Preparation method of a new type of process beads

Abstract

The present invention discloses a preparation method of a novel process bead, comprising the following steps: calculating the required weight according to the specifications and quantity of the beads, adding special powder for pressureless sintering, superfine iron powder, WC powder, etc. according to the corresponding ratio, putting the prepared powder into a three-dimensional mixer for mixing, then adding diamond and granulating agent, and mixing again; after mixing, pouring the mixture into a granulator for granulation; subjecting the granulated powder to cold pressing by an automatic press; putting the beads into a matrix and placing them together in a vacuum furnace for sintering to obtain a novel process bead string. The present invention not only has simple production procedures, high efficiency and low cost, but also the beads produced by this method have the advantages of good self-sharpening property, high sawing efficiency, high diamond holding force and excellent comprehensive performance.

Description

Technical Field

[0001] The invention relates to the field of diamond tool bead processing, in particular to a preparation method of a new type of process bead. Background Art

[0002] Beaded rope has become an indispensable tool for stone mining and plate processing due to its advantages of high yield rate, good processing quality, not easy to damage rough materials, high production efficiency, and little pollution during cutting and mining. With the increasing number of diamond beaded rope saw manufacturers, fierce competition, the price of beaded rope continues to decrease, and the combination rope saw continues to develop towards small diameter beads, traditional hot-pressed sintered beads are facing a series of problems such as high production cost, cumbersome production process, low production efficiency of small diameter beads, and poor self-sharpening of marble beads.

[0003] The use of pressureless sintering not only simplifies the production process, but also reduces the cost of cold pressing and sintering. In addition, since hot pressing graphite molds are not required, it is convenient to reduce the diameter of beads. However, the current pressureless sintering process still faces the following three problems:

[0004] 1) The beaded ring is first sintered, and then the beaded ring is brazed with the iron matrix, which has a complicated production process and high production cost;

[0005] 2) The beaded ring cold pressed billet is sintered together with the iron matrix, but there is a high cracking rate and the production cost cannot be reduced;

[0006] 3) There is no additional pressure during the conventional free sintering process, so the bonding strength of the beads to the diamond is low, the diamond is easy to fall off during the cutting process, the bead rope has a short life, and the cost performance is low.

[0007] Therefore, providing a new method for preparing beads without pressure sintering is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0008] In view of this, the present invention provides a method for stringing beads using a new production process.

[0009] To achieve the above object, the present invention adopts the following technical solution:

[0010] A method for preparing a novel process bead string comprises the following steps:

[0011] (1) Ingredients: The required powder is calculated according to the specifications and quantity of the beads to be produced, and the ingredients are prepared according to the mass percentage of 65-80% of special pressureless sintering powder, 10-30% of ultrafine iron powder, and 5-15% of WC; the ultrafine iron powder and WC are added in the present invention to adjust the hardness and wear resistance of the matrix so that the beads have better versatility;

[0012] (2) Mixing: Put the sintered pressureless sintered powder into a three-dimensional mixer for mixing, then add diamond and granulating agent, and mix again;

[0013] (3) Granulation: Pour the mixed material into a granulator for granulation after mixing;

[0014] (4) Cold pressing: Cold press the granulated powder with an automatic press to obtain beads;

[0015] (5) Sintering: Put the beads on the substrate and put them into a vacuum furnace for sintering to obtain a new type of process bead string.

[0016] Furthermore, the composition of the special pressureless sintered powder described in step (1) includes the following components by weight percentage: Fe 76 - 77%, Cu 12 - 13%, Ni 7 - 8%, P 1.8 - 2.2%, V 0.9 - 1.2%.

