Gradient composite material cutter blade wear damage inhibition and wear control method

Abstract

The invention discloses a gradient composite material cutter blade abrasion damage restraining and abrasion control method, and belongs to the technical field of superhard cutter manufacturing and precision machining. The method comprises the following steps: S1, providing a cutter blank which is formed by laser additive manufacturing and has a gradient structure; s2, a slow feeding grinding strategy is adopted, grinding parameters are optimized, and profile grinding is conducted on the green body; s3, the ground cutting edge is subjected to laser passivation polishing or controllable sand blasting passivation treatment, so that defects are eliminated, and a target blunt circle radius is formed; and S4, cleaning, detecting and verifying the cutting performance. In order to solve the problems of hard phase crushing, grinding burn, coating falling and the like in gradient composite material cutter sharpening, low-damage and high-quality manufacturing of a cutter cutting edge is achieved through a synergistic process chain of optimized grinding, precise passivation and parameter regulation and control.

Description

Technical Field

[0001] This invention relates to the field of superhard tool manufacturing and precision machining technology, specifically to a grinding process for superhard coated tools made of gradient composite materials, which aims to suppress machining damage during grinding, optimize the cutting edge quality of the tool, and improve its wear resistance and chipping resistance. Background Technology

[0002] Gradient composite superhard coated cutting tools, such as ceramic-ceramic (e.g., TiCp / Al2O3-ZrO2) and metal-ceramic (e.g., TiC / iron-based alloy) gradient material tools, have become key tools in high-end precision machining fields due to their excellent wear resistance, high-temperature stability, and high hardness. Related research indicates that after laser additive manufacturing (e.g., laser cladding, laser-directed energy deposition), these materials often exhibit microstructure inhomogeneity and interfacial bonding between hard particles (e.g., TiC, SiC) and the matrix in the cutting edge region.

[0003] However, due to their high hardness and inherent brittleness, these materials are highly susceptible to various forms of damage during grinding (especially when grinding complex spatial curved surfaces such as helical grooves and flank faces). Studies have confirmed that the main forms of damage include: breakage and spalling of hard reinforcing particles, microcracks at the interface between the matrix and the particles, and "grinding burns" caused by the high temperature in the grinding zone. The latter severely weakens the adhesion between the coating and the matrix, leading to coating peeling. These damages severely compromise the cutting edge integrity and surface / subsurface quality of the tool, directly resulting in decreased cutting performance and shortened tool life. Experimental data show that improper grinding can generate numerous pits and cracks on the surface of gradient ceramics, deteriorating the surface roughness (Sa) value.

[0004] Existing grinding technologies are mostly designed for homogeneous cemented carbide or ceramic tools, improving surface roughness by adjusting single parameters such as grinding speed and depth. However, for composite materials with gradient variations in composition, microstructure, and properties, this simple adjustment is insufficient to coordinate the differences in machinability between different regions within the material (such as the hard particle-rich region and the matrix region), and cannot systematically solve problems such as uneven stress distribution, interface protection, and thermal damage suppression. For example, conventional speed grinding easily induces brittle fracture in the hard particle region, while potentially generating a plastic deformation layer in the matrix region; traditional mechanical passivation (such as sandblasting) can form a blunt rounded surface, but impact can easily introduce new micro-defects or cause the gradient coating to peel off due to stress concentration.

[0005] Therefore, there is an urgent need to develop a systematic method for suppressing grinding damage and controlling wear based on the characteristics of gradient composite materials, so as to achieve precise and low-damage manufacturing of high-performance tool cutting edges. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing technologies and provide a method for suppressing grinding damage and controlling wear of gradient composite material cutting tools. This method effectively suppresses grinding damage by integrating optimized grinding processes, precision passivation technology, and systematic parameter control, resulting in high-quality, high-performance cutting edges. This significantly improves the wear resistance, chipping resistance, and service life of gradient composite material cutting tools.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for inhibiting grinding damage and controlling wear of gradient composite material cutting tools includes the following steps performed sequentially: Step S1: Gradient tool blank preparation and pretreatment This provides a pre-prepared superhard coated tool blank with a predetermined gradient structure, manufactured using laser additive manufacturing technologies such as laser cladding, laser-directed energy deposition (LDED), or selective laser melting (SLM). The blank has undergone preliminary geometric shaping but has not yet undergone precision edge grinding and passivation. The gradient structure includes, but is not limited to, the following two types: Ceramic-ceramic gradient materials: For example, composite materials with Al2O3, ZrO2 or their eutectic ceramics as the matrix and TiC, SiC, WC or diamond particles as the reinforcing phase, wherein the volume fraction or weight percentage of the reinforcing phase changes continuously or stepwise along the thickness direction of the tool coating or a specific functional direction (e.g., gradually increasing from 0% to 50%).

[0008] Metal-ceramic gradient materials: For example, composite materials with Fe-based, Ni-based or Co-based alloys as the binder phase or metal matrix, and TiC, WC or other carbides as ceramic reinforcing phases, where the concentration of the ceramic phase decreases in a gradient from the coating surface to the interface with the tool matrix, in order to achieve the best match between hardness and toughness.

