A full-metal integrated filter core welding manufacturing method

Abstract

The application discloses a full-metal integrated filter core welding manufacturing method and belongs to the technical field of filter core precision manufacturing welding. The filter core is split into end covers, end rings, skeletons and filter cylinder independent components. A complete process of straight seam argon arc welding positioning through filter cake tooling, filter cylinder, filter cylinder two-end progressive precise necking, high-precision pre-assembly alignment, heterogeneous metal uniform-speed wire filling end face welding and coaxial tooling positioning laser ring seam welding is formed to realize full-process glue-free metal integrated sealing forming of the filter core. The application effectively solves the industry pain points of easy ablation of the existing ultra-thin filter screen, poor fusion of heterogeneous materials, large welding deformation, insufficient coaxiality precision and many welding seam sealing defects, greatly improves the high-temperature and high-pressure resistance and corrosion resistance of the filter core, the product has good consistency and high yield, and the application is suitable for large-scale batch production of full-metal filter cores of medium and large specifications and has extremely high industrial application and popularization value.

Description

Technical Field

[0001] This invention relates to the fields of precision machining of filter elements and welding manufacturing technology of dissimilar metal materials, specifically to a method for welding and manufacturing an all-metal integrated filter element. Background Technology

[0002] The conventional structure of filter elements used in industrial filtration systems consists of end caps, end rings, a frame, and a filter cartridge. Traditional filter elements generally use adhesives for bonding and sealing. Under harsh conditions such as high temperature, high pressure, and strong corrosion, the adhesive is prone to aging, failure, cracking, and detachment, resulting in filter element seal leakage, loss of filtration accuracy, and a significant reduction in service life. This makes it impossible to meet the long-term stable operation requirements of high-end and demanding operating conditions.

[0003] The existing all-metal welded filter element manufacturing process has many intractable industry pain points: 1. The filter cartridge is made of multi-layer metal woven mesh with tiny wire diameter and pleated stainless steel wire. The wall is extremely thin and easily burned through. When welding with the skeleton and end ring, which are solid components with a thickness of millimeters, the difference in thickness between dissimilar materials is extremely large, resulting in extremely poor fusion compatibility. This can easily lead to problems such as filter screen burn-out and failure of solid components to fuse. 2. The filter element has extremely high requirements for the coaxiality of the end caps, the accuracy of the inner hole sealing dimensions, and the parallelism of the end faces. Conventional welding processes result in large thermal deformation, and the finished product's dimensional and positional tolerances are seriously out of tolerance. 3. The filter element has three core sealing welds: the straight seam of the filter cartridge, the skeleton-end ring-filter cartridge end face, and the end cap-end ring. Traditional manual welding has poor consistency, many defects such as false welds and pores, and the yield of mass production is extremely low. 4. Matching welding parameters for glue-free all-metal filter elements is difficult, and there is a lack of standardized, high-precision tooling and process flow.

[0004] Based on the shortcomings of the existing technologies, this invention proposes a novel all-metal integrated filter element welding manufacturing method, which solves the long-standing technical bottleneck in the industry. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by proposing a method for welding an all-metal integrated filter element. This method enables glue-free, all-metal sealed welding of the filter element, significantly improving weld sealing reliability, finished product dimensional accuracy and coaxiality, reducing welding defect rate, enhancing the filter element's resistance to high temperature and pressure and corrosion resistance, extending its service life, and making it suitable for extremely harsh industrial filtration conditions.