[0017] The beneficial effects of adopting the above further scheme are as follows: The properties of iron in the above powder are close to those of cobalt, and the price is low. Its adhesion to diamond is even higher than that of cobalt. It has economic benefits that cannot be compared by other binders. Therefore, the special powder is mainly composed of iron. At the same time, due to the narrow sintering temperature range of the iron-based and insufficient self-sharpening, the best addition ratio of copper is determined to be 10 - 15% through experiments. In addition, since iron and copper are basically immiscible, Ni is added as a bridge and to improve the properties of the matrix. The addition of P plays a role in promoting sintering, and the alloy formed by P and Fe is brittle, which can well improve the self-sharpening of the matrix and improve the sharpness of the product. V is a strong carbide-forming element, which can react with diamond at the interface to generate VC, enrich on the diamond surface, and at the same time can significantly improve the hardness of the matrix and the holding force of the matrix for diamond through solid solution strengthening, and improve the life of the matrix. Therefore, based on theory and a large amount of experimental data, the optimal ratio of Fe, Cu, Ni, P, and V is determined to ensure that the matrix has sufficient holding force for diamond to ensure the life of the diamond tool. At the same time, the matrix also has the performance of synchronous wear with diamond, making the tool prepared by it have excellent efficiency.

[0018] Even further, the sintering method described in step (1) is: Sinter and produce the weighed special pressureless sintered powder by the combined water-vapor atomization method. Select powders with a particle size of 2000 - 3000 mesh. Sinter the powder at 600 - 700 °C in air for 2 h, then introduce nitrogen to replace the air in the furnace, and introduce H2 or ammonia decomposition gas (N2 + H2) to continue sintering the powder in a reducing atmosphere for 1 h.

[0019] The beneficial effects of adopting the above further scheme are as follows: The cold compaction granulation property of the powder in the above scheme can be improved well. The above sintering method exposes new bonds at the oxygen molecule bonding sites, further enhancing the sintering activity. At the same time, the cold compaction granulation property of the powder after reduction is also further improved. Using powder with a particle size of 2000 - 3000 mesh has a large specific surface area, high powder activity, a large driving force during free sintering, and a high sintering density.

[0020] Further, in step (2), the diamond particle size is 35# - 60#, and the addition ratio is 2 - 3.5% of the powder weight; an acrylic resin granulating agent is added, and the addition amount is 2 - 5% of the total powder mass.

[0021] Further, the granulation method in step (3) is as follows: Pour the mixture into a granulator, set the rotation speed of the granulator at 800 - 1500 r / min, the granulation time is 2 - 15 min. After granulation, pass through 30 - mesh and 80 - mesh sieves, and re - granulate the materials on the 30 - mesh sieve and the materials under the 80 - mesh sieve.

[0022] The beneficial effects of adopting the above further scheme are as follows: Granulating under the above conditions can make the produced particles have a narrow particle size range interval, good particle size uniformity, and at the same time, the particles have high strength and are not easily broken. In addition, powders with a particle size of 30 - 80 mesh are cold - pressed. The powder particles in this interval have good cold - pressing fluidity, stable cold - pressing weight, and high green compact strength.

[0023] Further, in step (4), the cold pressing is carried out by the constant - volume method for automatic cold pressing. The cold - pressing weight is controlled by adjusting the relative position of the punch and the cavity. The granulated powder enters the cavity from the cold press. After the powder is leveled, 4 - 16 beads are cold - pressed simultaneously at one time. The cold - pressing height is 6 - 9 mm, the pressure is 300 - 600 MPa, and the pressure - holding time is 2 - 3 s.

[0024] The beneficial effects of adopting the above further scheme are as follows: In the above scheme of the present invention, since the volume of each cavity is the same, the loose - packing density of the granulated powder is stable, and the weight of each bead has a high consistency. 4 - 16 beads can be cold - pressed simultaneously at one time, having a very high pressing efficiency. In addition, since the higher the cold - pressing pressure, the higher the density of the powder, and at the same time, the greater the pressure on the diamond and the cold - pressing die, both the strength of the diamond and the life of the cold - pressing die are affected. Therefore, through comprehensive comparative tests, 300 - 600 MPa is the optimal cold - pressing pressure. And when the pressure is determined, the shrinkage rate after sintering is also determined. Therefore, according to the size requirements after sintering, controlling the powder height at 6 - 9 mm and holding the pressure for 2 - 3 s can ensure that the size is in place and avoid delamination and cracking during the cold - pressing process.

[0025] Further, in step (5), the substrate is an iron substrate with an outer diameter of 5 - 8 mm. After cold pressing, the inner diameter of the bead is 0.01 - 0.04 mm larger than the outer diameter of the iron substrate.

