A return air filter assembly for a heat treatment cycle apparatus

Abstract

The utility model provides a kind of air return filter assembly of heat treatment circulating device, belong to air return filter technical field, the air return filter assembly of this heat treatment circulating device, including filter casing and the filter screen plate being set in filter casing inside, the filter casing has air inlet and air outlet, the filter screen plate separates filter casing inside into air inlet cavity and air outlet cavity, the edge of the filter screen plate is provided with annular sealing flange, the annular sealing flange is closely combined with the inner wall surface of filter casing, the length of the annular sealing flange along the circumferential extension of filter screen plate is greater than 85% of the perimeter of filter screen plate edge, the central region of the filter screen plate is provided with reinforcing rib plate, the reinforcing rib plate is radially distributed, one end of the reinforcing rib plate is connected with the geometric center of filter screen plate, the other end of the reinforcing rib plate extends to the inner side edge of annular sealing flange.

Description

Technical Field

[0001] This utility model belongs to the field of return air filtration technology, specifically, it relates to a return air filtration component of a heat treatment circulation device. Background Technology

[0002] In heat treatment circulation systems, the return air filter assembly is a key component for ensuring a clean processing environment and stable processes. Its main function is to filter the circulating return air, removing particulate matter, scale, dust, and other impurities from the air, preventing these impurities from entering the surface of the heat-treated workpiece or depositing on the heating elements, thus affecting heat transfer efficiency. Currently, widely used heat treatment circulation systems in industrial production include heat treatment furnaces, tempering furnaces, and annealing furnaces. These devices typically employ forced convection circulation, using a fan to drive hot air to circulate within a closed space, achieving uniform heating or cooling of the workpiece. During the circulation process, the return air inevitably carries various impurities, therefore, a return air filter assembly is necessary to purify the airflow. Existing return air filter assemblies typically employ a simple frame structure, fixing the filter screen to the frame and then installing the entire assembly in the air duct. The main problem with this structure is the poor sealing effect between the filter screen and the housing, allowing airflow to easily bypass the gaps at the edges of the filter screen, resulting in a significant proportion of the airflow entering the circulation system unfiltered, greatly reducing filtration efficiency. Meanwhile, the filter screen lacks effective support when subjected to airflow pressure, making it prone to deformation, vibration, and even breakage after prolonged use. This not only affects the filtration effect but may also cause broken screen fragments to enter the circulation system, damaging the equipment. Although some designs attempt to improve the sealing effect by adding gaskets or using compression devices, these methods are often complex in structure, difficult to assemble, and costly. Moreover, gaskets are prone to aging and failure under high-temperature environments, requiring frequent replacement, which increases maintenance workload and operating costs. Utility Model Content

[0003] In view of this, the present invention provides a return air filter assembly for a heat treatment circulation device, which can solve the technical problem that the existing heat treatment circulation device return air filter assembly has poor sealing between the filter screen and the shell, resulting in airflow bypass and reduced filtration efficiency. At the same time, the filter screen is prone to deformation and vibration under long-term airflow pressure, which affects the service life and filtration effect stability of the filter assembly.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a return air filter assembly for a heat treatment circulation device, including a filter housing and a filter screen plate disposed inside the filter housing. The filter housing has an air inlet and an air outlet. The filter screen plate divides the interior of the filter housing into an air inlet chamber and an air outlet chamber. The filter screen plate has an annular sealing flange on its edge, which is tightly fitted to the inner wall of the filter housing. The length of the annular sealing flange extending circumferentially along the filter screen plate is greater than 85% of the circumference of the filter screen plate edge. A reinforcing rib plate is disposed in the central area of ​​the filter screen plate. The reinforcing rib plates are radially distributed, with one end of the reinforcing rib plate connected to the geometric center of the filter screen plate and the other end of the reinforcing rib plate extending to the inner edge of the annular sealing flange.

[0006] The technical advantages of the return air filter assembly of the heat treatment circulation device provided by this utility model are as follows: By setting an annular sealing flange at the edge of the filter screen and ensuring its tight fit with the inner wall of the filter housing, airflow can be effectively prevented from bypassing the edge of the filter screen, ensuring that all incoming airflow must pass through the filter screen for filtration, thus improving filtration efficiency. The annular sealing flange extends circumferentially for more than 85% of the circumference of the filter screen edge, ensuring reliable sealing. Simultaneously, radially distributed reinforcing ribs extend from the geometric center to the inner edge of the annular sealing flange, providing uniform support for the filter screen, preventing deformation or vibration under airflow pressure, and extending the service life of the filter assembly.

