A spheroidizing annealing furnace for high-strength bolt steel

Abstract

The application relates to the technical field of steel processing for field fasteners, in particular to a spheroidizing annealing furnace for processing high-strength bolt steel, which comprises a furnace body, a heat-conducting inner barrel arranged in the furnace body, a convection barrel distributed in the inner barrel, a heat-insulating and heat-preserving cylinder arranged in the outer part of the inner barrel, a resistance band, a plurality of vertical control units arranged in the outer part of the heat-insulating and heat-preserving cylinder, and a row of resistance rods driven by one side of each vertical control unit. The spheroidizing annealing furnace uses a plurality of resistance rods to limit and support the resistance band. The resistance rods avoid long-time contact with the locally heated resistance band through self-rotation. The accumulated heat at the contact position can be dissipated, so that the resistance band can be protected, and the aging speed of the resistance band is reduced.

Description

Technical Field

[0001] This invention relates to the field of fastener steel processing technology, specifically to a spheroidizing annealing furnace for processing high-strength bolt steel. Background Technology

[0002] A spheroidizing annealing furnace is a heat treatment device specifically designed to spheroidize steel. Its core purpose is to transform carbides in the steel into spherical shapes, thereby reducing hardness and increasing plasticity, facilitating subsequent steel processing. It is widely used in hardware manufacturing and special steel enterprises, and the treated material is more suitable for cold plastic deformation processes such as stamping and cold heading. The spheroidizing annealing furnace mainly consists of six core parts: the furnace body, heating system, strong convection circulation system, protective atmosphere system, control system, and cooling system.

[0003] Many low-temperature (≤1000℃) electrically heated spheroidizing annealing furnaces often use iron-chromium-aluminum or nickel-chromium alloy resistance bands as heating elements. After prolonged use, the resistance bands in spheroidizing annealing furnaces often experience localized low temperatures, which is a common type of failure in actual operation and directly affects the spheroidizing annealing process.

[0004] As the resistance bands are used for longer periods, surface oxidation increases their resistance, leading to a decrease in heating power and a slower localized heating rate. There are defects in the arrangement and structure of the resistance bands; the resistance bands in the middle of the furnace are more effective at heating than those at the top and bottom. The supporting system is also malfunctioning; the industrial temperature-measuring thermocouples are located in an inconvenient position within the annealing furnace, making it impossible to comprehensively monitor all radiative heat transfer areas of the resistance bands.

[0005] Localized low temperatures caused by resistance band failures in spheroidizing annealing furnaces can lead to incomplete spheroidization of workpieces, resulting in excessively high hardness and uneven internal composition in some workpieces, thus hindering subsequent quenching. The resistance band surrounds the heat-conducting inner barrel of the annealing furnace, transferring heat through the inner barrel to a convection cylinder. A support tray holds multiple high-strength bolts to be annealed within the convection cylinder. If the resistance band exhibits poor localized heating, the heat within the inner barrel cannot be evenly concentrated and impact the bolts, leading to poor spheroidizing annealing quality in some bolts. Furthermore, if the industrial thermocouple measuring the temperature happens to be located within the area of ​​normal resistance band heating, its nearby temperature measurement will show no abnormal values, while the problem of insufficient localized heat generation in distant areas of the resistance band, causing lower ambient temperatures, will go undetected. Therefore, a technology is urgently needed to perform localized temperature monitoring of each area of ​​the resistance band.

[0006] In traditional spheroidizing annealing furnaces, if there is a problem of insufficient localized heating of the resistance band, the entire resistance band is usually not replaced directly. Instead, the root cause of the fault is first investigated, and the entire resistance band is only replaced when it is confirmed that it is severely aged, the resistance value is generally drifting, or there are multiple irreparable damages. Additional temperature compensation technology can be used, where multiple heating elements are evenly distributed in the resistance band area. Since the heating elements themselves have limited heat generation, the resistance band is the main heat dissipation mechanism, continuously transferring heat to the inner barrel. When poor localized heating occurs in the resistance band, nearby heating elements generate heat, raising the surrounding temperature and bringing the ambient temperature to the normal range for localized heat dissipation by the resistance band. Therefore, this invention provides a spheroidizing annealing furnace for treating high-strength bolt steel. Summary of the Invention

