A sealing fixture for alkaline washing of a single crystal furnace

Abstract

This invention discloses a closed fixture for alkaline washing of a single crystal furnace, belonging to the technical field of single crystal furnace cleaning equipment. The fixture includes: a movable base with casters at the bottom; a support frame and mounting base; a first electric push rod for driving the cleaning components to rise and fall; a secondary lifting mechanism including a mounting platform, a sealing cover, and a second electric push rod, the sealing cover being independently movable and sealing the furnace opening; the cleaning components include a drive motor and a brush head, the motor shaft being a hollow tube, the upper end of which is rotatably sealed to a first piston rod via a rotating connecting cover, and the lower end fixing the brush head; an alkaline washing solution and clean water supply system; a waste liquid collection and detection system, equipped with a pH sensor and a conductivity sensor for online waste liquid detection; and a controller. This invention can achieve in-situ alkaline washing-rinsing-drying and closed-loop cleanliness detection. The brush head can reciprocate up and down to clean the sidewalls and clean the bottom at specific points. The sealing cover maintains a constant seal during the cleaning process through dynamic compensation by a pressure sensor, ensuring thorough cleaning without dead angles and with high safety and efficiency.

Description

Technical Field

[0001] This invention relates to the field of single crystal furnace cleaning equipment technology, specifically a closed fixture for alkaline cleaning of single crystal furnaces. Background Technology

[0002] Monocrystalline silicon is the fundamental material for manufacturing semiconductor chips and photovoltaic solar cells, and it is mainly grown in a single-crystal furnace using the Czochralski method. During the single-crystal growth process, molten silicon residue adheres to the inner wall of the quartz crucible, while a dense silicon oxide deposit forms on the surface of graphite thermal field components (such as heaters and insulation cylinders). If these residues and deposits are not removed in a timely and thorough manner, they will directly affect the purity, quality, and yield of subsequent crystal growth.

[0003] Currently, the following methods are mainly used for cleaning single crystal furnace crucibles and hot zone components: Manual wiping and cleaning: Operators use a scouring pad and vacuum cleaner to manually wipe the inner wall of the crucible and hot-field components. This method is labor-intensive, inefficient, and the cleaning effect depends on the operator's experience, making it difficult to guarantee consistency. Furthermore, manual operation can easily generate dust, posing occupational health risks.

[0004] Disassembly followed by external cleaning: The crucible or graphite components are removed from the furnace and transported to a specialized cleaning station for acid or alkali washing. This method requires prolonged downtime, the component disassembly and reassembly process is cumbersome, and repeated disassembly and reassembly can easily cause damage to precision components or installation errors.

[0005] Therefore, a highly automated, closed-loop fixture for alkaline cleaning of crucibles or graphite single crystal furnaces is needed to replace manual wiping and cleaning and post-disassembly external cleaning. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a closed fixture for alkaline washing of a single crystal furnace, which solves the problems mentioned in the background section.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a sealing fixture for alkaline washing of a single crystal furnace, comprising: The mobile base has casters with locking function at the bottom; A bracket is fixed to the movable base, and the upper end of the bracket is provided with a mounting base that extends horizontally beyond the movable base; The first electric push rod is mounted on the mounting base; The cleaning component is located below the mounting base and is driven to rise and fall by the first piston rod of the first electric push rod; The secondary lifting mechanism includes a mounting platform, a sealing cover, and a second electric push rod; the mounting platform moves up and down synchronously with the cleaning component; the sealing cover is located below the mounting platform; the second electric push rod is mounted on the mounting platform and is used to drive the sealing cover to move up and down independently relative to the mounting platform. An alkaline cleaning solution and clean water supply system is installed on the movable base and is used to supply alkaline cleaning solution and clean water into the sealed cover; The cleaning component includes a drive motor and a brush head; the housing of the drive motor is fixedly connected to the mounting platform, and the shaft of the drive motor is a hollow tube; the upper end of the hollow tube is rotatably and sealingly connected to the first piston rod through a rotating connecting cover; the brush head is fixed to the lower end of the hollow tube. A waste liquid collection and detection system, connected to the rotary joint, is used to extract liquid from the crucible and detect its electrical signal. The controller is used to control the sequence of actions and operating parameters of each component.

[0008] Preferably, the rotating connecting cover includes: the rotating connecting cover having a hollow cavity; The upper end of the hollow cavity is fixedly connected to the first piston rod; The lower end of the hollow cavity is provided with a rotary sealing joint, which is connected to the upper end of the hollow tube, and the hollow tube is coaxially aligned with the first piston rod. A three-way pipe is provided on the side wall of the hollow cavity, and a first solenoid valve is provided on the first branch of the three-way pipe. The first branch is connected to the waste liquid collection and detection system.

[0009] Preferably, the waste liquid collection and detection system includes: Waste liquid collection tank, with a drain valve installed on its lower side wall; Vacuum pump; The detection device includes a flow cell having an inlet and an outlet. The flow cell is equipped with a pH sensor and a conductivity sensor; The pH sensor is used to measure the pH value of the liquid flowing through it; The conductivity sensor is used to measure the conductivity value of the liquid flowing through it, and is used to characterize the amount of silicon residue. The outlet of the first solenoid valve is connected to the inlet of the flow tank, the outlet of the flow tank is connected to the inlet of the vacuum pump, and the outlet of the vacuum pump is connected to the waste liquid collection tank. During suction, the liquid in the crucible flows sequentially through the first solenoid valve, the flow cell, and the vacuum pump before entering the waste liquid collection tank. The pH sensor and the conductivity sensor output detection signals in real time as the liquid flows through.

[0010] Preferably, the three-way pipe also has a second branch pipe, on which a second solenoid valve is provided. The second solenoid valve is connected to a hot air blower for blowing hot air into the crucible to dry the moisture.

[0011] Preferably, an inner tube is provided on the inner wall of the hollow tube, and the inner tube extends along the axial direction of the hollow tube; The lower end of the inner tube is equipped with a first pressure sensor, which is used to detect the pressure signal when the brush head contacts the bottom of the crucible; The signal line and power line of the first pressure sensor run from inside the inner tube, extend to a position near the bottom of the rotary sealing joint, and then pass through the side wall of the hollow tube. The rotor of the slip ring assembly is provided on the side wall of the hollow tube, and the stator of the slip ring assembly is provided on the stationary part of the rotary sealing joint. The signal line and power line are electrically connected to the rotor of the slip ring assembly, and the stator of the slip ring assembly is electrically connected to the controller; the slip ring assembly is used to transmit the signal and power supply of the sensor on the rotating hollow tube to the stationary controller.

[0012] Preferably, four round rods are arranged in a square array on the mounting platform; The four round rods pass upward through the mounting base. A first linear bearing is provided at the contact point between the round rod and the mounting base. The first linear bearing is fixedly connected to the mounting base, and the round rod is slidably engaged with the first linear bearing. The housing of the drive motor is embedded and fixed on the mounting platform; A cross bracket is fixed on the first piston rod, and the four ends of the cross bracket are respectively fixedly connected to the upper ends of the four round rods.