[0006] The above-mentioned objective of this invention is achieved through the following technical solution: A method for welding and manufacturing an all-metal integrated filter element, the filter element comprising an end cap, an end ring, a frame, and a filter cartridge; the filter cartridge is formed by pleating and rolling multiple layers of micro-diameter metal filter mesh, and the end cap, end ring, and frame are made of stainless steel; the filter element has three core sealing welding positions: a straight seam sealing weld on the filter cartridge, a frame-end ring-filter cartridge end face sealing weld, and an end cap-end ring sealing weld; the manufacturing steps include: Step 1: First, pleat the filter screen to form a filter cake. After rolling the filter cake into a circle, align the two pairs of joints and then use argon arc welding to complete the straight seam sealing welding of the filter cake. Step 2: Using a self-made necking and forming equipment, the necking and forming of both ends of the filter cartridge is gradually completed by multiple small-amplitude reciprocating feeds along the radial direction and unidirectional force regularization. Step 3: Machining the skeleton, end ring, and end cap, wherein an inner chamfer is pre-made on one side of the inner hole of the end ring; Step 4: Perform high-precision pre-assembly of the filter cartridge, frame, and upper and lower end rings, and adjust to ensure that the dimensions of the filter cartridge extending out of the frame end face are consistent at both ends; Step 5: Use a uniform speed oscillating filler wire argon arc welding process to complete the full-circle sealing welding of the end faces of the filter cartridge, frame, and end ring. Step 6: The two end caps are coaxially positioned at both ends of the assembly after welding in Step 5, and the circumferential seam welding between the end caps and the end rings is completed by laser welding to obtain the finished all-metal integrated filter element.

[0007] Furthermore, step 1 includes: before welding after the filter cake is rolled into a circle, the two pairs of joints of the filter cake are aligned by using a level plate, a shim plate, a clamping fixture made of chromium zirconium copper, and a manual trimming tool. The specific process is as follows: First, insert a shim into the nearest pair of opposite pleated grooves to the two pairs of joints to form a shim; then, use a chromium zirconium copper clamping fixture to clamp the joints, at which point a portion of the two pairs of joints protrudes from the top of the clamping fixture; then, insert the protruding portions of the two pairs of joints into slots on a contour plate; then, use a self-made hand trimming tool to cut off the portions of the two pairs of joints outside the contour plate to align the two pairs of joints.

[0008] Moreover, the manual trimming tool consists of two handles and a trimming blade connected to one end of the two handles.

[0009] Furthermore, the welding process parameters used in step 1 are as follows: welding current 10A, welding speed 1mm / s, tungsten electrode diameter Φ2mm, tungsten electrode distance from filter screen end face 2-4mm, argon flow rate 5-8L / min, and filter material extension from clamping fixture 2mm.

[0010] Furthermore, the self-made necking forming equipment used in step 2 includes an outer cylinder, a worktable, multiple sliding forming modules, and a worktable lifting drive mechanism; the inner wall surface of the outer cylinder adopts a conical surface that is smaller at the top and larger at the bottom; the worktable is located in the middle of the outer cylinder, and its lower end is connected to the worktable lifting drive mechanism; a central boss is provided on the worktable, and the outer diameter of the central boss matches the outer diameter of the skeleton, which is used to limit the inner diameter of the filter cartridge during the necking forming process; multiple radial guide grooves are provided around the central boss in the worktable along the circumferential direction, and a sliding forming module is slidably installed in each radial guide groove along the radial direction. The inner end of the sliding forming module adopts a necking action surface that matches the necking shape of the filter cartridge, and the outer end face of the sliding forming module adopts an inclined surface that is combined with the inner wall surface of the outer cylinder; a tension spring is also connected to each sliding forming module to keep the outer end face of the multiple sliding forming modules in contact with the inner wall surface of the outer cylinder at all times.

[0011] Furthermore, the lifting drive mechanism of the worktable can be, but is not limited to, a hydraulic cylinder, and the lifting and lowering can be controlled by an electromagnetic reversing valve.

[0012] Furthermore, a receiving cavity is provided at the lower end of the sliding forming module, and the tension spring is placed in the receiving cavity. The inner end of the tension spring is connected to the inner hanging spring part fixed on the side wall of the receiving cavity, and the outer end of the tension spring is connected to the boss inserted into the receiving cavity through the outer hanging spring part. The boss is fixed on the worktable.

[0013] Furthermore, step 2, the necking and shaping process, specifically includes: Step 2.1: With the worktable in the lower working state, install one end of the filter cartridge onto the central boss of the equipment. At this time, multiple sliding forming modules are located in the outer working position in the radial direction under the action of their respective spring tensions. Step 2.2: Start the worktable lifting mechanism to make the worktable reciprocate and lift in a way that gradually increases the stroke, drive multiple sliding forming modules to tighten in a radial direction with gradually increasing amplitude, and apply a uniform tightening force to the end of the filter cartridge through the constriction action surface arranged in sequence along the circumference to achieve multiple gradual shrinkage. Step 2.3: After one end of the filter cartridge is narrowed, move the worktable to the lower working position, remove the filter cartridge, flip it over, and then reinstall the other end of the filter cartridge on the central boss of the equipment. Following the method in Step 2, gradually narrow the other end of the filter cartridge multiple times to complete the narrowing and forming of both ends of the filter cartridge.

