A process method of pre-blasting and then processing for high-quality and high-efficiency processing of hard and brittle materials

Abstract

The application discloses a process method of sand blasting before machining for high-quality and high-efficiency machining of hard and brittle materials, and belongs to the technical field of precision machining of hard and brittle materials. In view of the problems of easy edge collapse, cracks and low machining efficiency of hard and brittle materials in cutting, sand blasting treatment is performed on the surface to be machined of a workpiece before mechanical cutting machining, a uniform micro-crack damage layer is formed in a controllable manner on the material surface layer by using the impact of high-speed abrasive particles, and the bonding strength of the surface layer is weakened; subsequent cutting machining is then performed, so that the material is mainly removed in brittleness and secondarily removed in ductility, the cutting force and tool wear are significantly reduced, defects such as edge collapse and cracks are inhibited, and the machining surface quality and machining efficiency are improved. The process is simple and has strong adaptability, and can be widely applied to the precision and high-efficiency cutting machining scenes of various hard and brittle materials such as ceramics, monocrystalline silicon and sapphire.

Description

Technical Field

[0001] This invention relates to a pre-blasting and post-machining process for high-quality and efficient machining of hard and brittle materials, belonging to the field of precision machining technology for hard and brittle materials. This application is mainly used for pretreatment of hard and brittle materials before cutting, introducing a controllable pre-damage layer on the material surface through sandblasting, thereby effectively reducing tool wear and extending tool life during subsequent cutting processes. Background Technology

[0002] Hard and brittle materials, due to their excellent properties such as high temperature resistance, high hardness, high strength, low density, and excellent oxidation and wear resistance, are widely used in high-end technology fields such as aerospace, nuclear engineering, rail transportation, and precision manufacturing. Generally, hard and brittle material components require machining to achieve the dimensional accuracy and surface quality requirements for assembly, with cutting being one of the most common material removal methods. However, due to their high hardness and low fracture toughness, machining hard and brittle materials such as ceramics, single-crystal silicon, and sapphire has always been a challenging problem. During cutting, severe tool wear and a sharp reduction in tool life are particularly prone to occur, accompanied by surface chipping and delamination damage to the workpiece, which adversely affects the assembly accuracy and performance of the components.

[0003] To improve the machinability of hard and brittle materials, scholars at home and abroad have conducted extensive research, with the main technical approaches including laser-assisted machining, ultrasonic-assisted machining, and optimization of tool geometry parameters.

[0004] Laser-assisted machining softens materials through localized heating to reduce cutting forces. However, this method involves expensive equipment, and the localized high temperatures can easily introduce thermal stress. For hard and brittle materials with uneven coefficients of thermal expansion, this can easily lead to the propagation of microcracks in the matrix, causing thermal damage, and ensuring heating uniformity is also difficult.

[0005] Ultrasonic-assisted machining reduces cutting forces by applying high-frequency vibrations to the cutting tool. However, studies have shown that its effect on reducing tool wear is limited: ultrasonic vibrations mainly act on the dynamic instantaneous contact during the cutting process. For superhard materials, tool wear is still mainly abrasive wear, which cannot fundamentally change the intense friction between the tool and high-hardness abrasive grains. The potential for improving tool life is limited, and the system is complex and costly.

[0006] Tool geometry optimization improves tool wear resistance by adjusting parameters such as the rake angle and clearance angle. However, this method comes at the cost of sacrificing cutting sharpness, leading to increased cutting forces and temperatures, which may exacerbate abrasive wear. Parameter optimization alone cannot overcome the physical limits of tool materials and is unlikely to significantly extend tool life.

[0007] Therefore, how to introduce controllable pre-damage into the surface of hard and brittle materials through mechanical means while avoiding thermal damage, so as to significantly reduce subsequent tool wear without affecting the service performance of the workpiece, remains an important problem that needs to be solved in the field of engineering applications of hard and brittle materials. Summary of the Invention

[0008] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0009] To address the problems of high equipment costs, high risk of thermal damage, limited improvement in tool life, and easy chipping, cracking, and low processing efficiency in cutting hard and brittle materials in existing technologies, the present invention aims to provide a pre-blasting and post-machining process for high-quality and high-efficiency machining of hard and brittle materials. This process introduces a controllable pre-damage layer on the material surface through mechanical means, which significantly reduces subsequent tool wear and extends tool life without affecting the workpiece's service performance.

