A method for the adhesive jet 3D printing forming of a porous diamond grinding wheel and the porous diamond grinding wheel obtained

Abstract

The application discloses a kind of binder jetting 3D printing forming methods of porous diamond grinding wheel and obtained porous diamond grinding wheel, comprising: design the frame structure of diamond grinding wheel;Binder jetting forming frame structure green body: mixed diamond abrasive and filler, obtain mixed powder;Mixed powder is filled into frame structure green body, and is vibrated;The green body filled with powder is placed in atmosphere furnace and is pre-sintered;After pre-sintering, brown piece is placed in vacuum furnace and is bronze infiltrated treatment;Impurities attached to the surface of the grinding wheel are removed, and the grinding wheel is trimmed to expose the diamond abrasive.The forming method of the present application can customize the geometry and internal porosity of the grinding wheel without consuming a large amount of computing power.The parts prepared by binder jetting additive manufacturing combined with infiltration forming can control the process parameters to control the organization, pore size and pore distribution of the grinding wheel, and the prepared grinding wheel has stronger pertinence.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of grinding and 3D printing, and more particularly relates to a binder jetting 3D printing forming method of a porous diamond grinding wheel and a porous diamond grinding wheel obtained. BACKGROUND

[0002] The existing grinding wheels on the market are usually obtained by mixing abrasive powder and binder powder in a certain proportion, then pressing into a mold for molding, and then through high-temperature sintering treatment to obtain the final product. Metal binder diamond grinding wheels have the advantages of strong abrasive holding force, good bonding strength, good wear resistance, long service life and the ability to withstand large grinding force, and therefore have broad application prospects and are one of the choices for realizing high-speed precision grinding.

[0003] The traditional metal binder grinding wheel is limited by the forming process, and the internal porosity and pore size are very small, which leads to poor self-sharpening of the grinding wheel, and in addition, the chip space is limited, and the surface is easy to accumulate debris, which further reduces the cooling performance of the grinding wheel, thus easily causing the workpiece surface to be burned, and it is difficult to obtain excellent processing quality.

[0004] In recent years, with the development of additive manufacturing technology, an additive manufacturing technology for forming a porous grinding wheel has appeared, and mainly uses laser selective melting technology. With the unique advantages of additive manufacturing, it is possible to prepare a grinding wheel with an internal porous structure, so that the disadvantages of low porosity and small chip space can be overcome to some extent. However, there are still some problems to be solved in the laser selective melting forming of porous metal binder diamond grinding wheels, such as the need for three-dimensional modeling to generate various sizes of pores in the grinding wheel, especially when the grinding wheel structure is complex, a large amount of computing power is consumed; in addition, the use of laser selective melting forming has special requirements for the selection of metal binders, such as when the melting point of the metal binder is high, high-energy laser will cause the diamond to be severely carbonized, affecting its physical properties, and when some materials with high reflectivity are used, the laser energy absorption efficiency will be affected, and thus the forming performance of the part will be affected. SUMMARY

[0005] In view of the improvement needs of the prior art, the present application provides a forming method of a porous metal-based binder diamond grinding wheel segment based on binder jetting additive manufacturing and a porous diamond grinding wheel obtained. The present application can realize the random generation and on-demand generation of internal pores of the metal-based binder diamond grinding wheel without consuming a large amount of computing power, improve the chip removal and heat dissipation problems of the grinding wheel during processing, and at the same time expand the selection range of the metal binder, realizing the customized forming of the grinding wheel for the processing target.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] In a first aspect, the present application provides a binder jet 3D printing forming method of a porous diamond grinding wheel, comprising:

[0008] Step 1, designing a framework structure of the diamond grinding wheel;

[0009] Step 2, binder jet forming a framework structure green body;

[0010] Step 3, mixing diamond abrasive and filler to obtain a mixed powder;

[0011] Step 4, filling the mixed powder into the framework structure green body, and then placing the green body filled with powder on a vibration platform to vibrate;

[0012] Step 5, placing the green body filled with powder into an atmosphere furnace for pre-sintering;

[0013] Step 6, placing the brown part after pre-sintering into a vacuum furnace for bronze infiltration treatment;

[0014] Step 7, removing impurities attached to the surface of the grinding wheel, and then finishing the grinding wheel to expose the diamond abrasive.

[0015] As a further technical solution, the framework structure in step 1 includes a porous structure framework, and a skin layer is covered on the periphery of the porous structure framework, and a powder filling port is reserved on the skin layer.

[0016] As a further technical solution, in step 2, the metal powder material used for printing the framework structure is selected according to the required structural strength of the grinding wheel and the processing object, and the framework structure green body is formed by using the binder jet additive manufacturing method.

