A heavy-duty shield tunnel cutterhead ring, disc cutterhead and TBM shield equipment

Abstract

This invention discloses a heavy-duty shield tunneling cutterhead ring, a disc cutterhead, and a TBM (Tunnel Boring Machine) shield equipment, belonging to the technical field of tunneling equipment. The cutterhead ring's main metal element mass percentages are as follows: C: 0.48%–0.56%, Si: 0.68%–0.78%, Mn: 0.35%–0.47%, Cr: 5%–5.6%, Mo: 0.9%–1.5%, W: 0.45%–0.56%, V: 0.7%–0.85%, P / S: 0.013, Ni: 2.8%–3.6%, Cu: 0.085%–0.096%, with the remainder being Fe; its preparation process includes: ... The steel ingots obtained from the smelting of the metallic elements are subjected to high-temperature diffusion at 1250℃ and multi-directional forging. During the billet opening, they are repeatedly upset and drawn into round bars, forged into ultra-fine round bars, blanked, forged, rolled into rings, and then refined, spheroidized and annealed, roughed, and then subjected to composite heat treatment, vacuum quenching, and tempering heat treatment. The vacuum quenching is carried out at 1030℃ for 3-5 hours. The tempering heat treatment is carried out at 350℃ for 3 hours twice and at (530-540)℃ for 5 hours once. The overall hardness of the three tempering processes corresponds to HRC59, HRC60, and HRC62, respectively.

Description

Technical Field

[0001] This invention belongs to the field of tunneling equipment technology, and more specifically, relates to a heavy-duty shield cutterhead ring, disc cutterhead, and TBM (Tunnel Boring Machine) shield equipment. The shield cutterhead ring is suitable for 17-inch to 26-inch cutters, especially 24-26 inch cutters. Background Technology

[0002] Shield tunneling is widely used in tunnel construction due to its high efficiency, safety, and economic and environmental benefits, making it the best choice for modern tunnel engineering. The shield tunneling machine is its most modern and specialized equipment. The disc cutter head is a special cutting tool used on the shield tunneling machine for cutting rock and soil layers. Mounted on the cutterhead, the cutter rings of the disc cutter head penetrate the rock and soil layers during tunnel construction. Simultaneously, the cutterhead, driven by a rotating mechanism, causes the disc cutter head to rotate and revolve, continuously rolling and pressing the cutter head against the rock and soil layers, thus completing the continuous cutting and crushing of the rock and soil.

[0003] The commonly used TBM (Tunnel Boring Machine) cutterhead is a rock-breaking tool that crushes rock by rolling and compressing it with the cutter ring. The quality of the TBM cutterhead directly determines the rock-breaking efficiency of the tunnel boring machine. The TBM cutterhead consists of two sets of tapered roller bearings mounted back-to-back on a roller shaft, separated by a spacer ring. The cutter ring is mounted on the outer circumference of the roller. During operation, the roller shaft remains stationary, while the cutter ring rotates around the roller shaft along with the roller and the outer ring of the bearing. Simultaneously, the cutterhead revolves around the center of the cutterhead to achieve the purpose of crushing rock. This shows that the performance of the cutter ring, as a crucial component of the hob, largely determines the hob's service life. The article "Research on Heat Treatment Process of TBM Disc Hob Cutter Ring Materials" reveals that: Wirth and Robbins are the most typical brands of TBM disc hobs. Wirth hob cutter rings primarily use hot work die steels such as the German DIN standard grade X50CrVMo5-1, while Robbins hob cutter rings primarily use alloy structural steels such as the American AISI standard grade 4340. Japanese hob cutter rings primarily use cold work die steels such as the Japanese (JS) G4404 standard grade SKD11. Furthermore, currently, domestically produced cutter ring materials mostly use national standard grades such as 9Cr2Mo (GB / T 1299-2014), 40CrNiMo (GB / T 3077-2015), and 4Cr5MoSiV1 (GB / T1299-2014).

[0004] Furthermore, research on the composition of cutterhead materials has been ongoing in China. For example, a search reveals that Chinese patent CN106756592A discloses a roller cutterhead for tunnel shield construction, comprising a disc-shaped cutterhead body. The cutterhead body includes a stepped assembly portion for welding and assembly with a cutter hub and a working cutting edge portion for cutting. The outer edge of the cutterhead body has a nitrided layer formed by plasma nitriding. The cutterhead body is made of cemented carbide steel, and the elemental composition of the cemented carbide steel contains 0.46-0.55wt% C, 0.20-0.80wt% Mn, 1.5-3.5wt% Cr, and 0.30-0.80wt% W. The composition comprises t% Mo, 0.32-0.80wt% Cu, 0.05-0.20wt% V, with the balance being Fe and unavoidable metallic and non-metallic impurities; the unavoidable non-metallic impurities include Si, N, S, P and O, and the content of Si is ≤0.20wt%, the content of N is ≤0.010wt%, the content of P is ≤0.010wt%, the content of S is ≤0.010wt%, and the content of O is ≤20ppm; the unavoidable metallic impurities include Ti, Zr and Al, and the content of Ti is ≤0.02wt%, the content of Zr is ≤0.02wt%, and the content of Al is ≤0.05wt%.

[0005] For example, Chinese patent CN103484783A discloses an alloy for a disc-shaped hob cutter ring. The alloy composition by mass percentage is: C 0.4%–0.46%, Si 0.45%–1.0%, Mn 0.48%–0.74%, Cr 1.3%–5.4%, Mo 0.4%–1.4%, V 0.86%–1.33%, Nb 0.06%–0.54%, Al 0%–0.05%, Ni 0%–3%, S≤0.009%, P≤0.03%, with the balance being Fe. The preparation method includes vacuum induction melting of the raw materials, casting, forging, spheroidizing annealing, gas carburizing, vacuum quenching, and secondary tempering. The resulting disc-shaped hob cutter ring has a carburized layer thickness of up to 1 mm, a surface hardness of 60–63 HRC, an internal average hardness greater than 55 HRC, and an impact toughness (AkJ) of 15–22 J / cm². 2 The shield cutterhead ring is not only hard but also tough.

[0006] For example, Chinese patent CN107345267A discloses the following composition and mass percentage of a disc cutter for TBM: carbon 0.46%–0.58%; silicon 0.80%–1.20%; manganese 0.20%–0.60%; chromium 4.50%–5.80%; nickel 0.15%–0.40%; molybdenum 1.15%–1.55%; vanadium 0.85%–1.40%; phosphorus less than 0.02%; sulfur less than 0.01%; and the balance being iron.

