Wafer manufacturing machine rack welding forming process and jig

Abstract

The present application relates to wafer manufacturing equipment processing technical field, disclose a wafer manufacturing machine frame welding forming process and jig, its process includes: to the frame closed hole site prefilling ceramic stud;The structure is placed in the jig base preadjusting flatness, the initial clamping force is applied through proportional servo hydraulic cylinder;When the underframe is welded, cooling water is forced to dissipate heat, and the top frame is preheated using a heating belt;Real-time monitoring of high-precision parts thermal deformation displacement, when reaching the threshold, the piezoelectric ceramic actuator applies a reverse thrust to compensate;When cooling after welding, the command hydraulic cylinder executes a stepwise pressure relief creep release program.The jig includes flexible yielding clamping, differential heat flow guide control and dynamic fine adjustment compensation systems, etc..The present application effectively suppresses welding thermal deformation, relaxes residual stress, and improves the final forming precision of the frame through differential heat field control, dynamic thrust intervention and stepwise creep pressure relief.

Description

Technical Field

[0001] This invention relates to the field of wafer manufacturing equipment processing technology, and in particular to the frame welding and forming process and fixtures for wafer manufacturing machines. Background Technology

[0002] To meet the high-precision processing requirements of wafer fabrication machines, various components are typically installed within the machine rack during assembly. This ensures that the processing parts and related components meet the requirements for high positioning accuracy and flatness. Therefore, during the welding and forming of the wafer fabrication machine rack, the parallelism and flatness tolerances of each structure on the rack must be strictly controlled within 0.2 millimeters.

[0003] However, in actual welding operations, due to the complex structure of the frame and the varying rigidity of different parts, it is difficult to accurately position and fix multiple welding points and complex spatial structures in one go. Currently, rigid fixtures are usually used to forcibly clamp the frame structural components. This clamping method cannot provide room for retreat when the metal expands due to heat, which can easily cause compressive stress inside the structure. During the fixture disassembly stage after welding, the sudden release of the clamping mechanism will cause the accumulated elastic strain energy inside to be released suddenly, resulting in elastic rebound of the frame, making it difficult to control the final forming dimensions, often exceeding the tolerance requirement of 0.2 mm.

[0004] Furthermore, due to differences in structural thickness and load-bearing capacity among different parts of the frame (such as the base frame and top frame), the heat distribution and heat transfer rate vary across different areas under the influence of welding heat sources, making them prone to uneven deformation under thermal stress. Existing welding processes lack targeted heat transfer intervention methods for different areas when dealing with such complex rigid structures, and when facing high-precision mounting surfaces, they lack proactive monitoring and physical intervention for localized thermal shrinkage deformation, making it difficult to offset dimensional deviations at the source during the welding process.

[0005] When welding complex spatial structures, the threaded holes on the upper part of the frame, intended for later assembly, are enclosed within a narrow structure. Welding slag can easily fall into the threaded holes and cause blockages, and due to space constraints, secondary cleaning after welding is difficult. Furthermore, to control the frame tolerance within 0.2 mm, if online monitoring and intervention hardware is added to the fixture, conventional sensors and metal connecting rods are easily affected by strong arc radiation and high-temperature heat conduction near the welding area, leading to distorted detection signals or component failure, making it difficult to maintain stable precision control under harsh welding conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a frame welding and forming process and fixture for wafer manufacturing machines, which solves the problems of thermal deformation caused by uneven local heat input during the welding process, and structural elastic rebound and warping caused by the instantaneous release of mechanical constraints during the demolding and disassembly stage. At the same time, it solves the problems of internal hidden holes being easily blocked by welding spatter and conventional fixture monitoring hardware being easily interfered with and failing under high temperature and strong light conditions.

[0007] To address the above problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a rack welding and forming process for a wafer manufacturing machine, employing the following technical solution:

[0009] The rack welding and forming process of a wafer fabrication machine includes the following steps:

[0010] The surface of the frame structure to be welded is mechanically ground; the holes with enclosed spaces are pre-tapping and cleaned, and high-temperature resistant ceramic studs are pre-filled into the holes to obtain the pre-treated frame structure;

[0011] The pre-treated frame structure is placed on the fixture base, pre-inspected and adjusted using a laser flatness tester, the positioning template is closed, and an initial clamping force is applied through a flexible retracting clamping mechanism; when welding the base frame of the frame structure, the forced heat dissipation channel unit is activated to circulate cooling water.

[0012] When welding the top frame of the frame structure, the heating belt is activated to preheat the surrounding area and maintain a constant temperature. When welding special high-precision parts of the frame structure, the amount of thermal deformation displacement of the vertical plane is monitored in real time. When the amount of thermal deformation displacement reaches the monitoring threshold, a thrust is applied in the opposite direction of deformation through a piezoelectric ceramic actuator to compensate until the weld is completely solidified.

[0013] The temperature of the core weld zone is monitored while the welding is completed and the flexible relief clamping mechanism is not released. When the temperature of the frame structure drops to the trigger unloading threshold, the flexible relief clamping mechanism is instructed to execute a step-by-step pressure relief and creep release procedure until the initial clamping force drops to zero.

[0014] By adopting the above technical solution, through surface pretreatment of structural components and hole protection, differentiated heat flow control during collaborative welding, dynamic thrust compensation for local high-precision parts, and step-by-step pressure relief and creep release after welding, the effects of controlling the welding thermal deformation of the frame, eliminating residual stress, and ensuring the overall dimensional accuracy of the formed parts are achieved. The specific mechanism and steps are as follows:

[0015] Step 1: Hole Blockage Prevention and Protection. Before the welded joints form a closed space, the holes are tapped and filled with high-temperature resistant ceramic studs. The ceramic material has low thermal conductivity and a high melting point, preventing melting and thermal deformation in the high-temperature environment of welding. This prevents splashed metal particles from adhering deep into the hole, maintaining the integrity of the internal structure of the threaded hole.

[0016] Step 2: Controlling Temperature Field Distribution to Reduce Thermal Stress. Different parts of the frame have varying thicknesses and heat dissipation conditions. For the base frame welding, convective heat transfer is achieved by introducing circulating cooling water to remove heat transferred from the periphery of the molten pool to the base material, reducing the temperature peak in the base frame area. For the top frame welding, heating bands are used to preheat the surrounding area, reducing the temperature gradient difference between the molten pool and the base material. By controlling the local temperature of different component areas separately, the overall thermal expansion difference of the frame is reduced, thereby decreasing the thermal stress caused by temperature differences.

[0017] Step 3: Compensate for thermal strain with reverse mechanical load. The principle of metal welding deformation is that local expansion during heating is hindered by the surrounding cold metal, resulting in compressive plastic strain, and tensile residual stress is generated during cooling and solidification.

[0018] This solution monitors vertical plane displacement in real time during welding. Once the displacement due to thermal expansion or contraction reaches a threshold, the piezoelectric ceramic actuator is activated to apply a mechanical thrust load in the opposite direction. This mechanical load forces the generation of mechanical plastic strain in the opposite direction within a region of high temperature and decreased material yield strength. Since the total strain is the sum of thermal strain, elastic strain, and plastic strain, the introduction of reverse mechanical plastic strain can counteract the thermoplastic strain generated during the natural solidification of the weld, allowing the local area to maintain its original geometric dimensions after cooling.

[0019] Step 4: Stress relaxation and creep release. In conventional processes, the fixture is released directly after welding. Due to the sudden removal of the fixture constraint, the elastic strain energy accumulated inside is instantly converted into macroscopic deformation.

[0020] This process does not immediately unload after welding. Instead, based on the creep properties of materials at high temperatures, a stepped pressure reduction is performed as the temperature drops to the trigger threshold. Each pressure reduction, maintained for a certain period, allows residual stress within the structure to relax through minute plastic flows of the material under the corresponding clamping load. As the temperature decreases, the material's yield strength gradually recovers, at which point the clamping force is gradually reduced, maintaining a dynamic balance between the frame structure's contraction force and the external clamping force. Finally, upon complete pressure reduction, the accumulated internal thermal stress has been released through the creep process, preventing elastic rebound.

[0021] Preferably, the cleaning method is as follows: pre-welding cleaning is performed using anhydrous ethanol in conjunction with ultrasonic waves and then dried.

[0022] By adopting the above technical solution, anhydrous ethanol is used to dissolve oil stains and ultrasonic cavitation effect is used to remove surface deposits, eliminate organic residues in the weld area, and reduce the sources of weld porosity and cold cracks.

