Casting method for producing brake disc by adopting green sand multi-layer stacking box process

Abstract

The invention belongs to the technical field of automobile part casting, and particularly relates to a casting method for producing a brake disc through a green sand multi-layer stacking box process. Molten iron obtained through inoculation is poured into a casting mold cavity jointly formed by a core set and a sand mold made of green sand in a layered mode, stream secondary inoculation and heat preservation are carried out in the pouring process to obtain a blank casting, heat treatment is carried out, then the constant temperature is kept, furnace cooling and discharging are carried out, air cooling is carried out after discharging is carried out, and the casting is obtained. Performing numerical control processing on the blank casting to obtain a finished cast iron brake disc; compared with a single-layer brake disc, the brake disc produced by adopting the green sand multi-layer stacking box process has the advantages that the manufacturing and production efficiency is greatly improved, and the cost is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile parts casting, and in particular relates to a casting method for producing brake discs by adopting a green sand multi-layer box stacking process. Background Art

[0002] At present, the size of the sand box for producing brake discs is 1200mm long, 800mm wide, 400mm high for the upper box, 400mm high for the lower box, and the height of the brake disc casting is only 60mm. Each sand mold can only cast 3 pieces in single-layer production, each piece weighs 16Kg. Each shift produces 400 boxes, and only produces a maximum of 1200 castings, which is extremely low in production efficiency. The weight of molten iron per mold is 90Kg, the sand-iron ratio is low, and the weight of three castings per mold is only 48Kg. The process yield rate is less than 60%, and the cost is high. Summary of the invention

[0003] In order to overcome the above problems, the present invention provides a casting method for producing brake discs using a green sand multi-layer stacking process; compared with single-layer brake discs, the manufacturing efficiency is greatly improved and the cost is greatly reduced; during the pouring process, molten iron is poured layer by layer, and the molten iron fills the mold smoothly with a multi-layer sand core combination to ensure the size progress of the casting; holes are designed in the middle of all sand cores to form air chambers to ensure that the casting has no pores and is of excellent quality.

[0004] A casting method for producing a brake disc using a green sand multi-layer stacking process, comprising the following contents:

[0005] Step 1, smelting: the raw materials are ferromanganese, ferromolybdenum, electrolytic copper, high carbon chromium, electrolytic nickel, low sulfur recarburizer, recycled materials and car body scrap steel;

[0006] The above raw materials are added to the medium frequency induction furnace in the order of low sulfur carburizer, ferrosilicon, ferromanganese, ferromolybdenum, electrolytic copper, high carbon chromium, electrolytic nickel and scrap steel of the vehicle body for smelting, and the smelting power is gradually increased until the raw materials are completely melted into molten iron, and then the recycled materials and the remaining scrap steel of the vehicle body are added to the medium frequency induction furnace, and then the temperature is kept until all the materials are melted; so that the molten iron contains the following components, and the content of each component reaches the following standards, all calculated by weight percentage:

[0007] Carbon 3.72%, silicon 1.70%, manganese 0.60%, chromium 0.15%, copper 0.55%, molybdenum 0.1%, nickel 0.19%, the balance is iron and unavoidable impurities;

[0008] Step 2, inoculation treatment: After all the charge is melted, the temperature is maintained at 1480°C to prepare for taking out of the furnace. When taking out of the furnace, add a silicon-barium inoculant of 0.4% of the weight of the molten iron into the casting ladle, and then pour the molten iron into the casting ladle, and take out of the furnace and inoculate at one time;

[0009] Step 3: pouring and secondary inoculation: pour the molten iron obtained from the inoculation in step 2 into the brake disc casting cavity formed by the sand mold made of the core group and the green sand in layers, with a pouring temperature of 1330°C.

[0010] -1390℃, secondary inoculation is carried out during the pouring process, the inoculant is ferrosilicon inoculant, and the dosage is 0.3-0.4% of the weight of the molten iron before pouring and inoculation;

[0011] Step 4, insulation: After pouring and secondary inoculation, the obtained casting is sealed in a sand box for insulation for 3 hours, and then opened to obtain a blank casting;

[0012] Step 5, heat treatment: heat treatment of the blank casting in a heat treatment furnace, put into the furnace at room temperature, heat up to 550°C at a heating rate of no more than 100°C / h, then keep the constant temperature for 3-4h, cool to 250-300°C with the furnace, and air cool after being taken out of the furnace;

[0013] Step six, the rough casting is processed by CNC to obtain the finished cast iron brake disc.

