A multi-stage slow cooling assembly of a heat treatment cooling device

Abstract

The utility model provides a kind of multistage slow cooling assembly of heat treatment cooling device belongs to heat treatment cooling device technical field, the multistage slow cooling assembly of this heat treatment cooling device includes slow cooling cavity, the flow guide cylinder being arranged in slow cooling cavity inside, spiral blade being fixed in the inner wall of flow guide cylinder and the central tube being through the axis of flow guide cylinder, the spiral blade is formed multiple cooling subareas along flow guide cylinder axial distribution, the pitch of each cooling subarea spiral blade gradually increases along air flow direction, the outer wall surface of the central tube is opened with multiple rows of heat dissipation holes along the axial direction, the aperture of the heat dissipation hole is ladder type increasing from the air inlet end of flow guide cylinder to air outlet end, annular passage is formed between the inner wall surface of flow guide cylinder and the outer edge of spiral blade;It can solve the problem that existing cooling device cannot carry out differentiated cooling control to different temperature intervals according to workpiece material and heat treatment process requirements, resulting in the problem that workpiece generates internal stress concentration in cooling process due to excessive temperature gradient.

Description

Technical Field

[0001] This utility model belongs to the technical field of heat treatment cooling devices, and more specifically, it relates to a multi-stage slow cooling component of a heat treatment cooling device. Background Technology

[0002] In modern industrial production, heat treatment is widely used for strengthening metal parts. It alters the internal structure of materials through heating and cooling processes to obtain desired mechanical properties. The cooling process has a decisive impact on the final product quality. Currently, commonly used industrial cooling methods include water cooling, oil cooling, and air cooling. However, these methods all have limitations in practical applications. While water and oil cooling offer fast cooling rates, their excessively rapid cooling can easily lead to significant internal stress in the workpiece and even quenching cracks, especially for workpieces with complex shapes or large differences in wall thickness, which are more prone to deformation. Traditional air cooling, while providing gentler cooling, often employs simple direct-flow or circulating cooling structures. The cooling airflow path within the cooling chamber is singular and unevenly distributed, resulting in significant differences in cooling rates across different parts of the workpiece surface. This makes it impossible to meet the requirements for precise control of the cooling process. To address this issue, some companies have adopted segmented cooling equipment, which controls the cooling intensity by setting up multiple independent cooling zones. However, this approach requires a complex airflow control system and multiple sets of cooling equipment, increasing equipment investment and floor space. Furthermore, temperature fluctuations are unavoidable as the workpiece is transferred from one cooling zone to another, affecting the continuity and stability of the cooling curve. Therefore, there is an urgent need for a cooling device component with a simple and reliable structure that can achieve multi-stage slow cooling. Utility Model Content

[0003] In view of this, the present invention provides a multi-stage slow cooling component for a heat treatment cooling device, which can solve the problem that existing heat treatment cooling devices often use a single cooling rate when rapidly cooling workpieces. This method cannot differentiate cooling control for different temperature ranges according to the workpiece material and heat treatment process requirements, resulting in internal stress concentration in the workpiece due to excessive temperature gradient during cooling, which in turn leads to quality problems such as workpiece deformation and cracking. At the same time, it can also solve the problem that a single cooling path causes uneven distribution of cooling medium, resulting in large differences in cooling rate in different parts of the workpiece surface, which affects the consistency of the microstructure and properties of the workpiece after heat treatment and the product qualification rate.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a multi-stage slow cooling component for a heat treatment cooling device, used for graded cooling of heat-treated workpieces. It includes a slow cooling chamber, a guide tube disposed inside the slow cooling chamber, spiral blades fixed to the inner wall of the guide tube, and a central tube penetrating the axis of the guide tube. The spiral blades are distributed along the axial direction of the guide tube to form multiple cooling zones. The pitch of the spiral blades in each cooling zone increases progressively along the airflow direction. The outer wall of the central tube has multiple rows of heat dissipation holes along the axial direction. The diameter of the heat dissipation holes increases in a stepped manner from the air inlet to the air outlet of the guide tube. An annular channel is formed between the inner wall of the guide tube and the outer edge of the spiral blades. The angle between the blade surface of the spiral blades and the axis of the guide tube is 35° to 55°. The inner wall of the slow cooling chamber is provided with several sets of boss structures, which are evenly distributed along the circumference of the slow cooling chamber for radial positioning and support of the guide tube.

