A method for preparing metal abrasive specially used for aluminum products

Abstract

A method for preparing a special metal abrasive for aluminum products belongs to the technical field of metal abrasive production. The method comprises the following steps: (1) deoxidizing the molten steel with aluminum, and then centrifugally granulating the molten steel to obtain a semi-finished metal abrasive; (2) drying, tempering, cooling, strengthening, and screening the semi-finished metal abrasive to obtain a special metal abrasive for aluminum products; wherein the cooling is performed by air cooling using an air separation device. The special metal abrasive for aluminum products of the present invention has a low oxide scale content, a bright white and uniform appearance, and a long service life.

Description

Technical Field

[0001] The invention belongs to the technical field of metal abrasive production, and in particular relates to a method for preparing a special metal abrasive for aluminum products. Background Art

[0002] At present, the commonly used method for surface treatment in the manufacturing process of aluminum alloy is sandblasting. However, when sandblasting aluminum parts, the selection of sand grains is very critical. Different sand grains have different grinding effects and surface effects. Improper selection will cause the color to turn black and pollute the surface of the aluminum alloy after sandblasting. The existing low-carbon steel shot, high-carbon cast steel shot and low-carbon steel shot have low whiteness, and the results of the salt spray test show more rust spots. This is because low-carbon steel shot, high-carbon steel shot and low-carbon steel shot are all metal abrasives made of carbon steel. There are iron ions remaining after sandblasting, so they will rust after the blue dot test and salt spray test. At present, the abrasives used in the aluminum products industry are mainly made of stainless steel 410, 430, and 304. Although there is no iron ion residue after sandblasting of stainless steel shot, its process is relatively complicated, with low production capacity and high cost. In addition, the oxide scale produced during the preparation process will lead to reduced corrosion resistance, rough appearance, reduced quality, and reduced life, which cannot meet the needs of rapidly developing aluminum alloy products. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a special metal abrasive for aluminum products. The special metal abrasive for aluminum products of the present invention has low oxide scale content, bright white and uniform appearance, and long service life.

[0004] The technical solution adopted by the present invention to solve the technical problem is: to provide a method for preparing a special metal abrasive for aluminum products, comprising the following steps:

[0005] The method comprises the following steps: (1) deoxidizing the molten steel with aluminum and then centrifugally granulating the molten steel to obtain a semi-finished metal abrasive; (2) drying, tempering, cooling, strengthening and screening the semi-finished metal abrasive to obtain a special metal abrasive for aluminum products;

[0006] Wherein, the cooling is performed by air cooling using air selection equipment.

[0007] The structure of the material will change during the tempering process, and tempering can reduce its hardness and brittleness and improve toughness. The applicant found in the research and development that if the liquid nitrogen cooling temperature is too low and the cooling speed is too fast, cracks are likely to occur; if water is used for cooling, the water cannot directly contact the metal abrasive semi-finished product, and the cooling effect is poor. The cooling in this application is carried out in the air separation equipment, which can remove the oxide scale and reduce the temperature.

[0008] The cooling in step (2) is carried out in an air separation device, which includes an air separation device shell, a sieve plate and a high-pressure fan. An air separation feed port and an air separation discharge port are respectively arranged on both sides of the air separation device shell. The sieve plate is arranged in the air separation device shell, and the sieve plate is gradually inclined downward from the air separation feed port to the air separation discharge port. A plurality of nozzles are arranged on the upper side of the sieve plate. An air inlet is arranged at the bottom of the air separation device shell. The high-pressure fan is connected to the air inlet. An air outlet connected to a dust collection duct is arranged on the upper part of the air separation device shell, and a maze is arranged between the sieve plate and the air outlet.

[0009] The high-pressure fan blows in high-pressure cold air, which enters the bottom of the air separation equipment through the air inlet, and then enters the upper part of the sieve plate through the hole on the nozzle; the function of the nozzle is to divide the wind of the high-pressure fan into multiple streams and spray them out through the nozzle; the tempered metal abrasive semi-finished products enter through the air separation feed port to exchange heat with the high-pressure cold air of the air separation equipment, directly contact with the high-pressure cold air, and heat transfer reduces the temperature, so that the metal abrasive semi-finished products are cooled; the metal abrasive semi-finished products are lifted up by the high-pressure cold air and present a "boiling" state. The oxide scale in the metal abrasive semi-finished products is taken away by the wind in the "boiling" state. This is because the density of the oxide scale is less than that of the metal abrasive semi-finished products. The high-pressure cold air can take away the oxide scale, thereby ensuring that the appearance color of the product is better. The color of the oxide scale is black, and the color of steel after rusting is black and yellow. Visual inspection can determine whether the oxide scale is taken away by the wind of the fan.

