Cold pressing die for achieving different concentration distribution of radial abrasive particles in beaded beads and method for cold pressing beads using the die

Abstract

This invention discloses a cold-pressing mold for achieving different concentrations of radial abrasive particles in beaded wire and a method for cold-pressing beads using this mold. The cold-pressing mold includes an upper pressure head assembly, a pre-pressing sleeve, a die, and a lower pressure head assembly. The lower pressure head assembly includes a lower pressure head sleeve and a lower positioning core. The lower positioning core includes a lower core rod base and a lower pressure head core rod fixed thereto. The lower pressure head core rod passes through a lower longitudinal through-hole in the lower pressure head sleeve from bottom to top. A positioning post is provided at the center of the top of the lower pressure head core rod, which is positioned to mate with a through-hole in the bead substrate. The diameter of the positioning post is smaller than the diameter of the lower pressure head core rod, and the two are connected by a conical surface. The diameter of the positioning post matches the inner diameter of the upper longitudinal through-hole. Using the cold-pressing mold of this invention, a beaded cold-pressed blank with a gradually increasing abrasive particle concentration in the radial direction of the bead can be produced, avoiding the simultaneous decrease of abrasive particles as the substrate diameter wears down, thus preventing accelerated wear of the beads in later stages of use.

Description

Technical Field

[0001] This invention relates to diamond wire saws, and more specifically to a cold pressing mold for achieving different concentrations of radial abrasive grains in a beaded string and a method for cold pressing beads using the mold. Background Technology

[0002] Currently, diamond wire saws are being used more and more widely in the stone processing and building cutting industries, and the demand for diamond wire saws is also increasing. According to incomplete statistics, the annual output of wire saws by domestic manufacturers in China alone has exceeded 25 million meters, and it is still growing rapidly.

[0003] A crucial step in the production of diamond wire saws is the pressing and molding of powder containing abrasive particles (diamond grains). Specifically, various metal powders (such as iron powder, cobalt powder, copper powder, etc.) of different weights are thoroughly mixed with the abrasive particles (diamond grains) and then cold-pressed together with a metal matrix in a mold to form beads. Current cold-pressing methods generally employ unidirectional pressing, which easily leads to inconsistent density in the beads, resulting in poor performance. Due to differences in particle size and physical properties between the abrasive particles and metal powder, variations in abrasive particle concentration are unavoidable during mixing and cold pressing. These variations in diamond abrasive particle distribution significantly impact the wire saw's performance. A higher concentration of diamond abrasive particles in the outer layer of the beads in the radial direction leads to lower cutting efficiency; in severe cases, the diamonds may be polished and worn down under high-speed friction, losing their cutting ability. Conversely, a lower concentration of diamond particles in the inner layer of the beads in the radial direction causes the metal matrix to wear away quickly, accelerating uneven wear and ultimately leading to wire rope breakage.

[0004] Existing technologies address the problem of premature wire saw failure due to uneven wear by gradually increasing the abrasive grains from the outside to the inside in the radial direction of the beads. For example, utility model patent CN 211104854U discloses an anti-uneven wear wire saw bead system, comprising a steel body and a matrix working layer. The matrix working layer extends beyond the steel body, and from the steel body outwards, it consists of a guide layer and a first matrix working layer. After hot pressing and sintering, a transition layer is formed at the interface between the two layers. The diamond wheel concentration in the guide layer is greater than that in the first matrix working layer. During operation, signs of uneven wear appearing in the first matrix working layer are gradually alleviated and corrected after entering the guide layer due to its high wear resistance. This restores the wear of the matrix working layer to a normal state, effectively preventing premature wire saw failure due to uneven wear, ensuring the wire saw's service life, improving cost-effectiveness, and saving resources.

