A granulation apparatus and method for cubic boron nitride green compact

Abstract

The application discloses a granulating device and method for cubic boron nitride synthetic blank, which comprises a hopper for storing synthetic blank powder, a granulating device for granulating the synthetic blank powder, and a crushing mechanism for forming granular separation; the feeding port of the hopper is in sealed connection with the discharging port of a feeding machine, the discharging port of the hopper is in sealed connection with the granulating device, the granulating device is in sealed connection with the crushing mechanism, the granulating device comprises a first-stage compression roller mechanism, a second-stage compression roller mechanism and a third-stage compression roller mechanism arranged in sequence from top to bottom, and the compression roller mechanisms are in sealed connection with each other. The mutual cooperation of the three-stage different roller type structures makes the produced granules have greater strength and are not easy to break, the whole process does not need a wetting agent, and the granules do not need secondary heating and drying after successful granulation, so that the purity and granulation rate of the synthetic blank are improved.

Description

Technical Field

[0001] This invention belongs to the field of superhard material synthesis technology, specifically relating to a granulation device and method for cubic boron nitride synthetic preforms. Background Technology

[0002] Cubic boron nitride (CBN) is a synthetic superhard material. The main raw materials for synthesizing CBN single crystals are hexagonal boron nitride and a catalyst. The synthesis preform is made by mixing hexagonal boron nitride powder and catalyst powder in a certain proportion, pre-pressing, and then synthesizing under high temperature and pressure. Hexagonal boron nitride, commonly known as white graphite, is an ultrafine powder with a particle size in the micrometer range. It is a white, easily dispersed powder, difficult to form, and easily generates dust, polluting the environment and posing challenges to weighing, packaging, transportation, and pressing processes. The catalyst is an alkali metal or alkaline earth metal and its nitride. These materials easily adsorb water molecules from the air and react with water, significantly reducing the catalyst's effectiveness and affecting the color and quality of the synthesized CBN crystals. During production, the ambient temperature and humidity need to be controlled within a suitable range to prevent the mixed raw materials of hexagonal boron nitride and catalyst from becoming damp.

[0003] In existing technologies, the common practice is to first press the mixed hexagonal boron nitride billet into blocks using a hydraulic press, then manually crush it into small, irregularly shaped pieces in a subsequent process, followed by weighing and pre-pressing. This method lacks good flowability and weighing accuracy during the weighing and feeding process. Chinese utility model patent CN218262305 U discloses an automatic granulation system for cubic boron nitride raw materials, including a forced feeding hopper, pressing rollers, a pressing motor, spherical crushing rollers, and a crushing roller motor. The system uses dry roller pressing to form spherical granules, which are then mechanically compressed. The granules' strength is primarily determined by intermolecular forces, without the addition of any wetting agents or binders, effectively ensuring raw material purity. Furthermore, it eliminates the need for subsequent drying processes, achieving automated control of the granulation process and effectively overcoming the problems of wet granulation methods. However, because this system directly crushes the sheet material formed by the tableting rollers through the crushing rollers, the hardness of the particles is low, and the synthesized particles are easily broken, resulting in a low granulation rate. In addition, the complex structure of the spiral forced feeding device leads to complicated and difficult cleaning work, and the low degree of coordination between the various parts also results in a low granulation rate. Summary of the Invention

[0004] The purpose of this invention is to provide a granulation device for cubic boron nitride synthetic preforms, which solves the technical problems of easy breakage and low granulation rate of synthetic preform particles.

[0005] The present invention also provides a granulation method using a granulation apparatus for synthesizing cubic boron nitride preforms.