[0009] Before subsequent sharpening, the blank must be cleaned to remove surface deposits.

[0010] Step S2: Optimizing the grinding process based on gradient material properties This step is a grinding process designed for the machinability characteristics of gradient composite materials, with the goal of efficiently removing material while minimizing machining damage.

[0011] Grinding strategy selection: For tools with helical grooves and complex profiles, the creep-feed grinding strategy is preferred. Its characteristics include a larger depth of cut (compared to ordinary reciprocating grinding) and an extremely low table feed rate. This strategy increases the contact arc length between the grinding wheel and the workpiece, reduces the thickness of undeformed chips per abrasive grain, and facilitates the removal of hard and brittle gradient ceramic materials in a "plastic domain" or quasi-plastic manner, thereby reducing brittle fracture and crack propagation.

[0012] Key grinding parameter optimization: The optimal combination of grinding parameters for a specific gradient material system is determined through systematic process experiments (preferably orthogonal experimental design). The optimization objectives are to minimize grinding force, minimize surface roughness, and eliminate visible grinding burns. Experimental factors include at least: Grinding wheel linear velocity (V_s): directly affects grinding force, grinding temperature, and material removal mechanism. For gradient ceramic materials, higher velocity helps reduce the load on individual abrasive grains and grinding force. Based on previous orthogonal experimental studies, the preferred range for grinding wheel linear velocity is 20-60 m / s, more preferably 24-32 m / s.

[0013] Workpiece axial feed rate (V_w): Under slow feed grinding, V_w is usually low. The optimal value needs to be found experimentally to ensure efficiency without causing chatter or excessive thermal damage. The preferred range for workpiece axial feed rate is 8.33 × 10⁻⁶. -4 m / s to 1.58×10 - ³m / s.

[0014] Grinding depth (a_p): Set separately for rough grinding and finish grinding stages. Rough grinding can use a larger depth of cut to improve efficiency; finish grinding uses a smaller depth of cut to improve surface quality. Preferably, the rough grinding depth is 4-10 μm and the finish grinding depth is 1-4 μm.

[0015] Grinding wheel grit size: Dynamically selected based on the machining stage. For roughing or deep-cut grinding of gradient materials, coarser grit (e.g., D64-D100) diamond wheels are recommended. These offer greater chip space, reducing clogging, and lower grinding force, thus minimizing overall force and heat load. For finishing, finer grit (e.g., D46 or finer) wheels are used to achieve lower surface roughness and more precise geometry.

[0016] Optimization experiments show that grinding wheel grit size is the most influential factor on the surface roughness of spiral groove grinding, followed by grinding wheel linear speed, while workpiece feed speed has the least influence.

[0017] Active suppression of grinding thermal damage: This is crucial for protecting the interface of gradient coatings. Measures include prioritizing high wheel linear speed combinations that reduce grinding forces during parameter optimization; Design and apply an efficient cooling system to ensure that sufficient, pressure-adjustable coolant (such as specialized grinding fluid) can be precisely sprayed onto the grinding arc area, especially the heat-prone "groove face" area; the coolant must have good lubrication, cooling and cleaning properties.

[0018] By monitoring processes (such as acoustic emission and power monitoring) or conducting post-experimental tests (such as corrosion methods to show burns), ensure that optimized process parameters can keep the temperature in the grinding zone below the threshold that prevents the gradient coating from deteriorating.

[0019] Step S3: Precision passivation and strengthening treatment of the cutting edge Even after grinding, the cutting edge still has microscopic unevenness and defects. This step aims to "finish" and "strengthen" it.

[0020] Passivation process options: Two precision passivation technologies are available that can be used individually or sequentially: Option A: Laser Passivation Polishing: This is a non-contact, high-precision "cold processing" method. It employs a dual-laser beam system, for example, using a continuous infrared laser to gently preheat a localized area to reduce brittleness, followed by precise ablation removal using a picosecond or femtosecond ultraviolet laser. By precisely controlling the laser parameters (wavelength: 355nm / 1064nm; power: 10-100W adjustable; pulse frequency; scanning speed: 100-1000mm / s; spot overlap rate: 30%-70%; scanning path), it can selectively remove burrs and micro-notches from the cutting edge, similar to "micro-engraving," and polish the surface to achieve a mirror or near-mirror finish in the cutting edge area. This significantly reduces surface roughness and introduces almost no heat-affected zone or mechanical stress.

[0021] Option B: Controlled Sandblasting Passivation: This is a relatively low-cost and easy-to-implement mechanical passivation method. The key is "controllable," meaning precise control over the traditional sandblasting process. A sandblasting device with precisely adjustable air pressure (0.1-0.5 MPa) is used, selecting fine abrasives with uniform particle size (e.g., 100-800 mesh). Strict control is maintained over the sandblasting time, angle (avoiding vertical impact, usually at a certain angle to the cutting edge), and distance. The aim is to smooth the microscopic contour of the cutting edge through the uniform, slight impact of countless tiny abrasive particles, forming a uniform blunt radius, while cleaning the surface without causing impact-induced detachment of hard particles or damage to the substrate. Preferably, the abrasive is diamond, alumina, or silicon carbide, with a particle size preferably of 200-400 mesh; the sandblasting time is controlled between 10-60 seconds based on the target blunt radius, preferably within 30 seconds; the sandblasting angle is an acute angle relative to the tangent direction of the cutting edge.