[0007] For example, Chinese patent CN105443137A discloses an integral cutter ring for a disc hob. The chemical composition of this integral cutter ring, by mass percentage, is as follows: C: 0.39-0.42, Si: 0.25-0.28, Mn: 0.63-0.69, Cr: 0.74-0.78, Mo: 0.16-0.19, Ni: 1.38-1.44, W: 0.12-0.16, Nb: 0.15-0.18, Cu: 0.04-0.09, S: 0.005-0.009, P: 0.01-0.015, with the balance being Fe.

[0008] Based on the aforementioned material composition, the production process of the blade ring involves forging, annealing, quenching, and tempering. Among these, quenching and tempering, as the final heat treatment methods, have a decisive impact on the final performance of the blade ring. Therefore, many domestic researchers have conducted extensive research on heat treatment methods: Yan Hong, Chen Lei, and others invented a device for quenching blade rings, which ensures that the cooling rate of the inner circle and core of the blade ring is lower than that of the cutting edge during quenching, thus giving the inner circle and core a microstructure different from the cutting edge; Yang Longxing ensured the quenching quality of the blade ring by controlling the furnace entry temperature, heating rate, quenching temperature, and holding time; Chen Lei determined the optimal quenching and tempering process parameters for the blade ring by setting different quenching and tempering temperatures and holding times through comprehensive analysis.

[0009] However, extensive use has revealed that the overall hardness and impact toughness of the existing blade rings need further improvement. Summary of the Invention

[0010] 1. The problem to be solved

[0011] To address the technical problems existing in the prior art, the present invention provides a heavy-duty shield tunnel cutterhead ring that improves the overall hardness and impact toughness of the cutterhead ring.

[0012] Another objective of this invention is to provide a heavy-duty shield tunneling disc cutterhead.

[0013] Another object of the present invention is to provide a TBM shield tunneling device having the disc cutter head.

[0014] 2. Technical Solution

[0015] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0016] The first aspect of this invention provides a heavy-duty shield tunneling cutterhead ring, the main metal elements of which are present in the following mass percentages: C: 0.48%–0.56%, Si: 0.68%–0.78%, Mn: 0.35%–0.47%, Cr: 5%–5.6%, Mo: 0.9%–1.5%, W: 0.45%–0.56%, V: 0.7%–0.85%, P / S: 0.013, Ni: 2.8%–3.6%, Cu: 0.085%–0.096%, with the remainder being Fe; the heat treatment process includes: high-temperature diffusion and multi-directional forging of steel ingots obtained by smelting the aforementioned metal elements at 1250℃, repeated upsetting and drawing into round steel during billet preparation, forging and refining into a round shape + blanking and rolling into a ring + secondary refinement + spheroidizing annealing + rough machining followed by composite heat treatment + vacuum quenching and tempering heat treatment; the cutterhead ring is vacuum quenched at 1030℃. (3-5 hours); 3 tempering heat treatments: 350℃ 3h 2 times; (530-540)℃ 5h The overall hardness after one tempering and three temperings is not less than HRC59, not less than HRC60, and not less than HRC62, respectively.

[0017] Tests showed that 10 10 Standard U-shaped pendulum impact test results: 1) Overall hardness HRC (Rockwell hardness) 58-59, impact energy aku2=28J, impact toughness ak: 35J / cm 2 2) Overall hardness HRC60-62, aku2=14.75J, impact toughness: 17.8125J / cm 2 .

[0018] According to any embodiment of the first aspect of the present invention, the ultrafine refining of the forged round includes: heating to 1050°C in a stepped manner and holding for 3 hours, followed by water quenching and air cooling, repeating this alternating process. The water quenching time and air cooling time are adjusted according to the diameter and length of the forged round, cycling until the air cooling temperature after the last water quenching is between 150°C and 200°C. The round is then immediately transferred to a trolley furnace set at 920°C for heating and holding to ensure uniform heating for 5-7 hours. It is then cooled in the furnace to approximately 765°C-720°C, held for 6-7 hours, and then cooled in the furnace to 350°C before being removed from the furnace. The secondary refining steps are the same as above. The sample obtained after the above steps has a grain size of 8.5 or higher.

[0019] According to any embodiment of the first aspect of the present invention, the multi-directional forging includes: a multi-directional forging temperature, an initial forging temperature of 1130-1150°C, a final forging temperature of 900±10°C, and a reduction rate gradually decreasing from 40%-30%-20%-10%-5% to stabilize the heat source.

[0020] According to any embodiment of the first aspect of the present invention, the composite heat treatment is a carbonitriding composite heat treatment process, with a diffusion layer depth of 1.1-1.3 mm and a diffusion layer strength of 850℃-870℃, which can improve the wear resistance and contact fatigue resistance of the blade ring.

[0021] A second aspect of the present invention provides a heavy-duty shield tunneling disc cutterhead, comprising:

[0022] A cutter shaft having a journal step and a thread along the outer circumference of the cutter shaft;

[0023] An upper tapered roller bearing and a lower tapered roller bearing are fitted onto the cutter shaft. The inner sleeves of the two tapered roller bearings are heat-fitted onto the cutter shaft at 80°C. The upper tapered roller bearing and the lower tapered roller bearing are separated by a spacer. An elastic spacer is installed between the end faces of the inner sleeves of the upper tapered roller bearing and the lower tapered roller bearing. When the two tapered roller bearings are pre-tightened, the elastic properties of the spacer are used to adjust the bearing clearance to achieve the required pre-tightening force.

[0024] A cutter hub is fitted around the upper tapered roller bearing and the lower tapered roller bearing. When the cutter ring is hot-mounted onto the cutter hub, the outer rings of the upper tapered roller bearing and the lower tapered roller bearing are quickly and smoothly placed into the corresponding bearing outer ring positions of the cutter hub after the cutter hub has a suitable thermal expansion time.

[0025] At least one cutting ring (in some cases, more than two cutting rings may be provided) is sleeved on the outer circumference of the cutting hub, and a retaining ring is provided on one side of the cutting ring, and the retaining ring is fixed to the cutting hub (e.g., by welding).

[0026] The upper cover assembly and the lower cover assembly are disposed at both axial ends of the cutter shaft. An upper floating seal is provided between the upper cover assembly and the upper tapered roller bearing; a lower floating seal is provided between the lower cover assembly and the lower tapered roller bearing.

