A nano-minimum lubrication cutting method and tool processing technology

Abstract

The present invention provides a nano-minimum lubrication cutting method and a processing technology for a tool, comprising the following steps: performing cutting processing with a tool having a concave-convex composite textured soft-hard combination coating, wherein the tool-chip contact area surface of the tool is provided with a lubricating soft coating, and the surface of the soft coating has a concave-convex composite texture morphology; during the tool cutting process, spraying a cutting fluid droplet containing nanoparticles onto the tool-chip contact area between the workpiece and the tool, and the nanoparticles flow into the concave-convex composite texture morphology of the tool-chip contact area along with the cutting fluid. The cutting fluid containing nanoparticles is sprayed from the flank direction to allow the nanoparticles to reach the boundary of the tool-chip contact area. In the cutting method of the present invention under the condition of minimum lubrication with the addition of tungsten disulfide nanoparticles, the tool can simultaneously have good coating adhesion, good friction and wear performance, and uniform lubrication performance, thereby improving the service life of the tool and the processing quality.

Description

Technical Field

[0001] The present invention relates to the field of tool processing, and in particular to a nanometer micro-lubrication cutting method and a tool processing technology. Background Art

[0002] Carbide cutting tools, currently the mainstream, are generally not processed with cutting fluid. This is because carbide is particularly sensitive to temperature. Insufficient or uneven cutting fluid flow during cutting can cause uneven heating and cooling of the carbide tool, leading to cracks and tool failure. However, when machining hard, strong, and thermally conductive workpieces (difficult-to-machine materials), such as titanium alloys, the high temperature in the tool-chip region can cause adhesion and diffusion between the carbide insert and certain elements in the workpiece, leading to rapid tool wear. Therefore, achieving uniform lubrication and tool wear during carbide machining has become a challenge.

[0003] Applying a hard coating such as nitride (TiN, CrN, AlCrN) on the surface of cemented carbide to increase the wear resistance and hardness of the tool surface for dry cutting is an option for dealing with difficult-to-machine materials. However, there are problems with high friction and friction coefficient during the friction process. The resulting temperature rise makes the diffusion phenomenon more serious, resulting in tool sticking problems.

[0004] The prior art discloses the preparation of a Ti / TiN transition layer and an alternating deposition of a TiCN hard coating and a MoS2 / C soft coating on the front face of a tool. This composite coating can bring out the respective properties of the soft and hard coatings, but due to the properties of the MoS2 / C soft coating, it is not suitable for wet working conditions, and the soft coating is easily worn during processing. The prior art discloses a tool in which a composite of pits and grooves is prepared in the tool-chip contact area and combined with a hard coating, which reduces the tool-chip contact length, reduces the cutting force and the cutting temperature. However, this patent requires the use of a large amount of cutting fluid to be effective, which will pollute the environment. The prior art discloses the preparation of a number of grooves with gradient depth on the back face of the tool, which enables the tool to store grinding chips and quickly cool them, greatly improving the heat dissipation capacity of the coating, thereby increasing the dry cutting life of the tool. Although the wear state can be improved, the chip flow mode is not improved. As the processing continues, the pit surface is prone to clogging and failure, resulting in the generation of a large amount of cutting heat.

[0005] Existing technology uses soft coatings on cutting tools. These coatings are made by applying a lamellar, low-shear-strength material to the surface of the substrate. However, these coatings are relatively low in hardness and have poor sustained lubrication properties, resulting in rapid wear during cutting. Traditional lubrication techniques also require large amounts of cutting fluid, which has difficulty penetrating the tool-chip area, resulting in significant waste and uneven cooling, which can lead to blade cracks. This necessitates new lubrication technologies. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a nano-micro-lubrication cutting method and a tool processing technology, which can solve the problems of uneven lubrication and tool wear during the processing of cemented carbide tools. The cutting method of the tool with a concave-convex composite texture soft-hard combination coating under micro-lubrication with the addition of tungsten disulfide (WS2) nanoparticles can simultaneously have good coating adhesion, good friction and wear performance and uniform lubrication performance, thereby improving the service life of the tool and the processing quality. In addition, a small amount of lubricating cutting fluid is used in this method, which can avoid excessive pollution of the environment by the cutting fluid.

[0007] The present invention achieves the above technical objectives through the following technical means.

