Double-end screw heat treatment device and process thereof

Abstract

The invention relates to the technical field of fastener heat treatment, in particular to a double-end screw heat treatment device and a process thereof.The double-end screw heat treatment device comprises a heating furnace body internally provided with a heating cavity, a conveying belt is arranged in the heating furnace body, a feeding port and a discharging port are formed in the two ends of the heating furnace body respectively, and the two ends of the conveying belt extend out of the feeding port and the discharging port; a plurality of chain plates are arranged on the conveying belt; a heating element, a heat treatment unit and a waste heat recovery unit are arranged in the heating cavity; the heat treatment unit comprises rolling mechanisms arranged on chain plates, screws are driven to turn over by means of synchronous rotation of rotating rollers, periodic direction changing of hot air is achieved through an air direction adjusting mechanism, and vibration generated by rolling steel balls in the rotating rollers is matched, so that the screws are heated evenly, and thread damage is avoided. Meanwhile, waste heat of high-temperature oil mist and waste gas is recycled through the heat exchange mechanism and is circularly blown to the screws to save energy and improve efficiency, the oil mist can be rapidly discharged, loosening and oil dirt blowing off can be achieved, and the surface defects such as oil dirt and hard spots are reduced.

Description

Technical Field

[0001] This application relates to the technical field of fastener heat treatment, and in particular to a heat treatment apparatus and process for a double-ended screw. Background Technology

[0002] In fields such as machinery manufacturing, construction engineering, and aerospace, double-ended studs are core fasteners with bidirectional tightening functions. Their mechanical properties, such as tensile strength, yield strength, and toughness, along with surface quality, directly determine the stability and service life of the assembled structure. Heat treatment is a key process for improving the overall performance of double-ended studs. By precisely controlling the heating, holding, and cooling processes, the internal metallographic structure of the screw is altered, achieving an optimized balance between strength and toughness.

[0003] Lubricating oil is applied during cold heading and other processes before heat treatment to reduce machining resistance. This oil adheres to the screw surface through physical adsorption and grease penetration, forming an oil film. During heat treatment, the oil film evaporates under heating to form oil mist, which easily reacts with oxygen at high temperatures to form carbon deposits. After condensation, it adheres to the screw surface and easily forms grease buildup.

[0004] A search revealed Chinese Patent Publication No. CN120738446B, which discloses a heat treatment strengthening process and apparatus for carbon steel rivet nuts. The process includes the following steps: S1, quenching a cold-headed carbon steel rivet nut in a heating furnace; S2, tempering the quenched carbon steel rivet nut at 396~410℃ and then cooling; S3, tempering the tempered carbon steel rivet nut at 272~295℃ and then cooling, resulting in a heat-treated and strengthened carbon steel rivet nut. By precisely controlling the phase transformation behavior of medium carbon steel and combining it with two-stage tempering, the deformed portion of the rivet nut acquires a tempered troostite structure with uniform carbide strengthening, resulting in a significant simultaneous increase in both tensile strength and yield strength.

[0005] Regarding the aforementioned technologies, the inventors have discovered the following drawbacks: In conventional heat treatment devices, double-ended screws are statically stacked or transported by a simple conveyor belt. The varying distances between the screw surface and the heat source result in uneven temperature distribution on the screw surface, leading to inconsistent internal metallographic transformations and consequently, significant fluctuations in mechanical properties such as tensile strength, yield strength, and toughness. Furthermore, traditional devices rely solely on natural ventilation from the top of the furnace or a simple negative pressure extraction system to remove oil mist. This results in prolonged oil retention time in the conveying mechanism within the furnace, easily condensing on the screw surface to form oil deposits. This not only affects the processing results of subsequent pickling and electroplating processes but also causes defects such as pitting and corrosion on the screw surface. Summary of the Invention

[0006] To ensure more uniform heating of double-ended screws and reduce defects caused by oil buildup, this application provides a heat treatment apparatus and process for double-ended screws.

[0007] This application provides a double-headed screw heat treatment device, which adopts the following technical solution: It includes a heating furnace body with an internal heating chamber, characterized in that: a conveyor belt is provided inside the heating furnace body, and inlet and outlet are respectively provided at both ends of the heating furnace body; both ends of the conveyor belt extend out from the inlet and outlet; multiple chain plates are provided on the conveyor belt; a heating element, a heat treatment unit, and a waste heat recovery unit are provided inside the heating chamber; the heat treatment unit includes a rolling mechanism provided on each chain plate, the rolling mechanism including placement frames symmetrically arranged at the front and rear ends of the chain plate, and multiple rotating rollers rotatably connected between two placement frames; a cylindrical placement part is coaxially fixed on each rotating roller, and a bolt placement space is formed between the placement parts of two adjacent rotating rollers; the waste heat recovery unit includes a heat exchange mechanism communicating with the heating chamber, and a wind box communicating with the heat exchange mechanism; the wind box is located between the upper and lower rings of the conveyor belt inside the heating furnace body, and a first air outlet is provided on both the top and bottom walls of the wind box; each chain plate is provided with an air direction adjustment mechanism and an air passage hole. The conveyor belt runs through the inlet and outlet, and together with the chain plate, it enables continuous feeding and discharging of double-ended screws, adapting to batch heat treatment needs and avoiding the inefficiency of intermittent batch operations. The cylindrical placement part of the rotating roller forms a dedicated bolt placement space, with the placement part only contacting the smooth part in the middle of the screw, avoiding damage to the threaded part and ensuring screw precision.

