Casting method for solving non-forming problem of one-box multi-piece pouring of lost foam
By combining a paper tube gating system and a ceramic tube direct sprue, the problem of casting non-formation caused by the collapse of the gating cup sand in lost foam casting was solved, achieving high-quality casting and processing, and reducing production costs.
Patent Information
- Application Number
- CN202510944046.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2025-11-14
AI Technical Summary
In lost foam casting, the molding sand in the pouring cup is prone to collapse, which can clog the filter and prevent molten iron from entering the mold cavity, resulting in problems such as incomplete casting and sand or paint flushing.
A paper tube casting system is adopted, which combines a ceramic tube sprue with a rectangular sleeve to concentrate pressure for casting, ensuring complete filling of the mold with molten iron. A negative pressure device is used to expel gas from the mold cavity to avoid uneven pressure. The pouring cup is protected by alcohol-based coating and refractory bricks.
It solved the problems of casting non-formation and machining abnormalities, improved the internal quality of castings and machining efficiency, and reduced production costs.
Smart Images
Figure CN120940583A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lost foam casting, and more particularly to a casting method for solving the problem of multiple parts failing to form a complete shape when poured in a lost foam casting mold. Background Technology
[0002] During the casting process, the paper tube gating system often uses resin sand to make the pouring cup. Due to the long-term impact of molten iron, the molding sand inside the pouring cup is prone to disintegration, and a large amount of coating falls off and enters the pouring filter, causing filter blockage and insufficient filling, resulting in the scrapping of the casting. At the same time, the coating and molding sand inside the pouring cup are flushed into the gating system and eventually into the casting, resulting in sand inclusions on the bottom surface of the casting during processing, increasing tool wear, and seriously affecting processing efficiency.
[0003] To address the problems existing in the current technology, in lost foam casting, a large amount of EPS foam vaporizes after the molten iron enters the mold cavity. Upon entering the paper tube gating system, this vaporization of EPS foam generates a large amount of gas. Under pressure, the molten iron cannot enter the mold cavity, resulting in the casting failing to form. Therefore, it is necessary to solve problems such as casting failure, sand flushing, coating flushing, and difficulty in machining. Summary of the Invention
[0004] In view of this, the purpose of this invention is to propose a casting method that solves the problem of multiple parts failing to form in a single casting mold in lost foam casting, thus solving the problems in the background art.
[0005] To achieve the above objectives, the present invention provides a casting method for solving the problem of multiple parts failing to form in a single casting mold using a lost foam casting process, comprising the following steps: Step 1: Place the foam model at the bottom of the sand box and set up the paper tube gating system. The paper tube gating system is connected to the sprue with the same diameter. The sprue is made of ceramic tube and the paper tube gating system is connected to the ingate. The ingate is connected to the foam model. Step 2: Make a rectangular base with 8 round openings of the same size as the sprue opening. Insert the sprue of the ceramic tube into the round openings of the base. Step 3: Embed the sand and compact it while embedding the sand, ensuring that the distance between the straight pouring channels of the ceramic pipe is 15-20mm. After the sand is embedded, cover it with a metal mesh and fix the sand box with clips. Wait for the molding sand to cure and gain strength. Turn the box over after 5-6 hours. Step 4: After the shaping is completed, turn the base over. After turning it over, set a rectangular sleeve on the base. The rectangular sleeve gathers the round opening of the base into a space. Clean the loose sand on the base. Then place the second metal mesh. The second metal mesh has a square hole at the rectangular sleeve. Then bury sand to shape it, tamping it down as you bury the sand. Step 5: After the bottom sand is buried, place a rectangular sleeve on the second metal mesh. The rectangular sleeve is connected to the rectangular sleeve below the second metal mesh with tape. Then, place the cast iron pouring cup on the second metal mesh, with the rectangular sleeve below the cast iron pouring cup. Then, bury the sand and shape it, tamping it down as you bury the sand. Finally, lay refractory bricks inside the pouring cup. Step 6: After complete curing, hoist the vessel to the pouring area. After 2-3 hours, clean the floating sand inside the pouring cup and rectangular sleeve with a vacuum cleaner. Apply alcohol-based coating to the inside of the pouring cup with a coating thickness of about 2mm. Then, ignite the vessel to dry the alcohol-based coating. Step 7: Pouring. During pouring, the ladle nozzle is aligned with the rectangular sleeve and the molten iron is poured in. The molten iron quickly fills the rectangular sleeve. The sprue of the independent ceramic tube corresponding to the rectangular sleeve can be lifted into the molten iron. Since the molten iron in the rectangular sleeve is always kept full, the filling pressure is high. Step 8: After casting is completed, the temperature of the casting in the sand box is measured and recorded using the thermocouples attached during molding. When the temperature drops to about 350℃, the sand is removed and the casting is lifted out. After cooling to room temperature, the gating system and slag removal system are removed, the surface is polished, and the casting is inspected and put into storage.
