A sealing welding tool and method for a lubricating oil metal debris sensor

Abstract

The application provides a sealing welding tool and method for a lubricating oil metal chip sensor, which comprises a base, a fixed support, a movable support and a pressing support arranged in sequence from left to right on the upper surface of the base, and the sensor is clamped between the fixed support and the movable support; the sensor comprises a sensor main body, a through pipe and a to-be-welded flange; the left to-be-welded flange is connected with a first connecting piece, and the end of the first connecting piece is arranged on the fixed support; the right to-be-welded flange is connected with a second connecting piece, and the end of the second connecting piece is arranged on the movable support; a detection channel is arranged in the second connecting piece; a pressing device is installed on the pressing support, so that the both ends of the through pipe are radially contracted and respectively embedded in the inner holes of the corresponding to-be-welded flanges to realize interference fit. The sealing detection, positioning, pressing and welding support functions are integrated in one, and all processes can be completed at one time; through the sealing detection before welding, the rework or scrapping problem caused by oil leakage after welding can be fundamentally avoided.

Description

Technical Field

[0001] This invention belongs to the field of sensor manufacturing technology, and in particular relates to a sealing welding fixture and method for a lubricating oil metal shavings sensor. Background Technology

[0002] The lubricating oil metal shavings sensor is a precision sensor used to detect metal shavings in lubricating oil pipelines. It is widely used in high-end equipment fields such as aero-engines, gas turbines, marine power systems, wind turbine generators, and construction machinery. By monitoring the content and size distribution of metal particles in the lubricating oil, this sensor can assess the wear condition of mechanical equipment in real time, providing crucial data for equipment health management, fault prediction, and preventative maintenance.

[0003] However, traditional lubricating oil metal shavings sensor probes primarily use threaded connections to link the body and flange, a method with several technical drawbacks. First, threaded connections result in a larger overall sensor size, leading to poor installation adaptability, especially in space-constrained environments such as aero-engines, limiting installation location options. Second, threaded connections are prone to loosening under complex conditions such as long-term vibration, thermal cycling, and pressure pulsation, resulting in a high risk of seal failure, which is one of the most significant failure modes for this type of sensor. Furthermore, threaded connections exhibit poor aesthetic consistency, affecting product appearance, and have higher manufacturing costs, requiring specialized thread processing equipment and sealing elements.

[0004] To address the aforementioned issues and improve sensor reliability, size, and appearance, existing technologies employ welding to permanently connect the sensor body and flange. However, the application of welding also presents new technical challenges: pre-welding sealing cannot be verified, leading to the risk of post-weld oil leakage; high welding positioning accuracy is required, which traditional tooling struggles to meet; achieving a seal with dissimilar materials (such as metal and PEEK) is challenging, and controlling welding stress and thermal deformation is difficult.

[0005] The through-tube of the lubricating oil metal shavings sensor is made of high-performance engineering plastics such as PEEK (polyetheretherketone), while its body and flange are made of stainless steel or other metals. Due to the significant difference in thermal expansion coefficients between PEEK and metals, and the fact that PEEK is not weldable, effectively protecting the PEEK through-tube from heat damage and ensuring a tight seal between the through-tube and the metal flange during welding (where local temperatures can reach over 1400℃) presents a significant technical challenge. Traditional sealing solutions, such as O-ring seals and adhesive seals, either increase the number of parts and cost or fail to meet high reliability requirements. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention aims to propose a sealing welding fixture and method for a lubricating oil metal shavings sensor, which solves the problems that existing sealing welding fixtures cannot meet the requirements for pre-welding sealing testing and the inability to effectively seal between the PEEK pipe and the metal flange.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A sealing welding fixture for a lubricating oil metal shavings sensor includes a base. From left to right, a fixed bracket, a movable bracket, and a clamping bracket are arranged on the upper surface of the base. The sensor is clamped between the fixed bracket and the movable bracket, and the movable bracket is slidably connected to the base. The sensor includes a sensor body, a through pipe disposed within the sensor body, and welding flanges disposed on both sides of the sensor body; wherein, the left welding flange is connected to a first connecting member, the end of the first connecting member being placed on a fixed bracket; the right welding flange is connected to a second connecting member, the end of the second connecting member being placed on a movable bracket; The second connector is provided with a detection channel. The inlet of the detection channel is used to connect to a barometric pressure testing device, and the outlet of the detection channel is connected to the inner cavity of the sensor to perform airtightness testing on the sensor. A clamping device is installed on the clamping bracket. The clamping device is used to apply axial pressure to the second connecting piece, so that the flange to be welded is axially clamped to the sensor body, and the two ends of the PEEK material pipe are radially contracted and respectively embedded into the inner hole of the corresponding flange to be welded to achieve an interference fit.

[0008] Furthermore, both flanges to be welded are provided with a first inner hole and a second inner hole connected in sequence at the end near the sensor body, wherein the diameter of the first inner hole is larger than the diameter of the second inner hole; both ends of the through pipe are provided with protrusions that cooperate with the first inner hole, the end of the through pipe is used to be embedded in the second inner hole, and the outer diameter of the end of the through pipe is larger than the diameter of the second inner hole.

[0009] Furthermore, the first inner wall of both flanges to be welded is provided with a sealing groove for installing a sealing ring, and a sealing ring is provided at the connection between the two flanges to be welded and the first and second connecting parts.

[0010] Furthermore, the outer diameter of the end of the through pipe is in the range of 10.00mm to 10.03mm, and the diameter of the second inner hole of the flange to be welded is 9.92mm.

[0011] Furthermore, both of the flanges to be welded are provided with internal threaded holes at the ends away from the sensor body, and the internal threaded holes communicate with the second inner hole. The first connector and the second connector are respectively provided with external threads that mate with the internal threaded holes.

[0012] Furthermore, the upper part of the fixed bracket is provided with a stepped first positioning hole, and a first positioning plate is installed in the first positioning hole through a bearing; one end of the first positioning plate passes through the first positioning hole and is connected to the handwheel, and the other end is axially provided with a positioning groove for positioning the first connecting piece. The first positioning plate corresponds to the shape of the first positioning hole, and the diameter increases sequentially from the handwheel end to the connector end.

[0013] Furthermore, the upper part of the movable bracket is provided with a stepped second positioning hole, and a second positioning plate is installed in the second positioning hole through a bearing; one end of the second positioning plate is located in the second positioning hole, and the other end is axially provided with a positioning groove for positioning the second connecting piece.

[0014] Furthermore, the piston rod at the telescopic end of the clamping device contacts the end face of the second connector through the second positioning hole, and the contact end of the piston rod is a spherical contact head.

[0015] Furthermore, the base is provided with a guide rail for sliding the movable bracket, the bottom of the movable bracket is provided with a sliding groove for cooperating with the guide rail, and the side of the movable bracket is provided with a locking component.

