Method for preparing high-performance nodular cast iron grinding ball by combining ultrasonic vibration and water cooling method

Abstract

The invention discloses a method for preparing a high-performance nodular cast iron grinding ball by combining ultrasonic vibration and a water cooling method. The method comprises the following steps: S1, providing a sand mold; s2, the raw materials are put into a smelting furnace, and first alloy liquid is obtained after melting; s3, the first alloy liquid is poured into a spheroidizing bag, spheroidizing treatment and inoculation treatment are conducted, and second alloy liquid is obtained; s4, molding by casting; wherein the step S4 comprises the following sub-steps: S401, preheating the sand mold, then starting ultrasonic vibration, and introducing cooling water; s402, the second alloy liquid is poured into a sand mold; and S403, after the second alloy liquid is cooled, a pearlite matrix nodular cast iron grinding ball blank containing graphite nodules and carbides is prepared. According to the preparation method of the nodular cast iron grinding ball, the process cost is low, precious alloy elements are not added, and a subsequent complex and high-cost heat treatment process is not needed; and the prepared nodular cast iron grinding ball is low in breakage rate and suitable for large-scale production and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of grinding ball smelting and casting. Specifically, the present invention relates to a method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling method. Background Art

[0002] The ball mill is an important equipment in the crushing industry and has a wide range of applications in multiple industries such as metallurgy, building materials, mining, electric power, and chemical industry. As the main grinding medium of the ball mill, the grinding balls will break during use and are a consumable. Therefore, how to reduce the preparation cost and breakage rate of grinding balls has become an urgent problem to be solved.

[0003] Taking the commonly used ductile iron grinding balls as an example, the reasons for their high preparation cost and easy breakage are as follows: Sand casting of ductile iron is prone to uneven structure (coarse, segregation, shrinkage porosity), and its mechanical properties are poor. Usually, alloying elements need to be added and subsequent heat treatment is required to increase the amount of pearlite and improve the strength, which will lead to a long production cycle and high cost.

[0004] Chinese Patent with Application No. 202010356089.0 discloses a pouring method for ductile iron wheels, including the following steps: (1) Take a pouring mold with a cooling cavity outside the mold; (2) First, preheat the mold as a whole to 200 - 260 °C; (3) Before pouring the molten iron, perform nodulizing treatment and inoculation treatment. After inoculation treatment, skim the slag and then pour; (4) Control the molten iron temperature at 1430 - 1500 °C, pour the molten iron into the mold; after standing for 20 - 25 min, first introduce cold air into the cooling cavity for cooling, and after 25 - 35 min, then introduce cooling water into the cooling cavity for cooling. After the casting temperature drops to 300 - 350 °C, take out the casting and air-cool it to room temperature; finally, heat the casting cooled to room temperature to 930 - 960 °C, keep it warm for 3 - 4.5 h, first cool down to 750 - 780 °C, keep it warm for 30 - 60 min, then cool down to 360 - 410 °C, keep it warm for 1 - 2 h, air-cool it to room temperature, and then perform stress relief annealing to prepare the ductile iron wheel. Although this method uses cooling water to control the casting solidification process, in order to obtain high strength, a variety of alloying elements such as Ni, Cu, Zr, and Ti are added, and three-stage temperature heat treatment at 930 - 960 °C, 750 - 780 °C, and 360 - 410 °C and stress relief annealing are carried out, resulting in a high preparation cost of the grinding balls.

[0005] A Chinese patent with the application number 202010957030.7 discloses a high-strength and tough ductile iron and its preparation method. In this patent, steel plates and a cooling water system are added above and below the sand mold to adjust the cooling water temperature and the water flow rate, thereby controlling the cooling rate, regulating the casting structure, especially regulating the pearlite content, eliminating casting defects, without adding alloying elements such as Cu and Ni to increase the pearlite content and improve the mechanical properties, and without a heat treatment process. The castings prepared in this patent have excellent mechanical properties, achieving simultaneous improvement in tensile strength and plasticity, but ultrasonic-assisted regulation is not involved in this method. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling, aiming to reduce the preparation cost of ductile iron grinding balls.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling, comprising the steps of:

[0008] S1. Provide a sand mold;

[0009] S2. Put the raw materials into a melting furnace, and obtain a first alloy liquid after melting;

[0010] S3. Pour the first alloy liquid into a nodulizing ladle, perform nodulizing treatment and inoculation treatment to obtain a second alloy liquid;

[0011] S4. Cast and form;

[0012] Among them, the step S4 includes:

[0013] S401. Preheat the sand mold, then turn on ultrasonic vibration and introduce cooling water;

[0014] S402. Pour the second alloy liquid into the sand mold;

[0015] S403. After the second alloy liquid cools, obtain a pearlite matrix ductile iron grinding ball blank containing graphite balls and carbides.