[0005] On the other hand, existing traditional cold pressing molds mainly include an upper pressure head 1, a lower pressure head 2, a pre-pressing sleeve 3, a mandrel 4, and a die 5. The upper pressure head 1 and the lower pressure head 2 are inserted into the die 5 from the upper and lower ends, respectively. The mandrel 4 and the lower pressure head 2 limit the upper and lower ends of the bead base 6, respectively. The function of the pre-pressing sleeve 3 is to flatten the powder 7 (the pre-pressing sleeve 3 is removed after the surface of the powder 7 is flattened). When the upper pressure head 1 presses down on the powder 7, the mandrel 4 slides into the core hole opened at the bottom of the upper pressure head 1, as shown in the attached figure. Figure 1 As shown in (a, b, c, d), the abrasive grains in the cold-pressed bead blank produced by this traditional cold-pressing mold are basically uniformly distributed in the radial direction, which cannot meet the requirement that the abrasive grain concentration gradually increases from the outside to the inside in the radial direction. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a cold pressing mold that can achieve different concentration distributions of abrasive particles in the radial direction of the beads by gradually increasing the abrasive particle concentration from the outside to the inside, and a method for cold pressing beads using the mold.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A cold pressing die for achieving different concentration distributions of radial abrasive particles in a beaded assembly includes an upper pressure head assembly, a pre-pressure sleeve, a die cavity, and a lower pressure head assembly. The upper pressure head assembly and the lower pressure head assembly are inserted into the die cavity from the upper and lower ends, respectively.

[0009] The upper pressure head assembly includes an upper pressure head sleeve and an upper positioning core. The upper positioning core includes an upper core rod base and an upper pressure head core rod that is longitudinally fixed to the upper core rod base. The upper pressure head core rod passes through the upper longitudinal through hole opened in the upper pressure head sleeve from top to bottom.

[0010] The lower pressure head assembly includes a lower pressure head sleeve and a lower positioning core. The lower positioning core includes a lower core rod base and a lower pressure head core rod that is longitudinally fixed to the lower core rod base. The lower pressure head core rod passes through the lower longitudinal through hole opened in the lower pressure head sleeve from bottom to top.

[0011] The diameter of the lower pressure head core rod matches the inner diameter of the lower longitudinal through hole. A positioning post is provided at the middle of the top of the lower pressure head core rod to cooperate with the through hole of the bead base for positioning. The diameter of the positioning post is smaller than the diameter of the lower pressure head core rod, and the two are connected by a conical surface. The diameter of the positioning post matches the inner diameter of the upper longitudinal through hole.

[0012] In the aforementioned cold-pressing mold technical solution, a through hole is formed in the pre-pressing sleeve, and the inner diameter of the through hole matches the diameter of the positioning pin. When the powder is pre-pressed (flattened or compacted) using the pre-pressing sleeve, the positioning pin will insert into or even protrude from the through hole in the pre-pressing sleeve. The pre-pressing sleeve is usually made of elastic material so that it can smoothly extend into the conical surface connecting the positioning pin and the lower pressure head core rod when pressing downwards.

[0013] In the above-mentioned cold pressing mold technical solution, the diameter of the positioning post matches the inner diameter of the bead base, and the diameter of the lower pressing head core rod matches the outer diameter of the bead base. In this way, when the lower pressing head core rod is withdrawn, the bead base on the positioning post can just enter the inner hole of the pre-pressed powder.

[0014] The applicant discovered in the experiment that the taper of the conical surface connecting the positioning post and the lower pressure head core rod affects the direction of abrasive movement during the extrusion process. When the taper is too large, the abrasive mainly moves along the axial direction, and when the taper is too small, the abrasive mainly moves along the radial direction. The preferred taper of the conical surface connecting the positioning post and the lower pressure head core rod in this application is 1:5 to 1:8.

[0015] To further limit the positioning of the beaded substrate, an annular groove can be opened at the bottom of the upper pressure head sleeve. When the upper pressure head sleeve is fitted onto the positioning post and moves downward a certain distance, the top of the beaded substrate fitted onto the positioning post pushes into the annular groove at the bottom of the upper pressure head sleeve.

