Efficient drilling and milling combined machining process for tubular pile end plate

Abstract

The invention relates to the field of metal working fluids, and discloses an efficient drilling and milling combined machining process for a tubular pile end plate, and the working fluid comprises a dual rheological response association polymer, a latent activation type core-shell structure nano lubricant and a tool in-situ self-repairing metal organic precursor. Physical and chemical effects in the machining process are ingeniously utilized, the shear thinning characteristic of the associated polymer ensures macroscopic flowing and cooling efficiency, and the temperature thickening phase change of the associated polymer at the high temperature in a cutting area forms a high-viscosity gel film; according to the gel film, the nano lubricant and the metal organic precursor which are synchronously thermally activated can be synergistically enriched on a friction interface, and a high-energy-efficiency composite lubricating layer is constructed. The invention fundamentally solves the contradiction between cooling and lubrication of the traditional working fluid in combined machining, and revolutionarily prolongs the service life of a cutter by endowing the working fluid with an active repair function, and obviously improves the machining efficiency and the surface quality of a workpiece.

Description

Technical Field

[0001] This invention relates to the field of metalworking fluid technology, and in particular to a high-efficiency drilling and milling composite machining process for pipe pile end plates. Background Technology

[0002] Pipe piles, as widely used foundation components in modern construction, require precise drilling and milling of their end plates during manufacturing to ensure subsequent connection strength and installation accuracy. Drilling-milling composite machining is a highly efficient processing method that integrates drilling and milling processes with different characteristics into a single clamping operation, which is of great significance for improving the production efficiency and processing quality of pipe pile end plates. However, this composite machining mode also poses extremely demanding challenges to the auxiliary systems of the machining process, especially the metalworking fluid.

[0003] Currently, metalworking fluids used in this type of machining are mainly traditional emulsions, semi-synthetic fluids, or fully synthetic fluids. While these fluids can provide some cooling and lubrication under normal, single-operation conditions, their inherent limitations become apparent when dealing with the drastically changing conditions of drilling and milling. On the one hand, the high-speed milling stage requires the fluid to have excellent fluidity and heat transfer properties to quickly remove a large amount of cutting heat and prevent thermal deformation of the tool and workpiece, which requires the fluid to have low viscosity. On the other hand, the subsequent heavy-duty drilling stage is accompanied by extremely high axial forces and cutting torques, requiring the fluid to form a high-strength oil film between the tool and the hole wall to resist extreme pressure and reduce friction, which in turn requires the fluid to have high viscosity. Traditional metalworking fluids have static viscosity characteristics and cannot dynamically respond to these two diametrically opposed needs. Therefore, developers can only seek a compromise, but not optimal, formulation between cooling and lubrication, resulting in both machining efficiency and tool life failing to reach ideal levels.

[0004] Furthermore, to cope with heavy-duty machining, existing technologies typically add extreme pressure additives and solid lubricants. However, extreme pressure additives containing sulfur and chlorine pose environmental and workpiece corrosion problems. While nano-solid lubricants such as graphene and molybdenum disulfide possess excellent lubrication properties, they are prone to agglomeration and sedimentation in water-based machining fluids. This not only makes them difficult to effectively deliver to the micron-level cutting area but can also clog cooling pipes, significantly reducing their effectiveness. A deeper problem lies in the fact that all existing machining fluids play a passive "protective" role, delaying tool wear through lubrication and cooling. Once the tool inevitably experiences microscopic wear under harsh operating conditions, these machining fluids are powerless to help, allowing wear to accumulate until the tool fails and is scrapped. This greatly increases production costs and affects the stability of the machining process. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency drilling and milling composite machining process for pipe pile end plates, which solves the problem that existing metalworking fluids cannot simultaneously meet the contradictory requirements of high-speed cooling and heavy-duty lubrication in drilling and milling composite machining, and lack the ability to actively extend tool life.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a high-efficiency drilling and milling composite machining process for pipe pile end plates. The core of this process lies in the use of a specially formulated intelligent drilling and milling composite machining fluid, and the use of the adaptive response behavior of the machining fluid during the machining process to achieve a breakthrough in process performance.

[0007] The technical solution of the present invention is as follows: A high-efficiency drilling and milling composite machining process for pipe pile end plates, characterized by comprising the following steps: Step A: Prepare and provide an intelligent drilling and milling composite machining fluid.

[0008] The processing fluid is a water-based system, and its components, by mass, include: 2-8 parts of dual rheology-responsive associative polymer, 0.1-1 parts of latent activated core-shell structured nano-lubricant, 0.5-2 parts of tool in-situ self-healing metal-organic precursor, 1-3 parts of chlorine-free phosphorus-based extreme pressure additive, 1-3 parts of auxiliary additives, and the balance being deionized water.

[0009] The dual rheologically responsive associative polymer is a functional polymer with a specially designed molecular structure that possesses two opposite rheological properties: shear thinning and temperature thickening.

[0010] In a specific preparation scheme, the polymer can be prepared through the following steps: First, using a reversible addition-fragmentation chain transfer polymerization method, under nitrogen protection, N-isopropylacrylamide (NIPAM) monomer, a RAFT reagent with hydrophobic long-chain alkyl groups, and an initiator are reacted in an organic solvent to obtain thermosensitive polymer segments with long-chain alkyl tails; subsequently, this product is used as a macromolecular chain transfer agent to perform block copolymerization with a hydrophilic monomer (e.g., acrylic acid) to obtain an amphiphilic block copolymer; finally, the product is purified and the pH value is adjusted. The polymer thus obtained has a "temperature thickening" property due to its thermosensitive segments, while the physical association effect of the hydrophobic long-chain alkyl groups in aqueous solution endows it with a "shear thinning" property.

[0011] The latent activation core-shell structured nano lubricant is a nanoparticle that has undergone surface engineering treatment. It uses a two-dimensional nanomaterial with excellent solid lubrication properties as the "core" and is coated with a "low-temperature water-soluble sacrificial layer" that can be rapidly dissolved in a specific microenvironment as the "shell".