[0007] The purpose of this invention is to provide a spheroidizing annealing furnace for treating high-strength bolt steel, so as to solve the problem of insufficient local heat generation in the resistance band mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a spheroidizing annealing furnace for treating high-strength bolt steel, comprising a furnace body, a furnace cover disposed above the furnace body, and a lifting arm connected above the furnace cover. The furnace body contains: an inner barrel for heat conduction, convection barrels distributed within the inner barrel, and a heat-insulating cylinder surrounding the inner barrel; multiple annular resistance strips arranged vertically, with a cylindrical cavity formed between the inner barrel and the heat-insulating cylinder to accommodate the resistance strips; multiple positive U-shaped segments and multiple inverted U-shaped segments arranged around the resistance strips, with the positive and inverted U-shaped segments alternating; a partial break in one part of the resistance strip, resulting in the beginning and end ends for external circuit connection; multiple vertical control units surrounding the heat-insulating cylinder, and a row of resistance rods driven on one side of each vertical control unit; a resistance rod for support distributed at the inner bend of each positive and inverted U-shaped segment.

[0009] The resistance rod comprises multiple uniformly arranged straight rod sections, which are connected end to end in pairs. The resistance rod dissipates heat to compensate for insufficient local heating of the resistance strip, and the resistance rod also avoids local heat accumulation in contact with the resistance strip by rotating.

[0010] The vertical control unit includes a unit column fixed on the inner wall of the outer shell cylinder of the furnace body, a thin cavity tube passing through a hole opened in the unit column, and a row of through-wall pipes connected to one side of the unit column. The through-wall pipes are movably sleeved in the radial holes opened in the heat insulation cylinder.

[0011] Multiple radial vent holes are evenly arranged around the narrow tube, and the multiple vent holes are distributed along the axial direction of the narrow tube. A row of small holes is opened on one side of the unit pile column. One end of the through-wall pipe is inserted into the circular groove opened on the unit pile column and communicates with one end of the small hole. The other end of the small hole meets and communicates with the surrounding vent holes.

[0012] The vertical control unit also includes a row of branch electrical components and a worm gear that drives a row of through-wall pipes. A worm wheel is fixed to the outside of the through-wall pipe to drive the worm gear, and the worm gear is installed on one side of the narrow cavity tube. Each through-wall pipe has a corresponding branch electrical component on its outside. The branch electrical component passes through the through-wall pipe and is electrically connected to both ends of the resistance rod. A gear is fixed to the bottom of the worm gear to mesh with a gear fixed to the bottom of the narrow cavity tube. An external gear ring is movably fitted on the outside of the heat insulation cylinder to drive the gear at the bottom of the worm gear. The bottom of the narrow cavity tube is a sealing column.

[0013] The vertical control unit also includes a heat extraction device that is connected to the top of the thin cavity tube, and an industrial thermocouple that measures the temperature of the airflow passing through the heat extraction device. An internal gear ring is provided on the inner wall of the outer shell to drive the heat extraction device.

[0014] The heat extraction device includes a diffuser movably sleeved on the top of the narrow tube, an exhaust pipe fixedly connected to one side of the diffuser vent, an impeller covering the top of the diffuser vent, an impeller shaft fixed above the impeller, and a sub-frame supporting the impeller shaft. One end of the sub-frame is fixed to the diffuser vent, and one end of the industrial thermocouple is inserted into the exhaust pipe.

[0015] One end of the exhaust pipe passes through the heat insulation cylinder and extends into the cylindrical cavity where the resistance strip is located. The impeller includes a disc body and multiple arc blades arranged vertically around one side of the disc body. The impeller shaft is movably sleeved in the shaft hole opened on the sub-frame, and a gear is set at the top of the impeller shaft to drive the internal gear ring.

[0016] The branch electrical component includes two rigid wires embedded in the through-wall pipe body, two metal springs encircling the outer wall of the through-wall pipe, two conductive rings sleeved on the outside of the through-wall pipe, an insulating horizontal plate for positioning and supporting the two conductive rings, and a flexible wire connected to one side of each insulating horizontal plate. One end of the flexible wire extends into the wire harness cavity opened on the unit pile column, and each metal spring corresponds to a conductive ring for contact and conduction.

