A ceramic disc and ceramic shaft body welding jig and welding method

Abstract

The application discloses a ceramic disc and ceramic shaft body welding jig and a welding method, and belongs to the technical field of ceramic welding. The jig comprises a bottom plate, a plurality of positioning rods are arranged on the bottom plate, ceramic shaft positioning pieces are arranged on the positioning rods, the bottom of each ceramic shaft positioning piece is provided with a circular positioning groove matched with a ceramic disc, an axle through hole for allowing a ceramic shaft body to pass through is arranged on each ceramic shaft positioning piece, the center line of the axle through hole coincides with the center line of the circular positioning groove, the upper surface of each ceramic shaft positioning piece is provided with a plurality of clamping grooves, a positioning strip matched with each clamping groove is arranged in any clamping groove, the inner side wall of each positioning strip is matched with the outer side wall of the ceramic shaft body, the bottom of the ceramic shaft body is welded with the ceramic disc, a top positioning piece is arranged above the top of the ceramic shaft body, and the top positioning piece is arranged on the positioning rod. When the ceramic disc and the ceramic shaft body are welded, the welding jig is used, the concentricity of the ceramic shaft body and the ceramic disc is improved, and the process consistency is ensured.

Description

Technical Field

[0001] This invention relates to the field of ceramic welding technology, and in particular to a welding fixture and welding method for ceramic discs and ceramic shafts. Background Technology

[0002] In semiconductor wafer fabrication processes, aluminum nitride ceramic heaters are core components for achieving precise temperature control. The concentricity of the welded assembly between the metal shaft and the aluminum nitride ceramic base plate is a key indicator affecting product performance and availability for shipment. In the existing production and quality inspection system, the concentricity of the shaft and ceramic base plate is a mandatory acceptance criterion for product shipment. Many products that meet performance standards fail to pass acceptance due to excessive concentricity, resulting in a significant waste of raw materials, labor, and equipment resources, and driving up production costs.

[0003] The existing welding process between the shaft and ceramic base plate of aluminum nitride ceramic heaters has the following problems:

[0004] The positioning method is cumbersome and inefficient. Operators need to use a steel ruler to measure the distance from the shaft to the edge of the ceramic base plate multiple times, usually comparing four or more points repeatedly to ensure the coaxiality of the shaft and the ceramic base plate. After each adjustment of the shaft position, all calibrated points must be remeasured, making the operation process lengthy and severely restricting the production cycle.

[0005] It can easily cause damage to the solder layer: During the process of adjusting the position of the shaft to correct the concentricity deviation, the shaft and the solder layer pre-coated on the welding surface of the ceramic base plate slide relative to each other, which can easily scratch and wear the solder layer, resulting in uneven solder distribution, which directly affects the welding quality and interface bonding strength.

[0006] Positioning accuracy is difficult to control: The shaft is a cylindrical structure, and adjusting its position in one direction will cause positional shifts in other directions, leading to the failure of the concentricity of the calibrated points and forming a cycle of "adjustment-shift-readjustment". At the same time, the small internal space of the welding equipment makes it difficult for operators to achieve horizontal readings. In addition, the steel ruler itself has limited precision, resulting in concentricity control accuracy far below the process requirements (usually required to be less than or equal to 0.05 mm), and frequent concentricity deviations in products. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a welding fixture and welding method for ceramic discs and ceramic shafts, which can improve the concentricity of the welding process and increase the product qualification rate and production efficiency.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0009] This invention discloses a welding fixture for a ceramic disc and a ceramic shaft. The fixture includes a base plate with several positioning rods. A ceramic shaft positioning component is fitted onto each positioning rod. The bottom of the ceramic shaft positioning component has a circular positioning groove that mates with the ceramic disc. The ceramic shaft positioning component has a shaft through hole for the ceramic shaft to pass through, with the center line of the shaft through hole coinciding with the center line of the circular positioning groove. The upper surface of the ceramic shaft positioning component has several slots, and each slot has a positioning strip that mates with the slot. The inner sidewall of the positioning strip mates with the outer sidewall of the ceramic shaft. The bottom of the ceramic shaft is welded to the ceramic disc. A top positioning component is provided above the top of the ceramic shaft and is fitted onto the positioning rod.

