A method for manufacturing a micro abrasive stick with a double-layer structure

Abstract

The application discloses a double-layer micro grinding rod and a preparation method thereof. The micro grinding rod is divided into an external working layer and an internal non-working layer, wherein the external working layer wraps the rod-shaped internal non-working layer; the external working layer is composed of a metal binder A and abrasive grains, and the abrasive grains are selected from diamond grains or CBN grains; and the internal non-working layer is a metal binder B. The micro grinding rod structure can improve the utilization rate of diamond or CBN grains, reduce raw material waste, and reduce production cost. In addition, heat dissipation holes and heat dissipation grooves can be arranged on the grinding rod to reduce the grinding rod processing temperature and prolong the service life. Meanwhile, the FDM double-wire 3D printing technology is adopted to realize the manufacturing of the double-layer micro diamond or CBN grinding rod, fully improve the utilization rate of abrasive grains, improve the production rate, and has industrialization potential, and has a wide application prospect in the material processing field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of abrasive rod preparation, and particularly relates to a preparation method of a micro abrasive rod with a double-layer structure. BACKGROUND

[0002] Diamond or CBN abrasive rods have significant advantages in processing materials with high hardness, brittleness and high precision due to their high hardness, strong wear resistance and good chemical stability. Research shows that when the diamond or CBN abrasive rod is used for opening holes or slots, the wear mainly starts from the edge of the abrasive rod and then gradually spreads to the center. When the number of broken and fallen wear-resistant particles reaches a certain amount, the diameter of the abrasive rod becomes smaller and no longer meets the diameter requirement of the pre-designed hole or slot. Therefore, although the diamond or CBN particles have not been completely lost at this time, the abrasive rod can only be scrapped due to the change in the diameter of the abrasive rod. In addition, irregular falling and breaking of wear-resistant particles occur during the grinding process, so the abrasive rod with a smaller diameter cannot be used for processing holes or slots with smaller diameters.

[0003] In addition, the traditional methods for preparing diamond or CBN abrasive rods include electroplating, brazing and hot-pressing sintering. These methods are not suitable for the manufacture of new abrasive rods due to their own characteristics. The electroplating method has the problems of uneven settlement of wear-resistant particles and high scrap rate, especially when manufacturing new abrasive rods, the working layer is very thin, which is more likely to cause the above problems, resulting in inconsistent exposure of abrasive particles, uneven grinding and poor grinding effect. The brazing method for manufacturing diamond or CBN tools must use suitable brazing filler metal. According to the properties of diamond and CBN, their chemical inertness is extremely high, and a large amount of energy is required for reaction with most metal binders. At present, the number of elements that can chemically react with them and be closely connected is very limited, and these active elements are usually rare and expensive, which will greatly increase the manufacturing cost of new abrasive rods. The hot-pressing sintering method for manufacturing diamond or CBN tools has inherent disadvantages and defects, such as difficulty in mold processing and small-size abrasive rod forming, high energy consumption in the sintering process, poor quality stability of the tool, poor performance, etc. In addition, the diamond or CBN tool is generally placed in the sintering mold as a whole before sintering, and the accurate position of the wear-resistant particles cannot be controlled, so it can only be evenly laid, and therefore it is impossible to manufacture abrasive rods with a double-layer structure. SUMMARY

[0004] In view of the deficiencies of the prior art, the first object of the present application is to provide a micro abrasive rod with a double-layer structure.

[0005] The second object of the present application is to provide a preparation method of a micro abrasive rod with a double-layer structure. The FDM double-wire 3D printing technology can realize efficient production of new abrasive rods, reduce waste of raw materials and save production cost.

[0006] In order to achieve the above objects, the application adopts the following technical solutions:

[0007] The present application provides a double-layer structure micro grinding rod, which is divided into an external working layer and an internal non-working layer, wherein the external working layer wraps the rod-shaped internal non-working layer; the external working layer is composed of metal binder A and abrasive particles selected from diamond particles or CBN particles; and the internal non-working layer is metal binder B.

[0008] The present application provides a novel double-layer structure micro grinding rod, which is divided into an external working layer and an internal non-working layer, and only the external working layer contains wear-resistant particles. This structure can ensure that the wear-resistant particles in the working layer have completely failed before the diameter of the grinding rod starts to change, thereby improving the utilization rate of diamond or CBN particles, reducing raw material waste, and reducing production cost.