[0006] The technical effects of the multi-stage slow cooling component of the heat treatment cooling device provided by this utility model are as follows: By using a structural design in which multiple cooling zones are formed by the distribution of spiral blades along the axial direction of the guide tube and the pitch increases step by step, the residence time and flow rate of the cooling airflow in different zones can be precisely controlled, realizing a gradient decrease in workpiece temperature; the stepped increase in the diameter of the heat dissipation holes on the outer wall of the central tube, combined with the annular channel formed by the spiral blades, makes the distribution of the cooling medium in each zone more uniform, effectively avoiding stress concentration and deformation problems caused by excessive local cooling speed of the workpiece; at the same time, the radial positioning support of the boss structure for the guide tube ensures the stability of the overall structure in a high-temperature environment.

[0007] Based on the above technical solution, the multi-stage slow cooling component of the heat treatment cooling device of this utility model can be further improved as follows:

[0008] The spiral blades form a transition section at the junction of two adjacent cooling zones, and the thickness of the spiral blades in the transition section is greater than the thickness of the spiral blades at other locations within the same cooling zone.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: setting a transition section at the junction of two adjacent cooling zones and increasing the thickness of the spiral blades at that point can effectively alleviate the eddy and turbulent phenomena generated when the cooling airflow alternates between different pitch regions, so that the airflow maintains a stable flow state during the zone transition, avoiding the problem of uneven cooling caused by sudden changes in airflow. At the same time, the thickened spiral blades improve the structural strength of the transition section and extend the service life of the components under high-temperature alternating stress.

[0010] Furthermore, the central tube is provided with reinforcing ribs along the axial direction. The reinforcing ribs are distributed in a spiral shape on the outer wall surface of the central tube, and the spiral direction of the reinforcing ribs is opposite to that of the spiral blades.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the spiral reinforcing ribs set on the outer wall of the central tube form a spiral direction opposite to that of the spiral blades, generating a flow field effect of mutual interference when the cooling airflow passes through, causing the airflow to form a complex three-dimensional flow path, which enhances the heat exchange efficiency between the airflow and the surface of the central tube and the workpiece. At the same time, the reinforcing ribs themselves also increase the bending stiffness and torsional strength of the central tube, preventing the central tube from bending and deforming under long-term high-temperature working conditions.

[0012] Furthermore, the cross-section of the guide tube is polygonal, and each side of the polygonal structure is connected to the adjacent side by an arc transition surface. The radius of curvature of the arc transition surface is less than 1 / 10 of the equivalent circle diameter of the guide tube.

[0013] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the guide tube adopts a polygonal cross-section structure and connects adjacent sides with a circular arc transition surface. Compared with the traditional circular cross-section, the polygonal structure increases the degree of airflow turbulence and the opportunity for contact with the tube wall, thereby improving the heat exchange efficiency. The circular arc transition surface with a small radius of curvature reduces the separation phenomenon of airflow at the corners and reduces the flow resistance. At the same time, the polygonal structure also facilitates the installation of additional cooling or heating devices on the outer wall of the guide tube, thereby improving the functional expandability of the component.

[0014] Furthermore, the spiral blade has several ventilation grooves on its blade surface, the ventilation grooves extend along the radial direction of the spiral blade, and the width of the ventilation grooves gradually increases from the inner edge to the outer edge of the spiral blade.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the radial ventilation grooves opened on the surface of the spiral blades provide additional lateral flow channels for the cooling airflow, allowing some airflow to pass through the spiral blades directly to the adjacent spiral channels, breaking the limitation that the airflow only flows in one direction along the spiral path, and forming a three-dimensional cross cooling network; the design of the ventilation groove width increasing from the inside to the outside adapts to the characteristic of the airflow pressure decreasing in the radial direction, ensuring that the air permeability at each radial position is relatively balanced, and further optimizing the uniformity of the overall cooling effect.

