Air duct guide structure of a heat treatment cycle device

Abstract

The utility model provides a kind of air duct flow guide structure of heat treatment circulating device belongs to metal processing technical field, the air duct flow guide structure of this heat treatment circulating device includes flow guide cylinder and flow guide blade, flow guide cylinder is hollow circular truncated cone structure, the ratio of the major diameter and the minor diameter of flow guide cylinder is 2:1~3:1, flow guide blade is set on the inner wall of flow guide cylinder, flow guide blade is helically distributed along the axial direction of flow guide cylinder, one end of flow guide blade is fixedly connected on the inner wall of flow guide cylinder, the other end of flow guide blade points to the axial line direction of flow guide cylinder but does not contact with axial line, adjacent two pieces of flow guide blade form helical air passage, the included angle of flow guide blade and flow guide cylinder inner wall is 30 °~60 °;The utility model can solve the problem that air distribution is uneven in air duct, leading to the temperature difference of each part of heat treatment workpiece is larger, affect the stability and consistency of heat treatment quality.

Description

Technical Field

[0001] This utility model belongs to the field of metal processing technology, and specifically relates to an air duct guide structure for a heat treatment circulation device. Background Technology

[0002] Heat treatment circulation devices are widely used in the heat treatment of metallic materials. By controlling the furnace temperature and atmosphere, they perform heat treatment operations such as annealing, quenching, and tempering on workpieces to improve their mechanical and performance properties. In these devices, a circulating fan drives the continuous circulation of gas within the furnace, evenly transferring the heat generated by the heating elements to the workpiece and achieving uniform temperature distribution. The duct system, as the channel for gas circulation, has a significant impact on the distribution and circulation efficiency of the airflow. Currently, the commonly used duct guide structures are mainly of two types: straight-cylinder ducts and folded-plate guide plates. Straight-cylinder ducts are simple in structure, but the airflow is prone to forming jets when passing through them. This leads to excessively high airflow velocity in some areas of the furnace while airflow stagnates in others, resulting in uneven temperature distribution. While folded baffles can achieve a certain degree of airflow guidance by changing the airflow direction, eddies and separation are easily generated at the folds, increasing airflow resistance and energy loss. At the same time, the folded structure is prone to deformation or cracking due to thermal stress concentration in high-temperature environments, affecting its service life. With the increasing demands for temperature uniformity in heat treatment processes and the growing urgency for energy conservation and consumption reduction, existing airflow guiding structures are no longer sufficient to meet actual production needs. There is an urgent need to develop a new type of airflow guiding structure that can achieve precise airflow control, reduce energy loss, and improve temperature uniformity. Utility Model Content

[0003] In view of this, the present invention provides a duct flow guide structure for a heat treatment circulation device, which can solve the problem that uneven airflow distribution inside the duct during long-term high-temperature operation of the heat treatment circulation device leads to large temperature differences in different parts of the heat-treated workpiece, affecting the stability and consistency of heat treatment quality. At the same time, the airflow generates significant energy loss and noise when flowing in the duct, reducing the energy utilization efficiency and working environment comfort of the heat treatment circulation device. Most existing duct flow guide structures adopt simple straight cylinder or folded plate designs, lacking the ability to finely control the airflow, making it difficult to meet the high requirements of modern heat treatment processes for temperature uniformity and energy efficiency.

[0004] This utility model is implemented as follows:

[0005] This utility model provides an air duct guide structure for a heat treatment circulation device, comprising a guide cylinder and guide vanes. The guide cylinder is a hollow frustum-shaped structure with a diameter ratio of 2:1 to 3:1 at the large end to the small end. The guide vanes are disposed on the inner wall of the guide cylinder and are spirally distributed along the axial direction of the guide cylinder. One end of the guide vane is fixedly connected to the inner wall of the guide cylinder, and the other end of the guide vane points towards the axis of the guide cylinder but does not contact the axis. A spiral airflow channel is formed between two adjacent guide vanes, and the angle between the guide vane and the inner wall of the guide cylinder is 30° to 60°.