[0017] As a further technical solution, in step 3, the diamond abrasive and the filler are weighed according to the required weight ratio, and are placed in a mixing container; different sizes of stainless steel grinding balls are added to the mixed powder according to the weight ratio of 1:1, and the mixing is carried out in a three-dimensional powder mixer until the mixing is uniform and there is no obvious composition segregation.

[0018] As a further technical solution, in step 4, the vibration time and power are controlled to control the vibration of the mixed powder.

[0019] As a further technical solution, in step 5, the pre-sintering temperature is much lower than the melting point of the metal.

[0020] As a further technical solution, in step 7, if there is a skin structure on the working surface of the grinding wheel, it is removed together during the grinding wheel finishing.

[0021] As a further technical solution, according to GB / T6409.1-1994, the abrasive tool concentration value of the abrasive wheel segment is defined as 100% when the abrasive wheel segment contains 0.88 grams of diamond abrasive per cubic centimeter of volume. According to the structural design parameters of the abrasive wheel segment and the abrasive tool concentration design requirements of the abrasive wheel, the dosage calculation formula of the diamond abrasive, the filler and the bronze is as follows:

[0022] M 金刚石 =C 砂轮 ×V 砂轮 / 1cm 3 ×0.88g

[0023] M 填料 =D1×ρ 填料 ×(V 砂轮 ×P 框架 -M 金刚石 / (D1×ρ 金刚石 ))

[0024] M 青铜 =ρ 青铜 ×(V 砂轮 ×P 框架 ×(1-D1)+V 砂轮 ×(1-P 框架 )×(1-D2))

[0025] Wherein, M 金刚石 is the dosage of diamond powder, M 填料 is the dosage of filler required, M 青铜 is the amount of bronze required for infiltration, ρ 填料 is the density of the filler material, ρ 金刚石 is the density of diamond, ρ 青铜 is the density of bronze, C 砂轮 is the abrasive tool concentration of the abrasive wheel set, V 砂轮 is the volume of the abrasive wheel, P 框架 is the porosity of the binder jetting formed frame structure, excluding the internal porosity of the printed part, D1 is the bulk density of the mixed powder of diamond and filler, and D2 is the relative density of the binder jet printed frame part.

[0026] In the second aspect, the application discloses a porous diamond abrasive wheel obtained by the binder jet 3D printing forming method.

[0027] Overall, compared with the prior art, the above technical solutions conceived by the application can achieve the following beneficial effects:

[0028] 1、The porous diamond grinding wheel forming method of the present application is based on binder jet additive manufacturing, which is congenitally suitable for forming porous materials, and by controlling the sintering temperature and time, the pores can be naturally formed in the part. Therefore, using this technology can realize the customization of the geometric shape and internal pores of the grinding wheel without consuming a large amount of computer power. When larger pores are needed in the grinding wheel, the design of the frame structure can be adjusted to add the designed pores as needed, so only the designed pores need to consume part of the computer power. In addition, the parts prepared by applying binder jet additive manufacturing combined with infiltration forming can realize the regulation of the organization, pore size and pore distribution of the grinding wheel by adjusting the process parameters, and the prepared grinding wheel has stronger pertinence.

[0029] 2、The porous diamond grinding wheel filler in the process method of the present application can be selected as needed, and the holding force of the abrasive can be controlled by cooperating with the corresponding forming process parameters, and further functional properties of special materials can be provided. The adjustment of the mechanical strength of the grinding wheel can be realized by controlling the sintering process and bronze infiltration process of the filler.

[0030] 3、The pre-sintering and infiltration temperature in the process method of the present application is much lower than the laser additive manufacturing molten pool temperature, so the thermal damage to the diamond abrasive is smaller. The final grinding wheel adopts the method of infiltration to obtain mechanical strength, and the selection of metal binder is much less limited than laser additive manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0031] The present application will be further described below in conjunction with the drawings:

[0032] Figure 1 It is a process schematic diagram of the binder jet forming porous diamond grinding wheel of the present application.

[0033] Figure 2 It is a structural design diagram of the binder jet forming porous diamond grinding wheel of the present application.

[0034] Among them, specifically: 1, skin, 2, porous structure frame.

