阅读说明：本技术 一种基于双金属粉末注射成型的金刚石绳锯串珠制备方法 (Preparation method of diamond wire saw bead based on bimetal powder injection molding ) 是由 高忠麟 于 2019-09-12 设计创作，主要内容包括：本发明公开了一种基于双金属粉末注射成型的金刚石绳锯串珠制备方法,包括以下步骤：步骤A,将金属预合金粉末和高温型蜡基粘结剂进行加热捏合,然后造粒制成芯体注塑喂料；步骤B,将金属预合金粉末、金刚石颗粒和低温型蜡基粘结剂进行加热捏合,然后造粒制成金刚石合金胎体注塑喂料；步骤C,在双色注塑机连续注射成型,所述金刚石合金胎体注塑喂料包覆所述芯体毛坯,注塑成型为金刚石合金胎体和芯体融合为一体的金刚石串珠毛坯。通过双合金粉末冶金注塑成型工艺,制得金刚石合金胎体和芯体融合为一体的金刚石绳锯串珠,避免芯体与金刚石合金胎体发生分离而造成碎串珠和断绳现象,延长金刚石绳锯的使用寿命。(The invention discloses a preparation method of a diamond wire saw bead based on bimetallic powder injection molding, which comprises the following steps: step A, heating and kneading metal pre-alloy powder and a high-temperature wax-based binder, and then granulating to prepare a core injection molding feed; b, heating and kneading the metal pre-alloy powder, the diamond particles and the low-temperature wax-based binder, and then granulating to prepare a diamond alloy matrix injection molding feed; and step C, continuously injecting and molding in a double-color injection molding machine, wherein the diamond alloy matrix is injected and fed to coat the core body blank, and the diamond alloy matrix and the core body are fused into a diamond bead blank in an injection molding mode. The diamond wire saw bead integrated by the diamond alloy matrix and the core is prepared by a double-alloy powder metallurgy injection molding process, the phenomena of bead breaking and rope breaking caused by the separation of the core and the diamond alloy matrix are avoided, and the service life of the diamond wire saw is prolonged.)

1. A preparation method of a diamond wire saw bead based on bimetallic powder injection molding is characterized by comprising the following steps:

step A, heating and kneading metal pre-alloy powder and a high-temperature wax-based binder, and then granulating to prepare a core injection molding feed;

b, heating and kneading the metal pre-alloy powder, the diamond particles and the low-temperature wax-based binder, and then granulating to prepare a diamond alloy matrix injection molding feed;

step C, putting the core body injection molding feed into a charging barrel of one injection molding machine in a double-color injection molding machine, and putting the diamond alloy matrix injection molding feed into a charging barrel of the other injection molding machine; continuously injecting and molding in a double-color injection molding machine, namely injecting a core body injection molding feed into a mold cavity to form a core body blank, then injecting a diamond alloy matrix injection molding feed into the mold cavity, coating the core body blank with the diamond alloy matrix injection molding feed, and performing injection molding to form a diamond bead blank with the diamond alloy matrix and the core body integrated;

d, carrying out solvent degreasing treatment on the diamond bead blank;

e, performing vacuum thermal degreasing and vacuum pressure sintering on the diamond bead blank treated in the step D to prepare the diamond wire saw bead;

the difference of the sintering temperature of the core body injection molding feed and the diamond alloy matrix injection molding feed is less than 10 ℃, the difference of the shrinkage rate of the core body injection molding feed and the shrinkage rate of the diamond alloy matrix injection molding feed is less than 1%, and the melting point of the low-temperature type wax-based binder is lower than that of the high-temperature type wax-based binder.

2. The method for preparing the diamond wire saw bead based on the bimetal powder injection molding according to claim 1, wherein the method comprises the following steps: according to the mass percentage, the metal pre-alloy powder comprises 10-40% of electrolytic Cu powder, 7-30% of carbonyl Ni powder, 8-25% of CuSn15 pre-alloy powder, 5-20% of WC powder and 1-15% of Cr powder;

wherein the grain sizes of the electrolytic Cu powder and the CuSn15 pre-alloy powder are both 500 meshes, and the grain sizes of the carbonyl Ni powder, the WC powder and the Cr powder are all less than 2 mu m.

