Heat treatment device and method for cutter bearing of shield tunneling machine

Abstract

The invention relates to the technical field of bearing heat treatment, in particular to a shield tunneling machine cutter bearing heat treatment device and method.The heat treatment device comprises a vacuum carburizing furnace, induction heating quenching equipment, tempering equipment, subzero treatment equipment and a controller, the subzero treatment equipment comprises a rack, and a subzero treatment bin is installed above the rack; a feeding port and a discharging port are formed in the two ends of the cryogenic treatment bin in the length direction respectively, and a pre-cooling section, a cryogenic section and a annealing section are sequentially arranged between the feeding port and the discharging port. Temperature sensors are respectively mounted in the pre-cooling section, the deep cooling section and the annealing section, and are in communication connection with the controller; compared with the prior art, the subzero treatment equipment has the advantages that the shield tunneling machine cutter bearing in the subzero treatment equipment is subjected to subzero treatment through a gas method, and workpiece cracking caused by large thermal shock during subzero treatment through a liquid method is avoided; the liquid nitrogen atomization spraying amount is adjusted through a liquid flow adjusting valve on the second liquid pipeline, and the temperature in the pre-cooling section or the deep cooling section is controlled.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment of bearings, and in particular to a heat treatment device and method for a cutter bearing of a shield machine. Background Art

[0002] Shield machine cutter bearings mostly use tapered roller bearings, which can carry large radial loads and axial loads at the same time, and can ensure efficient and smooth output of cutter ring power. The inner and outer rings of tapered roller bearings are the main load-bearing components of the bearings. They are prone to early failure when serving in harsh environments and need to withstand frequent and large impact loads for a long time. Therefore, fatigue, fracture and wear are the main failure forms of most tapered roller bearings. It is necessary to improve the wear resistance and fatigue life of tapered roller bearing rings, so as to improve the bearing performance and extend the service life of shield machine cutter rings.

[0003] In the prior art, shield machine tool bearings are produced by carburizing, double quenching and tempering, but the wear resistance, fatigue life, strength and impact energy of shield machine tool bearings still have a lot of room for improvement. Cryogenic treatment can significantly improve the toughness of the workpiece without reducing the strength and hardness of the workpiece. In the prior art, cryogenic treatment mostly adopts liquid method. The liquid method is to put the workpiece directly into liquid nitrogen. The disadvantage is that the thermal shock is large, and sometimes even causes the workpiece to crack. Summary of the invention

[0004] In order to improve the wear resistance and fatigue life of tapered roller bearing rings and enhance the performance of the bearings, the present invention provides a shield machine tool bearing heat treatment device and method.

[0005] The present invention provides a shield machine tool bearing heat treatment device and method using the following technical solutions: A shield machine tool bearing heat treatment device includes a vacuum carburizing furnace, induction heating quenching equipment and tempering equipment; it also includes a cryogenic treatment device and a controller, the cryogenic treatment device includes a frame, a cryogenic treatment bin is installed above the frame, the two ends of the cryogenic treatment bin are respectively a feed port and a discharge port, and between the feed port and the discharge port are a pre-cooling section, a cryogenic section and an annealing section in sequence; temperature sensors are respectively installed in the pre-cooling section, the cryogenic section and the annealing section, and the temperature sensors are communicatively connected with the controller.

[0006] Preferably, the cryogenic treatment chamber comprises a lower chamber body and an upper chamber body, wherein the upper chamber body covers the lower chamber body and the length of the lower chamber body is greater than that of the upper chamber body.

[0007] Preferably, a circulating conveyor belt is horizontally installed in the lower bin body, and a plurality of ventilation holes are evenly arranged on the circulating conveyor belt; the upper surface of the circulating conveyor belt is flush with the upper surface of the lower bin body; the circulating conveyor belt includes a driving motor, and the driving motor is communicatively connected with the controller.

[0008] Preferably, there are multiple cryogenic sections; the upper bin body is respectively provided with a bin door at the intervals between the pre-cooling section and the cryogenic section, between the cryogenic section and the heat-release section, and between different cryogenic sections; partition plates are respectively fixedly arranged at the positions corresponding to the bin doors on the lower bin body, and through holes are arranged at the positions corresponding to the circulating conveyor belt on the partition plates.