[0035] Figure 3 It is an electron microscope diagram of the polished surface of the binder jet forming porous diamond grinding wheel of the present application. DETAILED DESCRIPTION

[0036] It should be pointed out that the following detailed description is exemplary and is intended to provide further description of the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0037] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0038] As introduced in the background, in order to solve the above technical problems, the present application proposes a binder jet 3D printing forming method of porous diamond grinding wheel, comprising:

[0039] Step 1, design the framework structure: according to the required porosity, pore size, pore distribution, structural strength and geometric shape of the grinding wheel, design the internal interconnected porous structure framework 2. Cover a very thin skin 1 on the periphery of the porous structure framework 2, and keep the powder filling port in one direction. The function of the skin 1 is to ensure that the powder can fully fill the porous structure without flowing out when filling the powder into the framework structure. If the working surface of the grinding wheel has a skin structure, it can be removed during grinding wheel dressing.

[0040] Step 2, binder jet forming framework structure green body: according to the required structural strength of the grinding wheel and the processing object, select the metal powder material used for printing the framework structure, and use the binder jet additive manufacturing method to form the framework structure green body. Taking advantage of the advantages of binder jet additive manufacturing in forming porous materials, the framework structure itself can be made porous, which is more conducive to subsequent infiltration treatment.

[0041] Step 3, mix the powder raw material: the powder raw material is divided into diamond abrasive and filler. Weigh the diamond abrasive and filler according to the required weight ratio and put them into the mixing container. Diamond abrasive is mainly used for removing material; filler is used to hold diamond particles and provide overall mechanical properties of the grinding wheel.

[0042] Add stainless steel grinding balls of different sizes in a weight ratio of 1:1 to the mixed powder, and mix in a three-dimensional powder mixer until the mixture is uniform and there is no obvious composition segregation.

[0043] Step 4, fill the framework structure: fill the mixed powder into the framework structure green body, and then put the filled powder green body on the vibration platform and shake it. Control the vibration time and power to prevent powder composition segregation.

[0044] Step 5, pre-sintering: the green body filled with powder is put into an atmosphere furnace for two-stage pre-sintering, which aims to remove the binder in the green body while making the green body obtain a certain mechanical strength to ensure that the printed structure will not be damaged during infiltration. The pre-sintering temperature can be much lower than the melting point of the metal, so the high-temperature carbonization of the diamond particles can be reduced as much as possible, which is beneficial to maintaining the mechanical properties of the diamond particles.

[0045] Step 6, infiltration: the brown part after pre-sintering is put into a vacuum furnace for bronze infiltration treatment. The temperature used for bronze infiltration is lower, which can reduce the degree of high-temperature carbonization of diamond particles as much as possible. At the same time, bronze is the most commonly used metal binder for diamond tools, which can make the grinding wheel obtain sufficient mechanical strength and stronger diamond holding force.

[0046] Step 7, post-processing: remove the impurities attached to the surface of the grinding wheel, and then perform grinding wheel finishing to expose the diamond abrasive.

[0047] The above porous diamond grinding wheel forming method does not need to consume a large amount of computing power to realize the customization of the geometric shape and internal pores of the grinding wheel. The pores are divided into designed pores and naturally generated pores during the forming process. Only the designed pores need to consume computer computing power. In addition, the parts formed by combining binder jet additive manufacturing with infiltration can realize the regulation of grinding wheel organization, pore size, and pore distribution by adjusting process parameters, and the prepared grinding wheel has stronger pertinence.

[0048] Further, according to GB / T6409.1-1994, the abrasive concentration value of the grinding wheel segment is defined as 100% when containing 0.88 grams of diamond abrasive per cubic centimeter of volume. According to the structural design parameters of the grinding wheel segment and the abrasive concentration design requirements of the grinding wheel, the dosage calculation formula of diamond, filler and bronze is as follows:

[0049] M 金刚石 =C 砂轮 ×V 砂轮 / 1cm 3 ×0.88g

[0050] M 填料 =D1×ρ 填料 ×(V 砂轮 ×P 框架 -M 金刚石 / (D1×ρ 金刚石 ))

[0051] M 青铜 =ρ 青铜 ×(V 砂轮 ×P 框架 ×(1-D1)+V 砂轮 ×(1-P 框架 )×(1-D2))

[0052] wherein, M 金刚石 is the amount of diamond powder, M 填料 is the amount of filler required, M 青铜 is the amount of bronze required for infiltration, p 填料 is the density of the filler material, p 金刚石 is the density of the diamond, p 青铜 is the density of the bronze, C 砂轮 is the abrasive concentration of the designed grinding wheel, V 砂轮 is the volume of the grinding wheel, P 框架 is the porosity of the binder jetting formed framework structure, the internal porosity excluding the printed part, D1 is the bulk density of the mixed powder of diamond, filler, D2 is the relative density of the binder jetting printed framework part.