[0023] Preferably, the specific steps of the pre-detection and adjustment are as follows:

[0024] By adjusting the fine-tuning lifting mechanism located on the fixture base, the flatness tolerance of the frame structure is kept within the range of 0.05 to 0.15 mm when the initial clamping force is not applied.

[0025] By adopting the above technical solution, the initial clearance of structural components before clamping is limited. If clamping force is applied directly to close an excessively large assembly clearance without pre-adjustment, initial elastic strain energy will be generated inside the structure. During cooling and demolding, the superimposed welding residual stress can easily lead to structural deformation. Controlling the initial tolerance within the specified range can reduce the forced assembly stress.

[0026] Preferably, the flexible retraction clamping mechanism uses a proportional servo hydraulic cylinder; the initial clamping force ranges from 500 to 3000 N.

[0027] By adopting the above technical solution, the proportional servo hydraulic cylinder can provide a constant and dynamically adjustable output force compared to a rigid screw clamp. The initial clamping force of 500-3000N can overcome the initial gravitational deformation of the sheet metal and ensure that the connecting surfaces fit together. At the same time, it allows the hydraulic system to provide a small allowance when the structure expands due to heat, avoiding excessive local compressive stress that could lead to structural instability and buckling.

[0028] Preferably, the base frame welding adopts gas metal arc welding; the control parameters for the cooling water circulation are: the cooling water circulation is started before arc ignition, the water flow rate is set to 2.0~5.0L / min, and water is continuously supplied throughout the welding process.

[0029] By adopting the above technical solution, the arc heat of gas metal arc welding is large and the molten pool is deep. Starting the cooling circulation before arc ignition can establish a stable heat conduction steady-state channel at the bottom. The flow rate of 2.0 to 5.0 L / min matches the heat input of this process, and convective heat transfer is carried out through circulating water to control the grain growth rate and improve the mechanical toughness of the weld area.

[0030] Preferably, the top frame welding is performed using tungsten inert gas welding; the preheating control parameters are: the heating belt is activated before arc ignition to preheat the surrounding area to 100-200°C.

[0031] By adopting the above technical solution, the heat of tungsten inert gas (TIG) welding is concentrated. Preheating the periphery with a silicone heating strip reduces the heat transfer rate from the arc center to the periphery, decreases the unevenness of volume expansion during phase transformation, and reduces the tendency for microcracks to form in the structure.

[0032] Preferably, the control parameters for the thrust compensation are: when the detected thermal deformation displacement reaches a monitoring threshold of 0.05 to 0.08 mm, the thrust compensation of 0.1 to 0.2 mm is applied in the opposite direction of the deformation.

[0033] By adopting the above technical solution and setting the displacement monitoring threshold to 0.05–0.08 mm, timely intervention can be achieved during the micro-deformation stage. A compensation amount of 0.1–0.2 mm is applied, taking into account the stiffness loss during the transmission of mechanical thrust and the yielding displacement of high-temperature materials. This compensation displacement is used to offset the cooling contraction displacement of high-precision parts.

[0034] Preferably, the specific steps of the stepped pressure relief creep release procedure are as follows: when the temperature of the frame structure component drops to 150-250°C, perform 2 to 4 stages of pressure reduction creep release, and maintain pressure for 5 to 10 minutes after each stage of pressure reduction.

[0035] By adopting the above technical solution, 150–250℃ falls within the temperature range where the metallic material begins to significantly recover its strength. Within this temperature range, the load is reduced in stages and coordinated with the holding time. Utilizing the high-temperature creep characteristics of the material, the residual stress is relaxed through minute plastic deformation, thus matching the rate of pressure reduction with the rate of stress release.

[0036] Preferably, after demolding and release, the process further includes: using a coordinate measuring machine to perform dimensional inspection and fine-tuning cold correction on the released frame structure, and using surface dye penetrant testing to detect pores and cracks.

[0037] By adopting the above technical solution, the final deformation residual value is obtained through coordinate measuring machine measurement and a basis for cold correction is provided. Penetrant testing verifies that differentiated thermal management and creep stress release do not form opening defects on the structural surface, thus ensuring the quality of rack delivery.

[0038] Secondly, the present invention provides a frame welding and forming fixture for a wafer manufacturing machine, employing the following technical solution:

[0039] A rack welding and forming fixture for a wafer manufacturing machine, used in the aforementioned rack welding and forming process of the wafer manufacturing machine, including:

[0040] The basic support system includes a cast iron platform with T-slots on its surface, and rigid support columns distributed on the cast iron platform and equipped with a spiral fine-adjustment lifting mechanism.

[0041] The flexible retraction clamping system includes a positioning template and a proportional servo hydraulic cylinder;

[0042] The differentiated heat flow control system includes a copper water-cooled pad and internal microchannels installed on the basic support system, and a flexible silicone heating strip arranged on the positioning template.

[0043] The dynamic fine-tuning compensation mechanism includes an LVDT displacement sensor equipped with an anti-arc interference quartz glass micrometer probe and a piezoelectric ceramic actuator connected to a heat-insulating zirconia ceramic link.

[0044] The sensing and control system includes thermocouples and a PLC controller, wherein the PLC controller is communicatively connected to the flexible retraction clamping system, the differentiated heat flow control system and the dynamic fine-tuning compensation mechanism.

[0045] By adopting the above technical solution, a welding forming fixture integrating mechanical support, fluid heat transfer control, and electrical closed-loop servo compensation is provided, solving the technical challenges of high-precision frames in assembly, thermal deformation control, and demolding stress release processes. The specific working principle is as follows:

[0046] Firstly, the flexible yielding and pressure relief of the mechanical clamping. The cast iron platform in the basic support system provides a rigid support reference plane, while the spiral fine-tuning lifting mechanism provides precise adjustment of spatial posture to absorb initial machining errors of the structural components. The flexible yielding clamping system utilizes a proportional servo hydraulic cylinder for clamping. During the welding heating and expansion stage, the hydraulic system utilizes the compressibility of hydraulic oil and the dynamic overflow function of the servo valve to allow the structural components to expand and yield slightly while maintaining the clamping force, avoiding excessive compressive stress inside the sheet metal due to absolute rigid constraint, which could lead to instability and buckling. During the cooling stage, the proportional servo hydraulic cylinder reduces the clamping force in stages according to control commands, providing a decreasing external constraint condition for the creep relaxation of residual stress.

[0047] Secondly, heat flow control is implemented for different areas of the structure. A differentiated heat flow control system manages the rack temperature field through two sets of devices. A copper water-cooled pad is installed at the bottom; copper has excellent thermal conductivity, and the heat conducted from the molten pool in the rack is dissipated through forced convection heat transfer via circulating water in the microchannels, inhibiting grain growth in the heat-affected zone of the rack. Flexible silicone heating strips are distributed at the top, closely adhering to the structural surface for auxiliary heating. By combining bottom cooling with top preheating, the overall temperature gradient distribution of the rack is adjusted, reducing localized thermal stress concentration caused by uneven wall thickness and asymmetrical structure.

[0048] Thirdly, dynamic displacement compensation for high-precision local components. For special high-precision components of the frame, a dynamic fine-tuning compensation mechanism performs displacement monitoring and thrust compensation. LVDT displacement sensors collect minute displacements caused by thermal expansion in real time, and the PLC controller calculates and drives the piezoelectric ceramic actuator. When the piezoelectric ceramic material receives the control signal, it undergoes micron-level mechanical deformation, outputting a reverse compensation thrust to the deformed area, forcibly offsetting thermal strain within the metal's high-temperature plasticity range.

[0049] Fourth, photothermal isolation protection for the sensor components. The welding area is accompanied by high temperature and intense arc light. This fixture is equipped with a quartz glass micrometer probe at the displacement monitoring end. Utilizing the optical transmission and insulation properties of quartz glass, it avoids interference with the sensor signal caused by arc light. The thrust output end is connected to a zirconia ceramic connecting rod. Zirconia ceramic has low thermal conductivity and high compressive strength. While transmitting the compensating thrust, it cuts off the high-temperature conduction path from the weld to the piezoelectric ceramic element, preventing the piezoelectric ceramic material from decaying due to heat, and ensuring the accuracy of micro-displacement monitoring and the effectiveness of thrust load transmission.