[0008] Optionally, the wind direction adjustment mechanism includes mounting brackets fixedly installed on the front and rear sidewalls of each air passage, with multiple guide vanes rotatably connected between the two mounting brackets, and each guide vane having a transmission hole on its sidewall; each chain plate is fixedly provided with a first sliding cylinder, each first sliding cylinder is slidably connected with a first sliding rod, and each first sliding rod has a transmission rod on its sidewall that can be inserted into the transmission hole; the diameter of the transmission hole is larger than that of the transmission rod; a compression spring is provided between the bottom wall of the first sliding cylinder and the corresponding surface of the first sliding rod.

[0009] Optionally, a third rack is fixedly mounted on the first sliding rod, and an intermittent gear meshing with the third rack is coaxially fixedly mounted on one of the rotating rollers on each chain plate; a portion of the peripheral wall of the intermittent gear is a smooth surface, and the other portion is a toothed surface. The guide vane can rotate flexibly, and in conjunction with the transmission rod and transmission hole, it can precisely change the direction of the airflow passing through the air passage, avoiding dead zones on the screw surface, allowing all parts of the screw to fully contact the hot air, and improving the uniformity of heating and heat dissipation. The toothed surface and smooth surface of the intermittent gear alternately mesh with the third rack, and with the reset action of the compression spring, drive the first sliding rod to slide back and forth, thereby causing the guide vane to deflect periodically, continuously changing the direction of the hot air, further enhancing the uniformity of airflow coverage on the screw surface, and reducing local temperature differences.

[0010] Optionally, each rotating roller is a hollow cylindrical structure, and a rotating frame is provided inside the rotating roller. A rotating rod is rotatably connected to each rotating frame, and multiple sector-shaped parts are arranged radially on each rotating rod. Each sector-shaped part is a sector-shaped body, and the arc of the sector-shaped surface is consistent with the arc of the inner wall of the rotating roller, and the sector-shaped surface abuts against the inner wall of the rotating roller. Each sector-shaped part is provided with a placement cavity, and rolling steel balls are arranged in the placement cavity.

[0011] Optionally, a first sprocket is fixedly sleeved on the outer wall of each rotating roller, and the first sprockets on the same chain plate are sleeved on the same first chain; a first transmission gear is coaxially fixedly installed on one of the rotating rollers on each chain plate, and a first rack that can intermittently mesh with the first transmission gear is fixedly installed on the inner wall of the heating furnace.

[0012] Optionally, a second sprocket is fixedly sleeved on the outer wall of each rotating rod, and the second sprockets on the same chain plate are meshed with the same second chain; a second transmission gear is coaxially fixedly installed on one of the rotating rods on each chain plate, and a second rack that can intermittently mesh with the second transmission gear is fixedly installed on the inner wall of the heating furnace.

[0013] Optionally, the heat exchange mechanism includes an air intake on the top wall of the heating furnace and a heat exchange box connected to the air intake; a coil is installed inside the heat exchange box, and multiple fins are fixedly installed on the outer wall of the coil; one end of the coil is connected to the air intake, and the other end is connected to an external waste gas treatment device through a first suction pump. This allows for the full absorption of heat from the high-temperature oil mist and waste gas in the heating chamber, improving heat exchange efficiency; simultaneously, the first suction pump guides the waste gas into the external treatment device, meeting environmental protection requirements and preventing air pollution.

[0014] Optionally, the heat exchange box has an air inlet and a second air outlet on its side wall. The second air outlet is connected to the air box via a second suction pump. The hot air after heat exchange is sent into the air box by the second suction pump and blown onto the screw surface, which not only recovers waste heat and reduces energy consumption, but also accelerates the discharge of oil mist and improves heat treatment efficiency.

[0015] Optionally, each end of the heating furnace body is provided with a support frame, and each support frame is rotatably connected to two support rods. A third sprocket is fixedly fitted onto each support rod. A third chain is meshed between the two third sprockets at the left and right ends of the heating furnace body, and the third chain is fixedly connected to the corresponding chain plate. A drive motor is fixedly mounted on one of the support frames, and the output shaft of the drive motor is coaxially fixedly connected to the corresponding support rod. Through the chain drive structure of the second sprocket and the second chain, combined with the intermittent meshing of the second transmission gear and the second rack, all rotating rods on the same chain plate can be driven to rotate synchronously, causing the rolling steel balls to vibrate uniformly, loosening the oil stains on the surface of the rotating rollers, and avoiding secondary contamination.