[0016] Furthermore, the air inlet end of the slow cooling cavity is provided with a diffusion cone section, the cone angle of the diffusion cone section is 15~25°, and the inner wall surface of the diffusion cone section is provided with guide ribs, which are distributed radially.

[0017] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the diffusion cone section at the air inlet of the slow cooling cavity allows the incoming high-speed cooling airflow to be fully diffused and decelerated, avoiding local overcooling caused by the airflow directly impacting the inlet of the guide tube. The reasonable setting of the cone angle ensures the stability of airflow diffusion. The radial guide ribs on the inner wall of the diffusion cone section evenly distribute the airflow to all directions around the guide tube, eliminating the circumferential temperature difference caused by uneven air intake, and creating ideal initial conditions for subsequent spiral staged cooling.

[0018] Furthermore, the gap between the outer edge of the spiral blade and the inner wall of the guide tube is less than 1 / 5 of the height of the spiral blade in the radial direction, and the gap remains constant along the axial direction of the guide tube.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the gap distance between the outer edge of the spiral blade and the inner wall of the guide tube is less than 1 / 5 of the radial height of the blade, which ensures that the blade can effectively guide the airflow to form a stable spiral flow, and avoids the problems of airflow blockage and excessive pressure loss caused by the complete sealing of the blade and the tube wall; the design of keeping the gap distance constant along the axial direction ensures that the leakage flow of each cooling zone is consistent, and the cooling effect between zones will not be unbalanced due to the gap change, thus improving the controllability and repeatability of the multi-stage slow cooling process.

[0020] Furthermore, the heat dissipation holes of the central tube are arranged in a quincunx pattern, and the ratio of the axial spacing to the circumferential spacing between adjacent heat dissipation holes is 3:2. The hole walls of the heat dissipation holes have a chamfered structure.

[0021] The beneficial effects of the above-mentioned improvement scheme are as follows: the heat dissipation holes of the central tube are arranged in a quincunx pattern and the axial and circumferential spacing between adjacent holes are maintained in a specific ratio, so that the heat dissipation holes are evenly distributed in space while having a staggered arrangement. This arrangement avoids the phenomenon that the cooling medium is concentrated in some axial or circumferential positions while insufficient in other positions, thus achieving a high degree of uniformity of heat dissipation on the surface of the central tube; the chamfered structure of the heat dissipation hole wall reduces the local resistance and noise when the airflow passes through the hole opening, and improves the spraying efficiency of the cooling medium.

[0022] Furthermore, the guide tube is made of heat-resistant stainless steel, and the spiral blades are fixed to the inner wall of the guide tube by argon arc welding, and the welded joint has a continuous weld structure.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the guide tube is made of heat-resistant stainless steel, which ensures the corrosion resistance and mechanical strength of the component in the high-temperature working environment. The continuous weld structure formed by fixing the spiral blades by argon arc welding enables a reliable metallurgical bond between the blades and the tube. The welded joint can withstand the thermal stress under high temperature conditions without cracking or falling off. At the same time, the continuous weld avoids stress concentration points caused by intermittent welding, which significantly improves the overall reliability and durability of the component and meets the needs of long-term continuous industrial production.

[0024] Furthermore, the annular space formed between the slow cooling cavity and the guide tube is filled with ceramic fiber insulation material. The thickness of the ceramic fiber insulation material is evenly distributed along the axial direction of the slow cooling cavity, and the top surface of the boss structure forms a point contact support with the outer wall surface of the guide tube.

[0025] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the annular space between the slow cooling cavity and the guide tube is filled with ceramic fiber insulation material, which effectively reduces the loss of heat to the external environment and improves the energy utilization efficiency of the cooling process. At the same time, the insulation layer also plays a role in buffering thermal shock and protecting the outer slow cooling cavity from the direct impact of the internal high temperature. The point contact support method formed by the boss structure and the outer wall of the guide tube ensures the radial positioning of the guide tube while minimizing the thermal bridge effect and preventing the support point from becoming a channel for rapid heat conduction. Combined with the uniformly distributed thickness of the insulation material, the overall system achieves a unity of excellent thermal insulation performance and structural stability.

