BIONIC AUSTRALIAN THORNY DEVIL GRINDING WHEEL, GRINDING DEVICE, AND PREPARATION PROCESS

Abstract

The present disclosure provides a bionic Australian thorny devil grinding wheel, a grinding device, and a preparation process, and relates to the field of grinding equipment. For the problem of the poor effect of conveying grinding fluid by a grinding wheel at present, imitating semi-open capillary channels and a honeycomb structure on the skin of the Australian thorny devil, prisms with isosceles trapezoidal bottom surfaces are arranged on a matrix in sequence to form directional liquid self-conveying flow channels and a superhydrophilic honeycomb-like hexagonal distribution structure.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serial no. 202311752510.X, filed on Dec. 19, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The present disclosure relates to the field of grinding equipment, and in particular to, a bionic Australian thorny devil grinding wheel, a grinding device, and a preparation process.

Description of Related Art

Grinding is an essential precision machining method for achieving high surface quality and dimensional accuracy, playing a crucial role in manufacturing fields such as aviation and aerospace. However, under the impact of an air barrier layer generated during high-speed rotation of a grinding wheel, it is challenging for grinding fluid to effectively enter a grinding wedge zone, leading to reduced service life of the grinding wheel and workpiece quality.

Existing solutions involve increasing the supply of the grinding fluid, changing the shape of a grinding fluid nozzle, and changing the composition of the grinding fluid to achieve the functions of improving cooling, lubrication, and chip removal. However, these methods are low in grinding fluid utilization rate, and are difficult in efficient machining.

Through researches, the Chinese patent (Application No. 201911124302.9) discloses a structured grinding wheel based on a bionic idea, which includes an abrasive grain section and bionic structure grooves. The bionic structure grooves disposed in a surface of the grinding wheel are arc-shaped and are manufactured through laser processing to enhance the effects of cooling, lubrication and chip removal in the grinding process, effectively restraining grinding burns. The Chinese patent (Application No. 202111532987.8) discloses a bionic grinding wheel based on body scales of grass carp and phyllotaxis arrangement. Learning from the body scales of grass carp, the bionic structure grooves have arrangement forms with the characteristics of inhibiting flow field disturbance, having a high average convective heat transfer coefficient, and being resistant to adhesion. The bionic grinding wheel disrupts an air barrier generated during the high-speed rotation of the grinding wheel, such that when the grinding wheel performs grinding machining, the grinding fluid utilization rate is high, and the heat dissipation performance is good, thereby prolonging the service life of the grinding wheel and improving the machining quality of workpieces. However, the self-conveying effect of a grinding wheel matrix on a cooling medium is neglected, causing that the overall conveying effect of the grinding wheel on the grinding fluid is difficult to meet the demand.

SUMMARY

An objective of the present disclosure is to provide a bionic Australian thorny devil grinding wheel, a grinding device, and a preparation process for defects in the prior art. Mimicking semi-open capillary channels and a honeycomb structure on skin of Australian thorny devil, prisms with isosceles trapezoidal bottom surfaces are arranged on a matrix in sequence to form directional liquid self-conveying flow channels and a superhydrophilic honeycomb-like hexagonal distribution structure, thereby improving the infiltration conveying effect of a lubricant in a grinding zone, increasing the grinding fluid utilization rate, and reducing grinding force and grinding temperature.

A first objective of the present disclosure is to provide a bionic Australian thorny devil grinding wheel, adopting the following solution:

• • including:
  • a matrix, having a superhydrophobic layer arranged on an outer peripheral surface; and
  • abrasive grains which are prismatic with an isosceles trapezoidal bottom surface, where an axis of the abrasive grain is distributed in a radial direction of the matrix, one end of the abrasive grain in an axial direction is connected to the outer peripheral surface of the matrix, and the other end is of a hydrophilic structure; and two adjacent abrasive grains are arranged at intervals to form a hexagonal-prism-shaped abrasive grain cluster, and gaps are reserved between adjacent abrasive grain clusters, such that a hexagonal surrounding flow channel is formed in a circumferential direction of each abrasive grain cluster.

Further, the outer peripheral surface of the matrix is covered with the abrasive grain clusters arranged in array, and the abrasive grain clusters are arranged in a honeycomb-like hexagon.

