Preparation process and preparation system based on silicon nitride ceramic bearing ball

Abstract

The invention discloses a preparation process and a preparation system based on silicon nitride ceramic bearing balls, and relates to the technical field of silicon nitride ceramic bearing balls, the preparation process comprises the following steps: S1, raw material mixing: mixing high-purity silicon nitride powder, a sintering aid and a flexibilizer by wet ball milling to obtain a mixture A; s2, dry pressing forming: performing extrusion forming on the mixture A so as to enable the mixture A to form a biscuit; and S3, air pressure sintering: in a nitrogen atmosphere, rapidly heating the biscuit to 1800 DEG C, preserving heat for 15-35 minutes, then cooling to 1600 DEG C, and preserving heat for more than 8 hours to inhibit grain growth so as to obtain a fine grain structure. According to the silicon nitride ceramic bearing ball, the density distribution in the silicon nitride ceramic bearing ball can be effectively improved, the silicon nitride ceramic bearing ball is more stable during high-speed rotation through uniform density, the unbalance phenomenon is reduced, and the stability of the bearing during high-speed rotation is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon nitride ceramic bearing balls, and specifically to a preparation process and a preparation system for silicon nitride ceramic bearing balls. Background Art

[0002] Silicon nitride ceramic bearing balls are high-performance bearing components made of silicon nitride, which have the characteristics of high hardness, high wear resistance, high temperature resistance, corrosion resistance, etc. At present, when preparing, high-purity and uniform-particle-size silicon nitride ceramic powder is used, and extrusion molding is carried out by using a molding die to ensure the dimensional accuracy and uniformity of the product. High-temperature and high-pressure sintering technology is carried out to form high-density composite silicon nitride ball bearing balls.

[0003] The current preparation process of silicon nitride ceramic bearing balls faces the following problems. When the particle size distribution of the raw materials is uneven, the voids between small particles may not be effectively filled by large particles, and more pores are likely to remain during the sintering process, resulting in insufficient density of the sintered ceramic balls, which will seriously affect the mechanical properties of silicon nitride ceramic bearing balls, leading to a decrease in their hardness, wear resistance, and an imbalance problem during high-speed rotation. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation process and a preparation system for silicon nitride ceramic bearing balls to solve the deficiencies in the above-mentioned prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A preparation process for silicon nitride ceramic bearing balls, including the following steps:

[0006] S1, raw material mixing: Wet ball milling is used to mix high-purity silicon nitride powder, sintering aids, and toughening agents to obtain mixture A;

[0007] S2, dry pressing forming: Extrusion molding is carried out on mixture A so that mixture A forms a green body;

[0008] S3, gas pressure sintering: In a nitrogen atmosphere, the green body is rapidly heated to 1800 °C, held for 15 - 35 min, and then cooled to 1600 °C and held for more than 8 hours to inhibit grain growth and obtain a fine-grained structure;

[0009] S4, precision machining: Coarse grinding is carried out using a diamond grinding wheel, and then fine polishing is carried out using chemical mechanical polishing or magnetorheological polishing so that the surface roughness Ra ≤ 0.01 μm.

[0010] Preferably, the sintering aids adopt the Y 2 O 3 -MgO system, and its addition ratio is 5 - 10 wt%.

[0011] Preferably, in S2, the forming pressure required for the green body is 200-300 MPa.

[0012] Preferably, the toughening agent is silicon carbide whiskers, and its addition ratio is 2-5 wt.%.