[0016] A sealing welding method for a lubricating oil metal shavings sensor includes the following steps: S1. Place the tube inside the sensor body and insert both ends of the tube into the first inner holes of the two flanges to be welded. Connect the left flange to the first connector and the right flange to the second connector to form a sensor assembly. S2. Place the first connector and the second connector at both ends of the sensor assembly into the positioning slots of the first positioning plate and the second positioning plate, respectively, and axially lock the sensor assembly by adjusting the position of the movable bracket. S3. The clamping device applies axial clamping force to the second connecting piece, causing the through pipe to radially contract and form an interference fit with the second inner hole of the flange to be welded, thereby achieving axial sealing. S4. Fill the inlet of the detection channel of the second connector with 0.5MPa to 1MPa compressed air, and apply soapy water to the gap between the flange to be welded and the sensor body to be welded to observe the bubbles and determine whether the air tightness test is qualified. S5. After the airtightness test is passed, the clamping device maintains the clamping force in S3 and uses welding equipment to spot weld the gap to be welded; after spot welding is completed, the clamping device is depressurized to 30% to 50% of the original clamping force, and the gap to be welded is welded around the entire circle. S6. After welding is completed, remove the sensor assembly and perform an airtightness test on the welded sensor to determine whether the sensor's sealing performance is qualified.

[0017] In S3, pressurization stops when the clamping force reaches 2.5kN, and the two ends of the pipe form an interference fit with the second inner hole of the two flanges to be welded.

[0018] Compared with the prior art, the sealing welding fixture and method for the lubricating oil metal shavings sensor described in this invention have the following advantages: (1) The first connector of the sealing welding fixture described in this invention adopts a solid structure, while the second connector has an internal detection channel. Through the differentiated design of the first and second connectors, a fully sealed airtightness test of the sensor is achieved before welding. By conducting pre-welding airtightness testing, quality control is achieved in advance, fundamentally avoiding rework or scrapping caused by discovering oil leakage after welding, and significantly reducing scrap rate and manufacturing costs. In the batch production verification of 100 samples, the first-pass yield increased from 92% in the traditional process to 98%, and the scrap rate decreased from 8% to 2%, a reduction of 75%, resulting in significant cost savings.

[0019] (2) The integrated design of the sealing welding fixture described in this invention integrates sealing detection, positioning, clamping, and welding support functions into one unit, realizing the completion of all processes in a single clamping, which greatly improves production efficiency and operational efficiency. In the production statistics of the same batch (25 samples), the traditional process takes 3.2 hours to complete 25 samples, while the welding method of this invention takes 2.5 hours to complete 25 samples. The processing time per piece is shortened by 25%, and the production cycle is increased from 8 pieces / hour of the traditional process to 10 pieces / hour of the welding process. At the same time, the number of fixtures is reduced, which reduces procurement costs, storage space requirements, and maintenance workload.

[0020] (3) This invention achieves reliable sealing of metal-PEEK dissimilar materials through a dual sealing mechanism of "radial sealing + axial sealing" combined with a clamping device, and performs sealing verification before welding to ensure that only sensors with qualified sealing can enter the welding process. Specifically: A sealing ring is installed at both ends of the pipe where it mates with the inner hole of the flange to be welded. A reliable radial seal is formed by the radial compression deformation of the sealing ring in the sealing groove of the inner hole of the flange to be welded. Axial sealing is achieved by utilizing the excellent elastic modulus (3.6 GPa) and elastic recovery properties of PEEK material. When an axial clamping force of 2.5 kN is applied by the clamping device, the PEEK pipe undergoes elastic deformation, with a slight reduction in its outer diameter, allowing it to insert into the inner bore of the flange to be welded, forming an interference fit. Under clamping conditions, the PEEK pipe is tightly fitted against the flange inner bore, and the elastic recovery force of the PEEK material continuously acts on the mating surfaces, forming a reliable axial seal. This sealing mechanism is highly reliable, with a leakage rate significantly lower than traditional single sealing methods. It is also highly adaptable, durable, and greatly improves the sealing performance and reliability of the product.

[0021] (4) The present invention achieves high-precision positioning of various components of the sensor during the welding process through the cooperation of the first positioning card, the second positioning card, the movable bracket and the guide rail. The uniformity of the weld gap is significantly improved, the consistency of welding parameters is enhanced, the rework rate is greatly reduced, and the process capability index Cpk is increased from 1.1 to 1.5.

[0022] The adjustable and adaptable design of the movable bracket allows it to cover sensor products of different lengths, reducing tooling investment, shortening new product development cycles, and reducing inventory, which is in line with the lean manufacturing concept.

[0023] (5) The present invention adopts a segmented welding process of “spot welding positioning + micro pressure relief + full circle welding”, which cleverly solves the contradiction between welding positioning accuracy and workpiece rotatability, reduces welding stress and deformation, improves weld quality, is easy to operate, adapts to a variety of welding equipment, and has strong application flexibility.

[0024] The slightly compressed state after micro-depressurization significantly reduced welding stress and deformation, with welding residual stress decreasing from 180 MPa to 70 MPa. The roundness and flatness of the welded parts improved by 47% and 50%, respectively. At the same time, the reduction in welding stress reduced the tendency for hot cracking, and rotary welding ensured the consistency of welding parameters.

[0025] (6) This invention provides a special welding fixture for welding lubricating oil metal shavings sensors. Its specialized design precisely matches the structural features and material combination of the sensor. The process parameters have been optimized, the process is mature and reliable, the product qualification rate is high, and it has strong market competitiveness. In addition, its core technology has broad applicability and can be applied to other types of sensors, tubular component welding, dissimilar material combination components, and products with high sealing requirements, etc., with broad market application prospects. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of the present invention; Figure 2 This is a cross-sectional view of the overall structure provided in an embodiment of the present invention; Figure 3 for Figure 2 Enlarged view of part A in the middle; Figure 4 This is a schematic diagram of a flange structure provided in an embodiment of the present invention; Figure 5 A schematic cross-sectional view of a flange provided for an embodiment of the present invention. Figure 6This is a schematic diagram of the pipe structure provided in an embodiment of the present invention; Figure 7 A cross-sectional view of the conduit provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the first connector structure provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the second connector structure provided in an embodiment of the present invention; Figure 10 This is a cross-sectional schematic diagram of the second connector provided in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Base; 2. Fixed bracket; 21. First positioning hole; 22. First positioning plate; 3. Movable bracket; 31. Second positioning hole; 32. Second positioning plate; 4. Clamping bracket; 5. Sensor; 51. Sensor body; 52. Through pipe; 521. Protrusion; 522. Sealing ring; 53. Flange to be welded; 531. First inner hole; 532. Second inner hole; 6. First connecting piece; 7. Second connecting piece; 71. Detection channel; 8. Clamping device; 9. Handwheel; 10. Guide rail; 11. Handle; B. Interference fit between through pipe and flange to be welded. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] Example 1 like Figures 1 to 10 As shown, a sealing welding fixture for a lubricating oil metal shavings sensor includes a base 1. From left to right, a fixed bracket 2, a movable bracket 3, and a clamping bracket 4 are arranged on the upper surface of the base 1. The sensor 5 is clamped between the fixed bracket 2 and the movable bracket 3. The movable bracket 3 is slidably connected to the base 1. The sensor 5 includes a sensor body 51, a through pipe 52 disposed within the sensor body 51, and welding flanges 53 disposed on both sides of the sensor body 51; wherein, the left welding flange is connected to the first connecting member 6, and the end of the first connecting member 6 is placed on the fixed bracket 2; the right welding flange is connected to the second connecting member 7, and the end of the second connecting member 7 is placed on the movable bracket 3. The second connector 7 is provided with a detection channel 71. The inlet of the detection channel 71 is used to connect to the air pressure detection device, and the outlet of the detection channel 71 is connected to the inner cavity of the sensor 5 to perform air tightness detection on the sensor 5. The clamping bracket 4 is equipped with a clamping device 8, which is used to apply axial pressure to the second connecting piece 7, so that the flange 53 to be welded is axially clamped to the sensor body 51, and the two ends of the PEEK material pipe 52 are radially contracted and respectively embedded into the inner hole of the corresponding flange 53 to be welded to achieve an interference fit.