[0017] One end of the rigid conductor is fixedly connected to the resistance rod, and the other end of the rigid conductor is fixedly connected to the metal spring. The conductive rings are distributed outside the heat insulation cylinder. One end of the insulating horizontal plate is fixed to the unit pile, and a protrusion is provided on one side of the conductive ring and embedded in the insulating horizontal plate.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the traditional spheroidizing annealing furnace for quenching fastener steel, the resistance strip is placed by multiple supports to limit the resistance strip. After the resistance strip is energized and heated, the contact parts between the supports and the resistance strip accumulate heat for a long time, which accelerates the aging of the resistance strip. The entire resistance strip needs to be replaced simply because of local overheating and severe aging. The annealing furnace is difficult to disassemble and reassemble, resulting in huge losses. The present invention uses multiple resistance rods to limit and support the resistance strip. The resistance rods avoid prolonged local contact with the heated resistance strip by rotating. The heat accumulated at the contact parts can be dissipated, which can protect the resistance strip and reduce the aging rate of the resistance strip.

[0019] 2. In this invention, each resistance rod has a corresponding exhaust port, which can specify the exhaust of air around any resistance rod. Then, the exhaust hot air is sampled and tested. If the detected temperature is within the specified range, the resistance rod does not need to be energized to heat up. If the detected temperature is below the specified range, the resistance rod can be energized to heat up. In this way, temperature compensation is used to make the temperature of all areas controlled by the entire resistance band uniform. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention.

[0021] Figure 2 This is a schematic diagram showing the location of the vertical control unit.

[0022] Figure 3 This is a diagram showing the location of the inner tub.

[0023] Figure 4 This is a schematic diagram showing the position of the resistor band.

[0024] Figure 5 This is a schematic diagram showing the position of the resistance rod.

[0025] Figure 6 This is a schematic diagram of the resistor band structure.

[0026] Figure 7 This is a schematic diagram of a resistance rod structure.

[0027] Figure 8 This is a schematic diagram of a unit pile column structure.

[0028] Figure 9 This is a schematic diagram of a thin-cavity tube structure.

[0029] Figure 10 This is a schematic diagram of the small hole structure.

[0030] Figure 11 This is a schematic diagram showing the location of the branch electrical components.

[0031] Figure 12 This is a schematic diagram of a worm gear structure.

[0032] Figure 13 This is a schematic diagram showing the position of the resistance rod.

[0033] Figure 14 This is a schematic diagram of the branch electrical components.

[0034] Figure 15 This is a schematic diagram showing the position of the external gear ring.

[0035] Figure 16 This is a schematic diagram of the heat extraction device.

[0036] Figure 17 This is a schematic diagram of the impeller structure.

[0037] Figure 18 This is a schematic diagram showing the location of the pipe that passes through the wall.