[0010] The semi-finished metal abrasive is cooled in the air separation equipment at a rate of 70~190℃ / min to ≤80℃, and leaves the air separation equipment from the air separation outlet; the cooling time is 2~4min; too fast a cooling rate will increase its brittleness and make it easy to break; too slow a cooling rate will cause its overall hardness value to decrease.

[0011] The labyrinth includes a first baffle and a second baffle, both of which are inclined, and the first baffle and the second baffle are inclined in opposite directions, and the two ends of the second baffle are respectively located directly below two adjacent first baffles. The existence of the labyrinth increases the time that the high-pressure cold air stays in the air separation device, and the contact time between the metal abrasive semi-finished product and the high-pressure cold air increases, which further cools the product.

[0012] The maze increases the time that the high-pressure cold air stays in the air separation equipment, and the contact time between the metal abrasive semi-finished products and the high-pressure cold air increases, leading to further cooling. After cooling, the metal abrasive semi-finished products fall freely onto the sieve plate, and the sieve plate has a certain inclination angle from left to right. Under the action of wind force and the inclination angle of the sieve plate, the metal abrasive semi-finished products move from left to right on the sieve plate and leave the air separation equipment from the air separation outlet.

[0013] The upper end of the nozzle is closed, and a plurality of transverse ventilation holes are arranged on the side of the nozzle; the transverse ventilation holes are arranged to prevent the semi-finished metal abrasives on the screen plate from entering the nozzle and causing nozzle blockage.

[0014] The strengthening in step (2) is carried out in a strengthening device, which includes a strengthening mechanism, a conveyor and a storage bin; the strengthening mechanism is composed of a strengthening drive motor, a distributor and a liner; the conveyor and the storage bin are connected, the storage bin is connected to the strengthening mechanism, the strengthening drive motor is connected to the distributor, the liner and the distributor are arranged opposite to each other, and the strengthening drive motor provides centrifugal force for the distributor in the strengthening mechanism to directly eject the metal abrasive semi-finished product onto the liner for strengthening.

[0015] The semi-finished metal abrasive enters from the strengthening feed port, passes through the conveyor to the storage bin, adjusts the flow rate of the storage bin, and enters the distributor of the strengthening equipment. The semi-finished metal abrasive in the distributor is ejected onto the lining plate under the action of strong centrifugal force for strengthening. The strengthened semi-finished metal abrasive falls onto the conveyor, and is lifted to the storage bin again through the conveyor. This cycle is repeated to complete the strengthening process.

[0016] The strengthening time is 1 to 2.5 hours. If the strengthening time is too short, the strengthening effect and corrosion resistance are poor. If the strengthening time is too long, more breakage will occur.

[0017] The strengthening drive motor provides power to eject the semi-finished metal abrasives in the distributor onto the lining for strengthening. The ejection amount is 220~260kg / min, the sweeping speed is 85~95m / s, and the ejection distance is 0.05~0.15m. Since the materials are directly swept onto the lining after the materials are divided, the ejection distance is only 0.05~0.15m, and there is no speed reduction. The ejection speed is relatively high, and a thicker compressive stress layer can be obtained, and the stress corrosion resistance is relatively strong. If the ejection amount is too large, excessive deformation or damage will occur, affecting the surface quality; if the ejection amount is too small, the production efficiency will be low. If the sweeping speed is too fast, the impact force on the surface will increase, causing cracks or damage on the surface; if the sweeping speed is too slow, the strengthening effect will be affected. If the ejection distance is too large and the speed is reduced, a thicker compressive stress layer cannot be obtained, and the stress corrosion resistance is relatively poor.

[0018] At the same time, strengthening removes harmful substances, such as surface oxide scale and rust, to prevent harmful substances from causing further damage to the special metal abrasive for aluminum products during subsequent use. On the other hand, strengthening can increase the roughness and surface area of ​​the surface, which is beneficial to prevent the erosion of corrosive media, so the special metal abrasive for aluminum products can obtain stronger corrosion resistance; within a certain time range, the longer the strengthening time, the more conducive it is to improve its rust resistance and appearance whiteness and uniformity. After strengthening, there is no iron ion residue on the surface of the workpiece of the special metal abrasive for aluminum products, so its rust resistance is better. The special metal abrasive for aluminum products of the present invention can make the surface of aluminum products white and bright, and will not cause the workpiece to rust after spraying, and its price is much lower than stainless steel.