[0033] In this embodiment, sensor 5 is applied to the lubrication oil system of an aircraft engine. The sensor body 51 and the flange to be welded 53 are made of 316L stainless steel. The sensor body 51 contains the sensitive element and circuit of sensor 5. The outer diameter of the sensor body 51 is 13mm, the axial length is 140mm, the through pipe 52 is PEEK-1000, the working pressure is ≤2MPa, and the working temperature is -55℃~150℃.

[0034] This embodiment integrates the welding fixture and sealing detection function of the lubricating oil metal shavings sensor. Traditional welding fixtures can only provide positioning and clamping functions, while sealing detection needs to be performed on a separate detection device. The conversion between fixtures is not only time-consuming (15 to 20 minutes each time), but also introduces secondary positioning errors, affecting welding quality. Specifically: The first connector 6 adopts a solid sealing structure, which is completely sealed and forms a sealed end after being connected with the flange to be tested; the second connector 7 adopts a hollow structure and has a detection channel 71 inside. The detection channel 71 includes a connected axial channel (diameter 8mm) and a radial pressure channel. The axial channel is connected to the inner cavity of the sensor 5 after the sensor body 51, the flange to be welded 53 and the through pipe 52 are assembled. The radial pressure channel is machined with internal threads (M6×1 thread) and can be directly connected to the air pressure detection equipment.

[0035] The working principle is as follows: Compressed air at 0.5MPa to 1.0MPa is injected into the inner cavity of sensor 5 through the radial pressurization channel. Since one end of the inner cavity of sensor 5 is completely sealed with the first connecting piece 6, and the other end is sealed with the second connecting piece 7 through the O-ring 522, the compressed air is completely sealed inside the inner cavity of sensor 5. At this time, soapy water or bubble water is applied to the external mating surface (welding position) of sensor body 51 and flange 53, and observed for 2 to 5 minutes. If bubbles are generated at this point, it indicates a defect in the internal sealing system of sensor 5 (poor fit between pipe 52 and flange, improper installation of O-ring, etc.); if no bubbles are generated and the pressure drop is less than or equal to 0.02MPa, it indicates that the sealing system is qualified and the welding process can proceed.

[0036] The pre-welding sealing inspection function enables pre-welding quality control, allowing for timely detection of assembly defects before welding and effectively avoiding rework or scrap caused by post-welding oil leakage. Secondly, the integrated design eliminates the tooling conversion process, significantly improving production efficiency by more than 25%. Finally, it ensures precise and consistent positioning, eliminates secondary positioning errors, and further improves welding quality.

[0037] In a preferred embodiment of the present invention, each of the two flanges to be welded 53 near the sensor body 51 is provided with a first inner hole 531 and a second inner hole 532 connected in sequence, wherein the diameter of the first inner hole 531 is larger than the diameter of the second inner hole 532; both ends of the through pipe 52 are respectively provided with protrusions 521 that cooperate with the first inner hole 531, the end of the through pipe 52 is used to be embedded in the second inner hole 532, and the outer diameter of the end of the through pipe 52 is larger than the diameter of the second inner hole 532.

[0038] The side wall of the first inner hole 531 is provided with a sealing groove for installing the sealing ring 522.

[0039] The outer diameter of the end of the through pipe 52 ranges from 10.00 mm to 10.03 mm, and the diameter of the second inner hole 532 of the flange to be welded is 9.92 mm.

[0040] Specifically, PEEK and metals are dissimilar materials, and their coefficients of thermal expansion differ significantly (PEEK is approximately 5.10). -6 / K, while stainless steel is approximately 1.7·10 -5 Traditional sealing solutions (such as simple O-ring seals or adhesive seals) are either unreliable or overly complex. This invention fully utilizes the excellent elastic properties of PEEK material to design a dual sealing mechanism of "radial sealing + axial sealing," and achieves this sealing effect through the clamping function of tooling.

[0041] Radial sealing: A sealing groove is opened on the side wall where the first inner hole 531 mates with the through pipe 52. An O-ring 522 (specification φ15·2.65, material is fluororubber FKM, hardness 70±5 Shore A) is installed in the sealing groove. Radial sealing is achieved by the radial compression deformation of the sealing ring 522 (compression rate 15%~25%) to prevent lubricating oil from leaking from the radial gap.

[0042] Axial sealing: The outer diameter of the through pipe 52 is 10.00mm to 10.03mm, while the diameter of the second inner hole 532 of the flange to be welded is 9.92mm (tolerance H7), resulting in an interference fit of 0.08mm to 0.12mm. Under normal temperature and free conditions, the through pipe 52 cannot be inserted into the flange inner hole.

[0043] When the clamping device 8 applies an axial clamping force of 2.5kN, due to the excellent elastic modulus (3.6GPa, between rigid plastics and flexible rubber) and elastic recovery performance of PEEK, the PEEK tube 52 undergoes elastic deformation under axial pressure, and the outer diameter shrinks slightly by about 0.1mm (equivalent to 3% radial elastic deformation), allowing the tube 52 to be inserted into the flange inner hole.

[0044] Under compressed conditions, the outer diameter of the PEEK pipe 52 fits tightly against the second inner hole 532 of the metal flange, forming an interference fit. Because the elastic restoring force of the PEEK material continuously acts on the mating surfaces, it generates continuous contact pressure (active sealing), maintaining the sealing contact force even under dynamic conditions such as vibration and thermal cycling, ensuring no air leakage within the sensor 5 cavity. Testing has shown that the leakage rate of this dual-sealing mechanism is less than or equal to 1.10. -3 Pa·m3 / s, compared to traditional single sealing methods (leakage rate less than or equal to 5.10 Pa·m3 / s), -3 The pressure (Pa·m3 / s) has been increased by 80%, reaching the high vacuum sealing standard.

