A method and device for preparing abrasive textured diamond grinding wheel

Abstract

The present invention discloses a method and device for preparing a diamond grinding wheel with textured abrasive grains; the existing diamond grinding wheel is formed by bonding diamond abrasive grains with a binder, and it is difficult to process an ideal surface micro-texture morphology; the present invention forms a diamond coating layer on the outer surface of a metal substrate by chemical vapor deposition, and performs laser ablation, thereby processing a regular diamond micro-texture morphology, thereby improving the grinding quality. In addition, the present invention obtains a diamond grinding wheel with a complex surface morphology by chemically vapor depositing a diamond coating layer on the surface of a metal substrate that matches the surface to be ground, thereby improving the efficiency and accuracy of grinding complex surfaces; at the same time, the diamond coating layer formed by chemical vapor deposition is an integrated structure at the molecular level, which can greatly improve the wear resistance of the diamond grinding wheel compared to a conventional grinding wheel in which each abrasive grain is an independent structure, and alleviate or even eliminate the problem of reduced grinding accuracy caused by the reduction of the grinding wheel.

Description

Technical Field

[0001] The invention belongs to the technical field of high-efficiency precision machining of diamond grinding tools, and specifically relates to a method and device for preparing abrasive grain textured diamond grinding wheels. Background Art

[0002] Diamond crystal belongs to the cubic system and has a face-centered cubic unit cell structure. Each carbon atom is arranged in SP 3 The hybrid orbital forms a covalent bond with four other carbon atoms. This special structure gives it extremely high hardness, thermal conductivity and excellent chemical stability, and is widely used in the field of cutting / grinding tools. In existing research, the surface texturing of diamond mainly includes: square / circular array protrusions or pits, grooves with different contours such as elliptical, corrugated, and cross, and surface periodic corrugated textures. Therefore, how to process low-damage texturing with different characteristic parameters on the diamond surface and realize its controllable processing is of great significance to improving the processing performance of diamond abrasives.

[0003] Pulse laser has the excellent characteristics of high energy density, good controllability, fast speed and high precision, which can realize precision micro-machining of diamond. Laser surface micro-machining is to use a high-energy-density laser beam to locally irradiate the surface of the workpiece, so that the irradiated surface layer of the workpiece is vaporized or chemically reacted to remove the material, and the impact and damage to the surface properties are small, and the surface micro-texture can be quickly etched. With the continuous advancement of ultrashort pulse laser technology, its process and mechanism of action with diamond and its application in diamond texturing processing have received more attention.

[0004] Traditional diamond grinding tools have the problems of difficult to control the arrangement of surface abrasive grains and poor wear resistance. At the same time, when processing textures on the surface of diamond grinding wheels with special shapes, there is no method to process specific, neatly arranged, uniformly textured abrasive grains. It is very difficult to process grooves with different contours such as elliptical, corrugated, and cross, and there is no unified processing mode. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for preparing an abrasive textured diamond grinding wheel to address the problems of difficult control of abrasive distribution and poor wear resistance on the surface of traditional diamond molds. A diamond grinding wheel with a target surface micro-texture is processed by chemical vapor deposition in combination with laser scanning ablation.

[0006] In a first aspect, the present invention provides a method for processing a micro-textured CVD diamond grinding wheel, which comprises the following steps:

[0007] Step 1: Form a diamond coating layer on a rotating metal substrate that matches the shape of the processed surface by chemical vapor deposition to obtain a rotating diamond grinding wheel embryo.

[0008] Step 2: According to the generatrix of the diamond wheel blank, set the target moving path of the laser emission point of the laser scanning; any point on the target moving path corresponds to a processed point on the generatrix of the grinding wheel; the distance from the target moving path to the processed point remains unchanged. Any point on the target moving path corresponds to a laser emission direction; the laser emission direction is perpendicular to the tangent of the processed point on the generatrix of the grinding wheel.