[0008] A nano-minimum lubrication cutting method comprises the following steps:

[0009] Cutting is performed using a tool with a concave-convex composite textured soft-hard combination coating, wherein the tool-chip contact area surface of the tool is provided with a lubricating soft coating, and the surface of the soft coating has a concave-convex composite texture morphology;

[0010] During the tool cutting process, cutting fluid droplets containing nanoparticles are sprayed onto the tool-chip contact area between the workpiece and the tool, and the nanoparticles flow into the concave-convex composite texture morphology of the tool-chip contact area along with the cutting fluid.

[0011] Furthermore, the cutting fluid containing nanoparticles is sprayed from the flank surface so as to allow the nanoparticles to reach the boundary of the tool-chip contact area.

[0012] Furthermore, the cutting fluid is a vegetable oil with a kinematic viscosity greater than 2000, the nanoparticles in the cutting fluid are WS2 particles, the particle size of the nanoparticles is 80-100 nm, and the cutting fluid is sprayed through a spray lubrication system.

[0013] Furthermore, a tool-chip contact area of ​​the tool is provided with a concave-convex composite texture morphology, and a hard coating and a soft coating are coated on the surface of the concave-convex composite texture morphology.

[0014] Furthermore, the concave-convex composite texture morphology is composed of a number of evenly distributed concave-convex composite texture units, and the concave-convex composite texture unit includes a pit and a protrusion, the pit is located at the center of the concave-convex composite texture unit, and the pit is surrounded by protrusions.

[0015] Furthermore, the diameter of the pit is 60-80 μm, the depth of the pit is 8 μm; the diameter of the protrusion is 80-100 μm, the height of the protrusion is 15-20 μm, the spacing a1 of the concave-convex composite texture units is 300-400 μm, and the area occupancy of the concave-convex composite texture morphology is S1 = 20%-30%.

[0016] Furthermore, the thickness of the soft coating layer is t2 = 10 μm; the thickness of the hard coating layer is t1 = 5 μm; the material of the soft coating layer is WS2; and the material of the hard coating layer is diamond-like carbon.

[0017] A processing technology for a cutting tool used in a nano-minimum lubrication cutting method comprises the following steps:

[0018] Pre-treat the tool-chip contact area of ​​the tool to make the surface roughness Ra of the tool-chip contact area less than 0.05

[0019] The concave-convex composite texture morphology is processed in the tool-chip contact area by laser;

[0020] Depositing soft and hard coating materials on the concave-convex composite texture.

[0021] Furthermore, the hard coating is deposited using a physical vapor deposition process; the soft coating is deposited using an electrofluid jet process;

[0022] Furthermore, the parameters of the laser processing are: laser power of 150W, laser pulse frequency of 2000KHz, and laser defocusing amount of 0mm.

[0023] The beneficial effects of the present invention are:

[0024] 1. The nano-minimum-quantity-lubrication cutting method described in this invention utilizes a tool with a composite textured soft-hard coating and WS2 nanoparticles for minimum-quantity lubrication. The nano-lubricant flowing from the flank surface reaches the contact areas between the tool and the chip, and between the tool and the workpiece, where it is rapidly absorbed and forms an effective lubricating film.

[0025] 2. The nano-minimum quantity lubrication cutting method described in this invention features a composite concave-convex texture in the tool-chip contact area, coated with a soft and hard coating. The hard coating enhances the hardness and wear resistance of the raised areas, separating the chips from the tool rake face and protecting the tool surface. The soft coating continuously forms a lubricating film on the tool surface, reducing friction. As the surface coating wears away, the coating material stored in the recesses is dissipated, forming a lubricating film that reduces friction and enhances lubrication performance. During the actual nanoparticle minimum quantity lubrication process, cutting fluid containing WS2 particles is atomized through a nozzle into the tool-chip contact area, replenishing the surface and recesses, maintaining the tool surface, improving workpiece machining quality, and extending tool life.

[0026] 3. In the nano-minimum-quantity lubrication cutting method described in this invention, a soft coating is applied to the cutting tool over a hard coating. The soft coating is a lamellar, low-shear-strength material applied to the substrate surface. Because the layers are primarily held together by weak van der Waals forces, they exhibit strong sliding properties. During the cutting process, the soft coating on the tool surface is evenly transferred to the surface of the chip material, forming a transfer film. This shifts friction at the tool-chip interface to friction between the transfer film and the soft coating, as well as within the soft coating itself. This reduces tool-chip shear and friction, slows tool surface adhesion, and improves tool wear resistance and service life. Unlike the anti-wear properties of hard coatings, soft coatings primarily function to reduce friction and lubricate, thereby lowering the coefficient of friction.