[0038] In the diagram: Furnace body 1, outer shell cylinder 101, furnace cover 2, boom 3, inner barrel 4, convection barrel 5, heat insulation cylinder 6, resistance band 7, positive U-shaped section 701, inverted U-shaped section 702, vertical control unit 8, resistance rod 9, unit post 10, thin cavity tube 11, exhaust hole 111, small hole 112, wall penetration pipe 12, branch electrical components 13, flexible wire 131, insulating horizontal plate 132, conductive ring 133, rigid wire 134, metal spring 135, wire harness cavity 136, worm gear 14, external gear ring 15, heat extraction device 16, impeller shaft 161, impeller 162, sub-frame 163, exhaust pipe 164, air diffuser 165, industrial thermocouple 17, internal gear ring 18. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the technical solutions of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figures 1 to 18 This invention provides a technical solution: a spheroidizing annealing furnace for treating high-strength bolt steel, comprising a furnace body 1, a furnace cover 2 disposed above the furnace body 1, and a lifting arm 3 connected above the furnace cover 2. The furnace body 1 contains: The inner barrel 4 is used for heat conduction, the convection barrel 5 is distributed in the inner barrel 4, and the heat insulation cylinder 6 is arranged around the outside of the inner barrel 4. The core material of the heat insulation cylinder 6 can be aluminum silicate refractory fiber, or composite ultra-lightweight refractory brick or perlite insulation brick. Multiple materials are tightly filled in the shell of the heat-resistant alloy cylinder to form a composite structure of metal cylinder and refractory lining. Multiple annular resistance bands 7 are arranged vertically. In actual equipment, the number of resistance bands 7 arranged from top to bottom is at least 10. A cylindrical cavity for accommodating the resistance bands 7 is formed between the inner barrel 4 and the heat insulation cylinder 6. Multiple positive U-shaped segments 701 and multiple inverted U-shaped segments 702 are arranged around the resistance bands 7, and the positive U-shaped segments 701 and inverted U-shaped segments 702 are alternately distributed. In this embodiment, the number of positive U-shaped segments 701 and inverted U-shaped segments 702 on a single resistance band 7 is at least 20. A partial break is made on the resistance band 7, and the resulting end is used for external circuit connection. A main power supply line is laid on the spheroidizing annealing furnace. One end of the main power supply line is connected to an external power source, and the other end is laid along the outer wall of the heat insulation cylinder 6 and extends to the vicinity of the end of the resistance band 7. Then, it passes through the heat insulation cylinder 6 to be electrically connected to the end of the resistance band 7 to control the resistance band 7 to be energized and heated. Multiple vertical control units 8 are arranged around the outside of the heat insulation cylinder 6. In specific implementation, the vertical control units 8 are set according to the position and number of the positive U-shaped segments 701 and the inverted U-shaped segments 702 on the resistor strip 7. Specifically, one vertical control unit 8 is corresponding to one positive U-shaped segment 701 in the same vertical direction, and one vertical control unit 8 is also corresponding to one inverted U-shaped segment 702 in the same vertical direction. A row of resistor rods 9 is driven on one side of each vertical control unit 8, and a resistor rod 9 for support is distributed at the inner bend of each positive U-shaped segment 701 and inverted U-shaped segment 702.

[0041] Reference Appendix Figure 6 With the upper and lower resistance bars 9 limiting the movement, the resistance band 7 cannot move up or down. In addition, multiple resistance bars 9 are evenly arranged around the resistance band 7. When the resistance band 7 moves radially in any direction in the horizontal direction, it will be blocked by the resistance bars 9 that are perpendicular to the radial direction. In this way, the resistance band 7 achieves spatial positioning, and the heat generated by the resistance band 7 is evenly diffused into the internal heat insulation cylinder 6.

[0042] Reference Appendix Figure 7 It is understood that the resistance rod 9 includes multiple uniformly arranged straight rod sections, which are connected end to end in pairs. The resistance rod 9 dissipates heat to compensate for insufficient local heating of the resistance strip 7, and the resistance rod 9 also avoids local heat accumulation in contact with the resistance strip 7 by rotating itself.

[0043] In traditional spheroidizing annealing furnaces, when the resistance strip is laid out, a support is installed at the bend of the resistance strip. However, the support is fixed, so the resistance strip heats up for a long time, and heat accumulates at the contact point between the support and the resistance strip. Over time, this will accelerate the aging and damage of the resistance strip. Therefore, this invention eliminates the problem of local heat accumulation in the resistance strip by rotating the resistance rod 9, so that the heat accumulated at the contact point can be dissipated.

[0044] Reference Appendix Figure 11The vertical control unit 8 includes a unit column 10 fixed on the inner wall of the outer shell cylinder 101 on the furnace body 1, a thin cavity tube 11 passing through a hole in the unit column 10, and a row of through-wall pipes 12 connected to one side of the unit column 10. The through-wall pipes 12 are movably fitted into the radial holes opened on the heat insulation cylinder 6. Multiple retaining rings can be fixedly fitted on the outer wall of the waist of the through-wall pipe 12. The retaining rings are engaged in the annular grooves opened on the inner wall of the radial holes of the heat insulation cylinder 6. In this way, the through-wall pipe 12 rotates in place on the heat insulation cylinder 6. The retaining rings on the through-wall pipe 12 can also improve the heat insulation and sealing performance inside the heat insulation cylinder 6.

[0045] Reference Appendix Figure 9 and attached Figure 10 It is understood that multiple radial vent holes 111 are evenly arranged around the narrow cavity tube 11, and the multiple vent holes 111 are distributed along the axial direction of the narrow cavity tube 11. A row of small holes 112 is opened on one side of the unit pile column 10. One end of the through-wall tube 12 is inserted into the circular groove opened on the unit pile column 10 and communicates with one end of the small hole 112. The other end of the small hole 112 meets and communicates with the surrounding vent holes 111.