[0007] Based on the above technical solution, the return air filter assembly of the heat treatment circulation device of this utility model can be further improved as follows:

[0008] The annular sealing flange has a trapezoidal cross-section, with the upper bottom surface of the trapezoidal structure connected to the edge of the filter screen and the lower bottom surface of the trapezoidal structure in contact with the inner wall of the filter housing.

[0009] The beneficial effects of adopting the above-mentioned improved scheme are as follows: The annular sealing flange adopts a trapezoidal cross-section structure. The upper bottom surface connects with the edge of the filter screen to form a stable structural foundation, while the lower bottom surface contacts the inner wall of the filter housing, providing a larger contact area and enhancing the sealing effect. The trapezoidal structure allows the stress generated by the annular sealing flange under airflow pressure to be evenly distributed, avoiding the sealing failure problem caused by stress concentration. At the same time, the gradual change characteristic of the trapezoidal structure provides a guiding effect during assembly, facilitating the installation and positioning of the filter screen.

[0010] Furthermore, the number of reinforcing ribs is 6 to 8, the included angle between two adjacent reinforcing ribs is equal, and the reinforcing ribs are arranged perpendicular to the plane of the filter screen.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: setting the number of reinforcing ribs to 6 to 8 and ensuring that the included angle between adjacent reinforcing ribs is equal achieves uniform support for the filter screen, avoiding deformation caused by insufficient support in local areas. The reinforcing ribs are set perpendicular to the plane of the filter screen, effectively resisting airflow pressure perpendicular to the plane of the screen, while not affecting the airflow through the filter screen. This ensures a balance between pressure resistance and ventilation efficiency in the filter assembly, allowing the filter screen to remain flat and stable during long-term use.

[0012] Furthermore, the air inlet and air outlet of the filter housing are located on opposite sides of the filter housing, and the opening area of ​​the air inlet is smaller than the opening area of ​​the air outlet.

[0013] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: Positioning the air inlet and outlet on opposite sides of the filter housing creates a straight-through airflow channel, reducing airflow twists and turbulence within the housing, thus lowering airflow resistance and energy loss. The design of the air inlet opening area being smaller than the outlet opening area allows for some diffusion space after the airflow passes through the filter screen, reducing the wind speed at the outlet and decreasing noise generation. Simultaneously, the smaller air inlet area concentrates the incoming airflow, improving the utilization rate of the filter screen.

[0014] Furthermore, the thickness of the filter screen is less than the thickness of the reinforcing rib, and the height of the reinforcing rib is 3 to 5 times the thickness of the filter screen.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: By controlling the thickness of the filter screen to be less than the thickness of the reinforcing rib, sufficient air permeability and low flow resistance are ensured for the filter screen, while the larger thickness of the reinforcing rib provides sufficient structural strength. Setting the height of the reinforcing rib to 3 to 5 times the thickness of the filter screen ensures that the reinforcing rib has sufficient rigidity to resist bending deformation. This size ratio ensures structural stability while avoiding material waste and airflow interference caused by excessively high reinforcing ribs, achieving an optimized balance between structural strength and economy.

[0016] Furthermore, the outer surface of the annular sealing flange is provided with a plurality of arc-shaped grooves, which are evenly distributed along the circumference of the annular sealing flange, and the radius of curvature of the arc-shaped grooves is adapted to the radius of curvature of the inner wall surface of the filter housing.

[0017] The beneficial effects of the above-mentioned improvement scheme are as follows: Several evenly distributed circumferentially shaped arc-shaped grooves are provided on the outer surface of the annular sealing flange. The radius of curvature of the arc-shaped grooves matches the radius of curvature of the inner wall surface of the filter housing, allowing the annular sealing flange to better conform to the curved shape of the inner wall surface of the housing, eliminating gaps caused by improper surface fit. The arc-shaped grooves also act as a buffer during assembly, allowing the annular sealing flange to undergo slight elastic deformation under radial pressure, enhancing the reliability of the seal. Simultaneously, the evenly distributed grooves prevent uneven distribution of sealing pressure.

