3D printing sand casting process of high-strength copper alloy explosion-proof tool

Abstract

The present application relates to a kind of high-strength copper alloy explosion-proof tool 3D printing sand casting process, belong to the technical field of casting of explosion-proof tool. Including the following steps: S1, using 3D printing technology to make sand mold;S2, the 3D printing sand mold of design needs to be printed is layered;S3, according to the material matching requirement of beryllium bronze, aluminum bronze explosion-proof tool material matching, according to the proportioning is added to the furnace and is smelted, the copper alloy melt of smelting is poured into the cavity of three-dimensional solid sand mold of step S2, and metal is completely filled cavity and is poured;S4, after pouring, wait for melt cooling and solidification;After the cooling of casting, remove three-dimensional solid sand mold, obtain casting;Then, the post-processing procedure of casting is carried out, and the final finished product is obtained.The present application realizes that copper alloy explosion-proof tool can be efficiently, mass-produced, process is stable, controllable, greatly reduces the influence of human factors.

Description

Technical Field

[0001] This invention relates to the field of explosion-proof tool casting technology, and more specifically, to a 3D printing sand casting process for high-strength copper alloy explosion-proof tools. Background Technology

[0002] Copper alloy casting, a type of non-ferrous metal casting, has a history of over a thousand years. Traditional copper alloy casting relies on manual molding, with core steps including: ① Sand box positioning (placing the model in the sand box, reserving the casting position, and ensuring alignment of the upper and lower boxes using positioning pins). ② Molding sand treatment (screening, filling, and compaction). ③ Parting surface repair and demolding (hammering and demolding to remove the model from the sand mold). ④ Finishing (setting up the gating system). Manual molding is flexible and low-cost, but it also has the following drawbacks: (1) Unstable casting quality. Analysis of operation steps: ① Sand box positioning is done by positioning pins, which has a certain amount of looseness and is prone to misalignment. ② Sand mold treatment is done by manually sifting, filling and compacting sand. The air permeability and compaction of the sand cannot be effectively controlled, which can easily cause defects such as bulging and porosity. ③ Inadequate parting surface repair will result in burrs after mold closing, misalignment, and casting misalignment. Sand particles falling into the cavity during the repair process can easily cause sand hole defects in the casting. The force of hammering when demolding and the amount of shaking of the mold in the cavity all affect the dimensional accuracy of the casting. The dimensional accuracy of manual sand casting is ±0.5mm, and large castings can even reach ±1mm or more. ④ Molding and finishing: the operator sets the casting system himself, which is highly flexible and cannot guarantee uniformity. The setting of the casting system directly affects the surface quality and internal quality of the casting, such as shrinkage porosity, porosity, incomplete filling and cold shut, sand flushing and sand holes.

[0003] (2) Human factors greatly affect the quality of castings. As can be seen from the operation steps of manual molding, there are a great deal of uncontrollable human factors. Skilled workers need to operate with precision, and the experience and technical level of the operators are strictly required. However, when the staff turnover rate is high or the training is insufficient, problems such as incorrect molding and uneven wall thickness are likely to occur. The molding of complex castings (such as those with movable blocks or curved parting surfaces) is more difficult and more dependent on technology.

[0004] (3) Low production efficiency. Hand-molding is like making handicrafts, which is tedious and complicated and very slow. A normal foundry worker can make 5-10 boxes per hour. Hand-molding is suitable for single-piece or small-batch production.

[0005] (4) High labor intensity. Manual molding relies on manual labor to complete steps such as sand filling, compaction, mold repair and demolding. These processes are slow and labor-intensive. Especially for some large castings, it may even require several people to complete them at the same time.

[0006] (5) There are limitations to hand-shaping. Some products with complex shapes and large volumes are difficult to shape by hand. Summary of the Invention

[0007] This invention overcomes the problems of unstable casting quality, significant human influence, low production efficiency, high labor intensity, and limited casting shape in the prior art, and provides a 3D printing sand casting process for high-strength copper alloy explosion-proof tools.