[0050] In summary, the present invention has at least one of the following beneficial technical effects:

[0051] 1. In the differentiated welding process of the frame in different areas, this invention introduces specific heat transfer and mechanical intervention methods tailored to the structural characteristics of different parts. Forced heat dissipation is achieved by circulating cooling water in the base frame area, and preheating is performed using heating belts in the top frame area, reducing the temperature gradient difference between the upper and lower components of the frame. Simultaneously, for high-precision areas, horizontal displacement is monitored in real time under the positioning of the fixture template, and a reverse thrust is applied by the actuator for compensation. This process can directly offset thermal shrinkage displacement within the metal solidification zone of specific areas, controlling thermal deformation caused by varying thicknesses and asymmetrical structures, and ensuring the welding dimensional accuracy of special installation areas.

[0052] 2. This invention improves the positioning and clamping of the frame structure and the disassembly of the post-weld fixture. During the clamping stage, a servo hydraulic mechanism applies a flexible, yielding clamping force. During the post-weld cooling stage, a stepped pressure relief and creep release procedure is executed. During welding heating, the pipe is allowed to yield slightly due to heat to prevent buckling and yielding. During the post-weld cooling stage, the high-temperature creep characteristics of the metal are utilized to gradually relax the residual stress inside the structure as the clamping force decreases in stages. This method of smoothly unloading the constraint force avoids the elastic rebound and overall warping of the frame caused by the instantaneous disappearance of clamping force in conventional demolding operations.

[0053] 3. This invention optimizes the pre-treatment process before welding and the hardware structure of the special fixture. For holes that are difficult to machine, tapping is performed first, and high-temperature resistant ceramic studs are inserted. The high melting point of ceramics prevents welding spatter from adhering to and clogging the holes. Simultaneously, quartz glass and zirconia ceramic are used respectively at the sensor detection contact rod and thrust linkage of the fixture. This not only protects the integrity of the threads in the concealed space and reduces post-weld machining and cleaning processes, but also blocks the transmission path of the intense arc light and high temperature to the precision sensor components, ensuring the reliability of the fixture in monitoring and fixing the frame deformation during welding. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the architecture of an embodiment of the present invention;

[0055] Figure 2 This is a comparison of temperature and time change curves at different measuring points in the heat-affected zones of the chassis and top frame in an embodiment of the present invention. Sub-figure (a) is a temperature comparison figure of the chassis area, and sub-figure (b) is a temperature comparison figure of the top frame area.

[0056] Figure 3 This is a dual Y-axis curve diagram showing the dynamic displacement and reverse thrust compensation operation of the high-precision mounting plate during the local welding stage in an embodiment of the present invention.

[0057] Figure 4 The images show the synchronous dual Y-axis recordings of the temperature of the core area of ​​the frame and the clamping force of the servo hydraulic cylinder during the post-weld cooling and unloading stage in Embodiments 1-3 of the present invention. Sub-image (a) is the step yielding record of Embodiment 1, sub-image (b) is the step yielding record of Embodiment 2, and sub-image (c) is the step yielding record of Embodiment 3.

[0058] Figure 5 This is a bar chart comparing the measured values ​​of the form and position tolerances of the frame core processed in Examples 1-3 and Comparative Examples 1-4 of the present invention.

[0059] Figure 6 This is a grouped comparative bar chart of the peak residual stress test data of the key intersection nodes of the frame in this invention;

[0060] Figure 7 This is a mixed comparison chart of the number of structural flaws detected and the node ultimate tensile force along the double Y-axis in Examples 1-3 and Comparative Examples 1-4 of the present invention. Detailed Implementation

[0061] The following is in conjunction with the appendix Figure 1 -Appendix Figure 7 The present invention will be further described in detail below.

[0062] Examples 1-3:

[0063] Example 1:

[0064] This embodiment provides a wafer fabrication machine frame welding and forming process and fixture, including the following steps:

[0065] S1. Pre-welding treatment: Mechanically grind the 4mm thick square tube, base plate, partition, foot plate and high precision mounting plate to remove burrs at right angle joints and make the surface roughness Ra3.2μm.

[0066] For holes that form closed spaces after welding and are difficult to machine, pre-tapping is performed. Then, anhydrous ethanol is used in conjunction with ultrasonic cleaning and drying. High-temperature resistant ceramic studs are pre-filled inside the holes as a protection against blockage.

[0067] S2. Clamping, Positioning, and Introduction of the Basic Fixture: The pre-processed structural components (i.e., square tubes, base plates, partitions, foot plates, and high-precision mounting plates) are placed on the base of a dedicated fixture. The fixture base is a cast iron platform with T-slots on its surface, and rigid support columns with spiral fine-tuning lifting mechanisms are distributed on the base as basic support and reinforcement components. After placing the structural components, a laser flatness meter is used for pre-inspection. By adjusting the fine-tuning lifting mechanism, the flatness tolerance of each structural component is within 0.10mm when no clamping force is applied. Then, the positioning template is closed, and the flexible retraction clamping mechanism set on the fixture is activated. In this embodiment, the clamping mechanism uses a proportional servo hydraulic cylinder, and an initial clamping force of 1500N is applied through a PLC controller to ensure that the components fit tightly together.

[0068] S3. Differentiated thermal management and collaborative welding process:

[0069] S3.1: During the welding of the base frame, gas metal arc welding (GMAW) is used. A forced heat dissipation channel unit is simultaneously introduced and installed on the base frame support assembly. This unit consists of a copper water-cooled pad attached to the back of the base frame and internal microchannels. Cooling water circulation is initiated 45 seconds before arc ignition, with a water flow rate set at 3.5 L / min. Water is continuously supplied throughout the welding process to forcefully conduct and dissipate the large amount of heat.

[0070] S3.2: When welding the top frame, tungsten inert gas (TIG) welding is used. A localized heating unit for the top frame is introduced simultaneously, consisting of flexible silicone heating strips attached to the perimeter of the welding area. The heating strips are activated before arc initiation to preheat the area around the weld to 150°C and maintain this temperature. After welding, natural cooling is controlled to mitigate the temperature gradient.

[0071] S3.3: When performing localized welding on special high-precision parts (high-precision mounting plates), a dynamic fine-tuning compensation mechanism is introduced simultaneously and installed on the positioning template. This mechanism includes an LVDT displacement sensor with an anti-arc interference quartz glass micrometer probe and a piezoelectric ceramic actuator. During welding, the LVDT sensor monitors the vertical plane displacement in real time. When the detected thermal deformation displacement reaches 0.06mm, the PLC instructs the piezoelectric ceramic actuator to apply a 0.15mm thrust compensation in the opposite direction of deformation via a heat-insulated zirconia ceramic connecting rod, and maintains this reverse thrust until the weld section is completely solidified.

[0072] S4. Stepped Flexible Unloading: With welding completely completed and the proportional servo hydraulic cylinder still in place, the temperature of the core weld area is monitored via thermocouples. When the frame temperature drops to 200℃, the PLC controller instructs the servo hydraulic cylinder to execute a 3-stage pressure relief and creep release procedure:

[0073] First, the clamping force is linearly reduced from 1500N to 1050N and held for 8 minutes; then it is further reduced to 600N and held for 8 minutes; finally, when the frame temperature drops below 50℃, the clamping force is completely reduced to 0 to complete the demolding release.

[0074] S5. Full-dimensional quality inspection: After release, the frame is inspected and fine-tuned using a coordinate measuring machine, and surface dye penetrant testing (PT) is used to detect pores and cracks, and the tightness of each node connection is checked.

[0075] Example 2:

[0076] This embodiment provides a wafer fabrication machine frame welding and forming process and fixture, including the following steps:

[0077] S1. Pre-welding treatment: Mechanically grind the 2mm thick square tubes, base plates, partitions, foot plates and high-precision mounting plates to remove burrs at right-angle joints and make the surface roughness Ra3.2μm.

[0078] For holes that form closed spaces after welding and are difficult to machine, pre-tapping is performed. Then, anhydrous ethanol is used in conjunction with ultrasonic cleaning and drying. High-temperature resistant ceramic studs are pre-filled inside the holes as a protection against blockage.

[0079] S2. Clamping, Positioning, and Introduction of the Basic Fixture: The pre-treated structural components (i.e., square tubes, base plates, partitions, foot plates, and high-precision mounting plates) are placed on the base of a dedicated fixture. The fixture base is a cast iron platform with T-slots on its surface, and rigid support columns with spiral fine-tuning lifting mechanisms are distributed on the base as basic support and reinforcement components. Due to the thinness of the tubes, to prevent clamping deformation, a laser flatness tester is used for pre-inspection after the structural components are placed. The flatness tolerance of each structural component is kept within 0.05mm when no clamping force is applied by adjusting the fine-tuning lifting mechanism. Then, the positioning template is closed, and the flexible retraction clamping mechanism set on the fixture is activated. In this embodiment, the clamping mechanism uses a proportional servo hydraulic cylinder, and an initial clamping force of 500N is applied by the PLC controller for locking, so that the components fit tightly together.

