Wire cutting working fluid and preparation method thereof

Abstract

The invention belongs to the technical field of cooling liquid for machining, and particularly relates to wire cutting working liquid and a preparation method thereof. The wire cutting working fluid is prepared from the following components in percentage by mass: 30.0 to 35 percent of basic components, 0.5 to 5.0 percent of plant extract, 1.0 to 4.0 percent of antirust agent, 1.0 to 4.0 percent of surfactant, 1.0 to 4.0 percent of extreme pressure lubricant, 0.5 to 2.0 percent of pH stabilizer, 0.1 to 0.5 percent of defoaming agent and the balance of deionized water. According to the linear cutting working fluid, through cooperative use of specific compound microbial agents (lactobacillus plantarum and saccharomyces cerevisiae) and compound enzymes (nattokinase and cellulase), the antibacterial performance, the rust prevention performance, the stability and other performance of the linear cutting working fluid are improved, and the linear cutting working fluid has wide application prospects.

Description

Technical Field

[0001] This invention belongs to the field of coolant technology for machining, specifically a wire EDM working fluid and its preparation method. Background Technology

[0002] Wire EDM is a special machining technology that uses the principle of electrical discharge to precisely machine conductive materials. During operation, a tiny gap is maintained between the workpiece and the electrode wire. Under the action of a pulsed power supply, a high-frequency discharge is generated, and cutting is achieved by melting the material through instantaneous high temperature. The working fluid, as a key medium in this process, not only directly affects the discharge efficiency, machining accuracy, and surface quality, but also plays a decisive role in machining stability, electrode wire life, and environmental safety.

[0003] Traditional wire EDM fluids are mainly divided into two categories: oil-based and water-based. Oil-based fluids have good lubrication but poor cooling performance, and poor biodegradability and stability; water-based fluids have better cooling, lubrication, and cleaning performance, and are less expensive than oil-based fluids, but they still generally have the following problems: 1. Poor antibacterial properties: Under prolonged use and high-temperature environments, bacteria and mold can easily grow, causing the working fluid to deteriorate, produce odors, and reduce performance, requiring frequent replacement.

[0004] 2. Balancing lubrication and rust prevention is challenging: to improve cutting smoothness and efficiency, good extreme pressure lubrication is required; to prevent workpiece and machine tool corrosion, rust inhibitors need to be added. The two often conflict with each other.

[0005] 3. Environmental and health pressures: Traditional additives such as certain mineral oils, phenolic bactericides, and nitrite rust inhibitors pose potential hazards to human health and the environment.

[0006] 4. Chip removal and cleaning performance need improvement: Effective removal of electro-erosion products is the key to ensuring cutting stability and efficiency. Summary of the Invention

[0007] To address the above problems, this invention provides a wire EDM working fluid and its preparation method, which solves the problems of poor antibacterial properties, difficulty in balancing lubrication and rust prevention, environmental impact, and poor chip removal and cleaning performance of existing wire EDM working fluids.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a wire EDM working fluid, which, by mass fraction, comprises: a base component: 30.0%~35%, plant extracts: 0.5%~5.0%, rust inhibitor: 1.0%~4.0%, surfactant: 1.0%~4.0%, extreme pressure lubricant: 1.0%~4.0%, pH stabilizer: 0.5%~2.0%, defoamer: 0.1%~0.5%, and deionized water: balance; The plant extract is obtained by fermentation and enzymatic hydrolysis of rapeseed and rosemary leaves; preferably, the amount of plant extract added is 1.5% to 3.0%.

[0009] The preparation method of the plant extract includes: mixing and crushing rapeseed and rosemary leaves, adding 6-10 times the mass of deionized water, dispersing by ultrasonication, inoculating with a compound microbial agent, fermenting to obtain a fermentation broth, adding a compound enzyme for enzymatic hydrolysis, and obtaining the plant extract.

[0010] Preferably, the ultrasonic treatment temperature is 30-40℃; the ultrasonic frequency is 50-65kHz; and the ultrasonic time is 20-40min. Ultrasonic treatment can disperse the active ingredients in rapeseed and rosemary leaves in the solution, which is beneficial to subsequent fermentation operations.

[0011] Preferably, the compound microbial agent consists of Lactobacillus plantarum and Saccharomyces cerevisiae, with a mass ratio of Lactobacillus plantarum to Saccharomyces cerevisiae of 1:2-4; the total inoculum is 1% to 3% of the total mass of rapeseed and rosemary leaves; and anaerobic fermentation is carried out for 5-15 days under natural conditions of 30-37℃ and pH.

[0012] Preferably, the rapeseed and rosemary leaves are pulverized to 60-200 mesh; the mass ratio of rapeseed to rosemary leaves is 5-10:1.

