Cutter for TBM (Tunnel Boring Machine) as well as production method and repair method of cutter

Abstract

The invention belongs to the technical field of TBM cutters, and particularly relates to a TBM cutter and a production method and repairing method thereof.The TBM cutter comprises a cutter body and a cutter sheath, the cutter sheath comprises a first sheath and a second sheath which are fixedly connected, and the cutter body is arranged in a closed space defined by the first sheath and the second sheath; the tool body comprises a tool base body and a tool outer ring, the room-temperature Charpy impact energy of the tool base body is larger than or equal to 30 J, the hardness of the tool outer ring is larger than or equal to 65 HRC, and the room-temperature Charpy impact energy is larger than or equal to 20 J. The cutter is prepared by adopting a structural form with tough inside and hard outside, so that the inner ring part of the cutter ring is ensured to have better toughness, the outer ring is ensured to have high hardness and good wear resistance, the cutter base body and the cutter outer ring powder material can be perfectly attached to each other through the sheath design, and the cutter base body and the cutter outer ring powder material can be tightly pressed through the hot isostatic pressing mode. And meanwhile, the compactness of the cutter ring is improved, repair is convenient, and repeated utilization is achieved.

Description

Technical Field

[0001] This invention belongs to the field of TBM cutting tool technology, specifically relating to a TBM cutting tool and its production and repair methods. Background Technology

[0002] Currently, tunnel boring machines (TBMs) are being used more and more widely in tunnel excavation projects, greatly improving the speed of tunnel construction. The cutter head, cutter blade, and side cutter blade are key components of the TBM for rock breaking. They come into direct contact with the rock and experience wear. Their performance and number of uses directly affect the efficiency and cost of tunnel construction.

[0003] Most cutter rings are currently manufactured as a single piece using mold steel, and their performance depends on the material of the mold steel. Currently, the main materials for cutter rings are H13 steel and DC53 steel, which cannot simultaneously achieve both wear resistance and impact resistance.

[0004] Meanwhile, even after the tool rings and alloy tools have reached their wear limit, two-thirds of the substrate remains, but the project has to discard them as scrap, resulting in waste. In the prior art, Chinese invention patent application publication number CN108817398A: A production process for spray-formed composite material TBM blade rings, discloses a method for preparing composite blade rings by spray forming. It achieves metallurgical bonding by spraying molten metal droplets onto the inner ring substrate of the blade ring. However, the density after spraying cannot reach 100% and forging is still required. Forging will affect the interface between the inner and outer layers, thus affecting the performance.

[0005] Chinese invention patent application CN113441723B: A super wear-resistant shield tunneling machine cutter ring and its manufacturing method. It discloses a method for combining cemented carbide with the cutter ring. However, this method suffers from the poor cutting edge shape of the cemented carbide, making it prone to breakage in impact formations, resulting in high maintenance costs and reduced construction efficiency.

[0006] Chinese invention patent application CN112157242B, entitled "A Composite Hob Cutter Ring and Its Preparation Method," discloses a centrifugally cast gradient composite cutter ring. However, this method tends to result in poor uniformity and consistency of the outer ring, making it difficult to obtain cutter rings with identical performance.

[0007] In conclusion, none of the above solutions can effectively solve the aforementioned problems. Summary of the Invention

[0008] This invention addresses the problem that existing cutter ring materials cannot simultaneously achieve both wear resistance and toughness, and that residual materials after wear are wasteful and cannot be reused. It provides a TBM (Turbine Machine Tool) cutter, its manufacturing method, and a repair method. The cutter is manufactured using an inner tough and outer hard structure, ensuring good toughness in the inner ring while maintaining high hardness and wear resistance in the outer ring. A sheathing design allows the cutter body and the outer ring powder material to fit perfectly together. Hot isostatic pressing (HIP) forms a metallurgical bond between the powder material and the inner ring, increasing the cutter ring's density and further enhancing its wear resistance. Furthermore, the invention is easy to repair, requiring no replacement of the cutter body and enabling reuse.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: A TBM cutting tool includes a tool body and a tool sleeve. The tool sleeve includes a first sleeve and a second sleeve fixedly connected to each other. The tool body is disposed within a closed space enclosed by the first sleeve and the second sleeve. The tool body includes a tool base and a tool outer ring. The tool base has a room temperature Charpy impact energy greater than or equal to 30J. The tool outer ring has a hardness greater than or equal to 65HRC and a room temperature Charpy impact energy greater than or equal to 20J. The tool outer ring, made of wear-resistant material, reduces the wear of the tool due to friction between the tool and external materials during use. The tool base, made of high-toughness material, ensures the impact resistance of the tool, thereby effectively guaranteeing the tool's performance and service life.