[0080] S3. Differentiated thermal management and collaborative welding process:

[0081] S3.1: During the welding of the base frame, gas metal arc welding (GMAW) is used. A forced heat dissipation channel unit is simultaneously introduced and installed on the base frame support assembly. This unit consists of a copper water-cooled pad attached to the back of the base frame and internal microchannels. Due to the low overall heat input, cooling water circulation is initiated 45 seconds before arc ignition, with a water flow rate set at 2.0 L / min. Water is continuously circulated throughout the welding process to forcefully conduct and dissipate heat.

[0082] S3.2: When welding the top frame, tungsten inert gas (TIG) welding is used. A localized heating unit for the top frame is introduced simultaneously, consisting of flexible silicone heating strips attached to the perimeter of the welding area. The heating strips are activated before arc initiation to preheat the area around the weld to 100°C and maintain this temperature. After welding, natural cooling is controlled to mitigate the temperature gradient.

[0083] S3.3: When performing localized welding on special high-precision parts (high-precision mounting plates), a dynamic fine-tuning compensation mechanism is simultaneously introduced and installed on the positioning template. This mechanism includes an LVDT displacement sensor with an anti-arc interference quartz glass micrometer probe and a piezoelectric ceramic actuator. During welding, the LVDT sensor monitors the vertical plane displacement in real time. When the detected thermal deformation displacement reaches the monitoring threshold of 0.05mm, the PLC instructs the piezoelectric ceramic actuator to apply a 0.1mm thrust compensation in the opposite direction of deformation through a heat-insulated zirconia ceramic connecting rod, and maintains this reverse thrust until the weld section is completely solidified.

[0084] S4, Stepped flexible yield unloading:

[0085] With all welding completed and the proportional servo hydraulic cylinder still in place, the temperature of the core weld area is monitored via thermocouples. When the frame temperature drops to 150℃, the unloading procedure is triggered. The PLC controller instructs the servo hydraulic cylinder to shorten the pressure holding time and adjust the gradient to a two-stage pressure relief and creep release program.

[0086] First, linearly reduce the clamping force from 500N to 250N (i.e., 50%) and hold the pressure for 5 minutes; when the frame temperature drops below 50℃, directly reduce the clamping force to 0 to complete the demolding release.

[0087] S5. Full-dimensional quality inspection: After release, the frame is inspected and fine-tuned using a coordinate measuring machine, and surface dye penetrant testing (PT) is used to detect pores and cracks, and the tightness of each node connection is checked.

[0088] Example 3: This example provides a frame welding and forming process and fixture for a wafer manufacturing machine, including the following steps:

[0089] S1. Pre-welding treatment: Deep mechanical grinding is performed on the 6mm thick square tube, base plate, partition, foot plate and high precision mounting plate to remove burrs at right angle joints and make the surface roughness Ra3.2μm.

[0090] For holes that form closed spaces after welding and are difficult to machine, pre-tapping is performed. Then, anhydrous ethanol is used in conjunction with ultrasonic cleaning and drying. High-temperature resistant ceramic studs are pre-filled inside the holes as a protection against blockage.

[0091] S2. Clamping and Positioning and Introduction of Basic Fixtures:

[0092] The pre-processed structural components (i.e., square tubes, base plates, partitions, foot plates, and high-precision mounting plates) are placed on the base of a specialized fixture. The fixture base is a cast iron platform with T-slots on its surface, and rigid support columns with helical fine-tuning lifting mechanisms are distributed on the base as basic support and reinforcement components. Due to the high rigidity of the thick-walled structure, after placing the structural components, a laser flatness meter is used for pre-inspection. By adjusting the fine-tuning lifting mechanism, the flatness tolerance of each structural component is kept within 0.15mm without clamping force. Then, the positioning template is closed, and the flexible retraction clamping mechanism set on the fixture is activated. In this embodiment, the clamping mechanism uses a proportional servo hydraulic cylinder, and a maximum initial clamping force of 3000N is applied via a PLC controller for strong locking, ensuring a tight fit between the components.

[0093] S3. Differentiated thermal management and collaborative welding process:

[0094] S3.1: During the welding of the base frame, gas metal arc welding (GMAW) is used. A forced heat dissipation channel unit is simultaneously introduced and installed on the base frame support assembly. This unit consists of a copper water-cooled pad attached to the back of the base frame and internal microchannels. Cooling water circulation is initiated 45 seconds before arc ignition, with the water flow rate adjusted to 5.0 L / min. Water is continuously supplied throughout the welding process to forcefully conduct and dissipate the large amount of heat.

[0095] S3.2: When welding the top frame, tungsten inert gas (TIG) welding is used. A localized heating unit for the top frame is introduced simultaneously, consisting of flexible silicone heating strips attached to the perimeter of the welding area. The heating strips are activated before arc initiation to preheat the area around the weld to 200°C and maintain this temperature. After welding, natural cooling is controlled to mitigate the temperature gradient.

[0096] S3.3: When performing localized welding on special high-precision parts (high-precision mounting plates), a dynamic fine-tuning compensation mechanism is introduced simultaneously and installed on the positioning template. This mechanism includes an LVDT displacement sensor with an anti-arc interference quartz glass micrometer probe and a piezoelectric ceramic actuator. During welding, the LVDT sensor monitors the vertical plane displacement in real time. When the detected thermal deformation displacement reaches the monitoring threshold of 0.08mm, the PLC instructs the piezoelectric ceramic actuator to apply a thrust compensation of up to 0.2mm in the opposite direction of deformation via a heat-insulated zirconia ceramic connecting rod, and maintains this reverse thrust until the weld section is completely solidified.

[0097] S4. Stepped Flexible Unloading: With welding completely completed and the proportional servo hydraulic cylinder still in place, the temperature of the core weld area is monitored via thermocouples. When the frame temperature drops to 250℃, the PLC controller instructs the servo hydraulic cylinder to execute a 4-stage slow pressure relief and creep release procedure:

[0098] First, reduce the clamping force from 3000N to 2250N, 1500N, and 750N in sequence, and hold the pressure for 10 minutes after each reduction. Finally, when the frame temperature drops below 50℃, reduce the clamping force to 0 completely to complete the demolding release.

[0099] S5. Full-dimensional quality inspection: After release, the frame is inspected and fine-tuned using a coordinate measuring machine, and surface dye penetrant testing (PT) is used to detect pores and cracks, and the tightness of each node connection is checked.

[0100] Example 4:

[0101] This embodiment provides a fixture for the above-mentioned wafer manufacturing machine rack welding and forming process, such as... Figure 1 As shown, the specific structure is as follows:

[0102] Basic support system: This includes a base, which is a cast iron platform with T-slots on its surface. Multiple rigid support columns are distributed on the cast iron platform, serving as the basic support and reinforcement components for structural components such as the frame base plate, partitions, and pipes. Each rigid support column integrates a spiral fine-adjustment lifting mechanism, which, in conjunction with an external laser flatness gauge, is used to pre-adjust and ensure that the initial flatness of each structural component is within tolerance range without applying clamping force.

[0103] The flexible recoil clamping system includes a positioning template and a flexible recoil clamping mechanism. The positioning template is used to cover the frame structure placed on the base support system; the flexible recoil clamping mechanism is mounted on the fixture body, and in this embodiment, a proportional servo hydraulic cylinder is used. The proportional servo hydraulic cylinder is connected to the central control system and is used not only to apply an initial clamping force before welding to ensure tight contact and locking of the components, but also to execute a controllable step-by-step pressure relief and creep release procedure during the post-weld cooling stage.

[0104] Differentiated heat flow control system: including the base frame forced heat dissipation channel unit and the top frame local insulation and heating unit.

[0105] The forced heat dissipation channel unit is installed on the base support assembly of the aforementioned basic support system. It consists of a copper water-cooled pad attached to the back of the chassis and microchannels formed inside the pad. The microchannels are connected to a cooling water circulation pipeline with flow control, which is used to forcibly conduct and dissipate large amounts of heat during gas metal arc welding of the chassis.

[0106] The top frame local heat preservation and heating unit consists of flexible silicone heating strips attached to the periphery of the welding area of ​​the top frame. It is used to preheat and preserve the surrounding area during tungsten inert gas welding of the top frame and to control the natural cooling after welding.