[0016] This invention also provides a method for producing a cold-pressed bead blank with the abrasive concentration gradually increasing from the outside to the inside in the radial direction of the beads using the above-mentioned cold-pressing mold, comprising the following steps:

[0017] 1) Select the bead base and its formulation according to the required specifications of the beads, weigh the appropriate amount of components and mix them evenly to obtain powder;

[0018] 2) Fill the molding cavity formed by the die and the lower pressure head assembly with powder, insert the pre-pressure sleeve into the die so that the positioning pin enters the through hole on the pre-pressure sleeve, apply pressure to the pre-pressure sleeve to perform the first pre-press molding of the powder; then fix the pre-pressure sleeve and push the lower positioning core to move upward to perform the second pre-press molding of the powder until the powder is completely wrapped around the lower pressure head core rod and the positioning pin extends out of the die;

[0019] 3) Remove the pre-press sleeve, put the beaded substrate on the positioning post, and then put the upper pressure head assembly on the positioning post, wherein the positioning post extends into the upper longitudinal through hole of the upper pressure head sleeve. Push the upper pressure head assembly downward until the bottom end of the upper pressure head sleeve contacts the top of the powder, and the beaded substrate has entered the inner hole of the pre-pressed powder. At this time, maintain this state, apply a certain pressure, and hold the pressure for a certain time for cold pressing and molding. Demold to obtain a beaded cold-pressed blank in which the abrasive concentration gradually increases from the outside to the inside in the radial direction.

[0020] The processes not mentioned in the above steps are the same as those in the existing technology. For example, when performing cold pressing, the applied pressure is usually 500~1000 MPa, and the holding time is usually 10~15 seconds.

[0021] Compared with the prior art, the present invention is characterized by:

[0022] 1. Based on the existing cold pressing equipment, the concentration of diamond abrasive particles in the inner layer of the tire is changed by improving the structure of the lower pressure head. Specifically, a diameter difference is designed between the positioning column and the lower pressure head core rod. The positioning column has a smaller diameter, while the lower pressure head core rod has a larger diameter. The powder is first pre-pressed at the smaller diameter of the positioning column. Then, under the action of the larger diameter of the lower pressure head core rod, the powder that was pre-pressed once is squeezed and moved from the inside to the outside in the diameter direction for a second pre-pressing. This increases the powder density in the area near the lower pressure head core rod, and at the same time, the abrasive particle concentration in this area is also relatively increased.

[0023] 2. The abrasive concentration gradually increases from the outer layer to the inner layer of the tire body to ensure that the number of abrasive particles exposed on the surface is relatively consistent when the tire body wears down to different diameters. This avoids the abrasive particles decreasing simultaneously as the tire body diameter wears down, which would exacerbate the wear of the beads in the later stages of use, and even lead to the problem of uneven wear of the tire body in the later stages of use, causing the base material to be scrapped prematurely.

[0024] 3. When using the method described in this invention to produce beaded cold-pressed blanks, the powder does not need to be granulated and can be used directly, making the process simple and efficient. Attached Figure Description

[0025] Figure 1 The diagram shows the structure of an existing traditional cold pressing mold; (a) is a structural diagram of the existing traditional cold pressing mold when the powder is flattened by a pre-pressing sleeve, (b) is a structural diagram of the existing traditional cold pressing mold after pressing, (c) is a structural diagram of the beads after the beads of the cold pressing blank pressed by the existing traditional cold pressing mold are sintered, and (d) is a top view of (c).

[0026] Figure 2 This is a schematic diagram of the cold-pressing mold for achieving radially different concentration distributions of beads as described in this invention.

[0027] Figure 3 This is a schematic diagram of the structure when powder is added in Embodiment 3 of the present invention.

[0028] Figure 4 This is a schematic diagram of the structure when the powder is pre-compressed once using a pre-compressing sleeve in Embodiment 3 of the present invention.

[0029] Figure 5 This is a schematic diagram of the structure in Embodiment 3 of the present invention, in which the positioning core is pushed upward to perform secondary pre-compression of the powder.