[0013] Preferably, the four second electric push rods are arranged circumferentially around the drive motor; Each of the second electric push rods has a second pressure sensor at the bottom of its second piston rod, and the other end of the second pressure sensor is connected to the upper end face of the sealing cover. The sealing cover is bowl-shaped, and a rubber gasket is provided on its inner wall; A linear rotary bearing is provided at the center of the sealing cover. The linear rotary bearing is sleeved on the first piston rod to realize the relative rotation and relative axial sliding between the sealing cover and the first piston rod; a sealing ring is provided on the rotary linear bearing. The second pressure sensor is electrically connected to the controller and is used to detect the pressure applied to the sealing cover by each of the second electric push rods in real time, so as to control the clamping force between the sealing cover and the crucible furnace opening.

[0014] Preferably, the brush head includes a crucible sidewall brushing section and a crucible bottom brushing section; The sidewall brushing section includes: a plurality of first mounting rings spaced apart along the axial direction of the hollow tube, each of the first mounting rings having a plurality of radially extending support rods circumferentially arranged on its sidewall, each support rod being fitted with a spring; and a plurality of support plates, each support plate having bristles pointing toward the inner wall of the crucible, each support plate having a plurality of through holes opened in the vertical direction, the through holes being slidably engaged with the plurality of support rods in the same vertical projection direction, the spring force causing the support plate and bristles to always press against the inner wall of the crucible; The bottom brushing section includes: a second support ring, fixed to the lower end of the hollow tube or below the side wall brushing section; and multiple arc-shaped rods circumferentially arranged on the side wall of the second support ring, the arc-shaped rods being provided with bristles pointing towards the bottom of the crucible, the curvature of the arc-shaped rods being adapted to the shape of the bottom of the crucible when the bottom brushing section rotates with the hollow tube.

[0015] Preferably, the alkaline washing solution and clean water supply system includes: The alkaline washing solution container and the clean water container are respectively mounted on the movable base; The first water pump has its inlet connected to the alkaline washing solution container and its outlet connected to the first inlet provided on the sealing cover to pump the alkaline washing solution into the crucible. The second water pump has its inlet connected to the clean water container and its outlet connected to the second inlet provided on the sealing cover to pump clean water into the crucible.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention employs a two-stage lifting mechanism. The sealing cover, driven by an independent second electric push rod, pre-presses against the furnace opening to form a sealed cavity before the brush head enters the crucible. The inner wall of the sealing cover is equipped with rubber gaskets, and a linear rotary bearing with a sealing ring is located in the center, ensuring that the sealing cover remains stationary and tightly fitted to the furnace opening during the brush head's rotation and lifting process. This structure effectively prevents alkali splashing and harmful gas leakage, ensuring operator safety and equipment cleanliness.

[0017] 2. During the suction process, the waste liquid collection and detection system of this invention uses pH and conductivity sensors in the flow tank to detect the pH and conductivity of the waste liquid in real time. The conductivity value is positively correlated with the silicate concentration in the liquid, which can characterize the amount of residual silica. The control system determines whether the cleaning has reached its endpoint based on the detection signal. If it fails, it automatically repeats alkaline washing or rinsing, forming a closed-loop control of "cleaning-detection-feedback-rewashing". This completely changes the traditional open-loop cleaning mode that relies on manual visual inspection or fixed time, ensuring the consistency and reliability of the cleaning results.

[0018] 3. The drive motor shaft of this invention is a hollow tube with an inner tube for wiring. The first pressure sensor is installed near the brush head, and its signal and power lines are led out through the inner tube and connected to the controller via a slip ring assembly (the rotor rotates with the hollow tube, while the stator is fixed to a stationary component). This design ensures that the hollow tube can be used for liquid aspiration while enabling power supply and real-time signal transmission to the sensor on the rotating component, providing a hardware foundation for intelligent functions such as bottom detection and pressure control.

[0019] 4. The present invention connects to a hot air blower through the second branch of the three-way pipe. After cleaning and rinsing, hot air is blown into the crucible to quickly dry the inner wall of the crucible and the brush head, avoiding residual moisture from adsorbing dust in the air or causing metal parts to rust, thus providing a dry and clean environment for subsequent single crystal growth. Attached Figure Description

[0020] Figure 1 A schematic diagram of the structure of the alkaline washing and sealing fixture for a single crystal furnace; Figure 2 This is a structural diagram of the main working components; Figure 3 A cross-sectional structural diagram of the main working components; Figure 4 for Figure 3 Schematic diagram of the structure at point A in the middle; Figure 5 for Figure 3 Schematic diagram of the structure at point B.

[0021] In the diagram: 1. Movable base; 2. Casters; 3. Bracket; 4. Mounting frame; 5. First electric push rod; 6. First piston rod; 7. Drive motor; 8. Brush head; 9. Mounting platform; 10. Hollow tube; 11. Rotary connecting cover; 12. Sealing cover; 13. Second electric push rod; 14. Second piston rod; 15. Linear rotary bearing; 16. Alkaline washing solution container; 17. Clean water container; 18. First water pump; 19. Second water pump; 20. First inlet; 21. Second inlet; 22. Waste liquid collection tank; 23. Vacuum pump; 24. Detection device; 25. Drain valve. 25. First solenoid valve; 26. Rotary sealing joint; 27. T-pipe; 28. First branch pipe; 29. ​​Second branch pipe; 30. Second solenoid valve; 31. Hot air blower; 32. Inner pipe; 33. First pressure sensor; 34. Rotor; 35. Stator; 36. Rubber ring; 37. Round rod; 38. First linear bearing; 39. Cross bracket; 40. Second pressure sensor; 41. First mounting ring; 42. Support rod; 43. Spring; 44. Support plate; 45. Brush bristles; 46. Second support ring; 47. Arc rod; 48. Rubber screen plate; 49. Detailed Implementation

[0022] 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. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0023] Please see Figures 1 to 5 The present invention provides a technical solution: a sealing fixture for alkaline washing of a single crystal furnace.

[0024] This embodiment provides a closed fixture for alkaline washing of a single crystal furnace, used for in-situ alkaline washing, rinsing, drying, and cleanliness testing of the quartz crucible and graphite hot zone components of a Czochralski single crystal furnace.

[0025] The tooling includes: The mobile base 1 has four universal wheels 2 with locking function installed at the bottom, which makes it easy for the tooling to move between multiple furnace platforms. After it is in place, the base can be fixed to the ground by locking mechanism.

[0026] The bracket 3 is fixed to the movable base 1, and the upper end of the bracket 3 is provided with a horizontal mounting base 4 that extends beyond the movable base 1. The mounting base 4 is used to support the lifting mechanism and cleaning components, and its protruding part sits above the furnace opening of the single crystal furnace.