[0014] Furthermore, step 4 includes: Step 4.1: Insert part of the frame into the filter cartridge from the bottom. Manually tighten one end ring onto the upper constricted part of the filter cartridge to achieve precise fitting of the upper end ring. Step 4.2: Then, push the frame upwards using the tooling, so that the upper end of the frame extends a certain distance from the upper end of the filter cartridge; so that the frame, filter cartridge, and upper ring are tightly assembled. Step 4.3: Then, manually tighten the other end ring onto the lower constricted part of the filter cartridge to achieve precise fitting of the lower end ring. Step 4.4: Push the frame into the filter cartridge from the opposite direction to achieve a tight assembly between the frame, filter cartridge, and end rings; and perform final leveling to ensure that the protrusion dimensions of the filter cartridge above the frame end face are consistent.

[0015] Furthermore, the welding parameters used in step 5 are as follows: welding current 95A, welding torch oscillation angle 5°, oscillation speed 30° / s, filter element rotation speed 4.5° / s, filter element longitudinal rotation angle 363°, filler wire is 304 material Φ1.2mm gas shielded welding wire, filler wire speed 10mm / s, argon flow rate 8-10L / min, filter cartridge end face is 2-3mm higher than end ring end face; and welding torch tungsten electrode is 2-3mm higher than filter cartridge end face, welding torch center is offset 1.5mm from filter cartridge center towards end ring side for welding.

[0016] The advantages and positive effects of this invention are as follows: 1. This invention has no adhesive structure throughout the entire process, and is sealed as a whole metal unit, which can be adapted to extreme and harsh working conditions such as high temperature, high pressure, and strong corrosion for a long time, greatly extending the service life of the filter element; 2. In the filter cartridge end necking forming process, the present invention adopts an original progressive necking process and special positioning tooling, which completely solves the defects of traditional process such as random folds, weld porosity and excessive gaps, and greatly improves the welding sealing strength and density. 3. This invention employs an argon arc + laser composite welding process for dissimilar metals, perfectly solving the problem of fusing ultra-thin filter screens with thick solid components and eliminating the risk of filter screen burn-out and scrapping.

[0017] 4. The coaxiality of the entire process is precisely controllable. The coaxiality and inner hole sealing dimensions of the finished end cap meet industry standards remotely, eliminating the need for subsequent secondary precision machining. 5. The process flow of this invention is standardized and the parameters are controllable, resulting in good consistency and high yield in batch production, which significantly reduces production rework costs; 6. The finished filter element of this invention fully meets the stringent requirements of high-end industrial filtration in terms of filtration accuracy, external dimensions, and initial bubble point integrity. Attached Figure Description

[0018] Figure 1 This is a half-sectional view of the all-metal integrated filter element of the present invention. Figure 2 This is a reference diagram showing the usage state of the pad plate used in the filter cartridge manufacturing process of the present invention; Figure 3This is a reference diagram showing the usage state of the contour plate used in the filter cartridge manufacturing process of this invention; Figure 4 This is a photograph of the self-made hand trimming tool of this invention; Figure 5 This is a reference diagram showing the alignment of the two end joints during the manufacturing process of the filter cartridge according to the present invention; Figure 6 This is a diagram illustrating the effect of straight-seam welding of the filter cake according to the present invention. Figure 7 This is a physical image and a reference image of the clamping and correction tooling used in the filter cartridge manufacturing process of the present invention. The left view is the physical image, and the right view is the reference image of the usage state. Figure 8 This is a top view (of the device used for necking and forming according to the present invention). Figure 9 This is a simplified cross-sectional view of the special equipment for necking and forming according to the present invention; Figure 10 This is a diagram showing the finished effect of the reduced openings at both ends of the filter cartridge of the present invention; Figure 11 This is a reference diagram of the first step of high-precision pre-assembly of the filter cartridge, frame, and upper and lower end rings in this invention; Figure 12 This is a reference diagram of the second step of the high-precision pre-assembly of the filter cartridge, frame and upper and lower end rings of the present invention; Figure 13 This is a reference diagram of the third step of the high-precision pre-assembly of the filter cartridge, frame and upper and lower end rings of the present invention; Figure 14 This is a reference diagram for the fourth step of the high-precision pre-assembly of the filter cartridge, frame, and upper and lower end rings in this invention; Figure 15 This is a schematic diagram of the operation of the automated welding equipment for sealing welding of the filter cartridge, frame and end ring end face according to the present invention; Figure 16 This is a schematic diagram of the welding positioning for the end face of the present invention; Figure 17 This is a diagram showing the appearance of the weld seam at the end face of the present invention. Figure 18 This is a structural diagram of the coaxiality auxiliary welding fixture of the present invention; Figure 19 This is an overall cross-sectional view of the all-metal integrated filter element of the present invention; Figure 20 A schematic diagram of the finished all-metal integrated filter element of this invention. Detailed Implementation