[0016] The sand mold includes an ultrasonic vibration horn, a first mounting plate, a second mounting plate, and a sand mold disposed between the first mounting plate and the second mounting plate. The ultrasonic vibration horn is located below the first mounting plate.

[0017] The sand mold further includes a support plate. The ultrasonic vibration horn is disposed on the support plate, and the support plate is connected to the first mounting plate and the second mounting plate through adjustment bolts.

[0018] There is a set distance H between the first mounting plate and the end of the ultrasonic vibration horn, and the range of the set distance H is 5 - 10 mm.

[0019] Cooling water pipes are arranged inside the first mounting plate and the second mounting plate. There are multiple cooling water pipes, and the layout shape of the cooling water pipes is serpentine. The interval distance between adjacent two cooling water pipes is set at 10 - 15 mm.

[0020] In the step S401, cooling water is introduced into the sand mold. The temperature of the cooling water is 0 - 80 °C, and the flow rate is 1 - 10 m 3 / h; when the ultrasonic vibration is turned on, the power of the ultrasonic is 0.6 - 2 kW, and the action mode is continuous action.

[0021] In the step S2, the ductile iron grinding balls are composed of the following mass percentage components: C: 3.6 - 4.2%, Si: 2.0 - 2.5%, Mn: 0.6 - 1.2%, Cr 0.2 - 0.5%, P: ≤0.1%, S: ≤0.03%, Mg: 0.03 - 0.08%, and the balance is Fe.

[0022] In the step S2, the raw materials added to the melting furnace include steel for ductile iron, carburant, ferromanganese alloy, ferrochromium alloy, and ferrosilicon alloy;

[0023] During melting, first add the steel for ductile iron and the carburant. The melting temperature is 1400 °C. After the steel for ductile iron is completely melted, add the ferromanganese alloy, ferrochromium alloy, and ferrosilicon alloy, raise the temperature to 1500 °C, and finally pour out to obtain the first alloy liquid.

[0024] In the step S3, a spheroidizing agent and an inoculant are added to the spheroidizing ladle. The spheroidizing agent uses a rare earth ferrosilicon magnesium alloy with the mass percentage of elemental components being 5 - 7% Mg, 1 - 3% Re, 40 - 45% Si, and the rest being iron, and its addition amount is 1.1 - 1.8% of the mass of the first alloy liquid; the inoculant uses a barium-containing ferrosilicon alloy with the mass percentage of elemental components being 1 - 3% Ba, 70 - 75% Si, and the rest being iron, and its addition amount is 0.4 - 1.0% of the mass of the first alloy liquid;

[0025] The rare earth ferrosilicon magnesium alloy is located at the bottom layer, and the barium-containing ferrosilicon alloy is located at the upper layer;

[0026] First, pour 0.8 times the volume of the first alloy liquid into the spheroidizing ladle for spheroidizing and inoculating, and then pour the remaining first alloy liquid for spheroidizing and inoculating to obtain the second alloy liquid.

[0027] In the step S401, preheat the sand mold to 220 - 250 °C; in the step S402, the pouring temperature is 1360 - 1420 °C.

[0028] The method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling in the present invention has low process cost, does not add precious alloying elements, and does not require subsequent complex and costly heat treatment processes; moreover, the prepared ductile iron grinding balls have a small breakage rate and are suitable for large-scale production applications. Description of the Drawings

[0029] This specification includes the following drawings, and the shown contents are respectively:

[0030] Figure 1 is the flow chart of the preparation method of the ductile iron grinding balls of the present invention;

[0031] Figure 2 is the structural schematic diagram of the sand mold;

[0032] Figure 3 is the layout schematic diagram of the cooling water pipe;

[0033] The markings in the figure are:

[0034] 1. Ultrasonic vibration horn; 2. Support plate; 3. First mounting plate; 4. Second mounting plate; 5. Adjusting bolt; 6. Adjusting nut; 7. Sand mold; 8. Cooling water inlet; 9. Cooling water outlet; 10. Pouring gate; 11. Cooling water pipe. Detailed Embodiments

[0035] The following is a further detailed description of the specific embodiments of the present invention by describing the embodiments with reference to the drawings, aiming to help those skilled in the art have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitate its implementation.