[0053] The porous diamond grinding wheel filler of the present application can be selected as needed, matched with corresponding forming process parameters, the holding force of the abrasive is controllable, and the functionality of special materials can be further provided. The adjustment of the mechanical strength of the grinding wheel can be realized by controlling the sintering process of the filler and the bronze infiltration process.

[0054] The following will be described in conjunction with specific examples:

[0055] Example 1

[0056] The binder jetting 3D printing forming method of the porous diamond grinding wheel disclosed in this embodiment is as follows:

[0057] Step 1, as shown in Figure 2 , a framework structure is designed; the porous diamond grinding wheel designed in this embodiment is a cylindrical framework structure, the inside of the cylindrical framework structure is a connected lattice structure, the porosity is 90%, and a layer of skin is arranged on the outside, an opening is formed on the surface of the skin for filling diamond and filler powder, and the thickness of the skin is 0.5 mm.

[0058] Step 2, binder jetting forming framework structure green body, spherical 316L stainless steel powder prepared by gas atomization technology is selected as the material for printing the framework structure, the powder size is 20 μm; the binder jetting additive manufacturing method is used to form the framework structure green body. The advantage of binder jetting additive manufacturing in forming porous materials can realize the porosity of the framework structure itself, which is more conducive to the subsequent infiltration treatment.

[0059] Step 3, mixing the powder raw materials, in this embodiment, the powder raw materials are divided into diamond powder, stainless steel powder and stainless steel ball; wherein the diamond powder size is 30 μm, the filler selected is 316L stainless steel powder with a size of 20-50 μm, mixed in a weight ratio of 4:9, and then added with 304 stainless steel balls with a weight equal to that of the mixed powder, the stainless steel balls have a diameter of 4 mm and 8 mm. The three-dimensional powder mixing machine is set at a parameter of 50 RPM, and each direction is run for one hour.

[0060] Step 4, filling the frame structure; the mixed powder is filled into the printed cylindrical frame structure, and the cylindrical part is placed on the self-made ultrasonic vibration table and vibrated for 5 s. The ultrasonic generator parameter is 40 kHz, and the power is 50 w.

[0061] Step 5, the part is placed into a tube furnace, heated to 500℃ at a heating rate of 2℃ / min in an argon atmosphere, and kept for 1 hour to remove the binder in the part; then heated to 900℃ at a heating rate of 2℃ / min, and kept for 1 hour to complete the pre-sintering.

[0062] Step 6, bronze powder is laid on the bottom of the crucible, and the pre-sintered part is placed on the bronze powder. The crucible is placed into a tube furnace, heated to 1100℃ at a heating rate of 5℃ / min in a vacuum environment, and kept for one hour to complete the infiltration. Figure 3 is the SEM image of the polished surface of the formed part, the light-colored part is the sintered matrix, and the black irregular particles are diamond particles. After polishing with silicon carbide sandpaper, the diamond particles still exist, indicating that the holding force of the grinding wheel on the diamond abrasive particles is high.

[0063] Step 7, after the infiltration is completed, the part is taken out, the surface-attached impurities are removed, and the grinding wheel working surface is trimmed using a general-purpose grinding wheel trimming device.

[0064] Example 2

[0065] The embodiment discloses a binder jetting 3D printing forming method of a porous diamond grinding wheel, as follows:

[0066] Step 1, as shown in Figure 2 , a frame structure is designed, the porous diamond grinding wheel designed in this embodiment is a cylindrical frame structure, wherein the inside of the cylindrical frame structure is a connected lattice structure, and the porosity is 90%. A skin is arranged on the outside, and an opening is formed on the surface of the skin for filling diamond and filler powder, and the skin has a thickness of 0.5 mm.

[0067] Step 2, binder jetting forming the green body of the frame structure, spherical 316L stainless steel powder prepared by gas atomization technology is selected as the material for printing the frame structure, and the powder size is 20 μm.

[0068] Step 3, mixing the powder raw materials, the powder raw materials in this embodiment are diamond powder, stainless steel powder and pure nickel powder; the diamond powder size is 30 μm, the filler selected is 316L stainless steel powder with size of 20-50 μm and pure nickel powder with size of 10-20 μm, mixed according to the weight ratio of diamond and filler 4:9, then add 304 stainless steel balls with weight equal to the mixed powder, the stainless steel balls have diameter of 4 mm and 8 mm. The three-dimensional powder mixing machine sets the parameters as 50 RPM, each running for one hour in the positive and reverse directions.

[0069] Step 4, filling the mixed powder into the printed cylindrical frame structure, placing the cylindrical part on the self-made ultrasonic vibration table, and vibrating for 5 s. The ultrasonic generator parameters are 40 kHz and power 50 w.