[0026] Compared with existing technologies, the multi-stage slow cooling component of the heat treatment cooling device provided by this utility model has the following advantages: This utility model, through its structural design of spiral blades distributed axially along the guide tube to form multiple cooling zones with progressively increasing pitch in each zone, achieves precise control of the residence time and flow rate of the cooling airflow in different temperature ranges. This allows the workpiece temperature to decrease smoothly according to a preset curve rather than being suddenly cooled, effectively eliminating internal stress caused by excessive temperature gradients and solving the problems of workpiece deformation and cracking. The stepped increase in the diameter of the heat dissipation holes on the outer wall of the central tube, combined with the annular channel formed by the spiral blades, ensures that the cooling medium is evenly distributed in each zone and fully participates in heat exchange, eliminating single-stage cooling... The system eliminates the phenomenon of insufficient or excessive cooling caused by the airflow path; the venting grooves on the spiral blades and the spiral reinforcing ribs on the central tube further promote the three-dimensional flow of airflow, significantly improving cooling uniformity; the polygonal cross-section structure of the guide tube and the flow guiding design of the diffuser cone section optimize the airflow state from the inlet end, laying a good foundation for subsequent staged cooling; the entire component ensures the reliability of long-term high-temperature operation through heat-resistant stainless steel materials and continuous welding process, and achieves excellent thermal insulation performance through ceramic fiber insulation and point contact support. Compared with existing technologies, it not only significantly improves the quality stability and yield of heat-treated workpieces, but also reduces energy consumption and extends the service life of equipment, which has important industrial application 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 structure of a multi-stage slow cooling component in a heat treatment cooling device;

[0029] Figure 2 This is a schematic diagram of the central tube structure;

[0030] The attached diagram lists the components represented by each number as follows:

[0031] 10. Slow-cooling chamber; 20. Flow guide tube; 30. Spiral blades; 40. Central tube; 41. Heat dissipation holes. Detailed Implementation

[0032] 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.

[0033] like Figure 1-2 The diagram shows a multi-stage slow cooling assembly of a heat treatment cooling device provided by this utility model. The assembly, used for staged cooling of heat-treated workpieces, includes a slow cooling chamber 10, a guide tube 20 disposed inside the slow cooling chamber, spiral blades 30 fixed to the inner wall of the guide tube, and a central tube 40 penetrating the axis of the guide tube. The spiral blades are distributed along the axial direction of the guide tube to form multiple cooling zones. The pitch of the spiral blades in each cooling zone increases progressively along the airflow direction. Multiple rows of heat dissipation holes 41 are opened along the axial direction on the outer wall of the central tube. The diameter of the heat dissipation holes increases in a stepped manner from the air inlet end to the air outlet end of the guide tube. An annular channel is formed between the inner wall of the guide tube and the outer edge of the spiral blades. The angle between the blade surface of the spiral blades and the axis of the guide tube is 35° to 55°. Several sets of boss structures are provided on the inner wall of the slow cooling chamber, evenly distributed along the circumference of the slow cooling chamber, for radial positioning and support of the guide tube.

[0034] In the above technical solution, the spiral blades form a transition section at the junction of two adjacent cooling zones, and the thickness of the spiral blades in the transition section is greater than the thickness of the spiral blades at other locations within the same cooling zone.

[0035] Furthermore, in the above technical solution, the central tube is provided with reinforcing ribs along the axial direction. The reinforcing ribs are distributed in a spiral shape on the outer wall surface of the central tube, and the spiral direction of the reinforcing ribs is opposite to the spiral direction of the spiral blades.

[0036] Furthermore, in the above technical solution, the cross-section of the guide tube is a polygonal structure, and each side of the polygonal structure is connected to the adjacent side by a circular arc transition surface. The radius of curvature of the circular arc transition surface is less than 1 / 10 of the equivalent circle diameter of the guide tube.