[0036] It should be noted that in the following embodiments, the "first" and "second" do not represent an absolute distinction relationship in structure and / or function, nor do they represent the execution order, but are only for the convenience of description.

[0037] As Figure 1 shown, the present invention provides a method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling, including the following steps:

[0038] S1. Provide a sand mold;

[0039] S2. Put the raw materials into a melting furnace, and obtain a first alloy liquid after melting;

[0040] S3. Pour the first alloy liquid into a nodulizing ladle, perform nodulizing treatment and inoculation treatment to obtain a second alloy liquid;

[0041] S4. Cast and form.

[0042] Specifically, the object of the present invention is to provide a process flow and method for optimizing the structure and mechanical properties of nodular cast iron grinding balls by combining high-energy ultrasound and cooling water treatment in view of the problems of high cost and complex process in the preparation of existing sand-mold nodular cast iron grinding balls, which require the addition of alloying elements and subsequent heat treatment. On the one hand, when ultrasound propagates in the molten iron melt, cavitation effects, acoustic streaming and mechanical vibrations are generated, thereby refining the grain size, adjusting the morphology and improving the physical properties of nodular cast iron. On the other hand, a cooling water system is added to the upper and lower sides of the sand mold. By adjusting the cooling water temperature and the water flow rate, the cooling and solidification rate of the molten iron is controlled, and the structure of the casting is regulated, especially the pearlite content is regulated, and casting defects are eliminated.

[0043] In the present invention, the cooling and solidification processes of nodular cast iron grinding balls for casting are regulated by combining ultrasonic vibration and water cooling method, and subsequent heat treatment processes are not required, and high-performance casting grinding balls with low breakage rate can be directly obtained.

[0044] In the present invention, in a high-energy ultrasound and water cooling environment, the high-energy ultrasound effects (thermal effect, cavitation effect, acoustic streaming effect) of high-frequency ultrasound and cooling water are used to regulate the solidification process of molten iron, thereby effectively refining the structure of nodular cast iron, realizing the regulation of the structure and mechanical properties of the casting, and making the mechanical properties of nodular cast iron grinding balls excellent. The present invention enables sand-mold casting grinding balls not to add precious alloying elements and not to require subsequent complex and costly heat treatment processes, and has the advantages of simple method, low cost, high efficiency and energy saving.

[0045] Prepare a sand mold according to the size of the required grinding ball. As Figure 2 shown, the sand mold includes an ultrasonic vibration horn 1, a first mounting plate 3, a second mounting plate 4, and a sand mold 7 disposed between the first mounting plate 3 and the second mounting plate 4. A cavity is provided inside the sand mold 7. The second alloy liquid is added to the cavity of the sand mold 7. The ultrasonic vibration horn 1 is located below the first mounting plate 3. The sand mold 7 is fixedly mounted on the first mounting plate 3. The second mounting plate 4 is located above the sand mold 7. The first mounting plate 3 and the second mounting plate 4 are steel plates. Steel plates are added to the upper and lower sides of the sand mold 7, and serpentine cooling water channels are embedded in the steel plates. Cooling water is introduced into the cooling water channels, and the temperature and flow rate of the cooling water can be regulated; an array of ultrasonic vibration horns 1 is mounted at a certain distance from the bottom of the steel plate in the lower layer of the sand mold 7, waiting for the ultrasonic vibration to be turned on, and the ultrasonic frequency can be regulated; the sand mold 7 adopts a top-pouring gating system and waits for casting.

[0046] As Figure 2As shown, the sand mold also includes a support plate 2. The ultrasonic vibration horn 1 is arranged on the support plate 2. A plurality of ultrasonic vibration horns 1 are provided. The support plate 2 is connected to the first mounting plate 3 and the second mounting plate 4 through a connecting mechanism. The distance between the first mounting plate 3 and the ultrasonic vibration horn 1 is adjustable. The connecting mechanism mainly includes adjusting bolts 5 and adjusting nuts 6 threadedly connected to the adjusting bolts 5. A plurality of adjusting bolts 5 are provided, and a plurality of adjusting nuts 6 are provided on the adjusting bolts 5. Mounting holes for the adjusting bolts 5 to pass through are provided on the support plate 2, the first mounting plate 3, and the second mounting plate 4. Adjusting nuts 6 are provided above and below the mounting holes on the support plate 2, above and below the mounting holes on the first mounting plate 3, and above and below the mounting holes on the second mounting plate 4. After tightening the adjusting bolts 5, the support plate 2, the first mounting plate 3, and the second mounting plate 4 can be fixed on the adjusting bolts 5.