[0010] The above-mentioned objectives of this application can be achieved through the following technical solutions: This application provides a process method for high-quality and high-efficiency machining of hard and brittle materials, which includes sandblasting the surface of the workpiece to be machined before machining, forming a micro-crack damage layer on the material surface through high-speed abrasive particle impact, and then performing subsequent machining.

[0011] In one exemplary embodiment, the depth of the microcrack damage layer is precisely controlled by controlling process parameters, so that the depth of the microcrack damage layer is controlled within the range of 5μm to 10μm, ensuring that the damage is limited to the material surface and does not affect the overall service performance of the workpiece.

[0012] In one exemplary embodiment, the process parameters include one or more of the following: blasting pressure, abrasive particle size, blasting time, and blasting angle.

[0013] In one exemplary embodiment, the sandblasting pressure is controlled between 0.2 MPa and 0.8 MPa.

[0014] In one exemplary embodiment, the abrasive particle size is controlled between 60 mesh and 200 mesh.

[0015] In one exemplary embodiment, the sandblasting time is controlled between 10 seconds and 60 seconds.

[0016] In one exemplary embodiment, the spray angle is controlled between 45° and 90°.

[0017] In one exemplary embodiment, the hard and brittle material includes ceramic, monocrystalline silicon, or sapphire.

[0018] In one exemplary embodiment, one or more of white fused alumina, brown fused alumina, and silicon carbide are used as blasting abrasives.

[0019] In one exemplary embodiment, for different types of hard and brittle materials, the sandblasting process parameters can be adjusted according to the material characteristics to achieve the best pre-damage effect.

[0020] The core of this invention lies in proposing a "damage before cutting" machining strategy: by introducing a mechanical damage layer on the surface of the material in advance, the difficulty of subsequent cutting is reduced, thereby extending the tool life.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: First, this invention introduces a controllable microcrack damage layer on the surface of hard and brittle materials through sandblasting, which reduces the cutting difficulty from the material perspective and changes the traditional approach of focusing only on the tool or processing method. It provides a brand-new solution for the cutting and machining of hard and brittle materials (especially SiC ceramic composites).

[0022] Secondly, the present invention uses a purely mechanical sandblasting process, which avoids the thermal stress damage problem in laser-assisted processing and does not introduce a heat-affected zone or recast layer inside the material, effectively ensuring the service performance of the workpiece.

[0023] Third, by precisely controlling the sandblasting process parameters, the present invention achieves controllable adjustment of the depth of the damaged layer, which not only ensures the pretreatment effect but also avoids excessive damage to the overall performance of the material, thus exhibiting good process controllability and stability.

[0024] Fourth, the cutting force of hard and brittle materials treated by the method of the present invention is significantly reduced in subsequent cutting processes, tool wear is significantly slowed down, tool life can be extended by more than 2 times, while defects such as chipping and cracking are suppressed, the surface quality and processing efficiency are improved, and the processing cost is reduced.

[0025] Fifth, the method and equipment of this invention are simple, low-cost, and easy to operate. They do not require modification of existing cutting and processing equipment and have good industrial application prospects and promotion value.

[0026] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0028] Figure 1 For the sandblasting process on the surface of a workpiece made of hard and brittle materials; Figure 2 This refers to the cutting process using a cutting tool. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0030] The present invention will be further described in detail below with reference to specific embodiments, but these embodiments should not be construed as limiting the present invention.