[0012] In a specific preparation scheme, the nano-lubricant can be prepared through the following steps: First, two-dimensional nanomaterials such as boron nitride nanosheets or graphene are ultrasonically dispersed in water; then, a water-soluble polymer (e.g., sodium alginate) and a corresponding crosslinking agent (e.g., calcium chloride) are added to the dispersion, and a gel sacrificial layer is formed in situ on the surface of the two-dimensional nanomaterials by interfacial polymerization; finally, the core-shell structured nano-lubricant is obtained by centrifugation and washing. This sacrificial layer is stable in a conventional aqueous environment, but it rapidly disintegrates upon encountering chemicals that can complex with the crosslinked ions (e.g., phosphate ions), thereby achieving the "activation" and release of the core.

[0013] The aforementioned in-situ self-healing metal-organic precursor is a metal-organic complex that is stable in aqueous solution at room temperature but can undergo tribochemical decomposition under high temperature and high pressure. A preferred example is ammonium tungstate citrate, which has good water solubility and can effectively decompose into highly active tungsten atoms under extreme working conditions at the cutting point.

[0014] Step B: Use the intelligent drilling and milling composite machining fluid to perform drilling and milling composite machining on the pipe pile end plate.

[0015] During the processing, the process of this invention achieves intelligent control from macroscopic cooling to microscopic lubrication and repair through a series of ingenious, step-by-step synergistic physical and chemical effects.

[0016] First, during the circulation and transportation phase of the processing fluid, it is subjected to high shear force as it flows through the pump and pipeline, which activates its shear thinning properties and reduces its viscosity. This enables low-energy, high-flow-rate transportation and allows it to be sprayed into the processing area with high impact force, achieving efficient macroscopic cooling and chip flushing.

[0017] Secondly, after the cutting process begins, the cutting heat generated by the friction between the tool and the workpiece causes the temperature in the machining zone to rise rapidly and exceed the polymer's LCST. At this point, the machining fluid undergoes the following chain reaction: Temperature thickening phase transition: The temperature thickening properties of the polymer are activated, and a high-viscosity dynamic gel film is formed instantaneously at the tool-workpiece interface.

[0018] In-situ activation of lubricants: The formation of the gel film alters the microenvironment of the interface (e.g., local ion concentration), triggering the rapid dissolution of the sacrificial layer on the surface of the latently activated nano-lubricant, thereby "activating" and exposing the highly lubricating two-dimensional nanomaterial core.

[0019] Synergistic enrichment: This high-viscosity gel film not only provides powerful hydrodynamic lubrication, but more importantly, it acts as a physical network to efficiently capture and enrich all functional components, such as newly activated two-dimensional nanomaterials, tool in-situ self-healing metal-organic precursors, and extreme pressure additives, at the friction interface that needs the most protection, forming a multi-component, high-performance composite lubrication and repair system.

[0020] Finally, in micro-regions such as the drill bit tip that are subjected to extreme high temperatures and pressures, when the physical lubrication film may be breached, the highest level of protection and repair mechanism of this invention is activated: Chemical protection: The phosphate ester extreme pressure additives enriched here react with the nascent metal surface to form a chemical protective film, preventing catastrophic adhesion.

[0021] In-situ tool repair: Simultaneously, the metal-organic precursors enriched therein (such as tungsten ammonium citrate) undergo tribochemical decomposition under extreme high temperature and pressure catalysis. The decomposition products (highly reactive tungsten atoms) immediately react in-situ with the tool matrix material (such as carbon in cemented carbide), "growing" a dense, ultra-hard, wear-resistant tungsten carbide (WC) layer at the site of micro-wear on the tool. This process occurs dynamically alongside wear, achieving online repair and strengthening of the tool.

[0022] Furthermore, the process of the present invention also includes the following: after the processing is completed, as the temperature of the cutting zone naturally decreases, the gel film can reversibly recover to a low-viscosity solution state, which facilitates the final cleaning of the workpiece and is beneficial to the recovery and recycling of the processing fluid.

[0023] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention fundamentally solves the inherent contradiction between cooling and lubrication performance in traditional machining fluids. By introducing an associative polymer possessing both "shear-thinning" and "temperature-thickening" rheological properties, the machining fluid exhibits low viscosity during pumping and spraying due to high shear forces, ensuring efficient cooling and flushing; while upon contact with the high-temperature cutting zone, it instantly transforms into a high-viscosity gel film, providing powerful boundary lubrication. This intelligent adaptive characteristic allows a single liquid to exhibit optimal performance under different operating conditions, which is unmatched by traditional cutting fluids.

[0024] 2. This invention constructs a multi-layered, intelligent, and synergistic lubrication and anti-wear system, significantly reducing friction and wear during processing. Its core lies in the fact that the high temperature in the cutting zone not only triggers the phase transition of the polymer but also simultaneously "activates" the previously dormant core-shell structured nano-lubricant. The gel film formed by this phase transition acts like a physical network, efficiently "enriching" and anchoring all functional components, including the newly activated nano-lubricant and extreme pressure additives, at the friction interface, forming a composite lubrication and protective layer that is far more robust and efficient than a simple mixture of components.

[0025] 3. This invention elevates the function of machining fluid from passive protection to active repair, revolutionarily extending tool life. By integrating a tool-in-situ self-healing metal-organic precursor into the formula and utilizing the extreme high temperature and pressure generated by machining itself as a triggering condition, an ultra-hard wear-resistant layer is generated "online" at the site of microscopic wear on the tool. This dynamic balance mechanism of "wearing and repairing simultaneously" can continuously compensate for tool wear, maintain the sharpness of the tool tip, and thus achieve a qualitative leap in tool life.

[0026] 4. This invention significantly improves the machining efficiency of pipe pile end plates, allowing for higher cutting speeds and feed rates. Thanks to the synergistic effect of the excellent cooling, lubrication, and active repair properties mentioned above, the tool remains stable even under more demanding machining parameters, effectively suppressing built-up edge formation and catastrophic wear. This makes it possible to significantly increase material removal rate while ensuring machining quality and tool life, thereby shortening the machining cycle of a single workpiece.