[0009] In a preferred embodiment, the diameter of the micro grinding rod is ≤8 mm, the height of the micro grinding rod is 1-30 mm, the thickness of the external working layer is 0.2-1 mm, and the thickness of the external working layer is < the height of the micro grinding rod.

[0010] In a preferred embodiment, the volume fraction of abrasive particles in the external working layer is 5-70%, and the volume fraction of metal binder A is 30-95%.

[0011] In the present application, the volume fraction of abrasive particles can be adjusted according to the application object of the grinding rod to improve the grinding force. However, when the volume fraction of abrasive particles reaches 70%, the grinding effect is sufficient, and higher content only increases the manufacturing cost and reduces the holding force of abrasive particles.

[0012] In a preferred embodiment, the metal binder A in the external working layer is selected from at least one of Cu, Sn, Co, Cr, Ti, Ni, and Mn, or at least one of Cu, Sn, Co, Cr, Ti, Ni, and Mn and WC; and the metal binder B in the internal non-working layer is selected from at least one of Cu, Sn, Co, Cr, Ti, Ni, and Mn, or at least one of Cu, Sn, Co, Cr, Ti, Ni, and Mn and WC.

[0013] Further preferably, the metal binder A and the metal binder B have the same composition.

[0014] In a preferred embodiment, the top end of the micro grinding rod is provided with heat dissipation holes and / or heat dissipation grooves, wherein the diameter of the heat dissipation holes is 0.1-7 mm, the depth is 0.1-25 mm, the width of the heat dissipation grooves is 0.1-7 mm, and the depth is 0.1-25 mm.

[0015] The heat dissipation holes or heat dissipation grooves are arranged on the end face of the grinding rod, so that cooling liquid continuously flows through the end face of the grinding rod during operation, thereby reducing the temperature of the grinding rod and prolonging the service life of the diamond or CBN grinding rod.

[0016] The application also provides a preparation method of the micro abrasive rod with a double-layer structure. The pre-alloy powder C, abrasive grains and additives are mixed to obtain an external working layer mixture, the external working layer mixture is mixed and granulated to obtain external working layer granules, and the external working layer granules are drawn into external working layer filaments. The pre-alloy powder D and additives are mixed to obtain an internal non-working layer mixture, the internal non-working layer mixture is mixed and granulated to obtain internal non-working layer granules, and the internal non-working layer granules are drawn into internal non-working layer filaments. The external working layer filaments and the internal non-working layer filaments are respectively placed in the corresponding double feed ports of the FDM double-filament 3D printing equipment, and are synchronously printed to obtain a micro abrasive rod green body. The micro abrasive rod green body is degreased to obtain a degreased body, and the degreased body is sintered to obtain the micro abrasive rod with a double-layer structure.

[0017] In actual operation, the powder raw materials of the external working layer and the internal non-working layer are respectively placed in the planetary ball mill for pretreatment.

[0018] Preferably, the particle size of the abrasive grains is ≤800 μm, preferably 100-300 μm, the particle size of the pre-alloy powder C is ≤80 μm, preferably 30-50 μm, and the particle size of the pre-alloy powder D is ≤80 μm, preferably 30-50 μm.

[0019] The inventors find that the particle size of the abrasive grains and the pre-alloy powder is controlled within the above range, which can ensure the printing precision and the performance of the finished product. If the particle size of the raw material is too large, the printing precision will be reduced, and if the particle size of the raw material is too small, the grinding effect will be reduced and the cost of the raw material will be increased. In actual operation, the pre-alloy powder C is obtained by mixing the corresponding raw material powder according to the designed component proportion of the metal binder A, and the pre-alloy powder D is obtained by mixing the corresponding raw material powder according to the designed component proportion of the metal binder B.

[0020] Preferably, the volume fraction of the additive in the external working layer mixture and the internal non-working layer mixture is 30-70%.

[0021] Preferably, the additive in the external working layer mixture and the internal non-working layer mixture is composed of the following components in terms of mass percentage: paraffin (PW) 40-60%, edible oil (EO) 0.5-4%, ethylene-vinyl acetate copolymer (EVA) 22-48%, high-density polyethylene (HDPE) 10-20%, dioctyl phthalate (DOP) 0.5-4%, and stearic acid (SA) 0.5-2%.

[0022] In the present application, the same additive is used for the inner and outer layers, which can ensure the consistency of subsequent sintering, improve the quality of the composite material, and the provided additive can be suitable for both diamond and CBN abrasive particles and pre-alloy powder, and the prepared wire has good flexibility, flowability and uniformity, so that the prepared wire can be smoothly extruded and the green body with uniform performance can be printed.