[0030] Figure 6 This is a schematic diagram of the structure in Embodiment 3 of the present invention, in which the beaded substrate is placed on the positioning post after the pre-pressing sleeve is removed, and the upper pressing head assembly is placed on the positioning post with the positioning post extending into the upper longitudinal through hole of the upper pressing head sleeve.

[0031] Figure 7This is a schematic diagram of the structure in Embodiment 3 of the present invention, in which the upper pressure head assembly is pushed downward until the top of the beaded substrate is inserted into the annular groove at the bottom of the upper pressure head sleeve and the bottom of the upper pressure head sleeve contacts the top of the powder, while the beaded substrate has entered the inner hole of the pre-pressed powder.

[0032] Figure 8 The diagram shows the structure of the beads produced in Embodiment 3 of the present invention; wherein, (a) is the front view of the cold-pressed sintered beads, and (b) is the top view of (a).

[0033] The numbers on the map are:

[0034] 1 Upper pressure head, 2 Lower pressure head, 3 Pre-pressure sleeve, 4 Mandrel, 5 Die, 6 Beaded base, 7 Powder, 8 Upper pressure head sleeve, 9 Upper positioning core, 901 Upper pressure head core rod, 902 Upper core rod base, 10 Lower pressure head sleeve, 11 Lower positioning core, 1101 Lower pressure head core rod, 1102 Lower core rod base, 1103 Positioning pin. Detailed Implementation

[0035] To better explain the technical solution of the present invention, the present invention will be described in further detail below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0036] Example 1: Cold pressing mold for achieving radial concentration distribution of beads

[0037] like Figure 2 As shown, the cold pressing mold for achieving radially different concentration distributions of beads according to the present invention includes an upper pressing head assembly, a pre-pressing sleeve 3, a concave mold 5, and a lower pressing head assembly. The upper pressing head assembly and the lower pressing head assembly are respectively inserted into the concave mold 5 from the upper and lower ends to define the upper and lower ends of the bead base 6. The upper pressing head assembly, the concave mold 5, and the lower pressing head assembly form a forming cavity for pressing the cold-pressed bead blank.

[0038] To obtain a beaded cold-pressed blank with a gradually increasing abrasive concentration from the outside to the inside in the radial direction, this invention improves the upper pressure head of the traditional mold into an upper pressure head assembly structure, and the lower pressure head into a lower pressure head assembly structure, as detailed below:

[0039] The upper pressure head assembly includes an upper pressure head sleeve 8 and an upper positioning core 9. The upper positioning core 9 includes an upper core rod base 902 and an upper pressure head core rod 901 longitudinally fixed to the upper core rod base 902. The upper pressure head core rod 901 passes through the upper longitudinal through hole opened in the upper pressure head sleeve 8 from top to bottom.

[0040] The lower pressure head assembly includes a lower pressure head sleeve 10 and a lower positioning core 11. The lower positioning core 11 includes a lower core rod base 1102 and a lower pressure head core rod 1101 longitudinally fixed to the lower core rod base 1102. The lower pressure head core rod 1101 passes through a lower longitudinal through hole opened in the lower pressure head sleeve 10 from bottom to top. The diameter of the lower pressure head core rod 1101 matches the inner diameter of the lower longitudinal through hole. A positioning post 1103 is provided at the middle of the top of the lower pressure head core rod 1101 to cooperate with the through hole of the bead base 6 for positioning. The diameter of the positioning post 1103 is smaller than the diameter of the lower pressure head core rod 1101, and the two are connected by a conical surface. The diameter of the positioning post 1103 matches the inner diameter of the upper longitudinal through hole.

[0041] The positioning post 1103 and the lower pressure head core rod 1101 are designed with a diameter difference. The positioning post 1103 has a smaller diameter and the lower pressure head core rod 1101 has a larger diameter. The powder 7 is first pre-pressed at the smaller diameter of the positioning post 1103. Then, under the action of the larger diameter of the lower pressure head core rod 1101, the powder 7 pre-pressed once is squeezed and moved from the inside to the outside in the diameter direction for a second pre-pressing. This increases the density of the powder 7 in the area near the lower pressure head core rod 1101, and at the same time, the abrasive concentration in this area is also relatively increased.