[0013] A preparation system for silicon nitride ceramic bearing balls, comprising:

[0014] A vertical frame;

[0015] A mold assembly, which includes a material placement frame, a chute, and a forming block. A plurality of the chutes are respectively opened at the upper and lower bottom surfaces of the material placement frame. The forming block is slidably connected to the chute. A forming cavity is opened on the forming block. A pair of the forming cavities are spliced to form a first semi-circular cavity. The mold assembly has a first position and a second position;

[0016] A sliding block, which is slidably connected to the vertical frame, and the material placement frame is rotatably connected to the sliding block;

[0017] A first elastic member, which applies an upward thrust to the sliding block;

[0018] A pressure assembly, including a fixed disk and a punch. The punch is fixedly installed on the fixed disk. A second semi-circular cavity is opened at the lower part of the punch. The first semi-circular cavity and the second semi-circular cavity can be spliced to form a complete spherical cavity;

[0019] A power unit, which is used to drive the mold assembly to move from the first position to the second position. During this stroke, under the drive of the power unit, the pressure assembly moves downward, the punch inserts into the first semi-circular cavity, and the mold assembly is displaced to the second position under pressure. The mixture A in the cavity is extruded by the punch to form a green body;

[0020] A discharging part. After the power unit moves upward, under the elastic force of the first elastic member, the mold assembly will reset from the second position to the first position. During this stroke, the discharging part passively drives the mold assembly to rotate so that the green body at the lower bottom surface of the material placement frame is separated.

[0021] Preferably, guide grooves are opened on both sides of the material placement frame, guide columns are rotatably connected to both sides of the forming block, and the guide columns are rollingly connected in the guide grooves.

[0022] Preferably, a central shaft is provided on the material placement frame, and the central shaft is rotatably connected to the sliding block.

[0023] Preferably, the discharging part includes a flipping assembly and a triggering assembly. The flipping assembly includes a force arm and a rotating roller. The middle part of the force arm is fixedly installed at the end of the central shaft. A pair of the rotating rollers are respectively rotatably connected to both ends of the force arm. The triggering assembly includes a triggering block, a second elastic member, and an auxiliary plate. The triggering block is slidably connected to the auxiliary plate, and the second elastic member applies a thrust force to the triggering block towards the direction where the flipping assembly is located.

[0024] Preferably, a slope is provided at one end of the triggering block close to the flipping assembly. When the mold assembly moves from the second position to the first position for resetting, the rotating roller abuts against the slope, and the slope will hinder the upward movement of the force arm, so that the force arm drives the material placing frame to rotate.

[0025] Preferably, it includes a first positioning shaft and a second positioning shaft. The first positioning shaft is installed at the lower part of the vertical frame, and the second positioning shaft is installed at the upper part of the vertical frame. Through holes adapted to the first positioning shaft and the second positioning shaft are provided on both the sliding block and the central shaft.

[0026] In the above technical solution, a preparation process of silicon nitride ceramic bearing balls provided by the present invention can effectively improve the density distribution inside the silicon nitride ceramic bearing balls. Due to the uniform density, the silicon nitride ceramic bearing balls are more stable during high-speed rotation, reducing the imbalance phenomenon and greatly improving the stability of the bearing during high-speed rotation. Moreover, the silicon carbide whiskers play a connecting role inside the silicon nitride ceramic bearing balls, which can greatly increase the connection of internal grains and further increase the stability of the silicon nitride ceramic bearing balls in the high-speed state, reducing the risk of cracking of the silicon nitride ceramic bearing balls. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic diagram of the overall structure of a preparation process and a preparation system of silicon nitride ceramic bearing balls according to the present invention;

[0029] Figure 2 It is a schematic diagram of the structure of the discharging part when the mold assembly of a preparation process and a preparation system of silicon nitride ceramic bearing balls according to the present invention moves from the second position to the first position for resetting;

[0030] Figure 3 It is an attached Figure 2 Schematic diagram of the enlarged structure at A in the present invention;

[0031] Figure 4 Schematic diagram of the structure when the mold assembly of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention is in the first position;

[0032] Figure 5 Schematic diagram of the structure when the mold assembly of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention is in the second position;

[0033] Figure 6 Attachment of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention Figure 5 Enlarged structure diagram at position B;

[0034] Figure 7 Cross-sectional view of the mold assembly of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention;

[0035] Figure 8 Schematic diagram of the cross-sectional view of the mold assembly of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention;

[0036] Figure 9 Attachment of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention Figure 8 Enlarged structure diagram at position C;

[0037] Figure 10 Schematic diagram of the structure of the material placing frame of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention;

[0038] Figure 11 Attachment of a preparation process and a preparation system for silicon nitride ceramic bearing balls according to the present invention Figure 10 Enlarged structure diagram at position D.