[0047] As Figure 2 shown, the ultrasonic vibration horn 1 is arranged directly below the bottom of the first mounting plate 3. The ultrasonic vibration horn 1 is connected to the adjusting bolt 5 through the support plate 2, and the installation distance H of the ultrasonic probe can be adjusted through the adjusting bolt 5. The arrangement direction of the ultrasonic vibration horn 1 is along the center line direction of the first mounting plate 3. The number of the array-mounted ultrasonic vibration horns 1 ranges from 5 to 8. The arrangement interval between two adjacent ultrasonic vibration horns 1 is 8 - 10 mm. A set distance H is provided between the first mounting plate 3 and the end of the ultrasonic vibration horn 1. The set distance H ranges from 5 to 10 mm. Exemplarily, the set distance H can be 6 mm, 7 mm, 8 mm, or 9 mm.

[0048] Preferably, the thicknesses of the first mounting plate 3 and the second mounting plate 4 are 20 mm.

[0049] As Figure 2 and Figure 3 shown, cooling water pipes 11 are arranged inside the first mounting plate 3. A plurality of cooling water pipes 11 are provided. The arrangement shape of the cooling water pipes 11 is serpentine. All the cooling water pipes 11 are connected in sequence to form a serpentine cooling water channel inside the first mounting plate 3. Cooling water is introduced into the cooling water channel. The interval distance between two adjacent and parallel cooling water pipes 11 is set at 10 - 15 mm. The inner diameter of the cooling water pipes 11 is 8 mm. A cooling water inlet 8 and a cooling water outlet 9 are provided on the first mounting plate 3. The cooling water inlet 8 and the cooling water outlet 9 are respectively located at both ends of the cooling water channel. The cooling water inlet 8 and the cooling water outlet 9 are arranged on the same side of the first mounting plate 3.

[0050] As Figure 2 and Figure 3As shown in the figure, a cooling water pipe 11 is arranged inside the second mounting plate 4. A plurality of cooling water pipes 11 are provided, and the arrangement shape of the cooling water pipes 11 is serpentine. All the cooling water pipes 11 are connected in sequence to form a serpentine cooling water channel in the first mounting plate 3. Cooling water is introduced into the cooling water channel. The interval distance between two adjacent and parallel cooling water pipes 11 is set at 10 - 15 mm, and the inner diameter of the cooling water pipe 11 is 8 mm. A cooling water inlet 8 and a cooling water outlet 9 are arranged on the second mounting plate 4. The cooling water inlet 8 and the cooling water outlet 9 are respectively located at both ends of the cooling water channel, and the cooling water inlet 8 and the cooling water outlet 9 are arranged on the same side of the second mounting plate 4.

[0051] In the above step S2, batching is carried out according to the mass percentage of the element components of the ductile iron grinding balls. The batched raw materials (including steel, carburant, ferromanganese, ferrochrome, ferrosilicon) are put into an intermediate frequency induction melting furnace and heated and melted until all the raw material components are completely melted to obtain the first alloy liquid.

[0052] In the above step S2, the ductile iron grinding balls are composed of the following mass percentage components: C: 3.6 - 4.2%, Si: 2.0 - 2.5%, Mn: 0.6 - 1.2%, Cr 0.2 - 0.5%, P: ≤0.1%, S: ≤0.03%, Mg: 0.03 - 0.08%, and the balance is Fe.

[0053] In the above step S2, the raw materials added to the melting furnace include steel for ductile iron, carburant, ferromanganese alloy, ferrochrome alloy, and ferrosilicon alloy. The steel for ductile iron can be pig iron or scrap steel.

[0054] In the above step S2, during melting, first, the steel for ductile iron and the carburant are added to the melting furnace, and the melting temperature is 1400°C. After the steel for ductile iron is completely melted, ferromanganese alloy, ferrochrome alloy, and ferrosilicon alloy are added to the melting furnace, and the temperature is raised to 1500°C. Finally, the first alloy liquid is taken out of the furnace.