Further, along a circular direction of the outer peripheral surface of the matrix, the abrasive grain clusters are arranged at intervals into a plurality of columns, and the adjacent columns of abrasive grain clusters are staggered.

Further, a middle flow channel is formed between two abrasive grains of the abrasive grain cluster, and the middle flow channel is located between side surfaces of corresponding isosceles trapezoid bottom edges of the two abrasive grains.

Further, the middle flow channel is tangentially distributed along the position of the outer peripheral surface of the matrix, and communicates with the surrounding flow channel.

Further, both the middle flow channel and the surrounding flow channel are semi-open capillary channels to exert capillary action with a tendency toward the hydrophilic structure to water inside the middle flow channel and the surrounding flow channel.

Further, the abrasive grains are chamfered corresponding to side ridges of prisms.

A second objective of the present disclosure is to provide a grinding device, utilizing the bionic Australian thorny devil grinding wheel of the first objective.

A third objective of the present disclosure is to provide a process for preparing a bionic Australian thorny devil grinding wheel, including:

• • performing superhydrophobic treatment on an outer peripheral surface of a matrix to obtain a superhydrophobic layer;
  • processing abrasive grains, such that a hydrophilic structure is formed at one end of the abrasive grain; and
  • pairing the abrasive grains to obtain abrasive grain clusters, adhering the abrasive grains to the outer peripheral surface of the matrix in a manner of the abrasive grain clusters, arranging the adjacent abrasive grain clusters at intervals, and forming a bionic Australian thorny devil flow channel between the adjacent abrasive grains, where the abrasive grain clusters are arranged in a bionic honeycomb structure.

Further, a masking method is adopted to adhere the abrasive grains to the matrix.

Compared with the prior art, the present disclosure has the following advantages and positive effects:

• • (1) For the problem of the poor effect of conveying grinding fluid by a grinding wheel at present, mimicking the semi-open capillary channels and the honeycomb structure on skin of the Australian thorny devil, and prisms with isosceles trapezoidal bottom surfaces are arranged on the matrix in sequence so as to form the directional liquid self-conveying flow channels and the superhydrophilic honeycomb-like hexagonal distribution structure, thereby improving the infiltration conveying effect of the lubricant in the grinding zone, increasing the grinding fluid utilization rate, and reducing grinding force and grinding temperature.
  • (2) The superhydrophobic matrix surface of the grinding wheel has good self-conveying capacity, which can make the grinding fluid flow to the grinding zone at the tail end of the hydrophilic abrasive grain cluster from the superhydrophobic matrix surface, and droplets are adsorbed after making contact with the hydrophilic abrasive grain cluster, thereby increasing cooling and lubricating efficiency of the grinding fluid.
  • (3) The abrasive grain clusters are arranged in a hydrophilic bionic honeycomb hexagon, and due to the hexagonal structure, the surface of the grinding wheel has super hydrophilicity, thereby making water stay on the surface of the grinding wheel without volatilization and keeping the physical stability of a liquid film.
  • (4) The bionic grinding wheel and ultrasonic vibration assisted grinding are combined, and due to the self-conveying function of the bionic grinding wheel, by utilizing the properties of ultrasonic vibration in infiltrating and enhancing a heat transfer coefficient of the grinding fluid, the cooling and lubricating effect of the grinding fluid is improved, and the grinding temperature is effectively reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and descriptions thereof are used to explain the present disclosure, and do not constitute an improper limitation of the present disclosure.

FIG. 1 is a schematic diagram of a bionic Australian thorny devil grinding wheel according to Embodiment 1, Embodiment 2, and Embodiment 3 of the present disclosure.

FIG. 2 is a schematic diagram of a grinding device according to Embodiment 1 and Embodiment 2 of the present disclosure.

FIG. 3 is a force analysis diagram of grinding fluid self-conveying of the bionic Australian thorny devil grinding wheel according to Embodiment 1, Embodiment 2, and Embodiment 3 of the present disclosure.

FIG. 4 is a flowchart of a process for preparing the bionic Australian thorny devil grinding wheel according to Embodiment 3 of the present disclosure.

FIG. 5 is a schematic diagram of spray-assisted laser processing according to Embodiment 3 of the present disclosure.

FIG. 6 is a schematic diagram of distribution of abrasive grain clusters on the bionic Australian thorny devil grinding wheel according to Embodiment 1, Embodiment 2, and Embodiment 3 of the present disclosure.