3. The method for preparing the diamond wire saw bead based on the bimetal powder injection molding according to claim 1, wherein the method comprises the following steps: the raw materials of the high-temperature wax-based binder comprise, by mass, 50-60% of fully refined paraffin, 5-15% of microcrystalline paraffin, 15-20% of high-density polyethylene, 5-10% of atactic polypropylene, 0.5-3% of dioctyl phthalate and 0.5-2% of stearic acid.

4. The method for preparing the bimetal powder injection molding-based diamond wire saw bead as claimed in claim 1, wherein the step A specifically comprises the following steps:

step A1, weighing 88-90% of metal pre-alloy powder and 10-12% of high-temperature wax-based binder according to mass percentage;

step A2, adding the high-temperature wax-based binder into a kneader and heating to 170-180 ℃;

step A3, after the high-temperature wax-based binder is melted, adding the metal pre-alloy powder into the kneader in the step A2 for multiple times, and adding new metal pre-alloy powder into the kneader each time after the original metal pre-alloy powder in the kneader is melted, and continuing heating and kneading for 0.5-1.5 hours by the kneader until all the metal pre-alloy powder is added to prepare a first kneaded material;

and step A4, taking the first kneaded material prepared in the step A3 out of the kneader, naturally cooling the first kneaded material, and crushing the first kneaded material into granular core injection molding feed materials by a crusher.

5. The method for preparing the diamond wire saw bead based on the bimetal powder injection molding according to claim 1, wherein the method comprises the following steps:

particle size of the metal prealloyed powder<5 μm, the specific surface area of the metal prealloy powder is less than or equal to 10m²/g；

The diamond particles have a particle size classification of 40% in a range of 35-40 mesh and 60% in a range of 40-50 mesh.

6. The method for preparing the diamond wire saw bead based on the bimetal powder injection molding according to claim 1, wherein the method comprises the following steps: the raw materials of the low-temperature wax-based binder comprise, by mass, 55-65% of fully refined paraffin, 2-5% of microcrystalline paraffin, 15-20% of low-density polyethylene, 10-20% of atactic polypropylene, 0.5-3% of dioctyl phthalate, 0.5-2% of stearic acid and 0.5-1% of high-polarity organic resin.

7. The method for preparing the diamond wire saw bead based on the bimetal powder injection molding according to claim 1, wherein the method comprises the following steps: the step B specifically comprises the following steps:

step B1, weighing 50-65% of metal pre-alloy powder and 35-50% of diamond particles according to the mass percentage, and filling the metal pre-alloy powder and the diamond particles into a mixing barrel to mix for 1-2 hours to prepare a first mixture;

step B2, weighing 88-90% of the first mixture and 10-12% of the low-temperature wax-based binder according to mass percentage;

step B3, adding the low-temperature wax-based binder into a kneader and heating to 150-160 ℃;

step B4, after the low-temperature wax-based binder is melted, adding the first mixture into the kneader in the step B3 for multiple times, and adding a new first mixture into the kneader each time after the original first mixture in the kneader is melted until all the first mixtures are added, and then continuously heating and kneading the kneader for 0.5-1.5 hours to obtain a second kneaded material;

and B5, taking the second kneaded material prepared in the step B4 out of the kneader, naturally cooling the second kneaded material, and crushing the second kneaded material into granular diamond alloy matrix by a crusher for injection molding feeding.

8. The method for preparing the diamond wire saw bead based on the bimetal powder injection molding according to claim 1, wherein the method comprises the following steps: in the step C, the mold clamping pressure of the double-color injection molding machine is 35-50 tons, the working temperature of the injection molding machine charging barrel provided with the core body injection molding feed is 180 ℃, and the working temperature of the injection molding machine charging barrel provided with the diamond alloy matrix injection molding feed is 160 ℃.

9. The method for preparing the bimetal powder injection molding-based diamond wire saw bead as claimed in claim 1, wherein the step D specifically comprises the following steps:

d1, soaking the diamond bead blank in trichloroethane for 6-8 hours at 50-60 ℃, then taking out the diamond bead blank and cleaning the diamond bead blank, wherein the weight of the trichloroethane in the step D1 is 5 times of that of the diamond bead blank;

and D2, soaking the diamond bead blank processed in the step D1 in new trichloroethane at the temperature of 50-60 ℃ for 2-3 hours, then taking out, cleaning and drying the diamond bead blank, wherein the weight of the trichloroethane in the step D2 is 3 times of that of the diamond bead blank.