[0019] The special metal abrasive for aluminum products of the present application includes the following components, measured in percentage by mass: C0.005~0.075%, Si0.03~0.6%, Mn0.1~0.8%, S0~0.02%, P0~0.02, Cr0.05~0.3%, Al0.01~0.1%, Cu0.10~0.30%, Co0.001~0.06%, Mo0.01~0.5% and N0.01~0.03%, and the rest is iron and unavoidable impurities.

[0020] The lower the carbon content, the fewer the number of iron-carbon galvanic cells and the less rust. The workpiece looks whiter and brighter during sandblasting, and the overall anti-rust performance is better. The above-mentioned iron-carbon galvanic cell refers to an iron-carbon alloy, with carbon as the positive electrode and iron as the negative electrode. The oxygen and water vapor in the air gain electrons at the positive electrode, and the iron is oxidized at the negative electrode. The higher the carbon content, the more galvanic cells there are and the faster the corrosion.

[0021] Silicon manganese oxide is gray-brown in color, with low silicon and manganese content. Less silicon manganese oxide is produced during smelting and granulation, which can improve the appearance of metal abrasives specially used for aluminum products.

[0022] The cobalt element contained in the raw materials can improve the antioxidant ability, reduce oxidation, and can reduce the content of oxide scale in metal abrasives specially used for aluminum products, especially reduce the content of oxide scale in metal abrasives specially used for aluminum products with a particle size of ≤0.3mm, and improve the whiteness of the product; oxide scale is a corrosion product formed by oxidation of steel at high temperature, and is composed of ferrous oxide, ferroferric oxide and ferric oxide, which are ferrous oxide, ferroferric oxide and ferric oxide from the inside to the outside.

[0023] Aluminum can play a role in deoxidation and reduce oxidation. At the same time, it forms a dense aluminum oxide film in the metal abrasives specially used for aluminum products to improve corrosion resistance. Aluminum can also be combined with silicon, molybdenum, copper, and chromium elements to further improve the corrosion resistance.

[0024] Metal abrasives specially made for aluminum products have certain brittleness and strength. When reasonable nitrogen content and appropriate tempering post-treatment meet the spraying strength requirements of aluminum products, nitrogen can make the grain boundaries in the steel finer and form nitride phases, thereby effectively improving the hardness and toughness of the steel and giving it a longer service life.

[0025] The smelting temperature is 1640~1660℃, the smelting time is 1~2h, the electric furnace used for smelting is an electric arc furnace, and decarburization is carried out during smelting to reduce the carbon content.

[0026] The pouring temperature of the centrifugal granulation is 1480-1520° C., and the pouring speed is 280-350 kg / min. The low temperature of the centrifugal granulation can reduce the secondary oxidation of the molten steel.

[0027] The centrifugal granulation in step (1) is carried out in a closed granulation tank, in which a centrifugal disc is provided and a cover plate is provided on the upper part of the closed granulation tank.

[0028] The centrifugal granulation in step (1) is carried out in a closed granulation tank, and the granulation is close to an oxygen-free environment to reduce the oxidation of molten steel; the diameter of the centrifugal disk is 250 mm, and the frequency modulation range of the centrifuge is 22-45 Hz.

[0029] In step (1), molten steel is obtained and hoisted to the top of the centrifugal disk in the middle area of ​​the closed granulation pool. The centrifugal disk is driven to rotate around the central axis by a granulation drive motor. After the molten steel is poured into the centrifugal disk, it is thrown out by centrifugal force. The molten steel shrinks and forms, falls into the closed granulation pool, and is cooled to form a semi-finished aluminum product special metal abrasive. The granulation drive motor controls the synchronous belt wheel to move the synchronous belt and the connecting frame to drive the cover plate to open and close. The cover plate is a high temperature resistant cover plate. When pouring and granulating, the cover plate is closed to reduce the entry of oxygen. After the granulation is completed, the cover plate is opened, and the driving crane uses an electromagnet to enter the granulation pool from the cover plate to pick up the metal abrasive semi-finished product.