[0009] Preferably, liquid nitrogen inlet pipes are respectively installed at the positions corresponding to the pre-cooling section and multiple cryogenic sections on the upper bin body, and nitrogen discharge pipes are respectively installed at the positions corresponding to the pre-cooling section and multiple cryogenic sections on the lower bin body; a liquid nitrogen atomizing nozzle is installed inside the liquid nitrogen inlet pipe, and a partition portion with a U-shaped longitudinal section is arranged inside the liquid nitrogen atomizing nozzle; the partition portion is fixedly connected with the inner surface of the upper bin body close to the liquid nitrogen atomizing nozzle side, and the liquid nitrogen atomizing nozzle atomizes and sprays liquid nitrogen into the partition portion and then the liquid nitrogen absorbs heat and vaporizes.

[0010] Preferably, the outside of the nitrogen discharge pipe is connected to the intake end of a liquid nitrogen generator through a gas pipe, the liquid outlet end of the liquid nitrogen generator is connected to a liquid nitrogen pump through a first liquid pipeline, and the outlet of the liquid nitrogen pump is connected to the outside of the liquid nitrogen inlet pipe through a second liquid pipeline; a gas flow regulating valve is installed on the gas pipe, and a liquid flow regulating valve is installed on the second liquid pipeline; the liquid nitrogen pump, the gas flow regulating valve and the liquid flow regulating valve are respectively communicatively connected with the controller.

[0011] A heat treatment method for a shield machine cutter bearing uses the shield machine cutter bearing heat treatment device to perform heat treatment on the shield machine cutter bearing, and the specific operation steps are as follows: Step S1, the shield machine cutter bearing is carburized at 900 - 950 °C and taken out of the furnace for oil cooling, and the material of the shield machine cutter bearing is bearing steel G20CrNi2Mo; Step S2, after the shield machine cutter bearing that has completed oil cooling is cleaned, high-temperature tempering is carried out, and the high-temperature tempering temperature is 500 - 550 °C; Step S3, then the surface layer of the shield machine cutter bearing that has been high-temperature tempered and cooled to room temperature is heated to 805 °C by an induction heating quenching device and then limited quenching is carried out; Step S4, the shield machine cutter bearing that has completed limited quenching is subjected to cryogenic treatment for 4h - 24h; Step S5, after the shield machine cutter bearing after cryogenic treatment reaches room temperature, low-temperature tempering treatment is carried out.

[0012] Preferably, in step S1, the carburizing treatment is completed in a vacuum carburizing furnace; the temperature in the vacuum carburizing furnace before oil cooling after furnace discharging is 900 °C.

[0013] Preferably, in step S4, the shield machine tool bearing after limited quenching is placed on a circulating conveyor belt at the feed inlet of the cryogenic treatment equipment, and then the shield machine tool bearing is successively pre-cooled in the pre-cooling section, cryogenically cooled in the cryogenic cooling section, and back-cooled in the back-cooling section, and finally discharged from the discharge outlet of the cryogenic treatment equipment; During the cryogenic treatment of the shield machine tool bearing in the cryogenic treatment equipment, the circulating conveyor belt operates in an intermittent movement mode, and all the hatch doors are opened before the circulating conveyor belt moves; after the circulating conveyor belt moves a set distance, it stops operating, and at this time all the hatch doors are closed.

[0014] Preferably, the cryogenic treatment equipment can realize continuous cryogenic treatment of multiple shield machine tool bearings, and the sum of the residence times of each shield machine tool bearing in multiple cryogenic cooling sections is equal to the set cryogenic holding time; the set temperature in the pre-cooling section is higher than the set temperature in the cryogenic cooling section.