1—bionic Australian thorny devil grinding wheel, 2—matrix, 3—abrasive grain cluster, 4—grinding wheel guard, 5—minimum quantity lubrication nozzle, 6—grinding fluid conveying pipeline, 7—compressed air conveying pipeline, 8—ultrasonic vibrator, 9—laser device, 10—laser beam, 11—beam expander, 12—reflector, 13—aperture, 14—Glan prism, 15—focus lens, and 16—movable machining platform.

DESCRIPTION OF THE EMBODIMENTS

Embodiment 1

In a typical embodiment of the present disclosure, as shown in FIG. 1 to FIG. 3, and FIG. 6, a bionic Australian thorny devil grinding wheel is provided.

The bionic Australian thorny devil grinding wheel 1 is described in detail in conjunction with accompanying drawings.

Referring to FIG. 1, the bionic Australian thorny devil grinding wheel 1 includes a matrix 2 and abrasive grains. A superhydrophobic layer is arranged on an outer peripheral surface of the matrix 2, and the abrasive grains are fixed to the outer peripheral surface of the matrix 2. The abrasive grains are prismatic with an isosceles trapezoidal bottom surface. An axis of the abrasive grain is distributed in a radial direction of the matrix 2. One end of the abrasive grain in an axial direction is connected to the outer peripheral surface of the matrix 2, and the other end is of a hydrophilic structure. Two adjacent abrasive grains are arranged at intervals to form hexagonal-prism-shaped abrasive grain clusters 3, and gaps are reserved between the adjacent abrasive grain clusters 3, such that a hexagonal surrounding flow channel is formed in a circumferential direction of each abrasive grain cluster 3.

Additionally, a middle flow channel is formed between two abrasive grains of the abrasive grain cluster 3, and the middle flow channel is located between side surfaces of corresponding isosceles trapezoid bottom edges of the two abrasive grains. The middle flow channel is tangentially distributed along the position of the outer peripheral surface of the matrix 2, and communicates with the surrounding flow channel.

In this embodiment, both the middle flow channel and the surrounding flow channel are semi-open capillary channels to exert capillary action with a tendency toward the hydrophilic structure to water inside the middle flow channel and the surrounding flow channel.

It should be noted that the middle flow channel and the surrounding flow channel adopt a structure mimicking surface of Australian thorny devil. A top end of each skin bulge of the Australian thorny devil is a hydrophilic zone without covering a wax layer, and other zones of a back portion are waxy hydrophobic zones. In this embodiment, the superhydrophobic layer on the outer peripheral surface of the matrix 2 is the hydrophobic zone, and the hydrophilic structure at the tail end of the abrasive grain is the hydrophilic zone. Droplets are adsorbed after making contact with the hydrophilic zone, causing the droplets in the hydrophilic zone to quickly grow to play a role of water collection. Meanwhile, microscopic capillaries on the skin of the Australian thorny devil can guide liquid to specific locations, just like the middle flow channel and the surrounding flow channel in this embodiment, which guide the water to the hydrophilic zone from the hydrophobic zone, thereby achieving directional transport.

The outer peripheral surface of the matrix 2 utilizes the superhydrophobic layer treated by silicon oil-thermal processing. The matrix 2 with the superhydrophobic layer and the hydrophilic abrasive grains act together to improve the cooling and lubricating efficiency.

The outer peripheral surface of the matrix 2 is covered with the abrasive grain clusters 3 arranged in array. As shown in FIG. 6, the abrasive grain clusters 3 are arranged in a honeycomb-like hexagon. Specifically, along a circular direction of the outer peripheral surface of the matrix 2, the abrasive grain clusters 3 are arranged at intervals into a plurality of columns, and the adjacent columns of abrasive grain clusters 3 are staggered.

By designing the grinding wheel matrix 2 and the abrasive grains, the middle flow channel and the surrounding flow channel are formed in the outer peripheral surface of the matrix 2, thereby limiting surface tension of the liquid. As shown in FIG. 2, when the liquid flows within the middle flow channel and the surrounding flow channel, transverse flowing of the liquid is limited by the superhydrophobic layer as a hydrophobic boundary, ensuring that the liquid flows in a required direction under rotation and capillary actions.