[0030] The tempering temperature is 350~450℃, and the tempering time is 40~60min; the tempering temperature is in the range of 350~450℃, and the tempering time mainly affects the metallographic structure of the product, and the appearance is hardness. If the tempering time is too short, the hardness after tempering will be uneven. If the tempering time is too long, the hardness will be too low. Too low hardness will cause easy wear and breakage during use, which will reduce work efficiency. Preferably, the tempering temperature is 390~410℃, and the tempering time is 45~55min; the preferred tempering temperature and time can reduce the hardness to 210~240HV, so that it has a longer life. The hardness of aluminum products is generally 200HV, so the hardness of the special metal abrasive for aluminum products in this application is in the range of 210~240HV, which can meet its hardness requirements.

[0031] The sieving in step (2) to any particle size of 0.05-0.15 mm, 0.1-0.2 mm, 0.15-0.25 mm, 0.2-0.3 mm, 0.3-0.5 mm and ≥0.5 mm meets the requirements of spray coverage and roughness of aluminum products; the industry requires that the coverage rate needs to reach more than 90%, and the roughness needs to reach Ra3.2-6.3 um. Metal abrasives of different particle sizes are selected according to different workpieces.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The air separation equipment of the present invention can complete air separation and cooling at the same time; the material temperature after cooling is ≤80°C, and the oxide scale is taken away by the wind in the "boiling" state during the cooling process, which can reduce the oxide scale content and make the appearance white, bright and uniform.

[0034] 2. The strengthening equipment of the present invention can obtain a thicker compressive stress layer, thereby having good corrosion resistance; and is conducive to a bright and uniform appearance.

[0035] 3. The carbon content of the present invention is low, and the number of iron-carbon primary cells formed is small, which is beneficial to enhancing its corrosion resistance and making its appearance white, bright and uniform.

[0036] 4. The special metal abrasive for aluminum products of the present invention has a simple preparation process, low cost and long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a bird's-eye view of the equipment for the closed granulation pool.

[0038] Figure 2 This is the main view of the air selector equipment.

[0039] Figure 3 This is the left view of the air selector equipment.

[0040] Figure 4 This is a bird's-eye view of the air selector equipment.

[0041] Figure 5 This is a partial view of the nozzle of the air separator equipment.

[0042] Figure 6 This is the main equipment diagram of the strengthening machine.

[0043] Figure 7 This is the left view of the strengthening machine equipment.

[0044] Figure 8 This is a diagram of the material distributor for the strengthening machine.

[0045] Among them: 1. casting platform 2, centrifugal disc 3, connecting frame 4, cover plate 5, synchronous belt 6, synchronous pulley 7, granulation drive motor 8, air selection feed port 9, air inlet 10, sieve plate 11, nozzle 12, air outlet 13, air selection discharge port 14, maze 15, high-pressure fan 16, air selector housing 17, ventilation hole 18, reinforced feed port 19, conveyor 20, storage bin 21, reinforced discharge port 22, reinforced drive motor 23, distributor 24, lining plate. DETAILED DESCRIPTION

[0046] Figures 1 to 8 The best embodiment of the present invention is shown below in conjunction with the attached Figures 1 to 8 The present invention is further described.

[0047] See also Figure 1 A centrifugal disc 2 is provided in the closed granulation pool, and a cover plate 4 is provided on the upper part of the closed granulation pool.

[0048] See also Figures 2~5 The air separation equipment includes an air separator housing 16, a sieve plate 10 and a high-pressure fan 15. An air separation feed port 8 and an air separation discharge port 13 are respectively arranged on both sides of the air separator housing 16. The sieve plate 10 is arranged in the air separator housing 16, and the sieve plate 10 is gradually inclined downward from the air separation feed port 8 to the air separation discharge port 13. A plurality of nozzles 11 are arranged on the upper side of the sieve plate 10. An air inlet 9 is arranged at the bottom of the air separator housing 16. The high-pressure fan 15 is connected to the air inlet 9. An air outlet 12 connected to a dust collection duct is arranged on the upper part of the air separator housing 16, and a maze 14 is arranged between the sieve plate 10 and the air outlet 12.