[0023] In a preferred embodiment, the particle size of the outer working layer granules and the inner non-working layer granules is 0.5-5 mm. In this range, the granules can be prepared into wire with excellent performance and not easy to break. If the particle size is too large, the screw of the wire drawing machine may be damaged, and if the particle size is too small, the wire is too thin and is prone to breakage.

[0024] In a preferred embodiment, the diameter of the outer working layer granules and the inner non-working layer granules is 1.6-2.1 mm, preferably 1.75 mm.

[0025] The inventor found that controlling the diameter of the wire within the above range can obtain the best performance of the abrasive rod.

[0026] In actual operation, a double-layer micro abrasive rod is established in a computer three-dimensional modeling software, the model file is stored in STL format, and the file is cut by using slicing software to make each slice layer have processability, and the final slice file is imported into an FDM double-wire 3D printing equipment; then the two kinds of wire are respectively put into the feeding port of the printer, the working parameters of the double-wire 3D printer are set, the equipment is started, and the micro abrasive rod green body is printed.

[0027] In a preferred embodiment, the printing parameters are as follows: nozzle diameter 0.1-1 mm, printing layer height 0.04-0.4 mm, extrusion rate 5-200 mm / s, and extrusion ratio 80-200%.

[0028] In a preferred embodiment, the micro abrasive rod green body is first placed in an organic solvent for solvent debinding, and then subjected to thermal debinding.

[0029] Further preferably, the solvent for solvent debinding is selected from at least one of kerosene, gasoline, benzene, ketone, chlorinated alkane, and olefin.

[0030] Further preferably, the thermal debinding process comprises the following steps: heating from room temperature to 150-250℃ at a heating rate of 3-5℃ / min, and holding for 45-75 min; then heating to 380-420℃ at a heating rate of 3-5℃ / min, and holding for 100-150 min; and then heating to 450-550℃ at a heating rate of 2-4℃ / min, and holding for 60-120 min.

[0031] In the heat debinding process of the present application, based on the difference in the pyrolysis temperature range of different components of the binder, step-by-step debinding is carried out in a gradient heating mode, which can effectively ensure the integrity of the green body and the removal effect of the binder in the green body, and avoid the generation of debinding defects.

[0032] Preferably, the sintering is hot-press sintering, the pressure of the hot-press sintering is 2.0-5.0 MPa, the temperature of the hot-press sintering is 700-1000 DEG C, and the time of the hot-press sintering is 60-500 s.

[0033] Beneficial effects

[0034] The present application provides a double-layer structure micro grinding rod, which sets a non-working layer without wear-resistant particles in the external working layer, reduces the internal raw material waste, and saves the production cost; according to the need, the heat dissipation holes and heat dissipation grooves can also be arranged at the top of the grinding rod, so that the cooling liquid continuously flows through the end surface of the grinding rod during the working of the grinding rod, the temperature of the grinding rod is reduced, and the service life of the micro grinding rod is prolonged.

[0035] The present application adopts FDM double-wire printing technology to prepare a double-layer structure micro grinding rod, and the FDM double-wire printing technology has the following advantages: (1) precise manufacturing of complex shape and micro structure can be realized; (2) the wear-resistant particles in the working layer can be avoided from being damaged; (3) the raw material preparation is simple, the instrument price is low, and the industrialization potential is possessed; (4) the forming speed is fast, the manufacturing efficiency is high, and multi-component mixed printing can be realized; (5) the exposed height of the abrasive particles is consistent, and the grinding performance is excellent. Therefore, the present application adopts FDM double-wire 3D printing technology, so that several low-cost FDM printing devices can work simultaneously, the industrialized production of the new type of diamond or CBN grinding rod can be realized, the production efficiency is greatly improved; and the size and component composition of the inner and outer layers and the heat dissipation holes and heat dissipation grooves can be adjusted according to the actual production, so that the personalized production of the new type of diamond or CBN grinding rod can be completed. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a schematic diagram of a double-layer structure micro grinding rod, wherein 1 is a heat dissipation hole; and 2 is a heat dissipation groove.

[0037] Figure 2 is a cross-sectional view of a double-layer structure micro grinding rod, wherein 3 is a working layer; and 4 is a non-working layer. DETAILED DESCRIPTION

[0038] As shown in Figure 1 , 2 , the double-layer structure micro grinding rod comprises a working layer, a non-working layer, and heat dissipation holes and heat dissipation grooves.