[0022] Passivation parameter optimization and blunt circle radius control: The goal of passivation is not only to achieve smoothness, but also to obtain an optimal blunt circle radius (rε) on the cutting edge. See also Figure 8a , Figure 8b and Figure 8cOrthogonal experiments were conducted to investigate the influence of passivation time and equipment motion parameters (such as the revolution / rotation speed and the ratio of forward to reverse rotation time of the rotary passivation machine) on the final blunt circle radius. Based on the tool application scenario (roughing, finishing, intermittent cutting, etc.) and coating thickness, target blunt circle radius ranges were designed: light blunt circle (approximately 10-30 μm, for finishing), medium blunt circle (approximately 30-80 μm, general-purpose), and heavy blunt circle (approximately 80-150 μm, for heavy-duty intermittent cutting). Through parameter optimization, stable and controllable blunt circle radii were achieved.

[0023] Step S4: Post-processing and overall performance verification This is the final step to ensure the quality of the process and the final performance of the cutting tools.

[0024] Cleaning and drying: After passivation, thoroughly clean the tool to remove all abrasive residue, coolant or contaminants, and then dry it completely.

[0025] Comprehensive quality inspection: Utilizing multiple instruments to perform non-destructive or minimal-destructive testing on the cutting edge. Morphological observation: Use a super depth-of-field 3D microscope to observe the macroscopic morphology of the cutting edge and whether there are any chips or defects.

[0026] Microscopic analysis: Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were used to examine the microstructure of the cutting edge, the bonding state between hard particles and the matrix, and the presence of microcracks or coating abnormalities.

[0027] Roughness measurement: The surface roughness (Sa, Ra value) near the cutting edge is quantitatively measured using a white light interferometer or confocal microscope.

[0028] Blunt radius measurement: The actual blunt radius of the cutting edge is measured using a profilometer or a special tool detector.

[0029] Ultimate verification of cutting performance: The tool was mounted on a standard machine tool, and cutting tests were conducted to simulate actual working conditions. Chipping resistance test: 45# steel bar with annular groove was used, and interrupted turning was performed with cutting parameters set (e.g., Vc=250m / min, ap=1.0mm, f=0.2mm / rev). The state of the tool edge after ≥1300 impacts was recorded, requiring no macroscopic chipping visible to the naked eye.

[0030] Wear resistance test: 35CrMo alloy steel bar was selected and continuously machined under the same parameters. The width of the wear band on the flank face (VB value) was monitored, and the cutting time taken to reach the critical wear value of 0.2mm was recorded. The requirement was ≥40 minutes.

[0031] Compared with the prior art, the present invention has the following significant advantages: 1. Significant Damage Suppression: Through optimized creep-feed grinding strategy and refined process parameter matching, the brittle fracture and spalling of the hard phase and the generation of grinding burns in gradient composite materials are effectively reduced during grinding, improving the integrity and subsurface quality of the machined surface. Experiments show that after optimized grinding, the surface roughness Sa of gradient ceramics can be reduced to about 0.6 μm.

[0032] 2. Excellent cutting edge quality: Combining high-energy laser polishing or controlled sandblasting passivation technology, microscopic defects on the cutting edge can be precisely and controllably removed, forming a uniform and stable ideal blunt radius, which significantly improves the macroscopic strength and microscopic resistance to chipping of the cutting edge. Laser polishing can significantly improve the surface quality of the cutting edge; for example, in specific implementations, it can reduce the roughness Ra of the cutting edge area by approximately 44%.

[0033] 3. Enhanced Overall Tool Performance: Gradient composite material tools treated with the method of this invention maintain high hardness and wear resistance while exhibiting enhanced impact toughness and fatigue resistance, resulting in a significantly extended service life. Cutting verification shows that tools treated with this method exhibit excellent performance. For example, under specific cutting parameters (Vc=250m / min, ap=1.0mm, f=0.2mm / rev), the impact resistance during interrupted turning of grooved 45# steel can exceed 2300 cycles; for continuous turning of 35CrMo alloy steel, the cutting time can exceed 40 minutes when the flank wear reaches 0.2mm.