[0010] Preferably, the number of card slots is three, and the three card slots are evenly arranged along the circumferential direction.

[0011] Preferably, the top of the positioning rod is provided with an external thread section, and a nut is fitted on the external thread section, with the thread located above the top positioning member.

[0012] Preferably, the positioning rod is made of graphite, and the ceramic shaft positioning component, the top positioning component, and the positioning strip are all aluminum nitride ceramic or alumina ceramic.

[0013] Preferably, the bottom of the top positioning member is provided with a first positioning groove that cooperates with the counterweight, and the bottom of the counterweight is provided with a second positioning groove that cooperates with the top of the ceramic shaft.

[0014] Another aspect of the present invention discloses a method for welding a ceramic disc and a ceramic shaft using the aforementioned welding fixture, the method comprising the following steps:

[0015] S1: Fixture and workpiece pretreatment

[0016] The welding fixture is ultrasonically cleaned and argon plasma cleaned. After cleaning the welding surface of the ceramic disk, solder is evenly applied to form a solder layer. The disk is then dried in an oven before use.

[0017] S2: Bottom centering assembly

[0018] Place the ceramic disc on the base plate with the solder layer side facing up, then install the ceramic shaft positioning component on the positioning rod, so that the circular positioning groove matches the circular ceramic disc, which limits the relative position of the ceramic disc and the ceramic shaft positioning component. Insert the three positioning strips into the slots respectively. After installation, all three positioning strips are in contact with the outer wall of the ceramic shaft body, completing the radial concentric positioning of the ceramic shaft body and the ceramic disc.

[0019] S3: Top limit assembly

[0020] First, place the counterweight on the top of the ceramic shaft so that the top of the ceramic shaft engages with the second positioning groove. Then, install the top positioning component on the positioning rod and move the top positioning component downward so that the first positioning groove engages with the counterweight, thereby achieving axial limiting and radial secondary locking of the ceramic shaft.

[0021] S4: Rigid Locking

[0022] A graphite washer is placed on the external thread section, and a graphite nut is tightened from top to bottom above the top positioning part, with the torque controlled at 4 to 6 N•m, so that the top positioning part, ceramic shaft, ceramic disk, and base plate are locked together to form a rigid whole.

[0023] S5: Batch Welding

[0024] Multiple sets of ceramic shafts and ceramic disk assembly components that have been positioned and locked are placed in batches into a vacuum welding furnace and welded according to the preset aluminum nitride ceramic heater welding process parameters.

[0025] S6: Fixture Disassembly and Reuse

[0026] After welding is completed, wait for the components to cool to room temperature with the furnace, remove the graphite bolts, and then remove the top positioning component, counterweight and positioning strip in sequence to complete the jig disassembly. After cleaning, the disassembled jig can be reused for welding positioning of the next batch of products.

[0027] The above technical solution has the following beneficial effects:

[0028] By using the welding fixture of this application when welding ceramic discs and ceramic shafts, the concentricity of the welding between the ceramic shaft and the ceramic disc can be improved, thus ensuring product quality.

[0029] By using welding fixtures, the positioning of ceramic shafts can be completed quickly, which can effectively protect the solder layer and avoid problems such as excessive sliding during the adjustment of ceramic shafts, which would cause the solder layer to scratch, wear and uneven distribution.

[0030] By using welding fixtures to ensure the relative position of the ceramic shaft and ceramic disc, and then performing batch welding in a vacuum welding furnace, process consistency and product yield can be guaranteed. Attached Figure Description

[0031] Figure 1 This is a cross-sectional structural diagram of a welding fixture for ceramic disc and ceramic shaft according to the present invention.