[0070] Step 5, placing the part into a tube furnace, heating to 500 ℃ at a heating rate of 2 ℃ / min in an argon atmosphere, keeping for 1 hour to remove the binder in the part, then heating to 900 ℃ at a heating rate of 2 ℃ / min, keeping for 1 hour to complete the pre-sintering.

[0071] Step 6, spreading bronze powder on the bottom of the crucible, and placing the pre-sintered part on the bronze powder. Placing the crucible into a tube furnace, heating to 1100 ℃ at a heating rate of 5 ℃ / min in a vacuum environment, keeping for one hour to complete the infiltration. The Fe-based filler cooperates with Ni and Cu, which can further reduce the sintering temperature, reduce the thermal erosion of the binder metal to the diamond, and improve the holding force of the diamond.

[0072] Step 7, after the infiltration is completed, taking out the part, removing the impurities attached to the surface, and using a general grinding wheel dressing device to dress the working surface of the grinding wheel.

[0073] Finally, it should be noted that the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations.

[0074] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A binder jet 3D printing forming method of a porous diamond grinding wheel, characterized by, The method comprises the following steps: Step 1, designing a frame structure of the diamond grinding wheel; Step 2, binder jetting a frame structure green body; Step 3, mixing diamond abrasives and fillers to obtain mixed powder; Step 4, filling the mixed powder into the frame structure green body, and then placing the green body filled with the powder on a vibration platform to vibrate and compact; Step 5, placing the green body filled with the powder into an atmosphere furnace to perform pre-sintering; Step 6, placing the brown part after pre-sintering into a vacuum furnace to perform bronze infiltration treatment; Step 7, removing impurities attached to the surface of the grinding wheel, and then performing grinding wheel dressing to expose the diamond abrasives. In the method, the amount of diamond, filler and bronze is calculated according to the following formula: M 金刚石 =C 砂轮 ×V 砂轮 / 1cm 3 ×0.88g M 填料 =D1×ρ 填料 ×(V 砂轮 ×P 框架 -M 金刚石 / (D1×ρ 金刚石 )) M 青铜 =ρ 青铜 ×(V 砂轮 ×P 框架 ×(1-D1)+V 砂轮 ×(1-P 框架 )×(1-D2)) where M 金刚石 is the amount of diamond powder, M 填料 is the amount of filler required, M 青铜 is the amount of bronze required for infiltration, p 填料 is the density of the filler material, p 金刚石 is the density of the diamond, p 青铜 is the density of the bronze, C 砂轮 is the abrasive concentration of the set grinding wheel, V 砂轮 is the volume of the grinding wheel, P 框架 is the porosity of the binder jet printed framework structure, excluding the internal porosity of the printed parts, D1 is the bulk density of the mixed powder of diamond, filler, D2 is the relative density of the binder jet printed framework parts.

2. The binder jet 3D printing forming method of a porous diamond grinding wheel according to claim 1, wherein, The frame structure in step 1 comprises a porous structure frame, and a skin layer is covered on the periphery of the porous structure frame, and a powder filling opening is reserved on the skin layer.

3. The binder jet 3D printing forming method of a porous diamond grinding wheel according to claim 1, wherein, In step 2, metal powder material used for printing the frame structure is selected according to the required structural strength of the grinding wheel and the processing object, and a binder jetting additive manufacturing method is used to form a frame structure green body.

4. The binder jet 3D printing forming method of a porous diamond grinding wheel according to claim 1, wherein, In step 3, diamond abrasives and fillers are weighed according to the required weight ratio, and are placed into a mixing container; stainless steel grinding balls with different sizes are added into the mixed powder according to a weight ratio of 1:1, and the mixed powder is mixed in a three-dimensional powder mixer until the mixed powder is uniformly mixed and there is no obvious segregation of components.

5. The binder jet 3D printing forming method of a porous diamond grinding wheel according to claim 1, wherein, In step 4, the vibration time and power are controlled to control the vibration of the mixed powder.

6. The binder jet 3D printing forming method of a porous diamond grinding wheel according to claim 1, wherein, In step 5, the pre-sintering temperature is much lower than the melting point of the metal.

7. The binder jet 3D printing forming method of a porous diamond grinding wheel according to claim 1, wherein, In step 7, if the skin structure exists on the working surface of the grinding wheel, the skin structure is removed together during the grinding wheel dressing.

8. A porous diamond grinding wheel, characterized by, The method is obtained by the binder jetting 3D printing forming method according to any one of claims 1-7.

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