[0010] Preferably, the tool sheath is made of 304 stainless steel.

[0011] Preferably, the tool sleeve has a powder injection hole corresponding to the outer ring of the tool.

[0012] A method for manufacturing cutting tools for TBMs, comprising the following steps: Step 1: Prepare the tool substrate; Step 2: Place the prepared tool substrate into the tool sleeve, and weld the joint between the first sleeve and the second sleeve to fix it. Step 3: Add powder material into the tool sleeve through the powder injection hole, and then weld the powder injection hole to seal it. Step 4: The cutting tool is hot isostatically pressed at 980-1300℃ and 90-200MPa for 2-4 hours to form the powder material into the outer ring of the cutting tool, and the outer ring of the cutting tool is fixedly connected to the cutting tool base.

[0013] Preferably, the tool substrate is prepared using 42CrMo.

[0014] A method for repairing TBM cutting tools, comprising the following steps: Step 1: Remove the tool sleeve from the worn tool after use, and use sandblasting to remove surface rust and stains from the tool. Step 2: Replace the tool sleeve with a new one, and inject powder material into it through the powder injection hole on the new tool sleeve. After the powder injection is completed, weld the powder injection hole shut. Step 3: Perform hot isostatic pressing on the tool after powder injection. Perform hot isostatic pressing at 980-1300℃ and 90-200MPa for 2-4 hours to complete the tool repair.

[0015] The beneficial effects of the present invention through the above technical solution are as follows: 1. The cutting tool prepared by hot isostatic pressing in this invention takes into account both wear resistance and toughness, improves the density of the wear-resistant part of the outer ring by 100%, and improves the overall performance of the cutting tool. At the same time, during repair, the method of repairing by supplementing powder material makes it possible to repair cutting tools with large wear, realizes the reuse of the unworn part of the cutting tool, increases the number of times the base material of prop products such as cutting tool rings and alloy props can be used, saves resources and reduces waste.

[0016] 2. This invention achieves both high toughness in the core of the cutting tool ring (room temperature Charpy impact energy KV2≥30J; more than 3 times higher than high carbon H13 impact toughness) and high hardness in the outer ring (surface hardness≥65HRC, room temperature Charpy impact energy KV2≥20J; 30% higher than high carbon H13 impact toughness) through a gradient material design of "inner toughness and outer hardness". This solves the technical contradiction that hardness and toughness cannot be achieved simultaneously in traditional single-material cutting tools.

[0017] 3. This invention uses hot isostatic pressing to form a dense metallurgical bond between the powder material and the matrix, with an interfacial shear strength ≥500 MPa (more than 200% higher than the traditional brazing process), which significantly reduces the risk of delamination failure during use.

[0018] 4. This invention can repair worn tools and extend their service life to 85%-90% of that of new tools, reduce tool ring material costs by 20%-50%, and reduce tool waste by 60%-70%, which is in line with the concept of green manufacturing.

[0019] 5. The repair layer of this invention has a density of >99.5% (compared to 95%-98% for laser cladding). In hard rock formations with uniaxial compressive strength >150 MPa, the tool wear rate is reduced by 35%-45%, and the continuous tunneling mileage of the tunnel boring machine is extended by 20%-30%.

[0020] 6. The tool structure, preparation method and repair method of the present invention have a wide range of applications. Through modular encapsulation design, it can be adapted to different tool types such as hobs, scrapers and edge scrapers. The repair dimensional accuracy can be controlled up to ±0.1 mm, which meets the needs of complex working conditions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention when the cutting tool is a cutter ring. Figure 1 .

[0022] Figure 2 This is a schematic diagram of the structure of the present invention when the cutting tool is a cutter ring. Figure 2 .

[0023] Figure 3 This is a schematic diagram of the structure of the cutting tool of the present invention when it is an alloy tool. Figure 1 .

[0024] Figure 4 This is a schematic diagram of the structure of the cutting tool of the present invention when it is an alloy cutting tool. Figure 2 .

[0025] The labels in the attached diagram are as follows: 1 is the outer ring of the tool, 2 is the tool body, 3 is the tool sleeve, and 4 is the powder injection port. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: like Figures 1-4 As shown, this embodiment provides a TBM cutting tool, including a cutting tool body and a cutting tool sleeve 3. The cutting tool sleeve 1 includes a first sleeve and a second sleeve that are fixedly connected to each other. The cutting tool body is disposed in the closed space enclosed by the first sleeve and the second sleeve. The cutting tool body includes a cutting tool base 2 and a cutting tool outer ring 1. The cutting tool base 2 has a room temperature Charpy impact energy greater than or equal to 30J, and the cutting tool outer ring 1 has a hardness greater than or equal to 65HRC and a room temperature Charpy impact energy greater than or equal to 20J. This achieves the form of internal toughness and external hardness of the cutting tool, which ensures that the cutting tool base 2 has good toughness and that the cutting tool outer ring 1 has high hardness and good wear resistance.

[0027] The tool sleeve 3 is made of 304 stainless steel. The tool sleeve 3 has a powder injection hole 4 corresponding to the outer ring 1 of the tool. During preparation, the tool body 2 is wrapped in the tool sleeve 3, and the powder material is injected into the tool sleeve 3 through the powder injection hole 4. Then the powder injection hole 4 is welded shut. The metallurgical bonding between the powder material and the tool body 2 is achieved by hot isostatic pressing. The tool sleeve 3 makes the tool body 2 fit perfectly with the outer ring 1 of the tool.

[0028] A method for manufacturing cutting tools for TBMs, comprising the following steps: Step 1: Prepare the tool substrate 2; More specifically, the tool substrate 2 is made of 42CrMo or 40CrNiMo, or other materials with high toughness, to ensure that the room temperature Charpy impact energy KV2 of the tool ring substrate 2 is ≥30J.

[0029] Step 2: Place the prepared tool base 2 into the tool sleeve 3, and weld the joint between the first sleeve and the second sleeve to fix it. More specifically, the tool sleeve 3 is based on the tool structure design and matches the shape of the formed tool. It adopts an assembled sleeve design (i.e., the first sleeve and the second sleeve are combined to wrap the tool base 2), which makes it more convenient to accommodate the prepared tool base 2.

[0030] Step 3: Add powder material into the tool sleeve 3 through the powder injection hole 4, and then weld and seal the powder injection hole 4. The powder material is injected into the tool sleeve 3 through the powder injection hole 4. Utilizing the characteristics of the powder, it fills the gap between the tool substrate 2 and the inner wall of the tool sleeve 3, and at the same time, it ensures that the powder material is fully bonded to the tool substrate 2. By using hot isostatic pressing, the powder material is metallurgically bonded to the inner ring, while simultaneously increasing the density of the blade ring, thus giving it better wear resistance.

[0031] Step 4: The cutting tool is hot isostatically pressed at 980-1300℃ and 90-200MPa for 2-4 hours to form the powder material into the outer ring 1 of the cutting tool, and the outer ring 1 of the cutting tool is fixedly connected to the cutting tool base 2. After the hot isostatic pressing process is completed, the formed tool outer ring 1 and the tool substrate 2 form a metallurgical bond, and the density of the tool outer ring is greater than 90%, the macro hardness is HRC greater than 65, and the room temperature Charpy impact energy KV2 ≥ 20J.