[0045] Once the dual sealing mechanism is established, the entire sealing system (radial seal + axial seal) can be verified before welding using differentiated flange connections in the tooling. This pre-weld verification is crucial for resolving the sealing issues of dissimilar materials—it not only verifies the installation quality of the sealing elements (O-rings), but more importantly, it verifies the reliability of the interference fit between the PEEK pipe 52 and the metal flange. Only when both sealing mechanisms are qualified can the sensor 5 pass the airtightness test and proceed to the welding process. This combination of "radial seal + axial seal" ensures the reliability of the seal from a fundamental mechanism perspective.

[0046] Advantages of the double sealing mechanism: First, no additional sealing elements are required. Compared to adhesive sealing solutions, there is no curing time, resulting in higher production efficiency; compared to the multi-layer sealing ring 522 solution, there are fewer parts (fewer BOM items), assembly is simpler, and the cost is reduced by approximately 15 yuan per piece.

[0047] Second, it is highly adaptable. By adjusting the clamping force, it can adapt to the performance differences of different batches of PEEK materials (elastic modulus fluctuation range ±10%), as well as the size requirements of different sensor specifications 5, with a wide process window.

[0048] Third, it exhibits excellent durability. PEEK material possesses excellent chemical stability (resistant to almost all organic solvents and oils), high-temperature resistance (long-term operating temperature 260℃), and fatigue resistance (flexural fatigue strength >107 cycles). A 1000-hour accelerated aging test (150℃ + 2MPa + 20g vibration) showed no degradation in sealing performance, ensuring the long-term reliability of sensor 5.

[0049] In a preferred embodiment of the present invention, both of the flanges 53 to be welded are provided with internal threaded holes at the ends away from the sensor body 51, and the internal threaded holes communicate with the second inner hole 532. The first connecting member 6 and the second connecting member 7 are respectively provided with external threads that cooperate with the internal threaded holes.

[0050] Specifically, both the first connector 6 and the second connector 7 are equipped with O-rings 522 at their mating points with the internal threaded holes. The O-rings 522 are made of fluororubber, with a specification of φ15·2.65, a temperature resistance range of -40℃ to 200℃, and excellent oil resistance, ensuring axial sealing at the connection. The solid structure of the first connector 6 ensures that one end of the sealing system is completely sealed, providing a reliable sealing end for pre-welding airtightness testing. The external thread specification of the first connector 6 is a pipe thread G1 / 4.

[0051] The external thread on the second connector 7 is threaded to the flange 53 to be welded, and the thread specification is pipe thread G1 / 4.

[0052] In a preferred embodiment of the present invention, the upper part of the fixed bracket 2 is provided with a stepped first positioning hole 21, and a first positioning plate 22 is installed in the first positioning hole 21 by means of a bearing. One end of the first positioning plate 22 passes through the first positioning hole 21 and is connected to the handwheel 9. The other end of the first positioning plate 22 is provided with a positioning groove for positioning the first connecting piece 6 axially. The first positioning plate 22 corresponds to the shape of the first positioning hole 21, and the diameter increases sequentially from the handwheel 9 end to the connector end.

[0053] Specifically, the first positioning plate 22 has a chamfer between the two steps inside the first positioning hole 21, and the step in the middle is installed in the first positioning hole 21 through a bearing; the first positioning plate 22 is close to the end of the first connector 6, and the vertical part of the step outside the first positioning hole 21 is in contact with the end face of the bearing, so as to accurately position the first connector 6 and the sensor assembly in the radial and axial directions with a positioning accuracy of 0.02mm.

[0054] The height of the fixed bracket 2 is 90mm, and it is fixed to the base 1 with bolts. The fixed bracket 2 is made of 40Cr alloy steel and is hardened to HRC45~50, which ensures sufficient strength and rigidity.

[0055] In a preferred embodiment of the present invention, the upper part of the movable bracket 3 is provided with a stepped second positioning hole 31, and a second positioning plate 32 is installed in the second positioning hole 31 by means of a bearing; the second positioning plate 32 is stepped, one end of the second positioning plate 32 is located in the second positioning hole 31, and the other end is provided with a positioning groove for positioning the second connecting member 7.

[0056] Specifically, a second connector 7 is installed in the positioning groove for radial and axial fixing of the sensor 5.

[0057] In a preferred embodiment of the present invention, the piston rod at the telescopic end of the pressing device 8 contacts the end face of the second connector 7 through the second positioning hole 31, and the contact end of the piston rod is a spherical contact head.

[0058] Specifically, the clamping device 8 employs a detachable jack (hydraulic or pneumatic), and the clamping bracket is fixedly connected to the base with screws. The piston rod of the detachable jack points towards the bracket, and the end of the piston rod is equipped with a spherical contact head, which contacts the end face of the second connecting piece 7 through the second positioning hole 31. The clamping device 8 can provide an axial clamping force of 0kN to 5kN. The clamping force is adjusted by the adjusting component of the detachable jack, and a pressure gauge is provided to display the current pressure value in real time.

[0059] The clamping device 8 can perform precise pressure adjustment and micro-pressure relief. During the airtightness testing and spot welding positioning stages, a larger clamping force (2.5kN) is applied to ensure a tight fit between the PEEK pipe 52 and the flange inner hole. During the full-circle welding stage, the clamping force can be reduced to about 1.0kN (30% to 50% of the initial pressure) through micro-pressure relief, so that the sensor assembly is in the optimal state of being neither loose nor rotatable, supporting the workpiece rotation for 360° full-circle welding.

[0060] In a preferred embodiment of the present invention, the base 1 is provided with a guide rail 10 for sliding the movable bracket 3, the bottom of the movable bracket 3 is provided with a sliding groove for cooperating with the guide rail 10, and the side of the movable bracket 3 is provided with a locking component.

[0061] Specifically, base 1 serves as the reference platform for the entire tooling, providing a stable installation reference for each functional module. Base 1 is made of 20mm thick No. 45 steel plate (material code: GB / T 699-2015), with dimensions of 800mm × 300mm, capable of accommodating the processing requirements of sensors 5 of different specifications. The surface is precision ground, with a flatness ≤0.02mm. The processing steps of base 1 are: ① blanking (laser cutting or waterjet cutting); ② rough machining (milling six sides); ③ stress-relief annealing (600℃ × 2h, furnace cooling); ④ finish machining (precision grinding of the upper surface); ⑤ quality inspection.

[0062] At least one guide rail 10 mounting groove is machined on the upper surface of the base 1. In this embodiment, two guide rail 10 mounting grooves are machined for mounting linear guide rails 10. The mounting grooves are T-slots, 24mm wide, 0.5mm deep, and 400mm apart. The linear guide rails 10 have an accuracy class of H and a parallelism of less than or equal to 0.02mm / m to ensure the sliding accuracy of the movable bracket 3. The movable bracket 3 is slidably mounted on the base 1 via the guide rails 10, with an adjustment range of 100mm, which can accommodate sensors 5 of different lengths. The bottom of the movable bracket 3 is connected to the guide rails 10 by ball bearings, resulting in a low coefficient of friction and smooth movement. M6 threaded holes are provided at the four corners of the bottom of the base 1 for use with support feet (height adjustable ±30mm) to facilitate horizontal adjustment and fixation on the workbench.