[0006] The technical solution of this invention to solve its technical problem is as follows: A granulation device for cubic boron nitride synthetic preform includes a hopper for storing synthetic preform powder, a granulation device for granulating the synthetic preform powder, and a crushing mechanism for separating the formed granules; the feed inlet of the hopper is sealed to the discharge outlet of a feeder, the discharge outlet of the hopper is sealed to the granulation device, and the granulation device is sealed to the crushing mechanism; the granulation device includes a primary pressure roller mechanism, a secondary pressure roller mechanism, and a tertiary pressure roller mechanism arranged sequentially from top to bottom, and the pressure roller mechanisms at each level are sealed to each other; The primary pressure roller mechanism is used for sheet extrusion of synthetic preforms, and includes sheet rollers and a drive mechanism for driving the sheet rollers to rotate. The secondary pressure roller mechanism is used for strip extrusion of synthetic preforms, and includes strip-shaped rollers and a drive mechanism for driving the strip-shaped rollers to rotate. The three-stage pressure roller mechanism is used for granular extrusion of synthetic preforms, and includes spherical rollers and a drive mechanism for driving the spherical rollers to rotate.

[0007] The specific structure of the sheet-like rollers is as follows: the surface of the sheet-like rollers is provided with elongated grooves with a set depth, length and width, the grooves of the two pairs of rollers correspond one-to-one, and there is a set gap between the two pairs of rollers.

[0008] The specific structure of the strip-shaped rollers is as follows: the surface of the strip-shaped rollers is provided with strip-shaped grooves with a set depth, length and width, the grooves of the two pairs of rollers correspond one-to-one, and there is a set gap between the two pairs of rollers.

[0009] The specific structure of the spherical rollers is as follows: the surface of the spherical rollers is provided with semi-circular spherical sockets with a set diameter, the sockets of the two rollers correspond one-to-one, and there is a set gap between the two rollers.

[0010] The crushing mechanism includes crushing rollers and a drive mechanism for driving the crushing rollers to rotate, which is used to break up the spherical particles squeezed by the rollers.

[0011] The surface of the crushing rollers is provided with columnar spikes.

[0012] It also includes a high-speed mixer for mixing synthetic billet powder, a discharge valve for controlling the discharge speed, a storage mechanism for storing the mixed synthetic billet powder, a level sensor for detecting the height of the synthetic billet powder in the storage mechanism, a vacuum pump for conveying the mixed synthetic billet powder, a level sensor for detecting the height of the synthetic billet powder in the hopper, and a receiving mechanism for collecting the crushed synthetic billet particles.

[0013] A granulation method using a granulation device for cubic boron nitride synthetic preform specifically includes the following steps: S1: Set the device operating parameters, including the first material level threshold, the second material level threshold, the rotation frequency of the first stage pressure roller, the delay time of the first stage pressure roller; the rotation frequency of the second stage pressure roller, the delay time of the second stage pressure roller; the rotation frequency of the first stage pressure roller; the rotation frequency of the second stage pressure roller; the rotation frequency of the third stage pressure roller; and the rotation frequency of the third stage pressure roller. S2: The synthetic billet powder is mixed evenly by a high-speed mixer. The synthetic billet powder is then fed into the storage mechanism through a discharge valve. The level sensor on the storage mechanism detects the height of the synthetic billet powder in the storage mechanism and determines whether the discharge is complete. If yes, the discharge valve is closed and the process proceeds to step S3. If no, the process waits for the discharge to complete. S3: Reset the vacuum feeder, primary roller motor, secondary roller motor, tertiary roller motor and crushing motor. The height of the synthetic billet powder in the hopper is detected by the material level sensor on the hopper. When the height is greater than the first material level threshold, it is determined whether all motors have been reset. If yes, proceed to step S4. If no, wait and give a prompt. S4: Start the primary roller motor, secondary roller motor, tertiary roller motor and crushing motor according to the operating parameters set in step S1 to perform granulation.