[0039] Explanation of reference numerals: 1, material receiving part; 2, vertical frame; 3, sliding block; 4, mold assembly; 41, material placing frame; 42, chute; 421, forming block; 422, forming cavity; 43, guide post; 44, guiding groove; 5, central shaft; 51, first positioning shaft; 52, second positioning shaft; 6, flipping assembly; 61, force arm; 62, rotating roller; 7, triggering assembly; 71, triggering block; 72, second elastic member; 73, auxiliary plate; 8, pressure assembly; 82, fixed disk; 83, punch; 9, first elastic member; 10, power unit. Detailed implementation manners

[0040] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further introduced in detail below in conjunction with the accompanying drawings.

[0041] Please refer to Figure 1-11, A preparation process of silicon nitride ceramic bearing balls provided by an embodiment of the present invention includes the following steps:

[0042] S1, Raw material mixing: Using wet ball milling to mix high-purity silicon nitride powder, sintering aids, and toughening agents to obtain mixture A;

[0043] S2, Dry pressing forming: Extruding and forming mixture A so that mixture A forms a green body;

[0044] S3, Gas pressure sintering: Under a nitrogen atmosphere, quickly heating the green body to 1800 °C, holding for 15 - 35 min, and then cooling to 1600 °C and holding for more than 8 hours to inhibit grain growth and obtain a fine-grained structure;

[0045] S4, Precision machining: Using a diamond grinding wheel for rough grinding, and then using chemical mechanical polishing or magnetorheological polishing for fine polishing so that the surface roughness Ra ≤ 0.01 μm.

[0046] The sintering aids adopt a Y 2 O 3 -MgO system, and its addition ratio is 5 - 10 wt%.

[0047] In S2, the required forming pressure of the green body is 200 - 300 MPa.

[0048] The toughening agent adopts silicon carbide whiskers, and its addition ratio is 2 - 5 wt.%.

[0049] In the embodiment of the present invention: Y 2 O 3 -MgO system refers to a material using yttrium oxide (Y 2 O 3 ) and magnesium oxide (MgO) as additives or main components. Its function is that during the sintering process of silicon nitride ceramics, the Y 2 O 3 -MgO system can form a liquid phase at high temperature. This liquid phase can fill the voids between silicon nitride particles, promote particle rearrangement and diffusion, thereby reducing the sintering temperature and improving the density of the sintered body. For example, when gas pressure sintering silicon nitride ceramics, adding an appropriate amount of Y 2 O 3 and MgO can reduce the sintering temperature from above 1900 °C without additives to about 1700 - 1850 °C. Yttrium oxide (Y 2 O 3)Combined with silicon carbide whiskers and magnesium oxide (MgO), due to its unique microstructure, it can play a bridging and pulling-out role in the silicon nitride ceramic matrix. When the ceramic matrix is subjected to external forces and cracks occur, the silicon carbide whiskers can span across both ends of the crack like a bridge, preventing the crack from further expanding. At the same time, during the crack expansion process, the whiskers will be pulled out from the silicon nitride particles, and this process will consume a large amount of energy, thus effectively improving the toughness of the ceramic ball and reducing the risk of its rupture under high loads;

[0050] Through the above process, the density distribution inside the silicon nitride ceramic bearing ball can be effectively improved. By making the density uniform, the silicon nitride ceramic bearing ball is more stable during high-speed rotation, reducing the unbalance phenomenon and greatly enhancing the stability of the bearing during high-speed rotation. Moreover, due to the connection role of the silicon carbide whiskers inside the silicon nitride ceramic bearing ball, the internal grain connection can be greatly increased, further increasing the stability of the silicon nitride ceramic bearing ball under high-speed conditions and reducing the risk of rupture of the silicon nitride ceramic bearing ball.