[0006] The technical effects of the air duct guide structure of the heat treatment circulation device provided by this utility model are as follows: By designing the guide cylinder as a frustum-shaped structure and setting spirally distributed guide vanes on its inner wall, the airflow entering the guide cylinder is guided by the guide vanes to form a rotating flow. This rotating flow enables the airflow to obtain a more uniform velocity and pressure distribution inside the guide cylinder. At the same time, the specific angle design between the guide vanes and the inner wall of the guide cylinder can effectively reduce the degree of turbulence when the airflow passes through, reduce energy loss, improve the overall heat exchange efficiency of the heat treatment circulation device, and the frustum-shaped structure can gradually accelerate or decelerate the airflow when it passes through, adapting to the airflow adjustment needs under different working conditions.

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

[0008] The large end of the guide tube is provided with a flange connecting plate, which extends radially outward along the outer circumference of the large end of the guide tube, and fixing holes are evenly distributed on the flange connecting plate.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting a flange connection plate at the large end of the guide cylinder and setting fixing holes on the flange connection plate, a reliable installation connection method is provided for the air duct guide structure. The radial extension design of the flange connection plate can increase the contact area with the air duct system of the heat treatment circulation device, improve the connection strength and sealing performance, and the uniform distribution of fixing holes ensures uniform stress during installation, avoids connection failure caused by local stress concentration, and facilitates on-site installation, maintenance and disassembly, thereby improving the practicality and maintainability of the air duct guide structure.

[0010] Furthermore, the cross-sectional shape of the guide vane is streamlined, and the thickness of the edge of the guide vane near the inner wall of the guide cylinder is greater than the thickness of the edge pointing towards the axis.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by designing the cross-section of the guide vane to be streamlined and making the thickness of the edge near the inner wall of the guide cylinder greater than the thickness of the edge pointing towards the axis, the resistance and noise generated when the airflow passes through the guide vane can be effectively reduced. The streamlined cross-section allows the airflow to flow smoothly along the surface of the guide vane, reducing separation and eddy current generation. The gradient thickness design enhances the strength of the root of the guide vane, enabling it to withstand greater airflow impact without deformation or breakage. At the same time, it reduces the weight of the end of the guide vane and reduces the additional stress on the inner wall of the guide cylinder.

[0012] Furthermore, the helix angle of the guide vanes along the axial direction of the guide cylinder is 15°~45°, and the helix angle gradually increases from the large end to the small end along the guide cylinder.

[0013] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting the helical rise angle of the guide vanes along the axial direction of the guide cylinder and gradually increasing the helical rise angle from the large end to the small end, it is possible to make adaptive adjustments according to the changes in airflow velocity and pressure at different positions of the guide cylinder. The smaller helical rise angle at the large end of the guide cylinder can exert a gentle guiding effect on the initially entering airflow, avoiding energy loss caused by sudden changes in flow direction, while the larger helical rise angle at the small end of the guide cylinder can enhance the rotation effect of the airflow, ensuring that the airflow still maintains a good rotation state at the outlet. This gradual design makes the entire guiding process smoother and more continuous.

[0014] Furthermore, the surface of the guide vanes is provided with micro-convex textures, which are distributed in a wave-like or fish-scale pattern on the windward side of the guide vanes.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting micro-convex textures distributed in a wave-like or fish-scale pattern on the surface of the guide vane, the boundary layer flow characteristics between the airflow and the surface of the guide vane can be changed. The micro-convex textures can form small disturbances on the surface of the guide vane, delay the occurrence of boundary layer separation, and reduce airflow resistance. At the same time, these micro-convex textures can also increase the heat exchange area on the surface of the guide vane, improve the heat exchange efficiency between the guide structure and the airflow, and the wave-like or fish-scale pattern can guide the airflow to flow in a specific direction, further optimize the airflow state, and reduce the noise level.

[0016] Furthermore, a rectifier ring is provided at the small end of the guide tube. The rectifier ring is an annular protrusion structure. The rectifier ring extends radially inward along the inner circumference of the small end of the guide tube. The inner diameter of the rectifier ring is equal to the inner diameter formed by the end of the guide vane pointing towards the axis.