10. The method for preparing the bimetal powder injection molding-based diamond wire saw bead as claimed in claim 1, wherein the step E specifically comprises the following steps:

step E1, putting the diamond bead blank processed in the step D into a vacuum pressure sintering furnace, wherein the vacuum degree of the vacuum pressure sintering furnace is less than 10Pa, the vacuum pressure sintering furnace is firstly heated from room temperature to 200 ℃ at the heating rate of 2 ℃/min, is heated to 400 ℃ at the heating rate of 2 ℃/min after being heated for 60min, is heated to 600 ℃ at the heating rate of 5 ℃/min;

e2, preserving the heat of the vacuum pressurization sintering furnace at 600 ℃ for 30min, introducing hydrogen, controlling the pressure in the furnace to be 0.1035MPa, and finishing vacuum thermal degreasing;

step E3, heating the vacuum pressure sintering furnace from 600 ℃ to 950 ℃ at the heating rate of 5 ℃/min, preserving the heat for 60min, and carrying out vacuum sintering;

e3, keeping the temperature of the vacuum pressurization sintering furnace at 950 ℃ for 30min, introducing argon gas, controlling the pressure in the furnace to be 6MPa, and performing hot isostatic pressing sintering;

and E4, stopping the operation of the vacuum pressurization sintering furnace, and cooling to room temperature to obtain the diamond wire saw bead.

Technical Field

The invention relates to the field of diamond wire saw beads, in particular to a preparation method of a diamond wire saw bead based on bimetallic powder injection molding.

Background

The diamond wire saw is formed by stringing cylindrical diamond wire saw beads on a steel wire rope and fixing each diamond wire saw bead by a rubber and plastic spacer sleeve to form a complete diamond wire saw, wherein the cylindrical diamond wire saw beads are composed of a cylindrical core body and a diamond alloy matrix body containing diamond particles on the periphery of the core body. However, in the existing preparation method of the diamond wire saw bead, the core body and the diamond alloy matrix are brazed into a whole in a hot-pressing sintering mode, and the core body and the diamond alloy matrix often have the problem of incomplete welding, so that the core body and the diamond alloy matrix are desoldered to cause bead breaking and rope breaking.

Disclosure of Invention

The invention aims to provide a method for preparing diamond wire saw beads based on bimetal powder injection molding, which is characterized in that the diamond wire saw beads with a diamond alloy matrix and a core body fused into a whole are prepared by a double-alloy powder metallurgy injection molding process, the phenomena of bead breaking and rope breaking caused by the separation of the core body and the diamond alloy matrix are avoided, and the service life of a diamond wire saw is prolonged.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a diamond wire saw bead based on bimetallic powder injection molding comprises the following steps:

step A, heating and kneading metal pre-alloy powder and a high-temperature wax-based binder, and then granulating to prepare a core injection molding feed;

b, heating and kneading the metal pre-alloy powder, the diamond particles and the low-temperature wax-based binder, and then granulating to prepare a diamond alloy matrix injection molding feed;

step C, putting the core body injection molding feed into a charging barrel of one injection molding machine in a double-color injection molding machine, and putting the diamond alloy matrix injection molding feed into a charging barrel of the other injection molding machine; continuously injecting and molding in a double-color injection molding machine, namely injecting a core body injection molding feed into a mold cavity to form a core body blank, then injecting a diamond alloy matrix injection molding feed into the mold cavity, coating the core body blank with the diamond alloy matrix injection molding feed, and performing injection molding to form a diamond bead blank with the diamond alloy matrix and the core body integrated;

d, carrying out solvent degreasing treatment on the diamond bead blank;

e, performing vacuum thermal degreasing and vacuum pressure sintering on the diamond bead blank treated in the step D to prepare the diamond wire saw bead;

the difference of the sintering temperature of the core body injection molding feed and the diamond alloy matrix injection molding feed is less than 10 ℃, the difference of the shrinkage rate of the core body injection molding feed and the shrinkage rate of the diamond alloy matrix injection molding feed is less than 1%, and the melting point of the low-temperature type wax-based binder is lower than that of the high-temperature type wax-based binder.

