A device for fusing a zone-melted silicon ingot

Abstract

The utility model discloses a kind of zone melting method square silicon core welding devices, it is related to square silicon core welding technical field, the zone melting method square silicon core welding device, including sealed shell, the side of sealed shell is provided with sealing door, sealing door is slid in the slide way of sealed shell, a pair of positioning clamps for fixed and alignment two section square silicon core, heating mechanism for heating silicon core butt joint area and atmosphere protection mechanism are equipped in sealed shell, a pair of positioning clamps are slid in the adjusting track of the inside setting of sealed shell, heating mechanism is located between a pair of positioning clamps, atmosphere protection mechanism is communicated with sealed shell, and it is common to constitute a closed working environment. The utility model is through integrated high-precision multistage adjusting positioning clamp, closed loop pressure control, movable heating disc and multistage purification atmosphere protection function, realize the accurate centering of square silicon core in clean stable environment, uniform welding and full-process automation operation, improve the welding quality and industrial applicability.

Description

Technical Field

[0001] This utility model relates to the field of square silicon core welding technology, and in particular to a square silicon core welding device using the zone melting method. Background Technology

[0002] In the fabrication of polycrystalline and monocrystalline silicon, the silicon core, as a crucial conductive and supporting structure, often requires a welding process to connect multiple square silicon core segments into a longer continuous structure to meet the requirements of reduction furnaces or zone melting furnaces. Traditional silicon core welding often employs manual alignment with a fixed heating device, which suffers from low docking accuracy, uncontrollable axial pressure, and susceptibility to oxidation and contamination. This results in insufficient strength and uneven resistance in the welded area, and even cracks or necking, severely impacting the quality and efficiency of subsequent crystal growth.

[0003] Although existing welding equipment has partially incorporated mechanical clamping and inert gas protection, it still has significant shortcomings in terms of positioning accuracy, pressure feedback, atmosphere purity, and heating uniformity. For example, the clamping adjustment has limited freedom, making it difficult to achieve micron-level alignment; pressure is applied based on experience, lacking real-time monitoring and closed-loop control; and the protective gas is not deeply purified, with residual oxygen and moisture easily reacting with silicon at high temperatures to generate oxide defects. Utility Model Content

[0004] This utility model provides a zone melting method for welding square silicon cores, including a sealing shell with a sealing door on one side. The sealing door slides in a slide rail on the sealing shell. Inside the sealing shell are a pair of positioning clamps for fixing and aligning two square silicon cores, a heating mechanism for heating the silicon core docking area, and an atmosphere protection mechanism. The pair of positioning clamps slide relative to each other in an adjustment track inside the sealing shell. The heating mechanism is located between the pair of positioning clamps. The atmosphere protection mechanism is connected to the sealing shell, together forming a closed working environment.

[0005] Preferably, the positioning fixture includes a sliding block that slides within an adjusting track. An adjusting track one is fixedly provided on one side of the sliding block. An adjusting track two is slidably provided within the adjusting track one. An adjusting track three is slidably provided within the adjusting track two. A positioning block is slidably provided within the adjusting track three. Two sets of positioning grooves are provided within the positioning block. A fixing block is slidably provided within a limiting groove provided on the side wall of the positioning block.

[0006] Preferably, a symmetrical electric push rod is provided on one side of the positioning block, the piston end of the electric push rod is connected to one side of the fixing block, and a "V" shaped groove is opened on the inner side of the fixing block, and a pressure sensor is embedded in the inner wall of the fixing block.

[0007] Preferably, a lead screw is rotatably installed inside the first adjusting rail, and the lead screw is threadedly connected to the bottom of the second adjusting rail. A lead screw is rotatably installed inside the second adjusting rail, and the lead screw is threadedly connected to one side of the third adjusting rail. A lead screw is rotatably installed inside the third adjusting rail, and the lead screw is threadedly connected to the positioning block. The lead screws 1, 2, and 3 are driven by their respective motors.