[0107] Dynamic fine-tuning compensation mechanism: Installed on the positioning template, specifically designed for high-precision mounting plates and other special high-precision parts of the frame. This mechanism includes an LVDT displacement sensor and a piezoelectric ceramic actuator. The LVDT displacement sensor's probe end is equipped with an arc-interference-resistant quartz glass micrometer probe for real-time monitoring of thermal deformation displacement on the vertical plane. The thrust output end of the piezoelectric ceramic actuator is connected to a heat-insulating zirconia ceramic connecting rod. When the thermal deformation displacement reaches a set threshold, the piezoelectric ceramic actuator applies thrust compensation in the opposite direction of deformation through this ceramic connecting rod.

[0108] Sensing and Control System: Includes thermocouples and a PLC controller. Thermocouples are positioned in the core weld area for real-time temperature monitoring. The PLC controller's inputs are communicatively connected to the LVDT displacement sensor and thermocouples, while its outputs are controlled by the proportional servo hydraulic cylinder, piezoelectric ceramic actuator, water-cooled circulating pump valve of the base frame forced cooling channel unit, and the flexible silicone heating strip of the top frame, achieving closed-loop coordinated control of temperature monitoring feedback, dynamic thrust compensation, and stepped unloading.

[0109] Comparative Examples 1-4:

[0110] Comparative Example 1:

[0111] Compared to Example 1, the differences are: the base frame water cooling unit and the top frame heating unit are turned off, and the dynamic fine-tuning compensation mechanism in special parts is turned off; and in S4, after welding, a clamping force of 1500N is maintained until the frame is completely cooled to below 50°C, and then the clamping force is instantly reduced to 0. All other aspects are the same.

[0112] Comparative Example 2:

[0113] Compared to Example 1, the difference lies in that, in S3, the forced heat dissipation channel unit of the base frame and the local heat preservation and heating unit of the top frame are closed, allowing the frame to cool naturally through heat transfer. The remaining step-back and dynamic compensation steps are the same.

[0114] Comparative Example 3:

[0115] Compared to Example 1, the difference is that in S4, the "3-stage pressure relief and creep release procedure" executed based on temperature feedback is cancelled, and the traditional unloading method is adopted, that is, the initial clamping force of 1500N is kept locked after welding, and the clamping force is instantly reduced to 0 once the temperature drops below 50°C. All other aspects are the same.

[0116] Comparative Example 4:

[0117] Compared to Example 1, the difference lies in S3: for local welding of special high-precision parts (such as mounting plates), the LVDT sensor monitoring and piezoelectric ceramic actuator are turned off, and rigid static limiting is achieved solely by the contour holes of the positioning template, without applying reverse mechanical displacement compensation thrust. Everything else remains the same.

[0118] Test Examples 1-6:

[0119] Test Example 1: Monitoring Temperature Field Gradient and Cooling Rate

[0120] Test steps:

[0121] A K-type thermocouple with a diameter of 0.5 mm was selected as the temperature sensing element, and the lead end was connected to a multi-channel data acquisition instrument. The data sampling frequency of the system was set to 10 Hz.

[0122] During the frame assembly welding process in Example 1, temperature monitoring arrays were arranged in the gas metal arc welding area of ​​the bottom frame and the tungsten inert gas welding area of ​​the top frame, respectively. Using the set weld centerline as a reference, thermocouple measuring ends were fixed to the metal surface at positions 5mm, 15mm, and 30mm away from the centerline on the pipe surface perpendicular to the weld direction, respectively, using a capacitor energy storage spot welding machine.

[0123] Before igniting the welding arc, turn on the data acquisition instrument to record the background temperature. Mark the arc ignition zero point when the welding torch passes the section where the thermocouple is located. Continuously collect and record temperature change data until the overall temperature of the frame structure naturally drops or is forcibly cooled to below 50°C, at which point stop collecting data.

[0124] Export the raw data from the data acquisition system and extract the temperature values ​​of the base frame area and top frame area at specific time points for comparative analysis.

[0125] Test data:

[0126] Table 1. Temperature and Time Records of the Heat-Affected Zones of the Base and Top Frames in Example 1

[0127]

[0128] Test conclusion:

[0129] Combining the data in Table 1 with Figure 2 The temperature versus time curve shown indicates that... Figure 2 The horizontal axis of the two subplots represents the data acquisition time in seconds, and the vertical axis represents the temperature recorded at each measuring point in degrees Celsius.

[0130] observe Figure 2 Subplot (a) shows a large longitudinal spacing between the three curves at distances of 5mm, 15mm, and 30mm from the weld, indicating a sharp, non-linear decrease in the peak temperature of the gas metal arc welding zone of the underframe as the spatial distance increases. Under the forced heat conduction intervention of the copper water-cooled pad, the temperature curve at 30mm from the weld in subplot (a) remains essentially attached to the low-temperature range at the bottom of the graph after arc ignition (0s), rising only to 67.4℃ in 10 seconds and dropping to 28.4℃ at 120 seconds. The temperature curve at 5mm from the weld exhibits a very steep downward slope after reaching its peak, then quickly converges with the curve representing the far end. This indicates that the heat input during welding is strictly confined to a region of a few millimeters around the weld edge, without deep conduction along the longitudinal direction of the pipe. The confined heat-affected zone directly reduces the volume of thermally expanded material, physically reducing the heat source driving force for macroscopic bending deformation of the underframe structure.

[0131] observe Figure 2In subplot (b), under the preheating effect of the flexible silicone heating strip, the initial starting point (longitudinal intercept) of all three curves is raised to around 150℃. Ten seconds after arc ignition, the longitudinal temperature difference between the curves at 5mm and 30mm from the weld is 587.1℃. Compared to the extremely wide spacing of 765.3℃ at the same position on the base frame in subplot (a), the distribution of curves in subplot (b) is more compact, indicating a gentler spatial temperature gradient in the top frame area. Simultaneously, the slope of the temperature curves representing 5mm and 15mm from the weld in subplot (b) is significantly gentler than that of the base frame group.

[0132] The temperature in the near-zone of the top frame weld remained at 245.8℃ and 168.3℃ at 120 seconds and 300 seconds after arc initiation, respectively, exhibiting a low cooling rate. This low cooling rate characteristic prolongs the residence time of the weld metal in the high-temperature plastic stage, allowing the internal structure to release thermal stress caused by localized uneven heating through a slight creep mechanism. The slow cooling process delays the rapid phase transformation from austenite to martensite, reduces the microscopic volume shrinkage rate during crystallization and cooling phase transformation, and thus suppresses localized tensile stress and dimensional deviations in the top frame caused by cold shrinkage.

[0133] Comparing the high-gradient rapid heat conduction characteristics shown in subfigure (a) with the low-gradient gradual cooling characteristics shown in subfigure (b), it is shown that the forced heat dissipation of the base frame and the local preheating and slow cooling physical mechanism of the top frame in Example 1 are effective. Through the combination of the two, bidirectional control of the overall size and local accuracy of the frame is achieved.

[0134] Test Example 2: Dynamic Displacement and Anti-Deformation Thrust Monitoring and Analysis

[0135] Test steps:

[0136] Connect the data logger to the PLC communication interface of the fixture control system, configure it to read the real-time monitoring value register of the LVDT displacement sensor and the output command register of the piezoelectric ceramic actuator, and set the data sampling frequency to 50Hz.

[0137] In Example 1, when the high-precision mounting plate local welding process begins, the arc ignition command trigger time is used as the zero point for recording, and the data logger is started synchronously.

[0138] Continuously record parameter changes during the welding heating period, the molten pool formation period, and the initial solidification period after welding. Focus on capturing monitoring data before and after the accumulated heat deformation reaches the set threshold. The recording period continues until the weld section is completely solidified. The data capture time period is set to 0 to 45 seconds after arc ignition.

[0139] Export the background log file, filter the original monitoring values ​​of the LVDT displacement sensor corresponding to the time node, and the reverse compensation displacement values ​​actually output by the piezoelectric ceramic actuator at the synchronization time, and organize them into a comparison data table.

[0140] Test data:

[0141] Table 2. Dynamic Displacement and Reverse Compensation Operation Record of High-Precision Mounting Plate Welding in Example 1

[0142]

[0143] Test conclusion:

[0144] Combining the data in Table 2 with Figure 3 As shown, Figure 3 The horizontal axis represents the time after arc initiation, in seconds; the left vertical axis represents the LVDT integrated displacement monitoring value, in mm; and the right vertical axis represents the output displacement of the piezoelectric ceramic actuator, in mm.