[0032] Figure 2 This is a cross-sectional exploded view of the welding fixture for ceramic disc and ceramic shaft according to the present invention.

[0033] Figure 3 This is a schematic diagram of the installation structure of the positioning strip and the ceramic shaft of the present invention;

[0034] Figure 4 This is a schematic diagram of the ceramic shaft positioning component of the present invention;

[0035] Figure 5 This is a schematic diagram of the connection between the ceramic shaft and the ceramic disk of the present invention. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] refer to Figures 1-5 A welding fixture for ceramic discs and ceramic shafts is provided. The fixture includes a base plate 1, on which a plurality of positioning rods 4 are provided. A ceramic shaft positioning component 5 is sleeved on the positioning rods 4. The bottom of the ceramic shaft positioning component 5 is provided with a circular positioning groove 3 that mates with the ceramic disc 2. The ceramic shaft positioning component 5 is provided with a shaft through hole 7 for the ceramic shaft 6 to pass through. The center line of the shaft through hole 7 coincides with the center line of the circular positioning groove 3. The upper surface of the ceramic shaft positioning component 5 is provided with a plurality of slots 10. A positioning strip 11 that mates with the slot 10 is provided in any slot 10. The inner side wall of the positioning strip 11 mates with the outer side wall of the ceramic shaft 6. The bottom of the ceramic shaft 6 is welded to the ceramic disc 2. A top positioning component 8 is provided above the top of the ceramic shaft 6 and is sleeved on the positioning rods 4.

[0038] Specifically, the base plate 1 serves as a support and can be an alumina ceramic plate or an aluminum nitride ceramic plate to meet the needs of vacuum welding. The base plate 1 can be a disc-shaped plate, and several positioning rods 4 are provided on the base plate 1. The number of positioning rods 4 can be three, and the three positioning rods 4 are evenly arranged on the edge of the base plate 1 in a circumferential direction. Alternatively, there can be six, and the six positioning rods 4 are arranged in three groups of two, evenly arranged on the edge of the base plate 1 in a circumferential direction. The ceramic shaft positioning component 5 is provided with three slots 10. After the ceramic shaft positioning component 5 is installed, the two positioning rods 4 of one group of positioning rods are set on both sides of the slot 10, symmetrically arranged about the slot 10.

[0039] The bottom of the ceramic shaft positioning component 5 is provided with a circular positioning groove 3 that mates with the ceramic disc 2. The ceramic disc 2 has a disc-shaped structure. Before welding, the ceramic disc 2 is embedded into the circular positioning groove 3 to complete the installation, and then the ceramic shaft body 6 is positioned in the next step. The ceramic shaft positioning component 5 can also be a disc-shaped structure. The central axis of the circular positioning groove 3 coincides with the central axis of the disc-shaped ceramic shaft positioning component 5. The ceramic shaft positioning component 5 is provided with a through hole that mates with the positioning rod 4 so that the ceramic shaft positioning component 5 is sleeved on the positioning rod. During installation, the ceramic disc 2 is placed approximately at the center of the base plate 1, and then the ceramic shaft positioning component 5 is installed. It is moved down until the circular positioning groove 3 mates with the ceramic disc 2, limiting the relative position of the ceramic disc 2 and the ceramic shaft positioning component 5. The ceramic shaft positioning component 5 is a circular plate-shaped structure of aluminum nitride ceramic or alumina ceramic that is resistant to high temperature and has low thermal deformation, and is adapted to the outer dimensions of the base plate 1.

[0040] The ceramic shaft positioning component 5 is provided with a shaft through hole 7 for the ceramic shaft body 6 to pass through. The center line of the shaft through hole 7 coincides with the center line of the circular positioning groove 3. The circular positioning groove 3 faces downward and mates with the ceramic disk 2. To weld the ceramic shaft body 6 and the ceramic disk 2, the shaft through hole 7 needs to be provided so that the ceramic shaft body 6 can contact the ceramic disk 2 through the ceramic shaft positioning component 5. The diameter of the shaft through hole 7 can be larger than the ceramic shaft body 6 that passes through. The center line of the shaft through hole 7 coincides with the center line of the circular positioning groove 3 to ensure the concentricity of the ceramic shaft body 6 and the ceramic disk 2.