[0027] The first electric push rod 5 is vertically mounted at the center of the mounting base 4, with its first piston rod 6 extending downwards to drive the overall lifting and lowering of the cleaning components. The first electric push rod 5 uses a servo electric cylinder with a built-in absolute encoder, which can precisely control the displacement and speed of the piston rod.

[0028] The cleaning component is located below the mounting base 4 and is driven to move up and down by the first piston rod 6. The cleaning component includes a drive motor 7 and a brush head 8. The housing of the drive motor 7 is fixedly connected to the mounting platform 9; the rotating shaft of the drive motor 7 is a hollow tube 10, the upper end of which is rotatably and sealingly connected to the first piston rod 6 through a rotating connecting cover 11, and the lower end is fixedly mounted with the brush head 8.

[0029] The secondary lifting mechanism includes a mounting platform 9, a sealing cover 12, and four second electric push rods 13. The mounting platform 9 rises and falls synchronously with the cleaning components (i.e., the mounting platform 9 is fixedly connected to the housing of the drive motor 7 and rises and falls with the first piston rod 6). The four second electric push rods 13 are evenly arranged circumferentially around the drive motor 7, and their housings are fixed to the mounting platform 9. The second piston rods 14 extend downwards, driving the sealing cover 12 to rise and fall independently relative to the mounting platform 9. The sealing cover 12 is bowl-shaped, and its inner wall is lined with alkali-resistant rubber gaskets for sealing against the end face of the single crystal furnace opening. A through hole is provided in the center of the sealing cover 12, and a linear rotary bearing 15 is installed in the through hole. The linear rotary bearing 15 is sleeved on the first piston rod 6, allowing the sealing cover 12 to slide axially and rotate circumferentially relative to the first piston rod 6. PTFE sealing rings are provided at both ends of the linear rotary bearing 15 to prevent alkali solution from leaking along the first piston rod 6.

[0030] An alkaline washing solution and clean water supply system, mounted on a movable base 1, includes an alkaline washing solution container 16, a clean water container 17, a first water pump 18, and a second water pump 19. The alkaline washing solution container 16 stores a NaOH solution with a mass fraction of 15%~30%, and the clean water container 17 stores deionized water. The inlet of the first water pump 18 is connected to the alkaline washing solution container 16, and its outlet is connected to a first inlet 20 on a sealing cover 12 via an alkali-resistant hose. The inlet of the second water pump 19 is connected to the clean water container 17, and its outlet is connected to a second inlet 21 on a sealing cover 12 via a hose.

[0031] A waste liquid collection and detection system is used to draw liquid from a crucible during alkaline washing or rinsing and to detect its pH value and residual silicon content online. The system includes a waste liquid collection tank 22, a vacuum pump 23, and a detection device 24. A drain valve 25 is provided on the lower side wall of the waste liquid collection tank 22 for periodically discharging waste liquid. The detection device 24 includes a flow cell containing an industrial-grade pH sensor and a conductivity sensor. The inlet of the flow cell is connected via a pipeline to the first solenoid valve 26 of the rotating connecting cover 11, and the outlet is connected to the inlet of the vacuum pump 23. The outlet of the vacuum pump 23 is connected to the waste liquid collection tank 22.

[0032] The controller, which is a PLC or embedded industrial controller, is electrically connected to the first electric actuator 5, the second electric actuator 13, the drive motor 7, the first water pump 18, the second water pump 19, the vacuum pump 23, the first solenoid valve 26, the second solenoid valve 31, the hot air blower 32, the pH sensor, the conductivity sensor, the first pressure sensor 34, and the second pressure sensor 41, respectively. It is used to control the action sequence and operating parameters of each component and to receive sensor feedback signals to achieve closed-loop control.

[0033] II. Detailed Structure of Rotary Connecting Cover 11 The rotating connecting cover 11 is located between the first piston rod 6 and the hollow tube 10, and is a key component for realizing rotary sealing, waste liquid suction and hot air drying.

[0034] The rotating connecting cover 11 has a hollow cavity. The upper end of the hollow cavity is fixedly connected to the lower end of the first piston rod 6 by threads or a flange; the lower end of the hollow cavity is provided with a rotating sealing joint 27, the inner hole of which communicates with the upper end of the hollow tube 10, and the hollow tube 10 is coaxially aligned with the first piston rod 6. The rotating sealing joint 27 is equipped with a high-speed rotating dynamic sealing ring (such as a PTFE plug seal), which allows the hollow tube 10 to rotate freely relative to the rotating connecting cover 11 while maintaining a liquid seal.

[0035] A three-way pipe 28 is installed on the side wall of the hollow cavity. A first solenoid valve 26 is installed on the first branch pipe 29 of the three-way pipe 28. The outlet of the first solenoid valve 26 is connected to the inlet of the flow tank of the waste liquid collection and detection system via a pipeline. A second solenoid valve 31 is installed on the second branch pipe 30 of the three-way pipe 28. The inlet of the second solenoid valve 31 is connected to the outlet of a hot air blower 32 via a heat-resistant flexible hose. The hot air blower 32 is fixed on the movable base 1 and has a temperature control function (set temperature 60~80℃). III. Sensor wiring and signal transmission inside hollow tube 10 An inner tube 33 is coaxially fixed to the inner wall of the hollow tube 10. The inner tube 33 is made of stainless steel or PTFE, and its outer diameter is smaller than that of the inner diameter of the hollow tube 10, forming an annular gap for liquid (alkali solution or water) to pass through. The inner cavity of the inner tube 33 is used for wiring. A first pressure sensor 34 is installed at the lower end of the inner tube 33 (near the brush head 8). The probe of the first pressure sensor 34 extends out of the bottom of the inner tube 33 and is used to detect the pressure signal when the brush head 8 contacts the bottom of the crucible.

[0036] The signal and power lines of the first pressure sensor 34 run upwards along the inner cavity of the inner tube 33, extending to a position near the bottom of the rotary sealing joint 27, and then exit through a wire hole on the side wall of the hollow tube 10. A rotor 35 with a slip ring assembly is fixedly mounted on the side wall of the hollow tube 10, and the wires extending through it are welded or crimped to the terminals of the rotor 35. A stator 36 with a slip ring assembly is fixedly mounted on the stationary housing of the rotary sealing joint 27 (i.e., the lower part of the rotary connecting cover 11). The brushes of the stator 36 slide in contact with the conductive rings of the rotor 35, and the leads of the stator 36 are electrically connected to the controller. The slip ring assembly uses a through-hole conductive slip ring with an IP67 protection rating, a stainless steel housing, gold-plated contacts, and six channels (2 power channels + 4 signal channels).