[0015] In summary, the present invention has the following beneficial technical effects: (1) Adding cryogenic treatment between limited quenching and low-temperature tempering can not only improve the dimensional stability of the shield machine tool bearing, but also improve the wear resistance, hardness and strength of the shield machine tool bearing by promoting the transformation of retained austenite in the structure into martensite and promoting the precipitation of fine carbides; (2) The cryogenic treatment equipment uses the gas method to perform cryogenic treatment on the shield machine tool bearings therein, avoiding the workpiece cracking caused by large thermal shock during cryogenic treatment using the liquid method in the prior art; (3) The cryogenic treatment chamber includes an upper chamber body and a lower chamber body, which is convenient for maintenance and repair; (4) The circulating conveyor belt is evenly provided with a plurality of ventilation holes, which is convenient for cold air to enter the lower chamber body from the upper chamber body, and the temperature of the shield machine tool bearings on the circulating conveyor belt is uniform in the height direction; (5) The pre-cooling section, cryogenic cooling section and back-cooling section are arranged in sequence between the feed inlet and the discharge outlet of the cryogenic treatment chamber, which fully meets the requirements of the cryogenic treatment process; (6) A liquid nitrogen atomizing nozzle is installed inside the liquid nitrogen inlet pipe, and a partition part with a C-shaped longitudinal section is arranged inside the liquid nitrogen atomizing nozzle; the side of the partition part close to the liquid nitrogen atomizing nozzle is fixedly connected to the inner surface of the upper chamber body, and the liquid nitrogen atomizing nozzle atomizes and sprays liquid nitrogen into the partition part, and then the liquid nitrogen absorbs heat and vaporizes, and the temperature in the corresponding pre-cooling section or cryogenic cooling section drops; (7) By adjusting the liquid nitrogen atomizing spraying amount through the liquid flow regulating valve on the second liquid pipeline, the temperature control in the pre-cooling section or cryogenic cooling section is realized; (8) The cryogenic treatment equipment can realize continuous cryogenic treatment of multiple shield machine tool bearings, and the sum of the residence time of each shield machine tool bearing in multiple cryogenic sections is equal to the set cryogenic insulation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a three-dimensional cryogenic treatment device in the heat treatment device for the cutter bearing of the shield machine of the present invention. Figure 1 ; Figure 2 It is a three-dimensional cryogenic treatment device in the heat treatment device for the cutter bearing of the shield machine of the present invention. Figure 2 ; Figure 3 It is a front view of a cryogenic treatment device in a heat treatment device for a cutter bearing of a shield machine according to the present invention; Figure 4 It is a rear view of a cryogenic treatment device in a heat treatment device for a cutter bearing of a shield machine according to the present invention; Figure 5 This is a perspective view of the deep cold treatment equipment in the heat treatment device for the shield machine tool bearing of the present invention Figure 1 ; Figure 6 This is a perspective view of the deep cold treatment equipment in the heat treatment device for the shield machine tool bearing of the present invention Figure 2 ; Figure 7 It is a schematic diagram of a circulating conveyor belt in a cryogenic treatment equipment; Figure 8 It is a schematic diagram of the partition part in the cryogenic treatment equipment.

[0017] Description of reference numerals: 1—frame, 2—lower bin body, 3—upper bin body, 4—feed port, 5—bin door, 6—nitrogen gas discharge pipe, 7—liquid nitrogen inlet pipe, 8—circulating conveyor belt, 9—blocking part, 10—partition, 11—annealing section, 12—precooling section, 13—deep cooling section. DETAILED DESCRIPTION

[0018] The following is combined with Figure 1-Figure 8 The present invention is described in further detail.

[0019] The embodiment of the invention discloses a shield machine cutter bearing heat treatment device and method.

[0020] Embodiment 1 discloses a heat treatment device for a shield machine tool bearing.

[0021] Reference Figure 1-Figure 4, the heat treatment device for the cutter bearing of a shield machine includes a vacuum carburizing furnace, an induction heating quenching device, and a tempering device; it also includes a cryogenic treatment device and a controller. The cryogenic treatment device includes a frame 1, above which a cryogenic treatment chamber is installed. At both ends of the length of the cryogenic treatment chamber are an inlet 4 and an outlet respectively. Between the inlet 4 and the outlet are a pre-cooling section 12, a cryogenic section 13, and a heat recovery section 11 in sequence; temperature sensors are installed in the pre-cooling section 12, the cryogenic section 13, and the heat recovery section 11 respectively, and the temperature sensors are communicatively connected to the controller. Gas pressure sensors are also installed in the pre-cooling section 12 and the cryogenic section 13. At the inlet 4 and the outlet, a plurality of rubber sheets are vertically installed to play a role of flexible enclosure.

[0022] Refer to Figure 1-Figure 4 , the cryogenic treatment chamber includes a lower chamber body 2 and an upper chamber body 3. The upper chamber body 3 covers above the lower chamber body 2 and the length of the lower chamber body 2 is greater than that of the upper chamber body 3.

[0023] Refer to Figure 5-Figure 7 , a circulating conveyor belt 8 is horizontally installed in the lower chamber body 2. The circulating conveyor belt 8 is evenly provided with a plurality of ventilation holes; the upper surface of the circulating conveyor belt 8 is flush with the upper surface of the lower chamber body 2; the circulating conveyor belt 8 includes a driving motor, and the driving motor is communicatively connected to the controller.