[0013] The composite enzyme described in this invention is composed of nattokinase and cellulase in a weight ratio of 1:3-4. The enzymatic hydrolysis temperature is 30-40℃, the pH value is preferably 6-7, the enzyme addition amount is preferably 1%-2%, and the time is 40-60 minutes.

[0014] This invention combines fermentation and enzymatic hydrolysis, and utilizes specific compound microbial agents (Lactobacillus plantarum and Saccharomyces cerevisiae) and compound enzymes (nattokinase and cellulase) to decompose macromolecules (such as cellulose, pectin, and protein) in raw materials into small-molecule organic acids (such as lactic acid and acetic acid), polyphenols, and other active ingredients, which can further inhibit the growth of bacteria and mold. Polyphenols can form a strong adsorption film on the surface of workpieces and electrode wires, effectively reducing friction. The functional groups of polybasic acids and polyphenols can chelate with metal ions to form a dense protective film on the metal surface, blocking the electrochemical corrosion process and providing long-lasting rust protection. The components in the fermentation extract have good compatibility with the aqueous phase and can be uniformly and stably dispersed in the working fluid, without stratification or deterioration during long-term storage.

[0015] The basic component is at least one of glycerol and glycerol borate.

[0016] The rust inhibitor is at least one of sebacic acid and dodecanoic acid.

[0017] The surfactant is polyethylene glycol.

[0018] The extreme pressure lubricant is at least one of tetrameric castor oil ester, polyglycerol fatty acid ester, pentaerythritol oleate, sebacic acid diester, and azelaic acid diester.

[0019] The pH stabilizer is at least one of triethanolamine, diethanolamine, and sodium carbonate.

[0020] The defoamer is an organosilicone defoamer.

[0021] Secondly, the present invention provides a method for preparing the wire cutting working fluid described in the first aspect, the specific steps of which are as follows: Weigh the above components according to the mass percentage, and stir them at 500-800 rpm at 30-40℃ until a homogeneous and transparent solution is formed.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. Synergistic Natural Antibacterial and Antiseptic Properties: Through specific microbial fermentation and enzymatic hydrolysis, the macromolecules in plant materials are decomposed into small-molecule organic acids, polyphenols, flavonoids, and other active ingredients, inhibiting the growth of bacteria and mold, fundamentally solving the problem of easy spoilage in the working fluid, and significantly extending the fluid replacement cycle. The biosurfactants and small-molecule polyphenols produced by fermentation can form a strong adsorption film on the surface of the workpiece and electrode wire, effectively reducing friction. At the same time, some components in the fermentation products may undergo a mild reaction with the metal surface at the high temperature of discharge, forming a loose modified layer that is easily washed away, which is beneficial for chip removal, thereby indirectly improving cutting speed and surface quality. The functional groups such as polybasic acids and polyphenols in plant materials and fermentation products can chelate with metal ions to form a dense protective film on the metal surface. This film works synergistically with rust inhibitors to block the electrochemical corrosion process, providing long-lasting rust protection and avoiding the use of harmful substances such as nitrites.

[0023] 2. Environmental friendliness and safety: The plant raw materials are all renewable resources, the fermentation process is green and mild, the final product has good biodegradability, and other raw materials have little skin irritation to operators, which is in line with the development trend of green manufacturing.

[0024] 3. The present invention uses specific raw materials, and the components of the wire cutting working fluid obtained have good compatibility with the aqueous phase, can be uniformly and stably dispersed in the working fluid, and do not separate or deteriorate during long-term storage. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solution, the present invention will be described in detail below with reference to embodiments. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0026] Example 1: Preparation of plant extracts Rapeseed and rosemary leaves were mixed and pulverized at a mass ratio of 6:1. The mixture was then pulverized through a 200-mesh sieve to obtain plant powder. Nine times the mass of deionized water was added, and the mixture was ultrasonically dispersed at 40℃ and 65kHz for 35 minutes. A compound microbial agent (Lactobacillus plantarum and Saccharomyces cerevisiae in a mass ratio of 1:3, with an inoculum amount of 1% of the total weight of rapeseed and rosemary leaves) was then inoculated. Anaerobic fermentation was carried out for 8 days at 37℃ and natural pH conditions. The mixture was sterilized and filtered to obtain the fermentation broth. Nattokinase and cellulase (nattokinase and cellulase in a mass ratio of 1:3) were added, and the mixture was enzymatically hydrolyzed at 30℃ and pH 6.5 for 50 minutes. The enzymes were then inactivated, and the mixture was filtered through an ultrafiltration membrane. The filtrate with a concentration less than 1 kDa was collected to obtain the plant extract.