[0027] 5. This invention effectively improves the surface quality of the workpiece and ensures process stability during long-term machining. By forming a stable and efficient composite protective layer between the tool and the workpiece, it effectively suppresses metal surface tearing caused by severe friction and adhesion, thereby achieving lower surface roughness. Simultaneously, the tool's in-situ self-healing mechanism ensures slow performance degradation throughout its service life, avoiding batch-to-batch quality degradation caused by accelerated tool wear, and improving production process stability and yield. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below.

[0030] This invention provides a high-efficiency drilling and milling composite machining process for pipe pile end plates.

[0031] Example 1: Preparation of Intelligent Drilling and Milling Composite Machining Fluid This embodiment provides a high-efficiency drilling and milling composite machining process for pipe pile end plates.

[0032] Step 1: Preparation of the dual rheology-responsive associative polymer. In a 500 mL three-necked flask, 22.6 g of N-isopropylacrylamide monomer, 0.73 g of S-dodecyl-S'-trithiocarbonate, 0.066 g of azobisisobutyronitrile initiator, and 150 mL of dioxane were added as solvent. The reaction was carried out under nitrogen atmosphere in a 70 °C oil bath with magnetic stirring for 12 hours. Subsequently, 7.2 g of acrylic acid monomer was added, and the reaction continued at 70 °C for 8 hours. After the reaction was completed, the product was precipitated in a large amount of petroleum ether, washed repeatedly three times, and then dried in a vacuum drying oven at 40 °C for 24 hours to obtain the P(NIPAM-b-AA)-C12 block copolymer.

[0033] Step 2: Preparation of Latent Activated Core-Shell Structured Nanolubricant. 0.5 g of hexagonal boron nitride nanosheets were added to 200 mL of deionized water and sonicated with a high-power probe for 1 hour to obtain a uniform dispersion. While stirring, 1.0 g of sodium alginate was added to the dispersion. After complete dissolution, 50 mL of a 2% (w / v) calcium chloride solution was added dropwise. After continuous stirring for 30 minutes, the precipitate was collected by centrifugation. The product was washed three times with deionized water to remove excess ions, and finally, the product was freeze-dried to obtain core-shell structured boron nitride nanoparticles.

[0034] Step 3: Final preparation of the intelligent drilling and milling composite machining fluid. In a mixing tank, first add 87.5 parts by mass of deionized water. Start stirring and slowly add 5 parts by mass of the dual rheological response associative polymer prepared in Step 1, stirring until completely dissolved to form a transparent mother liquor. Subsequently, add 0.5 parts by mass of the latently activated core-shell structured nano-lubricant prepared in Step 2 and 1.0 part by mass of tungsten ammonium citrate (as a tool in-situ self-healing metal-organic precursor), and disperse at high speed for 15 minutes until the system is homogeneous. Finally, add 2.0 parts by mass of triethanolamine phosphate (as a chlorine-free phosphorus-based extreme pressure additive) and 4.0 parts by mass of auxiliary additives (including: 0.5 parts of benzotriazole, 1.5 parts of phosphate buffer at pH=9, and 2.0 parts of nonionic surfactant tall oil alcohol polyoxyethylene ether). Mix at low speed for 30 minutes to obtain a homogeneous and stable finished intelligent drilling and milling composite machining fluid.

[0035] Example 2: Preparation of Intelligent Drilling and Milling Composite Machining Fluid This embodiment provides a high-efficiency drilling and milling composite machining process for pipe pile end plates.

[0036] Step 1: The preparation of the dual rheology-responsive associative polymer was carried out using a RAFT polymerization method similar to that in Example 1, but the monomer ratio was adjusted to obtain a lower molecular weight. Specifically, 17.0 g of NIPAM monomer, 0.73 g of RAFT reagent, and 0.066 g of AIBN initiator were reacted in 180 mL of dioxane at 65°C for 10 hours; then 3.6 g of acrylic acid monomer was added, and the reaction was continued for 6 hours. The post-treatment was the same as in Example 1.

[0037] Step 2: The preparation of the latent activated core-shell structured nano-lubricant was carried out using a method similar to that in Example 1. 0.1 g of hexagonal boron nitride nanosheets were dispersed in 100 mL of deionized water, 0.2 g of sodium alginate was added, and the nanosheets were coated with a 1% (w / v) calcium chloride solution. The post-treatment method was the same as in Example 1.

[0038] Step 3: Final preparation of the intelligent drilling and milling composite machining fluid. In a mixing tank, first add 94.3 parts by mass of deionized water. Start stirring and slowly add 2.0 parts by mass of the dual rheological response associative polymer prepared in Step 1. Subsequently, add 0.1 parts by mass of the latently activated core-shell structured nano-lubricant prepared in Step 2 and 0.5 parts by mass of titanium diammonium ethylenediaminetetraacetate (as an in-situ self-healing metal-organic precursor for the tool). Finally, add 1.0 part by mass of oleic acid phosphate ester (as a chlorine-free phosphorus-based extreme pressure additive) and 2.1 parts by mass of auxiliary additives (including pH buffer and rust inhibitor). Mix at low speed for 30 minutes to obtain the finished product.

[0039] Example 3: Preparation of Intelligent Drilling and Milling Composite Machining Fluid This embodiment provides a high-efficiency drilling and milling composite machining process for pipe pile end plates.

[0040] Step 1: The preparation of the dual rheology-responsive associative polymer employed a RAFT polymerization method similar to that in Example 1, but the monomer ratio was adjusted to obtain a higher molecular weight and a stronger associative effect. Specifically: 28.3 g of NIPAM monomer, 0.55 g of RAFT reagent, and 0.049 g of AIBN initiator were reacted in 120 mL of dioxane at 75°C for 15 hours; subsequently, 10.8 g of acrylic acid monomer was added, and the reaction continued for another 10 hours. The post-treatment was the same as in Example 1.

[0041] Step 2: The preparation of the latent activated core-shell structured nano-lubricant was carried out using a method similar to that in Example 1. 1.0 g of functionalized graphene was dispersed in 300 mL of deionized water, 2.0 g of sodium alginate was added, and the mixture was coated with a 3% (w / v) calcium chloride solution. The post-treatment method was the same as in Example 1.