[0017] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting an inwardly radially extending rectifier ring at the small end of the guide tube, the rotating airflow guided by the guide vanes can be rectified a second time. The annular protrusion structure of the rectifier ring can constrain the radial diffusion of the airflow, keeping the airflow relatively concentrated at the outlet, avoiding the airflow from diffusing to the outside of the guide tube and reducing the flow velocity. The design that the inner diameter of the rectifier ring is equal to the inner diameter formed by the end of the guide vanes ensures the continuity of the airflow channel, avoids pressure loss caused by abrupt changes in cross-section, and improves the stability of airflow delivery and the overall performance of the guide structure.

[0018] Furthermore, the number of guide vanes is 3 to 8, and the guide vanes are evenly distributed along the circumferential direction of the inner wall of the guide cylinder, with the circumferential angle between two adjacent guide vanes being equal.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting the number of guide vanes to 3 to 8 and distributing them evenly along the circumference of the inner wall of the guide cylinder, the complexity of the structure and manufacturing cost can be optimized while ensuring the guiding effect. An appropriate number of guide vanes can form an effective spiral airflow channel without causing excessive airflow resistance due to too many vanes. The evenly distributed design ensures that each guide vane bears the same airflow force, avoiding structural vibration and fatigue damage caused by uneven force. The equal circumferential angle between adjacent guide vanes ensures that the flow capacity of each airflow channel is consistent, making the airflow distribution more uniform.

[0020] Furthermore, the guide tube is made of heat-resistant stainless steel, and the guide blades and the guide tube are integrally formed.

[0021] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by using heat-resistant stainless steel to make the guide cylinder and forming an integral structure with the guide blades, it is possible to ensure that the air duct guide structure maintains stable mechanical properties and corrosion resistance under high temperature heat treatment environment. Heat-resistant stainless steel has excellent high temperature strength and oxidation resistance, and can work under high temperature conditions for a long time without material deterioration. The integral structure eliminates the connection gap between the guide blades and the guide cylinder, avoiding loosening or falling off of the connection due to thermal expansion and contraction. At the same time, it improves the strength and rigidity of the overall structure and extends the service life.

[0022] Furthermore, the outer wall surface of the guide tube is provided with heat dissipation ribs, which extend along the axial direction of the guide tube and the height of the heat dissipation ribs gradually decreases from the large end to the small end of the guide tube.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting axially extending heat dissipation ribs on the outer wall surface of the guide tube and gradually reducing the height of the heat dissipation ribs from the large end to the small end, the heat dissipation capacity of the guide tube can be effectively enhanced. The heat dissipation ribs increase the heat exchange area between the guide tube and the external environment, accelerate the dissipation of heat from the guide tube wall, and prevent the guide tube from being affected by excessively high temperature due to long-term exposure to high temperature environment. The gradient change design of the height of the heat dissipation ribs is adapted to the temperature distribution law of the airflow inside the guide tube. Higher heat dissipation ribs are set at the large end where the temperature is higher to enhance heat dissipation, and the height of the heat dissipation ribs is reduced at the small end where the temperature is relatively lower to reduce weight.

[0024] Furthermore, the outer circumferential edge of the flange connection plate is provided with positioning bosses, which are distributed at intervals along the circumferential direction of the flange connection plate. The number of positioning bosses is the same as the number of fixing holes and their positions correspond. The height of the positioning bosses is 1 to 2 times the thickness of the flange connection plate.

[0025] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: By setting positioning bosses with the same number and corresponding positions as the fixing holes on the outer circumferential edge of the flange connecting plate, accurate positioning function can be provided when installing the air duct guide structure. The positioning bosses can cooperate with the corresponding positioning grooves or positioning holes on the air duct system of the heat treatment circulation device to ensure that the installation position of the air duct guide structure is accurate and correct, avoiding uneven airflow distribution or poor sealing caused by installation deviation. The design that the height of the positioning boss is 1 to 2 times the thickness of the flange connecting plate ensures sufficient positioning depth without making the positioning boss too long and causing interference during installation, thus improving the convenience and reliability of installation.