[0037] To protect the first pressure sensor 34, a corrosion-resistant rubber ring 37 is provided at the bottom of the hollow tube 10. The length of the rubber ring 37 is slightly longer than the length of the first pressure sensor 34. A round hole is provided on the side wall of the rubber tube for pumping liquid and allowing air to pass through.

[0038] IV. Guiding Anti-rotation Structure The mounting platform 9 has four round rods 38 arranged in a square array (i.e., four rods evenly distributed around the central axis). The four round rods 38 pass upwards through four corresponding guide holes on the mounting base 4. A first linear bearing 39 is fixed inside each guide hole, and the round rods 38 slide against the first linear bearing 39. The upper ends of the round rods 38 protrude above the mounting base 4. The housing of the drive motor 7 is fixed to the central hole of the mounting platform 9 via a flange or an embedded method. A cross bracket 40 is fixed to the lower end of the first piston rod 6, and the four ends of the cross bracket 40 are fixedly connected to the four round rods 38 respectively.

[0039] When the first piston rod 6 extends or retracts, it simultaneously drives the four round rods 38 to rise and fall synchronously via the cross bracket 40. The round rods 38 are guided by the first linear bearing 39, which in turn drives the mounting platform 9 and the drive motor 7 fixed on it to rise and fall as a whole. Due to the circumferential constraint of the four round rods 38, the mounting platform 9 and the motor housing are reliably prevented from rotating, ensuring that the motor stator will not rotate due to counter-torque.

[0040] V. Independent lifting and clamping force control of sealing cover 12 Four second electric push rods 13 are evenly arranged around the housing of the drive motor 7, and the housing is fixed to the mounting platform 9 by screws. A second pressure sensor 41 is installed at the bottom of the second piston rod 14 of each second electric push rod 13. The second pressure sensor 41 is a spoke-type or S-type tension and compression sensor, and its lower end is connected to the upper end face of the sealing cover 12 through a ball joint or flexible connector.

[0041] The sealing cover 12 is bowl-shaped and made of alkali-resistant stainless steel or PTFE composite material. A 5mm thick alkali-resistant rubber gasket is adhered to the inner wall of the sealing cover 12. A linear rotary bearing 15 is installed in the central through-hole of the sealing cover 12. The inner ring of the linear rotary bearing 15 slides with the first piston rod 6, and the outer ring is fixed to the sealing cover 12. Fluororubber dustproof sealing rings are installed on the upper and lower end faces of the linear rotary bearing 15.

[0042] The controller reads the pressure values ​​of the four second pressure sensors 41 and controls the extension and retraction of the four second electric push rods 13 respectively through the PID algorithm, so that the pressing force of the sealing cover 12 on the furnace mouth end face is uniform and controllable (usually set to 50~200N), avoiding sealing failure or furnace mouth damage due to uneven load.

[0043] VI. Brush head 8-structure The brush head 8 includes a crucible side wall brushing section and a crucible bottom brushing section.

[0044] Sidewall cleaning section: Three first mounting rings 42 are spaced apart along the axial direction of the hollow tube 10 (the actual number can be increased or decreased according to the crucible depth). Each first mounting ring 42 is fixed to the outer wall of the hollow tube 10 by welding. Eight support rods 43 are uniformly welded circumferentially to the sidewall of the first mounting ring 42. The support rods 43 are provided with shoulders or nuts to limit the position of the springs 44. Compression springs 44 are sleeved on the support rods 43. The sidewall cleaning section also includes multiple arc-shaped support plates 45. Alkali-resistant bristles 46 are pasted on the outer arc surface of each support plate 45. Multiple through holes are opened in the vertical direction on the inner arc surface of the support plate 45. The number and position of the through holes correspond to the multiple support rods 43 in the same vertical projection direction. The support rods 43 pass through the through holes on the support plates 45, and the support plates 45 can slide radially along the support rods 43. The elastic force of the springs 44 keeps the support plates 45 and the bristles 46 pressed against the inner wall of the crucible at all times, adapting to crucibles of different diameters.

[0045] Bottom cleaning section: The second support ring 47 is fixed to the lowest end of the hollow tube 10 or below the side wall cleaning section. Four to six arc-shaped rods 48 are welded or screwed circumferentially to the side wall of the second support ring 47. The arc-shaped rods 48 are made of elastic stainless steel wire or spring steel 44, and their curvature is adapted to the shape of the crucible bottom (hemispherical or flat). Alkali-resistant bristles 46 are adhered to the arc-shaped rods 48, pointing towards the bottom of the crucible. A rubber ring 37 is located at the center of the bottom cleaning section. A circular rubber sieve plate 49 is provided at the bottom of the rubber ring 37, and alkali-resistant bristles 46 are provided on the rubber sieve plate 49.

[0046] VII. Online monitoring of waste liquid The suction path of the waste liquid collection and detection system is as follows: liquid in the crucible → inner cavity of the hollow tube 10 → hollow cavity of the rotating connecting cover 11 → first solenoid valve 26 → flow cell → vacuum pump 23 → waste liquid collection tank 22. When the liquid flows through the flow cell, the pH sensor and conductivity sensor continuously collect data and transmit it to the controller. The controller has preset pH thresholds (e.g., 6.5~7.5) and conductivity thresholds (e.g., ≤50μS / cm, corresponding to a silicate concentration lower than the set value). When the actual detected value exceeds the threshold range, the controller determines that the cleaning is not up to standard and automatically repeats the alkaline washing or rinsing process; when both pH and conductivity are within the threshold range and remain stable for more than 10 seconds, the cleaning is deemed qualified.

[0047] VIII. Control System, its Connections, and Component Selection 1. Overall Architecture of Controller and Electrical Connections The controller uses a programmable logic controller or an embedded industrial controller, integrated into the electrical control cabinet on the mobile base 1. The electrical control cabinet has an IP65 protection rating, is made of stainless steel, and has a waterproof cable connector at the cable inlet.

[0048] The input terminal of the controller is electrically connected to the following sensors: First pressure sensor 34 (analog input); Each second pressure sensor 41 (analog input); pH sensor (RS485 digital signal input); Conductivity sensor (RS485 digital signal input); Encoder signal line (pulse input) of the first electric push rod 5; The limit switch signal line (switch input) of the second electric push rod 13; The inlet pressure switch signal line (switching input) of vacuum pump 23; The liquid level sensor signal line (analog input) of the waste liquid collection tank 22. The liquid level sensor signal lines (analog input) for alkaline washing solution container 16 and clean water container 17.

[0049] The output of the controller is electrically connected to the following actuator: The servo driver of the first electric linear actuator 5 (controlled by pulse / direction or bus). Servo drivers for each of the second electric push rods 13 (controlled via bus); The motor driver for drive motor 7 (controlled via PWM or bus); AC contactor (switching output) of the first water pump 18; AC contactor (switching output) for the second water pump 19. AC contactor (switching output) for vacuum pump 23; The electromagnetic coil of the first solenoid valve 26 (switching output). The electromagnetic coil of the second solenoid valve 31 (switching output). The SSR solid-state relay control terminal (switching quantity or PWM output) of the hot air blower 32.