[0008] Preferably, a bidirectional lead screw is rotatably installed inside the adjusting track, with both ends of the bidirectional lead screw threadedly connected to two sets of sliding blocks, and one end of the bidirectional lead screw connected to the output shaft of the motor.

[0009] Preferably, the heating mechanism includes a pair of side rails respectively disposed on the inner wall of the sealed shell, a heating plate is slidably disposed between the two sets of side rails, and two sets of welding rings are disposed inside the heating plate.

[0010] Preferably, a lead screw four is rotatably disposed within one of the side rails, the lead screw four being threadedly connected to one side of the heating plate, and the lead screw four being driven by a motor.

[0011] Preferably, the upper end of the sealing shell has a cavity, a vacuum pump is installed in the cavity, and the air extraction port of the vacuum pump is connected to a pipe extending into the interior of the sealing shell.

[0012] Preferably, the atmosphere protection mechanism includes an argon cylinder disposed on one side of the sealed shell. The outlet of the argon cylinder is connected to a gas purification mechanism via a pipe. A pressure reducing valve is disposed on the pipe. The outlet of the gas purification mechanism is connected to a gas supply pipe that extends into the interior of the sealed shell. A precision flow controller and a pneumatic valve are disposed on the gas supply pipe. A gas guide plate is disposed on the top of the sealed shell.

[0013] Preferably, the gas purification mechanism includes a shell with an air inlet and an air outlet at both ends, and an oxygen absorption layer, a molecular sieve adsorption layer, and a particle filter layer are sequentially arranged inside the shell.

[0014] This utility model provides a zone melting method for welding square silicon cores, which, compared with the prior art, offers the following advantages:

[0015] 1. This utility model achieves high-precision alignment of two square silicon cores in three-dimensional space by setting a sliding positioning fixture and a multi-level fine-tuning function. Each positioning fixture is driven by a bidirectional lead screw to move as a whole along the adjustment track. With the help of the internal multi-level lead screw transmission mechanism, it can be adjusted step by step, so that the positioning groove at the clamping end can achieve fine displacement, ensuring accurate docking of the two silicon core end faces. At the same time, the electric push rod on the positioning block drives the fixing block with a "V" shaped groove to press the silicon core. Combined with the embedded pressure sensor to provide real-time feedback of the clamping force, a closed-loop control is formed to achieve stable and controllable axial pressure loading. This structure effectively ensures the tight fit and coaxiality of the docking surface, avoids silicon core damage caused by uneven force or overpressure, and improves the stability and consistency of the welding.

[0016] 2. This utility model integrates a movable heating plate and atmosphere to ensure that the welding process is carried out in a clean and stable environment. The heating plate can slide up and down along the side rail, so that the internal heating element is precisely positioned to the docking area to achieve uniform zone melting scanning heating. At the same time, the protective gas is treated by the purification mechanism to effectively remove oxygen, moisture and particulate impurities, and then evenly distributed in the welding area through the guide structure to prevent oxidation and contamination. Vacuum and gas control work together to complete the full replacement of the cavity and maintain the atmosphere, ensuring a highly pure internal environment. The entire device realizes the integrated operation of the entire process from precise positioning and pressure control to heating and atmosphere management. It is highly efficient, has good repeatability, and is suitable for industrial application scenarios of continuous and automated welding of high-purity silicon materials. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0019] Figure 2 This is a schematic diagram of the internal structure of the sealing shell according to an embodiment of the present utility model;

[0020] Figure 3 This is a schematic diagram of the positioning clamp and heating mechanism according to an embodiment of the present utility model;

[0021] Figure 4 This is a schematic diagram of the structure of the adjustment track and other components according to an embodiment of the present utility model;

[0022] Figure 5 This is a schematic diagram of the positioning fixture structure according to an embodiment of the present utility model;

[0023] Figure 6 This is a schematic diagram showing the disassembled structure of the positioning clamp according to an embodiment of the present utility model;

[0024] Figure 7 This is a schematic diagram showing the disassembled structure of the heating mechanism according to an embodiment of the present utility model;

[0025] Figure 8 This is a cross-sectional schematic diagram of the gas purification mechanism according to an embodiment of the present invention.