[0042] Step 3: Final Preparation of the Intelligent Drilling and Milling Composite Fluid. In a mixing tank, first add 82.0 parts by weight of deionized water. Start stirring and slowly add 8.0 parts by weight of the dual rheological response associative polymer prepared in Step 1. Subsequently, add 1.0 part by weight of the latently activated core-shell structured nano-lubricant prepared in Step 2 and 2.0 parts by weight of tungsten ammonium citrate. Finally, add 3.0 parts by weight of triethanolamine phosphate and 4.0 parts by weight of auxiliary additives. Mix at low speed for 45 minutes. Due to the high viscosity of the system, ensure uniform mixing to obtain a high-concentration intelligent drilling and milling composite fluid product.

[0043] Comparative Example 1: Compared with Example 1, the difference is that a traditional emulsified cutting fluid formulation is used, without the addition of dual rheology-responsive associative polymers, latent activated core-shell structured nano-lubricants and tool in-situ self-healing metal-organic precursors. Instead, it consists of 15 parts mineral oil, 5 parts emulsifier and surfactant, and the remainder is deionized water.

[0044] Comparative Example 2: Compared with Example 1, the difference is that 5 parts of the dual rheology-responsive associative polymer were replaced with 5 parts of a conventional thickener—hydroxyethyl cellulose. All other components, proportions, and preparation methods remained the same.

[0045] Comparative Example 3: Compared with Example 1, the difference is that in step 3, instead of adding 0.5 parts of the latently activated core-shell structured nano-lubricant prepared in step 2, 0.5 parts of uncoated hexagonal boron nitride nanosheets, identical to the raw materials in step 2, were directly added. All other steps were the same.

[0046] Comparative Example 4: Compared with Example 1, the difference is that in step 3, 1.0 part of ammonium tungstate citrate, which is used as the in-situ self-healing metal-organic precursor for the tool, is not added; the missing mass part is made up by deionized water. All other parts are the same.

[0047] Comparative Example 5: Compared with Example 1, the difference is that the amount of dual rheology-responsive associative polymer added was reduced from 5 parts to 1.0 parts, and correspondingly, the amount of deionized water was increased from 87.5 parts to 91.5 parts. All other aspects were the same.

[0048] Comparative Example 6: Compared with Example 1, the difference is that the amount of dual rheology-responsive associative polymer added was increased from 5 parts to 10.0 parts, and correspondingly, the amount of deionized water was reduced from 87.5 parts to 82.5 parts. All other aspects were the same.

[0049] Comparative Example 7: Compared with Example 1, the difference is that steps 1 and 2 were omitted. In step 3, all the raw materials used to prepare these two components were directly added to water along with the remaining components such as tungsten ammonium citrate and extreme pressure additives for simple physical mixing. The theoretical total mass fraction of each final component remained consistent with that of Example 1.

[0050] Test Example 1: Detailed Experimental Description of Lubrication Performance Comparison Test 1. Test Objective This test aims to quantitatively evaluate the superiority of the machining fluid phase of Example 1 of the present invention over a series of comparative examples in terms of lubrication and friction reduction performance by accurately measuring the spindle torque during the drilling process.

[0051] 2. Experimental Equipment and Materials Test fluids: the intelligent drilling and milling composite machining fluid prepared in Example 1, and the fluids prepared in Comparative Examples 1, 2, 3, and 5.

[0052] Machine tool: A four-axis CNC drilling and milling composite center equipped with a high-precision spindle torque sensor and data acquisition system.

[0053] Workpiece: Q345B steel plate with dimensions of 300mm×200mm×20mm.

[0054] Cutting tools: Brand new, same batch of YG8 carbide drill bits, ø10mm in diameter. A brand new drill bit was used for each test liquid to eliminate errors caused by tool wear.

[0055] Cooling system: The machine tool comes with a high-pressure center water outlet system, with the spray pressure set at 3MPa.

[0056] 3. Experimental Procedure (1) Preparation stage: Securely clamp the Q345B steel plate onto the machine tool worktable. Install the first brand new ø10mm drill bit. Thoroughly clean the machine tool cooling system and inject the machining fluid of Example 1.

[0057] (2) Parameter setting: Write a drilling program in the CNC system and set constant cutting parameters: spindle speed S=1500rpm, feed rate F=200mm / min, drilling depth is 15mm (blind hole).

[0058] (3) Data acquisition: Start the program and, under the condition that the processing fluid is fully sprayed, perform the first drilling on the steel plate. The machine tool data acquisition system automatically records the average spindle torque value during the drilling stage when the drill bit enters the workpiece and stabilizes (drilling depth between 5mm and 12mm).

[0059] (4) Repeat test: Select 5 different locations on the steel plate and repeat the drilling operation in step (3) to obtain a total of 5 torque data. Calculate the arithmetic mean of these 5 data as the final test result of the processing fluid.

[0060] (5) Change the fluid: Drain completely and clean the entire cooling system, pipes and nozzles with a special cleaning agent and deionized water to ensure that there is no fluid residue from the previous run. Replace with a brand new drill bit of the same model.

[0061] (6) Cyclic comparison: Inject the liquid of Comparative Example 1 into the cooling system and repeat steps (3) and (4). Then, repeat steps (5) and (6) with the liquids of Comparative Example 2, Comparative Example 3 and Comparative Example 5 in turn until all liquids have been tested.

[0062] Experimental data Table 1. Comparison of drilling torque test data under different processing fluids

[0063] Experimental Results Analysis and Summary As clearly shown from the test data in Table 1, when drilling with the machining fluid of Example 1 of this invention, the average drilling torque is only 18.3 N·m, significantly lower than all comparative examples. This result intuitively demonstrates the significant advantage of the present invention in lubrication and friction reduction performance, which mainly stems from its unique synergistic lubrication mechanism based on multiple responses. When drilling begins, the high temperature in the cutting zone instantly triggers the "temperature thickening" phase transition of the dual rheological response associated polymer in the machining fluid, forming a high-viscosity dynamic gel protective film at the friction interface between the tool and the workpiece. This gel film not only provides excellent hydrodynamic lubrication itself, but more importantly, it acts as a highly efficient "capturing net," efficiently capturing and enriching the latent activated core-shell structured nano-lubricants that are simultaneously "activated" and released in the system in the cutting zone. This creates a composite lubrication system at the friction interface that is far more robust and efficient than conventional liquids, ultimately resulting in a significant reduction in frictional resistance.

