Method for forging crucible for 2T medium-frequency electric furnace

Abstract

The invention relates to a method for forging a crucible for a 2T medium-frequency electric furnace. The method comprises the following steps: adopting quartz sand, boric acid and water; quartz sand of different specifications is subjected to magnetic separation, and metal inclusions are prevented; uniformly mixing boric acid with quartz sand of different specifications; adding the materials into a sand mixer, and uniformly mixing; asbestos cloth is laid outside the induction coil and fixed, and the evenly-mixed furnace burden is added to the furnace bottom; placing the crucible mold in the center of the induction coil; adding the mixed crucible material between the crucible mold and the asbestos cloth; quartz sand and water glass of different specifications are selected as raw materials and are uniformly mixed to form a crucible opening; adding the material to the upper edge of the crucible; and after the crucible is placed for 12 hours, baking and sintering are carried out. According to the invention, the defects of short service life of the crucible for the 2T medium-frequency electric furnace, high cost of materials for forging the crucible, pollution to the environment in the process of forging the crucible and harm to occupational health of operators are overcome, the forging cost of the crucible is reduced, and the service life of the crucible is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of metal smelting, and particularly relates to a method for making a crucible for a 2T medium-frequency electric furnace. Background Art

[0002] The crucible of the medium frequency induction furnace works under a series of physical and chemical interweaving conditions. During the working process, it has to withstand the high temperature of about 1700℃ in the smelting process, the chemical corrosion of the slag, the impact on the crucible wall when adding raw and auxiliary materials, and the influence of rapid temperature changes during intermittent production, which can easily cause cracks in the crucible, partial detachment, etc., affecting its service life. Improving the service life of the crucible can increase the output of castings, reduce the labor intensity of workers, and reduce the comprehensive cost of castings. The one-time manufacturing cost of the crucible is also an expense. How to balance the service life and cost is the main research content of the present invention. Moreover, the traditional crucible manufacturing process and the current advanced manufacturing process are still somewhat high in complexity, and there is a certain pollution to the environment during the manufacturing process. The raw materials for manufacturing the crucible contain heavy metal elements that are harmful to the human body. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a method for making a crucible for a 2T medium frequency electric furnace to solve the above problems.

[0004] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0005] A method for making a crucible for a 2T medium frequency electric furnace, characterized in that it comprises the following steps:

[0006] S1: Select raw materials, using five kinds of quartz sand with different mesh sizes, boric acid, and water, wherein the mesh sizes of the five kinds of quartz sand are 15-20mm, 5-10mm, 3-10mm, 0.5-1mm, and 270 mesh respectively;

[0007] S2: Magnetic separation is performed on five kinds of quartz sand with different mesh sizes to prevent metal inclusions; Boric acid is sieved through a 1 mm sieve, and the H3BO3 content in the boric acid is greater than 99%, and the boric acid is evenly mixed with the five kinds of quartz sand with different mesh sizes;

[0008] S3: The weight mixing ratios of five kinds of quartz sand with mesh sizes of 15-20mm, 5-10mm, 3-10mm, 0.5-1mm and 270 mesh, boric acid and water are 25%, 15%, 10%, 13%, 30%, 2.5% and 4.5%, respectively. The above materials are added into a sand mixer, mixed evenly and discharged for standby use;

[0009] S4: Place a layer of asbestos cloth outside the induction coil and fix it, add the evenly mixed charge to the furnace bottom in 10 times, each time with a thickness of 48mm-52mm, and tamp it with a flat pneumatic pick to ensure that the tamping thickness of the furnace bottom is not less than 300mm, and form a 15° taper from the center to the edge to ensure the impact loss on the furnace bottom during the processing of raw materials;

[0010] S5: Hang the prefabricated crucible mold in the center of the induction coil. After placement, use hydraulic positioning to ensure that the thickness of the crucible wall is uniformly 100 mm;

[0011] S6: Add the mixed crucible material between the crucible mold and the asbestos cloth, each adding height is 48-52mm, use an adjustable external circular pneumatic pick to perform 5 tamping actions, the air line pressure is 0.2-0.5MPa, until the upper mouth of the crucible is flush with the medium frequency electric furnace mouth;

[0012] S7: Use the rotating unit to rotate the crucible mold clockwise, then counterclockwise, and repeat the action three times, and then the crucible mold can be taken out vertically;

[0013] S8: Making the crucible mouth, using three kinds of quartz sand and water glass with different mesh sizes, the mesh sizes of the three kinds of quartz sand are 15-20mm, 3-10mm, and 0.5-1mm respectively;

[0014] S9: three different specifications of quartz sand are mixed in weight ratios of 51%, 17%, and 17%, and 15% of water glass is added for uniform mixing and standby use;

[0015] S10: Use the mixed material to build the crucible mouth, add the material to the upper edge of the crucible, tamp it with a ramming hammer, and then smooth the iron outlet;

[0016] S11: After the prepared crucible is placed for 12 hours, it is baked and sintered;

[0017] S12: Baking time is 12 hours and can be put into use.

