A method for laser in-situ assisted grinding of a single crystal diamond conical indenter

Abstract

The present invention discloses a method for laser in-situ assisted grinding of a single crystal diamond conical indenter. This method selects an appropriate laser path according to the different cone angles and tip blunt round characteristics of the single crystal diamond conical indenter. The laser beam emitted by the laser enters from the shank end of the single crystal diamond conical indenter. When rotating to grind the single crystal diamond conical surface, the laser beam undergoes total internal reflection inside the single crystal diamond, enabling the single crystal diamond cone to absorb most of the laser energy. When grinding the tip blunt round of the single crystal diamond, the laser beam is focused on the tip of the single crystal diamond conical indenter, ultimately reducing the hardness of the single crystal diamond, weakening the influence of anisotropy, and uniformly grinding it through a grinding disk, solving the defects such as edges and corners on the conical surface, tip blunt round notches, irregularities, etc. after grinding the single crystal diamond conical indenter, and finally obtaining a high-precision single crystal diamond conical indenter, improving the grinding quality and efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of single-crystal diamond grinding and polishing, and particularly relates to a method for laser in-situ assisted grinding of a single-crystal diamond conical indenter. Background Art

[0002] Single-crystal diamond has the advantages of extremely high hardness, wear resistance, low friction coefficient, corrosion resistance, etc., and is widely used in the fields of manufacturing machining tools, optical windows, etc. Single-crystal diamond is a typical hard and brittle material with high hardness, brittle fracture mode, and obvious anisotropy. During grinding, the grinding rates of different crystal planes are different. The grinding rate of the (110) crystal plane is the highest, and the grinding rate of the (111) crystal plane is the lowest. There are also significant differences in the grinding rates in different directions on the same crystal plane. Therefore, the prior art needs to select the easy-to-grind direction for grinding, or improve the grinding rate through means such as lasers and ultrasounds to improve the grinding efficiency and quality of single-crystal diamond tools. However, for single-crystal diamond tools with rotational symmetry made of single-crystal diamond, such as single-crystal diamond conical indenters, the single-crystal diamond needs to rotate during grinding, and different crystal planes and different directions are ground alternately, making the grinding process complex. Eventually, convex ridges will be formed on the conical surface, which is more obvious closer to the conical tip, and there will be defects such as notches and irregular shapes at the blunt tip of the cone, resulting in a low shape error grade and poor surface quality of the processed single-crystal diamond conical indenter. Therefore, there is an urgent need for a new processing method in the prior art to solve the grinding problem of single-crystal diamond conical indenters. Summary of the Invention

[0003] To solve the above problems, the present invention provides a method for laser in-situ assisted grinding of a single-crystal diamond conical indenter. A laser beam is injected into the single-crystal diamond conical indenter, so that the single-crystal diamond body absorbs part of the energy and heats up, reducing the hardness and weakening the influence of anisotropy, which can effectively solve the problems in the prior art that when processing single-crystal diamond with a rotational symmetry shape, such as a single-crystal diamond conical indenter, there are defects such as edges and corners, tip breakage, and irregularity on the processed conical surface, with a low shape error grade and poor surface quality.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for laser in-situ assisted grinding of a single-crystal diamond conical indenter includes the following steps implemented sequentially:

[0006] S1. Rough grind a single-crystal diamond conical indenter with a hollow tool shank and fix it with a fixture, and select a suitable grinding conical surface and a laser path for grinding the blunt tip of the cone according to the cone angle of the required single-crystal diamond conical indenter;

[0007] S2. Adjust the laser lens so that the laser emitted by the laser matches the laser path when grinding the selected grinding conical surface. Start the grinding process. The grinding disc rotates, the laser lens remains stationary and continuously outputs laser, and the fixture drives the single-crystal diamond conical indenter to rotate around its own axis to grind the conical surface of the single-crystal diamond conical indenter.

[0008] S3. Adjust the laser lens so that the laser emitted by the laser matches the laser path when grinding the blunt tip of the grinding tip. Start the grinding process. The grinding disc rotates, the fixture drives the single-crystal diamond conical indenter to rotate around its own axis, and the laser lens and the fixture swing together around the tip of the single-crystal diamond conical indenter to grind the blunt tip of the single-crystal diamond conical indenter.