[0037] Furthermore, in the above technical solution, a number of air-permeable grooves are formed on the surface of the helical blade. The air-permeable grooves extend along the radial direction of the helical blade, and the width of the air-permeable grooves gradually increases from the inner edge to the outer edge of the helical blade.

[0038] Furthermore, in the above technical solution, the air inlet end of the slow cooling cavity is provided with a diffusion cone section, the cone angle of the diffusion cone section is 15~25°, and the inner wall surface of the diffusion cone section is provided with guide ribs, which are distributed radially.

[0039] Furthermore, in the above technical solution, the gap distance between the outer edge of the spiral blade and the inner wall of the guide tube is less than 1 / 5 of the height of the spiral blade in the radial direction, and the gap distance remains constant along the axial direction of the guide tube.

[0040] Furthermore, in the above technical solution, the heat dissipation holes of the central tube are arranged in a quincunx pattern, the ratio of the axial spacing to the circumferential spacing between adjacent heat dissipation holes is 3:2, and the hole walls of the heat dissipation holes have a chamfered structure.

[0041] Furthermore, in the above technical solution, the guide tube is made of heat-resistant stainless steel, and the spiral blades are fixed to the inner wall of the guide tube by argon arc welding, with the welded joint having a continuous weld structure.

[0042] Furthermore, in the above technical solution, the annular space formed between the slow cooling cavity and the guide tube is filled with ceramic fiber insulation material. The thickness of the ceramic fiber insulation material is evenly distributed along the axial direction of the slow cooling cavity, and the top surface of the boss structure forms a point contact support with the outer wall surface of the guide tube.

[0043] The following is a specific embodiment 1 of this utility model: In this embodiment, the slow cooling cavity is made of 304 stainless steel sheet by a plate rolling and welding process. The cavity has a cylindrical structure with an outer diameter of 800mm, a wall thickness of 8mm, and a total length of 2400mm. The air inlet end of the slow cooling cavity is welded with a diffuser cone section, which is 300mm long and has a cone angle of 20°. Eight guide ribs are evenly welded to the inner wall of the diffuser cone section, each guide rib being 30mm wide and 5mm thick, and distributed radially. The guide tube is also made of 304 stainless steel sheet, and the cross-section of the guide tube is a regular octagonal structure with an inscribed circle diameter of 600mm. Adjacent sides are transitioned by an arc surface with a radius of 50mm. The guide tube has a wall thickness of 6mm and a total length of 2400mm. The guide tube is 2000mm in diameter, and spiral blades are fixed to the inner wall of the guide tube. The spiral blades are made of 4mm thick 304 stainless steel strips and are continuously welded to the inner wall of the guide tube by argon arc welding. The spiral blades are divided into 4 cooling zones along the axial direction of the guide tube. The first zone is 400mm long with a pitch of 200mm, the second zone is 500mm long with a pitch of 280mm, the third zone is 600mm long with a pitch of 380mm, and the fourth zone is 500mm long with a pitch of 500mm. The thickness of the spiral blades at the junction of adjacent zones increases to 7mm to form a transition section. Each transition section is 100mm long. The radial height of the spiral blades is 80mm, and the angle between the blade surface and the axis of the guide tube is 45°. The outer edge of the spiral blades is perpendicular to the guide tube axis. A uniform gap of 15mm is maintained between the inner walls of the cylinder. A ventilation groove is formed radially every 120mm on the surface of the helical blades. The groove is 8mm wide at the inner edge and 20mm wide and 2mm deep at the outer edge. The central tube is made of seamless 310S stainless steel with an outer diameter of 200mm and a wall thickness of 6mm, and a length of 2200mm. Four spiral reinforcing ribs are welded axially to the outer wall of the central tube. The ribs are 25mm wide, 6mm thick, and have a pitch of 600mm, with the spiral direction opposite to that of the helical blades. The outer wall of the central tube is divided into four axial sections with heat dissipation holes. The first section corresponds to the first cooling zone with a 12mm diameter heat dissipation hole; the second section corresponds to the second cooling zone with a 18mm diameter heat dissipation hole; the third section… The diameter of the heat dissipation holes corresponding to the third cooling zone is 25mm, and the diameter of the heat dissipation holes corresponding to the fourth cooling zone in the fourth section is 35mm. The heat dissipation holes are arranged in a quincunx pattern with an axial spacing of 90mm and a circumferential spacing of 60mm between adjacent holes. The openings of the heat dissipation holes are machined with a 45° chamfer to a depth of 2mm. A set of boss structures is welded at 45° intervals along the circumference of the inner wall of the slow cooling chamber, for a total of 8 sets. Each set of bosses is set at 400mm intervals along the axial direction, for a total of 5. The bosses are semi-cylindrical with a height of 40mm and a width of 50mm. The top surface of the bosses is precision machined to form point contact with the outer wall of the guide tube. The annular space between the slow cooling chamber and the guide tube is filled with 1260 type ceramic fiber felt with a thickness of 95mm. The bulk density of the ceramic fiber felt is 128kg per cubic meter.In operation, a cylindrical steel workpiece with a diameter of 180mm and a length of 1800mm is suspended on a suspension rod passing through the central tube. The initial workpiece temperature is 850℃. Room temperature compressed air at a pressure of 0.15MPa and a flow rate of 300 cubic meters per hour is introduced into the inlet. After passing through the diffuser cone, the cooling gas enters the guide tube evenly, forming a stable spiral flow under the guidance of the spiral blades. Simultaneously, some gas directly impacts the workpiece surface through the heat dissipation holes in the central tube. The workpiece temperature drops from 850℃ to 650℃ in the first cooling zone, to 480℃ in the second zone, to 320℃ in the third zone, and to 180℃ in the fourth zone. The entire cooling process takes approximately 35 minutes. The temperature difference between various measuring points on the workpiece surface is less than 15℃. After cooling, the workpiece shows no deformation or cracks. Metallographic examination shows good microstructure uniformity, meeting the requirements of the heat treatment process.

