A method for making a floor sand core containing chromite sand

Abstract

The application relates to a method for manufacturing a bottom plate core containing chromic iron ore sand, which comprises the following steps: S1, laying a foamed template which is consistent with the shape of one side of a bottom plate to be cast in the area of the finished product of the bottom plate; S2, forming a partition cavity between adjacent rib plates of the foamed template, filling quartz sand in the partition cavity, laying a first layer of chromic iron ore sand on the surface of the quartz sand, and forming the surface of the finished product of the cast bottom plate on the surface of the first layer of chromic iron ore sand; S3, installing a cylinder on the upper surface of the first layer of chromic iron ore sand, which is used for forming a sink of the finished product of the bottom plate, the cylinder is formed by compactly filling quartz sand, and a second layer of chromic iron ore sand is laid on the outer surface of the cylinder; S4, removing the foamed template, and laying a third layer of chromic iron ore sand on the wall surface of the concave cavity formed after the foamed template is removed; and S5, forming the finished product of the bottom plate after casting molten steel on the surface of the first layer of chromic iron ore sand and in the concave cavity. The application greatly reduces the cost of sand materials under the premise of ensuring the forming quality of the surface of the castings.

Description

Technical Field

[0001] This invention relates to the field of casting core making technology, specifically to a method for making a base plate core containing chromite sand. Background Technology

[0002] In the casting production of base plate castings (used in bridge abutments), corresponding cores are required to form the internal structure and molding surface of the casting. Currently, the cavity filling process for existing base plate cores generally uses chromite sand throughout the entire process. Chromite sand has a melting point of over 2000℃, while the temperature of molten iron used in casting is approximately 1800℃. Therefore, chromite sand will not melt and adhere when in direct contact with molten iron, ensuring a smooth casting surface, free of sand adhesion defects, and stable molding quality. However, the material cost of chromite sand is relatively high, approximately 2000-3000 yuan per ton, significantly increasing the cost of core production.

[0003] In comparison, the cost of quartz sand is only 200-300 yuan per ton, about one-tenth of that of chromite sand, giving it a significant cost advantage. However, quartz sand has a melting point of about 1800℃, which is close to the temperature of molten iron. If quartz sand comes into direct contact with high-temperature molten iron, it will partially melt and adhere to the surface of the casting, resulting in sand adhesion and excessive roughness on the casting surface, affecting the quality of the finished product. Therefore, quartz sand cannot directly replace chromite sand as a contact surface material.

[0004] Furthermore, when constructing cylindrical structures for settling tanks on existing base cores, prefabricated components made from chromite sand are commonly used. This process requires first excavating a circular settling tank on the surface of the chromite sand layer in the core, then inserting the prefabricated chromite sand cylinder into the tank for fixation. This method is cumbersome, involves numerous steps in prefabrication and on-site installation, and results in low overall production efficiency, hindering production improvement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for making a bottom plate core containing chromite sand, which can significantly reduce the cost of sand while ensuring the surface forming quality of the casting.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a base plate core containing chromite sand, comprising the following steps: Step S1: Laying a foam template that matches the shape of one side of the base plate in the area of ​​the finished base plate to be cast; Step S2: Forming a cavity between adjacent stiffeners of the foam template, filling the cavity with quartz sand, applying a first layer of chromite sand on the surface of the quartz sand, and forming the surface of the finished base plate on the surface of the first layer of chromite sand; Step S3: Installing a cylinder on the upper surface of the first layer of chromite sand to form a settling groove for the finished base plate, the cylinder being densely filled with quartz sand, and applying a second layer of chromite sand on the outer surface of the cylinder; Step S4: Removing the foam template, and applying a third layer of chromite sand to the wall of the cavity formed after removing the foam template; Step S5: Pouring molten steel on the surface of the first layer of chromite sand and in the cavity to form the finished base plate.