[0026] Figure label:

[0027] 1. Sealing shell; 2. Sealing door; 3. Slide rail; 4. Adjusting track; 41. Two-way lead screw; 5. Positioning clamp; 51. Sliding block; 52. Adjusting rail one; 53. Lead screw one; 54. Adjusting rail two; 55. Lead screw two; 56. Adjusting rail three; 57. Lead screw three; 58. Positioning block; 581. Positioning groove; 582. Fixing block; 583. Pressure sensor; 584. Electric push rod; 6. Side rail; 61. Lead screw four; 62. Heating plate; 63. Welding ring; 7. Gas guide plate; 8. Vacuum pump; 9. Argon cylinder; 10. Pressure reducing valve; 11. Gas purification mechanism; 111. Outer shell; 112. Oxygen absorption layer; 113. Molecular sieve adsorption layer; 114. Particle filter layer; 12. Precision flow controller; 13. Gas delivery pipe. Detailed Implementation

[0028] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0029] Please refer to Figures 1-8 This utility model provides a zone melting method for welding square silicon cores, including a sealing shell 1. The sealing shell 1 is a rectangular stainless steel cavity, preferably made of 316L stainless steel. The inner surface is electrolytically polished to reduce the gas evolution rate. A rectangular opening is provided on one side of the sealing shell 1, and a slide 3 is provided on its edge. A high-temperature resistant elastic sealing gasket is embedded in the slide 3. The sealing door 2 is inserted into the slide 3 by sliding and can be opened or closed by horizontal pushing and pulling. When the sealing door 2 is closed, the sealing gasket is deformed by pressure and fills the gap between the door and the shell to achieve airtight sealing and ensure that the cavity can withstand vacuum and positive pressure conditions.

[0030] In addition, a temperature measurement window can be provided on the top or side wall of the sealing shell 1. An infrared thermometer is installed at the window. The infrared thermometer collects the temperature signal of the melting zone in real time and transmits the data to the main control system at a sampling frequency of ≥100Hz to ensure dynamic response capability to temperature changes.

[0031] The main control system adopts a PLC controller, preferably a Siemens S7-1200 series programmable logic controller, which integrates a multi-channel sensor signal acquisition module to receive real-time data from devices such as infrared thermometers, pressure sensors 583, displacement sensors linked with various lead screw motor encoders, and precision flow controllers 12. The sampling frequency is not less than 100Hz to ensure high-precision synchronous acquisition of various process parameters.

[0032] The PLC controller 15 is connected to a touch screen human-machine interface and is installed on the outside of the equipment in an easily accessible position to realize human-machine interaction. Operators can preset welding process parameters through the touch screen, including heating power, scanning speed, target pressure, holding time, gas flow rate, etc. It also supports the storage of more than 100 sets of process recipes, which facilitates the quick recall and switching of different specifications of silicon cores.

[0033] During operation, the touch screen displays the temperature-time curve, pressure change curve, displacement trajectory, and gas flow status in real time, facilitating operators to monitor the entire welding process. The system has multiple alarm functions, including over-temperature, over-pressure, abnormal gas pressure, and vacuum failure, with an alarm response time of ≤1 second. It triggers audible and visual alarms and automatically executes safety protection actions, such as cutting off the heating power supply, shutting off the gas circuit, and starting the cooling system.

[0034] The sealing shell 1 is equipped with two sets of symmetrically arranged positioning clamps 5, which are used to clamp and precisely align the two square silicon cores to be welded. Each set of positioning clamps 5 includes a sliding block 51 that is slidably installed on the bottom adjustment rail 4 inside the sealing shell 1. The adjustment rail 4 is a linear guide rail structure, and a bidirectional lead screw 41 is rotatably installed inside. The two ends of the lead screw 41 have opposite threads and are threaded to the two sliding blocks 51 on both sides respectively. One end of the bidirectional lead screw 41 is connected to a servo motor, which drives the two sliding blocks 51 to move synchronously towards each other or away from each other by forward and reverse rotation, so as to achieve coarse adjustment of the overall spacing between the two silicon cores.