[0019] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0020] For a method of welding and manufacturing an all-metal integrated filter element, please refer to [link / reference]. Figures 1-20 The filter element involved in this method consists of a filter cartridge 4, a frame 3, an end ring 2, and an end cap 1. The filter cartridge is made of single or multiple layers of stainless steel woven mesh, woven from fine metal wires and then pleated, belonging to micro-filament metal filter elements. The end cap, end ring, and frame are all made of stainless steel. The filter element has three core sealing welding positions: the straight seam sealing weld of the filter cartridge, the frame-end ring-filter cartridge end face sealing weld, and the end cap and end ring sealing weld. The manufacturing method includes the following core processes: Step 1: Filter cartridge fabrication and straight seam argon arc welding; Step 2: Gradually narrow the ends of the filter cartridge to form the filter cartridge; Step 3: Precision prefabrication of the skeleton, end ring, and end cap; Step 4: Perform high-precision pre-assembly of the filter cartridge, frame, and upper and lower end rings; Step 5: Automated uniform speed scanning and wire filling welding of filter cartridge-frame-end ring end face; Step 6: Coaxially position the end caps and perform laser welding; Step 7: Finished product inspection and verification.

[0021] Step 1, filter cartridge fabrication and straight seam argon arc welding, includes the following steps: Step 1.1. After pleating the multi-layer filter screen, it is then trimmed and pleated to form a filter cake; Step 1.2: Roll the filter cake into a circle, align the two ends, and seal the weld seam with argon arc welding to avoid the operational limitations of resistance welding. In step 1.2, the method for aligning the two pairs of joints after the filter cake is rolled into a circle before welding is as follows: First, insert the pad plate 5 into the set of opposite pleated grooves closest to the two pairs of joints to form a pad; then, use the chromium zirconium copper clamping fixture 7 to clamp the joints, at which point a part of the two pairs of joints extends out from the upper end of the clamping fixture; then, insert the extended parts of the two pairs of joints into the slots on a contour plate 6; then, use a self-made manual trimming tool to cut off the parts of the two pairs of joints outside the contour plate to align the two pairs of joints, ensuring neat pleats and uniform stress; finally, remove the contour plate for welding, and after welding, loosen the clamping fixture and the pad plate.

[0022] The homemade trimming tool consists of two handles and a trimming blade connected to one end of each handle. It is simple in structure and easy to use.

[0023] In step 1.2, the core welding process parameters are: welding current 10A, welding speed 1mm / s, tungsten electrode diameter Φ2mm, tungsten electrode distance from filter screen end face 2-4mm, argon flow rate 5-8L / min, filter material protruding from clamping fixture with a 2mm allowance; and a dedicated platform is used to ensure uniform and stable welding speed. In step 1.2, after welding, a clamping and correction fixture is used to clamp and correct the filter cartridge weld, ensuring uniform folds in adjacent weld areas. This guarantees a uniform and neat overall clamping of the filter cake, preventing excessive gaps in subsequent narrowing processes. The clamping and correction fixture is implemented by welding two parallel, outward-extending clamping plates onto the two clamps of an existing vise.