[0034] 4. Strong process adaptability and operability: This invention provides a systematic method framework and parameter optimization path, which can be flexibly adjusted according to different gradient material systems (ceramic matrix / metal matrix), tool geometry and performance requirements, and has good universality and engineering application prospects. Attached Figure Description

[0035] Illustration: Figure 1 This is an overall process flow diagram of the method described in this invention; Figure 2 A comparison chart of various performance parameters between conventional reciprocating grinding and creep-feed grinding; Figure 3 The graph shows the variation of surface roughness between reciprocating grinding and creep-feed grinding under the same material removal rate. Figure 4 This is a schematic diagram of the overall technical solution for laser passivation and polishing of the present invention; Figure 5 These are before-and-after photos of the appearance of the cutting tool of this invention before and after laser polishing; Figure 6 This is a comparison image of the surface roughness of the cutting tool before and after laser polishing. Figure 7aThis is a diagram of the orthogonal experimental scheme for optimizing grinding parameters in this invention; Figure 7b The effect curves of various factors (grind wheel linear velocity, workpiece feed rate, and grinding wheel grit size) on axial grinding force in the orthogonal experiment for grinding parameter optimization of this invention are shown. Figure 7c This is a graph showing the effect curves of various factors on the grinding force ratio in the orthogonal experiment for optimizing grinding parameters according to the present invention. Figure 7d This is a graph showing the effect of various factors on surface roughness (Ra) in the orthogonal experiment for optimizing grinding parameters according to the present invention. Figure 8a The orthogonal experimental factor level table for the passivation parameter optimization of this invention (passivation time, forward / reverse rotation time ratio, revolution speed, and rotation speed); Figure 8b The orthogonal experimental scheme and results table for optimizing the passivation parameters of this invention are as follows; Figure 8c The graph shows the relationship between the passivation time, the ratio of forward and reverse rotation time, and the radius of the passivation circle in the orthogonal experiment for optimizing the passivation parameters of this invention. Figure 9 These are typical SEM microscopic images of the cutting edge of the tool in the embodiments of the present invention; Figure 10a This is a schematic diagram of the anti-breakage test setup for the present invention; Figure 10b This is a diagram showing the experimental results of the anti-breakage test of the present invention; Figure 10c This is a schematic diagram of the wear resistance test setup for the present invention; Figure 10d The figure shows the results of the wear resistance test of this invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] like Figure 1 As shown, an embodiment of the present invention provides a method for suppressing grinding damage and controlling wear of gradient composite material cutting tools, which involves performing the following steps in sequence: S1. Provide an ultrahard coated tool blank with a gradient structure, wherein the gradient structure is formed by laser additive manufacturing technology; S2. The tool blank is subjected to profile grinding using a slow feed grinding strategy, and the grinding parameter combination suitable for gradient material properties is determined through process experiments. The parameter combination includes at least grinding speed, workpiece feed speed and grinding depth. S3. Perform precision passivation treatment on the grinding tool edge, wherein the passivation treatment is laser passivation polishing and / or controlled sandblasting passivation, in order to eliminate micro-defects on the edge and form a target blunt circle radius; S4. Clean, inspect, and verify the cutting performance of the passivated cutting tool.

[0038] In this invention, the integral gradient composite material tool is ground using a five-axis CNC tool grinder, and all finishing processes can be completed in a single setup. The grinding process of the integral gradient composite material tool mainly includes four steps: grinding the helical groove (helix angle), grinding the peripheral cutting edge back face (peripheral tooth back angle), grinding the chisel edge (chip groove), and grinding the end face (end tooth back angle). Different tool structures require different grinding types, and therefore different types of grinding wheels are selected. For example... Figure 2 A comparison chart of performance parameters for conventional reciprocating grinding and creep-feed grinding is shown, indicating that creep-feed grinding features large depth of cut, low workpiece feed rate, and a longer contact arc length, making it particularly suitable for profile grinding with large material allowances. Generally, reducing the workpiece feed rate is a very feasible method to improve the surface roughness of ground surfaces. However, for creep-feed grinding, the effect of improving surface roughness by reducing the material removal rate is not significant. Figure 3 As shown, under the same material removal rate, the surface roughness Ra value of reciprocating grinding decreases significantly with decreasing feed rate; while the surface roughness Ra value of creep feed grinding remains relatively stable and low at different feed rates. It can be seen that reducing the workpiece feed rate can improve the surface roughness of the workpiece in reciprocating grinding, while it remains basically at the same level in creep feed grinding.

[0039] Specifically, the sharpening method of the present invention will be described below with reference to a specific cutting tool: Example 1: Integral grinding of TiCp gradient-enhanced Al2O3-ZrO2 eutectic ceramic end mills This embodiment uses an Al2O3-ZrO2 eutectic ceramic four-flute end mill blank prepared by laser-directed energy deposition (LDED) with a TiCp content that varies in a stepwise gradient from 0 wt.% to 50 wt.% as the processing object.

[0040] The billet is in a basic cylindrical shape and has a cutting edge length, but the spiral groove, the back angle of the peripheral cutting edge, and the end cutting edge have not been finely machined. The surface is in a deposited state and is relatively rough.

[0041] Process objective: To complete the precision grinding and passivation of all cutting edges, so that the tool can be brought to a state where it can perform high-performance milling.

[0042] The specific steps for sharpening a cutting tool are as follows: S1. Pretreatment: Use an ultrasonic cleaner to clean the blank with acetone and anhydrous ethanol in sequence to remove surface oil and loose attachments, and then dry it for later use.