[0007] Further, the fabrication and installation of the cylinder in step S3 specifically includes the following sub-steps: S31, First, draw lines on the upper surface of the first chromite sand layer. These lines include horizontal and vertical lines, and the intersection of the horizontal and vertical lines is the center position for cylinder installation; S32, After using a pair of cylindrical mold parts to fit together and tighten, a cylindrical cavity is formed. Four alignment lines parallel to the center line of the cylindrical cavity are drawn on the side wall of the cylindrical mold parts. The four alignment lines are offset by 90 degrees in the circumferential direction. After the four alignment lines are aligned with the horizontal and vertical lines in pairs, the cylindrical cavity is filled with quartz sand; S33, Insert at least one steel bar into the dense quartz sand of the cylinder. The steel bar extends to the bottom of the cavity, and the upper end of the steel bar does not protrude from the upper surface of the cylinder; S34, Remove the fitted cylindrical mold parts to form the quartz sand cylinder.

[0008] Furthermore, the cylindrical mold body is rectangular in shape, with a semi-cylindrical concave surface on one side surface. When the semi-cylindrical concave surfaces of the two cylindrical mold bodies are aligned and joined together, a cylindrical cavity is formed.

[0009] Furthermore, after the two cylindrical mold parts are assembled, two buckle plates are fastened to their outer sides. The buckle plates are rectangular in shape and have rectangular grooves. The rectangular grooves are fastened to the outer wall surface of the assembled two cylindrical mold parts, thereby achieving the assembly and fastening of the two cylindrical mold parts.

[0010] Furthermore, in step S2, after filling the cavity with quartz sand, it is necessary to first level it. When leveling, a first scraper is used. The first scraper has a first lower boss in the middle. The lower edges of both sides of the first scraper are supported on the upper surface of the foam template. The lower surface of the first lower boss matches the surface of the quartz sand in the cavity.

[0011] Furthermore, in step S2, after laying the first chromite sand layer, it is necessary to level it. A second scraper is used for leveling. The second scraper has a second lower boss in the middle. The lower edges of both sides of the second scraper are supported on the upper surface of the foam template. The lower surface of the second lower boss matches the surface of the first chromite sand layer. The height difference between the lower surface of the first lower boss and the lower edges of both sides of the first scraper is H1, and the height difference between the lower surface of the second lower boss and the lower edges of both sides of the second scraper is H2. H1-H2 = the thickness of the first chromite sand layer.

[0012] Furthermore, the thickness of the first, second, and third chromium-bearing iron ore sand layers is 2-3 cm.

[0013] Compared with the prior art, the present invention has the following advantages: 1. The present invention uses low-cost quartz sand to fill the main filling area of ​​the cavity, and only applies a 2-3 cm thick layer of chromium iron ore sand on the surface that is in direct contact with molten iron. This not only utilizes the high melting point of chromium iron ore sand to ensure that the casting surface is free of sand and the forming quality is stable, but also significantly reduces the cost of sand by replacing a large amount of it with quartz sand, resulting in significant economic benefits.

[0014] 2. This invention eliminates the need for prefabricating chromite sand cylindrical precast components. Instead, it directly produces quartz sand cylinders on-site by assembling cylindrical molds, filling with quartz sand, and demolding. A chromite sand layer is then applied to the outer surface. This eliminates the cumbersome processes of precast component production and trenching installation, resulting in a simpler production process, significantly improved production efficiency, and suitability for mass production applications.

[0015] 3. By inserting steel bars into the quartz sand cylinder and extending them to the bottom of the cavity, the cylindrical structure can be reinforced to prevent sand displacement and collapse during casting, thus ensuring the accuracy of the settling tank. At the same time, by using a special scraper to scrape the quartz sand and chromite sand layers in layers, the thickness of the sand layer can be precisely controlled to ensure the flatness and dimensional consistency of the forming surface. Attached Figure Description

[0016] Figure 1 is a top view of the foam template in an embodiment of the present invention; Figure 2 is a top view of the structure after the casting core is formed in an embodiment of the present invention; Figure 3 is a schematic diagram of the cross-sectional structure of the cavity according to an embodiment of the present invention; Figure 4 is a schematic cross-sectional view of the upper surface of the first chromium-containing iron ore sand layer scraped by the second scraper in an embodiment of the present invention. Figure 5 is a schematic diagram of the structure of the first scraper in an embodiment of the present invention; Figure 6 is a schematic diagram of the structure of the second scraper in an embodiment of the present invention; Figure 7 is a schematic cross-sectional view of the structure after the cylinder is installed in an embodiment of the present invention; Figure 8 is a schematic cross-sectional view of the structure after the foam template is removed in an embodiment of the present invention; Figure 9 is a schematic diagram of the exploded structure of the cylindrical mold and the snap-on plate in an embodiment of the present invention; Figure 10 is a schematic diagram of the cylindrical mold closing and snap-fit ​​structure in an embodiment of the present invention; Figure 11 is Figure 10 A schematic diagram of the structure viewed from below; Figure 12 is Figure 10 A schematic diagram of the left-side view structure; In the diagram: 1. Foam template, 2. Cavity, 3. Quartz sand, 4. First chromite sand layer, 5. Cylinder, 6. Second chromite sand layer, 7. Concave cavity, 8. Third chromite sand layer, 9. Columnar mold, 10. Alignment line, 11. Reinforcing bar, 12. Buckle plate, 13. First scraper, 14. First lower boss, 15. Second scraper, 16. Second lower boss. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0019] As shown in Figures 1 and 4, this embodiment discloses a method for preparing a base plate core containing chromite sand, used for preparing a casting core for a base plate casting, specifically including the following steps: Step S1: Laying foam template: In the forming area of ​​the finished base plate to be cast, foam template 1 is laid in advance. The shape of foam template 1 is completely consistent with the shape of one side of the base plate to be formed, serving as the reference for sand filling and side enclosure (or it can be called the sand filling mold).

[0020] Step S2: Filling the cavity and applying a surface layer of chromite sand: A cavity 2 is naturally formed between adjacent reinforcing plates of the foam template 1. Quartz sand 3 is first filled into the cavity 2. After filling to the set height, the surface of the quartz sand 3 is smoothed using the first scraper 13. The first scraper 13 has a first lower boss 14 integrally provided in the middle. The lower edges on both sides of the first scraper 13 are support edges. When smoothing, the support edges rest on the upper surface of the foam template 1. The lower surface of the first lower boss 14 is in contact with the upper surface of the quartz sand 3 in the cavity 2. By moving the first scraper 13 along the foam template 1, the quartz sand 3 in the cavity 2 can be smoothed (the upper surface of the quartz sand 3 can be a flat or curved surface, and the lower surface of the first lower boss 14 is correspondingly a flat or curved surface), and the height of the quartz sand layer is kept consistent.

[0021] After the quartz sand layer is leveled, a first chromite sand layer 4 is evenly laid on its surface, with the thickness of the first chromite sand layer 4 controlled to be 2-3 cm. After laying, a second scraper 15 is used to level the first chromite sand layer 4. A second lower boss 16 is integrally provided in the middle of the second scraper 15, and the lower edges on both sides of the second scraper 15 also rest on the upper surface of the foam template 1. The lower surface of the second lower boss 16 is in contact with the surface of the first chromite sand layer 4.

[0022] The height difference between the lower surface of the first lower boss 14 and the lower edges of both sides of the first scraper 13 is H1, and the height difference between the lower surface of the second lower boss 16 and the lower edges of both sides of the second scraper 15 is H2. The difference between H1 and H2 is exactly equal to the design thickness of the first chromite sand layer 4, thus ensuring precise control of the sand layer thickness. The upper surface of the first chromite sand layer 4 after being scraped flat is the forming surface of the finished casting base plate.