[0008] The present invention adopts the following technical solution: A 3D printing sand casting process for high-strength copper alloy explosion-proof tools includes the following steps: S1. Use 3D printing technology to create 3D printed sand molds; S2. Layer the designed 3D printing sand model to be printed; first, lay a layer of sand containing curing agent, then the print head sprays adhesive according to the preset model cross-section pattern, and the sand particles are bonded together through intermolecular cross-linking polymerization, and finally cured to form a cured cross-section; repeatedly lay sand layers, spray adhesive, and cure, and finally build up layer by layer to form a three-dimensional solid sand model. S3. Add the raw materials required for beryllium bronze or aluminum bronze into the furnace for smelting, and pour the molten copper alloy into the cavity of the three-dimensional solid sand mold made in step S2. After the metal completely fills the cavity, pour the metal. S4. After pouring, wait for the melt to cool and solidify; after the casting cools to room temperature (4-40℃), remove the three-dimensional solid sand mold to obtain the casting; then perform post-processing on the casting to obtain the final product.

[0009] Preferably, step S1 is as follows: First, the product is designed using CAD software, then converted into a three-dimensional model using UG software, the gating system is designed, and the machining allowance and draft angle are designed in combination with the precision of 3D printing. Then, the mold is split into an upper cavity and a lower cavity, and then the mold is closed.

[0010] Preferably, in step S1, the length, width, and thickness of the sand mold in the gating system are 50-70 mm larger than the casting dimensions; Step S1: The ambient temperature in the gating system is designed to be 22-28℃, and the humidity is designed to be below 60%. In step S1, the machining allowance is controlled at 0.5-1.0mm, and the draft angle is 4-7°.

[0011] Preferably, the layer thickness of the three-dimensional solid sand mold stacked layer by layer in step S2 is controlled at 0.20-0.30 mm; In step S2, the sand layer is 100-140 mesh ceramsite sand, and the three-dimensional solid sand mold includes an upper cavity and a lower cavity.

[0012] Preferably, the adhesive in step S2 is furan resin, and the amount of adhesive used is 1.5%-3.0% of the mass of the sand particles; the curing agent is an aliphatic HDI type polyurethane curing agent (KPH-F-28), and the amount of curing agent used is 0.18-0.60% of the mass of the sand particles. The viscosity of the adhesive is ≤20 mPa·s, and the total acidity is ≤30%.

[0013] Preferably, after the overall spraying is completed in step S2, the remaining loose sand is cleaned by using a vibrating screen and airflow. After cleaning, ceramic coating is brushed into the interior of the upper and lower cavities.

[0014] Preferably, in step S3, beryllium bronze is melted to 1350-1400℃ and aluminum bronze is melted to 1250-1300℃, then heating is stopped and the temperature is lowered to 1100-1200℃ for casting.

[0015] Preferably, in step S3, the raw materials required for beryllium bronze contain 1.8-3.0% beryllium by mass, more than 0.20% nickel by mass, and the balance is copper; the raw materials required for aluminum bronze contain 8.0-12.0% aluminum by mass, 3.0-6.0% nickel by mass, less than 5% iron by mass, and the balance is copper.

[0016] Preferably, in step S3, the three-dimensional solid sand mold is fixed in place using a card box tool before use.

[0017] Preferably, the card box tool includes a card mounting plate, a card body, a first locking member, and a second locking member. The card mounting plate contacts and presses against the parting surface of the upper and lower cavities of the three-dimensional solid sand mold. The card body is sleeved on the outside of the three-dimensional solid sand mold. The lower part of the card body is locked to the bottom of the three-dimensional solid sand mold. The middle part of the card body is connected to the second locking member, which is connected to the card mounting plate to lock it. The upper end of the card body is connected to the first locking member, which presses against the three-dimensional solid sand mold from the top.

[0018] The beneficial effects of this invention are: This invention utilizes advanced 3D printing technology to print casting models, replacing traditional manual modeling. Compared to traditional mold making, it eliminates storage and maintenance costs. Once the initial design is validated through subsequent testing, and with consistent materials and environment, repeatable sand molds can be produced continuously, preventing product quality instability caused by human factors. Production efficiency is increased, manpower is reduced, and labor intensity is decreased. Almost any complex geometric shape, from the smallest to large castings of 2000*1000*1000mm, can be produced. The entire production process, from design to pouring, can be predicted and monitored, maximizing product quality assurance. This invention enables efficient, mass production of copper alloy explosion-proof tools with stable and controllable processes, significantly reducing the impact of human factors. This invention is particularly suitable for scenarios with complex shapes or requiring flexible design, supporting rapid prototyping through a lightweight cartridge design to meet the demands of high-efficiency casting. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the card box device of the present invention; In the attached diagram, 1-loading plate, 2-jaw fixture body, 3-first locking element, 4-second locking element, 5-upper cavity, 6-lower cavity. Detailed Implementation