[0050] All connection cables between the controller and all sensors and actuators are made of oil-resistant and corrosion-resistant shielded cables. Signal lines and power lines are wired separately, and magnetic rings or filter capacitors are installed at both ends of the signal lines to suppress electromagnetic interference.

[0051] 2. Controller (PLC) Selection The controller uses a Siemens S7-1200 series programmable logic controller (PLC), with a CPU model of 1214CDC / DC / DC, featuring 14 digital inputs, 10 digital outputs, and 2 analog input channels. To withstand the corrosive gases of the alkaline washing environment, the controller circuit board is coated with a conformal coating (moisture-proof, salt spray-proof, and mildew-proof). The extended analog input module uses an SM1231AI8×13bit design to connect analog signals from the first pressure sensor 34 and the second pressure sensor 41. The controller communicates with each servo driver via a Profinet bus to achieve synchronous control.

[0052] 3. Selection of the first electric actuator 5 and the second electric actuator 13 (servo cylinder) The first electric push rod 5 and the second electric push rod 13 adopt HEB series servo electric cylinders (Guangdong Lianhua HEB125 series). The first electric push rod 5 is mainly responsible for the lifting and lowering of the brush head 8, with a stroke range of 10-2000mm (customized according to furnace depth, typical value is 1000mm), a maximum operating speed of 500mm / s, and a maximum thrust of 8000N (approximately 800KG). It uses a ball screw drive and has a built-in absolute encoder, with a positioning accuracy of ±0.05mm. There are four second electric push rods 13, evenly arranged around the drive motor 7, used to drive the lifting and lowering of the sealing cover 12 and to press the seal. Each push rod has a thrust of 500N (total pressing force approximately 2000N), a stroke of 100mm, and a positioning accuracy of ±0.1mm.

[0053] The controller 8 communicates with the drivers of each servo electric cylinder via the Profinet bus, reads the real-time position feedback from the encoder, and issues position and speed commands according to the set program.

[0054] 4. Drive Motor Selection The drive motor 7 adopts an MSMF series hollow shaft servo motor. The motor has a rated speed of 500 rpm, a rated torque of 15 N·m, a rated power of approximately 800 W, and an IP67 protection rating. The rotor 35 has a hollow structure, and the inner wall of the hollow tube 10 is lined with a stainless steel inner tube 33. The stator 36 housing is fixed to the mounting platform 9, and the hollow tube 10 (i.e., the shaft of the motor rotor 35) is directly connected to the brush head 8, driving the brush head 8 to rotate.

[0055] The controller communicates with the motor driver of the drive motor 7 via RS485 or CAN bus, sends speed commands, and reads the actual speed feedback.

[0056] 5. Selection of the first water pump 18 and the second water pump 19 The first pump 18 is used to pump alkaline washing solution, and the second pump 19 is used to pump clean water. Both are stainless steel vertical multistage centrifugal pumps, model CDLF2-22 (Southern Pump Industry). The flow parts are made of 316L stainless steel, with a flow rate of 2 m³ / h, a head of 22 m, a power of 0.55 kW, and a power supply of AC380V. 316L stainless steel can withstand strong alkaline conditions with a pH value up to 14 (maximum temperature 60℃, below the 316L corrosion resistance limit of 80℃).

[0057] The controller controls the start and stop of the first water pump 18 and the second water pump 19 respectively through AC contactors. The contactor coils are driven by the digital output terminal of the controller.

[0058] 6. Vacuum Pump 23 Selection Vacuum pump 23 is used to pump waste liquid in crucible. It is a dry screw vacuum pump 23, model BSV40, with ultimate vacuum of 0.1mbar, pumping speed of 40m³ / h, motor power of 1.5kW, and an integral anti-corrosion coating. The parts in contact with the medium are coated with Teflon, and the flow parts are made of 316L stainless steel. It is suitable for pumping alkaline liquids and gas-liquid mixtures.

[0059] A cooling buffer tube (made of stainless steel, about 500mm in length) is installed before the inlet of vacuum pump 23 to cool the gas temperature entering the pump body and prevent high-temperature gas from damaging the pump body seal.

[0060] The controller controls the start and stop of the vacuum pump 23 through an AC contactor, and at the same time controls the opening and closing sequence of the first solenoid valve 26 through a digital output terminal, so that the suction action is synchronized with the operation of the vacuum pump 23.

[0061] 7. Selection of Detection Device 24 (pH Sensor and Conductivity Sensor) The detection device 24 includes a flow cell and its internal pH sensor and conductivity sensor, which are fixed to the inlet pipe of the waste liquid collection tank 22.

[0062] pH sensor: Selected HachHC57 series pH electrode, measuring range 0~14pH, accuracy ±0.01pH, adopts special glass sensitive membrane, resistant to strong acids and alkalis, specially designed reference system effectively prevents electrode poisoning, suitable for online pH monitoring in harsh industrial conditions, operating temperature 0~100℃, built-in Pt1000 temperature sensor for temperature compensation.

[0063] Conductivity sensor: Uses 8953 stainless steel conductivity electrode, 316L stainless steel shell, resistant to strong acids and alkalis, conductivity cell constant K=0.01cm⁻¹ (suitable for ultrapure water and low conductivity liquid measurement), measurement range 0.02~20μS / cm, accuracy ±1%FS, supports RS485 Modbus RTU output.

[0064] Flow cell: Made of PTFE material, both the inlet and outlet are equipped with 1 / 4" NPT internal threads. The pH sensor and conductivity sensor are installed on the reserved interface of the flow cell through the threads. The sensor probe is immersed in the flowing liquid. The installation interface is equipped with an O-ring seal.

[0065] The RS485 interfaces of the pH sensor and conductivity sensor are connected to the CM1241 RS485 communication module of the controller via shielded twisted-pair cables. The controller polls and reads the measured values ​​using the Modbus RTU protocol.

[0066] 8. Selection of the first pressure sensor 34 and the second pressure sensor 41 The first pressure sensor 34 is installed at the lower end of the inner tube 33 to detect the contact pressure between the brush head 8 and the bottom of the crucible. It is a miniature S-type tension and compression sensor with a range of 0~50N, an accuracy of ±0.5%FS, a stainless steel elastomer material, a diameter of 12mm, a height of 20mm, and an output of 0~10V analog voltage signal.

[0067] There are four second pressure sensors 41, which are installed between the bottom of the second piston rod 14 of each second electric push rod 13 and the sealing cover 12. They are used to detect the pressing force of the sealing cover 12 on the furnace opening. They are spoke-type tension and pressure sensors with a range of 0~500N, an accuracy of ±0.5%FS, strong resistance to lateral force, and output of 4~20mA current signal.