[0026] The beneficial effects of adopting the above further scheme are as follows: Since the inner diameter size of the bead is a very important parameter, which directly determines the qualification rate of the sintered product, and the whole size is directly related to the pressing force, the powder ratio and element ratio of the matrix, it is necessary to comprehensively consider the particle size of the powder, the characteristics of different elements, and the density of cold pressing. Through analysis and comparison, using a special pressureless sintering powder, at a cold pressing pressure of 300 - 600 MPa, holding the pressure for 2 - 3 s, and the inner diameter of the bead being 0.01 - 0.04 mm larger than the iron substrate can make the bead matrix and the iron substrate have very good bonding strength. At the same time, the product will not crack or delaminate, and the outer diameter size of the bead has good uniformity.

[0027] Furthermore, in step (5), the sintering method is: put the bead on the iron substrate, place it on a ceramic plate, and then put it into a vacuum sintering furnace for sintering;

[0028] The sintering temperature of 25 - 450 °C is atmospheric pressure sintering, with a heating rate of 3 - 5 °C / min. After holding at 450 °C for 30 min, start to pump vacuum, and keep the vacuum degree at 1×10 -3 ~10 -2 MPa, then heat up. During the process of 450 °C - 800 °C, the heating rate is 1.5 - 3 °C / min, and from 800 °C to the final sintering temperature, the heating rate is 0.5 - 1 °C / min. The final sintering temperature is 810 - 950 °C, and the holding time at the final sintering temperature is 1 h. Then cool down at a rate of 3 - 5 °C / min to 600 °C, and then cool naturally with the furnace to room temperature.

[0029] Sintering under the above vacuum degree adopted in the present invention can promote the alloying of the powder and is beneficial to the exclusion of gas, avoiding affecting the density due to the remaining pores inside the matrix after sintering. At the same time, considering the influence of the heating rate on production efficiency and the requirement of temperature uniformity inside and outside the product, the heating rate from 800 °C to the final sintering temperature is set at 0.5 - 1 °C / min, which can meet the energy requirements and diffusion time requirements corresponding to the powder alloying process and the corresponding metal phase transformation at this stage. And setting the final sintering temperature at 810 - 950 °C and the holding time at 1 h can make the matrix have a certain chemical bond type combination with the diamond, thereby improving the holding force of the matrix for the diamond; then cooling at a rate of 3 - 5 °C to 600 °C can avoid the formation of a hard and brittle compound on the surface of the bead due to too fast cooling rate, affecting the use of the product.

[0030] The beneficial effects of the present invention are as follows:

[0031] 1) The present invention directly sintered the beads together with the matrix, solving the problems of multiple production processes and high production costs in sintering first and then welding.

[0032] 2) The present invention uses a special pressureless sintering powder. And for the powder composition and powder performance requirements, a special production process is adopted, and a corresponding sintering method is formulated to meet the energy requirements during metal phase transformation. And the inner diameter of the beads after cold pressing is strictly controlled, solving the problems of high cracking rate of the beads and high rejection rate, and the rejection rate can be controlled within 1%.

[0033] 3) By studying the driving force of powder shrinkage during the non - pressurized production process, P element promoting sintering is added, and the sintered density is high. And V forming strong carbides is added, which effectively promotes the bonding strength between the matrix and the diamond. During the cutting process, the diamond is not easy to fall off, and has a good height of cutting edge. The self - sharpening of the bead string is good, and the cutting efficiency is high, well solving the problems such as easy falling off of conventional free - sintered diamonds and short service life of the bead string. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the preparation flow chart of the new - type process beads provided by the present invention;

[0035] Figure 2 is the schematic structural diagram of the cold - pressing die provided by the present invention;

[0036] Figure 3 is the state diagram of the diamond on the surface of the beads after a 120m 2 granite is cut respectively by the bead string prepared by the conventional pressureless sintering and the new - type process of the present invention. Among them, Figure 3a is the bead string of conventional pressureless sintering, Figure 3b is the bead string prepared by the new - type process of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0038] Embodiment 1

[0039] A preparation method of new - type process beads, characterized by including the following steps:

[0040] (1) Preparation of special powder for pressureless sintering: Select special pressureless sintering powder, whose composition is Fe 76.5%, Cu 12.5%, Ni 8%, P 2%, V 1%. This special pressureless sintering powder is produced by steam and gas combined atomization method. Select powder with a particle size of 2000 - 3000 mesh. Sinter the powder in air at 750 °C for 2 h, then introduce nitrogen to replace the air in the furnace, and then introduce H2 or ammonia decomposition gas to continue sintering the powder in a reducing atmosphere for 1 h;