[0020] Example 1 This invention uses advanced 3D printing technology to create sand molds. (1) First, the handle of the 48" beryllium bronze explosion-proof pipe wrench was designed using CAD software, and then converted into a three-dimensional solid model using UG software. The machining allowance was 1mm and the draft angle was 6°. Then, the mold was split into an upper cavity and a lower cavity, and the mold was closed. The external dimensions of the sand mold were designed to be 1215*330*170mm. The temperature was controlled at 22-28℃ and the humidity was below 60%. The length, width and thickness of the sand mold in the gating system were designed to be 50mm larger than the dimensions of the casting.

[0021] (2) The model is layered, with the layer thickness controlled at 0.28 mm. 120-140 mesh ceramsite containing KPH-F-28 curing agent is selected to ensure a balance between high-temperature strength and collapsibility, and to guarantee good air permeability. The equipment automatically lays a layer of sand, and then the print head selectively sprays furan resin binder according to the preset model cross-sectional pattern. The inkjet parameters are set as follows: flash spray frequency 12000, flash spray effective time 2s, flash spray interval 2s. The binder has a low viscosity ≤20 mPa·s, a total acidity ≤30%, and accounts for 3.00% of the weight of the ceramsite sand. The curing agent accounts for 0.50% of the weight of the ceramsite sand. The furan resin and the curing agent undergo a rapid chemical reaction upon contact with the sand particles, and through intermolecular cross-linking polymerization, the sand particles are firmly bonded together to form a cured cross-section. This process of spreading powder, spraying, and curing is repeated until layers are finally stacked to form a three-dimensional solid sand model. After the overall spraying is completed, a vibrating screen and airflow are used to clean away any remaining loose sand. After cleaning, a ceramic coating is applied to the inside of the mold cavity. The melting point of the ceramic coating typically exceeds 1650℃, maintaining structural stability at high temperatures, effectively isolating heat, slowing down the cooling rate of the casting, and improving the solidification process. By enhancing the surface strength of the mold, the erosion of the molding sand by the molten metal is reduced.

[0022] (3) such as Figure 1 As shown, the three-dimensional solid sand mold is fixed by a clamping device, which includes a clamping plate 1, a clamping body 2, a first locking member 3, and a second locking member 4. The clamping plate 1 contacts and presses against the parting surface of the upper cavity 5 and lower cavity 6 of the three-dimensional solid sand mold. The clamping body 2 is sleeved on the outside of the three-dimensional solid sand mold, with its lower part clamped to the bottom of the three-dimensional solid sand mold. The middle part of the clamping body 2 is connected to the second locking member 4, which is connected to the clamping plate 1 to lock it in place. The upper end of the clamping body 2 is connected to the first locking member 3, which presses against the three-dimensional solid sand mold from the top. This forms multiple fixing mechanisms, eliminating the need for the traditional sand casting's casing and embedding box. The high strength and clamping fixation effectively avoid problems such as mold misalignment, mold lifting, or sparking during the pouring process.

[0023] The materials were proportioned according to the material quality requirements for beryllium bronze explosion-proof tools: 1.82% beryllium, 0.24% nickel, and 97.94% copper. These were added sequentially to a medium-frequency induction furnace for melting. Heating was stopped when the temperature reached 1380℃, and casting was carried out after the temperature dropped to 1150℃.

[0024] (4) Slowly pour the copper alloy melt at a suitable temperature into the cavity of the three-dimensional solid sand mold to ensure that the metal fully fills the cavity. After pouring, wait for the melt to cool and solidify. After the casting cools to room temperature, remove the three-dimensional solid sand mold to obtain the casting.

[0025] After the casting has cooled, the sand mold is removed by vibration to obtain the casting. Then, the casting undergoes cleaning, grinding, machining, and heat treatment (quenching and solution treatment temperature 780℃, aging temperature 320℃) to obtain the final product. The technical parameters of the finished product are tested, and the results are shown in Table 1.

[0026] Example 2 First, the 290mm aluminum bronze explosion-proof valve wrench was designed using CAD software. The model was converted into a 3D solid model using UG software. A machining allowance of 0.5mm and a draft angle of 4° were designed. Due to the small size, a two-part mold was designed, followed by parting the mold into an upper and lower cavity, and then closing the mold. The designed dimensions of the 3D printed sand mold are 570*320*150mm. The temperature was controlled between 22-28℃, and the humidity below 60%. The length, width, and thickness of the sand mold in the gating system were designed to be 70mm larger than the casting dimensions.