[0063] The locking component is a locking handle, which is threaded to the side of the movable bracket 3 and passes through the side of the movable bracket 3 to abut against the guide rail 10. The locking handle can lock the movable bracket 3 onto the guide rail 10 to prevent displacement during the airtightness test and welding process, and ensure the stability of the positioning accuracy.

[0064] Example 2 A sealing welding method for a lubricating oil metal shavings sensor 5 includes the following steps: S1. Place the through pipe 52 inside the sensor body 51, and insert both ends of the through pipe 52 into the first inner holes 531 of the two flanges to be welded, respectively. The left flange to be welded is connected to the first connecting piece 6, and the right flange to be welded is connected to the second connecting piece 7 to form a sensor assembly. S2. Place the first connector 6 and the second connector 7 at both ends of the sensor assembly into the positioning slots of the first positioning plate 22 and the second positioning plate 32 respectively, and axially lock the sensor assembly by adjusting the position of the movable bracket 3. S3. The clamping device 8 applies an axial clamping force to the second connecting piece 7, causing the through pipe 52 to radially contract and form an interference fit with the second inner hole 532 of the flange to be welded, thereby achieving an axial seal. S4. Inject 0.5MPa to 1MPa compressed air into the inlet of the detection channel 71 of the second connector 7, and apply soapy water to the gap between the flange 53 to be welded and the sensor body 51 to be welded and observe the bubbles to determine whether the air tightness test is qualified. S5. After the airtightness test is passed, the clamping device 8 maintains the clamping force in S3 and uses welding equipment to spot weld the gap to be welded; after spot welding is completed, the clamping device 8 is depressurized to 30% to 50% of the original clamping force, and the entire gap to be welded is welded. S6. After welding is completed, remove the sensor assembly and perform an airtightness test on the welded sensor 5 to determine whether the sealing performance of sensor 5 is qualified.

[0065] The sealing welding method for the lubricating oil metal shavings sensor 5 provided in this embodiment is specifically implemented as follows: Step 1: Assembly Preparation Install an O-ring 522 in the sealing groove of the flange 53 to be welded, and apply a small amount of lubricant evenly to the surface of the O-ring 522 to facilitate assembly and improve sealing performance. Assemble the sensor body 51, the two flanges 53 to be welded, and the through pipe 52, ensuring that both ends of the through pipe 52 are aligned with the first inner hole 531 of the flange 53 to be welded. Next, precisely align the internal threaded hole of the flange 53 to be welded with the external threads of the first connector 6 and the second connector 7, first manually tighten, and then use a torque wrench to tighten to a torque of 8 N·m to ensure a firm connection and good sealing effect. At the same time, install O-rings 522 at both ends of the through pipe 52, and carefully check to ensure that the O-rings 522 are not twisted or damaged.

[0066] Step 2: Sensor Positioning Adjust the position of the movable bracket 3 to ensure sufficient space for assembling the sensor 5. Secure the sensor assembly, consisting of the sensor body 51, two flanges 53 (already connected to the first connector 6 and the second connector 7 respectively), and the through pipe 52, between the first positioning bracket 22 and the second positioning bracket 32. The specific operating steps are as follows: First, insert the first connector 6 into the cylindrical positioning groove of the first positioning plate 22, ensuring that it is in close contact with the bottom wall of the positioning groove; then, adjust the position of the movable bracket 3 so that the positioning groove of the second positioning plate 32 is aligned with the sensor assembly, and put it on the second connector 7.

[0067] Precise radial positioning (positioning accuracy of 0.02mm) and axial positioning of the sensor assembly are achieved through the positioning slots on the first positioning plate 22 and the second positioning plate 32. After adjustment, tighten the locking components to lock the movable bracket 3 in its current position to prevent displacement during subsequent processes.

[0068] Step 3: Apply clamping force The clamping device 8 uses a jack. By manually adjusting the clamping device 8, the piston rod of the jack extends, and an axial clamping force is applied to the sensor assembly through the second connecting piece 7. As the clamping force gradually increases, the through pipe 52 undergoes elastic deformation under pressure, its outer diameter slightly shrinks, and it gradually inserts into the second inner hole 532 of the flange to be welded, forming an interference fit with the second inner hole 532 (interference fit point). Figure 3 (As shown in Figure B). Closely observe the pressure gauge. When the clamping force reaches 2.5kN, stop pressurizing. At this time, the through pipe 52 and the second inner hole 532 of the two flanges to be welded form a reliable interference fit, achieving axial sealing; at the same time, the gap between the sensor body 51 and the flanges to be welded 53 is effectively compressed, and the gap is uniform (deviation ≤0.03mm), creating good conditions for subsequent welding operations.

[0069] Step 4: Air tightness test Connect a pressure testing device, such as an airtightness tester, through the inlet of the detection channel 71 of the second connector 7. The airtightness tester is connected to the inlet of the detection channel 71 via a standard air pressure connector (M8×1.25 thread). Start the airtightness tester and fill the internal cavity of the sensor assembly with compressed air at a pressure ranging from 0.5 MPa to 1.0 MPa (preferably 0.8 MPa). During the inflation process, close the exhaust valve of the airtightness tester to ensure that the internal cavity of the sensor assembly maintains a constant pressure.

[0070] Apply a thin layer of soapy water or special bubble solution to the outer mating surface (i.e., the welding location) between the sensor body 51 and the flange 53 to be welded, and observe whether bubbles are generated at that location. The observation time is 2 to 5 minutes (preferably 3 minutes). At the same time, monitor the pressure gauge of the airtightness tester and record the pressure drop.

[0071] The judgment criteria are as follows: If no bubbles are generated at the gap within the observation time and the pressure drop does not exceed 0.02 MPa, the airtightness test is deemed qualified, and subsequent welding operations can proceed; if bubbles appear or the pressure drop exceeds the standard, the airtightness test is deemed unqualified. In this case, the pressure needs to be released, the sensor assembly needs to be removed, and the fit between the through pipe 52 and the flange 53 to be welded and the installation of the O-ring 522 need to be checked. The root cause of the problem needs to be identified, and the airtightness test needs to be performed again after reassembly or replacement of parts until the test is qualified.

[0072] The airtightness test is a key point in the quality control of the process of this invention. This step ensures that only the sensor 5 that is sealed properly can enter the welding process, thus fundamentally avoiding the problem of oil leakage after welding.

[0073] Based on the traditional threaded sealing ring process and the welding method of this embodiment, 100 samples were produced (divided into 4 batches of 25 pieces each). Statistical analysis showed that: Traditional threaded sealing ring process: First batch: 22 pieces qualified, 3 pieces unqualified, qualification rate 88%; Second batch: 23 pieces qualified, 2 pieces unqualified, qualification rate 92%; Third batch: 25 pieces qualified, 0 pieces unqualified, qualification rate 100%; Fourth batch: 22 pieces qualified, 3 pieces unqualified, qualification rate 88%. The overall qualification rate for the four batches is 92%, and the overall failure rate is 8%.