[0026] Compared with existing technologies, the beneficial effects of the air duct guide structure of the heat treatment circulation device provided by this utility model are as follows: By designing an air duct guide structure that combines a frustum-shaped guide cylinder and spirally distributed guide blades, the airflow state inside the air duct of the heat treatment circulation device is fundamentally improved, achieving uniform airflow distribution and efficient delivery. The frustum-shaped guide cylinder allows the airflow speed and pressure to change gradually as it passes through, avoiding energy loss caused by sudden changes. The spiral guide blades provide stable rotational motion to the airflow, enhancing the mixing uniformity of the airflow. The streamlined blade cross-section and surface micro-convex texture design effectively reduce airflow resistance and noise levels, improving energy utilization efficiency. The setting of the rectifier ring and heat dissipation ribs further optimizes the airflow outlet state and the thermal stability of the guide structure. The structural design of the flange connection plate and positioning boss ensures the reliability and convenience of installation. The heat-resistant stainless steel one-piece molding structure ensures long-term stable operation in high-temperature environments. Compared with existing technologies, this utility model can significantly improve the temperature uniformity of heat-treated workpieces, reduce the energy consumption and noise of the heat treatment circulation device, and extend the service life of the air duct system, demonstrating significant technological progress and practical value. 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 A schematic diagram of the air duct guide structure of a heat treatment circulation device;

[0029] Figure 2 A frontal view of the large-end diameter side of the air duct guide structure of a heat treatment circulation device;

[0030] Figure 3 A front view of the small-end diameter side of the air duct guide structure of a heat treatment circulation device;

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

[0032] 10. Flow guide cylinder; 11. Flow guide vanes; 12. Airflow channel; 13. Flange connection plate; 14. Fixing hole; 15. Micro-convex texture; 16. Rectifier ring; 17. Heat dissipation ribs; 18. Positioning boss. 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 Figure 1-3 The image shows an embodiment of the air duct guide structure of a heat treatment circulation device provided by this utility model. In this embodiment, it includes a guide cylinder 10 and guide blades 11. The guide cylinder is a hollow frustum-shaped structure. The ratio of the diameter of the large end to the diameter of the small end of the guide cylinder is 2:1 to 3:1. The guide blades are disposed on the inner wall of the guide cylinder and are spirally distributed along the axial direction of the guide cylinder. One end of the guide blade is fixedly connected to the inner wall of the guide cylinder, and the other end of the guide blade points towards the axis of the guide cylinder but does not contact the axis. A spiral airflow channel 12 is formed between two adjacent guide blades. The angle between the guide blade and the inner wall of the guide cylinder is 30° to 60°.

[0035] In the above technical solution, a flange connection plate 13 is provided at the large end of the guide cylinder. The flange connection plate extends radially outward along the outer circumference of the large end of the guide cylinder, and fixing holes 14 are evenly distributed on the flange connection plate.

[0036] Furthermore, in the above technical solution, the cross-sectional shape of the guide vane is streamlined, and the thickness of the edge of the guide vane near the inner wall of the guide cylinder is greater than the thickness of the edge pointing towards the axis.

[0037] Furthermore, in the above technical solution, the helix angle of the guide vane along the axial direction of the guide cylinder is 15°~45°, and the helix angle gradually increases from the large end to the small end along the guide cylinder.

[0038] Furthermore, in the above technical solution, the surface of the guide vane is provided with micro-protrusion texture 15, which is distributed in a wave-like or fish-scale-like pattern on the windward side of the guide vane.

[0039] Furthermore, in the above technical solution, a rectifier ring 16 is provided at the small end of the guide tube. The rectifier ring is an annular protrusion structure. The rectifier ring extends radially inward along the inner circumference of the small end of the guide tube. The inner diameter of the rectifier ring is equal to the inner diameter formed by the end of the guide vane pointing towards the axis.

[0040] Furthermore, in the above technical solution, the number of guide vanes is 3 to 8, the guide vanes are evenly distributed along the circumferential direction of the inner wall of the guide cylinder, and the circumferential included angle between two adjacent guide vanes is equal.

[0041] Furthermore, in the above technical solution, the guide cylinder is made of heat-resistant stainless steel, and the guide blades and the guide cylinder are integrally formed.

[0042] Furthermore, in the above technical solution, the outer wall surface of the guide cylinder is provided with heat dissipation ribs 17, which extend along the axial direction of the guide cylinder and the height of the heat dissipation ribs gradually decreases from the large end to the small end of the guide cylinder.