[0027] (2) The model is layered, with the layer thickness controlled at 0.20 mm. 120-140 mesh ceramsite containing curing agent KPH-F-28 is selected to ensure a balance between high-temperature strength and collapsibility, and to guarantee good air permeability. The equipment automatically lays a layer of sand, and then the print head selectively sprays furan resin binder according to the preset model cross-sectional pattern. The inkjet parameters are set as follows: flash spray frequency 12000, flash spray effective time 2s, flash spray interval 2s. The binder has a low viscosity ≤20 mPa·s, a total acidity ≤30%, and accounts for 1.50% of the weight of the ceramsite sand. The curing agent accounts for 0.18% of the weight of the ceramsite sand. The furan resin and curing agent undergo a rapid chemical reaction upon contact with the sand particles, and through intermolecular cross-linking polymerization, firmly bond the sand particles together to form a cured cross-section. This process of powdering, spraying, and curing is repeated until layers are finally stacked to form a three-dimensional solid sand model. After the overall spraying is completed, a vibrating screen and airflow are used to clean away any remaining loose sand. After cleaning, (3) The three-dimensional solid sand mold is fixed in the same way as in Example 1; The materials are proportioned according to the material quality requirements for aluminum bronze explosion-proof tools: 10.95% aluminum, 4.45% iron, 5.45% nickel, and 79.15% copper. These are added to the furnace in sequence for melting. Heating is stopped when the melting temperature reaches 1250℃, and casting is performed after the temperature drops to 1100℃.

[0028] (4) Slowly pour the copper alloy molten liquid at a suitable temperature into the three-dimensional solid sand mold cavity to ensure that the metal fully fills the cavity. After pouring, wait for the molten liquid to cool and solidify.

[0029] After the casting has cooled, the sand mold is removed by sandblasting to obtain the casting. Then, the casting undergoes cleaning, grinding, and machining processes to obtain the final product. The technical parameters of the finished product are tested, and the results are shown in Table 1.

[0030] Example 3 (1) First, the loading platform of the 2-ton aluminum bronze explosion-proof hydraulic loader was designed using CAD software, and then converted into a three-dimensional solid model using UG software. The machining allowance was designed to be 1mm, and the draft angle was 7°. Then, the mold was split into an upper cavity and a lower cavity, and the mold was closed. The external dimensions of the 3D printed sand mold were designed to be 1400*620*130mm. The temperature was controlled at 22-28℃ and the humidity was below 60%. The length, width, and thickness of the sand mold in the gating system were designed to be 65mm larger than the dimensions of the casting.

[0031] (2) The model is layered, with the layer thickness controlled at 0.30 mm. 120-140 mesh ceramsite containing curing agent KPH-F-28 is selected to ensure a balance between high-temperature strength and collapsibility, and to guarantee good air permeability. The equipment automatically lays a layer of sand, and then the print head selectively sprays furan resin binder according to the preset model cross-sectional pattern. The inkjet parameters are set as follows: flash spray frequency 12000, flash spray effective time 2s, flash spray interval 2s. The binder has a low viscosity ≤20 mPa·s, a total acidity ≤30%, and accounts for 2.60% of the weight of the ceramsite sand. The curing agent accounts for 0.60% of the weight of the ceramsite sand. The furan resin and curing agent undergo a rapid chemical reaction upon contact with the sand particles, and through intermolecular cross-linking polymerization, firmly bond the sand particles together to form a cured cross-section. This process of powdering, spraying, and curing is repeated until layers are finally stacked to form a three-dimensional solid sand model. After the overall spraying is completed, a vibrating screen and airflow are used to clean away any remaining loose sand. After cleaning, (3) The three-dimensional solid sand mold is fixed in the same way as in Example 1; The materials are proportioned according to the material quality requirements for aluminum bronze explosion-proof tools: aluminum 11.50%, iron 4.45%, nickel 5.45%, and copper 78.60%. These are added to the furnace in sequence for melting. Heating is stopped when the melting temperature reaches 1300℃, and casting is performed after the temperature drops to 1200℃.