[0068] All analog signal lines of the pressure sensors are connected to the SM1231 analog input module of the controller using shielded cables, and the shielding layer of the signal lines is grounded at one end on the controller side.

[0069] 9. Slip Ring Assembly Selection The slip ring assembly is used to transmit the signal and power supply of the first pressure sensor 34 on the rotating part (hollow tube 10) to the stationary controller. It adopts a through-hole conductive slip ring, model SRT012-06P-IP67 (Merfolon or similar product), with a through-hole diameter of 12mm, 6 channels (2 power supply + 4 signal), protection level of IP67, housing material of stainless steel, gold-plated contacts (gold-gold contact), contact resistance ≤20mΩ, insulation resistance ≥500MΩ, applicable speed range of 0~300rpm, and corrosion resistance suitable for alkaline washing environment.

[0070] The rotor 35 of the slip ring assembly is fixed to the side wall of the hollow tube 10 and rotates together with the hollow tube 10; the stator 36 is fixed to the stationary outer shell of the rotating connecting cover 11. The power line and signal line of the first pressure sensor 34 are led out from the inner cavity of the inner tube 33 and connected to the terminal of the rotor 35 through the wire hole. The lead wire of the stator 36 is connected to the analog input module of the controller.

[0071] 10. Selection of Hot Air Blower 32 Hot air blower 32 is used in the drying process. It is an HBO-3A industrial hot air blower 32 with a heating power of 3kW, an adjustable outlet air temperature of 50~350℃, a maximum air volume of 5m³ / min, a K-type thermocouple at the air outlet for temperature control, PID temperature control accuracy of ±2℃, built-in stainless steel heating element, and a 304 stainless steel outer shell that is corrosion resistant. The whole machine has an IP54 protection rating.

[0072] The controller controls the heating start and stop of the hot air blower 32 through an SSR solid-state relay, and at the same time controls the opening and closing of the second solenoid valve 31 through a digital output terminal, so as to achieve coordinated control of purging and heating.

[0073] 11. Solenoid Valve Selection The first solenoid valve 26 is located on the first branch pipe 29 of the three-way pipe 28 and is used to control the on / off of waste liquid suction; the second solenoid valve 31 is located on the second branch pipe 30 of the three-way pipe 28 and is used to control the on / off of hot air. Both solenoid valves are explosion-proof two-way solenoid valves, model ASCO8210G094 series, with valve body material of 316L stainless steel, nominal diameter of 15mm (1 / 2"), working pressure range of 0~1.0MPa, sealing material of PTFE and fluororubber (FKM), coil protection rating of IP67, voltage of DC24V, and are suitable for controlling strong alkaline liquids and high-temperature gases.

[0074] The controller directly drives the solenoid valve coil to switch on and off via a digital output terminal (transistor output, DC24V, 0.5A). A freewheeling diode (1N4007) is connected in reverse parallel across the two ends of each solenoid valve coil to prevent the back electromotive force when the coil is de-energized from damaging the controller output port.

[0075] 12. Containers and piping for the alkaline washing solution and clean water supply system Both the alkaline washing solution container 16 and the clean water container 17 are made of PP polypropylene rotational molding tanks, equipped with vents and level gauge interfaces, resistant to NaOH strong alkali corrosion, and have a temperature range of 0~60℃.

[0076] Liquid level sensors are installed in both the alkaline washing solution container 16 and the clean water container 17. The selected sensors are MFE600E type submersible liquid level transmitters (microphone sensors), with a range of 0~1m, an output of 4~20mA, a probe material of 316L stainless steel, and a housing protection rating of IP68. The liquid level signal is connected to the analog input module of the controller 8 for low liquid level alarm and liquid supply interruption protection.

[0077] The inlets of the first water pump 18 and the second water pump 19 are equipped with filter screens (100-mesh stainless steel filter screens) between them and the alkaline washing solution container 16 and the clean water container 17 to prevent particulate matter from entering the pump body. The pump outlet is connected to the first inlet 20 and the second inlet 21 provided on the sealing cover 12 by an alkali-resistant hose (lined with PTFE and with a stainless steel braided mesh outer layer).

[0078] The entire tooling's power supply system uses a 380VAC three-phase five-wire connection, with power supplied to each motor, water pump, vacuum pump 23, hot air blower 32, etc., via the main circuit breaker and branch air switches in the electrical control cabinet. The controller and each sensor's DC24V power supply is provided by a Mean Well NDR-120-24 DIN rail switching power supply, with an input of 220VAC and an output of 24VDC / 5A.

[0079] IX. Work Process After the single crystal furnace completes the crystal pulling task, it is shut down and cooled according to the process specifications to reduce the furnace temperature to room temperature or a safe temperature (usually ≤50℃). The top of the single crystal furnace, including the flow guide tube, auxiliary chamber, and seed crystal cavity, is removed to fully expose the furnace opening. These components are typically connected to the main furnace chamber via flange bolts and can be removed manually or with lifting tools. Residue is cleaned from the flange end face of the furnace opening, and the sealing surface is inspected for damage to ensure that the subsequent sealing cover 12 fits well against the furnace opening end face.

[0080] Phase 1: Initial Preparation and Sealing Initial position: Both the first electric push rod 5 and the second electric push rod 13 are in the retracted state, and the cleaning component and the sealing cover 12 are in the highest position.

[0081] Moving and positioning: The operator pushes the tooling above the furnace opening of the single crystal furnace, aligns the center of the sealing cover 12 with the furnace opening, and locks the universal wheel 2.

[0082] The sealing cover 12 descends: The controller drives four second electric push rods 13 to extend, and the second piston rod 14 pushes the sealing cover 12 down until the rubber gasket contacts the furnace opening end face. The second pressure sensor 41 provides real-time pressure feedback. When the pressure reaches the set value (e.g., 100N), the descent stops and remains stationary. After this stage begins, the sealing cover 12 remains sealed throughout the entire cleaning process and does not rise or fall further.

[0083] Phase Two: Sidewall Cleaning Initial descent of brush head 8: The controller drives the first electric push rod 5 to extend at a medium speed (e.g., 50 mm / s). The first piston rod 6, through the cross bracket 40, the round rod 38, and the mounting platform 9, drives the entire cleaning component to descend. The first pressure sensor 34 monitors the axial pressure in real time. The moment the bottom of brush head 8 contacts the bottom of the crucible, the signal of the first pressure sensor 34 changes, the controller records the current position as the "bottom zero point," and immediately stops the descent.

[0084] Brush head 8 moves up to the starting point of the side wall: The controller drives the first electric push rod 5 to retract, raising the brush head 8 to the inner side of the top of the crucible (about 100~200mm away from the furnace opening), and the current position is recorded as the "top starting point".