[0009] Preferably, the laser path when grinding the conical surface is selected according to the cone angle of the single-crystal diamond conical indenter, specifically:

[0010] When the cone angle ɑ of the ground single-crystal diamond conical indenter is ≥81.072°, the incident angle θ1 of the laser beam emitted by the laser entering from the shank end of the single-crystal diamond conical indenter needs to satisfy sinθ1 ≤ 2.17cos(ɑ / 2) - 0.907sin(ɑ / 2);

[0011] When the cone angle ɑ of the ground single-crystal diamond conical indenter is 60° ≤ ɑ ≤ 81.072°, the incident angle θ1 of the laser beam emitted by the laser entering from the shank end of the single-crystal diamond conical indenter needs to satisfy sinθ1 ≤ 2.17cos(3ɑ / 2) - 0.907sin(3ɑ / 2);

[0012] When the cone angle ɑ of the ground single-crystal diamond conical indenter is ≤60°, the incident angle θ1 of the laser beam emitted by the laser entering from the shank end of the single-crystal diamond conical indenter needs to satisfy sinθ1 ≥ 2.17cos(3ɑ / 2) - 0.907sin(3ɑ / 2).

[0013] Preferably, the laser path when grinding the blunt tip is that the laser beam is perpendicular to the single-crystal diamond conical indenter, the focus is located at the tip of the single-crystal diamond conical indenter, and the focal length d is obtained by d = f0 + h0(1 - tan(arcsin(sin(arctan(R0 / f0)) / n0)) / tan(R0 / f0));

[0014] Where f0 represents the initial focal length of the laser lens, h0 represents the axial height of the single-crystal diamond conical indenter, R0 represents the initial spot diameter of the laser beam, and n0 represents the refractive index of the single-crystal diamond.

[0015] Preferably, the laser lens and the fixture swing together with the tip of the single-crystal diamond conical indenter as the center. The swing angle β is related to the cone angle of the single-crystal diamond conical indenter, and the swing angle β satisfies: π / 2 - ɑ / 2 ≤ β ≤ π / 2.

[0016] The beneficial effects of using the present invention are as follows:

[0017] In the present invention, a laser is incident on the single-crystal diamond conical indenter, and a suitable laser path is selected according to different cone angles and tip blunt circles of the ground single-crystal diamond conical indenter. When grinding the conical surface, the incident angle of the laser beam is adjusted to make the laser undergo total internal reflection along the axial direction inside the diamond and point to the tip of the single-crystal diamond indenter. The single-crystal diamond body absorbs the laser energy and heats up, weakening the influence of anisotropy, and finally realizing high-quality grinding of the conical surface of the single-crystal diamond conical indenter.

[0018] During the grinding process, the fixture drives the single-crystal diamond conical indenter to rotate along its own axis, while the laser lens remains stationary. Therefore, the laser beam is dynamically uniform inside the single-crystal diamond conical indenter, enabling the single-crystal diamond body to absorb the laser energy and heat up evenly, avoiding problems such as thermal stress and even carbonization caused by excessive local temperature. When grinding the tip blunt circle, the laser beam is directly focused on the tip of the single-crystal diamond conical indenter, with a small heat-affected zone. The single-crystal diamond absorbs the laser energy and heats up, reducing its hardness, weakening the influence of anisotropy, and improving the efficiency and quality of grinding the tip blunt circle. The technical solution provided by the present invention solves the problem that it is difficult to process a single-crystal diamond into a rotationally symmetric shape, and improves problems such as edges, local protrusions, or defects on the rotationally symmetric surface after processing, as well as problems such as missing corners and irregular shapes caused by brittle fracture of the single-crystal diamond at the rotationally symmetric tip. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of grinding the conical surface of the single-crystal diamond conical indenter of the present invention.

[0020] Figure 2 It is a schematic diagram of grinding the tip blunt circle of the single-crystal diamond conical indenter of the present invention.

[0021] Figure 3 It is a laser path diagram when grinding the conical surface of the single-crystal diamond conical indenter.