[0031] This invention addresses the problems of chipping, cracking, and low machining efficiency in cutting hard and brittle materials. It proposes a pre-blasting followed by machining process for high-quality and efficient machining of these materials. Before machining, the workpiece surface is blasted, utilizing the impact of high-speed abrasive particles to controllably form a uniform micro-crack damage layer on the material surface, weakening the surface bonding strength. Subsequent machining then focuses on removing brittleness primarily, with ductility removal as a secondary process. This significantly reduces cutting forces and tool wear, suppresses chipping and cracking defects, and improves surface quality and machining efficiency. This invention is simple, highly adaptable, and can be widely applied to precision and high-efficiency machining of various hard and brittle materials such as ceramics, monocrystalline silicon, and sapphire.

[0032] In some embodiments, the pre-blasting and post-processing method for high-quality and efficient processing of hard and brittle materials provided by the present invention includes: using a blasting device to blast the surface of the workpiece to be processed with sandblasting, and forming a microcrack damage layer with a certain depth on the surface of the material by impacting the material surface with high-speed jetting abrasive particles.

[0033] In some embodiments, the depth of the microcrack damage layer is controlled by adjusting the blasting pressure, abrasive particle size, blasting time, and blasting angle, so that it is within a controllable range, ensuring that the damage layer is limited to the material surface and does not affect the overall mechanical properties and service performance of the workpiece.

[0034] In some embodiments, a hard and brittle material workpiece that has undergone sandblasting pretreatment is machined. Because a microcracked damage layer has formed on the surface, the local strength and hardness of the material are reduced, the cutting force during the cutting process is decreased, and tool wear is significantly reduced.

[0035] The materials and instruments used in the examples and comparative examples are as follows: The SiC ceramic composite material was SIC-995, purchased from Shenzhen Dachuan Precision Ceramics Co., Ltd. The brown fused alumina is A-60, purchased from Shanghai Tuopu Electromechanical Co., Ltd. The pressure-type automatic sandblasting machine, model PS-8228, was provided by Shanghai Tuopu Electromechanical Co., Ltd. The resin-bonded diamond grinding head is SDM-120, supplied by Huizhou Jinshi Hongyuan Precision Tools Co., Ltd.

[0036] The testing method is as follows: Surface hardness: The Rockwell hardness tester (conical diamond indenter) was used for testing. The test load was 150 kgf. Five different points were tested for each sample, and the average value was taken as the final surface hardness value.

[0037] Roughness: The roughness was tested using a white light interferometer (model: WYKO NT9300). The test length was 4 mm, the sampling frequency was 100 Hz, and three different regions were tested for each sample. The average value was taken as the final roughness value (Ra).

[0038] Subsurface damage depth: The test was conducted using a metallographic microscope (model: DM2700M). After cutting, grinding, and polishing the sample along the direction perpendicular to the processed surface, it was etched with a metallographic etchant (hydrofluoric acid and nitric acid volume ratio 1:3). The thickness of the subsurface damage layer was observed and measured under a microscope. Three cross sections were tested for each sample, and the average value was taken as the final subsurface damage depth.

[0039] Cutting force: The dynamic force gauge (model: Kistler 9257B) was used for testing. The sample was fixed on the worktable of the force gauge and a resin-bonded diamond grinding head was used for cutting test. The cutting speed was 10m / min, the feed rate was 0.1mm / r, and the cutting depth was 0.01mm. The main cutting force, feed resistance and back force were collected in real time during the cutting process. Each sample was tested 3 times and the average value was taken as the final cutting force data.

[0040] Example 1 In this embodiment, SiC ceramic composite material was selected as the workpiece to be processed, with dimensions of 40mm × 40mm × 2mm. Brown corundum abrasive was used as the blasting medium, with a particle size of 100 mesh. The blasting process was carried out in a pressure-type automatic blasting machine with a blasting pressure of 0.5MPa, a blasting distance of 70mm, a blasting time of 25s, and a spray angle of 60°. The blasting gun scanned the workpiece's processing area at a uniform speed of 60 mm / s, forming a uniform microcrack damage layer with a thickness of approximately 9μm on the material surface, achieving controllable weakening of the SiC ceramic surface strength. Subsequently, a resin-bonded diamond grinding head was used for cutting, with a spindle speed of 10000r / min, a cutting depth of 0.1mm, and a feed rate of 100mm / min.