[0042] The pre-compression sleeve 3 has a through hole penetrating its body, the inner diameter of which matches the diameter of the positioning post 1103. When the powder 7 is pre-compressed (flattened or compacted) using the pre-compression sleeve 3, the positioning post 1103 will insert into or even protrude from the through hole on the pre-compression sleeve 3. The pre-compression sleeve 3 is usually made of an elastic material so that it can smoothly extend into the conical surface connecting the positioning post 1103 and the lower pressure head core rod 1101 when pressed downwards.

[0043] The diameter of the positioning post 1103 matches the inner diameter of the bead base 6, and the diameter of the pressing head core rod 1101 matches the outer diameter of the bead base 6. Thus, when the pressing head core rod 1101 is withdrawn, the bead base 6 on the positioning post 1103 can just enter the inner hole of the pre-pressed powder 7.

[0044] In the above-mentioned technical solution for cold pressing mold, the taper of the tapered surface connecting the positioning post 1103 and the lower pressure head core rod 1101 is preferably 1:5 to 1:8.

[0045] In one specific embodiment, an annular groove is formed at the bottom end of the upper pressure head sleeve 8. After the upper pressure head sleeve 8 is fitted onto the positioning post 1103 and moves downward a certain distance, the top end of the bead base 6 fitted onto the positioning post 1103 pushes into the annular groove at the bottom end of the upper pressure head sleeve 8 to further limit the bead base 6.

[0046] Example 2: Method for producing a cold-pressed beaded blank

[0047] The method for producing a cold-pressed beaded blank with a gradually increasing abrasive concentration from the outside to the inside in the radial direction of the beads using the cold-pressing mold described in Example 1 includes the following steps:

[0048] 1) Select the bead base 6 and its matrix formula according to the specifications of the beads to be made, weigh the appropriate amount of components and mix them evenly to obtain powder 7;

[0049] 2) Powder 7 is put into the molding cavity formed by the die 5 and the lower pressure head assembly. The pre-press sleeve 3 is inserted into the die 5 so that the positioning pin 1103 enters the through hole on the pre-press sleeve 3. Pressure is applied to the pre-press sleeve 3 to perform the first pre-press molding of powder 7. Then the pre-press sleeve 3 is fixed and the lower positioning core 11 is pushed to move upward to perform the second pre-press molding of powder 7 until the powder 7 is completely wrapped around the lower pressure head core rod 1101 and the top of the positioning pin 1103 extends out of the die 5.

[0050] 3) Remove the pre-press sleeve 3, put the beaded substrate 6 on the positioning post 1103, and then put the upper pressure head assembly on the positioning post 1103, wherein the positioning post 1103 extends into the upper longitudinal through hole of the upper pressure head sleeve 8, push the upper pressure head assembly downward until the bottom end of the upper pressure head sleeve 8 contacts the top end of the powder 7, and the beaded substrate 6 has entered the inner hole of the pre-pressed powder 7. At this time, maintain this state, apply a certain pressure and hold the pressure for a certain time for cold pressing, demold, and obtain a beaded cold-pressed blank in which the abrasive concentration gradually increases from the outside to the inside in the radial direction.

[0051] The processes not mentioned in the above steps are the same as those in the existing technology. For example, when performing cold pressing, the applied pressure is usually 500~800 MPa and the holding time is usually 10~15 seconds.

[0052] Example 3: Fabrication of beads with a diameter of Ø7.0~7.5mm and an abrasive concentration that gradually increases from the outside to the inside in the radial direction of the beads.

[0053] 1) The cold-pressed blank with a diameter of Ø7.0~7.5mm and an abrasive concentration that gradually increases from the outside to the inside in the radial direction of the beads is produced using the cold-pressing mold described in Example 1, including the following steps:

[0054] 1.1) Select the bead base 6 and its matrix formula according to the specifications of the beads to be made, weigh the appropriate amount of components and mix them evenly to obtain powder 7.