The self-conveying principle of the grinding fluid in this embodiment is as follows:

As shown in FIG. 3, a resultant force exerted on microdroplets of the grinding fluid in the conveying process is F=F_L+F_C+F_G+F_H.

The middle flow channel and the surrounding flow channel are the same in structure, and are collectively referred to as flow channels in subsequent analysis.

In the formula, F_L and F_C respectively denote the driving force Laplace pressure and the single flow channel capillary force during droplet conveying; F_H denotes the hysteresis resistance that the droplets need to overcome during conveying; and F_G denotes the droplet gravity.

Different contact areas result in different contact angles on front and back sides of the droplets, leading to the generation of the Laplace pressure F_L.

F_L is shown in the formula (1):

$\begin{array}{cc}{F}_L=\gamma L_{\mathrm{TCL}}\left(\cos {\theta }_f-\cos {\theta }_b\right)& \left(1\right)\end{array}$

In the formula, γ denotes the surface tension of water; L_TCL denotes the length (μm) of a three-phase contact line; and θ_f and θ_b respectively denote the front contact angle and the back contact angle of the droplets.

The single flow channel capillary force F_C is shown in the formula (2):

$\begin{array}{cc}{F}_c=\gamma \left[\left(\cos \theta -1\right)a+2\cos \theta h\right]& \left(2\right)\end{array}$

In the formula, a denotes the flow channel width (μm); h denotes the microtexture flow channel height (μm); and θ denotes the surface contact angle of the droplets.

During droplet conveying, the hysteresis resistance F_H that the droplets need to overcome is shown in the formula (3):

$\begin{array}{cc}{F}_H=\frac{1}{2}{C}_D\rho v^{2}A& \left(3\right)\end{array}$

In the formula, C_D denotes the drag coefficient; ρ denotes the density (g/cm³) of the droplets; ν denotes the conveying rate (cm/s); and A denotes the cross-sectional area (cm²) of the droplets.

The droplet gravity F_G is shown in the formula (4):

$\begin{array}{cc}{F}_G=\frac{4}{3}\pi R_0^3\rho g& \left(4\right)\end{array}$

As the size of the microdroplets increases, the droplet conveying rate is reduced, resulting in a decrease in hysteresis resistance F_H. Simultaneously, the front contact angle θ_f of the liquid and the length L_TCL of the three-phase contact line are increased, and the back contact angle θ_b is reduced. The Laplace pressure F_L is increased, and the driving force exerted on the droplets is greater than the resistance, i.e., F=F_L+F_C−F_H−F_G>0, achieving droplet self-conveying.

In this embodiment, the hydrophilization principle of the abrasive grain clusters 3 arranged on the bionic Australian thorny devil grinding wheel 1 in a honeycomb-like hexagon is as follows:

• • according to a Cassie model,

$\begin{array}{cc}\cos {\theta }_C=f_{\mathrm{LS}}\cos {\theta }_{\mathrm{LS}}+f_{LV}\cos {\theta }_{LV}& \left(5\right)\end{array}$

In the formula, f_LS and f_LV respectively denote the area fractions of a liquid-solid contact interface and a liquid-gas contact interface, where f_LS+f_LV=1. θ_LS and θ_LV respectively denote the liquid-solid contact angle and the liquid-gas contact angle.

Compared with a conventional structure surface, the honeycomb-like hexagonal structure increases the solid-liquid contact area, and the three-phase contact line of the droplets on the surface of the structure changes, thereby increasing the Laplace pressure in the droplets, driving the droplets to spread, reducing the surface contact angle, and keeping physical stability of a liquid film.

The abrasive grains are chamfered corresponding to side ridges of prisms. Meanwhile, the droplets on the surface of the honeycomb-like hexagonal structure can diffuse all around along the flow channel to overcome the resistance generated by pinning of the three-phase contact line, such that the surface of the bionic Australian thorny devil grinding wheel 1 has super hydrophilicity, the grinding fluid stays on the surface of the bionic Australian thorny devil grinding wheel 1, and the physical stability of the liquid film is kept.

Embodiment 2

In a typical embodiment of the present disclosure, as shown in FIG. 1 to FIG. 3, and FIG. 6, a grinding device is provided.

The bionic Australian thorny devil grinding wheel 1 in Embodiment 1 is utilized.