[0055] In the above step S2, the melting furnace is an induction electric furnace, and the melting is carried out in the induction electric furnace. The carburant is selected from one of petroleum coke powder or pitch coke powder, and the melting temperature is 1400 - 1600°C.

[0056] In the above step S3, the first alloy liquid prepared in step S2 is poured into a spheroidizing ladle added with a spheroidizing agent and an inoculant for spheroidizing treatment and inoculation treatment to obtain the second alloy liquid. A slag removing agent is added in the later stage of the reaction for heat preservation and slag agglomeration.

[0057] In the above step S3, a spheroidizing agent and an inoculant are added to the spheroidizing ladle. The spheroidizing agent is a rare earth ferrosilicon magnesium alloy with the mass percentages of elemental components being 5-7% Mg, 1-3% Re, 40-45% Si, and the balance being iron, and its addition amount is 1.1-1.8% of the mass of the first alloy liquid; the inoculant is a barium-containing ferrosilicon alloy with the mass percentages of elemental components being 1-3% Ba, 70-75% Si, and the balance being iron, and its addition amount is 0.4-1.0% of the mass of the first alloy liquid.

[0058] In the above step S3, a rare earth ferrosilicon magnesium alloy and a barium-containing ferrosilicon alloy are placed in the spheroidizing ladle. Among them, the rare earth ferrosilicon magnesium alloy is located at the bottom layer, and the barium-containing ferrosilicon alloy is located at the upper layer. The spheroidizing and inoculating temperature range is 1400-1600 °C; the slag remover should cover the entire surface of the second alloy liquid, and the temperature is maintained above 1400 °C.

[0059] In the above step S3, first, 0.8 times the volume of the first alloy liquid is poured into the spheroidizing ladle for spheroidizing and inoculating, and then the remaining first alloy liquid is poured in for spheroidizing and inoculating to obtain the second alloy liquid.

[0060] In the above step S4, before pouring, the metal mold is preheated, then ultrasonic vibration is started and cooling water is introduced; the austenitic ductile iron alloy liquid treated by spheroidizing and inoculating is poured into the metal mold with coated sand; the treated austenitic ductile iron base iron liquid is cooled to obtain a pearlite matrix ductile iron grinding ball containing graphite balls and carbides, so that the molten iron is quickly cooled and solidified; when the riser turns pink, the mold is opened to drop the ball to obtain a grinding ball blank.

[0061] The above step S4 includes:

[0062] S401. Preheat the sand mold, then start ultrasonic vibration and introduce cooling water;

[0063] S402. Pour the second alloy liquid into the sand mold;

[0064] S403. After the second alloy liquid is cooled, a pearlite matrix ductile iron grinding ball blank containing graphite balls and carbides is obtained.

[0065] Preferably, in the above step S401, cooling water is introduced into the sand mold, and the cooling water enters the cooling water channels in the first mounting plate 3 and the second mounting plate 4. The temperature of the cooling water is 0-80 °C, and the flow rate is 1-10 m 3 / h; when starting ultrasonic vibration, the power of the ultrasonic wave is 0.6-2 kW, and the action mode is continuous action.

[0066] Preferably, in the above step S401, the sand mold is preheated to 220-250 °C.

[0067] Preferably, in the above step S402, the pouring temperature is 1360-1420°C.

[0068] Preferably, during the ball grinding process, the ambient temperature is 0-40°C.

[0069] Preferably, the diameter of the ductile iron grinding balls is 60-150 mm.

[0070] Preferably, a grinding ball with a diameter of 100 mm is selected to prepare the sand mold.

[0071] The preparation method of ductile iron grinding balls has the following advantages:

[0072] 1. The present invention creatively applies ultrasonic intervention technology to the solidification process of alloy liquid, and combines cooling water to effectively regulate and refine the structure of ductile iron grinding balls, which can realize the regulation of solidification and cooling process, thereby realizing the regulation of casting structure and mechanical properties, and can make the ductile iron grinding balls have good plasticity requirements while having high strength.

[0073] 2. The present invention makes it unnecessary to add precious alloy elements to the sand casting grinding balls, and does not require subsequent complex and costly heat treatment processes, thus shortening the process flow, simplifying the method, facilitating mass production, and having the advantages of low manufacturing cost, high efficiency and energy saving, etc.

[0074] 3. The ductile iron grinding balls prepared by the method of the present invention have a small breakage rate, a long service life, and reduced costs.