[0018] Furthermore, the filter housing is made of stainless steel, and the inner wall of the filter housing is provided with an annular positioning groove, and the annular sealing flange is embedded in the annular positioning groove.

[0019] The beneficial effects of adopting the above-mentioned improved scheme are as follows: Using stainless steel to make the filter housing gives it excellent corrosion resistance and high-temperature resistance, making it suitable for high-temperature and corrosive gases in heat treatment environments. An annular positioning groove is set on the inner wall of the housing, and an annular sealing flange is embedded within it, forming a dual function of mechanical positioning and sealing. The annular positioning groove provides circumferential and radial constraints on the annular sealing flange, preventing the filter screen from shifting or rotating under airflow impact. At the same time, the embedded structure increases the contact area and sealing pressure, further improving sealing performance and structural stability.

[0020] Furthermore, the reinforcing rib has a fan-shaped structure, the center of which coincides with the geometric center of the filter screen, and the edge of the reinforcing rib is arc-shaped.

[0021] The beneficial effects of adopting the above-mentioned improved scheme are as follows: Designing the reinforcing ribs as a fan-shaped structure with the center coinciding with the geometric center of the filter screen allows the ribs to radiate outwards from the center. This structure effectively transfers the distributed load acting on the filter screen to the annular sealing flange at the edge, achieving uniform load distribution. The rounded edges of the reinforcing ribs reduce stress concentration and avoid fatigue failure easily caused by sharp-cornered structures. Simultaneously, the rounded edges minimize airflow obstruction, reducing interference with airflow and ensuring filtration efficiency.

[0022] Furthermore, the filter screen is woven from metal wire mesh with a mesh size of 0.5mm to 2mm, and the filter screen has a flat plate structure.

[0023] The beneficial effects of adopting the above-mentioned improved scheme are as follows: Using woven metal wire mesh to manufacture the filter plate provides excellent strength and high-temperature resistance, enabling it to withstand the high-temperature environment of the heat treatment circulation device. Controlling the mesh size within the range of 0.5mm to 2mm effectively filters particulate matter and impurities in the airflow while ensuring sufficient airflow and avoiding excessive flow resistance. The flat plate structure facilitates connection with the annular sealing flange and reinforcing ribs. Furthermore, the flat plate structure ensures uniform stress distribution, reducing the likelihood of localized deformation and guaranteeing the long-term stable operation of the filter assembly.

[0024] Furthermore, the ratio of the upper base width of the trapezoidal cross-section of the annular sealing flange to the thickness of the filter screen is 2:1 to 3:1, and the ratio of the lower base width to the upper base width of the trapezoidal cross-section is 1.5:1 to 2.5:1.

[0025] The beneficial effects of adopting the above-mentioned improved scheme are as follows: By precisely controlling the dimensional ratio of the trapezoidal cross-section of the annular sealing flange, the ratio of the upper base width to the filter screen thickness is made to be 2:1 to 3:1, ensuring sufficient connection strength between the annular sealing flange and the filter screen and avoiding stress concentration caused by excessive narrowness at the connection. The ratio of the lower base width to the upper base width is 1.5:1 to 2.5:1, ensuring sufficient contact area between the annular sealing flange and the inner wall of the housing, providing stable sealing pressure. This gradient transition structure allows the sealing flange to have both good sealing performance and reasonable material distribution, avoiding over-design.

[0026] Compared with existing technologies, the beneficial effects of the return air filter assembly of the heat treatment circulation device provided by this utility model are as follows: This utility model forms a reliable sealing system by setting an annular sealing flange on the edge of the filter screen and adopting a trapezoidal cross-section structure, combined with an annular positioning groove on the inner wall of the filter housing. This completely solves the problem of airflow bypass, ensuring that all incoming airflow must pass through the filter screen for effective filtration, significantly improving filtration efficiency. The radially distributed reinforcing ribs provide uniform and sufficient support for the filter screen, effectively resisting deformation and vibration caused by airflow pressure and extending the service life of the filter screen. The relative arrangement of the air inlet and outlet, as well as the differentiated design of the opening area, optimizes the airflow channel, reduces flow resistance and noise, and improves the energy efficiency of the entire circulation system. The arc-shaped groove design on the outer side of the annular sealing flange enhances the fit with the inner wall of the housing, further improving sealing reliability. The fan-shaped structure and arc-shaped edges of the reinforcing ribs ensure structural strength while reducing interference with airflow, achieving a harmonious balance between structural performance and flow performance. By precisely controlling the dimensional proportions of each component, comprehensive optimization of sealing performance, structural strength, ventilation efficiency, and material economy is achieved, enabling the filter assembly to operate stably and reliably for a long time in the high temperature, high pressure, and corrosive environment of the heat treatment cycle device. Compared with existing technologies, it has significant advantages such as good sealing performance, structural stability, high filtration efficiency, and long service life. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a return air filter assembly for a heat treatment circulation device;