[0145] observe Figure 3 The trend within the 0 to 23.4 second range shows a continuous upward trend in the curve representing the LVDT comprehensive displacement monitoring value, rising from 0.002 mm to 0.062 mm. This indicates that the high-precision mounting plate area underwent continuous outward thermal expansion deformation under the influence of welding heat input. During this stage, the curve representing the output displacement of the piezoelectric ceramic actuator on the right remains at the zero baseline.

[0146] When the horizontal axis reaches 23.4 seconds, the LVDT integrated displacement monitoring value curve breaks through the monitoring threshold of 0.06 mm. Subsequently, at 23.6 seconds, the output displacement of the piezoelectric ceramic actuator experiences a vertical step jump, rising to 0.153 mm. Simultaneously affected by the superposition of this physical thrust, the left-side LVDT integrated displacement monitoring value curve exhibits a reverse vertical abrupt change, with the value instantly crossing zero and dropping to -0.089 mm. The abrupt change characteristics of the two sets of curves at this node indicate that when the thermal deformation reaches the critical point, the dynamic fine-tuning compensation mechanism applies forced mechanical displacement intervention in the opposite direction of deformation.

[0147] Within the interval from 23.6 seconds to 42.7 seconds in the graph, the output displacement of the piezoelectric ceramic actuator maintains a gradual extension around the 0.15mm scale. Correspondingly, the LVDT integrated displacement monitoring value curve runs stably in the negative range below the horizontal axis. This time period corresponds to the pasty zone stage where the weld metal transforms from a liquid molten pool to solid crystallization. During this stage, the tensile strength and yield strength of the metal material are extremely low, and the continuous reverse thrust applied by the piezoelectric ceramic forces negative displacement strain in the structure surrounding the weld. The weld metal completes internal crystallization and physical solidification under this forced reverse strain state.

[0148] Observing the trend of the LVDT displacement curve extending from 34.5 seconds to 42.7 seconds, the value slowly changes from -0.081 mm to -0.103 mm, reflecting the material gradually entering the cooling and contraction period. The reverse mechanical deformation input into the structure through the step thrust in the early stage offsets the cooling contraction caused by the temperature drop in the later stage. The displacement vectors in opposite directions neutralize each other at the solidification level of the structure, blocking the macroscopic dimensional deviation caused by the accumulation of unidirectional thermal expansion and contraction. The coordinated trend of the process data and the hyperbola confirms the inherent logic of the reverse prestressing field compensation mechanism during solidification under operating conditions, and verifies the feasibility of applying mechanical reverse deformation force to control local flatness.

[0149] Test Example 3: Simultaneous Monitoring of Temperature and Stress Rheology

[0150] Test steps:

[0151] The data acquisition terminal is connected to the fixture PLC system and thermocouple temperature acquisition module through the control bus interface. The sampling frequency is set to 1Hz, and the background operation log file of the post-weld cooling and unloading stage is extracted synchronously.

[0152] Configure the data terminal to read three variables: the temperature of the core weld zone of the workpiece, the actual output clamping force of the servo hydraulic cylinder, and the cumulative running time of the system.

[0153] Dynamic monitoring data were extracted from Examples 1, 2, and 3, from the completion of the welding process and the cessation of heat input until the frame temperature naturally dropped to 50°C and the mold was completely released.

[0154] After exporting the data, feature data is extracted according to the trigger nodes and pressure holding end nodes of each yielding stage, and organized into a synchronous correspondence table of temperature decrease over time and clamping force step yielding.

[0155] Test data:

[0156] Table 3. Temperature and pressure monitoring data during the post-weld cooling and unloading stage in Examples 1-3

[0157]

[0158] Test conclusion:

[0159] Combining the data in Table 3 with Figure 4 As shown in the synchronous monitoring curve, Figure 4 The horizontal axis represents the cumulative time after welding is completed, in minutes; the left vertical axis corresponds to the core area temperature, in degrees Celsius, and is drawn as a continuous solid line; the right vertical axis corresponds to the actual clamping force, in nits (N), and is drawn as a stepped dashed line.

[0160] observe Figure 4The neutron graph (a) shows that the solid line representing temperature decays non-linearly over time. When the horizontal axis reaches the 11.2-minute mark, the temperature scale corresponding to the solid line drops to 199.4℃. At this point, the dashed line representing the clamping force experiences its first vertical downward step, dropping from 1493N and then horizontally extending to maintain around 1048N, entering the first yielding and pressure-holding stage. When the solid line touches the 145.2℃ scale at 27.4 minutes, the dashed line experiences a second downward step, maintaining the clamping force at 595N. The graph data and curve shape indicate that within the temperature range of 150℃ to 250℃, the servo hydraulic cylinder breaks the rigid lock-up state of traditional processes and performs multi-stage unloading.

[0161] In the intermediate temperature range of 150℃ to 250℃, metallic materials retain a certain degree of microplasticity, and their yield strength remains at a low level. By progressively reducing the external clamping constraint force, the internal thermal stress, previously suppressed by the rigid clamp, breaks through the current clamping resistance limit. The internally accumulated elastic strain energy is transformed into micro-plastic rheological processes such as dislocation slip and grain boundary sliding under this semi-constrained state. This rheological process consumes the stress sources that would otherwise trigger macroscopic deformation at the microscopic level.

[0162] Comparing the curves of Example 2 and Example 3, Figure 4 Neutron diagram (b) reflects the adjustments made in Example 2 for low-rigidity pipe conditions. The first downward step of the dashed line in the diagram is delayed until the solid temperature line reaches 149.6°C, the clamping force drops to 247N, and the subsequent horizontal line segment representing the pressure holding stage is shorter, corresponding to a shortened pressure holding period. Figure 4 Neutron diagram (c) reflects the operating status of the thick-walled, high-rigidity structure in Example 3. Due to the large internal residual thermal stress, the number of step-down steps in the dashed line increases. When the solid temperature line triggers the first step at 248.9°C, the dashed line then exhibits a clear three-stage step-down structure, with the clamping forces stabilizing successively at 2246N, 1494N, and 746N. The lateral span of the overall unloading cycle is extended to 45.2 minutes.

[0163] The differences in the starting nodes, descent drops, and flight widths of the dashed steps in different subgraphs reflect that parameter adjustments based on temperature feedback matched the rheological windows of the material under different heat storage and rigidity conditions. When the solid lines representing temperatures in each group finally dropped below the 50°C mark, the dashed lines representing clamping forces all returned to zero. The elastic strain energy accumulated inside the structure had already been dissipated in the earlier intermediate-temperature rheological stage, eliminating the kinetic energy conditions for instantaneous rebound and torsion of the structure caused by removing the clamping force at room temperature. The synchronous evolution of the monitoring data and curves confirmed the physical implementation process and feasibility of the stress creep release mechanism under thermoelastic conditions.

[0164] Test Example 4: Core Geometric Tolerance Inspection

[0165] Test steps:

[0166] After demolding and release, the frames of each embodiment and comparative example were uniformly moved into a precision constant temperature testing chamber with an ambient temperature controlled at 20±1℃ and left to stand for 48 hours to allow the internal temperature of the structure to reach thermal equilibrium with the ambient temperature, thereby eliminating the interference of residual temperature gradient on the metal volume morphology.

[0167] A bridge-type coordinate measuring machine was used as the testing equipment. The frame was placed on the granite measuring platform in the set direction, with the bottom supported by a three-point foundation. No pressure plates or clamps were applied, keeping the sample in a free state without external constraints.

[0168] The measurement software is used to establish the workpiece's basic coordinate system. Measurement paths are planned on the four main load-bearing planes of the base and top frames, with a grid spacing of 50mm × 50mm. The probe is controlled to perform discrete point pressure sampling, with a total of no less than 200 sampling points. The software fits the reference plane using the least squares method, calculates the peak-valley containment difference between the distribution intervals of each measurement point, and obtains the overall flatness and torsion values ​​of the frame.

[0169] A high-sensitivity ruby ​​probe with a diameter of 1mm was used to perform specialized testing on the area where the high-precision mounting plate was located. A dense grid scanning path with a spacing of 5mm was planned on the surface of the mounting plate, and the vertical extreme values ​​between all deformation abrupt points on the local surface and the reference fitting surface were extracted. The local limit form and position tolerance values ​​of the mounting plate were recorded.

[0170] Repeat the above steps to complete the measurement of all samples in Examples 1-3 and Comparative Examples 1-4, export the original inspection report generated by the system background, and extract two core dimensional feature data for comparison list.