[0041] (2) Batching: Calculate the required powder according to the specifications and quantity of the beads to be produced. The percentage of special pressureless sintering powder is 70%, and add 25% of superfine iron powder and 5% of WC. The beads sintered with this ratio have moderate hardness and good sharpness;

[0042] (3) Mixing: Put the pressureless sintering powder, superfine iron powder, and WC into a three - dimensional mixer for mixing, then add 2% diamond and 5% granulating agent, and mix again;

[0043] (4) Granulation: Pour the mixed material into a granulator. The addition amount of the granulating agent is 2.5% of the mass of the mixed material. Set the rotation speed of the granulator at 1000 r / min, and the granulation time is 10 min. After granulation, pass through 30 - mesh and 80 - mesh sieves, and re - granulate the materials on the 30 - mesh sieve and under the 80 - mesh sieve;

[0044] (5) Cold pressing: Adopt the constant - volume method for automatic cold pressing. Control the cold - pressing weight by adjusting the relative position of the punch and the cavity. The granulated powder enters the cavity from the cold press. After the powder is leveled, cold - press 9 beads simultaneously at one time. The cold - pressing height is 8 mm, the pressure is 300 MPa, and the pressure - holding time is 2 s;

[0045] (6) Sintering: Put the beads on the iron matrix, place them on a ceramic plate, and then put them into a vacuum sintering furnace for sintering; The outer diameter of the iron matrix is 7 mm, and the inner diameter of the bead after cold pressing is 0.03 mm larger than the outer diameter of the iron matrix; The sintering temperature is 25 - 450 °C for atmospheric pressure sintering, and the heating rate is 5 °C / min. Start to pump vacuum after holding at 450 °C for 30 min, and keep the vacuum degree at 5×10 -2 MPa, then heat up. The heating rate is 3 °C / min during the process of 450 °C - 800 °C, and the heating rate is 1 °C / min from 800 °C to the final sintering temperature. The final sintering temperature is 900 °C, and the holding time at the final sintering temperature is 1 h. Then cool down to 600 °C at a rate of 5 °C / min, and then cool down to room temperature naturally with the furnace.

[0046] Figure 3 shows the diamond states on the surfaces of the bead ropes prepared by conventional pressureless sintering and Example 1 of the present invention using the new process respectively after cutting a piece of granite about 120 m 2 respectively.Figure 3a It can be seen that for the conventional bead wire prepared by pressureless sintering, due to the insufficient holding force of the matrix for the diamond, a large area of diamond shedding occurs. At the same time, the protrusion height of the diamond is low, so the cutting efficiency is not high. Figure 3b For the bead wire prepared by the new process, due to the high holding force of the matrix for the diamond, the diamond shedding is very little. The failure form of the diamond is mainly the fragmentation at the front end of the bead due to the large impact force. At the same time, the protrusion height of the diamond is high, and the sharpness of the bead wire is good.

[0047] Table 1 shows the cutting efficiency and service life of the bead wire prepared by the conventional pressureless sintering and the bead wire prepared by the new process in Example 1 respectively.

[0048] Table 1 Cutting data of the bead wire of the conventional process and the new process

[0049]

[0050] It is not difficult to find from Table 1 that for the bead wire prepared by the new process, due to the use of a special powder developed specifically for pressureless sintering and combined with a special sintering process, the holding force of the bead matrix for the diamond is much better, and the diamond is not easy to fall off. Therefore, the service life is much longer. At the same time, due to the high exposure height of the diamond, the average efficiency is also much higher than that of the conventional pressureless sintering.