[0029] Figure 2 A cross-sectional view of the return air filter assembly of a heat treatment circulation device;

[0030] Figure 3 A top view of the return air filter assembly of a heat treatment circulation device;

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 1. Filter housing; 2. Filter screen; 3. Annular sealing flange. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figures 1-3 The image shows a first embodiment of a return air filter assembly for a heat treatment circulation device provided by this utility model. In this embodiment, it includes a filter housing 1 and a filter screen 2 disposed inside the filter housing. The filter housing has an air inlet and an air outlet. The filter screen divides the interior of the filter housing into an air inlet chamber and an air outlet chamber. The filter screen has an annular sealing flange 3 on its edge. The annular sealing flange is tightly fitted to the inner wall of the filter housing. The length of the annular sealing flange extending circumferentially along the filter screen is greater than 85% of the circumference of the filter screen edge. A reinforcing rib is provided in the central area of ​​the filter screen. The reinforcing ribs are radially distributed. One end of the reinforcing rib is connected to the geometric center of the filter screen, and the other end of the reinforcing rib extends to the inner edge of the annular sealing flange.

[0035] In the above technical solution, the cross-section of the annular sealing flange is trapezoidal, the upper bottom surface of the trapezoidal structure is connected to the edge of the filter screen, and the lower bottom surface of the trapezoidal structure is in contact with the inner wall surface of the filter housing.

[0036] Furthermore, in the above technical solution, the number of reinforcing ribs is 6 to 8, the included angle between two adjacent reinforcing ribs is equal, and the reinforcing ribs are arranged perpendicular to the plane of the filter screen.

[0037] Furthermore, in the above technical solution, the air inlet and air outlet of the filter housing are located on opposite sides of the filter housing, and the opening area of ​​the air inlet is smaller than the opening area of ​​the air outlet.

[0038] Furthermore, in the above technical solution, the thickness of the filter screen is less than the thickness of the reinforcing rib, and the height of the reinforcing rib is 3 to 5 times the thickness of the filter screen.

[0039] Furthermore, in the above technical solution, the outer surface of the annular sealing flange is provided with several arc-shaped grooves, which are evenly distributed along the circumference of the annular sealing flange, and the radius of curvature of the arc-shaped grooves is adapted to the radius of curvature of the inner wall surface of the filter housing.

[0040] Furthermore, in the above technical solution, the filter housing is made of stainless steel, and the inner wall surface of the filter housing is provided with an annular positioning groove, and the annular sealing flange is embedded in the annular positioning groove.

[0041] Furthermore, in the above technical solution, the reinforcing rib has a fan-shaped structure, the center of the fan-shaped structure coincides with the geometric center of the filter screen, and the edge of the reinforcing rib is arc-shaped.

[0042] Furthermore, in the above technical solution, the filter screen is woven from metal wire mesh with a mesh size of 0.5mm to 2mm, and the filter screen has a flat structure.

[0043] Furthermore, in the above technical solution, the ratio of the upper base width of the trapezoidal cross-section of the annular sealing flange to the thickness of the filter screen is 2:1 to 3:1, and the ratio of the lower base width to the upper base width of the trapezoidal cross-section is 1.5:1 to 2.5:1.