[0023] Step S3: Fabrication of the settling tank cylinder: A cylinder 5 is fabricated on the upper surface of the first chromite sand layer 4. This cylinder 5 is used to form the settling tank structure on the finished base plate after casting. The main body of the cylinder 5 is densely filled with quartz sand 3. After fabrication, a second chromite sand layer 6 is evenly applied to the outer surface of the cylinder 5. The thickness of the second chromite sand layer 6 is also 2-3 cm to prevent the quartz sand from directly contacting the molten iron.

[0024] The specific manufacturing and installation steps of cylinder 5 are as follows: S31, Marking and positioning: First, mark lines on the upper surface of the first chromite sand layer 4. The markings include mutually perpendicular horizontal and vertical lines. The intersection of the horizontal and vertical lines is the center position for the installation of cylinder 5 (this intersection is also the center of the circular sink in the base plate drawing), ensuring accurate positioning. S32, Mold assembly and sand filling: Use a pair of identical cylindrical mold parts 9. The cylindrical mold parts 9 are generally rectangular, and one side of their surface is machined with a semi-cylindrical concave surface. Align the semi-cylindrical concave surfaces of the two cylindrical mold parts 9 together to form a complete cylindrical cavity. Alignment lines 10 are drawn on the outer wall of each cylindrical mold segment 9. These alignment lines 10 are parallel to the center line of the cylindrical cavity, and are staggered by 90 degrees in the circumferential direction (the four alignment lines 10 are located at the center of the four walls of the cuboid-shaped mold assembly, and are perpendicular to the bottom surface of the mold assembly). The assembled cylindrical mold segments 9 are placed at the marked positions, aligning the four alignment lines 10 with the corresponding horizontal and vertical lines. After positioning, quartz sand 3 is filled into the cylindrical cavity and compacted. To ensure a tight fit, two snap-fit ​​plates 12 are placed on the outer sides of the assembled two cylindrical mold segments 9. The snap-on plate 12 is rectangular in shape, and a rectangular groove is provided on the snap-on plate 12. The width of the rectangular groove is adapted to the total width of the outer wall of the two cylindrical mold parts 9 after they are joined (or the rectangular groove is tightly fitted to the outer wall of the joined cylindrical mold). By snapping the rectangular groove onto the outer wall surface after joining from the outside to the inside, the two cylindrical mold parts 9 can be prevented from separating outward, ensuring the stability of the cavity shape. S33, Inserting reinforcing steel bars: Insert at least one steel bar 11 into the filled and compacted quartz sand cylinder. The steel bar 11 is inserted downward and extends to the bottom of the cavity 2, and the upper end of the steel bar 11 does not protrude from the upper surface of the cylinder 5. The steel bar 11 can play a skeletal reinforcement role for the quartz sand cylinder, preventing the sand from shifting or collapsing due to the impact of molten iron during the casting process, and ensuring the forming accuracy of the settling tank. S34. Demolding and molding: After the quartz sand is filled and compacted, first remove the two outer buckle plates 12, then separate and remove the two cylindrical mold parts 9, so that a complete quartz sand cylinder 5 can be formed on the first chromite sand layer 4 (as mentioned above, the second chromite sand layer 6 needs to be evenly applied to the outer surface of the cylinder 5).

[0025] Step S4: Remove the foam template and lay the side chromite sand layer: After the sand body and cylinder 5 in cavity 2 are completed, remove the pre-laid foam template 1. After the foam template 1 is removed, a concave cavity 7 will be formed on the side of the adjacent sand body. A third chromite sand layer 8 is evenly laid on the inner wall surface of the concave cavity 7. The thickness of the third chromite sand layer 8 can be 2-3 cm or 1-2 cm, so that the inner wall of the concave cavity 7 is completely covered with chromite sand, avoiding direct contact between the internal quartz sand and molten iron.

[0026] Step S5, Casting and Molding: After the clay core is made, molten steel is poured into the top of the first chromite sand layer 4 and into the cavity 7. After cooling, a finished base plate with a smooth surface and no sand adhesion defects can be obtained.