[0055] The main element selected is FeCoCu pre-alloyed powder, with a theoretical density of approximately 8.78 g / cm³. The bead matrix 6 is a 45# steel cylinder, 11.3 mm in length, 4.8 mm in outer diameter, and 3.5 mm in inner diameter. The diamond particle size is 45 / 50 (particle size Ø0.3~0.36 mm).

[0056] The dimensions of the cold pressing mold are determined according to the size of the beads to be made: the outer diameter of the upper pressure head sleeve is Ø7.5(h8)mm (h8 indicates that it is machined according to grade 8 shaft tolerance, the same below), and the inner diameter is Ø4.8(H7)mm (H7 indicates that it is machined according to grade 7 hole tolerance, the same below); the outer diameter of the upper pressure head core rod 901 is Ø4.8(h8)mm; the outer diameter of the pre-pressure sleeve 3 is Ø7.5(h8)mm; the inner diameter of the pre-pressure sleeve 3 is Ø3.5(H7)mm; the inner diameter of the die 5 is Ø7.5(H7)mm; the outer diameter of the lower pressure head sleeve 10 is Ø7.5(h8)mm, and the inner diameter is Ø4.8(H7)mm; the diameter of the lower pressure head core rod 1101 is Ø4.8(h8)mm; and the diameter of the positioning pin 1103 is Ø3.5(h8)mm in the middle.

[0057] Based on the density of the selected metal powder, the total diamond concentration, and the matrix design dimensions, 1.37g of FeCoCu pre-alloyed powder and 0.02g of diamond were weighed and mixed evenly to obtain 1.39±0.05g of powder 7.

[0058] 1.2) The weighed mixed powder 7 is put into the molding cavity formed by the die 5 and the pressing head assembly (e.g., Figure 3 As shown), the pre-compression sleeve 3 is inserted into the die 5 so that the positioning pin 1103 enters the through hole on the pre-compression sleeve 3. Pressure is applied to the pre-compression sleeve 3 to perform a pre-compression molding of the powder 7 (as shown). Figure 4 (as shown); then fix the pre-compression sleeve 3, and push the lower positioning core 11 to move upward to perform secondary pre-compression molding of the powder 7 (as shown). Figure 5 As shown), until the powder 7 is completely surrounded on the lower pressure head core rod 1101 and the top of the positioning post 1103 extends out of the die 5.

[0059] 1.3) Remove the pre-compression sleeve 3, place the beaded base 6 onto the positioning post 1103, and then place the upper pressure head assembly onto the positioning post 1103, wherein the positioning post 1103 extends into the upper longitudinal through hole of the upper pressure head sleeve 8 (e.g., Figure 6 As shown), the upper pressure head assembly is pushed downwards until the top of the beaded base 6 is inserted into the annular groove at the bottom of the upper pressure head sleeve 8 and the bottom of the upper pressure head sleeve 8 contacts the top of the powder 7. At the same time, the beaded base 6 has entered the inner hole of the pre-pressed powder 7 (as shown). Figure 7 As shown), this state is maintained at 500 MPa pressure for 10 seconds, and powder 7 is cold-pressed to a height of 9.5 mm. After demolding, a beaded cold-pressed blank with diamond concentration gradually increasing from the outside to the inside in the radial direction is obtained.

[0060] 2) The obtained cold-pressed bead blank is installed in a sintered graphite negative mold. Under the action of the upper and lower sintering heads, hot pressing sintering is carried out according to the sintering process recommended by the powder manufacturer (sintering temperature 900℃, holding time 5 minutes, holding pressure 300Mpa) to sinter the height of the cold-pressed blank from 9.5mm to 6.5mm, thus obtaining cold-pressed sintered beads.

[0061] 3) The resulting cold-pressed sintered beads are then ground with a grinding wheel to sharpen the surface of the matrix, exposing the outermost diamond layer. This yields beads used for making wire saws where the abrasive concentration gradually increases from the outside to the inside in the radial direction of the beads (e.g., ...). Figure 8 (As shown). The parts not detailed herein are the same as those in the prior art.