[0049] See also Figures 6-8 The strengthening equipment includes a strengthening mechanism, a conveyor 19 and a storage bin 20. The strengthening mechanism is composed of a strengthening drive motor 22, a distributor 23 and a lining plate 24. The strengthening feed port 18 is connected to the conveyor 19, the conveyor 19 is connected to the storage bin 20, and the storage bin 20 is connected to the strengthening mechanism. The strengthening drive motor 22 provides centrifugal force for the distributor 23 in the strengthening mechanism to directly eject the metal abrasive semi-finished product onto the lining plate 24 for strengthening.

[0050] The present invention is further described below in conjunction with specific examples and comparative examples. Example 4 is the best example of the present invention. The remainder in Table 1 means that all elements except the elements listed in the table are elemental Fe and impurities; "━" in Table 1 means that the element is not added.

[0051] Table 1 Composition of metal abrasives for aluminum products (by mass percentage)

[0052] .

[0053] Example 1

[0054] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0055] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650° C. for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08 wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500° C., a pouring speed of 320 kg / min, a centrifugal disc diameter of 250 mm, and a centrifuge frequency modulation range of 35 Hz to obtain a semi-finished metal abrasive;

[0056] (2) The semi-finished metal abrasive is dried, the tempering temperature is 400°C, the tempering time is 50 minutes, the cooling time is 3 minutes, the strengthening time is 0.5 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0057] Centrifugal granulation is carried out in a closed granulation pool. The molten steel obtained in step (1) is hoisted to the top of the centrifugal disk 2 in the middle area of ​​the closed granulation pool. After the molten steel is poured into the centrifugal disk 2, it is thrown out by centrifugal force. The molten steel shrinks and forms, falls into the closed granulation pool and is cooled to obtain metal abrasives specially used for semi-finished aluminum products. The granulation drive motor 7 controls the synchronous pulley 6 to move the synchronous belt 5 and the connecting frame 3, thereby driving the cover plate 4 to open and close. Closing the cover plate 4 during pouring and granulation can reduce the entry of oxygen. After the granulation is completed, the cover plate 4 is opened, and the driving crane uses an electromagnet to enter the closed granulation pool from the cover plate 4 to pick up the semi-finished metal abrasives.

[0058] The high-pressure fan 15 blows in high-pressure cold air, which enters the bottom of the air separation device through the air inlet, and then enters the upper part of the sieve plate 10 through the hole on the nozzle 11; the function of the nozzle 11 is to divide the high-pressure cold air into multiple streams and spray them out through the nozzle 11; the tempered metal abrasive semi-finished products enter through the air separation feed port 8 to exchange heat with the high-pressure cold air of the air separation device, directly contact with the high-pressure cold air, and heat transfer reduces the temperature, so that the metal abrasive semi-finished products are cooled; the metal abrasive semi-finished products are lifted up by the high-pressure cold air and present a "boiling" state, and the oxide scale in the metal abrasive semi-finished products is taken away by the wind in the "boiling" state, because the density of the oxide scale is less than that of the metal abrasive semi-finished products, and the high-pressure cold air can take away the oxide scale, thereby ensuring that the appearance color of the product is better, the color of the oxide scale is black, and the color of steel after rusting is black and yellow, and it can be judged visually whether the oxide scale is taken away by the wind of the fan.

[0059] The semi-finished metal abrasive enters from the strengthening feed port 18, passes through the conveyor 19 to the storage bin 20, and the flow rate of the storage bin 20 is adjusted. The semi-finished metal abrasive enters the divider 23 of the strengthening equipment. The semi-finished metal abrasive in the divider 23 is ejected onto the liner 24 under the action of strong centrifugal force for strengthening. The strengthened semi-finished metal abrasive falls to the conveyor 19, and is lifted to the storage bin 20 again through the conveyor 19. This cycle is repeated to complete the strengthening process.

[0060] The equipment used for centrifugal granulation, cooling and strengthening in the following examples is the same as that in Example 1.

[0061] Example 2

[0062] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0063] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650° C. for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08 wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500° C., a pouring speed of 320 kg / min, a centrifugal disc diameter of 250 mm, and a centrifuge frequency modulation range of 35 Hz to obtain a semi-finished metal abrasive;

[0064] (2) The semi-finished metal abrasive is dried, the tempering temperature is 400°C, the tempering time is 50 minutes, the cooling time is 3 minutes, the strengthening time is 1 hour, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0065] The centrifugal granulation, cooling and strengthening in this example are the same as those in Example 1.

