Production process of casting part for high-voltage power equipment and casting part

Abstract

The invention discloses a casting part production process for high-voltage power equipment and a casting part, and relates to the technical field of casting machining, and the casting part production process comprises the following steps: material mixed smelting: placing steel in an electric furnace for smelting, adding a deoxidizing agent after the temperature rises to 1400-1500 DEG C, and refining for 15-20 minutes to obtain molten steel; mold setting: preparing a casting sample, putting the casting sample into a molding sand mold, and processing through a mold processing table to obtain a sand mold; casting part pouring, wherein the molten steel is subjected to centrifugal vibration to remove bubbles, and the molten steel is poured into a sand mold; and casting part cooling: taking out the formed casting part after cooling to normal temperature, carrying out surface cleaning work on the condensed electric power fitting, and polishing to obtain the casting part. Through arrangement of a deoxidizing agent, doping of different substances, pouring control and centrifugal treatment, the air hole defect generated by common casting can be effectively controlled in the casting process, and the stress of a casting part is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of casting processing, and in particular to a casting production process and a casting for high-voltage power equipment. Background Art

[0002] Casting is a relatively early metal heat processing technology mastered by humans, with a history of about 6,000 years. China entered the heyday of bronze castings between 1700 BC and 1000 BC, and the technology had reached a very high level. Casting is a method of pouring liquid metal into a casting cavity that is adapted to the shape of the part, and then cooling and solidifying it to obtain parts or rough parts. The cast material is mostly a metal that was originally solid but heated to liquid (for example: copper, iron, aluminum, tin, lead, etc.), and the material of the mold can be sand, metal or even ceramic. The method used will also be different depending on different requirements.

[0003] Traditional aluminum alloy castings have the following problems: ordinary gravity casting is prone to porosity defects (porosity > 3%), the residual stress after heat treatment reaches 80-120MPa, and the yield strength is generally lower than 280MPa. Summary of the invention

[0004] In order to solve the above technical problems, a casting production process and castings for high-voltage power equipment are provided. This technical solution solves the problems raised in the above background technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is: A casting production process for high-voltage power equipment, comprising: Mixed smelting of materials: Place the steel in an electric furnace for smelting, and when the temperature rises to 1400℃-1500℃, add a deoxidizer and refine for 15min-20min to obtain molten steel. The molten steel contains less than 0.02% sulfur, less than 0.02% phosphorus, 8.5-10.5% silicon, 0.5-0.8% manganese, 0.15-0.25% titanium, 0.08-0.12% strontium, and the remainder is steel and unavoidable impurities, where the contents are all mass fractions; Mold setting: prepare casting samples, put the casting samples into the sand mold, process them on the mold processing table to get the sand mold, bake the sand mold at a temperature of 500℃-600℃ for 10min-15min, and then cool it down to 250℃-300℃ for standby use; Casting: centrifugal vibration is performed on the molten steel to remove bubbles, and the molten steel is poured into the sand mold. The pouring temperature is 1250℃-1350℃, and the pouring time is 25s-30s. After the pouring is completed, it is kept warm for 30min-40min. During the pouring, the pressure is increased from 0.5MPa / s to 2MPa; Cooling of castings: After cooling to room temperature, take out the formed castings, clean the surface of the condensed electrical fittings to remove surface oxides and sand, and polish the castings. During cooling, the pressure rises from 0.2MPa / s to 4MPa.

[0006] Preferably, the deoxidizer is composed of ferrosilicon, ferromanganese and aluminum, and the mass ratio of ferrosilicon, ferromanganese and aluminum is 1-2:2-3:2-4.

[0007] Preferably, the sand molding mold is as follows: The parameters of the molding sand are set as follows: the air permeability of the molding sand is 80cm³ / (g·min), the wet compressive strength is 80-120kPa, the moisture content is 3.5-4.5%, the sprue: cross runner: inner runner = 1.2:1.4:1, and the gate ratio is 1.1-1.3.

[0008] Preferably, the centrifugal vibration of the molten steel to remove bubbles comprises the following steps: The centrifugal vibration speed is 60 times / min, and the vibration amplitude is one percent of the length of the molding sand.

[0009] Preferably, the step of cooling to room temperature comprises the following steps: The unpacking temperature is less than 400℃, and a step-by-step cooling method is adopted. The cooling is divided into three stages, namely initial cooling, mid-end cooling and terminal cooling. The initial cooling rate is 10-50℃ / min, and local nitrogen injection is performed on local positions, which are the load-bearing positions of the castings.