[0044] The following is a specific embodiment 1 of this utility model: The return air filter assembly of the heat treatment circulation device provided in this embodiment is applied to a continuous heat treatment furnace with a working temperature range of 200℃~600℃. This heat treatment furnace is used for the quenching and tempering of steel parts, and the circulating air volume is 8000m³ / h. The filter shell is welded from 304 stainless steel plate. The shell is cylindrical in shape, with an inner diameter of 800mm, a length of 250mm, and a wall thickness of 3mm. The air inlet is located at one end of the cylindrical shell. The air inlet is a circular opening with a diameter of 600mm, and a flange is welded to the outside of the air inlet for connection with the return air duct. The air outlet is located at the other end of the cylindrical shell. The air outlet is also a circular opening with a diameter of 750mm, and a flange is also welded to the outside of the air outlet for connection with the fan inlet. At a position 150mm away from the air inlet, an annular positioning groove is machined on the inner wall of the shell. The cross-section of the annular positioning groove is rectangular, with a width of 15mm and a depth of 8mm. The annular positioning groove is continuously distributed along the entire circumference of the inner wall of the shell. The filter screen is woven from 304 stainless steel wire with a diameter of 0.8mm, and the mesh size is 1mm × 1mm. The filter screen is a circular flat plate with a diameter of 780mm and a thickness of 2mm. An annular sealing flange, also made of 304 stainless steel, is welded to the edge of the filter screen. The annular sealing flange has a trapezoidal cross-section, with an upper base width of 5mm, a lower base width of 12mm, and a height of 8mm. The length of the annular sealing flange extending circumferentially along the edge of the filter screen is 92% of the filter screen's circumference. A 30mm opening is provided circumferentially to relieve welding stress and thermal expansion stress. Eight arc-shaped grooves are evenly distributed circumferentially on the outer surface of the annular sealing flange. Each arc-shaped groove is 15mm wide, 1.5mm deep, and has a radius of curvature of 400mm, the same as the radius of curvature of the inner wall of the casing. Seven reinforcing ribs are vertically welded to one side of the filter screen. These ribs are made of 304 stainless steel sheet with a thickness of 3mm. Each rib is fan-shaped, with its center coinciding with the geometric center of the filter screen. The radius of the fan is 380mm, and the central angle is 50°. The included angle between two adjacent ribs is 51.4°. The height of each rib is 6mm, and its edges are rounded with a radius of 3mm. One end of each rib is welded to a circular reinforcing plate at the center of the filter screen. This circular reinforcing plate has a diameter of 80mm and a thickness of 3mm. The other end of the rib extends to a position 10mm from the inner edge of the annular sealing flange. During assembly, the annular sealing flange is aligned with the annular positioning groove on the inner wall of the housing and pushed axially until it is fully embedded in the groove. At this point, the trapezoidal lower surface of the annular sealing flange is in close contact with the bottom surface of the positioning groove, and the two inclined surfaces of the trapezoid form an interference fit with the two side walls of the positioning groove. The embedding depth is 7mm.During normal operation of the heat treatment furnace, the return airflow carrying scale and dust enters the air inlet chamber through the air inlet. The airflow pressure is 800Pa to 1200Pa. The airflow impacts the filter screen plate, and the radially distributed reinforcing ribs bear the bending moment and shear force generated by the airflow pressure, transferring the load to the annular sealing flange at the edge. Under the action of the load, the annular sealing flange is pressed into the annular positioning groove. The sealing effect increases with the increase of pressure. The airflow can only pass through the 1mm mesh of the filter screen plate. Particles with a diameter greater than 1mm are effectively intercepted, and the filtration efficiency meets the design requirements. The filtered clean airflow is discharged from the air outlet and enters the fan, completing one cycle.

[0045] The following is another specific embodiment 2 of this utility model: This embodiment 2 is an improvement on embodiment 1, designed for higher temperature conditions, and is applied to a high-temperature annealing furnace with an operating temperature range of 400℃~850℃. The filter housing is made of 310S heat-resistant stainless steel plate, with the wall thickness increased to 4mm to improve high-temperature strength. A high-temperature resistant ceramic fiber sealing layer is added between the annular sealing flange and the housing. The ceramic fiber sealing layer is 1mm thick and fills the arc-shaped groove of the annular sealing flange, further improving the sealing performance and compensating for the difference in thermal expansion of materials at high temperatures. The filter screen is woven from 310S stainless steel wire with a diameter of 1mm, and the mesh size is reduced to 0.8mm, improving the filtration capacity for fine oxide particles. The number of reinforcing ribs is increased to 8, the adjacent included angle is adjusted to 45°, the height of the reinforcing ribs is increased to 8mm, and the thickness is increased to 4mm to cope with the reduction in material strength and greater thermal stress at high temperatures. The improved design exhibits good structural stability and sealing reliability under high-temperature conditions. The filter screen remains flat during long-term high-temperature operation without significant deformation or vibration. The sealing system maintains good airtightness under thermal expansion, effectively preventing the bypassing of high-temperature airflow and ensuring the effect of return air filtration.