[0006] Preferably, the diameter of both the paper tube gating system and the direct gating system in step one is φ70mm.
[0007] Preferably, the rectangular base in step two has dimensions of 435*245*35mm and a round opening diameter of φ70mm; the rectangular sleeves in steps four and five have a height of 300mm.
[0008] Preferably, the resin addition ratio in the molding sand of the three and four steps of the molding operation is 1.0%, ensuring that the molding sand strength is greater than 1.5 MPa.
[0009] Preferably, the resin addition ratio in the molding sand of step five, the sand embedding and molding operation, is 1.0%, ensuring that the molding sand strength is greater than 2.2 MPa. Preferably, in step five, the edge of the rectangular sleeve on the metal mesh is 30-50mm higher than the refractory brick.
[0010] Preferably, in step six, after drying the alcohol-based coating and before pouring, a pressure iron is placed on the surface of the sand box. The weight of the pressure iron is 7 times the weight of the pouring weight to resist the pressure of the molten iron pouring and the pressure formed after the foam vaporization. At the same time, a negative pressure pipe is connected to start the negative pressure equipment to reduce the pressure in the sand box and allow the gas in the cavity to be discharged quickly.
[0011] The beneficial effects of this invention are as follows: The paper tube of the paper tube casting system of this invention is connected to the sprue of the ceramic tube. The sprue of the independent ceramic tube is concentrated in the rectangular sleeve. The pressure is concentrated during casting. Due to the concentrated pressure, the independent sprue in the pouring cup can supply molten iron at the same time. This solves the problem of small independent castings in a casting system not forming due to insufficient pressure caused by the large cross-sectional area of the pouring cup. At the same time, it solves the casting abnormalities such as slag inclusions and sand erosion that occur during processing, greatly improving the internal quality of the castings and increasing customer satisfaction. Attached Figure Description
[0012] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0013] Figure 1 This is a schematic diagram of the invention before it is turned over; Figure 2 This is a schematic diagram of the invention after it has been flipped over; Figure 3 This is a schematic diagram of the foam model connecting the paper tube casting system of the present invention.
[0014] The diagram is marked as follows: 1-Paper tube sprue, 2-Sprue, 3-Ingate, 4-Foam model, 5-Base, 6-Metal mesh one, 7-Sand box, 8-Rectangular sleeve, 9-Metal mesh two, 10-Sprue cup. Detailed Implementation
[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.