[0016] A heat treatment process for double-ended screws includes the following steps: S1. Start the heating element of the heating furnace body to preheat the heating chamber to the preset heat treatment temperature; at the same time, start the drive motor to drive the conveyor belt to circulate through the support rod, the third sprocket and the third chain; S2. Insert the double-ended screw to be heat-treated into the feed port of the heating furnace body, so that the middle bare part of the screw is embedded into the bolt placement space formed between the placement parts of the adjacent rotating rollers, and the screw enters the heating chamber with the chain plate; S3. When the chain plate moves to the first rack area, the first transmission gear meshes with the first rack, and through the first chain and the first sprocket, drives all the rotating rollers on the same chain plate to rotate synchronously, driving the screws to flip and achieve uniform heating; S4. Start the first suction pump to draw the high-temperature oil mist and exhaust gas in the heating chamber to the heat exchanger coil, where they exchange heat with the cold air; start the second suction pump to send the heated air into the air box, blow it out from the first air outlet, and pass through the air passage of the chain plate to act on the screw surface; S5. The rotation of the rotating roller drives the intermittent gear to rotate synchronously. When the tooth surface of the intermittent gear meshes with the third rack, it pushes the first sliding rod to slide, which drives the guide vane to deflect through the transmission rod. When the smooth surface of the intermittent gear is opposite to the third rack, the compressed spring pushes the sliding rod to move back, the guide vane resets, and the hot air direction changes periodically in a cycle. S6. When the chain plate moves to the second rack area of ​​the lower ring of the conveyor belt, the second transmission gear meshes with the second rack, and drives all the rotating rods on the same chain plate to rotate synchronously through the second chain and the second sprocket. The rolling steel balls roll in the placement cavity and generate vibration, which is transmitted through the rotating roller and combined with hot air to remove surface oil stains; S7. The high-temperature oil mist and exhaust gas after heat exchange in the heat exchange box are transported to the external exhaust gas treatment device by the first suction pump to meet emission standards; S8. The heat-treated screws move with the chain plate to the discharge port or fall naturally in the turning area of ​​the conveyor belt and are collected by the collection device.

[0017] In summary, this application includes the following beneficial technical effects: 1. In this invention, the rotating rollers on the same chain plate are linked to the first chain via a first sprocket. When the chain plate moves with the conveyor belt, the first transmission gear intermittently meshes with the first rack on the inner wall of the furnace, driving all rotating rollers to rotate synchronously, thereby driving the double-ended screws placed in the bolt placement space to flip. This design solves the problem of uneven local heating caused by traditional static stacking or simple conveying, ensuring that the distance between each part of the screw and the heating element remains consistent, resulting in a more uniform metallographic transformation and smaller fluctuations in mechanical properties such as tensile strength and yield strength. The cylindrical placement parts of adjacent rotating rollers form a placement space that matches the double-ended screws, allowing only the middle shank of the screw to contact the placement part, while the threaded part is completely suspended, avoiding friction and compression between the thread and rotating parts during heat treatment, and preventing thread deformation, burr formation, or thread damage.

[0018] 2. The airflow adjustment mechanism of this invention, through the meshing transmission of an intermittent gear and a third rack, drives the guide vanes to rotate periodically, causing the direction of the hot air blown out of the bellows to change alternately. This further ensures uniform heating of the double-ended screws and the rotating roller, reduces the risk of deformation of the double-ended screws, and ensures that the rotating roller can still be continuously heated even when it is rotated away from the heating element, allowing for more comprehensive evaporation of oil stains on the rotating roller. The first suction pump continuously extracts the high-temperature oil mist generated by the evaporation of lubricating oil on the screw surface during heat treatment in the furnace through the suction port.

[0019] 3. In this invention, the rolling steel balls located in the lower ring of the conveyor belt rotate and vibrate under the drive of the rotating rod. The vibration is transmitted to the rotating roller through the fan-shaped part, loosening the oil stains attached to the surface of the rotating roller and the screws. In addition, the hot air blown out by the bellows blows the oil stains downwards, avoiding the oil stains from contaminating the bolts to be heat treated. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure in an embodiment of this application; Figure 2 This is a schematic diagram of the rolling mechanism in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the sector portion in an embodiment of this application; Figure 4 This is a schematic cross-sectional view of the sector-shaped portion in an embodiment of this application; Figure 5 This is a schematic diagram of the chain plate structure in an embodiment of this application; Figure 6 This is a schematic diagram of the intermittent gear and the third rack in an embodiment of this application; Figure 7 This is a cross-sectional structural diagram of the heat exchange box in an embodiment of this application; Figure 8 This is a schematic diagram of the structure of the first sliding rod in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of the first sliding cylinder in an embodiment of this application; Figure 10 This is a schematic diagram of the heating furnace body in an embodiment of this application.