[0009] Step 3: According to the groove shape in the target micro-texture, the grinding wheel speed is matched with the laser scanning speed. The diamond grinding wheel blank is rotated around its own axis, and the laser is used to move along the target moving track and adjust the laser emission direction. The laser is scanned back and forth on the diamond grinding wheel blank to process the grooves corresponding to the target micro-texture and obtain a micro-textured CVD diamond grinding wheel.

[0010] Preferably, before laser scanning processing, laser processing parameters matching the diamond cover layer are obtained by ablation experiment. The laser processing parameters include laser energy and scanning speed.

[0011] Preferably, the specific process of the ablation experiment is: the diamond layer is processed by laser with different laser energies; based on the processing results, the laser energy threshold that can ablate the CVD diamond surface is obtained; the laser energy is determined by the laser scanning frequency and the laser power; based on the laser energy threshold, the diamond layer groove ablation test is performed at different scanning speeds to determine the optimal scanning speed.

[0012] Preferably, the error between the distance from the target moving path to the processed point and the preset laser emission length h is less than or equal to 0.001h. The error between the angle between the laser emission direction and the tangent line of the processed point and 90° is less than or equal to 0.09°.

[0013] Preferably, in step 2, the process of obtaining the target moving path is to sample points on the grinding wheel generatrix; each sampling point is along its normal direction away from the grinding wheel axis, and a trajectory key point with a distance of the laser emission length h is taken. All trajectory key points are fitted to obtain the target moving path.

[0014] Preferably, during the processing, the laser is driven by the robot arm to move along the target moving trajectory; the laser emission direction of the laser is adjusted by the emission galvanometer at the laser emission end of the laser.

[0015] Preferably, the grooves in the target micro-texture in step 3 are in a grid shape, and the abrasive grain structure is arranged in a matrix on the outer surface of the diamond cover layer. During the process of machining a groove, the diamond wheel blank rotates unidirectionally, and the laser moves from one end of the diamond wheel blank to the other end along the target moving trajectory to complete a cycle of laser scanning. Each groove performs one or more cycles of laser scanning.

[0016] Preferably, the grooves in the target micro texture in step 3 are wavy; a plurality of wavy grooves are arranged in sequence along the axial direction of the grinding wheel. The target micro texture grooves are a plurality of wavy grooves; each wavy groove surrounds the circumference of the grinding wheel.

[0017] In a second aspect, the present invention provides a micro-textured CVD diamond grinding wheel, which is prepared by the aforementioned processing method.

[0018] Preferably, the thickness of the diamond coating layer is in the range of 5 to 20 μm. The groove depth of the target micro-texture is 2.5 to 5 μm.

[0019] Beneficial effects of the present invention:

[0020] 1. The present invention forms a diamond coating layer on the outer surface of a metal substrate by chemical vapor deposition and performs laser ablation to produce a regular diamond micro-texture morphology; compared with a conventional grinding wheel with irregularly distributed abrasive grains formed by bonding diamond particles, the present invention can produce a diamond grinding wheel with an optimal surface morphology according to the requirements of the ground material and the grinding surface, thereby improving the grinding quality.

[0021] 2. The present invention obtains a diamond grinding wheel with complex surface morphology by chemically vapor depositing a diamond coating on the surface of a metal substrate that matches the surface to be ground, thereby improving the efficiency and accuracy of grinding complex surfaces; at the same time, the diamond coating formed by chemical vapor deposition is an integrated structure at the molecular level, which can greatly improve the wear resistance of the diamond grinding wheel compared to conventional grinding wheels in which each abrasive grain is an independent structure, and alleviate or even eliminate the problem of reduced grinding accuracy caused by the reduction of the grinding wheel.

[0022] 3. The present invention is a unified processing method for textured abrasive grains on the surface of special morphology grinding wheels. It uses nanosecond laser processing to make the CVD diamond surface evaporate or thermally oxidize instantaneously, so as to achieve the purpose of rapid material removal; and obtains the optimal laser processing parameters for the diamond coating through ablation tests. The laser is combined with a robotic arm so that the laser can move along the target exciting trajectory, and the galvanometer can adjust the laser emission direction to perform equidistant vertical laser ablation on the rotating grinding wheel with complex surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of Example 1 of the present invention.