[0027] According to any embodiment of the second aspect of the present invention, the elastic spacer is made of high-quality spring steel and has an H-shaped profile. The elastic spacer undergoes initial blank machining, heat treatment and tempering, and fine machining to form the shape. Surprisingly, both the upper and lower tapered roller bearings abut against the H-shaped elastic spacer. The H-shaped structure effectively ensures the end face strength of the elastic spacer and possesses good elastic deformation mechanical properties. Through extensive testing and usage analysis, it has been found that, while ensuring the upper and lower tapered roller bearings are on the upper and lower end caps, the H-shaped elastic spacer can adjust the preload, thereby adjusting the clearance of the upper and lower tapered roller bearings. This allows for the configuration of reasonable hob starting torque and rotation torque according to different geological requirements.

[0028] According to any embodiment of the second aspect of the present invention, the upper cover assembly includes an upper end cover, an upper oil seal bracket, a locking plate, an upper sealing dust ring, a pressure relief valve, and a plurality of O-rings A;

[0029] The upper end cover is pre-tightened to the large end face of the upper tapered roller bearing by the internal thread and the cutter shaft. During the pre-tightening process of the upper tapered roller bearing, an O-ring A is installed between the upper end cover and the large end face of the inner sleeve of the upper tapered roller bearing to seal the end face.

[0030] The upper end cover is pre-tightened with the cutter shaft at the large end face of the upper tapered roller bearing using an internal thread. At the same time, the upper tapered roller bearing, the lower tapered roller bearing, and the intermediate elastic spacer are pre-tightened synchronously to adjust the surrounding rock strength corresponding to the cutter torque.

[0031] The upper oil seal bracket is disposed inside the upper end cover, and the upper floating seal is disposed on the upper oil seal bracket; the end face between the upper oil seal bracket and the blade hub is sealed with at least two O-rings A.

[0032] The upper oil seal bracket is made of 42CrMo quenched and tempered material, precision machined, and then subjected to a 0.7mm nitriding process on the surface. Alternatively, the quenched and tempered part is rough machined and then induction hardened on the outer bevel to improve the surface wear resistance. Finally, the internal dimensions are precision machined to complete the design dimensions.

[0033] During assembly, the upper end cover and the upper oil seal bracket are sealed by the upper sealing dust ring through a static friction gap stepped seal, which enhances the sealing effect and maximizes the resistance to mud and sand erosion without affecting the starting torque; an O-ring A is also added between the two and sealed below the upper sealing dust ring.

[0034] The L-shaped upper sealing dustproof ring is made of high-molecular ultra-wear-resistant polyimide TPI material, which has the advantages of dimensional stability, high rigidity, good toughness, wear resistance, high temperature resistance, and corrosion resistance. It better stabilizes the sealing performance of the cutter hub, strictly prevents the erosion of the cutter hub by mud and sand particles, further protects the upper floating seal and upper tapered roller bearing inside the cutter hub for safe use, and has practical significance in extending the service life of heavy-duty hobs.

[0035] After the upper end cover is pre-tightened in place, the locking piece is fitted onto the upper end of the cutter shaft and the surrounding bevel is welded. It is positioned on the cutter shaft and the upper end cover to stop the welding and prevent the upper end cover thread from loosening and affecting the overall pre-tightening force of the upper tapered roller bearing.

[0036] The upper end cover has two symmetrically distributed ZG1 / 4 holes for oil injection and gas testing, and is equipped with a single-hole pressure relief valve. When the internal pressure of the tool hub is greater than the external pressure by 3 bar, the internal pressure is automatically discharged to balance the internal pressure of the tool hub and protect the safe use of the floating seal inside the tool hub.

[0037] According to any embodiment of the second aspect of the present invention, the lower cover assembly includes a bearing support, a lower end cover, a lower oil seal bracket, a lower sealing dust ring, and a plurality of O-rings B;

[0038] The bearing support is heat-fitted to the bottom of the cutter shaft and abuts against the journal step. The bearing support and the journal step are sealed with O-rings B. The bearing support and the inner ring of the lower tapered roller bearing are sealed with O-rings B. The outer circumferential surface of the bearing support is threaded. The lower end cover is pre-tightened with the threaded connection and an O-ring B is provided at the end face contact part.

[0039] The lower oil seal bracket is disposed inside the lower end cover, and the lower floating seal is disposed on the lower oil seal bracket; the end face between the lower oil seal bracket and the blade hub is sealed with at least two O-rings B;

[0040] The lower oil seal bracket is made of 42CrMo quenched and tempered material, precision machined, and then subjected to a 0.7mm nitriding process on the surface. Alternatively, the quenched and tempered part is rough machined and then induction hardened on the outer bevel to improve the surface wear resistance. Finally, the internal dimensions are precision machined to complete the design dimensions.

[0041] During assembly, the lower end cover and the lower oil seal bracket are sealed by a static friction gap stepped seal through the lower sealing dust ring, which enhances the sealing effect and maximizes the resistance to mud and sand erosion without affecting the starting torque; an O-ring B is also added between the two and sealed above the lower sealing dust ring.

[0042] The L-shaped lower sealing dust ring is made of high-molecular ultra-wear-resistant polyimide (TPI) material, which has the advantages of dimensional stability, high rigidity, good toughness, wear resistance, high temperature resistance, and corrosion resistance. It better stabilizes the sealing performance of the cutter hub, strictly prevents mud and sand particles from intruding into the cutter hub, and further protects the lower floating seal and lower tapered roller bearing inside the cutter hub for safe use. It is of practical significance to extend the service life of heavy-duty hobs.

[0043] A third aspect of the present invention provides a TBM (tunnel boring machine) with the disc cutterhead described in the second aspect, comprising a cutterhead on which the disc cutterhead is disposed.

[0044] 3. Beneficial effects

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] (1) The heavy-duty shield tunneling cutterhead ring of the present invention has an overall hardness of HRC58-59, aku2=28J, and an impact toughness of 35J / cm. 2 When the overall hardness is HRC 60-62, aku² = 14.75 J, the impact toughness is 17.8125 J / cm². 2 The metallographic structure is martensitic, which significantly improves the mechanical properties compared to the existing 5H13 material, resulting in better performance of the cutting tool ring and effectively extending its service life.