Claims

1. A cold pressing die for achieving different concentration distributions of radial abrasive particles in a beaded assembly, comprising an upper pressure head assembly, a pre-pressure sleeve (3), a die cavity (5), and a lower pressure head assembly, wherein the upper pressure head assembly and the lower pressure head assembly are inserted into the die cavity (5) from the upper and lower ends, respectively, characterized in that, The upper pressure head assembly includes an upper pressure head sleeve (8) and an upper positioning core (9). The upper positioning core (9) includes an upper core rod base (902) and an upper pressure head core rod (901) longitudinally fixed to the upper core rod base (902). The upper pressure head core rod (901) passes through the upper longitudinal through hole opened in the upper pressure head sleeve (8) from top to bottom. The lower pressure head assembly includes a lower pressure head sleeve (10) and a lower positioning core (11). The lower positioning core (11) includes a lower core rod base (1102) and a lower pressure head core rod (1101) longitudinally fixed to the lower core rod base (1102). The lower pressure head core rod (1101) passes through the lower longitudinal through hole opened in the lower pressure head sleeve (10) from bottom to top. The diameter of the lower pressure head core rod (1101) matches the inner diameter of the lower longitudinal through hole. A positioning post (1103) is provided at the middle of the top of the lower pressure head core rod (1101) to cooperate with the through hole of the bead base (6) for positioning. The diameter of the positioning post (1103) is smaller than the diameter of the lower pressure head core rod (1101), and the two are connected by a conical surface. The diameter of the positioning post (1103) matches the inner diameter of the upper longitudinal through hole. The diameter of the positioning post (1103) matches the inner diameter of the bead base (6), and the diameter of the lower pressure head core rod (1101) matches the outer diameter of the bead base (6). The inner diameter of the through hole opened on the preload sleeve (3) matches the diameter of the positioning post (1103).

2. The cold pressing die for achieving different concentration distributions of radial abrasive particles in beads according to claim 1, characterized in that, The taper of the tapered surface connecting the positioning post (1103) and the lower pressure head core rod (1101) is 1:5 to 1:

8.

3. A method for producing a cold-pressed beaded blank with a gradually increasing abrasive particle concentration from the outside to the inside in the radial direction of the beads using the cold-pressing mold as described in claim 1, characterized in that, Includes the following steps: 1) Weigh out the appropriate amount of each component according to the required specifications of the beads and the formula of the base material, and mix them evenly to obtain powder (7); 2) Fill the molding cavity formed by the die (5) and the lower pressure head assembly with powder (7), insert the pre-press sleeve (3) into the die (5) so that the positioning pin (1103) enters the through hole on the pre-press sleeve (3), apply pressure to the pre-press sleeve (3) to perform a first pre-press molding of the powder (7); then fix the pre-press sleeve (3), push the lower positioning core (11) to move upward to perform a second pre-press molding of the powder (7) until the powder (7) is completely wrapped around the lower pressure head core rod (1101) and the positioning pin (1103) extends out of the die (5); 3) Remove the pre-press sleeve (3), put the beaded substrate (6) on the positioning post (1103), and then put the upper pressure head assembly on the positioning post (1103), wherein the positioning post (1103) extends into the upper longitudinal through hole of the upper pressure head sleeve (8), push the upper pressure head assembly downward until the bottom end of the upper pressure head sleeve (8) contacts the top end of the powder (7), and the beaded substrate (6) has entered the inner hole of the pre-pressed powder (7). At this time, maintain this state, apply a certain pressure and hold the pressure for a certain time to perform cold pressing, demold, and obtain a beaded cold pressing blank in which the abrasive concentration gradually increases from the outside to the inside in the radial direction.

4. The method according to claim 3, characterized in that, In step 3), the applied pressure is 500~1000 MPa.

5. The method according to claim 3, characterized in that, In step 3), the pressure holding time is 10~15s.

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