[0024] Figure 2 This is a schematic diagram of the rotating grinding wheel model and its generatrix constructed in Example 1 of the present invention.

[0025] Figure 3 Schematic diagram of the laser incident direction at different positions on the grinding wheel surface in Example 1 of the present invention.

[0026] Figure 4 This is a schematic diagram of laser scanning with different laser emission directions at different positions on the surface of a grinding wheel according to Example 1 of the present invention.

[0027] Figure 5 This is a simulation diagram of the micro-texture morphology of the grinding wheel surface formed in Example 1 of the present invention.

[0028] Figure 6 This is a microscopic magnified image of the grinding effect of the grinding wheel prepared in Example 1 of the present invention on cemented carbide.

[0029] Figure 7 This is a simulation diagram of the micro-texture morphology of the grinding wheel surface formed in Example 2 of the present invention.

[0030] Figure 8 This is a microscopic magnified image of the grinding effect of the grinding wheel prepared in Example 2 of the present invention on cemented carbide. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0033] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but is not intended to be a limitation of the present invention.

[0034] Example 1

[0035] A CVD diamond grinding wheel comprises a metal substrate and a diamond coating. The metal substrate is in the shape of a body of revolution, and the axial cross-section profile matches the surface to be processed; the diamond coating is formed by chemical vapor deposition on the outer surface of the metal substrate; the outer surface of the diamond coating is provided with micro-textured grooves. The micro-textured grooves are formed by laser scanning. In this embodiment, the micro-textured grooves are in a grid shape or a wave shape. The abrasive grain units formed by the grid shape can be either rectangular or rhombus-shaped.

[0036] like Figure 1 As shown, a CVD diamond grinding wheel processing method based on the combination of laser and mechanical arm and the combination of grinding wheel rotation and laser scanning includes the following steps:

[0037] Step 1: Figure 2 As shown, according to the surface shape and size of the workpiece being processed, the corresponding axial cross-section profile of the complex profile rotary grinding wheel is designed, and the three-dimensional model and generatrix shape of the grinding wheel are constructed. The diamond coating is formed on the metal substrate by chemical vapor deposition.

[0038] Step 2: Determine the laser processing parameters based on the grinding wheel point ablation and groove ablation experiments.

[0039] The specific process of the ablation experiment is: laser processing the diamond layer at different laser scanning frequencies and laser powers, and obtaining the damage threshold of the CVD diamond surface based on the processing results; the damage threshold specifically refers to the laser energy that can cause CVD diamond ablation. The laser energy corresponds to a specific laser scanning frequency and laser power. Based on the damage threshold, the diamond layer groove ablation experiment is carried out at different scanning speeds to determine the optimal scanning speed.

[0040] Step 3: According to the three-dimensional model of the grinding wheel, set the target moving path of the laser point and the orientation of the laser point at different positions on the moving path; any point on the target moving path corresponds to a processed point on the generatrix of the grinding wheel; the distance between any point on the target moving path and its corresponding processed point is equal.

[0041] Specifically, the process of determining the target moving path is to uniformly sample points on the generatrix of the three-dimensional model of the grinding wheel; each sampling point is along its normal direction away from the grinding wheel axis (i.e., the direction perpendicular to the tangent), and the position of the preset laser emission length h from the sampling point is taken as the trajectory key point. All trajectory key points are fitted to obtain the target moving path.

[0042] like Figure 3 and Figure 4As shown in the figure, any point on the target moving path corresponds to a set laser emission direction; the laser emission direction is perpendicular to the tangent of the corresponding processed point on the grinding wheel to ensure that the laser maintains a vertical incident state during the entire processing process. The laser emission direction is adjusted by the galvanometer.