[0051] During the forming stage, the mixture A needs to be extruded to form a green body. After sintering the green body, a silicon nitride ceramic bearing ball blank is formed. When forming the green body, the pressure is 200 - 300 MPa. Although a demolding agent is applied in the mold cavity, it is still difficult to take out the green body from the mold. Therefore, we propose a preparation system that can effectively reduce the demolding time of the green body and improve production efficiency.

[0052] A preparation system based on silicon nitride ceramic bearing balls includes a forming device, and the forming device includes:

[0053] A vertical frame 2;

[0054] A mold assembly 4, the mold assembly 4 includes a material placement frame 41, a chute 42, and a forming block 421. A plurality of the chutes 42 are respectively opened at the upper and lower bottom surfaces of the material placement frame 41, the forming block 421 is slidably connected to the chute 42, a forming cavity 422 is opened on the forming block 421, and a pair of the forming cavities 422 are spliced to form a first semi-circular cavity. The mold assembly 4 has a first position and a second position;

[0055] A sliding block 3, the sliding block 3 is slidably connected to the vertical frame 2, and the material placement frame 41 is rotatably connected to the sliding block 3;

[0056] A first elastic member 9, the first elastic member 9 applies an upward thrust to the sliding block 3;

[0057] A pressure assembly 8, including a fixed disk 82 and a punch 83, the punch 83 is fixedly installed on the fixed disk 82, a second semi-circular cavity is opened at the lower part of the punch 83, and the first semi-circular cavity and the second semi-circular cavity can be spliced to form a complete spherical cavity;

[0058] A power unit 10 is used to drive a die assembly 4 to move from a first position to a second position. During this stroke, under the drive of the power unit 10, a pressure assembly 8 moves downward, and a punch 83 is inserted into a first semi-circular cavity. The die assembly 4 is displaced to the second position under pressure, and the mixture A in the cavity is extruded by the punch 83 to form a green body.

[0059] A blank discharging part. After the power unit 10 moves upward, under the elastic force of a first elastic member 9, the die assembly 4 will reset from the second position to the first position. During this stroke, the blank discharging part passively drives the die assembly 4 to rotate so that the green body on the lower bottom surface of a blank placing frame 41 is separated.

[0060] In an embodiment of the present invention, after the mixture A is added into the blank placing frame 41, it is scraped by a scraper to be evenly filled into the first semi-circular cavity formed by a forming cavity 422. After the power unit 10 is started, it drives the pressure assembly 8 to move downward, and the punch 83 corresponds to the first semi-circular cavity, and the punch 83 will be inserted into the first semi-circular cavity. A second semi-circular cavity is formed at the bottom of the punch 83. At this time, as shown in the appendix Figure 9 shown, a complete spherical cavity is formed by splicing the first semi-circular cavity and the second semi-circular cavity. In this way, the mixture A will form a sphere under the extrusion of the punch 83 and a forming block 421 to complete the forming of the green body.

[0061] During the downward movement of the power unit 10, a sliding block 3 will move downward synchronously against the elastic force of the first elastic member 9. At this time, the first elastic member 9 is compressed until the die assembly 4 moves to the second position. At the second position, the die assembly 4 reaches the lowest point. At this time, under pressure, the mixture A has formed a green body.

[0062] After the green body is formed, the power unit 10 quickly retracts, and the punch 83 will also disengage from the die assembly 4. After losing the pressure of the power unit 10, the first elastic member 9 will drive the sliding block 3 to move upward. When the sliding block 3 moves upward, it synchronously drives the die assembly 4 to move upward. The die assembly 4 will reset from the second position to the first position. During this process, the blank discharging part will passively drive the die assembly 4 to rotate. Since the die assembly 4 is flipped 180 degrees, under the action of gravity, the forming block 421 will slide and unfold along a chute 42. In this way, the formed green body will be separated from the die assembly 4, and the blank discharging is convenient and fast. When reset to the first position, the addition of the mixture A can be carried out immediately, and the production continuity is good, significantly improving the production efficiency.