[0024] Step 2: Gradual necking at both ends of the filter cartridge The filter cartridge is formed by shrinking and shaping using a self-made shrinking and shaping device 8. The core structure of this device includes an outer cylinder 8-1, a worktable 8-3, multiple sliding forming modules 8-2, and a worktable lifting and driving mechanism (not shown in the attached drawings).

[0025] The inner wall of the outer cylinder is a tapered surface, wider at the bottom and narrower at the top. The worktable is located in the middle of the outer cylinder, and its lower end is connected to a lifting drive mechanism. This lifting drive mechanism can be, but is not limited to, a hydraulic cylinder, and its lifting and lowering are controlled by an electromagnetic directional valve. A central boss 8-4 is provided on the worktable, its outer diameter matching the outer diameter of the frame, used to limit the inner diameter of the filter cartridge during the necking process. Multiple radial guide grooves are arranged circumferentially around the central boss within the worktable. A sliding forming module is slidably installed radially within each radial guide groove. The inner end of the sliding forming module has a necking action surface that matches the necking shape of the filter cartridge. The outer end face of the sliding forming module is an inclined surface that engages with the inner wall of the outer cylinder. During the upward movement of the worktable and multiple sliding forming modules driven by the lifting drive mechanism, the multiple sliding forming modules are acted upon by the inner wall of the outer cylinder, resulting in synchronous centripetal movement, thus achieving necking forming of the ends of the filter cartridges inserted between the multiple sliding forming modules. To ensure that the outer end faces of multiple sliding forming modules are always in contact with the inner wall of the outer cylinder, thereby adjusting the size of the narrowing formed by the narrowing action surfaces of multiple sliding forming modules, a tension spring 8-5 is connected to each sliding forming module. Specifically, a receiving cavity 8-2-1 is provided at the lower end of the sliding forming module. The tension spring is placed in the receiving cavity. The inner end of the tension spring is connected to the inner hanging spring part (which can be a hanging spring post) fixed on the side wall of the receiving cavity. The outer end of the tension spring is connected to the boss inserted into the receiving cavity through the outer hanging spring part (which can also be a hanging spring post). The boss is fixed on the worktable.

[0026] In this invention, the worktable is composed of a worktable base and a worktable cover connected by screws. The central boss and radial guide groove are provided on the worktable base.

[0027] This invention employs a conical surface limiting drive method to achieve precise radial feeding of the mold.

[0028] The filter cartridge is progressively narrowed at both ends using the self-made necking forming equipment described above. The specific forming process is as follows: Step 2.1: With the worktable in the lower working state, before the necking, install one end of the filter cartridge on the central boss of the equipment. At this time, multiple sliding forming modules are located in the outer working position in the radial direction under the action of their respective spring tension. Step 2.2: Activate the worktable lifting mechanism to make the worktable reciprocate and lift in a gradually increasing stroke manner, thereby driving multiple sliding forming modules to synchronously tighten in a gradually increasing radial direction. Through the shrinking action surfaces arranged sequentially along the circumference, a uniform tightening force is applied to the end of the filter cartridge, achieving multiple gradual shrinkages. Throughout the process, the filter cartridge is always subjected to unidirectional force along the same circumference, resulting in neat folds and avoiding random folds and collapses. After the shrinking is completed, the inner diameter of the filter cartridge and the outer diameter of the frame are precisely matched, and the end of the filter cartridge is tightly fitted with the inner chamfer of the end ring. The assembly gap between the three is extremely small, providing a perfect foundation for subsequent end face welding. This completely solves the defects such as uneven shrinking, random folds, and end face welding porosity caused by single strong compression.

[0029] Step 2.3: After one end of the filter cartridge is narrowed, move the worktable to the lower working position, remove the filter cartridge, flip it over, and then reinstall the other end of the filter cartridge on the central boss of the equipment. Following the method in Step 2.2, gradually narrow the other end of the filter cartridge multiple times to complete the narrowing and forming of both ends of the filter cartridge.

[0030] Step 3: Pre-fabrication of skeleton, end ring and end cap The frame, end ring, and end cap are directly precision machined and formed without the need to reserve a large amount of welding deformation allowance. The welding process and tooling limit of this invention suppress welding deformation throughout the process, and the cost, dimensional accuracy, and geometric tolerances are controllable throughout the process. The inner hole on one side of the end ring is pre-chamfered to precisely fit the conical surface of the filter cartridge and precisely control the total length of the finished filter element.