[0041] The upper surface of the ceramic shaft positioning component 5 is provided with several slots 10. Each slot 10 is provided with a positioning strip 11 that mates with the slot 10. The slots 10 are evenly arranged around the central axis of the shaft through hole 7 in the circumferential direction. During installation, after the ceramic shaft 6 passes through the shaft through hole 7, it stops before contacting the solder layer. The positioning strips 11 are then inserted into the slots in sequence to adjust the ceramic shaft 6 to the required center position. After adjustment, the ceramic shaft 6 is pressed down so that the bottom welding area contacts the solder layer to complete the positioning.

[0042] The inner wall of the positioning strip 11 mates with the outer wall of the ceramic shaft 6. After the positioning strip 11 is installed, the position of the ceramic shaft 6 is adjusted radially so that it is centered and concentric with the ceramic disc 2 to ensure the product quality requirements after welding. Specifically, after the positioning strip 11 is installed, one end facing the ceramic shaft 6 contacts and mates with the ceramic shaft 6. The end of the positioning strip 11 can be an arc-shaped curved surface that mates with the ceramic shaft 6. In other embodiments of this example, the same number of protrusions can be set on the outer wall of the ceramic shaft 6 according to the number of positioning strips 11. In this case, the end of the positioning strip 11 facing the ceramic shaft 6 after installation can be set as a plane that mates with the protrusions to reduce the difficulty of manufacturing and assembly.

[0043] The positioning strip 11 is made of the same material as the ceramic shaft positioning part 5, or it can be aluminum nitride ceramic or alumina ceramic. Its size is fully compatible with the slot 10 of the bottom positioning plate, and it can be embedded and installed without any loose gaps. After the three positioning strips 11 are embedded in the slot 10, their inner sides form a circular centering area that is compatible with the bottom of the ceramic shaft 6, realizing three-point radial positioning of the bottom of the ceramic shaft 6, ensuring that the ceramic shaft 6 coincides with the central axis of the ceramic disk 2, and there is no need to frequently move the ceramic shaft 6 during the positioning process, thus avoiding solder scratch damage from the root.

[0044] The bottom of the ceramic shaft 6 is welded to the ceramic disk 2. Specifically, both the bottom of the ceramic shaft 6 and the ceramic disk 2 can be made of aluminum nitride ceramic material, and the two are welded together to form an aluminum nitride ceramic heater.

[0045] A top positioning component 8 is provided above the top of the ceramic shaft 6. The top positioning component 8 is sleeved on the positioning rod 4. The top positioning component 8 positions the ceramic shaft 6 from the top and further restricts its position relative to the ceramic disk 2. The top positioning component 8 is specifically a circular plate structure, made of the same high-temperature resistant ceramic material as the ceramic shaft positioning component 5, and is sleeved on the positioning rod 4 through the hole provided on it.

[0046] In some embodiments, the number of slots 10 is three, and the three slots 10 are evenly arranged along the circumferential direction to cooperate with the positioning strip 11 to position the ceramic shaft 6 in the radial direction.

[0047] In some embodiments, the top of the positioning rod 4 is provided with an external thread section 12, and a nut 13 is fitted on the external thread section 12, with the thread 13 located above the top positioning member 8.

[0048] Specifically, nut 13 is made of graphite material and is used in conjunction with graphite gaskets. It has the characteristics of high temperature resistance greater than or equal to 1700℃, low coefficient of thermal expansion, and non-reaction with solder. Top positioning part 8 presses the ceramic shaft 6 and ceramic disk 2 from the axial direction. Nut 13 is tightened from top to bottom. With the help of graphite gaskets, the three are rigidly fastened to form a closed positioning frame, which completely locks the relative position of ceramic shaft 6 and ceramic disk 2, and prevents any relative displacement during the welding process.