Through a double-alloy powder metallurgy injection molding process, namely step C, the core body blank is coated by the diamond alloy matrix injection molding feed, and the diamond bead blank is formed by injection molding to be a diamond bead blank formed by integrating the diamond alloy matrix and the core body, so that the problems that the core body and the diamond alloy matrix body are welded into a whole in a hot-pressing sintering mode and are welded incompletely frequently in the core body and the diamond alloy matrix body in the existing hot-pressing sintering process of the diamond wire saw bead are solved, and the phenomena of bead breaking and rope breaking caused by the desoldering of the core body and the diamond alloy matrix body are avoided.

In the prepared diamond wire saw bead, the core body is a support body of the diamond alloy matrix, so that the diamond alloy matrix containing diamond particles is prevented from directly contacting with the steel wire rope to abrade the steel wire rope, and the service life of the wire saw is prolonged. The difference of the sintering temperature of the core body injection molding feed and the diamond alloy matrix injection molding feed is less than 10 ℃, and the difference of the shrinkage rate of the core body injection molding feed and the diamond alloy matrix injection molding feed is less than 1%, so that the sintered diamond alloy matrix and the core body can be fused into a whole.

Preferably, the metal pre-alloy powder comprises, by mass, 10% -40% of electrolytic Cu powder, 7% -30% of carbonyl Ni powder, 8% -25% of CuSn15 pre-alloy powder, 5% -20% of WC powder and 1% -15% of Cr powder; wherein the grain sizes of the electrolytic Cu powder and the CuSn15 pre-alloy powder are both 500 meshes, and the grain sizes of the carbonyl Ni powder, the WC powder and the Cr powder are all less than 2 mu m.

The core body injection molding feed and the diamond alloy matrix injection molding feed use metal pre-alloy powder with the same formula, so that the component compatibility of the core body injection molding feed and the diamond alloy matrix injection molding feed is high, the diamond alloy matrix and the core body are integrated, and the holding force on diamond particles is improved. The metal pre-alloy powder has high hardness and high impact strength, and can be directly prepared into a core body injection molding feed with a high-temperature wax-based binder and a diamond alloy matrix injection molding feed, so that the sintered diamond alloy matrix and the core body have high compressive strength and bending strength. The various powders in the metal prealloyed powder are commercially available from the existing market.

Preferably, the raw materials of the high-temperature wax-based binder comprise, by mass, 50-60% of fully refined paraffin, 5-15% of microcrystalline paraffin, 15-20% of high-density polyethylene, 5-10% of atactic polypropylene, 0.5-3% of dioctyl phthalate, and 0.5-2% of stearic acid.

The fully refined paraffin, microcrystalline paraffin and Stearic Acid (SA) in the high-temperature wax-based binder can promote injection, so that the problem that the injection molding feeding of the core body is difficult to inject due to too high viscosity is avoided; high Density Polyethylene (HDPE) and random polypropylene (APP) play a role of a framework in the degreasing process, and the core body blank is prevented from collapsing during degreasing; dioctyl phthalate (DOP) acts as a dispersing agent. Since the core is used as a support and has a high structural strength requirement, high-density polyethylene is used to improve the mechanical strength, and atactic polypropylene is used to improve the toughness. The fully refined paraffin and the microcrystalline paraffin also play a role of a filler, and the fully refined paraffin with the paraffin content lower than 0.8 percent is used as a main filler, so that the degreasing time can be greatly shortened.

Preferably, the step a specifically includes:

step A1, weighing 88-90% of metal pre-alloy powder and 10-12% of high-temperature wax-based binder according to mass percentage;

step A2, adding the high-temperature wax-based binder into a kneader and heating to 170-180 ℃;

step A3, after the high-temperature wax-based binder is melted, adding the metal pre-alloy powder into the kneader in the step A2 for multiple times, and adding new metal pre-alloy powder into the kneader each time after the original metal pre-alloy powder in the kneader is melted, and continuing heating and kneading for 0.5-1.5 hours by the kneader until all the metal pre-alloy powder is added to prepare a first kneaded material;

and step A4, taking the first kneaded material prepared in the step A3 out of the kneader, naturally cooling the first kneaded material, and crushing the first kneaded material into granular core injection molding feed materials by a crusher.

