Energy-saving mesh belt quenching furnace

Abstract

The energy-saving type mesh belt quenching furnace comprises a conveying mesh belt used for conveying workpieces in a hearth, a preheating unit and a fine heating unit, the preheating unit and the fine heating unit are used for conducting primary heating and secondary heating on the workpieces respectively, the preheating unit comprises a first heating body and a first heat exchange pipe, and the positions of the first heating body and the first heat exchange pipe can be adjusted along the conveying mesh belt. The fine heating unit comprises a height-adjustable second heating body and a second heat exchange pipe, a circulation loop is formed between the two heat exchange pipes, a heat adjusting pump is arranged between the two heat exchange pipes, a compound heat preservation structure and a furnace base are arranged at the bottom of the furnace body, the compound heat preservation structure comprises a plurality of heat preservation layers which are sequentially arranged from inside to outside, and the compressive strength and the heat conductivity coefficient of the heat preservation layers are gradually reduced; the furnace base comprises supporting channel steel forming a framework, phenolic plastic parts arranged between the supporting channel steel and thermal insulation materials filled in the framework. According to the invention, internal circulation of heat energy is realized, the heating temperature of the workpiece is accurately controlled, the heat loss of the furnace bottom is reduced, the quenching quality of the small workpiece is improved, and the aim of saving energy is fulfilled.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment furnaces, and in particular to an energy-saving mesh belt quenching furnace. Background Art

[0002] The mesh belt quenching furnace is a continuous automatic control heat treatment furnace. It uses a conveyor mesh belt driven by an intermittent forward mechanism to transport the workpiece. After passing through the heating zone with precise temperature control, the workpiece falls into the quenching tank and is taken out by the elevator. The mesh belt quenching furnace is suitable for mass production of small and medium-sized mechanical parts, such as high-strength fasteners, bearings, hardware tools, etc., and performs heat treatments such as carburizing, carbonitriding, and quenching in a controlled atmosphere. Since the power consumption of the heat treatment operation of the mesh belt quenching furnace accounts for about 65% of the total power consumption of mechanical parts manufacturing, how to achieve energy saving effects during the operation of the mesh belt quenching furnace has received much attention in the industry.

[0003] The current mesh belt quenching furnace mostly adopts a single-stage heating method, which is not convenient for precise adjustment of the heating temperature of the workpiece. Therefore, it cannot be used for the processing of small workpieces with high requirements for quenching temperature accuracy. In addition, when adjusting the temperature of the mesh belt quenching furnace, technicians will export the excess heat energy in the furnace for secondary use, such as transferring heat to other equipment for operation or for adjusting the indoor temperature through a heat circulation pipe. Although this method does improve the efficiency of heat energy utilization and reduce heat energy loss from a certain perspective, this method of heat energy utilization cannot be used to improve the thermal efficiency of workpiece processing in the quenching furnace, and there will be damage during the heat transfer process, and there are many restrictions on external environmental conditions.

[0004] The important indicators of the energy-saving effect of the reaction belt quenching furnace are parameters such as surface temperature rise and empty furnace energy consumption. The corresponding test methods are specified in the national standard "Test Methods for Electric Heating Equipment Part 4: Indirect Resistance Furnace", and the industry standard "Technical Requirements for Heat Treatment of Belt Quenching Furnace Production Line" (JB / T10897-2008) has surface temperature rise requirements and power consumption indicators for belt quenching furnaces, such as furnace shell surface temperature rise ≦55℃. In addition, the furnace shell does not include the furnace bottom. The energy-saving design for the furnace bottom is often easily overlooked in the production process of the belt quenching furnace, and is also easily overlooked in various standards. Summary of the invention

[0005] Based on this, the present invention provides an energy-saving mesh belt quenching furnace, which realizes the internal circulation of heat energy in the furnace and the precise adjustment of the heating temperature of the workpiece by using the excess heat in the secondary heating process for the initial heating of the workpiece, which is beneficial to improving the quenching quality of small workpieces, and further cooperates with the improvement of the thermal insulation structure of the furnace bottom to achieve the purpose of energy saving.