[0014] The specific granulation steps are as follows: S3.1: The primary roller motor starts at the rotation frequency of a primary roller; when the running time of the primary roller motor is equal to the delay time of a primary roller, the secondary roller motor starts at the rotation frequency of a secondary roller; when the running time of the secondary roller motor is equal to the delay time of a secondary roller, the tertiary roller motor starts at the rotation frequency of a tertiary roller, and the crushing motor starts at the set rotation frequency; determine whether the height of the synthetic billet powder in the hopper is greater than the first material level threshold. If yes, maintain the state; if no, proceed to step S3.2. S3.2: The primary roller motor operates at the rotation frequency of the second-stage primary pressure roller, while the secondary roller motor, tertiary roller motor, and crushing motor maintain the set rotation frequency; determine whether the height of the synthetic billet powder in the hopper is greater than the second material level threshold. If yes, maintain the state; otherwise, proceed to step S3.3. S3.3: The primary roller motor and crushing motor maintain the set rotation frequency, the secondary roller motor operates at the rotation frequency of the three-stage secondary pressure rollers, and the tertiary roller motor operates at the rotation frequency of the three-stage tertiary pressure rollers. Determine whether the height of the synthetic billet powder in the hopper is zero. If so, start timing. After the timing reaches the set time, the primary roller motor, secondary roller motor, tertiary roller motor and crushing motor stop running, and granulation ends. If not, maintain the status.

[0015] The rotation frequency of the first-stage pressure roller is less than that of the second-stage pressure roller; the rotation frequency of the second-stage pressure roller is greater than that of the third-stage pressure roller; and the rotation frequency of the third-stage pressure roller is greater than that of the third-stage pressure roller.

[0016] The beneficial effects of this invention are as follows: The process utilizes a series of rollers arranged from top to bottom: a primary roller, a secondary roller, and a tertiary roller. The primary roller first pre-presses the synthetic preform into sheets, the secondary roller then presses the sheets into strips, and finally the tertiary roller presses the strips into granules. Crushing rollers break the continuous granules into individual particles. The combination of these three different roller types results in stronger granules that are less prone to breakage. The entire process does not require a wetting agent, and secondary heating and drying are unnecessary after successful granulation, thus improving the purity and granulation rate of the synthetic preform.

[0017] The feeding channel of this device's hopper is a single vacuum pump, which is simple in structure. In addition, all parts of the granulation device are connected in a closed manner. This design can increase the coordination between the parts, reduce dust pollution from powder, improve the safety of the working environment, and thus achieve better production results. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the granulation device of the present invention; Figure 2 This is a schematic diagram of the structure of the primary pressure roller mechanism of the present invention; Figure 3 This is a schematic diagram of the structure of the two-stage pressure roller mechanism of the present invention; Figure 4 This is a schematic diagram of the three-stage pressure roller mechanism of the present invention; Figure 5 This is a flowchart of the granulation method of the present invention; Figure 6 This is a flowchart illustrating the granulation steps of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0020] The synthetic preforms involved in this invention are generally assumed to be hexagonal boron nitride and catalyst.

[0021] like Figure 1As shown, a granulation device for cubic boron nitride synthetic preform includes a high-speed mixer 1 for mixing synthetic preform powder, a discharge valve 2 for controlling the discharge speed, a storage mechanism 4 for storing the mixed synthetic preform powder, a level sensor 3 for detecting the height of the synthetic preform powder in the storage mechanism 4, a vacuum pump 5 for conveying the mixed synthetic preform powder, a hopper 7 for storing the synthetic preform powder, a level sensor 6 for detecting the height of the synthetic preform powder in the hopper 7, a granulation device for granulating the synthetic preform powder, a crushing mechanism 11 for separating the formed granules, and a receiving mechanism 12 for collecting the crushed synthetic preform particles.

[0022] The vacuum feeder 5 is equipped with a back-blowing device. After each feeding, the back-blowing device will back-blow the compressed air to clean the filter element and prevent the feeder from not feeding. In actual production, the feeding time and back-blowing time can be set as needed to ensure that the synthetic raw material powder can be conveyed normally.

[0023] The feed inlet of the hopper is sealed to the discharge outlet of the feeder, and the discharge outlet of the hopper is sealed to the granulation device; the granulation device is sealed to the crushing mechanism.

[0024] The crushing mechanism includes crushing rollers and a drive mechanism for driving the crushing rollers to rotate, which is used to break up the edge-connected particles squeezed by the spherical rollers. The surface of the crushing rollers is provided with columnar spikes.