[0043] Furthermore, in the above technical solution, a positioning boss 18 is provided on the outer circumferential edge of the flange connecting plate. The positioning bosses are distributed at intervals along the circumferential direction of the flange connecting plate. The number of positioning bosses is the same as the number of fixing holes and their positions correspond. The height of the positioning bosses is 1 to 2 times the thickness of the flange connecting plate.

[0044] The specific method of using this utility model is as follows: First, according to the installation position and size requirements of the air duct system of the heat treatment circulation device, select an air duct guide structure of appropriate specifications. Align the positioning boss on the flange connecting plate of the air duct guide structure with the corresponding positioning groove on the air duct system of the heat treatment circulation device, ensuring that the axis of the guide cylinder is consistent with the airflow direction of the air duct. Then, use bolts to firmly fix the air duct guide structure to the air duct system through the fixing holes on the flange connecting plate. When tightening the bolts, tighten them gradually in a diagonal sequence to ensure that the contact surface between the flange connecting plate and the air duct system is evenly stressed, achieving a good sealing effect. After installation, start the heat treatment... The circulating fan of the air circulation device drives the airflow to enter from the large end of the guide cylinder. As it passes through the guide cylinder, it is guided by the spiral guide vanes to form a rotating flow. After being constrained by the rectifier ring, the rotating airflow exits from the small end of the guide cylinder and enters the heat treatment furnace to heat the workpiece. During use, the installation status of the air duct guide structure should be checked regularly to confirm whether the bolt connections are loose and whether the guide cylinder and guide vanes are deformed or damaged. If any abnormalities are found, maintenance or replacement should be carried out in time. After long-term use, dust or oxides may accumulate on the surface of the guide vanes, so they should be cleaned regularly to maintain a good guiding effect.

[0045] The following is a specific embodiment 1 of this utility model: The air duct guide structure provided in this embodiment is used in the circulating air duct system of a continuous heat treatment furnace. The guide cylinder is made of 304 heat-resistant stainless steel sheet by stamping. The guide cylinder is generally truncated cone-shaped, with a large end diameter of 600mm and a small end diameter of 240mm. The diameter ratio of the large end to the small end is 2.5:1. The axial length of the guide cylinder is 800mm, and the wall thickness is 3mm. There are a total of 6 guide blades, which are evenly distributed along the circumferential direction of the inner wall of the guide cylinder. The circumferential angle between two adjacent guide blades is 60°. The guide blades are made of the same 304 heat-resistant stainless steel material as the guide cylinder and are formed by stamping. The cylinder body is formed as a single molded structure. Each guide vane is spirally distributed along the axial direction of the guide cylinder body. The spiral angle is 20° at the large end of the guide cylinder body and gradually increases to 40° at the small end along the axial direction. The angle between the guide vane and the inner wall of the guide cylinder body is 45°. One end of the guide vane is completely welded and fixed to the inner wall of the guide cylinder body, and the other end points towards the axis of the guide cylinder body. The closest distance to the axis is 80mm. The cross-section of the guide vane is streamlined. The thickness of the edge near the inner wall of the guide cylinder body is 5mm, and the thickness of the edge pointing towards the axis is 2mm. A wave-shaped micro-convex texture is formed on the windward surface of the guide vane through machining. The wavelength of the wave is 15mm and the wave height is 0.An 8mm thick flange is welded to the outer circumference of the large end of the guide tube. The flange is made of 10mm thick 304 stainless steel plate and extends radially outward by 60mm along the outer circumference of the large end of the guide tube. Twelve 12mm diameter fixing holes are evenly distributed on the flange, with a circle diameter of 700mm. A positioning boss is welded to the outer circumference edge of the flange corresponding to each fixing hole. The positioning boss is cylindrical with a diameter of 20mm and a height of [missing information]. The diameter is 15mm. A rectifier ring is welded to the inner circumference of the small end of the guide tube. The rectifier ring is made of 304 stainless steel ring plate with a width of 20mm and a thickness of 3mm. The rectifier ring extends radially inward along the inner circumference of the small end of the guide tube. The inner diameter of the rectifier ring is 160mm, which is consistent with the inner diameter of the circular channel formed by the end of the guide vane pointing to the axis. 24 heat dissipation ribs are uniformly welded axially on the outer wall surface of the guide tube. The heat dissipation ribs are made of 304 stainless steel plate with a thickness of 2mm. The height of the guide tube at its large end is 30mm, gradually decreasing axially to 12mm at the small end. The length of the heat dissipation ribs is the same as the axial length of the guide tube. In this embodiment, the air duct guide structure is installed in the circulating air duct of a continuous heat treatment furnace. The circulating fan drives the gas inside the furnace to circulate at a flow rate of 12000m³ / h. The airflow enters from the large end of the guide tube and, as it passes through the guide tube, is guided by the spiral guide vanes to form a stable rotating flow. After being constrained by the rectifier ring, the rotating airflow exits from the small end and enters the furnace chamber. Due to the rotation of the airflow, the temperature uniformity of various parts of the furnace chamber is significantly improved, and the temperature difference between different parts of the heat-treated workpiece is controlled within ±5℃. The pressure loss of the airflow passing through the guide structure is 180 Pa, the noise level is 72 dB, and the outer wall temperature of the guide tube is maintained at around 350℃, which is lower than the allowable operating temperature of 304 stainless steel. After six months of continuous operation testing, the air duct guide structure did not exhibit any deformation, cracking, or loosening of connections, demonstrating good structural stability and reliability.