[0047] (2) The heavy shield tunneling disc cutter of the present invention has an L-shaped lower sealing dustproof ring made of high-molecular ultra-wear-resistant polyimide TPI material, which has the advantages of dimensional stability, high rigidity, good toughness, wear resistance, high temperature resistance and corrosion resistance. It can better stabilize the sealing performance of the cutter hub, prevent mud and sand particles from intruding into the cutter hub, further protect the lower floating seal and lower tapered roller bearing inside the cutter hub for safe use, and extend the service life of the heavy cutter. Attached Figure Description

[0048] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0049] Figure 1 The grain size test results are for the heavy-duty shield tunneling disc cutterhead ring of the present invention;

[0050] Figure 2 This is a schematic diagram of the heavy-duty shield tunneling disc cutter of the present invention;

[0051] Figure 3 for Figure 2 An enlarged structural diagram of part A;

[0052] Figure 4 for Figure 2 An enlarged structural diagram of part B;

[0053] Figure 5 This is a schematic diagram of the spacer ring installation structure of the heavy shield tunnel disc cutter of the present invention;

[0054] Figures 6-8 A third-party inspection report for the existing 5H13 heavy-duty shield tunnel disc cutterhead ring;

[0055] Figures 9-11 This is a third-party testing report for the heavy-duty shield tunneling disc cutterhead of Example 1;

[0056] Figure 12 The value represents the impact toughness of the heavy shield tunnel disc cutterhead ring in Example 1.

[0057] Explanation of reference numerals in the attached figures:

[0058] 1. Cutter shaft; 1-1. Journal step; 2. Upper tapered roller bearing; 3. Lower tapered roller bearing; 4. Spacer ring; 5. Cutter hub; 6. Cutter ring; 7. Retaining ring;

[0059] 8. Top cover assembly; 8-1. Top end cover; 8-2. Upper oil seal bracket; 8-3. Locking plate; 8-4. Upper sealing dust ring; 8-5. Pressure relief valve; 8-6. O-ring A;

[0060] 9. Lower cover assembly; 9-1. Bearing support seat; 9-2. Lower end cover; 9-3. Lower oil seal bracket; 9-4. Lower sealing dust ring; 9-5. O-ring B; 9-6. Configuration hole;

[0061] 10. Floating seal;

[0062] 11. Lower floating seal. Detailed Implementation

[0063] The following detailed description of exemplary embodiments of the invention is taken with reference to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which the invention may be practiced. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from the spirit and scope thereof. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and not restrictive of the description of the features and characteristics of the invention, to suggest the best mode for carrying out the invention, and is sufficient to enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0064] The following detailed description and exemplary embodiments of the invention can be better understood in conjunction with the accompanying drawings, wherein the elements and features of the invention are identified by reference numerals.

[0065] When TBM tunneling equipment operates in strata with relatively uniform rock structure, the load change on the cutterhead is relatively gradual. However, when the TBM operates in rock strata with uneven hardness or when the rock structure suddenly hardens, it may cause localized instantaneous overload of the cutterhead ring 6, leading to its breakage. Therefore, it is necessary to improve the overall strength of the cutterhead ring 6. The main metal element mass percentages of the heavy-duty shield cutterhead ring 6 of this invention are as follows: C: 0.48%~0.56%, Si: 0.68%~0.78%, Mn: 0.35%~0.47%, Cr: 5%~5.6%, Mo: 0.9%~1.5%, W: 0.45%~0.56%, V: 0.7%~0.85%, P / S: 0.013, Ni: 2.8%~3.6%, Cu: 0.085%~0.096%, the remainder being Fe; its heat treatment process includes: high-temperature diffusion and multi-directional forging of steel ingots obtained by smelting the aforementioned metal elements at 1250℃, repeated upsetting and drawing into round steel during billet preparation, forging round ultra-fine refinement + blanking forging and rolling into a ring billet + secondary refinement + spheroidizing annealing + rough machining followed by composite heat treatment + vacuum quenching and tempering heat treatment; to prevent surface decarburization of the blade ring 6 during quenching heating, the blade ring 6 is vacuum quenched at 1030℃. (3-5h); The quenched blade ring 6 should be heat-treated promptly, with three tempering heat treatments at 350℃. 3h 2 times; (530-540)℃ 5h The overall hardness after one tempering and three temperings is not less than HRC59, not less than HRC60, and not less than HRC62, respectively.

[0066] The process involves controlling the P / S ratio to minimize the percentage content of harmful elements such as S and P. The purpose of the three tempering processes is that the blade ring 6 of this invention has a high alloy element content, resulting in a high residual austenite content and low hardness in the whole-phase microstructure after quenching. The first tempering after quenching promotes the decomposition of some austenite and tempers the quenched martensite. During the cooling process of the first tempering, some undecomposed austenite transforms into secondary martensite. The second tempering tempers the secondary martensite and further promotes austenite decomposition, reducing the austenite content. The third tempering achieves a lower austenite content, improving the material's hardness and microstructure stability, resulting in a martensitic microstructure with uniform hardness distribution.

[0067] The blade ring 6 obtained by this invention was tested and found to be 10 10 Impact test of a standard U-shaped pendulum with a diameter of 55 mm: 1) Overall hardness HRC58-59, aku2=28J, impact toughness: 35J / cm 2 2) Overall hardness HRC60-62, aku2=14.75J, impact toughness: 17.8125J / cm 2 .

[0068] It should be noted that 6Cr4Mo2W2V, which has a composition similar to that of this invention, is a high-alloy mold steel containing 1.8%–2.2% W, 0.8%–1.2% V, and 2.2%–2.6% Mo. It also contains high levels of chromium, molybdenum, and tungsten, exhibiting good hardenability, wear resistance, and toughness, making it suitable for applications requiring high rock compressive hardness. However, the composition of this invention contains 0.45%–0.56% W, 0.7%–0.85% V, 0.9%–1.5% Mo, and 0.085%–0.096% Cu. The significant difference in composition between this invention and 6Cr4Mo2W2V is likely due to the addition of Cu, which reduces the content of chromium, molybdenum, and tungsten without compromising overall Rockwell hardness and impact toughness.

[0069] In this invention, the ultra-fine refining of the forged round includes: heating and holding at 1050°C in stages for 3 hours, followed by water quenching and air cooling, repeating the alternating operation. The water quenching time and air cooling time are adjusted according to the diameter and length of the forged round. The cycle continues until the air cooling temperature is 150°C-200°C after the last water quenching. Then, the round is immediately transferred to a trolley furnace set at 920°C for heating and holding to ensure uniform heating. After holding at this temperature for 5-7 hours, the round is cooled to approximately 765°C-720°C in the furnace and held for 6-7 hours. Finally, the round is cooled to 350°C in the furnace and removed from the furnace. The secondary refining steps are the same as above.

[0070] Furthermore, the multi-directional forging includes: a multi-directional forging temperature of 1130-1150℃ for the initial forging temperature and 900±10℃ for the final forging temperature, with the reduction rate gradually decreasing from 40%-30%-20%-10%-5% to stabilize the heat source.