[0049] In some embodiments, the positioning rod 4 is made of graphite, and the ceramic shaft positioning component 5, the top positioning component 8, and the positioning strip 11 are all aluminum nitride ceramic or alumina ceramic to meet the application conditions of high-temperature vacuum welding.

[0050] In some embodiments, the bottom of the top positioning member 8 is provided with a first positioning groove 9 that cooperates with the counterweight 15, and the bottom of the counterweight 15 is provided with a second positioning groove 14 that cooperates with the top of the ceramic shaft 6. The inner diameter and depth of the first positioning groove 9 are precisely matched with the shape of the counterweight 15, and the top of the ceramic shaft 6 cooperates with the second positioning groove 14, which can realize the axial limiting and radial secondary locking of the ceramic shaft 6. Combined with the centering effect of the bottom positioning strip 11, a dual positioning system is formed. During installation, the counterweight 15 is first placed on the top of the ceramic shaft 6, and then the top positioning member 8 is installed. The nut 13 is tightened and pressed on the upper side wall of the top positioning member 8. In other embodiments of this embodiment, the second positioning groove 14 that cooperates with the counterweight 15 can be provided on the top of the counterweight 15.

[0051] The counterweight 15 can be a tungsten steel counterweight, which is a high-density disc-shaped structure and is embedded in the top positioning component 8. Utilizing the high density characteristics of tungsten steel, it applies axial preload through its own weight to further stabilize the positioning posture of the shaft, suppress the slight axial movement caused by thermal stress during the welding heating process, and ensure that the positioning state does not fail during the welding process.

[0052] A method for welding a ceramic disc and a ceramic shaft using a welding fixture, the method comprising the following steps:

[0053] S1: Fixture and workpiece pretreatment

[0054] The welding fixture is ultrasonically cleaned and argon plasma cleaned to remove surface oil, dust and oxide layer. After cleaning the welding surface of ceramic disk 2, solder is evenly applied to form a solder layer. After coating, the welding surface is prevented from being scratched. It is then dried in an oven before use.

[0055] S2: Bottom centering assembly

[0056] Place the ceramic disc 2 on the base plate 1 with the solder layer side facing upwards. Then install the ceramic shaft positioning piece 5 on the positioning rod 4, allowing the circular positioning groove 3 to mate with the circular ceramic disc 2, thus defining the relative position of the ceramic disc 2 and the ceramic shaft positioning piece 5. Insert the three positioning strips 11 into the slots 10 respectively. After installation, all three positioning strips 11 are in contact with the outer wall of the ceramic shaft 6, completing the radial concentric positioning of the ceramic shaft 6 and the ceramic disc 2. Specifically, when installing the ceramic shaft 6, you can stop the axial movement when its bottom is about to contact the solder layer, for example, when it is 3-5mm away. After stopping, insert the three positioning strips 11 into the slots 10 respectively, and push the ceramic shaft 6 downwards so that its bottom contacts the solder layer, completing the centering assembly. Alternatively, you can first install two positioning strips 11, then slowly move it downwards until it contacts the solder layer, and then install the last positioning strip 11 to complete the centering assembly. During the positioning process, there is no need to move the ceramic shaft 6 multiple times to avoid damage to the solder layer.

[0057] S3: Top limit assembly

[0058] First, the counterweight 15 is placed on the top of the ceramic shaft 6, so that the top of the ceramic shaft 6 mates with the second positioning groove 14. Then, the top positioning part 8 is installed on the positioning rod 4. The top positioning part 8 is moved down so that the first positioning groove 9 mates with the counterweight 15, thereby achieving axial limiting and radial secondary locking of the ceramic shaft 6. Specifically, the counterweight 15 is first installed on the top of the ceramic shaft 6, and then the top positioning part 8 is placed on the positioning rod 4 so that the first positioning groove 9 mates with the counterweight 15. The counterweight 15 is made of tungsten steel and applies axial preload through its own weight to stabilize the positioning posture of the ceramic shaft 6.