[0027] 4. The nano-minimum-quantity-lubrication cutting method described in this invention combines the advantages of surface microtexture and surface coatings. The concave-convex cavities of the surface microtexture and the tiny pores created by laser melting increase the specific surface area, allowing the coating material to adhere more easily. Furthermore, the laser-treated tool surface contains more chemical elements compatible with the coating material, improving surface compatibility. After applying a hard coating to the tool surface, a soft coating is applied. The soft coating's low friction coefficient and film-forming stability compensate for the temperature rise caused by the high friction during machining. The hard coating also provides support for the soft coating during cutting, protecting the substrate. The addition of nano-minimum-quantity-lubrication technology allows the nanoparticles to act as rolling bearings between the friction pair surfaces. Furthermore, the nanoparticles can be deposited on the worn areas of the soft coating, compensating for material loss and, to a certain extent, addressing the issue of soft coating material loss, further maintaining surface lubrication.

[0028] 5. The tool processing process described in the present invention applies a laser to the substrate, causing the substrate material to rapidly heat up and vaporize, removing excess surface material while eliminating thermal stress. This reduces grain size and increases material hardness, resulting in various surface morphologies. The concave-convex composite texture obtained by this technology can reasonably reduce the tool-chip contact length, improve chip flow, and reduce cutting forces and temperatures. During the cutting process, the reduction in local contact area caused by the microstructure reduces friction. Under relative sliding, wear debris can cause a plowing effect on the material, leading to adhesion. The presence of the concave-convex morphology can capture tiny debris, prevent debris from accumulating on the rake face, and reduce adhesion. At the same time, its concave structure can store lubricant and maintain surface wettability, while the protrusions separate the chips from the tool rake face, protecting the integrity of the tool face and extending tool life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 A three-dimensional diagram of the tool according to the present invention.

[0031] Figure 2 This is a cross-sectional view of the concave-convex composite texture morphology described in the present invention.

[0032] Figure 3 This is a top view of the concave-convex composite texture morphology described in the present invention.

[0033] Figure 4 This is a schematic diagram of the actual cutting of the tool described in the present invention under the minimal lubrication of WS2 particles.

[0034] Figure 5 The figure is a flow chart of the tool processing process according to the present invention.

[0035] Figure 6 This is a flow chart of the nano-minimum lubrication cutting method described in the present invention.

[0036] In the picture:

[0037] 1-Tool-chip contact area; 2-Concave-convex composite texture morphology; 3-Pits; 4-Bumps; 5-Hard coating; 6-Soft coating; 7-Spray lubrication system; 8-Cutting fluid; 9-Nanoparticles. DETAILED DESCRIPTION

[0038] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0040] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0041] like Figure 4 and Figure 6 As shown, the nano-minimum lubrication cutting method of the present invention comprises the following steps:

[0042] Cutting is performed using a tool with a concave-convex composite textured soft-hard combination coating, wherein a surface of a tool-chip contact area 1 of the tool is provided with a lubricating soft coating 6, and the surface of the soft coating 6 has a concave-convex composite texture morphology 2;

[0043] During the tool cutting process, a cutting fluid 9 containing nanoparticles is sprayed as droplets to the tool-chip contact area 1 between the workpiece and the tool, and the nanoparticles 9 flow into the concave-convex composite texture morphology 2 of the tool-chip contact area 1 along with the cutting fluid. The cutting fluid 9 containing nanoparticles is sprayed in the direction of the back face of the tool, so as to enable the nanoparticles 9 to reach the boundary of the tool-chip contact area 1. The cutting fluid 8 is a vegetable oil with a kinematic viscosity greater than 2000, and the nanoparticles in the cutting fluid 8 are molybdenum disulfide WS2 particles with a particle size of 80~100nm. The cutting fluid 8 is sprayed through a spray lubrication system 7. During the tool cutting process of the present invention, a trace / small amount of cutting fluid 8 is used, which is sprayed in the form of droplets to achieve a lubricating effect, thereby reducing the amount of cutting fluid used excessively in traditional cutting processes. The flow rate sprayed by the spray lubrication system does not exceed 0.45 g / min.

