Preparation method of hob cutter ring of shield tunneling machine

Abstract

The invention relates to the technical field of shield tunneling machine cutter ring production, and discloses a shield tunneling machine hob cutter ring preparation method, which comprises: 1, loading steel scrap and pig iron into an electric furnace, heating, gradually heating to a melting temperature of 1500-1600 DEG C, wherein the steel scrap accounts for 70-80%, the pig iron accounts for 10-20%, and the liquid accounts for 10-20%; 2, after the molten steel is melted, alloy elements are added, and after addition, the molten steel is stirred through a steel rake; 3, after the molten steel and alloy elements are mixed, deoxidation, desulfurization and degassing are carried out; 4, casting the smelted molten steel into a blank with a proper size, and putting the blank into a heating furnace; and fifthly, the forged forging stock is naturally cooled to the room temperature in air, tempering is conducted after quenching, and therefore the shield tunneling machine hob cutter ring is prepared. Alloy elements such as ferrochrome, ferromolybdenum and ferrovanadium are added after molten steel is melted, and the alloy elements are stirred by using a steel rake to be uniformly distributed, so that the technical effects of optimizing the material performance of the cutter ring and improving the hardness, wear resistance and the like are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of shield machine cutter ring production, in particular to a method for preparing a shield machine roller cutter ring. Background Art

[0002] At present, in tunnel excavation projects, shield machines are widely used as an important construction equipment in urban subways, railway tunnels and other projects. Among them, the roller cutter, as one of the key components of the shield machine, undertakes the main task of breaking rocks. However, since the roller cutter is subjected to great impact loads and wear during work, its life is short. Frequent replacement not only increases construction costs, but also affects construction progress. Therefore, the development of highly wear-resistant and long-life roller cutter rings has become an important research topic.

[0003] Traditional hob cutter rings are mostly made of cast steel or forged steel, which are heat treated to improve hardness and strength. Although this material has good mechanical properties, it is still prone to cracking and peeling under long-term high-intensity working conditions, resulting in cutter ring failure.

[0004] In recent years, some researchers have tried to use composite materials to improve the performance of hob cutter rings, such as tungsten carbide-based composite materials. These materials have high hardness and corrosion resistance, but their high cost and difficulty in processing limit their widespread application.

[0005] In addition, some research focuses on surface modification and coating technology, such as forming a protective film on the surface of the cutter ring through laser cladding, electroplating, etc. to improve its wear resistance. These methods can extend the service life of the cutter ring to a certain extent, but there is still the problem of easy detachment of the coating.

[0006] Although the existing hob cutter ring preparation technology has made certain progress, the following problems still exist: first, it is difficult to balance the hardness and toughness of the material itself, which makes the cutter ring easy to be damaged during actual use; second, the cost of composite materials and surface modification technology is high, which is not economical and practical; third, the effect of certain improvement measures is limited and cannot significantly improve the overall performance of the cutter ring. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a method for preparing a shield machine cutter ring, which solves the problems of low hardness and poor wear resistance.

[0008] To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for preparing a shield machine cutter ring, comprising the following steps: Step 1: Load scrap steel and pig iron into the electric furnace and start heating, gradually raising the temperature to the melting temperature of 1500℃~1600℃, with scrap steel accounting for 70%~80% and pig iron accounting for 10%~20%. Observe the situation in the furnace to ensure that the scrap steel and pig iron are completely melted to form a uniform molten steel; Step 2: When the molten steel is melted, alloy elements are added, and after adding, the molten steel is stirred with a steel rake to make the alloy elements evenly distributed, and then rare earth element alloy additives are added; Step 3: After the molten steel and alloy elements are mixed, deoxidation, desulfurization and degassing are carried out to obtain smelted molten steel; Step 4: Cast the molten steel into a billet of suitable size, put the billet into a heating furnace, slowly heat it to 1150℃~1250℃ and then forge it; Step 5: The forged forging blank is naturally cooled to room temperature in the air, and then the forging blank is quenched and tempered after quenching, thereby completing the preparation of the shield machine cutter ring.

[0009] Preferably, the alloying elements in step 2 are: ferrochrome, ferromolybdenum and ferrovanadium, wherein the amount of ferrochrome added is 2% to 5% of the entire molten steel, the amount of ferromolybdenum added is 0.5% to 2% of the entire molten steel, and the amount of ferrovanadium added is 0.1% to 0.5% of the entire molten steel.

[0010] Preferably, the alloy additive in step 2 is slowly added to the molten steel in an amount of 0.01% to 0.1% by weight of the total raw materials. After addition, argon is blown into the molten steel for stirring, the flow rate is controlled at 10 to 20 L / min, the stirring time is 5 to 15 minutes, so that the rare earth elements are evenly dispersed in the molten steel, and then left to stand for 10 to 20 minutes.

[0011] Preferably, the deoxidation work in step three is: in the later stage of smelting, adding 0.05% to 0.15% of the total volume of deoxidizer to the molten steel.

[0012] Preferably, the desulfurization work in step three is: adding 0.2% to 0.5% of the total mass of lime and 0.02% to 0.1% of fluorite to the molten steel, and after adding, stirring the molten steel, and maintaining the stirring speed within a certain range to allow the desulfurizer to fully contact the molten steel, and the stirring time is 10 to 20 minutes.

[0013] Preferably, the degassing work in step 3 is: move the ladle to the vacuum degassing equipment, turn on the vacuum pump, and reduce the vacuum degree to 100-500 Pa. During the degassing process, electromagnetic stirring is performed, the argon flow rate is controlled at 5-15 L / min, and the degassing is continued for 15-30 minutes.

[0014] Preferably, in the step 4, when the blank reaches the forging temperature, it is transferred to the forging equipment, and firstly subjected to upsetting operation, and the upsetting ratio is controlled between 2 and 3. During the operation, the initial forging temperature is not lower than 1100°C. After upsetting, the drawing operation is then carried out, and the drawing ratio is controlled between 4 and 6, and the final forging temperature is also ensured to be not lower than 850°C.

[0015] Preferably, after the forging in step 4 is completed, the cutter ring forging blank is placed in a slow cooling pit for slow cooling. The slow cooling pit can be filled with insulation material, and the cooling rate is controlled at 20°C / hour to reduce the temperature of the cutter ring forging blank to 300°C~400°C.

[0016] Preferably, the quenching work in step five is: putting the cooled cutter ring forging blank into a heating furnace, heating it to 820° C. to 860° C., the heating time is 1.5 to 2 minutes per millimeter thickness according to the size of the cutter ring, and keeping it warm.

[0017] Preferably, after the insulation is completed, the knife ring is quickly placed in quenching oil for quenching, the quenching oil temperature is maintained at 40°C~60°C, the quenched knife ring is placed in a tempering furnace, heated to 550°C~650°C, and kept warm for 2 to 3 hours.

[0018] The present invention provides a method for preparing a shield machine cutter ring, which has the following beneficial effects: 1. The present invention achieves the technical effects of optimizing the performance of the knife ring material, improving the hardness and wear resistance, etc. by adding alloy elements such as ferrochromium, ferromolybdenum and ferrovanadium after the molten steel is melted, stirring with a steel rake to make it evenly distributed, and then adding rare earth element alloy additives.

[0019] 2. The present invention has the technical solution of performing deoxidation, desulfurization and degassing respectively after the molten steel and the alloy elements are mixed, thereby achieving the technical effect of effectively removing impurities in the molten steel, improving the purity of the molten steel, and further improving the quality of the knife ring.

[0020] 3. The forged forging blank of the present invention is first naturally cooled to room temperature in the air, and then quenched and tempered. The technical scheme of accurately setting parameters such as quenching and tempering temperature and time achieves the technical effect of further optimizing the comprehensive properties such as hardness and toughness of the cutter ring and improving the service life of the cutter ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of the present invention; DETAILED DESCRIPTION The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example: The embodiment of the present invention provides a method for preparing a shield machine cutter ring, comprising the following steps: Step 1: Load scrap steel and pig iron into the electric furnace and start heating, gradually raising the temperature to the melting temperature of 1500℃~1600℃, with scrap steel accounting for 70%~80% and pig iron accounting for 10%~20%. Observe the situation in the furnace to ensure that the scrap steel and pig iron are completely melted to form a uniform molten steel; Step 2: When the molten steel is melted, alloy elements are added, and after adding, the molten steel is stirred with a steel rake to make the alloy elements evenly distributed, and then rare earth element alloy additives are added; Step 3: After the molten steel and alloy elements are mixed, deoxidation, desulfurization and degassing are carried out to obtain smelted molten steel; Step 4: Cast the molten steel into a billet of suitable size, put the billet into a heating furnace, slowly heat it to 1150℃~1250℃ and then forge it; Step 5: The forged forging blank is naturally cooled to room temperature in the air, and then the forging blank is quenched and tempered after quenching, thereby completing the preparation of the shield machine cutter ring.

[0023] Specifically, the present invention loads scrap steel and pig iron into an electric furnace in a specific ratio for heating and melting. Scrap steel accounts for 70% to 80% of the total raw materials, and pig iron accounts for 10% to 20%. The temperature is gradually raised to 1500°C to 1600°C, and the furnace is closely observed to ensure that both are completely melted to form uniform molten steel, effectively utilizing the low-cost resource of scrap steel and significantly reducing production costs; at the same time, precise raw material ratio and melting temperature control ensure uniform composition of molten steel, providing stable and high-quality basic materials for subsequent processes.

[0024] The alloying elements in step 2 are: ferrochrome, ferromolybdenum and ferrovanadium, wherein the ferrochrome addition amount is 2% to 5% of the entire molten steel, the ferromolybdenum addition amount is 0.5% to 2% of the entire molten steel, and the ferrovanadium addition amount is 0.1% to 0.5% of the entire molten steel.

[0025] The alloy additive in step 2 is slowly added into the molten steel, and the addition amount is 0.01% to 0.1% of the total raw material weight. After addition, argon gas is blown into the molten steel for stirring, and the flow rate is controlled at 10 to 20 L / min. The stirring time is 5 to 15 minutes, so that the rare earth elements are evenly dispersed in the molten steel, and then it is allowed to stand for 10 to 20 minutes.

[0026] Specifically, after the liquid is melted, add a specific proportion of 2% to 5% ferrochromium, 0.5% to 2% ferromolybdenum, and 0.1% to 0.5% ferrovanadium as alloying elements, and stir with a steel rake, then add rare earth element alloy additives, control the addition amount to 0.01% to 0.1% of the total raw material weight, blow argon after adding, stir at a flow rate of 10 to 20 L / min, stir for 5 to 15 minutes and let stand for 10 to 20 minutes. The precise ratio of alloying elements can comprehensively improve the comprehensive properties of the knife ring, such as hardness, wear resistance, and toughness; for example, ferrochromium enhances hardness and corrosion resistance, ferromolybdenum improves strength and toughness, and ferrovanadium refines grains to improve comprehensive performance; rare earth elements are evenly dispersed to further optimize the performance of molten steel The deoxidation work in step three is: in the later stage of smelting, 0.05% to 0.15% of the total volume of deoxidizer is added to the molten steel.

[0027] The desulfurization work in step three is as follows: add 0.2% to 0.5% of the total mass of lime and 0.02% to 0.1% of fluorite to the molten steel. After the addition, stir the molten steel, and keep the stirring speed within a certain range to make the desulfurizer fully contact with the molten steel. The stirring time is 10 to 20 minutes.

[0028] The degassing work in step 3 is as follows: move the ladle to the vacuum degassing equipment, turn on the vacuum pump, and reduce the vacuum degree to 100-500 Pa. During the degassing process, electromagnetic stirring is performed, the argon flow rate is controlled at 5-15 L / min, and the degassing is continued for 15-30 minutes.

[0029] Specifically, in the later stage of smelting, 0.05% to 0.15% of the total volume of deoxidizer is added to the molten steel for deoxidation, which effectively removes oxygen from the molten steel, reduces oxide inclusions, and significantly improves the purity of the molten steel, thereby improving the quality and performance stability of the cutter ring and reducing the risk of internal defects caused by oxides; desulfurization can efficiently remove sulfur from the molten steel and reduce the sulfur content. Reduce the adverse effects of sulfur on the hot working properties of steel, improve the thermal cracking resistance and toughness of the cutter ring, and make it more reliable in high-temperature working environments; degassing can fully remove gas from the molten steel, reduce internal defects such as pores, improve the internal quality and density of the cutter ring, and enhance the performance of the cutter ring under high pressure and high stress conditions.

[0030] In step 4, when the billet reaches the forging temperature, it is transferred to the forging equipment and firstly subjected to upsetting operation with the upsetting ratio controlled between 2 and 3. During the operation, the initial forging temperature is not lower than 1100°C. After upsetting, the drawing operation is then carried out with the drawing ratio controlled between 4 and 6. The final forging temperature is also ensured to be not lower than 850°C.

[0031] Step 4: After forging is completed, the knife ring forging blank is placed in a slow cooling pit for slow cooling. The slow cooling pit can be filled with insulation material, and the cooling rate is controlled at 20°C / hour to reduce the temperature of the knife ring forging blank to 300°C~400°C.

[0032] Specifically, after the billet is heated to 1150℃~1250℃, it is first subjected to upsetting operation (upsetting ratio 2~3, initial forging temperature not less than 1100℃), and then subjected to drawing operation (drawing ratio 4~6, final forging temperature not less than 850℃), so that the grains inside the cutter ring are refined and evenly distributed, the internal organizational structure is significantly improved, and the strength, toughness and other mechanical properties of the cutter ring are improved, so that it can better adapt to the complex working conditions of the shield machine; the forged forging billet is first naturally cooled to room temperature in the air, and then placed in a slow cooling pit, filled with thermal insulation material, and the cooling rate is controlled at 20℃ / hour to reduce the temperature to 300℃~400℃. The method of natural cooling first and then slow cooling is adopted, and the slow cooling rate is accurately controlled to effectively avoid thermal stress concentration caused by too fast cooling, prevent cracks, ensure the quality stability of the cutter ring forging billet, and improve the product qualification rate.

[0033] The quenching work in step five is as follows: the cooled knife ring forging blank is placed in a heating furnace, heated to 820°C~860°C, the heating time is 1.5~2 minutes per millimeter thickness according to the size of the knife ring, and the temperature is kept warm.

[0034] After the insulation is completed, the knife ring is quickly placed in the quenching oil for quenching. The quenching oil temperature is maintained at 40℃~60℃. The quenched knife ring is placed in the tempering furnace, heated to 550℃~650℃, and kept warm for 2 to 3 hours.