[0035] An adjustment rail 52 is fixed on the sliding block 51, and a lead screw 53 is rotatably installed inside the sliding block 51. The lead screw 53 is threaded to the bottom of the adjustment rail 54. The adjustment rail 54 has a lead screw 55 inside, which is threaded to one side of the adjustment rail 56. The adjustment rail 56 has a lead screw 57 inside, which is threaded to the positioning block 58. The three sets of lead screws are driven by independent stepper motors, forming a multi-level micro-adjustment mechanism in the X, Y, and Z axes. This mechanism can realize nanometer-level displacement adjustment of the positioning block 58 in three-dimensional space, ensuring high-precision alignment of the two silicon core end faces and controlling the coaxiality error within a very small range.

[0036] The positioning block 58 has two sets of opposing "V"-shaped positioning grooves 581 at its center, which are used to stabilize and clamp the edges of the square silicon core and prevent rotational displacement. The side wall of the positioning block 58 has a limiting groove, in which a fixing block 582 is slidably arranged. The inner side of the fixing block 582 is also a "V"-shaped structure, which cooperates with the positioning groove 581 to form a double-point clamping. The two sets of fixing blocks 582 are driven by symmetrically arranged electric push rods 584. The piston end of the push rod is connected to the fixing block 582, pushing it to move towards the center to press the silicon core.

[0037] Crucially, the inner wall of the fixing block 582 is embedded with a pressure sensor 583, which can detect the axial pressure applied to the end face of the silicon core in real time and feed the signal back to the PLC control system to form a closed-loop pressure regulation. The operator can set the target pressure value, and the system will automatically adjust the output force of the electric push rod 584 to ensure that the pressure is stable and uniform during the welding process, and avoid silicon core breakage due to overpressure or poor fusion due to insufficient pressure.

[0038] A heating mechanism is provided between the two sets of positioning clamps 5, including a pair of side rails 6 vertically installed on the inner wall of the sealing shell 1. A heating plate 62 is slidably arranged between the two side rails 6, and two sets of symmetrically arranged welding rings 63 are embedded inside the heating plate 63. A ring induction coil is provided inside the welding ring 63. When energized, it generates an alternating magnetic field to perform high-frequency induction heating on the docking area of ​​the silicon core, causing it to melt locally and form a molten pool.

[0039] One of the side rails 6 has a lead screw 61 rotatably mounted inside. The lead screw 61 is threaded to one side of the heating plate 62 and is driven by a motor. It can drive the heating plate 62 to slide up and down in the vertical direction, so that the heating area can be scanned and moved to realize zone melting welding. This effectively promotes uniform solidification of the molten zone, reduces thermal stress and bubble residue, and improves the welding quality.

[0040] The upper end of the sealing shell 1 is provided with an installation cavity, which houses a vacuum pump 8. The pump's extraction port extends into the interior of the sealing shell 1 through a metal pipe. The vacuum pump 8 is used to extract the air from the sealing shell 1 before welding, establishing an initial vacuum environment and creating conditions for subsequent inert gas replacement.

[0041] The atmosphere protection mechanism is used to provide and maintain a high-purity argon atmosphere. It includes an argon cylinder 9 located outside the sealed shell. Its outlet is connected to a pressure reducing valve 10 through a stainless steel pipe to reduce the high-pressure gas to the working pressure of the equipment. After pressure reduction, the gas enters the gas purification mechanism 11.

[0042] The gas purification mechanism 11 includes a housing 111 with an air inlet and an air outlet at both ends. Inside, along the airflow direction, there are sequentially arranged an oxygen absorption layer 112, a molecular sieve adsorption layer 113, and a particle filter layer 114, which can effectively remove residual oxygen, moisture, and particulate impurities from argon gas, ensuring that the purity of the gas entering the cavity reaches the semiconductor grade standard.