[0043] S2. Optimize grinding process: Equipment and grinding wheels: The process is carried out on a five-axis CNC tool grinder (such as ANCA or WALTER series). According to the instructions of this invention, two types of diamond grinding wheels are prepared: D80 grit (for rough grinding of spiral grooves and large allowance removal) and D46 grit (for fine grinding of all cutting surfaces and final shaping).

[0044] The specific process of parameter optimization experiment (orthogonal experiment): For this specific TiCp / Al2O3-ZrO2 gradient ceramic material, an L9(3)2 orthogonal experimental design was performed. 4 Orthogonal experiment. The four factors and their levels are as follows: A (grinding wheel linear velocity V_s: Level 1 is 16 m / s, Level 2 is 24 m / s, Level 3 is 32 m / s), B (workpiece axial feed rate V_w: Level 1 is 8.33 × 10⁻⁶ m / s). -4 m / s, Level 2 is 1.08×10 - ³ m / s, level 3 is 1.33 × 10 - The evaluation criteria are: C (rough grinding depth a_p: 4μm for level 1, 6μm for level 2, and 8μm for level 3; fine grinding depth is fixed at 2μm), and D (rough / fine grinding wheel combination: D80 / D46 for level 1, D100 / D46 for level 2, and D64 / D46 for level 3). The evaluation indicators are the surface roughness (Sa) of the helical groove after grinding, the axial grinding force (Fz), and the presence of burn spots observed under a 100x microscope.

[0045] Press L9(3) 4 An orthogonal array is used to arrange 9 groups of experiments (e.g.) Figure 7a (As shown). Sa and Fz were measured after each group of experiments. Range analysis was performed on the results. The analysis revealed (as shown) Figure 7b , Figure 7c , Figure 7d As shown): For surface roughness Sa, the order of the ranges of each factor is: grinding wheel grit size (D) > grinding wheel linear velocity (A) > grinding depth (C) > workpiece feed rate (B). This indicates that grinding wheel grit size is the most important factor affecting surface quality. For grinding force Fz, the grinding wheel linear velocity (A) has the most significant impact. Considering all indicators, the optimal level combination is determined to be: A2 (V_s=24 m / s), B1 (V_w=8.33×10). -4 The grinding speeds were C2 (a_p rough grinding = 6μm) and D1 (grinding wheel combination D80 / D46). Under this combination, the Sa value measured in the verification test was the lowest (approximately 0.6μm), the grinding force was moderate, and no visible burns were observed.

[0046] Grinding is performed: Rough grinding of spiral grooves: Replace with a D80 grinding wheel, use the slow feed mode, and set V_s=24m / s, V_w=8.33×10 -4 At a speed of m / s and a_p = 6μm, the basic shape of the spiral groove was obtained through layered grinding. The coolant pressure was set to 1.5MPa, and the flow rate was sufficient.

[0047] Fine-grind all surfaces: Replace with a D46 grinding wheel. First, fine-grind the spiral grooves, adjusting the parameters to V_s=30m / s (slightly increased to further improve surface quality), V_w=8.33×10 -4 m / s, a_p=2μm. Then, the peripheral clearance angle, end clearance angle, etc. are ground sequentially, using similar optimized parameters, but the feed rate is finely adjusted according to the contact conditions.

[0048] Thermal damage inspection: Immediately after grinding, the surface of the spiral groove is lightly corroded with a specific etchant (such as hot pickling). Observation under an optical microscope confirms that no discoloration or etching differences caused by burns are found in key areas such as the groove rake face, indicating that thermal control is effective.

[0049] S3. Precision passivation treatment: Given the extremely high hardness of ceramic materials and the high requirements for surface finish, this example selects a laser passivation and polishing solution (such as...). Figure 4 (As shown).

[0050] Equipment: A self-built dual-laser-beam polishing workstation is used. One beam is a continuous fiber laser with a wavelength of 1064nm and a maximum power of 50W (for local preheating), and the other beam is an ultraviolet picosecond laser with a wavelength of 355nm and an average power of 30W (pulse width ~10ps, for fine removal).

[0051] Fixture: A spring collet fixture designed specifically for end mills is used and mounted on a rotary table that can be precisely indexed to ensure that the laser beam can scan all cutting edges evenly.

[0052] Parameter determination and polishing: First, without turning on the 1064nm laser, a single-factor experiment was conducted on the sample edge using only a 355nm laser to determine the power threshold (25W in this example) that does not produce microcracks and the effective scanning speed range.

[0053] During the formal polishing process, all four cutting edges are treated sequentially. The process parameters are set as follows: 355nm laser power 22W, 1064nm laser auxiliary power 5W (with slight preheating), scanning speed 600mm / s, spot overlap rate 55%, and the scanning path is repeated back and forth along the cutting edge direction, three times. The entire process is carried out under nitrogen protection to prevent oxidation.

[0054] Effect: After polishing, the cutting edge visibly exhibits a brighter metallic luster (e.g., ...). Figure 5 As shown). The surface roughness Ra value of the rake face near the cutting edge was measured using a confocal microscope, and it decreased from approximately 2.173 μm after grinding to approximately 0.879 μm (as shown). Figure 6 As shown in the figure, the decrease was approximately 60%.