[0035] Specifically, the cooled cutter ring forging blank is heated to 820℃~860℃, heated for 1.5~2 minutes per millimeter of thickness and kept warm, then quickly placed in quenching oil at 40℃~60℃ for quenching, and then placed in a tempering furnace and heated to 550℃~650℃ for 2~3 hours. The heating time is accurately calculated according to the size of the cutter ring to achieve an ideal balance of hardness and toughness for the cutter ring. The quenching and tempering processes work together to make the cutter ring both resistant to wear and brittle fracture, greatly improving the service life and working reliability of the cutter ring.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a shield machine cutter ring, characterized in that: The following steps are involved: Step 1: Load scrap steel and pig iron into the electric furnace and start heating, gradually raising the temperature to the melting temperature of 1500℃~1600℃, with scrap steel accounting for 70%~80% and pig iron accounting for 10%~20%. Observe the situation in the furnace to ensure that the scrap steel and pig iron are completely melted to form a uniform molten steel; Step 2: When the molten steel is melted, alloy elements are added, and after adding, the molten steel is stirred with a steel rake to make the alloy elements evenly distributed, and then rare earth element alloy additives are added; Step 3: After the molten steel and alloy elements are mixed, deoxidation, desulfurization and degassing are carried out to obtain smelted molten steel; Step 4: Cast the molten steel into a billet of suitable size, put the billet into a heating furnace, slowly heat it to 1150℃~1250℃ and then forge it; Step 5: The forged forging blank is naturally cooled to room temperature in the air, and then the forging blank is quenched and tempered after quenching, thereby completing the preparation of the shield machine cutter ring.

2. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: The alloying elements in step 2 are: ferrochrome, ferromolybdenum and ferrovanadium, wherein the amount of ferrochrome added is 2% to 5% of the entire molten steel, the amount of ferromolybdenum added is 0.5% to 2% of the entire molten steel, and the amount of ferrovanadium added is 0.1% to 0.5% of the entire molten steel.

3. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: The alloy additive in step 2 is slowly added into the molten steel, and the addition amount is 0.01% to 0.1% of the total raw material weight. After the addition, argon gas is blown into the molten steel for stirring, and the flow rate is controlled at 10 to 20 L / min. The stirring time is 5 to 15 minutes, so that the rare earth elements are evenly dispersed in the molten steel, and then it is allowed to stand for 10 to 20 minutes.

4. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: The deoxidation work in step three is as follows: in the later stage of smelting, 0.05% to 0.15% of the total volume of deoxidizer is added to the molten steel.

5. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: The desulfurization work in step three is as follows: adding 0.2% to 0.5% of lime and 0.02% to 0.1% of fluorite by total weight to the molten steel, and after adding, stirring the molten steel, and maintaining the stirring speed within a certain range so that the desulfurizer is in full contact with the molten steel, and the stirring time is 10 to 20 minutes.

6. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: The degassing work in step 3 is as follows: move the ladle to the vacuum degassing equipment, turn on the vacuum pump, and reduce the vacuum degree to 100-500 Pa. During the degassing process, electromagnetic stirring is performed, the argon flow rate is controlled at 5-15 L / min, and the degassing is continued for 15-30 minutes.

7. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: In the step 4, when the blank reaches the forging temperature, it is transferred to the forging equipment, and firstly subjected to upsetting operation, and the upsetting ratio is controlled between 2 and 3. During the operation, the initial forging temperature is not lower than 1100°C. After upsetting, the drawing operation is then carried out, and the drawing ratio is controlled between 4 and 6, and the final forging temperature is also ensured to be not lower than 850°C.

8. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: After the forging in step 4 is completed, the cutter ring forging blank is placed in a slow cooling pit for slow cooling. The slow cooling pit can be filled with heat insulation material, and the cooling rate is controlled at 20°C / hour to reduce the temperature of the cutter ring forging blank to 300°C~400°C.

9. The method for preparing a shield machine cutter ring according to claim 1, characterized in that: The quenching work in step five is as follows: putting the cooled cutter ring forging blank into a heating furnace, heating it to 820° C. to 860° C., heating time is 1.5 to 2 minutes per millimeter thickness according to the size of the cutter ring, and keeping it warm.

10. The method for preparing a shield machine cutter ring according to claim 9, characterized in that: After the insulation is completed, the knife ring is quickly placed in quenching oil for quenching, the quenching oil temperature is maintained at 40°C~60°C, the quenched knife ring is placed in a tempering furnace, heated to 550°C~650°C, and kept warm for 2~3 hours.

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