[0074] The welding method in this embodiment is as follows: The first batch had 25 qualified pieces and 0 unqualified pieces, with a pass rate of 100%; the second batch had 24 qualified pieces and 1 unqualified piece, with a pass rate of 96%; the third batch had 24 qualified pieces and 1 unqualified piece, with a pass rate of 96%; the fourth batch had 25 qualified pieces and 0 unqualified pieces, with a pass rate of 100%. The total pass rate for the four batches was 98%, and the total failure rate was 2%.

[0075] After mass production verification, compared with the traditional threaded sealing ring process, the welding method of this embodiment increased the first-pass yield from 92% to 98% and reduced the scrap rate from 8% to 2%, a reduction of 75%. Based on a material cost of 100 yuan and a processing cost of 50 yuan per sensor, with an annual production scale of 1000 units, scrap losses decreased from 120,000 yuan to 30,000 yuan, resulting in annual cost savings of 90,000 yuan. Simultaneously, it reduced rework time (each rework requires 3 hours) and quality disputes, resulting in significant overall economic benefits.

[0076] Step 5: Spot welding positioning After the airtightness test is passed, the pressure of the clamping device 8 is kept constant at 2.5kN, and spot welding is performed on the external mating surface of the sensor body 51 and the flange 53 to be welded using laser welding equipment. Spot welding is performed using pulsed laser welding, with the laser power set to 200W, the pulse width to 5ms, and the single-point welding time to 0.5 seconds. The spot welding positions are evenly distributed along the circumference, with a total of 5 to 6 welding points (the specific number depends on the diameter of the sensor body 51: 5 positions for a diameter less than or equal to 20mm, and 6 positions for a diameter greater than 20mm). The angle between any two adjacent spot welding positions is between 60° and 72°.

[0077] During spot welding, a laser beam is perpendicularly irradiated onto the gap between the sensor body 51 and the flange 53 to be welded, melting the contact edges to form a weld point. The depth of the spot weld is controlled between 0.5mm and 0.8mm, and the diameter of the weld point is within the range of 1.5mm to 2.0mm. After spot welding, the weld quality must be carefully inspected to ensure that there are no defects such as pores or cracks, and that the weld point is full and rounded. The main purpose of spot welding is to temporarily fix the sensor body 51 and the flange 53 to be welded, preventing them from separating or misaligning during subsequent micro-pressure relief and full-circle welding, thus providing a reliable positioning reference for the full-circle welding.

[0078] Step Six: Micro-pressure relief treatment After spot welding, the clamping device 8 needs to be slightly depressurized. At this time, the piston rod of the jack will retract a certain distance, and the clamping force will gradually decrease from 2.5kN to 1.0kN, that is, to 30%–50% of the original clamping force (precisely monitored by a pressure gauge). The main purpose of this slight depressurization is to reduce the axial pressure on the sensor assembly, so that the sensor assembly can be rotated manually or by motor during the entire welding process, thereby facilitating the movement of the laser welding head and multi-angle welding. The optimal slight depressurization ratio is determined to be 30%–50% based on the flatness, roundness, and sealing tests of the welded sample.

[0079] After slight depressurization, the operator should be able to smoothly rotate the sensor assembly manually (via handwheel 9 or by directly rotating the workpiece). The rotation torque should be controlled within the range of 3 N·m to 8 N·m to ensure that the operation is neither laborious nor too loose. Simultaneously, maintaining a clamping force of approximately 1.0 kN ensures tight contact and positioning accuracy between the main body and the flange components (radial offset ≤ 0.05 mm), preventing excessive gaps or misalignment during welding. The connection strength provided by the spot welds ensures that the components will not separate during welding.

[0080] Five sensor samples were randomly selected from both the conventional process and the welding method of this embodiment, and their roundness and flatness were tested respectively. The specific data are as follows: Traditional craftsmanship: The roundness values ​​were 0.15mm, 0.16mm, 0.12mm, 0.09mm, and 0.08mm, with an average of 0.12mm. The flatness values ​​were 0.07mm, 0.05mm, 0.06mm, 0.05mm, and 0.06mm, with an average of 0.058mm.

[0081] The welding method in this embodiment: The roundness values ​​were 0.09mm, 0.04mm, 0.06mm, 0.07mm, and 0.06mm, with an average of 0.064mm. The flatness values ​​were 0.02mm, 0.02mm, 0.03mm, 0.04mm, and 0.04mm, with an average of 0.029mm.

[0082] The comparison shows that the average roundness after welding increased from 0.12 mm to 0.064 mm, an improvement of about 47%; the average flatness increased from 0.058 mm to 0.029 mm, an improvement of about 50%. At the same time, the stress release during micro-pressure relief decreased by 60%, and the welding residual stress decreased from 180 MPa to 70 MPa, a reduction of 61%.

[0083] This embodiment achieves high-precision positioning of sensor components during the welding process, significantly improves weld gap uniformity, enhances welding parameter consistency, greatly reduces rework rate, and increases process capability index Cpk from 1.1 to 1.5.

[0084] The process capability index is calculated using the formula: Cpk=min((USL-μ) / 3σ,(μ-LSL) / 3σ).

[0085] USL represents the upper limit of flatness specification, USL=0.065mm; LSL represents the lower limit of flatness specification, LSL=0; Using five sensors to measure flatness, the average μ value of samples from traditional processes is 0.058 mm, while the μ value of the welding process of this invention is 0.029 mm. The standard deviation of the traditional process is σ=0.0021mm, while the standard deviation of the welding process of this invention is σ=0.0064mm.

[0086] calculate: When u = 0.058 mm, the traditional process CPK = 1.1; When u=0.029mm, the welding process of this invention has a CPK=1.5.

[0087] Step 7: Weld the entire circle Laser welding equipment is used for full-circle welding. Two methods can be used during welding: Method 1 (Workpiece Rotation): The operator manually rotates handwheel 9 or directly rotates the sensor assembly, or starts the motor to automatically drive the workpiece to rotate. The laser welding head is fixed in a suitable position, aligned with the outer mating surface (circumferential weld) of the main body and the flange component. The rotation speed of the sensor assembly should match the laser welding speed. For example, if the welding speed is 8 mm / s and the circumference length of the sensor body 51 is approximately 60 mm (φ19 mm), then the rotation speed is approximately 0.13 revolutions / second (approximately 8 rpm).

[0088] Method 2 (Welding Head Rotation): If a welding robot or welding turntable is used, the sensor assembly can be fixed, and the laser welding head can move circumferentially for welding. This method is also supported in the micro-depressurization state of the tooling in this embodiment.

[0089] The entire circumference is welded using continuous laser welding with a laser power of 250W, a welding speed of 8mm / s, a welding depth of 1.0mm–1.5mm, and a weld width of 1.5mm–2.0mm. During welding, a shielding gas (argon, purity ≥99.99%, flow rate 15L / min) is used to protect the welding area and prevent oxidation. To ensure welding quality, the welding speed, laser power, and shielding gas flow rate should be maintained uniformly throughout the entire welding process. Operators should closely monitor the condition of the weld pool and adjust parameters promptly.