[0044] The following is another specific embodiment 2 of this utility model: This embodiment 2 is based on embodiment 1, but the blade surface of the spiral blade is changed to a wave-shaped structure. The wave undulates periodically along the spiral direction of the spiral blade. The peak height of the wave is 12mm higher than that of the straight blade surface, and the trough depth is 8mm lower than that of the straight blade surface. The wavelength is 150mm. This wave-shaped blade surface further enhances the disturbance effect of the airflow, so that the cooling gas continuously changes the flow direction and speed when passing through the spiral channel, forming a more complex flow field structure, which improves the convective heat transfer coefficient between the gas and the workpiece. At the same time, the wave-shaped structure increases the surface area of ​​the spiral blade by about 18%, and also increases the area of ​​the blade itself participating in heat exchange. Under the same gas flow conditions, the cooling assembly using wave-shaped blades shortens the total cooling time of the workpiece by about 12%, and the temperature uniformity is further improved. The temperature difference between each measuring point is reduced to within 10℃. In addition, the wave-shaped structure also improves the vibration resistance of the spiral blade and reduces the blade vibration and noise caused by the impact of high-speed airflow.

[0045] The following is another specific embodiment 3 of this utility model: Embodiment 3 is based on Embodiment 1, in which an annular partition is set every 500mm axially within the annular space between the guide tube and the slow-cooling cavity. The outer edge of the annular partition is fixed to the inner wall of the slow-cooling cavity, while the inner edge maintains a 20mm gap with the outer wall of the guide tube. The annular partition divides the annular space into multiple relatively independent chambers. The ceramic fiber insulation material filled in each chamber is isolated from each other. This partitioned insulation structure effectively prevents the insulation material from axially collapsing and displacing due to its own weight compression during long-term high-temperature use, maintaining the uniformity of the insulation layer thickness. In addition to improving stability, the annular baffle also enhances the overall rigidity of the slow-cooling cavity, reducing radial deformation during thermal expansion and contraction. The annular baffle is made of 3mm thick 304 stainless steel and is connected to the inner wall of the slow-cooling cavity by intermittent welding. The weld length is 50mm and the interval is 100mm. This welding method ensures the connection strength while reducing the thermal stress and deformation introduced by welding. Actual use shows that after adding the annular baffle, the temperature of the outer wall of the slow-cooling cavity is reduced by about 8℃, and the insulation effect is significantly improved. After the equipment has been running continuously for 500 hours, the insulation layer has not shown obvious sinking, and the concentricity of the guide tube remains good.