[0025] The granulation device includes a primary pressure roller mechanism 8, a secondary pressure roller mechanism 9, and a tertiary pressure roller mechanism 10 arranged sequentially from top to bottom, with each level of pressure roller mechanism being sealed and connected.

[0026] like Figure 2 As shown, the primary pressure roller mechanism 8 is used for sheet extrusion of synthetic preforms, including sheet rollers 80 and a drive mechanism for driving the sheet rollers to rotate.

[0027] Two sheet-shaped rollers 80 are respectively connected to a main shaft 81 and a driven shaft 82. The main shaft 81 is equipped with a coupling 83, a driving wheel 84, and a roller pulley 86. The driven shaft 82 is equipped with a coupling 83 and a driven wheel 85. The roller pulley 86 is connected to a motor pulley 88 via a belt 87. The motor pulley 88 is connected to a primary roller motor 89.

[0028] During operation, the primary roller motor 89 drives the motor pulley 88 to rotate, and the motor pulley 88 drives the roller pulley 86 to rotate via the belt 87. The drive pulley 84 drives the driven pulley 85 to rotate, thereby rotating the sheet roller 1 to achieve the purpose of processing the synthetic preform into sheet form.

[0029] The specific structure of the sheet-like rollers is as follows: the surface of the sheet-like rollers is provided with elongated grooves with a set depth, length and width, the grooves of the two pairs of rollers correspond one-to-one, and there is a set gap between the two pairs of rollers.

[0030] The depth is set in the range of 0.4-0.6mm, with a preferred depth of 0.5mm; the length is set in the range of 8-10mm, with a preferred length of 10mm; the width is set in the range of 4-6mm, with a preferred width of 5mm; and the gap is set in the range of 0.3-0.5mm, with a preferred gap of 0.3mm.

[0031] The dry powder of the synthetic preform first undergoes preliminary pre-compression by a primary roller, resulting in intermittent and non-formed pre-compressed sheets. Therefore, the primary roller is set to have the highest rotation frequency among the three roller stages, allowing the intermittently non-formed sheet-like material to accumulate to a certain amount on the secondary roller below.

[0032] like Figure 3 As shown, the secondary pressure roller mechanism 9 is used for strip extrusion of synthetic preforms, including strip rollers 90 and a drive mechanism for driving the strip rollers to rotate.

[0033] Two strip-shaped rollers 90 are respectively connected to the main shaft 91 and the driven shaft 92. The main shaft 91 is equipped with a coupling 93, a driving wheel 94, and a roller pulley 96. The driven shaft 92 is equipped with a coupling 93 and a driven wheel 95. The roller pulley 96 is connected to the motor pulley 98 via a belt 97. The motor pulley 98 is connected to the secondary roller motor 99.

[0034] During operation, the secondary roller motor 99 drives the motor pulley 98 to rotate, and the motor pulley 98 drives the roller pulley 96 to rotate via the belt 97. The drive pulley 94 drives the driven pulley 95 to rotate, thereby rotating the strip roller 90 to achieve the purpose of processing the synthetic preform into strips.

[0035] The specific structure of the strip-shaped rollers is as follows: the surface of the strip-shaped rollers is provided with strip-shaped grooves with a set depth, length and width, the grooves of the two pairs of rollers correspond one-to-one, and there is a set gap between the two pairs of rollers.

[0036] The depth is set in the range of 0.8-1mm, with a preferred depth of 1mm; the length is set to be equal to the length of the rollers, generally in the range of 150-200mm; the width is set in the range of 2-2.5mm, with a preferred width of 2mm; and the gap is set in the range of 0.3-0.5mm, with a preferred gap of 0.3mm.

[0037] The rotation frequency of the secondary rollers is lower than that of the primary rollers but higher than that of the tertiary rollers. After being squeezed by the secondary rollers, the primary pre-pressed sheets piled on the secondary rollers have a certain packing density. The initially formed hexagonal strips are squeezed out from the secondary rollers and fall above the tertiary rollers.