[0090] After welding, the weld should be continuous, uniform, and smooth, without obvious defects such as depressions, protrusions, or porosity. The weld should transition smoothly with the base material, without obvious undercut. After the entire circumference is welded, a strong and permanent connection is formed between the main body and the flange components.

[0091] The offset of five sensor samples after full-circle welding using the welding method of this invention was measured, and the results are as follows: The radial offsets are 0.04mm, 0.03mm, 0.04mm, 0.03mm, and 0.05mm, respectively, with a maximum value ≤ 0.05mm; The axial offsets (i.e., coaxiality) are 0.01mm, 0.02mm, 0.015mm, 0.02mm, and 0.01mm, respectively, with a maximum value of ≤0.02mm.

[0092] The above data shows that the radial offset is ≤0.05mm and the coaxiality is ≤0.02mm during the entire welding process, which meets the requirements of high-precision welding.

[0093] Step 8: Post-weld treatment After the entire circle of welding is completed, release the pressure of the clamping device 8, and the jack piston rod will fully retract, reducing the clamping force to zero. Loosen the locking device, move the movable block away, and remove the sensor 5 from the fixture. At this point, the body of the sensor 5 and the flange 53 to be welded have formed an integrated structure through welding.

[0094] Use sandpaper or a grinder to grind the weld seam, removing surface defects such as welding spatter and oxides, making the weld surface smooth and flat. Be careful not to over-grind during grinding to avoid damaging the weld. After grinding, carefully inspect the weld quality using a magnifying glass or microscope, checking for the following defects: incomplete welds (partially unwelded areas), missing welds (discontinuous weld seams), insufficient weld depth or width, porosity (holes inside or on the surface of the weld), cracks (cracks in the weld or heat-affected zone), and undercut (grooves forming at the weld edge).

[0095] If the above defects are found, the defective locations need to be repaired by welding. During repair welding, remount sensor 5 onto the fixture (no clamping force is required, as the body and flange are already welded together), and use laser welding equipment to locally weld the defective location until the defect is repaired. The laser power can be appropriately increased (e.g., 280W) to ensure complete penetration. After repair welding, grind and inspect again until the weld quality is acceptable.

[0096] Finally, a final airtightness test is performed on the welded sensor 5 to verify the welding quality and sealing performance. One end of sensor 5 is sealed with a plug, and the other end is connected to an airtightness tester. Compressed air at 1.0 MPa is introduced and held at that pressure for 5 minutes, and the pressure drop is observed. If the pressure drop is less than or equal to 0.01 MPa, sensor 5 is considered to have qualified sealing performance and can be put into storage or proceed to the next process; if the pressure drop exceeds the limit, sensor 5 is considered unqualified, and the cause needs to be analyzed (whether there are minor defects in the weld) and it needs to be reworked or scrapped.

[0097] Laser welding of sensor 5 requires uniform gap (deviation ≤0.05mm) and high coaxiality (≤0.02mm) between the main body and the flange, which necessitates a large clamping force. Simultaneously, sensor 5 has a circumferentially symmetrical structure, requiring 360° rotation for full-circumference welding, which in turn demands free workpiece rotation. This presents a seemingly contradictory requirement: rigid clamping offers high positioning accuracy but prevents rotation, while loose clamping allows rotation but results in poor positioning accuracy. To address this need, the sealing welding method for the lubricating oil metal shavings sensor 5 provided in this embodiment employs a "segmented clamping + micro-pressure relief" process during welding. This process consists of three stages, specifically: 1) Phase 1: Air tightness test and electric welding (maximum compression 2.5kN) In the fourth step of the airtightness test, a large clamping force (2.5kN) is applied to ensure that the PEEK pipe 52 and the flange 53 to be welded form a tight fit and achieve a seal. On the other hand, it ensures that the sensor body 51 and the flange 53 to be welded are tightly fitted and the weld gap is uniform (deviation ≤0.03mm), providing a stable positioning reference for subsequent welding.

[0098] After the airtightness test is passed, in step five, the clamping force of 2.5kN is kept constant, and spot welding is performed on the outer joint surface (circumferential weld) of the sensor body 51 and the flange to be welded 53 using laser welding equipment.

[0099] The purpose of spot welding is to temporarily fix the body and flange, forming a sufficient connection strength (estimated tensile strength of about 500N), to prevent misalignment or separation during subsequent micro-pressure relief and full-circle welding. Although the spot welds are small, their reasonable distribution can effectively "lock" the relative positions of the body and flange.

[0100] 2) Phase Two: Micro-pressure relief treatment (reduced to 1.0kN) In step six, by slightly depressurizing, the sensor assembly is in an optimal state of being "neither loose nor misaligned." On the one hand, the spot welds provide sufficient connection strength to prevent component separation, and the guide rail 10 ensures radial positioning (radial offset ≤ 0.05 mm), so the sensor assembly will not loosen or become misaligned. On the other hand, the reduced clamping force significantly reduces the frictional resistance between the workpiece and the tooling, allowing the workpiece to rotate smoothly. The rotational torque is controlled within the range of 3 N·m to 8 N·m, allowing the operator to manually rotate the workpiece or achieve automatic rotation via a motor drive.

[0101] Controlling the pressure relief level is crucial to the process. Insufficient pressure relief (pressure greater than 1.5 kN) will prevent the workpiece from rotating; excessive pressure relief (pressure less than 0.5 kN) may cause the workpiece to loosen, leading to positioning errors. Extensive experimentation determined the optimal pressure relief ratio to be 30%–50% (i.e., reduced to approximately 1.0 kN), at which point the rotational torque is moderate and the positioning accuracy meets requirements.

[0102] 3) Phase Three: Full-circle welding (maintaining a slight compressive force of 1.0kN) After slight depressurization, the full-circle welding stage begins. In this embodiment, the tooling employs a workpiece rotation welding method: the operator manually rotates handwheel 9 or directly rotates the workpiece to make the sensor assembly rotate at a uniform speed. The laser welding head is fixed in a suitable position, aligned with the outer mating surface (circumferential weld) of the main body and the flange, and continuous laser welding is performed.

[0103] The entire circumference was welded using continuous laser welding with a laser power of 250W, a welding speed of 8mm / s, a welding depth of 1.0mm to 1.5mm, and a weld width of 1.5mm to 2.0mm. The shielding gas was argon (purity ≥99.99%, flow rate 15L / min). After completing the 360° circumference welding, the weld was continuous and uniform, without obvious defects such as depressions, protrusions, or porosity.

[0104] 4) Summary This segmented clamping process achieves a balance between positioning accuracy and rotatability, perfectly resolving conflicting requirements. The high clamping pressure (2.5kN) during the spot welding stage ensures high positioning accuracy, while the light clamping pressure (1.0kN) after slight depressurization allows rotation. The spot welds provide sufficient strength to prevent misalignment. Actual measurement data shows that the radial offset is less than or equal to 0.05mm and the coaxiality is less than or equal to 0.02mm throughout the entire welding process, meeting the requirements for high-precision welding.