According to the mass percentage, 88-90% of metal pre-alloy powder and 10-12% of high-temperature wax-based binder are weighed, and the size shrinkage of the sintered product is small and is about 1.18-1.20. After the high-temperature wax-based binder is melted, in order to avoid the phenomenon that the melting and kneading time is too long due to the fact that the metal pre-alloy powder is added all at once, the metal pre-alloy powder is oxidized under the action of high temperature, so that the metal pre-alloy powder is added for multiple times, and a layer of high-temperature wax-based binder film can be quickly wrapped on the surface of the metal pre-alloy powder particles during each adding, so that the metal pre-alloy powder particles are isolated from air, and the metal pre-alloy powder particles are prevented from being oxidized. For example, the metal prealloyed powder may be added in four separate additions: 1/2 of the total amount of the metal pre-alloy powder is added for the first time, after the materials are completely melted, 1/2 of the balance is added for the second time, 1/2 of the balance is added for the third time, finally, the balance is completely added, heating and kneading are continued for 1 hour, a heating power supply is closed, the mixture is naturally cooled into blocks, and the blocks are crushed into granular core bodies by a crusher for injection molding feeding.

Preferably, the particle size of the metal prealloyed powder<5 μm, said metal prealloyingThe specific surface area of the powder is less than or equal to 10m²(ii)/g; the diamond particles have a particle size classification of 40% in a range of 35-40 mesh and 60% in a range of 40-50 mesh.

Particle size of the metal prealloyed powder<5 μm, thereby having high sintering reaction activity and low sintering temperature; the specific surface area of the metal prealloy powder is less than or equal to 10m²The specific surface area is smaller, and the using amount of the binder can be reduced. The diamond particles have reasonable granularity grading, and the cutting performance and the holding force of the metal pre-alloy powder on the diamond particles are improved.

Preferably, the raw materials of the low-temperature wax-based binder comprise, by mass, 55-65% of fully refined paraffin, 2-5% of microcrystalline paraffin, 15-20% of low-density polyethylene, 10-20% of atactic polypropylene, 0.5-3% of dioctyl phthalate, 0.5-2% of stearic acid and 0.5-1% of high-polarity organic resin.

The low-temperature wax-based binder uses low-density polyethylene (LDPE) as a framework material, has good extensibility and processability, and ensures that no crack or crack is generated when the diamond alloy matrix injection molding feed wraps the core body blank; the softening point of the low-density polyethylene is lower than that of the high-density polyethylene, so that the melting point of the low-temperature wax-based binder is lower than that of the high-temperature wax-based binder, and the reason is that one of the two wax-based binders is low-temperature binder and the other is high-temperature binder;

the low-temperature wax-based binder is also added with 0.5-1% of high-polarity organic resin, such as Arabic gum, so that the cohesiveness can be improved, the cohesiveness of the low-temperature wax-based binder is higher than that of the high-temperature wax-based binder, and thus, the low-temperature wax-based binder with low melting point and high cohesiveness is beneficial to the injection molding and feeding of a diamond alloy matrix to be well adhered to a core body blank, and the condition of delamination is avoided.

Preferably, the step B specifically includes:

step B1, weighing 50-65% of metal pre-alloy powder and 35-50% of diamond particles according to the mass percentage, and filling the metal pre-alloy powder and the diamond particles into a mixing barrel to mix for 1-2 hours to prepare a first mixture;

step B2, weighing 88-90% of the first mixture and 10-12% of the low-temperature wax-based binder according to mass percentage;

step B3, adding the low-temperature wax-based binder into a kneader and heating to 150-160 ℃;

step B4, after the low-temperature wax-based binder is melted, adding the first mixture into the kneader in the step B3 for multiple times, and adding a new first mixture into the kneader each time after the original first mixture in the kneader is melted until all the first mixtures are added, and then continuously heating and kneading the kneader for 0.5-1.5 hours to obtain a second kneaded material;

and B5, taking the second kneaded material prepared in the step B4 out of the kneader, naturally cooling the second kneaded material, and crushing the second kneaded material into granular diamond alloy matrix by a crusher for injection molding feeding.

The metal pre-alloy powder and the diamond particles are uniformly mixed to ensure that the diamond particles on the prepared diamond alloy matrix are uniformly distributed. Because large-particle diamonds in the diamond alloy matrix do not shrink during sintering, in order to correct shrinkage parameters, the mass percentage of the low-temperature wax-based binder is preferably increased by 0.5% compared with the mass percentage of the high-temperature wax-based binder, for example, when the mass percentage of the high-temperature wax-based binder in the core injection molding feeding is 11.5%, the mass percentage of the low-temperature wax-based binder in the diamond alloy matrix injection molding feeding is correspondingly 12%, so as to ensure that the sintered diamond alloy matrix and the core are fused together.