[0039] Example 1:

[0040] The designed micro diamond grinding rod has a diameter x height size of 4 mm x 10 mm, a working layer thickness of 1 mm, a diamond volume fraction of 10%, a metal binder volume fraction of 90%, the metal binder is selected from a Cu-Sn alloy, the mass fraction of Cu is 90%, the mass fraction of Sn is 10%, the non-working layer uses the same metal powder (without diamond), the diameter of the heat dissipation hole is 0.5 mm, the depth is 1 mm, the width of the heat dissipation groove is 0.5 mm, and the depth is 1 mm. The pre-alloy powder has a particle size of 38-44 μm, and the diamond powder has a particle size of 120-150 μm.

[0041] The manufacturing process flow is as follows:

[0042] (1) Select an appropriate amount of diamond micro powder and Cu-Sn pre-alloy powder according to the designed component ratio to form the working layer raw material, and take an appropriate amount of Cu-Sn pre-alloy powder as the non-working layer raw material, and then put them into the planetary ball mill for pretreatment;

[0043] (2) Put the two kinds of powder raw materials after pretreatment into the internal mixer after adding an additive with a volume fraction of 45%, and mix them uniformly, the additive composition is 50% of PW, 2% of EO, 30% of EVA, 15% of HDPE, 2% of DOP and 1% of SA;

[0044] (3) Granulate the two kinds of mixed materials through the granulator to obtain granular materials with an average particle size of 3 mm;

[0045] (4) Put the two kinds of granular materials into the wire drawing machine to manufacture Cu-Sn (working layer) wire containing diamond and pure Cu-Sn (non-working layer) wire, and the wire diameter is 1.75 mm;

[0046] (5) Establish a diamond grinding rod model of this size in a computer three-dimensional modeling software, store the model file in STL format, and then cut the file directly using a slicing software to make each slice layer thickness have processability, and import the final slicing file into an FDM double-silk 3D printing equipment;

[0047] (6) Put the two kinds of wire into the feeding port of the printer, use a nozzle with a diameter of 0.4 mm, set the working parameters of the double-silk 3D printer, wherein the printing layer height is 0.15 mm, the extrusion rate is 15 mm / s, and the extrusion ratio is 100%, start the equipment, and print the new diamond grinding rod green body;

[0048] (7) the printing green body is immersed in kerosene for a period of time, and then heat debinding is performed after dissolving part of the additive, the temperature is increased to 200°C from room temperature at a rate of 5°C / min, and then the temperature is increased to 400°C at a rate of 5°C / min, and then the temperature is increased to 500°C at a rate of 3°C / min, and then the temperature is kept for 90 min;

[0049] (8) the debound grinding rod is placed into a sintering furnace, the pressure is increased to 3 MPa, the temperature is increased to 800°C, and the pressure and temperature are kept for 300 s, then the heating is stopped, the pressure is decreased, the temperature of the equipment is increased to room temperature, and then the pressure is decreased to standard atmospheric pressure, and then the grinding rod is taken out from the sintering furnace, and then the new diamond grinding rod is obtained.

[0050] Processing object: hard alloy;

[0051] Processing effect: after processing 10 pieces of the commercially available diamond grinding rod with the same specification, the hard alloy has a collapse edge of more than 0.15 mm, and is unqualified; after processing 21 pieces of the double-layer structure diamond grinding rod of Example 1, the hard alloy has a good appearance, and the processing life is 25 pieces.

[0052] Example 2:

[0053] The diameter x height size of the designed micro CBN grinding rod is 5 mm x 8 mm, the working layer thickness is 0.6 mm, the volume fraction of CBN is 20%, the volume fraction of metal binder is 80%, the metal binder is selected from Ni-Cr alloy, the mass fraction of Ni is 60%, and the mass fraction of Cr is 40%, the non-working layer uses the same metal powder (without CBN), the diameter of the heat dissipation hole is 0.8 mm, the depth is 1.5 mm, the width of the heat dissipation groove is 0.8 mm, and the depth is 1 mm. The pre-alloy powder particle size is 38-44 μm, and the CBN powder particle size is 120-150 μm.