[0044] like Figure 1 、 Figure 2 and Figure 3 As shown, a concave-convex composite texture morphology 2 is provided in the tool-chip contact area 1 of the tool, and a hard coating 5 and a soft coating 6 are coated on the surface of the concave-convex composite texture morphology, and the soft coating 6 is located on the surface of the hard coating 5. The concave-convex composite texture morphology 2 is composed of a number of evenly distributed concave-convex composite texture units, and the distribution direction of the concave-convex composite texture is parallel to the main cutting edge of the tool. The concave-convex composite texture unit includes a pit 3 and a protrusion 4. The pit 3 is located at the center of the concave-convex composite texture unit, and the pit 3 is surrounded by protrusions 4. The nanoparticles 9 can be located in the pit 3. The pit 3 can store nanoparticles 9, and the coating material can be replenished when the surface soft and hard coating materials are exhausted, thereby extending the adhesion time of the surface coating material; the protrusion 4 separates the chips from the tool surface matrix, protects the tool surface, and extends the service life of the tool. This concave-convex composite texture can effectively improve the contact state between the tool and the chip.

[0045] like Figure 2 As shown, the diameter d1 of the pits 3 is 60-80 μm, and the depth h1 of the pits 3 is 8 μm. The diameter d2 of the protrusions 4 is 80-100 μm, and the height h2 of the protrusions 4 is 15-20 μm. The spacing a1 between the concave-convex composite texture units is 300-400 μm, and the area occupancy S1 of the concave-convex composite texture morphology 2 is 20%-30%. The soft coating 6 has a thickness t2 of 10 μm, and the hard coating 5 has a thickness t1 of 5 μm. The tool surface is first coated with a DLC hard coating 5 using PVD technology, and then a WS2 soft coating 6 is deposited using electrofluid jet technology. The soft coating 6 is made of WS2, and the hard coating 5 is made of diamond-like carbon (DLC).

[0046] like Figure 5 As shown, the processing technology of the tool used in the nano-minimum lubrication cutting method of the present invention includes the following steps:

[0047] The tool-chip contact area 1 of the tool is pretreated: first, the burrs in the tool-chip contact area 1 are smoothed with sandpaper, and the surface is polished into a mirror surface with a roughness Ra less than 0.05 using a polishing cloth, and then cleaned in an ultrasonic cleaner with 99% high-concentration anhydrous ethanol and allowed to dry naturally.

[0048] Laser processing of concave-convex composite texture morphology: The parameters of the laser processing of the composite texture morphology are: the laser is an RFLC500 laser machine, the laser power is 150-250w, the laser pulse frequency is 2000-4000KHz, and the laser defocus amount is 0mm.

[0049] The coating material is deposited on the surface of the concave-convex composite texture. The hard coating is deposited by physical vapor deposition process; the soft coating is deposited by electrofluid jet process.

[0050] Example

[0051] In this embodiment, the tool is a YG3 carbide tool, the hard coating 5 is a diamond-like coating DLC, the soft coating 6 is a tungsten disulfide WS2 coating, the coating method is electrofluid injection technology, and the nanoparticles are WS2 particles with a particle size of 80 nm.

[0052] The specific steps are as follows:

[0053] Use sandpaper to smooth the burrs on the front cutting edge of the tool, and use a polishing cloth to polish the surface to a mirror surface with a roughness of Ra of 0.02. Use 99% high-concentration anhydrous ethanol in an ultrasonic cleaner to clean it, and finally let it dry naturally;

[0054] Machining the concave-convex composite texture morphology in the tool-chip contact area 1 of the tool: After polishing and cleaning the tool surface, the tool rake face was textured using an RFL C500 laser machine with a power of 150W, a pulse frequency of 2000KHz, a defocus of 0mm, and one processing pass. To avoid damage to the cutting edge due to the texture, the distance between the laser spot and the main cutting edge was adjusted to 150-200μm. The machined concave-convex composite texture was parallel to the main cutting edge to obtain a better cutting effect.