[0046] The following is another specific embodiment 3 of this utility model: This embodiment 3 is an optimization based on embodiment 1, targeting the requirements of high air volume and low resistance, and is applied to a large multi-purpose furnace with an operating temperature range of 150℃~400℃ and a circulating air volume of 15000m³ / h. The inner diameter of the filter shell is increased to 1200mm, the length is increased to 300mm, the inlet diameter is increased to 900mm, and the outlet diameter is increased to 1100mm to reduce airflow velocity and flow resistance. The diameter of the filter screen is correspondingly increased to 1180mm, adopting a double-layer composite structure. The first layer is a coarse filter layer with a mesh size of 2mm, and the second layer is a fine filter layer with a mesh size of 1mm. The two filter screens are spaced 10mm apart and supported and fixed by reinforcing ribs. This double-layer structure effectively reduces the flow resistance of a single-layer screen while ensuring filtration effect. The dimensions of the annular sealing flange are enlarged proportionally, with a trapezoidal cross-section having an upper base width of 6mm, a lower base width of 14mm, and a height of 10mm. The number of reinforcing ribs remains at 7, but the fan-shaped radius is increased to 570mm, the height is increased to 10mm, and the thickness remains at 3mm. This optimized solution operates smoothly under high airflow conditions. The dual-layer filtration structure ensures that coarse particles are trapped in the first layer and fine particles are captured in the second layer, avoiding the problem of rapid clogging of single-layer mesh panels, extending the cleaning cycle, and reducing flow resistance by approximately 30% compared to single-layer mesh panels, thus improving the energy efficiency of the circulation system.

[0047] Specifically, the principle of this utility model is as follows: The core of this utility model lies in achieving simultaneous improvement in sealing performance and structural stability through structural optimization. The annular sealing flange adopts a trapezoidal cross-section structure. The upper bottom surface forms a stable connection with the filter screen plate, and the lower bottom surface forms a large-area contact with the inner wall surface of the shell. This gradually changing trapezoidal structure allows the annular sealing flange to evenly transmit pressure to the inner wall surface of the shell when airflow pressure acts on the filter screen plate, forming a self-tightening sealing effect. The greater the airflow pressure, the better the sealing effect. The continuous design of the annular sealing flange along the circumference eliminates the problem of air leakage at the joints that is prone to occur in traditional segmented seals. The arc-shaped groove set on the outer side can adapt to the curved shape of the inner wall surface of the shell and provide a certain elastic deformation space, further enhancing the sealing reliability. The radially distributed reinforcing ribs extend from the geometric center of the filter screen plate to the inner edge of the annular sealing flange, forming a support structure similar to wheel spokes. This structure can effectively transfer the distributed load acting on the filter screen plate to the edge constraint position, avoiding the deflection deformation caused by insufficient support in the middle of the screen plate. The reinforcing ribs are positioned perpendicular to the mesh plate plane, maximizing resistance to vertical airflow pressure. The fan-shaped structure and rounded edges reduce stress concentration and improve structural fatigue strength. The design of the inlet area being smaller than the outlet area allows airflow to enter a larger outlet cavity after passing through the filter mesh plate, reducing flow velocity and pressure recovery, thus minimizing dynamic pressure loss and noise generation at the outlet. The annular positioning groove on the inner wall of the filter housing forms an embedded fit with the annular sealing flange, providing accurate positioning and increasing the sealing contact area and constraint stiffness. This makes the entire filter assembly a highly rigid, well-sealed, and stable integrated structure, enabling long-term reliable operation in the harsh working environment of heat treatment cycle devices.