[0016] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0017] like Figures 1 to 3 As shown, this embodiment provides a casting method for solving the problem of multiple parts failing to form in a lost foam casting process, including the following steps: S1. Place the foam model inside the sand box 7 at the bottom and set up a paper tube gating system. The paper tube gating system's paper tube gating channel 1 is connected to its sprue 2 with the same diameter. The sprue 2 is made of ceramic tube. The paper tube gating channel is connected to the ingate 3. The ingate 3 is connected to the foam model 4. The diameter of both the paper tube gating channel and the sprue is φ70mm to avoid paper tube breakage caused by incomplete filling of the mold with molten iron in the gating channel. S2. Make a rectangular base 5. The base 5 has 8 round openings with the same size as the sprue opening. Insert the sprue 2 of the ceramic tube into the round openings of the base 5. The rectangular base 5 has dimensions of 435*245*35mm and a round opening diameter of φ70mm. The main purpose of the rectangle is to reduce the amount of sand swallowed between the base and the model and the metal sand box, thereby reducing production costs. S3, carry out sand embedding molding. The resin addition ratio in the molding sand for sand embedding molding operation is 1.0%, ensuring that the molding sand strength is greater than 1.5MPa. While embedding the sand, tamp it down to ensure that the distance between the straight pouring channels 2 of the ceramic pipe is 20mm. After the sand embedding is completed, cover it with metal mesh 6, fix the sand box 7 with clips and wait for the molding sand to cure and gain strength. Turn the box over after 6 hours. S4. After the molding surface is completed, the mold is turned over. After turning over, a rectangular sleeve 8 is set on the base 5. The height of the rectangular sleeve 8 is 300mm. The rectangular sleeve gathers the round opening of the base 5 into a space. The floating sand on the base 5 is cleaned. Then, a second metal mesh 9 is placed. The second metal mesh 9 has a square hole at the rectangular sleeve 8. Then, the sand is buried and molded. The resin addition ratio in the molding sand of the sand burying and molding operation is 1.0%, ensuring that the molding sand strength is greater than 1.5MPa. The sand is buried and compacted at the same time. S5. After the bottom sand is buried, place a rectangular sleeve 8 on the metal mesh 2 9. The height of the rectangular sleeve 8 is 300mm. The rectangular sleeve 8 is connected to the rectangular sleeve 8 below the metal mesh 2 9 by tape. Then, place the cast iron pouring cup 10 on the metal mesh 2 9. The rectangular sleeve is located below the cast iron pouring cup. Then, sand burying molding is performed. The resin addition ratio in the molding sand of the sand burying molding operation is 1.0% to ensure that the molding sand strength is greater than 2.2MPa. The sand is buried and compacted at the same time. Then, refractory bricks are laid in the pouring cup 10. The edge of the rectangular sleeve 8 is 50mm higher than the refractory bricks to prevent impurities in the molding sand and molten iron from entering the rectangular sleeve during pouring. S6, after complete curing, is hoisted to the pouring area. After 3 hours, the floating sand inside the pouring cup 10 and rectangular sleeve 8 is cleaned with a vacuum cleaner. The inside of the pouring cup 10 is coated with alcohol-based paint with a thickness of about 2mm. The alcohol-based paint is then dried by ignition. S7. After drying the alcohol-based coating, place a pressure iron on the surface of the sand box before pouring. The weight of the pressure iron is 7 times the weight of the pouring weight to resist the pressure of pouring molten iron and the pressure formed after foam vaporization. At the same time, connect the negative pressure pipe and turn on the negative pressure equipment to reduce the pressure in the sand box and allow the gas in the cavity to be discharged quickly. S8, pouring is carried out. During pouring, the ladle nozzle is aligned with the rectangular sleeve 8 and the molten iron is poured in. The molten iron quickly fills the rectangular sleeve. The sprue 2 of the independent ceramic tube corresponding to the rectangular sleeve 8 can be lifted into the molten iron. Since the molten iron in the rectangular sleeve 8 is always full, the filling pressure is high. This avoids direct contact between the molten iron and the refractory bricks in the pouring cup. At this time, the resin sand and refractory bricks in the pouring cup play an auxiliary role to prevent the molten iron from leaking out. S8. After casting is completed, the temperature of the casting in the sand box is measured and recorded by the thermocouple attached during molding. When the temperature drops to about 350℃, the sand is removed and the casting is lifted out. After cooling to room temperature, the gating system and slag removal system are removed, the surface is polished and smoothed, and the casting is inspected and put into storage.
[0018] By concentrating the independent sprues within the same base and rectangular sleeve, the problem of insufficient filling in castings connected to some paper tube sprues due to uneven pressure in the pouring cup is avoided. The sprue occupies little space, saving production costs, ensuring its filling speed and pressure, and improving the machining quality of the casting's bottom surface, thus effectively guaranteeing the quality of the casting.
[0019] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and many other variations of different aspects of the invention as described above exist, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.