[0041] In this embodiment, the cutting force is 19N and the surface roughness Ra is 0.5μm. No chipping, corner breaking, or internal cracks occur during the machining process. Tool wear is reduced by 45%, and machining efficiency is increased by about 30%, effectively achieving high-quality and high-efficiency machining of SiC ceramic composite workpieces.

[0042] Example 2 This embodiment is similar to Embodiment 1, except that the abrasive particle size is adjusted to 80 mesh and the blasting time is 20 seconds. The performance test results are shown in Table 1.

[0043] Example 3 This embodiment is similar to Embodiment 1, except that the abrasive particle size is adjusted to 120 mesh and the blasting time is 30 seconds. The performance test results are shown in Table 1.

[0044] Comparative Example 1 This comparative example did not perform sandblasting on the SiC ceramic composite workpiece. Instead, it was directly machined using a resin-bonded diamond grinding head with a spindle speed of 10,000 r / min, a cutting depth of 0.1 mm, and a feed rate of 100 mm / min.

[0045] The cutting force in this comparative example is 28N, the surface roughness Ra is 1.2μm, and the machining process is prone to chipping, cracking, tool wear, and low machining efficiency.

[0046] Comparative Example 2 This comparative example is similar to Example 1, except that the sandblasting time is adjusted to 80s, while the abrasive particle size, sandblasting pressure, and cutting parameters are the same as in Example 1. After sandblasting, the surface hardness (HV) of this comparative example is 1700, the surface roughness (Ra) is 1.1μm, the subsurface damage depth is 25μm, the cutting force is 17N, and the surface roughness (Ra) after cutting is 0.6μm. Severe surface peeling and internal microcracks occurred during the machining process, and the tool wear reduction rate was only 50%. The damaged workpiece could not meet the usage requirements.

[0047] Table 1 As can be seen from the table above, in Example 2, the abrasive particle size was too small and the sandblasting time was too short, resulting in insufficient sandblasting weakening effect and slight edge chipping in subsequent cutting; in Example 3, the abrasive particle size was too large and the sandblasting time was too long. Although the cutting force was further reduced, the subsurface damage was too deep, and the workpiece was prone to surface peeling, affecting the processing quality; the parameter combination of Example 1 (abrasive particle size 100 mesh, sandblasting time 25s) can form a uniform and controllable microcrack damage layer on the surface of SiC ceramic, taking into account both sandblasting effect and cutting performance, with no obvious processing defects, and is the preferred combination.

[0048] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A process method for high-quality and efficient processing of hard and brittle materials, characterized by sandblasting followed by machining, wherein... This includes sandblasting the workpiece surface before machining, where high-speed abrasive particles impact the material surface to form a micro-crack damage layer before subsequent machining.

2. The process method according to claim 1, characterized in that, By controlling process parameters, the depth of the microcrack damage layer can be precisely controlled within the range of 5μm to 10μm, ensuring that the damage is limited to the material surface and does not affect the overall service performance of the workpiece.

3. The process method according to claim 2, characterized in that, The process parameters include one or more of the following: blasting pressure, abrasive particle size, blasting time, and blasting angle.

4. The process method according to claim 3, characterized in that, The sandblasting pressure is controlled between 0.2 MPa and 0.8 MPa.

5. The process method according to claim 3, characterized in that, The abrasive particle size is controlled between 60 mesh and 200 mesh.

6. The process method according to claim 3, characterized in that, The sandblasting time is controlled between 10 and 60 seconds.

7. The process method according to claim 3, characterized in that, The spray angle is controlled between 45° and 90°.

8. The process method according to any one of claims 1-7, wherein the hard and brittle material comprises ceramic, monocrystalline silicon, or sapphire.

9. The process method according to any one of claims 1-7, characterized in that, One or more of white fused alumina, brown fused alumina, and silicon carbide are used as blasting abrasives.

10. The process method according to any one of claims 1-7, characterized in that, For different types of hard and brittle materials, the sandblasting process parameters should be adjusted according to the material characteristics to achieve the best pre-damage effect.

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