[0024] As Figure 3 shown, the number of cryogenic sections 13 is multiple (to improve the temperature uniformity in a single cryogenic section 13); the upper chamber body 3 is respectively provided with chamber doors 5 at the intervals between the pre-cooling section 12 and the cryogenic sections 13, at the intervals between the cryogenic sections 13 and the heat recovery section 11, and at the intervals between different cryogenic sections 13; the lower chamber body 2 is respectively fixedly provided with partitions 10 at positions corresponding to the chamber doors 5, and through holes are opened at the positions of the partitions 10 corresponding to the circulating conveyor belt 8.

[0025] As Figure 2 shown, the chamber door 5 includes a bracket and a linear telescopic device vertically installed on the bracket. The lower end of the piston rod of the linear telescopic device is connected to the chamber door plate.

[0026] As Figure 2 , Figure 4 , Figure 6 and Figure 8 shown, the upper chamber body 3 is respectively provided with liquid nitrogen inlet pipes 7 at positions corresponding to the pre-cooling section 12 and the multiple cryogenic sections 13, and the lower chamber body 2 is respectively provided with nitrogen discharge pipes 6 at positions corresponding to the pre-cooling section 12 and the multiple cryogenic sections 13; a liquid nitrogen atomizing nozzle is installed inside the liquid nitrogen inlet pipe 7, and a partition portion 9 with a longitudinal cross-section in a U shape is provided inside the liquid nitrogen atomizing nozzle; the partition portion 9 is fixedly connected to the inner surface of the upper chamber body 3 near the liquid nitrogen atomizing nozzle, and the liquid nitrogen atomizing nozzle atomizes and sprays liquid nitrogen into the partition portion 9 and then the liquid nitrogen absorbs heat and vaporizes.

[0027] As Figure 5 and Figure 6As shown, the liquid nitrogen inlet pipe 7 and the nitrogen outlet pipe 6 are respectively located at both ends of the pre-cooling section 12 or the deep cooling section 13 in the length direction, promoting the flow of nitrogen in the length direction of the pre-cooling section 12 or the deep cooling section 13 and improving the temperature uniformity of the pre-cooling section 12 or the deep cooling section 13.

[0028] The outside of the nitrogen discharge pipe 6 is connected to the gas inlet end of the liquid nitrogen generator through an air pipe, the liquid outlet end of the liquid nitrogen generator is connected to the liquid nitrogen pump through liquid pipeline 1, and the outlet of the liquid nitrogen pump is connected to the outside of the liquid nitrogen pipe 7 through liquid pipeline 2; a gas flow regulating valve is installed on the air pipe, and a liquid flow regulating valve is installed on liquid pipeline 2; the liquid nitrogen pump, the gas flow regulating valve and the liquid flow regulating valve are respectively connected to the controller for communication.

[0029] The liquid nitrogen generator mainly includes the following parts: Compression system: compresses gaseous nitrogen into high-temperature and high-pressure liquid nitrogen; Condensation system: cools the high-temperature and high-pressure liquid nitrogen to lower its temperature; Liquefaction system: further compresses and cools the cooled liquid nitrogen.

[0030] The liquid nitrogen atomizing nozzle atomizes the liquid nitrogen, and the temperature of the baffle 9 is higher than the boiling point of the liquid nitrogen. At the same time, the liquid nitrogen pump causes the liquid nitrogen droplets to collide with the baffle 9 at high speed, which promotes the gasification of the liquid nitrogen.

[0031] Example 2 A shield machine tool bearing heat treatment method, using the shield machine tool bearing heat treatment device to heat treat the shield machine tool bearing, including the following specific operating steps: Step S1, the shield machine tool bearing is carburized at 900-950°C and oil-cooled after being taken out of the furnace. The shield machine tool bearing is made of bearing steel G20CrNi2Mo; Step S2, after the oil-cooled shield machine tool bearing is cleaned, high-temperature tempering is performed, and the high-temperature tempering temperature is 500-550° C.; Step S3, then using induction heating quenching equipment to heat the surface layer of the shield machine tool bearing that has been high-temperature tempered and cooled to room temperature to 805° C. and then perform limited quenching; Step S4, the shield machine tool bearing that has completed the limited quenching is subjected to a deep cryogenic treatment for 4h-24h; Step S5: After the shield machine tool bearing reaches room temperature after the cryogenic treatment, low-temperature tempering treatment is performed.

[0032] In step S1, carburizing is completed in a vacuum carburizing furnace; the temperature in the vacuum carburizing furnace is 900°C before oil cooling.