[0051] Example 2

[0052] (1) Preparation of the special powder for pressureless sintering: Select the special powder for pressureless sintering, whose composition is Fe 77%, Cu 13%, Ni 7%, P 1.9%, V 1.1%. This special powder for pressureless sintering is produced by sintering with the combined method of water vapor atomization. Select the powder with a particle size of 2000 - 3000 mesh. Sinter the powder in the air at 750 °C for 2 h, then introduce nitrogen to replace the air in the furnace, and then introduce H2 or ammonia decomposition gas to continue sintering the powder in a reducing atmosphere for 1 h;

[0053] (2) Batching: Calculate the required powder according to the specifications and quantity of the beads to be produced. The percentage of the special powder for pressureless sintering is 75%, and add 10% of ultrafine iron powder and 15% of WC. The hardness of this formulated powder is relatively high, the wear resistance is very good, and it has an excellent service life;

[0054] (3) Mixing: Put the sintered powder for pressureless sintering into a three-dimensional mixer for mixing, then add 3% of diamond and 3% of granulating agent, and mix again;

[0055] (4) Granulation: Pour the mixed material into a granulator. The addition amount of the granulating agent is 5% of the mass of the mixed material. Set the rotation speed of the granulator at 800 r / min, and the granulation time is 15 min. After granulation, sieve through 30-mesh and 80-mesh sieves, and re-granulate the materials on the 30-mesh sieve and under the 80-mesh sieve;

[0056] (5) Cold pressing: Automatically perform cold pressing by the constant volume method. Control the cold pressing weight by adjusting the relative position of the punch and the cavity. The granulated powder enters the cavity from the cold press. After the powder is leveled, 16 beads are cold pressed simultaneously at one time. The cold pressing height is 6 mm, the pressure is 600 MPa, and the pressure holding time is 2 s;

[0057] (6) Sintering: Put the beads on the iron matrix, place them on a ceramic plate, and then put them into a vacuum sintering furnace for sintering; The outer diameter of the iron matrix is 8 mm, and the inner diameter of the bead after cold pressing is 0.01 mm larger than the outer diameter of the iron matrix; The sintering temperature is 25 - 450 °C for atmospheric pressure sintering, the heating rate is 3 °C / min. After holding at 450 °C for 30 min, start to evacuate, and keep the vacuum degree at 1×10 -3 MPa, then heat up. During the process of 450 °C - 800 °C, the heating rate is 1.5 °C / min. From 800 °C to the final sintering temperature, the heating rate is 0.5 °C / min. The final sintering temperature is 810 °C, and the holding time at the final sintering temperature is 1 h. Subsequently, cool down to 600 °C at a rate of 3 °C / min, and then cool down to room temperature naturally with the furnace.

[0058] Example 3

[0059] A preparation method of a new type of process bead string, characterized by comprising the following steps:

[0060] (1) Preparation of the special powder for pressureless sintering: Select the special powder for pressureless sintering, whose composition is Fe 76%, Cu 13%, Ni 7.7%, P 2.2%, V 1.1%. This special powder for pressureless sintering is produced by the combined water vapor atomization method. Select the powder with a particle size of 2000 - 3000 mesh. Sinter the powder in the air at 750 °C for 2 h, then introduce nitrogen to replace the air in the furnace, and then introduce H2 or ammonia decomposition gas to continue sintering the powder in a reducing atmosphere for 1 h;

[0061] (2) Batching: Calculate the required powder according to the specifications and quantities of the beads to be produced. The percentage of the special powder for pressureless sintering is 70%, and add 20% of ultra-fine iron powder and 10% of WC. The beads produced by this ratio take into account both efficiency and lifespan and have excellent comprehensive performance;

[0062] (2) Mixing: Put the sintered special powder for pressureless sintering into a three-dimensional mixer for mixing, then add 3.5% diamond and 2% granulating agent, and mix again;

[0063] (3) Granulation: Pour the mixed material into a granulator. The addition amount of the granulating agent is 2% of the mass of the mixed material. The rotation speed of the granulator is set at 1500 r / min, and the granulation time is 2 min. After granulation, sieve through 30-mesh and 80-mesh sieves, and re-granulate the materials retained on the 30-mesh sieve and the materials passing through the 80-mesh sieve;

[0064] (4) Cold pressing: Automatically perform cold pressing by the constant volume method, and control the cold pressing weight by adjusting the relative position of the punch and the cavity. The granulated powder enters the cavity from the cold press. After the powder is leveled, 4 beads are cold pressed simultaneously at one time. The cold pressing height is 9 mm, the pressure is 300 MPa, and the pressure holding time is 3 s;