[0064] In stark contrast, the comparative examples exhibited significantly higher torque due to a lack of key innovative design. Comparative Example 2, using a conventional thickener, failed to form a smart, high-strength gel film at high temperatures, resulting in a lubrication effect equivalent to that of ordinary thickened liquids, leading to persistently high torque. Comparative Example 3 directly used uncoated nanoparticles; however, because nanoparticles readily aggregate and settle in water-based solutions, they could not be effectively transported to the cutting zone, thus their lubrication potential was far from being realized, resulting in a torque value much higher than Example 1. Comparative Example 5 demonstrates that even with innovative polymer components, a concentration that is too low (below 2 parts) is insufficient to form a sufficiently dense and robust gel network for effective lubricant enrichment, proving the rationality of the component ratio range. Comparative Example 1, as a traditional emulsion, has a simple lubrication mechanism and cannot cope with harsh drilling conditions, resulting in the highest torque, further highlighting the advanced nature of the present invention.

[0065] In summary, the superior low-torque performance exhibited in Example 1 is not achievable by a single component, but rather the inevitable result of the combined effect of a series of interconnected intelligent response mechanisms: "temperature-triggered phase change," "in-situ lubricant activation," and "multi-component synergistic enrichment." This integrated design allows the lubricant to function at the most critical time, with the highest concentration, and in the most critical location, thereby achieving effective control of cutting friction. This is the core innovation that distinguishes this invention from existing technologies.

[0066] Test Example 2: Detailed Experimental Description of Cooling Performance Comparison Test 1. Test Objective This test aims to evaluate the differences in macroscopic cooling and heat transfer performance of the machining fluid phase of Example 1 of the present invention compared with a series of comparative examples by measuring the peak temperature of the cutting zone in situ during high-speed milling, thereby verifying the advantages brought by its "shear thinning" characteristics.

[0067] 2. Experimental Equipment and Materials Test fluids: the intelligent drilling and milling composite machining fluid prepared in Example 1, and the fluids prepared in Comparative Examples 1, 2, and 6.

[0068] Machine tool: A five-axis CNC machining center equipped with a high-pressure cooling system.

[0069] Workpiece: A Q345B steel plate with dimensions of 300mm × 200mm × 20mm. Multiple micro-holes (0.5mm in diameter) are pre-drilled on the steel plate, with the bottom of the holes 0.5mm from the top surface of the workpiece, for placing thermocouples.

[0070] Cutting tool: Brand new, same batch of ø12mm four-flute carbide end mill.

[0071] Measurement system: Miniature armored K-type thermocouple and matching multi-channel high-speed data acquisition instrument.

[0072] 3. Experimental Procedure (1) Preparation stage: Securely clamp the Q345B steel plate with pre-drilled temperature measuring holes onto the machine tool worktable. Carefully insert a miniature thermocouple into the temperature measuring hole, ensuring that its tip is in close contact with the bottom of the hole. Install a brand new end mill. Thoroughly clean the machine tool cooling system and inject the machining fluid of Example 1.

[0073] (2) Parameter setting: Write a linear milling program in the CNC system. The milling path will pass directly above the thermocouple embedding point. Set the high-speed cutting parameters: spindle speed S=4000rpm, feed rate F=800mm / min, radial depth of cut 3mm, axial depth of cut 0.5mm. Position the cooling nozzles at the cutting area and set the pressure to 4MPa.

[0074] (3) Data Acquisition: Start the data acquisition instrument and then execute the milling program. At the instant the tool passes over the thermocouple, the data acquisition instrument records the rapid temperature change curve. Read and record the peak temperature from this curve.

[0075] (4) Repeat the test: Move to the next pre-made temperature measuring hole and repeat the operation of step (3). A total of 3 independent milling tests were performed, and 3 peak temperature data were recorded. The arithmetic mean of these data was calculated as the final test result of the processing fluid.

[0076] (5) Replace the fluid and cutting tools: Drain the fluid completely and clean the entire cooling system with a special cleaning agent and deionized water. Replace with a brand new end mill of the same model.

[0077] (6) Cyclic comparison: Inject the liquid of Comparative Example 1 into the cooling system and repeat steps (3) and (4). Then, repeat steps (5) and (6) with the liquids of Comparative Example 2 and Comparative Example 6 in turn until all liquids have been tested.

[0078] Experimental data Table 2 Comparison of peak cutting zone temperature under different processing fluids.

[0079] Experimental Results Analysis and Summary The test results in Table 2 clearly show that when using the processing fluid of Example 1, the peak temperature in the cutting zone is only 157.2°C, significantly lower than all comparative examples, demonstrating its superior macroscopic cooling performance. The core of this excellent performance lies in the unique "shear-thinning" characteristic of the dual rheological response associative polymer in this invention. Under the intense shear force of the cooling pump and high-pressure nozzle, the physical associative network formed by the polymer in the aqueous solution is temporarily disrupted, causing a sharp decrease in the overall viscosity of the processing fluid. This low viscosity state endows the liquid with excellent fluidity, enabling it to be delivered to the cutting zone at high flow rates and pressures, forming a strong scouring effect and efficient convective heat transfer, thereby rapidly carrying away heat before it accumulates.

[0080] Conversely, the comparative examples suffered from significant reductions in cooling effect due to fundamental defects in their rheological properties. Comparative Example 2 used conventional hydroxyethyl cellulose as a thickener, which lacks shear-thinning properties, resulting in a consistently high viscosity of the processing fluid, poor flowability, high pumping resistance, and an inability to form an effective cooling jet. Heat accumulated severely in the cutting zone, leading to the highest measured temperature. Although Comparative Example 6 used the polymer of this invention, its concentration was too high (exceeding the upper limit of 8 parts), resulting in an excessively high initial viscosity. Even after some thinning under shear force, its final flow viscosity was still significantly higher than that of the optimally formulated Example 1, thus limiting flow rate and heat transfer efficiency. The traditional emulsion of Comparative Example 1, due to the inherently low specific heat capacity and heat transfer coefficient of its oil phase component, naturally had a weaker cooling capacity than the water-based system, resulting in a temperature much higher than that of Example 1.