[0043] In actual application processing, a slight laser tilt will not have a significant impact on the morphology of the grinding wheel abrasive grains. Therefore, in order to simplify the processing, the laser emission length and emission angle corresponding to different points in the laser point movement path are allowed to vary within an error of 0.1%.

[0044] In actual processing, the laser is driven by a multi-degree-of-freedom processing robot and moves along the target moving trajectory; the laser emission direction of the laser is adjusted by the emitting galvanometer at the laser emission end of the laser.

[0045] Step 4: Set the target texture shape on the grinding wheel surface, and match the grinding wheel rotation speed with the laser scanning speed so that the path of the laser ablation point on the grinding wheel is consistent with the groove on the target micro texture.

[0046] In this embodiment, the grooves on the target micro-texture are in a grid shape, so that abrasive particles arranged in a matrix shape are formed on the outer surface of the diamond cover layer.

[0047] When the grinding wheel rotates and the laser is stationary, grooves extending along the circumference of the grinding wheel can be processed; when the grinding wheel is stationary and the laser translates along the circumference of the grinding wheel, grooves extending along the axial direction of the grinding wheel can be processed; radial grooves and axial grooves are staggered to form a rectangular abrasive structure.

[0048] When the grinding wheel and the laser rotate in coordination, spiral grooves can be machined on the outer surface of the grinding wheel. Spiral grooves of different rotation directions are staggered to form a diamond-shaped abrasive grain structure.

[0049] During the speed matching process, the displacement speed of the laser is adjusted according to the changing trends of the diameter and normal angle (specifically the angle between the normal and the axis) at different positions on the grinding wheel, so that the grooves formed on the outer surface of the grinding wheel remain uniform.

[0050] In this embodiment, the diameter of the CVD diamond grinding wheel is 300 mm, the thickness of the diamond cover is 20 μm, and the processing process is as follows:

[0051] The laser used is a fiber laser with a laser power of 25W and a laser scanning speed of 700mm / s. Since the processing method of the present invention requires the combination of the rotation of the grinding wheel and the relative motion between the laser scanning, the scanning number is 1 and the laser pulse frequency is 50kHz.

[0052] In the experiment, a five-axis machining center was used to replace the three-axis robot arm, but only two of the axes were actually used. The combination method is to replace the end tool of the five-axis machining center with the end-emitting galvanometer of the fiber laser, which allows the laser to be emitted from the original tool head and uses the galvanometer to change the laser incident angle.

[0053] The laser processing system includes a five-axis machining center, a fiber laser, and a grinding wheel fixture. The five-axis machining center mainly controls the laser to keep the incident angle perpendicular to the grinding wheel surface when it is incident on the grinding wheel surface. The grinding wheel is clamped with a fixture so that the grinding wheel can rotate around the central axis, which simplifies the processing in conjunction with laser scanning.

[0054] like Figure 3 As shown, at each axial position i of the grinding wheel, the angle between the tangent and the center axis of the grinding wheel is recorded as θ[i]. The center axis of the grinding wheel is taken as the 0-degree position of the laser incidence. From a simple geometric relationship, it can be obtained that the laser incidence angle is 90-θ[i]. At each lateral position i, the distance of the surface relative to the center axis of the grinding wheel is a[i]. According to the shape of the imported grinding wheel section, in order to maintain vertical incidence and without the need for return motion when the end laser scans, the laser emission length h (that is, the distance between the laser emission point and the processing surface) is set to a constant value h, which can be horizontally displaced from the top. l 1 , vertical displacement l 2 , the laser incident angle at the end is 90-θ, three parameters control the laser scanning path, list the corresponding DH parameter table of the internal robot arm of the five-axis machining center, and the Jacobian matrix of the end as follows:

[0055]

[0056] This determinant represents the position determinant of the end relative to the base coordinate. According to the height h at any position vertically above the grinding wheel, l2 is obtained. The vertical position of this point can be obtained to obtain l1, and the slope of the tangent at this point can determine θ[i]. The position of the internal robot arm during scanning can be obtained to ensure vertical incidence of the laser.