[0085] Alkali washing of side walls (up and down repeatedly): The controller turns on the first water pump 18 and the drive motor 7. The alkaline washing solution is injected into the crucible from the alkaline washing solution container 16 through the first inlet 20 of the sealing cover 12. At the same time, the brush head 8 rotates at a set speed (such as 60~80 rpm).

[0086] The controller controls the first electric push rod 5 to slowly descend from top to bottom at a low speed (e.g., 20~30mm / s), while the brush head 8 rotates and descends, brushing the side wall of the crucible.

[0087] After reaching the bottom zero point (or approaching the bottom with a 10mm safety distance reserved), the controller controls the first electric push to reverse and rise from bottom to top at the same speed to the top starting point.

[0088] Repeat the above up-and-down motion 2 to 4 times (depending on the depth of the crucible and the degree of contamination) to ensure that every part of the sidewall is thoroughly scrubbed.

[0089] During the sidewall cleaning process, the first solenoid valve 26 and vacuum pump 23 can be opened intermittently to extract a small amount of waste liquid for online detection and monitor the cleaning progress.

[0090] Dynamic compensation of sealing pressure during sidewall cleaning: Since the mounting platform 9 is rigidly connected to the first piston rod 6 via the cross bracket 40 and four round rods 38, when the first electric push rod 5 drives the brush head 8 to move up and down, the mounting platform 9 will inevitably rise and fall synchronously with the first piston rod 6. This rising and falling motion will cause the second electric push rod 13 fixed below the mounting platform 9 and its connected sealing cover 12 to change position relative to the furnace opening in the same direction, thereby causing fluctuations in the clamping force between the sealing cover 12 and the furnace opening.

[0091] To eliminate the inevitable pressure fluctuations, the controller reads the real-time pressure values ​​of the four second pressure sensors 41 at a high frequency (e.g., once every 10ms). When the sealing clamping force is detected to be lower than the target value (e.g., 80N), the controller (8) immediately drives the four second electric push rods 13 to extend synchronously, so that the sealing cover 12 is pressed further against the furnace opening until the pressure is restored to the target range (e.g., 90~110N); when the clamping force is detected to be higher than the target value (e.g., 120N), the second electric push rods 13 are slightly retracted to avoid excessive pressure damaging the ceramic parts at the furnace opening.

[0092] The dynamic compensation process is executed in parallel with the lifting and lowering movement of the first electric push rod 5. Since the response speed (millisecond level) of the four second electric push rods 13 is much faster than the movement speed (second level) of the first electric push rod 5, it can be ensured that the pressing force of the sealing cover 12 on the furnace mouth is always maintained within the set error range during the entire side wall cleaning process. Thus, under the premise that the mechanical structure will inevitably cause position changes, the constant sealing pressure is achieved through active control.

[0093] Phase 3: Bottom Cleaning (Stationary Rotation) Brush head 8 positioned at the bottom: After the side wall cleaning is completed, the controller drives the first electric push rod 5 to lower the brush head 8 to the bottom cleaning position. At this time, the bristles 46 on the arc rod 48 of the bottom brushing part are in contact with the curved surface of the bottom of the crucible, and the pressure value fed back by the first pressure sensor 34 reaches the preset "bottom contact pressure" (e.g., 5~10N).

[0094] Bottom alkaline wash: The controller keeps the first water pump 18 running to replenish the alkaline washing solution and maintain the liquid level.

[0095] The brush head 8 rotates at a slightly lower speed (e.g., 30-50 rpm), but the first electric push rod 5 remains stationary, so that the brush head 8 stays at the bottom position for concentrated cleaning.

[0096] The duration of bottom cleaning is set according to the degree of deposition at the bottom of the crucible, and is usually 30 to 120 seconds.

[0097] Phase Four: Wastewater Discharge and Detection After the sidewalls and bottom are cleaned, the controller shuts off the first water pump 18 and opens the first solenoid valve 26 and vacuum pump 23 to pump all the waste alkaline solution in the crucible into the waste liquid collection tank 22. The pH and conductivity values ​​are recorded as the liquid flows through the flow tank. If the test values ​​are qualified, the rinsing step is initiated; if they are not qualified, the sidewall and bottom cleaning are automatically repeated (or only the bottom cleaning is repeated depending on the degree of exceedance).

[0098] Phase 5: Segmented rinsing (symmetrical to the alkaline washing process) Side wall rinsing: The controller closes the first solenoid valve 26 and turns on the second water pump 19, injecting clean water into the crucible. The brush head 8 rotates, and the first electric push rod 5 drives the brush head 8 to move back and forth from top to bottom and from bottom to top 2-3 times to rinse the side wall.

[0099] Bottom rinsing: Position brush head 8 at the bottom and keep it still while rotating for 30-60 seconds to thoroughly rinse the bottom.

[0100] Final extraction and testing: Open the first solenoid valve 26 and vacuum pump 23 to extract and test the rinse water. If the test is qualified, proceed to the drying step; if it fails, repeat the rinsing process.

[0101] Phase Six: Hot Air Drying After rinsing, the controller closes the first solenoid valve 26 and the second water pump 19, and turns on the second solenoid valve 31 and the hot air blower 32. Hot air is blown into the crucible through the rotating connecting cover 11 and the hollow tube 10. The brush head 8 rotates at a low speed (20~30 rpm), and the first electric push rod 5 slowly moves up and down once to evenly cover the side walls and bottom with hot air. The drying time is 3~5 minutes.

[0102] Phase Seven: Reset After drying is complete, the controller shuts off the hot air blower 32 and the second solenoid valve 31. The first electric push rod 5 is driven to retract in sequence (the brush head 8 rises to the highest position), and then the second electric push rod 13 is driven to retract (the sealing cover 12 rises). The operator unlocks the caster wheel 2 and moves the tooling away from the furnace opening.

[0103] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A sealing fixture for alkaline washing of a single crystal furnace, characterized in that, include: A mobile base (1) with a universal wheel (2) with locking function at the bottom; The bracket (3) is fixed on the movable base (1), and the upper end of the bracket (3) is provided with a mounting base (4) that extends horizontally beyond the movable base (1). The first electric push rod (5) is installed on the mounting base (4); The cleaning component is located below the mounting base (4) and is driven to rise and fall by the first piston rod (6) of the first electric push rod (5); The secondary lifting mechanism includes a mounting platform (9), a sealing cover (12), and a second electric push rod (13); the mounting platform (9) moves up and down synchronously with the cleaning component; the sealing cover (12) is located below the mounting platform (9); the second electric push rod (13) is mounted on the mounting platform (9) and is used to drive the sealing cover (12) to move up and down independently relative to the mounting platform (9); An alkaline washing solution and clean water supply system is installed on the movable base (1) and is used to supply alkaline washing solution and clean water into the sealing cover (12); The cleaning component includes a drive motor (7) and a brush head (8); the housing of the drive motor (7) is fixedly connected to the mounting platform (9), and the shaft of the drive motor (7) is a hollow tube (10); the upper end of the hollow tube (10) is rotatably and sealed to the first piston rod (6) through a rotating connecting cover (11); the brush head (8) is fixed to the lower end of the hollow tube (10); A waste liquid collection and detection system, connected to the rotary joint, is used to extract liquid from the crucible and detect its electrical signal. The controller is used to control the sequence of actions and operating parameters of each component.