[0038] like Figure 4 As shown, the three-stage pressure roller mechanism 10 is used for granular extrusion of synthetic preforms, including spherical rollers 100 and a drive mechanism for driving the spherical rollers to rotate.

[0039] Two spherical rollers 100 are respectively connected to the main shaft 101 and the driven shaft 102. The main shaft 101 is equipped with a coupling 103, a driving wheel 104, and a roller pulley 106. The driven shaft 102 is equipped with a coupling 103 and a driven wheel 105. The roller pulley 106 is connected to the motor pulley 108 via a belt 107. The motor pulley 108 is connected to a three-stage roller motor 109.

[0040] During operation, the three-stage roller motor 109 drives the motor pulley 108 to rotate, and the motor pulley 108 drives the roller pulley 106 to rotate via the belt 107. The drive pulley 104 drives the driven pulley 105 to rotate, thereby causing the spherical roller 100 to rotate, achieving the purpose of spherical processing of the synthetic preform.

[0041] The specific structure of the spherical rollers is as follows: the surface of the spherical rollers is provided with semi-circular spherical sockets with a set diameter, the sockets of the two rollers correspond one-to-one, and there is a set gap between the two rollers.

[0042] The diameter is set in the range of 3-5mm, preferably 3mm; the gap is set in the range of 0.4-0.6mm, preferably 0.5mm.

[0043] After three extrusions, the spherical synthetic preform particles are joined together into large sheets and extruded from the three-stage rollers. After being crushed and sized by the columnar spikes on the surface of the crushing rollers directly below, they enter the receiving mechanism.

[0044] The frequencies of the three rollers mentioned above are controlled by different variable frequency motors. The frequency of the frequency converter can be changed according to process requirements to achieve the granulation requirements. Specifically, the frequency converter controls the motor to rotate at a specified frequency through commands sent by the system.

[0045] This device ensures that the chemical properties of the synthetic preform are not damaged and the effective content of the product is not reduced without adding any water, binder or wetting agent. The dry powder of the synthetic preform (hexagonal boron nitride and catalyst) is directly compressed and molded into spherical small particles by the dry powder particle preparation method, with a particle formation rate of over 95%. This increases the bulk density of the raw materials, making it easier to weigh, package, press and transport.

[0046] This device eliminates the need for secondary heating and drying after granulation, resulting in fewer steps and higher efficiency. It can also be integrated with a host computer and PLC controller for fully automated control. Because the structures are sealed together, the operation is pollution-free, simple, easy to clean, and improves the physical properties of the product (such as flowability, air permeability, filling properties, and bulk density). It also prevents segregation, bridging, pulsation, and agglomeration from occurring during subsequent weighing and batching processes in the synthesis column pressing process.

[0047] Therefore, this device not only improves the formability and hardness of the pre-compression column, but also increases production efficiency and product quality, saves manpower, reduces the labor intensity of workers, optimizes the production environment, and saves energy and reduces consumption.

[0048] like Figure 5 As shown, a granulation method using a granulation device for cubic boron nitride synthetic preform specifically includes the following steps: S1: Set the device operating parameters, including the first material level threshold h1, the second material level threshold h2, the rotation frequency f11 of the first-stage pressure roller (generally set to 20-25 Hz), the delay time t11 of the first-stage pressure roller (generally set to 3-5 s), the rotation frequency f12 of the first-stage pressure roller (generally set to 15-20 Hz), the delay time t12 of the first-stage pressure roller (generally set to 2-4 s), the rotation frequency f13 of the first-stage pressure roller (generally set to 10-15 Hz), the rotation frequency f21 of the second-stage pressure roller (generally set to 25-30 Hz), the rotation frequency f32 of the third-stage pressure roller (generally set to 10-15 Hz), and the rotation frequency f33 of the third-stage pressure roller (generally set to 5-8 Hz). The above three distances can be adjusted according to the actual situation. The rotation frequency needs to be properly matched. That is, in the middle material level, in order to prevent insufficient pressure due to insufficient material and failure of the synthetic preform powder to form, the previous stage needs to have a sufficient amount of accumulation to ensure that the next stage can extrude and form. Therefore, at this time, the first-stage roller motor needs to increase the rotation speed. Increasing the speed can ensure the amount of material falling onto the second-stage roller.