After the low-temperature wax-based binder is melted, in order to avoid the phenomenon that the first mixture is added completely at one time to cause melting and overlong kneading time, the metal pre-alloy powder is oxidized under the action of high temperature, so that the first mixture is added for multiple times, and a layer of low-temperature wax-based binder film can be quickly wrapped on the surface of the first mixture particles during each addition, so that the first mixture particles are isolated from air, and the first mixture particles are prevented from being oxidized. For example, the first mix may be added in four times: 1/2 of the total amount of the first mixture is added for the first time, after the materials are completely melted, 1/2 of the balance is added for the second time, 1/2 of the balance is added for the third time, finally, the balance is completely added, heating and kneading are continued for 1 hour, a heating power supply is closed, the mixture is naturally cooled to be blocks, and the blocks are crushed into granular diamond alloy matrix bodies by a crusher to be injected and fed.

Preferably, in the step C, the mold clamping pressure of the double-color injection molding machine is 35 to 50 tons, the working temperature of the injection molding machine charging barrel provided with the core body injection molding feed is 180 ℃, and the working temperature of the injection molding machine charging barrel provided with the diamond alloy matrix injection molding feed is 160 ℃.

The mold closing pressure of the double-color injection molding machine is 35-50 tons, the mold is separated from the seam and the flash phenomenon is caused when the mold closing pressure is smaller than the range, and the mold is deformed and the blank generates internal stress when the mold closing pressure is larger than the range. Because the melting point of the low-temperature wax-based binder is lower than that of the high-temperature wax-based binder, the working temperature of the charging barrel of the injection molding machine provided with the diamond alloy matrix injection feed is lower than that of the charging barrel of the injection molding machine provided with the core injection feed.

Preferably, the step D specifically includes:

d1, soaking the diamond bead blank in trichloroethane for 6-8 hours at 50-60 ℃, then taking out the diamond bead blank and cleaning the diamond bead blank, wherein the weight of the trichloroethane in the step D1 is 5 times of that of the diamond bead blank;

and D2, soaking the diamond bead blank processed in the step D1 in new trichloroethane at the temperature of 50-60 ℃ for 2-3 hours, then taking out, cleaning and drying the diamond bead blank, wherein the weight of the trichloroethane in the step D2 is 3 times of that of the diamond bead blank.

Solvent degreasing is to use a solution which can dissolve a certain component in a binder in a blank before sintering, and the binder is dissolved out of the blank by soaking. The oil-soluble solvent-trichloroethane is adopted to dissolve the fully refined paraffin and the microcrystalline paraffin, and the trichloroethane is not easy to burn and is safer; and the method of multi-step extraction can be adopted to better remove the fully refined paraffin and microcrystalline paraffin in the diamond bead blank. And D1 and D2, wherein in the step D1, 60-70% of fully refined paraffin and microcrystalline paraffin in the diamond bead blank can be removed, and in the step D2, new trichloroethane is used for degreasing, so that about 90% of the balance of the fully refined paraffin and microcrystalline paraffin can be removed, therefore, the residual amount of the fully refined paraffin and microcrystalline paraffin in the diamond bead blank after the step D is less, and the efficiency of subsequent vacuum thermal degreasing can be improved.

Preferably, the step E specifically includes:

step E1, putting the diamond bead blank processed in the step D into a vacuum pressure sintering furnace, wherein the vacuum degree of the vacuum pressure sintering furnace is less than 10Pa, the vacuum pressure sintering furnace is firstly heated from room temperature to 200 ℃ at the heating rate of 2 ℃/min, is heated to 400 ℃ at the heating rate of 2 ℃/min after being heated for 60min, is heated to 600 ℃ at the heating rate of 5 ℃/min;

e2, preserving the heat of the vacuum pressurization sintering furnace at 600 ℃ for 30min, introducing hydrogen, controlling the pressure in the furnace to be 0.1035MPa, and finishing vacuum thermal degreasing;

step E3, heating the vacuum pressure sintering furnace from 600 ℃ to 950 ℃ at the heating rate of 5 ℃/min, preserving the heat for 60min, and carrying out vacuum sintering;

e3, keeping the temperature of the vacuum pressurization sintering furnace at 950 ℃ for 30min, introducing argon gas, controlling the pressure in the furnace to be 6MPa, and performing hot isostatic pressing sintering;

and E4, stopping the operation of the vacuum pressurization sintering furnace, and cooling to room temperature to obtain the diamond wire saw bead.