[0018] As a further improvement of the present invention, before the crucible is made, that is, before step S4, the induction coil of the medium frequency electric furnace is checked for deformation and protrusion to prevent the inward squeezing force on the crucible from changing the shape of the unsintered crucible.

[0019] As a further improvement of the present invention, in step S11, a medium frequency electric furnace with a power of 200 W is used for baking for 5 hours. After 5 hours, the power is increased by 60 W every half an hour, and the power is increased to 680 W in a total of 4 hours. After 4 hours, the power is increased to 800 W and baked for 1 hour. After 1 hour, the power is reduced to 300 W and baked for 2 hours.

[0020] The beneficial effects of the present invention are:

[0021] The invention solves the defects of short service life of a crucible for a 2T medium frequency electric furnace, high cost of materials for making the crucible, pollution to the environment and occupational health hazards to operators in the process of making the crucible. Boric acid is mixed with quartz sand of different specifications to reduce the sintering temperature of the crucible. Boric acid can adjust the volume change rate of the crucible. Adding boric acid can reduce the volume expansion caused by the change of quartz crystal state at the sintering temperature, thereby reducing the probability of cracks in the crucible, so that the service life of the crucible for the 2T medium frequency electric furnace is increased to 1500 times, the cost of the crucible making process is low, and the crucible making process is a wet method, so the pollution to the environment and the harm to the operator can be ignored. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail with reference to the embodiments below.

[0023] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiment of the present application will be clearly and completely described below in combination with the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0024] A method for making a crucible for a 2T medium frequency electric furnace comprises the following steps:

[0025] S1: Prepare raw materials, using quartz sand of different specifications (15-20mm, 5-10mm, 3-10mm, 0.5-1mm, 270 mesh), boric acid, and water;

[0026] S2: Magnetic separation is performed on quartz sands of different specifications to prevent metal inclusions; Boric acid (H3BO3>99%) is passed through a 1mm sieve to be evenly mixed with quartz sands of different specifications to reduce the sintering temperature of the crucible. Boric acid can also adjust the volume change rate of the crucible. Adding boric acid will reduce the volume expansion caused by the change of quartz crystal state at the sintering temperature, thereby reducing the probability of cracks in the crucible;

[0027] S3: The weight mixing ratios of five kinds of quartz sand with mesh sizes of 15-20mm, 5-10mm, 3-10mm, 0.5-1mm and 270 mesh, boric acid and water are 25%, 15%, 10%, 13%, 30%, 2.5% and 4.5%, respectively. The above materials are added into a sand mixer, mixed evenly and discharged for standby use;

[0028] S4: Before making the crucible, check whether the induction coil of the medium frequency electric furnace has any deformation bulge to prevent the inward extrusion force on the crucible, so as to change the shape of the unsintered crucible. Spread a layer of asbestos cloth outside the induction coil and fix it. Add the mixed furnace charge to the furnace bottom in 10 times, with a thickness of 48mm-52mm each time, and tamp it with a flat air pick to ensure that the ramming thickness of the furnace bottom is not less than 300mm, and form a 15° taper from the center to the edge to ensure the impact loss on the furnace bottom during the processing of raw materials;

[0029] S5: Hang the prefabricated crucible mold in the center of the induction coil. After placement, use hydraulic positioning to ensure that the thickness of the crucible wall is uniformly 100 mm;

[0030] S6: Add the mixed crucible material between the crucible mold and the asbestos cloth, each adding height is 48-52mm, use an adjustable external circular pneumatic pick to perform 5 tamping actions, the air line pressure is 0.2-0.5MPa, until the upper mouth of the crucible is flush with the medium frequency electric furnace mouth;

[0031] S7: Use the rotating unit to slowly rotate the crucible mold clockwise, and then slowly rotate it counterclockwise, and after repeating the action three times, the crucible mold can be taken out vertically;

[0032] S8: The raw materials for the crucible mouth are quartz sand (15-20mm, 3-10mm, 0.5-1mm) and water glass of different specifications;

[0033] S9: three different specifications of quartz sand are mixed in weight ratios of 51%, 17%, and 17%, and 15% of water glass is added for uniform mixing and standby use;

[0034] S10: Use the mixed material to build the crucible mouth, add the material to the upper edge of the crucible, tamp it with a ramming hammer, and then smooth the iron outlet;

[0035] S11: After the prepared crucible is placed for 12 hours, it is baked and sintered;

[0036] S12: The baking time is 12 hours before it can be put into use, wherein, a medium frequency electric furnace with a power of 200W is used for baking for 5 hours. After 5 hours, the power is increased by 60W every half an hour, and the power is increased to 680W in a total of 4 hours. After 4 hours, the power is increased to 800W and baked for 1 hour. After 1 hour, the power is reduced to 300W and baked for 2 hours.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for making a crucible for a 2T medium frequency electric furnace, characterized in that: The following steps are involved: S1: Select raw materials, using five kinds of quartz sand with different mesh sizes, boric acid, and water, wherein the mesh sizes of the five kinds of quartz sand are 15-20mm, 5-10mm, 3-10mm, 0.5-1mm, and 270 mesh respectively; S2: Magnetic separation is performed on five kinds of quartz sand with different mesh sizes to prevent metal inclusions; Boric acid is sieved through a 1 mm sieve, and the H3BO3 content in the boric acid is greater than 99%, and the boric acid is evenly mixed with the five kinds of quartz sand with different mesh sizes; S3: The weight mixing ratios of five kinds of quartz sand with mesh sizes of 15-20mm, 5-10mm, 3-10mm, 0.5-1mm and 270 mesh, boric acid and water are 25%, 15%, 10%, 13%, 30%, 2.5% and 4.5%, respectively. The above materials are added into a sand mixer, mixed evenly and discharged for standby use; S4: Place a layer of asbestos cloth outside the induction coil and fix it, add the evenly mixed charge to the furnace bottom in 10 times, each time with a thickness of 48mm-52mm, and tamp it with a flat pneumatic pick to ensure that the tamping thickness of the furnace bottom is not less than 300mm, and form a 15° taper from the center to the edge to ensure the impact loss on the furnace bottom during the processing of raw materials; S5: Hang the prefabricated crucible mold in the center of the induction coil. After placement, use hydraulic positioning to ensure that the thickness of the crucible wall is uniformly 100 mm; S6: Add the mixed crucible material between the crucible mold and the asbestos cloth, each adding height is 48-52mm, use an adjustable external circular pneumatic pick to perform 5 tamping actions, the air line pressure is 0.2-0.5MPa, until the upper mouth of the crucible is flush with the medium frequency electric furnace mouth; S7: Use the rotating unit to rotate the crucible mold clockwise, then counterclockwise, and repeat the action three times, and then the crucible mold can be taken out vertically; S8: Making the crucible mouth, using three kinds of quartz sand and water glass with different mesh sizes, the mesh sizes of the three kinds of quartz sand are 15-20mm, 3-10mm, and 0.5-1mm respectively; S9: three different specifications of quartz sand are mixed in weight ratios of 51%, 17%, and 17%, and 15% of water glass is added for uniform mixing and standby use; S10: Use the mixed material to build the crucible mouth, add the material to the upper edge of the crucible, tamp it with a ramming hammer, and then smooth the iron outlet; S11: After the prepared crucible is placed for 12 hours, it is baked and sintered; S12: Baking time is 12 hours and can be put into use.

2. The method for making a 2T medium frequency electric furnace crucible according to claim 1, characterized in that: Before making the crucible, that is, before step S4, check whether the induction coil of the medium frequency electric furnace has any deformed protrusions to prevent the inward squeezing force on the crucible from changing the shape of the unsintered crucible.

3. The method for making a 2T medium frequency electric furnace crucible according to claim 1, characterized in that: In step S11, a medium frequency electric furnace with a power of 200W is used for baking for 5 hours. After 5 hours, the power is increased by 60W every half an hour, and the power is increased to 680W in a total of 4 hours. After 4 hours, the power is increased to 800W and baked for 1 hour. After 1 hour, the power is reduced to 300W and baked for 2 hours.