[0054] The manufacturing process flow is as follows:

[0055] (1) the appropriate amount of CBN micro powder and Ni-Cr pre-alloy powder is selected according to the designed component ratio to form the working layer raw material, and the appropriate amount of Ni-Cr pre-alloy powder is selected as the non-working layer raw material, and then the two kinds of raw materials are respectively put into the planetary ball mill for pretreatment;

[0056] (2) the two kinds of raw materials after pretreatment are respectively added into the mixer after adding the additive with a volume fraction of 50%, and then the additive is mixed uniformly in the mixer, the additive composition is 55% of PW, 2% of EO, 28% of EVA, 12% of HDPE, 2% of DOP and 1% of SA;

[0057] (3) the two kinds of mixed materials are respectively granulated through the granulator, and then the granular material with an average particle size of 3.5 mm is obtained;

[0058] (4) Put the two kinds of granular materials into the wire drawing machine respectively to manufacture the CBN-containing Ni-Cr (working layer) wire and the pure Ni-Cr (non-working layer) wire, and the diameter of the wire is 1.80 mm;

[0059] (5) A CBN grinding rod model of the size is established in a computer three-dimensional modeling software, the model file is stored in STL format, and the file is directly cut by using a slicing software so that each slice layer has machinability, and the final slice file is imported into an FDM double-wire 3D printing equipment;

[0060] (6) Put the two kinds of wires into the feeding port of the printer respectively, use a nozzle with a diameter of 0.3 mm, set the working parameters of the double-wire 3D printer, wherein the printing layer height is 0.2 mm, the extrusion rate is 20 mm / s, and the extrusion ratio is 110%, start the equipment, and print the new CBN grinding rod green body;

[0061] (7) Soak the printed green body in kerosene for a period of time, dissolve part of the additives, and then perform heat debinding, heat from room temperature to 200℃ at a heating rate of 5℃ / min, keep for 60 min, then heat from 200℃ to 400℃ at a heating rate of 5℃ / min, keep for 120 min, and finally heat from 400℃ to 500℃ at a heating rate of 3℃ / min, keep for 90 min;

[0062] (8) Put the debound grinding rod into a sintering furnace, increase the pressure to 3 MPa, heat to 950℃, and keep the pressure and temperature for 500 s, then stop heating, reduce the pressure, make the temperature of the equipment reach room temperature, and after the pressure is reduced to standard atmospheric pressure, take out the grinding rod from the sintering furnace, and the new CBN grinding rod is obtained.

[0063] Processing object: hard alloy;

[0064] Processing effect: after processing 8 pieces of the commercially available CBN grinding rod of the same specification, the hard alloy has a collapse edge of more than 0.15 mm, which is unqualified; after processing 17 pieces of the CBN grinding rod of Example 2, the hard alloy has a good appearance, and the processing life is 19 pieces.

[0065] Comparative example:

[0066] In the comparative example, only one experimental parameter is changed, and other experimental conditions are the same as those in Example 1, and the comparative results are shown in Table 1.

[0067] Table 1 Comparative experimental results

[0068]

Claims

1. A method of making a microfiche abrasive stick of a double layer construction, characterized by: According to the designed component proportion of the metal binder A, the corresponding raw material powders are mixed to obtain a pre-alloy powder C, the pre-alloy powder C, abrasive grains and additives are mixed to obtain an external working layer mixture, the external working layer mixture is mixed and granulated to obtain an external working layer granular material, the external working layer granular material is drawn to obtain an external working layer filament material, according to the designed component proportion of the metal binder B, the corresponding raw material powders are mixed to obtain a pre-alloy powder D, the pre-alloy powder D and additives are mixed to obtain an internal non-working layer mixture, the internal non-working layer mixture is mixed and granulated to obtain an internal non-working layer granular material, the internal non-working layer granular material is drawn to obtain an internal non-working layer filament material, the external working layer filament material and the internal non-working layer filament material are respectively placed in the corresponding double feeding ports of the FDM double-silicon 3D printing equipment, and are synchronously printed to obtain a micro abrasive rod green body, the micro abrasive rod green body is degreased to obtain a degreased body, and the degreased body is sintered to obtain a micro abrasive rod with a double-layer structure. The additives in the external working layer mixture and the internal non-working layer mixture each have the following composition by mass percentage: PW 40-60%, EO 0.5-4%, EVA 22-48%, HDPE 10-20%, DOP 0.5-4%, and SA 0.5-2%. The micro abrasive rod green body is first placed in an organic solvent for solvent degreasing, and then is subjected to thermal degreasing. The thermal degreasing process is as follows: first, the temperature is raised from room temperature to 150-250 DEG C at a rate of 3-5 DEG C / min, and is kept at this temperature for 45-75 min; then, the temperature is raised to 380-420 DEG C at a rate of 3-5 DEG C / min, and is kept at this temperature for 100-150 min; and then, the temperature is raised to 450-550 DEG C at a rate of 2-4 DEG C / min, and is kept at this temperature for 60-120 min. The micro abrasive rod is divided into an external working layer and an internal non-working layer, and the external working layer wraps the rod-shaped internal non-working layer; the external working layer is composed of a metal binder A and abrasive grains, and the abrasive grains are selected from diamond particles or CBN particles; and the internal non-working layer is a metal binder B. The metal binder A in the external working layer is selected from at least one of Cu, Sn, Co, Cr, Ti, Ni and Mn, or at least one of Cu, Sn, Co, Cr, Ti, Ni and Mn and WC; and the metal binder B in the internal non-working layer is selected from at least one of Cu, Sn, Co, Cr, Ti, Ni and Mn, or at least one of Cu, Sn, Co, Cr, Ti, Ni and Mn and WC. The component composition of the metal binder A is consistent with that of the metal binder B.