[0033] In step S4, the shield machine tool bearing that has completed limited quenching is placed on the circulating conveyor belt 8 at the feed port 4 of the cryogenic treatment equipment, and then the shield machine tool bearing is pre-cooled in the pre-cooling section 12, deep-cooled in the deep-cooling section 13, and annealed in the annealing section 11, and finally discharged from the discharge port of the cryogenic treatment equipment.

[0034] During the cryogenic treatment of the shield machine tool bearing in the cryogenic treatment equipment, the circulating conveyor belt 8 operates in an intermittent movement mode. Before the circulating conveyor belt 8 moves, all the bin doors 5 are opened; the circulating conveyor belt 8 stops running after moving a set distance, and all the bin doors 5 are closed.

[0035] The cryogenic treatment equipment can realize continuous cryogenic treatment of multiple shield machine tool bearings. The sum of the residence time of each shield machine tool bearing in multiple cryogenic sections 13 is equal to the set cryogenic insulation time; the set temperature in the precooling section 12 is higher than the set temperature in the cryogenic section 13. In this embodiment, the set temperature of the precooling section 12 is minus 70°C; the set temperature in the cryogenic section 13 is minus 130°C; there is no liquid nitrogen atomizing nozzle in the annealing section 11, but when the chamber door 5 is opened, the low-temperature nitrogen in the adjacent cryogenic section 13 will enter the annealing section 11, so the temperature in the annealing section 11 is between the room temperature and the temperature in the cryogenic section 13. The liquid nitrogen atomizing spraying amount is adjusted by the liquid flow regulating valve on the liquid pipeline 2 to realize the temperature control in the precooling section 12 or the cryogenic section 13 (the temperature of liquid nitrogen is extremely low, which is -196°C).

[0036] The low temperature tempering temperature in step S5 is 160°C.

[0037] The tensile strength of the shield machine tool bearing obtained by the above-mentioned heat treatment method is 1495MPa, the yield strength is 1210MPa, the elongation is 12.8%, the impact energy is 74.8J, and the hardness is 47.9HRC, which are respectively improved by about 2.3%, 1.9%, 2.4%, 11.2% and 4.1.% compared with the performance obtained by the traditional heat treatment process; the contact fatigue life is increased by about 76.0% compared with the sample with the traditional heat treatment process.

[0038] Example 3 The difference between this embodiment and embodiment 1 is that nitrogen purge pipes are also installed at the corresponding positions of the upper warehouse body 3 and the precooling section 12 and the multiple cryogenic sections 13. During nitrogen purge, air is discharged from the nitrogen discharge pipe 6. The air pipe is a three-way structure, and the air discharged through the nitrogen discharge pipe 6 is discharged to the atmosphere. Before the precooling section 12 and the multiple cryogenic sections 13 are cooled by the liquid nitrogen atomizing nozzle, pure nitrogen is introduced into the precooling section 12 and the multiple cryogenic sections 13 by the nitrogen purge pipe to avoid water droplets or ice (condensed by water vapor) in the precooling section 12 and the multiple cryogenic sections 13 during the cooling process.

[0039] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat treatment device for a shield machine tool bearing, comprising a vacuum carburizing furnace, an induction heating quenching device and a tempering device; characterized in that: It also includes a cryogenic treatment device and a controller. The cryogenic treatment device includes a frame (1). Above the frame (1), a cryogenic treatment chamber is installed. The two ends of the length of the cryogenic treatment chamber are respectively a feed inlet (4) and a discharge outlet. Between the feed inlet (4) and the discharge outlet are successively a pre-cooling section (12), a cryogenic section (13), and a tempering section (11). Temperature sensors are respectively installed in the pre-cooling section (12), the cryogenic section (13), and the tempering section (11), and the temperature sensors are communicatively connected to the controller.

2. The shield machine tool bearing heat treatment device according to claim 1, characterized in that: The cryogenic treatment chamber includes a lower chamber body (2) and an upper chamber body (3). The upper chamber body (3) covers above the lower chamber body (2), and the length of the lower chamber body (2) is greater than the length of the upper chamber body (3).

3. The shield machine tool bearing heat treatment device according to claim 2, characterized in that: A circulating conveyor belt (8) is horizontally installed in the lower chamber body (2). The circulating conveyor belt (8) is evenly provided with a plurality of ventilation holes. The upper surface of the circulating conveyor belt (8) is flush with the upper surface of the lower chamber body (2). The circulating conveyor belt (8) includes a driving motor, and the driving motor is communicatively connected to the controller.