[0014] In the step 2, gradually increasing the power means that the power of the medium frequency induction furnace increases from 500kw to 1200kw within 1.2 hours.

[0015] Before pouring and secondary inoculation in step 4, multiple sand cores are stacked together to form a core group, and then the core group is placed in a lower sand mold made of green sand. Finally, the upper sand mold and the lower sand mold made of green sand are combined to form a sand box with a casting cavity, and then transported to the pouring position.

[0016] In the step three, the molten iron is poured in layers into the cavity formed by the core group and the sand mold, which means that the molten iron is poured into the cavity formed between different sand cores and the sand mold respectively, so pouring the molten iron into the cavity formed between each layer of sand cores and the sand mold forms a layered pouring of the molten iron.

[0017] Beneficial effects of the present invention:

[0018] The brake disc produced by the present invention adopts the green sand multi-layer stacking box process, which greatly improves the manufacturing efficiency and greatly reduces the cost compared with the single-layer brake disc; during the casting process, molten iron is poured layer by layer, and the molten iron fills the mold smoothly with a multi-layer sand core combination to ensure the size progress of the casting; holes are designed in the middle of all sand cores to form air chambers, ensuring that the casting has no air holes and is of excellent quality. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention.

[0020] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0022] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0023] Example 1

[0024] A casting method for producing a brake disc using a green sand multi-layer stacking process, comprising the following contents:

[0025] Step 1, smelting: the raw materials are 60# ferromanganese, 60# ferromolybdenum, electrolytic copper, high carbon chromium, electrolytic nickel, low sulfur recarburizer, recycled materials and car body scrap steel;

[0026] The above raw materials are added to the medium frequency induction furnace in the order of low sulfur carburizer, ferrosilicon, ferromanganese, ferromolybdenum, electrolytic copper, high carbon chromium, electrolytic nickel and scrap steel of the vehicle body for smelting, and the smelting power is gradually increased until the raw materials are completely melted into molten iron, and then the recycled materials and the remaining scrap steel of the vehicle body are added to the medium frequency induction furnace, and then the temperature is kept until all the materials are melted; so that the molten iron contains the following components, and the content of each component reaches the following standards, all calculated by weight percentage:

[0027] Carbon 3.72%, silicon 1.50% (before furnace, before furnace refers to the raw water in the furnace, after furnace refers to the silicon content when the molten iron is poured into the ladle / pouring ladle, and the inoculant needs to be added), 1.70% (after furnace), manganese 0.60%, chromium 0.15%, copper 0.55%, molybdenum 0.1%, nickel 0.19%, the rest is iron and unavoidable impurities;

[0028] Step 2, inoculation treatment: After all the charge is melted, the temperature is maintained at 1480°C to prepare for taking out of the furnace. When taking out of the furnace, add a silicon-barium inoculant of 0.4% of the weight of the molten iron into the casting ladle, and then pour the molten iron into the casting ladle, and take out of the furnace and inoculate at one time;

[0029] Step 3: pouring and secondary inoculation: pour the molten iron obtained from the inoculation in step 2 into the brake disc casting cavity formed by the sand mold made of the core group and the green sand in layers, with a pouring temperature of 1330°C.

[0030] -1390℃, during the pouring process, secondary inoculation is carried out, the inoculant is ferrosilicon inoculant (0.1-0.3mm), the amount of which is 75% ferrosilicon, which is 0.3-0.4% of the weight of the molten iron before pouring and inoculation (i.e., the molten iron obtained in step 1);

[0031] Step 4, insulation: After pouring and secondary inoculation, the obtained casting is sealed in a sand box for natural insulation for 3 hours, and then opened to obtain a blank casting. The measurement results are shown in Table 1;

[0032] Step 5, heat treatment: heat treatment of the blank casting in a heat treatment furnace, the heat treatment process parameters are: enter the furnace at room temperature, heat up to 550°C at a heating rate of no more than 100°C / h, then maintain constant temperature for 3-4h, cool to 250-300°C with the furnace, and air cool after being taken out of the furnace;

[0033] Step six, the rough casting is processed by CNC to obtain the finished cast iron brake disc.