[0021] Reference numerals: 1. Heating furnace body; 2. Heating chamber; 3. Feed inlet; 4. Discharge outlet; 5. Conveyor belt; 6. Chain plate; 7. Heating element; 8. Placement rack; 9. Rotating roller; 10. Placement section; 11. Placement space; 12. Rotating frame; 13. Rotating rod; 14. Sector-shaped section; 15. Placement chamber; 16. Rolling steel ball; 17. First sprocket; 18. First chain; 19. First transmission gear; 20. Third rack; 21. Second sprocket; 22. Second chain; 23. Second transmission gear; 24. Second rack; 25. Bellows; 26. First air outlet; 27. Air passage hole; 28. Air intake; 29. ​​Heat exchange box; 30. Coil; 31. Fin; 32. First suction pump; 33. Air inlet; 34. Second air outlet; 35. Second suction pump; 36. Mounting bracket; 37. Guide vane; 38. Transmission hole; 39. First sliding cylinder; 40. First sliding rod; 41. Transmission rod; 42. Compression spring; 43. First rack; 44. Intermittent gear; 45. Support frame; 46. Support rod; 47. Third sprocket; 48. Third chain; 49. Drive motor. Detailed Implementation

[0022] The following is in conjunction with the appendix Figures 1-10 This application will be further described in detail below. The technical solutions in the embodiments of this application will be clearly described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0023] This application discloses a heat treatment apparatus for double-ended screws. For example... Figure 1 As shown in the embodiment of this application, the double-ended screw heat treatment device includes a heating furnace body 1, with a heating chamber 2 formed inside the heating furnace body 1. A feed inlet 3 is located at the left end of the heating furnace body 1, and a discharge outlet 4 is located at the right end. A conveyor belt 5 is installed inside the heating furnace body 1, passing through the feed inlet 3 and the discharge outlet 4. The conveyor belt 5 is composed of multiple sequentially hinged chain plates 6, which circulate with the conveyor belt 5 to achieve continuous conveying of the double-ended screws. Heating elements 7 (preferably electric heating tubes in this embodiment, evenly distributed at the top of the heating chamber 2), a heat treatment unit, and a waste heat recovery unit are fixedly installed inside the heating chamber 2. The heating elements 7 provide a stable heat source for the heating chamber 2, the heat treatment unit achieves uniform heat treatment of the double-ended screws, and the waste heat recovery unit recovers and recycles the waste heat inside the furnace.

[0024] like Figure 2 As shown, in this invention, the heat treatment unit includes a rolling mechanism disposed on each chain plate 6. The rolling mechanism consists of placement frames 8 symmetrically fixed at the front and rear ends of the chain plate 6. Multiple rotating rollers 9 are rotatably connected between two placement frames 8 via bearings, and the rotating rollers 9 are evenly distributed along the length of the chain plate 6. Each rotating roller 9 has a cylindrical placement part 10 coaxially fixed on it. A bolt placement space 11 adapted to a double-ended screw is formed between the placement parts 10 of two adjacent rotating rollers 9, ensuring that the middle smooth part of the screw can contact the placement part 10, avoiding contact between the threaded part of the screw and the rotating roller, thereby preventing damage to the threaded part of the screw.

[0025] like Figure 3 and Figure 4 As shown, in this invention, each rotating roller 9 adopts a hollow cylindrical structure. A rotating frame 12 is coaxially arranged inside the rotating roller 9. The rotating frame 12 is rotatably connected to a rotating rod 13 via bearings. Multiple sector-shaped portions 14 are uniformly fixed radially on the rotating rod 13. The sector-shaped portions 14 have a sector-shaped structure, and the arc of their sector-shaped surfaces is completely consistent with the arc of the inner wall of the rotating roller 9, and the sector-shaped surfaces are in close contact with the inner wall of the rotating roller 9. Each sector-shaped portion 14 has a placement cavity 15, and multiple rolling steel balls 16 are placed in the placement cavity 15. When the rotating rod 13 rotates, the rolling steel balls 16 roll in the placement cavity 15, which can generate vibration, and the vibration is transmitted to the rotating roller 9 through the sector-shaped surfaces.

[0026] To achieve synchronous rotation of the rotating roller 9, such as Figure 2 As shown, in this invention, a first sprocket 17 is fixedly sleeved on the outer wall of each rotating roller 9, and all the first sprockets 17 on the same chain plate 6 are sleeved on the same first chain 18, forming a chain drive structure. A first transmission gear 19 is coaxially fixed on the leftmost rotating roller 9 on each chain plate 6, and a first rack 43 is fixedly installed at the corresponding position on the inner wall of the heating furnace body 1. The first rack 43 extends along the movement direction of the conveyor belt 5 and can intermittently mesh with the first transmission gear 19. When the chain plate 6 moves with the conveyor belt 5 to the area of ​​the first rack 43, the first transmission gear 19 meshes with the first rack 43, driving the corresponding rotating roller 9 to rotate. Through the transmission of the first chain 18, all the rotating rollers 9 on the same chain plate 6 rotate synchronously, thereby driving the double-headed screws placed in the bolt placement space 11 to flip, so that the double-headed screws are heated more evenly. In this embodiment, the first rack 43 is disposed in the upper and lower rings of the conveyor belt 5, and the first rack 43 meshes with the first transmission gear located in the upper and lower rings of the conveyor belt 5.