The bionic Australian thorny devil grinding wheel 1 is externally provided with a grinding wheel guard 4. A minimum quantity lubrication nozzle 5 is connected to a grinding fluid conveying pipeline 6 and a compressed air conveying pipeline 7. A grinding fluid source is connected to the grinding fluid conveying pipeline 6. The compressed air conveying pipeline 7 is connected to a pressure air source.

Ultrasonic vibration enhances the infiltrating property of the grinding fluid on the bionic grinding wheel and the convective heat transfer coefficient of the grinding fluid, thereby enhancing the heat transfer capacity and lubricating capacity of cooling liquid. As shown in FIG. 2, one side of a tangential amplitude-changing mechanism of an ultrasonic vibrator 8 is connected to a radial amplitude changing mechanism, and the other side is connected to the workpiece. The radial amplitude changing mechanism and the tangential amplitude changing mechanism act together to form vibration of an arc track. By adjusting operating parameters of the radial amplitude changing mechanism and the tangential amplitude changing mechanism, a ground surface can be more uniform. Meanwhile, droplets staying on the surface subjected to ultrasonic vibration can explode into micro-mists of smaller droplets or form stable capillary waves on the surface, thereby enhancing the infiltrating characteristics of the grinding fluid.

The principle of enhancing the infiltrating of the grinding fluid by adding ultrasound in this embodiment is as follows:

According to the Jurin's law, the infiltrating height h_m of the grinding fluid without adding ultrasound is shown in the formula (6):

$\begin{array}{cc}{h}_m=\frac{2\sigma \cos \theta }{10^3\times \rho gr}& \left(6\right)\end{array}$

In the formula, h_m denotes the height (m) of liquid infiltration, σ denotes the surface tension of liquid, θ denotes the contact angle, ρ denotes the liquid density (Kg/m3), g denotes the gravitational acceleration (m/s2), and r denotes the width (m) of the middle flow channel and the surrounding flow channel.

After the addition of ultrasound, high-frequency and small-amplitude vibration is generated by ultrasonic waves, which in turn generates an extrusion die effect.

The additional static pressure intensity under the extrusion die effect is shown in the formula (7):

$\begin{array}{cc}{P}_j=\frac{1}{r}{u}^2\rho \frac{A_0^2}{10^3\times d_0}{\alpha }^2& \left(7\right)\end{array}$

In the formula, α denotes the extrusion die constant, u denotes the sound velocity (m/s), A₀ denotes the amplitude (dB) of ultrasonic waves, and d₀ denotes the liquid level height (m).

The infiltrating height h_j under the extrusion die effect is shown in the formula (8):

$\begin{array}{cc}{h}_j=\frac{p_j}{\rho g}\frac{1}{r}{u}^2\frac{A_0^2}{10^3\times g{d}_0}{\alpha }^2& \left(8\right)\end{array}$

The total infiltrating height h_c of the cooling liquid after adding ultrasound is shown in the formula (9):

$\begin{array}{cc}{h}_c=h_m+h_j& \left(9\right)\end{array}$

Under the action of ultrasound, the total liquid infiltrating height is the sum of the original infiltrating height and the infiltrating height under the extrusion die effect, thereby further enhancing the conveying performance of the grinding fluid.

The principle of enhancing the heat transfer performance of the grinding fluid by adding ultrasound in this embodiment is as follows:

• • under the action of ultrasound, local tensile stress occurs in the cooling liquid, which forms a negative pressure. The decrease in pressure intensity causes gas dissolved in the grinding fluid to become supersaturated, escaping from the fluid and forming small bubbles. Under the action of the strong tensile stress, gas forms cavities within the fluid after escaping, which is referred to as an ultrasonic cavitation effect. The ultrasonic cavitation effect includes generation, expansion, oscillation, and collapse of cavitation bubbles. A large amount of energy can be released at the moment of cavitation bubble collapse. The impact effect generated by the energy is much greater than the impact effect of grinding, causing disturbances on a grinding flow field. The surface flow field of the workpiece transitions from laminar flow to turbulent flow, leading to an increase in the Reynolds number of the fluid.

The convective heat transfer coefficient h of the fluid is shown in the formula (10):

$\begin{array}{cc}h=\frac{N_{u}k}{L}& \left(10\right)\end{array}$

In the formula, N_u denotes the Nusselt number of the fluid, k denotes thermal conductivity (W/(m×k)), and L denotes the geometric length (m) of a heat transfer surface.