[0043] The oxygen absorption layer 112 includes a heated oxygen absorber filling layer, the oxygen absorber being a palladium catalyst, filled between stainless steel mesh partitions; a molecular sieve adsorption layer 113, using 4A or 13X type zeolite molecular sieves, encapsulated in a porous stainless steel tube, with stainless steel sintered felt filter screens at both ends of the porous stainless steel tube to prevent molecular sieve powder from escaping; and a particulate filter layer 114, a high-efficiency particulate air filter, using a polytetrafluoroethylene (PTFE) membrane filter element or a stainless steel sintered porous filter sheet, installed at the end of the outer shell 111 near the air outlet.

[0044] The purified argon gas is introduced into the sealed shell 1 through the gas supply pipe 13. The pipe is equipped with a precision flow controller 12 and a pneumatic valve, which can accurately control the gas filling rate and maintain the flow rate. After the gas enters the sealed shell 1, it is guided by the gas guide plate 7 set at the top and uniformly covers the welding area in a laminar flow form to avoid oxidation caused by local eddies.

[0045] To ensure the safe operation of the equipment and the safety of the operators, this device is also equipped with a number of safety protection measures: the explosion-proof observation window is located in the center of the sealed door 2, and adopts a composite structure of high temperature resistant quartz glass and metal frame, which has explosion-proof and heat insulation functions, allowing operators to observe the welding process without opening the cavity.

[0046] The emergency stop button is located in a prominent position on the front of the device. Pressing it will immediately cut off the main power supply and stop all movement and heating actions.

[0047] The heating system has an independent thermocouple or bimetallic temperature control switch inside the heating plate 62 for overheat protection. When the temperature rises abnormally and exceeds the set threshold, the high-frequency power supply is automatically cut off.

[0048] The gas pipeline pressure safety valve is installed on the argon gas inlet pipeline. When the pipeline pressure exceeds the set value, it automatically releases pressure to prevent the risk of overpressure due to the failure of the pressure reducing valve 10.

[0049] During welding, open the sealing door 2 and place the two square silicon cores to be welded into the "V"-shaped positioning grooves 581 of the positioning fixtures 5 on the left and right sides respectively. Close the sealing door 2, start the vacuum pump 8, and evacuate the inside of the sealing shell 1 to the set vacuum level to expel most of the air. Open the pneumatic valve, and high-purity argon gas, after being depressurized and purified, is slowly filled into the cavity by the flow rate controlled by the precision flow controller 12. Repeat the "vacuuming-argon filling" process multiple times to completely replace the impurity gas in the cavity and establish a high-purity inert atmosphere. Adjust the distance between the two sliding blocks 51 by the bidirectional lead screw 41 to achieve coarse positioning. Then, drive the adjusting rail 2 54 and adjusting rail 3 step by step by the lead screw 1 53, lead screw 2 55, and lead screw 3 57. 56 and positioning block 58 enable three-dimensional fine adjustment in X / Y / Z directions to align the end faces of the two silicon cores. The electric push rod 584 is activated to push the fixing block 582 to press the end face of the silicon core. The pressure sensor 583 provides real-time feedback of the pressure value. The PLC system adjusts the closed-loop to the set pressure, and the high-frequency power supply is activated. The ring induction coil is energized and heated to raise the temperature of the docking area above the melting point of silicon to form a molten pool. At the same time, the lead screw 61 drives the heating plate 62 to move slowly up and down to achieve zone melting scanning heating, ensuring uniform fusion of the welding area. After heating is stopped, argon gas is kept flowing for cooling. After the welding area is completely solidified, the pressure is gradually released, the pneumatic valve is closed, the sealing door 2 is opened, and the fused silicon core is taken out.

[0050] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A zone melting method for welding square silicon cores, characterized in that: The system includes a sealing shell (1), a sealing door (2) on one side of the sealing shell (1), the sealing door (2) sliding in a slide (3) on the sealing shell (1), a pair of positioning clamps (5) for fixing and aligning two square silicon cores, a heating mechanism for heating the silicon core docking area, and an atmosphere protection mechanism. The pair of positioning clamps (5) slide relative to each other in an adjustment track (4) inside the sealing shell (1), the heating mechanism is located between the pair of positioning clamps (5), and the atmosphere protection mechanism is connected to the sealing shell (1), together forming a closed working environment.