[0027] Similarly, such as Figure 2As shown, in this invention, a second sprocket 21 is fixedly sleeved on the outer wall of each rotating rod 13, and all the second sprockets 21 on the same chain plate 6 are sleeved on the same second chain 22. A second transmission gear 23 is coaxially fixed on the rightmost rotating rod 13 on each chain plate 6, and a second rack 24 is fixedly installed at a corresponding position on the inner wall of the heating furnace body 1. The second rack 24 and the second transmission gear 23 intermittently mesh. When the chain plate 6 moves to the area of ​​the second rack 24, the second transmission gear 23 meshes with the second rack 24, driving the rotating rod 13 to rotate. Through the transmission of the second chain 22, all the rotating rods 13 on the same chain plate 6 rotate synchronously, and vibration is generated in conjunction with the rolling steel balls 16. In this embodiment, the second rack 24 is disposed in the lower ring of the conveyor belt 5, and the second rack 24 meshes only with the second transmission gear located in the lower ring of the conveyor belt 5.

[0028] like Figure 7 As shown, in this invention, the waste heat recovery unit includes a heat exchange mechanism and a wind box 25. The wind box 25 is located between the upper and lower rings of the conveyor belt 5 inside the heating furnace body 1. The top and bottom walls of the wind box 25 are each provided with a uniformly distributed first air outlet 26, which can simultaneously blow air onto the chain plates 6 of the upper and lower rings. Each chain plate 6 is provided with multiple air passage holes 27, which correspond to the first air outlet 26, ensuring that the airflow can pass through the chain plate 6 and act on the surface of the double-headed screw.

[0029] The heat exchange mechanism includes an air intake 28 located on the top wall of the heating furnace body 1. The air intake 28 is connected to a heat exchange box 29. A coil 30 is fixedly installed inside the heat exchange box 29, and multiple fins 31 are welded to the outer wall of the coil 30 to improve heat exchange efficiency. One end of the coil 30 is connected to the air intake 28, and the other end is connected to an external waste gas treatment device (not shown in the figure) through a first suction pump 32, which is used to extract and treat the high-temperature oil mist and waste gas in the heating chamber 2. The side wall of the heat exchange box 29 has an air inlet 33 and a second air outlet 34. The second air outlet 34 is connected to a wind box 25 through a second suction pump 35. External cold air enters the heat exchange box 29 from the air inlet 33, exchanges heat with the high-temperature waste gas in the coil 30, and is then heated up before being sent into the wind box 25 by the second suction pump 35 to realize waste heat recovery and utilization.

[0030] like Figure 6As shown, in this invention, each chain plate 6 is equipped with an airflow adjustment mechanism. The airflow adjustment mechanism includes a mounting bracket 36 fixed to the front and rear side walls of each air passage 27. Multiple guide vanes 37 are rotatably connected between two mounting brackets 36 via pins. Each guide vane 37 has a transmission hole 38 on its side wall. Two first sliding cylinders 39 are fixedly installed on each chain plate 6. A first sliding rod 40 is slidably connected inside the first sliding cylinder 39. A transmission rod 41 is fixedly installed on the side wall of the first sliding rod 40. The transmission rod 41 is inserted into the corresponding transmission hole 38, and the diameter of the transmission hole 38 is larger than the diameter of the transmission rod 41, providing space for the rotation of the guide vane 37. A compression spring 42 is provided between the bottom wall of the first sliding cylinder 39 and the corresponding surface of the first sliding rod 40. The compression spring 42 is always in a compressed state, providing a restoring force for the first sliding rod 40.

[0031] A third rack 20 is fixedly mounted on the first sliding rod 40. An intermittent gear 44 is coaxially fixed on one of the rotating rollers 9 on each chain plate 6. Part of the peripheral wall of the intermittent gear 44 is a smooth surface, and the other part is a toothed surface, which can mesh with the third rack 20. When the rotating roller 9 rotates, the intermittent gear 44 rotates synchronously. When its toothed surface meshes with the third rack 20, it drives the first sliding rod 40 to slide along the first sliding cylinder 39, which in turn drives the guide vane 37 to rotate through the transmission rod 41, thereby achieving wind direction adjustment. When the smooth surface of the intermittent gear 44 is opposite to the third rack 20, the compression spring 42 pushes the first sliding rod 40 to reset, and the guide vane 37 returns to its initial angle, thus achieving periodic changes in wind direction.

[0032] like Figure 1 As shown, in this invention, a support frame 45 is fixedly installed at both the left and right ends of the heating furnace body 1. Each support frame 45 is rotatably connected to two support rods 46 via bearings, and a third sprocket 47 is fixedly sleeved on each support rod 46. A third chain 48 is meshed between the two third sprockets 47 at the left end of the heating furnace body 1, and a third chain 48 is also meshed between the two third sprockets 47 at the right end. The third chain 48 is fixedly connected to the corresponding chain plate 6. A drive motor 49 is fixedly installed on one of the support frames 45. The output shaft of the drive motor 49 is coaxially fixedly connected to the corresponding support rod 46. The drive motor 49 drives the support rod 46 to rotate, which in turn drives the conveyor belt 5 to circulate through the third chain 48.