[0006] In order to achieve the above-mentioned object, the present invention provides an energy-saving mesh belt quenching furnace, comprising a preheating unit, a fine heating unit, a workpiece conveying unit and a heating control unit; The workpiece conveying unit includes a conveyor mesh belt for carrying and conveying the workpiece to move forward in the furnace and a rotating mechanism for driving the conveyor mesh belt; The preheating unit is arranged in the furnace and upstream of the conveyor mesh belt, and is used for performing initial heating on the workpiece. The preheating unit includes a first heating body and a first heat exchange tube; The fine heating unit is arranged in the furnace and downstream of the conveyor mesh belt, and is used for performing secondary heating on the workpiece after the initial heating. The fine heating unit comprises a second heating body and a second heat exchange tube. The heating temperature of the second heating body is higher than that of the first heating body. The second heat exchange tube is connected with the first heat exchange tube to form a circulation loop, and a heat regulating pump is arranged between the two heat exchange tubes. There are multiple temperature sensors arranged at various locations in the furnace, and used to monitor the temperature of the workpiece during initial heating, secondary heating and when leaving the furnace; The heating control unit is electrically connected to the workpiece conveying unit, pre-heating unit, fine heating unit, and heat regulating pump and is independently controlled. The heating control unit is configured to keep the temperature of the workpiece when it leaves the furnace within a set range by at least controlling the moving speed of the conveyor belt, the heating temperature of each heating body, and the opening of the heat regulating pump based on the signal fed back by the temperature sensor.

[0007] Furthermore, the fine heating unit also includes a second heating frame and a lifting mechanism arranged above the conveyor mesh belt, the second heating body is fixedly arranged on the lower surface of the second heating frame, the lifting mechanism is used to drive the second heating frame to move closer to or away from the conveyor mesh belt, and the heating control unit is electrically connected to the lifting mechanism and is configured to control the action of the lifting mechanism according to the signal feedback from the temperature sensor to adjust the height of the second heating frame.

[0008] Furthermore, the preheating unit also includes a first heating frame and a horizontal moving mechanism arranged under the conveyor mesh belt, the first heating frame is used to carry the first heating body, the horizontal moving mechanism is used to drive the first heating frame to move along the conveyor mesh belt, and the heating control unit is electrically connected to the horizontal moving mechanism, and is configured to control the movement of the horizontal moving mechanism according to the signal feedback from the temperature sensor to adjust the position of the first heating frame.

[0009] Furthermore, the preheating unit also includes a cooling fan arranged at the bottom of the first heating rack, and the heating control unit is electrically connected to the cooling fan and is configured to adjust the rotation speed of the cooling fan according to a signal fed back by the temperature sensor.

[0010] Furthermore, a composite thermal insulation structure is arranged at the bottom of the furnace body, and a steel plate is arranged at the bottom of the composite thermal insulation structure. The composite thermal insulation structure includes a plurality of thermal insulation layers which are arranged in sequence from the inside to the outside and whose compressive strength and thermal conductivity coefficient gradually decrease. The thermal insulation layer adopts at least one of thermal insulation bricks, ceramic fiber materials, nano thermal insulation materials or nano thermal insulation coatings.

[0011] Furthermore, the duplex insulation structure includes a first insulation layer, a second insulation layer and a third insulation layer arranged in sequence from the inside to the outside, the first insulation layer and the second insulation layer are both insulation bricks, and the third insulation layer is a ceramic fiberboard.

[0012] Furthermore, it also includes a furnace base for supporting the entire furnace body, the furnace base includes supporting channel steels and phenolic plastic parts, a plurality of the supporting channel steels are spliced ​​to form the skeleton of the furnace base, the phenolic plastic parts are arranged between the supporting channel steels and are detachably fastened to adjacent supporting channel steels, and the furnace base skeleton is filled with at least one of ceramic fiber materials, nano thermal insulation materials or nano thermal insulation coatings.

[0013] Furthermore, a ceramic fiber blanket is filled in the furnace base frame, a rock wool board is laid on the bottom of the ceramic fiber blanket, and a ceramic fiber board is laid outside the furnace base frame.