[0063] Furthermore, due to the relatively large extrusion pressure of the green body, even after being flipped 180 degrees, it is difficult for some of the forming blocks 421 to unfold solely by the action of gravity. Therefore, in the present invention, the rebound of the first elastic member 9 drives the sliding block 3 to impact the upper part of the vertical frame 2. The vibration generated during the impact can greatly promote the unfolding of the forming blocks 421, greatly reducing the phenomenon of green body jamming. The generation of vibration can also shake off the remaining mixture A on the surface of the forming blocks 421 to reduce the risk of the forming blocks 421 being unable to close.

[0064] In an embodiment of the present invention, please refer to Figure 10-11 , guide grooves 44 are provided on both sides of the material placement frame 41, and guide columns 43 are rotatably connected to both sides of the forming block 421. The guide columns 43 are rollingly connected in the guide grooves 44.

[0065] The guide columns 43 are rollingly connected in the guide grooves 44, and the guide columns 43 are rotatably connected to the forming block 421. Therefore, during the displacement process of the forming block 421, it will be restricted by the guide grooves 44, and the slope of the guide grooves 44 is the same as the slope of the sliding groove 42. In this way, under the restriction of the guide grooves 44, the forming block 421 can only slide and unfold along the inclined surface of the sliding groove 42. After unfolding, as shown in the attached Figure 9 , the forming cavities 422 are separated from each other, so that the green body is separated.

[0066] In an embodiment of the present invention, a central shaft 5 is provided on the material placement frame 41, and the central shaft 5 is rotatably connected to the sliding block 3.

[0067] The sliding block 3 can displace in the vertical direction along the vertical frame 2. Therefore, when the sliding block 3 displaces, it can synchronously drive the material placement frame 41 to move in the vertical direction. And since the central shaft 5 is rotatably connected to the sliding block 3, the material placement frame 41 can also rotate synchronously to realize the flipping of the forming block 421 and complete the blanking of the green body.

[0068] In an embodiment of the present invention, please refer to Figure 2-3 , the discharging part includes a flipping assembly 6 and a triggering assembly 7. The flipping assembly 6 includes a force arm 61 and a rotating roller 62. The middle part of the force arm 61 is fixedly installed at the end of the central shaft 5, and a pair of the rotating rollers 62 are respectively rotatably connected to both ends of the force arm 61. The triggering assembly 7 includes a triggering block 71, a second elastic member 72, and an auxiliary plate 73. The triggering block 71 is slidably connected to the auxiliary plate 73, and the second elastic member 72 applies a thrust force to the triggering block 71 in the direction towards the flipping assembly 6.

[0069] After the green compact extrusion is completed, the power unit 10 will move upward rapidly, thereby driving the punch 83 to quickly disengage from the forming block 421. Without the extrusion of the punch 83, the first elastic member 9 will rebound, and the first elastic member 9 will drive the sliding block 3 to displace upward. The upward displacement of the sliding block 3 will drive the mold assembly 4 to move upward synchronously. The lever arm 61 is installed on the central shaft 5. During the upward movement of the mold assembly 4, it will inevitably drive the lever arm 61 to move upward synchronously. At this time, the lever arm 61 maintains a horizontal state. During the upward movement, the rotating roller 62 at the upper end of the lever arm 61 will be blocked by the trigger block 71. Under the obstruction of the trigger block 71, the lever arm 61 will rotate clockwise. When the lever arm 61 rotates, it will synchronously drive the central shaft 5 to rotate. When the central shaft 5 rotates, it will synchronously drive the mold assembly 4 to rotate, thereby realizing the flipping of the mold assembly 4. Under the restriction of the trigger block 71, the rotation angle of the lever arm 61 is at least greater than 90 degrees. When the lever arm 61 disengages from the trigger block 71, it will continue to rotate under the action of inertia. In this way, finally, relying on the self-gravity of the mold assembly 4, the mold assembly 4 can be balanced.