[0066] Example 3

[0067] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0068] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650°C for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500°C, a pouring speed of 320kg / min, and a centrifuge frequency modulation range of 35Hz to obtain a semi-finished metal abrasive;

[0069] (2) The semi-finished metal abrasive is dried, the tempering temperature is 400°C, the tempering time is 50 minutes, the cooling time is 3 minutes, the strengthening time is 1.5 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0070] Example 4

[0071] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0072] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650°C for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500°C, a pouring speed of 320kg / min, and a centrifuge frequency modulation range of 35Hz to obtain a semi-finished metal abrasive;

[0073] (2) The semi-finished metal abrasive is dried, the tempering temperature is 400°C, the tempering time is 50 minutes, the cooling time is 3 minutes, the strengthening time is 2 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0074] Example 5

[0075] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0076] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650°C for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500°C, a pouring speed of 320kg / min, and a centrifuge frequency modulation range of 35Hz to obtain a semi-finished metal abrasive;

[0077] (2) The semi-finished metal abrasive is dried, the tempering temperature is 400°C, the tempering time is 50 minutes, the cooling time is 3 minutes, the strengthening time is 2.5 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0078] Example 6

[0079] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0080] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650°C for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500°C, a pouring speed of 320kg / min, and a centrifuge frequency modulation range of 35Hz to obtain a semi-finished metal abrasive;

[0081] (2) The semi-finished metal abrasive is dried, the tempering temperature is 420°C, the tempering time is 50 minutes, the cooling time is 3 minutes, the strengthening time is 1.5 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0082] Example 7

[0083] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0084] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650°C for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500°C, a pouring speed of 320kg / min, and a centrifuge frequency modulation range of 35Hz to obtain a semi-finished metal abrasive;

[0085] (2) The semi-finished metal abrasive is dried, the tempering temperature is 430°C, the tempering time is 50 min, the cooling time is 2 min, the strengthening time is 1.5 h, and the semi-finished metal abrasive is sieved to obtain a special metal abrasive for aluminum products.

[0086] Example 8

[0087] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0088] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1480° C. for 2.0 h to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08 wt% aluminum, and then centrifuged for granulation at a centrifugal granulation temperature of 1480° C., a centrifugal disk diameter of 250 mm, and a centrifuge frequency modulation range of 45 Hz to obtain a semi-finished metal abrasive;

[0089] (2) The semi-finished metal abrasive is dried, the tempering temperature is 350°C, the tempering time is 60 minutes, the cooling time is 2 minutes, the strengthening time is 1 hour, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0090] Example 9

[0091] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0092] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1660° C. for 2.0 h to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08 wt% aluminum, and then centrifuged at a centrifugal granulation temperature of 1520° C., a centrifugal disk diameter of 250 mm, and a centrifuge frequency modulation range of 22 Hz to obtain a semi-finished metal abrasive;

[0093] (2) The semi-finished metal abrasive is dried, the tempering temperature is 450°C, the tempering time is 40 minutes, the cooling time is 4 minutes, the strengthening time is 2 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0094] Example 10

[0095] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0096] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650°C for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500°C, a pouring speed of 320kg / min, and a centrifuge frequency modulation range of 35Hz to obtain a semi-finished metal abrasive;

[0097] (2) The semi-finished metal abrasive is dried, the tempering temperature is 410°C, the tempering time is 45 minutes, the cooling time is 3 minutes, the strengthening time is 2 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0098] Embodiment 11

[0099] A method for preparing a special metal abrasive for aluminum products comprises the following steps:

[0100] (1) After weighing and batching the raw materials, smelting is performed in an electric arc furnace at 1650°C for 1.5 hours to obtain molten steel; the molten steel is poured into a tundish, deoxidized by adding 0.08wt% aluminum, and then centrifuged for granulation at a pouring temperature of 1500°C, a pouring speed of 320kg / min, and a centrifuge frequency modulation range of 35Hz to obtain a semi-finished metal abrasive;

[0101] (2) The semi-finished metal abrasive is dried, the tempering temperature is 390°C, the tempering time is 55 minutes, the cooling time is 3 minutes, the strengthening time is 2 hours, and the semi-finished metal abrasive is screened to obtain a special metal abrasive for aluminum products.

[0102] Comparative Example 1

[0103] The preparation method of the special metal grinder for aluminum products described in this comparative example is the same as that in Example 4, except that water cooling is used for cooling in step (2).