[0010] The casting is prepared according to the above-mentioned casting production process for high-voltage power equipment.

[0011] Compared with the prior art, the present invention has the following beneficial effects: By setting the deoxidizer and doping with different substances, and through the control of pouring and centrifugal treatment, the porosity defects caused by ordinary casting can be effectively controlled during the casting process, thereby improving the quality of the casting. The step-by-step cooling can effectively reduce the generation of internal stress. At the same time, the reasonable ratio of different substances can improve the strength of the casting itself, and different pressure controls are used during the pouring and cooling process to further squeeze the internal pores out of the casting as much as possible, and the synergistic effect of external pressure can reduce the stress of the casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The figure is a schematic flow chart of the casting production process for high-voltage power equipment according to the present invention. DETAILED DESCRIPTION

[0013] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations. Example 1

[0014] A casting production process for high-voltage power equipment, comprising: Mixed smelting of materials: the steel is placed in an electric furnace for smelting, and when the temperature rises to 1400°C, a deoxidizer is added and refined for 15 minutes to obtain molten steel, the molten steel contains 0.01% sulfur, 0.01% phosphorus, 8.5% silicon, 0.5% manganese, 0.15% titanium, 0.08% strontium, and the remainder is steel and unavoidable impurities, where the contents are all mass fractions; Mold setting: prepare casting samples, put the casting samples into the sand mold, process them on the mold processing table to get the sand mold, bake the sand mold at 500℃ for 10min, and then cool it down to 250℃ for standby use; Casting: centrifugal vibration is performed on the molten steel to remove bubbles, and the molten steel is poured into the sand mold at a pouring temperature of 1250°C and a pouring time of 25 seconds. After the pouring is completed, the temperature is kept at room temperature for 30 minutes. During the pouring, the pressure is increased from 0.5MPa / s to 2MPa. Cooling of castings: After cooling to room temperature, take out the formed castings, clean the surface of the condensed electrical fittings to remove surface oxides and sand, and polish the castings. During cooling, the pressure rises from 0.2MPa / s to 4MPa.

[0015] The deoxidizer is composed of ferrosilicon, ferromanganese and aluminum, and the mass ratio of ferrosilicon, ferromanganese and aluminum is 1:2:2.

[0016] The details of the sand mold are as follows: The parameters of the molding sand are set as follows: the air permeability of the molding sand is 80 cm³ / (g·min), the wet compressive strength is 80 kPa, the moisture content is 3.5%, the sprue: cross runner: inner runner = 1.2:1.4:1, and the gate ratio is 1.1.

[0017] Centrifugal vibration of molten steel to remove bubbles includes the following steps: The centrifugal vibration speed is 60 times / min, and the vibration amplitude is one percent of the length of the molding sand.

[0018] The cooling to room temperature comprises the following steps: The unpacking temperature is 300°C, and a step-by-step cooling method is used. The cooling is divided into three stages, namely initial cooling, mid-end cooling and terminal cooling. The initial cooling rate is 10°C / min, and local nitrogen injection is performed at local locations, which are the load-bearing positions of the castings.

[0019] The casting is prepared according to the above-mentioned casting production process for high-voltage power equipment. Example 2

[0020] A casting production process for high-voltage power equipment, comprising: Mixed smelting of materials: the steel is placed in an electric furnace for smelting, and when the temperature rises to 1460°C, a deoxidizer is added and refined for 16 minutes to obtain molten steel, the molten steel contains 0.01% sulfur, 0.01% phosphorus, 8.9% silicon, 0.56% manganese, 0.17% titanium, 0.085% strontium, and the remainder is steel and unavoidable impurities, where the contents are all mass fractions; Mold setting: prepare casting samples, put the casting samples into the sand mold, process them on the mold processing table to get the sand mold, bake the sand mold at a temperature of 520°C for 11 minutes, and then cool it down to 260°C for use; Casting: centrifugal vibration is performed on the molten steel to remove bubbles, and the molten steel is poured into the sand mold. The pouring temperature is 1270℃ and the pouring time is 26s. After the pouring is completed, it is kept warm for 32min. During the pouring, the pressure is increased from 0.5MPa / s to 2MPa; Cooling of castings: After cooling to room temperature, take out the formed castings, clean the surface of the condensed electrical fittings to remove surface oxides and sand, and polish the castings. During cooling, the pressure rises from 0.2MPa / s to 4MPa.