[0071] Furthermore, the composite heat treatment is a carbonitriding composite heat treatment process, with a diffusion layer depth of 1.1-1.3mm and a diffusion layer strength. Carbonitriding is carried out at a temperature of 850℃-870℃, which can improve the wear resistance and contact fatigue resistance of the blade ring 6.

[0072] The specific spheroidizing annealing process includes: heating the blade ring 6 to 880-900℃ and then cooling it in the furnace to 750-760℃, holding it at that temperature for 1 hour, then heating it again to 880-900℃ and then cooling it in the furnace to 750-760℃ and holding it at that temperature.

[0073] Combination Figures 2 to 5As shown, the heavy-duty shield tunneling disc cutter of the present invention includes a cutter shaft 1, an upper tapered roller bearing 2, a lower tapered roller bearing 3, a cutter hub 5, a cutter ring 6, an upper cover assembly 8, and a lower cover assembly 9.

[0074] Among them, Figure 2 In this design, the cutter shaft 1 has a journal step 1-1 and a thread along its outer circumference. An upper tapered roller bearing 2 and a lower tapered roller bearing 3 are fitted onto the cutter shaft 1. The inner sleeves of the two tapered roller bearings are heat-fitted onto the cutter shaft 1 at 80°C. The upper tapered roller bearing 2 and the lower tapered roller bearing 3 are separated by a spacer 4. An elastic spacer 4 is installed between the end faces of the inner sleeves of the upper tapered roller bearing 2 and the lower tapered roller bearing 3. During the pre-tightening of the two tapered roller bearings, the elastic properties of the spacer 4 are used to adjust the clearance of the tapered roller bearings to achieve the required pre-tightening force.

[0075] The starting torque of a hob is primarily achieved by adjusting the clearance between the outer and inner ring cage rollers of two sets of tapered roller bearings. Since the position of the bearing outer ring is fixed, the clearance is mainly adjusted by changing the height of the spacer between the inner rings of the two bearing cage rollers. However, the hob hub, cutter shaft, end cap, bearings, floating seals, and other components related to torque are all machined products, and the dimensional tolerances of each component cannot be perfectly consistent. The dimensional accuracy after assembly is cumulative. Therefore, adjusting the bearing clearance often requires individual configuration for each hob, specifically configuring the bearing spacer. Currently, the method for adjusting the spacer height involves selecting a spacer of a certain height, fitting it onto the cutter shaft for a complete pre-assembly, measuring the actual torque, and then adjusting the thickness or thinning of the spacer in 0.5mm steps based on the measured torque. Repeated trial assembly of the hob is necessary to achieve or approximate the process-set torque.

[0076] It should be noted that in this embodiment, the elastic spacer 4 is made of high-quality spring steel (e.g., 60Si2Mn). Figure 5 As shown, its outline is H-shaped. Surprisingly, both the upper and lower tapered roller bearings rest on the H-shaped elastic spacer. The H-shaped structure effectively ensures the end face strength of the elastic spacer, and also possesses good elastic deformation mechanical properties. Through extensive testing and usage analysis, it has been found that, while ensuring the upper and lower tapered roller bearings are properly seated on the upper and lower end covers, the H-shaped elastic spacer can adjust the preload, thereby regulating the clearance of the upper and lower tapered roller bearings. This allows for the configuration of appropriate hob starting and rotating torques according to different geological requirements.

[0077] Furthermore, the manufacturing process of the elastic spacer ring 4 is as follows: steel pipe blanking -- rough turning -- heat treatment and tempering: quenching temperature 870℃, holding for 2 hours followed by oil quenching, tempering temperature 480℃, tempering time 3 hours, and water cooling after removal from the furnace. The mechanical properties are as follows:

[0078]

[0079] exist Figure 2 In this process, the cutter hub 5 is sleeved on the outside of the upper tapered roller bearing 2 and the lower tapered roller bearing 3; when the cutter ring 6 is hot-mounted onto the cutter hub 5, the outer rings of the upper tapered roller bearing 2 and the lower tapered roller bearing 3 are quickly and smoothly placed into the corresponding bearing outer ring positions of the cutter hub 5 after the cutter hub 5 has a suitable thermal expansion time.

[0080] like Figure 2 and Figure 3 As shown, a blade ring 6 is fitted around the outer circumference of the blade hub 5. A retaining ring 7 is provided on one side of the blade ring 6, and the retaining ring 7 is fixed to the blade hub 5. The blade angle of the blade ring 6 is 16°. The blade ring 6 adopts an interference fit and is generally heated to 100-200°C before being installed on the blade body. The retaining ring 7 can be two semi-circular rings, which are inserted into the groove of the blade hub 5 and then welded into a complete ring.

[0081] like Figure 2 , Figure 3 and Figure 4 As shown, the upper cover assembly 8 and the lower cover assembly 9 are disposed at both axial ends of the cutter shaft 1. An upper floating seal 10 is provided between the upper cover assembly 8 and the upper tapered roller bearing 2; a lower floating seal 11 is provided between the lower cover assembly 9 and the lower tapered roller bearing 3. The structures of the upper floating seal 10 and the lower floating seal 11 are both disclosed in the prior art.

[0082] Combination Figure 2 and Figure 3 The upper cover assembly 8 includes an upper end cover 8-1, an upper oil seal bracket 8-2, a locking piece 8-3, an upper sealing dust ring 8-4, a pressure relief valve 8-5, and several O-rings A8-6. The upper end cover 8-1 is pre-tightened with the cutter shaft 1 at the large end face of the upper tapered roller bearing 2 using an internal thread. During the pre-tightening process of the upper tapered roller bearing 2, an O-ring A8-6 is installed between the upper end cover 8-1 and the large end face of the inner sleeve of the upper tapered roller bearing 2 for end face sealing. The upper end cover 8-1 is pre-tightened with the cutter shaft 1 at the large end face of the upper tapered roller bearing 2 using an internal thread, and the upper tapered roller bearing 2, the lower tapered roller bearing 3, and the intermediate elastic spacer 4 are simultaneously pre-tightened to adjust the surrounding rock strength corresponding to the hobbing torque.

[0083] In this embodiment, as Figure 3As shown, the upper oil seal bracket 8-2 is disposed inside the upper end cover 8-1, and the upper floating seal 10 is disposed on the upper oil seal bracket 8-2; the end face between the upper oil seal bracket 8-2 and the blade hub 5 is sealed with two O-rings A8-6; the upper oil seal bracket 8-2 is made of 42CrMo tempered material, precision machined, and then subjected to a 0.7mm nitriding process on the surface, or the tempered part is rough machined and then induction hardened on the outer bevel to improve the surface wear resistance, and then the internal dimensions are precision machined to complete the design dimensions.