[0059] S4: Rigid Locking

[0060] A graphite washer is fitted onto the external thread section 12, and the graphite nut 13 is tightened from top to bottom above the top positioning member 8, with the torque controlled at 4 to 6 N•m, so that the top positioning member 8, ceramic shaft 6, ceramic disk 2, and base plate 1 are locked together to form a rigid whole. Specifically, after the graphite washer is fitted, it is located on the upper surface of the top positioning member 8. The graphite nut 13 is tightened from top to bottom above the graphite washer, so that the top positioning member 8, ceramic shaft 6, ceramic disk 2, and base plate 1 are locked together to form a rigid whole. An automated torque wrench can be used to tighten it, with the torque controlled at 4 N•m or 6 N•m.

[0061] S5: Batch Welding

[0062] The assembled components of multiple ceramic shafts 6 and ceramic discs 2, which have been positioned and locked, are placed in batches into a vacuum welding furnace and welded according to the preset aluminum nitride ceramic heater welding process parameters. During the welding process, the rigid frame and dual positioning structure of the fixture can effectively offset the deformation and displacement caused by thermal stress, ensuring stable concentricity.

[0063] S6: Fixture Disassembly and Reuse

[0064] After welding is completed, wait for the components to cool to room temperature with the furnace, remove the graphite bolts, and then remove the top positioning component 8, counterweight 15 and positioning strip 11 in sequence to complete the jig disassembly. After cleaning, the disassembled jig can be reused for welding positioning of the next batch of products. The service life of a single jig is not less than 500 times, which is suitable for mass production cost control requirements.

[0065] This invention solves the technical pain points of low concentricity control accuracy, easy damage to solder, low production efficiency and poor process consistency in the welding process of ceramic shaft 6 and ceramic disk 2 of existing aluminum nitride ceramic heaters through the synergistic design of special welding fixtures and matching welding processes. It is adapted to the needs of mass production scenarios and achieves significant improvements in accuracy, efficiency, cost and reliability.

[0066] This invention replaces manual steel ruler measurement and calibration with a dual rigid positioning structure consisting of multi-point centering at the bottom and a groove limiting at the top. This eliminates concentricity deviations caused by space constraints, insufficient measuring tool accuracy, and human error. It can stably control the welding concentricity of the ceramic shaft 6 and the ceramic disk 2 to a level of less than or equal to 0.03mm, fully meeting the mandatory requirements for product delivery. At the same time, it completely avoids the concentricity offset problem caused during shaft adjustment, reducing the product scrap rate caused by concentricity deviation to below 1%, significantly reducing the waste of raw materials, labor, and equipment resources, and lowering production costs.

[0067] The welding fixture of the present invention can achieve rapid and accurate positioning of the ceramic shaft 6 without repeatedly moving the ceramic shaft 6 to adjust its position. This fundamentally avoids the relative sliding between the ceramic shaft 6 and the pre-coated solder layer, eliminates the problems of solder layer scratching, wear and uneven distribution, ensures that the solder at the welding interface is full and tightly bonded, significantly improves the welding strength and interface stability, extends the service life of the aluminum nitride ceramic heater, and reduces the risk of failure during subsequent use of the product.

[0068] Significantly improving production efficiency and adapting to the needs of large-scale mass production, this invention eliminates the cumbersome manual process of multi-point measurement, adjustment, and re-measurement. The positioning fixture enables rapid assembly and rigid locking, reducing the positioning time of a single product by more than 80%. At the same time, the fixture can be reused with a single-use lifespan of more than 500 times, is easy to disassemble, and, combined with batch welding processes, can increase the production cycle by more than 50%, completely solving the bottleneck of low efficiency of manual calibration that restricts mass production, and meeting the needs of standardized and large-scale production.