[0055] Processing concave-convex composite texture 2, where the diameter of pit 3 is d1 = 60μm, the depth of pit 3 is h1 = 8μm, and the main function of pit 3 is to store coating material, replenish coating material for subsequent processing, and maintain the wettability of the tool surface. The diameter of protrusion 4 is d2 = 80μm, the height of protrusion 4 is h2 = 20μm, and the main function of protrusion 4 is to support chips, keep chips away from the tool rake face, and improve tool life. The spacing between the concave-convex composite textures is a1 = 300 microns, the distance from the main cutting edge is a2 = 120μm, and the composite texture area occupancy rate is S1 = 22%; the error of all the above morphological parameters is about 6μm;

[0056] Coating Treatment: To increase the wear resistance and hardness of the tool surface, a DLC hard coating is applied to the textured surface using magnetron sputtering, a method known as physical vapor deposition (PVD). This method achieves high speed, low temperature, and minimal damage. 5 To enhance the wettability of the tool surface, a WS2 soft coating is deposited on the tool surface using electrohydrodynamic jet deposition. 6 The texturing increases the specific surface area of ​​the hard coating, while the hard coating provides support for the soft coating, which in turn reduces the surface friction coefficient of the hard coating. The result is a tool with a composite hard and soft coating.

[0057] During the actual cutting process, the fluid supply direction of the spray lubrication system 7 affects the uniform formation of the oil film at the tool-chip interface during the processing. In this embodiment, the cutting fluid 8 is supplied from the back face direction. For the back face direction, the workpiece has a smooth machined surface, and due to the existence of the back angle, the cutting fluid 8 can more easily reach the boundary of the tool-workpiece contact area. The WS2 nanoparticles 9 flow into the tool-chip contact interface with the cutting fluid, thereby enhancing the strength of the lubricating film.

[0058] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0059] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A nano-minimum lubrication cutting method, characterized in that: The following steps are included: Cutting is performed using a tool with a concave-convex composite textured soft-hard combined coating, wherein a tool-chip contact area (1) of the tool is provided with a lubricating soft coating (6), and the surface of the soft coating (6) has a concave-convex composite textured morphology (2); During the tool cutting process, a cutting fluid (8) containing nanoparticles is sprayed onto the tool-chip contact area (1) between the workpiece and the tool, and the nanoparticles (9) flow into the concave-convex composite texture morphology (2) of the tool-chip contact area (1) along with the cutting fluid; in: The cutting fluid (8) containing nanoparticles is sprayed from the back face of the cutting tool, so that the nanoparticles (9) reach the boundary of the tool-chip contact area (1); the cutting fluid (8) is a vegetable oil with a kinematic viscosity greater than 2000, the nanoparticles in the cutting fluid (8) are WS2 particles, and the particle size of the nanoparticles is 80-100 nm. The cutting fluid (8) is sprayed through a spray lubrication system; The tool-chip contact area (1) of the tool is provided with a concave-convex composite texture morphology (2), and the surface of the concave-convex composite texture morphology is coated with a hard coating (5) and a soft coating (6); the concave-convex composite texture morphology (2) is composed of a plurality of evenly distributed concave-convex composite texture units, and the concave-convex composite texture unit includes a pit (3) and a protrusion (4), the pit (3) is located at the center of the concave-convex composite texture unit, and the pit (3) is surrounded by protrusions (4), and the nanoparticles (9) can be located in the pit (3); the diameter of the pit (3) is 60-80 μm, and the depth of the pit (3) is 8 μm; the diameter of the protrusion (4) is 80-100 μm, and the height of the protrusion (4) is 15-20 μm, the spacing a1 of the concave-convex composite texture unit is 300-400 μm, and the area occupancy rate of the concave-convex composite texture morphology (2) is S1 = 20%-30%; The soft coating (6) has a thickness of t2 = 10 μm; the hard coating (5) has a thickness of t1 = 5 μm; the soft coating (6) is made of WS2; and the hard coating (5) is made of diamond-like carbon.

2. A process for processing a cutting tool used in the nano-minimum lubrication cutting method according to claim 1, characterized in that: The steps include: Pre-treating the tool-chip contact area (1) of the tool so that the surface roughness Ra of the tool-chip contact area (1) is less than 0.05; Processing a concave-convex composite texture morphology (2) in the tool-chip contact area (1) by laser processing; Depositing soft and hard coating materials on the concave-convex composite texture.

3. The processing technology according to claim 2, characterized in that: The hard coating is deposited using a physical vapor deposition process; the soft coating is deposited using an electrofluid jet process.

4. The processing technology according to claim 2, characterized in that: The parameters of the laser processing are: laser power of 150W, laser pulse frequency of 2000KHz, and laser defocus of 0mm.

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