[0033] A heat treatment process for double-ended screws includes the following steps: S1. Start the heating element of the heating furnace body 1 to preheat the heating chamber 2 to the preset heat treatment temperature; at the same time, start the drive motor to drive the conveyor belt 5 to circulate through the support rod, the third sprocket and the third chain to prepare for continuous screw conveying; S2. Insert the double-ended screw to be heat-treated into the feed port at the left end of the heating furnace body 1, so that the middle bare part of the screw is embedded in the bolt placement space 11 formed between the placement parts 10 of the adjacent rotating rollers 9, so as to avoid the threaded part from contacting the rotating rollers 9. The screw enters the heating chamber 2 synchronously with the chain plate 6. S3. When the chain plate 6 moves to the area of ​​the first rack 43, the first transmission gear 19 meshes with the first rack 43, and drives all the rotating rollers 9 on the same chain plate 6 to rotate synchronously through the first chain 18 and the first sprocket 17, thereby driving the screw to rotate continuously, ensuring that all parts of the screw are in full contact with the heat source and achieving uniform heating. S4. Start the first suction pump 32 to draw the high-temperature oil mist and exhaust gas in the heating chamber 2 into the coil 30 of the heat exchange box 29, where they exchange heat with the cold air entering from the air inlet 33; at the same time, start the second suction pump 35 to send the heated air after heat exchange into the air box 25, and blow it out from the first air outlet 26 above and below the air box 25, passing through the air passage 27 of the chain plate 6 and acting on the lower surface of the screw and the rotating roller 9. S5. When the rotating roller 9 rotates, it drives the intermittent gear 44 to rotate synchronously. When its tooth surface meshes with the third rack 20, it pushes the first sliding rod 40 to slide and compresses the spring 42. Through the transmission rod 41, it drives the guide vane 37 to deflect. When the smooth surface of the intermittent gear 44 is opposite to the third rack 20, the spring resets and pushes the first sliding rod to move back. The guide vane 37 returns to its initial angle, and the hot air direction changes periodically in a cycle, improving the uniformity of airflow. S6. When the chain plate 6 moves to the area of ​​the second rack 24 of the lower ring of the conveyor belt 5, the second transmission gear 23 meshes with the second rack 24, and drives the second chain 22 and the second sprocket 21 to drive all the rotating rods 13 on the same chain plate 6 to rotate synchronously; the rolling steel balls 16 roll in the placement cavity 15 of the fan-shaped part 14 to generate vibration, which is transmitted to the screw and the surface of the rotating roller 9 through the rotating roller 9, loosening the attached oil stains, and the oil stains are blown away with the help of hot air; S7. The high-temperature oil mist and exhaust gas after heat exchange in the heat exchange box 29 are transported to the external exhaust gas treatment device by the first suction pump 32 and discharged after meeting the standards. S8. The screws that have completed heat treatment move with the chain plate 6 to the discharge port at the right end of the heating furnace body, or fall naturally in the turning area of ​​the conveyor belt 5, and are collected by the preset collection box. Workflow: Start the drive motor 49, and its output shaft drives the connected support rod 46 to rotate. The third sprocket 47 on the support rod 46 rotates synchronously, and drives the conveyor belt 5 composed of multiple hinged chain plates 6 to circulate through the third chain 48, laying the foundation for the continuous conveying of double-headed screws. The double-ended screw to be heat-treated is placed into the feed port 3 at the left end of the heating furnace body 1. The middle smooth part of the screw is placed in the bolt placement space 11 formed between the placement parts 10 of the adjacent rotating rollers 9 to avoid the threaded part from contacting the rotating rollers 9 and to prevent thread damage. The screw enters the heating chamber 2 together with the chain plate 6. The electric heating tube (heating element 7) at the top of the heating chamber 2 is activated to provide a stable heat source for the heating chamber 2 and initially heat the screw. When the chain plate 6 moves to the area of ​​the first rack 43 (the upper and lower rings of the conveyor belt 5 are equipped with the first rack 43), the first transmission gear 19 on the leftmost rotating roller 9 of the chain plate 6 meshes with the first rack 43, driving the rotating roller 9 to rotate. Through the chain drive structure of the first chain 18 and the first sprocket 17, all rotating rollers 9 on the same chain plate 6 rotate synchronously, thereby driving the screw to flip and ensuring that all parts of the screw are heated evenly. The first suction pump 32 starts and extracts the high-temperature oil mist and exhaust gas in the heating chamber 2 through the air intake 28 on the top wall of the heating furnace body 1, and sends them into the coil 30 of the heat exchange box 29, and finally delivers them to the external exhaust gas treatment device for treatment; external cold air enters from the air inlet 33 of the heat exchange box 29, and exchanges heat with the high-temperature exhaust gas in the coil 30 (with fins 31 welded to the outer wall to improve heat exchange efficiency) and is heated up; the second suction pump 35 extracts the heated hot air from the second air outlet 34 of the heat exchange box 29 and sends it into the air box 25 located between the upper and lower rings of the conveyor belt 5; Hot air is blown out from the first air outlet 26 on the top and bottom walls of the wind box 25, passes through the air passage hole 27 on the chain plate 6, and acts on the screw surface to realize the recovery and utilization of waste heat. At the same time, the evaporated oil mist is blown upward to reduce the residence time of the oil mist in the heating chamber 2. When the rotating roller 9 rotates, the coaxially fixed intermittent gear 44 rotates synchronously. When the tooth surface of the intermittent gear 44 meshes with the third rack 20 on the first sliding rod 40, it drives the first sliding rod 40 to slide along the first sliding cylinder 39. The compression spring 42 is further compressed, and the transmission rod 41 on the first sliding rod pushes the guide vane 37 to rotate around the pin shaft, changing the direction of the hot air. When the smooth surface of the intermittent gear 44 is opposite to the third rack 20, the compression spring 42 releases its elastic force, pushes the first sliding rod 40 to reset, and the guide vane 37 returns to its initial angle. This cycle is repeated to achieve periodic changes in wind direction and ensure that the screw surface is evenly exposed to wind. When the chain plate 6 moves to the turning area of ​​the conveyor belt 5, the double-headed screw falls off the chain plate 6 naturally, and the operator can place a storage box below the turning area of ​​the conveyor belt 5. When the chain plate 6 moves to the area of ​​the second rack 24 in the lower ring of the conveyor belt 5, the second transmission gear 23 on the rotating rod 13 on the chain plate 6 meshes with the second rack 24, driving the rotating rod 13 to rotate. Through the chain drive of the second chain 22 and the second sprocket 21, all rotating rods 13 on the same chain plate 6 rotate synchronously. The fan-shaped part 14 on the rotating rod 13 rotates with it, and the rolling steel balls 16 in the placement cavity 15 roll and generate vibration. The vibration is transmitted to the rotating roller 9 through the fan-shaped surface. The oil stains attached to the surface of the rotating roller 9 are loosened and blown down with the hot air blown out of the air passage 27. The rotating roller 9 makes the oil stains more thorough and avoids secondary pollution caused by oil stains adhering to the double-headed screws to be heat treated.