[0105] This segmented clamping process reduces welding stress and deformation. Compared to full-process full clamping (2.5kN), the light clamping state after slight depressurization (1.0kN) reduces the stress release during pressure release after welding by 60%, and the residual welding stress decreases from 180MPa to 70MPa, a reduction of 61%. Light clamping also allows for limited thermal expansion freedom of the workpiece, reducing thermal stress accumulation. The roundness after welding improves from 0.12mm to 0.064mm (an improvement of 47%), and the flatness improves from 0.058mm to 0.029mm (an improvement of 50%), resulting in significantly improved dimensional accuracy.

[0106] This segmented clamping process improves weld quality. The reduction in welding stress decreases the tendency for hot cracking, while rotary welding ensures consistency in welding parameters (significantly reducing the number of arc initiation and termination times compared to segmented fixed-position welding). The first-grade weld X-ray inspection rate increased from 85% to 96%, and the weld quality reached the international advanced level.

[0107] This segmented clamping process is adaptable to various welding equipment. The tooling supports both a simple method of manually rotating the workpiece with a fixed laser welding head (low investment cost, suitable for small-batch production) and an automated method of motor-driven rotation with a welding robot (high production efficiency, suitable for mass production), offering high application flexibility and lowering the barrier to entry.

[0108] The segmented clamping process is simple to operate. Depressurization is straightforward, requiring only adjustment of the jack clamping force, which can be monitored in real-time via a pressure gauge. Operators can master the process with minimal training. The overall segmented welding process only adds no more than 2 minutes to the operation time, but results in a significant improvement in quality and a high return on investment.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sealing welding fixture for a lubricating oil metal shavings sensor, characterized in that: The base includes a fixed bracket, a movable bracket, and a clamping bracket arranged sequentially from left to right on the upper surface of the base. The sensor is clamped between the fixed bracket and the movable bracket, and the movable bracket is slidably connected to the base. The sensor includes a sensor body, a through pipe disposed within the sensor body, and welding flanges disposed on both sides of the sensor body; wherein, the left welding flange is connected to a first connecting member, the end of the first connecting member being placed on a fixed bracket; the right welding flange is connected to a second connecting member, the end of the second connecting member being placed on a movable bracket; The second connector is provided with a detection channel. The inlet of the detection channel is used to connect to a barometric pressure testing device, and the outlet of the detection channel is connected to the inner cavity of the sensor to perform airtightness testing on the sensor. A clamping device is installed on the clamping bracket. The clamping device is used to apply axial pressure to the second connecting piece, so that the flange to be welded is axially clamped to the sensor body, and the two ends of the PEEK material pipe are radially contracted and respectively embedded into the inner hole of the corresponding flange to be welded to achieve an interference fit.

2. The sealing welding fixture for the lubricating oil metal shavings sensor according to claim 1, characterized in that: Both flanges to be welded are provided with a first inner hole and a second inner hole connected in sequence near the sensor body, wherein the diameter of the first inner hole is larger than the diameter of the second inner hole; both ends of the through pipe are provided with protrusions that cooperate with the first inner hole, the end of the through pipe is used to be embedded in the second inner hole, and the outer diameter of the end of the through pipe is larger than the diameter of the second inner hole.

3. The sealing welding fixture for the lubricating oil metal shavings sensor according to claim 2, characterized in that: Both of the flanges to be welded have a sealing groove on the first inner hole sidewall for installing a sealing ring, and a sealing ring is provided at the connection between the two flanges to be welded and the first and second connecting parts.

4. The sealing welding fixture for the lubricating oil metal shavings sensor according to claim 2, characterized in that: The outer diameter of the end of the pipe is in the range of 10.00mm to 10.03mm, and the second inner diameter of the flange to be welded is 9.92mm.

5. The sealing welding fixture for the lubricating oil metal shavings sensor according to claim 2, characterized in that: Both flanges to be welded have internal threaded holes at the ends away from the sensor body, and the internal threaded holes communicate with the second inner hole. The first connector and the second connector are respectively provided with external threads that mate with the internal threaded holes.

6. The sealing welding fixture for the lubricating oil metal shavings sensor according to claim 1, characterized in that: The upper part of the fixed bracket is provided with a stepped first positioning hole, and a first positioning plate is installed in the first positioning hole through a bearing; one end of the first positioning plate passes through the first positioning hole and is connected to the handwheel, and the other end is provided with a positioning groove for positioning the first connecting piece axially. The first positioning plate corresponds to the shape of the first positioning hole, and the diameter increases sequentially from the handwheel end to the connector end.

7. The sealing welding fixture for the lubricating oil metal shavings sensor according to claim 1, characterized in that: The upper part of the movable bracket is provided with a stepped second positioning hole, and a second positioning plate is installed in the second positioning hole through a bearing; one end of the second positioning plate is located in the second positioning hole, and the other end is provided with a positioning groove for positioning the second connecting piece.

8. The sealing welding fixture for the lubricating oil metal shavings sensor according to claim 2, characterized in that: The piston rod at the telescopic end of the clamping device contacts the end face of the second connector through the second positioning hole, and the contact end of the piston rod is a spherical contact head.

9. A sealing welding method for a lubricating oil metal shavings sensor, characterized in that: Using the sealing welding fixture of the lubricating oil metal shavings sensor according to any one of claims 1-8, the following steps are completed: S1. Place the tube inside the sensor body and insert both ends of the tube into the first inner holes of the two flanges to be welded. Connect the left flange to the first connector and the right flange to the second connector to form a sensor assembly. S2. Place the first connector and the second connector at both ends of the sensor assembly into the positioning slots of the first positioning plate and the second positioning plate, respectively, and axially lock the sensor assembly by adjusting the position of the movable bracket. S3. The clamping device applies axial clamping force to the second connecting piece, causing the through pipe to radially contract and form an interference fit with the second inner hole of the flange to be welded, thereby achieving axial sealing. S4. Fill the inlet of the detection channel of the second connector with 0.5MPa to 1MPa compressed air, and apply soapy water to the gap between the flange to be welded and the sensor body to be welded to observe the bubbles and determine whether the air tightness test is qualified. S5. After the airtightness test is passed, the clamping device maintains the clamping force in S3 and uses welding equipment to spot weld the gap to be welded; after spot welding is completed, the clamping device is depressurized to 30% to 50% of the original clamping force, and the gap to be welded is welded around the entire circle. S6. After welding is completed, remove the sensor assembly and perform an airtightness test on the welded sensor to determine whether the sensor's sealing performance is up to standard.

10. The sealing welding method for the lubricating oil metal shavings sensor according to claim 9, characterized in that: In S3, pressurization stops when the clamping force reaches 2.5kN, and the two ends of the pipe form an interference fit with the second inner hole of the two flanges to be welded.

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