[0022] Figure 4 It is a laser path diagram when grinding the tip blunt circle of the single-crystal diamond conical indenter.

[0023] In the figure: 1 - laser lens; 2 - fixture; 3 - single-crystal diamond conical indenter; 4 - grinding disc; β - swing angle. θ1 - incident angle of laser beam; θ2 - refraction angle of laser beam; θ3 - reflection angle of laser beam; θ4 - secondary reflection angle of laser beam; α - cone angle of single-crystal diamond conical indenter. f0 - initial focal length of laser lens; h0 - axial height of single-crystal diamond conical indenter; R0 - initial spot diameter of laser beam; d - actual focal length of laser lens. Detailed implementation manners

[0024] To make the objectives, technical solutions and advantages of the present technical solution clearer and more understandable, the present technical solution will be further described in detail below in combination with specific implementation manners. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present technical solution.

[0025] As Figure 1 、 Figure 2 shown, this embodiment proposes a method for laser in-situ assisted grinding of a single-crystal diamond conical indenter, including the following steps implemented sequentially:

[0026] S1. A single-crystal diamond conical indenter 3 with a hollow shank is rough-ground and fixed by a fixture 2. A suitable grinding conical surface and a laser path with a blunt tip of the grinding are selected according to the cone angle of the required single-crystal diamond conical indenter 3.

[0027] S2. The laser lens 1 is adjusted so that the laser emitted by the laser is matched with the laser path when grinding the selected grinding conical surface. The grinding process is started. The grinding disc 4 rotates, the laser lens 1 remains stationary and continuously outputs laser, and the fixture 2 drives the single-crystal diamond conical indenter 3 to rotate around its own axis to grind the conical surface of the single-crystal diamond conical indenter 3.

[0028] As Figure 4 shown, S3. The laser lens 1 is adjusted so that the laser emitted by the laser is matched with the laser path when grinding the blunt tip of the selected grinding. The grinding process is started. The grinding disc 4 rotates, the fixture 2 drives the single-crystal diamond conical indenter 3 to rotate around its own axis, and the laser lens 1 and the fixture 2 swing together around the tip of the single-crystal diamond conical indenter 3 to grind the blunt tip of the single-crystal diamond conical indenter 3.

[0029] As Figure 3 shown, the laser path when grinding the conical surface is selected according to the cone angle of the single-crystal diamond conical indenter 3, specifically:

[0030] When the cone angle ɑ of the ground single-crystal diamond conical indenter is ≥ 81.072°, the incident angle θ1 of the laser beam emitted by the laser entering from the shank end of the single-crystal diamond conical indenter 3 needs to satisfy sinθ1 ≤ 2.17cos(ɑ / 2) - 0.907sin(ɑ / 2);

[0031] When the cone angle ɑ of the ground single-crystal diamond cone indenter satisfies 60°≤ɑ≤81.072°, the incident angle θ1 of the laser beam emitted by the laser into the single-crystal diamond cone indenter from the end of the tool shank 3 should satisfy sinθ1≤2.17cos(3ɑ / 2)-0.907sin(3ɑ / 2).

[0032] When the cone angle ɑ of the ground single-crystal diamond cone indenter satisfies ɑ≤60°, the incident angle θ1 of the laser beam emitted by the laser into the single-crystal diamond cone indenter from the end of the tool shank 3 should satisfy sinθ1≥2.17cos(3ɑ / 2)-0.907sin(3ɑ / 2).

[0033] In the above process, the laser beam emitted by the laser lens 1 enters the single-crystal diamond cone indenter 3. The laser beam refracts and forms the laser beam incident angle θ1 and the laser beam refraction angle θ2. The laser beam is reflected by the conical outer contour surface of the single-crystal diamond cone indenter 3 to form the laser beam reflection angle θ3, and is reflected again to form the laser beam secondary reflection angle θ4.