[0049] Similarly, as the material gradually decreases, when the material level reaches the later stage, in order to achieve complete granulation, the speed of the primary roller remains unchanged, while the speeds of the secondary and tertiary rollers are reduced according to their respective settings. This ensures that a certain amount of material accumulates above the rollers, guaranteeing granulation formation. A suitable rotation frequency is essential for effective granulation efficiency and success rate, and therefore can be adjusted according to actual conditions.

[0050] S2: The synthetic billet powder is mixed evenly by a high-speed mixer. The synthetic billet powder is then fed into the storage mechanism through a discharge valve. The level sensor on the storage mechanism detects the height of the synthetic billet powder in the storage mechanism and determines whether the discharge is complete. If yes, the discharge valve is closed and the process proceeds to step S3. If no, the process waits for the discharge to complete.

[0051] The storage mechanism generally uses a storage hopper, and the material level sensor is an ultrasonic material level sensor. The criterion for judging the end of material discharge is to detect the material level height in the storage hopper. When the height is close to zero, the vacuum pump stops pumping after a 30-second delay, and the material pumping process ends.

[0052] S3: Reset the vacuum feeder, primary roller motor, secondary roller motor, tertiary roller motor, and crushing motor. The height of the synthetic billet powder in the hopper is detected by a level sensor on the hopper. When the height exceeds the first level threshold h1, determine if all motors have reset. If yes, proceed to step S4; otherwise, wait and issue a prompt. The prompt can be displayed in an error dialog box on the host computer's human-machine interface. After all motors have reset, proceed to step S4.

[0053] S4: Start the primary roller motor, secondary roller motor, tertiary roller motor and crushing motor according to the operating parameters set in step S1 to perform granulation.

[0054] An ultrasonic level sensor is used to detect the height of the material level in the hopper in real time. The controller adopts a segmented frequency conversion control method for the primary roller motor 89, the secondary roller motor 99, and the tertiary roller motor 109. The frequency parameters of each roller can be adjusted according to the granulation requirements of multiple cubic boron nitride varieties and the characteristics of different hexagonal boron nitride and catalyst mixtures to meet the particle index requirements. It also solves the problems of excessive residual material that is difficult to clean in conventional dry granulation methods, and the problem of intermittent granulation and failure to form due to the gradual reduction of residual material in the hopper at the end of granulation. It largely avoids the waste of materials and energy.

[0055] like Figure 6 As shown, the specific granulation steps are as follows: S3.1: The primary roller motor starts at the primary roller rotation frequency f11; when the running time of the primary roller motor is equal to the primary roller delay time t11, the secondary roller motor starts at the secondary roller rotation frequency f12; when the running time of the secondary roller motor is equal to the secondary roller delay time t12, the tertiary roller motor starts at the tertiary roller rotation frequency f13, and the crushing motor starts at the set rotation frequency; determine whether the height of the synthetic billet powder in the hopper is greater than the first material level threshold h1. If yes, maintain the state; if no, proceed to step S3.2. S3.2: The first-stage roller motor runs at the rotation frequency f21 of the second-stage first-stage pressure roller, while the second-stage roller motor, the third-stage roller motor, and the crushing motor maintain the set rotation frequency; determine whether the height of the synthetic billet powder in the hopper is greater than the second material level threshold h2. If yes, maintain the state; otherwise, proceed to step S3.3. S3.3: The primary roller motor and crushing motor maintain the set rotation frequency, the secondary roller motor operates at the three-stage secondary pressure roller rotation frequency f32, and the tertiary roller motor operates at the three-stage tertiary pressure roller rotation frequency f33. Determine whether the height of the synthetic billet powder in the hopper is zero. If yes, start timing. After the timing reaches the set time, which is generally set to five minutes, the primary roller motor, secondary roller motor, tertiary roller motor and crushing motor stop running, and granulation ends. If not, maintain the status.