Vacuum thermal degreasing utilizes the vacuum effect to improve the vapor pressure of the high polymer, promote decomposition, reduce degreasing residues and accelerate degreasing speed and efficiency. About 30 percent of high-density polyethylene, low-density polyethylene, high-molecular ethylene which is not dissolved in organic solvent and other residual components are remained in the diamond bead blank after solvent degreasing, and can be removed only by thermal decomposition of vacuum thermal degreasing.

The existing preparation method of the diamond wire saw bead adopts cold press molding to prepare a blank, the blank of the bead is pre-sintered under no pressure in the first step, hot isostatic pressing sintering is carried out in the second step, the two-time high-temperature sintering has long cycle time, large power consumption, multiple working procedures, unstable quality, large required pressure (the pressure of common hot isostatic pressing is 100 MPa-200 MP), large using amount of high-purity Ar argon and high cost.

And step E, the diamond bead blank is placed into a vacuum pressure sintering furnace to complete the whole process of the four-step process of thermal degreasing, alloy powder hydrogen reduction, vacuum sintering and hot isostatic pressing sintering at one time, so that the diamond bead blank is prevented from contacting with air in repeated processes of thermal degreasing, hydrogen reduction, vacuum sintering, hot isostatic pressing sintering and the like to increase the chance of oxidation pollution, the quality is guaranteed, the production period and energy consumption are reduced, the production efficiency is improved, the manual strength is reduced, and the energy consumption and the environmental pollution are greatly reduced.

The vacuum degree of the vacuum pressurization sintering furnace in the step E1 is less than 10Pa, the resin and residues in the binder are more easily decomposed and volatilized when the vacuum degree is higher, and the carbon deposition effect of the diamond bead blank is reduced.

The metal pre-alloy powder is inevitably polluted by water mist, air and the like in the processes of mixing, injection molding and solvent degreasing, so that an oxide layer is generated on the surface of the metal pre-alloy powder particle. Step E2, introducing hydrogen in the vacuum thermal degreasing tail section process to reduce the oxidation and pollution of the surface of the metal pre-alloy powder particles in the mixing, injection molding and solvent degreasing processes, thereby enhancing the carbonization of diamond alloy matrix components on the surface of the diamond particles and the holding force of the diamond particles, enhancing the reaction activity of particle sintering due to the reduction of the surface of the metal pre-alloy powder, reducing the sintering temperature, improving the sintering density of the diamond alloy matrix, and approaching 100% of theoretical density.

E3, adding argon gas to perform hot isostatic pressing sintering, improving the density and strength of the diamond wire saw bead, and reducing the defects of air holes and cracks in the diamond wire saw bead; the pressure required by the existing hot isostatic pressing sintering furnace is reduced from 100MPa to 200MPa to 6MPa, so that the using amount of high-purity argon is greatly reduced, and the same technical requirements can be met.

According to the preparation method of the diamond wire saw bead based on the bimetal powder injection molding, firstly, a core injection molding feed and a diamond alloy matrix injection molding feed are respectively prepared, and then the core blank is coated by the diamond alloy matrix injection molding feed through a double alloy powder metallurgy injection molding process, namely step C, so that the diamond alloy matrix injection molding feed is injection molded into the diamond bead blank which is formed by fusing a diamond alloy matrix and a core together, and the problems that the core and the diamond alloy matrix are brazed into a whole through a hot-pressing sintering mode in the existing hot-pressing sintering process of the diamond wire saw bead, and the core and the diamond alloy matrix are often incompletely welded, so that the core and the diamond alloy matrix are detached from each other to cause bead breaking and rope breaking phenomena are avoided; the limitation of cold press molding on the shape and the size of the diamond wire saw bead is solved, and the diamond wire saw bead with any shape and size can be produced according to different requirements; the diamond wire saw bead blank is manufactured into a powder metallurgy injection molding product with two different functions on the same diamond wire saw bead blank.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments.