Preparation process of composite cutter ring of shield tunneling machine

Abstract

The invention provides a shield tunneling machine composite cutter ring preparation technology, and belongs to the technical field of shield tunneling machine cutter ring preparation, and the shield tunneling machine composite cutter ring preparation technology comprises the following steps: 1, preparing Fe powder and metal or nonmetal and alloy powder thereof into mixed powder, and carrying out metallurgical molding treatment to prepare a composite wear-resistant body; 2, cutting the composite wear-resistant body into small sections, and then fixing the small sections in a cavity of a casting mold; 3, the outer surface of the small-section composite wear-resisting body is coated with nano reinforced particles; fourthly, molten steel of the cutter ring base material is poured into a cavity of the casting mold, and a cutter ring blank is manufactured; 5, the cutter ring blank is machined into a finished cutter ring; the abrasion resistance of the cutter ring is improved, meanwhile, good toughness is kept, the problem that a traditional cutter ring is prone to abrasion is solved, and the overall service life of the cutter ring is prolonged. And the second-phase particles are distributed between the wear-resistant body and the steel substrate in a dispersed state to form a hardness gradient, so that the structural stability of the cutter ring is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of shield machine cutter ring preparation, and more specifically, particularly relates to a shield machine composite cutter ring preparation process. Background Art

[0002] A shield machine is a tunnel boring machine that uses the shield method for construction. It consists of a shield body, a cutterhead, a drive system, slag transportation and segment assembly. The cutterhead is a component used to cut the soil and has a very important impact on the construction effect of the shield machine. The cutterhead includes a cutter ring, a panel, an excavation notch, a drive mechanism, etc. Since the cutter ring is directly exposed to the impact and wear of the rock, fatigue damage occurs to the cutter ring material, which in turn causes the initiation and expansion of cracks. In addition, the uneven force on various parts of the cutter ring during operation further aggravates the damage rate of the cutter ring, making the existing cutter ring extremely easy to be damaged, which directly affects the cutting effect, excavation conditions and excavation speed of the shield machine.

[0003] Therefore, in order to reduce the number of shutdowns and cutter ring replacements and reduce cutter ring loss, laser surface treated cutter rings and cladding cutter rings have appeared, which have alleviated the wear problem to a certain extent; later, cutter rings inlaid with cemented carbide have appeared. This method is to drill a hole on the outer diameter of the existing cutter ring, and then embed the cemented carbide head into the hole and fix it; although cemented carbide has a high hardness and can resist rock wear to a certain extent, it has poor toughness and is prone to cracking when subjected to impact loads, especially when the cutter ring base part connected to the cemented carbide undergoes structural changes due to wear, the cemented carbide head cannot maintain a good bonding strength with the base and will fall off quickly, which cannot effectively increase the life of the shield machine cutter ring; therefore, a method is needed to increase the life of the cutter ring and reduce construction costs. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a process for preparing a composite cutter ring of a shield machine to solve the technical problems in the prior art that traditional cutter rings of shield machines are easily worn, resulting in a short service life and high consumption.

[0005] The purpose and effect of the composite cutter ring preparation process of a shield machine of the present invention are achieved by the following specific technical means: A shield machine composite cutter ring preparation process comprises the following steps: Step 1: fully mix Fe powder with metal or non-metal and its alloy powder in a certain proportion to make a mixed powder, and perform metallurgical forming treatment on the mixed powder to make a composite wear-resistant body; Step 2: cutting the composite wear-resistant body into multiple groups of small composite wear-resistant bodies with a length of 20 mm to 80 mm, and then fixing the multiple groups of small composite wear-resistant bodies in the cavity of the casting mold; Step three: coating the outer surface of the small composite wear-resistant body with nano-reinforced particles; Step 4: pouring molten steel of the cutter ring matrix material into the cavity of the casting mold, melting the surface layer of the small section composite wear-resistant body and fusing it with the nano-reinforced particles in the matrix material, and after cooling, casting the small section composite wear-resistant body and the matrix material into one piece through the reinforced particles to make a cutter ring blank; Step 5: annealing, rough machining, heat treatment and finish machining the cutter ring blank to produce a finished cutter ring.

[0006] In a preferred embodiment, in step one, the metallurgical forming process includes drying the mixed powder and then loading it into a steel pipe, cold rolling it after sealing the ends, and then hot rolling it after heating.

[0007] In a preferred embodiment, the components of the mixed powder are as follows by weight: 60 to 70 parts of Fe powder and 30 to 40 parts of metal or non-metal and its alloy powder; the metal or non-metal and its alloy powder is two or more of SiC, SiN, ZrO2, WC, Al2O3, B, Cr, Ni, Mo, and diamond powder.

[0008] In a preferred embodiment, the cold rolling includes 3 to 12 cold rolling passes, and the hot rolling after heating includes heating to 900 to 1250° C. for hot rolling.

[0009] In a preferred embodiment, the metallurgical forming treatment includes loading the mixed powder into a mold for pressing and then sintering, and the sintering temperature is 900-1300°C; the pressing includes placing the mold containing the mixed powder into a hot pressing device for hot pressing and compounding, and the temperature of the hot pressing and compounding is 100-150°C, the pressure is 0.5-1.5MPa, and the pressure is maintained for 4-7 minutes after reaching the pressure.

[0010] In a preferred embodiment, in step 2, the small-segment composite wear-resistant body is fixed in the cavity of the casting mold by grid method or welding fixing ribs, the diameter of the small-segment composite wear-resistant body is 20mm to 50mm, and the spacing between multiple groups of the small-segment composite wear-resistant body is 10mm to 50mm.

[0011] In a preferred embodiment, in step three, the nano-reinforced particles are one or more of ZrO2, WC, Al2O3, Ni powder, and high-speed steel powder, and are wrapped with phosphorus Fe powder to improve the wettability between the nano-reinforced particles and the molten steel.

[0012] In a preferred embodiment, the thickness of the coated nano-reinforced particles is 0.5 mm to 5 mm.

[0013] In a preferred embodiment, in step 4, the temperature of the molten steel is 1560-1750° C., and the process is carried out under a gas protection environment and negative pressure.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. A composite wear-resistant body is made by fully mixing Fe powder with metal or non-metal and its alloy powder, and undergoing a series of metallurgical forming treatments such as drying, cold rolling, hot rolling, etc. Then, nano-reinforced particles are coated on the outer surface of the wear-resistant body to further enhance the hardness. The high hardness allows the cutter ring to be fearless of the violent scraping and strong impact of rocks during shield machine excavation, and the wear resistance is significantly enhanced; at the same time, the cutter ring still retains good toughness, effectively avoiding cracks caused by uneven force and excessive impact, solving the problem of easy wear of traditional cutter rings, extending the overall service life of the cutter ring, and reducing construction delays and cost losses caused by frequent replacement of cutter rings.

[0015] 2. The structural stability of the cutter ring is enhanced by coating nano-reinforced particles; after a small section of the composite wear-resistant body is fixed in the casting mold cavity, 0.5-5 mm thick nano-reinforced particles wrapped with phosphorus Fe powder are applied, and then 1560-1750°C molten steel is poured in a gas protection environment and negative pressure state; in this process, the nano-reinforced particles are dispersed between the wear-resistant body and the steel matrix to shape a composition gradient transition area, which can not only reduce the interface stress between the wear-resistant body and the matrix, but also form a hardness gradient through the dispersed distribution of the second phase particles, thereby improving the impact resistance and cracking resistance of the overall structure, and further ensuring the structural stability of the cutter ring during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flowchart of the steps of a shield machine composite cutter ring preparation process. DETAILED DESCRIPTION

[0017] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with the accompanying drawings and examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0018] Example 1: Please refer to Figure 1 As shown, the present invention provides a shield machine composite cutter ring preparation process, comprising the following steps: Step 1: First, iron powder is fully mixed with metal or non-metal and its alloy powder in a certain proportion to make a mixed powder; then the mixed powder is subjected to metallurgical forming treatment to finally produce a composite wear-resistant body with excellent wear resistance; Step 2: Use cutting equipment to process the composite wear-resistant body, cut it into small sections of composite wear-resistant body with a length of 20mm to 80mm, and then fix multiple groups of small sections of composite wear-resistant body in the cavity of the casting mold. If it is fixed in a grid manner, accurately install the prefabricated grid frame in the cavity. The frame is made of high-temperature resistant and high-strength alloy material, and the small sections of composite wear-resistant body are embedded in the grid space one by one, with precise positioning and stability; if the welding fixed rib method is selected, accurately weld the alloy fixed ribs at the predetermined position of the cavity, and the rib spacing and length match the size of the small section of composite wear-resistant body, and then carefully weld the small section of wear-resistant body. The diameter of the small section of composite wear-resistant body is 20mm to 50mm, and the spacing of multiple groups of small sections of composite wear-resistant body is 10mm to 50mm, to ensure the uniformity of subsequent pouring; Step 3: The outer surface of the small composite wear-resistant body fixed in the casting mold is coated with nano-reinforced particles; the nano-reinforced particles are one or more of ZrO2, WC, Al2O3, Ni powder, and high-speed steel powder, and the nano-particles are coated with iron phosphide powder to improve the affinity and wettability between the particles and the subsequent poured steel liquid; the specific coating process is to mix the prepared nano-reinforced particles and iron phosphide powder evenly, and then use a soft brush or spray gun to start from one end of the small composite wear-resistant body in the mold and gradually The other end is evenly coated or sprayed, and finally a coating with a thickness of 0.5 mm to 5 mm is formed; this coating treatment not only further improves the surface hardness of the small section of composite wear-resistant body and enhances its wear resistance, but also does not affect the good toughness of its base material. It not only allows the cutter ring to resist the severe abrasion and impact of the rock during the tunneling process of the shield machine, but also effectively avoids the cracking problem caused by uneven force or excessive impact, thereby significantly extending the service life of the cutter ring and reducing the construction delay and cost loss caused by frequent replacement of the cutter ring; Step 4: Pour the molten steel of the cutter ring matrix material into the cavity of the casting mold. During this process, the small section of composite wear-resistant body fixed in the mold melts under the action of high-temperature molten steel, and is fused into the matrix material together with the nano-enhanced particles previously coated on the surface; after cooling and solidification, these small sections of composite wear-resistant body and matrix material are cast as one, and finally the blank of the cutter ring is made; when pouring molten steel, its temperature is controlled at 1560-1750℃, and the whole process is carried out under gas protection environment and negative pressure. Under this process condition, those nano-enhanced particles can form a composition gradient transition zone between the wear-resistant body and the steel matrix. This gradient transition zone can not only reduce the interface stress between the wear-resistant body and the matrix, but also form a hardness gradient through the dispersion distribution of the second phase particles, thereby improving the impact resistance and cracking resistance of the overall structure, and further ensuring the structural stability of the cutter ring during use; Step 5: Anneal, rough process, heat treat and finish the cutter ring blank to make the finished cutter ring; annealing treatment is used to slowly release the residual stress inside the cutter ring blank to improve the cutting processability and prevent deformation and cracking during subsequent processing; in the rough process stage, the cutter ring blank is cut by CNC lathe and milling machine to remove excess material; in the heat treatment stage, the rough-processed cutter ring is moved to the heat treatment equipment to optimize the organizational structure of the cutter ring and enhance the hardness and toughness; in the finishing stage, grinders and honing machines are used to grind the surface of the cutter ring to eliminate minor defects, so that the cutter ring reaches the specified accuracy and finish to make the finished cutter ring.

[0019] In step 1, the metallurgical forming process includes drying the mixed powder and then loading it into a steel pipe. The drying process can remove moisture in the powder to avoid fluctuations in material performance or processing failures caused by water vapor in subsequent processing; cold rolling after sealing the ends, and then hot rolling after heating. The components of the mixed powder are as follows by weight: 60 to 70 parts of Fe powder, which, as a basic component, can give the material basic toughness and strength support, which is conducive to subsequent processing and forming; 30 to 40 parts of metal or non-metal and its alloy powder; the metal or non-metal and its alloy powder is two or more of SiC, SiN, ZrO2, WC, Al2O3, B, Cr, Ni, Mo, diamond powder There are many kinds of cold rolling. The cold rolling mill puts the sealed steel pipe on the cold rolling mill. The cold rolling mill applies pressure through the rollers and rolls the steel pipe step by step according to the set 3 to 12 passes, so that the mixed powder is compacted tightly under pressure, the internal organizational structure is reshaped, the grains are deformed, and the hardness and strength are improved. After the cold rolling is completed, the steel pipe and the internal material are transferred to the heating furnace and heated to 900-1250℃. If the temperature is too low, the material will not soften properly and the ideal hot rolling effect cannot be achieved. If the temperature is too high, the material will be overburned and the performance will deteriorate. After reaching the predetermined temperature, the hot rolling process is quickly entered. The hot rolling mill acts again through the rollers, and with the help of the good plasticity of the material at high temperature, the grains are further refined and the organization is homogenized, so that the performance of the composite wear-resistant body is better.

[0020] The metallurgical forming process includes placing the mixed powder into a mold for pressing and then sintering, and the sintering temperature is 900-1300°C; pressing includes placing the mold containing the mixed powder into a hot pressing device for hot pressing and compounding, and the hot pressing and compounding temperature is 100-150°C and the pressure is 0.5-1.5MPa, and the pressure is maintained for 4-7 minutes after reaching the pressure.

[0021] Embodiment 2: Based on the shield machine composite cutter ring preparation process provided in Embodiment 1 of the present application, Embodiment 2 of the present application proposes a shield machine composite cutter ring preparation process. This Embodiment 2 is only a preferred method of Embodiment 1, and the implementation of Embodiment 2 will not affect the independent implementation of Embodiment 1. The second Embodiment 2 of the present invention will be further described below.

[0022] The metallurgical forming process includes loading the mixed powder into the mold, tapping the outer wall of the mold during loading to assist the powder to evenly sink and fill the cavity; moving the mold with the mixed powder to the hot pressing equipment, heating it to 100-150°C, and simultaneously applying a pressure of 0.5-1.5MPa. When the pressure reaches the standard, the pressure is maintained for 4-7 minutes. During this period, the powder particles adhere to each other and are initially consolidated under the dual effects of warmth and pressure; after the hot pressing is completed, the mold is moved to the sintering furnace, and the sintering temperature is 900-1300°C. The atoms between the powder particles are fully diffused and metallurgically bonded, the pores are eliminated, and the density and strength are increased to form a composite wear-resistant body.

[0023] Compared with the cold rolling and hot rolling methods in Example 1, this Example 2 is performed by loading the mixed powder into a mold for pressing and then sintering. The main difference is that more accurate shape control of the powder material can be achieved. Using the mold, the mixed powder can fit tightly into the mold cavity under pressure and is initially formed into a blank with regular size and uniform density. It can not only effectively avoid defects such as wrinkles and cracks that may be caused by uneven deformation of the material during the cold rolling process, but also control key dimensional parameters such as the thickness and diameter of the blank to make it meet the subsequent process requirements. In the sintering stage, the blank is placed in a high temperature environment of 900 to 1300°C. The atoms between the powder particles are fully diffused under thermal drive, tightly connected and metallurgically bonded to each other, the porosity is greatly reduced, and the density of the material is improved.

[0024] Therefore, compared with the composite wear-resistant body made by cold rolling and hot rolling, the composite wear-resistant body is made by loading the mixed powder into the mold, pressing and then sintering, which can make the internal structure of the material more uniform and stable. The cold rolling and hot rolling processes are easily disturbed by factors such as uneven rolling force of the equipment and temperature fluctuations, resulting in differences in the performance of the material in different parts; the sintering process after pressing can ensure the consistency of material performance by relying on the stable constraint of the mold and uniform heating during sintering, thereby improving the overall quality of the composite wear-resistant body, and can further improve the wear resistance, toughness and impact resistance of the knife ring; the other conditions are consistent with Example 1, so this example will not be repeated.

[0025] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A process for preparing a composite cutter ring of a shield machine, characterized in that: The following steps are included: Step 1: fully mix Fe powder with metal or non-metal and its alloy powder in a certain proportion to make a mixed powder, and perform metallurgical forming treatment on the mixed powder to make a composite wear-resistant body; Step 2: cutting the composite wear-resistant body into multiple groups of small composite wear-resistant bodies with a length of 20 mm to 80 mm, and then fixing the multiple groups of small composite wear-resistant bodies in the cavity of the casting mold; Step three: coating the outer surface of the small composite wear-resistant body with nano-reinforced particles; Step 4: pouring molten steel of the cutter ring matrix material into the cavity of the casting mold, melting the surface layer of the small section composite wear-resistant body and fusing it with the nano-reinforced particles in the matrix material, and after cooling, the small section composite wear-resistant body and the matrix material are cast into one through the reinforced particles to form a cutter ring blank; Step 5: annealing, rough machining, heat treatment and finish machining the cutter ring blank to produce a finished cutter ring.

2. A process for preparing a composite cutter ring of a shield machine according to claim 1, characterized in that: In step one, the metallurgical forming process includes drying the mixed powder and then loading it into a steel pipe, cold rolling it after sealing the ends, and then hot rolling it after heating.

3. A process for preparing a composite cutter ring of a shield machine according to claim 2, characterized in that: The components of the mixed powder are as follows by weight: 60 to 70 parts of Fe powder and 30 to 40 parts of metal or non-metal and its alloy powder; the metal or non-metal and its alloy powder are two or more of SiC, SiN, ZrO2, WC, Al2O3, B, Cr, Ni, Mo, and diamond powder.

4. A process for preparing a composite cutter ring of a shield machine according to claim 3, characterized in that: The cold rolling comprises 3 to 12 cold rolling passes, and the hot rolling after heating comprises heating to 900 to 1250° C. for hot rolling.

5. The process for preparing a composite cutter ring of a shield machine according to claim 1, characterized in that: The metallurgical forming process includes placing the mixed powder into a mold for pressing and then sintering, and the sintering temperature is 900-1300°C; the pressing includes placing the mold containing the mixed powder into a hot pressing device for hot pressing and compounding, and the temperature of the hot pressing and compounding is 100-150°C, the pressure is 0.5-1.5MPa, and the pressure is maintained for 4-7 minutes after reaching the pressure.

6. The process for preparing a composite cutter ring of a shield machine according to claim 1, characterized in that: In step 2, the small-segment composite wear-resistant body is fixed in the cavity of the casting mold by grid method or welding fixing ribs. The diameter of the small-segment composite wear-resistant body is 20mm-50mm, and the spacing between multiple groups of the small-segment composite wear-resistant body is 10mm-50mm.

7. The process for preparing a composite cutter ring of a shield machine according to claim 1, characterized in that: In step three, the nano-reinforced particles are one or more of ZrO2, WC, Al2O3, Ni powder, and high-speed steel powder, and are wrapped with phosphorus Fe powder to improve the wettability between the nano-reinforced particles and the steel liquid.

8. A process for preparing a composite cutter ring of a shield machine according to claim 7, characterized in that: The thickness of the coated nano-reinforced particles is 0.5 mm to 5 mm.

9. The process for preparing a composite cutter ring of a shield machine according to claim 1, characterized in that: In step 4, the temperature of the molten steel is 1560-1750° C., and the process is carried out under a gas protection environment and negative pressure.

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