[0081] In summary, the superior cooling capability demonstrated in Example 1 is a direct reflection of its "shear-thinning" intelligent response characteristic. The ingenuity of this invention lies in its perfect decoupling and dynamic adaptation of the low viscosity requirements during the macroscopic transport stage with the lubrication requirements of the microscopic cutting zone (achieved through temperature thickening). It is this intelligent transformation capability—presenting a "water" form when cooling is needed and a "gel" form when lubrication is needed—that constitutes the core innovation of this invention, distinguishing it from all statically acting liquids, ensuring effective temperature control during high-load processing.

[0082] Test Example 3: Detailed Experimental Description of Comparative Test of Tool Life and Overall Wear Resistance 1. Test Objective This test aims to compare the number of workpieces that can be processed by the tool before reaching the preset wear limit under different processing fluids by conducting accelerated wear experiments, thereby directly evaluating the decisive advantages of the processing fluid of Embodiment 1 of the present invention in extending tool life and providing comprehensive anti-wear protection.

[0083] 2. Experimental Equipment and Materials Test fluids: the intelligent drilling and milling composite machining fluid prepared in Example 1, and the fluids prepared in Comparative Examples 1, 2, 3, 4, and 7.

[0084] Machine tool: Three-axis CNC drilling center.

[0085] Workpiece: Multiple Q345B steel plates with dimensions of 300mm×200mm×20mm.

[0086] Cutting tool: Brand new YG8 carbide drill bit from the same batch, diameter ø10mm.

[0087] Measuring equipment: A tool microscope with measuring software, used to accurately measure the wear of the drill bit's rake face.

[0088] Cooling system: Standard external overflow cooling, with a flow rate set at 15L / min.

[0089] 3. Experimental Procedure (1) Preparation stage: Securely clamp the Q345B steel plate onto the machine tool worktable. Install the first brand new ø10mm drill bit. Thoroughly clean the machine tool cooling system and inject the machining fluid of Example 1.

[0090] (2) Parameter setting: Set relatively strict drilling parameters in the CNC system to conduct accelerated wear test: spindle speed S=2000rpm, feed rate F=250mm / min, drilling depth is 18mm (through hole).

[0091] (3) Failure Criterion Definition: The failure criterion for the tool is set as the maximum wear on the back face (VBmax) reaching 0.3mm.

[0092] (4) Cyclic testing and measurement: Start the program and drill 20 holes continuously under fully cooled machining fluid conditions. Pause the program, carefully remove the drill bit, and use a tool microscope to measure and record the maximum wear on its flank face.

[0093] (5) Life judgment: If the measured wear is less than 0.3 mm, the drill bit is reinstalled and the next set of 20 holes is drilled, and step (4) is repeated. If the measured wear is equal to or greater than 0.3 mm, the life of the drill bit is determined to be over, and the total number of qualified holes processed at this time is recorded.

[0094] (6) Replacement and cleaning: For each new test liquid, a brand new drill bit from the same batch must be used, and the cooling system must be completely drained and cleaned to ensure that the only variable in the experimental conditions is the processing fluid itself.

[0095] (7) Complete all comparisons: Repeat all the above steps in sequence with the liquid of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 7 until the tool life data of all test objects are obtained.

[0096] Experimental data Table 3 Comparison of tool life test data under different processing fluids

[0097] Experimental Results Analysis and Summary The data in Table 3 irrefutably demonstrate the overwhelming advantage of Embodiment 1 of the present invention in tool protection, with a tool life of up to 417 holes far exceeding that of all comparative examples. This superior performance is a direct reflection of its internally designed multi-layered, intelligent, and collaborative protection system. Under harsh drilling conditions, the machining fluid not only forms a tough physical composite lubricating film on the tool surface through temperature thickening and activation enrichment of nano-lubricants, greatly reducing conventional friction and wear (which explains its superiority over comparative examples 2 and 3), but more importantly, it activates a higher-level protection mechanism, thereby achieving an exponential increase in tool life.

[0098] The test results of Comparative Example 4 are key to understanding the core innovation of this invention. This comparative example includes all innovative components except for the in-situ self-healing precursor for the tool. Although its 263-pore lifespan far exceeds that of traditional fluids, it still lags significantly behind the 417-pore lifespan of Example 1. This gap precisely reveals the decisive contribution of the "in-situ self-healing" mechanism in this invention. Under the extreme high temperature and pressure of drilling, when the physical lubrication film may be instantly breached, the metal-organic precursor enriched in the machining fluid of Example 1 undergoes tribochemical decomposition. Its products react in-situ with the tool matrix, "regenerating" a new ultra-hard wear-resistant layer in the worn micro-region. This dynamic balance of "wearing and repairing simultaneously" enables the tool to continuously resist severe abrasive and adhesive wear, thereby achieving a qualitative leap in lifespan.

[0099] In contrast, the dismal results of the other comparative examples further demonstrate the completeness and advancement of the present invention. The traditional emulsion in Comparative Example 1, lacking effective extreme pressure anti-wear protection, caused the tool to fail rapidly. Comparative Example 7, which simply mixed all the raw materials, failed to form key functional structures (such as associated polymer networks and core-shell nanoparticles), resulting in performance almost identical to traditional liquids. This proves that the unique preparation steps in the present invention are indispensable for achieving its function. Therefore, the ultra-long tool life achieved in Example 1 is not a simple superposition of single functions, but rather the inevitable result of the synergistic effect of its unique, progressive, and interconnected intelligent protection system, from physical lubrication to chemical repair.

[0100] Test Example 4: Detailed Experimental Description of the Comparison Test Between Processing Efficiency and Workpiece Surface Quality 1. Test Objective This test aims to determine the maximum processing efficiency (in terms of material removal rate) that can be achieved when using different processing fluids to ensure excellent surface quality (surface roughness Ra≤1.6μm) of the workpiece, thereby evaluating the comprehensive ability of Embodiment 1 of the present invention to support high-efficiency and high-quality processing.

[0101] 2. Experimental Equipment and Materials Test fluids: the intelligent drilling and milling composite machining fluid prepared in Example 1, and the fluids prepared in Comparative Examples 1 and 7.