[0031] Step 4: Perform high-precision pre-assembly of the filter cartridge, frame, and upper and lower end rings, specifically including: Step 4.1: Insert part of the frame into the filter cartridge from the bottom. Manually tighten one end ring onto the upper constricted part of the filter cartridge to achieve precise fitting of the upper end ring.

[0032] Step 4.2: Then, push the frame upwards using the tooling, so that the upper end of the frame extends a certain distance from the upper end of the filter cartridge; so that the frame, filter cartridge, and upper ring are tightly assembled. Step 4.3: Then, manually tighten the other end ring onto the lower constricted part of the filter cartridge to achieve precise fitting of the lower end ring. Step 4.4: Push the frame into the filter cartridge from the opposite direction to achieve a tight assembly between the frame, filter cartridge, and end rings; and perform final leveling to ensure that the protrusion dimensions of the filter cartridge at both ends above the frame end face are consistent, ensuring the overall coaxiality of the foundation and preventing subsequent welding eccentricity deviations.

[0033] Step 5: Sealing welding of the filter cartridge, frame, and end ring face, specifically as follows: 1. The uniform speed variable angle uniform speed wire feeding scanning oscillating fusion welding equipment is adopted. The welding torch can oscillate at a uniform speed, the filter cartridge can rotate at a uniform speed, and it has the functions of precise wire feeding and welding torch position adjustment. 2. Core benchmark welding parameters: welding current 95A, welding torch oscillation angle 5°, oscillation speed 30° / s, filter element rotation speed 4.5° / s, filter element longitudinal rotation angle 363°, filler wire is 304 material Φ1.2mm gas shielded welding wire, filler wire speed 10mm / s, argon flow rate 8-10L / min, filter cartridge end face is 2-3mm higher than end ring end face; 3. Bend the wire feed tube, with the copper nozzle pointing downwards at an angle, and precisely align it below the tungsten inert gas pool; 4. A three-jaw self-centering clamping fixture made of chromium zirconium copper is used to clamp and protect the outer circle and end face of the end ring, preventing the end ring end face from being melted during welding; 5. The tungsten electrode of the welding torch should be 2-3mm higher than the end face of the filter cartridge, and the center of the welding torch should be offset 1.5mm from the end ring side relative to the center of the filter cartridge when welding. 6. After completing the full-circle sealing welding of one end face, flip the filter element and repeat the process to complete the welding of the other end. The weld is uniform and dense, without burn-through, pores, or incomplete fusion defects.

[0034] Step 6: Position the end caps coaxially at both ends of the assembly after welding in Step 5, and perform laser welding on the mating parts of the end caps and the corresponding end rings along the circumferential direction.

[0035] 1. The inner holes of the end caps at both ends of the filter element are the sealing reference positions. The dimensional accuracy and coaxiality of both ends are subject to strict requirements. The welding process requires minimal thermal deformation to avoid damaging the machined precision inner holes. 2. The present invention preferably uses laser welding technology, which has a lower threshold and stronger adaptability compared to electron beam welding, with extremely small heat input and controllable welding deformation; 3. A dedicated coaxiality auxiliary welding fixture 9 was independently designed to strictly limit the position of the end caps at both ends, ensuring that the coaxiality tolerance of the end caps at both ends is ≤0.015mm.

[0036] The coaxiality auxiliary welding fixture includes a positioning shaft and a locking nut (not shown in the attached drawings). The positioning shaft consists of a clamping head portion 9-1, a threaded head portion 9-3, and a main shaft body portion 9-2 positioned between the clamping head and the threaded head. The diameter of the clamping head portion is the same as the diameter of the large hole 1-1 on the end cap, but the length of the clamping head portion is greater than the depth of the large hole 1-1 on the end cap, allowing a portion of the clamping head to extend from the end cap for clamping. The diameter of the main shaft body portion can form a clearance fit with the diameter of the small holes 1-2 on both ends of the end cap, ensuring the coaxiality of the end caps after assembly through a very small clearance fit. The threaded head portion is connected to the locking nut to achieve axial fixation of the coaxiality auxiliary welding fixture and the filter element.