[0014] The present invention has at least the following technical advantages: The present invention establishes a heat circulation loop between the preheating unit and the fine heating unit through a heat regulating pump, transmits the excess heat in the temperature regulating process of the fine heating unit to the preheating unit, and assists the first heating body in the preheating unit to perform the initial heating of the workpiece, which not only realizes the recycling of heat energy in the furnace and reduces the energy loss in the processing process, but also can timely control the heating temperature of the workpiece in the fine heating unit through the circulation, improves the speed and accuracy of temperature regulation, ensures the balance of the heating process, and thus improves the quenching quality and efficiency of small workpieces; 2. The present invention can adjust the horizontal position of the pre-heating unit along the conveyor belt, thereby realizing supplementary heating of some workpieces with low temperature and improving heating uniformity; the fine heating unit can adjust the height position to realize rapid adjustment of the secondary heating temperature of the workpiece, thereby achieving the purpose of fine adjustment of the temperature of the workpiece when it is out of the furnace, avoiding the problem of unstable quenching quality of the workpiece due to insufficient heating temperature or excessive heating temperature, and improving the quality and efficiency of quenching heating.

[0015] 3. The present invention can effectively reduce heat loss by arranging a composite insulation structure with compressive strength and thermal conductivity coefficient decreasing layer by layer at the bottom of the quenching furnace; by arranging a furnace base combining phenolic plastic parts and supporting channel steel to support the furnace body, the thermal bridge phenomenon is reduced, and the heat loss from the furnace bottom to the ground is reduced, thereby achieving the purpose of energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 2 is a schematic structural diagram of an energy-saving mesh belt quenching furnace provided according to an embodiment of the present invention (the furnace wall structure is not shown); Figure 2 This is a control principle diagram of an energy-saving mesh belt quenching furnace provided according to an embodiment of the present invention; Figure 3 yes Figure 1 A schematic structural diagram of the first heating unit; Figure 4 yes Figure 1 A schematic structural diagram of the second heating unit; Figure 5 yes Figure 1 A schematic diagram of the structure of the circulation loop formed by the preheating unit and the fine heating unit; Figure 6 yes Figure 1 Sectional view along AA direction; In the figure: 1-preheating unit, 11-first heating rack, 12-first heating body, 13-first heat exchange tube, 14-cooling fan, 15-horizontal moving mechanism; 2-fine heating unit, 21-second heating frame, 22-second heating body, 23-second heat exchange tube, 24-lifting mechanism; 3-workpiece conveying unit, 31-conveying mesh belt, 32-rotating mechanism; 4- Heating control unit; 51-furnace, 52-insulation board, 53-first insulation layer, 54-second insulation layer, 55-third insulation layer, 56-support channel steel, 57-phenolic plastic parts, 58-ceramic fiber blanket, 59-rock wool board; 6-Workpiece; 7-Heat regulating pump; 8- Temperature sensor.

[0018] It should be understood that the size of each part shown in the accompanying drawings is not drawn according to the actual proportional relationship. In addition, the same or similar reference numerals represent the same or similar components. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without carrying out creative work are within the scope of protection of the present invention.

[0020] Embodiment 1

[0021] like Figure 1 , Figure 2 and Figure 5 As shown, an energy-saving mesh belt quenching furnace includes a preheating unit 1, a fine heating unit 2, a workpiece conveying unit 3, a heating control unit 4 and a temperature sensor 8.

[0022] The workpiece conveying unit 3 includes a conveyor mesh belt 31 for carrying and conveying the workpiece 6 forward in the furnace 51 and a rotating mechanism 32 for driving the conveyor mesh belt 31; the preheating unit 1 is arranged in the furnace 51 and located upstream of the conveyor mesh belt 31, and is used for initial heating of the workpiece 6; the fine heating unit 2 is arranged in the furnace 51 and located downstream of the conveyor mesh belt 31, and is used for secondary heating of the workpiece 6 after initial heating. A vertical insulation board 52 is arranged in the furnace 51 to separate the areas where the preheating unit 1 and the fine heating unit 2 are located. The insulation board 52 is perpendicular to the conveying direction of the conveyor mesh belt 31, and a gap is provided at the bottom of the insulation board 52 for the conveyor mesh belt 31 to pass through.