[0104] Comparative Example 2

[0105] The preparation method of the special metal grinder for aluminum products described in this comparative example is the same as that in Example 4, except that step (2) is not strengthened by strengthening equipment.

[0106] Comparative Example 3

[0107] The preparation method of the special metal grinder for aluminum products described in this comparative example is the same as that in Example 4, except that the component does not contain Al.

[0108] Performance Testing

[0109] The performance of the metal abrasives prepared in the examples and comparative examples was tested, and the specific test results are shown in Table 2.

[0110] The hardness of metal abrasives specifically for aluminum products is tested in accordance with BSENISO6507-1:2023.

[0111] The proportion of spherical particles of special metal abrasives for aluminum products is tested in accordance with GB / T19816.5.

[0112] Fatigue life test: It is carried out using the Owen fatigue life machine. The specific test steps are as follows:

[0113] Weigh 100g of standard S550 shot and put it into the feeding port; seal it with a rubber stopper and set the counter to 500 times each time, then turn on the machine. After the machine runs for 500 times, open the rubber stopper and pour out all the remaining steel shots; put the remaining steel shots in a 40# (0.425mm) standard sieve for screening and vibration, weigh the remaining amount, then take the same standard shot to replenish it, and then put the machine into operation. Stop the test until the total loss is greater than or equal to 100g;

[0114] Calculate the fatigue life value of steel shot, the specific calculation formula is as follows:

[0115] Fatigue life value = total number of revolutions ⁻ (set number of revolutions / last loss amount) × (total loss amount - 100)

[0116] After calibrating the equipment, add 100g of metal abrasive and put it into the Owen fatigue life machine. The equipment starts to run, and the abrasive rotates and polishes in the equipment. After reaching the set number of rotations, the abrasive is released, sieved and weighed, and new abrasive is added to 100g, and then put into the equipment again for polishing. Repeat the cycle until the total loss reaches 100g, and the service life value is calculated according to the same formula.

[0117] Aluminum products were sprayed with the special metal abrasives for aluminum products prepared in the embodiments of the present invention and the comparative examples, with a spraying pressure of 0.4 MPa and a spraying time of 2 min; and whiteness test, blue dot test and salt spray test were performed.

[0118] 1. Whiteness test: The whiteness test of the special metal abrasive for aluminum products prepared in the examples and comparative examples was carried out using a whiteness tester model YQ-Z-48B produced by Hangzhou Qingtong Bo Ke Automation Technology Co., Ltd.

[0119] 2. Blue dot test: The blue dot test method is used to determine whether a complete passivation film is formed on the surface of the special metal abrasive for aluminum products prepared in the embodiment and the comparative example;

[0120] The specific steps are as follows:

[0121] 1. Use 1 gram of potassium ferrocyanide, add 3 ml of 65%~85% nitric acid and 100 ml of water to prepare a solution;

[0122] 2. Soak the filter paper in the solution and stick it on the surface to be tested, or directly apply or drop the solution on the surface to be tested. Observe the blue dots within 30 seconds.

[0123] 3. Salt spray test: Using the salt spray corrosion tester of Qingdao Yitai Instrument Co., Ltd., the corrosion resistance of the material in a warm, salty and humid environment was artificially simulated; the metal abrasives for aluminum products prepared in the examples and comparative examples were subjected to salt spray tests;

[0124] The specific conditions are as follows:

[0125] 1. Temperature: The temperature of the test chamber should be maintained at 35±2℃;

[0126] 2. Salt spray precipitation: Salt spray precipitation should be controlled at 1~2mL / 80cm 2 ·h, the spraying mode is continuous spraying;

[0127] 3. Test time: spray time is 12h, 24h, 36h;

[0128] 4. Salt spray pH value: brine pH = 7, brine concentration is 5% by mass concentration;

[0129] 5. Sample tilt angle: 0°.

[0130] Table 2 Performance test results of embodiments and comparative examples

[0131] .

[0132] It can be seen from Table 2 that the whiteness of the special metal abrasive for aluminum products prepared in Example 4 of the present invention can reach 88, and there are no rust spots in the salt spray test for 12h, 24h and 36h, and the blue spot test results show that there are no blue spots. The fatigue life value of the special metal abrasive for aluminum products with a particle size of 0.4mm can reach 5955. The special metal abrasive for aluminum products prepared by the present invention has no oxide layer on the surface, strong corrosion resistance, long service life, and low oxide scale content, which can make the appearance of the workpiece white and uniform.