[0037] 4. The filter element is held in place by a coaxial welding fixture and rotated at a constant speed. The laser welding gun is used to complete the sealing welding of the entire end ring seam between the end cap and the end ring. 5. After welding, the finished filter element meets all the standards in terms of shape and position tolerance, sealing accuracy, and appearance dimensions.

[0038] Example: Taking a stainless steel pleated filter element for a fuel system as an example, the filter cartridge has 40-mesh 304 stainless steel mesh inside and out, a woven mesh in the middle layer, and the end caps, rings, and frame are made of 304 stainless steel. The process is completed sequentially according to the above S1-S6 process flow, using the special tooling and customized welding parameters of this invention throughout the process. The finished filter element testing results are as follows: The coaxiality of the end caps is ≤0.015mm. The three welds are 100% free of porosity and incomplete welds, and are sealed and pressure-resistant with no leakage. The filter element is resistant to high temperatures of 350℃ and pressure of 15MPa, with no sealing failure.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for welding and manufacturing an all-metal integrated filter element, characterized in that: The filter element includes an end cap, an end ring, a frame, and a filter cartridge; the filter cartridge is made of multiple layers of fine-diameter metal filter mesh pleated and rolled; the end cap, end ring, and frame are made of stainless steel; the filter element has three core sealing welding positions: a straight seam sealing weld on the filter cartridge, a sealing weld between the frame and the end ring and the end cartridge end face, and a sealing weld between the end cap and the end ring; the manufacturing steps include: Step 1: The filter screen is pleated to form a filter cake. Argon arc welding is used to complete the straight seam sealing welding of the filter cake. During welding, it is positioned in conjunction with contour plates, gasket plates, and clamping fixtures made of chromium zirconium copper. Step 2: Using a self-made necking and forming equipment, the necking and forming of both ends of the filter cartridge is gradually completed by multiple small-amplitude reciprocating feeds along the radial direction and unidirectional force regularization. Step 3: Machining the skeleton, end ring, and end cap, wherein an inner chamfer is pre-made on one side of the inner hole of the end ring; Step 4: Perform high-precision pre-assembly of the filter cartridge, frame, and upper and lower end rings, and adjust to ensure that the dimensions of the filter cartridge extending out of the frame end face are consistent at both ends; Step 5: Use a uniform speed oscillating filler wire argon arc welding process to complete the full-circle sealing welding of the end faces of the filter cartridge, frame, and end ring. Step 6: The two end caps are coaxially positioned at both ends of the assembly after welding in Step 5, and the circumferential seam weld between the end caps and the end ring is completed by laser welding to obtain the finished all-metal integrated filter element.

2. The method for welding and manufacturing an all-metal integrated filter element according to claim 1, characterized in that: Step 1 includes: before welding after the filter cake is rolled into a circle, the two pairs of joints of the filter cake are aligned by using a level plate, a shim plate, a clamping fixture made of chromium zirconium copper, and manual trimming tools. The specific process is as follows: First, a shim plate is inserted into the nearest set of opposite pleats to level the two pairs of joints. Then, a chromium zirconium copper clamping fixture is used to clamp the joints, at which point a portion of the two pairs of joints protrudes from the top of the clamping fixture. Next, the protruding portions of the two pairs of joints are inserted into slots on a contour plate. Then, a self-made hand trimming tool is used to cut off the portions of the two pairs of joints outside the contour plate to align the two pairs of joints.

3. The method for welding and manufacturing an all-metal integrated filter element according to claim 2, characterized in that: The manual trimming tool consists of two handles and a trimming blade connected to one end of each handle.

4. The method for welding and manufacturing an all-metal integrated filter element according to claim 1, characterized in that: In step 1, the welding process parameters used are: welding current 10A, welding speed 1mm / s, tungsten electrode diameter Φ2mm, tungsten electrode distance from filter screen end face 2-4mm, argon flow rate 5-8L / min, and filter material extension from clamping fixture 2mm.