[0034] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A heat treatment device for double-headed screws, comprising a heating furnace body (1) with a heating chamber (2) inside, characterized in that: The heating furnace body (1) is equipped with a conveyor belt (5), and the heating furnace body (1) is equipped with a feed inlet (3) and a discharge outlet (4) at both ends. The feed inlet (3) and discharge outlet (4) extend from both ends of the conveyor belt (5). Multiple chain plates (6) are provided on the conveyor belt (5). The heating chamber (2) is equipped with a heating element (7), a heat treatment unit, and a waste heat recovery unit. The heat treatment unit includes a rolling mechanism provided on each chain plate (6). The rolling mechanism includes a placement frame (8) symmetrically arranged at the front and rear ends of the chain plate (6). Multiple rotating parts are connected between the two placement frames (8) in the same direction. Roller (9); Each rotating roller (9) is coaxially fixed with a cylindrical placement part (10), and the placement parts (10) of two adjacent rotating rollers (9) form a bolt placement space (11); The waste heat recovery unit includes a heat exchange mechanism connected to the heating chamber (2) and a wind box (25) connected to the heat exchange mechanism; The wind box (25) is located between the upper and lower rings of the conveyor belt (5) inside the heating furnace body (1), and the top and bottom walls of the wind box (25) are provided with a first air outlet (26); Each chain plate (6) is provided with a wind direction adjustment mechanism and an air passage hole (27).

2. The heat treatment apparatus for double-ended screws according to claim 1, characterized in that: The wind direction adjustment mechanism includes a mounting bracket (36) fixedly installed on the front and rear side walls of each air passage (27), and multiple guide vanes (37) rotatably connected between the two mounting brackets (36). Each guide vane (37) has a transmission hole (38) on its side wall. Each chain plate (6) is fixedly provided with a first sliding cylinder (39), and each first sliding cylinder (39) is slidably connected with a first sliding rod (40). Each first sliding rod (40) has a transmission rod (41) on its side wall that can be inserted into the transmission hole (38). The diameter of the transmission hole (38) is larger than that of the transmission rod (41). A compression spring (42) is provided between the bottom wall of the first sliding cylinder (39) and the corresponding surface of the first sliding rod (40).

3. The heat treatment apparatus for double-ended screws according to claim 2, characterized in that: A third rack (20) is fixedly provided on the first sliding rod (40), and an intermittent gear (44) that meshes with the third rack (20) is coaxially fixedly provided on one of the rotating rollers (9) on each chain plate (6); a portion of the peripheral wall of the intermittent gear (44) is a smooth surface, and the other portion is a tooth surface.

4. The heat treatment apparatus for double-ended screws according to claim 1, characterized in that: Each rotating roller (9) is a hollow cylindrical structure. A rotating frame (12) is provided inside the rotating roller (9). A rotating rod (13) is rotatably connected to each rotating frame (12). Multiple fan-shaped parts (14) are arranged radially on each rotating rod (13). Each fan-shaped part (14) is a fan-shaped body. The arc of the fan-shaped surface of the fan-shaped body is consistent with the arc of the inner wall of the rotating roller (9), and the fan-shaped surface abuts against the inner wall of the rotating roller (9). Each fan-shaped part (14) is provided with a placement cavity (15), and a rolling steel ball (16) is provided in the placement cavity (15).