4. The shield machine tool bearing heat treatment device according to claim 3, characterized in that: The number of the cryogenic sections (13) is multiple. The upper chamber body (3) is respectively provided with a chamber door (5) at the intervals between the pre-cooling section (12) and the cryogenic section (13), at the intervals between the cryogenic section (13) and the tempering section (11), and at the intervals between different cryogenic sections (13). Partition plates (10) are respectively fixedly provided at the positions corresponding to the chamber doors (5) on the lower chamber body (2), and through holes are provided at the positions corresponding to the circulating conveyor belt (8) on the partition plates (10).

5. The shield machine tool bearing heat treatment device according to claim 4, characterized in that: Liquid nitrogen inlet pipes (7) are respectively installed at the positions corresponding to the pre-cooling section (12) and multiple cryogenic sections (13) on the upper chamber body (3). Nitrogen discharge pipes (6) are respectively installed at the positions corresponding to the pre-cooling section (12) and multiple cryogenic sections (13) on the lower chamber body (2). Liquid nitrogen atomizing nozzles are installed inside the liquid nitrogen inlet pipes (7). Inside the liquid nitrogen atomizing nozzles, there is a partition portion (9) with a longitudinal section in the shape of a "匚". The side of the partition portion (9) close to the liquid nitrogen atomizing nozzle is fixedly connected to the inner surface of the upper chamber body (3). The liquid nitrogen atomizing nozzles atomize and spray liquid nitrogen into the partition portion (9), and then the liquid nitrogen absorbs heat and vaporizes.

6. The shield machine tool bearing heat treatment device according to claim 5, characterized in that: The outer side of the nitrogen discharge pipe (6) is connected to the intake end of a liquid nitrogen generator through a gas pipe. The liquid outlet end of the liquid nitrogen generator is connected to a liquid nitrogen pump through a first liquid pipe. The outlet of the liquid nitrogen pump is connected to the outer side of the liquid nitrogen inlet pipe (7) through a second liquid pipe. A gas flow regulating valve is installed on the gas pipe, and a liquid flow regulating valve is installed on the second liquid pipe. The liquid nitrogen pump, the gas flow regulating valve, and the liquid flow regulating valve are respectively communicatively connected to the controller.

7. A heat treatment method for a shield machine tool bearing, characterized in that: Using the shield machine tool bearing heat treatment device according to claim 6 to heat-treat the shield machine tool bearing, the specific operation steps are as follows: Step S1: The shield machine tool bearing is carburized at 900 - 950 °C and taken out of the furnace for oil cooling. The material of the shield machine tool bearing is bearing steel G20CrNi2Mo. Step S2: After the shield machine tool bearing that has completed oil cooling is cleaned, it is subjected to high-temperature tempering, and the high-temperature tempering temperature is 500 - 550 °C. Step S3, then using induction heating quenching equipment to heat the surface layer of the shield machine tool bearing that has been high-temperature tempered and cooled to room temperature to 805° C. and then perform limited quenching; Step S4, the shield machine tool bearing that has completed the limited quenching is subjected to a deep cryogenic treatment for 4h-24h; Step S5: After the shield machine tool bearing reaches room temperature after the cryogenic treatment, low-temperature tempering treatment is performed.

8. The shield machine tool bearing heat treatment method according to claim 7, characterized in that: In step S1, carburizing is completed in a vacuum carburizing furnace; the temperature in the vacuum carburizing furnace is 900°C before oil cooling.

9. The shield machine tool bearing heat treatment method according to claim 7, characterized in that: In step S4, the shield machine tool bearing that has completed the limited quenching is placed on a circulating conveyor belt (8) at the feed port (4) of the cryogenic treatment equipment, and then the shield machine tool bearing is pre-cooled in the pre-cooling section (12), deep-cooled in the deep-cooling section (13), and annealed in the annealing section (11), and finally discharged from the discharge port of the cryogenic treatment equipment; During the cryogenic treatment of the shield machine tool bearing in the cryogenic treatment equipment, the circulating conveyor belt (8) is operated in an intermittent movement mode, and all the bin doors (5) are opened before the circulating conveyor belt (8) moves; the circulating conveyor belt (8) stops running after moving a set distance, and all the bin doors (5) are closed at this time.

10. The shield machine tool bearing heat treatment method according to claim 9, characterized in that: The cryogenic treatment equipment can realize continuous cryogenic treatment of multiple shield machine tool bearings, and the sum of the residence time of each shield machine tool bearing in multiple cryogenic sections (13) is equal to the set cryogenic insulation time; the set temperature in the pre-cooling section (12) is higher than the set temperature in the cryogenic section (13).

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