5. The method for welding and manufacturing an all-metal integrated filter element according to claim 1, characterized in that: The self-made necking forming equipment used in step 2 includes an outer cylinder, a worktable, multiple sliding forming modules, and a worktable lifting drive mechanism. The inner wall of the outer cylinder is a tapered surface that is smaller at the top and larger at the bottom. The worktable is located in the middle of the outer cylinder, and its lower end is connected to the worktable lifting drive mechanism. A central boss is provided on the worktable, and the outer diameter of the central boss matches the outer diameter of the frame, which is used to limit the inner diameter of the filter cartridge during the necking forming process. Multiple radial guide grooves are provided around the central boss in the worktable along the circumferential direction. A sliding forming module is slidably installed in each radial guide groove. The inner end of the sliding forming module adopts a necking action surface that matches the necking shape of the filter cartridge, and the outer end face of the sliding forming module adopts an inclined surface that is combined with the inner wall surface of the outer cylinder. A tension spring is also connected to each sliding forming module to keep the outer end face of the multiple sliding forming modules in contact with the inner wall surface of the outer cylinder.

6. The method for welding and manufacturing an all-metal integrated filter element according to claim 5, characterized in that: The lifting and lowering drive mechanism of the worktable can be a hydraulic cylinder, and the lifting and lowering can be controlled by an electromagnetic reversing valve.

7. The method for welding and manufacturing an all-metal integrated filter element according to claim 5, characterized in that: A receiving cavity is provided at the lower end of the sliding forming module. The tension spring is placed in the receiving cavity. The inner end of the tension spring is connected to the inner hanging spring part fixed on the side wall of the receiving cavity. The outer end of the tension spring is connected to the boss inserted into the receiving cavity through the outer hanging spring part. The boss is fixed on the worktable.

8. The method for welding and manufacturing an all-metal integrated filter element according to claim 5, characterized in that: Step 2, the necking and shaping process, specifically includes: Step 2.1: With the worktable in the lower working state, install one end of the filter cartridge onto the central boss of the equipment. At this time, multiple sliding forming modules are located in the outer working position in the radial direction under the action of their respective spring tensions. Step 2.2: Start the worktable lifting mechanism to make the worktable reciprocate and lift in a way that gradually increases the stroke, drive multiple sliding forming modules to tighten in a radial direction with gradually increasing amplitude, and apply a uniform tightening force to the end of the filter cartridge through the constriction action surface arranged in sequence along the circumference to achieve multiple gradual shrinkage. Step 2.3: After one end of the filter cartridge is narrowed, move the worktable to the lower working position, remove the filter cartridge, flip it over, and then reinstall the other end of the filter cartridge onto the central boss of the equipment. Following the method in Step 2.2, gradually narrow the other end of the filter cartridge multiple times to complete the narrowing and forming of both ends of the filter cartridge.

9. The method for welding and manufacturing an all-metal integrated filter element according to claim 1, characterized in that: Step 4 includes: Step 4.1: Insert part of the frame into the filter cartridge from the bottom. Manually tighten one end ring onto the upper constricted part of the filter cartridge to achieve precise fitting of the upper end ring. Step 4.2: Then, push the frame upwards using the tooling, so that the upper end of the frame extends a certain distance from the upper end of the filter cartridge; so that the frame, filter cartridge, and upper ring are tightly assembled. Step 4.3: Then, manually tighten the other end ring onto the lower constricted part of the filter cartridge to achieve precise fitting of the lower end ring. Step 4.4: Push the frame into the filter cartridge from the opposite direction to achieve a tight assembly between the frame, filter cartridge, and end rings; and perform final leveling to ensure that the protrusion dimensions of the filter cartridge above the frame end face are consistent.

10. The method for welding and manufacturing an all-metal integrated filter element according to claim 1, characterized in that: The welding parameters used in step 5 are as follows: welding current 95A, welding torch oscillation angle 5°, oscillation speed 30° / s, filter element rotation speed 4.5° / s, filter element longitudinal rotation angle 363°, filler wire is 304 material Φ1.2mm gas shielded welding wire, filler wire speed 10mm / s, argon flow rate 8-10L / min, filter cartridge end face is 2-3mm higher than end ring end face; and welding torch tungsten electrode is 2-3mm higher than filter cartridge end face, welding torch center is offset 1.5mm from filter cartridge center towards end ring side for welding.

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