The Nusselt number N_u of the fluid is shown as:

$\begin{array}{cc}{N}_u=0.32{\mathrm{Re}}^{\frac{1}{2}}\times P{r}^{\frac{1}{3}}& \left(11\right)\end{array}$

In the formula, Re denotes the Reynolds number, and Pr denotes the Prandtl constant.

From the formulas (10) to (11), it can be observed that as the Reynolds number increases, the Nusselt number of the fluid increases, leading to an increase in the convective heat transfer coefficient of the fluid.

The minimum quantity lubrication nozzle 5 conveys the grinding fluid to a grinding zone in a mist spray manner. The hydrophilic abrasive grain clusters 3 on the surface of the bionic Australian thorny devil grinding wheel 1 first make contact with an atomized cooling medium. Based on a basic wettability principle, the cooling medium first condenses into microdroplets on the abrasive grain clusters 3, and the cooling medium not contact with the abrasive grain clusters 3 is sprayed onto the outer peripheral surface of the matrix 2 and is conveyed to the hydrophilic structure at the tail end of the abrasive grains through the middle flow channel and the surrounding flow channel to accelerate growth of the droplets at the abrasive grain clusters 3. Then, the droplets fall off under the gravity and the rotation of the bionic Australian thorny devil grinding wheel 1.

Embodiment 3

In another typical implementation of the present disclosure, as shown in FIG. 1, and FIG. 3 to FIG. 6, a process for preparing a bionic Australian thorny devil grinding wheel 1 is provided.

The bionic Australian thorny devil grinding wheel 1 in Embodiment 1 is obtained by the preparation process. The preparation process includes:

• • superhydrophobic treatment is performed on an outer peripheral surface of a matrix 2 to obtain a superhydrophobic layer;
  • abrasive grains are processed, such that a hydrophilic structure is formed at one end of the abrasive grain; and
  • the abrasive grains are paired to obtain abrasive grain clusters 3, the abrasive grains are adhered to the outer peripheral surface of the matrix 2 in a manner of the abrasive grain clusters 3, the adjacent abrasive grain clusters 3 are arranged at intervals, and a bionic Australian thorny devil flow channel is formed between the adjacent abrasive grains, and the abrasive grain clusters 3 are arranged in a bionic honeycomb structure.

Specifically, as shown in FIG. 4, the preparation process specifically includes the following steps.

1. Super-Hydrophobization on a Surface of the Grinding Wheel Matrix 2

A superhydrophobic coating is arranged on the outer peripheral surface of the matrix 2, silicon oil-thermal processing is adopted for super-hydrophobization, the coating of the matrix 2 is sequentially placed in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 5 min each, and then, a sample is dried for use later. Then, a silicon oil solution is dropwise added and dipped into a surface of the coating of the matrix 2, and the surface is placed on a heating plate to be heated for 10 min to ensure stable bond between the silicon oil and the surface. Through the silicon oil-thermal processing, functional groups with low surface energy in the silicon oil are deposited on the surface of the coating of the matrix 2 to form a hydrophobic layer, such that a contact angle of the grinding fluid on the matrix 2 is greater than 150 degrees, exhibiting excellent superhydrophobic performance.

2. Surface Groove Machining on the Matrix 2

As shown in FIG. 5, grooves is machined in the matrix 2 by spray-assisted laser, after dimension design of a bionic array structure is completed, a two-dimensional pattern is drawn by CAD software and saved in a DXF format to be imported into a laser device 9, and a light beam 10 emitted by the laser device 9 reaches a beam expander 12 through a reflector 11; and through the beam expander 12, the laser beam becomes more stable, and the spread width of the laser beam is enhanced. The enhanced light beam passes through an aperture 13 and a Glan prism 14 to control the offset distance of the light beam. Finally, the laser beam forms a uniform-sized focused light spot throughout a movable machining platform 16 through a focus lens 15, which is used for machining the grooves in the surface of the grinding wheel matrix 2, with a machining depth of D μm. By controlling different parameters of the laser and scanning the surface of the matrix 2 to change a micro-scale structure of the surface of the matrix, the surface grooves like a honeycomb hexagon are formed.