2. The zone melting method square silicon core welding device according to claim 1, characterized in that: The positioning fixture (5) includes a sliding block (51) that slides within the adjusting rail (4). An adjusting rail one (52) is fixedly provided on one side of the sliding block (51). An adjusting rail two (54) is slidably provided within the adjusting rail one (52). An adjusting rail three (56) is slidably provided within the adjusting rail two (54). A positioning block (58) is slidably provided within the adjusting rail three (56). Two sets of positioning grooves (581) are provided within the positioning block (58). A fixing block (582) is slidably provided within the limiting groove provided on the side wall of the positioning block (58).

3. The zone melting method square silicon core welding device according to claim 2, characterized in that: The positioning block (58) has a symmetrical electric push rod (584) on one side. The piston end of the electric push rod (584) is connected to one side of the fixed block (582). The inner side of the fixed block (582) is provided with a "V" shaped groove. The inner wall of the fixed block (582) is embedded with a pressure sensor (583).

4. The zone melting method square silicon core welding device according to claim 3, characterized in that: A lead screw 1 (53) is rotatably installed inside the first adjustment rail (52). The lead screw 1 (53) is threaded to the bottom of the second adjustment rail (54). A lead screw 2 (55) is rotatably installed inside the second adjustment rail (54). The lead screw 2 (55) is threaded to one side of the third adjustment rail (56). A lead screw 3 (57) is rotatably installed inside the third adjustment rail (56). The lead screw 3 (57) is threaded to the positioning block (58). The lead screw 1 (53), lead screw 2 (55), and lead screw 3 (57) are driven by their respective motors.

5. The zone melting method square silicon core welding device according to claim 4, characterized in that: A bidirectional lead screw (41) is rotatably installed inside the adjustment track (4). The two ends of the bidirectional lead screw (41) are threadedly connected to two sets of sliding blocks (51) respectively, and one end of the bidirectional lead screw (41) is connected to the output shaft of the motor.

6. The zone melting method square silicon core welding device according to claim 1, characterized in that: The heating mechanism includes a pair of side rails (6) respectively disposed on the inner wall of the sealing shell (1), a heating plate (62) is slidably disposed between the two sets of side rails (6), and two sets of welding rings (63) are disposed inside the heating plate (62).

7. The zone melting method square silicon core welding device according to claim 6, characterized in that: One of the side rails (6) is rotatably equipped with a lead screw (61), which is threadedly connected to one side of the heating plate (62) and is driven by a motor.

8. The zone melting method square silicon core welding device according to claim 1, characterized in that: The upper end of the sealing shell (1) has a cavity, and a vacuum pump (8) is installed in the cavity. The vacuum pump (8) has a pipe connected to its exhaust port, which extends into the interior of the sealing shell (1).

9. The zone melting method square silicon core welding device according to claim 1, characterized in that: The atmosphere protection mechanism includes an argon cylinder (9) disposed on one side of the sealed shell (1). The outlet of the argon cylinder (9) is connected to the gas purification mechanism (11) through a pipe. A pressure reducing valve (10) is disposed on the pipe. A gas supply pipe (13) is connected to the outlet of the gas purification mechanism (11). The gas supply pipe (13) extends into the interior of the sealed shell (1). A precision flow controller (12) and a pneumatic valve are disposed on the gas supply pipe (13). A gas guide plate (7) is disposed on the top of the sealed shell (1).

10. The zone melting method square silicon core welding device according to claim 9, characterized in that: The gas purification mechanism (11) includes a shell (111), with an air inlet and an air outlet at both ends of the shell (111). Inside the shell (111), an oxygen absorption layer (112), a molecular sieve adsorption layer (113), and a particle filter layer (114) are arranged in sequence.

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