[0046] Specifically, the principle of this invention is as follows: This device utilizes multiple cooling zones formed by spiral blades within the guide tube. By employing a progressively increasing pitch structure, it controls the flow rate and residence time of the cooling airflow. In the area with a smaller pitch at the inlet, the cooling airflow is forced to move slowly along a tight spiral channel, facilitating sufficient heat exchange with the workpiece surface and achieving rapid initial cooling. As the airflow moves towards the outlet, the pitch gradually increases, accelerating the airflow velocity while reducing the heat exchange intensity per unit time, thus achieving a natural decrease in cooling intensity. This structural design allows the workpiece temperature to decrease smoothly according to a gradient from fast to slow, avoiding the problem of internal stress concentration caused by a single cooling rate. The stepped increase in the diameter of the heat dissipation holes on the outer wall of the central tube matches the varying cooling intensity of the spiral zones. In the initial area requiring stronger cooling, the heat dissipation holes are smaller to concentrate the cooling medium's effect; in the later areas, the holes are larger to diffuse the cooling medium's range of action. The two work synergistically... The combined effect enables precise graded control of cooling intensity; the small gap reserved between the outer edge of the spiral blades and the inner wall of the guide tube allows for a small amount of air leakage. This leakage airflow forms a lateral exchange between each spiral channel, which plays a role in balancing the pressure and flow rate in each channel, eliminating the phenomenon of excessively strong or weak local airflow caused by processing errors or installation deviations; the venting grooves on the spiral blades and the spiral reinforcing ribs arranged in opposite directions on the central tube further enhance the three-dimensional mixing effect of the airflow, breaking the laminar flow state of the airflow and forming a gentle turbulent flow, which significantly improves the heat exchange coefficient without significantly increasing the flow resistance; the combined design of the polygonal cross section of the guide tube and the diffuser cone section ensures that the airflow has good uniformity and appropriate flow velocity when it enters the spiral channel. The various technical features of the entire device work together to form a complete multi-stage slow cooling system, fundamentally solving the technical problems of single cooling rate and uneven distribution in traditional cooling methods.

[0047] In use, first place the high-temperature workpiece, which has undergone heat treatment and heating, in the hollow area of ​​the central tube or suspend it on the workpiece support passing through the central tube, ensuring that the workpiece is within the effective cooling area of ​​the guide tube. Then, start the cooling gas source system to introduce cooling gas into the air inlet of the slow cooling chamber. The cooling gas can be room temperature air or, depending on the process requirements, inert gases such as nitrogen. The cooling gas first undergoes preliminary diffusion and deceleration through the diffusion cone section, and is evenly distributed around the guide tube under the guidance of the radial guide ribs. Subsequently, the airflow enters the annular channel between the guide tube and the slow cooling chamber. A portion of the airflow enters the spiral channel formed by the spiral blades from the air inlet of the guide tube and begins to travel along the spiral path. One part of the airflow flows radially, while another part enters the central tube through the heat dissipation holes on the outer wall of the central tube and directly impacts the workpiece surface. Guided by the spiral blades, the airflow gradually flows from the first cooling zone to the subsequent zones. Due to the difference in screw pitch, the airflow velocity and residence time are different in each zone, thus achieving a graded cooling effect. The workpiece temperature drops rapidly to the medium temperature range in the first zone, continues to drop steadily in the middle zone, and approaches the ambient temperature in the last zone. The overall cooling rate is controlled by adjusting the inlet pressure and flow rate throughout the cooling process. When the workpiece temperature drops to the target temperature required by the process, the air supply is stopped, the discharge end of the slow cooling chamber is opened, and the workpiece is taken out to complete the entire cooling process.