Before the start of preparation, the matrix 2 is sequentially placed in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 5 min each, and then a sample is dried for use later. Selected laser parameters are as follows: the wavelength is 1064 nm, the pulse width is 45 ns, the power is 15 W, the frequency is 20 kHz, and the scanning speed is 100 mm/s. By increasing the number of times of laser scanning, the texture depth is increased. By adjusting various parameters of the laser, the matrix 2 is machined into a honeycomb-like hexagonal structure to keep the physical stability of a water film.

3. Abrasive Grain Hydrophilization

As shown in FIG. 6, according to a trapezoidal structure of the surface of the Australian thorny devil, the side length of an upper bottom surface of the abrasive grain is set to be a μm, the side length of a lower bottom surface is set to be b μm, the height is set to be c μm, the groove spacing is set to be d μm, and the structure depth is set to be h μm.

Diamond abrasive grains of the same size and the similar structure are selected, and surfaces of the diamond abrasive grains are roughened by soaking in chromic acid. According to the Young wetting equation:

$\begin{array}{cc}\cos {\theta }_Y=\frac{{\gamma }_{SV}-{\gamma }_{SL}}{{\gamma }_{LV}}& \left(12\right)\end{array}$

γ denotes the surface roughness, and based on the equation, it can be deduced that an increase in γ leads to a decrease in contact angle, thereby enhancing hydrophilicity. The roughened diamond abrasive grains exhibit hydrophilicity.

4. Combination of the Abrasive Grain Clusters 3 and the Hydrophobic Layer on the Surface of the Matrix 2

The electroplated abrasive grains are orderly arranged using a masking method, and a coordinate equation for the center of each abrasive grain cluster 3 is shown in the formula (13):

$\begin{array}{cc}\{\begin{array}{c}{\theta }_{ij}=\frac{2i\pi }{M}\\ Z_{ij}=ja\\ M=\frac{2r_s\pi }{a}\\ a=\sqrt{\frac{2r_{s}H\pi }{N}}\end{array}& \left(13\right)\end{array}$

θ_ij denotes the abrasive grain misalignment angle; i denotes the circumferential row number, and j denotes the axial row number (i=1, 2, 3, . . . , and M; and j=1, 2, . . . , and H/a); a denotes the abrasive grain spacing (mm); N denotes the total number of the abrasive grains; M denotes the circumferential total row number of the abrasive grains; Z_ij denotes the axial coordinates; and r_S denotes the grinding wheel radius, and H denotes the abrasive grain protrusion height.

A mask with array holes arranged orderly is formed through laser processing, and the mask is adhered to the matrix 2. Before adhering the mask, the surface of the matrix 2 is first subjected to degreasing and rust removal processes such as chemical degreasing, electrochemical degreasing, and acid pickling, thereby preventing the electroplated surface of the matrix 2 from being contaminated again.

Then, the abrasive grain clusters 3 are fixed into the orderly-arranged array holes through a binder. The thickness of the binder is 20% of the height of the diamond abrasive grains. The abrasive grains in each hole form the abrasive grain clusters 3.

The holes are in a shape of an inverted bowl, i.e., a big-end-down shape. This stacking shape provides a higher holding force for the abrasive grains, and it is not easy for the abrasive grains to fall off during operation. Through an electrodeposition method, the abrasive grains are preliminarily fixed, the mask is removed, and then electroplating for thickening is performed. The electro-deposited matrix 2 is subjected to ultrasonic cleaning for 5 min first, then, electroplate liquid is poured into an electroplating tank washed cleanly, and the pH value of the electroplate liquid is 3.0-5.0. In the electroplating process, a magnetic stirrer is adopted for continuous stirring, the electroplating time is 10 min, such that the coating thickness of an electroplated coating is 60% of the diameter of the abrasive grains, and the abrasive grain protrusion height is about ⅓ of the total height of the abrasive grains.

The abrasive grain clusters 3 are arranged in a hydrophilic bionic honeycomb hexagon. Due to the hexagonal structure, the surface of the grinding wheel has superhydrophilicity, thereby making water stay on the surface of the grinding wheel without volatilization and keeping the physical stability of a liquid film.

The foregoing descriptions are merely preferred embodiments of the present disclosure, but are not intended to limit the present disclosure. Those skilled in the art may make various modifications and variations to the present disclosure. Any modification, equivalent replacement, improvement, and the like made within the spirit and principle of the present disclosure shall fall within the scope of protection of the present disclosure.