[0102] Machine tool: High-rigidity CNC drilling center.

[0103] Workpiece: Multiple Q345B steel plates with dimensions of 300mm×200mm×20mm.

[0104] Cutting tools: Brand new, same batch of ø10mm YG8 carbide drill bits. A brand new drill bit was used for each test liquid.

[0105] Measuring equipment: Portable surface roughness measuring instrument.

[0106] Cooling system: Standard external overflow cooling.

[0107] 3. Experimental Procedure (1) Preparation stage: Securely clamp the Q345B steel plate onto the machine tool worktable. Install the first brand new ø10mm drill bit. Thoroughly clean the machine tool cooling system and inject the machining fluid of Example 1.

[0108] (2) Quality objectives and initial parameters: The acceptance standard for machining quality is set as the surface roughness Ra value of the inner wall of the drilled hole is not greater than 1.6μm. A conservative initial machining parameter is set: spindle speed S=1500rpm, feed rate F=150mm / min.

[0109] (3) Parameter climb test: a. Drill a through hole with a depth of 18mm using the current parameters. b. Remove the workpiece and use a surface roughness measuring instrument to measure the Ra value of the middle section of the inner wall of the hole. c. If the measured Ra value is less than or equal to 1.6μm, the current parameters are considered qualified. Keep the spindle speed constant and increase the feed rate F by 20mm / min, then return to step a. d. If the measured Ra value is greater than 1.6μm, the current parameters are considered to have exceeded the stable machining range. The experiment is terminated, and the previous stable and qualified feed rate is recorded as the "maximum stable feed rate" for this liquid.

[0110] (4) Calculate the maximum material removal rate: Calculate the corresponding maximum material removal rate (MRR) based on the recorded "maximum stable feed rate".

[0111] (5) Replacement and cleaning: For each new test liquid, a brand new drill bit of the same batch must be used, and the cooling system must be completely drained and cleaned.

[0112] (6) Complete all comparisons: Repeat steps (2) to (5) with the liquids of Comparative Example 1 and Comparative Example 7 in turn until the maximum material removal rate data of all test liquids are obtained.

[0113] Experimental data Table 4 Comparison of maximum material removal rates while maintaining a fixed surface quality under different processing fluids

[0114] Experimental Results Analysis and Summary Table 4 clearly reveals the enormous potential of Embodiment 1 of the present invention in supporting high-efficiency precision machining. Its maximum material removal rate of 24.3 cm³ / min far surpasses that of the comparative embodiments. This means that, while ensuring the same excellent workpiece surface quality, the present invention allows the machinist to employ more aggressive cutting parameters, thereby significantly shortening machining time. This advantage stems from the fact that the present invention provides stable and robust comprehensive protection for the cutting zone even under extreme conditions of high speed and heavy load.

[0115] In stark contrast, both Comparative Example 1 and Comparative Example 7 exhibited premature deterioration in machining quality when the machining intensity (feed rate) increased. For the conventional emulsion in Comparative Example 1, a high feed rate meant a dramatic increase in cutting force and heat, causing its single lubrication mechanism to collapse rapidly. This resulted in severe friction and adhesion between the tool and workpiece, tearing of the metal surface, and a sharp deterioration in surface roughness. While Comparative Example 7 contained all the chemical raw materials of this invention, its simple physical mixing failed to form the crucial functional microstructure, thus its performance was only slightly better than the conventional liquid. At high feed rates, the lack of a "shear thinning" effect made it difficult for the high-viscosity liquid to effectively penetrate the cutting zone. More importantly, the absence of a temperature-sensitive polymer network and a latent lubricant carrier prevented intelligent response and synergistic enrichment, ultimately leading to both lubrication and cooling failures.

[0116] In summary, the ability of Example 1 to withstand feed rates as high as 310 mm / min is a result of the synergistic effect of its integrated intelligent response system. During high-intensity machining, "shear thinning" ensures efficient coolant delivery; simultaneously, the surge in cutting heat becomes a strong signal triggering "temperature thickening," "lubricant activation," and "multi-component synergistic enrichment." A high-performance dynamic protective layer is rapidly constructed at the tool-workpiece interface, capable of withstanding high stress while effectively isolating high temperatures, thereby inhibiting built-up edge formation and surface tearing, ensuring excellent surface quality. This ability to maintain superior protection under high loads is the core technological support for the leap in machining efficiency achieved by this invention, demonstrating the advanced nature of its design philosophy.

[0117] Test Example 5: Detailed Experimental Description of Comparative Test on Storage Stability of Processing Fluid 1. Test Objective This test aims to evaluate the effect of the "latent activation" design in the processing fluid of Example 1 of the present invention on improving the dispersion stability of nano-lubricants by monitoring the change in the concentration of nanoparticles in the supernatant of the processing fluid after long-term standing.

[0118] 2. Experimental Equipment and Materials Test fluids: the intelligent drilling and milling composite machining fluid prepared in Example 1, and the fluid prepared in Comparative Example 3.

[0119] Experimental equipment: multiple 100mL graduated glass cylinders and long-handled pipettes.

[0120] Measurement equipment: Ultraviolet-visible spectrophotometer.

[0121] 3. Experimental Procedure (1) Initial state measurement: Take freshly prepared liquids from Example 1 and Comparative Example 3, shake them thoroughly, and take samples immediately. Measure the absorbance at a wavelength of 210 nm (the characteristic absorption wavelength of hexagonal boron nitride) using a UV-Vis spectrophotometer and record it as the initial absorbance.

[0122] (2) Standing test: Pour the liquids of Example 1 and Comparative Example 3 into clean 100mL graduated cylinders, seal them, place them on a vibration-free experimental platform, and let them stand at room temperature for 72 hours. Do not disturb them during this period.

[0123] (3) Sampling after standing: After 72 hours, carefully use a long-handled pipette to draw 10 mL of sample from 2 cm below the liquid surface of each graduated cylinder (i.e., the supernatant area). The sampling process should be extremely slow to avoid disturbing any potential sediment at the bottom.

[0124] (4) Measurement after standing: Immediately use a UV-Vis spectrophotometer to measure the absorbance of the supernatant sample and record it as the absorbance after 72 hours.