Claims

1. A multi-stage slow cooling assembly for a heat treatment cooling device, used for staged cooling of a heat-treated workpiece, comprising a slow cooling chamber, a guide tube disposed inside the slow cooling chamber, spiral blades fixed to the inner wall of the guide tube, and a central tube penetrating the axis of the guide tube, characterized in that, The spiral blades are distributed along the axial direction of the guide tube to form multiple cooling zones. The pitch of the spiral blades in each cooling zone increases progressively along the airflow direction. Multiple rows of heat dissipation holes are opened on the outer wall of the central tube along the axial direction. The diameter of the heat dissipation holes increases in a stepped manner from the air inlet end to the air outlet end of the guide tube. An annular channel is formed between the inner wall of the guide tube and the outer edge of the spiral blades. The angle between the blade surface of the spiral blades and the axis of the guide tube is 35~55°. The inner wall of the slow cooling cavity is provided with several sets of boss structures. The boss structures are evenly distributed along the circumference of the slow cooling cavity and are used to provide radial positioning support for the guide tube.

2. The multi-stage slow cooling component of a heat treatment cooling device according to claim 1, characterized in that, The spiral blades form a transition section at the junction of two adjacent cooling zones, and the thickness of the spiral blades in the transition section is greater than the thickness of the spiral blades at other locations within the same cooling zone.

3. The multi-stage slow cooling component of a heat treatment cooling device according to claim 2, characterized in that, The central tube is provided with reinforcing ribs along the axial direction. The reinforcing ribs are distributed in a spiral shape on the outer wall surface of the central tube, and the spiral direction of the reinforcing ribs is opposite to that of the spiral blades.

4. The multi-stage slow cooling component of a heat treatment cooling device according to claim 3, characterized in that, The cross-section of the guide tube is polygonal, and each side of the polygonal structure is connected to the adjacent side by an arc transition surface. The radius of curvature of the arc transition surface is less than 1 / 10 of the equivalent circle diameter of the guide tube.

5. The multi-stage slow cooling component of a heat treatment cooling device according to claim 4, characterized in that, The spiral blade has several ventilation grooves on its blade surface. The ventilation grooves extend along the radial direction of the spiral blade, and the width of the ventilation grooves gradually increases from the inner edge to the outer edge of the spiral blade.

6. The multi-stage slow cooling component of a heat treatment cooling device according to claim 5, characterized in that, The air inlet of the slow cooling cavity is provided with a diffusion cone section, the cone angle of which is 15~25°, and the inner wall surface of the diffusion cone section is provided with guide ribs, which are distributed radially.

7. The multi-stage slow cooling component of a heat treatment cooling device according to claim 6, characterized in that, The gap between the outer edge of the spiral blade and the inner wall of the guide tube is less than 1 / 5 of the height of the spiral blade in the radial direction, and the gap remains constant along the axial direction of the guide tube.

8. The multi-stage slow cooling component of a heat treatment cooling device according to claim 7, characterized in that, The heat dissipation holes of the central tube are arranged in a quincunx pattern, and the ratio of the axial spacing to the circumferential spacing between adjacent heat dissipation holes is 3:

2. The hole walls of the heat dissipation holes have a chamfered structure.

9. The multi-stage slow cooling component of a heat treatment cooling device according to claim 8, characterized in that, The guide tube is made of heat-resistant stainless steel, and the spiral blades are fixed to the inner wall of the guide tube by argon arc welding. The welded joint has a continuous weld structure.

10. The multi-stage slow cooling component of a heat treatment cooling device according to claim 9, characterized in that, The annular space formed between the slow cooling cavity and the guide tube is filled with ceramic fiber insulation material. The thickness of the ceramic fiber insulation material is evenly distributed along the axial direction of the slow cooling cavity. The top surface of the boss structure and the outer wall surface of the guide tube form a point contact support.

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