[0023] The preheating unit 1 includes a first heating body 12 and a first heat exchange tube 13 arranged in the first heating body 12. The fine heating unit 2 includes a second heating body 22 and a second heat exchange tube 23 arranged in the second heating body 22. The heating temperature of the second heating body 22 is higher than that of the first heating body 12. The second heat exchange tube 23 is connected to the first heat exchange tube 13 to form a circulation loop. A heat regulating pump 7 is arranged between the two heat exchange tubes.

[0024] There are multiple temperature sensors 8 arranged at various locations in the furnace 51. Specifically, a temperature sensor 8 is set near the pre-heating unit 1 to monitor the temperature of the workpiece 6 during the initial heating, a temperature sensor 8 is set near the fine heating unit 2 to monitor the temperature of the workpiece 6 during the secondary heating, and a temperature sensor 8 is set near the exit of the furnace 51 to monitor the temperature of the workpiece 6 when it leaves the furnace 51.

[0025] The heating control unit 4 is electrically connected to the workpiece conveying unit 3, the preheating unit 1, the fine heating unit 2, and the heat regulating pump 7 and is independently controlled. The heating control unit 4 is configured to keep the temperature of the workpiece 6 within a set range when it leaves the furnace 51 by at least controlling the moving speed of the conveyor belt, the heating temperature of each heating body, and the opening of the heat regulating pump according to the signal fed back by the temperature sensor 8.

[0026] The length of the conveyor mesh belt 31 in the pre-heating unit 1 is greater than its length in the fine heating unit 2, and the heating area covered by the first heating body 12 on the conveyor mesh belt 31 is greater than the heating area covered by the second heating body 22 on the conveyor mesh belt 31.

[0027] The energy-saving mesh belt quenching furnace also includes a furnace body, a furnace seat, a heat preservation structure, a heating element, etc. The furnace body is composed of a box body and a bracket, which are all made of high-quality steel and steel plates by welding. In order to facilitate the operator to inspect and clean the furnace, the furnace body is designed as an upper and lower split structure, and the furnace cover can be removed. The furnace of the furnace body adopts a full fiber composite structure with excellent heat preservation performance. Aluminum silicate fiber felt is used on the furnace top and both sides of the furnace, which can be disassembled and assembled as a whole with the furnace cover, and has excellent heat preservation performance, which saves more than 40% energy than the brick lining. The heating element is wound with high-quality resistance wire, horizontally inserted into the furnace from one side of the furnace body, and arranged at the upper and lower positions of the heating body. The heating element is reliable in use and easy to maintain. When necessary, it can be replaced in a hot state without stopping the furnace.

[0028] When the quenching furnace in this embodiment is in use, the workpiece 6 is placed in the area where the conveyor belt 31 is located outside the feeding port of the quenching furnace, and the workpiece 6 is driven forward by the rotating mechanism 32 to enter the furnace chamber 51. The workpiece 6 is first heated by the preheating unit 1, and then heated by the fine heating unit 2 to reach the preset process temperature range. During the entire heating process, the excess heat of the fine heating unit 2 is transported to the preheating unit 1 through the circulation loop formed by the heat exchange tube, to assist in the preheating of the workpiece 6, thereby realizing the internal recycling of heat energy, improving the adjustment speed and accuracy of the fine heating temperature, and avoiding the problem of unstable quenching quality caused by insufficient heating temperature or excessive heating temperature, so that the quenching furnace is suitable for the processing requirements of small workpieces with high quenching temperature control requirements, thereby improving the stability of workpiece production quality.

[0029] Embodiment 2

[0030] At present, the furnace bottom of the common mesh belt quenching furnace usually adopts an overhead structure. The overhead height varies depending on the manufacturer and the size of the furnace, mostly between 150-400mm. The mesh belt quenching furnace is manufactured with the bottom surface of the furnace body as the reference surface. First, it is made of steel overhead, that is, a furnace base is built with channel steel, and a steel plate is laid on the base. The steel plate is built with a refractory material to form an insulation layer to form the furnace bottom. The thickness of the insulation layer at the bottom of the furnace is less than that of the furnace wall and the top of the furnace, and the heat energy is transferred to the furnace bottom steel plate through the insulation layer. According to research, the surface temperature rise of the furnace bottom of the new furnace basically reaches above 85℃, and some even reach above 120℃. The surface temperature rise of the furnace bottom of the furnace that has been used for a period of time may reach above 140℃. Part of the heat energy is dissipated in the air, so that the air temperature between the channel steel and the ground can reach above 80℃. Due to the thermal bridge effect of the channel steel, another part of the heat energy is directly transferred to the ground, and the temperature of the ground under the furnace bottom can reach above 45℃. Such a high temperature rise brings serious energy waste.