2. The single-crystal furnace alkaline washing sealing fixture according to claim 1, characterized in that, The rotating connecting cover (11) includes: the rotating connecting cover (11) having a hollow cavity; The upper end of the hollow cavity is fixedly connected to the first piston rod (6); The lower end of the hollow cavity is provided with a rotary sealing joint (27), which is connected to the upper end of the hollow tube (10), and the hollow tube (10) is coaxially aligned with the first piston rod (6); A three-way pipe (28) is provided on the side wall of the hollow cavity. A first solenoid valve (26) is provided on the first branch pipe (29) of the three-way pipe (28). The first branch pipe (29) is connected to the waste liquid collection and detection system.

3. The single-crystal furnace alkaline washing sealing fixture according to claim 2, characterized in that, The waste liquid collection and detection system includes: Waste liquid collection tank (22) has a drain valve (25) on its lower side wall. Vacuum pump (23); The detection device (24) includes a flow cell having an inlet and an outlet; The flow cell is equipped with a pH sensor and a conductivity sensor; The pH sensor is used to measure the pH value of the liquid flowing through it; The conductivity sensor is used to measure the conductivity value of the liquid flowing through it, and is used to characterize the amount of silicon residue. The outlet of the first solenoid valve (26) is connected to the inlet of the flow tank, the outlet of the flow tank is connected to the inlet of the vacuum pump (23), and the outlet of the vacuum pump (23) is connected to the waste liquid collection tank (22). During suction, the liquid in the crucible flows sequentially through the first solenoid valve (26), the flow cell, and the vacuum pump (23) before entering the waste liquid collection tank (22). The pH sensor and the conductivity sensor output detection signals in real time as the liquid flows through.

4. The single-crystal furnace alkaline washing sealing fixture according to claim 2, characterized in that, The three-way pipe (28) also has a second branch pipe (30), on which a second solenoid valve (31) is provided. The second solenoid valve (31) is connected to a hot air blower (32) for blowing hot air into the crucible to dry the moisture.

5. The single-crystal furnace alkaline washing sealing fixture according to claim 2, characterized in that, The hollow tube (10) has an inner tube (33) on its inner wall, and the inner tube (33) extends along the axial direction of the hollow tube (10). The lower end of the inner tube (33) is provided with a first pressure sensor (34) for detecting the pressure signal when the brush head (8) contacts the bottom of the crucible; The signal line and power line of the first pressure sensor (34) run from the inside of the inner tube (33), extend to a position near the bottom of the rotary sealing joint (27), and then pass through the side wall of the hollow tube (10); The hollow tube (10) has a rotor (35) with a slip ring assembly on its side wall, and the rotary sealing joint (27) has a stator (36) with a slip ring assembly on its stationary part. The signal line and power line are electrically connected to the rotor (35) of the slip ring assembly, and the stator (36) of the slip ring assembly is electrically connected to the controller; the slip ring assembly is used to transmit the signal and power supply of the sensor on the rotating hollow tube (10) to the stationary controller.

6. The alkaline washing and sealing fixture for a single crystal furnace according to claim 1, characterized in that, The mounting platform (9) has four round rods (38) arranged in a square array. The four round rods (38) pass upward through the mounting base (4). A first linear bearing (39) is provided at the contact point between the round rod (38) and the mounting base (4). The first linear bearing (39) is fixedly connected to the mounting base (4), and the round rod (38) and the first linear bearing (39) are in sliding fit. The housing of the drive motor (7) is embedded and fixed on the mounting platform (9); A cross bracket (40) is fixed on the first piston rod (6), and the four ends of the cross bracket (40) are respectively fixedly connected to the upper ends of the four round rods (38).

7. The single-crystal furnace alkaline washing sealing fixture according to claim 6, characterized in that, The four second electric push rods (13) are arranged circumferentially around the drive motor (7); Each of the second electric push rods (13) has a second pressure sensor (41) at the bottom of the second piston rod (14), and the other end of the second pressure sensor (41) is connected to the upper end face of the sealing cover (12). The sealing cover (12) is bowl-shaped, and a rubber gasket is provided on its inner wall; A linear rotary bearing (15) is provided at the center of the sealing cover (12). The linear rotary bearing (15) is sleeved on the first piston rod (6) to realize the relative rotation and relative axial sliding between the sealing cover (12) and the first piston rod (6). A sealing ring is provided on the linear rotary bearing (15). The second pressure sensor (41) is electrically connected to the controller and is used to detect the pressure applied to the sealing cover (12) by each of the second electric push rods (13) in real time, so as to control the clamping force between the sealing cover (12) and the crucible furnace opening.

8. The alkaline washing and sealing fixture for a single crystal furnace according to claim 1, characterized in that, The brush head (8) includes a crucible sidewall brushing section and a crucible bottom brushing section; The sidewall brushing section includes: a plurality of first mounting rings (42) spaced apart along the axial direction of the hollow tube (10), each of the first mounting rings (42) having a plurality of radially extending support rods (43) circumferentially arranged on the sidewall of the sidewall, each of the support rods (43) being fitted with a spring (44); and a plurality of support plates (45), each of the support plates (45) having bristles (46) pointing toward the inner wall of the crucible, the support plates (45) having a plurality of through holes opened in the vertical direction, the through holes being slidably engaged with the plurality of support rods (43) in the same vertical projection direction, the elastic force of the springs (44) causing the support plates (45) and the bristles (46) to always press against the inner wall of the crucible; The bottom brushing section includes: a second support ring (47) fixed to the lower end of the hollow tube (10) or below the side wall brushing section; and multiple arc-shaped rods (48) circumferentially arranged on the side wall of the second support ring (47), the arc-shaped rods (48) being provided with bristles (46) pointing to the bottom of the crucible, and the curvature of the arc-shaped rods (48) matching the shape of the bottom of the crucible when the bottom brushing section rotates with the hollow tube (10).

9. The alkaline washing and sealing fixture for a single crystal furnace according to claim 1, characterized in that, The alkaline washing solution and clean water supply system includes: An alkaline washing solution container (16) and a clean water container (17) are respectively mounted on the movable base (1); The first water pump (18) has its inlet connected to the alkaline washing solution container (16) and its outlet connected to the first inlet (20) provided on the sealing cover (12) to pump the alkaline washing solution into the crucible; The second water pump (19) has its inlet connected to the clean water container (17) and its outlet connected to the second inlet (21) provided on the sealing cover (12) to pump clean water into the crucible.

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