[0055] S4. Post-processing and verification: Cleaning: Use an ultrasonic cleaner to clean the polished milling cutter with ethanol to thoroughly remove any possible adhering substances.

[0056] Comprehensive quality inspection: Morphology and Defect Inspection: All cutting edges were observed using a super depth-of-field 3D microscope (such as Keyence VHX-7000) at 200-500x magnification to confirm that the cutting edge was continuous and free of macroscopic chipping, microcracks, and obvious coating peeling. Stress concentration areas such as the junction of the cutting edge and the spiral groove were specially inspected.

[0057] Microstructure and composition analysis: The cutting edge was observed at high magnification using a field emission scanning electron microscope (SEM, such as a Hitachi SU5000). Figure 9 As shown, the key points to observe are: The interfacial bonding between TiCp particles and the Al2O3-ZrO2 eutectic matrix was confirmed, and no interfacial separation or cracks caused by grinding or polishing were found.

[0058] The morphology of the polished area on the cutting edge shows a typical smooth surface formed by laser ablation, without abnormal grain growth or thermal cracks.

[0059] Roughness and profile measurement: The three-dimensional surface morphology of the helical groove surface after precision grinding and the rake face of the cutting edge after laser polishing was measured using a white light interferometer (such as Taylor Hobson CCI). The Sa value of the helical groove surface was measured to be approximately 0.58 μm, meeting the requirements for precision machining. The Ra value of the polished cutting edge area was stable at around 0.9 μm.

[0060] Blunt circle radius measurement: Using a high-precision optical profilometer or a dedicated tool pre-adjustment measuring instrument, the blunt circle radius rε of the four cutting edges is measured to be within the range of 12-18μm, with good uniformity, which meets the design requirements of lightweight blunt circles.

[0061] Ultimate verification of cutting performance: Wear resistance test: End milling experiments were conducted on a vertical machining center. Workpiece material: quenched and tempered 35CrMo alloy steel plate (hardness ~300HB). Cutting parameters: Vc=180m / min, fz=0.08mm / tooth, ap=5mm, ae=12mm (radial cutting width is 60% of tool diameter), dry cutting to accelerate wear. Experimental results show that when the total cutting path length reaches 45 meters, the average wear VBmax on the tool flank is approximately 0.18mm, still below the failure criterion of 0.2mm, demonstrating excellent wear resistance.

[0062] Observation of chipping resistance: In the later stage of wear resistance test and in the special interrupted milling test (side milling of square steel with keyway), no chipping of the cutting edge visible to the naked eye or under a microscope occurred.

[0063] Example 2: Preparation of the cutting edge of a TiC particle-reinforced iron-based gradient-coated indexable lathe insert This embodiment focuses on the finishing of the cutting edge of a TiC particle-reinforced iron-based gradient-coated indexable insert (CNMG120408 standard shape) prepared by laser cladding onto a cemented carbide substrate.

[0064] Preform condition: The insert substrate is commercial cemented carbide. A functionally graded coating (approximately 0.5 mm thick) with TiC content gradually decreasing from the surface to the interior is prepared by laser cladding on the surface requiring coating. After coating, the insert needs to be ground to form precise geometry and a sharp initial cutting edge.

[0065] Process objective: To produce cutting edges with high strength and high resistance to spalling, suitable for rough machining and interrupted cutting of steel.

[0066] S1. Pre-treatment: Use professional cleaning agents and ultrasonic cleaning to clean the blades and remove residual coolant and grinding debris after grinding.

[0067] S2. Optimize grinding process: Equipment and grinding wheels: The process was carried out on a precision surface grinder and a dedicated cutting tool sharpening machine. Since the coating is a metal matrix composite material, its hardness is lower than that of the ceramic in Example 1, but its toughness requirement is high. Therefore, resin-bonded diamond grinding wheels were selected, with grit sizes of D120 (for profile grinding) and D20 (for final edge grinding).

[0068] Parameter characteristics: Considering the characteristics of metal-ceramic gradient coatings, the grinding strategy prioritizes efficiency while controlling grinding heat to prevent coating "burning" (reduced adhesion). A slightly lower grinding wheel linear speed (V_s=20m / s) is used in conjunction with more sufficient coolant. Experiments have shown that with parameters of V_w=0.5m / min and a_p=0.01mm (fine grinding), a smooth cutting edge surface without signs of burning can be obtained.

[0069] S3. Precision passivation treatment: Considering the economic efficiency of mass production of cutting blades, and the relatively good resistance of coating materials to mechanical impact, this example chooses the controlled sandblasting passivation solution.

[0070] Equipment and abrasive: A CNC sandblasting machine is used, and the working air pressure can be precisely adjusted between 0.1-0.8MPa. The abrasive selected is 320-mesh brown corundum sand, which has moderate hardness, sharp edges, and is conducive to forming a uniform, blunt round shape.