[0046] The thin-cavity tube 11 controls the connection between the exhaust holes 111 at different heights and the corresponding horizontal small holes 112 by rotating. Only one exhaust hole 111 on a single thin-cavity tube 11 is connected to the outside at any time. In this way, the hot air inside the heat insulation cylinder 6 is extracted through the wall-penetrating pipe 12, and then enters the only connected exhaust hole 111 through the small hole 112. Subsequently, it rises through the central axial cavity of the thin-cavity tube 11. This design can accurately control the collection of hot air near any local area of ​​the resistance band 7, and then determine whether the local area of ​​the resistance band 7 is heating normally by detecting the temperature of the hot air in that area. If the temperature is lower than the specified range, the temperature compensation mechanism will be automatically triggered, that is, the resistance rod 9 in the low-temperature area will be energized to heat up and supplement the heat.

[0047] Reference Appendix Figure 11 and attached Figure 12The vertical control unit 8 also includes a row of branch electrical components 13 and a worm gear 14 that drives a row of through-wall pipes 12. A worm wheel is fixed to the outside of the through-wall pipe 12 to drive the worm gear 14, and the worm gear 14 is installed on one side of the narrow cavity pipe 11. Each through-wall pipe 12 has a corresponding branch electrical component 13 fitted on its outside. The branch electrical component 13 passes through the through-wall pipe 12 and is electrically connected to both ends of the resistance rod 9. A gear is fixed at the bottom of the worm gear 14 to mesh with a gear fixed at the bottom of the narrow cavity pipe 11. An external gear ring 15 is movably fitted on the outside of the heat insulation cylinder 6 to engage with the gear at the bottom of the worm gear 14. The gear transmission is used. The bottom end of the thin cavity tube 11 is a sealing column. The thin cavity tube 11 is movably sleeved in the vertical hole of the unit pile column 10. The thin cavity tube 11 rotates in the unit pile column 10. The outer gear ring 15 is inserted into the annular groove opened on the outer side wall of the heat insulation cylinder 6. A small servo motor can be installed at the bottom of the furnace to drive the outer gear ring 15 to rotate, causing all the worm gears 14 to rotate, and then the thin cavity tube 11 rotates. After the single exhaust hole 111 on the thin cavity tube 11 is connected to the stationary small hole 112, the thin cavity tube 11 stops rotating, and the subsequent gas extraction and temperature measurement work can be carried out.

[0048] Reference Appendix Figure 11 The vertical control unit 8 also includes a heat extraction device 16 that is connected to the top of the thin cavity tube 11, and an industrial thermocouple 17 that measures the temperature of the airflow passing through the heat extraction device 16. An internal gear ring 18 is provided on the inner wall of the outer shell cylinder 101 to drive the heat extraction device 16. An annular groove is opened on the inner wall of the outer shell cylinder 101, and the internal gear ring 18 is inserted into the annular groove. The rotation of the internal gear ring 18 drives all the heat extraction devices 16. A servo motor can be installed on one side of the top of the furnace body 1, and a linkage shaft group can be established between the servo motor and the internal gear ring 18 to realize the control of the rotation and stopping of the internal gear ring 18.

[0049] The heat extraction device 16 includes a diffuser 165 movably sleeved on the top of the narrow tube 11, an exhaust pipe 164 fixedly connected to one side of the diffuser 165, an impeller 162 covering the top of the diffuser 165, an impeller shaft 161 fixed above the impeller 162, and a sub-frame 163 supporting the impeller shaft 161. One end of the sub-frame 163 is fixed to the diffuser 165, and one end of the industrial thermocouple 17 is inserted into the exhaust pipe 164.

[0050] One end of the exhaust pipe 164 passes through the heat insulation cylinder 6 and extends into the cylindrical cavity where the resistance band 7 is located. The impeller 162 includes a disc body and multiple arc blades vertically arranged around one side of the disc body. The impeller shaft 161 is movably sleeved in the shaft hole opened on the sub-frame 163, and a gear is provided at the top of the impeller shaft 161 to drive the internal gear ring 18.