[0027] The manufacturing method of this embodiment, through the structure of filling the main body with quartz sand and covering the surface with chromium iron ore sand, significantly reduces the cost of sand while ensuring the quality of casting. At the same time, the method of making quartz sand cylinders on-site by mold assembly replaces the traditional prefabrication process, simplifies the process, improves production efficiency, and is suitable for the mass casting production of base plate castings.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for preparing a substrate core containing chromite sand, characterized in that, Step S1: Lay a foam template that matches the shape of one side of the base plate in the finished product area to be cast; Step S2: A cavity is formed between adjacent stiffeners of the foam template, and the cavity is filled with quartz sand. A first layer of chromite sand is laid on the surface of the quartz sand, and the surface of the cast base plate is formed on the surface of the first layer of chromite sand. Step S3: Install a cylinder on the upper surface of the first chromite sand layer to form a settling tank for the finished bottom plate. The cylinder is formed by densely filling with quartz sand. A second chromite sand layer is laid on the outer surface of the cylinder. Step S4: Remove the foam template and lay a third layer of chromium iron ore sand on the wall surface of the cavity formed after removing the foam template. Step S5: After pouring molten steel into the cavity on the surface of the first chromite sand layer, the finished base plate is formed.

2. The method for preparing the bottom plate core of chromite sand according to claim 1, characterized in that, Step S3: Cylinder fabrication and installation steps: S31. First, draw lines on the upper surface of the first chromite sand layer. These lines include horizontal and vertical lines. The intersection of the horizontal and vertical lines is the center position for cylinder installation. S32. After using a pair of cylindrical mold parts to fit together and tighten, a cylindrical cavity is formed. Four alignment lines parallel to the center line of the cylindrical cavity are drawn on the side wall of the cylindrical mold parts. The four alignment lines are offset by 90 degrees in the circumferential direction. After aligning the four alignment lines with the horizontal and vertical lines in pairs, the cylindrical cavity is filled with quartz sand. S33. Insert at least one steel bar into the dense quartz sand of the cylinder. The steel bar extends to the bottom of the cavity, and the upper end of the steel bar does not protrude from the upper surface of the cylinder. S34. Remove the fitted cylindrical mold parts to form the quartz sand cylinder.

3. The method for preparing the bottom plate core of chromite sand according to claim 2, characterized in that, The cylindrical mold is rectangular in shape, with a semi-cylindrical concave surface on one side. When the semi-cylindrical concave surfaces of two cylindrical molds are aligned and joined together, a cylindrical cavity is formed.

4. The method for preparing the bottom plate core of chromite sand according to claim 3, characterized in that, After the two cylindrical molds are assembled, two buckle plates are fastened to their outer sides. The buckle plates are rectangular in shape and have rectangular grooves. The rectangular grooves are fastened to the outer wall surface of the assembled two cylindrical molds.

5. The method for preparing the bottom plate core of chromite sand according to claim 1, characterized in that, In step S2, after filling the cavity with quartz sand, it is necessary to scrape it flat. When scraping, a first scraper is used. The first scraper has a first lower boss in the middle. The lower edges of both sides of the first scraper are supported on the upper surface of the foam template. The lower surface of the first lower boss matches the surface of the quartz sand in the cavity.

6. The method for preparing the bottom plate core of chromite sand according to claim 5, characterized in that, In step S2, after laying the first chromite sand layer, it needs to be leveled. A second scraper is used for leveling. The second scraper has a second lower boss in the middle. The lower edges of both sides of the second scraper are supported on the upper surface of the foam template. The lower surface of the second lower boss matches the surface of the first chromite sand layer. The height difference between the lower surface of the first lower boss and the lower edges of both sides of the first scraper is H1, and the height difference between the lower surface of the second lower boss and the lower edges of both sides of the second scraper is H2. H1-H2=thickness of the first chromite sand layer.

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