marks that appear on the workpiece surface after on-site grinding. The surface roughness was analyzed using three-dimensional white light. It was found that the fully synthetic hardened steel grinding fluid provided by this invention has excellent lubrication performance for the workpiece and causes little wear on the workpiece surface.

[0091] It is understood that those skilled in the art can make equivalent substitutions or changes to the technical solution and inventive concept of the present invention, and all such changes or substitutions should fall within the protection scope of the present invention.

Claims

1. A fully synthetic grinding fluid for hardened steel, characterized in that, The fluid comprises the following components by mass percentage: 20%–30% polyoxyethylene polyoxypropylene ether, 3%–5% polyether ester, 8%–10% organic base, 6%–10% rust inhibitor, 3%–5% dispersant, 0.3%–0.5% corrosion inhibitor, 0.1%–0.5% settling agent, 2%–3% bactericide, 3%–6% small molecule acid, and water as the balance; the turbidity point of the polyoxyethylene polyoxypropylene ether is less than or equal to 37°C, and the polyoxyethylene polyoxypropylene ether is RPE 2520; the turbidity point of the fully synthetic hardened steel grinding fluid is less than or equal to 35°C; the organic base is a combination of triisopropanolamine, monoisopropanolamine, N-butyldiethanolamine, and 1-dimethylamino-2-propanol; the rust inhibitor is a compound product of dicarboxylic acid mixture, acyl amino acid, and diisopropanolamide; the dispersant is polyethylene glycol 400; and the small molecule acid is one or both of neodecanoic acid and isooctanoic acid.

2. The fully synthetic hardened steel grinding fluid according to claim 1, characterized in that, The settling agent is polyquaternium-2.

3. The fully synthetic hardened steel grinding fluid according to claim 1, characterized in that, The corrosion inhibitor is benzotriazole.

4. The fully synthetic hardened steel grinding fluid according to claim 1, characterized in that, The bactericide is one or both of ethylene glycol dihydroxymethyl ether and sodium pyrithione.

5. A method for preparing a fully synthetic hardened steel grinding fluid, characterized in that, Includes the following steps: Mix the organic alkali, rust inhibitor and water in the specified proportions at 30-35°C until the solid is completely dissolved to form the first mixture. Add polyoxyethylene polyoxypropylene ether, polyether ester, dispersant, flocculant and bactericide to the first mixture in proportion, stir for 30 minutes to form the second mixture; A small molecule acid is added to the second mixture in proportion, and the mixture is stirred until the liquid is transparent and clear to obtain the fully synthetic hardened steel grinding fluid as described in any one of claims 1-4.

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