[0084] During assembly, the upper end cover 8-1 and the upper oil seal bracket 8-2 are sealed by the upper sealing dust ring 8-4 through a static friction gap stepped seal, which enhances the sealing effect and maximizes the resistance to mud and sand erosion without affecting the starting torque; an O-ring A8-6 is also added between the two and sealed below the upper sealing dust ring 8-4.

[0085] Furthermore, the cutter head of this invention is used in underground tunneling where a large amount of mud and sand are present. The L-shaped upper sealing dustproof ring 8-4 is made of high-molecular ultra-wear-resistant polyimide TPI material, which has the advantages of dimensional stability, high rigidity, good toughness, wear resistance, high temperature resistance, and corrosion resistance. It better stabilizes the sealing performance of the cutter hub 5, strictly prevents mud and sand particles from intruding into the cutter hub 5, and further protects the upper floating seal and upper tapered roller bearing 2 inside the cutter hub 5 for safe use. It is of practical significance to extend the service life of heavy-duty cutter head.

[0086] To prevent the loosening of the threads on the upper end cap 8-1 from affecting the overall preload of the upper tapered roller bearing 2, Figure 2 In the process, after the upper end cover 8-1 is pre-tightened in place, the locking piece 8-3 is inserted into the upper end of the cutter shaft 1 for peripheral beveling welding, and is positioned on the cutter shaft 1 and the upper end cover 8-1 for welding stop.

[0087] Combination Figure 3 As shown, the upper end cover 8-1 has two symmetrically distributed ZG1 / 4 holes for oil injection and gas testing, and is equipped with a single-hole pressure relief valve 8-5. When the internal pressure of the cutter hub 5 is greater than the external pressure by 3 bar, the internal pressure is automatically discharged to balance the internal pressure of the cutter hub 5 and protect the safe use of the floating seal inside the cutter hub 5.

[0088] Combination Figure 2 and Figure 4As shown, the lower cover assembly 9 includes a bearing support 9-1, a lower end cover 9-2, a lower oil seal bracket 9-3, a lower sealing dust ring 9-4, and several O-rings B9-5. The bearing support 9-1 is heat-fitted to the bottom of the cutter shaft 1 and abuts against the journal step 1-1. The bearing support 9-1 and the journal step 1-1 are sealed with O-rings B9-5. The bearing support 9-1 and the inner ring of the lower tapered roller bearing 3 are sealed with O-rings B9-5. The outer circumferential surface of the bearing support 9-1 is threaded. The lower end cover 9-2 is pre-tightened by the threaded connection, and O-rings B9-5 are arranged at the end face contact area.

[0089] It should be noted that the lower end cover 9-2 is provided with four evenly distributed pre-tightening wrench configuration holes 9-6 for pre-tightening with the bearing support seat 9-1. At the same time, it can facilitate quick disassembly and assembly of the lower end cover 9-2 and the lower oil seal bracket 9-3 during tool maintenance. This overcomes the disadvantages of the previous limitation that the end cover 9-2 and the lower floating seal 11 could only be removed by pressing down the cutter shaft 1. On the one hand, the interference fit between the cutter shaft 1 and the inner sleeve of the tapered roller bearing gradually decreases due to wear, resulting in low pre-tightening force. This leads to axial slippage of the tapered roller bearing under the high-load rolling of the hob. After a long time, the hob ring 6 wears unevenly and the inner sleeve of the tapered roller bearing wears abnormally and severely. On the other hand, the combined design and assembly method of the lower end cover 9-2 is beneficial for the hob to ensure normal rolling rock breaking while allowing for quick assembly and disassembly to analyze the internal condition of the hob hub 5 and quickly repair and replace the lower floating seal 11 and other seals.

[0090] In this embodiment, as Figure 4 As shown, the lower oil seal bracket 9-3 is disposed inside the lower end cover 9-2, and the lower floating seal 11 is disposed on the lower oil seal bracket 9-3; the end face between the lower oil seal bracket 9-3 and the blade hub 5 is sealed with two O-rings B9-5.

[0091] Furthermore, the lower oil seal bracket 9-3 is made of 42CrMo tempered material, precision machined, and then subjected to a 0.7mm nitriding process on the surface. Alternatively, the tempered part is rough machined and then induction hardened on the outer bevel to improve the surface wear resistance. Finally, the internal dimensions are precision machined to complete the design dimensions.

[0092] Furthermore, such as Figure 4 As shown, the lower end cover 9-2 and the lower oil seal bracket 9-3 are statically frictionally stepped sealed by the lower sealing dust ring 9-4 during the assembly process. This enhances the sealing effect without affecting the starting torque and maximizes the resistance to mud and sand erosion. An O-ring B9-5 is also added between the two and sealed above the lower sealing dust ring 9-4.

[0093] Among them, the L-shaped lower sealing dust ring 9-4 is made of high-molecular ultra-wear-resistant polyimide TPI material, which has the advantages of dimensional stability, high rigidity, good toughness, wear resistance, high temperature resistance, and corrosion resistance. It better stabilizes the sealing performance of the cutter hub 5, strictly prevents mud and sand particles from intruding into the cutter hub 5, and further protects the lower floating seal 11 and the lower tapered roller bearing 3 inside the cutter hub 5 for safe use. It is of practical significance to extend the service life of heavy-duty hobs.

[0094] Example 1

[0095] The main metal element mass percentages of the heavy shield tunnel cutterhead ring 6 in this embodiment are as follows: C: 0.56%, Si: 0.68%, Mn: 0.35%, Cr: 5%, Mo: 1.5%, W: 0.45%, V: 0.7%, P / S: 0.013, Ni: 2.8%, Cu: 0.096%, with the remainder being Fe. Its heat treatment process includes: high-temperature diffusion and multi-directional forging of the steel ingot obtained from the smelting of the aforementioned metal elements at 1250℃; repeated upsetting and drawing into round steel during billet preparation; forging and refining + blanking and rolling into a ring + secondary refinement + spheroidizing annealing + rough machining followed by composite heat treatment + vacuum quenching and tempering heat treatment; to prevent surface decarburization of the cutterhead ring 6 during quenching heating, the cutterhead ring 6 is vacuum quenched at 1030℃. 5h; the quenched blade ring 6 should be heat treated promptly, with 3 tempering heat treatments at 350℃. 3h 2 times; 535℃ 5h The overall hardness after one and three tempering processes is HRC59, HRC60, and HRC62, respectively.