[0056] The rotation frequency f11 of the first-stage pressure roller is less than the rotation frequency f21 of the second-stage pressure roller; the rotation frequency f12 of the second-stage pressure roller is greater than the rotation frequency f32 of the third-stage pressure roller; and the rotation frequency f13 of the first-stage pressure roller is greater than the rotation frequency f33 of the third-stage pressure roller.

[0057] In practical applications, a 10-inch HMI (Human Machine Interface) host computer is used to display and set production parameter data. It communicates in real-time with the lower-level PLC controller via a RS-232 serial port. The PLC controller outputs six digital signals: audible and visual alarm control, vacuum feeder start / stop control, and start / stop control for the primary, secondary, and tertiary roller motors. It also outputs eight analog inputs: material level display for the storage bin, hopper, primary roller motor rotation frequency display, secondary roller motor rotation frequency display, tertiary roller motor rotation frequency display, and motor load current display. Finally, it outputs three analog signals: speed control for the primary, secondary, and tertiary roller motors.

[0058] The host computer's human-machine interface screen also features real-time detection and alarm functions for the current of the three-level roller motors. During granulation, if the granulation extrusion pressure is too high, causing overload or stalling of the roller motors, the current of the roller motors will increase. This can be displayed on the human-machine interface screen, and the PLC controller will output a switch signal. The audible and visual alarm on the control cabinet will then sound an alarm and flash a light to alert the user. At the same time, the PLC will issue an alarm control signal. At this point, all three levels of roller motors will reset, and granulation will be suspended until the fault is cleared and everything returns to normal. Granulation can then resume.

[0059] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A granulation method using a granulation apparatus for cubic boron nitride synthetic preforms, characterized in that, Includes the following steps: S1: Set the device operating parameters, including the first material level threshold, the second material level threshold, the rotation frequency of the first-stage pressure roller, and the delay time of the first-stage pressure roller; Rotation frequency of a first-stage secondary pressure roller; delay time of a first-stage secondary pressure roller; rotation frequency of a first-stage tertiary pressure roller; rotation frequency of a second-stage primary pressure roller; rotation frequency of a third-stage secondary pressure roller; rotation frequency of a third-stage tertiary pressure roller; S2: The synthetic billet powder is mixed evenly by a high-speed mixer. The synthetic billet powder is then fed into the storage mechanism through a discharge valve. The level sensor on the storage mechanism detects the height of the synthetic billet powder in the storage mechanism and determines whether the discharge is complete. If yes, the discharge valve is closed and the process proceeds to step S3. If no, the process waits for the discharge to complete. S3: Reset the vacuum feeder, primary roller motor, secondary roller motor, tertiary roller motor and crushing motor. The height of the synthetic billet powder in the hopper is detected by the material level sensor on the hopper. When the height is greater than the first material level threshold, it is determined whether all motors have been reset. If yes, proceed to step S4. If no, wait and give a prompt. S4: Start the primary roller motor, secondary roller motor, tertiary roller motor and crushing motor according to the operating parameters set in step S1 to perform granulation; Step S4 specifically involves: S4.1: The primary roller motor starts at the rotation frequency of a primary roller; when the running time of the primary roller motor is equal to the delay time of a primary roller, the secondary roller motor starts at the rotation frequency of a secondary roller. When the running time of the secondary roller motor is equal to the delay time of a secondary roller, the tertiary roller motor starts at the rotation frequency of a tertiary roller, and the crushing motor starts at the set rotation frequency; determine whether the height of the synthetic billet powder in the hopper is greater than the first material level threshold. If yes, maintain the state; if no, proceed to step S4.

2. S4.2: The primary roller motor operates at the rotation frequency of the secondary primary pressure roller, while the secondary roller motor, tertiary roller motor, and crushing motor maintain the set rotation frequency; determine whether the height of the synthetic billet powder in the hopper is greater than the second material level threshold. If yes, maintain the state; otherwise, proceed to step S4.