[0031] To this end, this embodiment makes structural improvements on the insulation layer and the furnace seat at the furnace bottom, as follows: Improvement of furnace bottom insulation layer: A composite thermal insulation structure is arranged at the bottom of the furnace body, and a steel plate is arranged at the bottom of the composite thermal insulation structure. The composite thermal insulation structure includes a plurality of thermal insulation layers which are arranged in sequence from the inside to the outside and whose compressive strength and thermal conductivity coefficient decrease layer by layer. The thermal insulation layers are made of at least one of thermal insulation bricks, ceramic fiber materials, nano thermal insulation materials or nano thermal insulation coatings.

[0032] In this embodiment, the total thickness of the composite insulation structure is 278 mm, including the first insulation layer 53, the second insulation layer 54 and the third insulation layer 55 arranged from the inside to the outside. The first insulation layer 53 adopts vertical insulation bricks with a thickness of 114 mm, a compressive strength of 5.7 MPa and a thermal conductivity of 0.6 W / (mK) at 600°C. The second insulation layer 54 also adopts vertical insulation bricks with a thickness of 114 mm, but the insulation bricks of this layer take into account both compressive strength and thermal conductivity, with a compressive strength of 3.8 MPa and a thermal conductivity of 0.29 W / (mK) at 350°C. The third insulation layer 55 is a ceramic fiberboard bonded to the steel plate with a thickness of 50 mm and a density of 250 Kg / m 3 , the thermal conductivity at 600℃ is 0.09W / (mK).

[0033] Furnace base improvements: The steel plate is supported to the ground through a furnace base. The furnace base includes a supporting channel steel 56 and a phenolic plastic part 57. A plurality of the supporting channel steels 56 are spliced ​​together to form the skeleton of the furnace base. The phenolic plastic part 57 is configured in a block shape and is located between the supporting channel steels 56. The phenolic plastic part 57 is detachably fastened to the supporting channel steels 56. At least one of ceramic fiber materials, nano thermal insulation materials or nano thermal insulation coatings is filled in the furnace base skeleton.

[0034] The present invention uses phenolic plastic with excellent strength and heat insulation ability to make a connecting block installed in the middle of the channel steel, replacing part of the channel steel as the furnace bottom support, and the phenolic plastic and the channel steel are connected with bolts. This double support structure reduces the thermal bridge phenomenon of continuous transmission of heat energy from the furnace bottom through the channel steel without reducing the bearing strength.

[0035] In this embodiment, a 20-25 cm thick insulation layer is provided under the steel plate. This insulation layer mainly serves to reduce the heat dissipation from the furnace bottom. A 50 mm thick rock wool board 59 is laid at the bottom of the insulation layer. The density of the rock wool board is 120-180 kg / m 3 , which plays a supporting role. The rock wool board 59 is filled with a ceramic fiber blanket 58. The filling process adopts the method of plugging and tamping with a wooden stick at the same time. Ceramic fiber boards with a thickness of 25mm and a height of 0.4-0.6 meters are attached to both sides of the furnace base frame. The ceramic fiber boards are bonded to the outer surface of the furnace body with refractory cement or fixed with M6 welding nails. Bakelite boards with a thickness of 1-2mm are laid on the outside of the ceramic fiber boards, and the bakelite boards are painted with furnace body paint.

[0036] The above improvements are conducive to reducing the thermal bridge phenomenon at the bottom of the furnace and reducing the temperature rise on the surface of the furnace bottom. The surface temperature rise of the furnace bottom can be controlled within 50°C, which improves the insulation effect and plays an energy-saving role. Taking the roller-type mesh belt quenching furnace as an example, the power consumption per ton of quenching and tempering processing can be controlled at 0.38kw.h.kg -1 the following.