[0027] Example 2: A wire EDM working fluid, by mass fraction, comprising: 30.0% glycerol, 5.0% plant extract prepared in Example 1, 2.0% sebacic acid, 4.0% polyethylene glycol, 2.0% sebacic acid diester, 0.5% diethanolamine, 0.3% defoamer, and deionized water: balance; The above components are stirred and mixed evenly at 45°C and 600 rpm until a uniform and transparent solution is formed, which is the wire cutting working fluid of the present invention.

[0028] Example 3: A wire EDM working fluid, by mass fraction, comprising: 30.0% glycerol borate, 5.0% plant extract prepared in Example 1, 2.0% dodecanoic acid, 4.0% polyethylene glycol, 2.0% pentaerythritol oleate, 0.5% sodium carbonate, 0.3% defoamer, and deionized water: balance; The above components are stirred and mixed evenly at 45°C and 700 rpm until a uniform and transparent solution is formed, which is the wire cutting working fluid of the present invention.

[0029] Example 4: A wire EDM working fluid, which, by mass fraction, comprises: 35.0% glycerol, 3.0% plant extract prepared in Example 1, 3.0% sebacic acid, 3.0% polyethylene glycol, 4.0% sebacic acid diester, 0.2% diethanolamine, 0.5% defoamer, and deionized water: balance; The above components are stirred and mixed evenly at 50°C and 500 rpm until a uniform and transparent solution is formed, which is the wire cutting working fluid of the present invention.

[0030] Comparative Example 1 No plant extracts were added; instead, an equal amount of polyethylene glycol was used. The remaining components and preparation method were the same as in Example 2.

[0031] Comparative Example 2 Add unfermented plant extract: Boil equal proportions of rapeseed and rosemary leaves directly in water to extract the extract, concentrate it to the same solid content as in Example 1, and replace the fermented extract in Example 2. The rest is the same as in Example 2.

[0032] Comparative Example 3 In Example 1, only Saccharomyces cerevisiae was used as the microbial agent; only cellulase was used for enzymatic hydrolysis, and the rest was the same as in Example 1, to prepare plant extract A.

[0033] Comparative Example 4 The plant extract in Example 2 was replaced with plant extract A prepared in Comparative Example 3, and it was the same as in Example 2.

[0034] Performance testing: The wire cutting working fluids prepared in Examples 2-4 and Comparative Examples 1-2 and 4 were diluted 5 times and tested.

[0035] 1. Antimicrobial properties test (accelerated test): The initial inoculation concentration was approximately 1.0 × 10⁻⁶ to 100 mL of each working solution to be tested. 6 A mixed bacterial suspension (containing Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538) at CFU / mL was incubated statically at 32°C. Samples were taken on days 0 (immediately after inoculation), 1, 3, 7, 14, 21, and 28, and the total viable count was determined using the plate count method.

[0036] In Example 2, the total viable bacterial count in the working solution decreased to <1.0 × 10⁻⁶ within 24 hours after inoculation. 2 The concentration of CFU / mL remained below 1.0 × 10⁻⁶ throughout the entire 28-day testing period. 2 ~5.0×10 2 The extremely low CFU / mL level demonstrated both immediate bactericidal and long-lasting antibacterial effects. Examples 3-4 also exhibited immediate bactericidal and long-lasting antibacterial effects, maintaining levels consistently below 1.0 × 10⁻⁶ CFU / mL throughout the 28-day testing period. 2 ~ 5.0×10 2 Extremely low levels of CFU / mL.

[0037] The total viable bacterial count in the working solution of Comparative Example 1 rapidly increased to >1.0 × 10⁻⁶ on the 3rd day after inoculation. 7 CFU / mL, reaching >1.0×10 on day 7. 8The concentration of CFU / mL, accompanied by a noticeable putrid odor and liquid stratification, indicates that it has absolutely no antibacterial ability. Although plant extracts were added in Comparative Example 2, fermentation and enzymatic hydrolysis were not employed, and therefore it did not demonstrate superior antibacterial ability; the total viable cell count decreased to approximately 1.0 × 10⁻⁶ in the first three days. 4 (CFU / mL), but then began to rise, exceeding 1.0×10 on day 14. 6 CFU / mL, reaching >1.0×10⁻⁶ on day 28. 7 The concentration of CFU / mL initially showed some antibacterial activity, but this effect could not be maintained for long and was easily adapted to or decomposed by microorganisms. Comparative Example 4 showed some antibacterial and bacteriostatic ability, maintaining a concentration of 10 CFU / mL over the 28-day testing period. 4 The CFU / mL level indicates poor antibacterial and bacteriostatic effects.

[0038] 2. Cutting performance test: Under the same machine tool parameters (DK7732, cutting 40mm thick Cr12 mold steel), the average cutting speed (cutting area per unit time), surface roughness (using MarSurf M300 roughness tester, taking the average value of the center and four sides of the cutting surface) and the uniformity of the cutting surface were tested (visual observation and 50x optical microscope observation), as shown in Table 1.