Claims

1. A bionic Australian thorny devil grinding wheel, comprising: a matrix, having a superhydrophobic layer arranged on an outer peripheral surface; andabrasive grains which are prismatic with an isosceles trapezoidal bottom surface, wherein an axis of the abrasive grain is distributed in a radial direction of the matrix, one end of the abrasive grain in an axial direction is connected to the outer peripheral surface of the matrix, and the other end is of a hydrophilic structure; and two adjacent abrasive grains are arranged at intervals to form a hexagonal-prism-shaped abrasive grain cluster, and gaps are reserved between adjacent abrasive grain clusters, such that a hexagonal surrounding flow channel is formed in a circumferential direction of each abrasive grain cluster.

2. The bionic Australian thorny devil grinding wheel according to claim 1, wherein the outer peripheral surface of the matrix is covered with the abrasive grain clusters arranged in array, and the abrasive grain clusters are arranged in a honeycomb-like hexagon.

3. The bionic Australian thorny devil grinding wheel according to claim 2, wherein along a circular direction of the outer peripheral surface of the matrix, the abrasive grain clusters are arranged at intervals into a plurality of columns, and adjacent columns of the abrasive grain clusters are staggered.

4. The bionic Australian thorny devil grinding wheel according to claim 1, wherein a middle flow channel is formed between two abrasive grains of the abrasive grain cluster, and the middle flow channel is located between side surfaces of corresponding isosceles trapezoid bottom edges of the two abrasive grains.

5. The bionic Australian thorny devil grinding wheel according to claim 4, wherein the middle flow channel is tangentially distributed along a position of the outer peripheral surface of the matrix, and communicates with the surrounding flow channel.

6. The bionic Australian thorny devil grinding wheel according to claim 5, wherein both the middle flow channel and the surrounding flow channel are semi-open capillary channels to exert capillary action with a tendency toward a hydrophilic structure to water inside the middle flow channel and the surrounding flow channel.

7. The bionic Australian thorny devil grinding wheel according to claim 1, wherein the abrasive grains are chamfered corresponding to side ridges of prisms.

8. A grinding device, comprising the bionic Australian thorny devil grinding wheel according to claim 1.

9. A process for preparing the bionic Australian thorny devil grinding wheel according to claim 1, comprising: performing superhydrophobic treatment on the outer peripheral surface of the matrix to obtain the superhydrophobic layer;processing the abrasive grains, such that the hydrophilic structure is formed at the one end of the abrasive grain; andpairing the abrasive grains to obtain the abrasive grain clusters, adhering the abrasive grains to the outer peripheral surface of the matrix in a manner of the abrasive grain clusters, arranging the adjacent abrasive grain clusters at intervals, and forming a bionic Australian thorny devil flow channel between adjacent abrasive grains, wherein the abrasive grain clusters are arranged in a bionic honeycomb structure.

10. The process for preparing the bionic Australian thorny devil grinding wheel according to claim 9, wherein a masking method is adopted to adhere the abrasive grains to the matrix.

11. The bionic Australian thorny devil grinding wheel according to claim 9, wherein the outer peripheral surface of the matrix is covered with the abrasive grain clusters arranged in array, and the abrasive grain clusters are arranged in a honeycomb-like hexagon.

12. The bionic Australian thorny devil grinding wheel according to claim 11, wherein along a circular direction of the outer peripheral surface of the matrix, the abrasive grain clusters are arranged at intervals into a plurality of columns, and the adjacent columns of the abrasive grain clusters are staggered.

13. The bionic Australian thorny devil grinding wheel according to claim 9, wherein a middle flow channel is formed between two abrasive grains of the abrasive grain cluster, and the middle flow channel is located between side surfaces of corresponding isosceles trapezoid bottom edges of the two abrasive grains.

14. The bionic Australian thorny devil grinding wheel according to claim 13, wherein the middle flow channel is tangentially distributed along a position of the outer peripheral surface of the matrix, and communicates with the surrounding flow channel.

15. The bionic Australian thorny devil grinding wheel according to claim 14, wherein both the middle flow channel and the surrounding flow channel are semi-open capillary channels to exert capillary action with a tendency toward a hydrophilic structure to water inside the middle flow channel and the surrounding flow channel.

16. The bionic Australian thorny devil grinding wheel according to claim 9, wherein the abrasive grains are chamfered corresponding to side ridges of prisms.