[0096] The ultra-fine refining of the forged round includes: step heating to 1050℃ and holding for 3 hours, followed by water quenching and air cooling, repeated alternately. The water quenching and air cooling times are adjusted according to the diameter and length of the forged round, cycling until the air cooling temperature reaches 150℃ after the last water quenching. The round is then immediately transferred to a trolley furnace set at 920℃ for heating and holding to ensure uniform heating for 5 hours, followed by furnace cooling to approximately 720℃ and holding for 6 hours. Finally, it is furnace cooled to 350℃ and removed from the furnace. The secondary refining steps are the same. The sample obtained after these steps has a grain size of 8.5. Figure 1 As shown.

[0097] Furthermore, the multi-directional forging includes: a multi-directional forging temperature of 1130℃ at the beginning and 900℃ at the end, with the reduction rate gradually decreasing from 40% to 30% to 20% to 10% to 5%, thereby stabilizing the heat source.

[0098] Furthermore, the composite heat treatment is a carbonitriding composite heat treatment process, with a diffusion layer depth of 1.1 mm and a diffusion layer strength. Carbonitriding is carried out at a temperature of 850℃, which can improve the wear resistance and contact fatigue resistance of the blade ring 6.

[0099] The specific spheroidizing annealing process involves heating the blade ring 6 to 880°C, then cooling it to 750°C in the furnace. After holding it at that temperature for 1 hour, the ring is heated to 880°C again and then cooled to 750°C in the furnace.

[0100] The obtained tool ring was tested, and the results are as follows: Figure 12 As shown, the cutter ring was mounted on the hob and tested, and the results are as follows. Figures 9-11 As shown, the heavy-duty shield cutterhead ring has the best mechanical properties and the wear resistance of ultra-high permeability layer, making it perfectly suited to the technical configuration requirements of large shields, large diameter, and high load cutterheads.

[0101] Example 2

[0102] The main metal element mass percentages of the heavy shield tunnel cutterhead ring 6 in this embodiment are as follows: C: 0.48%, Si: 0.68%, Mn: 0.35%, Cr: 5%, Mo: 0.9%, W: 0.45%, V: 0.85%, P / S: 0.013, Ni: 3.6%, Cu: 0.096%, with the remainder being Fe. Its heat treatment process includes: high-temperature diffusion and multi-directional forging of the steel ingot obtained by smelting the aforementioned metal elements at 1250℃; repeated upsetting and drawing into round steel during billet preparation; forging and refining + blanking and rolling into a ring + secondary refinement + spheroidizing annealing + rough machining followed by composite heat treatment + vacuum quenching and tempering heat treatment; to prevent surface decarburization of the cutterhead ring 6 during quenching heating, the cutterhead ring 6 is vacuum quenched at 1030℃. 4h; the quenched blade ring 6 should be heat-treated promptly, with 3 tempering heat treatments at 350℃. 3h 2 times; 530℃ 5h 1 time.

[0103] The ultra-fine refining of the forged round includes: heating and holding at 1050℃ in stages for 3 hours, followed by water quenching and air cooling, repeating the process alternately. The water quenching time and air cooling time are adjusted according to the diameter and length of the forged round. The process is repeated until the air cooling temperature reaches 180℃ after the last water quenching. Then, the round is immediately transferred to a trolley furnace set at 920℃ for heating and holding to ensure uniform heating. After holding at this temperature for 6 hours, the round is cooled to approximately 740℃ in the furnace and held for 6 hours. After cooling to 350℃ in the furnace, the round is removed from the furnace. The secondary refining process is the same as described above.

[0104] Furthermore, the multi-directional forging includes: a multi-directional forging temperature of 1140℃ at the beginning and 910℃ at the end, with the reduction rate gradually decreasing from 40% to 30% to 20% to 10% to 5%, thereby stabilizing the heat source.

[0105] Furthermore, the composite heat treatment is a carbonitriding composite heat treatment process, with a diffusion layer depth of 1.2 mm and a diffusion layer strength. Carbonitriding is carried out at a temperature of 860℃, which can improve the wear resistance and contact fatigue resistance of the blade ring 6.

[0106] The specific spheroidizing annealing process is as follows: the blade ring 6 is heated to 890°C and then cooled to 755°C in the furnace. After holding at this temperature for 1 hour, it is heated to 890°C again and then cooled to 755°C in the furnace.

[0107] Example 3

[0108] The main metal element mass percentages of the heavy shield tunnel cutterhead ring 6 in this embodiment are as follows: C: 0.48%, Si: 0.68%, Mn: 0.47%, Cr: 5.6%, Mo: 0.9%, W: 0.56%, V: 0.7%, P / S: 0.013, Ni: 2.8%, Cu: 0.085%, with the remainder being Fe. Its heat treatment process includes: high-temperature diffusion and multi-directional forging of the steel ingot obtained by smelting the aforementioned metal elements at 1250℃; repeated upsetting and drawing into round steel during billet preparation; forging and refining + blanking and rolling into a ring + secondary refinement + spheroidizing annealing + rough machining followed by composite heat treatment + vacuum quenching and tempering heat treatment; the cutterhead ring 6 is vacuum quenched at 1030℃. 5h; the quenched blade ring 6 should be heat treated promptly, with 3 tempering heat treatments at 350℃. 3h 2 times; 530℃ 5h 1 time.

[0109] The ultra-fine refining of the forged round includes: heating and holding at 1050℃ in stages for 3 hours, followed by water quenching and air cooling, repeating the process alternately. The water quenching time and air cooling time are adjusted according to the diameter and length of the forged round. The process is repeated until the air cooling temperature reaches 200℃ after the last water quenching. Then, the round is immediately transferred to a trolley furnace set at 920℃ for heating and holding to ensure uniform heating. After holding at 720℃, the round is cooled to 765℃ in the furnace and held for 7 hours. After holding at 765℃, the round is cooled to 350℃ in the furnace and removed from the furnace. The secondary refining process is the same as above.

[0110] Furthermore, the multi-directional forging includes: a multi-directional forging temperature of 1150℃ at the beginning and 900℃ at the end, with the reduction rate gradually decreasing from 40% to 30% to 20% to 10% to 5%, thereby stabilizing the heat source.

[0111] Furthermore, the composite heat treatment is a carbonitriding composite heat treatment process, with a diffusion layer depth of 1.3 mm and a diffusion layer strength of 870℃, which can improve the wear resistance and contact fatigue resistance of the blade ring 6.