[0051] The internal gear ring 18 rotates to drive all the impeller shafts 161. The impeller shafts 161 drive the impellers 162 to rotate, providing power for the gas delivery in the diffuser 165. That is, the air around a local area on the resistor strip 7 is extracted, sucked into the narrow cavity tube 11 through the nearest through-wall pipe 12, rises in the narrow cavity tube 11, and is then sucked into the diffuser 165. It then returns to the cylindrical cavity where the resistor strip 7 is located through the exhaust pipe 164. The industrial thermocouple 17 detects the temperature of the hot air passing through the exhaust pipe 164. The detected hot air flows back into the space where the resistor strip 7 is located instead of being directly discharged, which can avoid energy waste. In this invention, multiple industrial thermocouples 17 arranged in a ring are used to quickly sample and detect the local air at various points on the resistor strip 7.

[0052] Branch electrical component 13 includes two rigid wires 134 embedded in the through-wall pipe 12, two metal springs 135 encircling the outer wall of the through-wall pipe 12, two conductive rings 133 sleeved on the outside of the through-wall pipe 12, an insulating horizontal plate 132 for positioning and supporting the two conductive rings 133, and a flexible wire 131 correspondingly connected to one side of each insulating horizontal plate 132. One end of the flexible wire 131 extends into the wire harness cavity 136 opened on the unit post 10. Each metal spring 135 corresponds to one conductive ring 133 for contact and conduction. Figure 14 The two metal springs 135 are not on the same surrounding surface. As mentioned earlier, the resistance rod 9 changes its contact point with the resistance strip 7 by rotating, preventing the contact point on the resistance strip 7 from accumulating heat over time and causing the resistance strip 7 to age faster. The driving process of the resistance rod 9 is as follows: the outer gear ring 15 rotates to drive the worm gear 14, the worm gear 14 rotates to drive the through-wall tube 12, the through-wall tube 12 drives the rigid wire 134, and thus drives the resistance rod 9 to rotate. During the rotation of the resistance rod 9, the power supply circuit is stably maintained. The specific circuit path is from a flexible wire 131 to a conductive ring 133 that is electrically connected, then through a contacting metal spring 135 to a rigid wire 134, then the current passes through the resistance rod 9 to another rigid wire 134, then through another metal spring 135 to another conductive ring 133, and then leaves through another flexible wire 131. Although the through-wall tube 12 drives the metal spring 135 to rotate, the conductive ring 133 and the metal spring 135 always maintain contact and conduction.

[0053] One end of the rigid wire 134 is fixedly connected to the resistance rod 9, and the other end of the rigid wire 134 is fixedly connected to the metal spring 135. The conductive rings 133 are distributed outside the heat insulation cylinder 6. One end of the insulating horizontal plate 132 is fixed on the unit pile 10, and a protrusion is provided on one side of the conductive ring 133 and embedded in the insulating horizontal plate 132.

[0054] Reference Appendix Figure 14Understandably, in this embodiment, the metal spring 135 is an arc-shaped U-shaped spring. The soft wire 131 extending into the wire harness cavity 136 can extend downward along the cavity and finally connect to the temperature control system installed at the bottom of the furnace. The temperature control system can independently control the heating of each resistance rod 9, and can change the heating intensity of the control resistance rod 9 by changing the current intensity. In this way, the resistance rod 9 can accurately compensate for the local lack of heat in the resistance band 7.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A spheroidizing annealing furnace for treating high-strength bolt steel, characterized in that: The furnace includes a furnace body, a furnace cover mounted on top of the furnace body, and a lifting arm connected to the top of the furnace cover. The furnace body contains: The inner barrel for heat conduction, the convection barrels distributed in the inner barrel, and the heat insulation cylinder surrounding the outside of the inner barrel. Multiple ring-shaped resistance strips are arranged vertically. A cylindrical cavity is formed between the inner barrel and the heat insulation cylinder to accommodate the resistance strips. The resistance strips are provided with multiple positive U-shaped segments and multiple inverted U-shaped segments, and the positive U-shaped segments and inverted U-shaped segments are distributed alternately. There is a partial break on the resistance strip, and the resulting start and end ends are used for external circuits. Multiple vertical control units are arranged around the outside of the heat insulation cylinder, and a row of resistance rods driven on one side of each vertical control unit. A resistance rod for support is distributed at the inner bend of each positive U-shaped segment and inverted U-shaped segment. The resistance rod comprises multiple uniformly arranged straight rod sections, which are connected end to end in pairs. The resistance rod dissipates heat to compensate for insufficient local heating of the resistance strip, and the resistance rod also avoids local heat accumulation in contact with the resistance strip by rotating.