[0069] By improving process consistency and stabilizing product yield, this invention replaces manual calibration methods that rely on operator experience with standardized welding fixture structures and fixed process steps. This eliminates calibration differences between different batches and between different operators, significantly improving product concentricity consistency. The concentricity yield in mass production is stabilized at over 95%, effectively avoiding yield fluctuations, improving product quality stability, and enhancing product market competitiveness.

[0070] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A welding fixture for a ceramic disc and a ceramic shaft, characterized in that, The fixture includes a base plate with several positioning rods. A ceramic shaft positioning component is fitted onto each positioning rod. The bottom of the ceramic shaft positioning component has a circular positioning groove that mates with a ceramic disc. The ceramic shaft positioning component has a shaft through hole for the ceramic shaft to pass through. The center line of the shaft through hole coincides with the center line of the circular positioning groove. The upper surface of the ceramic shaft positioning component has several slots. A positioning strip mates with the slot in any of the slots. The inner sidewall of the positioning strip mates with the outer sidewall of the ceramic shaft. The bottom of the ceramic shaft is welded to the ceramic disc. A top positioning component is provided above the top of the ceramic shaft and is fitted onto the positioning rod.

2. The ceramic disc and ceramic shaft welding fixture according to claim 1, characterized in that, The number of card slots is three, and the three card slots are evenly arranged along the circumference.

3. The ceramic disc and ceramic shaft welding fixture according to claim 1, characterized in that, The top of the positioning rod is provided with an external thread section, and a nut is fitted on the external thread section. The thread is located above the top positioning member.

4. The ceramic disc and ceramic shaft welding fixture according to claim 1, characterized in that, The positioning rod is made of graphite, and the ceramic shaft positioning component, the top positioning component, and the positioning strip are all made of aluminum nitride ceramic or alumina ceramic.

5. The ceramic disc and ceramic shaft welding fixture according to claim 1, characterized in that, The bottom of the top positioning component is provided with a first positioning groove that mates with the counterweight, and the bottom of the counterweight is provided with a second positioning groove that mates with the top of the ceramic shaft.

6. A method for welding a ceramic disc and a ceramic shaft using a welding fixture as described in any one of claims 1-5, characterized in that, The method includes the following steps: S1: Fixture and workpiece pretreatment The welding fixture is ultrasonically cleaned and argon plasma cleaned. After cleaning the welding surface of the ceramic disk, solder is evenly applied to form a solder layer. The disk is then dried in an oven before use. S2: Bottom centering assembly Place the ceramic disc on the base plate with the solder layer side facing up, then install the ceramic shaft positioning component on the positioning rod, so that the circular positioning groove matches the circular ceramic disc, which limits the relative position of the ceramic disc and the ceramic shaft positioning component. Insert the three positioning strips into the slots respectively. After installation, all three positioning strips are in contact with the outer wall of the ceramic shaft body, completing the radial concentric positioning of the ceramic shaft body and the ceramic disc. S3: Top limit assembly First, place the counterweight on the top of the ceramic shaft so that the top of the ceramic shaft engages with the second positioning groove. Then, install the top positioning component on the positioning rod and move the top positioning component downward so that the first positioning groove engages with the counterweight, thereby achieving axial limiting and radial secondary locking of the ceramic shaft. S4: Rigid Locking A graphite washer is placed on the external thread section, and a graphite nut is tightened from top to bottom above the top positioning part, with the torque controlled at 4 to 6 N•m, so that the top positioning part, ceramic shaft, ceramic disk, and base plate are locked together to form a rigid whole. S5: Batch Welding Multiple sets of ceramic shafts and ceramic disk assembly components that have been positioned and locked are placed in batches into a vacuum welding furnace and welded according to the preset aluminum nitride ceramic heater welding process parameters. S6: Fixture Disassembly and Reuse After welding is completed, wait for the components to cool to room temperature with the furnace, remove the graphite bolts, and then remove the top positioning component, counterweight and positioning strip in sequence to complete the jig disassembly. After cleaning, the disassembled jig can be reused for welding positioning of the next batch of products.

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