[0075] Example 1

[0076] This embodiment provides a method for preparing high-performance ductile iron grinding balls by combining ultrasonic coagulation and water cooling, comprising the following steps:

[0077] (1) Select a grinding ball with a diameter of 100 mm to prepare a sand mold; add steel plates with a thickness of 20 mm on the upper and lower sides of the sand mold; fix a cooling water pipe on the steel plate with an inner diameter of 8 mm; install an array ultrasonic vibration amplitude transformer 1 at a distance of 6 mm from the bottom of the steel plate on the lower layer of the sand mold, and wait for ultrasonic vibration to be turned on; use a top pouring system and wait for casting;

[0078] (2) the raw materials are prepared according to the percentage of the components, wherein the ductile iron has a C content of 3.8%, a Si content of 2.2%, a Mn content of 0.9%, a Cr content of 0.4%, a P content of 0.05%, a S content of 0.03%, a Mg content of 0.05%, and the balance of Fe; a medium frequency induction furnace is used for smelting, and firstly, steel for ductile iron and a carburizer are added, and the smelting temperature is 1400° C. After the ductile iron is completely melted, ferromanganese and ferrosilicon alloy are added, and the temperature is raised to 1500° C. to obtain a first alloy liquid;

[0079] The carburizer is selected from petroleum coke powder; the nodulizer is a rare earth ferrosilicon magnesium alloy with a mass percentage of elemental components of 7% Mg, 2% Re, 40% Si, and the rest being iron, and its addition amount is 1.8% of the mass of the original ferritic ductile iron liquid; the inoculant is a barium-containing ferrosilicon alloy with a mass percentage of elemental components of 2% Ba, 72% Si, and the rest being iron, and its addition amount is 0.4% of the mass of the original ferritic ductile iron liquid.

[0080] (3) Pour the first alloy liquid into a ladle already added with the nodulizer and inoculant for nodulizing treatment to obtain a second alloy liquid, where the nodulizing and inoculating temperature is 1400 °C; add a slag removing agent after 5 minutes for heat preservation and slag agglomeration, and the slag removing agent covers the entire surface of the molten iron, and the temperature of the alloy liquid is kept above 1400 °C;

[0081] (4) Preheat the metal mold to 230 °C; pour the second alloy solution from the sprue cup of the sand mold, and the casting temperature is 1360 °C; control the temperature of the cooling water to be 10 °C, the flow rate to be 8 m 3 / h, and the power of the ultrasonic wave to be 1 kW to cool and solidify the alloy liquid to obtain grinding balls.

[0082] Comparative Example 1

[0083] Except that the temperature of the cooling water is 10 °C, the flow rate is 8 m 3 / h, and the power of the ultrasonic wave is 0 kW, the rest is the same as in Example 1.

[0084] Comparative Example 2

[0085] Except that the flow rate of the cooling water is 0 m 3 / h, and the power of the ultrasonic wave is 8 kW, the rest is the same as in Example 1.

[0086] Comparative Example 3

[0087] Except that the flow rate of the cooling water is 0 m 3 / h, and the power of the ultrasonic wave is 0 kW, the rest is the same as in Example 1.

[0088] Testing method for breakage rate:

[0089] Use a ball mill with a diameter of 5 m and the prepared ductile iron grinding balls for grinding for 3000 hours. After the grinding is completed, sort out and discharge the broken ductile iron grinding balls, and calculate the breakage rate by the following method: the mass of the broken ductile iron grinding balls / the total mass of the used ductile iron grinding balls.

[0090] Perform breakage performance tests on the ductile iron grinding balls prepared in the examples and comparative examples respectively, and the test results are as follows:

[0091] Serial number Crushing ratio (%) Example 1 0.15 Comparative Example 1 0.28 Comparative Example 2 0.32 Comparative Example 3 0.43

[0092] It can be seen that the method of the present invention can obtain austempered ductile iron grinding balls with a low breakage rate.

[0093] The present invention has been described by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention; or without improvement, and the above concept and technical solution of the present invention are directly applied to other occasions, they are all within the protection scope of the present invention.