[0021] The deoxidizer is composed of ferrosilicon, ferromanganese and aluminum, and the mass ratio of ferrosilicon, ferromanganese and aluminum is 1.2:2.2:2.4.

[0022] The details of the sand mold are as follows: The parameters of the molding sand are set as follows: the air permeability of the molding sand is 80 cm³ / (g·min), the green compressive strength is 88 kPa, the moisture content is 3.7%, the sprue: cross runner: inner runner = 1.2:1.4:1, and the gate ratio is 1.14.

[0023] Centrifugal vibration of molten steel to remove bubbles includes the following steps: The centrifugal vibration speed is 60 times / min, and the vibration amplitude is one percent of the length of the molding sand.

[0024] The cooling to room temperature comprises the following steps: The unpacking temperature is 300℃, and the step-by-step cooling is adopted. The cooling is divided into three stages, namely initial cooling, mid-end cooling and terminal cooling. The initial cooling rate is 18℃ / min, and local nitrogen injection is performed on local positions, which are the load-bearing positions of the castings.

[0025] The casting is prepared according to the above-mentioned casting production process for high-voltage power equipment. Example 3

[0026] A casting production process for high-voltage power equipment, comprising: Mixed smelting of materials: the steel is placed in an electric furnace for smelting, and when the temperature rises to 1440°C, a deoxidizer is added and refined for 17 minutes to obtain molten steel, the molten steel contains 0.01% sulfur, 0.01% phosphorus, 9.3% silicon, 0.62% manganese, 0.19% titanium, 0.096% strontium, and the remainder is steel and unavoidable impurities, where the contents are all mass fractions; Mold setting: prepare casting samples, put the casting samples into the sand mold, process them on the mold processing table to get the sand mold, bake the sand mold at 540℃ for 12min, and then cool it to 270℃ for standby use; Casting: centrifugal vibration is performed on the molten steel to remove bubbles, and the molten steel is poured into the sand mold. The pouring temperature is 1290℃ and the pouring time is 27s. After the pouring is completed, it is kept warm for 34min. During the pouring, the pressure is increased from 0.5MPa / s to 2MPa; Cooling of castings: After cooling to room temperature, take out the formed castings, clean the surface of the condensed electrical fittings to remove surface oxides and sand, and polish the castings. During cooling, the pressure rises from 0.2MPa / s to 4MPa.

[0027] The deoxidizer is composed of ferrosilicon, ferromanganese and aluminum, and the mass ratio of ferrosilicon, ferromanganese and aluminum is 1.4:2.4:2.8.

[0028] The details of the sand mold are as follows: The parameters of the molding sand are set as follows: the air permeability of the molding sand is 80 cm³ / (g·min), the green compressive strength is 96 kPa, the moisture content is 3.9%, the sprue: cross runner: inner runner = 1.2:1.4:1, and the gate ratio is 1.18.

[0029] Centrifugal vibration of molten steel to remove bubbles includes the following steps: The centrifugal vibration speed is 60 times / min, and the vibration amplitude is one percent of the length of the molding sand.

[0030] The cooling to room temperature comprises the following steps: The unpacking temperature is 300℃, and the step-by-step cooling is adopted. The cooling is divided into three stages, namely initial cooling, mid-end cooling and terminal cooling. The initial cooling rate is 30℃ / min, and local nitrogen injection is performed on local positions, which are the load-bearing positions of the castings.

[0031] The casting is prepared according to the above-mentioned casting production process for high-voltage power equipment. Example 4

[0032] A casting production process for high-voltage power equipment, comprising: Mixed smelting of materials: the steel is placed in an electric furnace for smelting, and when the temperature rises to 1460°C, a deoxidizer is added and refined for 18 minutes to obtain molten steel, the molten steel contains 0.01% sulfur, 0.01% phosphorus, 9.7% silicon, 0.68% manganese, 0.21% titanium, 0.104% strontium, and the remainder is steel and unavoidable impurities, where the contents are all mass fractions; Mold setting: prepare casting samples, put the casting samples into the sand mold, process them on the mold processing table to get the sand mold, bake the sand mold at a temperature of 560°C for 13 minutes, and then cool it down to 280°C for use; Casting: centrifugal vibration is performed on the molten steel to remove bubbles, and the molten steel is poured into the sand mold. The pouring temperature is 1310℃ and the pouring time is 28s. After the pouring is completed, it is kept warm for 36 minutes. During the pouring, the pressure is increased from 0.5MPa / s to 2MPa; Cooling of castings: After cooling to room temperature, take out the formed castings, clean the surface of the condensed electrical fittings to remove surface oxides and sand, and polish the castings. During cooling, the pressure rises from 0.2MPa / s to 4MPa.