[0171] Test data:

[0172] Table 4. Measurement data of core form and position tolerances of the frame in the examples and comparative examples

[0173]

[0174] Test conclusion:

[0175] Combining the data in Table 4 with Figure 5 As shown, Figure 5 The horizontal axis corresponds to different test groups, and the vertical axis represents the measured values ​​of geometric tolerances in mm. Figure 5 The height of the dark gray inner column represents the extreme values ​​of overall flatness and torsion, while the height of the light gray column represents the local limit tolerance of the mounting plate, showing the differences in the degree of dimensional distortion of each group at both the macroscopic and microscopic scales.

[0176] observe Figure 5In the data distribution areas of Examples 1 to 3, both types of columns are at extremely low heights. The height of the dark gray columns, representing overall extreme values, is controlled within the range of 0.13 mm to 0.24 mm, while the height of the light gray columns, representing local extreme values, remains between 0.05 mm and 0.08 mm. The column height distribution characteristics indicate that, under the combined effects of differentiated heat flux distribution, dynamic reverse thrust compensation, and stepped unloading creep program, the frame structure maintains its dimensional and positional accuracy both macroscopically and locally after experiencing high heat input and rapid phase change.

[0177] Comparative Example 1 corresponds to the traditional rigid clamping and natural cooling unloading process. Figure 5 In this group, the dark gray column height reached the largest in the entire field at 3.14 mm, while the light gray column height reached 0.82 mm, exhibiting three-dimensional spatial distortion. Comparative Example 3, while retaining thermal management control, eliminated the stepped pressure relief and creep release procedure; the chart shows its dark gray column height was 2.92 mm. The difference in the bar chart proves that the instantaneous removal of clamping force when cooling to room temperature after welding caused the elastic strain energy confined within the material to lose its constraint boundary, instantly converting into kinetic energy and triggering structural springback. The lack of a rheological dissipation process in the mid-temperature range led to excessive macroscopic deformation of the structure.

[0178] Comparative Example 2 eliminated the forced water cooling of the base frame and the preheating and slow cooling intervention of the top frame. In the figure, the height of the dark gray column in this group reaches 1.87 mm, higher than that of the example group. The height difference in the graph indicates that when heat is deeply conducted in the base frame and undergoes rapid cooling and contraction in the top frame, the increase in internal stress caused by uneven heating of the material exceeds the compensation limit of the subsequent stepped unloading procedure. Disordered diffusion at the heat source boundary is a precursor variable inducing structural foundation distortion.

[0179] Comparative Example 4 retains the thermal management control and stepped unloading program, but disables the piezoelectric ceramic dynamic thrust compensation in high-precision parts. Figure 5 The height of the dark gray column in this group is 0.21 mm, the same as the example group. However, the height of the light gray column, representing a local extreme value, suddenly increases to 0.69 mm, indicating a local loss of precision control. The contrast in column height within the same group verifies that the rigid static limit of the positioning template cannot resist the microscopic phase transformation tensile stress generated during the solidification and shrinkage of the molten pool. Without the intervention of reverse displacement pre-strain applied by piezoelectric ceramics, the high-precision parts undergo irreversible unidirectional micro-yield shrinkage at the moment of solidification. The data degradation of the light gray column confirms the role of LVDT monitoring and the piezoelectric ceramic intervention mechanism in ensuring local special precision, and the physical compensation thrust neutralizes the microscopic solidification shrinkage vector.

[0180] Test Example 5: Numerical Test of Residual Stress at Critical Nodes

[0181] Test steps:

[0182] The demolding frames of each group to be tested were fixed on the testing platform of the X-ray residual stress measuring instrument, and the zero point of the goniometer and the diffraction parameters of the instrument were calibrated using stress-free standard powder samples.

[0183] The heat-affected zone of the weld at the T-junction of the main load-bearing pipes of the base frame and the corner weld junction of the top frame were selected as stress test nodes. Constant potential electrolytic polishing process was used to remove the oxide layer and micro-processing marks on the surface of the test nodes. The polishing depth was controlled at about 0.15 mm to avoid introducing additional surface work hardening stress introduced by traditional mechanical grinding.

[0184] The scanning operation was performed using the sin²ψ method in X-ray diffraction. The goniometer was adjusted so that the X-ray beam irradiated the test nodes at multiple different ψ angles within the range of 0° to 45°. The detector synchronously recorded the diffraction peak shift parameters caused by the change in interplanar spacing at different tilt angles.

[0185] The diffraction angle shift is extracted based on the Bragg equation, and the extreme values ​​of surface residual stress in the test node region are calculated by combining the elastic modulus and Poisson's ratio parameters of the material matrix. If the test result is positive, it is counted as tensile stress; if it is negative, it is counted as compressive stress.

[0186] The calibration node measurements of all rack samples in Examples 1 to 3 and Comparative Examples 1 to 4 were completed in sequence. The residual stress peak values ​​of each node output by the system were compiled to form a comparative data list.

[0187] Test data:

[0188] Table 5. Test data of peak residual stress at key intersections of the frame

[0189]

[0190] Test conclusion:

[0191] Combining the data in Table 5 with Figure 6 As shown, Figure 6 The horizontal axis corresponds to different test groups, and the vertical axis corresponds to the peak residual stress measured by X-ray diffraction, with units of MPa. In the figure, the dark gray bars represent the residual stress at the junction of the base frame and the light gray bars represent the residual stress at the junction of the top frame. The height of the two sets of bars directly reflects the distribution level of residual stress within each group.

[0192] observe Figure 6In the distribution areas of Examples 1 to 3, both dark gray and light gray columns are in the lower height range, with measured values ​​ranging from +29.7 MPa to +51.4 MPa. The column height distribution characteristics reflect that during welding and subsequent cooling, the residual elastic strain energy accumulated inside the frame has been dissipated through the synergistic intervention of the stepped pressure relief creep release procedure and local preheating and slow cooling. The pressure holding and yielding during the intermediate temperature stage allows the material to obtain a plastic rheological window, restoring the microcrystalline lattice distortion and preventing the high-stress state from being frozen inside the room-temperature solid metal.

[0193] Observing the column shapes in Comparative Examples 1 and 3 in the chart, they exhibit a high-level state. Comparative Example 1 corresponds to the traditional manufacturing process without intervention, with its dark gray and light gray columns reaching heights of +345.8 MPa and +312.4 MPa, respectively. Comparative Example 3 involves thermal management control but eliminates the stepped unloading procedure, resulting in column heights of +328.7 MPa and +298.2 MPa. These two sets of high-value columns demonstrate that under rigid constraints and rapid cooling, the thermal shrinkage deformation of the material is suppressed, causing the volume shrinkage generated by the cooling phase transformation to be converted into elastic tensile distortion of the internal lattice. The peak tensile stress confined within the material constitutes a potential deformation hazard in later service life. Under external working loads or environmental temperature fluctuations, it is prone to exceeding the material's yield limit, leading to continuous creep or fatigue cracking of the structure.

[0194] Figure 6 In Comparative Example 2, the heights of the dark gray and light gray columns reached +276.3 MPa and +241.9 MPa, respectively. Due to the lack of heat distribution control, the heat accumulation in the base frame and the cold contraction of the top frame exacerbated the stress difference in the overall structure, resulting in column heights exceeding those of the Example group. In Comparative Example 4, the fine-tuning compensation of the high-precision parts was turned off. The column heights in the figure were +68.5 MPa and +55.2 MPa, respectively. The overall stress level was within a relatively controlled range, but still slightly higher than that of the Example group. The distribution of column height differences in each group in the chart verifies the operating mechanism of heat flow beam guidance and forced reverse strain physical compensation in reducing the microscopic residual stress field of the structure.

[0195] Test Example 6: Non-destructive testing pass rate and mechanical pull-out assessment

[0196] Test steps:

[0197] Oil and spatter were removed from the main load-bearing welds and the surrounding welds of the high-precision mounting plates of each group of frames using cleaning agents. A coloring penetrant was then evenly sprayed onto the test area. After standing for 15 minutes, excess penetrant was cleaned off and a developer was sprayed on the surface. The number of surface defects such as microcracks, pores, and lack of fusion was recorded.

[0198] An ultrasonic coupling agent was applied to the weld surface of the frame, and a phased array ultrasonic flaw detector was used to inspect the internal fusion state according to the standard scanning path. The number of internal defects exceeding the set equivalent standard was extracted, and the overall pass status of each frame flaw detection was statistically analyzed in conjunction with industry standards.