[0071] Parameter optimization experiment (orthogonal experiment): Design of L9(3³) orthogonal experiment. Factors: A (blasting pressure: 0.2, 0.25, 0.3 MPa), B (blasting time: 20, 30, 40 s), C (blasting angle: 30°, 45°, 60°). Evaluation indicators: blunt radius rε, edge micromorphology (SEM observation to see if new defects are introduced), and subsequent coating adhesion test (scratch method critical load Lc).

[0072] Experimental Results and Implementation: Range analysis showed that blasting pressure had the most significant impact on the blunt radius, followed by blasting time, while blasting angle mainly affected uniformity. The optimal combination was A2B2C2 (pressure 0.25 MPa, time 30 s, angle 45°). Under these parameters, the average blunt radius rε was approximately 25 μm, and SEM showed a smooth cutting edge transition, with TiC particles not being "crushed" or peeled off.

[0073] S4. Post-processing and verification: Cleaning: Use compressed air and alcohol to clean the blades and thoroughly remove any sand residue.

[0074] Quality Inspection: Morphology and dimensions: The straightness, angle and blunt radius of the cutting edge were checked with a tool microscope.

[0075] Microscopic analysis: SEM / EDS inspection of the cutting edge after sandblasting confirmed that the coating was intact and the interface was undamaged.

[0076] Adhesion test: The coating surface near the passivated cutting edge was tested using a scratch tester, and the critical load Lc2 (coating completely peeled off) value of the coating was measured to be above 55N.

[0077] Ultimate verification of cutting performance: Anti-scraping test: conducted on a CNC lathe. Workpiece: 45# steel round bar with 4 evenly distributed radial grooves (e.g., Figure 10a (As shown). Cutting parameters: Vc=250m / min, ap=2.0mm, f=0.25mm / rev. After 2300 impacts, the machine was stopped for inspection. The results were satisfactory: the cutting edge of the insert showed no visible macroscopic chipping or defects (such as...). Figure 10b (As shown). This demonstrates that the uniform cutting edge formed by controlled sandblasting passivation greatly improves impact resistance.

[0078] Wear resistance test: under continuous turning without interruption (e.g.) Figure 10c As shown in the figure, the cutting parameters are the same as those in the anti-breakage test. Figure 10d As shown, after 42 minutes of continuous cutting, the width of the wear band on the flank face, VB, reached 0.21 mm, demonstrating good durability.

[0079] Example 3: Adaptive Adjustment Process Parameters for Special Gradient Materials This embodiment illustrates how, when faced with a novel or more complex gradient composite material tool, systematic process development and parameter determination can be carried out based on the core ideas of the present invention.

[0080] Input: A novel gradient tool blank (e.g., a WC-particle-reinforced cobalt-based superalloy gradient-coated drill bit).

[0081] Output: A set of validated, optimized grinding and passivation process parameters for this material.

[0082] S1. Material property analysis and initial parameter preset: By using material certificates, SEM / EDS, XRD, hardness gradient testing, and other methods, we can understand the composition distribution, phase composition, hardness and fracture toughness of the gradient material.

[0083] Based on material properties and experience with similar materials, preset the initial grinding parameter range (such as grinding wheel type and speed range) and passivation process (select laser or sandblasting).

[0084] S2. Iterative Optimization Process (Step-by-Step Closed Loop): S2.1 First Stage Grinding Parameter Exploration: Small-scale grinding tests were conducted within a preset range using single-factor or Taguchi methods.

[0085] Testing: Immediately perform surface roughness, subsurface damage, microhardness testing, and rough assessment of residual stress on the ground sample.

[0086] Analysis: Identify the key parameters that lead to poor surface quality, subsurface cracks, or thermal damage to the material. Adjust the parameters and proceed to the next round of testing.

[0087] Objective: To obtain 1-2 sets of parameter combinations that show "no visible serious damage".

[0088] S2.2 Second-stage passivation process matching and optimization: Using the best grinding samples obtained in the first stage, passivation process tests (laser or sandblasting) were conducted.

[0089] Design orthogonal experiments to optimize passivation parameters.

[0090] Inspection: Measure the radius and uniformity of the blunt circle, the change in surface roughness, and observe for new defects under SEM.

[0091] Analysis: Determine the combination of passivation parameters that can achieve the target blunt circle radius without introducing new damage.

[0092] S2.3 Phase 3 Integration Verification and Fine-tuning: The optimal grinding and passivation parameters obtained in the first two stages are combined to process the complete tool.

[0093] Comprehensive testing: Conduct a full set of quality tests (morphology, microstructure, roughness, bonding strength, etc.).

[0094] Pre-cutting test: Conduct short-duration or moderate-condition cutting tests to quickly verify performance.

[0095] Feedback and fine-tuning: If unexpected wear or breakage occurs during the cutting test, return to analyze the specific failure mode and adjust the grinding or passivation parameters accordingly. This process may require 1-2 iterations.

[0096] S2.4 Final Performance Calibration in Phase Four: Several tool samples were prepared using a finely tuned and stabilized process.