[0133] It can be seen from the test results of comparative example 1 that the cooling without the wind selector equipment results in the oxide scale not being taken away by the fan in the "boiling" state, resulting in poor appearance color of the product and short fatigue life value. It can be seen from the test results of comparative example 2 that it is impossible to obtain a thicker compressive stress layer without strengthening by the strengthening machine equipment, and the stress corrosion resistance is poor, so there are multiple blue spots after the blue spot test; rust spots 10%, rust spots 20% and 40% appeared after 12h, 24h and 36h of salt spray test, respectively, and the fatigue life value is short; the special metal abrasive for aluminum products of the present invention has undergone a strengthening process, and there is no iron ion residue on the surface of the workpiece after sandblasting, so its anti-rust performance is good; this special metal abrasive for aluminum products can make the surface of aluminum products white and bright, and will not cause the workpiece to rust after spraying, and the price is much lower than stainless steel. It can be seen from the test results of comparative example 3 that when Al is not contained in the component, oxidation cannot be reduced, and a dense aluminum oxide film cannot be formed, which leads to reduced corrosion resistance and a short fatigue life value.

[0134] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a special metal abrasive for aluminum products, characterized in that: The following steps are involved: (1) Deoxidizing the molten steel with aluminum and then centrifugally granulating it to obtain a semi-finished metal abrasive; (2) Drying, tempering, cooling, strengthening and screening the semi-finished metal abrasive to obtain metal abrasives for aluminum products; Wherein, the cooling is performed by air cooling using air selection equipment; The air separation equipment described in step (2) comprises an air separation device housing (16), a sieve plate (10) and a high-pressure fan (15); an air separation feed port (8) and an air separation discharge port (13) are respectively provided on both sides of the air separation device housing (16); the sieve plate (10) is arranged in the air separation device housing (16); the sieve plate (10) is arranged to be gradually inclined downward in the direction from the air separation feed port (8) to the air separation discharge port (13); a plurality of nozzles (11) are provided on the upper side of the sieve plate (10); an air inlet (9) is provided at the bottom of the air separation device housing (16); the high-pressure fan (15) is connected to the air inlet (9); an air outlet (12) connected to a dust collection duct is provided at the upper part of the air separation device housing (16); a labyrinth (14) is provided between the sieve plate (10) and the air outlet (12); The maze (14) comprises a first baffle and a second baffle, the first baffle and the second baffle are arranged obliquely in opposite directions, and two ends of the second baffle are respectively located directly below two adjacent first baffles; The upper end of the nozzle (11) is closed, and a plurality of transverse ventilation holes (17) are provided on the side of the nozzle (11); The strengthening described in step (2) is carried out in a strengthening device, which includes a strengthening mechanism, a conveyor (19) and a storage bin (20); the strengthening mechanism is composed of a strengthening drive motor (22), a distributor (23) and a lining plate (24); the conveyor (19) and the storage bin (20) are connected, the storage bin (20) and the strengthening mechanism are connected, the strengthening drive motor (22) is connected to the distributor (23), the lining plate (24) and the distributor (23) are arranged opposite to each other, and the strengthening drive motor (22) provides centrifugal force for the distributor (23) in the strengthening mechanism to directly eject the metal abrasive semi-finished product onto the lining plate (24) for strengthening.

2. The method for preparing a special metal abrasive for aluminum products according to claim 1, characterized in that: The strengthening time in step (2) is 1 to 2.5 hours.

3. The method for preparing a special metal abrasive for aluminum products according to claim 1, characterized in that: The smelting temperature in step (1) is 1640-1660° C., and the smelting time is 1-2 h.

4. The method for preparing a special metal abrasive for aluminum products according to claim 1, characterized in that: The pouring temperature of the centrifugal granulation in step (1) is 1480-1520° C., and the pouring speed is 280-350 kg / min.

5. The method for preparing a special metal abrasive for aluminum products according to claim 1, characterized in that: The centrifugal granulation in step (1) is carried out in a closed granulation tank, in which a centrifugal disc (2) is provided, and a cover plate (4) is provided on the upper part of the closed granulation tank.

6. The method for preparing a special metal abrasive for aluminum products according to claim 1, characterized in that: The tempering temperature in step (2) is 350-450° C., and the tempering time is 40-60 min.

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