Claims

1. A method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling method, characterized in that, It includes the steps: S1. Provide a sand mold; S2. Put the raw materials into a melting furnace, melt them to obtain the first alloy liquid; S3. Pour the first alloy liquid into a nodulizing ladle, conduct nodulizing treatment and inoculation treatment to obtain the second alloy liquid; S4. Cast and form; Among them, the step S4 includes: S401. Preheat the sand mold, then turn on ultrasonic vibration and introduce cooling water; S402. Pour the second alloy liquid into the sand mold; S403. After the second alloy liquid cools, obtain a pearlitic matrix ductile iron grinding ball blank containing graphite balls and carbides.

2. The method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling according to claim 1, characterized in that The sand mold includes an ultrasonic vibration horn, a first mounting plate, a second mounting plate, and a sand mold disposed between the first mounting plate and the second mounting plate. The ultrasonic vibration horn is located below the first mounting plate.

3. The method for preparing high-performance ductile iron grinding balls by the combined ultrasonic vibration and water cooling method according to claim 2, characterized in that, The sand mold further includes a support plate. The ultrasonic vibration horn is disposed on the support plate, and the support plate is connected to the first mounting plate and the second mounting plate through adjusting bolts.

4. The method for preparing high-performance ductile iron grinding balls by the combined ultrasonic vibration and water cooling method according to claim 2, characterized in that A set distance H is provided between the end of the first mounting plate and the ultrasonic vibration horn, and the range of the set distance H is 5 - 10 mm.

5. The method for preparing high-performance ductile iron grinding balls by the combined ultrasonic vibration and water cooling method according to claim 2, characterized in that, Cooling water pipes are arranged inside the first mounting plate and the second mounting plate. There are multiple cooling water pipes, and the arrangement shape of the cooling water pipes is serpentine. The interval distance between adjacent two cooling water pipes is set at 10 - 15 mm.

6. The method for preparing high-performance ductile iron grinding balls by the combined ultrasonic vibration and water cooling method according to any one of claims 1 to 5, characterized in that, In the step S401, cooling water is introduced into the sand mold, the temperature of the cooling water is 0 - 80 °C, and the flow rate is 1 - 10 m 3 / h; when ultrasonic vibration is turned on, the power of the ultrasonic wave is 0.6 - 2 kW, and the action mode is continuous action.

7. The method for preparing high-performance ductile iron grinding balls by the combined ultrasonic vibration and water cooling method according to any one of claims 1 to 6, characterized in that, In the step S2, the ductile iron grinding ball is composed of the following mass percentage components: C: 3.6 - 4.2%, Si: 2.0 - 2.5%, Mn: 0.6 - 1.2%, Cr 0.2 - 0.5%, P: ≤0.1%, S: ≤0.03%, Mg: 0.03 - 0.08%, and the balance is Fe.

8. The method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling according to any one of claims 1 to 7, characterized in that, In the step S2, the raw materials added to the melting furnace include steel for ductile iron, a carbon additive, ferromanganese alloy, ferrochrome alloy, and ferrosilicon alloy; During melting, first add the steel for ductile iron and the carbon additive. The melting temperature is 1400°C. After the steel for ductile iron is completely melted, add ferromanganese alloy, ferrochrome alloy, and ferrosilicon alloy, raise the temperature to 1500°C, and finally take out the furnace to obtain the first alloy liquid.

9. The method for preparing high-performance ductile iron grinding balls by the combined ultrasonic vibration and water cooling method according to any one of claims 1 to 8, characterized in that, In the step S3, a nodulizer and an inoculant are added to the nodulizing ladle. The nodulizer is a rare earth ferrosilicon magnesium alloy with the mass percentage of element components being 5 - 7% Mg, 1 - 3% Re, 40 - 45% Si, and the balance being iron, and its addition amount is 1.1 - 1.8% of the mass of the first alloy liquid; the inoculant is a barium-containing ferrosilicon alloy with the mass percentage of element components being 1 - 3% Ba, 70 - 75% Si, and the balance being iron, and its addition amount is 0.4 - 1.0% of the mass of the first alloy liquid; The rare earth ferrosilicon magnesium alloy is located at the bottom layer, and the barium-containing ferrosilicon alloy is located at the upper layer; First, pour 0.8 times the volume of the first alloy liquid into the nodulizing ladle for nodulizing and inoculating, and then pour the remaining first alloy liquid for nodulizing and inoculating to obtain the second alloy liquid.

10. The method for preparing high-performance ductile iron grinding balls by combining ultrasonic vibration and water cooling according to any one of claims 1 to 9, characterized in that, In the step S401, preheat the sand mold to 220 - 250°C; in the step S402, the casting temperature is 1360 - 1420°C.

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