[0070] In an embodiment of the present invention, a slope is provided at one end of the trigger block 71 close to the flipping assembly 6. When the mold assembly 4 moves from the second position to the first position for resetting, the rotating roller 62 abuts against the slope, and the slope will hinder the upward movement of the lever arm 61, so that the lever arm 61 drives the material placing frame 41 to rotate.

[0071] Both the upper and lower surfaces of the trigger block 71 are provided with slopes. In this way, during the downward movement of the mold assembly 4, it is necessary to ensure that the mold assembly 4 does not rotate. Through the slope setting of the trigger block 71, during the downward movement of the mold assembly 4, since the punch 83 is inserted into the forming block 421 and a protrusion is provided at the lower part of the fixed disk 82, and the protrusion abuts against the surface of the forming block 421, therefore, the mold assembly 4 cannot rotate during the downward movement. The lever arm 61 will exert a relatively large pressure on the trigger block 71 during the downward movement, so that the trigger block 71 retracts against the elastic force of the second elastic member 72, so as to realize the trigger block 71 to make way for the lever arm 61 and ensure the smooth downward movement of the mold assembly 4.

[0072] Further, in this process, a two-stage variable pressure during the green compact forming process is realized. When moving from the first position to the trigger block 71, the mold assembly 4 needs to overcome the resistance brought by the trigger block 71 and the resilience of the first elastic member 9 when moving downward. After passing through the trigger block 71, the mold assembly 4 only needs to overcome the resilience of the first elastic member 9. In this way, the pressure changes to gradually increase, then briefly decrease, and then gradually increase, realizing two-stage pressurization, thereby improving the green compact forming quality.

[0073] In an embodiment of the present invention, please refer to Figure 5-6, including a first positioning shaft 51 and a second positioning shaft 52. The first positioning shaft 51 is installed at the lower part of the vertical frame 2, and the second positioning shaft 52 is installed at the upper part of the vertical frame 2. Through holes adapted to the first positioning shaft 51 and the second positioning shaft 52 are provided on both the sliding block 3 and the central shaft 5.

[0074] The central shaft 5 can be positioned by the first positioning shaft 51 and the second positioning shaft 52, ensuring that the blank placing frame 41 is necessarily in a horizontal state when in the first position and the second position, thus ensuring the stability during the extrusion forming of the green body. Enough disconnection segments are reserved between the first positioning shaft 51 and the second positioning shaft 52, which ensures that the central shaft 5 can rotate smoothly to ensure the smooth unloading. And

[0075] It includes a blank receiving part 1 which is used to receive the green body. The blank receiving part 1 can be set as a mesh conveyor belt. The received green body is directly conveyed to the next technological process. The mixture A can directly pass through the mesh conveyor belt and enter the blank receiving box below for centralized collection, or the mesh conveyor belt can be not set and the mixture and the green body can be directly collected centrally and then sorted manually.

[0076] Only some exemplary embodiments of the present invention are described by way of illustration above. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. A preparation process based on silicon nitride ceramic bearing balls, characterized in that: The following steps are involved: S1, raw material mixing: high-purity silicon nitride powder, sintering aid and toughening agent are mixed by wet ball milling to obtain a mixture A; S2, dry pressing: extruding the mixture A to form a green billet; S3, gas pressure sintering: in a nitrogen atmosphere, the green billet is quickly heated to 1800°C, kept at this temperature for 15-35 minutes, then cooled to 1600°C and kept at this temperature for more than 8 hours to inhibit grain growth and obtain a fine-grained structure; S4, precision machining: use diamond grinding wheel for rough grinding, and then use chemical mechanical polishing or magnetorheological polishing for fine polishing to make the surface roughness Ra ≤ 0.01μm.

2. A preparation process based on silicon nitride ceramic bearing balls according to claim 1, characterized in that: The sintering aid adopts Y2O3-MgO system, and its addition ratio is 5-10wt%.

3. A preparation process based on silicon nitride ceramic bearing balls according to claim 1, characterized in that: In S2, the required molding pressure of the green billet is 200-300MPa.