Claims
1. A casting method for solving the problem of multiple parts failing to form a shape in a lost foam casting process, characterized in that, It includes the following steps: Step 1: Place the foam model at the bottom of the sand box and set up the paper tube gating system. The paper tube gating system is connected to the sprue with the same diameter. The sprue is made of ceramic tube and the paper tube gating system is connected to the ingate. The ingate is connected to the foam model. Step 2: Make a rectangular base with 8 round openings of the same size as the sprue opening. Insert the sprue of the ceramic tube into the round openings of the base. Step 3: Embed the sand and compact it while embedding the sand, ensuring that the distance between the straight pouring channels of the ceramic pipe is 15-20mm. After the sand is embedded, cover it with a metal mesh and fix the sand box with clips. Wait for the molding sand to cure and gain strength. Turn the box over after 5-6 hours. Step 4: After the shaping is completed, turn the base over. After turning it over, set a rectangular sleeve on the base. The rectangular sleeve gathers the round opening of the base into a space. Clean the loose sand on the base. Then place the second metal mesh. The second metal mesh has a square hole at the rectangular sleeve. Then bury sand to shape it, tamping it down as you bury the sand. Step 5: After the bottom sand is buried, place a rectangular sleeve on the second metal mesh. The rectangular sleeve is connected to the rectangular sleeve below the second metal mesh with tape. Then, place the cast iron pouring cup on the second metal mesh, with the rectangular sleeve below the cast iron pouring cup. Then, bury the sand and shape it, tamping it down as you bury the sand. Finally, lay refractory bricks inside the pouring cup. Step 6: After complete curing, hoist the vessel to the pouring area. After 2-3 hours, clean the floating sand inside the pouring cup and rectangular sleeve with a vacuum cleaner. Apply alcohol-based coating to the inside of the pouring cup with a coating thickness of about 2mm. Then, ignite the vessel to dry the alcohol-based coating. Step 7: Pouring. During pouring, the ladle nozzle is aligned with the rectangular sleeve and the molten iron is poured in. The molten iron quickly fills the rectangular sleeve. The sprue of the independent ceramic tube corresponding to the rectangular sleeve can be lifted into the molten iron. Since the molten iron in the rectangular sleeve is always kept full, the filling pressure is high. Step 8: After casting is completed, the temperature of the casting in the sand box is measured and recorded using the thermocouples attached during molding. When the temperature drops to about 350℃, the sand is removed and the casting is lifted out. After cooling to room temperature, the gating system and slag removal system are removed, the surface is polished, and the casting is inspected and put into storage.
2. The casting method for solving the problem of multiple parts failing to form in a single casting mold in lost foam casting according to claim 1, characterized in that, In step one, both the diameter of the paper tube gating system and the direct gating system is φ70mm.
3. The casting method for solving the problem of multiple parts failing to form in a single casting mold in lost foam casting according to claim 2, characterized in that, The rectangular base in step two has dimensions of 435*245*35mm and a round opening diameter of φ70mm; the rectangular sleeves in steps four and five have a height of 300mm.
4. The casting method for solving the problem of multiple parts failing to form in a single casting mold in lost foam casting according to claim 1, characterized in that, The resin addition ratio in the molding sand used in steps three and four is 1.0%, ensuring that the molding sand strength is greater than 1.5 MPa.
5. The casting method for solving the problem of multiple parts failing to form in a single casting mold according to claim 4, characterized in that, In step five, the resin addition ratio in the molding sand is 1.0%, ensuring that the molding sand strength is greater than 2.2 MPa.
6. The casting method for solving the problem of multiple parts failing to form in a single casting mold in lost foam casting according to claim 1, characterized in that, In step five, the rectangular sleeve on the metal mesh has an edge that is 30-50mm higher than the refractory brick.
7. The casting method for solving the problem of multiple parts failing to form in a single casting mold in lost foam casting according to claim 1, characterized in that, In step six, after drying the alcohol-based coating and before pouring, a pressure iron is placed on the surface of the sand box. The weight of the pressure iron is seven times the weight of the pouring weight to resist the pressure of the molten iron pouring and the pressure formed after the foam vaporizes. At the same time, the negative pressure pipe is connected and the negative pressure equipment is turned on to reduce the pressure in the sand box and allow the gas in the cavity to be discharged quickly.