[0037] Embodiment 3

[0038] like Figure 1 , Figure 2 and Figure 3 As shown, the preheating unit 1 also includes a first heating frame 11 and a horizontal moving mechanism 15 arranged below the conveyor mesh belt 31, the first heating frame 11 is used to carry the first heating body 12, the horizontal moving mechanism 15 is used to drive the first heating frame 11 to move along the conveyor mesh belt 31, the heating control unit 4 is electrically connected to the horizontal moving mechanism 15, and is configured to control the movement of the horizontal moving mechanism 15 according to the signal feedback from the temperature sensor 8 to adjust the position of the first heating frame 11.

[0039] It should be noted that if the temperature sensor 8 detects that the surface temperature of the workpiece in the preheating unit 1 is relatively low, the heating control unit 4 drives the first heating frame 11 to move along the conveying direction of the conveyor mesh belt 31, thereby extending the heating time of the workpiece, achieving supplementary heating, avoiding the problem of uneven heating temperature, and improving heating uniformity.

[0040] In addition, the preheating unit 1 further includes a cooling fan 14 disposed at the bottom of the first heating rack 11 . The heating control unit 4 is electrically connected to the cooling fan 14 and is configured to adjust the rotation speed of the cooling fan 14 according to a signal fed back by the temperature sensor 8 .

[0041] It should be noted that if the temperature sensor 8 detects that the surface temperature of the workpiece is too high, the heating control unit 4 drives the cooling fan 14 to increase the speed to speed up the cooling speed. Otherwise, the cooling fan 14 is driven to reduce the speed or even shut down to slow down the cooling speed.

[0042] like Figure 1 , Figure 2 and Figure 4 As shown, the fine heating unit 2 also includes a second heating frame 21 and a lifting mechanism 24 arranged above the conveyor mesh belt 31. The second heating body 22 is fixedly arranged on the lower surface of the second heating frame 21. The lifting mechanism 24 is used to drive the second heating frame 21 to move closer to or away from the conveyor mesh belt 31. The heating control unit 4 is electrically connected to the lifting mechanism 24 and is configured to control the movement of the lifting mechanism 24 according to the signal feedback from the temperature sensor 8 to adjust the height of the second heating frame 21.

[0043] It should be noted that if the temperature sensor 8 detects that the surface temperature of the workpiece in the fine heating unit 2 is too high, the heating control unit 4 drives the second heating frame 21 away from the conveyor belt 31 to quickly reduce the heating temperature. Conversely, it drives the second heating frame 21 towards the conveyor belt 31 to quickly increase the heating temperature.

[0044] When in use, the quenching furnace in this embodiment can supplement the workpiece with heat or promptly remove the heat source based on the monitored real-time temperature of the workpiece. It has a fast response and precise adjustment, thus avoiding the problem of unstable quenching quality of the workpiece due to insufficient heating temperature or excessive heating temperature, and improving the quality and efficiency of quenching heating.

[0045] The improved technical solution of the energy-saving mesh belt quenching furnace provided in the above embodiment can be applied to continuous hot processing furnaces including annealing, normalizing, quenching, tempering, carburizing, carbonitriding and the like, as well as other industrial furnaces with similar furnace bottom overhead structure such as chain plate furnace, roller furnace, push rod furnace, etc., and has broad application prospects.

[0046] The above description is only an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An energy-saving mesh belt quenching furnace, characterized in that: It comprises a preheating unit (1), a fine heating unit (2), a workpiece conveying unit (3), a heating control unit (4) and a temperature sensor (8); The workpiece conveying unit (3) comprises a conveying mesh belt (31) for carrying and conveying the workpiece (6) to move forward in the furnace (51) and a rotating mechanism (32) for driving the conveying mesh belt (31); The preheating unit (1) is arranged in the furnace (51) and upstream of the conveyor mesh belt (31), and is used for performing initial heating on the workpiece (6). The preheating unit (1) comprises a first heating body (12) and a first heat exchange tube (13); The fine heating unit (2) is arranged in the furnace (51) and downstream of the conveyor mesh belt (31), and is used to perform secondary heating on the workpiece (6) after primary heating. The fine heating unit (2) comprises a second heating body (22) and a second heat exchange tube (23). The heating temperature of the second heating body (22) is higher than that of the first heating body (12). The second heat exchange tube (23) is connected to the first heat exchange tube (13) to form a circulation loop. A heat regulating pump (7) is arranged between the two heat exchange tubes. The temperature sensors (8) are multiple in number and are arranged at various locations in the furnace (51) to monitor the temperature of the workpiece (6) during initial heating, secondary heating, and when leaving the furnace (51); The heating control unit (4) is electrically connected to the workpiece conveying unit (3), the preheating unit (1), the fine heating unit (2), and the heat regulating pump (7) and is independently controlled. The heating control unit (4) is configured to maintain the temperature of the workpiece (6) within a set range when it leaves the furnace (51) by at least controlling the moving speed of the conveying mesh belt, the heating temperature of each heating body, and the opening of the heat regulating pump according to a signal fed back by the temperature sensor (8).