2. The method for preparing a micro-grinding rod with a double-layer structure according to claim 1, characterized in that: The particle size of the abrasive grains is ≤800 μm, the particle size of the pre-alloy powder C is ≤80 μm, and the particle size of the pre-alloy powder D is ≤80 μm. The volume fraction of the additives in the external working layer mixture and the internal non-working layer mixture is 30-70%.

3. The method for preparing a micro-grinding rod with a double-layer structure according to claim 1, characterized in that: The particle size of the external working layer granular material and the internal non-working layer granular material is 0.5-5 mm, and the diameter of the external working layer filament material and the internal non-working layer filament material is 1.6-2.1 mm.

4. The method of claim 1, wherein the micro abrasive stick of double-layer structure is prepared by the following steps: (1) preparing a double-layer structure of the micro abrasive stick; (2) coating the double-layer structure with a protective layer; and (3) polishing the protective layer. The parameters of the printing are as follows: nozzle diameter 0.1-1 mm, printing layer height 0.04-0.4 mm, extrusion rate 5-200 mm / s, and extrusion ratio 80-200%.

5. The method for preparing a micro-grinding rod with a double-layer structure according to claim 1, characterized in that: The micro grinding rod green body is first placed in an organic solvent for solvent degreasing, and then is subjected to heat degreasing; The organic solvent for solvent degreasing is at least one selected from kerosene, gasoline, benzene, ketone, chlorinated alkane and olefin; The heat degreasing process is as follows: first, the temperature is raised from room temperature to 150-250 DEG C at a rate of 3-5 DEG C / min, and then is kept for 45-75 min; then, the temperature is raised to 380-420 DEG C at a rate of 3-5 DEG C / min, and then is kept for 100-150 min; then, the temperature is raised to 450-550 DEG C at a rate of 2-4 DEG C / min, and then is kept for 60-120 min.

6. The method of claim 1, wherein the micro abrasive stick of double-layer structure is prepared by the following steps: (1) preparing a double-layer structure of the micro abrasive stick; (2) coating the double-layer structure with a protective layer; and (3) polishing the protective layer. The sintering is hot-press sintering, the pressure of the hot-press sintering is 2.0-5.0 MPa, the temperature of the hot-press sintering is 700-1000 DEG C, and the time of the hot-press sintering is 60-500 s.

7. The method for preparing a micro-grinding rod with a double-layer structure according to claim 1, characterized in that: The diameter of the micro grinding rod is ≤8 mm, the height of the micro grinding rod is 1-30 mm, the thickness of the outer working layer is 0.2-1 mm, and the thickness of the outer working layer is < the height of the micro grinding rod.

8. The method for preparing a micro-grinding rod with a double-layer structure according to claim 1, characterized in that: In the outer working layer, the volume fraction of the abrasive particles is 5-70%, and the volume fraction of the metal bond A is 30-95%.

9. The method for preparing a micro-grinding rod with a double-layer structure according to claim 1, characterized in that: The top end of the micro grinding rod is provided with heat dissipation holes and / or heat dissipation grooves, wherein the diameter of the heat dissipation holes is 0.1-7 mm, the depth is 0.1-25 mm, the width of the heat dissipation grooves is 0.1-7 mm, and the depth is 0.1-25 mm.

Images