[0034] The laser path when grinding the tip to be blunt is that the laser beam is incident perpendicular to the single-crystal diamond cone indenter 3, and the focus is located at the tip of the single-crystal diamond cone indenter 3. The focal length d is obtained by d=f0+h0(1-tan(arcsin(sin(arctan(R0 / f0)) / n0)) / tan(R0 / f0));

[0035] Where f0 represents the initial focal length of the laser lens 1, h0 represents the axial height of the single-crystal diamond cone indenter 3, R0 represents the initial spot diameter of the laser beam, and n0 represents the refractive index of the single-crystal diamond.

[0036] The laser lens 1 and the fixture 2 swing together with the tip of the single-crystal diamond cone indenter 3 as the center. The swing angle β is related to the cone angle ɑ of the single-crystal diamond cone indenter, and the swing angle β satisfies: π / 2-ɑ / 2≤β≤π / 2.

[0037] The above content is only the preferred embodiment of the present invention. For those of ordinary skill in the art, according to the idea of the present technical content, many changes can be made in the specific implementation manner and application scope. As long as these changes do not depart from the concept of the present invention, they all belong to the protection scope of this patent.

Claims

1. A method for laser in-situ assisted grinding of a single crystal diamond conical indenter, characterized in that: Including the following steps implemented sequentially: S1. A single-crystal diamond conical indenter with a hollow shank is roughly ground and fixed by a fixture. Select a suitable grinding conical surface and the laser path for rounding the tip of the grinding according to the cone angle of the required single-crystal diamond conical indenter; S2. Adjust the laser lens of the laser so that the laser emitted by the laser matches the laser path when grinding the selected conical surface. Start the grinding process. The grinding disc rotates, the laser lens remains stationary and continuously outputs laser, and the fixture drives the single-crystal diamond conical indenter to rotate around its own axis to grind the conical surface of the single-crystal diamond conical indenter; S3. Adjust the laser lens of the laser so that the laser emitted by the laser matches the laser path when rounding the tip of the grinding. Start the grinding process. The grinding disc rotates, the fixture drives the single-crystal diamond conical indenter to rotate around its own axis, and the laser lens and the fixture swing together with the tip of the single-crystal diamond conical indenter as the center to grind the rounding of the tip of the single-crystal diamond conical indenter; The laser path when grinding the conical surface is selected according to the cone angle of the single-crystal diamond conical indenter. Specifically: When the cone angle ɑ of the ground single-crystal diamond conical indenter is ɑ≥81.072°, the incident angle θ1 of the laser beam emitted by the laser entering from the shank end of the single-crystal diamond conical indenter needs to satisfy sinθ1≤2.17cos(ɑ / 2)-0.907sin(ɑ / 2); When the cone angle ɑ of the ground single-crystal diamond conical indenter is 60°≤ɑ≤81.072°, the incident angle θ1 of the laser beam emitted by the laser entering from the shank end of the single-crystal diamond conical indenter needs to satisfy sinθ1≤2.17cos(3ɑ / 2)-0.907sin(3ɑ / 2); When the cone angle ɑ of the ground single-crystal diamond conical indenter is ɑ≤60°, the incident angle θ1 of the laser beam emitted by the laser entering from the shank end of the single-crystal diamond conical indenter needs to satisfy sinθ1≥2.17cos(3ɑ / 2)-0.907sin(3ɑ / 2); The laser path when rounding the tip of the grinding is that the laser beam is perpendicular to the single-crystal diamond conical indenter and the focus is located at the tip of the single-crystal diamond conical indenter.

2. The method for laser in-situ assisted grinding of a single-crystal diamond conical indenter according to claim 1, wherein: The focal length d is obtained by d = f0 + h0(1 - tan(arcsin(sin(arctan(R0 / f0)) / n0)) / tan(R0 / f0)); Where f0 represents the initial focal length of the laser lens, h0 represents the axial height of the single-crystal diamond conical indenter, R0 represents the initial spot diameter of the laser beam, and n0 represents the refractive index of the single-crystal diamond.

3. The method for laser in-situ assisted grinding of a single crystal diamond conical indenter according to claim 1, characterized in that: The laser lens and the fixture swing together with the tip of the single-crystal diamond conical indenter as the center, and the swing angle β is related to the cone angle of the single-crystal diamond conical indenter. The swing angle β satisfies: π / 2 - ɑ / 2≤β≤π / 2.

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