[0125] (5) Data processing: The absorbance data obtained at the initial stage and after 72 hours are processed for comparative analysis.

[0126] Experimental data Table 5 Comparison of absorbance of supernatant before and after settling with different processing fluids

[0127] Experimental Results Analysis and Summary Table 5 data visually demonstrates the significant advantage of the present invention in terms of storage stability. After standing for 72 hours, the absorbance of the supernatant of the processing fluid in Example 1 showed almost no change, indicating that the internal nano-lubricating particles remained uniformly dispersed throughout the system. This superior stability directly reflects the "latent activated core-shell structure" design of the present invention. In this design, the hexagonal boron nitride core with solid lubrication function is encapsulated by a hydrophilic sacrificial layer (calcium alginate gel). This outer shell completely alters the surface properties of the particles, enabling them to be well-compatible with aqueous environments, thereby effectively overcoming the aggregation and sedimentation of nanoparticles caused by van der Waals forces.

[0128] In stark contrast, Comparative Example 3, due to the direct use of uncoated, exposed hexagonal boron nitride nanosheets, exhibited extremely poor stability. Despite similar initial concentrations, after 72 hours of settling, the absorbance of its supernatant had significantly decreased to near baseline, indicating that the vast majority of nanoparticles had severely aggregated and settled to the bottom of the graduated cylinder. This clearly reveals that without the surface engineering treatment described in this invention, simply physically mixing nano-lubricants into a water-based liquid cannot create a long-term stable and practically applicable system. The rapid settling of particles means that in actual use, they will largely deposit at the bottom of the reservoir and cannot be pumped to the tool / workpiece interface where they are truly needed.

[0129] Therefore, the innovative design of "latent activation" in this invention is significant not only for the subsequent "activation" release, but also for endowing the entire system with excellent "storage and transport stability." This stability is the foundation and prerequisite for the realization of all subsequent intelligent response functions of this invention. Only by ensuring that the nano-lubricant can be carried to the cutting zone in a stable, latent state can subsequent sophisticated synergistic effects such as "temperature triggering" and "synergistic enrichment" occur. This test strongly demonstrates the necessity and advancement of this design, fundamentally solving the technical problem of the difficulty in stably dispersing high-performance nano-additives in water-based fluids.

[0130] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency drilling and milling composite machining process for a pipe pile end plate, characterized in that, The method comprises the following steps: Step A: preparing and providing an intelligent drilling and milling composite machining fluid, which comprises, in terms of mass fraction, the following components: a double rheological response associated polymer: 2-8 parts; a latent activation type core-shell structure nanometer lubricant: 0.1-1 part; a tool in-situ self-repairing metal organic precursor: 0.5-2 parts; a chlorine-free phosphorus-based extreme pressure additive: 1-3 parts; auxiliary additives: 1-3 parts; and the balance of deionized water; wherein the double rheological response associated polymer has shear thinning and temperature thickening properties; the latent activation type core-shell structure nanometer lubricant has a two-dimensional nanometer material as a core and a low-temperature water-soluble sacrificial layer as a shell; and the tool in-situ self-repairing metal organic precursor can be decomposed under the action of friction chemistry and reacts with the tool surface to form a wear-resistant layer; Step B: using the intelligent drilling and milling composite machining fluid to perform drilling and milling composite machining on the pipe pile end plate, in the cutting zone, using cutting heat to trigger the double rheological response associated polymer to undergo temperature thickening phase transition, which in turn triggers the activation of the latent activation type core-shell structure nanometer lubricant, and cooperatively enriches various lubricating and repairing components to form a composite lubricating and repairing system; and under extreme working conditions, using the tool in-situ self-repairing metal organic precursor to perform in-situ repair on the tool wear area.

2. The process according to claim 1, characterized in that, The step A specifically comprises: dissolving the double rheological response associated polymer in deionized water to form a mother liquor, then dispersing the latent activation type core-shell structure nanometer lubricant and the tool in-situ self-repairing metal organic precursor in the mother liquor, and finally adding the chlorine-free phosphorus-based extreme pressure additive and the auxiliary additives and mixing uniformly.

3. The process of claim 1, wherein, The step B comprises pumping and spraying the machining fluid to the machining area through a nozzle, and in the pumping process, the machining fluid activates its shear thinning property due to the shear force, thereby reducing the flow viscosity.

4. The process of claim 1, wherein, The formation of the composite lubricating and repairing system starts from the temperature thickening phase transition of the machining fluid when the temperature in the cutting zone rises and exceeds the lower critical solution temperature of the double rheological response associated polymer, forming a high-viscosity dynamic gel film.

5. The process of claim 4, wherein, The activation of the latent activation type core-shell structure nanometer lubricant is achieved by triggering the dissolution of the sacrificial layer on its surface through the interface microenvironment change caused by the formation of the high-viscosity dynamic gel film, thereby exposing the two-dimensional nanometer material core with high lubricating activity.

6. Process according to claim 4 or 5, characterized in that, The cooperative enrichment is achieved by capturing and concentrating the activated two-dimensional nanometer material core, the tool in-situ self-repairing metal organic precursor and the chlorine-free phosphorus-based extreme pressure additive in the tool-workpiece interface by the high-viscosity dynamic gel film.

7. The process of claim 1, wherein, The in-situ repair of the tool is achieved by the friction chemical decomposition of the enriched metal organic precursor under the extreme high temperature and high pressure at the cutting point, and the in-situ reaction of the decomposition products with the tool base material to form a metal carbide or intermetallic compound wear-resistant layer.

8. The process of claim 1, wherein, The two-dimensional nanometer material is selected from boron nitride nanosheet, graphene, molybdenum disulfide, tungsten disulfide or any combination thereof.

9. The process according to claim 1 or 7, characterized in that, The in-situ self-repairing metal organic precursor of the tool is a water-soluble organic acid salt or alcoholate complex containing at least one of tungsten, titanium, molybdenum or chromium.

10. The process of claim 1, wherein, The process further comprises step C: after the machining is completed, as the temperature of the cutting area is lowered to below the lower critical solution temperature of the polymer, the formed gel film reversibly returns to a low-viscosity solution state, facilitating cleaning of the workpiece and recycling of the machining liquid.

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