2. The energy-saving mesh belt quenching furnace according to claim 1, characterized in that: The fine heating unit (2) further comprises a second heating frame (21) and a lifting mechanism (24) arranged above the conveyor mesh belt (31); the second heating body (22) is fixedly arranged on the lower surface of the second heating frame (21); the lifting mechanism (24) is used to drive the second heating frame (21) to move closer to or farther from the conveyor mesh belt (31); the heating control unit (4) is electrically connected to the lifting mechanism (24) and is configured to control the movement of the lifting mechanism (24) according to a signal fed back by the temperature sensor (8) so as to adjust the height of the second heating frame (21).

3. The energy-saving mesh belt quenching furnace according to claim 1, characterized in that: The preheating unit (1) further comprises a first heating frame (11) and a horizontal moving mechanism (15) arranged below the conveyor mesh belt (31); the first heating frame (11) is used to carry a first heating body (12); the horizontal moving mechanism (15) is used to drive the first heating frame (11) to move along the conveyor mesh belt (31); the heating control unit (4) is electrically connected to the horizontal moving mechanism (15) and is configured to control the movement of the horizontal moving mechanism (15) according to a signal fed back by the temperature sensor (8) so as to adjust the position of the first heating frame (11).

4. The energy-saving mesh belt quenching furnace according to claim 3 is characterized in that: The preheating unit (1) further comprises a cooling fan (14) arranged at the bottom of the first heating rack (11); the heating control unit (4) is electrically connected to the cooling fan (14) and is configured to adjust the rotation speed of the cooling fan (14) according to a signal fed back by the temperature sensor (8).

5. The energy-saving mesh belt quenching furnace according to any one of claims 1 to 4, characterized in that: A composite insulation structure is arranged at the bottom of the furnace body, and a steel plate is arranged at the bottom of the composite insulation structure. The composite insulation structure includes a plurality of insulation layers which are arranged in sequence from the inside to the outside and whose compressive strength and thermal conductivity coefficient gradually decrease. The insulation layers are made of at least one of insulation bricks, ceramic fiber materials, nano insulation materials or nano insulation coatings.

6. The energy-saving mesh belt quenching furnace according to claim 5, characterized in that: The composite thermal insulation structure comprises a first thermal insulation layer (53), a second thermal insulation layer (54) and a third thermal insulation layer (55) which are arranged in sequence from the inside to the outside, the first thermal insulation layer (53) and the second thermal insulation layer (54) are both thermal insulation bricks, and the third thermal insulation layer (55) is a ceramic fiberboard.

7. The energy-saving mesh belt quenching furnace according to claim 5, characterized in that: It also includes a furnace base for supporting the entire furnace body, the furnace base including a supporting channel steel (56) and a phenolic plastic part (57), a plurality of the supporting channel steels (56) are spliced ​​together to form a furnace base frame, the phenolic plastic part (57) is arranged between the supporting channel steels (56) and is detachably fastened to adjacent supporting channel steels (56), and at least one of a ceramic fiber material, a nano thermal insulation material or a nano thermal insulation coating is filled in the furnace base frame.

8. The energy-saving mesh belt quenching furnace according to claim 7, characterized in that: A ceramic fiber blanket (58) is filled in the furnace base frame, a rock wool board (59) is laid on the bottom of the ceramic fiber blanket (58), and a ceramic fiber board is laid outside the furnace base frame.

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