[0032] (4) Slowly pour the copper alloy molten liquid at a suitable temperature into the three-dimensional solid sand mold cavity to ensure that the metal fully fills the cavity. After pouring, wait for the molten liquid to cool and solidify.

[0033] After the casting cools, the sand mold is removed by cutting to obtain the casting. Then, the casting undergoes cleaning, grinding, and machining processes to obtain the final product. The technical parameters of the finished product are tested, and the results are shown in Table 1.

[0034] Table 1 Technical parameters of the final product in the embodiment Table 2 Comparison of Examples 1-3 and Traditional Handcrafted Modeling The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A 3D printing sand casting process for high-strength copper alloy explosion-proof tools, characterized in that, Includes the following steps: S1. Use 3D printing technology to create 3D printed sand molds; S2. Layer the designed 3D printing sand model to be printed; first, lay a layer of sand containing curing agent, then the print head sprays adhesive according to the preset model cross-section pattern, and the sand particles are bonded together through intermolecular cross-linking polymerization, and finally cured to form a cured cross-section. Repeatedly lay sand layers, spray adhesive, and cure, eventually stacking them layer by layer to form a three-dimensional solid sand mold; S3. Add the raw materials required for beryllium bronze or aluminum bronze into the furnace for smelting, and pour the molten copper alloy into the cavity of the three-dimensional solid sand mold made in step S2. After the metal completely fills the cavity, pour the metal. S4. After pouring, wait for the molten metal to cool and solidify; after the casting cools to room temperature, remove the three-dimensional solid sand mold to obtain the casting; then perform post-processing on the casting to obtain the final product.

2. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 1, characterized in that, Step S1 is as follows: First, design the product using CAD software, then convert it into a 3D model using UG software, design the gating system, and design the machining allowance and draft angle based on the precision of 3D printing. Then, perform parting, dividing the 3D printing sand mold into an upper cavity and a lower cavity, and then closing the mold.

3. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 2, characterized in that, Step S1: Design the sand mold in the gating system to be 50-70mm larger than the casting dimensions. Step S1: The ambient temperature in the gating system is designed to be 22-28℃, and the humidity is designed to be below 60%. In step S1, the machining allowance is controlled at 0.5-1.0mm, and the draft angle is 4-7°.

4. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 1, characterized in that, In step S2, the layer thickness of the three-dimensional solid sand mold formed by stacking layers is controlled at 0.20-0.30 mm; In step S2, the sand layer is 100-140 mesh ceramsite sand, and the three-dimensional solid sand mold includes an upper cavity and a lower cavity.

5. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 4, characterized in that, The adhesive used in step S2 is furan resin, and the amount of adhesive used is 1.5%-3.0% of the mass of the sand particles. The curing agent is an aliphatic HDI type polyurethane curing agent, and the amount of curing agent used is 0.18-0.60% of the mass of the sand particles. The viscosity of the adhesive is ≤20 mPa·s, and the total acidity is ≤30%.

6. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 4, characterized in that, After the overall spraying is completed in step S2, residual loose sand is removed by using a vibrating screen and airflow. After cleaning, ceramic coating is brushed into the interior of the upper and lower cavities.

7. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 1, characterized in that, In step S3, beryllium bronze is melted to 1350-1400℃ and aluminum bronze is melted to 1250-1300℃. Heating is then stopped, and the temperature is lowered to 1100-1200℃ for casting.

8. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 1, characterized in that, In step S3, the raw materials required for beryllium bronze contain 1.8-3.0% beryllium by mass, more than 0.20% nickel by mass, and the balance is copper; the raw materials required for aluminum bronze contain 8.0-12.0% aluminum by mass, 3.0-6.0% nickel by mass, less than 5% iron by mass, and the balance is copper.

9. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 1, characterized in that, In step S3, the three-dimensional solid sand mold is fixed in place using a clamping box before use.

10. The 3D printing sand casting process for a high-strength copper alloy explosion-proof tool according to claim 9, characterized in that, The card box tool includes a card mounting plate, a card body, a first locking member, and a second locking member. The card mounting plate contacts and presses against the parting surface of the upper and lower cavities of the three-dimensional solid sand mold. The card body is sleeved on the outside of the three-dimensional solid sand mold. The lower part of the card body is locked to the bottom of the three-dimensional solid sand mold. The middle part of the card body is connected to the second locking member, which is connected to the card mounting plate to lock it. The upper end of the card body is connected to the first locking member, which presses against the three-dimensional solid sand mold from the top.

Images