4. A preparation process based on silicon nitride ceramic bearing balls according to claim 1, characterized in that: The toughening agent is silicon carbide whisker, and the addition ratio is 2-5wt.%.

5. A preparation system based on silicon nitride ceramic bearing balls, which is used to implement the preparation process of silicon nitride ceramic bearing balls according to any one of claims 1 to 4, characterized in that: include: Stand (2); A mold assembly (4), the mold assembly (4) comprising a material placement frame (41), a slide groove (42), and a molding block (421), a plurality of the slide grooves (42) are respectively arranged at the upper and lower bottom surfaces of the material placement frame (41), the molding block (421) is slidably connected to the slide groove (42), a molding cavity (422) is arranged on the molding block (421), a pair of the molding cavities (422) are spliced ​​to form a first semicircular cavity, and the mold assembly (4) has a first position and a second position; A sliding block (3), the sliding block (3) is slidably connected to the stand (2), and the material placement frame (41) is rotatably connected to the sliding block (3); A first elastic member (9), wherein the first elastic member (9) applies an upward thrust to the sliding block (3); The pressure assembly (8) comprises a fixed plate (82) and a punch (83), wherein the punch (83) is fixedly mounted on the fixed plate (82), a second semicircular cavity is formed at the bottom of the punch (83), and the first semicircular cavity and the second semicircular cavity can be combined to form a complete spherical cavity; The power unit (10) is used to drive the mold assembly (4) to move from the first position to the second position. During the stroke, the pressure assembly (8) moves downward under the drive of the power unit (10), the punch (83) is inserted into the first semicircular cavity, and the mold assembly (4) moves to the second position under the action of pressure, and the mixed material A in the cavity is squeezed by the punch (83) to form a blank. The unloading part, after the power unit (10) moves upward, under the elastic force of the first elastic member (9), the mold assembly (4) will be reset from the second position to the first position. During this stroke, the unloading part passively drives the mold assembly (4) to rotate so that the blank on the bottom surface of the material placement frame (41) is separated.

6. A preparation system based on silicon nitride ceramic bearing balls according to claim 5, characterized in that: Guide grooves (44) are provided on both sides of the material placement frame (41), and guide pillars (43) are rotatably connected to both sides of the forming block (421), and the guide pillars (43) are rollingly connected in the guide grooves (44).

7. A preparation system based on silicon nitride ceramic bearing balls according to claim 1, characterized in that: The material placement frame (41) is provided with a central shaft (5), and the central shaft (5) is rotatably connected to the sliding block (3).

8. A preparation system based on silicon nitride ceramic bearing balls according to claim 7, characterized in that: The unloading part comprises a flipping assembly (6) and a trigger assembly (7); the flipping assembly (6) comprises a force arm (61) and a rotating roller (62); the middle part of the force arm (61) is fixedly mounted on the end of the central axis (5); a pair of rotating rollers (62) are rotatably connected to the two ends of the force arm (61); the trigger assembly (7) comprises a trigger block (71), a second elastic member (72), and an auxiliary plate (73); the trigger block (71) is slidably connected to the auxiliary plate (73); the second elastic member (72) applies a thrust to the trigger block (71) in the direction of the flipping assembly (6).

9. A preparation system based on silicon nitride ceramic bearing balls according to claim 8, characterized in that: The trigger block (71) is provided with an inclined surface at one end close to the flip assembly (6). When the mold assembly (4) is reset from the second position to the first position, the rotating roller (62) abuts against the inclined surface, which hinders the upward movement of the force arm (61), so that the force arm (61) drives the material placement frame (41) to rotate.

10. A preparation system based on silicon nitride ceramic bearing balls according to claim 1, characterized in that: The invention comprises a first positioning shaft (51) and a second positioning shaft (52), wherein the first positioning shaft (51) is mounted on the lower part of the stand (2), and the second positioning shaft (52) is mounted on the upper part of the stand (2), and the sliding block (3) and the central shaft (5) are both provided with through holes adapted to the first positioning shaft (51) and the second positioning shaft (52).

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