[0046] The following is another specific embodiment 2 of this utility model: This embodiment 2 is based on embodiment 1, but the micro-protrusion texture on the surface of the guide vane is changed from a wave shape to a fish scale shape. The fish scale micro-protrusion texture is formed on the windward side of the guide vane by laser surface treatment. Each fish scale protrusion has a diameter of 8 mm and a height of 0.6 mm. The overlap between adjacent fish scale protrusions is 3 mm. The fish scale protrusions are arranged at a certain angle along the surface of the guide vane, and the tilting direction is consistent with the flow direction of the airflow. This fish scale micro-protrusion texture can more effectively disturb the boundary layer and delay flow separation. Compared with the wave shape texture of embodiment 1, the fish scale texture reduces the pressure loss of the airflow when passing through the guide structure to 165 Pa and the noise level to 68 dB. At the same time, since the fish scale texture increases the heat exchange area on the surface of the guide vane, the outer wall temperature of the guide cylinder is further reduced to 330℃, which improves the thermal stability and service life of the structure. The processing precision requirements of the fish scale micro-protrusion texture are high, but it can obtain better aerodynamic performance and heat exchange performance, and is suitable for applications with higher requirements for heat treatment quality.

[0047] The following is another specific embodiment 3 of this utility model: This embodiment 3 is based on embodiment 1, in which a ceramic coating is applied to the surface of the guide cylinder and the guide blades. The ceramic coating is made of alumina ceramic material and is uniformly sprayed onto the inner and outer surfaces of the guide cylinder and the surface of the guide blades through a plasma spraying process. The coating thickness is 0.3mm~0.5mm. The ceramic coating has excellent high temperature resistance and oxidation resistance, and can work stably for a long time in high temperature environments above 800℃. The surface of the ceramic coating is smooth, which can further reduce the frictional resistance when the airflow passes through. At the same time, the low thermal conductivity of the ceramic material can reduce the heat loss of the guide cylinder to the external environment and improve the thermal efficiency of the heat treatment circulation device. The air duct guide structure after applying the ceramic coating can be applied to higher temperature heat treatment processes, and the working temperature range is extended from 800℃ in embodiment 1 to 1000℃. The ceramic coating can also protect the base metal from high temperature oxidation and corrosion, significantly extending the service life of the air duct guide structure. In high temperature heat treatment applications, the service life of the air duct guide structure with ceramic coating is extended by more than 50% compared with the structure without coating.