[0112] The specific spheroidizing annealing process involves heating the blade ring 6 to 900°C, then cooling it to 760°C in the furnace and holding it at that temperature for 1 hour. After that, the temperature is reheated to 900°C and then cooled to 760°C in the furnace and held at that temperature.

[0113] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A heavy-duty shield tunneling cutterhead ring, characterized in that, The heavy-duty shield tunnel cutterhead ring comprises the following elements by mass percentage: C: 0.48%–0.56%, Si: 0.68%–0.78%, Mn: 0.35%–0.47%, Cr: 5%–5.6%, Mo: 0.9%–1.5%, W: 0.45%–0.56%, V: 0.7%–0.85%, P / S: 0.013, Ni: 2.8%–3.6%, Cu: 0.085%–0.096%, with the remainder being Fe; Its preparation process includes: smelting the steel ingots obtained by the constituent elements and subjecting them to high-temperature diffusion at 1250℃ + multi-directional forging, repeatedly upsetting and drawing them into round bars during billet opening + forging and ultra-refining + blanking, forging and rolling into billets + secondary refinement + spheroidizing annealing + rough machining followed by composite heat treatment + vacuum quenching + tempering heat treatment. The vacuum quenching is 1030℃ for 3-5 hours; the tempering heat treatment is 350℃ for 3 hours twice and (530-540)℃ for 5 hours once. The composite heat treatment is a carbonitriding composite heat treatment process, with a diffusion layer depth of 1.1-1.3 mm and a diffusion layer strength of 850℃-870℃.

2. The heavy-duty shield tunneling cutterhead ring according to claim 1, characterized in that, The process of refining the forged round shape includes: step heating to 1050℃ and holding for 3 hours, followed by water quenching and air cooling, repeating this alternating process until the air cooling temperature is 150℃-200℃ after the last water quenching. Then, the round is immediately transferred to a trolley furnace set at 920℃ for heating and holding to ensure uniform heating. After holding for 5-7 hours, the round is cooled to 765℃-720℃ with the furnace and held for 6-7 hours. Finally, it is cooled to 350℃ with the furnace before being removed from the furnace.

3. The heavy-duty shield tunneling cutterhead ring according to claim 2, characterized in that, The multi-directional forging process includes: a starting forging temperature of 1130-1150℃, a final forging temperature of 900±10℃, and a reduction rate that gradually decreases from 40%-30%-20%-10%-5%.

4. A heavy-duty shield tunneling disc cutterhead, characterized in that, include: The cutter shaft (1) has a journal step (1-1) and is threaded along the outer circumference of the cutter shaft (1); An upper tapered roller bearing (2) and a lower tapered roller bearing (3) are sleeved on the cutter shaft (1), and the upper tapered roller bearing (2) and the lower tapered roller bearing (3) are separated by a spacer (4); A cutter hub (5) fitted outside the upper tapered roller bearing (2) and the lower tapered roller bearing (3); At least one cutter ring (6) is sleeved on the outer circumferential direction of the cutter hub (5), and a retaining ring (7) is provided on one side of the cutter ring (6), and the retaining ring (7) is fixed to the cutter hub (5); the cutter ring (6) is the heavy shield rolling cutter ring according to any one of claims 1-3; The upper cover assembly (8) and the lower cover assembly (9) are provided at both ends of the axial direction of the cutter shaft (1). An upper floating seal (10) is provided between the upper cover assembly (8) and the upper tapered roller bearing (2); a lower floating seal (11) is provided between the lower cover assembly (9) and the lower tapered roller bearing (3).

5. The heavy-duty shield tunneling disc cutterhead according to claim 4, characterized in that, The spacer ring (4) is made of spring steel and has an H-shaped profile.

6. The heavy-duty shield tunneling disc cutterhead according to claim 4, characterized in that, The upper cover assembly (8) includes an upper end cover (8-1), an upper oil seal bracket (8-2), a locking piece (8-3), an upper sealing dust ring (8-4), a pressure relief valve (8-5), and several O-ring seals A (8-6). The upper end cover (8-1) is pre-tightened with the cutter shaft (1) at the large end face of the upper tapered roller bearing (2) using an internal thread. During the pre-tightening process of the upper tapered roller bearing (2), an O-ring A (8-6) is installed between the upper end cover (8-1) and the large end face of the inner sleeve of the upper tapered roller bearing (2) to seal the end face. The upper end cover (8-1) is pre-tightened with the cutter shaft (1) at the large end face of the upper tapered roller bearing (2) using an internal thread. The upper oil seal bracket (8-2) is located inside the upper end cover (8-1), and the upper floating seal (10) is located on the upper oil seal bracket (8-2); the end face between the upper oil seal bracket (8-2) and the blade hub (5) is sealed with at least two O-ring seals A (8-6); During the assembly process, the upper end cover (8-1) and the upper oil seal bracket (8-2) are sealed by the upper sealing dust ring (8-4) through a static friction gap stepped seal. After the upper end cover (8-1) is pre-tightened, the locking piece (8-3) is fitted onto the upper end of the cutter shaft (1) for peripheral beveling welding.

7. The heavy-duty shield tunneling disc cutterhead according to claim 6, characterized in that, An O-ring A (8-6) is added between the upper end cover (8-1) and the upper oil seal bracket (8-2) to seal below the upper sealing dust ring (8-4).

8. The heavy-duty shield tunneling disc cutterhead according to claim 4, characterized in that, The lower cover assembly (9) includes a bearing support seat (9-1), a lower end cover (9-2), a lower oil seal bracket (9-3), a lower sealing dust ring (9-4), and several O-rings B (9-5). The bearing support seat (9-1) is heat-fitted to the bottom of the cutter shaft (1) and abuts against the journal step (1-1). The bearing support seat (9-1) and the journal step (1-1) are sealed with O-ring seals B (9-5). The bearing support seat (9-1) and the inner ring of the lower tapered roller bearing (3) are sealed with O-ring seals B (9-5). The outer circumferential surface of the bearing support seat (9-1) is threaded. The lower end cover (9-2) is pre-tightened with the threaded connection and O-ring seals B (9-5) are arranged at the end face contact part. The lower oil seal bracket (9-3) is located inside the lower end cover (9-2), and the lower floating seal (11) is located on the lower oil seal bracket (9-3); the end face between the lower oil seal bracket (9-3) and the blade hub (5) is sealed with at least two O-rings B (9-5). During the assembly process, the lower end cap (9-2) and the lower oil seal bracket (9-3) are sealed by the lower sealing dust ring (9-4) through a static friction gap stepped seal.

9. A TBM tunneling machine having a heavy-duty shield disc cutterhead as described in any one of claims 4-8.

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