[0065] (5) Sintering: Put the beads on an iron matrix, place them on a ceramic plate, and then put them into a vacuum sintering furnace for sintering; the outer diameter of the iron matrix is 5 mm, and the inner diameter of the bead after cold pressing is 0.04 mm larger than the outer diameter of the iron matrix; the sintering temperature is 25 - 450 °C for atmospheric pressure sintering, the heating rate is 3 °C / min. After holding at 450 °C for 30 min, start to evacuate, and keep the vacuum degree at 1×10 -2 MPa, then heat up. The heating rate is 3 °C / min during the process of 450 °C - 800 °C, and the heating rate is 1 °C / min from 800 °C to the final sintering temperature. The final sintering temperature is 950 °C, and the holding time at the final sintering temperature is 1 h. Then cool down at a rate of 4 °C / min to 600 °C, and then cool down to room temperature naturally with the furnace.

[0066] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing beaded products, characterized in that, It includes the following steps: (1) Batching: Calculate the required powder according to the specifications and quantity of the beaded products to be produced, and batch the materials according to the mass percentages of 65-80% of pressureless sintered powder, 10-30% of superfine iron powder, and 5-15% of WC; the pressureless sintered powder includes the following components by weight percentage: 76-77% of Fe, 12-13% of Cu, 7-8% of Ni, 1.8-2.2% of P, and 0.9-1.2% of V; The pressureless sintered powder is produced by sintering using the water-vapor combined atomization method. Select powders with a particle size of 2000-3000 mesh, sinter and hold the powders at 600-700°C in air for 2 h, then introduce nitrogen to replace the air in the furnace, and then introduce H2 or ammonia decomposition gas to keep the powders at a reduced pressure for another 1 h to produce a pressureless sintered powder that meets the performance requirements; (2) Mixing: Put the sintered pressureless sintered powder into a three-dimensional mixer for mixing, then add diamond and granulating agent and mix again; the particle size of the diamond is 35#-60#, and the addition amount is 2-3.5% of the total mass of the powder. The granulating agent is acrylic resin, and the addition amount of the granulating agent is 2-5% of the total mass of the powder; (3) Granulation: Pour the mixed materials into a granulator for granulation after mixing; (4) Cold pressing: Cold press the granulated powder materials using an automatic press to obtain beaded products; (5) Sintering: The beads are put into the matrix and then placed together in a vacuum furnace for sintering to obtain the beads. The sintering method is as follows: The beads are put on the iron matrix, placed on a ceramic plate, and then put into a vacuum sintering machine for sintering; The sintering temperature is 25~450°C for atmospheric pressure sintering, the heating rate is 3~5°C / min, after holding at 450°C for 30 min, vacuum pumping starts, and the vacuum degree is maintained at 1×10 -3 ~10 - 2 MPa, then heat up. During the process of 450°C~800°C, the heating rate is 1.5~3°C / min, and from 800°C to the final sintering temperature, the heating rate is 0.5~1°C / min. The final sintering temperature is 810~950°C, the holding time at the final sintering temperature is 1 h, and then it is cooled to 600°C at a rate of 3~5°C / min, and then naturally cooled to room temperature in the furnace.

2. The preparation method of the beaded products according to claim 1, wherein, The granulation method in step (3) is as follows: Pour the mixed materials into a granulator, set the rotation speed of the granulator at 800-1500 r / min, the granulation time is 2-15 min. After granulation, pass through 30-mesh and 80-mesh sieves, and granulate the materials on the 30-mesh sieve and the materials below the 80-mesh sieve again.

3. The preparation method of the beaded product according to claim 1, wherein The cold pressing in step (4) is carried out by the constant volume method for automatic cold pressing. Control the cold pressing weight by adjusting the relative positions of the punch and the cavity. The granulated powder materials enter the cavity from the cold press. After the powder materials are leveled, cold press 4-16 beaded products simultaneously at one time. The cold pressing height is 6-9 mm, the pressure is 300-600 MPa, and the pressure holding time is 2-3 s.

4. The preparation method of the beaded product according to claim 1, characterized in that The matrix in step (5) is an iron matrix, the outer diameter of the iron matrix is 5-8 mm, and the inner diameter of the beaded product after cold pressing is 0.01-0.04 mm larger than the outer diameter of the iron matrix.

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