[0033] The deoxidizer is composed of ferrosilicon, ferromanganese and aluminum, and the mass ratio of ferrosilicon, ferromanganese and aluminum is 1.6:2.6:3.2.

[0034] The details of the sand mold are as follows: The parameters of the molding sand are set as follows: the air permeability of the molding sand is 80 cm³ / (g·min), the green compressive strength is 104 kPa, the moisture content is 4.1%, the sprue: cross runner: inner runner = 1.2:1.4:1, and the gate ratio is 1.22.

[0035] Centrifugal vibration of molten steel to remove bubbles includes the following steps: The centrifugal vibration speed is 60 times / min, and the vibration amplitude is one percent of the length of the molding sand.

[0036] The cooling to room temperature comprises the following steps: The unpacking temperature is 300℃, and the step-by-step cooling is adopted. The cooling is divided into three stages, namely initial cooling, mid-end cooling and terminal cooling. The initial cooling rate is 40℃ / min, and local nitrogen injection is performed on local positions, which are the load-bearing positions of the castings.

[0037] The casting is prepared according to the above-mentioned casting production process for high-voltage power equipment. Example 5

[0038] A casting production process for high-voltage power equipment, comprising: Mixed smelting of materials: the steel is placed in an electric furnace for smelting, and when the temperature rises to 1500°C, a deoxidizer is added and refined for 20 minutes to obtain molten steel, the molten steel contains 0.01% sulfur, 0.01% phosphorus, 10.5% silicon, 0.8% manganese, 0.25% titanium, 0.12% strontium, and the remainder is steel and unavoidable impurities, where the contents are all mass fractions; Mold setting: prepare casting samples, put the casting samples into the sand mold, process them on the mold processing table to get the sand mold, bake the sand mold at 600℃ for 15min, and then cool it to 300℃ for standby use; Casting: centrifugal vibration is performed on the molten steel to remove bubbles, and the molten steel is poured into the sand mold. The pouring temperature is 1350℃ and the pouring time is 30s. After the pouring is completed, it is kept warm for 40 minutes. During the pouring, the pressure is increased from 0.5MPa / s to 2MPa; Cooling of castings: After cooling to room temperature, take out the formed castings, clean the surface of the condensed electrical fittings to remove surface oxides and sand, and polish the castings. During cooling, the pressure rises from 0.2MPa / s to 4MPa.

[0039] The deoxidizer is composed of ferrosilicon, ferromanganese and aluminum, and the mass ratio of ferrosilicon, ferromanganese and aluminum is 2:3:4.

[0040] The details of the sand mold are as follows: The parameters of the molding sand are set as follows: the air permeability of the molding sand is 80 cm³ / (g·min), the wet compressive strength is 120 kPa, the moisture content is 4.5%, the sprue: cross runner: inner runner = 1.2:1.4:1, and the gate ratio is 1.3.

[0041] Centrifugal vibration of molten steel to remove bubbles includes the following steps: The centrifugal vibration speed is 60 times / min, and the vibration amplitude is one percent of the length of the molding sand.

[0042] The cooling to room temperature comprises the following steps: The unpacking temperature is 300℃, and the step-by-step cooling is adopted. The cooling is divided into three stages, namely initial cooling, mid-end cooling and terminal cooling. The initial cooling rate is 50℃ / min, and local nitrogen injection is performed on local positions, which are the load-bearing positions of the castings.

[0043] The casting is prepared according to the above-mentioned casting production process for high-voltage power equipment.

[0044] Porosity test The castings are sampled, mounted, ground and polished (to Ra≤0.05μm), and images are acquired under a microscope (observation magnification is 100-500 times); Use image analysis software to calculate the pore area percentage; Porosity (%) = (total pore area / field of view area) × 100. The porosity of at least 5 different fields of view was averaged to obtain the final porosity.

[0045] Yield strength test Clamp the specimen (coaxiality deviation ≤ 5%) and preload it to 10% of the estimated yield strength; Loading in strain rate controlled mode: Elastic stage: 0.00025 / s Plastic stage: 0.0067 / s The force-displacement curve was recorded until fracture, and the yield strength was obtained; Key parameter control during the test: Temperature: 23±5℃ (actual temperature must be recorded); Humidity: 30-70%RH; Clamping pressure: not more than 20MPa.