[0048] The specific operation or use method of this utility model is as follows: When installing the return air filter assembly, first assemble the filter screen plate, annular sealing flange, and reinforcing ribs into one unit. Check whether the trapezoidal structure of the annular sealing flange is complete, whether the arc-shaped groove is clean and free of debris, and whether the reinforcing ribs are perpendicular to the plane of the filter screen plate and evenly distributed. Then, align the assembled filter screen plate assembly with the annular positioning groove of the filter housing and slowly push it in axially. Carefully observe whether the annular sealing flange is smoothly embedded in the positioning groove to avoid jamming or damage to the sealing surface due to misalignment. After the annular sealing flange is fully embedded in the annular positioning groove, press the annular sealing flange circumferentially by hand to ensure that it fits tightly against the inner wall of the housing without any obvious gaps. After installation, connect the air inlet of the filter housing to the return air duct of the heat treatment circulation device, and connect the air outlet to the fan inlet or the next stage treatment unit. Before starting the equipment, check the airtightness of all connections to ensure that there is no air leakage. During normal operation, the return airflow enters the air inlet chamber through the air inlet. Under the pressure of the airflow, the seal between the annular sealing flange and the inner wall of the housing becomes tighter, allowing the airflow to enter the air outlet chamber only through the mesh of the filter plate. Particulate matter and impurities are trapped on the surface of the filter plate. Radially distributed reinforcing ribs withstand the load generated by the airflow pressure, keeping the filter plate flat and stable. The filtered clean airflow exits from the air outlet and enters the next stage of the circulation system. During use, the dust accumulation on the filter plate should be checked regularly. If a large amount of dust is found on the filter plate surface, causing a significant increase in airflow resistance, the filter plate should be cleaned or replaced promptly to ensure the normal operating performance of the filter assembly.

Claims

1. A return air filter assembly for a heat treatment circulation device, comprising a filter housing and a filter screen disposed inside the filter housing, the filter housing having an air inlet and an air outlet, the filter screen dividing the interior of the filter housing into an air inlet chamber and an air outlet chamber, characterized in that, The filter screen plate has an annular sealing flange on its edge, which fits tightly against the inner wall of the filter housing. The length of the annular sealing flange extending circumferentially along the filter screen plate is greater than 85% of the circumference of the filter screen plate edge. The filter screen plate has a reinforcing rib plate in its central area, which is radially distributed. One end of the reinforcing rib plate is connected to the geometric center of the filter screen plate, and the other end of the reinforcing rib plate extends to the inner edge of the annular sealing flange.

2. The return air filter assembly of a heat treatment circulation device according to claim 1, characterized in that, The cross-section of the annular sealing flange is trapezoidal, the upper bottom surface of the trapezoidal structure is connected to the edge of the filter screen, and the lower bottom surface of the trapezoidal structure is in contact with the inner wall surface of the filter housing.

3. The return air filter assembly of a heat treatment circulation device according to claim 2, characterized in that, The number of reinforcing ribs is 6 to 8, the included angle between two adjacent reinforcing ribs is equal, and the reinforcing ribs are arranged perpendicular to the plane of the filter screen.

4. The return air filter assembly of a heat treatment circulation device according to claim 3, characterized in that, The air inlet and air outlet of the filter housing are located on opposite sides of the filter housing, and the opening area of ​​the air inlet is smaller than the opening area of ​​the air outlet.

5. The return air filter assembly of a heat treatment circulation device according to claim 4, characterized in that, The thickness of the filter screen is less than the thickness of the reinforcing rib, and the height of the reinforcing rib is 3 to 5 times the thickness of the filter screen.

6. The return air filter assembly of a heat treatment circulation device according to claim 5, characterized in that, The outer surface of the annular sealing flange is provided with a plurality of arc-shaped grooves, which are evenly distributed along the circumference of the annular sealing flange, and the radius of curvature of the arc-shaped grooves is adapted to the radius of curvature of the inner wall surface of the filter housing.

7. The return air filter assembly of a heat treatment circulation device according to claim 6, characterized in that, The filter housing is made of stainless steel, and the inner wall of the filter housing is provided with an annular positioning groove, and the annular sealing flange is embedded in the annular positioning groove.

8. The return air filter assembly of a heat treatment circulation device according to claim 7, characterized in that, The reinforcing rib has a fan-shaped structure, the center of which coincides with the geometric center of the filter screen, and the edge of the reinforcing rib is arc-shaped.

9. The return air filter assembly of a heat treatment circulation device according to claim 8, characterized in that, The filter screen is woven from metal wire mesh with a mesh size of 0.5mm to 2mm, and the filter screen has a flat plate structure.

10. The return air filter assembly of a heat treatment circulation device according to claim 9, characterized in that, The ratio of the upper base width of the trapezoidal cross-section of the annular sealing flange to the thickness of the filter screen is 2:1 to 3:1, and the ratio of the lower base width to the upper base width of the trapezoidal cross-section is 1.5:1 to 2.5:1.

Images