[0057] During the processing, the laser scans from one end of the grinding wheel to the other end, and then immediately returns to scan. After the scanning is completed, the end delays t and the cycle begins again. One cycle is counted as one cycle when the laser returns to the initial starting point, and five cycles are processed. After the cycle processing is completed, the surface texture morphology of the obtained grinding wheel is observed using a microscope.

[0058] After confirming that the morphology was not damaged, the grinding wheel was placed in an acetone solution for ultrasonic vibration cleaning to remove the residual graphite phase on the surface of the diamond grinding wheel.

[0059] For processing other different textured shapes, due to the vertical end incidence achieved by the robot, the processing on the grinding wheel surface can be equivalent to the processing on the plane, and the rotation of the grinding wheel can be equivalent to the translation of the plane to design the processing surface.

[0060] The prismatic micro-textured abrasive grains processed in this embodiment are as follows: Figure 5 As shown; the obtained grinding wheel was used to grind cemented tungsten carbide WC / 6Co. When the grinding parameters were grinding speed 20m / s, feed speed 20m / min, and grinding depth 10μm, the ground surface was as shown in Figure 6 As shown; it can be found that the prepared textured grinding wheel is used to grind cemented carbide, and the grinding surface quality is good and there is less breakage. For the prismatic textured grinding wheel, the surface roughness is about 1.6μm, and for the wavy textured grinding wheel, the surface roughness is about 1.8μm.

[0061] Example 2

[0062] A CVD diamond grinding wheel processing method based on the combination of laser and mechanical arm and the combination of grinding wheel rotation and laser scanning. The difference between this embodiment and embodiment 1 is that the shape of the groove on the target micro-texture is different. In this embodiment, the target micro-texture grooves are multiple wavy grooves; each wavy groove extends along the circumferential reciprocating vibration of the grinding wheel. The wavy grooves are arranged in sequence at equal intervals along the axial direction of the grinding wheel. The axial distance between the crest and the trough of the wavy groove is less than the spacing between two adjacent wavy grooves, so that different wavy grooves are nested together.

[0063] In the process of processing wavy grooves, the amplitude of the wave shape (i.e. the maximum axial reciprocating distance) determines the periodic reciprocating displacement of the laser; when processing special-shaped grinding wheels, in order to ensure that wavy textured abrasive particles with similar shapes can be processed at different surface inclination angles, the maximum reciprocating distance should refer to the distance on the generatrix of the grinding wheel. The specific method is:

[0064] According to the amplitude of the wavy texture to be processed, for the convenience of processing, the tangent slope of the midpoint of the reciprocating displacement position is taken. The maximum reciprocating distance is the displacement distance on this tangent. At the same time, according to this distance and slope, the longitudinal l 2 The amount of reciprocating displacement.

[0065] According to the width and depth of the required wavy grooves, the grinding wheel speed and the frequency of the laser back and forth scanning are determined; according to the density of the required wavy texture, the spacing between each circle of wavy texture is determined. By repeating the processing, neatly arranged and regularly shaped textured abrasive grains can be processed on the entire grinding wheel surface.

[0066] After the laser scanning is completed, the residual graphite phase on the surface of the grinding wheel after laser processing is removed by mechanical vibration or tapping. After the processing is completed, the surface morphology of the CVD diamond after grinding can be detected using a laser confocal microscope.

[0067] The wavy micro texture processed in this embodiment is as follows Figure 7 As shown; the obtained grinding wheel was used to grind cemented carbide. When the grinding parameters were grinding speed 20m / s, feed speed 20m / min, and grinding depth 10μm, the ground surface was as follows Figure 8 As shown; it can be found that the prepared textured grinding wheel is used to grind cemented carbide, the grinding surface quality is better, there is less breakage, and the surface roughness is about 1.8μm.