[0046] Fatigue life test The test type is high-frequency fatigue test, the load form is electromagnetic resonance, the frequency range is 70-150Hz, and the equipment is Instron 1603; Key parameter settings: Stress ratio (R=σmin / σmax): Symmetric cycle: R=-1; Pulsation cycle: R=0; Load waveform: sine wave (most commonly used), triangle wave, square wave; Environmental Control: Temperature: 23±2℃; Humidity: 50±10%RH; Corrosion fatigue requires a medium circulation system; Pre-test stage: Static tensile testing determines material strength (used to set stress levels); Step test method with at least 3 stress levels; Formal test: The group method was used (≥8 valid samples per group); Termination conditions: The specimen breaks; Reach the specified number of cycles (such as 10 for cast iron parts)7 Second-rate); The crack grows to a critical size (COD monitoring), and the test frequency at this time is recorded.

[0047] Internal stress testing Paste strain rosette (0° / 45° / 90° three-way); Use a 2mm diameter drill bit to drill holes layer by layer (depth ≈ 1.2 times the hole diameter); Record the amount of strain relief.

[0048]

[0049]

[0050] In summary, the advantages of the present invention are: through the setting of the deoxidizer and the doping of different substances, and through the control of pouring and centrifugal treatment, the pore defects caused by ordinary casting can be effectively controlled during the casting process, thereby improving the quality of the casting, and the step-by-step cooling can effectively reduce the generation of internal stress. At the same time, the reasonable ratio of different substances can improve the strength of the casting itself, and different pressure controls are used during the pouring and cooling process to further squeeze the internal pores out of the casting as much as possible, and the synergistic effect of external pressure can reduce the stress of the casting.

[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A casting production process for high-voltage power equipment, characterized in that: include: Mixed smelting of materials: Place the steel in an electric furnace for smelting, and when the temperature rises to 1400℃-1500℃, add a deoxidizer and refine for 15min-20min to obtain molten steel. The molten steel contains less than 0.02% sulfur, less than 0.02% phosphorus, 8.5-10.5% silicon, 0.5-0.8% manganese, 0.15-0.25% titanium, 0.08-0.12% strontium, and the remainder is steel and unavoidable impurities, where the contents are all mass fractions; Mold setting: prepare casting samples, put the casting samples into the sand mold, process them on the mold processing table to get the sand mold, bake the sand mold at a temperature of 500℃-600℃ for 10min-15min, and then cool it down to 250℃-300℃ for standby use; Casting: centrifugal vibration is performed on the molten steel to remove bubbles, and the molten steel is poured into the sand mold. The pouring temperature is 1250℃-1350℃, and the pouring time is 25s-30s. After the pouring is completed, it is kept warm for 30min-40min. During the pouring, the pressure is increased from 0.5MPa / s to 2MPa; Cooling of castings: After cooling to room temperature, take out the formed castings, clean the surface of the condensed electrical fittings to remove surface oxides and sand, and polish the castings. During cooling, the pressure rises from 0.2MPa / s to 4MPa.

2. A casting production process for high-voltage power equipment according to claim 1, characterized in that: The deoxidizer is composed of ferrosilicon, ferromanganese and aluminum, and the mass ratio of ferrosilicon, ferromanganese and aluminum is 1-2:2-3:2-4.

3. A casting production process for high-voltage power equipment according to claim 2, characterized in that: The sand mold is specifically as follows: The parameters of the molding sand are set as follows: the air permeability of the molding sand is 80cm³ / (g·min), the wet compressive strength is 80-120kPa, the moisture content is 3.5-4.5%, the sprue: cross runner: inner runner = 1.2:1.4:1, and the gate ratio is 1.1-1.

3.

4. A casting production process for high-voltage power equipment according to claim 3, characterized in that: The centrifugal vibration of molten steel to remove bubbles comprises the following steps: The centrifugal vibration speed is 60 times / min, and the vibration amplitude is one percent of the length of the molding sand.

5. A casting production process for high-voltage power equipment according to claim 4, characterized in that: The cooling to room temperature comprises the following steps: The unpacking temperature is less than 400℃, and a step-by-step cooling method is adopted. The cooling is divided into three stages, namely initial cooling, mid-end cooling and terminal cooling. The initial cooling rate is 10-50℃ / min, and local nitrogen injection is performed on local positions, which are the load-bearing positions of the castings.

6. A casting produced according to the casting production process for high-voltage power equipment according to any one of claims 1 to 5.

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