[0039] Table 1

[0040] Therefore, it can be seen that the cutting performance of embodiments 2-4 of the present invention is significantly better than that of the comparative examples.

[0041] 3. Rust prevention test: Immerse the 45# steel test piece halfway in each diluted working solution and place it in a constant temperature and humidity chamber at 40℃ and 90% humidity for 48 hours. After 48 hours, remove it, rinse it with deionized water, blow it dry, and observe the interface between the liquid and the liquid surface and the part above the liquid visually and under a microscope.

[0042] In Examples 2-4, the portions of the test pieces above the liquid surface showed no rust, with only slight color change at the liquid surface interface. In Comparative Example 1, obvious rust spots appeared at the interface. Comparative Example 2 showed rust spots. Comparative Example 4 showed slight rust spots.

[0043] 4. Stability Test: The working solutions prepared in Examples 2-4 and Comparative Examples 1-2 and 4 were placed in environments of -5℃ and 50℃ for 7 days each, and observed after returning to room temperature. Examples 2-4 showed no stratification, precipitation, or crystallization. Comparative Example 1 showed slight stratification. Comparative Examples 2 and 4 showed slight turbidity after returning to room temperature and required shaking to mix thoroughly.

[0044] After the working solutions prepared in Examples 2-4 and Comparative Examples 1-2 and 4 were left at room temperature for 6 months, the working solutions prepared in Examples 2-4 were clear in appearance. The working solution prepared in Comparative Example 1 had a small amount of precipitate, and the working solutions prepared in Comparative Examples 2 and 4 were slightly yellow in appearance.

[0045] It should be noted that, in this document, the terms "comprising," "including," and any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Specific examples have been used in this document to illustrate the principles and implementation methods of the present invention. These examples are merely for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be pointed out that, due to the limitations of written expression and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or variations without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the concept and technical solution of the present invention to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A wire EDM working fluid, characterized in that, The wire cutting working fluid, by mass fraction, comprises: base components: 30.0%~35%, plant extracts: 0.5%~5.0%, rust inhibitors: 1.0%~4.0%, surfactants: 1.0%~4.0%, extreme pressure lubricants: 1.0%~4.0%, pH stabilizers: 0.5%~2.0%, defoamers: 0.1%~0.5%, and deionized water: balance; the plant extracts are obtained from rapeseed and rosemary leaves through fermentation and enzymatic hydrolysis.

2. The wire EDM working fluid according to claim 1, characterized in that, The preparation method of the plant extract includes: mixing and crushing rapeseed and rosemary leaves, adding 6 to 10 times the mass of deionized water, dispersing by ultrasonication, inoculating with a compound microbial agent, fermenting to obtain a fermentation broth, adding a compound enzyme for enzymatic hydrolysis, and obtaining the plant extract.

3. The wire EDM working fluid according to claim 2, characterized in that, The ultrasonic treatment temperature is 30~40℃; the ultrasonic frequency is 50~65kHz; and the ultrasonic time is 20~40min.

4. The wire EDM working fluid according to claim 2, characterized in that, The compound microbial agent consists of Lactobacillus plantarum and Saccharomyces cerevisiae, with a mass ratio of 1:2 to 4. The total inoculum is 1% to 3% of the total mass of rapeseed and rosemary leaves. Anaerobic fermentation is carried out for 5 to 15 days under natural conditions of 30 to 37°C and pH.

5. The wire EDM working fluid according to claim 1, characterized in that, Rapeseed and rosemary leaves are ground to 60-200 mesh; the mass ratio of rapeseed to rosemary leaves is 5-10:

1.

6. The wire EDM working fluid according to claim 2, characterized in that, The compound enzyme consists of nattokinase and cellulase in a weight ratio of 1:3-4. The enzymatic hydrolysis temperature is 30-40℃, the pH value is preferably 6-7, the enzyme addition amount is preferably 1%-2%, and the time is 40-60 minutes.

7. The wire EDM working fluid according to claim 1, characterized in that, The base component is at least one of glycerol and glycerol borate; the rust inhibitor is at least one of sebacic acid and dodecanoic acid.

8. The wire EDM working fluid according to claim 1, characterized in that, The surfactant is polyethylene glycol; the defoamer is an organosilicone defoamer.

9. The wire EDM working fluid according to claim 1, characterized in that, The extreme pressure lubricant is at least one of tetrameric castor oil ester, polyglycerol fatty acid ester, pentaerythritol oleate, sebacic acid diester, and azelaic acid diester.

10. The method for preparing the wire EDM working fluid according to any one of claims 1 to 9, characterized in that, The specific steps are as follows: Weigh the above components according to the mass percentage, stir and mix them evenly at 30~40℃ and a speed of 500~800 rpm until a uniform and transparent solution is formed.

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