[0048] Specifically, the principle of this invention is as follows: Fine control of airflow is achieved through the synergistic effect of a frustum-shaped guide cylinder and spiral guide vanes. When airflow enters from the large end of the guide cylinder, the converging channel of the frustum gradually increases the airflow velocity. According to Bernoulli's equation, as the airflow velocity increases, the pressure gradually decreases. This gradual change in velocity and pressure avoids energy loss caused by sudden changes in cross-section. The spirally distributed guide vanes apply tangential force to the passing airflow, allowing the airflow to acquire a circumferential velocity component while flowing axially, forming a spiral rotating flow. This rotating flow effectively enhances the mixing of airflow and eliminates potential temperature inhomogeneities. The specific angle design between the guide vanes and the inner wall of the guide cylinder ensures smooth airflow along the vane surface, reducing flow separation and vortex generation, resulting in a streamlined shape. The blade cross-section further reduces airflow resistance, and the micro-convex texture on the surface delays separation by disturbing the boundary layer, improving airflow efficiency. The design of the spiral helix angle gradually increasing from the large end to the small end enhances the guiding strength along the flow path, ensuring that the airflow maintains a good rotational state at the outlet. The rectifier ring radially constrains the rotating airflow, preventing it from diffusing outward and maintaining its concentration and stability. The heat dissipation ribs on the outer wall of the guide tube reduce the temperature of the guide tube by increasing the heat exchange area, preventing material performance degradation due to excessive temperature. The heat-resistant stainless steel one-piece molding structure ensures structural stability in high-temperature environments. Through the organic combination of the above-mentioned technical features, this utility model achieves efficient control of airflow in the duct of the heat treatment circulation device, fundamentally solving the technical problems of uneven airflow distribution and high energy loss.

Claims

1. A duct flow guiding structure for a heat treatment circulation device, characterized in that, It includes a guide tube and guide vanes. The guide tube is a hollow frustum-shaped structure with a diameter ratio of 2:1 to 3:1 at the large end to the small end. The guide vanes are set on the inner wall of the guide tube and are spirally distributed along the axial direction of the guide tube. One end of the guide vane is fixedly connected to the inner wall of the guide tube, and the other end of the guide vane points towards the axis of the guide tube but does not contact the axis. A spiral airflow channel is formed between two adjacent guide vanes. The angle between the guide vane and the inner wall of the guide tube is 30° to 60°.

2. The air duct guiding structure of a heat treatment circulation device according to claim 1, characterized in that, The large end of the guide tube is provided with a flange connecting plate, which extends radially outward along the outer circumference of the large end of the guide tube, and fixing holes are evenly distributed on the flange connecting plate.

3. The air duct guiding structure of a heat treatment circulation device according to claim 2, characterized in that, The cross-sectional shape of the guide vane is streamlined, and the thickness of the edge of the guide vane near the inner wall of the guide cylinder is greater than the thickness of the edge pointing towards the axis.

4. The air duct guiding structure of a heat treatment circulation device according to claim 3, characterized in that, The helix angle of the guide vanes along the axial direction of the guide tube is 15°~45°, and the helix angle gradually increases from the large end to the small end along the guide tube.

5. The air duct guiding structure of a heat treatment circulation device according to claim 4, characterized in that, The surface of the guide vanes is provided with micro-convex textures, which are distributed in a wave-like or fish-scale pattern on the windward side of the guide vanes.

6. The air duct guiding structure of a heat treatment circulation device according to claim 5, characterized in that, The small end of the guide tube is equipped with a rectifier ring, which is an annular protrusion structure. The rectifier ring extends radially inward along the inner circumference of the small end of the guide tube, and the inner diameter of the rectifier ring is equal to the inner diameter formed by the end of the guide vane pointing towards the axis.

7. The air duct guiding structure of a heat treatment circulation device according to claim 6, characterized in that, The number of guide vanes is 3 to 8. The guide vanes are evenly distributed along the circumference of the inner wall of the guide cylinder, and the circumferential angle between two adjacent guide vanes is equal.

8. The air duct guiding structure of a heat treatment circulation device according to claim 7, characterized in that, The guide tube is made of heat-resistant stainless steel, and the guide blades and the guide tube are integrally formed.

9. The air duct guiding structure of a heat treatment circulation device according to claim 8, characterized in that, The outer wall surface of the flow guide cylinder is provided with heat dissipation ribs, which extend along the axial direction of the flow guide cylinder and the height of the heat dissipation ribs gradually decreases from the large end to the small end of the flow guide cylinder.

10. The air duct guiding structure of a heat treatment circulation device according to claim 9, characterized in that, The outer circumferential edge of the flange connection plate is provided with positioning bosses. The positioning bosses are distributed at intervals along the circumferential direction of the flange connection plate. The number of positioning bosses is the same as the number of fixing holes and their positions correspond. The height of the positioning bosses is 1 to 2 times the thickness of the flange connection plate.

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