[0097] Conduct complete chipping resistance and wear life tests according to standard or customer-required testing specifications to obtain reliable performance data.

[0098] It should be noted that the above embodiments are exemplary applications based on the above technical principles, and the specific parameters can be adjusted according to the actual tool material and structure.

[0099] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for suppressing grinding damage and controlling wear of gradient composite material cutting tools, characterized in that, Includes the following steps: S1. Provide an ultrahard coated tool blank with a gradient structure, wherein the gradient structure is formed by laser additive manufacturing technology; S2. The tool blank is subjected to profile grinding using a slow feed grinding strategy, and the grinding parameter combination suitable for gradient material properties is determined through process experiments. The parameter combination includes at least grinding speed, workpiece feed speed and grinding depth. S3. Perform precision passivation treatment on the grinding tool edge, wherein the passivation treatment is laser passivation polishing and / or controlled sandblasting passivation, in order to eliminate micro-defects on the edge and form a target blunt circle radius; S4. Clean, inspect, and verify the cutting performance of the passivated cutting tool.

2. The method according to claim 1, characterized in that, In step S1, the gradient structure is a composite material structure in which the composition and properties change continuously or abruptly along the thickness or a specific direction, including: Ceramic-ceramic gradient materials: The matrix is ​​Al2O3, ZrO2 or their eutectic ceramics, and the reinforcing phase is TiC, SiC, WC or diamond particles, and the content of the reinforcing phase varies in a gradient along a specified direction; Metal-ceramic gradient materials: The metal matrix is ​​an iron-based, nickel-based, or cobalt-based alloy, and the ceramic reinforcing phase is TiC or WC carbide, with the ceramic phase content varying in a gradient along the coating thickness direction.

3. The method according to claim 1, characterized in that, In step S2, the creeping feed grinding strategy specifically refers to: The linear velocity of the grinding wheel ranges from 20 to 60 m / s; The axial feed rate of the workpiece is 8.33 × 10⁻⁶. -4 m / s to 1.58×10 - ³m / s; The grinding depth is adjusted according to the processing stage, with rough grinding depth of 4-10μm and fine grinding depth of 1-4μm.

4. The method according to claim 3, characterized in that, In step S2, the grinding wheel grit size is selected according to the grinding stage: For rough machining or deep grinding of gradient ceramic materials, diamond grinding wheels with a grit size of D64-D100 should be selected. When finishing or grinding the final profile of a tool, use a diamond grinding wheel with a grit size of D46 or finer.

5. The method according to claim 1, characterized in that, In step S2, the grinding parameter combination is obtained through orthogonal experiments designed for specific gradient materials. The factor levels of the orthogonal experiments include grinding wheel linear speed, workpiece feed speed, grinding depth and grinding wheel grit size. The optimization objectives are to minimize grinding force, minimize surface roughness and eliminate visible grinding burns.

6. The method according to claim 1 or 5, characterized in that, Step S2 also includes an active suppression step for grinding thermal damage: by increasing the grinding wheel linear speed, applying high-efficiency coolant, and optimizing the coolant spray angle and flow rate, the peak temperature of the grinding zone is controlled within the range that the interface between the gradient material coating and the substrate can withstand, so as to avoid the decrease or detachment of coating adhesion caused by grinding burn.

7. The method according to claim 1, characterized in that, In step S3, the laser passivation polishing adopts a dual laser beam system, including an infrared continuous laser for material preheating or softening and an ultraviolet short pulse or ultrashort pulse laser for precision material removal. The polishing parameters were optimized through experiments, including: laser wavelength, power, pulse frequency, scanning speed, scanning path, and spot overlap rate.

8. The method according to claim 1, characterized in that, In step S3, the controllable sandblasting passivation uses a sandblasting device with adjustable air pressure, and the abrasive is diamond, alumina or silicon carbide with a particle size of 100-800 mesh; the sandblasting time is controlled at 10-60 seconds according to the target blunt circle radius; the sandblasting angle is an acute angle relative to the tangent direction of the cutting edge to avoid vertical impact.

9. The method according to claim 1, 7 or 8, characterized in that, In step S3, before passivation, the passivation process parameters are optimized by orthogonal experiment or response surface methodology to obtain a stable and design-compliant cutting edge blunt radius. Optimization factors include passivation time and equipment motion parameters. The target blunt radius is determined according to the tool type and coating thickness as follows: light-duty blunt radius 10-30μm, medium-duty blunt radius 30-80μm, and heavy-duty blunt radius 80-150μm.

10. The method according to claim 1, characterized in that, In step S4, the cutting performance verification includes: Anti-chipping test: Under the conditions of cutting speed Vc=250m / min, depth of cut ap=1.0mm, and feed rate f=0.2mm / rev, the grooved 45# steel bar is subjected to intermittent turning. It is required that the cutting edge has no macroscopic chipping after ≥1300 impact cycles. Wear resistance test: Under the same cutting parameters, 35CrMo alloy structural steel is continuously turned, and the cutting time is required to reach ≥40 minutes when the wear on the flank face reaches 0.2mm.

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