3. S4.3: The primary roller motor and crushing motor are set to maintain their rotation frequency; the secondary roller motor operates at the rotation frequency of the three-stage secondary pressure rollers; the tertiary roller motor operates at the rotation frequency of the three-stage tertiary pressure rollers. The system checks if the height of the synthetic billet powder in the hopper is zero. If so, timing begins. After the set time is reached, the primary, secondary, and tertiary roller motors and the crushing motor stop operating, and granulation ends. If not, the system remains unchanged. The granulation device includes a hopper for storing synthetic billet powder, a granulation device for granulating the synthetic billet powder, and a crushing mechanism for separating shaped granules; the feed inlet of the hopper is sealed to the discharge outlet of the feeder, the discharge outlet of the hopper is sealed to the granulation device, and the granulation device is sealed to the crushing mechanism; the granulation device includes a primary pressure roller mechanism, a secondary pressure roller mechanism, and a tertiary pressure roller mechanism arranged sequentially from top to bottom, and the pressure roller mechanisms at each level are sealed to each other. The primary pressure roller mechanism is used for sheet extrusion of the synthetic billet, and includes sheet rollers and a drive mechanism for driving the sheet rollers to rotate. The secondary pressure roller mechanism is used for strip extrusion of the synthetic billet, and includes strip-shaped rollers and a drive mechanism for driving the strip-shaped rollers to rotate. The three-stage pressure roller mechanism is used for granular extrusion of synthetic billets, and includes spherical rollers and a drive mechanism for driving the spherical rollers to rotate.

2. The granulation method of the granulation apparatus using cubic boron nitride synthetic preform according to claim 1, characterized in that: The specific structure of the sheet-like rollers is as follows: the surface of the sheet-like rollers is provided with elongated grooves with a set depth, length and width, the grooves of the two pairs of rollers correspond one-to-one, and there is a set gap between the two pairs of rollers.

3. The granulation method of the granulation apparatus using cubic boron nitride synthetic preform according to claim 1, characterized in that: The specific structure of the strip-shaped rollers is as follows: the surface of the strip-shaped rollers is provided with strip-shaped grooves with a set depth, length and width, the grooves of the two pairs of rollers correspond one-to-one, and there is a set gap between the two pairs of rollers.

4. The granulation method of the granulation apparatus using cubic boron nitride synthetic preform according to claim 1, characterized in that: The specific structure of the spherical rollers is as follows: the surface of the spherical rollers is provided with semi-circular spherical sockets with a set diameter, the sockets of the two rollers correspond one-to-one, and there is a set gap between the two rollers.

5. The granulation method using the granulation apparatus for cubic boron nitride synthetic preform according to claim 1, characterized in that: The crushing mechanism includes crushing rollers and a drive mechanism for driving the crushing rollers to rotate, which is used to break up the spherical particles squeezed by the rollers.

6. The granulation method using the granulation apparatus for cubic boron nitride synthetic preform according to claim 5, characterized in that: The surface of the crushing rollers is provided with columnar spikes.

7. The granulation method of the granulation apparatus using cubic boron nitride synthetic preform according to claim 1, characterized in that: It also includes a high-speed mixer for mixing synthetic billet powder, a discharge valve for controlling the discharge speed, a storage mechanism for storing the mixed synthetic billet powder, a level sensor for detecting the height of the synthetic billet powder in the storage mechanism, a vacuum pump for conveying the mixed synthetic billet powder, a level sensor for detecting the height of the synthetic billet powder in the hopper, and a receiving mechanism for collecting the crushed synthetic billet particles.

8. The granulation method of the granulation apparatus using cubic boron nitride synthetic preform according to claim 1, characterized in that: The rotation frequency of the first-stage pressure roller is less than that of the second-stage pressure roller; the rotation frequency of the second-stage pressure roller is greater than that of the third-stage pressure roller; and the rotation frequency of the third-stage pressure roller is greater than that of the third-stage pressure roller.

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