[0068] Although the invention is described with reference to specific implementations in the present embodiment, it should be understood that these embodiments are merely examples of the principles and applications of the invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the different dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A method for processing a micro-textured CVD diamond grinding wheel, characterized in that: The following steps are involved: Step 1: forming a diamond coating layer on a rotating metal substrate matching the shape of the processed surface by chemical vapor deposition to obtain a rotating diamond grinding wheel embryo; Step 2: according to the generatrix of the diamond wheel blank, the target moving path of the laser emission point of the laser scanning is set; any point on the target moving path corresponds to a processed point on the generatrix of the grinding wheel; the distance from the target moving path to the processed point remains unchanged; any point on the target moving path corresponds to a laser emission direction; the laser emission direction is perpendicular to the tangent of the processed point on the generatrix of the grinding wheel; Step 3: According to the groove shape in the target micro-texture, the grinding wheel rotation speed is matched with the laser scanning speed; the diamond grinding wheel blank is rotated around its own axis, the laser is used to move along the target moving trajectory and the laser emission direction is adjusted, and the laser scanning is performed reciprocatingly on the diamond grinding wheel blank to process the groove corresponding to the target micro-texture, so as to obtain a micro-textured CVD diamond grinding wheel; The groove shape in the target micro-texture is wavy; in the process of processing the wavy groove, the amplitude of the wave shape determines the periodic reciprocating displacement of the laser; when processing the special-shaped grinding wheel, in order to ensure that the wavy textured abrasive particles with similar shapes can be processed at different surface inclination angles, the maximum reciprocating distance is the distance on the generatrix of the grinding wheel. The specific method is: According to the amplitude of the wavy texture to be processed, for the convenience of processing, the tangent slope of the midpoint of the reciprocating displacement position is taken, and the maximum reciprocating distance is the displacement distance on this tangent. At the same time, according to this distance and the slope, the longitudinal reciprocating displacement is calculated; The grinding wheel rotation speed and the frequency of laser back-and-forth scanning are determined according to the required width and depth of the wavy grooves; the spacing between each circle of wavy texture is determined according to the required density of the wavy texture.

2. A method for processing a micro-textured CVD diamond grinding wheel according to claim 1, characterized in that: Before laser scanning processing, laser processing parameters matching the diamond coating are obtained through ablation experiments; the laser processing parameters include laser energy and scanning speed.

3. A method for processing a micro-textured CVD diamond grinding wheel according to claim 2, characterized in that: The specific process of the ablation experiment is as follows: the diamond layer is processed by laser with different laser energies; based on the processing results, the laser energy threshold that can ablate the CVD diamond surface is obtained; based on the laser energy threshold, the diamond layer groove ablation test is performed at different scanning speeds to determine the optimal scanning speed.

4. The method for machining a micro-textured CVD diamond grinding wheel according to claim 1, characterized in that: The error between the distance from the target moving path to the processed point and the preset laser emission length h is less than or equal to 0.001h; the error between the angle between the laser emission direction and the tangent line of the processed point and 90° is less than or equal to 0.09°.

5. The method for machining a micro-textured CVD diamond grinding wheel according to claim 1, characterized in that: In step 2, the process of obtaining the target moving path is to sample points on the grinding wheel generatrix; each sampling point is along its normal direction away from the grinding wheel axis, and a trajectory key point with a distance of the laser emission length h is taken; all trajectory key points are fitted to obtain the target moving path.

6. A method for machining a micro-textured CVD diamond grinding wheel according to claim 1, characterized in that: During the processing, the laser moves along the target moving trajectory driven by the robotic arm; the laser emission direction of the laser is adjusted by the emitting galvanometer at the laser emission end of the laser.

7. A micro-textured CVD diamond grinding wheel, characterized in that: It is prepared by the processing method described in any one of claims 1 to 6.

8. A micro-textured CVD diamond grinding wheel according to claim 7, characterized in that: The thickness of the diamond covering layer is 5-20 μm; the groove depth of the target micro-texture is 2.5-5 μm.

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