2. The spheroidizing annealing furnace for treating high-strength bolt steel according to claim 1, characterized in that: The vertical control unit includes a unit column fixed on the inner wall of the outer shell cylinder of the furnace body, a thin cavity tube passing through a hole opened in the unit column, and a row of through-wall pipes connected to one side of the unit column. The through-wall pipes are movably sleeved in the radial holes opened in the heat insulation cylinder.

3. The spheroidizing annealing furnace for treating high-strength bolt steel according to claim 2, characterized in that: Multiple radial vent holes are evenly arranged around the narrow tube, and the multiple vent holes are distributed along the axial direction of the narrow tube. A row of small holes is opened on one side of the unit pile column. One end of the through-wall pipe is inserted into the circular groove opened on the unit pile column and communicates with one end of the small hole. The other end of the small hole meets and communicates with the surrounding vent holes.

4. The spheroidizing annealing furnace for treating high-strength bolt steel according to claim 2, characterized in that: The vertical control unit also includes a row of branch electrical components and a worm gear that drives a row of through-wall pipes. A worm wheel is fixed to the outside of the through-wall pipe to drive the worm gear, and the worm gear is installed on one side of the narrow cavity tube. Each through-wall pipe has a corresponding branch electrical component on its outside. The branch electrical component passes through the through-wall pipe and is electrically connected to both ends of the resistance rod. A gear is fixed to the bottom of the worm gear to mesh with a gear fixed to the bottom of the narrow cavity tube. An external gear ring is movably fitted on the outside of the heat insulation cylinder to drive the gear at the bottom of the worm gear. The bottom of the narrow cavity tube is a sealing column.

5. A spheroidizing annealing furnace for treating high-strength bolt steel according to claim 2, characterized in that: The vertical control unit also includes a heat extraction device that is connected to the top of the thin cavity tube, and an industrial thermocouple that measures the temperature of the airflow passing through the heat extraction device. An internal gear ring is provided on the inner wall of the outer shell to drive the heat extraction device.

6. The spheroidizing annealing furnace for treating high-strength bolt steel according to claim 5, characterized in that: The heat extraction device includes a diffuser movably sleeved on the top of the narrow tube, an exhaust pipe fixedly connected to one side of the diffuser vent, an impeller covering the top of the diffuser vent, an impeller shaft fixed above the impeller, and a sub-frame supporting the impeller shaft. One end of the sub-frame is fixed to the diffuser vent, and one end of the industrial thermocouple is inserted into the exhaust pipe.

7. A spheroidizing annealing furnace for treating high-strength bolt steel according to claim 6, characterized in that: One end of the exhaust pipe passes through the heat insulation cylinder and extends into the cylindrical cavity where the resistance strip is located. The impeller includes a disc body and multiple arc blades arranged vertically around one side of the disc body. The impeller shaft is movably sleeved in the shaft hole opened on the sub-frame, and a gear is set at the top of the impeller shaft to drive the internal gear ring.

8. A spheroidizing annealing furnace for treating high-strength bolt steel according to claim 4, characterized in that: The branch electrical component includes two rigid wires embedded in the through-wall pipe body, two metal springs encircling the outer wall of the through-wall pipe, two conductive rings sleeved on the outside of the through-wall pipe, an insulating horizontal plate for positioning and supporting the two conductive rings, and a flexible wire connected to one side of each insulating horizontal plate. One end of the flexible wire extends into the wire harness cavity opened on the unit pile column, and each metal spring corresponds to a conductive ring for contact and conduction.

9. A spheroidizing annealing furnace for treating high-strength bolt steel according to claim 8, characterized in that: One end of the rigid conductor is fixedly connected to the resistance rod, and the other end of the rigid conductor is fixedly connected to the metal spring. The conductive rings are distributed outside the heat insulation cylinder. One end of the insulating horizontal plate is fixed to the unit pile, and a protrusion is provided on one side of the conductive ring and embedded in the insulating horizontal plate.

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