[0199] Typical T-shaped nodes and corner connection nodes processed under the same technological conditions from each group were selected to prepare standardized mechanical tensile test specimens. The two ends of the specimens were clamped in the upper and lower jaws of a servo universal testing machine, ensuring that the tensile axis was aligned with the stress center of the weld.

[0200] Set the constant tensile rate of the testing machine to 5 mm / min, start the tensile loading program, and continue until the weld or heat-affected zone of the specimen completely fractures. The system automatically records the peak value of the ultimate tensile force during the failure process.

[0201] The data on the number of penetration defects, the ultrasonic flaw detection qualification status, and the ultimate breaking tensile force were compiled into a multi-dimensional structural performance evaluation table.

[0202] Test data:

[0203] Table 6. Statistics of Frame Flaw Detection Defects and Nodal Pull-out Strength Data in Examples and Comparative Cases

[0204]

[0205] Test conclusion:

[0206] Combining the data in Table 6 with Figure 7 As shown, Figure 7 The horizontal axis corresponds to different test groups. The left vertical axis represents the ultimate tensile strength at the nodes, in kN, and the right vertical axis represents the number of surface defects detected on the PT, in units of locations.

[0207] observe Figure 7 The data distribution characteristics of Examples 1 to 3 show that the broken lines representing the number of detected defects all run close to the bottom zero point, and the corresponding UT ultrasonic flaw detection status is generally qualified. The height of the gray-scale bars representing the ultimate breaking tensile force is distributed in the range of 147.6kN to 161.8kN. The chart pattern confirms that after undergoing dynamic reverse thrust compensation and complex heat flow distribution intervention, the frame structure did not produce defects such as microcracks, pores, or lack of fusion. The stress strength of the basic structure is comparable to that of conventional processes and even slightly improved.

[0208] In the mushy stage, the weld metal is at the critical point of transition from liquid to solid. At this time, the piezoelectric ceramic actuator applies a reverse physical displacement on the order of 0.15 mm, forcing the metal to undergo slight forced deformation during crystallization and solidification. This displacement intervention occurs during a rheological window period when the metal material has extremely low tensile strength and high fluidity. Under the thrust intervention, the metal grains complete internal rearrangement and connection without physical tearing of the atomic bond layers. The measured flaw detection line smoothness and pull-out column height verify that the mechanical intervention applied by the dynamic fine-tuning mechanism does not damage the internal density and mechanical strength of the weld.

[0209] Figure 7 The broken line in the comparative examples shows a significant upward abrupt change, while the corresponding grayscale column height decreases. Comparative Example 1, using a traditional welding and natural cooling unloading process, shows two surface defects detected at the marked points on its broken line, and the grayscale column height drops to 143.5 kN. Comparative Example 3 retains thermal management control but eliminates the stepped unloading release procedure; its broken line reaches the highest point in the entire field, four surface defects are detected, ultrasonic testing shows local over-limits, and the grayscale column drops to the lowest point in the entire field at 138.9 kN. The two sets of comparative data indicate that under rigid constraints, experiencing heat input and rapid cooling, followed by instantaneous removal of the fixture at room temperature, the accumulated thermal shrinkage stress within the material easily exceeds the bonding force of local grain boundaries, inducing microscopic thermal cracks on the surface or near the surface.

[0210] The difference in bar shape between the examples and the comparative examples in the chart verifies the effectiveness of the stepped unloading creep release mechanism in alleviating internal constraint stress. Stress dissipation in the mid-temperature range reduces the cracking sensitivity during the metal cooling stage and eliminates microscopic damage caused by transient loosening. Simultaneous measurement results of the number of flaws and the ultimate tensile strength confirm that the manufacturing process based on reverse prestressing field compensation and stress creep improves the structural form and position accuracy while ensuring the structural foundation strength.

Claims

1. A frame welding and forming process for a wafer manufacturing machine, characterized in that, Includes the following steps: The surface of the frame structure to be welded is mechanically ground, and the holes with enclosed spaces are tapped and cleaned. High-temperature resistant ceramic studs are pre-filled into the holes to obtain the pre-treated frame structure. The pre-treated frame structure is placed on the fixture base, pre-inspected and adjusted using a laser flatness tester, the positioning template is covered, and an initial clamping force is applied through a flexible retraction clamping mechanism. When welding the base frame of the frame structure, the forced heat dissipation channel unit is activated to circulate cooling water. When welding the top frame of the frame structure, the heating belt is activated to preheat the surrounding area and maintain a constant temperature. When welding special high-precision parts of the frame structure, the amount of thermal deformation displacement on the vertical plane is monitored in real time. When the amount of thermal deformation displacement reaches the monitoring threshold, the piezoelectric ceramic actuator applies a thrust in the opposite direction of deformation to compensate until the weld is completely solidified. After all welding is completed and the flexible collapsible clamping mechanism is not loosened, the temperature of the core weld zone is monitored. When the temperature of the frame structure drops to the trigger unloading threshold, the flexible collapsible clamping mechanism is instructed to execute a stepped pressure relief and creep release procedure until the initial clamping force drops to 0, thus completing the demolding release.

2. The wafer manufacturing machine frame welding and forming process according to claim 1, characterized in that, The specific cleaning method is as follows: Pre-welding cleaning and drying were performed using anhydrous ethanol and ultrasonic cleaning.

3. The wafer manufacturing machine frame welding and forming process according to claim 1, characterized in that, The specific steps for the pre-detection and adjustment are as follows: By adjusting the fine-tuning lifting mechanism located on the fixture base, the flatness tolerance of the frame structure is kept within the range of 0.05 to 0.15 mm when the initial clamping force is not applied.

4. The wafer manufacturing machine frame welding and forming process according to claim 1, characterized in that, The flexible retraction clamping mechanism uses a proportional servo hydraulic cylinder, and the initial clamping force of the proportional servo hydraulic cylinder is in the range of 500 to 3000 N.

5. The wafer manufacturing machine frame welding and forming process according to claim 1, characterized in that, The base frame is welded using gas metal arc welding (GMAW), and the control parameters for the cooling water circulation are as follows: Before arc initiation, the cooling water circulation is turned on, and the water flow rate is set to 2.0 to 5.0 L / min, and water is continuously supplied throughout the welding process.

6. The wafer manufacturing machine frame welding and forming process according to claim 1, characterized in that, The top frame welding is performed using tungsten inert gas welding, and the preheating control parameters are as follows: Before arc initiation, the heating belt is activated to preheat the surrounding area to 100-200°C.

7. The wafer manufacturing machine frame welding and forming process according to claim 1, characterized in that, The control parameters for thrust compensation are: When the detected thermal deformation displacement reaches the monitoring threshold of 0.05 to 0.08 mm, a thrust compensation of 0.1 to 0.2 mm is applied in the opposite direction of deformation.

8. The frame welding and forming process of the wafer manufacturing machine according to claim 1, characterized in that, The specific steps of the stepped pressure relief and creep release procedure are as follows: When the temperature of the frame structure drops to 150-250°C, perform 2 to 4 stages of pressure reduction and creep release, and maintain pressure for 5 to 10 minutes after each stage of pressure reduction.

9. The frame welding and forming process of the wafer manufacturing machine according to claim 1, characterized in that, After demolding and release are complete, the following are also included: The released frame structure was subjected to dimensional inspection and fine-tuning cold correction using a coordinate measuring machine, and surface dye penetrant testing was used to detect porosity and cracks.

10. A frame welding and forming fixture for a wafer manufacturing machine, characterized in that, The rack bonding and forming process applied to the wafer manufacturing machine according to any one of claims 1-9 includes: The basic support system includes a cast iron platform with T-slots on its surface, and rigid support columns distributed on the cast iron platform and equipped with a spiral fine-adjustment lifting mechanism. The flexible retraction clamping system includes a positioning template and a proportional servo hydraulic cylinder; The differentiated heat flow control system includes a copper water-cooled pad and internal microchannels installed on the basic support system, and a flexible silicone heating strip arranged on the positioning template. The dynamic fine-tuning compensation mechanism includes an LVDT displacement sensor equipped with an anti-arc interference quartz glass micrometer probe and a piezoelectric ceramic actuator connected to a heat-insulating zirconia ceramic link. The sensing and control system includes thermocouples and a PLC controller, wherein the PLC controller is communicatively connected to the flexible retraction clamping system, the differentiated heat flow control system and the dynamic fine-tuning compensation mechanism.

Images