5. The heat treatment apparatus for double-ended screws according to claim 1, characterized in that: Each rotating roller (9) is fixedly fitted with a first sprocket (17) on its outer wall, and the first sprockets (17) on the same chain plate (6) are fitted with the same first chain (18); a first transmission gear (19) is fixedly mounted on one of the rotating rollers (9) on each chain plate (6), and a first rack (43) that can intermittently mesh with the first transmission gear (19) is fixedly mounted on the inner wall of the heating furnace.

6. The heat treatment apparatus for a double-ended screw according to claim 4, characterized in that: Each rotating rod (13) has a second sprocket (21) fixedly fitted on its outer wall. The second sprockets (21) on the same chain plate (6) are meshed with the same second chain (22). A second transmission gear (23) is coaxially fixedly installed on one of the rotating rods (13) on each chain plate (6). A second rack (24) that can intermittently mesh with the second transmission gear (23) is fixedly installed on the inner wall of the heating furnace.

7. The heat treatment apparatus for double-ended screws according to claim 1, characterized in that: The heat exchange mechanism includes an air inlet (28) opened on the top wall of the heating furnace body (1) and a heat exchange box (29) connected to the air inlet (28); a coil (30) is provided inside the heat exchange box (29), and multiple fins (31) are fixedly provided on the outer wall of the coil (30); one end of the coil (30) is connected to the air inlet (28), and the other end is connected to an external waste gas treatment device through a first suction pump (32).

8. The heat treatment apparatus for double-ended screws according to claim 7, characterized in that: The heat exchange box (29) has an air inlet (33) and a second air outlet (34) on its side wall. The second air outlet (34) is connected to the air box (25) through a second suction pump (35).

9. The heat treatment apparatus for double-ended screws according to claim 1, characterized in that: The heating furnace body (1) is provided with a support frame (45) at both the left and right ends. Each support frame (45) is rotatably connected to two support rods (46). Each support rod (46) is fixedly fitted with a third sprocket (47). A third chain (48) is fitted between the two third sprockets (47) at the left and right ends of the heating furnace body (1). The third chain (48) is fixedly connected to the corresponding chain plate (6). A drive motor (49) is fixedly installed on one of the support frames (45). The output shaft of the drive motor (49) is coaxially fixedly connected to the corresponding support rod (46).

10. A heat treatment process for double-ended screws, using the heat treatment apparatus for double-ended screws according to claim 9, characterized in that: It includes the following steps: S1. Start the heating element (7) of the heating furnace body (1) to preheat the heating chamber (2) to the preset heat treatment temperature; at the same time, start the drive motor (49) to drive the conveyor belt (5) to circulate through the support rod (46), the third sprocket (47) and the third chain (48); S2. Insert the double-headed screw to be heat-treated into the feed port (3) of the heating furnace body (1), so that the middle bare rod part of the screw is embedded in the bolt placement space (11) formed between the placement part (10) of the adjacent rotating roller (9), and the screw enters the heating chamber (2) along with the chain plate (6). S3. When the chain plate (6) moves to the area of ​​the first rack (43), the first transmission gear (19) meshes with the first rack (43), and through the transmission of the first chain (18) and the first sprocket (17), all the rotating rollers (9) on the same chain plate (6) rotate synchronously, and the driving screw flips to achieve uniform heating. S4. Start the first suction pump (32) to extract the high-temperature oil mist and exhaust gas in the heating chamber (2) to the heat exchange box (29) coil (30) for heat exchange with cold air; start the second suction pump (35) to send the heated air after heat exchange into the air box (25), blow it out from the first air outlet (26) and pass through the chain plate (6) through the air passage (27) to act on the screw surface; S5. The rotating roller (9) drives the intermittent gear (44) to rotate synchronously. When its tooth surface meshes with the third rack (20), it pushes the first sliding rod (40) to slide, and drives the guide vane (37) to deflect through the transmission rod (41). When the smooth surface of the intermittent gear (44) is opposite to the third rack (20), the compression spring (42) pushes the sliding rod back, and the guide vane (37) resets, thus realizing the periodic change of the hot air direction. S6. When the chain plate (6) moves to the area of ​​the second rack (24) of the lower ring of the conveyor belt (5), the second transmission gear (23) meshes with the second rack (24), and drives all the rotating rods (13) on the same chain plate (6) to rotate synchronously through the second chain (22) and the second sprocket (21). The rolling steel ball (16) rolls in the placement cavity (15) and generates vibration, which is transmitted through the rotating roller (9) and cooperates with hot air to remove surface oil stains. S7. The high-temperature oil mist and exhaust gas after heat exchange in the heat exchange box (29) are transported to the external exhaust gas treatment device through the first suction pump (32) to meet the emission standards; S8. The screws that have completed heat treatment move with the chain plate (6) to the discharge port (4) or fall naturally in the turning area of ​​the conveyor belt (5) and are collected by the collection device.

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