[0034] In the step 2, gradually increasing the power means that the power of the medium frequency induction furnace increases from 500kw to 1200kw within 1.2 hours.

[0035] Before pouring and secondary inoculation in step 4, the lower core group is assembled and the cores are first stacked together to form a core group, and then the core group is placed in a lower sand mold made of green sand. Finally, the upper sand mold made of green sand and the lower sand mold are assembled to form a sand box with a casting cavity, and then transported to the pouring position.

[0036] In the step three, the molten iron is poured in layers into the cavity formed by the core group and the sand mold, which means that the molten iron is poured into the cavity formed between different sand cores and the sand mold respectively, so pouring the molten iron into the cavity formed between each layer of sand cores and the sand mold forms a layered pouring of the molten iron.

[0037] The brake disc is produced by multi-layer stacking box method. First, the core group method is adopted. Each core group can form a 4-layer casting cavity. Each mold can hold three core groups. The same pouring system is used between the core groups. In this way, each sand mold can produce more than 12 castings. 400 molds are produced per shift, and more than 4,800 castings can be produced. Each mold has 255Kg of molten iron, and the sand-to-iron ratio is improved. The weight of 12 castings in each mold reaches 192Kg, the process yield rate reaches more than 75%, and the cost is greatly reduced.

[0038] Example 2

[0039] A casting method for producing a brake disc using a green sand multi-layer stacking process, comprising the following contents:

[0040] 1) A high carbon brake disc smelting method, wherein the raw material components are calculated based on chemically pure content, and the weight percentage of each component is: carbon 3.72%, silicon 1.50% (before furnace) 1.70% (after furnace), manganese 0.60%, chromium 0.15%, copper 0.55%, molybdenum 0.1%, nickel 0.19%, and the rest is iron. The raw material components are 60# ferromanganese, 60# ferromolybdenum, electrolytic copper, high carbon chromium, electrolytic nickel, low sulfur recarburizer, recycled materials and car body scrap steel, and pig iron is not used.

[0041] The manufacturing method of the cast iron outer plate is as follows:

[0042] a. Ingredients: According to the above design requirements, first determine the chemical composition and percentage of each required raw material, then calculate the amount of the required raw material according to the chemical purity content, and weigh it for use;

[0043] b. Melting: Add weighed low-sulfur carburizer, ferrosilicon, ferromanganese, ferromolybdenum, electrolytic copper, low-carbon chromium, electrolytic nickel and scrap steel of the vehicle body into the furnace, and then heat it with a 2000kg medium-frequency induction furnace. The order of feeding is the same as above. The power is increased slowly, and the increase from 500kw to 1200kw is completed within 1.2 hours. After the molten iron is cleared, the return charge and the remaining scrap steel are added successively until all the charge is added, and then the temperature is kept until all the charge is melted; when the temperature of the molten iron reaches 1270 degrees Celsius, take the sample in front of the furnace for spectral analysis, and adjust the composition of the molten iron according to the spectral results.

[0044] c. Inoculation treatment: After all the materials are melted, the temperature is maintained at 1480℃ and ready to be taken out of the furnace. When taking out of the furnace, 0.4% silicon-barium inoculant is added to the pouring ladle and inoculated at one time.

[0045] d. Molding, core setting, and box closing: Make upper and lower molds, combine the sand cores to form the core group of the cavity of the multi-layer casting, put them into the lower sand mold, close the box, and form the cavity of the multi-layer casting and the pouring system. Transport to the pouring position.

[0046] e. Pouring and secondary inoculation treatment: The pouring temperature is 1330°C-1390°C. Before pouring, 0.3% 75 ferrosilicon inoculant (0.1-0.3mm) of the weight of the molten iron is added to the flow for secondary inoculation treatment;

[0047] f. Insulation: After pouring, seal the sand box and keep it warm for 3 hours. Then open the box to get the blank. The test results are shown in Table 1.

[0048] g. Heat treatment: The casting is heat treated in a heat treatment furnace. The heat treatment process parameters are: enter the furnace at room temperature, heat up to 550°C at a heating rate of no more than 100°C / h, then maintain a constant temperature for 3h-4h, cool down to 250-300°C with the furnace, and then take out of the furnace and air cool;

[0049] h. The blank is processed by CNC to obtain the finished cast iron brake disc.

[0050] The layered casting method is adopted, and the molten iron fills the mold cavity layer by layer. Sand core groups are used to form core groups between each layer of castings; the assembled core groups are placed in the green sand mold, and the brake disc casting is cast after the box is closed.

[0051] Table 1 Chemical composition and mechanical properties

[0052]

[0053] The preferred embodiments of the present invention are described in detail above. However, the protection scope of the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention. These simple variations all belong to the protection scope of the present invention.

[0054] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0055] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A casting method for producing brake discs using a green sand multi-layer stacking process, characterized in that: It includes the following: Step 1, smelting: the raw materials are ferromanganese, ferromolybdenum, electrolytic copper, high carbon chromium, electrolytic nickel, low sulfur recarburizer, recycled materials and car body scrap steel; The above raw materials are added to the medium frequency induction furnace in the order of low sulfur carburizer, ferrosilicon, ferromanganese, ferromolybdenum, electrolytic copper, high carbon chromium, electrolytic nickel and scrap steel of the vehicle body for smelting, and the smelting power is gradually increased until the raw materials are completely melted into molten iron, and then the recycled materials and the remaining scrap steel of the vehicle body are added to the medium frequency induction furnace, and then the temperature is kept until all the materials are melted; so that the molten iron contains the following components, and the content of each component reaches the following standards, all calculated by weight percentage: Carbon 3.72%, silicon 1.70%, manganese 0.60%, chromium 0.15%, copper 0.55%, molybdenum 0.1%, nickel 0.19%, the balance is iron and unavoidable impurities; Step 2, inoculation treatment: After all the charge is melted, the temperature is maintained at 1480°C to prepare for taking out of the furnace. When taking out of the furnace, add a silicon-barium inoculant of 0.4% of the weight of the molten iron into the casting ladle, and then pour the molten iron into the casting ladle, and take out of the furnace and inoculate at one time; Step 3, pouring and secondary inoculation treatment: pouring the molten iron obtained by inoculation in step 2 into the brake disc casting cavity formed by the sand mold made of the core group and the green sand in layers, the pouring temperature is 1330°C-1390°C, and secondary inoculation is performed during the pouring process. The inoculant is ferrosilicon inoculant, and the amount used is 0.3-0.4% of the weight of the molten iron before pouring and inoculation; Step 4, insulation: After pouring and secondary inoculation, the obtained casting is sealed in a sand box for insulation for 3 hours, and then opened to obtain a blank casting; Step 5, heat treatment: heat treatment of the blank casting in a heat treatment furnace, put into the furnace at room temperature, heat up to 550°C at a heating rate of no more than 100°C / h, then keep the constant temperature for 3-4h, cool to 250-300°C with the furnace, and air cool after being taken out of the furnace; Step six, the rough casting is processed by CNC to obtain the finished cast iron brake disc.

2. A casting method for producing brake discs using a green sand multi-layer stacking process according to claim 1, characterized in that: In the step 2, gradually increasing the power means that the power of the medium frequency induction furnace increases from 500kw to 1200kw within 1.2 hours.

3. The method for producing brake discs by using a green sand multi-layer stacking process according to claim 1, characterized in that: Before pouring and secondary inoculation in step 4, multiple sand cores are stacked together to form a core group, and then the core group is placed in a lower sand mold made of green sand. Finally, the upper sand mold and the lower sand mold made of green sand are combined to form a sand box with a casting cavity, and then transported to the pouring position.

4. The casting method for producing brake discs using a green sand multi-layer stacking process according to claim 1, characterized in that: In the step three, the molten iron is poured in layers into the cavity formed by the core group and the sand mold, which means that the molten iron is poured into the cavity formed between different sand cores and the sand mold respectively, so pouring the molten iron into the cavity formed between each layer of sand cores and the sand mold forms a layered pouring of the molten iron.

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