[0032] A method for repairing TBM cutting tools, comprising the following steps: Step 1: Remove the tool sleeve 3 from the worn tool after use, and use sandblasting to remove surface rust and stains from the tool. After actual use, the wear of the tool is mainly concentrated on the outer ring 1 of the tool (the outer ring 1 is on one side of the tool body 2) and the corresponding tool sleeve 3. Therefore, the repair is mainly focused on the wear part of the outer ring 1 of the tool. By removing rust and stains from the surface of the prop, the metallurgical bonding between the new powder material and the outer ring 1 of the original blade after hot isostatic pressing is avoided.

[0033] Step 2: Replace the tool sleeve 3 with a new one, and inject powder material into it through the powder injection hole 4 on the replaced tool sleeve 3. After the powder injection is completed, weld and seal the powder injection hole 4. By replacing the tool sleeve 3, the powder material can be reinjected through the powder injection hole 4, and the powder material fully fills the gap caused by the wear of the original tool outer ring 1.

[0034] Step 3: Perform hot isostatic pressing on the powder-filled tool. Perform hot isostatic pressing at 980-1300℃ and 90-200MPa for 2-4 hours to complete the tool repair. By re-hot isostatic pressing, a metallurgical bond is formed between the new powder material and the original tool outer ring 1, ensuring the integral connection of the repaired tool outer ring 1 and guaranteeing the density and connection strength of the newly repaired tool outer ring 1. This enables the multiple utilization of the residual tool outer ring 1 material and tool matrix 2 after wear, making the tool wear-resistant structure denser and greatly improving the tool's service life. It has a greater technical advantage in strata with high rock hardness, increases the number of times the tool material can be used, reduces material costs, and has a significant economic advantage.

[0035] It should be noted that during hot isostatic pressing, the powder material of components such as the roller cutter, scraper, and side scraper can be replaced with other wear-resistant powder materials to achieve the same effect.

[0036] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included within the scope of the present invention.

Claims

1. A cutting tool for TBMs, characterized in that, The tool includes a tool body and a tool sleeve (3). The tool sleeve (1) includes a first sleeve and a second sleeve that are fixedly connected to each other. The tool body is provided in the closed space enclosed by the first sleeve and the second sleeve. The tool body includes a tool base (2) and a tool outer ring (1). The room temperature Charpy impact energy of the tool base (2) is greater than or equal to 30J. The hardness of the tool outer ring (1) is greater than or equal to 65HRC and the room temperature Charpy impact energy is greater than or equal to 20J.

2. The TBM cutting tool according to claim 1, characterized in that, The tool sheath (3) is made of 304 stainless steel.

3. A cutting tool for TBM according to claim 1, characterized in that, The tool sleeve (3) has a powder injection hole (4) corresponding to the outer ring (1) of the tool.

4. A method for manufacturing cutting tools for TBMs, characterized in that, The process for preparing the TBM cutting tool according to any one of claims 1-3 includes the following steps: Step 1, prepare the tool substrate (2); Step 2: Place the prepared tool base (2) into the tool sleeve (3) and weld the joint between the first sleeve and the second sleeve to fix it. Step 3: Add powder material into the tool sleeve (3) through the powder injection hole (4), and then weld and seal the powder injection hole (4). Step 4: The cutting tool is hot isostatically pressed at 980-1300℃ and 90-200MPa for 2-4 hours to form the powder material into the outer ring (1) of the cutting tool, and the outer ring (1) of the cutting tool is fixedly connected to the cutting tool base (2).

5. The method for manufacturing a cutting tool for a TBM according to claim 4, characterized in that, The tool substrate (2) is prepared using 42CrMo.

6. A method for repairing a TBM using a cutting tool, characterized in that, The method for repairing the TBM tool prepared according to claim 4 includes the following steps: Step 1: Remove the tool sleeve (3) from the worn tool after use, and use sandblasting to remove surface rust and stains from the tool. Step 2: Replace the tool sleeve (3) with a new one, and inject powder material into it through the powder injection hole (4) on the replaced tool sleeve (3). After the powder injection is completed, weld and seal the powder injection hole (4). Step 3: Perform hot isostatic pressing on the tool after powder injection. Perform hot isostatic pressing at 980-1300℃ and 90-200MPa for 2-4 hours to complete the tool repair.

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